Fiber-reinforced resin matrix, preform, integrated molded article, and method for manufacturing a fiber-reinforced resin matrix

Abstract

The present invention provides a fiber-reinforced resin base material in which a plurality of resins having different properties are firmly compounded. The present invention is a fiber-reinforced resin base material in which a thermoplastic resin (A) and a thermoplastic resin (B) are impregnated in continuous reinforcing fibers, wherein a layer of the thermoplastic resin (A) containing the thermoplastic resin (A) and exposed on one surface and a layer of the thermoplastic resin (B) containing the thermoplastic resin (B) and exposed on the other surface form a boundary region, at least a part of the continuous reinforcing fibers exists across the boundary region, and the thermoplastic resin (A) and the thermoplastic resin (B) are each a crystalline resin having a melting point of 200°C or higher.

Description

TECHNICAL FIELD

[0001] The present application relates to a fiber-reinforced resin base material in which a thermoplastic resin is impregnated in a reinforcing fiber, a prepreg and an integrated molded product using the same, and a method for producing the fiber-reinforced resin base material. BACKGROUND

[0002] As for a fiber-reinforced composite material using a thermosetting resin or a thermoplastic resin as a matrix, and combined with a reinforcing fiber such as carbon fiber, glass fiber, etc., it is lightweight and excellent in mechanical properties such as strength, rigidity, etc., and thus is applied to a wide range of fields such as aerospace, automobiles, railway vehicles, ships, civil engineering and construction, sports goods, etc. However, these fiber-reinforced composite materials are not suitable for manufacturing a member, a structure having a complex shape by a single molding process, and thus in the above-mentioned uses, a process of making a member formed of a fiber-reinforced composite material, and integrating it with other members is required. At this time, sometimes a resin having different properties is combined as needed. As a method of integrating a fiber-reinforced composite material with other members, a joining method of mechanical joining such as a bolt, a rivet, a screw, etc., a joining method using an adhesive can be used. In the mechanical joining method, since a process of machining a joining portion such as a hole, etc. in advance is required, it leads to a long time of a manufacturing process and an increase in manufacturing cost, and in addition, there is a problem that the material strength is reduced due to the hole. In the joining method using an adhesive, since a process of adhesion including preparation of an adhesive, an adhesive application operation, and a curing process is required, it leads to a long time of a manufacturing process, and in terms of adhesion strength, there is a problem that reliability cannot be sufficiently satisfied.

[0003] As for a fiber-reinforced composite material using a thermoplastic resin for a matrix, in addition to the above-mentioned methods, a method of joining members by a hot melt joining method can be applied, and thus it is possible to shorten the time required for joining between members. As one of the hot melt joining methods, there is a method of obtaining a molded product formed of different kinds of thermoplastic resins by two-color molding, etc., but in a case where a method of combining resins having high compatibility is selected, or a combination of resins having low compatibility, integration based on shape design such as fitting, etc. is mainstream, and there is a problem that the degree of freedom of design is low.

[0004] In this regard, Patent Literature 1 discloses a technology of joining members using different thermoplastic resins to each other by using a fiber-reinforced resin sheet in which a plurality of different thermoplastic resins are impregnated in a nonwoven fabric composed of a reinforcing fiber.

[0005] PRIOR ART DOCUMENT

[0006] PATENT LITERATURE

[0007] Patent Literature 1: International Publication No. 2014 / 103658 SUMMARY

[0008] PROBLEMS TO BE SOLVED BY THE INVENTION

[0009] However, in such a dissimilar joining, further improvement in joining strength is required. An object of the present invention is to provide a fiber-reinforced resin base material useful for firmly joining members using different thermoplastic resins, particularly dissimilar fiber-reinforced resin members using different thermoplastic resins as base resins, to each other.

[0010] MEANS FOR SOLVING THE PROBLEMS

[0011] The present invention is a fiber-reinforced resin base material in which a thermoplastic resin (A) and a thermoplastic resin (B) are impregnated in continuous reinforcing fibers, wherein a thermoplastic resin (A) layer containing the thermoplastic resin (A) and exposed on one surface and a thermoplastic resin (B) layer containing the thermoplastic resin (B) and exposed on the other surface form a boundary region, and at least a part of the continuous reinforcing fibers exists across the boundary region, and both the thermoplastic resin (A) and the thermoplastic resin (B) are crystalline resins having a melting point of 200°C or higher.

[0012] Further, another aspect of the present invention is a method for producing a fiber-reinforced resin base material in which a thermoplastic resin (A) and a thermoplastic resin (B) are impregnated in continuous reinforcing fibers, characterized in that,

[0013] after impregnating the thermoplastic resin (A) from one side of a continuous reinforcing fiber sheet to obtain a semi-impregnated preform in which a thermoplastic resin (A) layer is exposed on one side and a continuous reinforcing fiber sheet is exposed on the other side, impregnating the thermoplastic resin (B) from the other side of the semi-impregnated preform; or, after impregnating the thermoplastic resin (B) from one side of a continuous reinforcing fiber sheet to obtain a semi-impregnated preform in which a thermoplastic resin (B) layer is exposed on one side and a continuous reinforcing fiber sheet is exposed on the other side, impregnating the thermoplastic resin (A) from the other side of the semi-impregnated preform.

[0014] EFFECTS OF THE INVENTION

[0015] By using the fiber-reinforced resin base material of the present invention, an integrated molded product in which members using two kinds of thermoplastic resins are firmly joined can be produced. BRIEF DESCRIPTION OF DRAWINGS

[0016] [ Figure 1 ] Figure 1 A diagram for facilitating the explanation of a method for measuring the interlayer shear strength of a thermoplastic resin (A) layer and a thermoplastic resin (B) layer of a fiber-reinforced resin base material to which the present invention relates; the reinforcing fibers are omitted.

[0017] [ Figure 2 ] Figure 2A diagram for a fiber-reinforced resin base material related to the present application is a diagram that is useful for explaining a method for measuring the average length RSm and the average height Rc of roughness of the fiber-reinforced resin base material.

[0018] [ Figure 3 ] Figure 3 A diagram for an observation cross section perpendicular to the plane of a fiber-reinforced resin base material related to the present application is (a) an observation cross section observed in the radial direction of the reinforcing fiber, and (b) a cross section observed in the length direction of the reinforcing fiber, and is a diagram that is useful for explaining the opposite surface and the boundary region.

[0019] [ Figure 4 ] Figure 4 A diagram for an observation cross section perpendicular to the plane of a fiber-reinforced resin base material related to the present application is a diagram that is useful for explaining a method for measuring the average length RSm and the average height Rc of roughness.

[0020] [ Figure 5 ] A diagram for a method for producing a joint strength test piece of an integrally molded product related to the present application. DETAILED DESCRIPTION

[0021] Hereinafter, a fiber-reinforced resin base material related to the present application will be described. In the present specification, "~" indicates a range including both ends of the numerical value.

[0022] A fiber-reinforced resin base material related to the present application contains at least continuous reinforcing fiber, a thermoplastic resin (A), and a thermoplastic resin (B).

[0023] <Reinforcing fiber>

[0024] As the reinforcing fiber used in the present application, there are glass fiber, carbon fiber, metal fiber, aramid fiber, polyaramid fiber, alumina fiber, silicon carbide fiber, boron fiber, basalt fiber, and the like. They can be used alone or in combination of two or more as appropriate. As the reinforcing fiber, carbon fiber is preferably used because of its small specific gravity, high strength, and high elastic modulus. As commercially available products of carbon fiber, there are "Torayca (registered trademark) " T800G-24K, "Torayca (registered trademark) " T800S-24K, "Torayca (registered trademark) " T700G-24K, "Torayca (registered trademark) " T700S-24K, "Torayca (registered trademark) " T300-3K, and "Torayca (registered trademark) " T1100G-24K (all manufactured by Toray Industries, Inc.), and the like.

[0025] ​​​As the surface treatment, there are a metal adhesion treatment, a treatment using a coupling agent, a treatment using a sizing agent, an additive adhesion treatment, and the like. Note that, in the present specification, the reinforcing fiber to which a surface treatment agent is adhered is referred to as the reinforcing fiber including the surface treatment agent.

[0026] As the above-mentioned reinforcing fiber, a reinforcing fiber having a surface free energy of 10 to 50 mJ / m 2 as measured by the Wilhelmy method is preferable. By controlling to this range, the reinforcing fiber exhibits high affinity with the thermoplastic resins (A) and (B), and exhibits high joint strength in the boundary region of the thermoplastic resin (A) layer and the thermoplastic resin (B) layer across which the reinforcing fiber exists, particularly in the interface. The surface free energy of the reinforcing fiber is preferably 15 to 40 mJ / m 2 , and more preferably 18 to 35 mJ / m 2 . In the case of less than 10 mJ / m 2 , the affinity of the reinforcing fiber with the thermoplastic resin (A) or (B) becomes low, and the joint strength becomes insufficient. Further, in the case of more than 50 mJ / m 2 , the reinforcing fibers aggregate with each other, and become poorly dispersed in the fiber-reinforced resin matrix, and the variation in the joint strength becomes large.

