Molded article

Abstract

The purpose of the present invention is to provide a molded article of a fiber-reinforced composite material with which a fiber material can be easily recovered and the application of the fiber material can be expanded at the time of reuse. A molded article 1 according to the present invention is a molded article of a fiber-reinforced composite material comprising: a resin material 10 that serves as a base material and that can be melted or decomposed; and a fiber material 20 that serves as a reinforcing material. The molded article 1 comprises a fiber low-density part 2 in which the density of the fiber material 20 in the molded article 1 is lower than that of the other parts. The fiber material 20 is embedded in the resin material 10 such that, when the end part 24 is positioned in the fiber low-density part 2, the end part 24 positioned in the fiber low-density part 2 can be identified after the resin material 10 is melted or decomposed, and that after the resin material 10 is melted or decomposed, the end part 24 positioned in the fiber low-density part 2 is taken out to remove the shape formed by the fiber material 24 and be recoverable.

Description

molded product

[0001] The present invention relates to a molded article of a fiber-reinforced composite material.

[0002] Conventionally, molded articles of fiber-reinforced composite materials using fiber materials such as carbon fiber and natural fiber as reinforcement have been provided. Furthermore, in recent years, from the viewpoint of effective utilization of resources, there has been an increasing demand for recycling of the fiber materials in fiber-reinforced composite materials. Furthermore, if it were possible to recover the fiber materials while maintaining their original length as they were molded, without breaking them as much as possible, the applications for reuse of the fiber materials could be expanded, and the recycling efficiency of the fiber materials could be increased.

[0003] Patent Document 1 discloses a fiber-reinforced composite material using a tape material. According to the technique of Patent Document 1, the fiber material can be recovered while maintaining its length. In the fiber-reinforced composite material of Patent Document 1, component data related to the components is stored in RFID (Radio Frequency Identification) or a three-dimensional code, and an RFID tag containing the data is attached to the molded product, making it possible to identify the recovery position of the tape material. According to the technique of Patent Document 1, the recovery position of the fiber material can be identified using an RFID reader or the like.

[0004] Special table 2019-529177 publication

[0005] Here, if the fiber material is recovered without being broken, the range of products that can be molded by utilizing the length of the fiber material will be expanded. Therefore, when recovering fiber material, it is desirable to recover the fiber material without breaking it as much as possible and while maintaining its original length at the time of molding in order to expand the applications for reuse. Here, in fiber-reinforced composite materials, the fiber material (such as knitting yarn or tape material) is densely packed to form the skeleton of the molded product, and it is not easy to find the end of the fiber material after melting or decomposing the resin material. On the other hand, when recovering the fiber material by melting or decomposing the resin material, there is a demand for quickly finding the end of the fiber material without using tools (e.g., RFID readers) to facilitate the recovery of the fiber material and improve the efficiency of the recovery work.

[0006] An object of the present invention is to provide a molded product of a fiber-reinforced composite material that allows easy recovery of the fiber material and enables the fiber material to be reused in a wider range of applications.

[0007] The inventors of the present application have investigated molded fiber-reinforced composite materials that allow easy recovery of the fiber material after melting or decomposing the resin material. Examples of molded fiber-reinforced composite materials include those molded by laminating prepregs in which a tape material is pre-impregnated with a resin material, and those molded by weaving a braiding yarn serving as a reinforcing material into a knitted fabric substrate and impregnating the knitted fabric substrate with a resin material. In the case of a molded product in which prepregs are laminated, after the resin material is melted or decomposed, the tape materials overlap, making it difficult to find the ends. Furthermore, when a knitted fabric substrate is used as a reinforcing material, the stitches are configured so that the braiding yarns are entangled, and after the resin material is melted or decomposed, the ends of the braiding yarns become entangled in the stitches, making it difficult to find the ends.

[0008] The present inventors have conducted extensive research and have found that providing a portion where the density of the fiber material is lower than other portions and locating the fiber end therein, thereby making the fiber end identifiable, makes it easier to find the fiber end after melting or decomposing the resin material. Specifically, in a molded product in which the fiber material can be recovered by pulling the end (e.g., the terminal end) of the fiber material after melting or decomposing the resin material to unravel the mesh or layered structure of the fiber material, providing a portion where the density of the fiber material is lower than other portions and locating the end therein, and configuring the end of the fiber material located therein so that it is identifiable after melting or decomposing the resin material, makes it easier to find the end after melting or decomposing the resin material. As a result, the present inventors have found that the end of the fiber material can be quickly found without the use of tools, reducing the workload of searching for the end of the fiber material, improving the efficiency of the fiber material recovery process, and facilitating the recovery of the fiber material. Based on this finding, the present invention was completed.

[0009] According to one aspect of the present invention provided based on the above findings, the following configuration can be adopted for a molded product: (1) A molded product of a fiber-reinforced composite material including a meltable or decomposable resin material serving as a base material, and a fiber material serving as a reinforcing material, the fiber material being embedded in the resin material in a continuous state so as to form a shape corresponding to the resin material, the molded product including a low-fiber-density portion in which the density of the fiber material is lower than that of other portions of the molded product, and the fiber material is embedded in the resin material such that at least one of the starting end and the ending end of the fiber material is located in the low-fiber-density portion, making the end located in the low-fiber-density portion identifiable after melting or decomposing the resin material, and the shape formed by the fiber material can be unraveled and recovered by removing the end located in the low-fiber-density portion after melting or decomposing the resin material.

[0010] In the molded product (1) described above, after melting or decomposing the resin material to expose the fiber material, removing the end (e.g., the terminal end) of the fiber material allows the fiber material to be recovered in a long state by unraveling the mesh or layering of the fiber material, and the end of the fiber material can be quickly found without using tools. For example, if the fiber material has a uniform density, the end of the fiber material will be difficult to find because it will blend in with other fiber material. In contrast, in the molded product (1) described above, the end of the fiber material is identifiably located in a low-density fiber material portion (low-fiber-density portion), making it easier to find the end of the fiber material without blending in with other fiber material. This reduces the workload of searching for the end of the fiber material after melting or decomposing the resin material, thereby improving the efficiency of the fiber material recovery process. As a result, the molded product (1) described above facilitates recovery of the fiber material, and allows the fiber material to be recovered in a long state, expanding the uses of the fiber material when reused and increasing recycling efficiency.

[0011] According to one aspect of the present invention, the molded product can have the following configuration: (2) In the molded product described in (1) above, the low-fiber-density portion includes a convex portion that forms a convex shape on the surface of the molded product, and the end of the fiber material is located at the convex portion that forms a convex shape on the surface of the molded product, so that the end that was located in the low-fiber-density portion after the resin material is melted or decomposed can be identified, and the position of the end that was located in the low-fiber-density portion before the resin material is melted or decomposed can be identified.

[0012] In the molded product of (2) above, the position of the end can be easily determined before the resin material is melted or decomposed. As a result, the molded product of (2) above further reduces the workload of searching for the end when recovering the fibrous material, making it easier to recover the fibrous material.

