Molding material for fiber-reinforced composite material, and fiber-reinforced composite material

Abstract

A molding material for a fiber-reinforced composite material according to the present invention is a molding material for a fiber-reinforced composite material, the present invention relates to an epoxy resin laminate obtained by impregnating a laminate, in which a constituent element [B]: a nonwoven fabric is incorporated between any of constituent elements [A]: a reinforcing fiber base material including a plurality of layers, with an epoxy resin composition including a constituent element [C]: an epoxy resin main agent and a constituent element [D]: an amine compound, the molding material for a fiber-reinforced composite material simultaneously satisfies condition 1: constituent element [B] is formed from an amorphous resin material, and condition 2: the time Cd20 (180 DEG C) at which the degree of curing of an epoxy resin composition containing constituent elements [C] and [D] is 20% at 180 DEG C is 15-45 minutes. Thus, a fiber-reinforced composite material having excellent impact resistance such as compressive strength and post-impact compressive strength in a humid and hot environment, and durability (suppressed generation of microcracks after thermal cycling) can be obtained.

Description

Technical Field

[0001] The present invention relates to a molding material for fiber-reinforced composite materials used in aviation, aerospace and general industrial applications, and a fiber-reinforced composite material produced using the molding material. Background Art

[0002] Fiber reinforced composites (FRP) have excellent lightweight potential and are therefore widely used in aircraft, sports cars, and the like. In particular, in order to be used as structural materials for load-bearing structures, prepregs, which are intermediate substrates obtained by impregnating matrix resins into reinforced fibers that are close together, have been widely used in the past. However, due to the demand for high productivity in recent years, the application of injection molding methods such as resin infusion (RI) methods such as RTM (Resin Transfer Molding) and VaRI (Vacuum assisted Resin Infusion) is being broadened. On the other hand, with regard to molded products based on the RI method, when used as structural materials, especially for aircraft, it is found that there are problems in terms of impact resistance, compression strength, and durability during long-term use, and there is a problem that the lightweight effect is limited compared to prepregs. In response to this, a design has been carried out to configure a thermoplastic resin material between the substrates to improve impact resistance. However, in this case, a reduction in mechanical properties, represented by compression characteristics during wet heat, and a reduction in durability caused by the generation of microcracks during hot and cold cycles can be observed.

[0003] Patent Documents 1, 2, and 3 disclose reinforcing fiber substrates in which a specific thermoplastic resin material is arranged in reinforcing fibers to thereby maintain excellent productivity while improving handleability and mechanical properties.

[0004] Patent Document 4 describes a method for increasing affinity with a matrix resin and improving impact resistance and durability against thermal cycling by disposing a crystalline thermoplastic resin in reinforcing fibers.

[0005] Patent Document 5 discloses a method for reducing weak portions in FRP and improving compression properties by not using stitching threads in bundling reinforcing fibers.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: International Publication No. 2022 / 149591

[0009] Patent Document 2: Japanese Patent Application Laid-Open No. 2020-23182

[0010] Patent Document 3: Japanese Patent Application Laid-Open No. 2003-80607

[0011] Patent Document 4: Japanese Patent Application Publication No. 2019-99987

[0012] Patent Document 5: International Publication No. 2010 / 046609 Summary of the Invention

[0013] Problems to be solved by the invention

[0014] The fiber-reinforced composite materials using reinforcing fiber substrates described in Patent Documents 1 and 2 have excellent compression properties under wet heat, but are insufficient in compression after impact (CAI) strength. Furthermore, there is no mention of resistance to thermal cycling.

[0015] The reinforcing fiber laminate described in Patent Document 3 has excellent impregnation properties and compression characteristics during resin injection molding, but has low CAI strength and resistance to thermal cycling.

[0016] The fiber-reinforced composite material formed of a crystalline resin material and reinforcing fibers described in Patent Document 4 has excellent CAI strength, but the crystalline resin material melts at the molding temperature, resulting in low wet hot compressive strength.

[0017] The fiber-reinforced composite material formed by using a carbon fiber-reinforced substrate described in Patent Document 5 is excellent in CAI strength, but is insufficient in compression properties under wet heat.

[0018] The present invention is an invention that solves the shortcomings of the above-mentioned prior art, and its purpose is to provide: a fiber-reinforced composite material that maintains excellent productivity and simultaneously satisfies mechanical properties that have been difficult to achieve at the same time, particularly excellent compression properties under wet and hot conditions, and impact resistance and durability under hot and cold cycles; and a molding material for the fiber-reinforced composite material that can provide the same.

[0019] Means for solving problems

[0020] The inventors of the present application have conducted intensive research to address the above-mentioned issues and, as a result, have discovered a fiber-reinforced composite material molding material having the following configuration, thereby completing the present invention. Specifically, the fiber-reinforced composite material molding material according to the present invention is a fiber-reinforced composite material molding material formed by impregnating a laminated body comprising component [B] incorporated between any of the layers of component [A] comprising a plurality of layers with an epoxy resin composition comprising component [C] and component [D], wherein the fiber-reinforced composite material molding material satisfies both the following conditions 1 and 2.

[0021] [A]: Reinforced fiber base, [B]: Non-woven fabric, [C]: Epoxy resin base, [D]: Amine compound

[0022] Condition 1: Component [B] is formed of an amorphous resin material

[0023] Condition 2: Time Cd for the epoxy resin composition containing components [C] and [D] to reach a degree of cure of 20% at 180°C 20 (180°C) 15 to 45 minutes

[0024] The fiber-reinforced composite material molding material according to the present invention preferably further satisfies at least one of the following conditions 3, 4, and 5.

[0025] Condition 3: (i) The ratio of the fiber diameter of component [B] in the resin-cured plate obtained by impregnating the aforementioned component [B] with the aforementioned epoxy resin composition and thermally curing at 190°C to the fiber diameter before thermal curing is set as Rexp(190°C), and (ii) The ratio of the fiber diameter of component [B] in the resin-cured plate obtained by impregnating the aforementioned component [B] with the aforementioned epoxy resin composition and thermally curing at 170°C to the fiber diameter before thermal curing is set as Rexp(170°C), and Rexp(190°C) and Rexp(170°C) are in the relationship expressed by the following formula (1).

[0026] 0.5<(Rexp(190℃)-Rexp(170℃))×5<5.0··· (1)

[0027] Condition 4: (i) the tensile modulus B82 (humidity controlled at 82°C) and the tensile modulus B25 (humidity controlled at 25°C) of component [B], and (ii) the tensile modulus E82 (wet heat 82°C) and the tensile modulus E25 (25°C, 50% RH) of the epoxy resin cured plate obtained by thermally curing the epoxy resin composition containing components [C] and [D] at 180°C are in the relationship shown in the following formula (2).

[0028] 0.7 <R ret =(B82 / B25) / (E82 / E25)<1.2··· (2)

[0029] Condition 5: When the laminate is compressed in the out-of-plane direction, the compressive stress at 160°C (σ160: MPa) and the compressive stress at 190°C (σ190: MPa) are in the relationship expressed by the following formula (3).

[0030] 0.5<(σ190 / σ160)<1.0··· (3)

[0031] Furthermore, the present invention also includes a fiber-reinforced composite material formed by thermally curing the above-mentioned molding material for the fiber-reinforced composite material.

[0032] Effects of the Invention

[0033] According to the present invention, a fiber-reinforced composite material having excellent compressive strength in a hot and humid environment, impact resistance such as CAI (compressive strength after impact), and durability (suppression of microcracks after thermal cycling) can be obtained. Furthermore, the molding material for a fiber-reinforced composite material of the present invention can be suitably used in the production of fiber-reinforced composite materials by injection molding. DETAILED DESCRIPTION

[0034] Hereinafter, the present invention will be described in detail together with embodiments.

[0035] The fiber-reinforced composite material molding material of the present invention comprises as essential components [A] a reinforcing fiber substrate, [B] a nonwoven fabric, [C] an epoxy resin main agent, and [D] an amine compound. First, components [A] and [B] will be described in detail.

[0036] (Component [A])

[0037] Component [A] of the present invention is a reinforcing fiber substrate. The reinforcing fibers used in the reinforcing fiber substrate are not particularly limited, and glass fibers, carbon fibers, aramid fibers, boron fibers, alumina fibers, silicon carbide fibers, and the like can be used. A mixture of two or more of these fibers can also be used. Carbon fibers are preferably used from the viewpoint of obtaining a lightweight and highly rigid fiber-reinforced composite material.

[0038] The form of the reinforcing fiber substrate of the present invention is not particularly limited as long as it is a sheet-like form (fiber aggregate) of multifilament yarns composed of the above-mentioned reinforcing fibers. Examples of the form of the reinforcing fiber substrate include woven fabrics (unidirectional, bidirectional, and multiaxial), knitted fabrics, braided fabrics, sheets formed by unidirectionally arranging (unidirectional sheets), and multiaxial sheets formed by stacking two or more unidirectional sheets. As the form of component [A], unidirectional sheets and multiaxial sheets are preferably used to improve the compressive strength of the fiber-reinforced composite material.

[0039] Here, the fiber-reinforced base material may be obtained by integrating a plurality of base materials by various joining means such as stitching threads, knotting threads, and adhesives.

[0040] The weight per layer of the reinforcing fiber substrate of the present invention (weight per unit area) is preferably 50 to 800 g / m 2 , more preferably 100 to 400 g / m 2 , particularly preferably 150 to 350 g / m 2 By setting the weight per unit area within the above range, the balance between workability during shaping of the fiber-reinforced substrate and impregnation properties of the epoxy resin composition is improved.

[0041] (Component [B])

[0042] Component [B] (nonwoven fabric) of the present invention must be composed of an amorphous resin material. Generally, the presence of a nonwoven fabric between layers of a reinforced fiber substrate (hereinafter referred to as "interlayers") can suppress the propagation of cracks in the interlayer resin layer, thereby improving the compression after impact (CAI) strength. By using an amorphous material in the nonwoven fabric and a specific epoxy resin composition in the matrix, a fiber-reinforced composite material can be obtained that exhibits excellent CAI strength, compressive strength under wet heat, and durability. Furthermore, deformation of the interlayer nonwoven fabric during the resin injection process can be suppressed, resulting in stable mechanical properties.

[0043] Here, in the present invention, amorphous means that the melting enthalpy measured by differential scanning calorimetry at a heating rate of 10° C. / min in accordance with JIS K7121 (1987) is less than 5 J / g.

[0044] As the amorphous resin material constituting the component [B], amorphous polyamide can be preferably used in order to achieve an excellent balance between heat resistance and durability.

[0045] As the amorphous polyamide, polyamide 4I, 6I, 9I, 12I, "GRILAMID" TR90, TR55, TR30, XE4003 (all manufactured by EMS-CHEMIE Japan Ltd.) and the like can be used.

[0046] The deflection temperature under load of the amorphous resin material used in component [B] of the present invention is preferably within the range of 100°C to 160°C. By being within this range, a fiber-reinforced composite material obtained using a nonwoven fabric (component [B]) formed from this amorphous resin material exhibits an excellent balance between compressive strength and impact resistance under wet heat.

[0047] The deflection temperature under load in the present invention can be measured, for example, by a three-point bending test method according to Method A described in JIS 7191-2 (2015).

