JP2010257683A - Planar heating element, and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a planar heating element having high reliability as well as low resistance and high PTC characteristics. <P>SOLUTION: This planar heating element is composed of two film-like flame retardant PTC resistors 3, a pair of flame retardant electrodes 4 for feeding, which are disposed between the two flame retardant PTC resistors 3, a first flame retardant hot melt film 5 disposed between a pair of the flame retardant electrodes 4 and between the two flame retardant PTC resistors 3, and a flame retardant coating material 1 on which a second flame retardant hot melt film 2 for coating the surfaces of the two flame retardant PTC resistors 3 opposite to the flame retardant electrodes 4 is pasted. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a sheet heating element having a thin wall, low resistance, and excellent PTC characteristics, and a method for manufacturing the same.

  Conventionally, for this type of planar heating element, a base polymer and a conductive material such as carbon black, metal powder, and graphite are dispersed in a solvent to form a resistor ink, which is then printed and dried on a substrate for energization. The resistor composition that generates heat is used.

  In particular, many have a PTC characteristic using a crystalline resin as a base polymer (see, for example, Patent Documents 1, 2, and 3).

  4 and 5 show a specific configuration of a conventional sheet heating element having PTC characteristics. A conductive paste such as a silver paste is printed on an electrically insulating substrate 50 such as a polyester film. A pair of comb-shaped electrodes 51 and 52 obtained by drying, and a polymer resistor 53 obtained by printing and drying polymer resistor ink at a position to which power is supplied by this, are provided, and the same as the substrate 50 The comb-shaped electrodes 51 and 52 and the polymer resistor 53 are covered and protected by the covering material 54 of the material.

  In the case of using a polyester film as the base material 50 and the covering material 54, for example, a modified polyethylene-based heat-fusible resin 55 is bonded to the covering material 54 in advance, and the pressure is applied while applying heat (pressure during heating). Thus, the base material 50 and the covering material 54 are joined via the heat-fusible resin 55.

  Thereby, the comb-shaped electrodes 51 and 52 and the polymer resistor 53 are isolated from the outside world, and long-term reliability is imparted.

  The PTC characteristic means a resistance temperature characteristic (Positive Temperature Coefficient) in which the resistance value increases as the temperature rises, and when the temperature reaches a certain temperature, the polymer resistor 53 having the PTC characteristic A planar heating element having a self-temperature adjusting function can be provided (see, for example, Patent Documents 1 and 2).

  In addition, the resistor composition was not formed as an ink, but was formed by extruding a kneaded material prepared by kneading a crystalline resin as a base polymer and a conductive material such as carbon black or graphite together with an electrode cable. Some are used, for example, as a freezing prevention heater.

  FIG. 6 shows a specific configuration of the conventional cable-shaped heating element. While the electrode cable 56 is pulled out from the die of the extruder in parallel, the resistor kneaded material 57 is extruded and coated around the electrode cable 56, and subsequently, the periphery of the electrode cable 56 is coated around the periphery. The insulating coating material 58 is covered (see, for example, Patent Document 3).

Japanese Patent Laid-Open No. 56-13689 JP-A-6-96843 JP-A-8-120182

  However, in the conventional configuration, the specific resistance of the resistor composition to be used is usually 10,000 Ω · cm or more. Therefore, for example, when used for a DC-driven heating element for automobiles, a comb shape having a spacing of several millimeters is used. Like the electrode, the power was supplied very close.

  Usually, the comb-shaped electrode is expensive because it is formed on a silver paste by printing and drying.

  On the other hand, the cable-shaped heating element formed by extrusion molding has a thickness in millimeters as compared with that used for the ink, and the electrode cables are close to each other and cannot be said to be a planar heating element.

  SUMMARY OF THE INVENTION In view of the above-described problems of the conventional technology, the problem to be solved by the present invention is to provide a sheet heating element having a thin PTC characteristic having a low specific resistance and high reliability.

