Method for recycling of cans and reinforcing fibers

Abstract

The present embodiment provides a tank having a liner and a first protective layer, the first protective layer being provided on an outer peripheral surface of the liner, and being configured in a manner that a resin-impregnated fiber bundle containing a reinforcing fiber bundle and a first matrix resin is wound on the liner, and having a bent portion fixed in a state that the resin-impregnated fiber bundle is bent at an end portion of the winding of the resin-impregnated fiber bundle.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a tank and a method of recycling reinforcing fibers. BACKGROUND

[0002] Carbon fiber reinforced plastic (CFRP) is a material that is light in weight and high in rigidity, and can withstand high-pressure gas. Therefore, it is used as a reinforcing material in a hydrogen tank of a fuel cell (FC) vehicle or the like. In addition, a hybrid fiber reinforced plastic in which a glass fiber reinforced plastic (GFRP) layer is provided as a protective material on a carbon fiber reinforced resin layer is also adopted.

[0003] However, carbon fibers or glass fibers contained in carbon fiber reinforced resin or glass fiber reinforced resin are expensive, and in addition, the amount of CO2 generated at the time of manufacture is large and disposal is difficult, resulting in high environmental load. Therefore, a method of recycling carbon fibers or glass fibers from used fiber reinforced resin is being studied.

[0004] For example, Japanese Patent Application Publication No. 2017-104847 discloses a reinforcing fiber recycling method characterized by including the following stages: an unwinding stage in which reinforcing fibers are extracted while separating resin from a reinforcing member in which the reinforcing fibers are wound and the resin is impregnated; a sizing stage in which the extracted reinforcing fibers are passed through a sizing liquid to apply the sizing liquid to the reinforcing fibers; and a winding stage in which the reinforcing fibers to which the sizing liquid is applied are wound around a mandrel. SUMMARY

[0005] As disclosed in Japanese Patent Application Publication No. 2017-104847 or the like, a method of recycling reinforcing fibers from fiber reinforced resin (hereinafter also referred to as resin-impregnated fiber bundle) is studied. In the method of recycling reinforcing fibers, the winding end portion of the resin-impregnated fiber bundle is peeled from the surface of the tank using a doctor blade or the like, the peeled end portion is fixed to a winding roller, and extraction is performed by rotation drive of the roller.

[0006] However, when the winding end portion of the resin-impregnated fiber bundle is peeled from the surface, it is sometimes difficult to peel the resin-impregnated fiber bundle formed by containing the reinforcing fiber bundle well.

[0007] With regard to this problem, reference is made to Figures 1-3 for a detailed description. As shown in Figure 1 In the conventional tank, the winding end portion of the resin-impregnated fiber bundle is not bent, but is fixed by being hardened or cured in a state of being attached to the resin-impregnated fiber bundle located below. The winding end portion of the resin-impregnated fiber bundle is peeled by inserting an instrument such as a doctor blade between the winding end portion and the resin-impregnated fiber bundle located therebelow, but at this time, the structure in which the ends of the reinforcing fibers are exposed or approach the end of the winding end portion, so the instrument cannot be completely inserted therebetween, and the like.Figure 2 As shown, only the upper portion of the reinforcing fiber bundle is sometimes peeled off, and the lower side remains (tearing in the up-down direction). In addition, the reinforcing fiber bundle is not only torn on the upper side and the lower side, but sometimes also torn to the left and right (tearing in the left-right direction). Figure 3 As shown, the reinforcing fiber bundle is torn to the left and right (tearing in the left-right direction). If the resin-impregnated fiber bundle is pulled out in a state in which tearing has occurred, the reinforcing fiber bundle is peeled off from the surface of the can in a state in which the reinforcing fiber bundle is torn, and problems such as the inability to accurately recover the reinforcing fiber onto the bobbin, the occurrence of breakage of the reinforcing fiber, or a decrease in workability occur.

[0008] Therefore, an object of the present disclosure is to provide a can that can easily peel off the end portion of the winding of the resin-impregnated fiber bundle.

[0009] One aspect of the present embodiment is described below.

[0010] (1) A can having an inner liner and a first protective layer disposed on an outer peripheral surface of the inner liner, configured in such a manner that a resin-impregnated fiber bundle containing a reinforcing fiber bundle and a first matrix resin is wound on the inner liner,

[0011] At the end portion of the winding of the resin-impregnated fiber bundle, a bent portion in which the resin-impregnated fiber bundle is bent is fixed.

[0012] (2) The can according to (1), wherein the bent portion spans both lengthwise edges of the resin-impregnated fiber bundle.

[0013] (3) The can according to (1) or (2), wherein the resin-impregnated fiber bundle is bent in a direction different from the winding direction.

[0014] (4) The can according to (3), wherein, when the bent portion is viewed from the outside of the can in the radial direction, the bending angle between the lengthwise direction of the resin-impregnated fiber bundle at a portion in front of the bent portion and the lengthwise direction of the resin-impregnated fiber bundle at a portion behind the bent portion is greater than 1 degree and less than 180 degrees.

[0015] (5) The can according to (4), wherein the bending angle is 1 degree or more and 150 degrees or less, or 10 degrees or more and 120 degrees or less, or 20 degrees or more and 90 degrees or less.

[0016] (6) The can according to (1) or (2), wherein the resin-impregnated fiber bundle is bent in a direction identical to the winding direction.

[0017] (7) The can according to (6), wherein, when the bent portion is viewed from the outside of the can in the radial direction, the bending angle between the lengthwise direction of the resin-impregnated fiber bundle at a portion in front of the bent portion and the lengthwise direction of the resin-impregnated fiber bundle at a portion behind the bent portion is less than 1 degree.

[0018] (8) The tank according to any one of (1) to (7), wherein, at the bending portion, other material different from the resin-impregnated fiber bundle is arranged between the resin-impregnated fiber bundle of the portion in front of the bending portion and the resin-impregnated fiber bundle of the portion behind the bending portion.

[0019] (9) The tank according to (8), wherein the other material is in a shape of a ring or a plate.

[0020] (10) The tank according to any one of (1) to (9), wherein the reinforcing fiber bundle is a glass fiber bundle or a carbon fiber bundle.

[0021] (11) The tank according to (10), wherein the reinforcing fiber bundle is a glass fiber bundle.

[0022] (12) The tank according to (11), wherein the first protective layer is configured in a manner that a resin-impregnated glass fiber bundle including the glass fiber bundle and a first matrix resin is wound on the inner liner,

[0023] between the first protective layer and the inner liner, there is further provided a reinforcing layer configured in a manner that a resin-impregnated carbon fiber bundle including the carbon fiber bundle and a second matrix resin is wound on the inner liner.

[0024] (13) The tank according to (12), wherein, at an end portion of the winding of the resin-impregnated carbon fiber bundle, there is provided a bending portion fixed in a state that the resin-impregnated carbon fiber bundle is bent.

[0025] (14) The tank according to any one of (1) to (13), wherein, on the first protective layer, there is provided a second protective layer configured of the first matrix resin.

[0026] (15) A method for recycling a reinforcing fiber, comprising:

[0027] a step of preparing the tank according to any one of (1) to (14);

[0028] a step of peeling the bending portion of the end portion of the winding from the surface of the tank; and

[0029] a step of stretching the peeled end portion of the winding to extract the resin-impregnated fiber bundle.

[0030] According to the present disclosure, it is possible to provide a tank in which the end portion of the winding of the resin-impregnated fiber bundle can be easily peeled from the surface. BRIEF DESCRIPTION OF DRAWINGS

[0031] Hereinafter, features, advantages, techniques, and industrial significance of exemplary embodiments of the present invention will be described with reference to the accompanying drawings, in which like numerals refer to like elements throughout the drawings.

[0032] Figure 1is a schematic view showing a state in which the end portion of the winding is not bent and is fixed by hardening or curing.

[0033] Figure 2 is a schematic view for explaining a problem of a fiber bundle in the up-and-down direction that can occur when the end portion of the winding shown in Figure 1 is peeled off using a tool such as a spatula.

[0034] Figure 3 is a schematic view for explaining a problem of a fiber bundle in the left-and-right direction that can occur when the end portion of the winding shown in Figure 1 is peeled off using a tool such as a spatula.

[0035] Figure 4 is a schematic view showing a state in which the resin-impregnated fiber bundle in the portion behind the bent portion is located above the resin-impregnated fiber bundle in the portion in front of the bent portion.

[0036] Figure 5 is a schematic view showing a state in which the resin-impregnated fiber bundle in the portion behind the bent portion is located below the resin-impregnated fiber bundle in the portion in front of the bent portion.

[0037] Figure 6 is a schematic view showing a state in which the resin-impregnated fiber bundle in the portion behind the bent portion is located above the resin-impregnated fiber bundle in the portion in front of the bent portion.

