JPH07142211A - Temperature-sensitive polymer material and temperature sensor - Google Patents

Abstract

PURPOSE:To provide a temperature-sensitive polymer material used for flexible temperature sensors or temperature-sensitive heaters for electric heating apparatuses having an excellent temperature-sensitive characteristic and thermal stability and a temperature-sensitive element using the material. CONSTITUTION:A temperature-sensitive polymer material is composed of a polyamide composition, which comprises 100 pts.wt. of polyamide, and 0.01 to 20 pts.wt. of zinc iodide, and has a temperature detecting property and excellent thermal conduction stability. A temperature-sensitive element using the material is constituted by interposing the temperature-sensitive polymer material 4 between paired electrode wires 1 and 3.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art Conventionally, a polymer temperature sensor is generally arranged between a pair of winding electrodes and used as a flexible linear temperature sensor or a heat sensitive heater. Examples of the polymer temperature sensitive material include nylon 12 and modified polyamide 11 (ATO-CHI) disclosed in JP-A-55-100693.
A polyamide composition such as a product manufactured by MIE Co., Ltd. under the trade name of “Rilsan N nylon”) is used, and its temperature change such as capacitance, resistance value or impedance is used to fulfill the function of a temperature sensor.

Further, Japanese Patent Publication No. 60-48081 discloses a polyamide composition to which a phosphite is added as a heat deterioration improving agent, and Japanese Patent Application Laid-Open No. 64-30203 discloses a copper deactivator and a phenolic antioxidant. Examples of added ion conductive heat sensitive compositions are disclosed.

[0004]

Nylon 12 is excellent in that it has a low moisture absorption rate, but it is difficult to put it into practical use as a temperature sensor, because its temperature-sensitive characteristics vary greatly depending on humidity. Further, in the modified polyamide 11 described in JP-A-55-100693, the temperature dependence of impedance is small, so that the temperature detection sensitivity is low and the heat stability is poor. Therefore, in order to improve the humidity resistance and the temperature sensitivity, Japanese Patent Publication No. 3-50401
As disclosed in the publication, a composition containing an aldehyde polycondensate of a phenolic compound is proposed.
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.

The present invention solves the above-mentioned conventional problems, and provides a polymer temperature sensor having a large temperature dependency of impedance and excellent thermal stability, and a temperature sensor using the same. To aim.

[0006]

In order to achieve the above-mentioned object, the polymer thermosensitizer of the present invention comprises a polyamide composition in which 0.01 to 30 parts by weight of zinc iodide is mixed with 100 parts by weight of polyamide. The thermosensitive element of the present invention is configured by disposing the polymer thermosensor between a pair of electrodes.

[0007]

In general, the polymer temperature sensor is disposed between a pair of copper or copper alloy winding electrodes and is 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,
Due to the ion carrier property of zinc iodide in the polymeric thermosensitizer, the temperature dependence of the impedance is remarkably increased, and a zinc complex is formed in the amide group to enhance the electrical stability.
It is also thermally stable.

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 remarkably 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 polyamides instead of water molecules to reduce hygroscopicity 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.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A polymer temperature sensor and a temperature sensor using the same according to an embodiment of the present invention will be described below with reference to the drawings.

In this embodiment, as the polyamide, nylon 12 and nylon 12-nylon 40, which have low hygroscopicity, are used.
Choose a copolymer, N-alkyl substituted polyamide 11, polyether amide, or dimer acid containing polyamide,
These were used alone or in combination at a fixed ratio.

Zinc iodide, which has high thermal stability, was used as a conductivity-providing agent (sensitizer) for increasing the temperature dependence of impedance of these polymers.

In the case where an aldehyde polycondensate of a phenol compound was further added, an oxybenzoic acid octyl ester-formaldehyde polycondensate having good compatibility with polyamide was selected.

The sample was blended with these, kneaded by an extruder, and then heated by a press to about 70 mm × 70 mm, thickness 1 mm.
Was formed into a sheet and the electrodes coated with silver were provided on both sides of the sheet. The temperature dependence of impedance is represented by the thermistor B constant at 40 ° C to 80 ° C. The heat resistance stability was expressed as a temperature difference (ΔT _z ) between the initial impedance and the impedance after 100 V half-wave energization at 100 ° C. for 1,000 hours. The thermistor B constant at 40 ° C. to 80 ° C. was calculated based on the results of measuring the impedance Z _{40 at} 40 ° C. and the impedance Z ₈₀ at 80 ° C.

