Integrally molded body of fiber-reinforced resin layer and blocking 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

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

[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.

[0002] Many studies have been conducted on techniques for shielding electric fields using metal and resin. Patent Document 1 describes a resin molded product 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 on top of each other and set 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 areas where the electromagnetic wave shielding layer does not follow the components of a battery box that has a recess.

[0005] Patent Document 4 describes an electromagnetic wave shielding material in which at least two elastic layers made of resin elastic fibers and a shielding layer of granular or flake-shaped magnetic material sandwiched between them are integrally molded, thereby partially melting and solidifying the elastic fibers, entangling the magnetic material with the elastic fibers and holding it in a semi-floating state. In the electromagnetic wave shielding material described in Patent Document 4, each particle or flake 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. Patent Document 5 describes an electromagnetic wave shielding body that can be formed into a highly processed electromagnetic wave shielding body, such as a box-shaped one, by heat molding, and the conductive composition layer is not damaged during processing, thereby maintaining stable electromagnetic wave shielding performance. Patent Document 6 discloses an electromagnetic wave shielding composite material in which a fiber-reinforced resin molded body portion containing carbon fiber and a matrix resin and a metal layer portion are laminated.

[0006] Japanese Unexamined Patent Publication No. 58-84856 Japanese Unexamined Patent Publication No. 4-110278 International Publication No. 2021 / 125386 Japanese Unexamined Patent Application No. 09-292480 Unexamined Japanese Patent Application No. 06-021683 Unexamined Japanese Patent Application No. 2012-109454

[0007] Vehicle structures may require shielding properties to block radio waves and magnetic waves. However, the resin molded article containing foil-shaped metal flakes described in Patent Document 1 is simply made by mixing metal flakes into a resin molded article, which may result in poor shielding properties against radio waves or magnetic fields. In general, the higher the conductivity of a material, the higher the shielding properties against electric or magnetic fields. In the resin molded article containing foil-shaped 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. As a result, the conductivity of the resin molded article described in Patent Document 1 is not high, and the shielding properties against electric or magnetic fields are insufficient.

[0008] Although Patent Document 2 attempts to shape aluminum foil by adding 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 adapted to conform to the components of the battery box having recesses. No technology has been considered for making the shielding layer conform to recesses or deep-drawn portions. In order to install the shielding layer so that it conforms to a molded body having 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. Furthermore, only one of the two types of resin is melted and placed in a semi-floating state, so it is not fixed. In the electromagnetic wave shielding body described in Patent Document 5, metal fibers are used, which results in gaps. In the electromagnetic wave shielding composite material described in Patent Document 6, metal plates are used, so the metal plates cannot conform when integrally molded into a complex-shaped molded body.

[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 comprising a fiber-reinforced resin layer containing reinforcing fibers and a first matrix resin and a shielding layer, wherein the shielding layer is a layer containing an aggregate of metal strips and a second matrix resin, and shields at least one of electric and magnetic fields, and the aggregate of metal strips consists of a plurality of metal strips dispersed within the surface of the shielding layer. 2. The integrally molded body according to item 1 above, having a top surface portion and a vertical surface portion. 3. The integrally molded body according to any one of items 1 or 2 above, 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 above, wherein the mass proportion W(metal) of the aggregate of metal strips in the shielding layer is 30% or more. 5. The integrally molded body according to any one of items 1 to 4 above, 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. 6. The integrally molded body according to any one of items 1 to 5, wherein the reinforcing fibers are discontinuous fibers and dispersed in the in-plane direction of the fiber-reinforced resin layer. 7. The integrally molded body according to 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 part of a region exceeding 0 MHz and not more than 3000 MHz. 8. The integrally molded body according to 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 part of a region exceeding 0 MHz and not more than 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 ta≦tb. 10. 10. The integrally molded body according to claim 9, wherein, when the thickness of the shielding layer at the elevation portion is txa, the thickness of the fiber reinforced resin layer is ta-txa, the thickness of the shielding layer at 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. 11. A vehicle structure having the integrally molded body according to any one of claims 1 to 10. 12. A component of a battery box, having the integrally molded body according to any one of claims 1 to 10, the component of a battery box being arranged in a lower part of a vehicle body.13. A method for producing the integrally molded body according to any one of items 1 to 10, comprising 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. 14. A method for producing the integrally molded body according to item 13, comprising laminating the fiber-reinforced resin and the shielding layer precursor so that the fiber-reinforced resin is in contact with the lower molding die, and then placing the laminate in the lower molding die and press-molding. 15. A method for producing the integrally molded body according to any one of items 13 or 14, wherein the relationship between the malleability E1 of the fiber-reinforced resin and the malleability E2 of the laminate of the fiber-reinforced resin and the shielding layer precursor is 0.9 < E1 / E2 < 50. 16. A method for producing the integrally molded body according to any one of items 13 to 15, wherein the first matrix resin and the second matrix resin are thermoplastic resins.

