Method for regenerating carbon fiber bundle and regenerating apparatus of carbon fiber bundle

Abstract

To provide a regenerating method of carbon fiber bundles capable of shortening a heating time of a structure and a regeneration apparatus of carbon fiber bundles.SOLUTION: A method for regenerating carbon fiber bundles is a method of regenerating carbon fiber bundles from a high-pressure hydrogen tank T that has openings formed at both longitudinal ends. The method for regenerating carbon fiber bundles includes a suspension step in which the high-pressure hydrogen tank T is suspended by fixing the end with the opening to a position on the upper side in the vertical direction without closing the opening, a first heating step in which the suspended high-pressure hydrogen tank T is heated to decompose the matrix resin, an unwinding step in which an intermediate carbon fiber bundle with decomposition residues of the matrix resin adhered thereto is unwound from the carbon fiber reinforced resin layer from which the matrix resin has decomposed, a second heating step in which the unwound intermediate carbon fiber bundle is heated to decompose the decomposition residues of the matrix resin to obtain regenerated carbon fiber bundles, and a winding-up step in which the regenerated carbon fiber bundles are wound up.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a method and an apparatus for recycling carbon fiber bundles. [Background technology]

[0002] In recent years, efforts to significantly reduce waste generation through waste prevention, reduction, recycling, and reuse have become increasingly active. To achieve this, research and development is being conducted on methods for recovering carbon fiber from carbon fiber reinforced resins.

[0003] Patent Document 1 describes a tank recycling device that includes a liner, which is an inner shell, and a reinforcing layer formed of a carbon fiber reinforced plastic containing carbon fiber and a matrix component so as to cover the liner, with openings provided on both end sides of the liner. The tank recycling device includes a carbonization furnace that includes a carbonization chamber that houses the tank, a heating chamber that surrounds the carbonization chamber, and a combustion chamber that heats the heating chamber including the carbonization chamber, and a frame that stores the tank, with a hanging device attached to an opening located at the top. The frame also includes multiple pillar members that are longer than the tank and beam members that span the pillar members and to which the hanging devices are attached. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2020 / 179915 Summary of the Invention [Problem to be solved by the invention]

[0005] In this case, when the liner is made of resin, it is possible to use the tank recycling device of Patent Document 1, but a hanging device is attached to the opening at the top end of the tank, blocking the opening. This prevents water vapor from flowing in through the opening at the top end of the tank, making it difficult to dry distill the resin that makes up the liner. It also prevents gas generated by dry distillation of the resin from flowing out of the opening at the top end of the tank, resulting in a longer dry distillation time for the tank.

[0006] An object of the present invention is to provide a method and an apparatus for recycling carbon fiber bundles that can shorten the heating time of a structure. [Means for solving the problem]

[0007] [1] A method for recycling carbon fiber bundles from a structure having a hollow substrate and a carbon fiber reinforced resin layer containing carbon fiber bundles and a matrix resin wound around the hollow substrate, the structure having an opening formed in at least one end in the longitudinal direction, the method comprising: a hanging step of suspending the structure, which is positioned vertically upward without blocking the opening and by fixing the end where the opening is formed; a first heating step of heating the suspended structure to decompose the matrix resin; an unwinding step of unwinding an intermediate carbon fiber bundle having decomposition residues of the matrix resin adhering thereto from the carbon fiber reinforced resin layer where the matrix resin has been decomposed; a second heating step of heating the unwound intermediate carbon fiber bundle to decompose the decomposition residues of the matrix resin to obtain a recycled carbon fiber bundle; and a winding step of winding up the recycled carbon fiber bundle.

[0008] [2] The method for recycling carbon fiber bundles according to [1], wherein the hollow substrate contains a resin.

[0009] [3] The method for regenerating a carbon fiber bundle according to [1] or [2], wherein the suspended structure is heated in an oxygen-containing environment.

[0010] [4] The method for regenerating a carbon fiber bundle according to any one of [1] to [3], wherein a plurality of the structures are suspended and the suspended structures are heated.

