JP2008293671A - Resistor composition, and surface heat generating body using this - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thin-walled and moldable resistor composition, improve flexibility, a feeling of use, and reliability of a surface heat generating body when mounted on a fixture, and realize cost down. <P>SOLUTION: The film form resistor composition 4 in which an electrode 3 is arranged on an electric insulating base material 2 is arranged and installed at right and left. The resistor composition 4 is fabricated on the electric insulating base material 2 by a T die extrusion processing or a calendar processing. That is, the surface heat generating body 1 is made by heat welding the resistor composition 4 to the electrode 3 and the electric insulating base material 2, and punching out the center part. The resistor composition 4 has a PTC characteristic, and since a resistance value increases if temperature rises, it comes to have self temperature adjusting function so that it may have a prescribed temperature, and to have a function as the surface heat generating body 1 high in safety. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a resistor composition that can be attached to a device having an arbitrary surface shape.

  Conventionally, a heat generating part of this type of sheet heating element has a base polymer and a conductive material such as carbon black, metal powder, and graphite dispersed in a solvent as a resistor ink, which is then printed and dried on a substrate. Thus, a resistor composition that generates heat when energized 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).

  5 and 6 show a conventional sheet heating element having PTC characteristics, which is obtained by printing and drying a conductive paste such as a silver paste on an electrically insulating substrate 50 such as a polyester film. Comb-shaped electrodes 51 and 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 and 52, and a covering material 54 made of the same material as the substrate 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.

  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.

  As the above-described hot pressurizing means, a laminator 58 composed of two heating rolls 56 and 57 is generally adopted as shown in FIG.

  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 It will have a self-temperature control function.

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

  However, in the conventional configuration, the multi-layer structure in which the comb-shaped electrodes 51 and 52 and the polymer resistor 53 printed on the rigid electrically insulating base material 50 such as a polyester film are similarly protected by the electrically insulating coating material 54. Depending on the material and thickness of the base material 50 and the covering material 54, the flexibility is insufficient, and the seating feeling when the planar heating element is used for a car seat heater (heater for seat heating of an automobile) or the handlebar. There was a problem that the feeling of touch when used in a heater was impaired.

  In addition, since it is composed of an electrically insulating base material 50 such as a polyester sheet that is planar and has no air permeability and a covering material 54, it is used for a car seat heater or a handle heater. There is a problem that the humidity is easily confined and the feeling of sitting and touching is lost when used for a long time.

  In the case where the resistor composition is prepared as an ink, the heating portion can be formed in a thin film of about several tens of micrometers by adjusting the coating amount, so that it is easy to exhibit the flexibility of the resistor composition itself. However, it is necessary to use an electrically insulating base material such as a polyester film having a smooth and non-impregnated surface as a surface on which the ink-like resistor composition is applied, which impairs flexibility. It was a result.

  In addition, it is necessary to use a large amount of expensive conductive paste as a comb-shaped electrode as a heating element, and it has a disadvantage that the cost is high because of a complicated multilayer structure.

  On the other hand, the resistor composition used for extrusion molding is thicker in millimeters than the one used for the ink, lacks flexibility, and has a configuration in which the electrode cables are close to each other, so it cannot be said to be a planar heating element. It was.

  There are thin-wall molding methods such as T-die extrusion and calendaring, but no resistor composition suitable for these processing methods has been proposed.

  SUMMARY OF THE INVENTION In view of the above-mentioned problems of the prior art, the problem to be solved by the present invention is to provide a resistor composition that can be molded thinly without using ink, and to provide flexibility and a surface when mounted on an instrument. It is to improve both the feeling of use and reliability of the heating element and to reduce the cost.

  In order to solve the above problems, the resistor composition of the present invention comprises at least a crystalline resin, a reactive resin, an elastomer, two or more different types of conductors, a flame retardant, and a processing aid. .