[0027] As a method of controlling the surface free energy of the reinforcing fiber, there are a method of adjusting the amount of oxygen-containing functional groups such as carboxyl groups and hydroxyl groups by performing an oxidation treatment on the surface, and a method of adhering a single or a plurality of compounds to the surface. In the case of adhering a plurality of compounds to the surface, a compound having a high surface free energy and a compound having a low surface free energy can be mixed and adhered.

[0028] The surface free energy can be calculated from the contact angles of the reinforcing fiber with respect to three kinds of solvents (pure water, ethylene glycol, and mesityl phosphate) measured respectively, and according to the Owens approximation formula, and specifically, can be calculated by the method described in the following examples.

[0029] The fiber-reinforced resin substrate of the present invention contains reinforcing fibers in a continuous form. That is, the reinforcing fibers can exist as fiber bundles formed by long reinforcing fibers arranged unidirectionally, as laminates of fiber bundles, or as woven fabrics, and can be used in a state of being filament-blown into strips or sheets. In this specification, reinforcing fibers having these forms are collectively referred to as continuous reinforcing fibers. In the case of a reinforcing fiber bundle, it can be composed of multiple fibers of the same form, or it can be composed of multiple fibers of different forms. The number of reinforcing fibers constituting a reinforcing fiber bundle is typically 300 to 60,000, but considering the manufacture of the substrate, it is preferably 300 to 48,000, and more preferably 1,000 to 24,000.

[0030] Furthermore, when the tensile strength of the reinforcing fiber, as measured by the resin impregnation 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 can also be obtained, which is therefore preferred. A tensile strength of 5.8 GPa or higher is even more preferred.

[0031] The fiber-reinforced resin substrate of the present invention has a reinforcing fiber content of 30 g / m² per unit area. 2 This is preferred. If the amount of reinforcing fiber is 30 g / m² 2 This allows for a more robust composite of the thermoplastic resin layers (A) and (B), facilitating subsequent processing for obtaining preforms and integrated molded products. There is no specific upper limit for the amount of reinforcing fibers, but a value of 2,000 g / m² is acceptable. 2 The following allows thermoplastic resins (A) and (B) to be easily impregnated into the reinforcing fibers while maintaining the lightweight nature of the fiber-reinforced resin matrix.

[0032] 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. When the volume fraction of reinforcing fibers is 30% by volume or more, the amount of resin does not become excessive compared to the amount of fiber, making it easy to obtain a fiber-reinforced resin substrate with excellent specific strength and specific modulus of elasticity. When the volume fraction of reinforcing fibers is 90% by volume or less, poor resin impregnation is less likely to occur, the formation of pores can be suppressed, and a fiber-reinforced resin substrate in which the thermoplastic resin (A) layer and the (B) layer are firmly 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.

[0033] <Thermoplastic Resin (A) and Thermoplastic Resin (B)>

[0034] The thermoplastic resin (A) and the thermoplastic resin (B) of the present application are a combination of "different thermoplastic resins". The term "different" herein means that the thermoplastic resin (A) and the thermoplastic resin (B) are not the same thermoplastic resin, i.e., the case where the same thermoplastic resin having the same composition and the same viscosity and melting point is used as the thermoplastic resin (A) and the thermoplastic resin (B), i.e., the case where the same thermoplastic resin is simply layered as the fiber-reinforced resin substrate. The thermoplastic resin (A) and the thermoplastic resin (B) are not particularly limited as long as they are not the same thermoplastic resin. More specifically, the term "different" means that a commercially available thermoplastic resin of one grade is used as the thermoplastic resin (A) and the thermoplastic resin (B). In the present specification, the term "thermoplastic resin" alone means the concept including both the thermoplastic resin (A) and the thermoplastic resin (B).

[0035] For example, even if the resins have the same composition, i.e., the same repeating unit, the resins having different viscosity and melting point can be said to be different thermoplastic resins. In this case, if the resins having the same composition are produced by the same production method, the resins can be said to be the same even if the viscosity and the melting point are extremely slightly different due to variations in the production conditions. In addition, even if both are polyamides, nylon 6 and nylon 66 are different resins.

[0036] Note that the effect of the present application becomes greater when the thermoplastic resin (A) and the thermoplastic resin (B) are different resin types. The similarity or difference in the resin types is determined by the identity of the structure that characterizes the thermoplastic resin. For example, if the resin is a polyamide resin, it is a resin having a repeating unit including an amide bond, and if the resin is a polyester resin, it is a resin having a repeating unit including an ester bond. Since these are resins having repeating units with different bonds, they are determined to be different resin types.

[0037] As the thermoplastic resin, generally, a thermoplastic resin having a bond selected from the group consisting of carbon-carbon bond, amide bond, imide bond, ester bond, ether bond, carbonate bond, urethane bond, sulfide bond, sulfone bond, and carbonyl bond in the main chain can be preferably used. It is also not problematic that the thermoplastic resin partially has a crosslinked structure. In particular, it is appropriate that at least one resin selected from the group consisting of polyamide, polyacetal, polyphenylene sulfide, polyester, polyether ketone, polyether ether ketone, polyarylene ether ketone, polyaramide, and polyether nitrile.

[0038] In addition, the thermoplastic resin can be a copolymer, a modified product, and / or a resin obtained by blending two or more resins, and the like. In the case where a resin obtained by blending two or more resins is used, the resin that accounts for the largest amount of the resins constituting each thermoplastic resin is the thermoplastic resin. If the resin that accounts for the largest amount of the resins in each of the thermoplastic resin (A) and the thermoplastic resin (B) is different, the resin types of the two are determined to be different.

[0039] In the present application, it is preferable that the difference between the melting points of the thermoplastic resin (A) and the thermoplastic resin (B) is 10 to 50°C. Herein, in the present specification, the "melting point" and the "glass transition temperature" can be measured based on JIS K7121 (2012) using a differential scanning calorimeter (DSC). In a closed sample container with a volume of 50 μl, 1 to 10 mg of a sample is loaded, and the temperature is increased at a rate of 10°C / minute, and the step difference of the DSC curve detected in the range of 30 to 400°C is used as an index of the glass transition temperature, and the heat generation peak is used as an index of the melting point, and the respective temperatures are used as the glass transition temperature and the melting point.

[0040] Hereinafter, for convenience, the case where the resin having a high melting point is used as the thermoplastic resin (B) in such a manner is described. At this time, it is preferable that the melting point of the thermoplastic resin (B) is higher than the melting point of the thermoplastic resin (A) by 30°C or more. In the case where the difference between the melting points is less than 10°C, under the temperature conditions for melting only the thermoplastic resin (A) layer for joining with other members, the thermoplastic resin (B) layer also melts or thermally deforms, and the reduction in the mechanical properties of the molded article caused by the deformation of the shape of the fiber-reinforced resin base material, the reduction in the joining strength caused by the disorder of the reinforcing fibers of the fiber-reinforced resin base material, and the change in the interface state occur. From the viewpoint of improving the design freedom of the combination of the resins, the temperature conditions at the time of joining, and the like, it is preferable that the melting point of the thermoplastic resin (B) is higher than the melting point of the thermoplastic resin (A) by 40°C or more, and it is further preferable that it is higher by 45°C or more. If the difference between the melting points of the aforementioned thermoplastic resin (A) and the aforementioned thermoplastic resin (B) is 50°C or less, the thermal decomposition of the other thermoplastic resin can be suppressed under the temperature conditions for melting one of them.

[0041] It is preferable that the thermoplastic resin (A) is a resin selected from the group consisting of polyarylene ether ketone, polyphenylene sulfide, polyether ether ketone, and polyether ketone ketone, and it is preferable that the thermoplastic resin (B) also adopts a resin selected from the aforementioned group. By selecting the aforementioned thermoplastic resin, a fiber-reinforced resin base material which can maintain heat resistance and high mechanical properties under a high-temperature high-humidity environment can be produced. In addition, polyarylene ether ketone is excellent in chemical resistance and abrasion resistance, and polyphenylene sulfide is excellent in chemical resistance, and thus the characteristics can be compensated by being combined with other thermoplastic resins which are poor in chemical resistance and abrasion resistance.