[0048] Furthermore, for component [B] of the present invention, the retention ratio (B82 / B25) of the tensile modulus B82 at 82°C relative to the tensile modulus B25 at 25°C during humidity control is preferably within the range of 0.5 to 1.0. By being within this range, a fiber-reinforced composite material obtained using a nonwoven fabric (component [B]) made of this amorphous resin material will not develop weak portions, particularly under hot and humid conditions, and can exhibit excellent compressive strength.

[0049] Here, the tensile modulus of elasticity in the present invention can be measured by, for example, performing a tensile test on a resin plate obtained by processing the component [B] into a dumbbell shape in accordance with JIS K7161 (1994).

[0050] Here, the weight per unit area (g / m 2 ), that is, when the weight per unit area is Wb and the number average fiber diameter (μm) is Df, the value obtained by dividing Wb by Df (Wb / Df) is preferably in the range of 0.15 to 0.60. By being within this range, the impregnation time can be shortened without compromising the CAI strength of the fiber-reinforced composite material, thereby improving the surface quality of the fiber-reinforced composite material.

[0051] Here, the number average fiber diameter of component [B] can be obtained, for example, by taking a microscopic photograph of the surface or cross-section of the nonwoven fabric, measuring the fiber diameters of the fibers present in the image, and calculating the average value. The fiber diameter referred to above refers to the diameter of the fiber when its cross-sectional shape is a perfect circle. If the fiber is not a perfect circle, the longest diameter of the fiber when a cross-section perpendicular to the axial direction is taken is the fiber diameter.

[0052] Here, examples of the form of fibers constituting the nonwoven fabric of the present invention include long fibers and short fibers, and the nonwoven fabric can be produced by known methods such as meltblowing, spunbonding, air-laying, carding, and papermaking.

[0053] The fiber diameter of the fibers constituting the nonwoven fabric is not particularly limited, but is preferably 1 μm to 100 μm, more preferably 10 μm to 50 μm. Within this range, the fiber-reinforced composite material exhibits an excellent balance between wet-heat compressive strength and CAI strength.

[0054] The laminated body according to the present invention is a laminated body obtained by incorporating component [B] between any of the layers of component [A], which comprises multiple layers. It should be noted that the laminated body may also contain components other than component [A] and component [B], and the layers may be fixed together, for example, using sutures or tackifiers. This method of fixing is sometimes referred to as preforming.

[0055] Next, components [C] and [D] will be described.

[0056] (Component [C])

[0057] Component [C] in the present invention is an epoxy resin base. The epoxy resin base [C] is not particularly limited; examples thereof include bisphenol A epoxy resin, bisphenol F epoxy resin, biphenyl epoxy resin, naphthalene epoxy resin, Novolac epoxy resin, dicyclopentadiene epoxy resin, tetraglycidyldiaminodiphenylmethane, triglycidylaminophenol, and glycidylaniline. Epoxy resins may be used alone or in combination.

[0058] Examples of commercially available products of component [C] include “jER (registered trademark)” 154 and 828 (both manufactured by Mitsubishi Chemical Co., Ltd.), “Epiclon (registered trademark)” Epc830, N-740, HP7200L, and HP7200H (both manufactured by DIC Corporation), “SUMIEPOXY (registered trademark)” ELM434 and ELM434VL (both manufactured by Sumitomo Chemical Industries, Ltd.), “ARALDITE (registered trademark)” MY721, MY0510, and MY0600 (both manufactured by Huntsman Advanced Materials Co., Ltd.), GAN and GPT (both manufactured by Nippon Kayaku Co., Ltd.), and “TOREP (registered trademark)” A-204E (manufactured by Toray Fine Chemicals Co., Ltd.).

[0059] (Component [D])

[0060] The amine compound (component [D]) of the present invention is a compound capable of curing the epoxy resin base (component [C]), i.e., a curing agent. Examples thereof include dicyandiamide, aromatic amines, and aliphatic amines. Among them, aromatic amine compounds are preferably used because they provide excellent heat resistance and mechanical properties of the resulting fiber-reinforced composite material.

[0061] Aromatic amines are compounds formed by the direct addition of an amino group to an aromatic ring. Examples of aromatic amines include 4,4'-methylenebis(2-isopropyl-6-methylaniline) (M-MIPA), 4,4'-methylenebis(2,6-diethylaniline) (M-DEA), methylenebis(3-chloro-2,6-diethylaniline) (M-CDEA), 4,4'-methylenebis(2,6-bis(1-methylethyl)aniline) (M-DIPA), 4,4'-diamino-3,3'-dimethyldiphenylmethane (M-MEA), dimethylthiotoluenediamine (DMTDA), and diethyltoluenediamine (DETDA).

[0062] Examples of commercially available products of the aromatic amines include "Lonzacure (registered trademark)" M-MIPA, "Lonzacure (registered trademark)" M-DEA, "Lonzacure (registered trademark)" M-CDEA, and "Lonzacure (registered trademark)" M-DIPA (all manufactured by Lonza Corporation), "KAYAHARD (registered trademark)" AA (manufactured by Nippon Kayaku Co., Ltd.), "Ethacure (registered trademark)" 300 (manufactured by Albemarle Corporation), and "jER Cure (registered trademark)" WA (manufactured by Mitsubishi Chemical Co., Ltd.).

[0063] Regarding the components [C] and [D], the two are mixed and used as an epoxy resin composition. In addition, it is important that the time (Cd) until the degree of cure reaches 20% when the epoxy resin composition is kept at 180°C is 20 (180°C)) is in the range of 15 minutes to 45 minutes.

[0064] The fiber-reinforced composite material molding material of the present invention satisfies the following conditions simultaneously: component [B] is formed of an amorphous resin material (condition 1); and the time Cd for the epoxy resin composition containing components [C] and [D] to reach a degree of cure of 20% at 180°C is 20 The temperature (180°C) is set to 15 to 45 minutes (Condition 2). This allows for a balance between the CAI strength and the compressive strength under wet heat, which are usually mutually restrictive, of fiber-reinforced composite materials, while also providing crack resistance against thermal cycling.

[0065] The fiber-reinforced composite material molding material of the present invention is formed by impregnating a laminated body comprising component [B] incorporated between any of the layers of component [A], which comprises multiple layers, with an epoxy resin composition containing component [C] and component [D]. The nonwoven fabric of component [B] used in the present invention only needs to be in contact with component [A] and present on at least one surface of component [A].

[0066] Furthermore, in the present invention, it is preferred that, as condition 3, (i) the ratio of the fiber diameter of the component [B] in the resin cured plate obtained by impregnating the component [B] with the epoxy resin composition and thermally curing at 190°C to the fiber diameter before thermal curing is set as Rexp(190°C), and (ii) the ratio of the fiber diameter of the component [B] in the resin cured plate obtained by impregnating the component [B] with the epoxy resin composition and thermally curing at 170°C to the fiber diameter before thermal curing is set as Rexp(170°C), and Rexp(190°C) and Rexp(170°C) are in the relationship expressed by the following formula (1).

[0067] 0.5<(Rexp(190℃)-Rexp(170℃))×5<5.0··· (1)

[0068] Here, the larger the value of (Rexp(190°C) - Rexp(170°C)) in formula (1), the more the fibers of the non-woven fabric expand after thermal curing, and the smaller the value, the smaller the expansion rate. However, for the fiber-reinforced composite material of the present invention, it is preferred that the above value is within the range shown in formula (1) and satisfies the following conditions.

[0069] That is, the present invention satisfies the following conditions simultaneously: the component [B] is composed of a thermoplastic resin material (condition 1), the aforementioned Cd 20 (180°C) within the range of 15 minutes to 45 minutes (condition 2), and the above formula (1) (condition 3), thereby more reliably achieving a high level of compatibility between the CAI strength and the compressive strength in wet heat of the fiber-reinforced composite material, which are usually mutually constrained, and further improving the crack resistance to hot and cold cycles.

[0070] The fiber diameter of the component [B] present in the resin-cured plate obtained by thermally curing the composition comprising the component [B], the component [C] and the component [D] formed of an amorphous resin material can be obtained by taking a microscopic photograph from the surface of the resin-cured plate, measuring the fiber diameters of the fibers present in the image, and calculating the average value thereof.

[0071] Alternatively, in the present invention, it is preferred that, as condition 4, (i) the tensile modulus B82 (humidity controlled at 82°C) and the tensile modulus B25 (humidity controlled at 25°C) of component [B], and (ii) the tensile modulus E82 (wet heat 82°C) and the tensile modulus E25 (25°C, 50% RH) of the epoxy resin cured plate obtained by heat-curing the epoxy resin composition containing components [C] and [D] at 180°C are in the relationship represented by the following formula (2).

[0072] 0.7 <R ret =(B82 / B25) / (E82 / E25)<1.2··· (2)

[0073] For the fiber-reinforced composite material of the present invention, it is preferred that the above value is within the range shown in formula (2) and the following conditions are satisfied. That is, the present invention satisfies both the requirement that component [B] is composed of a thermoplastic resin material (condition 1), the aforementioned Cd 20By maintaining the temperature at 180°C for 15 to 45 minutes (Condition 2) and the above formula (2) (Condition 4), the fiber-reinforced composite material can more reliably achieve a high level of compatibility between the CAI strength and the compressive strength under wet heat, which are usually mutually exclusive, and exhibit crack resistance against thermal cycling. Furthermore, the fiber-reinforced composite material of the present invention can exhibit excellent performance in terms of wet heat shear properties, i.e., in-plane shear modulus and ILSS strength.

[0074] Alternatively, in the present invention, it is preferred that, as condition 5, when the aforementioned laminate is compressed in the out-of-plane direction, the compressive stress at 160°C (σ160: MPa) and the compressive stress at 190°C (σ190: MPa) are in the relationship of the following formula (3).

[0075] 0.5<(σ190 / σ160)<1.0··· (3)

[0076] Here, σ190 and σ160 in formula (3) represent the compressive stress when the laminate is compressed in the out-of-plane direction while being heated to 190°C and 160°C, respectively. Regarding the method for measuring σ190 and σ160, for example, a universal testing machine can be used to compress the laminate placed on a hot plate heated in a constant temperature bath, and the stress at the time when the volume fiber content (Vf_t) converted to the thickness of the laminate reaches 60% can be obtained. σ190 / σ160 represents the rate of change with respect to temperature when the laminate is compressed. The closer it is to the upper limit of 1.0, the smaller the change in compressive stress at Vf60% within the range of 160 to 190°C.

[0077] In the present invention, by making σ190 / σ160 within the range shown in formula (3), the degree of deformation of the laminate is reduced. Therefore, within the temperature range, the non-woven fabric arranged between the layers of the laminate during resin injection molding is not easily deformed, and the fiber-reinforced composite material obtained by resin injection molding has excellent mechanical properties and excellent impregnation during resin injection molding.

[0078] In addition, for the fiber-reinforced composite material of the present invention, it is preferred that the above value is within the range shown in formula (3) and the following conditions are satisfied. That is, the present invention satisfies the following conditions simultaneously: component [B] is composed of a thermoplastic resin material (condition 1), the above Cd 20 (180°C) is within the range of 15 minutes to 45 minutes (condition 2), and the above formula (3) (condition 5), thereby more reliably achieving a high level of compatibility between the CAI strength and the compressive strength in wet heat of the fiber-reinforced composite material, which are usually mutually constrained, and the crack resistance to hot and cold cycles is further improved.

[0079] It should be noted that Vf_t is defined by the following formula, and the symbols used here are as shown below.

