Fiber resin composite sheet, and method of manufacturing the same

Abstract

To provide a method of manufacturing a fiber resin composite sheet provided with both strength and flexibility.SOLUTION: A method of manufacturing a fiber resin composite sheet is disclosed including: a preparation step S1 of preparing a fabric-shaped sheet formed by crossing a first fibrous material and a second fibrous material the same as or different from the first fibrous material; a lamination step S3 of laminating a plurality of the fabric-shaped sheets in a thickness direction to obtain a laminate having a plurality of sheet layers; an impregnation step S5 of impregnating the fabric-shaped sheet with the resin material; and, after the impregnation step S5, a curing step S6 of curing the resin material used for impregnation while the first fibrous material and the second fibrous material keep the fabric shape.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a fiber-resin composite sheet and a method for producing the same. [Background technology]

[0002] Conventionally, fiber-reinforced plastics (FRP) composite sheets containing a fiber material and a resin material have been known (see, for example, Patent Documents 1 to 3). For example, Patent Document 1 discloses a method for producing a carbon-resin composite material (CFRP: Carbon Fiber Reinforced Plastics or CFRTP: Carbon Fiber Reinforced Thermo Plastics) including a step of preparing a composite structure in which carbon linear bodies containing a carbon material and resin linear bodies containing a resin are regularly arranged, and a step of heating the composite structure to melt the resin linear bodies. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 7222989 [Patent Document 2] Patent No. 6242189 [Patent Document 3] Patent No. 6270731 Summary of the Invention [Problem to be solved by the invention]

[0004] According to the inventor's investigations, in the technology of Patent Document 1, when a soft (e.g., low-melting-point) resin linear body is used, the strength of the carbon resin composite material is sometimes insufficient. On the other hand, when a hard resin linear body is used, the flexibility of the carbon resin composite material is insufficient, making it difficult to deform its shape.

[0005] The present invention has been made in view of the above points, and its main object is to provide a fiber-resin composite sheet having both strength and flexibility, and a method for producing the same. [Means for solving the problem]

[0006] The present invention provides a method for producing a fiber resin composite sheet, including: a preparation step of preparing a woven sheet formed by crossing a first fiber material with a second fiber material that is the same as or different from the first fiber material; a lamination step of laminating a plurality of layers of the woven sheet in the thickness direction to obtain a laminate having a plurality of sheet layers; an impregnation step of impregnating the woven sheet with a resin material; and a curing step of curing the impregnated resin material after the impregnation step, while the first fiber material and the second fiber material maintain the woven form.

[0007] The present invention also provides a fiber-resin composite sheet comprising: a laminate formed by laminating, in the thickness direction, a plurality of woven sheet layers each formed by crossing a first fiber material with a second fiber material that is the same as or different from the first fiber material; and a cured product of a resin material impregnated into the laminate. [Effects of the Invention]

[0008] According to the present invention, a fiber-resin composite sheet that is both high in strength and flexibility can be realized. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a flowchart showing a manufacturing method according to one embodiment. [Figure 2] FIG. 2 is a plan view schematically showing a woven sheet according to one embodiment. [Figure 3] FIG. 3 is a plan view schematically showing a method of use according to one embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Preferred embodiments of the present invention will be described below with reference to the drawings. It should be noted that the embodiments described here are, of course, not intended to limit the present invention in any way. Furthermore, the same reference numerals are used to designate components and parts that perform the same function, and redundant explanations may be omitted or simplified as appropriate. Furthermore, in this specification, the expression "A to B" (A and B are arbitrary numerical values) indicating a range means greater than or equal to A and less than or equal to B, and also encompasses the meanings of "greater than A" and "smaller than B."

