Methods for manufacturing fiber-reinforced resin substrates, preforms, integrally molded articles, and fiber-reinforced resin substrates

Abstract

The purpose of this invention is to provide a fiber-reinforced resin substrate formed by robustly combining multiple resins with different properties. This invention is a fiber-reinforced resin substrate formed by impregnating thermoplastic resin (A) and thermoplastic resin (B) into continuous reinforcing fibers. A layer of thermoplastic resin (A) with one surface exposed and a layer of thermoplastic resin (B) with the other surface exposed form a boundary region. At least a portion of the aforementioned continuous reinforcing fibers extends across the aforementioned boundary region. Both thermoplastic resin (A) and thermoplastic resin (B) are crystalline resins with a melting point of 200°C or higher.

Description

Technical Field

[0001] This invention relates to a fiber-reinforced resin substrate made by impregnating a reinforcing fiber with a thermoplastic resin, a preform and an integrally molded article using the same, and a method for manufacturing the fiber-reinforced resin substrate. Prior Technology

[0002] Fiber-reinforced resin composites, which use thermosetting or thermoplastic resins as the matrix resin and combine them with reinforcing fibers such as carbon fiber or glass fiber, are widely used in many fields, including aerospace, automotive, railway vehicles, shipbuilding, civil engineering, and sporting goods, due to their lightweight and mechanical properties such as strength and rigidity. However, these fiber-reinforced composites are not suitable for manufacturing parts or structures with complex shapes in a single molding step. In such applications, it is necessary to manufacture components made of fiber-reinforced composites and then integrate them with other components. At this time, it is also possible to combine resins with different properties as needed. As a method of integrating fiber-reinforced composites with other components, mechanical joining methods using bolts, rivets, screws, etc., or adhesive joining methods are used. In mechanical joining methods, the need for pre-processing steps such as drilling holes in the joining parts leads to long processing times and increased manufacturing costs. Moreover, the drilling holes can reduce the material strength. In bonding methods using adhesives, the bonding process involves both adhesive preparation or coating and a hardening step, resulting in a long processing time and potentially insufficient reliability in achieving the required bonding strength.

[0003] In fiber-reinforced composite materials using thermoplastic resins as the matrix, in addition to the methods mentioned above, hot-melt bonding can also be used to join components, thus potentially shortening the bonding time between components. While hot-melt bonding methods include two-color molding to obtain molded products made from different types of thermoplastic resins, the mainstream approach, when combining resins with high compatibility or low compatibility, is to integrate them through shape design such as interlocking, which results in limited design freedom.

[0004] Patent Document 1 discloses a technique for bonding components made of different thermoplastic resins together by using fiber-reinforced resin sheets made by impregnating a plurality of different thermoplastic resins in a nonwoven fabric composed of reinforcing fibers. [Previous Technical Documents] [Patent Literature]

[0005] Patent Document 1: International Publication No. 2014 / 103658 Summary of the Invention

[0006] [The problem the invention aims to solve]

[0007] However, in such dissimilar bonding, a further increase in bonding strength is required. The object of this invention is to provide a fiber-reinforced resin substrate for strongly bonding dissimilar fiber-reinforced resin components using different thermoplastic resins, particularly those using different thermoplastic resins as matrix resins. [Methods used to solve problems]

[0008] This invention relates to a fiber-reinforced resin substrate, which is formed by impregnating thermoplastic resin (A) and thermoplastic resin (B) into continuous reinforcing fibers. The thermoplastic resin (A) layer composed of thermoplastic resin (A) with one surface exposed and the thermoplastic resin (B) layer composed of thermoplastic resin (B) with the other surface exposed form a boundary region. At least a portion of the aforementioned continuous reinforcing fibers exists across the aforementioned boundary region. Both thermoplastic resin (A) and thermoplastic resin (B) are crystalline resins with a melting point of 200°C or higher.

[0009] Furthermore, another aspect of the present invention is a method for manufacturing a fiber-reinforced resin substrate, which is a method for manufacturing a fiber-reinforced resin substrate by impregnating a continuous reinforcing fiber with thermoplastic resin (A) and thermoplastic resin (B). The method is characterized by: impregnating one side of the continuous reinforcing fiber sheet with thermoplastic resin (A) to obtain a semi-impregnated material in which one side of the thermoplastic resin (A) layer is exposed and the other side of the continuous reinforcing fiber sheet is exposed; or impregnating one side of the continuous reinforcing fiber sheet with thermoplastic resin (B) to obtain a semi-impregnated material in which one side of the thermoplastic resin (B) layer is exposed and the other side of the continuous reinforcing fiber sheet is exposed; and then impregnating the other side of the semi-impregnated material with thermoplastic resin (A). [Effects of the Invention]

[0010] By using the fiber-reinforced resin substrate of the present invention, it is possible to produce an integral molded article in which two thermoplastic resin components are firmly joined together. Simple Explanation of the Diagram

[0011] Figure 1 illustrates the method for determining the interlaminar shear strength of the thermoplastic resin (A) layer and the thermoplastic resin (B) layer of the fiber-reinforced resin substrate of the present invention; the reinforcing fiber is omitted. Figure 2 is a model diagram of the fiber-reinforced resin substrate of the present invention, which helps to illustrate the method for measuring the average roughness length RSm and average height Rc of the fiber-reinforced resin substrate. Figure 3 is a model diagram of a cross-section perpendicular to the plane of the fiber-reinforced resin substrate of the present invention. (a) is a cross-section of the radial direction of the reinforcing fiber, and (b) is a cross-section of the longitudinal direction of the reinforcing fiber, which helps to illustrate the opposing surface and the boundary region. Figure 4 is a model diagram of a cross-section perpendicular to the plane of the fiber-reinforced resin substrate of the present invention, which helps to illustrate the method for measuring the average roughness length RSm and the average roughness height Rc. Figure 5 is a model diagram illustrating the method for manufacturing a bonding strength test piece of an integrally molded article according to the present invention. Implementation

[0012] [The form in which the invention is carried out]

[0013] The fiber-reinforced resin substrate of the present invention will be described below. In the following specification, "~" indicates a range including the values ​​at both ends.

[0014] The fiber-reinforced resin substrate of the present invention comprises at least continuous reinforcing fibers, thermoplastic resin (A) and thermoplastic resin (B).

[0015] <Reinforced Fibers> Examples of reinforcing fibers used in this invention include glass fiber, carbon fiber, metal fiber, aromatic polyamide fiber, polyarylamide fiber, alumina fiber, silicon carbide fiber, boron fiber, and basalt fiber. These can be used alone or in combination of two or more. Carbon fiber is more suitable as a reinforcing fiber due to its low specific gravity, high strength, and high modulus of elasticity. Commercially available carbon fibers include Torayca T800G-24K, Torayca T800S-24K, Torayca T700G-24K, Torayca T700S-24K, Torayca T300-3K, and Torayca T1100G-24K (all manufactured by Toray Industries, Inc.).

[0016] Reinforcing fibers may also be those with surface treatments. Surface treatments include metal coating, coupling agent treatment, sizing agent treatment, and additive attachment treatment. Furthermore, in this specification, reinforcing fibers with an attached surface treatment agent are referred to as reinforcing fibers containing a surface treatment agent.

[0017] These reinforcing fibers are preferably those with a surface free energy of 10-50 mJ / m², as determined by the Wilhelmy method. Because this range is controlled, the reinforcing fibers exhibit high affinity with thermoplastic resins (A) and (B), demonstrating high bonding strength, particularly at the interface where the reinforcing fibers cross the boundaries between the existing thermoplastic resin (A) and (B) layers. The surface free energy of the reinforcing fibers is preferably 15-40 mJ / m², more preferably 18-35 mJ / m². Below 10 mJ / m², the affinity between the reinforcing fibers and thermoplastic resins (A) or (B) decreases, resulting in insufficient bonding strength. Above 50 mJ / m², the reinforcing fibers aggregate, exhibiting poor dispersion in the fiber-reinforced resin matrix, leading to greater deviations in bonding strength.

[0018] Methods for controlling the surface free energy of reinforcing fibers include surface oxidation treatment, adjusting the amount of oxygen-containing functional groups such as carboxyl or hydroxyl groups, and attaching elemental or compound compounds to the fiber surface. When multiple compounds are attached to the surface, those with high and low surface free energy can be mixed to achieve adhesion.

[0019] The surface free energy can be calculated using Owens' approximation after measuring the contact angles of the reinforcing fiber with three types of solvents (pure water, ethylene glycol, and tricresyl phosphate). Specifically, it can be determined using the method described in the examples below.

