Laminated composite

Abstract

[Problem] The purpose of the present invention is to provide a layered composite that has high levels of both flexural modulus and moldability. [Solution] A layered composite, characterized in comprising a carbon-fiber-reinforced resin in which a chopped strand prepreg, obtained by impregnating a resin with carbon fiber, is oriented so as to exhibit pseudo-isotropic properties, and a steel plate that is layered on at least one surface of the carbon-fiber-reinforced resin and has a tensile breakage elongation φ of 20% or higher, the flexural modulus of a flat plate obtained in compliance with ASTM D-790 being at least 30 GPa.

Description

Technical Field

[0001] The present invention relates to a laminated composite of carbon fiber reinforced resin and metal.

Background Art

[0002] Conventionally, it has been known that carbon fiber reinforced resin is used as automobile parts, housings of electronic devices, etc. Such carbon fiber reinforced resin has both high strength and moldability, and a molded body is manufactured by a die pressing method, an autoclave method, or the like.

[0003] For example, Patent Document 1 discloses an isotropic carbon fiber reinforced resin manufactured by arranging prepregs randomly, laminating them, and heating and processing them. Such carbon fiber reinforced resin generally has characteristics such as being moldable in a short time, being capable of secondary processing, or being easily recyclable. Due to these characteristics, it has begun to attract attention for use in members of automobiles and electronic devices that require a large production quantity at a relatively low cost and have complex shapes.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Patent Document 6

Summary of the Invention

Problems to be Solved by the Invention

[0005] On the one hand, the carbon fiber reinforced resin as described in Patent Document 1 above had both strength and moldability, but there were still problems with the elastic modulus as another important parameter.

[0006] That is, the carbon fiber reinforced resin using chopped fibers as described in Patent Document 1 had a certain degree of strength and moldability by itself, but it was difficult to significantly improve the elastic modulus while maintaining isotropy with only such a carbon fiber reinforced resin. On the other hand, carbon fiber reinforced resins that do not have isotropy, such as the continuous fibers described above, have problems with moldability, such as being unable to perform complex molding in the first place.

[0007] In recent years, as composite materials have been developed for various applications, development of composite materials in which a metal and a fiber reinforced resin are joined has also been underway. For example, Patent Documents 2 to 6 disclose techniques for laminating a metal material such as a steel plate or aluminum and a fiber reinforced resin with or without an adhesive or the like. In any of these techniques, a composite material in which a metal and a fiber reinforced resin are joined is provided for the purpose of improving specific rigidity and specific strength, or for the purpose of weight reduction and strength improvement.

[0008] As described above, an object of the present invention is to provide a laminated composite body that shares high flexural elastic modulus and moldability in a laminated composite material in which a metal and a carbon fiber reinforced resin are laminated. In particular, in a laminated composite body having an isotropic carbon fiber reinforced resin in which carbon fibers are impregnated with a thermoplastic resin, and a metal material (steel plate) laminated on at least one surface of the carbon fiber reinforced resin, an object is to provide a laminated composite body having a high flexural elastic modulus, and to provide a molded body having a high flexural elastic modulus using the laminated composite body.

Means for Solving the Problems

[0009] The laminated composite body of the present embodiment is (1) carbon fiber is thermoplastic resin inside impregnated it chopped strand prepregis Suspected isotropy shows Oriented as if caused A carbon fiber reinforced resin and a steel plate laminated on at least one surface of the carbon fiber reinforced resin, wherein the tensile fracture elongation φ is 20% or more contains Laminated composite wherein The flexural modulus of elasticity of the flat plate obtained in accordance with ASTM D-790 is 30 GPa or more the specific flexural modulus of the laminate composite obtained by dividing the flexural modulus by the specific gravity of the laminate composite is 20 GPa or more Characterized by 。 The laminated composite of the present embodiment is the above (1 ) to In, ( 2 ) The thickness ratio of the steel plate to the total thickness of the laminated composite is preferably 1% to 20%. The laminated composite of the present embodiment is the above (1) or (2) In, ( 3 ) The steel plate preferably has a value S of 7.5 or more. However, S [mm] =(Steel plate thickness t [mm] ×Tensile fracture elongation φ) / (Friction coefficient μ of steel plate) where φ is preferably expressed in %. The laminated composite of the present embodiment is any of the above (1) to ( 3 ) In, ( 4 ) The steel plate is preferably a surface-treated steel plate, and the surface treatment is preferably plating containing Zn or Ni 。

