Fiber-reinforced composite member and composite body

Abstract

To provide a fiber-reinforced resin composite member which is integrated with another member without separately providing a film.SOLUTION: A fiber-reinforced composite member includes an outer layer part and an inner layer part. The outer layer part is composed of a first fiber-reinforced composite material containing a reinforcement fiber base material and a thermoplastic epoxy resin, and has a bonding scheduled position where it is bonded to other member. The inner layer part is composed of a second fiber-reinforced composite material containing a reinforcement fiber base material and a matrix resin. Tensile shear strength obtained by measuring a bonded test piece manufactured by locally bonding the bonding scheduled position of the fiber-reinforced composite member and a sample of the other member by heat welding according to ASTM D 3165 is 15 MPa or more.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a fiber-reinforced composite member that is composed of a fiber-reinforced composite material that contains a reinforcing fiber substrate and a matrix resin. [Background technology]

[0002] Fiber-reinforced composite materials, which use thermosetting or thermoplastic resins as a matrix resin and combine them with reinforcing fiber substrates such as carbon fiber or glass fiber, are lightweight yet have excellent mechanical properties such as strength and rigidity, and are therefore used in many fields, including automobiles, railway vehicles, ships, civil engineering and construction, sporting goods, and electronic devices.

[0003] However, these fiber-reinforced composite materials are not suitable for applications in which parts or structures having complex shapes are manufactured in a single molding process, and when applying fiber-reinforced composite materials to such applications, it is often necessary to integrate the fiber-reinforced composite material with other members of the same or different types.

[0004] As an example of a fiber-reinforced composite material composite formed by integrating a fiber-reinforced composite material with another member, Patent Document 1 discloses a composite in which a fiber-reinforced composite material and another member are integrally bonded via a coating made of a thermoplastic resin composition. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 4543696 Summary of the Invention [Problem to be solved by the invention]

[0006] As described above, in the composite of Patent Document 1, a coating made of a thermoplastic resin composition is provided separately from a fiber-reinforced composite material, and the fiber-reinforced composite material is integrated with other members via this coating.

[0007] An object of the present invention is to provide a fiber-reinforced resin composite member that can be integrated with other members without providing a separate coating. [Means for solving the problem]

[0008] In order to solve the above problems, the present invention provides (1) a fiber-reinforced composite member having an outer layer and an inner layer. The outer layer is made of a first fiber-reinforced composite material containing a reinforcing fiber base material and a thermoplastic epoxy resin, and has a planned joining location for joining to another member. The inner layer is made of a second fiber-reinforced composite material containing a reinforcing fiber base material and a matrix resin. A joint test piece is prepared by locally joining the planned joining location of the fiber-reinforced composite member and a sample of the other member by thermal welding, and the tensile shear strength measured in accordance with ASTM D 3165 is 15 MPa or more.

[0009] (2) The fiber-reinforced composite member according to (1), wherein the matrix resin contained in the second fiber-reinforced composite material is selected from a thermosetting resin having a bisphenol structure in its main skeleton and an amorphous thermoplastic resin.

[0010] (3) A fiber-reinforced composite member as described in (2), wherein the outer layer portion is constructed by laminating sheet materials made of the first fiber-reinforced composite material, and the inner layer portion is constructed by laminating sheet materials made of the second fiber-reinforced composite material.

[0011] (4) A fiber-reinforced composite member according to (1), wherein the other member is a metal member, a resin member or another fiber-reinforced composite member.

[0012] (5) A fiber-reinforced composite member according to (2), wherein the other member is a metal member, a resin member or another fiber-reinforced composite member.

[0013] (6) A fiber-reinforced composite member according to (3), wherein the other member is a metal member, a resin member or another fiber-reinforced composite member.

[0014] (7) A composite body formed by joining the intended joining portion of the fiber-reinforced composite member according to any one of (1) to (6) and the other member by thermal welding. Effect of the Invention

[0015] The fiber-reinforced resin composite member according to the present invention can be integrated with other members with sufficient strength without the need for a separate coating. [Brief description of the drawings]

