TWI407460B - Flexible positive temperature coefficient heating element, method for manufacturing the same and application thereof - Google Patents

Abstract

A flexible positive temperature coefficient (PTC) heating element is disclosed herein. The PTC heating element includes a textile substrate, at least one conductive line, a plurality of carbon black particles, and a resin protective layer. The conductive line is woven into the textile substrate, and the carbon black particles adhere to the surface or the interior of the textile substrate. The protective resin layer is disposed over at least one surface of the textile substrate.

Description

Flexible positive temperature coefficient heating element and its manufacturing method and application

The invention relates to a heating element, in particular to a flexible positive temperature coefficient (PTC) heating element.

In order to adapt to the cold climate, humans have developed many different technologies and equipment to provide warmth. In a large space, air-conditioning equipment can of course be used to provide heating; however, in terms of individual users, portable warming devices or other warm-up products that are in close contact with the human body are practical.

For example, there are many warm-up products (commonly known as warm packs) made by the principle of oxidation and heat generation of iron powder. However, when the user uses such a warming article, it is often difficult to safely control the heating temperature, and thus accidents such as burns often occur. In addition, most of these products are disposable products that generate waste after use.

In order to cope with the extremely cold climate, it has also been proposed to embed a tube in the laundry to deliver the heated gas to the tube so that the wearer feels warm. The user is usually able to control the gas temperature of such a device, so the safety is better than the above-mentioned warm package; however, such a device is expensive and can limit the freedom of movement of the user after wearing, so its use is limited. Ordinary users usually do not use such devices in their daily lives.

Another portable heating device uses nickel-chromium heating wires to provide thermal energy. Nickel-chromium heating wire has good durability and its shape can be freely changed; however, since the heat-generating portion is linear, it has to be heated at a high temperature in order to reach the desired temperature, and if it is in contact with a part of the heat-generating component, it is likely to be partially High temperature burns. In order to prevent such an accident from occurring while achieving an ideal heating effect, a plurality of heat generating portions and a temperature sensor are usually used to reduce the temperature generated by each of the heat generating portions. This will inevitably increase the cost price. In addition, the nickel-chromium heating wire emits a narrow range of far-infrared radiation when it is heated, which is also a disadvantage of such a product.

The positive temperature coefficient (PTC) component is a recently attracting heating element. The PTC component, also known as the thermistor component, has a nonlinear relationship between the resistance and the temperature generated after energization. Specifically, before the temperature reaches the transition temperature, the resistance decreases with increasing temperature; When the transition temperature is between the thermal runaway temperatures, the resistance increases significantly with increasing temperature. Therefore, based on the PTC effect described above, a PTC element suitable for different uses can be manufactured by adjusting the temperature coefficient of the material. Since the PTC element itself is a temperature-controlled heating element, when it is used as a heating element, it is not necessary to design an additional temperature control circuit. However, existing PTC heating elements are structurally rigid and therefore not flexible. As a result, PTC materials may be degraded or cracked during processing or use, which may affect the yield or service life of the PTC component, and also limit the applicable fields of the PTC.

In view of the above problems, it is urgent to propose a novel PTC material in the related field, and such PTC materials should have flexibility to expand the field of application and scope.

Therefore, the aspect of the invention proposes a method of manufacturing a PTC heating element. The PTC heating element manufactured by this method has flexibility, and thus can be widely used as a portable heating device or other heating/warming device that is in close contact with the human body.

According to an embodiment of the invention, the method comprises at least the following steps. Carbon black particles having a weight ratio of from about 1:1 to about 1:3 are mixed with water to form a PTC coating. At least one wire is woven onto the fabric substrate. The fabric substrate is impregnated into the PTC coating described above such that the carbon black particles in the coating are adsorbed to the surface and interior of the fabric substrate. The moisture in the impregnated fabric substrate is removed. A resin material is applied on at least one surface of the dried fabric substrate to form a resin protective layer. The fabric substrate is then subjected to a heat treatment at a temperature of about 150 to 200 ° C for the heat treatment and a heat treatment time of about 3-5 minutes.

In an optional embodiment, the preparation of the PTC coating comprises at least the following steps. A plurality of carbon black particles are mixed with paraffin to prepare a mixture. The above mixture was heated and stirred, and water was added to the mixture when the heating temperature reached about 60 °C. The mixture is further heated to a temperature of about 60-70 ° C while stirring is continued during the heating until the mixture forms a dispersion with water.

