Molding materials and fiber-reinforced composite materials

Abstract

The present invention addresses the problem of providing a molding material for fiber-reinforced composite materials, which is prevented from the volatilization of a portion of components after long-term storage and has excellent tackiness and fluidability during press molding. The present invention also addresses the problem of providing a fiber-reinforced composite material which can exert excellent surface smoothness and mechanical properties when cured at a high temperature.　The present invention is a molding material which comprises an epoxy resin composition comprising components (A) to (C) and reinforcing fibers, in which the content of the reinforcing fibers in the molding material is 30 to 90% by mass, inclusive, the content of the component (A) in the epoxy resin composition is 20 to 75% by mass, inclusive, and the formula (1) is satisfied. The component (A): a bisphenol-type epoxy resin having a number average molecular weight of 250 to 365, inclusive; the component (B): a latent curing agent; the component (C): an acid anhydride and / or an isocyanate compound; and 0.14 ≦ Wc / Wb ≦ 2.00 wherein Wb is the number of moles of active hydrogen in the component (B), and Wc is the number of moles of the component (C).

Description

[Technical Field]

[0001] The present invention relates to a molding material that is suitably used for fiber-reinforced composite materials for aerospace components, automotive components, etc., and to a fiber-reinforced composite material using the same. [Background technology]

[0002] Fiber-reinforced composite materials, consisting of reinforcing fibers and a matrix resin, have been used for a variety of purposes, including structural materials for aircraft and automobiles, as well as for sports and general industrial applications such as tennis rackets, golf shafts, and fishing rods, due to their high specific strength and specific modulus. Reinforcing fibers include glass fiber, aramid fiber, carbon fiber, and boron fiber. From the perspective of mechanical properties such as strength and rigidity, molding materials for fiber-reinforced composites with a high mass content of reinforcing fibers are preferred. While both thermosetting and thermoplastic resins are used as matrix resins, thermosetting resins are often used due to their heat resistance and productivity. Examples of thermosetting resins include epoxy resins, unsaturated polyester resins, vinyl ester resins, phenolic resins, bismaleimide resins, and cyanate resins. Epoxy resins are particularly preferred due to their adhesion between the resin and reinforcing fibers and dimensional stability.

[0003] Fiber-reinforced composites are manufactured using a variety of methods, including hand layup, filament winding, pultrusion, resin transfer molding (RTM), and press molding of fiber-reinforced composite molding materials such as prepregs, towpregs, bulk molding compounds (BMCs), and sheet molding compounds (SMCs). These fiber-reinforced composite molding materials are produced by impregnating reinforcing fibers with a matrix resin. BMCs and SMCs are then produced by thickening the resin composition by leaving them at room temperature or by heat treatment. Known thickening techniques for epoxy resins include dissolving or swelling thermoplastic particles or thermoplastic resins in the epoxy resin, reacting epoxy groups with amines or acid anhydrides to form crosslinked structures, and reacting isocyanates with hydroxyl groups to form polyurethanes in the system.

[0004] Fiber-reinforced composite molding materials obtained using the above-mentioned thickening technology are rarely used immediately after production; they are generally stored for 30 days or more before use. Therefore, when fiber-reinforced composite molding materials are stored for long periods of time, some of the components volatilize or the viscosity increases further, resulting in problems with the tackiness and fluidity during press molding of the fiber-reinforced composite molding materials. Therefore, there is a need to resolve these issues and ensure that the tackiness and fluidity during press molding of fiber-reinforced composite molding materials remain stable even after long-term storage. Furthermore, in recent years, measures to reduce volatile organic compounds (VOCs) in living environments have been promoted in response to the issue of sick building syndrome. Against this social background, the volatility of organic compounds in the interior environments of automobiles and aircraft has also become a concern. While technological development aimed at reducing the volatility of organic compounds has been particularly significant in the coatings industry, there is also a growing demand for reducing the volatility of organic compounds in the fiber-reinforced composite materials themselves. Generally, fiber-reinforced composite materials are molded using molding compounds for fiber-reinforced composites, heated at temperatures below 150°C, whereas the coating process involves treatment for several hours at higher temperatures of around 160 to 200°C. This coating process poses the problem of some of the components on the surface of the fiber-reinforced composite volatilizing, deteriorating the surface smoothness of the volatilized fiber-reinforced composite. Therefore, it was necessary for the resulting fiber-reinforced composite material to have excellent surface smoothness and mechanical properties without volatilizing some of the components, even when treated at high temperatures.

[0005] In response to this situation, a molding material for a fiber-reinforced composite material has been disclosed that uses an epoxy resin composition containing a bisphenol-type epoxy and an acid anhydride that is liquid at 25°C (Patent Documents 1 and 2). Also, a molding material for a fiber-reinforced composite material has been disclosed that uses an epoxy resin composition containing an isocyanate that is liquid at 25°C (Patent Document 3). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] International Publication No. 2020 / 050200 [Patent Document 2] International Publication No. 2018 / 190329 [Patent Document 3] International Publication No. 2018 / 216643 Summary of the Invention [Problem to be solved by the invention]

[0007] According to the molding materials for fiber-reinforced composite materials described in Patent Documents 1 and 2, the molding materials for fiber-reinforced composite materials hardened and had low tackiness after long-term storage. Furthermore, the molding materials for fiber-reinforced composite materials did not flow sufficiently during molding due to long-term storage, resulting in underfill at the edges of the fiber-reinforced composite material. Furthermore, when the resulting fiber-reinforced composite material was treated at high temperatures, the surface of the fiber-reinforced composite material became rough and its smoothness deteriorated.

[0008] According to the molding material for fiber-reinforced composite materials described in Patent Document 3, although the change in the molding material for fiber-reinforced composite materials due to long-term storage is small, as the shapes of end products become more complex and the variety of products increases, there is a problem in that the tackiness needs to be controlled at a higher level when laminating into complex mold shapes. Also, when molding a complex shape using a molding material for fiber-reinforced composite materials after long-term storage, it is necessary to control the flowability at a higher level. Furthermore, when treating the resulting fiber-reinforced composite materials at high temperatures, it is necessary to maintain a higher level of surface smoothness of the fiber-reinforced composite materials.

[0009] Therefore, an object of the present invention is to provide a molding material for a fiber-reinforced composite material that suppresses volatilization of some components after long-term storage and has excellent tackiness and flowability during press molding, and further to provide a fiber-reinforced composite material that has excellent surface smoothness and mechanical properties even when cured at high temperatures. [Means for solving the problem]

[0010] In order to solve the above problems, the present invention has the following configuration.

[0011] That is, the present invention provides a molding material containing an epoxy resin composition containing the following components (A) to (C) and reinforcing fibers, wherein the content of reinforcing fibers in the molding material is 30% by mass or more and 90% by mass or less, the content of component (A) in the epoxy resin composition is 20% by mass or more and 75% by mass or less, and the epoxy resin composition satisfies the following formula (1): Component (A): Bisphenol-type epoxy resin with a number-average molecular weight of 250 or more and 360 or less Component (B): Latent curing agent Component (C): At least one compound selected from the group consisting of acid anhydrides and isocyanate compounds 0.14≦Wc / Wb≦2.00 …(1) Here, Wb: Number of moles of active hydrogen in component (B) Wc: Number of moles of component (C).

[0012] The present invention also relates to a fiber-reinforced composite material obtained by curing the molding material of the present invention. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide a molding material for a fiber-reinforced composite material that suppresses volatilization of some components after long-term storage and has excellent tackiness and flowability during press molding. Furthermore, by using such a molding material for a fiber-reinforced composite material, it is possible to provide a fiber-reinforced composite material that has excellent surface smoothness and mechanical properties even when cured at high temperatures. DETAILED DESCRIPTION OF THE INVENTION

[0014] Preferred embodiments of the present invention will be described below.

[0015] (molding material) The molding material of the present invention contains an epoxy resin composition and reinforcing fibers.

[0016] (Epoxy resin composition) The epoxy resin composition in the molding material of the present invention contains the following components (A) to (C): Component (A): a bisphenol-type epoxy resin having a number-average molecular weight of 250 or more and 365 or less; Component (B): a latent curing agent; Component (C): an acid anhydride and / or an isocyanate compound.

[0017] (Component (A)) Component (A) in the present invention is a component necessary for exhibiting heat resistance and mechanical properties. Here, the bisphenol-type epoxy resin refers to a compound containing one or more epoxy groups in the molecule and having a bisphenol skeleton.

[0018] The number average molecular weight of the epoxy resin was measured by GPC (Gel Permeation Chromatography) using a polystyrene standard sample. The number average molecular weight of the epoxy resin in the molding material can be determined by extracting the resin component from the molding material using a solvent and analyzing the resulting extract by GPC.

[0019] In the molecular weight distribution for measuring the number average molecular weight, if there is a peak outside the above range and a valley due to overlap with the base of the peak, the point where the minimum value is obtained in the valley is used as the cutoff point.

[0020] It is important that the bisphenol epoxy resin of component (A) has a number average molecular weight of 250 or more and 365 or less. By having a number average molecular weight of 250 or more, preferably 300 or more, the bisphenol epoxy resin can be made less likely to volatilize during the production of the molding material, during molding, and during long-term storage. Furthermore, by having a number average molecular weight of 365 or less, preferably 350 or less, the epoxy resin composition can be made low-viscosity and have excellent impregnation properties into reinforcing fibers.

[0021] Examples of bisphenol-type epoxy resins for component (A) include bisphenol A-type epoxy resins, bisphenol F-type epoxy resins, and epoxy resins modified from these. Two or more of these may be used in combination. Among these, bisphenol F-type epoxy resins are preferred because of their excellent impregnation ability into reinforcing fibers.

