JPS58106787A - Self-temperature controllable 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 control heater.

Conventional self-temperature control heaters are constructed by coating electrodes with a resistor composition having a positive temperature coefficient of resistance (PTI characteristic).This composition is composed of a crystalline polymer and a conductivity imparting material. Therefore, in order to maintain the PTC characteristics, the amount of conductivity imparting material needs to be in a relatively small area.

However, compositions in this range have the disadvantage that their resistance values tend to fluctuate depending on manufacturing conditions and usage conditions. In particular, the resistance value tends to change depending on the voltage or due to long-term power application cycles, resulting in a lack of long-term reliability. These are mainly caused by insufficient adhesion between the electrode and the resistor composition interface. Although the adhesion of the interface can be improved by changing the composition, extrusion conditions, heat treatment conditions, etc., there is a concern that if some unstable parts occur locally, the function as a self-temperature-controlling heater may become insufficient. .

A method of coating the electrode interface with an adhesive may be considered, but this is effective in providing stability during the charging cycle, but since the adhesive is usually an insulator, the coating thickness must be controlled below a certain value. Fluctuations in resistance value occur due to voltage. It was found that those whose resistance value fluctuates with voltage generally lack stability over long-term energization cycles.

In addition, in order to improve the stability due to the charging cycle,
As described above, it is effective to improve the adhesion between the electrode and the resistor composition, but the conventional techniques become an obstacle when it is necessary to peel off the resistor, such as in terminal construction or connection work.

If the stability of charging is emphasized in this way, the workability of stripping the electrode from the electrode must be sacrificed to some extent. On the other hand, if the stripping workability was made easier, there was a concern that the stability of power application would be lacking.

Therefore, if we can provide a self-temperature-controlling heater that has excellent power application stability and is easy to work with when stripping the resistor from the electrode, we believe that it will make an extremely large contribution to industry.

The object of the present invention is to eliminate the drawbacks of the prior art mentioned above, to reduce the variation in resistance value due to voltage, to reduce the variation in resistance value even in long-term energizing cycles, and to reduce the workability of stripping the resistor from the electrode. An object of the present invention is to provide a heater with excellent self-temperature control.

In other words, the gist of the present invention is to provide a layer between the electrode and the resistor having a positive temperature coefficient of resistance, which has a lower volume resistivity than the resistor and has good adhesion to the resistor. At the point.

The electrode is made of metal such as copper, aluminum, nickel, silver, or tin, or carbon fiber. It may be a plated metal, taking into consideration the type of resistor and usage conditions.

A resistor composition having a positive temperature coefficient of resistance is composed of a combination of a crystalline plastic and a conductivity imparting material. Crystalline plastics are plastics that have crystals, and include polyethylene, ethylene copolymers such as ethylene-vinyl acetate copolymers, ethylene-propylene copolymers, polypropylene, polypentene-1, polymethylpentene-1, and polyfluoride. Examples include, but are not limited to, vinylidene, ethylene-tetrafluoroethylene copolymer, chlorinated polyethylene, polyester, and polyamide.

These crystalline plastics can be used alone or in combination of two or more. Further, rubber such as ethylene-propylene rubber, chlorosulfonated polyethylene rubber, fluororubber, silicone rubber, etc. may be mixed with the crystalline plastic.

Examples of conductivity-imparting materials include carbon black, graphite, metal powder, and carbon black obtained by grafting organic polymers. These may be used alone or in combination of two or more.

In addition to crystalline plastics and conductivity imparting materials, antioxidants,
It may contain stabilizers, lubricants, surfactants, reactive monomers, organic peroxides, etc. Further, the present resistor composition may be used as it is, or may be crosslinked by chemical crosslinking, electron beam irradiation crosslinking, silane craft water crosslinking method, or the like.

The low-resistance binder layer of the present invention includes (1) a composition in which the same polymer as the resistor composition is used and a conductivity-imparting material is added in a larger amount than in the resistor composition; (2) a composition in which the same polymer as the resistor composition is added; A composition using a polymer with excellent adhesion to the resin and adding a conductivity imparting material. For example, polyethylene as the polymer for the resistor composition, ethylene copolymer, ethylene-propylene copolymer, ethylene-propylene rubber, etc. as the binder layer. (6) A composition in which a conductivity-imparting material is added to the adhesive for the polymer of the resistor composition, etc., but the composition is not limited to these as long as it can impart adhesiveness to the resistor. stomach.

