KR20070068770A - Manufacturing method of carbon fiber for sheet heater - Google Patents

Abstract

A method of manufacturing a carbon fiber for a sheet-type heater is provided to maintain a maximum heated temperature for a long time by adjusting a heating temperature by regulating a voltage applied on a calorific plate. A PAN(PolyAcryloNitrile) group carbon fiber or a pitch group carbon fiber is carbonated at a middle temperature between 700 and 900 degrees centigrade in an inert atmosphere, so that a carbon fiber with a weight ratio between 55 and 65% with respect to an initial weight is obtained. An AC voltage calorific plate is obtained by carbonating the PAN group oxide fiber or the pitch group carbon fiber at a middle temperature between 700 and 800 degrees centigrade in the inert atmosphere to obtain a yield between 60 and 65%. A DC voltage calorific plate is obtained by carbonating the PAN group oxide fiber or the pitch group carbon fiber at a middle temperature between 800 and 900 degrees centigrade in the inertia atmosphere to obtain a yield between 55 and 60%.

Description

Manufacturing method of carbon fiber for sheet heater

1 is a graph comparing measured exothermic temperatures in Example 7, Example 8 and Example 9 of the present invention.

The present invention is a partial carbonization fan (PAN) system which is partially carbonized by carbonizing a fan (PAN; polyacrylonitrile) oxidized fiber (Oxy-PAN, hereinafter referred to as "oxy fan") or a pitch-based oxidized fiber at medium temperature After preparing the carbon fiber or the partial carbon pitch-based carbon fiber, to prepare a non-woven fabric or woven fabric made of the partial carbon carbon fiber for the planar heating element, and the partial carbon carbon fiber for the planar heating element or the prepared planar It relates to a planar heating element and a manufacturing method using a non-woven fabric or a fabric made of partially carbonized carbon fiber for the heating element.

In addition, the present invention is prepared by installing a metal electrode at both ends of the non-woven fabric or fabric made of the partial carbon carbon fiber for the planar heating element and the partial carbon carbon fiber for the planar heating element, and then laminated the insulating material up and down and thermally compressed It relates to a planar heating element and a manufacturing method.

The conventional method for producing a planar heating element is to use mostly carbon fiber, this manufacturing method has a problem that the temperature distribution deviation of the finally produced planar heating element has a problem that can not be uniformly applied to the carbon fiber. In addition, since carbon fiber is very expensive, it acts as a major cause of increasing the manufacturing cost, and the problem of causing a temperature deviation due to frequent occurrence of a problem of moving or twisting the carbon fiber due to pressure during hot press molding. In addition, the existing carbon fiber through the electricity as described above has a problem that is limited to the application field because it has a property that is broken or broken.

Another manufacturing method is to prepare a conductive ink by mixing a common thermoplastic polymer as a binder (carbon) with a carbon powder, although not widely used, there is a limit to the coating area because the coating method on the heating paper is silk screen printing method, Since the coating method by the pressing force does not always make the angle of the force and the squeegee blade has a problem that the coating thickness is different, causing the temperature deviation is increased.

Another manufacturing method is to use an organic binder, which is poor in heat resistance and has a poor durability, thus causing a problem of acting as a risk factor in a fire.

An object of the present invention is a non-woven fabric comprising a partial carbonized carbon fiber for a planar heating element or a partial carbonized carbon fiber for a planar heating element manufactured by carbonizing a PAN-based or pitch-based carbon fiber at a medium temperature; It relates to a cotton heating element and a manufacturing method made of a fabric.

The present invention provides a partial carbonized carbon fiber for planar heating element by carbonizing a pan-based oxide fiber or a pitch-based oxide fiber in an inert atmosphere to obtain a yield of 55 to 65% relative to the initial weight at 700 to 900 ° C. It relates to a method for producing and a planar heating element containing the partially carbonized carbon fiber for the planar heating element prepared above.

As the carbon fiber raw material used in the present invention, a fan (PAN; Polyacrylonitrile) -based oxide fiber (Oxy-PAN, oxy-fan) and a pitch-type oxide fiber are used. The pan-based oxide fiber or pitch-based oxide fiber is an oxide fiber that has undergone a stabilization process to prevent melting or deformation during carbonization and to increase strength. As a reinforcing fiber of a composite material that is widely used in various applications because it exhibits properties, conductivity, heat resistance, chemical stability, and lubricity, it is used in various applications due to its characteristics such as light weight, high strength, and high rigidity.

