JP3000426B2 - Polymer thermosensitive body and thermosensitive element using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polymer temperature sensing element used for a flexible temperature sensor or a temperature sensing heater such as an electric heater, and a temperature sensing element using the same.

[0002]

2. Description of the Related Art Conventionally, a polymer thermosensor is generally disposed between a pair of winding electrodes and used as a flexible linear temperature sensor or a heat-sensitive heater. Examples of the polymer thermosensitive material include nylon 12 and modified polyamide 11 (ATO-CHIM) disclosed in JP-A-55-100693.
A polyamide composition such as "Rilsan N nylon" (trade name, manufactured by IE Co., Ltd.) is used, and its temperature change such as capacitance, resistance, or impedance is used to perform a function of a temperature sensor. Also, Japanese Patent Application Laid-Open No. 58-2154
No. 49 discloses a polyamide composition in which only zinc iodide is blended into a polyamide to increase the temperature dependence of impedance. As a method for producing this polyamide composition, usually, an iodine compound as a sensitizer is dissolved in water or an organic solvent, and the solvent is mixed with polyamide pellets. To produce a polyamide composition.

[0003]

Nylon 12 is excellent in that it has a low moisture absorption rate, but is difficult to use as a temperature sensor because of its large fluctuation in temperature sensitivity due to humidity. Further, in the modified polyamide disclosed in JP-A-55-100693, the temperature dependency of impedance is small, so that the temperature detection sensitivity is low and the heat resistance stability is poor. To improve the temperature dependence of impedance, Japanese Patent Application Laid-Open No. 58-2154 discloses
In a half-wave energizing environment, the polymer thermosensitive body proposed in Japanese Patent Publication No. 49 has reduced temperature dependence of impedance due to aging, and cannot correctly detect temperature. Further, in the conventional production method, when the solvent liquid is mixed with the polyamide pellets and thermally melted, the iodine compound is decomposed in the solvent liquid, so that the iodine compound as a predetermined conductivity-imparting agent is uniformly mixed with the polyamide pellet. It was difficult to react, and it was difficult for the resulting thermosensitive body of the polyamide composition to obtain impedance-temperature characteristics (thermistor B constant) within a specified range. In addition, when using a material such as zinc oxide that does not melt in an organic solvent or a material such as zinc oxide that is difficult to melt as in the present invention, a large amount of the organic solvent is used to uniformly mix with the polyamide pellets. In addition, the working environment is significantly deteriorated, and there are many problems, such as restrictions on selection of materials to be blended.

The present invention has a large temperature dependence of impedance, a high thermistor B constant control performance, an impedance temperature characteristic which does not change from before energization even after half-wave energization, and stably maintains a predetermined impedance-temperature. It is an object of the present invention to provide a polyamide composition as a polymer thermosensor having characteristics and a thermosensor using the polymer thermosensor.

[0005]

An object of the present invention is to provide an agglomerate in which zinc iodide powder is used as base particles and child particles made of zinc oxide fine powder are adhered around the base particles to form an agglomerate. A thermosensitive polymer having a polyamide composition in which zinc oxide powder is used as mother particles, and aggregates obtained by adhering and agglomerating child particles made of zinc iodide fine powder around the mother particles are mixed with polyamide. It is a body and a thermosensitive element using the same.

[0006]

