Method for manufacturing prepreg for forming carbon fiber-reinforced plastic, and method for manufacturing carbon fiber-reinforced plastic

Abstract

To provide a method for manufacturing a prepreg for forming a thermosetting carbon fiber-reinforced plastic, which is excellent in storability, workability and mass productivity.SOLUTION: A method for manufacturing a prepreg for forming a carbon fiber-reinforced plastic containing a carbon fiber and an epoxy resin includes: an electro-deposition step S1 of applying a voltage using a carbon fiber material obtained by combining carbon fibers as a cathode and precipitating an electrolytic active epoxy resin on the surface of the carbon fiber, in a state in which the carbon fiber material is immersed in a cation electro-deposition coating obtained by dispersing the electrolytic active epoxy resin in water; and a heating dehydration step S2 of heating the carbon fiber material obtained by electro-deposition coating the cation electro-deposition coating at a temperature equal to or lower than 180°C, and removing moisture.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for producing a prepreg for forming a carbon fiber reinforced plastic, and a method for producing a carbon fiber reinforced plastic. [Background technology]

[0002] Carbon fiber reinforced plastics (CFRP), which are made by using carbon fiber as a reinforcement in a plastic base material, are lighter and stronger than metal materials such as iron and aluminum. For this reason, there are high expectations for CFRP as a material that can achieve both weight reduction and strength improvement in parts by using it as a material for parts in various industrial products, including automobiles.

[0003] CFRP can be divided into two types: thermoplastic CFRP, which uses a thermoplastic resin as the base plastic, and thermosetting CFRP, which uses a thermosetting resin such as epoxy resin as the base plastic. Thermoplastic CFRP retains the properties of thermoplastic resin, which softens when heated and hardens when cooled, so production methods with short takt times, such as hot pressing, can be used to mold thermoplastic CFRP into the desired shape of parts. Therefore, thermoplastic CFRP is easy to mold into the shape of the parts and components to be used, and can be provided as a material with excellent mass productivity for secondary processing.

[0004] Thermoplastic CFRP manufacturing methods include one method in which a laminate is made by sandwiching a thermoplastic resin film between bundled or woven carbon fiber material, and the entire prepreg laminate is pressurized and heated to impregnate the spaces between the carbon fibers with a heat-molten thermoplastic resin film and adhere it to the surface of the carbon fibers, and another method in which a carbon fiber laminate made by layering bundled or woven carbon fiber material is pressurized and impregnated with a heated and molten thermoplastic resin while being molded. Both methods utilize the property of thermoplastic resins, which soften and become fluid when heated above their melting point, in order to allow the resin impregnated between the carbon fibers to adhere uniformly to the carbon fiber surface.

[0005] However, if the thermoplastic resin does not penetrate the fine details of the carbon fiber material sufficiently, uniform adhesion to the surface of the carbon fiber is not achieved, resulting in the formation of voids and other defects. These voids become defects and significantly reduce the strength of the CFRP. Therefore, the production of thermoplastic CFRP not only requires heating to make the thermoplastic resin flowable, but also requires a long-term, high-pressure heating and pressurization process. This long-term heating and pressurization process requires large-scale equipment such as an autoclave, which increases costs and significantly reduces the productivity of thermoplastic CFRP.

[0006] On the other hand, thermosetting CFRP mainly uses epoxy resin, a thermosetting resin, and is highly reliable because it retains the excellent heat resistance, chemical resistance, and mechanical properties such as rigidity that epoxy resin has.It is expected to be an optimal material that can achieve both lightweight and high strength in parts and components of various industrial products.

[0007] One method for manufacturing thermosetting CFRP involves first mixing a low-molecular-weight thermosetting resin with a curing agent and additives to create a low-viscosity, highly fluid coating material. This coating material is then applied to a bundle or woven carbon fiber material to create a composite sheet called a prepreg. The resulting prepreg is then molded into the desired shape in a single layer or laminated state, while being heated to the curing temperature of the thermosetting resin. This method ensures that the coating material wets the carbon fiber surface, allowing it to penetrate between the carbon fibers and adhere uniformly to the surface. Therefore, unlike thermoplastic CFRP, thermosetting CFRP does not require the long heating and high-pressure processes required for impregnation and adhesion. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Patent No. 7162925 [Patent Document 2] Japanese Patent Application Publication No. 10-195349 [Non-patent literature]

