Epoxy resin composition, molded article, molding material for fiber-reinforced composite material and fiber-reinforced composite material

Abstract

To provide an epoxy resin composition which is excellent in quick curability and viscosity stability, and has high heat resistance of a resin cured product, and a fiber-reinforced composite material which is composed of the epoxy resin composition.SOLUTION: An epoxy resin composition contains the following components [A], [B] and [C], and satisfies all the conditions (i), (ii) and (iii). [A]: epoxy resin, [B]: sulfonamide compound represented by formula (I), [C]: catalyst, and (i) in 100 mass% of the epoxy resin composition, 40 mass% or more of the component [A] is contained. (ii) With respect to 100 pts.mass of the component [A], 1.0 pts.mass or more and 30.0 pts.mass or less of the component [B] is contained. (iii) With respect to 100 pts.mass of the component [A], 0.01 pts.mass or more and 5.0 pts.mass or less of the component [C] is contained. In the formula, R1 is a C1-10 straight chain / branched alkyl group, a cycloalkyl group or an aryl ring; and R2 is H or a C1-10 straight chain / branched alkyl group.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to an epoxy resin composition that is preferably used for aerospace parts and general industrial applications, and to a molded article, a molding material for fiber-reinforced composite material, and a fiber-reinforced composite material each using the same. [Background technology]

[0002] Epoxy resin compositions are widely used as matrix resins for fiber-reinforced composite materials, taking advantage of their excellent heat resistance, adhesiveness, and mechanical strength. Traditionally, intermediate substrates such as prepregs, in which the reinforcing fibers are pre-impregnated with matrix resin, have been widely used in the manufacture of fiber-reinforced composite materials, due to the ease of transportation and shaping. However, in recent years, due to the demand for high productivity, resin injection molding methods such as resin transfer molding (RTM) that do not use intermediate substrates are becoming more widely used.

[0003] In resin injection molding, matrix resin is injected and impregnated into reinforcing fibers placed in a mold using vacuum or pressure. At this time, the matrix resin needs to have a stable viscosity so that it can maintain a low viscosity until the injection and impregnation is complete. In addition, to improve productivity, the resin needs to be fast curing so that it can cure quickly at a specified temperature after injection and impregnation.

[0004] Patent Document 1 describes an epoxy resin composition that has excellent fast curing properties and uses an epoxy resin, an imidazole curing agent, and a sulfonamide compound as an imidazole curing accelerator.

[0005] Patent Document 2 describes an epoxy resin composition that uses a liquid aromatic amine compound as a curing agent, and thus has excellent viscosity stability and also excellent tensile strength utilization rate of fiber-reinforced composite materials. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2005-344112 A [Patent Document 2] JP 2021-116404 A Summary of the Invention [Problem to be solved by the invention]

[0007] The epoxy resin composition described in Patent Document 1 contains a large amount of an imidazole curing agent and thus has excellent rapid curing properties during thermal curing, but there is no mention of viscosity stability.

[0008] The epoxy resin composition described in Patent Document 2 exhibits excellent viscosity stability, but lacks rapid curing during thermal curing. In addition, since it contains a large amount of curing agent, the crosslinked structure of the cured product becomes non-uniform, and the heat resistance is insufficient.

[0009] The present invention aims to improve these drawbacks and provide an epoxy resin composition which has both viscosity stability and rapid curing properties during heat curing, while also providing excellent heat resistance of the heat-cured resin cured product; a molding material for a fiber-reinforced composite material which comprises said epoxy resin composition and reinforcing fibers; and a fiber-reinforced composite material obtained by heat curing said molding material for a fiber-reinforced composite material. [Means for solving the problem]

[0010] As a result of intensive research aimed at solving the above problems, the present inventors have found an epoxy resin composition having the following configuration, and have completed the present invention. [1] An epoxy resin composition comprising the following components [A], [B], and [C] and satisfying all of the conditions (i), (ii), and (iii). [A]: Epoxy resin [B]: a sulfonamide compound represented by formula (I) [C]:Catalyst (i) The epoxy resin composition contains 40% by mass or more of component [A] based on 100% by mass. (ii) Component [B] is contained in an amount of 1.0 part by mass or more and 30.0 parts by mass or less per 100 parts by mass of component [A]. (iii) The component [C] is contained in an amount of 0.01 parts by mass or more and 5.0 parts by mass or less per 100 parts by mass of the component [A].