[0020] The fiber-reinforced resin substrate of this invention contains reinforcing fibers in a continuous form. That is, the reinforcing fibers can exist as unidirectionally arranged fiber bundles, laminates of fiber bundles, or in the form of fabrics, and can be used in a ribbon or sheet-like state. In this specification, reinforcing fibers having these forms are collectively referred to as continuous reinforcing fibers. In the case of reinforcing fiber bundles, they can be composed of multiple fibers of the same form, or multiple fibers of different forms. The number of reinforcing fibers constituting a single reinforcing fiber bundle is typically 300 to 60,000, but considering the manufacturing of the substrate, it is preferably 300 to 48,000, and more preferably 1,000 to 24,000.

[0021] Furthermore, when the tensile strength of the reinforcing fiber, as measured by the resin impregnation strand test method according to JIS R7608 (2007), is 5.5 GPa or higher, in addition to the improvement of mechanical properties such as the tensile strength of the fiber-reinforced resin matrix itself, excellent interlaminar shear strength of the thermoplastic resin (A) layer and (B) layer is also obtained, making it more suitable. The preferred tensile strength of this strand is 5.8 GPa or higher.

[0022] The fiber-reinforced resin substrate of this invention preferably has a reinforcing fiber content of 30 g / m² per unit area. If the reinforcing fiber content is 30 g / m² or higher, the thermoplastic resin (A) layer and (B) layer can be more robustly composited, and subsequent operations for obtaining preforms or integrally molded articles become easier. There is no particular upper limit to the reinforcing fiber content, but if it is 2,000 g / m² or lower, the thermoplastic resin (A) and (B) can be easily impregnated into the reinforcing fibers, while maintaining the lightweight nature of the fiber-reinforced resin substrate.

[0023] The volume fraction of reinforcing fibers in the thermoplastic resin (A) layer and the thermoplastic resin (B) layer of the present invention is preferably 30% to 90% by volume, more preferably 35% to 85% by volume, and even more preferably 40% to 80% by volume. If the volume fraction of reinforcing fibers is 30% by volume or more, the amount of resin relative to the amount of fiber is not excessive, making it easier to obtain a fiber-reinforced resin substrate with excellent specific strength and specific modulus of elasticity. If the volume fraction of reinforcing fibers is 90% by volume or less, poor resin impregnation is less likely to occur, the formation of voids can be suppressed, and a fiber-reinforced resin substrate in which the thermoplastic resin (A) layer and (B) layer are strongly bonded can be obtained. The volume fraction of reinforcing fibers in each layer can be determined by the method described in the examples described later.

[0024] <Thermoplastic Resin (A) and Thermoplastic Resin (B)> The thermoplastic resin (A) and thermoplastic resin (B) of this invention are combinations of "different thermoplastic resins". Here, "different" means that thermoplastic resin (A) and thermoplastic resin (B) exclude: using resins with the same composition and the same viscosity or melting point, i.e., fiber-reinforced resin substrates that are merely layers of identical thermoplastic resins; as long as such a state is not present, thermoplastic resin (A) and thermoplastic resin (B) are essentially unrestricted. More specifically, it refers to using one grade of commercially available thermoplastic resin as the state of thermoplastic resin (A) and thermoplastic resin (B). Furthermore, when referred to simply as "thermoplastic resin" in this specification, it includes both thermoplastic resin (A) and (B).

[0025] For example, even resins with the same composition (i.e., the same repeating units) are called different thermoplastic resins if they have different viscosities or melting points. However, as long as the resins with the same composition are manufactured using the same method, even if there are very slight differences in viscosity or melting point due to variations in manufacturing conditions, they are still the same resins. Furthermore, even if they are the same polyamide, Nylon 6 and Nylon 66 are different resins.

[0026] However, the effectiveness of this invention changes significantly when thermoplastic resin (A) and thermoplastic resin (B) are different types of resin. The similarity or difference in resin types is determined by the similarity of characteristic structures. For example, if it is a polyamide resin, it is determined to be a resin containing repeating units comprising amide; if it is a polyester resin, it is determined to be a resin containing repeating units comprising ester bonds. Because these are resins with repeating units having different bonds, they are thus determined to be different types of resin.

[0027] As a thermoplastic resin, it is preferable to use a thermoplastic resin whose main chain generally has bonds selected from the group consisting of carbon-carbon bonds, amide bonds, amide bonds, ester bonds, ether bonds, carbonate bonds, carbamate bonds, thioether bonds, ion bonds, and carbonyl bonds. Thermoplastic resins may also partially have a cross-linked structure without hindrance. In particular, it is preferable to use at least one resin selected from the group consisting of polyamide, polyacetal, polyphenylene sulfide, polyester, polyetherketone, polyetheretherketone, polyaryl etherketone, polyarylamide, and polyethernitrile.

[0028] Furthermore, the thermoplastic resin may be a copolymer or modified product of the above-mentioned resins and / or a blend of two or more types of resins. When using a blend of two or more types of resins, the resin with the largest mass among the resins constituting each thermoplastic resin shall be regarded as that thermoplastic resin. If the resins with the largest mass in each thermoplastic resin (A) and (B) are not the same, then it is determined that the two resins are of different types.

[0029] In this invention, the difference in melting points between thermoplastic resin (A) and thermoplastic resin (B) is preferably 10~50℃. Here, the "melting point" and "glass transition temperature" in this specification can be determined by differential scanning calorimetry (DSC) according to JIS K7121 (2012). 1~10 mg of sample is placed in a sealed sample container with a volume of 50 μl, and the temperature is increased at a rate of 10℃ / min. The step difference of the DSC curve detected in the range of 30~400℃ is taken as the glass transition temperature, the exothermic peak is taken as an indicator of the melting point, and the respective temperatures are taken as the glass transition temperature and melting point.

[0030] For convenience, in this case, a resin with a high melting point will be described as thermoplastic resin (B). Preferably, the melting point of thermoplastic resin (B) is at least 30°C higher than that of thermoplastic resin (A). When the difference in melting points is less than 10°C, at the temperature condition where only the thermoplastic resin (A) layer melts in order to bond with other components, the thermoplastic resin (B) layer also melts or undergoes thermal deformation. This results in a decrease in the mechanical properties of the molded article due to shape deformation of the fiber-reinforced resin substrate, and a decrease in bonding strength due to the disorder of the reinforcing fibers or changes in the interface state of the fiber-reinforced resin substrate. From the viewpoint of increasing the design freedom of temperature conditions during resin combination or bonding, it is preferable that thermoplastic resin (B) has a melting point at least 40°C higher than that of thermoplastic resin (A), and more preferably at least 45°C higher. If the difference in melting points between the aforementioned thermoplastic resin (A) and the aforementioned thermoplastic resin (B) is less than 50°C, then the thermal decomposition of the other thermoplastic resin at the temperature condition where one melts can be suppressed.

[0031] Of these, thermoplastic resin (A) is preferably selected from the group consisting of poly(aryl ether ketone) or polyphenylene sulfide, polyether ether ketone, and polyether ketone ketone, and thermoplastic resin (B) is also preferably selected from this group. By selecting this thermoplastic resin, a fiber-reinforced resin matrix can be obtained that maintains high mechanical properties under heat resistance and high temperature and humidity conditions. Furthermore, poly(aryl ether ketone) has excellent chemical resistance and abrasion resistance, and polyphenylene sulfide has excellent chemical resistance; therefore, when combined with other thermoplastic resins with poor chemical resistance or abrasion resistance, their properties can be compensated for.

[0032] By combining resins with different properties, such as different melting points, viscosities, or resin types, fiber-reinforced thermoplastic resins can adapt to applications or applications that were previously difficult to adapt to. When combining resins or resin types with different melting points, by placing a low-melting-point resin on the side of the resin layer to be bonded to other components, only the resin layer to be bonded can melt, while maintaining the appearance of the resin layer on the opposite side. When combining resins or resin types with different viscosities, the impregnation time of the reinforcing fibers can be shortened by using a low-viscosity resin or resin type, thus shortening the production process time of the fiber-reinforced resin substrate. Fiber-reinforced resin substrates with these different properties are particularly suitable for locations at the boundary of environmental or usage conditions, such as the interior of cylindrical bodies or containers such as pipes exposed to oil or chemicals, high-temperature and humid steam, etc., and the boundary of operating temperature in refrigerators or ovens where thermal insulation is required.

[0033] From the viewpoint of good heat resistance and minimal heat deformation, the thermoplastic resins (A) and (B) of the present invention have a preferred glass transition temperature of 100°C or higher, more preferably 150°C or higher, and even more preferably 180°C or higher. Examples of crystalline thermoplastic resins with a glass transition temperature of 100°C or higher include polyketones, polyetherketones, polyetheretherketones, polyetherketones, polyetherketones, polyaryl ether ketones, alicyclic polyamides, semi-aromatic polyamides, and polyphenylene sulfides.