Effect of the Invention

[0010] According to the present invention, in a composite material in which a steel plate and a carbon fiber reinforced resin are laminated, it is possible to provide a laminated composite and a molded body having a high flexural modulus of elasticity

Brief Description of the Drawings

[0011] [Fig. 1] It is a schematic diagram showing a cross section of the laminated composite 10 of the present embodiment [Fig. 2] It is a schematic diagram for showing an example of a mold for manufacturing the molded body 20 of the present embodiment [Fig. 3]It is a partial enlarged view for showing an example of a mold for manufacturing the molded body 20 of the present embodiment.

Mode for Carrying Out the Invention

[0012] ≪Laminated Composite 10≫ Hereinafter, embodiments for carrying out the present invention will be described. FIG. 1 is a diagram schematically showing a laminated composite according to the present embodiment. The laminated composite 10 of the present embodiment is used for automobile members, electronic device members, etc. The laminated composite 10 of the present embodiment may be used as a flat plate, or may be subjected to molding such as press molding under heating and / or pressure.

[0013] As shown in FIG. 1, the laminated composite 10 of the present embodiment includes a carbon fiber reinforced resin 110 and a steel plate 120 laminated on at least one surface of the carbon fiber reinforced resin 110. In FIG. 1, the steel plate 120 has a two-layer structure laminated on one side of the above-described carbon fiber reinforced resin 110, but the present invention is not limited thereto. That is, steel plates 120 may be laminated on both surfaces of the carbon fiber reinforced resin 110 to form a three-layer structure. Also, a multilayer structure in which the carbon fiber reinforced resin 110 and the steel plate 120 are alternately laminated may be formed.

[0014] The laminated composite 10 in the present embodiment is characterized in that the flexural modulus of elasticity in a flat plate is 30 GPa or more. The reason is as follows. That is, generally, when manufacturing a molded body using a carbon fiber reinforced resin, since secondary processing is possible as an advantage of the thermoplastic resin, press molding using a press mold is often performed on a flat carbon fiber reinforced resin. However, when the present inventors manufacture a molded body by the above method, it has been found that, as a demerit of secondary processing, the flexural modulus of elasticity of the molded body is lower than that of a flat plate.

[0015] On the one hand, for example, in an electronic device housing that protects precision parts, it is required to improve both thinness and rigidity. When making the housing only of resin, it is necessary to increase the wall thickness to improve rigidity. However, by laminating metal, it is possible to improve the rigidity of the entire laminate without increasing the wall thickness of the resin part. For example, in the case of a housing made of PC or the like, since the upper limit of the housing thickness is often determined, the ability to improve the overall rigidity without increasing the wall thickness of the resin is an advantage. One way to improve this rigidity is to increase the flexural modulus of the material. Therefore, the inventors repeatedly conducted research to improve the flexural modulus to some extent in the molded body by secondary processing and also in the flat plate state before molding. Although the reason why the flexural modulus of the molded body is lower than that of the flat plate is not yet clear, it is presumed that the material flow of the carbon fiber reinforced resin during secondary processing affects the flexural modulus.

[0016] And by using a laminated composite in which a carbon fiber reinforced resin and a steel plate are laminated, it has been found that the flexural modulus can be improved in the flat plate state compared to the case of only the carbon fiber reinforced resin. Furthermore, when a molded body is manufactured by secondary processing, although a decrease in the flexural modulus compared to the flat plate is inevitable, it has been found that the flexural modulus can be improved compared to the case of only the carbon fiber reinforced resin, leading to the present invention.

[0017] That is, in the laminated composite 10 in the present embodiment, by setting the flexural modulus of the flat plate to 30 GPa or more, the flexural modulus of the molded body can be set to a predetermined value or more even when manufacturing automotive members or the like by secondary processing. Here, the value of the flexural modulus of the present embodiment can be obtained in accordance with ASTM D - 790.

[0018] In addition, in the laminated composite 10 of the present embodiment, the specific flexural modulus is preferably 20 or more from the same viewpoint as above. The specific flexural modulus is a value obtained by dividing the flexural modulus obtained as described above by the specific gravity of the laminated composite 10. The thickness of the laminated composite 10 of the present embodiment is not particularly limited and can be appropriately changed depending on the application. For example, it is preferably about 0.3 mm to 3.0 mm from the viewpoints of physical properties and moldability.

