Preform structure, fiber-reinforced plastic, and method for manufacturing a preform structure

Abstract

A preform structure (10) comprising: a carbon fiber (2); a support layer (1) that serves as a substrate for the carbon fiber (2); and a carbon-based thread (3) for securing the carbon fiber (2) to the support layer (1).

Description

Technical Field

[0001] The present invention relates to a preform structure, a fiber reinforced plastic, and a method for manufacturing a preform structure.

Background Art

[0002] As a fiber reinforced plastic, a preform structure containing reinforcing fibers such as carbon fibers or glass fibers embedded in a resin body is known. Fiber reinforced plastics are used in various fields such as sports goods, leisure goods, automotive materials, aircraft materials, and electronic device members. When high strength is required for the reinforcing fibers, carbon fibers with particularly high strength are used. However, since carbon fibers are difficult to process into a free shape, carbon fiber cloth is used when used in a preform structure.

[0003] On the other hand, various forms of preform structures using reinforcing fibers such as carbon fibers have been studied. For example, Patent Document 1 describes a preform structure in which layers in which reinforcing fiber bundles are aligned and arranged such that their longitudinal directions are in one direction are laminated in two or more layers such that the longitudinal directions of the reinforcing fiber bundles are different. In this preform structure, auxiliary yarns are used as means for restraining the positions of the reinforcing fiber bundles.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the preform structure described in Patent Document 1, layers consisting of reinforcing fiber bundles can be laminated so that the longitudinal angles of the reinforcing fiber bundles are offset. However, since designs other than those described above cannot be created, there was a problem in that the range of design options for improving strength was narrow. Therefore, there is a need for a preform structure with a greater degree of design freedom. In addition, in the preform structure described in Patent Document 1, glass fibers, polyester fibers, and nylon fibers are used as the material for the auxiliary threads. However, since carbon fiber is not used as the auxiliary thread, there was a problem in that the entire structure could not be made of carbon-based materials. Furthermore, depending on the material of the auxiliary thread, there was a problem in that the compatibility with the resin to be impregnated may be poor.

[0006] The object of the present invention is to provide a preform structure containing carbon fiber and offering a high degree of design freedom, a fiber-reinforced plastic, and a method for manufacturing the preform structure. [Means for solving the problem]

[0007] According to one aspect of the present invention, a preform structure is provided that comprises carbon fibers, a support layer that serves as a base for the carbon fibers, and carbon-based threads for securing the carbon fibers to the support layer.

[0008] In a preform structure according to one aspect of the present invention, it is preferable that the carbon-based yarn is at least one selected from the group consisting of carbon nanotube yarn and composite yarn of resin and carbon nanotube yarn.

[0009] In a preform structure according to one aspect of the present invention, it is preferable that the support layer is at least one selected from the group consisting of glass fiber cloth, carbon fiber cloth, resin cloth, and resin film.

[0010] In a preform structure according to one aspect of the present invention, it is preferable that the support layer is at least one selected from the group consisting of glass fiber cloth and carbon fiber cloth.

[0011] In a preform structure according to one aspect of the present invention, it is preferable that the support layer is at least one selected from the group consisting of resin cloth and resin film.

[0012] According to one aspect of the present invention, a fiber-reinforced plastic is provided, comprising a preform structure according to the aforementioned aspect of the present invention and a resin impregnated within the preform structure.

[0013] According to one aspect of the present invention, a fiber-reinforced plastic is provided, comprising a preform structure according to the aforementioned aspect of the present invention and a resin impregnated into the preform structure, wherein the resin that is the material of the resin cloth or the resin film and the resin impregnated into the preform structure are made of the same material.

[0014] According to one aspect of the present invention, a method for manufacturing a preform structure according to one aspect of the present invention is provided, comprising the steps of arranging the carbon fibers on the support layer and securing the carbon fibers to the support layer with the carbon-based yarn.

[0015] In a method for manufacturing a preform structure according to one aspect of the present invention, it is preferable to secure the carbon fiber to the support layer by sewing it with the carbon-based thread.

