WO2024195490A1 - Élément chauffant plan - Google Patents

Élément chauffant plan Download PDF

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Publication number
WO2024195490A1
WO2024195490A1 PCT/JP2024/007963 JP2024007963W WO2024195490A1 WO 2024195490 A1 WO2024195490 A1 WO 2024195490A1 JP 2024007963 W JP2024007963 W JP 2024007963W WO 2024195490 A1 WO2024195490 A1 WO 2024195490A1
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Prior art keywords
wax
heating element
ptc resistor
conductive particles
mass
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PCT/JP2024/007963
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English (en)
Japanese (ja)
Inventor
真志 梶
大 宮原
洋徳 伊藤
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東京コスモス電機株式会社
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Publication of WO2024195490A1 publication Critical patent/WO2024195490A1/fr

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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B3/00—Ohmic-resistance heating
    • H05B3/10—Heating elements characterised by the composition or nature of the materials or by the arrangement of the conductor
    • H05B3/12—Heating elements characterised by the composition or nature of the materials or by the arrangement of the conductor characterised by the composition or nature of the conductive material
    • H05B3/14—Heating elements characterised by the composition or nature of the materials or by the arrangement of the conductor characterised by the composition or nature of the conductive material the material being non-metallic
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B3/00—Ohmic-resistance heating
    • H05B3/20—Heating elements having extended surface area substantially in a two-dimensional plane, e.g. plate-heater

Definitions

  • This disclosure relates to a planar heating element.
  • heaters are often installed on the rear of the mirror. These heaters often use planar heating elements with PTC characteristics (positive temperature coefficient), which does not require expensive temperature control devices.
  • a sheet heating element having PTC characteristics usually has a pair of electrodes and a resistor having PTC characteristics (also referred to as a "PTC resistor" in this specification) arranged between the electrodes.
  • a resistor containing a crystalline resin and conductive particles is known as a PTC resistor (for example, Patent Document 1).
  • PTC resistor for example, Patent Document 1
  • the temperature of the sheet heating element (PTC resistor) rises, the crystalline resin contained therein thermally expands, the distance between the conductive particles increases, and the resistance value rises. Then, the resistance value rises sharply near the softening temperature or melting point of the crystalline resin, making it difficult for electricity to conduct.
  • the temperature of the sheet heating element is controlled so that it does not rise above a certain level.
  • the present disclosure therefore aims to provide a sheet heating element whose resistance value is likely to increase in a short time after reaching a certain temperature, and whose resistance value is high after the temperature is increased.
  • One embodiment of the present disclosure provides a planar heating element having a substrate, a pair of electrodes disposed on the substrate, and a PTC resistor disposed on the substrate and between the pair of electrodes, the PTC resistor including conductive particles, a binder resin, and a wax, the wax including a naturally occurring wax and/or a polyolefin-based wax in which the number of melting peaks observed is one or two in a DSC curve obtained by heating from 25°C to 150°C at a heating rate of 10°C/min using a differential scanning calorimeter.
  • a planar heating element can be obtained whose resistance value increases easily in a short time after reaching a certain temperature, and whose resistance value after heating is high.
  • FIG. 1 is a plan view showing an example of the structure of a sheet heating element according to the present disclosure.
  • FIG. 2A is a DSC curve of the polyolefin wax used in Examples A-1 and A-2
  • FIG. 2B is a DSC curve of the ultra-high molecular weight polyethylene used in Comparative Examples A-2 and A-3.
  • a numerical range indicated with “ ⁇ ” means a numerical range including the numbers written before and after " ⁇ ".
  • the sheet heating element 100 has a substrate 1, a pair of electrodes 21, 22 arranged on the substrate 1, and a PTC resistor 3 arranged between the pair of electrodes 21, 22.
  • the configuration of the sheet heating element 100 is not limited to this configuration, and may, for example, have a conductive coating (not shown) arranged on the electrode 2.
  • the substrate 1 is not particularly limited as long as it is insulating and can be laminated with the electrodes 21, 22 and the PTC resistor 3, and is appropriately selected depending on the application of the sheet heating element 100.
