JP4835049B2 - Polymer resistor ink - Google Patents

Description

  The present invention relates to a polymer resistor ink having both flexibility and resistance value stability, and can be used for a heating element utilizing Joule heat of a polymer resistor.

  Conventionally, as shown in FIG. 3, this type of heating element is obtained by printing and drying a conductive paste on an electrically insulating substrate 50 such as a polyester film having a thickness of about 100 microns. A pair of comb-shaped electrodes 51 and 52 and a polymer resistor 53 obtained by printing and drying a polymer resistor ink at a position where power is supplied by the pair of comb-shaped electrodes 51 and 52 are provided. The comb-shaped electrodes 51 and 52 and the polymer resistor 53 are covered and protected. When a polyester film is used as the base material 50 and the covering material 54, for example, a polyethylene-based heat-fusible resin 55 is bonded to the covering material 54 in advance, and the base material 50 and the covering material 54 are pressed by heating. Are bonded via a heat-fusible resin 55. 3A is a partially cutaway plan view of the heating element, and FIG. 3B is a sectional view taken along the line xy of FIG. 3A. Thereby, the comb-shaped electrodes 51 and 52 and the polymer resistor 53 are isolated from the outside world and given long-term reliability. As the hot pressurizing means, a laminator provided with two hot rolls is used.

  Conventionally, examples in which a polymer resistor is formed by printing and used as a heating element include an automobile door mirror and a sink mirror for removing dew and frost. The usage pattern was not subjected to mechanical stress such as bending, but was used by being attached to the back of the mirror and fixed. Further, as a safety measure, a thermal fuse, a thermostat, or the like is attached to a portion representing the heat generation temperature of the planar heating element. In practice, a terminal is required for power supply, but this is not shown.

  As the polymer resistor ink for forming the polymer resistor 53, a kneaded material composed of a crystalline resin such as polyethylene glycol, conductive particles such as carbon black, metal powder, and graphite, and a crosslinking agent is used as a solvent. It was formed in a dispersed manner. This polymer resistor ink was printed, and the crosslinking reaction by the crosslinking agent was terminated by heat during drying (for example, see Patent Documents 1 and 2). The obtained polymer resistor 53 has PTC characteristics, and is also used as an overcurrent protection element in addition to the heating element described above.

The PTC characteristic is 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 (English meaning that the resistance has a positive temperature coefficient, an acronym for Positive Temperature Coefficient). It is attributed to the change in the conductive path due to the change in the specific volume due to the heat of the crystalline resin. The polymer resistor 53 having PTC characteristics can provide a heating element having a self-temperature adjusting function.
JP 62-156159 A JP-A-2-172179

However, the conventional polymer resistor ink uses a hard crystalline resin due to its crystallinity and is further crosslinked with a crosslinking agent. Could not be used. In particular, as a heating element that requires flexibility and stretchability, for example, it fits and deforms a human body such as a car seat heater, that is, a person's seating feeling is not impaired and careful attention is paid to safety. Application to the product was not possible.

  The aim of cross-linking with the cross-linking agent is mainly to form a cross-linked structure of the crystalline resin, and the conductive path of the conductive particles dispersed in the crystalline resin is stabilized by the cross-linked structure. In the first place, the crystalline resin has a certain degree of hardness because of its crystallinity, but the result is that the hardness is further increased by the crosslinked structure.

  Therefore, it is conceivable to add a rubber component having flexibility and elasticity, but such an elastomer has not been proposed. Elastomers are generally amorphous and have a large molecular gap, so that no means has been found for stabilizing conductive particles.

  An object of the present invention is to solve the above-described conventional problems, and to provide a highly reliable polymer resistor ink having flexibility and resistance value stability.

  In order to solve the conventional problems, the polymer resistor ink of the present invention includes conductive particles, a crystalline resin having a polar group A, an elastomer having a polar group B that reacts with the polar group A, A solvent for dissolving the crystalline resin and the elastomer.

  With this configuration, flexibility due to the elastomer and stabilization of the resistance value due to the cross-linked structure due to the interpolymer reaction between the crystalline resin and the elastomer can be achieved.