[0013] According to one aspect of the present invention, the molded product can have the following configuration: (3) In the molded product described in (2) above, the fiber material is configured so that the end of the fiber material is located in the convex portion that has a hook-like or annular convex shape on the surface of the molded product, thereby making it possible to identify the end that was located in the low-fiber-density portion after the resin material is melted or decomposed, and also making it possible to identify the position of the end that was located in the low-fiber-density portion before the resin material is melted or decomposed.

[0014] In the molded product of (3) above, a fastener or the like can be attached to the convex portion (the hook-shaped or annular portion) before the resin material is melted or decomposed. In the molded product of (2) above, if a fastener or the like is attached to the convex portion before the resin material is melted or decomposed, the end of the fiber material can be quickly set in a winding machine or the like after the resin material is melted or decomposed. As a result, in the molded product of (3) above, recovery of the fiber material becomes even easier.

[0015] According to one aspect of the present invention, the molded product can have the following configuration. (4) In the molded product described in any one of (1) to (3) above, the fiber material is a knitting yarn formed into a thread-like shape, the knitting yarn forms a knitted base material with continuous stitches in which the knitting yarn is looped, and the end portion is embedded in the resin material so that the end portion located in the low-fiber-density portion can be identified after melting or decomposing the resin material, and the knitted base material can be unraveled and recovered by removing the end portion located in the low-fiber-density portion after melting or decomposing the resin material.

[0016] In the molded product of (4) above, after the resin material is melted or decomposed to expose the knitting yarn, the terminal end of the knitting yarn is taken out, which makes it possible to unravel the stitches of the knitted fabric base material formed by the knitting yarn and recover the knitting yarn in a long state, and also makes it possible to quickly find the terminal end of the knitting yarn without using tools, etc. For example, when the density of the knitting yarn is uniform, the terminal end of the knitting yarn becomes mixed in with the knitting yarn of other parts and is difficult to find, but in the molded product of (4) above, the terminal end of the knitting yarn is located in a part where the density of the knitting yarn is low (low fiber density part), so the terminal end of the fiber material is less likely to be mixed in with the fiber material of other parts and is easier to find.

[0017] More specifically, when a knitted fabric substrate in which knitting yarn is knitted is used as a reinforcing material, the stitches are configured so that the knitting yarn becomes entangled, making the end portion difficult to find as it blends into the stitches. In contrast, in the molded product of (4) above, the density of the knitting yarn is lower around the end portion, making it easier to see the difference between the area around the end portion and the rest of the product. As a result, in the molded product of (4) above, the workload of searching for the end portion of the knitting yarn after melting or decomposing the resin material is reduced, and the efficiency of the knitting yarn recovery work can be improved. As a result, in the molded product of (4) above, the knitting yarn can be easily recovered, and the knitting yarn can be recovered in a long state, expanding the uses of the knitting yarn when reused and increasing recycling efficiency.

[0018] Furthermore, in the molded product of (4) above, the knitted fabric substrate has elasticity, so it fits easily into a mold and wrinkles are less likely to occur during molding. Therefore, the molded product of (4) above can improve the work efficiency when setting the substrate into a mold, and can also suppress the occurrence of wrinkles, compared to when cutting a fabric such as a woven fabric and then setting it into a mold.

[0019] According to one aspect of the present invention, the molded product can have the following configuration: (5) In the molded product described in (4) above, the low-fiber-density portion includes a portion with larger stitches than the stitches in the other portion, and the knitting yarn has a terminal end located in the portion with larger stitches than the stitches in the other portion, so that the terminal end located in the low-fiber-density portion can be identified after the resin material is melted or decomposed.

[0020] In the molded product of (5) above, the area around the end portion is coarsely knitted, making it easier to find and grasp. Specifically, different stitch sizes make the pattern appear different, making the low fiber density area easier to see, and the knitting yarn is sparse around the end portion (low fiber density area), preventing the user from grabbing areas other than the end portion. As a result, the molded product of (5) above makes it easier to find the end portion, improving work efficiency when recovering the fiber material.

[0021] According to one aspect of the present invention, the molded product can have the following configuration: (6) In the molded product described in (4) or (5) above, the knitting yarn is configured so that the terminal end provided with a knot formed by tying the knitting yarn is located in the low-fiber density portion where the density of the knitting yarn is lower than the other portions in the molded product, thereby making it possible to identify the terminal end that was located in the low-fiber density portion after the resin material is melted or decomposed.

[0022] The molded article of (6) above can prevent the vicinity of the end of the knitting yarn from fraying and makes the end easier to grip. As a result, the molded article of (6) above can reduce the portion of the knitting yarn that becomes unusable due to fraying and can further improve the work efficiency when recovering the knitting yarn.

[0023] According to one aspect of the present invention, the molded product can have the following configuration: (7) In the molded product described in (6) above, the knitting yarn is configured such that a ring-shaped portion is formed in the low-fiber density portion of the molded product where the density of the knitting yarn is lower than in other portions, and the terminal end portion, which is a one-sided knot with the knot at the base of the ring-shaped portion, becomes identifiable after the resin material is melted or decomposed.

[0024] According to the molded article of (7) above, the end of the knitting yarn becomes easier to find and easier to hook onto a winding machine, etc. As a result, the molded article of (7) above can further improve the work efficiency when collecting the knitting yarn for recycling.

[0025] According to one aspect of the present invention, the molded product can have the following configuration: (8) In the molded product described in any one of (4) to (7) above, the knitting yarn is formed into a knitted fabric base material having a continuous three-dimensional shape with looped stitches of the knitting yarn, and the terminal end is located in the low-fiber-density portion of the molded product where the density of the knitting yarn is lower than other portions, so that the terminal end located in the low-fiber-density portion can be identified after the resin material is melted or decomposed.

[0026] According to the molded article of (8), the knitted fabric substrate can be formed to fit the shape of the molded article. As a result, the molded article of (8) reduces the labor required to set the knitted fabric substrate in a mold and eliminates steps in the substrate, compared to when multiple knitted fabric substrates are arranged as reinforcing materials or when a woven fabric is used as a reinforcing material.

[0027] Furthermore, when a flat fabric material such as a woven fabric is used as a reinforcing material, the woven fabric must be cut to fit the three-dimensional shape of the molded product, resulting in waste material. In contrast, the molded product of (8) uses a knitted fabric substrate that can be formed to fit the shape of the molded product, thereby minimizing waste material. As a result, the molded product of (8) can reduce material yield.

[0028] The fibrous material contained in the molded article of the present invention may be any material usable as a reinforcing fiber material. For example, the fibrous material contained in the molded article of the present invention may be selected from various materials such as natural fiber, carbon fiber, and amilad fiber. The molded article may contain, for example, at least one fibrous material.

