Composite materials

Abstract

To provide a composite member in which a reinforcement member is joined to a reinforcement-target member through an adhesive layer, and in which an outermost surface layer in contact with the adhesive layer of the reinforcement-target member or the reinforcement member is composed of a unidirectional prepreg including reinforcement fiber and thermosetting resin, and in which instability of resistance against peeling of a joint portion is radically remedied, and which therefore is easily designed and has high reliability.SOLUTION: A composite member is provided in which a reinforcement member having an aspect ratio represented by expression: aspect ratio=projection length of reinforcement member (m) / projection width of reinforcement member (m) of 1 or more and 1,000,000,000 or less is joined to a reinforcement-target member through an adhesive layer, wherein a part or all of an outermost surface layer of the reinforcement member, in contact with the adhesive layer is composed of a unidirectional prepreg including reinforcement fiber and thermosetting resin, and an angle α in top view between an orientation direction of the reinforcement fiber of the unidirectional prepreg and a longitudinal direction of the projection length of the reinforcement member is 30°≤α<90°.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a composite member in which a reinforcing member is joined to a reinforced member via an adhesive layer, and in which part or all of the outermost layer of the reinforcing member or reinforced member involved in the joining is made of unidirectional prepreg. [Background technology]

[0002] Components made from prepregs, which are made by impregnating reinforcing fibers with thermosetting resins, are particularly suitable for use in aircraft due to their lightweight and high strength characteristics. When using this type of material to manufacture aircraft fuselage barrels, wings, tails, etc., composite components are preferably used, in which reinforcing members such as stringers are bonded to a panel-like surface member (reinforced member), which has low rigidity against bending loads on its own. The composite construction of components provides the desired rigidity for the airframe structure. In this type of application, stabilizing the strength of the bonds between components and controlling reliability is a technical field that has received particular attention not only during aircraft operation but also in aircraft design and manufacturing.

[0003] Patent Document 1 discloses a composite member in which a stringer-like reinforcing member is fastened to a panel-like member with fasteners for integration. This mechanical fastening method is applicable regardless of the type of material used to construct the member, and also provides high fastening reliability. In manufacturing, holes are drilled in each of the separate members to be fastened, and the members are positioned relative to each other before fastening the fasteners. This typically involves fastening the members together with multiple fasteners spaced apart. Since the above process is repeated the desired number of times, the entire process takes a long time and it is difficult to improve efficiency. Furthermore, the weight of the metal fasteners themselves compromises the lightweight nature of the composite member.

[0004] Separately, Patent Document 2 discloses a panel-shaped component manufactured from a prepreg of reinforcing fiber and thermosetting resin, and then adhesively bonded to the panel using stringers as reinforcing members. The adhesive is a lightweight resin material, and does not increase the weight of the composite component, as occurs with fasteners. Furthermore, the adhesive bonding process does not require drilling holes in the component, making it easier than fasteners.

[0005] Patent Document 3 discloses a configuration for increasing the strength of the joint in an adhesive bonding between members made of a composite material containing reinforcing fibers. It states that the strength of the joint is increased by forming an uneven bonding surface in the cross section of the joint between the composite members, where the adhesive contacts the area of ​​each member that is in contact with the adhesive. A similar configuration is also disclosed in Patent Document 4. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] :International Publication No. 2010 / 046684 [Patent Document 2] :International Publication No. 2018 / 170330 [Patent Document 3] :International Publication No. 2006 / 089534 [Patent Document 4] :International Publication No. 2004 / 060658 Summary of the Invention [Problem to be solved by the invention]

[0007] As described in Patent Documents 2 to 4, these adhesive bonding methods offer a solution to the problems associated with conventional fastener fastening for composite materials containing reinforcing fibers. However, when prepregs containing reinforcing fibers and thermosetting resins are used as reinforcing or reinforced components, a unique characteristic of this type of material is that they exhibit different stiffness and strength depending on the fiber orientation, which can lead to a problem of unstable peel loads at the bonded surfaces between components. This variation in bond strength makes it difficult to design the bond between components, and remains a problem that must be solved in the bonding of components made of composite materials.

[0008] An object of the present invention is to provide a composite member that is easy to design and highly reliable, by drastically improving the instability of resistance to peeling at the joint as described above, when a reinforcing member is bonded to a reinforced member via an adhesive layer, and the outermost layer in contact with the adhesive layer of the reinforced member or the reinforcing member is composed of a unidirectional prepreg containing reinforcing fibers and a thermosetting resin. [Means for solving the problem]

[0009] The present invention provides a composite member in which a reinforcing member having an aspect ratio according to the following formula (1) greater than 1 and smaller than 1,000,000,000 is bonded to a reinforced member via an adhesive layer, The adhesive layer contains reinforcing fibers that constitute at least one of the reinforcing member and the reinforced member, and A composite member in which part or all of the outermost layer of the reinforcing member in contact with the adhesive layer is made of a unidirectional prepreg containing reinforcing fibers and a thermosetting resin, and the angle α between the orientation direction of the reinforcing fibers of the unidirectional prepreg and the longitudinal direction of the projected length of the reinforcing member in a top view is 30°≦α<90°. Aspect ratio = Projected length of reinforcing member (m) / Projected width of reinforcing member (m) (1)

[0010] Another aspect of the present invention is a composite member in which a reinforcing member having an aspect ratio according to the following formula (1) greater than 1 and smaller than 1,000,000,000 is bonded to a reinforced member via an adhesive layer, The adhesive layer contains reinforcing fibers that constitute at least one of the reinforcing member and the reinforced member, andA composite member in which part or all of the outermost layer of the reinforced member in contact with the adhesive layer is made of a unidirectional prepreg containing reinforcing fibers and a thermosetting resin, and the angle β formed between the orientation direction of the reinforcing fibers of the unidirectional prepreg and the longitudinal direction of the projected length of the reinforcing member when viewed from above is 30°≦β<90°. Aspect ratio = Projected length of reinforcing member (m) / Projected width of reinforcing member (m) (1)

[0011] According to a preferred embodiment of the composite member of the present invention, in the reinforced member to which the reinforcing member is joined, the angle α of which is 30°≦α<90°, the angle β satisfies 30°≦β<90°.

