Integral molding of fiber-reinforced resin layer and shielding layer and method for manufacturing the same

Abstract

Provided is an integrally molded body that has a blocking layer for cutting off radio waves and magnetic waves. This integrally molded body comprises a fiber-reinforced resin layer containing reinforcing fibers and a first matrix resin, and a blocking layer, wherein the blocking layer contains an aggregate of metal strips and a second matrix resin, and blocks at least one of an electric field or a magnetic field, the metal strips being dispersed in the surface of the blocking layer to form the aggregate.

Description

[Technical Field]

[0001] The present invention relates to an integrally molded body of a fiber-reinforced resin layer and a shielding layer, and a method for manufacturing the same. [Background technology]

[0002] Many studies have been conducted on techniques for shielding electric fields using metal and resin. Patent Document 1 describes a resin molded article containing foil-like metal flakes in which flakes of a laminate of metal foil and plastic film are randomly dispersed and adhered to each other.

[0003] Patent Document 2 describes a method for forming an electromagnetic shielding resin outer panel, in which an uneven surface is formed in a mold that forms the back surface of the outer panel, aluminum foil and SMC (sheet molding compound) are placed one on top of the other in the mold, and the aluminum foil is bonded to the resin by heating and pressure molding.

[0004] Patent Document 3 provides a vehicle structure that has an electromagnetic wave shielding effect while simplifying the manufacturing process by providing a portion where the electromagnetic wave shielding layer does not follow the components of a battery box having a recess.

[0005] Patent Document 4 describes an electromagnetic shielding material that is formed by integrally molding at least two elastic layers made of resin elastic fibers with a shielding layer of granular or flake-like magnetic material sandwiched between them, thereby partially melting and solidifying the elastic fibers and entangling the magnetic material with the elastic fibers to hold it in a semi-floating state. In the electromagnetic shielding material described in Patent Document 4, the particles or flakes can move freely to a certain extent, and even if the shielding material is deformed by an external load or impact, the particles or flakes do not distort, and the shielding properties do not deteriorate. The electromagnetic wave shielding material described in Patent Document 5 can be formed into a highly processed electromagnetic wave shielding material, such as a box-shaped material, by heat molding, and the conductive composition layer is not destroyed during processing, so that stable electromagnetic wave shielding performance is maintained. The invention described in Patent Document 6 discloses an electromagnetic wave shielding composite material in which a fiber-reinforced resin molded body portion containing carbon fibers and a matrix resin and a metal layer portion are laminated together. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 58-84856 [Patent Document 2] Japanese Patent Publication No. 4-110278 [Patent Document 3] International Publication No. 2021 / 125386 [Patent Document 4] Japanese Patent Publication No. 09-292480 [Patent Document 5] Japanese Patent Publication No. 06-021683 [Patent Document 6] Japanese Patent Application Publication No. 2012-109454 Summary of the Invention [Problem to be solved by the invention]

[0007] Vehicle structures are sometimes required to have shielding properties to block radio waves and magnetic waves. However, the resin molded article containing foil-like metal flakes described in Patent Document 1 is made by simply mixing metal flakes into a resin molded article, which may result in poor shielding against radio waves or magnetic fields. Generally, the higher the conductivity of a material, the better the shielding against electric fields or magnetic fields. In the resin molded article containing foil-like metal flakes described in Patent Document 1, the metal flakes are covered with resin, so the metal flakes are not in contact with each other. For this reason, the conductivity of the resin molded article described in Patent Document 1 is not high, and the shielding against electric fields or magnetic fields is insufficient.

[0008] Although Patent Document 2 attempts to shape aluminum foil by creating irregularities, it only discloses a method for forming simple shapes such as flat plates. With the forming method described in Patent Document 2, even if an attempt is made to create an integrally formed body having a top surface and a vertical surface, such as a hat shape, it is not possible to shape the aluminum foil by following the resin.

[0009] In Patent Document 3, the electromagnetic wave shielding layer is not made to conform to the components of the battery box, even if they have recesses. No technology has been considered for making the shielding layer conform to recesses or deep-drawn portions. To install the shielding layer so that it conforms to a molded body with a complex shape, the shielding layer must be pre-formed and then bonded to the molded body, which increases the number of assembly steps. Furthermore, if an attempt is made to simultaneously mold the shielding layer precursor (flat plate) and molding material without prior shaping (pre-forming) in order to prevent the increase in steps, there is a problem of the shielding layer becoming misaligned.

[0010] In the electromagnetic wave shielding material described in Patent Document 4, the flake magnetic material used in the shielding layer is too heavy. Also, only one of the two types of resin is melted, leaving it in a semi-floating state, so it is not fixed in place. The electromagnetic wave shield described in Patent Document 5 uses metal fibers, which causes gaps. The electromagnetic wave shielding composite material described in Patent Document 6 uses a metal plate, and therefore the metal plate cannot conform when integrally molded into a molded article having a complex shape. [Means for solving the problem]

[0011] As a result of extensive investigations, the present inventors have found that the above problems can be solved by the following means, and have arrived at the present invention.

[0012] 1. An integrally molded body of a fiber-reinforced resin layer containing reinforcing fibers and a first matrix resin and a shielding layer, the shielding layer is a layer including an assembly of metal strips and a second matrix resin, and shields at least one of an electric field and a magnetic field; the assembly of metal strips comprises a plurality of metal strips distributed within the surface of the shielding layer; One-piece molding. 2. The integrally molded body according to 1 above, which has a top surface portion and a vertical surface portion. 3. An integrally molded body according to any one of items 1 or 2, having a portion that satisfies 2≦tx / ty, where tx is the thickness of the shielding layer and ty is the thickness of the metal strip. 4. The integrally molded body according to any one of items 1 to 3, wherein the mass ratio W(metal) of the aggregate of the metal strips in the shielding layer is 30% or more. 5. An integrally molded body according to any one of items 1 to 4, wherein the metal strip has a width of 1 mm to 40 mm, a length of 1 mm to 100 mm, and a thickness of 100 μm or less. 6. The integrally molded body according to any one of items 1 to 5, wherein the reinforcing fibers are discontinuous fibers and are dispersed in the in-plane direction of the fiber-reinforced resin layer. 7. An integrally molded body described in any one of items 1 to 6, wherein the shielding layer has an electric or magnetic field shielding property of 10 decibels or more in at least a portion of the range from more than 0 MHz to 3000 MHz. 8. An integrally molded body described in any one of items 1 to 6, wherein the shielding layer has an electric or magnetic field shielding property of 10 decibels or more in at least a portion of the range exceeding 0 MHz and up to 100 MHz. 9. The integrally molded body according to item 2, wherein the thickness ta of the vertical surface portion and the thickness tb of the top surface portion satisfy the relationship ta≦tb. 10. When the thickness of the shielding layer in the vertical surface portion is txa, the thickness of the fiber reinforced resin layer is ta-txa, the thickness of the shielding layer in the top surface portion is txb, and the thickness of the fiber reinforced resin layer is tb-txb, txa≦txb and ta-txa≧tb-txb are satisfied. 10. The integrally molded body according to item 9 above. 11. A vehicle structure having the integrally molded article according to any one of items 1 to 10. 12. A component of a battery box having the integrally molded body according to any one of items 1 to 10, Components of the battery box arranged at the lower part of the vehicle body. 13. A method for manufacturing the integrally formed body according to any one of items 1 to 10, comprising laminating a fiber reinforced resin containing a reinforcing fiber and a first matrix resin and a shielding layer precursor, and performing press molding using an upper molding die and a lower molding die. 14. A method for manufacturing the integrally formed body according to item 13, comprising laminating the fiber reinforced resin and the shielding layer precursor so that the fiber reinforced resin contacts the lower molding die, arranging the laminated body on the lower molding die, and performing press molding. A method for manufacturing the integrally formed body according to item 13. 15. A method for manufacturing the integrally formed body according to any one of items 13 or 14, wherein the relationship between the extensibility E1 of the fiber reinforced resin and the extensibility E2 of the laminate of the fiber reinforced resin and the shielding layer precursor is 0.9 < E1 / E2 < 50. 16. A method for manufacturing the integrally formed body according to any one of items 13 to 15, wherein the first matrix resin and the second matrix resin are thermoplastic resins.

Advantages of the Invention

[0013] By using an aggregate of metal strips, it is possible to integrally mold with a fiber reinforced resin layer having a complex three-dimensional shape, and the process of preforming a metal shielding layer and bonding it to the fiber reinforced resin layer can be simplified.