[0022] Commercially available bisphenol A epoxy resins include jER (registered trademark) 825 and jER (registered trademark) 826 (both manufactured by Mitsubishi Chemical Corporation), Epiclon (registered trademark) 850-CRP (manufactured by DIC Corporation), Epototo (registered trademark) YD8125 (manufactured by Nippon Steel & Sumitomo Metal Chemical Co., Ltd.), and DER (registered trademark) -330.

[0023] Commercially available bisphenol F epoxy resins include jER (registered trademark) 806 and jER (registered trademark) 807 (both manufactured by Mitsubishi Chemical Corporation), Epicron (registered trademark) 830 (manufactured by DIC Corporation), Epototo (registered trademark) YDF170, Epototo (registered trademark) YDF175, and Epototo (registered trademark) YDF8170 (all manufactured by Nippon Steel & Sumitomo Metal Chemical Co., Ltd.).

[0024] It is important that the content of component (A) in the epoxy resin composition is 20% by mass or more and 75% by mass or less. By having the mass proportion of component (A) 20% by mass or more, preferably 40% by mass or more, it is possible to achieve good fluidity even after long-term storage. Furthermore, by having the mass proportion of component (A) 75% by mass or less, preferably 70% by mass or less, it is possible to achieve a sufficient effect of improving tackiness even after long-term storage.

[0025] (Component (B)) The latent curing agent of component (B) in the present invention is necessary for heat resistance and curing rate control. Component (B) is not particularly limited as long as it has active hydrogen and can cure epoxy resins, but examples include amines, phenols, mercaptans, imidazoles, organic phosphorus compounds, urea compounds, ammonium salts, and sulfonium salts.

[0026] Examples of amine-based curing agents include dicyandiamide, aromatic polyamines, aliphatic amines, aminobenzoic acid esters, thiourea-added amines, and hydrazides. Examples of phenol-based curing agents include bisphenols, phenol novolac resins, cresol novolac resins, and polyphenol compounds. Examples of mercaptan-based curing agents include polymercaptans and polysulfide resins. Among these examples, dicyandiamide or its derivatives, and imidazole-based compounds are preferred from the viewpoint of curing speed. Dicyandiamide or its derivatives are more preferred. A derivative of dicyandiamide refers to a compound obtained by combining dicyandiamide with various compounds. Dicyandiamide and its derivatives are particularly excellent in imparting high flexural strength and heat resistance to cured resins, and also provide excellent storage stability to resin compositions.

[0027] Examples of derivatives of dicyandiamide include those obtained by combining dicyandiamide with various compounds such as epoxy resins, vinyl compounds, acrylic compounds, and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide.

[0028] Examples of imidazole compounds include 2-methylimidazole, 2-phenylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 2-ethyl-4-methylimidazole, 2-methylimidazolium isocyanurate, 2-phenylimidazolium isocyanurate, and 2,4-diamino-6-[2'-methylimidazolyl-(1')-ethyl]-triazine.

[0029] These may be used alone or in combination of two or more. The combined use of two or more is preferred because it allows for more precise control of the initiation temperature of the epoxy curing reaction, thereby further suppressing volatilization during curing.

[0030] Commercially available dicyandiamide products include DICY7 and DICY15 (both manufactured by Mitsubishi Chemical Corporation).

[0031] Commercially available imidazole products include Curazol (registered trademark) 1,2DMZ, Curazol (registered trademark) 2E4MZ, Curazol (registered trademark) C11Z, Curazol (registered trademark) C17Z, Curazol (registered trademark) 2PZ-PW, Curazol (registered trademark) 2P4MZ, Curazol (registered trademark) 2MZ-CN, Curazol (registered trademark) 1B2MZ, Curazol (registered trademark) 2PZCNS-PW, Curazol (registered trademark) 2MA-OK, Curazol (registered trademark) 2MZA-PW, Curazol (registered trademark) 2E4MA-A, Curazol (registered trademark) C11Z-A, and Curazol (registered trademark) 2P4MHZ-PW (all manufactured by Shikoku Chemicals Corporation).

[0032] The melting point of component (B) is preferably 200°C or higher and 300°C or lower. A melting point of 200°C or higher allows the molding material to maintain the same fluidity during molding as immediately after production, even after long-term storage. Furthermore, a melting point of 300°C or lower allows the molding material to be molded using typical molds and ovens used in press molding.

[0033] The content of component (B) in the epoxy resin composition is preferably 1% by mass or more and 15% by mass or less. When component (B) is 1% by mass or more, more preferably 5% by mass or more, a sufficient effect of improving curability can be obtained. Furthermore, when component (B) is 15% by mass or less, more preferably 10% by mass or less, heat resistance of the cured product of the epoxy resin composition can be effectively obtained.

[0034] (Component (C)) Component (C) is an acid anhydride and / or an isocyanate compound, and is a component necessary for achieving excellent tackiness and fluidity in the present invention.

[0035] The acid anhydride of component (C) may be any compound having one or more acid anhydride groups per molecule that can react with the epoxy groups or hydroxyl groups of component (A) or component (D), and among these, carboxylic acid anhydrides are preferred. Examples of carboxylic acid anhydrides include phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, methylnadic acid, hydrogenated methylnadic acid, trialkyltetrahydrophthalic anhydride, octenylsuccinic anhydride, tetrapropenylsuccinic anhydride, pyromellitic dianhydride, 4,4'-oxydiphthalic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,2'-dimethyl-3,3',4,4'-biphenyltetracarboxylic dianhydride, 5,5'-dimethyl-3,3',4,4'-biphenyltetracarboxylic dianhydride, 1,2,3,4-butanetetracarboxylic dianhydride, and methylcyclohexenetetracarboxylic dianhydride. Among these, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, and hydrogenated methylnadic acid are preferred because they suppress volatilization during the production of molding materials and allow the epoxy resin composition to easily impregnate reinforcing fibers.

[0036] Examples of commercially available acid anhydrides include "RIKACID (registered trademark)" MH-700, "RIKACID (registered trademark)" MH-700G, "RIKACID (registered trademark)" MH, "RIKACID (registered trademark)" MH-T, "RIKACID (registered trademark)" MTA-15, "RIKACID (registered trademark)" OSA, "RIKACID (registered trademark)" DDSA, "RIKACID (registered trademark)" HNA-100, "RIKACID (registered trademark)" TH, "RIKACID (registered trademark)" HH, "RIKACID (registered trademark)" SA, "RIKACID (registered trademark)" BT-100, "RIKACID (registered trademark)" TDA-100 (all manufactured by New Japan Chemical Co., Ltd.), HN-2200, HN-2000, HN-5500, MHAC-P (all manufactured by Hitachi Chemical Co., Ltd.), and the like.

[0037] In order to further improve the heat resistance of the fiber-reinforced composite material, it is more preferable to include an isocyanate compound as component (C).

[0038] The isocyanate compound of component (C) may be any compound having one or more isocyanate groups in one molecule, and known aliphatic isocyanates and aromatic isocyanates can be used.

[0039] Examples of isocyanate compounds include ethylene diisocyanate, trimethylene diisocyanate, dodecamethylene diisocyanate, hexamethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, propylene-1,2-diisocyanate, 2,3-dimethyltetramethylene diisocyanate, butylene-1,2-diisocyanate, butylene-1,3-diisocyanate, 1,4-diisocyanate hexane, cyclopentene-1,3-diisocyanate, isophorone diisocyanate, 1,2,3,4-tetraisocyanate butane, and butane-1,2,3-. Examples of suitable isocyanates include aromatic isocyanates such as triisocyanate, p-phenylene diisocyanate, 1-methylphenylene-2,4-diisocyanate, naphthalene-1,4-diisocyanate, tolylene diisocyanate, diphenyl-4,4-diisocyanate, benzene-1,2,4-triisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate (MDI), diphenylpropane diisocyanate, tetramethylene xylene diisocyanate, and polymethylene polyphenyl polyisocyanate, as well as those having a structure in which these aromatic isocyanates are linked via methylene groups, etc. Among these, aromatic isocyanates are preferred because of the excellent heat resistance of the epoxy resin cured product.

[0040] Alternatively, a prepolymer obtained by prepolymerizing these polyisocyanate compounds with a polyol compound may be used.These polyisocyanate compounds may be used alone or in combination of two or more.

[0041] Commercially available isocyanates include, for example, Duranate (registered trademark) D101 and Duranate (registered trademark) D201 (all manufactured by Asahi Kasei Corporation), Lupranate (registered trademark) MS, Lupranate (registered trademark) MI, Lupranate (registered trademark) M20S, Lupranate (registered trademark) M11S, Lupranate (registered trademark) M5S, Lupranate (registered trademark) T-80, Lupranate (registered trademark) MM-103, Lupranate (registered trademark) MP-102, and Lupranate (registered trademark) MB-301 (all manufactured by BASF INOAC). Polyurethanes Co., Ltd.), HDI, "Millionate (registered trademark)" MR-100, "Millionate (registered trademark)" MR-200, "Millionate (registered trademark)" MR-400, "Coronate (registered trademark)" T-80, "Coronate (registered trademark)" T-65, "Coronate (registered trademark)" T-100 (all manufactured by Tosoh Corporation), "Cosmonate (registered trademark)" PH, "Cosmonate (registered trademark)" T-80, "Takenate (registered trademark)" 500, "Takenate (registered trademark)" 600, "NBID (registered trademark)" Nor Examples of such an alkyl acrylate include bornane diisocyanate, Millionate (registered trademark) MTL, Cosmonate (registered trademark) LL, Cosmonate (registered trademark) LK, Cosmonate (registered trademark) LT, Cosmonate (registered trademark) LI (manufactured by Mitsui Chemicals, Inc.), Sumidur (registered trademark) N3300, Desmodur (registered trademark) N3400 (all manufactured by Sumika Covestro Urethane Co., Ltd.), Desmodur (registered trademark) I, and Desmodur (registered trademark) W (all manufactured by Sumika Covestro Urethane Co., Ltd.).

