Method for manufacturing an electrodeposited coating, prepreg and epoxy resin composition

Abstract

Provided is a method for manufacturing an electrodeposited coating product suitable for manufacturing an electrodeposited coating product composed of carbon fiber-reinforced plastic. The method for manufacturing an electrodeposited coating product of the present invention has a molding step of curing a prepreg composed of a thickener of an epoxy resin composition in which a bisphenol A type epoxy resin, [4-(glycidyloxy)phenyl] diglycidyl amine, and a curing agent component are compounded, and a carbon fiber-reinforced material, to obtain a carbon fiber-reinforced plastic molded product, and an electrodeposition coating step of performing electrodeposition coating on the carbon fiber-reinforced plastic molded product. The epoxy resin composition, when cured at 140°C, produces a cured resin having a glass transition temperature G'-Tg higher than 100°C and lower than 200°C, and a dynamic storage modulus G' at 200°C that is 8% or more of the value at 100°C.

Description

TECHNICAL FIELD

[0001] The present application relates to a method for manufacturing an electrodeposited coating, a prepreg, and an epoxy resin composition. BACKGROUND

[0002] Carbon fiber reinforced plastics (CFRP) are lightweight and excellent in mechanical properties, and are suitable for parts of automobiles, motorcycles, bicycles, ships, railway vehicles, manned aircraft, unmanned aircraft, and other transport equipment, and in recent years, the importance thereof has been increasing.

[0003] As one of the methods for manufacturing a structure composed of carbon fiber reinforced plastics, there is a method using a prepreg such as SMC (Sheet Molding Compound) (Patent Literature 1). The prepreg is a molding intermediate material in which a carbon fiber reinforcement is impregnated with a resin in advance.

[0004] An electrodeposited coating obtained by performing electrodeposition coating on carbon fiber reinforced plastics obtained by curing SMC is known (Patent Literature 2, Patent Literature 3).

[0005] PRIOR ART DOCUMENTS

[0006] PATENT LITERATURE

[0007] Patent Literature 1: International Publication No. 2018 / 190329

[0008] Patent Literature 2: Japanese Patent Application Publication No. 2009-13306

[0009] Patent Literature 3: International Publication No. 2016 / 104416 SUMMARY

[0010] PROBLEMS TO BE SOLVED BY THE INVENTION

[0011] In electrodeposition coating, the workpiece reaches the highest temperature in the drying process, in which the temperature of the workpiece reaches about 200°C at the highest.

[0012] Therefore, if carbon fiber reinforced plastics in which the decrease in rigidity at the time of heating to 200°C is suppressed can be realized, it is considered that the same can be suitably used as a material for an electrodeposited coating.

[0013] The present application was completed as a result of studies conducted by the present inventors and the like based on the above idea, and the main object thereof is to provide a method for manufacturing an electrodeposited coating suitable for the manufacture of an electrodeposited coating composed of carbon fiber reinforced plastics, to provide a prepreg that produces carbon fiber reinforced plastics that can be preferably used for the manufacture of an electrodeposited coating, and to provide an epoxy resin composition that is preferably used in the manufacture of the prepreg.

[0014] Method for solving the problem

[0015] According to one embodiment of the present application, there is provided a method for manufacturing an electrodeposited coating product, comprising: a molding step of curing a prepreg to obtain a carbon fiber reinforced plastic molded product, the prepreg being composed of an epoxy resin composition in which a bisphenol-type epoxy resin, [4-(glycidyloxy)phenyl] diglycidyl amine, and a curing agent component are compounded, and a carbon fiber reinforcement material; and an electrodeposition coating step of performing electrodeposition coating on the carbon fiber reinforced plastic molded product.

[0016] According to another embodiment of the present application, there is provided a prepreg composed of an epoxy resin composition in which a bisphenol-type epoxy resin, [4-(glycidyloxy)phenyl] diglycidyl amine, and a curing agent component are compounded, and a carbon fiber reinforcement material, the epoxy resin composition producing, when cured at 140°C, a cured resin having a glass transition temperature G'-Tg higher than 100°C and lower than 200°C, and a dynamic storage modulus G' at 200°C that is preferably 8% or more, more preferably 10% or more, and further preferably 12% or more of the value at 100°C.

[0017] According to still another embodiment of the present application, there is provided a prepreg composed of an epoxy resin composition in which a bisphenol-type epoxy resin, [4-(glycidyloxy)phenyl] diglycidyl amine, 4,4'-methylenebis(N,N-diglycidylaniline), and a curing agent component are compounded, and a carbon fiber reinforcement material.

[0018] According to still another embodiment of the present application, there is provided an epoxy resin composition in which a bisphenol-type epoxy resin, [4-(glycidyloxy)phenyl] diglycidyl amine, and a curing agent component are compounded, the epoxy resin composition producing, when cured at 140°C, a cured resin having a glass transition temperature G'-Tg higher than 100°C and lower than 200°C, and a dynamic storage modulus G' at 200°C that is preferably 8% or more, more preferably 10% or more, and further preferably 12% or more of the value at 100°C.

[0019] According to still another embodiment of the present application, there is provided an epoxy resin composition in which a bisphenol-type epoxy resin, [4-(glycidyloxy)phenyl] diglycidyl amine, 4,4'-methylenebis(N,N-diglycidylaniline), and a curing agent component are compounded.

[0020] Effects of the Invention

[0021] According to one embodiment, there is provided a method for manufacturing an electrodeposited coating product suitable for manufacturing an electrodeposited coating product composed of a carbon fiber reinforced plastic.

[0022] According to another embodiment, there is provided a prepreg which produces a carbon fiber reinforced plastic that can be preferably used for the production of an electrodeposited coating.

[0023] Further, according to another embodiment, there is provided an epoxy resin composition that can be preferably used for the production of the prepreg. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 is a flowchart of the electrodeposited coating production method of the embodiment.

[0025] Figure 2 is a graph showing the temperature dependence of the dynamic storage modulus G' of cured resins produced from three kinds of epoxy resin compositions, respectively.

[0026] Figure 3 is a schematic diagram showing a sheet molding compound production apparatus. DETAILED DESCRIPTION

[0027] 1. A production method of an electrodeposited coating

[0028] One embodiment of the present application relates to a production method of an electrodeposited coating having a curing step of curing a prepreg to obtain a carbon fiber reinforced plastic molded product, and an electrodeposition coating step of performing electrodeposition coating on the carbon fiber reinforced plastic molded product. Figure 1

[0029] In the case of manufacturing an electrodeposited coating for an automobile part, for example, manufacturing efficiency is particularly valued, and thus in the curing step, it is preferable to perform curing of the prepreg at a curing temperature of 180°C or lower, more preferably 160°C or lower, and further preferably 150°C or lower.

[0030] In the case of compression molding, the curing temperature is the temperature of the mold.

