JP2014160587A - Planar heating element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive safe planar heating element.SOLUTION: A planar heating element includes: a base 2 made of an electrical insulating material; a polymer resistor 3 formed on the base 2; an electrodes 4 for supplying the power to the polymer resistor 3; and a coating material 5 made of an electrical insulating material, which covers the polymer resistor 3 and the electrode 4 and is adhered to the base 2. The electrode 4 includes: a core wire 4a made of a thermal shrinkable material; and a conductor wire 4b spirally wound on the core wire 4a. Thus, an inexpensive safe planar heating element can be provided with a simple configuration.

Description

  The present invention relates to a planar heating element useful as a heating element for heating appliances and other heating appliances.

  2. Description of the Related Art Conventionally, as a heat generating portion of a planar heating element, a material obtained by dispersing a conductive material such as carbon black, metal powder, or graphite in a resin is known. In particular, in the case of using a PTC heating element (which means an abbreviation of English Positive Temperature Coefficient, which means a positive resistance temperature characteristic) by a combination of a conductive material and a resin, a temperature control circuit is provided. Is known as a device that has advantages such as eliminating the need for components and reducing the number of components.

  For example, as shown in FIGS. 8 and 9, the planar heating element 11 having PTC characteristics is obtained by thermally welding a polymer resistor 15 to a linear electrode 14 in which an electrode thin wire 12 is covered with a covering electric material 13. Is formed. The covering electric material 13 and the polymer resistor 15 covering the electrode thin wire 12 are both made of a thermoplastic resin and conductive particles such as carbon. The polymer heating element 15 and the electrode 14 are covered with a base material 16 made of an electrically insulating material from both sides, thereby forming the planar heating element 11. The planar heating element 11 is continuously formed into a sheet shape, and is appropriately cut according to the application (see, for example, Patent Document 1).

  As shown in FIG. 8, the cut sheet heating element 11 has a lead wire 17 connected to the electrode 14 on one cutting surface of the sheet heating element 11, and an insulation treatment is performed on both cutting surfaces. As the insulation treatment of the cut surface, a method of sealing the cut surface with a sealing material 18 made of an electrically insulating material coated with hot melt is used.

JP-A-3-84888

  However, there is a problem that the sealing material 18 is required and a sealing process step is required, resulting in an increase in cost. In addition, when bubbles are generated when the cut surface is sealed with the sealing material 18, there is a risk that quality problems may occur in terms of safety, such as deterioration of the polymer resistor due to long-term use and peeling of the sealing material 18. There is.

  The present invention has been made to solve the above-described conventional problems, and an object thereof is to provide a low-cost and safe planar heating element.

  In order to solve the above problems, the present invention provides a base material made of an electrically insulating material, a polymer resistor disposed on the base material, an electrode for supplying power to the polymer resistor, and the polymer resistor. A covering material made of an electrically insulating material that covers a body and the electrode and is bonded to the base material is provided, and the electrode is configured to thermally contract.

  According to the present invention, it is possible to provide a low-cost and safe planar heating element with a simple configuration.

(A) Schematic configuration diagram showing a state after laminating the planar heating element in Embodiment 1 of the present invention, (b) Schematic configuration diagram showing a state after the heat treatment step of the planar heating element Sectional view taken along the line AA of FIG. 1B of the sheet heating element according to the first embodiment. Side view of electrode of planar heating element in the first embodiment Schematic of laminating equipment for planar heating element in the first embodiment (A) BB sectional view of FIG. 1 (b) before the heat treatment of the planar heating element in the first embodiment, (b) B- of FIG. 1 (b) after the thermal treatment of the planar heating element. B cross section (A) Schematic configuration diagram showing a state after laminating a planar heating element in Embodiment 2 of the present invention, (b) Schematic engineering drawing showing a state after the heat treatment step of the planar heating element Schematic of laminating equipment for planar heating elements in the second embodiment Plan view showing a conventional planar heating element A perspective view showing a conventional sheet heating element

  According to a first aspect of the present invention, there is provided a base material made of an electrically insulating material, a polymer resistor disposed on the base material, an electrode for supplying power to the polymer resistor, the polymer resistor and the electrode. And a covering material made of an electrically insulating material to be bonded to the base material. The electrode is configured to thermally shrink.

