JP2017147085A - Planar heating element and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a planar heating element which is equipped with sufficient flexibility without spoiling original air permeability of fabric and can design a pattern shape of an electrode part and a heating part with a high degree of freedom, and also to provide a method of manufacturing the same.SOLUTION: Disclosed is a planar heating element which, on one surface of fabric 1, has two or more pattern-like electrodes 2 made of a metal film of thickness 0.1 to 10 μm and independent from each other, and a heating film 3 connecting between two or more pattern-like electrodes and whose average air permeability is 3 to 50 cm/(cms). The heating film may be formed of a conductive particulate and a resin component. The planar heating element may have a protective film for covering portions in which the pattern-like electrodes and the heating film are formed.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a planar heating element having two or more patterned electrodes formed by plating on one surface of a fabric, and a heating film formed straddling the two or more patterned electrodes, and a method for manufacturing the same. About. Specifically, the present invention relates to a planar heating element having air permeability and sufficient flexibility and a method for manufacturing the same.

  Conventionally, as a planar heating element having flexibility, a metal film (cathode, anode) on a polymer film, and a resin film having a relatively high electrical resistance containing carbon particles or the like between the cathode and anode, A heating element in which is formed has been used. However, when a conventional sheet heating element is used in a place where it comes into contact with the human body, such as clothes, chairs, and vehicle seats, the use of a polymer film as the substrate causes problems such as stuffiness and hardness. Become.

  As a method for solving the problem of stuffiness and hardness of the planar heating element, it has been proposed to use a fabric for the base material. For example, Patent Document 1 discloses a planar heating element in which an electrode part and a heating part are formed by printing and drying an ink conductive material and a resistor material on the surface of a substrate. Patent Document 2 proposes a planar heating element including a heat generating part formed of a fiber structure including conductive fibers and a conductive agent and a binder component as an electrode part for energizing the heat generating part. Further, in Patent Document 3, a metal wire is sewn as an electrode in a conductive sheet in which a resin containing conductive powder is carried on a nonwoven fabric, and the conductive sheet and the electrode are sandwiched between insulating sheets. An open sheet heating element is disclosed.

  However, the method of printing and drying the conductive material and resistor material in the ink state may result in insufficient conductivity, and the fabric is hard, heavy and thick because it is necessary to increase the amount of ink to be printed in order to increase the conductivity. Tend to be. As a result, there was a risk that the fabric could not follow the flexibility and cracked. In addition, in the portion where the ink is applied, the air permeability of the fabric is significantly reduced. On the other hand, there is a problem that the degree of freedom of the pattern shape is low in the method of knitting or sewing using conductive fibers or metal wires.

JP 2008-269914 A JP2013-191551A JP 2007-184230 A

  The present invention provides a planar heating element and a method for manufacturing the same that have sufficient flexibility without impairing the inherent breathability of the fabric and that can be designed with a high degree of freedom in the pattern shape of the electrode part and the heating part. This is the issue.

  As a result of intensive studies, the present inventors have found that a planar heating element having a patterned electrode formed by plating on a fabric and having a heating film formed so as to connect the patterned electrodes is It has been found that the problems can be solved, and the present invention has been completed.

That is, according to the present invention, two or more independent patterned electrodes made of a metal film having a thickness of 0.1 to 10 μm and a heat generating film connecting the two or more patterned electrodes are formed on one surface of the fabric. It is a planar heating element having an average air permeability of ³ to 50 cm ³ / (cm ² · s).

  The heat generating film is preferably formed of conductive fine particles and a resin component. You may have the protective film which coat | covers the part in which the said pattern electrode and the heat generating film were formed.

The present invention also includes a step of printing on one surface of the fabric in two or more independent pattern shapes using an ink containing an electroless plating catalyst, and electroless after activating the electroless plating catalyst. A step of forming two or more independent patterned electrodes by performing a plating treatment to form a metal film having a film thickness of 0.1 to 10 μm on the patterned portion and connecting the two or more patterned electrodes. And forming a heat generating film by printing with ink containing conductive fine particles, and the average air permeability after forming the heat generating film is ³ to 50 cm ³ / (cm ² · s) This is a method for producing a planar heating element.