  With this configuration, the crystalline resin and the conductor can exhibit PTC characteristics, the elastomer can exhibit flexibility, and the flame retardant can exhibit flame retardancy.

  Further, the reactive resin can improve at least the bond between the conductor and the crystalline resin and the heat resistance of the crystalline resin. Furthermore, PTC characteristics can be enhanced by using a combination of conductors.

  ADVANTAGE OF THE INVENTION According to this invention, the resistor composition which has the outstanding softness | flexibility and high reliability can be provided, For example, the usability is greatly improved by employ | adopting as a planar heating element for the heating of various apparatuses. It is something that can be done.

  The first invention comprises at least a crystalline resin, a reactive resin, an elastomer, two or more different types of conductors, a flame retardant, and a processing aid.

With this configuration, the crystalline resin and the conductor can exhibit PTC characteristics, the elastomer can exhibit flexibility, and the flame retardant can exhibit flame retardancy. Further, the reactive resin can improve at least the bond between the conductor and the crystalline resin and the heat resistance of the crystalline resin. Furthermore, PTC characteristics can be enhanced by using a combination of conductors.

  In particular, according to a second invention, in the first invention, a first kneaded material made of a crystalline resin, a first conductor, and a flame retardant and a second kneaded material made of an elastomer and a second conductor are kneaded. Created.

  With this configuration, it is possible to provide a resistor composition having a sea-island configuration in which the crystalline resin composition is an island and the elastomer composition is the sea.

  In particular, the third invention provides an ethylene / vinyl acetate copolymer, an ethylene / methacrylic acid copolymer, an ethylene / methacrylic acid methyl copolymer, an ethylene / acrylic acid copolymer as the crystalline resin of the first invention. Either a polymer, an ethylene / ethyl acrylate copolymer, or a combination thereof was used.

  With this configuration, the melting point of the crystalline resin can be adjusted in the range of about 50 ° C. to 110 ° C., and the exothermic saturation temperature due to the PTC characteristic can be adjusted in the range of about 40 ° C. to 80 ° C.

  The fourth invention is particularly used as the elastomer of the first or second invention as a styrene-based, urethane-based, nylon-based thermoplastic elastomer, nitrile rubber, hydrogenated nitrile rubber, or acrylic rubber, or in combination. It was.

  With this configuration, flexibility, oil resistance and chemical resistance can be exhibited.

  In the fifth invention, in particular, a carbon-based, graphite-based, metal-based, or ceramic-based conductor is used in combination as the conductor of the first or second invention.

  With this configuration, low resistance and excellent PTC characteristics can be exhibited.

  In particular, the sixth invention is a flame retardant of the first or second invention, which is liquid at room temperature or melts at a temperature below the kneading temperature to become liquid, and is phosphorous, nitrogen, or silicone alone. Or in combination.

  With this configuration, the flame retardancy is exhibited and the PTC characteristics are compensated.

  In the seventh invention, in particular, a material obtained by impregnating a conductor with the liquid flame retardant of the sixth invention was subjected to kneading.

  With this configuration, the flame retardant can be easily handled and the kneading process can be simplified.

  In the eighth invention, in particular, a mixture of an alkyl methacrylate / alkyl acrylate copolymer and a tetrafluoroethylene copolymer was used as the processing aid of the first invention.

  With this configuration, by fibrillating ethylene tetrafluoride to form a fibrous network structure, it is possible to help disperse the conductor and improve the melt tension, thereby providing a coherent resistor composition.

  In a ninth invention, the resistor composition of the first to eighth inventions is used for a planar heating element.

  With this configuration, it is easy to exhibit flexibility as a planar heating element, and a low-cost one can be provided.

  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 show Embodiment 1 of the present invention, which is an example used for an automobile seat.

  In FIG. 1, the electrically insulating base material 2 of the planar heating element 1 is, for example, a needle punch type made of polyester fiber, and uses a flame retardant nonwoven fabric impregnated with a flame retardant.