[0013] By using an assembly of metal strips, it is possible to integrally mold it with a fiber-reinforced resin layer having a complex three-dimensional shape, simplifying the process of pre-shaping the metal shielding layer and adhering it to the fiber-reinforced resin layer.

[0014] 1 is a schematic cross-sectional view of an integrally molded body. A state in which a shape is formed using only a metal plate using a molding die. Before the upper die is closed. A state in which the upper die is closed and pressing the metal plate. A plan view showing an example of a shielding layer precursor 20. A photograph showing a state in which some metal strips are laid sideways. Evaluation of the electric field shielding performance of a 150 μm thick polypropylene resin layer. Evaluation of the electric field shielding performance of a 150 μm thick shielding layer containing an aluminum thin film and a polypropylene resin when the mass fraction W of the aluminum thin film is 25%. Evaluation of the electric field shielding performance of a 150 μm thick shielding layer containing an aluminum thin film and a polypropylene resin when the mass fraction W of the aluminum thin film is 45%. Evaluation of the electric field shielding performance of a 150 μm thick shielding layer containing an aluminum thin film and a polypropylene resin when the mass fraction W of the aluminum thin film is 65%. Evaluation of the electric field shielding performance of a 150 μm thick shielding layer containing an aluminum thin film and a polypropylene resin when the mass fraction W of the metal (aluminum) thin film is 75%. 11 is an evaluation of the electric field shielding performance of a 150 μm-thick aluminum thin film. A schematic diagram of slitting a metal strip by pressing it against a support roller. A schematic side view of slitting a metal strip using a shear blade method. A cross-sectional view taken along the arrows VIII-VIII of FIG. 7. An enlarged view of portion IX of FIG. 8. A schematic diagram of slitting a metal strip using a gang method. A cross-sectional view taken along the arrows XI-XI of FIG. 10. An enlarged view of portion XII of FIG. 11. A cross-sectional view showing an example of an integrally molded body 1A. An exploded perspective view showing an example of a battery box using an integrally molded body. A perspective view showing an example of a battery tray. A cross-sectional view taken along the arrows XVI-XVI of FIG. 15. A schematic diagram for explaining a method of measuring a molding heating temperature. A schematic diagram for explaining a method of measuring malleability. A schematic diagram for explaining a method of measuring malleability.

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

[0018] [Advantages of Using an Aggregate of Metal Strips During Molding] 1. Issues with the Prior Art When a metal sheet is molded separately from a fiber-reinforced resin layer without using an aggregate of metal strips, the unevenness of the molding die tends to cause tearing, especially at the corners. This is due to the fact that the metal sheet (e.g., aluminum foil) elongates 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 molding using only the metal sheet, it is necessary to provide a gentle curve at the corners of the molding die to prevent the metal sheet from being broken by the molding die. Another method to improve yield has been to reinforce the location shown as 1101 in Figure 2B by attaching a cushioning or reinforcing material such as packing tape to prevent tearing. Furthermore, when deep drawing is attempted on a metal sheet, not just at the corners as shown in Figure 2B, the area tends to wrinkle. Alternatively, the metal layer design needs to be designed to soften the sharpness of the corners.

[0019] 2. Effect of the Assembly of Metal Strips (i) On the other hand, when an assembly of metal strips is used for integral molding, the shielding layer precursor is less likely to break even when it hits the corners of the molding die, and there is no need to provide a soft curve to the corners of the molding die.

[0020] 3. Effect of the metal strip assembly (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 molding die and the fiber-reinforced resin is laminated so as to contact the upper molding die, the fiber-reinforced resin will not cool to the molding die temperature until just before it contacts the upper molding die. This makes it easier to impart ribs and bosses to the fiber-reinforced resin, improving its design.