[0042] By combining resins having different characteristics such as a difference in melting point, a difference in viscosity, and a difference in resin type, rather than the same resin, it is possible to apply the fiber-reinforced thermoplastic resin to uses and positions that have been difficult to apply in the past. In the case of combining resins having a difference in melting point and a difference in resin type, by arranging a resin having a low melting point on the resin layer side to be joined to another member, it is possible to melt only the resin layer to be joined and maintain the appearance of the resin layer on the opposite side. In the case of combining resins having a difference in viscosity and a difference in resin type, by using a resin having a low viscosity and a resin type, it is possible to shorten the impregnation time of the reinforcing fiber, and thus it is possible to achieve a reduction in the production process time of the fiber-reinforced resin base material. The fiber-reinforced resin base material combining resins having these different characteristics and resin types is particularly preferably applied to positions that are boundaries of the environment and the use conditions, and for example, it can be effectively used for: positions in a pipe or the like cylindrical body, a container, or the like, in which the inside is exposed to oil, chemicals, steam in a high-temperature and high-humidity environment, or the like; positions in a refrigerator, an oven, or the like, which are boundaries of the use temperature and require thermal insulation; and the like.

[0043] From the viewpoint of good heat resistance and not easily causing heat distortion, it is preferable that the glass transition temperature of the thermoplastic resins (A) and (B) of the present application each be 100°C or higher, more preferable 150°C or higher, and further preferable 180°C or higher. As the crystalline thermoplastic resin having a glass transition temperature of 100°C or higher, there can be mentioned polyketone, polyether ketone, polyether ether ketone, polyether ketone ketone, and the like polyarylene ether ketone, alicyclic polyamide, semi-aromatic polyamide, polyphenylene sulfide, and the like.

[0044] From the viewpoint of good heat resistance, it is preferable that the thermoplastic resins (A) and (B) each be a crystalline resin having a melting point of 200°C or higher. If it is a crystalline resin, the mechanical mechanical properties are also high, and it is possible to use continuously for a long time even in a high-temperature environment required for an aircraft use or the like. Among them, it is preferable that the melting point of the thermoplastic resins (A) and (B) each be 250°C or higher, more preferable 300°C or higher, and further preferable 350°C or higher. There is no particular limitation on the upper limit of the melting point, and the upper limit of a general thermoplastic resin is 400°C.

[0045] From the viewpoint of suppressing heating at the time of integration with another member, heat resistance at the time of use as an integrated molded product, and suppressing a reduction in physical properties in a high-temperature environment, it is preferable that the thermoplastic resins (A) and (B) of the present application each have a thermal decomposition initiation temperature of 480°C or higher, more preferable 500°C or higher, and further preferable 550°C or higher.

[0046] To improve the impact resistance, an elastomer or a rubber component can also be added to the thermoplastic resin. Furthermore, other filler materials, additives can also be appropriately contained within a range not impairing the object of the present application depending on the use or the like. For example, inorganic filler materials, flame retardants, electric conductivity imparting agents, nucleating agents, ultraviolet absorbers, antioxidants, vibration dampers, antibacterial agents, insect repellents, deodorants, coloration preventing agents, heat stabilizers, release agents, antistatic agents, plasticizers, lubricants, colorants, pigments, dyes, foaming agents, antifoaming agents, coupling agents, and the like can be cited.

[0047] The unit area weight of each of the thermoplastic resins (A) and (B) forming each layer in the fiber-reinforced resin substrate of the present application is 10 g / m 2 The above is preferable. The unit area weight of each resin is 10 g / m 2 In the above, the boundary region of the thermoplastic resin (A) layer and the (B) layer, particularly the interface where the thermoplastic resin (A) layer and the (B) layer meet, can be made to have a sufficient thickness for exhibiting excellent joint strength, which is preferable. Furthermore, a sufficient layer thickness for integration with other members can be obtained. More preferably, it is 20 g / m 2 In the above, further preferably, it is 50 g / m 2 In the above. The upper limit value is not particularly limited, and preferably, it is 1000 g / m 2 Hereinafter, this is because the amount of the thermoplastic resin does not become excessive compared to the reinforcing fiber, and a fiber-reinforced resin substrate excellent in specific strength and specific elastic modulus can be obtained. Here, the unit area weight means the mass (g) of the thermoplastic resin contained per 1 m 2 of the fiber-reinforced resin substrate.

[0048] < FIBER-REINFORCED RESIN SUBSTRATE >

[0049] In the fiber-reinforced resin substrate of the present application, a thermoplastic resin (A) and a thermoplastic resin (B) different from the thermoplastic resin (A) are impregnated in continuous reinforcing fibers, and a thermoplastic resin (A) layer containing the thermoplastic resin (A) is exposed on one surface, and a thermoplastic resin (B) layer containing the 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.

[0050] Furthermore, at least a part of the aforementioned continuous reinforcing fibers exists across the boundary region of the thermoplastic resin (A) layer and the thermoplastic resin (B) layer. Here, the "boundary region" as shown in Figure 3 means the opposite surface 12 of the thermoplastic resin (A) layer 3 in the fiber-reinforced substrate 1, which is opposite to the surface, and the surface opposite to the surface of the thermoplastic resin (B) layer 4, that is, Figure 3 Figure 3 ​the region of the opposite surface 13 of the thermoplastic resin (B) layer and the air (void) 15 therebetween. The opposite surface is a surface at which the resin layer is in contact with the opposite surface of the other resin or the air (void).

[0051] Using Figure 3 (a) and (b) to show "existing across the boundary region". In Figure 3 (b), the reinforcing fiber 2 (illustrated with dotted lines) exists in either of the thermoplastic resin (A) layer 3 and the thermoplastic resin (B) layer 4, that is, the reinforcing fiber 2 exists across the boundary region 14 existing between the resin layers. By making the reinforcing fiber 2 exist across the boundary region 14, the thermoplastic resin (A) layer 3 and the thermoplastic resin (B) layer 4 are physically joined via the reinforcing fiber 2.

[0052] In which, as shown in Figure 4 , it is preferable that the thermoplastic resin (A) layer 3 and the thermoplastic resin (B) layer 4 are joined by forming an interface 5, because the thermoplastic resins are chemically and / or physically bonded to each other. Here, by "joined by forming an interface", it means a state in which the thermoplastic resin (A) layer 3 and the thermoplastic resin (B) layer 4 are in contact to form the boundary region 14 without containing air (void), and the opposite surfaces of the respective resin layers, that is, the opposite surface 12 of the thermoplastic resin (A) layer and the opposite surface 13 of the thermoplastic resin (B) layer, are in close contact with each other.

[0053] Using Figure 4 to show "joined by forming an interface". In Figure 4 the observed image 8, the thermoplastic resin (A) layer 3 containing the thermoplastic resin (A) and the thermoplastic resin (B) layer 4 are joined by forming an interface 5. And, there are a plurality of continuous reinforcing fibers 2 existing on the interface 5. Such a state in which the thermoplastic resin (A) layer 3 and the thermoplastic resin (B) layer 4 are in contact with the surroundings of the reinforcing fibers can be said to be a state in which the reinforcing fibers "exist across the interface".

[0054] By having the continuous reinforcing fiber exist in both resin layers in a cross-boundary fashion, the joining strength of the thermoplastic resin layers to each other is improved. By having the continuous reinforcing fiber existing on the interface chemically or / and physically bond with the thermoplastic resin (A) and the thermoplastic resin (B), the adhesion of the thermoplastic resin (A) layer to the thermoplastic resin (B) layer is improved. If the number of the continuous reinforcing fibers existing on the interface is 4 or more in the observation range of 500 μm x 500 μm described later, it is preferable from the viewpoint of exhibiting firm joining of the thermoplastic resin (A) layer to the thermoplastic resin (B) layer, more preferably 10 or more, and further preferably 30 or more. The upper limit of the number is not particularly limited, and it is preferable to be 200 or less from the viewpoint of exhibiting firm joining strength and suppressing excessive orientation of the reinforcing fiber, and obtaining a fiber-reinforced resin substrate having a good appearance.