[0019] <Carbon fiber reinforced resin 110> Next, the carbon fiber reinforced resin 110 used in the laminated composite 10 of the present embodiment will be described. As the carbon fiber reinforced resin 110, a carbon fiber reinforced resin in which chopped strand prepregs in which carbon fibers are impregnated in a resin are oriented so as to exhibit pseudo-isotropy is applied.

[0020] Specifically, the carbon fiber used may be a pitch-based carbon fiber or a PAN-based carbon fiber, but from the viewpoint of handleability, it is preferably a PAN-based carbon fiber. The filament diameter of one carbon fiber is usually 5 to 8 μm, and a fiber bundle in which a plurality of carbon fibers are assembled flatly with a predetermined number of filaments is preferably used. The number of filaments of the carbon fiber is 3000 to 600000, more preferably 6000 to 24000, from the viewpoint of the productivity of prepreg production. Further, when used in the laminated composite 10, the carbon fiber may be used alone or in combination with reinforcing fibers other than the carbon fiber. Examples of the reinforcing fibers that can be combined include known fibers such as aramid fibers, polyethylene fibers, glass fibers, metal fibers, and natural fibers.

[0021] The carbon fiber used in the laminated composite 10 of the present embodiment is preferably fibrillated from the viewpoint of facilitating the penetration of the matrix resin during prepreg production. When using a combination of reinforcing fibers other than carbon fiber, it is preferable that the reinforcing fibers other than the carbon fiber are also fibrillated.

[0022] On the one hand, from the perspective of processability and the like as described above, it is preferable that the resin used for the carbon fiber reinforced resin 110 is a thermoplastic resin. As the thermoplastic resin, known thermoplastic resins used as the matrix of the fiber reinforced resin can be applied. Specifically, it is preferable to use a thermoplastic epoxy resin which is a site polymerization type, and it is particularly preferable to use a bisphenol A type epoxy resin from the viewpoints of high permeability to fibers during prepreg production and adhesiveness to the steel plate used in the present embodiment.

[0023] The carbon fiber reinforced resin 110 used in the present embodiment can be obtained as follows. That is, a unidirectional prepreg (for example, a UD (Uni-Directional) tape) obtained by impregnating the above-described carbon fiber into a thermoplastic resin and cut into a predetermined length (chopped strand prepreg) is randomly scattered and laminated, and then heated to soften the resin and fix the tape pieces to each other, whereby the carbon fiber reinforced resin 110 of the present embodiment can be obtained. In addition, the carbon fiber reinforced resin 110 can also be obtained by a method of randomly laminating tape pieces and then heating and pressing, or a method of directly scattering and laminating in a mold during the production of the laminated composite 10.

[0024] Further, as the unidirectional prepreg used for the carbon fiber reinforced resin 110 of the present embodiment, it is preferable to use one in which the thermoplastic resin is uniformly impregnated without voids (such as air bubbles) between the fibers during prepreg production. Thereby, the adhesiveness of the unidirectional prepreg in the obtained carbon fiber reinforced resin 110 is increased, and it becomes possible to enhance the strength and isotropy in the physical properties of the laminated composite 10.

[0025] In the laminated composite 10 of the present embodiment, it is preferable that the fiber volume content Vf in the unidirectional prepreg is controlled to be preferably 30 to 55%, more preferably 35 to 45%. Setting it within the above range is preferable from the viewpoint of enhancing the moldability of the molded body to be manufactured. When the volume content exceeds the above upper limit value, the non-impregnated portion of the prepreg increases and it becomes difficult to achieve a void-free state, which is not preferable. Also, when it is less than the lower limit value, it becomes difficult to ensure the strength of the laminated composite 10, which is not preferable. Also, the average length of the unidirectional prepreg in the fiber direction is 10 to 50 mm, preferably 10 to 30 mm.

