KR920003017B1 - Conductive heat storage medium - Google Patents

Abstract

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Description

Thermoelectric resistance composition and self-regulating heating element using the same

1 to 3 show three kinds of electric resistance measuring instruments according to the embodiment of the present invention.

1 is a side view.

Figure 2a is a perspective view.

Figure 2b is a cross-sectional view taken along line A-A.

3a is a plan view.

Figure 3b is an enlarged cross-sectional view B-B.

4 is a graph showing the relationship between the temperature and the electrical resistance of the cyclic polyethylene glycol of Example 1-5 of the present invention.

5 is a graph showing the relationship between graphite composition, temperature, and energization time of polyethylene glycol of Example 6 of the present invention.

6 is a graph showing the relationship between energization time, temperature and current of Example 6 of the present invention.

7 is a graph showing the relationship between temperature and electrical resistance of linear polyethers of Example 7-11 of the present invention.

8 is a plan view of a planar heating element.

9 to 12 are graphs showing the relationship between the energization time and temperature, and the energization time and current (or power consumption) of the planar heating element.

* Explanation of symbols for main parts of the drawings

1: thermosensitive resistance composition 2: test tube

3: stainless electrode 4: temperature sensor

5: silicone rubber stopper 6: glass plate

7: copper foil 8: fiber layer

9 non-conductive sheet 10 copper foil tape electrode

11: end tape 12: lead wire

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a thermoelectric composition having a rapid change in electrical resistance at a constant temperature and having a positive characteristic, and a self-regulating heating element using the same.

In general, the conductivity of a material is determined by the number of charge carriers in the material and the mobility of its carriers. In the case of carbon, the carrier is the conduction band electron, so the number of carriers depends on the number of electrons in the conduction band, ie Aexp (-W / KT) in Boltzmann's law. Where A is an integer, W is a bandgap between the consumer electronics and the conduction band, K is the Boltzmann constant, and T is the absolute temperature. Mobility, on the other hand, is generally expressed as Aexp (-W / KT). Where A is an integer and W is the activation energy of hopping. Therefore, the temperature change of the conductivity δ can be generally expressed as δ = δoexp (−ΔE / KT). By the way, below a certain temperature, but according to the above formula, there is a material exhibiting a much higher resistance value than calculated by the above formula. This property is called "static property."

Conventionally, as an inorganic substance, a substance having a small amount of the histo-element added to barium titanate is used. On the other hand, a three-component system of carbon-paraffin-polyethylene is known as having a sufficiently large positive property in organic materials, but this composition has a poor compatibility of carbon and has a problem in change of mixing method and properties over time. When the temperature of the thermosensitive resistive composition with positive characteristics is raised at low temperature, the resistance increases rapidly when a certain temperature is reached. On the contrary, when the temperature of the composition is lowered at a high temperature above a certain temperature, the resistance decreases at the constant temperature. Here, when electricity is generated and energized by the composition of the present invention, a lot of current flows in the initial stage of energization, but when the temperature reaches a certain temperature, the current flows minutely because the resistance increases rapidly. When the temperature of the composition decreases, the resistance decreases, so that the current increases and recovers to a constant temperature again. By using the above properties can be used as a temperature sensor temperature fuse, self-temperature control heating element.

Melting point is organic compound at room temperature ± 50 ℃ and has high thermal stability, but many of them are poor conductors with good physical properties with low toxicity. Examples thereof include paraffins, polyalkylene glycols, higher alkyl ethers, higher alkyl esters, higher fatty acids and higher alcohols.

These organic compounds are known as heat storage media because they dissolve when the melting point becomes higher by external heating and accumulate in the material due to latent heat of melting. By using these heat storage media, heat generation can also be accumulated in the electric heat heater in the power generator by the irregular natural energy such as wind, hydraulic power, tidal power and solar heat. The heat storage medium is a poor conductor of electricity by itself and cannot be directly energized and heated, which requires a heating using a heat heater or a thermostat for temperature control, a thermistor protector, and the like, and the cost of equipment is added.

As the thermoelectric resistance composition having the positive and positive characteristics is a self-regulating heating element as described above, it acts as a temperature fuse on the temperature sensor itself and is safe without installing another temperature sensor or temperature fuse in the heating element. It can be used for economical regenerative heating system.

As a result, the thermosensitive resistance composition of the present invention has the property of not rising above a certain temperature due to the inherent properties of the resistor.

Therefore, the heating element using this has no malfunction and the stability is very high. In terms of energy, it does not exceed a certain temperature, so there is no energy waste and it is economically superior.

