Fiber-reinforced resin material for car body

Abstract

A fiber-reinforced resin material (M) for a car body comprises: a plurality of first reinforcing fiber layers (1) formed of unopened reinforcing fiber bundles; a second reinforcing fiber layer group (2) in which a plurality of second reinforcing fiber layers (2a) formed of opened reinforcing fiber bundles are continuously laminated; and a matrix resin impregnating the first reinforcing fiber layers (1) and the second reinforcing fiber layers (2a), and being reinforced by the first reinforcing fiber layers (1) and the second reinforcing fiber layers (2a). When a load is generated in an in-plane direction by an external force (F) to form a bent in the fiber-reinforced resin material (M) and a compressive or a tensile force acts on the fiber-reinforced resin material (M), the region inward of the bent is defined as a compression-side region (CR) on which a compressive stress acts and the region outward of the bent is defined as a tensile-side region (TR) on which a tensile stress acts, with respect to a thickness central plane (CP) of the fiber-reinforced resin material (M). The second reinforcing fiber layer group (2) is located in the tensile-side region (TR).

Description

Fiber-reinforced plastic materials for car bodies

[0001] The present invention relates to a fiber reinforced plastic member for a vehicle body.

[0002] Patent Document 1 below discloses a carbon fiber reinforced resin material. In the carbon fiber reinforced resin material disclosed in Patent Document 1, multiple thin carbon fiber layers formed by tow spreading are laminated within a matrix resin. The carbon fiber bundles used in carbon fiber reinforced resins are composed of a large number of filaments and typically have a circular or elliptical cross section. The fiber bundles are also called tows, and carbon fiber tows often use carbon fiber filaments with a diameter of 4 to 7 μm.

[0003] Tows are classified by the number of filaments, such as 12k and 24k. A 12k tow is composed of 12,000 filaments. A relatively thin tow of 24k or less is typically called a regular tow, while a thick tow of 40k or more is called a large tow. Spread tow technology is a technique for spreading the tow filaments thinly and uniformly, and large tow is typically used. Molding a carbon fiber reinforced resin material by stacking multiple thin carbon fiber layers formed using spread tow can improve the mechanical properties of the carbon fiber reinforced resin material, such as its strength and elastic modulus (hardness), as described in Patent Document 1.

[0004] Japanese Patent Publication No. 2014-208457

[0005] However, since the thickness of each carbon fiber layer is reduced, the number of carbon fiber layers stacked in the carbon fiber reinforced resin material increases, which increases the number of stacking steps and makes it difficult to improve productivity.

[0006] An object of the present invention is to provide a fiber-reinforced plastic material for vehicle bodies that can improve productivity while also improving mechanical properties.

[0007] A fiber-reinforced resin material for a vehicle body according to a first aspect of the present invention includes a second reinforcing fiber layer group in which a plurality of first reinforcing fiber layers formed from unspread reinforcing fiber bundles and a plurality of second reinforcing fiber layers formed from spread reinforcing fiber bundles are continuously laminated, and a matrix resin that impregnates the first reinforcing fiber layers and the second reinforcing fiber layers and is reinforced by the first reinforcing fiber layers and the second reinforcing fiber layers. When an external force that bends the fiber-reinforced resin material generates a load in the in-plane direction and a compressive force or a tensile force acts on the fiber-reinforced resin material, a region on the inside of the bend with respect to the center plane of the thickness of the fiber-reinforced resin material is a compression-side region in which compressive stress acts, and a region on the outside of the bend is a tension-side region in which tensile stress acts. The second reinforcing fiber layer group is arranged in the tension-side region.

[0008] A fiber-reinforced resin material for a vehicle body according to a second aspect of the present invention includes a plurality of first reinforcing fiber layers formed from unspread reinforcing fiber bundles, a second reinforcing fiber layer group in which a plurality of second reinforcing fiber layers formed from spread reinforcing fiber bundles are continuously laminated, and a matrix resin that impregnates the first reinforcing fiber layers and the second reinforcing fiber layers and is reinforced by the first reinforcing fiber layers and the second reinforcing fiber layers. When an external force that bends the fiber-reinforced resin material generates a load in the in-plane direction and a compressive force or a tensile force acts on the fiber-reinforced resin material, a region on the inside of the bend with respect to the center plane of the thickness of the fiber-reinforced resin material is a compression-side region where compressive stress acts, and a region on the outside of the bend is a tension-side region where tensile stress acts. The second reinforcing fiber layer group is arranged in the compression-side region.

