JP2009117199A - Surface heating body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface heating body which is flexible in a multilayered structure and can improve seating feeling when using it as a seat heater for a vehicle. <P>SOLUTION: The surface heating body 1 includes a resin composition and a conductor, the conductor is formed by various kinds of carbon blacks and graphite in which average particle sizes are spread out at three times or more. The surface heating body 1 is excellent on the seating feeling since its structure is simple and it is made of a flexible material, and is excellent on productivity. Furthermore, it is also excellent on low resistivity and a PTC characteristic. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a polymer resistor composition having excellent PTC characteristics and a deformable surface having flexibility and high reliability that can be attached to an instrument having an arbitrary surface shape using the polymer resistor composition. Related to a heating element.

  Conventionally, in this type of planar heating element, a heating element is used that is manufactured by printing, drying, and firing a resistor ink in which a base polymer and a conductive material are dispersed in a solvent. For example, refer to Patent Document 1, Patent Document 2, and Patent Document 3.)

  This resistor generates heat when energized. For this type of resistor, generally, carbon black, metal powder, or the like is used as a conductive substance, and a crystalline resin is used as a base polymer. With such a material, the heat generating portion exhibits PTC characteristics.

  5 and 6 show the prior art described in the above-mentioned Patent Document 1. A sheet heating element 30 includes a base material 31, a pair of comb-shaped electrodes 32 and 33, a polymer resistor 34, and a covering. Material 35. The electrically insulating substrate 31 is made of a resin such as a polyester film.

  The comb-shaped electrodes 32 and 33 are formed on a base material 31 by printing and drying a conductive paste such as a silver paste.

  The polymer resistor 34 is formed by printing and drying polymer resistor ink at a position where power is supplied by the comb-shaped electrodes 32 and 33.

  The covering material 35 made of the same material as the base material 31 covers and protects the comb-shaped electrodes 32 and 33 and the polymer resistor 34.

  When using a polyester film as the base material 31 and the covering material 35, a heat-fusible resin 36 such as a modified polyethylene is bonded to the covering material 35 in advance.

  Then, pressurizing while applying heat. By doing in this way, the base material 31 and the coating | covering material 35 are joined via the heat-fusible resin 36. FIG.

  The covering material 35 and the heat-fusible resin 36 isolate the comb-shaped electrodes 32 and 33 and the polymer resistor 34 from the outside. Therefore, long-term reliability is imparted to the planar heating element 30.

  FIG. 7 shows an apparatus for laminating the covering material 34. As a heating and pressurizing method, a laminator 39 composed of two heating rolls 37 and 38 is generally used. That is, the base material 31 in which the comb electrodes 32 and 33 and the polymer resistor 34 are formed in advance and the coating material 35 in which the heat-fusible resin 36 is bonded in advance are supplied, and these are heated by the heating rolls 37 and 38. Heat and pressurize. In this way, the planar heating element 30 is produced.

  The PTC characteristic means a resistance temperature characteristic in which the resistance value increases as the temperature rises, and the resistance value increases rapidly when a certain temperature is reached. The polymer resistor 34 having PTC characteristics can give the planar heating element 30 a self-temperature adjusting function.

Patent Document 2 discloses that a PTC composition composed of amorphous polymer, crystalline polymer particles, carbon black, and an inorganic filler is dispersed in an organic solvent to prepare an ink, and then PTC is formed on a resin film provided with electrodes. A planar heating element is described in which a polymer resistor is printed with a composition ink, subjected to heat treatment for crosslinking, and a resin film is laminated as a protective layer of the polymer resistor.

  The planar heating element of Patent Document 2 has a heat generating function similar to that of Patent Document 1.

  As the resin exhibiting the PTC characteristics of the polymer resistor 44, a modified olefin resin which is a low melting point resin, such as ethylene vinyl acetate copolymer, ethylene ethyl acrylate copolymer, ethylene methyl methacrylate copolymer, ethylene An ester-based ethylene copolymer such as a methacrylic acid copolymer or ethylene butyl acrylate is used, and the polymer resistor 44 is cross-linked by a method such as a cross-linking material or ultraviolet irradiation in order to suppress a change due to a change in resistance value with time. It is common.