Brief Description of the Drawings

[0014] [Figure 1] A schematic cross-sectional view of the integrally formed body. [Figure 2A] A state where only a metal plate is shaped using a molding die. Before the upper die closes. [Figure 2B] A state where the upper die closes and presses the metal plate. [Figure 3] A plan view showing an example of the shielding layer precursor 20. [Figure 4] A photograph showing a state where some of the metal strips are lying down. [Figure 5A] Evaluation of the electromagnetic shielding performance of a polypropylene resin layer with a thickness of 150 μm. [Figure 5B]This is an evaluation of the electric field shielding performance of a 150 μm thick shielding layer containing an aluminum thin film and polypropylene resin when the mass fraction W of the aluminum thin film is 25%. [Figure 5C] This is an evaluation of the electric field shielding performance of a 150 μm thick shielding layer containing an aluminum thin film and polypropylene resin when the mass fraction W of the aluminum thin film is 45%. [Figure 5D] This is an evaluation of the electric field shielding performance of a 150 μm thick shielding layer containing an aluminum thin film and polypropylene resin when the mass ratio W of the aluminum thin film is 65%. [Figure 5E] This is an evaluation of the electric field shielding performance of a 150 μm thick shielding layer containing an aluminum thin film and polypropylene resin when the mass ratio W of the metal (aluminum) thin film is 75%. [Figure 5F] This is an evaluation of the electric field shielding performance of a 150 μm thick aluminum thin film. [Figure 6] Schematic diagram of slitting a metal strip by pressing it against a support roller. [Figure 7] Schematic side view of slitting a metal strip using a shear blade method. [Figure 8] FIG. 8 is a cross-sectional view taken along the line VIII-VIII in FIG. 7. [Figure 9] FIG. 9 is an enlarged view of part IX in FIG. 8. [Figure 10] Schematic diagram of slitting metal strip using the gang method. [Figure 11] FIG. 11 is a cross-sectional view taken along the line XI-XI in FIG. [Figure 12] FIG. 12 is an enlarged view of part XII in FIG. [Figure 13] FIG. 1 is a cross-sectional view showing an example of an integrally molded body 1A. [Figure 14] FIG. 10 is an exploded perspective view showing an example of a battery box using an integrally molded body. [Figure 15] FIG. 2 is a perspective view showing an example of a battery tray. [Figure 16] 16 is a cross-sectional view taken along the line XVI-XVI in FIG. 15. [Figure 17A] FIG. 2 is a schematic diagram for explaining a method for measuring a molding heating temperature. [Figure 17B] FIG. 1 is a schematic diagram for explaining a method for measuring ductility. [Figure 17C] FIG. 1 is a schematic diagram for explaining a method for measuring ductility. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to these.

[0016] 1 is a schematic cross-sectional view showing a laminate 1 for forming an integrally molded body according to an embodiment of the present invention. The laminate 1 has a fiber-reinforced resin 10 and a shielding layer precursor 20.

[0017] [Shielding layer precursor] 1, the shielding layer precursor 20 is a layer including an assembly of metal strips 30 and a second matrix resin 40. The assembly of metal strips 30 shields at least one of an electric field and a magnetic field. The metal strips 30 are dispersed within the shielding layer precursor 20 to form aggregates.

[0018] [Advantages of using an aggregate of metal strips during molding] 1. Issues with conventional technology When a metal sheet is formed separately from a fiber-reinforced resin layer without using an assembly of metal strips, the unevenness of the forming mold tends to cause tearing, especially at the corners. This is because the metal sheet (e.g., aluminum foil) stretches at the corners beyond its breaking elongation. The location where the metal sheet 1102 is prone to tearing is shown as 1101 in Figure 2B. When forming using only the metal sheet, it is necessary to provide a gentle curve at the corners of the forming mold to prevent the metal sheet from being torn by the forming mold. Another method, which has been used to improve yield, is to reinforce the location shown as 1101 in Figure 2B with cushioning or reinforcing material such as gum tape to prevent tearing. Furthermore, when deep drawing is performed on a metal plate, not only at the corners shown in Figure 2B, but also at the corners, wrinkles tend to form at those locations. Alternatively, it was necessary to devise a design for the metal layer that would soften the sharpness of the corners.

[0019] 2. Effect of metal strip assembly (i) On the other hand, when integrally molded using an assembly of metal strips, the shielding layer precursor is less likely to break even when it hits the corners of the mold, and there is no need to provide soft curves to the corners of the mold.

[0020] 3. Effect of metal strip aggregation (ii) When the resin contained in the fiber-reinforced resin is a thermoplastic resin and cold press molding is used, if the shielding layer precursor is placed in the lower mold and the fiber-reinforced resin is layered so that it comes into contact with the upper mold, the fiber-reinforced resin will not cool to the mold temperature until just before it comes into contact with the upper mold. This makes it easier to add ribs and bosses to the fiber-reinforced resin, improving its design.

[0021] 4. Effect of metal strip aggregation (iii) The shielding layer precursor 20 also contains a second matrix resin 40. The inclusion of the second matrix resin makes it easier to provide ribs, bosses, etc. to the shielding layer when integrally molding the fiber reinforced resin 10 and the shielding layer precursor 20. When only a metal plate is provided as a separate part, as in the past, it is not possible to form the shielding layer into a complex shape.

[0022] 5. Effect of metal strip aggregation (iv) The shielding layer precursor 20 is embedded in the integrally molded body, and it is preferable that the surface of the integrally molded body and the surface of the shielding layer are flush with each other. In this case, there is no step at the interface between the integrally molded body and the shielding layer, resulting in a flat shape. The interface may be flush with the top surface or the vertical surface of the integrally molded body. Since the edges of the shielding layer are embedded in resin during integral molding, chipping at the edges of the shielding layer can also be reduced.

[0023] [Shielding layer: metal strip] The metal strip preferably has a width of 1 mm to 40 mm, a length of 1 mm to 100 mm, and a thickness of 100 μm or less. A width of 1 mm or more makes slitting easier. More preferably, the metal strip has a width of 1 mm to 40 mm, a length of 1 mm to 40 mm, and a thickness of 100 μm or less.

[0024] The width of the metal strip is more preferably 2 mm to 20 mm, even more preferably 2 mm to 7 mm, and even more preferably 2 mm to 5 mm.

[0025] The length of the metal strip is more preferably 2 mm to 20 mm, even more preferably 2 mm to 7 mm, and even more preferably 2 mm to 5 mm.

[0026] The thickness of the metal strip is preferably 70 μm or less, more preferably 50 μm or less, and even more preferably 30 μm or less. The lower limit of the thickness of the metal strip is preferably 12 μm or more, and more preferably 15 μm or more. The metal strip may also be in the form of a rectangular strip. The weight of each metal strip is preferably 0.001 g to 0.050 g, more preferably 0.003 g to 0.040 g, and even more preferably 0.005 g to 0.020 g. Specifically, for a metal strip with a width of 5 mm, a length of 20 mm, and a thickness of 30 μm, the weight is approximately 0.008 g. When light metal strips like this are dispersed, some of them stand upright instead of tipping over. Specifically, less than 1% of the metal thin film will stand upright (for example, 901 in Figure 4). Here, "standing" metal strips means that their thickness direction is oriented horizontally. Standing metal strips will be crushed during integral molding.

[0027] [Shielding layer: mass fraction of metal strips W(metal)] The mass fraction W(metal) of the aggregate of metal strips in the shielding layer is preferably 30% or more, more preferably 50% or more, and even more preferably 70% or more. The mass fraction W(metal) of the aggregate of metal strips is the ratio of the mass of the metal strips to the total mass including not only the metal strips and second matrix resin but also other additives.

