JP2010020990A - Planar heating element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a planar heating element which can generate heat uniformly to the surrounding of the planar heating element, can be installed with good processability and has excellent thermal stability. <P>SOLUTION: The planar heating element is constructed of a heating element 5 having a core electrode 2 as an inner electrode, a polymer resistor 3 which is installed around the core electrode 2 and contains a conductor of which a main component is crosslinked through a reactive resin, and an outer electrode 4 installed around the surface of the polymer resistor 3, and a lamination film of sheet shape consisting of a metal film 6 and a thermal fusion film 7 for supporting the heating element 5. Thus, the planar heating element having PTC characteristics superior in uniform heating for a long period can be achieved. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a planar heating element using a polymer resistor having excellent PTC characteristics.

  Conventionally, one of the heating portions of this type of planar heating element is produced by extrusion molding on two parallel electrodes made of copper wire or the like.

  FIG. 5 shows a specific configuration, and the resistor 50 is formed by dispersing one or more conductivity imparting agents such as metal powder, carbon black, and graphite in a crystalline thermoplastic resin. A pair of electrodes 51 are provided in this and energized to generate heat.

This heating element has PTC characteristics. Here, the PTC characteristic means a resistance temperature characteristic in which the resistance value increases as the temperature rises, and when the temperature reaches a certain temperature, the resistance value increases rapidly. A heating element having PTC characteristics can provide a self-temperature adjusting function (see, for example, Patent Document 1).
JP-A-62-188194

  However, the conventional heating element has a structure in which two electrodes 51 are arranged in parallel, so that when energized, heat is generated between the two embedded electrodes 51 and heat is not easily transmitted to the surroundings.

  Further, the surface of the heating element is in a non-uniform heat generation state in which the temperature of the flat surface portion is high and the temperature of the curved surface portion (the side opposite to the counter electrode of the electrode) is low.

  Furthermore, since the cross section of the heating element is elliptical, the degree of freedom is low, and there is a problem that workability such as sewing and pasting with a support is poor.

  The present invention solves the above-described conventional problems, and provides a sheet heating element with high thermal stability that can uniformly generate heat around the sheet heating element and can be installed with good workability. For the purpose.

  In order to solve the above-described conventional problems, the planar heating element of the present invention includes a core electrode as an inner electrode, and a conductor in which a main component provided around the core electrode is cross-linked through a reactive resin. And a heating element having an outer electrode provided on the surface of the polymer resistor, a metal film holding the heating element, and a sheet-like laminated film made of a heat-sealing film, It is comprised by.

  Thereby, heat due to heat generation is transmitted radially from the core electrode, and further, heat is transmitted on the surface by the metal film. And the sheet | seat heat generating body which has the PTC characteristic excellent in heat uniformity over a long period of time is realizable by heat-seal | fusing.

  In the planar heating element of the present invention, electrodes are arranged at the center and the outer periphery, and the metal film enables uniform heat generation throughout the heating element. As a result, it is possible to realize a planar heating element having PTC characteristics with excellent heat uniformity over a long period of time.

  According to a first aspect of the present invention, there is provided a polymer resistor comprising a core electrode as an inner electrode, a conductor in which a main component provided around the core electrode is cross-linked via a reactive resin, and the polymer resistor A heating element having an outer electrode provided on the surface of the body, and a sheet-like laminated film made of a metal film and a heat-sealing film for holding the heating element.

  Therefore, when a voltage is applied between the core electrode and the outer electrode, an electric field is generated radially around the core electrode, and the polymer resistor generates heat. Further, the entire sheet heating element can be uniformly heated by the heat conduction of the metal film, and since it is fixed by the heat fusion film, a sheet heating element excellent in soaking stability can be realized.

  The second invention is particularly characterized in that the outer electrode of the first invention is a flexible electrode wound around the surface of the polymer resistor.

  When a polymer resistor is covered with a metal foil or a metal plate, there is a disadvantage that the planar heating element lacks flexibility. Therefore, a slit is formed by winding a strip-shaped electrode around the surface of the polymer resistor in a spiral shape, and flexibility can be ensured by the cut.

  Thereby, not only can the entire sheet heating element be heated uniformly, but also a heating element excellent in processing can be realized.

  According to a third aspect of the present invention, there is provided a core electrode as an inner electrode, a polymer resistor including a conductor in which a main component provided around the core electrode is cross-linked through a reactive resin, and an outer electrode. The heating element includes a metal film, and a sheet-like heat-sealing film that holds the heating element. The polymer resistor and the metal film are electrically connected.

  By using the metal film as the outer electrode, the number of members can be reduced, and the manufacturing process can be simplified.

  In the fourth invention, in particular, a slit is provided in the metal film of the third invention, and the metal film and the polymer resistor are firmly pressure-bonded by the heat-sealing film that has come out of the slit.

  As a result, it is possible to realize a sheet heating element that is stable in power feeding and has excellent soaking stability.

