Laminate

Abstract

To provide an FRP laminate formed by combining a unidirectional reinforced fiber and a reinforced fiber woven fabric which achieves high interlaminar toughness and a small crimp angle of the reinforced fiber woven fabric.SOLUTION: A laminate includes a layer (hereinafter referred to as unidirectional reinforced fiber layer) of a fiber-reinforced composite material containing a reinforced fiber that is aligned in one direction and a matrix resin, and a layer (hereinafter referred to as reinforced fiber woven fabric layer) of a fiber-reinforced composite material containing a reinforced fiber woven fabric and a matrix resin, the reinforced fiber woven fabric layer laminated adjacent to the surface of the unidirectional reinforced fiber layer, wherein a resin layer exists between the unidirectional reinforced fiber in at least the one unidirectional reinforced fiber layer, and the reinforced fiber woven fabric of at least the one reinforced fiber woven fabric layer adjacent to the surface of the unidirectional reinforced fiber; polymer particles are contained in the resin layer and a resin rich part and a fiber rich part are formed therein; and a particle ratio of the polymer particles in the fiber rich part is higher than a particle ratio of the polymer particles in the resin rich part.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a laminate comprising a layer of a fiber-reinforced composite material containing unidirectionally aligned reinforcing fibers, and a layer of a fiber-reinforced composite material containing a reinforcing fiber woven fabric laminated on the surface of the layer of the fiber-reinforced composite material. [Background technology]

[0002] In recent years, fiber-reinforced composites (FRPs), which use carbon fiber, aramid fiber, and other reinforcing fibers, have been used in a variety of applications, including structural materials for aircraft and automobiles, sports equipment such as tennis rackets, golf shafts, and fishing rods, and general industrial applications, taking advantage of their high specific strength and specific modulus.

[0003] FRP is manufactured using prepreg, a sheet-like intermediate material in which reinforcing fibers are impregnated with uncured matrix resin, and then curing the prepreg, or resin transfer molding, in which liquid resin is poured into reinforcing fibers placed in a mold and then cured.Of these manufacturing methods, in the prepreg method, multiple sheets of prepreg are usually stacked together and then heated and pressurized to obtain an FRP molded product.

[0004] In particular, for structural applications such as aircraft and automobiles, after manufacturing FRP with a layer of FRP containing unidirectionally aligned reinforcing fibers and a matrix resin (hereinafter referred to as unidirectional reinforcing fiber layer or unidirectional FRP), the FRP may be drilled for purposes such as joining to other molded products. In this case, if the reinforcing fibers on the surface of the FRP are aligned in one direction, the reinforcing fibers cut during processing can peel off, causing fraying and a poor surface appearance.

[0005] To address this issue, it is known that laminating a layer of FRP containing woven reinforcing fibers and a matrix resin (hereinafter referred to as woven reinforcing fiber layer or woven FRP) on the surface of the unidirectional FRP makes it less likely to develop splinters than when the FRP is aligned in one direction. Therefore, when manufacturing FRP that requires drilling, woven FRP is often used on the surface (Patent Document 1).

[0006] One method for suppressing delamination is to form a resin layer between layers and place polymer particles within the resin layer. It has been reported that in FRPs made only of unidirectional reinforcing fibers, placing polymer particles between the layers increases energy absorption when a crack propagates between the layers, thereby achieving high interlaminar toughness (Patent Documents 2 to 4). Note that, to achieve high interlaminar toughness, it is necessary to increase the proportion of polymer particles within the resin layer. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-126557 [Patent Document 2] Special Publication No. 2010-505990 [Patent Document 3] Japanese Patent Application Publication No. 2018-24879 [Patent Document 4] Special Publication No. 2017-505844 Summary of the Invention [Problem to be solved by the invention]

[0008] In the invention described in Patent Document 1, in an FRP made by combining a reinforcing fiber woven fabric and unidirectional reinforcing fibers, there is a difference in the linear expansion coefficient in the non-fiber direction between the reinforcing fiber woven fabric and the unidirectional reinforcing fibers, which causes residual stress to occur between the woven fabric FRP and the unidirectional FRP under room temperature conditions. Furthermore, there is a difference in the elastic modulus, which tends to cause peeling (hereinafter referred to as interlayer delamination) between the reinforcing fiber woven fabric and the unidirectional reinforcing fibers during drilling.

[0009] Regarding the inventions described in Patent Documents 2 to 4, first, FRP laminates formed by combining woven reinforcing fiber fabrics and unidirectional reinforcing fibers are used as structural materials, and therefore require tensile strength in addition to interlaminar toughness. However, compared to unidirectional FRPs, woven FRPs generally have lower elongation at break. Therefore, the weak point in the strength of FRPs formed by combining woven reinforcing fiber fabrics and unidirectional reinforcing fibers, i.e., the fracture origin, is usually located in the woven FRP. Therefore, in order to increase the strength of FRPs formed by combining woven reinforcing fiber fabrics and unidirectional reinforcing fibers, it is important to increase the elongation at break of the woven FRP.