[0016] In a method for manufacturing a preform structure according to one aspect of the present invention, it is preferable to use an embroidery machine to secure the carbon fibers to the support layer.

[0017] In a method for manufacturing a preform structure according to one aspect of the present invention, it is preferable that the tensile strength of the carbon-based yarn is 500 MPa or more.

[0018] According to one aspect of the present invention, a preform structure including carbon fibers, a fiber reinforced plastic, and a method for manufacturing the preform structure with a high degree of design freedom can be provided.

Brief Description of the Drawings

[0019] [Figure 1] It is a schematic diagram showing a preform structure according to a first embodiment of the present invention. [Figure 2] It is a schematic diagram showing an example of a support layer used in the first embodiment of the present invention. [Figure 3] It is a schematic diagram showing a state where a prepreg is produced using the preform structure according to the first embodiment of the present invention. [Figure 4] It is a schematic diagram showing a fiber reinforced plastic according to the first embodiment of the present invention.

Modes for Carrying Out the Invention

[0020] [First Embodiment] Hereinafter, the present invention will be described based on the drawings by taking embodiments as examples. The present invention is not limited to the content of the embodiments. In the drawings, there are parts illustrated with enlargement or reduction for ease of explanation.

[0021] (Preform Structure) As shown in FIG. 1, the preform structure 10 according to the present embodiment includes carbon fibers 2, a support layer 1 serving as a base for the carbon fibers 2, and a carbon-based yarn 3 for fixing the carbon fibers 2 to the support layer 1. Thus, the carbon fiber 2 has a free design, is disposed on the support layer 1, and is fastened by the carbon-based yarn 3. The carbon fiber 2 is usually used as a carbon fiber cloth. However, in this embodiment, the carbon fiber 2 can be used for the preform structure 10 in a form other than a cloth, thereby increasing the degree of freedom in the design of the carbon fiber 2. For example, when the support layer 1 is a carbon fiber cloth, different preform structures with different carbon fiber designs can be laminated by laminating the carbon fiber 2 on the support layer 1 with a free design.

[0022] (Support layer) The support layer 1 is a layer that serves as a base for the carbon fiber 2. The carbon fiber 2 can be disposed on the support layer 1 with a free design. Examples of the support layer 1 include a glass fiber cloth, a carbon fiber cloth, a resin cloth, and a resin film. Among these, from the perspective of the strength of the preform structure 10, a glass fiber cloth and a carbon fiber cloth are preferred. Further, from the perspective that the entire preform structure 10 can be made of a carbon-based material, a carbon fiber cloth is particularly preferred. When the support layer 1 is a glass fiber cloth or a carbon fiber cloth, for example, as shown in FIG. 2, it may be a cloth woven with warp yarns 11 and weft yarns 12. With such a cloth, the carbon-based yarn 3 can be passed through the weave of the cloth, and the carbon fiber 2 can be fastened with the carbon-based yarn 3.

[0023] (Carbon fiber) The carbon fiber 2 is a fiber obtained by subjecting a precursor of an organic fiber to heat carbonization treatment and composed of 90% or more carbon by mass ratio. The carbon fiber 2 can be produced by using an acrylic fiber or pitch (by-products such as petroleum, coal, and coal tar) as a raw material and carbonizing it at a high temperature. Examples of carbon fiber 2 include PAN-based carbon fiber (carbon fiber using acrylic fiber) and pitch-based carbon fiber (carbon fiber using pitch).

[0024] (Carbon fiber yarn) The carbon-based yarn 3 is a yarn that can penetrate the support layer 1 and contains fibers made of carbon-based material. Note that the carbon-based yarn 3 does not contain the carbon fiber 2 mentioned above. Carbon fiber 2 lacks flexibility and cannot be sewn like yarn. In contrast, the carbon-based yarn 3 can be passed through the weave of carbon fiber cloth, etc., and the carbon fiber 2 can be secured with the carbon-based yarn 3. With such carbon-based yarn 3, by using carbon fiber cloth as the support layer 1, all the materials of the preform structure 10 can be made of carbon-based materials. This further improves the strength of the preform structure 10.