[0042] When an acid anhydride and an isocyanate are used in combination as component (C), both ester and urethane bonds can be introduced into the polymer skeleton formed by reaction with epoxy or hydroxyl groups. This is preferable because it facilitates hydrogen bond formation and further suppresses volatilization of the components.

[0043] The viscosity of component (C) at 25°C is preferably 1 mPa·s or more and 1000 mPa·s or less. A viscosity of 1 mPa·s or more is preferred because the molding material is less likely to volatilize during production, molding, and long-term storage, while a viscosity of 1000 mPa·s or less is preferred because the molding material exhibits appropriate tackiness.

[0044] The epoxy resin composition of the present invention satisfies the following formula (1). 0.14≦Wc / Wb≦2.00 …(1) Here, Wb: Number of moles of active hydrogen in component (B) Wc: Number of moles of component (C).

[0045] By ensuring that the Wc / Wb ratio is 0.14 or higher, and preferably 0.20 or higher, the acid anhydride groups and / or isocyanate groups in component (C) prevent the active hydrogen in component (B) from reacting with the epoxy groups during storage, allowing the composition to maintain good tackiness even after long-term storage. Furthermore, by ensuring that the Wc / Wb ratio is 2.00 or lower, and preferably 0.80 or lower, there is sufficient active hydrogen in component (B) capable of forming hydrogen bonds with oxygen atoms on the acid anhydride groups and / or isocyanate groups, preventing components from volatilizing from the uncured epoxy resin composition.

[0046] The content of component (C) is preferably 1 part by mass or more and 40 parts by mass or less, based on 100 parts by mass of all epoxy resin components in the epoxy resin composition. By using an amount of 1 part by mass or more, more preferably 10 parts by mass or more, and even more preferably 15 parts by mass or more, the molding material can exhibit excellent tackiness. Furthermore, by using an amount of 40 parts by mass or less, more preferably 35 parts by mass or less, volatilization of the components can be suppressed during production of the molding material, during molding, and during long-term storage.

[0047] (Component (D)) In the molding material of the present invention, the epoxy resin composition preferably further contains, as component (D), a bisphenol-type epoxy resin having a number-average molecular weight of 366 or more and 1000 or less. Such component (D) contributes to more precise control of the tackiness of the molding material.

[0048] In the molecular weight distribution for measuring the number average molecular weight, if there is a peak outside the above range and a valley due to overlap with the base of the peak, the point where the minimum value is obtained in the valley is used as the cutoff point.

[0049] When the number average molecular weight of component (D) is 366 or more, the heat resistance of the fiber-reinforced composite material is superior. Furthermore, when the number average molecular weight is 1000 or less, preferably 800 or less, the cured product of the epoxy resin composition can exhibit excellent bending distortion properties.

[0050] Examples of component (D) include bisphenol A epoxy resins, bisphenol F epoxy resins, and epoxy resins modified with these. Two or more of these may be used in combination. Among these, bisphenol A epoxy resins are preferred because they provide excellent bending strain properties to the cured product of the epoxy resin composition.

[0051] Commercially available bisphenol A type epoxy resins include "jER (registered trademark)" 825, "jER (registered trademark)" 826, "jER (registered trademark)" 827, "jER (registered trademark)" 828, "jER (registered trademark)" 834, "jER (registered trademark)" 1001, "jER (registered trademark)" 1002, "jER (registered trademark)" 1003, "jER (registered trademark)" 1004, and "jER (registered trademark)" 1005. Examples of suitable ethylene glycol acrylates include "jER (registered trademark)" 1004AF, "jER (registered trademark)" 1007, and "jER (registered trademark)" 1009 (all manufactured by Mitsubishi Chemical Corporation), "Epiclon (registered trademark)" 850 (manufactured by DIC Corporation), "Epotohto (registered trademark)" YD128 (manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.), "DER (registered trademark)"-331, and "DER (registered trademark)"-332 (manufactured by The Dow Chemical Company).

[0052] Commercially available bisphenol F epoxy resins include jER (registered trademark) 806, jER (registered trademark) 807, jER (registered trademark) 1750, jER (registered trademark) 4004P, jER (registered trademark) 4007P, and jER (registered trademark) 4009P (all manufactured by Mitsubishi Chemical Corporation), Epicron (registered trademark) 830 (manufactured by DIC Corporation), Epotohto (registered trademark) YDF-170, Epotohto (registered trademark) YDF2001, and Epotohto (registered trademark) YDF2004 (all manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.). Commercially available alkyl-substituted tetramethylbisphenol F epoxy resins include Epotohto (registered trademark) YSLV-80XY (manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.).

[0053] Examples of bisphenol S type epoxy resins include "Epiclon (registered trademark)" EXA-1515 (manufactured by DIC Corporation).

[0054] The content of component (D) in the total epoxy resin components in the epoxy resin composition is preferably 10% by mass or more and 70% by mass or less. A mass proportion of component (A) of 10% by mass or more is preferred because sufficient heat resistance can be achieved, and a mass proportion of 70% by mass or less is preferred because sufficient improvement in bending distortion properties can be achieved.

[0055] (Component (E)) The epoxy resin composition of the present invention preferably further contains a compound containing a carboxy group as component (E). Here, the carboxy group is a functional group represented by the chemical formula COOH. Component (E) may also be a compound produced by a reaction of a portion of component (C) with water. Component (E) is a component that forms hydrogen bonds in the system during long-term storage of the molding material, thereby suppressing the volatilization of the components in the molding material. Any known compound containing one or more carboxy groups per molecule can be used.

[0056] Examples of component (E) include carboxylic acids, amino acids, carbamic acids, etc. Among these, carboxylic acids having 7 to 20 carbon atoms are preferred. When the carbon number is 7 or more, hydrogen bonds can be easily formed, and when the carbon number is 20 or less, excellent compatibility with the epoxy resin composition is achieved.

[0057] Examples of carboxylic acids include acetic acid, butyric acid, caproic acid, enanthic acid, lauric acid, myristic acid, palmitic acid, margaric acid, stearic acid, oleic acid, linoleic acid, linolenic acid, sorbic acid, and carboxylic acids obtained by partial hydrolysis of the acid anhydride of component (C). Examples of carbamic acids include carbamic acid, carbamic acid obtained by hydrolyzing a portion of the isocyanate of component (C), etc. These compounds containing a carboxy group may be used alone or in combination of two or more.

[0058] The epoxy resin composition of the present invention preferably satisfies the following formula (2): 1≦(Me / Mc)×100≦90 (2) Mc: Number of moles of component (C) Me: Number of moles of carboxyl groups in component (E) When (Me / Mc) × 100 is 1 or more, the carbonyl groups and isocyanate groups of component (C) and the carboxyl groups of component (E) effectively form hydrogen bonds, further suppressing volatilization of the components. Furthermore, when (Me / Mc) × 100 is 90 or less, more preferably 60 or less, the cured product of the epoxy resin composition can effectively exhibit excellent flexural distortion properties.

[0059] (Component (F)) The epoxy resin composition of the present invention preferably further contains a glycidylamine-type epoxy resin as component (F), which functions to improve the tackiness of the molding material and the heat resistance of the fiber-reinforced composite material.

[0060] Suitable examples of the component (F) include diaminodiphenylmethane type epoxy resins, aminophenol type epoxy resins, diaminodiphenylsulfone type epoxy resins, and xylylenediamine type epoxy resins.

[0061] Commercially available diaminodiphenylmethane epoxy resins include "Sumiepoxy (registered trademark)" ELA434 (manufactured by Sumitomo Chemical Co., Ltd.), YH434L (manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.), "jER (registered trademark)" 604 (manufactured by Mitsubishi Chemical Corporation), "Araldite (registered trademark)" MY720, and "Araldite (registered trademark)" MY721 (all manufactured by Huntsman Advanced Materials).

[0062] Commercially available aminophenol-type epoxy resins include "Sumiepoxy (registered trademark)" ELA100 and "Sumiepoxy (registered trademark)" ELA120 (all manufactured by Sumitomo Chemical Co., Ltd.), "Araldite (registered trademark)" MY0500, "Araldite (registered trademark)" MY0510, and "Araldite (registered trademark)" MY0600 (all manufactured by Huntsman Advanced Materials).

[0063] Commercially available diaminodiphenyl sulfone type epoxy resins include TG3DAS (manufactured by Mitsui Fine Chemicals, Inc.).

[0064] Commercially available xylylenediamine epoxy resins include TETRAD-X (manufactured by Mitsubishi Gas Chemical Company, Inc.).

[0065] The content of component (F) in the total epoxy resin components in the epoxy resin composition is preferably 8% by mass or more and 20% by mass or less. By having a content of 8% by mass or more, the fiber-reinforced composite material can effectively exhibit excellent heat resistance. Furthermore, by having a content of 20% by mass or less, more preferably 15% by mass or less, volatilization of the components during long-term storage of the molding material can be suppressed.

[0066] (Other ingredients) The epoxy resin composition may contain a thermoplastic resin soluble in the epoxy resin, a reactive diluent, particles, or an internal mold release agent for the purposes of adjusting the viscoelasticity, improving the tack and drape properties of the molding material, or enhancing the mechanical properties and toughness of the resin composition, within the range that does not impair the effects of the present invention.