The resistance value of the binder layer varies depending on the resistance value of the resistor, but preferably the volume resistivity of the binder layer is 1 that of the resistor.
/100 or less, excellent effects were obtained.

It has been found that the closer the difference in resistance values between the two is than this value, the less effective it becomes.

Methods for applying the binder layer include painting, extrusion coating, and the like.

Further, it is desirable that the temperature coefficient of resistance of the binder layer is as small as possible below the operating temperature of the heater. In other words, the temperature coefficient is negative or has a positive value of zero or close to zero. It has been found that in the case of a binder layer having such properties, the difference between the resistance value of the resistor and the resistance value of the binder layer becomes larger at operating temperature than at room temperature, and the effect of the present invention becomes even greater. .

Such properties can be achieved by appropriately selecting the properties of the polymer (melting point, degree of crystallinity, molecular weight, specific volume-temperature properties, etc.), the type and amount of the conductivity imparting material, etc.

Examples of the present invention will be described.

Example 1 Polyethylene (density a = 0.92, melting index M = 1)
100 parts by weight, 20 parts by weight of acetylene black, 4.4
For a resistor composition in which 0.2 parts by weight of '-thiobis(6-tert-butyl-6-methylphenol) and 1 part by weight of trimethylolpropane trimethacrine were evenly mixed, ethylene-ethyl Acrylate copolymer (ethyl acrylate amount = 20%
, M = 15) 100 parts by weight, acetylene black 40
Parts by weight, 4.4'-thiobis(6-tert-butyl-
A low-resistance binder layer composition in which 0.3 parts by weight of 6-methylphenol was uniformly mixed was used.

As shown in Fig. 1, the low-resistance binder layer composition described above is placed on each circumference of two conductor electrodes 1.1' (5 questions of distance between conductors) made by twisting 19 tin-plated wires with an outer diameter of 0.20y+o++. Binder layer of the object 2. Then, a resistor 6 of the above-described resistor composition was coated by extrusion to a thickness of 0.3 mm.
was extrusion coated to a thickness of 2fi. Furthermore, an insulator 4 made of thermoplastic elastomer TPR5190 (manufactured by 22 Royal Company, USA) was extruded and coated thereon to a thickness of 0.3 mm, and irradiated with an electron beam of 20 Mrad.

The volume resistivity of the resistor was 1×10'Ω-1, and the volume resistivity of the binder layer was 2×102Ω-.

Example 2.

100 parts by weight of polyvinylidene fluoride, graphite KS
2,5 is 20 parts by weight inopropyl (triinstearyl) titanate 0.゛1 part by weight, triallyl) To a resistor composition in which 5 parts by weight of IJ Melitate was uniformly kneaded, a binder layer composition in which 40 parts by weight of only the graphite in this composition was added was added in dimethylacetamide. A solution was prepared so that the solid content was 50%.

Two conductor electrodes (distance between conductors: 5fi) made by twisting 19 nickel-plated wires with an outer diameter of 0.20 ttan were coated with the above solution to a thickness of Q, 1 mm, and infrared rays were applied. It was heated in a heating furnace until the solvent was scattered. Next, a resistor of the above-mentioned resistor composition was formed to a thickness of 2f.
It was extrusion coated to a thickness of III11.

Furthermore, an insulator made of ethylene-tetrafluoroethylene copolymer was extruded and coated on top of it to a thickness of 0.66 mm.
It was irradiated with a rad electron beam.

The volume resistivity of the resistor was 5×10 4 Ω-α, and the volume resistivity of the binder layer was I×10” Ω-α.

Example 3 For the same resistor composition as in Example 1, polyethylene (
a = 0.92, M engineering = 10) 100 parts by weight, graphite (average particle size = 1μ) 50 parts by weight, 4.4'-thiobis(6-tert-butyl-6-methylphenol) 0
．． A binder layer composition consisting of 2 parts by weight of trimethylolpropane trimethacrylate and 3 parts by weight of trimethylolpropane trimethacrylate was used. Everything else is the same as in Example 1.

The resistance value of the binder layer composition below the operating temperature is (20°C) 1.0×10”Ω-α, (30°C) 1.
I
A1 (50℃) 1.5 x 10”Ω- (60℃
) 1.7 x 108 Ω-, and has an extremely small positive temperature coefficient of resistance.

Comparative Example 1 Same as Example 1 except that the binder layer of Example 1 was not applied.

Comparative Example 2 Same as Example 2 except that the binder layer of Example 2 was not applied.