[0010] Next, one of the important parameters governing the breaking elongation of woven FRP is the angle of bending of the reinforcing fibers (hereinafter referred to as the crimp angle; the larger the crimp angle, the greater the degree of bending). Reinforced fiber woven fabrics are composed of warp and weft yarns, and the reinforcing fibers bend out of plane at the region where the warp and weft yarns intersect. FRP with bent reinforcing fibers generates shear stress when subjected to a tensile load in the same direction as the fiber orientation, resulting in a lower breaking elongation than FRP with unbent reinforcing fibers. Furthermore, a larger crimp angle of a reinforcing fiber woven fabric increases the acting shear stress, resulting in a greater decrease in the breaking elongation of the woven FRP. Therefore, one method for improving the breaking elongation of woven FRP is to reduce the crimp angle of the woven FRP. Another method for reducing the crimp angle of woven FRP is to reduce the interlayer thickness of the resin pool (hereinafter referred to as the resin-rich region) that occurs at the region where the warp and weft yarns intersect.

[0011] However, as in the inventions described in Patent Documents 2 to 4, when polymer particles are uniformly arranged at a high particle ratio within the interlayer resin layer in order to achieve high interlayer toughness, there is a problem in that the polymer particles in the resin-rich portion increase in number, resulting in a thick interlayer thickness in the resin-rich portion. This increases the crimp angle and reduces the breaking elongation of the woven FRP. On the other hand, in order to reduce the crimp angle of the woven FRP in order to improve the breaking elongation of the woven FRP, it is necessary to reduce the particle ratio of polymer particles in the resin layer and reduce the interlayer thickness in the resin-rich portion, which makes it difficult to achieve high interlayer toughness. Therefore, there is a trade-off between interlayer toughness and the crimp angle of the woven FRP, making it difficult to achieve both.

[0012] An object of the present invention is to provide an FRP laminate comprising a combination of unidirectional reinforcing fibers and a reinforcing fiber fabric, which has both high interlaminar toughness and a small crimp angle of the reinforcing fiber fabric. [Means for solving the problem]

[0013] The laminate comprises a layer of fiber-reinforced composite material (hereinafter referred to as the unidirectional reinforcing fiber layer) containing reinforcing fibers aligned in one direction and a matrix resin, and a layer of fiber-reinforced composite material (hereinafter referred to as the reinforcing fiber fabric layer) laminated adjacent to the surface of the unidirectional reinforcing fiber layer, containing a reinforcing fiber fabric and a matrix resin, wherein a resin layer is present between the unidirectional reinforcing fibers in at least one unidirectional reinforcing fiber layer and the reinforcing fiber fabric in at least one reinforcing fiber fabric layer adjacent to the surface of the unidirectional reinforcing fiber layer, the resin layer contains polymer particles, and a resin-rich portion and a fiber-rich portion are formed, and the particle ratio of the polymer particles in the fiber-rich portion is higher than the particle ratio of the polymer particles in the resin-rich portion. [Effects of the Invention]

[0014] According to the present invention, it is possible to provide an FRP laminate that combines unidirectional reinforcing fibers and reinforcing fiber fabrics, and that achieves both high interlaminar toughness and a small crimp angle of the reinforcing fiber fabrics. DETAILED DESCRIPTION OF THE INVENTION

[0015] The present invention will be described in more detail below.

[0016] The FRP laminate of the present invention is typically formed by laminating a prepreg comprising a reinforcing fiber woven fabric and a matrix resin onto the surface of a prepreg comprising unidirectionally aligned reinforcing fibers and a matrix resin, followed by curing. Furthermore, a resin layer comprising a matrix resin is formed between the unidirectional reinforcing fibers and the reinforcing fiber woven fabric, and polymer particles are disposed in the resin layer. Furthermore, in the resin layer, the particle ratio of the resin-rich portion (described below) is lower than the particle ratio of the fiber-rich portion (described below). <Material> (reinforced fiber) Unidirectional reinforcing fibers are generally used as reinforcing fiber bundles, consisting of numerous individual fibers. For example, in the case of carbon fiber, a tape-like assembly of approximately 1,000 to 1,000,000 individual fibers is typically called a "tow." These tows can be arranged to produce a sheet-like reinforcing fiber bundle. Reinforcing fibers aligned in one direction along their longitudinal axis are called unidirectional reinforcing fibers, while fibers aligned vertically and horizontally are called woven reinforcing fibers. Unidirectional materials are used when the mechanical properties of FRP are prioritized, while woven reinforcing fibers tend to be used when suppressing burrs during drilling or when fabricating composite shapes. Examples of reinforcing fiber fabrics include plain weave, twill weave, and satin. Other options include knitted and braided fabrics.