[0067] (thermoplastic resin) Examples of thermoplastic resins soluble in epoxy resins include polyvinyl acetal resins such as polyvinyl formal and polyvinyl butyral, polyvinyl alcohol, phenoxy resin, polyamide, polyimide, polyvinylpyrrolidone, and polysulfone.

[0068] (reactive diluent) As the reactive diluent, an aliphatic epoxy resin is preferred because it can reduce the viscosity of the epoxy resin composition and increase the impregnation ability into the carbon fiber.

[0069] As the monofunctional aliphatic epoxy resin, a glycidyl ether of a monovalent aliphatic alcohol is preferred, and a monovalent one having 4 to 12 carbon atoms in which a hydroxyl group is bonded to a linear or branched hydrocarbon group is more preferred.

[0070] Examples of the monohydric aliphatic alcohol include butyl alcohol, isobutyl alcohol, s-butyl alcohol, 2-ethylhexanol, stearyl alcohol, isostearyl alcohol, and lauryl alcohol.

[0071] The difunctional or higher aliphatic epoxy resin is preferably a polyglycidyl ether of a divalent or higher aliphatic alcohol, more preferably a divalent or higher aliphatic alcohol having 4 to 10 carbon atoms and in which a hydroxyl group is bonded to a linear or branched hydrocarbon group.

[0072] Examples of dihydric or higher aliphatic alcohols include 1,4-butanediol, 3-methyl-1,5-pentanediol, diethylene glycol, neopentyl glycol, 1,6-hexanediol, 1,9-nonanediol, cyclohexanedimethanol, propylene glycol, glycerin, and trimethylolpropane.

[0073] Either monofunctional or di- or higher functional aliphatic epoxy resins may be used, or both may be used. Di- or higher functional aliphatic epoxy resins are particularly preferred because they can reduce the viscosity of the epoxy resin composition without significantly impairing the flexural properties of the fiber-reinforced composite material.

[0074] The aliphatic epoxy resins may be used alone or in combination of two or more.

[0075] In order to achieve a sufficient decrease in viscosity of the epoxy resin composition, the viscosity of the aliphatic epoxy resin at 25°C is preferably 200 mPa·s or less, and more preferably 150 mPa·s or less.

[0076] (particle) Examples of the particles that can be selected include organic particles such as rubber particles and thermoplastic resin particles, inorganic particles such as silica particles, and nanoparticles such as CNTs, graphene, and carbon black. Examples of the rubber particles include crosslinked rubber particles and core-shell rubber particles in which a different polymer is graft-polymerized onto the surface of a crosslinked rubber particle.

[0077] (internal release agent) Examples of internal release agents include metal soaps, vegetable waxes such as polyethylene wax and carnauba wax, ester compounds of fatty acids and fatty alcohols, ester compounds of polycarboxylic acids and fatty alcohols, ester compounds of polyhydric alcohols and fatty acids, fatty alcohols, fatty acid amides, metal salts of fatty acids, silicone oils, animal waxes, and fluorine-based nonionic surfactants.

[0078] Commercially available internal mold release agents include UNT-750 (Marubishi Yuka Kogyo Co., Ltd.) Examples of such additives include WIZ (registered trademark) INT1846 (manufactured by AXEL PLASTICS RESEARCH LABORATORIES INC.), Licowax S, Licowax P, Licowax OP, Licowax PE190, and Licowax PED (manufactured by Clariant Japan K.K.), SL-900A (manufactured by Riken Vitamin Co., Ltd.), and zinc stearate (manufactured by Kawamura Chemical Industries, Ltd.).

[0079] The amount of the internal mold release agent in the epoxy resin composition is preferably 0.1 to 5% by mass, more preferably 0.2 to 2% by mass, in which case the mold release effect from the mold is suitably exhibited.

[0080] The epoxy resin composition of the present invention preferably has a viscosity of 0.1 Pa·s or more and 3.0 Pa·s or less at 25°C as measured with an E-type viscometer. Epoxy resin compositions with a viscosity of 0.1 Pa·s or more at 25°C have excellent impregnation properties into reinforcing fibers. Furthermore, epoxy resin compositions with a viscosity of 3.0 Pa·s or less, more preferably 2.0 Pa·s or less, at 30°C do not have an excessively low viscosity during resin impregnation, making it easier to uniformly impregnate reinforcing fibers. The viscosity is measured for the epoxy resin composition after mixing the components and stirring for 1 minute.

[0081] The epoxy resin composition used in the present invention preferably has a volatilization amount of 0.01% by mass or more and 5.00% by mass or less when heated at 40°C for 24 hours to thicken the composition, and a volatilization amount of 0.01% by mass or more and 5.00% by mass or less when cured at 150°C for 30 minutes. By suppressing the volatilization amount during both thickening and curing of the epoxy resin composition, it is possible to prevent volatile components from remaining inside the fiber-reinforced composite material obtained by curing the molding material. When both volatilization amounts are 0.01% by mass or more, volatilization of components during long-term storage of the molding material is extremely small. Furthermore, when both volatilization amounts are 5.00% by mass or less, more preferably 2.00% by mass or less, the surface smoothness of the fiber-reinforced composite material is improved.

[0082] In the present invention, the amount of volatilization is measured based on VDA 277. Specifically, the amount is measured by a gas chromatograph equipped with a flame ionization detector (GC-FID) using a DB-WAXETR column (manufactured by Agilent Technologies, Inc., length 30 m, inner diameter 0.25 mm, membrane thickness 0.25 μm).

[0083] The epoxy resin composition of the present invention preferably has a volatilization amount of 1 μg / g or more and 100 μg / g or less when the cured product obtained by heating at 150°C for 30 minutes is heated at 120°C for 5 hours. If the volatilization amount is 1 μg / g or more, the volatilization of components during long-term storage of the fiber-reinforced composite material at room temperature, for example, 25°C, is extremely small. Furthermore, if the volatilization amount is 100 μg / g or less, more preferably 50 μg / g or less, the fiber-reinforced composite material is prevented from losing surface smoothness even after long-term storage.

[0084] The epoxy resin composition of the present invention preferably has a bending strain of 3.5% or more when heated at 150°C for 30 minutes and completely cured to form a cured product with a thickness of 2 mm, as determined by a three-point bending test according to JIS K7074. The mechanical properties of the fiber-reinforced composite material of the present invention depend on the mechanical properties of the cured product obtained by curing the epoxy resin composition. If the bending strain of the cured product is 3.5% or more, more preferably 4.0% or more, the fiber-reinforced composite material can be used as an excellent component that will not break even in an environment where it is subjected to strong external stress.

[0085] The epoxy resin composition of the present invention preferably has a glass transition temperature of 120°C or higher and 250°C or lower when heated at 150°C for 30 minutes and completely cured. The heat resistance of a fiber-reinforced composite material obtained using the epoxy resin composition of the present invention depends on the glass transition temperature of the cured resin product obtained by curing the epoxy resin composition. If the glass transition temperature is 120°C or higher, more preferably 130°C or higher, high heat resistance is imparted to the cured resin product obtained by curing the epoxy resin composition. Furthermore, if the glass transition temperature is 250°C or lower, more preferably 220°C or lower, the crosslink density of the three-dimensional crosslinked structure of the cured resin product is not too high, and high mechanical properties are exhibited.

[0086] The glass transition temperature of a cured epoxy resin is determined by measurement using a dynamic viscoelasticity measuring device (DMA). Specifically, a rectangular test piece cut from a cured resin plate is subjected to DMA measurement at elevated temperatures, and the temperature at the inflection point of the resulting storage modulus G' is designated as Tg. The measurement conditions are as described in the Examples.

[0087] (reinforced fiber) Examples of reinforcing fibers in the present invention include glass fibers, carbon fibers, graphite fibers, aramid fibers, boron fibers, alumina fibers, and silicon carbide fibers. Two or more of these reinforcing fibers may be mixed, but carbon fibers and graphite fibers are preferred for obtaining lighter, more durable molded products. In particular, for applications requiring lighter materials and higher strength, carbon fibers are preferred due to their excellent specific modulus and specific strength.

[0088] The tensile modulus of the carbon fiber is preferably 230 GPa or more and 400 GPa or less from the viewpoint of impact resistance.

[0089] The tensile strength of the carbon fiber is preferably 4.4 GPa or more and 6.5 GPa or less, since this allows a composite material having high rigidity and mechanical strength to be obtained.

[0090] The tensile elongation of the carbon fiber is preferably 1.7% or more and 2.3% or less.

[0091] The average fiber diameter of the carbon fibers is preferably 3 μm or more and 12 μm or less.

[0092] Examples of commercially available carbon fibers include "TORAYCA (registered trademark)" T800G-24K, "TORAYCA (registered trademark)" T800S-24K, "TORAYCA (registered trademark)" T700G-24K, "TORAYCA (registered trademark)" T300-3K, and "TORAYCA (registered trademark)" T700S-12K (all manufactured by Toray Industries, Inc.), "PYROFIL (registered trademark)" TR50S-3L, "PYROFIL (registered trademark)" TR50S-6L, "PYROFIL (registered trademark)" TR50S-15L, "PYROFIL (registered trademark)" TRH50-60M, and "PYROFIL (registered trademark)" TRH40-50L (all manufactured by Mitsubishi Chemical Corporation).

[0093] When a continuous reinforcing fiber is used, examples of the fiber structure include long fibers aligned in one direction, a single tow, a woven fabric, a knitted fabric, a nonwoven fabric, a mat, and a braided cord.