Comparative Example 3 The binder layer composition was ethylene-ethyl acrylate copolymer (ethyl acrylate amount = 20, MI = 1
5) 100 parts by weight, 30 parts by weight of acetylene black, 4
, 0.6 parts by weight of 4'-thiobis(6-tert-butyl-3-methylphenol). Other than that, Example 1
is the same as

The volume resistivity of the resistor was I.times.10'.OMEGA., and the volume resistivity of the binder layer was 1.times.10'.OMEGA.

Table 1 shows the characteristics measurement results for each side described above.

The measurement method for each characteristic item is as follows.

- Volume resistivity: A sheet sample with a thickness of 1 WrIn was prepared from the resistor and binder layer composition on each side, and the resistance value was measured with a Wheatstone bridge and converted to volume resistivity.

・Resistance value-voltage dependence: Using a circuit as shown in Figure 2, apply a DC voltage of 200 V between the electrodes Fl and 51' of the heater 5 on each side by varying the voltage with the voltage regulator B, and apply the ammeter 7, The value of the voltmeter 8 was read and the resistance value was calculated.

- Heat generation temperature: Attach a dielectric couple to the surface of the resistor of the heater on each side, and read the heat generation temperature when an AC voltage of 200 cm is applied between the electrodes.

・Electrification cycle: Current voltage 20 between the electrodes of the heater on each side
0■ is charged for 1 hour, and then stopped for 10 minutes. This is 1
Repeated as a cycle.

The heat generation temperature and resistance value were measured after 2000 cycles.

- Peeling workability Evaluation was made based on the ease of work when stripping the resistor from the electrode using two nippers.

In the heater of the present invention, a binder layer having a lower volume resistivity than the resistor is interposed between the electrode and the resistor, so problems caused by insufficient adhesion between the electrode and the resistor can be solved. , has excellent long-term charging cycle stability.

Furthermore, since the binder layer is integrated with the resistor, it can be easily peeled off at the interface between the electrode and the binder layer. This is because the adhesiveness of the binder layer to the resistor is superior to that to the electrode.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of the self-temperature control heater of the present invention. FIG. 2 is a wiring diagram of the resistance value-voltage dependence measuring circuit. 1.1': conductor electrode, 2. Kunino<inder layer, 6: resistor, 4: insulator. Agent Patent Attorney Fujio Sato No. 1 Surface volume resistivity Electrification cycle resistance value voltage dependence 〒 1 CoT 2 n 51' Procedural amendment C method) % formula % 2 Name of the invention Self-temperature control heater a Representative of the person making the amendment Representative Person 〒100 Subject of amendment (1) Detailed explanation of the invention in the specification. (2) A brief explanation of the drawings in the specification. Correct. Attachment: Attachment: Read the fever temperature when one or more documents are sent. Charging cycle: 200 AC voltage between electrodes of heater on each side
Voltage is applied to v for 1 hour and then stopped for 10 minutes. This was repeated as one cycle. The heat generation temperature and resistance value were measured after 2000 cycles. Stripping workability: Judgment was made based on the ease of stripping the resistor from the electrode using nippers. In the heater of the present invention, a binder layer having a lower volume resistivity than the resistor is interposed between the electrode and the resistor, so the problem caused by insufficient adhesion between the electrode and the resistor is solved. It has excellent long-term charging cycle stability. Furthermore, since the binder layer is integrated with the resistor, it can be easily peeled off at the interface between the electrode and the binder layer. This is because the adhesion of the binder layer to the resistor is superior to that of the electrode. Table 1 FIG. 1 is a sectional view showing an embodiment of the self-temperature control heater of the present invention. FIG. 2 is a wiring diagram of the resistance value-voltage dependence measuring circuit. 1, i': conductor electrode, 2, 2: binder layer, 6: resistor, 4: insulator.

Claims (1)

[Claims] 1. A self-temperature-controlling heater comprising a resistor made of crystalline plastic and a conductivity-imparting material and having a positive temperature coefficient of resistance, and an electrode in electrical contact with the resistor; A self-temperature control device characterized in that a binder layer is provided between the resistor and the binder layer, which has a lower volume resistivity than the resistor and whose adhesiveness to the resistor is superior to the adhesiveness to the electrode. Sex heater. 2. The self-temperature control heater according to claim 1, wherein the volume resistivity of the binder layer is 1/100 or less of the volume resistivity of the resistor. 6. The self-temperature control property according to claim 1, wherein the temperature coefficient of resistance of the binder layer is an extremely small value near zero below the operating temperature of the heater.