[0034] Thermoplastic resins (A) and (B) are preferably crystalline resins with a melting point of 200°C or higher, from the viewpoint of good heat resistance. Crystalline resins also possess high mechanical properties, allowing for continuous use for extended periods even in high-temperature environments required for applications such as aerospace. Specifically, the melting point of thermoplastic resins (A) and (B) is preferably 250°C or higher, more preferably 300°C or higher, and especially preferably 350°C or higher. There is no specific upper limit to the melting point, but the upper limit for typical thermoplastic resins is 400°C.

[0035] From the viewpoint of suppressing heating when integrated with other components or the reduction of physical properties under high temperature environment when used as an integrally molded article, the thermoplastic resins (A) and (B) of the present invention preferably have a thermal decomposition start temperature of 480°C or higher, more preferably 500°C or higher, and even more preferably 550°C or higher.

[0036] In thermoplastic resins, elastomers or rubber components may be added to improve impact resistance. Furthermore, depending on the intended use, other fillers or additives may be suitably included without prejudice to the purpose of this invention. Examples include inorganic fillers, flame retardants, conductivity enhancers, nucleating agents, ultraviolet absorbers, antioxidants, vibration damping agents, antibacterial agents, insect repellents, deodorizing agents, anti-coloring agents, heat stabilizers, mold release agents, antistatic agents, plasticizers, lubricants, colorants, pigments, dyes, foaming agents, defoaming agents, coupling agents, etc.

[0037] In the fiber-reinforced resin substrate of the present invention, the unit area weight of each thermoplastic resin (A) and (B) forming each layer is preferably 10 g / m² or more. If the unit area weight of each resin is 10 g / m² or more, the boundary region between the thermoplastic resin (A) layer and the (B) layer can be formed, especially the interface where the thermoplastic resin (A) layer and the (B) layer meet, resulting in a sufficient thickness to exhibit excellent bonding strength. Furthermore, a sufficient layer thickness for integration with other components is obtained. More preferably, it is 20 g / m² or more, and even more preferably 50 g / m² or more. There is no particular upper limit, but to ensure that the amount of thermoplastic resin is not excessive compared to the reinforcing fiber, and to obtain a fiber-reinforced resin substrate with excellent specific strength and specific modulus of elasticity, it is preferably 1000 g / m² or less. Here, unit area weight refers to the mass (g) of thermoplastic resin contained in 1 m² of the fiber-reinforced resin substrate.

[0038] <Fiber-reinforced resin substrate> In the fiber-reinforced resin substrate of the present invention, a thermoplastic resin (A) and a thermoplastic resin (B) different from the thermoplastic resin (A) are impregnated in continuous reinforcing fibers. Simultaneously, a layer of thermoplastic resin (A) composed of thermoplastic resin (A) is exposed on one surface, and a layer of thermoplastic resin (B) composed of thermoplastic resin (B) is exposed on the other surface. Furthermore, the thermoplastic resin (A) layer and the thermoplastic resin (B) layer form a boundary region.

[0039] Furthermore, at least a portion of the aforementioned continuous reinforcing fibers exists across the boundary region between the thermoplastic resin (A) layer and the thermoplastic resin (B) layer. This "boundary region," as shown in Figure 3, includes: the surface of the fiber-reinforced substrate 1 opposite to the surface of the thermoplastic resin (A) layer 3, i.e., the opposing surface 12 of the thermoplastic resin (A) layer in Figure 3, and the surface opposite to the surface of the thermoplastic resin (B) layer 4, i.e., the opposing surface 13 of the thermoplastic resin (B) layer in Figure 3, and the area of ​​air (void) 15 between them. This opposing surface is the surface where the resin layer contacts the air (void) or the opposing surface of another resin.

[0040] The phrase "existing across the boundary region" is illustrated in Figures 3(a) and (b). In Figure 3(b), the reinforcing fiber 2 (shown as a dashed line) exists in either the thermoplastic resin (A) layer 3 or the thermoplastic resin (B) layer 4, that is, it exists across the boundary region 14 between the resin layers. Because the reinforcing fiber 2 exists across the boundary region 14, the thermoplastic resin (A) layer 3 and the thermoplastic resin (B) layer 4 are physically bonded through the reinforcing fiber 2.

[0041] As shown in Figure 4, the thermoplastic resin (A) layer 3 and the thermoplastic resin (B) layer 4 form an interface 5 and are bonded together, which is preferable because the thermoplastic resins are chemically and / or physically bonded to each other. Here, "forming an interface and bonding" means that there is no air (void) in the boundary region 14, and the thermoplastic resin (A) layer 3 and the thermoplastic resin (B) layer 4 are bonded together, and the opposing surfaces of each resin layer, that is, the opposing surface 12 of the thermoplastic resin (A) layer and the opposing surface 13 of the thermoplastic resin (B) layer are closely bonded to each other.

[0042] Regarding the "formation of interface and bonding", Figure 4 is used to illustrate this. In the observation image 8 of Figure 4, the thermoplastic resin (A) layer 3, which is composed of thermoplastic resin (A), forms an interface 5 and bonds with the thermoplastic resin (B) layer 4. Moreover, a plurality of continuous reinforcing fibers 2 are present on the interface 5. Thus, the state in which the thermoplastic resin (A) layer 3 and the thermoplastic resin (B) layer 4 are in contact with the reinforcing fibers can be described as the state in which the reinforcing fibers "exist across the interface".

[0043] Because the continuous reinforcing fibers exist across the interface between the two resin layers, the bonding strength between the thermoplastic resin layers is enhanced. The continuous reinforcing fibers present at the interface are chemically and / or physically bonded to thermoplastic resin (A) and thermoplastic resin (B), thereby enhancing the adhesion between the thermoplastic resin (A) layer and the thermoplastic resin (B) layer. The number of continuous reinforcing fibers present at the interface is preferably 4 or more within a 500μm × 500μm observation range (described later), which is preferable from the viewpoint of exhibiting a strong bond between the thermoplastic resin (A) layer and the thermoplastic resin (B) layer; more preferably 10 or more; and even more preferably 30 or more. There is no particular upper limit to the number of fibers, but from the viewpoint of exhibiting strong bonding strength and suppressing excessive orientation of the reinforcing fibers to obtain a fiber-reinforced resin substrate with a good appearance, it is preferable to have 200 or fewer fibers.

[0044] In the fiber-reinforced resin substrate of the present invention, the interlaminar shear strength of the aforementioned thermoplastic resin (A) layer and thermoplastic resin (B) layer, as measured according to JIS K7092 (2005), is preferably 30 MPa or more. Due to this interlaminar shear strength, an integrally molded article can be obtained in which components made of different thermoplastic resins are strongly bonded together. The interlaminar shear strength is more preferably 40 MPa or more, and even more preferably 50 MPa or more. There is no particular limitation on the upper limit of the interlaminar shear strength, but 100 MPa or less is sufficient. The interlaminar shear strength is measured using a notched test piece 23, as shown in FIG. 1, which has a notch 6 extending to the interface 5 of the fiber-reinforced resin substrate 1, and can be measured by the method described in the embodiments described later.

[0045] The fiber-reinforced resin substrate of the present invention is observed in a top view of the fiber-reinforced resin substrate from a 45-degree angle relative to the fiber direction of any continuous reinforcing fiber, whether clockwise or counterclockwise, in a cross-section perpendicular to the plane of the fiber-reinforced resin substrate containing the aforementioned continuous reinforcing fibers, that is, in a cross-section obtained by cutting perpendicular to the plane direction of the fiber-reinforced resin substrate. The state of the resin layer at the interface can be evaluated simultaneously in the direction of fiber axial force and the direction orthogonal to it.

[0046] The fiber-reinforced resin substrate of the present invention preferably has a roughness average length RSm of less than 100 μm and a roughness average height Rc of more than 3.5 μm as defined by JIS B0601 (2001) for the cross-sectional curve of the interface between the two resin layers. If RSm is less than 100 μm, not only chemical and / or physical bonding forces, but also mechanical bonding forces caused by the mutual intrusion of each resin layer are applied, making it difficult to peel the thermoplastic resin (A) layer and the thermoplastic resin (B) layer. There is no particular limitation on the lower limit of RSm, but from the viewpoint of avoiding the reduction of mechanical bonding force caused by stress concentration, it is preferably more than 15 μm. Furthermore, since the Rc of the cross-sectional curve is 3.5 μm or more, it not only demonstrates the mechanical bonding force due to entanglement, but also enhances the adhesion between the thermoplastic resin (A) layer and the thermoplastic resin (B) layer through the chemical and / or physical bonding of the continuous reinforcing fibers present at the interface with the thermoplastic resin (A) and thermoplastic resin (B). As a preferred range for Rc, it is 10 μm or more, and preferably 20 μm or more, where the continuous reinforcing fibers are easily contained in the two resin layers and the adhesion is further enhanced. There is no particular upper limit to the value of Rc, but from the viewpoint of avoiding the reduction of mechanical bonding force caused by stress concentration, it is preferable to be 100 μm or less.