  Furthermore, a step of forming a protective film so as to cover a portion where the patterned electrode and the heat generating film are formed may be included.

  The planar heating element of the present invention retains the air permeability of the fabric despite having the patterned electrode and the heating film. In the planar heating element of the present invention, the patterned electrode is made of a metal film having a film thickness of 0.1 to 10 μm and is formed while retaining the internal voids of the fabric. It has sufficient conductivity and is excellent in followability to a shape change such as bending and flexibility.

It is a top view which shows an example of the planar heating element of this invention. It is a top view which shows another example of the planar heating element of this invention.

  The planar heating element of the present invention uses a fabric made of fibers as a base material. The types of fibers that make up the fabric include synthetic fibers (polyamide, polyester, polyurethane, polyacryl, etc.), semi-synthetic fibers (acetate, triacetate, etc.), recycled fibers (rayon, cupra, etc.), natural fibers (cotton, hemp, wool) Synthetic fibers are preferred from the viewpoints of strength and chemical resistance. Particularly preferred synthetic fibers include polyamide and polyester.

  The form of the fiber used in the present invention may be a monofilament yarn, a multifilament yarn, a spun yarn, a covering yarn, or the like. The thickness of the yarn is not particularly limited, but is preferably 10 to 70 dtex in the case of a monofilament, and preferably 10 to 170 dtex in the case of a multifilament.

  Specific examples of the fabric include fiber fabrics such as woven fabrics, knitted fabrics, and non-woven fabrics, and there is no particular limitation on the structure and constituent fibers.

The fabric may be subjected to dyeing, antistatic processing, flame retardant processing, calendar processing, and the like as necessary. The breathability of the fabric itself as the base material is preferably about ³ to 100 cm ³ / (cm ² · s).

  The patterned electrode formed on the fabric in the present invention is made of a metal film having a thickness of 0.1 to 10 μm. When the film thickness is 0.1 to 10 μm, the patterned electrode can be formed without losing the air permeability of the fabric itself. Further, if the film thickness is within this range, a sufficiently low resistance value for functioning as an electrode can be obtained.

  The patterned electrode needs at least two or more electrodes to be a cathode and an anode, respectively. Two or more patterned electrodes are formed independently and do not short-circuit. It is desirable that the patterned electrode is formed not only on the surface of the fabric but also on the inside in the thickness direction of the fabric. However, even in this case, it is important that the voids of the fabric are not completely blocked. The formation range of the patterned electrode formed up to the inside in the thickness direction of the fabric is preferably 10 to 80% with respect to the thickness of the fabric.

  The pattern shape of the pattern electrode is not particularly limited. In order to form an electrode having a free pattern shape, as described in the method for producing a planar heating element described later, printing using an ink containing an electroless plating catalyst, followed by a method by an electroless plating method Is the best.

  Examples of the metal constituting the patterned electrode include at least one metal selected from the group consisting of copper, nickel, tin, and silver, or an alloy thereof (for example, an alloy of copper and tin). Copper and nickel are preferable, and copper is particularly preferable.

  The heating film in the planar heating element of the present invention is preferably one in which conductive fine particles are dispersed in a resin component. Examples of the conductive fine particles include carbon black, graphite, and metal particles. Carbon black is particularly preferable from the viewpoint of excellent durability and corrosion resistance. The particle size of the conductive fine particles of carbon black is preferably 10 to 300 nm, and more preferably 30 to 150 nm. Examples of the shape of the conductive fine particles include flakes, particles, and fibers. From the viewpoint of entering into the inter-fiber gaps of the fabric structure of the fabric and the patterned electrode, and improving the adhesion to the fabric and the contact with the electrode, it is preferably particulate.

  Examples of the resin component constituting the heat generating film include acrylic resin, melamine resin, epoxy resin, urethane resin, polyester resin, polyurethane resin, polyamine resin, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, and the like. . Of these, polyurethane resin, epoxy resin, and ethylene-vinyl acetate copolymer are particularly preferable.