  According to the present invention, it is possible to stabilize the resistance value due to the flexibility due to the elastomer and the cross-linked structure due to the interpolymer reaction between the crystalline resin and the elastomer, and the polymer resistance excellent in flexibility and resistance value stability. Body ink can be provided.

  The first invention comprises conductive particles, a crystalline resin having a polar group A, an elastomer having a polar group B that reacts with the polar group A, and a solvent for dissolving the crystalline resin and the elastomer.

  With this configuration, it is possible to stabilize the resistance value due to the flexibility of the elastomer and the cross-linked structure due to the interpolymer reaction between the crystalline resin and the elastomer.

  In the second invention, the crystalline resin comprises a resin A having a polar group A and a resin C compatible with the resin A.

  With this configuration, it is possible to provide a PTC characteristic using a specific volume change of not only the resin A but also the resin C. Further, the reactivity can be controlled by diluting the resin A containing the polar group A with the resin C.

  In the third invention, the elastomer includes a resin B having a polar group B and an elastomer A compatible with the resin.

  With this configuration, not only the resin B but also the PTC characteristic utilizing the specific volume change of the elastomer A can be imparted. Further, the reactivity can be controlled by diluting the resin B containing the polar group B with the elastomer A.

  In the fourth invention, the elastomer includes an elastomer B having a polar group B, and an elastomer C compatible with the elastomer B.

  With this configuration, not only the elastomer B but also the PTC characteristic utilizing the specific volume change of the elastomer C can be imparted. Further, the reactivity can be controlled by diluting the elastomer B containing the polar group B with the elastomer C.

  The fifth invention comprises a polar group A and a polar group B, an epoxy group and a carboxyl group, an epoxy group and a maleic anhydride group, an epoxy group and an ester group, an epoxy group and an amino group, or an amide group, an epoxy group and a hydroxyl group, The combination is any combination of an epoxy group and an oxazoline group, an oxazoline group and a carboxyl group, an oxazoline group and a maleic anhydride group, and an oxazoline group and an ester group.

  With this configuration, it is possible to provide a combination of the polar group A and the polar group B that can efficiently perform crosslinking by an interpolymer reaction.

  In the sixth invention, as the resin A or the resin B, epoxy group-containing resin, carboxyl group-containing resin, saponified ethylene / vinyl acetate copolymer, hydroxyl group-containing resin, maleic anhydride group-containing resin, polyethylene glycol alone, Or they are used in combination.

  With this configuration, practically resin A or resin B having reactivity can be provided.

  In the seventh invention, polyethylene, ethylene / vinyl acetate copolymer, methacrylic resin, or polypropylene is used alone or in combination as the resin C.

  With this configuration, it is possible to provide a polymer resistor ink having various saturation temperatures from a low temperature to a high temperature.

  The eighth invention relates to an elastomer B as a maleic anhydride group-modified styrene thermoplastic elastomer, an epoxy group modified styrene thermoplastic elastomer, a polyamide thermoplastic elastomer, a polyester thermoplastic elastomer, a polyester copolymer, and a phenol modified acrylonitrile.・ Butadiene rubber is used alone or in combination.

  With this configuration, a practical elastomer B having reactivity can be provided.

  The ninth invention uses, as the elastomer A or the elastomer C, ethylene / propylene rubber, styrene / butadiene rubber, butadiene rubber, or butyl rubber alone or in combination.

  With this configuration, flexibility and PTC characteristics can be imparted to the resin B or the elastomer B.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment)
FIG. 1 is a schematic configuration diagram of a heating element according to an embodiment of the present invention. FIG. 1A is a partially cutaway plan view, and FIG. 1B is an xy position of FIG. It is sectional drawing.