[0047] Here, the method for measuring the average roughness height Rc and average roughness length RSm of the profile curve can be a well-known technique. For example, methods can be used to measure them from cross-sectional images obtained using X-ray CT, from elemental analysis mapping images obtained from an energy dispersive X-ray spectrometer (EDS), or from cross-sectional images obtained from an optical microscope, scanning electron microscope (SEM), or transmission electron microscope (TEM). During observation, thermoplastic resin (A) and / or thermoplastic resin (B) can also be stained to adjust contrast. In the image obtained by any of the above methods, the average roughness height Rc and average roughness length RSm of the profile curve are measured within a 500 μm × 500 μm range. The calculation of Rc and RSm from the cross-sectional observation image can be performed using the method described in the examples described later.

[0048] As a method to make the average roughness height Rc and average roughness length RSm of the profile curve of the present invention fall within a better range, examples include increasing the pressure of the pressurizing roller or increasing the pressure during the step of impregnating the continuous reinforcing fiber with thermoplastic resin, or setting the surface temperature of the heating and pressurizing components of the roller or the like to a high level to reduce the viscosity of the thermoplastic resin.

[0049] From the viewpoint of operability and exhibiting strong bonding strength when used for joining multiple components, the thickness of the fiber-reinforced resin substrate of the present invention is preferably 500 μm or less, more preferably 400 μm or less, and even more preferably 300 μm or less. There is no particular limitation on the lower limit of the thickness, but operability is also good and more suitable if it is 20 μm or more.

[0050] The thickness of the thermoplastic resin (A) layer in the fiber-reinforced resin substrate is preferably 20-80% of the thickness of the fiber-reinforced resin substrate. From the viewpoint of suppressing warping, the thickness can also be adjusted according to the molding shrinkage rate of the resin used. Furthermore, since thinner layers are easier to melt, the proportion of the resin layer thickness can be reduced if a shorter melting time is desired, or the proportion of the thickness can be increased if a harder-to-melt layer is desired.

[0051] <Pre-form> The fiber-reinforced resin substrate of the present invention can be formed by laminating metal components, fiber-reinforced thermosetting resin components using thermosetting resin as the matrix resin, and fiber-reinforced thermoplastic resin components using thermoplastic resin as the matrix resin to form a preform. In particular, in the case of joining a component A having thermoplastic resin (A) on its surface and a component B having thermoplastic resin (B) on its surface, the fiber-reinforced resin substrate of the present invention is configured to form a preform in such a way that the thermoplastic resin (A) layer of the fiber-reinforced resin substrate is in contact with the thermoplastic resin (A) of component A, and the thermoplastic resin (B) layer is in contact with the thermoplastic resin (B) of component B, thereby maximizing the effect of the present invention.

[0052] <One-piece molded product> Furthermore, by bonding multiple components using the fiber-reinforced resin substrate of the present invention, a one-piece molded article can be formed. Typically, such a one-piece molded article can be obtained by heating and pressurizing the aforementioned preform using the molding method described later.

[0053] In this invention, a component A having thermoplastic resin (A) on its surface and a component B having thermoplastic resin (B) on its surface are integrally molded by fusing the thermoplastic resin (A) layer of the fiber-reinforced resin substrate with the thermoplastic resin (A) layer of component A and the thermoplastic resin (B) layer of component B, thereby maximizing the effects of the invention. In a preferred embodiment, one or both of components (A) and (B) are also made of fiber-reinforced resin, resulting in an integrally molded article with excellent strength. From the viewpoint of suppressing the thermal decomposition of the thermoplastic resin, a method can be used where, after joining the fiber-reinforced resin substrate with one of components A or B, the other component is sequentially integrated; or a method can be used where the aforementioned preform with the fiber-reinforced resin substrate disposed between components A and B is heated and pressurized for simultaneous integration. In this case, the resin can further impregnate the continuous reinforcing fibers within the fiber-reinforced resin substrate, forming an interface.

[0054] Examples of molding methods for integrally molded articles according to the present invention include thermal welding, vibration welding, ultrasonic welding, laser welding, resistance welding, induction welding, insertion injection molding, external insertion injection molding, two-color molding, pressure molding, autoclave molding, bagging molding, wrapping, internal pressure molding, manual lay-up, filament winding, pultrusion, resin injection molding, and resin transfer molding.

[0055] <Manufacturing Method of Fiber-Reinforced Resin Substrate> The fiber-reinforced resin substrate of the present invention, as an example, can be manufactured by: impregnating one side of a continuous reinforcing fiber sheet with thermoplastic resin (A) to obtain a semi-impregnated material with one side of the thermoplastic resin (A) layer exposed and the other side of the continuous reinforcing fiber sheet exposed, and then impregnating the other side of the semi-impregnated material with thermoplastic resin (B); or impregnating one side of a continuous reinforcing fiber sheet with thermoplastic resin (B) to obtain a semi-impregnated material with one side of the thermoplastic resin (B) layer exposed and the other side of the continuous reinforcing fiber sheet exposed, and then impregnating the other side of the semi-impregnated material with thermoplastic resin (A) as described above. In this case, when the thermoplastic resin (B) has a higher melting point than the thermoplastic resin (A), as explained above, the possibility of thermal decomposition or thermal degradation of the thermoplastic resin (B) due to the heating temperature applied to the impregnated thermoplastic resin (A) after the higher melting point thermoplastic resin (B) has been reduced, thus making it more preferable.

[0056] There are no particular limitations on the method of impregnating thermoplastic resin from one side. Methods include applying thermoplastic resin in the form of film, nonwoven fabric, or particles to the surface of a continuous reinforcing fiber sheet, followed by heating and pressurization; or applying molten or dissolved liquid thermoplastic resin to the surface of the continuous reinforcing fiber sheet, followed by heating and pressurization to impregnate it. Well-known methods can be used for heating. Examples include using far-infrared heaters, high-temperature ovens, non-contact heating methods using induction heating, and methods involving contact with heated rollers or belts. Heating in the tank of a far-infrared heater or high-temperature oven is preferable from a temperature control perspective. There are no particular limitations on the pressurization method; methods using reverse rollers, forward-rotating rollers, kissing rollers, applicators, or belts can be used. Furthermore, when the viscosity of the molten thermoplastic resin is low, pressurization is not always necessary. Alternatively, one could cite a method of impregnating a surface with thermoplastic resin by reducing pressure from the side opposite to the surface to which the thermoplastic resin is applied or applied.

[0057] There are no particular limitations on the method of impregnating thermoplastic resin from the other side; the same method as the aforementioned method of impregnating thermoplastic resin from one side can be used. From the viewpoint of suppressing the thermal decomposition or thermal degradation of the first impregnated thermoplastic resin, the temperature can be set to melt and dissolve only the thermoplastic resin impregnated from the other side, or the heat source can be placed only on the other side, etc., and can be adjusted arbitrarily. [Example]

[0058] The present invention will now be described in more detail by way of examples. However, the scope of the present invention is not limited to these examples. Furthermore, unless otherwise specified, the unit "parts" in the composition ratio refers to parts by mass. In addition, unless otherwise specified, the determination of various properties is carried out at an environment of 23°C and 50% relative humidity.

[0059] <Evaluation and Measurement Methods> (1) Interlaminar shear strength of fiber-reinforced resin substrate The interlaminar shear strength of the thermoplastic resin (A) layer and thermoplastic resin (B) layer of the fiber-reinforced resin substrate was measured according to JIS K7092 (2005). In the fiber-reinforced resin substrate of the present invention and its comparative products, the longitudinal direction of the test piece was aligned with the fiber direction of the continuous reinforcing fibers. A prepreg composed of carbon fiber and epoxy resin was laminated to a thickness of 2 mm and then press-molded to obtain a hardened board. The surface of the obtained hardened board was roughened by sandblasting and degreased. An acrylic adhesive was applied to the surface of the hardened board and bonded to both surfaces of the fiber-reinforced resin substrate. The adhesive was then cured to produce a test board for testing. As shown in FIG1, the obtained test board was formed with notches of 1 mm width, 6.4 mm spacing, and 0 to 0.2 mm depth by a cutting machine, parallel and alternating from both surfaces, with the notch tip reaching the interface between the two layers on the thermoplastic resin (A) layer side and the (B) layer side. Then, a test piece with a length of 80 mm and a width of 12.5 mm was cut out.

[0060] Compression tests were conducted using notched test specimens. The interlaminar shear strength was calculated from the obtained load and the dimensions of the test specimen. The number of tests was n=5, and the average value was taken as the interlaminar shear strength of the fiber-reinforced resin matrix.

