Resin composition, prepreg, and method for producing a prepreg

Abstract

To provide a prepreg which is tack free and has good shape retention property.SOLUTION: A resin composition is composed of a first agent and a second agent, and is coated onto a reinforcement fiber base material for producing a prepreg, wherein the first agent contains (A) a solid epoxy resin having film-forming property, (B) a liquid epoxy resin, (C) a latent curing agent for an epoxy resin, (D) a compound having one (meth) acryloyloxy group and one or more epoxy groups in one molecule, and (E) an organic peroxide, and the second agent contains (F) a reducer.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a resin composition used for producing a prepreg, a prepreg, and a method for producing a prepreg.

Background Art

[0002] Since fiber reinforced resin materials are lightweight and have excellent strength, they are widely used in various fields such as sports goods, medical materials, aerospace materials, automotive materials, and building materials. Molded products made of fiber reinforced resin materials are usually formed by laminating a molding base material called a prepreg, which is obtained by impregnating a reinforcing fiber base material with a matrix resin, and applying pressure and heat to shape the matrix resin.

[0003] As prepregs, sheet prepregs, prepreg tapes, and tow prepregs are known. As sheet prepregs, there are sheet-shaped molding base materials (reinforcing fiber fabrics) obtained by impregnating woven or knitted fabrics as reinforcing fiber base materials with a matrix resin, and sheet-shaped molding base materials (UD materials) obtained by impregnating reinforcing fiber base materials composed of a plurality of reinforcing fibers arranged in parallel in one direction with a matrix resin. A prepreg tape is a molding base material obtained by cutting a sheet prepreg into a predetermined width. A tow prepreg is a molding base material obtained by impregnating a reinforcing fiber bundle composed of a plurality of reinforcing fibers with a matrix resin.

[0004] Patent Document 1 describes a method for producing a prepreg sheet. Here, a resin film obtained by applying an epoxy resin on a release paper and a carbon fiber sheet are laminated, and the carbon fiber sheet is impregnated with the epoxy resin. Further, Patent Document 2 describes a method for producing a tow prepreg. Here, a reinforcing fiber bundle is conveyed along a grooved roller having an epoxy resin supplied to its circumferential surface, and the reinforcing fiber bundle coated with the epoxy resin is pressed against a roller having a U-groove formed therein, so that the reinforcing fiber bundle is impregnated with the epoxy resin inside.

Prior Art Documents

Patent Documents

[0005] [Patent Document 1] Japanese Patent Publication No. 2013-108058 [Patent Document 2] Japanese Patent Publication No. 2003-266551 [Overview of the project] [Problems that the invention aims to solve]

[0006] Incidentally, there are cases where the manufacturing of the molding substrate and the shaping of the molded product are not carried out in the same facility, but rather prepregs that have only been impregnated with matrix resin are brought to the molding facility for shaping and solidification. However, conventionally known resin compositions have high tackiness, so winding and unwinding without release paper are not good. In addition, because the restraining force of the reinforcing fibers by the resin is weak, the shape of the prepreg changes during molding, or the fibers slip and the laminated shape of the prepreg collapses. As a result, problems such as reduced workability and reduced quality of molded products occur.

[0007] There is a demand for a prepreg that is tack-free and has good shape retention. [Means for solving the problem]

[0008] To solve the above problems, the present invention provides a resin composition comprising a first agent and a second agent, which is applied to a reinforcing fiber substrate for the production of a prepreg, wherein the first agent contains (A) a film-forming solid epoxy resin, (B) a liquid epoxy resin, (C) a latent curing agent for epoxy resins, (D) a compound having one (meth)acryloyloxy group and one or more epoxy groups in one molecule, and (E) an organic peroxide, and the second agent contains (F) a reducing agent.

[0009] At room temperature, polymerization reactions between (A) film-forming solid epoxy resin and (B) liquid epoxy resin do not occur due to (C) latent curing agents for epoxy resins. However, because (A) film-forming solid epoxy resin has film-forming ability, the fluidity of the entire resin composition is lost and it becomes solid, even in the presence of (B) liquid epoxy resin. Furthermore, (D) compounds having one (meth)acryloyloxy group and one or more epoxy groups in one molecule act as a solvent for (A) film-forming solid epoxy resin, and also undergo REDOX polymerization by the action of (E) organic peroxides and (F) reducing agents, losing their solvent function.

[0010] Therefore, in prepregs where a resin composition is applied to a reinforcing fiber substrate, the REDOX reaction of the resin composition proceeds. The surface of the prepreg becomes tack-free, resulting in good winding and unwinding properties even without release paper. It is easy to handle and has good storage properties. In addition, the polymerized resin composition restrains the reinforcing fibers of the reinforcing fiber substrate. This improves the shape retention of the prepreg and enhances workability at the molding site.

[0011] (B) The liquid epoxy resin can be mixed with (A) the film-forming solid epoxy resin to achieve a delicate balance of fluidity, and the entire resin composition can be moderately refluidified when heated. Furthermore, since component (D) is monofunctional, having one (meth)acryloyloxy group per molecule, it becomes a linear polymer through REDOX polymerization.

[0012] Therefore, although the overall fluidity of the resin composition is lost and it becomes solid, it becomes fluid again upon heating, and does not easily hinder the fluid deformation and fusion of the entire resin composition. On the other hand, when the latent curing agent for epoxy resin (C) is heated to the curing temperature, it reacts with the epoxy groups of the film-forming solid epoxy resin (A) and the liquid epoxy resin (B), causing the entire resin composition to thermally cure. In addition, heating causes the organic peroxide (E) to decompose and generate radicals, which act as initiators for the radical polymerization of the (meth)acryloyloxy groups of component (D). Since the linear polymer formed by the REDOX polymerization of component (D) contains one or more epoxy groups, at the temperature at which the latent curing agent for epoxy resin (C) thermally cures, component (D) reacts with component (C) in the same way as components (A) and (B), and is ultimately incorporated into the same molecular network.

[0013] Therefore, when heated to the curing temperature of the latent curing agent for epoxy resin (C), polymerization reactions proceed within the prepreg, which is a reinforced fiber substrate coated with the resin composition, and it heat-cures. This allows for the molding of molded products with superior strength. The quality of the molded products is improved.