  • Specific examples of the substrate 1 include resin films, such as polyester films.
  • the pair of electrodes 21, 22 can have a structure including main electrodes 21a, 22a and comb-shaped electrodes 21b, 22b.
  • the electrodes 21, 22 may be made of any material that can conduct electricity.
  • the electrodes 21, 22 are usually made of metal, and may be made of aluminum, for example.
  • the method for producing the electrodes 21 and 22 is not particularly limited.
  • aluminum foil formed in a pattern may be attached to the substrate 1, or a metal layer disposed on the substrate 1 may be patterned by cutting it out with a blade or the like.
  • the thickness of the PTC resistor 3 in such a sheet heating element 100 is preferably 10 ⁇ m or more, and more preferably 20 to 80 ⁇ m. If the thickness of the PTC resistor 3 is 10 ⁇ m or more, a sufficient amount of heat can be generated. On the other hand, if the thickness is 80 ⁇ m or less, the thickness of the sheet heating element 100 becomes thin, making it easier to apply to various uses.
  • the PTC resistor 3 will be described in detail later.
  • terminals 4 connected to the electrodes 21 and 22 are placed on the substrate 1, and the terminals 4 are connected to external electrodes. Then, by applying a voltage between the electrodes 21 and 22, the temperature of the PTC resistor 3 can be raised to a desired temperature.
  • the sheet heating element 100 can be used for a wide variety of purposes, such as heaters for defogging door mirrors of automobiles, heaters for defogging cameras in automobile rear-end collision prevention devices, heaters for defogging millimeter wave radars in automobile rear-end collision prevention devices, antenna covers, thermistors, heaters for preventing freezing of pipelines, floor heating, heated seats for chairs, heated seats for handrails, etc.
  • the PTC resistor 3 of the sheet heating element 100 will be described in detail below.
  • the PTC resistor of the conventional sheet heating element As described above, in the PTC resistor of the conventional sheet heating element, the PTC characteristics are given mainly by utilizing the thermal expansion and recrystallization of the crystalline resin. However, in this method, the degree of increase in the resistance value after reaching a certain temperature is low, and the degree of increase in the resistance value is also small.
  • the PTC resistor 3 of the sheet heating element 100 of the present disclosure contains a specific polyolefin wax or a natural wax together with the conductive particles and the binder resin. In the PTC resistor 3, these waxes melt near their melting points when the temperature rises. The volume increase due to the melting of these waxes is much larger than the volume increase of general resins. In addition, since they melt easily, the resistance value increases significantly in a short time. Therefore, the sheet heating element of the present disclosure has a larger change in resistance value at a desired temperature and a higher resistance value after heating than the conventional sheet heating element.
  • the PTC resistor of the first aspect comprises a polyolefin wax which, when a differential scanning calorimeter (hereinafter also referred to as "DSC") is used to create a DSC curve by heating from 25°C to 150°C at a heating rate of 10°C/min, shows one or two melting peaks in the DSC curve, a binder resin, and conductive particles.
  • DSC differential scanning calorimeter
  • polyolefin wax refers to an organic material that is solid or semi-solid at room temperature and melts without decomposition when heated.
  • polyolefin wax refers to a wax containing 50% by mass or more of an olefin-derived component.
  • the polyolefin wax used in this embodiment has one or two melting peaks observed in the DSC curve when heated from 25°C to 150°C at a heating rate of 10°C/min in DSC. It is more preferable that the melting peak observed is one.
  • the melting peak in the DSC curve refers to an endothermic peak whose absolute value of the peak height is 0.5 mW or more, and does not include noise whose height is less than 0.5 mW. Note that all DSC curves in this specification are values obtained using 5 mg of sample.
  • the peak height is a value obtained as follows. First, in the DSC curve, the falling position of the line and the rising position of the line in the downward convex region (region where endothermic reaction occurs) are confirmed. If both of these can be confirmed, they are connected with a line, and this is used as the baseline. In this specification, the baseline is drawn only for the large mountain region where the rising and falling exceeds 1 mW. For example, as shown in FIG. 2B, if one large mountain region (region with a downward convexity) contains small peaks (B, C, and D) with a rising or falling of 1 mW or less, only one baseline is drawn for the large mountain region. Also, as shown in FIG.