[0021] 4. Effect of the assembly of metal strips (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 the metal strip assembly (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 end of the shielding layer is embedded in resin during integral molding, chipping at the end 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 it easy to slit. 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, even more preferably 50 μm or less, and even more preferably 30 μm or less. The lower limit of the metal strip thickness is preferably 12 μm or more, and more preferably 15 μm or more. The metal strip may also be in the form of a strip. The weight of each metal strip is preferably 0.001 g or more and 0.050 g or less, more preferably 0.003 g or more and 0.040 g or less, and even more preferably 0.005 g or more and 0.020 g or less. Specifically, for a metal strip having a width of 5 mm, a length of 20 mm, and a thickness of 30 μm, the weight is approximately 0.008 g. When such light metal strips are dispersed, some of the metal strips will stand upright rather than being laid down. Specifically, less than 1% of the metal thin film will stand upright (e.g., 901 in Figure 4). Here, "standing" metal strips refers to the thickness direction being oriented horizontally. Standing metal strips will be crushed during integral molding.

[0027] [Shielding layer: mass ratio W(metal) of aggregate of metal strips] The mass ratio 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 ratio 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, etc.

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

[0029] [Shielding Layer: Randomly Dispersed in In-Plane Direction] Figure 3 is a plan view showing an example of the shielding layer precursor 20. As shown in Figure 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 flowing, 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 dispersed randomly. "Randomly dispersed" refers to a state in which the metal strips are oriented randomly in 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 in the plane overall without showing a specific directionality. It should be noted that even if some of the metal strips are laid on their sides (with the thickness direction of the metal strips facing in the in-plane direction of the shielding layer) when preparing the assembly of metal strips (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 Field or Magnetic Field] 1. The shielding layer shields at least one of an electric field or a magnetic field, and preferably has an electric field or magnetic field shielding property of 10 decibels or more in at least a part of the range from more than 0 MHz to 3000 MHz or less. The electric field 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 shielded region, the electric or magnetic field shielding property is preferably 10 decibels 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 decibels or more, and even more preferably 30 decibels or more. "In at least 50% of the region from above 0 MHz to 3000 MHz" means that the shielded 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 more than 0 MHz to 3000 MHz or less, more preferably 20 dB or more, and even more preferably 30 dB or more.

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

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

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

[0036] The shielding performance will be explained using the graphs depicted in FIGS. 5A to 5F. FIG. 5A is a graph of the electric field shielding performance of a 150 μm-thick polypropylene resin layer. FIG. 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%. FIG. 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%. FIG. 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%. FIG. 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%. FIG. 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 than 100MHz (10 ８ 5B , an electric field shielding performance of approximately 20 dB is shown. In the region of 0.1 MHz to 100 MHz in FIG. 5C , an electric field shielding performance of approximately 33 dB is shown. In the region of 0.1 MHz to 100 MHz in FIG. 5D , an electric field shielding performance of approximately 35 to 50 dB is shown. In the region of 0.1 MHz to 100 MHz in FIG. 5E , an electric field shielding performance of approximately 35 to 76 dB is shown. In the region of 0.1 MHz to 100 MHz in FIG. 5F , an electric field shielding performance of approximately 35 to 122 dB is shown.

[0037] [Thickness of Shielding Layer] There is no particular limitation on the thickness tx of the shielding layer in the present invention, 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 more, 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 to 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 when 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 portion falls within the above range.

[0039] [Shielding layer: reinforcing fiber] Reinforcing fiber may be added to the shielding layer. This is to prevent the assembly of metal strips from breaking apart and draping down when the shielding layer is subjected to a combustion test. In addition, the presence of reinforcing fiber in the shielding layer improves ductility. Aramid fiber, glass fiber, or carbon fiber is preferred as the reinforcing fiber mixed into the shielding layer.

[0040] [Shielding layer: manufacturing method of shielding layer precursor] The integrally molded body of the present invention is preferably manufactured 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 manufacturing method of the shielding layer precursor, but it can be manufactured as follows.