[0029] "Meltable or decomposable resin material" includes, for example, resin materials that can be melted by heating, resin materials that can be decomposed by chemical decomposition using chemicals, and resin materials that can be decomposed by superheated steam decomposition. For example, thermoplastic resins can be cited as resin materials that can be melted by heating. Furthermore, thermosetting resins can be cited as resin materials that can be decomposed by chemical decomposition using chemicals or by superheated steam decomposition. It is preferable that the resin material be recoverable by melting or decomposition. Various thermoplastic resins can be selected, for example, polyethylene, polypropylene, ABS resin, acrylic resin, polyamide, etc. Various thermosetting resins can be selected, for example, epoxy resin, vinyl ester resin, unsaturated polyester resin, etc.

[0030] The ratio (volume or weight ratio) of the resin material to the fiber material in the molded article of the present invention can be appropriately selected depending on the thickness and size of the molded article, the manufacturing method, and the like.

[0031] "So as to form a shape corresponding to the resin material" means, for example, that the fiber material forms the shape (skeleton) of the molded product. In other words, the fiber material is not, for example, used partially in the molded product, but rather forms the outer shape of the molded product. For example, if the fiber material is a knitting yarn substrate made by knitting yarn, this means that the knitting yarn substrate is shaped to fit the shape of the molded product. If the fiber material is a knitting yarn, this means that in the molded product, the knitting yarn (knitted fabric substrate) is shaped to fit the outer shape formed by the resin material. Furthermore, for example, if the fiber material is a tape material, this means that the tape material is shaped to fit the outer shape of the molded product.

[0032] "Continuous state" means, for example, that the fiber material is continuous from the beginning to the end (has an endless shape). Note that "continuous state" does not matter, for example, whether it is a single fiber material without joints, or whether it has a continuous length with a portion (seam) where multiple fiber materials are connected. In other words, "continuous fiber material" also includes, for example, a fiber material with a joint along the way. The fiber material may be configured, for example, so that it can be handled in a single state. Furthermore, it does not matter, for example, whether the fiber material is a single strand or a bundle of multiple fibers.

[0033] The "end of the fiber material" means, for example, at least one of the starting end and the ending end of the fiber material. That is, "at least one of the starting end and the ending end of the fiber material is located in the low fiber density portion" means, for example, a case where the starting end is located in the low fiber density portion, a case where the ending end is located in the low fiber density portion, or a case where both the starting end and the ending end are located in the low fiber density portion.

[0034] The "starting end" refers to, for example, one of the two end portions, the end that becomes the starting portion of the fiber material in a substrate formation process in which a fiber material (e.g., a knitting yarn) is formed into a knitted fabric substrate, or in a process in which a fiber material (e.g., a tape material) is molded into a shape that conforms to a mold. The "ending end" refers to, for example, one of the two end portions, the end that becomes the ending portion in a substrate formation process in which a fiber material is formed into a knitted fabric substrate, or in a lamination process in which fiber materials are laminated. Note that, for example, if the fiber material is a knitted fabric substrate, removing the ending end or the starting end causes the knitted fabric substrate to unravel and return to the knitting yarn. Also, for example, if the fiber material is a tape material, removing the ending end or the starting end causes the tape material that formed the outer shape of the molded product to unravel.

[0035] "The fiber material is embedded in the resin material so that the shape of the fiber material can be unraveled and recovered by removing the end portion located in the low-fiber density portion after melting or decomposing the resin material" means, for example, that when the fiber material is embedded in the resin material in a continuous state, the shape of the fiber material can be unraveled by removing the end portion after melting or decomposing the resin material. For example, if the fiber material is a knitting yarn and the knitting yarn forms a knitted substrate, removing the end portion (e.g., the terminal end) after melting or decomposing the resin material unravels the stitches of the knitted substrate, causing the knitting yarn to return to a thread-like form and allowing the knitting yarn to be recovered. Also, for example, if the fiber material is a tape material and the molded product is a tape material molded into a shape that conforms to a mold, removing the end portion after melting or decomposing the resin material means that the shape of the tape material can be unraveled and the tape material can be recovered.

[0036] "Knitting yarn" refers to, for example, a thread-like material (including a string-like material) that forms the stitches of a knitted fabric substrate. The thickness of the knitting yarn can be selected appropriately depending on, for example, the size and thickness of the molded product, the knitting machine used, etc. In this specification, anything that can be knitted using a knitting machine will be referred to as a "knitting yarn" regardless of its thickness. In other words, in this specification, "knitting yarn formed into a thread-like material" includes both a material with a thickness generally referred to as a "yarn" and a material with a thickness generally referred to as a "string."

[0037] A "knitted fabric substrate" is, for example, a substrate in which stitches formed by looping knitting yarn are continuously formed. More specifically, a knitted fabric substrate is, for example, a substrate in which a knitting yarn is continuously formed into a loop, and a knitting yarn is further passed through the looped portion to form a loop, and the looped portion (stitches) of the knitting yarn is continuously formed, thereby forming a knitted fabric. The knitted fabric substrate can be formed, for example, using a knitting machine.

[0038] "A knitted fabric substrate on which continuous stitches are formed by looping knitting yarn" means, for example, that the essential fiber material constituting the knitted fabric substrate is the knitting yarn. Note that the molded product of the present invention may also contain, for example, a reinforcing material that does not constitute stitches. That is, the knitted fabric substrate may be composed of, for example, one type of fiber material or may contain multiple types of fiber materials. For example, the knitted fabric substrate may be composed only of the knitting yarn, or may contain the knitting yarn and the inlay yarn. Furthermore, the knitted fabric substrate may contain, in addition to the knitting yarn, other yarn materials (such as bias yarn).

[0039] Furthermore, the knitted fabric substrate contained in the molded product may be, for example, one piece or multiple pieces. For example, the knitted fabric substrate contained in the molded product may be one piece of knitted fabric substrate. Furthermore, the molded product of the present invention may be, for example, molded by arranging multiple knitted fabric substrates so as to conform to the shape of the molded product. Furthermore, for example, the molded product of the present invention may be formed by laminating multiple knitted fabric substrates. Furthermore, the tape material contained in the molded product may be, for example, one piece or multiple pieces. For example, the molded product of the present invention may be molded using one tape material, or may be molded using multiple tape materials.

[0040] "A low-fiber-density portion in which the density of the fiber material in the molded article is lower than in other portions" means, for example, that the density of the fiber material in the molded article (before the resin material is melted or decomposed) is lower in the low-fiber-density portion than in other portions. In other words, "a low-fiber-density portion in which the density of the fiber material in the molded article is lower than in other portions" means, for example, that the low-fiber-density portion is a portion in which the volume occupied by the fiber material relative to the volume of the molded article is lower than in other portions. In other words, for example, the other portions and the low-fiber-density portion are demarcated by the boundary at the point where the density of the fiber material changes in the portion of the molded article containing the fiber material.

