JP3000425B2 - 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 thermosensor used for a flexible temperature sensor or a heat sensor such as an electric heater, and a thermosensor using the polymer thermosensor.

[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. Furthermore, Japanese Patent Publication No. 3-50401 proposes a composition containing an aldehyde polycondensate of a phenolic compound. Also, Japanese Patent Laid-Open No.
Japanese Patent No. 215449 discloses a polyamide composition in which only an iodine compound (zinc iodide) is blended with a polyamide as a conductivity-imparting agent to increase the temperature dependence of impedance.

[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. Therefore, in order to improve humidity resistance and temperature sensitivity, there has been proposed a composition containing an aldehyde polycondensate of a phenolic compound as disclosed in Japanese Patent Publication No. 3-50401. However, all of these have problems such as low temperature dependence of impedance and insufficient thermal stability over a long period of time. In the polymer thermosensor disclosed in JP-A-58-215449 for the purpose of increasing the temperature dependence of the impedance, the impedance-temperature characteristics change with time under a half-wave energizing environment, Temperature dependence of impedance is smaller than before half-wave conduction,
There were problems that the temperature could not be detected correctly and that the heat-resistant mechanical strength also decreased.

[0004] The present invention relates to a polymer thermosensitive element having a large temperature dependence of impedance, having stable impedance-temperature characteristics even after half-wave energization, and having excellent thermal stability, and a thermosensitive element using the same. The purpose is to provide.

[0005]

According to the present invention, a composition comprising polyamide and cadmium iodide and cadmium oxide is used as a thermosensitive body.

In the present invention, a composition obtained by mixing at least one selected from hindered phenol and naphthylamine with a composition obtained by mixing cadmium iodide and cadmium oxide with a polyamide is used as a thermosensitive body.

[0007]

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 heat stability of these temperature sensors and heat-sensitive 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 remarkably increased due to the ion carrier property of cadmium iodide in the polymer thermosensor, and a cadmium complex is formed on the amide group to increase the current-carrying stability. It is also thermally stable. However, iodine generated from cadmium iodide when used for a long time at high temperature is localized around the amide group, while acting on the metal electrode as iodine ion to generate metal iodide as an electrical insulator, Impairs the stability of the impedance between the electrodes. For example, when copper is used for the electrode, copper iodide is generated, and it is difficult to obtain the temporal stability of the impedance between the electrodes. Therefore, when cadmium oxide is used together, cadmium oxide acts as a receptor for iodine ions,
Generation of iodine metal on the surface of the metal electrode can be prevented. Furthermore, the cadmium oxide produces cadmium iodide, and the function of improving the current-carrying stability works to form a continuous ring cycle. Therefore, the thermal stability of the polymer thermosensitive body can be improved, and the heat resistance stability as a temperature sensor or a thermosensitive heater can be significantly increased. Further, by blending an aldehyde polycondensate of a phenol compound, a strong moisture absorption preventing action can be imparted. 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. Moreover, due to the antioxidant properties of hindered phenol or naphthylamine,
It becomes thermally stable. Combinations of cadmium iodide and cadmium oxide and hindered phenol or naphthylamine as in the present invention are not excluded from each other even if their actions overlap, but have a synergistic action when added. Therefore, the thermal stability of the polymer thermosensitive body is improved, and the heat resistance stability as a temperature sensor or a thermosensitive heater is remarkably increased.
In addition, for example, when the electrode material uses a noble metal such as gold, platinum, or palladium, or when plating is applied, generation of a metal iodide is hardly observed, but silver, tin, solder, stainless steel, titanium, When using indium or the like, these metal iodides have relatively high conductivity,
The temporal stability of the impedance between the electrodes can be improved.

[0008]

Embodiments of the present invention will be described below. In this example, as the polyamide, nylon 12, nylon 12-nylon 40 copolymer, N-alkyl-substituted polyamide 11, polyetheramide, and amide containing dimer acid were selected. Cadmium iodide having high thermal stability was used as a conductivity-imparting agent for increasing the temperature dependence of the impedance of these polymers. Cadmium oxide powder having a particle diameter of 0.1 to 0.5 μm was used as the iodine receptor. Further, in the case where an aldehyde polycondensate of a phenol compound was added, an octyl oxybenzoate / formaldehyde polycondensate having good compatibility with polyamide was selected to be 15 parts by weight. After mixing these samples and kneading them with an extruder, the sample was heated to about 70 ×
The sheet was formed into a sheet having a thickness of 70 mm and a thickness of 1 mm. In addition, electrode material dependence is silver plating, tin plating, silver plating, gold plating, and copper plating.
The one subjected to solder plating was used. The temperature dependence of the impedance was represented by the thermistor B constant at 40 to 80 ° C. In addition, the thermal stability is such that the initial impedance at 100 ° C. and the half-wave current of 100 V at 100 ° C.
It was represented by a temperature difference (ΔT _z ) from the impedance at 100 ° C. after performing for 00 hours. The thermistor B constant at 40 to 80 ° C. is the impedance Z _{40 at} 40 ° C.
And the impedance Z ₈₀ at 80 ° C. was calculated.

The results are shown in (Table 1) and (Table 2).

[0010]

[Table 1]

[0011]

[Table 2]

Next, another embodiment of the present invention will be described.
In Examples, as the polyamide, nylon 12, nylon 12-nylon 40 copolymer, N-
Alkyl-substituted polyamide 11, polyetheramide, and dimer acid-containing amide were selected. Cadmium iodide having high thermal stability was used as a conductivity-imparting agent for increasing the temperature dependence of the impedance of these polymers. Cadmium oxide powder having a particle diameter of 0.1 to 0.5 μm was used as the iodine receptor. Further, in order to enhance antioxidant properties and thermal stability, triethylene glycol-bis [3- (3-t-butyl-5-methyl-) is used as a hindered phenol.
4-hydroxyphenyl) propionate (having a molecular weight of 5
86.8), pentaerythrityl-tetrakis [3-
(3,5-di-t-butyl-4-hydroxyphenyl)
Propionate (1177.7 molecular weight), N, N'-
Hexamethylene bis (3,5-di-t-butyl-4-hydroxy-hydroxy namamide) and (having a molecular weight of 63
7.0), 3,9-bis {2- [3- (3-t-butyl-4-hydroxy-5-methylphenyl) propionyloxy] -1,1-dimethylethyl} -2,4,8, 1
0-tetraoxaspiro [5,5] undecane (molecular weight: 741) was selected, and phenyl-α-naphthylamine (molecular weight: 404) was selected as naphthylamine.
Further, in the example where an aldehyde polycondensate of a phenol compound was added, an octyl oxybenzoate / formaldehyde polycondensate having good compatibility with polyamide was selected.
Parts by weight were used. The sample was compounded, kneaded by an extruder, and then heated to about 70 × 70 mm and 1 m thick.
m and a silver-coated electrode was provided on both sides of the sheet. The electrode material dependence was determined by using a silver plate, a gold plate, and a copper plate which were subjected to silver plating, tin plating, and solder plating. The temperature dependence of the impedance is 40 to 8
Expressed as a thermistor B constant at 0 ° C. The heat stability was evaluated by performing an air heating aging test at 120 ° C. on a dumbbell test piece and evaluating the time at which the strength at the yield point was reduced by half. Furthermore, the initial impedance at 100 ° C.
And the temperature difference (ΔT _z ) from the impedance after 100-hour half-wave conduction for 500 hours. The thermistor B constant at 40 to 80 ° C. is the impedance Z _{40 at} 40 ° C. and the impedance Z at 80 ° C.
₈₀ was calculated based on the measurement results.

The results are shown in (Table 3) and (Table 4).

[0014]

[Table 3]

[0015]

[Table 4]

Cadmium iodide anhydride or cadmium iodide dihydrate is used as the sensitizer of the present invention, which contributes to the improvement of the thermistor B constant. These are blended in an amount of 0.01 to 30 parts by weight based on the polyamide.
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. Cadmium oxide is used as a receptor for iodine ions generated from cadmium iodide when used at a high temperature for a long period of time, which contributes to prevention of generation of metal iodide on the surface of a metal electrode. In addition, the cadmium oxide forms cadmium iodide and acts to improve the current-carrying stability. Therefore, the thermal stability of the polymer thermosensitive body can be improved, and the heat resistance stability as a temperature sensor or a thermosensitive heater can be significantly increased. These are blended in an amount of 0.01 to 30 parts by weight based on the polyamide. If the amount is less than 0.01 part by weight, the effect is low, and if it is more than 30 parts by weight, the physical properties of the composition are significantly impaired.

As an antioxidant, triethylene glycol-bis [3- (3-t) is used as a hindered phenol.
-Butyl-5-methyl-4-hydroxyphenyl) propionate] or pentaerythrityl-tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] or N, N'-hexamethylenebis (3,5-di-t-butyl-4-hydroxy-hydroxy namamide) or 3,9-bis {2- [3-
(3-t-butyl-4-hydroxy-5-methylphenyl) propionyloxy] -1,1-dimethylethyl
-2,4,8,10-Tetraoxaspiro [5,5] undecane and naphthylamine are used and contribute to improvement of heat resistance. These combinations exert a further synergistic effect.

