Fiber-reinforced plastic and method for manufacturing the same

Abstract

The present invention relates to a fiber-reinforced plastic comprising: a reinforcing fiber group, a thermosetting resin layer, and a thermoplastic resin layer containing a first thermoplastic resin, wherein a surface layer of the aforementioned fiber-reinforced plastic has the aforementioned thermoplastic resin layer, an interface of the aforementioned thermoplastic resin layer and the aforementioned thermosetting resin layer is located inside the aforementioned reinforcing fiber group, and the aforementioned thermosetting resin layer has an island-in-sea structure in which island phases of a second thermoplastic resin or a rubbery polymer are dispersed in a sea phase of a thermosetting resin.

Description

Technical Field

[0001] This invention relates to fiber-reinforced plastics and methods for manufacturing the same. Background Technology

[0002] Fiber-reinforced plastics, which use thermosetting resins as the matrix resin and combine them with reinforcing fibers such as carbon fiber and glass fiber, are lightweight and have excellent mechanical properties such as strength and rigidity, as well as heat resistance and corrosion resistance. Therefore, they are used in many fields such as aerospace, automobiles, railway vehicles, ships, civil engineering and sports equipment.

[0003] However, the aforementioned fiber-reinforced plastics are not suitable for manufacturing components or molded bodies with complex shapes using a single molding process. In the aforementioned applications, it is necessary to prepare components formed from fiber-reinforced plastics and then join or bond them with other components to achieve integration.

[0004] For example, as a method to integrate fiber-reinforced plastics with components of the same or different types, mechanical joining methods such as bolts, rivets, and screws, as well as joining methods involving adhesives, can be used. Mechanical joining methods suffer from the problem of reduced strength around the holes due to the creation of openings in the fiber-reinforced plastic and other components. When adhesives are involved, there is a problem of poor bonding or adhesion at the boundary between the fiber-reinforced plastic molded body and other components due to peeling or other defects. Furthermore, the above-mentioned joining methods require pre-processing of the joining parts, such as opening processes and adhesive coating processes, which reduces processability.

[0005] Therefore, as a method to join fiber-reinforced plastics to other components without creating holes in the fiber-reinforced plastics or without using adhesives, fiber-reinforced plastics with thermoplastic resins on their surfaces have been proposed.

[0006] Patent Document 1 discloses a laminate formed by integrally integrating a thermoplastic resin layer disposed on a surface with a thermosetting resin layer, which is a matrix resin of a fiber-reinforced plastic, and the laminate itself. By integrally integrating the thermoplastic resin layer and the thermosetting resin layer with an uneven shape, they are firmly bonded together. Furthermore, by disposing the thermoplastic resin layer on the surface, it is possible to melt the thermoplastic resin layer to achieve bonding of other adherends to the fiber-reinforced plastic.

[0007] Patent Document 2 discloses a laminate having an adhesive resin layer comprising a thermosetting resin and a thermoplastic resin existing in the form of a continuous phase between an adherend layer and a thermosetting resin layer which is a matrix resin of a fiber-reinforced plastic, and a method for manufacturing the same. The thermoplastic resin existing in the form of a continuous phase in the adhesive resin layer acts as an anchor, firmly bonding the thermoplastic resin and the thermosetting resin in the adhesive resin layer. Furthermore, it is believed that by melting the thermoplastic resin contained in the adhesive resin layer, the bonding strength between the adherend and the fiber-reinforced plastic can be improved.

[0008] Existing technical documents

[0009] Patent documents

[0010] Patent Document 1: International Publication No. 2004 / 060658

[0011] Patent Document 2: Japanese Patent Application Publication No. 2006-198784 Summary of the Invention

[0012] The problem that the invention aims to solve

[0013] The laminates in Patent Documents 1 and 2 do not require openings or adhesives, effectively utilizing the strength and rigidity of fiber-reinforced plastics. The bonding process is simple, resulting in high processability. However, to expand the application range of these products, it is necessary not only to further improve the bonding strength with the adherends but also to enhance the reliability of the bonding structure. In Patent Document 1, although the composite structure of reinforcing fibers and thermoplastic resin exhibits high toughness, stress concentration in the less tough thermosetting resin can sometimes lead to cracking. In Patent Document 2, the less tough thermosetting resin contains thermoplastic resin as a continuous phase; however, stress concentration at the interface between the two resins can sometimes lead to delamination.

[0014] The objective of this invention is to provide fiber-reinforced plastics that not only bond with other adherends with excellent bonding strength, but also achieve highly reliable bonded structures.

[0015] Methods for solving problems

[0016] The inventors of this application conducted repeated and careful research, and as a result found a solution to the above-mentioned problems, thus completing this invention. That is, the invention is as follows.

[0017] [1] A fiber-reinforced plastic comprising: a group of reinforcing fibers, a thermosetting resin layer, and a thermoplastic resin layer containing a first thermoplastic resin.

[0018] The aforementioned fiber-reinforced plastic has a surface layer containing the aforementioned thermoplastic resin layer.

[0019] The interface between the aforementioned thermoplastic resin layer and the aforementioned thermosetting resin layer is located inside the aforementioned reinforcing fiber assembly.

[0020] The aforementioned thermosetting resin layer has an island structure in which an island phase, mainly composed of a second thermoplastic resin or rubber polymer, is dispersed in a marine phase, mainly composed of a thermosetting resin.

[0021] [2] As in [1] the aforementioned fiber-reinforced plastic, wherein the aforementioned second thermoplastic resin is a resin of the same kind as the aforementioned first thermoplastic resin.

[0022] [3] As in [2] the aforementioned fiber-reinforced plastic, wherein the aforementioned second thermoplastic resin is the same as the aforementioned first thermoplastic resin.

[0023] [4] The fiber-reinforced plastic as described in [1] or [2], wherein the melting point of the second thermoplastic resin and the rubber polymer is higher than the melting point of the first thermoplastic resin.

[0024] [5] The fiber-reinforced plastic as described in any one of [1] to [4], wherein the aforementioned island phase comprises the components of the aforementioned marine phase thermosetting resin.

[0025] [6] The fiber-reinforced plastic as described in any of [1] to [5], wherein the aforementioned island phase is located near the interface between the aforementioned thermosetting resin layer and the aforementioned thermoplastic resin layer.

[0026] [7] The fiber-reinforced plastic as described in any one of [1] to [6], wherein,

[0027] Within a thickness direction of 100 μm in the cross section from the outermost fiber toward the aforementioned thermosetting resin layer, the volume percentage of the aforementioned island phase is 1% or more relative to the aforementioned range of 100% by volume.

[0028] [8] The fiber-reinforced plastic as described in any one of [1] to [7], wherein the average particle size of the aforementioned island phase in the thickness direction section is 0.1 μm or more and 10 μm or less.

[0029] [9] The fiber-reinforced plastic as described in any one of [1] to [8], wherein the length of the major axis of the aforementioned island phase is more than 3 μm and less than 30 μm.

[0030]

[10] The fiber-reinforced plastic of any one of [1] to [9], wherein the elastic modulus of the island phase is lower than that of the marine phase.

[0031]

[11] The fiber-reinforced plastic of any one of [1] to

[10] , wherein the glass transition temperature of the island phase is lower than that of the marine phase.

[0032]

[12] The fiber-reinforced plastics mentioned in any of [1] to

[11] have a surface free energy of 10 to 50 mJ / m as determined by the Wilhelmy method. 2 The reinforcing fiber is used as the aforementioned reinforcing fiber.

[0033]

[13] A method for manufacturing fiber-reinforced plastic, which is any one of the aforementioned methods for manufacturing fiber-reinforced plastic in [1] to

[12] , wherein the aforementioned manufacturing method includes:

[0034] The process of impregnating the precursor of the aforementioned island phase and the precursor of the aforementioned thermosetting resin layer on both sides of the reinforcing fiber sheet constituting the aforementioned reinforcing fiber group to form the aforementioned island phase and the aforementioned thermosetting resin layer.

[0035] The process of softening or melting the precursor of the aforementioned island phase and the precursor of the aforementioned thermoplastic resin layer and disposing them on at least one side of the aforementioned reinforcing fiber sheet on which the aforementioned island phase and the aforementioned thermosetting resin layer are formed, thereby forming the aforementioned island phase and the aforementioned thermoplastic resin layer to produce an intermediate; and

[0036] The process of shaping the obtained intermediate.

[0037]

[14] A method for manufacturing fiber-reinforced plastic, which is any one of the aforementioned methods for manufacturing fiber-reinforced plastic in [1] to

[12] , comprising:

[0038] The process of impregnating the aforementioned island phase precursor and the aforementioned thermosetting resin layer precursor onto both sides of the reinforcing fiber sheet constituting the aforementioned reinforcing fiber group to form the aforementioned island phase and the aforementioned thermosetting resin layer; and

[0039] The process of softening or melting the precursor of the aforementioned thermoplastic resin layer and disposing it on at least one side of the aforementioned reinforcing fiber sheet having the aforementioned island phase and the aforementioned thermosetting resin layer, thereby forming the aforementioned thermoplastic resin layer to produce an intermediate; and

[0040] The process of shaping the obtained intermediate.

[0041]

[15] A method for manufacturing fiber-reinforced plastic, which is any one of the aforementioned methods for manufacturing fiber-reinforced plastic in [1] to

[12] , wherein the aforementioned manufacturing method includes:

[0042] The process of impregnating both sides of the reinforcing fiber sheet constituting the aforementioned reinforcing fiber group with the precursor of the aforementioned thermosetting resin layer to form the aforementioned thermosetting resin layer.

[0043] The process of softening or melting the precursor of the aforementioned island phase and the precursor of the aforementioned thermoplastic resin layer and disposing them on at least one side of the aforementioned reinforcing fiber sheet on which the aforementioned thermosetting resin layer is formed, thereby forming the aforementioned island phase and the aforementioned thermoplastic resin layer to produce an intermediate; and

[0044] The process of shaping the obtained intermediate.

[0045]

[16] A method for manufacturing fiber-reinforced plastic, which is any one of the aforementioned methods for manufacturing fiber-reinforced plastic in [1] to

[12] , wherein the aforementioned method includes:

[0046] The process of impregnating one side of the reinforcing fiber sheet constituting the aforementioned reinforcing fiber group with the aforementioned thermoplastic resin layer precursor, forming the aforementioned thermoplastic resin layer, and then vibrating it to disperse the aforementioned thermoplastic resin layer precursor in the aforementioned reinforcing fiber sheet.

[0047] The process of impregnating the precursor of the aforementioned thermosetting resin layer onto another side of the aforementioned reinforcing fiber sheet to form an intermediate; and

[0048] The process of shaping the obtained intermediate.

[0049] Invention Effects

[0050] According to the present invention, it is possible to obtain fiber-reinforced plastics that can not only bond with other adherends with excellent bonding strength, but also achieve highly reliable bonded structures. Attached Figure Description

[0051] [ Figure 1 ] Figure 1 This is a schematic diagram illustrating one embodiment of the fiber-reinforced plastic of the present invention.

[0052] [ Figure 2 ] Figure 2 The schematic diagram showing a cross-section perpendicular to a plane of the fiber-reinforced plastic in this invention is a diagram that helps illustrate the determination of the volume ratio of island phases in the fiber-reinforced plastic. Detailed Implementation

[0053] The following is for reference only. Figure 1 The invention will be described in detail, but the accompanying drawings are provided for easy understanding of the invention and are not intended to limit the invention in any way.

[0054] <Fiber-reinforced plastics>

[0055] [Composition of fiber-reinforced plastics]

[0056] The fiber-reinforced plastic according to embodiments of the present invention comprises: a reinforcing fiber group, a thermosetting resin layer, and a thermoplastic resin layer containing a first thermoplastic resin.

