Carbon fiber reinforced plastic and method for manufacturing the same

Abstract

A carbon fiber-reinforced plastic (100) comprising: a substrate part obtained by stacking a plurality of carbon fiber layers (1) in which carbon fibers have been arrayed in at least one direction; a resin (resin layers (3)) impregnated into the substrate part; and carbon-based threads (2), wherein the carbon-based threads (2) penetrate the plurality of carbon fiber layers (1).

Description

TECHNICAL FIELD

[0001] The present invention relates to a carbon fiber reinforced plastic and a method for producing the same. BACKGROUND ART

[0002] As a carbon fiber reinforced plastic, one in which a plurality of carbon fiber layers are laminated and these layers are embedded in a resin body is known. Such carbon fiber reinforced plastic is attracting attention as a new material because it is lighter and has higher strength than aluminum or iron.

[0003] However, carbon fiber reinforced plastic has a problem that so-called interlayer delamination easily occurs when a shear force acts perpendicularly to the lamination direction of the carbon fiber layers. In order to solve such a problem, for example, Patent Document 1 describes a carbon fiber reinforced plastic including: a plurality of carbon fiber layers made of carbon fibers; a resin body in which the carbon fiber layers are embedded; and pins inserted into and fixed to a plurality of holes formed in the resin body so as to span between the carbon fiber layers. PRIOR ART DOCUMENTS PATENT DOCUMENTS

[0004] Patent Document 1 Japanese Unexamined Patent Publication No. 2011-110796 SUMMARY OF THE INVENTION PROBLEM TO BE SOLVED BY THE INVENTION

[0005] However, production of the carbon fiber reinforced plastic described in Patent Document 1 has a problem in that it requires complicated processes such as a step of forming a plurality of holes in a prepreg laminate and a step of inserting pins into the holes.

[0006] An object of the present invention is to provide a carbon fiber reinforced plastic that can sufficiently suppress interlayer delamination, and a method for producing the same. [Means for solving the problem]

[0007] According to one aspect of the present invention, a carbon fiber reinforced plastic is provided, comprising a base portion having a plurality of carbon fiber layers in which carbon fibers are arranged in at least one direction, a resin impregnated into the base portion, and a carbon-based yarn, wherein the carbon-based yarn penetrates the plurality of carbon fiber layers.

[0008] In a carbon fiber reinforced plastic according to one aspect of the present invention, the resin impregnated into the base material is preferably a thermosetting resin, and it is preferable that the thermosetting resin is an epoxy resin.

[0009] In a carbon fiber reinforced plastic according to one aspect of the present invention, the resin impregnated into the base material is preferably a thermoplastic resin, and the thermoplastic resin is preferably at least one selected from the group consisting of polyamide resin, polypropylene resin, polyphenylene sulfide resin, polycarbonate resin, and thermoplastic polyurethane resin.

[0010] In a carbon fiber reinforced plastic 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 impregnated into the base material portion and carbon nanotube yarn.

[0011] In a carbon fiber reinforced plastic according to one aspect of the present invention, it is preferable that the axial direction of the carbon fibers in at least one carbon fiber layer is not parallel to the axial direction of the carbon fibers in another carbon fiber layer.

[0012] A method for producing carbon fiber reinforced plastic according to one aspect of the present invention is provided, comprising the steps of laminating a plurality of prepregs, each prepreg comprising a carbon fiber layer and a resin impregnated into the carbon fiber layer, and penetrating the plurality of carbon fiber layers with a carbon-based yarn.

[0013] A method for producing carbon fiber reinforced plastic according to one aspect of the present invention is provided, comprising the steps of: laminating a plurality of carbon fiber layers to form a base material; penetrating the plurality of carbon fiber layers with carbon-based yarn; and impregnating the base material with resin.

[0014] In a method for producing carbon fiber reinforced plastic 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.

