JPH1092552A - Planar heating unit for residence excellent in safety - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat insulating heating system which is excellent in safety, hardly short-circuits even in the case of long term operation and does not generate abnormal heating or smoke. SOLUTION: A thermocouple to be operated for opening and closing at a temperature higher than the ordinary highest ultimate temperature, which is generated when voltage is applied to a pair of electrode bands, by 10-30 deg.C and a temperature fuse to be operated at a temperature higher than the operating temperature of the thermocouple by 10-30 deg.C are combined with a planar heating unit element, which does not have a self-control function and which has a conductive heating part formed by impregnating a conductive fiber chop with resin and a pair of electrode bands as essential element, so as to provide a heat insulating heating system for residence having multiple safety mechanism.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a safety system using a so-called planar heating element of a type which is uniformly heated over the entire surface by energization, and has a small change in electric resistance value due to temperature. Therefore, use a planar heating element that does not easily cause a short circuit in the conductive heating section even when used for a long time,
Furthermore, the present invention relates to a safety system for a sheet heating element having multiple safety valves mounted thereon in which a thermocouple and a thermal fuse are combined.

[0002] This system is particularly suitable for buildings used continuously for a long period of time, and is used for inner walls, floors, roofs, desks, chairs,
It can be used for furniture such as beds, washrooms, floors around water in bathrooms, and for use in preventing mirror fogging due to steam.

[0003]

2. Description of the Related Art Conventionally, when a planar heating element is used in a part of a building, paints, inks, etc., in which conductive particles such as carbon black are added as an electric heating element on a substrate such as a film or a sheet. Are coated or printed, and those dispersed uniformly in a thermoplastic resin or the like. These various materials have been used in various ways. Specifically, construction of a sheet heating element using conductive particles such as carbon black that can be uniformly heated over the entire area has been performed.

[0004]

However, this heating element has a problem. This planar heating element has a high electric resistance value per unit area (area resistance value), and it is necessary to apply a high voltage or reduce the distance between the electrodes in order to obtain a large heating value. However, when the voltage is high, the danger of electric discharge increases, and when the distance between the electrodes is reduced, the electrodes must be finely and precisely formed by sputtering, printing, etc., and even a part of the electrodes is damaged and cut. If it does, electricity will stop. Therefore, although a small heating element is good, it is not suitable for a sheet heating element having a large area.

[0005] When conductive particles such as carbon black are used, they have a self-temperature control function called PTC, in which the electric resistance increases due to heat generation and the current flowing automatically decreases. The point was a feature.

However, this PTC function is derived from the fact that the thermal expansion coefficient of carbon black as conductive particles is much smaller than that of the resin for fixing, and the resin between the conductive particles expands by heating to separate the conductive particles. It happens with things.

[0007] Therefore, when the self-regulating function is expressed,
There was always contact and detachment between the conductive particles, and thus it was cheap to cause contact destruction. At that time, a partial discharge caused partial carbonization of the resin and tended to cause a short-circuit route.

[0008] For this reason, it has been reported that a long-term use in a building or the like causes an accident due to a short circuit, and there has been a demand for the development of a system free from such problems.

More specifically, as a safety mechanism of a planar heating element used for a building, which generates heat uniformly over the entire surface, a mechanism combining a PTC property, that is, a self-control function function, and a temperature controller has been studied. Since it is not possible to provide a temperature controller in anticipation of a short-circuit portion that can occur during long-term heat generation, in the event of a short-circuit phenomenon, the heat-generating portion and the temperature-sensing portion often do not match, The controller did not work effectively.

[0010] In addition, the temperature controller is expensive, so it is difficult to attach a temperature sensor and a controller individually to all the sheet heating elements to be used. In many cases. Therefore, more and more cases in which abnormal heating of individual heating elements is overlooked.

[0011]

Under the circumstances described above, there has been a demand for other inexpensive and more secure systems. For this reason, the present inventors have developed a planar heating element that does not easily generate abnormal heat due to a short circuit when used repeatedly for a long period of time, has no PTC function, and uniformly generates heat over the entire heating section by energization. Inexpensive system that is economical and does not complicate or enlarge even if it is attached to all the sheet heating elements to be used with an inexpensive combination of thermocouples and thermal fuses. Have been found, and the present invention has been accomplished.