[0057] The aforementioned fiber-reinforced plastic has a surface layer containing the aforementioned thermoplastic resin layer.

[0058] The interface between the aforementioned thermoplastic resin layer and the aforementioned thermosetting resin layer is located inside the aforementioned reinforcing fiber assembly.

[0059] The aforementioned thermosetting resin layer has an island structure in which an island phase, mainly composed of a second thermoplastic resin or rubber polymer, is dispersed in a marine phase, mainly composed of a thermosetting resin.

[0060] The fiber-reinforced plastics according to the embodiments of the present invention can form an integrally molded article with excellent bonding strength by thermoforming with high processability when joining fiber-reinforced plastics with the same or different types of components without opening holes in the fiber-reinforced plastics or without the use of adhesives.

[0061] For example, such as Figure 1 As shown, the fiber-reinforced plastic 5 according to the embodiments of the present invention includes: a reinforcing fiber group including reinforcing fibers 1, a thermosetting resin layer 3, and a thermoplastic resin layer 4, wherein the surface layer of the fiber-reinforced plastic is the thermoplastic resin layer 4, the interface 6 between the thermoplastic resin layer 4 and the thermosetting resin layer 3 is located inside the reinforcing fiber group, and the thermosetting resin layer 3 has an island structure in which island phase 7, mainly composed of thermoplastic resin or rubber polymer, is dispersed in sea phase 8, mainly composed of thermosetting resin.

[0062] The thermosetting resin layer 3 has an island structure in which an island phase 7, mainly composed of thermoplastic resin or rubber polymer, is dispersed in a sea phase 8, mainly composed of thermosetting resin. As a result, the toughness of the thermosetting resin layer 3 is improved. Therefore, not only is the bonding strength improved, but from the viewpoint of suppressing the generation and propagation of cracks, the reliability of the bonding structure can be obtained.

[0063] Furthermore, in embodiments of the present invention, the interface between the thermoplastic resin layer 4 and the thermosetting resin layer 3 must be located within the reinforcing fiber assembly. This ensures a strong bond between the thermosetting resin layer 3 and the thermoplastic resin layer 4, providing a reliable bonding structure from the viewpoint of suppressing peeling between the two layers. Moreover, from the viewpoint of more firmly bonding the thermosetting resin layer 3 and the thermoplastic resin layer 4, it is preferable that a portion of the reinforcing fiber assembly is chemically and / or physically bonded to both the thermosetting resin layer 3 and the thermoplastic resin layer 4 at the interface 6 between the thermosetting resin layer 3 and the thermoplastic resin layer 4.

[0064] In embodiments of the present invention, if the island phase 7 is located near the interface 6 between the thermosetting resin layer 3 and the thermoplastic resin layer 4, the toughness of the thermosetting resin near the thermoplastic resin layer where stress concentration occurs can be effectively improved without significantly impairing the properties of the thermosetting resin layer. From this point of view, it is preferred.

[0065] Specifically, the distance between interface 6 and island phase 7 is preferably less than 100 μm, more preferably less than 70 μm, and even more preferably less than 50 μm.

[0066] Here, the distance between the interface 6 of the thermosetting resin layer 3 and the thermoplastic resin layer 4 and the island phase 7 is the average value obtained by measuring the shortest distance between 10 points on the outer periphery of the cross-section of the interface 6 of the thermosetting resin layer 3 and the thermoplastic resin layer 4 and the randomly selected island phase 7. This shortest distance can be measured, for example, by using known methods such as observing a cross-section of the fiber-reinforced plastic orthogonal to the fiber direction. Examples include: measuring by cross-sectional images obtained using X-ray CT, measuring by elemental analysis distribution images using energy-dispersive X-ray spectrometer (EDS), or measuring by cross-sectional observation images using an optical microscope, scanning electron microscope (SEM), or transmission electron microscope (TEM).

[0067] The island phase, primarily composed of a second thermoplastic resin or rubber polymer, can exist in both the thermosetting resin layer and the thermoplastic resin layer; alternatively, it can exist only in the thermosetting resin layer. From the viewpoint of improving the bonding strength of fiber-reinforced plastics, the island phase, primarily composed of a second thermoplastic resin or rubber polymer, is preferably present in both the thermosetting resin layer and the thermoplastic resin layer near the interface between them. From a processability viewpoint, it is preferable that it exists only in the thermosetting resin layer.

[0068] From the viewpoint that it can be processed at the same process temperature, the second thermoplastic resin is preferably a resin of the same kind as the first thermoplastic resin, and more preferably the same thermoplastic resin.

[0069] In this invention, "same type" refers to the same main components except for additives. Furthermore, "same main components" means the same main framework, but also includes cases where the number of repeating units or end treatments differ. Examples of analytical methods for island phases and thermoplastic resin layers with thermoplastic resin as the main component or with rubber polymer as the main component include: methods using differential scanning calorimetry (DSC) to analyze the glass transition temperature; methods using energy dispersive X-ray spectrometry (EDS) to analyze elemental distribution images; and methods using nanoindentation to analyze the elastic modulus.

[0070] Alternatively, from the viewpoint of suppressing structural changes at process temperatures, it is also preferable that the second thermoplastic resin or rubber polymer has a higher melting point than the first thermoplastic resin. The melting point of the second thermoplastic resin and the rubber polymer is preferably higher than that of the first thermoplastic resin.

[0071] From the viewpoint of suppressing disordered arrangement of reinforcing fibers, the average particle size of the island phase is preferably 0.1 μm to 10 μm, more preferably 0.3 μm to 5 μm, and even more preferably 0.5 μm to 3 μm. In particular, when high color quality is required, it is desirable to have uniform arrangement of reinforcing fibers.

[0072] From the viewpoint of improving the toughness of thermosetting resins, the length of the long axis of the island phase, which is mainly composed of a second thermoplastic resin or a rubber polymer, is preferably 3 μm to 30 μm, more preferably 5 μm to 25 μm, and even more preferably 5 μm to 20 μm. The long axis of the island phase exists along the reinforcing fibers, thereby suppressing disordered arrangement of the reinforcing fibers, which is preferable.

[0073] The average particle size and the length of the major axis of the island phases can be confirmed, for example, by observing a cross-section of the fiber-reinforced plastic orthogonal to the fiber direction using an optical microscope. The average particle size can be calculated based on the diameter of a circle that roughly represents the shape of at least 20 randomly selected island phases, observed from a cross-section orthogonal to the reinforcing fibers. Furthermore, the length of the island phase can be determined by considering the maximum length of the island phase in the observed cross-section as the length of its major axis. It should be noted that the major axis of the island phase is calculated from the line segment that separates the two points furthest apart from the outer periphery of the island phase from the straight line passing through the interior of the island phase as confirmed by the cross-sectional observation image described above.

[0074] In the thickness direction section of the fiber-reinforced plastic, within a 100 μm range from the outermost fiber toward the thermosetting resin layer, the volume percentage of the island phase is 0.1 vol% or more relative to 100 vol% of this range. From the viewpoint of further improving the toughness of the thermosetting resin, 1 vol% or more is preferred, and 10 vol% or more is more preferred. Furthermore, as an upper limit, it is acceptable as long as it does not significantly impair the mechanical properties of the thermosetting resin; preferably 95 vol% or less, and more preferably 80 vol% or less.

[0075] Here, to help illustrate the determination of the island phase volume ratio, a schematic diagram of a cross-section perpendicular to the plane of the fiber-reinforced plastic is shown. Figure 2 In a cross-section of the fiber-reinforced plastic orthogonal to the fiber direction, the fiber closest to the surface 9 of the fiber-reinforced plastic is designated as the outermost fiber 10. The volume of the island phase 7 is calculated within a measurement range 12 of 100 μm in the thickness direction from the center of the outermost fiber 10 through a reference line 11 that is horizontal to the surface of the fiber-reinforced plastic towards the thermosetting resin layer 3.

[0076] [Interface between thermosetting resin layer and thermoplastic resin layer]

[0077] In fiber-reinforced plastics, the interface between the thermosetting resin layer and the thermoplastic resin layer is located inside the reinforcing fiber assembly.

[0078] From the viewpoint of further improving mechanical bonding strength, a concave-convex shape is preferred for the shape of this interface. Therefore, the integrally molded article formed by bonding the fiber-reinforced plastic with other structural components through a thermoplastic resin layer according to the embodiments of the present invention exhibits excellent bonding strength. There are no particular limitations on the means of confirming the concave-convex shape of the interface; it can be confirmed by observing a cross-section of the fiber-reinforced plastic orthogonal to the fiber direction.

[0079] Here, known methods can be used to confirm the unevenness or concavity of the interface. Examples include: confirmation using cross-sectional images obtained via X-ray CT; confirmation using elemental analysis distribution images obtained via energy-dispersive X-ray spectrophotometry (EDS); or confirmation using cross-sectional observation images obtained via optical microscopy, scanning electron microscopy (SEM), or transmission electron microscopy (TEM). During observation, thermosetting resin layers and / or thermoplastic resin layers may also be stained to adjust contrast.

[0080] In the fiber-reinforced plastics according to embodiments of the present invention, the impregnation rate of thermosetting resin and thermoplastic resin (hereinafter sometimes referred to collectively as resin) in the reinforcing fiber group is preferably 80% or more. This impregnation rate is more preferably 85% or more, and even more preferably 90% or more.

[0081] The impregnation rate here refers to the proportion of the reinforcing fibers that make up the fiber-reinforced plastic to which they are impregnated with resin. The impregnation rate can be determined by measuring the proportion of unimpregnated portions using a specific method. A higher impregnation rate means fewer voids in the fiber-reinforced plastic, and a high impregnation rate is preferred from the viewpoint of further improving surface appearance and mechanical properties.

[0082] As a method for determining impregnation rate, the following method can be used: In the cross section of the fiber-reinforced plastic orthogonal to the fiber direction, when the total area of ​​the fiber-reinforced plastic including the voids is set as A0 and the cross-sectional area of ​​the voids is set as A1, the impregnation rate can be calculated by the following formula (1).

[0083] Impregnation rate (%) = (A0-A1) × 100 / A0···(1)

[0084] The details of the elements constituting the fiber-reinforced plastic of the present invention will be described below.

[0085] [Thermosetting resin layer]

[0086] The thermosetting resin layer has an island structure formed by dispersing an island phase, mainly composed of a second thermoplastic resin or a rubber polymer, within a marine phase, mainly composed of a thermosetting resin. Furthermore, the interface between the thermoplastic resin layer and the aforementioned thermosetting resin layer is located within the aforementioned reinforcing fiber assembly.

[0087] Thermosetting resin layers can be formed using reinforcing fiber groups and thermosetting resins.

[0088] Details are provided separately for the reinforcing fiber group and the thermosetting resin composition.

[0089] (Reinforcing fiber group)

[0090] The reinforcing fiber bundle is an aggregate (fiber bundle) of reinforcing fibers, which can be either continuous or discontinuous fibers, and can be appropriately selected from unidirectional arrangement, layering, or fabric configuration. From the viewpoint of obtaining fiber-reinforced plastics that are lightweight and have a higher level of durability, continuous fibers or fabrics in which the reinforcing fibers are arranged in a unidirectional direction are preferred.

[0091] The fiber bundle can be composed of the same reinforcing fibers or different reinforcing fibers. The number of fibers constituting the reinforcing fiber bundle is not particularly limited, but can be exemplified as 300 to 60,000 fibers. From a productivity point of view, it is preferable to have 300 to 48,000 fibers, and more preferably 1,000 to 24,000 fibers.