[0011] [ka]

[0012] (In formula (I), R 1 R represents a substituted or unsubstituted linear or branched alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group, or an aryl ring. 2 represents a hydrogen atom or a substituted or unsubstituted linear or branched alkyl group having 1 to 10 carbon atoms. 1 , R 2 consists only of carbon atoms, hydrogen atoms, and halogen atoms.) [2] In formula (I), R 2 is a hydrogen atom. [3] The epoxy resin composition according to [1] or [2], wherein component [C] is at least one compound selected from the group consisting of heterocyclic amine compounds, quaternary onium salts, and inorganic salts. [4] The epoxy resin composition according to any one of [1] to [3], wherein the component [C] is an imidazole compound. [5] The epoxy resin composition according to [4], wherein component [C] is an imidazole compound having a triazine structure in the molecule. [6] Component [D]: The epoxy resin composition according to any one of [1] to [5], which contains an isocyanate compound as an additive. [7] The epoxy resin composition according to any one of [1] to [6], wherein there exists a value of X such that the glass transition temperature of the cured resin obtained by thermal curing at X°C for 60 minutes is 0.8×X°C or higher, where X is a real number of 25 or more and 250 or less. [8] A molded article obtained by heat-curing the epoxy resin composition according to any one of [1] to [7]. [9] A molding material for a fiber-reinforced composite material, comprising the epoxy resin composition according to any one of [1] to [7] and reinforcing fibers.

[10] A fiber-reinforced composite material comprising the molded article according to [8] and reinforcing fibers.

[11] A fiber-reinforced composite material obtained by heat curing the molding material for a fiber-reinforced composite material according to [9]. Effect of the Invention

[0013] According to the present invention, it is possible to provide an epoxy resin composition which has both viscosity stability and fast curing properties, and which also produces a thermoset resin product having excellent heat resistance. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] The epoxy resin composition of the present invention contains, as essential components, component [A]: an epoxy resin, component [B]: a sulfonamide compound represented by formula (I), and component [C]: a catalyst. First, these components will be described.

[0015] (Component [A]) The component [A] in the present invention is an epoxy resin. Such an epoxy resin is not particularly limited as long as it is a compound having an epoxy group in the molecule. For example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, amine type epoxy resin, etc. can be mentioned. The epoxy resin may be used alone or in combination of two or more kinds.

[0016] Commercially available bisphenol A type epoxy resins that can be used include jER (registered trademark) 825 and jER (registered trademark) 828 (both manufactured by Mitsubishi Chemical Corporation), Epototo (registered trademark) YD-128 and Epototo (registered trademark) YD-8125 (both manufactured by Nippon Steel Chemical & Material Co., Ltd.).

[0017] Commercially available bisphenol F type epoxy resins include, for example, "jER (registered trademark)" 806, "jER (registered trademark)" 4004P (both manufactured by Mitsubishi Chemical Corporation), and "EPICLON (registered trademark)" 830 (manufactured by DIC Corporation).

[0018] Examples of the amine-type epoxy resin used in the present invention include tetraglycidyldiaminodiphenylmethane, triglycidylaminophenol, and diglycidylaniline.

[0019] Commercially available products of tetraglycidyldiaminodiphenylmethane include "Sumiepoxy (registered trademark)" ELM434 (manufactured by Sumitomo Chemical Co., Ltd.) and "Araldite (registered trademark)" MY720 (manufactured by Huntsman Advanced Materials).

