JP2743743B2 - Polymer thermosensor - 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 such as an electric heater or a 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 nylon 11 (ATO-CHIMI) disclosed in JP-A-55-100693.
A polyamide composition such as "Rilsan N nylon" (trade name, manufactured by Company E) is used, and its temperature change such as capacitance, resistance value, or impedance is used to perform the function of a temperature sensor. Further, Japanese Patent Publication No. Sho 60-48081 discloses a polyamide composition containing a phosphite as a thermal deterioration improving agent, and Japanese Patent Application Laid-Open No. 64-30203 discloses an ion conductive composition containing a copper deactivator and a phenolic antioxidant. Examples of sensible thermosensitive compositions are disclosed.

[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 them have problems such as low temperature dependence of impedance and insufficient thermal stability over a long period of time.

[0004] It is an object of the present invention to provide a polymer thermosensor having a large impedance temperature dependence and excellent thermal stability.

[0005]

SUMMARY OF THE INVENTION The present invention relates to a polyamide having a phosphorus concentration of 3 to 20% by weight and a molecular weight of 200 to 50,000.
A composition in which a phosphite-based compound of No. 0 and at least one selected from hindered phenol and naphthylamine is blended is used as a thermosensitive body.

[0006]

In general, a polymer thermosensor 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 polyamide composition of the present invention is used, it is thermally stable due to the antioxidant property of the hindered phenol or naphthylamine in the polymer thermosensor. Further, diphosphite or tetraphosphite having a high molecular weight and a high phosphorus concentration, such as tetraphenyl dipropylene glycol diphosphite, tetraphenyltetra (tridecyl) pentaerythritol tetraphosphite and hydrogenated phenol A / pentaerythritol phosphite polymer, or The effects of the phosphite-based polymer's antioxidant properties and reduction rust-preventive action significantly reduce synergistic thermal degradation. Further, the phosphite has an effect of increasing the thermistor B constant by its ion carrier property and polarity. If the phosphorus concentration is low, this effect is low, and if it is too high, it is not practical. Although the phosphorus concentration is effective at 3 to 20% by weight, the best value is exhibited at 5 to 15% by weight. On the other hand, if the molecular weight is low, it tends to volatilize at high temperatures, and the effect is not persistent. On the other hand, if it exceeds 5,000, dispersion becomes difficult. Therefore, desirably 300 to 3,500 is practical.
The combination with the phosphite compound in the present invention is not mutually alienated even if the action overlaps,
Addition has a synergistic effect. Therefore, it is considered that the thermal stability of the polymer thermosensor is improved, and the heat resistance of the thermosensor of the temperature sensor is remarkably increased. Further, by blending an aldehyde polycondensate of a phenol compound, a strong moisture absorption preventing action can be imparted. The phenolic compound has good compatibility with the polyamide, and coordinates with the hydrogen bonding site in the polyamide instead of a water molecule to reduce the hygroscopicity.
Reduce the fluctuation of temperature-sensitive characteristics due to humidity. There is also an effect of increasing the temperature sensitivity by acting on the amide group.

[0007]

The polyamides used in the present invention include nylon 12 and N-alkyl-substituted polyamide 1 having low hygroscopicity.
1. Polyether amide and dimer acid-containing amide were selected. In order to increase the antioxidant properties and thermal stability of these polymers, triethylene glycol-bis [3- (3-tert-butyl-5-methyl-4) is used as a hindered phenol.
-Hydroxyphenyl) propionate] (molecular weight 58
6.8), pentaerythrityl-tetrakis [3- (3,
5-Di-tert-butyl-4-hydroxyphenyl) propionate] (molecular weight 1177.7), N, N'-hexamethylenebis (3,5-di-tert-butyl-4-hydroxy-hydroxynamamide) (Molecular weight 637.0), 3, 9
-Bis {2- [3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxy] -1,1
-Dimethylethyl｝ -2,4,8,10-tetraoxaspiro [5,5] undecane (molecular weight 741),
Also, phenyl-α-naphthylamine (molecular weight 404) was selected as naphthylamine. As a composition for improving the antioxidant property, the reduction rust preventive action, and the thermistor B constant, tetraphenyl dipropylene glycol diphosphite (molecular weight 566, phosphorus concentration 10.9) is used as a phosphite.
% By weight), tetraphenyltetra (tridecyl) pentaerythritol tetraphosphite (molecular weight 1,424,
Phosphorus concentration: 8.7% by weight), hydrogenated bisphenol A / pentaerythritol phosphite (molecular weight: 2,500 to 3,10)
0, phosphorus concentration 13.8% by weight). The amount of the phosphite was 1.5 parts by weight based on 100 parts by weight of nylon. 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, and the amount was 15 parts by weight. After mixing these samples and kneading them with an extruder, they were heated to about 70 x 70 m
m, a sheet having a thickness of 1 mm was formed, and silver-coated electrodes were provided on both sides of the sheet. The temperature dependence of the impedance is
Expressed as a thermistor B constant at 40 to 80 ° C. The thermal stability was represented by the temperature difference (ΔT _z ) between the initial impedance at 100 ° C. and the impedance after heating air aging at 150 ° C. for 1,000 hours. 40 ~
The thermistor B constant at 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 Tables 1 and 2.