That is, the present invention relates to a planar heating element (A) having a conductive heating portion and an electrode band pair in which a resin is impregnated in a conductive fiber chop and having no PTC function. Insulation that combines a thermocouple (B) that opens and closes at +10 to 30 ° C. above the highest steady temperature reached when voltage is applied, and a temperature fuse (C) that operates at +10 to 30 ° C. higher than that Provide a heating system.

[0013] A multiple safety mechanism for controlling a current for controlling a heat generation temperature by using a sheet heating element containing a conductive substance, which cannot control a heat generation temperature by itself, which cannot exhibit a PTC function, cannot be controlled by itself. Combining can provide a more secure warming and heating system for long-term repeated use than the former using a planar heating element. This will be described in detail below.

In order for the safety mechanism according to the present invention to function, the sheet heating element must be free from local abnormal heat generation during long-term use of heat, that is, a sheet heating element that does not cause a short circuit phenomenon. If this is the case, the multiple safety mechanism can function with the combination of the thermocouple and the thermal fuse of the present invention, resulting in a system that is less expensive and more secure than in the past.

The planar heating element that uniformly generates heat over the entire heat generating portion when energized may have, for example, a conductive heat generating portion in which a conductive material is dispersed or impregnated in a resin and an electrode band pair. However, by selecting the specific configuration, either one having a PTC function or one having no PTC function as used in the present invention can be obtained.

The "sheet heating element having no PTC function" as used in the present invention can be obtained, for example, by using a conductive fiber chop as a conductive substance and selecting a resin impregnated resin. .

The planar heating element unit (A) can be obtained, for example, as follows. The conductive heat-generating portion of the heat-generating body is generally made of a conductive sheet. The sheet can be used irrespective of its form, as long as it can generate heat when energized.For example, paper, sheet, mat, nonwoven fabric, woven fabric, etc. made of various materials including conductive fibers Is suitable. Here, as the conductive fibers contained in the conductive sheet, short fibers having an aspect ratio of 50 or more are preferable. The fiber diameter is usually 5 to 20 μm.

Specifically, a so-called non-woven fabric, mat, or the like, in which a so-called paper made by a paper-making method, a contact portion of random fibers is bound with a binder, or fibers are bound together by a needle punch without using a binder,
Sheets and woven fabrics woven from yarns containing conductive fibers, such as those containing conductive fibers in a proportion of 2 to 100% by weight, can be used.

The present inventors have found that the most suitable conductive fibers contained in the sheet are carbon fiber chops (short fibers) or those containing the same.

That is, metal fibers can be used as conductive fibers other than carbon fibers. However, in the case of metal fibers, the electric resistance value is small, and when the temperature required for use in a building or the like is usually obtained. Although it depends on the fiber diameter, uniform dispersion is difficult due to the small amount used. In addition, the metal may change its electric resistance value during use due to factors such as rust and oxidation. For example, carbon fibers that do not change over time are more suitable.

Further, it has been found that a more suitable planar heating element can be obtained by using a carbon fiber chop having a fiber length of 1 mm to 200 mm as the conductive heating part as the conductive fiber chop.

In the case of carbon fiber, if the fiber length is less than 1 mm, the PTC function as described above may tend to be exhibited, which is not preferable. If the fiber length exceeds 200 mm, the electric resistance value becomes too large. It is not preferable because it becomes smaller and may cause a problem of a small use amount and uniform dispersion similarly to the metal fiber.

Further, as described later, in the case of a curved carbon fiber, the entanglement of the fiber may occur particularly when the resin is dispersed, and therefore, the fiber length is preferably 200 mm or less.

As the curved fibers in the present invention, those having a specific volume of 9 cm ³ / g or more in terms of an aspect ratio of 500 are preferable. The specific volume is the reciprocal of the bulk density measured under a pressure of 150 g / cm ² after a fiber sample is placed in a 500 ml beaker so as to fill the volume of the beaker.