[0014] In the above configuration, it is preferable that the first agent further contains (G) a photoradical initiator. (G) The photoradical initiator is a compound that generates radicals upon UV irradiation, causing radical polymerization of the (meth)acryloyloxy group of component (D). The REDOX polymerization reaction of component (D) by components (E) and (F) takes a relatively long time, but by irradiating the resin composition containing the photoradical initiator (G) with UV light, the polymerization reaction of component (D) proceeds more quickly from the surface of the prepreg. This allows the polymerization reaction in the prepreg coated with the resin composition to proceed more quickly. For example, when manufacturing prepregs, if the resin composition is applied, impregnated, and wound up while the reinforcing fiber substrate is being transported, it becomes possible to transport it at high speed. This can improve the production efficiency of prepregs.

[0015] To solve the above problems, the prepreg of the present invention comprises the resin composition and a reinforcing fiber substrate. According to the above configuration, a tack-free prepreg with good shape retention can be obtained.

[0016] In order to solve the above problems, a method for manufacturing a prepreg according to the present invention is a method for manufacturing a prepreg used for molding a molded product by impregnating a reinforcing fiber base material with the resin composition and laminating a plurality of layers to thermally cure the resin composition. The method includes a conveying step of conveying the reinforcing fiber base material along a roller, a first coating step of applying the first agent to at least one surface of the reinforcing fiber base material to form a first coated body, a second coating step of applying the second agent to the surface of the first coated body where the first agent is applied to form a coated body, and a winding step of winding the coated body around a winding roller. The first coating step conveys the reinforcing fiber base material along an oiling roller to which the resin composition is supplied on its peripheral surface.

[0017] According to the above configuration, the resin composition is applied and impregnated in the coated body that has undergone the first coating step and the second coating step. Therefore, it is possible to manufacture a prepreg in which the resin composition is applied and impregnated while being conveyed along the roller. It is possible to efficiently manufacture a prepreg with a tack-free surface and good shape retention.

[0018] In the above configuration, it is preferable that the first coating step further includes a photocuring step of applying the first agent containing a (G) photo radical initiator and irradiating both surfaces of the coated body with UV light.

[0019] According to the above configuration, it is possible to accelerate the polymerization reaction of a compound (D) having one (meth)acryloyloxy group and one or more epoxy groups in one molecule. It is possible to manufacture a prepreg with a tack-free surface and good shape retention at high speed.

Effects of the Invention

[0020] According to the present invention, a tack-free prepreg with good shape retention can be obtained.

Brief Description of the Drawings

[0021] [Figure 1]This is a diagram for explaining the manufacturing method of the prepreg of the present embodiment. [Figure 2] This is a diagram for explaining an example in which the shape retention of a prepreg coated and impregnated with a resin composition was evaluated.

Mode for Carrying Out the Invention

[0022] Hereinafter, a resin composition embodying the present invention and a manufacturing method for manufacturing a prepreg by coating and impregnating the resin composition will be described. <Regarding the resin composition> First, the resin composition will be described.

[0023] The resin composition to be coated and impregnated on the reinforcing fiber base material contains (A) a solid epoxy resin having film-forming properties, (B) a liquid epoxy resin, (C) a latent curing agent for epoxy resin, (D) a compound having one (meth)acryloyloxy group and one or more epoxy groups in one molecule, (E) an organic peroxide, (F) a reducing agent, and (G) a photo radical initiator. Hereinafter, the (A) solid epoxy resin having film-forming properties may be simply referred to as (A) solid epoxy resin. Also, the (C) latent curing agent for epoxy resin may be simply referred to as (C) latent curing agent. Further, the (D) compound having one (meth)acryloyloxy group and one or more epoxy groups in one molecule may be simply referred to as (D) monofunctional (meth)acryloyloxy group compound.

[0024] The resin composition of the present embodiment is a two-component mixed type composed of a first agent and a second agent, and is mixed immediately before coating on the reinforcing fiber base material. The first agent contains (A) solid epoxy resin, (B) liquid epoxy resin, (C) latent curing agent, (D) monofunctional (meth)acryloyloxy group compound, (E) organic peroxide, and (G) photo radical initiator. The second agent contains (F) reducing agent.

[0025] (A) Solid epoxy resin is the main component of the resin composition and has film-forming ability. (A) Solid epoxy resin can still cause the entire resin composition to lose its fluidity even in the presence of (B) liquid epoxy resin. (B) Liquid epoxy resin is an ingredient used to adjust the film-forming ability, surface tack, adhesion, and curability of (A) solid epoxy resin. (B) Liquid epoxy resin, when mixed with (A) solid epoxy resin, balances the fluidity in a delicate way and moderately re-fluidizes the entire resin composition when heated. (C) Latent curing agent is an ingredient used to cure (A) solid epoxy resin and (B) liquid epoxy resin. When heated to the curing temperature, it reacts with the epoxy groups of (A) solid epoxy resin and (B) liquid epoxy resin to cure the entire resin composition. (D) The monofunctional (meth)acryloyloxy compound acts as a solvent for (A) solid epoxy resin and undergoes REDOX polymerization by the action of (E) organic peroxide and (F) reducing agent upon mixing of the first and second agents. Furthermore, (D) the monofunctional (meth)acryloyloxy compound undergoes photoradical polymerization by (G) photoradical initiator.

[0026] The following explains each component. <(A) Regarding solid epoxy resin> (A) The solid epoxy resin is an epoxy resin having a relatively large number-average molecular weight. (A) The number-average molecular weight of the solid epoxy resin is preferably 600 to 20000, and more preferably 900 to 6000. (A) The solid epoxy resin is an epoxy resin that is solid at a temperature of 20°C. (A) The softening point of the solid epoxy resin is preferably 50 to 200°C, and more preferably 60 to 150°C.

[0027] (A) Examples of solid epoxy resins include Epicote 1001 (number average molecular weight (MW) 900, epoxy equivalent 475 g / eq, softening point 64°C), Epicote 1002 (MW 1060, epoxy equivalent 650 g / eq, softening point 78°C), Epicote 1003 (epoxy equivalent 720 g / eq, softening point 89°C), Epicote 1055 (MW 1350, epoxy equivalent 850 g / eq, Examples include Epicote 1004 (MW1600, epoxy equivalent 925 g / eq, softening point 97°C), Epicote 1007 (MW2900, epoxy equivalent 1975 g / eq, softening point 128°C), Epicote 1009 (MW3750, epoxy equivalent 2850 g / eq, softening point 144°C), and Epicote 1010 (MW5500, epoxy equivalent 4000 g / eq). These can be used individually or in combination of two or more types.

[0028] (A) The amount of solid epoxy resin added is preferably 10 to 50 parts by weight, and more preferably 20 to 40 parts by weight, when the total amount of components (A) to (G) in the resin composition is 100 parts by weight.