[0061] (2) Melting point and glass transition temperature of thermoplastic resins The melting point and glass transition temperature of thermoplastic resins were determined using a differential scanning calorimeter (DSC) according to JIS K7121 (2012). 1–10 mg of sample was placed in a sealed 50 μl sample container, and the temperature was increased at a rate of 10 °C / min. The step difference of the DSC curve detected in the range of 30–400 °C was taken as the glass transition temperature, and the exothermic peak was taken as an indicator of the melting point. The respective temperatures were then used as the glass transition temperature and melting point.

[0062] (3) Roughness average length RSm and roughness average height Rc of fiber-reinforced resin substrate Using the prepared fiber-reinforced resin substrate, as shown in Figure 2, a cut was made perpendicular to the plane of the fiber-reinforced resin substrate at a 45-degree angle in the top view of the substrate, with an observation cross-section 8. The test piece, embedded in epoxy resin, was then ground to observe the cross-section. Using an optical microscope, 10 images at 10x magnification points were captured within the obtained cross-section.

[0063] The appearance of any 500μm × 500μm observation area in the obtained image is shown in the model diagram in Figure 4. In this observation screen 8, the thermoplastic resin (A) layer 3 and the thermoplastic resin (B) layer 4 form an interface 5. Here, the end of the thermoplastic resin (B) layer 4 composed of thermoplastic resin (B) is taken as the reference line 9, and vertical baselines 10 are drawn at 5μm intervals from the thermoplastic resin (B) layer 4 composed of thermoplastic resin (B) towards the thermoplastic resin (A) layer 3 composed of thermoplastic resin (A). The point where the vertical baseline 10 drawn from the reference line 9 first intersects the thermoplastic resin (A) layer 3 is plotted, and the line connecting the plotted points is taken as the profile curve 11. For the obtained profile curve 11, filtering is performed according to JIS B0601 (2001), and the average roughness height Rc and average roughness length RSm of the profile curve 11 are calculated. Similarly, the average roughness height Rc and average roughness length RSm are calculated from the images obtained at the 10 locations, and the average values ​​are used as the individual values.

[0064] (4) Volume content of reinforcing fibers in thermoplastic resin layers (A) and (B) A 20mm square piece was cut from a fiber-reinforced resin substrate, embedded in epoxy resin, and then ground to prepare a sample. The sample was observed by grinding a cross-section perpendicular to the fiber direction of the reinforcing fibers in the fiber-reinforced resin substrate. The sample was magnified to 400x using a laser microscope (KEYENCE, VK-9510) to observe the cross-section. The observation image was unfolded using general image analysis software, and the cross-section of the reinforcing fibers seen in the observation image was extracted using a program integrated into the software, and the total area was calculated. Similarly, the area of ​​the thermoplastic resin (A) layer was measured from the outer periphery (the area enclosed by the two ends of the observation cross-section, the surface of the thermoplastic resin (A) layer, and the interface with the thermoplastic resin (B) layer). From these measured areas, the proportion of the total area of ​​reinforcing fibers per area of ​​the thermoplastic resin (A) layer was calculated. The same measurements were performed at 5 observation points, and the average value was taken as the volume content of reinforcing fibers in the thermoplastic resin (A) layer of the present invention. Furthermore, the thermoplastic resin (B) layer was measured using the same method.

[0065] (5) The thickness of the thermoplastic resin (A) layer and its ratio relative to the thickness of the fiber-reinforced resin substrate. The average value of the plotting positions of the cross-sectional curves used in (3) above is taken as the boundary between the thicknesses of the thermoplastic resin (A) layer and the thermoplastic resin (B) layer. The distance from one surface of the fiber-reinforced resin substrate (the exposed surface of the thermoplastic resin (A)) to the thickness boundary is taken as the thickness of the thermoplastic resin (A) layer. Furthermore, the thickness of the fiber-reinforced resin substrate is measured using a micrometer, and the thickness ratio is calculated from these measured values.

[0066] (6) Bond strength of integrally molded parts The obtained fiber-reinforced resin substrate is used as a bonding member and is disposed in mold 12 as shown in FIG. 5(a). On the thermoplastic resin (A) layer side, thermoplastic resin (A) and carbon fiber (20% by mass) are melt-blended in an extruder, and the resulting carbon fiber reinforced thermoplastic resin (A) pellets 17 are injection molded. On the thermoplastic resin (B) layer side, thermoplastic resin (B) and carbon fiber (20% by mass) are melt-blended in an extruder, and the resulting carbon fiber reinforced thermoplastic resin (B) pellets 19 are injection molded to produce a test piece 21 for measuring the bonding strength of the integrally molded article.

[0067] Tensile tests were performed on the obtained test specimens, and the joint strength was calculated from the obtained fracture load and the area of ​​the joint. The obtained joint strength was evaluated as follows. A pressure of 50 MPa or higher, or failure of the base material of the injection-molded component: A 40MPa or higher but less than 50MPa, or failure of the base material of the injection-molded component: B 30MPa or higher but less than 40MPa, or failure of the base material of the injection-molded component: C Less than 30MPa: D (Unqualified).

[0068] (7) Strengthen the surface free energy of fibers Using a DataPhysics DCAT11, a single fiber was first taken from the reinforcing fiber bundle and cut into eight fibers of 12 ± 2 mm in length. These fibers were then attached parallel to each other on a dedicated holder FH12 (a flat plate coated with an adhesive material), spaced 2-3 mm apart. The leading ends of the fibers were then trimmed and placed in the DCAT11 holder. The measurement involved bringing a cell containing each solvent close to the lower end of the eight fibers at a speed of 0.2 mm / s, immersing the fibers to a depth of 5 mm from the leading end. The fibers were then lifted at 0.2 mm / s, and this process was repeated at least four times. The force F acting on the fiber immersed in the liquid was measured using an electronic balance, and the contact angle θ was calculated using the following formula.

[0069] COS θ = (Force F (mN) on 8 single fibers) / (8 (number of single fibers) × circumference of single fiber (m) × surface tension of solvent (mJ / m²)) Furthermore, the measurements were performed on individual fibers extracted from different locations within the 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.

[0070] The surface free energy γf of the reinforcing fiber is calculated as the sum of the polar component γpf and the nonpolar component γdf of the surface free energy.

[0071] The polar component of the surface free energy, γpf, is obtained by substituting the surface tension components and contact angles of each liquid into the Owens approximation (a formula composed of the polar and non-polar components of the inherent surface tension of each solvent, and then the contact angle θ), plotting it on X and Y axes, and then calculating the square of the slope a when approximating a straight line using the least squares method. The non-polar component of the surface free energy, γdf, is obtained by the square of slice b. The surface free energy γf of the reinforcing fiber is the sum of the square of the slope a and the square of slice b. Y = a·X + b X = √(polar component of solvent surface tension (mJ / m²)) / √(nonpolar component of solvent surface tension (mJ / m²)) Y = (1 + COS θ) · (polar component of solvent surface tension (mJ / m 2)) / 2√(non-polar component of solvent surface tension (mJ / m 2)) The polar component of the surface free energy of reinforcing fibers is γpf = a². The nonpolar component of the surface free energy of reinforcing fibers is γdf=b². The total surface free energy γf = a² + b²

[0072] The polar and non-polar components of the surface tension of each solvent are as follows. Pure water Surface tension: 72.8 mJ / m², polar component: 51.0 mJ / m², non-polar component: 21.8 mJ / m² · Ethylene glycol Surface tension: 48.0 mJ / m², polar component: 19.0 mJ / m², non-polar component: 29.0 mJ / m² Trimethylbenzene Phosphate Surface tension: 40.9 mJ / m², polar component: 1.7 mJ / m², non-polar component: 39.2 mJ / m²

[0073] (8) Interlaminar shear strength of fiber-reinforced resin substrate in integrally molded articles Using the obtained fiber-reinforced resin substrate as a bonding member, in the integrally molded product after integration with other components, the thickness of the other components on the thermoplastic resin (A) side and the thermoplastic resin (B) side of the fiber-reinforced resin substrate is 2 mm. The thickness is adjusted by methods such as cutting or grinding to produce a test plate. From the obtained test plate, as shown in Figure 1, notches with a width of 1 mm, a spacing of 6.4 mm, and a groove depth of 0~0.2 mm are formed by a cutting machine in a manner that runs parallel and alternately from both surfaces, and the front end of the notch reaches the interface between the two layers on the thermoplastic resin (A) layer side and the (B) layer side. Then, a test piece with a length of 80 mm and a width of 12.5 mm is cut out.

[0074] Compression tests were conducted using notched test specimens. The interlaminar shear strength was calculated from the obtained load and the dimensions of the test specimen. The number of tests was n=5, and the average value was taken as the interlaminar shear strength of the fiber-reinforced resin substrate in the integrally molded article.

