Regenerated fiber manufacturing method

Abstract

The invention relates to a manufacturing method of regenerated fibers. The manufacturing method comprises the following steps: putting a pretreated fiber composite material into a material box; moving a material box containing the pretreated fiber composite material; exposing the cartridge to superheated steam and an oxidant; removing a matrix resin and a charred material (char) from the pre-treated fiber composite material to produce a regenerated fiber; and moving the magazine containing the regenerated fibers and collecting the regenerated fibers from the magazine, the method being capable of improving the decomposition rate of the fiber composite material while minimizing the reduction in tensile strength of the finally produced regenerated fibers.

Description

Technical Field

[0001] The invention relates to a method for producing regenerated fibers. Background Art

[0002] Fiber composites are typically materials made by mixing carbon fibers or glass fibers with thermosetting or thermoplastic resins (matrix resins). They are widely used as materials with high strength, high elasticity, lightweight properties, heat resistance, and chemical resistance, as well as in industries such as aerospace, wind power generation, and automotive. However, the strong bond between carbon and glass fibers and the resin in fiber composites makes them difficult to separate. In particular, when made from thermosetting resins, these materials cannot be reused, and as a result, most of them are discarded and incinerated or landfilled. Recently, regulations on the disposal of waste composite materials such as carbon composites have been tightening. In Europe, incineration is prohibited, while in some countries, landfilling is limited, but landfill restrictions are gradually expanding. Therefore, technologies for recovering carbon or glass fibers from fiber composites can reduce the generation of waste that poses environmental problems and are economically valuable from the perspective of reusing expensive carbon or glass fibers.

[0003] Currently, the technologies for recovering carbon fibers from fiber composite materials generally fall into two categories: pyrolysis and solvolysis. Pyrolysis is widely used due to its simple process, but its drawbacks include the generation of resin residue (char) on the surface of the regenerated fibers after decomposition, which can degrade the physical properties of the recovered carbon fibers (regenerated fibers). Furthermore, heating large-capacity furnaces requires significant energy, and the decomposed resin is converted into gaseous substances and released, contributing to air pollution. Solvolysis, while widely considered environmentally friendly due to its stable physical properties and the absence of waste gas, presents challenges in handling and recovering the decomposition products containing solvents that are discharged through wastewater. Solvolysis also presents challenges in the relatively long decomposition reaction time and the need to adjust decomposition conditions, such as the solvent, time, and temperature, depending on the type and composition of the resin being decomposed. Furthermore, solvolysis requires essential processes such as pretreatment, decomposition reaction, water washing, and drying, resulting in complex and time-consuming processes.

[0004] Therefore, the recent research and development direction is to seek a composite decomposition technology, that is, an economical technology that can reduce the disadvantages of pyrolysis, namely energy consumption, and minimize the disadvantages of solvent decomposition, namely complex processes and long decomposition time, while also being an environmentally friendly technology that can reuse decomposition products produced by resins other than carbon fibers. Summary of the Invention

[0005] Technical issues In view of this, in order to solve the above problems, the inventors of the present invention conducted multi-angle research and finally completed a regenerated fiber manufacturing method, which can prevent the physical properties of regenerated fibers such as carbon fibers recovered from fiber composite materials from degrading, and at the same time can cool and condense superheated steam to convert it into water, and after recovery, the decomposition product, namely resin, can be reused through separation and purification.

[0006] Therefore, an object of the present invention is to provide an environmentally friendly method for producing regenerated fibers that can obtain regenerated fibers with suppressed deterioration in physical properties.

[0007] Technical Solution In order to achieve the above-mentioned object, the present invention provides a method for producing regenerated fiber, which includes the following steps: putting a pre-treated fiber composite material into a material box; moving the material box containing the pre-treated fiber composite material and exposing the material box to superheated steam and an oxidant, thereby removing matrix resin and char from the pre-treated fiber composite material to produce regenerated fiber; moving the material box containing the regenerated fiber and collecting the regenerated fiber from the material box.