The present inventors encapsulate these compositions together with electrodes in an insulator to produce a heating element, in particular a planar heating element, and a heating mat for a livestock such as floor heating equipment, heating carpet, meat, meat, seedlings, etc. It is to develop a suitable one for the description of.

The present inventors have found that polyethylene glycol is very compatible with carbon powder in organic compounds and has been studied for the reason. As a result, organic compounds having different alkylene oxide units in the molecule of organic compounds have different unit structures. Compared with the carbon powder which is especially excellent compared with this, it confirmed that it showed stable static characteristics, and completed this invention.

The composition according to the present invention is very easily dispersed with respect to an organic compound containing a large number of alkylene oxides in the unit structure of the carbon having a large static characteristics in the present invention can obtain a very large static properties stably It is characterized by being. Organic compounds containing a plurality of alkylene oxides in a unit structure in a molecule show excellent static characteristics regardless of linear or cyclic form. The specific compounds are listed as follows.

Examples of linear compounds include polyoxyalkylenes such as polyethylene glycol and high molecular weight polyethylene oxides, block copolymers of polyoxyethylene and polyoxypropylene (so-called flonic and tetronic), and polyoxyethylene alkyls. Amine, polyoxyethylene sorbitan fatty acid ester, etc. are mentioned.

As the cyclic compound, trioxane and various crown ethers such as dibenzo-14-crown-4, 15-crown-5, benzo-15-crown-5, 18-crown-6, dibenzo-18-crown-6 , Dicyclohexyl-18-crown-6, dibezo-21, -crown-7, dibenzo-24-crown-8, dicyclohexyl-24-crown-8, tetrabenzo-24-crown-8, di And many others, such as benzo-60-ground-20. The static characteristics of the thermosensitive resistance composition using the same will be specifically described later.

Among the above molecules, carbon mixed with an organic compound containing a plurality of alkylene oxides in a unit structure is a carbon fine piece in the form of powder, fibrous or single crystal whisker such as graphite, activated carbon, amorphous carbon, and the like, or linear or cyclic poly It means what can be mixed in ether.

The mixture of both is very stable and uniformly mixed in any composition ratio, and the biggest characteristic is that it does not phase separate. In addition, there is a region exhibiting positive characteristics depending on the mixing ratio of the carbon fine pieces, which is in the range of 10 to 80 for the normal organic matter 10. If it is less than 10, it has high resistance and it is not energized. If it is more than 80, it is reversely energized and does not exhibit static characteristics due to temperature change. However, the range represented by the static characteristics varies greatly depending on the type of organic compound or the type of carbon microparticles, and therefore is not limited to the above range. In organic compounds, alkylene oxides, which are present in several molecules of the molecule, play an important role in the dispersion of carbon microparticles, which is considered to be a very stable and large static factor.

Alkylene oxides may be linear or cyclic, and even if the bonds of the alkylene oxides are interrupted by any trioxane of three alkylene oxides or by the six-membered ring of cyclohexane or the cyclohexane in the crown ether, The presence of several alkylene oxide groups in the molecule is demonstrated in the examples described below which exhibit positive properties.

Polyethylene glycol has the most desirable properties in the development process so far, and proves that even if the ring of polyoxypropylene is bonded to it and the terminal group is substituted with alkoxy group such as methoxy group or alkyl ester or alkylamine in hydroxyl group, It became.

As mentioned above, the reason why the mixture of the organic compound and the carbon microparticles containing a plurality of alkylene oxides in the unit structure has a large static property is not fully understood, but these compounds uniformly disperse the carbon powder very well. It seems to have property to let.

To explain the reason, first, it is well known that protons and gold ions coordinate with a secondary electron of an ether bond. On the other hand, the carbon microparticles have a graphite structure, it is well known that π electrons can move in the conjugate system, and this gives conductivity. If π electrons of carbon are localized in the crystal now, other places in the crystal become local (fra) (+), and this part is coordinated with the valence band of oxygen of alkylene oxide. Considering this, the good dispersibility of the carbon fine particles can be explained.

The conductive mechanism of the mixed system of organic compounds and carbon fine particles can be described as an omic conductive mechanism in the region where the carbon particles are in full contact with each other, but in the region with very small gaps between the particles, it is described as a conductive mechanism due to the tunnel effect. can do.

Although described in the following examples, the positive characteristic shows a sharp increase in the electrical resistance value when energized at a temperature below the melting point of the organic compound medium. These data are shown in the first table. Moreover, the relationship of the temperature-electrical resistance value of each composition is shown to FIG. 4 and FIG.