[0075] (9) Thermal decomposition start temperature of thermoplastic resins The thermal decomposition onset temperature of thermoplastic resins was determined according to JIS K7120 (1987) using a thermogravimetric analysis (TG-DTA) apparatus in a temperature range of 50–600 °C, a heating rate of 10 °C / min, and in dry air. For this measurement, 5–15 mg of each thermoplastic resin was taken from pellets or powders used in each resin layer, or from fiber-reinforced resin substrates, and placed in a platinum container. The "onset temperature T1," where mass change begins, was taken from the obtained TG curve as the thermal decomposition onset temperature of each thermoplastic resin.

[0076] (10) Bond strength of integrally molded articles under high temperature conditions In addition to the evaluation space surrounded by a constant temperature bath, the ambient temperature was set to 150°C, and the bonding strength under high temperature conditions was evaluated using the same method as for the bonding strength of the integrally molded article described above (6). After the test piece was placed in the apparatus, a tensile test was performed 5 minutes after the ambient temperature of the constant temperature bath returned to 150°C. The bonding strength was calculated from the obtained breaking load and the area of ​​the joint. The obtained bonding strength was evaluated as follows. E was considered unacceptable. Compared with the bonding strength of (6), it shows a bonding strength of over 90%: A Compared to the bonding strength of (6), B exhibits a bonding strength of 70% or higher but less than 90%. Compared to the bonding strength of (6), the bonding strength exhibits a strength of 50% or more but less than 70%: C Compared to the bonding strength of (6), the bonding strength exhibits a strength of over 40% but less than 50%: D Compared with the bonding strength of (6), it is less than 40%: E.

[0077] <Materials used in the examples and comparative examples> The reinforcing fibers, thermoplastic resin (A), and thermoplastic resin (B) shown below were used. The materials used in each embodiment and comparative example are shown in Tables 1-3.

[0078] (1) Reinforcing fibers Acrylonitrile copolymer copolymerized with isocrine was spun and calcined to obtain carbon fibers with a total length of 24,000 filaments, a specific gravity of 1.8, and different strand strength and strand elastic modulus. CF-1: Tensile strength of strands: 5.9 GPa, elastic modulus of strands: 290 GPa. CF-2: Tensile strength of strands: 4.9 GPa, elastic modulus of strands: 230 GPa.

[0079] (2) Thermoplastic resin (A) and thermoplastic resin (B) TP-2: A thin film with a unit area weight of 120 g / m², composed of PEEK (polyetheretherketone) and PEEK 450G (manufactured by Victrex, crystalline, melting point 343℃, glass transition temperature 143℃, thermal decomposition onset temperature 480℃). TP-3: A thin film with a unit area weight of 120 g / m², composed of PPS (polyphenylene sulfide), crystallinity, melting point 284°C, glass transition temperature 90°C, and thermal decomposition start temperature 460°C. TP-5: A film with a unit area weight of 120 g / m² is made by blending modified PP and unmodified polypropylene resin (PRIME POLYMER, Inc. "Prime Polypro" (registered trademark) J105G) as 80% by mass and acid-modified polypropylene resin (Mitsui Chemicals, Inc. "Admer" QB510) as 20% by mass, and melt-blending using a biaxial extruder. TP-6: A film with a unit area weight of 120 g / m² is made by blending modified PPS, TP-3 PPS (95% by mass), and aliphatic polycarbodiimide "carbodilite (registered trademark)" (5% by mass) using a biaxial extruder for melt mixing. TP-7: A thin film with a unit area weight of 120 g / m², composed of PEKK1 (polyether ketone ketone), crystallinity, melting point 300℃, glass transition temperature 160℃, volume melt flow rate 34 cm³ / min @ 380℃, and thermal decomposition start temperature 490℃. TP-8: A thin film with a unit area weight of 120 g / m², composed of PEKK2 (polyetherketoneketone), crystallinity, melting point 332℃, glass transition temperature 162℃, volume melt flow rate 34 cm³ / min @ 380℃, and thermal decomposition onset temperature 510℃. TP-9: A thin film with a unit area weight of 120 g / m², composed of PEKK3 (polyetherketoneketone), crystallinity, melting point 332℃, glass transition temperature 162℃, volume melt flow rate 68 cm³ / min @ 380℃, and thermal decomposition onset temperature 510℃. TP-10: A thin film with a unit area weight of 120 g / m², composed of PA6 (polyamide 6), crystallinity, melting point 215°C, glass transition temperature 150°C, and thermal decomposition start temperature 330°C.

[0080] (3) Compound (a) •a-1: Sorbitol polyoxypropylene ether (EX614B, manufactured by Nagase ChemteX Co., Ltd.) •a-2: Diglyceride polyoxypropyl ether (EX421, manufactured by Nagase ChemteX Co., Ltd.) •a-3: Polyglycerol polyoxypropyl ether (EX521, manufactured by Nagase ChemteX Co., Ltd.) •a-4: Polyethylene glycol diglycidyl ether (ethylene oxide number 13, manufactured by Nagase ChemteX Co., Ltd.) ·a-5: Bisphenol A ethylene oxide 15 molar adduct.

[0081] (4) Compound (b) b-1: PO-modified polyethyleneimine (PP061, manufactured by Nippon Shokubai Co., Ltd.) b-2: Polyallylamine (PAA-01, manufactured by Nippon Shokubai Co., Ltd.) b-3: Polyethyleneimine (SP-012, manufactured by Nippon Shokubai Co., Ltd.).

[0082] (5) Compound (c) •C-1: Ethylene glycol diglycidyl ether (EX-810, manufactured by Nagase ChemteX Inc.) •C-2: Bisphenol A type diglycidyl ether (jER828, manufactured by Mitsubishi Chemical Co., Ltd.).

[0083] <Example 1> Compound a-4 was mixed with acetone to obtain a solution of approximately 1% by mass in which the compound was uniformly dissolved. Reinforcing fiber CF-1 was then impregnated in this solution and heat-treated at 210°C for 90 seconds. At this point, CF-1 was used as 100 parts by mass, and the amount of compound a-4 attached was adjusted to 0.5 parts by mass to produce continuous reinforcing fibers.

[0084] The continuous reinforcing fiber is pulled out into a unidirectionally aligned reinforcing fiber sheet (weight per unit area 193 g / m²). While advancing it in one direction, TP-8, a thermoplastic resin (B), is placed on one surface of the continuous reinforcing fiber sheet. An IR heater is used to heat the sheet, melting the thermoplastic resin (B) and adhering it to one side of the continuous reinforcing fiber sheet. Pressure is applied by three pairs of rollers at a temperature 100°C lower than the melting point of the thermoplastic resin (B) (232°C in Example 1, 100°C lower than the melting point of TP-8). This cools the sheet impregnated with the reinforcing fiber, resulting in a semi-impregnated material with the other side of the fiber-reinforced sheet exposed. TP-7, a thermoplastic resin (A), is placed on the other side of the resulting semi-impregnated material. An IR heater is used to heat the material, melting the thermoplastic resin (A) and adhering it to the surface of the semi-impregnated material. Then, pressure is applied to the thermoplastic resin (A) by three pairs of clamping rollers at a temperature 100°C lower than the melting point of the thermoplastic resin (A) (200°C in Example 1, which is 100°C lower than the melting point of TP-7), so that the thermoplastic resin (A) is impregnated in the fiber-reinforced resin intermediate, and then cooled to obtain the fiber-reinforced resin substrate.

[0085] Furthermore, the obtained fiber-reinforced resin substrate is used as a bonding member and is disposed in mold 16 as shown in FIG. 5(a). On the thermoplastic resin (A) layer side, thermoplastic resin (A) and carbon fiber (20% by mass) are melt-blended using an extruder, and the resulting carbon fiber reinforced thermoplastic resin (A) pellets 17 are injection molded. On the thermoplastic resin (B) layer side, thermoplastic resin (B) and carbon fiber (20% by mass) are melt-blended using an extruder, and the resulting carbon fiber reinforced thermoplastic resin (B) pellets 19 are injection molded to obtain an integrally molded article.

[0086] Table 1 shows the evaluation results of the obtained fiber-reinforced resin substrate and integral molded article.

[0087] <Examples 2~10> Except for the change of the compound imparted to the reinforcing fibers as described in Table 1, fiber-reinforced resin substrates were obtained using the same method as in Example 1. Table 1 shows the evaluation results of the obtained fiber-reinforced resin substrates and integrally molded articles.

[0088] Comparing Examples 1-10, the higher the surface free energy of the reinforcing fiber, the higher the interlaminar shear strength of the two resins, showing that the resulting integral molded article also has better bonding strength.

[0089] <Example 11> Except for the use of reinforcing fibers CF-2 with different strand tensile strengths as described in Table 2, fiber-reinforced resin substrates were obtained using the same method as in Example 1. Table 2 shows the evaluation results of the obtained fiber-reinforced resin substrates and integrally molded articles.