In FIG. 1, the structure of the heating element 1 is as follows. Reference numeral 2 denotes a flexible base non-woven fabric, a spunlace 3 (weight per unit area: 40 g / m ² ) formed from a polyester fiber and a polyester straight fiber 4 arranged in a direction in which elongation is regulated (longitudinal direction of the main electrode of the electrode). Span bond (50 g / m ² basis weight) produced by bonding (trade name Milife: Nippon Oil Plast Co., Ltd., basis weight 10 g / m ² ) with a thermal dot (thermal bond) with a smaller diameter than usual. is there. Reference numeral 5 denotes a barrier base film having flexibility and stretchability, and is composed of a laminated film of a film A6 and a film B7. Film A6 comprises 50 parts of a barrier resin having resistance to various liquids (water, oil, solvent) such as an ethylene / vinyl alcohol copolymer (Eval H101B, manufactured by Kuraray Co., Ltd.) and a styrene thermoplastic elastomer (Tuftec H1062). A resin composition comprising 20 parts of a resin having a reactivity such as a flexible / stretchable resin such as Asahi Kasei Co., Ltd. and an epoxy group-containing resin (Bond First, manufactured by Sumitomo Chemical Co., Ltd.) It is bonded to the surface of the spunlace 3 of the base nonwoven fabric 2 with a thickness of 30 microns by the method. Film B7 is flexible and stretchable, such as 50 parts of a heat-resistant resin such as an olefinic thermoplastic elastomer (Zelas 5053, manufactured by Mitsubishi Chemical Corporation) and a styrene-based thermoplastic elastomer (Tuftec H1062, manufactured by Asahi Kasei Corporation). A resin composition consisting of 25 parts of resin and 25 parts of resin B such as maleic anhydride-modified polyethylene (Modic APM545, manufactured by Mitsubishi Chemical Corporation), and laminated on film A6 by T-die extrusion at a thickness of 30 microns. It is matched.

  A pair of comb-shaped electrodes 8 by printing and drying a silver paste containing carbon on the barrier base film 5 of the base nonwoven fabric 2, and a polymer resistor by printing and drying polymer resistor ink at a position where power is supplied by the electrodes 8. 9 was produced. The polymer resistor 9 has a PTC characteristic and is manufactured for a car seat so that the heat generation temperature is about 45 ° C.

  Reference numeral 10 denotes a barrier cover film, and an electrode 8 and a polymer resistor 9 formed on the barrier base film 5 by printing and drying are thermally bonded to each other between the barrier base film 5 and the barrier cover film 10. It is to seal and shield from the outside world to protect them. As characteristics, it softens at a temperature lower than the softening temperature of the barrier base film 5 (has a low melting point), has flexibility / stretchability, the barrier base film 5, the electrode 8, and the polymer resistor. Adhesion with 9 is required. Here, it is configured as a laminated film of the film C11 and the film D12. The film C11 is bonded to the cover nonwoven fabric 13 with a thickness of 30 microns by T-die extrusion as a resin composition similar to the film A (in this case, resin A = resin C). The cover nonwoven fabric 13 was an orthogonal fiber type nonwoven fabric having a weight of 6 g, such as TY0303E (manufactured by Nippon Steel Plast Co., Ltd.).

  The film D12 is a flexible / stretchable resin 25 such as 50 parts of a low melting point resin such as ultra-low density polyethylene (Excellen VL200, manufactured by Sumitomo Chemical Co., Ltd.) and a styrene-based thermoplastic elastomer (Tuftec H1062, manufactured by Asahi Kasei Co., Ltd.). Part and resin D25 part such as carboxyl group-containing polyethylene (Nucleel N1525, manufactured by Mitsui DuPont Polychemical Co., Ltd.), and laminated on the film C11 by T-die extrusion at a thickness of 30 microns. .

  The barrier cover film 10 and the barrier base film 5 are heat-sealed by a laminator, and the electrode 8 and the polymer resistor 9 are sealed between the barrier base film 5 and the barrier cover film 10 to heat the heating element 1. Was made. In practice, it is necessary to form a terminal portion for supplying power on the electrode 8, but it is omitted here.

  The polymer resistor ink comprises a kneaded product of a crystalline resin containing an epoxy group as a polar group A (bond first, manufactured by Sumitomo Chemical Co., Ltd.) and carbon black, and a maleic anhydride-modified styrene thermoplastic elastomer (Tuftec). M1913, manufactured by Asahi Chemical Co., Ltd.) was made into an ink with a solvent. As the solvent, an aromatic hydrocarbon-based, aliphatic hydrocarbon-based, or glycol ether-based mixed solvent was used.