[0012] In a preferred embodiment of the composite member of the present invention, the adhesive layer is made of a thermosetting resin.

[0013] According to a preferred embodiment of the composite material of the present invention, the thermosetting resin is at least one selected from the group consisting of epoxy resin, benzoxazine resin, cyanate ester resin, bismaleimide resin, and phenol resin.

[0014] In a preferred embodiment of the composite member of the present invention, the adhesive layer is made of a thermoplastic resin.

[0015] According to a preferred embodiment of the composite member of the present invention, the thermoplastic resin is at least one selected from the group consisting of polyamide resin, polyphenylene sulfide resin, polyether ketone ketone resin, and polyether ether ketone resin.

[0016] In a preferred embodiment of the composite member of the present invention, the adhesive layer contains reinforcing fibers that constitute at least one of the reinforcing member and the reinforced member.

[0017] According to a preferred embodiment of the composite member of the present invention, the adhesive layer has a thickness of 10 μm or more and less than 500 μm. [Effects of the Invention]

[0018] In a composite member in which a reinforcing member is joined to a reinforced member via an adhesive layer, the orientation direction of the reinforcing fibers of the unidirectional prepreg constituting the outermost layer of the reinforcing member or the reinforced member is within a specific range relative to the direction of the main load received by the reinforcing member, thereby inducing fracture in the reinforcing member or the reinforced member, and providing a composite member with reduced variation in bonding strength. [Brief explanation of the drawings]

[0019] [Figure 1] Fig. 1(a) is a perspective view showing an example of a composite member of the present invention. Fig. 1(b) is a perspective view showing the outermost layer in contact with the adhesive layer of the reinforcing member and the reinforced member, seen through the reinforcing member of Fig. 1(a). In this example, a unidirectional prepreg is disposed on the outermost surface of the reinforcing member. Fig. 1(c) is a top view of Fig. 1(b). [Figure 2] Fig. 2(a) is a perspective view showing an example of a composite member of the present invention. Fig. 2(b) is a perspective view showing the outermost layer in contact with the adhesive layer of the reinforcing member and the reinforced member, seen through the reinforcing member of Fig. 2(a). In this example, a unidirectional prepreg is disposed on the outermost surface of the reinforced member. Fig. 2(c) is a top view of Fig. 2(b). [Figure 3] Figure 3(a) is a perspective view of a composite member similar to Figure 2(a), showing the outermost layer in contact with the adhesive layer of the reinforcing member and the reinforced member. In this example, unidirectional prepregs are placed on the outermost surfaces of both the reinforcing member and the reinforced member. Figure 3(b) is a top view of Figure 3(a). [Figure 4] Figure 4(a) shows an example of a reinforcing member when the reinforcing member has an in-plane bent shape, and Figure 4(b) shows an example of a reinforcing member when the reinforcing member has an out-of-plane bent shape. [Figure 5] Figure 5(a) is a top view of the outermost layer in contact with the adhesive layer of the reinforcing member in Figure 4(a). Figure 5(b) is a perspective view of the outermost layer in contact with the adhesive layer of the reinforcing member in Figure 4(b), and is a diagram illustrating the coordinate system x'y' defined for the part with out-of-plane bending. Figure 5(c) is a top view of Figure 5(b). DETAILED DESCRIPTION OF THE INVENTION

[0020] Next, the details of the embodiment of the molded article of the present invention will be described.

[0021] The composite member of the present invention comprises a long reinforcing member, a reinforced member, and an adhesive layer, the reinforcing member and the reinforced member being joined via the adhesive layer, and part or all of the outermost layer in contact with the adhesive layer of the reinforcing member or the reinforced member being made of a unidirectional prepreg containing reinforcing fibers and a thermosetting resin, and the orientation direction of the reinforcing fibers of the unidirectional prepreg is within a specific range.

[0022] A part or all of the outermost layer in contact with the adhesive layer is made of unidirectional prepreg, and the orientation direction of the reinforcing fibers of the unidirectional prepreg may be within a specific range in only the reinforcing member, only the reinforced member, or both the reinforcing member and the reinforced member.

[0023] In other words, if the angle formed between the orientation direction of the reinforcing fibers of part or all of the unidirectional prepreg of the outermost layer in contact with the adhesive layer of the reinforcing member and the longitudinal direction of the projected length of the reinforcing member in a top view is α, the composite member of the present invention has an angle of 30°≦α<90°.

[0024] Furthermore, if the angle formed between the orientation direction of the reinforcing fibers of part or all of the unidirectional prepregs in the outermost layer that contacts the adhesive layer of the reinforced member and the longitudinal direction of the projected length of the reinforcing member in a top view is β, the composite member of the present invention has a β of 30°≦β<90°.

[0025] Additionally, a preferred embodiment of the composite member of the present invention is one in which 30°≦α<90° and 30°≦β<90°.