TABLE 1

The above thermosensitive resistive composition is impregnated or impregnated with a nonconductive sheet such as a thin woven fabric, a nonwoven fabric, or a sponge sheet, so as to be a thermoelectric resistive composition sheet and sealed with a nonconductive covering sheet of two front and back sheets. At the same time, when the conductors are embedded at regular intervals to form a thin sheet, the planar heating element having good properties is obtained. Of course, even if it is not thin, it is effective as a heating element, but if it is flat, it requires less material and is suitable for floor heating and wall heating as a heating element panel. And since the heating element itself has a positive characteristic, it can be used as a thermal starter or a thermal protector, so the structure is simple, there is no trouble, and the manufacturing cost is very low.

Hereinafter, the effect of the thermosensitive resistance composition of the present invention and the characteristics of the heating element using the same will be described in detail by examples.

Example 1

10 g of a thermally sensitive electrical resistance composition (1) composed of a mixture of graphite carbon (25% by weight of Yoneyama Pharmaceutical Co., Ltd.) and 75% by weight of trioxane (manufactured by Nakarai Chemical Co., Ltd., reagent grade 1) is shown in FIG. Into a test tube (2) having an outer diameter of 10 mm, it is dissolved by heating and rapidly stirred. The inlet of the test tube is sealed with a silicone rubber stopper (5) having a stainless electrode (3) and a temperature sensor (4) (covered with a Teflon membrane). The temperature and the resistance value were measured while gradually raising the temperature (about 2 ° C / min) in the vicinity of 12 degrees in the island, and the measurement was made with an industrial digital malt D611 and an alternative digital malt meter TR6841.

The measurement results are shown by the curve ① in FIG. As shown in FIG. 4, when the temperature of the thermoelectric resistance composition 1 is 40 ° C. or higher, the change in resistance starts to increase significantly. The inflection point of the resistance value is about 47 ° C., which is lower than the melting point of trioxane 64 ° C.

Example 2

A mixture of 28% by weight of graphite carbon and 72% by weight of 18-crown-6 (manufactured by West Germany Melk Co., Ltd.) used in Example 1 was melt-stirred as in Example 1, followed by temperature sensor 4 and stainless steel as in FIG. The temperature-resistance curve was obtained by attaching the electrode 3 and the silicone rubber stopper 5, and this was indicated by the curve ② in FIG. At 39 ° C., the resistance increased rapidly and clear static characteristics were obtained.

Example 3

28 wt% graphite carbon and 72 wt% benzo-15-crown-5- (manufactured by Nakarai Chemical Co., Ltd.) were melted and stirred as in Example 1, followed by the temperature sensor 4 and the stainless electrode 3 ), The silicone rubber stopper 5 was attached and the resistance value at each temperature was measured by the curve ③ in FIG. At this time, when the temperature was 60 ° C. or higher, the resistance value rapidly increased, and the positive static characteristics were shown.

Example 4

28% by weight of graphite carbon and 72% by weight of dicyclohexyl-18-crown-6 (manufactured by Nakarai Chemical Co., Ltd.) were melt mixed, and the copper foil on the glass plate 6 as shown in Figs. Iv) (7) and the copper foil (7) was attached again on it, the temperature sensor (4) was installed and the resistance value of each temperature was measured and shown in graph (4) of FIG. When the temperature was above 24 ° C, the resistance increased rapidly and high static characteristics appeared.

Example 5

28% by weight of graphite carbon and 72% by weight of dibenzo-24-crown-8 (manufactured by Nakarai Chemical Co., Ltd.) were heated and melted in a test tube as in Example 1 to measure the resistance of each temperature. ⑤ is indicated. When the temperature was 102-103 ° C or higher, resistance increased rapidly and high static characteristics were obtained even at high temperatures.

Example 6

Polyethylene glycol (manufactured by Daiichi Kogyo Pharmaceutical Co., Ltd., # 6000) was prepared by mixing 20, 40, 60, and 80% by weight of graphite carbon in a petri dish with a diameter of 12 cm and a 2.5 cm copper plate on each end. Thus, two sheets having a surface area of 10 cm 2 and 9 cm were separated and immersed in an electrode.

The mixture was cooled and solidified to room temperature, and then connected to a 100V AC power source to start the energization. The energization time, temperature change, current change, and resistance values of the initial and final energization periods were specified. The relationship between time and temperature for the initial 5 minutes of energization is shown in FIG. 5, and the relationship between temperature and amount of current is shown in FIG.