[0028] The mass ratio W(metal) is measured by burning off the resin in a furnace at 500°C for 1 hour when the second matrix resin contained in the shielding layer is polypropylene resin, and then weighing the mass of the shielding layer and metal strip assembly before and after the treatment. Next, the volume ratio of the metal strip assembly, resin, and other additives can be calculated using the specific gravity of each component. Mass ratio W (metal) = 100 × mass of metal strip aggregate / (mass of metal strip aggregate + mass of resin + other additives)

[0029] [Shielding layer: randomly distributed in the in-plane direction] FIG. 3 is a plan view showing an example of the shielding layer precursor 20. As shown in FIG. 3, the metal strips are dispersed in the in-plane direction of the shielding layer precursor 20. Here, "dispersed in the in-plane direction" of the metal strips means that the thickness direction of the metal strips is substantially the same as the thickness direction of the shielding layer, and the length direction of the metal strips is oriented in a random direction within the plane of the shielding layer. In the region where the shielding layer precursor 20 is press-formed without flow, the shape of the metal strips is largely maintained before and after forming. Therefore, the metal strips contained in the non-flowing region of the shielding layer precursor are also preferably dispersed in the in-plane direction, and more preferably randomly dispersed. "Randomly dispersed" refers to a state in which the metal strips are oriented randomly within the in-plane direction of the shielding layer precursor or the shielding layer, rather than in a specific direction such as one direction, and are arranged within the plane overall without any specific directionality. When preparing the assembly of metal strips, even if some of the metal strips are laid on their side (with the thickness direction of the metal strips facing in the in-plane direction of the shielding layer) (for example, 901 in Figure 4), when the shielding layer precursor is press-molded, the metal strips will be dispersed in the in-plane direction within the molded shielding layer.

[0030] [Shielding layer: Shielding of electric or magnetic fields] 1. The shielding layer shields against at least one of electric and magnetic fields, and preferably has an electric or magnetic field shielding property of 10 decibels or more in at least a portion of the frequency range from 0 MHz to 3000 MHz. The electric or magnetic field shielding property is more preferably 20 decibels or more, and even more preferably 30 decibels or more. Here, the shielding property can be expressed as 10 times the common logarithm (in decibels) of the ratio of the power of the electromagnetic wave before passing through the shielding layer to the power of the electromagnetic wave after passing through the shielding layer.

[0031] As a preferred range for each shielding region, the electric or magnetic field shielding property is preferably 10 dB or more in at least 50% of the region from above 0 MHz to 3000 MHz. The electric or magnetic field shielding property is more preferably 20 dB or more, and even more preferably 30 dB or more. "In at least 50% of the region from above 0 MHz to 3000 MHz" means that the shielding region may be continuous or discontinuous in the region from above 0 MHz to 3000 MHz.

[0032] As a preferred range for each shielding region, the electric or magnetic field shielding property is preferably 10 dB or more in all regions from over 0 MHz to 3000 MHz, more preferably 20 dB or more, and even more preferably 30 dB or more.

[0033] 2. More preferable shielding properties will be explained below. The shielding layer shields at least one of electric and magnetic fields, and the shielding ability against the electric or magnetic field is preferably 10 dB or more in at least a part of the frequency range from 0 MHz to 100 MHz, more preferably 20 dB or more, and even more preferably 30 dB or more.

[0034] As a preferred range for each shielding region, the electric or magnetic field shielding property is preferably 10 dB or more in at least 50% of the region from more than 0 MHz to 100 MHz. The electric or magnetic field shielding property is more preferably 20 dB or more, and even more preferably 30 dB or more. "In at least 50% of the region from more than 0 MHz to 100 MHz" means that the shielding region may be continuous or discontinuous in the region from more than 0 MHz to 100 MHz.

[0035] As a preferred range for each shielding region, the electric or magnetic field shielding property is preferably 10 dB or more in all regions from over 0 MHz to 100 MHz, more preferably 20 dB or more, and even more preferably 30 dB or more.

[0036] The shielding performance will be explained using the graphs in Figures 5A to 5F. Figure 5A is a graph of the electric field shielding performance of a 150-µm-thick polypropylene resin layer. Figure 5B is a graph of the electric field shielding performance of a 150-µm-thick shielding layer containing an aluminum thin film and polypropylene resin when the mass fraction W of the aluminum thin film is 25%. Figure 5C is a graph of the electric field shielding performance of a 150-µm-thick shielding layer containing an aluminum thin film and polypropylene resin when the mass fraction W of the aluminum thin film is 45%. Figure 5D is a graph of the electric field shielding performance of a 150-µm-thick shielding layer containing an aluminum thin film and polypropylene resin when the mass fraction W of the aluminum thin film is 65%. Figure 5E is a graph of the electric field shielding performance of a 150-µm-thick shielding layer containing an aluminum thin film and polypropylene resin when the mass fraction W of the aluminum thin film is 75%. Figure 5F is a graph of the electric field shielding performance of a 150-µm-thick aluminum thin film. 5A to 5F, the horizontal axis represents frequency (Hz) and the vertical axis represents decibels (dB). 5 :1.00E+05) or more 100MHz (10 8 In the region between 0.1 MHz and 100 MHz (1.00E+08) and below (the region indicated by the arrow 801 in FIG. 8A), no electric field is shielded at all. In the region of 0.1 MHz or higher and 100 MHz or lower in FIG. 5B, an electric field shielding performance of approximately 20 dB is shown. In the region of 0.1 MHz or higher and 100 MHz or lower in FIG. 5C, an electric field shielding performance of approximately 33 dB is shown. In the region of 0.1 MHz or higher and 100 MHz or lower in FIG. 5D, an electric field shielding performance of approximately 35 to 50 dB is shown. In the region of 0.1 MHz or higher and 100 MHz or lower in FIG. 5E, an electric field shielding performance of approximately 35 to 76 dB is shown. In the region of 0.1 MHz or higher and 100 MHz or lower in FIG. 5F, an electric field shielding performance of approximately 35 to 122 dB is shown.

[0037] Shielding layer thickness In the present invention, there is no particular limitation on the thickness tx of the shielding layer, as long as it is equal to or greater than the thickness ty of the metal strip. Ideally, the shielding layer should have a thickness tx equal to the thickness ty of one metal strip. Increasing the thickness of the shielding layer does not significantly improve the shielding properties. This is because, if the thickness ty of the metal strip is 10 μm or greater, it is considered that the thickness dependency of the shielding layer in improving the shielding properties is low.

[0038] However, from the viewpoint of preventing gaps, it is preferable to reduce the thickness of the metal strips and increase the density of the assembly (increase the number of metal strips per unit area), and therefore, when the thickness of the shielding layer is tx and the thickness of the metal strip is ty, it is preferable to have a portion that satisfies 2≦tx / ty, more preferably to have a portion that satisfies 3≦tx / ty, and even more preferably to have a portion that satisfies 5≦tx / ty. Note that if the thickness of the shielding layer is different between the vertical surface portion and the top surface portion in the integrally molded body, and the shielding layer is not uniform in thickness, it is preferable that any one of the portions is within the above range.

[0039] [Shielding layer: reinforced fiber] Reinforcing fibers may be added to the shielding layer to prevent the metal strips from breaking apart and draping down when the shielding layer is subjected to a fire test. Furthermore, the inclusion of reinforcing fibers in the shielding layer improves ductility. Aramid fiber, glass fiber, or carbon fiber is preferred as the reinforcing fiber to be mixed into the shielding layer.

[0040] [Shielding layer: manufacturing method of shielding layer precursor] The integrally molded body of the present invention is preferably produced by laminating a fiber-reinforced resin containing reinforcing fibers and a first matrix resin with a shielding layer precursor, and press-molding the laminate using an upper molding die and a lower molding die (sometimes collectively referred to as upper and lower molding dies). That is, the shielding layer is obtained by molding the shielding layer precursor. There are no particular limitations on the method for producing the shielding layer precursor, but it can be produced as follows.

[0041] 1. Metal Strip Assembly Preparation 1.1 Slit The assembly of metal strips can be produced by slitting a wide metal film and then cutting it. 1.1.1 Roller pressing slit (Fig. 6) Figure 6 is a schematic diagram showing how a thin metal film is pressed against a support roller (rubber roller 503) shown in Figure 6 and slit with blade 502 to produce a thin bundle of metal strips 501. As shown in Figure 6, the thin metal film is pressed against high-hardness rubber roller 503 that has been heat-treated, such as quenched, to slit it. In this case, adjustments must be made to prevent scratches on rubber roller 503 so that the thin metal film does not get pinched.

[0042] 1.1.2 Slitting with a shear blade (Figs. 7 to 9) 7 to 9 are schematic diagrams showing how a metal thin film 603 is slit using a shear blade method. FIG. 7 is a side view showing how the metal thin film 603 passes between an upper rotary blade 601 and a lower rotary blade 602, FIG. 8 is a cross-sectional view taken along line VIII-VIII in FIG. 7, and FIG. 9 is an enlarged view of part IX in FIG. 8. As shown in FIGS. 7 to 9, the upper rotary blade 601 is provided with a sharp cutting edge 604 with a clearance angle, and the metal thin film 603 is pressed against the side of the tip 605 of the lower rotary blade 602 to slit the blades. In this case, highly accurate clearance management is required over time.