[0009] [Non-Patent Document 1] Takao Saito: Color Materials, 72(3), 156(1999) Summary of the Invention [Problem to be solved by the invention]

[0010] However, the thermosetting coating materials used in thermosetting CFRP have a high curing reactivity, resulting in a short pot life for processing operations such as impregnation. Prepregs coated with thermosetting coating materials must be refrigerated or frozen for storage. This makes prepregs difficult to handle and work with. Furthermore, the cured molded products do not possess the same properties as thermoplastic CFRP, which soften when heated and harden when cooled. Therefore, molding thermosetting CFRP into the desired shape for the parts or components requires complex and difficult secondary processing steps, such as cutting, polishing, and assembly, resulting in long cycle times and poor mass production.

[0011] Therefore, Patent Document 1 discloses a configuration for producing a thermosetting CFRP without forming a prepreg by utilizing the electrical conductivity of a carbon fiber material. Specifically, Patent Document 1 discloses a configuration in which a carbon fiber material serving as a precursor for a thermosetting CFRP is first formed into a desired three-dimensional shape, the carbon fiber material is immersed in an electrodeposition paint and a voltage is applied to electrodeposit the surface of the carbon fiber, and then unreacted electrodeposition paint is removed from the carbon fiber material and the material is heated to a temperature equal to or higher than the curing temperature of the resin to cure the resin, thereby producing a thermosetting CFRP with a desired three-dimensional shape. Patent Document 1 also discloses another configuration in which a voltage is applied to a carbon fiber material immersed in an electrodeposition paint to electrodeposit the surface of the carbon fiber, and the material is then formed into a desired three-dimensional shape with unreacted electrodeposition paint remaining, and then the unreacted electrodeposition paint is removed from the carbon fiber material and the material is heated to a temperature equal to or higher than the curing temperature of the resin to cure the resin, thereby producing a thermosetting CFRP with a desired three-dimensional shape.

[0012] However, the configuration disclosed in Patent Document 1 does not use prepregs, so each time a thermosetting CFRP is produced, it is necessary to form a carbon fiber material into a desired three-dimensional shape, impregnate the carbon fiber material with an electrodeposition paint, apply a voltage, and heat it to the curing temperature of the electrodeposition paint. As such, a configuration that does not use prepregs is difficult to work with and has low mass productivity.

[0013] As other thermosetting electrodeposition paints, for example, Non-Patent Document 1 and Patent Document 2 disclose electrolytically activated electrodeposition paints.

[0014] The present invention has been made in view of the above background, and aims to provide a method for producing a prepreg for forming a thermosetting carbon fiber reinforced plastic, which has excellent storage stability, workability and mass productivity. [Means for solving the problem]

[0015] One aspect of the present invention is A method for producing a prepreg for forming a thermosetting carbon fiber reinforced plastic, comprising carbon fibers and an epoxy resin, an electrodeposition step in which a carbon fiber material formed by combining carbon fibers is immersed in a cationic electrodeposition paint in which an electrolytically activated epoxy resin is dispersed in water, and a voltage is applied using the carbon fiber material as a cathode to deposit the electrolytically activated epoxy resin on the surface of the carbon fiber; a heating and dehydration step of heating the carbon fiber material electrodeposited with the cationic electrodeposition paint at a temperature of 180°C or less to remove moisture; The present invention relates to a method for producing a prepreg for forming a thermosetting carbon fiber reinforced plastic, comprising the steps of:

[0016] In another aspect of the present invention, there is provided a molding process for deforming the prepreg for forming a carbon fiber reinforced plastic, which is manufactured by the manufacturing method of the prepreg for forming a thermosetting carbon fiber reinforced plastic according to the above-mentioned one aspect, along a molding die to form the prepreg into a target shape; a curing step of heating the prepreg for forming carbon fiber reinforced plastics molded into the target shape at a temperature of 180°C or higher to cure the electrolytically activated epoxy resin; The present invention relates to a method for producing a thermosetting carbon fiber reinforced plastic, comprising: [Effects of the Invention]

[0017] In the above-described method for producing a prepreg for forming a thermosetting carbon fiber reinforced plastic, the electrolytically activated epoxy resin has electrodeposition latency with respect to the curing reaction of the coating. Electrodeposition latency refers to a property of the coating that the curing reaction is initially latent and requires an electrodeposition process to become active. In other words, to initiate the curing reaction of the coating, it is essential to apply a voltage in advance in the electrodeposition process to cause an electrochemical reaction; the curing reaction does not proceed simply by heating without applying a voltage. Furthermore, the progress of the curing reaction after the electrodeposition process is slow below the curing temperature of the epoxy resin, and in particular, it hardly progresses at room temperature, and is also slow in the temperature range of 100 to 180°C.

