JPH03211702A - Thermosensor - Google Patents

Abstract

PURPOSE:To inexpensively offer thermosensors which have a high degree freedom in the shape and area of a thermosensitive body and a high suitability for sensing the temperature of a non-dotted zone by constituting the title device of a pair of electrodes formed on an insulated substrate and a thermosensitive body made up of a semiconductive polymer whose ingredient is a partially doped electron conjugated organic polymer. CONSTITUTION:A pair of electrodes 3 and a thermosensitive body 2 made up of a semiconductive polymer whose ingredient is a partially doped electron conjugated organic polymer are formed on an insulated substrate 1. Hereupon, electron conjugated organic polymer is polypyrrole or polyaniline that is an organic polymer made up of a conjugated system where the atomic bond of the main chain of an organic polymer consists of alternated single bonds and double bonds. This structure can provide thermosensors which show sufficient variation in resistance with temperature and have NTC characteristics.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to a temperature sensing element that utilizes the NTC characteristics of a polymer semiconductor, and particularly to a temperature sensing element that has a temperature sensing element of an arbitrary shape and is suitable for sensing the temperature of a non-point area. Concerning suitable temperature sensing elements.

(Prior Art) As a temperature sensing element, an element using a sintered body of an inorganic oxide called a thermistor has been widely used. This thermistor is effective when detecting the temperature at a certain point, but if the temperature is distributed over a wide range, multiple thermistors are required.

Therefore, in recent years, there has been an increasing demand for planar temperature sensing elements that can handle this, and with advances in polymer semiconductor synthesis technology, polymer semiconductors that can have temperature sensing elements of arbitrary shapes have been developed. Temperature sensing elements have been proposed. An example of such a proposal is JP-A-55-102110.
The publication discloses a temperature sensing element using tetracyanoquinodimethane salt (hereinafter referred to as TCNQ salt).

(Problems to be Solved by the Invention) As stated in the Detailed Description of the Invention section of JP-A No. 55-102110, TCNQ salt is originally used for crystalline or powdered organic semiconductor devices. In order to obtain a temperature sensing element with a shaped thermosensor, a polymer binder is added to TCNQ salt, then dissolved in a solvent, and an element is formed by a film forming method such as screen printing or doctor blade method. is essential. However, in this case, it is not possible to obtain a reproducible temperature sensing element unless parameters such as the particle size of the TCNQ salt and the thickness of the film are accurately controlled.

Incidentally, since the TCNQ salt is expensive, further efforts and ingenuity are required from an economical point of view in order to put it into practical use.

In addition, as the polymer binder added to the TCNQ salt, thermoplastic resins such as polyvinyl acetate, polystyrene, ethylene-vinyl acetate copolymer, vinyl chloride-vinyl acetate copolymer, etc. are used, so the temperature of the element can be detected. The range is limited to below the transition point of the polymer binder used.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned drawbacks, and to provide a temperature sensing element having a temperature sensing element of an arbitrary shape and suitable for sensing the temperature of an astigmatism portion at a low cost through a simple manufacturing process.

(Means for Solving the Problems) In order to achieve the above object, a temperature sensing element according to the present invention comprises a pair of electrodes and a temperature sensitive body made of a polymer semiconductor comprising a partially doped electronically conjugated organic polymer. and are formed on an insulating substrate.

Here, the electronically conjugated organic polymer is an organic polymer in which the atomic bonds in the main chain of the organic polymer are composed of a conjugated system in which single bonds and double bonds are alternately bonded, and the electronically conjugated organic polymer is Polymers include polypyrrole or polyaniline.

The electronically conjugated organic polymer used in the present invention can be easily obtained by, for example, an electrolytic polymerization method.

At this time, commonly known acetonitrile and water may be used as the solvent, and tetrabutylammonium verchlorate, tetraethylammonium fluoroporate, hydrochloric acid, etc. may be used as the supporting electrolyte. It is possible to obtain an electronically conjugated organic polymer film.

In addition to the electrolytic method, it is also possible to synthesize an electronically conjugated organic polymer film by a chemical polymerization method using ferric chloride or the like as an oxidizing agent.