[0041] More specifically, the low fiber density portion refers to a portion in which the volume occupied by the fiber material is low relative to the total volume (volume of the molded product) of the resin material, fiber material, and other materials (such as film materials). An example of a low density fiber material is when the fiber material is a knitting yarn, and the knitted fabric substrate has partially large stitches (partially coarse stitches), resulting in a partially low density of the knitting yarn. Another example is when a hole without stitches is formed in the knitted fabric substrate, and the hole includes the vicinity of the end of the knitting yarn, resulting in a lower density of the knitting yarn in the hole compared to other portions (parts that are knitted).

[0042] To explain this using a specific example, if the fiber material is a knitting yarn, the terminal end of the knitting yarn can be placed in a convex portion formed in a convex shape in the low fiber density portion, and the stitches near the terminal end can be larger than in other portions (see Figure 1 (a)). With this configuration, the convex portion does not include stitches and the density of the knitting yarn is lower than in other portions, and the portion with larger stitches near the terminal end has a lower knitting yarn density than portions other than the low fiber density portion. In other words, the density of the knitting yarn is, in order of decreasing, "convex portion (low fiber density portion) < portion with larger stitches (low fiber density portion) < other portions other than the low fiber density portion."

[0043] Furthermore, for example, when the fiber material is a knitting yarn, the stitches in the portion where the end of the knitting yarn is arranged (low fiber density portion) may be larger than those in other portions (see FIG. 4(a)). With this configuration, the density of the knitting yarn in the low fiber density portion is lower than that in other portions.

[0044] Furthermore, for example, when the fiber material is a knitting yarn, a hole without stitches may be provided in the knitted fabric substrate in the portion where the end of the knitting yarn is to be placed (low fiber density portion), and the end of the knitting yarn may be placed in the hole (see FIG. 4(b)). With this configuration, since there are no stitches in the low fiber density portion, the density of the knitting yarn is lower than in other portions.

[0045] Furthermore, for example, when the fiber material is tape-shaped (tape material), one or both ends of the tape material may be covered with a film material or the like, and the amount of resin material may be increased near the ends of the tape material (see FIG. 5(a)). With this configuration, the proportion (density) of the tape material in the molded product is lower near the ends of the tape material (low fiber density portion) than in other portions. In other words, the density of the tape material is in descending order: "near the ends of the tape material (low fiber density portion) < other portions." Note that the material covering the ends of the tape material can be selected from a variety of materials, including resin films such as plastic films, and materials similar to the tape material.

[0046] The low-fiber-density portion may be provided, for example, only at the starting end, only at the terminal end, or at both the starting end and the terminal end. The low-fiber-density portion may have a lower fiber density than the other portions, and may be provided with a tag or be a different color from the other portions. The end of the fiber material may have a tag attached or be a different color from the other portions.

[0047] "Configured so that the end portion located in the low fiber density portion can be identified after the resin material is melted or decomposed" means, for example, that the end portion located in the low fiber density portion before the resin material is melted or decomposed can be identified from other portions after the resin material is melted or decomposed.

[0048] The fact that "the end portion located in the low fiber density portion is configured to be identifiable after the resin material is melted or decomposed" will be explained by giving specific examples of a first, second, third, and fourth example. Note that the first, second, and third examples are examples of molded articles in which the fiber material is formed as a knitted substrate, and the fourth example is an example in which the fiber material is a tape material and the tape material is laminated.

[0049] As a first example, in the case of a molded article in which a fiber material is formed as a knitted substrate, a portion with larger stitches than other portions can be provided, and the end portion can be configured to be located in the portion with larger stitches after the resin material is melted or decomposed (see FIGS. 1(b), 4(a), and 4(c)). With this configuration, after the resin material is melted or decomposed, it becomes possible to distinguish the stitches of other portions from the end portion and the portion where the end portion is located (the portion with larger stitches).

[0050] As a second example, in the case of a molded article in which the fiber material is formed as a knitted base material, a hole without stitches can be provided in the knitted base material, and the end portion can be configured to be located in the hole after the resin material is melted or decomposed (see FIG. 4(b)). With this configuration, after the resin material is melted or decomposed, it becomes possible to distinguish the other portion (the portion with stitches) from the end portion and the hole portion.

[0051] As a third example, in the case of a molded article in which a fiber material is formed as a knitted substrate, the end (e.g., the end where a knot is formed) can be configured to be located on the surface of the knitted substrate, and after the resin material is melted or decomposed, the end can be configured to be located on the surface of the knitted substrate (see FIG. 4(d)). With this configuration, after the resin material is melted or decomposed, it becomes possible to distinguish between the knitted substrate and the end of the knitting yarn.

[0052] As a fourth example, in the case of a molded product in which tape material is layered, the tape material can be layered at approximately regular intervals and in a path that forms approximately the same angle in the portions other than the end portions, while the tape material at the end portions can be arranged in a path that curves differently from the path formed by the tape material in the other portions (see FIG. 5(b)). With this configuration, after the resin material is melted or decomposed, the tape material in the other portions will be layered at approximately regular intervals and angles, while the end portions will form an angle different from the angle formed by the other portions. As a result, it is possible to distinguish the tape material in the other portions from the end portions.

[0053] The end of the knitting yarn may be covered with, for example, another member. For example, the end of the knitting yarn may be covered with another member, such as by attaching a tubular member or by being reinforced with a tape material. This configuration can prevent the end of the knitting yarn from fraying.

[0054] A "protruding portion" is, for example, a portion of the surface of a molded article that is protruding. The surface of a molded article refers to the surface of the outer layer of the molded article, regardless of whether it is the front or back surface of the product. The protruding portion may be formed in any shape, such as a dome-shaped protrusion on the surface of the molded article, a cylindrical protrusion, a hook-shaped protrusion, or a ring-shaped protrusion.

[0055] "Other parts" refers to, for example, the parts of the molded article that have the density of the fiber material that is most widely applied (the standard density used in most of the molded article). For example, if the fiber material is a knitting yarn, "other parts" refers to the parts of the knitted stitches that are most widely applied in the molded article (the standard knitted stitch size used in most of the molded article). Also, for example, if the fiber material is a tape material, "other parts" refers to the parts of the tape material that is most widely applied in the molded article (the spacing between adjacent tape materials in a plan view or the spacing between tape materials in a cross-sectional view). The density of the fiber material in the "other parts" may be, for example, uniform or sparse.

[0056] The density of the fiber material in the low-fiber-density portion does not necessarily have to be the lowest in the molded article, and the molded article of the present invention also includes, for example, a case where a portion other than the low-fiber-density portion has a lower density than the fiber material in the low-fiber-density portion.

[0057] When the fiber material is a knitted yarn, the phrase "the low-fiber density portion includes a portion where the stitches are larger than those in the other portions" means, for example, that the low-fiber density portion includes a portion where the stitches are larger than the stitch size most widely used in the molded product (the standard stitch size used in most of the molded product). Note that the stitches included in the low-fiber density portion do not necessarily have to be the largest in the molded product. In other words, the molded product of the present invention also includes, for example, a case where stitches larger than those in the low-fiber density portion are present in parts other than the low-fiber density portion.