Generally, a polymer thermosensitive element is disposed between a pair of copper or copper alloy winding electrodes and used as a flexible linear temperature sensor or thermal heater. The impedance-temperature dependency of these temperature sensors and thermal heaters is determined by the stability of the polymer thermosensor itself and the surface condition of the winding electrode. When the above-mentioned polyamide composition is used, the temperature dependence of impedance is significantly increased due to the ion carrier property of zinc iodide in the polymer thermosensor, and a zinc complex is formed on the amide group to increase the current-carrying stability. It is also thermally stable. However, while iodine generated from zinc iodide when used for a long time at high temperature is localized around the amide group, it acts on the metal electrode as iodine ion to generate metal iodide which is an electrical insulator, Impairs the stability of the impedance between the electrodes. For example, if copper is used for the electrode,
Copper iodide is generated, and it is difficult to obtain stability over time of the impedance between electrodes. Therefore, when zinc oxide is used in combination, the zinc oxide acts as an iodine ion acceptor and can prevent the generation of iodine metal on the surface of the metal electrode. Further, it is considered that the zinc oxide forms zinc iodide, and an interlocking cycle in which the effect of improving the current-carrying stability works. Therefore, the impedance-temperature characteristics of the polymer thermosensor are improved, and the temperature-sensitivity of the polymer thermosensor is not impaired even in a half-wave energized state, and the stability of the impedance-temperature characteristics as a temperature sensor or a thermal heater is improved. Can be significantly increased. In addition, since an agglomerate obtained by adhering zinc oxide powder to zinc iodide powder is used, in the heat melting process associated with a twin-screw extrusion kneader, etc., the above-described inter-ring cycle for improving the electric conduction stability is efficient. It is possible to easily carry out a mixing reaction with the polyamide while acting well.

Further, a strong moisture absorption preventing effect can be imparted by blending an aldehyde polycondensate of a phenol compound. Phenolic compounds have good compatibility with polyamides, and coordinate with hydrogen bonding sites in polyamide instead of water molecules to reduce hygroscopicity and reduce fluctuations in temperature-sensitive characteristics due to humidity. There is also an effect of increasing the temperature sensitivity by acting on the amide group.

Further, when noble metals such as gold, platinum and palladium are used as the electrode material, and when a plating is applied, the formation of metal iodide is hardly observed, but silver,
When tin, solder, stainless steel, titanium, indium, or the like is used, since the iodide of these metals has relatively high conductivity, the temporal stability of the impedance between the electrodes can be improved.

[0009]

An embodiment of the present invention will be described below. In the present embodiment, as the polyamide, nylon 12, nylon 12-nylon 40 copolymer, N-
Alkyl-substituted polyamide 11, polyetheramide, and dimer acid-containing amide were selected. Zinc iodide having high thermal stability was used as a conductivity-imparting agent for increasing the temperature dependence of the impedance of these polymers. Zinc oxide powder was used as the iodine receptor. Further, in the example in which an aldehyde polycondensate of a phenol compound was added, an octyl oxybenzoate-formaldehyde polycondensate having good compatibility with polyamide was selected to have 15 parts by weight.

FIG. 1 illustrates the production process of a main part of an embodiment of a polyamide composition as a polymer thermosensitive material according to the present invention. As shown in FIG. 1, first, as shown in FIG. A particle diameter of 0.1 to 0.5 μ around the base particles 1 of zinc powder
A plurality of sub-particles 2 made of m. zinc oxide powder are adhered by an electrostatic method, a mechanical method, or the like to form an aggregate 3 that covers and aggregates the base particles 1. Next, the aggregate 3 and the above-described polyamide powder 4 having a particle diameter of about several tens to 100 μm are mixed using a Hensyl mixer or the like so as to be uniform. These were melt-mixed by a twin-screw extruder and injection-molded to produce a polyamide composition. The polyamide composition thus produced was formed into a sheet having a thickness of about 70 × 70 mm and a thickness of 1 mm by a hot press, and silver-coated electrodes were provided on both surfaces of the sheet. Also,
Dependence on electrode material is silver plating on silver plate, gold plate, and copper plate,
Tin-plated and solder-plated ones were used. The temperature dependence of the impedance was represented by the thermistor B constant at 40 to 80 ° C.

Regarding the sheet piece molded by the above method,
Sheet pieces molded with a polyamide composition obtained by simply mixing zinc iodide powder and zinc oxide powder with a conventional polyamide, and sheet pieces molded with the polyamide resin of the present invention,
B constants were calculated for each of 100 sheets, and variations in the calculated B constants were compared. Deterioration due to half-wave energization was represented by a temperature difference (ΔT _z ) between the initial impedance at 100 ° C. and the impedance at 100 ° C. after 100-hour half-wave energization at 100 ° C. for 1000 hours. 40 to 8
The thermistor B constant at 0 ° C. is the impedance Z _{40 at} 40 ° C. and the impedance Z _{80 at} 80 ° C.
Was calculated based on the measurement results.

