JP5753310B1 - Fluorine resin film sheet heater - Google Patents

Abstract

The present invention provides a planar heater that eliminates temperature unevenness on the surface of the planar heater during heating and that can efficiently perform more stable heating without damaging the planar heater. SOLUTION: A sheet-like heating element 3 in which a lead wire 2 is connected to a terminal portion connected to a conductive heating element 1, and the entire surface of at least one side of the conductive heating element 1, or the conductive heating element 1. A low thermal expansion resin layer P having a thermal expansion coefficient of 8 to 10-5 / ° C. or less is provided on the entire surface of at least one surface of the sheet-like heating element 3 including the terminal portion, and can be heat-sealed from both surfaces. A heat diffusion material layer is provided on each surface of the fluororesin layer A4, which is sandwiched by the fluororesin layer A4 and heat-sealed, and both surfaces can be heat-sealable. A planar heater provided with another fluororesin layer B that can be worn. [Selection] Figure 2

Description

  The present invention relates to a planar heater for heating a liquid or the like.

  A heating element composed of a linear or sheet metal is disposed between two heat-sealable multilayer polyimide films, and these are heat-bonded to form a heat-sealable multilayer polyimide in the space excluding the metal of the heating element. A planar polyimide heater filled with a film is described in Patent Document 1, and an insulating heater composed of heating wires separated from each other and fluororubber obtained by integrally molding the heating wires is described in Patent Document 2. As is known.

Further, in Patent Document 3, a conductive heat generating wiring (heat generating layer) is sandwiched between a ceramic intermediate insulating layer and a surface insulating layer, and a heat diffusion layer is provided on the surface insulating layer and the surface of the ceramic intermediate insulating layer. The layer describes a heating element provided with a substrate.
Further, as described in Patent Document 4, a thermoplastic polyimide sheet is thermocompression bonded to both surfaces of a planar heating resistor, and a metal plate is thermocompression bonded to the surface of one of the thermoplastic polyimide sheets. A sheet in which a heater element made of a patterned conductor film is laminated with an insulating film and a film having good heat conduction is formed on one insulating film as described in Patent Document 5 Heaters are known.

JP 2004-355882 A JP-A-11-219776 Japanese Patent Laid-Open No. 11-329677 Japanese Patent Laid-Open No. 04-141979 JP 2004-265654 A

According to the heater described in Patent Document 1, when polyimide is used, the acid resistance, alkali resistance, and solvent resistance of the polyimide are not good, and durability is particularly a property related to these under heating conditions. Therefore, there is a concern that the entire heater will have a short life.
In addition, impurities in polyimide may dissolve or disperse in the liquid to be heated (Contamination), especially sensitive to contamination by impurities such as semiconductor manufacturing-related, pharmaceutical / bio-related, direct heating of blood and chemicals, etc. When obtaining a liquid to be heated, a heater using polyimide cannot be used.
In addition, the surface of the sheet-like heater is formed with a pattern of the shape of a heating element to be energized, that is, a pattern with unevenness heated to a high temperature reflecting the arrangement of heating wires or the like constituting the heating element, In particular, a place where the temperature is locally high, that is, a heat spot is formed.
Formation of such a heat spot means that unevenness occurs in the heating temperature of the heater surface. Then, as it is used, the resin portion on the surface where the heating temperature is high, such as the surface layer of the planar heater, is locally deteriorated or partially melted. Moreover, due to the thermal expansion of the resin portion or the like, due to the difference in the coefficient of thermal expansion from the low temperature portion, the entire heater will wave when repeatedly used. In addition, depending on the material to be heated, there is a concern that the heating temperature may partially increase, causing problems such as deterioration of the material to be heated itself.
In addition, when the surface temperature is highly uneven and when heated to a temperature that denatures the object to be heated even partially during use, the purpose of heating is not to heat the object to be heated uniformly. May not be achieved. In particular, when it is necessary to heat the object to be heated at a relatively low temperature and uniformly, such a trouble occurs.
Therefore, in order to avoid these troubles, the heating temperature at a locally high temperature does not reach a melting temperature, or the power supplied to the heater is suppressed to lower the heating temperature, Ingenuity in use, such as reducing the rate of temperature rise during heating, was required.
In addition, as shown in Patent Document 2, when a heating element is put in a mold made of fluororesin, the resin layer formed by the mold is thick, and heat transfer is difficult in the thickness direction of the resin layer. It is difficult to dissipate heat to the outside, resulting in a low heating temperature, resulting in a heating device that is not energy efficient. In addition, the planar heater becomes larger than necessary.
In addition, due to molding, it is difficult to reduce the size of the heating device, and since the wiring pattern of the heating element is limited, uniform heat generation is also difficult.