The PAN-based carbon fiber or Pitch-based carbon fiber is mesocarbonized to obtain a yield of 55 to 65% of the initial weight at 700 to 900 ℃ in an inert atmosphere to a carbon-based partial carbon (PAN) carbon A fibrous or partially carbonized pitch carbon fiber is obtained, and the obtained partial carbonized fan (PAN) carbon fiber or partially carbonized pitch carbon fiber is hereinafter referred to as 'partial carbon fiber for planar heating element'. . The mesophilic carbonization process is heat-treated at a temperature increase rate of 1 to 3 ℃ / min.

By controlling the heat treatment temperature of the mid-temperature carbonization process for producing the partial carbon carbon fiber for the planar heating element according to the present invention, it is possible to produce the partial carbon carbon fiber for the AC voltage planar heating element and the partial carbon carbon fiber for the DC voltage planar heating element.

In order to obtain the heat treatment temperature of the mesophilic carbonization process at 700 to 800 ° C. in a yield of 60 to 65% relative to the initial weight, a partial carbon carbon fiber for an AC voltage planar heating element is produced, and the heat treatment temperature of the mesophilic carbonization process is Partial carbonized carbon fiber for a DC voltage planar heating element was prepared by mesophilic carbonization to obtain a yield of 55 to 60% relative to the initial weight at 800 to 900 ° C.

The resistance of the woven or nonwoven fabric made of the partial carbon carbon fiber for the planar heating element and the partial carbon carbon fiber for the planar heating element after the mid-temperature carbonization process was measured using a resistance measuring instrument (Hewlett Packard, HP34401A) The exothermic temperature was measured with an infrared temperature measuring instrument (SATO, SK-8700II, Japan).

The woven fabric or nonwoven fabric consisting of the partial carbonized carbon fiber for the AC voltage planar heating element and the partial carbonized carbon fiber for the AC voltage planar heating element is obtained at 60 to 65% of the initial weight at 700 to 800 ° C. It has a resistance value of 1000 mW / m 2, exhibits a power consumption of 100 to 1000 (watt / m 2) when applying a voltage of AC220V, an exothermic temperature of 30 to 120 ° C., and an initial weight to 800 to 900 ° C. A woven or nonwoven fabric composed of a partial carbonized carbon fiber for a DC voltage planar heating element and a partial carbonized carbon fiber for a DC voltage planar heating element, which is obtained in a yield of 55 to 60%, has a resistance value of 5 to 25 mW / m 2, Exothermic temperature of 50-120 degreeC was shown.

The heat treatment temperature of the mesophilic carbonization process is a mid temperature of 700 to 900 ° C., which is lower than the carbonization temperature of 1000 to 1500 ° C. of general carbon fibers. When heat treated at normal carbonization temperature, fully carbonized carbon fiber is fragile and has limited resistance to use as a heating element, and is limited to use. In the case of general PAN oxide fiber (oxyfan), nitrogen and hydrogen contained Although it was difficult to conduct electricity with the oxygen content of more than 40%, the partially carbonized carbon fiber, which has undergone the mesophilic carbonization process according to the present invention, has different functional groups introduced during the oxidation process according to the bond dissociation energy through the mesophilic carbonization process. Condensation and polymerization between carbons occur at different temperatures, resulting in a relatively increased proportion of the carbon component, which allows electricity to pass through well, and weakness in cracking and breaking, which can be used as a conductive fiber for various applications.

The partial carbonaceous carbon fiber for the planar heating element manufactured through the mesophilic carbonization process is composed of short fibers or long fibers or a nonwoven fabric or fabric made from the short fibers or long fibers.

The partial carbonaceous carbon fiber for the planar heating element consisting of the short fibers or the long fibers is twisted and converted into a yarn and then made into a nonwoven fabric or fabric, or a general fan-based carbon fiber or pitch-based carbon fiber into a nonwoven fabric or fabric. After the preparation may be subjected to the medium temperature carbonization process as described above.

The nonwoven fabric manufactured by using the partial carbon carbon fiber of the short fiber or long fiber is mixed with the partial carbon carbon fiber and the refractory fiber of the short fiber or long fiber, separated by one strand by a carding machine, and then collected in parallel. It is made of a sliver (sliver), the sliver is arranged in a nonwoven fabric in one direction, and then manufactured by heat bonding, the fabric produced by using the short carbon fiber or long carbon fiber carbon fiber of partial carbon fiber and The refractory fibers are mixed and separated by strands by a carding machine to make them evenly parallel, and then collected and made into slivers, which are twisted to give the slivers and are manufactured by spinning the yarns.