[0092] There are no particular restrictions on the types of reinforcing fibers constituting the reinforcing fiber group. For example, carbon fiber, glass fiber, aramid fiber, alumina fiber, silicon carbide fiber, boron fiber, metal fiber, natural fiber, and mineral fiber can be used. One type of fiber or two or more types can be used in combination. From the viewpoint of high specific strength, specific stiffness, and lightweight effect, PAN (Polyacrylonitrile), pitch-based, and synthetic fiber carbon fibers are preferred. Furthermore, from the viewpoint of improving the economy of the obtained fiber-reinforced plastic, glass fiber is preferred, especially from the perspective of balancing mechanical properties and economy, a combination of carbon fiber and glass fiber is preferred. Moreover, from the viewpoint of improving the impact absorption and shapeability of the obtained fiber-reinforced plastic, aramid fiber is preferred, especially from the perspective of balancing mechanical properties and impact absorption, a combination of carbon fiber and aramid fiber is preferred. Additionally, from the viewpoint of improving the electrical conductivity of the obtained fiber-reinforced plastic, reinforcing fibers coated with metals such as nickel, copper, and ytterbium, and pitch-based carbon fibers can also be used.

[0093] From the viewpoint of improving mechanical properties, it is preferable that the reinforcing fibers constituting the reinforcing fiber group have undergone surface treatment with a sizing agent. Examples of sizing agents include multifunctional epoxy resins, urethane resins, acrylic polymers, polyols, polyethyleneimine, and ethylene oxide adducts of aliphatic alcohols. Specifically, examples include polyglycidyl ethers of aliphatic polyols such as glycerol triglycidyl ether, diglycerol polyglycidyl ether, polyglycerol polyglycidyl ether, sorbitol polyglycidyl ether, araitol polyglycidyl ether, trimethylolpropane triglycidyl ether, and pentaerythritol polyglycidyl ether, as well as polyacrylic acid, acrylic acid, and methyl methacrylate. The following are suitable materials: copolymers of acrylic acid, copolymers of acrylic acid and maleic acid, or mixtures of two or more of the above, polyvinyl alcohol, glycerol, diglycerol, polyglycerol, sorbitol, araitol, trimethylolpropane, pentaerythritol, polyethyleneimine containing a large number of amino groups in one molecule, polyoxyethylene oil ether, etc. Among the above, glycerol triglycidyl ether, diglycerol polyglycidyl ether, and polyglycerol polyglycidyl ether are preferred because they contain a large number of highly reactive epoxy groups in one molecule, and are highly water-soluble and easy to coat.

[0094] In addition, as reinforcing fibers, it is preferable to use fibers with a surface free energy of 10–50 mJ / m as measured by the Wilhelmy method. 2 The reinforcing fibers are controlled within this range. By improving the affinity with both the thermosetting and thermoplastic resin layers, the aggregation of the reinforcing fibers is suppressed, resulting in better dispersion within each layer. Consequently, resin flow within the layers is promoted, and the formation of a dispersed phase of thermoplastic resin in the thermosetting resin is facilitated. Furthermore, the reinforcing fibers exhibit high affinity with both the thermosetting and thermoplastic resin layers, demonstrating high bonding strength at the interface between the thermosetting and thermoplastic resins where the reinforcing fibers cross. The surface free energy of the reinforcing fibers is preferably 15–40 mJ / m. 2 More preferably 18–35 mJ / m 2 .

[0095] Methods for controlling the surface free energy of reinforcing fibers include surface oxidation treatment to adjust the amount of oxygen-containing functional groups such as carboxyl and hydroxyl groups, and methods involving the attachment of one or more compounds to the surface. When attaching multiple compounds to the surface, compounds with high and low surface free energy can be mixed. The method for calculating the surface free energy of reinforcing fibers is described below. The surface free energy can be calculated using the following method: the contact angles between the reinforcing fiber and three solvents (purified water, ethylene glycol, and tricresyl phosphate) are measured respectively, and then the surface free energy is calculated using the Owens approximation. The steps are shown below, but the measuring equipment and detailed methods are not necessarily limited to the following.

[0096] Using a DataPhysics DCAT11, firstly, a single fiber was taken from the reinforcing fiber bundle and cut into eight fibers of 12±2 mm in length. These fibers were then glued parallel to each other, spaced 2–3 mm apart, onto a dedicated retainer FH12 (a flat plate coated with adhesive). Next, the tips of the single fibers were trimmed and placed within the DCAT11 retainer. During the measurement, a cell containing each solvent was brought close to the lower ends of the eight single fibers at a speed of 0.2 mm / s, immersing them until 5 mm from the tip of each fiber. Then, the single fiber was lifted at a speed of 0.2 mm / s. This operation was repeated at least four times. The force F acting on the single fiber while immersed in the liquid was measured using an electronic balance. This value was used to calculate the contact angle θ using the following formula.

[0097] COSθ = (Force F (mN) on 8 single fibers) / (8 (number of single fibers) × circumference of single fiber (m) × surface tension of solvent (mJ / m)) 2 ))

[0098] It should be noted that the measurements were performed on individual fibers extracted from different locations within three reinforcing fiber bundles. That is, for a single reinforcing fiber bundle, the average contact angle of a total of 24 individual fibers was calculated.

[0099] Surface free energy γ of reinforcing fiber f With the polar component γ of surface free energy p f and the nonpolar component of surface free energy γ d f Calculate it in the form of the sum.

[0100] Regarding the polar component γ of surface free energy p f In this case, the surface tension composition and contact angle of each liquid are substituted into the Owens approximation (a formula consisting of the polar and non-polar components of the inherent surface tension of each solvent and the contact angle θ), and plotted on X and Y. The surface free energy is then obtained by taking the square of the slope 'a' when performing a linear approximation using the least squares method. The non-polar component γ of the surface free energy is... d f The surface free energy γ of the reinforcing fiber is obtained from the square of the intercept b. f It is the sum of the square of the slope a and the square of the intercept b.

[0101] Y = a·X + b

[0102] X = √(the polar component of the solvent's surface tension (mJ / m)) 2 )) / √(The nonpolar component of the solvent's surface tension (mJ / m 2 )

[0103] Y = (1 + Cosθ)·(polar component of the surface tension of the solvent (mJ / m)) 2 )) / 2√(Nonpolar component of solvent surface tension (mJ / m 2 )

[0104] The polar component γ of the surface free energy of reinforcing fibers p f =a 2

[0105] The nonpolar component γ of the surface free energy of the reinforcing fiber d f =b 2

[0106] Total surface free energy γ f =a 2 +b 2 .

[0107] The polar and non-polar components of the surface tension of each solvent are shown below.

[0108] Purified water

[0109] Surface tension 72.8 mJ / m 2 Polar component 51.0 mJ / m 2 Nonpolar component 21.8 (mJ / m 2 )

[0110] · Ethylene glycol

[0111] Surface tension 48.0 mJ / m 2 Polar component 19.0 mJ / m 2 Nonpolar component 29.0 (mJ / m 2 )

[0112] Trimethylbenzene Phosphate

[0113] Surface tension 40.9 mJ / m 2 Polar component 1.7 mJ / m 2 Nonpolar component 39.2 (mJ / m 2 ).

[0114] Furthermore, regarding the reinforcing fiber bundles, if the tensile strength of the fiber bundle, as determined by the resin impregnation test method according to JIS R7608 (2007), is 3.5 GPa or higher, then a plastic with excellent bonding strength in addition to tensile strength can be obtained. Therefore, it is preferable if the tensile strength of the fiber bundle is 4.0 GPa or higher, which is even more preferable. The bonding strength mentioned above refers to the tensile shear bond strength determined according to ISO 4587 (1995).

[0115] The mass content of reinforcing fibers constituting the reinforcing fiber group in the fiber-reinforced plastic is preferably 30-90% by mass, more preferably 35-85% by mass, and even more preferably 40-80% by mass. If the mass content of reinforcing fibers is within the preferred range, a fiber-reinforced plastic with superior specific strength and specific modulus of elasticity can be obtained.

[0116] Furthermore, from the viewpoint of balancing the mechanical properties of fiber-reinforced plastics with the weldability of the second component, the volume of reinforcing fibers contained in the thermosetting resin layer is preferably 50 to 99% of the total volume of reinforcing fibers contained in the fiber-reinforced plastic as a whole, more preferably 75 to 95%.

[0117] Methods for determining the amount of reinforcing fibers in a thermosetting resin layer can be exemplified by the following: using a subdivision analysis of an X-ray CT image of a small piece of fiber-reinforced plastic, the percentage (%) is calculated by dividing the volume of reinforcing fibers present in the thermosetting resin layer by the total volume of reinforcing fibers contained in the small piece; or, based on a cross-sectional photograph of the small piece obtained using an optical microscope, scanning electron microscope (SEM), or transmission electron microscope (TEM), the percentage (%) is calculated by dividing the area of ​​reinforcing fibers present in the thermosetting resin layer by the area of ​​reinforcing fibers contained in the small piece as a whole. During observation, the thermosetting resin layer and / or thermoplastic resin layer may also be stained to adjust contrast.

[0118] (Thermosetting resin composition)

[0119] Thermosetting resin compositions contain thermosetting resins and may further include additives, depending on the intended use of the fiber-reinforced plastic.

[0120] The type of thermosetting resin contained in the thermosetting resin composition is not particularly limited, and includes, for example, unsaturated polyester resin, vinyl ester resin, epoxy resin, phenolic resin, urea resin, melamine resin, polyimide resin, cyanate ester resin, bismaleimide resin, benzoxazine resin, or copolymers of the above resins, modified versions, and resins obtained by blending at least two of the above. To improve impact resistance, elastomers or rubber components can be added to the thermosetting resin. Epoxy resin is preferred due to its excellent mechanical properties, heat resistance, and adhesion to reinforcing fibers.

[0121] Examples of epoxy resin main agents include bisphenol-type epoxy resins such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol AD ​​type epoxy resin, and bisphenol S type epoxy resin; brominated epoxy resins such as tetrabromobisphenol A diglycidyl ether; epoxy resins with a biphenyl backbone; epoxy resins with a naphthalene backbone; epoxy resins with a dicyclopentadiene backbone; Novolac-type epoxy resins such as phenol Novolac type epoxy resin and cresol Novolac type epoxy resin; and N,N,O-triglycidyl m-aminophenol. Glycidyl amine type epoxy resins such as hydroglycerol-based p-aminophenol, N,N,O-triglycidyl-4-amino-3-methylphenol, N,N,N',N'-tetraglycidyl-4,4'-methylenediphenylamine, N,N,N',N'-tetraglycidyl-2,2'-diethyl-4,4'-methylenediphenylamine, N,N,N',N'-tetraglycidyl-m-phenylenediamine, N,N-diglycidyl-aniline, and N,N-diglycidyl-o-toluidine, resorcinol diglycidyl ether, and triglycidyl isocyanurate, etc.

[0122] Thermosetting resin compositions may also contain curing agents. Examples of curing agents include dicyandiamide, aromatic amine compounds, phenol Novolac resin, cresol Novolac resin, polyphenol compounds, imidazole derivatives, tetramethylguanidine, thiourea addition amine, carboxylic acid hydrazide, formamide, polythiols, etc.

[0123] Furthermore, the curing agent is preferably 0.8 to 1.2 equivalents of the number of reactive functional groups of the thermosetting resin.