[0080] Vf_t=(W×100) / (ρ×T)

[0081] W: 1cm 2 The mass of the reinforcing fibers contained in the laminate (g / cm 2 )

[0082] ρ: Density of reinforcing fiber (g / cm 3 )

[0083] T: Thickness of the laminate when compressed (cm)

[0084] Here, the epoxy resin composition containing components [C] and [D] may contain core-shell rubber particles as component [E]. The amount of core-shell rubber particles is preferably 1 to 10 parts by mass, and more preferably 3 to 6 parts by mass, relative to 100 parts by mass of the total epoxy resin base. Inclusion of component [E] within this range improves fracture toughness without compromising the elastic modulus of the epoxy resin cured product formed by thermally curing the epoxy resin composition, thereby improving interlaminar toughness of the fiber-reinforced composite material.

[0085] As the component [E], "Kane Ace (registered trademark)" MX-125, "Kane Ace (registered trademark)" MX-150, "Kane Ace (registered trademark)" MX-154, "Kane Ace (registered trademark)" MX-257, "Kane Ace (registered trademark)" MX-267, "Kane Ace (registered trademark)" MX-414, "Kane Ace (registered trademark)" MX-416, "Kane Ace (registered trademark)" MX-451 (all manufactured by Kaneka Co., Ltd.), "PARALOID (registered trademark)" EXL-2655, EXL-2668 (all manufactured by Dow Chemical Co., Ltd.), etc. can be used.

[0086] To prepare the epoxy resin composition containing the component [E], kneading can be performed using a machine such as a kneader, planetary mixer, three-roll mill, or twin-screw extruder, as long as uniform kneading can be achieved. Mixing can also be performed by hand using a beaker, spatula, or the like.

[0087] As described above, the fiber-reinforced composite material of the present invention can be obtained by the following method: impregnating a laminate obtained by incorporating component [B] between any of the layers of component [A] comprising a plurality of layers with an epoxy resin composition comprising component [C] and component [D] to obtain a fiber-reinforced composite material molding material, and then subjecting the fiber-reinforced composite material molding material to thermal curing. That is, at the stage of the fiber-reinforced composite material molding material, the epoxy resin is in an uncured state, and curing it to obtain a fiber-reinforced composite material. The laminate of the fiber-reinforced composite material molding material can also be pre-formed into a certain shape for use. The method of composite integration with the epoxy resin composition is not particularly limited, and for example, RI method, liquid compression molding method, hand lay-up molding method, etc. can be cited. Among them, the fiber-reinforced composite material molding material of the present invention can be suitably used in the RI method.

[0088] The RI method involves placing the laminated body in a mold, injecting a liquid epoxy resin composition into the mold to impregnate the reinforcing fibers and nonwoven fabric, and then heating the epoxy resin composition to cure it, thereby producing a fiber-reinforced composite material. The injection temperature and curing temperature of the epoxy resin composition can be the same or different and can be appropriately determined based on the size and shape of the molded article and the properties of the resin.

[0089] In the present invention, the mold used for the RI method can use a closed mold or an open mold and a flexible film (bag). In the latter case, the reinforcing fiber substrate is arranged between the open mold of rigid material and the flexible film, and the interior is usually decompressed to allow the resin to be impregnated.

[0090] In the present invention, the value (Ti / Df) obtained by dividing the interlayer thickness (Ti) of the fiber-reinforced composite material obtained by heat curing at 180°C for 2 hours by the fiber diameter (Df) of component [B] is preferably 0.7 to 1.5, more preferably 0.9 to 1.1. Within this range, the volume ratio between the CF (carbon fiber) layer and the nonwoven fabric layer is optimal, thereby further improving the compressive strength under wet heat.

[0091] In addition, in the present invention, the volume fiber content (Vf) of the fiber-reinforced composite material obtained by heat curing at 180°C for 2 hours is preferably 45-65%. By being within this range, the high mechanical properties required for the structural material can be exhibited, and the interlayer consisting of the CF layer and the non-woven fabric can be appropriately formed, thereby achieving excellent compressive strength under wet heat. Vf can be calculated, for example, by dividing the weight of the CF residue after decomposition by the weight of the test piece before decomposition according to the nitric acid decomposition method described in JIS K7075 (1991).

[0092] Example

[0093] The present invention will be described in more detail below with reference to Examples, but the present invention is not limited to the description of these Examples. The constituent elements used in the present Examples and Comparative Examples are as follows.

[0094] <Materials used>

[0095] Component [A]: Reinforcement fibers used in fiber-reinforced substrates

[0096] [A]-1 Carbon fiber "TORAYCA (registered trademark)" T800G-24K-71E (manufactured by Toray Corporation),

[0097] [A]-2 Carbon fiber “TORAYCA (registered trademark)” T1100G-24K-71E (manufactured by Toray Industries, Ltd.).

[0098] Component [B]: Thermoplastic resin material used in non-woven fabrics

[0099] [B]-1 Polyamide 6I,

[0100] [B]-2 Polyamide 6I / 610,

[0101] [B]-3 "GRILAMID (registered trademark)" TR90 (manufactured by EMS-CHEMIE Japan Ltd.),

[0102] [B]-4 "GRILAMID (registered trademark)" TR55 (manufactured by EMS-CHEMIE Japan Ltd.),

[0103] [B]-5 "GRILAMID (registered trademark)" TR30 (manufactured by EMS-CHEMIE Japan Ltd.),

[0104] [B]-6 polyamide 6 / 12 (20:80),

[0105] [B]-7 Polyamide 6 / 12 (80:20).

[0106] Component [C]: Epoxy resin base

[0107] [C]-1 "SUMIEPOXY (registered trademark)" ELM-434VL (manufactured by Sumitomo Chemical Co., Ltd.),

[0108] [C]-2GAN (manufactured by Nippon Kayaku Co., Ltd.),

[0109] [C]-3 "TOREP (registered trademark)" A-204E (manufactured by Toray Fine Chemicals Co., Ltd.),

[0110] [C]-4 "EPICLON (registered trademark)" HP-7200L (manufactured by DIC Corporation),

[0111] [C]-5 "EPICLON (registered trademark)" HP-7200H (manufactured by DIC Corporation),

[0112] [C]-6 "jER (registered trademark)" 825 (manufactured by Mitsubishi Chemical Co., Ltd.),

[0113] [C]-7 "EPICLON (registered trademark)" 830 (manufactured by DIC Corporation),

[0114] [C]-8 "jER (registered trademark)" 630 (manufactured by Mitsubishi Chemical Co., Ltd.).

[0115] Component [D]: Amine compound

[0116] [D]-1 "Ethacure" 300 (manufactured by Albemarle Corporation),

[0117] [D]-2 "jER Cure (registered trademark)" WA (manufactured by Mitsubishi Chemical Co., Ltd.),

[0118] [D]-3 "Lonzacure (registered trademark)" M-MIPA (manufactured by Lonza Corporation),

[0119] [D]-4 "KAYAHARD (registered trademark)" AA (manufactured by Nippon Kayaku Co., Ltd.),

[0120] [D]-5 "Lonzacure (registered trademark)" M-DEA (manufactured by Lonza Corporation),

[0121] [D]-6 "Lonzacure (registered trademark)" M-DIPA (manufactured by Lonza Corporation),

[0122] [D]-7 "Lonzacure (registered trademark)" M-CDEA (manufactured by Lonza Corporation),

[0123] [D]-8SEIKACURE-S (manufactured by SEIKA Corporation)

[0124] [D]-9 3,3'-DAS (manufactured by Mitsui Fine Chemicals, Inc.).

[0125] Component [E]: Core-shell rubber particles

[0126] "Kane Ace (registered trademark)" MX-414 (75% by mass of a glycidylamine-based epoxy resin and 25% by mass of butadiene-based core-shell rubber particles) (manufactured by Kaneka Corporation).

[0127] Other additives

[0128] DIC-TBC (tert-butylcatechol) (manufactured by DIC Corporation).

[0129] <Method for Preparing Epoxy Resin Composition>

[0130] Specified amounts of component [C] and component [E] were placed in a kneader, heated to 60-150°C, and mixed appropriately until the components were dissolved to obtain an epoxy base liquid. Component [D] and other additives were added to a separate container and heated as needed to dissolve them, to obtain a curing agent liquid. Specified amounts of the epoxy base liquid and curing agent liquid were mixed and degassed in a vacuum degassing machine for 60 minutes to obtain an epoxy resin composition. The composition of the epoxy resin is shown in Table 1.

[0131] <Cd of epoxy resin composition 20 Evaluation method (180°C)>

[0132] 2 mL of the epoxy resin composition obtained in the above-mentioned <Method for preparing epoxy resin composition> was weighed, and then placed on a micro press (MicroPress) and clamped, and the ionic viscosity was measured using a dielectric measuring device (curing monitor LT-451, manufactured by Lambent Technologies). The ionic viscosity of the epoxy resin composition takes the minimum value at the beginning of the measurement, increases as the curing proceeds, and saturates at the same time as the curing is completed. In the present invention, the curing index is calculated from the time-ionic viscosity curve obtained at 180°C in accordance with the test standard ASTME2039, and the time when the curing index reaches 20% under the condition of 180°C is calculated as Cd. 20 (180℃).

[0133] <Evaluation Method for Tensile Modulus E25 (25°C, 50% RH) of Epoxy Resin Composition>

[0134] After degassing the epoxy resin composition obtained according to the above <Preparation method of epoxy resin composition> in a vacuum, it was cured at a temperature of 180°C for 2 hours in a mold set to a thickness of 2mm using a 2mm thick "TEFLON (registered trademark)" gasket to obtain an epoxy resin cured plate with a thickness of 2mm. According to JIS K7161 (1994), the obtained epoxy resin cured plate was processed into a 1BA type dumbbell-shaped test piece. Using an INSTRON universal testing machine (manufactured by Instron), the distance between the chucks was set to 58mm, and a resin tensile test was carried out at a test speed of 1mm / min at room temperature (25°C, 50%RH) to measure the tensile modulus E25 (25°C, 50%RH). At this time, the average value of the values ​​obtained by measuring the number of samples n=8 was used as the value of the tensile modulus.

[0135] <Evaluation Method for Tensile Modulus E82 (Wet Heat 82°C) of Epoxy Resin Composition>

[0136] An epoxy resin cured plate was obtained using the same method as described in the "Evaluation Method for the Tensile Modulus E25 of the Epoxy Resin Composition (25°C, 50% RH)" section above. The resulting epoxy resin cured plate was processed into a 1BA dumbbell-shaped test piece in accordance with JIS K7161 (1994) and then immersed in boiling water for 48 hours. The removed test piece was subjected to a resin tensile test in a high-temperature environment (82°C) using an INSTRON universal testing machine (manufactured by Instron) with the chuck distance set to 58 mm and a testing speed of 1 mm / min. The tensile modulus E82 (wet heat 82°C) was measured. The tensile modulus was calculated as the average of the values ​​obtained from measurements performed on 8 samples (n = 8).