[0031] In the electrodeposition coating step, electrodeposition coating is performed on the carbon fiber reinforced plastic molded product obtained in the curing step using a general electrodeposition coating technique. The technique disclosed in the above-described Patent Document 3 is also included in the electrodeposition coating techniques that can be employed in the electrodeposition coating step.

[0032] In the case where the electrodeposition coating step includes an electrodeposition step, a water washing step, and a drying step as sub-steps, in the drying step, the coated object is exposed to a high temperature of about 200°C at the highest. Thus, in the production method of an electrodeposited coating of the embodiment, improvement in the rigidity of the carbon fiber reinforced plastic molded product at 200°C as the coated object is sought. In more detail, improvement in the prepreg as the material of this carbon fiber reinforced plastic molded product is sought in order to improve the rigidity thereof at 200°C.

[0033] 2. A prepreg​

[0034] The prepreg used in the electrodeposition coating product manufacturing method of the embodiments is manufactured by sequentially performing the following first step and second step, or from the first step to the third step.

[0035] (First step) An epoxy resin composition is prepared by mixing various components including an epoxy resin component and a curing agent component.

[0036] (Second step) A composite is formed by impregnating a fiber reinforced material with the epoxy resin composition prepared in the first step.

[0037] (Third step) The epoxy resin composition in the composite formed in the second step is thickened.

[0038] The viscosity at 25°C (hereinafter also referred to as "initial viscosity") of the epoxy resin composition prepared in the first step, which is measured after the epoxy resin composition is put in a sealed container and left to stand at 25°C for 30 minutes from the time of preparation, is preferably 30 Pa-s or less, more preferably 15 Pa-s or less, and further preferably 10 Pa-s or less, and can be 5 Pa-s or less.

[0039] The lower the initial viscosity of the epoxy resin composition prepared in the first step, the more efficiently the second step can be performed at room temperature of 17°C or higher and 28°C or lower, which is suitable for work, without warming the epoxy resin composition.

[0040] The initial viscosity of the epoxy resin composition is measured, for example, using a rheometer such as HAAKE (registered trademark) MARS (registered trademark) 40 manufactured by Thermo Fisher Scientific, Inc., under conditions of oscillatory mode, angular velocity of 10 rad / s, plate diameter of 25 mm, and gap (distance between plates) of 0.5 mm.

[0041] In the epoxy resin composition prepared in the first step, at least a bisphenol-type epoxy resin and [4-(glycidyloxy)phenyl] diglycidyl amine are compounded as the epoxy resin component. The epoxy resin component is a component composed of a compound having an epoxy group, and can be a prepolymer or a monomer.

[0042] The preferred bisphenol-type epoxy resin is a bisphenol A-type epoxy resin and a bisphenol F-type epoxy resin, and in particular, a bisphenol A-type epoxy resin. The bisphenol A-type epoxy resin and the bisphenol F-type epoxy resin can be used individually, or together with other bisphenol-type epoxy resins. The bisphenol A-type epoxy resin and the bisphenol F-type epoxy resin can also be used in combination.

[0043] The bisphenol A type epoxy resin is a prepolymer containing a compound of formula (a) below in which n = 0, i.e., bisphenol A diglycidyl ether (BADGE), as an essential component, and usually further containing a compound of formula (a) below in which n is 1 or more.

[0044] [Chemical 1]

[0045]

[0046] Among commercially available bisphenol A type epoxy resins which are liquid at room temperature, the average value of n in formula (a) is about 0.1 to 0.2.

[0047] [4-(glycidyloxy)phenyl] diglycidyl amine is an epoxy compound represented by formula (b) below.

[0048] [Chemical 2]

[0049]

[0050] For example, by using, together with a commercially available bisphenol type epoxy resin, jER630 (jER is a registered trademark) manufactured by Mitsubishi Chemical Corporation, which is a [4-(glycidyloxy)phenyl] diglycidyl amine product having a viscosity of 0.5 to 1 Pa-s at 25°C, and in which the components have been adjusted so as to be in a liquid state at 25°C, it is possible to easily prepare an epoxy resin composition having an initial viscosity within the above-mentioned preferable range.

[0051] As is well known to those skilled in the art, among commercially available bisphenol type epoxy resins, there are several kinds having a viscosity of 5 Pa-s or less at 25°C.

[0052] The combined amount of the bisphenol type epoxy resin and the [4-(glycidyloxy)phenyl] diglycidyl amine in the epoxy resin composition prepared in the first step is adjusted so that, when the epoxy resin composition is cured, a cured resin having a glass transition temperature G'-Tg higher than 100°C and lower than 200°C, and a dynamic storage modulus G' at 200°C which is preferably 8% or more, more preferably 10% or more, and further preferably 12% or more of the value at 100°C.

[0053] The dynamic storage modulus G' is, for example, a storage shear modulus measured using a dynamic viscoelasticity measuring device such as ARES-G2 manufactured by TA Instruments, Inc., under the following conditions: torsion mode, temperature increasing rate 5°C / min, frequency 1 Hz, strain 0.1%, and temperature 25 to 250°C. The glass transition temperature G'-Tg is the temperature at the intersection of the approximate straight line of the flat region of the curve obtained by plotting log G' against temperature, and the approximate straight line of the region in which log G' sharply decreases of the curve.

[0054] In the measurement of dynamic storage modulus G', a test piece of 50 mm in length and 12.5 mm in width cut out from a resin plate of 2 mm in thickness can be used. To produce the resin plate, first, the epoxy resin composition immediately after preparation is vacuum-deaerated and then injected into a gap of 2 mm in thickness formed between two 4 mm thick glass plates by using spacers. Next, the epoxy resin composition held with the two glass plates is put into a hot air circulating thermostat preheated to 70°C so that the temperature in the thermostat is raised at a rate of 10°C / min in such a manner that the surface temperature of the glass plates is raised from 70°C to 140°C. Next, the temperature in the thermostat is further raised for 30 minutes while maintaining the surface temperature at 140°C, thereby curing the epoxy resin composition. Finally, the glass plates are removed to obtain a resin plate of 2 mm in thickness.

[0055] One of the purposes of incorporating the bisphenol-type epoxy resin, especially the bisphenol A-type epoxy resin, in the epoxy resin composition prepared in the first step is to suppress the curing shrinkage.

[0056] The greater the curing shrinkage of the base resin is, the greater the tendency to cause defects such as cracking and warping when the prepreg is cured.

[0057] Therefore, the total amount of the bisphenol-type epoxy resin incorporated in the epoxy resin composition prepared in the first step is preferably 50% by weight or more of the entire epoxy resin component incorporated in the epoxy resin composition.

[0058] In the preferred example, 50% by weight or more of the entire epoxy resin component incorporated in the epoxy resin composition can be the bisphenol A-type epoxy resin.

[0059] The bisphenol-type epoxy resin is inexpensive compared to other epoxy resins, and therefore increasing the amount of incorporation thereof contributes to the cost reduction of the prepreg.