[0041] 1. Preparation of Metal Strip Assembly 1.1 Slitting Metal strip assembly can be produced by slitting a wide metal thin film and then cutting it. 1.1.1 Roller Press Slitting (Figure 6) Figure 6 shows a schematic diagram of a thin metal strip 501 produced by pressing a metal thin film against a support roller (rubber roller 503) shown in Figure 6 and slitting it with a blade 502. As shown in Figure 6, the metal thin film is pressed against a high-hardness rubber roller 503 that has been heat-treated, such as quenched, and slit. In this case, adjustments must be made to prevent scratches on the rubber roller 503, which could cause the metal thin film to become pinched.

[0042] 1.1.2 Slitting with a Shear Blade (FIGS. 7 to 9) Figures 7 to 9 are schematic diagrams showing how a metal thin film 603 is slit using a shear blade. Figure 7 is a side view showing the state in which the metal thin film 603 is passed between the upper rotary blade 601 and the lower rotary blade 602, Figure 8 is a cross-sectional view taken along line VIII-VIII in Figure 7, and Figure 9 is an enlarged view of part IX in Figure 8. As shown in Figures 7 to 9, the upper rotary blade 601 is equipped 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 Method (Figures 10-12) Figures 10-12 show schematic diagrams of separating a reinforcing fiber bundle using the gang method. Figure 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. Figure 11 is a cross-sectional view taken along line XI-XI in Figure 10. Figure 12 is an enlarged view of section XII in Figure 11. As shown in Figures 10-12, 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 the tips of the blades overlap, leaving 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 fiber. As with the shear blade method, high-precision clearance management is required over time.

[0044] 1.2 Cutting of Slit Metal Strip The slit metal strip is cut to a fixed length using, for example, a rotary cutter, and then spread and fixed on a resin previously prepared on an air-permeable support that moves continuously in one direction and has a suction mechanism underneath, which is 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, a resin 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 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, a sheet molding compound (sometimes called SMC) containing reinforcing fibers may be used as the fiber-reinforced resin. Sheet molding compounds have high moldability, making them easy to mold into even complex shapes. Compared to continuous fibers, sheet molding compounds have higher fluidity and formability, making it easy to create ribs and bosses.

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

[0052] In this embodiment, the assembly of metal strips is sandwiched and welded using polypropylene resin. One sheet of the prepared shielding layer precursor 20 may be used for integral molding with the fiber reinforced resin 10, or two or more sheets of the shielding layer precursor 20 may be stacked or may be used separately without being stacked for integral molding with the fiber reinforced resin 10.

[0053] [Shielding layer: ductility] Ductility refers to the degree to which a material can deform in response to an external force and continue to stretch without breaking. Generally, it refers to the property of a material being stretched as it deforms when an external force is applied to it, and as this deformation continues. For example, metals have high ductility and can be stretched into long, thin pieces when pulled. This property is used to process metal products and to manufacture wire, etc. On the other hand, brittle materials such as glass and ceramics have low ductility and tend to break easily when external forces are applied. In general, the formability of metals is inferior to that of resins.

[0054] In the integrally 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, even 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 plate-shaped, and that the shielding layer precursor is flowed in the in-plane direction of the fiber-reinforced resin to stretch the surface, thereby producing a press-molded body. Also, in the present invention, it is preferable that the ductility of the fiber-reinforced resin is more than 1% and not more than 300%, and more preferably more than 20% and not more than 150%.

[0056] The ductility of the laminate of the fiber-reinforced resin and the shielding layer precursor is preferably more than 2% and not more than 100%, and more preferably more than 10% and less than 80%. Mixing reinforcing fibers into the shielding layer precursor improves the ductility. It is also preferable that E1 > E2. When the values ​​of E1 and E2 are close, it is easy to form an integrally molded body. The method for measuring ductility will be described later. Note that ductility is sometimes called the ductility rate and is expressed as a percentage.

[0057] [Shielding Layer: Comparison with Continuous Fiber Net] One idea for making a shielding layer conform to a 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 integrated 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 widening of the gaps), 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: reinforcing 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 using carbon fiber, generally known types include polyacrylonitrile (PAN)-based carbon fiber, petroleum / coal pitch-based carbon fiber, rayon-based carbon fiber, cellulose-based carbon fiber, lignin-based carbon fiber, and phenol-based carbon fiber. Any of these carbon fibers can be suitably used in the present invention. Among these, polyacrylonitrile (PAN)-based carbon fiber is preferably used in the present invention because of its excellent tensile strength. As a PAN-based carbon fiber, for example, TENAX (registered trademark) STS40-24KS carbon fiber (average fiber diameter 7 μm) manufactured by Teijin Limited can be used.