[0090] Comparing Example 1 and Example 11, it can be seen that when the tensile strength of the reinforcing fiber bundle is high, the interlaminar shear strength of the two resins is increased, and the bonding strength of the resulting integral molded article is also improved.

[0091] <Examples 12-17> Except for the change of thermoplastic resin used for thermoplastic resin (A) and / or thermoplastic resin (B) as described in Table 2, fiber-reinforced resin substrates were obtained in the same manner as in Example 1. The heating temperature of the pinch rollers was set at a temperature 100°C lower than the melting point of the thermoplastic resins used in each example. Table 2 shows the evaluation results of the obtained fiber-reinforced resin substrates and integrally molded articles.

[0092] When the combination of thermoplastic resins is changed in Examples 1 and 12-17, integral molded products with high bonding strength can also be obtained.

[0093] <Example 18> Except for using reinforcing fiber sheets with a unit area weight of 250 g / m², fiber-reinforced resin substrates were obtained in the same manner as in Example 1. Table 2 shows the evaluation results of the obtained fiber-reinforced resin substrates and integrally molded articles.

[0094] Comparing Example 1 and Example 18, the higher the volume content of the reinforcing fiber, the higher the interlaminar shear strength of the two resins, showing that the resulting integral molded article also has better bonding strength.

[0095] <Example 19> Except for the step of drawing out continuous reinforcing fibers and unidirectionally arranged reinforcing fiber sheets, in which thermoplastic resins (A) and (B) are impregnated in the unidirectionally advancing reinforcing fiber sheets, the advancing speed of the reinforcing fiber sheets is set to twice the normal speed, the fiber-reinforced resin substrate is obtained in the same manner as in Example 1. Because the advancing speed of the reinforcing fiber sheets is doubled, the impregnation time of each thermoplastic resin in the reinforcing fiber sheets is shortened. Therefore, the resulting fiber-reinforced resin substrate is in a state where each thermoplastic resin is not completely impregnated in the center of the reinforcing fiber sheets, resulting in a boundary region with voids between the opposing surfaces of each resin layer.

[0096] Next, thermoplastic resin TP-7 and carbon fiber TP-1, and thermoplastic resin TP-8 and carbon fiber TP-1 are melt-blended using an extruder to produce carbon fiber reinforced thermoplastic resin (A) pellets and (B) pellets (corresponding to carbon fiber reinforced thermoplastic resin pellets 17 and 19 in Figure 5). These carbon fiber reinforced thermoplastic resin pellets are then used for injection molding to obtain a flat plate made of carbon fiber reinforced thermoplastic resin. The flat plate obtained from the carbon fiber reinforced thermoplastic resin (A) pellets, the fiber-reinforced resin substrate obtained in Example 19, and the flat plate obtained from the carbon fiber reinforced thermoplastic resin (B) pellets are sequentially stacked and heated and pressurized in a molding machine with a hot plate temperature set to 360°C. The product is then directly cooled under pressure to obtain an integrally molded article. At this point, the thermoplastic resin (A) layer of the fiber-reinforced resin substrate is positioned in contact with the flat plate obtained from the carbon fiber reinforced thermoplastic resin (A) pellets.

[0097] The resulting monolithic product was notched, and a compression test was performed using a test piece. The results are shown in Table 3.

[0098] <Comparative Example 1> A sheet of reinforcing fiber with a unit area weight (97 g / m²) of continuously reinforcing fibers, arranged unidirectionally, is drawn out. While advancing the sheet unidirectionally, TP-7, a thermoplastic resin (A), is placed on one surface of the sheet. The thermoplastic resin (A) is melted and adhered to one side of the sheet by heating with an IR heater. Pressure is applied using rollers at a temperature 100°C lower than the melting point of thermoplastic resin (A), resulting in a fiber-reinforced resin substrate with only thermoplastic resin (A) completely impregnated in the reinforcing fiber sheet. Alternatively, a fiber-reinforced resin substrate with only thermoplastic resin (B) can be obtained by replacing TP-7 (as thermoplastic resin (A)) with TP-8 (as thermoplastic resin (B)). The two types of fiber-reinforced resin substrates obtained by lamination were heated with an IR heater to melt thermoplastic resin (B), and then pressed together with a roller at a temperature 100°C lower than the melting point of thermoplastic resin (B) to form a fiber-reinforced resin substrate. Table 3 shows the evaluation results of the obtained fiber-reinforced resin substrate.

[0099] <Comparative Example 2> Without using continuous reinforcing fibers, a laminate of thermoplastic resin film, formed by laminating TP-7 (as thermoplastic resin A) and TP-8 (as thermoplastic resin B), is heated with an IR heater to melt thermoplastic resin A, causing it to adhere to the surface of thermoplastic resin B. Then, pressure is applied using three pairs of rollers at a temperature (200°C) maintained 100°C lower than the melting point of thermoplastic resin A, resulting in a two-layer thermoplastic resin film.

[0100] Table 3 shows the evaluation results of the obtained thermoplastic resin films.

[0101] When comparing Example 1 with Comparative Examples 1 and 2, although the same type of thermoplastic resin was used, the lack of reinforcing fibers across the boundary region formed by the two thermoplastic resins resulted in the inability to exhibit high interlaminar shear strength. Furthermore, while integrally molded articles can be obtained using these resins, they do not possess sufficient bond strength.

[0102] <Comparative Example 3> Except for the thermoplastic resins used (A) and (B) as described in Table 3, fiber-reinforced resin substrates were obtained in the same manner as in Example 1. The heating temperature of the pinch rollers was set at a temperature 100°C lower than the melting point of the thermoplastic resins used. Table 3 shows the characteristics of the resulting fiber-reinforced resin substrates.

[0103] When comparing Example 1 and Comparative Example 3, since a thermoplastic resin with a melting point below 200°C was used, the bonding strength could not be maintained under high temperature conditions, and it was not suitable for use under high temperature conditions.

[0104] <Reference Example 1> Similar to Example 1, except that a fiber-reinforced resin substrate is used as the bonding component, injection molding is performed using only carbon fiber reinforced thermoplastic resin (A) pellets to produce a molded component (A) without an integral fiber-reinforced resin substrate. Next, as shown in FIG5(b), after the molded component (A) is placed in the mold 16, injection molding is performed using carbon fiber reinforced thermoplastic resin (B) pellets to produce a test piece for the bonding strength of the integrally molded article.

[0105] In Reference Example 1, although an integrally molded article can be obtained, it does not have sufficient bonding strength. The bonding strength of the integrally molded article is evaluated as D, and the bonding strength under high temperature conditions is evaluated as C.

[0106] [Table 1] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Example 9 Example 10 Fiber-reinforced resin substrate Reinforced Fibers CF-1 Tensile strength of strand 5.9 Surface free energy 20 32 twenty two 28 19 18 32 33 16 9 compound - a-4 a-1 a-2 a-3 a-5 b-1 b-2 b-3 c-1 c-2 Thermoplastic resin (A) Types of resins - TP-7 (PEKK1) Crystalline / Amorphous - Crystallinity Tm(a) / Tg(a) ℃ 300 / 160 Volumetric content Vol% 41 Thermoplastic resin (B) Types of resins - TP-8 (PEKK2) Crystalline / Amorphous - Crystallinity Tm(b) / Tg(b) ℃ 332 / 162 Volumetric content Vol% 41 Does the boundary region have reinforcing fibers? - Existing beyond the interface Tm difference ℃ 32 Roughness average length: RSm µm 30 49 37 45 29 38 53 55 27 26 Roughness average height: Rc µm 30 twenty one twenty four 29 31 28 twenty two 17 27 12 thickness mm 0.32 (A) Layer thickness ratio % 50 Interlaminar shear strength MPa 41 52 44 49 39 37 37 49 39 30 One-piece molded products Bond strength - B A B A B B A A B C Bond strength under high temperature conditions - A A A A A A A A A A