[0011] [5] An apparatus for recycling carbon fiber bundles from a structure having a hollow substrate and a carbon fiber reinforced resin layer containing carbon fiber bundles and a matrix resin wound around the hollow substrate, the structure having an opening formed at at least one end in the longitudinal direction, the apparatus comprising: a hanging unit that is arranged vertically above the opening without blocking it and that suspends the structure by fixing the end where the opening is formed; a first heating unit that heats the structure fixed by the hanging unit to decompose the matrix resin; an unwinding unit that unwinds an intermediate carbon fiber bundle having decomposition residues of the matrix resin adhering thereto from the carbon fiber reinforced resin layer where the matrix resin has been decomposed; a second heating unit that heats the unwound intermediate carbon fiber bundle to decompose the decomposition residues of the matrix resin to obtain a recycled carbon fiber bundle; and a winding unit that winds up the recycled carbon fiber bundle.

[0012] [6] The carbon fiber bundle recycling device described in [5], wherein the hanging unit is arranged vertically above and has a jig that clamps the outer peripheral surface of the end where the opening is formed.

[0013] [7] The carbon fiber bundle recycling device described in [6], wherein the hanging section hangs the plurality of structures, and the jig clamps the outer peripheral surfaces of the ends of the plurality of structures where the openings are formed.

[0014] [8] The carbon fiber bundle recycling device described in [5], wherein the hanging section has a jig that is screwed into an opening located vertically above the jig, and the jig has a through hole formed in it so as not to block the opening.

[0015] [9] The carbon fiber bundle recycling device described in [8], wherein the hanging unit hangs a plurality of the structures and has a plurality of the jigs.

[0016]

[10] The carbon fiber bundle recycling device described in any one of [5] to [9], wherein the hanging section further has a plate-like member arranged to face and contact an end portion arranged on the vertically lower side of the structure, and the plate-like member has a through hole formed therein. [Effects of the Invention]

[0017] According to the present invention, it is possible to provide a method for recycling carbon fiber bundles and an apparatus for recycling carbon fiber bundles that can shorten the heating time of the structure. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 2 is a cross-sectional view showing an example of a high-pressure hydrogen tank with the mouthpiece removed. [Figure 2] FIG. 2 is a perspective view showing an example of a suspending unit for suspending the high-pressure hydrogen tank of FIG. 1. [Figure 3] FIG. 3 is a perspective view showing a modified example of the hanging portion of FIG. 2. [Figure 4] FIG. 4 is a partially enlarged cross-sectional view of the hanging portion of FIG. 3. [Figure 5] FIG. 4 is a diagram showing an example of a first heating section used in a first heating step. [Figure 6] FIG. 10 is a diagram showing an example of an unwinding unit used in an unwinding process. [Figure 7] FIG. 2 is a schematic view showing an example of a second heating section, a sizing section, and a winding section used in the second heating step, the sizing step, and the winding step. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0020] A method for recycling carbon fiber bundles according to one embodiment of the present invention is a method for recycling carbon fiber bundles from a structure having a hollow substrate, a carbon fiber reinforced resin layer containing carbon fiber bundles and a matrix resin wound around the hollow substrate, and an opening formed in at least one longitudinal end portion. The structure is not particularly limited, but examples thereof include known high-pressure hydrogen tanks (types 2 to 4) from which the mouthpiece has been removed.

[0021] The carbon fibers constituting the carbon fiber bundle are not particularly limited, but examples thereof include polyacrylonitrile (PAN)-based carbon fibers and pitch-based carbon fibers. Here, the carbon fibers constituting the carbon fiber bundle are long fibers. The fiber length of the carbon fibers is not particularly limited, but is, for example, 1 m or more. The matrix resin is not particularly limited, but examples thereof include cured products of thermosetting resins such as epoxy resins, and thermoplastic resins.

[0022] Figure 1 shows an example of a high-pressure hydrogen tank with the nozzle removed.

[0023] A high-pressure hydrogen tank T with its nozzle removed (hereinafter referred to as high-pressure hydrogen tank T) has a liner L as a hollow substrate, and a carbon fiber reinforced resin layer F containing carbon fiber bundles and a matrix resin wound around the liner L, with openings formed at longitudinal ends E1 and E2. The material constituting the liner L is not particularly limited, but examples include metals such as aluminum and chromium molybdenum steel, and resins such as polyamide and polyethylene.