According to the means described in Patent Documents 3 to 5, although the object to be heated is uniformly heated, a surface for radiating heat such as metal is formed on the outer surface of the heater. Depending on the substance, the metal surface may be deteriorated.
In addition, even when the resin sandwiching the heating element has good temperature stability, as in the invention described in Patent Document 1, when using polyimide, the acid resistance, alkali resistance, and solvent resistance of the polyimide are Is not good, and in particular, it is inferior in durability as a property relating to these under heating conditions, so there is a concern that the entire heater may have a short life. In addition, impurities in polyimide may dissolve or disperse in the liquid to be heated (Contamination), especially sensitive to impurities such as semiconductor manufacturing-related, pharmaceutical / bio-related, direct heating of blood and chemicals, etc. When obtaining a liquid to be heated, a heater using polyimide cannot be used.
Furthermore, the use of a ceramic layer may result in a heater that is thicker than necessary.
It is also conceivable to provide a sheet heater by providing two layers of fluororesin layers on both sides of the sheet heating element and providing a heat diffusion material layer between the two fluororesin layers. In this case, since the thermal expansion coefficient of the fluororesin is relatively large with respect to the thermal expansion coefficient of the sheet-like heating element, the sheet-like heating element is the same even if the fluororesin layer expands or contracts due to temperature fluctuations. As a result, peeling occurs between the sheet-shaped heating element and the fluororesin layer, or the sheet-shaped heating element expands and contracts as the fluororesin layer expands and contracts. There is a possibility that wrinkles may occur in the planar heater due to the force applied.
In particular, when this planar heater is used for liquid heating at a high temperature close to 300 ° C., the fluororesin layer in the vicinity of the heating element is softened, and the amount of expansion / contraction is increased. The arrangement (pattern) collapsed, and there was a possibility of short circuit due to contact between the heating wires or between the heating wires and the leads.
When the heat is further generated at a high temperature, the fluororesin that is in direct contact with the sheet-like heating element starts to melt, and the sheet-like heating element and the heat diffusion layer come into contact with each other, which may cause a short circuit.
In addition, it is difficult to quickly dissipate the heat from the surface of the sheet-like heating element after the start of heat generation, and the sheet-like heating element itself is excessively heated, but it is difficult to sufficiently heat the outside immediately. There was a possibility.

The present invention is for solving the above-described problems, and specifically, is as follows.
1. A sheet-like heating element in which a lead wire is connected to a terminal portion connected to the conductive heating element;
Low heat coefficient of thermal expansion of 8 × 10 ⁻⁵ / ° C. or less on the entire surface of at least one side of the conductive heating element or the entire surface of at least one side of the sheet-like heating element including the conductive heating element and the terminal portion. Providing an expandable resin layer;
It is sandwiched and heat-sealed by the fluororesin layer A that can be heat-sealed from both sides,
Furthermore, a heat diffusion material layer is provided on each surface of the fluororesin layer A that can be heat-sealed on both sides,
Another fluororesin layer B that can be heat-sealed is further provided on the surface of the heat diffusion material layer.
Surface heater.
2. The planar heater according to claim 1, wherein the low thermal expansion resin layer contains a resin having a melting point of 200 ° C or higher.
3. 3. The planar heater according to 1 or 2, wherein the low thermal expansion resin layer is a layer containing one or more of a polyamide resin, a polyimide resin, a polyether ether ketone resin, and a polyphenylene sulfide resin.
4. At least one of the two fluororesin layers A that can be heat-sealed to each other and / or at least one of the heat-sealable fluororesin layers B provided on the respective surfaces of the heat diffusion material layer Is a layered heater according to any one of 1 to 3, which is a layer formed by laminating a plurality of heat-sealable fluororesin films and heat-sealing them.
5. The planar heater according to any one of 1 to 4, wherein a portion where the lead wire is connected to the terminal portion connected to the conductive heating element is covered with a heat-sealing material in advance.
6). The sheet heater according to any one of 1 to 5, wherein the sheet-like heating element and the end surface of the heat diffusion material layer are sealed with the fluororesin layers A and B.
7). The fluororesin layers A and B may be made of the same material or different materials, and are made of FEP (tetrafluoroethylene / hexafluoropropylene copolymer) and / or PFA (perfluoroalkoxy fluororesin) 1 The planar heater in any one of -6.
8). The planar heater according to any one of 1 to 7, wherein the heat diffusion material layer is a sheet or foil selected from metal, graphite, ceramics, and resin.
9. The planar heater according to any one of 1 to 8, having a structure in which both sides and the entire circumference of the heat diffusion material layer are covered with the fluororesin layers A and B.
10. The planar heater in any one of 1-9 whose thickness of this fluororesin layer A and B is 0.025-3.0 mm mutually independently.
11. One or more temperature sensors are embedded between one or more of the low thermal expansion resin layer and the fluororesin layers A and B, and between the low thermal expansion resin layer and the fluororesin layer A. The planar heater according to any one of 10.
12 One or more temperature sensors are provided between any of the plurality of layers constituting the low thermal expansion resin layer and the plurality of heat-sealable fluororesin films constituting the fluororesin layers A and B. Item 12. The planar heater according to Item 11.
13. Where desired, the sheet heating element in which the lead wire is connected to the terminal portion connected to the conductive heating element, where the lead wire is connected to the terminal portion in advance, is covered with a heat-sealing material.
Low heat coefficient of thermal expansion of 8 × 10 ⁻⁵ / ° C. or less on the entire surface of at least one side of the conductive heating element or the entire surface of at least one side of the sheet-like heating element including the conductive heating element and the terminal portion. Providing an expandable resin layer;
It is sandwiched and heat-sealed by a fluororesin layer A that can be heat-sealed from both sides,
Furthermore, a heat diffusion material layer is provided on each surface of the fluororesin layer A that can be heat-sealed on both sides,
A step of providing another fluororesin layer B that can be thermally fused on the surface of the heat diffusion material layer;
Manufacturing method of planar heater.