[0008] The step of exposing the magazine to superheated steam and an oxidant may be a step of first exposing the magazine containing the pretreated fiber composite material to superheated steam, and then moving the magazine and exposing it to the oxidant.

[0009] The present invention may further include the following steps: first exposing the material box containing the pre-treated fiber composite material to superheated steam, and then using cooling water to condense the gaseous matrix resin decomposed from the pre-treated fiber composite material into liquid for removal before subsequently exposing it to an oxidant.

[0010] The step of condensing the gaseous matrix resin decomposed from the pre-treated fiber composite material into liquid and removing it can be the following step: by exposing it to the superheated steam, the gaseous matrix resin decomposed from the pre-treated fiber composite material is separated from the material box and reacts with cooling water that exists independently of the material box, thereby becoming liquid condensed water and being removed.

[0011] The oxidant may include air.

[0012] The fiber composite material can be made by mixing carbon fiber, glass fiber or a mixture thereof with a matrix resin.

[0013] The base resin may include an aromatic hydrocarbon compound.

[0014] The aromatic hydrocarbon compound may include a phenol compound.

[0015] The aromatic hydrocarbon compound may include bisphenol A. The content of bisphenol A may be greater than 30 wt % relative to the total amount of the aromatic hydrocarbon compound.

[0016] The pretreated fiber composite material may be a shredded or cut fiber composite material.

[0017] The temperature of the superheated steam may be in the range of 400°C to 900°C.

[0018] The magazine containing the pretreated fiber composite material may be exposed to the superheated steam for 30 to 120 minutes.

[0019] The step of exposing to superheated steam may include the step of spraying the superheated steam toward a magazine containing the pre-treated fiber composite material, wherein the superheated steam is sprayed toward the magazine at a flow rate of 10 kg / h to 30 kg / h.

[0020] The step of exposing to the oxidant may include spraying the superheated steam into the magazine containing the pretreated fiber composite material, and then spraying the oxidant into the magazine, wherein the oxidant is sprayed into the magazine at a flow rate of 5 L / min or more.

[0021] The present invention may further include the following step: after the step of placing the pre-treated fiber composite material into the magazine, before exposing the magazine to the superheated steam, first exposing the magazine to nitrogen.

[0022] The present invention may further include the step of exposing the magazine containing the regenerated fibers to nitrogen gas before moving the magazine containing the regenerated fibers after the step of producing the regenerated fibers.

[0023] The char may be present on the surface of the regenerated fiber from which the matrix resin has been removed.

[0024] Beneficial effects The regenerated fiber manufacturing method of the present invention uses a pre-treated fiber composite material, exposes the pre-treated fiber composite material to superheated steam, controls the temperature, exposure time, flow rate, etc. of the superheated steam during exposure to the superheated steam, and further, in addition to the superheated steam, an oxidant such as air with a separately controlled flow rate is additionally added, thereby minimizing the reduction in the physical properties of the recovered regenerated fiber. Furthermore, by using a material box method rather than a roller method, the process defect rate is significantly reduced, and the process is simple, thereby significantly shortening the process time, and by using cooling water rather than external air, the matrix resin, which is one of the decomposition products, is converted into condensed water, thereby facilitating the reuse of the matrix resin. Furthermore, condensed water can be generated quickly, thereby significantly reducing energy consumption. Therefore, compared with existing pyrolysis methods, etc., the economy and productivity of the regenerated fiber manufacturing process can be significantly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a flowchart sequentially showing the method for producing regenerated fibers of the present invention. DETAILED DESCRIPTION

[0026] Hereinafter, the present invention will be described in more detail.

[0027] The advantages and features of the technology described below, as well as its implementation methods, will become more apparent with reference to the various specific implementation examples described below. However, the implementations are not limited to the multiple implementation examples disclosed below. Unless otherwise defined, all terms (including technical and scientific terms) used in this specification are to be used as commonly understood by those skilled in the art. Furthermore, unless otherwise specifically defined, idealized or excessive interpretations of commonly used dictionary terms should not be applied.

[0028] The terms used in the present invention are only used to explain specific embodiments and are not intended to limit the present invention. Unless otherwise defined, a singular expression includes a plural expression.

