Molded article and method for manufacturing molded article

Abstract

This molded article (10) is made of a fiber-reinforced composite material and comprises a knitted fabric layer (12) including a meltable or decomposable resin material (11) and a knitted fabric base material (20) obtained by knitting knitting yarns (21). The molded article includes: a core material layer (13) including a core material (30) having a lower tensile strength than the knitted fabric layer (12); and two knitted fabric layers (12). The knitted fabric base material (20) is formed so as to follow the shape of the molded article (10) in a state in which the knitting yarn (21) in a continuous state is knitted and the continuity of the knitting yarn (21) is maintained. The core material layer (13) is disposed along at least a portion of each of the two knitted fabric layers (12) and between the two knitted fabric layers (12) so as to alleviate the load applied to the knitted fabric layers (12) when a load is applied to the molded article (10).

Description

Molded article, and method for manufacturing molded article

[0001] The present invention relates to a molded article made of a fiber-reinforced composite material and a method for manufacturing the molded article.

[0002] In recent years, from the perspective of environmental consideration, the demand for reusing used materials for various products has been increasing. In particular, for large parts such as ship hull parts, the amount of materials used is large, and the desire to reuse the materials is growing. By the way, in fiber-reinforced composite materials, woven fabrics are often used as reinforcing materials. However, in a fiber-reinforced composite material using a woven fabric as a reinforcing material, since the woven fabric is cut according to the shape of the part, even if the resin material is removed by melting or the like and the woven fabric is recovered, it is difficult to reuse the woven fabric as a reinforcing material for parts with different shapes. On the other hand, if a knitted fabric is adopted as the reinforcing material of the fiber-reinforced composite material, the knitted fabric can be formed seamlessly in a shape suitable for the part to be molded. Therefore, by untying the knitting yarn and re-knitting it into a knitting yarn for another type of part, it can be reused for a wide variety of parts.

[0003] For example, Patent Document 1 below discloses a fiber-reinforced composite material in which a reinforcing material is a knitted fabric base material and a thermoplastic resin is used as a resin material.

[0004] Japanese Unexamined Patent Application Publication No. 2021-133593

[0005] Here, for example, in the case of a fiber-reinforced composite component (e.g., interior part) where a knitted layer is formed on one side of the molded product and the knitted fabric is used as decoration, large loads are unlikely to be applied, and there is little concern about changes in the mechanical properties of the knitted yarn. On the other hand, in parts where strength is required, loads such as impacts on the molded product can be expected. Furthermore, when a load such as an impact is applied to the molded product, it can potentially be applied to the knitted yarn contained within the molded product. For example, if the knitted base material contained in a molded product is made up of a single knitted yarn and is hardened with a resin material, when an external load (such as something hitting it) is applied to the molded product, that load may be concentrated on a part of the knitted yarn contained in the knitted layer. In addition, if the knitted yarn is repeatedly subjected to loads, its mechanical properties will change, and when the resin material is removed from the molded product by dissolving it or other means and the knitted yarn is recovered, the knitted yarn may break, reducing the recovery rate of the knitted yarn, or it may become necessary to remove knitted yarn with altered mechanical properties, resulting in a reduced recovery rate of a single knitted yarn and making it difficult to reuse.

[0006] Furthermore, in the case of a molded fiber-reinforced composite material in which tape materials such as carbon fiber are laminated, if a load is applied to one location on the molded product, the load is concentrated on one location for each tape material, so the range over which the mechanical properties of the tape material change is small (e.g., one location). In contrast, since knitted fabric base materials are constructed so that each knitted thread intersects and entangles with the others, even if a load is applied to one location, the load will be distributed to multiple locations where the knitted threads intersect, and the mechanical properties may change at multiple locations. In other words, in a molded product using tape material as a reinforcement, if a load occurs at one location, the range over which the mechanical properties of the tape material change is limited (e.g., one location), whereas in a molded product using knitted fabric base materials as a reinforcement, if a load occurs at one location, the parts of the knitted threads that change mechanical properties may extend to multiple locations.

[0007] Therefore, the present invention aims to provide a molded fiber-reinforced composite material that can increase strength and suppress changes in the mechanical properties of the knitted yarn, thereby facilitating the recovery and reuse of the knitted yarn, and a method for manufacturing the molded material.

[0008] The inventors of this application investigated means to improve the strength of a molded product while suppressing changes in the mechanical properties of the knitted yarn. The inventors of this application first investigated how to improve the strength of a molded product. For example, if the molded product is a part that is not subjected to heavy loads, such as an interior part of a vehicle, then the molded product does not need to be very strong. A molded product used as a part where strength is not required may include, for example, a knitted fabric layer impregnated with a resin material on a knitted fabric base. This knitted fabric layer may be used, for example, for decoration of the molded product.

[0009] On the other hand, exterior parts such as the hull of a ship or the cowl and fenders of a motorcycle require greater strength than interior parts. It is desirable for molded parts used in applications requiring high strength to contain two knitted layers. For example, in parts requiring high strength, it is desirable that both the area near the surface and the area near the back surface have high strength in the thickness direction of the part. When a molded part contains two knitted layers, for example, one knitted layer can reinforce the area near the surface, and the other knitted layer can reinforce the area near the back surface. Therefore, it is desirable for molded parts used in applications requiring high strength to contain two knitted layers.

[0010] Next, the inventors of the present invention considered means to suppress changes in the mechanical performance of the knitted yarn. Specifically, the inventors considered suppressing changes in the mechanical performance of the knitted yarn by providing two knitted layers and configuring a core material layer between these knitted layers. Here, if a highly rigid material is used as the core material, the strength of the molded product itself can be increased, but when a load is applied to the molded product, the load cannot be absorbed by the core material layer and becomes a load on the knitted layer, which may result in a load being placed on the knitted yarn. Therefore, the inventors of the present invention considered a configuration that increases the strength of the molded product by providing two knitted layers, while also buffering the load on the core material layer when a load is applied to the molded product.

[0011] Furthermore, in the case of a molded product with a layer structure consisting of a knitted fabric layer, a core material layer with lower tensile strength than the knitted fabric layer, and a resin material layer with lower tensile strength than the knitted fabric layer, the resin material layer is more likely to absorb energy. On the other hand, in the case of a molded product with a layer structure consisting of a knitted fabric layer, a core material layer, and another knitted fabric layer, the core material layer, which has relatively lower tensile strength, can absorb energy and buffer the load. Thus, in the case of a molded product with a layer structure consisting of a knitted fabric layer, a core material layer, and another knitted fabric layer (a structure in which the core material layer is sandwiched between knitted fabric layers), the load on the knitted fabric layer can be buffered.