[0055] In the fiber-reinforced resin substrate of the present application, the interlaminar shear strength of the aforementioned thermoplastic resin (A) layer to the thermoplastic resin (B) layer measured by JIS K7092 (2005) is preferably 30 MPa or more. By having such an interlaminar shear strength, an integrated molded product in which members containing different thermoplastic resins are firmly joined to each other can be obtained. The interlaminar shear strength is more preferably 40 MPa or more, and further preferably 50 MPa or more. The upper limit of the interlaminar shear strength is not particularly limited, and 100 MPa or less is sufficient. The interlaminar shear strength can be measured using, for example, a cross-cut test piece 23 shown in FIG. 6 in which a cross-cut 6 reaching the interface 5 of the fiber-reinforced resin substrate 1 is formed, and by the method described in the Examples described later. Figure 1

[0056] In the fiber-reinforced resin substrate of the present application, in a cross section obtained by cutting the fiber-reinforced resin substrate vertically to the fiber-reinforced resin substrate plane direction in the 45-degree direction with respect to the fiber direction (both clockwise and counterclockwise) of an arbitrary continuous reinforcing fiber from the top view of the fiber-reinforced resin substrate, i.e., a cross section perpendicular to the fiber-reinforced resin substrate plane containing the aforementioned continuous reinforcing fiber, by observing the morphology of the resin layer in the interface, the adhesion in the fiber axial direction and the direction orthogonal thereto can be evaluated at the same time.

[0057] ​In the fiber-reinforced resin substrate of the present application, it is preferable that the roughness average length RSm of the cross-sectional profile formed at the interface of the two resin layers be 100 μm or less and the roughness average height Rc be 3.5 μm or more as defined by JIS B0601 (2001). If RSm is 100 μm or less, not only chemical and / or physical bonding force but also mechanical bonding force due to mutual penetration of the respective resin layers is added, and the thermoplastic resin (A) layer and the thermoplastic resin (B) layer become less likely to peel. The lower limit of RSm is not particularly limited, and it is preferable to be 15 μm or more from the viewpoint of avoiding reduction in mechanical bonding force due to stress concentration. Further, by making Rc of the cross-sectional profile 3.5 μm or more, not only mechanical bonding force based on entanglement but also chemical and / or physical bonding of the continuous reinforcing fibers present at the interface with the thermoplastic resin (A) and the thermoplastic resin (B) is present, and thus the adhesion of the thermoplastic resin (A) layer and the thermoplastic resin (B) layer is improved. As a preferable range of Rc, it is 10 μm or more, and particularly preferably 20 μm or more, so that the continuous reinforcing fibers become more likely to be contained in the two resin layers and the adhesion is further improved. The upper limit of Rc is not particularly limited, and it is preferable to be 100 μm or less from the viewpoint of avoiding reduction in mechanical bonding force due to stress concentration.

[0058] Here, as a method for measuring the roughness average height Rc and the roughness average length RSm of the cross-sectional profile, known methods can be used. For example, methods in which cross-sectional images obtained using X-ray CT are measured, methods in which element analysis distribution images obtained using an energy dispersion type X-ray spectrometer (EDS) are measured, or methods in which cross-sectional observation images obtained using an optical microscope or a scanning electron microscope (SEM) or a transmission electron microscope (TEM) are measured can be given. In the observation, in order to adjust the contrast, the thermoplastic resin (A) and / or the thermoplastic resin (B) can be dyed. In the images obtained using any of the above methods, the roughness average height Rc and the roughness average length RSm of the cross-sectional profile are measured in a range of 500 μm x 500 μm. The calculation of Rc and RSm from the cross-sectional observation images can be performed by the method described in the Examples below.

[0059] As a method for making the roughness average height Rc and the roughness average length RSm of the cross-sectional profile of the present application be within the preferable range, operations such as increasing the time for which pressure is applied by increasing the nip roller or the like through which pressure is applied, lowering the viscosity of the thermoplastic resin by setting the surface temperature of the member on which the nip roller or the like is heated and pressurized to be high, and the like in the step of impregnating the thermoplastic resin into the continuous reinforcing fibers can be given.

[0060] From the viewpoint of handling properties and exhibiting a strong joining strength when used in the joining of a plurality of members, the thickness of the fiber-reinforced resin base material of the present application is preferably 500 μm or less, more preferably 400 μm or less, and further preferably 300 μm or less. The lower limit of the thickness is not particularly limited, and if it is 20 μm or more, handling is good, which is preferable.

[0061] With respect to the thickness of the thermoplastic resin (A) layer in the fiber-reinforced resin base material, it is preferably 20 to 80% relative to the thickness of the fiber-reinforced resin base material. From the viewpoint of suppressing warping, the thickness can also be adjusted in relation to the molding shrinkage of the resin used. Furthermore, since melting is easy in the case of a thin thickness, the proportion of the thickness of the resin layer that is desired to be melted in a short time can be reduced, the thickness can be increased in order to not easily melt, and the like.

[0062] <Preform>

[0063] The fiber-reinforced resin base material of the present application can be laminated with a metal member, a fiber-reinforced thermoset resin member in which a thermoset resin is used in the base resin, a fiber-reinforced thermoplastic resin member in which a thermoplastic resin is used in the base resin, and the like to produce a preform. In particular, in the case where a member A having a thermoplastic resin (A) on the surface is joined to a member B having a thermoplastic resin (B) on the surface, by producing a preform in which the fiber-reinforced resin base material of the present application is disposed between these members so that the thermoplastic resin (A) layer of the fiber-reinforced resin base material is in contact with the thermoplastic resin (A) of the member A and the thermoplastic resin (B) layer is in contact with the thermoplastic resin (B) of the member B, the effects of the present application can be exhibited to the greatest extent.

[0064] <One-piece molded product>

[0065] Furthermore, a plurality of members can be joined via the fiber-reinforced resin base material of the present application to produce a one-piece molded product. Typically, such a one-piece molded product can be obtained by heating and pressurizing the aforementioned preform using the molding method described later.

[0066] Among them, the following integrally molded product, which is formed by melting and joining the thermoplastic resin (A) layer of the fiber-reinforced resin base material and the thermoplastic resin (A) of the member A, and the thermoplastic resin (B) layer and the thermoplastic resin (B) of the member B via the fiber-reinforced resin base material, can exhibit the effects of the present application to the greatest extent. In a preferred mode, one of the member (A) and the member (B) is a fiber-reinforced resin or both are fiber-reinforced resins, in which case a molded product having excellent strength can be obtained as a whole. At this time, from the viewpoint of suppressing thermal decomposition of the thermoplastic resin, a method in which one of the fiber-reinforced resin base material and the member A or the member B is joined, and the other member is sequentially integrated, or a method in which the aforementioned prepreg having the fiber-reinforced resin base material disposed between the member A and the member B is heated and pressurized and integrated at the same time, can be used. At this time, in the fiber-reinforced resin base material, each resin can be further impregnated into the inside of the continuous reinforcing fiber to form an interface.

[0067] As the molding method of the integrally molded product of the present application, for example, hot melting, vibration melting, ultrasonic melting, laser melting, resistance melting, induction melting, insert injection molding, over-molding, two-color molding, press molding method, autoclave molding method, bag molding method, tape winding method, internal pressure molding method, hand lay-up molding method, filament winding method, pultrusion molding method, resin injection molding method, resin transfer molding method, and the like can be given.

[0068] <Method for producing fiber-reinforced resin base material>

[0069] As an example of the fiber-reinforced resin base material of the present application, it can be produced by a method in which the thermoplastic resin (A) is impregnated from one side of a continuous reinforcing fiber sheet to obtain a semi-impregnated blank in which the thermoplastic resin (A) layer is exposed on one side and the continuous reinforcing fiber sheet is exposed on the other side, and then the thermoplastic resin (B) is impregnated from the aforementioned other side of the semi-impregnated blank, or a method in which the thermoplastic resin (B) is impregnated from one side of a continuous reinforcing fiber sheet to obtain a semi-impregnated blank in which the thermoplastic resin (B) layer is exposed on one side and the continuous reinforcing fiber sheet is exposed on the other side, and then the thermoplastic resin (A) is impregnated from the aforementioned other side of the semi-impregnated blank. At this time, as described above, if the case where the thermoplastic resin (B) has a higher melting point than the thermoplastic resin (A) is described, by impregnating the thermoplastic resin (B) having a high melting point first, the possibility of thermal decomposition and thermal deterioration of the thermoplastic resin (B) due to the heating temperature applied to the thermoplastic resin (A) for the subsequent impregnation can be reduced, and thus this is preferred.

[0070] As the method of impregnating the thermoplastic resin from one side, the thermoplastic resin can be impregnated by a method of disposing the thermoplastic resin in the form of a film, nonwoven fabric, or particles on the surface of the continuous reinforcing fiber sheet and performing heating and pressurization, or a method of applying the thermoplastic resin in a molten state or a liquid state dissolved in a solvent to the surface of the continuous reinforcing fiber sheet and performing heating and pressurization to impregnate it. As the method of heating, known methods can be used. For example, noncontact heating methods using a far infrared heater, a high-temperature oven, or induction heating, methods of heating by contact with a heated roll or belt, and the like can be given. Among these, a method of heating by passing from a slot of a far infrared heater or a high-temperature oven is preferable from the viewpoint of temperature control. The method of pressurization is not particularly limited, and methods of pressurization by a reverse roll, a forward roll, a kiss roll, an applicator, or a belt, and the like can be given. Note that in the case where the viscosity of the molten thermoplastic resin is low, pressurization can not necessarily be required. Further, a method of impregnating the thermoplastic resin by depressurizing from the side opposite to the surface on which the thermoplastic resin is disposed or applied can also be given.