In an optional embodiment of the invention, the carbon black particles used in the PTC coating have a diameter of from about 10 to about 50 nanometers; in certain optional embodiments, the carbon black particles have a diameter of about 30 nanometers.

In still another embodiment of the present invention, a natural cotton cloth or a hollow fiber fabric can be utilized as the above-mentioned fabric substrate. For example, the natural cotton fabric described above has a web size of about 1 mm.

In an optional embodiment of the invention, the wire is first woven onto the fabric substrate and the fabric substrate is then impregnated into the PTC coating.

According to an optional embodiment, the method of manufacturing the above-described wire comprises at least the following steps. The plurality of chemical fibers are first integrated into a fiber bundle, and then a copper foil of about 1 mm width is spirally wound around the outside of the fiber bundle to form a wire. In general, the above chemical fibers have a heat resistance temperature of at least 150 °C. For example, the above chemical fibers may be polyester fibers, polyacrylonitrile fibers, polyamide fibers, polytrimethylene terephthalates fibers or polyterephthalic acid. Polybutylene terephthalate fiber.

In various embodiments, techniques such as infrared drying or air drying may be utilized to remove moisture from the impregnated fibrous substrate.

In another optional embodiment, styrene butadiene rubber (SBR) or Nitrile butadiene rubber (NBR) may be utilized to form the resin protective layer.

According to an optional embodiment, the method further comprises securing the at least one power supply terminal to at least one surface of the fabric substrate. For example, the power supply terminal can be fixed by riveting or crimping after the step of impregnating the textile substrate with the PTC coating. Alternatively, the power supply terminal can be fixed by means of silver solder. In one case, the power supply terminal is secured with silver solder prior to impregnating the woven substrate with the PTC coating. In another case, one part of the wire is made into a solderable state before the fabric substrate is impregnated with the PTC coating, and after the fabric substrate is impregnated with the PTC coating, it is fixed by soldering. Power supply terminal.

Another aspect of the present invention provides a PTC heating element fabricated using the foregoing aspects/embodiments. Such a PTC heating element has flexibility and can be widely used as a portable warming device or other heating/warming device that is in close contact with the human body.

According to an embodiment of the invention, the flexible PTC heating element comprises at least one textile substrate, at least one wire, a plurality of carbon black particles, and a resin protective layer. The wires are woven into the fabric substrate; the carbon black particles are adsorbed on the surface and inside of the fabric substrate. The resin protective layer covers at least one surface of the textile substrate.

In an optional embodiment, the carbon black particles are applied to the fibrous substrate in an amount of from about 50 to about 55 grams dry weight per square meter.

In an optional embodiment, the flexible PTC heating element further includes at least a waterproof layer disposed on the resin protective layer.

In another optional embodiment, when the heat-producing temperature of the flexible PTC heating element is about 40 ° C, far-infrared rays having a wavelength range of about 2 to 20 μm can be emitted.

PTC components can be divided into organic polymer PTC and ceramic PTC according to their manufacturing materials. The organic polymer PTC is formed by extruding carbon powder into a high molecular polymer by extrusion molding; in this case, the carbon powder forms a carbon chain conductive, the polymer expands when heated, and the carbon chain breaks to form a high electrical resistance. The ceramic PTC is formed by high temperature sintering of barium titanate powder with positive temperature coefficient characteristics by electronic ceramic process. Due to its high reliability, ease of use, and safe power saving, PTC components have been widely used in many fields such as household appliances, power facilities, electronic equipment, and the automotive industry; their use includes heating and line limits. Flow protection, overcurrent protection and overheat protection of motor transformers, sensors for electrical and electronic applications, etc.

The PTC heating element manufactured by the above method has a relatively rigid structure and hardly has flexibility. However, PTC heating elements on the market in the early days are usually used in relatively rigid structures such as floors, so there is no demand for flexible PTC heating elements, so related research and development applications are not available.

However, as the market demand for portable or other heating/heating devices that are in close contact with the human body is gradually increasing, the above-mentioned PTC heating elements are slowly applied to related products. However, such a PTC heating element may be deformed by external force during use, thereby causing peeling, cracking or even entire fracture of the element; not only the characteristics of the PTC heating element may be deteriorated, but the durability time of the product may be greatly reduced, and may even be damaged. user.

On the other hand, the PTC heating element must use a larger battery to provide sufficient current and limit the applicability of the PTC heating element.