When the straight fibers and the curved fibers are compared, the curved fibers are superior in terms of the stability of the carbon fiber content and the electric resistance value. In other words, when the fiber shape is straight, the electric resistance value changes linearly with the change in the content, whereas in the case of a curved shape, the tendency is small, so even if the uniformity of the content is lost, The curved shape is preferable because the deflection is relatively small. If the same electrical resistance absolute value is obtained, the curved fiber can achieve the same with a smaller fiber usage amount than the straight fiber.

As the curved carbon fiber, generally, PA
Carbon fibers known as pitch-based, rather than N-based carbon fibers, are more suitable for their production. Among them, a production method called a blowing method is particularly suitable, and carbon fibers produced by this method are most suitable. However, similar effects can be expected with straight carbon fibers produced by other methods if they are later processed into a curved shape by heat treatment or the like.

In addition, a curved carbon fiber chop is indispensable, and a straight carbon fiber may be used together if necessary as long as the PTC function is not exhibited. Further, as long as the desired PTC characteristics do not appear, it is of course possible to combine not only the curved carbon fiber chops but also other fibers (non-conductive fibers) other than the conductive fibers.

As the conductive fiber used in the present invention, a sheet or paper-like material is more suitable. In practice, it is possible to extrude these fibers into a resin from a thermoplastic resin compound to form a sheet by extrusion, but the fibers are cut off during the uniform kneading operation, resulting in a planar heating element. In this case, the stability of the resistance value deteriorates, which is not preferable in output setting.

In the present invention, the electric resistance value can be freely set by changing the content of the conductive fiber. For example, the electric resistance value can be increased by increasing the content per unit area. It is possible to reduce the power consumption, increase the power consumption, and increase the maximum temperature. In addition, non-conductive fibers or other materials can be mixed according to the required performance required.

Examples of the non-conductive fibers include various organic fibers, inorganic fibers such as glass fibers and ceramic fibers,
Most fiber-shaped materials such as pulp can be used. In order to stabilize the shape, it is preferable to use a non-conductive fiber in combination with the conductive fiber. In such a case, the content of the conductive fiber chop in the obtained element exceeds 20% by weight. It is particularly preferred that

In the present invention, a suitable conductive sheet can be obtained by impregnating the conductive fiber chop with a resin. In this case, the resin sheet is impregnated with a liquid resin which is soluble in a solvent and dried. Alternatively, alternatively, the solid non-conductive fiber may be directly heated to a temperature higher than its melting point, impregnated as a liquid, and allowed to cool.

Further, when thermoplastic organic fibers are used as the non-conductive fibers, when the melting temperature of the fibers is lower than the temperature at the time of molding as the sheet heating element, pressurization during the molding operation, When heated, it melts and loses its fiber shape, but the original purpose of this material is to hold the conductive fibers until it is molded and fixed as a sheet heating element. It is not necessary to keep that shape after it has become.

When this thermoplastic fiber is used in a sufficient weight, the impregnating resin described later is unnecessary, but when it does not have adhesiveness when heated, it is necessary to secure insulation. In many cases, adhesion to the surface film to be used is difficult. In such a case, a pressure-sensitive adhesive such as a pressure-sensitive adhesive may be used.

Further, when the fibers are melted, the function as an obstacle that has hindered the contact between the conductive fibers is lost, so that the electric resistance value is reduced. Of course, in this case, it is necessary to consider the composition design of the material of the conductive heat generating portion, such as fibers and resin, in advance of the change.

Further, depending on the required electric resistance value and other functions, a material other than a fibrous form can be added to the conductive heat generating portion as a component. When changing the conductivity and other properties as a planar heating element, and if necessary when processing into paper, sheet, mat, nonwoven fabric, woven fabric, etc.,
These materials can be added freely.

In order to further increase the conductivity of the sheet heating element,
For example, use of fine powder of metal powder or graphite powder together, add various pigments to add color to products, and various sizing for paper making and sheeting when stabilizing the shape of the conductive heating part Materials can be added.

For example, when making conductive paper by making conductive fiber and pulp into paper, various resins can be used to fix the fiber. In consideration of the electrical resistance value of the heating element obtained when using paper, the resin type and the composition ratio may be designed,
Materials other than the conductive material may be collectively evaluated as a non-conductive material.