[0038] Figure 7 is a schematic view showing a state in which the resin-impregnated fiber bundle in the portion behind the bent portion is located below the resin-impregnated fiber bundle in the portion in front of the bent portion.

[0039] Figure 8 is a schematic view for explaining a bending angle θ, and is a schematic view showing a state in which the bent portion is observed in the radial direction from the outside of the can.

[0040] Figure 9 is a schematic cross-sectional view showing a structure example of the can 100 as one aspect to which the present embodiment relates, and is a cross-sectional view of a face in the axial direction.

[0041] Figure 10 is a schematic view showing a state in which the portion of the second protective layer 30b as the surface layer of the can 100 shown in Figure 9 is removed, and the end portion of the winding of the first protective layer 30a is exposed.

[0042] Figure 11 is an example of a flowchart for explaining one aspect of the method to which the present embodiment relates.

[0043] Figure 12 This is a schematic diagram illustrating the extraction process under heating in this embodiment.

[0044] Figure 13A This is a graph representing an example of the thermal properties of epoxy resin, showing the weight change curve (TG curve) obtained by heating the resin under a nitrogen atmosphere (horizontal axis: temperature, vertical axis: weight loss rate).

[0045] Figure 13B This is a graph representing an example of the thermal properties of epoxy resin, showing a thermogravimetric analysis (TG curve) obtained by heating the resin in an atmospheric atmosphere (horizontal axis: temperature, vertical axis: weight loss rate).

[0046] Figure 14 This is a graph showing the thermal properties of carbon fiber as an example of a reinforcing fiber. It is a graph showing the strength ratio (tensile strength after heating / tensile strength before heating) of carbon fiber when heated in the atmosphere at a predetermined temperature (300°C, 400°C, 500°C) for a predetermined time (horizontal axis).

[0047] Figure 15 It is a graph showing the ratio of tensile shear strength of resin (epoxy resin) at a predetermined temperature.

[0048] Figure 16 It is used to explain the determination Figure 15 The diagram shows the structure of the test piece used in the tensile shear strength test.

[0049] Figure 17 This image shows the state after the epoxy resin, which serves as the second protective layer, has been removed using a low-output (average output: 30W) carbon dioxide laser (10.6μm, continuous wave).

[0050] Figure 18 This is a graph showing the relationship between the number of laser irradiations and the etching depth (mm) when removing epoxy resin, which serves as a second protective layer, using a low-output (average output: 30W) carbon dioxide laser (10.6μm, continuous wave).

[0051] Figure 19A It means in Figure 18 The image shown is of the surface of the tank after the 10th irradiation in the experiment.

[0052] Figure 19B It means in Figure 18 The image shown is of the surface of the tank after the 20th irradiation in the experiment.

[0053] Figure 19C It means inFigure 18 An image of the surface of the can at the 50th irradiation in the experiment shown.

[0054] Figure 20 is a schematic diagram showing a configuration in which a ring-shaped other material is interposed between the resin-impregnated fiber bundle of the portion in front of the bent portion and the resin-impregnated fiber bundle of the portion behind the bent portion.

[0055] Figure 21 is a schematic diagram showing a configuration in which a plate-shaped other material is interposed between the resin-impregnated fiber bundle of the portion in front of the bent portion and the resin-impregnated fiber bundle of the portion behind the bent portion.

[0056] Figure 22 is a schematic diagram showing a state in which the surface layer portion is removed to expose the winding end portion in a can in a configuration in which a ring-shaped other material is fixed at the bent portion.

[0057] Figure 23 is a schematic diagram showing a state in which the surface layer portion is removed to expose the winding end portion in a can in a configuration in which a plate-shaped other material is fixed at the bent portion. DETAILED DESCRIPTION

[0058] The present embodiment relates to a can having an inner liner and a first protective layer disposed on the outer peripheral surface of the inner liner, configured in such a manner that a resin-impregnated fiber bundle containing a reinforcing fiber bundle and a first matrix resin is wound on the inner liner, and having a bent portion in which the resin-impregnated fiber bundle is bent, fixed at the winding end portion of the resin-impregnated fiber bundle.

[0059] According to the present embodiment, it is possible to provide a can in which the winding end portion of the resin-impregnated fiber bundle can be easily peeled off. Specifically, the can according to the present embodiment has a bent portion in which the resin-impregnated fiber bundle is bent, fixed at the winding end portion of the resin-impregnated fiber bundle, and thus the winding end portion can be easily peeled off from the bent portion by inserting a tool such as a spatula between the bent portion and the layer therebelow.

[0060] The reinforcing fiber used for the reinforcing fiber bundle of the resin-impregnated fiber bundle (fiber-reinforced resin layer) is not particularly limited, and for example, glass fiber, carbon fiber, metal fiber, inorganic fiber such as alumina fiber, synthetic organic fiber such as aramid fiber, and natural organic fiber such as cotton can be used. These fibers can be used alone or in a mixture (as a mixed fiber).

[0061] The first matrix resin used for impregnating the fiber bundle with resin is not particularly limited, and examples thereof include phenol resin, urea resin, unsaturated polyester resin, vinyl ester resin, polyimide resin, bismaleimide resin, polyurethane resin, diallyl phthalate resin, epoxy resin, or a mixture thereof.

[0062] As the first matrix resin, for example, a thermosetting resin or a thermoplastic resin can be given. The first matrix resin is preferably a thermosetting resin. As the thermosetting resin, for example, an epoxy resin, an epoxy-modified polyurethane resin, a polyester resin, a phenol resin, a polyurethane resin, or a thermosetting polyimide resin, or the like can be given. As the epoxy resin, there is no particular limitation, and examples thereof include a bisphenol A-type epoxy resin, a bisphenol AD-type epoxy resin, a bisphenol F-type epoxy resin, a phenol novolak-type epoxy resin, a cresol novolak-type epoxy resin, a glycidyl ester-type epoxy resin, or the like. As the epoxy resin, it can be linear or branched. The first matrix resin can be used alone or in combination of two or more.

[0063] The resin-impregnated fiber bundle used for forming a layer (fiber-reinforced resin layer) composed of the resin-impregnated fiber bundle can be prepared by a method known in the technical field. The resin-impregnated fiber bundle is not particularly limited, and for example, it can be prepared by pre-impregnation in which a liquid resin is impregnated in a reinforcing fiber bundle.

[0064] The method of winding the resin-impregnated fiber bundle can be performed by a method known in the past. For example, in the winding of the resin-impregnated fiber bundle, a filament winding device known in the past can be used. The filament winding device can repeatedly wind the resin-impregnated fiber bundle around the outer periphery of a mold, and can form a fiber layer from the resin-impregnated fiber bundle around the outer periphery of the mold. In the case where a thermosetting resin (for example, an epoxy resin) is used as the resin, a fiber layer impregnated with the epoxy resin is formed around the outer periphery of the mold. Then, the resin is cured by heating or the like. The number of windings is not limited, and generally, the resin-impregnated fiber bundle is wound until the thickness of the fiber layer formed around the outer periphery of the mold becomes 10 mm to 30 mm. After the winding, the resin-impregnated fiber is cured by appropriately performing a heating treatment, and a fiber-reinforced resin layer can be obtained. The heating treatment can be performed using, for example, a heat curing oven.

[0065] The can according to the present embodiment has a bent portion at the end portion of the resin-impregnated fiber bundle where the winding of the resin-impregnated fiber bundle is completed, and the resin-impregnated fiber bundle is fixed in a state of being bent. In the present embodiment, the bent portion refers to the end portion generated by the bending of the resin-impregnated fiber bundle.

[0066] In conventional containers, the winding ends of resin-impregnated fiber bundles are not bent as in this embodiment, but are instead hardened or cured and fixed in a state of being attached to the surface of the layer composed of resin-impregnated fiber bundles (fiber-reinforced resin layer). Figure 1 ).exist Figure 1 In this embodiment, only the winding end of the resin-impregnated fiber bundle is shown, omitting the underlying layer, specifically the resin-impregnated fiber bundle. Furthermore, the can typically has a curved surface, so the winding end of the resin-impregnated fiber bundle is fixed along this curved surface. On the other hand, in the can according to this embodiment, the winding end of the resin-impregnated fiber bundle is hardened or cured and fixed in a bent state. This bent state can be such that the resin-impregnated fiber bundle in the portion further back from the bent portion (the portion on the front end side of the winding end) is above the resin-impregnated fiber bundle in the portion forward from the bent portion (the portion that was wound first, the portion opposite to the front end side of the winding end), or it can be such that the resin-impregnated fiber bundle in the portion further back from the bent portion is below the resin-impregnated fiber bundle in the portion forward from the bent portion. Figure 4 This is a schematic diagram showing a shape in which a resin-impregnated fiber bundle located behind the bending portion is positioned above a resin-impregnated fiber bundle located in front of the bending portion, and is thus bent and fixed. Figure 5 This is a schematic diagram showing a shape in which a resin-impregnated fiber bundle located behind the bending portion is positioned below a resin-impregnated fiber bundle located in front of the bending portion, and is thus bent and fixed.