  With this configuration, in the manufacturing process of the planar heating element, by heating the planar heating element, the electrode contracts, the electrode enters the base material and the coating material, and the edges of the base material and the coating material are formed. Sealed. Therefore, the cut surface can be sealed without using a sealing material, cost can be reduced, entrainment of bubbles can be suppressed, and safety and quality can be improved.

  According to a second invention, in the first invention, the electrode is composed of a core wire made of a heat-shrinkable material and a conductive wire spirally wound around the core wire.

  With this configuration, the heat treatment of the planar heating element causes the core wire to contract, and the conductor wound around the core wire contracts following the contraction of the core wire, so that the electrode can be contracted.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the present embodiment.

(Embodiment 1)
FIG. 1 is a schematic configuration diagram of a planar heating element according to Embodiment 1 of the present invention. FIG. 1 (a) shows a state after lamination of the planar heating element, and FIG. 1 (b) shows a planar heating element. The state after the heat treatment process is shown. 2 is a cross-sectional view taken along the line AA of FIG. 1B, FIG. 3 is a side view of the electrode, FIG. 4 is a schematic view of a laminating apparatus, FIG. 5 is a schematic view showing heat treatment, and FIG. 1B is a cross-sectional view taken along the line BB in FIG. 1B showing the planar heating element before the heat treatment, and FIG. 5B is a cross-sectional view taken along the line BB in FIG. 1B showing the planar heating element after the heat treatment. is there.

  The planar heating element 1 includes a base material 2 made of an electrically insulating material such as polyethylene terephthalate, a polymer resistor 3 disposed on the base material 2, and a pair of electrodes 4 for supplying power to the polymer resistor 3. And a covering material 5 made of an electrically insulating material such as polyethylene terephthalate, which covers the polymer resistor 3 and the electrode 4 and is thermally welded to the base material 2, and the surface of the covering material 5 on the base material 2 side. The hot melt 6 is applied. In the present embodiment, a polymer resistor having PTC characteristics is used as the polymer resistor 3.

  FIG. 3 is a side view of electrode 4 in the first embodiment. The electrode 4 is composed of a core wire 4a and a conducting wire 4b in which the core wire 4a is spirally wound around the outer periphery, and the conducting wire 4b is wound in a state having an interval as shown in FIG.

  As the core wire 4a, an insulating wire which causes thermal contraction can be used. Specifically, organic materials having heat resistance such as polyester, polyamide, polyvinyl chloride, polyacrylonitrile, polyurethane, polyethylene naphthalate, polypropylene, and polylactic acid fiber can be used.

  A conventionally well-known thing can be used as the conducting wire 4b, for example, a copper wire, a nickel wire, a copper alloy wire, an aluminum wire, an iron wire etc. can be used. The conducting wire 4b may be composed of one strand, or may be composed of a plurality of strands.

  FIG. 4 shows a schematic diagram of the laminating equipment of the first embodiment.

  The laminating equipment is equipment for continuously bonding the base material 2, the polymer resistor 3, the electrode 4, and the covering material 5 into a sheet shape. Reference numeral 7 denotes a laminate roll, which is heated to about 180 ° C. By rotating the laminating roll 7, the base material 2 and the coating material 5 coated with hot melt are drawn. The surface of the covering material 5 on which the hot melt 6 is applied is the base material 2 side.