In addition, the prior art proposes to print an oily PTC coating on a plastic film, but the solvent of the oily PTC coating is toxic, and the emitted solvent may pollute the environment during the preparation process. In addition, the use of such oily PTC coatings to prepare portable or other warmer devices that are in close contact with the human body may directly affect the health of users and those around them. .

In summary, there are still many deficiencies in existing PTC heating elements or other heating elements. In particular, when PTC heating elements are to be used in portable or other heating/heating devices that are in close contact with the human body, existing PTC heating elements have poor performance in terms of comfort and durability.

In view of the above problems, a water-soluble PTC coating is proposed here, thereby improving the permeability of the PTC coating of the impregnated material and also improving the electrical characteristics of the PTC coating. Compared with oil-based PTC coatings, water-based PTC coatings use water as the main solvent, so oily solvents that adversely affect the human body and the environment are not used.

By using such a water-soluble PTC coating and the method proposed herein, a flexible PTC heating element with high durability, high reliability and high safety can be manufactured, and the flexible PTC heating element can be applied to human body heating. A purpose is to achieve a heating/warming device that combines energy saving, small size, light weight, and convenience. Briefly, the specific embodiment of the present invention improves the disadvantages of the existing PTC heating element, and has a particularly effective effect on the portable heating device for direct heating to the human body, and gives new added value to the use of the PTC heating element. Industrial effect.

In particular, applying the principles and spirits set forth in the present disclosure has at least the following advantages.

First, the conventional PTC heating element becomes a defective product in a short period of time due to an external force generated during use. Now, the flexible structure is used to improve the situation, and the durability of the PTC heating element is prolonged. The number of years of durability.

Since the PTC heating element sometimes has to be in direct contact with the human body, it is necessary to use an insulating, waterproof material as the outer packaging. At present, the commonly used outer covering materials include hot pressing type and film type, and the two outer covering materials are directly contacted with the sintered carbonaceous material during processing, and the carbonaceous material is easily peeled off and the heating function is destroyed.

In addition, the flexible PTC heating element not only has flexibility, but also retains the same (or better) reliability and insulation as the existing PTC heating element, making it more widely used.

Based on the above characteristics, the flexible PTC heating element is made into an article suitable for human body heating, which can reduce energy waste. On the other hand, since the power consumption of the flexible PTC heating element is low, a smaller battery can be used, making the entire heating device more compact and lighter in weight and weight.

A method of practicing the principles and spirit of the present disclosure, and a flexible PTC heating element obtained by the method will be further described below.

One aspect of the present invention provides a method of fabricating a PTC heating element. The PTC heating element manufactured by this method has flexibility, and thus can be widely used as a portable heating device or other heating/warming device that is in close contact with the human body.

According to an embodiment of the invention, the method comprises at least the following steps. Carbon black particles having a weight ratio of from about 1:1 to about 1:3 are mixed with water to form a PTC coating. At least one wire is woven onto the fabric substrate. The fabric substrate is impregnated into the PTC coating described above such that the carbon black particles in the coating are adsorbed to the surface and interior of the fabric substrate. The moisture in the impregnated fabric substrate is removed. A resin material is applied to at least one surface of the dried fabric substrate and heat-treated to form a resin protective layer. The temperature used for the above heat treatment is about 150-200 ° C, and the heat treatment time is about 3-5 minutes.

Another aspect of the invention provides a PTC heating element made using the methods described herein. As shown in FIG. 3, according to an embodiment of the present invention, the PTC heating element 300 includes at least a textile substrate 305 in which a plurality of carbon black particles are adsorbed, at least one wire 310, and a resin protective layer 315. The wire 310 can be woven into the fabric substrate 305 using any conventional technique; and the resin protective layer 315 covers at least one surface of the fabric substrate.

In an optional embodiment, the preparation of the PTC coating comprises at least the following steps. A plurality of carbon black particles are mixed with paraffin to prepare a mixture. The above mixture was heated and stirred, and water was added to the mixture when the heating temperature reached about 60 °C. Heating and stirring are continued until the above mixture forms a dispersion with water. In this embodiment, the purpose of adding paraffin is to promote uniform dispersion of the carbon black particles in water. Generally, in the entire PTC coating, about 1-3% by weight of paraffin wax is used, which is sufficient for the purpose of dispersion.

In order to increase the uniformity of the distribution of the carbon black particles in the dispersion, in an optional embodiment of the present invention, the carbon black particles may be subjected to nanopulverization to obtain carbon black particles having a particle size of nanometer order. For example, the carbon black particles used in the PTC coating can have a diameter of about 10-50 nanometers, such as 10, 15, 20, 25, 30, 35, 40, 45 or 50 nanometers.