[0067] There are no particular limitations on the method of fixing the resin-impregnated fiber bundle in a bent state. For example, a method in which the resin impregnated in the reinforcing fiber bundle hardens or cures while it is bent can be used for fixing. Fixing can be performed, for example, by heat treatment to cure it while the winding end is bent. Alternatively, it can be cured by blowing hot air near the winding end while the winding end is bent.

[0068] As described above, when recycling reinforcing fibers from resin-impregnated fiber bundles, in order to fix the ends to the take-up roller, the winding end of the resin-impregnated fiber bundle is first peeled off from the can surface using a scraper or similar tool. At this time, as shown in this embodiment, by fixing the winding end of the resin-impregnated fiber bundle in a bent state, a scraper or similar tool can be easily inserted between the bent portion of the winding end and the resin-impregnated fiber bundle located below it. This is because the bent portion formed by fixing the resin-impregnated fiber bundle in a bent state acts as a guide between the winding end of the portion to be peeled and the resin-impregnated fiber bundle located below it when the scraper or similar tool is inserted, suppressing tearing and easily peeling the resin-impregnated fiber bundle from the bent portion.

[0069] In the present embodiment, the bending site preferably straddles both lengthwise edges of the resin-impregnated fiber bundle. That is, the end edge formed by bending the resin-impregnated fiber bundle reaches both lengthwise edges of the resin-impregnated fiber bundle. By bending in a manner straddling both lengthwise edges of the resin-impregnated fiber bundle, it is possible to more effectively suppress tearing of the fiber bundle when peeling the winding end portion of the resin-impregnated fiber bundle from the bending site.

[0070] In the present embodiment, as shown in Figure 4 and Figure 5 , the resin-impregnated fiber bundle is preferably bent in a manner in which the bending direction differs from the winding direction. In the present embodiment, the winding end portion of the resin-impregnated fiber bundle can be fixed in a folded-back state. In the present specification, the "folded-back state" refers to a state in which both lengthwise edges of the resin-impregnated fiber bundle in a portion posterior to the bending site are bent in unison with both lengthwise edges of the resin-impregnated fiber bundle in a portion anterior to the bending site, and is a term indicating one manner of "bending" configuration. Figure 6 is a schematic diagram indicating a configuration in which the resin-impregnated fiber bundle in a portion posterior to the bending site is folded back and fixed in a manner in which it is positioned above the resin-impregnated fiber bundle in a portion anterior to the bending site. Figure 7 is a schematic diagram indicating a configuration in which the resin-impregnated fiber bundle in a portion posterior to the bending site is folded back and fixed in a manner in which it is positioned below the resin-impregnated fiber bundle in a portion anterior to the bending site.

[0071] Figure 4 and Figure 5 is a schematic diagram indicating a configuration in which the resin-impregnated fiber bundle is bent in a manner in which the bending direction differs from the winding direction. In addition, Figure 8 is a schematic diagram for explaining the bending angle, and is a schematic diagram when the bending site is observed from the outside of the can in the radial direction. In Figure 8In the present embodiment, the bending direction is different from the winding direction, and preferably indicates that the bending angle θ between the length direction of the resin-impregnated fiber bundle of the front portion with respect to the bending portion and the length direction of the resin-impregnated fiber bundle of the rear portion with respect to the bending portion is preferably greater than 1 degree and less than 180 degrees. In the present embodiment, the bending angle θ between the length direction of the resin-impregnated fiber bundle of the front portion with respect to the bending portion and the length direction of the resin-impregnated fiber bundle of the rear portion with respect to the bending portion is preferably 1 degree or greater, preferably 5 degrees or greater, preferably 10 degrees or greater, preferably 15 degrees or greater, and preferably 20 degrees or greater. In addition, the above-described bending angle is preferably 150 degrees or less, preferably 120 degrees or less, preferably 90 degrees or less, and preferably 80 degrees or less. The upper limit value and / or the lower limit value of these numerical ranges can be arbitrarily combined to define a preferable range. For example, the above-described bending angle is 1 degree or greater and 150 degrees or less, 10 degrees or greater and 120 degrees or less, or 20 degrees or greater and 90 degrees or less.

[0072] Figure 6 and Figure 7 is a schematic view showing a state in which the resin-impregnated fiber bundle is bent in a manner that the bending direction is the same as the winding direction. In the present embodiment, the bending direction is the same as the winding direction, and preferably indicates that the bending angle θ between the length direction of the resin-impregnated fiber bundle of the front portion with respect to the bending portion and the length direction of the resin-impregnated fiber bundle of the rear portion with respect to the bending portion is less than 1 degree.

[0073] In addition, the above-described bending angle θ can be defined as an angle between a plane that passes through the center line (a line along the dotted arrow of Figure 8 of the resin-impregnated fiber bundle of the front portion (the portion immediately in front) of the bending portion and is perpendicular to the axis of the can (the point of the solid arrow of Figure 9 and a plane that passes through the center line (a line along the solid arrow of Figure 8 of the resin-impregnated fiber bundle of the rear portion with respect to the bending portion and is perpendicular to the axis of the can. The preferable numerical range thereof can be applied to the above-described range.

[0074] With respect to the length of the bending, the length of the resin-impregnated fiber bundle of the rear portion with respect to the bending portion is not particularly limited, and is, for example, 10 mm to 300 mm.

[0075] In the present embodiment, at the bending portion, other material different from the resin-impregnated fiber bundle can be arranged between the resin-impregnated fiber bundle of the portion in front of the bending portion and the resin-impregnated fiber bundle of the portion behind the bending portion. As the shape of the other material, for example, a ring shape or a plate shape can be cited. By adopting such a shape, the other material can become the starting point of peeling.

[0076] Figure 20 is a schematic view showing a state in which the other material in a ring shape is arranged between the resin-impregnated fiber bundle of the portion in front of the bending portion and the resin-impregnated fiber bundle of the portion behind the bending portion in the mode in which the resin-impregnated fiber bundle of the portion in front of the bending portion is folded back under the resin-impregnated fiber bundle of the portion behind the bending portion and fixed as described in Figure 7 Figure 20 In the present embodiment, at the bending portion, other material different from the resin-impregnated fiber bundle can be arranged between the resin-impregnated fiber bundle of the portion in front of the bending portion and the resin-impregnated fiber bundle of the portion behind the bending portion. As the shape of the other material, for example, a ring shape or a plate shape can be cited. By adopting such a shape, the other material can become the starting point of peeling.

[0077] Figure 21 is a schematic view showing a state in which the other material in a plate shape is arranged between the resin-impregnated fiber bundle of the portion in front of the bending portion and the resin-impregnated fiber bundle of the portion behind the bending portion in the mode in which the resin-impregnated fiber bundle of the portion behind the bending portion is folded back under the resin-impregnated fiber bundle of the portion in front of the bending portion and fixed as described in Figure 7 Figure 21 In the present embodiment, at the bending portion, other material different from the resin-impregnated fiber bundle can be arranged between the resin-impregnated fiber bundle of the portion in front of the bending portion and the resin-impregnated fiber bundle of the portion behind the bending portion. As the shape of the other material, for example, a ring shape or a plate shape can be cited. By adopting such a shape, the other material can become the starting point of peeling.

[0078] Figure 22 and Figure 23 is a schematic view showing a state in which the other material in a ring shape (in Figure 20 ) or the other material in a plate shape (in Figure 22 ) is fixed at the bending portion, and the surface layer is partially removed to expose the winding end portion in the can in the mode in which the other material is fixed at the bending portion as described in Figure 21 and Figure 23 As shown in Figure 22 and 23 , when the resin-impregnated glass fiber bundle is extracted for recycling, by using the other member as the starting point of peeling, the occurrence of tearing can be suppressed, and the winding end portion can be easily peeled.

[0079] As the material of the other material, a material that does not deform or deteriorate under heating at 250°C is preferable, and for example, a metal material such as aluminum, iron, or the like can be cited. In addition, in order to suppress the occurrence of the concave-convex of the can, the thickness of the other material is preferably thin.

[0080] Hereinafter, one aspect related to the present embodiment will be described in detail.

[0081] Hereinafter, the present embodiment will be described with reference to​​Figure 9 A configuration example of a tank according to the present embodiment will be described. Further, the following configuration example represents one aspect of the present embodiment and does not mean that the present embodiment is limited to the following configuration example.

[0082] Figure 9 is a sectional view showing a configuration example of a tank 100 as one aspect according to the present embodiment. Figure 9 is a 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 coincides with an axis passing through the center of a circle having a substantially cylindrical tank main body. The tank 100 can be used, for example, to fill a gas such as compressed hydrogen. For example, the tank 100 is mounted on a fuel cell electric vehicle in a state of being filled with compressed hydrogen in order to supply hydrogen to the fuel cell electric vehicle.