[0017] The reinforcing fibers used in the present invention include carbon fibers, glass fibers, aramid fibers, boron fibers, PBO fibers, high-strength polyethylene fibers, alumina fibers, and silicon carbide fibers. Two or more of these fibers may be mixed. In particular, for applications requiring lightweight and high-strength materials, carbon fibers are suitable due to their excellent specific modulus and specific strength.

[0018] Commercially available carbon fibers for unidirectional reinforcing fibers include "TORAYCA (registered trademark)" T800G-24K, "TORAYCA (registered trademark)" T800S-24K, "TORAYCA (registered trademark)" T700G-24K, "TORAYCA (registered trademark)" T300-3K, and "TORAYCA (registered trademark)" T700S-12K (all manufactured by Toray Industries, Inc.).

[0019] Commercially available carbon fibers for reinforcing fiber fabrics include Toray Industries, Inc.'s "Torayca (registered trademark)" cloth C06142, C06347B, C05642, CM6644G, etc., HEXCEL's "HexForce (registered trademark)" Fabrics and "PrimeTex (registered trademark)" 84, G0801, XAGP282P, 43195, G0939, G0803, 43364, XSGP196P, Examples of suitable nonwoven fabrics, mats, and papers include SGP203CS, XC1400, 48200, 48287, and 46150, Injetex® Fabrics GB201, G0986, and G0926, carbon fiber and glass fiber hybrid fabrics G1088, G0874, G0973, and 43743, aramid fiber fabrics 20796 and 21263, and quartz fabrics 610 and 593. Examples of suitable nonwoven fabrics, mats, and paper include Toray Industries, Inc.'s Torayca® Mats B030, B050, and BV03, and Olivest Co., Ltd.'s Carbolite® Mats CEO-030, CBP-030, and ZX-020. (matrix resin) The matrix resin is a thermosetting resin composition, and the type is not particularly limited, and any thermosetting resin composition containing as a main component an epoxy resin, a phenolic resin, an unsaturated vinyl ester resin, an unsaturated polyester resin, a bismaleimide resin, a bismaleimide triazine resin, a cyanate ester resin, a benzoxazine resin, or the like can be suitably used.

[0020] In particular, epoxy resins have good adhesive properties with reinforcing fibers, and are therefore particularly suitable for use in obtaining FRP with excellent strength. The epoxy resin in the present invention preferably contains a tri- or higher functional epoxy resin from the viewpoint of improving heat resistance and elastic modulus. As the tri- or higher functional epoxy resin, it is preferable to use a glycidyl amine type epoxy resin or a glycidyl ether type epoxy resin.

[0021] The use of a trifunctional or higher glycidylamine-type epoxy resin is more preferable in that it improves the interlaminar toughness of the laminate and the elastic modulus of the matrix resin. In a trifunctional or higher glycidylamine-type epoxy resin, the number of functional groups is preferably 3 to 7, more preferably 3 to 4. If the number of functional groups is too large, the matrix resin becomes brittle after curing, which may impair interlaminar toughness. Examples of such epoxy resins include diaminodiphenylmethane-type, diaminodiphenylsulfone-type, aminophenol-type, metaxylenediamine-type, 1,3-bisaminomethylcyclohexane-type, and isocyanurate-type. In particular, aminophenol-type and diaminodiphenylmethane-type glycidylamine-type epoxy resins are particularly preferred due to their well-balanced physical properties.

[0022] Commercially available aminophenol-type epoxy resins include ELM120 and ELM100 (both manufactured by Sumitomo Chemical Co., Ltd.), jER (registered trademark) 630 (manufactured by Mitsubishi Chemical Corporation), Araldite (registered trademark) MY0510 (manufactured by Huntsman Corporation), Araldite (registered trademark) MY0600 (manufactured by Huntsman Advanced Materials), Araldite (registered trademark) MY0610 (manufactured by Huntsman Advanced Materials), and Araldite (registered trademark) MY721 (manufactured by Huntsman Advanced Materials).

[0023] Commercially available diaminodiphenylmethane epoxy resins include ELM100 and ELM434 (both manufactured by Sumitomo Chemical Co., Ltd.).

[0024] Among the epoxy resins used as non-trifunctional epoxy resins, glycidyl ether epoxy resins with phenol as a precursor are preferably used as bifunctional epoxy resins. Examples of such epoxy resins include bisphenol A epoxy resins, bisphenol F epoxy resins, bisphenol S epoxy resins, naphthalene epoxy resins, biphenyl epoxy resins, urethane-modified epoxy resins, hydantoin and resorcinol epoxy resins, and glycidyl aniline epoxy resins.