[0124] In addition, depending on the application of the fiber-reinforced plastic, the thermosetting resin composition may also contain fillers such as mica, talc, kaolin, hydrotalcite, sericite, bentonite, calcium silicate, sepiolite, montmorillonite, wollastonite, silica, calcium carbonate, glass beads, glass sheets, glass microspheres, clay, molybdenum disulfide, titanium dioxide, zinc oxide, antimony oxide, calcium polyphosphate, graphite, barium sulfate, magnesium sulfate, zinc borate, calcium borate, aluminum borate whiskers, potassium titanate whiskers, and polymer compounds; conductive materials such as metal-based and metal oxide-based compounds; halogen-based flame retardants such as brominated resins; antimony-based flame retardants such as antimony trioxide and antimony pentaoxide; phosphorus-based flame retardants such as ammonium polyphosphate, aromatic phosphates, and red phosphorus; organic acid metal salt flame retardants such as organoborate metal salts, carboxylic acid metal salts, and aromatic sulfonylimide metal salts; zinc borate, zinc, and oxygen. Inorganic flame retardants such as zinc oxide and zirconium compounds; nitrogen-based flame retardants such as cyanuric acid, isocyanuric acid, melamine, melamine cyanurate, melamine phosphate, and guanidine nitride; fluorine-based flame retardants such as PTFE; organosilicon-based flame retardants such as polyorganosiloxanes; metal hydroxide-based flame retardants such as aluminum hydroxide and magnesium hydroxide; other flame retardants; flame retardant additives such as cadmium oxide, zinc oxide, cuprous oxide, copper oxide, ferrous oxide, ferric oxide, cobalt oxide, manganese oxide, molybdenum oxide, tin oxide, and titanium dioxide; pigments, dyes, lubricants, release agents, compatibilizers, dispersants; crystal nucleating agents such as mica, talc, and kaolin; plasticizers such as phosphate esters; heat stabilizers; antioxidants; anti-coloring agents; ultraviolet absorbers; flow modifiers; foaming agents; antibacterial agents; vibration damping agents; deodorizers; sliding modifiers; and antistatic agents such as polyether ester amides. Especially when used in electrical and electronic equipment, automobiles, aircraft, etc., flame retardancy is sometimes required, and it is preferable to add phosphorus-based flame retardants, nitrogen-based flame retardants, or inorganic flame retardants.

[0125] Regarding the aforementioned flame retardant, in order to exhibit a flame retardant effect while maintaining a good balance with the mechanical properties of the resin used and the resin flowability during molding, the flame retardant is preferably set to 1 to 20 parts by weight, more preferably 1 to 15 parts by weight, relative to 100 parts by weight of the resin.

[0126] (Second thermoplastic resin)

[0127] The second thermoplastic resin is not particularly limited except that it is a thermoplastic resin as the main component. To improve the toughness of the thermosetting resin layer, a resin with high toughness is preferred. Furthermore, the island phase can be formed using a thermoplastic resin composition containing a thermoplastic resin as the main component. The thermoplastic resin composition may also include additives, depending on the application of the fiber-reinforced plastic.

[0128] There are no particular restrictions on the types of second thermoplastic resins that can be included as the main component in the island phase. Examples include: polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polypropylene terephthalate (PTT), polyethylene naphthalate (PEN), liquid crystal polyester, polyethylene (PE), polypropylene (PP), polybutene, polyolefins, polyoxymethylene (POM), polyamide (PA), polyphenylene sulfide (PPS), polyarylene sulfides, polyketone (PK), polyetherketone (PEK), polyetheretherketone (PEEK), polyarylene etherketone (PAEK), polyetherketone ketone (PEKK), and polyether nitrile (PEKK). Crystalline resins such as fluorinated resins such as polytetrafluoroethylene (PTFE), styrene resins and amorphous resins such as polycarbonate (PC), polymethyl methacrylate (PMMA), polyvinyl chloride (PVC), polyphenylene ether (PPE), polyimide (PI), polyamide-imide (PAI), polyether-imide (PEI), polysulfone (PSU), polyethersulfone, and polyarylate (PAR), as well as thermoplastic resins selected from phenolic resins, phenoxy resins, and thermoplastic elastomers such as polystyrene, polyolefin, polyurethane, polyester, polyamide, polybutadiene, polyisoprene, fluorinated resins, and acrylonitrile, their copolymers and modified products.

[0129] From the viewpoint of the lightweight nature of the resulting fiber-reinforced plastic, polyolefins are preferred. From the viewpoint of heat resistance, polyarylene sulfides such as polyphenylene sulfide (PPS), polyether ether ketone (PEEK), polyarylene ether ketone (PAEK), and polyether ketone ketone (PEKK) are preferred.

[0130] Furthermore, from the viewpoint of bonding strength, the second thermoplastic resin preferably has one or more resins selected from the group consisting of polyamide, polyarylate, polyamide-imide, polyimide, polyether-imide, polysulfone, and polyethersulfone as the main component. Among these, polyamide and polyimide are more preferred, and polyamide, which can significantly improve impact resistance due to its excellent toughness, is most preferred.

[0131] Furthermore, from the viewpoint of adhesion to the thermosetting resin layer, the island phase preferably contains a thermosetting resin, and more preferably a component containing a marine thermosetting resin. Additionally, the second thermoplastic resin preferably contains a thermosetting resin, and more preferably a component containing a marine thermosetting resin. Here, "marine thermosetting resin component" refers to a resin component of the same type as the thermosetting resin contained in the marine phase. For example, when the second thermoplastic resin forms a semi-IPN structure (interpenetrating polymer network structure) through combination with the thermosetting resin, it can suppress the delamination between the island phase and the marine phase, which is more preferable. Examples of combinations forming a semi-IPN structure include polyamides selected from polyamide 12, polyamide 6, polyamide 11, and polyamide 6 / 12 copolymers, and epoxy compounds.

[0132] The ratio (mass%) of the second thermoplastic resin to the thermosetting resin can be used in the range of 95:5 to 70:30, more preferably in the range of 90:10 to 80:20. Here, the thermosetting resin is not limited to epoxy compounds, but can also be selected from unsaturated polyesters, vinyl ester resins, benzoxazine resins, phenolic resins, urea resins, melamine resins, and polyimide resins. More preferably, the thermosetting resin composition is the same as that of the marine phase.

[0133] In addition, depending on its application, the second thermoplastic resin may also contain fillers such as mica, talc, kaolin, hydrotalcite, sericite, bentonite, calcium silicate, sepiolite, montmorillonite, wollastonite, silica, calcium carbonate, glass beads, glass sheets, glass microspheres, clay, molybdenum disulfide, titanium dioxide, zinc oxide, antimony oxide, calcium polyphosphate, graphite, barium sulfate, magnesium sulfate, zinc borate, calcium borate, aluminum borate whiskers, potassium titanate whiskers, and polymer compounds; conductive materials such as metal-based and metal oxide-based compounds; halogen-based flame retardants such as brominated resins; antimony-based flame retardants such as antimony trioxide and antimony pentaoxide; phosphorus-based flame retardants such as ammonium polyphosphate, aromatic phosphates, and red phosphorus; organic acid metal salt flame retardants such as organoborate metal salts, carboxylic acid metal salts, and aromatic sulfonylimide metal salts; zinc borate, zinc, zinc oxide, and zirconium. Inorganic flame retardants such as compounds, nitrogen-based flame retardants such as cyanuric acid, isocyanuric acid, melamine, melamine cyanurate, melamine phosphate and guanidine nitride, fluorine-based flame retardants such as PTFE, organosilicon-based flame retardants such as polyorganosiloxanes, metal hydroxide-based flame retardants such as aluminum hydroxide and magnesium hydroxide, and other flame retardants, flame retardant additives such as cadmium oxide, zinc oxide, cuprous oxide, copper oxide, ferrous oxide, ferric oxide, cobalt oxide, manganese oxide, molybdenum oxide, tin oxide and titanium dioxide, pigments, dyes, lubricants, release agents, compatibilizers, dispersants, crystal nucleating agents such as mica, talc and kaolin, plasticizers such as phosphate esters, heat stabilizers, antioxidants, anti-coloring agents, ultraviolet absorbers, flow modifiers, foaming agents, antibacterial agents, vibration damping agents, deodorizers, sliding modifiers, and antistatic agents such as polyether ester amides, etc. Especially when used in electrical and electronic equipment, automobiles, aircraft, etc., flame retardancy is sometimes required, and it is preferable to add phosphorus-based flame retardants, nitrogen-based flame retardants, or inorganic flame retardants.

[0134] Regarding the aforementioned flame retardant, in order to exhibit a flame retardant effect while maintaining a good balance with the mechanical properties of the resin used and the resin flowability during molding, the flame retardant is preferably set to 1 to 20 parts by weight, more preferably 1 to 15 parts by weight, relative to 100 parts by weight of the second thermoplastic resin.

[0135] (The shape of the island phase, which is mainly composed of the second thermoplastic resin)

[0136] The shape of the island phase, primarily composed of the second thermoplastic resin, is not particularly limited, as long as it forms an island structure dispersed within a marine phase primarily composed of a thermosetting resin. The island phase can be, for example, fiber-shaped or particle-shaped; however, from the viewpoint of suppressing disordered arrangement of reinforcing fibers, a spherical shape is preferred. For example, the cross-sectional shape of the island phase primarily composed of the second thermoplastic resin, observed in a cross-section perpendicular to the plane of the fiber-reinforced plastic, is more preferably circular, elliptical, or approximately circular with irregularities. Among these, a circular shape with fewer stress concentration points is further preferred.

[0137] From the viewpoint of improving the toughness of thermosetting resins, the elastic modulus of the island phase, which is mainly composed of the second thermoplastic resin, is preferably lower than that of the sea phase, which is mainly composed of the thermosetting resin, more preferably 70% or less of the elastic modulus of the sea phase, and even more preferably 50% or less.

[0138] As an example of determining the elastic modulus of the island phase, which is mainly composed of the second thermoplastic resin, and the marine phase, which is mainly composed of the thermosetting resin, a method can be given to evaluate the island phase, which is mainly composed of the second thermoplastic resin, and the marine phase, which is mainly composed of the thermosetting resin, in a cross-section obtained by cutting fiber-reinforced plastic using nanoindentation.

[0139] The glass transition temperature of the island phase, which is mainly composed of the second thermoplastic resin, is preferably lower than that of the marine phase, which is mainly composed of the thermosetting resin. By making the glass transition temperature of the island phase, which is mainly composed of the second thermoplastic resin, lower than that of the marine phase, which is mainly composed of the thermosetting resin, the toughness of the thermosetting resin layer can be further improved.

[0140] As an example of a method for determining the glass transition temperature of the island phase, which is mainly composed of a second thermoplastic resin, and the marine phase, which is mainly composed of a thermosetting resin, a method can be described as follows: extracting the island phase, which is mainly composed of a second thermoplastic resin, and the marine phase, which is mainly composed of a thermosetting resin, from a cross-section obtained by cutting fiber-reinforced plastic, and evaluating them using a differential scanning calorimeter (DSC).

[0141] (Rubber polymer)

[0142] Rubber polymers are preferably made with rubber polymers as the main component, but there are no other particular restrictions. Additives may also be added depending on the application. Rubber polymers are polymers containing polymers with a glass transition temperature below room temperature, and whose molecules are partially bound together by covalent bonds, ionic bonds, van der Waals forces, entanglement, etc.

[0143] Examples of rubber-based polymers include olefin resins, acrylic rubbers, silicone rubbers, fluorinated rubbers, nitrile rubbers, vinyl rubbers, urethane rubbers, polyamide elastomers, polyester elastomers, and ionomers.

[0144] Examples of additives that may be included in rubbery polymers include those that may be included in the second thermoplastic resin described above, and the same applies to preferred examples.

[0145] (Shape of rubbery polymer island phases)

[0146] The island phase with rubber polymer as the main component can have the same shape as the island phase with the second thermoplastic resin as the main component described above, and the preferred example is also the same.