[0071] As the method of impregnating the thermoplastic resin from the other side, the same methods as those of impregnating the thermoplastic resin from the aforementioned one side can be used. From the viewpoint of suppressing thermal decomposition and thermal deterioration of the thermoplastic resin that is impregnated first, the temperature at which the thermoplastic resin that is impregnated from the other side is melted and dissolved, the disposition of a heat source only on the other side, and the like can be arbitrarily adjusted.

[0072] Examples

[0073] Hereinafter, the present application will be described in detail using examples. However, the scope of the present application is not limited to these examples. Note that, as for the unit of the composition ratio "parts", "parts by mass" is meant unless otherwise noted. Further, as for the measurement of various properties, the measurement was performed in an environment at a temperature of 23°C and a relative humidity of 50% unless otherwise noted.

[0074]

[0075] (1) Interlaminar shear strength of fiber-reinforced resin substrate

[0076] ​The interlaminar shear strength of the thermoplastic resin (A) layer and the thermoplastic resin (B) layer of the fiber-reinforced resin substrate was measured based on JIS K7092 (2005). In the fiber-reinforced resin substrate of the present application and the comparative examples, the length direction of the test piece was set to the same direction as the fiber direction of the continuous reinforcing fibers. After a prepreg containing carbon fibers and an epoxy resin was stacked so as to have a thickness of 2 mm, a cured plate was obtained by press molding. The surface of the obtained cured plate was roughened by a sandblasting machine, and was subjected to debinding. An acrylic adhesive was applied to the surface of the cured plate, and was attached to both surfaces of the fiber-reinforced resin substrate, and the adhesive was cured to produce a test plate for measurement. With respect to the obtained test plate, as shown in FIG. 1, a notch having a width of 1 mm, a pitch of 6.4 mm, and a difference depth of 0 to 0.2 mm was formed in parallel and staggered from both surfaces, and so as to reach the interface between the two layers at the leading end of the notch on the thermoplastic resin (A) layer side and the (B) layer side, using a cutting machine. Thereafter, a test piece having a length of 80 mm and a width of 12.5 mm was cut out. Figure 1

[0077] The interlaminar shear strength of the thermoplastic resin (A) layer and the thermoplastic resin (B) layer of the fiber-reinforced resin substrate was measured based on JIS K7092 (2005). In the fiber-reinforced resin substrate of the present application and the comparative examples, the length direction of the test piece was set to the same direction as the fiber direction of the continuous reinforcing fibers. After a prepreg containing carbon fibers and an epoxy resin was stacked so as to have a thickness of 2 mm, a cured plate was obtained by press molding. The surface of the obtained cured plate was roughened by a sandblasting machine, and was subjected to debinding. An acrylic adhesive was applied to the surface of the cured plate, and was attached to both surfaces of the fiber-reinforced resin substrate, and the adhesive was cured to produce a test plate for measurement. With respect to the obtained test plate, as shown in FIG. 1, a notch having a width of 1 mm, a pitch of 6.4 mm, and a difference depth of 0 to 0.2 mm was formed in parallel and staggered from both surfaces, and so as to reach the interface between the two layers at the leading end of the notch on the thermoplastic resin (A) layer side and the (B) layer side, using a cutting machine. Thereafter, a test piece having a length of 80 mm and a width of 12.5 mm was cut out.

[0078] (2) Melting point and glass transition temperature of thermoplastic resin

[0079] The melting point and the glass transition temperature of the thermoplastic resin were measured based on JIS K7121 (2012) using a differential scanning calorimeter (DSC). A sample of 1 to 10 mg was charged in a sealed sample container having a volume of 50 μl, and was subjected to temperature elevation at a rate of 10°C / min, and the step difference of the DSC curve detected in the range of 30 to 400°C was taken as an index of the glass transition temperature, and the heat generation peak was taken as an index of the melting point, and the respective temperatures were taken as the glass transition temperature and the melting point.

[0080] (3) Roughness average length RSm and roughness average height Rc of fiber-reinforced resin substrate

[0081] The fiber-reinforced resin substrate produced was cut at an angle of 45 degrees to the plane of the fiber-reinforced resin substrate with respect to the fiber direction 7 of the reinforcing fibers 2 contained in the two resin layers, perpendicularly to the plane direction of the fiber-reinforced resin substrate, as shown in FIG. 2, to obtain a test piece having an observation cross section 8. The obtained test piece was embedded with an epoxy resin, and the observation cross section was polished. In the obtained observation cross section, 10 images at 1000 times were taken using an optical microscope. Figure 2

[0082] ​​The case of any 500μm × 500μm observation area in the obtained image is as follows: Figure 4 As shown in the schematic diagram. In this observation screen 8, an interface 5 is formed between thermoplastic resin (A) layer 3 and thermoplastic resin (B) layer 4. Here, the end of thermoplastic resin (B) layer 4 containing thermoplastic resin (B) is used as the reference line 9, and vertical baselines 10 are drawn from thermoplastic resin (B) layer 4 containing thermoplastic resin (B) towards thermoplastic resin (A) layer 3 containing thermoplastic resin (A) at 5 μm intervals. The point where the vertical baseline 10 drawn from the reference line 9 first intersects with thermoplastic resin (A) layer 3 is marked, and the line connecting the marked points is used as the cross-sectional curve 11. The obtained cross-sectional curve 11 is subjected to screening based on JIS B0601 (2001), and the average roughness height Rc and average roughness length RSm of the cross-sectional curve 11 are calculated. The average roughness height Rc and average roughness length RSm are similarly calculated from the obtained 10 images, and the average value is used as each value.

[0083] (4) Volume content of reinforcing fibers in thermoplastic resin (A) layer and (B) layer

[0084] A sample was prepared by cutting 20mm square pieces from a fiber-reinforced resin substrate, embedding them in epoxy resin, and then grinding them with the cross-section perpendicular to the fiber direction of the reinforcing fibers of the fiber-reinforced resin substrate as the observation surface. The sample was magnified 400x using a laser microscope (Keyence Corporation, VK-9510) to observe the cross-section. The observed image was unfolded on general image analysis software, and the cross-section of the reinforcing fibers visible in the observed image was extracted using a program programmed 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). The proportion of the total reinforcing fiber area per unit area of ​​the thermoplastic resin (A) layer was calculated from the measured area. The same measurement was performed at 5 observation surfaces, and the average value was taken as the volume content of the reinforcing fibers in the thermoplastic resin (A) layer of the present invention. Furthermore, the same method was used to measure the thermoplastic resin (B) layer.

[0085] (5) The ratio of the thickness of the thermoplastic resin (A) layer to the thickness of the fiber-reinforced resin substrate.

[0086] The average value of the plotted 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 measured and taken as the thickness of the thermoplastic resin (A) layer. In addition, the thickness of the fiber-reinforced resin substrate is measured using a micrometer, and the thickness ratio is calculated from these measurements.

[0087] (6) Bond strength of integrally molded parts

[0088] The obtained fiber-reinforced resin substrate is used as a bonding component, such as Figure 5 As shown in (a), the arrangement is in the mold 12. On the thermoplastic resin (A) layer side, carbon fiber reinforced thermoplastic resin (A) granules 17, which are produced by melt-blending thermoplastic resin (A) and carbon fiber (20% by mass) using an extruder, are injection molded. On the thermoplastic resin (B) layer side, carbon fiber reinforced thermoplastic resin (B) granules 19, which are produced by melt-blending thermoplastic resin (B) and carbon fiber (20% by mass) using an extruder, are injection molded to produce a test piece 21 for measuring the bonding strength of the integrally molded article.

[0089] 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.

[0090] A. Fracture of the base material of the injection-molded part exceeding 50 MPa:

[0091] 40MPa or higher but less than 50MPa, or fracture of the base material of the injection-molded part: B

[0092] 30MPa or higher but less than 40MPa, or fracture of the base material of the injection-molded part: C

[0093] Less than 30MPa: D (Unqualified).