  On this electrically insulating substrate 2, a film-like resistor composition 4 in which electrodes 3 are arranged is arranged on the left and right.

  The electrodes 3 are provided in pairs on each resistor composition 4, and are arranged by partially sewing a tin-plated stranded copper wire having a resistance value of 0.03 Ω / cm or less with a thread.

  The resistor composition 4 is formed on the electrically insulating substrate 2 by T-die extrusion processing or calendar processing. That is, the resistor composition 4 is heat-sealed to the electrode 3 and the electrically insulating base material 2, and the central portion is punched to form the planar heating element 1.

  Note that lead wires for supplying power to the pair of electrodes 3 are omitted. Further, the punching of the central portion is not limited to this place, and it may be provided at other places depending on the form of the skin material of the seat. In this case, it is necessary to change the wiring pattern of the electrode 3.

  Resistor composition 4 comprises, as a crystalline resin, an ethylene / methacrylic acid methyl copolymer (trade name “ACRIFT CM5021”, melting point 67 ° C., manufactured by Sumitomo Chemical Co., Ltd.) 30 parts, ethylene / methacrylic acid copolymer 30 parts of a polymer (trade name “Nucleel N1560”, melting point 90 ° C., manufactured by Mitsui DuPont Polychemical Co., Ltd.) and a metal coordination product of ethylene / methacrylic acid copolymer (trade name “HIMILAN 1702”, melting point 90 And 40 parts of Mitsui DuPont Polychemical Co., Ltd.).

  35% by weight of this crystalline resin, two types of conductors, carbon black (trade name “Printex L”, primary particle diameter 21 nm, manufactured by Gusa), 25% by weight, graphite (trade name “GR15”, 18% by weight of scaly graphite, manufactured by Nippon Graphite Co., Ltd., 20% by weight of a flame retardant (trade name “Reophos RDP”, phosphate ester liquid flame retardant, manufactured by Ajinomoto Co., Inc.) A first kneaded material was prepared using 2% by weight of a mixture of an alkyl acrylate / alkyl acrylate copolymer and a tetrafluoroethylene copolymer (trade name “METABREN A-3000”, manufactured by Mitsubishi Rayon Co., Ltd.). did.

  Next, as an elastomer, 40% by weight of a styrene thermoplastic elastomer (trade name “Tuftec M1943”) manufactured by Asahi Kasei Engineering Co., Ltd., carbon black (trade name “# 10B”, primary particle diameter 80 nm, Mitsubishi Chemical) A second kneaded product was prepared from 45% by weight (made by Co., Ltd.) and 15% by weight tungsten carbide (made by Izawa Metal Co., Ltd.). And the resistor composition 4 was produced by kneading an equal amount of the first kneaded material and the second kneaded material.

  As shown in FIGS. 2 and 3, the sheet heating element 1 is used as a heater for seat heating by being attached to a seat portion 6 and a backrest 7 which are seats of an automobile, and the seat portion 6 and the backrest 7 are suspended. An ear portion (an extension portion of the electrically insulating base material) is provided to be hung at the central portion or the peripheral portion so as to correspond to the recessed portion (not shown), but is omitted here.

  In addition, the seat 6 and the backrest 7 to which such a planar heating element 1 is attached are generally deformed when a load is applied by a human body seated on the seat, such as a urethane pad that is restored when the load is no longer applied. The seat base 8 and the seat skin 9 are provided. Therefore, the polymer resistor 4 side is disposed on the seat base 8 and the electrically insulating base 2 side on the seat skin 9. The planar heating element 1 attached in this manner must also undergo similar deformation corresponding to the deformation of the seat 6 and the backrest 7 described above.

  For this purpose, it is needless to say that various heat generation pattern designs and the arrangement shapes of the electrodes 3 therefor need to be changed, but they are omitted here.