[0026] The angle α formed in a top view is shown in Figure 1. Figure 1(a) shows a perspective view of an example of a composite member of the present invention, and Figure 1(b) shows a perspective view of the reinforcing member of Figure 1(a) showing the outermost layer in contact with the adhesive layer of the reinforcing member and the reinforced member. In this example, a unidirectional prepreg is disposed on the outermost surface of the reinforcing member. Figure 1(c) shows a top view of Figure 1(b), and the angle α is shown as 5 and 15 in Figure 1(c). Figure 2 also shows an example of the angle β formed in a top view. Figure 2(a) shows a perspective view of an example of a composite member of the present invention, and Figure 2(b) shows a perspective view of the reinforcing member of Figure 2(a) showing the outermost layer in contact with the adhesive layer of the reinforcing member and the reinforced member. In this example, a unidirectional prepreg is disposed on the outermost surface of the reinforced member. Figure 2(c) is a top view of Figure 2(b), and the angle β is shown at 6 and 16 in Figure 2(c). Figure 3 also shows an example of a structure in which both the angle α and the angle β can be defined simultaneously. Figure 3(a) shows a perspective view of a composite member similar to Figure 2(a), looking through the reinforcing member and showing the outermost layer in contact with the adhesive layer of the reinforcing member and the reinforced member. In this example, unidirectional prepreg is placed on the outermost surface of both the reinforcing member and the reinforced member. Figure 3(b) is a top view of Figure 3(a), and α and β are shown at 5 and 15 and 6 and 16 in Figure 3(b), respectively.

[0027] In the reinforcing member or the reinforced member, the angle α or the angle β is preferably defined as above for the entire outermost layer in contact with the adhesive layer. Furthermore, in the case of a long reinforcing member, from the viewpoint that a large load is applied to the longitudinal ends, it is particularly preferable that the angle α or the angle β be defined within a range of 10% of the projected length of the reinforcing member at each of the longitudinal ends of the reinforcing member.

[0028] Fiber-reinforced materials, such as carbon fiber prepregs, are brittle in fracture and often exhibit the characteristic of rapidly progressing fracture and losing load when a certain load is exceeded. Furthermore, the load also varies. When forming a joint structure using this type of material, if the angle α or angle β is within the above-mentioned angle range, fracture of the base material, i.e., the reinforcing member or the reinforced member, is easily induced at the joint interface. Furthermore, when α or β is within the above-mentioned angle range, the strength of the base material varies little. This means that fracture of the joint structure can be induced near the desired strength, resulting in a composite member with stable joint strength.

[0029] The range of the formed angle α or the formed angle β is more preferably 45°<α<85° or 45°<β<85°, and even more preferably 60°<α<85° or 60°<β<85°. When the formed angle α or the formed angle β is greater than 45° or 60°, the variation in strength of the reinforcing member or the reinforced member is further reduced, and the strength of the composite member can be stabilized. Furthermore, when the formed angle α or the formed angle β is less than 85°, the formability into complex shapes is improved. As a result, the shape of the joining surface can be stabilized, and the strength of the composite member can be stabilized.

[0030] [Reinforcing material] The reinforcing member of the present invention is characterized in that its aspect ratio is greater than 1 and less than 1,000,000,000. Here, the aspect ratio of the reinforcing member is defined as the projected length (m) of the reinforcing member divided by the projected width (m) of the reinforcing member. Here, the projected length is defined as the longest dimension along the shape of the projected shape of the reinforcing member when viewed from above, and the projected width is defined as the average dimension of the projected shape when viewed from above in a direction approximately perpendicular to the projected length direction.

[0031] The aspect ratio of the reinforcing member is preferably greater than 10 and less than 10,000,000, and more preferably greater than 100 and less than 10,000. Increasing the aspect ratio increases the efficiency of the reinforcing effect in the load direction. Furthermore, increasing the projected width of the reinforcing member while keeping the projected length the same decreases the aspect ratio. However, increasing the projected width of the reinforcing member increases the second moment of area of ​​the reinforcing member, improving buckling resistance and enhancing the reinforcing effect.

[0032] The reinforcing member restrains deformation in the longitudinal direction of the projected length of the reinforcing member in a composite structure integrated with the reinforced member to which the reinforcing member is joined, by its own rigidity.

[0033] The effect of this reinforcing member is most effectively manifested when a bending or torsional load is applied to the composite structure. To enhance the effect, it is preferable to select a cross-sectional shape of the reinforcing member with a high moment of inertia. To increase the moment of inertia while also increasing the lightness of the reinforcing member, the reinforcing member can have a hollow cross-section. Here, "hollow" refers to the formation of a closed space between the reinforcing member and the reinforced member at the cross section of the joint between the reinforcing member and the reinforced member. This can be achieved in the form of a reinforcing member known as a hat stringer or omega stringer.

[0034] The reinforcing member may have a shape that is twisted or bent in the longitudinal direction so as to conform to the shape of the reinforced member. The reinforcing member has a portion for joining to the reinforced member, and this portion may be flat or curved. The shape of the joining surface of this reinforcing member matches the shape of the joining surface on the reinforced member side, and when the reinforcing member and the reinforced member are joined together, it is preferable that they be in contact across the joining surface or have a roughly uniform clearance, in order to increase the stability of the joining strength.

[0035] The projected length and projected width of a reinforcing member when the reinforcing member has a twisted or bent shape are shown schematically in Figure 4. Figure 4(a) shows an example of a reinforcing member when the reinforcing member has an in-plane bent shape, and Figure 4(b) shows an example of a reinforcing member when the reinforcing member has an out-of-plane bent shape.