[0016] [Figure 1] 1 is a schematic cross-sectional view showing the configuration of a fiber-reinforced composite member 1 according to the present invention. [Diagram 2] FIG. 1 is a schematic cross-sectional view showing the configuration of a composite 3 according to the present invention. [Diagram 3] 1 is an SEM photograph (2000x) of the bonded portion between pyrofil and the CFRTP prepreg "NS-TEPreg" in the test piece of Example 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] (Configuration of fiber reinforced composite member 1) First, the configuration of a fiber-reinforced composite member 1 according to the present invention will be described. FIG. 1 is a schematic cross-sectional view showing the configuration of a fiber-reinforced composite member 1 according to the present invention. Referring to FIG. 1, the fiber-reinforced composite member 1 includes an outer layer portion 11 and an inner layer portion 12. The outer layer portion 11 contains a reinforcing fiber base material and a thermoplastic epoxy resin. The inner layer portion 12 contains a reinforcing fiber base material and a matrix resin. The outer layer portion 11 includes a planned joining portion 110 that is a portion that is planned to be joined to another member 2 (described later). The "planned joining portion" includes not only a surface that comes into contact with the other member 2, but also a portion that is physically joined to the other member 2 by joining by thermal welding or the like, but does not exclude chemical bonding.

[0018] The reinforcing fibers used in the outer layer 11 and the inner layer 12 may be ceramic-based inorganic fibers such as pitch, PAN, glass fiber, aramid fiber, basalt fiber, and alumina fiber; organic fibers such as aramid, vinylon, PBO fiber, ultra-high molecular weight polyethylene resin, and high-strength polyarylate resin; and cellulose-based natural fibers such as jute, cotton, and kenaf. The reinforcing fibers used in the outer layer 11 and the reinforcing fibers used in the inner layer 12 may be the same type or different types. These reinforcing fibers may be used alone or in combination.

[0019] The form of the reinforcing fiber substrate used in the outer layer 11 and the inner layer 12 is not particularly limited, and any of continuous fiber substrates such as cloth materials and unidirectional materials (UD materials) and short fiber substrates such as random mat materials and felt materials can be used. The reinforcing fiber substrate used in the outer layer 11 and the inner layer 12 is preferably a random mat material or continuous fiber substrate in which the reinforcing fibers are strongly oriented in the planar direction and therefore springback is unlikely to occur when heat is applied, and most preferably a continuous fiber substrate.

[0020] Here, methods for heat welding components together are roughly divided into local joining and extensive joining. "Local joining" means joining by heating only a part of the components, and examples thereof include vibration welding using ultrasonic waves or high frequency waves, and welding using a hot plate, heat gun, or laser. By performing local joining between the intended joining point 110 of the fiber-reinforced composite component 1 and another component 2, the fiber-reinforced composite component 1 and the other component 2 are joined. "Extensive joining" means joining in which the entire component is uniformly heated by a large device, and examples thereof include welding using a heat press machine. Both local joining and extensive joining are widely used as heat welding methods. However, the joining strength by local joining is smaller than that by extensive joining, and therefore the joining may be insufficient. In view of the above, the present inventors conducted extensive research into an index of bonding strength in thermal welding between a fiber-reinforced composite member 1 and another member 2. As a result, they concluded that even in a test piece produced by locally bonding a sample of a fiber-reinforced composite member 1 and another member 2, if the tensile shear strength measured by a method in accordance with ASTM D 3165 is 15 MPa or more, the tensile shear strength is equal to or greater than that of a test piece produced using a heat press machine, and therefore sufficient bonding strength is achieved regardless of whether the bonding is local or extensive. In order to achieve the above index, the present inventors further studied the matrix resin of the outer layer portion 11 that is directly bonded to the other member 2. As a result, they came to the conclusion that in order to achieve the above index, it is necessary to adopt a thermoplastic epoxy resin as the matrix resin of the outer layer portion 11. Thermoplastic epoxy resin refers to a phenoxy resin obtained by polymerizing a raw material compound in situ among phenoxy resins produced without a solvent, and is also expressed as an in situ polymerization type phenoxy resin. Examples of the in situ polymerization type phenoxy resin include those manufactured by Nippon Steel Chemical & Material Co., Ltd. (matrix resin for NS-TEPreg) and Nagase ChemteX Corporation (polymerization product of main agent: DENATITE XNR6850V and curing agent: DENATITE XNH6850V).

[0021] Usually, local bonding requires smaller equipment and can be performed in a shorter time than extensive bonding. However, as described above, the bonding strength of local bonding is smaller than that of extensive bonding, and the bonding may be insufficient. In contrast, the fiber-reinforced composite member 1 according to the present invention achieves the above index, and therefore, even when the fiber-reinforced composite member 1 is bonded to another member 2 by local bonding to form a composite member 3 (described later), it is considered that a bonding strength equal to or greater than that of extensive bonding can be achieved. Note that this description indicates that local bonding may be adopted for bonding the fiber-reinforced composite member 1 to another member 2, and does not prevent extensive bonding from being adopted for bonding the fiber-reinforced composite member 1 to another member 2.