[0094] (7) Enhance the surface free energy of fibers

[0095] Using a DCAT 11 manufactured by DataPhysics, first, one single fiber was taken out from the reinforcing fiber bundle, cut into 8 pieces of 12 ± 2 mm in length, and then attached to a special holder FH12 (a flat plate coated with an adhesive substance) in parallel with 2 to 3 mm between the single fibers. Thereafter, the front ends of the single fibers were cut flush and set in the DCAT 11 of the holder. The measurement was performed as follows: a tank containing each solvent was brought close to the lower ends of the 8 single fibers at a speed of 0.2 mm / s, and immersed to 5 mm from the front ends of the single fibers. Thereafter, the single fibers were pulled up at a speed of 0.2 mm / s. This operation was repeated 4 times or more. The force F received by the single fibers when immersed in the liquid was measured with an electronic balance. This value was used to calculate the contact angle θ according to the following equation.

[0096] COS θ = (the force F (mN) received by the 8 single fibers) / ((8 (the number of single fibers) x the circumference (m) of the single fiber x the surface tension (mJ / m2) of the solvent) 2 )

[0097] Note that the measurement was performed on single fibers taken out from different positions of the reinforcing fiber bundle of 3. That is, the average of the contact angles of a total of 24 single fibers was calculated for one reinforcing fiber bundle.

[0098] The surface free energy γ of the reinforcing fiber f The polar component γp of the surface free energy p f , and the apolar component γa of the surface free energy d f were calculated as the sum of the squares of the slope a and the intercept b when the components of the surface tension and the contact angle of each liquid were plotted on X and Y, and then a straight line was fitted by the least square method.

[0099] The polar component γp of the surface free energy p f was calculated as the square of the slope a, and the apolar component γa of the surface free energy d f was calculated as the square of the intercept b. The surface free energy γ of the reinforcing fiber f was the sum of the square of the slope a and the square of the intercept b.

[0100] Y = a • X + b

[0101] X = √(the polar component (mJ / m2) of the surface tension of the solvent) / √(the apolar component (mJ / m2) of the surface tension of the solvent) 2 2

[0102] ​​Y = (1 + COS θ) • (polar component of surface tension of solvent (mJ / m 2 )) / 2√(apolar component of surface tension of solvent (mJ / m 2 )

[0103] Polar component of surface free energy of reinforcing fiber γ p f = a 2

[0104] Apolar component of surface free energy of reinforcing fiber γ d f = b 2

[0105] Total surface free energy γ f = a 2 + b 2 .

[0106] The polar and apolar components of the surface tension of each solvent are as described below.

[0107] • Purified water

[0108] Surface tension 72.8 mJ / m 2 , polar component 51.0 mJ / m 2 , apolar component 21.8 mJ / m 2

[0109] • Ethylene glycol

[0110] Surface tension 48.0 mJ / m 2 , polar component 19.0 mJ / m 2 , apolar component 29.0 mJ / m 2

[0111] • Triphenyl phosphate

[0112] Surface tension 40.9 mJ / m 2 , polar component 1.7 mJ / m 2 , apolar component 39.2 mJ / m 2 .

[0113] (8) Interlaminar shear strength of fiber-reinforced resin substrate in integrally molded product

[0114] In an integrally molded product in which the obtained fiber-reinforced resin substrate is integrated with other components as a joint component, a test plate was prepared by adjusting the thickness in such a manner that the thickness of the other components on the thermoplastic resin (A) side and the thermoplastic resin (B) side of the fiber-reinforced resin substrate becomes 2 mm by cutting, polishing, or the like. With respect to the obtained test plate, as Figure 1As shown in the figure, cuts having a width of 1 mm, a pitch of 6.4 mm, and a misalignment depth of 0 to 0.2 mm were formed in a manner that the cut front reaches the interface between the two layers on the side of the thermoplastic resin (A) layer and the side of the (B) layer using a cutting machine in a manner that the two surfaces are parallel and intersected alternately. Thereafter, test pieces were cut to a length of 80 mm and a width of 12.5 mm.

[0115] Using the test pieces on which the cut processing was performed, a compression test was performed, and the interlaminar shear strength was calculated from the load and the size of the test piece. The average value was set as the interlaminar shear strength of the fiber-reinforced resin base material in the integrally molded product.

[0116] (9) Thermal decomposition initiation temperature of thermoplastic resin

[0117] The thermal decomposition initiation temperature of the thermoplastic resin was measured based on JIS K7120 (1987) using a thermogravimetric measurement device (TG-DTA) under conditions of a temperature range of 50 to 600°C, a temperature increase rate of 10°C / minute, and a dry air atmosphere. At this time, 5 to 15 mg of the pellets, powder, or the like used in each resin layer or taken out by cutting each thermoplastic resin from the fiber-reinforced resin base material was placed in a platinum container to perform the measurement. From the obtained TG curve, the "initiation temperature Tl" at which the mass change began was taken as the thermal decomposition initiation temperature of each thermoplastic resin.

[0118] (10) Bonding strength of integrally molded product under high-temperature atmosphere

[0119] The space to be evaluated was surrounded with a constant-temperature tank so that the atmosphere temperature was 150°C, and otherwise, the bonding strength under a high-temperature atmosphere was evaluated in the same manner as the bonding strength of the integrally molded product of the above (6). After the test piece was disposed in the device, a tensile test was performed 5 minutes after the atmosphere temperature of the constant-temperature tank returned to 150°C, and the bonding strength was calculated from the obtained breaking load and the area of the bonding portion. The obtained bonding strength was evaluated as follows. E is unqualified.

[0120] Showed a bonding strength of 90% or more compared to the bonding strength of (6): A

[0121] Showed a bonding strength of 70% or more and less than 90% compared to the bonding strength of (6): B

[0122] Showed a bonding strength of 50% or more and less than 70% compared to the bonding strength of (6): C

[0123] Showed a bonding strength of 40% or more and less than 50% compared to the bonding strength of (6): D

[0124] Showed less than 40% compared to the bonding strength of (6): E.

[0125] <Materials used in Examples and Comparative Examples>

[0126] The following reinforcing fibers, thermoplastic resin (A), and thermoplastic resin (B) were used. The materials used in each of the examples and comparative examples are shown in Tables 1 to 3.

[0127] (1) Reinforcing fiber

[0128] An acrylonitrile copolymer copolymerized with itaconic acid was spun and fired, thereby obtaining carbon fibers having 24,000 total filaments, a specific gravity of 1.8, and different tow strength and tow elastic modulus.

[0129] • CF-1: Tow tensile strength: 5.9 GPa, tow elastic modulus: 290 GPa.

[0130] • CF-2: Tow tensile strength: 4.9 GPa, tow elastic modulus: 230 GPa.

[0131] (2) Thermoplastic resin (A) and thermoplastic resin (B)

[0132] • TP-2: A film having a unit area weight of 120 g / m 2 formed of PEEK (polyether ether ketone), PEEK 450G (manufactured by Victrex, crystalline, melting point 343°C, glass transition temperature 143°C, thermal decomposition initiation temperature 480°C)

[0133] • TP-3: A film having a unit area weight of 120 g / m 2 formed of PPS (polyphenylene sulfide), crystalline, melting point 284 [°C], glass transition temperature 90°C, thermal decomposition initiation temperature 460°C

[0134] • TP-5: A film having a unit area weight of 120 g / m 2 formed of a resin obtained by compounding a modified PP, unmodified polypropylene resin (Prime Polymer Co., Ltd. "Prime Polypro" (registered trademark) J105G) at 80 mass%, and acid-modified polypropylene resin (Mitsui Chemicals, Inc. "Admer" QB510) at 20 mass%, and melt-kneading using a twin-screw extruder (crystalline, melting point 165 [°C], thermal decomposition initiation temperature 310°C)

[0135] • TP-6: compounded in a manner that 95 mass% of PPS of TP-3, modified PPS, 5 mass% of aliphatic polycarbodiimide "CARBODILITE (registered trademark)" are blended, and melt-kneaded using a twin-screw extruder, a film having a weight per unit area of 120 g / m 2

[0136] • TP-7: a film having a weight per unit area of 120 g / m 3 2

[0137] • TP-8: a film having a weight per unit area of 120 g / m 3 2

[0138] • TP-9: a film having a weight per unit area of 120 g / m 3 2

[0139] • TP-10: a film having a weight per unit area of 120 g / m 2

[0140] (3) Compound (a)

[0141] • a-1: Sorbitol polyglycidyl ether (EX614B, manufactured by Nagase Chemtex Corporation)

[0142] • a-2: Diglycerol polyglycidyl ether (EX421, manufactured by Nagase Chemtex Corporation)

[0143] • a-3: Polyglycerol polyglycidyl ether (EX521, manufactured by Nagase Chemtex Corporation)

[0144] ​​​​​​​​•a-4: Polyethylene glycol diglycidyl ether (ethylene oxide content 13, manufactured by Nagase ChemteX Corporation)

[0145] •a-5: Bisphenol A ethylene oxide 15 molar adduct.