In addition, the non-woven fabric or fabric made of the partial carbon carbon fiber for the planar heating element or the partial carbon carbon fiber for the planar heating element made of short fibers or long fibers may be oxidized while being worn in use. It effectively protects the surface of the non-woven fabric or fabric made of the partial carbon carbon fiber for the planar heating element and the partial carbon carbon fiber for the planar heating element, and protects the product and the electric shock of the planar heating element made of the nonwoven fabric and the fabric. Insulating coating the surface of the non-woven fabric or fabric made of the partial carbon carbon fiber for the planar heating element and the partial carbon carbon fiber for the planar heating element made of short fibers or long fibers to be waterproof.

The coating material is one or more selected from polyethylene, polyester, polystyrene, polyamide, polycarbonate, polyurethane, acrylic, polypropylene, polyvinyl chloride (PVC), polyethylene terephthalate (PET), and polyethylene terephthalate. The surface is hardened when coated with, but polyurethane can be used to enhance flexibility.

The planar heating element according to the present invention is installed after the electrode portion parallel to both ends of the non-woven fabric or fabric made of the partial carbon carbon fiber for the planar heating element and the partial carbon carbon fiber for the planar heating element manufactured through a medium temperature carbonization process, the insulating material 2, 4 and 6 pieces are stacked up and down by thermal compression, and heat is generated when a voltage is applied through an electrode part of the planar heating element.

However, due to the characteristics of the heating element, when the voltage is repeatedly turned on and off, the carbons in the parts in contact with the electrodes are more stressed, and the resistance is increased due to severe deterioration, short circuit, and arc in the parts in contact with the electrodes. There is a problem.

In order to solve the above problems, in the present invention, a conductive powder selected from silver, copper, and aluminum is printed in a paste form in contact with an electrode part and a nonwoven fabric or fabric made of partially carbonized carbon fiber and partially carbonized carbon fiber. As a result, arcing and carbon deterioration can be prevented.

The electrode part is located at both ends of the carbon heating element of the nonwoven fabric or the fabric made of the partial carbon fiber and the partial carbon carbon fiber, and the flexible, high strength and economical copper tape (width 10mm) is excellent in electrical conductivity and low resistance. Electrode treatment is applied to nonwoven fabrics or fabrics made of partially carbonized carbon fibers and partially carbonized carbon fibers.

In addition, by using a metal yarn such as copper, nickel, or stainless steel, the electrode portion can be manufactured by weaving together with the carbonized carbon fibers, and the metal buffer layer is required because the carbonized carbon fibers and the metal fibers are bonded in a wide cross-sectional state. There is no.

The insulating material is epoxy impregnated glass fiber (prepreg) ("GLASS EPOXY LAMINATE" manufactured by DooSan Electromaterials Co., Ltd.), and is composed of the above-mentioned partial carbon carbon fiber or partial carbon carbon fiber having copper electrodes installed at both ends. 2, 4, 6, etc. according to the desired thickness of the nonwoven fabric or fabric made of the partial carbon carbon fiber or the partial carbon carbon fiber, wherein the copper electrode is installed at both ends after cutting more loosely than the nonwoven fabric or fabric. Several sheets are stacked and hot pressed to gradually increase the pressure from 3 to 8 Kg / m 2 to a temperature of up to 180 ° C. at a temperature of up to 180 ° C., followed by thermocompression and quenching to produce a planar heating element.

[Production Example 1] Partial Carbonization Fan (PAN) Carbon Fiber for AC Voltage Planar Heating Element

1250 g of oxidized polyacrylonitrile (Oxy-PAN) fiber (Japan Teijin Co., Ltd.) of 7 cm length in a nitrogen atmosphere was heat treated at 500 ° C. for 30 minutes, and then carbonized at 800 ° C. for 1 hour in medium carbonization. 800 g of PAN-based carbon fibers were obtained.

After applying silver paste on the obtained carbonized fan (PAN) carbon fiber 1cm, the resistance was measured on a silver paste electrode with a resistance meter (Hewlett Packard, HP34401A), and the power consumption was measured by fixing the voltage to 220V, and set a certain point. Afterwards, the exothermic temperature was measured using an infrared temperature measuring instrument (SATO, SK-8700II, Japan). The prepared partially carbonized PAN-based carbon fiber exhibited a resistance of 0.8 mW / m 2 and a power consumption of 850 (watt / m 2) and an exothermic temperature of 75 ° C.