[0020] Commercially available triglycidylaminophenol products that can be used include "Sumiepoxy (registered trademark)" ELM100 (manufactured by Sumitomo Chemical Co., Ltd.), "Araldite (registered trademark)" MY0500, "Araldite (registered trademark)" MY0600 (all manufactured by Huntsman Advanced Materials), and "jER (registered trademark)" 630 (manufactured by Mitsubishi Chemical Corporation).

[0021] Commercially available diglycidylaniline products that can be used include GAN (N,N-diglycidylaniline) and GOT (N,N-diglycidyl-o-toluidine) (both manufactured by Nippon Kayaku Co., Ltd.).

[0022] The epoxy resin composition of the present invention contains 40% by mass or more of component [A] based on 100% by mass of the epoxy resin composition. If the content of component [A] is less than 40% by mass, the heat resistance of the cured resin obtained by thermally curing the epoxy resin composition of the present invention becomes insufficient as a matrix resin for fiber-reinforced composite materials. Component [A] is preferably contained in an amount of 50% by mass or more, more preferably 70% by mass or more, based on 100% by mass of the epoxy resin composition.

[0023] (Component [B]) The component [B] in the present invention is a sulfonamide compound represented by the following formula (I).

[0024] [ka]

[0025] (In formula (I), R 1 R represents a substituted or unsubstituted linear or branched alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group, or an aryl ring. 2 represents a hydrogen atom or a substituted or unsubstituted linear or branched alkyl group having 1 to 10 carbon atoms. 1 , R 2 consists only of carbon, hydrogen and halogen atoms).

[0026] In the epoxy resin composition of the present invention, component [B] acts as a curing agent. That is, by including component [B], the physical properties of the cured resin, including heat resistance, are improved.

[0027] In the component [B], in formula (I), R 2 Examples of commercially available compounds in which is other than a hydrogen atom include N-methylmethanesulfonamide, N-ethylmethanesulfonamide, N-methylbenzenesulfonamide, N-ethylbenzenesulfonamide, and N-ethyl-p-chlorobenzenesulfonamide (all manufactured by Tokyo Chemical Industry Co., Ltd.), and Topsizer (registered trademark) No. 3 (N-ethyl-o / p-toluenesulfonamide, manufactured by Fuji Amido Chemical Co., Ltd.).

[0028] In the component [B], in formula (I), R 2Commercially available compounds in which is a hydrogen atom include methanesulfonamide, benzenesulfonamide, p-chlorobenzenesulfonamide, phenylmethanesulfonamide, and cyclohexylsulfonamide (all manufactured by Tokyo Chemical Industry Co., Ltd.), Topsizer (registered trademark) No. 1S (p-toluenesulfonamide), Topsizer (registered trademark) No. 5 (o / p-toluenesulfonamide), and orthoamide (o-toluenesulfonamide) (all manufactured by Fuji Amide Chemical Co., Ltd.).

[0029] Here, component [B] is R 2 is preferably a hydrogen atom. 2 When is a hydrogen atom, the heat resistance of the obtained cured resin product tends to be excellent.

[0030] The epoxy resin composition of the present invention contains 1.0 to 30.0 parts by mass of component [B] relative to 100 parts by mass of component [A]. If the content of component [B] is less than 1.0 part by mass, the fast curing property of the epoxy resin composition becomes insufficient. If the content of component [B] is more than 30.0 parts by mass, the heat resistance of the thermoset resin hardened product becomes insufficient. Component [B] is preferably contained in an amount of 1.0 to 25 parts by mass, more preferably 5.0 to 20 parts by mass, relative to 100 parts by mass of component [A]. By containing component [B] in this range, the balance between fast curing property and heat resistance is easily improved.

[0031] (Component [C]) The component [C] in the present invention is a catalyst that accelerates the thermosetting reaction of the epoxy resin composition. There are no particular limitations on the component [C] as long as it accelerates the thermosetting reaction of the epoxy resin composition.