  In the fifth invention, in particular, the reactive resin contained in the polymer resistor of the first or third invention has a composition containing at least one functional group of an epoxy group, an oxazoline group, and a maleic anhydride group. It is.

  Thereby, the chemical bond by reaction is produced and thermal stability can be improved. And since physical, chemical, and electrical behavior can be stabilized, stable PTC characteristics can be realized over a long period of time.

  In a sixth invention, the conductor of the first or third invention is formed by blending at least a conductive inorganic oxide.

  Unlike carbon-based materials such as carbon black, the conductive inorganic oxide is a material that does not easily burn. Therefore, the polymer resistor including the conductive inorganic oxide exhibits flame retardancy or incombustibility against external ignition. Therefore, reliability can be ensured over a long period of time.

  The seventh invention is characterized in that the laminated film of the first or third invention is used as an exterior film of a vacuum heat insulating material formed by evacuation.

  By providing a highly heat-insulating vacuum heat insulating material on one side of the heating wire, it is possible to increase the amount of heat generated in one direction along with the uniformity of heat, or to reduce power consumption in one direction.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. It should be noted that the present invention is not limited to the embodiments described in detail below.

(Embodiment 1)
1 and 2, a sheet heating element 1 has a core electrode 2 as an inner electrode, a polymer resistor 3 containing a conductor, and an outer electrode provided around the surface of the polymer resistor 3. 4, and a metal film 6, a heat-sealing film 7, and a protective film 8 that sandwich a plurality of the heating elements 5, are formed into a sheet shape.

  The core electrode 2 is a conductive metal wire, and 19 tin-plated copper wires having a diameter of 0.2 mm were used. This can be made of a silver-copper alloy wire in consideration of reliability such as prevention of disconnection.

  In addition, not only a winding wire but a single wire and a braided wire can also be used.

  The polymer resistor 3 is produced by kneading and molding a resin composition and a conductor. The resin composition has a cross-linked structure by blending a reactive resin with a reactive resin.

  The reactive resin may be any olefinic thermoplastic resin that exhibits PTC characteristics, such as ethylene vinyl acetate copolymer, ethylene ethyl acrylate copolymer, ethylene methyl methacrylate copolymer, ethylene methacrylic acid. There are copolymers.

  In the present embodiment, an ethylene vinyl acetate copolymer having a melting point of about 60 ° C. was used in anticipation of a sudden resistance change from 60 ° C. to 80 ° C.

  As the reactive resin, an ethylene acrylic acid copolymer modified with a maleic anhydride group was used. However, a resin modified with an epoxy group or a copolymer modified with an oxazoline group can also be used.

  As the conductor, a conductive inorganic oxide in which a primary particle diameter of 20 nm carbon black and needle-like titanium oxide as a base and a SnO2 / Sb conductive layer were coated was used.

  Furthermore, a phosphate ester flame retardant was also added.

  By kneading with the composition as described above and extrusion molding together with the core electrode 2, the polymer resistor 3 including the core electrode 2 in the center can be produced.

  The outer electrode 4 is a strip-shaped metal foil with a thickness of 0.1 mm. This is brought into close contact with the polymer resistor 3 by being simultaneously wound while being simultaneously extruded. This can also be adhered by applying a conductive paint such as a silver-based rubber paint.

  The metal film 6 is an aluminum foil and has a thickness of 12 μm. The heat-sealing film 7 was made of unstretched polypropylene having a higher degree of crystallinity with a homopolymer, and the protective film 8 was made of polyethylene film.

  Next, an example of a method for manufacturing the planar heating element will be described.

  First, flame retardant several wt% is added to carbon black 15wt%. Then, it is mixed with 45 wt% of acicular titanium oxide coated with a conductive material.

  First, the mixture was sufficiently kneaded with 20 wt% of ethylene vinyl acetate copolymer, then blended with 10 wt% of ethylene acrylic acid copolymer modified with maleic anhydride group, and set at 170 ° C. until the viscosity change was stabilized. Kneading with a roll.

  The kneading and mixing may be performed by an apparatus such as a kneader or a twin screw extruder kneader.

  The sheet-like kneaded body was allowed to cool naturally, and then pulverized into several millimeters and four sides by a pulverizer to obtain an input material for extrusion formation.

  The heating element 5 was produced by extrusion molding. An electrode wire as the core electrode 2 prepared by winding 19 tin-plated copper wires having a diameter of 0.2 mm is prepared and set so as to be extruded together with the formed body from the center of the head of the extruder.

  Since the diameter of the polymer resistor 3 is related to the resistance value of the planar heating element 1, it is determined by the desired resistance value. In this embodiment, the head diameter is adjusted so that the thickness in the diameter direction is about 1 mm.

  Then, a strip-shaped metal foil serving as the outer electrode 4 is brought into close contact with the extruded polymer resistor 3 while being continuously wound simultaneously with extrusion.

  Here, the outer electrode 4 can be brought into close contact by reactivity with the resin or by thermal contraction by cooling.