[0012] As described above, the inventors of this application have found that by constructing two knitted layers and placing a core material made of a material with lower rigidity than the knitted layers (a material with lower tensile strength) between these knitted layers and along the knitted layers to a certain extent, the load on the knitted yarn can be suppressed. Specifically, by placing a core material made of a material with lower rigidity than the knitted layers between two knitted layers to a certain extent (at least along a part of them) along these knitted layers, the load on the knitted layers can be mitigated by the core material layer, thereby suppressing changes in the mechanical performance of the knitted yarn. As a result, the two conflicting problems of improving the strength of the molded product and suppressing the load on the knitted yarn can be solved simultaneously.

[0013] (1) Based on the above findings, the molded article of the present invention is a molded article of a fiber-reinforced composite material comprising a meltable or decomposable resin material and a knitted layer comprising a knitted base material in which knitted yarn is knitted, the molded article comprising a core material layer comprising a core material having a lower tensile strength than the knitted layer, and two knitted layers, wherein the knitted base material is formed to conform to the shape of the molded article in which the knitted yarn is knitted in a continuous state and the continuity of the knitted yarn is maintained, and the core material layer is positioned along at least a portion of each of the two knitted layers and between the two knitted layers to mitigate the load applied to the knitted layer when a load is applied to the molded article.

[0014] In the molded product described in (1) above, two knitted layers are provided to increase the strength of the molded product, and a core material layer containing a core material with a lower tensile strength than the knitted layers is placed between these knitted layers along the knitted layers. As a result, the core material layer acts as a buffer that absorbs and mitigates external loads on the molded product, thereby reducing the load on the knitted layers. Therefore, the molded product described in (1) above can meet the requirement for increased strength while also mitigating the load on the knitted yarn contained in the knitted layers and suppressing changes in the mechanical properties of the knitted yarn. Consequently, when the resin material is removed by dissolution or the like to recover the knitted yarn in the molded product described in (1), situations such as the knitted yarn breaking or the need to remove damaged knitted yarn are suppressed, and the knitted yarn can be recovered while maintaining its length. As a result, the molded product described in (1) above can increase strength and suppress changes in the mechanical properties of the knitted yarn, making it easier to recover and reuse the knitted yarn.

[0015] (2) In the molded article of the present invention described in (1) above, the knitted layer is formed by impregnating the knitted base material with the resin material, and it is preferable that the knitted base material is included throughout the entire thickness of the molded article.

[0016] In the molded product described in (2) above, since the knitted layer is a layer in which resin material is impregnated into the knitted base material, the presence of a layer of resin material only (resin material layer) between the knitted base material and the core material layer is suppressed, and the external load of the molded product can be absorbed more effectively by the core material layer, thereby reducing the load on the knitted layer. In addition, in the molded product described in (2) above, since the knitted base material is present throughout the entire thickness of the knitted layer, the strength of the knitted layer can be improved. As a result, the molded product described in (2) above can be made stronger and the change in the mechanical performance of the knitted yarn can be further suppressed, making it easier to recover and reuse the knitted yarn.

[0017] (3) The molded article of the present invention, in the molded article described in (1) or (2) above, wherein the core material is a porous body containing a plurality of pores, and at least some of the pores are independent of the other pores, and the core material layer contains air by having portions of at least some of the pores in the porous body that are not impregnated with the resin material, so as to mitigate the load applied to the knitted layer when a load is applied to the molded article by the deformation of the pores, and is arranged along at least a portion of each of the two knitted layers and between the two knitted layers.

[0018] In the molded product described in (3) above, two knitted layers are provided in the molded product of the fiber-reinforced composite material to increase the strength of the molded product. Furthermore, a core material layer made of a porous body containing pores is placed between these knitted layers along the knitted layers. As a result, the pores in the core material layer deform, acting as a buffer and reducing the load on the knitted layers. Therefore, the molded product described in (3) above can meet the requirement for increased strength of the molded product while also mitigating the load on the knitted yarn contained in the knitted layers and suppressing changes in the mechanical properties of the knitted yarn. Consequently, when the resin material is removed by dissolution or the like to recover the knitted yarn, the molded product described in (3) above can prevent situations such as the knitted yarn breaking or the need to remove damaged knitted yarn, and the knitted yarn can be recovered while maintaining its length. As a result, the molded product described in (3) above can increase strength and suppress changes in the mechanical properties of the knitted yarn, making it easier to recover and reuse the knitted yarn.

[0019] (4) The molded article of the present invention is preferably the molded article described in any of (1) to (3) above, wherein one knitted base material is arranged to surround at least a part of the core material, and the core material layer is arranged between two knitted layers.

[0020] In the molded product described in (4) above, since two knitted layers are formed from a single knitted base material, when the resin material is removed by dissolution or the like, the knitted yarn can be recovered in a longer state (as a single strand). As a result, the molded product described in (4) above has increased strength, suppresses changes in the mechanical properties of the knitted yarn, allows for the recovery of the knitted yarn as a single strand, and makes it easier to reuse the knitted yarn.

[0021] (5) The molded article of the present invention may be a molded article according to any of (1) to (4) above, and may include a surface layer that constitutes the surface of the molded article and protects the knitted layer.

[0022] In the molded product described in (5) above, a layer separate from the knitted layer (a surface layer) exists on the surface of the knitted layer, thereby suppressing and mitigating the direct transmission of external loads to the knitted layer. Furthermore, the molded product described in (5) above can suppress surface damage caused by scratching, changes in the mechanical properties of the knitted yarn due to water or ultraviolet rays, etc. As a result, the molded product described in (5) above can be made stronger and further suppress changes in the mechanical properties of the knitted yarn, making it easier to recover and reuse the knitted yarn.

[0023] The inventors of the present invention investigated how to further increase the strength of molded fiber-reinforced composite materials using a knitted fabric base material as a reinforcing material, and found that the strength of the molded product can be further improved by molding the knitted fabric base material under tension. However, molding the knitted fabric base material under tension tends to cause localized stress on the knitted yarn. The inventors of the present invention investigated a configuration that allows molding the knitted fabric base material under tension while also preventing stress from concentrating on the knitted yarn. As a result, they found that by forming a core material layer along the portion of the knitted fabric base material that is molded under tension, the core material layer can absorb the stress on the knitted fabric layer and alleviate the stress on the knitted yarn.

[0024] (6) The molded article of the present invention is a molded article according to any one of (1) to (5) above, wherein the knitted layer includes a tension-reinforced portion when tension is applied to the knitted base material, and the core material layer is preferably arranged along the tension-reinforced portion and between the two knitted layers so as to alleviate the load applied to the tension-reinforced portion when a load is applied to the molded article.

[0025] According to the molded product described in (6) above, the core material layer is positioned along the portion of the knitted base material that is molded under tension (the tension-reinforced portion), so that the load on the tension-reinforced portion can be alleviated by the core material layer. As a result, the molded product described in (6) above can be made stronger and the changes in the mechanical properties of the knitted yarn can be suppressed, making it easier to recover and reuse the knitted yarn.

[0026] (7) The molded article of the present invention is the molded article described in (6) above, wherein the molded article includes a plurality of holes that open on at least one surface and penetrate the knitted stitches, and the knitted layer may have the tension-reinforced portion located inside the positions where the plurality of holes are formed.

