Method for recycling reinforcement fiber

Abstract

To provide a method for easily recycling reinforcement fibers from a tank.SOLUTION: A method for recycling reinforcement fibers of the embodiment includes the steps of: preparing a tank having at least a liner, a first protective layer disposed on an outer peripheral surface of the liner and configured so that a resin-impregnated fiber bundle containing a reinforcing fiber bundle and a first matrix resin is wound around the liner, and a second protective layer formed on the first protective layer and composed of the first matrix resin; removing a portion of the second protective layer to expose a winding end of the resin-impregnated fiber bundle; peeling off the exposed end of the winding; and pulling the peeled end of the winding to pull out the resin-impregnated fiber bundle.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a method for recycling reinforcing fibers. [Background technology]

[0002] Carbon fiber reinforced plastic (CFRP) is lightweight and highly rigid. It is a material that can withstand high pressure gas. Therefore, it is used in hydrogen tanks for fuel cell (FC) vehicles. It is also used as a reinforcing material in applications such as: (GFRP: Glass Fiber Reinforced Plastic) layer is placed as a protective material Fiber-reinforced plastics are also used.

[0003] As a tank in which a carbon fiber reinforced resin layer and a glass fiber reinforced resin layer are arranged, for example, Patent Document 1 describes a gas separator that includes a resin liner that contains gas and a carbon fiber liner that covers the outer surface of the liner. a reinforcing layer made of a fiber-reinforced resin having a reinforcing fiber of glass fiber, and a glass fiber A high-pressure tank for gas storage having at least a protective layer made of fiber-reinforced resin with the reinforced fiber The protective layer covers the outer peripheral surface of the reinforcing layer and is made of glass fiber and a matrix resin. a first protective layer made of a fiber reinforced resin and covering an outer peripheral surface of the first protective layer; and a second protective layer containing the matrix resin, The content of the matrix resin in the reinforcing layer is lower than the content of the matrix resin in the second protective layer. The first and second protective layers extend from the surface of the second protective layer so as to surround the pressure tank. 2. A high-pressure gas storage device characterized by the formation of cracks reaching the interface with the protective layer. Specifically, the high-pressure tank disclosed in Patent Document 1 is made of carbon fiber. A reinforcing layer made of fiber-reinforced resin and a glass fiber covering the outer periphery of the reinforcing layer. and a protective layer made of a fiber-reinforced resin having reinforcing fibers, the protective layer being formed on the outer peripheral surface of the reinforcing layer. a first protective layer made of a fiber-reinforced resin composed of glass fiber and a matrix resin; a second protective layer covering the outer peripheral surface of the first protective layer and containing the matrix resin. do.

[0004] However, the carbon fibers and glass fibers contained in the carbon fiber reinforced resin or the glass fiber reinforced resin Fibers are expensive, emit a large amount of CO2 during production, and are difficult to dispose of, making them environmentally friendly. Therefore, carbon fiber and glass fiber are recovered from used fiber reinforced resin and recycled. Cycling methods are being considered.

[0005] Patent document disclosing a method for recycling reinforcing fibers such as carbon fiber and glass fiber from tanks Examples of such documents include the following Patent Documents 2 and 3.

[0006] Patent Document 2 describes an unwinding machine that unwinds reinforced fibers while separating resin from reinforced parts. A step of passing the reinforcing fibers through a sizing solution to apply the sizing solution to the reinforcing fibers. The sizing stage involves coating the reinforcement fiber with the sizing solution, and winding the coated reinforcement fiber around a mandrel. and a winding step of removing the reinforcing fibers. Patent Document 1 describes a method for strengthening a reinforced part by immersing the reinforced part in a swelling liquid in the unwinding stage. The swelling stage involves swelling the resin of the reinforced parts, and the reinforcing fibers are then fed out of the reinforced parts and immersed in the solution. The dissolving stage dissolves the resin impregnated in the reinforcing fibers, and the reinforcing fibers with the dissolved resin are and an intermediate winding step of winding the .

[0007] Patent Document 3 discloses a carbon fiber reinforced resin composite including a plurality of carbon fiber substrates and a matrix resin. The carbon fiber substrate is obtained as a recycled carbon fiber bundle, and the carbon fiber reinforced resin is heated. The matrix resin is thermally decomposed to obtain a heat-treated product, and the heat-treated product a method for producing a recycled carbon fiber bundle, the method comprising: crushing the carbon fiber bundle to separate the plurality of carbon fiber base materials; has disclosed. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Publication No. 2020-37978 [Patent Document 2] Japanese Patent Application Laid-Open No. 2017-104847 [Patent Document 3] International Publication No. 2018 / 212016 Summary of the Invention [Problem to be solved by the invention]

[0009] For example, as disclosed in Patent Document 1, a liner and a The reinforced fiber bundles and the resin-impregnated fiber bundles containing the matrix resin are wound around the liner. a first protective layer formed of the matrix resin; and a second protective layer formed of the matrix resin on the first protective layer. There is a tank having at least two protective layers, and the reinforcing fibers from such a tank There is a need for recovery, or recycling, methods.

[0010] In order to recycle the reinforcing fibers from the tank, the following method is proposed as described in Patent Document 2: As shown above, if the reinforced part is immersed in swelling liquid before pulling out the reinforcing fiber, the end of winding the fiber-reinforced resin For example, the position of the dividing edge of the tank may be difficult to see. The display showing the end position may disappear or become difficult to see. The process of immersing the entire ink is complicated in terms of the use of swelling liquid, equipment, immersion time, etc. There are cases where this happens.

[0011] In order to recycle the reinforcing fibers from the tank, a method as described in Patent Document 3 has been proposed. If the entire tank is heated to thermally decompose the matrix resin, the tank will lose its shape. This may cause the reinforcing fibers to become unable to be drawn out continuously, and the resin impregnation may It may be difficult to determine the position of the winding end of the fiber bundle. The matrix resin is thermally decomposed by heating the carbon fiber reinforced resin at high temperatures. High temperature heating can cause the reinforcing fibers to deteriorate, resulting in a loss of strength. When the impregnated fiber bundle is heated at high temperatures, the properties of the resin, such as its solubility, change, making it difficult to remove the resin in the subsequent process. This may be the case.

[0012] Therefore, the purpose of the present disclosure is to solve at least one of the above problems, and specifically The reinforced fiber bundle and the resin-impregnated fiber bundle containing the matrix resin are wound around the liner. a first protective layer formed of the matrix resin on the first protective layer; A method for easily recycling reinforcing fibers from a tank having at least the second protective layer. The purpose is to provide the law. [Means for solving the problem]

[0013] One aspect of this embodiment is as follows. (1) A method for recycling reinforcing fibers, comprising: a liner, and a reinforcement fiber bundle and a first matrix disposed on the outer peripheral surface of the liner; a first protective layer configured such that a resin-impregnated fiber bundle containing a resin is wound around a liner; a second protective layer formed of the first matrix resin on the protective layer; providing a tank having removing a portion of the second protective layer to expose the winding end of the resin-impregnated fiber bundle; peeling the exposed end of the winding; and The process of pulling the peeled end of the winding and pulling out the resin-impregnated fiber bundle. A method comprising: (2) The second protective layer is formed by partially bleeding the first matrix resin contained in the first protective layer. The method according to (1), wherein the layer is formed by curing the layer in an extruded state. (3) The method according to (1) or (2), wherein the first matrix resin is an epoxy resin. Law. (4) Any of (1) to (3), wherein a part of the second protective layer is removed by laser treatment. or one of the methods described above. (5) The laser used for laser processing is a carbon dioxide laser, a YAG laser, a fiber laser, The method according to (4), wherein the laser is a laser diode or a semiconductor laser. (6) The method according to (5), wherein the laser used in the laser treatment is a carbon dioxide laser. (7) The method according to (6), wherein the output of the carbon dioxide laser is 100 W or less. (8) A portion of the second protective layer is removed by contacting a dissolving solution with the portion of the second protective layer. The method according to any one of (1) to (3), wherein the compound is removed. (9) The dissolving solution is selected from an acidic solution, an organic solvent, a hydrogen peroxide solution, and an ionic liquid. The method according to (8), comprising at least one liquid. (10) A part of the second protective layer is removed by heat treating the part of the second protective layer. The method according to any one of (1) to (3), (11) The method according to (10), wherein the temperature of the heat treatment is 550°C or higher and 700°C or lower. . (12) Any of (1) to (11), wherein the reinforcing fiber bundles are glass fiber bundles or carbon fiber bundles. The method according to any one of the following: (13) The method according to (12), wherein the reinforcing fiber bundles are glass fiber bundles. (14) Between the protective layer and the liner, a resin containing carbon fiber bundles and a second matrix resin is provided. (13) further comprising a reinforcing layer configured such that impregnated carbon fiber bundles are wound around the liner; The method described below. [Effects of the Invention]