[0015] According to one aspect of the present invention, it is possible to provide a carbon fiber reinforced plastic that can sufficiently suppress delamination, and a method for producing the same. [Brief explanation of the drawing]

[0016] [Figure 1] This is a schematic diagram showing a carbon fiber reinforced plastic according to a first embodiment of the present invention. [Figure 2] This is a schematic diagram showing a state in which a carbon fiber layer is penetrated by a carbon-based thread in a first embodiment of the present invention. [Figure 3A] This figure illustrates a method for manufacturing carbon fiber reinforced plastic according to the first embodiment of the present invention. [Figure 3B] This figure illustrates a method for manufacturing carbon fiber reinforced plastic according to the first embodiment of the present invention. [Figure 3C] This figure illustrates a method for manufacturing carbon fiber reinforced plastic according to the first embodiment of the present invention. [Figure 4A]FIG. 1 is a diagram for explaining a method for manufacturing a carbon fiber-reinforced plastic according to a second embodiment of the present invention. [Figure 4B] FIG. 2 is a diagram for explaining a method for manufacturing a carbon fiber-reinforced plastic according to a second embodiment of the present invention. [Figure 4C] FIG. 3 is a diagram for explaining a method for manufacturing a carbon fiber-reinforced plastic according to a second embodiment of the present invention. [Figure 5] FIG. 4 is a schematic diagram showing a plurality of carbon fiber layers in which axial directions of carbon fibers are not parallel to each other in a third embodiment of the present invention. [Figure 6A] FIG. 5 is a schematic diagram showing a state where a plurality of carbon fiber layers are stitched using two carbon-based yarns. [Figure 6B] FIG. 6 is a schematic diagram showing a state where a plurality of carbon fiber layers are stitched using two carbon-based yarns. [Figure 6C] FIG. 7 is a schematic diagram showing a state where a plurality of carbon fiber layers are stitched using two carbon-based yarns. DETAILED DESCRIPTION OF THE INVENTION

[0017] First Embodiment Hereinafter, embodiments of the present invention will be described as examples with reference to the drawings. The present invention is not limited to the contents of the embodiments. Note that, in the drawings, some portions are illustrated enlarged or reduced for ease of explanation.

[0018] (Carbon fiber-reinforced plastic) As shown in FIG. 1, a carbon fiber-reinforced plastic 100 according to the present embodiment includes a plurality of carbon fiber layers 1, carbon-based yarns 2, and a plurality of resin layers 3. A base material portion is constituted by the plurality of carbon fiber layers 1. The resin layers 3 are layers formed of a resin impregnated into the base material portion. The carbon-based yarns 2 penetrate the plurality of carbon fiber layers 1 in a substantially perpendicular direction to the carbon fiber layers 1. In this way, the carbon-based thread 2 penetrates multiple carbon fiber layers 1, thereby improving the vertical strength of the carbon fiber layers 1 that are not reinforced by the carbon fiber layers 1. Furthermore, the carbon-based thread 2 can also be used to fasten the carbon fiber layers 1 together. In this manner, delamination in the carbon fiber reinforced plastic 100 can be sufficiently suppressed.

[0019] (Carbon fiber layer) The carbon fiber layer 1 is a layer in which carbon fibers are arranged in at least one direction. The carbon fiber layer 1 may be a carbon fiber cloth. Furthermore, this carbon fiber layer 1 may be a cloth in which warp threads 11 and weft threads 12 are woven, for example, as shown in Figure 2. There may be multiple carbon fiber layers 1, and it may be two layers or three or more layers.

[0020] Carbon fiber is a fiber composed of more than 90% carbon by mass, obtained by heating and carbonizing an organic fiber precursor. Carbon fiber can be produced by carbonizing acrylic fibers or pitch (a by-product of petroleum, coal, and coal tar, etc.) at high temperatures. Examples of carbon fibers include PAN-based carbon fibers (carbon fibers using acrylic fibers) and pitch-based carbon fibers (carbon fibers using pitch). The thickness of the carbon fiber layer 1 is preferably between 100 μm and 5000 μm. Within the aforementioned range of thickness for the carbon fiber layer 1, the carbon fiber yarn 2 can easily penetrate the carbon fiber layer 1.