[0011] <Method of manufacturing fiber-resin composite sheet> FIG. 1 is a flowchart showing a method for manufacturing a fiber-resin composite sheet according to one embodiment. As shown in FIG. 1, the manufacturing method according to this embodiment includes, in this order, a preparation step S1, a cutting step S2, a lamination step S3, a stitching step S4, an impregnation step S5, and a curing step S6. However, as will be described in the modified examples below, the order of the steps is not particularly limited unless otherwise specified in this specification. Furthermore, the cutting step S2 and the stitching step S4 are not essential and may be omitted in other embodiments. Furthermore, the manufacturing method disclosed herein may include other steps as necessary.

[0012] The preparation step S1 is a step of preparing a woven sheet made by crossing a first fibrous material with a second fibrous material, which may be the same as or different from the first fibrous material. The woven sheet is typically produced by combining the first fibrous material and the second fibrous material lengthwise and widthwise (perpendicularly). The woven sheet may be prepared by purchasing a commercially available product, or may be produced by hand using a conventionally known method. The weaving method of the woven fabric is not particularly limited, and may be plain weave, twill weave, or satin weave. Typically, one of the first fibrous material and the second fibrous material forms the warp thread (vertical thread) and the other forms the weft thread (horizontal thread).

[0013] FIG. 2 is a plan view schematically illustrating a woven sheet according to one embodiment. In FIG. 2, a first fibrous material forms weft threads (horizontal threads) and a second fibrous material forms warp threads (vertical threads). The first fibrous material extends in a first direction X. The second fibrous material extends in a second direction Y perpendicular to the first direction X. The first fibrous material and the second fibrous material are woven alternately here. The first fibrous material and the second fibrous material are plain woven. Note that while the woven sheet is composed of two types of fibrous materials here, in other embodiments, the second fibrous material may be mixed in the weft threads (horizontal threads), for example, in a smaller number than the first fibrous material, and the first fibrous material may be mixed in the warp threads (vertical threads), for example, in a smaller number than the second fibrous material. The warp threads (vertical threads) and / or weft threads (horizontal threads) may further include a third fiber material different from the first fiber material and the second fiber material.

[0014] The fiber material must be able to maintain its woven state even after undergoing the curing step S6 described below. Therefore, the fiber material must not dissolve in the resin material, for example, in the impregnation step S5 described below. Furthermore, when heat curing is performed in the curing step S6 described below, the fiber material must not melt when heated; in other words, the melting point of the fiber material (or the decomposition initiation temperature based on thermogravimetric analysis) must be higher than the maximum temperature during heat curing in the curing step S6. As long as this requirement is met, any fiber material known to be usable for this type of application can be used without any particular limitation.

[0015] In some embodiments, the melting point (or decomposition onset temperature) of the fiber material is preferably 200°C or higher, more preferably 300°C or higher, and even more preferably 400°C or higher. The fiber material may be a natural fiber such as a plant fiber or an animal fiber, or a chemical fiber. The chemical fiber may be an inorganic fiber or an organic fiber. The properties of the fiber material (e.g., length and diameter) may be within a range that allows a woven sheet to be formed, and are design factors that can be appropriately selected taking into consideration, for example, the application of the fiber-resin composite sheet.

[0016] As inorganic fibers, fibers known to be usable for this type of application can be used without any particular limitation. Inorganic fibers have higher melting points and heat resistance, and are characterized by high hardness and strength compared to organic fibers. Representative examples of inorganic fibers include carbon (including PAN-based and pitch-based) fibers, carbon nanotube (CNT) fibers, glass fibers, ceramic fibers, metal fibers, and mineral fibers.

[0017] As the organic fiber, any fiber known to be usable for this type of application can be used without any particular limitation. The organic fiber may be a regenerated fiber, a semi-synthetic fiber, or a synthetic fiber. Representative examples of organic fibers include aramid (including para- and meta-type) fibers, pulp fibers, cellulose fibers, acetate fibers, polyamide fibers, polyarylate fibers, poly(p-phenylenebenzobisoxal) (PBO) fibers, poly(p-phenylenebenzobisthiazole) (PBZT) fibers, high-molecular-weight polyethylene fibers, polyetheretherketone fibers, polyvinyl alcohol fibers, polyurethane fibers, and the like.