[0032] Examples of the catalyst preferably used in the present invention include heterocyclic amine compounds, imidazolium salts, quaternary onium salts, inorganic salts, etc. These catalysts may be used alone or in combination of two or more kinds.

[0033] Commercially available heterocyclic amine compounds include "Curezol (registered trademark)" 2E4MZ, "Curezol (registered trademark)" 2MZA-PW, "Cureduct (registered trademark)" P-0505 (all manufactured by Shikoku Kasei Co., Ltd.), 1,8-diazabicyclo[5.4.0]undec-7-ene, 1,5-diazabicyclo[4.3.0]-5-nonene, 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene, and 1,5,7-triazabicyclo[4.4.0]dec-5-ene (all manufactured by Tokyo Kasei Kogyo Co., Ltd.).

[0034] Commercially available imidazolium salts that can be used include 1-ethyl-3-methylimidazolium bromide, 1-ethyl-3-methylimidazolium bromide, 1-ethyl-3-methylimidazolium chloride, and 1-ethyl-3-methylimidazolium iodide (all manufactured by Tokyo Chemical Industry Co., Ltd.).

[0035] Commercially available quaternary onium salts that can be used include benzyltrimethylammonium bromide, tetrabutylammonium bromide, tetrabutylammonium iodide, and tetrapropylammonium bromide (all manufactured by Tokyo Chemical Industry Co., Ltd.), "TBP-BB (registered trademark)", "TPP-PB (registered trademark)", and "TPP-MB (registered trademark)" (all manufactured by Hokko Sangyo Co., Ltd.).

[0036] As commercially available inorganic salts, sodium chloride, lithium chloride, lithium bromide, lithium iodide, calcium iodide (all manufactured by Tokyo Chemical Industry Co., Ltd.), etc. can be used.

[0037] In particular, the component [C] in the present invention preferably contains at least one compound selected from the group consisting of heterocyclic amine compounds, quaternary onium salts, and inorganic salts. By using such a compound as the component [C], the epoxy resin composition is likely to have an excellent balance between the fast curing property and the heat resistance. More preferably, the component [C] contains at least one imidazole compound, and more preferably contains at least one imidazole having a triazine structure in the molecule. By using an imidazole compound as the component [C], the epoxy resin composition is likely to have a particularly favorable balance between the viscosity stability and fast curing property, and the heat resistance of the resin cured product, and by using an imidazole having a triazine structure, the viscosity stability is likely to be even more excellent.

[0038] The epoxy resin composition of the present invention contains 0.01 to 5.0 parts by mass of component [C] relative to 100 parts by mass of component [A]. If the content of component [C] is less than 0.01 parts by mass, the fast curing property of the epoxy resin composition becomes insufficient. If the content of component [C] is more than 5.0 parts by mass, the viscosity stability of the epoxy resin composition becomes insufficient. Component [C] is preferably contained in an amount of 0.01 to 4.0 parts by mass, more preferably 1.0 to 4.0 parts by mass, relative to 100 parts by mass of component [A]. By containing component [C] in this range, the balance between storage stability and fast curing property of the epoxy resin composition tends to be better.

[0039] The epoxy resin composition of the present invention can achieve both the fast curing property and viscosity stability required for injection molding and also have excellent heat resistance only when the contents of components [B] and [C] satisfy the above-mentioned conditions. This property cannot be achieved when components [B] or [C] are contained alone, and is specifically expressed only when a sulfonamide compound is used as component [B].

[0040] The epoxy resin composition of the present invention may contain component [D]: an additive within a range that does not impair the effects of the invention. Examples of the additives that can be used include tougheners, heat resistance improvers, diluents, solvents, flame retardants, thixotropic agents, and defoamers. In particular, since high heat resistance is often required for fiber-reinforced composite materials, it is preferable that the epoxy resin composition of the present invention contains a heat resistance improver.