[0147] In addition, the elastic modulus of the island phase, which is mainly composed of rubber polymer, is the same as that of the island phase, which is mainly composed of second thermoplastic resin, and is preferably lower than that of the island phase, which is mainly composed of thermosetting resin, and the preferred range is also the same.

[0148] The island phase, which is mainly composed of rubber polymers, is also preferably formed in a semi-IPN structure, just like the island phase, which is mainly composed of thermoplastic resins. The preferred range is also the same as that of thermoplastic resins.

[0149] [Thermoplastic resin layer]

[0150] The thermoplastic resin layer is not particularly limited except for containing the first thermoplastic resin. It is preferred to contain the first thermoplastic resin as the main component, and additives may be further included depending on the application of the fiber-reinforced plastic.

[0151] The first thermoplastic resin contained in the thermoplastic resin layer can be exemplified by the resin shown in the second thermoplastic resin described above, and the preferred example is also the same.

[0152] The additives that may be included in the first thermoplastic resin layer are the same as those that may be included in the second thermoplastic resin, and the preferred examples are also the same.

[0153] From the viewpoint of ensuring a suitable amount of resin for welding with the second component and improving color quality, the unit area weight of the thermoplastic resin layer in the fiber-reinforced plastic is preferably 10 g / m². 2 Above 500g / m 2 The following is more preferably 20g / m 2 Above 200g / m 2 the following.

[0154] Here, the weight per unit area refers to the weight per 1m². 2 The mass (g) of the thermoplastic resin layer contained in fiber-reinforced plastics.

[0155] In embodiments of the present invention, the thermoplastic resin layer may also be present as part of the surface layer of the fiber-reinforced plastic. The thermoplastic resin layer present on the surface of the fiber-reinforced plastic enables fusion-based integration with other components. Preferably, the portion of the thermoplastic resin layer is minimized, thereby improving the efficiency of the fiber-reinforced plastic with excellent mechanical properties.

[0156] <Manufacturing Method>

[0157] There are no particular limitations on the method for manufacturing the fiber-reinforced plastic according to the embodiments of the present invention. For example, the following manufacturing methods (I) to (IV) can be cited.

[0158] Manufacturing method (I)

[0159] The manufacturing method (I) is a method for manufacturing fiber-reinforced plastics, which includes: impregnating the precursor of the island phase and the precursor of the thermosetting resin layer on both sides of the reinforcing fiber sheet constituting the reinforcing fiber group to form the island phase and the thermosetting resin layer.

[0160] The process of softening or melting the precursor of the island phase and the precursor of the thermoplastic resin layer and disposing them on at least one side of a reinforcing fiber sheet having the island phase and the thermosetting resin layer formed thereon, thereby forming the island phase and the thermoplastic resin layer to produce an intermediate; and

[0161] The process of shaping the obtained intermediate.

[0162] Manufacturing Method (II)

[0163] Manufacturing method (II) is a method for manufacturing fiber-reinforced plastics, which includes: impregnating both sides of a reinforcing fiber sheet constituting a reinforcing fiber group with a precursor of an island phase and a precursor of a thermosetting resin layer to form an island phase and a thermosetting resin layer.

[0164] The process of softening or melting a precursor of a thermoplastic resin layer and depositing it on at least one side of a reinforcing fiber sheet having an island phase and a thermosetting resin layer, thereby forming a thermoplastic resin layer to produce an intermediate; and

[0165] The process of shaping the obtained intermediate.

[0166] Manufacturing Method (III)

[0167] Manufacturing method (III) is a method for manufacturing fiber-reinforced plastics, which includes: impregnating both sides of a reinforcing fiber sheet constituting a group of reinforcing fibers with a precursor of a thermosetting resin layer to form a thermosetting resin layer.

[0168] The process of softening or melting the precursor of the island phase and the precursor of the thermoplastic resin layer and disposing them on at least one side of a reinforcing fiber sheet having a thermosetting resin layer, thereby forming an island phase and a thermoplastic resin layer to produce an intermediate; and

[0169] The process of shaping the obtained intermediate.

[0170] Manufacturing method (IV)

[0171] The manufacturing method (IV) is a method for manufacturing fiber-reinforced plastics, which includes: impregnating one side of a reinforcing fiber sheet constituting a group of reinforcing fibers with a precursor of a thermoplastic resin layer, forming a thermoplastic resin layer, and then vibrating to disperse the precursor of the thermoplastic resin layer in the reinforcing fiber sheet.

[0172] The process of impregnating a precursor of a thermosetting resin layer onto another side of a reinforcing fiber sheet to form an intermediate; and

[0173] The process of shaping the obtained intermediate.

[0174] In embodiments of the present invention, there are no particular limitations on the method of forming a layer having an island structure in which an island phase, mainly composed of a second thermoplastic resin or a rubber polymer, is dispersed in a marine phase, mainly composed of a thermosetting resin. For example, in the aforementioned method for manufacturing fiber-reinforced plastics, any one of the methods described below (i) to (vii) can be used. In addition, various combinations of these methods are also possible.

[0175] (i) The process of making the precursor of the thermoplastic resin layer include the precursor of the island phase.

[0176] (ii) The process of making the precursor of the thermosetting resin layer include the precursor of the island phase.

[0177] (iii) A process of including an island phase in both the precursor of the thermosetting resin layer and the precursor of the thermoplastic resin layer.

[0178] (iv) The process of coating the precursor of the island phase onto at least one side of an intermediate composed of reinforcing fibers into which the precursor of the thermosetting resin layer is impregnated, and further impregnating the precursor of the thermoplastic resin layer.

[0179] (v) The process of coating the precursor of the island phase onto an intermediate formed by impregnating the precursor of the thermoplastic resin layer with the reinforcing fiber group.

[0180] (vi) The process of coating the precursor of the island phase onto one side of the precursor of the thermoplastic resin layer and further impregnating the precursor of the thermoplastic resin layer.

[0181] (vii) For an intermediate formed by impregnating a thermoplastic resin precursor with a reinforcing fiber assembly, a vibrating rod or the like is used to vibrate the intermediate to disperse the thermoplastic resin precursor in the reinforcing fiber assembly.

[0182] [Precursor for thermosetting resin layer]

[0183] The precursor of the thermosetting resin layer is a composition impregnated in a reinforcing fiber group to form a thermosetting resin layer. There are no particular limitations on the method of impregnating the precursor of the thermosetting resin layer into the reinforcing fiber group; for example, a method of using a hot roller to heat and pressurize the fiber group to soften or melt it for impregnation can be cited.

[0184] The precursor of the thermosetting resin layer is not limited in form as long as it can be impregnated into the reinforcing fiber group to become a thermosetting resin layer; for example, it can be in liquid, sheet, non-woven fabric, or particle form. However, from the viewpoint that it can be uniformly impregnated into the reinforcing fiber group, the precursor of the thermosetting resin layer is preferably in sheet form.

[0185] [Precursor for thermoplastic resin layer]

[0186] The precursor of the thermoplastic resin layer is a composition impregnated with a reinforcing fiber group to form a thermoplastic resin layer. There are no particular limitations on the method of impregnating the precursor of the thermoplastic resin layer with the reinforcing fiber group; for example, a method of impregnation by heating and pressurizing with a hot roller to melt it can be cited.

[0187] The precursor of the thermoplastic resin layer is not limited in form as long as it can be impregnated into the reinforcing fiber group to become a thermoplastic resin layer; for example, it can be liquid, sheet, non-woven fabric, or granular. However, from the viewpoint that it can be uniformly impregnated into the reinforcing fiber group, the precursor of the thermoplastic resin layer is preferably sheet-like.

[0188] Furthermore, in order to simultaneously form a thermoplastic resin layer and an island phase using the same precursor, the precursor for the island phase and / or the precursor for the thermoplastic resin layer is preferably in powder form. By setting the precursor to powder form, a portion of it can be impregnated into the thermosetting resin layer, and the remaining portion can be melted on the surface of the fiber-reinforced plastic to form a thermoplastic resin layer.

[0189] Regarding the melting temperature of the precursor of the thermoplastic resin layer, if the first thermoplastic resin, which is the main component of the precursor of the thermoplastic resin layer, is crystalline, it is preferable to heat and press mold at a temperature of 30°C or higher than its melting point; if the first thermoplastic resin is amorphous, it is preferable to heat and press mold at a temperature of 30°C or higher than its glass transition temperature.

[0190] In addition, the thermoplastic resin layer only needs to be configured in the portion that serves as the bonding surface with other components. In order to ensure stable heat fusion, a certain margin of bonding surface is sometimes reserved. From this point of view, it is preferable that the area of ​​the fiber-reinforced plastic surface layer is more than 50%, and more preferably more than 80%.

[0191] [Precursor to the island phase]

[0192] There are no particular limitations on the precursor of the island phase, as long as it can be an island phase present in the thermosetting resin layer of the fiber-reinforced plastic. Examples of the shape of the precursor of the island phase include liquid, sheet, nonwoven fabric, and particle. However, from the viewpoint of uniformly existing at the interface between the thermosetting resin layer and the thermoplastic resin layer, the precursor of the island phase is preferably in the form of particles, and more preferably in the form of powder.

[0193] When the precursor of the thermosetting resin layer includes the island phase precursor in advance, the island phase precursor is preferably in the range of 10 to 40 parts by mass relative to 100 parts by mass of the precursor of the thermosetting resin layer, more preferably in the range of 15 to 40 parts by mass, and even more preferably in the range of 25 to 40 parts by mass. By setting the amount of island phase in the above range, a balance between the adhesion between the intermediates of the fiber-reinforced plastic and the bonding strength of the fiber-reinforced plastic can be obtained.

[0194] Similarly, when the precursor of the thermoplastic resin layer includes the island phase precursor in advance, the island phase precursor is preferably in the range of 10 to 40 parts by weight relative to 100 parts by weight of the precursor of the thermoplastic resin layer, more preferably in the range of 15 to 40 parts by weight, and even more preferably in the range of 25 to 40 parts by weight. By setting the amount of island phase in the above range, a balance can be achieved between the adhesion between the intermediates of the fiber-reinforced plastic and the bonding strength of the fiber-reinforced plastic.

[0195] A preferred method for manufacturing the fiber-reinforced plastics according to embodiments of the present invention can be exemplified by molding methods using intermediates such as prepreg preforms with high impregnation content and semi-pregs with low impregnation content, as defined above. In this molding process, the fiber-reinforced plastics can be shaped into the desired structure and the curing reaction of the thermosetting resin can be promoted.

[0196] From the viewpoint of use as a structure, the glass transition temperature of the thermosetting resin is preferably 120°C or higher, more preferably 150°C or higher, and even more preferably 180°C or higher. Through this molding process, the glass transition temperature of the thermosetting resin can be controlled to be higher than that of the island-phase thermoplastic resin or rubber polymer.

[0197] The fiber-reinforced plastics according to embodiments of the present invention can be molded individually, or multiple sheets can be laminated together, or they can be laminated with other materials. Regarding the configuration of the laminates, there are no particular limitations except that the intermediate is placed on any of the outermost laminated units corresponding to the surface of the molded body; prepreg blanks, films, sheets, nonwoven fabrics, porous materials, metals, etc., can be laminated depending on the application.

[0198] The fiber-reinforced plastics involved in the embodiments of the present invention are not limited to examples of intermediate molding. Any embodiment of the present invention can be obtained by processes such as autoclaving, compression molding, pultrusion molding, resin transfer molding (RTM), and resin injection molding (RI) of prepreg preforms.

[0199] The structure of the fiber-reinforced plastic of the present invention is not particularly limited, and various structures can be selected according to the application, such as flat plate, curved plate, concave-convex structure, hollow structure, sandwich structure, etc.