In this case, changing the weight per unit area has the same effect. However, in practice, it is necessary to consider the stability of the resulting sheet or paper.

The conductive fiber chop that can be used in the present invention is desirably 10 to 200 g per square meter in view of the intended performance of the planar heating element. If the amount is less than 10 g, uniform dispersion of the fiber itself becomes difficult. If the amount exceeds 200 g, the step of impregnating and fixing the resin becomes difficult,
Further, even if a carbon fiber larger than the practical use is used, the performance such as output is not improved, and in many cases, it is simply disadvantageous economically.

The resin to be impregnated in the conductive fiber chop to obtain the conductive heat generating portion of the present invention is, for example, 100 to 2
A thermosetting resin that melts at 00 ° C., is simultaneously impregnated into fibers under the pressure during molding, and cures after a certain period of time,
A thermoplastic resin which is melted at 00 to 200 ° C. and impregnated into fibers by the pressure at the time of molding is also included.

Of course, both may be used in combination.
Further, both may be separated and processed stepwise.

Examples of resins that can be used for this purpose include phenol resins, urea resins, melamine resins, unsaturated polyester resins, polyurethane resins, alkyd resins,
Epoxy resin, silicone resin, and other thermosetting resins, various polyolefin resins, polyester resins,
Polycarbonate resin, polyterpene resin, petroleum resin,
And other thermoplastic resins can be used.

The thermosetting resin may be used in an uncured, uncured or semi-cured state that has not been completely cured. The thermosetting resin is impregnated in a softened or molten state before curing by heating, and then cured to fix the conductive material. Will be transformed.

Further, in order to change the conditions of impregnation and curing, these resins may be mixed or modified, and may be used as long as the above conditions are satisfied.

The maximum temperature of the heat generated by the planar heating element (A) is determined by the heat generation area (or the distance between the electrode strips), the type, shape and content of the conductive fiber used, the softening point of the impregnating resin, and The applied voltage (supplied voltage) is generally determined. However, since the heating area and the applied voltage are naturally determined by the application site, the composition of the conductive fiber chop and the resin for impregnation in the conductive heating section is substantially determined. Can be determined by selecting.

The resin to be impregnated is preferably selected so as to satisfy the following equation.

[0047]

[Formula 4] Flow temperature of impregnated resin in element (A) −steady maximum temperature of element (A)> 30 ° C. (1)

These resins can be used in a single sheet or film, but can also be used in a state of being applied to a sheet or film used on the surface. The latter is simpler and more suitable in the production process.

In the conductive heat generating portion having no PTC function and having a conductive fiber chop impregnated with a resin, an electrode band is provided along at least two opposite edges on one side, respectively. And the conductive heat generating portion are overlapped and closely contacted to form a planar heat generating element (A). Of course, the electrode strips need only be provided in parallel, and do not necessarily have to be along each of the two opposite edges of the surface. In the case of the element (A), when the constant voltage is applied, the smaller the distance between the electrodes, the higher the temperature of the heat generated. On the other hand, when the constant distance between the electrodes,
As the applied voltage is higher within a range where the resin does not melt, higher-temperature heat is obtained.

The number of electrode strip pairs may be one or two or more.
Make them all parallel. For example, A, B, C,
The four electrode strips D are arranged in parallel in this order at an arbitrary interval.
By adjusting the distance between the electrodes with a switch, for example, between A, D, B, C, B, D, and C, the exothermic temperature and exothermic part can be adjusted.

When a voltage is applied between the pair of electrode strips, a current flows between the electrodes and the conductive portion generates heat.
The imprint voltage may be an AC voltage or a DC voltage.

When the surface needs to be electrically insulated,
The closely-connected conductive heating portions of the electrode strip pairs are
Except for the partially exposed portion necessary for the wiring, the entirety of one surface, preferably both surfaces, on which the electrode band pairs are provided, may be covered with an insulating film.

The insulating film used for the sheet heating element is
Any material can be used regardless of its material as long as it can insulate the surface where current is generated and heated.