  As content of the electroconductive fine particles in a heat generating film, it is preferable that it is 70-95 mass% with respect to the mass of a heat generating film. When the content of the conductive fine particles is in the range of 70 to 95% by mass, both the flexibility of the planar heating element and the highly efficient heat generation performance can be achieved.

  The thickness of the heat generating film is preferably 1 to 50 μm. When the thickness of the heat generating film is 1 to 50 μm, it is possible to achieve both the flexibility of the planar heat generating element and the highly efficient heat generating performance.

The planar heating element of the present invention has an average air permeability of ³ to 50 cm ³ / (cm ² · s). The average value of the air permeability over the entire surface heating element is defined as the average air permeability. The pattern electrode and the heat generating film are arranged in an arbitrary shape, and the air permeability varies depending on the location to be measured. The factor is the area ratio of the patterned electrode and the heat generating film on the fabric. Therefore, the average air permeability is calculated by the following calculation formula from the area ratio (%) between the electrode and the heat generating film in the total area of the sheet heating element and the air permeability of the fabric itself.

  The heat generating film can have any shape as long as it satisfies the requirement of connecting two or more patterned electrodes. It is necessary to devise the shape and size of the heat generating film according to the application and required performance, and to ensure the average air permeability as the entire sheet heating element. At that time, it is desirable to design the planar heating element in consideration of the air permeability of the fabric itself.

  In the planar heating element of the present invention, the two or more patterned electrodes and the planar heating element may be covered with a protective film made of a resin composition. The protective film preferably covers only a portion where the two or more patterned electrodes and the planar heating element are formed. In other words, it is preferable that the portion where the patterned electrode and the planar heating element are not formed, that is, the portion where the fabric as the substrate is exposed is not covered with the protective film. With such a configuration, the air permeability of the fabric can be maintained to the maximum.

  Examples of the resin composition constituting the protective film include those mainly composed of polyurethane resin, silicone resin, acrylic resin and the like. In particular, polyurethane resin and silicone resin are preferable from the viewpoint of high flexibility. The thickness of the protective film is preferably 7 to 30 μm. If the thickness of the protective film is 7 to 30 μm, the flexibility, insulation and water resistance of the planar heating element are satisfied. The resin composition constituting the protective film may contain various additives as necessary in addition to the main component. Examples of additives include water repellents, flame retardants, plasticizers, antifungal agents, deodorants, and antibacterial agents.

  Next, the manufacturing method of the planar heating element of this invention is demonstrated. In the manufacturing method of the planar heating element of the present invention, the first step includes a step of printing in two or more independent pattern shapes using an ink containing an electroless plating catalyst on one side of the fabric. .

  Examples of the ink containing an electroless plating catalyst include a solution containing a metal ion that can be reduced to become a metal having electroless plating catalytic activity. Examples of the metal having electroless plating catalytic activity include copper, nickel, silver, tin, rhodium, palladium, gold and platinum, but it is preferable to use palladium having a high plating catalytic activity. Examples of the compound that generates palladium ions as the metal ions include palladium chloride, palladium bromide, palladium acetate, palladium sulfate, palladium nitrate, palladium acetylacetonate, and palladium oxide. Among these, palladium chloride, which is widely used as a general catalyst, is preferably used because it is relatively easy to obtain.

  The ink containing an electroless plating catalyst contains at least a polyfunctional compound and a solvent in addition to the metal ions. The polyfunctional compound is compounded for the purpose of improving the adhesion between metal ions and fibers, and is a compound composed of two or more functional groups including a functional group that adsorbs metal ions and a functional group that adsorbs to fibers. Examples of functional groups that adsorb metal ions include amino groups and carboxyl groups, and examples of functional groups that adsorb to fibers include amino groups, carboxyl groups, and hydroxyl groups. Examples of the polyfunctional compound include amino acids such as glutamic acid, glycine, and arginine as compounds having an amino group and a carboxyl group. Examples of the compound having two or more amino groups include diamines such as ethylenediamine and propylenediamine. Examples of the compound having an amino group and a hydroxyl group include amino alcohols such as 2-aminoethanol and 1-amino-2-propanol. Examples of the solvent include water and alcohol. In addition, a thickening component, a pigment, inorganic fine particles (filler), a leveling agent, a dispersion stabilizer, an antifoaming agent, and the like may be appropriately included depending on the type of printing.