[0060] The purpose of incorporating the [4-(glycidyloxy)phenyl] diglycidyl amine in the epoxy resin composition prepared in the first step is to improve the rigidity when the cured resin obtained from the epoxy resin composition is heated to near 200°C.

[0061] According to the results discovered by the present inventors, in the cured product of the epoxy resin composition incorporating the bisphenol-type epoxy resin and the [4-(glycidyloxy)phenyl] diglycidyl amine, the ratio of the value of the dynamic storage modulus G' at 200°C to that at 100°C tends to be higher depending on the amount of incorporation of the [4-(glycidyloxy)phenyl] diglycidyl amine. Such a tendency is not observed in at least other 3 kinds of diglycidyl amines, specifically 4,4'-methylenebis(N,N-diglycidyl aniline), [3-(glycidyloxy)phenyl] diglycidyl amine, and N,N,N',N'-tetraglycidyl-m-phenylenediamine.

[0062] From the viewpoint of improving the degree of improvement in rigidity at 200°C of the cured resin obtained from the epoxy resin composition, the total blending amount of the bisphenol-type epoxy resin is preferably 80% by weight or less of the entire epoxy resin component blended in the epoxy resin composition, and more preferably 75% or less. From the same viewpoint, the blending amount of the [4-(glycidyloxy)phenyl] diglycidyl amine is preferably 20% by weight or more of the entire epoxy resin component blended in the epoxy resin composition, and more preferably 25% by weight or more, and further preferably 30% by weight or more, and can be 35% by weight or more, or 40% by weight or more.

[0063] Within the range where the effects of the invention are produced, an epoxy resin component other than the bisphenol-type epoxy resin and the [4-(glycidyloxy)phenyl] diglycidyl amine can be blended in the epoxy resin composition.

[0064] One of the preferable examples of such an epoxy resin component is 4,4'-methylenebis(N,N-diglycidylaniline). By replacing a part of the bisphenol-type epoxy resin with 4,4'-methylenebis(N,N-diglycidylaniline), the degree of improvement in rigidity at 200°C of the cured resin obtained from the epoxy resin composition can be improved.

[0065] Examples of the epoxy resin component other than the bisphenol-type epoxy resin and the [4-(glycidyloxy)phenyl] diglycidyl amine that can be blended in the epoxy resin composition include a naphthalene-type epoxy resin, a biphenyl-type epoxy resin, a novolac-type epoxy resin, an epoxy resin having an oxazolidone ring structure, an alicyclic epoxy resin, and an aliphatic epoxy resin, but are not limited to these.

[0066] A preferable curing agent component that can be blended in the epoxy resin composition prepared in the first step is a latent curing agent. A latent curing agent is a curing agent that triggers the curing of an epoxy resin with heat as a trigger, and is a solid having low solubility in an epoxy resin at ordinary temperature, and functions as a curing agent only when it is dissolved or melted in the epoxy resin by heating.

[0067] The use of a latent curing agent is advantageous in suppressing the rise in the initial viscosity of the epoxy resin composition, and in addition, in improving the storage stability of the completed prepreg.

[0068] Various imidazoles, dicyandiamides, and boron trifluoride-amine complexes are typical examples of latent curing agents.

[0069] Imidazoles are compounds having an imidazole ring, and in addition to substituted imidazoles in which the hydrogen atoms of imidazole are substituted with substituents, imidazolium salts, imidazole complexes, and the like are also included in imidazoles.

[0070] The preferred examples of the substituted imidazole which functions as a latent curing agent are not limited, and include substituted imidazoles having an aromatic ring (which can be a heteroaromatic ring) such as 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine, 2-phenyl-4-methylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 2-phenyl-4-benzyl-5-hydroxymethylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole, 2-p-tolyl-4-methyl-5-hydroxymethylimidazole, 2-p-tolyl-4,5-dihydroxymethylimidazole, 2-m-tolyl-4-methyl-5-hydroxymethylimidazole, 2-m-tolyl-4,5-dihydroxymethylimidazole, and 1-cyanoethyl-2-phenylimidazole.

[0071] Imidazolium salts such as 1-cyanoethyl-2-ethyl-4-methylimidazolium trimellitate, 1-cyanoethyl-2-undecylimidazolium trimellitate, and 1-cyanoethyl-2-phenylimidazolium trimellitate are also preferred examples of imidazole-based latent curing agents.

[0072] Isocyanuric acid adducts of various substituted imidazoles such as 2-phenylimidazole, 2-methylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole, and 2-phenyl-4-methyl-5-hydroxymethylimidazole, and in particular, isocyanuric acid adducts of substituted imidazoles having a triazine ring such as 2,4-diamino-6-(2'-methylimidazolyl-(1'))-ethyl-s-triazine, 1-(4,6-diamino-s-triazin-2-yl)ethyl-2-undecylimidazole, and 2,4-diamino-6-[2-(2-ethyl-4-methyl-1-imidazolyl)ethyl]-s-triazine are included in particularly preferred examples of imidazole-based latent curing agents.

[0073] Amine adducts are also one of the preferred examples of latent curing agents. Amine adducts are substances in which a substituted imidazole and a tertiary amine are polymerized by reacting with an epoxy resin or an isocyanate, and have relatively low solubility in an epoxy resin.

[0074] The latent curing agent can be used alone as any one of the latent curing agents, or two or more kinds of latent curing agents can be used in combination.

[0075] When dicyandiamide is used as the latent curing agent, it is preferable to use a urea derivative such as 4,4'-methylenebis(phenyl dimethylurea) and 2,4-bis(3,3-dimethylureido)toluene as a curing accelerator in combination.

[0076] The curing agent component which can be incorporated in the epoxy resin composition prepared in the first step is not limited to the latent curing agent.

[0077] In the epoxy resin composition prepared in the first step, a curing agent other than the latent curing agent, such as a carboxylic anhydride, an aromatic amine, and a phenol-aldehyde resin, can be compounded on the basis of the latent curing agent or instead of the latent curing agent.

[0078] Among the carboxylic anhydrides, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, and methyl-5-norbornene-2,3-dicarboxylic anhydride (methyl-3,6-endomethylene-l,2,3,6-tetrahydrophthalic anhydride) each have a viscosity of less than 0.5 Pa-s at 25°C, and thus can be compounded in the epoxy resin composition prepared in the first step for the purpose of reducing the initial viscosity.

[0079] It is known that a carboxylic anhydride reacts with an epoxy compound at a low temperature to form a bond by the catalytic action of a tertiary amine (which can be a glycidyl amine). When a small amount of the carboxylic anhydride is compounded in the epoxy resin composition, for example, an amount of less than 20 parts by weight relative to 100 parts by weight of the epoxy resin component, the carboxylic anhydride functions as a thickening agent.

[0080] The thickening caused by the carboxylic anhydride is produced by the formation of a bond between the carboxylic anhydride and the epoxy compound. Thus, the carboxylic anhydride in the epoxy resin composition is consumed while thickening.