In the present invention, as the insulating layer (plastic layer), use is made of a film or sheet which does not melt at the maximum temperature of heat generated by the finally obtained sheet heating element, the molding temperature and the pressure. Is good.

A film that melts at the temperature and pressure during molding,
Although a sheet can be used, in such a case, the conductive sheet for generating heat is impregnated and the electric resistance value is lowered. However, in this case, unless the material has a sufficient thickness, electrical insulation on the surface cannot be ensured.

As the surface insulating layer which does not melt at the temperature and pressure during molding, specifically, films and sheets of polyvinylidene fluoride, heat-resistant polyvinyl chloride, various polyesters, polyurethanes and the like can be used.

As the type of melting at the temperature and pressure during molding, polyethylene, polypropylene, polyvinyl chloride, and various other polyolefin-based films and sheets having a lower melting temperature can be used. However, these classifications are based on a molding temperature of 130 to 140 ° C., and if the molding temperature changes, the classification will also change.

Films and sheets of these thermoplastic resins must be selected in consideration of the maximum temperature at which heat is actually generated. For example, when heat is generated at a maximum of 50 to 60 ° C., polyethylene, ethylene-vinyl acetate copolymer,
A thermoplastic resin film or sheet that can be melted and impregnated at a temperature of about 100 ° C., such as a low-melting polyester, can be used.

However, when the heat generation temperature rises to 100 ° C., a heat-resistant thermoplastic resin film or sheet must be used. For example, films and sheets of polyester, polyurethane and the like having a high heat melting temperature can be used.

In this case, the melt impregnation temperature is 140 to 15
It becomes 0 degreeC or more. Even when the heat generation temperature is further increased, a thermoplastic resin film or sheet having a melting temperature higher than the maximum use temperature may be used.

Among these films and sheets, the material whose melting temperature rises due to heat history is more suitable for the purpose. For example, films and sheets of thermoplastic polyurethane, etc., after forming a planar heating element, by actually repeating the heat generation, it has been found that the melting temperature increases, the thermoplastic resin film of the present invention, It is one of the most suitable as a sheet.

Various materials can be selected so as to satisfy the following temperature conditions, for example.

[0063]

[Formula 5] Flow temperature of impregnated resin in element (A) −steady maximum temperature of element (A)> 30 ° C. (1)

[0064]

[Formula 6] Coating temperature of insulating film> Flow temperature of resin impregnated in element (A)> Steady maximum temperature of element (A) (2)

The sheet heating element thus obtained is provided with an appropriate surface in accordance with a use department and a use form in practical use, processed into a required shape, and installed.

The planar heating element made according to the present invention is characterized in that it can be obtained in the form of a thin sheet. That is, there is an advantage in that heat is uniformly generated from the entire surface in the form of a thin film, and further, in the present invention, a flexible planar heating element can be obtained.

There are many places where the immediate heating element is used, such as inner and outer walls of a building, a roof, a floor, and indoor furniture.
It is desirable to form a thin film or a thin plate. Therefore, the sheet heating element used in the present invention has a thickness of 1.5
mm and as thin as possible. When the thickness is 1.5 mm or more, usefulness such as flexibility tends to be weakened.

The present invention is implemented, for example, as follows.
First, determine the size and structure of the sheet heating elements and stack them accordingly. For example, in order from the upper layer, a polyester film to be an insulating layer / a thermoplastic resin (film) to be impregnated
/ Cutting a foil of a fixed width at both ends to serve as electrodes, stacking conductive sheet to generate heat, thermoplastic resin (film) to be impregnated / polyester film.

In this case, when a metal portion is further disposed on the surface, a film having a required thickness may be used in place of the polyester film, and a metal sheet or plate may be disposed outside the film.

After the stacking, one method is to impregnate a thermoplastic resin into a sheet which is subjected to compression molding and heat generation by heating, and at the same time, the upper and lower polyester films are adhered and fixed to form a sheet heating element. In this case, the compression molding temperature must be higher than the melting temperature of the thermoplastic resin to be impregnated and lower than the melting temperature of the polyester film to be the upper and lower insulating layers. Further, the molding of the molded article is performed after at least the surface temperature of the molding machine becomes lower than the melting temperature of the thermoplastic resin.