Polymer resistor 9 obtained by screen-printing and drying this polymer resistor ink
The heating element using the pliant had flexibility and a satisfactory seating feeling as a car seat heater. FIG. 2 shows an image diagram of the polymer resistor 9. 14 is an elastomer part, 15 is a crystalline resin part, 16 is a reaction product formed by the reaction of the polar group A of the crystalline resin and the polar group B of the elastomer. In addition, although electroconductive particle exists mainly in the crystalline resin part 15, it is not illustrated.

  Moreover, the resistance value change after 1 million times was within 20% of the initial stage by the vibration durability evaluation. Furthermore, even after 3,000 hours in an 80 ° C. furnace, the change in resistance value was within 20% of the initial value.

  Vibration durability evaluation is one of the evaluation methods as a car seat heater, and it is a test in which a hemisphere with a diameter of 165 mm is repeatedly pushed 50 mm from the seat surface assuming a human kneecap in the state of being incorporated in the car seat. Yes, the heating element and polymer resistor can be repeatedly displaced. When the elastomer was not used for the polymer resistor ink, a sense of incongruity was generated when seated, and the resistance value doubled after about 500 times according to the vibration durability evaluation. At this time, the polymer resistor had cracks.

  The point of the polymer resistor ink of the present invention is to provide flexibility by using a crystalline resin and an elastomer, and without using a general crosslinking agent such as peroxide, The polar group B of the elastomer is dried and reacted by a heat treatment in a subsequent process, thereby forming a crosslinked structure in the polymer resistor, thereby stabilizing the resistance value.

  Next, a second embodiment will be described. In the above embodiment, one type of modified polyethylene was used as the crystalline resin containing the polar group A in the polymer resistor ink, but the resin A having the polar group A and the resin C compatible with the resin A were used. And are used. For example, an epoxy group-modified polyethylene was used as the resin A, and an ethylene / vinyl acetate copolymer was used as the resin C compatible with the resin A.

  With this configuration, the polymer resistor can be provided with PTC characteristics utilizing a change in the specific volume of not only the resin A but also the resin C. Further, the reactivity with the elastomer can be adjusted by adjusting the concentration of the polar group A of the resin A.

  Next, a third embodiment will be described. In the first embodiment, one type of modified elastomer was used, but the elastomer is compatible with a resin B having a polar group B such as a carboxyl group (Nucrel N1525, manufactured by Mitsui DuPont Chemical Co., Ltd.). Ethylene / propylene rubber was used as the elastomer A.

  With this configuration, the elastomer can be involved in the PTC characteristics, and the reactivity with the crystalline resin can be adjusted by adjusting the concentration of the polar group B of the resin B.

  The significance of adjusting the reactivity is related to the PTC characteristics and the solubility in the solvent, and an optimum state can be created.

  Next, a fourth embodiment will be described. In the above embodiment, the resin B having flexibility is used, but here, the elastomer B having the polar group B and the elastomer C compatible with the elastomer B are used. As the elastomer B, maleic anhydride-modified styrene thermoplastic elastomer was used, and as the elastomer C, styrene-butadiene rubber was used.

  With this configuration, the elastomers B and C can be involved in the PTC characteristics, and the polar group B concentration of the elastomer B can be adjusted to adjust the reactivity with the crystalline resin.

  Next, a fifth embodiment will be described. Polar group A and polar group B, epoxy group and carboxyl group, epoxy group and maleic anhydride group, epoxy group and ester group, epoxy group and amino group, or amide group, epoxy group and hydroxyl group, epoxy group and oxazoline group, Any combination of an oxazoline group and a carboxyl group, an oxazoline group and a maleic anhydride group, or an oxazoline group and an ester group was used.

  Examples of the resin having a polar group having reactivity include epoxy group-containing resins such as Bond First 2C (manufactured by Sumitomo Chemical Co., Ltd.) and Epofriend AT501 (manufactured by Daicel Chemical Industries, Ltd.), Nucrel N1525 (Mitsui DuPont Polychemical ( Carboxylic acid group-containing resin, Epocross RPS1005 (manufactured by Nippon Shokubai Co., Ltd.), oxazoline group-containing resin, Modic APM545 (manufactured by Mitsubishi Chemical Corporation) and Bondine LX4110 (manufactured by Atofina Japan Co., Ltd.) There are maleic anhydride group-containing resins, etc., which have the property of molecularly bonding (crosslinking) with other polar group-containing resins.