[0036] When a reinforcing member has a twisted or bent shape, the longitudinal direction of the projected length of the reinforcing member is defined as the longitudinal direction of the projected length in a top view along the shape at each position of the longitudinal shape. Figure 5 shows a schematic example of the longitudinal direction of the projected length defined along the shape and the top view direction. Figure 5(a) shows a perspective view of the reinforcing member in Figure 4(a), showing the top view of the outermost layer in contact with the adhesive layer. In this example, the orientation angle of the reinforcing fibers in the outermost layer is constant in space, but the longitudinal direction of the projected length of the reinforcing member changes depending on the longitudinal position of the reinforcing member. Therefore, the magnitude of the angle α varies depending on the longitudinal position of the reinforcing member's projected length. An example of an angle α that varies depending on the longitudinal position of the reinforcing member's projected length is shown in 37. Figure 5(b) shows a perspective view of the reinforcing member in Figure 4(b), showing the outermost layer in contact with the adhesive layer. In this example, because the reinforcing member has an out-of-plane bent shape, the top view direction varies depending on the longitudinal position of the reinforcing member's projected length. At both ends of the reinforcing member, the plane approximately perpendicular to the top view direction is the xy plane, while at the central inclined portion of the reinforcing member, the plane approximately perpendicular to the top view direction is the x'y' plane. Figure 5(c) illustrates the angle α defined by the xy plane and the x'y' plane, with Figure 5(b) showing the top view. At both ends of the reinforcing member, the top view direction is approximately perpendicular to the xy plane, so the angle α is defined in the xy plane. At the central inclined portion of the reinforcing member, the top view direction is approximately perpendicular to the x'y' plane, so the angle α is defined in the x'y' plane. The angle α in this case is shown as 47. While the above example focuses on the angle α, the angle β is also defined in the same way as the angle α.

[0037] The prepreg, which is a constituent element of the reinforcing member according to the present invention, is a sheet-like molding material in which reinforcing fibers are impregnated with a thermosetting resin.

[0038] The type of reinforcing fiber is not particularly limited, and carbon fiber, glass fiber, aramid fiber, etc. can be used, and a hybrid structure combining these is also possible. A form containing carbon fiber is preferred in order to increase the strength of the molded product.

[0039] The thermosetting resin contained in the prepreg of the present invention can be any of various thermosetting resins. It is preferably at least one selected from epoxy resin, benzoxazine resin, cyanate ester resin, bismaleimide resin, phenol resin, and modified resins thereof. Epoxy resin is particularly preferred due to its excellent mechanical properties. For applications requiring heat resistance, it is recommended to select cyanate ester resin or bismaleimide resin.

[0040] The reinforcing member of the present invention is preferably composed, in part or in whole, of a thermosetting unidirectional prepreg. Unidirectional prepregs, which are made by impregnating a fiber sheet in which continuous fibers are aligned in one direction with a resin, are an embodiment in which the strength characteristics of the reinforcing fibers are efficiently exhibited. Since they exhibit high elastic modulus and strength in the orientation direction of the reinforcing fibers, a laminate of unidirectional prepregs may be used to impart the desired thickness, rigidity, and strength to the reinforcing member. A laminated composite plate obtained by stacking unidirectional prepregs while changing the fiber angle and then baking the resulting laminate can be suitably used for the reinforced member.

[0041] A form of the reinforced member that is excellent in productivity is a molded article made of a metal material. In this case, aluminum alloys are preferred, and aluminum-lithium alloys are particularly preferred, because of the balance between light weight and strength.

[0042] The autoclave molding method, press molding method, and ultraviolet irradiation method are preferably used to manufacture the reinforcing member of the present invention. Among these, autoclave molding allows for precise application of heat and pressure to the prepreg laminate, thereby improving the quality of the reinforcing member and making it suitable for aircraft applications. Furthermore, when the laminate contains a fiber substrate, the so-called resin transfer molding (RTM) method is preferably used. By injecting a matrix resin from the outside of the laminate using vacuum or pressure into the voids in the fiber substrate, filling the voids with resin, and then maintaining the laminate at a desired temperature, curing of the matrix resin and the resin contained in the prepreg is induced, resulting in a baked and hardened laminated composite board. The type of matrix resin is not limited, but the same type of resin as the prepreg can be used. Furthermore, the composition of the matrix resin can be appropriately adjusted to optimize the desired heat resistance, mechanical properties, and impregnation ability into the fiber substrate.

[0043] [Reinforced member] The reinforced member of the present invention is a panel-shaped member. Examples include the so-called outer shell of an aircraft wing or fuselage. In particular, for aircraft and other flying bodies, the reinforced member is required to be lightweight. Increasing the thickness of a panel-shaped member in order to increase its structural rigidity will result in a loss of lightweight properties. Therefore, it is preferable to use the panel-shaped member as a composite member integrated with the above-mentioned reinforcing member.

[0044] The material constituting the reinforced member can be the same as the material used for the reinforcing member.

[0045] Unidirectional prepregs, which are made by impregnating aligned reinforcing fibers with thermosetting resin, are highly compatible with automated tape layup (ATL) systems, and are therefore preferred because they can dramatically increase productivity, especially when the reinforced member is in the form of a large panel.

[0046] An example of a reinforced member that is highly productive is a sheet metal molded product made of a metal material. In this case, aluminum alloys are preferred, with aluminum-lithium alloys being particularly preferred, due to their balance of light weight and strength.

[0047] Since the reinforced member of the present invention is bonded to the reinforcing member via an adhesive layer, when the reinforcing member bears a major load, the outermost layer of the reinforced member to which the load is transmitted is subjected to a load of the same magnitude but in the opposite direction to the load in accordance with the third law of motion. Therefore, it is preferable that the outermost layer of the reinforced member that contacts the adhesive layer has the same variation in bonding strength as the outermost layer of the reinforcing member that contacts the adhesive layer.

[0048] [Adhesive layer] The adhesive layer according to the present invention, interposed between the reinforcing member and the reinforced member, functions to distribute the external force applied to the composite member between the reinforcing member and the reinforced member, thereby enabling the composite member to acquire the designed rigidity and strength.

[0049] In order to ensure a strong bond and not impair the lightweight nature of the composite member, the components of the adhesive layer are preferably selected from resin materials.

[0050] The thermosetting resin used in the adhesive layer is preferably at least one selected from the group consisting of epoxy resins, benzoxazine resins, cyanate ester resins, bismaleimide resins, and phenolic resins.