[0018] In some embodiments, at least one of the first fiber material and the second fiber material is preferably a high-strength, high-elasticity fiber (so-called super fiber) having a tensile strength of 2 GPa or more and an elastic modulus of 50 GPa or more. The super fiber may be an inorganic fiber or an organic fiber. Typical examples of super fiber include inorganic fibers such as carbon fiber, CNT fiber, and glass fiber, and organic fibers such as aramid fiber, polyarylate fiber, PBO fiber, PBZT fiber, high-molecular-weight polyethylene fiber, polyether ether ketone fiber, and polyvinyl alcohol fiber.

[0019] In some embodiments, the first fiber material is preferably a high-thermal-conductivity fiber having a thermal conductivity of 10 W / m·K or more (e.g., 20 to 100 W / m·K, for example, 50±10 W / m·K), and the second fiber material is preferably a low-thermal-conductivity fiber having a thermal conductivity of less than 1 W / m·K (e.g., 0.1 to 0.95 W / m·K, for example, 0.6 to 0.7 W / m·K). This allows the thermal conductivity of the fiber-resin composite sheet to be suitably different between the stretching direction of the first fiber material (first direction X) and the stretching direction of the second fiber material (second direction Y).

[0020] In some embodiments, the first fiber material is preferably a conductive fiber and the second fiber material is preferably an insulating fiber, which allows the electrical conductivity of the fiber-resin composite sheet to be preferably different between the stretching direction of the first fiber material (first direction X) and the stretching direction of the second fiber material (second direction Y).

[0021] In some embodiments, it is preferred that the first fibrous material comprises inorganic fibers and the second fibrous material comprises organic fibers. The inclusion of inorganic fibers can improve at least one of the strength, durability, and heat resistance of the woven sheet. The inclusion of organic fibers can improve at least one of the lightness and flexibility of the woven sheet. Furthermore, in some embodiments, it is preferred that both the first fibrous material and the second fibrous material are inorganic fibers.

[0022] As the first fiber material, it is preferable to use fibers containing a carbon material (carbon fibers or CNT fibers) because they are lightweight, have high hardness and strength, and have excellent dimensional stability and heat resistance, etc. Among them, it is more preferable to use CNT fibers because they are lightweight and have high flexibility, etc.

[0023] In some embodiments, it is preferable to use fibers different from the first fiber material as the second fiber material. For example, when the first fiber material is a fiber containing a carbon material (e.g., carbon fiber or CNT fiber), it is preferable to use fibers other than those containing a carbon material as the second fiber material. This allows the properties of the fiber-resin composite sheet to be suitably different between the stretching direction of the first fiber material (first direction X) and the stretching direction of the second fiber material (second direction Y). In some embodiments, it is preferable to use aramid fiber as the second fiber material because it has a high melting point, hardness, strength, and excellent heat resistance. In addition, in some embodiments, it is preferable to use glass fiber as the second fiber material because it has a high melting point, hardness, strength, and excellent heat resistance.

[0024] The properties of the woven sheet (e.g., thickness, weight, weave density, etc.) are design factors that can be appropriately changed in consideration of the physical properties of the fiber-resin composite sheet (e.g., electrical conductivity, thermal conductivity, hardness, tear strength, flexibility, etc.) and the intended use. Therefore, although not particularly limited, the average thickness of the woven sheet is preferably 0.1 to 2.0 mm, and in one example, 0.5 mm. The weight per unit area of ​​the woven sheet is preferably 50 to 500 g / m. 2 This makes it easier to achieve the effects of the techniques disclosed herein at a high level.

[0025] The weave density of the first fiber material (e.g., fiber containing a carbon material) is preferably 5 to 500 fibers / cm, more preferably 100 to 300 fibers / cm, and in one example, 150 fibers / cm. When the first fiber material is a highly conductive fiber (e.g., fiber containing a carbon material), the conductivity in the first direction X can be suitably adjusted by the weave density. For example, increasing the weave density can improve the conductivity, and decreasing the weave density can decrease the conductivity. Furthermore, when the first fiber material is a highly thermally conductive fiber (e.g., fiber containing a carbon material), the thermal conductivity in the first direction X can be suitably adjusted by the weave density. For example, increasing the weave density can improve the thermal conductivity, and decreasing the weave density can decrease the thermal conductivity.

[0026] The weave density of the second fiber material (e.g., aramid fiber) is preferably 5 to 500 threads / cm, more preferably 1 to 100 threads / cm, and in one example, 5 threads / cm. The weave density of the second fiber material is preferably lower than the weave density of the first fiber material. When the second fiber material is organic fiber (e.g., aramid fiber), the thermal conductivity in the in-plane direction, planar strength, and flexibility of the fiber-resin composite sheet can be suitably adjusted by the weave density.

[0027] The cutting step S2 is an optional step. The cutting step S2 is a step of cutting the woven sheet to a predetermined size. Typically, the cutting step S2 is a step of cutting the woven sheet along a thickness direction perpendicular to the stretching direction (first direction X) of the first fiber material and the stretching direction (second direction Y) of the second fiber material to produce multiple woven sheets. By performing this step before the laminating step S3 described later, as in this embodiment, the stacking of multiple sheet layers is less likely to shift, improving workability and dimensional stability. Furthermore, by performing this step before the impregnation step S5 described later, each sheet layer can be thoroughly impregnated with the resin material. Note that the cutting method for the woven sheet may be the same as conventional and is not limited in any way. Furthermore, the size to which the woven sheet is cut is a design factor that can be appropriately changed taking into account, for example, the application of the fiber-resin composite sheet.

[0028] The lamination step S3 is a step of laminating a plurality of woven sheets in the thickness direction to obtain a laminate having a plurality of sheet layers. Here, it is a step of laminating a plurality of woven sheets cut in the cutting step S2 in the thickness direction. However, if the cutting step S2 is not included, for example, a single woven sheet may be alternately folded at predetermined intervals to be laminated in a zigzag (bellows) shape. This allows for the production of a laminate having a plurality of sheet layers laminated in the thickness direction.

[0029] The laminate typically has a rectangular parallelepiped shape. The number N of laminated sheet layers is not particularly limited as long as it is 2≦N, and is a design factor that can be appropriately changed taking into consideration, for example, the thickness, physical properties, and application of the target fiber-resin composite sheet. The laminate is preferably held in place by a jig such as a clamp or temporarily fixed with tape to prevent the multiple sheet layers from shifting.

[0030] In some embodiments, it is preferable to laminate multiple woven sheets so that the stretching direction (first direction X) of the first fiber material coincides with that of the second fiber material, thereby making it possible to favorably differentiate the properties (e.g., electrical conductivity or thermal conductivity) of the fiber-resin composite sheet between the stretching direction (first direction X) of the first fiber material and the stretching direction (second direction Y) of the second fiber material.

[0031] The sewing step S4 is a step that must be performed after the laminating step S3. Here, it is a step that is performed subsequent to the laminating step S3. The sewing step S4 is an optional step. The sewing step S4 is a step in which the multiple sheet layers that have been laminated in the laminating step S3 are sewn together in the thickness direction with a sewing thread. This improves the unity of the multiple sheet layers in the thickness direction, and ultimately increases the strength and dimensional stability of the fiber-resin composite sheet in the thickness direction. The method for sewing the sheet layers is not limited in any way, and can be performed by hand sewing or machine sewing using a sewing machine, for example.

[0032] In some embodiments, the suture thread is preferably made of at least one of a first fiber material (e.g., fiber containing a carbon material) and a second fiber material (e.g., aramid fiber), and more preferably made of the first fiber material (e.g., fiber containing a carbon material). When the first fiber material is a highly thermally conductive fiber (e.g., fiber containing a carbon material), this increases thermal conductivity in the thickness direction, facilitating thermal diffusion within the fiber-resin composite sheet. When the second fiber material is a low-thermal-conductivity fiber (e.g., organic fiber), this further increases the orientation of thermal conduction in the stretching direction (first direction X) of the first fiber material. The stitching density of the suture thread is a design factor that can be appropriately changed in consideration of the physical properties (e.g., electrical conductivity, thermal conductivity, hardness, tear strength, flexibility) and application of the fiber-resin composite sheet. Although not particularly limited, the stitching density of the suture thread is preferably 10 to 500 stitches / cm, more preferably 100 to 300 stitches / cm. In some embodiments, the stitch density of the suture is preferably less than the weave density of the first fiber material. In some embodiments, the stitch density of the suture is preferably greater than the weave density of the second fiber material.

[0033] The impregnation step S5 is a step of impregnating a woven sheet with a resin material. Here, a laminate consisting of multiple sheet layers (specifically, a laminate sewn together in the thickness direction in the stitching step S4) is impregnated with the resin material. As the resin material, one or more materials known to be suitable for this type of application can be used without any particular limitation, as long as they do not dissolve the fiber material used in the preparation step S1 and have a curing temperature lower than the melting point (or the decomposition onset temperature based on thermogravimetric analysis) of the fiber material. Therefore, although suitable fiber materials vary depending on the type of fiber material, examples include thermoplastic resins such as silicone resin, polyamide resin, polypropylene resin, polycarbonate resin, and polyphenylene sulfide resin, as well as thermosetting resins such as epoxy resin, phenolic resin, polyester resin, and polyimide resin. Among these, thermoplastic resins are preferred from the standpoint of flexibility, and silicone resins are more preferred.

[0034] The impregnation method may be the same as the conventional method for impregnating a CNT sheet, as described in Patent Document 2, and is not limited thereto. One example is an impregnation method in which the laminate is immersed in a solution of a resin material. The solution may contain additives (e.g., curing agents) known to be useful for this type of application. Furthermore, in the impregnation method, operations to enhance the permeability of the solution, such as ultrasonic irradiation, decompression, or heating, may be performed as long as the resin material does not significantly harden. Because the laminate has a structure in which multiple sheet layers are stacked, surface tension makes it difficult for the solution to penetrate into the fine voids. Therefore, by performing such operations, air can be removed from the fine voids, allowing the laminate to be thoroughly impregnated with the solution (resin material).

[0035] The curing step S6 is a step that must be performed after the impregnation step S5. Here, it is a step that is performed subsequent to the impregnation step S5. However, in other embodiments, other steps may be included between the impregnation step S5 and the curing step S6. The curing step S6 is a step of curing the resin material impregnated into the first fiber material and the second fiber material while maintaining the woven state. Here, it is a step of curing the resin material impregnated into the laminate in the impregnation step S5. The method of curing the resin material may be the same as conventional methods and is not limited in any way. For example, if a (thermosetting) resin material that requires heating for curing is used in the impregnation step S5, it may be heated at a temperature and for a time required for curing. For example, if a thermosetting silicone resin is used, it may be held at 100°C or higher, for example, 100 to 150°C, for one hour. On the other hand, if a room-temperature-curing resin material is used, it may be left at room temperature (typically 25±5°C) for the required time. In this manner, a fiber-resin composite sheet can be obtained, which includes a plurality of sheet layers in which a plurality of woven sheets are laminated together, and a cured product of a resin material serving as a base material.

[0036] As described above, in the manufacturing method disclosed herein, the first fiber material and the second fiber material maintain a woven state even after the curing step S6. This makes the fiber-resin composite sheet less susceptible to structural collapse and more tear-resistant than, for example, the technology of Patent Document 1, thereby increasing its strength. This allows for a relatively high level of both high strength and flexibility. Furthermore, it also becomes possible to use highly flexible resins while maintaining high strength, further improving flexibility.