[0026] Note that by randomly laminating the chopped strand prepreg as described above, the carbon fiber reinforced resin 110 comes to exhibit pseudo-isotropy, and as a result, the moldability of the obtained laminated composite 10 can be improved. Further, in the present embodiment, as the above-described tape-shaped unidirectional prepreg, for example, those disclosed in Patent Document 1 can be used. The thickness of the carbon fiber reinforced resin 110 in the present embodiment is not particularly limited, but for example, being about 0.1 mm to 2.0 mm is preferable from the viewpoint of weight reduction. Also, the thickness of the carbon fiber reinforced resin may be appropriately changed according to the shape of the obtained molded body. The flexural modulus Gc of the carbon fiber reinforced resin 110 in the present embodiment is preferably 20 GPa or more from the viewpoint of the flexural modulus required for the laminated composite 10.

[0027] <Steel plate 120> Next, the steel plate 120 will be described. As shown in FIG. 1, the steel plate 120 of the present embodiment may be laminated on at least one side of the above-described carbon fiber reinforced resin 110, or may be in a form laminated on both sides of the carbon fiber reinforced resin 110 (not shown), or a form in which both are alternately laminated in multiple layers.

[0028] Examples of the steel sheet 120 used in the laminated composite 10 of the present embodiment include known steel sheets. As the steel sheet, a hot-rolled steel sheet obtained by hot-rolling an aluminum-killed continuous cast steel and removing the scale generated on the surface, or a cold-rolled steel sheet obtained by cold-rolling a hot-rolled steel sheet and annealing it can be applied.

[0029] Note that, as the steel sheet 120 used in the present embodiment, a surface-treated steel sheet is more preferable from the viewpoints of adhesion to the carbon fiber reinforced resin 110 (suppression of gaps at the laminated interface), control of the friction coefficient, particularly improvement of formability by reducing the friction coefficient, corrosion resistance, and the like. Examples of the surface treatment include plating, chemical conversion treatment, resin coating, or surface roughening, and any of them can be preferably used.

[0030] Among these, as the plated steel sheet, for example, a single-layer plating made of any one of Sn, Ni, Co, Mo, Zn, and Cr, or a plated steel sheet subjected to a multi-layer plating or alloy plating (composite plating) composed of two or more kinds can be used. Among these, in particular, a Zn-plated steel sheet or a Ni-plated steel sheet is preferable. At this time, the Zn plating includes Zn alloy plating, and the Ni plating includes Ni alloy plating. In addition, as the above-described chemical conversion treatment, for example, known chemical conversion treatments such as chromate-based, phosphate-based, vanadate-based, and silicate-based chemical conversion treatments can be applied. In addition, examples of the above-described resin coating include known polyester resins, urethane resins, acrylic resins, and the like. In addition, as the above-described surface roughening, for example, in addition to quality rolling using a rolling roll with a predetermined surface roughness, the surface of the steel sheet can be roughened using known roughening techniques such as blast treatment, chemical etching, or laser irradiation, and the adhesion between the steel sheet 120 and the carbon fiber reinforced resin 110 can be improved by the anchor effect. In order to achieve both formability and adhesion, it is preferable to roughen the interface side of the steel sheet 120 with the carbon fiber reinforced resin 110. On the other hand, the other surface (opposite side) that becomes the outer surface may be smooth without being roughened from the viewpoints of reducing the friction coefficient and design.

[0031] The steel sheet 120 of the present embodiment is characterized in that its tensile fracture elongation (φ) is 20% or more. That is, as described above, the laminated composite 10 of the present embodiment is characterized by sharing the flexural modulus and formability in the flat plate state at a high level. As a result of the inventors' repeated experiments, while the tensile fracture elongation of the steel sheet 120 is 20% or more, the flexural modulus of the laminated composite 10 in the flat plate state is 30 GPa or more, so that the flexural modulus and formability are shared at a high level.

[0032] The thickness (plate thickness t) of the steel sheet 120 of the present embodiment preferably ranges from about 0.05 to 2.0 mm, and particularly preferably ranges from 0.05 to 0.50 mm, although it depends on the use of the obtained laminated composite 10. When the thickness of the steel sheet 120 is less than 0.05 mm, it is not preferable in terms of manufacturing and handling. On the other hand, when it exceeds 2.0 mm, it becomes difficult to achieve the purpose of weight reduction or the like in the final molded product. In the present embodiment, the thickness ratio of the steel sheet 120 to the total thickness of the laminated composite 10 is preferably 1 to 50%, and more preferably 1 to 20% from the viewpoint of highly achieving weight reduction, strength, flexural modulus, etc.