[0083] Figure 9 is a schematic sectional view along the axial direction of the tank 100 according to the present embodiment. The tank 100 is a hollow container centered on a central axis X and is a pressure vessel for storing a high-pressure fluid such as high-pressure hydrogen gas or high-pressure natural gas. As shown in Figure 9 the tank 100 has at least an inner liner 10 made of resin that accommodates a gas, a reinforcing layer 20 that covers the outer peripheral surface of the inner liner 10, and a protective layer 30 that covers the outer peripheral surface of the reinforcing layer 20. In addition, a valve-side joint 40 and a terminal-side joint 60 are provided at both ends of the tank 100, respectively. A valve 50 is mounted on the valve-side joint 40.

[0084] The inner liner 10 has a main body portion and two side end portions, forms an internal space for storing a gas, and has gas barrier properties that seal the internal space in such a manner that a gas such as hydrogen does not leak to the outside. The main body portion is a cylindrical portion that extends along the central axis X of the tank 100 shown in Figure 9 The side end portions are dome-shaped portions continuously formed on both sides of the main body portion, each of the side end portions decreases in diameter as it moves away from the main body portion, and an opening portion is formed at the center of the portion having the smallest diameter, and each of the opening portions is provided with the valve-side joint 40 and the terminal-side joint 60.

[0085] The inner liner 10 is formed of a resin having gas barrier properties. As examples of such a resin, polyethylene resin, polypropylene resin, or nylon resin, or the like can be given. As the resin, one kind alone can be used, or two or more kinds can be used in combination. In addition, the inner liner 10 can be formed by mixing a gas-impermeable material such as a hydrogen occlusion alloy into the above-described resin.

[0086] The reinforcing layer 20 is formed of a resin-impregnated carbon fiber bundle (carbon fiber reinforced plastic (CFRP)) including a carbon fiber bundle and a second matrix resin. The reinforcing layer 20 is configured in a manner that a resin-impregnated fiber bundle including a carbon fiber bundle and a second matrix resin is wound on the inner liner. The reinforcing layer 20 can be formed, for example, by winding the fibers of the resin-impregnated carbon fiber bundle in a circumferential winding and / or a spiral winding on the outer peripheral surface of the inner liner 10. The layer (carbon fiber reinforced plastic layer) 20 configured of the resin-impregnated carbon fiber bundle mainly has a function of reinforcing the inner liner 10 (reinforcing layer). As the second matrix resin impregnated in the carbon fiber bundle, for example, a thermosetting resin or a thermoplastic resin can be given. The carbon fiber can be prepared by a method known in the art. As the carbon fiber, as long as it is a material in which carbon is a main component, for example, a carbon fiber prepared using acrylic acid as a raw material, a carbon fiber prepared using pitch as a raw material, or a carbon fiber prepared using polyvinyl alcohol as a raw material, or the like can be given. Among them, a PAN-based carbon fiber prepared using polyacrylonitrile fiber as a raw material is preferred.

[0087] The protective layer 30 is configured of a first protective layer 30a and a second protective layer 30b. The first protective layer 30a is formed of a resin-impregnated glass fiber bundle (glass fiber reinforced plastic (GFRP)) in which a glass fiber bundle is used as a reinforcing fiber bundle, and is configured in a manner that a resin-impregnated fiber bundle including a glass fiber bundle and a first matrix resin is wound on the inner liner. Specifically, the first protective layer 30a is formed by winding the glass fibers of the resin-impregnated glass fiber bundle, for example, in a spiral winding and / or a circumferential winding on the outer peripheral surface of the reinforcing layer 20. As the first matrix resin impregnated in the glass fiber bundle, for example, a thermosetting resin or a thermoplastic resin can be given.

[0088] The protective layer 30 has the first protective layer 30a that covers the outer peripheral surface of the reinforcing layer 20, and the second protective layer 30b that covers the outer peripheral surface of the first protective layer 30a. The second protective layer 30b can be a layer that is formed by curing a portion of the first matrix resin impregnated in the glass fiber bundle in a state of exuding on the surface of the glass fiber reinforced plastic wound for forming the first protective layer 30a in a heat curing process after the winding is completed.

[0089] The first protective layer 30a is configured of a resin-impregnated fiber bundle including a glass fiber and a first matrix resin. As the first matrix resin contained in the first protective layer 30a, for example, the same material as the second matrix resin of the reinforcing layer 20 can be given. In addition, the first matrix resin contained in the first protective layer 30a can be the same material as the second matrix resin contained in the reinforcing layer 20, or can be a different material.

[0090] The second protective layer 30b contains a first matrix resin as a main material. As described above, the first matrix resin can be a substance that a portion of the first matrix resin impregnated in the glass fiber bundle of the first protective layer 30a exudes on the surface of the first protective layer 30a, and the content rate of the first matrix resin of the second protective layer 30b is higher than the content rate of the first matrix resin of the first protective layer 30a. Such a second protective layer 30b can be only the first matrix resin, or can contain a portion of the glass fiber separated from the first protective layer 30a.

[0091] In Figure 9 In the present embodiment, the valve-side joint 40 can be formed of, for example, stainless steel, can be composed of other metal such as aluminum, or can be made of resin. The valve 50 is formed with an external thread in the cylindrical portion, and closes the opening of the valve-side joint 40 by screwing with an internal thread formed on the inner side surface of the valve-side joint 40. The end-side joint 60 can be composed of, for example, aluminum, and is assembled in a state where a part thereof is exposed to the outside, and functions to guide heat inside the can to the outside.

[0092] The second matrix resin is independent of the first matrix resin, and for example, the same material as the first matrix resin can be given. As the second matrix resin, for example, a thermosetting resin or a thermoplastic resin can be given. As described above, the first matrix resin and the second matrix resin can be the same material, or can be different materials. The second matrix resin is preferably a thermosetting resin. As the thermosetting resin, for example, the thermosetting resin described with respect to the first matrix resin can be given. The second matrix resin can be used alone, or two or more kinds can be used in combination.

[0093] A layer (fiber-reinforced resin layer) composed of a fiber bundle impregnated with a resin can be formed, for example, by a filament winding method. A filament-wound molded product can be manufactured by, as necessary, parallelizing a plurality of reinforcing fiber bundles, impregnating them with a matrix resin, and winding at an appropriate angle to an appropriate thickness with tension applied to a rotating base or a mold.

[0094] Figure 10 is a schematic view of a state in which the second protective layer 30b of the can 100 shown in Figure 9 is a schematic view of a state in which the second protective layer 30b of the can 100 shown in Figure 10As shown, the end portion of the resin-impregnated glass fiber bundle (glass fiber reinforced resin) constituting the first protective layer 30a is fixed in a bent state by being hardened or cured. Therefore, when the resin-impregnated glass fiber bundle is extracted for recycling, by inserting a scraper or the like between the bent portion and the layer thereunder, the occurrence of tears can be suppressed, and the end portion of the winding can be easily peeled off. In addition, the end portion of the resin-impregnated carbon fiber bundle constituting the reinforcing layer (intermediate layer) 20 can also be fixed in a bent state by being hardened or cured. Thus, when the resin-impregnated fiber bundle constituting the intermediate layer is extracted, the end portion of the winding can also be easily peeled off.

[0095] As one aspect of the present embodiment, a method of recycling the reinforcing fiber from the tank involved in the present embodiment can also be cited. Hereinafter, the recycling method of the present embodiment will be described.

[0096] Figure 11 An example of a flowchart for explaining the method involved in the present embodiment is shown. As shown, the present embodiment includes at least a tank preparation step, a bent portion peeling step, and an extraction step. Hereinafter, each step will be described in detail. Figure 11

[0097] Tank preparation step

[0098] The recycling method involved in the present embodiment includes a step of preparing the tank involved in the present embodiment. That is, the recycling method involved in the present embodiment includes a step of preparing a tank having a bent portion in which the end portion of the winding of the resin-impregnated fiber bundle is fixed in a bent state, in the end portion of the winding of the resin-impregnated fiber bundle.

[0099] As the prepared tank, for example, a tank that is used for each use after manufacture and is then recycled, or a defective product or the like in the manufacturing stage can be cited.

[0100] Bent portion peeling step

[0101] Next, the recycling method involved in the present embodiment includes a step of peeling the bent portion of the end portion of the winding from the surface of the tank.

[0102] In the peeling step, as described above, the bent portion is peeled by inserting a tool such as a scraper between the bent portion and the layer thereunder. At this time, the bent portion formed by bending and fixing the resin-impregnated fiber bundle functions as a guide between the bent portion and the resin-impregnated fiber bundle present thereunder when the scraper or the like is inserted, so that the occurrence of tears can be suppressed, and the resin-impregnated fiber bundle can be easily peeled from the bent portion.

[0103] Extraction step

[0104] ​The recycling method according to the present embodiment includes a step of stretching the peeled-off winding end portion, and extracting the resin-impregnated fiber bundle.