[0009] According to the first feature, the number of layers of the thin second reinforcing fiber layers can be reduced to improve productivity, while the strength of the fiber-reinforced resin material can be improved by the second reinforcing fiber layer group.

[0010] According to the second feature, the number of layers of the thin second reinforcing fiber layers can be reduced to improve productivity, while the hardness of the fiber-reinforced resin material can be improved by the second reinforcing fiber layer group.

[0011] Fig. 1 is a schematic perspective view for explaining fiber spreading. Fig. 2 is a partial cross-sectional view of a fiber reinforced resin material for explaining the tension / compression side region. Fig. 3 is a schematic partial cross-sectional view of a fiber reinforced resin material according to a first embodiment. Fig. 4 is a schematic partial cross-sectional view of a fiber reinforced resin material according to a second embodiment. Fig. 5 is a schematic partial cross-sectional view of a fiber reinforced resin material according to a third embodiment.

[0012] First, "spreading" will be explained with reference to FIG. 1. Spreading is a technique for long-fiber reinforcing fibers and is not used for short-fiber reinforcing fibers. Unspread long-fiber reinforcing fibers are in the form of a fiber bundle 11, i.e., a tow 11, in which numerous filaments 10 are bundled together, as shown on the left side of FIG. 1. The tow 11 contains thousands to tens of thousands of filaments. Note that FIG. 1 is a schematic diagram, and the number of filaments 10 is not accurate. The cross section of an unspread tow 11 is circular or elliptical. Spreading is a technique for flattening this tow 11 to form a tow 12, as shown on the right side of FIG. 1, and there are various spreading methods. Spread tows 12 may be arranged in parallel to form a unidirectional (UD) reinforcing fiber layer, or spread tows 12 may be woven to form a quasi-isotropic reinforcing fiber layer. Pseudo-isotropy can also be achieved by stacking multiple tows 12 with the unidirectional directions crossed.

[0013] Whether or not the reinforcing fiber layer in the molded fiber-reinforced resin material is formed from opened fiber bundles (tows) can be determined by observing the thickness of the reinforcing fiber layer and the uniformity of the distribution of filaments within the reinforcing fiber layer.

[0014] The thickness of the reinforced fiber layer formed by the spread tows 12 is reduced. This allows the matrix resin to be sufficiently impregnated into the reinforced fiber layer. As a result, resin peeling within the reinforced fiber layer can be suppressed. Furthermore, while gaps tend to form when tows 11 with circular cross sections are arranged side by side, stacking flat tows 12 can also improve the fiber volume content Vf [%] of the reinforcing fibers. As a result, the mechanical properties of the fiber-reinforced resin can be improved. Therefore, fiber-reinforced resins using spread tows 12 exhibit improved mechanical properties. However, as described above, forming a fiber-reinforced resin material using only spread tows 12 requires a greater number of layers than a reinforcing fiber layer formed by unspread tows 11.

[0015] There are various methods for molding fiber-reinforced resin materials, such as a method using a prepreg made of a thermosetting resin and an RTM method using a thermoplastic resin. In the method using a prepreg, a large number of layers are required when stacking thin prepregs made of spread tows 12 on a shaping mold. The RTM method also requires a large number of layers when stacking and setting the spread tows 12 in a mold. This requires a long time for the stacking process, making it difficult to improve productivity. In the embodiment described below, productivity is improved by using both a reinforcing fiber layer made of spread tows 12 and a reinforcing fiber layer made of unspread tows 11, while optimizing the arrangement of the reinforcing fiber layer made of spread tows 12.

