JPH0572075B2 - - Google Patents

Description

[Detailed description of the invention]

(Technical Field) The present invention relates to a cord-shaped heater, and particularly to a cord-shaped heater used for electric blankets, electric carpets, and the like. (Background Art) Conventionally, cord-shaped heaters used for electric blankets, electric carpets, etc. have been constructed using metal such as copper alloy around the outer periphery of a string-shaped winding core 1 made of polyester fiber strands, as shown in FIG. A resistor 2 is spirally wound with a predetermined gap, the upper surface of this metal resistor 2 is coated with a heat-sensitive resin layer 3, and a heat-sensitive electrode 4 made of a metal conductor is provided on the outside of the resistor 2 in a spiral manner in correspondence with the metal resistor 2. The thermosensitive resin layer 3 is wound in a shape to detect temperature-impedance changes, and a separation layer 5 made of polyester tape or the like is spirally wound around the outside of the thermosensitive resin layer 3. An insulating coating layer 6 made of vinyl chloride or the like is laminated on the outer periphery. The material and dimensions of the metal resistor 2 are appropriately selected depending on the amount of heat generated by the electric blanket or electric carpet. In addition, the heat-sensitive resin layer 3
It consists of a negative-characteristic plastic thermistor, forming a heat-sensitive heating element as a whole. As shown in Fig. 2, an electric carpet equipped with such a cord-shaped heater is made of a cord-shaped heater H with thermal adhesive applied to the back side of a heat-uniforming sheet C with thermal adhesive applied to both sides of metal foil. are wired in a predetermined wiring pattern by heating and pressurizing with a heat press, etc., and the backing material B is applied to the upper surface, and the surface material A is applied to the surface of one heat-uniforming sheet C. It is configured. Since the conventional electric carpet with such a configuration uses the above-mentioned cord-shaped heater as a heating element, when an external load is applied to the cord-shaped heater H, the metal resistor 2 may be cut or the finish may be damaged. The cord-shaped heater H had irregularities on its surface, which caused problems such as poor seating comfort. Therefore, as a countermeasure to prevent this, it is possible to increase the thickness of the surface material A and the thickness of the back material B, but in both cases, the surface temperature may not rise sufficiently or the foldability may deteriorate. This has disadvantages in that the cord-shaped heater H is subjected to a large tension when folded. As a countermeasure to this problem, it has been proposed to use aromatic polyamide fibers alone or in combination with glass fibers for the winding core of the cord-shaped heater, as disclosed in Japanese Utility Model Publication No. 60-9279. This idea uses aromatic polyamide fibers with high tensile strength as the winding core to reduce the diameter of the winding core.
This is a method of reducing the finished outer diameter of a cord-shaped heater. However, the aromatic fiber used for the winding core has high hygroscopicity, so when the heat-sensitive resin layer 3 is extruded after winding the metal resistor 2 around the winding core 1 in a spiral shape, moisture adheres to the winding core 1. When the heat-sensitive resin layer 3 solidifies, water foams and becomes porous, making the extrusion outer diameter of the heat-sensitive resin layer 3 unstable. It is necessary to remove moisture by putting it in a machine, which has the problem of increasing manufacturing costs. Furthermore, the cord-shaped heater H used for general electric carpets incorporates a temperature detection wire,
The temperature-impedance change of the thermosensitive resin layer 3 can be detected. As shown in FIG. 1, this thermosensitive resin layer 3 is in a state where it is constantly in contact with the highly hygroscopic winding core 1, so the moisture absorption of the thermosensitive resin layer 3 changes over time, and the desired temperature is reached. −
There were problems in that impedance change characteristics could no longer be obtained and temperature setting and temperature control methods became complicated. (Object of the invention) The present invention has been proposed in view of the above points.
The purpose of this is to omit the drying process immediately before extrusion molding of the heat-sensitive resin layer after winding the metal resistor around the winding core, and to keep the hygroscopicity of the heat-sensitive resin layer constant so that the temperature-impedance An object of the present invention is to provide a cord-shaped heater that does not change over time. Still another object is to provide a cord-shaped heater with a small finished outer diameter. (Disclosure of the Invention) A cord-shaped heater according to the present invention is a cord-shaped heater in which a metal resistor is wound around a string-shaped core made of insulating fibers, and a heat-sensitive resin layer is coated on the cord-shaped core. is a high modulus Vectran with low moisture absorption and heat resistance (product name: manufactured by Kuraray Co., Ltd.)
HNA-HBA system fully aromatic polyester called (here, HNA is 6-hydroxy-2-naphthoic acid and HBA is P-hydroxybenzoic acid).
The thermosensitive insulating layer is made of a negative characteristic plastic thermistor made by adding quaternary ammonium salt to vinyl chloride. The cord-shaped heater of the present invention uses the above-mentioned Vectran for the winding core, and has low moisture absorption and excellent heat resistance.
High modulus fibers can be obtained without drawing the spun fibers, and the thermosensitive resin layer is a negative-characteristic plastic thermistor made by adding an appropriate amount of quaternary ammonium salt to vinyl chloride, and has excellent temperature-impedance characteristics. Vectran used for the core of the cord-shaped heater of the present invention and aromatic polyamide fiber (product name: Kevlar) used for the core of the conventional cord-shaped heater
Table 1 shows a comparison of the characteristics with 49 (manufactured by DuPont, USA).