[0025] Commercially available bisphenol A epoxy resins include EPON® 825 (manufactured by Mitsubishi Chemical Corporation), Epicron® 850 (manufactured by DIC Corporation), Epototo® YD-128 (manufactured by Nippon Steel Chemical Co., Ltd.), and DER-331 and DER-332 (both manufactured by The Dow Chemical Company). Examples of bisphenol F epoxy resins include GY285 (bisphenol F, manufactured by Huntsman Advanced Materials). Commercially available glycidyl aniline epoxy resins include GAN and GOT (manufactured by Nippon Kayaku Co., Ltd.), and PxGAN (diglycidyl-p-phenoxyaniline, manufactured by Toray Fine Chemicals Co., Ltd.).

[0026] The epoxy resin composition for FRP of the present invention may be used with a curing agent. The curing agent described here is a compound containing an active group capable of reacting with epoxy groups, and is a curing agent for the epoxy resin contained in the epoxy resin composition of the present invention. Specific examples of the curing agent include dicyandiamide, aromatic polyamines, aminobenzoic acid esters, various acid anhydrides, phenol novolac resins, cresol novolac resins, polyphenol compounds, imidazole derivatives, aliphatic amines, tetramethylguanidine, thiourea adduct amines, carboxylic acid anhydrides such as methylhexahydrophthalic anhydride, carboxylic acid hydrazides, carboxylic acid amides, polymercaptans, and Lewis acid complexes such as boron trifluoride ethylamine complex.

[0027] By using an aromatic polyamine as a curing agent, it is possible to obtain a cured epoxy resin product with good heat resistance. In particular, among aromatic polyamines, various isomers of diaminodiphenyl sulfone are the most suitable curing agents for obtaining a cured epoxy resin product with good heat resistance.

[0028] Furthermore, by combining dicyandiamide with a urea compound, such as 3,4-dichlorophenyl-1,1-dimethylurea, or by using imidazoles as a curing agent, high heat and water resistance can be achieved while curing at relatively low temperatures. Curing epoxy resins with acid anhydrides produces cured products with lower water absorption than those produced by amine compound curing. Furthermore, by using latent, e.g., microencapsulated, versions of these curing agents, the storage stability of prepregs, particularly their tackiness and drapeability, remains stable even when left at room temperature.

[0029] These curing agents may be used alone or in combination.

[0030] Commercially available aromatic polyamine curing agents include "Seikacure (registered trademark)" S (manufactured by Wakayama Seika Kogyo Co., Ltd.), MDA-220 (manufactured by Mitsui Fine Chemicals, Inc.), "jER Cure (registered trademark)" W (manufactured by Mitsubishi Chemical Corporation), and 3,3'-DAS (manufactured by Mitsui Fine Chemicals, Inc.), "Lonzacure (registered trademark)" M-DEA (manufactured by Lonza Corporation), "Lonzacure (registered trademark)" M-DIPA (manufactured by Lonza Corporation), "Lonzacure (registered trademark)" M-MIPA (manufactured by Lonza Corporation), and "Lonzacure (registered trademark)" DETDA 80 (manufactured by Lonza Corporation). (polymer particles) In the present invention, the resin layer contains polymer particles, which improves the toughness of the matrix resin and interlaminar toughness when used in an FRP laminate. The use of polymer particles results in stress concentration in the resin surrounding the particles when a crack propagates through the resin layer. This causes the crack to propagate toward the polymer particle, increasing the energy required for fracture, thereby providing high interlaminar toughness. The polymer particles used in the present invention are preferably made from polymer resins that can be mixed or dissolved in the matrix resin. Among these, polyamides are most preferred. Among polyamides, nylon 6, nylon 11, nylon 12, and copolymers of nylon 6 and 12 provide particularly good adhesive strength with thermosetting resins. The shape of these polymer particles can be spherical, non-spherical, or porous. However, spherical particles are preferred because they do not reduce the flow properties of the resin, provide excellent viscoelasticity, eliminate stress concentration points, and provide high interlaminar toughness.

[0031] The average particle size of the polymer particles is preferably in the range of 5 to 50 μm, more preferably in the range of 7 to 40 μm, and even more preferably in the range of 10 to 30 μm. The range may be a combination of any of the upper and lower limits above. By setting the average particle size to 5 μm or more, the polymer particles do not penetrate into the reinforcing fiber bundles and remain in the resin layer of the resulting laminate. By setting the average particle size to 50 μm or less, the thickness of the resin layer on the prepreg surface can be optimized, and the fiber mass content in the resulting laminate can be optimized.

[0032] Here, the average particle size of polymer particles is determined by taking a photograph of the particles at 1000x magnification or more using a microscope such as a scanning electron microscope, randomly selecting a particle, determining the diameter of the circle circumscribing the particle as the particle size, and calculating the average particle size (n=50).