Here, the resistance change magnification (R50 / R20), which is the ratio between the resistance value of 50 ° C. and the resistance value of 20 ° C. of the polymer resistor 44, is less than 2.
Japanese Patent Laid-Open No. 56-13689 JP-A-8-120182

  The conventional planar heating element 30 uses a rigid material such as a polyester film as the base material 31. The substrate 31 has a five-layer structure including a comb-shaped electrode 32, 33 printed thereon, a polymer resistor 34, and a covering 35 having an adhesive layer disposed thereon. .

  Therefore, depending on the material and the thickness of the base material 31 and the covering material 35, flexibility is lacking. That is, when the planar heating element 30 is used as a car seat heater (heater for heating a seat of an automobile), the seating feeling is impaired, and when it is used as a handle heater, the feeling of touch is impaired.

  Moreover, since the shape is planar, when a load due to seating or the like is applied to a part of the surface, the force is exerted on the entire surface and the planar heating element 30 is deformed.

  Depending on the shape of the deformation, the closer to the end of the sheet heating element 30, the larger the amount of deformation, causing creases or the like in part of the surface. There is a possibility that cracks or the like may occur in the comb-shaped electrodes 32 and 33 and the polymer resistor 34 in the folded portion. Therefore, durability may be reduced.

  Further, since the base material 31 such as a non-breathable polyester sheet and the covering material 35 are used, moisture is likely to be trapped when used for a car seat heater or a handle heater. Therefore, when used for a long time, the seating feeling and the touch feeling are impaired.

  The present invention solves the above-described conventional problems, and provides a planar heating element that easily exhibits flexibility even when an external force is applied, improves a seating feeling and a feeling of touch, and has an improved magnification. With the goal.

  In order to solve the above-described conventional problems, the planar heating element of the present invention includes a resin composition in which a main component is cross-linked through a reactive resin, a conductor composed of a plurality of types of carbon black and graphite, and electrical insulation. And a polymer resistor characterized in that the plurality of types of carbon black and graphite have different average particle diameters.

  Thereby, a high change magnification can be realized. Moreover, since the resin composition is bridge | crosslinked, the resistor composition can suppress the time-dependent change of a specific resistance value. Thereby, stable PTC characteristics over a long period, that is, stable heat generation performance can be realized.

  The planar heating element of the present invention is composed of a polymer resistor having high PTC characteristics, so that it has excellent performance as a heating element and high workability, so that productivity can be improved. Cost polymer resistors can be produced.

  A first invention includes a resin composition in which a main component is cross-linked through a reactive resin, a conductor composed of a plurality of types of carbon black and graphite, and an electrically insulating substrate, and the plurality of types of carbon black And a polymer resistor characterized in that the average particle diameters of graphite and graphite are different.

  By using carbon black and graphite having different particle diameters, or carbon black and graphite having different particle diameters, or carbon black having different particle diameters and graphite having different particle diameters as a conductor, the change ratio can be set to 2 or more. Can be high.

  In addition, since the resin composition is cross-linked, it is possible to suppress the time-dependent change of the specific resistance value and to obtain stable PTC characteristics over a long period of time. In other words, it is possible to realize a stable heat generation performance by preventing a decrease or rise in a preset heat generation temperature.

  In the second invention, the ratio of the average particle diameter of the two types of carbon black is 3 times or more. When the average particle diameter ratio of carbon black is less than 3 times, the rate of change is small, and the decrease or increase in heat generation temperature is hindered, and stable heat generation performance cannot be realized. On the other hand, when the ratio of the average particle diameter is 3 times or more, the change magnification can be 2 times or more.

  In the third invention, in particular, the carbon black included in the second invention is thermal black. Thermal black generally has a large particle diameter of 100 nm or more and is a single particle, so that the rate of change can be further increased.

  In the fourth invention, the ratio of the average particle diameter of the two types of graphite is 10 times or more. When the ratio of the average particle diameter of graphite is less than 10 times, the rate of change is small, and the lowering or raising of the heat generation temperature is hindered and stable heat generation performance cannot be realized. On the other hand, those having an average particle size ratio of 10 times or more can realize a change magnification of 2 times or more, and can obtain high conductivity.