  In the electrode 3, a pair of wide (electrically positive side and negative side) main electrodes 3a and 3b are arranged along the outer side in the longitudinal direction of the sheet heating element 1 so as to face each other, and overlap each other. Heat is generated by feeding power from the main electrodes 3a and 3b to the resistor composition 4 arranged in this manner.

  In the above configuration, the resistor composition 4 has a PTC characteristic, and when the temperature rises, the resistance value rises, and has a self-temperature adjustment function so as to reach a predetermined temperature, so that temperature control is unnecessary and safe. It has a function as the highly planar heat generating element 1.

  In addition, as a car seat heater incorporated in an automobile seat, a seating feeling and flame retardancy can be satisfied.

  The seating feeling can be satisfied by the fact that 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 5% elongation.

  Further, as a sheet heating element having PTC characteristics, quick heating 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 controls the heat generation temperature 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 arrange the heater wire at a certain distance from the seat skin material, whereas in the planar heating element 1 of the present embodiment, the heating temperature Is self-controlled within the range of 40 ° C. to 50 ° C., it can be placed close to the seat skin material. And since heat_generation | fever temperature is low and it is the seat vicinity, the energy saving property by reduction of rapid heat property and the thermal radiation loss to the exterior is realizable.

  Moreover, a flame retardance is realizable by mix | blending a flame retardant with the resistor composition 4 using a flame-retardant nonwoven fabric for the electrically insulating base material 2. FIG. Flame retardancy is the automotive interior material flame retardant standard FMVSS302 (single fire extinguishing as well as nonflammability due to horizontal ignition, or if the burning rate between marked lines is 80 mm / min or less It was confirmed that it can be met if the amount of the flame retardant is at least 10% by weight.

  The sheet heating element 1 obtained in the present embodiment was subjected to an 80 ° C. oven standing test, a 150 ° C. oven standing test, and a −20 ° C. and 50 ° C. heat cycle test.

  As a result, the resistance value change rate was within 30% of the initial value after 500 hours, 200 hours and 200 times, respectively. The reason for this was considered to be that the crystalline resin itself and the bonding between the crystalline resin and the conductor were attempted by a crosslinking reaction with the reactive resin.

In addition, in this embodiment, a combination of a plurality of conductors and a sea-island configuration are applied in order to exhibit excellent PTC characteristics. 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 whose melting point is in the vicinity of the exothermic saturation temperature.

  As a conductor, it is required to achieve a predetermined resistance value with as small an addition amount as possible. 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 coral, which is correlated with oil absorption.) On the other hand, such conductive carbon black 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 knowledge that carbon black having a large primary particle diameter has excellent PTC characteristics. In addition, a conductor such as graphite has a particle size larger than that of carbon black and has a layered structure such as a scale, and has a large particle size such as metal or ceramic, and has excellent amorphous conductivity. By combining these multiple conductors, the thickness is about 100 μm or less, the sheet resistance is 400Ω or less, and the like (having a small volume resistivity, 1/100 or less of carbon or graphite) The volume resistance is 4 Ω / cm or less, and the ratio of the resistance value at 50 ° C. to the resistance value at 20 ° C., which is one index of the PTC characteristics, is 1.5 or more, and 80 ° C. against the resistance value at 20 ° C. It was possible to obtain a resistor composition having a resistance value ratio of 5 or more.

  Although the details of the mechanism that was able to demonstrate excellent PTC characteristics while being 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 made liquid This is considered to be due to the fact that the large thermal expansion coefficient of the liquid could 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.

(Embodiment 2)
FIG. 4 shows a second embodiment of the present invention, which is different from FIG. 1 in that a resistor composition 4 is first heat laminated in a film form on an electrically insulating substrate 2 and then an electrode 3 is provided by sewing. In this respect, the same reference numerals are given to those having the same action as in FIG. 1, and those in the first embodiment are used for specific description.

