Continuous fiber reinforced resin

Abstract

To provide a fiber reinforced resin having high gas barrier properties.SOLUTION: In a continuous fiber reinforced resin comprising a plurality of continuous fibers and a resin according to one embodiment of the present invention, the continuous fibers have a flat cross section, and an aspect ratio of the cross section, expressed as a long side length / short side length, is 1.5 or more.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a continuous fiber reinforced resin. [Background technology]

[0002] Patent Document 1 describes a gas tank that has excellent strength and heat resistance and reduced gas permeability, and a method for manufacturing the same. The document describes a gas tank that has an inner shell with gas barrier properties and a pressure-resistant fiber-reinforced plastic (FRP) outer shell that covers the inner shell, where the outer shell is made of (A) reinforcing fiber bundles, (B) a thermosetting resin, and (C) elastomer particles and / or thermoplastic resin particles, and the (C) elastomer particles and / or thermoplastic resin particles dispersed in the (B) thermosetting resin are present within the (A) reinforcing fiber bundles. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-63015 Summary of the Invention [Problem to be solved by the invention]

[0004] As described above, gas tanks for high-pressure gases such as high-pressure hydrogen, which have an inner shell with gas barrier properties and an outer shell made of a fiber-reinforced resin layer with pressure resistance, are known. Such gas tanks are lighter than metal gas tanks. In contrast, to further reduce weight and manufacturing costs, single-layer gas tanks have been proposed in which the outer shell is provided with gas barrier properties and the inner shell is omitted. However, in the case of conventional gas tanks, gas barrier properties are not required for the outer shell; rather, a certain level of gas permeability is required to prevent gas that has passed through the inner shell from accumulating between the inner and outer shells. For this reason, the fiber-reinforced resin used for the outer shell has the problem of low gas barrier properties.

[0005] Therefore, an object of the present invention is to provide a fiber-reinforced resin having high gas barrier properties. [Means for solving the problem]

[0006] The present inventors have investigated various means for solving the above-mentioned problems. They have found that a continuous fiber reinforced resin containing a plurality of continuous fibers and a resin, wherein the aspect ratio of the fiber cross section, expressed as the long side length / short side length, is 1.5 or more, i.e., the continuous fiber reinforced resin containing continuous fibers with a flat fiber cross section, has higher gas barrier properties than conventional fiber reinforced resins. Based on this finding, the present inventors have completed the present invention.

[0007] That is, the present invention includes the following embodiments. (Embodiment 1) A continuous fiber reinforced resin comprising a plurality of continuous fibers and a resin, The continuous fiber has a flat cross section, and an aspect ratio of the cross section, expressed as long side length / short side length, of 1.5 or more. The continuous fiber reinforced resin. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a fiber reinforced resin having high gas barrier properties. [Brief explanation of the drawings]

[0009] [Figure 1] 1A and 1B show cross-sectional views of a continuous fiber reinforced resin according to an embodiment of the present invention, taken along a direction perpendicular to the axis of the continuous fiber. In the figure, A is a cross-sectional view showing an embodiment of the continuous fiber reinforced resin according to an embodiment of the present invention, and B is a cross-sectional view showing a conventional continuous fiber reinforced resin. Arrows in the figure indicate gas diffusion paths. [Figure 2] This shows a photograph of the resin molded articles produced in Experiment I. In the figure, A is a molded article made of continuous glass fiber reinforced epoxy resin, and B is a molded article made of continuous carbon fiber reinforced epoxy resin. DETAILED DESCRIPTION OF THE INVENTION

[0010] Preferred embodiments of the present invention will now be described in detail.

[0011] One aspect of the present invention relates to a continuous fiber reinforced resin. The continuous fiber reinforced resin of this aspect includes a plurality of continuous fibers and a resin. Compared to discontinuous fiber reinforced resin, continuous fiber reinforced resin has a smaller directivity of gas in a cross section in the axial direction of the fiber and a longer gas diffusion path. For this reason, continuous fiber reinforced resin is known to have higher gas barrier properties than discontinuous fiber reinforced resin.