  In the fifth invention, in particular, the resin composition included in the first invention is composed of a reactive resin that exhibits at least PTC characteristics and a composition of the reactive resin, whereby the conductor is bonded to the reactive resin. The conductive path formed by the conductor can be stabilized by capturing with the binding force. Furthermore, due to the bonding force between the reactive resin and the reactive resin that exhibits PTC characteristics, the temperature characteristics of the expansion coefficient and the change over time of the melting temperature due to repeated cooling are suppressed, and the conductive path can be further stabilized. . As a result, physical, chemical, and electrical behavior can be stabilized, so that stable PTC characteristics can be realized over a long period of time.

In the sixth invention, in particular, the resin composition contained in the resistor composition B of the fifth invention is mainly composed of a carboxyl group, a carbonyl group, a hydroxyl group, an ester group, a vinyl group, an amino group, an oxazoline group, anhydrous A reaction resin containing at least one functional group of a maleic acid group, and a main component containing at least one functional group of an epoxy group, an oxazoline group, or a maleic anhydride group different from the functional group of the reaction resin By using a composition comprising a reactive resin, a chemical bond is formed between the reactive resin and the functional group having the polarity of the reactive resin by a reaction, and the thermal stability of the reactive resin alone can be enhanced. . Thereby, similarly to the fifth invention, physical, chemical, and electrical behavior can be stabilized, so that stable PTC characteristics can be realized over a long period of time.

  In the seventh aspect of the invention, in particular, by constituting the electrically insulating base material of the first aspect of the invention with at least one of a woven fabric and a non-woven fabric, the planar heating element is imparted with flexibility and easy even when an external force is applied. It is possible to improve the seating feeling when it is deformed to be used as a car seat heater.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the present embodiment. In addition, a configuration unique to each embodiment can be combined as appropriate.

(Embodiment 1)
1 and 2, a planar heating element 1 includes an electrically insulating substrate 2, a first filament electrode (hereinafter referred to as a filament electrode) 3A, a second filament electrode (hereinafter referred to as a filament electrode) 3B, and a polymer. A resistor 5.

  Hereinafter, the line electrodes 3A and 3B may be collectively described as the line electrode 3. The linear electrodes 3A and 3B are arranged on the electrically insulating base material 2 so as to be symmetrical with each other, and are partially sewn with a thread 4.

  The polymer resistor 5 is formed on the electrically insulating base material 2 on which the filament electrodes 3 are arranged by being extruded into a film by, for example, a T-die extrusion method.

  As a result, the polymer resistor 5 is thermally fused to the filament electrode 3 and the electrically insulating substrate 2.

  The central portion of the sheet heating element 1 is punched after the polymer resistor 5 is thermally fused to the filament electrode 3 and the electrically insulating base material 2. Thus, the planar heating element 1 is configured.

  In addition, the lead wire for supplying the electric power from a power supply to the filament electrodes 3A and 3B is not illustrated. Further, the punching of the central portion is not limited to this place. It may be provided in a place other than this depending on the material and shape of the skin of the seat. In this case, the wiring pattern of the line electrode 3 is changed.

  3 and 4 show a seat of an automobile to which the planar heating element 1 is attached. The planar heating element 1 rises from a seat portion 6 that is a seat of the automobile as a heater for heating or from the seat portion 6. The electric insulating base material 2 is attached to the backrest 7 provided on the front side so as to be disposed on the surface side.

  A seat base 9 and an outer skin 10 are used for the seat 6 and the backrest 7. The seat base material 9 such as a urethane pad is deformed when a load is applied by a human body seated on the seat, and the shape is restored when the load is no longer applied.

  The skin 10 covers the seat base material 9. That is, the planar heating element 1 is attached by arranging the polymer resistor 5 side on the seat base material 9 and the electrically insulating base material 2 side on the skin 10.

  In addition, in order to correspond to the hanging part (not shown) of the seat part 6 and the backrest 7, the extension part (not shown) of the electrically insulating base material 2 for hanging in a center part or a peripheral part is provided. There may be.

