JP5126156B2 - Planar heating element - Google Patents

Description

  The present invention relates to a planar heating element that is thin, has low resistance, and has excellent PTC characteristics.

  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.

  Specifically, as shown in FIGS. 4 and 5, the sheet heating element is a pair obtained by printing and drying a conductive paste such as a silver paste on an electrically insulating base material 50 such as a polyester film. Comb-shaped electrodes 51, 52, and polymer resistor 53 obtained by printing and drying polymer resistor ink at a position where power is supplied by the comb-shaped electrodes 51, 52, and a covering material 54 made of the same material as the base material 50. The comb-shaped electrodes 51 and 52 and the polymer resistor 53 are covered and protected.

  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.

  As a result, the comb-shaped electrodes 51 and 52 and the polymer resistor 53 are isolated from the outside world and given long-term reliability (for example, see Patent Documents 1 and 2).

  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 resistance value rapidly increases. The polymer resistor 53 having this PTC characteristic Thus, a planar heating element having a self-temperature adjusting function can be provided.

  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 as anti-freezing heaters.

  FIG. 6 shows a specific configuration thereof, in which the electrode cable 56 is pulled out from the die of the extruder in parallel, and at the same time, the resistor kneaded material 57 is extruded and coated, and subsequently, the insulating coating 58 is coated around the periphery. (For example, refer 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 used is usually 1000.
For example, when it is used for a DC-driven heating element for automobiles, power is supplied in close proximity like a comb-shaped electrode having an interval of several millimeters.

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

  On the other hand, the exothermic heating element has a thickness in millimeters compared to that used for 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 is bonded to a first flame retardant hot melt film bonded onto a flame retardant substrate and the first flame retardant hot melt film. A film-like flame retardant PTC resistor, a pair of flame retardant electrodes for feeding power between the flame retardant PTC resistors, and a second coating covering the flame retardant PTC resistor and the pair of flame retardant electrodes. A metal twisted gland comprising a flame retardant hot melt film and a flame retardant coating material on which the second flame retardant hot melt film is bonded, and coated with a flame retardant film resistor as the flame retardant electrode Was used.

  ADVANTAGE OF THE INVENTION According to this invention, while being able to express a high PTC characteristic with low resistance, a highly reliable planar heating element can be provided.

The top view which shows the planar heating element in Embodiment 1 of this invention XY sectional view of FIG. Expanded cross section of flame retardant electrode Plan view showing a conventional planar heating element XY sectional view of FIG. Sectional drawing which shows another conventional heating element

According to a first aspect of the present invention, there is provided a first flame retardant hot melt film bonded onto a flame retardant substrate, and a film-like flame retardant PTC resistor bonded onto the first flame retardant hot melt film. A pair of flame retardant electrodes for supplying power to the flame retardant PTC resistor, a second flame retardant hot melt film covering the flame retardant PTC resistor and the flame retardant electrode, and the second flame retardant A metal stranded gland coated with a flame retardant film resistor was used as the flame retardant electrode.

With this configuration, both sides of the film-like flame retardant PTC resistor are covered with the first and second flame retardant hot melt films, which can exhibit high PTC characteristics with low resistance and have high reliability. A heating element can be provided.
In addition, the electrical connection between the metal stranded wire and the flame retardant PTC resistor is more reliable through the flame retardant coated resistor, and fire hazards such as fire and smoke due to sparks when the metal stranded wire is disconnected (hereinafter referred to as “fire hazard”) , And abbreviated as FH).

  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.

With this configuration, 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.

  In the third invention, in particular, in the first or second invention, the flame retardant PTC resistor is used as a film by calendering.

  With this configuration, it is possible to obtain a thin-film / film-like flame-retardant PTC resistor having a thickness of 400 micrometers or less, preferably 75 to 200 micrometers.

In particular, according to a fourth invention, in the first 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.

  With this configuration, it is possible to ensure both adhesion to the metal and the flame retardant PTC resistor. Further, the FH effect can be enhanced by the conductive whisker.

In the fifth invention, in particular, in the first invention, the first and second flame retardant hot melt films are crystalline polyester resins hardly soluble in organic solvents having a molecular weight in the range of 10,000 to 30,000. The flame retardant of the first flame retardant hot melt film was higher than the melting point of the second flame retardant hot melt film.