[0027] According to the molded product described in (7) above, the knitted base material is molded under tension, and the core material layer is arranged along the portion formed inside the location where multiple holes are formed (tensile reinforcement portion). As a result, the load on the tensile reinforcement portion can be alleviated by the core material layer. Consequently, the molded product described in (7) above can be made stronger, and changes in the mechanical properties of the knitted yarn can be suppressed, making it easier to recover and reuse the knitted yarn.

[0028] (8) In the molded product of the present invention as described in (7) above, the knitted base material is preferably thicker in the portion including the edge of the hole than in other portions.

[0029] When tension is applied to the knitted base material by passing a locking member or the like through the hole, the load tends to concentrate in that area. In the molded product described in (8) above, the part of the knitted base material including the hole has increased thickness, so the area around the hole can be reinforced. As a result, the molded product described in (8) above can be made even stronger, and changes in the mechanical properties of the knitting yarn can be suppressed, making it easier to recover and reuse the knitting yarn.

[0030] (9) A method for manufacturing a molded article of the present invention comprises a setting step of setting a knitted base material and a core material, which are knitted yarns in a continuous state, into a mold, and a molding step of forming a molded article by curing a molten or decomposable resin material in the mold after the setting step, wherein in the molding step, the resin material is cured with the core material positioned along the knitted base material under tension, forming a core material layer including the core material between two knitted layers including the resin material and the knitted base material, and in the setting step, the knitted base material and the core material are set into the mold with tension applied to at least a part of the knitted base material and with the core material layer formed between the two knitted layers.

[0031] According to the manufacturing method of the molded product described in (9) above, the strength of the knitted layer can be improved by applying tension to the knitted base material during molding. Furthermore, according to the manufacturing method of the molded product described in (9) above, by providing two knitted layers to increase the strength of the molded product, and by arranging a core material layer containing a core material with a lower tensile strength than the knitted layers between these knitted layers along the knitted layers, the core material layer acts as a buffer that absorbs and mitigates the load on the molded product, thereby enabling the production of a molded product that can reduce the load on the knitted layers. Therefore, the molded product produced by the manufacturing method of the molded product described in (9) above can meet the requirement for improved strength while mitigating the load on the knitted yarn contained in the knitted layer and suppressing changes in the mechanical performance of the knitted yarn. Accordingly, the manufacturing method of the molded product described in (9) above can produce a molded product in which, when the resin material is removed by dissolution or the like to recover the knitted yarn, situations such as the knitted yarn breaking or the need to remove damaged knitted yarn are suppressed, and the knitted yarn can be recovered while maintaining its length. As a result, the method for manufacturing the molded product described in (9) above can produce a molded product that has increased strength and suppresses changes in the mechanical properties of the braided yarn, making it easier to recover and reuse the braided yarn.

[0032] (10) The method for manufacturing a molded product of the present invention is the method for manufacturing a molded product described in (9) above, wherein in the setting step, the knitted base material is set in the mold in advance by setting it in the core material so that tension is applied along the shape of the core material.

[0033] According to the method for manufacturing molded products described in (10) above, by setting the knitted base material on the core material in advance before setting it on the mold, misalignment of the knitted base material relative to the core material is suppressed, and tension can be easily applied to the desired position. As a result, the method for manufacturing molded products described in (10) above can produce molded products that have increased strength in the desired area and suppress changes in the mechanical performance of the knitted yarn, making it easier to recover and reuse the knitted yarn.

[0034] (11) The method for manufacturing a molded product of the present invention is the method for manufacturing a molded product described in (9) above, wherein in the setting step, the knitted base material is set against the mold while tension is applied.

[0035] According to the method for manufacturing molded products described in (11) above, applying tension when setting the knitted base material in the mold makes it easier to apply tension to the desired position. As a result, the method for manufacturing molded products described in (11) above makes it possible to produce molded products that have increased strength in the desired area and suppress changes in the mechanical properties of the knitted yarn, making it easier to recover and reuse the knitted yarn.

[0036] (12) The method for manufacturing a molded product of the present invention is the method for manufacturing a molded product described in (11) above, wherein in the setting step, the knitted base material is set against the mold while tension is applied by passing the knitted stitches through a plurality of locking members positioned in the mold.

[0037] According to the manufacturing method of the molded product described in (12) above, when setting the knitted base material in the mold, the knit stitches are passed through locking members such as pins and hooks, and tension is applied while setting, which makes it easier to apply tension to the desired position while suppressing misalignment of the knitted base material relative to the mold. For example, by providing locking members at positions corresponding to the ends and bends of the molded product, even molded products with complex shapes can have tension applied to the knitted base material while suppressing misalignment. As a result, the manufacturing method of the molded product described in (12) above can produce molded products that have increased strength in desired areas and suppress changes in the mechanical properties of the knitted yarn, making it easier to recover and reuse the knitted yarn.

[0038] [About the molded product] The molded product of the present invention comprises multiple layers. Specifically, the molded product includes a knitted fabric layer and a core material layer. The molded product has a configuration in which the core material layer is arranged between two knitted fabric layers. That is, the molded product has a configuration in which the knitted fabric layer and the core material layer are laminated in the thickness direction of the molded product. In this specification, one of the two knitted fabric layers may be referred to as the "first knitted fabric layer" and the other as the "second knitted fabric layer." The core material layer is arranged between the first knitted fabric layer and the second knitted fabric layer.

[0039] The "thickness direction" is the direction that intersects (for example, perpendicular to) the surface of the molded product. For example, if the two surfaces of a molded product formed corresponding to the front and back of a knitted base material are designated as the first surface and the second surface, the thickness direction includes the first direction from the second surface toward the first surface and the second direction from the first surface toward the second surface.

[0040] "Meltable or decomposable resin materials" include, 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 are an example of resin materials that can be melted by heating. Also, for example, thermosetting resins are an example of resin materials that can be decomposed by chemical decomposition using chemicals or by superheated steam decomposition. The resin material should, for example, be recoverable by melting or decomposing. 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.

[0041] "A core material with lower tensile strength than the knitted layer" means that the core material has lower tensile strength than the knitted layer, which is formed by impregnating the knitted base material with resin and allowing it to harden. The core material should ideally have a small weight per unit volume. For example, the core material should ideally have a smaller weight per unit volume (lighter) than the knitted layer. The core material should also ideally be a thick material. For example, the core material can be made of a material that is thicker than the knitted layer. The core material can, for example, be a porous material.

[0042] "A porous body" is a material that contains a plurality of pores, and at least some of the pores are independent of other pores. The porous body contains air, for example, because pores are formed. Examples of the porous body include foams made from resins and woods such as balsa wood.

[0043] The core material may be, for example, formed according to the shape of the molded article. The core material may be, for example, in a plate shape. The molded article may include, for example, a plurality of core materials.

[0044] "A core material layer" contains a core material. The core material layer may be, for example, configured such that a resin material is impregnated into a part of the core material. The core material layer contains air, for example. For example, the core material layer may be a layer in which a resin material is impregnated on the surface of the core material so that the air contained in the core material remains.