[0012] FIG. 1 shows a cross-sectional view of one embodiment of the continuous fiber reinforced resin of this embodiment, taken in a direction perpendicular to the axis of the continuous fiber. As shown in FIG. 1A, the continuous fiber reinforced resin 10 of this embodiment includes a plurality of continuous fibers 11 and a resin 12, and the plurality of continuous fibers 11 have a flat cross section. In contrast, as shown in FIG. 1B, a conventional continuous fiber reinforced resin 20 includes a plurality of continuous fibers 21 and a resin 22, and the plurality of continuous fibers 21 have a circular cross section. Due to this difference in cross-sectional shape, the continuous fiber reinforced resin of this embodiment has a smaller perpendicularity of gas in the cross section perpendicular to the axis of the continuous fiber, and the gas diffusion path (indicated by the arrow in the figure) is longer, compared to the conventional continuous fiber reinforced resin. Therefore, the continuous fiber reinforced resin of this embodiment can have high gas barrier properties.

[0013] In the continuous fiber reinforced resin of this embodiment, the continuous fibers have an aspect ratio, expressed as the long side length / short side length in the cross section, of 1.5 or more, preferably 2.0 or more, and more preferably 3.0 or more. If the aspect ratio in the cross section of the continuous fiber is less than the above-mentioned lower limit, the gas will tend to flow more orthogonally in the cross section perpendicular to the axis of the continuous fiber, which may shorten the gas diffusion path. Therefore, by including a plurality of continuous fibers whose aspect ratio in the cross section is equal to or greater than the above-mentioned upper limit, the continuous fiber reinforced resin of this embodiment can have high gas barrier properties.

[0014] In the continuous fiber reinforced resin of this embodiment, the cross-sectional shape and aspect ratio of the continuous fibers can be determined, for example, by observing the cross section of the continuous fiber reinforced resin using a scanning electron microscope and measuring the long side length and short side length of the cross section of multiple continuous fibers.

[0015] In the continuous fiber reinforced resin of this embodiment, the continuous fibers are preferably inorganic fibers such as carbon fibers, glass fibers, silicon carbide fibers, or basalt fibers, and more preferably carbon fibers or glass fibers. The continuous fiber reinforced resin of this embodiment may contain only one type of continuous fiber exemplified above, or may contain a combination of two or more types.

[0016] In the continuous fiber reinforced resin of this embodiment, the fiber volume content (Vf) of the continuous fibers is preferably 50% or more, more preferably in the range of 50 to 80%, and even more preferably in the range of 50 to 70%. If the fiber volume content of the continuous fibers is less than the lower limit, the gas barrier properties may be reduced. If the fiber volume content of the continuous fibers exceeds the upper limit, the weight of the continuous fiber reinforced resin may be increased. Therefore, by ensuring that the fiber volume content of the continuous fibers is within the above range, the continuous fiber reinforced resin of this embodiment can have high gas barrier properties.

[0017] In the continuous fiber reinforced resin of this embodiment, the fiber volume content of the continuous fibers can be determined, for example, by recovering continuous fibers from resin contained in a predetermined volume of continuous fiber reinforced resin and measuring the volume of the continuous fibers.

[0018] In the continuous fiber reinforced resin of this embodiment, the resin can be appropriately selected from any resin commonly used in the art. Examples of resins contained in the continuous fiber reinforced resin of this embodiment include epoxy resin, polyamide 6 (PA6) resin, polyamide 66 (PA66) resin, aromatic polyamide resin, polyurethane resin, and unsaturated polyester resin. The resin contained in the continuous fiber reinforced resin of this embodiment is preferably an epoxy resin. By containing the resins exemplified above, the continuous fiber reinforced resin of this embodiment can have high gas barrier properties.

[0019] The continuous fiber reinforced resin of this embodiment can be produced by mixing a plurality of continuous fibers with a resin, for example, by impregnating the plurality of continuous fibers with the resin using a filament winding method.