[0024] The method for manufacturing the high-pressure hydrogen tank T is not particularly limited, but may be, for example, a filament winding method.

[0025] A method for recycling carbon fiber bundles according to one embodiment of the present invention includes a hanging step of suspending a high-pressure hydrogen tank T, which is positioned vertically upward without blocking the opening, by fixing the end E1 where the opening is formed, and a first heating step of heating the suspended high-pressure hydrogen tank T in a first environment containing oxygen to decompose the matrix resin. The method for recycling carbon fiber bundles according to one embodiment of the present invention further includes an unwinding step of unwinding an intermediate carbon fiber bundle I, to which decomposition residues of the matrix resin adhere, from a carbon fiber reinforced resin layer F where the matrix resin has been decomposed. The method for recycling carbon fiber bundles according to one embodiment of the present invention further includes a second heating step of heating the unwound intermediate carbon fiber bundle I in a second environment containing oxygen to decompose the decomposition residues of the matrix resin to obtain a recycled carbon fiber bundle R, and a winding step of winding the recycled carbon fiber bundle R.

[0026] In this specification and claims, "hanging a structure" includes a state in which the end portion located vertically below the structure is not in contact with other members, as well as a state in which the end portion is in contact with other members.

[0027] In the hanging process, the end E1 is fixed without blocking the opening formed in the end E1. At this time, the high-pressure hydrogen tank T is held so that the longitudinal direction of the high-pressure hydrogen tank T is approximately parallel to the vertical direction. For this reason, even if the liner L is made of resin, inflow of oxygen from the end E1 of the high-pressure hydrogen tank T is not suppressed in the first heating process, making the resin that makes up the liner L more susceptible to thermal decomposition. In addition, the outflow of decomposition gas from the resin that makes up the liner L from the end E1 of the high-pressure hydrogen tank T is not suppressed. As a result, the heating time of the high-pressure hydrogen tank T is shortened. Furthermore, because the end E2 of the high-pressure hydrogen tank T is not fixed, even if the jig that fixes the end E1 linearly expands due to heating, the strain imposed on the high-pressure hydrogen tank T is suppressed.

[0028] Furthermore, during the hanging step, the opening formed at the end E2 located on the vertically lower side of the high-pressure hydrogen tank T is not blocked. Therefore, even if the liner L is made of resin, in the first heating step, the inflow of oxygen from the end E2 of the high-pressure hydrogen tank T is not inhibited, and the outflow of the pyrolysis liquid of the resin that makes up the liner L from the end E2 of the high-pressure hydrogen tank T is not inhibited. As a result, the resin that makes up the liner L is more easily pyrolyzed, and the high-pressure hydrogen tank T is less likely to deform. Furthermore, because the matrix resin is pyrolyzed evenly in the thickness direction of the carbon fiber reinforced resin layer F, the content of decomposition residue of the matrix resin in the intermediate carbon fiber bundle I is made uniform.

[0029] Here, when the content of the decomposition residue of the matrix resin in the intermediate carbon fiber bundle I is adjusted to a predetermined range, damage to the intermediate carbon fiber bundle I is suppressed when the intermediate carbon fiber bundle I to which the decomposition residue of the matrix resin adheres is unwound from the carbon fiber reinforced resin layer in which the matrix resin has been decomposed. The content of the decomposition residue of the matrix resin in the intermediate carbon fiber bundle I is, for example, 5% by weight or more and 10% by weight or less.

[0030] It is also possible to hang a plurality of high-pressure hydrogen tanks T in the hanging step, and heat the hung plurality of high-pressure hydrogen tanks T in the first heating step.

[0031] The first heating part used in the first heating step may be, for example, a hot air circulation oven or a gas oven.

[0032] In the first heating step, the high-pressure hydrogen tank T may be heated with superheated steam. In the second heating step, the intermediate carbon fiber bundle I may be heated with superheated steam.

[0033] FIG. 2 shows an example of a suspending unit for suspending a high-pressure hydrogen tank T.

