Recycled carbon fiber manufacturing apparatus and method for manufacturing recycled carbon fiber using the same

Abstract

The present invention relates to an apparatus for producing recycled carbon fibers, and more particularly to an apparatus for producing recycled carbon fibers by utilizing induction heating due to high-frequency electromagnetic radiation from carbon fibers in carbon fiber mixed waste, and a method for producing recycled carbon fibers using the same.

Description

Technical Field

[0001] The present invention relates to a recycled carbon fiber manufacturing apparatus, an apparatus for manufacturing recycled carbon fiber by utilizing inductive heating by high-frequency electromagnetic radiation of carbon fiber in carbon fiber mixed waste, and a method for manufacturing recycled carbon fiber using the same.

Background Art

[0002] Carbon fiber is usually used to produce composite materials containing woven, chopped, or milled carbon fiber within a resin matrix. Such composite materials can be very light, strong, and durable.

[0003] Carbon fiber includes folded sheets of carbon layers. Such carbon fiber is usually non-reactive and thus resistant to fire and corrosion. Each fiber can have a diameter of about 7 microns. Carbon fiber composite materials composed of resin and continuous, cut, or milled carbon fiber impregnated therein can have high tensile strength and relatively low density. Therefore, many applications for such substances have been developed.

[0004] Although it has become clear that the demand for carbon fiber is high while the amount of substances discarded in the production process is considerable, it is estimated that about 40% of new carbon fiber and resin are discarded in the carbon fiber production process. These substances have conventionally been sent to landfills.

[0005] Currently, commercially produced recycled carbon fiber (rCF) is in the form of receiving raw materials from scraps of carbon fiber prepreg generated in the composite material manufacturing process and carbon fiber reinforced polymer composite waste that has passed its service life.

[0006] As a conventional technique, Japanese Patent Application Laid-Open No. 2008-285601 (November 27, 2008) discloses a technique related to a carbon fiber recycling apparatus and a recycling method that selectively recover carbon fibers by thermally removing only the matrix component from carbon fiber reinforced plastics without degrading the mechanical properties. Also, Japanese Patent Application Laid-Open No. 2011-122032 (June 23, 2011) discloses a technique for recovering carbon fibers in a state where 68 to 80% of the plastic is removed by treating carbon fiber reinforced plastics with superheated steam at 800°C or higher.

[0007] Recycled carbon fibers are manufactured by mechanical recycling technology, and some chemical recycling technologies tend to be developed. In the case of mechanical recycling, the removal of the polymer matrix is performed by a heat treatment process. At this time, in order to improve the efficiency of the heat treatment process, carbon fiber mixed waste (prepreg scrap, CFRP, etc.) is processed into a small crushed form through primary pretreatment by shredding, crushing, pulverizing, or similar mechanical processes, and then recycled carbon fibers are obtained through pyrolysis of the polymer matrix by heat treatment in an inert atmosphere.

[0008] On the other hand, in the case of the above primary pretreatment process (shredding, crushing, pulverizing, etc.), it leads to a decrease in the aspect ratio and non-uniformity of the recycled carbon fibers, and thus excellent physical properties cannot be expected. Moreover, the existing thermal decomposition of the polymer matrix in an inert atmosphere mainly uses hot air (5×10 -1 W / cm), radiant heat (8W / cm), etc., so it has low energy efficiency. For sufficient thermal decomposition, a batch-type facility using a rotary drum is operated, making it difficult to introduce continuous manufacturing equipment. In addition, long-time heat treatment must be performed for sufficient thermal decomposition of the polymer matrix, so there is a constraint that the equipment construction cost and operation cost are set high, and research related to improving the efficiency of the recycled carbon fiber manufacturing technology has been continuously conducted.

[0009] In addition, in the case of hot air or radiant heat used for removing the polymer matrix during the mechanical recycling process, for CFRP waste having a laminated structure by heating from the surface of carbon fiber waste (CFRP, prepreg scrap), and for prepreg scrap where a polymer resin exists between fibers, an external heat source must reach the polymer resin existing inside to completely remove it. In this case, however, it is necessary to rely on the characteristics of the polymer resin with a relatively low heat transfer rate among the recycling target components.

[0010] Thus, the thermal decomposition of the polymer matrix by supplying heat from the outside of the existing recycling target components (such as hot air and radiant heat) has a disadvantageous aspect in terms of shape for performing uniform heat treatment of the fiber bundle. Therefore, the development of a recycling process using a new heat source is required.

[0011] Therefore, in order to produce recycled carbon fibers with almost no physical damage and having a high aspect ratio, the research team developed a recycled carbon fiber manufacturing apparatus that utilizes the inductive heating of carbon fibers contained in polymer composites by high-frequency electromagnetic radiation, and a method for manufacturing recycled carbon fibers using the same.

