JPS63116312A - Heat sensitive wire - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a heat-sensitive wire for temperature detection used in planar heating devices such as electric blankets and electric carpets.

Conventional technology In general, surface heating devices such as electric blankets and electric carpets are
A cord-shaped heating wire and a heat-sensitive wire for temperature detection are arranged in a meandering manner, and the heat-sensitive wire serves to detect the temperature of the planar heating device and control the current flowing through the heating wire.

The structure of the heat-sensitive wire is as shown in FIG. 4, for example.

A heat sensitive element 6 having a negative temperature coefficient is coated around the outer periphery of the inner metal conductor 2 spirally wound around the core yarn 1 and its outer periphery, and then an outer metal conductor 4 is coated around the outer periphery of the heat sensitive element 3. After winding in a spiral, a shielding tape 7 is wrapped around it, and an insulator 6 made of polyvinyl chloride is further covered.

The heat sensitive body 3 is made of a resin such as polyvinyl chloride or polyamide with 1 to 5% by weight of an additive such as a quaternary ammonium salt, imidazole, or oxazole added to improve temperature detection sensitivity, and the impedance is By applying the electric field to the internal metal conductor 2 and the external metal conductor 4, the impedance at that time is detected, and combined with a temperature control circuit, the electric field changes with temperature. It controls the current.

However, the shielding tape 7 does not prevent the heat susceptor 6 from leaking due to the migration of additives added to the heat susceptor B into the insulator B or the migration of plasticizers in the insulator B to the heat susceptor 6. This is provided for the purpose of reducing the change in impedance of B over time, and heat-resistant plastic film is widely used.

Problems to be Solved by the Invention However, according to the above configuration, the additive added in the heat sensitive body 3 has a property of moving toward the side where the additive concentration is lower by heating gh, and therefore and bleed to the shielded Chigua side.

In particular, since the core yarn 1 and the heat sensitive body 3 are in contact with each other, a migration phenomenon is likely to occur. The migrated additive continues to bleed until the concentration at the contact interface reaches equilibrium, so the impedance changes over time.

Therefore, to reduce the change in impedance over time,
It is necessary to add more than an appropriate amount of additives, and as a result, there are disadvantages in that the heat aging resistance of the heat sensitive body B deteriorates and the molding processability deteriorates.

Means for Solving the Problems The present invention has been made to eliminate the above-mentioned drawbacks.
and an inner metal conductor wrapped around the outer circumference of the core thread.

A heat sensitive body having a negative temperature coefficient characteristic provided around the outer periphery of the stiffness, an outer metal conductor wrapped around the outer periphery of the heat sensitive body,
It consists of a shielding body wrapped around the outer periphery of the heat sensitive body, and an insulator provided around the outside of the shielding body, and the negative of the heat sensitive body is attached to at least one of the core yarn or the shielding body. It is impregnated with additives that improve temperature coefficient characteristics.

Effect With the above structure, at least one of the core yarn or the shielding body that comes into contact with the heat sensitive body can be impregnated with an additive that improves the negative temperature characteristics of the heat sensitive body. The concentration of additives on the surface is high, making it difficult for the additives added inside the heat sensitive body to improve the negative temperature characteristics to bleed out or to migrate to the core thread or the shielding body.

Changes in impedance over time can be prevented.

Example An embodiment of the main island side will be described below with reference to the drawings.

The structure of the embodiment is as shown in FIG. 1, and numeral 1 is a core yarn made of heat-resistant fiber such as polyester or polyamide. Reference numeral 2 denotes an inner metal conductor, which is made of copper or copper alloy and is spirally wound around the outer periphery of the core thread 1.

Reference numeral 3 denotes a thermosensitive material, which is made of an additive added to a resin such as polyvinyl chloride or polyamide to improve negative temperature coefficient characteristics, and is coated around the outer periphery of the core yarn 1 and the inner metal conductor 2 by extrusion processing. It is. This is a four-piece outer metal body made of copper or copper alloy, which is wound in a spiral around the outer circumference of the heat sensitive body. Reference numeral 5 denotes a shielding body made of fibers such as polyester or polyamide, which includes a heat sensitive body 6 and an outer metal conductor 4.
It is wound spirally around the outer periphery of the heat-sensitive member 3 and brought into close contact with the heat-sensitive member 3. Reference numeral 6 denotes an insulator made of polyvinyl chloride, which is coated around the outer periphery of the shielding body 5 by extrusion processing. Note that the core yarn 1 is immersed.

