JPH059779Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a heat detection wire used to control the temperature of a heating element such as an electronic carpet, an electric blanket, or a floor heater.

[Conventional technology]

Heat detection wires are wired in an appropriate pattern on a planar heating element to detect the temperature of the heating element, and the general structure is explained with reference to Fig. 1. A primary electrode 2 is wound around the electrode, a heat-sensitive layer 3 is provided on the outer periphery of the primary electrode 2, a secondary electrode 4 is further wound on top of the heat-sensitive layer 3, and an insulating layer 5 is applied.

Copper wires (rectangular or round wires) are used for the primary and secondary electrodes, and are usually wound in parallel at a specific pitch. The heat-sensitive layer 3 has a so-called thermistor property in which the resistance decreases as the temperature rises, and detects temperature changes by detecting changes in impedance between the primary electrode and the secondary electrode. As the matrix polymer for this heat-sensitive layer, soft PVC is said to be optimal, but polyolefin resins, methacrylic acid ester resins, etc. can also be used. A quaternary ammonium salt compound generally represented by the following formula is uniformly blended into these resins as a thermistor property imparting agent.

[Problem that the invention aims to solve] The quaternary ammonium salt compound has a thermistor B constant that indicates thermistor property (the magnitude of resistance change due to temperature change)* *Here, B constant B=1nR ₀ /R/ 1/T ₀ −1/T (〓) T ₀ , T: Measured temperature (〓) R ₀ : Impedance with respect to temperature T ₀ R: Impedance with respect to temperature T is large and is the most excellent in temperature detection.
However, a heat detection wire constructed with a heat sensitive layer containing this quaternary ammonium salt compound has poor stability over time of the characteristic impedance between the primary electrode and the secondary electrode. Possible causes of changes in characteristic impedance over time include thermal decomposition, volatilization, and migration of the thermistor filler, and thermal decomposition of the matrix polymer, but even if measures are taken to prevent these effects from occurring, However, no significant improvement effect on stabilization of characteristic impedance was observed. The present invention provides a heat sensing line in which a matrix polymer containing a quaternary ammonium salt compound is provided between the primary electrode and the secondary electrode as a heat sensitive layer for temperature control. The purpose is to improve the stability over time of the characteristic impedance between

[Means for solving problems]

In the course of a series of studies aimed at stabilizing characteristic impedance, the present inventors noticed the following trends. The change in volume resistivity over time of a sheet-like heat-sensitive material containing a quaternary ammonium salt compound was evaluated under specified conditions and was found to be extremely good. The stability over time of the characteristic impedance between the former and the secondary electrode is inferior to that of the former under the same conditions.

From this, it is clear that the fourth thermistor-improving agent
It was speculated that some kind of chemical reaction occurred at the contact surface between the grade ammonium salt compound and the copper wire serving as the electrode, resulting in a change in characteristic impedance over time. Since the quaternary ammonium salt compound reacts with copper to produce copper salts such as copper halides and copper perhalates, its concentration will decrease and the impedance characteristics will change.

Therefore, the present invention has proposed that in the above-mentioned heat detection wire, tin, lead, nickel, silver, chromium, gold, iron, etc.
Copper wire 11 plated with an alloy 12 of one or more metals selected from zinc and palladium
It uses

[Effect]

According to the present invention, in order to avoid direct contact between the quaternary ammonium salt compound compounded in the heat sensitive layer of the heat detection wire and the copper wires constituting the primary and secondary electrodes, tin, lead, etc. , nickel, silver, chrome,
A metal selected from gold, iron, zinc, and palladium
The surface of the copper wire is plated with one type or an alloy of two or more types. Among the various metals mentioned above, silver and gold have a smaller ionization tendency than copper, so the above reaction is inhibited even by contact with a quaternary ammonium salt compound, and metals other than silver and gold are oxidized with lower reactivity than copper. Since it forms a film, the above-mentioned reaction is suppressed even when it comes into contact with the quaternary ammonium salt compound, and changes in the desired properties can be prevented.

〔Example〕

(1) A tin-plated copper rectangular wire is wound around the polyester core as the primary electrode, and a soft
A heat-sensing wire was manufactured by providing a heat-sensitive layer made of PVC mixed with a quaternary ammonium salt compound, winding a secondary electrode of tin-plated copper rectangular wire on top of the heat-sensitive layer, and forming a PVC insulation coating on the outside.

(2) A heat detection wire was manufactured under the same conditions as in Example 1, except that tin-lead alloy plated copper rectangular wires were used for the primary and secondary electrodes.

Comparative Example: A heat detection wire was manufactured under the same conditions as in Example 1, except that rectangular copper wires were used as the primary and secondary electrodes as before.

Figure 2 shows the temporal characteristics of the characteristic impedance between the primary and secondary electrodes of each heat detection wire sample. Note that since the aging characteristics of Examples 1 and 2 were the same, they are shown by one line.

It is clear from the figure that the thermal detection wire manufactured according to the embodiment of the present invention has much better stability of characteristic impedance over time than that of the comparative example.

[Effect of idea]

The heat detection wire of the present invention has a copper wire surface made of one or more metals selected from tin, lead, nickel, silver, chromium, gold, iron, zinc, and palladium as a conductor constituting the primary and secondary electrodes. Since the copper wire plated with two or more types of alloys is used, the characteristic impedance has excellent stability over time, and the temperature of the surface heating element can be controlled with high accuracy.

[Brief explanation of the drawing]

FIG. 1a is a perspective view showing the structure of a heat detection line according to the present invention, and FIG. 1b is an enlarged sectional view of a conductor constituting a primary electrode and a secondary electrode. FIG. 2 is a graph showing the characteristic impedance of the heat detection line over time.

Claims (1)

[Scope of utility model registration request] In a heat sensing wire in which a matrix polymer containing a quaternary ammonium salt compound is provided between the primary electrode and the secondary electrode as a heat-sensitive layer for temperature control, the conductor constituting the primary electrode and the secondary electrode As, tin, lead, nickel, silver, chromium,
A metal selected from gold, iron, zinc, and palladium
A heat detection wire characterized by using a copper wire plated with one type or an alloy of two or more types.