[Table] As is clear from the table, the cord-shaped heater according to the present invention has superior mechanical properties such as tensile strength, tensile elongation, and initial elastic modulus compared to conventional cord-shaped heaters. It was found that the water absorption rate was very low. It can be seen that the hygroscopicity in the present invention shows a sufficiently low water absorption rate (%) to omit the drying process required immediately before extrusion molding of the thermosensitive resin layer 3. Furthermore, when the present invention is used as a cord heater of the heat-sensitive heating element type, the temperature-impedance X of the heat-sensitive resin layer 3 does not change over time due to the hygroscopicity of the winding core 1, and the sensor function is stable. A thermosensitive heating element having the following properties is obtained. As described above, the present invention has been explained limited to the case where it is applied to a heat-sensitive heating element, but it is not limited thereto, and it may be applied to a cord-shaped heater that does not have a heat-sensitive function, for example, as shown in FIG. A cord-shaped heater or electric wire in which a metal resistor 2 made of copper alloy or the like is spirally wound around the outer periphery of a string-shaped winding core 1 with a predetermined gap, and an insulating coating layer 6 made of vinyl chloride or the like is laminated on the outermost periphery. Similar effects can also be achieved in other cases. Note that it can also be applied to electric carpets etc. in which heater wires and sensor wires are installed together. (Effects of the Invention) As described above, according to the cord-shaped heater according to the present invention, the cord is formed by wrapping a metal resistor around a string-shaped winding core made of insulating fibers, and covering the core with a thermosensitive resin layer. In the heater, the winding core is made of high modulus fibrous Vectran that has low moisture absorption and heat resistance, and the heat-sensitive insulating layer is made of a negative characteristic plastic thermistor made by adding quaternary ammonium salt to vinyl chloride. Because of this structure, it is possible to omit the drying process immediately before extrusion molding of the heat-sensitive insulating layer after winding the metal resistor around the winding core, and also to keep the hygroscopicity of the heat-sensitive insulating layer constant and to prevent temperature-impedance changes. Changes over time can be prevented.

[Brief explanation of drawings]

3 and 1 are exploded perspective views showing an example of a general cord-shaped heater, and FIG. 2 is an explanatory sectional view showing a general electric carpet. DESCRIPTION OF SYMBOLS 1... Winding core, 2... Metal resistor, 3... Heat-sensitive resin layer, 4... Heat-sensitive electrode, 5... Separation layer, 6... Insulating coating layer, A... Surface material, B... Back material , C...
Uniform heating sheet, H...cord-shaped heater.

Claims (1)

[Scope of Claims] 1. A cord-like heater in which a metal resistor is wound around a string-like core made of insulating fibers and a heat-sensitive resin layer is coated thereon, wherein the core has low moisture absorption and heat resistance. 1. A cord-shaped heater, characterized in that the heat-sensitive insulating layer is made of a negative-characteristic plastic thermistor made by adding quaternary ammonium salt to vinyl chloride.