[0018] In the manufacturing method of the one aspect described above, the carbon fiber material that has been electrodeposited in an electrodeposition step with a cationic electrodeposition paint obtained by dispersing an electrolytically activated epoxy resin in water is heated at a temperature of 180°C or less to remove moisture remaining in the carbon fiber material, thereby producing a prepreg. Because the curing reaction does not actively proceed at this heating temperature, the epoxy resin in the produced prepreg is in a semi-cured state, and the prepreg can be maintained in a semi-cured state at room temperature.

[0019] Therefore, the prepreg produced by the above-described manufacturing method does not require refrigeration or freezing during storage, as is the case with conventional prepregs, resulting in a longer pot life and improved workability. Furthermore, because the prepreg is in a semi-cured state at room temperature, it can be easily molded into the shape of parts and components to which thermosetting CFRP is to be applied. As a result, takt time can be shortened and mass productivity is high.

[0020] As described above, according to the above-described one aspect, it is possible to provide a method for producing a prepreg for forming a thermosetting carbon fiber reinforced plastic, which is excellent in storage stability, workability, and mass productivity.

[0021] According to the method for producing a thermosetting carbon fiber reinforced plastic of the other aspect, the prepreg for forming a thermosetting carbon fiber reinforced plastic produced by the production method of the one aspect can be easily molded into the shape of a desired part or component, thereby shortening the takt time and improving mass productivity. Furthermore, since the thermosetting carbon fiber reinforced plastic uses an epoxy resin as the thermosetting resin, it has excellent heat resistance, chemical resistance, and mechanical properties such as rigidity, making it highly reliable and able to contribute to achieving both weight reduction and high strength in parts and components of various industrial products. [Brief explanation of the drawings]

[0022] [Figure 1] FIG. 1 is a flow diagram showing a method for producing a prepreg for forming a thermosetting carbon fiber reinforced plastic in the first embodiment. [Figure 2] FIG. 2A is a conceptual perspective view of carbon fiber and prepreg in the first embodiment, and FIG. 2B is a conceptual perspective view illustrating a prepreg joining step. [Figure 3] FIG. 2 is a conceptual diagram illustrating an electrodeposition step in the first embodiment. [Figure 4] 1 is a flow diagram showing a method for producing a thermosetting carbon fiber reinforced plastic in the first embodiment. [Figure 5] 1 is a conceptual perspective view of a molded product of thermosetting carbon fiber reinforced plastic in the first embodiment. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0023] In the above-described one aspect of the method for producing a prepreg for forming a thermosetting carbon fiber reinforced plastic, the heating temperature in the thermal dehydration step is preferably 100° C. or higher and 180° C. or lower. In this case, the produced prepreg can be easily brought to a semi-cured state early without being completely cured.

[0024] In the method for producing a prepreg for forming a thermosetting carbon fiber reinforced plastic according to the above aspect, the electrolytically activated epoxy resin is preferably a novolac phenol polyepoxy resin. In this case, the thermosetting carbon fiber reinforced plastic formed using the produced prepreg has superior heat resistance, chemical resistance, and mechanical properties such as rigidity, as well as light weight, thereby further improving reliability.

[0025] Furthermore, the method for producing a prepreg for forming a thermosetting carbon fiber reinforced plastic according to the above-mentioned embodiment can include, after the heating and dehydration step, a joining step of laminating a plurality of the sheet-like carbon fiber materials electrodeposited with the cationic electrodeposition paint, heating the laminate at a temperature of 180° C. or less, and rolling the laminate to join the carbon fiber materials to each other. In this case, rolling can form a prepreg having a smooth surface and closely packed carbon fibers.

[0026] In the method for producing a thermosetting carbon fiber reinforced plastic according to the other aspect described above, the molding step and the curing step can be carried out in parallel, thereby shortening the time required to produce the thermosetting carbon fiber reinforced plastic.