Another method is to heat the above-mentioned stacked product in advance to a temperature higher than the melting temperature of the thermoplastic resin, to melt the thermoplastic resin, and to obtain a temperature required for cooling, for example, 30 ° C. or less. Between rolls held at a temperature of
This is a method of cooling simultaneously with impregnation.

This method of impregnation through a roll is suitable for large-scale production, but good impregnation cannot be obtained unless the working conditions are precisely set. For this reason, in the case of a small amount, a method of compression molding to obtain a sheet heating element is convenient.

Needless to say, in this step, the polyester film to be the surface insulating layer is previously coated with a thermoplastic resin or a thermosetting resin to be impregnated, or the film is laminated to integrate the surface layer and the resin for impregnation. Can also be used, which is more preferable in terms of simplifying the molding process. In addition, the impregnating resin may be used by impregnating the conductive sheet in advance.

The multiple security mechanism, which forms part of the main element of the invention, is implemented as follows. It consists of a thermocouple (B) that opens and closes contacts (ON / OFF of energization) above and below a certain temperature, and a thermal fuse (B) that melts when held at a certain current value for a certain period of time. It consists of attaching to a planar heating element.

The thermocouple (B) is, for example, a combination of two different metal wires and connecting both ends to form a closed circuit. If there is a temperature difference between two contact points, an electromotive force is generated. The element that generates this thermoelectromotive force and two different thin metal plates that expand and contract greatly due to changes in temperature are bonded together, but the contact is opened and closed using the fact that it bends to one side due to changes in temperature. To do (thermostat)
Is mentioned.

As the former, although it depends on the temperature to be controlled,
For example, copper-constantan, alumel-chromel, platinum-platinum rhodium and the like can be mentioned, and as the latter, bimetals of amber and bronze and those using expansion of mercury can be mentioned. A thermistor using a semiconductor having a large temperature coefficient of electric resistance can also be used by selecting an operating temperature. In the present invention, it is preferable to use the thermostat.

The temperature fuse (C) is a component that melts and breaks to protect circuits and devices when an excessive current flows, and stops and protects the current flow. Examples of such a wire include a lead-tin alloy wire, a brass wire, and a tungsten wire.

The thermocouple (B) and the thermal fuse (C) may of course be combined in plurals.
In practice, each one is economically inexpensive,
Moreover, the safety aimed at by the present invention can be ensured in one way.

The thermocouple and the thermal fuse may be combined with each other separately or may be integrated with each other. For installation, it is cheaper and more convenient to integrate the thermocouple and the thermal fuse.

The system according to the present invention comprises a planar heating element (A) having a PTC function and having a conductive heating portion and an electrode band pair in which a conductive fiber chop is impregnated with resin, and a thermocouple. (B) and a thermal fuse (C), one of the basic systems of the present invention is to provide at least one set of each of the plurality of planar heating elements (A). In principle, the thermocouple (B) and the thermal fuse (C) are combined.

Further, it is possible to divide the plurality of sheet heating element elements (A) into blocks for each of the plurality of sheets and control the blocks by sensing the temperature at one point inside. During operation under normal control, operation is normally performed outside the operating region temperature of the thermocouple and the temperature fuse, and only when abnormal heat is generated, these are operated to ensure safety.

In this case, it is desirable that the thermocouple (B) works at a temperature higher by 10 to 30 ° C. than a normal operating temperature (steady maximum temperature), and that the thermal fuse operates at a temperature higher by 10 to 30 ° C.

That is, when the normal operating temperature (steady maximum temperature) is T ° C., the current interruption temperature T1 of the thermocouple (B) is
Is selected to be in the range of (T + 10) to (T + 30) ° C. Further, the cutting temperature T2 of the thermal fuse (C) is
They are selected so as to be in the range of (T1 + 10) to (T1 + 30) ° C., and they are electrically connected.

The stability in long-term use, which is the greatest goal of the present invention, can be determined by whether or not it has PTC properties. However, in the sheet heating element used in the present invention, a thermocouple (B) and a thermal fuse From the results of the repetition test of the current cutoff without (B), it was found that even with the repetition, the resistance value always increased in the same tendency by heating by the current supply, and there was no tendency to lead to contact destruction.