[0094] The reinforcing fibers in the present invention are discontinuous reinforcing fibers having a number average fiber length of 3 mm or more and 100 mm or less, and are substantially randomly oriented as bundle aggregates in the molding material. The bulkiness Bm of the bundle aggregates of discontinuous reinforcing fibers calculated by the following formula (3) is 1.5 cm 3 / g or more 5cm 3 / g or less is preferable. Bm=Tm / Fm …(3) Here, Bm: bulkiness (cm 3 / g) Tm: Thickness of the bundle of discontinuous reinforcing fibers (cm) Fm: Mass of discontinuous reinforcing fibers per unit area in the molding material (g / cm 2 ).

[0095] The bulkiness Bm of a bundle of discontinuous reinforcing fibers is a characteristic value determined from the shape (length, width, thickness, straightness, angle, etc.) of the bundle of discontinuous reinforcing fibers and the orientation of the bundle of discontinuous reinforcing fibers in the in-plane direction and out-of-plane (thickness) direction.

[0096] Bulkiness: 1.5cm 3 When the bulkiness is 5 cm / g or more, gaps between and within the bundles of discontinuous reinforcing fibers are secured when the bundled aggregate of discontinuous reinforcing fibers is impregnated with an epoxy resin composition to obtain a molding material, thereby preventing impregnation failure with the epoxy resin composition and effectively obtaining molding materials and fiber-reinforced composite materials of stable quality. 3 / g or less, when the bundle-like aggregate of discontinuous reinforcing fibers is impregnated with an epoxy resin composition to obtain a molding material, the thickness of the bundle-like aggregate of discontinuous reinforcing fibers can be reduced, impregnation failure with the epoxy resin composition can be prevented, and molding materials and fiber-reinforced composite materials of stable quality can be effectively obtained.

[0097] The measurements of Tm and Fm in the above formula are carried out as follows: First, the mass Fm of the reinforcing fibers per unit area in the molding material (fiber basis weight) is measured. Next, the thickness Tm of the bundled aggregate of discontinuous reinforcing fibers is measured using a thickness gauge under the condition of 0.1 kN in accordance with ISO 5084 (1996).

[0098] The number-average fiber length of the bundles of discontinuous reinforcing fibers is preferably 3 mm or more and 100 mm or less. By making it 100 mm or less, it is possible to obtain a molding material that has excellent molding conformability to complex shapes. Furthermore, by making it 3 mm or more, more preferably 5 mm or more, it is possible to effectively obtain the reinforcing effect of the reinforcing fibers.

[0099] The number average fiber length of a bundle of discontinuous reinforcing fibers is measured as follows: 100 bundles of discontinuous reinforcing fibers are randomly selected from an assembly of bundles of discontinuous reinforcing fibers, and the average of measurements taken at three or more points on each bundle of discontinuous reinforcing fibers is calculated. The average of the 100 is taken as the number average fiber length. Measurements are performed on a computer using image processing software.

[0100] The number-average number of filaments in the bundle of discontinuous reinforcing fibers is preferably 500 or more and less than 12,000. When the number-average number of filaments in the bundle of discontinuous reinforcing fibers is 500 or more, the bundle of discontinuous reinforcing fibers is prevented from bending in the longitudinal direction of the fibers during processing to form a fiber-reinforced composite material, thereby maintaining the straightness of the fibers, and the reinforcing effect of the reinforcing fibers when formed into a fiber-reinforced composite material, i.e., improved mechanical properties, particularly strength, can be effectively obtained. On the other hand, when the number-average number of filaments is less than 12,000, stress concentration at the ends of the discontinuous reinforcing fiber bundles is prevented when formed into a fiber-reinforced composite material, thereby suppressing variation in mechanical properties, particularly strength.

[0101] The number-average number of filaments in a bundle of discontinuous reinforcing fibers is measured as follows: After measuring the number-average fiber length, the mass of 100 bundles of discontinuous reinforcing fibers is measured. The number of filaments in one bundle of discontinuous reinforcing fibers is calculated from the fiber length, mass, specific gravity, and fiber diameter. The average of the 100 bundles is taken as the number-average number of filaments.

[0102] The discontinuous reinforcing fiber bundles are preferably substantially randomly oriented. "Substantially randomly oriented" means that when the fiber longitudinal directions of the chopped fiber bundles constituting the bundled assembly of discontinuous reinforcing fibers are classified into four 45° directions (-90°≦θ<-45°, -45°≦θ<0°, 0°≦θ<45°, 45°≦θ<90°) starting from any direction, the proportion of the discontinuous reinforcing fiber bundles oriented in each direction is relatively uniformly distributed within a range of 25±2.5%. Because the discontinuous reinforcing fiber bundles are substantially randomly oriented, a molding material obtained by impregnating a bundled assembly of discontinuous reinforcing fibers with an epoxy resin composition can be handled as an isotropic material, facilitating the design of a fiber-reinforced composite material using the molding material.

[0103] The fiber orientation of discontinuous reinforcing fiber bundles is measured as follows. First, the discontinuous reinforcing fiber bundle is sliced ​​in-plane across the thickness of the bundle so that at least 90% of the discontinuous reinforcing fiber bundles within the measurement area are visible, and an image of the sliced ​​surface is captured. To slice in-plane, an adhesive sheet is applied to the bundle while maintaining the orientation of the discontinuous reinforcing fiber bundles, and the discontinuous reinforcing fibers near the surface of the bundle are transferred to the adhesive sheet. This transferred surface is then photographed. This procedure is repeated for the surface of the bundle updated by slicing, i.e., across the thickness of the bundle. Next, the orientation angle of each discontinuous reinforcing fiber bundle is measured from the obtained image. The orientation angle is measured on a computer using image processing software. A histogram is created from the obtained orientation angle values ​​and classified into four-directional distributions.

[0104] The area of ​​the bundled assembly of discontinuous reinforcing fibers to be measured is 2,000 mm 2 On the other hand, if it is too large, it is not desirable from the viewpoint of aligning the measurement positions for the fiber basis weight and the thickness of the bundled aggregate of discontinuous reinforcing fibers. 2 (100mm x 100mm).

[0105] One method for producing the above-described bundled aggregate of discontinuous reinforcing fibers is to cut a continuous fiber bundle having a filament count in the range of 500 to less than 12,000 in the longitudinal direction of the fibers so that the number average fiber length is in the range of 3 to 100 mm, and then orient the bundled discontinuous reinforcing fibers substantially randomly.

[0106] Other methods include a method in which a continuous fiber bundle having 1000 or more filaments is split into multiple bundles along the fiber longitudinal direction, and then cut in the fiber longitudinal direction so that the number average fiber length is within a range of 3 to 100 mm, and the bundles of discontinuous reinforcing fibers are oriented substantially randomly; a method in which a continuous fiber bundle having 1000 or more filaments is cut in the fiber longitudinal direction so that the number average fiber length is within a range of 3 to 100 mm, and then split into multiple discontinuous reinforcing fiber bundles along the fiber longitudinal direction, and the discontinuous reinforcing fiber bundles are oriented substantially randomly; or a method that combines the above two methods.

[0107] For example, a continuous fiber bundle with 48,000 filaments is split into bundles of 3,000 filaments each (16 equal parts) along the fiber longitudinal direction, and then cut in the fiber longitudinal direction so that the number average fiber length is 25 mm.The bundle of discontinuous reinforcing fibers is then split in half by impact, resulting in a bundle-like assembly of discontinuous reinforcing fibers with a number average filament count of 1,500.

[0108] The content of reinforcing fibers in the molding material of the present invention is 30% by mass or less and 90% by mass or less. If the mass fraction of reinforcing fibers is 30% by mass or more, the mass of the obtained fiber-reinforced composite material does not become excessively large, and the advantages of the fiber-reinforced composite material, such as excellent specific strength and specific modulus, can be fully exhibited. Furthermore, if the mass fraction of reinforcing fibers is 90% by mass or less, the impregnation of the epoxy resin composition into the reinforcing fibers is excellent.

[0109] Examples of molding materials obtained using continuous reinforcing fibers include prepregs and towpregs.

[0110] Examples of molding materials obtained using discontinuous reinforcing fibers include bulk molding compounds (BMCs) and sheet molding compounds (SMCs). Of these, SMCs are particularly preferred from the viewpoints of productivity and freedom in the shape of molded articles.

[0111] The molding material of the present invention is preferably in the form of a sheet.

[0112] The molding material weight is 500g / m 2 More than 2500g / m 2 The weight of the molding material is preferably 500 g / m or less. 2 If the density is 2500 g / m or more, the number of laminated sheets when molding the molding material can be reduced, leading to improved production efficiency of fiber reinforced composite materials. 2 If the ratio is less than or equal to 1, the epoxy resin composition will have excellent impregnation ability into the reinforcing fibers when producing a molding material.

[0113] The molding material of the present invention maintains stable tackiness and fluidity during press molding even after long-term storage of 30 days or more, and a fiber-reinforced composite material with excellent surface smoothness and mechanical properties can be obtained.

[0114] The fiber-reinforced composite material of the present invention is obtained by curing the molding material of the present invention.

[0115] In the fiber-reinforced composite material of the present invention, the cured product of the epoxy resin matrix resin preferably has a glass transition temperature of 120°C or higher and 250°C or lower. Such a glass transition temperature within this range results in excellent heat resistance. Furthermore, in the fiber-reinforced composite material of the present invention, the cured product of the epoxy resin matrix resin preferably has a bending strain of 3.5% or higher. Such a bending strain of 3.5% or higher results in excellent mechanical properties. Particularly in the aircraft and automotive fields, fiber-reinforced composite materials are required to have high heat resistance and mechanical properties such as bending strain.

[0116] Suitable methods for producing the fiber-reinforced composite material of the present invention include hand lay-up, filament winding, pultrusion, resin transfer molding (RTM), autoclave molding of prepregs, and press molding of molding materials for fiber-reinforced composite materials such as prepregs, towpregs, bulk molding compounds (BMC), and sheet molding compounds (SMC). [Example]

[0117] The molding material and fiber-reinforced composite material of the present invention will be described in more detail below with reference to examples.