Prior Art Documents

Patent Documents

[0012]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0013] The main object of the present invention is to solve the above-mentioned problems, and to provide a regenerated carbon fiber manufacturing apparatus that utilizes the inductive heating caused by the high-frequency electromagnetic radiation of carbon fibers contained in a polymer composite material without using an external heat source such as hot air or radiant heat.

Means for Solving the Problems

[0014] To achieve the above object, an embodiment of the present invention is a regenerated carbon fiber manufacturing apparatus, which includes a main body portion, a gas inlet installed on one side surface of the main body portion, a gas outlet installed on the other side surface of the main body portion, one induction coil penetrating one side surface of the main body portion and the other side surface opposite thereto, a number of induction coils built into the case of the main body portion, a number of magnetic cores built between the number of induction coils, and a current application device for supplying current to the induction coil. The outer surface of the case of the main body portion is finished with a heat insulating material, and it is characterized in that carbon fiber mixed waste is processed by inductive heating caused by high-frequency electromagnetic radiation generated from the induction coil to produce regenerated carbon fiber, and a regenerated carbon fiber manufacturing apparatus is provided.

[0015] In a preferred embodiment of the present invention, an inert gas may be injected into the gas inlet.

[0016] In a preferred embodiment of the present invention, the gas outlet can discharge the gas generated in the carbon fiber mixed waste treatment process.

[0017] In a preferred embodiment of the present invention, a temperature sensing unit for measuring the temperature of the reaction region inside the main body portion can be further installed on one side surface of the main body portion.

[0018] In a preferred embodiment of the present invention, a control unit for controlling the frequency, current, and power of the alternating current applied by the current application device according to the temperature extracted from the temperature sensing unit can be further installed.

[0019] In a preferred embodiment of the present invention, the frequency of the alternating current supplied from the current application device may be 200 to 300 kHz, the current may be 200 to 350 A, and the power may be 1500 to 2500 W.

[0020] In another preferred embodiment of the present invention, the present invention provides a method for manufacturing regenerated carbon fibers from carbon fiber mixed waste using the regenerated carbon fiber manufacturing apparatus.

[0021] In a preferred embodiment of the present invention, the carbon fiber mixed waste may contain any one or two or more polymer matrices selected from a thermoplastic polymer resin and a thermosetting polymer resin.

[0022] In a preferred embodiment of the present invention, the treatment temperature of the carbon fiber mixed waste by induction heating may be in the range of 350 to 1000 °C.

Advantages of the Invention

[0023] The regenerated carbon fiber manufacturing apparatus according to the present invention utilizes the induction heating by high-frequency electromagnetic radiation of the carbon fibers contained in the polymer composite material without using an external heat source such as hot air or radiant heat. Compared with the pyrolysis process using the heat transfer method by surface heating of an existing reactor, since the heating efficiency is high, economical and rapid heating is possible, the power consumption for warming up and the like can be reduced, and the process consumption time can be effectively shortened.

[0024] Also, the induction heating by high-frequency electromagnetic radiation is easy and convenient for output and temperature control, hygienic without generation of pollutants such as stability and exhaust gas, and clean.

[0025] In addition, when treating carbon fiber mixed waste using the regenerated carbon fiber manufacturing apparatus according to the present invention, the pretreatment process (such as a pulverization process) of the carbon fiber mixed waste can be omitted. Therefore, there is almost no physical damage to the regenerated carbon fiber, and regenerated carbon fiber having a high aspect ratio can be obtained. Such high-quality regenerated carbon fiber can be reused in various fields.

Brief Description of the Drawings

[0026]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0027] Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as commonly understood by a skilled person in the technical field to which the present invention belongs. In general, the nomenclature used in this specification is well known and commonly used in this technical field.

[0028] Throughout the specification of this application, when a certain part "includes" a certain component, this means that, unless otherwise stated to the contrary, it does not exclude other components, but can further include other components.

[0029] The present invention provides a regenerated carbon fiber manufacturing apparatus, which includes a main body 100, a gas inlet 101 installed on one side surface of the main body, a gas outlet 102 installed on the other side surface of the main body, a single induction coil 103-1 penetrating one side surface of the main body and the other side surface opposite thereto, a number of induction coils 103-2 built into the case of the main body, and a number of magnetic cores 104 built between the number of induction coils. The outer surface of the case of the main body is finished with a heat insulating material 105, and is characterized in that carbon fiber mixed waste is treated by induction heating caused by high-frequency electromagnetic radiation generated from the induction coil to manufacture regenerated carbon fiber.