Since it is necessary to pass the impregnation step so that the carbon black particles are adsorbed on the surface or the inside of the textile substrate, it is necessary to use a fabric having a good adsorption ability. For example, natural cotton cloth has desirable heat resistance and is suitable for carbon black particles to be adsorbed inside the fabric substrate by being deep into the gap between the fibers. In still another embodiment of the present invention, a natural cotton cloth or a hollow fiber fabric can be utilized as the above-mentioned fabric substrate. The web of natural cotton depends on the use of the flexible PTC heating element. In one embodiment, the natural cotton cloth used has a web width of about 1 mm when the flexible PTC heating element is suitable for a voltage range of between 7 and 9 volts.

Of course, the above description is merely illustrative, and other natural fibers or synthetic fibers may be used as the fabric substrate described herein, and hollow fibers are one example.

The prior art system uses a printing method to form a carbon black layer on a plastic film; in contrast, it is proposed here that the carbon black penetrates into the interior of the fabric substrate by the impregnation technique, which not only makes the PTC heating element flexible, At the same time, it can also improve its heating efficiency.

Further, according to the above method, the resin material may be directly coated on at least one surface of the textile substrate to form a resin protective layer. The resin protective layer formed by such a method is also flexible, and has good adhesion to the woven substrate, and is not easily separated from the woven substrate even when subjected to bending, so that the woven fabric is greatly improved. Application and durability of flexible PTC heating elements. As for the existing products using the plastic film as the substrate, the flexural load resistance is poor. It is conceivable that this resin protective layer can also be formed on many or all surfaces of the textile substrate.

On the other hand, the use of a fabric having excellent heat resistance as a substrate makes it possible to heat-treat the flexible PTC heating element to further improve the heat generation efficiency. In contrast, existing products (based on plastic films) cannot withstand the high temperatures required for heat treatment.

Since the methods disclosed herein are used to fabricate flexible PTC components, the selected conductors should also have suitable flexibility. In an optional embodiment, the method of making the wire comprises at least the following steps. The plurality of chemical fibers are first integrated into a fiber bundle, and then a copper foil of about 1 mm width is spirally wound around the outside of the fiber bundle to form a wire. In certain embodiments, hundreds of very fine (e.g., about 0.003 mm diameter) chemical fibers can be integrated into a fiber bundle to produce the wires described above.

In general, the above chemical fibers have a heat resistance temperature of at least 150 °C. Examples of the above chemical fibers include, but are not limited to, polyester fibers (melting point of about 254 ° C), polyacrylonitrile fibers (melting point of about 317 ° C), polyamide fibers (such as Nylon 66, melting point of about 253 ° C), polyphenylene Ethylene formate fiber (melting point about 230 ° C) or polybutylene terephthalate fiber (melting point about 230 ° C).

In accordance with an optional embodiment of the present invention, the wire can be woven onto the fabric substrate and the fabric substrate then impregnated into the PTC coating. For example, an appropriate number of wires can be entangled and woven into a natural cotton cloth according to the amount of energization of the wires and the total amount of energization required for the flexible PTC heating element.

Specifically, the number of wires and the interval to be programmed should be designed according to factors such as the use environment, the output power of the flexible PTC heating element, and the amount of carbon black applied on the fabric substrate.

In general, when the current of a single wire is about 0.2 amps, the current in the environment can be calculated and the current capacity of the flexible PTC heating element is approximately twice the ambient current. Therefore, when the coating amount of carbon black on the flexible PTC heating element is about 50-55 grams per square meter dry weight, the flexible PTC heating element outputs about 2 watts at a voltage of about 9 volts. The power at power is about 0.23 amps. At this point, two wires are needed (current is about 0.4 amps, about twice the ambient current). As a result, when the length of the flexible PTC heating element is about 200 mm (ie, 0.2 m) and the power is about 400 watts/m 2 , the distance between the electrodes (between the two wires) is 2 ( Watt) ÷ 400 (watts / square meter) ÷ 0.2 (meters) = 0.025 (meters, equivalent to 25 mm).

The impregnated fibrous substrate can be dried in any suitable manner to substantially remove moisture contained therein. By way of illustration and not limitation, available drying methods are infrared drying or air drying.

In accordance with the principles and spirit of the present disclosure, a resin material can be applied to the dried fibrous substrate to form a resin protective layer. When the resin material is applied, the multilayer resin layer may be formed by a single application or multiple application.