[0041] The heat resistance improver is not particularly limited as long as it can improve the heat resistance of the thermoset resin product. For example, an isocyanate compound can be used.

[0042] Examples of isocyanate compounds that can be suitably used in the epoxy resin composition of the present invention include diphenylmethane diisocyanate (MDI), tolylene diisocyanate (TDI), hexamethylene diisocyanate (HDI), phenyl isocyanate, p-toluenesulfonyl isocyanate (PTSI), etc. These isocyanate compounds may be used alone or in combination of two or more kinds.

[0043] The epoxy resin composition of the present invention preferably contains 80 mass% or less of an additive, more preferably 60 mass% or less, even more preferably 10 mass% or more and 60 mass% or less, and particularly preferably 30.0 mass% or more and 60 mass% or less, based on 100 mass% of the epoxy resin composition.

[0044] The epoxy resin composition of the present invention is heat-cured at a predetermined temperature X°C for 60 minutes to obtain a cured resin product with a glass transition temperature (Tg) of 0.8×X°C or more, preferably in the range of 25 to 250. It is more preferable that the value of X exists where the glass transition temperature is 0.85×X°C or more, and even more preferable that the value of X exists where the glass transition temperature is 0.9×X°C or more. In general, in the injection molding of fiber-reinforced composite materials, the mold is demolded while the temperature of the mold is maintained at the thermosetting temperature to shorten the molding cycle. Therefore, it is preferable that the matrix resin exhibits sufficient rigidity of the cured resin even at temperatures near the thermosetting temperature in addition to rapid curing at the thermosetting temperature. The rigidity of the molded product is positively correlated with the glass transition temperature of the cured resin product, and the glass transition temperature being increased to 80% of the thermosetting temperature means that a sufficient crosslinking structure is formed in the cured resin product, and the rigidity of the molded product is increased to a degree that allows demolding.

[0045] The epoxy resin composition of the present invention may be prepared using a machine such as a kneader, a planetary mixer, a three-roll mill, or a twin-screw extruder. If uniform mixing is possible, the ingredients may be mixed by hand using a beaker and a spatula.

[0046] The epoxy resin composition of the present invention can be used as a fiber-reinforced composite material in which it is integrated with reinforcing fibers. The epoxy resin composition prepared by the above method is heat-cured to form a molded product, and then integrated with reinforcing fibers, or the epoxy resin composition prepared by the above method is integrated with reinforcing fibers to form a molding material for fiber-reinforced composite materials, and then heat-cured to obtain a fiber-reinforced composite material in which the epoxy resin composition of the present invention is the matrix resin. The method of integration of the epoxy resin composition with reinforcing fibers is not particularly limited, and examples thereof include the RTM method, the liquid composite molding method, the filament winding method, the hand layup method, the pultrusion method, and the prepreg method.

[0047] The epoxy resin composition of the present invention can maintain a low viscosity from room temperature to the heat curing temperature, so that the impregnation characteristics of the reinforcing fiber can be optimized according to the molding process. In addition, since the composition can be cured quickly at the heat curing temperature, the composition is particularly suitable for the RTM method.

[0048] In the manufacturing method of a fiber-reinforced composite material by the injection molding method using the epoxy resin composition of the present invention, the temperature at the time of injection of the epoxy resin composition is not particularly limited, but it is preferable to place reinforcing fibers in a mold kept at 23° C. to 180° C. and inject the epoxy resin composition of the present invention. The heat curing temperature does not need to be the same as the temperature at the time of injection, and the time required for heat curing may be shortened by appropriately increasing the temperature.

[0049] In the present invention, the mold used in the RTM method may be a closed mold made of a rigid material, or an open mold made of a rigid material and a flexible film (bag). In the latter case, the reinforcing fiber substrate can be placed between the open mold made of a rigid material and the flexible film. As the rigid material, existing materials such as metals such as steel and aluminum, fiber reinforced plastics (FRP), wood, and gypsum are used. As the material for the flexible film, polyamide, polyimide, polyester, fluororesin, silicone resin, etc. are used.