[0105] The extraction step is preferably a step of extracting the resin-impregnated fiber bundle while applying a heating treatment to the can. The temperature of the heating treatment is preferably equal to or higher than the glass transition temperature of the resin (first matrix resin) and lower than the thermal decomposition initiation temperature, and lower than the thermal deterioration temperature of the reinforcing fiber.

[0106] By the heating treatment, thermal decomposition of the resin (first matrix resin) and reduction in strength of the reinforcing fiber can be suppressed, and the resin in the resin-impregnated fiber bundle can be softened. Since the can is heated at a temperature equal to or higher than the glass transition temperature of the resin, the resin in the resin-impregnated fiber bundle is softened. By performing the extraction step in a state where the resin is softened, the resin-impregnated fiber bundle can be easily extracted. Specifically, the resin-impregnated fiber bundle can be extracted from the can with a smaller tension. By extracting with a small tension, breakage or damage of the reinforcing fiber, and the like, can be suppressed. In addition, by heating the can at a temperature lower than the thermal decomposition initiation temperature, thermal decomposition of the resin can be suppressed. By suppressing thermal decomposition of the resin, excessive deformation or carbonization of the resin can be suppressed, and as a result, even in the case where a dissolution treatment is performed in a subsequent step, the resin in the resin-impregnated fiber bundle can be easily dissolved. In addition, by suppressing thermal decomposition of the resin, reduction in strength of the resin can be suppressed, and thus the extracted resin-impregnated fiber bundle can be directly used for other purposes or subjected to desired processing (cutting, etc.) without passing through a resin removal step. Furthermore, by performing the heating treatment at a temperature lower than the thermal deterioration temperature of the reinforcing fiber, thermal deterioration of the reinforcing fiber can be suppressed, and reduction in strength of the reinforcing fiber can be suppressed.

[0107] In the present embodiment, "extracting the resin-impregnated fiber bundle" means extracting the resin-impregnated fiber bundle from the can in a continuous state, and also includes the concept of peeling the resin-impregnated fiber bundle from the can. In one embodiment, since the resin-impregnated fiber bundle is extracted in a state where the resin in the can is softened by heating, the resin-impregnated fiber bundle can be easily extracted. When the resin-impregnated fiber bundle is extracted from the can, peeling can be performed using a blade-like jig. By abutting the blade-like jig against a portion between the resin-impregnated fiber bundle and the surface of the can (resin portion) to cut the joint between the can and the resin-impregnated fiber bundle (resin portion), the resin-impregnated fiber bundle can be easily peeled.

[0108] The method of extracting the resin-impregnated fiber bundle is not particularly limited, and for example, the winding end portion of the resin-impregnated fiber bundle can be directly or indirectly connected to a winding roller, and extracted by rotating the roller.

[0109] The heat treatment can be performed, for example, in a heat treatment chamber. The pot is heated in the heat treatment chamber to soften the matrix resin of the pot. The heat treatment chamber can be a heating furnace or a heating device having a space configured to be able to introduce and / or discharge a heating medium to and / or from the inside.

[0110] As a method of extracting the resin impregnated fiber bundle while performing heat treatment on the pot, for example, Figure 12 As illustrated in FIG. 6, for example, a method of arranging the pot in the heat treatment chamber and extracting a part of the resin impregnated fiber bundle from the heat treatment chamber while performing heat treatment can be given. The resin impregnated fiber bundle can be carried to the outside from a carrying outlet provided to a part of the heat treatment chamber, for example. The transport of the resin impregnated fiber bundle can be performed continuously by a transport roller, for example.

[0111] In one embodiment in which glass fibers are used as the reinforcing fibers, the temperature of the heat treatment is equal to or higher than the glass transition temperature of the first matrix resin and lower than the thermal decomposition start temperature, and is lower than the thermal deterioration temperature of the glass fibers. In one embodiment in which carbon fibers are used as the reinforcing fibers, the temperature of the heat treatment is equal to or higher than the glass transition temperature of the first matrix resin and lower than the thermal decomposition start temperature, and is lower than the thermal deterioration temperature of the carbon fibers.

[0112] The thermal decomposition start temperature of the resin can be measured using a thermogravimetric measurement device.

[0113] In one embodiment, the thermal decomposition start temperature is preferably a temperature at which 5% weight reduction is shown in a weight change chart of a thermogravimetric analysis obtained by raising the temperature of the resin from 30°C to 550°C at a rate of 5°C / minute in a nitrogen atmosphere. The thermal decomposition start temperature is preferably a temperature at which 3% weight reduction is shown in a weight change chart of a thermogravimetric analysis obtained by raising the temperature of the resin from 30°C to 550°C at a rate of 5°C / minute in a nitrogen atmosphere. The thermal decomposition start temperature is preferably a temperature at which 1% weight reduction is shown in a weight change chart of a thermogravimetric analysis obtained by raising the temperature of the resin from 30°C to 550°C at a rate of 5°C / minute in a nitrogen atmosphere. It is generally considered that the above-described thermal decomposition start temperature in a nitrogen atmosphere is a temperature at which the decomposition of the main chain and / or side chain of the resin starts.

[0114] In one embodiment, the thermal decomposition onset temperature is preferably the temperature at which 5% weight reduction is shown in a thermogravimetric analysis weight change chart obtained by raising the temperature of the resin from 30°C to 550°C at a rate of 5°C / minute in an atmospheric atmosphere. Preferably, the thermal decomposition onset temperature is the temperature at which 3% weight reduction is shown in a thermogravimetric analysis weight change chart obtained by raising the temperature of the resin from 30°C to 550°C at a rate of 5°C / minute in an atmospheric atmosphere. Preferably, the thermal decomposition onset temperature is the temperature at which 1% weight reduction is shown in a thermogravimetric analysis weight change chart obtained by raising the temperature of the resin from 30°C to 550°C at a rate of 5°C / minute in an atmospheric atmosphere. Generally, in heating in an atmosphere, oxidative decomposition proceeds by oxygen contained in the atmosphere, and therefore, the thermal decomposition onset temperature determined in an atmospheric atmosphere is lower than the thermal decomposition onset temperature determined in a nitrogen atmosphere, assuming the same weight reduction rate.

[0115] In one embodiment using glass fibers as the reinforcing fibers, by heating the tank at a temperature lower than the thermal deterioration temperature of the glass fibers, the decrease in strength of the glass fibers can be suppressed. In the case of heat treatment of the glass fibers in an atmosphere, the thermal deterioration temperature of the glass fibers can be defined as the lowest temperature at which the tensile strength decreases by 1% or more. By measuring the tensile strength of the glass fibers used in the resin-impregnated fiber bundle before and after the heat treatment, the decrease in strength can be calculated.

[0116] In one embodiment using carbon fibers as the reinforcing fibers, by heating the tank at a temperature lower than the thermal deterioration temperature of the carbon fibers, the decrease in strength of the carbon fibers can be suppressed. In the case of heat treatment of the carbon fibers in an atmosphere, the thermal deterioration temperature of the carbon fibers can be defined as the lowest temperature at which the tensile strength decreases by 1% or more. By measuring the tensile strength of the carbon fibers used in the resin-impregnated fiber bundle before and after the heat treatment, the decrease in strength can be calculated.

[0117] In one embodiment, the temperature of the heat treatment is preferably 100°C or higher, preferably 120°C or higher, preferably 140°C or higher, preferably 160°C or higher, preferably 180°C or higher, preferably 200°C or higher. In addition, the temperature of the heat treatment is preferably lower than 400°C, preferably 390°C or lower, preferably 380°C or lower, preferably 370°C or lower, preferably 360°C or lower, preferably 350°C or lower, preferably 340°C or lower, preferably 330°C or lower, preferably 320°C or lower, preferably 310°C or lower, preferably 300°C or lower, preferably 290°C or lower, preferably 280°C or lower. In the case where the temperature of the heat treatment is 100°C or higher, the resin can be effectively softened in the resin-impregnated fiber bundle. In the case where the temperature of the heat treatment is lower than 400°C, the thermal decomposition of the resin in the resin-impregnated fiber bundle can be easily suppressed, and the deterioration of the reinforcing fiber such as glass fiber or carbon fiber can also be easily suppressed. The upper limit value and / or the lower limit value of these numerical ranges can be arbitrarily combined to define a preferable range.