[0016] Next, prior to describing the following embodiments, the terms "tension-side region" and "compression-side region" will be explained with reference to FIG. 2 . FIG. 2 shows a typical fiber-reinforced resin material 100. An external force F that bends the fiber-reinforced resin material 100 generates a load in the in-plane direction, causing a compressive force or a tensile force to act on the fiber-reinforced resin material 100. In the example shown in FIG. 2 , the external force F acts in the thickness direction of the fiber-reinforced resin material 100, i.e., in the stacking direction of the reinforcing fiber layers 101. Note that, like FIG. 1 , FIG. 2 also schematically shows a cross section of the fiber-reinforced resin material 100. In FIG. 2 , the reinforcing fibers in each reinforcing fiber layer 101 are not explicitly shown, and only the state in which each reinforcing fiber layer 101 is impregnated with a matrix resin is shown. Furthermore, the matrix resins of each reinforcing fiber layer 101 are actually continuous with each other without forming a clear boundary. For example, when prepregs impregnated with matrix resin are laminated onto reinforcing fiber layers and then heated to harden the matrix resin, the thermosetting matrix resin first softens (liquefies) and then hardens as the curing reaction progresses. During this process, the clear boundaries between the matrix resins of the prepregs disappear, and the matrix resins become integrated. The schematic representations shown in Figures 1 and 2 are also used in Figures 3 to 5, which will be described later.

[0017] As shown in FIG. 2 , when an external force F bending the fiber-reinforced resin material 100 generates a load in the in-plane direction, causing a compressive or tensile force to act on the fiber-reinforced resin material 100, compressive stress acts on the inner side of the bend (bending concave side) within the fiber-reinforced resin material 100, and tensile stress acts on the outer side of the bend (bending convex side). Here, with respect to the center plane CP of the thickness of the fiber-reinforced resin material 100, the region on the inner side of the bend of the fiber-reinforced resin material 100 where compressive stress acts is defined as a compression-side region CR. Similarly, the region on the outer side of the bend of the fiber-reinforced resin material 100 where tensile stress acts is defined as a tension-side region TR. Hereinafter, first to third embodiments of the present invention will be described with reference to FIGS. 3 to 5 , and the terms "tension-side region TR" and "compression-side region CR" will be used as defined herein.

[0018] The fiber-reinforced resin material M according to the first to third embodiments shown in FIGS. 3 to 5 and described below is used for a vehicle body. Examples of the fiber-reinforced resin material M for a vehicle body include a vehicle body frame structural material and a vehicle body panel material. The vehicle body frame structural material is a member that receives a collision load during a vehicle collision. More specifically, examples of the vehicle body frame structural material include front and rear side members, side sills, A / B / C pillars, and roof side rails. Furthermore, more specifically, examples of the vehicle body panel material include a bonnet / hood that covers the engine / motor compartment at the front of the vehicle body, a trunk lid / hood that covers the trunk compartment at the rear of the vehicle body, front and rear fenders, door panels, and loop panels.

[0019] Vehicle body frame structural members are components that receive collision loads during a vehicle collision. When fiber-reinforced resin material M is used as a side member, the side member buckles to absorb collision energy during a frontal or rear collision. The buckling mode of the side member is controlled by its reinforcement material and beads formed on the side member. That is, the position of the fiber-reinforced resin material M in the side member determines how an external force F that bends the fiber-reinforced resin material M during a collision. Therefore, the "tension side region TR" and "compression side region CR" of the fiber-reinforced resin material M when an external force F that bends the fiber-reinforced resin material M is applied are known. When the fiber-reinforced resin material M is used as a side sill or B-pillar, the side sill or B-pillar secures the passenger compartment, i.e., survival space, during a side collision. That is, considering the external force F during a side collision, the passenger compartment side of the fiber-reinforced resin material M becomes the "tension side region TR." When the fiber reinforced resin material M is used for an A / C pillar or a roof rail, the A / C pillar or the roof rail secures the passenger compartment, i.e., the survival space, in the event of a vehicle rollover. In other words, when the external force F at the time of a vehicle rollover is taken into consideration, it can be seen that the passenger compartment side of the fiber reinforced resin material M becomes the "tensile side region TR."