[0050] The reinforcing fibers used in the fiber-reinforced composite material of the present invention are not particularly limited. Glass fibers, carbon fibers, aramid fibers, boron fibers, alumina fibers, silicon carbide fibers, etc. can be used, and two or more of these fibers may be mixed and used. From the viewpoint of obtaining a lightweight and highly rigid fiber-reinforced composite material, it is preferable to use carbon fibers or glass fibers.

[0051] Since the fiber-reinforced composite material of the present invention has excellent heat resistance and mechanical properties, it can be preferably used for many structural materials, such as aircraft components such as fuselages, main wings, tail units, moving surfaces, fairings, cowls, doors, seats, and interior materials, spacecraft components such as motor cases and main wings, artificial satellite components such as structures and antennas, automobile components such as outer panels, chassis, aerodynamic components, and seats, railway car components such as structures and seats, and ship components such as hulls and seats. EXAMPLES

[0052] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the descriptions of these examples.

[0053] The components used in this embodiment are as follows:

[0054] <Materials used> Component [A]: Epoxy resin [A]-1 “jER (registered trademark)” 825 (manufactured by Mitsubishi Chemical Corporation).

[0055] Component [B]: a sulfonamide compound represented by formula (I) [B]-1 "Topsizer (registered trademark)" No. 1S (p-toluenesulfonamide, manufactured by Fuji Amido Chemical Co., Ltd.) [B]-2 "Topsizer (registered trademark)" No. 3 (N-ethyl-o / p-toluenesulfonamide, manufactured by Fuji Amido Chemical Co., Ltd.) [B]-3 “Topsizer (registered trademark)” No. 5 (o / p-toluenesulfonamide, manufactured by Fuji Amido Chemical Co., Ltd.).

[0056] ·Component [C]: Catalyst [C]-1 "Curezol (registered trademark)" 2E4MZ (2-ethyl-4-methylimidazole, manufactured by Shikoku Kasei Co., Ltd.) [C]-2 "Curezol (registered trademark)" 2MZA-PW (2,4-diamino-6-(2'-methylimidazolyl)ethyl-1-3-5-triazine, manufactured by Shikoku Kasei Co., Ltd.) [C]-3 Lithium bromide (Tokyo Chemical Industry Co., Ltd.) [C]-4 Tetrabutylammonium bromide (Tokyo Chemical Industry Co., Ltd.).

[0057] Component [D]: Additives [D]-1 "Millionate (registered trademark)" NM (diphenylmethane diisocyanate, manufactured by Tosoh Corporation) [D]-2 PEG300 (polyethylene glycol, manufactured by Sanyo Chemical Industries, Ltd.).

[0058] Amine hardeners other than component [B] Isophoronediamine (Tokyo Chemical Industry Co., Ltd.).

[0059] <Method for preparing epoxy resin composition> In a stainless steel beaker, predetermined amounts of component [A]: epoxy resin, component [B]: sulfonamide compound represented by formula (I), component [C]: catalyst, and component [D]: additive were placed, heated as necessary to make them compatible, and appropriately kneaded until each component was compatible to obtain an epoxy resin composition. The resin composition is as shown in Table 1 or Table 2.

[0060] <Method for measuring viscosity of epoxy resin composition> The complex viscosity (η * A parallel plate was used as the measuring tool, and the η was measured 10 seconds after placing the epoxy resin composition on the parallel plate. * was determined as the viscosity of the epoxy resin composition.

[0061] <Calculation method for thickening ratio of epoxy resin composition> The viscosity of the epoxy resin composition prepared according to the above <Preparation method of epoxy resin composition> at 1 minute after preparation was measured according to the above <Method for measuring viscosity of epoxy resin composition>, and the initial viscosity η of the epoxy resin composition was determined. 0In addition, an epoxy resin composition prepared in the same manner was allowed to stand for 60 minutes in a thermohygrostat (IG400: manufactured by Yamato Scientific Co., Ltd.) set at 25°C and 50 RH%, and then the η 0 The viscosity was measured in the same manner as above, and the viscosity η after leaving it at 25°C for 60 minutes was 60 Obtained η 60 η 0 The thickening ratio of the epoxy resin composition was calculated by dividing the result by 1.

