JP2010073499A - Heater element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heater element of a self-temperature control type having a higher heat resistance and performing heating of a heated object efficiently. <P>SOLUTION: The heater element 100 includes at least two conductors 1A, 1B, a PTC member 5 arranged to contact with each of the two conductors 1A, 1B, and the PTC member 5 contains conductive particles and porous ceramic particles dispersed in resin. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a heater element, and more particularly to a self-temperature control type heater element.

  The heater element is a floor heating device that warms the floor, a snow melting device that warms and melts snow on roads and roofs, an anti-fogging device that prevents fogging by warming a mirror, or a device that warms plant piping to a constant temperature. Etc. are used. As such a heater element, a heating wire heater is used in which a conductor generates heat by a current flowing through the conductor. In order to prevent overheating of the heater element, a thermostat or a temperature fuse that controls the temperature of the heater element may be attached to the heating wire heater.

In recent years, instead of a heating wire heater, PTC (Positive) is used for the purpose of easily controlling the temperature of the heater element without attaching a thermostat or the like to the heating wire heater.
In some cases, a self-temperature control type heater element having a temperature coefficient characteristic is used.

  The following patent document describes an embodiment of a self-temperature control type heater element having such PTC characteristics. This heater element has two parallel conductors and a PTC member provided so as to be in contact with these conductors.

In this PTC member, conductive particles such as carbon black are dispersed in a predetermined amount in the resin. When the heater element is below a predetermined temperature, a large number of conductive paths are formed by contact between the conductive particles in the PTC member, and the resistance of the PTC member is kept low. For this reason, when a voltage is applied between the two conductors of the heater element, a current flows in the PTC member, the temperature of the PTC member rises, and the heater element generates heat. When the temperature of the PTC member rises in this way, the resin in the PTC member expands, and part of the conductive particles separates accordingly. Therefore, a part of the conductive path is cut and the resistance of the PTC member is increased. As a result, the current flowing in the PTC member is reduced and the temperature of the PTC member is lowered. In this way, the self-temperature control of the heater element is performed.
US Pat. No. 4,33,148

  By the way, it is desirable that the heater element has high heat resistance and can efficiently heat an object to be heated. Here, heat resistance means having a long life when a heat aging test is performed on the heater element.

  However, the heater element described in Patent Document 1 has room for improvement in terms of heat resistance.

  Then, this invention is made | formed in view of the said situation, and it aims at providing the heater element which has high heat resistance and can heat a heating target object efficiently.

  The heater element of the present invention includes at least two conductors and a PTC member provided so as to be in contact with each of the two conductors, and the PTC member includes conductive particles and porous particles dispersed in a resin. It contains a ceramic particle.

  According to the heater element having such a configuration, when the heater element is placed in contact with the object to be heated and a voltage is applied between the two conductors, the conductive particles in the PTC member cause a current in the PTC member. Flows and the PTC member generates heat due to the current. At this time, far infrared rays are emitted from the porous ceramic particles in the PTC member. For this reason, the heating object is heated by heat generation of the PTC member itself and by far infrared rays. Therefore, according to the heater element of the present invention, the heating object can be efficiently heated. The reason why this far-infrared ray is emitted is not clear, but the present inventors presume that the ceramic particles are porous. Moreover, the heater element of this invention has high heat resistance because a porous ceramic particle is contained in a PTC member.

  In the present invention, the porous ceramic particles are preferably made of an alumina / silica composite oxide.

  When the porous ceramic particles are made of an alumina / silica composite oxide, far infrared rays are emitted more strongly, so that the heater element can heat the object to be heated more efficiently.

  The heater element according to the present invention has higher heat resistance and can efficiently heat the object to be heated.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to FIG.

  FIG. 1 is a sectional view showing an embodiment of the heater element of the present invention.

  As shown in FIG. 1, the heater element 100 is in contact with two conductors 1A and 1B that are substantially parallel to each other at a predetermined interval, and the conductors 1A and 1B, and covers the outer peripheral surfaces of the conductors 1A and 1B. A PTC member 5 and an insulating layer 10 covering the PTC member 5 are provided.