[0020] Body panel materials are components that primarily form the outer panels of a vehicle. When fiber-reinforced resin material M is used as a body panel material, an external force F acts from outside the vehicle. Luggage may be placed on the bonnet / hood or roof, or a person may lean on the fender or door panel. Therefore, when fiber-reinforced resin material M is used as a body panel material, it can be seen that the outer surface side of the body panel material where the external force F acts becomes the "compression side region CR." If the body panel material is easily bent, the sense of quality is impaired.

[0021] As shown in Fig. 3, the fiber-reinforced resin material M of the first embodiment includes a plurality of first reinforcing fiber layers 1, a second reinforcing fiber layer group 2 in which a plurality of second reinforcing fiber layers 2a are continuously laminated, and a matrix resin. Each first reinforcing fiber layer 1 is formed of unspread reinforcing fiber bundles (tows). Each second reinforcing fiber layer 2a is formed of spread reinforcing fiber bundles (tows). The matrix resin impregnates the first reinforcing fiber layer 1 and the second reinforcing fiber layer 2a, and is reinforced by the first reinforcing fiber layer 1 and the second reinforcing fiber layer 2a.

[0022] Each of the first reinforcing fiber layer 1 and the second reinforcing fiber layer 2a may have unidirectional properties with tows arranged in parallel, or may be woven to have quasi-isotropy. Furthermore, since these fiber layers are laminated, quasi-isotropy can also be achieved by crossing the directionality of the stratum corneum. The reinforcing fiber in this embodiment is carbon fiber. The second reinforcing fiber layer group 2 is formed by continuously laminating second reinforcing fiber layers 2a formed from opened tows. Therefore, as described above, the second reinforcing fiber layer group 2 has good mechanical properties.

[0023] The second reinforcing fiber layer group 2 is disposed in the tension-side region TR. Reinforced fibers, particularly carbon fiber reinforced plastic (CFRP) reinforced with the carbon fibers used in this embodiment, can effectively resist tensile forces. Therefore, by disposing the second reinforcing fiber layer group 2 in the tension-side region TR, the bending strength of the fiber-reinforced resin material M can be improved. For example, since strength is required for the above-mentioned vehicle body frame structural material, the fiber-reinforced resin material M of this embodiment can be used as a vehicle body frame structural material.

[0024] Although it is possible to form the fiber-reinforced resin material M using only a large number of second reinforcing fiber layers 2a, as described above, the number of layers increases, making it difficult to improve productivity. As in the present embodiment, by using the second reinforcing fiber layer group 2 only in a portion and using the first reinforcing fiber layer 1 in the remaining portion, it is possible to minimize the increase in the number of layers and improve productivity, while also improving the strength of the fiber-reinforced resin material M with the second reinforcing fiber layer group 2. Furthermore, because the second reinforcing fiber layer group 2, which has a high fiber volume fraction Vf of carbon fiber, is only used in a portion, it is possible to minimize the increase in the amount of expensive carbon fiber used and suppress an increase in the production cost of the fiber-reinforced resin material M.

[0025] In particular, in this embodiment, the second reinforcing fiber layer group 2 is used as the outermost layer in the tension side region TR of the fiber reinforced resin material M. Therefore, the second reinforcing fiber layer group 2 can most effectively improve the strength of the fiber reinforced resin material M. Even if the second reinforcing fiber layer group 2 is not the outermost layer, the strength of the fiber reinforced resin material M can be improved as long as it is arranged in the tension side region TR. However, by arranging the second reinforcing fiber layer group 2 in the outermost layer where the tensile stress in the fiber reinforced resin material M generated due to the external force F is greatest, the bending strength of the fiber reinforced resin material M can be most effectively improved.

[0026] It has also been found that the bending strength is improved when the second reinforcing fiber layer group 2 is used only in the outermost layer of the tension-side region TR, as in this embodiment, rather than when the fiber-reinforced resin material M is formed only from a large number of second reinforcing fiber layers 2a. This is because when the fiber-reinforced resin material M is formed only from a large number of second reinforcing fiber layers 2a, layer delamination due to compressive failure is likely to occur in the second reinforcing fiber layers 2a in the compression-side region CR. When strength alone is considered, when the second reinforcing fiber layer group 2 is arranged in the tension-side region TR, the strength of the fiber-reinforced resin material M can be improved by arranging only the first reinforcing fiber layer 1 in the compression-side region CR.