According to the planar heater of the present invention, since it has a heat diffusion material layer, even when the conductive heating element is extremely thin, deformation due to resin shrinkage during the heat fusion process by heating the resin during manufacturing. The force to be suppressed is suppressed by the heat diffusion material layer that is pressure-bonded to the resin, so that it is not transmitted to the conductive heating element itself. Therefore, since the planar heater does not deform or warp in a wave shape, it can be accurately a planar planar heater. Therefore, a stable and constant shape can be obtained, and even when immersed in a liquid to be heated, the planar heater can be surely completely immersed.
Further, by having the thermal diffusion material layer, the heat generated in the sheet-like heating element is quickly absorbed by the thermal diffusion material layer once, and the thermal diffusion material layer itself is uniformly heated. Since heat is radiated from the heated heat diffusion material layer to the surface of the planar heater, the surface of the planar heater can be uniformly heated as a result. As a result, it is possible to prevent the heating temperature from being excessively increased with respect to each layer constituting the planar heater, particularly a layer made of resin, as compared with the case of heating with unevenness without using the heat diffusion material layer.
The liquid to be heated can be heated evenly, and heating is performed under a desired heating condition such as applying a higher power to obtain a quick heating rate or heating at a lower power with a gentle heating rate. be able to. At this time, the resin portion of the planar heater is not deteriorated or melted by heating at an excessively high temperature.
By adopting heat-sealable fluororesin layers A and B, each layer can be fixed more securely, and by making the outermost layer a fluororesin layer B, the acidic, alkaline, aqueous solution, and organic of the liquid to be heated Even when it is used by directly immersing various properties such as a solvent solution, it is stable and does not deteriorate, and as a result, the life of the planar heater can be extended.
In addition to these effects, the external force acting on the heating wire when the fluororesin layer thermally expands and contracts during production or use can be significantly reduced, so that the pattern of the heating wire can be prevented from being collapsed, and as a result Since it is possible to prevent the wiring and lead wires to be connected from being short-circuited, they can be used stably for a long time even at a high temperature exceeding 300 ° C.
Further, even when the fluororesin is dissolved during high-temperature heating, the sheet-like heating element does not come into contact with the heat diffusing material, which is safe.
Furthermore, since heat can be quickly radiated to the outside of the sheet-shaped heating element, the sheet-shaped heating element itself is not excessively heated after the start of heating, and the resistance value of the sheet heater does not increase greatly. The object to be heated can be heated for a long period of time safely and securely.

The figure which shows the sheet-like heating element covered with the low thermal expansion resin Front view of sheet heater Longitudinal cross section of planar heater The figure which shows the laminated structure of a sheet-like heating element and the fluororesin layer A Connection between conductive heating element and lead wire Diagram showing laminated structure of planar heater Layout of conductive heating element in sheet heating element Diagram showing usage of planar heater The figure which shows the structure of the planar heater used in the Example

The planar heater of the present invention is a heater for heating an object to be heated by, for example, putting it into the object to be heated, and is manufactured by thermally fusing a fluororesin layer by having a thermal diffusion material layer. Sometimes, deformation or alteration due to irregular shrinkage of the fluororesin itself can be prevented, and even if the fluororesin is dissolved by heating, if the heat resistance of the low thermal expansion resin layer is sufficient, the sheet heating element is directly It is possible to prevent contact with the heat diffusion material layer.
In addition, since the sheet heater can generate heat uniformly, the object to be heated is not partially heated at an excessively high temperature. In addition, since the temperature sensor can be embedded inside, it is possible to precisely control the heating temperature of the object to be heated.
The constituent members and structure of the planar heater of the present invention will be described below.

(Sheet heating element)
The sheet-like heating element in the present invention includes a conductive heating element, a terminal portion connected to the conductive heating element, and a lead wire connecting portion connected to the terminal portion.
The conductive heating element is composed of a sheet or thin film pattern made of a material that generates heat by a known electric resistance, such as copper, stainless steel, a metal such as an alloy of nickel and chromium, a ceramic such as silicon carbide, or carbon, or a thin wire. The overall shape of the conductive heating element, the pattern, the thickness of the heating line, the width of the pattern, and the like can be appropriately adjusted based on the target heating temperature, the size of the planar heater, and the like.
In particular, when forming as a thin film, the pattern may be provided in advance on one side of the fluororesin sheet to be the fluororesin layer A in the present invention as desired.

The terminal portion is for connecting the lead wire to the conductive heating element, and may be formed integrally with the conductive heating element, or may be joined and connected to the end of the conductive heating element. In any case, it is necessary to have a shape and structure for connecting to the lead wire.
Usually, the lead wire is covered with an insulating material, but the insulating material is peeled off at the connection portion with the terminal portion. Therefore, it is possible to cover the terminal portion of the sheet-like heating element and the lead wire of the present invention, in particular, the portion where the insulating material is peeled, with the same material as the fluororesin layer A in advance. In this case, it is not necessary to coat again with the fluororesin layer A thereafter.