  The PTC member 5 has a configuration in which conductive particles and porous ceramic particles are dispersed in a resin.

  According to the heater element 100 according to the present embodiment, when a voltage (for example, AC voltage) is applied to the two conductors 1A and 1B in a state where the heater element 100 is installed so as to be in contact with the object to be heated, the PTC member Current flows in the PTC member 5 due to the conductive particles in the PTC member 5, and the PTC member 5 generates heat due to the current. At this time, far infrared rays are emitted from the porous ceramic particles in the PTC member 5. For this reason, the heating object is heated by the heat generated by the PTC member 5 and by far infrared rays. Therefore, according to the heater element 100, the heating object can be efficiently heated. In other words, according to the heater element 100, the amount of heat generated by the PTC member 5 can be kept low by heating with far infrared rays. Therefore, according to the heater element 100, power consumption can be kept low. The reason why this far-infrared ray is emitted is not clear, but the present inventors presume that the ceramic particles are porous. Further, the heater element 100 has high heat resistance because the PTC member 5 contains porous ceramic particles.

  Moreover, according to the heater element 100, even if the heater element 100 and the heating object are separated from each other with a space therebetween, the heating object can be heated by far infrared rays. For example, when the object to be heated is snow, the snow heated by the heater element 100 is melted over time, and as a result, a space may be formed between the snow and the heater element 100. In this case, it is difficult to effectively melt snow after that by only the heat generation of the PTC member 5 itself, but the heater element 100 emits far infrared rays from the porous ceramic particles. For this reason, according to the heater element 100, it is possible to continue snow melting. Therefore, the heater element 100 can sufficiently shorten the time required for melting snow.

  Next, the material of each component of the heater element 100 will be described.

  The resin used for the PTC member 5 is preferably a crystalline resin, and specific examples include a polyolefin resin, a polyamide-based resin, a polyacetal resin, a polyester resin, and a fluorine resin.

  Examples of the polyolefin resin include polyethylenes such as high density polyethylene, medium density polyethylene, low density polyethylene, and linear low density polyethylene, polypropylenes such as isotactic polypropylene and syndiotactic polypropylene, polybutene, and 4-methylpentene. -1 resin and the like. Examples of the polyamide-based resin include nylon 6, nylon 8, nylon 11, nylon 66, nylon 610, and the like. The polyacetal resin may be a homopolymer based on a monomer or a copolymer based on two or more types of monomers. Examples of the polyester resin include polyethylene terephthalate and polybutylene terephthalate. Examples of the fluororesin include polyvinylidene fluoride (PVDF), ethylene-tetrafluoroethylene copolymer (ETFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), polytetrafluoroethylene (PTFE), and the like. be able to. These crystalline resins may be used alone or in a combination of two or more. Among these, polyolefin resin is preferable from the viewpoint of using the heater element 100 for a snow melting device.

Examples of the conductive particles include carbon particles such as carbon black particles and graphite particles, and metals such as iron (Fe), nickel (Ni), platinum (Pt), copper (Cu), silver (Ag), and gold (Au). Particles, tin-added indium oxide (ITO), tin oxide (SnO ₂ ), fluorine-added tin oxide (Fluorine-Tin-Oxide: FTO), antimony-added tin oxide (Antimony-Tin-Oxide: ATO) And conductive metal oxide particles such as zinc oxide (ZnO).

  Among these, carbon-based particles such as carbon black particles and graphite particles are preferable. When metal particles are used as the conductive particles, the PTC member 5 has a sharply high resistance at a specific temperature, and the resistance change tends to be very small at other temperatures. For this reason, if the temperature that is kept constant by the self-temperature control of the heater element 100 is set to be equal to or lower than the temperature at which the resistance sharply increases, self-temperature control may be difficult due to a small resistance change. . In contrast, when carbon-based particles are used as the conductive particles, the overall resistance of the PTC member 5 gradually increases with respect to the temperature rise of the PTC member 5. For this reason, the heater element 100 using carbon-based particles has an advantage that self-temperature control can be easily performed at an arbitrary temperature by adjusting the voltage applied to the conductors 1A and 1B.