Since the carbon black in the PTC heating element expands due to heat and causes a change in electrical resistance, a resin protective layer having a suitable flexibility should be used to prevent the resin protective layer covering the carbon black from affecting the heat generation performance. Examples of suitable resin materials include, but are not limited to, styrene butadiene rubber and nitrile rubber. When a multilayer resin layer structural formula is used, a resin layer directly contacting the carbon black (i.e., the innermost resin layer) should use a flexible resin material, and the other resin layers are not limited.

In addition, since the resin protective layer is directly coated on the surface of the fibrous base material, even if the carbon black particles are separated from the surface or the inside of the fibrous base material, the resin protective layer is still confined inside the flexible PTC heating element, so that it is used. On the top, the detached carbon black particles can still perform a certain function.

As described above, the flexible PTC heating element can be used in a portable or other heating device in close contact with the human body. The above resin protective layer can provide a certain degree of insulation, so in some fields of application, the flexible PTC heating element proposed herein does not require the use of an additional outer package.

However, when the flexible PTC heating element is used in daily life, it may be necessary to further make the flexible PTC heating element waterproof. For example, when it is placed in clothing (such as tops, pants, skirts, coats, socks, etc.), the wearer may sweat, so it is necessary to block sweat. Or, when it is applied to general household fabrics (such as carpets, sheets, quilts, cushions, etc.), it may be spilled by drinking water or other liquids, so it is also necessary to block these liquids. In an optional embodiment, a waterproof layer can be placed over the resin protective layer. For example, a fabric or cloth tape having waterproof properties can be placed over the resin protective layer. The description herein is merely illustrative, as other equal methods or structures may be used to render the flexible PTC heating element waterproof.

FIG. 4 is a schematic view showing the appearance of a PTC flexible heating element according to another embodiment of the present invention. In the present embodiment, the waterproof layer 420 is provided on the outer surface of the resin protective layer of the flexible PTC heating element 400, which is shielded by the waterproof layer, and thus is not shown. As for the wire 410, it must be partially exposed to be connected to an external circuit.

In the prior art, since the flexibility of the PTC heating element was not pursued, the manner in which the power supply terminal and the electric wire were installed did not take into consideration the characteristics of the flexible product. In view of the above, a method for mounting a power supply terminal and a fixed electric wire in a flexible PTC heating element is proposed.

In an optional embodiment, the power supply terminals and the wires can be mounted/fixed by riveting or crimping. At this time, after the woven fabric substrate is impregnated with the PTC coating and dried, the power supply terminal and the fixing member are brought into contact with the flexible PTC heating element by riveting or crimping. In this way, not only the electrical conductivity of the power supply terminal and the fixing component but also the problem of contact failure between the power supply terminal and the flexible PTC heating element can be prevented.

In another optional embodiment, silver solder can be utilized to secure the power supply terminals. For example, silver solder can be used to fix the power supply terminal on a fabric substrate impregnated with PTC coating, followed by immersion and drying of the PTC coating. Alternatively, the wire to be used as the fixing portion of the power supply terminal may be soldered to the fabric substrate impregnated with the PTC coating, and then subjected to immersion, drying, etc. of the PTC coating, and then The power supply terminal is fixed by soldering.

The performance of the flexible PTC heating element obtained according to the aspect/embodiment proposed herein will be clarified in a number of experimental examples.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a graph showing the resistance-temperature relationship of a PTC heating element and an existing PTC heating element in accordance with an embodiment of the present invention.

In Fig. 1, a broken line represents a flexible PTC heating element made using the prior art oily PTC coating; and a solid line represents an aqueous PTC coating (carbon black and water) using a specific embodiment of the present invention. The flexible PTC heating element produced by the weight ratio of 1:3). In general, the prior art oily PTC coatings are composed of carbon black and an oily solvent in a weight ratio of about 1:3, wherein the above oily solvent may be toluene or xylene.

Fig. 2 is a graph showing the resistance-current change of the PTC heating element of the above specific embodiment.

In another experimental example, a bending test was performed to confirm the flexibility of the PTC heating element proposed herein. First, it was made into a size of 40 mm × 150 mm × 1 mm, and a wide-width cloth tape was coated on the resin protective layer to provide waterproof performance of the PTC heating element. The bending test results show that the electrical characteristics of the flexible PTC heating element proposed herein have not deteriorated after 500 bending. On the other hand, in the case of the existing PTC heating element, electrical characteristics are deteriorated after less than 50 bending.