[0060] 2. Sizing Agent for Carbon Fiber 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. General glass fiber The glass fiber used in the present invention may be any glass fiber that is generally called glass fiber. There is no particular limitation on the glass composition such as A-glass, C-glass, E-glass, etc., and in some cases, TiO ２ , S.O. ３ , P ２ O ５ The glass fiber may contain components such as E-glass RS240QR-483 (count: 2400 g / 1000 m) manufactured by Nitto Boseki Co., Ltd., for example.

[0062] 2. Sizing Agent for Glass Fiber 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: reinforcing 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. Randomly dispersed in two dimensions It is preferable that the reinforcing fibers are randomly dispersed in two dimensions in the in-plane direction. In the region where the fiber-reinforced resin is press-molded without flow, 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 two dimensions in the in-plane direction.

[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 directions perpendicular to each other. If the (Eδ) ratio, obtained by dividing the larger of the tensile modulus values ​​measured in any direction of the fiber reinforced resin or fiber reinforced resin layer and the direction perpendicular thereto, by the smaller, is 5 or less, more preferably 2 or less, and even more preferably 1.5 or less, it can be evaluated that the reinforcing fibers are dispersed two-dimensionally randomly.

[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, the two-dimensional random dispersion in the in-plane direction can be evaluated by heating the fiber-reinforced resin layer above its softening temperature to return it to a flat plate shape and then solidifying it. Then, by cutting out a test piece and measuring the tensile modulus, the state of random dispersion in the two-dimensional direction can be confirmed.

[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 using 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, 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 it in the desired shape. Furthermore, if the weight average fiber length Lw is 1 mm or more, the mechanical strength of the obtained 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 using the following formulas (1) and (2). In a fiber-reinforced resin layer prepared by injection molding, the weight average fiber length of the reinforcing fibers is approximately 0.1 to 0.3 mm. Therefore, when the weight average fiber length of the reinforcing fibers is 1 mm or more and 100 mm or less, it is preferable to prepare 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, when 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 number-average fiber length Ln and weight-average fiber length Lw are expressed in mm. Here, "I" indicates the number of reinforcing fibers measured.

[0074] When the fiber length is constant, the number average fiber length and the weight average fiber length are the same value. The 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 it based on Equation (1) or (2). If short fibers that cannot be measured with a vernier caliper are included, the resin is removed, and the resulting reinforcing fibers are placed in water containing a surfactant and thoroughly stirred using ultrasonic vibrations. The stirred dispersion is randomly sampled with a measuring spoon to obtain an evaluation sample, and the lengths of 3,000 fibers are measured using a Luzex AP image analyzer manufactured by Nireco Corporation. Using the measured fiber length values, the number average fiber length Ln and weight average fiber length Lw can be calculated in the same manner as in Equations (1) and (2) above.

[0076] [Fiber reinforced resin layer: fiber volume ratio of reinforcing fibers] The fiber volume ratio Vf of the reinforcing fibers is not particularly limited, but is preferably 20 to 70%, more preferably 25 to 60%, and even more preferably 30 to 55%. The fiber volume ratio (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 are no limitations on the analysis of the reinforcing fiber volume fraction, it is recommended to measure it as follows. A sample is cut out 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 before and after treatment is weighed to calculate the mass of the reinforcing fiber, resin, and other additives. Next, the volume fraction of the reinforcing fiber and 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 above-mentioned 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 only one type, or may be two or more types. Examples of the use of two or more 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. As the resin, one type may be used alone, or two or more types may be used in combination.

[0082] Alternatively, a sheet molding compound (sometimes called SMC) containing reinforcing fibers may be used as the fiber-reinforced resin. Sheet molding compounds have high moldability, making them easy to mold into even complex shapes. Compared to continuous fibers, 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, release agents, pigments, softeners, plasticizers, surfactants, etc., as long as the object of the present invention is not impaired. When a thermosetting resin is used, it may contain a thickener, a curing agent, a polymerization initiator, a polymerization inhibitor, etc. As the additive, one type may be used alone, or two or more types may be used in combination.