[0107] [Table 2] Example 11 Example 12 Example 13 Example 14 Example 15 Example 16 Example 17 Example 18 Example 19 Fiber-reinforced resin substrate Reinforced Fibers CF-2 CF-1 Tensile strength of strand 4.9 5.9 Surface free energy 20 20 compound - a-4 a-4 Thermoplastic resin (A) Types of resins - TP-7 (PEKK1) TP-8 (PEKK2) TP-8 (PEKK2) TP-10 (PA6) TP-10 (PA6) TP-3 (PPS) TP-3 (PPS) TP-7 (PEKK1) TP-7 (PEKK1) Crystalline / Amorphous - Crystallinity Crystallinity Crystallinity Crystallinity Crystallinity Crystallinity Crystallinity Crystallinity Crystallinity Tm(a) / Tg(a) ℃ 300 / 160 332 / 162 332 / 162 215 / 50 284 / 90 284 / 90 300 / 160 300 / 160 Volumetric content Vol% 41 41 41 38 42 42 47 41 Thermoplastic resin (B) Types of resins - TP-8 (PEKK2) TP-9 (PEKK3) TP-2 (PEEK) TP-2 (PEEK) TP-8 (PEKK2) TP-2 (PEEK) TP-8 (PEKK2) TP-8 (PEKK2) TP-8 (PEKK2) Crystalline / Amorphous - Crystallinity Crystallinity Crystallinity Crystallinity Crystallinity Crystallinity Crystallinity Crystallinity Crystallinity Tm(b) / Tg(b) ℃ 332 / 162 332 / 162 343 / 143 343 / 143 332 / 162 343 / 143 332 / 162 332 / 162 332 / 162 Volumetric content Vol% 41 41 41 41 41 41 41 47 41 Does the boundary region have reinforcing fibers? - Existing beyond the interface Crossing the boundary domain And exist Tm difference ℃ 32 0 11 128 117 59 52 32 32 Roughness average length: RSm µm 44 62 50 50 44 51 45 44 42 Roughness average height: Rc µm 14 11 15 15 13 15 14 14 18 thickness mm 0.32 0.32 0.32 0.33 0.33 0.31 0.31 0.32 0.32 (A) Layer thickness ratio % 50 50 50 52 52 49 49 50 50 Interlaminar shear strength MPa 32 38 32 33 32 32 32 38 33 One-piece molded products Bond strength - C C C C C C C A C Bond strength under high temperature conditions - A A A D D C C A A

[0108] [Table 3] Comparative Example 1 Comparative Example 2 Comparative Example 3 Fiber-reinforced resin substrate Reinforced Fibers CF-1 - CF-1 Tensile strength of strand 5.9 - 5.9 Surface free energy 20 - 20 compound - a-4 - a-4 Thermoplastic resin (A) Types of resins - TP-7 (PEKK1) TP-5 (Modified PP) Crystalline / Amorphous - Crystallinity Tm(a) / Tg(a) ℃ 300 / 160 165 / 0 Volumetric content Vol% 41 0 33 Thermoplastic resin (B) Types of resins - TP-8 (PEKK2) TP-2 (PEEK) Crystalline / Amorphous - Crystallinity Tm(b) / Tg(b) ℃ 332 / 162 343 / 143 Volumetric content Vol% 41 0 41 Does the boundary region have reinforcing fibers? - Does not exist Crossing the interface And exist Tm difference (or Tm(b)-Tg(a)) ℃ 32 168 Roughness average length: RSm µm 216 - 50 Roughness average height: Rc µm 1 - 15 thickness mm 0.32 0.19 0.36 (A) Layer thickness ratio % 50 50 56 Interlaminar shear strength MPa 17 8 31 One-piece molded products Bond strength - D D C Bond strength under high temperature conditions - B B E

[0109] 1: Fiber-reinforced resin substrate 2: Reinforced Fibers 3: Thermoplastic resin (A) layer 4: Thermoplastic resin (B) layer 5: Interface 6: Gap 7: Reinforcing fiber orientation 8: Observe the cross-section 9: Baseline 10: Vertical baseline 11: Profile Curve 12: Opposite surfaces of the thermoplastic resin (A) layer 13: Opposite surfaces of the thermoplastic resin (B) layer 14: Boundary Domain 15: Air (gap) 16: Mold 17: Carbon fiber reinforced thermoplastic resin (A) pellets 18: Injection Molding Machine 19: Carbon fiber reinforced thermoplastic resin (B) pellets 20: Carbon fiber reinforced thermoplastic resin (A) molded articles 21: Carbon fiber reinforced thermoplastic resin (B) molded articles 22: Test piece for determining the bonding strength of one-piece molded articles 23: Notched Test Piece

Claims

1. A fiber-reinforced resin substrate, comprising a continuous reinforcing fiber impregnated with thermoplastic resin (A) and thermoplastic resin (B), wherein a thermoplastic resin (A) layer composed of thermoplastic resin (A) and exposing one surface and a thermoplastic resin (B) layer composed of thermoplastic resin (B) and exposing the other surface form a boundary region, at least a portion of the aforementioned continuous reinforcing fiber exists across the aforementioned boundary region, both thermoplastic resin (A) and thermoplastic resin (B) are crystalline resins with a melting point of 200°C or higher, the difference in melting point between the aforementioned thermoplastic resin (A) and the aforementioned thermoplastic resin (B) is 10~50°C, the aforementioned continuous reinforcing fiber is a reinforcing fiber existing in the form of a fiber bundle, a laminate of fiber bundles, or a fabric, wherein the aforementioned thermoplastic resin (A) layer exposing one surface and the aforementioned thermoplastic resin (B) layer exposing the other surface form an interface and are bonded.

2. The fiber-reinforced resin substrate of claim 1, wherein the interlaminar shear strength of the aforementioned thermoplastic resin (A) layer and thermoplastic resin (B) layer, as measured by JIS K7092 (2005), is 30 MPa or more.

3. The fiber-reinforced resin substrate as requested in item 1 or 2, wherein the thermoplastic resin (A) and the thermoplastic resin (B) are different types of resin.

4. The fiber-reinforced resin substrate of claim 1 or 2, wherein the aforementioned thermoplastic resin (A) is selected from the group consisting of polyarylene ether ketone, polyphenylene sulfide, polyether ether ketone and polyether ketone ketone.

5. The fiber-reinforced resin substrate of claim 1 or 2, wherein the thickness of the aforementioned thermoplastic resin (A) layer is 20 to 80% relative to the thickness of the fiber-reinforced resin substrate.

6. The fiber-reinforced resin substrate of claim 1 or 2, wherein the volume content of the continuous reinforcing fibers in the aforementioned thermoplastic resin (A) layer and the aforementioned thermoplastic resin (B) layer is 30% by volume or more.

7. The fiber-reinforced resin substrate of claim 1 or 2, wherein the melting point of both thermoplastic resin (A) and thermoplastic resin (B) is above 250°C, and / or the glass transition temperature of both thermoplastic resin (A) and thermoplastic resin (B) is above 100°C.

8. The fiber-reinforced resin substrate of claim 1 or 2, wherein the thermal decomposition start temperature of the aforementioned thermoplastic resin (A) and the aforementioned thermoplastic resin (B) is 480°C or higher.

9. The fiber-reinforced resin substrate of claim 1 or 2, wherein the aforementioned continuous reinforcing fiber is a continuous reinforcing fiber with a surface free energy of 10 to 50 mJ / m2 as determined by the Wilhelmy method.

10. The fiber-reinforced resin substrate of claim 1 or 2, wherein the tensile strength of the aforementioned continuous reinforcing fibers is 5.5 GPa or higher.

11. The fiber-reinforced resin substrate of claim 1 or 2, wherein in a cross section cut at a 45-degree angle relative to the fiber direction of the aforementioned continuous reinforcing fibers, the average roughness length RSm of the cross section curve formed by the aforementioned interface, as defined in JIS B0601 (2001), is 100 μm or less, and the average roughness height Rc is 3.5 μm or more.

12. The fiber-reinforced resin substrate of claim 1 or 2, wherein the thickness of the aforementioned fiber-reinforced resin substrate is 500 μm or less.

13. A preform comprising a fiber-reinforced resin substrate as described in any one of claims 1 to 12, wherein a layer of thermoplastic resin (A) of a fiber-reinforced resin substrate is bonded to the thermoplastic resin (A) of component A and a layer of thermoplastic resin (B) of component B, wherein the layer of thermoplastic resin (B) of the fiber-reinforced resin substrate is bonded to the thermoplastic resin (A) of component A and the thermoplastic resin (B) of component B.

14. A one-piece molded article, wherein a component A having thermoplastic resin (A) on its surface and a component B having thermoplastic resin (B) on its surface are formed by fusing a layer of thermoplastic resin (A) of the fiber-reinforced resin substrate with the thermoplastic resin (A) of component A and a layer of thermoplastic resin (B) of component B.

15. An integrally molded article as claimed in claim 14, wherein the aforementioned component A and / or the aforementioned component B are fiber-reinforced resins.

16. A method for manufacturing a fiber-reinforced resin substrate, which is the method for manufacturing a fiber-reinforced resin substrate as claimed in any one of claims 1 to 12, characterized in that: after impregnating one side of a continuous reinforcing fiber sheet with thermoplastic resin (A) to obtain a semi-impregnated material in which one side of the thermoplastic resin (A) layer is exposed and the other side of the continuous reinforcing fiber sheet is exposed, thermoplastic resin (B) is impregnated from the other side of the semi-impregnated material; or after impregnating one side of a continuous reinforcing fiber sheet with thermoplastic resin (B) to obtain a semi-impregnated material in which one side of the thermoplastic resin (B) layer is exposed and the other side of the continuous reinforcing fiber sheet is exposed, thermoplastic resin (A) is impregnated from the other side of the semi-impregnated material.

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