[0051] In bonding, an uncured resin material is placed as an adhesive layer between a reinforcing member and a reinforced member, which are in a hardened state, and the adhesive layer is solidified by applying heat and pressure to obtain a bonded composite member. Even if the reinforcing member or the reinforced member is in an uncured state, a resin material that will become an adhesive layer can be applied or placed between them, and the thermosetting resin contained in the reinforcing member or the reinforced member can be solidified while the adhesive layer is hardened to obtain a composite member.

[0052] Solidification of the adhesive layer can be carried out in an autoclave or similar molding device having a heating and / or pressure mechanism.

[0053] Furthermore, it is possible to manufacture a reinforcing member and a reinforced member with an adhesive component made of a thermoplastic resin fixed to their surfaces, and then join them by using the thermoplastic resin on the surface of each member as an adhesive layer.

[0054] An example of a method for producing the reinforcing member and the reinforced member is to laminate a sheet-like material made of a thermoplastic resin, which serves as an adhesive component, onto the outermost layer of a prepreg containing a thermosetting resin, and while maintaining the temperature above the melting point of the thermoplastic resin, apply pressure to form the prepreg into the desired shape and integrate the prepreg and the thermoplastic resin.

[0055] The composite member is preferably formed by joining the reinforcing member and the reinforced member by thermal welding. For example, the joining portion may be heated by infrared rays, a laser, or the like, and then the reinforcing member and the reinforced member are pressed together to weld them. Alternatively, ultrasonic welding or induction welding may also be used.

[0056] The form of the sheet-like material made of thermoplastic resin is not particularly limited, but from the viewpoint of ease of handling, it is preferably in the form of a nonwoven fabric, a film, a mat, a woven fabric, a knitted fabric, or a cloth in which aligned continuous resin fibers are sealed and fixed in shape (so-called NCF: Non-crimp fabric). The form of a nonwoven fabric, which has excellent uniformity of basis weight, is preferred because it can provide a uniform thermoplastic resin layer on the surface of a molded article.

[0057] In a configuration in which the melt viscosity of the thermosetting resin contained in the prepreg is low, the form of a film can be preferably selected. A non-porous film has the advantage that it effectively prevents the thermosetting resin from flowing out of the prepreg onto the surface of the molded article, and a thermoplastic resin layer of high purity can be formed on the surface of the molded article.

[0058] The thermoplastic resin used in the adhesive layer can be at least one selected from polyamide resin, polyester resin, polyphenylene sulfide resin, polyacetal resin, polyphenylene oxide resin, polycarbonate resin, polylactic acid resin, polypropylene resin, thermoplastic polyimide resin including polyimide resin (PI resin) and polyamideimide resin (PAI resin), polyaryletherketone resin including polyetheretherketone resin (PEEK resin) and polyetherketoneketone resin (PEKK resin), aromatic polyethersulfone resin including polysulfone resin (PSU resin), polyethersulfone resin (PES resin) and polyphenylenesulfone resin (PPSU resin), and modified resins thereof. From the viewpoint of achieving both moldability and heat resistance of the molded product, at least one selected from polyamide resin, polyphenylene sulfide resin, polyetherketoneketone resin, and polyetheretherketone resin can be preferably used.

[0059] It is preferable that the adhesive layer contains reinforcing fibers that constitute at least one or both of the reinforcing member and the reinforced member. The presence of both the reinforcing fibers of the reinforcing member and the reinforced member in the adhesive layer reduces stress disturbances within the adhesive layer. As a result, the adhesive layer has fewer high-stress areas, which can be exemplified as a configuration with increased strength at the bonding interface. By preventing fracture at the bonding interface, it is possible to reduce variations in bonding strength.

[0060] In the composite member of the present invention, the thickness of the adhesive layer is preferably 10 μm or more and less than 500 μm. If the adhesive layer is too thin, it may not be able to absorb the difference in shape between the reinforcing member and the reinforced member (so-called dimensional error between the members), which is likely to lead to poor adhesion. Even if the thickness is too thick, the adhesive layer is likely to contain air bubbles, which is one of the causes of increased variation in bonding strength. In terms of increasing the stability of bonding strength, the thickness of the adhesive layer is more preferably 12 μm or more and less than 150 μm, and even more preferably 15 μm or more and less than 50 μm.

[0061] To control the strength and thickness of the adhesive layer, the adhesive layer may contain a filler. Examples of such fillers include fibrous fillers such as glass fiber, milled glass fiber, carbon fiber, potassium titanate whisker, zinc oxide whisker, aluminum borate whisker, aramid fiber, alumina fiber, silicon carbide fiber, ceramic fiber, asbestos fiber, gypsum fiber, and metal fiber; wollastonite, zeolite, sericite, kaolin, mica, clay, pyrophyllite, bentonite, asbestos, talc, and silicates such as alumina silicate; metal compounds such as alumina, silicon oxide, magnesium oxide, zirconium oxide, titanium oxide, and iron oxide; carbonates such as calcium carbonate, magnesium carbonate, and dolomite; sulfates such as calcium sulfate and barium sulfate; hydroxides such as magnesium hydroxide, calcium hydroxide, and aluminum hydroxide; and non-fibrous fillers such as glass beads, ceramic beads, boron nitride, and silicon carbide. These fillers may be hollow, and two or more of these fillers may be used in combination. Furthermore, it is preferable to pre-treat these fibrous or non-fibrous fillers with a coupling agent such as an isocyanate compound, an organic silane compound, an organic titanate compound, an organic borane compound, or an epoxy compound in order to obtain better mechanical properties.

[0062] When such a filler is used to improve strength and dimensional stability, there are no particular restrictions on the amount of filler added, but it is preferable to add 50 to 400 parts by weight per 100 parts by weight of the thermoplastic resin.