[0200] The fiber-reinforced plastic of the present invention can be made into an integrally molded article with other components welded together by means of a thermoplastic resin layer disposed on the surface. There are no limitations on the joining method, and examples include hot plate welding, vibration welding, ultrasonic welding, laser welding, resistance welding, induction welding, insert injection molding, and matrix injection molding.

[0201] The fiber-reinforced plastics of the present invention are preferably used in computer applications such as aircraft structural components, windmill blades, automobile exterior panels and IC trays, and laptop casings, as well as in sports applications such as golf clubs and tennis rackets.

[0202] Example

[0203] The present invention will now be described in further detail with reference to the embodiments. However, the scope of the present invention is not limited to these embodiments.

[0204] <Reinforcing fiber bundles>

[0205] ·A-1

[0206] A reinforcing fiber bundle A-1, consisting of 24,000 continuous carbon fibers with a total number of monofilaments, was obtained by spinning, sintering, and surface oxidation of a polymer mainly composed of polyacrylonitrile. This bundle was used to form a reinforcing fiber assembly. The characteristics of this carbon fiber bundle A-1 are described below.

[0207] Single fiber diameter: 7μm

[0208] Density: 1.8 g / cm³ 3

[0209] Tensile strength: 4.2 GPa

[0210] Tensile modulus of elasticity: 230 GPa

[0211] Surface free energy: 15 mJ / m 2

[0212] Using A-1 as a base, various sizing agents were mixed with acetone to obtain a solution containing approximately 1% by mass of the compounds homogeneously. After coating the aforementioned carbon fiber bundles with each compound using an impregnation method, a heat treatment was performed at 210°C for 90 seconds, adjusting the amount of each compound applied to 0.5 parts by mass relative to 100 parts by mass of the carbon fiber to which each compound was applied. The sizing agents used in each carbon fiber and the surface free energy after sizing coating are described below.

[0213] ·A-2

[0214] Sorbitol polyglycidyl ether (“Denacol” (registered trademark) EX-614B, manufactured by Nagase ChemteX Co., Ltd.)

[0215] Surface free energy: 32 mJ / m 2

[0216] ·A-3

[0217] Bisphenol A diglycidyl ether (“jER” (registered trademark) 828, manufactured by Mitsubishi Chemical Co., Ltd.)

[0218] Surface free energy: 9 mJ / m 2

[0219] ·A-4

[0220] Polyethylene glycol diglycidyl ether (“Denacol” (registered trademark) EX-841, manufactured by Nagase ChemteX Co., Ltd.)

[0221] Surface free energy: 20 mJ / m 2

[0222] <Precursor of the island phase>

[0223] ·D-1

[0224] A homogeneous solution was obtained by adding 90 parts by weight of transparent polyamide (Grilamid TR55, manufactured by M Chemie Japan Co., Ltd.), 7.5 parts by weight of epoxy resin (jER 828, manufactured by Mitsubishi Chemical Co., Ltd.), and 2.5 parts by weight of curing agent (Tomide #296, manufactured by T&KTOKA Corporation) to a mixed solvent of 300 parts by weight of chloroform and 100 parts by weight of methanol. Next, using a spray gun, the homogeneous solution was atomized onto the surface of 3000 parts by weight of n-hexane under stirring, causing the solute to precipitate. The precipitated solid was filtered, thoroughly washed with n-hexane, and then vacuum-dried at 100°C for 24 hours to obtain spherical epoxy resin-modified polyamide particles with a semi-IPN structure, serving as precursor D-1 of the island phase, which is mainly composed of a second thermoplastic resin. The obtained island phase precursor D-1, which is mainly composed of the second thermoplastic resin, has an average particle size of 13 μm and a melting point of 250 °C.

[0225] ·D-2

[0226] Polyurethane microparticles (Dymic Beads (registered trademark) UCN-5150D, manufactured by Daihsei Chemical Co., Ltd.) were used as precursor D-2, which is an island phase mainly composed of rubber polymers. The average particle size of precursor D-2, which is an island phase mainly composed of rubber polymers, is 15 μm, and its glass transition temperature is -27 °C.

[0227] ·D-3

[0228] Low-melting-point polyamide (Amilan CM4000 (manufactured by Toray Co., Ltd.), ternary copolymer polyamide resin, melting point 155°C) was powdered and used as precursor D-3 for the island phase, which is mainly composed of thermoplastic resin. The average particle size of precursor D-3, which is mainly composed of thermoplastic resin, is 25 μm.

[0229] ·D-4

[0230] Polyamide 12 microparticles (SP-500 (manufactured by Toray Corporation), average particle size 5 μm, true spherical) were used as precursor D-4.

[0231] <Precursors for thermosetting resin layers>

[0232] ·B-1

[0233] 30 parts by weight of epoxy resin main agent (jER (registered trademark) 828 (manufactured by Mitsubishi Chemical Co., Ltd.)), 40 parts by weight of (jER (registered trademark) 1001 (manufactured by Mitsubishi Chemical Co., Ltd.)), and 30 parts by weight of (jER (registered trademark) 154 (manufactured by Mitsubishi Chemical Co., Ltd.)) were added to a mixing apparatus and heated and mixed at 150°C until the components were compatible. Then, while continuing to mix, the temperature was lowered to 80°C, and 26 parts by weight of curing agent (3,3'DAS (3,3'-diaminodiphenyl sulfone, manufactured by MITSUBISHI FINE CHEMICALS, INC Co., Ltd.)) was added and mixed at 80°C for 30 minutes to obtain precursor B-1 of the thermosetting resin layer.

[0234] B-2

[0235] 30 parts by weight of epoxy resin main agent (jER (registered trademark) 828 (manufactured by Mitsubishi Chemical Co., Ltd.)), 40 parts by weight of (jER (registered trademark) 1001 (manufactured by Mitsubishi Chemical Co., Ltd.)), and 30 parts by weight of (jER (registered trademark) 154 (manufactured by Mitsubishi Chemical Co., Ltd.)) were added to a mixing apparatus and heated and mixed at 150°C until the components were compatible. Then, 30 parts by weight of precursor D-1, which is mainly composed of thermoplastic resin, were added and mixed until D-1 was dispersed. Next, while continuing to mix, the temperature was lowered to 80°C, and 26 parts by weight of curing agent (3,3'DAS (3,3'-diaminodiphenyl sulfone, manufactured by MITSUBISHI FINE CHEMICALS, INC Co., Ltd.)) were added and mixed at 80°C for 30 minutes to obtain precursor B-2 containing a thermosetting resin layer of D-1.

[0236] B-3

[0237] 30 parts by weight of epoxy resin main agent (jER (registered trademark) 828 (manufactured by Mitsubishi Chemical Co., Ltd.)), 40 parts by weight of (jER (registered trademark) 1001 (manufactured by Mitsubishi Chemical Co., Ltd.)), and 30 parts by weight of (jER (registered trademark) 154 (manufactured by Mitsubishi Chemical Co., Ltd.)) were added to a mixing apparatus and heated and mixed at 150°C until the components were compatible. Then, after cooling to 80°C, 30 parts by weight of precursor D-2, which is mainly composed of thermoplastic resin, were added and mixed until D-2 was dispersed. Next, while continuing to mix, 26 parts by weight of curing agent (3,3'DAS (3,3'-diaminodiphenyl sulfone, MITSUBISHIFINE CHEMICALS, INC Co., Ltd.)) were added and mixed at 80°C for 30 minutes, thereby obtaining precursor B-3 containing a thermosetting resin layer of D-2.

[0238] B-4

[0239] 50 parts by weight of epoxy resin main agent (Araldite MY721 (Huntsman Advanced Materials), 50 parts by weight of jER 825 (Mitsubishi Chemical), and 7 parts by weight of Sumikaexcel PES5003P (Sumitomo Chemical)) were added to a mixing apparatus and heated and mixed at 150°C until the components were compatible. Then, while continuing to mix, the temperature was lowered to 80°C, and 45.1 parts by weight of curing agent (Seikacure S (Wakayama Seika Kogyo Co., Ltd.)) were added. The mixture was then mixed at 80°C for 30 minutes to obtain the thermosetting resin precursor B-4.

[0240] <Precursor for thermoplastic resin layer>

[0241] ·C-1

[0242] Low-melting-point polyamide (Amilan (registered trademark) CM4000 (manufactured by Toray Co., Ltd.), ternary copolymer polyamide resin, melting point 155°C) was sheeted to obtain precursor C-1 of thermoplastic resin layer.

[0243] ·C-2

[0244] 100 parts by weight of low-melting-point polyamide (Amilan CM4000 (Toray Corporation), ternary copolymer polyamide resin, melting point 155°C) and 30 parts by weight of thermoplastic resin precursor D-1 were fed into a twin-screw extruder and heated and kneaded at 180°C. The resulting compound was sheeted to obtain thermoplastic resin layer precursor C-2.

[0245] C-3

[0246] Low-melting-point polyamide (Amilan CM4000 (Toray Corporation), ternary copolymer polyamide resin, melting point 155°C) was powdered and used as precursor C-3 for the thermoplastic resin layer. The average particle size of precursor C-3 for the thermoplastic resin layer was 25 μm.

[0247] C-4

[0248] Polyamide 12 (Rilsamide (registered trademark) AMNO TLD (manufactured by Arkema Corporation), melting point 175°C) was sheeted to obtain C-4, the precursor of the thermoplastic resin layer.

[0249] C-5

[0250] Polyphenylene sulfide (Torelina (registered trademark) A670T05 (manufactured by Toray Co., Ltd.), melting point 278°C) was sheeted to obtain the precursor C-5 of the thermoplastic resin layer.

[0251] C-6

[0252] Polyetherketoneketone (Kepstan 7002 (manufactured by Arkema Corporation), melting point 332°C) was sheeted to obtain C-6, a precursor for thermoplastic resin layers.

[0253] <Preparation Method of Prepreg>

[0254] ·P-1

[0255] Reinforcing fiber bundles are arranged in one direction and split to form a continuous reinforcing fiber sheet. The unit area weight of the reinforcing fiber sheet is set at 200 g / m². 2 A thermosetting resin precursor was coated onto release paper using a doctor blade coater to create a thermosetting resin precursor film. This film was then laminated onto both sides of the reinforcing fiber sheet. Simultaneously, a prepreg intermediate containing the thermosetting resin precursor was obtained by heating and pressing with hot rollers at 80°C and 0.5 MPa. The prepreg of the reinforcing fiber sheet was set to a unit area weight of 50 g / m². 2 .

[0256] Next, the precursor of the thermoplastic resin layer is placed on a single surface of the intermediate of the prepreg preform, and pressure is applied at 0.5 MPa using a hot roller maintained at a melting point of +30°C or higher than that of the precursor of the thermoplastic resin layer. This results in a prepreg preform where the interface between the thermosetting resin layer and the thermoplastic resin layer is located within the reinforcing fiber group. The precursor of the thermoplastic resin layer has a weight of 50 g / m². 2 It is configured on a single surface of the prepreg intermediate.

[0257] P-2

[0258] Reinforcing fiber bundles are arranged in one direction and split to form a continuous reinforcing fiber sheet. The unit area weight of the reinforcing fiber sheet is set at 200 g / m². 2 A thermosetting resin precursor was coated onto release paper using a doctor blade coater to create a thermosetting resin precursor film. This film was then laminated onto both sides of the reinforcing fiber sheet. Simultaneously, a prepreg intermediate containing the thermosetting resin precursor was obtained by heating and pressing with hot rollers at 80°C and 0.5 MPa. The prepreg of the reinforcing fiber sheet was set to a unit area weight of 50 g / m². 2 .