[0058] When the fiber material is a tape material, the phrase "a low-fiber-density portion in which the density of the fiber material is lower than that of other portions of the molded product" means, for example, that the low-fiber-density portion includes a portion in which the spacing between the tape materials is greater than the spacing between the tape materials used over the widest area in the molded product (the standard spacing between the tape materials used in most of the molded product). Note that when the fiber material is a tape material, the density of the tape material in the low-fiber-density portion does not necessarily have to be the lowest in the molded product. In other words, the molded product of the present invention also includes a case in which, for example, a portion other than the low-fiber-density portion exists in which the density of the tape material is lower than the density of the tape material in the low-fiber-density portion.

[0059] The size of the stitches can be selected appropriately depending on the type, shape, size, etc. of the part. When the stitches are made larger in the low fiber density portion, it is desirable that the stitch sizes differ to an extent that the low fiber density portion and other portions can be visually recognized as different patterns. For example, the length of the knitting yarn constituting one stitch in the low fiber density portion is preferably 150% or more of the length of the knitting yarn constituting one stitch in the other portions. According to this configuration, the stitches in the low fiber density portion and the stitches in the other portions can be easily visually recognized as different patterns. Furthermore, the length of the knitting yarn constituting one stitch in the low fiber density portion is preferably 150% or more and 300% or less of the length of the knitting yarn constituting one stitch in the other portions. According to this configuration, the end of the knitting yarn can be easily found.

[0060] As described above, the molded article of the present invention includes a low-fiber-density portion and other portions. Furthermore, as described above, the other portions and the low-fiber-density portion may differ in fiber density to such an extent that they are visually recognizable as different patterns, for example, before the resin material is melted or decomposed. For example, when the fiber material is a knitting yarn, the low-fiber-density portion and the other portions may have a difference that is recognizable as visually different patterns, such as a portion with small stitches (the other portions) and a portion with large stitches (the low-fiber-density portion). Furthermore, when the fiber material is a knitting yarn, the low-fiber-density portion and the other portions may be visually recognizable as different fiber material densities, such as a difference between a portion including stitches (the other portions) and a convex portion including an end portion disposed on the surface of the knitted fabric substrate (the low-fiber-density portion). Furthermore, for example, when the fiber material is a tape material, it is preferable that the low fiber density portion and other portions be visible in a manner in which the density of the fiber material is different, such as a portion (other portion) where the tape material is arranged at approximately regular intervals and a convex portion (low fiber density portion) including an end portion arranged so as to be spaced apart from the other tape material by a film material or the like.

[0061] The low fiber density portion is defined, for example, in a molded product, within a range of a predetermined distance from the end of the fiber material. The predetermined distance is, for example, the length of the end. The predetermined distance is, for example, a length that allows the end of the fiber material to be gripped. The gripping of the end is performed, for example, by a gripping device. When the fiber material is a knitted substrate, the low fiber density portion can be defined, for example, as a portion that includes a length of fiber material that can be gripped from the end of the fiber material. When the fiber material is a knitting yarn, the low fiber density portion can be defined, for example, as a portion that includes a length of knitting yarn that can be gripped from the end of the knitting yarn. Furthermore, when the fiber material is a knitting yarn, the low fiber density portion can be defined, for example, as a portion where the stitches formed by the knitting yarn of a grippable length are larger than the stitches in other portions. Furthermore, when the fiber material is a tape material, the low fiber density portion can be defined, for example, as a portion that includes a length of tape material that can be gripped from the end of the tape material.

[0062] At least a portion of the low-fiber-density portion is provided, for example, so as to include at least a portion of the surface of the molded article. For example, at least a portion of the low-fiber-density portion is provided so as to include a raised portion of the surface of the molded article (e.g., a convex portion). At least a portion of the low-fiber-density portion may be provided, for example, inside the molded article. For example, if a position closer to the surface of the molded article in the thickness direction is defined as an upper layer and a position deeper than the upper layer is defined as a lower layer (inside the molded article), at least a portion of the low-fiber-density portion may be provided in the lower layer. For example, the low-fiber-density portion may be formed adjacent to another portion in the lower layer of the molded article. The low-fiber-density portion may also be provided in a portion of the thickness direction of the molded article. Furthermore, for example, the low-fiber-density portion may be provided throughout the entire thickness direction.

[0063] The molded article may be any part. For example, the molded article may be a boat part, a blade, a drone part, or the like. Furthermore, the molded article may be a finished product itself.

[0064] The manufacturing method of the molded product can be selected from various methods depending on the type of fiber material, the shape and size of the molded product, such as a method of setting fiber material that has not been impregnated with resin in a mold and injecting resin, or a method of stacking fiber material.

[0065] Examples of techniques for setting a fibrous material in a mold and injecting resin include the RTM (Resin Transfer Molding) method and the VaRTM (Vacuum Assimilated Resin Transfer Molding) method. The RTM method involves setting a fibrous material in a mold, closing a mold including an upper and lower mold, injecting resin into a cavity in the mold, impregnating the fibrous material with the resin in the mold, and allowing it to harden to form a molded product. The VaRTM method involves using only a lower mold, covering the upper surface with a film bag, and impregnating the fibrous material with resin by vacuum suction.

[0066] Examples of techniques for laminating fiber materials include tape winding, sheet winding, and autoclave. The tape winding method involves winding a tape-like prepreg, which is a fiber material impregnated with a resin, around a core metal called a mandrel, then wrapping it with heat-shrinkable tape, and heating the mandrel to harden it. The sheet winding method involves winding a sheet-like prepreg around a mandrel, then wrapping it with heat-shrinkable tape, and heating the mandrel to harden it. The autoclave method involves laminating sheet-like prepregs in a mold, and then using an autoclave (pressure vessel) to harden the resin while heating, pressurizing, and evacuating.

[0067] According to the present invention, it is possible to provide a molded product of a fiber-reinforced composite material that allows easy recovery of the fiber material and expands the applications of the fiber material when reused.

[0068] 1A and 1B are diagrams showing a molded product according to a first embodiment of the present invention; (a) is a schematic diagram showing a main part of the molded product, (b) is a diagram showing a state in which the resin material of the molded product has been melted, and (c) is a diagram showing the stitches of a knitted fabric substrate; (b) is a diagram showing a method for manufacturing the molded product of FIG. 1; (c) is a diagram showing a method for recovering material from the molded product of FIG. 1; (d) is a diagram showing a modified example of the molded product of FIG. 1; (e) is a diagram showing a main part of a molded product according to a second embodiment of the present invention;

[0069] Hereinafter, detailed descriptions of embodiments of the molded article of the present invention will be given with reference to the drawings. Note that the embodiments described below are merely examples. The present invention should not be construed as being limited in any way by the embodiments described below.

[0070] [First embodiment] The configuration of a molded article 1 according to a first embodiment of the present invention will be described with reference to Fig. 1. Fig. 1 is a schematic diagram showing a main part of the molded article 1, a state after the resin material of the molded article has been melted, and stitches 23a formed in a knitted fabric substrate 22 of the molded article 1.