  Thus, the thin planar heating element 1 is disposed along the seat base 9 and the skin 10 which can be deformed. Therefore, the planar heating element 1 must be similarly deformed corresponding to the deformation of the seat 6 and the backrest 7.

  Therefore, it is necessary to design various heat generation patterns and to change the arrangement shape of the line electrodes 3 for that purpose. The details are omitted here.

  A pair of wide linear electrodes 3 </ b> A and 3 </ b> B arranged so as to face each other are disposed along the outer side in the longitudinal direction of the planar heating element 1. By supplying power from the line electrodes 3A and 3B to the polymer resistor 5 disposed so as to overlap the line electrodes 3A and 3B, a current flows through the polymer resistor 5 and the polymer resistor 5 generates heat. .

  The polymer resistor 5 has a PTC characteristic, and has a self-temperature adjusting function so that the resistance value increases as the temperature rises to reach a predetermined temperature.

  That is, the polymer resistor 5 gives the planar heating element 1 a function that is highly safe and does not require temperature control.

  In addition, as a car seat heater incorporated in an automobile seat, the planar heating element 1 can satisfy a seating feeling and flame retardancy.

  The seating sensation is satisfactory because there is no squeaking like paper and an elongation characteristic equivalent to that of the seat skin material, that is, a load of 7 kgf or less for an elongation of 5%.

  In addition, the planar heating element 1 having the PTC characteristic can exhibit quick heat and energy saving as compared with the heating element having no PTC characteristic.

  A heating element having no PTC characteristic requires a temperature controller, and the temperature controller controls the heat generation temperature by controlling energization by ON-OFF control. In particular, in the case of a heating element having a PTC characteristic using a filament heating wire, the heating element temperature at the time of ON is raised to about 80 ° C. in order to avoid a low temperature portion between the filament heating wires. Need to be placed at some distance.

  On the other hand, in the planar heating element 1, the heating element temperature is self-controlled within the range of 40 ° C to 45 ° C. Therefore, it can be arranged close to the vicinity of the skin 10.

  The sheet heating element 1 has a low heating element temperature and is disposed in the vicinity of the skin 10, so that it is possible to reduce the rapid heating property and heat dissipation loss to the outside. Therefore, energy saving can be realized.

  As described above, in the planar heating element 1 of the present embodiment, the conventional planar heating element has a 5-6 layer structure of a base material, an electrode, a polymer resistor, a heat-fusible resin, and a coating material. On the other hand, the planar heating element 1 has a three-layer structure of an electrically insulating substrate 2, a pair of filament electrodes 3, and a polymer resistor 5. With this simple configuration, even when an external force is applied, the restriction of the external force is reduced, and thus flexibility is easily exhibited.

  Therefore, even when subjected to an external force when used as a car seat heater, it is highly flexible and easily deformed, and cracking and peeling of the polymer resistor caused by creases as in the prior art are prevented.

Further, the planar heating element 1 can be manufactured with a simple configuration of three layers, so that the productivity is excellent and the material cost for configuring the planar heating element 1 is reduced. As a result, it can be produced at low cost.

  Further, since a resin film such as a non-breathable polyester sheet is not used with the polymer resistor 5 interposed therebetween, moisture tends to be trapped when used for a car seat heater or a handle heater as in a conventional sheet heating element. This solves the problem, and even when used for a long time, a seating feeling and a touch feeling equivalent to those in the initial stage can be obtained, and a comfortable heating effect can be obtained.

  As the electrically insulating base material 2, for example, a needle punch type nonwoven fabric made of polyester fiber is used. Besides this, a polyester woven fabric may be used. These electrically insulating base materials 2 impart flexibility to the planar heating element 1 and easily deform even when an external force is applied to improve the seating feeling when used as a car seat heater.

  In particular, when the filament electrode 3 is attached by sewing, the above nonwoven fabric and woven fabric are optimal in terms of prevention of cracks generated from the needle holes of the electrically insulating base material 2 by sewing and flexibility.