[0034] The suspension unit 100 includes a jig 101 that clamps the outer peripheral surfaces of the ends E1 of multiple high-pressure hydrogen tanks T that are arranged vertically above each other, a beam member 102, a girder member 103, and a columnar member 104. Here, the jig 101 is composed of multiple U-shaped clamping portions 101a and rod-shaped portions 101b that are arranged on both sides of the clamping portions 101a. At this time, the rod-shaped portions 101b are fixed to the beam member 102 by, for example, bolts and nuts. The beam member 102 is bridged between opposing girder members 103, and the girder member 103 is bridged between adjacent columnar members 104.

[0035] The suspending unit 100 further includes a plate-like member 105 that is arranged to face and contact the end E2 that is arranged on the vertically lower side of the high-pressure hydrogen tank T, and the plate-like member 105 has a through-hole formed therein. The plate-like member 105 is supported by columnar members 104. Also, a tray is arranged below the plate-like member 105 into which the pyrolysis liquid of the resin that constitutes the liner L flows.

[0036] The plate-like member 105 is not particularly limited as long as it has through holes that do not prevent the pyrolysis liquid of the resin that makes up the liner L from flowing out of the end E2 of the high-pressure hydrogen tank T, but examples include wire mesh and punched metal.

[0037] The suspending unit 100 may have a jig 101 that clamps the outer peripheral surface of the end E1 located on the vertically upper side of a single high-pressure hydrogen tank T. The beam-shaped member 102 may have a U-shaped area facing the clamping unit 101a. Furthermore, the plate-shaped member 105 may be disposed at a predetermined distance from the end E2 located on the vertically lower side of the high-pressure hydrogen tank T.

[0038] FIG. 3 shows a modified example of the hanging part 100.

[0039] The hanging part 200 has a jig 201 that is screwed into an opening formed in the end E1 located vertically above each high-pressure hydrogen tank T instead of the jig 101, and has the same configuration as the hanging part 100 except that the jig 201 is supported by beam-shaped members 102 and 202.

[0040] 4, the jig 201 comprises a hollow disk-shaped substrate portion 201a and a cylindrical threaded portion 201b extending from the inner periphery of the substrate portion 201a, with a through-hole H formed in the center. The outer diameter of the threaded portion 201b is approximately the same as the inner diameter of the opening formed in the end E1 of the high-pressure hydrogen tank T. At this time, the substrate portion 201a is fixed to the beam-like members 102 and 202, for example, by bolts and nuts.

[0041] Hanging unit 200 may have a single jig 201. Beam member 202 may be a movable beam member that rotates around beam member 102 as a fulcrum.

[0042] FIG. 5 shows a heat treatment furnace as an example of the first heating section used in the first heating step.

[0043] The heat treatment furnace 10 has a heat treatment chamber 11 and a combustion chamber 12 .

[0044] The heat treatment chamber 11 is an enclosed space surrounded by an outer wall 11a and an inner wall 11b. In addition, the heat treatment chamber 11 is provided with burners 11c at the top of the outer wall 11a on the left side and at the bottom of the outer wall 11a on the right side in the drawing so that combustion gas flows into the inner wall 11b. Therefore, when gas fuel and air are mixed and burned in the burner 11c, the combustion gas convects within the inner wall 11b, stabilizing the temperature within the inner wall 11b.

[0045] The heat treatment chamber 11 has sealed doors installed on parts of the outer wall 11a and inner wall 11b to accommodate the high-pressure hydrogen tank T suspended by the suspension unit 100. The high-pressure hydrogen tank T is placed on a heat insulating material 11d that penetrates the bottom surface of the inner wall 11b. A load cell 11e serving as a mass detector is installed between the bottom surface of the outer wall 11a and the heat insulating material 11d and detects the mass of the high-pressure hydrogen tank T in real time based on the amount of strain. This optimizes the heating conditions in the heat treatment chamber 11, suppressing variations in the amount of decomposition of the matrix resin due to individual differences in the material, shape, etc., that make up the high-pressure hydrogen tank T, and improving management accuracy. Furthermore, since the heating time in the heat treatment chamber 11 does not need to be longer than necessary, this contributes to shortening the heating time and reducing energy consumption.