[0029] <(B) Regarding liquid epoxy resin> (B) Liquid epoxy resin is a component used to adjust the film-forming ability, surface tack, adhesion, and curing properties of (A) solid epoxy resin. The term "liquid" in (B) liquid epoxy resin is used to distinguish it from "solid" in (A) solid epoxy resin. It does not need to be solid at 20°C, and can be liquid to paste-like in consistency.

[0030] (B) Liquid epoxy resin is an epoxy resin with a smaller number-average molecular weight than solid epoxy resin. (B) The number-average molecular weight of liquid epoxy resin is preferably 100 to 3000, and more preferably 200 to 1500. (A) Solid epoxy resin alone generally has a low epoxy group content and insufficient curability. (B) Liquid epoxy resin has a glycidyl ether group derived from a phenolic OH group, and is preferably 300 g / eq or less in epoxy equivalent, in order to compensate for this.

[0031] (B) Examples of liquid epoxy resins include liquid bisphenol A type epoxy resin (bis(4-hydroxyphenyl)propane diglycidyl ether, etc.), liquid bisphenol F type epoxy resin, liquid phenol novolac type epoxy resin, liquid bisphenol AD ​​type epoxy resin, liquid naphthalene type epoxy resin (dihydroxynaphthalene diglycidyl ether, etc.), liquid glycidyl ester type epoxy resin (phthalate diglycidyl ester, etc.), liquid glycidyl ether type epoxy resin (catechol diglycidyl ether, resorcinol diglycidyl ether, mono-tert-butylhydroquinone diglycidyl ether, etc.), liquid glycidylamine type epoxy resin, liquid heterocyclic epoxy resin, liquid diarylsulfone type epoxy resin, and modified liquids thereof. These may be used individually or in combination of two or more types.

[0032] (B) The amount of liquid epoxy resin added is preferably 10 to 50 parts by weight, and more preferably 20 to 40 parts by weight, when the total amount of components (A) to (G) in the resin composition is 100 parts by weight. Furthermore, the ratio of solid epoxy resin (A) to liquid epoxy resin (B) is preferably in the range of 1:2 to 2:1.

[0033] <(C) Regarding latent curing agents> (C) The latent curing agent is a component that cures (A) solid epoxy resin and (B) liquid epoxy resin. When heated to the curing temperature, it reacts with the epoxy groups of (A) solid epoxy resin and (B) liquid epoxy resin, curing the entire resin composition. However, it does not react when heated at room temperature or up to about 80°C, and heating to a temperature of 100°C or higher is required for curing.

[0034] (C) Latent curing agents can be selected from those that are conventionally known and used as appropriate. Examples include dicyandiamide, dibasic acid dihydrazide, boron trifluoride amine complex salts, guanamines, melamine, imidazoles, and modified amines.

[0035] Furthermore, (C) commercially available latent curing agents can also be used. For example, dicyandiamide-type latent curing agents include Adeka Hardener EH-3636S and Adeka Hardener EH-4351S. Imidazole-type latent curing agents include Adeka Hardener EH-5011S and Adeka Hardener EH-5046S. Polyamine-type latent curing agents include Adeka Hardener EH-4357S, Adeka Hardener EH-5057P, and Adeka Hardener EH-5057PK (all manufactured by ADEKA Corporation). Amine adduct-type latent curing agents include Amicure PN-23 and Amicure PN-40. Hydrazide-type latent curing agents include Amicure VDH (all manufactured by Ajinomoto Fine Techno Co., Ltd.). These may be used individually or in combination of two or more.

[0036] (C) The amount of latent curing agent is preferably 5 to 30 parts by weight, and more preferably 10 to 20 parts by weight, when the amount of components (A) to (G) in the resin composition is 100 parts by weight.

[0037] <(D)1 Functional (meth)acryloyloxy compound> (D) Monofunctional (meth)acryloyloxy compound is a compound that acts as a solvent for (A) solid epoxy resins and undergoes REDOX polymerization by the action of (E) organic peroxides and (F) reducing agents. It is also a compound that undergoes photoradical polymerization by (G) photoradical initiators.

[0038] Component (D) is monofunctional, having one (meth)acryloyloxy group per molecule, and therefore becomes a linear polymer through REDOX polymerization. Furthermore, since the linear polymer contains one or more epoxy groups, at the temperature at which the latent curing agent (C) cures, component (D) reacts with component (C) in the same way that components (A) and (B) react with component (C), and is ultimately incorporated into the same molecular network.

[0039] Since the mixture of components (A) to (C) becomes solid at room temperature, it is difficult to impregnate the reinforcing fiber substrate with this mixture as is. The first coating step 13, which will be described later, is a step in which the resin composition is applied to and impregnated into the reinforcing fiber substrate, but in the first coating step 13, the resin composition must have low viscosity. Therefore, a solvent is required to reduce the viscosity. The purpose of component (D) as a solvent is to render it non-solvent by REDOX polymerization after application without removing it by evaporation.

[0040] (D) Examples of monofunctional (meth)acryloyloxy compound include glycidyl methacrylate and half-esters of bisphenol A diglycidyl ether and (meth)acrylic acid. Among these, glycidyl methacrylate is preferred because it has low viscosity and is a highly reactive solvent that effectively reduces the viscosity of the mixture of components (A), (B), and (C), making it easier to impregnate into the reinforcing fiber substrate.

[0041] (D) The amount of the functional (meth)acryloyloxy compound is preferably 10 to 50 parts by weight, and more preferably 20 to 40 parts by weight, when the total amount of components (A) to (G) in the resin composition is 100 parts by weight.

[0042] <(E) Regarding organic peroxides> (E) The organic peroxide is a compound that decomposes upon heating to generate radicals. (F) Together with the reducing agent, (D) it initiates the REDOX polymerization reaction of a monofunctional (meth)acryloyloxy compound. The (E) organic peroxide in this embodiment is selected to be of a type that does not generate radicals unless the temperature is high. Therefore, it is substantially inactive at room temperature on its own.

[0043] (E) Examples of organic peroxides include methyl ethyl ketone peroxide, t-butyl peroxybenzoate, cumene hydroperoxide, p-menthane hydroperoxide, t-butyl hydroperoxide, diisopropylbenzene dihydroperoxide, methyl ethyl ketone peroxide, and benzoyl peroxide. These may be used individually or in combination of two or more.

[0044] (E) The amount of organic peroxide added is preferably 1 to 10 parts by weight, and more preferably 0.5 to 5 parts by weight, when the total amount of components (A) to (G) in the resin composition is 100 parts by weight.