[0029] In the present invention, terms such as "including" or "having" should be understood as intending to specify the existence of the features, numbers, steps, operations, constituent elements, parts or their combinations recorded in the specification, rather than excluding in advance the existence or additional possibilities of one or more other features or numbers, steps, operations, constituent elements, parts or their combinations.

[0030] Superheated steam is a dry steam state formed by vaporizing water and heated to a temperature above its saturation temperature. It is a heat medium with a higher heat content than heated air. At the same pressure, superheated steam has a high heat transfer rate and high heat density, enabling rapid heating of objects, shortening the heating time. Furthermore, as a gaseous substance composed solely of water molecules and lacking oxygen, superheated steam remains inert and conducts heat through a combination of heat transfer methods (convection, radiation, and condensation), resulting in extremely high thermal efficiency. Therefore, the use of superheated steam to recover recycled fibers, such as carbon fibers, offers the advantage of faster resin removal due to the direct injection of superheated steam onto the object being decomposed.

[0031] However, the physical properties of recycled carbon fibers, such as regenerated fibers, inevitably degrade. When the physical properties of regenerated fibers are severely degraded, they cannot be reused. Furthermore, the resin decomposed along with the regenerated fibers itself poses a significant risk of environmental pollution. Therefore, there is a constant need for further improvements in decomposition technology using superheated steam.

[0032] After accurately understanding the aforementioned market needs and conducting extensive research, the inventors of the present invention have developed a method for producing regenerated fibers using superheated steam injection. Unlike conventional methods that use rollers to move fiber composite materials, this method utilizes a cartridge rather than rollers to move the fiber composite materials. Furthermore, cooling water, rather than ambient air, is used to condense the gaseous matrix resin decomposed by the superheated steam injection. This significantly improves the environmental friendliness, cost-effectiveness, and productivity of the regenerated fiber manufacturing process. (In particular, the use of rollers previously often generated environmental issues such as dust, but this is eliminated with the cartridge. Furthermore, the cartridge can be cleaned and reused continuously, whereas rollers require periodic replacement, making the use of the cartridge more environmentally friendly.) Furthermore, the fiber composite material is pre-treated and exposed to superheated steam. The temperature, exposure time, and flow rate of the superheated steam are controlled to minimize degradation of the physical properties of the recycled carbon fibers, resulting in the production of regenerated fibers with superior physical properties compared to conventional recycled fibers.

[0033] Reference Figure 1 , the regenerated fiber manufacturing method of the present invention is described, which includes the following steps: step S100, putting the pretreated fiber composite material into a material box; step S200, moving the material box containing the pretreated fiber composite material; step S300, exposing the material box to superheated steam and an oxidant; step S400, removing matrix resin and char from the pretreated fiber composite material to produce regenerated fiber; and step S500, moving the material box containing the regenerated fiber and collecting the regenerated fiber.

[0034] Specifically, the pre-treated fiber composite material is decomposed by superheated steam into regenerated fibers and matrix resin. The regenerated fibers are sequentially moved through the magazine and recovered. The matrix resin, as described below, is converted from gaseous state to liquid condensate by cooling water and moved to a condensate tank. After separation and purification, it can be reused. The recovered regenerated fibers can be reused through chopping and milling.

[0035] In other words, through the method for producing regenerated fibers of the present invention, regenerated fibers with minimized degradation of physical properties and reusable matrix resin can be easily obtained from a fiber composite material simultaneously through a series of continuous processes.

[0036] Specifically, the step of exposing the cartridge to the superheated steam and the oxidant may be as follows: first exposing the cartridge containing the pre-treated fiber composite material to the superheated steam, and then subsequently moving the cartridge and exposing it to the oxidant. Exposing the cartridge to the superheated steam first is more conducive to removing matrix resin and char than exposing it to the oxidant first.