Furthermore, this electronically conjugated organic polymer film is not doped with all the seven-mer units (in terms of stoichiometry), that is, it is in a "partially doped" state.

Here, as a method for obtaining the desired B constant of the electronically conjugated organic polymer membrane, the supporting electrolyte (
There are two methods: a method of adjusting the concentration of a dopant) and a method of applying a negative potential to the electronically conjugated organic polymer film (dedoping).

In this example, the latter method was used, which allows the desired B constant and film thickness to be easily set.

Incidentally, the larger the amount of doping, the higher the electrical conductivity of the obtained polymer.

In particular, the B constant of the element is preferably 500 or more and less than 3,000. If the B constant is less than 500, NT
Although it exhibits C characteristics, temperature detection becomes impossible due to low sensitivity.

Further, if the B constant is 3000 or more, the electrical resistance of the device increases, making it impossible to obtain the desired B constant in the dedoping step.

The insulating substrate of the present invention supports the temperature sensitive body, and any insulating material can be used.
-1] is preferably lower, and quartz glass (k = 1.38)
, inorganic glass materials such as Pyrex glass (k-1-10) and polyethylene (k-0.

22), polyvinyl chloride (k = 0.16), polytetrafluoroethylene (k = 0.30), silicone rubber (k
-0,20), etc. can be used.

In addition, when using a polymeric material as an insulating substrate, it may be formed into an arbitrary shape and then crosslinked by a generally known method.

(Function) According to the above-mentioned means of the present invention, the structure is simple because it is used as a simple synthesis method, and its film forming property is effectively utilized, and it has a thermosensor of any shape and a non-point shape. It is possible to provide a temperature sensing element suitable for detecting temperature at a low cost.

Note that polypyrrole and polyaniline do not have melting points, unlike the thermoplastic resins mentioned as examples of polymer binders added to the TCNQ salt. Therefore, it is considered to be more stable with respect to temperature than Tsuchien resin.

(Example) Hereinafter, the present invention will be explained in more detail with reference to the drawings and the like.

FIG. 1 is a sectional view showing one embodiment of a temperature sensing element according to the present invention.

<Example using polypyrrole> As shown in FIG. 1, a quartz substrate (thermal conductivity at 300K = 1.38) with length, width, and thickness of 15 mm x 15 mm x 0.5 mm was prepared as the insulating substrate 1, and the substrate Temperature sensing element 2 on top
Attach a polypyrrole membrane as a protective layer. Next, gold was vacuum deposited on both ends of the temperature sensitive body 2 and electrodes 3 were provided to form a temperature sensing element.

Here, the polypyrrole film was synthesized by the method described below.

First, we prepared reagent-grade acetonitrile distilled once more as a solvent, and used it as an anode (1000 people 25Ω/
Polypyrrole mixed with a supporting electrolyte was electrolytically polymerized in an electrolytic cell equipped with a platinum electrode as a glass electrode with ITO to form a film on the anode.

At this time, the initial concentration of pyrrole is 0, IM/l, and the supporting electrolyte is 0.075 M/l! ! / of tetrabutylammonium verchlorate was used. Also, the doping conditions are: 3. Electrode potential. Ov and 3.5V1 electrolysis time is 10 minutes.

Next, for the polypyrrole film formed on the anode in this way, the interelectrode potential was -3, OV, the electrolysis time was 1 minute, and 10
The B constant of the polypyrrole film was controlled by dedoping under conditions of 1 minute.

In this example, four types of temperature sensing elements (this example A
, B, C, D) were created.

Furthermore, Table 1 shows the doping conditions for each element.

Dedoguing conditions and B constants are shown.

When the electric resistance (temperature characteristics) of the four types of temperature sensing elements described above was measured against temperature changes, a graph as shown in FIG. 2 was obtained.

According to FIG. 2, the element of Example A (B constant 250) has a low rate of resistance change with respect to temperature change and is not suitable as a temperature sensing element. Examples B, C, and D have B constants of 500.1430 and 2300, respectively, and these have sufficient resistance changes with respect to temperature changes and are suitable as temperature sensing elements having NTC characteristics.