As shown in FIG. 5, 20 wt% of carbon showed no increase in temperature after energization. At 80% by weight of carbon, the temperature rises rapidly after energization. At the carbon concentration of 30-60% by weight, the temperature is increased after energizing and then maintained at a constant temperature. It is clear from FIG. 6 that this is due to the static characteristics of the thermosensitive resistance composition 1.

As the temperature rises, the resistance increases rapidly above a certain temperature, so the current decreases. If the temperature is constant, the current will be as small as in FIG. FIG. 6 shows a carbon concentration of 30% by weight in FIG.

Example 7

Polyethylene glycol (# 6000 manufactured by Daiichi Kogyo Pharmaceutical Co., Ltd.) Polyethylene glycol (copper # 2000) and graphite carbon 5: 5: 4 by weight of a mixture of hot melt and stirred, and then the fibrous layer (8) as shown in Figure 3a, b Copper foil tape electrodes 10 were attached to both sides by flowing between two non-conductive sheets 9 (300 x 80 x 0.16 mm) made of a polyester sheet attached to the inside. The whole thickness is 0.25mm. The temperature sensor 4 was attached to this surface, and the resistance value of each temperature was measured, and the result of the curve ⑦ of FIG. 7 was obtained. At 40 ° C., the bending point of the curve was visible and the static characteristics were clearly recognized.

Example 8

28% by weight of graphite carbon was mixed and heated and melted on a pronick (A68 manufactured by Asahi Kogyo Co., Ltd., F68, an average molecular weight of 8000) to which both ends of the linear molecule of polyoxypropylene were bonded. The resistance value of each temperature was measured as the sheet form shown in FIG. 3, and the result of the curve (8) of FIG. 7 was obtained. When the temperature was over 46 ℃, the resistance increased rapidly and showed a clear positive characteristic.

Example 9

The same measurement as in Example 8 was carried out in the same manner as in Example 8, but 28% by weight of graphite carbon was mixed with Pronick F88 (average molecular weight 11800), which had a slightly higher average molecular weight, and the result was indicated by the curve 9 in FIG. . As in Example 8, high static characteristics were confirmed.

Example 10

28 weight% graphite carbon was mixed with the ethyl ether terminal group of polyethyleneglycol # 5000 (made by Daiichi Kogyo Co., Ltd.), and it was made into the sheet form of FIG. Measure the resistance of. The result is shown in the curve VII of FIG. After 45 degreeC, resistance increases rapidly and high static characteristic appears.

Example 11

Polyethylene glycol # 6000 and polyethylene glycol # 2000 were mixed with 40% by weight of carbon fiber fine pieces (M-201S manufactured by Kureha Chemical Co., Ltd., diameter 15μ, length 130μ) in a weight ratio of 1: 1. As a result, the resistance value at each temperature was measured in the form of a sheet shown in FIG. 3 to obtain the result of curve VII in FIG. The rapid increase in resistance near 44 ℃ showed significant static characteristics.

Example 12

FIG. 3A is a plan view of a basic example of the planar heating element, and FIG. 3B is an enlarged view of B-B section in FIG. 3A. In this example, when the thermosensitive resistor composition 1 having the characteristics of FIG. 6 in Example 6 is sealed between two rectangular non-conductive coating sheets 9 and 9 with an insulator, The thermosensitive resistive composition 1 is impregnated, and copper foil tape electrodes 10 and 10 at both ends of the sheet in the longitudinal direction are used as the conducting wire. The non-conductive coated sheets 9 and 9 are laminated films of a polyester film and an ethylene-vinyl acetate copolymer film and heat-sealed around. The planar heating element is 100mm long and 330mm wide and its thickness is thin. Here, the characteristics of what enclosed the various thermoelectric resistance compositions 1 are shown in Example 14 or less.

Example 13

An example shown in FIG. 8 is a large planar heating element, which is made of a non-conductive sheet (9) (9) made of two sheets of 1 mm polycarbonate sheet of 500 mm long, 850 mm wide, and 4 mm thick planar heating elements. The inner surface of the planar heating element is thin and long in a lateral direction, divided into 5 pieces of butyl tape having a width of 5 mm and a thickness of 2 mm. The thin space of about 75 mm in width and about 830 mm in length is divided into 5 tapes on both ends of the butyl tape. Conductor wires 12 and 12 having a capacity of 10 A were disposed and 120 g of the thermoelectric conditioning composition 1 was filled in the thin space as it is. The composition of the thermosensitive resistance composition 1 is a mixture of 295 g of graphite powder with respect to 600 g of polyethylene glycol (# 6000).