Although a continuous heat generation test of 30,000 hours was conducted experimentally, there was no change in output and electric resistance before and after the experiment.
Of course, there was no partial heat generation, a change in resistance value, or the like, which is assumed to be a short circuit phenomenon.

When implemented in an actual building, there is a view that it is safer to have PTC performance, that is, a self-control function, in the short term, but in practice, it must be permanently operated during long-term use. Fatigue has occurred in the self-control function itself, and a number of accidents due to short circuits have been reported. The usefulness of the system of the present invention using a sheet heating element that does not intentionally use the PTC function is expected.

Conventionally, when a planar heating element is used for a part of a building, it is often performed with a hot water pipe or the like, but various other materials are known. For example, a nichrome wire is used as a heating element. There are objects rolled on paper and sheets, objects formed by bending pipe-shaped heating elements into planes, and the like, and these various types of materials have been used in various ways.

However, for example, when using a hot water pipe or the like, there are problems such as initial cost, repair, and a long start-up time during operation. If even one break occurs, heat generation stops, so failure easily occurs and repair is difficult. Further, only the portion of the nichrome wire generates heat, and the entire portion is heated by the heat, so that the temperature around the nichrome wire increases, which greatly restricts the use of materials having a risk of thermal deformation and ignition. That is, it is usually difficult to secure insulation by covering with a thermoplastic film or the like which is inexpensive and easy to process.

When a pipe-shaped heating element is used, it is possible to ensure insulation, but it is difficult to bend freely and there is a problem in workability, and it is also a big problem that the cost is high.

By using the planar heating element employed in the present invention, the above-mentioned disadvantages can be solved.

The excellent system of the present invention is suitable for heat insulation and heating of, for example, the interior and exterior walls and floors of buildings, furniture and the like.

[0092]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described based on preferred embodiments. First, the fiber length is 1 to 200 mm, the fiber diameter is 5 to 20 μm, the aspect ratio is 50 or more, and the specific volume is 9 cm.
³ / g or more, only a chopped carbon fiber short fiber chop or a non-conductive fiber short fiber pulp that is not thermally fused is contained in a uniformly dispersed and fixed state.
A rectangular conductive heat-generating portion containing carbon fiber in an amount of 10 to 200 g / m ² in excess of 20% by weight as a carbon fiber, in a state where is impregnated with a cured product of a thermoplastic resin or a thermosetting resin;
An electrode band made of a good conductive metal foil, which is arranged along both end edges of two opposite sides of at least one surface of the heat generating portion, and both of the electrode band pairs are partially exposed such that they can be wired. Except for the wiring portion, the heat generating portion and the electrode band pair are intimately covered and integrated with an insulating film, and at a steady heating temperature, neither the impregnated resin nor the insulating film is melted, and the total thickness is 1.5 mm or less. Exothermic temperature upper limit (maximum temperature reached) 5
No self-temperature control function preset at 0-70 ° C,
Prepare a sheet heating element with excellent flexibility.

A unit in which a power source is connected to the electrode of the wiring portion for energizing the sheet heating element without the self-temperature control function, and a thermostat and a temperature fuse (C) are connected in this order as a thermocouple (B). Connected and energized and de-energized can be controlled by the temperature of the conductive heating part.

The thermostat at this time is 60 to 1
A temperature cutoff at 00 ° C is used, and a temperature fuse (C) made of a metal wire melting at 70 to 130 ° C is used. <Satisfies the relationship of the temperature fuse cutting temperature, and uses the maximum steady-state temperature as the threshold value,
In an emergency, the thermostat and the thermal fuse operate in this order, and a double safety mechanism prevents abnormal heat generation, white smoke, ignition and the like.

[0095]

Next, the present invention will be described in detail with reference to examples. The following examples are based on the preferred embodiments of the invention described above.