  With this configuration, it is possible to provide a practical combination of polar groups A and B that is highly reactive and can realize a crosslinked structure.

  Next, a sixth embodiment will be described. As the resin A or the resin B, an epoxy group-containing resin, a carboxyl group-containing resin, an ethylene / vinyl acetate copolymer saponified product, a hydroxyl group-containing resin, a maleic anhydride group-containing resin, or polyethylene glycol is used alone or in combination. With this configuration, it is possible to provide a highly reactive and practical resin A and resin B.

  Next, a seventh embodiment will be described. As the resin C, polyethylene, ethylene / vinyl acetate copolymer, methacrylic resin, or polypropylene is used alone or in combination. With this configuration, PTC characteristics corresponding to various temperature regions of not only the resin A but also the resin C can be imparted. The resin A into which the polar group A has been introduced has many polyethylene bases, has a melting point of about 50 to 110 ° C., and the degree of temperature control by the PTC characteristic is considered to be about 20 to 30 ° C. lower than the melting point. And a control temperature of about 30 to 90 ° C. Resin C is used to achieve a control temperature of about 90 ° C. or higher. For example, when high-density polyethylene is used, 100 to 110 ° C., ethylene / vinyl acetate copolymer is 120 to 150 ° C., methacrylic resin has a melting point similar to that of resin A but gives flexibility, and polypropylene has about 130 ° C. The control temperature can be set to ˜150 ° C.

  Next, an eighth embodiment will be described. As the elastomer B, maleic anhydride group-modified styrene thermoplastic elastomer, epoxy group modified styrene thermoplastic elastomer, polyamide thermoplastic elastomer, polyester thermoplastic elastomer, polyester copolymer, phenol modified acrylonitrile / butadiene rubber alone, Or they can be used in combination.

  With this configuration, a practical elastomer B having flexibility can be provided.

  Next, a ninth embodiment will be described. As the elastomer A or elastomer C, ethylene / propylene rubber, styrene / butadiene rubber, butadiene rubber, or butyl rubber is used alone or in combination.

  With this configuration, it is possible to provide an elastomer that is practical, has high repetitive stability of PTC characteristics, and is easily formed into an ink.

In the seating feeling when the heating element using the polymer resistor ink of the present invention is actually mounted on the car seat, an evaluation equivalent to the current nonwoven fabric / linear type seat heater is obtained, and there is no problem. confirmed. The seating feeling as a seat heater is related to flexibility, stretchability, and cushioning properties, but all of them are satisfied.

  As described above, the polymer resistor ink of the present invention can be applied to heating elements that require flexibility, stretchability and high reliability, such as car seat heaters, handle heaters, curtain heaters, and wearable heaters.

(A) Partially cutaway plan view showing the configuration of the heating element in the first embodiment of the present invention (b) Cross-sectional view of the heating element at the XY position Image of polymer resistor of the present invention (A) Partially cutaway plan view showing the configuration of a conventional heating element (b) Cross-sectional view of the heating element at the XY position

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Heating body 2 Base nonwoven fabric 5 Barrier base film 8 Electrode 9 Polymer resistor 10 Barrier cover film 13 Cover nonwoven fabric 14 Elastomer part 15 Crystalline resin part 16 Reaction product

Claims (3)

Electrically and conductive particles, the crystalline resin and a polymer resistive ink having an elastomer having a maleic anhydride group, and a solvent for dissolving the crystalline resin and the elastomer having an epoxy group. The polymer resistor ink according to claim 1 , further comprising an elastomer C that is compatible with the elastomer having a maleic anhydride group . As an elastomer C, ethylene-propylene rubber, styrene-butadiene rubber, butadiene rubber, butyl rubber alone or in combination made and used according to claim 1 or the polymer resistor ink according to claim 2,.