[0118] As one example, the glass transition temperature of the epoxy resin is about 100°C to 200°C, and the thermal decomposition start temperature of the epoxy resin is about 240°C to 360°C. If the heating is performed at a temperature higher than the thermal decomposition start temperature, the thermal decomposition of the resin is excessively caused, and the strength of the resin is greatly reduced. In addition, the resin is excessively deformed or carbonized, and the resin is difficult to be dissolved and removed by the dissolving solution. Figure 13A shows the weight change chart of the thermogravimetric analysis of the epoxy resin as one example, in which the resin is heated from 30°C to 550°C at a rate of 5°C / minute in a nitrogen atmosphere. In Figure 13A , the temperature at which 5% weight reduction is shown is about 350°C, and this temperature can be defined as the thermal decomposition start temperature. In addition, Figure 13B shows the weight change chart of the thermogravimetric analysis of the epoxy resin as one example, in which the resin is heated from 30°C to 550°C at a rate of 5°C / minute in an air atmosphere. In Figure 13A and Figure 13B , the inflection point is also shown. In Figure 13BIn the present embodiment, the temperature at which 5% weight reduction is shown is 340°C, and this temperature can be defined as the thermal decomposition start temperature. As described above, in heating in the atmosphere, oxidative decomposition by oxygen contained in the atmosphere proceeds, and thus the thermal decomposition start temperature determined in the atmosphere is lower than the thermal decomposition start temperature determined in a nitrogen atmosphere, when the weight reduction rate is the same. When the temperature is higher than the thermal decomposition start temperature, thermal decomposition of the resin excessively proceeds, and decomposition of the main chain and / or side chain of the resin excessively proceeds, and depending on the case, carbonization of the resin can occur. If such thermal decomposition occurs, it is difficult to remove the resin by dissolving the resin with a dissolving solution. In addition, since the strength of the resin decreases, the resin cannot be recycled by recycling the fiber bundle itself. On the other hand, in the range from the glass transition temperature defined in one embodiment or more and lower than the thermal decomposition start temperature, thermal decomposition is suppressed and the resin is softened, and thus by extracting the resin-impregnated fiber bundle in this state, a high-quality continuous resin-impregnated fiber bundle can be easily obtained. Thermogravimetric analysis is a method of measuring the change in weight when the temperature of a substance is changed according to a predetermined program. In one embodiment, thermogravimetric analysis can be performed, for example, by disposing a test piece of about 10 mg in an aluminum, alumina, or platinum container, and measuring the change in weight when the temperature is increased at a certain heating rate (5°C / min).

[0119] From the viewpoint of more effectively suppressing thermal decomposition of the resin, the temperature of the heat treatment is preferably a temperature of 1°C or more lower than the thermal decomposition start temperature, preferably a temperature of 5°C or more lower than the thermal decomposition start temperature, preferably a temperature of 10°C or more lower than the thermal decomposition start temperature, preferably a temperature of 15°C or more lower than the thermal decomposition start temperature, preferably a temperature of 20°C or more lower than the thermal decomposition start temperature, preferably a temperature of 25°C or more lower than the thermal decomposition start temperature, and preferably a temperature of 30°C or more lower than the thermal decomposition start temperature.

[0120] Figure 14 is a graph showing the thermal properties of carbon fibers, which are one example of reinforcing fibers, and shows the strength ratio (tensile strength after heating / tensile strength before heating) when the carbon fibers are heated in the atmosphere for a predetermined time (horizontal axis) at a predetermined temperature (300°C, 400°C, 500°C). As shown in Figure 14 It is known that the strength of the carbon fibers does not decrease even when the carbon fibers are heated at 400°C. On the other hand, if the carbon fibers are heated at the temperature of the heat treatment of the related art, that is, 500°C, the strength decreases. It is considered that this is due to oxidative degradation of the carbon fibers by heat and oxygen. It is generally considered that the thermal decomposition start temperature of the resin is lower than the thermal degradation temperature of the carbon fibers.

[0121] Figure 15 is a graph showing the tensile shear strength ratio of a resin (epoxy resin) at a predetermined temperature. Specifically, Figure 15This represents the tensile shear strength ratio (tensile shear strength at heating / tensile shear strength before heating (strength at 23°C)) at predetermined temperatures (23°C, 100°C, 150°C, 250°C, horizontal axis), vertical axis, marked with ●. Additionally, the dashed line from 250°C to 350°C represents an imaginary curve. Furthermore, tensile shear strength is as follows... Figure 16 The diagram illustrates the strength at which the bonded joint fractures when two boards are bonded together with resin, determined by a shear stress applied under a load that causes the bonded parts to shift in opposite directions. Figure 15 As shown, the tensile shear strength decreases with increasing resin heating temperature. When the tensile shear strength is reduced, the resin-impregnated fiber bundles can be easily extracted. For example, at a heating temperature of 150°C, the tensile shear strength ratio is 0.2 or less, and compared to the tensile shear strength before heating, the tensile shear strength during heating is 20% or less, indicating that the resin-impregnated fiber bundles can be extracted with less force. In this embodiment, the heat treatment temperature is preferably a temperature where the tensile shear strength ratio is 20% or less, preferably a temperature where the tensile shear strength ratio is 15% or less, preferably a temperature where the tensile shear strength ratio is 10% or less, and preferably a temperature where the tensile shear strength ratio is 5% or less.

[0122] In this embodiment, the can is typically not crushed or pulverized. Only the cylindrical portion of the can may be used. Metal parts and the like inside the can can be removed before or after the heating process.

[0123] There are no particular limitations on the heating method used in the embodiments. For example, heating in the atmosphere can be cited as a heating method. Heating in the atmosphere is simple to perform and cost-effective. In particular, it is effective in suppressing the deterioration of carbon fibers even in the presence of oxygen, such as in the atmosphere. Alternatively, the heating treatment can be performed using superheated steam. By using superheated steam, the ratio of oxygen-containing air in the treatment atmosphere can be reduced, thus effectively suppressing the decomposition and damage of the reinforcing fibers. For example, the heating treatment can be performed by introducing atmospheric superheated steam into an atmospheric pressure reaction vessel. Furthermore, there are no particular limitations on the heating treatment; it can be performed under an inert atmosphere such as nitrogen. Heating treatment can be performed while supplying heated superheated steam and / or an inert gas (nitrogen, etc.) to the heat treatment chamber.

[0124] The recycling method according to the present embodiment can include a step of removing the resin from the resin-impregnated fiber bundle to obtain the reinforcing fiber. The method of removing the resin from the resin-impregnated fiber bundle is not particularly limited, and examples of the method include dissolution removal using a dissolving solution. By using a dissolving solution for dissolution removal, the reinforcing fiber (e.g., glass fiber or carbon fiber) can be prevented from deteriorating.

[0125] Removal step

[0126] The recycling method according to the present embodiment can include a step of removing the resin from the resin-impregnated fiber bundle to obtain the reinforcing fiber. The method of removing the resin from the resin-impregnated fiber bundle is not particularly limited, and examples of the method include dissolution removal using a dissolving solution. By using a dissolving solution for dissolution removal, the reinforcing fiber (e.g., glass fiber or carbon fiber) can be prevented from deteriorating.

[0127] Hereinafter, a dissolution removal step using a dissolving solution as one example of the step of removing the resin will be described.

[0128] The dissolution removal step is a step of removing the resin from the extracted resin-impregnated fiber bundle by dissolving the resin with a dissolving solution.

[0129] In one embodiment, the resin in the extracted resin-impregnated fiber bundle is removed by the dissolution removal step. By bringing the resin-impregnated fiber bundle into contact with a dissolving solution, the resin can be dissolved and removed. By dissolution removal, stress caused by heat can be avoided, and the reinforcing fiber (e.g., glass fiber or carbon fiber) can be prevented from deteriorating. Specifically, the reinforcing fiber is less likely to deteriorate by removal with a dissolving solution than by removal with thermal decomposition. In addition, in one embodiment, since excessive deformation and carbonization of the resin are suppressed in the extraction step under heating as a preceding step, the resin in the resin-impregnated fiber bundle can be effectively dissolved.

[0130] The dissolution of the resin is performed using a dissolving solution capable of dissolving the resin in the resin-impregnated fiber bundle. The dissolving solution is not particularly limited as long as it is a dissolving solution capable of dissolving the resin, and for example, includes at least one liquid selected from an acidic solution, an organic solvent, hydrogen peroxide water, and an ionic liquid. These liquids can dissolve or swell the resin, and can effectively remove the resin. The dissolving solution can be used alone or in combination of two or more.

[0131] As the acidic solution, for example, phosphoric acid or sulfuric acid, etc. can be given. As the acidic solution, a solution containing sulfuric acid (for example, a concentration of 90 mass% or more) as described in Japanese Patent Application Publication No. 2020-37638, a solution containing phosphoric acid as described in Japanese Patent Application Publication No. 2020-50704, etc. can be given. The acidic component can be used alone with one kind or can be used in combination with two or more kinds. For example, by impregnating the resin impregnated fiber bundle in concentrated sulfuric acid, the resin can be dissolved and removed. The temperature of the concentrated sulfuric acid can be, for example, 100 to 300°C. In addition, no substantial decrease in strength was found in the carbon fiber after the resin was removed by the dissolving solution.