  • the melting peak in the DSC curve of the polyolefin wax is preferably in the range of 80°C to 150°C, more preferably in the range of 90°C to 140°C, and even more preferably in the range of 100°C to 130°C. This results in a PTC resistor that shows an increase in resistance value at 80°C to 150°C.
  • the weight average molecular weight of the above-mentioned polyolefin wax examples is preferably 1,000 or more and 1,500,000 or less, and more preferably 3,000 or more and 20,000 or less. When the weight average molecular weight of the polyolefin wax is within this range, it is likely to have a melting peak in the above temperature range.
  • the above weight average molecular weight is a polystyrene-equivalent value measured by gel permeation chromatography (GPC).
  • the PTC resistor may contain only one type of the polyolefin wax, or may contain two or more types.
  • polyolefin waxes include homopolymers of olefins, copolymers of two or more types of olefins, copolymers of olefins and monomers other than olefins, etc.
  • More specific examples of polyolefin waxes include polyethylene waxes such as low-density polyethylene wax, medium-density polyethylene wax, and high-density polyethylene wax, polypropylene wax, polybutene wax, ethylene-propylene copolymer wax, and ethylene-propylene-butene copolymer wax.
  • these may be oxidized polyolefin waxes obtained by oxidizing them by a known method.
  • polyethylene waxes are preferred from the viewpoints of availability and PTC characteristics, etc.
  • the amount of polyolefin wax in the PTC resistor is preferably 6% by mass or more and 24% by mass or less, and more preferably 12% by mass or more and 20% by mass or less. If the amount of polyolefin wax in the PTC resistor is 6% by mass or more, the PTC multiplier of the PTC resistor is further increased, and the rate of increase in the resistance value after the PTC resistor heats up and reaches a certain temperature is likely to be further increased. On the other hand, if it is 24% by mass or less, the amount of conductive particles becomes sufficiently large in comparison, and the PTC characteristics are likely to be further improved.
  • Binder resin may be any resin capable of binding the polyolefin wax and the conductive particles described below, or binding them to a substrate, etc., but it is preferable that the binder resin does not prevent the volume change caused by melting the polyolefin wax.
  • the binder resin itself may expand with increasing temperature, and contribute to increasing the resistance value of the PTC resistor.
  • the PTC resistor may contain only one type of binder resin, or may contain two or more types.
  • binder resin examples include known thermoplastic resins. Specific examples include thermoplastic polyurethane resin, polyester resin, polyacrylate resin, polysiloxane resin, vinyl halide resin, vinylidene resin, polyimide resin, phenoxy resin, polyether resin, polyketone resin, polyvinyl butyral resin, polyvinylpyrrolidone resin, polyacrylate resin, SEBS resin (styrene-ethylene-butylene-styrene copolymer) and its hydrogenated products, SEPS resin (styrene-ethylene-propylene-styrene copolymer) and its hydrogenated products, etc. Among these, SEBS resin and hydrogenated SEPS resin are preferred from the viewpoint of being easily deformable and not hindering the volume change of the above-mentioned polyolefin wax.
  • the amount of binder resin in the PTC resistor is preferably 6 to 30% by mass, more preferably 15 to 28% by mass.
  • the amount of binder resin in the PTC resistor is 6% by mass or more, it becomes easier to print conductive resin, polyolefin wax, and compositions containing the binder resin, and the fixation after printing becomes good. Furthermore, the strength of the PTC resistor is also likely to be further increased.
  • the amount of binder resin is 30% by mass or less, the amount of conductive particles becomes relatively large enough, and the PTC characteristics tend to be further improved.
  • the conductive particles are not particularly limited as long as they are conductive particles, but particles having a thermal expansion coefficient of 20 ⁇ 10 ⁇ 6 /° C. or less are preferred, and particles having a thermal expansion coefficient of 6.0 ⁇ 10 ⁇ 6 /° C. or less are more preferred.
  • the thermal expansion coefficient of the conductive particles can be determined from the material of the conductive particles.