  In order to solve the above-described problems, a planar heating element of the present invention includes two film-shaped flame retardant PTC resistors and a pair of power feeding units disposed between the two flame retardant PTC resistors. A flame retardant electrode, a first flame retardant hot melt film disposed between the two flame retardant PTC resistors, and the two flame retardant PTC resistors. It comprises a flame retardant coating material to which a second flame retardant hot melt film that covers the opposite surface of the flame retardant electrode is attached.

  With this configuration, the flame retardant hot melt film A is disposed between two flame retardant PTC resistors, and the flame retardant hot melt film B is disposed on the coating surface, and can exhibit high PTC characteristics with low resistance. A highly reliable planar heating element can be provided.

  According to the planar heating element of the present invention, high resistance and high PTC characteristics can be exhibited, and reliability can be improved.

The top view which shows the planar heating element in Embodiment 1 of this invention XY sectional view of FIG. Cross section of flame retardant electrode Plan view of a conventional planar heating element XY sectional view of FIG. Sectional view of a conventional cable-shaped heating element

  The first invention includes two film-like flame retardant PTC resistors, a pair of flame retardant electrodes for power feeding disposed between the two flame retardant PTC resistors, and these flame retardant properties. A first flame retardant hot melt film disposed between the two flame retardant PTC resistors between the electrodes, and a second flame retardant electrode covering the opposite surfaces of the flame retardant electrodes of the two flame retardant PTC resistors. 2 It is comprised from the flame-retardant coating material which stuck the flame-retardant hot-melt film.

With this configuration, since the first flame retardant hot melt film is disposed between the two flame retardant PTC resistors and the second flame retardant hot melt film is disposed on the coated surface, low resistance and high PTC characteristics are achieved. It is possible to provide a planar heating element that can be expressed and has high reliability.

  According to a second invention, in particular, in the first invention, the flame retardant PTC resistor comprises at least a modified polyethylene resin, an oxidized polyethylene wax, a conductor, a liquid flame retardant, and a coupling agent. Therefore, it is possible to provide a PTC resistor composition part having a saturated exothermic temperature between room temperature and about 100 ° C. and having high flame retardancy and high reliability.

  According to a third aspect of the present invention, in particular, in the first or second aspect of the present invention, the flame retardant PTC resistor is formed into a film by calendering, so that the thickness is 400 micrometers or less, preferably 75 to 200 micrometers. It is possible to make a flame-retardant PTC resistor having a thin wall and film shape.

  In a fourth aspect of the invention, in particular, in the first aspect of the invention, the flame retardant electrode is composed of a metal strand gland coated with a flame retardant film resistor, so that a metal stranded wire, a flame retardant PTC resistor, Can be more reliably connected through the flame-retardant covering resistor, and fire hazards (hereinafter abbreviated as FH) such as fire and fuming due to sparks at the time of disconnection of the metal stranded wire can be suppressed.

  In a fifth aspect of the invention, in particular, in the fourth aspect of the invention, the flame retardant film resistor comprises at least a modified polyethylene resin, a conductor containing conductive whiskers, a flame retardant, and a coupling agent. Both the adhesion to the metal and the flame retardant PTC resistor can be ensured, and the FH effect can be enhanced by the conductive whisker.

  According to a sixth invention, in particular, in the first invention, the first and second flame retardant hot-melt films are at least a crystalline polyester resin having a molecular weight in the range of 10,000 to 30,000. And t1 ≦ t2, where the melting point of the first flame retardant hot melt film is t1 and the melting point of the second flame retardant hot melt film is t2.

  Thereby, it is possible to provide a planar heating element that can be integrated with the flame-retardant PTC resistor and exhibit high PTC characteristics with a low resistance value and that has high reliability (particularly heat resistance).

  In a seventh aspect of the invention, in particular, in the first aspect of the invention, the flame retardant coating material can impart and improve flame retardancy by using a flame retardant nonwoven fabric or a flame retardant polyester film. it can.

  In the eighth and ninth inventions, the planar heating element according to any one of the first to seventh inventions is mounted on an automobile seat device or an automobile handle device as a heat source for heating, so that it is comfortable for driving in a winter season or the like. It is the one that has improved the nature.