[0118] <Measurement and evaluation methods, and preparation of measurement samples> (1) Viscosity of epoxy resin composition at 25°C Immediately after preparation, the epoxy resin composition was measured at 25°C using an E-type viscometer equipped with a standard cone rotor (cone angle 1°34', cone radius 24 mm) in accordance with the "Viscosity measurement method using a cone-plate rotational viscometer" in JIS Z8803 (1991). The E-type viscometer used was a TVE-30H manufactured by Tokimec Inc.

[0119] (2) Volatilization amount when the resin composition thickens 5.0 g of the prepared epoxy resin composition was spread thinly on an aluminum cup to a thickness of 0.2 mm or less and heated at 40°C for 24 hours. The mass before and after heating was measured with an accuracy of 0.001 g, and the change was divided by the mass of the original epoxy resin composition to calculate the amount of volatilization during thickening. The amount of volatilization during thickening was taken as the average value of the volatilization amounts obtained from three samples.

[0120] (3) Volatilization amount of resin composition during curing 5.0 g of the thickened epoxy resin composition obtained in (2) above was placed in an aluminum cup and heated at 150°C for 30 minutes. The mass before and after heating was measured with an accuracy of 0.001 g, and the change was divided by the mass of the original epoxy resin composition to calculate the amount of volatilization of the thickened product. The amount of volatilization during thickening was taken as the average value of the amounts of volatilization obtained from three samples.

[0121] (4) Preparation of a cured resin composition The prepared epoxy resin composition was degassed in a vacuum and then poured into a mold set to a thickness of 2 mm using a 2 mm Teflon (registered trademark) spacer. It was then heated at 150°C for 30 minutes to cure, yielding a 2 mm thick cured resin.

[0122] (5) Volatilization amount of the cured resin composition 2,000 g of the cured product prepared in (4) above was weighed into a 20 mL headspace vial and heated at 120°C for 5 hours. The gas phase after heating was analyzed using a gas chromatograph with a flame ionization detector (GC-FID) in accordance with VDA 277 to measure the amount of volatilization of the cured product. The amount of volatilization of the cured product was expressed as the ratio of the measured amount of volatilization to the weighed mass of the cured product (unit: μg / g), and was taken as the average value of the volatilization amounts obtained from three samples.

[0123] (6) Bending strain of the cured product 30 days after curing The cured product prepared in (4) above was stored at 25°C for 30 days. After storage, test pieces measuring 10 mm wide and 600 mm long were cut from the samples, and the maximum bending deflection was measured by a three-point bending test using an Instron universal testing machine (manufactured by Instron Corporation) in accordance with JIS K7074:1988. The measurement conditions were a crosshead speed of 5 mm / min, a span of 80 mm, a thickness of 5 mm, and a support diameter of 2 mm. The measured values ​​of the maximum bending deflection of five samples were calculated and converted to bending strain using the following formula (4): ε=600hw / L 2 …(4) ε: Bending strain (%) h: test piece thickness (mm) w: Maximum bending deflection (mm) L: Span (mm).

[0124] (7) Tackiness of molding material 30 days after production A 10 cm x 10 cm sample was cut out from the molding material. It was then stored in this state at 25°C for 30 days. After storage, the release film was peeled off from the sample at room temperature, the mass of the peeled release film was measured, and the amount of peeling was calculated using the following formula. Peeling amount (%) = [(La-L0) / L0] x 100 La: Mass of release film after peeling L0: The mass of the release film used to produce the molding material, the same size as the release film after peeling.

[0125] The peeling amount was evaluated according to the following criteria. A: The amount of peeling is less than 3%. B: The amount of peeling is 3% or more and less than 5%. C: The amount of peeling is 5% or more.

[0126] (8) Fluidity of molding material 30 days after the date of manufacture The molding material was stored at 25°C for 30 days. Two specimens measuring 5 cm long and 5 cm wide were cut from the stored molding material and laminated in two layers to prepare a sample. After measuring the area of ​​the sample, the sample was heated in a press at a mold temperature of 150°C and a pressure of 20 kN for 5 minutes to produce a fiber-reinforced composite material. The area of ​​the heated sample was measured, divided by the area before press molding, and multiplied by 100 to calculate the flow rate.

[0127] The fluidity was evaluated according to the following criteria. A: Fluidity is 251~600%. B: Fluidity is 111 to 250%. C: The flow rate is 100-110%.

[0128] (9) Surface smoothness of fiber-reinforced composite materials The prepared flat fiber-reinforced composite material was stored at 180°C for 2 hours. After storage, five test pieces (10 pieces in total) measuring 80 mm in length, 30 mm in width, and 1.6 mm in thickness were cut from the fiber-reinforced composite material at 0° and 90° from the longitudinal direction of the plate, with the 0° direction being the 0° direction. The arithmetic mean roughness of the surface of each test piece was measured using a surface roughness measuring device ("Surfcom" 480A, manufactured by Tokyo Seimitsu Co., Ltd.), and the average value of the 10 pieces was used as Ra. The measurement conditions were a crosshead speed of 0.3 mm / s.

[0129] The evaluation was made according to the following criteria according to Ra. A: Ra is 0.25 μm or less. B: Ra is more than 0.25 μm and not more than 0.50 μm. C: Ra is greater than 0.50 μm.

[0130] <Resin raw materials> The following resin raw materials were used to obtain the epoxy resin compositions of each Example and Comparative Example. The numerical values ​​for each component in the "epoxy resin composition" column in the tables indicate the content, and the unit ("parts") is "parts by mass" unless otherwise specified. The tables also list the compound name, trade name, and product number (e.g., "jER806"), or just the product number (e.g., "YDF170").

[0131] (1) Component (A): Bisphenol-type epoxy resin having a number average molecular weight of 250 or more and 365 or less "Epotohto (registered trademark)" YDF170 (manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.): liquid bisphenol F type epoxy resin (number average molecular weight: 340) jER (registered trademark) 806 (Mitsubishi Chemical Corporation): Liquid bisphenol F epoxy resin (number average molecular weight: 330) jER (registered trademark) 825 (manufactured by Mitsubishi Chemical Corporation): liquid bisphenol A type epoxy resin (number average molecular weight: 364).

[0132] (2) Component (B): Latent hardener "jER Cure (registered trademark)" DICY7 (manufactured by Mitsubishi Chemical Corporation): dicyandiamide "Curezol (registered trademark)" 2MZA-PW (manufactured by Shikoku Chemicals Co., Ltd.): 2,4-diamino-6-[2'-methylimidazolyl-(1')-ethyl]-triazine.

[0133] (3) Component (C): Acid anhydride and / or isocyanate compound HN-2200 (Hitachi Chemical Co., Ltd.): Methyltetrahydrophthalic anhydride Lupranate® M20S (manufactured by BASF INOAC Polyurethanes Co., Ltd.): Polymeric MDI (polymethylene polyphenyl polyisocyanate) Lupranate® MM-103 (manufactured by BASF INOAC Polyurethanes Co., Ltd.): Carbodiimide-modified MDI "Desmodur (registered trademark)" I (manufactured by Sumika Covestro Urethane Co., Ltd.): isophorone diisocyanate.

[0134] (4) Component (D): a bisphenol-type epoxy resin having a number average molecular weight of 366 or more and 1,000 or less "Epotohto (registered trademark)" YD128 (manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.): liquid bisphenol A type epoxy resin (number average molecular weight: 378) jER (registered trademark) 1001 (manufactured by Mitsubishi Chemical Corporation): solid bisphenol A type epoxy resin (number average molecular weight: 950).

[0135] (5) Component (E): Compound containing a carboxy group Stearic acid (Tokyo Chemical Industry Co., Ltd.): stearic acid 4-Methyl-1,2,3,6-tetrahydrophthalic acid: A compound obtained by adding the same number of moles of water as the acid anhydride of HN-2200 (manufactured by Hitachi Chemical Co., Ltd.) and heating at 80°C for 1 hour.

[0136] (6) Component (F): Glycidylamine epoxy resin TETRAD-X (Mitsubishi Gas Chemical Co., Inc.): Xylylenediamine epoxy resin · "Araldite (registered trademark)" MY0500 (manufactured by Huntsman Advanced Materials): Aminophenol type epoxy resin.

[0137] (7) Other ingredients QSR-10 (Shin-Etsu Chemical Co., Ltd.) silica particles (average particle size 15 nm).

[0138] [Examples 1 to 33] (Preparation of Epoxy Resin Composition) Epoxy resin compositions were prepared by mixing the components in the mass ratios shown in Tables 1 to 3. When the molecular weight distributions of the mixed epoxy resins in the following Examples and Comparative Examples were examined, no overlapping of the bases of the different components (peaks) was observed. The viscosity at 25°C was good, at 3.0 Pa·s or less. The amount of volatilization during thickening was 5% by mass or less in all cases. The amount of volatilization during curing was 5% by mass or less in all cases. The amount of volatilization of the cured products was 100 μg / g or less in all cases, and the bending strain of the cured products 30 days after curing was 3.5% or more in all cases.

[0139] (Production of bundled aggregates of discontinuous reinforcing fibers) The carbon fiber used was "Torayca (registered trademark)" T700S-12K (manufactured by Toray Industries, Inc.). A continuous fiber bundle of this carbon fiber with 12,000 filaments was widened to a width of 20 mm, and then split into four equal parts in the width direction using a splitting means set in parallel at equal intervals of 5 mm to obtain a continuous carbon fiber strand.