[0037] In the manufacturing method of this embodiment, carbon nanotube fibers are used as the first fiber material in the preparation step. This effectively improves the thermal conductivity and electrical conductivity of the fiber-resin composite sheet in the first direction X (the extension direction of the first fiber material). Furthermore, it improves at least one of the hardness, strength, dimensional stability, and heat resistance of the fiber-resin composite sheet.

[0038] In the manufacturing method of this embodiment, in the preparing step, the second fiber material is made of a fiber different from that of the first fiber material, which allows the properties of the fiber-resin composite sheet to be suitably different between the first direction X (the extension direction of the first fiber material) and the second direction Y (the extension direction of the second fiber material).

[0039] In the manufacturing method of this embodiment, it is preferable to use aramid fiber as the second fiber material in the preparing step, which can improve at least one of hardness, strength, flexibility, and heat resistance of the fiber-resin composite sheet.

[0040] In the manufacturing method of this embodiment, in the laminating step, the woven sheets are laminated in multiple layers so that the stretching directions of the first fiber material are the same, thereby making it possible to suitably differentiate the properties (e.g., electrical conductivity or thermal conductivity) of the fiber-resin composite sheet between the first direction X (stretching direction of the first fiber material) and the second direction Y (stretching direction of the second fiber material).

[0041] The manufacturing method of this embodiment further includes a sewing step S4 after the laminating step in which the sheet layers are sewn together in the thickness direction with a sewing thread, thereby improving the unity of the sheet layers in the thickness direction and thereby increasing the strength and dimensional stability of the fiber-resin composite sheet in the thickness direction.

[0042] In the manufacturing method of this embodiment, at least one of the first fiber material and the second fiber material is used as the suture. If the first fiber material is a highly thermally conductive fiber (e.g., a fiber containing a carbon material), this increases the thermal conductivity in the thickness direction of the fiber-resin composite sheet, making it easier for thermal diffusion to occur within the fiber-resin composite sheet. Furthermore, if the second fiber material is a low-thermal-conductivity fiber (e.g., an organic fiber), this further increases the orientation of thermal conduction in the stretching direction (first direction X) of the first fiber material.

[0043] The manufacturing method of this embodiment further includes a cutting step S2 in which the woven sheet is cut to a predetermined size. For example, by performing this step before the lamination step S3, it is possible to prevent misalignment of the multiple sheet layers, thereby improving workability and dimensional stability. Furthermore, by performing this step before the impregnation step S5 described below, it is possible to thoroughly impregnate each sheet layer with the resin material.

[0044] <Fiber-resin composite sheet> The fiber-resin composite sheet disclosed herein includes a laminate formed by stacking a plurality of woven sheet layers in the thickness direction, and a cured product of a resin material impregnated into the laminate. Each sheet layer of the laminate is formed by crossing a first fiber material with a second fiber material that may be the same as or different from the first fiber material.

[0045] As described in the preparation step S1 above, the first fiber material preferably contains inorganic fibers, more preferably contains fibers containing a carbon material (e.g., carbon fibers or CNT fibers), and preferably contains CNT fibers. The first fiber material is more preferably made of inorganic fibers (95% or more by number are inorganic fibers), and even more preferably made of fibers containing a carbon material (e.g., carbon fibers or CNT fibers) (95% or more by number are fibers containing a carbon material). The second fiber material preferably contains fibers different from the first fiber material. When the first fiber material is a fiber containing a carbon material (e.g., carbon fibers or CNT fibers), the second fiber material is preferably a fiber other than the first fiber material. As described in the preparation step S1 above, the second fiber material preferably contains organic fibers, and more preferably contains aramid fibers. The second fiber material is more preferably made of organic fibers (95% or more by number are organic fibers), and even more preferably made of aramid fibers (95% or more by number are aramid fibers).