  According to a tenth aspect of the present invention, a flame retardant PTC resistor is pasted on a second flame retardant hot melt film surface affixed on a flame retardant coating material by calendering, and then these flame retardant PTC resistors are bonded. The surface where the body surfaces are opposed to each other, and the flame-retardant electrodes are arranged at regular intervals therebetween, and at the same time, the first flame-retardant hot melt film is interposed between the flame-retardant electrodes, and then all of them are thermally fused. It is a manufacturing method of a heating element.

  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.

(Embodiment 1)
In FIG. 1 to FIG. 3, for example, a flame retardant covering material 1 produced by needle punching a flame retardant polyester fiber impregnated and dried with a flame retardant is applied to a nitrogen / phosphorous powder powder by a T-die extrusion method. Crystalline polyester resin (trade name “Byron GM925”), kneaded at 25% by weight of a flame retardant (trade name “Adekastab FP-2100J”, white powder, manufactured by Asahi Denka Kogyo Co., Ltd.), Toyobo Co., Ltd. Manufactured as a second hot melt film 2 having a thickness of 55 micrometers.

  A flame retardant PTC resistor 3 was formed on the second hot melt film 2 into a film having a thickness of 100 micrometers by a calendar method.

  The two film-like flame retardant PTC resistors 3 are opposed to each other, a pair of flame retardant electrodes 4 are arranged at an interval of 100 mm therebetween, and the flame retardant PTC resistor 3 is interposed between the pair of electrodes. The first flame-retardant hot melt film 5 having a thickness of 55 micrometers was interposed therebetween, and these were all heat-sealed to produce a planar heating element 6.

  The flame retardant PTC resistor 3 is an ethylene / methyl acrylate copolymer (trade name “Rotoril 29MA03”, melting point 61 ° C., manufactured by Atofina Corporation) as a modified polyethylene resin which is a crystalline resin composition. , 35 parts of oxidized polyethylene wax (trade name “NPS-9125”, freezing point 66 ° C., manufactured by Nippon Seiki Co., Ltd.), ethylene / methyl methacrylate copolymer (trade name “ACRIFTH WH206”, melting point 86 ° C., Composed of 30 parts by Sumitomo Chemical Co., Ltd., 26% by weight of this crystalline resin composition, and three types of conductors, carbon black (trade name “Printex L”, primary particle size 21 nm, Degussa ), Carbon black (trade name “# 10B”, primary particle diameter 79 nm, manufactured by Mitsubishi Chemical Corporation), graphite (trade name “CGB-15”, spherical graphite, Japan) 56% by weight in combination with Graphite Co., Ltd., 13% by weight of liquid flame retardant (trade name “CR-733S”, phosphate ester liquid flame retardant, manufactured by Daihachi Chemical Co., Ltd.), and processing aid 2.5% by weight of a polytetrafluoroethylene (PTFE) acrylic-modified additive (trade name “Metablene A3000”, manufactured by Mitsubishi Rayon Co., Ltd.), a titanium coupling agent (trade name “Plenact KR-” 44 ", manufactured by Ajinomoto Fine Techno Co., Ltd.) 2.5% by weight.

  The flame retardant electrode 4 is symmetrically arranged as a pair of a stranded wire 7 made of a copper-silver alloy wire covered with a flame retardant coating resistor 8.

  And the 1st flame retardant hot-melt film 5 arrange | positioned between this pair of flame retardant electrodes 4 is a powdery flame retardant of nitrogen and phosphorus type | system | group (brand name "Adekastab FP-2100J" by T-die extrusion method, A crystalline polyester resin (trade name “Byron GM920”, melting point 107 ° C., manufactured by Toyobo Co., Ltd.), in which 25% by weight of white powder, manufactured by Asahi Denka Kogyo Co., Ltd., was kneaded, was prepared to a thickness of 55 micrometers .

  As a method for heat-sealing the constituent members, any of a hot press method and a heat laminating method can be used.