  Examples of the method of printing two or more independent pattern shapes on one surface of the fabric using the ink containing the electroless plating catalyst include ink jet printing, screen printing, gravure printing, dispensing, and the like. Of these, inkjet printing is preferred because it does not contain a large amount of solids other than metal ions and can sufficiently exhibit the catalytic activity of metal ions. It is preferable to appropriately perform a drying process after printing. As drying conditions, for example, the temperature is 60 to 120 ° C., and the time is 1 to 10 minutes.

  When employing ink jet printing, the viscosity of the ink is preferably 1 mPa · s to 20 mPa · s. If the viscosity of the ink is within this range, the effect that ink bleeding can be minimized and a sufficient amount of the plating catalyst can be applied can be obtained.

  The two or more pattern shapes formed in the above process become two or more pattern electrodes formed in the process described later, and correspond to at least the cathode and the anode.

  In the manufacturing method of the planar heating element of the present invention, as the next step, the electroless plating catalyst is activated and then electroless plating treatment is performed to form a metal film having a film thickness of 0.1 to 10 μm on the pattern shape portion. This includes a step of forming two or more independent patterned electrodes.

  As a process for activating the electroless plating catalyst contained in the ink printed in a pattern on the fabric surface, a reduction process using a reducing agent is applied. Examples of the reducing agent include dimethylamine borane, sodium hypophosphite, hydrazine, diethylamine, ascorbic acid, borohydrofluoric acid (tetrafluoroboric acid), and the like. The reduction treatment is performed by immersing the fabric in a reduction treatment solution in which these reducing agents are dissolved in water, and bringing the electroless plating catalyst contained in the ink printed on the surface of the fabric into contact with the reducing agent.

  In addition to the reducing agent, the reducing treatment liquid may contain a pH adjusting agent, a pH buffering agent, and the like.

  The time for the reduction treatment is 10 to 300 seconds, preferably 30 to 180 seconds. The temperature of the reduction treatment liquid is preferably 20 to 60 ° C, and more preferably 30 to 50 ° C. After contact with the reducing treatment solution, the fabric is washed with water to remove the non-specifically attached reducing agent. After the reduction treatment, the electroless plating catalyst printed on the fabric is activated by washing and drying as necessary.

  After the electroless plating catalyst is activated, an electroless plating process is performed, and a metal film is formed on a portion to which ink containing the electroless plating catalyst printed in a pattern shape is applied. Examples of the metal forming the metal coating include at least one metal selected from the group consisting of copper, nickel, tin, and silver, or an alloy thereof (for example, an alloy of copper and tin). Copper and nickel are preferable, and copper is particularly preferable.

  As a method for the electroless plating treatment, a known electroless plating method can be used. An existing plating bath can be used for electroless plating, and the fabric may be immersed in this plating bath. Although the reaction time and temperature of electroless plating can be suitably adjusted according to the plating film thickness, the preferable plating time is 5 to 20 minutes, and the preferable temperature is 40 to 50 ° C. The film thickness of the metal coating (conductive pattern) thus obtained is preferably 0.1 to 10 μm, more preferably 1 to 5 μm.

  After the formation of the metal coating by the electroless plating treatment, the cloth can be washed with water as necessary to remove the non-specifically deposited plating solution.

  In the method for manufacturing a planar heating element of the present invention, as a next step, a step of forming a heating film by printing ink containing conductive fine particles and a resin component so as to connect the two or more patterned electrodes is connected. including.

  Examples of the conductive fine particles include carbon fine particles and metal fine particles. More specifically, carbon black, graphite, gold powder, silver powder, copper powder, nickel powder, aluminum powder, plating powder, and the like.