[0027] It has also been found that, as in this embodiment, when a single second reinforcing fiber layer group 2 is arranged in the tension side region TR and the remaining reinforcing fiber layers are first reinforcing fiber layers 1, the variation in strength of the fiber reinforced resin material M is small. Specifically, the CV (Coefficient of Variation) value of the strength of the fiber reinforced resin material M can be kept low. When only strength is considered, when the second reinforcing fiber layer group 2 is arranged in the tension side region TR, the variation in strength of the fiber reinforced resin material M can be suppressed by arranging the first reinforcing fiber layer 1 in the compression side region CR.

[0028] In this embodiment, only a single second reinforcing fiber layer group 2 is arranged in the tension side region TR. While a single second reinforcing fiber layer group 2 is preferable to reduce the number of layers, this does not prevent two or more second reinforcing fiber layer groups 2 from being arranged in the tension side region TR. For example, the following configuration may be used. A second reinforcing fiber layer group 2 is arranged in the outermost layer of the tension side region TR, and a first reinforcing fiber layer 1 is arranged adjacently inside it. Then, a second reinforcing fiber layer group 2 is arranged further inside this first reinforcing fiber layer 1. The remaining reinforcing fiber layers inside this second second reinforcing fiber layer group 2 and in the compression side region CR are first reinforcing fiber layers 1.

[0029] 4 shows a fiber-reinforced resin material M of a second embodiment. In this embodiment, a second reinforcing fiber layer group 2 is arranged in the compression-side region CR. Each first reinforcing fiber layer 1 of this embodiment has the same configuration as the first reinforcing fiber layer 1 of the first embodiment. Each second reinforcing fiber layer 2a of this embodiment also has the same configuration as the second reinforcing fiber layer 2a of the first embodiment. The second reinforcing fiber layer group 2 of this embodiment also has the same configuration as the second reinforcing fiber layer group 2 of the first embodiment. Therefore, redundant explanations thereof will be omitted.

[0030] By arranging the second reinforcing fiber layer group 2 in the compression-side region CR, the elastic modulus, i.e., hardness, of the fiber-reinforced resin material M can be improved. For example, by using the fiber-reinforced resin material M of this embodiment in the above-mentioned vehicle body panel material, deflection of the vehicle body panel material can be effectively suppressed. Furthermore, the fiber-reinforced resin material M of this embodiment has a bending strength higher than that of a fiber-reinforced resin material formed only with a plurality of first reinforcing fiber layers 1 (although it is lower than the strength of the fiber-reinforced resin material M of the first embodiment). It has been found that, in order to improve the elastic modulus (hardness) of the fiber-reinforced resin material M, it is more effective to arrange the second reinforcing fiber layer group 2 only in the compression-side region CR than to arrange it only in the tension-side region TR.

[0031] As described above, when the fiber-reinforced resin material M is formed with a large number of second reinforcing fiber layers 2a, the number of layers increases, making it difficult to improve productivity. In this embodiment, by using the second reinforcing fiber layer group 2 only in a portion of the fiber reinforced resin material M and using the first reinforcing fiber layer 1 in the remaining portion, it is possible to minimize the increase in the number of layers and improve productivity, while also improving the elastic modulus (hardness) of the fiber-reinforced resin material M with the second reinforcing fiber layer group 2. Furthermore, because the second reinforcing fiber layer group 2, which has a high fiber volume fraction Vf of carbon fiber, is only used in a portion of the fiber reinforced resin material M, it is possible to minimize the increase in the amount of expensive carbon fiber used and suppress an increase in the production cost of the fiber-reinforced resin material M.

[0032] In particular, in this embodiment, the second reinforcing fiber layer group 2 is used as the outermost layer in the compression-side region CR of the fiber-reinforced resin material M. Therefore, the second reinforcing fiber layer group 2 can most effectively improve the elastic modulus (hardness) of the fiber-reinforced resin material M. Even if the second reinforcing fiber layer group 2 is not the outermost layer, the elastic modulus (hardness) of the fiber-reinforced resin material M can be improved as long as it is arranged in the tension-side region TR. However, by arranging the second reinforcing fiber layer group 2 in the outermost layer, the bending hardness of the fiber-reinforced resin material M can be most effectively improved.