[0081] An amine compound also functions as a thickening agent by being compounded in the epoxy resin composition in an amount of 0.1 to 0.5 equivalents of active hydrogen per epoxy group. Examples of the amine compound which can be preferably used as a thickening agent are not limited, and include isophorone diamine, bis(4-aminocyclohexyl)methane, and 1,3-bis(aminomethyl)cyclohexane.

[0082] The thickening caused by the amine compound is produced by the formation of a bond between the amine compound and the epoxy compound. Thus, the amine compound added to the epoxy resin composition as a thickening agent is consumed while thickening.

[0083] A polyisocyanate (which can be a diisocyanate such as bis(4-isocyanatophenyl)methane, toluene diisocyanate) is a preferable example of a thickening agent. When a polyol (which can be a diol such as ethylene glycol, polyethylene glycol, isosorbide, neopentyl glycol, cyclohexanediol, cyclohexanedimethanol, 1,4-butanediol, 1,5-pentanediol, 3-methyl-l,5-pentanediol, and 1,6-hexanediol) is used together with the polyisocyanate, there is a tendency to promote the thickening of the epoxy resin composition.

[0084] The thickening caused by the polyisocyanate is produced by the formation of a bond between the polyisocyanate and the epoxy compound or the polyol compounded together. Thus, the polyisocyanate in the epoxy resin composition is consumed while thickening.

[0085] In the epoxy resin composition prepared in the first step, in addition to the epoxy resin component and the curing agent component, an arbitrary component can be incorporated. As the arbitrary component, a thickening agent, an internal release agent, a low shrinkage agent, a colorant, a flame retardant, an antioxidant, a modifier composed of a rubber, an elastomer, or a thermoplastic resin, an electrically conductive filler, an inorganic filler can be exemplified, without limitation.

[0086] A preferred example of the flame retardant is a non-halogen-based flame retardant. As the non-halogen-based flame retardant, an inorganic phosphorus-based flame retardant such as red phosphorus, an organic phosphorus-based flame retardant such as a phosphate ester, an organic phosphate, a phosphonate, a phosphinate; a nitrogen-based flame retardant such as a triazine compound, a cyanuric acid compound, an isocyanuric acid compound; an organic silicon-based flame retardant; an inorganic-based flame retardant such as a metal hydroxide, a metal oxide; an organic metal salt-based flame retardant such as ferrocene, an acetylacetone metal complex, and the like can be exemplified, without limitation. Two or more kinds of flame retardants selected from among them can be used in combination, for example, an organic phosphorus-based flame retardant and a nitrogen-based flame retardant can be used in combination.

[0087] From the viewpoint of productivity, the epoxy resin composition is preferably not a varnish. In the case where the epoxy resin composition is a varnish, a step of removing the solvent from the epoxy resin composition is further required after impregnating the fiber reinforcing material in the second step.

[0088] In the second step, a composite composed of the fiber reinforcing material and the epoxy resin composition is formed by impregnating a previously prepared fiber reinforcing material with the epoxy resin composition prepared in the first step.

[0089] The fiber reinforcing material preferably contains carbon fibers, and can be, for example, a carbon fiber buildup, a carbon fiber fabric, a carbon fiber nonwoven fabric, a carbon fiber non-crimped fabric, or the like.

[0090] In the case where the prepreg to be produced is a sheet-molding compound, the fiber reinforcing material is, for example, a carbon fiber buildup obtained by dispersing chopped carbon fiber bundles having a predetermined length in the range of 5 mm to 10 cm, preferably 1 to 6 cm, on a carrier film. In typical examples, the predetermined length can be 0.5 inch (about 1.3 cm), 1 inch (about 2.5 cm), 1.5 inch (about 3.8 cm), or 2 inch (about 5.1 cm).

[0091] In one example, in the second step, in order to reliably perform the impregnation of the fiber reinforcing material in a short time, the epoxy resin composition prepared in the first step can be used after being warmed to reduce the viscosity. The warming is performed in such a manner that the temperature of the epoxy resin composition does not exceed 80°C, preferably does not exceed 70°C, more preferably does not exceed 50°C, further preferably does not exceed 40°C.

[0092] In the third step performed as needed, the epoxy resin composition in the complex formed in the second step is thickened. This step is preferably performed by keeping the complex at a predetermined thickening temperature.

[0093] The thickening temperature is usually selected between room temperature and about 80°C. The holding time can be set by simply placing the epoxy resin composition in a closed container and investigating the change in viscosity when left standing at the thickening temperature. The viscosity of the epoxy resin composition after thickening is at least 500 Pa-s, preferably 1000 Pa-s or more at 25°C, and is usually 100000 Pa-s or less, preferably 50000 Pa-s or less, more preferably 20000 Pa-s or less, and can also be 10000 Pa-s or less, 8000 Pa-s or less, 6000 Pa-s or less, etc.

[0094] A case where the prepreg to be manufactured is a sheet-molded compound is particularly described as follows.

[0095] In the manufacture of the sheet-molded compound, for example, the sheet-molded compound manufacturing apparatus shown in Figure 3 can be used.

[0096] With reference to Figure 3 , a continuous fiber bundle 10 as a raw material of a fiber-reinforced material is drawn from a fiber package P and transported to a rotary knife 1.

[0097] The continuous fiber bundle 10 is a carbon fiber bundle composed of, for example, 1000 to 100000, preferably 3000 to 50000 carbon fiber filaments per bundle, and can be partially divided.

[0098] The continuous fiber bundle 10 is cut by the rotary knife 1 to become a chopped fiber bundle 20.

[0099] The fiber length of the chopped fiber bundle 20 is, for example, in the range of 5 mm to 100 mm, and can be 1 cm or more and less than 2 cm, 2 cm or more and less than 3 cm, 3 cm or more and less than 4 cm, 4 cm or more and less than 6 cm, etc.

[0100] The chopped fiber bundle 20 falls onto the surface of a first carrier film 51 traveling below the rotary knife 1 to form a fiber accumulation body 30.

[0101] Before the fiber accumulation body 30 is accumulated, a first resin paste layer 41L composed of a first resin paste 41 is applied to the surface of the first carrier film 51 using a first coater 2a provided with a doctor blade. The first resin paste 41 is the epoxy resin composition prepared in the first step.

[0102] The first carrier film 51 is a synthetic resin film resistant to the components of the first resin paste 41.

[0103] The material of the first carrier film 51 can be appropriately selected from polyolefins such as polyethylene and polypropylene, polyvinylidene chloride, vinyl chloride resin, polyamide, and the like.

[0104] The first carrier film 51 can be a multilayer film.

[0105] When the viscosity of the first resin paste 41 is 0.1 Pa s or more, further 0.5 Pa s or more, and 30 Pa s or less, further 15 Pa s or less at 25°C, the first resin paste layer 41L can be formed on the first carrier film 51 at a uniform thickness in a room where the air temperature is 17°C or more and 28°C or less without warming the first resin paste 41.