  The resin component contained in the ink is essential for dispersing the conductive fine particles and fixing them on the fabric. Examples of such resin components include polyurethane resins, epoxy resins, acrylic resins, and the like, and polyurethane resins, epoxy resins, and ethylene-vinyl acetate copolymers are preferable from the viewpoint of flexibility. In addition, the ink may contain a leveling agent, a dispersion stabilizer, an antifoaming agent, and the like.

  The content of the conductive fine particles in the ink is preferably 70 to 95% by mass, and particularly preferably 80 to 95% by mass with respect to the mass of the heat generating film. If content of electroconductive fine particles is 70-95 mass%, the effect of coexistence with the softness | flexibility of a heat generating film and highly efficient heat generating performance will be acquired.

  The content of the resin component in the ink is preferably 5 to 30% by mass with respect to the mass of the heat generating film.

  The manufacturing method of the planar heating element of the present invention may additionally include a step of forming a protective film made of a resin composition so as to cover only a portion where the patterned electrode and the heating film are formed. it can.

  Examples of the resin composition forming the protective film include polyurethane resins, silicone resins, acrylic resins, and among them, polyurethane resins are preferable from the viewpoint of flexibility. The resin composition preferably exhibits water resistance when a protective film is formed. The resin composition forming the protective film may contain a leveling agent, a dispersion stabilizer, an antifoaming agent, and the like.

  The method for forming the protective film is not particularly limited, but it is preferable to use a printing method or an electrodeposition coating method. In the electrodeposition coating method, the resin film can be applied only to the conductive portion by immersing the fabric in a resin solution for electrodeposition coating and energizing the conductive pattern in this state. By using the electrodeposition coating method, it becomes possible to form a very thin and uniform resin film only on the pattern electrode and the heat generating film, and the gap in the fabric can be kept sufficiently by adjusting the film thickness. it can.

  Examples of the resin liquid used for electrodeposition coating include acrylic resin, melamine resin, epoxy resin, urethane resin, polyester resin, and polyamine resin. The electrodeposition coating treatment temperature is preferably 20 to 30 ° C., the voltage is preferably 10 to 150 V, the conduction time is preferably 30 to 180 seconds, and the distance between the electrodes is 50 to 200 mm.

  The protective film thus formed has a thickness of 7 to 30 μm, more preferably 7 to 20 μm, and particularly preferably 10 to 15 μm. If the film thickness is in the range of 7 to 30 μm, there is no possibility that the insulation is insufficient due to being too thin, or the texture of the fabric becomes hard due to being too thick.

The planar heating element according to the present invention has an air permeability according to JIS L1096 “General Textile Testing Method” of the breathability A method (Fragile method) as ³ to 50 cm ³ / (average breathability over the entire surface heating element. cm ² · s). If the average air permeability is within this range, stuffiness is unlikely to occur even when used in contact with the human body, such as clothes.

Examples The present invention will be described below with reference to examples, but the present invention is not limited to these examples.
The evaluation methods for various physical properties in this example are as follows.

<Exothermic>
The temperature distribution of the exothermic film 5 minutes after the current was applied was measured by infrared thermography (Flier Systems, model number FLIR C2). The temperature distribution was measured over a length of 50 mm of the heat generating film. If the difference between the lowest temperature and the highest temperature in this measurement range was within 2 ° C, it was marked as ◯. Moreover, it was set as x also when the abnormal heat_generation | fever of an electrode generate | occur | produced.

<Breathability>
The air permeability of the fabric itself was measured in accordance with JIS L1096 8.26.1A “Fragile shape method”. The air permeability of the planar heating element is zero from the portion where the electrode, the heat generating film and the protective film are formed, and the ratio of the portion where the electrode and the heat generating film are not formed and the value of the air permeability of the fabric itself. The average air permeability of the planar heating element was calculated by the above equation (Equation 1). If the average air permeability of this planar heating element is in the range of ³ to 50 cm ³ / (cm ² · s), it is indicated as “◯”, and if out of the range, it is indicated as “x”.