[0043] 1.1.3 Gang system (Figures 10 to 12) 10 to 12 are schematic diagrams illustrating the separation of a reinforcing fiber bundle using the gang method. Fig. 10 is a side view showing the state in which a metal thin film 673 passes between an upper rotary blade 701 and a lower rotary blade 702. Fig. 11 is a cross-sectional view taken along line XI-XI in Fig. 10, and Fig. 12 is an enlarged view of portion XII in Fig. 11. As shown in Figs. 10 to 12, the upper blade 704 provided on the upper rotary blade 701, which is a rotating circular blade, and the lower blade 705 provided on the lower rotary blade are combined in a configuration in which their tips overlap with a small gap between them. The reinforcing fiber bundle is sandwiched between the overlapping portions, and the shear force of the overlapping portion of the upper and lower blades separates the bundle. As with the shear blade method, highly accurate clearance management is required over time.

[0044] 1.2 Cutting slit metal strips The slit metal strip is cut to a fixed length using, for example, a rotary cutter, and then spread and fixed onto a resin previously prepared on a breathable support that moves continuously in one direction and has a suction mechanism underneath, placed directly below the rotary cutter, to obtain an aggregate of metal strips. The resin is preferably in the form of a film or nonwoven fabric.

[0045] 2. Second matrix resin The metal thin film in the shielding layer is fixed by a second matrix resin. The second matrix resin contained in the shielding layer may be thermosetting or thermoplastic. It is preferable that the first matrix resin and the second matrix resin are the same resin. Hereinafter, the first matrix resin will also be referred to as resin A, and the second matrix resin will also be referred to as resin B.

[0046] 2.1. Thermoplastic resin When the resin used as the first matrix resin or the second matrix resin is a thermoplastic resin, the type of the resin is not particularly limited, and a resin having a desired softening point or melting point can be appropriately selected and used. As the thermoplastic resin, one having a softening point in the range of 180°C to 350°C is usually used, but is not limited thereto.

[0047] Examples of thermoplastic resins include polyolefin resins, polystyrene resins, polyamide resins, polyester resins, polyacetal resins (polyoxymethylene resins), polycarbonate resins, (meth)acrylic resins, polyarylate resins, polyphenylene ether resins, polyimide resins, polyethernitrile resins, phenoxy resins, polyphenylene sulfide resins, polysulfone resins, polyketone resins, polyether ketone resins, thermoplastic urethane resins, fluorine-based resins, and thermoplastic polybenzimidazole resins.

[0048] The thermoplastic resin used in the integrally molded article of the present invention may be one type only, or two or more types. Examples of the use of two or more types of thermoplastic resins in combination include, but are not limited to, the use of thermoplastic resins having different softening points or melting points, or the use of thermoplastic resins having different average molecular weights. When a thermoplastic resin is used, it is more preferable to use a polyolefin resin, and even more preferable to use a polypropylene resin.

[0049] 2.2. Thermosetting resin The first matrix resin may be a thermosetting resin. When a thermosetting resin is used, it is preferably an unsaturated polyester resin, a vinyl ester resin, an epoxy resin, or a phenol resin. One type of resin may be used alone, or two or more types may be used in combination.

[0050] Alternatively, fiber-reinforced resins may be made from sheet molding compounds (sometimes called SMCs) containing reinforcing fibers. Sheet molding compounds have high moldability, making them easy to mold into even complex shapes. Compared to continuous fiber, sheet molding compounds have higher fluidity and formability, making it easy to create ribs and bosses.

[0051] 3. Welding of a collection of metal strips The assembly of metal strips is then sandwiched between resin from above to create a three-layer laminate of "resin / assembly of metal strips / resin." If the resin is a thermoplastic resin, the shielding layer precursor is completed by melting the resin and fusing it to the metal strips. At this time, resin may or may not be present between the aggregate of metal strips. In order to improve the welding strength between the metal strips, a binder may be applied to the metal strips in advance.

[0052] In this embodiment, the assembly of metal strips is sandwiched and welded using polypropylene resin. The formed shielding layer precursor 20 may be used alone for integral molding with the fiber reinforced resin 10, or two or more shielding layer precursors 20 may be laminated or used separately for integral molding with the fiber reinforced resin 10 without lamination.

[0053] [Shielding layer: Ductility] Ductility refers to the property of a substance being able to deform under an external force and continue to stretch without being broken. Generally, when an external force is applied to a substance, deformation occurs, and the substance is stretched by the continuous deformation. For example, metals have high ductility and can be stretched into a long and thin shape when pulled. This property is utilized in the processing of metal products and the manufacture of wires, etc. On the other hand, brittle substances such as glass and ceramics have low ductility and tend to be easily broken when an external force is applied. Generally, the formability of metals is inferior to that of resins.

[0054] In the integral molded body of the present invention, the relationship between the ductility E1 of the fiber reinforced resin and the ductility E2 of the laminate of the fiber reinforced resin and the shielding layer precursor is preferably 0.9 < E1 / E2 < 50, more preferably 1 < E1 / E2 < 20, still more preferably 1 < E1 / E2 < 10, and even more preferably 1 < E1 / E2 < 7.

[0055] In the present invention, it is preferable that the fiber reinforced resin is in a plate shape, and the shielding layer precursor flows and spreads in the in-plane direction of the fiber reinforced resin to manufacture a press-molded body. Also, in the present invention, the ductility of the fiber reinforced resin is preferably more than 1% and 300% or less, and more preferably more than 20% and 150% or less.

[0056] The ductility of the laminate of the fiber reinforced resin and the shielding layer precursor is preferably more than 2% and 100% or less, and more preferably more than 10% and less than 80%. Mixing reinforcing fibers in the shielding layer precursor improves the ductility. Also, it is preferable that E1 > E2. When the values of E1 and E2 are close, it is easy to mold the integral molded body. The method for measuring ductility will be described later. Note that ductility is sometimes called elongation rate and is expressed as a percentage.

[0057] [Shielding layer: Comparison with continuous fiber net] One method for making the shielding layer conform to the fiber-reinforced resin is to use continuous metal fibers capable of shielding electric or magnetic fields, form them into a net shape, and laminate them with the fiber-reinforced resin to create an integrally molded body. By forming them into a net shape, the ductility of the shielding layer precursor can be made closer to that of the fiber-reinforced resin, improving moldability. However, if the shielding layer precursor is prepared by forming continuous metal fibers into a net shape, the mesh (spaces) of the net will widen during the molding process (also known as gap widening), resulting in reduced shielding performance. The shielding layer of the present invention can reduce the effect of the shielding layer lowering before and after molding.

[0058] [Fiber-reinforced resin layer: Reinforced fiber] In this specification, the reinforcing fiber is preferably at least one selected from the group consisting of carbon fiber, aramid fiber, and glass fiber, and more preferably carbon fiber or glass fiber.

[0059] [Fiber-reinforced resin layer: Reinforced fiber (carbon fiber)] 1. Carbon fiber in general When carbon fibers are used, polyacrylonitrile (PAN)-based carbon fibers, petroleum / coal pitch-based carbon fibers, rayon-based carbon fibers, cellulose-based carbon fibers, lignin-based carbon fibers, phenol-based carbon fibers, etc. are generally known, and any of these carbon fibers can be suitably used in the present invention. Among these, polyacrylonitrile (PAN)-based carbon fibers are preferred in the present invention because of their excellent tensile strength. As a PAN-based carbon fiber, for example, TENAX (registered trademark) STS40-24KS (average fiber diameter 7 μm) carbon fiber manufactured by Teijin Limited can be used.

[0060] 2. Carbon fiber sizing agent The carbon fiber used in the present invention may have a sizing agent attached to its surface. When using carbon fiber with a sizing agent attached, the type of sizing agent can be appropriately selected depending on the type of carbon fiber and the type of resin, and is not particularly limited.

[0061] [Fiber-reinforced resin layer: Reinforced fiber (glass fiber)] The case where the reinforcing fiber used in the present invention is glass fiber will be described. 1. Glass fiber in general The glass fiber used in the present invention may be any glass fiber generally referred to as glass fiber. The glass composition is not particularly limited, and may include A-glass, C-glass, E-glass, etc., and may contain components such as TiO2, SO3, and P2O5 in some cases. For example, Nitto Boseki's E-glass RS240QR-483 (count: 2400 g / 1000 m) glass fiber can be used as the glass fiber.