  The filament electrode 3 is attached to the electrically insulating base material 2 by sewing with a sewing machine or the like. According to the structure produced by this method, the linear electrode 3 can be firmly fixed to the electrically insulating substrate 2 and can be deformed following the deformation of the electrically insulating substrate 2, thereby improving the mechanical reliability. .

  Moreover, since the sewing to the electrically insulating base material 2 is performed by the thread 4, the selection range of the electrode material and the shape is expanded.

  Furthermore, unlike the conventional complicated comb-shaped electrode, the line electrode 3 can be a simple configuration having at least a pair of linear shapes, so that the material cost is low and the cost can be reduced.

  Further, even when an external force is applied when used as a car seat heater, the generation of wrinkles on the filament electrode 3 is suppressed, and the electrode is prevented from being damaged.

  The wire electrode 3 is composed of at least one of a metal conductor and a metal braided conductor. These materials are easy to sew to the electric base material insulation 2 and have high productivity.

  Further, the selection range of the material and shape of the metal conductor and the metal braided conductor is widened.

  Further, since the metal conductor and the metal braided conductor are excellent in flexibility and have high mechanical strength, they can endure for a long period of time even if the planar heating element is repeatedly stretched, bent, or deformed.

  In addition, since the electrode is composed of a filament, unlike the conventional complicated comb-shaped electrode, it can have a simple structure, and the cost of the electrode material can be reduced.

  The resistance of the line electrode 3 is preferably as low as possible, and the voltage drop at the line electrode 3 is preferably small.

  The linear electrode 3 has a suitable resistance value at which the voltage drop of the voltage applied to the planar heating element 1 is 1 V or less.

  Further, if the wire diameter of the filament electrode 3 is large, irregularities are formed on the planar heating element 1 and the seating feeling is impaired. Therefore, the diameter is preferably 1 mm or less. 5 mm or less is good.

Materials that realize this resistance value are copper, tin-plated copper, copper-silver alloy single wire, stranded wire,
For example, a braided wire.

  Particularly, in terms of mechanical strength, it is preferable to use copper-silver having high tensile strength.

  In this embodiment, the line electrode 3 is used as an electrode. However, the present invention is not limited to this, and a metal foil electrode, an electrode film by screen printing such as a silver paste, or the like can also be used.

  The resin composition of the polymer resistor 5 reacts with a modified polyethylene having a carboxyl group as a reaction resin that expresses PTC and a reaction resin in order to suppress a change in PTC characteristics with time and reproduce a stable PTC characteristic. What mixed the modified polyethylene which has an epoxy group as a reactive resin to perform is good. This is because the carbonyl group of the reactive resin reacts with the oxygen of the epoxy group of the reactive resin to be chemically bonded and has a crosslinked structure.

  By this crosslinking reaction, as described above, the thermal stability can be improved compared to the case of the resin alone, and as a result, the temperature at which the conductive path of the conductor in the resin composition is formed and cut is reduced. Stabilize.

  This cross-linking reaction can occur even through nitrogen in addition to oxygen. If a combination of a reactive resin having a functional group containing at least one of oxygen and nitrogen and a reactive resin having a functional group capable of reacting with these functional groups, a crosslinking reaction will occur, and the resin composition As a combination of the reactive functional group of the reactive resin and the functional group of the resin to be reacted, there are the following in addition to the above-described epoxy group and carbonyl group.

  The epoxy group undergoes addition polymerization by reacting with a carboxyl group, an ester group, a hydroxyl group, an amino group, a vinyl group, a maleic anhydride group, or an oxazoline group in addition to the above carbonyl group. A reaction resin having these functional groups may be used.

  On the other hand, as a functional group of the reactive resin, a reactive resin having an oxazoline group or a maleic anhydride group in addition to an epoxy group can be used.

  Thus, the resin composition has a structure crosslinked through at least one of oxygen and nitrogen.

  When the exothermic temperature is relatively low as 40 to 50 ° C. like a car seat heater, a modified olefin resin that is a low melting point resin such as an ethylene vinyl acetate copolymer, It is preferable to use ester ethylene copolymers such as ethylene ethyl acrylate copolymer, ethylene methyl methacrylate copolymer, ethylene methacrylic acid copolymer, and ethylene butyl acrylate.