[0046] The mass detector may detect in real time the amount of mass loss of the high-pressure hydrogen tank T. Also, the mass detector may be omitted as necessary.

[0047] The decomposition gas of the matrix resin generated within the inner wall 11b is discharged from an exhaust port 11f formed at the top of the inner wall 11b in the figure, and then introduced into the combustion chamber 12 via a pipe 11g installed to penetrate the outer wall 11a.

[0048] The combustion chamber 12 is a sealed space surrounded by an outer wall 12a and an inner wall 12b. A burner 12c is provided in the center of the outer wall 12a (left side of the figure) so that combustion gas flows into the inner wall 12b. The pipe 11g penetrates the outer wall 12a, then penetrates the inside and outside of the inner wall 12b within the outer wall 12a, and finally connects to the upper left of the inner wall 12b. The decomposition gas of the matrix resin is heated by the combustion gas flowing through the inner wall 12b while passing through the pipe 11g inside the inner wall 12b, and then introduced from the upper left of the inner wall 12b and comes into contact with the combustion gas. After combustion, the decomposition gas of the matrix resin is exhausted to the outside through the exhaust port 12d.

[0049] The heat treatment furnace 10 may further include a pipe for supplying the exhaust heat from the combustion chamber 12 to the tubular furnace 40, which will be described later.

[0050] An example of an unwinding unit used in the unwinding process is shown in Figure 6. Figures 6(a) and 6(b) are a front view and a side view, respectively.

[0051] The unwinding section 30 has a rotating jig 31 that rotatably supports the high-pressure hydrogen tank T1 in which the matrix resin has been decomposed, and a motor 32 that rotates the high-pressure hydrogen tank T1. The rotational power of the motor 32 is transmitted to the rotating jig 31 via a belt 33. As a result, the intermediate carbon fiber bundle I is unwound via rollers 34, 35, and 36. At this time, the roller 34 is positioned so that the intermediate carbon fiber bundle I is unwound outside the tangent line at the position where the intermediate carbon fiber bundle I is unwound from the high-pressure hydrogen tank T1. Furthermore, the rollers 34, 35, and 36 have long axes that correspond to the unwinding of the intermediate carbon fiber bundle I in the longitudinal direction of the high-pressure hydrogen tank T1. Furthermore, a dancer roller 37 that controls the unwinding tension is installed to absorb the difference in the unwinding amount per rotation between hoop winding and helical winding of the intermediate carbon fiber bundle I.

[0052] Instead of the roller 34, a blade may be provided.

[0053] Furthermore, after a sizing step of sizing the recycled carbon fiber bundle R is carried out, the sized recycled carbon fiber bundle R may be unwound.

[0054] FIG. 7 shows an example of the second heating section, sizing section, and winding section used in the second heating step, sizing step, and winding step.

[0055] A tubular furnace 40 serving as a second heating section has a quartz tube 41 and, at both ends thereof, insulating covers 42 formed with through-holes through which the intermediate carbon fiber bundle I having the decomposition residue of the matrix resin attached thereto can pass. The tubular furnace 40 also has an electric wire heater 43, an insulating material 44, and a protective cover 45 sequentially disposed in the center of the quartz tube 41. Therefore, the electric wire heater 43 heats the intermediate carbon fiber bundle I, decomposing the decomposition residue of the matrix resin, and thus a recycled carbon fiber bundle R is obtained. At this time, the temperature distribution within the tubular furnace 40 is made uniform, and heating of parts other than the intermediate carbon fiber bundle I is suppressed.

[0056] The sizing unit 50 passes the recycled carbon fiber bundle R through a sizing liquid 51. At this time, the sizing liquid 51 is heated by a heater 52. In addition, a roller 53 prevents the sizing liquid 51 from being applied excessively to the recycled carbon fiber bundle R.

[0057] If necessary, a drying oven may be installed to dry the recycled carbon fiber bundle R.

[0058] The feeding mechanism 60 has feeder rollers 61, 62, and 63, and by utilizing friction between the feeder rollers 61, 62, and 63 and the recycled carbon fiber bundle R, the linear speed of the recycled carbon fiber bundle R is controlled to a linear speed that is easy to manage in the process.