Preparation Example 2 Fabrication of Nonwoven Fabric Made of PAN-Based Carbon Fiber for AC Voltage Planar Heating Element

500 g of 7 cm long partially carbonized fan (PAN) based carbon fiber prepared in Preparation Example 1 and 500 g of aramid fiber, which is a refractory fiber (Low Melting fiber), were mixed in a mixer, separated by one strand by a carding machine, and aligned in parallel. Then, this was collected and made into a sliver, and the slivers were arranged in a nonwoven fabric in one direction, and then thermally bonded at 150 ° C. to prepare a nonwoven fabric made of PAN-based carbon fibers. The manufactured nonwoven fabric was manufactured in a roll type of nonwoven fabric having a width of 1000 mm, a length of 60 m, a thickness of 40 gsm, and a weight of 55 g / m 2, and a resistance of 120 kV was measured when a voltage of 220 V was applied, and an exothermic temperature of 80 ° C. was obtained. Indicated.

Preparation Example 3 Fabrication of PAN-Based Carbon Fiber for AC Voltage Planar Heating Element

500 g of 7 cm long partially carbonized fan (PAN) based carbon fiber prepared in Preparation Example 1 and 500 g of aramid fiber, which is a refractory fiber (Low Melting fiber), were mixed in a mixer, separated by one strand by a carding machine, and aligned in parallel. Then, it was collected and made into a sliver, and twisted on the sliver to spun and weave 30 thin threads to prepare a fabric made of PAN-based carbon fiber. The fabric is a roll type of 350mm in width, 1000mm in length, 450g / m2 in weight, exhibits a power consumption of 500 (Watt / m2) when a voltage of 220V is applied, and a resistance of 90 Ω was measured. Exothermic temperature was shown.

Production Example 4-5 Coating of Nonwoven Fabric or Fabric Consisting of PAN Carbon Fiber for AC Voltage Planar Heating Element

The upper and lower portions of the nonwoven fabric or fabric (size 40 cm x 30 cm) prepared in Preparation Examples 3 and 4 were hot pressed with a polyethylene terephthalate film (size 42 cm x 31 cm) at a pressure of 3 Kg / m 2 at room temperature to 100 ° C. for 2 hours. The surface of the nonwoven or woven fabric was coated by heat rising slowly over.

Production Example 6 Fabrication of Nonwoven Fabric Planar Heating Element Made of Partial Carbon Fan (PAN) Carbon Fiber for AC Voltage Planar Heating Element

After printing silver paste on both ends of the non-woven fabric (0.6mx 0.8 m, 60gsm) made of a partial carbonization fan (PAN) -based carbon fiber for AC voltage planar heating element, the copper tape (width 10mm) is printed on the silver paste. ) And the epoxy-impregnated glass fibers ("GLASS EPOXY LAMINATE" manufactured by DooSan Electromaterials Co., Ltd.) were cut in a margin of 0.8mx 1.0m more comfortably than the nonwoven fabric made of PAN-based carbon fibers. Laminated by two sheets at the top and bottom of the non-woven fabric, and slowly pressurized by heating and pressing over 5 hours from room temperature to 180 ℃ while applying a pressure of 5Kg / ㎡ with a hot press, and then quenched to prepare a planar heating element in the form of a non-woven fabric, The planar heating element of the type exhibited a resistance of 16kV when applied at 220V.

[Example 1] Measurement of resistance of nonwoven fabric and woven fabric made of PAN based carbon fiber according to carbonization temperature

Oxyfan fibers (Asahisansangyo Co., Ltd.) having a size of 50 mm x 100 mm were maintained at 500 ° C for 30 minutes in a batch type electric carbonization furnace in which an inert atmosphere using nitrogen gas was formed, followed by 2 ° C / min. After raising the temperature at a rate of temperature increase and partially carbonized, it was maintained at 800 ° C. for 2 hours, and maintained at the final temperature for 1 hour to prepare a partially carbonized partial carbonized fan (PAN) -based carbon fiber. The non-woven fabric and the woven fabric made of the partial carbonization fan (PAN) carbon fiber by the method of Preparation Example 2-3 using the partial carbonization fan (PAN) -based carbon fiber prepared according to the temperature and then measured the resistance Table 1 shows. The resistance value was measured using a resistance measuring instrument (Hewlett-Packard, HP34401A) with a non-woven fabric made of PAN-based carbon fiber and a fabric of 30 mm x 50 mm, respectively, and having a point distance of 50 mm.