[0132] As the organic solvent, for example, an aliphatic hydrocarbon-based solvent, an aromatic hydrocarbon-based solvent, an alcohol-based solvent, a ketone-based solvent, an ether-based solvent, an amide-based solvent, or an ester-based solvent, etc. can be given. The organic solvent can be used alone with one kind or can be used in combination with two or more kinds. As the aliphatic hydrocarbon-based solvent, for example, pentane, hexane, heptane, or octane, etc. can be given. As the aromatic hydrocarbon-based solvent, for example, benzene, toluene, or xylene, etc. can be given. As the organic solvent containing two or more components, for example, petroleum ether or volatile oil, etc. can be given. A decomposition catalyst can also be contained in the organic solvent. As the decomposition catalyst, for example, an alkali metal compound as described in Japanese Patent Application Publication No. 2020-45407 can be given.

[0133] As the ionic liquid, for example, an ionic liquid containing at least one cation selected from the group consisting of an imidazole-based, a pyridine-based, a pyrrolidine-based, a quaternary ammonium-based, and a quaternary phosphonium-based cation as the cation can be given. The ionic liquid can be used alone with one kind or can be used in combination with two or more kinds.

[0134] The dissolution and removal of the resin is performed by bringing the dissolving solution into contact with the resin impregnated fiber bundle. As the method of bringing the dissolving solution into contact with the resin impregnated fiber bundle, there is no particular limitation, and for example, an impregnation method, a die coating method, a bar coating method, a roll coating method, or a gravure coating method, etc. can be given. Among these, the impregnation method is preferred. Specifically, the dissolving solution can be brought into contact with the reinforcing fiber by transporting the resin impregnated fiber bundle with a roll in a manner of being impregnated in the dissolving solution disposed in a bath. In one embodiment, the resin impregnated fiber bundle can be impregnated in the dissolving solution while the extracted resin impregnated fiber bundle is transported with a transport roll or the like.

[0135] The degree of dissolution of the resin in the dissolution and removal process can be adjusted by the kind of the dissolving solution, the processing temperature, or the processing time, etc. The processing time can be adjusted by the transport speed of the resin impregnated fiber bundle, for example. There is no particular limitation on the processing time, and it can be appropriately set depending on the kind of the dissolving solution or the resin, etc.

[0136] The temperature of the dissolving solution (liquid temperature) can be appropriately set in consideration of the degree of removal of the resin. The temperature of the dissolving solution (liquid temperature) is, for example, 20°C or higher, 40°C or higher, 60°C or higher, 80°C or higher, and is, for example, 300°C or lower, 250°C or lower, 200°C or lower, 150°C or lower, 100°C or lower.

[0137] The resin can be removed by dissolving by spraying the dissolving solution into the resin-impregnated fiber bundle. That is, by bringing the dissolving solution into contact with the resin-impregnated fiber bundle by applying a spraying pressure to the dissolving solution, the resin in the resin-impregnated fiber bundle can be removed using the spraying pressure. The spraying device for spraying the dissolving solution is not particularly limited, and, for example, a high-pressure cleaning device or the like can be used.

[0138] The nozzle pressure at the time of spraying the dissolving solution is preferably 1 MPa or higher, preferably 5 MPa or higher, preferably 8 MPa or higher, and preferably 10 MPa or higher. If the pressure is the above, the resin can be effectively removed from the resin-impregnated fiber bundle. In addition, the nozzle pressure is preferably 30 MPa or lower, preferably 25 MPa or lower, preferably 22 MPa or lower, and preferably 20 MPa or lower. If the pressure is the above, the reinforcing fibers can be effectively prevented from being damaged by the dissolving solution. The distance between the nozzle at the time of spraying the dissolving solution and the resin-impregnated fiber bundle as the spraying target is preferably 10 to 200 cm, and more preferably 30 to 100 cm.

[0139] The resin can also be removed by dissolving by combining impregnation in the dissolving solution and spraying of the dissolving solution.

[0140] Sizing agent application step

[0141] The recycling method according to the present embodiment can include a step of attaching a sizing agent to the reinforcing fibers (for example, glass fibers or carbon fibers) obtained by removing the resin.

[0142] In the reinforcing fibers after the removal step, the resin is substantially entirely removed, and the bundle of reinforcing fibers is disentangled to become a single fiber. By applying a sizing agent to the reinforcing fibers, the bundle of reinforcing fibers can be easily wound in the form of a bobbin, and in addition, the occurrence of fuzz (fluff) of the reinforcing fibers and entanglement of the single fibers can be suppressed.

[0143] The sizing agent is not particularly limited, and, for example, an epoxy resin, a polyurethane resin, a vinyl ester resin, a polyamide resin, a nylon resin, a polyolefin resin (polyethylene or polypropylene), a polyester resin, a phenol resin, or a mixture thereof can be mentioned. Among them, an epoxy resin, a polyurethane resin, a vinyl ester resin, or a polyolefin resin is preferred, and an epoxy resin is more preferred. By using an epoxy resin as the sizing agent, the adhesion of the reinforcing fibers to the epoxy resin can be improved. The sizing agent can be used alone or in combination of two or more.

[0144] The sizing agent is imparted to the reinforcing fiber by bringing the sizing agent into contact with the reinforcing fiber. The method of imparting the sizing agent is not particularly limited, and for example, an impregnation method, a die coating method, a bar coating method, a roll coating method, or a gravure coating method can be given. Among these, the impregnation method is preferred. Specifically, the sizing agent can be imparted to the reinforcing fiber by transporting the reinforcing fiber with a roll in a manner of being impregnated in the sizing agent disposed in a sizing bath. The sizing agent is preferably dispersed or dissolved in water or an organic solvent such as acetone, and used in the form of a dispersion liquid or a solution. From the viewpoint of improving the dispersibility of the sizing agent and making the liquid stability good, a surfactant can be appropriately added to the dispersion liquid or the solution.

[0145] Winding process

[0146] The recycling method according to the present embodiment can include a process of winding the reinforcing fiber from which the resin is removed, which is obtained by the removing process. The process of winding the reinforcing fiber is performed after the removing process, and is preferably performed after the sizing agent imparting process in the case where the sizing agent imparting process is included.

[0147] For example, the winding can be performed using a winding roll. A driving device that provides a driving force for winding the reinforcing fiber is installed on the winding roll. In addition, a driving device that rotates the guide roll can be installed on a part of the guide roll. The smaller the winding tension, that is, the tension imparted to the reinforcing fiber, the better. By setting the winding tension within an appropriate range, it is possible to prevent the reinforcing fiber from being broken or winding deviation, and as a result, it is possible to obtain a longer continuous fiber.

[0148] In one embodiment, the process includes a step of extracting the resin-impregnated fiber bundle while performing heat treatment, a step of removing resin from the extracted and conveyed resin-impregnated fiber bundle, and a step of winding the resin-removed and conveyed reinforcing fiber. The resin-impregnated fiber bundle is extracted upstream, and the reinforcing fiber is wound downstream. Specifically, in one embodiment, the step of extracting the resin-impregnated fiber bundle under heat is performed upstream, and the step of winding the reinforcing fiber is performed downstream. Between the upstream extraction step and the downstream winding step, a removal step and, depending on the situation, a sizing agent application step are performed. In another embodiment, the step of extracting the resin-impregnated fiber bundle under heat is performed upstream, and the step of winding the reinforcing fiber is performed downstream. Between the upstream extraction step and the downstream winding step, a dissolution removal step and, depending on the situation, a sizing agent application step are performed. In this embodiment, the dissolution removal step can be performed immediately after the extraction step under heat, allowing the resin-impregnated fiber bundle to come into contact with a dissolving solution at a high temperature, thus enabling effective removal of resin using the dissolving solution. Specifically, a portion (preferably the end) of the resin-impregnated fiber bundle is removed from the tank and directly or indirectly connected to a winding machine. Tension is applied to the resin-impregnated fiber bundle using the winding machine to extract it as a continuous fiber. The extracted resin-impregnated fiber bundle is then passed through a dissolving solution to remove the resin. Finally, the reinforcing fibers obtained after resin removal are wound using the winding machine.

[0149] The process of removing part of the second protective layer

[0150] In this embodiment, prior to the peeling process at the bent portion, a step may be included to partially remove the second protective layer, which may be present on the first protective layer composed of resin-impregnated fiber bundles, in order to expose the bent portion at the winding end. That is, prior to the peeling process at the bent portion, this embodiment may include a step of removing a portion of the second protective layer to expose the winding end of the resin-impregnated fiber bundle.

[0151] Figure 10 This indicates that it will constitute Figure 9 This is a schematic diagram showing the state in which the second protective layer 30b on the surface of the can 100 is partially removed, exposing the first protective layer 30a. Additionally, Figure 10 The bottom image is Figure 10 The enlarged schematic diagram of the part enclosed by the dashed line in the upper side diagram is a schematic diagram showing the exposed end of the winding of the resin-impregnated fiber bundle.