[0021] (Carbon fiber yarn) Carbon-based yarn 2 is a yarn that can penetrate multiple carbon fiber layers 1 and contains fibers made of carbon-based material. Note that carbon-based yarn 2 does not contain the carbon fibers mentioned above. Carbon fibers lack flexibility and cannot be sewn like yarn. In contrast, as shown in Figure 2, carbon-based yarn 2 can be passed through the weave of the carbon fiber cloth, and multiple carbon fiber layers 1 can be sewn together with carbon-based yarn 2. With such a carbon-based yarn 2, the entire material of the base part can be made of carbon-based material, further improving the strength of the base part.

[0022] Examples of carbon-based yarns 2 include carbon nanotube yarns and carbon nanotube composite yarns (sometimes referred to as "CNT composite yarns") made by combining carbon nanotube yarns with other materials. 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.

[0023] 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.

[0024] When using CNT composite yarn as the carbon-based yarn 2, it is preferable that the other material used in the CNT composite yarn is a resin impregnated into the base material. Since such a resin is the same as the resin of the resin layer 3 described later, when the carbon fiber layer is sewn with the CNT composite yarn and then impregnated with resin, the CNT composite yarn is more easily impregnated with the resin. If the carbon-based thread 2 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 2 using an embroidery machine. The tensile strength of the carbon-based yarn 2 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 2 can be prevented. The diameter of the carbon-based yarn 2 (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-based yarn 2 is within the above range, the carbon fiber layer 1 can be easily sewn with the carbon-based yarn 2. The frequency at which the carbon fiber thread 2 penetrates multiple carbon fiber layers 1 is preferably such that the average distance to adjacent penetration points is between 0.1 mm and 500 mm. If the average distance is within the above range, the strength of the carbon fiber layer 1 in the vertical direction can be improved.

[0025] (Resin layer) The resin layer 3 is a layer made of resin impregnated into the base material. The resin layer 3 is the resin of carbon fiber reinforced plastic 100, and this resin is reinforced by the base material containing the carbon fiber layer 1 and carbon fiber yarn 2. Methods for impregnating the base material with resin include: (1) immersing the carbon fiber layer 1 in resin, removing it, and drying it to impregnate the carbon fiber layer 1 with resin and create a prepreg, and then laminating this prepreg; (2) creating a base material, immersing this base material in resin, removing it, and drying it to impregnate this base material with resin; and (3) creating a base material, placing this base material in a mold, and then injecting resin into the mold to impregnate this base material with resin. Examples of resins 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 polyamide resins, polypropylene resins, polyphenylene sulfide resins, polycarbonate resins, and thermoplastic polyurethane resins. The thickness of the resin layer 3 is preferably 10 μm or more and 1000 μm or less. Within the aforementioned range of thickness for the resin layer 3, the carbon-based yarn 2 can easily penetrate the resin layer 3.

[0026] (Manufacturing method for carbon fiber reinforced plastics) Next, a method for producing carbon fiber reinforced plastic according to this embodiment will be described. The method for manufacturing carbon fiber reinforced plastic according to this embodiment, as shown in Figures 3A to 3C, is a method for manufacturing the carbon fiber reinforced plastic 100 according to this embodiment, comprising the steps of laminating a plurality of prepregs 10 comprising a carbon fiber layer 1 and a resin layer 3 (lamination step), and using carbon fiber yarn 2 to form a plurality of carbon fiber layers 1 This method includes a process that penetrates (penetration process).

[0027] In the lamination process, first, a prepreg 10 as shown in Figure 3A is prepared. The prepreg 10 can be manufactured by impregnating a carbon fiber layer 1 with resin to form a resin layer 3 that covers the carbon fiber layer 1. If the resin used here is a thermosetting resin, an uncured thermosetting resin is used.

[0028] In the lamination process, multiple prepregs 10 are then laminated, as shown in Figure 3B. In this way, a base material portion is formed by laminating multiple carbon fiber layers 1. The base material portion is also impregnated with resin, and the area around the base material portion is covered with a resin layer 3.