[0063] To improve the mechanical properties of the adhesive layer and increase the bonding strength, the adhesive layer may contain a fiber substrate. The fiber substrate is preferably in the form of a woven fabric, knitted fabric, or nonwoven fabric. This type of fiber material has the advantage of being highly shapable, making it less likely to wrinkle when shaped, and highly adaptable to the clearance between the reinforcing material and the reinforced material. The type of fiber in the fiber substrate is not particularly limited, and carbon fiber, glass fiber, aramid fiber, etc. can be used, and a hybrid structure combining these is also possible. [Example]

[0064] The present invention will be specifically explained below with reference to examples, but the present invention is not limited to the descriptions of these examples.

[0065] [Raw materials] Reinforcement fiber: Carbon fiber "TORAYCA" (registered trademark) T800S manufactured by Toray Industries, Inc. Thermosetting resin: Epoxy resin 3900-2. Manufactured by Toray Industries, Inc. Thermoplastic resin: Polyamide 6 resin (melting point 225°C, weight average molecular weight 30,000) manufactured by Toray Industries, Inc.

[0066] [Molding material] Prepreg: A resin film made of epoxy resin 3900-2 was placed on the top and bottom of a fiber substrate made of unidirectionally aligned carbon fiber T800S, and the resin was impregnated into the fiber bundle using the hot melt method to produce a unidirectional prepreg. The prepreg was 0.20 mm thick and had a carbon fiber volume content of 52%. Film adhesive: Thermosetting epoxy adhesive FM-300 manufactured by SOLVAY SA. Sheet-like material: Polyamide 6 resin was press-molded at a resin temperature of 300°C to form a thin film, which was then cooled to room temperature at a cooling rate of 50°C / min to obtain a film. The film had a basis weight of 102 g / m 2 It was.

[0067] Example 1 The prepreg, 30cm square, is [75 / -15] 2s This laminate was placed in a sealing material, and while evacuating, autoclave molding was carried out under conditions of a maximum temperature of T = 180 °C, a pressure of 0.4 MPa, and a holding time of 3 hours to obtain a reinforced member.

[0068] In addition, a 30cm x 25cm square prepreg is [75 / -15] 2sThe laminate was stacked in this order in a hat-shaped forming mold to obtain a hat-shaped laminate with a projected length dimension of 30 cm, a projected width dimension of 150 mm, and an aspect ratio of 2. The laminate had a portion in contact with the adhesive layer at both ends in the projected width direction of the laminate, and the projected width direction dimension of the portion in contact with the adhesive layer was 5 cm at each end. This laminate was placed in a sealing material, and while vacuuming, it was autoclave-molded under conditions of a maximum temperature of T = 180 ° C, a pressure of 0.4 MPa, and a holding time of 3 hours to obtain a reinforcing member.

[0069] The reinforcing member and the reinforced member were overlapped with a film adhesive placed between them to form a molding material. This molding material was placed inside a sealing material, and the two members were bonded together while vacuuming at a maximum temperature of 180°C, a pressure of 0.3 MPa, and a holding time of 1 hour to obtain a composite molded product. When overlapping the reinforcing member and the reinforced member, the reinforcing member and the reinforced member were positioned so that the projected length direction of the reinforcing member matched the orientation angle of the reinforcing fibers in the outermost layer of the reinforced member that was in contact with the adhesive layer. In this case, the formed angle α = 75° and the formed angle β = 75°.

[0070] A four-point bending load was applied to the obtained composite molded product using a testing machine, so that bending deformation occurred in the projected length direction of the reinforcing member until fracture occurred at the joint. After fracture, the composite molded product was observed under a microscope in close proximity to the joint surface, and it was found that the fracture was caused by fracture of the base material of the reinforcing member at the joint surface.

[0071] Furthermore, joint-shaped test pieces were cut out from the resulting composite molded product, with the projected length direction of the reinforcing member as the load direction, and a single lap shear test was performed in accordance with ISO4587-2003. The joint strength was 22 MPa. After fracture, the test piece was observed under a microscope near the joint surface, and it was found that the fracture was due to the base material fracture of the reinforcing member at the joint surface.

[0072] Example 2 The layering order when laminating prepregs to obtain reinforced parts is [30 / -60] 2sThe stacking order for laminating prepregs to obtain reinforcement members is [30 / -60]. 2s The reinforcing member and the reinforced member were prepared in the same manner as in Example 1, and then joined together to obtain a composite molded product in the same manner as in Example 1. At this time, the formed angle α was 30° and the formed angle β was 30°.

[0073] A test piece having a joint shape was cut out from the obtained composite molded product in the same manner as in Example 1, and the joint strength was evaluated to be 20 MPa. After the fracture, the test piece was observed under a microscope in an enlarged scale near the joint surface, and it was found that the fracture at the joint surface was due to the fracture of the base material of the reinforcing member.

[0074] Example 3 The prepreg, 30cm square, is [75 / -15] 2s The laminate was then placed in a mold at an initial mold temperature of Ti=240°C, a pressure of 2.2 MPa, and a pressure holding time of 15 minutes. The laminate was then removed from the mold at a final mold temperature of Te=90°C while maintaining the mold temperature, yielding a reinforced member with the sheet-like material as the adhesive layer.

[0075] In addition, a 30cm x 25cm square sheet was placed in a hat-shaped mold, and similarly, a 30cm x 25cm square prepreg was placed in [75 / -15] 2s The laminate was layered on top of the sheet in this order to obtain a hat-shaped laminate with a projected length of 30 cm, a projected width of 150 mm, and an aspect ratio of 2. The laminate had portions in contact with the adhesive layer at both ends in the projected width direction of the laminate, and the projected width direction dimension of the portions in contact with the adhesive layer was 5 cm at each end. This laminate was placed in a mold and molded under conditions of an initial mold temperature Ti of 240°C, a pressure of 2.2 MPa, and a pressure holding time of 15 minutes. After that, while maintaining the mold temperature, the laminate was removed from the mold at a final mold temperature of Te of 90°C at the time of demolding, to obtain a reinforcing member.