[0020] The continuous fiber reinforced resin of this embodiment can be applied to a molded article of any shape. An example of a molded article of the continuous fiber reinforced resin of this embodiment is a gas tank. When the molded article of the continuous fiber reinforced resin of this embodiment is applied to a gas tank, part or all of the gas tank can be configured with the molded article of the continuous fiber reinforced resin of this embodiment. For example, in the case of a gas tank having an inner shell with gas barrier properties and a pressure-resistant outer shell provided to cover the inner shell, it is preferable that the outer shell is formed with the molded article of the continuous fiber reinforced resin of this embodiment. Alternatively, a gas tank with a single-layer structure omitting the inner shell may be formed with the molded article of the continuous fiber reinforced resin of this embodiment. By applying the molded article of the continuous fiber reinforced resin of this embodiment to a gas tank with a single-layer structure, it is possible to achieve further weight reduction and reduce manufacturing costs compared to conventional gas tanks.

[0021] As described in detail above, the continuous fiber reinforced resin of one aspect of the present invention has high gas barrier properties. Further, since the continuous fiber reinforced resin of one aspect of the present invention contains a plurality of continuous fibers, it also has low weight and high pressure resistance. Therefore, the continuous fiber reinforced resin of one aspect of the present invention can be applied to, for example, a molded body such as a gas tank for storing fuel in vehicles, houses, transportation machinery, and the like.

Examples

[0022] Hereinafter, the present invention will be described more specifically using examples. However, the technical scope of the present invention is not limited to these examples.

[0023] <I: Production of Fiber Reinforced Resin> As continuous fibers, continuous glass fibers (average aspect ratio of fiber cross-section: 3.5) and continuous carbon fibers (average aspect ratio of fiber cross-section: 1) were prepared. The aspect ratio of the fiber cross-section is the ratio represented by the long side length / short side length in the fiber cross-section. Further, as discontinuous fibers, carbon fiber fillers (average diameter: 10.5 μm, average length: 263 μm, average aspect ratio of filler: 25) were prepared. The aspect ratio of the filler is the ratio represented by the length / diameter of the filler. Using the filament winding method, continuous glass fibers or continuous carbon fibers were arranged in a certain direction, and the fibers were impregnated with an epoxy resin to obtain molded bodies of continuous glass fiber reinforced epoxy resin and continuous carbon fiber reinforced epoxy resin. The fiber volume content (Vf) was 68% in both cases. Further, the carbon fiber filler and the epoxy resin were kneaded and injection molded to obtain a molded body of discontinuous carbon fiber reinforced epoxy resin. Vf was 30%. Furthermore, as a blank not containing fibers, a molded body was produced using only an epoxy resin or a PA6 resin. Photographs of the produced resin molded bodies are shown in FIG. 2. In the figure, A is a molded body of continuous glass fiber reinforced epoxy resin, and B is a molded body of continuous carbon fiber reinforced epoxy resin.

[0024] <II: Physical Property Measurement Test of Fiber Reinforced Resin> Using the differential pressure method hydrogen permeability coefficient measurement test (ISO 15106-5), the hydrogen permeability coefficient ((cm 3 cm) / (cm 2 The hydrogen permeability coefficients of the resin molded bodies were measured. Table 1 shows the measured hydrogen permeability coefficients of the resin molded bodies.

[0025] [Table 1]

[0026] As shown in Table 1, the continuous fiber reinforced resin molded body exhibited a lower hydrogen permeability coefficient than the discontinuous carbon fiber reinforced resin molded body and the resin-only molded body. In particular, the continuous glass fiber reinforced epoxy resin molded body containing continuous glass fibers with an average aspect ratio of 3.5, i.e., a flat fiber cross section, exhibited a lower hydrogen permeability coefficient than the continuous carbon fiber reinforced epoxy resin molded body containing continuous carbon fibers with an average aspect ratio of 1, i.e., a circular fiber cross section.

[0027] The present invention is not limited to the above-described embodiments, but includes various modifications. For example, the above-described embodiments have been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to those including all of the described configurations. Furthermore, it is possible to add, delete, and / or replace part of the configuration of each embodiment with other configurations. [Explanation of symbols]

[0028] 10...continuous fiber reinforced resin of the present invention, 20...conventional continuous fiber reinforced resin, 11, 21...continuous fiber, 12, 22...resin

Claims

[Claim 1] A continuous fiber reinforced resin comprising a plurality of continuous fibers and a resin, The continuous fiber has a flat cross section, and an aspect ratio of the cross section, expressed as the long side length / short side length, of 1.5 or more. The continuous fiber reinforced resin.

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