The relation between the time when the planar heating element is applied through a 100V AC power supply and the surface temperature of the position A-E in Fig. 8 is shown in the second table.

TABLE 2

As is clear from Table 2, 7A of current flows immediately after energization, but after 1 minute, it becomes 2A, and at 5-10 minutes, it becomes approximately 0.6A of equilibrium value. The temperature also reaches 34 ° C from 21 ° C and does not rise above 37 ° C. It is a heating element that acts as a thermostat. When the temperature decreases, the resistance decreases, so that the current increases and recovers to a constant temperature. In this example, the surface temperature was measured on the coating by placing a thick paper on the surface of the planar heating element.

Hereinafter, the embodiment using another thermoelectric resistance composition having the structure of FIGS. 3A and 3B as the planar heating element will be described in detail.

Example 14

5: 5: 4 weight ratio composition of polyethylene glycol (hereinafter referred to as PEG, Daiichi Kogyo Pharmaceutical Co., Ltd., # 2000) and PEG # 6000 (produced by the same company) and graphite carbon (hereinafter referred to as GC, Oneyama Pharmaceutical Co., Ltd.) After heating, melting and mixing, the mixture was mixed between two sheets of polyester sheets (110μ thick) with fibers as shown in FIG. 3a, and the whole was formed on a sheet having a thickness of 250μ (L 500mm, W 80mm). As described above, the zig-zag copper tape is bonded to the inside of one polyester sheet in advance.

In Fig. 9, the planar heating element was supplied with AC 100V, and the temperature and power consumption of the time after application were measured. After energizing, the temperature gradually approaches the rising temperature saturation. On the other hand, power consumption also decreases rapidly with time, reaching a certain level.

Example 15

Polyoxypropylene glycol ethylene oxide (hereinafter referred to as Pronick) (average molecular weight 8000, manufactured by Asahi Teklon Co., Ltd., Pronick F 68) and GC 10: 4 weight ratio composition, Pronick F88 (average molecular weight 11800) and GC 10 : 4 weight ratio compositions were melted, respectively, to form a planar heating element as in Example 12, and the AC100V was measured for temperature and current after energization. The results are shown in FIG. In Pnikk F68 and Pnikk F88 having a structure in which PEG is bonded to both ends of the ring of polypropylene glycol, the temperature increases after the energization and is maintained at a constant temperature, whereby the current decreases correspondingly and becomes constant. Therefore, in this case, a planar heating element is possible.

Example 16

4 parts by weight of GC was added to 10 parts by weight of the methoxylated PEG # 5000, and then melted and stirred to obtain a planar heating element as in Example 12. The temperature and resistance of each time after AC100V energization were measured. The results are shown in FIG. In this case, too, the temperature rises after being energized, and is maintained at a constant temperature.

Example 17

3: 3: 4 weight non-composition of PEG # 2000, PEG # 6000, the carbon fiber microparticles (manufactured by Kureha Chemical Co., Ltd., M-201S) were melted and mixed to obtain a planar heating element as in Example 12. After AC 100V energization, the temperature and resistance of each hour were measured. The results are shown in FIG. In this case, as in Example 14-16, after the energization, the temperature was increased to be maintained at a constant temperature, and the current value was also maintained at a constant equilibrium, and thus it was proved that it can be used for various purposes as a safe and stable heating element.

Claims (6)

A thermosensitive electrical resistance composition having organic properties containing several alkylene oxides in a unit, carbon fine particles in the form of powders, fibers, whiskers, etc., and whose electrical resistance changes rapidly with temperature changes. The thermosensitive resistance composition according to claim 1, wherein the organic compound containing a plurality of alkylene oxides in a unit unit structure is a linear polyalkylene oxide and derivatives thereof. The thermally conductive resistance composition according to claim 1, wherein the organic compound containing a plurality of alkylene oxides in a unit unit structure is a cyclic ester compound. The thermoelectric resistance composition according to claim 1, wherein the mixture has a mixture of polyethylene glycol and graphite powder, and the mixing ratio is graphite powder 10-80 with respect to polyethylene glycol 100. It is composed of organic compounds containing several alkylene oxides in unit molecules and carbon microparticles in the form of powder, fiber, whiskey, etc. Magnetic temperature control heating element characterized in that the sealing with an insulator together. The self-regulating heating element according to claim 5, which is a planar heating element using a plastic sheet as the insulator.

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