  Between the base material 2 and the covering material 5, the electrode 4 is disposed with a predetermined interval, and the polymer resistor 3 formed in advance with a predetermined size is disposed in contact with the electrode 4. In this state, it is introduced between the laminate rolls 7. By heating and pressurizing with the laminating roll 7, the base material 2 and the covering material 5 are bonded together by the hot melt 6, and the polymer resistor 3 and the electrode 4 are sealed between the base material 2 and the covering material 5. After the laminating process, the hot melt 6 is cooled to solidify the base material 2, the polymer resistor 3, the electrode 4, and the covering material 5, and cut into a size according to the application. The state of the cut polymer resistor 3 is shown in FIG.

  The planar heating element 1 cut to a predetermined size is subjected to a heat treatment process in order to stabilize the resistance value of the polymer resistor 3.

  The heat treatment temperature in the heat treatment step is set to be equal to or higher than the melting point of the hot melt 6 and equal to or higher than the temperature at which the core wire 4a of the electrode 4 contracts.

  In the heat treatment step, as shown in FIG. 5A, the planar heating element 1 is heated in a state where the stainless steel plate 8 is placed on the planar heating element 1 in order to prevent deformation of the planar heating element 1. . When the sheet heating element 1 is heated to the melting point of the hot melt 6 and reaches a temperature at which the core 4 a of the electrode 4 contracts, the electrode 4 contracts, and both ends of the electrode 4 are exposed from both edges of the base material 2 and the covering material 5. Move inward. The molten hot melt 6 flows into the space in which the electrode 4 has moved, and both ends of the planar heating element 1 are sealed. If it cools in this state, a hot melt will solidify again and the both ends of the base material 2 and the coating | covering material 5 will be sealed. The state in which the electrode 4 is contracted is shown in FIGS. 1 (b) and 5 (b).

  Simultaneously with the heat treatment process for stabilizing the resistance value of the polymer resistor 3, both ends of the planar heating element 1 can be sealed, and the work process can be simplified. Separate parts for sealing both ends of the sheet heating element 1 are not required, and the sheet heating element 1 can be provided at low cost.

The stainless steel plate 8 preferably has a groove at a position corresponding to the electrode 4. By forming the groove, almost the entire surface of the sheet heating element 1 can be pressed by the stainless steel plate 8, and the deformation of the sheet heating element 1 can be more reliably prevented, and the core wire 4a of the electrode 4 contracts. There is no hindrance. In addition, it is preferable to form a pressing portion for pressing the central portion in the longitudinal direction of the electrode 4 in the groove. By forming a holding portion that holds the center part in the longitudinal direction of the electrode 4 in the groove, the electrode 4 contracts around the center part in the longitudinal direction, so that both ends of the electrode 4 contract substantially uniformly at both ends of the sheet heating element 1. Can be configured to.
(Embodiment 2)
A second embodiment of the present invention will be described below with reference to FIGS. In the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted.

  FIG. 6 is a schematic configuration diagram of a planar heating element according to Embodiment 2 of the present invention, FIG. 6 (a) shows a state after lamination of the planar heating element, and FIG. 6 (b) is a planar heating element. The state after the heat treatment process is shown. FIG. 7 is a schematic view of the laminating equipment.

  In the first embodiment, the polymer resistor 3 formed in advance to a predetermined length is supplied in the laminating process shown in FIG. 4, but in the second embodiment, the polymer resistor 9 formed in a long shape is used. Is continuously supplied.

  In the laminating apparatus shown in FIG. 7, as in the first embodiment, the laminating roll 7 is heated to about 180 ° C., and the base roll 2 and the hot melt 6 are applied by rotating the laminating roll 7. The covering material 5 is pulled in.

  The laminate roll 7 is pulled between the base material 2 and the covering material 5 in a state where the electrode 4 is pulled in a state having a predetermined interval and the polymer resistor 9 is tensioned so as to come into contact with the electrode 4. Introduced between. By heating and pressurizing with the laminating roll 7, the base material 2 and the covering material 5 are bonded together by the hot melt 6, and the polymer resistor 9 and the electrode 4 are sealed between the base material 2 and the covering material 5. After the laminating process, the substrate 2, the polymer resistor 3, the electrode 4, and the covering material 5 are integrated and cut into a size according to the application. The planar heating element 10 in a cut state is shown in FIG.