In order to further confirm the durability of the flexible PTC heating element proposed herein, in the following experimental examples, a flexible PTC heating element was prepared and simulated in use to estimate the durability of the flexible PTC heating element.

During the experiment, the power supply of the flexible PTC heating element was turned on/off 16 times a day. In each on/off test, the power supply time was 30 minutes, and then the power was turned off for 60 minutes, and then the next time. On/off test. This experiment has been carried out for two years, but in the actual use environment, it is assumed that each use is used once in the morning and evening, which is equivalent to the actual use of 8 days in the experiment, so the 2-year test period is equivalent to the actual use of the open. / Closed 5840 days (8*365*2=5840). Generally speaking, the season in which heating equipment is required is about 4 months from November to February of the next year (120 days in total). The number of days in this experiment is equivalent to 48 years (5840/365=48.67). / off the situation.

In this experimental example, a natural cotton cloth woven with a web of about 1 mm was used. However, basically, as long as the fabric capable of maintaining the network structure can be used, the width of the web is not particularly limited. The PTC coating used contained carbon black and water (about 1:3 by weight). Further, in the present experimental example, the wire interval was set to about 10 mm in accordance with conditions such as the power supply voltage and the heat generation temperature, but the present invention is not limited thereto.

Fig. 5 is a partial result at the beginning of the durability test of the PTC heating element according to the above experimental example; and Fig. 6 is a partial test result of the same PTC heating element in the second year. In Figs. 5 and 6, the vertical axis represents the temperature emitted by the PTC heating element, and the horizontal axis shows the specific time point during the test (the time points shown in Fig. 5 are January 28, 2005, respectively). Day, February 7, 2005, and February 17, 2005; the time points shown in Figure 6 are December 17, 2006, December 22, 2006, December 27, 2006, and 2007. January 1).

Referring to Figures 5 and 6, it can be seen that the flexible PTC heating element proposed herein has ideal durability, and the number of repeatable switches is equivalent to 48 years of actual use under simulated conditions.

According to an embodiment of the invention, the flexible PTC heating element proposed herein can be disposed in daily worn clothes to provide a warm-keeping effect with the body. Therefore, in an experimental example, a wear test was conducted.

In this experimental example, the flexible PTC heating element used was covered with a tarpaulin tape having a size of 40 mm × 150 mm × 1 mm; a battery output of 7.4 volts (initial value); and a maximum output power of 1.2 watts. The PTC heating element is laterally attached in the center of the vest, and is powered by the maximum output of the battery, and the heat state is measured in a worn state. Fig. 7 is a graph showing changes in the heating temperature of the PTC heating element as a function of time, wherein the vertical axis represents the heating temperature of the surface of the PTC heating element, and the horizontal axis represents a specific time point during the test ( They are 9:00, 11:00, 13:00, 15:00 and 17:00 on March 12, 2009.

The test results show that when the ambient average temperature is about 22 ° C, the surface temperature of the PTC heating element is raised to 40 ° C, and it can be continuously used for more than 8 hours.

In addition, since the fixed position of the PTC heating element is just at the site where the human aorta passes, after 20 minutes, the toes are warm, and a sufficient heating effect is achieved.

Further, since the heat generation temperature of the above-mentioned flexible PTC heating element is about 40 ° C, far infrared rays having a wavelength range of about 2 to 20 μm can be emitted. The far-infrared rays of this wavelength resonate with the moisture in the body, causing the self-heating of the water to obtain an effect of increasing the body temperature.

On the other hand, since the PTC heating element is made of cotton cloth and tarpaulin tape, and has the same flexibility as the cloth, it is installed on the wearing object, and the wearer does not feel uncomfortable. Can do business and other business.

Since fabrics are proposed as substrates for impregnating PTC coatings, these fabrics generally form a network structure, which is different from the conventional planar structure using a plastic film as a substrate. In terms of the effect and feeling of heating, when a planar structure and a mesh structure having an appropriate density are used as the heat generating elements, there is no significant difference between the two. However, in terms of power consumption, the power consumed by the planar structure is higher than the power consumed by the mesh structure.

In addition, the PTC heating element made of the planar structure can only emit heat by a single surface on which the PTC coating is printed. In contrast, a PTC heating element made using the mesh structure described herein can utilize the far infrared rays radiated from the side of the mesh structure to provide thermal energy. For example, when the far-infrared reflective material is disposed on the side that is not in direct contact with the body, the far-infrared rays that have passed through the mesh structure can be directly used, so that the utilization efficiency of the far-infrared rays can be made better.