[0137] <Method for preparing thermoplastic resin material>

[0138] [B]-1, [B]-2, [B]-6, and [B]-7 described in the above "Materials Used" were prepared by a polycondensation method using pressurized autoclave conditions. For polyamide 6I ([B]-1), a reaction solution of isophthalic acid and hexamethylenediamine mixed at appropriate molar ratios was pressurized to 1.7 MPa in an autoclave using ion-exchanged water as a solvent, and reacted at 260°C for 3 hours to produce amorphous polyamide 6I. For polyamide 6I / 610 ([B]-2), a molar ratio of isophthalic acid / sebacic acid / hexamethylenediamine = 1 / 1 / 2 was blended to achieve a 50 / 50 copolymerization ratio of polyamide 6I and polyamide 610. The mixture was then reacted at 260°C for 5 hours under a pressure of 1.7 MPa in the presence of ion-exchanged water. The resulting amorphous polyamide 6I / 610 was obtained. Polyamide 6 / 12 (20:80) ([B]-6) was prepared by blending polyamide 6 and polyamide 12 at a molar ratio of ε-caprolactam / laurolactam = 1 / 4 so that the copolymerization ratio was 80 / 20. The mixture was reacted at 260°C for 5 hours at a pressure of 1.7 MPa in the presence of ion-exchanged water to obtain crystalline polyamide 6 / 12 (20:80). Polyamide 6 / 12 (80:20) ([B]-7) was prepared by blending polyamide 6 and polyamide 12 at a molar ratio of ε-caprolactam / laurolactam = 4 / 1 so that the copolymerization ratio was 80 / 20. The mixture was reacted at 260°C for 5 hours at a pressure of 1.7 MPa in the presence of ion-exchanged water to obtain crystalline polyamide 6 / 12 (80:20).

[0139] <Method for measuring melting enthalpy of thermoplastic resin material>

[0140] 5 mg of a thermoplastic resin material prepared or purchased according to the above-described "Method for Preparing Thermoplastic Resin Material" was weighed into a sample pan and measured using a differential scanning calorimeter (Q-2500, manufactured by TA Instruments Co., Ltd.) at a constant temperature increase of 10°C / min from 0°C to 250°C. The melting enthalpy was calculated based on the resulting DSC curve in accordance with JIS K7121 (1987).

[0141] <Method for Determination of Deflection Temperature Under Load of Thermoplastic Resin Materials>

[0142] Thermoplastic resin material prepared or purchased according to the "Method for Preparing Thermoplastic Resin Material" described above was placed on a stainless steel plate (with a 4mm thick stainless steel spacer). The stainless steel plate, preheated to 250°C, was stacked on top and held while being heated and pressed using a manual press. After cooling to room temperature, the resin material was removed and processed into test pieces with a length of 80mm, a width of 10mm, and a thickness of 4mm. These test pieces were subjected to a temperature creep test under a constant load of 1.8MPa according to Method A of JIS 7191-2 (2015), and the load deflection temperature was calculated.

[0143] <Evaluation Method for Tensile Modulus B25 (Humidity Control 25°C) of Thermoplastic Resin Materials>

[0144] The thermoplastic resin material prepared or purchased according to the above <Preparation method of thermoplastic resin material> is arranged on a stainless steel plate (which is provided with a stainless steel gasket with a thickness of 2 mm), and the stainless steel plate preheated to 250°C is overlapped from the top, and maintained while being heated and pressed using a manual press. After cooling to room temperature, the resin material is taken out and processed into a 1BA type dumbbell-shaped test piece in accordance with JIS K7161 (1994). The processed test piece is subjected to a 30-day humidity control treatment at room temperature (25°C, 50% RH). For the test piece subjected to the humidity control treatment, an INSTRON universal testing machine (manufactured by Instro n Co., Ltd.) is used, the distance between the chucks is set to 58 mm, and a resin tensile test is performed at a test speed of 1 mm / min at room temperature (25°C, 50% RH) to measure the tensile modulus B25 (humidification 25°C). At this time, the average value of the values ​​obtained by measuring the number of samples n=8 is used as the value of the tensile modulus.

[0145] <Evaluation Method for Tensile Modulus B82 (Humidity Control 82°C) of Thermoplastic Resin Materials>

[0146] 1BA dumbbell-shaped test pieces made of thermoplastic resin material were prepared using the same method as described in the "Evaluation Method for the Tensile Modulus B25 (Humidity Controlled at 25°C) of Thermoplastic Resin Material" section above. These pieces were then subjected to humidity conditioning at room temperature (25°C, 50% RH) for 30 days. The humidity-conditioned test pieces were subjected to a resin tensile test at a high temperature (82°C) using an INSTRON universal testing machine (manufactured by Instron) with the chuck distance set to 58 mm and a test speed of 1 mm / min. The tensile modulus B82 (humidity controlled at 82°C) was measured. The tensile modulus was calculated as the average value of the values ​​obtained from measurements performed on 8 samples (n = 8).

[0147] <Calculation Method of the Tensile Modulus Retention Ratio Rret of the Thermoplastic Resin Material and the Epoxy Resin Composition>

[0148] The retention rate R at 82°C of the thermoplastic resin material relative to the tensile elastic modulus at 25°C was calculated by dividing B82 obtained as described above by B25. retB Next, the retention rate R at 82°C of the epoxy resin composition relative to the tensile elastic modulus at 25°C was calculated by dividing E82 obtained as described above by E25. retE Next, R retB Divide by R retE , and the tensile modulus retention ratio R of the thermoplastic resin material and the epoxy resin composition is calculated. ret .

[0149] <Nonwoven Fabric Manufacturing Method>

[0150] Regarding the thermoplastic resin material used in the component [B] nonwoven fabric described in the above <Materials Used>, a meltblown nonwoven fabric manufacturing apparatus SWMB-T100 (manufactured by Shinwa Industry Co., Ltd.) was used to produce the nonwoven fabric at a cylinder temperature of 250 to 350°C.

[0151] <Method for measuring weight per unit area of ​​nonwoven fabric: Wb>

[0152] The weight per unit area (Wb) (g / m2) of the nonwoven fabrics produced according to the above-mentioned <Method for producing nonwoven fabrics> and purchased "Spunfab (registered trademark)" PA1206 and PA1209 (both manufactured by Spunfab Ltd.) were measured. 2 ). For a nonwoven fabric wound into a roll 500 mm wide, 400 mm × 400 mm samples were collected at 10 locations at intervals of 1 m. For each sample, the weight (Wb) obtained by measuring the weight using an electronic balance and dividing it by the area was averaged and the obtained value was used as the weight per unit area. The obtained Wb (g / m 2 ) as shown in Table 2 and following.

[0153] <Observation Method of Nonwoven Fabric Fiber Diameter>

[0154] The number average fiber diameter (Df) (μm) was measured for nonwoven fabrics produced according to the "Nonwoven Fabric Production Method" described above, as well as purchased "Spunfab (registered trademark)" PA1206 and PA1209 (both manufactured by Spunfab Ltd.). For each nonwoven fabric, ten 2 mm x 2 mm measurement samples were collected from arbitrary locations. Using a digital microscope VHX-6000 (manufactured by KEYENCE Co., Ltd.) (hereinafter referred to as VHX6000), the fiber diameters at 50 points were observed at 500x magnification and averaged to calculate Df. If the fiber's cross-sectional shape is a perfect circle, that diameter is used as the fiber diameter. If the fiber is not a perfect circle, the longest diameter of the fiber, measured when the cross-section is perpendicular to the axial direction, is used as the fiber diameter.

[0155] <Evaluation Method for Expansion Ratio of Nonwoven Fabric Fibers in Epoxy Resin Cured Sheets>

[0156] The epoxy resin composition obtained according to the above-mentioned <Method for Preparing an Epoxy Resin Composition> was degassed in a vacuum. The nonwoven fabric prepared according to the above-mentioned <Method for Preparing a Nonwoven Fabric> was then attached to a mold set to a thickness of 0.3 mm using a 0.3 mm thick "TEFLON (registered trademark)" spacer. The degassed epoxy resin composition was then injected and cured at 170°C and 190°C for 2 hours each to produce a 0.3 mm thick cured resin plate. A 5 mm x 5 mm measurement area was selected from the cured plates containing component [B], component [C], and component [D]. The fiber diameters were observed at 300x magnification using a VHX6000 and averaged at 50 points to obtain the fiber diameter. The fiber diameters when cured at 170°C (D170) and 190°C (D190) were calculated. D190 and D170 were divided by Df obtained according to the above-mentioned <Method of observing the fiber diameter of nonwoven fabric> to calculate Rexp(190° C.) and Rexp(170° C.).

[0157] <Method for producing a fiber-reinforced substrate>

[0158] Regarding the components [A]-1 and [A]-2 described in the above "Materials Used," a multiaxial loom was used to produce unidirectional sheets and satin woven fabric sheets, each consisting of multiple strands of [A]-1 or [A]-2 laid parallel to each other. The carbon fiber weights per unit area are as shown in Table 2 and subsequent tables.

[0159] <Method for producing laminate>

[0160] The reinforcing fiber substrate prepared according to the above-mentioned "Method for Preparing a Reinforcing Fiber Substrate" was cut into 400 mm x 400 mm, and the nonwoven fabric prepared according to the above-mentioned "Method for Preparing a Nonwoven Fabric" was placed on the upper surface. This product was used as the first layer. For the laminate used only for the compressive stress test, the reinforcing fiber substrate prepared according to the above-mentioned "Method for Preparing a Reinforcing Fiber Substrate" was cut into 50 mm x 50 mm, and the nonwoven fabric prepared according to the above-mentioned "Method for Preparing a Nonwoven Fabric" was placed on the upper surface. This product was used as the first layer. The fiber direction of the reinforcing fiber substrate in the first layer was set to 0°, and the laminate was produced to have the following laminated structure.

[0161] For compression after impact (CAI), open hole compression (OHC), compression stress test and thermal cycle durability test, the setting is [(+45° / -45° / 0° / 90°)] 2S , for interlaminar shear (ILSS) testing, it is set to [0°]8.

[0162] <Compression Stress Test Method>

[0163] A compression platen was placed on an INSTRON universal testing machine (manufactured by Instron). After heating the platen to 160°C or 190°C in a thermostatic chamber, a laminate for compressive stress testing, prepared according to the "Laminate Preparation Method" described above, was placed in the center of the platen. The laminate was compressed at a test speed of 1 mm / min to measure the compressive stress. The compressive stress generated when the laminate's Vf_t (%) reached 60% was measured with n = 20, and the average value was taken as σ160 (MPa) or σ190 (MPa). The obtained σ190 was divided by σ160 to calculate σ190 / σ160.

[0164] It should be noted that Vf_t is defined by the following formula, and the symbols used here are as shown below.

[0165] Vf_t=(W×100) / (ρ×T)

[0166] W: 1cm 2 The mass of the reinforcing fibers contained in the laminate (g / cm 2 )

[0167] ρ: Density of reinforcing fiber (g / cm 3 )

[0168] T: thickness of the laminate when compressed (cm).

[0169] <Fiber-reinforced composite molding method: VaRI method>

[0170] The laminate produced according to the above <Method for Producing Laminate> is placed on an aluminum tooling plate, and the whole is covered with a polyamide film bag. While the inside of the film is in a state of vacuum suction, it is heated in a hot air dryer set at 100°C. After confirming that the temperature of the laminate has reached 100°C, while maintaining the epoxy resin composition obtained according to the above <Method for Producing Epoxy Resin Composition> at 100°C, the resin composition is injected using the pressure difference from the atmospheric pressure. After impregnating with the epoxy resin composition, the temperature is raised to the molding temperature described after Table 2 while continuously reducing the pressure, and heat curing is carried out for 2 hours to obtain a molded product. This molding method is the Vacuum assisted resin infusion (VaRI) method.