(Low thermal expansion resin layer)
The low thermal expansion resin layer in the present invention is a resin layer having a thermal expansion coefficient of 8 × 10 ⁻⁵ / ° C. or less, more preferably 5 × 10 ⁻⁵ / ° C. or less, and is made of a material having excellent heat resistance. Is preferred. As a result, when the fluororesin layer expands and contracts during the manufacture or use of the planar heater, a force accompanying expansion and contraction is directly applied to the sheet heating element, and bending and wrinkles are generated in the sheet heating element. Can be prevented.
In particular, when this planar heater is used for liquid heating at a high temperature close to 300 ° C., the fluororesin layer in the vicinity of the heating element is softened and the amount of expansion / contraction is increased, and as a result, the original heating wire generated as a result. It is possible to prevent the arrangement (pattern) of the substrate from being broken and eventually short-circuited.
Moreover, even if the adhesiveness between the sheet-like heating element and the fluororesin layer A is not sufficient, this adhesiveness can be improved by adopting a layer having good adhesiveness as a low thermal expansion resin layer. The sheet heating element does not separate from the fluororesin A even during high temperature heating.
In order to obtain such a low thermal expansion resin layer, for example, by adding a large amount of non-conductive inorganic filler to a resin such as polyolefin, the insulation as an inorganic filler-containing resin layer is maintained and the thermal expansion coefficient is lowered. However, the resin material itself having a low coefficient of thermal expansion can be selected and used.
Furthermore, among these resins having a low coefficient of thermal expansion, in order to have excellent heat resistance, can be heated at higher temperatures, and have excellent adhesion to the fluororesin layer, it is higher than fluororesin. It is preferable to employ a resin material containing at least one of a polyamide resin, a polyimide resin, a polyether ether ketone resin and a polyphenylene sulfide resin having a melting point, preferably 200 ° C. or higher. By adopting such a heat-resistant resin, when the sheet heater is heated to a high temperature, the fluororesin layer A is not directly melted by the heat from the sheet-like heating element. The sheet-like heating element does not directly contact the heat diffusing material layer, and the thermal conductivity can be improved.
Further, each of the low thermal expansion resin layers may be a layer composed of one or more layers, and in the case of a plurality of layers, the materials may be the same composition material or different composition materials.
The low thermal expansion resin layer is provided on one or both surfaces of the conductive heating element, or on one or both surfaces of the sheet-like heating element including the conductive heating element and the terminal portion. When it is used for the purpose to do, it is necessary to provide on both sides so that a sheet-like heating element may not touch a heat diffusion material layer directly.

(Fluorine resin layers A and B)
The fluororesin layer A in the present invention is a layer formed between the sheet-like heating element and the heat diffusion material layer, and the fluororesin layer B is a heat diffusion material layer with respect to the fluororesin layer A. It is a layer that is sandwiched and stacked.
The fluororesin layers A and B usable in the present invention are FEP (tetrafluoroethylene / hexafluoropropylene copolymer), PFA (perfluoroalkoxy fluororesin), PCTFE (polychlorotrifluoroethylene), etc., respectively. Can be selected and used in consideration of suitability according to the type of object to be heated, heating temperature, and the like. Among them, it is preferable to be composed of FEP (tetrafluoroethylene / hexafluoropropylene copolymer) and PFA (perfluoroalkoxy fluororesin).
However, in the present invention, in order to heat-seal the fluororesin, it is necessary to employ a fluororesin having the property of being heat-sealable.
Different resins can be used between the fluororesin layers A and B, or the same resin can be used. Similarly, each of the two fluororesin layers A and the two fluororesin layers B can be composed of a plurality of resins. However, it is preferable that all the fluororesin layers are made of the same resin in terms of excellent adhesion at the time of fusion and dimensional stability at the time of heating.
Moreover, since the present invention has two fluororesin layers A and two fluororesin layers B, the two fluororesin layers A are preferably the same resin, and the two fluororesin layers B are the same resin. Is preferred.

The fluororesin layers A and B that can be used in the present invention may be composed of one film, but they are integrated by heat-sealing a plurality of films made of the same resin or different resins. It may be configured as a layer. The thickness of each layer is 0.025 to 3.0 mm, preferably 0.03 to 2.0 mm, and more preferably 0.05 to 1.0 mm. If the thickness is less than 0.025 mm, a planar heater having sufficient strength cannot be obtained, or the conductive heating element or the heat diffusion material layer may be exposed on the surface during handling of the planar heater. Electrical insulation between the heat generating element and the heat diffusion material layer may be insufficient, which is not preferable. If it exceeds 3.0 mm, heat transfer from the sheet-like heating element to the heat diffusion material layer and heat dissipation from the heat diffusion material layer to the surface heater surface are likely to be hindered, which is not preferable.
Moreover, the size (length and width, not thickness) of the fluororesin layers A and B may be the same, and either the length or width of the fluororesin layer B is longer than the length of the fluororesin layer A. Longer both are preferable in that each constituent material of the planar heater sandwiched between the two fluororesin B layers is surely sealed and the side surface of the planar heater is reliably sealed.
The fluororesin layers A and B are preferably larger than the sheet-like heating element and the heat diffusion material layer, respectively. In that case, the sheet-like heating element and the low thermal expansion resin layer, or the fluororesin layer from the end of the sheet heater of the present invention to the end face of the heat-diffusing material layer without protruding from the sheet-like heating element or the heat diffusion material layer A and B are sealed by means such as heat fusion and adhesion, and the liquid to be heated reacts with the sheet heating element or the heat diffusion material layer during use, or the sheet heating element or the heat diffusion material. The heated liquid is not contaminated by the layer.
When the two fluororesin layers A and / or the two fluororesin layers B are composed of a plurality of films, the layer configuration of the films constituting the two fluororesin layers A is mainly focused on the conductive heating element. It is preferable that it consists of a material. The same applies to the two fluororesin layers B.