[0062] 2.Glass fiber sizing agent The glass fiber used in the present invention may have a sizing agent attached to its surface. When using glass fiber with a sizing agent attached, the type of sizing agent can be appropriately selected depending on the type of glass fiber and the type of resin, and is not particularly limited. Glass fiber that has been pre-treated with a conventionally known coupling agent such as an organosilane compound, an organotitanium compound, an organoborane compound, or an epoxy compound can be preferably used.

[0063] [Fiber-reinforced resin layer: Reinforced fibers dispersed in the in-plane direction] The reinforcing fibers of the present invention are preferably discontinuous fibers and dispersed in the in-plane direction of the fiber-reinforced resin layer. Furthermore, in order to disperse the reinforcing fibers in the in-plane direction in the fiber-reinforced resin layer, it is preferable to disperse the reinforcing fibers contained in the fiber-reinforced resin in the in-plane direction. Dispersing the reinforcing fibers in the in-plane direction means dispersing the reinforcing fibers so that their fiber axes are oriented in the in-plane direction. It is preferable that the angle between the fiber axes of the reinforcing fibers and the in-plane direction is 45° or less.

[0064] 1. In-plane direction The in-plane direction is an indefinite direction of a parallel plane perpendicular to the plate thickness direction of the fiber reinforced resin or fiber reinforced resin layer. The fiber reinforced resin is preferably a plate-shaped material.

[0065] 2. Random distribution in two dimensions It is preferable that the reinforcing fibers are randomly dispersed in the in-plane direction and in two dimensions. In the region where the fiber-reinforced resin is press-molded without flowing, the shape of the reinforcing fibers is almost maintained before and after molding. Therefore, it is preferable that the reinforcing fibers contained in the non-flow region of the fiber-reinforced resin layer formed from the fiber-reinforced resin are also randomly dispersed in the in-plane direction and in two dimensions.

[0066] Here, "two-dimensionally randomly dispersed" refers to a state in which the reinforcing fibers are oriented randomly within the in-plane direction of the fiber-reinforced resin or fiber-reinforced resin layer, rather than in a specific direction such as one direction, and are arranged within the sheet plane overall without showing any specific directional preference. A fiber-reinforced resin or fiber-reinforced resin layer obtained using such two-dimensionally randomly dispersed discontinuous fibers does not have anisotropy within the plane and is substantially isotropic.

[0067] The degree of two-dimensional random orientation is evaluated by determining the ratio of the tensile modulus in two mutually perpendicular directions. If the ratio (Eδ) obtained by dividing the larger of the tensile modulus values ​​measured in any direction of the fiber-reinforced resin or fiber-reinforced resin layer by the smaller of the measured values ​​is 5 or less, more preferably 2 or less, and even more preferably 1.5 or less, the reinforcing fibers can be evaluated as being two-dimensionally randomly dispersed.

[0068] When the resin contained in the fiber-reinforced resin layer is a thermoplastic resin and the fiber-reinforced resin layer has a three-dimensional shape including curved surfaces, a method for evaluating two-dimensional random dispersion in the in-plane direction is to heat the fiber-reinforced resin layer above its softening temperature, return it to a flat plate shape, and then solidify it. After that, test specimens can be cut out and the tensile modulus measured to confirm the state of random dispersion in the two-dimensional direction.

[0069] [Fiber reinforced resin layer: fiber length of reinforcing fibers] The reinforcing fibers are preferably discontinuous fibers. When discontinuous fibers are used, formability is improved compared to fiber-reinforced plastics that use only continuous fibers, making it easier to create complex fiber-reinforced resin layers. Since the weight-average fiber length of the reinforcing fibers does not change before and after molding, the weight-average fiber length Lw of the reinforcing fibers contained in the fiber-reinforced resin can be determined by examining the weight-average fiber length of the reinforcing fibers in the fiber-reinforced resin layer.

[0070] The weight-average fiber length Lw of the reinforcing fibers is preferably 1 mm or more, and more preferably 3 mm or more. The weight-average fiber length Lw of the reinforcing fibers is more preferably 3 mm or more and 100 mm or less, more preferably 3 mm or more and 80 mm or less, and even more preferably 5 mm or more and 60 mm or less. If the weight-average fiber length Lw of the reinforcing fibers is 100 mm or less, the fluidity of the fiber-reinforced resin is less likely to decrease when the fiber-reinforced resin is produced by press molding, and it is easy to produce the desired shape. Furthermore, if the weight-average fiber length Lw is 1 mm or more, the mechanical strength of the resulting fiber-reinforced resin member is less likely to decrease, which is preferable.

[0071] The weight average fiber length Lw and number average fiber length Ln of the reinforcing fibers can be calculated by the formulas (1) and (2) described below. In a fiber-reinforced resin layer produced by injection molding, the weight-average fiber length of the reinforcing fibers is about 0.1 to 0.3 mm. Therefore, when the weight-average fiber length of the reinforcing fibers is set to 1 mm or more and 100 mm or less, it is preferable to produce the fiber-reinforced resin layer by press molding.

[0072] In the present invention, discontinuous reinforcing fibers having different fiber lengths may be used in combination. In other words, the discontinuous reinforcing fibers used in the present invention may have a single peak in the weight-average fiber length distribution, or may have multiple peaks.

[0073] [Fiber-reinforced resin layer: number-average fiber length Ln and weight-average fiber length Lw of reinforcing fibers] Generally, if the fiber length of each reinforcing fiber is Li, the number average fiber length Ln and weight average fiber length Lw can be calculated by the following formulas (1) and (2). The units of the number average fiber length Ln and weight average fiber length Lw are mm.

number

[0074] When the fiber length is constant, the number-average fiber length and the weight-average fiber length are the same value. Reinforcing fibers can be extracted from the fiber-reinforced resin layer by, for example, performing a heat treatment at 500°C for about 1 hour and removing the resin in a furnace.

[0075] The average fiber length can be calculated, for example, by measuring the fiber lengths of 100 fibers randomly extracted from the fiber-reinforced resin layer to the nearest 1 mm using a vernier caliper or the like, and then calculating the average fiber length based on formula (1) or formula (2). If the dispersion contains short fibers that cannot be measured with a caliper, remove the resin, then place the resulting reinforcing fibers in water containing a surfactant and thoroughly stir using ultrasonic vibrations. Samples for evaluation can be obtained by randomly sampling the stirred dispersion with a measuring spoon, and measuring the lengths of 3,000 fibers using a Nireco Luzex AP image analyzer. The measured fiber lengths can be used to calculate the number-average fiber length Ln and weight-average fiber length Lw using the same formulas (1) and (2) described above.

[0076] [Fiber reinforced resin layer: fiber volume ratio of reinforcing fibers] Although there is no particular limitation on the fiber volume fraction Vf of the reinforcing fibers, it is preferably 20 to 70%, more preferably 25 to 60%, and even more preferably 30 to 55%. The fiber volume fraction (Vf, unit: volume %) is the ratio of the volume of the reinforcing fibers to the total volume including not only the reinforcing fibers and resin but also other additives.

[0077] Although there is no limitation on the analysis of the reinforcing fiber volume fraction, it is recommended to measure it as follows. A sample is cut from the fiber-reinforced resin layer, and the resin is burned off in a furnace at 500°C for 1 hour. The mass of the sample is then weighed before and after treatment to calculate the mass of the reinforcing fiber, resin, and other additives. Next, the volume ratio of the reinforcing fiber to the resin is calculated using the specific gravity of each component. Vf = 100 x reinforcing fiber volume / (reinforcing fiber volume + resin volume + other additives)

[0078] [Fiber reinforced resin layer: first matrix resin] The first matrix resin contained in the fiber reinforced resin layer may be thermosetting or thermoplastic. 1.Thermoplastic resin When the resin used is a thermoplastic resin, the type is not particularly limited, and a resin having a desired softening point or melting point can be appropriately selected and used. As the thermoplastic resin, one having a softening point in the range of 180°C to 350°C is usually used, but is not limited thereto.

[0079] Examples of thermoplastic resins include polyolefin resins, polystyrene resins, polyamide resins, polyester resins, polyacetal resins (polyoxymethylene resins), polycarbonate resins, (meth)acrylic resins, polyarylate resins, polyphenylene ether resins, polyimide resins, polyethernitrile resins, phenoxy resins, polyphenylene sulfide resins, polysulfone resins, polyketone resins, polyether ketone resins, thermoplastic urethane resins, fluorine-based resins, and thermoplastic polybenzimidazole resins.