The results are shown in Tables 1 and 2.

[0013]

[Table 1]

[0014]

[Table 2]

Similarly, FIG. 2 shows a process of manufacturing a main part of another embodiment of a polyamide composition as a polymer thermosensitive material according to the present invention. In FIG. 2, the particle diameter is several tens to 30.
A plurality of zinc iodide powder child particles 6 as a conductivity-imparting agent were adhered to the periphery of the μm zinc oxide powder base particles 5 by an electrostatic method, a mechanical method, or the like, and the base particles 5 were coated and agglomerated. Aggregates 7 are constituted. Next, this aggregate 7
The above-described polyamide powder 4 having a particle size of about several tens to 100 μm is mixed with a Hensyl mixer or the like so as to be uniform.

These were kneaded with a twin-screw extruder to produce a polyamide composition. Using this polyamide composition, the results of comparison of various properties by the same test method as described above are shown in Tables 3 and 4. Shown in

[0017]

[Table 3]

[0018]

[Table 4]

As can be seen from Tables 1, 2 and 3 and 4, as the sensitizer of the present invention, zinc iodide anhydride or zinc iodide dihydrate is used, which contributes to the improvement of the thermistor B constant. I have. Zinc iodide is present in the polyamide in an amount of 0.01 to 3
0 parts by weight are blended. If the amount is less than 0.01 part by weight, the sensitizing property and the half-wave current stabilizing effect are low, and if it is more than 30 parts by weight, the physical properties of the composition are significantly impaired. In addition, when used at a high temperature for a long period of time, zinc oxide is used as a receptor for iodide ions generated from zinc iodide, which contributes to prevention of generation of metal iodide on the surface of a metal electrode. further,
The zinc oxide forms zinc iodide and acts to improve the current-carrying stability, thereby functioning as an interlocking cycle. In addition, the B constant of the polymer thermosensor of the present invention has a small variation and a predetermined value stably compared to the B constant of the conventional polymer thermosensor because the above-described connected ring cycle works efficiently. The B constant is obtained. Accordingly, it is possible to improve the control of the B constant and the half-wave energizing stability of the polymer thermosensitive body, and to remarkably increase the temperature sensing characteristics and the half-wave energizing stability as a temperature sensor thermal heater. Zinc oxide has a low effect if it is less than 0.01 parts by weight, which is added to the polyamide in an amount of 0.01 to 30 parts by weight.
If it exceeds 0 parts by weight, the physical properties of the composition are significantly impaired.

As can be seen from the B-constant characteristics in Tables 1 to 4, the particle diameters of the above-mentioned child particles and base particles, and their blending amounts can be easily set. Can be finely tuned.

In the case of adding a phenol compound, the aldehyde polycondensate of a phenol compound having good compatibility with polyamide includes octyl p-oxybenzoate-aldehyde polycondensate and iso-p-oxybenzoate. Sterial ester-formaldehyde polycondensate is excellent in compatibility and moisture resistance, but in addition to p-oxybenzoic acid alkyl ester, p-dodecylphenol, p-chlorophenol, p-oxybenzoic acid nonyl ester, etc. It may be an aldehyde polycondensate. These are blended in the polyamide in an amount of 5 to 30 parts by weight. If the amount is less than 5 parts by weight, the effect is low, and if it is more than 30 parts by weight, the properties of the composition are significantly impaired.

Nylon 12 (10
0 parts by weight), zinc iodide (5.5 parts by weight), zinc oxide (4.0 parts by weight), and a pellet of a nylon compound, and using the pellets, a thermosensitive element as shown in FIG. That is, a temperature detection line was created. Here, each component will be described. 8 is a 1500 denier polyester core yarn, 9 and 11 are 0.5% silver-containing copper electrode wires, 10 is a nylon thermosensitive layer according to the present invention, 12 is a polyester separating layer, 13 Is a heat-resistant polyvinyl chloride jacket. For the purpose of comparison, the thermistor B constant was about 3.3 times that of a trial product in which a thermosensitive layer was formed using only nylon 12 at 11600 (K).
And a durability of 3000 hours or more against continuous 100 V half-wave conduction at 100 ° C. performed as a heat resistance life test.