[0106] The unit area weight of the fiber accumulation 30, the thickness of the first resin paste layer 41L, and the thickness of the second resin paste layer 42L described later are set in consideration of the fiber content and the unit area weight of the sheet molding compound to be produced.

[0107] The fiber content of the sheet molding compound in which the fiber reinforced material is composed of carbon fibers can be, for example, 40 wt% or more and less than 45 wt%, 45 wt% or more and less than 55 wt%, 55 wt% or more and less than 65 wt, 65 wt% or more and less than 80 wt%, or the like.

[0108] The unit area weight of the sheet molding compound can be, for example, 500 g / m 2 1000 g / m 2 1000 g / m 2 1500 g / m 2 1500 g / m 2 2500 g / m 2 2500 g / m 2 3500 g / m 2 3500 g / m 2 5000 g / m 2 or the like.

[0109] The sheet molding compound generally has a larger unit area weight than the UD prepreg, and the thickness is also, for example, as large as 1 to 4 mm.

[0110] After the formation of the fiber accumulation 30, the first carrier film 51 is attached to the second carrier film 52 with the fiber accumulation 30 interposed therebetween, thereby forming a laminate 60.

[0111] Before the attachment, the second resin paste layer 42L composed of the second resin paste 42 is applied to one surface of the second carrier film 52 with the second coater 2b provided with a doctor blade. The second resin paste 42 is the epoxy resin composition prepared in the first step.

[0112] The laminate 60 is formed with the face of the first carrier film 51 on which the first resin paste layer 41L is applied facing the face of the second carrier film 52 on which the second resin paste layer 42L is applied.

[0113] The second carrier film 52 is a synthetic resin film that is resistant to components of the second resin paste 42, and can be the same material and structure as the first carrier film 51.

[0114] In order to impregnate the fiber accumulation body 30 with the first resin paste 41 and the second resin paste 42, the laminate 60 can be pressurized using the impregnator 3.

[0115] The laminate 60 that has passed through the impregnator 3 is wound on a reel.

[0116] Using Figure 3 The processes up to this point are performed using the sheet molding compound manufacturing device shown in the drawing.

[0117] The laminate 60 on the reel is held at a predetermined temperature for a certain period of time, and the epoxy resin composition that has impregnated the fiber accumulation body 30 is thickened, thereby completing the sheet molding compound.

[0118] The viscosity of the thickened epoxy resin composition at 25°C can be 1000 Pa-s or more and less than 2000 Pa-s, 2000 Pa-s or more and less than 3000 Pa-s, 3000 Pa-s or more and less than 4000 Pa-s, 4000 Pa-s or more and less than 5000 Pa-s, 5000 Pa-s or more and less than 6000 Pa-s, 6000 Pa-s or more and less than 8000 Pa-s, 8000 Pa-s or more and less than 10000 Pa-s, 10000 Pa-s or more and less than 15000 Pa-s, 15000 Pa-s or more and less than 20000 Pa-s, 20000 Pa-s or more and less than 50000 Pa-s, 50000 Pa-s or more and less than 100000 Pa-s, or the like.

[0119] The prepreg manufactured by the manufacturing method described above can not only be preferably used in the above-described electrodeposition coating product manufacturing method of the embodiment. In a carbon fiber reinforced plastic product including a product that has not been subjected to electrodeposition coating, by being manufactured using this prepreg in the material, it is possible to improve rigidity when exposed to a temperature higher than the glass transition temperature G'-Tg.

[0120] 3. Epoxy resin composition

[0121] One embodiment of the present application relates to an epoxy resin composition.

[0122] The epoxy resin composition prepared in the first step in the production method of the prepreg described in 2 above is included in the embodiments of the present application.

[0123] 4. Experimental results

[0124] Nine epoxy resin compositions were prepared using the materials shown in Table 1 below, and the cured resins were obtained by curing the epoxy resin compositions, and dynamic viscoelasticity measurement of the cured resins was performed.

[0125] [Table 1]

[0126] Label Article name Supplier Compound / material name jER 827 jER (Registered Trademark) 827 Mitsubishi Chemical Bisphenol A type epoxy resin jER 828 jER (Registered Trademark) 828 Mitsubishi Chemical Bisphenol A type epoxy resin jER 630 jER (Registered Trademark) 630 Mitsubishi Chemical [4-(glycidyloxy)phenyl] diglycidyl amine jER 604 jER (Registered Trademark) 604 Mitsubishi Chemical 4,4'-methylenebis(N,N-diglycidyl aniline) MY0600 Araldite (Registered Trademark) MY0600 Huntsman [3-(glycidyloxy)phenyl] diglycidyl amine TETRAD-X TETRAD (Registered Trademark)-X Mitsubishi Gas Chemical N,N,N',N'-tetraglycidyl-m-phenylenediamine 2MZA-PW Curezol (Registered Trademark) 2MZA-PW Shikoku Chemicals 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine PN-23J Amicure (Registered Trademark) PN-23J Ajinomoto Fine Techno Latent curing agent for amine adduct type epoxy resin 2E4MZ Curezol (Registered Trademark) 2E4MZ Shikoku Chemicals 2-ethyl-4-methylimidazole HN-2200 HN-2200 Hitachi Chemical 3 or 4-methyl-1,2,3,6-tetrahydrophthalic anhydride

[0127] The compounding ratios of the nine epoxy resin compositions (Compositions 1 to 9) prepared are shown in Table 2 below.

[0128] [Table 2]

[0129]

[0130] In the preparation of Compositions 1 to 9 shown in Table 2, 2MZA-PW and PN-23J as latent curing agents were each dispersed in jER827 or jER828 to make a master batch, and then mixed with other ingredients. In Compositions 1 to 8, the weight ratio of the latent curing agent in the master batch to jER827 was set to 2:1 (latent curing agent: epoxy resin). In Composition 9, the weight ratio of the latent curing agent in the master batch to jER828 was set to 1:1.

[0131] In the preparation of Compositions 1 to 9, HN-2200 was added to the mixture after the mixture of the ingredients other than HN-2200 was prepared.

[0132] The initial viscosity and the thickened viscosity, the glass transition temperature G'-Tg and the dynamic storage modulus G' at 100°C and 200°C of the cured resins obtained by curing Compositions 1 to 9, respectively, which were obtained by dynamic viscoelasticity measurement, are shown together in Table 2.

[0133] The initial viscosity is the viscosity at 25°C measured after the epoxy resin composition was prepared immediately after being put in a sealed container, and left to stand for 30 minutes at 25°C.

[0134] The thickened viscosity is the viscosity at 25°C measured after the epoxy resin composition was prepared immediately after being put in a sealed container, and left to stand for 7 days at 25°C.