[0140] The 50 bobbins wound with the continuous carbon fiber strands were placed on a creel, and the fiber bundles were unwound from the outer end of the bobbin. The strands were continuously inserted into a rotary strand cutter perpendicular to the longitudinal direction of the fiber bundle and spaced 25 mm apart to cut the fiber bundles and scatter them uniformly to obtain a bundle-like assembly of discontinuous reinforcing fibers with isotropic fiber orientation. The bulkiness of the resulting bundle-like assembly of discontinuous reinforcing fibers was 3.0 cm. 3 / g.

[0141] (Preparation of molding material) The above epoxy resin composition was applied to a release film (Crocodile Brand Transparent Poly Sheet #150 (manufactured by Nihon University Industrial Co., Ltd.)) so as to obtain the reinforcing fiber content and basis weight shown in Tables 1 to 3, and a bundle-like aggregate of discontinuous reinforcing fibers was sandwiched between the film and the epoxy resin composition was impregnated with a roller to produce a molding material.

[0142] Both the tackiness and flow rate 30 days after the production date were B or higher.

[0143] (Fabrication of fiber-reinforced composite materials) Two sheets of the molding material prepared above were stacked on top of each other and pressed under a pressure of 10 MPa using a pressure press. The mixture was heated at 150°C for 10 minutes to obtain a flat plate-shaped fiber-reinforced composite material measuring 300 mm in length, 400 mm in width and 1.6 mm in thickness.

[0144] The surface smoothness of the obtained fiber reinforced composite materials after high temperature treatment was B or higher.

[0145] [Example 34] (Preparation of Epoxy Resin Composition) An epoxy resin composition was prepared by mixing the components in the mass ratios shown in Table 3. The viscosity at 25°C was good, at 3.0 Pa·s or less. The volatilization amount during thickening was 5 mass% or less. The volatilization amount during curing was 5 mass% or less. The volatilization amount of the cured product was 100 μg / g or less, and the bending strain of the cured product 30 days after curing was 3.5% or more.

[0146] (Production of bundled aggregates of discontinuous reinforcing fibers) A bundle-like aggregate of discontinuous reinforcing fibers with isotropic fiber orientation was obtained in the same manner as in Example 1, except that the continuous fiber bundle of carbon fiber was split into two equal parts in the width direction using a splitting processing means set in parallel at equal intervals of 10 mm. The bulkiness of the resulting discontinuous reinforcing fiber was 2.0 cm. 3 / g.

[0147] (Preparation of molding material) The epoxy resin composition was applied to a release film (Crocodile Brand Transparent Poly Sheet #150 (manufactured by Nihon University Industrial Co., Ltd.)) so as to obtain the reinforcing fiber content and basis weight shown in Table 3, and a bundle-like aggregate of discontinuous reinforcing fibers was sandwiched between the film and the composition, followed by impregnation with a roller to produce a molding material.

[0148] Both the tackiness and flow rate 30 days after the production date were B or higher.

[0149] (Fabrication of fiber-reinforced composite materials) A flat plate-shaped fiber-reinforced composite material measuring 300 mm in length, 400 mm in width and 1.6 mm in thickness was obtained in the same manner as in Example 1, except that the above molding material was used.

[0150] The surface smoothness of the obtained fiber-reinforced composite material after high-temperature treatment was B or higher.

[0151] [Example 35] (Preparation of Epoxy Resin Composition) An epoxy resin composition was prepared by mixing the components in the mass ratios shown in Table 3. The properties of the obtained epoxy resin composition were the same as those of Example 34.

[0152] (Production of bundled aggregates of discontinuous reinforcing fibers) A bundle-shaped aggregate of discontinuous reinforcing fibers with isotropic fiber orientation was obtained in the same manner as in Example 1, except that the cutting means for the split fiber bundles was a strand cutter with 3.3 mm intervals and the cutting speed was 1.5 times faster. The bulkiness of the resulting discontinuous reinforcing fibers was 4.0 cm. 3 / g.

[0153] (Preparation of molding material) The epoxy resin composition was applied to a release film (Crocodile Brand Transparent Poly Sheet #150 (manufactured by Nihon University Industrial Co., Ltd.)) so as to obtain the reinforcing fiber content and basis weight shown in Table 3, and a bundle-like aggregate of discontinuous reinforcing fibers was sandwiched between the film and the composition, followed by impregnation with a roller to produce a molding material.

[0154] Both the tackiness and flow rate 30 days after the production date were B or higher.

[0155] (Fabrication of fiber-reinforced composite materials) A flat plate-shaped fiber-reinforced composite material measuring 300 mm in length, 400 mm in width and 1.6 mm in thickness was obtained in the same manner as in Example 1, except that the above molding material was used.

[0156] The surface smoothness of the obtained fiber-reinforced composite material after high-temperature treatment was B or higher.

[0157] [Table 1]

[0158] [Table 2]

[0159] [Table 3]

[0160] [Comparative Example 1] (Preparation of Epoxy Resin Composition) An epoxy resin composition was prepared by mixing the components in the mass ratios shown in Table 4. The viscosity at 25°C was 1.5 Pa·s, which was good. The volatilization amount during thickening was 5 mass% or less. The volatilization amount during curing was 5 mass% or less. The volatilization amount of the cured product was poor, at 108 μg / g, and the bending strain of the cured product 30 days after curing was poor, at 2.7%.

[0161] (Production of bundled aggregates of discontinuous reinforcing fibers) In the same manner as in Example 1, a bundle-shaped assembly of discontinuous reinforcing fibers with isotropic fiber orientation was obtained.

[0162] (Preparation of molding material) The epoxy resin composition was applied to a release film (Crocodile Brand Transparent Poly Sheet #150 (manufactured by Nihon University Industrial Co., Ltd.)) so as to obtain the reinforcing fiber content and basis weight shown in Table 4, and a bundle-like aggregate of discontinuous reinforcing fibers was sandwiched between the film and the composition, followed by impregnation with a roller to produce a molding material.

[0163] The tackiness and flow rate were both C after 30 days from the date of manufacture.

[0164] (Fabrication of fiber-reinforced composite materials) A flat plate-shaped fiber-reinforced composite material measuring 300 mm in length, 400 mm in width and 1.6 mm in thickness was obtained in the same manner as in Example 1, except that the above molding material was used.

[0165] The surface smoothness of the obtained fiber-reinforced composite material after high-temperature treatment was C.

[0166] Comparative Example 2 (Preparation of Epoxy Resin Composition) An epoxy resin composition was prepared by mixing the components in the mass ratios shown in Table 4. The viscosity at 25°C was 4.2 Pa·s, which was poor. The volatilization amount during thickening was 5 mass% or less. The volatilization amount during curing was 5 mass% or less. The volatilization amount of the cured product was 100 μg / g or less, and the bending strain of the cured product 30 days after curing was 3.8%, which was good.

[0167] (Production of bundled aggregates of discontinuous reinforcing fibers) In the same manner as in Example 1, a bundle-shaped assembly of discontinuous reinforcing fibers with isotropic fiber orientation was obtained.

[0168] (Preparation of molding material) The epoxy resin composition was applied to a release film (Crocodile Brand Transparent Poly Sheet #150 (manufactured by Nihon University Industrial Co., Ltd.)) so as to obtain the reinforcing fiber content and basis weight shown in Table 4, and a bundle-like aggregate of discontinuous reinforcing fibers was sandwiched between the film and the composition, followed by impregnation with a roller to produce a molding material.

[0169] Thirty days after the production date, both the tackiness and the flow rate were graded as C, which was poor.

[0170] (Fabrication of fiber-reinforced composite materials) A flat plate-shaped fiber-reinforced composite material measuring 300 mm in length, 400 mm in width and 1.6 mm in thickness was obtained in the same manner as in Example 1, except that the above molding material was used.

[0171] The surface smoothness of the obtained fiber-reinforced composite material after high-temperature treatment was C.

[0172] Comparative Example 3 (Preparation of Epoxy Resin Composition) An epoxy resin composition was prepared by mixing the components in the mass ratios shown in Table 4. The viscosity at 25°C was a good 0.8 Pa·s. The volatilization amount during thickening was 5 mass% or less. The volatilization amount during curing was 5 mass% or less. The volatilization amount of the cured product was 100 μg / g or less, and the bending strain of the cured product 30 days after curing was 3.9%, which was good.

[0173] (Production of bundled aggregates of discontinuous reinforcing fibers) In the same manner as in Example 1, a bundle-shaped assembly of discontinuous reinforcing fibers with isotropic fiber orientation was obtained.

[0174] (Preparation of molding material) The epoxy resin composition was applied to a release film (Crocodile Brand Transparent Poly Sheet #150 (manufactured by Nihon University Industrial Co., Ltd.)) so as to obtain the reinforcing fiber content and basis weight shown in Table 4, and a bundle-like aggregate of discontinuous reinforcing fibers was sandwiched between the film and the composition, followed by impregnation with a roller to produce a molding material.

[0175] Thirty days after the production date, both the tackiness and the flow rate were graded as C, which was poor.

[0176] (Fabrication of fiber-reinforced composite materials) A flat plate-shaped fiber-reinforced composite material measuring 300 mm in length, 400 mm in width and 1.6 mm in thickness was obtained in the same manner as in Example 1, except that the above molding material was used.

[0177] The surface smoothness of the obtained fiber-reinforced composite material after high-temperature treatment was C.

[0178] Comparative Example 4 (Preparation of Epoxy Resin Composition) An epoxy resin composition was prepared by mixing the components in the mass ratios shown in Table 4. The viscosity at 25°C was a good 0.8 Pa·s. The volatilization amount during thickening was 5 mass% or less. The volatilization amount during curing was 5 mass% or less. The volatilization amount of the cured product was 100 μg / g or less, and the bending strain of the cured product 30 days after curing was 3.9%, which was good.

