JP2000113969A - Flat heater element and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flat heater element having high efficiency. SOLUTION: Heat-resistant resin sheets 2b are vacuum thermo-compression- bonded on both faces of a flat heater element 2a via a hot-melt adhesive to form a flat heater element 2. The flat heater element 2a is made of a conductive woven fabric impregnated with metal grains or carbon grains into a heat- resistant woven fabric, for example, and TPO is used for the resin sheets 2b. If conductive layers are formed on the resin sheets 2b, an electric leakage between the heater element 2a and the conductive layers 2b is detected, and an accident caused by an overcurrent can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet heating element, and more particularly to a sheet heating element having improved thermal efficiency.

[0002]

2. Description of the Related Art Conventionally, a cord type heater (heating wire) and a hot water circulation system have been known as floor heating heaters. The method requires construction time and construction costs, such as plumbing work under the floor, and is difficult to use easily. Accordingly, a heating device using a planar heating element has recently been developed because of its uniform temperature distribution and low cost.

[0003] As a planar heating element, for example, a conductive woven fabric obtained by impregnating metal particles or carbon particles into a heat-resistant woven fabric is known. This conductive woven fabric is used by sealing it with a heat-resistant packaging bag, for example, or by being laminated with a resin sheet such as heat-resistant vinyl chloride.

[0004]

However, the conventional planar heating element has a problem in that thermal efficiency is poor. The reason for the poor thermal efficiency is that there is an air layer between the heating element such as conductive woven fabric and its packaging bag, or the heating element such as conductive woven fabric has irregularities and the resin sheet and conductive woven fabric Because air has entered between, the air expands due to heating,
It is considered that the air layer works as a heat insulating layer.

The present invention has been made in view of the above points, and has as its object to provide a planar heating element having high thermal efficiency.

[0006]

In order to solve the above-mentioned problems, in the present invention, a heat-resistant resin sheet is vacuum-heat-bonded to both surfaces of a sheet heating element with a hot-melt adhesive to form a sheet heating element. Made up the body.

[0007]

FIG. 1 shows an embodiment of the present invention. A sheet heating element 2 is composed of a heating element 2a covered with a heat-resistant resin sheet 2b. As the heating element 2a, a conductive woven fabric (“Heatex” manufactured by Vinyl Heatex Co., Ltd.) in which cloth is impregnated with carbon particles or metal particles is used. As the resin sheet 2b, for example, T
Use PO (thermo plastic olefin) or the like.

The heating element 2a is covered with the resin sheet 2b by vacuum thermocompression bonding. That is, a hot melt adhesive is interposed between the heating element 2a and the resin sheet 2b,
After sealing with a sealing sheet or the like, the inside is evacuated and pressed while heating. Here, the hot melt adhesive is
An adhesive that is solid at room temperature but is heated and melted. Details of the vacuum thermocompression bonding will be described later.

Incidentally, it has been pointed out that a problem when using the planar heating element is that a load is applied to a part of the planar heating element, an overcurrent flows, local overheating occurs, and an accident such as a fire occurs. This is a risk that In the present invention, means for preventing the above situation is provided. Specifically, as shown in FIG. 2, a conductive layer (for example, an aluminum layer) 2c is formed on one or both surfaces of the sheet heating element via a resin sheet 2b, and a gap between the heating element 2a and the conductive layer 2c is formed. A detecting means 6d for detecting an electric leakage is provided. If local overheating occurs, that portion of the resin sheet 2b will melt,
At that portion, the heating element 2a and the conductive layer 2c are short-circuited. This is detected by the detecting means 6d, and when an electric leakage occurs, the power supply to the sheet heating element 2a is stopped to prevent an accident due to an overcurrent.

Next, a method for manufacturing the above planar heating element will be described. The heating element 2a (conductive woven fabric) and the resin sheet 2b are previously processed to a fixed size. If used for floor heating unit, for example 800mm square or 800mm x 16
00 mm. Next, as shown in FIG. 3, the hot melt film 4 is sandwiched between the heating element 2 a and the resin sheet 2 b, overlapped and spot-bonded, and temporarily pressed through the pressure roll 6. As a hot melt film, for example, E
Use a VA film of 50-120 microns. When the conductive layer 2c is formed, an aluminum sheet may be thermocompression-bonded to the resin sheet 2b via the hot melt film 4.

As the hot melt adhesive, a solid hot melt is used in place of the above hot melt film, which is melted and applied to both surfaces of the heating element 2a using a roll coater or the like. Is also good.

Next, the sheet heating element 2 coated with the hot melt is preheated by using, for example, a far-infrared heater 8 or the like. This preheating is not an essential requirement, but by doing so, the time for vacuum thermocompression bonding described below can be reduced.

Thereafter, the sheet heating element 2 is connected to the vacuum thermocompression bonding apparatus 1.
Vacuum thermocompression bonding using 0. As shown in FIG. 4, the vacuum thermocompression bonding apparatus 10 includes a substrate 12 having a plurality of ventilation holes 12a.
And a vacuum chamber 14, 1 provided below the substrate 12.
6, 18 are provided. The chamber 14 is connected to a pump 20, and the chambers 16 and 18 are connected to a pump 22. The sheet heating element 2 is carried in on the substrate 12, and the sealing sheet 26 is cut thereon. A heater or the like (not shown) for keeping the temperature may be provided on the upper surface of the substrate 12.