Example 1 53 g / m2 (weight: 53 g / m2) of a carbon fiber chop having a fiber length of 3 mm, a fiber diameter of 13 μm, and a specific volume of 9 cm ³ / g or more contained in a short fiber pulp of cellulose fiber. ^Two
45% of conductive mixed paper with fibers uniformly dispersed and fixed
cm × 40 cm, and on both sides, 110 ° C.-12
A thermoplastic film (ethylene / vinyl acetate resin) of the same dimensions which is melted at 0 ° C. is placed one by one, and the width is 10 mm along the opposite edges of one side of the mixed paper in direct contact with the mixed paper. A copper foil having a thickness of 105 μm was placed, and a 100 μm-thick polyethylene terephthalate (PET) film (manufactured by Teijin Limited) was disposed on both outer layers.

This was press-formed at 130 ° C. and 5 kg / cm ² to obtain a sheet heating element. The electric resistance value of this heating element is 15
It was 0Ω. A voltage of 100 V was applied to the heating element.
The surface temperature was 36 ° C after 3 minutes, 51 ° C after 5 minutes, and 6 after 10 minutes.
The temperature reached 5 ° C.

The sheet heating element was sandwiched between calcium silicate plates having a thickness of 10 mm, and a continuous heat generation test was performed. At the start of heat generation, the surface temperature of the calcium silicate plate was 58 ° C. at an applied voltage of 100 V, and the electrical resistance value in the heated state was 148Ω. One week after the start of the continuous heating test, the surface temperature: 5
The electrical resistance value at 9 ° C was 146Ω. No so-called PTC property was observed in this sheet heating element.

A test operation was performed by attaching a thermocouple whose operating temperature was set to 80 ° C. and a temperature fuse whose temperature was set to 100 ° C. to this planar heating element. In normal operation, the maximum temperature is 55 to 60 ° C. without any control, and there is no problem. However, under an impressed voltage of 200 V assuming an abnormal time, the surface temperature reached 80 ° C. and the thermocouple started to operate.

Assuming further heat generation, the thermocouple was removed at a voltage of 200 V, and a cushion was placed on the sheet heating element to continue the heat generation. As a result, the surface temperature reached 100 ° C., and 7 minutes later, the thermal fuse was blown. This test confirmed the operation status of the multiple safety mechanism.

[0101]

According to the present invention, since a system in which a thermocouple and a thermal fuse are combined with a planar heating element including a conductive fiber chop having no PTC function, a conventional planar heating element having a PTC function is used. When a system using a body is used in a building or the like and used stably over a long period of time, it is possible to provide an insulated heating system with excellent stability without abnormal heat generation accident due to short circuit.

Claims (8)

[Claims] 1. A planar heating element (A) having a conductive heating portion and an electrode band pair in which resin is impregnated into a uniformly dispersed and fixed conductive fiber chop having no PTC function. A thermocouple (B) that opens and closes at a temperature of +10 to 30 ° C. higher than a steady maximum temperature reached when a voltage is applied to the electrode strip pair, and a thermal fuse (C) that operates at a temperature higher by +10 to 30 ° C. Combined heat insulation and heating system. 2. The system according to claim 1, wherein in addition to the conductive fiber chop, an element (A) containing non-conductive fibers is used. 3. The system of claim 1 wherein the conductive fiber chops in element (A) are curved carbon fiber chops. 4. The system according to claim 1, wherein the carbon fiber chop contained in the element (A) is 10 to 200 g / m ² . 5. The system according to claim 1, wherein the carbon fiber chop contained in the element (A) is a carbon fiber chop having a length of 1 to 200 mm. 6. The system according to claim 1, wherein a resin to be impregnated is selected so as to satisfy the following equation. [Formula 1] Flow temperature of impregnated resin in element (A) −steady maximum temperature of element (A)> 30 ° C. (1) 7. The system according to claim 1, wherein an element is used in which the conductive heating portion and the electrode band pair are covered with an insulating film so that both of the electrode band pairs are partially exposed. 8. The method according to claim 8, wherein the following two equations are satisfied.
The described system. [Formula 2] Flow temperature of impregnated resin in element (A)-Maximum steady state temperature of element (A)> 30 ° C (1) [Formula 3] Coating temperature of insulating film> In element (A) Flow temperature of impregnated resin> Maximum steady-state temperature of element (A) (2)