[0014] According to the present disclosure, at least one of the above-mentioned problems can be solved, and specifically, The resin-impregnated fiber bundle containing the matrix resin and the resin-impregnated fiber bundle are wound around the liner. a first protective layer made of the matrix resin and a second protective layer made of the matrix resin on the first protective layer; and a protective layer. It is possible. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a flowchart illustrating one embodiment of a recycling method according to the present embodiment. [Figure 2] FIG. 1 is a schematic cross-sectional view showing an example of the configuration of a tank 100 that can be used in this embodiment, taken along a plane along the axial direction. [Figure 3]FIG. 3 is a schematic diagram showing a state in which the second protective layer 30b constituting the surface of the tank 100 shown in FIG. 2 has been partially removed to expose the first protective layer 30a. [Figure 4] FIG. 4 is an enlarged schematic view of the area surrounded by the dotted line in FIG. 3, showing the exposed winding end of the resin-impregnated fiber bundle. [Figure 5] 1 is a schematic diagram showing the shape of the winding end of a resin-impregnated fiber bundle in which the winding end is cured or solidified and fixed without being bent. FIG. [Figure 6] This is an image showing the state after removing the epoxy resin as the second protective layer with a low-power (average power: 30 W) carbon dioxide laser (10.6 μm, continuous wave). [Figure 7] 1 is a graph showing the relationship between the number of laser irradiations and etching depth (mm) when an epoxy resin serving as a second protective layer is removed using a low-power (average power: 30 W) carbon dioxide laser (10.6 μm, continuous wave). [Figure 8] 8 shows images of the tank surface at the 10th, 20th, and 50th irradiations in the experiment shown in FIG. 7. [Figure 9] 1 is a schematic diagram showing one embodiment of a tank having a bent portion at the winding end of the resin-impregnated fiber bundle, where the resin-impregnated fiber bundle is fixed in a bent state. FIG. [Figure 10] FIG. 1 is a schematic diagram illustrating the problem of vertical tearing of the fiber bundle that can occur when peeling off the winding end using a tool such as a scraper. [Figure 11] FIG. 1 is a schematic diagram illustrating the problem of tearing of the fiber bundle in the left-right direction, which may occur when peeling off the winding end using a tool such as a scraper. [Figure 12] FIG. 10 is a schematic diagram showing a configuration in which the resin-impregnated fiber bundle in the rear portion of the bent portion is bent and fixed so as to be on top of the resin-impregnated fiber bundle in the front portion of the bent portion. [Figure 13] FIG. 10 is a schematic diagram showing a configuration in which the resin-impregnated fiber bundle in the rear portion of the bent portion is bent and fixed so as to be below the resin-impregnated fiber bundle in the front portion of the bent portion. [Figure 14] FIG. 10 is a schematic diagram showing a configuration in which the resin-impregnated fiber bundle in the rear portion of the bent portion is folded back and fixed so as to be on top of the resin-impregnated fiber bundle in the front portion of the bent portion. [Figure 15] FIG. 10 is a schematic diagram showing a configuration in which the resin-impregnated fiber bundle in the rear portion of the bent portion is folded back and fixed so as to be below the resin-impregnated fiber bundle in the front portion of the bent portion. [Figure 16] 10 is a schematic diagram for explaining the bending angle θ, showing the bending portion viewed in the radial direction from outside the tank. FIG. [Figure 17] 10A and 10B are schematic diagrams for explaining a drawing step under heating in the present embodiment. [Figure 18A] FIG. 1 is a graph showing an example of the thermal properties of an epoxy resin, and is a graph showing a weight change chart (TG curve) of thermogravimetric analysis obtained by heating the resin under a nitrogen atmosphere (horizontal axis: temperature, vertical axis: weight loss rate). [Figure 18B] FIG. 1 is a graph showing an example of the thermal properties of an epoxy resin, and is a graph showing a weight change chart (TG curve) of thermogravimetric analysis obtained by heating the resin in an air atmosphere (horizontal axis: temperature, vertical axis: weight loss rate). [Figure 19] 1 is a graph showing the thermal properties of carbon fiber as an example of reinforcing fiber, and is a graph showing the strength ratio (tensile strength after heating / tensile strength before heating) when carbon fiber is heated in the atmosphere at predetermined temperatures (300°C, 400°C, 500°C) for predetermined times (horizontal axis). [Figure 20] 1 is a graph showing the tensile shear strength ratio of a resin (epoxy resin) at a predetermined temperature. [Figure 21] FIG. 21 is a schematic diagram for explaining the configuration of a test piece used in a tensile shear test for measuring the tensile shear strength ratio shown in FIG. 20. DETAILED DESCRIPTION OF THE INVENTION

[0016] This embodiment is a method for recycling reinforcing fibers, which includes a liner and the outer periphery of the liner. The reinforcing fiber bundles and the resin-impregnated fiber bundles containing the first matrix resin are arranged on the peripheral surface. a first protective layer configured to be wound around the inner layer; and a first protective layer configured to be wound around the inner layer. and a second protective layer made of a trix resin. a step of removing a part of the second protective layer to expose the winding end of the resin-impregnated fiber bundle; A process of peeling off the wound end portion, and pulling the peeled wound end portion to remove the resin-containing material. The method includes drawing out a dipped fiber bundle.

[0017] According to this embodiment, a resin-impregnated fiber bundle containing a reinforcing fiber bundle and a first matrix resin is a first protective layer configured to be wrapped around the liner; and and a second protective layer made of a matrix resin. It is possible to provide a method for recycling the reinforcing fibers.

[0018] The recycling method of this embodiment will be described in detail below.

[0019] FIG. 1 shows an example of a flowchart for explaining the recycling method according to this embodiment. As shown in FIG. 1, this embodiment includes a tank preparation step, a second protective layer partial removal step, The method includes at least a peeling step and a drawing step. Each step will be described in detail below.

[0020] (Tank preparation process) The recycling method according to this embodiment is a method for recycling a liner and a material disposed on the outer peripheral surface of the liner. The reinforcing fiber bundles and the resin-impregnated fiber bundles containing the first matrix resin are wound around the liner. a first protective layer configured as above, and a second protective layer configured from the first matrix resin on the first protective layer; and a second protective layer formed on the tank.

[0021] The tanks to be prepared are, for example, tanks that are used for various purposes after production and then collected. or defective products at the manufacturing stage.

[0022] The reinforcing fibers used for the reinforcing fiber bundles of the resin-impregnated fiber bundles (fiber-reinforced resin layer) are, in particular, Examples include, but are not limited to, glass fiber, carbon fiber, metal fiber, alumina fiber, etc. Inorganic fibers such as aramid fibers, synthetic organic fibers such as aramid fibers, and natural organic fibers such as cotton are used. These fibers may be used singly or in combination (as mixed fibers). .

[0023] The first matrix resin used in the resin-impregnated fiber bundle is not particularly limited. However, for example, phenolic resin, urea resin, unsaturated polyester resin, vinyl ester resin, resin, polyimide resin, bismaleimide resin, polyurethane resin, diallyl phthalate resin, epoxy resin, or a mixture thereof.

[0024] The first matrix resin may be, for example, a thermosetting resin or a thermoplastic resin. The first matrix resin is preferably a thermosetting resin. Examples of resins include epoxy resins, epoxy-modified polyurethane resins, and polyester resins. , phenol resin, polyurethane resin, or thermosetting polyimide resin. The epoxy resin is not limited to, but for example, bisphenol A epoxy epoxy resin, bisphenol AD type epoxy resin, bisphenol F type epoxy resin, phenol Cresol novolac epoxy resin, cresol novolac epoxy resin, glycidyl ester Epoxy resins include linear and branched types. The first matrix resin may be used alone or in combination of two or more. They may also be used in combination.

[0025] The resin-impregnated fiber bundles used to form a layer (fiber-reinforced resin layer) made of resin-impregnated fiber bundles are The resin-impregnated fibers can be prepared by methods conventionally known in the art. The bundle is not particularly limited, but for example, a process in which a reinforcing fiber bundle is impregnated with a liquid resin is used. It can be prepared by repreg molding.