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

In particular, the sixth invention provides flame retardancy by using a flame retardant nonwoven fabric or a flame retardant polyester film as the flame retardant substrate and the flame retardant coating material in the first invention. Can be given and improved.

In a seventh aspect of the invention, in particular, in the first aspect of the invention, a flame retardant PTC resistor is bonded in a film shape by calendering on the surface of the first flame retardant hot melt film bonded on the flame retardant substrate. The flame retardant electrodes are arranged at regular intervals on the flame retardant PTC resistor, and all of them are heated with the second flame retardant hot melt film bonded to the flame retardant coating material facing. By fusing, a planar heating element with excellent mass productivity can be provided.

In an eighth aspect of the present invention, any one of the first to seventh planar heating elements is mounted on a vehicle seat device as a heating heat source.

In a ninth aspect of the present invention, any one of the first to seventh planar heating elements is mounted on an automotive handle device as a heating heat source.

  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)
1 to 3, for example, a nitrogen / phosphorous powdery difficulty is produced by a T-die extrusion method on a flame-retardant substrate 2 made of a needle punch made of flame-retardant polyester fiber impregnated and dried with a flame retardant. 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. The first flame retardant hot melt film 3 having a thickness of 55 micrometers is bonded together, and the flame retardant PTC resistor 4 is deposited on the first flame retardant hot melt film 3 by a calendering method. A pair of flame retardant electrodes 5 are arranged on the film flame retardant PTC resistor 4 at an interval of 100 mm as a flame retardant coating material 6. Using the flame retardant polyester film having a thickness of 5 micrometers, the surface of the second flame retardant hot melt film 7 having a thickness of 55 micrometers bonded thereto is opposed to the flame retardant PTC resistor 4, All of these were heat-sealed to produce a planar heating element 1.

The flame-retardant PTC resistor 4 is made of a modified polyethylene resin as a crystalline resin composition, and 35 parts of an ethylene / methyl acrylate copolymer (trade name “Rotril 29MA03”, melting point 61 ° C., manufactured by Atofina Corporation). 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. , Manufactured by Sumitomo Chemical Co., Ltd.), 30 parts by weight of this crystalline resin composition, and carbon black (trade name “Printex L”, primary particle size 21 nm, Degussa Co., Ltd.), carbon black (trade name “# 10B”, primary particle size 79 nm, manufactured by Mitsubishi Chemical Corporation), graphite (trade name “CGB-15”, spherical graphite) 56% by weight in combination with Nippon Graphite Co., Ltd., and 13% by weight of liquid flame retardant (trade name “CR-733S”, phosphate ester liquid flame retardant, manufactured by Daihachi Chemical Co., Ltd.) As additive, polytetrafluoroethylene (PTFE) acrylic-modified additive (trade name “Metabrene A3000”, manufactured by Mitsubishi Rayon Co., Ltd.) 2.5% by weight, titanium coupling agent (trade name “Plenact KR”) -44 ", manufactured by Ajinomoto Fine Techno Co., Ltd.) 2.5% by weight.
The flame retardant electrode 5 is arranged symmetrically with a pair of a stranded metal wire 8 made of copper-silver alloy wire covered with a flame retardant coating resistor 9 as a pair.

  The second flame retardant hot melt film 6 is 25% by weight of a nitrogen / phosphorous powdered flame retardant (trade name “ADK STAB FP-2100J”, white powder, manufactured by Asahi Denka Kogyo Co., Ltd.) by a T-die extrusion method. A kneaded crystalline polyester resin (trade name “Byron GM920”, melting point 107 ° C., manufactured by Toyobo Co., Ltd.) was produced with 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 9 is made of, as a modified polyethylene resin, 35 parts of an ethylene / methyl acrylate copolymer (trade name “Rotril 29MA03”, melting point 61 ° C., manufactured by Atofina), ethylene / methacrylic. 35 parts of an acid methyl copolymer (trade name “Acrylift WH206”, melting point 86 ° C., manufactured by Sumitomo Chemical Co., Ltd.), maleic anhydride-modified polyethylene (trade name “Rotada LX-4110”, melting point 107 ° C., manufactured by Arkema ) 30 parts of a resin composition, 26% by weight of this resin composition, and 11% by weight of carbon black (trade name “Printex L”, primary particle diameter 21 nm, manufactured by Degussa) as a conductor, Carbon black (trade name “# 10B”, primary particle diameter 79 nm, manufactured by Mitsubishi Chemical Corporation) 22% by weight and conductive whisker (trade name “FTX-14-6”) , Ishihara Sangyo Co., Ltd.) 26% by weight, liquid flame retardant (trade name “CR-733S”, phosphate ester liquid flame retardant, manufactured by Daihachi Chemical Co., Ltd.) 11.5% by weight, processing aid 2.5% by weight of an additive obtained by subjecting polytetrafluoroethylene (PTFE) to acrylic modification as an agent (trade name “Metabrene A3000”, manufactured by Mitsubishi Rayon Co., Ltd.)
A titanium-based coupling agent (trade name “Plenact KR-44”, manufactured by Ajinomoto Fine Techno Co., Ltd.) 1% by weight as a stabilizer was prepared by kneading.