[0033] Furthermore, when the friction coefficient on the surface (the surface in contact with the mold) of the steel sheet 120 of the present embodiment is μ, the parameter S represented by the following calculation formula (1) is preferably 7.5 or more. S = (plate thickness t of the steel sheet × tensile fracture elongation φ) / (friction coefficient μ of the steel sheet) ··· (1) As described above, it is necessary to reinforce the flexural modulus of the carbon fiber reinforced resin 110 with the steel sheet 120. When the parameter S is 7.5 or more, preferable formability of the laminated composite 10 can be obtained. When the parameter S is 20 or more, more preferable results can be obtained from the viewpoint of formability.

[0034] The friction coefficient μ of the steel plate in the above formula (1) can be measured by a known friction coefficient measuring device. For example, specifically, it can be measured by a tribogear surface property measuring machine (TYPE: 14FW) manufactured by Shinato Scientific Co., Ltd. As an example of the measurement conditions, it can be carried out under the following conditions. Load: 200 g Measurement distance: 20 mm, Moving speed: 100 mm / min, Test environment: 200 °C, Counter material: SUS304 (φ10 mm) Note that the friction coefficient μ can vary depending on the finish surface roughness and surface treatment of the steel plate. For example, by reducing the friction coefficient of the steel plate in contact with the mold surface during the production of the molded body, the steel plate can easily flow into the mold, and it is difficult for cracks and wrinkles to occur on the steel plate after molding.

[0035] Next, an example of the manufacturing method of the laminated composite 10 (flat plate shape) in the present embodiment is shown below. First, heat the mold for the flat laminated composite to 180 °C at a rate of 5 °C / min. After the mold temperature reaches 180 °C, the carbon fiber reinforced resin 110 and the steel plate 120 are put into the mold and held at, for example, 180 °C and 0.5 MPa for 3 minutes. Next, press at, for example, 180 °C and 4 MPa for 12 minutes and then cool naturally. Then, when the mold temperature drops to 70 °C or lower, unload (release the press) to obtain the laminated composite 10 of the present embodiment. Note that the manufacturing method of the flat laminated composite 10 is not limited to the above manufacturing conditions. As long as the characteristics of the laminated composite 10 are possessed, known manufacturing methods can be applied. For example, a method of extruding the molten carbon fiber reinforced resin 110 onto the steel plate 120, or a method of laminating a heat adhesive film on the steel plate 120 and then thermocompression bonding the steel plate 120 with the heat adhesive film and the carbon fiber reinforced resin 110 to form the laminated composite 10 are also applicable.

[0036] ≪Molded body 20≫ Next, the molded body 20 in the present embodiment will be described. The molded body 20 in the present embodiment is characterized by being molded by the above-described laminated composite 10. That is, when manufacturing a molded body by subjecting the above-described laminated composite 10 to press molding or the like under heating and / or pressure by, for example, a press molding method, even when using a mold with a relatively small R at the corners, it is possible to suppress the occurrence of at least one of wrinkles, breaks, and gaps at the lamination interface in the molded body.

[0037] FIG. 2 shows an example of a mold MD as a mold for manufacturing the molded body 20 of the present embodiment. FIG. 2(a) is a front view of the mold MD used for manufacturing the molded body 20 of the present embodiment, and FIG. 2(b) is a side view thereof. As shown in FIGS. 2 and 3, the mold MD has shoulders with a plurality of punch shoulder radii R. That is, FIG. 3(a) is an enlarged view of shoulder A in FIG. 2(b), FIG. 3(b) is an enlarged view of shoulder B in FIG. 2(a), and FIG. 3(c) is an enlarged view of shoulder C in FIG. 2(a) seen from the side. As shown in FIG. 3, shoulder A in the mold MD is R2, shoulder B is R10, and shoulder B has R2 and R7 continuous. Therefore, the mold MD includes shoulders with a plurality of shoulder radii.

[0038] Thus, since it is molded from the above-described laminated composite 10 using the above-described mold MD, the molded body 20 in the present embodiment is characterized by having shoulders with a punch shoulder radius of 0 < R ≤ 2. Further, it is preferable that this molded body is manufactured by one-time press molding. Also, the molded body 20 of the present embodiment preferably has a plurality of punch shoulder radii as shown in FIGS. 2 and 3.