[0030] That is, the regenerated carbon fiber manufacturing apparatus according to the present invention is used to effectively separate regenerated carbon fiber from carbon fiber mixed waste by pyrolyzing a polymer matrix surrounding the carbon fiber in the carbon fiber mixed waste, etc. through induction heating of the carbon fiber caused by high-frequency electromagnetic radiation generated from the center of the main body and the induction coils 103-1 and 103-2 built into the case of the main body.

[0031] FIG. 1 is a diagram showing a schematic configuration of a regenerated carbon fiber regeneration apparatus according to the present invention.

[0032] In FIG. 1(a), the appearance of the regenerated carbon fiber regeneration apparatus according to the present invention is shown. As shown in FIG. 1(a), the regenerated carbon fiber regeneration apparatus according to the present invention includes a main body 100, a gas inlet 101 provided on one side surface of the main body for injecting an inert gas to prevent deterioration of physical properties due to oxidation reaction of carbon fiber, and a gas outlet 102 provided on the other side surface of the main body for discharging the gas generated by the pyrolysis reaction of the polymer matrix occurring in the reaction region inside the main body.

[0033] At this time, the shape of the main body 100 is preferably cylindrical, but is not limited thereto.

[0034] In Fig. 1(b), an internal schematic diagram of the regenerated carbon fiber regeneration device according to the present invention is shown. In the regenerated carbon fiber regeneration device according to the present invention, an induction coil for forming a high-frequency electromagnetic field that generates induced heat of carbon fiber is installed in the main body and the case of the main body. Specifically, one induction coil 130-1 penetrating one side surface of the main body and the other side surface opposite thereto is installed, and a large number of induction coils 130-2 are built into the case of the main body, so that a high-frequency electromagnetic field is uniformly formed in the reaction region within the main body.

[0035] When the shape of the main body 100 is cylindrical, a uniform high-frequency electromagnetic field is formed between one induction coil 130-1 penetrating the main body and a large number of induction coils 130-2 in the case of the main body, so that uniform induced heat can be generated in the reaction region within the main body.

[0036] At this time, the diameter of one induction coil 130-1 penetrating the main body is preferably in the range of 1 / 30 to 1 / 10 of the diameter of the main body, and the diameter of a large number of induction coils 130-2 in the case of the main body is preferably in the range of 1 / 50 to 1 / 10 of the diameter of the main body.

[0037] Here, the shapes of the induction coils 130-1 and 130-2 are not limited to cylindrical shapes, and may be prismatic shapes.

[0038] In FIGS. 1(c) and 1(d), the cross-section of the case of the main body part in the regenerated carbon fiber regeneration device according to the present invention is shown. A large number of induction coils 130-2 are built into the case of the main body part, and by including a large number of magnetic cores 104 built between the induction coils 130-2 built into the case of the main body part, the loss of the high-frequency electromagnetic field generated from the induction coils can be minimized. The magnetic core can be made of a ferromagnetic material composed of a fired ferrite, ferrite resin, amorphous alloy, permalloy and other oxides, or alloys and magnetic materials having a high magnetic permeability, or a nano composite material added with a magnetic material. In particular, when an alternating high-frequency current is applied to the induction coil, a fired ferrite with small loss by the alternating high-frequency current can be used as the magnetic core material.

[0039] As an example, the nano composite material added with the magnetic material can use a nano composite substance manufactured by mixing silicon-iron (Si-Fe) alloy powder and epoxy resin.

[0040] In addition, by finishing the outer surface of the case of the main body part with a heat insulating material, it is possible to prevent the induced heat generated by the high-frequency electromagnetic radiation from being dissipated to the outside.

[0041] The regenerated carbon fiber regeneration device according to the present invention does not depend on the heat transmitted from the surface of the carbon fiber mixed waste, and is used as an energy source for directly generating induced heat from the carbon fibers in the carbon fiber mixed waste by the high-frequency electromagnetic field formed by one induction coil 103-1 passing through the main body part and a large number of induction coils 103-1 built into the case of the main body part, thereby thermally decomposing organic substances such as the polymer matrix in the carbon fiber mixed waste.

[0042] As an example, for the regenerated carbon fiber recycling device according to the present invention, a temperature sensing unit for measuring the temperature of the reaction region inside the main body can be further installed on one side surface of the main body, and a control unit for controlling the frequency, current, and power of the alternating current applied by the current application device according to the temperature extracted from the temperature sensing unit can also be further installed. At this time, the induction heating by high-frequency electromagnetic radiation via the temperature sensing unit and the control unit is convenient as the output and temperature control are easy.

[0043] For the regenerated carbon fiber recycling device according to the present invention, a current application device is connected to the induction coil. The frequency of the alternating current supplied from the current application device is preferably in the range of 200 - 300 kHz, the current is 200 - 350 A, and the power is 1500 - 2500 W. Since it is variable depending on the composition and size of the recycled material, it is not limited to this.