[0026] The resin-impregnated fiber bundle can be wound by a conventionally known method. For example, the resin-impregnated fiber bundle is wound using a conventionally known filament winding method. The filament winding device is a device that applies resin impregnation to the outer periphery of the mold. The fiber bundle can be repeatedly wound around the mold, forming a fiber layer of resin-impregnated fiber bundles around the outer periphery of the mold. When a thermosetting resin (for example, an epoxy resin) is used as the resin, A fiber layer impregnated with epoxy resin is formed on the outer periphery of the mold. The resin is hardened by heat or the like. The number of windings is not limited, but the resin-impregnated fiber bundle is wound around the outside of the mold. The fiber layer formed around the circumference is wound until it reaches a thickness of usually 10mm to 30mm. After that, the resin-impregnated fibers are cured by appropriate heat treatment to obtain a fiber-reinforced resin layer. The heat treatment can be carried out using, for example, a heat curing oven.

[0027] An embodiment according to the present invention will be described in detail below.

[0028] An example of the configuration of the tank in this embodiment will be described below with reference to FIG. The following configuration example shows one embodiment, and the present embodiment will be described by the following configuration example. It is not intended to be limiting.

[0029] FIG. 2 is a cross-sectional view showing an example of the configuration of the tank 100 that can be used in this embodiment. 1 shows a cross-sectional view taken along a plane parallel to and passing through the central axis of the tank 100. The central axis (dotted line X) of the tank 100 passes through the center of the circle of the tank body having a substantially cylindrical shape. The tank 100 can be used to store gases such as compressed hydrogen. For example, the tank 100 can be filled with compressed hydrogen and used to supply hydrogen to a fuel cell. It will be installed in fuel cell vehicles to supply electricity.

[0030] 2 is a schematic cross-sectional view of the tank 100 according to this embodiment taken along the axial direction. 100 is a hollow container centered on a central axis X, and contains high-pressure hydrogen gas, high-pressure natural gas, etc. As shown in FIG. 2, the tank 100 is a pressure vessel for storing a high-pressure fluid. A resin liner 10 to be housed, a reinforcing layer 20 covering the outer peripheral surface of the liner 10, and a protective layer 30 covering the outer peripheral surface of the reinforcing layer 20. The valve-side cap 40 and the end-side cap 60 are provided at both ends of the tube 100. A valve 50 is attached to the valve-side base 40 .

[0031] The liner 10 has a body and two side edges, and defines an interior space for storing gas. It has gas barrier properties that seal the internal space to prevent gases such as hydrogen from leaking to the outside. The body portion extends a predetermined length along the central axis X of the tank 100 shown in FIG. The side end is a dome-shaped part that is formed continuously on both sides of the body. The diameter of each side end decreases as it moves away from the body, and the center of the narrowest part Each opening is provided with a valve-side cap 40 and an end-side cap 60. It is being done.

[0032] The liner 10 is made of a resin having gas barrier properties. Examples of such resins include: Examples of the resin include polyethylene resin, polypropylene resin, and nylon resin. As the resin, one type may be used alone, or two or more types may be used in combination. The liner 10 is formed by mixing a gas impermeable material such as a hydrogen storage alloy into the resin. It may be made.

[0033] The reinforcing layer 20 is made of carbon fiber bundles and resin-impregnated carbon fiber bundles containing a second matrix resin (carbon The reinforcing layer 20 is made of carbon fiber reinforced plastic (CFRP). The resin-impregnated carbon fiber bundle containing the matrix resin is wound around the liner. The reinforcing layer 20 is formed by, for example, hoop-winding and / or helically winding fibers of resin-impregnated carbon fiber bundles. The layer made of resin-impregnated carbon fiber bundles (carbon The fiber reinforced resin layer 20 mainly functions to reinforce the liner 10 (reinforcing layer). The second matrix resin impregnated into the fiber bundle may be, for example, a thermosetting resin or a thermoplastic resin. Carbon fibers can be produced by methods conventionally known in the art. The carbon fiber can be prepared by the following method. For example, carbon fiber made from acrylic, carbon fiber made from pitch, or polyvinyl Examples include carbon fibers made from alcohol. Among them, polyacrylonitrile fibers are PAN-based carbon fibers produced as raw materials are preferred.

[0034] The protective layer 30 is composed of a first protective layer 30a and a second protective layer 30b. The protective layer 30a is made of a resin-impregnated glass fiber bundle (glass fiber Glass fiber reinforced plastic (GFRP)) and a resin containing glass fiber bundles and a first matrix resin. The oil-impregnated fiber bundle is wound around the liner. Specifically, the first protective layer 3 0a is a glass fiber bundle impregnated with resin, for example, by helical winding and / or hoop winding. The first matrix impregnated in the glass fiber bundle is wound around the outer peripheral surface of the reinforcing layer 20. The thermoplastic resin may be, for example, a thermosetting resin or a thermoplastic resin.

[0035] The protective layer 30 includes a first protective layer 30a that covers the outer peripheral surface of the reinforcing layer 20, and a second protective layer 3 The second protective layer 30b covers the outer peripheral surface of the winding 10a. In the heat curing step after the completion of the wrapping, the wound film is heated to form the first protective layer 30a. A part of the first matrix resin impregnated in the glass fiber bundles is adhered to the surface of the glass fiber reinforced resin. It may be a layer formed by hardening in an exuded state.

[0036] The first protective layer 30a is a resin-impregnated layer made of glass fiber and a first matrix resin. The first matrix resin contained in the first protective layer 30a is, for example, For example, it may be made of the same material as the second matrix resin of the reinforcing layer 20. The first matrix resin contained in the protective layer 30a is the same as the second matrix resin contained in the reinforcing layer 20. It may be made of the same material as the RIC resin or a different material.

[0037] The second protective layer 30b contains the first matrix resin as its main material. As described above, the first matrix resin is impregnated into the glass fiber bundles of the first protective layer 30a. A part of the first matrix resin bleeds out onto the surface of the first protective layer 30a. The content of the first matrix resin in the second protective layer 30b is equal to that of the first matrix resin in the first protective layer 30a. The content of the second protective layer 30b is higher than that of the first matrix resin. The first protective layer 30a may be made of a tungsten carbide resin alone or may contain a portion of the glass fiber separated from the first protective layer 30a. That's fine too.

[0038] In FIG. 2, the valve-side mouthpiece 40 is substantially cylindrical, and is made of the liner 10 and the reinforcing layer 20. The valve-side nozzle 40 is fitted between the tank 100 and fixed thereto. In this embodiment, the valve-side mouthpiece 40 is made of, for example, stainless steel. However, it may be made of other metals such as aluminum, or may be made of resin. The valve 50 has a cylindrical portion formed with a male screw, and the valve side base The valve 50 is threaded into the female thread formed on the inner surface of the valve 40. The opening of the lube-side nozzle 40 is closed. The end-side nozzle 60 is made of, for example, aluminum. It is assembled with a part exposed to the outside, and it works to guide the heat inside the tank to the outside. do.

[0039] The second matrix resin is independent of the first matrix resin, but may be, for example, The second matrix resin may be made of the same material as the first matrix resin. For example, a thermosetting resin or a thermoplastic resin can be used. As described above, the resin and the second matrix resin may be made of the same material, but may be made of different materials. The second matrix resin may be a thermosetting resin. As the thermosetting resin, for example, those described above for the first matrix resin are preferred. The second matrix resin may also be used alone or in combination of two or more. The above may be used in combination.

[0040] The layer made of resin-impregnated fiber bundles (fiber-reinforced resin layer) is, for example, a filament winding The filament winding molding can be formed by a reinforcing fiber bundle. If necessary, multiple strands can be aligned and impregnated with matrix resin to fit the rotating substrate or mold. It can be manufactured by winding it at an appropriate angle while applying tension to the desired thickness. can.

[0041] (Step of Partially Removing Second Protective Layer) The recycling method according to this embodiment involves removing a portion of the second protective layer and recycling the resin-impregnated fiber bundle. This includes exposing the end of the winding.