[0135] In the dynamic viscoelasticity measurement, a test piece of 50 mm in length and 12.5 mm in width was cut out from a resin plate of 2 mm in thickness. To produce the resin plate, first, the epoxy resin composition immediately after preparation was vacuum-deaerated and then injected into a gap of 2 mm in thickness formed between two 4 mm thick glass plates by using spacers. Next, the epoxy resin composition held with the two glass plates was put into a hot air circulating thermostat preheated to 70°C so that the temperature inside the thermostat was raised at a rate of 10°C / minute from 70°C to 140°C in a manner that the surface temperature of the glass plates was 140°C. Next, the temperature inside the thermostat was further kept at 140°C for 30 minutes, whereby the epoxy resin composition was cured to give a resin plate of 2 mm in thickness.

[0136] The dynamic viscoelasticity measurement was performed using an ARES-G2 manufactured by TA Instruments, Inc. in a torsion mode at a temperature raising rate of 5°C / minute, a frequency of 1 Hz, a strain of 0.1%, and a temperature of 25 to 250°C.

[0137] B / A shown in Table 2 is the ratio of the value B of the dynamic storage modulus G' at 200°C to the value A at 100°C. It can be said that the greater the ratio, the smaller the decrease in the rigidity rate at heating to near 200°C.

[0138] In the compositions 1 to 9, bisphenol A type epoxy resins (jER827 or jER828) and glycidyl amines (jER630, jER604, MY0600, TETRAD-X) were respectively compounded as the epoxy resin component. Among them, the cured resins obtained from the compositions 2 and 3 in which jER630 ([4-(glycidyloxy)phenyl] diglycidyl amine) was compounded as the glycidyl amine had a significantly greater B / A than the cured resins obtained from the compositions 4 and 5 in which the same weight ratio of the glycidyl amine to the bisphenol A type epoxy resin was compounded but jER630 was not compounded.

[0139] Among the cured resins obtained from the compositions 1 to 3, there was a tendency that the greater the amount of jER630 compounded, the greater the B / A.

[0140] Among the cured resins obtained from the compositions 4 to 7, the B / A was equivalent regardless of the kind and the amount of the glycidyl amine used.

[0141] A graph showing the temperature dependence of the dynamic storage modulus G' of the cured resins produced from the composition 2, the composition 4, and the composition 5, respectively, is shown in Figure 2 .

[0142] 5. Summary of the Embodiments

[0143] Embodiments of the present application include, but are not limited to, the following.

[0144] [Embodiment 1] A method for producing an electrodeposited coating article, comprising: a molding step of curing a prepreg composed of an epoxy resin composition in which a bisphenol-type epoxy resin, [4-(glycidyloxy)phenyl]diglycidyl amine, and a curing agent component are compounded, and a carbon fiber-reinforced material, to obtain a carbon fiber-reinforced plastic molded article; and an electrodeposition coating step of performing electrodeposition coating on the carbon fiber-reinforced plastic molded article.

[0145] [Embodiment 2] The method for producing according to Embodiment 1, in the molding step, the prepreg is preferably cured at a temperature of 180°C or lower, more preferably 160°C or lower, further preferably 150°C or lower.

[0146] [Embodiment 3] The method for producing according to Embodiment 1 or 2, the epoxy resin composition, when cured at 140°C, produces a cured resin having a glass transition temperature G'-Tg higher than 100°C and lower than 200°C, and a dynamic storage modulus G' at 200°C that is preferably 8% or more, more preferably 10% or more, further preferably 12% or more of the value at 100°C.

[0147] [Embodiment 4] The method for producing according to any one of Embodiments 1 to 3, the total amount of the bisphenol-type epoxy resins compounded in the epoxy resin composition is preferably 50% by mass or more of the entirety of the epoxy resin components compounded in the epoxy resin composition.

[0148] [Embodiment 5] The method for producing according to any one of Embodiments 1 to 4, the bisphenol-type epoxy resin comprises a bisphenol A-type epoxy resin.

[0149] [Embodiment 6] The method for producing according to Embodiment 5, the total amount of the bisphenol A-type epoxy resins compounded in the epoxy resin composition is preferably 50% by mass or more of the entirety of the epoxy resin components compounded in the epoxy resin composition.

[0150] [Embodiment 7] The method for producing according to any one of Embodiments 1 to 6, the total amount of the bisphenol-type epoxy resins compounded in the epoxy resin composition is preferably 80% by mass or less, more preferably 75% or less, of the entirety of the epoxy resin components compounded in the epoxy resin composition.

[0151] [Embodiment 8] The method for producing according to any one of Embodiments 1 to 7, the amount of the [4-(glycidyloxy)phenyl]diglycidyl amine compounded in the epoxy resin composition is preferably 20% by mass or more, more preferably 25% by mass or more, further preferably 30% by mass or more, and can also be 35% by mass or more, 40% by mass or more, of the entirety of the epoxy resin components compounded in the epoxy resin composition.

[0152] [Embodiment 9] The production method according to any one of Embodiments 1 to 8, wherein 4,4'-methylenebis(N,N-diglycidylaniline) is further compounded in the epoxy resin composition.

[0153] [Embodiment 10] The production method according to any one of Embodiments 1 to 9, wherein the curing agent component comprises a latent curing agent.

[0154] [Embodiment 11] The production method according to Embodiment 10, wherein the latent curing agent comprises one or more curing agents selected from the group consisting of dicyandiamide, imidazoles, and amine adducts.

[0155] [Embodiment 12] The production method according to any one of Embodiments 1 to 11, wherein a thickening agent component is compounded in the epoxy resin composition.

[0156] [Embodiment 13] The production method according to any one of Embodiments 1 to 12, wherein a carboxylic anhydride having a viscosity of less than 0.5 Pa-s at 25°C is compounded in the epoxy resin composition.

[0157] [Embodiment 14] The production method according to any one of Embodiments 1 to 13, wherein the prepreg is a sheet molding compound.

[0158] [Embodiment 15] An electrodeposited coating product produced using the production method according to any one of Embodiments 1 to 14.

[0159] [Embodiment 16] A prepreg composed of an epoxy resin composition and a carbon fiber reinforcing material, the epoxy resin composition being compounded with a bisphenol-type epoxy resin, [4-(glycidyloxy)phenyl]diglycidylamine, and a curing agent component, the epoxy resin composition, when cured at 140°C, producing a cured resin having a glass transition temperature G'-Tg higher than 100°C and lower than 200°C, and a dynamic storage modulus G' at 200°C that is preferably 8% or more, more preferably 10% or more, and further preferably 12% or more of the value at 100°C.

[0160] [Embodiment 17] The prepreg according to Embodiment 16, wherein 4,4'-methylenebis(N,N-diglycidylaniline) is further compounded in the epoxy resin composition.

[0161] [Embodiment 18] A prepreg composed of an epoxy resin composition and a carbon fiber reinforcing material, the epoxy resin composition being compounded with a bisphenol-type epoxy resin, [4-(glycidyloxy)phenyl]diglycidylamine, 4,4'-methylenebis(N,N-diglycidylaniline), and a curing agent component.

