JPH01681A - Self-temperature control heater - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a self-temperature-controllable heater, and more particularly to a self-temperature-controllable heater in which fluctuations in resistance value and operating temperature after long-term energization are minimized.

Self-temperature control heaters with a positive temperature coefficient are made by installing a resistor made of a mixture of crystalline plastic and a conductive material between a pair of electrodes, and are expected to be in increasing demand in the future as energy-saving heaters. There is.

The important point for a self-temperature control heater is that the resistance value at the reference temperature is always constant and the operating temperature does not fluctuate.

However, in conventional self-temperature control heaters, the resistance value and operating temperature fluctuate greatly due to long-term energization cycles (repeated energization and cessation of energization at a constant voltage), so something with long-term stability is desired. ing.

The present invention has been made based on the above, and aims to provide a self-temperature control heater with excellent reliability by minimizing fluctuations in resistance value and operating temperature after long-term energization. It is.

The self-temperature control heater of the present invention is characterized in that it is constructed by providing a thin adhesive layer around the outer periphery of the electrode.

Providing an adhesive layer in this way improves the adhesion between the electrode and the resistor, eliminates peeling between the electrode and the resistor even after long-term energization, and stabilizes the resistance value and operating temperature. It turns out.

The electrodes of the self-temperature control heater in the present invention include:
Common metal materials such as copper, aluminum, silver, nickel, etc. are used, and metal electrodes plated with nickel, silver, tin, etc. may also be used.

Crystalline plastics constituting the resistor include, but are not limited to, polyethylene, polypropylene, polyvinylidene fluoride, chlorinated polyethylene, polyamide, and copolymers thereof.

As the conductivity imparting material, carbon black, graphite, carbon black grafted with an organic polymer, metal powder, etc. are used.

The resistor may contain stabilizers, crosslinking aids, flame retardants, processing aids, and the like, if necessary. Further, the resistor is preferably crosslinked using an organic peroxide, electron beam irradiation, or the like.

Materials that form the thin adhesive layer include silane coupling agents, titanate coupling agents, acrylic adhesives,
Epoxy adhesives and various other primers may be used, but it is preferable to check their compatibility with the resistor material before use.

The adhesion method differs depending on the resistor material, but usually a thin layer of adhesive is applied to the electrode surface to cover the electrode, but is not limited to this method. However, if the adhesive layer is thick Since it comes to act as an insulating film, 1
It is preferable to set it to below micrometer.

Next, examples and comparative examples of the present invention will be described.

Example 1 A conductor made of 19 twisted tin-plated copper wires with an outer diameter of 0.20 mm was used as an electrode, and the surface of this electrode was thinly coated with vinyltrimethoxysilane to a thickness of 1 μm or less. Next, as shown in the attached drawings, Then, a resistor material was extruded and coated between the electrodes 1 and 2 at a temperature of 200° C. to form a resistor 4. Note that 3 is an adhesive layer, and the distance between the electrodes was 5 mm.

The thickness of the resistor 4 was 2.0 mm.

As the resistor material, low density polyethylene (density 0.9
2. Melt index 1) 100 parts by weight, carbon black (Vulcan XC-72) 15 parts by weight,
2 parts by weight of trimethylolpropane trimethacrylate,
0.2 parts by weight of 4.4'-thiobis(6-tert-butyl-3-methylphenol) was homogeneously kneaded in a Pambari mixer and then pelletized.

Thermoplastic elastomer TPR5160 was extruded and coated on the outer periphery of the resistor 4 to a thickness of 0.3 mm, and then 20 Mr.
A self-temperature-controllable heater was manufactured by irradiating and crosslinking with electron beams a and d.

The self-temperature control heater thus manufactured had a resistance value of 1.0XlO'Ω/m at room temperature, and an operating temperature of 50°C.

One cycle consists of applying GmAC100V between electrodes 1 and 2 for 1 hour and stopping the application for 10 minutes! After 000 cycles, the resistance value is 1,2XIO'Ω/m, and the operating temperature is 5
The temperature was 1°C, which was not much different from the initial value.

Example 2 A conductor made by twisting 19 silver-plated copper wires with an outer diameter of 0.20 mm was used as an electrode, and an acrylic adhesive (Acr) was applied to the surface of the electrode.
yloid B82) was thinly coated to a thickness of 1 μm or less.

As the resistor material, 100 parts by weight of polyvinylidene fluoride, 20 parts by weight of graphite (average particle size 2.5 μm),
5 parts by weight of triallyl trimellitate was homogeneously kneaded using a twin-screw extruder and then pelletized.

The configuration of the heater was the same as in Example 1, and the outer periphery of the resistor was extruded and coated with ethylene-tetrafluoroethylene copolymer to a thickness of 0.3 mm, and then crosslinked by irradiation with an electron beam of 14 Mrad.

The resistance value of the self-temperature control heater manufactured in this way at room temperature is 4.5XlO'Ω/m, and the resistance value at room temperature is 4.5
The initial operating temperature during OV power application was 95°C.

Between electrodes 1 and 2 1. :, AC200V charged for 1 hour, 10
The resistance value after repeating too many cycles, each cycle consisting of stopping power application for one minute, was 5.0×IO°Ω/m, and the operating temperature was 93° C., which did not change much from the initial value.

Comparative Example 1 A self-temperature control heater was manufactured in the same manner as in Example 1 except that a conductor not coated with vinyltrimethoxysilane was used as an electrode.

The resistance value of this self-temperature control heater at room temperature is 1.
5×10′Ω/m, and the operating temperature was 50°C.

Between electrodes 1 and 2, the resistance value after repeating 1000 cycles of applying AC1oOV for 1 hour and stopping the application for 10 minutes was 4.0XIO'Ω/m, and the operating temperature was 4.
1'C, and the change was large.

Comparative Example 2 A self-temperature control heater was manufactured in the same manner as in Example 2, except that a conductor not coated with an acrylic adhesive was used as an electrode.

The resistance value of this self-temperature control heater at room temperature is 4.
5XlσΩ/m, and the initial operating temperature when AC 200V was applied was 91'C.

After repeating 1000 cycles of applying AC200V between electrodes 1 and 2 for 1 hour and stopping the application for 10 minutes, the resistance value was 8.0XIO"97m, and the operating temperature was 82
℃, and the change was large.

Note that the resistance value was measured at room temperature using a Wheatstone bridge, and the operating temperature was measured using a thermocouple when voltage was applied.

As explained above, the present invention provides a thin adhesive layer between the electrode and the resistor, and by improving the adhesion between the electrode and the resistor, the resistance value and Fluctuations in operating temperature can be suppressed to a minimum, making it possible to realize a self-temperature control heater with excellent long-term reliability.

[Brief explanation of the drawing]

The figure is an explanatory cross-sectional view showing one embodiment of the self-temperature control heater of the present invention. l, 2: Electrode 3: Adhesive layer 4: Resistor

Claims (1)

[Claims] 1) A self-temperature-controlling heater comprising a resistor with a positive temperature coefficient made of a mixture of crystalline plastic and a conductivity-imparting material between a pair of electrodes, in which a thin adhesive layer is provided around the outer periphery of the electrodes. A self-temperature control heater characterized by: