JPH06323926A - Polymer temperature-sensor and thermosensitive element using it - Google Patents

Abstract

PURPOSE:To enhance the temperature dependency of an impedance and the thermal stability of the polymer temperature-sensor by a method wherein a composition in which cobalt or nickel iodide, a specific phosphorus ester-based compound and, in addition, one or more kinds out of naphtylamine and a hindered phenol-based heat-resistant stabilizer have been compounded with a polyamide is used as a temperature-sensor. CONSTITUTION:A temperature-sensor is formed mainly of a polyamide composition in which cobalt iodide or nickel iodide, a phosphorus ester-based compound at a phosphorus concentration of 3 to 20wt.% and at a molecular weight of 200 to 5000 and, in addition, a compound of one or more kinds out of naphthylamine and a hindered phenol-based heat-resistant stabilizer have been compounded with a polyamide. Then, the polymer temperature-sensing body 3 is arranged and installed between one pair of electrode wires 2, 4, and a temperature change in its physical property is detected by the electrode wires 2, 4. Thereby, the contact of the polymer temperature-sensor with the winding electrodes is made good, and the heat-resistant property of the temperature- sensor as a temperature sensor can be enhanced.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art Heretofore, this type of polymer temperature sensor is generally arranged between a pair of winding electrodes and is used as a flexible linear temperature sensor or a heat sensitive heater. A polyamide composition such as nylon 12 or modified nylon 11 (manufactured by ATO-CHIMIE, trade name "Rilsan N nylon") disclosed in JP-A-55-100693 is used as the polymer temperature sensor. It functions as a temperature sensor by detecting a temperature change such as its capacitance, resistance value or impedance. Further, in JP-A-60-48081, a polyamide composition in which a phosphite is added as a heat deterioration improving agent and in JP-A-64-30203 are an ion in which a copper deactivator and a phenolic antioxidant are added. Examples of conductive heat sensitive compositions are disclosed.

[0003]

However, in the above-described conventional polymer temperature sensitive body, for example, nylon 12 is excellent in that it has a low moisture absorption rate, but as a temperature sensor, the variation of the temperature sensitive characteristic due to humidity is caused. Because it is large, it is difficult to put it to practical use. 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, a composition containing an aldehyde polycondensate of a phenolic compound has been proposed as disclosed in Japanese Patent Publication No. 3-50401. However, these all have problems that the temperature dependence of impedance is low and the thermal stability for a long period of time is insufficient.

An object of the present invention is to solve the above problems, and to provide a polymer temperature sensor having a large temperature dependency of impedance and excellent thermal stability, and a heat sensitive element using the same. It is a thing.

[0005]

In order to solve the above-mentioned problems, the present invention provides a polyamide containing cobalt iodide or nickel iodide, a phosphorus concentration of 3 to 20% by weight, and a molecular weight of 200 to 5,
A composition prepared by blending 000 phosphite compounds and at least one of naphthylamine and a hindered phenol heat stabilizer is used as a temperature sensitive body.

Further, the above-mentioned polymer temperature sensing element is arranged between a pair of electrodes, and the temperature change of the physical property of the polymer temperature sensing element is detected by both electrodes.

[0007]

In general, the polymer temperature sensor is arranged between a pair of copper or copper alloy winding electrodes and used as a flexible linear temperature sensor or a heat sensitive heater. The heat resistance stability of these temperature sensors and heat sensitive heaters is determined by the stability of the polymer temperature sensor itself and the surface condition of the winding electrode. When the polyamide composition of the present invention is used, high temperature oxidation due to heating of the winding electrode is significantly suppressed by the presence of at least one compound of naphthylamine or hindered phenol heat resistance stabilizer in the polymer temperature sensor. To be done. Furthermore, the temperature dependence of the impedance is remarkably enhanced by the ion carrier properties of cobalt iodide and nickel iodide.
Furthermore, it forms a cobalt complex with an amide group, and enhances the electrical stability. Moreover, such as tetraphenyl dipropylene glycol diphosphite, tetraphenyl tetra (tridecyl) pentaerythritol tetraphosphite and hydrogenated phenol A / pentaerythritol phosphite polymer, diphosphite or tetraphosphite having a high molecular weight and a high phosphorus concentration or Due to the synergistic effect of the antioxidant property and the reducing rust preventive effect of the phosphite-based polymer, the heat deterioration property is significantly suppressed. This effect is low when the phosphorus concentration is low, and too high is not practical. A phosphorus concentration of 3 to 20% by weight is effective, but a phosphorus concentration of 5 to 15% by weight is the best. If the molecular weight is low, it tends to volatilize at high temperatures, resulting in poor sustainability of the effect. Further, if it exceeds 5,000, it becomes difficult to disperse, so 300 to 3,500 is desirable for practical use. By mixing naphthylamine and hindered phenol in the presence of such cobalt iodide or nickel iodide and phosphite, rust prevention and oxidation can be synergistically achieved. These combinations do not interfere with each other even if their actions overlap, but they have a synergistic effect by being added. Therefore, it is considered that the thermal stability of the polymer temperature sensitive body is improved, and the heat resistance stability of the temperature sensor or the heat sensitive heater is significantly increased. Further, by blending an aldehyde polycondensate of a phenol compound, a strong moisture absorption preventing effect can be imparted. Phenolic compounds have good compatibility with polyamides and coordinate with hydrogen bonding sites in the polyamide instead of water molecules to reduce the hygroscopicity of the polyamide and reduce fluctuations in temperature-sensitive characteristics due to humidity. Further, the action on the amide group also has the effect of increasing the temperature sensitivity.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. As the polyamide used in this example, nylon 12 having a low hygroscopic property and N-alkyl-substituted polyamide are used.
11. Polyetheramide and polyamide containing dimer acid were selected. Cobalt iodide or nickel iodide, which has high thermal stability, was used as a conductivity-imparting agent for increasing the temperature dependence of impedance of these polymers. In addition, it has a synergistic effect with cobalt iodide or nickel iodide to enhance the antioxidant property and thermal stability. As a phosphite compound, tetraphenyl dipropylene glycol diphosphite (molecular weight 566, phosphorus concentration 10.9 Wt%), tetraphenyltetra (tridecyl) pentaerythritol tetraphosphite (molecular weight 1,424, phosphorus concentration 8.7% by weight), hydrogenated phenol A / pentaerythritol phosphite polymer (molecular weight 2,500-3,100, phosphorus concentration 1)
3.8% by weight). In addition, phenyl-α-naphthylamine was added as naphthylamine to improve the heat resistance of the nylon temperature sensor. Further, in order to enhance the antioxidant property, pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] (made by CHIBA GEICY as a hindered phenol,
The product name “Irganox 1010”) was selected. The composition ratio is such that all additives are 0.5 to 100 parts by weight of nylon.
It was 1.0 part by weight. As an example of adding an aldehyde polycondensate of a phenolic compound, an oxybenzoic acid octyl ester-formaldehyde polycondensate having good compatibility with polyamide was selected and 15 parts by weight thereof was added. Samples for measurement were prepared by blending these, kneading them with an extruder, and then forming into a sheet of about 70 × 70 mm and thickness of 1 mm with a heating press, applying silver coating on both sides of the sheet and drying to form measurement electrodes. . The temperature dependence of impedance is represented by the thermistor B constant at 40 to 80 ° C. The calculated initial impedance heat stability at 100 ° C., and the temperature at which the initial impedance for samples obtained after 100 1,000 hours half-wave energization V at 80 ° C., tables in the temperature difference [Delta] T _Z between 100 ° C. did. 40-80
The thermistor B constant at ° C was calculated based on the results obtained by measuring the impedance Z _{40 at} 40 ° C and the impedance Z ₈₀ at 80 ° C.

The measurement results of the temperature sensitive body using cobalt iodide are shown in (Table 1), and the measurement results of the temperature sensitive body using nickel iodide are shown in (Table 2).

[0010]

[Table 1]

[0011]

[Table 2]

Tables 1 and 2 show the polymer temperature sensors of Examples 1 to 12 and the polymer temperature sensors of Comparative Examples 1 to 6, respectively.
The temperature sensitive characteristics were compared. As a result, all of the polymer temperature sensitive bodies of Examples 1 to 12 exhibited a B constant of around 12000 ° K, which shows that they have higher temperature detection ability than the conventional temperature sensitive body of the comparative example.

Further, in this embodiment, as the sensitizer, anhydrous cobalt iodide or cobalt iodide hexahydrate, or anhydrous nickel iodide or nickel iodide hexahydrate is used, which has a high temperature sensitivity. It contributes to the improvement. Further, as a phosphite ester, tetraphenyl dipropylene glycol diphosphite, tetraphenyl tetra (tridecyl) pentaerythritol tetraphosphite, hydrogenated phenol A penta which has a high molecular weight, excellent non-volatility, and appropriate phosphorus concentration. Erythritol phosphite polymer is used, which contributes to the improvement of heat resistance stability and rust prevention. Phenyl-α-naphthylamine is used as naphthylamine, which contributes to the improvement of heat resistance.
Furthermore, phosphoric acid contributes to the improvement of rust resistance and heat resistance, and pentaerythrityl-
Addition of tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] synergistically improves the thermal oxidation resistance. Hindered phenols include N, N'-hexamethylenebis (3,5-di-t-butyl-4-hydroxy-hydroxynamamide), 1,3,5-
Trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene and 3,5-di-t-butyl
-4-Hydroxy-benzylphosphonate-diethyl ester is preferred, and the above combinations exert a synergistic effect. In addition, the aldehyde polycondensates of phenol compounds are p-oxybenzoic acid octyl ester-aldehyde polycondensates and p-oxybenzoic acid isostearyl ester-formaldehyde polycondensates in terms of compatibility and moisture resistance. Although excellent, aldehyde polycondensates such as p-dodecylphenol, p-chlorophenol, and p-oxybenzoic acid nonyl ester may be used in addition to p-oxybenzoic acid alkyl ester. These are blended in 5 to 30 parts by weight with respect to the polyamide. If it is less than 5 parts 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.

Further, for evaluation as a heat-sensitive element, nylon 12 (100 parts by weight), cobalt iodide hexahydrate or nickel iodide hexahydrate (1 part by weight), tetraphenyltetra (tridecyl) pentaerythritol. Pellets of a nylon blend consisting of tetraphosphite (0.5 parts by weight) and pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] (0.5 parts by weight) were prepared. The pellets were extruded to form a thermosensitive element having the structure shown in FIG. 1, that is, a temperature detection line. Each component of FIG. 1 will be described.
1,500 denier polyester core yarns, 2 and 4 are 0.5% silver-filled copper wires, 3 is a nylon temperature-sensitive layer, 5 is a polyester separation layer, and 6 is a heat-resistant vinyl chloride jacket. The thermistor B constant of this temperature detection line was 12,800 (K). Further, it showed durability for 2,000 hours or more even with continuous 100 V energization at 120 ° C., which was conducted as a heat resistance life test, and it was found that there was no practical problem.

[0015]

As is apparent from the above description, according to the present invention, cobalt iodide or nickel iodide, a phosphite having an appropriate molecular weight and phosphorus concentration, and a hindered phenol or naphthylamine. When used together, the thermistor B constant increases about 3 times. Further, even in a high temperature storage test, mechanical strength and electrical properties are synergistically stabilized over a long period of time, and a highly reliable polymer temperature sensor in many practical applications can be provided. Further, a thermosensitive element having high temperature detection sensitivity and good heat resistance can be obtained by using the above-described polymer thermosensitive material.

[Brief description of drawings]

FIG. 1 is a partially cutaway side view showing a structure of a temperature detection heater wire using a polymer temperature sensor of the present invention.

[Explanation of symbols]

 1 Polyester core yarn 2, 4 Electrode wire 3 Nylon temperature sensitive layer 5 Polyester separation layer 6 Heat resistant vinyl chloride jacket

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical display location C08L 61/18 LNU 77/00 LQT H01C 7/00 X // H05B 3/56 B 7913-3K

Claims (9)

[Claims] 1. Polyamide, cobalt iodide or nickel iodide, and a phosphorus concentration of 3 to 20% by weight and a molecular weight of 200.
A polymeric thermosensitizer mainly comprising a polyamide composition containing up to 5,000 phosphite compounds and at least one compound selected from naphthylamine and hindered phenol heat stabilizers. 2. The polymeric thermosensitizer according to claim 1, wherein the cobalt iodide is at least one selected from anhydrous cobalt iodide and hydrated cobalt iodide. 3. The polymer thermosensitizer according to claim 1, wherein the nickel iodide is at least one selected from nickel iodide anhydride and nickel iodide hydrate. 4. The hindered phenol is triethylene glycol- [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate] or pentaerythrityl.
-Tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] or N, N'-hexamethylenebis (3,5-di-t-butyl-4-hydroxy-hydroxynamine) Mido) or 3,9-bis {2- [3- (3-t-butyl
4. At least one selected from -4-hydroxy-5-methylphenyl) propionyloxy] -1,1-dimethylethyl} -2,4,8,10-tetraoxaspiro [5,5] undecane. 1. The polymer temperature sensor according to 1. 5. The polymeric thermosensitizer according to claim 1, wherein the naphthylamine is at least one selected from phenyl-α-naphthylamine or N'N-di-β-naphthyl-p-phenylenediamine. 6. A phosphite compound is at least one selected from tetraphenyl dipropylene glycol diphosphite or tetraphenyl tetra (tridecyl) pentaerythritol tetraphosphite or hydrogenated phenol A / pentaerythritol phosphite polymer. The polymer thermosensitive material according to claim 1, which is a seed. 7. The polymeric temperature sensitive body according to claim 1, wherein the polyamide composition comprises an oxybenzoic acid ester / formaldehyde polycondensate. 8. The polymeric thermosensitizer according to claim 1, wherein the polyamide is at least one selected from the group consisting of the following (a) to (e). (A) Polyundecane amide (b) Polydodecanamide (c) N-alkyl-substituted amide copolymer of polyundecane amide or polydodecanamide (d) Ether amide copolymer of polyundecane amide or polydodecanamide (e) Polyamide containing dimer acid 9. The polymer temperature sensor according to claim 1, wherein the polymer temperature sensor is disposed between a pair of electrodes, and a physical property of the polymer temperature sensor between the electrodes is provided. A thermosensitive element that detects changes due to temperature with both electrodes.