[0162] [Embodiment 19] The prepreg according to any one of Embodiments 16 to 18, wherein the total amount of the bisphenol-type epoxy resins compounded in the epoxy resin composition is preferably 50% by mass or more of the entire epoxy resin components compounded in the epoxy resin composition.

[0163] [Embodiment 20] The prepreg according to any one of Embodiments 16 to 19, wherein the bisphenol-type epoxy resins include a bisphenol A-type epoxy resin.

[0164] [Embodiment 21] The prepreg according to Embodiment 20, wherein the total amount of the bisphenol A-type epoxy resins compounded in the epoxy resin composition is preferably 50% by mass or more of the entire epoxy resin components compounded in the epoxy resin composition.

[0165] [Embodiment 22] The prepreg according to any one of Embodiments 16 to 21, wherein the total amount of the bisphenol-type epoxy resins compounded in the epoxy resin composition is preferably 80% by mass or less, more preferably 75% by mass or less, of the entire epoxy resin components compounded in the epoxy resin composition.

[0166] [Embodiment 23] The prepreg according to any one of Embodiments 16 to 22, wherein the amount of the [4-(glycidyloxy)phenyl]diglycidyl amine compounded in the epoxy resin composition is preferably 20% by mass or more, more preferably 25% by mass or more, further preferably 30% by mass or more, and can also be 35% by mass or more, 40% by mass or more, of the entire epoxy resin components compounded in the epoxy resin composition.

[0167] [Embodiment 24] The prepreg according to any one of Embodiments 16 to 23, wherein the curing agent component includes a latent curing agent.

[0168] [Embodiment 25] The prepreg according to Embodiment 24, wherein the latent curing agent includes one or more curing agents selected from the group consisting of dicyandiamide, imidazoles, and amine adducts.

[0169] [Embodiment 26] The prepreg according to any one of Embodiments 16 to 25, wherein a thickening agent component is compounded in the epoxy resin composition.

[0170] [Embodiment 27] The prepreg according to any one of Embodiments 16 to 26, wherein a carboxylic anhydride having a viscosity of less than 0.5 Pa-s at 25°C is compounded in the epoxy resin composition.

[0171] [Embodiment 28] The prepreg according to any one of Embodiments 16 to 27, which is a sheet-molding compound.

[0172] [Embodiment 29] A method for producing a carbon fiber-reinforced plastic molded article, which comprises curing the prepreg described in any one of Embodiments 16 to 28.

[0173] [Embodiment 30] A carbon fiber-reinforced plastic molded article formed from a cured product of the prepreg described in any one of Embodiments 16 to 29.

[0174] [Embodiment 31] A method for producing an electrodeposited coating article, which comprises subjecting the carbon fiber-reinforced plastic molded article described in Embodiment 30 to electrodeposition coating.

[0175] [Embodiment 32] An epoxy resin composition, which is compounded with a bisphenol-type epoxy resin, [4-(glycidyloxy)phenyl]diglycidylamine, and a curing agent component, so that a cured resin having a glass transition temperature G'-Tg higher than 100°C and lower than 200°C and a dynamic storage modulus G' at 200°C that is preferably 8% or more, more preferably 10% or more, and further preferably 12% or more of the value at 100°C is produced when cured at 140°C.

[0176] [Embodiment 33] The epoxy resin composition described in Embodiment 32, which is further compounded with 4,4'-methylenebis(N,N-diglycidylaniline).

[0177] [Embodiment 34] An epoxy resin composition, which is compounded with a bisphenol-type epoxy resin, [4-(glycidyloxy)phenyl]diglycidylamine, 4,4'-methylenebis(N,N-diglycidylaniline), and a curing agent component.

[0178] [Embodiment 35] The epoxy resin composition described in any one of Embodiments 32 to 34, which has a viscosity at 25°C that is preferably 30 Pa-s or less, more preferably 15 Pa-s or less, and further preferably 10 Pa-s or less, and can also be 5 Pa-s or less.

[0179] [Embodiment 36] The epoxy resin composition described in Embodiment 35, which is not a varnish.

[0180] [Embodiment 37] The epoxy resin composition described in any one of Embodiments 32 to 36, which has a total amount of the compounded bisphenol-type epoxy resin that is preferably 50% by mass or more of the entire compounded epoxy resin component.

[0181] [Embodiment 38] The epoxy resin composition described in any one of Embodiments 32 to 37, which comprises a bisphenol A-type epoxy resin as the bisphenol-type epoxy resin.

[0182] [Embodiment 39] In the epoxy resin composition according to Embodiment 38, the total amount of the bisphenol A type epoxy resin is preferably 50% by weight or more of the total amount of the epoxy resin component.

[0183] [Embodiment 40] In the epoxy resin composition according to any one of Embodiments 32 to 39, the total amount of the bisphenol type epoxy resin is preferably 80% or less by weight of the total epoxy resin component, more preferably 75% or less.

[0184] [Embodiment 41] In the epoxy resin composition according to any one of Embodiments 32 to 40, the amount of [4-(glycidoxy)phenyl]diglycidylamine is preferably 20% by weight or more of the total amount of the epoxy resin component, more preferably 25% by weight or more, even more preferably 30% by weight or more, and may also be 35% by weight or more or 40% by weight or more.

[0185] [Embodiment 42] The epoxy resin composition according to any one of Embodiments 32 to 41, wherein the curing agent component comprises a latent curing agent.

[0186] [Embodiment 43] According to the epoxy resin composition of Embodiment 42, the latent curing agent comprises one or more curing agents selected from dicyandiamide, imidazoles and amine adducts.

[0187] [Embodiment 44] The epoxy resin composition according to any one of Embodiments 32 to 43 contains a thickener component.

[0188] [Embodiment 45] The epoxy resin composition according to any one of Embodiments 32 to 44 is formulated with a carboxylic anhydride having a viscosity of less than 0.5 Pa·s at 25°C.

[0189] [Embodiment 46] A method for manufacturing a prepreg includes impregnating a carbon fiber reinforcing material with the epoxy resin composition described in any one of Embodiments 32 to 45.

[0190] [Embodiment 47] The manufacturing method according to Embodiment 46 includes thickening the epoxy resin composition after impregnation.

[0191] [Embodiment 48] In the manufacturing method according to Embodiment 47, the prepreg is a sheet molding compound.

[0192] The present invention has been described above with reference to specific embodiments, but these embodiments are provided as examples and do not limit the scope of the invention. The embodiments described in this specification can be modified in various ways to achieve the inventive effect, and can be combined with features described in other embodiments within a feasible scope.

[0193] Industrial applicability

[0194] The electrodeposition coating product manufacturing method according to the embodiments can be used for manufacturing various electrodeposition coating products included in automobiles, motorcycles, bicycles, ships, railway vehicles, manned aircrafts, unmanned aerial vehicles and other transportation equipment, sports goods, leisure goods, home electric appliances, agricultural machines, building materials, and the like.