[0062] <How to measure curing time> Using a polymer curing measuring device (ATD-1000: manufactured by Alpha Technologies), the complex viscosity (η * ) was measured over time. After the start of the measurement, η * The time when the viscosity first reached 1,000,000 Pa·s was defined as the curing time.

[0063] <Method of producing cured resin> The resin composition prepared according to the above <Preparation method of resin composition> was poured into an aluminum mold adjusted to a thickness of 2 mm using a 2 mm Teflon (registered trademark) spacer. The mold was then heated at 120°C for 60 minutes to obtain a 2 mm thick cured resin plate.

[0064] <Method for evaluating the glass transition temperature (Tg) of cured resin> A test piece measuring 12.7 mm wide and 45 mm long was cut out from the cured resin plate prepared according to the above <Preparation method of cured resin>, and dynamic viscoelasticity measurement was performed using a dynamic viscoelasticity measuring device (ARES-G2: manufactured by TA Instruments) at a heating rate of 5°C / min, a frequency of 1 Hz, and a temperature range of 30 to 260°C. The glass transition temperature (Tg) was determined as the temperature at the intersection of a tangent drawn to the glassy state and a tangent drawn to the glass transition temperature region in the obtained graph of storage modulus vs. temperature.

[0065] Example 1 An epoxy resin composition was prepared according to the above <Method of preparing resin composition> using 100 parts by mass of “jER (registered trademark)” 825 as component [A], 7.0 parts by mass of “Topsizer (registered trademark)” No. 1S as component [B], and 1.0 part by mass of “Curesol (registered trademark)” 2E4MZ as component [C].

[0066] The thickening ratio of this epoxy resin composition was measured according to the above <Method for deriving the thickening ratio of an epoxy resin composition> and was a good 1.2 times.

[0067] Furthermore, the curing time of this epoxy resin composition, measured according to the above-mentioned <Method for measuring curing time>, was a good 39 minutes.

[0068] Furthermore, the glass transition temperature of the cured resin produced according to the above <Production method of cured resin> was measured by the above <Evaluation method of glass transition temperature (Tg) of cured resin> and was found to be a good value of 109°C.

[0069] (Examples 2 to 9) Epoxy resin compositions and cured resins were prepared in the same manner as in Example 1, except that the components used were changed as shown in Table 1.

[0070] The thickening ratio of the epoxy resin composition in each Example was 1.0 to 1.6 times, and the curing time was 1.9 to 23 minutes, which was good, and the balance between fast curing and viscosity stability was excellent. In addition, when Tg was evaluated, good results were obtained at all levels. Among them, in the Example using an isocyanate compound as component [D], Tg was particularly excellent.

[0071] Comparative Example 1 An epoxy resin composition and a cured resin were prepared using the resin composition shown in Table 2 in the same manner as in Example 1. The epoxy resin composition did not contain component [B]. The Tg of the resulting cured resin was measured and found to be low at 43°C. This is presumably because the absence of component [B] meant that a sufficient crosslinking structure could not be formed by thermal curing.

[0072] Comparative Example 2 An epoxy resin composition and a cured resin were prepared in the same manner as in Example 1 using the resin composition shown in Table 2. The epoxy resin composition did not contain component [C]. When the curing time and Tg of the obtained cured resin were measured, the epoxy resin composition could not be thermally cured, and the curing time and Tg could not be measured. This is presumably because the curing reaction itself did not proceed because the epoxy resin composition did not contain component [C].