[0059] The winding section 70 includes a winding motor 71 for winding the recycled carbon fiber bundle R around the paper core P, and a slide roller 72 for traverse-winding the recycled carbon fiber bundle R. At this time, the winding tension of the recycled carbon fiber bundle R is controlled by controlling the torque of the winding motor 71.

[0060] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and the above-described embodiments may be modified as appropriate within the scope of the spirit of the present invention. [Explanation of symbols]

[0061] 100, 200 Hanging part 101, 201 Jig 101a Clamping part 101b Rod-shaped part 102, 202 Beam-like members 103 Girder-like members 104 Columnar Members 201a Base material part 201b Threaded part E1, E2 ends F Carbon fiber reinforced resin layer H through hole I. Intermediate carbon fiber bundle L Liner R Recycled carbon fiber bundle T, T1 high-pressure hydrogen tank

Claims

1. A method for regenerating carbon fiber bundles from a structure having a hollow substrate and a carbon fiber reinforced resin layer containing carbon fiber bundles and a matrix resin wound around the hollow substrate, the structure having an opening formed at at least one end in a longitudinal direction, the method comprising: a hanging step of suspending the structure by fixing an end portion of the structure disposed vertically above the opening without closing the opening and in which the opening is formed; a first heating step of heating the suspended structure to decompose the matrix resin; an unwinding step of unwinding an intermediate carbon fiber bundle having decomposition residues of the matrix resin attached thereto from the carbon fiber reinforced resin layer in which the matrix resin has been decomposed; a second heating step in which the unwound intermediate carbon fiber bundle is heated to decompose the decomposition residue of the matrix resin, thereby obtaining a recycled carbon fiber bundle; a winding step of winding the recycled carbon fiber bundle.

2. The method for recycling carbon fiber bundles according to claim 1 , wherein the hollow substrate contains a resin.

3. 3. The method for regenerating carbon fiber bundles according to claim 1 or 2, wherein the suspended structure is heated in an oxygen-containing environment.

4. Suspending a plurality of the structures; The method for regenerating carbon fiber bundles according to claim 1 or 2, wherein the suspended structures are heated.

5. An apparatus for recycling carbon fiber bundles from a structure having a hollow substrate and a carbon fiber reinforced resin layer containing carbon fiber bundles and a matrix resin wound around the hollow substrate, the structure having an opening formed at at least one end in a longitudinal direction, the apparatus comprising: a hanging portion that is disposed vertically above the opening without closing the opening and that fixes the end portion where the opening is formed to hang the structure; and a first heating section that heats the structure fixed by the hanging section to decompose the matrix resin; an unwinding section that unwinds an intermediate carbon fiber bundle having decomposition residues of the matrix resin attached thereto from the carbon fiber reinforced resin layer in which the matrix resin has been decomposed; a second heating section for heating the unwound intermediate carbon fiber bundle to decompose the decomposition residue of the matrix resin and obtain a recycled carbon fiber bundle; a winding section for winding the recycled carbon fiber bundle.

6. The carbon fiber bundle recycling device according to claim 5 , wherein the hanging unit is disposed on the upper side in the vertical direction and has a jig that clamps the outer peripheral surface of the end portion where the opening is formed.

7. the hanging unit hangs the plurality of structures; The carbon fiber bundle recycling device according to claim 6 , wherein the jig clamps the outer peripheral surfaces of the ends of the plurality of structures where the openings are formed.

8. the hanging portion has a jig that is screwed into an opening disposed on the upper side in the vertical direction, The carbon fiber bundle recycling device according to claim 5 , wherein the jig has a through hole formed therein so as not to block the opening.

9. The carbon fiber bundle recycling device according to claim 8 , wherein the hanging unit hangs a plurality of the structures and has a plurality of the jigs.

10. the hanging portion further includes a plate-like member arranged to face and contact an end portion of the structure arranged on a vertically lower side thereof, The carbon fiber bundle recycling device according to claim 5 , wherein the plate-like member has a through hole formed therein.

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