TABLE 1

Pan-based carbon fibers were carbonized three times in the same manner to prepare nonwoven fabrics and woven fabrics, respectively. As shown in Table 1, in the case of the nonwoven fabric and fabric type made of PAN-based carbon fiber partially carbonized at 700 ° C., the resistance value is very high and the amount of current flowing decreases. However, in the case of the nonwoven fabric and the fabric type made of PAN-based carbon fiber partially carbonized at 900 ° C., the resistance value is very low and the amount of current flowing increases to increase the heat generation. But too much heat can overwhelm the device and burn it. As can be seen from Table 1, it can be seen that the nonwoven fabric and the fabric type made of PAN-based carbon fiber partially carbonized at 700 to 800 ° C., in which the resistance value is drastically reduced, have the most appropriate resistance value as the planar heating element.

In addition, from Table 1, the resistance of the nonwoven fabric was 1.5 to 4.5 times higher than that of the woven fabric, because the fiber length of the nonwoven fabric was shorter than the woven fabric and the bonding degree was low.

[Example 2] Measurement of resistance of a fabric type made of PAN-based carbon fiber for a planar heating element carbonized at various carbonization temperatures

Carbonizing the oxy-pan fiber at the same temperature three times at a temperature of 600 to 900 ℃ to produce a partial carbonized fan (PAN) -based carbon fiber for the planar heating element to the resistance of the fabric type made of the partial carbonized fan (PAN) -based carbon fiber It measured by the same method as Example 1, and is shown in following Table 2. In addition, Table 2 below shows the weight of the oxyfan fiber before carbonization and the weight of the partial carbonization fan (PAN) carbon fiber after carbonization, and compared the yields.

TABLE 2

In the case of the fabric type consisting of the partial carbonized fan (PAN) -based carbon fiber from Table 2, using a fabric made of a partial carbonized fan (PAN) -based carbon fiber manufactured by carbonizing the oxyfan fiber at 750 to 770 ℃ as a planar heating element It was found to have an appropriate resistance of 275 to 123 kV. From Table 2, it can be seen that the difference in weight before and after carbonization, which includes hydrogen, oxygen and nitrogen in addition to carbon inside the oxyfan fiber. As a result, 35 to 45% of the initial weight is released into the atmosphere, so that the PAN-based carbon fiber has a relatively higher carbon content than the general carbon fiber. In addition, it was found that having a yield of 55 to 65% by going through the medium temperature carbonization process has the most suitable resistance value when fabricating a planar heating element in the future. Since it has a problem, it cannot be manufactured with a planar heating element.

[Example 3-6] Measurement of Resistance and Exothermic Temperature of Nonwoven Fabric and Fabric Made of Partial Carbon Fan (PAN) Carbon Fiber for DC Voltage Planar Heating Element

In order to manufacture the DC voltage planar heating element, the resistance value and the exothermic temperature of the nonwoven fabric and the fabric type made of partially carbonized fan (PAN) -based carbon fiber at the carbonization temperature of 800 to 900 ° C shown in Table 3 were measured. Indicated. The DC 12V voltage was used, and the resistance was measured in the same manner as in Example 1 after fabricating a non-woven fabric and fabric made of PAN-based carbon fiber in a size of 30 mm x 50 mm, and then measuring the point distance to 50 mm. (Hewlett-Packard, HP34401A), and the exothermic temperature is the average value of the measured value by dividing the exothermic area by 32 equals, the temperature deviation was within ± 5 ℃.

TABLE 3

As can be seen from Table 3, a non-woven fabric or fabric made of a partial carbonized fan (PAN) based carbon fiber for a DC voltage planar heating element is manufactured by using a carbonized fan (PAN) based carbon fiber according to a temperature at which the oxyfan fiber is carbonized. Could. In addition, since it exhibits a resistance of 5 to 25 kPa and an exothermic temperature of 50 to 120 ° C. according to the carbonization temperature, it was found that the exothermic temperature can be adjusted according to the purpose by adjusting the carbonization temperature.

Example 7-9 Exothermic Temperature of Planar Heating Element According to Voltage

Cut the planar heating element of Preparation Example 6 into a size of 30cm x 40cm while measuring the exothermic temperature with an infrared temperature measuring device (Japan SATO, SK-8700II) at 15 points every 10 minutes while changing the voltage to AC 20 to 50V The average values are shown in Table 4 below and compared graphically in FIG. 1.