Next, the operation of this embodiment having the above configuration will be explained.

FIG. 2 shows nine embodiments A (in the configuration shown in FIG. 1,
The heat sensitive element 6 is made by adding 2.0% quaternary ammonium salt to soft vinyl chloride, and the core yarn 1 and the shielding body 5 are made by impregnating the surface of polyester fiber yarn with 0.1% quaternary ammonium salt solution. It is something that ) and conventional example B (in the configuration shown in FIG. 4, the heat sensitive body 6 is soft vinyl chloride with 3.8% quaternary ammonium salt added).
This figure shows the change in impedance over time when the sample was left in an aging oven at 00°C. Looking at the characteristics of the two, it can be seen that the characteristics of the conventional example B change greatly over time, whereas the characteristics of the example A become slightly smaller at the beginning, but are almost stable thereafter.

The phenomenon in which the rate of change in impedance changes to the negative side in Example A is due to the fact that the surface of the core yarn 1 or the shielding body 5 is treated with a surfactant to improve negative temperature characteristics.
This is thought to be due to the transition into the

Figure 6 shows the heat-sensitive bodies 6 of Example A and Conventional Example B formed into sheets with a thickness of 1 layer, left at 100° C., and subjected to a tensile test at each descending time to examine the elongation rate at that time. It is something. From the results, it was found that the elongation rate characteristics of Example A were the same as those of conventional example B.
It is superior in that it shows less change over time. This indicates that the smaller the surfactant content in the heat sensitive body B, the less likely it is to accelerate the deterioration of the resin. Furthermore, if the amount of surfactant in the heat-sensitive member 3 is small, the additive becomes difficult to thermally decompose during molding, and thus molding processability is improved.

The core yarn 1 and the slow-closing body 5 are made of heat-resistant fibers.

It is easy to treat the surface of the heat sensitive body with an additive that is the same as the surfactant or of the same type as the surfactant that improves the negative temperature characteristics of the heat sensitive body. In addition, the slow-closing body 5 has a structure in which heat-resistant fiber threads are spirally wound in parallel, so that even if heat or mechanical stress is applied from the outer periphery of the insulator 6, it can function as a buffer. Durability is improved.

Effects of the Invention The present invention has the following excellent effects and has great industrial utility value. Namely.

By impregnating the surface of at least one of the core thread and the door closing body that comes into contact with the heat sensitive body with a surfactant that improves the negative temperature characteristics of the heat sensitive body.

(1) Since the bleeding of the surfactant added to the heat sensitive element is reduced, the change in impedance over time is reduced, and as a result, stable temperature detection is possible for a long period of time.

(2) Since the amount of the additive that improves the negative temperature coefficient characteristic added to the heat susceptor can be reduced, the heat aging resistance and molding processability of the heat susceptor are improved, and the reliability of the durable life can be obtained.

[Brief explanation of the drawing]

Figure 1 is a structural diagram of a heat-sensitive wire showing an embodiment of the present invention, Figure 2
Figure 6 and Figure 6 are time-dependent characteristic diagrams of this embodiment and the conventional example.
The figure is a structural diagram of a conventional heat-sensitive wire. 1... Core yarn 6... Heat sensitive body 5... Slow closing body

Claims (1)

[Claims] an inner metal conductor wrapped around the outer periphery of the core yarn; a heat sensitive body having a negative temperature coefficient characteristic provided around the outer periphery of the inner metal conductor;
A heat-sensitive wire comprising an outer metal conductor wrapped around the outer periphery of the heat-sensitive body, a shielding body wrapped around the outer periphery of the outer metal conductor, and an insulator provided around the outer periphery of the shielding body, The core yarn (1
) or at least one of the shielding body (5),
A heat-sensitive wire characterized in that it is impregnated with an additive that improves the negative temperature coefficient characteristic of the heat-sensitive member (3).