In addition, the flame retardant coated resistor 8 is made of a modified polyethylene resin, 35 parts of ethylene / methyl acrylate copolymer (trade name “Rotril 29MA03”, melting point 61 ° C., manufactured by Atofina Co., Ltd.), and ethylene / methacrylic. 35 parts of an acid methyl copolymer (trade name “Acrylift WH206”, melting point 86 ° C., manufactured by Sumitomo Chemical Co., Ltd.) and maleic anhydride-modified polyethylene (trade name “Rotada LX-4110”, melting point 107 ° C., Arkema The resin composition is composed of 30 parts, and the resin composition is 26% by weight, and carbon black (trade name “Printex L”, primary particle size 21 nm, manufactured by Degussa) is 11% by weight as a conductor. , Carbon black (trade name “# 10B”, primary particle diameter 79 nm, manufactured by Mitsubishi Chemical Corporation) 22% by weight, conductive whisker (trade name “FTX-14-6”, Ishihara Sangyo Co., Ltd.) 26% by weight, liquid flame retardant (trade name “CR-733S”, phosphate ester type liquid flame retardant, manufactured by Daihachi Chemical Co., Ltd.) 11.5% by weight, processing aid 2.5% by weight of polytetrafluoroethylene (PTFE) acrylic-modified additive (trade name “Metablene A3000”, manufactured by Mitsubishi Rayon Co., Ltd.), titanium coupling agent (trade name “ Pre-act KR-44 ", manufactured by Ajinomoto Fine Techno Co., Ltd. 1% by weight was prepared by kneading.

  Note that lead wires for supplying power to the pair of flame retardant electrodes 4 are omitted. Moreover, it is needless to say that the arrangement shape of the flame-retardant electrode 4 needs to be changed depending on various heat generation patterns, but is omitted here.

  In the above-described embodiment, the sheet resistance of the obtained sheet heating element 6 was 25Ω □ (20 ° C., the film thickness of the flame-retardant PTC resistor 3 is 100 micrometers).

  The specific resistance when the flame retardant electrodes 4 are arranged in two rows at an interval of 100 mm in a 300 mm × 350 mm square area (corresponding to a length of 600 mm with the interval of the flame retardant electrodes 3 of 100 mm) is about 0.25 Ω · cm Met.

  The film thickness in the calendar process is at least 75 micrometers, and the roll coater process is 10 micrometers.

  In addition, as the specific resistance, 0.03 Ω · cm is regarded as the lower limit in the carbon black / graphite system used in the flame-retardant PTC resistor of the present embodiment.

  Therefore, addition of metal powder is indispensable for realizing a specific resistance of 0.1 Ω · cm or less, but conduction cannot be ensured unless the metal powder is highly filled.

  I think it is not applicable to resin compounds used for calendering. Resistor ink used for roll coater processing can be sufficiently applied.

  This time, the obtained flame retardant PTC resistor 3 has PTC characteristics, and when the temperature rises, the resistance value rises, and it has a self-temperature adjustment function so that it becomes a predetermined temperature, so temperature control is unnecessary Thus, it has a function as the highly safe planar heating element 6.

  It can be used as a heat source incorporated in an automobile seat device or a radiation heat source for an automobile.

  As a planar heating element having PTC characteristics, quick heat and energy saving can be exhibited as compared with a conventional heating element using a tubing heater.

  A tube heater that uses a heating element requires a temperature controller, and the heating temperature is controlled by controlling energization by ON-OFF control.

  Since the heater wire temperature at the time of ON rises to about 80 ° C., it is necessary to dispose it at a certain distance from the seat skin material. On the other hand, in the planar heating element of this embodiment, the heating temperature is high. Since it is self-controlled within a range of 40 ° C. to 60 ° C., it can be arranged close to the vicinity of the seat skin material.

  The heat generation temperature is low, and it can be used as contact heating with the body to realize energy saving by reducing heat dissipation loss.

  In addition, by making all the structural members flame-retardant, the planar heating element of the present embodiment can be applied to the automotive interior material flame retardant standard FMVSS 302 (which can self-extinguish in addition to nonflammability due to horizontal ignition, It is possible to impart flame retardancy satisfying (compatibility if the burning speed between the lines is 80 mm / min or less).

  The flame-retardant evaluation result of the planar heating element using the flame-retardant PTC resistor 3 (flame retardant addition concentration 13% by weight) of the present embodiment was non-flammable (it is 1.5 inches after ignition). Fire extinguishing without reaching the mark).