[0025] Examples of carbon-based yarns 3 include carbon nanotube yarns and carbon nanotube composite yarns (sometimes referred to as "CNT composite yarns") made of resin and carbon nanotube yarns. Carbon nanotube yarn can be obtained, for example, by drawing carbon nanotubes in a sheet-like form from the end of a carbon nanotube forest (a growth structure in which multiple carbon nanotubes are grown on a substrate so as to be oriented perpendicular to the substrate, sometimes referred to as an "array"), bundling the drawn carbon nanotube sheets, and then twisting the bundle of carbon nanotubes. In addition, carbon nanotube yarn can also be obtained by spinning from a dispersion of carbon nanotubes. The production of carbon nanotube linear bodies by spinning can be carried out, for example, by the method disclosed in U.S. Patent Publication US 2013 / 0251619 (Japanese Patent Publication No. 2012-126635). From the viewpoint of obtaining high-purity carbon nanotube yarn, it is preferable to obtain carbon nanotube yarn by twisting carbon nanotube sheets. Carbon nanotube yarn may also be a yarn in which two or more carbon nanotube yarns are twisted together.

[0026] Examples of CNT composite yarns include: (1) a yarn obtained by drawing carbon nanotubes in a sheet form from the end of a carbon nanotube forest, bundling the drawn carbon nanotube sheets, and then twisting the bundles of carbon nanotubes, wherein a resin film is provided on the surface of the carbon nanotube forest, sheet, bundle, or twisted yarn; (2) a CNT composite yarn obtained by twisting bundles of carbon nanotubes together with yarn of other materials; and (3) a CNT composite yarn obtained by twisting yarn of other materials with carbon nanotube yarn or CNT composite yarn. Furthermore, while the CNT composite yarn in (3) is a composite yarn obtained by braiding two yarns, it may also be made by twisting together three or more yarns, as long as it contains at least one carbon nanotube or CNT composite yarn.

[0027] When using CNT composite yarn as the carbon-based yarn 3, it is preferable that the resin used for the CNT composite yarn is the same resin impregnated into the preform structure 10. Since such a resin is the same as the resin of the resin layer 4 described later, the CNT composite yarn is more easily impregnated into the resin. If the carbon-based thread 3 is a twisted thread, it is preferable that it is Z-twisted (left-handed). When it is Z-twisted, unraveling of the thread can be suppressed when sewing with the carbon-based thread 3 using an embroidery machine. The diameter of the carbon fiber yarn 3 (or the diameter of the twisted yarn in the case of a twisted yarn) is preferably 50 μm or more and 1000 μm or less. If the diameter of the carbon fiber yarn 3 is within the above range, the carbon fiber yarn 3 can more securely fasten the carbon fiber 2.

[0028] The tensile strength of the carbon-based yarn 3 is preferably 500 MPa or higher. If the tensile strength is 500 MPa or higher, problems such as the yarn breaking when sewing with the carbon-based yarn 3 can be prevented. The tensile strength of carbon fiber yarn 3 can be measured by the following method. Specifically, carbon fiber yarn 3 is cut to a length of 4 cm with a cutter, and 1.5 cm from each end of carbon fiber yarn 3 is fixed to a base with adhesive (Aron Alpha EXTRA 4020, manufactured by Toagosei Co., Ltd.) so that the measurement length is 1 cm, thereby creating a test specimen. The tensile strength is measured by performing the following tensile test using this test specimen. <Tensile Test> For each test specimen, the tensile strength at which the wire breaks will be measured under the following conditions. -conditions- • Tensile and compression testing machine: "RTG-1225" manufactured by A&D Company, Limited. • Tensile speed: 1 mm / min ·Temperature / Humidity: 23℃, 50%RH

[0029] (Method of manufacturing a preform structure) Next, a method for manufacturing the preform structure according to this embodiment will be described. The method for manufacturing the preform structure according to this embodiment is a method for manufacturing the preform structure according to this embodiment, comprising the steps of arranging carbon fibers 2 on a support layer 1 and securing the carbon fibers 2 to the support layer 1 with carbon-based threads 3 (securing step).