[0071] The molded article 1 is a molded article of a fiber-reinforced composite material including a fiber material 20 serving as a reinforcing material and a resin material 10 serving as a matrix material. In the molded article 1 of this embodiment, a thermoplastic resin that can be melted by heating is used as the resin material 10. Furthermore, in the molded article 1 of this embodiment, natural fibers are used as the fiber material 20. As shown in FIG. 1( a ), the molded article 1 of this embodiment includes a plurality of knitted fabric substrates 22. Specifically, the molded article 1 is formed by stacking three knitted fabric substrates 22. Furthermore, in the molded article 1 of this embodiment, each knitted fabric substrate 22 has a three-dimensional shape that matches the shape of the molded article 1.

[0072] In the molded product 1 of this embodiment, the fiber material 20 is a braided yarn 21. The braided yarn 21 (fiber material 20) is embedded in the resin material 10 in a continuous state so as to form a shape corresponding to the resin material 10. More specifically, the braided yarn 21 has a continuous thread-like shape and is formed as a knitted fabric substrate 22, which will be described later. That is, in the molded product 1, the braided yarn 21 (knitted fabric substrate 22) is embedded in the resin material 10 over most of the molded product 1 that forms the outer shape of the product.

[0073] The knitting yarn 21 (fiber material 20) is embedded in the resin material 10 so that the shape formed by the knitting yarn 21 (knitted fabric substrate 22) can be unraveled and recovered by taking out the terminal end 24a of the knitting yarn 21. Furthermore, the knitting yarn 21 is configured so that the terminal end 24a can be identified when the resin material 10 is melted, and the terminal end 24a is located in the low fiber density portion 2.

[0074] As described above, in the molded article 1 of this embodiment, the fiber material 20 is the knitting yarn 21 formed into a thread shape. The knitting yarn 21 is formed by twisting bundled natural fibers. The knitting yarn 21 is also formed as a knitted fabric substrate 22.

[0075] The knitted fabric base material 22 will be described in detail with reference to Fig. 1(c) . In the following description, the direction in which the knitting yarn 21 is supplied (the horizontal direction in Fig. 1(c) ) may be simply referred to as the "course direction X," and the direction intersecting the course direction X may be simply referred to as the "wale direction Y" (the vertical direction in Fig. 1(c) ).

[0076] 1(c), the knitting yarn 21 forms loop-shaped stitches 23a. Specifically, the knitting yarn 21 forms a plurality of stitches 23a aligned in the course direction X. The knitting yarn 21 also forms crossover portions 23b between the stitches 23a. In this way, the knitting yarn 21 is formed as a knitted fabric base material 22 with a plurality of stitches 23a formed in each of the course direction X and the wale direction Y.

[0077] As shown in Fig. 1(a), the molded article 1 has a low fiber density portion 2. The low fiber density portion 2 is a portion where the density of the knitting yarn 21 is lower than other portions. Also, as shown in Fig. 1(a), the low fiber density portion 2 includes a convex portion 3 in which the surface F of the molded article 1 is convex. In the molded article 1 of this embodiment, the convex portion 3 is shaped so that the surface F of the molded article 1 is raised in a dome shape.

[0078] As shown in Fig. 1(a), in the molded product 1 of this embodiment, a knot 27 is provided near the terminal end 24a by tying the knitting yarn 21. Also, as shown in Fig. 1(a), in the molded product 1 of this embodiment, a ring-shaped portion 28 is formed near the terminal end 24a, where the knitting yarn 21 is looped, and the knot 27 is formed at the base of the ring-shaped portion 28, forming a one-sided knot.

[0079] Next, a more detailed description will be given of the low-fiber-density portion 2. In the molded article 1 of this embodiment, the low-fiber-density portion 2, which is a portion in which the density of the knitting yarn 21 in the molded article 1 is lower than in other portions, includes a portion (open knit portion 26) in which the stitches 23a are larger than in other portions, and a convex portion 3.

[0080] Specifically, as shown in FIG. 1( a), the portion of the knitted fabric substrate 22 near the terminal end 24a forms a loosely knitted portion 26 in which the stitches 23a are larger than those in other portions. Note that in the knitted fabric substrate 22, the portion other than the loosely knitted portion 26 (the densely knitted portion 25) has stitches 23a of a standard size for the knitted fabric substrate 22. Therefore, the loosely knitted portion 26 has larger stitches 23a than the densely knitted portion 25, and can be said to be a portion where the density of the knitting yarn 21 in the molded product 1 is lower than that of the densely knitted portion 25. In other words, the loosely knitted portion 26 is included in the low fiber density portion 2. Note that in the following description, the portion where the stitches 23a are smaller than those in the loosely knitted portion 26 may be referred to as the "densely knitted portion 25."

[0081] The convex ridge portion 3 includes the terminal end 24a, the annular portion 28, and the knot 27, but does not include the stitches 23a. Therefore, the convex ridge portion 3 is a portion that does not include the stitches 23a, and where the density of the knitting yarn 21 in the molded product 1 is lower than in other portions (the dense knit portion 25). In other words, the convex ridge portion 3 is included in the low fiber density portion 2.

[0082] As described above, in the molded product 1 of this embodiment, the low fiber density portion 2 includes the convex portion 3 and the loosely knitted portion 26. In other words, in the molded product 1 of this embodiment, the low fiber density portion 2 includes both a portion where the stitches 23a are larger than the stitches 23a in other portions (slackly knitted portion 26) and a portion where there are no stitches 23a (convex portion 3). Note that the density of the knitting yarn 21 in the molded product 1 is in the order of lowest to highest, "convex portion 3 < loosely knitted portion 26 < densely knitted portion 25".

[0083] Next, the state of the molded article 1 after the resin material 10 has been melted will be described with reference to FIG. 1( b). As shown in FIG. 1( b), the molded article 1 has a portion (openly knitted portion 26) with larger stitches than the densely knitted portion 25 (other portions), and is configured so that the terminal end 24a is located in the openly knitted portion 26 after the resin material 10 has been melted. Therefore, in the molded article 1, the terminal end 24a, which was located in the convex portion 3 (low-fiber-density portion 2) before the resin material 10 was melted, is located in the openly knitted portion 26 after the resin material 10 has been melted. This makes it easier to distinguish the densely knitted portion 25 from the terminal end 24a and the openly knitted portion 26 after the resin material 10 has been melted, based on the difference in the size of the stitches 23a.

[0084] [Manufacturing Method of Molded Article of First Embodiment] Next, a description will be given of a manufacturing method of the molded article 1. The molded article 1 of this embodiment is molded by setting the knitted fabric substrate 22 in a mold and then injecting the resin material 10 into the mold.