The sealing sheet 26 is flexible and has a configuration in which a sheet heating element 28 is sandwiched between insulating sheets 30 as shown in FIG. If a fluororesin (for example, “Teflon”) or a silicon resin (silicone) is used as the insulating sheet 30, not only the insulating property but also the heat resistance is excellent, and the releasability without sticking to the hot melt adhesive is obtained. good.

When the sheet heating element 2 is conveyed to the vacuum thermocompression bonding apparatus 10, the sheet heating element 2 is covered with the sealing sheet 26. This may be performed manually, or may be performed automatically by providing a suitable elevating device or expanding device and attaching the sheet 26 to these devices. At this time, pumps 20 and 22
Is driven, and the pressure in the vacuum chambers 14, 16, 18 is reduced. Since the sealing sheet 26 covers the sheet heating element 2, the air between the sealing sheet 26 and the substrate 12 is deaerated through the ventilation holes 12a. As a result, a negative pressure is applied between the substrate 12 and the sealing sheet 26, and the sheet heating element 2 is uniformly pressed over the entire surface by a large force of vacuum pressure, so that the sheet heating element 2 comes into close contact with the hot melt sheet 4. At this time, the planar heating element 26
The hot-melt sheet 4 is completely melt-bonded to the fiber portion of the planar heating element as well.

When a long sheet heating element is manufactured, if the entire length cannot be covered with the sealing sheet 26, the long sheet heating element is exposed from the sealing sheet 26. Since there is a risk that air will escape from the exposed part,
In order to cover the portion and maintain high airtightness, an end portion of the sealing sheet 26 in contact with the sheet heating element 2 is covered with an auxiliary sheet. Then, the sealing sheet 26 is sucked by the main chamber 14, and the auxiliary sheet is sucked by the sub-chambers 16 and 18. Then, the auxiliary sheet is more strongly adsorbed by the sub-chambers 16 and 18, and the portion covered with the sealing sheet is kept airtight. The auxiliary sheet may cover the entire sealing sheet 26, or may cover only the portion where the sealing sheet 26 contacts the planar heating element 2.

After vacuum thermocompression bonding, an extrusion roller (not shown)
Thereby, the sheet heating element 2 is carried out. At this time, the pumps 20 and 22 may be driven in reverse to blow out air from the ventilation holes. Then, the sheet heating element 2 and the substrate 12
By forming an air layer between the heat generating member and the heat generating member, friction can be reduced, and the sheet heating element 2 can be quickly carried out.

Thereafter, the sheet heating element 2 is cooled to solidify the hot melt adhesive. That is, as shown in FIG.
The sheet heating element 2 is cooled by sandwiching it between cooling plates 34. Of course, other appropriate cooling methods, such as blowing cold air to the sheet heating element 2, may be used.

As described above, by performing vacuum thermocompression bonding, air between the heating element and the hot melt adhesive (particularly air interposed between the fiber portion and the uneven portion of the heating element) is removed and adhered closely. Can strongly fix the heating element,
Thereby, the durability of the heating element can be improved. Further, by removing air from the heating element, the thermal efficiency is significantly improved. In addition, if a flexible resin sheet such as TPO is used, a flexible planar heating element can be realized, and its workability is improved.

The area of use of the above planar heating element is wide, for example, it can be used not only for floor heating, but also for wall heating in combination with wallpaper and the like, and for surrounding heating when used for toilet walls. Further, it is suitable as a snow melting heater laid on a roof or a road in a snowfall area.

A flexible TPO as a resin sheet
By using such a material, a flexible planar heating element can be obtained, and a curved surface shape can be formed. For example, it can be used as a heater for keeping hot water by laying it on the inner peripheral surface or bottom surface of a bathtub. In cold regions, it can be used as a heater for keeping food warm by burying it in roof tiles and using it for snow melting, or arranging it on the inner peripheral surface of a feed tub for livestock.

[0022]

As described above, according to the present invention,
A planar heating element having high thermal efficiency can be provided.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a sheet heating element showing an example of the present invention.

FIG. 2 is a sectional view showing another example of the present invention.

FIG. 3 is a manufacturing process diagram of a sheet heating element.

4A and 4B show an example of a vacuum thermocompression bonding apparatus, wherein FIG. 4A is a plan view and FIG. 4B is a cross-sectional view taken along line AA of FIG.

FIG. 5 is an enlarged sectional view of a sealing sheet.

[Explanation of symbols]

 2 planar heating element 2a planar heating element 2b resin sheet 3c conductive layer

Claims (6)

[Claims] 1. A sheet heating element characterized in that a heat-resistant resin sheet is thermocompression-bonded to both sides of a sheet heating element via a hot melt adhesive. 2. The sheet heating element according to claim 1, wherein the sheet heating element is a conductive woven cloth obtained by impregnating metal particles or carbon particles into a heat-resistant woven cloth. 3. The resin sheet according to claim 1, wherein the resin sheet is TPO.
Or the planar heating element according to 2. 4. The sheet heating element according to claim 1, wherein a conductive layer is formed on the resin sheet. 5. A sheet heating element in which a sheet heating element is covered with a resin sheet having heat resistance, wherein a conductive layer is formed on the resin sheet. 6. A sheet heating element is sandwiched between two heat-resistant resin sheets via a hot-melt adhesive and overlapped, and the overlapped one is disposed between a sealing sheet and a substrate. A method for manufacturing a sheet heating element, wherein the resin sheet is vacuum-thermocompressed to the sheet heating element while evacuating and heating air between the sheet and the substrate.