  Finally, the outer electrode was sandwiched between laminated films laminated in the order of the protective film 8, the metal film 6, and the heat-sealing film 7 from the outside, and completed by thermocompression bonding with a laminator.

  Next, an example of how to use the planar heating element 1 will be described.

  The sheet heating element 1 is cut 100 mm, and the voltage is applied with the core electrode 2 as the positive electrode and the outer electrode 4 as the negative electrode.

  When a voltage of 2.3 V and a power of 1.5 W were applied, the temperature range was in the range of 36 ° C. to 38 ° C., and PTC characteristics were exhibited and the calorific value could be stabilized at a predetermined value.

  In the embodiment, an example in which there are two heating elements 5 is shown, but there may be one or more heating elements 5 and it is not necessary to apply them simultaneously.

  When observed by infrared thermography, uniform heat generation was realized on the entire surface of the sheet heating element 1. Furthermore, despite the small amount of flame retardant added, the fire extinguisher was extinguished even when lit with a lighter. This is considered because 40% or more of inorganic materials are blended.

(Embodiment 2)
3 and 4 show the second embodiment. A planar heating element 11 includes a core electrode 12 as an inner electrode, a polymer resistor 13 containing a conductor, a heating element 15 made of a metal film 14, and The sheet-like heat-sealing film 16 sandwiches a plurality of the heating elements 15.

  The composition of the core electrode 12 and the polymer conductor 13 is the same as in the first embodiment.

  There is no outer electrode, and the metal film 14 is used instead as an electrode.

  The metal film 14 is a stainless steel foil, has a thickness of 20 μm, and is provided with slits 17.

  The heat-sealing film 16 was a non-stretched polypropylene that was a homopolymer and increased in crystallinity.

  Next, an example of a method for manufacturing the planar heating element 11 of the present embodiment will be described.

  The method for forming the heating element 15 is the same as in the first embodiment. However, metal foil is not wound. And the heat generating body 15 was pinched | interposed with the laminated film laminated | stacked in order of the heat sealing | fusion film 16 and the metal film 14 from the outer side, and it thermocompression-bonded with the laminator, and was completed.

  At this time, the heat-sealing films 16 on both sides come into close contact with each other through the slit 17.

  The slit 17 is preferably fine and close to the heating element 15. For example, a mesh-like metal film can be used.

  Next, an example of how to use the planar heating element 11 will be described.

  The heating element 11 is cut 100 mm, the core electrode 12 is used as a positive electrode, and the extended portion 14a of the metal film 14 is used as a negative electrode to apply a voltage.

  When a voltage of 2.3 V and a power of 1.3 W were applied, the temperature range was in the range of 36 ° C. to 38 ° C., and PTC characteristics were exhibited and the calorific value could be stabilized at a predetermined value.

  In the present embodiment, the two heating elements 15 are arranged, but there may be one or more than three.

  When observed by infrared thermography, the uniform heat generation is realized over the entire surface of the sheet heating element 11 as in the first embodiment, but the structure of the present embodiment is simple and easily manufactured. Can do.

  The planar heating element according to the present invention is a heating element having PTC characteristics excellent in heat uniformity. This planar heating element can be mounted on, for example, a surface shape of a device having a combination of a continuous curved surface and a flat surface. Therefore, as a heater for heating, an electric vehicle seat, steering wheel, trim, and other electric devices that require heating. Applicable to equipment such as floor heating.

The perspective view which shows the planar heating element in Embodiment 1 of this invention. XY sectional view of FIG. The perspective view which shows the planar heating element in Embodiment 2 of this invention. XY cross section of FIG. Sectional view of a conventional sheet heating element

Explanation of symbols

2,12 core electrode 3,13 polymer resistor 4 outer electrode 5,15 heating element 6,14 metal film 7,16 heat fusion film 17 slit

Claims (6)

A core electrode as an inner electrode, a polymer resistor containing a conductor in which a main component provided around the core electrode is cross-linked through a reactive resin, and a surface provided on the surface of the polymer resistor A sheet-like heating element constituted by a heating element having a formed outer electrode, and a sheet-like laminated film made of a metal film and a heat-sealing film for holding the heating element. The planar heating element according to claim 1, wherein the outer electrode is a metal foil wound around the surface of the polymer resistor. A core electrode as an inner electrode, a polymer resistor containing a conductor in which a main component provided around the core electrode is cross-linked via a reactive resin, and a heating element having a metal film as an outer electrode And a sheet-like heat-sealing film that holds the heating element, and the polymer resistor and the metal film are electrically connected to each other. The planar heating element according to claim 3, wherein a slit is provided in the metal film, and heat fusion is performed through the slit. The planar heating element according to claim 1 or 3, wherein the reactive resin contains at least one functional group of an epoxy group, an oxazoline group, and a maleic anhydride group. The planar heating element according to claim 1 or 3, wherein the conductor is at least blended with a conductive inorganic oxide.

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