[0045] <(F) Regarding reducing agents> (F) The reducing agent reduces and decomposes (E) the organic peroxide at low temperatures, forcing the release of radicals. This REDOX reaction occurs simply by contact with (E) the organic peroxide, without mixing at the molecular level, and the initiated radical polymerization reaction propagates over a certain distance without stirring.

[0046] (F) Examples of reducing agents include reaction condensates of various amines and aldehydes, N,N-dimethylparatoluidine, 2-mercaptobenzimidazole, methylthiourea, dibutylthiourea, tetramethylthiourea, ethylenethiourea, cobalt naphthenate, copper naphthenate, and vanadium compounds. These may be used individually or in combination of two or more.

[0047] (F) The amount of reducing agent is preferably 0.1 to 1 part by weight, and more preferably 0.2 to 0.8 parts by weight, when the amount of components (A) to (G) in the resin composition is 100 parts by weight.

[0048] <(G) Regarding photoradical initiators> (G) Photoradical initiators are compounds that decompose upon UV irradiation to generate radicals. (G) Photoradical initiators undergo (D) monofunctional (meth)acryloyloxy compound photoradical polymerization.

[0049] (G) As a photoradical initiator, one can be appropriately selected from known photoradical generators used in the photopolymerization of (meth)acrylate monomers. Examples include benzophenone, benzyl, Michlar's ketone, thioxanthone derivatives, benzoin ethyl ether, diethoxyacetophenone, benzyldimethyl ketal, 2-hydroxy-2-methylpropiophenone, 1-hydroxycyclohexylphenyl ketone, acylphosphine oxide derivatives, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, 4-benzoyl-4'-methyldiphenyl sulfide, etc. These may be used alone or in combination of two or more.

[0050] <About other additives> The resin composition of the present invention may contain other additives as needed, provided that such additives do not impair functions such as curability. Examples of other additives include reaction accelerators, curing modifiers, storage stabilizers, bulking agents, property modifiers, reinforcing agents, colorants, flame retardants, precipitation inhibitors, antioxidants, anti-aging agents, fragrances, pigments, dyes, and the like.

[0051] <About reinforced fiber base materials> Next, we will explain the reinforced fiber base material. The reinforcing fibers constituting the reinforcing fiber base material can be appropriately selected from conventionally known reinforcing fibers. Specifically, examples include carbon fibers, glass fibers, aramid fibers, basalt fibers, boron fibers, silicon carbide fibers, steel fibers, alumina fibers, tyranno fibers, amorphous fibers, etc. Among these, carbon fibers, which are lightweight and have excellent strength, are preferred.

[0052] The number of reinforcing fibers, fiber diameter, fineness, density, tensile strength, etc., constituting the reinforcing fiber base material are not particularly limited. Commercially available materials can be appropriately selected and used as the reinforcing fiber base material. <About the manufacturing method of prepregs> Next, an embodiment of a manufacturing method for producing a prepreg by coating and impregnating with a resin composition will be described with reference to Figure 1. The prepreg in this embodiment is a toe prepreg obtained by impregnating a resin composition into a reinforcing fiber bundle F, which serves as a reinforcing fiber base material consisting of multiple reinforcing fibers. Hereinafter, it will simply be referred to as prepreg P.

[0053] As shown in Figure 1, in the manufacturing method of prepreg P ​​according to this embodiment, a resin composition is applied to a reinforcing fiber bundle F and impregnated, and then UV irradiation is performed to manufacture prepreg P. The manufacturing method of prepreg P ​​includes an unwinding step 11, a fiber opening step 12, a first coating step 13, a conveying step 14, a second coating step 15, a photocuring step 16, and a winding step 17.

[0054] The prepreg P ​​is manufactured using the prepreg manufacturing apparatus 10 shown in Figure 1. A yarn supply bobbin 21 is located at the uppermost part of the prepreg manufacturing apparatus 10. The unwinding process 11 is the process of drawing out the reinforcing fiber bundle F from the yarn supply bobbin 21. The reinforcing fiber bundle F drawn out from the yarn supply bobbin 21 is conveyed along a plurality of guide rollers 22 and sent to the oiling roller 23.

[0055] In the fiber opening process 12, the reinforcing fiber bundle F is opened while being transported, so that the reinforcing fibers are aligned. The reinforcing fiber bundle F is opened by the time it is transported to the oiling roller 23. The inclusion of the fiber opening process 12 improves the width accuracy of the reinforcing fiber bundle F, and thus improves the width accuracy of the prepreg P ​​that is ultimately manufactured.

[0056] The first coating step 13 is a step of applying and impregnating one side of the reinforcing fiber bundle F with the first agent of the resin composition. The oiling roller 23 is positioned so that its outer circumferential surface contacts the reinforcing fiber bundle F being conveyed, and is configured to rotate along the conveying direction A of the reinforcing fiber bundle F.

[0057] A resin tank 25 is positioned below the oiling roller 23. The resin tank 25 is a box-shaped member that abuts against the bottom of the oiling roller 23. A storage space for storing the first agent is formed between the outer circumferential surface of the oiling roller 23 and the lower and side walls of the resin tank 25. The oiling roller 23 receives the supply of the first agent from the resin tank 25 by passing the first agent stored in the resin tank 25 through a portion of the rotational trajectory of its outer circumferential surface, causing the first agent to adhere to its outer circumferential surface. The first agent supplied to the surface of the oiling roller 23 is adjusted to a predetermined thickness by a scraper 24 positioned on the side of the oiling roller 23.

[0058] In the first coating step 13, the amount of the first agent applied from the resin tank 25 to the reinforcing fiber bundle F is controlled to reach a predetermined target value. Specifically, the weight of the resin tank 25, which stores the first agent supplied to the oiling roller 23, is measured at regular intervals to calculate the amount of resin supplied from the oiling roller 23 to the reinforcing fiber bundle F. In this way, the amount of the first agent applied by the oiling roller 23 (resin content Rc of the first coated body S1) is controlled to converge to a predetermined target value.

[0059] The first agent applied by the oiling roller 23 is impregnated into the interior of the reinforcing fiber bundle F. The reinforcing fiber bundle F coated and impregnated with the first agent is referred to as the first coated body S1. In the conveying process 14, the first coated body S1 is conveyed along a plurality of guide rollers 22.

[0060] The second coating step 15 is a step of applying the second component of the resin composition to one side of the first coated body S1 to which the first component has been applied. By applying the second component, the REDOX reaction of the resin composition is initiated.