[0029] In the penetration process, as shown in Figure 3C, the carbon-based thread 2 penetrates multiple carbon fiber layers 1. The carbon-based thread 2 penetrates the base material, which is made up of multiple stacked carbon fiber layers 1, from the bottom to the top, and then moves in the planar direction of the base material to penetrate from the top to the bottom, thereby sewing the base material with the carbon-based thread 2. As for the method of penetrating the carbon fiber layer 1 with carbon-based thread 2, any known method can be used as appropriate. Specifically, it may be done by hand sewing or by using a device. Examples of devices that can be used here include sewing machines and embroidery machines.

[0030] If the resin is a thermosetting resin, the process may include a step to cure the thermosetting resin after the penetration step. By curing the thermosetting resin after the penetration process, the base material can be easily sewn with carbon-based thread 2 because it is in an uncured state during the penetration process.

[0031] (Effects of the first embodiment) According to this embodiment, the following effects can be achieved. (1) In this embodiment, the carbon-based thread 2 penetrates multiple carbon fiber layers 1, thereby improving the vertical strength of the carbon fiber layers 1 that are not reinforced by the carbon fiber layers 1. Furthermore, the carbon-based thread 2 can also fasten the carbon fiber layers 1 together. In this way, delamination in the carbon fiber reinforced plastic 100 can be sufficiently suppressed. (2) In this embodiment, since there are no problems such as the carbon-based yarn 2 melting due to heat, the strength of the base material can be further improved. (3) In this embodiment, the thermosetting resin is cured after the penetration process. With this configuration, the resin is in an uncured state during the penetration process, so the base material can be easily sewn with the carbon-based thread 2.

[0032] [Second Embodiment] Next, a second embodiment of the present invention will be described with reference to the drawings. In this embodiment, the configuration is the same as in the first embodiment except for the manufacturing method of the carbon fiber reinforced plastic. Therefore, the manufacturing method will be described, and other parts that are common to the previous description will be omitted.

[0033] As shown in Figures 4A to 4C, the method for manufacturing carbon fiber reinforced plastic according to this embodiment is a method for manufacturing the carbon fiber reinforced plastic 100A according to this embodiment, comprising the steps of: forming a base material by laminating a plurality of carbon fiber layers 1 (base material formation step); penetrating the plurality of carbon fiber layers 1 with carbon-based yarn 2 (penetration step); and impregnating the base material with resin (impregnation step).

[0034] In the base material formation process, as shown in Figure 4A, multiple carbon fiber layers 1 are stacked to form the base material.

[0035] In the penetration process, as shown in Figure 4B, the carbon-based thread 2 penetrates multiple carbon fiber layers 1. The carbon-based thread 2 penetrates the base material, which is made up of multiple stacked carbon fiber layers 1, from the bottom to the top, and then moves in the planar direction of the base material to penetrate from the top to the bottom, thereby sewing the base material with the carbon-based thread 2.

[0036] In the impregnation process, as shown in Figure 4C, the resin is impregnated into the base material. In this way, the resin is impregnated into the base material, forming a resin layer 3, and the area around the base material is also covered with the resin layer 3.

[0037] (Effects of the second embodiment) According to this embodiment, in addition to the effects (1) and (2) of the first embodiment, the following effect (4) can be achieved. (4) In this embodiment, the carbon-based thread 2 is passed through the base material portion that is not impregnated with resin. Therefore, the base material portion can be easily sewn with the carbon-based thread 2.

[0038] [Third Embodiment] Next, a third embodiment of the present invention will be described with reference to the drawings. In this embodiment, the configuration is the same as in the first embodiment except for the arrangement of the multiple carbon fiber layers 1 in the substrate portion. Therefore, the changes will be explained, and other parts that are common to the previous explanation will be omitted. In this embodiment, as shown in Figure 5, the axial direction of the carbon fibers in at least one carbon fiber layer 1 (the axial direction of the warp threads 11) and the axial direction of the carbon fibers in another carbon fiber layer (the axial direction of the warp threads 11) are not parallel. In the base material, the strength is higher in the axial direction of the carbon fibers compared to other directions. However, if the axial direction of the carbon fibers is aligned in the base material, the strength may be high in one direction but low in other directions. In contrast, by arranging the carbon fiber layer 1 in the base material as shown in Figure 5, the strength can be increased in various directions.