[0033] Commercially available polymer particles include Amilan (registered trademark) SP-500, SP-10, TR-1, and TR-2 (manufactured by Toray Industries, Inc.), and Orgasol (registered trademark) 1002D, 2001UD, 2001EXD, 2002D, 3202D, 3501D, and 3502D (all manufactured by Arkema). Furthermore, examples of polymer particles made of polyamide include the polyamide particles described in International Publication No. 2018 / 207728 (explained in the Examples). (Resin-rich and fiber-rich areas) In the laminate of the present invention, a resin layer exists between the reinforcing fibers in the unidirectional reinforcing fiber layer and the reinforcing fiber woven fabric of the reinforcing fiber woven fabric layer adjacent to the surface thereof, but since resin pools occur in the region where the warp and weft yarns of the woven FRP intersect, the interlayer thickness of the resin layer is non-uniform in the in-plane direction, and the resin layer has resin-rich parts mainly caused by resin pools and fiber-rich parts with a low resin content due to the narrow distance between the yarns constituting the fabric and the unidirectional reinforcing fibers. Specifically, the definitions of the resin-rich part and the fiber-rich part are as follows. The G described later in "(4) Measurement of Mode II Interlaminar Toughness (GIIC)" in the Examples IIC The test piece was cut in a direction inclined at 22.5 degrees to the direction perpendicular to the fiber direction of the unidirectional reinforcing fiber, and the cross section was polished and then magnified 200 times with an optical microscope so that the resin layer between the unidirectional reinforcing fiber and the reinforcing fiber fabric was within the field of view. IICThe entire width of the test piece is photographed. In the resin layer of the photographed image, the distance between the center point in the out-of-plane direction of the single unidirectional reinforcing fiber closest to the resin layer on any line parallel to the out-of-plane direction and the center point in the out-of-plane direction of the single fiber composing the reinforcing fiber fabric closest to the resin layer is taken as the interlayer thickness at any coordinate. This operation is performed every 10 μm across the entire width of the resin layer in the in-plane direction of the reinforcing fibers to obtain each interlayer thickness. Among the obtained interlayer thicknesses, the resin-rich region is defined as the area from the coordinate of the thickest interlayer thickness to the resin layer 50 μm away on both sides in the in-plane direction, and the fiber-rich region is defined as the area from the coordinate of the thinnest interlayer thickness to the resin layer 50 μm away on both sides in the in-plane direction. Note that if the resin-rich region and the fiber-rich region overlap, they are not considered to be either region; the regions excluding the overlapping region are defined as the resin-rich region and the fiber-rich region, respectively.

[0034] In the resin-rich portion of the captured image, the ratio of the area occupied by polymer particles to the area of ​​the entire resin-rich portion is measured as the particle ratio in the resin-rich portion. The ratio of the area occupied by polymer particles to the area of ​​the entire fiber-rich portion is measured as the particle ratio in the fiber-rich portion. Five laminate samples are prepared, and in each sample, a resin-rich portion and a fiber-rich portion are designated. The particle ratios in the resin-rich portion and the fiber-rich portion are measured, and the average values ​​of the five samples are defined as the particle ratio in the resin-rich portion and the particle ratio in the fiber-rich portion, respectively.

[0035] In the FRP laminate of the present invention, in order to achieve both high interlaminar toughness and a low fiber crimp angle, it is preferable to make the particle ratio of the fiber-rich portion higher than the particle ratio of the resin-rich portion.

[0036] By reducing the particle ratio in the resin-rich portion, it is easy to reduce the interlaminar thickness of the resin layer between the reinforcing fiber fabric and the unidirectional reinforcing fibers, and therefore the crimp angle of the reinforcing fiber fabric can be reduced. In order to reduce the crimp angle of the reinforcing fiber fabric, the particle ratio in the resin-rich portion is preferably 45% or less, and more preferably 30% or less. In addition, if the particle ratio in the resin-rich portion is too low, the mode II interlaminar toughness (G IIC ) becomes low, so the particle ratio of the resin-rich portion is preferably 5% or more.

[0037] High interlaminar toughness can be obtained by increasing the particle ratio of the resin-rich portion. To increase interlaminar toughness, the particle ratio of the fiber-rich portion is preferably 50% or more. Furthermore, if the particle ratio of the fiber-rich portion is too high, the shear modulus during water absorption between layers decreases, so the particle ratio of the fiber-rich portion is preferably 80% or less.