[0076] The reinforcing member and the reinforced member were overlapped so that the surfaces of the thermoplastic resin layer of each member were in contact with each other, and the two members were bonded together at a mold temperature of 250°C, a pressure of 1.0 MPa, and a pressure holding time of 4 minutes to obtain a composite molded product. When overlapping, the reinforcing member and the reinforced member were positioned so that the projected length direction of the reinforcing member matched the orientation angle of the reinforcing fibers in the outermost layer of the reinforced member that was in contact with the adhesive layer. The angle α and angle β were 75°.

[0077] A four-point bending load was applied to the obtained composite molded article in the same manner as in Example 1. After the fracture, the vicinity of the bonded surface of the composite molded article was observed under a microscope at a magnification, and it was found that the fracture was due to the base material fracture of the reinforcing member at the bonded surface. Furthermore, a joint-shaped test piece was cut out from the obtained composite molded article in the same manner as in Example 1, and the bond strength was evaluated, which was found to be 22 MPa. After the fracture, the vicinity of the bonded surface of the test piece was observed under a magnification microscope, and it was found that the fracture was due to the base material fracture of the reinforcing member at the bonded surface.

[0078] Example 4 The layering order when laminating prepregs to obtain reinforced parts is [30 / -60] 2s The stacking order for laminating prepregs to obtain reinforcement members is [30 / -60]. 2s The reinforcing member and the reinforced member were prepared in the same manner as in Example 3, and then joined together to obtain a composite molded product in the same manner as in Example 3. At this time, the formed angle α was 30° and the formed angle β was 30°.

[0079] A test piece having a joint shape was cut out from the obtained composite molded product in the same manner as in Example 1, and the joint strength was evaluated to be 20 MPa. After the fracture, the test piece was observed under a microscope in an enlarged scale near the joint surface, and it was found that the fracture at the joint surface was due to the fracture of the base material of the reinforcing member.

[0080] Comparative Example 1 The layering order when laminating prepregs to obtain reinforced components is [20 / -70] 2s The stacking order for laminating prepregs to obtain reinforcement members is [20 / -70]. 2sThe reinforcing member and the reinforced member were prepared in the same manner as in Example 1, and then joined together to obtain a composite molded product in the same manner as in Example 1. At this time, the formed angle α was 20° and the formed angle β was 20°.

[0081] A test piece having a joint shape was cut out from the obtained composite molded product in the same manner as in Example 1, and the bond strength was evaluated to be 24 MPa. After the fracture, the test piece was observed under a microscope in the vicinity of the bonded surface, and it was found that the fracture occurred due to cohesive failure of the adhesive layer at the bonded surface.

[0082] Comparative Example 2 The layering order when laminating prepregs to obtain reinforced components is [5 / -85] 2s The stacking order for laminating prepregs to obtain reinforcement members is [5 / -85]. 2s The reinforcing member and the reinforced member were prepared in the same manner as in Example 1, and then joined together to obtain a composite molded product in the same manner as in Example 1. At this time, the formed angle α was 5° and the formed angle β was 5°.

[0083] A test piece having a joint shape was cut out from the obtained composite molded product in the same manner as in Example 1, and the bond strength was evaluated to be 28 MPa. After the fracture, the test piece was observed under a microscope in the vicinity of the bonded surface, and it was found that the fracture occurred due to cohesive failure of the adhesive layer at the bonded surface.

[0084] Comparative Example 3 The layering order when laminating prepregs to obtain reinforced components is [20 / -70] 2s The stacking order for laminating prepregs to obtain reinforcement members is [20 / -70]. 2s The reinforcing member and the reinforced member were prepared in the same manner as in Example 3, and then joined together to obtain a composite molded product in the same manner as in Example 3. At this time, the formed angle α was 20° and the formed angle β was 20°.

[0085] A test piece having a joint shape was cut out from the obtained composite molded product in the same manner as in Example 1, and the bond strength was evaluated to be 30 MPa. After the fracture, the test piece was observed under a microscope in the vicinity of the bonded surface, and it was found that the fracture occurred due to cohesive failure of the adhesive layer at the bonded surface.

[0086] Comparative Example 4 The layering order when laminating prepregs to obtain reinforced components is [5 / -85] 2s The stacking order for laminating prepregs to obtain reinforcement members is [5 / -85]. 2s The reinforcing member and the reinforced member were prepared in the same manner as in Example 3, and then joined together to obtain a composite molded product in the same manner as in Example 3. At this time, the formed angle α was 5° and the formed angle β was 5°.

[0087] A test piece having a joint shape was cut out from the obtained composite molded product in the same manner as in Example 1, and the bond strength was evaluated to be 44 MPa. After the fracture, the test piece was observed under a microscope in an enlarged scale near the bonded surface, and it was found that the fracture occurred due to cohesive failure of the adhesive layer at the bonded surface. [Explanation of symbols]