[0037] For example, the method for producing regenerated fibers of the present invention may further include the following steps: after exposing the material box containing the pre-treated fiber composite material to superheated steam, and before subsequently exposing it to an oxidant, using cooling water to condense the gaseous matrix resin decomposed from the pre-treated fiber composite material into a liquid state for removal. By using cooling water rather than external air to condense the matrix resin decomposed from the pre-treated fiber composite material, the matrix resin can be removed more easily and thoroughly. Specifically, by being exposed to the superheated steam, the gaseous matrix resin decomposed from the pre-treated fiber composite material is separated from the material box and reacts with the cooling water that exists independently of the material box to become liquid condensed water, which can be moved to a separate condensation water tank for ultimate removal.

[0038] Fiber composite materials suitable for superheated steam decomposition generally fall into two categories: carbon fiber composites (CFRP) and glass fiber composites (GFRP). Regardless of their structure, form, or material, they can be used for decomposition. They are typically composed of a mixture of a reinforcing material and a matrix resin. Fibrous materials used for the reinforcing material include carbon fiber and glass fiber, while the matrix resin includes thermosetting resins such as epoxy resin, phenol, unsaturated polyester, polyurethane, melamine, and urea, as well as thermoplastic resins such as polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyamide, polycarbonate, and polyimide. Commonly used fiber composites are a mixture of the aforementioned reinforcing materials and a matrix resin in a specified ratio. The ratio of reinforcing material to resin varies depending on the intended use.

[0039] For example, the base resin may include an aromatic hydrocarbon compound, the aromatic hydrocarbon compound may include a phenol compound, the phenol compound may include phenol, o-cresol, p-cresol, p-ethylphenol, p-isopropylphenol, p-isopropenylphenol, p-hydroxy-2,2-diphenylpropane, p-hydroxy-3-methyl-2,2-diphenylpropane, 2-(4-hydroxyphenyl)-2-(4'-methoxyphenyl)propane, bisphenol A, 2-(4-hydroxy-3-methylphenyl)-2-(4'-hydroxyphenyl)propane, 2-(benzofuran-5-yl)-2-(p-hydroxyphenyl)propane or a combination thereof, but is not limited thereto.

[0040] However, the aromatic hydrocarbon compound, specifically, the phenol compound may include bisphenol A.

[0041] For example, bisphenol A may comprise the largest amount of the aromatic hydrocarbon compounds (specifically, phenolic compounds). For example, its content may be greater than 30% by weight, or greater than 50% by weight, based on the total amount of the phenolic compounds. When the composition of the base resin containing aromatic hydrocarbon compounds (specifically, phenolic compounds) and containing bisphenol A within the aforementioned content range is as described above, it can be easily recovered and reused through separation, filtration, and purification.

[0042] For example, the pre-treated fiber composite material can be a crushed or cut fiber composite material. Crushing and cutting the fiber composite material used for decomposition using superheated steam into a specified size and shape for use in the process can help prevent the degradation of the physical properties of the resulting regenerated fiber. For example, the crushing method includes a shredder, a shredder, a crushing mill, a hammer mill, etc., which can crush the fiber composite material into a specified size range. However, the size of the crushed composite material is uneven and a large amount of dust and powder is generated. Therefore, the effect of preventing the quality and yield of the recycled carbon fiber from being reduced by half, and the operating environment is also deteriorated. However, the fiber composite material produced using a cutting machine generates less dust and powder as described above, thereby increasing the yield and being able to be cut into a specified size. Therefore, the fiber length of the recycled carbon fiber, such as the recycled carbon fiber, is relatively uniform, and regenerated fiber with minimized quality degradation can be obtained. That is, in the pre-treatment, cutting is more conducive to preventing the degradation of the physical properties of the regenerated fiber than crushing.

[0043] After being put into the material box, the pre-treated fiber composite material automatically moves and is exposed to superheated steam and oxidant (specifically, the superheated steam and oxidant are sequentially sprayed into the automatically moving material box), whereby the pre-treated fiber composite material decomposes.

[0044] For example, according to the method for producing regenerated fibers of the present invention, the decomposition rate of the fiber composite material is very excellent. Here, the decomposition rate is a numerical value as shown in Mathematical Formula 1.