[0009]

[Table 1]

[0010]

[Table 2]

As the antioxidant of the present invention, triethylene glycol-bis [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-
Hydroxynamamide) 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 in heat resistance. Also, as the phosphite,
Tetraphenyldipropylene glycol phosphite, tetraphenyltetra (tridecyl) pentaerythritol tetraphosphite, hydrogenated bisphenol A / pentaerythritol phosphite polymer with high molecular weight and excellent non-volatility and appropriate phosphorus concentration are used, and are stable against heat. This contributes to improvement of the characteristics and the thermistor B constant. These combinations have even more synergistic effects. In addition, aldehyde polycondensates of phenolic compounds include p-oxybenzoic acid octyl ester-aldehyde polycondensate and p-oxybenzoic acid isostearyl ester-formaldehyde polycondensate, which are excellent in compatibility and moisture resistance. However, in addition to the p-oxybenzoic acid alkyl ester, an aldehyde polycondensate such as p-dodecylphenol, p-chlorophenol, and nonyl p-oxybenzoate may be used. These are blended in an amount of 5 to 30 parts by weight with respect to the polyamide. 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.

For evaluation of the thermosensitive element, nylon 12 (10
0 parts by weight), N, N'-hexamethylenebis (3,5-
t-butyl-4-hydroxy-hydroxynamamide)
(0.5 parts by weight), pellets of a nylon compound composed of hydrogenated bisphenol A / pentaerythritol phosphite polymer (1.5 parts by weight), 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.
Is 1,500 denier polyester core yarn, 2,4 is 0.5
%, 3 is a nylon thermosensitive layer, 5 is a polyester separation layer, and 6 is a heat-resistant vinyl chloride jacket. For comparison, the thermistor B constant was about three times or more of 11,200 (K) for the sample in which the thermosensitive layer was formed only with nylon 12.
This was about 7 times the durability of 2,000 hours or more with continuous application of 100 V at 130 ° C.

[0013]

As described above, according to the present invention, the combined use of hindered phenol or naphthylamine and a phosphite having an appropriate molecular weight and phosphorus concentration can improve the thermistor B constant and increase the temperature at high temperatures. In addition, the mechanical strength and electrical characteristics over a long period of time can be made synergistically stable, and the reliability of many practical applications can be improved.

[Brief description of the drawings]

FIG. 1 is a partially broken side view of a temperature detecting heater wire using a temperature sensing element.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Polyester core yarn 2, 4 Electrode wire 3 Nylon thermosensitive layer 5 Polyester separation layer 6 Vinyl chloride jacket

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI // H05B 3/14 H05B 3/14 E (72) Inventor Shuji Yamamoto 1006 Ojidoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. In-house (56) References JP-A-4-168143 (JP, A) JP-A-61-181106 (JP, A) JP-B-1-50340 (JP, B2) JP-B-60-48081 (JP, B2) )

Claims (7)

(57) [Claims] 1. A polyamide composition comprising a polyamide and at least one selected from hindered phenol or naphthylamine and a phosphite compound having a phosphorus concentration of 3 to 20% by weight and a molecular weight of 200 to 50,000. Thermosensitive body made of a product. 2. The method of claim 1, wherein the hindered phenol is triethylene glycol-bis [3- (3-tert-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-hydroxynamamide) or 3,9-bis {2- [3- (3-t-butyl-4-hydroxy-5-methylphenyl) propionyloxy]-
The polymer thermosensor according to claim 1, which is at least one selected from 1,1-dimethylethyl {-2,4,8,10-tetraoxaspiro [5,5] undecane. 3. The polymer thermosensitive body according to claim 1, wherein the naphthylamine is at least one selected from phenyl-α-naphthylamine and N′N-di-β-naphthyl-p-phenylenediamine. 4. The phosphite compound is at least one selected from tetraphenyl dipropylene glycol diphosphite, tetraphenyl tetra (tridecyl) pentaerythritol tetraphosphite, and hydrogenated phenol A pentaerythritol phosphite polymer. The polymer thermosensor according to claim 1, which is: 5. The polymer thermosensor according to claim 1, wherein the polyamide composition comprises an oxybenzoate / formaldehyde polycondensate. 6. The polymer thermosensor according to claim 1, wherein the polyamide is at least one selected from the group consisting of the following (a) to (e). (A) Polyundecaneamide (b) Polydodecaneamide (c) Polyundecaneamide or N-alkyl substituted amide copolymer of polydodecaneamide (d) Polyundecaneamide or etheramide copolymer of polydodecaneamide (e) Polyamide containing dimer acid 7. A thermosensitive element comprising the polymer thermosensitive body according to claim 1 disposed between a pair of electrodes.