[0045] "The core material layer is arranged along at least a part of each of the two knitted fabric layers and between the two knitted fabric layers so as to relieve the load applied to the knitted fabric layer when a load is applied to the molded article" means, for example, that the core material layer disperses and relieves the energy to the knitted fabric layer by deformation of the structure of the core material. For example, the core material layer is arranged at a position where it relieves the load on the knitted fabric layer. The core material layer can be configured, for example, in a shape that matches the shape of the knitted fabric layer in at least a part of the molded article.

[0046] For example, the core material layer may be provided within a certain range with respect to the range where the knitted fabric layer is provided. For example, the core material layer may be provided so as to overlap the entire area or substantially the entire area of the knitted fabric layer when viewed in the thickness direction. For example, the core material layer may be configured such that the overlapping area with the knitted fabric layer is larger than the area of the non-overlapping part when viewed in the thickness direction. For example, the core material layer may be provided so as to overlap a part of the knitted fabric layer when viewed in the thickness direction.

[0047] For example, the core material layer may be provided so as to be sandwiched between the first knitted fabric layer and the second knitted fabric layer in a cross-sectional view (view in a direction orthogonal to the thickness direction) of the molded article (sandwich structure). For example, the core material layer may be provided at a position capable of absorbing the loads of the first knitted fabric layer and the second knitted fabric layer. For example, the core material layer may be provided such that at least a part thereof is in contact with the first knitted fabric layer and / or the second knitted fabric layer.

[0048] For example, another layer may be provided between the core material layer and the knitted fabric layer. For example, another layer smaller than the thickness of the knitted fabric layer may be provided between the core material layer and the knitted fabric layer. For example, another layer may be provided between the core material layer and the first knitted fabric layer. For example, another layer may be provided between the core material layer and the second knitted fabric layer. The core material layer can be configured, for example, to have a greater thickness than the knitted fabric layer. The separation distance between the core material layer and the knitted fabric layer can be configured, for example, to be smaller than the thickness of the knitted fabric layer.

[0049] The position of the first knitted fabric layer may be provided, for example, at a position closer to the first surface than the middle in the thickness direction of the molded article in a cross-sectional view. The position of the second knitted fabric layer may be provided, for example, at a position closer to the second surface than the middle in the thickness direction of the molded article in a cross-sectional view. The layer from the core material layer to the first surface may include, for example, the first knitted fabric layer and other layers (for example, a gel coat layer), and may be 1 to 3 layers. The layer from the core material layer to the second surface may include, for example, the second knitted fabric layer, and may be 1 to 2 layers.

[0050] The first knitted fabric layer and the second knitted fabric layer may be connected, for example. For example, a single tubular or bag-shaped knitted fabric base material may be arranged so as to surround the core material. That is, the molded article may be configured such that the first knitted fabric layer and the second knitted fabric layer are connected so as to cover the ends of the core material layer. For example, the knitted fabric layer may be a connecting portion between the first knitted fabric layer and the second knitted fabric layer, and may include a portion (connecting portion) that covers the ends of the core material layer. The molded article may be configured such that the core material layer is sandwiched between the first knitted fabric layer and the second knitted fabric layer at portions other than the connecting portion.

[0051] A "tubular knitted base material" is, for example, a knitted base material formed in an annular shape. A tubular knitted base material is, for example, a knitted base material with openings formed at both ends. A tubular knitted base material is, for example, a knitted base material having two openings. A "bag-shaped knitted base material" is, for example, a knitted base material that is closed on three sides and has one opening.

[0052] The core material layer may be configured to be in contact with the knitted fabric layer, for example. Alternatively, another layer may be formed between the core material layer and the knitted fabric layer. For example, a unidirectional fiber-reinforced material such as UD tape (Uni-directional Tape) may be placed between the core material layer and the knitted fabric layer.

[0053] "Knitted yarn" refers to, for example, thread-like materials (including cord-like materials) that constitute the stitches of a knitted fabric base material. Knitted yarn includes, for example, at least one fiber material. Knitted yarn is formed into a thread-like shape by twisting together multiple fiber materials. Knitted yarn may contain, for example, one type of fiber material or multiple types of fiber materials. The thickness of the knitted yarn can be appropriately selected depending on, for example, the size and thickness of the molded product and the knitting machine used. In this specification, anything that can be knitted using a knitting machine is referred to as "knitted yarn" regardless of its thickness. That is, in this specification, "knitted yarn" includes both materials of a thickness generally referred to as "thread" and materials of a thickness generally referred to as "cord". Knitted yarn can be any material that can be used as a reinforcing material to strengthen a resin material. For example, various types of fiber materials can be selected to make up the knitted yarn, such as natural fibers, carbon fibers, and amilad fibers.

[0054] "Continuous state" means, for example, that the braided yarn is continuous from the beginning to the end. Furthermore, "continuous braided yarn" does not depend on whether it is a single, seamless braided yarn or whether it has a section where multiple braided yarns are connected (a joint). In other words, "continuous braided yarn" includes cases where the braided yarn has a joint in the middle. The braided yarn simply needs to be constructed so that it can be handled as a single strand. Also, it does not matter whether the braided yarn is a single strand or a bundle of multiple strands.

[0055] A "knitted base material" is, for example, a material in which knitting yarn forms continuous loops. More specifically, a knitted base material is, for example, a material in which knitting yarn is formed into continuous loops, and then more knitting yarn is passed through these loops to form more loops, so that the continuous loops (stitches) of knitting yarn form a knitted fabric. A knitted base material can be formed, for example, using a knitting machine.

[0056] The knitted base material may include, for example, reinforcing materials that do not constitute the stitches. For example, the knitted base material may include reinforcing materials other than knitting yarn. For example, the knitted base material may consist only of knitting yarn, or it may include knitting yarn and other yarn materials (e.g., bias yarn, inlay yarn, etc.).

[0057] The knitted base material included in the molded product may be, for example, a single sheet. Alternatively, there may be, for example, multiple knitted base materials. The knitted base material may be, for example, a single flat sheet, or a single knitted base material may be knitted into a three-dimensional shape (three-dimensional knitted fabric). For example, the knitted base material may be formed in a tubular shape. For example, the knitted base material may be formed in a bag shape.

[0058] "The knitted base material is formed to conform to the shape of the molded product" means, for example, that the knitted base material contained in one knitted layer is knitted into a shape that forms the shape (skeleton) of the molded product. "The knitted base material is formed to conform to the shape of the molded product" means, for example, that the knitted base material is located on most of the molded product. "The knitted base material is formed to conform to the shape of the molded product" means, for example, that the molded product is constructed such that the knitted layer, in which the knitted base material is impregnated with resin, forms the substantial outer shape of the molded product. "The knitted base material is formed to conform to the shape of the molded product" means, for example, that the knitted base material is embedded in the resin material throughout the entire area of ​​the molded product. "The knitted base material is formed to conform to the shape of the molded product" means, for example, that the knitted layer is provided over an area of ​​more than half of the surface area of ​​the molded product. "The knitted base material is formed to conform to the shape of the molded product" means, for example, that the portion of the molded product with the knitted layer is larger than the portion without the knitted layer. The knitted base material contained in one knitted layer may be, for example, a single three-dimensional knitted fabric. This helps to suppress the occurrence of steps or unevenness in the molded product due to seams in the knitted base material.