[0045] Mathematical formula 1: Decomposition rate (wt%) = {(A-B) / (A×C)}×100 In the above mathematical formula 1, A is the weight of the fiber composite material before decomposition (g), B is the weight of the decomposed fiber composite material (g), C is the content (wt %) of the matrix resin in the fiber composite material based on the total amount of the fiber composite material before decomposition.

[0046] The superheated steam injected into the magazine containing the pretreated fiber composite material can be injected using a superheated steam generator. For example, superheated steam heated to a temperature of 400°C to 900°C, 400°C to 800°C, 500°C to 900°C, or 500°C to 800°C can be used. A temperature of less than 400°C causes a sharp decrease in the decomposition rate, while a temperature exceeding 900°C is not preferred because the tensile strength of the recovered (produced) regenerated fiber decreases.

[0047] For example, superheated steam in the temperature range can be sprayed into the cartridge for 30 to 120 minutes, 30 to 110 minutes, 30 to 100 minutes, or 30 to 90 minutes. Spraying superheated steam in the temperature range for less than 30 minutes can lead to a sharp drop in the decomposition rate. Spraying superheated steam in the temperature range for more than 120 minutes can significantly reduce the decomposition rate and decrease the tensile strength. Therefore, exposing the pre-treated fiber composite material to superheated steam in the temperature range for more than 120 minutes is uneconomical.

[0048] For example, superheated steam within the above temperature range can be sprayed into the cartridge at a flow rate of 10 kg / h to 30 kg / h, 10 kg / h to 25 kg / h, or 10 kg / h to 20 kg / h within the above time range. A flow rate of less than 10 kg / h or greater than 30 kg / h is not preferred because the tensile strength of the produced regenerated fiber decreases.

[0049] Char, which is composed of trace amounts of carbon from the matrix resin decomposed from the fiber composite material by exposure to the superheated steam, may remain on the surface of the reinforcing material (carbon fiber and / or glass fiber). Based on the resin in the fiber composite material, the proportion of char produced is about 5% to 10% by weight. The char makes it impossible to separate the reinforcing material separately, but it is manufactured into a lump form. The reinforcing material containing char has low flexibility and will constitute impurities in subsequent processes. Therefore, it needs to be removed. The char is a carbon material and is difficult to remove only by superheated steam in an inert atmosphere. An oxidant can be added to remove it. The oxidant can be an active gas such as air or oxygen.

[0050] Specifically, the reinforcement material containing the char is moved into a cartridge, after which air is automatically injected into the cartridge containing the char. This continuous process, i.e., by injecting additional air, allows the char to be removed. Removing the char requires high temperatures and an appropriate air flow rate. Low temperatures or low air flow rates prevent the char from being removed. Excessively high temperatures or high air flow rates, while completely removing the char, can damage the reinforcement material, degrading its properties. Therefore, appropriate temperature, duration, and air flow rates are crucial. Treatment can be performed within the range of 400°C to 900°C, for 10 to 90 minutes, and at an air flow rate of 5 L / min or more to remove the char. Preferably, treatment can be performed within the range of 500°C to 800°C, for 30 to 60 minutes, and at an air flow rate of 5 L / min. In particular, even if the temperature and duration of the injected air are controlled within the aforementioned ranges, the decomposition rate improvement effect is insignificant if the air flow rate is less than 5 L / min.

[0051] If the char is not removed, it will become an impurity, reducing the decomposition rate. Therefore, it is preferable to remove it. However, when the char is removed by injecting air as described above, while the decomposition rate can be improved, there is a problem that the tensile strength retention and elasticity retention of the regenerated fiber finally recovered may be slightly reduced. To solve this problem, the flow rate of the injected air is controlled in the regenerated fiber production method of the present invention.

[0052] Furthermore, the regenerated fiber production method of the present invention may further include the following step: after placing the pre-treated fiber composite material into the hopper, prior to exposing the hopper to the superheated steam, exposing the hopper to nitrogen gas; or, after producing the regenerated fiber, prior to moving the hopper containing the regenerated fiber, exposing the hopper to nitrogen gas. This step is more conducive to preventing the tensile strength retention and elasticity retention of the recycled regenerated fiber from decreasing.