[0027] In the method for producing a thermosetting carbon fiber reinforced plastic according to the other aspect described above, the heating temperature in the curing step is preferably 180° C. or higher and 300° C. or lower. In this case, the prepreg in a semi-cured state can be cured early, the takt time can be further shortened, and mass productivity can be further improved.

[0028] (Embodiment 1) 1. Prepreg for thermosetting carbon fiber reinforced plastics A prepreg for forming a thermosetting carbon fiber reinforced plastic (hereinafter, in this specification, simply referred to as a "prepreg") is a composite of carbon fiber and a thermosetting resin for forming a thermosetting carbon fiber reinforced plastic, and is in a state where the carbon fiber material is pre-impregnated with the thermosetting resin.

[0029] 2. Carbon fiber material Carbon fiber materials are formed by combining carbon fibers in a bundle or woven form. The structure of the carbon fiber material is not limited, and examples include a flat carbon fiber sheet and a bundle of carbon fibers. The carbon fiber sheet can be one in which multiple carbon fibers are woven in perpendicular directions. The weaving pattern is not limited, and known weaves such as plain weave and twill weave can be used. In addition, carbon fiber sheets in which carbon fibers are arranged not only linearly but also curvedly may be used. The average fiber diameter of each carbon fiber is preferably within the range of 0.001 to 50 μm from the viewpoint of sufficient precipitation of the epoxy resin described below. In this embodiment, a plain-woven carbon fiber sheet 10 shown in FIG. 1(a) is used as the carbon fiber material. The longitudinal and lateral dimensions of the carbon fiber sheet 10 are not limited, and the thickness of the carbon fiber sheet 10 is also not limited.

[0030] 3. Cationic electrodeposition paint The cationic electrodeposition paint used in the manufacturing method of thermosetting carbon fiber reinforced plastic is an electrolytically activated epoxy resin dispersed in water. Hereinafter, this cationic electrodeposition paint will also be referred to as "electrolytically activated electrodeposition paint." The electrolytically activated epoxy resin is composed of an epoxy resin that is electrolytically activated by an electrode reaction. More specifically, the electrolytically activated epoxy resin forms an epoxy resin coating by applying a voltage in the electrodeposition process, and the electrode reaction caused by the voltage application generates activated chemical species in the coating, which promote the progress of the curing reaction of the coating. Furthermore, the progress of the curing reaction after voltage application is slow below the curing temperature of the epoxy resin, and in particular, it hardly progresses at room temperature, and is also slow in the temperature range of 100 to 180°C.

[0031] The epoxy resin used in such electrolytically activated electrodeposition paints is a resin composition containing sulfonium and propargyl groups in addition to the epoxy groups that constitute the epoxy resin. The resin composition of the electrolytically activated epoxy resin may, but does not necessarily, contain both sulfonium and propargyl groups in one molecule containing an epoxy group. For example, it may contain only either a sulfonium or propargyl group in one molecule. In this case, the resin composition as a whole contains these two types of functional groups. That is, the resin composition may consist of a resin containing sulfonium and propargyl groups, or a mixture of a resin containing only sulfonium groups and a resin containing only propargyl groups, or a mixture of all of these.

[0032] The epoxy resin that forms the backbone of the electrolytically activated epoxy resin is preferably one having at least two epoxy groups per molecule, and specific examples include epibis-type epoxy resins, those chain-extended with diols, dicarboxylic acids, diamines, etc.; epoxidized polybutadienes; novolac phenol-type polyepoxy resins; novolac cresol-type polyepoxy resins; polyglycidyl acrylate; polyglycidyl ethers of aliphatic polyols or polyether polyols; and polyglycidyl esters of polybasic carboxylic acids. Of these, novolac phenol-type polyepoxy resins, novolac cresol-type polyepoxy resins, and polyglycidyl acrylate are preferred because they can be easily multifunctionalized to enhance curability.

[0033] Examples of electrolytically activated electrodeposition paints containing such electrolytically activated epoxy resins include Insulead (registered trademark) 1000 and Insulead (registered trademark) 3000 manufactured by Nippon Paint Industrial Coatings Co., Ltd. Note that Insulead 1000 and Insulead 3000 contain phenolic resin (novolac resin) as a polymer compound, and can impart insulating properties and heat resistance by precipitating the epoxy resin. In this embodiment, Insulead 3000 is used as the electrolytically activated electrodeposition paint.