[0038] Furthermore, in order to achieve high interlaminar toughness while reducing the crimp angle of the reinforcing fiber fabric, the particle ratio of the fiber-rich portion is preferably at least 15% higher than the particle ratio of the resin-rich portion, more preferably at least 20% higher. On the other hand, the particle ratio of the fiber-rich portion relative to the particle ratio of the resin-rich portion is preferably less than 60%. [Example]

[0039] The laminate of the present invention will be described in more detail below using examples. The resin raw materials, prepregs, and FRP laminates used in the examples are prepared and evaluated as follows. The preparation and evaluation of the prepregs in the examples was carried out in an atmosphere of a temperature of 25°C ± 2°C and a relative humidity of 50%, unless otherwise specified. <Carbon fiber (for unidirectional reinforcement)> "TORAYCA (registered trademark)" T800S-24K (carbon fiber with 24,000 filaments, tensile strength of 7.0 GPa, tensile modulus of elasticity of 324 GPa, and tensile elongation of 2.0%, manufactured by Toray Industries, Inc.). <Carbon fiber (for reinforced fiber fabrics)> "TORAYCA (registered trademark)" cloth "CM6644G" (manufactured by Toray Industries, Inc.). <Matrix resin> Epoxy resin with three or more functionalities Araldite® MY0510 (triglycidyl para-aminophenol, manufactured by Huntsman Advanced Materials) ELM434 (tetraglycidyldiaminodiphenylmethane, manufactured by Sumitomo Chemical Co., Ltd.) Difunctional epoxy resin PxGAN (diglycidyl-p-phenoxyaniline, manufactured by Toray Fine Chemicals Co., Ltd.) "EPON (registered trademark)" 825 (bisphenol A epoxy resin, manufactured by Mitsubishi Chemical Corporation) <Curing agent> "Seikacure (registered trademark)"-S (4,4'-diaminodiphenyl sulfone, manufactured by Wakayama Seika Co., Ltd.) 3,3'-DAS (Mitsui Fine Chemicals, Inc.) <Thermoplastic resin> "Sumikaexcel (registered trademark)" PES5003P (polyethersulfone, manufactured by Sumitomo Chemical Co., Ltd.). <Polymer particles> Polymer particles: Polyamide 6 particles (mode diameter: 15.0 μm) obtained by the following method With reference to WO 2018 / 207728, 200 g of ε-caprolactam (manufactured by Toray Industries, Inc.), 800 g of polyethylene glycol (Wako Pure Chemical Industries, Ltd., grade 1 polyethylene glycol 20,000, weight average molecular weight 18,600) as the second component polymer, and 1,000 g of water were added to a 3 L autoclave equipped with a helical ribbon stirring blade to form a homogeneous solution, which was then sealed and purged with nitrogen. The stirring speed was then set to 100 rpm, and the temperature was raised to 240°C. During this time, the system pressure was kept at 10 kg / cm. 2 After reaching 10 kg / cm 2 After the temperature reached 240°C, the steam pressure was reduced to 0.2 kg / cm. 2The pressure was released at a rate of 1 / min. The temperature was then maintained for 1 hour while nitrogen was flowing to complete the polymerization, and the mixture was then discharged into a 2,000g water bath to obtain a slurry. After dissolving the dissolved material, it was filtered, and 2,000g of water was added to the filter cake and washed at 80°C. The slurry was then passed through a 200µm sieve to remove any agglomerates. The isolated material was then filtered again and dried at 80°C for 12 hours to produce 140g of polyamide 6 powder. The melting point of the resulting powder was 218°C, the same as polyamide 6, and the crystallization temperature was 170°C. (1) Preparation of epoxy resin composition The epoxy resin and thermoplastic resin were kneaded in the ratios shown in Table 1, heated to 150°C or higher, and stirred for 1 hour to dissolve the thermoplastic resin, yielding a transparent viscous liquid. After lowering the temperature of this liquid while kneading, a curing agent shown in Table 1 was added and further kneaded to obtain a first resin composition ("1" in Table 1).