  The average particle size of the carbon-based particles is not particularly limited. For example, the average particle size is preferably 30 to 90 nm from the viewpoint of electrical conductivity, and particularly preferably 15 to 60 nm. It is more preferable from the viewpoint of obtaining the resistance of the PTC member 5. The average particle diameter is a value when measured by observation with an electron microscope.

  Further, the content of the conductive particles in the PTC member 5 is not particularly limited, but for example, 3 to 30% by mass is preferable from the viewpoint of obtaining the resistance of the PTC member 5.

Examples of the material for the porous ceramic particles include metal oxides such as silica (SiO ₂ ) alumina (Al ₂ O ₃ ), zirconia (ZrO ₂ ), titania (TiO ₂ ), magnesia (MgO), or a mixture thereof. And zeolite (SiO ₄ · AlO ₄ ), aluminum titanate (Al ₂ TiO ₅ ), zircon (ZrSiO ₄ ), cordierite (2MgO · 2Al ₂ O ₃ · 5SiO ₂ ), spodumene (Li ₂ O · Al ₂ O) _And composite oxides such as 3.4SiO ₂ ). Among them, porous ceramic particles made of an alumina-silica composite oxide containing alumina and silica emit far infrared rays more strongly when the temperature of the PTC member 5 rises, so that the object to be heated can be heated more efficiently. To preferred.

  The average particle diameter of the porous ceramic particles is not particularly limited, but for example, the average particle diameter is preferably 3 to 30 μm from the viewpoint of manufacturing and durability of the PTC member 5, and particularly 5 to 20 μm. It is preferable from the viewpoint of obtaining the resistance of the PTC member 5. The method for measuring the average particle size of the porous ceramic particles is the same as the method for measuring the average particle size of the conductive particles.

  The content of the porous ceramic particles in the PTC member 5 is not particularly limited, but is preferably 10 to 30% by mass, for example, from the viewpoint of emitting far infrared rays.

  The porous ceramic particles preferably emit 3 to 12 μm of far infrared rays from the viewpoint of warming water. When the heater element 100 using the PTC member 5 containing such porous ceramic particles is used in a snow melting device, snow melting can be performed efficiently.

  Each of the conductors 1A and 1B is made of a single wire such as a copper wire plated with nickel or a stranded wire.

  The insulating layer 10 is made of an insulating material. As the insulating material, a resin is preferable, and a flame retardant resin is more preferable.

  Next, a method for manufacturing the heater element 100 will be described.

  First, a resin composition-containing liquid containing at least a resin, conductive particles, and porous ceramic particles is prepared. For example, a crystalline resin is used as the resin. In the preparation, first, conductive particles and porous ceramic particles that have been previously dried are added to the resin, and the mixture is stirred and mixed using a stirring means such as a ball mill. And heat processing is performed with stirring and mixing, and melt kneading is performed. At this time, the temperature of the heat treatment is preferably a temperature equal to or higher than the melting point of the crystalline resin.

  The resin composition thus obtained is extruded around the conductors 1A and 1B so as to come into contact with the conductors 1A and 1B arranged substantially in parallel at a predetermined interval. Then, the resin composition is cooled and solidified to form the PTC member 5. Thereafter, the insulating layer 10 is provided by extrusion so as to cover the PTC member 5. Thus, the heater element 100 is obtained.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to said embodiment. For example, in the above embodiment, the two conductors 1A and 1B are used, but three or more conductors may be used. In the above embodiment, the PTC member 5 is provided so as to contact the conductors 1A and 1B and cover the outer peripheral surfaces of the conductors 1A and 1B, but the PTC member 5 contacts the conductors 1A and 1B. The PTC member 5 is not necessarily provided so as to cover the outer peripheral surfaces of the conductors 1A and 1B. For example, the PTC member 5 may be disposed only between the conductors 1A and 1B.