[0171] <Molding Method of Fiber Reinforced Composite Material: RTM Method>

[0172] The laminate produced according to the above <Method for Producing Laminate> is placed on the lower mold of a carbon steel double-sided mold, and then the upper mold is closed and pressurized. The inside of the mold is heated to a specified temperature in a state of vacuum suction. Then, the epoxy resin composition obtained according to the above <Method for Producing Epoxy Resin Composition> is pressurized and injected from the injection hole, and heat curing is carried out for 2 hours to obtain a molded product. The molding temperature, the pressurizing pressure of the mold, and the injection pressure are shown after Table 2. This molding method is the Resin Trasfer Molding (RTM) method.

[0173] <CAI Test Method>

[0174] According to the above <Molding Method of Fiber Reinforced Composite Material: VaRI Method> or <Molding Method of Fiber Reinforced Composite Material: RI Method>, the laminate for CAI produced according to the above <Method for Producing Laminate> is heat cured to obtain a molded product. A rectangular test piece of 150 mm × 100 mm is cut out from the obtained molded product. At the center of the test piece, after applying a drop hammer impact of 8 J per 1 mm thickness of the test piece according to ASTM D7136, the residual compressive strength is measured according to the test standard ASTM D7137. The measurement is carried out under the condition of n = 6, and the average value is taken as the CAI strength (MPa).

[0175] <Room Temperature OHC Test Method>

[0176] The laminate for OHC prepared according to the above-mentioned "Laminate Preparation Method" was thermally cured according to the above-mentioned "Fiber-Reinforced Composite Material Molding Method: VaRI Method" or "Fiber-Reinforced Composite Material Molding Method: RI Method" to obtain a molded article. A 305 mm x 38 mm rectangular test piece was cut from the resulting molded article, and a 6.35 mm diameter hole was opened in the center of the test piece. Compression testing was conducted according to ASTM D6484 with n = 6, and the average value was used as the room temperature OHC strength (MPa).

[0177] <Wet heat OHC test method>

[0178] Similar to the "Room Temperature OHC Test Method" described above, a 305 mm x 38 mm rectangular test piece with a 6.35 mm hole opened in the center was prepared and immersed in hot water heated to 70°C for two weeks. The immersed test pieces were subjected to compression testing in accordance with the test standard AS™ D6484 at a high temperature of 82°C with n = 6 results. The average value was used as the wet heat OHC strength (MPa).

[0179] <Room Temperature In-Plane Shear Test Method>

[0180] The laminate for in-plane shear prepared according to the above-mentioned <Method for Forming Laminated Materials: VaRI Method> or <Method for Forming Fiber-Reinforced Composite Materials: RI Method> was thermally cured to produce a molded article. A 250 mm x 25 mm rectangular test piece was cut from the resulting molded article and subjected to in-plane shear testing according to ASTM D3518 at a test speed of 2 mm / min and n = 6. The average of the obtained in-plane shear modulus was used as the room temperature in-plane shear modulus (GPa).

[0181] <Wet heat in-plane shear test method>

[0182] A 250 mm x 25 mm rectangular test piece was prepared in the same manner as described in the "Room Temperature In-Plane Shear Test Method" and immersed in hot water heated to 70°C for two weeks. The immersed test piece was subjected to an in-plane shear test according to ASTM D3518 at a test speed of 2 mm / min and n = 6. The average of the obtained in-plane shear modulus was used as the wet-heat in-plane shear modulus (GPa).

[0183] <Room temperature ILSS test method>

[0184] The laminate for ILSS prepared according to the above-mentioned <Laminate Preparation Method> was thermally cured according to the <Fiber-Reinforced Composite Material Forming Method: VaRI Method> or <Fiber-Reinforced Composite Material Forming Method: RI Method> to obtain a molded article. Rectangular test pieces measuring 20 mm in the fiber direction and 10 mm in the direction perpendicular to the fibers were cut from the resulting molded article. Three-point bending tests were performed according to EN 2563, with n = 6 and a 10 mm distance between support points. The average value was used as the room temperature ILSS strength (MPa).

[0185] <Wet Heat ILSS Test Method>

[0186] A 20 mm x 10 mm rectangular test piece was prepared in the same manner as described in the "Room Temperature OHC Test Method" and immersed in hot water heated to 70°C for two weeks. The immersed test piece was subjected to a three-point bending test at 82°C (n=6) in accordance with the test standard EN2563. The average value was used as the wet-heat ILSS strength (MPa).

[0187] <Hot and cold cycle durability test method>

[0188] According to the above-mentioned <Molding method of fiber-reinforced composite materials: VaRI method> or <Molding method of fiber-reinforced composite materials: RI method>, the laminate for the hot and cold cycle durability test produced according to the above-mentioned <Method for producing laminates> is thermally cured to obtain a molded product. From the obtained molded product, a test piece with a size of 80mm×80mm is cut out and exposed to a hot and humid environment (50°C, 99% RH) for 12 hours. The exposed test piece is continuously subjected to 2000 times of hot and cold cycles from -55°C to 70°C. At this time, after reaching -55°C and 70°C, a temperature holding time of 15 minutes is set. After the hot and cold cycles are completed, a cross-section of the test piece is cut out and observed at a magnification of 200 times using VHX6000 to measure the number of cracks generated.

[0189] <Evaluation Method of Surface Quality and Interlayer Thickness>

[0190] The laminate for CAI, prepared according to the above-mentioned <Laminate Production Method>, was thermally cured according to the above-mentioned <Fiber-Reinforced Composite Material Molding Method: VaRI Method> or <Fiber-Reinforced Composite Material Molding Method: RTM Method> to produce a molded article. The surface obtained by cutting a cross section of the resulting molded article was polished, and the thickness between the CF layers was measured at a total of 20 points using a VHX6000 at 200x magnification. The average value was used as the interlayer thickness (μm). The surface quality of the molded article was evaluated according to the following criteria.

[0191] C: There are areas not impregnated with resin (dry spots) and twists (undulations) in the reinforcing fibers.

[0192] B: Dry spots, no bumps

[0193] A: No dry spots, no bumps

[0194] <Method for measuring impregnation time and volume fiber content>

[0195] For a laminate for CAI produced according to the above-mentioned "Laminate Production Method," when resin is injected according to the above-mentioned "Fiber-Reinforced Composite Material Molding Method: VaRI Method" or "Fiber-Reinforced Composite Material Molding Method: RTM Method," the time required for the resin to reach the suction hole from the injection hole is defined as the impregnation time (minutes). Furthermore, the volume fiber content (Vf) of the molded article is calculated by dividing the weight of the CF residue after decomposition by the weight of the test piece before decomposition according to the nitric acid decomposition method described in JIS K7075 (1991).

[0196] (Example 1-0)

[0197] An epoxy resin composition was prepared according to the above-mentioned <Method for Preparing an Epoxy Resin Composition> using 100 parts by mass of "SUMIEPOXY (registered trademark)" ELM-434VL (component [C]) as the epoxy resin main agent, 9.5 parts by mass of "KAYAHARD (registered trademark)" AA (component [D]), and 66.4 parts by mass of "Lonzacure (registered trademark)" M-CD EA (component [D]). 20 (180℃) Evaluation method> for Cd 20 The evaluation was conducted at 180°C and the result was 21.0 minutes.

[0198] According to the above-mentioned <Preparation method of thermoplastic resin material> and <Preparation method of nonwoven fabric>, a nonwoven fabric having a unit area weight (Wb) of 5 g / m2 formed of PA6I was prepared. 2The non-woven fabric. The measured melt enthalpy is 0 J / g as determined by the <Method for Measuring the Melt Enthalpy of Thermoplastic Resin Materials> described above, and it is an amorphous resin. The average fiber diameter (Df) is measured by the <Method for Observing the Fiber Diameter of Non-Woven Fabrics> described above, and the result is 40 μm, and the value of Wb / Df becomes 0.13. For this non-woven fabric (component [B]) and the epoxy resin composition (a mixture of component [C] and component [D]), the Rexp(190 °C) measured by the <Method for Evaluating the Expansion Ratio of Non-Woven Fabric Fibers Present in an Epoxy Resin Cured Plate> is 1.05, the Rexp(170 °C) is 2.25, and the value of (Rexp(190 °C) - Rexp(170 °C)) × 5 is 6.00, which is outside the range of condition 3.

[0199] Using "TORAYCA (registered trademark)" T800G-24K-71E as the reinforcing fiber, a reinforcing fiber substrate (component [A]) is produced according to the <Method for Producing a Fiber Reinforced Substrate> described above, a laminate is produced according to the <Method for Producing a Laminate> described above, and according to the <Molding Method of Fiber Reinforced Composite Material: VaRI Method>, molded products for CAI evaluation, OHC evaluation, ILSS evaluation, and thermal cycling durability test are produced at a curing temperature of 180 °C.

[0200] For the obtained molded products, evaluations are carried out according to the <CAI Test Method>, <Room Temperature OHC Test Method>, <Wet Heat OHC Test Method>, <Room Temperature ILSS Test Method>, <Wet Heat ILSS Test Method>, and <Thermal Cycling Durability Test Method> described above. As a result, the CAI strength is 265 MPa, the room temperature OHC strength is 285 MPa, and the wet heat OHC strength is 255 MPa, showing excellent impact resistance and compression characteristics. In addition, the room temperature ILSS strength and the wet heat ILSS strength are 105 MPa and 82 MPa respectively, and the number of cracks after the thermal cycling durability test is 3, which are excellent molded products.

[0201] In addition, the surface quality of the molded product is evaluated according to the <Method for Evaluating Surface Quality and Interlayer Thickness> described above, and the result is judged to be B and good. The impregnation time measured by the <Method for Measuring Impregnation Time and Volume Fiber Content> described above is 21.0 minutes, showing excellent impregnation characteristics. In addition, the Vf of this molded product is 59.5%.

[0202] (Examples 1-1 to 1-4, 1-6 to 1-13, 1-15 to 1-16)

[0203] An epoxy resin composition was prepared by the same method as in Example 1-0, except that the epoxy resin composition was changed as shown in Table 1. Component [B] was prepared by the same method as in Example 1-0, except that the thermoplastic resin material of component [B] was changed as shown in Tables 2 and 3. Furthermore, the melting enthalpy was measured by the same method as in Example 1-0 and the result was 0 J / g, indicating amorphous properties. Cd of each example 20 (180° C.) is 15.7 minutes to 31.0 minutes, and the value of (Rexp(190° C.)−Rexp(170° C.))×5 is 0.75 to 4.50, satisfying Condition 3.

[0204] Fiber-reinforced composite materials were produced using the same method as Example 1-0, using the components listed in Table 2. For each example, CAI strength, room temperature and wet heat ILSS, thermal cycling durability, and room temperature and wet heat OHC were evaluated. The results showed excellent physical properties across all parameters, demonstrating a high balance of compressive strength in wet heat environments, impact resistance, and crack resistance after thermal cycling. Furthermore, the impregnation time for each example was 9.0 to 18.0 minutes, demonstrating excellent impregnation properties during VaRI molding. Furthermore, the surface quality of the molded articles was excellent.