[0044] As the frequency of the alternating current applied to the induction coil increases, due to the Skin Depth Effect, the heat generation of the object to be heated is limited to the surface. Therefore, when directly treating carbon fiber mixed waste without primary pretreatment of the carbon fiber mixed waste, it is preferable not to exceed the upper limit value of the alternating current frequency range.

[0045] Figure 2 shows the configuration and driving flow of the current application device of the high-frequency electromagnetic field generation equipment used in the present invention. The electrical energy input via the AC power supply passes through a converter, an inverter, and a transformer, and is input to the induction coil in the form of a high-frequency current. The periphery of the induction coil generates a high-frequency electromagnetic field due to the high-frequency current flowing through the induction coil. As a result, eddy currents are generated from the dielectric material (carbon fiber) applied to the object to be heated, and heat is generated due to their specific resistance.

[0046] The present invention also provides a method for manufacturing regenerated carbon fiber from carbon fiber mixed waste using the one regenerated carbon fiber manufacturing device.

[0047] The carbon fiber mixed waste can contain any one polymer matrix selected from thermoplastic polymer resins such as PA, PBT, PET, and PEEK, or thermosetting polymer resins such as epoxy, phenol, vinyl ester, and urethane.

[0048] As an example, the treatment temperature of the carbon fiber mixed waste by the induced heat generation can be in the range of 350 to 1000 °C. A thermal decomposition reaction can occur for most polymer matrices within the above temperature range, and preferably it can be in the temperature range of 700 to 900 °C. Here, the treatment temperature of the mixed waste can be set to the temperature at which the polymer matrix in the input carbon fiber mixed waste is thermally decomposed.

[0049] Example Using an alternating current of 263 KHz, 270 A, and 1953 W, the carbon fiber reinforced polymer composite material composed of epoxy resin (decomposition temperature 500 °C) was processed by the regenerated carbon fiber regeneration device according to the present invention.

[0050] As shown in Figure 3, the thermal decomposition of the composite material began to be observed in less than 1 second by driving the regenerated carbon fiber regeneration device.

[0051] As described above, specific parts of the content of the present invention have been described in detail. However, it will be apparent to those with ordinary knowledge in the art that such specific technologies are merely preferred embodiments and do not limit the scope of the present invention. Therefore, the substantial scope of the present invention should be defined by the appended claims and their equivalents.

Explanation of Reference Numerals

[0052] 100 Main body 101 Gas inlet 102 Gas outlet 103 Induction coil 104 Magnetic core 105 Heat insulator

Claims

1. A regenerated carbon fiber manufacturing apparatus, comprising: a main body; a gas inlet installed on one side surface of the main body; a gas outlet installed on the other side surface of the main body; one induction coil penetrating through one side surface of the main body and the other side surface opposite thereto; a plurality of induction coils built in the case of the main body; a plurality of magnetic cores built between the plurality of induction coils; and a current application device for supplying current to the induction coils, wherein the outer surface of the case of the main body is finished with a heat insulating material, and characterized in that regenerated carbon fibers are manufactured by treating carbon fiber mixed waste by induction heating caused by high-frequency electromagnetic radiation generated from the induction coil. A regenerated carbon fiber manufacturing apparatus.

2. The regenerated carbon fiber manufacturing apparatus according to claim 1, wherein an inert gas is injected into the gas inlet.

3. The regenerated carbon fiber manufacturing apparatus according to claim 1, wherein the gas outlet discharges gas generated in the carbon fiber mixed waste treatment process.

4. The regenerated carbon fiber manufacturing apparatus according to claim 1, further comprising a temperature sensing unit installed on one side surface of the main body for measuring the temperature of the reaction region inside the main body.

5. The regenerated carbon fiber manufacturing apparatus according to claim 4, further comprising a control unit for controlling the frequency, current, and power of the alternating current applied by the current application device according to the temperature extracted from the temperature sensing unit.

6. The regenerated carbon fiber manufacturing apparatus according to claim 1, wherein the frequency of the alternating current supplied from the current application device is 200 to 300 kHz, the current is 200 to 350 A, and the power is 1500 to 2500 W.

7. A method for manufacturing regenerated carbon fibers from carbon fiber mixed waste using the regenerated carbon fiber manufacturing apparatus according to any one of claims 1 to 6.

8. The method for manufacturing regenerated carbon fibers from carbon fiber mixed waste according to claim 7, wherein the carbon fiber mixed waste contains any one or two or more polymer matrices selected from a thermoplastic polymer resin and a thermosetting polymer resin.

9. The method for manufacturing regenerated carbon fibers from carbon fiber mixed waste according to claim 7, wherein the treatment temperature of the carbon fiber mixed waste by induction heating is 350 to 1000 °C.

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