By "mesh structure of appropriate density" is meant a structure that provides a heating effect similar to or substantially similar to a planar structure. In general, when the mesh structure is too large, it is difficult for the user to feel the heat, so it is necessary to have an appropriate radiation density. After a series of experiments, it was found that the coverage of the mesh structure can provide an appropriate heating effect as long as it reaches at least 20% of the entire plane.

In addition, it was further found during the experiment that the use of such a mesh structure successfully reduced the power consumption of the PTC heating element during heating. Specifically, if the heat generation density of the mesh structure is reduced to 20% of the planar structure, the theoretical power consumption will also become 20%. In this way, in the case of using the same battery, the use of the flexible PTC heating element proposed herein will provide a longer heating effect. From another perspective, the battery capacity can also be reduced to provide a suitable heating time. Therefore, the volume and weight of the portable heating device can be easily reduced by using the flexible PTC heating element proposed herein.

Fig. 8 is a graph showing the relationship between the power consumption of the PTC heating element and the time when the user wears the clothes shown in Fig. 7. In Fig. 8, the vertical axis represents the heat generation temperature of the surface of the PTC heating element, and the horizontal axis represents the specific time point during the test (19:00, 21:00, 23:00, and 2009, respectively, on March 13, 2009). 1 o'clock and 3 o'clock on March 14).

The use time of the existing portable heating equipment is set to 4 hours. In this test, the battery can be used continuously for more than 11 hours depending on the use environment. Therefore, the capacity (and volume) of the battery can be reduced to provide a more lightweight portable heating device.

As described above, the characteristics of the flexible PTC heating element developed according to the present invention can be effectively utilized by attaching the PTC heating element to a human body or the like, and it is possible to provide a shape suitable for the body type. The flexible structure also combines high durability, high reliability, and high safety. On the other hand, due to its low power consumption, it is possible to provide a small-sized, lightweight air-heating device, improve the user's freedom and convenience in use, and apply the excellent effects of the PTC heating element itself. In the vast world.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the present invention, and the present invention can be modified and modified without departing from the spirit and scope of the present invention. The scope is subject to the definition of the scope of the patent application attached.

300. . . Flexible PTC heating element

305. . . Fabric substrate

310. . . wire

315. . . Protective layer only

400. . . Flexible PTC heating element

410. . . wire

420. . . Waterproof layer

The above and other objects, features, advantages and embodiments of the present invention will become more apparent and understood.

1 is a resistance-temperature relationship diagram of a PTC heating element and an existing PTC heating element according to an embodiment of the present invention;

2 is a resistance-current change diagram of a PTC heating element according to the above specific embodiment of the present invention;

3 is a schematic structural view of a PTC heating element according to an embodiment of the present invention;

4 is a schematic view showing the appearance of a PTC heating element according to another embodiment of the present invention;

Figure 5 is a graph showing the results of the durability test of the PTC heating element in accordance with an embodiment of the present invention;

Figure 6 is a partial result of the durability test shown in Figure 5 after two consecutive years;

Figure 7 is a diagram showing the temperature change of the PTC heating element with time when the PTC heating element according to an embodiment of the present invention is placed in the laundry and the subject wears the clothing;

Fig. 8 is a view showing the time-dependent change of the power consumption of the PTC heating element in the environment in which the PTC heating element according to an embodiment of the present invention is placed in the clothes and the subject wears the clothes.

Claims (28)