When both the fluororesin layer A and the fluororesin layer B are composed of two or more films, when two or more PFA films, two or more FEP films are stacked, or when a PFA film and an FEP film are stacked, Any one of them can be laminated on the conductive heating element side.
Further, when both the fluororesin layer A and the fluororesin layer B are composed of three films, for example, a film composed of PFA, FEP and PFA can be sequentially stacked, or a film composed of FEP, PFA and FEP can be sequentially stacked.
The higher the thermal conductivity of the fluororesin layers A and B, the more the heat from the sheet-like heating element is transferred. Therefore, if necessary, in consideration of insulation and chemical resistance, inorganics such as mica and silica are used. A substance can be contained in the fluororesin layers A and B.

(Heat diffusion material layer)
In the heat diffusing material layer in the present invention, the heat generated from the conductive heating element is quickly conducted and diffused over the entire surface of the heat diffusing material layer, and further, the heat is absorbed from the entire heating surface of the planar heater, and this is dissipated. Along with this function, the planar heater is maintained in a predetermined shape against the shrinkage force of these resins when the fluororesin layers A and B are heat-sealed at the time of manufacturing the planar heater. , A function to prevent warping is required.
As such a heat diffusion material layer, a material having a high thermal conductivity, that is, a metal such as gold, silver, copper, iron, stainless steel, aluminum, graphite or ceramic powder, fiber, sheet, foil, In addition to a plate-like or sintered material, for example, a sheet made of a resin containing a large amount of an inorganic substance such as a metal compound such as titanium oxide, silica, or alumina or a metal powder can be employed. Also at this time, it can be employed in accordance with the use of the planar heater, the heating capacity, and the like. Of these, those made of metal or graphite are preferred.

The thermal diffusion material layer is required to have a size necessary for sufficiently absorbing the heat generated from the conductive heating element and dissipating the heat to the outside through the fluororesin layer B. In addition, it is necessary that the fluororesin layers A and B have a size within a range in which sufficient adhesive strength can be ensured when the heat diffusion material layer is sandwiched and heat-sealed.
That is, the heat diffusion material layer made of metal, graphite sheet or the like cannot exhibit sufficiently high adhesive force with the fluororesin layers A and B unless special pretreatment is performed in view of the material. . Therefore, in order to ensure sufficient adhesive strength when the fluororesin layers A and B are heat-sealed with the thermal diffusion material layer interposed therebetween, all of both sides and the entire circumference of the thermal diffusion material layer are the fluororesin layer A. And a structure covered with B. By having such a structure, the fluororesin layers A and B are thermally fused with sufficient adhesive force even through the thermal diffusion material layer, and at the same time, a part of the thermal diffusion material layer is a planar heater. Therefore, there is no risk of alteration such as corrosion due to non-heated substances.

(Temperature sensor)
As the temperature sensor used in the present invention, known temperature sensors such as various thermocouples and various resistance thermometers can be used, and the measurement range is planned according to various uses of the planar heater of the present invention. It is necessary to make it a range.
However, since it is embedded in the plurality of layers constituting the low thermal expansion resin layer, the fluororesin layer A and / or B, a thin shape is preferable in order to make the shape of the planar heater of the present invention planar. . When embedding in these layers, one or more temperature sensors of temperature sensors are inserted between a plurality of films constituting these layers, and then these films are integrated to form fluorine. The resin layer A and / or B is preferable. One or more temperature sensors may be provided between the low thermal expansion resin layer and the fluororesin layer A.
One temperature sensor may be used in the present invention unless otherwise specified.
Further, as a place to be provided, a place close to the object to be heated is preferable in terms of more accurately controlling the temperature of the object to be heated, and therefore it is necessary to embed it in the fluororesin layer B. On the other hand, it is necessary to embed in the fluororesin layer A in order to monitor the heat generation state of the conductive heating element. Therefore, when the temperature sensor is provided in the present invention, it is necessary to embed it in the fluororesin layer A and / or B in advance at the stage of manufacturing the planar heater of the present invention.