[0030] In the fastening process, first, the carbon fiber 2 is placed on the support layer 1. Here, the carbon fiber 2 can be arranged in various shapes. The shape of the carbon fiber 2 may be a spiral shape, as shown in Figure 1, but is not limited to this. Examples of carbon fiber shapes include circular, elliptical, angular (triangular, quadrilateral, pentagonal, and hexagonal shapes), star-shaped, wave-shaped, and linear. Furthermore, the number of carbon fibers 2 is not particularly limited, but it is preferable to have one or more, and from the viewpoint of strength, it is more preferable to have two or more.

[0031] In the fastening process, the carbon fiber 2 is then fastened to the support layer 1 with carbon fiber thread 3. A known method can be used to secure the carbon fiber 2 with the carbon-based thread 3. For example, the carbon fiber 2 may be secured to the support layer 1 by sewing with the carbon-based thread 3. The sewing method may be by hand or by using a machine. Examples of machines that can be used include sewing machines and embroidery machines. Among these, the use of an embroidery machine is preferred.

[0032] (Fiber-reinforced plastic) Next, the fiber-reinforced plastic according to this embodiment will be described. The fiber-reinforced plastic 100 according to this embodiment (see Figure 4) comprises a preform structure 10 according to this embodiment and a resin impregnated into the preform structure 10. Examples of resins used here include thermosetting resins and thermoplastic resins. Examples of thermosetting resins include epoxy resins, polyester resins, phenolic resins, and thermosetting polyimide resins. Among these, epoxy resins are preferred from the viewpoint of strength and other factors. Examples of thermoplastic resins include polypropylene resin, polyphenylene sulfide resin, polycarbonate resin, and thermoplastic polyurethane resin.

[0033] The fiber-reinforced plastic 100 can be manufactured, for example, by a method that includes a lamination process (a process of stacking multiple prepregs 20 as shown in Figure 3).

[0034] In the lamination process, first, a prepreg 20 as shown in Figure 3 is prepared. The prepreg 20 can be manufactured by impregnating the preform structure 10 with resin to form a resin layer 4 that covers the preform structure 10. If the resin used here is a thermosetting resin, an uncured thermosetting resin is used.

[0035] In the lamination process, multiple prepregs 20 are then laminated, as shown in Figure 4. In this way, a base material portion is formed by laminating multiple preform structures 10. The base material portion is impregnated with resin, and the area around the base material portion is also covered with a resin layer 4.

[0036] If the resin is a thermosetting resin, the lamination process may be followed by a step to cure the thermosetting resin. In this way, after the lamination process, the thermosetting resin can be cured to produce the fiber-reinforced plastic 100.

[0037] (Effects of the first embodiment) According to this embodiment, the following effects can be achieved. (1) In this embodiment, the carbon fiber 2 is arranged on the support layer 1 in a free design and secured by carbon fiber thread 3. Therefore, the degree of design freedom for the carbon fiber 2 can be increased. (2) According to this embodiment, a layer made of carbon fiber 2 of a free design can be formed on the support layer 1. Therefore, if the support layer 1 is carbon fiber cloth, a preform structure 10 can be obtained that has two layers: a layer made of carbon fiber cloth and a layer made of carbon fiber 2 of a free design. (3) In this embodiment, if the support layer 1 is carbon fiber cloth, the material of the base material can be entirely carbon-based, and the strength of the base material can be further improved. (4) In this embodiment, delamination between the support layer 1 and the layer made of carbon fiber 2 can be suppressed. For example, if the support layer 1 is a glass fiber cloth, delamination between dissimilar materials, glass fiber and carbon fiber, can be suppressed.

[0038] [Second Embodiment] Next, a second embodiment of the present invention will be described. In this embodiment, the configuration is the same as in the first embodiment except for a different preferred example of the support layer 1. Therefore, the changes will be explained, and other parts common to the previous explanation will be omitted.