A method for manufacturing a flexible positive temperature coefficient heating element, comprising: preparing a positive temperature coefficient coating comprising at least a plurality of carbon black particles and water, wherein a weight ratio of carbon black particles to water is from about 1:1 to about 1 : 3; weaving at least one wire on a fabric substrate; impregnating the fabric substrate with the positive temperature coefficient coating such that the carbon black particles are adsorbed on the surface and the interior of the fabric substrate; drying the An impregnated fabric substrate to remove water therein; a resin material applied over at least one surface of the dried fabric substrate to form a resin protective layer; and a fabric base to which the resin material is applied The material is subjected to a heat treatment wherein the temperature of the heat treatment is about 150 to 200 ° C, and the heat treatment time is about 3-5 minutes. The manufacturing method of claim 1, wherein the step of preparing a positive temperature coefficient coating comprises at least: preparing a mixture comprising at least a plurality of carbon black particles and paraffin; heating and stirring the mixture when heated When the temperature reaches about 60 ° C, water is added to the mixture, wherein the weight ratio of the carbon black particles to the water is from about 1:1 to about 1:3, and the weight percentage of the paraffin in the positive temperature coefficient coating is About 1-3%; and heating and stirring are continued to maintain the temperature of the mixture at about 60-70 ° C until the mixture forms a dispersion with water. The manufacturing method according to claim 1, wherein the carbon black particles have a diameter of about 10 to 50 nm. The manufacturing method of claim 3, wherein the carbon black particles have a diameter of about 30 nm. The manufacturing method of claim 1, wherein the fabric substrate is a natural cotton cloth or a hollow fiber fabric. The manufacturing method of claim 5, wherein the natural cotton fabric has a web size of about 1 mm. The manufacturing method according to claim 1, further comprising at least woven the wire on the textile substrate before impregnating the textile substrate with the positive temperature coefficient coating. The manufacturing method of claim 1, wherein the method of manufacturing the wire comprises at least: integrating a plurality of chemical fibers into a fiber bundle; and winding a copper foil of about 1 mm width in a spiral shape on the fiber bundle The outside is formed to form the wire. The manufacturing method according to claim 8, wherein the chemical fiber has a heat-resistant temperature of 150 °C. The manufacturing method according to claim 8, wherein the chemical fibers are polyester fibers, polyacrylonitrile fibers, polyamide fibers, polyethylene terephthalate fibers or polybutylene terephthalate. fiber. The manufacturing method according to claim 1, wherein the drying is performed by infrared drying or air drying. The manufacturing method according to claim 1, wherein the resin is styrene butadiene rubber or nitrile rubber. The manufacturing method of claim 1, further comprising fixing a power supply terminal to at least one surface of the fabric substrate. The manufacturing method according to claim 13, wherein after the fabric substrate is impregnated with the positive temperature coefficient coating, the power supply terminal is fixed by riveting or crimping. The manufacturing method according to claim 13, wherein the power supply terminal is fixed by silver solder before the fabric substrate is impregnated with the positive temperature coefficient coating. The manufacturing method of claim 13, wherein a part of the wire is made into a solderable state before the fabric substrate is impregnated with the positive temperature coefficient coating, and the fabric base is After the material is impregnated with the positive temperature coefficient coating, the power supply terminal is fixed by soldering. A flexible positive temperature coefficient heating element produced by the method of claim 1, wherein the flexible positive temperature coefficient heating element comprises at least: a fabric substrate; at least one wire, It is woven into the fabric substrate; a plurality of carbon black particles are adsorbed on the surface and the inside of the fabric substrate; and a resin protective layer covering at least one surface of the fabric substrate. The flexible positive temperature coefficient heating element of claim 17, wherein the carbon black particles have a diameter of about 10-50 nm. The flexible positive temperature coefficient heating element of claim 17, wherein the carbon black particles have a diameter of about 30 nm. The flexible positive temperature coefficient heating element of claim 17, wherein the fabric substrate is a natural cotton cloth or a hollow fiber fabric. The flexible positive temperature coefficient heating element of claim 20, wherein the natural cotton has a web of about 1 mm. The flexible positive temperature coefficient heating element according to claim 17, wherein the wire comprises at least one fiber bundle formed by a plurality of chemical fibers; and a copper foil wound spirally on the outer side of the fiber bundle, Wherein the copper foil has a width of about 1 mm. The flexible positive temperature coefficient heating element of claim 22, wherein the chemical fiber has a heat resistant temperature of 150 °C. The flexible positive temperature coefficient heating element according to claim 22, wherein the chemical fibers are polyester fibers, polyacrylonitrile fibers, polyamide fibers, polyethylene terephthalate fibers or poly pairs. Butylene phthalate fiber. The flexible positive temperature coefficient heating element according to claim 17, wherein a material of the resin protective layer is styrene butadiene rubber or nitrile rubber. The flexible positive temperature coefficient heating element of claim 17, wherein the carbon black particles are coated on the fibrous substrate by a dry weight of about 50-55 grams per square meter. The flexible positive temperature coefficient heating element according to claim 17, further comprising at least one waterproof layer disposed on the resin protective layer. The flexible positive temperature coefficient heating element according to claim 17, wherein the flexible positive temperature coefficient heating element emits far infrared rays having a wavelength range of about 2-20 μm at a heat generation temperature of about 40 °C.