  • the PTC resistor may contain only one type of conductive particles, or may contain two or more types.
  • Examples of conductive particles include carbon-based particles such as graphite, carbon black, carbon nanotubes, and graphene; metal-based particles such as nickel powder, copper powder, silver powder, and tungsten powder; and the like.
  • carbon-based particles such as graphite, carbon black, carbon nanotubes, and graphene
  • metal-based particles such as nickel powder, copper powder, silver powder, and tungsten powder
  • nickel powder, silver powder, tungsten powder, and graphite are preferred because they have a high affinity with the above-mentioned polyolefin wax and binder resin, and are less likely to precipitate in the composition for producing the PTC resistor.
  • the shape of the conductive particles is not particularly limited, and may be, for example, spherical, amorphous, tubular, rod-like, flat, crushed, etc.
  • the specific surface area of the conductive particles is preferably 5 m 2 /g or less. The specific surface area is a value measured by a gas adsorption method.
  • the size of the conductive particles is appropriately selected depending on the type of conductive particles, etc.
  • the average particle diameter is preferably 30 ⁇ m or less, and more preferably 1 ⁇ m or more and 10 ⁇ m or less. If the average particle diameter is 30 ⁇ m or less, the PTC magnification of the PTC resistor tends to be better.
  • the average particle diameter is a value measured by the laser diffraction/scattering method, and is the median (D50) in the cumulative particle size distribution.
  • the content of conductive particles in the PTC resistor is preferably 45% by mass or more and 80% by mass or less, more preferably 50% by mass or more and 70% by mass or less, and even more preferably 55% by mass or more and 67.5% by mass or less.
  • the amount of conductive particles in the PTC resistor is 45% by mass or more, the PTC characteristics tend to be more stable.
  • the amount of conductive particles in the PTC resistor is 80% by mass or less, the amount of the polyolefin wax and binder resin increases, and the resistance value when heated tends to increase.
  • the PTC resistor may contain other components as necessary within the scope of the purpose and effect of the present embodiment.
  • other components include various additives such as antioxidants and flame retardants.
  • the PTC resistor of this embodiment can be manufactured by applying a composition containing the polyolefin wax, the binder resin, the conductive particles, and optionally a solvent, and heating and curing the composition.
  • the type of solvent is not particularly limited as long as it is capable of uniformly dissolving or dispersing the polyolefin wax, binder resin, conductive particles, etc. described above.
  • the boiling point of the solvent is preferably 100°C or higher, more preferably 100 to 330°C, and even more preferably 150 to 250°C. If the boiling point of the solvent is within this range, the storage stability of the composition is improved, and the composition is also easier to apply.
  • the solvent is appropriately selected according to the type of polyolefin wax and the type of binder resin.
  • examples include alcohols, ketones, esters, glycol esters, glycol ethers, ethers, aromatic hydrocarbons, and mixtures thereof, with terpineol, butyl carbitol acetate, tetralin, toluene, and mixtures thereof being preferred.
  • the amount of the solvent is appropriately selected according to the viscosity of the desired composition, but is usually preferably about 20 to 70 parts by mass, and more preferably 25 to 65 parts by mass, per 100 parts by mass of the total amount of the composition (ink). If the amount of the solvent is within this range, the viscosity of the composition (ink) tends to fall within the desired range.
  • the preferred viscosity of the composition is appropriately selected depending on the method for forming the PTC resistor.
  • the viscosity of the composition is preferably 100 to 400 dPa ⁇ s. This viscosity is measured at 25°C using a cylindrical rotational viscometer (manufactured by Rion Co., Ltd.).
  • the viscosity of the composition is within this range, the composition can be applied to the desired thickness and can form a film without unevenness.
  • the method for preparing the above composition is not particularly limited, and the polyolefin wax, resin binder, conductive particles, and solvent may be mixed at once. Alternatively, the resin binder and solvent may be mixed first, and then the polyolefin wax and conductive particles may be mixed.
  • the method for applying the composition is not particularly limited, and examples include screen printing, roll coating, and application with a dispenser.