[0039] (Effects of the third embodiment) According to this embodiment, in addition to the effects (1) to (3) of the first embodiment, the following effect (5) can be achieved. (5) In this embodiment, the axial direction of the warp threads 11 in at least one carbon fiber layer 1 is not parallel to the axial direction of the warp threads 11 in another carbon fiber layer. Therefore, the strength in various directions can be increased in the carbon fiber reinforced plastic 100.

[0040] [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, the sewing method used when sewing the base material with carbon-based thread 2 was a running stitch, but it is not limited to this. The sewing method may be a backstitch or various stitches (overcast, cross stitch, chain stitch, blanket stitch, and knot, etc.). In the embodiment described above, multiple carbon fiber layers 1 were sewn together with a single carbon-based thread 2, but the invention is not limited to this. Multiple carbon fiber layers 1 may be sewn together with two or more carbon-based threads 2. For example, Figures 6A to 6C are schematic diagrams showing a state in which multiple carbon fiber layers 1 are sewn together using two carbon-based threads 2 (upper thread 2A and lower thread 2B). When the strength of the upper thread 2A and the lower thread 2B are approximately the same, both the upper thread 2A and the lower thread 2B penetrate the carbon fiber layer 1, as shown in Figure 6A. For example, if the upper thread 2A is stronger than the lower thread 2B, only the lower thread 2B can penetrate the carbon fiber layer 1, as shown in Figure 6B. Also, if the lower thread 2B is stronger than the upper thread 2A, only the upper thread 2A can penetrate the carbon fiber layer 1, as shown in Figure 6C. [Explanation of Symbols]

[0041] 1...Carbon fiber layer, 11...Warp thread, 12...Weft thread, 2...Carbon-based thread, 2A...Upper thread, 2B...Lower thread, 3...Resin layer, 10...Prepreg, 100, 100A...Carbon fiber reinforced plastic.

Claims

1. The material comprises a base portion having multiple layers of carbon fiber arranged in at least one direction, a resin impregnated into the base portion, and carbon-based yarn. The carbon-based yarn is a carbon nanotube yarn. The carbon-based yarn is a yarn in which two or more carbon nanotube yarns are twisted together, and the twisted yarn is Z-twisted. The tensile strength of the carbon-based yarn is 500 MPa or more. The thickness of the carbon fiber layer is 100 μm or more and 5000 μm or less. The diameter of the carbon-based yarn is 50 μm or more and 1000 μm or less. The carbon-based yarn penetrates through multiple carbon fiber layers, The axial direction of the carbon fibers in at least one carbon fiber layer is not parallel to the axial direction of the carbon fibers in another carbon fiber layer. Carbon fiber reinforced plastic.

2. In the carbon fiber reinforced plastic according to claim 1, The resin impregnated into the aforementioned substrate portion is a thermosetting resin. The thermosetting resin is an epoxy resin. Carbon fiber reinforced plastic.

3. In the carbon fiber reinforced plastic according to claim 1, The resin impregnated into the aforementioned base material portion is a thermoplastic resin. The thermoplastic resin is at least one selected from the group consisting of polyamide resin, polypropylene resin, polyphenylene sulfide resin, polycarbonate resin, and thermoplastic polyurethane resin. Carbon fiber reinforced plastic.

4. A method for producing a carbon fiber reinforced plastic according to any one of claims 1 to 3, A step of laminating multiple prepregs, each comprising the carbon fiber layer and a resin impregnated into the carbon fiber layer, The process includes the step of penetrating a plurality of carbon fiber layers with the carbon-based yarn. A method for manufacturing carbon fiber reinforced plastics.

5. A method for producing a carbon fiber reinforced plastic according to any one of claims 1 to 3, A step of stacking multiple carbon fiber layers to form the base material portion, The process involves penetrating multiple carbon fiber layers with the carbon fiber yarn, The process includes the step of impregnating the base material portion with resin. A method for manufacturing carbon fiber reinforced plastics.

6. In the method for producing carbon fiber reinforced plastic according to claim 4 or claim 5, The tensile strength of the carbon-based yarn is 500 MPa or more. A method for manufacturing carbon fiber reinforced plastics.

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