[0080] The thermoplastic resin used in the fiber-reinforced resin layer of the present invention may be one type or two or more types. Examples of the use of two or more types of thermoplastic resins in combination include, but are not limited to, the use of thermoplastic resins having different softening points or melting points, or the use of thermoplastic resins having different average molecular weights. When a thermoplastic resin is used, it is more preferable to use a polyolefin resin, and it is even more preferable to use a polypropylene resin.

[0081] 2.Thermosetting resin The first matrix resin may be a thermosetting resin. When a thermosetting resin is used, it is preferably an unsaturated polyester resin, a vinyl ester resin, an epoxy resin, or a phenol resin. One type of resin may be used alone, or two or more types may be used in combination.

[0082] Alternatively, fiber-reinforced resins may be made from sheet molding compounds (sometimes called SMCs) containing reinforcing fibers. Sheet molding compounds have high moldability, making them easy to mold into even complex shapes. Compared to continuous fiber, sheet molding compounds have higher fluidity and formability, making it easy to create ribs and bosses.

[0083] [Fiber reinforced resin layer: Other agents] The first matrix resin used in the fiber-reinforced resin may contain additives such as various fibrous or non-fibrous fillers, such as organic or inorganic fibers, flame retardants, UV-resistant agents, stabilizers, mold release agents, pigments, softeners, plasticizers, and surfactants, as long as the object of the present invention is not impaired. When a thermosetting resin is used, it may also contain thickeners, curing agents, polymerization initiators, polymerization inhibitors, and the like. One type of additive may be used alone, or two or more types may be used in combination.

[0084] [Thermoplastic resins and non-flow molding] The first matrix resin and the second matrix resin of the present invention are preferably the same type of thermoplastic resin. Furthermore, since the shielding layer precursor needs to be molded following the fiber-reinforced resin, it is preferable that the fiber-reinforced resin is not flow-molded during molding. More preferably, the first matrix resin and the second matrix resin are the same type of thermoplastic resin, and the area charge ratio of the fiber-reinforced resin relative to the total area of ​​the mold cavity is 80% or more. Even more preferably, the area charge ratio of the shielding layer precursor relative to the total area of ​​the mold cavity is 80% or more.

[0085] [Manufacturing method: integral molding] The integrally molded body of the present invention is an integrally molded body of a fiber-reinforced resin layer containing reinforcing fibers and a first matrix resin, and a shielding layer. The integrally molded body is a body obtained by integrally molding the fiber-reinforced resin layer containing reinforcing fibers and a first matrix resin, and the shielding layer. Here, integral molding means that these are molded continuously without any seams, and are not molded by joining separate components together. Such integral molding is produced in a single molding operation, preferably by press molding. Because it is produced by integral molding, separate parts can be processed as a single part, making it possible to reduce the unit price of the part. In addition, the number of assembly steps is reduced, and the reduction in the number of parts also makes it possible to reduce inventory costs.

[0086] [Manufacturing method: press molding] The integrally molded body of the present invention may be produced by laminating a fiber reinforced resin containing reinforcing fibers and a first matrix resin and a shielding layer precursor, and press-molding the laminate using upper and lower molding dies. More specifically, when the first matrix resin and the second matrix resin are thermoplastic resins, the fiber reinforced resin and the shielding layer precursor are heated, the heated fiber reinforced resin and the shielding layer precursor are stacked together, and pressed simultaneously in a molding die to produce an integrally molded body.

[0087] 1. Fiber-reinforced resin and shielding layer precursor There are no particular limitations on the method for stacking the fiber reinforced resin and the shielding layer precursor, but since the shielding layer precursor has high conformability to the fiber reinforced resin, it is preferable to stack them together with the same size. Although there are no particular limitations on the volume ratio of the fiber-reinforced resin Vx to the shielding layer precursor Vy, Vx:Vy is preferably 99:1 to 60:40, and more preferably 98:2 to 66:34. Within this range, the shielding layer does not become too thick and has good moldability.

[0088] 2. Hot press molding and cold press molding As the molding method in the present invention, press molding (sometimes called compression molding) is used, and molding methods such as hot press molding and cold press molding can be used.

[0089] 2.1 Cold press molding When a thermoplastic resin is used as the resin, press molding using cold press is preferred. In cold press molding, for example, a fiber-reinforced resin and a shielding layer precursor heated to a first predetermined temperature are placed in a mold set to a second predetermined temperature, and then pressurized and cooled.

[0090] Specifically, when the thermoplastic resin constituting the fiber reinforced resin or the shielding layer precursor is crystalline, the first predetermined temperature is equal to or higher than the melting point, and the second predetermined temperature is lower than the melting point. When the thermoplastic resin is amorphous, the first predetermined temperature is equal to or higher than the glass transition temperature, and the second predetermined temperature is lower than the glass transition temperature. That is, the cold pressing method includes at least the following steps A-1) to A-2). Step A-1) A step of heating the thermoplastic resin to a temperature above the melting point but below the decomposition temperature if the thermoplastic resin is crystalline, or above the glass transition temperature but below the decomposition temperature if the thermoplastic resin is amorphous. Step A-2) The fiber-reinforced resin and the shielding layer precursor heated in Step A-1) are placed in a mold whose temperature is adjusted to below the melting point if the thermoplastic resin is crystalline, or below the glass transition temperature if the thermoplastic resin is amorphous, and then pressurized. By performing these steps, the molding of the fiber-reinforced resin and the shielding layer precursor can be completed (a press-molded body can be produced).

[0091] The above steps must be performed in the order described above, but other steps may be included between each step, such as a shaping step, which is performed before step A-2), in which a shaping mold different from the mold used in step A-2) is used to pre-shape the mixture into the shape of the cavity of the mold. The shape of at least one of the fiber reinforced resin and the shielding layer precursor may be a shape developed by computer through inverse molding analysis from the three-dimensional shape of the press-molded body to be produced.

[0092] 2.2 Hot press molding In the hot press molding method, for example, a fiber-reinforced resin is placed in a mold, pressure is applied while the temperature of the mold is increased to a first predetermined temperature, and the mold is cooled to a second predetermined temperature. Specifically, if the thermoplastic resin constituting the fiber-reinforced resin and the shielding layer precursor is crystalline, the first predetermined temperature is equal to or higher than the melting point, and the second predetermined temperature is lower than the melting point. If the thermoplastic resin constituting the fiber-reinforced resin and the shielding layer precursor is amorphous, the first predetermined temperature is equal to or higher than the glass transition temperature, and the second predetermined temperature is lower than the glass transition temperature.

[0093] The hot press molding preferably includes at least the following steps B-1) to B-4). B-1) A step of placing the fiber reinforced resin and the shielding layer precursor in a molding die (lower die). B-2) A process of applying pressure while heating the mold to a temperature above the melting point and below the thermal decomposition temperature of the thermoplastic resin if the thermoplastic resin is crystalline, or to a temperature above the glass transition temperature and below the thermal decomposition temperature of the thermoplastic resin if the thermoplastic resin is amorphous (first pressing process). B-3) A process of applying pressure in one or more stages, with the pressure in the final stage being 1.2 to 100 times the pressure in the first pressing process (second pressing process). B-4) A step of adjusting the mold temperature to below the melting point if the thermoplastic resin is crystalline, or below the glass transition temperature if the thermoplastic resin is amorphous. By carrying out these steps, an integrally molded body can be produced.

[0094] 3. Commonalities between cold press molding and hot press molding Steps A-2) and B-3) are steps in which pressure is applied to the fiber-reinforced resin and the shielding layer precursor to obtain a molded body of the desired shape. The molding pressure at this time is not particularly limited, but it is preferably as low as possible within a range in which the desired structural shape can be obtained. Specifically, the pressure is preferably less than 30 MPa relative to the mold cavity projected area, more preferably 20 MPa or less, and even more preferably 10 MPa or less. A molding pressure of less than 30 MPa is preferable because it does not require capital investment or maintenance costs for a press. Naturally, various processes may be inserted between the above steps during compression molding, and for example, vacuum compression molding, in which compression molding is performed under vacuum, may be used.

[0095] 4. Arrangement of fiber reinforced resin and shielding layer precursor (layering order) There are no particular limitations on the stacking order of the fiber-reinforced resin and the shielding layer precursor, but when cold press molding is performed, it is preferable to place them in a mold so that the design surface comes into contact with the upper mold and then press mold them. For example, when the shielding layer is the design surface, it is preferable to stack the fiber-reinforced resin and the shielding layer precursor in this order in the mold so that the fiber-reinforced resin comes into contact with the lower mold and then perform cold press molding. In the case of cold press molding, if the material that forms the design surface (e.g., the shielding layer precursor) is not brought into contact with the lower mold, the thermoplastic resin that forms the design surface will not cool until just before pressing (until the material that forms the design surface comes into contact with the upper mold), making it easy to transfer the mirror surface of the mold.