  • the composition can be cured by heating it to about 100 to 200°C.
  • the heating time is preferably about 1 to 30 minutes.
  • the PTC resistor of the second aspect includes a naturally occurring wax, a binder resin, and conductive particles. Each component will be described below.
  • Naturally derived wax refers to an organic material that is solid or semi-solid at room temperature (25°C) and melts without decomposition when heated.
  • Naturally derived wax refers to a plant-based wax derived from a plant or an animal-based wax derived from an animal.
  • a plant-based wax refers to a wax made from a plant.
  • An animal-based wax refers to a wax derived from an animal.
  • a PTC resistor may contain only one type of naturally derived wax, or may contain two or more types.
  • the type of naturally derived wax contained in a PTC resistor is not particularly limited, but a resistance value increase at 40°C or higher and 100°C or lower is usually required for a PTC resistor. Therefore, the melting point of the naturally derived wax is preferably 40°C or higher and 100°C or lower, more preferably 50°C or higher and 90°C or higher.
  • the wax ester component contained in the naturally derived wax is preferably 10% by mass or more. If the wax ester component is 10% by mass or more, the melting point of the naturally derived wax is likely to fall within the above range. In addition, melting near the melting point is likely to proceed in a shorter period of time.
  • the wax ester component refers to an ester in which a higher fatty acid and a higher monohydric alcohol are bonded in a one-to-one ratio.
  • the wax ester component is, for example, an ester of a higher fatty acid having 10 to 50 carbon atoms and a higher monohydric alcohol having 10 to 50 carbon atoms.
  • the total number of carbon atoms constituting the wax ester component is preferably 20 to 100, and more preferably 30 to 50.
  • the naturally derived wax may further contain free saturated fatty acids (the above-mentioned higher fatty acids) and free alcohols (the above-mentioned higher monohydric alcohols).
  • the amount of free saturated fatty acids is preferably 20% by mass or less relative to the total mass of the naturally derived wax.
  • the amount of free alcohol is more preferably 15% by mass or less relative to the total mass of the naturally derived wax.
  • the iodine value of the naturally derived wax is preferably 80 or less, more preferably 30 or less, and even more preferably 25 or less.
  • the iodine value represents the amount of unsaturated bonds in the hydrocarbon chains of the components contained in the naturally derived wax. It is preferable that the iodine value in the naturally derived wax, i.e., the amount of unsaturated double bonds, is small. If the amount of unsaturated double bonds is large, the naturally derived wax is less likely to melt even when the temperature of the PTC resistor rises. In other words, if the iodine value exceeds 80, the resistance value is less likely to increase when the temperature rises. In contrast, if the iodine value is 80 or less, the naturally derived wax is more likely to melt when the temperature of the PTC resistor rises, and the resistance value is more likely to increase.
  • plant-based waxes which are a type of naturally derived wax, include candelilla wax, carnauba wax, rice wax, Japan wax wax, hydrogenated jojoba wax, etc.
  • carnauba wax, candelilla wax, and rice wax are preferred from the viewpoints of ease of availability and ease of increasing the PTC multiplier.
  • examples of animal-based waxes which are a type of naturally derived wax, include beeswax and lanolin wax.
  • the amount of naturally occurring wax in the PTC resistor is preferably 5% by mass or more and 50% by mass or less, and more preferably 7% by mass or more and 40% by mass or less.
  • the amount of naturally occurring wax in the PTC resistor is 5% by mass or more, the resistance value of the PTC resistor when the temperature rises is more likely to increase.
  • it is 50% by mass or less the amount of conductive particles described below becomes relatively large enough, and the PTC characteristics of the PTC resistor are more likely to be improved.
  • Binder resin may be any resin capable of binding the above-mentioned naturally occurring wax and the conductive particles described below, or binding them to a substrate or the like, but it is preferable that the binder resin does not prevent the volume change caused by melting of the above-mentioned naturally occurring wax.
  • the binder resin itself may expand with increasing temperature, and contribute to an increase in the resistance value of the PTC resistor.
  • the PTC resistor may contain only one type of binder resin, or may contain two or more types.