[0042] FIG. 3 shows the tank 100 shown in FIG. 2 with the second protective layer 30b partially removed. 4 is a schematic diagram showing a state in which the first protective layer 30a is exposed. 1 is an enlarged schematic diagram of the area surrounded by the dotted line in FIG. 1, showing the exposed end of the resin-impregnated fiber bundle. The winding end of the resin-impregnated fiber bundle is a layer made of the resin-impregnated fiber bundle. The adhesive is then cured or solidified in the state where it is attached to the surface of the (fiber-reinforced resin layer) and fixed in place. The end of the resin-impregnated fiber bundle is not bent but hardened or solidified and fixed. 5 is a schematic diagram showing the shape of the winding end portion of the resin-impregnated fiber bundle. Only the end edge is shown, and the underlying layers, specifically the resin-impregnated fiber bundles, are omitted. In addition, since the tank usually has a curved surface, the end of the winding of the resin-impregnated fiber bundle is The table showing the position of the end of the winding on the tank surface is By providing a display on the tank surface, the second protection The areas where the layer is to be partially removed can be easily seen.

[0043] The method for removing a part of the second protective layer is not particularly limited. If there is a method that can expose the end of the resin-impregnated fiber bundle by removing a part of it, The method for removing a portion of the second protective layer may be, for example, a laser treatment, a dissolving treatment, or a heat treatment. or a combination thereof.

[0044] As described above, laser processing can be used as a method for removing a portion of the second protective layer. The laser used for laser processing is, for example, a carbon dioxide laser (CO2 laser). , YAG laser, fiber laser, semiconductor laser, etc. It is preferable to use a carbon dioxide gas laser. The carbon dioxide gas laser is a type of gas laser. Using gaseous carbon dioxide (carbon dioxide) as a medium, continuous waves and high-power pulse waves in the infrared range are obtained. It is a laser that emits light in the 10.6 μm wavelength band, which is commonly used in carbon dioxide lasers. The laser light emitted by the laser is easily absorbed by resin, especially epoxy resin, so the second protective layer is efficiently On the other hand, carbon dioxide lasers can efficiently remove resin. However, it also tends to easily damage reinforcing fibers such as glass fiber or carbon fiber. It is preferable that the carbon dioxide gas laser has a low output. For example, the average output of a continuous wave carbon dioxide gas laser is The average output is preferably 100W or less, more preferably 50W or less, and even more preferably 40 It is preferable that the power consumption is 1 W or less, and more preferably 30 W or less.

[0045] Figure 6 shows the first laser beam produced by a low-power (average power: 30 W) carbon dioxide laser (10.6 μm, continuous wave). This is an image showing the state after removing the epoxy resin as the second protective layer. By using a laser, the resin layer can be efficiently removed without damaging the glass fibers in the first protective layer. It is confirmed that the second protective layer can be removed. The first matrix resin in the protective layer may also be partially removed.

[0046] Figure 7 shows the first laser beam produced by a low-power (average power: 30 W) carbon dioxide laser (10.6 μm, continuous wave). The number of laser irradiations and etching when removing the epoxy resin as the second protective layer This is a graph showing the relationship between the depth (mm) and the laser irradiation time. A continuous wave carbon dioxide laser having the same wavelength is scanned at a constant speed so that the entire target area is irradiated. In one laser irradiation, the same area is irradiated as many times as possible. The laser is scanned so that the etching depth is not The depth indicated by the solid line represents the distance from the surface of the protective layer to the surface of the glass fiber bundles of the first protective layer. represents the distance from the surface of the second protective layer to the surface of the resin in the first protective layer. As shown, the etching depth to the resin surface in the first protective layer increases with the number of irradiations. On the other hand, the etching depth to the surface of the glass fiber bundle is about 15 times. This is because the laser power is constant from the low power carbon dioxide laser. This indicates that the resin layer can be efficiently removed without damaging the glass fibers in the first protective layer. do.

[0047] FIG. 8 shows the results of the experiment shown in FIG. 7 at the 10th, 20th, and 50th irradiations. This is an image showing the surface of the tank. From this image, it can be seen that the resin is etched more as the number of irradiations increases. The glass fibers were not damaged even after 20 and 50 irradiations. It is confirmed that

[0048] As described above, a dissolution process can be used to remove a portion of the second protective layer. Specifically, a part of the second protective layer can be formed by bringing the dissolving solution into contact with the part of the second protective layer. It can be removed by

[0049] The dissolution of the first matrix resin constituting the second protective layer is carried out using a solvent capable of dissolving the resin. The dissolving liquid is preferably any liquid capable of dissolving the first matrix resin. Examples of the solvent include, but are not limited to, acidic solutions, organic solvents, hydrogen peroxide solutions, and ions. The liquid contains at least one liquid selected from the group consisting of: This allows the resin to swell and be removed efficiently. The dissolving solution may be used alone or in combination of two or more.

[0050] Examples of the acidic solution include phosphoric acid and sulfuric acid. A solution containing sulfuric acid (for example, 90% by mass or more) as described in Japanese Patent Application Publication No. 20020-37638 (above concentration), a solution containing phosphoric acid as described in JP 2020-50704 A, etc. The acidic component may be used alone or in combination of two or more. For example, the resin-impregnated fiber bundle may be immersed in concentrated sulfuric acid to dissolve and remove the resin. The temperature of the concentrated sulfuric acid can be, for example, 100 to 300°C. Therefore, no substantial decrease in strength is observed in the carbon fiber after the resin is removed.

[0051] Examples of the organic solvent include aliphatic hydrocarbon solvents, aromatic hydrocarbon solvents, and alcohols. Examples of the solvent include alcohol-based solvents, ketone-based solvents, ether-based solvents, amide-based solvents, and ester-based solvents. The organic solvent may be used alone or in combination of two or more. Examples of the aliphatic hydrocarbon solvent include pentane, hexane, heptane, and octane. Examples of aromatic hydrocarbon solvents include benzene, toluene, Examples of organic solvents containing two or more components include petroleum benzene, xylene, etc. The organic solvent may contain a decomposition catalyst. Examples of catalysts include alkali catalysts such as those described in JP 2020-45407 A. Metal compounds are included.

[0052] Examples of ionic liquids include imidazolium-based and pyridinium-based cations, A small amount selected from pyrrolidinium-based, quaternary ammonium-based, and quaternary phosphonium-based compounds Ionic liquids containing at least one cation are also suitable. They may be used alone or in combination of two or more.

[0053] The method for bringing the dissolving solution into contact with a part of the second protective layer is not particularly limited. However, for example, a sponge member or the like soaked in a dissolving solution is placed in contact with the target area of the second protective layer. One method is to place the

[0054] In this embodiment, the method for removing a portion of the second protective layer includes laser processing and dissolution. A combination of treatments may also be used, for example, first by laser treatment to roughly remove the resin; The remaining resin can then be removed with a dissolving solution.

[0055] As described above, heat treatment can be used as a method for removing a portion of the second protective layer. Specifically, the second protective layer can be removed by selectively heating a portion of the second protective layer. The temperature of the heat treatment is, for example, 550°C to 700°C from the viewpoint of thermal decomposition of the resin. It can be the following:

[0056] The means for partially heating the second protective layer is not particularly limited, but may be, for example, For example, a heater can be used.

[0057] In this embodiment, as shown in FIG. 9, the winding end of the resin-impregnated fiber bundle is bent. The tank may be fixed by hardening or solidification in the lifted state. The resin-impregnated fiber bundle is fixed in a bent state at the end of the winding of the resin-impregnated fiber bundle. In this embodiment, the bending portion is a portion where the resin is impregnated. This refers to the end of a fiber bundle that is formed by bending it. Generally, it refers to the end of a resin-impregnated fiber bundle. The part is not bent but is attached to the underlying resin-impregnated fiber bundle as shown in Figures 4 and 5. The end of the resin-impregnated fiber bundle is fixed in place by hardening or solidifying. The difference between the end of the winding and the resin-impregnated fiber bundle located below it is determined by using a tool such as a scraper. The end of the reinforcing fiber is attached to the end of the winding. Because of the exposed or adjacent structure, it is not possible to insert an instrument completely between them. As shown in 0, only the top part of the reinforcing fiber bundle may peel off, leaving the bottom part intact. (Up-down splitting). In addition, the reinforcing fiber bundles not only split upward and downward, but also split in the direction shown in Figure 11. As shown in the figure, the reinforcing fiber bundles may split to the left and right (left-right splitting). If the resin-impregnated fiber bundle is pulled out in this state, the reinforced fiber bundle will come off the tank surface with the cracks remaining in the bundle. The reinforced fibers may peel off from the bobbin, making it difficult to accurately collect them, or the reinforced fibers may break. This can cause problems such as a crack or a decrease in workability. As shown in the figure, the end of the resin-impregnated fiber bundle is cured or solidified in a bent state. It is preferable that the end of the winding is hardened or solidified in a folded state. When the material is fixed in place, it is difficult to insert a tool such as a scraper between the folded part and the layer below. It can be inserted properly, preventing the occurrence of cracks and allowing the end of the winding to be easily peeled off. That is, the bent portion formed by bending and fixing the resin-impregnated fiber bundle can be When inserting a tool such as a scraper, the bent part and the resin-containing material underneath it may be damaged. It acts as a guide between the immersed fiber bundles, preventing the occurrence of tears and preventing bending points. The resin-impregnated fiber bundles can be easily peeled off from the reinforcing layer (intermediate layer) 20. The end of the resin-impregnated carbon fiber bundle is also hardened or solidified in a bent state. This allows the resin-impregnated fiber bundles that constitute the reinforcing layer (intermediate layer) to be drawn out. When peeling, the end of the winding can be easily peeled off.