[0205] (Examples 1-5, 1-14, 1-17)

[0206] Epoxy resin compositions were prepared in the same manner as in Example 1-0, except that the epoxy resin composition was changed as shown in Table 1. Component [B] was prepared in the same manner as in Example 1-0, except that the thermoplastic resin material of component [B] was changed as shown in Tables 2 and 3. Melting enthalpy was measured in the same manner as in Example 1-0, and the results were all 0 J / g, indicating that the material was amorphous. Cd of each example 20 The Rexp(190°C) and Rexp(170°C) values ​​are 16.2 to 18.3 minutes, and the value of (Rexp(190°C) - Rexp(170°C)) × 5 is 0.85 to 3.40.

[0207] Fiber-reinforced composite materials were produced according to the aforementioned "Fiber-reinforced Composite Material Molding Method: RTM Method" using the components listed in Tables 2 and 3. For each example, CAI strength, room temperature and wet heat ILSS, thermal cycling durability, and room temperature and wet heat OHC were evaluated. Excellent physical properties were achieved across all parameters. Furthermore, the impregnation time for each example was 5.0 to 6.5 minutes, demonstrating excellent impregnation even during RI molding. Furthermore, the surface quality of the molded products was excellent.

[0208] (Comparative Example 1-1)

[0209] Composition 4 shown in Table 1 was used as the epoxy resin composition, and "Spunfab (registered trademark)" PA1206 (manufactured by Spunfab Ltd.), which is a crystalline nonwoven fabric, was used as component [B]. 20 (180° C.) was 31.0 minutes, but the value of (Rexp(190° C.)−Rexp(170° C.))×5 was 7.00, which was outside the range of Condition 3.

[0210] A fiber-reinforced composite material was produced using the components shown in Table 4 in the same manner as in Example 1-0. The CAI strength, room temperature and wet heat ILSS, thermal cycling durability, and room temperature and wet heat OHC were evaluated. The CAI strength was excellent at 290 MPa, but the wet heat OHC was insufficient at 215 MPa. Furthermore, the impregnation time was increased to 24.0 minutes.

[0211] (Comparative Example 1-2)

[0212] An epoxy resin composition similar to that of Comparative Example 1-1 was prepared except that component [B] was changed to "Spunfab (registered trademark)" PA1209 (manufactured by Spunfab Ltd.). 20 (180° C.) was 31.0 minutes, but the value of (Rexp(190° C.)−Rexp(170° C.))×5 was 0.25, which was outside the range of Condition 3.

[0213] A fiber-reinforced composite material was produced in the same manner as in Comparative Example 1-1, except that component [B] was modified as described above. The CAI strength, room temperature and wet heat ILSS, thermal cycle durability, and room temperature and wet heat OHC were evaluated. The CAI strength was 223 MPa, which was insufficient, and the wet heat OHC was 210 MPa, which was insufficient. Furthermore, the number of cracks generated after the thermal cycle durability test was as high as 15, and the surface quality of the molded article was rated C.

[0214] (Comparative Examples 1-3)

[0215] Composition 10 shown in Table 1 was used as the epoxy resin composition, and the same material as in Example 1-6 was used as component [B]. The value of (Rexp(190°C)-Rexp(170°C))×5 was 0.60, but Cd 20 (180°C) is as short as 14.0, which is outside the range of Condition 2.

[0216] A fiber-reinforced composite material was produced using the same method as in Comparative Example 1-1. The CAI strength, room temperature and wet heat ILSS, thermal cycling durability, and room temperature and wet heat OHC were evaluated. The CAI strength was insufficient at 200 MPa, and the wet heat OHC was insufficient at 230 MPa. Furthermore, the number of cracks incurred after the thermal cycling durability test was as high as 13.

[0217] (Comparative Examples 1-4)

[0218] The epoxy resin composition and component [B] were the components described in Example 1-1 of Patent Document 1 (International Publication No. 2022 / 149591). 20 (180°C) is as short as 3.0, which is outside the range of condition 2. The value of (Rexp(190°C)−Rexp(170°C))×5 is 0.40, which is outside the range of condition 3.

[0219] A fiber-reinforced composite material was produced using the same method as in Comparative Example 1-1. The CAI strength, room temperature and wet heat ILSS, thermal cycling durability, and room temperature and wet heat OHC were evaluated. The CAI strength was good at 250 MPa, but the wet heat OHC strength was insufficient at 230 MPa. Furthermore, Vf was a low 54%.

[0220] (Comparative Examples 1-5)

[0221] Composition 7 shown in Table 1 was used as the epoxy resin composition, and the same materials as in Example 1-3 were used as component [B]. The value of (Rexp(190°C)-Rexp(170°C))×5 was 3.00, but Cd 20 (180℃) increased to 47.5, which is outside the range of condition 2.

[0222] A fiber-reinforced composite material was produced using the same method as in Comparative Example 1-1. CAI strength, room temperature and wet heat ILSS, thermal cycling durability, and room temperature and wet heat OHC were evaluated. While the CAI strength was high at 280 MPa, the wet heat OHC was 210 MPa and the wet heat ILSS strength was 55 MPa, indicating insufficient strength. Furthermore, the surface quality of the molded article was rated C, indicating a low rating.

[0223] (Comparative Examples 1-6)

[0224] Composition 9 shown in Table 1 was used as the epoxy resin composition, and the same materials as in Example 1-6 were used as component [B]. The value of (Rexp(190°C)-Rexp(170°C))×5 was 0.15, and Cd 20 (180°C) was 6.7, which was outside the range of Conditions 3 and 2.

[0225] A fiber-reinforced composite material was produced using the same method as in Comparative Example 1-1. Evaluation of CAI strength, room temperature and wet heat ILSS, thermal cycling durability, and room temperature and wet heat OHC revealed a significantly insufficient CAI strength of 200 MPa, and an insufficient wet heat OHC of 215 MPa. Furthermore, the surface quality of the molded article was rated C, indicating a low level.

[0226] (Example 2-0)

[0227] An epoxy resin composition was prepared according to the above-mentioned <Method for Preparing an Epoxy Resin Composition> using 100 parts by mass of "SUMIEPOXY (registered trademark)" ELM-434VL (component [C]) as the epoxy resin main agent, 9.5 parts by mass of "KAYAHARD (registered trademark)" AA (component [D]), and 66.4 parts by mass of "Lonzacure (registered trademark)" M-CD EA (component [D]). 20 (180℃) Evaluation method> for Cd 20 The evaluation was conducted at 180°C and the result was 21.0 minutes.

[0228] In addition, regarding this epoxy resin composition, E25 was evaluated according to the <Evaluation method of tensile elastic modulus E25 of epoxy resin composition (25°C, 50% RH)>, and the result was 3.83 GPa. According to the <Evaluation method of tensile elastic modulus E82 of epoxy resin composition (wet heat 82°C)>, E82 was evaluated according to the <Evaluation method of tensile elastic modulus E82 of epoxy resin composition>, and the result was 3.15 GPa.

[0229] According to the above-mentioned <Preparation method of thermoplastic resin material> and <Preparation method of nonwoven fabric>, a nonwoven fabric having a unit area weight (Wb) of 5 g / m2 formed of PA6I was prepared. 2 Nonwoven fabric. The melting enthalpy measured according to the above-mentioned <Method for Determining the Melting Enthalpy of Thermoplastic Resin Materials> was 0 J / g, indicating that it was an amorphous resin. Furthermore, the average fiber diameter (Df) measured according to the above-mentioned <Method for Observing the Fiber Diameter of Nonwoven Fabrics> was 40 μm, and the value of Wb / Df was 0.13. For this nonwoven fabric (component [B]), B25 was evaluated according to the <Method for Evaluating the Tensile Modulus B25 of Thermoplastic Resin Materials (Humidity Control at 25°C)> and the result was 2.20 GPa. B82 was evaluated according to the <Method for Evaluating the Tensile Modulus B82 of Thermoplastic Resin Materials (Humidity Control at 82°C)> and the result was 1.10 GPa.

[0230] For the nonwoven fabric (component [B]) and the epoxy resin composition (a mixture of components [C] and [D]), the tensile modulus retention ratio R of the thermoplastic resin material to the epoxy resin composition is <ret Calculation method> Calculate R ret , the result is 0.61, outside the range of Condition 4.

[0231] Using "TORAYCA (registered trademark)" T800G-24K-71E as the reinforcing fiber, the reinforcing fiber substrate (Component [A]) was produced according to the above <Production method of fiber-reinforced substrate>, the laminate was produced according to the above <Production method of laminate>, and according to the above <Molding method of fiber-reinforced composite material: VaRI method>, molded products for CAI evaluation, OHC evaluation, ILSS evaluation, and thermal cycling durability test were produced at a curing temperature of 180°C.

[0232] For the obtained molded products, evaluation was carried out according to the above <CAI test method>, <Room temperature OHC test method>, <Wet heat OHC test method>, <Room temperature in-plane shear test method>, <Wet heat in-plane shear test method>, <Room temperature ILSS test method>, <Wet heat ILSS test method>, and <Thermal cycling durability test method>. As a result, the CAI strength was 265 MPa, the room temperature OHC strength was 285 MPa, and the wet heat OHC strength was 255 MPa, showing excellent impact resistance and compression characteristics. In addition, the room temperature in-plane shear elastic modulus and the wet heat in-plane shear elastic modulus were 5.0 GPa and 3.5 GPa respectively, and the room temperature ILSS strength and the wet heat ILSS strength were 105 MPa and 82 MPa respectively, showing excellent in-plane shear characteristics. Also, the number of cracks after the thermal cycling durability test was 3, and it was an excellent molded product.

[0233] In addition, the surface quality of the molded product was evaluated according to the above <Evaluation method of surface quality and interlayer thickness>, and the result was judged as B and good. The impregnation time measured according to the above <Measurement method of impregnation time and volume fiber content> was 21.0 minutes, showing excellent impregnation characteristics. In addition, the Vf of this molded product was 59.0%.

[0234] (Examples 2-1 to 2-4, 2-6 to 2-11)

[0235] As shown in Table 1, the epoxy resin composition was changed, and except for this, the epoxy resin composition was produced by the same method as in Example 2-0. As shown in Tables 5 and 6, the thermoplastic resin material of Component [B] was changed, and except for this, Component [B] was produced by the same method as in Example 2-0. The melt enthalpy was measured by the same method as in Example 2-0, and the results were all 0 J / g, which was an amorphous material. The Cd of each example [[ID=J]] 20 (180°C) was 15.7 minutes to 31.0 minutes, and the R ret value was 0.71 to 1.13 and satisfied Condition 4.

[0236] Fiber-reinforced composite materials were produced using the same method as Example 2-0, using the components listed in Tables 5 and 6. For each example, CAI strength, in-plane shear modulus at room temperature and under wet heat, ILSS at room temperature and under wet heat, thermal cycling durability, and OHC at room temperature and under wet heat were evaluated. The results showed excellent physical properties across all parameters, demonstrating a high balance of compressive strength under wet heat, impact resistance, and crack resistance after thermal cycling. Furthermore, the impregnation time for each example was 9.0 to 18.0 minutes, demonstrating excellent impregnation properties during VaRI molding. Furthermore, the surface quality of the molded articles was excellent.