[0061] In the second coating step 15, the second agent is sprayed by the coating device 26. The shape, size, length, and coating amount of the coating device 26 can be selected as appropriate. A non-contact microdroplet ejection device, such as a spray method or an inkjet method, is preferred as the coating device 26. The reason for using a non-contact coating device 26 is that the REDOX reaction will start even if the components in the first agent and the (F) reducing agent of the second agent are not mixed at the molecular level, and the radical polymerization that has started will propagate over a certain distance without stirring. The reinforced fiber bundle F coated and impregnated with the second agent will be called the second coated body S2.

[0062] In the second coating S2, the (D) monofunctional (meth)acryloyloxy compound contained in the first agent undergoes REDOX polymerization through the action of (E) organic peroxide and (F) reducing agent contained in the second agent.

[0063] The second coated material S2 is sent to the UV irradiation device 27. The UV irradiation device 27 is located in close proximity to the coating device 26. The photocuring step 16 is a step in which the second coated material S2 is transported within the UV irradiation device 27 and UV irradiation is applied to both sides of the second coated material S2. The UV irradiation device 27 is a box-shaped device with multiple UV irradiation lamps arranged inside. The inner surface of the UV irradiation device 27 is mirrored. Therefore, UV light from the multiple UV irradiation lamps is reflected off the inner surface of the UV irradiation device 27 and efficiently irradiated onto the surface of the transported second coated material S2. In the second coated material S2 transported within the UV irradiation device 27, (D) a monofunctional (meth)acryloyloxy compound undergoes photoradical polymerization by the action of (G) a photoradical initiator. As a result, the polymerization reaction of the (D) monofunctional (meth)acryloyloxy compound proceeds rapidly, and a tack-free prepreg P ​​is obtained.

[0064] The shape, size, and length of the UV irradiation device 27, as well as the number, arrangement, and light intensity of the UV irradiation lamps, can be adjusted as appropriate. These can be set and adjusted in relation to the amount of resin composition applied to the second coated body S2, the thickness of the second coated body S2, the transport speed, etc.

[0065] A winding roller 28 is located at the downstream end of the prepreg manufacturing apparatus 10. The winding process 17 is the process of winding tack-free prepreg P ​​onto the winding roller 28. The prepreg P ​​conveyed from the UV irradiation device 27 is conveyed along the guide roller 22 and wound onto the winding roller 28 while applying a predetermined pressure.

[0066] In the winding process 17 of this embodiment, the prepreg P ​​is wound onto the winding roller 28 in a record winding manner. Record winding is a method of winding the prepreg P ​​onto the winding roller 28 without shifting the winding position of the prepreg P, by aligning and overlapping both ends of the prepreg P ​​in the width direction. Since the surface of the prepreg P ​​is tack-free, the reinforcing fibers derived from the reinforcing fiber bundle F are not exposed on the surface. Even with record winding, where the prepreg is wound sequentially to the same position, it is unlikely that the reinforcing fibers will become interlocked and difficult to unwind. In addition, the resin compositions applied to the prepreg P ​​are not adhesive to each other, and it can be stored at room temperature without developing tackiness.

[0067] Through the above process, prepreg P ​​is manufactured by the prepreg manufacturing apparatus 10. <About the effects of prepreg P> Next, we will explain the function of prepreg P ​​coated and impregnated with the resin composition.

[0068] At room temperature, polymerization reactions between (A) solid epoxy resin and (B) liquid epoxy resin do not occur due to (C) latent curing agent. However, because (A) solid epoxy resin has film-forming ability, the fluidity of the entire resin composition is lost and it becomes solid even in the presence of (B) liquid epoxy resin. Furthermore, (D) monofunctional (meth)acryloyloxy compound acts as a solvent for (A) solid epoxy resin and loses its solvent function through REDOX polymerization by the action of (E) organic peroxide and (F) reducing agent.

[0069] These effects result in a tack-free surface for prepreg P, and polymerization of (D)1-functional (meth)acryloyloxy compound occurs within the prepreg P. As a result, fluctuations in polymer concentration are suppressed throughout the prepreg P. Furthermore, polymerization of the resin composition throughout the interior increases the restraining force between the fibers constituting the reinforcing fiber bundle F. Changes in the shape and width of prepreg P ​​when heated and pressurized are suppressed.

[0070] Here, let's assume that the reinforcing fibers constituting the reinforcing fiber bundle F are, for example, carbon fibers. Carbon fibers are black. Therefore, if photoradical polymerization is carried out using only (G) a photoradical initiator, when UV light hits the carbon fibers, it becomes difficult for the UV light to penetrate further into the interior. As a result, the photoradical reaction is difficult to occur inside the second coating S2, and the resin composition remains uncured. This is particularly noticeable when the reinforcing fibers are dark-colored carbon fibers, aramid fibers, basalt fibers, etc. Furthermore, even with transparent glass fibers, if the thickness of the reinforcing fiber bundle F is large, it may be difficult for UV light to reach the resin composition inside, and photocuring inside may not proceed.

[0071] In this regard, the resin composition of this embodiment contains (E) an organic peroxide and (F) a reducing agent, which allows the polymerization of (D) a monofunctional (meth)acryloyloxy compound by the REDOX polymerization reaction to proceed. As a result, for example, even in the case of a dark-colored reinforcing fiber bundle F, the polymerization reaction of the resin composition proceeds to the interior of the prepreg P.

[0072] The resin composition further contains (G) a photoradical initiator, and in the photocuring step 16, the second coated body S2 is subjected to UV irradiation by a UV irradiation device 27. UV irradiation promotes the photoradical polymerization reaction of (D) a monofunctional (meth)acryloyloxy compound by the (G) photoradical initiator in the resin composition. This promotes the polymerization reaction of the resin composition.

[0073] At room temperature, polymerization of (A) solid epoxy resin and (B) liquid epoxy resin by (C) latent curing agent does not occur. However, because (A) solid epoxy resin has film-forming ability, the fluidity of the entire resin composition is lost and it becomes solid even in the presence of (B) liquid epoxy resin. By mixing (B) liquid epoxy resin with (A) solid epoxy resin, it is possible to achieve a delicate balance of fluidity, and when pressurized or heated, the entire resin composition can be appropriately refluidified.

[0074] Furthermore, the (D) monofunctional (meth)acryloyloxy compound acts as a solvent for the (A) solid epoxy resin, and loses its solvent function through REDOX polymerization by the action of the (E) organic peroxide and the (F) reducing agent. Since component (D) is monofunctional, having one (meth)acryloyloxy group per molecule, it becomes a linear polymer through REDOX polymerization.