[0059] The "knitted layer" includes a resin material and a knitted fabric base material. The knitted layer is, for example, a layer formed by impregnating a knitted fabric base material with a resin material and allowing the resin material to harden. The knitted layer is, for example, a single layer containing the knitted fabric base material throughout its entire thickness. "Single layer" means, for example, that the knitted layer does not include a resin material layer in which only the resin material has hardened. The knitted layer contains the knitted fabric base material throughout its entirety.

[0060] The knitted layer may include, for example, a tension-reinforced section as described later. The knitted layer may include, for example, a standard section as described later. The knitted layer may include, for example, both a standard section and a tension-reinforced section as described later.

[0061] The "standard section" is the portion of the knitted fabric layer in which the resin material has hardened while no tension is applied to the knitted fabric base material. The standard section includes, for example, the standard stitch section, which will be described later. For example, the standard section is the portion of the knitted fabric layer in which the resin material has impregnated the standard stitch section and hardened.

[0062] The "tensile reinforced section" is the part of the knitted fabric layer in which the resin material has hardened while tension is applied to the knitted fabric base material. The tensile reinforced section includes, for example, the reinforced knitted section described later. For example, the tensile reinforced section is the part of the knitted fabric layer in which the resin material has impregnated the reinforced knitted section and hardened.

[0063] The knitted fabric base material will be described in more detail below. In this specification, the direction in which the yarn is supplied will be referred to as the "course direction," and the direction intersecting the course direction will be referred to as the "wale direction." Since the knitted fabric base material is constructed by knitting yarn, it is elastic. Therefore, when tension is applied to the knitted fabric base material, the fabric stretches in the direction of the tension, and the knitted stitches deform. For example, when no tension is applied to the knitted fabric base material, the fabric has portions where the knitted stitches are formed in a way that the yarn is curved (standard knitted portions). Also, for example, when tension is applied to the knitted fabric base material, portions where the knitted stitches are formed in a way that bends at the points where the yarns intersect (reinforced knitted portions).

[0064] The "standard knitted area" is the part of the knitted fabric base material that is not under tension. The standard knitted area is, for example, the part of the knitted fabric base material in which stitches are formed that form a meandering path for the knitting yarn. The standard knitted area is, for example, the part of the knitted fabric base material in which stitches are formed that form a curved shape for the knitting yarn.

[0065] A "reinforced knitted section" is a part of the knitted fabric base material under tension. A reinforced knitted section is, for example, a part of the knitted fabric base material in which stitches are formed that form a bent path where the knitting yarns intersect with each other. A reinforced knitted section is, for example, a part of the knitted fabric base material in which stitches are formed that form a rectangle. In a reinforced knitted section, for example, the aspect ratio of a single stitch differs from that of a standard knitted section. For example, when tension is applied to the knitted fabric base material in the wale direction (longitudinal direction), the stitches in the reinforced knitted section become larger in the wale direction than the stitches in the standard knitted section. Also, for example, when tension is applied to the knitted fabric base material in the course direction (lateral direction), the stitches in the reinforced knitted section become larger in the course direction than the stitches in the standard knitted section.

[0066] The "surface layer" is a layer that constitutes the surface of a molded product. The surface layer is, for example, a layer made of a different material from the resin material that constitutes the knitted fabric layer. The surface layer is, for example, a layer on which a coating agent has hardened. For example, the surface layer may be a layer on which a gel coat has hardened (a gel coat layer).

[0067] "A hole formed to open on at least one surface and penetrate the stitches" refers to a through-hole in a molded product formed to penetrate the stitches of a knitted base material. The hole may remain in the molded product as a through-hole, for example. The hole may be closed by other components, for example. For example, the hole may be closed by the presence of a locking member such as a pin or hook. For example, the hole may be closed by filling it with a material such as resin. Components present inside the hole (filler or locking member) do not constitute the molded product.

[0068] "The tensile reinforcement section is located inside the position where multiple holes are formed" means, for example, that the tensile reinforcement section is located within a region enclosed by a polygon with the positions where multiple holes are provided as vertices, when viewing the molded product in the thickness direction.

[0069] The molded product can be any part of a vehicle. For example, it can be applied to various things such as ship hull parts, blades, drone parts, and vehicle parts (e.g., motorcycle parts). Also, for example, the molded product can be the product itself (finished product). Examples of ship hull parts include the hull and deck. Examples of motorcycle parts include the cowl, cover, and fender.

[0070] The present invention allows for the selection of various methods for manufacturing molded products, such as setting a reinforcing material (e.g., a knitted fabric base material) that has not been impregnated with resin into a mold and injecting the resin material. One example of a method for setting a reinforcing material into a mold and injecting the resin material is the RTM (Resin Transfer Molding) method. The RTM method involves setting a reinforcing material into a mold, closing the mold which includes an upper mold and a lower mold, injecting the resin material into the cavity in the mold, impregnating the reinforcing material with the resin material within the mold, and allowing it to harden to form a molded product. The upper mold and lower mold include a film back. In other words, the RTM method includes a method of placing the reinforcing material between the upper or lower mold and the film back and impregnating it with resin material.

[0071] Furthermore, the method for manufacturing the molded product of the present invention may also be used to mold the product using a prepreg in which a resin material is coated onto knitted yarn. For example, a knitted base material may be constructed using a prepreg in which a resin material is coated onto knitted yarn, and the molded product may be formed by heating the prepreg.

[0072] Various methods can be selected for applying tension to the knitted base material during the setting process. For example, tension may be applied to the knitted base material by placing a core material inside a tubular or bag-shaped knitted base material. For example, tension may be applied to the knitted base material by creating irregularities at the ends of the core material and hooking the stitches of the knitted base material onto these irregularities to set the knitted base material on the core material. For example, tension may be applied to the knitted base material by fixing it to a mold with locking members such as hooks or pins while pulling the knitted base material. For example, tension may be applied to the knitted base material by pressing it against the mold and / or core material. For example, tension may be applied to the knitted base material by deforming it to conform to the mold and / or core material by vacuum drawing.

[0073] When two knitted base materials are set in a mold, the knitted base material setting process may include a first knitted base material setting process for setting the first knitted base material, and a second knitted base material setting process for setting the second knitted base material.