(Use)
The planar heater of this invention can be used for the use which heats to arbitrary temperature in the range of the temperature which does not soften the low thermal expansion resin layer and the fluororesin layer A or B. Such applications include chemical reaction processes in the chemical industry, manufacturing processes in the food industry, food and beverage warming, blood warming, chemical and water heating, chemical manufacturing, chemicals in the manufacturing process of electronic materials and semiconductors, It can be used for applications such as heating of a cleaning agent, heating in a room or in a car, snow melting, heat retention in livestock, heat retention in a water tank, chairs, seats, and the like. It cannot be used in gases or liquids that alter or decompose fluorine resin such as fluorine gas, chlorine trifluoride, or oxidizing agent.
At this time, the liquid can be heated by being immersed in the liquid, or the atmosphere can be heated by being placed in the atmosphere. Further, the two plate-like objects can be heated by sandwiching the planar heater between the two plate-like objects.
In particular, when the planar heater of the present invention is used, the planar heater itself does not change in quality and does not generate gas or impurities. Therefore, in applications where it is necessary to prevent the contamination of impurities, atmosphere, water, chemical solution , Blood and detergent can be kept warm and heated directly.
Since the surface heater of the present invention uniformly heats the heater surface without generating a heat spot that only partially heats, temperature control is strictly performed, and the heater is heated to a temperature higher than a predetermined temperature. Therefore, it can be effectively used in medical applications and the like that must be prevented.

(Example)
Hereinafter, the present invention will be described with reference to examples.
1 includes a conductive heating element 1 used in the present invention, a terminal portion 1a connected to the conductive heating element 1, and a connection portion 2a between the lead wire 2 and the terminal portion of the lead wire 2. The sheet-like heating element 3 is indicated by a broken line. A low thermal expansion resin layer P is laminated on one side of the sheet-like heating element 3.
In this figure, the low thermal expansion resin layer P is laminated on one side of the sheet-like heating element 3, but it may be laminated on both sides. When they are laminated on both sides, they can be integrated by a known means such as heat fusion or adhesion, with a sheet-like heating element sandwiched between two low thermal expansion resin layers.
When the low thermal expansion resin layer is made of polyamide or the like, the precursor may be used to sandwich the sheet-like heating element.

FIG. 2 includes a conductive heating element 1 used in the present invention, a terminal portion 1a connected to the conductive heating element 1, and a connection portion 2a between the lead wire 2 and the terminal portion of the lead wire 2. The sheet-like heating element 3 is indicated by a broken line. Moreover, the low thermal expansion resin layer P shown in FIG. 1 is indicated by a broken line.
This sheet-like heating element 3 includes a fluorine resin layer A4 on both surfaces including the low thermal expansion resin layer P, and these are fused together to be integrated with each other without being exposed to the outer surface. It will arrange | position in resin layer A4. In FIG. 2, since the entire sheet-like heating element is covered with one low thermal expansion resin layer P and two fluororesin layers A4, the shape of the fluororesin layer A4 is substantially reverse convex. Although it is a shape, as long as the electroconductive heat generating body 1, the terminal part 1a, the connection location 2a, and the lead wire 2 are coat | covered, arbitrary shapes may be sufficient.
If only the conductive heating element 1, which is a portion excluding the terminal portion 1 a and the lead wire 2, is covered with the fluororesin layer A from the sheet-like heating element 3, the terminal portion 1 a, the connection location 2 a and the lead wire 2 are connected. A material similar to that of the separately prepared fluororesin layer A is coated so as to be integrated with the fluororesin layer A.

  A cross section in the thickness direction of the member formed by coating the sheet-like heating element with the fluororesin layer A4 shown in FIG. 2 is shown in FIG. As clearly shown in FIG. 3, the sheet-like heating element 3 and the low thermal expansion resin layer P need to be surely present inside the fluororesin layer A4 without protruding outside the fluororesin layer A4. .

An example of a laminated structure of the sheet-like heating element and the fluororesin layer A is shown in FIG.
In FIG. 4, the terminal portion 1 a is a wide flat portion formed continuously with the conductive heating element 1, and a connection portion 2 a with the terminal portion 1 a extending from the lead wire 2 is overlaid thereon. You may connect the terminal part 1a and this connection location 2a by soldering etc. in this overlapped state.
Of course, the structure is not limited to the structure shown in FIG. 4. A metal member for a terminal is connected to the conductive heating element 1 by a known means such as solder or caulking, and the connection portion 2 a of the lead wire 2 is connected to the terminal. The lead wire 2 can be connected to the conductive heating element 1 in such a manner.

An example of the connection structure between the conductive heating element 1 and the lead wire 2 is shown in FIG.
The terminal portion 1a connected to the conductive heating element 1 is connected to the connection portion 2a from which the insulating coating 2b of the lead wire 2 is peeled off. Here, the terminal portion 1a and the connection portion 2a are both sheet-like, and may be electrically connected by overlapping them, or may be terminal shapes that can be fitted to each other so as not to be too thick. .
Here, if the insulating coating 2b of the lead wire 2 is a resin excellent in compatibility with the fluororesin layer A and the low thermal expansion resin layer, when the fluororesin layer A and the low thermal expansion resin layer are thermally fused, The fluororesin layer A and the low thermal expansion resin layer and the insulating coating 2b can be hermetically fused without generating a gap, and the object to be heated becomes the lead wire 2 and the fluororesin layer during use. It does not enter the planar heater through the gap between A and the low thermal expansion resin layer.