[0195] The prepreg according to the embodiments can be used for manufacturing various carbon fiber reinforced plastic parts included in automobiles, motorcycles, bicycles, ships, railway vehicles, manned aircrafts, unmanned aerial vehicles and other transportation equipment, sports goods, leisure goods, home electric appliances, agricultural machines, building materials, and the like.

[0196] Explanation of symbols

[0197] 1 rotary knife

[0198] 2a first coater

[0199] 2b second coater

[0200] 3 impregnator

[0201] 10 continuous fiber bundle

[0202] 20 chopped fiber bundle

[0203] 30 fiber accumulation body

[0204] 41 first resin paste

[0205] 41L first resin paste layer

[0206] 42 second resin paste

[0207] 42L second resin paste layer

[0208] 51 first carrier film

[0209] 52 second carrier film

[0210] 60 laminate

Claims

1. A sheet molding compound composed of an epoxy resin composition and a carbon fiber reinforcing material, the epoxy resin composition being compounded with a bisphenol-type epoxy resin, [4-(glycidyloxy)phenyl] diglycidyl amine, and a curing agent component, the epoxy resin composition, when cured at 140°C, producing a cured resin having a glass transition temperature G'-Tg higher than 100°C and lower than 200°C, and a dynamic storage modulus G' at 200°C of a value of 8% or more of a value at 100°C, the [4-(glycidyloxy)phenyl] diglycidyl amine being compounded in an amount of 25% by weight or more of the entirety of the epoxy resin components compounded in the epoxy resin composition, the epoxy resin composition being compounded with a carboxylic anhydride having a viscosity of less than 0.5 Pa-s at 25°C.

2. The sheet molding compound according to claim 1, the epoxy resin composition being further compounded with 4,4'-methylenebis(N,N-diglycidylaniline).

3. A sheet molding compound composed of an epoxy resin composition and a carbon fiber reinforcing material, the epoxy resin composition being compounded with a bisphenol-type epoxy resin, [4-(glycidyloxy)phenyl] diglycidyl amine, 4,4'-methylenebis(N,N-diglycidylaniline), and a curing agent component, the [4-(glycidyloxy)phenyl] diglycidyl amine being compounded in an amount of 25% by weight or more of the entirety of the epoxy resin components compounded in the epoxy resin composition, the epoxy resin composition being compounded with a carboxylic anhydride having a viscosity of less than 0.5 Pa-s at 25°C.

4. The sheet molding compound according to any one of claims 1 to 3, the total amount of the bisphenol-type epoxy resins compounded in the epoxy resin composition being 50% by weight or more of the entirety of the epoxy resin components compounded in the epoxy resin composition.

5. The sheet molding compound according to claim 1 or 3, the bisphenol-type epoxy resin comprising a bisphenol A-type epoxy resin.

6. The sheet molding compound according to claim 5, the total amount of the bisphenol A-type epoxy resins compounded in the epoxy resin composition being 50% by weight or more of the entirety of the epoxy resin components compounded in the epoxy resin composition.

7. The sheet molding compound according to claim 1 or 3, the total amount of the bisphenol-type epoxy resins compounded in the epoxy resin composition being 75% by weight or less of the entirety of the epoxy resin components compounded in the epoxy resin composition.

8. The sheet molding compound according to claim 1 or 3, the curing agent component comprising a latent curing agent.

9. The sheet molding compound according to claim 8, the latent curing agent comprising one or more curing agents selected from the group consisting of dicyandiamide, imidazoles, and amine adducts.

10. The sheet molding compound according to claim 1 or 3, the epoxy resin composition being compounded with a thickening agent component.

11. A method for producing a carbon fiber reinforced plastic molded article, comprising curing the sheet molding compound according to any one of claims 1 to 10.

12. A carbon fiber reinforced plastic molded article formed from the cured product of the sheet molding compound according to any one of claims 1 to 10.

13. A method for producing an electrodeposited coating article, wherein, The carbon fiber-reinforced plastic molded article according to claim 12 is subjected to electrodeposition coating.

14. A method for producing a sheet molding compound, comprising impregnating a carbon fiber-reinforced material with an epoxy resin composition to which a bisphenol-type epoxy resin, [4-(glycidyloxy)phenyl] diglycidyl amine, and a curing agent component are incorporated, such that when the epoxy resin composition is cured at 140°C, a cured resin having a glass transition temperature G'-Tg higher than 100°C and lower than 200°C and a dynamic storage modulus G' at 200°C that is more than 8% of the value at 100°C is produced, the [4-(glycidyloxy)phenyl] diglycidyl amine is incorporated in an amount of 25% by mass or more of the total of the epoxy resin component incorporated in the epoxy resin composition, the epoxy resin composition has incorporated therein a carboxylic anhydride having a viscosity of less than 0.5 Pa-s at 25°C.

15. The method for producing according to claim 14, wherein the epoxy resin composition further has incorporated therein 4,4'-methylenebis(N,N-diglycidylaniline).

16. A method for producing a sheet molding compound, comprising impregnating a carbon fiber-reinforced material with an epoxy resin composition to which a bisphenol-type epoxy resin, [4-(glycidyloxy)phenyl] diglycidyl amine, 4,4'-methylenebis(N,N-diglycidylaniline), and a curing agent component are incorporated, the [4-(glycidyloxy)phenyl] diglycidyl amine is incorporated in an amount of 25% by mass or more of the total of the epoxy resin component incorporated in the epoxy resin composition, the epoxy resin composition has incorporated therein a carboxylic anhydride having a viscosity of less than 0.5 Pa-s at 25°C.

17. The method for producing according to any one of claims 14 to 16, wherein the viscosity of the epoxy resin composition at 25°C is 30 Pa-s or less.

18. The method for producing according to claim 17, wherein the epoxy resin composition is not a varnish.

19. The method for producing according to claim 14 or 16, wherein the total amount of the bisphenol-type epoxy resins incorporated in the epoxy resin composition is 50% by mass or more of the total of the epoxy resin components incorporated in the epoxy resin composition.

20. The method for producing according to claim 14 or 16, wherein the bisphenol-type epoxy resins include a bisphenol A-type epoxy resin.

21. The method for producing according to claim 20, wherein the total amount of the bisphenol A-type epoxy resins incorporated in the epoxy resin composition is 50% by mass or more of the total of the epoxy resin components incorporated in the epoxy resin composition.

22. The method for producing according to claim 14 or 16, wherein the total amount of the bisphenol-type epoxy resins incorporated in the epoxy resin composition is 75% by mass or less of the total of the epoxy resin components incorporated in the epoxy resin composition.

23. The method for producing according to claim 14 or 16, wherein the curing agent component includes a latent curing agent.

24. The method for producing according to claim 23, wherein the latent curing agent includes one or more curing agents selected from the group consisting of dicyandiamide, imidazoles, and amine adducts.

25. The production method according to claim 14 or 16, wherein a thickening agent component is incorporated in the epoxy resin composition.

26. The production method according to claim 14 or 16, comprising thickening the epoxy resin composition after the impregnation.

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