[0034] 4. Manufacturing method of prepreg for forming thermosetting carbon fiber reinforced plastic As shown in FIG. 2, the method for producing a prepreg for forming a thermosetting carbon fiber reinforced plastic according to the first embodiment includes an electrodeposition step S1, a heat dehydration step S2, and a joining step S3.

[0035] 4-1.Electrodeposition process In the electrodeposition step S1 shown in Fig. 2, first, in step S11, a carbon fiber material is impregnated with an electrolytically activated electrodeposition paint. In the present embodiment 1, as shown in Fig. 3, a carbon fiber material 10 is immersed in an electrolytically activated electrodeposition paint 20 of a predetermined concentration stored in a reaction tank 30. As a result, the electrolytically activated electrodeposition paint 20 penetrates into the spaces between the carbon fibers constituting the carbon fiber material 10. An electrode 31 is also immersed in the reaction tank 30. The configuration of the electrode 31 is not limited, and the material may be any conductive material, for example, stainless steel, aluminum, carbon, etc.

[0036] Thereafter, in step S12, a voltage is applied to the carbon fiber material 10. In the first embodiment, as shown in Fig. 3, the carbon fiber material 10 in the reaction tank 30 and an electrode 31 are electrically connected via a power supply 32, and the output of the power supply 32 is controlled by a controller 33 to apply a voltage from the power supply 32 so that the carbon fiber material 10 serves as the cathode. As a result, the epoxy resin present as a polymer compound colloid in the electrolytically activated electrodeposition paint 20 adheres to the surface of the carbon fiber material 10 by electrophoresis, and is insolubilized and precipitated (electrodeposited) by an electrode reaction.

[0037] The voltage and current applied to the carbon fiber material are not particularly limited and can be appropriately selected depending on the type of electrolytically activated electrodeposition paint. In particular, the applied voltage is preferably 90 to 500 V, more preferably 100 to 300 V, from the viewpoint of more sufficiently depositing the epoxy resin on each carbon fiber while further suppressing the electrolysis of water. The applied current depends on the size, thickness, etc. of the carbon fiber material, but is preferably 0.01 to 1.0 A, more preferably 0.05 to 0.5 A, from the viewpoint of more sufficiently depositing the epoxy resin on each carbon fiber while further suppressing the electrolysis of water.

[0038] The voltage application time is not particularly limited and can be appropriately selected depending on the type of electrolytically activated electrodeposition coating material. In particular, from the viewpoint of more sufficiently depositing the epoxy resin on each carbon fiber while further suppressing the electrolysis of water, the voltage application time is preferably 1 to 300 minutes, more preferably 5 to 120 minutes.

[0039] 4-2. Heating dehydration process In the thermal dehydration step S2 shown in FIG. 1, the carbon fiber material after the electrodeposition step S1 is heated at a temperature of 180°C or less. This removes moisture derived from the electrolytically activated electrodeposition paint adhering to the carbon fiber material. The heating temperature in the thermal dehydration step S2 is 180°C or less, more preferably in the range of 100 to 180°C. By setting the heating temperature in the range of 100 to 180°C, moisture can be removed quickly while suppressing resin curing in the carbon fiber material after the electrodeposition step S1. The heating time in the thermal dehydration step S2 is not limited as long as it is a time that allows moisture to be sufficiently removed. Once the moisture has been sufficiently removed, a prepreg for forming a thermosetting carbon fiber reinforced plastic is completed. The prepreg has a shape that reflects the shape of the carbon fiber material, and in this embodiment, it has the same shape as the carbon fiber sheet 10 shown in FIG. 2.

[0040] In the thermal dehydration step S2, as described above, the heating temperature is 180°C or less, so the curing of the electrolytically activated epoxy resin does not actively proceed, and the completed prepreg is in a semi-cured state. As described above, the curing reaction of the electrolytically activated epoxy resin after the electrodeposition step S1 hardly progresses at room temperature, so the completed prepreg 10a can be stored in a semi-cured state at room temperature.

[0041] 4-3.Joining process In this embodiment 1, the heating and dehydration step S2 is followed by the bonding step S3 shown in Fig. 1. In the bonding step S3, as shown in Fig. 2(b), a plurality of completed prepregs are stacked, heated at a temperature of 180°C or less, and rolled to be pressed in the direction indicated by arrow P and bonded together. The heating temperature in the bonding step S3 can be the same as the heating temperature in the heating and dehydration step S2. There is no limitation on the number of prepregs 10a to be stacked, and any desired number can be used.