  Moreover, 80 degreeC heat resistance evaluation, 150 degreeC heat resistance evaluation, and -20 degreeC and 50 degreeC heat cycle evaluation were implemented for the planar heat generating body 6 obtained by this Embodiment.

  As a result, the resistance value change rate was within 30% of the initial value after 500 hours, 200 hours and 200 times, respectively.

  Furthermore, the safety | security that the resistance at the time of death by 150 degreeC heat resistance evaluation becomes high was able to be ensured. Factors of stability in heat resistance evaluation include the stabilization effect of the conductor by bonding the titanium coupling agent used as a stabilizer to the conductor surface, the effect of improving the melt tension by the processing aid, Further, it was considered that the penetration of the first and second flame retardant hot melt films into the flame retardant PTC resistor and partial compatibilization were caused.

  The effect of the flame-retardant hot melt film in the present embodiment is considered as follows. That is, the PTC characteristic is attributed to the melting point of the modified polyethylene resin or oxidized polyethylene wax used as the composition.

  As in the present case, when a heating element suitable for contact heating with an exothermic temperature of 40 to 60 ° C. is used, the melting points of these modified polyethylene resin and oxidized polyethylene wax are set in the vicinity thereof. However, doing so results in a lack of heat resistance.

  Usually, the practical heat resistant temperature is often higher than the melting point of the resin or wax, and various stabilizers are therefore used. For example, it is common practice to use an organic oxide as a chemical cross-linking agent to generate a chemical bond between resin and wax molecules to improve heat resistance. However, increasing the level of crosslinking will impair the PTC properties.

  In order to exhibit high PTC characteristics with low resistance as in the present embodiment, a general stabilization method cannot be used.

  Therefore, by placing a flame retardant hot melt having a high melting point, that is, a high heat resistance around the resistor, and penetrating inside the film-like flame retardant PTC resistor produced by calendar processing, Excellent PTC due to lowering of resistance by compatibilization and strengthening of conductor path and addition of thermal characteristics of flame retardant hot melt by infiltrating inside of flame retardant PTC resistor We think that we can express characteristics.

  A hot melt material having a lower melting point (first flame retardant hot melt film) is considered to have a greater degree of penetration, but it alone lacks heat resistance, so a hot melt material having a higher melting point (first flame retardant hot melt film). Film).

  In this embodiment, in order to exhibit excellent PTC characteristics, application of a low-melting high crystalline resin such as oxidized polyethylene wax or a combination of a plurality of conductors is applied. The details of the mechanism are currently unknown, but are presumed as follows.

  First, in order to obtain a resistor composition having PTC characteristics, it is necessary to select a crystalline resin to be used that has a melting point near the exothermic saturation temperature and a high crystallinity.

  In the case of a polyethylene copolymer, the crystallinity decreases as the melting point decreases, and a steep PTC characteristic cannot be realized. The addition effect of using oxidized paraffin wax that has a high crystallinity while being low melting point and partially oxidized to improve affinity with other resins, and the size and shape of the conductive particles We think that the combination of different conductors matched.

  The conductor is required to achieve a predetermined resistance value with the smallest possible addition amount, but such a conductor is generally called conductive carbon black, and has a primary particle diameter of about 20 nm or less and a structure. (It is an aggregate of primary particles such as cocoon bunches. It is correlated with oil absorption.) However, such conductive carbon black, on the other hand, exhibits PTC characteristics. It had the disadvantage of being difficult to do.

  This is because the structure of conductive carbon black is developed, and the conductive path of the structure is not easily cut even by the change in specific volume due to the temperature of the crystalline resin (which is said to be the main cause of the PTC characteristics). It is said.

  On the other hand, the inventors have obtained as knowledge that carbon black having a large primary particle diameter has excellent PTC characteristics. Further, as the graphite, spherical graphite having a particle size larger than that of the above-described carbon black is used.

  By combining these conductors, the thickness is about 300 micrometers or less, the area resistance is 100 Ω □ or less, the specific resistance is 1 Ω · cm or less, and 20 ° C., which is one index of PTC characteristics It was possible to obtain a resistor composition in which the ratio of the resistance value of 50 ° C. to the resistance value of 2.5 was 2.5 or more, and the ratio of the resistance value of 80 ° C. to the resistance value of 20 ° C. was 7 or more.