<Flexibility>
The hardness when the planar heating element was bent was evaluated by a sensory test. The case where the flexibility was judged to be significantly impaired as compared with the case of a single fabric was evaluated as x, and the others were evaluated as ◯. In addition, the case where any of the electrode, the heat generating film, and the protective film was broken due to the bending was marked as x.

[Example 1]
(1) As a patterned electrode forming fabric, the weft density of warp yarn made of polyethylene terephthalate fiber (56 dtex / 72f) is 159 / inch, the weft density of weft is 120 / inch, and the air permeability is 38 cm ³ / (cm ² · s. ) Polyester plain fabric. A pair of electrode patterns was formed by applying ink containing an electroless plating catalyst to the fabric so as to have a width of 5 mm and a length of 100 mm by inkjet printing. The distance between the electrodes at this time was set to 100 mm. The electroless plating catalyst ink used here was 3% by mass of palladium chloride as the electroless plating catalyst metal ion, 1% by mass of 2-aminoethanol as the polyfunctional compound, 80% by mass of octanol as the solvent, and 16% of water. % Contained. Subsequently, the palladium salt on the fabric was reduced by immersing in an acidic treatment solution containing a reducing agent (pH 6.0; 0.1 M citrate buffer; 20 mM dimethylamine borane) at 40 ° C. for 180 seconds. Subsequently, electroless copper plating treatment was performed at 50 ° C. for 60 minutes. For the electroless copper plating, copper chloride dihydrate 5 g / L, EDTA · 2Na 20 g / L, and sodium hydroxide 7.5 g / L were used. By the above process, a fabric having a patterned electrode having a metal (copper) film thickness of 3 μm was obtained.

(2) Heat generation film formation Next, a high resistance ink (manufactured by Future Carbon Co., Ltd.) formed by dispersing carbon particles and polyurethane resin in an aqueous solvent so as to connect the pattern electrode on the fabric having the pattern electrode. Carbo e-Therm) was coated by screen printing as shown in FIG. 1 by providing a non-coated portion having a circular shape with a diameter of 15 mm. Subsequently, drying was performed at 100 ° C. for 30 minutes to form a heating film having a thickness of 30 μm.

Subsequently, a polyurethane resin was applied only on the heat generating film by screen printing to form a protective film. The polyurethane resin used here is 97% by mass of the trade name “Superflex E-4800” manufactured by Daiichi Kogyo Seiyaku Co., Ltd., and the product name “DK thickener SCT-275” of Daiichi Kogyo Seiyaku Co., Ltd. as a thickener. It contains 3% by mass. Subsequently, drying was performed at 100 ° C. for 10 minutes to form a protective film having a thickness of 20 μm. This protective film has a water resistance of 5% or less and a change in area of 1% or less after being immersed in warm water of 40 ° C. for 24 hours. Further, the surface resistance value of the protective film is 10 ¹³ Ω / □ or more (measuring device: “Hiresta UP” manufactured by Mitsubishi Chemical Analytech Co., Ltd.) and has an insulating property. In the portion where the heat generating film was not printed, the original air permeability of the fabric was maintained.

Thereby, the planar heating element in the present invention was obtained. When an AC voltage of 5 V was applied to the two electrode portions with respect to the obtained heating element, no abnormal heat generation was observed at the electrode portions, and the lowest surface temperature was 59.2 ° C. and the highest temperature was 60.degree. A uniform temperature distribution of 1 ° C. and a temperature difference of 0.9 ° C. was confirmed. The coverage of the obtained planar heating element with the electrode, heating film and protective film was 75%, and the breathability of the planar heating element calculated from the non-covering ratio and the breathability of the fabric used was 9.5 cm ^3. / (Cm ² · s), and had moderate air permeability. Further, even when bent, none of the electrode, the heat generating film, and the protective film was torn, and the flexibility was maintained.