[0053] In this way, the reinforcement material, from which the char has been removed, is automatically transported into a magazine. By collecting the reinforcement material (regenerated fiber) from the magazine, regenerated fiber can be produced. The weight of the recovered regenerated fiber is measured, and the decomposition rate and yield are ultimately calculated to verify the physical properties of the regenerated fiber.

[0054] The tensile strength of the regenerated fiber (reinforcement material) can be measured using the single fiber method (ASTM C1557-03). In this method, a piece of reinforcement material at least 25 mm in length is separated and measured at least 30 times using a universal testing machine (UTM) at a testing speed of 1 mm / min, a grip spacing of 25 mm, and an initial load of 1 cN / tex. The average value is then calculated.

[0055] According to the regenerated fiber manufacturing method of the present invention, i) the fiber composite material is pre-treated before use, ii) a series of automatic processes using a material box push method are adopted, which is significantly different from the existing roller process, iii) cooling water is used to condense the gaseous matrix resin into a liquid for removal, which is also different from the existing process using external air, iv) the temperature, time and flow rate of the superheated steam in the superheated steam exposure part are controlled, and v) the temperature, time and flow rate of the air in the resin removal part are controlled. As a result, not only can the regenerated fiber with minimized physical property degradation be recovered, but the matrix resin in the form of condensed water can also be easily obtained, so it is environmentally friendly, and compared with the existing regenerated fiber recycling method, the processability and economy are very excellent.

[0056] Implementation Method Below, preferred embodiments are given to help understand the present invention. The following embodiments are only used to illustrate the present invention. Those skilled in the art can make various changes and modifications within the scope of the scope of the present invention and the technical concept, and these variations and modifications fall within the scope of the appended claims.

[0057] Experimental example 1. Effect of superheated steam temperature 130g of hydrogen tank cut pieces (50mm x 100mm) were placed in a cartridge in the inlet of an automatic regenerated fiber production device using a push-type cartridge feed method. The cartridge was then moved to expose it to superheated steam. The discharge temperature of the superheated steam was varied as shown in Table 1, and the decomposition rate and physical properties of the recovered carbon fiber were evaluated. The results are shown in Table 1. After the superheated steam was injected, the cartridge was moved again and air was injected to expose it to air. The air flow rate was controlled to 5L / min. After the superheated steam was injected and before the air was injected, the matrix resin decomposed from the hydrogen tank cut pieces in the cartridge that had been injected with superheated steam was condensed and removed using cooling water. After the air was injected, the cartridge was moved, and carbon fiber was recovered from it.

[0058] Table 1: From Table 1, it can be confirmed that when the discharge temperature of the superheated steam is controlled within a range of 400° C. to 900° C., both the decomposition rate and the tensile strength of the recovered regenerated fiber are excellent.

[0059] 2. Effect of superheated steam flow rate The same procedure as in Experimental Example 1 was carried out except that the flow rate of superheated steam was changed from 20 kg / h to the steam amount shown in Table 2. The results are shown in Table 2.

[0060] Table 2: It can be confirmed from Table 2 that when the flow rate of superheated steam is controlled within a range of 10 kg / h to 30 kg / h, both the decomposition rate and the tensile strength of the recovered regenerated fiber are excellent.

[0061] 3. Effect of exposure time based on superheated steam The same procedure as in Experimental Example 1 was carried out except that the exposure time to superheated steam was changed from 90 minutes to the time shown in Table 3. The results are shown in Table 3.

[0062] Table 3: From Table 3, it can be confirmed that when the exposure time to superheated steam is controlled within a range of 30 minutes to 120 minutes, both the decomposition rate and the tensile strength of the recovered regenerated fiber are excellent.

[0063] 4. Effect based on air flow The same procedure as in Experimental Example 1 was carried out except that the air flow rate during exposure to air was changed from 5 L / min to the air flow rate shown in Table 4. The results are shown in Table 4.

[0064] Table 4: It can be confirmed from Table 4 that when not only the temperature, time, and flow rate of the superheated steam in the superheated steam exposure section but also the air flow rate in the air injection section are controlled within the prescribed range, both the decomposition rate and the tensile strength of the recovered regenerated fiber are excellent.