  Although the details of the mechanism that has been able to exhibit excellent PTC characteristics despite this low resistance are unknown, the formation of a new conductive path by combining a crystalline resin and a plurality of conductors, and the flame retardant hot melt I think existence is related.

  In the above embodiment, a titanium coupling agent is used as the stabilizer, but the present invention is not limited to this.

  Chemical crosslinking agents such as organic peroxides can be used. It goes without saying that waxes such as montanic acid partly saponified esters, and plasticizers and dispersants such as other waxes may be used as necessary.

  As the material of the hot melt material, a polyester type is used, but the material is not limited to this. Urethane-based (urethane-based thermoplastic elastomer) or nylon-based (polyamide-based thermoplastic elastomer) may be used.

  Moreover, although it did not mention in particular as a shape of a conductor, you may combine with a whisker or a fiber-shaped thing other than spherical shape and an indefinite shape.

  Furthermore, although the planar heating element of this Embodiment was comprised with the structural member which has all flame retardance, it is not necessarily limited to this.

When a sheet heating element is used by being attached to another flame retardant member, for example, a metal plate, or sandwiched, the flame retardant effect of the other flame retardant member is great, making the sheet heating element difficult. It may not be necessary to make it flammable.

  As described above, the planar heating element according to the present invention has low resistance and high PTC characteristics and high reliability, and can be used as a heating element for heating a vehicle seat, a steering wheel, and other parts. it can.

6 Sheet Heating Element 1 Flame Retardant Substrate 2 Second Flame Retardant Hot Melt Film 3 Flame Retardant PTC Resistor 4 Flame Retardant Electrode 5 First Flame Retardant Hot Melt Film 6 Sheet Heating Element 7 Metal Stranded Wire 8 Flame retardant coated resistors

Claims (10)

Two film-form flame retardant PTC resistors, a pair of flame retardant electrodes for power feeding disposed between the two flame retardant PTC resistors, and the two sheets between the flame retardant electrodes A first flame retardant hot melt film disposed between the flame retardant PTC resistors and a second flame retardant hot melt covering the opposite surfaces of the flame retardant electrodes of the two flame retardant PTC resistors. A planar heating element comprising a flame retardant coating material with a film attached thereto. The planar heating element according to claim 1, wherein the flame-retardant PTC resistor comprises at least a modified polyethylene resin, an oxidized polyethylene wax, a conductor, a liquid flame retardant, and a coupling agent. The planar heating element according to claim 1 or 2, wherein the flame retardant PTC resistor is formed into a film by calendering. The planar heating element according to claim 1, wherein the flame-retardant electrode is composed of a metal twist gland coated with a flame-retardant film resistor. The sheet heating element according to claim 4, wherein the flame retardant film resistor comprises at least a modified polyethylene resin, a conductor containing conductive whiskers, a flame retardant, and a coupling agent. The first and second flame retardant hot melt films comprise at least an organic solvent poorly soluble crystalline polyester resin having a molecular weight in the range of 10,000 to 30,000, and a flame retardant, and the first flame retardant. The planar heating element according to claim 1, wherein t1 ≦ t2 is set, where t1 is a melting point of the hot melt film and t2 is a melting point of the second flame retardant hot melt film. The planar heating element according to claim 1, wherein the flame retardant coating material is a flame retardant nonwoven fabric or a flame retardant polyester film. An automobile seat device equipped with the planar heating element according to any one of claims 1 to 7 as a heat source for heating. An automotive handle device equipped with the planar heating element according to any one of claims 1 to 7 as a heat source for heating. The flame retardant PTC resistor is pasted on the second flame retardant hot melt film surface affixed on the flame retardant coating material by calendering, and then these flame retardant PTC resistor surfaces are opposed to each other. A method for producing a planar heating element in which flame retardant electrodes are arranged at regular intervals between the flame retardant electrodes, and a first flame retardant hot melt film is interposed between the flame retardant electrodes. .