Table 1 shows the contents and results of Examples 1 to 6 and Comparative Examples 1 and 2 showing the composition and characteristics of the above-mentioned polymeric thermosensitive materials.

[0017]

[Table 1]

As the sensitizer of this embodiment, anhydrous zinc iodide or zinc iodide dihydrate is used. Thermistor B
It contributes to the improvement of the constant.

These are blended with 0.01 to 30 parts by weight of zinc iodide based on 100 parts by weight of polyamide.
If the amount of zinc iodide is less than 0.01 parts by weight, the sensitizing effect and half-wave current stabilizing effect are low, and if the amount of zinc iodide is more than 20 parts by weight, the physical properties of the composition are significantly impaired.

As the aldehyde polycondensate of the phenolic compound, p-oxybenzoic acid octyl ester-aldehyde polycondensate and p-oxybenzoic acid isostearyl ester-formaldehyde polycondensate are compatible and moisture resistant. However, 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 aldehyde polycondensates are blended in an amount of 5 to 30 parts by weight with respect to 100 parts by weight of polyamide. If the amount is less than 5 parts by weight, the effect is low, and if the amount is more than 30 parts by weight, the properties of the composition are improved. Remarkably damages.

Nylon 12 (10
0 parts by weight) and a pellet of a polyamide composition having zinc iodide (1.0 parts by weight) were prepared, and the pellet was used to prepare a temperature sensitive element, that is, a temperature detection line as shown in FIG.

The structure of this temperature sensitive element is such that a 1,500 denier polyester core yarn 2 wound with a 0.5% silver-containing copper electrode wire 1 and a polyamide feeling wound with a 0.5% silver-containing copper electrode wire 3. It is coated with a warm layer 4, and the periphery thereof is further coated with a polyester separation layer 5 and a vinyl chloride jacket 6. That is, the temperature sensor is constructed by disposing the polymer temperature sensor between the pair of electrodes. For the thermistor B constant of this temperature sensitive element, the thermistor B constant was 3,500 (K) as compared with the prototype of Comparative Example 1 shown in Table 1 in which the polyamide temperature sensitive layer 4 was formed of only nylon 12 for comparison. On the other hand, it showed 10,300 (K), which was about three times as high, and showed durability of 2,000 hours or more with respect to continuous 100 V half-wave energization at 120 ° C. performed as a heat resistance life test.

[0024]

As is apparent from the above description, according to the polymer temperature sensor of the present invention and the temperature sensor using the same,
The addition of zinc iodide can improve the thermistor B constant and stabilize the mechanical strength and electrical properties for a long period of time even at high temperature, and can improve the reliability of many practical applications.

[Brief description of drawings]

FIG. 1 is a partially cutaway side view of a temperature-sensitive element using a polymer temperature sensor according to an embodiment of the present invention.

[Explanation of symbols]

 1,3 Electrode wire 2 Polyester core yarn 4 Polyamide temperature sensitive layer (polymer temperature sensitive body) 5 Polyester separation layer 6 Vinyl chloride jacket

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kensumi Asakoshi 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Shuji Tsujiuchi 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd.

Claims (5)

[Claims] 1. A polymer temperature sensor having a polyamide composition in which 0.01 to 30 parts by weight of zinc iodide is mixed with 100 parts by weight of polyamide. 2. The polymeric thermosensitizer according to claim 1, wherein the zinc iodide is at least one selected from anhydrous zinc iodide and hydrated zinc iodide. 3. The polymer temperature sensitive body according to claim 1, wherein the polyamide composition contains an oxybenzoic acid ester / formaldehyde polycondensate. 4. The polyamide comprises the following (a) to (f):
2. At least one selected from the group consisting of
4. The polymeric temperature sensor according to any one of 1 to 3. (A) Polyundecane amide (b) Polydodecanamide (c) Polyamide containing linear saturated hydrocarbon C ₁₂ or more and copolymer thereof (d) Polyundecane amide or N-alkyl substituted polyamide copolymer of polydodecane amide (E) Polyundecanamide or Polydodecanamide Polyetheramide Copolymer (f) Dimer Acid-Containing Polyamide 5. A temperature-sensitive element comprising a polymer temperature-sensing body having a polyamide composition in which 0.01 to 30 parts by weight of zinc iodide is mixed with 100 parts by weight of polyamide and which is arranged between a pair of electrodes.