  The planar heating element 10 cut into a predetermined size is subjected to a heat treatment process for stabilizing the resistance value of the polymer resistor 9 as in the first embodiment.

  In the heat treatment step, the planar heating element 10 is heated in a state where a stainless steel plate is placed on the planar heating element 10 in order to prevent deformation of the planar heating element 10 as in the first embodiment. The stainless steel plate of the second embodiment is configured to press the portion of the sheet heating element 10 where the polymer resistor 9 and the electrode 4 are not disposed.

  When the sheet heating element 10 is heated to the melting point of the hot melt 6 and reaches the temperature at which the core wire 4a of the electrode 4 contracts, the electrode 4 contracts, and both ends of the electrode 4 are exposed from both edges of the base material 2 and the covering material 5. Move inward. Further, in the state in which the hot melt 6 is solidified, the polymer resistor 9 is held in a state of being pulled by the hot melt 6 due to the tension at the time of lamination. The both ends of the polymer resistor 9 move to the inner side from both edges of the base material 2 and the covering material 5. The amount of contraction between the electrode 4 and the polymer resistor 9 is adjusted to be substantially the same. The molten hot melt 6 flows into the space in which the electrode 4 and the polymer resistor 9 are moved, and both ends of the planar heating element 10 are sealed. If it cools in this state, a hot melt will solidify again and the both ends of the base material 2 and the coating | covering material 5 will be sealed. FIG. 6B shows the planar heating element 10 in a state where both ends of the electrode 4 and the polymer resistor 9 are moved.

  Simultaneously with the heat treatment step for stabilizing the resistance value of the polymer resistor 9, both ends of the sheet heating element 10 can be sealed, and the work process can be simplified. Separate parts for sealing both ends of the sheet heating element 10 are not required, and the sheet heating element 10 can be provided at low cost.

  In addition, it is preferable that the stainless steel plate forms a pressing portion that presses the longitudinal center portion of the planar heating element 10. By pressing the electrode 4 and the polymer resistor 9 in the center portion in the longitudinal direction of the planar heating element 10 with the holding portion, the electrode 4 and the polymer resistor 9 contract around the center portion in the longitudinal direction. The both ends of the molecular resistor 9 can be configured to contract substantially uniformly at both ends of the planar heating element 10.

  In the embodiment of the present invention, the hot melt 6 is applied to the covering material 5, but the hot melt 6 may be applied to the base material 2, and both the base material 2 and the covering material 5 are hot. Melt 6 may be applied.

  Further, in the embodiment of the present invention, the heat treatment process for stabilizing the resistance value of the polymer resistor 9 and the heat treatment process for contracting the electrode 4 are combined, but the temperature required for each process is different. Thus, the heat treatment may be performed separately.

  As described above, the planar heating element according to the present invention does not perform the insulation processing of the divided cut surface, and can maintain electrical safety, so that the highly safe planar heating element that can be manufactured at low cost. It can be used for floor heating appliances, automobile door mirrors, washstand mirrors, in-vehicle battery heaters, and other heating devices for dew / frost removal.

DESCRIPTION OF SYMBOLS 1, 10 Planar heating element 2 Base material 3, 9 Polymer resistance body 4 Electrode 4a Core wire 4b Conductor 5 Coating material 6 Hot melt

Claims (2)

A base material made of an electrically insulating material, a polymer resistor disposed on the base material, an electrode for supplying power to the polymer resistor, and covering the polymer resistor and the electrode and bonding to the base material And a covering material made of an electrically insulating material, wherein the electrode is configured to thermally shrink. The planar heating element according to claim 1, wherein the electrode is composed of a core wire made of a heat-shrinkable material and a conductive wire spirally wound around the core wire.

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