[0152] The method for removing a portion of the second protective layer is not particularly limited, and can be any method that can remove a portion of the second protective layer to expose the end portion of the wound fiber bundle impregnated with the resin. Examples of the method for removing a portion of the second protective layer include laser treatment, dissolution treatment, heat treatment, and combinations thereof.

[0153] As described above, as the method for removing a portion of the second protective layer, laser treatment can be used. Examples of the laser used for the laser treatment include a carbon dioxide laser (CO2 laser), a YAG laser, a fiber laser, a semiconductor laser, and the like. Among them, a carbon dioxide laser is preferably used. The carbon dioxide laser is one type of gas laser, and is a laser that obtains continuous wave or high-output pulsed wave in the infrared region using carbon dioxide gas (carbon dioxide) as a medium. Laser in the 10.6 μm band, which is commonly used in carbon dioxide lasers, is easily absorbed by resins, particularly epoxy resins, and thus can effectively remove a portion of the second protective layer. On the other hand, although the carbon dioxide laser can effectively remove resins, it has a tendency to easily damage reinforcing fibers such as glass fibers or carbon fibers. Therefore, the carbon dioxide laser is preferably low output. For example, the average output of the continuous wave carbon dioxide laser is preferably 100 W or less, more preferably 50 W or less, still more preferably 40 W or less, and even more preferably 30 W or less.

[0154] Figure 17 is an image showing the state after the epoxy resin as the second protective layer was removed using a carbon dioxide laser (10.6 μm, continuous wave) of low output (average output: 30 W). It can be confirmed that by using a carbon dioxide laser of low output, the resin layer can be effectively removed without damaging the glass fibers in the first protective layer. In addition, when the second protective layer is removed using a laser, the first matrix resin in the first protective layer can also be partially removed.

[0155] Figure 18 is a graph showing the relationship between the number of laser irradiations and the etching depth (mm) when the epoxy resin as the second protective layer was removed using a carbon dioxide laser (10.6 μm, continuous wave) of low output (average output: 30 W). One laser irradiation is performed by scanning the entire object area with a continuous wave carbon dioxide laser having a predetermined beam cross-sectional area at a certain speed. In one laser irradiation, the laser is scanned in such a way that the same part is not irradiated as much as possible. Regarding the etching depth, the depth shown by the broken line indicates the distance from the surface of the second protective layer to the surface of the glass fiber bundle in the first protective layer, and the depth shown by the solid line indicates the distance from the surface of the second protective layer to the surface of the resin in the first protective layer. As shown in the graph, the etching depth increases with the number of laser irradiations. The etching depth is the distance from the surface of the second protective layer to the surface of the resin in the first protective layer. Figure 18As shown, the etching depth to the resin surface in the first protective layer becomes deeper as the number of irradiations increases, whereas the etching depth to the glass fiber bundle surface becomes constant from the number of irradiations of about 15. This indicates that by using a low-output carbon dioxide laser, the resin layer can be effectively removed without damaging the glass fibers in the first protective layer.

[0156] Figure 19A 、 Figure 19B 、 Figure 19C is an image of the surface of the pot at the number of irradiations of 10th, 20th, and 50th in the experiment shown in Figure 18 As shown, the etching depth to the resin surface in the first protective layer becomes deeper as the number of irradiations increases, whereas the etching depth to the glass fiber bundle surface becomes constant from the number of irradiations of about 15. This indicates that by using a low-output carbon dioxide laser, the resin layer can be effectively removed without damaging the glass fibers in the first protective layer.

[0157] As described above, as a method of removing a portion of the second protective layer, a dissolution treatment can be utilized. Specifically, a portion of the second protective layer can be removed by bringing a dissolving solution into contact with the portion of the second protective layer.

[0158] Dissolution of the first matrix resin constituting the second protective layer is performed using a dissolving solution capable of dissolving the resin. As the dissolving solution, there is no particular limitation as long as it is a dissolving solution capable of dissolving the first matrix resin, and for example, includes at least one liquid selected from the group consisting of an acidic solution, an organic solvent, hydrogen peroxide water, and an ionic liquid described above. These liquids can dissolve or swell the resin, and can effectively remove the resin. The dissolving solution can be used alone in one kind, or two or more kinds can be used in combination.

[0159] As a method of bringing a portion of the second protective layer into contact with a dissolving solution, there is no particular limitation, and for example, a method in which a sponge member or the like impregnated with a dissolving solution is disposed so as to be in contact with the target region of the second protective layer can be cited.

[0160] In the present embodiment, as a method of removing a portion of the second protective layer, a combination of a laser treatment and a dissolution treatment can also be utilized. For example, the resin can be roughly removed by a laser treatment first, and then the remaining resin can be removed by a dissolving solution.

[0161] As described above, as a method of removing a portion of the second protective layer, a heating treatment can be utilized. Specifically, a portion of the second protective layer can be removed by selectively heating it. From the viewpoint of thermally decomposing the resin, the temperature of the heating treatment can be, for example, 550°C or higher and 700°C or lower.

[0162] As a means of partially heating the second protective layer, there is no particular limitation, and for example, a heater can be used.

[0163] In the recycling method of reinforcing fibers according to the present embodiment, the reinforcing fibers suitable for recycling can be efficiently obtained.

[0164] In the recycling method of reinforcing fibers according to the present embodiment, the reinforcing fibers suitable for recycling can be efficiently obtained.

[0165] The upper limit value and / or the lower limit value of the numerical range described in the present specification can be combined arbitrarily to define a preferable range. For example, the upper limit value and the lower limit value of the numerical range can be combined arbitrarily to define a preferable range, the upper limit values of the numerical range can be combined arbitrarily with each other to define a preferable range, and the lower limit values of the numerical range can be combined arbitrarily to define a preferable range.

[0166] In the present specification, any reference to "one embodiment", "an embodiment", or "the embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. The appearances of the phrase "in one embodiment" or "an embodiment", or "in at least one embodiment" in various places in the specification are not necessarily all referring to the same embodiment.

[0167] The present embodiment has been described above in detail, but the specific structure is not limited to the present embodiment, and even if design changes are made within the scope of the gist of the present disclosure, they are included in the present disclosure.

Claims

1. A tank having a liner and a first protective layer disposed on an outer peripheral surface of the liner, the first protective layer being formed by winding a resin-impregnated fiber bundle containing a reinforcing fiber bundle and a first matrix resin on the liner, having a bent portion fixed in a state of being bent with the resin-impregnated fiber bundle at an end portion of winding of the resin-impregnated fiber bundle, and the resin-impregnated fiber bundle being bent in a direction different from a winding direction, a bending angle between a length direction of the resin-impregnated fiber bundle at a portion in front of the bent portion and a length direction of the resin-impregnated fiber bundle at a portion behind the bent portion being larger than 1 degree and smaller than 180 degrees when the bent portion is viewed from an outside of the tank in a radial direction.

2. The tank according to claim 1, wherein the bending angle is 1 degree or more and 150 degrees or less.

3. The tank according to claim 1, wherein the bending angle is 10 degrees or more and 120 degrees or less.

4. The tank according to claim 1, wherein the bending angle is 20 degrees or more and 90 degrees or less.

5. A tank having a liner and a first protective layer disposed on an outer peripheral surface of the liner, the first protective layer being formed by winding a resin-impregnated fiber bundle containing a reinforcing fiber bundle and a first matrix resin on the liner, having a bent portion fixed in a state of being bent with the resin-impregnated fiber bundle at an end portion of winding of the resin-impregnated fiber bundle, and the resin-impregnated fiber bundle being bent in a direction identical to a winding direction, a bending angle between a length direction of the resin-impregnated fiber bundle at a portion in front of the bent portion and a length direction of the resin-impregnated fiber bundle at a portion behind the bent portion being smaller than 1 degree when the bent portion is viewed from an outside of the tank in a radial direction.

6. A tank having a liner and a first protective layer disposed on an outer peripheral surface of the liner, the first protective layer being formed by winding a resin-impregnated fiber bundle containing a reinforcing fiber bundle and a first matrix resin on the liner, having a bent portion fixed in a state of being bent with the resin-impregnated fiber bundle at an end portion of winding of the resin-impregnated fiber bundle, and other material different from the resin-impregnated fiber bundle being disposed between the resin-impregnated fiber bundle at a portion in front of the bent portion and the resin-impregnated fiber bundle at a portion behind the bent portion at the bent portion.

7. The tank according to claim 6, wherein the other material is in a shape of a ring or a plate.

8. The tank according to any one of claims 1 to 7, further comprising a second protective layer composed of the first matrix resin provided on the first protective layer.

9. A method for recycling a reinforcing fiber, comprising the following steps: preparing the tank according to any one of claims 1 to 8; peeling the bent portion at the end portion of winding from a surface of the tank; and stretching the peeled end portion of winding to extract the resin-impregnated fiber bundle. ​ ​ ​ ​ ​ ​

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