[0033] In this embodiment, only a single second reinforcing fiber layer group 2 is arranged in the compression-side region CR. While a single second reinforcing fiber layer group 2 is preferable to reduce the number of layers, this does not prevent two or more second reinforcing fiber layer groups 2 from being arranged in the compression-side region CR. For example, the following configuration may be used. A second reinforcing fiber layer group 2 is arranged in the outermost layer of the compression-side region CR, and a first reinforcing fiber layer 1 is arranged adjacently inside it. Then, a second reinforcing fiber layer group 2 is arranged further inside this first reinforcing fiber layer 1. The remaining reinforcing fiber layers inside this second second reinforcing fiber layer group 2 and in the tension-side region TR are first reinforcing fiber layers 1.

[0034] FIG. 5 shows a fiber-reinforced resin material M according to a third embodiment. In this embodiment, the second reinforcing fiber layer group 2 is disposed in both the tension-side region TR and the compression-side region CR. With this configuration, the flexural modulus (hardness) of the fiber-reinforced resin material M can be improved compared to the case in which the second reinforcing fiber layer group 2 is disposed only in the compression-side region CR as in the second embodiment. However, the flexural strength of the fiber-reinforced resin material M is inferior to the case in which the second reinforcing fiber layer group 2 is disposed only in the tension-side region TR as in the first embodiment, but is improved compared to the case in which the second reinforcing fiber layer group 2 is disposed only in the compression-side region CR as in the second embodiment. The reason why the flexural strength of the fiber-reinforced resin material M according to this embodiment is lower than that of the first embodiment is that delamination due to compression fracture is likely to occur in the second reinforcing fiber layer 2 a of the second reinforcing fiber layer group 2 in the compression-side region CR.

[0035] Therefore, the arrangement of the second reinforcing fiber layer group 2 as in this embodiment may be effective depending on the mechanical properties (strength and elastic modulus) required for the position in the vehicle body where the fiber-reinforced resin material M is used. Note that, although the second reinforcing fiber layer group 2 is arranged in each of the tension-side region TR and the compression-side region CR in this embodiment, this does not prevent an additional second reinforcing fiber layer group 2 from being arranged in addition to these two second reinforcing fiber layer groups 2.

[0036] In particular, in this embodiment, the second reinforcing fiber layer group 2 is used as the outermost layer in the tension-side region TR of the fiber-reinforced resin material M, and is also used as the outermost layer in the compression-side region CR of the fiber-reinforced resin material M. Therefore, the second reinforcing fiber layer group 2 can most effectively improve the elastic modulus (hardness) of the fiber-reinforced resin material M, and can also improve the strength to a certain extent, thereby enabling a balanced improvement in the mechanical strength of the fiber-reinforced resin material M.

[0037] In the first to third embodiments described above, the layer thickness of the second reinforcing fiber layer 2a is preferably 80 μm or more and 300 μm or less. The second reinforcing fiber layer 2a formed using the opened tows provides the above-mentioned improved mechanical properties by thinly spreading the filaments. If the thickness is less than 80 μm, the opened tows are too thin, reducing the linearity of the tows and making gaps more likely to occur between the reinforcing fibers during lamination. If gaps are more likely to occur, it becomes difficult to obtain the effect of improving the mechanical properties by increasing the fiber volume fraction Vf. Furthermore, if the thickness is less than 80 μm, the number of layers of the second reinforcing fiber layer 2a increases, making it difficult to obtain the effect of improving productivity. On the other hand, if the thickness exceeds 300 μm, it becomes difficult to obtain the above-mentioned effect brought about by thinning the layers by "opening."

[0038] In the first to third embodiments described above, the reinforcing fibers of the second reinforcing fiber layer 2a are preferably carbon fibers. Carbon fibers are lightweight among reinforcing fibers, and therefore can effectively contribute to reducing the weight of the vehicle body. Furthermore, carbon fibers have excellent fatigue resistance, chemical resistance, and corrosion resistance among reinforcing fibers, making them suitable for use in vehicle bodies. Furthermore, carbon fibers are excellent in terms of strength, and fiber-spreading techniques are easily applicable.