[0179] (Production of bundled aggregates of discontinuous reinforcing fibers) In the same manner as in Example 1, a bundle-shaped assembly of discontinuous reinforcing fibers with isotropic fiber orientation was obtained.

[0180] (Preparation of molding material) The epoxy resin composition was applied to a release film (Crocodile Brand Transparent Poly Sheet #150 (manufactured by Nihon University Industrial Co., Ltd.)) so as to obtain the reinforcing fiber content and basis weight shown in Table 4, and a bundle-like aggregate of discontinuous reinforcing fibers was sandwiched between the film and the composition, followed by impregnation with a roller to produce a molding material.

[0181] Thirty days after the production date, both the tackiness and the flow rate were graded as C, which was poor.

[0182] (Fabrication of fiber-reinforced composite materials) A flat plate-shaped fiber-reinforced composite material measuring 300 mm in length, 400 mm in width and 1.6 mm in thickness was obtained in the same manner as in Example 1, except that the above molding material was used.

[0183] The surface smoothness of the obtained fiber-reinforced composite material after high-temperature treatment was C.

[0184] Comparative Example 5 (Preparation of Epoxy Resin Composition) An epoxy resin composition was prepared by mixing the components in the mass ratios shown in Table 4. The viscosity at 25°C was 5.2 Pa·s, which was poor. The volatilization amount during thickening was 5 mass% or less. The volatilization amount during curing was 5 mass% or less. The volatilization amount of the cured product was 100 μg / g or less, and the bending strain of the cured product 30 days after curing was 5.3%, which was good.

[0185] (Production of bundled aggregates of discontinuous reinforcing fibers) In the same manner as in Example 1, a bundle-shaped assembly of discontinuous reinforcing fibers with isotropic fiber orientation was obtained.

[0186] (Preparation of molding material) The epoxy resin composition was applied to a release film (Crocodile Brand Transparent Poly Sheet #150 (manufactured by Nihon University Industrial Co., Ltd.)) so as to obtain the reinforcing fiber content and basis weight shown in Table 4, and a bundle-like aggregate of discontinuous reinforcing fibers was sandwiched between the film and the composition, followed by impregnation with a roller to produce a molding material.

[0187] Thirty days after the production date, both the tackiness and the flow rate were graded as C, which was poor.

[0188] (Fabrication of fiber-reinforced composite materials) A flat plate-shaped fiber-reinforced composite material measuring 300 mm in length, 400 mm in width and 1.6 mm in thickness was obtained in the same manner as in Example 1, except that the above molding material was used.

[0189] The surface smoothness of the obtained fiber-reinforced composite material after high-temperature treatment was C.

[0190] Comparative Example 6 (Preparation of Epoxy Resin Composition) An epoxy resin composition was prepared by mixing the components in the mass ratios shown in Table 4. The viscosity at 25°C was 3.2 Pa·s, which was poor. The volatilization amount during thickening was 5% by mass or less. The volatilization amount during curing was 5% by mass or less. The volatilization amount of the cured product was 130 μg / g, which was poor, and the bending strain of the cured product 30 days after curing was 2.4%, which was poor.

[0191] (Production of bundled aggregates of discontinuous reinforcing fibers) In the same manner as in Example 1, a bundle-shaped assembly of discontinuous reinforcing fibers with isotropic fiber orientation was obtained.

[0192] (Preparation of molding material) The epoxy resin composition was applied to a release film (Crocodile Brand Transparent Poly Sheet #150 (manufactured by Nihon University Industrial Co., Ltd.)) so as to obtain the reinforcing fiber content and basis weight shown in Table 4, and a bundle-like aggregate of discontinuous reinforcing fibers was sandwiched between the film and the composition, followed by impregnation with a roller to produce a molding material.

[0193] Thirty days after the production date, both the tackiness and the flow rate were graded as C, which was poor.

[0194] (Fabrication of fiber-reinforced composite materials) A flat plate-shaped fiber-reinforced composite material measuring 300 mm in length, 400 mm in width and 1.6 mm in thickness was obtained in the same manner as in Example 1, except that the above molding material was used.

[0195] The surface smoothness of the obtained fiber-reinforced composite material after high-temperature treatment was C.

[0196] Comparative Example 7 (Preparation of Epoxy Resin Composition) An epoxy resin composition was prepared by mixing the components in the mass ratios shown in Table 4. The viscosity at 25°C was 4.4 Pa·s, which was poor. The volatilization amount during thickening was 5 mass% or less. The volatilization amount during curing was 5 mass% or less. The volatilization amount of the cured product was good at 87 μg / g, and the bending strain of the cured product 30 days after curing was 2.8%, which was poor.

[0197] (Production of continuous carbon fiber strands) In the same manner as in Example 1, a bundle-shaped assembly of discontinuous reinforcing fibers with isotropic fiber orientation was obtained.

[0198] (Preparation of molding material) The epoxy resin composition was applied to a release film (Crocodile Brand Transparent Poly Sheet #150 (manufactured by Nihon University Industrial Co., Ltd.)) so as to obtain the reinforcing fiber content and basis weight shown in Table 4, and a bundle-like aggregate of discontinuous reinforcing fibers was sandwiched between the film and the composition, followed by impregnation with a roller to produce a molding material.

[0199] Thirty days after the production date, both the tackiness and the flow rate were graded as C, which was poor.

[0200] (Fabrication of fiber-reinforced composite materials) A flat plate-shaped fiber-reinforced composite material measuring 300 mm in length, 400 mm in width and 1.6 mm in thickness was obtained in the same manner as in Example 1, except that the above molding material was used.

[0201] The surface smoothness of the obtained fiber-reinforced composite material after high-temperature treatment was C.

[0202] [Table 4] [Industrial Applicability]

[0203] The molding material of the present invention is superior to conventional molding materials in that some components do not volatilize even when stored for long periods of time (30 days or more), and the molding material's tackiness and fluidity during press molding are stable. Furthermore, the use of this molding material makes it possible to provide fiber-reinforced composite materials that have excellent surface smoothness and mechanical properties even when processed at high temperatures. This makes the material suitable for use in aerospace and automotive applications, as well as sports and industrial applications in general.

Claims

1. A molding material containing an epoxy resin composition containing the following components (A) to (C) and reinforcing fibers, wherein the content of the reinforcing fibers in the molding material is 30% by mass or more and 90% by mass or less, the content of component (A) in the epoxy resin composition is 20% by mass or more and 75% by mass or less, and the epoxy resin composition satisfies the following formula (1): Component (A): a bisphenol-type epoxy resin having a number average molecular weight of 250 or more and 365 or less Component (B): A latent curing agent having at least one active hydrogen selected from the group consisting of dicyandiamide or its derivatives, and imidazole compounds. Latent hardener Component (C): Acid anhydride and / or isocyanate compound 0.14≦Wc / Wb≦2.00 (1) Here, Wb: number of moles of active hydrogen in component (B) Wc: number of moles of component (C).

2. 2. The molding material according to claim 1, wherein the epoxy resin composition further comprises a bisphenol-type epoxy resin having a number average molecular weight of 366 or more and 1,000 or less as a component (D).

3. The molding material according to claim 1 or 2, wherein the epoxy resin composition further comprises a compound containing a carboxy group as component (E).

4. The molding material according to claim 3, wherein the epoxy resin composition satisfies the following formula (2): 1≦(Me / Mc)×100≦90…(2) Here, Mc: number of moles of component (C) Me: The number of moles of carboxy groups in component (E).

5. The molding material according to any one of claims 1 to 4, wherein the epoxy resin composition is heated at 150°C for 30 minutes, and a cured product obtained by heating the composition at 120°C for 5 hours has a volatilization amount of 1 μg / g or more and 100 μg / g or less.

6. The molding material according to any one of claims 1 to 5, wherein the amount of volatilization when the epoxy resin composition is heated at 40°C for 24 hours to thicken it, and the amount of volatilization when the epoxy resin composition is cured at 150°C for 30 minutes are both 0.01% by mass or more and 5.00% by mass or less.

7. The molding material according to any one of claims 1 to 6, wherein the epoxy resin composition further comprises a glycidyl amine-type epoxy resin as component (F) in an amount of 8% by mass or more and 20% by mass or less of all epoxy resin components in the epoxy resin composition.

8. The molding material according to any one of claims 1 to 7, wherein the epoxy resin composition has a viscosity at 25°C of 0.1 Pa·s or more and 3.0 Pa·s or less.

9. It has a sheet shape and a basis weight of 500 g / m ２ More than 2500g / m ２ The molding material according to any one of claims 1 to 8, wherein:

10. The molding material according to any one of claims 1 to 9, wherein the content of component (B) in the epoxy resin composition is 1% by mass or more and 15% by mass or less.

11. The molding material according to any one of claims 1 to 10, wherein component (B) is dicyandiamide and / or a derivative thereof.

12. The reinforcing fibers are discontinuous reinforcing fibers with a number average fiber length of 3 mm or more and 100 mm or less, and are substantially randomly oriented as bundle aggregates in the molding material. The bulkiness Bm of the bundle aggregate of discontinuous reinforcing fibers defined by the following formula (3) is 1.5 cm ３ / g or more 5cm ３ The molding material according to any one of claims 1 to 11, wherein the molecular weight is 1 / g or less. Bm=Tm / Fm...(3) Here, Tm: Thickness (cm) of the bundle of discontinuous reinforcing fibers Fm: Mass of reinforcing fibers per unit area in the molding material (g / cm ２ )

13. The molding material according to any one of claims 1 to 12, wherein the reinforcing fibers are carbon fibers.

14. A fiber-reinforced composite material obtained by curing the molding material according to any one of claims 1 to 13.

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