[0259] Next, the island phase precursor, mainly composed of the second thermoplastic resin, is dispersed onto a single surface of the aforementioned prepreg intermediate using a feeder. The dispersion amount is 11.5 g / m³. 2 Distribute in a manner that allows for distribution.

[0260] Then, the precursor of the thermoplastic resin layer is disposed on the surface of the prepreg intermediate, which has an island phase mainly composed of a second thermoplastic resin. The precursor of the thermoplastic resin layer has a unit area weight of 38.5 g / m³. 2 The prepreg is configured on a single surface of the prepreg intermediate and pressurized at 0.5 MPa using a hot roller held at a melting point of +30°C above the thermoplastic resin layer precursor. This results in the interface between the thermosetting resin layer and the thermoplastic resin layer being located inside the reinforcing fiber group, and island phases with the second thermoplastic resin as the main component being dispersed in the sea phase with the thermosetting resin as the main component and existing near the interface of the prepreg.

[0261] P-3

[0262] Reinforcing fiber bundles are arranged in one direction and split to form a continuous reinforcing fiber sheet. The unit area weight of the reinforcing fiber sheet is set at 200 g / m². 2 A thermosetting resin layer precursor is coated onto release paper using a doctor blade coater to create a thermosetting resin layer precursor film. This film is then laminated onto both sides of the reinforcing fiber sheet. Simultaneously, a prepreg blank is obtained by heating and pressing with hot rollers at 80°C and 0.5 MPa, resulting in a prepreg blank in which only the thermosetting resin layer precursor is impregnated within the reinforcing fiber sheet. For the thermosetting resin layer precursor, B-1 is used.

[0263] P-4

[0264] In addition to using B-3 as a precursor for the thermosetting resin layer, a prepreg blank containing only the precursor for the thermosetting resin layer in the reinforcing fiber sheet was obtained using the same method as P-3.

[0265] ·P-5

[0266] Reinforcing fiber bundles are arranged in one direction and split to form a continuous reinforcing fiber sheet. The unit area weight of the reinforcing fiber sheet is set at 200 g / m². 2 A precursor for the thermoplastic resin layer is applied to a single surface of the aforementioned reinforcing fiber sheet. A hot roller, maintained at a temperature 30°C or higher above the melting point of the precursor, is then pressed at 0.5 MPa to obtain a prepreg intermediate containing the precursor for the thermoplastic resin layer within the reinforcing fiber sheet. The precursor for the thermoplastic resin layer has a weight of 50 g / m². 2 It is configured on a single surface of the prepreg intermediate.

[0267] After heating and pressurizing using the aforementioned hot rollers, the material is immediately passed through a periodically vibrating ultrasonic generator to disperse the thermoplastic resin precursor into the reinforcing fiber sheet. The ultrasonic generator is set to a frequency of 20 kHz, an amplitude of 100%, and a pressure of 1.0 MPa. The distance between the ultrasonic generator's horn and the prepreg intermediate is approximately 25 mm, and the ultrasonic vibration duration is approximately 1.0 second.

[0268] Next, a thermosetting resin layer precursor is coated onto release paper using a doctor blade coater to create a thermosetting resin layer precursor film. This film is then laminated onto the opposite side of the reinforcing fiber sheet containing the thermoplastic resin layer precursor. A hot roller is used to heat and pressurize the film at 80°C and 0.5 MPa, resulting in a prepreg intermediate formed by impregnating the thermosetting resin layer precursor into the reinforcing fiber sheet. The unit area weight of the prepared thermosetting resin layer precursor film is set to 50 g / m². 2 .

[0269] <Evaluation Methods>

[0270] (1) Determination of the volume ratio of island phase in fiber-reinforced plastics

[0271] In a cross section of the fiber-reinforced plastic orthogonal to the direction of the outermost fiber, the fiber closest to the surface of the fiber-reinforced plastic is designated as the outermost fiber. Within a measurement range of 100 μm from the center of the outermost fiber along a reference line horizontal to the surface of the fiber-reinforced plastic toward the thermosetting resin layer, the volume percentage (volume %) of the island phase is determined.

[0272] (2) Methods for determining the bonding strength of fiber-reinforced plastics

[0273] Cut the prepreg blanks into the specified size, and prepare 2 prepreg blanks made by any one of the methods described above, P-1, P-2 or P-5, and 6 prepreg blanks made by the methods described above, P-3 or P-4.

[0274] The fiber direction of the reinforcing fiber is set to 0°, and the direction orthogonal to the fiber direction is defined as 90°, with [0° / 90°] as the reference. 2s (The symbol 's' indicates mirror symmetry) Prepreg blanks are laminated to create a prepreg blank laminate. In this case, the two outermost sheets on each side are laminated using prepreg blanks prepared according to the methods described above (P-1, P-2, or P-5), and the surface layer of the laminate is configured as a thermoplastic resin layer. This laminate is placed in a compression molding die, and clamps and spacers are used as needed. While maintaining the shape, a pressure of 0.6 MPa is applied using a press, and the mixture is heated at 180°C for 2 hours to obtain fiber-reinforced plastic.

[0275] The aforementioned fiber-reinforced plastic was cut into two 250mm wide and 100mm long pieces along the length of the test piece, with the angle relative to the fiber direction of the reinforcing fibers being 0°. These two pieces were then dried in a vacuum oven for 24 hours and then stacked together with a overlap length of 12.5mm. A pressure of 3MPa was applied at a temperature 20°C higher than the melting point of the thermoplastic resin layer and held for 1 minute, thereby fusing the overlapping surfaces to obtain a joint. A flap was then bonded to the joint according to ISO 4587:1995 (JIS K6850 (1994)) and cut to a width of 25mm to obtain the test piece.

[0276] The obtained test pieces were dried in a vacuum oven for 24 hours, and the bond strength (MPa) was evaluated at an ambient temperature of 23°C based on ISO 4587:1995 (JIS K6850 (1994)).

[0277] (Example 1)

[0278] Using A-1 as the reinforcing fiber bundle, B-2 as the precursor for the thermosetting resin layer, C-1 as the precursor for the thermoplastic resin layer, and D-1 as the precursor for the island phase, a prepreg preform was prepared using the method described in P-2 above. Using the prepared prepreg preform, test pieces were made corresponding to various evaluation criteria, and then evaluated.

[0279] The interface between the thermosetting resin layer and the aforementioned thermoplastic resin layer of the obtained prepreg blank is located inside the reinforcing fiber group formed by carbon fiber bundle A-1. The thermosetting resin layer has an island structure in which island phases with the second thermoplastic resin as the main component are dispersed in marine phases with the thermosetting resin as the main component. In addition, island phases with the thermoplastic resin as the main component are contained near the interface between the thermoplastic resin layer and the thermosetting resin layer.

[0280] When the precursor of the thermosetting resin layer is impregnated into the reinforcing fiber sheet, the island phase mainly composed of thermoplastic resin contained in the precursor B-2 of the thermosetting resin layer is biased on the surface of the reinforcing fiber sheet, thus resulting in excellent bonding strength.

[0281] (Example 2)

[0282] Using A-1 as the reinforcing fiber bundle, B-2 as the precursor for the thermosetting resin layer, C-2 as the precursor for the thermoplastic resin layer, and D-1 as the precursor for the island phase, a prepreg preform was prepared using the method described in P-2 above. Using the prepared prepreg preform, test pieces were made corresponding to various evaluation criteria, and then evaluated.

[0283] The interface between the thermosetting resin layer and the aforementioned thermoplastic resin layer of the obtained prepreg blank is located inside the reinforcing fiber group formed by carbon fiber bundle A-1. The thermosetting resin layer has an island structure in which island phases with the second thermoplastic resin as the main component are dispersed in marine phases with the thermosetting resin as the main component. In addition, island phases with the thermoplastic resin as the main component are contained near the interface between the thermosetting resin layer and the thermoplastic resin layer.

[0284] When the precursor of the thermosetting resin layer is impregnated into the reinforcing fiber sheet, the island phase mainly composed of the second thermoplastic resin contained in the precursor of the thermosetting resin layer is biased on the surface of the reinforcing fiber sheet. Furthermore, the thermoplastic resin layer also contains island phase mainly composed of the second thermoplastic resin, thus resulting in excellent bonding strength.

[0285] (Example 3)

[0286] Using A-1 as the reinforcing fiber bundle, B-3 as the precursor for the thermosetting resin layer, C-1 as the precursor for the thermoplastic resin layer, and D-2 as the precursor for the island phase, a prepreg preform was prepared using the method described in P-2 above. Using the prepared prepreg preform, test pieces were made corresponding to various evaluation criteria, and then evaluated.

[0287] The interface between the thermosetting resin layer and the aforementioned thermoplastic resin layer of the obtained prepreg blank is located inside the reinforcing fiber group formed by carbon fiber bundle A-1. The thermosetting resin layer has an island structure in which island phases mainly composed of rubbery polymers are dispersed within marine phases mainly composed of thermosetting resins. In addition, island phases mainly composed of rubbery polymers are also present near the interface between the thermosetting resin layer and the thermoplastic resin layer.

[0288] When the precursor of the thermosetting resin layer is impregnated into the reinforcing fiber sheet, the island phase mainly composed of rubber polymer contained in the precursor B-3 of the thermosetting resin layer is biased on the surface of the reinforcing fiber sheet, thus resulting in excellent bonding strength.

[0289] (Example 4)

[0290] Using A-1 as the reinforcing fiber bundle, B-1 as the precursor for the thermosetting resin layer, C-3 as the precursor for the thermoplastic resin layer, and D-3 as the precursor for the island phase with thermoplastic resin as the main component, prepreg preforms were prepared using the method described in P-2 above. Using the prepared prepreg preforms, test pieces corresponding to various evaluation criteria were made and evaluated.

[0291] The interface between the thermosetting resin layer and the aforementioned thermoplastic resin layer of the obtained prepreg blank is located inside the reinforcing fiber group formed by carbon fiber bundle A-1. The thermosetting resin layer has an island structure in which island phases with the second thermoplastic resin as the main component are dispersed in marine phases with the thermosetting resin as the main component. In addition, island phases with the thermoplastic resin as the main component are contained near the interface between the thermosetting resin layer and the thermoplastic resin layer.

[0292] When the precursor of the thermoplastic resin layer is impregnated into the reinforcing fiber sheet, since the precursor of the thermoplastic resin layer is in powder form, a portion of it penetrates into the thermosetting resin layer, forming an island phase mainly composed of thermoplastic resin near the interface between the thermosetting resin layer and the thermoplastic resin layer, thus resulting in excellent bonding strength.

[0293] (Example 5)

[0294] Using A-1 as the reinforcing fiber bundle, B-1 as the precursor for the thermosetting resin layer, C-1 as the precursor for the thermoplastic resin layer, and D-1 as the precursor for the island phase with thermoplastic resin as the main component, prepreg preforms were prepared using the method described in P-2 above. Using the prepared prepreg preforms, test pieces were made corresponding to various evaluation criteria, and evaluations were conducted.

[0295] The interface between the thermosetting resin layer and the aforementioned thermoplastic resin layer of the obtained prepreg blank is located inside the reinforcing fiber group formed by carbon fiber bundle A-1. The thermosetting resin layer has an island structure in which island phases with the second thermoplastic resin as the main component are dispersed in marine phases with the thermosetting resin as the main component. In addition, island phases with the thermoplastic resin as the main component are contained near the interface between the thermosetting resin layer and the thermoplastic resin layer.

[0296] When the precursor of the thermosetting resin layer is impregnated into the reinforcing fiber sheet, the island phase mainly composed of the second thermoplastic resin contained in the precursor of the thermosetting resin layer is biased on the surface of the reinforcing fiber sheet. Furthermore, the thermoplastic resin layer also contains island phase mainly composed of the second thermoplastic resin, thus resulting in excellent bonding strength.