[0088] 1: Reinforcement member 1 2: Longitudinal direction of the projected length of the reinforcing member 1 3: The outermost layer in contact with the adhesive layer of the reinforcing member 1 4: Orientation direction of reinforcing fibers in the outermost layer in contact with the adhesive layer of the reinforcing member 1 5: Angle α between the longitudinal direction of the projected length of the reinforcing member 1 and the orientation direction of the reinforcing fibers in the outermost layer in contact with the adhesive layer of the reinforcing member 1 6: Angle β between the longitudinal direction of the projected length of the reinforcing member 1 and the orientation direction of the reinforcing fibers in the outermost layer that contacts the adhesive layer of the reinforced member 11: Reinforcement member 2 12: Longitudinal direction of the projected length of the reinforcing member 2 13: The outermost layer in contact with the adhesive layer of the reinforcing member 2 14: Orientation direction of reinforcing fibers in the outermost layer in contact with the adhesive layer of the reinforcing member 2 15: Angle α between the longitudinal direction of the projected length of the reinforcing member 2 and the direction of the reinforcing fibers of the outermost layer in contact with the adhesive layer of the reinforcing member 2 16: Angle β between the longitudinal direction of the projected length of the reinforcing member 2 and the orientation direction of the reinforcing fibers in the outermost layer in contact with the adhesive layer of the reinforced member 21: Reinforced member 22: Orientation direction of reinforcing fibers in reinforced member 31: Reinforcement member 3 having an in-plane bent shape 32: Projected shape of the reinforcing member 3 as viewed from above 33: Approximate dimension of the projected length of the reinforcing member 3 34: Approximate dimension of projected width of reinforcing member 3 35: Longitudinal direction of the projected length of the reinforcing member 3 36: Orientation direction of reinforcing fibers in the outermost layer in contact with the adhesive layer of the reinforcing member 3 37: Angle α between the longitudinal direction of the projected length of the reinforcing member 3 and the orientation direction of the reinforcing fibers in the outermost layer in contact with the adhesive layer of the reinforcing member 3 41: Reinforcement member 4 with out-of-plane bending shape 42: Projected shape of reinforcing member 4 as viewed from above 43: Approximate dimension of the projected length of the reinforcing member 4 44: Approximate dimension of projected width of reinforcing member 4 45: Longitudinal direction of the projected length of the reinforcing member 4 46: Orientation direction of reinforcing fibers in the outermost layer in contact with the adhesive layer of the reinforcing member 4 47: Angle α between the longitudinal direction of the projected length of the reinforcing member 4 and the orientation direction of the reinforcing fibers of the outermost layer in contact with the adhesive layer of the reinforcing member 3 48: A portion of the outermost layer of the reinforcing member 4 that is in contact with the adhesive layer and is parallel to the xy plane 49: A portion of the outermost layer of the reinforcing member 4 that is in contact with the adhesive layer and is parallel to the x'y' plane [Industrial Applicability]

[0089] The composite member of the present invention has high load-bearing performance and stable bonding strength, and therefore can be suitably used in mobile objects including aircraft, sports applications, and electronic device housings, which require reliability.

Claims

1. A composite component in which a reinforcing member having an aspect ratio greater than 1 and smaller than 1,000,000,000 according to the following formula (1) is joined to a reinforced member via an adhesive layer, wherein the adhesive layer contains reinforcing fibers that constitute at least one or both of the reinforcing member and the reinforced member, and a part or all of the outermost layer of the reinforcing member that contacts the adhesive layer is made of a unidirectional prepreg containing reinforcing fibers and a thermosetting resin, and the angle α between the orientation direction of the reinforcing fibers of the unidirectional prepreg and the longitudinal direction of the projected length of the reinforcing member in a top view is 30°≦α<90°. Aspect ratio = Projected length of reinforcing member (m) / Projected width of reinforcing member (m) (1)

2. A composite component in which a reinforcing member having an aspect ratio greater than 1 and smaller than 1,000,000,000 according to the following formula (1) is joined to a reinforced member via an adhesive layer, wherein the adhesive layer contains reinforcing fibers that constitute at least one or both of the reinforcing member and the reinforced member, and a part or all of the outermost layer of the reinforced member that contacts the adhesive layer is made of a unidirectional prepreg containing reinforcing fibers and a thermosetting resin, and the angle β formed between the orientation direction of the reinforcing fibers of the unidirectional prepreg and the longitudinal direction of the projected length of the reinforcing member in a top view is 30°≦β<90°. Aspect ratio = Projected length of reinforcing member (m) / Projected width of reinforcing member (m) (1)

3. A composite member in which a reinforcing member having an aspect ratio according to the following formula (1) greater than 1 and less than 1,000,000,000 is joined to a reinforced member via an adhesive layer, wherein part or all of the outermost layer of the reinforcing member in contact with the adhesive layer is made of a unidirectional prepreg containing reinforcing fibers and a thermosetting resin, and the angle α between the orientation direction of the reinforcing fibers of the unidirectional prepreg and the longitudinal direction of the projected length of the reinforcing member in a top view satisfies 30°≦α<90°, and part or all of the outermost layer in contact with the adhesive layer of the reinforced member to which the reinforcing member is joined is made of a unidirectional prepreg containing reinforcing fibers and a thermosetting resin, and the angle β between the orientation direction of the reinforcing fibers of the unidirectional prepreg and the longitudinal direction of the projected length of the reinforcing member in a top view satisfies 30°≦β<90°. Aspect ratio = Projected length of reinforcing member (m) / Projected width of reinforcing member (m) (1)

4. 4. The composite member according to claim 1, wherein the adhesive layer is made of a thermosetting resin.

5. 5. The composite material according to claim 4, wherein the thermosetting resin is at least one selected from the group consisting of epoxy resin, benzoxazine resin, cyanate ester resin, bismaleimide resin, and phenolic resin.

6. The composite member according to any one of claims 1 to 3, wherein the adhesive layer is made of a thermoplastic resin.

7. 7. The composite member according to claim 6, wherein the thermoplastic resin is at least one selected from the group consisting of polyamide resin, polyphenylene sulfide resin, polyether ketone ketone resin, and polyether ether ketone resin.

8. 4. The composite member according to claim 3, wherein the adhesive layer contains reinforcing fibers that constitute at least one of the reinforcing member and the reinforced member.

9. The adhesive layer according to any one of claims 1 to 8, wherein the thickness of the adhesive layer is 10 µm or more and less than 500 µm. Composite material.

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