[0058] The folded state is the part of the tree behind the folded part (the part at the tip of the end of the winding). The oil-impregnated fiber bundle is wound in the area before the bend (the area wound first, the tip of the end of the winding). The resin-impregnated fiber bundle may be folded over the other end of the fiber bundle (the part opposite to the folded side). The resin-impregnated fiber bundles behind the bend are The part of the resin-containing material behind the bent part may be bent downward. The resin-impregnated fiber bundle is folded so that it is on top of the resin-impregnated fiber bundle in front of the bending point. 13 is a schematic diagram showing the fixed state of the resin-impregnated fiber after the bending point. The bundle is bent and fixed so that it is under the resin-impregnated fiber bundle in front of the bend. FIG. 1 is a schematic diagram showing the configuration of the device.

[0059] The form in which the resin-impregnated fiber bundle is fixed in a folded state is not particularly limited. However, for example, when the resin impregnated in the reinforcing fiber bundle is hardened or The fixing may be achieved by, for example, bending the end of the winding. For example, the end of the winding can be hardened by heat treatment in this state. Alternatively, the film may be folded over and then hardened by blowing hot air onto the end of the film.

[0060] As mentioned above, when recycling reinforcing fibers from resin-impregnated fiber bundles, the ends of the fibers are wound on the winding roller. To fix the part, first, cut the end of the resin-impregnated fiber bundle with a tool such as a scraper. The resin-impregnated fiber bundle is peeled off from the tank surface using a By fixing the resin-impregnated fiber bundle in a bent state at the end, A scraper or similar tool is inserted between the bent part at the end of the cable and the resin-impregnated fiber bundle located below it. This is made by bending and fixing the resin-impregnated fiber bundle. When inserting a scraper or other tool, the bent part may be caught at the end of the part to be peeled. It acts as a guide between the edge and the resin-impregnated fiber bundle underneath, This is because the resin-impregnated fiber bundle can be easily peeled off while preventing the occurrence of cracks.

[0061] It is preferable that the bending portion extends to both longitudinal sides of the resin-impregnated fiber bundle. That is, the end edges formed by bending the resin-impregnated fiber bundle are It is preferable that the length of the resin-impregnated fiber bundle reaches both longitudinal sides of the resin-impregnated fiber bundle. By folding it so that it reaches the edge, the end of the resin-impregnated fiber bundle can be When the portion is peeled off, tearing of the fiber bundles can be more effectively suppressed.

[0062] As shown in Figures 12 and 13, the bending direction is different from the winding direction. It is preferable that the fiber bundle is bent. In addition, the winding end of the resin-impregnated fiber bundle is In this specification, the "folded state" This means that both longitudinal sides of the resin-impregnated fiber bundle behind the bend are This means that the fiber bundle is folded so that it matches both longitudinal sides of the resin-impregnated fiber bundle at the front of the fiber bundle. This term indicates one aspect of the "foldable" form. The rear part of the resin-impregnated fiber bundle should be placed above the front part of the resin-impregnated fiber bundle from the bend point. FIG. 15 is a schematic diagram showing the folded and fixed state. The resin-impregnated fiber bundle is folded back so that it is underneath the resin-impregnated fiber bundle in front of the bending point. FIG. 1 is a schematic diagram showing the state in which the electrode is fixed.

[0063] 12 and 13 show that the resin-impregnated fiber bundle is folded so that the folding direction is different from the winding direction. 16 is a schematic diagram showing a bent state. Also, FIG. 16 explains the bending angle. 1 is a schematic diagram showing the bending portion viewed from the outside of the tank in the radial direction. In FIG. 16, the longitudinal direction (dotted arrow) of the resin-impregnated fiber bundle in front of the bending point and the longitudinal direction of the resin-impregnated fiber bundle after the bending point (solid arrow). The angle is indicated by θ. In this embodiment, if the folding direction is different from the winding direction, is the longitudinal direction of the resin-impregnated fiber bundle in the front part of the bending point and the The bending angle θ between the longitudinal direction of the resin-impregnated fiber bundle is more than 0° and less than 180°. In this embodiment, the longitudinal direction of the resin-impregnated fiber bundle in the portion before the bending portion and The bending angle θ between the longitudinal direction of the resin-impregnated fiber bundle after the bending point is 1° It is preferable that the angle is 5° or more, more preferable that the angle is 10° or more. Preferably, the angle is 15° or more, and more preferably 20° or more. The bending angle is preferably 150° or less, and more preferably 120° or less. It is preferable that the angle is 90° or less, and more preferably 80° or less. The upper and / or lower limits of the value ranges may be arbitrarily combined to define a preferred range. For example, the bending angle is 1° or more and 150° or less, and 10° or less. The angle is either above 120° or below 20° or above 90°.

[0064] The bending angle θ is the angle of the resin-impregnated fiber bundle in front of the bending point (the portion immediately before the bending point). The line passing through the center line of the short side (the line along the dotted arrow in Figure 16) and the axis of the tank (the line along the chain line in Figure 2) A plane perpendicular to line X) and the center line in the short direction of the resin-impregnated fiber bundle after the bend The angle between the tank and the plane passing through the tank (the line along the solid arrow in Figure 16) and perpendicular to the tank axis is defined as The preferable numerical ranges may be the ranges described above.

[0065] Regarding the bending length, the length of the resin-impregnated fiber bundle after the bending point is particularly restricted. Although not limited thereto, it is, for example, 10 mm to 300 mm.

[0066] (peeling process) Next, the recycling method according to this embodiment includes a step of peeling off the exposed end of the winding. include.

[0067] In the peeling step, as described above, a tool such as a scraper is used to peel the end of the winding and the The exposed end of the winding is peeled away from the tank surface by inserting it between the layers below. As described above, the resin-impregnated fiber bundle is bent at the winding end of the resin-impregnated fiber bundle. If the end is fixed in this state, the bent part at the end of the winding and the resin underneath it This makes it easier to insert a tool such as a scraper between the impregnated fiber bundles.

[0068] (Pulling process) The recycling method according to this embodiment involves pulling the peeled end of the winding, and The process includes drawing out the fiber bundles.

[0069] By applying tension to the peeled end of the winding and pulling it, the resin-impregnated fiber is removed from the tank. You can pull out the bundle.

[0070] The drawing process involves drawing out the resin-impregnated fiber bundle while subjecting it to heat treatment in a tank. The temperature of the heat treatment is preferably equal to or higher than the glass transition temperature of the first matrix resin and It is preferable that the temperature is lower than the thermal decomposition initiation temperature and lower than the thermal degradation temperature of the reinforcing fibers.

[0071] The heat treatment suppresses the thermal decomposition of the first matrix resin and the decrease in strength of the reinforcing fibers. In addition, the first matrix resin in the resin-impregnated fiber bundle can be softened. The tank is heated above the melt transition temperature, so the resin in the resin-impregnated fiber bundle softens. By carrying out the drawing process in the cured state, the resin-impregnated fiber bundle can be easily drawn out. Specifically, the resin-impregnated fiber bundle can be pulled out of the tank with less tension. Pulling out with a small tension can prevent breakage or damage to the reinforcing fibers. In addition, by heating the tank at a temperature below the temperature at which thermal decomposition begins, thermal decomposition of the resin is suppressed. By suppressing the thermal decomposition of the resin, excessive deformation and carbonization of the resin can be suppressed. As a result, even if a dissolution treatment is carried out in a later process, the resin in the resin-impregnated fiber bundle can be It can easily dissolve fats and oils. In addition, by suppressing the thermal decomposition of resins, Since it is possible to suppress the decrease in strength, the drawn resin-impregnated fiber bundle can be removed through the resin removal process. It can be used for other purposes without undergoing any processing, or after desired processing (cutting, etc.) Furthermore, by carrying out the heat treatment at a temperature lower than the thermal degradation temperature of the reinforcing fiber, the thermal degradation of the reinforcing fiber can be prevented. Deterioration can be suppressed, and a decrease in the strength of the reinforcing fibers can be suppressed.