  • the binder resin is the same as the binder resin of the PTC resistor of the first embodiment.
  • the amount of binder resin in the PTC resistor of this embodiment is preferably 5% by mass or more and 50% by mass or less, and more preferably 10% by mass or more and 40% by mass or less.
  • the amount of binder resin in the PTC resistor is 5% by mass or more, it becomes easier to print conductive resin, naturally derived wax, and compositions containing the binder resin, and the fixing property after printing becomes good. Furthermore, the strength of the PTC resistor is also likely to be further increased.
  • the amount of binder resin is 50% by mass or less, the amount of conductive particles becomes sufficiently large relatively, and the PTC characteristics are likely to be further improved.
  • Conductive Particles are not particularly limited as long as they are particles having electrical conductivity, and are the same as the conductive particles of the PTC resistor of the first embodiment described above.
  • the content of conductive particles in the PTC resistor of this embodiment is preferably 45% by mass or more and 80% by mass or less, and more preferably 50% by mass or more and 70% by mass or less.
  • the amount of conductive particles in the PTC resistor is 45% by mass or more, the PTC characteristics tend to be more stable.
  • the amount of conductive particles in the PTC resistor is 80% by mass or less, the amount of the naturally derived wax and binder resin increases, and the resistance value when heated tends to increase.
  • the PTC resistor may contain other components as necessary within the scope of the purpose and effect of the present embodiment.
  • other components include various additives such as antioxidants and flame retardants.
  • the PTC resistor of this embodiment can be manufactured by applying a composition containing the naturally occurring wax, the binder resin, the conductive particles, and, if necessary, a solvent, and heating and curing the composition.
  • the type of solvent is not particularly limited as long as it is capable of uniformly dissolving or dispersing the above-mentioned naturally derived wax, binder resin, conductive particles, etc.
  • the boiling point of the solvent is preferably 100°C or higher, more preferably 100 to 330°C, and even more preferably 150 to 250°C. If the boiling point of the solvent is within this range, the storage stability of the composition is improved, and the composition is also easier to apply.
  • the solvent is appropriately selected according to the type of naturally occurring wax and the type of binder resin.
  • examples include alcohols, ketones, esters, glycol esters, glycol ethers, ethers, aromatic hydrocarbons, and mixtures thereof, with terpineol, butyl carbitol acetate, tetralin, toluene, and mixtures thereof being preferred.
  • the amount of the solvent is appropriately selected according to the viscosity of the desired composition (ink), but typically, it is preferably about 40 to 90 parts by mass, and more preferably 40 to 85 parts by mass, per 100 parts by mass of the total amount of the composition (ink). If the amount of the solvent is within this range, the viscosity of the composition is likely to fall within the desired range.
  • the preferred viscosity of the composition is appropriately selected depending on the method for forming the PTC resistor.
  • the viscosity of the composition is preferably 100 to 400 dPa ⁇ s. This viscosity is measured at 25°C using a cylindrical rotational viscometer (manufactured by Rion Co., Ltd.).
  • the viscosity of the composition is within this range, the composition can be applied to the desired thickness and can form a film without unevenness.
  • the method for preparing the above composition is not particularly limited, and the naturally derived wax, resin binder, conductive particles, and solvent may be mixed at once. Alternatively, the resin binder and solvent may be mixed first, and then the naturally derived wax and conductive particles may be mixed.
  • the method for applying the composition is not particularly limited, and examples include screen printing, roll coating, and application with a dispenser.
  • the composition can be cured by heating it to about 100 to 200°C.
  • the heating time is preferably about 1 to 30 minutes.
  • Polyolefin-based component Polyethylene wax (CERAFLOUR 961 manufactured by BYK) - Ultra-high molecular weight polyethylene (Mipelon PM-200, manufactured by Mitsui Chemicals)
  • Binder resin SEBS resin (styrene-ethylene-butylene-styrene block copolymer, Tuftec 1913, manufactured by Asahi Kasei Corporation) - Hydrogenated SEPS resin (hydrogenated styrene-ethylene-propylene-styrene block copolymer, Septon 2002, Kuraray Co., Ltd.)