[0073] Comparative Example 3 An epoxy resin composition and a cured resin were prepared using the resin composition shown in Table 2 in the same manner as in Example 1. The epoxy resin composition contains an aliphatic amine compound, which is generally used as a curing agent for thermosetting epoxy resins, instead of component [B]. The Tg of the obtained cured resin was good at 147°C, but the viscosity increase ratio of the epoxy resin composition was 3.0 times, indicating low viscosity stability.

[0074] Comparative Example 4 An epoxy resin composition and a cured resin were prepared using the resin composition shown in Table 2 in the same manner as in Example 1. The epoxy resin composition contained 40 parts by mass of component [B] per 100 parts by mass of component [A]. The resulting epoxy resin composition had a good viscosity increase ratio of 1.2 times, but the crosslinking structure in the cured resin was non-uniform due to the inclusion of a large amount of component [B], and the Tg was low at 74°C.

[0075] Comparative Example 5 An epoxy resin composition and a cured resin were prepared using the resin composition shown in Table 2 in the same manner as in Example 1. The epoxy resin composition contained 8.0 parts by mass of component [C] per 100 parts by mass of component [A]. The obtained cured resin had a good Tg of 103°C, but the thickening ratio of the epoxy resin composition was only 2.2 times, and the viscosity stability was low due to the large amount of component [C] contained.

[0076] [Table 1]

[0077] [Table 2] [Industrial Applicability]

[0078] The epoxy resin composition of the present invention can provide a resin cured product that has both viscosity stability and fast curing properties and is also excellent in heat resistance. Fiber-reinforced composite materials made of the epoxy resin composition are excellent in productivity and physical properties, and therefore can be suitably used for aerospace components and general industrial structural components.

Claims

1. An epoxy resin composition comprising the following components [A], [B], and [C], and satisfying all of the conditions (i), (ii), and (iii). [A]: Epoxy resin [B]: A sulfonamide compound represented by formula (I) [C]: Catalyst (i) The epoxy resin composition contains 40% by mass or more of component [A] based on 100% by mass. (ii) Component [B] is contained in an amount of 1.0 part by mass or more and 30.0 parts by mass or less per 100 parts by mass of component [A]. (iii) The component [C] is contained in an amount of 0.01 parts by mass or more and 5.0 parts by mass or less per 100 parts by mass of the component [A]. 【Chemistry 1】 (In formula (I), R １ R represents a substituted or unsubstituted linear or branched alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group, or an aryl ring. ２ represents a hydrogen atom or a substituted or unsubstituted linear or branched alkyl group having 1 to 10 carbon atoms. １ , R ２ is composed only of carbon atoms, hydrogen atoms, and halogen atoms.)

2. In formula (I), R ２ 2. The epoxy resin composition according to claim 1, wherein

3. 2. The epoxy resin composition according to claim 1, wherein the component [C] is at least one compound selected from the group consisting of heterocyclic amine compounds, quaternary onium salts, and inorganic salts.

4. 2. The epoxy resin composition according to claim 1, wherein the component [C] is an imidazole compound.

5. 5. The epoxy resin composition according to claim 4, wherein the component [C] is an imidazole compound having a triazine structure in the molecule.

6. Component [D]: The epoxy resin composition according to claim 1, which contains an isocyanate compound as an additive.

7. 2. The epoxy resin composition according to claim 1, wherein there exists a value of X such that the glass transition temperature of the cured resin obtained by thermal curing at X° C. for 60 minutes is 0.8×X° C. or higher, where X is a real number of 25 or more and 250 or less.

8. A molded article obtained by heat curing the epoxy resin composition according to any one of claims 1 to 7.

9. A molding material for a fiber-reinforced composite material, comprising the epoxy resin composition according to any one of claims 1 to 7 and reinforcing fibers.

10. A fiber-reinforced composite material comprising the molded article according to claim 8 and reinforcing fibers.

11. A fiber-reinforced composite material obtained by heat curing the molding material for a fiber-reinforced composite material according to claim 9.

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