[0039] Here, the laminated composite 10 of the present embodiment has the characteristics that the tensile fracture elongation φ of the steel plate 120 is 20% or more and the flexural modulus of elasticity in a flat plate is 30 GPa or more. Also, even if the laminated composite 10 of the present embodiment is molded using a mold having shoulders with a small shoulder radius R like the mold MD shown in FIGS. 2 and 3, it is possible to suppress either the gap between the carbon fiber reinforced resin 110 and the steel plate 120, or wrinkles and breaks in the steel plate 120, and improve the rigidity as a laminated composite without increasing the thickness of the resin part. Note that the mold suitable for this embodiment is not limited to those shown in FIGS. 2 to 3, and it goes without saying that any mold having a shoulder with a shoulder radius of 0 < R ≤ 2 can be applied to the production of the molded body 20 of this embodiment.

[0040] <<Method for manufacturing a molded body>> As the method for manufacturing the molded body 20 described above, a method of press-molding the above-described laminated composite 10 using a molding die having a shoulder with a shoulder radius of 0 < R ≤ 2 can be applied. Alternatively, a method of press-molding the above-described carbon fiber reinforced resin 110 and steel plate 120 using a molding die having a shoulder with a shoulder radius of 0 < R ≤ 2 can be applied.

[0041] An example of the method for manufacturing the molded body 20 in this embodiment is shown below. First, the mold for the molded body 20 is heated to 200°C at a rate of 10°C / min. After the mold temperature reaches 200°C, the carbon fiber reinforced resin 110 and the steel plate 120 are introduced into the mold and held at 200°C and 0.5 MPa for 1 minute. Next, it is pressed at 200°C and 10 MPa for 5 minutes and then cooled naturally. When the mold temperature drops to 70°C or lower, the load is removed, and the molded body 20 can be obtained. Note that the method for manufacturing the molded body 20 is not limited to the above manufacturing conditions, and any known manufacturing method can be applied as long as it has the characteristics of the molded body 20 described above.

[0042] Also, in the above example, an example of manufacturing the molded body 20 without passing through the laminated composite 10 was shown and described, but this embodiment is not limited to this. That is, the laminated composite 10 and the molded body 20 may be manufactured separately. In this case, first, each of the carbon fiber reinforced resin 110 and the steel plate 120 is introduced into the same mold to manufacture the laminated composite 10, and then the molded body 20 can be formed as a secondary process.

Example

[0043] Hereinafter, the present invention will be described more specifically with reference to examples.

[0044] <Example 1> [Preparation of Carbon Fiber Reinforced Resin] First, carbon fiber yarns (PYROFIL TR50S15L: manufactured by Mitsubishi Chemical Corporation) were opened to a predetermined width (15 - 17 mm), and an opened tape was prepared using a known fiber opening device. Next, a thermoplastic epoxy resin (XNR / H6850V: manufactured by Nagase ChemteX Corporation) in a heat - melted state was prepared and uniformly mixed using a stirrer to obtain a resin composition having a viscosity of 100 - 200 mPa·s. After impregnating the obtained opened tape with the above resin composition, it was heated and cured to obtain a tape - shaped unidirectional prepreg (fiber volume content (Vf): 40% ± 2%). The obtained tape - shaped unidirectional prepreg was cut to a length of 13 mm to obtain a chopped strand prepreg. The chopped strand prepreg was scattered and laminated in a mold so that the fiber directions were random (quasi - isotropic), and then heated at 150°C for 1 minute and 30 seconds to soften the resin contained in the chopped strand prepreg and fix the tape pieces to each other, thereby obtaining a carbon fiber reinforced resin (thickness: equivalent to 1.9 mm).

[0045] [Preparation of Steel Plate] A cold - rolled steel plate with a thickness of 0.1 mm was subjected to alkaline electrolytic degreasing treatment and sulfuric acid pickling treatment using a conventional method. The tensile elastic modulus, tensile fracture elongation (elongation) (%), specific gravity, friction coefficient, and parameter S obtained from the above - mentioned calculation formula were as shown in Table 1.

[0046] [Manufacture of Laminated Composite] After heating the mold for the above - mentioned flat - plate - shaped laminated composite to 180°C, the above - mentioned carbon fiber reinforced resin and steel plate were put into the mold, pre - heated at 180°C and 0.5 MPa for 3 minutes, and then pressed at 180°C and 4 MPa for 12 minutes. After cooling to 70°C, unloading and taking out were performed to obtain a laminated composite.