Further, about 30 μm
In the case of using an electrode wire plated with solder of 95% of tin and 5% of lead, a durability of 5000 hours or more was exhibited.

[0024]

According to the present invention, the following effects can be obtained. (1) An aggregate obtained by adhering zinc oxide around zinc iodide, or an aggregate obtained by adhering zinc iodide around zinc oxide is mixed with polyamide. Since it can be reacted with polyamide efficiently, the B constant value of the thermistor can be improved, the variation of the B constant value can be reduced, and even at high temperatures, the electrical characteristics over a long period of time can be stabilized. Reliability can be improved. (2) The impedance-temperature dependency (thermistor B constant) of the polymer thermosensitive body can be finely set by arbitrarily changing the materials and blending amounts of the child particles and the base particles. (3) Since no organic solvent or the like is used at the time of mixing, the working environment does not deteriorate during the kneading process.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a manufacturing process of a main part of a polymer thermosensor in one embodiment of the present invention.

FIG. 2 is an explanatory view of a manufacturing process of a main part of a polymer thermosensor in another embodiment of the present invention.

FIG. 3 is a partially cutaway side view of a temperature detecting heater wire using the temperature sensing element of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Zinc iodide powder base particle 2 Zinc oxide powder core particle 3, 7 Aggregate 4 Polyamide powder 5 Zinc oxide powder base particle 6 Zinc iodide powder core particle 8 Polyester core thread 9, 11 0.5% silver-containing copper electrode wire 10 Nylon thermosensitive layer 12 Polyester separating layer 13 Polyvinyl chloride jacket

Continuation of the front page (56) References JP-A-58-215449 (JP, A) JP-A-4-103659 (JP, A) JP-A-6-151112 (JP, A) JP-A-61-260607 (JP) , A) JP-A-5-234497 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01C ^7/ 02-7/22

Claims (8)

(57) [Claims] 1. A polyamide composition comprising zinc iodide powder as base particles, and agglomerates formed by adhering and agglomerating child particles made of zinc oxide fine powder around the base particles and blending the aggregates with polyamide. Polymer thermosensor. 2. A polyamide composition comprising zinc oxide powder as mother particles, and agglomerates formed by adhering and agglomerating child particles made of fine zinc iodide powder around the mother particles and blending the aggregates with polyamide. Polymer thermosensor. 3. The polymer thermosensor according to claim 1, wherein the zinc iodide is at least one selected from zinc iodide anhydrate and zinc iodide hydrate. 4. The polyamide composition according to claim 1, further comprising an oxybenzoate-formaldehyde polycondensate.
Or the polymer thermosensitive body according to 2. 5. The polyamide comprises the following (a) to (f):
At least one member selected from the group consisting of:
Or the polymer thermosensitive body according to 2. (A) Polyundecaneamide (b) Polydodecaneamide (c) Polyamide containing straight-chain saturated hydrocarbon having 13 or more carbon atoms or a copolymer thereof (d) Polyundecaneamide or N-alkyl-substituted amide of polydodecaneamide Copolymer (e) Polyundecaneamide or etheramide copolymer of polydodecaneamide (f) Dimer acid-containing polyamide 6. A thermosensitive element comprising the polymer thermosensitive element according to claim 1 disposed between a pair of electrodes. 7. As one of the pair of electrodes or one or both electrodes, gold, platinum, palladium,
7. The temperature-sensitive element according to claim 6, wherein a metal selected from the group consisting of silver, tin, solder, stainless steel, titanium, and indium is used. 8. The method of claim 1, wherein one of the pair of electrodes or the surface layer of both the electrodes is formed of gold, platinum, palladium, silver,
7. The temperature-sensitive element according to claim 6, wherein the metal is selected from the group consisting of tin, solder, titanium, and indium.