[0022] Patent Document 1 discloses a configuration in which a coating is further provided on the surface of a fiber-reinforced composite material, and the fiber-reinforced composite material is integrated with another member via this coating. In contrast, the fiber-reinforced composite member 1 of the present invention does not take the trouble of providing a coating separately from the fiber-reinforced composite member, but rather directly bonds the fiber-reinforced composite member 1 itself to another member 2 to integrate them, which is a completely different technical concept.

[0023] The shape of the surface of the intended joining portion 110 of the outer layer portion 11 (the surface that comes into contact with another component 2) is not particularly limited to a horizontal surface, but may be processed into a shape having protrusions, for example, in order to further increase the joining strength with the other component 2.

[0024] The weight average molecular weight of the thermoplastic epoxy resin contained in the outer layer portion 11 is not particularly limited, but is, for example, 6,000 or more.

[0025] The matrix resin used in the inner layer portion 12 is not particularly limited, and may be selected from, for example, a thermosetting resin having a bisphenol structure in the main skeleton and an amorphous thermoplastic resin. Examples of the thermosetting resin having a bisphenol structure in the main skeleton include thermosetting epoxy resins. Examples of the amorphous thermoplastic resin include phenoxy resins such as YP-50, YP-50S, YP-55U (bisphenol A type), Phenototo FX-316 (bisphenol F type), YP-70 (copolymerization type of bisphenol A and bisphenol F), Phenototo YPB-43C, and FX293 (special phenoxy resin) (all manufactured by Nippon Steel Chemical & Material Co., Ltd.), polycarbonate resins such as Iupilon S3000 and Novalex 7022R (manufactured by Mitsubishi Engineering Plastics Co., Ltd.), and polyarylate resins such as U-8000 (manufactured by Unitika Co., Ltd.).

[0026] The method of constructing the outer layer portion 11 and the inner layer portion 12 is not particularly limited. For example, the outer layer portion 11 may be configured by laminating a plurality of sheet materials of a first fiber-reinforced composite material containing a reinforcing fiber base material and a thermoplastic epoxy resin, and the inner layer portion 12 may be configured by laminating a plurality of sheet materials of a second fiber-reinforced composite material containing a reinforcing fiber base material and a predetermined matrix resin. In this case, a prepreg of the outer layer portion 11 is prepared by laminating a plurality of sheet materials of the first fiber-reinforced composite material, a prepreg of the inner layer portion 12 is prepared by laminating a plurality of sheet materials of the second fiber-reinforced composite material, and these are stacked and integrated (bonded) to form a fiber-reinforced composite member 1 in which the outer layer portion 11 and the inner layer portion 12 are bonded. As a method of integration (bonding), for example, a known bonding method such as a method using an autoclave or a heat press machine, a vacuum bag method, or pultrusion molding can be adopted.

[0027] The form of the bonding surface between the outer layer portion 11 and the inner layer portion 12 is not particularly limited and may be smooth or rough, but it is preferable to form projections and recesses before bonding. This creates an anchor effect, which can further increase the bonding strength between the outer layer portion 11 and the inner layer portion 12.

[0028] Also, for example, a fiber-reinforced composite member 1 composed of an outer layer 11 and an inner layer 12 can be formed by impregnating a predetermined portion of a single reinforcing fiber substrate with a thermoplastic epoxy resin and impregnating the other portion with a predetermined matrix resin, followed by molding. In this case, the integration step (bonding step) of integrating (bonding) the outer layer 11 and the inner layer 12 can be omitted.

[0029] The Vf (fiber volume fraction) of the outer layer portion 11 is not particularly limited, but is within the range of 40% or more and less than 60%, for example, and the difference between the Vf of the outer layer portion 11 and the Vf of the inner layer portion 12 is desirably 5-10. Furthermore, the Vf of the intended joining locations 110 in the outer layer portion 11 is preferably equal to or less than the Vf of the inner layer portion 12. The fiber-reinforced composite member 1 and the other member 2 are joined by entanglement due to diffusion of matrix resin at the joining interface of the intended joining locations 110 in the outer layer portion 11. Since a smaller Vf results in a relatively larger amount of matrix resin, by setting the Vf of the intended joining locations 110 to be equal to or less than the Vf of the inner layer portion 12, the amount of matrix resin at the intended joining locations 110 can be relatively increased, and the amount of entanglement of the resin due to diffusion at the joining interface can be increased, thereby further increasing the joining strength.