  The above-mentioned reactive resin and reactive resin can be used either individually or in combination, and are appropriately selected according to the target PTC characteristics.

  In addition, it is also possible to use a reactive resin or a reactive resin alone depending on the allowable range of change with time in PTC characteristics.

  Moreover, although reactive resin was used for the crosslinking reaction, the crosslinking agent different from reactive resin can also be used.

  Furthermore, crosslinking means such as an electron beam can be used. In that case, the above-described reactive resin having no functional group is applicable, and it is not necessary to use a reactive resin.

  As described above, by optimizing the composition of the resin constituting the polymer resistor 5, it is possible to achieve stable film processing, excellent durability, and reliability of the polymer resistor 5, There is a problem that the PTC characteristic of the polymer resistor 5, that is, the resistance change magnification of 20 ° C. and 50 ° C. cannot be obtained twice or more.

  Therefore, a plurality of types of carbon black and graphite having different average particle diameters are used as the conductor.

  Next, an example of a method for manufacturing the planar heating element 1 will be described.

  First, the shape shown by A and B of FIG. 1 with the polyester thread | yarn 4 which used what twisted 19 copper-silver alloy wires with a diameter of 0.05 micrometer for the electrically insulating base material 2 which consists of a nonwoven fabric of a polyester fiber. The filament electrode 3 is formed by sewing with a sewing machine.

  The distance between the electrodes of the pair of filament electrodes 3 at this time is 100 mm. Next, the resin to be reacted, the reactive resin, and the conductor that express the PTC characteristics are kneaded and mixed, extruded from a T die connected to an extrusion apparatus, and molded into a film. In this way, the polymer resistor 5 is manufactured.

  In addition, kneading | mixing mixing is performed with apparatuses, such as a hot roll, a kneader, and a biaxial kneader.

  The thickness of the polymer resistor 5 is not particularly limited, but 20 to 200 μm is appropriate in terms of flexibility, material cost, appropriate resistance value, and strength when a load is applied. 30-100 micrometers is good.

  Next, the polymer resistor 5 molded into a film and extruded from the T-die is composed of the surface of the electrically insulating base material 2 to which the prefabricated linear electrode 3 is attached and the laminator. Are heat-sealed and bonded together. The planar heating element 1 is completed as described above.

  The linear electrode 3 and the polymer resistor 5, and the electrically insulating substrate 2 and the polymer resistor 5 are joined by thermal fusion, respectively. It arrange | positions in the state electrically connected between the resistors 5.

  The polymer resistor 5 is a flexible sheet or film, so that even if an external force is applied to the planar heating element 1, the polymer resistor 5 itself responds to the external force in the same manner as the electrically insulating substrate 2. Since elongation and deformation occur, breakage such as cracks and breaks of the polymer resistor 5 is prevented, and excellent durability is realized.

  Further, by forming the polymer resistor 5 in the form of a sheet or film, the film thickness can be made thicker than the polymer resistor of the printed film, and electrical connection and mechanical joining with the line electrode 3 can be achieved. The reliability will be higher.

  Furthermore, since the polymer resistor 5 continuously extruded can be bonded while being bonded to the electrically insulating substrate 2 to which the filament electrode 3 is attached, the productivity is excellent and low cost can be realized.

The polymer resistor 5 preferably has an elongation equal to or greater than that of the electrically insulating substrate 2. By making the elongation of the polymer resistor 5 equal to or greater than that of the electrically insulating substrate 2, the electrically insulating substrate 2 having high mechanical strength can regulate elongation and deformation due to external force, and thus is more excellent. Durability and reliability.

  Moreover, the polymer resistor 5 is affixed to the electrical insulating base material 2 to which the linear electrode 3 is previously attached by disposing the polymeric resistor 5 on the electrical insulating base material 2 and the linear electrode 3. A manufacturing method can be adopted. According to this manufacturing method, since the polymer resistor 5 immediately after molding is in a high temperature state, the polymer resistor 5 is easily and firmly bonded to the linear electrode 3 and the electrically insulating substrate 2. As a result, electrical connection and mechanical joining can be obtained stably.