[0084] [Thermoplastic Resin 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, from the viewpoint that the shielding layer precursor needs to be molded in accordance with 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 a fiber-reinforced resin layer containing reinforcing fibers and a first matrix resin, and a shielding layer. Here, integral molding refers to a body that is molded continuously without any seams and is not formed by joining separate components together. Such integral molding is achieved by creating a body in a single molding operation, preferably by press molding. Because it is created 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 manufactured 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 placed one on top of the other, and pressed simultaneously in a molding die to manufacture an integrally molded body.

[0087] 1. Fiber-reinforced resin and shielding layer precursor There are no particular limitations on the method for overlapping the fiber-reinforced resin and the shielding layer precursor, but because the shielding layer precursor has high conformability to the fiber-reinforced resin, it is preferable to overlap them in pieces of the same size. There are no particular limitations on the volume ratio of the fiber-reinforced resin Vx to the shielding layer precursor Vy, but 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 from the melting point to the decomposition temperature if the thermoplastic resin is crystalline, or from the glass transition temperature to the decomposition temperature if the thermoplastic resin is amorphous. Step A-2) A step of placing the fiber-reinforced resin and the shielding layer precursor heated in step A-1) 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 applying pressure. 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 above order, but other steps may be included between each step. Examples of other steps include a shaping step, prior to step A-2), in which a shaping mold different from the mold used in step A-2) is used to pre-shape the material 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-generated inverse molding analysis from the three-dimensional shape of the press-molded body to be manufactured.

[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 step of applying pressure while heating the molding die (first pressing step) 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. B-3) A step 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 step (second pressing step). B-4) A step of adjusting the molding die 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 performing 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, it 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 machine. Naturally, various processes may be inserted between the above-mentioned steps during compression molding; for example, vacuum compression molding, in which compression molding is performed under vacuum, may be used.

[0095] 4. Arrangement (stacking order) of fiber-reinforced resin and shielding layer precursor 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 contacts 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 contacts 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 contacts 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 manufactured 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 state of the 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. Once the resin has spread, it is preferable to heat the mold to promote curing of the epoxy resin. Even with this method, an integrally molded article can be produced in which a fiber-reinforced resin layer containing the reinforcing fibers and the first matrix resin of the present invention and a shielding layer are integrally molded.

[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. This is 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, by setting the mold temperature for RTM molding higher than the softening temperature of the second matrix resin to harden the first matrix resin and then providing a step of lowering the mold temperature to below the softening temperature of the second matrix resin, the fiber-reinforced resin layer and the shielding layer can be demolded in a solidified state. In recent years, progress has been made in the development of resins with fast hardening rates, and RTM molding is contributing to the mass production of large composite products.

[0098] [Shape of the integrally molded body] The integrally molded body 1A has a flat portion and a vertical portion. Specifically, it preferably has at least one flat portion 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 (e.g., ribs, bosses, etc.).

[0099] Fig. 13 is a cross-sectional view showing an example of an integrally molded body 1A according to 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 produced according to the present invention preferably has a cross-sectional shape including a hat-shaped portion having a top surface portion 50 and a vertical surface portion 60. The top surface portion 50 is an example of a flat portion. For example, a side door, a back door, or a roof for an automobile may also have the vertical surface portion and the top surface portion of the present invention.

[0100] The thickness ta of the vertical surface portion of the integrally molded body 1A and the thickness tb of the top surface portion preferably satisfy the relationship ta≦tb. It is more preferable that ta×0.8<tb, and even more preferable that ta×0.6<tb. For example, when a plate-shaped shielding layer precursor 20 and fiber-reinforced resin 10 are used, the thickness of the laminate 1 of the shielding layer precursor 20 and fiber-reinforced resin 10 is uniform. When this is used to create a hat-shaped integrally molded body, the vertical surface portion tends to be stretched by the molding die and become thinner than the top surface portion.

[0101] On the other hand, in the integrally molded body 1A of the present invention, when the thickness ta of the vertical surface portion 60 and the thickness tb of the top surface portion 50 are made the same thickness, it is preferable to satisfy txa≦txb and ta−txa≧tb−txb, where txa is the thickness of the shielding layer 20A in the vertical surface portion 60, ta−txa is the thickness of the fiber reinforced resin layer 10A, txb is the thickness of the shielding layer 20A in the top surface portion 50, and tb−txb is the thickness of the fiber reinforced resin layer 10A. In other words, since the fiber reinforced resin 10 has greater ductility than the shielding layer precursor 20, the thickness of the vertical surface portion 60 can be easily increased during molding.