[0146] (4) Compound (b)

[0147] b-1: PO-modified polyethyleneimine (PP061, manufactured by Nippon Shokubai Co., Ltd.)

[0148] b-2: Polyallylamine (PAA-01, manufactured by Nippon Shokubai Co., Ltd.)

[0149] •b-3: Polyethyleneimine (SP-012, manufactured by Nippon Shokubai Co., Ltd.).

[0150] (5) Compound (c)

[0151] • C-1: Ethylene glycol diglycidyl ether (EX-810, manufactured by Nagase ChemteX Corporation)

[0152] • C-2: Bisphenol A type diglycidyl ether (jER828, manufactured by Mitsubishi Chemical Corporation).

[0153] <Example 1>

[0154] 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, the amount of compound a-4 attached was adjusted to 0.5 parts by mass for every 100 parts by mass of reinforcing fiber CF-1, thus producing a continuous reinforcing fiber.

[0155] Pull out the reinforcing fiber sheet formed by unidirectionally arranging the continuous reinforcing fibers (weight per unit area is 193 g / m²). 2The process involves moving the material unidirectionally and placing TP-8, a thermoplastic resin (B), on one surface of a continuous reinforcing fiber sheet. The thermoplastic resin (B) is then melted using an IR heater and adhered to the entire surface of one side of the continuous reinforcing fiber sheet. Pressure is applied using three pairs of clamping rollers maintained 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 object impregnated with the reinforcing fiber sheet, resulting in a semi-impregnated preform with the fiber reinforcing sheet exposed on the other side. TP-7, a thermoplastic resin (A), is then placed on the other side of the obtained semi-impregnated preform and melted using an IR heater, adhering to the surface of the semi-impregnated preform. Then, pressure is applied using 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) to impregnate the thermoplastic resin (A) with the fiber-reinforced resin intermediate, and then cooled to obtain the fiber-reinforced resin substrate.

[0156] Furthermore, the obtained fiber-reinforced resin substrate is used as a bonding component, such as Figure 5 As shown in (a), the material is arranged in mold 16. On the thermoplastic resin (A) layer side, carbon fiber reinforced thermoplastic resin (A) granules 17, which are produced by melt-blending thermoplastic resin (A) and carbon fiber (20% by mass) using an extruder, are injection molded. On the thermoplastic resin (B) layer side, carbon fiber reinforced thermoplastic resin (B) granules 19, which are produced by melt-blending thermoplastic resin (B) and carbon fiber (20% by mass) using an extruder, are injection molded to obtain an integral molded article.

[0157] The evaluation results of the obtained fiber-reinforced resin substrates and integrated molded products are shown in Table 1.

[0158] <Examples 2-10>

[0159] The compound imparted to the reinforcing fibers was modified as described in Table 1, except that the fiber-reinforced resin substrate was obtained by the same method as in Example 1. The evaluation results of the obtained fiber-reinforced resin substrate and the integrally molded article are shown in Table 1.

[0160] A comparison of Examples 1-10 shows the ideal property that the higher the surface free energy of the reinforcing fiber, the higher the interlaminar shear strength of the two resins, and the higher the bonding strength of the resulting integral molded article.

[0161] <Example 11>

[0162] As described in Table 2, reinforcing fibers CF-2 with different tensile strengths were used. Otherwise, fiber-reinforced resin substrates were obtained using the same method as in Example 1. The evaluation results of the obtained fiber-reinforced resin substrates and integrally molded articles are shown in Table 2.

[0163] A comparison of Examples 1 and 11 shows that if the tensile strength of the reinforcing fiber bundle is high, the interlayer shear strength of the two resins is increased, and the bonding strength of the resulting integrated molded product is also improved.

[0164] <Examples 12-17>

[0165] The thermoplastic resins used in thermoplastic resins (A) and (B) were changed as described in Table 2, except that the fiber-reinforced resin substrate was obtained in the same manner as in Example 1. The heating temperature in the clamping rollers was set to a temperature 100°C lower than the melting point of the thermoplastic resins used in each example. The evaluation results of the obtained fiber-reinforced resin substrates and integral molded articles are shown in Table 2.

[0166] By changing the combination of thermoplastic resins in Examples 1 and 12-17, one-piece molded articles with high bonding strength were also obtained.

[0167] <Example 18>

[0168] Use 250g / m² of unit area weight 2 The fiber-reinforced resin substrate was obtained by operating in the same manner as in Example 1, except for the reinforcing fiber sheet. The evaluation results of the obtained fiber-reinforced resin substrate and the integrally molded article are shown in Table 2.

[0169] A comparison of Examples 1 and 18 revealed the desirable properties that increasing the volume content of the reinforcing fibers resulted in higher interlaminar shear strength of the two resins and improved bonding strength of the resulting integral molded article.

[0170] <Example 19>

[0171] In the process of drawing out a reinforcing fiber sheet formed by unidirectionally arranging continuous reinforcing fibers and impregnating thermoplastic resin (A) and thermoplastic resin (B) into the unidirectionally traveling reinforcing fiber sheet, the traveling speed of the reinforcing fiber sheet is set to twice the normal speed. Otherwise, the fiber-reinforced resin substrate is obtained by operating in the same manner as in Example 1. By setting the traveling speed of the reinforcing fiber sheet to twice the normal speed, the impregnation time of each thermoplastic resin in the reinforcing fiber sheet is shortened. Therefore, the resulting fiber-reinforced resin substrate is in a state where each thermoplastic resin is not completely impregnated to the center of the reinforcing fiber sheet, and a boundary region with gaps is formed between the opposite surfaces of each resin layer.

[0172] Next, the thermoplastic resin TP-7 and the carbon fiber TP-1, the thermoplastic resin TP-8 and the carbon fiber TP-1 were melt-kneaded with 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 The carbon fiber-reinforced thermoplastic resin pellets were injection-molded to produce a flat plate 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 were overlaid in this order, and heated and pressurized with a press molding machine having a hot platen temperature of 360°C, and directly cooled in the pressurized state to produce an integrated molded product. At this time, the thermoplastic resin (A) layer of the fiber-reinforced resin substrate was arranged so as to be in contact with the flat plate obtained from the carbon fiber-reinforced thermoplastic resin (A) pellets.

[0173] The integrated molded product was subjected to notch processing, and a compression test was performed using a test piece. The results obtained are shown in Table 3.

[0174] <Comparative Example 1>

[0175] A reinforcing fiber sheet having a unit area weight (97 g / m 2 ) of continuous reinforcing fibers arranged in a unidirectional manner was drawn out so as to travel in a unidirectional manner, and TP-7 as the thermoplastic resin (A) was arranged on one surface of the continuous reinforcing fiber sheet, and heated with an IR heater to melt the thermoplastic resin (A) and adhere it to the entire surface of one side of the continuous reinforcing fiber sheet, and pressurized with a nip roller maintained at a temperature 100°C lower than the melting point of the thermoplastic resin (A) to obtain a fiber-reinforced resin substrate having only the thermoplastic resin (A) in which the thermoplastic resin was completely impregnated in the reinforcing fiber sheet. Further, TP-7 as the thermoplastic resin (A) was changed to TP-8 as the thermoplastic resin (B), and otherwise, a fiber-reinforced resin substrate having only the thermoplastic resin (B) was obtained by the same method. The two kinds of fiber-reinforced resin substrates were overlaid, heated with an IR heater to melt the thermoplastic resin (B), and pressurized with a nip roller maintained at a temperature 100°C lower than the melting point of the thermoplastic resin (B) to integrate the two kinds of fiber-reinforced resin substrates with each other to obtain a fiber-reinforced resin substrate. The evaluation results of the fiber-reinforced resin substrate obtained are shown in Table 3.

[0176] <Comparative Example 2>

[0177] A laminate of a thermoplastic resin film made by laminating TP-7 as the thermoplastic resin (A) and TP-8 as the thermoplastic resin (B) was heated using an IR heater without using continuous reinforcing fibers, the thermoplastic resin (A) was melted, and was attached to the surface of the thermoplastic resin (B). Then, using 3 pairs of nip rollers maintained at a temperature (200°C) that was 100°C lower than the melting point of the thermoplastic resin (A), pressure was applied to obtain a two-layered thermoplastic resin film.

[0178] The evaluation results of the obtained thermoplastic resin film are shown in Table 3.

[0179] Comparing Example 1 and Comparative Example 2 with Example 1, although the same kind of thermoplastic resins were used, since there were no reinforcing fibers that spanned the boundary region formed by the two thermoplastic resins, high interlayer shear strength could not be exhibited. In addition, although they can be used to obtain an integrated molded product, they did not have sufficient joint strength.