[0237] (Examples 2-5, 2-14, 2-17)

[0238] An epoxy resin composition was prepared by the same method as in Example 2-0. Component [B] was prepared by the same method as in Example 2-0, except that the thermoplastic resin material of component [B] was changed as shown in Tables 5 and 6. Melting enthalpy was measured by the same method as in Example 2-0, and the results were all 0 J / g, indicating that the material was amorphous. Cd of each example 20 (180℃) is 16.2 minutes to 21.0 minutes, R ret The value is 0.93~1.13.

[0239] Fiber-reinforced composite materials were produced using the components listed in Table 5 according to the "Fiber-reinforced Composite Material Molding Method: RTM Method" described above. CAI strength, in-plane shear modulus at room temperature and under wet heat, ILSS at room temperature and under wet heat, thermal cycling durability, and OHC at room temperature and under wet heat were evaluated. Excellent physical properties were achieved across all parameters. Furthermore, the impregnation time during molding was 4.0 to 6.5 minutes, demonstrating excellent impregnation even during RTM molding. Furthermore, the surface quality of the molded product was excellent.

[0240] (Examples 2-12, 2-13, 2-15, 2-16)

[0241] Epoxy resin compositions were prepared in the same manner as in Example 2-1, except that the epoxy resin composition was changed as shown in Table 1. Component [B] was prepared in the same manner as in Example 2-1, except that the thermoplastic resin material of component [B] was changed as shown in Table 6. The melting enthalpy was measured in the same manner as in Example 2-0, and the results were all 0 J / g, indicating that the material was amorphous. Cd of each example 20 (180℃) is 16.2 minutes to 17.5 minutes, R ret The value is 0.95~1.07.

[0242] Fiber-reinforced composite materials were produced using the same method as Example 2-0, using the components listed in Table 6. For each example, CAI strength, room temperature and wet heat in-plane shear modulus, room temperature and wet heat ILSS, thermal cycling durability, and room temperature and wet heat OHC were evaluated. The results showed excellent physical properties across all parameters, demonstrating a high balance of compressive strength in wet heat environments, impact resistance, and crack resistance after thermal cycling. In these examples, the wet heat OHC was particularly high, reaching 304 to 315 MPa. Furthermore, the wet heat in-plane shear modulus was 4.3 to 4.5 GPa, and the wet heat ILSS was 102 to 105 MPa, demonstrating high shear properties. Furthermore, the impregnation time for each example was 10.5 to 12.0 minutes, demonstrating excellent impregnation during VaRI molding. Furthermore, the surface quality of the molded products was excellent.

[0243] (Comparative Example 2-1)

[0244] Composition 4 shown in Table 1 was used as the epoxy resin composition, and PA6 / 12 (20:80) was used as the thermoplastic resin material of component [B]. 20 (180℃) is 31.0 minutes, but R ret It is 0.45 and is outside the range of condition 3.

[0245] A fiber-reinforced composite material was produced using the components shown in Table 7 in the same manner as in Example 2-0. The CAI strength, in-plane shear modulus at room temperature and under wet heat, ILSS at room temperature and under wet heat, thermal cycling durability, and OHC at room temperature and under wet heat were evaluated. The CAI strength was excellent at 290 MPa, but the OHC at wet heat was 215 MPa, the in-plane shear modulus at wet heat was 3.0 GPa, and the ILSS at wet heat was 60 MPa, indicating inadequate performance. Furthermore, the impregnation time was increased to 24.0 minutes.

[0246] (Comparative Example 2-2)

[0247] The same epoxy resin composition as in Comparative Example 2-1 was prepared except that the thermoplastic resin material of component [B] was PA6 / 12 (80:20). 20 (180℃) is 31.0 minutes, but R ret It is 0.69 and is outside the range of condition (4).

[0248] A fiber-reinforced composite material was produced using the same method as in Comparative Example 2-1, except for the aforementioned modification of component [B]. The CAI strength, in-plane shear modulus at room temperature and under wet heat, ILSS at room temperature and under wet heat, thermal cycling durability, and OHC at room temperature and under wet heat were evaluated. The CAI strength was insufficient at 223 MPa, while the OHC at wet heat was 210 MPa, the in-plane shear modulus at wet heat was 3.1 GPa, and the ILSS at wet heat was 62 MPa, indicating inadequacy. Furthermore, the number of cracks incurred after the thermal cycling durability test was as high as 15, and the surface quality of the molded article was rated C.

[0249] (Comparative Example 2-3)

[0250] Composition 10 shown in Table 1 was used as the epoxy resin composition, and the same materials as in Example 2-6 were used as component [B]. ret The value of Cd is 1.10, but 20 (180°C) is as short as 14.0, which is outside the range of condition (2).

[0251] A fiber-reinforced composite material was produced using the same method as in Comparative Example 2-1. The CAI strength, in-plane shear modulus at room temperature and under wet heat, ILSS at room temperature and under wet heat, thermal cycling durability, and OHC at room temperature and under wet heat were evaluated. The CAI strength was found to be insufficient at 200 MPa, and the OHC at wet heat was found to be insufficient at 230 MPa. Furthermore, the number of cracks incurred after the thermal cycling durability test was as high as 13.

[0252] (Comparative Examples 2-4)

[0253] The epoxy resin composition and component [B] were the components described in Example 1 of Patent Document 1 (International Publication No. 2022 / 149591). ret The value of Cd is 1.07, but 20 (180°C) is as short as 3.0, which is outside the range of condition (2).

[0254] A fiber-reinforced composite material was produced using the same method as in Comparative Example 2-1. The CAI strength, room temperature and wet heat ILSS, room temperature and wet heat in-plane shear modulus, thermal cycling durability, and room temperature and wet heat OHC were evaluated. The CAI strength was 250 MPa, which was satisfactory. However, the wet heat OHC strength was 230 MPa, the wet heat in-plane shear modulus was 3.2 GPa, and the wet heat ILSS was 58 MPa, which were insufficient. Furthermore, Vf was a low 54%.

[0255] (Comparative Examples 2-5)

[0256] Composition 7 shown in Table 1 was used as the epoxy resin composition, and the same materials as in Example 2-3 were used as component [B].ret The value of Cd is 1.20, but 20 (180°C) increased to 47.5, which is outside the range of condition (2).

[0257] A fiber-reinforced composite material was produced using the same method as in Comparative Example 2-1. The CAI strength, in-plane shear modulus at room temperature and under wet heat, ILSS at room temperature and under wet heat, thermal cycling durability, and OHC at room temperature and under wet heat were evaluated. While the CAI strength was high at 280 MPa, the OHC under wet heat was insufficient at 210 MPa, the in-plane shear modulus under wet heat was 3.0 GPa, and the ILSS strength under wet heat was 55 MPa. Furthermore, the surface quality of the molded article was rated C, which was considered low.

[0258] (Comparative Example 2-6)

[0259] Composition 9 shown in Table 1 was used as the epoxy resin composition, and the same materials as in Example 2-6 were used as component [B]. ret The value of Cd is 0.95, but 20 (180°C) was 6.7, which was outside the range of condition (2).

[0260] A fiber-reinforced composite material was produced using the same method as in Comparative Example 2-1. The CAI strength, room temperature and wet heat in-plane shear modulus, room temperature and wet heat ILSS, thermal cycling durability, and room temperature and wet heat OHC were evaluated. The CAI strength was significantly insufficient at 200 MPa, while the wet heat OHC was 215 MPa, the hot in-plane shear modulus was 3.3 GPa, and the wet heat ILSS strength was 65 MPa, indicating inadequacy. Furthermore, the surface quality of the molded article was rated C, indicating a low rating.

[0261] (Example 3-0)

[0262] An epoxy resin composition was prepared according to the above-mentioned <Method for Preparing an Epoxy Resin Composition> using 100 parts by mass of "SUMIEPOXY (registered trademark)" ELM-434VL (component [C]) as the epoxy resin main agent, 9.5 parts by mass of "KAYAHARD (registered trademark)" AA (component [D]), and 66.4 parts by mass of "Lonzacure (registered trademark)" M-CD EA (component [D]). 20 (180℃) Evaluation method> for Cd 20 The evaluation was conducted at 180°C and the result was 21.0 minutes.

[0263] According to the above-mentioned <Preparation method of thermoplastic resin material> and <Preparation method of nonwoven fabric>, a nonwoven fabric having a unit area weight (Wb) of 5 g / m2 formed of PA6I was prepared.2 The non-woven fabric. The melting enthalpy measured according to the above <Method for Measuring the Melting Enthalpy of Thermoplastic Resin Materials> is 0 J / g, and it is an amorphous resin. In addition, the average fiber diameter (Df) is measured according to the above <Method for Observing the Fiber Diameter of Non-woven Fabrics>, and the result is 40 μm, and the value of Wb / Df becomes 0.13.

[0264] Using "TORAYCA (registered trademark)" T800G-24K-71E as the reinforcing fiber, the reinforcing fiber substrate (component [A]) as a unidirectional sheet is produced according to the above <Method for Producing Fiber Reinforced Substrate>, the laminate for the compressive stress test is produced according to the above <Method for Producing Laminate>, and the compressive stress is measured according to the above <Method for Compressive Stress Test>. As a result, σ160 is 0.25 MPa, σ190 is 0.52 MPa, and σ190 / σ160 is 0.48, which is outside the range of Condition 5.

[0265] The laminate is produced according to the above <Method for Producing Laminate>, and according to the above <Molding Method of Fiber Reinforced Composite Material: VaRI Method>, molded products for CAI evaluation, OHC evaluation, ILSS evaluation, and thermal cycling durability test are produced at a curing temperature of 180°C.

[0266] For the obtained molded products, evaluation is carried out according to the above <CAI Test Method>, <Room Temperature OHC Test Method>, <Wet Heat OHC Test Method>, <Room Temperature ILSS Test Method>, <Wet Heat ILSS Test Method>, and <Thermal Cycling Durability Test Method>. As a result, the CAI strength is 265 MPa, the room temperature OHC strength is 285 MPa, and the wet heat OHC strength is 255 MPa, showing excellent impact resistance and compressive characteristics. In addition, the room temperature ILSS strength and the wet heat ILSS strength are 105 MPa and 82 MPa respectively, and the number of cracks after the thermal cycling durability test is 3, which are excellent molded products.

[0267] In addition, the surface quality of the molded product is evaluated according to the above <Evaluation Method for Surface Quality and Interlayer Thickness>, and the result is judged to be B and good. The impregnation time measured according to the above <Measurement Method of Impregnation Time and Volume Fiber Content> is 21.0 minutes, showing excellent impregnation characteristics. In addition, the Vf of this molded product is 59.5%.

[0268] (Examples 3-2 to 3-4, 3-6 to 3-12, 3-14, 3-15)

[0269] The epoxy resin composition was prepared in the same manner as in Example 3-0, except that the composition of the epoxy resin was changed as shown in Table 1. The component [B] was prepared in the same manner as in Example 3-0, except that the thermoplastic resin material and the weight per unit area of ​​the component [B] were changed as shown in Tables 8 and 9. The melting enthalpy was measured in the same manner as in Example 3-0, and the results were all 0 J / g, indicating that the material was an amorphous material. The type of reinforcing fiber, the form of the reinforcing fiber substrate, and the weight per unit area of ​​the component [A] were changed as shown in Tables 8 and 9. The laminate for compression testing was prepared in the same manner as in Example 3-1, using the components listed in Tables 8 and 9. Cd of each example 20 (180°C) is 15.7 minutes to 31.0 minutes, σ190 / σ160 is 0.54 to 0.84, and condition 5 is satisfied.