[0040] The epoxy resin and thermoplastic resin were mixed in the proportions shown in Table 1, heated to 150°C or higher, and stirred for 1 hour to dissolve the thermoplastic resin, yielding a transparent viscous liquid. After the temperature of this liquid was lowered while mixing, the polymer particles shown in Table 1 were added and mixed, and then a curing agent was added and mixed to obtain a second resin composition ("2" in Table 1). (2) Manufacturing of unidirectional prepreg The two-stage impregnation method was used. Several silicone-coated release papers were prepared, and the first resin composition or the second resin composition prepared in (1) above was uniformly coated on the papers to form the first resin film (resin basis weight 30 g / m). 2 ) or second resin film (resin basis weight 20g / m 2 ) Carbon fibers uniformly aligned in one direction were sandwiched between two first resin films, and heated and pressed using a press roll to obtain a primary prepreg in which the carbon fibers were impregnated with the first resin composition. Next, both release papers were peeled off from the primary prepreg. Next, the primary prepreg was sandwiched between second resin films, and heated and pressed using a press roll to obtain a unidirectional prepreg in which the primary prepreg was impregnated with the second resin composition (carbon fiber mass 190 g / m 2, resin content 35.5% by mass). (3) Manufacturing of woven prepregs The two-stage impregnation method was used to produce the prepreg. Several pieces of silicone-coated release paper were prepared, and the first resin composition or the second resin composition prepared in (1) above was uniformly coated onto the paper to produce the first resin film or the second resin film, respectively. A carbon fiber fabric was sandwiched between two first resin films, and heated and pressed using a press roll to obtain a primary prepreg in which the carbon fibers were impregnated with the first resin composition. Next, both release papers were peeled off from the primary prepreg. Next, the primary prepreg was sandwiched between two second resin films, and heated and pressed using a press roll to obtain a woven fabric prepreg in which the primary prepreg was impregnated with the second resin composition (carbon fiber mass 195 g / m 2 , resin content 40% by mass). (4) Mode II interlaminar toughness (G IIC ) measurement By performing the following operations (a) to (d), IIC was measured. (a) Unidirectional prepreg and woven fabric prepreg were cut into 250 mm x 250 mm pieces, and the fiber orientation of the unidirectional prepreg was aligned in the same direction to create two unidirectional prepreg laminates, each consisting of 13 plies. Two 13-ply unidirectional prepregs were sandwiched between two 13-ply unidirectional prepregs, with one ply of woven fabric prepreg at the center, to create a 27-ply prepreg laminate consisting of unidirectional prepreg and woven fabric prepreg. The warp yarns of the woven fabric prepreg were aligned with the fiber orientation of the unidirectional prepreg. A rectangular 12.5 μm-thick fluororesin film was inserted 40 mm from the edge of the laminate in the 0° direction between the unidirectional prepreg and one of the woven fabric prepregs (between the 13th and 14th plies) to create an initial crack. (b) The laminated prepreg was tightly covered with nylon film and heated to 180°C at a rate of 1.5°C / min in an autoclave. After that, it was heated at 180°C and a pressure of 7 kg / cm. 2 The mixture was heated and pressed for 2 hours at room temperature to harden the mixture, thereby forming an FRP laminate. (c) The unidirectional material of the FRP laminate obtained in (b) was cut into a 20 mm wide and 195 mm long piece with the 0° angle as the length direction. The fiber direction was cut parallel to the length direction of the sample to prepare a test piece. (d) The test piece was subjected to an ENF test in accordance with JIS K7086 (1993) Appendix 2. Five test pieces were measured. (5) Measurement of interlayer thickness between resin-rich and fiber-rich areas The particle ratio measurement of the resin-rich and fiber-rich parts was carried out using the (4) Mode II interlaminar toughness (G IIC ) The test specimen was cut at an arbitrary point in the non-film-inserted portion in a direction tilted 22.5 degrees relative to the direction perpendicular to the fiber direction of the unidirectional reinforcing fibers, and the cross section was polished and then photographed under an optical microscope at 200x magnification so that the resin layer between the unidirectional reinforcing fibers and the reinforcing fiber fabric was within the field of view. In order to measure the entire width of the resin layer in the test specimen, photographs were taken multiple times to obtain images, and these images were used for measurement.

[0041] In the resin layer of the photographed image, the distance between the center point of the unidirectional reinforcing fiber closest to the resin layer in the out-of-plane direction on an arbitrary line parallel to the out-of-plane direction and the center point of the fiber closest to the resin layer in the out-of-plane direction among the fibers constituting the reinforced fiber woven fabric was taken as the interlayer thickness at arbitrary coordinates. This operation was performed every 10 μm across the entire width of the resin layer in the in-plane direction of the reinforcing fibers, and each interlayer thickness was obtained. Among the obtained interlayer thicknesses, the region from the coordinate of the thickest interlayer thickness to a distance of 50 μm on both sides in the in-plane direction was taken as the resin-rich region, and the region from the coordinate of the thinnest interlayer thickness to a distance of 50 μm on both sides in the in-plane direction was taken as the fiber-rich region. The average values ​​of the resin-rich region and fiber-rich region measured from the cross-sectional images of five samples were taken as the interlayer thicknesses of the resin-rich region and fiber-rich region, respectively. (6) Measurement of particle ratio between resin-rich and fiber-rich parts In the resin-rich portion of the image taken in (5), the ratio of the area occupied by polymer particles to the area of ​​the entire resin-rich portion was measured as the particle ratio in the resin-rich portion. Also, the ratio of the area occupied by polymer particles to the area of ​​the entire fiber-rich portion was measured as the particle ratio in the fiber-rich portion. (7) Crimp angle of reinforced fiber fabric The crimp angle of the reinforced fiber fabric is related to (4) Mode II interlaminar toughness (G IIC The test specimen was cut at any point in the non-film-inserted area in a direction perpendicular to the fiber direction of the unidirectional reinforcing fibers, and the cross section was polished and then photographed under an optical microscope at 200x magnification so that the reinforcing fiber fabric and the outermost surface of the specimen were within the field of view. In order to measure the entire width of the resin layer, photographs were taken multiple times to obtain images, and these images were used for the measurement.