[0096] [Manufacturing method: RTM molding] The integrally molded article of the present invention can also be produced using RTM (Resin Transfer Molding). For example, a woven fabric substrate using reinforcing fibers such as glass fiber or carbon fiber is first placed in a mold in a dry fabric state without a first matrix resin. At this time, a shielding layer precursor is placed on the dry fabric woven fabric substrate, and the mold is closed. Then, a thermosetting second matrix resin such as an epoxy resin with good fluidity (easily permeates the fibers) is filled in. Once the resin has spread, it is recommended to heat the mold to promote curing of the epoxy resin. This method also makes it possible to produce an integrally molded article in which a fiber-reinforced resin layer containing the reinforcing fibers of the present invention and a first matrix resin are integrally molded with a shielding layer.

[0097] It is also preferable to use a first matrix resin that hardens at a temperature lower than the softening temperature of the second matrix resin, because by setting the mold temperature for RTM molding lower than the softening temperature of the second matrix resin, the shielding layer is also solidified when molding of the fiber-reinforced resin layer is completed. If a first matrix resin that hardens at a temperature higher than the softening temperature of the second matrix resin is used, the mold temperature of the molding die for RTM molding can be set higher than the softening temperature of the second matrix resin to harden the first matrix resin, and then a process can be performed to lower the mold temperature to a temperature below the softening temperature of the second matrix resin, allowing the fiber-reinforced resin layer and the shielding layer to be demolded in a solidified state. In recent years, the development of resins with fast curing speeds has progressed, and RTM molding has contributed to the mass production of large composite products.

[0098] [Shape of integrally molded body] The integrally molded body 1A has a flat surface and a vertical surface. Specifically, it preferably has at least one flat surface having at least one thickness (plate thickness). The integrally molded body may have a three-dimensional shape including a T-shaped, L-shaped, U-shaped, or hat-shaped cross section, and may further have an uneven shape (for example, a rib, a boss, etc.).

[0099] FIG. 13 is a cross-sectional view showing an example of the integrally molded body 1A of an embodiment of the present invention. The integrally molded body 1A is obtained by molding the laminate 1 shown in FIG. 1. As shown in FIG. 13, the integrally molded body 1A manufactured according to the present invention preferably has a shape including a portion having a hat shape with a top surface portion 50 and a standing surface portion 60 in a cross-sectional shape. The top surface portion 50 is an example of a flat surface portion. For example, even in the case of a side door, a back door, or a roof for an automobile, it may have the standing surface portion and the top surface portion of the present invention.

[0100] It is preferable that the thickness ta of the standing surface portion of the integrally molded body 1A and the thickness tb of the top surface portion satisfy ta≦tb. It is more preferable that ta×0.8 < tb, and it is even more preferable that ta×0.6 < tb. For example, when using the plate-shaped shielding layer precursor 20 and the fiber reinforced resin 10, the thickness of the laminate 1 of the shielding layer precursor 20 and the fiber reinforced resin 10 is a uniform wall thickness. When creating a hat-shaped integrally molded body using this, the standing surface portion tends to be stretched by the mold and become thinner compared to the top surface portion.

[0101] On the other hand, in the integrally molded body 1A of the present invention, when making the thickness ta of the standing surface portion 60 and the thickness tb of the top surface portion the same thickness, when the thickness of the shielding layer 20A in the standing surface portion 60 is txa and the thickness of the fiber reinforced resin layer 10A is ta - txa, and the thickness of the shielding layer 20A in the top surface portion 50 is txb and the thickness of the fiber reinforced resin layer 10A is tb - txb, it is preferable to satisfy txa≦txb and ta - txa≧tb - txb. That is, since the fiber reinforced resin 10 has greater extensibility compared to the shielding layer precursor 20, the wall thickness of the standing surface portion 60 can be easily thickened during molding.

[0102] [Integrally Molded Body: Battery Tray and Battery Cover] The integrally molded body is preferably a vehicle structural body. Further, the vehicle structural body is preferably a component of the battery box, and the component of the battery box is preferably disposed at the lower part of the vehicle body. 14 is an exploded perspective view of a battery box 101 using the integrally molded body of this embodiment. The battery box 101 includes a battery cover 102, a battery 103, a temperature control system (cooling mechanism) 104, a battery tray 105, a reinforcing frame 106, and an energy absorbing member 107. The integrally molded body of this embodiment can be used for the battery cover 102 or the battery tray 105. The battery 103 is housed in the battery box 101 which includes the battery tray 105 and the battery cover 102.

[0103] [Battery Tray: General] The following describes the case where a battery tray is used as a vehicle structure. The battery tray 105 is for driving an automobile and is used to mount a battery 103 for driving the vehicle.

[0104] Fig. 15 is a perspective view of the battery tray 105, and Fig. 16 is a cross-sectional view taken along the line XVI-XVI in Fig. 15. As shown in Fig. 15 and Fig. 16, the battery tray 105 includes a first bottom surface portion 303 and a peripheral wall 203 erected on the outer periphery of the first bottom surface portion 303. The battery tray 105 also includes a first inner wall 204 connected to the first bottom surface portion 303, a second inner wall 205 connected to the first bottom surface portion 303, and a second bottom surface portion 301 connected to both the first inner wall 204 and the second inner wall 205 and raised from the first bottom surface portion. The first bottom surface portion 303, the peripheral wall 203, the first inner wall 204, the second inner wall 205, and the second bottom surface portion 301 are configured as part of the vehicle structure.

[0105] [Battery tray and shielding layer] When the vehicle structure is a battery box 101, the battery box 101 is provided with a shielding layer that shields electric or magnetic fields in order to shield electromagnetic waves generated from the battery 103. The shielding layer can block electromagnetic waves radiated from the battery 103 and prevent external radiation or leakage, ensuring sufficient electromagnetic wave shielding properties for the battery box and making it possible to suppress adverse effects of electromagnetic waves on the vehicle control system and the human body, for example.

[0106] [Shielding layer: conforms to recesses] For example, the shape of the battery box depicted in Figures 15 and 16 is complex, and there is a large recess such as 313 in Figure 15. How to cover such a recess is an issue, but if the shielding layer precursor of the present invention is used, it becomes easy to make the shielding layer conform to the shape of such a recess. [Example]

[0107] 2. Evaluation 2.1 Shielding A 150mm x 150mm test piece (flat plate) was sampled from the integrally molded body and the radio wave shielding ability for electric field waves (frequencies 0MHz to 100MHz) was measured using a network analyzer (manufactured by Keysight Technologies) and a KEC method measuring device (manufactured by JSE). The higher the value, the better the radio wave shielding ability. Good: The electric field shielding is 40 decibels or more in the entire range from 0 MHz to 100 MHz. Bad: The electric field shielding is 5 decibels or less in the entire range from 0 MHz to 100 MHz.

[0108] 2.2 Measurement of ductility of laminate of shielding layer precursor and fiber-reinforced resin 2.2.1 Measurement of molding heating temperature (1) Prepare a fiber-reinforced resin (or a laminate of a shielding layer precursor and fiber-reinforced resin) cut to a size of 200 mm x 200 mm. (2) As shown in Figure 17A, half of fiber-reinforced resin 1001 (or a laminate of shielding layer precursor and fiber-reinforced resin), measuring 100 mm x 200 mm, is placed on wire mesh 1002. Wire mesh 1002 is then placed on metal block mounting base 1003 and heated in an IR oven (infrared heater). The temperature at which the elastic modulus of the fiber-reinforced resin (or the laminate of shielding layer precursor and fiber-reinforced resin) decreases and the fiber-reinforced resin (or the laminate of shielding layer precursor and fiber-reinforced resin) sags 10 mm from its original height due to its own weight is measured and this temperature is defined as the softening temperature. The subsequent molding and heating temperature is defined as a temperature 50°C above this temperature.