[0065] The above describes in detail several preferred embodiments of the present invention. However, the scope of the claims of the present invention is not limited thereto. Various modifications and improvements made by those skilled in the art using the basic concepts of the present invention defined in the scope of the appended claims also fall within the scope of the claims of the present invention.

Claims

1. A method for producing regenerated fiber, characterized in that: The steps include: Putting the pre-treated fiber composite material into the material box; Moving the material box containing the pre-treated fiber composite material; exposing the cartridge to superheated steam and an oxidant; removing matrix resin and char from the pretreated fiber composite to produce regenerated fiber; as well as The cassette containing the regenerated fibers is moved and the regenerated fibers are collected from the cassette.

2. The method for producing regenerated fiber according to claim 1, wherein: The step of exposing the magazine to superheated steam and an oxidant comprises first exposing the magazine containing the pretreated fiber composite material to superheated steam, and then moving the magazine and exposing it to an oxidant.

3. The method for producing regenerated fiber according to claim 2, wherein: Further comprising the steps of: After the magazine containing the pre-treated fiber composite material is exposed to superheated steam, cooling water is used to condense the gaseous matrix resin decomposed from the pre-treated fiber composite material into liquid for removal before the magazine is exposed to the oxidant.

4. The method for producing regenerated fiber according to claim 3, wherein: The step of condensing the gaseous matrix resin decomposed from the pre-treated fiber composite material into a liquid state for removal is as follows: By being exposed to the superheated steam, the gaseous matrix resin decomposed from the pre-treated fiber composite material escapes from the cartridge and reacts with cooling water existing independently of the cartridge, thereby becoming liquid condensate and being removed.

5. The method for producing regenerated fiber according to claim 1, wherein: The oxidant includes air.

6. The method for producing regenerated fiber according to claim 1, wherein: The fiber composite material is formed by mixing carbon fiber, glass fiber or a mixture thereof with a matrix resin.

7. The method for producing regenerated fiber according to claim 6, wherein: The base resin comprises an aromatic hydrocarbon compound.

8. The method for producing regenerated fiber according to claim 7, wherein: The aromatic hydrocarbon compounds include phenol compounds.

9. The method for producing regenerated fiber according to claim 7, wherein: The aromatic hydrocarbon compound includes bisphenol A, and the content of the bisphenol A is greater than or equal to 30 wt % relative to the total amount of the aromatic hydrocarbon compound.

10. The method for producing regenerated fiber according to claim 1, wherein: The pre-treated fiber composite material is a crushed or cut fiber composite material.

11. The method for producing regenerated fiber according to claim 1, wherein: The temperature of the superheated steam ranges from 400°C to 900°C.

12. The method for producing regenerated fiber according to claim 1, wherein: The magazine containing the pretreated fiber composite material is exposed to the superheated steam for 30 to 120 minutes.

13. The method for producing regenerated fiber according to claim 1, wherein: The step of exposing to superheated steam includes the step of spraying the superheated steam toward the magazine containing the pretreated fiber composite material, wherein the superheated steam is sprayed toward the magazine at a flow rate of 10 kg / h to 30 kg / h.

14. The method for producing regenerated fiber according to claim 1, wherein: The step of exposing to the oxidant includes the step of spraying the superheated steam into the material box containing the pretreated fiber composite material and then spraying the oxidant into the material box, wherein the oxidant is sprayed into the material box at a flow rate of 5 L / min or more.

15. The method for producing regenerated fiber according to claim 1, wherein: Further comprising the steps of: After the step of placing the pre-treated fiber composite material into the magazine, the magazine is exposed to nitrogen before being exposed to the superheated steam.

16. The method for producing regenerated fiber according to claim 1, wherein: Further comprising the steps of: After the step of producing the regenerated fiber, the magazine containing the regenerated fiber is exposed to nitrogen before being moved.

17. The method for producing regenerated fiber according to claim 1, wherein: The charred matter exists on the surface of the regenerated fiber from which the matrix resin has been removed.

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