[0030] (Complex 3 composition) Next, the configuration of the composite 3 formed by joining the fiber-reinforced composite member 1 to another member 2 will be described below. Fig. 2 is a schematic cross-sectional view showing the configuration of the composite 3 according to the present invention. With reference to Fig. 2, the other member 2 is joined to a planned joining location 110 in the outer layer portion 11, so that it is formed integrally with the fiber-reinforced composite member 1, and the composite 3 is constituted.

[0031] As described above, heat welding is used to join the outer layer portion 11 and the other member 2. As a heat welding method for the present invention, in addition to the conventional wide-ranging joining (such as welding using a press and a mold, or welding by injection molding), local joining can also be adopted. The present invention is particularly suitable for local joining.

[0032] The other member 2 can be appropriately selected depending on the application, and may be, for example, a metal member, a resin member, or another fiber-reinforced composite member.

[0033] In a state in which the fiber-reinforced composite member 1 is joined to another member 2 (in the state of the composite member 3), the weight average molecular weight of the thermoplastic epoxy resin in the portion of the outer layer 11 that is joined to the other member 2 is not particularly limited as long as it is at least 6,000 or more, but it is preferably 40,000 or more.

[0034] (Example) The present invention will now be described in more detail with reference to examples.

[0035] Example 1 In Example 1, three layers of CFRTP prepreg "NS-TEPreg" (registered trademark) (corresponding to the above-mentioned outer layer 11) were overlaid with nine layers of Pyrofil (registered trademark) (manufactured by Mitsubishi Chemical Corporation, CFRP epoxy) (corresponding to the above-mentioned inner layer 12), and molding was performed using an autoclave under molding conditions of a temperature of 160°C and a holding time of 3 hours to obtain a fiber-reinforced composite member (corresponding to the above-mentioned fiber-reinforced composite member 1). The CFRTP prepreg "NS-TEPreg" used in Example 1 has reinforcing fibers as PAN-based carbon fibers (manufactured by Toray Industries, Inc., T700SC-12K-60E), a matrix resin as in-situ polymerized phenoxy resin, and a fiber weight per unit area of ​​150 g / m. 2 , Rc (resin content): 35%. Pyrofil is a cross prepreg with PAN-based carbon fiber reinforcement and thermosetting epoxy resin matrix, with a fiber weight of 150 g / m 2 , Rc (resin content): 33% UD prepreg.

[0036] Next, the obtained fiber reinforced composite member and TEPEX (registered trademark) 202 (manufactured by Bond Laminates) CFRTP nylon 6 (corresponding to the above-mentioned other member 2) were ultrasonically welded and integrated using an ultrasonic welding device DΣG2210 (manufactured by Seidensha Electronics Co., Ltd.) to obtain a joint (corresponding to the above-mentioned composite 3), and a test piece was produced from this joint. The ultrasonic welding was performed using the ultrasonic welding device DΣG2210 with an oscillation frequency of 19.15 kHz (longitudinal vibration), lap = 12.5 mm, control method: time control, speed = 250, hold time = 10 s, and vibration time of 4 s.

[0037] Example 2 In Example 2, a test piece was prepared in the same manner as in Example 1, except that 9 layers of GFRTP prepreg "NS-TEPreg" were used as the fiber-reinforced composite material corresponding to the above-mentioned outer layer portion 11. The GFRTP prepreg "NS-TEPreg" used in Example 2 has glass fiber (manufactured by Nitto Boseki Co., Ltd.) as reinforcing fiber, in-situ polymerization type phenoxy resin as matrix resin, and fiber basis weight: 80 g / m 2, Rc (resin content): 40% UD prepreg.

[0038] Comparative Example 1 In Comparative Example 1, a test piece was prepared in the same manner as in Example 1, except that one layer of the CFRTP prepreg “NS-TEPreg” of Example 1 was used as the fiber-reinforced composite material corresponding to the outer layer 11 described above, and 12 layers of the pyrofil of Example 1 were used as the fiber-reinforced composite material corresponding to the inner layer 12 described above.

[0039] Comparative Example 2 In Comparative Example 2, a test piece was prepared in the same manner as in Example 1, except that one layer of the GFRTP prepreg “NS-TEPreg” of Example 2 was used as the fiber-reinforced composite material corresponding to the outer layer portion 11 described above, and 13 layers of the pyrofil of Example 1 were used as the fiber-reinforced composite material corresponding to the inner layer portion 12 described above.