TABLE 4

As shown in Table 4 and FIG. 1, the planar heating element according to the present invention has a temperature increase time to a maximum heating temperature of 3 to 6 minutes for each voltage, and a maximum heating temperature is applied when a voltage of 20 V is applied in Example 7. When a voltage of 40 V was applied at 32 ° C. and Example 8, the temperature was measured to 58 ° C. and 73 ° C. when a voltage of 50 V was applied in Example 9.

Accordingly, it can be seen from Table 4 that the heating temperature can be adjusted to the purpose by changing the voltage of the planar heating element according to the present invention. The heating temperature becomes the maximum heating temperature within a short time and the heating temperature is maintained even after the time elapses.

Nonwoven or woven fabric and partial carbonized carbon fiber made of PAN-based carbon fiber and P-based carbon fiber and PAN-based carbon fiber manufactured according to the present invention. Planar heating element comprising a non-woven fabric or woven fabric is energy saving by heating the cotton, and by using a carbon material does not generate electromagnetic waves, it is possible to adjust the heating temperature according to the purpose by changing the voltage, up to the desired temperature The rise time is short within 5 minutes, light weight, and even if partial damage occurs, there is no problem in the overall heat generation and there is no risk of fire because the temperature does not rise above the temperature set at the time of manufacture. In addition, clean heating without smell, noise and smoke is possible, and it is convenient to carry and flexible, and it can be used as a heating material such as heating vest, cold protection, heating mat.

Claims (14)

Partial carbon carbon for planar heating elements, characterized in that the carbon fiber (PAN) or pitch-based carbon fibers in the inert atmosphere to obtain a yield of 55 to 65% of the initial weight at 700 to 900 ℃ Method of making fibers. The method of claim 1, Plane carbon fiber or pitch carbon fiber in an inert atmosphere, characterized in that for the AC voltage planar heating element obtained by mesophilic carbonization to obtain a yield of 60 to 65% of the initial weight at 700 to 800 ℃ Method for producing partially carbonized carbon fiber for a heating element. The method of claim 1, Fan-shaped carbon fiber or pitch carbon fiber in the inert atmosphere, characterized in that for DC voltage planar heating element obtained by mesophilic carbonization to obtain a yield of 55 to 60% relative to the initial weight at 800 to 900 ℃ Method for producing partially carbonized carbon fiber for a heating element. The method of claim 2 or 3, The PAN-based carbon fibers and the pitch-based carbon fibers are prepared in the form of short fibers or long fibers, or a non-woven fabric or a woven fabric made from the short fibers or long fibers. Way. The method of claim 2 or 3, A method for producing partial carbonaceous carbon fiber for a planar heating element, characterized by maintaining a temperature increase rate of 1 to 3 ° C / min. The method of claim 2 or 3, Partial carbonization for planar heating elements, characterized in that the short fibers or long fibers of the PAN-based carbon fibers and the Pitch-based carbon fibers are mixed with refractory fibers after mid-temperature carbonization, manufactured into a woven or nonwoven fabric, and then coated with a coating material. Method for producing carbon fiber. The method of claim 6, The coating material is a planar heating element, characterized in that at least one selected from polyethylene, polyester, polystyrene, polyamide, polycarbonate, polyurethane, acrylic, polypropylene, polyvinyl chloride (PVC), polyethylene terephthalate (PET) Method for producing partially carbonized carbon fiber. A planar heating element containing partially carbonized fibers and nonwoven or woven fabric of a PAN-based carbon fiber and a Pitch-based carbon fiber produced by the manufacturing method according to claim 2. The method of claim 8, Planar heating element characterized by a resistance adjustable to 0.2 to 1.0 내지 / ㎡ and an exothermic temperature of 40 to 120 ℃. The method of claim 8, A planar heating element, which is made of nonwoven fabric or fabric by mixing short fibers or long fibers and refractory fibers of a partial carbonization fan (PAN) -based carbon fiber and a pitch-based carbon fiber. The method of claim 8, After printing a metal paste on both ends of the non-woven fabric or fabric, and forming an electrode portion, the planar heating element characterized in that the insulating material is laminated up and down by hot pressing (hot press). The method of claim 11, The metal paste is a planar heating element, characterized in that the conductive powder selected from silver, copper or aluminum. The method of claim 11, The electrode unit is a planar heating element, characterized in that the copper tape is attached to the non-woven fabric or fabric or manufactured by weaving metal fibers selected from copper, nickel and stainless steel and partially carbonized carbon fiber. The method of claim 11, The insulating material is a planar heating element, characterized in that the epoxy impregnated glass fiber.

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