[0042] 5. Manufacturing method of thermosetting carbon fiber reinforced plastics Next, a detailed description will be given of the method for producing a thermosetting carbon fiber reinforced plastic according to the present embodiment 1. The method for producing a thermosetting carbon fiber reinforced plastic includes a molding step S4 and a curing step S5.

[0043] 5-1. Molding process In the molding step S4 shown in Fig. 4, the prepreg 10a for forming a thermosetting carbon fiber reinforced plastic is deformed along a molding die and molded into a target shape. In this embodiment, a plurality of prepregs 10a for forming a thermosetting carbon fiber reinforced plastic are set in a molding die (not shown) and molded into the channel shape shown in Fig. 5.

[0044] 5-2.Curing process After the molding step S4, a curing step S5 shown in Fig. 4 is performed. In the curing step S5, the prepreg 10a for forming a thermosetting carbon fiber reinforced plastic is heated at a temperature of 180°C or higher to cure the electrolytically activated epoxy resin. The heating temperature in the curing step S5 can be 180°C or higher and 300°C or lower. This makes it possible to obtain a molded product of the thermosetting carbon fiber reinforced plastic 100 (see Fig. 5) having the target shape molded in the molding step S4.

[0045] The molding step S4 and the curing step S5 may be performed in parallel. That is, the prepreg 10a for forming a thermosetting carbon fiber reinforced plastic may be deformed along the molding die to form a target shape, while the electrolytically activated epoxy resin is cured by heating at a temperature of 180°C or higher.

[0046] 6. Action and Effects The effects of the method for producing a prepreg for forming a thermosetting carbon fiber reinforced plastic according to the first embodiment will be described below. According to the method for producing a prepreg for forming a thermosetting carbon fiber reinforced plastic of this embodiment 1, a carbon fiber material that has been electrodeposited in an electrodeposition step with a cationic electrodeposition paint made by dispersing an electrolytically activated epoxy resin in water is heated at a temperature of 180°C or less to remove moisture remaining in the carbon fiber material, thereby producing a prepreg 10a. Because the curing reaction does not actively proceed at this heating temperature, the epoxy resin in the produced prepreg 10a is in a semi-cured state, and the prepreg 10a can be maintained in a semi-cured state at room temperature.

[0047] Therefore, unlike conventional prepregs, the prepreg 10a does not require refrigeration or freezing during storage, resulting in a longer pot life and improved workability. Furthermore, because the prepreg 10a is in a semi-cured state at room temperature, it can be easily molded into the shape of parts and components to which the thermosetting CFRP is to be applied. As a result, takt time can be shortened and mass productivity is high.

[0048] In the first embodiment, the heating temperature in the thermal dehydration step S2 is 100° C. or higher and 180° C. or lower. This allows the prepreg 10a to be produced to be brought into a semi-cured state early on, without being completely cured.

[0049] In addition, in this embodiment 1, the electrolytically activated epoxy resin is a specially modified novolac epoxy resin, which allows the thermosetting carbon fiber reinforced plastic 100 formed using the produced prepreg 10a to have even better heat resistance, chemical resistance, and mechanical properties such as rigidity, as well as light weight, thereby further improving reliability.

[0050] Furthermore, in this embodiment 1, after the heating and dehydration step S2, a joining step S3 is included in which a plurality of sheet-shaped carbon fiber materials 10 electrodeposited with cationic electrodeposition paint are stacked, heated at a temperature of 180°C or less, and rolled to join the carbon fiber materials to each other. As a result, the surface of the prepreg 10a is smooth and the carbon fibers are closely packed by the rolling.

[0051] As described above, according to the first embodiment, it is possible to provide a method for producing the prepreg 10a for forming a thermosetting carbon fiber reinforced plastic, which is excellent in storage stability, workability and mass productivity.

[0052] The method for producing a thermosetting carbon fiber reinforced plastic according to the first embodiment includes a molding step S4 in which the prepreg 10a produced by the method for producing a prepreg for forming a carbon fiber reinforced plastic is deformed along a molding die to form a target shape, and a curing step S5 in which the prepreg 10a is heated to a temperature of 180°C or higher to cure the electrolytically activated epoxy resin. This allows the prepreg 10a for forming a thermosetting carbon fiber reinforced plastic according to the first embodiment to be easily molded into the shape of a desired part or component, thereby shortening takt time and improving mass productivity. Furthermore, because the thermosetting carbon fiber reinforced plastic uses an epoxy resin as the thermosetting resin, it has excellent heat resistance, chemical resistance, rigidity, and other mechanical properties, making it highly reliable and contributing to achieving both weight reduction and high strength in parts and components of various industrial products.