[0102] [Integrated Body: Battery Tray and Battery Cover] The integrated body is preferably a vehicle structure. The vehicle structure is preferably a component of a battery box, and the component of the battery box is preferably disposed under the vehicle body. FIG. 14 is an exploded perspective view of a battery box 101 using the integrated 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 integrated 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 used to drive an automobile and is used to mount the battery 103 for driving the vehicle.

[0104] Figure 15 is a perspective view of the battery tray 105, and Figure 16 is a cross-sectional view taken along the line XVI-XVI in Figure 15. As shown in Figures 15 and 16, the battery tray 105 includes a first bottom portion 303 and a peripheral wall 203 erected on the outer periphery of the first bottom portion 303. The battery tray 105 also includes a first inner wall 204 connected to the first bottom portion 303, a second inner wall 205 connected to the first bottom portion 303, and a second bottom portion 301 connected to both the first inner wall 204 and the second inner wall 205 and raised from the first bottom portion. The first bottom portion 303, the peripheral wall 203, the first inner wall 204, the second inner wall 205, and the second bottom 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 shield electromagnetic waves radiated from the battery 103 and prevent them from radiating or leaking to the outside, ensuring sufficient electromagnetic wave shielding properties for the battery box and making it possible to suppress, for example, adverse effects of electromagnetic waves on the vehicle control system and the human body.

[0106] [Shielding Layer: Conforming to Concave Parts] For example, the battery boxes depicted in Figures 15 and 16 have complex shapes, and have large concave parts such as those indicated by 313 in Figure 15. How to cover these concave parts with a shielding layer is an issue, but by using the shielding layer precursor of the present invention, it becomes easy to make the shielding layer conform to the shape of these concave parts.

[0107] 2. Evaluation 2.1 Shielding Properties A 150mm x 150mm test piece (flat plate) was sampled from the integrally molded body and the radio wave shielding properties for electric field waves (frequency 0 MHz to 100 MHz) were 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 properties. Good: In the entire range from 0 MHz to 100 MHz, the electrolytic shielding properties are 40 dB or more. Bad: In the entire range from 0 MHz to 100 MHz, the electrolytic shielding properties are 5 dB or less.

[0108] 2.2 Measurement of the ductility of the laminate of the shielding layer precursor and the fiber-reinforced resin 2.2.1 Measurement of the molding heating temperature (1) Prepare a fiber-reinforced resin (or a laminate of the shielding layer precursor and the fiber-reinforced resin) cut to 200 mm x 200 mm. (2) As shown in Figure 17A, a 100 mm x 200 mm area, which is half of the fiber-reinforced resin 1001 (or the laminate of the shielding layer precursor and the fiber-reinforced resin), is placed on a wire mesh 1002. The wire mesh 1002 is placed on a 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 the shielding layer precursor and the fiber-reinforced resin) decreases and the fiber-reinforced resin (or the laminate of the shielding layer precursor and the fiber-reinforced resin) sags 10 mm from the original height under its own weight is measured. This temperature is the softening temperature. The subsequent molding heating temperature is set to 50°C above this temperature.