[0046] In some embodiments, the sheet layers of the laminate are preferably laminated so that the stretching direction (first direction X) of the first fiber material coincides with that of the second fiber material, as described in the lamination step S3 above. This allows the physical properties (e.g., electrical conductivity or thermal conductivity) to be suitably different between the stretching direction of the first fiber material and the stretching direction of the second fiber material.

[0047] In some embodiments, the sheet layers of the laminate are preferably sewn together with a sewing thread in the thickness direction (stacking direction of the sheet layers) perpendicular to the first direction X and the second direction Y, as described in the sewing step S4 above. This improves the integrity of the sheet layers, thereby increasing the strength and dimensional stability of the fiber-resin composite sheet in the thickness direction. The sewing thread is preferably at least one of a first fiber material (e.g., fiber containing a carbon material) and a second fiber material (e.g., aramid fiber), and more preferably the first fiber material (e.g., fiber containing a carbon material).

[0048] In some embodiments, the resin material serving as the base material is preferably a thermoplastic resin, and more preferably a silicone resin from the viewpoint of flexibility, etc. Furthermore, the heat resistance temperature of the resin material and the fiber-resin composite sheet is preferably 150°C or higher, more preferably 200°C or higher, for applications such as power semiconductors. The heat resistance temperature of the resin material and the fiber-resin composite sheet may be 500°C or lower.

[0049] As described above, the fiber-resin composite sheet disclosed herein includes a laminate formed by stacking multiple woven sheet layers in the thickness direction and a cured resin material impregnated into the laminate. This makes the fiber-resin composite sheet less susceptible to structural collapse and more resistant to tearing, thereby increasing its strength. This allows for a relatively high level of both high strength and flexibility. Furthermore, it also allows for the use of highly flexible resins while maintaining high strength, further improving flexibility.

[0050] In the fiber-resin composite sheet of this embodiment, the plurality of sheet layers are laminated in the thickness direction so that the stretching direction (first direction X) of the first fiber material coincides.

[0051] In the fiber resin composite sheet of this embodiment, the first fiber material contains carbon nanotube fibers.

[0052] In the fiber-resin composite sheet of this embodiment, the second fiber material contains fibers different from those of the first fiber material.

[0053] In the fiber-resin composite sheet of this embodiment, the second fiber material includes aramid fiber.

[0054] In the fiber-resin composite sheet of this embodiment, the plurality of sheet layers are sewn together in the thickness direction with a sewing thread.

[0055] In the fiber-resin composite sheet of this embodiment, the suture thread includes a first fiber material or a second fiber material.

[0056] <Applications of fiber-resin composite sheets> The fiber resin composite sheet disclosed herein can be suitably used, for example, as a thermally conductive sheet for transferring heat from a first member to a second member, a conductive sheet for transferring electricity from a first member to a second member, an electromagnetic wave shield for blocking electromagnetic waves from a first member to a second member, etc. In one example, the first member and the second member are electronic components for a semiconductor (e.g., a power semiconductor), and the fiber resin composite sheet disclosed herein can be incorporated into the power semiconductor together with the first member and the second member.

[0057] FIG. 3 is a plan view schematically illustrating a method of using a fiber-resin composite sheet according to one embodiment. In some embodiments, the fiber-resin composite sheet disclosed herein can be suitably used as a thermally conductive sheet interposed between a heat source and a heat exchanger (e.g., a heat sink) to conduct heat from the heat source to the heat exchanger. Because the fiber-resin composite sheet disclosed herein is highly flexible, it can flexibly change its shape to, for example, match the outer shape of the heat source and / or the heat exchanger. This improves adhesion to the heat source and / or the heat exchanger. In this embodiment, the fiber-resin composite sheet is preferably arranged so that the stretching direction (first direction X) of the first fiber material coincides with the heat transfer direction for conducting heat from the heat source to the heat exchanger. The fiber-resin composite sheet is arranged so that the stretching direction (second direction Y) of the second fiber material follows the outer shape of the heat source and the heat exchanger in a planar view. The XY plane of the fiber-resin composite sheet extends across a plane. However, in other embodiments, the fiber-resin composite sheet may be arranged so that the thickness direction (the stacking direction of multiple sheet layers) perpendicular to the first direction X and the second direction Y follows the outer shapes of the heat source and the heat exchanger.