[0074] Furthermore, the method for applying tension to the knitted base material in the first knitted base material setting process and the method for applying tension to the knitted base material in the second knitted base material setting process may be the same or different. For example, in both the first and second knitted base material setting processes, tension may be applied to the knitted base material by inserting the stitches through the locking member. For example, in both the first and second knitted base material setting processes, tension may be applied to the knitted base material by pressing it against a mold or core material, or tension may be applied to the knitted base material by vacuum drawing. For example, in one of the first and second knitted base material setting processes, tension may be applied to the knitted base material by inserting the stitches through the locking member and setting it in the mold, while in the other, tension may be applied to the knitted base material by pressing it against a mold or core material, or tension may be applied to the knitted base material by vacuum drawing.

[0075] The setting process may include steps other than the process of setting the knitted base material and the process of setting the core material. For example, the setting process may include any of the following: a coating agent application process for applying a coating agent that constitutes the surface layer to the mold (for example, a gel coat application process for applying gel coat to the mold), a mold clamping process, a film bag setting process for setting the film bag that constitutes the mold, and a vacuuming process.

[0076] A mold used to manufacture a molded product may, for example, have holes (insertion parts) for fitting locking members. The insertion parts may be provided in both the upper and lower molds, or in only one of them.

[0077] A "locking member" is a component used when setting a knitted fabric base material into a mold or core material. Examples of locking members include pins and hooks. The locking member may remain in the hole of the molded product.

[0078] The molded product may, for example, not include a core material. For example, the molded product may include a tensile reinforcement portion in part or all of the knitted layer and not have a core material layer.

[0079] According to the present invention, it is possible to provide a molded fiber-reinforced composite material that can increase strength and suppress changes in the mechanical properties of the knitted yarn, thereby facilitating the recovery and reuse of the knitted yarn, and a method for manufacturing the molded product.

[0080] This figure shows a molded product according to the first embodiment of the present invention. (a) is a view of the molded product in the thickness direction (plan view), (b) is a cross-sectional view taken along line A1-A1 in Figure 1(a), and (c) is an enlarged view of the main part of Figure 1(b). This figure shows the knit of the molded product of Figure 1. (a) shows the standard knit portion, and (b) shows the reinforced knit portion. This flowchart shows the method for manufacturing the molded product of Figure 1. This schematic diagram shows each step of the manufacturing method of Figure 3. (a) is the gel coat application step, (b) is the first knitted material base set step, (c) is the core material set step, (d) is the second knitted material base set step, (e) is the film back set step, (f) is the molding step, and (g) is the molded product obtained after the molding step in Figure 4(f). This flowchart shows a method for recovering knitted yarn and resin material from a molded product. This figure shows a molded product according to the second embodiment of the present invention. (a) is a plan view, (b) is a cross-sectional view taken along line A2-A2 in Figure 6(a), and (c) is an enlarged view of the main part of Figure 6(b). Figure 6 is a schematic diagram showing each step in the manufacturing method of the molded product. (a) is the core material, (b) is the step of setting the knitted base material into the core material, (c) is the step of setting the core material with the knitted base material into the mold, (d) is the molding step, and (e) is the molded product obtained after the molding step in Figure 7(d).

[0081] The following describes in detail embodiments of the molded article and the method for manufacturing the molded article of the present invention with reference to the drawings. Note that the embodiments described below are merely examples. Furthermore, identical components are denoted by the same reference numerals, and detailed explanations are omitted.

[0082] [Molded article according to the first embodiment] First, with reference to Figure 1, a molded article 10 according to the first embodiment of the present invention will be described. The molded article 10 of this embodiment comprises a resin material 11, two knitted fabric base materials 20 (knitted fabric base material 20A and knitted fabric base material 20B), and one core material 30. In the molded article 10 of this embodiment, a heat-meltable thermoplastic resin is used as the resin material 11.

[0083] The knitted base material 20 is constructed by knitting together a continuous thread-like knitting yarn 21 (see Figure 2). In the molded product 10, the knitted base material 20 is embedded in the resin material 11 over most of the outer shape of the product. Furthermore, in the molded product 10 of this embodiment, the knitted base material 20 is formed three-dimensionally to match the shape of the molded product 10.

[0084] The stitches 22 of the knitted base material 20 will be explained with reference to Figure 2. As shown in Figure 2(a), in the knitted base material 20, the knitting yarn 21 is formed in a loop shape, and loop-shaped portions (stitches 22) are sequentially formed by passing the knitting yarn 21 through these loop-shaped portions. In other words, the knitted base material 20 is composed of continuous stitches 22. Specifically, as shown in Figure 2(a), the knitting yarn 21 forms multiple stitches 22 in the knitted base material 20 that are aligned in the course direction B1 (horizontal direction in Figure 2). For example, the knitting yarn 21 forms a stitch 22a and a stitch 22b adjacent to stitch 22a in the course direction B1 in the knitted base material 20.

[0085] Furthermore, the knitting yarn 21 forms stitches 22c adjacent to stitch 22a in the wale direction B2 (vertical direction in Figure 2), and stitches 22d adjacent to stitch 22b in the wale direction B2. In this way, the knitting yarn 21 forms multiple stitches 22 in the course direction B1 and the wale direction B2, respectively, and is constructed as a knitted base material 20. From another point of view, the knitted base material 20 has stitches 22 formed so that the knitting yarns 21 intersect with each other.

[0086] When no tension is applied to the knitted base material 20, a standard knitted portion 23a is formed on the knitted base material 20, as shown in Figure 2(a). On the other hand, when tension is applied to the knitted base material 20 (in the example shown in Figure 2(b), tension is applied in the wale direction B2), a reinforced knitted portion 23b is formed on the knitted base material 20, as shown in Figure 2(b).

[0087] As shown in Figure 1(b), the molded product 10 of this embodiment comprises a knitted fabric layer 12 formed by impregnating a knitted fabric base material 20 with resin 11 and hardening it, a core material layer 13 containing a core material 30, a surface layer 14 formed by hardening gel coat, and a plurality of holes 15. The plurality of holes 15 are formed to open into the first surface F1 and the second surface F2 and to penetrate the knitted fabric. A portion of the pins 40 remains in the holes 15. The surface layer 14 is formed on the surface (first surface F1) that constitutes the design surface (front surface) of the front and back surfaces of the molded product 10.

[0088] The molded product 10 comprises two knitted layers 12: a first knitted layer 12A containing a knitted base material 20A, and a second knitted layer 12B containing a knitted base material 20B. As shown in Figure 1(c), the molded product 10 is laminated in the thickness direction X from the first surface F1 to the second surface F2 in the order of surface layer 14, first knitted layer 12A, core material layer 13, and second knitted layer 12B. As shown in Figure 1(a), the core material 30 is located in a part of the molded product 10.

[0089] As shown in Figure 1(a), the molded product 10 comprises a portion including a standard knit portion 23a (standard portion 16) and a portion including a reinforced knit portion 23b (tensile reinforced portion 17). As shown in Figure 1(a), the tensile reinforced portion 17 is located inside the position where the multiple holes 15 are formed. The knitted layer 12 other than the tensile reinforced portion 17 is the standard portion 16. As shown in Figures 1(a) and 1(b), the core material 30 (core material layer 13) is arranged along the tensile reinforced portion 17.