Also, although not included in this example, the B constant is 30
If it is more than 00, the electrical resistance of the device increases and a desired B constant cannot be obtained in the dedoping step.

It should be noted that in both Examples A and B, polypyrrole films with a thickness of 15 μm were obtained, and in both Examples C and D, polypyrrole films with a thickness of 10 μm were obtained. That is, a reproducible thermosensitive body can be obtained by controlling the minimum necessary parameters of the hexamer concentration, the supporting electrolyte concentration, and the electrolytic polymerization conditions.

<Example in which the thermal conductivity of the insulating substrate was changed> Next, the responsiveness of the element was compared for insulating substrates having different thermal conductivities.

In this Example
Quartz substrate with width and thickness of 15Xl 5XO, 5mm (3
The thermal conductivity at 00K is -1,38), and the time-resistance characteristics are measured after being left in a constant temperature bath kept at 80°C to determine the thermal time constant τ.
The results are shown in Table-2.

In Comparative Example Y, the temperature sensor was the same as Example X, and the length, width, and thickness of the insulating substrate were 15X15X.
Using the same method as Example The results are also listed in Table 2.

As can be seen, the responsiveness of the element is excellent in Example X, which uses a substrate with low thermal conductivity, and in Comparative Example Y.
The response time required is about 20 times that of Example X.
;.

Example using polyaniline> Next, a temperature sensing element was created using polyaniline instead of polypyrrole as the temperature sensing element.

The polyaniline film was synthesized by the method described below.

First, prepare water as a solvent, and use it as an anode (1000A2
Polyaniline mixed with a supporting electrolyte was electrolytically polymerized in an electrolytic cell equipped with a platinum electrode as a glass electrode with ITO (5Ω/mouth) to form a film of polyaniline on the anode.

At this time, the initial concentration of aniline is 1. OM/,/, and 1.5M/,4 hydrochloric acid was used as the supporting electrolyte. Also, the doping condition is an interelectrode potential of 2.5V.

The electrolysis time was 10 minutes.

Next, the polyaniline thus formed on the anode was dedoped under the conditions of an interelectrode potential of -2.5 V and an electrolysis time of 10 minutes to control the B constant of the polyaniline film.

In this example, two types of temperature sensing elements (this example E
, F) was created.

Furthermore, Table 3 shows the doping conditions for each element.

Dedoping conditions and B constants are shown.

When we measured the electrical resistance (temperature characteristics) of the two types of temperature sensing elements mentioned above against temperature changes, we were able to obtain a graph as shown in Figure 3.

According to FIG. 3, the element of Example E (B constant 270) has a low rate of resistance change with respect to temperature change and is not suitable as a temperature sensing element. Example F (B constant 150
0) has a sufficient resistance change due to temperature change, and N
It can be seen that it is suitable as a temperature sensing element having TC characteristics.

(Leaving space below) Table = 1 Table 2 Table 3 (Effects of the invention) As explained above, according to the present invention, film formability can be improved without using crystalline or powdered organic semiconductors such as TCNC'l salt. By using a good electronically conjugated organic polymer (polypyrrole or polyaniline) as a temperature sensing element, we can create a low-cost temperature sensing element suitable for temperature sensing in non-point areas with a high degree of freedom in the shape and area of the temperature sensing element. It is possible to provide this product, and its industrial value is extremely large.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing one embodiment of a temperature sensing element according to the present invention. FIGS. 2 and 3 are temperature characteristic diagrams of the temperature sensing element according to this embodiment. l...Insulating substrate 2...Temperature sensing element 3...Electrode

Claims (3)

[Claims] (1) A temperature sensing element composed of a pair of electrodes formed on an insulating substrate and a temperature sensitive body made of a polymer semiconductor whose component is a partially doped electronically conjugated organic polymer. (2) The temperature sensing element according to claim 1, wherein the electronically conjugated organic polymer is polypyrrole. (3) The temperature sensing element according to claim 1, wherein the electronically conjugated organic polymer is polyaniline.