[0085] 2 shows each step for manufacturing the molded product 1. In this embodiment, an example will be described in which the molded product 1 is molded by the RTM method. As shown in FIG. 2, the method for manufacturing the molded product 1 includes at least a base material forming step S100, a setting step S101, and a molding step S102. The steps included in the method for manufacturing the molded product 1 are performed in the order of the base material forming step S100, the setting step S101, and the molding step S102.

[0086] The base material forming step S100 is a step of knitting the knitting yarn 21 using a knitting machine (not shown) to form the knitted fabric base material 22. Specifically, in the base material forming step S100, the knitting yarn 21 is formed into a loop using the knitting machine, and the knitting yarn 21 is passed through the looped portion to sequentially form looped portions (stitches 23a). In this way, the knitted fabric base material 22 is formed with the stitches 23a formed continuously.

[0087] The setting step S101 is a step of setting the knitted fabric substrate 22 in a mold (not shown). The mold includes an upper mold and a lower mold, and the knitted fabric substrate 22 is set in the lower mold with the upper mold and the lower mold spaced apart. After the knitted fabric substrate 22 is set in the lower mold, the mold is clamped. By clamping the mold, a gap (cavity) into which the resin material 10 is injected is formed.

[0088] In the molding step S102, resin material 10 is injected into the cavity. After resin material 10 is injected into the cavity, resin material 10 gradually hardens over time. After resin material 10 has hardened, the mold is opened and molded product 1 is removed from the mold.

[0089] [Material Recovery Method] Next, a method for recovering the knitting yarn 21 and the resin material 10 from the molded product 1 will be described. As shown in Fig. 3, the process for recovering the knitting yarn 21 and the resin material 10 from the molded product 1 includes at least a heating step S110, a separating step S111, a terminal end gripping step S112, and a winding step S113. The steps for recovering the material of the molded product 1 are performed in the order of the heating step S110, the separating step S111, the terminal end gripping step S112, and the winding step S113.

[0090] In the heating step S110, a treatment is performed to heat the molded product 1. More specifically, in the heating step S110, the resin material 10 contained in the molded product 1 is heated and melted. In the heating step S110, the resin material 10 of the molded product 1 melts, making it possible to separate the knitting yarn 21 and the resin material 10. Note that when a thermosetting resin is used as the resin material, a decomposition step can be adopted in which the thermosetting resin is decomposed by chemical decomposition using chemicals or superheated steam decomposition instead of the heating step.

[0091] In the separation step S111, a process is performed to separate the knitting yarn 21 from the resin material 10. Specifically, in the separation step S111, the knitting yarn 21 and the molten resin material 10 are separated by a centrifuge (not shown). After being separated, the knitting yarn 21 and the resin material 10 are each processed for reuse. The knitting yarn 21 is reused as a knitting yarn again after passing through an end holding step S112 and a winding step S113, which will be described below.

[0092] In the end gripping step S112, the end 24a of the knitting yarn 21 is gripped and set in a winding machine (not shown). As described above, in the molded product 1, the stitches 23a are larger in the low-fiber-density portion 2 including the end 24a compared to other portions. In other words, the stitches 23a are fine and the knitting yarn 21 is densely packed in other portions other than the periphery of the end 24a, but the stitches 23a are large and the knitting yarn 21 is sparse around the end 24a. Therefore, in the molded product 1, the end 24a of the knitting yarn 21 is easy to find and grip in the knitted fabric substrate 22 after separation from the resin material 10.

[0093] In the winding step S113, the stitches 23a of the knitted fabric substrate 22 are unraveled while the terminal end 24a is pulled, and the knitting yarn 21 is wound up. The knitting yarn 21 is recovered while maintaining its length. This allows for a wider range of uses for the recovered knitting yarn 21.

[0094] [First Modification] Next, a first modification of the molded article 1 according to the first embodiment will be described. When the fiber material of the molded article of the present invention is a knitted yarn, the molded article 30 may have the configuration shown in FIG. 4( a). Specifically, in the molded article 30 shown in FIG. 4( a), the low-fiber-density portion 32 is a flat portion that does not include any convex portions. In the molded article 30, the stitches 23a in the low-fiber-density portion 32 are larger than those in other portions. In the molded article 30, after the resin material 10 is melted, the end portion 24a is located in the portion where the stitches 23a are larger (the loose knit portion 26). With this configuration, in the molded article 30, after the resin material 10 is melted, it is possible to distinguish the stitches 23a of the dense knit portion 25 from the end portion 24a and the loose knit portion 26 where the end portion 24a is located.

[0095] [Second Modification] Next, a second modification of the molded article 1 according to the first embodiment will be described. When the fiber material of the molded article of the present invention is a knitting yarn, the configuration shown in FIG. 4(b) may be used. Specifically, in the molded article 40 shown in FIG. 4(b), the low-fiber-density portion 42 is a flat portion that does not include a convex portion. Furthermore, in the molded article 40, the knitted fabric substrate 22 is provided with a hole portion 43 without a stitch 23a, and the end portion 24a is disposed in the hole portion 43. In the molded article 40, the amount of knitting yarn 21 (annular portion 28, knot 27, end portion 24a) in the hole portion 43 is smaller than in other portions (knitted fabric portion 29 with stitches 23a). That is, in the molded article 40, the hole portion 43 forms a low-fiber-density portion 42 in which the density of the knitting yarn 21 in the molded article 40 is low.

[0096] The molded article 40 is configured so that the end portion 24a is located in the hole 43 after the resin material 10 is melted. With this configuration, the knitted fabric portion 29, the end portion 24a, and the hole 43 can be distinguished from each other after the resin material 10 is melted.

[0097] [Third Modification] Next, a third modification of the molded product 1 according to the first embodiment will be described. When the fiber material of the molded product of the present invention is a knitting yarn, the configuration shown in FIG. 4(c) may be adopted. Specifically, the molded product 50 shown in FIG. 4(c) has a convex portion 53 formed in an annular shape. In the molded product 50, the terminal end 24a of the knitting yarn 21 forms a one-sided knot with a knot 27 at the base of the annular portion 28, where the knitting yarn 21 is annular. In the molded product 50, a low-fiber density portion 52, where the density of the knitting yarn 21 in the molded product 50 is lower than in other portions, is provided, including a portion (open knit portion 26) where the stitches 23a are larger than in other portions, and a convex portion 53 in which the annular portion 28 is housed.

[0098] The molded product 50 is configured so that the end 24a is located in the portion (open knit portion 26) where the stitches 23a are large after the resin material 10 is melted. With this configuration, the molded product 30 can distinguish the stitches 23a of the dense knit portion 25 from the end 24a and the open knit portion 26 where the end 24a is located after the resin material 10 is melted.