[0180] <Comparative Example 3>

[0181] The thermoplastic resins used in the thermoplastic resin (A) and / or the thermoplastic resin (B) were changed as described in Table 3, and otherwise, the same operations as in Example 1 were performed to obtain a fiber-reinforced resin substrate. The heating temperature in the nip rollers was set to a temperature that was 100°C lower than the melting point of the thermoplastic resin used. The properties of the obtained fiber-reinforced resin substrate are shown in Table 3.

[0182] Comparing Example 1 and Comparative Example 3, since thermoplastic resins having a melting point of 200°C or less were used, the joint strength under a high-temperature atmosphere could not be maintained, and they were not suitable for use in a high-temperature environment.

[0183] <Reference Example 1>

[0184] Instead of using a fiber-reinforced resin substrate as a joint member, the same operations as in Example 1 were performed, and only the carbon fiber-reinforced thermoplastic resin (A) pellets were injection-molded to produce a molded member (A) that was not integrated with the fiber-reinforced resin substrate. Next, as shown in (b) of FIG. 16, after the molded member (A) was disposed in the mold 16, carbon fiber-reinforced thermoplastic resin (B) pellets were injection-molded to produce a joint strength test piece for an integrated molded product. Figure 5

[0185] In Reference Example 1, although an integrated molded product could be obtained, it did not have sufficient joint strength, and the evaluation of the joint strength of the integrated molded product was D, and the evaluation of the joint strength under a high-temperature atmosphere was C.

[0186] [Table 1]

[0187] ​

[0188] [Table 2]

[0189]

[0190] [Table 3]

[0191] Table 3

[0192]

[0193] BRIEF DESCRIPTION OF DRAWINGS

[0194] 1: Fiber-reinforced resin base material

[0195] 2: Reinforcing fiber

[0196] 3: Thermoplastic resin (A) layer

[0197] 4: Thermoplastic resin (B) layer

[0198] 5: Interface

[0199] 6: Cutout

[0200] 7: Fiber direction of reinforcing fiber

[0201] 8: Observation cross section

[0202] 9: Reference line

[0203] 10: Vertical line

[0204] 11: Cross-sectional curve

[0205] 12: Opposite surface of thermoplastic resin (A) layer

[0206] 13: Opposite surface of thermoplastic resin (B) layer

[0207] 14: Boundary region

[0208] 15: Air (void)

[0209] 16: Mold

[0210] 17: Carbon fiber-reinforced thermoplastic resin (A) pellets

[0211] 18: Injection molding machine

[0212] 19: Carbon fiber-reinforced thermoplastic resin (B) pellets

[0213] 20: Carbon fiber-reinforced thermoplastic resin (A) molded article

[0214] 21: Carbon fiber-reinforced thermoplastic resin (B) molded article

[0215] 22: Test piece for measuring the joint strength of an integrally molded product

[0216] 23: Notched test piece

Claims

1. A fiber-reinforced resin base material which is a fiber-reinforced resin base material in which a thermoplastic resin (A) and a thermoplastic resin (B) are impregnated in continuous reinforcing fibers, wherein a layer of the thermoplastic resin (A) which is exposed on one surface and a layer of the thermoplastic resin (B) which is exposed on the other surface form a boundary region, the layer of the thermoplastic resin (A) which is exposed on one surface and the layer of the thermoplastic resin (B) which is exposed on the other surface are joined with an interface formed therebetween, at least a part of the continuous reinforcing fibers is present across the boundary region, the thermoplastic resin (A) and the thermoplastic resin (B) are each a crystalline resin having a melting point of 200°C or higher, and the continuous reinforcing fibers are reinforcing fibers present in the form of a fiber bundle in which reinforcing fibers of long fibers are aligned in one direction, a laminate of fiber bundles, or a woven fabric. The difference between the melting points of the thermoplastic resin (A) and the thermoplastic resin (B) is 10 to 50°C. The interlaminar shear strength of the layer of the thermoplastic resin (A) and the layer of the thermoplastic resin (B) is 30 MPa or higher as measured according to JIS K7092-2005. The thermoplastic resin (A) and the thermoplastic resin (B) are different resin types. The thermoplastic resin (A) is a resin selected from the group consisting of polyarylene ether ketone, polyphenylene sulfide, polyether ether ketone, and polyether ketone ketone.

2. The fiber reinforced resin matrix of claim 1, wherein, The thickness of the layer of the thermoplastic resin (A) is 20 to 80% of the thickness of the fiber-reinforced resin base material.

3. The fiber reinforced resin matrix material of claim 1 or 2, wherein, The volume content of the reinforcing fibers in the layer of the thermoplastic resin (A) and the layer of the thermoplastic resin (B) is 30% or higher.

4. The fiber reinforced resin matrix of claim 1 or 2, wherein, The melting points of the thermoplastic resin (A) and the thermoplastic resin (B) are each 250°C or higher, and / or the glass transition temperatures of the thermoplastic resin (A) and the thermoplastic resin (B) are each 100°C or higher.

5. The fiber reinforced resin matrix material of claim 1 or 2, wherein, The thermoplastic resin (A) and the thermoplastic resin (B) have a thermal decomposition onset temperature of 480°C or higher.

6. The fiber reinforced resin matrix of claim 1 or 2, wherein, The tensile strength of the reinforcing fibers is 5.5 GPa or higher.

7. The fiber reinforced resin matrix of claim 1 or 2, wherein, In a cross section in the thickness direction obtained by cutting at an angle of 45 degrees with respect to the fiber direction of the reinforcing fibers, the cross-sectional curve formed by the interface has a roughness average length RSm defined by JIS B0601-2001 of 100 μm or less and a roughness average height Rc of 3.5 μm or more.

8. The fiber reinforced resin matrix of claim 1 or 2, wherein, The thickness of the fiber-reinforced resin base material is 500 μm or less.

9. The fiber reinforced resin matrix of claim 1 or 2, wherein, 14. A prepreg which is a fiber-reinforced resin base material as described in any one of claims 1 to 13 arranged between a member A having a thermoplastic resin (A) on the surface and a member B having a thermoplastic resin (B) on the surface such that the layer of the thermoplastic resin (A) of the fiber-reinforced resin base material is in contact with the thermoplastic resin (A) of the member A and the layer of the thermoplastic resin (B) is in contact with the thermoplastic resin (B) of the member B.

10. The fiber-reinforced resin matrix according to claim 1 or 2, which is made using a reinforcing fiber having a surface free energy of 10 to 50 mJ / m2 as measured by the Wilhelmy method as the reinforcing fiber. 2 10. The fiber-reinforced resin matrix according to claim 1 or 2, which is made using a reinforcing fiber having a surface free energy of 10 to 50 mJ / m2 as measured by the Wilhelmy method as the reinforcing fiber.

11. The fiber reinforced resin matrix of claim 1 or 2, wherein, ​ 12. The fiber reinforced resin matrix of claim 1 or 2, wherein, ​ 13. The fiber reinforced resin matrix of claim 1 or 2, wherein, ​ ​ 15. An integrally molded product which is formed by fusion of a thermoplastic resin (A) layer of the fiber-reinforced resin substrate of any one of claims 1 to 13 to the thermoplastic resin (A) of a member A having the thermoplastic resin (A) on a surface and fusion of a thermoplastic resin (B) layer to the thermoplastic resin (B) of a member B having the thermoplastic resin (B) on a surface via the fiber-reinforced resin substrate.

16. The integrally formed article of claim 15, wherein, The member A and / or the member B is a fiber-reinforced resin.

17. A method for producing a fiber-reinforced resin substrate, which is a method for producing a fiber-reinforced resin substrate in which a thermoplastic resin (A) and a thermoplastic resin (B) are impregnated in a continuous reinforcing fiber, characterized by, impregnating the thermoplastic resin (B) from the other surface of the semi-impregnated preform after impregnating the thermoplastic resin (A) from one surface of a continuous reinforcing fiber sheet to obtain a semi-impregnated preform in which a thermoplastic resin (A) layer is exposed on one surface and a continuous reinforcing fiber sheet is exposed on the other surface; or impregnating the thermoplastic resin (A) from the other surface of the semi-impregnated preform after impregnating the thermoplastic resin (B) from one surface of a continuous reinforcing fiber sheet to obtain a semi-impregnated preform in which a thermoplastic resin (B) layer is exposed on one surface and a continuous reinforcing fiber sheet is exposed on the other surface, the reinforcing fiber is a reinforcing fiber existing in the form of a fiber bundle in which reinforcing fibers of long fibers are arranged in one direction, a laminate of fiber bundles, or a woven fabric, the thermoplastic resin (A) layer exposed on one surface and the thermoplastic resin (B) layer exposed on the other surface form an interface and are joined.

Images