[0039] In the preform structure 10 according to this embodiment, the support layer 1 is preferably a resin cloth or a resin film. Furthermore, in the fiber-reinforced plastic 100 according to this embodiment, it is preferable that the resin that is the material of the resin cloth or resin film and the resin impregnated into the preform structure 10 are made of the same material. In this way, the support layer 1 and the resin layer 4 can be integrated. Furthermore, if the resin material of the support layer 1 is a thermoplastic resin, the support layer 1 itself can be used as a resin impregnated into the preform structure 10, and it is not necessary to provide a separate resin layer 4. In addition, a base material portion can be formed that includes a layer made of carbon fiber 2 of any design.

[0040] According to this embodiment, in addition to the effect (1) of the first embodiment, the following effect (5) can be achieved. (5) In this embodiment, since the support layer 1 and the resin layer 4 are made of the same material, the support layer 1 and the resin layer 4 can be integrated. Furthermore, a base material portion can be formed which has a layer made of carbon fiber 2 of any design. Then, a fiber-reinforced plastic 100 having this base material portion can be manufactured.

[0041] [Variations of the Embodiment] The present invention is not limited to the embodiments described above, and any modifications, improvements, etc., that can achieve the objectives of the present invention are included in the present invention. For example, in the embodiment described above, a layer made of carbon fiber 2 was formed only on the upper surface of the support layer 1, but this is not the case. A layer made of carbon fiber 2 may be formed not only on the upper surface of the support layer 1 but also on the lower surface of the support layer 1. In this way, a preform structure can be obtained in which layers made of carbon fiber 2 of any design are provided on both sides of the support layer 1. In the above-described embodiment, the fiber-reinforced plastic 100 was produced by laminating multiple prepregs 20, but the invention is not limited to this. Alternatively, the fiber-reinforced plastic 100 may be produced by laminating multiple preform structures 10 to form a base material portion, and then impregnating this base material portion with resin. Furthermore, in the above-described embodiment, when multiple prepregs 20 were laminated, a process of curing the thermosetting resin was performed after the lamination process, but this is not limited to this. For example, the prepregs 20 may be pressed together with a hot press to cure the thermosetting resin in the lamination process and produce the fiber-reinforced plastic 100. [Explanation of symbols]

[0042] 1...Support layer, 11...Warp threads, 12...Weft threads, 2...Carbon fiber, 3...Carbon-based yarn, 4...Resin layer, 10...Preform structure, 20...Prepreg, 100...Fiber-reinforced plastic.

Claims

1. The device comprises carbon fiber, a support layer that serves as a base for the carbon fiber, and carbon-based threads for securing the carbon fiber to the support layer. The carbon-based yarn is a yarn in which two or more carbon nanotube yarns are twisted together. The yarn formed by twisting together two or more carbon nanotube threads is a Z-twist. Preformed structure.

2. In the preform structure according to claim 1, The support layer is at least one selected from the group consisting of glass fiber cloth, carbon fiber cloth, resin cloth, and resin film. Preformed structure.

3. In the preform structure according to claim 1 or claim 2, The support layer is at least one selected from the group consisting of glass fiber cloth and carbon fiber cloth. Preformed structure.

4. In the preform structure according to claim 1 or claim 2, The support layer is at least one selected from the group consisting of resin cloth and resin film. Preformed structure.

5. A preform structure according to any one of claims 1 to 4, and a resin impregnated into the preform structure, Fiber-reinforced plastic.

6. A preform structure according to claim 4, and a resin impregnated into the preform structure, The resin that is the material of the resin cloth or the resin film and the resin impregnated into the preform structure are made of the same material. Fiber-reinforced plastic.

7. A method for manufacturing a preform structure according to any one of claims 1 to 4, The process includes the steps of arranging the carbon fibers on the support layer and securing the carbon fibers to the support layer with the carbon-based threads. A method for manufacturing preform structures.

8. In the method for manufacturing a preform structure according to claim 7, The carbon fiber is secured to the support layer by sewing with the carbon-based thread. A method for manufacturing preform structures.

9. In the method for manufacturing a preform structure according to claim 7 or claim 8, Using an embroidery machine, the carbon fiber is secured to the support layer. A method for manufacturing preform structures.

10. In the method for manufacturing a preform structure according to claim 7 or claim 8, The tensile strength of the carbon-based yarn is 500 MPa or more. A method for manufacturing preform structures.

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