[0075] Therefore, although the resin composition ceases to be liquid, it re-liquidates upon heating, making it less likely to hinder the overall fluid deformation and fusion of the resin composition. When molding a molded product using prepreg P, for example, the prepreg P ​​is wrapped around a predetermined core material and laminated. During this process, a predetermined pressure is applied to the prepreg P, and it is wrapped while being heated. When pressurized and heated, the entire resin composition reflows appropriately, so the prepreg P ​​exhibits appropriate tackiness during molding. The tackiness of the prepreg P ​​is achieved with only slight pressurization and heating. This makes it difficult for the prepreg P ​​layers to shift during lamination. This fluidized state can also be achieved by heating at low temperatures of around 40°C. By the resin composition exhibiting a fluidized state, displacement of the laminated prepreg P ​​is suppressed, resulting in good lamination properties. Compared to cases where the acrylic compound is crosslinked in a mesh-like structure, the prepreg P ​​exhibits tackiness more easily when heated at low temperatures, making it easier to laminate.

[0076] On the other hand, (D) a monofunctional (meth)acryloyloxy compound undergoes REDOX polymerization through the action of (E) an organic peroxide and (F) a reducing agent, and the reinforcing fiber bundle F is constrained by the polymerized resin composition. This constraining force does not change when heated up to about 80°C. Therefore, even when heated at a low temperature to exhibit tackiness, the shape retention of the prepreg P ​​is good.

[0077] During the molding of the molded product, prepreg P ​​is laminated and heated to the curing temperature of the latent curing agent (C). The latent curing agent (C) reacts with the epoxy groups of the solid epoxy resin (A) and the liquid epoxy resin (B) to cure. Heating also causes the organic peroxide (E) to decompose and generate radicals, which act as initiators for the radical polymerization of the (meth)acryloyloxy groups of component (D). Since the linear polymer polymerized by REDOX polymerization of component (D) contains one or more epoxy groups, at the temperature in which the latent curing agent (C) cures, component (D) reacts with component (C) in the same way as components (A) and (B), and is ultimately incorporated into the same molecular network.

[0078] In this manner, when the prepreg P ​​is laminated and heated to the curing temperature of the latent curing agent (C), the resin composition hardens. This improves the strength of the molded product. Next, the effects of the resin composition and the method for producing the prepreg P ​​according to the above embodiment will be described.

[0079] (1) The resin composition used in the manufacturing method of prepreg P ​​is a two-component mixture consisting of a first component and a second component, the first component containing (A) a solid epoxy resin, (B) a liquid epoxy resin, (C) a latent curing agent, (D) a monofunctional (meth)acryloyloxy compound, and (E) an organic peroxide. The second component contains (F) a reducing agent.

[0080] By mixing the first and second agents, the (D) monofunctional (meth)acryloyloxy compound contained in the first agent reacts with the (E) organic peroxide and the (F) reducing agent contained in the second agent, causing the REDOX polymerization reaction of the (D) monofunctional (meth)acryloyloxy compound to proceed. The surface of the prepreg P ​​becomes tack-free, allowing for smooth winding and unwinding without release paper. Furthermore, fluctuations in the concentration of polymers within the prepreg P ​​are suppressed, increasing the restraining force of the reinforcing fiber bundle F. As a result, the shape retention of the prepreg P ​​is improved, and misalignment of the prepreg P ​​during lamination is suppressed.

[0081] (2)(B) The liquid epoxy resin, when mixed with (A) the solid epoxy resin, allows for a delicate balance of fluidity, and when heated, it can moderately re-fluidize the entire resin composition. Therefore, it is less likely to hinder the fluid deformation and fusion of the entire resin composition.

[0082] (3) Because the solid epoxy resin (A) contained in the first agent has film-forming ability, the fluidity of the entire resin composition is lost and it becomes solid even in the presence of the liquid epoxy resin (B). By mixing the liquid epoxy resin (B) with the solid epoxy resin (A), it is possible to achieve a delicate balance of fluidity, and when pressurized and heated, the entire resin composition can be appropriately refluidified.

[0083] Therefore, a prepreg P ​​can be obtained that is tack-free on the surface, yet possesses appropriate tackiness when pressurized and heated. When prepreg P ​​is laminated during molding, the laminated prepreg P ​​is less prone to misalignment and is easy to handle. High-quality molded products can be formed.

[0084] (4) The surface of prepreg P ​​is tack-free. Therefore, it can be stored at room temperature and has good storage properties. (5) The resin composition contains (G) a photoradical initiator. In the above embodiment, component (D) is subjected to a REDOX polymerization reaction with (E) an organic peroxide and (F) a reducing agent, and is also subjected to photoradical polymerization by UV irradiation.

[0085] Therefore, when the second coated body S2, to which the resin composition has been applied and impregnated, is irradiated with UV light, the photoradical polymerization reaction of the (D) monofunctional (meth)acryloyloxy compound is promoted by the (G) photoradical initiator. The polymerization reaction of the resin composition can be rapidly carried out from the surface of the prepreg P. The prepreg P ​​can be manufactured while the reinforcing fiber bundle F is transported at high speed.

[0086] Furthermore, UV irradiation only reaches a depth of approximately 50 μm from the surface of the second coating S2. Within this range, component (D) undergoes radical polymerization, but radical polymerization does not proceed beyond this depth. Therefore, even if it takes time for all of component (D) to undergo REDOX polymerization, UV irradiation can accelerate the polymerization reaction of component (D). By quickly making the surface of prepreg P ​​tack-free and enabling winding, the production efficiency of prepreg P ​​can be improved.

[0087] (6) The resin composition contains (D) a monofunctional (meth)acryloyloxy compound. It polymerizes linearly by REDOX polymerization or photoradical reaction. Therefore, when prepreg P ​​is laminated while being heated and pressurized, the fluid deformation and welding of the resin composition, which is re-fluidified by heating, are less likely to be inhibited. Prepreg P ​​exhibits appropriate tackiness, resulting in good lamination properties for prepreg P.

[0088] (7)(D)1 Because the functional (meth)acryloyloxy group compound is polymerized in a linear manner, it exhibits tackiness more easily even when heated at low temperatures compared to cases where the acrylic compound is crosslinked in a network manner. This eliminates the need for molding equipment with a heating process that has a large heat capacity, and allows for molding with more compact molding equipment.