The structure of the planar heater of the present invention based on such a structure will be described with reference to FIG.
The conductive heating element 1 is provided with a terminal portion 1a to which a connection portion 2a of the lead wire 2 is connected. The low thermal expansion resin layer P is arranged on the upper side of the sheet-like heating element, the fluorine resin film A4a is further arranged on each of the upper and lower sides of the sheet-like heating element, and the fluorine resin film A4b is further provided on both sides of the fluorine resin film A4a. Two pieces of the heat diffusion material layer 5 carried on the substrate are respectively provided. Furthermore, it has a structure in which a fluororesin layer B6 is provided on the heat diffusion material layers on both sides.
Here, the fluororesin film A4b carrying the heat diffusion material layer 5 constitutes one fluororesin layer A together with the fluororesin film A4a.
Here, the fluororesin layers A and B used in the present invention are thermally fused to each other. As a result, the sheet heater of the present invention makes the heat generated by the conductive heating element uniform by the heat diffusion material layer. In addition, it can be used to heat non-heated materials.

In FIG. 6, a temperature sensor T is provided, and the temperature sensor T is installed between the fluororesin films 4a and 4b, and these films are fixed by being fused to each other.
The installation location of the temperature sensor T may be either one side or both sides of the planar heater, but usually one side.
The measurement result by the temperature sensor T is displayed on a device (not shown), calculated, or used as data for heating control.

The planar heater shown in FIG. 6 covers both sides with a fluororesin A for the conductive heating element 1, but another fluororesin member 7 for the terminal portion 1 a, the connection location 2 a, and the lead wire 2. It is covered with.
At this time, the other fluororesin member is thermally fused with the fluororesin layers A and / or B, and is also thermally fused with the insulating coating 2b of the lead wire 2, so that, for example, the surface of the present invention is in a liquid. Even when the cylindrical heater is immersed, the liquid does not enter the planar heater, so that the liquid can be stably heated without deterioration or reaction.
FIG. 7 shows a schematic view in the case where the conductive heating element 1 is covered using this other fluororesin member 7. At this time, the place where the conductive heating element 1 and the lead wire 2 are connected can be reliably covered with another fluororesin member 7, so even if an excessive force is applied to the planar heater when the planar heater is used. It is possible to prevent breakage or disconnection of the connected part.

(Manufacturing method of planar heater of the present invention)
The planar heater of the present invention is manufactured by sequentially stacking members constituting the planar heater and sequentially heat-sealing the fluororesin layer.
Specific production examples are as follows.
Prepare a sheet-like heating element in which the lead wire is connected to the terminal part connected to the conductive heating element, where the part where the lead wire is connected in advance to the terminal part is covered with a heat-sealing material if desired. The low thermal expansion resin layer P is arranged on the upper side, the lower side, or the upper and lower sides of the heating element, and the fluororesin layers A made of two fluororesin films are stacked on the upper and lower sides of the sheet-like heating element, respectively. Wear and integrate.
Thereafter, two heat diffusion material layers are respectively provided on the surfaces of the fluorine resin layers A on both sides, and a fluorine resin layer B is further provided on each of the heat diffusion material layers. In a state where the heat diffusion material layer is sandwiched, these layers are thermally fused and integrated.
At that time, the conductive heating element, the terminal portion, the connection location, and the lead wire can be combined and heat-sealed with the fluororesin layers A and B, or only the conductive heating element. In addition, the terminal portion and the like can be sealed with another fluororesin.
If a sheet heater having the fluororesin layer A as the uppermost layer without providing the heat diffusion material layer and the fluororesin layer B is used, the fluororesin layer inherently has a large thermal contraction rate. At the time of fusing, the fluororesin layer A shrinks and wrinkles and warpage are likely to occur, and the production yield also deteriorates. Also, if the thickness of the fluororesin layer A is reduced in order to improve the temperature rise characteristics of the planar heater, a heat spot is generated at a portion in contact with the conductive heating element, or the fluororesin layer A at the heat spot is thermally deteriorated. As a result, the product life of the planar heater may be shortened.

As a modification of the above production example, for two fluororesin films constituting only one fluororesin layer A out of the two fluororesin films constituting each of the two fluororesin layers A, Thus, a temperature sensor can be sandwiched between them.
Thereafter, the two fluororesin films are fused to form a fluororesin layer A, whereby the temperature sensor can be embedded in the fluororesin layer A.
Regardless of the provision of the temperature sensor, the fluororesin layers A and B may be integrated with a plurality of fluororesin film layers by fusion or the like.

(how to use)
The planar heater of the present invention can be used in place of a throw-in type heater such as a beaker, a liquid stirring container, and an oil bath. As a method of use in this case, for example, as shown in FIG. 8, the liquid L is put in the container Y, a planar heater is placed on the bottom of the container, immersed in the liquid, and stirred by the stirring device S. The sheet heater is heated to a predetermined temperature.
Of course, when it is used for the application described in the above-mentioned application section, it is not the method shown in FIG. Various objects to be heated can be heated by being buried in the solid or disposed below or above the solid such as a plate-like body.

As shown in FIG. 9, a planar heater (A) having the same configuration as the planar heater of the present invention except that a low thermal expansion resin layer is not disposed, and a low thermal expansion resin layer according to the present invention. The planar heaters (B) formed were prepared, and energization of these planar heaters was started with these planar heaters suspended in the air.
The thickness of each layer of the material constituting the planar heaters (A) and (B) is as shown in Table 1, and Table 2 shows the results of energizing these planar heaters.