  • a DSC curve was obtained for the polyolefin component in the range of 25°C to 150°C at a heating rate of 10°C/min using DSC. The number of melting peaks and the absolute value of the melting peak heights were determined. These results are shown in Table 1. Furthermore, the DSC curves for the polyethylene wax used in Examples A-1 and A-2 are shown in Figure 2A, and the DSC curves for the ultra-high molecular weight polyethylene used in Comparative Examples A-2 and A-3 are shown in Figure 2B.
  • the average particle diameter D50 of the conductive particles was measured by a laser diffraction/scattering method.
  • the thermal expansion coefficient was taken as a literature value.
  • the specific surface area was measured by a gas adsorption method.
  • PTC resistor was prepared according to the following procedure.
  • Example A-1 A varnish was prepared by mixing 8.0 parts by mass of hydrogenated SEPS resin and 51.0 parts by mass of an organic solvent (terpineol) with a stirrer at 100° C. for 1 hour. The varnish was mixed with 9.0 parts by mass of a polyolefin wax (polyethylene wax) and 32.0 parts by mass of conductive particles (spherical carbon) and crushed with a crusher to obtain the desired screen printing ink.
  • a substrate having a pair of comb electrodes was prepared, and the ink was printed between the comb electrodes by screen printing. The substrate was then heated to 150° C. to produce a sheet heating element having a desired PTC resistor.
  • Example A-1 A sheet heating element having a PTC resistor was produced in the same manner as in Example A-1, except that a paste was produced with the composition shown in Table 1 without using any polyolefin wax.
  • Example A-2 and Comparative Examples A-2 and A-3
  • a sheet heating element having a PTC resistor was produced in the same manner as in Example A-1, except that the organic solvent and the type and amount of each component were changed as shown in Table 1.
  • the sheet heating element was heated in a room temperature environment (25° C.), and the temperature when the temperature stabilized and the time required to reach the temperature were determined. Then, the temperature was determined by the following formula. (Stable temperature - initial temperature) / (time to stabilization)
  • the resistance value of each sheet heating element was measured when the temperature was raised from -40°C to 120°C. The maximum resistance value and the minimum resistance value were then identified, and the ratio between them (maximum resistance value/minimum resistance value) was calculated as the maximum PTC magnification. The measurement of each resistance value was performed by the two-terminal method or the four-terminal method.
  • the resistance value of the sheet heating element immediately after production was measured at 25° C. Next, the temperature of the sheet heating element was changed from ⁇ 40° C. to 120° C., and then returned to 25° C., and the resistance value was measured again. The ratio of these values (resistance value at 25° C. after temperature change/resistance value at 25° C. before temperature change) was calculated as the maximum PTC magnification in a room temperature environment.
  • Carnauba wax melting point 80°C to 86°C, iodine value 5 to 14, wax ester content 80 to 85% by mass
  • Candelilla wax melting point 68°C to 73°C, iodine value 5 to 14, wax ester content 80 to 85% by mass
  • Rice wax melting point 80°C, iodine value 7.4, wax ester content 93-97% by mass
  • Conductive particles artificial graphite, average particle size D50 4 ⁇ m, specific surface area 5.0 m 2 /g, thermal expansion coefficient 6.0 ⁇ 10 ⁇ 6 /° C.
  • Binder resin SEBS resin (styrene-ethylene-butylene-styrene block copolymer, Tuftec 1913, manufactured by Asahi Kasei Corporation)
  • Solvent Terpineol
  • Sheet heating elements including each PTC resistor were prepared by the following procedure.
  • Example B-1 A varnish was prepared by mixing 4.9 parts by mass of SEBS resin and 63.5 parts by mass of an organic solvent (terpineol) with a stirrer at 100° C. for 1 hour. The varnish was mixed with 11.5 parts by mass of a natural wax (carnauba wax) and 20.1 parts by mass of conductive particles (artificial graphite) and crushed with a crusher to obtain an ink for screen printing.
  • a substrate having a pair of comb electrodes was prepared, and the ink was printed between the comb electrodes by screen printing. The substrate was then heated to 150° C. to produce a sheet heating element having a desired PTC resistor.