[0058] Although the preferred embodiments of the present invention have been described above, the above-described embodiments are merely examples, and the present invention can be embodied in various other forms.

[0059] <Modification> For example, in the flowchart of Figure 1, the method for producing a fiber-resin composite sheet includes a preparation step S1, a cutting step S2, a lamination step S3, a stitching step S4, an impregnation step S5, and a curing step S6, in this order. That is, the steps are included in the order shown in Example 1 of Table 1 below. However, this is not limiting. For example, the order of the steps (step order 1 to 6) may be changed as appropriate, as shown in Examples 2 to 9 of Table 1 below.

[0060] [Table 1]

[0061] In a preferred embodiment, the impregnation step is followed by the lamination step and then the curing step, as shown in Examples 2, 8, and 9 in Table 1. For example, depending on the type of resin material, it may be difficult for the resin material to penetrate deep into the laminate once it has been formed into a laminate, but by following this order, the resin material can be thoroughly impregnated into each sheet layer of the laminate. [Explanation of symbols]

[0062] S1 Preparation process S2 cutting process S3 Lamination process S4 Suturing process S5 Impregnation process S6 curing process

Claims

1. a preparing step of preparing a woven sheet formed by crossing a first fiber material with a second fiber material that is the same as or different from the first fiber material; a lamination step of laminating a plurality of layers of the woven sheet in the thickness direction to obtain a laminate having a plurality of sheet layers; an impregnation step of impregnating the woven sheet with a resin material; a curing step of curing the impregnated resin material while the first fiber material and the second fiber material maintain the woven fabric state after the impregnation step; A method for producing a fiber-resin composite sheet, comprising:

2. In the preparing step, carbon nanotube fibers are used as the first fiber material. The method of claim 1.

3. In the preparing step, a fiber different from the first fiber material is used as the second fiber material. The method of claim 2.

4. In the preparing step, aramid fibers are used as the second fiber material. The method of claim 2.

5. In the laminating step, the woven sheet is laminated in a plurality of layers so that the stretching directions of the first fiber material are aligned. The method of any one of claims 1 to 4.

6. The method further includes a sewing step of sewing together the plurality of sheet layers with a sewing thread in the thickness direction after the laminating step. The method of any one of claims 1 to 4.

7. At least one of the first fiber material and the second fiber material is used as the suture. The method of claim 6.

8. Further comprising a cutting step of cutting the woven sheet to a predetermined size. The method of any one of claims 1 to 4.

9. After the impregnation step, the lamination step is carried out, and then the curing step is carried out. The method of any one of claims 1 to 4.

10. a laminate formed by laminating, in a thickness direction, a plurality of woven sheet layers each formed by crossing a first fiber material with a second fiber material that is the same as or different from the first fiber material; a cured product of the resin material impregnated into the laminate; A fiber-resin composite sheet comprising:

11. The plurality of sheet layers are stacked so that the stretching directions of the first fiber materials are aligned. The fiber-resin composite sheet according to claim 10.

12. the first fiber material comprises carbon nanotube fibers; The fiber-resin composite sheet according to claim 11.

13. the second fibrous material comprises fibers different from the first fibrous material; The fiber-resin composite sheet according to claim 12.

14. the second fibrous material comprises aramid fibers; The fiber-resin composite sheet according to claim 12.

15. The plurality of sheet layers are sewn together in the thickness direction with a suture. The fiber-resin composite sheet according to any one of claims 10 to 14.

16. the suture comprises the first fibrous material or the second fibrous material; The fiber-resin composite sheet according to claim 15.

17. It is interposed between the heat source and the heat exchanger, Used as a heat conduction sheet for conducting heat from the heat source to the heat exchanger. The fiber-resin composite sheet according to any one of claims 10 to 14.

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