  Note that lead wires for supplying power to the pair of flame retardant electrodes 5 are omitted. Moreover, it is needless to say that the arrangement shape of the flame-retardant electrode 3 needs to be changed according to various heat generation patterns, but is omitted here.

  In the above embodiment, the sheet resistance of the obtained sheet heating element 1 was 25Ω □ (20 ° C., film thickness of the flame-retardant PTC resistor 4 is 100 micrometers).

  The specific resistance in the case of a two-row arrangement configuration with an area of 300 mm × 350 mm square with 3 mm of flame retardant electrodes (corresponding to a length of 600 mm with 3 mm of flame retardant electrodes) is about 0.25 Ω · cm. there were.

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

  The specific resistance of the carbon black / graphite system used in the flame retardant PTC resistor of this example is considered to be 0.03 Ω · cm.

  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 4 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 1. And it can use as a car seat heater built in the seat for cars, or a radiation heater for cars.

  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 disposed 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 4 (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 about the planar heating element 1 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 and partial compatibilization of the first and second flame retardant hot melt films into the flame retardant PTC resistor 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.

  Hot melt material (flame retardant second hot melt film) with lower melting point is considered to penetrate more, but it alone lacks heat resistance, so it is combined with flame retardant first hot melt film with higher melting point) -ing

  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 a bunch of cocoons. It is correlated with oil absorption.) However, such conductive carbon black has a PTC characteristic on the other hand. It had the disadvantage of being difficult to express.

  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 diameter 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 a 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.

DESCRIPTION OF SYMBOLS 1 Planar heating element 2 Flame retardant base material 3 1st flame retardant hot melt film 4 Flame retardant PTC resistor 5 Flame retardant electrode 6 Flame retardant coating material 7 2nd flame retardant hot melt film 8 Collective metal Stranded wire 9 Flame retardant coated resistor

Claims (9)

A first flame retardant hot melt film bonded on a flame retardant substrate, a film-shaped flame retardant PTC resistor bonded on the first flame retardant hot melt film, and the flame retardant PTC A pair of flame retardant electrodes for supplying power to the resistor, these flame retardant PTC resistors, a second flame retardant hot melt film covering the flame retardant electrode, and the second flame retardant hot melt film are bonded together. A planar heating element comprising a metal twisted gland coated with a flame retardant film resistor as the flame retardant electrode . 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. As a flame retardant film resistor, and at least modified polyethylene resin, a conductor comprising a conductive whisker, a flame retardant, the sheet heating element according to claim 1, wherein comprising a coupling agent. The first and second flame retardant hot melt films comprise at least an organic solvent-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 hot melt film. The planar heating element according to claim 1, wherein the melting point is higher than the melting point of the second flame-retardant hot melt film. The planar heating element according to claim 1, wherein a flame-retardant nonwoven fabric or a flame-retardant polyester film is used as the flame-retardant substrate and the flame-retardant coating material. A flame retardant PTC resistor is pasted on the surface of the first flame retardant hot melt film laminated on the flame retardant substrate by calendering, and the flame retardant PTC resistor is difficult on the flame retardant PTC resistor at regular intervals. The planar heating element according to claim 1, wherein all of these are heat-sealed in a state where the flame-retardant electrode is disposed and the second flame-retardant hot melt film bonded to the flame-retardant coating material is opposed. An automobile seat device equipped with the planar heating element according to any one of claims 1 to 7 as a heating heat source. An automotive handle device equipped with the planar heating element according to any one of claims 1 to 7 as a heating heat source.