  Hereinafter, the content of the present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to the following examples.

(Examples 1-4)
A heater element was produced in which two conductors were arranged in a PTC member so as to be spaced apart from each other in parallel.

  As the PTC member, a PTC member in which carbon black particles and porous ceramic particles are dispersed in a crystalline resin was used. Polyolefin was used as the crystalline resin. Carbon black particles having an average particle diameter of 30 nm were used, and the content of carbon black particles in the PTC member was as shown in Table 1 with respect to 100 parts by mass of the crystalline resin. Moreover, as the porous ceramic particles, ceramic powder TWP (trade name) manufactured by Japan TOPY having an average particle diameter of 10 μm is used, and the content of the porous ceramic particles in the PTC member is 100 parts by mass of the crystalline resin. On the other hand, the values shown in Table 1 were used.

(Comparative Example 1)
As the PTC member, a heater element was produced in the same manner as in Example 1 except that the content of the carbon black particles and the porous ceramic particles was set to the values shown in Table 1 with respect to 100 parts by mass of the crystalline resin.

(Power consumption measurement)
For each of Examples and Comparative Example 1, a measurement tube through which a liquid flows was prepared, and 1 m of each heater element of Examples 1 to 4 and Comparative Example 1 was prepared and attached to each measurement tube. Then, the outside is covered with a heat insulating material, a voltage of 200 V is applied to each heater element, the temperature of the liquid flowing in each measuring tube is 10 degrees, and the flow rate of the liquid is adjusted so that the heat generation of the heater element is constant. It was adjusted. And the power consumption per 1 m of heater elements in this case was measured. The results are shown in Table 1. As shown in Table 1, the power consumption of the heater elements of Examples 1 to 4 is smaller than the power consumption of the heater element of Comparative Example 1, and the power consumption is higher for the examples with higher content of porous ceramic particles. Small results were obtained.

(Snow melting rate measurement)
8 m of each heater element was prepared, embedded in concrete, and placed in an environment where the temperature was −5 ° C., and 700 g of snow was placed on the concrete. Then, an AC voltage of 240 V was applied between the two conductors of each heater element for 30 minutes, and the weight of the melted snow was measured. The snow melting rate was calculated as (weight of melted snow) / 700 g × 100. The results are shown in Table 1. As shown in Table 1, it was found that any of Examples 1 to 4 showed a higher snow melting rate than Comparative Example 1.

(Heat resistance measurement)
Each heater element was subjected to a heat aging test to evaluate heat resistance. In the heat aging test, a flat heater element was allowed to stand in a temperature-controlled room at 121 ° C. for 1 hour, and then a cylindrical weight having a weight of 300 g and a diameter of 9 mm was placed on the heater element. The measurement was performed by leaving the sample for 1 hour and measuring the thickness of the portion where the weight of the heater element was placed. The results are shown in Table 1. In Table 1, the heater element where the weight of the heater element is placed is 50% or more of the original thickness, and is indicated as “◯” as having heat resistance, and 75% or more. The heater elements that were indicated by “◎” are indicated as having higher heat resistance. As shown in Table 1, Examples 1 to 4 were found to have higher heat resistance than Comparative Example 1.

  From the above, it was confirmed that the heater element of the present invention has higher heat resistance and can efficiently heat the object to be heated.

It is sectional drawing which shows one Embodiment of the heater element of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1A, 1B ... Conductor 5 ... PTC member 10 ... Insulating layer 100 ... Heater element

Claims (2)

Comprising at least two conductors and a PTC member provided in contact with each of the two conductors;
The PTC member contains conductive particles and porous ceramic particles dispersed in a resin.   The heater element according to claim 1, wherein the porous ceramic particles are made of an alumina / silica composite oxide.

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