[0072] In this embodiment, "pulling out the resin-impregnated fiber bundle" means "pulling out the resin-impregnated fiber bundle from the tank." This means that the fiber is drawn out continuously, and the concept of peeling off the resin-impregnated fiber bundle from the tank is also included. In one embodiment, the resin-impregnated fiber bundle is impregnated with the resin in the tank in a state where the resin is softened by heating. The resin-impregnated fiber bundle can be easily pulled out. When pulling out the resin-impregnated fiber bundle from the tank, a blade-shaped tool may be used to peel it off. A blade-shaped jig was used to cut the adhesive part (resin part) between the resin-impregnated fiber bundle and the tank surface. By contacting the resin portion between the two, it becomes easier to peel off the resin-impregnated fiber bundle. It is possible.

[0073] The method for drawing out the resin-impregnated fiber bundle is not particularly limited. For example, The end of the resin-impregnated fiber bundle is connected directly or indirectly to the roller, and the roller is rotated. It can be pulled out by rotating it.

[0074] The heat treatment can be carried out, for example, in a heat treatment chamber. Heat is applied in the bar to soften the matrix resin in the tank. It may be a furnace, and may have a space configured so that a heating medium can be introduced and / or discharged therein. The heating device may also have a

[0075] As a method for drawing out the resin-impregnated fiber bundle while subjecting it to heat treatment in a tank, for example, the method shown in Figure 1 As shown in Figure 7, the tank is placed in a heat treatment chamber and the resin is impregnated while being heated. A method of drawing a part of the fiber bundle out of the heat treatment chamber is also possible. For example, it can be transported to the outside through an outlet provided in a part of the heat treatment chamber. The soaked fiber bundle can be continuously transported, for example, by a transport roller.

[0076] In one embodiment using glass fibers as the reinforcing fibers, the temperature of the heat treatment is The temperature is equal to or higher than the glass transition temperature of the resin and lower than the thermal decomposition starting temperature, and the temperature of the glass fiber is In one embodiment using carbon fiber as the reinforcing fiber, The heat treatment temperature is equal to or higher than the glass transition temperature of the first matrix resin and lower than the thermal decomposition initiation temperature. and is lower than the thermal degradation temperature of the carbon fiber.

[0077] The thermal decomposition starting temperature of the resin can be measured using a thermogravimetric analyzer.

[0078] In one embodiment, the thermal decomposition initiation temperature is preferably 30°C to 55°C under a nitrogen atmosphere. The resin was heated to 0°C at a rate of 5°C / min. The weight change chart of the thermogravimetric analysis showed a 5% Preferably, the thermal decomposition starting temperature is 30°C or lower under a nitrogen atmosphere. The weight change chart of the thermogravimetric analysis obtained by heating the resin from 0°C to 550°C at 5°C / min. The temperature at which the thermal decomposition starts is 3% under a nitrogen atmosphere. Thermogravimetric analysis weight change chart obtained by heating the resin from 0°C to 550°C at a rate of 5°C / min. Generally, the above thermal decomposition starting temperature in a nitrogen atmosphere is The temperature is considered to be the temperature at which decomposition of the main chain and / or side chains of the resin begins.

[0079] In one embodiment, the thermal decomposition initiation temperature is preferably 30°C to 55°C under atmospheric conditions. The resin was heated to 0°C at a rate of 5°C / min. The weight change chart of the thermogravimetric analysis showed a 5% Preferably, the thermal decomposition starting temperature is 30°C or lower in the air. The weight change chart of the thermogravimetric analysis obtained by heating the resin from 0°C to 550°C at 5°C / min. The thermal decomposition starting temperature is preferably a temperature at which the weight loss of the polymer is 3% under atmospheric pressure. Thermogravimetric analysis weight change chart obtained by heating the resin from 0°C to 550°C at a rate of 5°C / min. This is the temperature at which a material shows a 1% weight loss. Since the oxygen contained in the material accelerates oxidative decomposition, assuming the same weight loss rate, the amount of oxygen in the material is about the same as that in the atmosphere. The thermal decomposition onset temperature measured in a nitrogen atmosphere is lower than that measured in a nitrogen atmosphere. become.

[0080] In one embodiment using glass fibers as the reinforcing fibers, the temperature is below the thermal degradation temperature of the glass fibers. By heating the tank with this, it is possible to prevent the strength of the glass fiber from decreasing. The thermal degradation temperature of the fiber is the temperature at which the tensile strength decreases by 1% when glass fiber is heated in the atmosphere. The minimum temperature at which the temperature at which the resin-impregnated fiber bundle is By measuring the tensile strength before and after the heat treatment, the decrease in strength can be calculated.

[0081] In one embodiment using carbon fibers as the reinforcing fibers, the temperature is set below the thermal degradation temperature of the carbon fibers. By heating the ink, it is possible to prevent the strength of the carbon fiber from decreasing. The degradation temperature is the temperature at which the tensile strength of carbon fiber decreases by 1% or more when the fiber is heated in the atmosphere. The minimum temperature at which the carbon fiber used in the resin-impregnated fiber bundle is heated can be defined as the minimum temperature at which the By measuring the tensile strength before and after, the loss in strength can be calculated.

[0082] In one embodiment, the temperature of the heat treatment is preferably 100° C. or higher, and preferably 120°C or higher, preferably 140°C or higher, preferably 160°C or higher, The temperature of the heat treatment is preferably 180° C. or higher, and more preferably 200° C. or higher. is preferably less than 400°C, preferably 390°C or less, preferably 380°C or less ° C. or less, preferably 370 ° C. or less, preferably 360 ° C. or less, The temperature is generally 350°C or less, preferably 340°C or less, and more preferably 330°C or less. Preferably, the temperature is 320°C or lower, more preferably 310°C or lower, and more preferably 300°C or lower. The heating temperature is 290°C or less, preferably 280°C or less. When the treatment temperature is 100°C or higher, the resin in the resin-impregnated fiber bundle can be effectively softened. If the heat treatment temperature is less than 400°C, the resin in the resin-impregnated fiber bundle may be thermally decomposed. It is also possible to easily suppress the deterioration of reinforcing fibers such as glass fibers and carbon fibers. The upper and / or lower limits of these numerical ranges may be combined in any desired manner. A range can be defined.

[0083] For example, the glass transition temperature of epoxy resin is about 100 to 200°C. The thermal decomposition temperature of epoxy resin is about 240 to 360°C. When heated, the resin undergoes excessive thermal decomposition, resulting in a significant decrease in the strength of the resin. This causes significant deformation and carbonization, making it difficult to dissolve and remove the resin with a solvent. The epoxy resin was heated from 30°C to 550°C at a rate of 5°C / min in a nitrogen atmosphere. The weight change chart of the thermogravimetric analysis obtained by the above procedure is shown in FIG. 18A. The temperature at which this occurs is approximately 350°C, and this temperature can be defined as the thermal decomposition starting temperature. FIG. 18B shows the results of the test for an example epoxy resin, which was tested at temperatures between 30°C and 550°C in an air atmosphere. The weight change chart of the thermogravimetric analysis obtained by heating the resin at 5°C / min up to 100°C is shown in Figure 18. In Figure 18A and Figure 18B, the inflection points are also shown. The temperature shown is 340°C, which can also be defined as the thermal decomposition starting temperature. As mentioned above, when heated in the atmosphere, oxidative decomposition occurs due to the oxygen contained in the air, and the weight When the reduction rate is the same, the thermal decomposition onset temperature measured in air is The temperature is lower than the measured thermal decomposition onset temperature. This occurs frequently, causing excessive decomposition of the main chain and / or side chain of the resin, and in some cases carbonization of the resin. When such thermal decomposition occurs, it becomes difficult to dissolve and remove the resin with a solvent. The strength of the resin-impregnated fiber bundle is reduced, making it impossible to reuse the resin-impregnated fiber bundle itself. In the range between the glass transition temperature and the thermal decomposition starting temperature specified in the state, thermal decomposition is suppressed. Since the resin can be softened while controlling the force, the resin-impregnated fiber bundle can be pulled out in that state. This makes it easy to obtain high-quality continuous resin-impregnated fiber bundles. This is a method for measuring the weight change when the weight is changed according to a predetermined program. For example, thermogravimetric analysis involves placing approximately 10 mg of sample in an aluminum, alumina, or platinum container. The test piece was placed and the weight change was measured when the temperature was increased at a constant heating rate (5°C / min). This can be done by:

[0084] From the viewpoint of more effectively suppressing the thermal decomposition of the resin, the temperature of the heat treatment is set to the temperature at which the thermal decomposition starts. It is preferable that the temperature is at least 1°C lower than the temperature at which thermal decomposition begins, and at least 5°C lower than the temperature at which thermal decomposition begins. It is preferable that the temperature is 10°C or more lower than the thermal decomposition starting temperature. It is preferable that the temperature is at least 15°C lower than the thermal decomposition starting temperature. It is preferable that the temperature is 20°C or more lower than the thermal decomposition starting temperature, and 25°C or more lower than the thermal decomposition starting temperature. It is preferable that the temperature is 30°C or more lower than the thermal decomposition starting temperature. It's nice.