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

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

[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 A nonwoven fabric of polypropylene resin (Novatec (registered trademark) PPBC03C manufactured by Japan Polypropylene Corporation) was prepared as the thermoplastic resin for the first layer. Next, as the thin metal film, a 20 cm wide, 0.012 mm thick aluminum foil (manufactured by UACJ Foil Co., Ltd.) was slit using a rotary slit with a 3 mm pitch and further 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 metal strips were then spread and fixed on a thermoplastic resin nonwoven fabric (the thermoplastic resin for the first layer) previously prepared on an air-permeable support that was placed directly below the rotary cutter and moved continuously in one direction, thereby obtaining 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, providing a second layer of thermoplastic resin, thereby obtaining 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. Nitto Boseki's E-glass RS240QR-483 glass fiber was used as the glass fiber, and a sizing agent was applied to it before cutting it to a fiber length of 20 mm. The thermoplastic resin used was a 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 U.S. Patent No. 8,946,342, a composite composition of glass fiber and polypropylene resin with two-dimensionally randomly oriented glass fibers was prepared. Specifically, a breathable support with a suction mechanism attached to the bottom was installed, and while suction was being performed by the suction mechanism, the glass fiber and polypropylene resin were blown onto the top of the breathable support with compressed air from a tapered tube positioned above the breathable support, creating a composite product in which the glass fiber and polypropylene resin were mixed. The resulting composite composition was heated at 2.0 MPa for 5 minutes in a press heated to 250°C to create a fiber-reinforced resin measuring 600 mm x 1000 mm with an average thickness of 3 mm. The properties of the shielding layer precursor and the 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 pressure was applied for one minute at a pressure of 20 MPa (the time from the start of pressure application to reaching 20 MPa was 1 second), simultaneously pressing the fiber-reinforced resin and the shielding layer precursor together to produce an integrally molded body having a top surface, a vertical surface, and corners formed by connecting the top surface and the vertical surface. The results are shown in Table 1.

[0116] [Example 2] An integrally molded body was produced in the same manner as in Example 1, except that three sheets of the prepared shielding layer precursor were used. 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 at a mass ratio of 10%. The results are shown in Table 1. [Example 4] An integrally molded body was produced in the same manner as in Example 1, except that polyamide 6 resin (A1030 manufactured by Unitika Ltd.) was used as the thermoplastic resin for the fiber-reinforced resin. The results are shown in Table 1. [Comparative Example 1] A thin metal film (aluminum foil (manufactured by UACJ Foil) 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 polypropylene resin nonwoven fabrics to produce a shielding layer precursor. An attempt was made to produce 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 a shielding layer could not be produced.

[0117]

Claims

1. A one-piece molded body having a fiber-reinforced resin layer containing reinforcing fibers and a first matrix resin, and a shielding layer, wherein the shielding layer is a layer containing an aggregate of metal strips and a second matrix resin, and shields at least one of an electric field or a magnetic field, and the aggregate of metal strips is composed of a plurality of metal strips dispersed in the plane of the shielding layer. A one-piece molded body.

2. The one-piece molded body according to claim 1, wherein the one-piece molded body has a top surface portion and a standing surface portion.

3. The one-piece molded body according to claim 1 or 2, having a portion satisfying 2 ≤ tx / ty, where tx is the thickness of the shielding layer and ty is the thickness of the metal strip.

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

5. The one-piece molded body according to claim 1 or 2, wherein the metal strip has a width of 1 mm or more and 40 mm or less, a length of 1 mm or more and 100 mm or less, and a thickness of 100 μm or less.

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

7. The one-piece molded body according to claim 1 or 2, wherein the shielding layer has a shielding property of 10 decibels or more for at least a part of a region of more than 0 MHz and 3000 MHz or less for an electric field or a magnetic field.

8. The one-piece molded body according to claim 1 or 2, wherein the shielding layer has a shielding property of 10 decibels or more for at least a part of a region of more than 0 MHz and 100 MHz or less for an electric field or a magnetic field.

9. The one-piece molded body according to claim 2, wherein the thickness ta of the standing surface portion and the thickness tb of the top surface portion satisfy ta ≤ tb.

10. Let the thickness of the shielding layer in the standing surface portion be txa, and the thickness of the fiber-reinforced resin layer be ta - txa, and when 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, satisfying txa ≤ txb and ta - txa ≥ tb - txb, The one-piece molded body according to claim 9.

11. A vehicle structure having the one-piece molded body according to claim 1 or 2.

12. A component of a battery box having the one-piece molded body according to claim 1 or 2, wherein the component of the battery box is disposed below the vehicle body.

13. A method for manufacturing the integrally molded body according to claim 1 or 2, 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. The method for manufacturing the integrally molded body according to claim 13, wherein the fiber-reinforced resin and the shielding layer precursor are laminated so that the fiber-reinforced resin contacts the lower molding die, and are placed on the lower molding die and press-molded.

15. The method for manufacturing the integrally molded body according to claim 13, 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. The method for manufacturing the integrally molded body according to claim 13, wherein the first matrix resin and the second matrix resin are thermoplastic resins.