[0090] Thus, in the molded product 10, the core material layer 13 is positioned along a portion (tensile reinforcement portion 17) of each of the two knitted layers 12 (first knitted layer 12A and second knitted layer 12B) and between the two knitted layers 12, so as to alleviate the load applied to the knitted layer 12 when a load is applied to the molded product 10. Furthermore, in the molded product 10, the knitted layer 12 includes a tensile reinforcement portion 17 where tension is applied to the knitted base material 20, and the core material layer 13 is positioned along the tensile reinforcement portion 17 and between the two knitted layers 12.

[0091] [Method for Manufacturing a Molded Product According to the First Embodiment] Next, a method for manufacturing a molded product 10 according to the first embodiment will be described. As shown in Figure 3, the manufacturing method according to this embodiment includes a setting step S100 and a molding step S101. In this embodiment, the setting step S100 includes a gel coat application step, a first knitted material base material setting step, a core material setting step, a second knitted material base material setting step, a film bag setting step, and a vacuum drawing step. The molded product 10 includes two knitted material base materials 20, a knitted material base material 20A and a knitted material base material 20B. As shown in Figure 4(e), the mold 110 used in the manufacturing method of the molded product according to this embodiment includes a lower mold 111 and a film bag 112. As shown in Figure 4(a), the lower mold 111 is provided with a plurality of insertion portions 111a. The insertion portions 111a are holes into which pins 40 (locking members) are fitted.

[0092] As shown in Figure 4(a), in the gel coat application process, gel coat is applied to the lower mold 111. The gel coat applied to the lower mold 111 constitutes the surface layer 14.

[0093] Next, as shown in Figure 4(b), in the first knitted fabric base material setting process, the knitted fabric base material 20A is set on the lower mold 111 to which gel coat has been applied. The knitted fabric base material 20A is set on the lower mold 111 while tension is applied. Specifically, the knitted fabric base material 20A is stretched and pins 40 are inserted through the stitches 22. The pins 40 are also fitted into the insertion parts 111a. In other words, the knitted fabric base material 20A is set on the lower mold 111 while tension is applied, by passing the stitches 22 through multiple pins 40 positioned in the insertion parts 111a of the lower mold 111. As a result, the parts of the knitted fabric base material 20A to which tension is applied form reinforced stitch sections 23b (see Figure 4(c)). The reinforced stitch sections 23b are formed inside the multiple positions where the pins 40 are inserted. Furthermore, the knitted base material 20A has standard knitted sections 23a formed in areas other than the reinforced knitted sections 23b (see Figure 4(c)).

[0094] Next, as shown in Figure 4(c), in the core material setting process, the core material 30 is set in the lower mold 111 on which the knitted base material 20A is set. The core material 30 is positioned along the portion of the knitted base material 20A where the reinforced knit portion 23b is formed. Next, as shown in Figure 4(d), in the second knitted base material setting process, the knitted base material 20B is set so as to sandwich the core material 30 between it and the knitted base material 20A. The knitted base material 20B is set in the lower mold 111 under tension, similar to the knitted base material 20A. In this way, in the setting process S100, the knitted base material 20 and the core material 30 are set in the mold 110 under tension and such that the core material 30 is positioned between the knitted base material 20A and the knitted base material 20B (so that a core material layer 13 is formed between the two knitted layers 12). As shown in Figure 4(e), in the film back-setting process, a film back 112 is placed over the lower mold 111 in which the knitted base material 20 and core material 30 are set, and a vacuum is applied. The vacuum creates a gap (cavity C) inside the mold 110 into which the resin material 11 is injected (see Figure 4(f)).

[0095] As shown in Figure 4(f), in the molding process, resin material 11 is injected into the cavity C. When the resin material 11 is injected into the cavity C, it impregnates the knitted base material 20 and hardens to form a knitted layer 12, and a core material layer 13 is formed along the knitted layer 12. After the resin material 11 hardens, the molded product 10 is removed from the mold 110. In this way, a molded product 10 is formed in which the core material layer 13 is positioned between the two knitted layers 12 and along the knitted layers 12 (see Figure 4(g)). In the state after being removed from the mold 110, the portion of the pin 40 that was fitted into the insertion portion 111a protrudes from the surface layer 14, so the protruding portion of the pin 40 is removed by cutting or the like.

[0096] [Method for recovering materials] Next, a method for recovering the braided yarn 21 and the resin material 11 from the molded product 10 will be described. As shown in Figure 5, the process for recovering the braided yarn 21 and the resin material 11 from the molded product 10 includes at least a heating step S200, a separation step S201, and a winding step S202.

[0097] In heating step S200, the molded product 10 is heated to melt the resin material 11. In heating step S200, the resin material 11 of the molded product 10 melts, making it possible to separate the knitted fabric base material 20 from the resin material 11.

[0098] In separation step S201, the knitted fabric base material 20 and the resin material 11 are separated. Specifically, in separation step S201, the knitted fabric base material 20 and the molten resin material 11 are separated by a centrifugal separator (not shown in the figure). After separation, the knitted fabric base material 20 and the resin material 11 are each processed for reuse. The knitted fabric base material 20 is reused as knitting yarn 21 after going through the winding step S202, which will be described below.

[0099] In the winding process S202, the ends of the knitted yarns 21 of the knitted base material 20 (not shown) are pulled to unravel the stitches 22, and the knitted yarns 21 are wound up. Here, in the molded product 10, the knitted yarns 21 are embedded in the resin material 11 without being cut. Therefore, after the resin material 11 is melted, the knitted yarns 21 are recovered while maintaining their length. As a result, the uses of the recovered knitted yarns 21 are broadened.

[0100] [Molded product according to the second embodiment] Next, with reference to Figure 6, a molded product 50 according to the second embodiment of the present invention will be described. The molded product 50 of this embodiment comprises a resin material 11, a knitted base material 51, and a core material 52. The knitted base material 51 is formed by knitting yarn 21.

[0101] The molded product 50 of this embodiment comprises one knitted fabric base material 51 and one core material 52. As shown in Figure 6(b), the molded product 50 comprises a knitted fabric layer 12 formed by impregnating the knitted fabric base material 51 with resin 11 and hardening it, a core material layer 13 containing the core material 52, and a surface layer 14 formed by hardening gel coat. In the molded product 50, one knitted fabric base material 51 is arranged to surround the core material 52, thereby forming two knitted fabric layers 12, a first knitted fabric layer 12A and a second knitted fabric layer 12B, sandwiching the core material layer 13. As shown in Figure 6(c), the molded product 50 is laminated in the order of surface layer 14, first knitted fabric layer 12A, core material layer 13, and second knitted fabric layer 12B in the thickness direction X from the first surface F1 to the second surface F2. As shown in Figure 6(a), the core material 52 is arranged over substantially the entire area of ​​the molded product 50.