[0085] FIG. 19 is a graph showing the thermal characteristics of carbon fiber as an example of reinforcing fiber, Carbon fiber was heated in air at temperatures (300℃, 400℃, 500℃) for a specified time (horizontal axis). The figure shows the strength ratio (tensile strength after heating / tensile strength before heating) at the time of heating. As can be seen, the strength of carbon fiber does not decrease even when heated to 400°C. When fiber is heated at 500°C, which is the temperature of conventional heat treatment, its strength decreases. This is thought to be due to the oxidation and deterioration of the carbon fiber caused by heat and oxygen. In addition, it is believed that the thermal decomposition temperature of resins is often lower than the thermal degradation temperature of carbon fibers.

[0086] FIG. 20 is a graph showing the tensile shear strength ratio of a resin (epoxy resin) at a predetermined temperature. Specifically, FIG. 20 shows the temperature at predetermined temperatures (23°C, 100°C, 150°C, 250°C, The tensile shear strength ratio (tensile shear strength when heated / tensile shear strength before heating) on the horizontal axis The vertical axis indicates the strength at 23°C, and the dotted line from 250°C to 350°C indicates the strength at 23°C. The tensile shear strength is measured by bonding two plates with resin as shown in Figure 21. The adhesive bond is formed by shear stress, which is a load that tends to displace the adherends in opposite directions. As shown in Figure 20, the strength of the resin increases as the heating temperature increases. It can be seen that the tensile shear strength decreases as the temperature increases. In this case, the resin-impregnated fiber bundle can be easily drawn out. For example, when the heating temperature is 150°C, When the tensile shear strength ratio is 0.2 or less, the tensile shear strength is greater during heating than before heating. The tensile shear strength of the resin-impregnated fiber bundle is 20% or less, so it can be pulled out with less force. In this embodiment, the temperature of the heat treatment is determined based on the tensile shear strength ratio. It is preferable that the temperature is such that the tensile shear strength ratio is 20% or less, and the temperature is such that the tensile shear strength ratio is 15% or less. It is preferable that the temperature is such that the tensile shear strength ratio is 10% or less. It is preferable that the temperature is such that the tensile shear strength ratio is 5% or less.

[0087] In this embodiment, the tank is not usually crushed or pulverized. Metal parts in the tank may be removed before the heating step, or may be removed after the heating step. It may be removed after the thermal process.

[0088] The heating method in one embodiment is not particularly limited. For example, heating in the atmosphere can be mentioned. Heat treatment in the atmosphere can be easily carried out. In particular, carbon dioxide is easily absorbed even in the presence of oxygen, such as in the atmosphere. This is effective because it can prevent the deterioration of fibers. By using superheated steam, the oxygen-containing atmosphere in the treatment atmosphere can be reduced. This can effectively prevent the decomposition and damage of the reinforcing fibers. For example, the heat treatment can be carried out by introducing atmospheric pressure superheated steam into an atmospheric pressure reaction vessel. The heat treatment is not particularly limited, but is preferably carried out in an inert atmosphere such as nitrogen. It is also possible to supply superheated steam and / or an inert gas (such as nitrogen) into the heat treatment chamber. The heat treatment may be carried out while the material is being fed.

[0089] In the recycling method according to this embodiment, the resin-impregnated fiber drawn out in the drawing step The bundles are held in a bundle shape by the reinforcing fibers and the matrix resin. Since the resin-impregnated fiber bundle is prevented from losing strength in the resin and reinforcing fibers, it can be used as is. Furthermore, the resin-impregnated fiber bundles obtained can be subjected to desired processing depending on the case. The material may be reused after being subjected to processing. Examples of processing include cutting the material to a desired size. For example, cut resin-impregnated fiber bundles are mixed with a binder resin or the like and solidified. By doing so, a sheet product can be produced.

[0090] (Removal process) The recycling method according to this embodiment involves removing the resin from the resin-impregnated fiber bundle to obtain reinforcing fibers. The method for removing the resin from the resin-impregnated fiber bundle is not particularly limited. However, preferably, dissolution and removal using a dissolving solution is used. Deterioration of reinforcing fibers (for example, glass fibers or carbon fibers) can be suppressed.

[0091] Hereinafter, a dissolving and removing process using a dissolving liquid will be described as an example of a process for removing resin. .

[0092] In the dissolving and removing step, the resin in the drawn resin-impregnated fiber bundle is dissolved and removed using a solvent. This is the process.

[0093] In one embodiment, the resin in the drawn resin-impregnated fiber bundle is removed by a dissolving and removing step. The resin can be dissolved and removed by contacting the resin-impregnated fiber bundle with a solvent. Dissolution removal avoids thermal stress and allows the reinforcement fibers (e.g., glass The deterioration of the carbon fiber (fiber or carbon fiber) can be suppressed. Specifically, the removal by the dissolving solution is as follows: Deterioration of the reinforcing fibers is less than that caused by pyrolysis. During the drawing process under certain heating conditions, excessive deformation and carbonization of the resin are suppressed, so the resin The resin in the oil-impregnated fiber bundle can be dissolved efficiently.

[0094] The resin is dissolved using a solvent capable of dissolving the resin in the resin-impregnated fiber bundle. The solvent is not particularly limited as long as it can dissolve the resin. At least one liquid selected from an acidic solution, an organic solvent, a hydrogen peroxide solution, and an ionic liquid These liquids can dissolve the resin or cause it to swell. The resin can be efficiently removed. One type of dissolving solution may be used alone. Two or more of these may be used in combination.

[0095] The resin is dissolved and removed by bringing a dissolving liquid into contact with the resin-impregnated fiber bundle. The method for contacting the resin-impregnated fiber bundle with the resin-impregnated fiber bundle is not particularly limited, but may be, for example, Dipping method, die coating method, bar coating method, roll coating method, or Among these, the dipping method is preferred. Specifically, the solution is placed in a bath and the resin-impregnated fiber bundle is immersed in the solution. In one embodiment, the reinforcing fibers can be contacted by conveying the reinforcing fibers through a roller. The pulled out resin-impregnated fiber bundle is conveyed by a conveying roller or the like, and the resin-impregnated fiber bundle is It can be immersed in the dissolution solution.

[0096] The degree of solubility of the resin in the dissolving and removal process varies depending on the type of dissolving solution, the processing temperature, the processing time, etc. The treatment time can be adjusted by, for example, the conveying speed of the resin-impregnated fiber bundle. The treatment time is not particularly limited, and can be adjusted depending on the type of solvent and resin. It can be set appropriately.

[0097] The temperature of the dissolving liquid (liquid temperature) can be set appropriately taking into consideration the degree of dissolving and removal. The temperature of the liquid (liquid temperature) is, for example, 20°C or higher, 40°C or higher, or 60°C or higher. , 80 ° C or more, and, for example, 300 ° C or less, 250 ° C or less, 200 °C or less, 150 °C or less, 100 °C or less.

[0098] The resin may be dissolved and removed by spraying a dissolving liquid onto the resin-impregnated fiber bundle. That is, by applying a spray pressure to the solution and bringing it into contact with the resin-impregnated fiber bundle, The resin in the resin-impregnated fiber bundle can be removed by using the dissolving liquid. The spraying device used is not particularly limited, and for example, a high-pressure washing device or the like can be used. .