[0270] Fiber-reinforced composite materials were produced using the same method as in Example 3-0, using the components listed in Tables 8 and 9. For each example, CAI strength, room temperature and wet heat ILSS, thermal cycling durability, and room temperature and wet heat OHC were evaluated. The results showed excellent physical properties across all parameters, demonstrating a high balance of compressive strength in wet heat environments, impact resistance, and crack resistance after thermal cycling. Furthermore, the impregnation time for each example was 9.0 to 18.0 minutes, demonstrating excellent impregnation properties during VaRI molding. Furthermore, the surface quality of the molded articles was excellent.

[0271] (Examples 3-5, 3-13, 3-16 to 3-19)

[0272] The epoxy resin composition was changed as shown in Table 1, and the epoxy resin composition was prepared using the same method as in Example 3-0. The thermoplastic resin material of component [B] was changed as shown in Tables 8 and 9, and the component [B] was prepared using the same method as in Example 3-0. The melting enthalpy was measured using the same method as in Example 3-0, and the results were all 0 J / g, indicating that it was an amorphous material. The type of reinforcing fiber, the form of the reinforcing fiber substrate, and the unit area weight of component [A] were changed as shown in Tables 8 and 9, and the laminate for compression testing was prepared using the components described in Tables 8 and 9 using the same method as in Example 3-1. Cd of each example 20 (180°C) is 16.2 minutes to 18.3 minutes, and σ190 / σ160 is 0.68 to 0.84.

[0273] Fiber-reinforced composite materials were produced according to the aforementioned "Fiber-reinforced Composite Material Molding Method: RTM Method" using the components listed in Tables 8 and 9. For each example, CAI strength, room temperature and wet heat ILSS, thermal cycling durability, and room temperature and wet heat OHC were evaluated. Excellent physical properties were achieved across all parameters. Furthermore, the impregnation time for each example was 5.0 to 6.5 minutes, demonstrating excellent impregnation even during RI molding. Furthermore, the surface quality of the molded products was excellent.

[0274] (Comparative Example 3-1)

[0275] Composition 4 shown in Table 1 was used as the epoxy resin composition, and "Spunfab (registered trademark)" PA1206 (manufactured by Spunfab Ltd.), which is a crystalline nonwoven fabric, was used as component [B]. 20 (180°C) was 31.0 minutes, but the value of σ190 / σ160 was 0.30, which was outside the range of condition (5).

[0276] A fiber-reinforced composite material was produced using the components shown in Table 10 in the same manner as in Example 3-0. The CAI strength, room temperature and wet heat ILSS, thermal cycling durability, and room temperature and wet heat OHC were evaluated. The CAI strength was excellent at 290 MPa, but the wet heat OHC was insufficient at 215 MPa. Furthermore, the impregnation time was increased to 24.0 minutes.

[0277] (Comparative Example 3-2)

[0278] An epoxy resin composition similar to that of Comparative Example 3-1 was prepared except that component [B] was changed to "Spunfab (registered trademark)" PA1209 (manufactured by Spunfab Ltd.). 20 (180°C) was 31.0 minutes, but the value of σ190 / σ160 was 0.47, which was outside the range of condition (5).

[0279] A fiber-reinforced composite material was produced using the same method as in Comparative Example 3-1, except for the aforementioned modification of component [B]. The CAI strength, room temperature and wet heat ILSS, thermal cycle durability, and room temperature and wet heat OHC were evaluated. The CAI strength was 223 MPa, which was insufficient, and the wet heat OHC was 210 MPa, which was insufficient. Furthermore, the number of cracks generated after the thermal cycle durability test was as high as 15, and the surface quality of the molded article was also rated C.

[0280] (Comparative Example 3-3)

[0281] Composition 10 shown in Table 1 was used as the epoxy resin composition, and the same materials as in Examples 3-6 were used as component [B]. The value of σ190 / σ160 was 0.81, but Cd 20 (180°C) is as short as 14.0, which is outside the range of condition (2).

[0282] A fiber-reinforced composite material was produced using the same method as in Comparative Example 3-1. The CAI strength, room temperature and wet heat ILSS, thermal cycling durability, and room temperature and wet heat OHC were evaluated. The CAI strength was insufficient at 200 MPa, and the wet heat OHC was insufficient at 230 MPa. Furthermore, the number of cracks incurred after the thermal cycling durability test was as high as 13.

[0283] (Comparative Examples 3-4)

[0284] The epoxy resin composition and component [B] were the components described in Example 1 of Patent Document 1 (International Publication No. 2022 / 149591). The value of σ190 / σ160 was 0.81, but Cd 20 (180°C) is as short as 3.0, which is outside the range of condition (2).

[0285] A fiber-reinforced composite material was produced using the same method as in Comparative Example 3-1. Evaluation of CAI strength, room temperature and wet heat ILSS, thermal cycling durability, and room temperature and wet heat OHC revealed a favorable CAI strength of 250 MPa, but an insufficient wet heat OHC strength of 230 MPa. Furthermore, Vf was a low 54%.

[0286] (Comparative Examples 3-5)

[0287] Composition 7 shown in Table 1 was used as the epoxy resin composition, and the same material as in Example 3-3 was used as component [B]. The value of σ190 / σ160 was 0.81, but Cd 20 (180°C) grew to 47.5, which was outside the range of condition (2).

[0288] A fiber-reinforced composite material was produced using the same method as in Comparative Example 3-1. CAI strength, room temperature and wet heat ILSS, thermal cycling durability, and room temperature and wet heat OHC were evaluated. While the CAI strength was high at 280 MPa, the wet heat OHC was 210 MPa and the wet heat ILSS strength was 55 MPa, indicating insufficient strength. Furthermore, the surface quality of the molded article was rated C, indicating a low rating.

[0289] (Comparative Examples 3-6)

[0290] Composition 9 shown in Table 1 was used as the epoxy resin composition, and the same materials as in Examples 3-6 were used as component [B]. The value of σ190 / σ160 was 0.81, but Cd 20 (180°C) is 6.7, which is outside the range of condition (2).

[0291] A fiber-reinforced composite material was produced using the same method as in Comparative Example 3-1. Evaluation of CAI strength, room temperature and wet heat ILSS, thermal cycling durability, and room temperature and wet heat OHC revealed a significantly insufficient CAI strength of 200 MPa, and an insufficient wet heat OHC of 215 MPa. Furthermore, the surface quality of the molded article was rated C, indicating a low level.

[0292] [Table 1]

[0293]

[0294] [Table 2]

[0295]

[0296] [Table 3]

[0297]

[0298] [Table 4]

[0299]

[0300] [Table 5]

[0301]

[0302] [Table 6]

[0303]

[0304] [Table 7]

[0305]

[0306] [Table 8]

[0307]

[0308] [Table 9]

[0309]

[0310] [Table 10]

[0311]

[0312] In addition, the unit of each component in the table is part by mass.

[0313] Industrial applicability

[0314] The fiber-reinforced composite molding material of the present invention has excellent impregnation properties during resin injection molding. The fiber-reinforced composite material obtained by thermal curing can achieve high levels of compressive strength, impact resistance, and crack resistance after hot and cold cycles in a hot and humid environment. Therefore, it can be suitably used in aircraft components, especially large primary structural components.

[0315] Specifically, it can be preferably used in a wide range of structural materials, including aircraft components such as fuselages, main wings, tail planes, movable surfaces, fairings, aircraft engine covers, doors, seats, and interior materials; spacecraft components such as engine cases and main wings; satellite components such as structural parts and antennas; automotive components such as outer panels, chassis, aerodynamic components, and seats; railway vehicle components such as structural parts and seats; and ship components such as hulls and seats. The fiber-reinforced composite material molding material of the present invention is particularly suitable for aircraft components, especially large primary structural components, due to its high balance of impact resistance and compressive strength under wet and hot conditions, as well as its crack resistance against thermal cycling. Furthermore, the fiber-reinforced composite material exhibits excellent impregnation properties during resin injection molding.

Claims

1. A molding material for a fiber-reinforced composite material, comprising: impregnating a laminate comprising a component [B] incorporated between any of the layers of a plurality of layers of a component [A] with an epoxy resin composition comprising the components [C] and [D], wherein the molding material for a fiber-reinforced composite material satisfies both the following conditions 1 and 2. [A]: Reinforced fiber substrate, [B]: Non-woven fabric, [C]: Epoxy resin main agent, [D]: Amine compound; Condition 1: Component [B] is formed of an amorphous resin material; Condition 2: Time Cd for the epoxy resin composition containing components [C] and [D] to reach a degree of cure of 20% at 180°C 20 (180°C) for 15 to 45 minutes.

2. The fiber-reinforced composite material molding material according to claim 1, which satisfies the following condition 3: Condition 3: (i) The ratio of the fiber diameter of component [B] in a resin cured plate obtained by impregnating component [B] with the epoxy resin composition and thermally curing at 190°C to the fiber diameter before thermal curing is defined as Rexp(190°C); (ii) The ratio of the fiber diameter of component [B] in a resin cured plate obtained by impregnating component [B] with the epoxy resin composition and thermally curing at 170°C to the fiber diameter before thermal curing is defined as Rexp(170°C); Rexp(190°C) and Rexp(170°C) are related by the following formula (1): 0.5<(Rexp(190℃)-Rexp(170℃))×5<5.0···(1).

3. The fiber-reinforced composite material molding material according to claim 1, which satisfies the following condition 4: Condition 4: (i) the tensile modulus B82 (humidity controlled at 82°C) and the tensile modulus B25 (humidity controlled at 25°C) of component [B], and (ii) the tensile modulus E82 (humid heat 82°C) and the tensile modulus E25 (25°C, 50% RH) of an epoxy resin cured plate obtained by heat-curing an epoxy resin composition containing components [C] and [D] at 180°C, are in the relationship expressed by the following formula (2). 0.7< R ret =(B82 / B25) / (E82 / E25)<1.2· · · (2)。 4. The fiber-reinforced composite material molding material according to claim 1, which satisfies the following condition 5: Condition 5: When the laminate is compressed in the out-of-plane direction, the compressive stress at 160°C (σ160: MPa) and the compressive stress at 190°C (σ190: MPa) are in the relationship of the following formula (3): 0.5<(σ190 / σ160)<1.0···(3).

5. The fiber-reinforced composite material molding material according to any one of claims 1 to 4, wherein The amorphous resin material constituting component [B] is amorphous polyamide.

6. The fiber-reinforced composite material molding material according to any one of claims 1 to 4, wherein The deflection temperature under load of the amorphous resin material constituting component [B] is within a range of 100°C to 160°C.

7. The fiber-reinforced composite material molding material according to any one of claims 1 to 4, wherein The value (Wb / Df) obtained by dividing the weight per unit area (Wb) of the component [B] by the number average fiber diameter (Df) of the component [B] is in the range of 0.15 to 0.

60. 8 . A fiber-reinforced composite material obtained by thermally curing the molding material for a fiber-reinforced composite material according to claim 1 .

9. The fiber-reinforced composite material according to claim 8, wherein: In a fiber-reinforced composite material formed by thermally curing the fiber-reinforced composite material molding material according to any one of claims 1 to 4 at 180°C for 2 hours, the value (Ti / Df) obtained by dividing the thickness between reinforcing fiber layers (Ti) by the number average fiber diameter (Df) of component [B] is in the range of 0.7 to 1.5.

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