[0047] [Manufacture of Molded Body] As a mold for the molded body, the mold MD shown in Figure 2 was prepared. This mold MD had a plurality of corner parts, and the R values of each corner part were R2, R7, and R10. The laminated composite obtained above was put into a mold MD heated to 200°C. At this time, the convex outer surface of the molded body was made into a steel plate. After the input, preheating was carried out at 200°C and 0.5 MPa for 1 minute, then pressed at 200°C and 10 MPa for 5 minutes, cooled to 70°C, and then demolded to obtain a molded body.

[0048] [Evaluation] (A) Evaluation of flexural properties (flexural modulus) The flexural modulus of the flat laminated composite was evaluated as follows. The average flexural modulus of the laminated composite was measured in accordance with ASTM D-790 using a precision universal testing machine (Autograph AG-100kNXplus) manufactured by Shimadzu Corporation. Specifically, from the obtained flat laminated composite (flat plate), rectangular samples with a length of 80 ± 1.0 mm and a width of 25 ± 0.2 mm were cut out in an arbitrary length direction and used as measurement samples. In the same way, a total of 10 measurement samples were prepared. For each measurement sample, the flexural modulus was measured at a support span of 64 mm and a test speed of 3.4 mm / min, divided into 5 samples with the indenter side as the steel surface and 5 samples with the carbon surface. The average value of the flexural moduli obtained for the 10 measurement samples was shown in Table 2 as the average flexural modulus. The specific flexural modulus was also shown in Table 2. In addition, when the average flexural modulus was 30 or more, it could be judged as good.

[0049] (B) Evaluation of formability The formability evaluation of the molded body manufactured from the laminated composite obtained above was carried out as follows. That is, regarding the drawn surfaces at the corners and the central part of the obtained molded body, (a) whether there is a break in the steel plate, (b) whether wrinkles are generated on the surface of the steel plate, and (c) whether a gap is generated at the laminated surface between the carbon fiber reinforced resin and the steel plate were visually observed. As a result of the observation, evaluation was carried out with ◎, ○, and × as follows and shown in Table 2. ◎: Neither wrinkles nor breaks are present at both the corners and the central part, and no gap is generated at the laminated surface. ○: Wrinkles, breaks, and gaps are generated at the corners. ×: Wrinkles, breaks, and gaps are generated at both the corners and the central part.

[0050] <Example 2> The thicknesses of the carbon fiber reinforced resin and the steel plate were made as shown in Table 1. The annealing conditions of the steel plate were changed to make the elongation as shown in Table 1. The friction coefficient is also shown in Table 1. Otherwise, the procedure was the same as in Example 1. The results are shown in Table 2.

[0051] <Example 3> The thicknesses of the carbon fiber reinforced resin and the steel plate were made as shown in Table 1. The annealing conditions of the steel plate were changed to make the elongation as shown in Table 1. The friction coefficient is also shown in Table 1. Otherwise, the procedure was the same as in Example 1. The results are shown in Table 2.

[0052] <Example 4> The annealing conditions of the steel plate were changed to make the elongation as shown in Table 1. The friction coefficient is also shown in Table 1. As the steel plate, a surface-treated steel plate subjected to composite Zn plating composed of Zn-Co-Mo and phosphating treatment was used. Otherwise, the procedure was the same as in Example 2. The results are shown in Table 2.

[0053] <Example 5> The annealing conditions of the steel plate were changed to make the elongation as shown in Table 1. The friction coefficient is also shown in Table 1. As the steel plate, a surface-treated steel plate subjected to composite Zn plating composed of Zn-Co-Mo, vanadium-based chemical conversion treatment, and urethane resin coating was used. Otherwise, the procedure was the same as in Example 2. The results are shown in Table 2.

[0054] <Example 6> The annealing conditions of the steel plate were changed to make the elongation as shown in Table 1. The friction coefficient is also shown in Table 1. As the steel plate, a surface-treated steel plate subjected to composite Zn plating composed of Zn-Co-Mo, vanadium-based chemical conversion treatment, and olefin-modified acrylic resin coating was used. Otherwise, the procedure was the same as in Example 2. The results are shown in Table 2.