  Further, by thermally fusing the polymer resistor 5 to the filament electrode 3, the material of the polymer resistor 5 is transferred around the filament electrode 3, and the filament electrode 3 and the polymer resistor 5 Instead of bonding, surface bonding can be used. As a result, mechanical joining and electrical connection between the line electrode 3 and the polymer resistor 5 are strengthened, and an electrically and mechanically stable planar heating element 1 can be obtained.

  The planar heating element 1 configured as described above is preferably used by being disposed on the seat portion 6 or the backrest 7 so that the electrically insulating base material 2 is on the surface side. That is, with the cushioning property of the electrically insulating base material 2, the unevenness due to the thickness and hardness of the line electrode 3 is not felt on the seating surface, and the seating feeling and the backrest feeling are not impaired.

  In Table 1, when only carbon black is added (No. 1, 2), when only graphite is added (No. 3, 4), two types of carbon black and one type of graphite (No. 5, 6) One type of carbon black and two types of graphite (No. 7), and two types of carbon black and two types of graphite are added (No. 8). From this result, the following can be derived.

That is, the change magnification (resistance value at 50 ° C./resistance value at 20 ° C.) is less than 2 (No 1 to 4) only with carbon black and with graphite alone. However, a mixture of carbon black and graphite having a mean particle size ratio of 3 times (No. 5, 6), and a mixture of graphite and carbon black having a mean particle size ratio of 11 times (No. .7) In the case where carbon black having an average particle size ratio of 3 times and graphite having an average particle size ratio of 11 times are mixed and added (No. 8), the change magnification is about 3. In addition, No. The change magnification of 7 and 8 is No. Although it is smaller than that of 5 and 6, it is considered that this is because the resistance value has decreased, and the effect of reducing the change magnification is not small. In another test, the ratio of the average particle diameter was small, and the change ratio was small, less than 2.

  The planar heating element according to the present invention has a simple configuration and is particularly excellent in PTC characteristics. Since this planar heating element can be mounted on the surface shape of an appliance having, for example, a continuous curved surface or a combination of flat surfaces, an automobile floor, a handle, and other electric floor heating that requires heating as a heater for heating, etc. Applicable to any apparatus. In addition, since the productivity is excellent and the cost can be reduced, the application range of applied products is expanded.

The top view which shows the planar heating element in Embodiment 1 of this invention Cross-sectional view of the same heating element Side view showing a car seat with the same heating element Front view of the seat Plan view of a conventional planar heating element Cross-sectional view of the same heating element Sectional drawing which shows schematic structure of an example of the preparation apparatus of the conventional planar heating element

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Planar heating element 2 Electrically insulating base material 5 Polymer resistor

Claims (7)

A resin composition in which a main component is crosslinked through a reactive resin, a conductor composed of a plurality of types of carbon black and graphite, and an electrically insulating substrate, and an average particle diameter of the plurality of types of carbon black and graphite A planar heating element comprising a polymer resistor characterized by different The planar heating element according to claim 1, wherein the ratio of the average particle diameter of the two types of carbon black is 3 times or more. The planar heating element according to claim 2, wherein one type of carbon black is thermal black. The planar heating element according to claim 1, wherein the ratio of the average particle diameter of the two types of graphite is 10 times or more. The planar heating element according to claim 1, wherein the resin composition contained in the polymer resistor comprises at least a reactive resin that exhibits PTC characteristics and a reactive resin. The resin composition contained in the polymer resistor has a main component containing at least one functional group of carboxyl group, carbonyl group, hydroxyl group, ester group, vinyl group, amino group, oxazoline group, and maleic anhydride group. The surface according to claim 5, comprising a reactive resin and a reactive resin, the main component of which includes at least one functional group of an epoxy group, an oxazoline group, and a maleic anhydride group different from the functional group of the resin to be reacted. Heating element. The planar heating element according to claim 1, wherein the electrically insulating substrate is composed of at least one of a woven fabric and a nonwoven fabric.

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