[0109] 2.2.2 Press molding (1) The fiber-reinforced resin (or a laminate of the shielding layer precursor and the fiber-reinforced resin) heated to the molding heating temperature, which is the softening temperature + 50°C, is placed in a molding die having a spherical surface with a diameter of 150 mm in a plan view (Figure 17B). At this time, the diameter (φ150 mm) of the spherical surface when viewed in plan before the start of press forming is taken as the channel length before forming, La. This is press formed under the following conditions. Press lowering speed: 100mm / sec Mold clamping speed: 10mm / sec Forming load: 80 tons Mold: Open cavity Mold temperature: 60℃

[0110] (2) Next, samples with different post-molding path lengths Lb (for example, the arc length Lb in Figure 17C) are created by changing the lowering height of the upper mold. The obtained samples are visually inspected through the glass, and the maximum path length Lb of the sample for which no light leakage is observed is defined as the maximum expanded length. (3) Measure the ductility (%) using the following formula. Spreadability (%)=(Lb-La) / La × 100 (4) Extensibility of the fiber-reinforced resin and the laminate of the shielding layer precursor and the fiber-reinforced resin The ductility E1 of the fiber reinforced resin and the ductility E2 of the laminate of the fiber reinforced resin and the shielding layer precursor are calculated, and the value of E1 / E2 is calculated.

[0111] The thickness of the shielding layer precursor was regarded as the thickness tx of the shielding layer on the top surface after molding, and tx / ty was calculated.

[0112] [Example 1] 1. Shielding layer precursor As the thermoplastic resin for the first layer, a nonwoven fabric of polypropylene resin (Novatec (registered trademark) PPBC03C manufactured by Japan Polypropylene Corporation) was prepared. Next, a 20 cm wide, 0.012 mm thick aluminum foil (manufactured by UACJ Foil) was used as a thin metal film, which was slit using a rotary slit with a 3 mm pitch and then cut to a fixed length using a rotary cutter to obtain metal strips of 10 mm long, 3 mm wide, and 0.012 mm thick. These were then spread and fixed on a thermoplastic resin nonwoven fabric (the first layer of thermoplastic resin) that had been previously prepared on an air-permeable support that moved continuously in one direction and was placed directly below the rotary cutter, to obtain an assembly of metal strips.

[0113] Furthermore, polypropylene resin (Novatec PBC03C manufactured by Japan Polypropylene Corporation) was laid on top of the prepared assembly of metal strips using a feeder, and a second layer of thermoplastic resin was provided, resulting in a composite composition laminated in the order of first layer of thermoplastic resin / assembly of metal strips / second layer of thermoplastic resin. The prepared composite composition was heated at 2.0 MPa for 5 minutes in a press machine heated to 250°C, and then cooled to obtain a shielding layer precursor with a thickness of 0.15 mm and dimensions of 600 mm x 1000 mm.

[0114] 2. Fiber reinforced resin The glass fiber used was E-glass RS240QR-483 glass fiber manufactured by Nitto Boseki Co., Ltd., which was coated with a sizing agent and cut to a fiber length of 20 mm. The thermoplastic resin used was particulate polypropylene resin (Novatec PP BC03C manufactured by Japan Polypropylene Corporation) with an average particle size of approximately 710 μm. Based on the method described in US Pat. No. 8,946,342, a composite composition of glass fibers and polypropylene resin, in which the glass fibers are two-dimensionally randomly oriented, was prepared. Specifically, an air-permeable support that moves continuously in one direction and has a suction mechanism at the bottom was installed, and while suction was being performed by the suction mechanism, the above-mentioned glass fiber and polypropylene resin were blown onto the top of the air-permeable support using compressed air from a tapered tube located above the air-permeable support, creating a composite product in which the glass fiber and polypropylene resin were mixed. The resulting composite composition was heated at 250°C for 5 minutes at 2.0 MPa to produce a fiber-reinforced resin sheet measuring 600 mm x 1000 mm and with an average thickness of 3 mm. The properties of the shielding layer precursor and fiber-reinforced resin are summarized in Table 1.

[0115] 3. Cold Press The fiber-reinforced resin and the shielding layer precursor were heated to 220°C using an infrared heater. Then, one sheet of fiber-reinforced resin and one sheet of shielding layer precursor were stacked and placed in a molding die so that the fiber-reinforced resin was in contact with the lower molding die and the shielding layer precursor was in contact with the upper molding die. The upper die was lowered, and a press pressure of 20 MPa was applied for one minute (the time from the start of pressurization until the pressure reached 20 MPa was 1 second), simultaneously pressing the fiber-reinforced resin and the shielding layer precursor together to produce an integrally molded body with a top surface, a vertical surface, and corners formed by connecting the top and vertical surfaces. The results are shown in Table 1.

[0116] [Example 2] Except for using three sheets of the prepared shielding layer precursor, an integrally molded body was manufactured in the same manner as in Example 1. The results are shown in Table 1. [Example 3] An integrally molded body was produced in the same manner as in Example 1, except that glass fibers were mixed into the polypropylene resin of the shielding layer precursor so that the mass ratio was 10%. The results are shown in Table 1. [Example 4] An integrally molded article was produced in the same manner as in Example 1, except that the thermoplastic resin used for the fiber reinforced resin was polyamide 6 resin (A1030 manufactured by Unitika Ltd.). The results are shown in Table 1. [Comparative Example 1] A thin metal film (aluminum foil (manufactured by UACJ Foil Corporation) with a width of 20 cm and a thickness of 0.050 mm) was cut to 1000 mm without slitting and sandwiched as is between nonwoven fabrics of polypropylene resin to prepare a shielding layer precursor. An attempt was made to prepare an integrally molded body by cold pressing using this shielding layer precursor and the same fiber-reinforced resin as in Example 1, but the aluminum foil broke during molding, and it was not possible to prepare a shielding layer.

[0117] [Table 1]

Claims

1. An integrally molded body having a fiber reinforced resin layer containing reinforced fibers and a first matrix resin, and a shielding layer, the shielding layer is a layer including an assembly of metal strips and a second matrix resin, and shields at least one of an electric field and a magnetic field; The assembly of metal strips is an integrally molded body consisting of a plurality of metal strips distributed within the surface of the shielding layer.

2. The integrally molded body according to claim 1 , wherein the integrally molded body has a top surface portion and a vertical surface portion.

3. 3. The integrally molded body according to claim 1, having a portion that satisfies 2≦tx / ty, where tx is a thickness of the shielding layer and ty is a thickness of the metal strip.

4. The integrally molded body according to claim 1 or 2, wherein a mass ratio W(metal) of the aggregate of the metal strips in the shielding layer is 30% or more.

5. 3. The integrally molded body according to claim 1, wherein the metal strip has a width of 1 mm to 40 mm, a length of 1 mm to 100 mm, and a thickness of 100 μm or less.

6. The integrally molded body according to claim 1 or 2, wherein the reinforcing fibers are discontinuous fibers dispersed in the in-plane direction of the fiber-reinforced resin layer.

7. The integrally molded body according to claim 1 or 2, wherein the shielding layer has a shielding property against an electric or magnetic field of 10 decibels or more in at least a part of a region exceeding 0 MHz and not exceeding 3000 MHz.

8. The integrally molded body according to claim 1 or 2, wherein the shielding layer has a shielding property against an electric or magnetic field of 10 decibels or more in at least a part of a region exceeding 0 MHz and not exceeding 100 MHz.

9. 3. The integrally molded body according to claim 2, wherein a thickness ta of the vertical surface portion and a thickness tb of the top surface portion satisfy the relationship ta≦tb.

10. The thickness of the shielding layer at the vertical surface portion is txa, and the thickness of the fiber reinforced resin layer is ta-txa, When the thickness of the shielding layer on the top surface portion is txb and the thickness of the fiber reinforced resin layer is tb-txb, txa≦txb and ta−txa≧tb−txb are satisfied. The integrally molded body according to claim 9.

11. A vehicle structure having an integrally molded body as described in claim 1 or 2.

12. A component of a battery box having the integrally molded body according to claim 1 or 2, A component of the battery box located under the vehicle body.

13. A method for producing the integrally molded body described in claim 1 or 2, comprising stacking a fiber-reinforced resin containing reinforcing fibers and a first matrix resin with a shielding layer precursor, and press-molding the laminate using an upper molding die and a lower molding die.

14. The method for producing the integrally molded body according to claim 13, wherein the fiber reinforced resin and the shielding layer precursor are laminated together so that the fiber reinforced resin contacts the molding die, and then the laminate is placed in the molding die and press molded.

15. A method for manufacturing an integrally molded body as described in claim 13, wherein the relationship between the ductility E1 of the fiber-reinforced resin and the ductility E2 of the laminate of the fiber-reinforced resin and the shielding layer precursor is 0.9 < E1 / E2 < 50.

16. The method for producing a single-piece molded article according to claim 13, wherein the first matrix resin and the second matrix resin are thermoplastic resins.

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