導電性発熱体は、エッチングで導電路を形成したＳＵＳ箔（２０μm）を使用した。
フッ素樹脂層ＡとＢには、組成の異なるフッ素樹脂フィルムを使用し、低熱膨張性樹脂層にはポリイミドフィルム（５０μm）を使用した。
熱拡散材料層には銅箔（５０μｍ）を使用した。

As the conductive heating element, SUS foil (20 μm) in which a conductive path was formed by etching was used.
Fluororesin films having different compositions were used for the fluororesin layers A and B, and a polyimide film (50 μm) was used for the low thermal expansion resin layer.
Copper foil (50 μm) was used for the heat diffusion material layer.

According to the above results, in the planar heater (B) according to the present invention (that is, when there is a low thermal expansion resin layer), the fluororesin layer A melts at a high temperature (372 ° C.) after the start of energization. Even if it occurred, deformation of the conductive path of the conductive heating element did not occur, and no short circuit occurred.
On the other hand, in the planar heater (A) without the low thermal expansion resin layer, at 329 ° C., the conductive path of the conductive heating element due to the melting of the fluororesin was deformed and a short circuit occurred.
As can be seen from the above results, according to the present invention, the conductive heating element of the planar heater is not deformed during use, and it is short-circuited even when a higher voltage is applied or when it is used at a higher temperature. Without heating, the object to be heated can be heated.

DESCRIPTION OF SYMBOLS 1 ... Conductive heating element 2 ... Lead wire 3 ... Sheet-like heating element 4 ... Fluororesin layer A
5 ... Thermal diffusion material layer 6 ... Fluororesin layer B
7 ... Another fluororesin member T ... Temperature sensor Y ... Container L ... Liquid S ... Stirrer P ... Low thermal expansion resin layer

Claims (12)

A sheet-like heating element in which a lead wire is connected to a terminal portion connected to the conductive heating element;
Low heat coefficient of thermal expansion of 8 × 10 ⁻⁵ / ° C. or less on the entire surface of at least one side of the conductive heating element or the entire surface of at least one side of the sheet-like heating element including the conductive heating element and the terminal portion. Providing an expandable resin layer;
It is sandwiched and heat-sealed by the fluororesin layer A that can be heat-sealed from both sides,
Furthermore, on each surface of the fluororesin layer A capable of being thermally fused on both sides, a thermal diffusion material layer made of a sheet or foil selected from graphite and a resin containing a large amount of an inorganic substance is provided.
Another fluororesin layer B that can be heat-sealed is further provided on the surface of the heat diffusion material layer.
Surface heater.   The planar heater according to claim 1, wherein the low thermal expansion resin layer contains a resin having a melting point of 200 ° C or higher.   The planar heater according to claim 1 or 2, wherein the low thermal expansion resin layer is a layer containing at least one of a polyamide resin, a polyimide resin, a polyether ether ketone resin, and a polyphenylene sulfide resin.   At least one of the two fluororesin layers A that can be heat-sealed to each other and / or at least one of the heat-sealable fluororesin layers B provided on the respective surfaces of the heat diffusion material layer, The planar heater according to any one of claims 1 to 3, which is a layer formed by laminating a plurality of heat-sealable fluororesin films and heat-sealing them.   The planar heater according to any one of claims 1 to 4, wherein a portion where a lead wire is connected to a terminal portion connected to the conductive heating element is previously covered with a heat-sealing material.   The planar heater according to any one of claims 1 to 5, wherein the sheet-like heating element and the end face of the heat diffusion material layer are sealed with the fluororesin layers A and B.   The fluororesin layers A and B may be made of the same material or different materials, and are made of FEP (tetrafluoroethylene / hexafluoropropylene copolymer) and / or PFA (perfluoroalkoxy fluororesin). Item 7. The sheet heater according to any one of Items 1 to 6.   The planar heater according to any one of claims 1 to 7, having a structure in which both sides and the entire circumference of the heat diffusion material layer are covered with the fluororesin layers A and B.   The planar heater according to any one of claims 1 to 8, wherein the thicknesses of the fluororesin layers A and B are independently 0.025 to 3.0 mm.   One or more temperature sensors are embedded between one or more of the low thermal expansion resin layer and the fluororesin layers A and B, and between the low thermal expansion resin layer and the fluororesin layer A. The planar heater according to any one of 9.   One or more temperature sensors are provided between any of the plurality of layers constituting the low thermal expansion resin layer and the plurality of heat-sealable fluororesin films constituting the fluororesin layers A and B. Item 11. The planar heater according to Item 10. Where necessary, the sheet heating element in which the lead wire is connected to the terminal portion connected to the conductive heating element, the portion where the lead wire is connected to the terminal portion in advance is covered with the heat fusion material in advance.
Low heat coefficient of thermal expansion of 8 × 10 ⁻⁵ / ° C. or less on the entire surface of at least one side of the conductive heating element or the entire surface of at least one side of the sheet-like heating element including the conductive heating element and the terminal portion. Providing an expandable resin layer;
It is sandwiched and heat-sealed by a fluororesin layer A that can be heat-sealed from both sides,
Furthermore, on each surface of the fluororesin layer A capable of being thermally fused on both sides, a thermal diffusion material layer made of a sheet or foil selected from graphite and a resin containing a large amount of an inorganic substance is provided.
A step of providing another fluororesin layer B that can be thermally fused on the surface of the heat diffusion material layer;
Manufacturing method of planar heater.

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