[0099] The nozzle pressure when spraying the solution is preferably 1 MPa or more, and more preferably 5 MPa or more. Pa or more, preferably 8 MPa or more, and preferably 10 MPa or more. The pressure can efficiently remove the resin from the resin-impregnated fiber bundle. Preferably, it is 30 MPa or less, preferably 25 MPa or less, preferably 22 MPa or less. The pressure is preferably 20 MPa or less, and more preferably 20 MPa or less. The nozzle and the target when spraying the dissolving liquid can be effectively prevented from being damaged by the liquid. The distance between the resin-impregnated fiber bundles is preferably 10 to 200 cm, more preferably 30 to 400 cm. It is 100cm.

[0100] The resin may be dissolved and removed by a combination of immersion in a dissolving solution and spraying of the dissolving solution.

[0101] (Sizing agent application process) The recycling method according to the present embodiment uses reinforcing fibers (e.g., glass fibers) obtained by removing the resin. The method may include a step of applying a sizing agent to the fiber (fiber or carbon fiber).

[0102] After the removal process, the reinforcing fibers have had substantially all of the resin removed, and the bundles of reinforcing fibers have been loosened. By adding a sizing agent to this reinforcing fiber, The fiber bundle can be easily wound onto a bobbin, and the fuzziness of the reinforcing fibers and the tangles of the single fibers are prevented. The occurrence of clumps can be suppressed.

[0103] The sizing agent is not particularly limited, but examples thereof include epoxy resin, urea, and the like. Tan resin, vinyl ester resin, polyamide resin, nylon resin, polyolefin resin ( Polyethylene or polypropylene), polyester resin, phenolic resin, or a mixture of these Among these, epoxy resins, urethane resins, and vinyl ester resins are preferred. or polyolefin resin is preferred, and epoxy resin is more preferred. By using epoxy resin, it is possible to improve the adhesion between the reinforcing fiber and the epoxy resin. The sizing agent may be used alone or in combination of two or more. .

[0104] The application of the sizing agent to the reinforcing fibers is carried out by bringing the sizing agent into contact with the reinforcing fibers. The method for applying the sizing agent is not particularly limited, but may be, for example, Dipping method, die coating method, bar coating method, roll coating method, or Among these, the dipping method is preferred. Specifically, the sizing agent is placed in a sizing bath so that the material is immersed in the sizing agent. The reinforcing fibers can be applied by conveying the reinforcing fibers with rollers. The coating agent is dispersed or dissolved in water or an organic solvent such as acetone and used as a dispersion or solution. From the viewpoint of improving the dispersibility of the sizing agent and improving the liquid stability, A surfactant may be added to the dispersion or solution as appropriate.

[0105] (winding process) In the recycling method according to the present embodiment, the reinforcing fiber from which the resin has been removed obtained in the removing step is The step of winding the reinforcing fibers may be carried out after the removing step. When a sizing agent application step is included, the step is carried out after the sizing agent application step. preferable.

[0106] The winding can be performed using, for example, a winding roller. is equipped with a drive device that provides a driving force for winding the reinforcing fiber. Some guide rollers are also fitted with a drive unit that rotates the guide rollers. It is desirable that the winding tension, i.e., the tension applied to the reinforcing fibers, be as small as possible. By setting the winding tension within an appropriate range, it is possible to prevent breakage of the reinforcing fibers and winding slippage. As a result, longer continuous fibers can be obtained.

[0107] One embodiment of the present invention includes a step of drawing out a resin-impregnated fiber bundle while performing a heat treatment, and a step of drawing out the resin-impregnated fiber bundle. a step of removing the resin from the transported resin-impregnated fiber bundle; and and winding the fibers, and while the resin-impregnated fiber bundle is being drawn out upstream, the reinforcing fiber is being drawn downstream. That is, in one embodiment, the resin-impregnated fiber bundle is drawn under heating in the upstream. While the process of drawing out is being carried out, the process of winding the reinforced fiber is being carried out downstream, and the process of drawing out the reinforced fiber and the process of winding the reinforced fiber are being carried out upstream. During the winding process of the stream, a removal step and an optional sizing step are carried out. In one embodiment, while a step of drawing out the resin-impregnated fiber bundle under heating is performed upstream, The reinforcing fiber is wound downstream, and between the upstream drawing process and the downstream winding process, Then, a dissolving and removing step and optionally a sizing agent application step are carried out. After the drawing step under heating, the dissolving and removing step can be carried out immediately. Since the fiber bundle can be brought into contact with the dissolving liquid while it is still at a high temperature, the resin can be efficiently Specifically, a part of the resin-impregnated fiber bundle (preferably the end) can be removed from the tank. A part of the resin-impregnated fiber bundle is taken out, and the part is wound directly or indirectly on a winding machine. The resin-impregnated fiber bundle is then tensioned by a winding machine to form a continuous fiber. The fiber bundle is pulled out. The resin is removed from the pulled out resin-impregnated fiber bundle using a dissolving liquid. The resin is then removed and the resulting reinforcing fibers are wound up on a winding machine.

[0108] In the method for recycling reinforcing fibers according to the present embodiment, which has the above steps, Reinforcing fibers can be obtained efficiently.

[0109] According to the method for recycling reinforcing fibers of this embodiment described above, high-quality reinforcing fibers suitable for reuse can be produced. Reinforced fibers can be obtained efficiently. The obtained reinforcing fibers can be used in a wide range of applications. do.

[0110] The upper and / or lower limits of the ranges of values described in this specification can be arbitrarily combined. For example, the upper and lower limits of the numerical range can be arbitrarily set. The upper limits of the numerical ranges can be arbitrarily combined to define a preferred range. In addition, the lower limit values of the numerical ranges can be arbitrarily combined to define a preferred range. A preferred range can be defined in combination.

[0111] Throughout this specification, the terms "one embodiment," "one(a) embodiment," or "embodiment" may be used. Any reference to a particular feature, structure, or characteristic described with respect to that embodiment does not imply a is included in at least one embodiment. All references made throughout this specification and variations thereof do not necessarily refer to the same embodiment. isn't it.

[0112] Although the present embodiment has been described in detail above, the specific configuration is not limited to this embodiment. Even if there are design changes within the scope of the present disclosure, they are not included in the present disclosure. It is something that can be done. [Explanation of symbols]

[0113] 10 Liner 20 Reinforcement layer (middle layer) 30 protective layer 30a First protective layer 30b Second protective layer 40 Valve side nozzle 50 valves 60 End side cap 100 Tanks

Claims

1. 1. A method for recycling reinforcing fibers, comprising: a step of preparing a tank having at least a liner, a first protective layer disposed on an outer peripheral surface of the liner and configured so that a resin-impregnated fiber bundle containing a reinforcing fiber bundle and a first matrix resin is wound around the liner, and a second protective layer formed of the first matrix resin on the first protective layer; removing a portion of the second protective layer to expose the winding end of the resin-impregnated fiber bundle; peeling the exposed end of the winding; and The process of pulling the peeled end of the winding and pulling out the resin-impregnated fiber bundle. Including, The method, wherein a portion of the second protective layer is removed by contacting a dissolving solution with the portion of the second protective layer.

2. The method described in claim 1, wherein the step of drawing out the resin-impregnated fiber bundle is a step of drawing out the resin-impregnated fiber bundle while subjecting the tank to a heat treatment, and the temperature of the heat treatment is higher than the glass transition temperature of the first matrix resin and lower than the thermal decomposition onset temperature, and lower than the thermal degradation temperature of the reinforcing fiber.

3. The method according to claim 1, wherein the second protective layer is a layer formed by curing a part of the first matrix resin contained in the first protective layer in a state where the first matrix resin has oozed out.

4. The method of claim 1 , wherein the first matrix resin is an epoxy resin.

5. The method according to claim 1 , wherein the dissolution liquid comprises at least one liquid selected from an acidic solution, an organic solvent, a hydrogen peroxide solution, and an ionic liquid.

6. The method according to any one of claims 1 to 5, wherein the reinforcing fiber bundles are glass fiber bundles or carbon fiber bundles.

7. The method of claim 6, wherein the reinforcing fiber bundles are glass fiber bundles.

8. The method according to claim 7, further comprising a reinforcing layer between the protective layer and the liner, the reinforcing layer being configured such that resin-impregnated carbon fiber bundles containing carbon fiber bundles and a second matrix resin are wound around the liner.

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