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. The stearyl 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), pellets of a nylon compound comprising cadmium iodide (4.0 parts by weight) and cadmium oxide (3.0 parts by weight), and using the pellets, a temperature-sensitive element as shown in FIG. That is, a temperature detection line was created. Here, each component will be described. 1 is a 1500 denier polyester core yarn, 2, 4 is a 0.5% silver-containing copper electrode wire, 3 is a nylon thermosensitive layer, 5 is a polyester separating layer, 6
Is a heat-resistant polyvinyl chloride jacket. For the purpose of comparison, the thermistor B constant was about 3.3 times 11600 (K), which was about 3.3 times higher than that of a trial product in which a thermosensitive layer was formed only with nylon 12, and continuous 100 V at 100 ° C., which was performed as a heat resistance life test.
This showed a durability of 3000 hours or more against half-wave energization.

When a 0.5% silver-containing copper electrode wire was plated with about 30 μm of tin 95% -lead 5% solder, an endurance of 5000 hours or more was obtained.

[0021]

As described above, according to the present invention, the combined use of cadmium iodide and cadmium oxide and the combined use of hindered phenol or naphthylamine can improve the thermistor B constant and provide a long-lasting machine even at high temperatures. By stabilizing the mechanical strength and electrical characteristics, the reliability of many practical applications can be improved.

[Brief description of the drawings]

FIG. 1 is a partially cutaway side view of a temperature detecting heater wire using a temperature sensing element according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Polyester core thread 2, 4 0.5% silver containing copper electrode wire 3 Nylon thermosensitive layer 5 Polyester separation layer 6 Polyvinyl chloride jacket

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01C ^7/ 02-7/22

Claims (16)

(57) [Claims] 1. A polymer thermosensor comprising a polyamide composition comprising polyamide and at least cadmium iodide and cadmium oxide. 2. The polymer thermosensor according to claim 1, wherein the cadmium iodide is at least one selected from cadmium iodide anhydrate and cadmium iodide hydrate. 3. The polymer thermosensor according to claim 1, wherein the polyamide composition has an oxybenzoate / formaldehyde polycondensate. 4. The polyamide comprises the following (a) to (f):
At least one member selected from the group consisting of:
The polymer thermosensitive body according to the above. (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 5. A thermosensitive element comprising the polymer thermosensitive element according to claim 1 disposed between a pair of electrodes. 6. A material for one or both electrodes of the pair of electrodes, which is gold, platinum, palladium,
The temperature-sensitive element according to claim 5, wherein a metal selected from the group consisting of silver, tin, solder, stainless steel, titanium, and indium is used. 7. An electrode in which one or both electrodes of a pair of electrodes are plated with a metal selected from the group consisting of gold, platinum, palladium, silver, tin, solder, titanium, nickel, and indium. 6. The thermosensitive element according to claim 5, wherein the thermosensitive element is a clad electrode. 8. A polymer thermosensor having a polyamide composition obtained by mixing at least cadmium iodide and cadmium oxide with polyamide and further mixing at least one selected from hindered phenol and naphthylamine. 9. The polymer thermosensitive body according to claim 8, wherein the cadmium iodide is at least one selected from cadmium iodide anhydrate and cadmium iodide hydrate. 10. Hindered phenol is triethylene glycol bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate] and pentaerythrityl-tetrakis [3- (3,5-diphenyl). -T-butyl-4-hydroxyphenyl) propionate], N, N'-hexamethylenebis (3,5-di-tert-butyl-4-hydroxy-hydroxynamamide) and 3,9
-Bis {2- [3- (3-t-butyl-4-hydroxy-5-methylphenyl) propionyloxy] -1,1
The polymer thermosensor according to claim 8, which is at least one selected from the group consisting of -dimethylethyl {-2,4,8,10-tetraoxaspiro [5,5] undecane. 11. Naphthylamine is phenyl-α-
The polymer thermosensor according to claim 8, which is at least one selected from naphthylamine and N ', N-di-β-naphthyl-p-phenylenediamine. 12. The thermosensitive polymer according to claim 8, wherein the polyamide composition comprises a polycondensate of oxybenzoic acid ester and formaldehyde. 13. The polymer thermosensor according to claim 8, wherein the polyamide contains at least one selected from the group consisting of the following (a) to (f). (A) Polyundecaneamide (b) Polydodecaneamide (c) Polyamide containing a linear saturated hydrocarbon having 12 or more carbon atoms or a copolymer thereof (d) N-alkyl-substituted amide of polyundecaneamide or polydodecaneamide Copolymer (e) Polyundecaneamide or etheramide copolymer of polydodecaneamide (f) Dimer acid-containing polyamide 14. A thermosensitive element comprising the polymer thermosensitive element according to claim 8 disposed between a pair of electrodes. 15. The pair of electrodes, wherein the material of at least one of the electrodes is a metal selected from the group consisting of gold, platinum, palladium, silver, tin, solder, stainless steel, titanium, and indium. Thermosensitive element. 16. An electrode in which at least one of the pair of electrodes is plated or clad with a metal selected from the group consisting of gold, platinum, palladium, silver, tin, solder, titanium, nickel, and indium. The temperature-sensitive element according to claim 14, wherein