[0089] (8)(D)1 Functional (meth)acryloyloxy compound is polymerized by the REDOX polymerization reaction. Therefore, even if the reinforcing fibers constituting the reinforcing fiber bundle F are dark-colored carbon fibers or the like, the polymerization of the (D)1-functional (meth)acryloyloxy group compound proceeds without concentration fluctuations throughout the interior of the second coating S2.

[0090] (9) The method for manufacturing the prepreg P ​​according to the above embodiment includes a conveying step 14 in which the reinforcing fiber bundle F is conveyed along a guide roller 22, a first coating step 13 in which the first agent is applied to one side of the reinforcing fiber bundle F to form a first coated body S1, a second coating step 15 in which the second agent is applied to the side of the first coated body S1 to form a second coated body S2, and a winding step 17 in which the second coated body S2 is wound onto a winding roller 28. In the first coating step 13, the reinforcing fiber bundle F is conveyed along an oiling roller 23 on which a resin composition is supplied to the circumferential surface.

[0091] Therefore, in the transported second coating S2, (D) a monofunctional (meth)acryloyloxy compound is polymerized using (E) an organic peroxide and (F) a reducing agent in a REDOX process. This simplifies the process by eliminating the need to apply the resin composition to release paper and then attach it to the reinforcing fiber bundle F, or to peel off the release paper. This allows for the efficient production of a tack-free prepreg P ​​with good shape retention.

[0092] (10) The method for manufacturing the prepreg P ​​of the above embodiment includes a photocuring step 16 in which UV light is irradiated on both sides of the second coated body S2. Therefore, (D) the monofunctional (meth)acryloyloxy compound undergoes photoradical polymerization by (G) the photoradical initiator. This allows the polymerization reaction of (D) the monofunctional (meth)acryloyloxy compound to proceed more rapidly. This enables high-speed transport of reinforcing fiber bundles F and prepreg P. The resin composition on the surface of prepreg P ​​can be polymerized quickly. The surface of prepreg P ​​can be made tack-free quickly, allowing for efficient production of prepreg P.

[0093] (11) In the photocuring process 16, the second coated body S2 is transported inside a UV irradiation device 27 whose inner surface is mirrored. Therefore, UV irradiation can be applied uniformly to both sides of the second coated material S2. The entire surface of the prepreg P ​​becomes uniformly tack-free, and its quality is stabilized. In addition, since photocuring can be performed while conveying, the equipment configuration is simplified.

[0094] (12) In the photocuring process 16, the second coated material S2 is transported inside the UV irradiation device 27. Therefore, by adjusting the shape, size, and length of the UV irradiation device 27, the number, arrangement, and light intensity of the UV irradiation lamps, and the transport speed of the second coated material S2, the surface of the prepreg P ​​can be brought to a desired state.

[0095] (13) The method for manufacturing prepreg P ​​includes a fiber opening step 12. Therefore, the reinforcing fibers constituting the reinforcing fiber bundle F are aligned, improving the width accuracy of the reinforcing fiber bundle F.

[0096] (14) The fiber opening process 12 is located upstream of the first coating process 13. Therefore, the resin composition is applied to and impregnated into the aligned reinforcing fiber bundle F. This improves the width accuracy of the prepreg P.

[0097] (15) The first coating step 13 involves transporting the reinforcing fiber bundle F along the oiling roller 23 on which the resin composition has been supplied to the circumferential surface. Therefore, the resin composition can be continuously applied to the surface of the reinforcing fiber bundle F. High-speed resin impregnation is possible.

[0098] The above embodiment can be modified as follows. Note that the above embodiment and the following modifications can be combined and applied to the extent that they do not contradict each other technically. The resin composition can be used not only in the manufacture of tow prepregs, but also in the manufacture of sheet prepregs and prepreg tapes.

[0099] • The first agent does not need to contain (G) a photoradical initiator. The second agent may contain (A) a solid epoxy resin, (B) a liquid epoxy resin, (C) a latent curing agent, and (D) a monofunctional (meth)acryloyloxy compound in addition to (F) a reducing agent. When the second agent contains components (A) to (D), its viscosity and content ratio can be made equal to that of the first agent, making it easy to mix with the first agent. When the second agent contains components (A) to (D), its viscosity is higher than when it does not contain them, so it is preferable that the second coating step 15 is performed by applying the second agent with an oiling roller, similar to the first coating step 13.

[0100] In the first coating step 13, the first agent may be applied to both sides of the reinforcing fiber bundle F. In this case, an additional oiling roller can be placed downstream of the oiling roller 23. The reinforcing fiber bundle F can then be conveyed along the oiling roller 23 to apply the first agent to one side, and then conveyed along the downstream oiling roller to apply the first agent to the other side. The amount of resin of the first agent supplied to the downstream oiling roller can be adjusted based on the amount of resin supplied to the reinforcing fiber bundle F from the oiling roller 23. In this way, the amount of the first agent applied by the two oiling rollers (resin content Rc of the first coated body S1) can be controlled to converge to a predetermined target value.

[0101] When applying the first agent to both sides of the reinforcing fiber bundle F with two oiling rollers in the first coating step 13, the two oiling rollers are not limited to being positioned along the transport direction A of the reinforcing fiber bundle F as described above. The oiling rollers may be positioned so as to simultaneously sandwich both sides of the reinforcing fiber bundle F.

[0102] In the second coating step 15, the second agent may be applied to both sides of the first coated body S1. The supply of the resin composition to the oiling roller 23 does not necessarily have to be via the resin tank 25. For example, a predetermined amount of the resin composition may be dropped or applied to the surface of the oiling roller 23.

[0103] The prepreg manufacturing apparatus 10 is not limited to the configuration shown in Figure 1. For example, known feed rollers, nip rollers, dancer rollers, etc., may be provided to adjust the transport speed of the reinforcing fiber bundle F, the first coating S1, the second coating S2, and the prepreg P, or to apply tension. Also, there may be more guide rollers 22 than shown. [Examples]

[0104] The shape retention of prepreg P ​​coated and impregnated with a resin composition embodying the present invention was evaluated. (Examples) A resin composition containing components (A) to (G) was prepared. Here, instead of preparing the first and second components separately, the composition was prepared containing all components (A) to (G). Component (A) is JER(registered trademark) 1004 (manufactured by Mitsubishi Chemical Corporation), component (B) is JER(registered trademark) 828 (manufactured by Mitsubishi Chemical Corporation), component (C) is dicyandiamide, component (D) is glycidyl methacrylate, component (E) is methyl ethyl ketone peroxide, component (F) is cobalt naphthenate, and component (G) is Omnirad 184 (1-hydroxycyclohexyl phenyl ketone). The prepared resin composition was coated onto DuPont's Tedlar(registered trademark) PVF film. The content of each component in the resin composition (in g) is shown in Table 1. As the reinforcing fiber bundle F to which the resin composition was applied and impregnated, we used Tenax® filament STS40 (wall thickness 0.6 mm, manufactured by Teijin Limited), which is a carbon fiber bundle.