[0099] [Fourth Modification] Next, a fourth modification of the molded article 1 according to the first embodiment will be described. When the fiber material of the molded article of the present invention is a knitting yarn, the configuration shown in FIG. 4(d) may be used. Specifically, the molded article 60 shown in FIG. 4(d) has a raised convex portion 63. In the molded article 60, the terminal end 24a of the knitting yarn 21 is knotted in a single knot, forming a circular portion 28 in which the knitting yarn 21 is looped, with a knot 27 at the base of the circular portion 28. The terminal end 24a is accommodated in the convex portion 63. In the molded article 60, the knitting yarn 21 (the circular portion 28, the knot 27, and the terminal end 24a) in the convex portion 63 is smaller than in other portions (the knitted fabric portion 29 with the stitches 23a). That is, in the molded article 60, the convex portion 63 forms a low-fiber density portion 62 in which the density of the knitting yarn 21 in the molded article 60 is low.

[0100] The molded product 60 is configured so that, after the resin material 10 is melted, the end portion 24a is exposed and positioned on the surface of the knitted fabric substrate 22. With this configuration, the knitted fabric portion 29 and the end portion 24a can be distinguished from each other after the resin material 10 is melted.

[0101] Second Embodiment Next, the configuration of a molded product 70 according to a second embodiment of the present invention will be described with reference to Fig. 5. Fig. 5(a) is a cross-sectional view showing a main part of the molded product 70. Fig. 5(b) is a plan view showing a main part of the molded product 70.

[0102] The molded product 70 is a molded product of a fiber-reinforced composite material including a fiber material 20 serving as a reinforcing material and a resin material 10 serving as a matrix material. In the molded product 70 of this embodiment, a thermoplastic resin that can be melted by heating is used as the resin material 10. In addition, in the molded product 70 of this embodiment, the fiber material 20 is a tape material 73 in which carbon fiber is formed into a sheet shape. The molded product 70 is formed by laminating a tape-shaped prepreg in which the tape material 73 is impregnated with the resin material 10. In addition, as shown in FIGS. 5( a) and 5(b), the molded product 70 has a low-fiber-density portion 72.

[0103] 5A, the terminal end 74a of the tape material 73 is covered with the film material 75. The amount of resin material 10 near the terminal end 74a of the tape material 73 is greater than in other parts, forming a convex shape (convex portion 72a). Therefore, in the molded product 70, the proportion (density) of the tape material 73 in the vicinity of the terminal end 74a of the tape material 73 (low-fiber-density portion 72) is lower than in other parts (density of the tape material 73: low-fiber-density portion < other parts).

[0104] 5(b), in the molding 70, the tape material 73 is layered at approximately regular intervals and in paths that form approximately the same angle in the portions other than the terminal end portion 74a, whereas the terminal end portion 74a has a path that curves differently from the paths formed by the other tape materials 73. Therefore, in the molding 70, after the resin material 10 is melted, the tape material 73 in the other portions is arranged at approximately regular intervals and angles, whereas the tape material 73 in the terminal end portion 74a forms a different angle. With this configuration, in the molding 70, after the resin material 10 is melted, it is possible to distinguish the portion where the terminal end portion 74a is located (the portion that was the convex portion 72a) from the other portions.

[0105] REFERENCE SIGNS LIST 1 Molded product 2 Low fiber density portion 3 Convex portion (low fiber density portion) 10 Resin material 20 Fiber material 21 Knitting yarn (fiber material) 22 Knitted fabric base material 23a Knit stitch 24a End portion (end portion) 25 Densely knitted portion (other portion) 26 Sparsely knitted portion (low fiber density portion) 27 Knot 28 Annular portion 30 Molded product 32 Low fiber density portion 40 Molded product 42 Low fiber density portion 43 Hole portion (low fiber density portion) 50 Molded product 52 Low fiber density portion 53 Convex portion (low fiber density portion) 60 Molded product 62 Low fiber density portion 63 Convex portion (low fiber density portion) 70 Molded product 72 Low fiber density portion 73 Tape material (fiber material) 74a End portion (end portion)

Claims

1. A molding of a fiber-reinforced composite material comprising: a resin material which serves as a base material and which can be melted or decomposed; and a fiber material which serves as a reinforcing material and is embedded in the resin material in a continuous state so as to form a shape corresponding to the resin material, wherein the molding has a low fiber density portion in which the density of the fiber material is lower than other portions of the molding, and the fiber material is embedded in the resin material such that at least one of the starting end and the ending end of the fiber material is located in the low fiber density portion, making the end located in the low fiber density portion identifiable after the resin material is melted or decomposed, and the shape formed by the fiber material can be released and recovered by removing the end located in the low fiber density portion after the resin material is melted or decomposed.

2. A molded product as described in claim 1, wherein the low fiber density portion includes a convex portion that forms a convex shape on the surface of the molded product, and the fiber material is configured such that the end portion of the fiber material is located in the convex portion that forms a convex shape on the surface of the molded product, making it possible to identify the end portion that was located in the low fiber density portion after the resin material is melted or decomposed, and making it possible to identify the position of the end portion that was located in the low fiber density portion before the resin material was melted or decomposed.

3. A molded product as described in claim 2, wherein the end of the fiber material is located in the convex portion that is convex, including a hook shape or a ring shape, on the surface of the molded product, so that the end that was located in the low fiber density portion after the resin material is melted or decomposed can be identified, and the position of the end that was located in the low fiber density portion before the resin material is melted or decomposed can be identified.

4. A molded product according to any one of claims 1 to 3, wherein the fiber material is a knitting yarn formed into a thread-like shape, the knitting yarn forms a knitted base material having continuous stitches in which the knitting yarn is looped, and the knitting yarn is embedded in the resin material so that the end portion is located in the low fiber density portion in which the density of the knitting yarn in the molded product is lower than the other portions, making it possible to identify the end portion located in the low fiber density portion after melting or decomposing the resin material, and making it possible to unravel and recover the knitted base material by removing the end portion located in the low fiber density portion after melting or decomposing the resin material.

5. A molding as described in claim 4, wherein the low fiber density portion includes a portion having larger stitches than the stitches of the other portions, and the knitting yarn is configured such that the end portion is located in the portion having larger stitches than the stitches of the other portions, thereby making it possible to identify the end portion that was located in the low fiber density portion after the resin material is melted or decomposed.

6. A molded product as described in claim 4 or 5, wherein the knitting yarn has an end portion where a knot is formed by tying the knitting yarn, the end portion being located in the low fiber density portion where the density of the knitting yarn is lower than the other portions of the molded product, so that the end portion located in the low fiber density portion can be identified after the resin material is melted or decomposed.

7. A molded product as described in claim 6, wherein the knitting yarn is configured such that a ring-shaped portion is formed in the low fiber density portion of the molded product where the density of the knitting yarn is lower than other portions, and the end portion is located at the base of the ring-shaped portion, forming a single knot with the knot, so that the end portion that was located in the low fiber density portion can be identified after the resin material is melted or decomposed.

8. A molded product according to any one of claims 4 to 7, wherein the knitting yarn is formed into a knitted base material having a continuous loop of stitches and a three-dimensional shape, and the end portion is located in the low fiber density portion in which the density of the knitting yarn is lower than other portions of the molded product, so that the end portion located in the low fiber density portion can be identified after the resin material is melted or decomposed.

Images