[0040] The test pieces obtained in Examples 1 and 2 and Comparative Examples 1 and 2 were subjected to a tensile shear test in accordance with ASTM D 3165 to identify the location of breakage and to measure the tensile shear strength.

[0041] The experimental conditions and test results for each of the examples and comparative examples are shown in Table 1.

[0042] [Table 1]

[0043] The tensile shear strength (18 MPa) measured on the test piece of Example 1 and the tensile shear strength (16 MPa) measured on the test piece of Example 2 were both 15 MPa or more. Furthermore, in the tensile shear tests of Examples 1 and 2, the CFRTP nylon 6 itself was destroyed, but the bonding surface between the fiber reinforced composite member and the CFRTP nylon 6 was not destroyed. Therefore, it was found that in Examples 1 and 2, the fiber reinforced composite member and the CFRTP nylon 6 were bonded with sufficient strength.

[0044] On the other hand, the tensile shear strength (6 MPa) measured for the test piece of Comparative Example 1 and the tensile shear strength (10 MPa) measured for the test piece of Comparative Example 2 were both less than 15 MPa. Furthermore, in the tensile shear tests of Comparative Example 1 and Comparative Example 2, the bonding surface between the fiber reinforced composite member and CFRTP nylon 6 was destroyed. Therefore, it was found that the bonding strength between the fiber reinforced composite member and CFRTP nylon 6 was insufficient in Comparative Example 1 and Comparative Example 2.

[0045] Here, for the test piece of Example 1, the interface of the adhesion part between the pyrofil and the CFRTP prepreg "NS-TEPreg" was observed in a cross-sectional view at 2000 times magnification using a scanning electron microscope (SEM). Specifically, using IT500-HR (manufactured by JEOL Ltd.), the measurement mode was set to "backscattered electron image", and measurements were performed at an acceleration voltage of 10 kV and a current value of 80. Before the observation, Os vapor deposition was performed to impart conductivity.

[0046] An SEM photograph (2000x magnification) of the bonded portion between the pyrofil and the CFRTP prepreg "NS-TEPreg" in the test piece of Example 1 is shown in Figure 3. Referring to Figure 3, no interface was observed between the pyrofil and the CFRTP prepreg "NS-TEPreg". In addition, in the SEM photograph (2000x magnification) of the bonded portion between the pyrofil and the GFRTP prepreg "NS-TEPreg" in the test piece of Example 2, no interface was observed between the pyrofil and the GFRTP prepreg "NS-TEPreg", as in Figure 3.

[0047] The present invention is not limited to the above-described embodiments as long as the gist of the present invention is not exceeded. [Explanation of symbols]

[0048] 1: fiber-reinforced composite member 2: other member 3: composite member 11: outer layer 12: inner layer

Claims

1. A fiber-reinforced composite member having an outer layer portion and an inner layer portion, The outer layer portion is made of a first fiber-reinforced composite material containing a reinforcing fiber substrate and a thermoplastic epoxy resin, and has a joining portion to be joined to another member, The inner layer portion is composed of a second fiber reinforced composite material containing a reinforcing fiber substrate and a matrix resin, A joint test piece prepared by locally joining the intended joining portion of the fiber-reinforced composite member and a sample of the other member by thermal welding has a tensile shear strength of 15 MPa or more as measured in accordance with ASTM D 3165. A fiber-reinforced composite member.

2. The matrix resin contained in the second fiber reinforced composite material is selected from a thermosetting resin having a bisphenol structure in the main skeleton and an amorphous thermoplastic resin. A fiber-reinforced composite member according to claim 1 .

3. The outer layer portion is configured by laminating sheet materials made of the first fiber-reinforced composite material, The inner layer portion is configured by laminating sheet materials made of the second fiber-reinforced composite material. A fiber-reinforced composite member according to claim 2 .

4. 2. The fiber-reinforced composite member according to claim 1, wherein the other member is a metal member, a resin member or another fiber-reinforced composite member.

5. 3. The fiber-reinforced composite member according to claim 2, wherein the other member is a metal member, a resin member or another fiber-reinforced composite member.

6. 4. The fiber-reinforced composite member according to claim 3, wherein the other member is a metal member, a resin member or another fiber-reinforced composite member.

7. The fiber-reinforced composite member according to any one of claims 1 to 6 is formed by joining the intended joining portion of the fiber-reinforced composite member and the other member by thermal welding. A complex characterized by:

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