[0042] In the captured image, a straight line parallel to the outermost surface of the test piece was used as the reference line. Furthermore, the center positions of the fiber bundles of the reinforcing fiber fabric in the out-of-plane direction of the FRP laminate were obtained at each coordinate in the in-plane direction, and a curve of the center line of the fiber bundles connecting these centers was obtained. The maximum and minimum points of the obtained curve were obtained, and a line A passing through any maximum point and the adjacent minimum points on both sides was obtained. The acute angle formed by the reference line and line A was taken as the crimp angle of the reinforcing fiber fabric. The same operation was performed for all maximum and minimum points in the captured image to obtain the crimp angle (two crimp angles were obtained for one maximum point). The average value of all crimp angles measured from the cross-sectional images of the five samples was taken as the crimp angle of the reinforcing fiber fabric. Example 1 ~3 , Comparative Example 1 ) Unidirectional prepregs and woven prepregs were prepared as described in (2) or (3) above using the compositions listed in Table 1, and prepreg laminates were constructed as described in (4)(a). Test specimens for the above-mentioned (4) Mode II Interlaminar Toughness (GIIC) test were prepared and GIIC measurements were carried out. The interlaminar thickness and particle fraction of the resin-rich region, the interlaminar thickness and particle fraction of the fiber-rich region, and the crimp angle of the reinforcing fiber woven fabric were also measured. The GIIC, interlaminar thickness and particle fraction of the resin-rich region, the interlaminar thickness and particle fraction of the fiber-rich region, and the crimp angle of the reinforcing fiber woven fabric are shown in Table 1.

[0043] [Table 1]

[0044] By comparing Example 1 with Comparative Example 1, it was shown that by increasing the particle ratio in the fiber-rich portion compared to the particle ratio in the resin-rich portion, high interlayer toughness was achieved while the crimp angle of the reinforcing fiber fabric was reduced.

[0045] Comparing Example 1 and Example 2, it was shown that by increasing the particle ratio in the fiber-rich portion by 20% or more compared to the particle ratio in the resin-rich portion, high interlayer toughness can be achieved while the crimp angle of the reinforcing fiber fabric can be reduced.

[0046] A comparison between Example 1 and Example 3 showed that the interlaminar toughness was improved by including a tri- or higher functional glycidylamine type epoxy resin in the matrix resin of the laminate. [Industrial Applicability]

[0047] According to the present invention, the high interlaminar toughness and small crimp angle of the reinforcing fiber fabric make it suitable for use in structures that undergo drilling. For example, in aerospace applications, it is suitable for use in aircraft primary structural materials such as main wings, tails, and floor beams, secondary structural materials such as flaps, ailerons, cowls, fairings, and interior materials, rocket motor cases, and artificial satellite structural materials, etc. Furthermore, in general industrial applications, it is suitable for use in structural materials for moving bodies such as automobiles, ships, and railway vehicles, drive shafts, etc.

Claims

1. a layer of a fiber-reinforced composite material (hereinafter referred to as a unidirectional reinforcing fiber layer) containing reinforcing fibers aligned in one direction and a matrix resin; A laminate including a layer of a fiber-reinforced composite material (hereinafter referred to as a reinforcing fiber fabric layer) containing a reinforcing fiber fabric and a matrix resin, laminated adjacent to the surface of the layer, a resin layer is present between the unidirectional reinforcing fibers in at least one unidirectional reinforcing fiber layer and the reinforcing fiber woven fabric in at least one reinforcing fiber woven fabric layer adjacent to the surface of the unidirectional reinforcing fiber layer; the resin layer contains polymer particles, and has a resin-rich portion and a fiber-rich portion formed therein; The laminate has a higher particle ratio of the polymer particles in the fiber-rich portion than in the resin-rich portion.

2. 2. The laminate according to claim 1, wherein the particle ratio in the fiber-rich portion is at least 20% higher than the particle ratio in the resin-rich portion.

3. 3. The laminate according to claim 1, wherein the matrix resin contains a tri- or higher functional glycidyl amine type epoxy resin.

4. 4. The laminate according to claim 1, wherein the polymer particles account for 45% or less of the particle ratio in the resin-rich portion.

5. 5. The laminate according to claim 1, wherein the particle ratio of the polymer particles in the fiber-rich portion is 50% or more.

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