  • Example B-2 A sheet heating element having a PTC resistor was produced in the same manner as in Example B-1, except that the type of naturally occurring wax was changed to candelilla wax.
  • Example B-3 A sheet heating element having a PTC resistor was produced in the same manner as in Example B-1, except that the type of naturally occurring wax was changed to rice wax.
  • Example B-1 A sheet heating element having a PTC resistor was produced in the same manner as in Example B-1, except that castor oil was used instead of the naturally occurring wax.
  • the resistance values of the sheet heating elements produced in Examples B-1 to B-3 and Comparative Example B-1 were measured from 25°C to 120°C.
  • the maximum PTC magnification was calculated as (maximum resistance value)/(resistance value at 25°C).
  • the resistance values were measured using the two-terminal method or the four-terminal method. The results are shown in Table 2.
  • the maximum PTC magnification was judged as ⁇ when it was 100 times or more, ⁇ when it was 2 times or more and less than 100 times, and ⁇ when it was less than 2 times.
  • the PTC resistor of the present disclosure is easy to increase in resistance in a short time after reaching a certain temperature, and has a high resistance after the temperature is increased, so that it is very useful for manufacturing various sheet heating elements.

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  • Thermistors And Varistors (AREA)

Abstract

La présente invention aborde le problème de la fourniture d'un élément chauffant plan dont la valeur de résistance est facilement augmentée en un court laps de temps après avoir atteint une certaine température et qui a une valeur de résistance élevée après une augmentation de température. L'élément chauffant plan comprend : un substrat ; une paire d'électrodes disposées sur le substrat ; et une résistance PTC disposée sur le substrat et entre la paire d'électrodes. La résistance PTC contient des particules conductrices, une résine liante et une cire. La cire comprend une cire naturelle, et/ou une cire à base de polyoléfine dans laquelle le nombre de pics de fusion est de 1 ou 2 tel qu'observé dans une courbe DSC obtenue par élévation de la température de 25°C à 150°C à une vitesse d'élévation de température de 10°C/min à l'aide d'un calorimètre à balayage différentiel.
PCT/JP2024/007963 2023-03-23 2024-03-04 Élément chauffant plan WO2024195490A1 (fr)

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JP2023-046590 2023-03-23

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0669001A (ja) * 1992-08-21 1994-03-11 Sekisui Plastics Co Ltd 正特性サーミスタ
JP2000200704A (ja) * 1998-11-02 2000-07-18 Tdk Corp 有機質正特性サ―ミスタ
JP2002313541A (ja) * 2001-04-09 2002-10-25 Honny Chem Ind Co Ltd ヒューズ機能を有するｐｔｃ面状発熱体
JP2003243206A (ja) * 2002-02-21 2003-08-29 Tsutsumi Eng:Kk エステル化合物を利用したｐｔｃ材料
JP2017535964A (ja) * 2014-11-17 2017-11-30 ヘンケル・アクチェンゲゼルシャフト・ウント・コムパニー・コマンディットゲゼルシャフト・アウフ・アクチェンＨｅｎｋｅｌ ＡＧ ＆ Ｃｏ． ＫＧａＡ 正の温度係数組成物

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0669001A (ja) * 1992-08-21 1994-03-11 Sekisui Plastics Co Ltd 正特性サーミスタ
JP2000200704A (ja) * 1998-11-02 2000-07-18 Tdk Corp 有機質正特性サ―ミスタ
JP2002313541A (ja) * 2001-04-09 2002-10-25 Honny Chem Ind Co Ltd ヒューズ機能を有するｐｔｃ面状発熱体
JP2003243206A (ja) * 2002-02-21 2003-08-29 Tsutsumi Eng:Kk エステル化合物を利用したｐｔｃ材料
JP2017535964A (ja) * 2014-11-17 2017-11-30 ヘンケル・アクチェンゲゼルシャフト・ウント・コムパニー・コマンディットゲゼルシャフト・アウフ・アクチェンＨｅｎｋｅｌ ＡＧ ＆ Ｃｏ． ＫＧａＡ 正の温度係数組成物

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