[Example 2]
The same operation as in Example 1 was performed except that the electrode pattern and the heating film were formed as shown in FIG. The electrode is branched from an electrode having a width of 5 mm and a length of 350 mm every 80 mm, and an electrode having a width of 5 mm and a length of 70 mm is branched, and the distance between the other electrode of the pair and the branch electrode is 50 mm. A heating film was formed on this electrode pattern, and a planar heating element having 50 mm × 50 mm heating portions arranged in parallel was obtained. When an AC voltage of 5 V was applied to the two electrode portions in the same manner as in Example 1 for the obtained heating element, no abnormal heat generation was observed at the electrode portions, and the minimum surface temperature was 39.6 ° C. A uniform temperature distribution with a maximum temperature of 40.8 ° C. and a temperature difference of 1.2 ° C. was confirmed. The coverage of the obtained planar heating element by the electrode, the heating film and the protective film was 40%, and the breathability of the planar heating element calculated from the non-coverage ratio and the breathability of the fabric used was 22.8 cm ^3. / (Cm ² · s). Even if bent, none of the electrode, the heat generating film, and the protective film was torn, and the flexibility was maintained.

[Comparative Example 1]
The electrode formation was performed in the same manner as in Example 1 except that the conductive silver paste was used. To form an electrode, a conductive silver paste “FS RA007” manufactured by Toyo Ink Co., Ltd. was used. After pattern formation by screen printing, an electrode having a thickness of 10 μm was formed at 130 ° C. for 30 minutes. When an AC voltage of 5 V was applied to the two electrode portions in the same manner as in Example 1 with respect to the obtained heating element, abnormal heat generation at the electrode portions was observed. In addition, the electrode was torn due to bending.

[Comparative Example 2]
It carried out similarly to the comparative example 1 except having made the film thickness of the electroconductive silver paste into 40 micrometers. When an AC voltage of 5 V was applied to the two electrode portions in the same manner as in Example 1 for the obtained heating element, abnormal heat generation at the electrode portions was not observed, and the minimum surface temperature was 58.0 ° C. A uniform temperature distribution with a maximum temperature of 59.6 ° C. and a temperature difference of 1.6 ° C. was confirmed. Although no electrode breakage due to bending was observed, the obtained planar heating element had a hard electrode portion and lost flexibility.

[Comparative Example 3]
The same operation as in Comparative Example 1 was performed except that a protective film was formed on the entire surface. The obtained heat generating body had zero air permeability (unmeasurable), and the original air permeability of the fabric was lost. When an AC voltage of 5 V was applied to the two electrode portions, abnormal heat generation at the electrode portions was observed.

  The planar heating element of the present invention has sufficient exothermicity and excellent flexibility without impairing the inherent moisture permeability and breathability of the fabric. Such a planar heating element of the present invention can be suitably used for clothing, industrial materials, medical / welfare tools, and the like.

1: Fabric 2: Patterned electrode 3: Heat generation film

Claims (5)

One surface of the fabric has two or more independent patterned electrodes made of a metal film with a thickness of 0.1 to 10 μm and a heat generating film connecting the two or more patterned electrodes, and has an average air permeability. Is a sheet heating element having a thickness of ³ to 50 cm ³ / (cm ² · s).   The planar heating element according to claim 1, wherein the heating film is formed of conductive fine particles and a resin component.   The planar heating element of Claim 1 which has a protective film which coat | covers the part in which the said pattern electrode and the heating film were formed. Printing on two or more independent pattern shapes on one surface of the fabric using an ink containing an electroless plating catalyst;
Activating the electroless plating catalyst and performing an electroless plating process to form a metal film having a film thickness of 0.1 to 10 μm on the pattern-shaped portion to form two or more independent patterned electrodes; ,
Forming an exothermic film by printing ink containing conductive fine particles so as to connect between the two or more patterned electrodes,
The method for producing a planar heating element, wherein an average air permeability after forming the heating film is ³ to 50 cm ³ / (cm ² · s).   The manufacturing method of the planar heating element of Claim 4 including the process of forming a protective film so that the part in which the said pattern electrode and the said heat generating film were formed may be coat | covered.