[0055] <Example 7> In the production of the laminated composite, first, a heat-adhesive film was thermally laminated onto a steel plate to produce a steel plate with a heat-adhesive film. Next, this steel plate with a heat-adhesive film and a carbon fiber reinforced resin were thermocompression bonded to obtain a laminated composite. Then, the obtained laminated composite was pressed at 180 °C and 4 MPa for 12 minutes. After cooling to 70 °C, unloading and taking out were performed to obtain a laminated composite. Otherwise, it was carried out in the same manner as in Example 2. The results are shown in Table 2.

[0056] <Example 8> The annealing conditions of the steel plate were changed so that the elongation was as shown in Table 1. The friction coefficient is also shown in Table 1. Otherwise, it was carried out in the same manner as in Example 2. The results are shown in Table 2.

[0057] <Comparative Example 1> It was carried out in the same manner as in Example 1 except that the thickness of the carbon fiber reinforced resin was 2.0 mm and no steel plate was used. The results are shown in Table 2.

[0058] <Comparative Example 2> The carbon fiber reinforced resin was a carbon fiber fabric impregnated with a thermoplastic polypropylene resin. The thickness and fiber volume content (Vf) were as shown in Table 1. Otherwise, it was carried out in the same manner as in Example 2. The results are shown in Table 2.

[0059] <Comparative Example 3> The annealing conditions of the steel plate were changed so that the elongation was as shown in Table 1. The friction coefficient is also shown in Table 1. Otherwise, it was carried out in the same manner as in Example 2. The results are shown in Table 2.

[0060] <Comparative Example 4> The annealing conditions of the steel plate were changed so that the elongation was as shown in Table 1. The friction coefficient is also shown in Table 1. Otherwise, it was carried out in the same manner as in Example 2. The results are shown in Table 2.

[0061] <Comparative Example 5> An aluminum plate with a thickness of 0.1 mm was used as the steel plate. The elongation rate, etc. were as shown in Table 1. Otherwise, it was carried out in the same manner as in Example 1. The results are shown in Table 2.

[0062] <Comparative Example 6> The annealing conditions of the steel sheet were changed so that the elongation was as shown in Table 1. The friction coefficient is also shown in Table 1. Otherwise, it was carried out in the same manner as in Example 2. The results are shown in Table 2.

[0063]

Table 1

[0064]

Table 2

[0065] It was confirmed that each example had characteristics such as a preferable bending elastic modulus and formability. On the other hand, it was confirmed that none of the comparative examples had such characteristics.

[0066] In addition, various modifications are possible for the above-described embodiments and each example without departing from the gist of the present invention. Further, although the laminated composite and the molded body using the same in the above-described embodiments have been described as being mainly used for automotive members, housings of electronic devices, etc., they are not limited to those applications, and for example, they can also be applied to other applications such as heat dissipation materials and electromagnetic wave shielding materials.

Industrial Applicability

[0067] As described above, the laminated composite of the present invention and the molded body using the same can be applied to industries in a wide range of fields such as automobiles and electronic devices.

Explanation of Signs

[0068] 10 Laminated composite 110 Carbon fiber reinforced resin 120 Steel sheet 20 Molded body MD Mold

Claims

1. A carbon fiber reinforced resin in which chopped strand prepregs impregnated with carbon fibers in a thermoplastic resin are oriented to exhibit pseudo-isotropy, and a steel plate laminated on at least one surface of the carbon fiber reinforced resin and having a tensile fracture elongation φ of 20% or more, the laminated composite comprising: The flexural modulus of elasticity of a flat plate obtained in accordance with ASTM D-790 is 30 GPa or more, The laminated composite is characterized in that the specific flexural modulus of elasticity of the laminated composite obtained by dividing the flexural modulus of elasticity by the specific gravity of the laminated composite is 20 GPa or more.

2. The laminated composite according to claim 1, wherein the thickness ratio of the steel plate to the total thickness of the laminated composite is 1% to 20%.

3. The laminated composite according to claim 1 or 2, wherein the steel plate has a value S of the following formula of 7.5 or more. However, S [mm] = (plate thickness t [mm] of the steel plate × tensile fracture elongation φ) / (friction coefficient μ of the steel plate), and φ is in % notation.

4. The laminated composite according to any one of claims 1 to 3, wherein the steel plate is a surface-treated steel plate and the surface treatment is plating containing Zn or Ni.

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