[0297] (Example 6)

[0298] Using A-1 as the reinforcing fiber bundle, B-1 as the precursor for the thermosetting resin layer, C-1 as the precursor for the thermoplastic resin layer, and D-2 as the precursor for the island phase mainly composed of a rubbery polymer, a prepreg preform was prepared using the method described in P-2 above. Using the prepared prepreg preform, test pieces corresponding to various evaluation criteria were made and evaluated.

[0299] The interface between the thermosetting resin layer and the aforementioned thermoplastic resin layer of the obtained prepreg blank is located within the reinforcing fiber group formed by carbon fiber bundles A-1. The thermosetting resin layer has an island structure in which island phases, mainly composed of rubbery polymers, are dispersed within marine phases, mainly composed of thermosetting resins. Furthermore, island phases, mainly composed of rubbery polymers, are present near the interface between the thermosetting and thermoplastic resin layers. These rubbery polymer-based island phases are predominantly located near the interface between the thermosetting and thermoplastic resin layers. The presence of island phases in both the thermosetting and thermoplastic resin layers results in excellent bonding strength.

[0300] (Example 7)

[0301] Except for using A-3 as the reinforcing fiber, C-1 as the precursor of the thermoplastic resin layer, and D-1 as the precursor of the island phase, prepreg blanks were prepared for various evaluations using the same method as in Example 4.

[0302] The interface between the thermosetting resin layer and the aforementioned thermoplastic resin layer of the obtained prepreg blank is located inside the reinforcing fiber group formed by carbon fiber bundle A-3, and has an island structure in which island phases are dispersed in a marine phase mainly composed of thermosetting resin. In addition, island phases mainly composed of thermoplastic resin are contained near the interface between the thermosetting resin layer and the thermoplastic resin layer.

[0303] When the precursor of the thermoplastic resin layer is impregnated into the reinforcing fiber sheet, since the precursor of the thermoplastic resin layer is in powder form, a portion of it penetrates into the thermosetting resin layer, forming an island phase mainly composed of thermoplastic resin near the interface between the thermosetting resin layer and the thermoplastic resin layer, thus resulting in excellent bonding strength.

[0304] (Example 8)

[0305] Except for using A-2 as the reinforcing fiber, C-4 as the precursor of the thermoplastic resin phase, and D-4 as the precursor of the island phase, prepreg blanks were prepared using the same method as in Example 4 for various evaluations.

[0306] The interface between the thermosetting resin layer and the thermoplastic resin layer of the obtained prepreg blank is located inside the reinforcing fiber group formed by carbon fiber bundles A-2, exhibiting an island structure with island phases dispersed within a marine phase dominated by thermosetting resin. Furthermore, island phases dominated by thermoplastic resin are present near the interface between the thermosetting resin layer and the thermoplastic resin layer. It is believed that by using carbon fiber A-2, which has high affinity for both thermosetting and thermoplastic resins, carbon fiber dispersion is ensured, resin flowability is improved, and island phase formation is promoted.

[0307] When the precursor of the thermoplastic resin layer is impregnated into the reinforcing fiber sheet, since the precursor of the thermoplastic resin layer is in powder form, a portion of it penetrates into the thermosetting resin layer, forming an island phase mainly composed of thermoplastic resin near the interface between the thermosetting resin layer and the thermoplastic resin layer, thus resulting in excellent bonding strength.

[0308] (Example 9)

[0309] Using A-4 as the reinforcing fiber bundle, B-3 as the precursor for the thermosetting resin layer, and C-5 as the precursor for the thermoplastic resin layer, a prepreg preform was prepared using the method described in P-5 above. Test pieces were then prepared from the prepared prepreg preform to correspond to various evaluation criteria, and these were evaluated.

[0310] The interface between the thermosetting resin layer and the thermoplastic resin layer of the obtained prepreg blank is located inside the reinforcing fiber group formed by carbon fiber bundle A-3, and has an island structure in which island phases are dispersed in a marine phase mainly composed of thermosetting resin. In addition, island phases mainly composed of thermoplastic resin are contained near the interface between the thermosetting resin layer and the thermoplastic resin layer.

[0311] When the precursor of the thermoplastic resin layer is impregnated into the reinforcing fiber sheet, vibration is used to disperse a portion of it into the reinforcing fiber sheet, forming island phases mainly composed of thermoplastic resin near the interface between the thermosetting resin layer and the thermoplastic resin layer, thus resulting in excellent bonding strength.

[0312] (Example 10)

[0313] Except that C-6 was used as a precursor for the thermoplastic resin phase, prepreg blanks were prepared using the same method as in Example 9 for various evaluations.

[0314] The interface between the thermosetting resin layer and the thermoplastic resin layer of the obtained prepreg blank is located inside the reinforcing fiber group formed by carbon fiber bundle A-4, and has an island structure in which island phases are dispersed in a marine phase mainly composed of thermosetting resin. In addition, island phases mainly composed of thermoplastic resin are contained near the interface between the thermosetting resin layer and the thermoplastic resin layer.

[0315] When the precursor of the thermoplastic resin layer is impregnated into the reinforcing fiber sheet, vibration is used to disperse a portion of it into the reinforcing fiber sheet, forming island phases mainly composed of thermoplastic resin near the interface between the thermosetting resin layer and the thermoplastic resin layer, thus resulting in excellent bonding strength.

[0316] (Comparative Example 1)

[0317] Using A-1 as the reinforcing fiber bundle, B-1 as the precursor for the thermosetting resin layer, and C-1 as the precursor for the thermoplastic resin layer, a prepreg preform was prepared using the method described in P-1 above. Test pieces were then prepared using the prepared prepreg preforms, corresponding to various evaluation criteria, and evaluated.

[0318] The resulting prepreg blanks and test pieces do not contain island phases, resulting in low bonding strength.

[0319] (Comparative Examples 2-4)

[0320] Prepreg blanks were prepared as shown in Table 1, and various evaluations were performed using these prepreg blanks. The interface between the thermosetting resin layer and the aforementioned thermoplastic resin layer of the obtained prepreg blanks is located inside the reinforcing fiber assembly formed by carbon fiber bundles, and does not contain island phases other than the thermoplastic resin layer and the thermosetting resin layer.

[0321] [Table 1]

[0322]

[0323] The present invention has been described in detail and with reference to specific embodiments, but those skilled in the art will understand that various changes and modifications can be made without departing from the spirit and scope of the invention. This application is based on Japanese Patent Application No. 2020-096946, filed on June 3, 2020, the contents of which are incorporated herein by reference.

[0324] Explanation of reference numerals in the attached figures

[0325] 1. Reinforcing fibers

[0326] 3. Thermosetting resin layer

[0327] 4. Thermoplastic resin layer

[0328] 5. Fiber-reinforced plastics

[0329] 6. Interface

[0330] 7. Island phase

[0331] 8. Marine compounds with thermosetting resins as the main component

[0332] 9. Surface of fiber-reinforced plastics

[0333] 10. Outermost fiber

[0334] 11. Baseline

[0335] 12. Measurement range

Claims

1. A fiber-reinforced plastic comprising a group of reinforcing fibers, a thermosetting resin layer, and a thermoplastic resin layer containing a first thermoplastic resin. in, The fiber-reinforced plastic has the thermoplastic resin layer as its surface layer. The interface between the thermoplastic resin layer and the thermosetting resin layer is located inside the reinforcing fiber assembly. The thermosetting resin layer has an island structure in which an island phase, mainly composed of a second thermoplastic resin or rubber polymer, is dispersed in a marine phase, mainly composed of a thermosetting resin. The melting point of the second thermoplastic resin and the rubber polymer is higher than that of the first thermoplastic resin. The island phase is located near the interface between the thermosetting resin layer and the thermoplastic resin layer. In the thickness direction section, within a range of 100 μm from the outermost fiber toward the thermosetting resin layer, the volume percentage of the island phase is 1% or more relative to 100% by volume.

2. The fiber-reinforced plastic as described in claim 1, wherein, The second thermoplastic resin is a resin of the same type as the first thermoplastic resin.

3. The fiber-reinforced plastic as described in claim 2, wherein, The second thermoplastic resin is the same as the first thermoplastic resin.

4. The fiber-reinforced plastic according to any one of claims 1 to 3, wherein, The island phase contains components of the thermosetting resin of the marine phase.

5. The fiber-reinforced plastic according to any one of claims 1 to 3, wherein, The average grain size of the island phase in the thickness direction section is 0.1 μm to 10 μm.

6. The fiber-reinforced plastic according to any one of claims 1 to 3, wherein, The length of the major axis of the island phase is between 3 μm and 30 μm.

7. The fiber-reinforced plastic according to any one of claims 1 to 3, wherein, The elastic modulus of the island facies is lower than that of the marine facies.

8. The fiber-reinforced plastic according to any one of claims 1 to 3, wherein, The glass transition temperature of the island phase is lower than that of the marine phase.

9. The fiber-reinforced plastic according to any one of claims 1 to 3, wherein its surface free energy, as determined by the Wilhelmy method, is 10 to 50 mJ / m. 2 The reinforcing fiber is used as the reinforcing fiber.

10. A method for manufacturing fiber-reinforced plastic, comprising the method for manufacturing fiber-reinforced plastic according to any one of claims 1 to 9, the method comprising: The process of impregnating the precursor of the island phase and the precursor of the thermosetting resin layer on both sides of the reinforcing fiber sheet constituting the reinforcing fiber group to form the island phase and the thermosetting resin layer. The process of softening or melting the precursor of the island phase and the precursor of the thermoplastic resin layer and disposing them on at least one side of the reinforcing fiber sheet on which the island phase and the thermosetting resin layer are formed, thereby forming the island phase and the thermoplastic resin layer to produce an intermediate. and The process of shaping the obtained intermediate.

11. A method for manufacturing fiber-reinforced plastic, as described in any one of claims 1 to 9, comprising: The process of impregnating the precursor of the island phase and the precursor of the thermosetting resin layer on both sides of the reinforcing fiber sheet constituting the reinforcing fiber group to form the island phase and the thermosetting resin layer. The process of softening or melting the precursor of the thermoplastic resin layer and disposing it on at least one side of the reinforcing fiber sheet on which the island phase and the thermosetting resin layer are formed, thereby forming the thermoplastic resin layer to produce an intermediate. and The process of shaping the obtained intermediate.

12. A method for manufacturing fiber-reinforced plastic, comprising the method for manufacturing fiber-reinforced plastic according to any one of claims 1 to 9, the method comprising: The process of impregnating the precursor of the thermosetting resin layer onto both sides of the reinforcing fiber sheet constituting the reinforcing fiber group to form the thermosetting resin layer; The process of softening or melting the precursor of the island phase and the precursor of the thermoplastic resin layer and disposing them on at least one side of the reinforcing fiber sheet on which the thermosetting resin layer is formed, thereby forming the island phase and the thermoplastic resin layer to produce an intermediate. and The process of shaping the obtained intermediate.

13. A method for manufacturing fiber-reinforced plastic, comprising the method for manufacturing fiber-reinforced plastic according to any one of claims 1 to 9, the method comprising: The process of impregnating one side of a reinforcing fiber sheet constituting the reinforcing fiber group with the precursor of the thermoplastic resin layer, forming the thermoplastic resin layer, and then vibrating it to disperse the precursor of the thermoplastic resin layer in the reinforcing fiber sheet. The process of impregnating the precursor of the thermosetting resin layer onto the other side of the reinforcing fiber sheet to form an intermediate; and The process of shaping the obtained intermediate.

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