  In order to make the electrical connection between the electrode 3 and the resistor composition 4 more reliable, the electrode 3 is previously coated with another resistor composition 4a (made by extrusion molding around the electrode 3). An electrode wire 10 is provided on the resistor composition 4 by sewing, and then subjected to a pressurizing process during heating to ensure the connection between the electrode 3 and the resistor composition 4 via the resistor composition 4a. It was.

  Even in this configuration, the planar heating element 1 as an automobile car seat heater can be provided as in the first embodiment.

In the first embodiment, the position of the electrode 3 is between the electrically insulating substrate 2 and the polymer resistor 4, whereas in the second embodiment, the position is on the resistor composition 4. Since it is easy to confirm the positions of the electrode 3 and the covered electrode wire 10, it is possible to increase the flexibility or to reliably perform a removal process for attachment.

  Furthermore, since there is a degree of freedom in the arrangement of the electrodes 3 in the subsequent process, the bonding process of bonding the resistor composition 4 to the electrically insulating substrate 2 is made common, and the planar heating element 1 having various heating patterns is designed. Has the advantage that can be done.

  Note that the resistor composition 4a does not necessarily have PTC characteristics. Moreover, since the resistor composition 4a is formed in a thin film rather than the resistor composition which has a heat generating function, it cannot be overemphasized that the volume resistance may be higher than the resistor composition which has a heat generating function.

  Furthermore, as processing aids, not only a mixture of alkyl methacrylate / alkyl acrylate copolymer and tetrafluoroethylene copolymer, but also waxes such as saponified ester of montanic acid part and acrylic functional liquid polymer, etc. Needless to say, other fluidity modifiers may be used in combination.

  As described above, the resistor composition according to the present invention is highly flexible and highly reliable, and can be used as a heating element for heating a vehicle seat, steering wheel, and other parts.

(A) is a top view which shows the planar heating element using the resistor composition in Embodiment 1 of this invention, (b) is XY sectional drawing of (a). The side view which shows the seat of the motor vehicle which attached the planar heating element in Embodiment 1 The front view which shows the seat of the motor vehicle which attached the planar heating element in Embodiment 1 (A) is a top view which shows the planar heating element using the resistor composition in Embodiment 2 of this invention, (b) is XY sectional drawing of (a). Plan view showing a conventional planar heating element XY sectional view of FIG. Schematic configuration diagram showing the bonding process of the covering material of the heating element

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Planar heating element 2 Electrically insulating base material 3 Electrode 4 Resistor composition

Claims (9)

A resistor composition comprising at least a crystalline resin, an elastomer, two or more different types of conductors, a flame retardant, and a processing aid. The resistor composition according to claim 1, wherein the resistor composition is prepared by kneading a first kneaded material made of a crystalline resin, a first conductor, and a flame retardant, and a second kneaded material made of an elastomer and a second conductor. As crystalline resin, any of ethylene / vinyl acetate copolymer, ethylene / methacrylic acid copolymer, ethylene / methyl methacrylate copolymer, ethylene / acrylic acid copolymer, ethylene / ethyl acrylate copolymer The resistor composition according to claim 1, wherein the resistor composition is used in combination. The resistor composition according to claim 1 or 2, wherein the elastomer composition is any one of or a combination of styrene, urethane, and nylon thermoplastic elastomers, nitrile rubber, hydrogenated nitrile rubber, and acrylic rubber. The resistor composition according to claim 1 or 2, wherein the conductor is a combination of carbon, graphite, metal, and ceramic conductors. 3. The resistor according to claim 1 or 2, wherein the flame retardant is liquid at ordinary temperature or melted at a temperature below the kneading temperature to be liquid, and the phosphor, nitrogen, or silicone is used alone or in combination. Composition. 7. A resistor composition according to claim 6, wherein a liquid flame retardant impregnated in a conductor is subjected to kneading. The resistor composition according to claim 1, wherein a mixture of an alkyl methacrylate / alkyl acrylate copolymer and a tetrafluoroethylene copolymer is used as a processing aid. A planar heating element using the resistor composition according to claim 1.