[0105] DuPont's Tedlar® PVF film coated with a resin composition was bonded to a carbon fiber bundle, and the carbon fiber bundle coated and impregnated with the resin composition was used to obtain the prepreg P ​​of the example. Subsequently, the prepreg P ​​of the example was placed on a heated table, and 4 kg·m of the prepreg P ​​was applied from above using a roller. ー1 ·s ー2 The material was pressurized. Heating temperatures were set at 40°C, 60°C, and 80°C. The width of the carbon fiber bundles of prepreg P ​​was measured after heating and pressurizing, and the percentage change compared to the width before heating and pressurizing was calculated. The percentage change was the average value measured at three locations on the carbon fiber bundles of prepreg P. The results are shown in Figure 2.

[0106] (Comparative Example 1) A resin composition having the same composition as in the example, except that it did not contain component (F), was applied to and impregnated into the reinforcing fiber bundle F in the same manner as in the example. Subsequently, UV irradiation was performed to photo-radical polymerization of (D) a monofunctional (meth)acryloyloxy compound with (G) a photo-radical initiator to obtain prepreg P ​​of Comparative Example 1. After photo-radical polymerization, heating and pressurization were performed in the same manner as in the example, and the percentage change in the width of the carbon fiber bundle after heating and pressurization was calculated. The results are shown in Figure 2.

[0107] (Comparative Example 2) A resin composition having the same composition as in the example, except that it did not contain components (D) to (G), was applied to and impregnated into a reinforcing fiber bundle F in the same manner as in the example to obtain the prepreg P ​​of Comparative Example 2. The material was heated and pressurized in the same manner as in the example, and the percentage change in the width of the carbon fiber bundle after heating and pressurizing was calculated. The results are shown in Figure 2.

[0108] [Table 1]

[0109] As shown in Figure 2, in the example, no change was observed in the width of the carbon fiber bundles when heated to any of the temperatures of 40°C, 60°C, or 80°C. The shape retention was good. Furthermore, the surface of the prepreg P ​​in the example was tack-free. On the other hand, in Comparative Example 2, the width of the carbon fiber bundles expanded by more than 30% even when heated to 40°C. The rate of change in width was greater when heated to 60°C and 80°C than at 40°C. Also, the viscosity of the resin composition applied to and impregnated into the prepreg P ​​was high, and the surface of the prepreg P ​​exhibited tackiness.

[0110] In the example, the prepreg P ​​contains a (G) photoradical initiator in the resin composition coated and impregnated onto the carbon fiber bundle, but in this example, the prepreg P ​​was not irradiated with UV light. In this regard, if the prepreg P ​​is irradiated with UV light, the polymerization reaction of the (D) monofunctional (meth)acryloyloxy group compound will proceed more rapidly due to the photoradical polymerization of the (D) monofunctional (meth)acryloyloxy group compound. Therefore, although the results are not shown, it is thought that even if the prepreg P ​​of the example is irradiated with UV light, the shape of the carbon fiber bundle will not change due to heating and pressurization. Furthermore, it is thought that this effect will appear earlier than in the prepreg P ​​of the example.

[0111] In the prepreg P ​​of Comparative Example 1, the change in the width of the carbon fiber bundle was smaller than that of Comparative Example 2, but still around 5-6%. The resin composition of Comparative Example 1 contains (D) a monofunctional (meth)acryloyloxy compound and (G) a photoradical initiator, and the (D) monofunctional (meth)acryloyloxy compound is photoradical polymerized by the (G) photoradical initiator by UV irradiation. In Comparative Example 1, even when heated at a relatively low temperature of 40°C, the width of the carbon fiber bundle expanded by approximately 5%. In this study, a carbon fiber bundle with a thickness of 0.6 mm was used, but it is thought that the change in width would be even greater for carbon fiber bundles with a thickness greater than 0.6 mm.

[0112] Since carbon fibers are black, in the prepreg P ​​of Comparative Example 1, when UV light is irradiated onto the carbon fibers, the UV light does not reach the resin composition inside, and photoradical polymerization does not proceed inside. Therefore, in Comparative Example 1, the degree of polymerization of the resin composition differs between the surface and the interior of the prepreg P, and uncured resin composition remains inside. This is thought to be reflected in the rate of change in the width of the carbon fiber bundle during heating and pressurization, as described above. [Explanation of Symbols]

[0113] F... Reinforcement fiber bundle (reinforcement fiber base material) P...Prepreg S1...First coated material S2...Second coating (coating) 13...First coating process 15…Second application process 16...Light curing process 17…Winding process 23… Oiling roller

Claims

1. A resin composition comprising a first agent and a second agent, which is applied to a reinforcing fiber substrate to manufacture a prepreg, The first agent is (A) Solid epoxy resin having film-forming properties, (B) Liquid epoxy resin, (C) Latent curing agent for epoxy resins, (D) A compound having one (meth)acryloyloxy group and one or more epoxy groups in one molecule. (E) Organic peroxide (G) Photoradical initiator It contains, The second agent is (F) Reducing agent It contains, The ratio of component (A) to component (B) is in the range of 1:2 to 2:

1. A resin composition in which the amount of component (D) is 20 to 50 parts by weight when the total amount of components (A) to (G) is 100 parts by weight.

2. A prepreg characterized by comprising the resin composition described in claim 1 and a reinforcing fiber substrate.

3. A method for manufacturing a prepreg used to form a molded product by impregnating a reinforcing fiber substrate with the resin composition described in claim 1, laminating multiple layers of the resin composition, and then thermally curing the resin composition, A conveying step of conveying the reinforced fiber substrate along a roller, A first coating step involves applying the first agent to at least one surface of the reinforcing fiber substrate to form a first coated body, A second coating step in which the second agent is applied to the surface on which the first agent has been applied in the first coating body to form a coating body, A winding step in which the coated material is wound onto a winding roller. Equipped with, The method for manufacturing a prepreg is characterized in that the first coating step involves transporting the reinforcing fiber substrate along an oiling roller on which the resin composition has been supplied to its circumferential surface.

4. The method for producing a prepreg according to claim 3, further comprising a photocuring step of irradiating both sides of the coated body with UV light.

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