[0053] Furthermore, in the present embodiment 1, the molding step S4 and the curing step S5 can be carried out in parallel, which can shorten the time required to produce the thermosetting carbon fiber reinforced plastic.

[0054] Furthermore, in the method for producing a thermosetting carbon fiber reinforced plastic according to the first embodiment, the heating temperature in the curing step S5 is 180° C. or higher and 300° C. or lower. This allows the prepreg 10a, which is in a semi-cured state, to be cured early, further shortening the takt time and further improving mass productivity.

[0055] According to the method for producing a thermosetting carbon fiber reinforced plastic of the other aspect, the prepreg for forming a thermosetting carbon fiber reinforced plastic produced by the production method of the one aspect can be easily molded into the shape of a desired part or component, thereby shortening the takt time and improving mass productivity. Furthermore, since the thermosetting carbon fiber reinforced plastic uses an epoxy resin as the thermosetting resin, it has excellent heat resistance, chemical resistance, and mechanical properties such as rigidity, making it highly reliable and able to contribute to achieving both weight reduction and high strength in parts and components of various industrial products.

[0056] As described above, according to the first embodiment, it is possible to provide a thermosetting carbon fiber reinforced plastic that can contribute to achieving both weight reduction and high strength.

[0057] The present invention is not limited to the above-described embodiments, and can be applied to various embodiments within the scope of the present invention. [Explanation of symbols]

[0058] 10 Carbon fiber materials 10a Prepreg for thermosetting carbon fiber reinforced plastic molding 100 Thermosetting carbon fiber reinforced plastic 20 Electrolytically activated electrodeposition paint (cationic electrodeposition paint) 30 Reaction Tank 31 electrode 32 Power supply 33 Controller

Claims

1. A method for producing a prepreg for forming a carbon fiber reinforced plastic, comprising carbon fibers and an epoxy resin, an electrodeposition step in which a carbon fiber material formed by combining carbon fibers is immersed in a cationic electrodeposition paint in which an electrolytically activated epoxy resin is dispersed in water, and a voltage is applied using the carbon fiber material as a cathode to deposit the electrolytically activated epoxy resin on the surface of the carbon fiber; a heating and dehydration step of heating the carbon fiber material electrodeposited with the cationic electrodeposition paint at a temperature of 180°C or less to remove moisture; A method for producing a prepreg for forming a thermosetting carbon fiber reinforced plastic, comprising:

2. 2. The method for producing a prepreg for forming a thermosetting carbon fiber reinforced plastic according to claim 1, wherein the heating temperature in the thermal dehydration step is 100°C or higher and 180°C or lower.

3. 3. The method for producing a prepreg for forming a thermosetting carbon fiber reinforced plastic according to claim 1, wherein the electrolytically activated epoxy resin is a novolac phenol polyepoxy resin.

4. 3. The method for producing a prepreg for forming a thermosetting carbon fiber reinforced plastic according to claim 1, further comprising, after the heating and dehydration step, a joining step of laminating a plurality of the sheet-like carbon fiber materials electrodeposited with the cationic electrodeposition paint, heating the laminate at a temperature of 180°C or less, and rolling the laminate to join the carbon fiber materials to each other.

5. a molding step of deforming the prepreg for forming carbon fiber reinforced plastics manufactured by the method for manufacturing a prepreg for forming carbon fiber reinforced plastics according to claim 1 or 2 along a molding die to form the prepreg into a target shape; a curing step of heating the prepreg for forming a carbon fiber reinforced plastic at a temperature of 180°C or higher to cure the electrolytically activated epoxy resin; A method for producing a thermosetting carbon fiber reinforced plastic, comprising:

6. The method for producing a thermosetting carbon fiber reinforced plastic according to claim 5, wherein the molding step and the curing step are carried out in parallel.

7. The method for producing a thermosetting carbon fiber reinforced plastic according to claim 5, wherein the heating temperature in the curing step is 180°C or higher and 300°C or lower.

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