[0102] As shown in Figure 6(a), in the molded product 50 of this embodiment, a reinforced knit portion 23b is formed over the entire area of ​​the knitted base material 51. That is, in the molded product 50, a tension-reinforced portion 17 is formed over the entire area of ​​the knitted layer 12. Also, as shown in Figure 6(c), in the molded product 50, the end of the core material layer 13 is surrounded by the knitted base material 51.

[0103] Thus, in the molded product 50, the core material layer 13 is positioned along substantially the entire area of ​​the two knitted layers 12 (first knitted layer 12A and second knitted layer 12B) and between the two knitted layers 12 so as to mitigate the load applied to the knitted layers 12 when a load is applied to the molded product 50. Furthermore, in the molded product 50, the knitted layers 12 include a tension-reinforced portion 17 when tension is applied to the knitted base material 20, and the core material layer 13 is positioned along the tension-reinforced portion 17 and between the two knitted layers 12 so as to mitigate the load applied to the tension-reinforced portion 17 when a load is applied to the molded product 50.

[0104] [Method for Manufacturing a Molded Product According to the Second Embodiment] Next, a method for manufacturing a molded product 50 according to the second embodiment will be described. The manufacturing method of this embodiment includes a setting step S100 and a molding step S101, similar to the manufacturing method of the molded product 10 according to the first embodiment. In this embodiment, the setting step S100 includes a gel coat application step, a step of setting the knitted base material 51 on the core material 52, a step of setting the core material 52 with the knitted base material 51 set on it in the mold 120, and a mold clamping step.

[0105] As shown in Figure 7(a), the core material 52 used in the manufacturing method of this embodiment has a curved portion 52a and a flange portion 52b formed in advance to conform to the shape of the molded product 50. As shown in Figure 7(d), the mold 120 used in the manufacturing method of the molded product of this embodiment includes a lower mold 121 and an upper mold 122.

[0106] The knitted base material 51 used in the manufacturing method of this embodiment is formed in a cylindrical shape. As shown in Figure 7(b), in the step of setting the knitted base material 51 on the core material 52, the core material 52 is set inside the cylindrical knitted base material 51. That is, the knitted base material 51 is set on the core material 52 in advance, and is set on the lower mold 121 with tension applied along the shape of the core material 52. The knitted base material 51 is under tension due to the core material 52 being set inside, and reinforced knitted sections 23b are formed throughout. As shown in Figure 7(c), in the step of setting the core material 52 with the knitted base material 51 set on it into the mold 120, the knitted base material 51, with the core material 52 set on it, is set into the lower mold 121 which has gel coat applied. Next, after the knitted base material 51 and the core material 52 are set into the lower mold 121, the upper mold 122 is brought close to the lower mold 121 and the mold 120 is closed (mold clamping step). When the mold is clamped, the core material 52 is sandwiched between the knitted base material 51. Furthermore, the knitted base material 51 is subjected to additional tension when sandwiched between the mold 120.

[0107] As shown in Figure 7(d), the mold clamping process creates a gap (cavity C) in the mold 120 into which the resin material 11 is injected. As shown in Figure 7(d), in the molding process, the resin material 11 is injected into the cavity C. When the resin material 11 is injected into the cavity C, it impregnates the knitted base material 20 and hardens to form a knitted layer 12, and a core material layer 13 is formed along the knitted layer 12. After the resin material 11 hardens, the molded product 50 is removed from the mold 120. In this way, a molded product 50 is formed in which the core material layer 13 is positioned between the two knitted layers 12 and along the knitted layers 12 (see Figure 7(e)).

[0108] 10 Molded product 11 Resin material 12 Knitted layer 13 Core material layer 15 Hole 17 Tension reinforced part 20 Knitted base material 21 Knitted yarn 23b Reinforced knitted part 30 Core material 40 Pin (locking member) 50 Molded product 51 Knitted base material 52 Core material 110 Mold 120 Mold S100 Setting process S101 Molding process

Claims

1. A molded article of a fiber-reinforced composite material comprising a meltable or decomposable resin material and a knitted layer including a knitted base material in which knitted yarn is knitted, the molded article comprising: a core material layer including a core material having a lower tensile strength than the knitted layer; and two knitted layers, wherein the knitted base material is formed to conform to the shape of the molded article in which the knitted yarn is knitted in a continuous state and the continuity of the knitted yarn is maintained, and the core material layer is positioned along at least a portion of each of the two knitted layers and between the two knitted layers to mitigate the load applied to the knitted layer when a load is applied to the molded article.

2. A molded article according to claim 1, wherein the knitted layer is formed by impregnating the knitted base material with the resin material, and the knitted base material is included throughout the entire thickness of the molded article.

3. A molded article according to claim 1 or 2, wherein the core material is a porous body comprising a plurality of pores, and at least some of the pores being independent of the other pores, and the core material layer contains air by having portions of at least some of the pores in the porous body that are not impregnated with the resin material, so as to mitigate the load applied to the knitted layers when a load is applied to the molded article by the deformation of the pores, and is arranged along at least some of the two knitted layers and between the two knitted layers.

4. A molded article according to any one of claims 1 to 3, wherein one knitted fabric base material is arranged to surround at least a portion of the core material, and the core material layer is arranged between two knitted fabric layers.

5. A molded article according to any one of claims 1 to 4, comprising a surface layer that constitutes the surface of the molded article and protects the knitted layer.

6. A molded article according to any one of claims 1 to 5, wherein the knitted layer includes a tension-reinforced portion when tension is applied to the knitted base material, and the core material layer is arranged along the tension-reinforced portion and between the two knitted layers so as to alleviate the load applied to the tension-reinforced portion when a load is applied to the molded article.

7. The molded article according to claim 6, wherein the molded article includes a plurality of holes formed to open on at least one surface and penetrate the knitted stitches, and the knitted layer has the tension-reinforced portion configured inside the positions where the plurality of holes are formed.

8. The molded article according to claim 7, wherein the knitted base material has a greater thickness in the portion including the edge of the hole than in other portions.

9. A method for manufacturing a molded article, comprising: a setting step of setting a knitted base material and a core material, which are knitted from a continuous yarn, into a mold; and a molding step of forming a molded article by curing a molten or decomposable resin material in the mold after the setting step, wherein in the molding step, the resin material is cured with the core material positioned along the knitted base material under tension, forming a core material layer including the core material between two knitted layers including the resin material and the knitted base material; and in the setting step, the knitted base material and the core material are set into the mold with tension applied to at least a portion of the knitted base material, and the core material layer is formed between the two knitted layers.

10. A method for manufacturing a molded product according to claim 9, wherein in the setting step, the knitted base material is set in the mold in advance by setting it in the core material so that tension is applied along the shape of the core material.

11. A method for manufacturing a molded product according to claim 9, wherein in the setting step, the knitted base material is set against the mold while tension is applied.

12. A method for manufacturing a molded product according to claim 11, wherein in the setting step, the knitted base material is set against the mold while tension is applied, by passing the knitted stitches through a plurality of locking members positioned in the mold.

Images