[0039] The present invention is not limited to the above embodiment. For example, Fig. 2 illustrates a case where the external force F that bends the fiber-reinforced resin material 100 acts in the thickness direction of the fiber-reinforced resin material 100, i.e., in the stacking direction of the reinforced fiber layers 101. However, the direction of the external force F that bends the fiber-reinforced resin material M is not limited to the thickness direction or the stacking direction. The fiber-reinforced resin material M may also be bent by an external force F acting from a direction other than the thickness direction or the stacking direction. Even in such a case, the "tension-side region TR" and the "compression-side region CR" may be defined by taking into account the bending form (inside / outside of the bend) of the fiber-reinforced resin material M.

[0040] In the above embodiment, the reinforcing fibers of the first reinforcing fiber layer 1 and the second reinforcing fiber layer 2a are carbon fibers. As described above, the reinforcing fibers of the second reinforcing fiber layer 2a are preferably carbon fibers, but the reinforcing fibers of the first reinforcing fiber layer 1 and the second reinforcing fiber layer 2a are not limited to carbon fibers. Other reinforcing fibers, such as glass fibers, aramid fibers, boron fibers, Kevlar fibers, and natural fibers, may also be used. The type of matrix resin of the fiber-reinforced resin material M is also not limited, and may be, for example, a thermosetting resin or a thermoplastic resin, as described above. Furthermore, the molding method of the fiber-reinforced resin material M is also not limited, and various molding methods using long reinforcing fibers, such as autoclave molding using prepregs and RTM molding, can be used.

[0041] M: Fiber reinforced resin material 1: First reinforcing fiber layer 2a: Second reinforcing fiber layer 2: Second reinforcing fiber layer group CP: Center plane (in the thickness direction of the fiber reinforced resin material M) TR: Tension side region CR: Compression side region F: External force

Claims

1. A fiber reinforced resin material for a vehicle body, A plurality of first reinforcing fiber layers formed by unspread reinforcing fiber bundles; a second reinforcing fiber layer group in which a plurality of second reinforcing fiber layers formed by opened reinforcing fiber bundles are continuously laminated; a matrix resin impregnated in the plurality of first reinforcing fiber layers and the plurality of second reinforcing fiber layers and reinforced by the plurality of first reinforcing fiber layers and the plurality of second reinforcing fiber layers, When an external force bending the fiber-reinforced resin material generates a load in the in-plane direction and a compressive force or a tensile force acts on the fiber-reinforced resin material, the region on the inside of the bend of the fiber-reinforced resin material relative to the center plane of the thickness of the fiber-reinforced resin material is defined as a compression side region where compressive stress acts, and the region on the outside of the bend of the fiber-reinforced resin material is defined as a tension side region where tensile stress acts. This fiber-reinforced resin material is such that the second reinforcing fiber layer group is arranged only in the tension side region.

2. A fiber reinforced resin material for a vehicle body, A plurality of first reinforcing fiber layers formed by unspread reinforcing fiber bundles; a second reinforcing fiber layer group in which a plurality of second reinforcing fiber layers formed by opened reinforcing fiber bundles are continuously laminated; a matrix resin impregnated in the plurality of first reinforcing fiber layers and the plurality of second reinforcing fiber layers and reinforced by the plurality of first reinforcing fiber layers and the plurality of second reinforcing fiber layers, When an external force bending the fiber-reinforced resin material generates a load in the in-plane direction and a compressive force or a tensile force acts on the fiber-reinforced resin material, the region on the inside of the bend of the fiber-reinforced resin material relative to the center plane of the thickness of the fiber-reinforced resin material is defined as a compression side region where compressive stress acts, and the region on the outside of the bend of the fiber-reinforced resin material is defined as a tension side region where tensile stress acts. This fiber-reinforced resin material is arranged only in the compression side region.

3. The fiber reinforced resin material according to claim 1 or 2, A fiber reinforced resin material, wherein the second reinforcing fiber layer group is an outermost layer of the fiber reinforced resin material.

4. The fiber reinforced resin material according to any one of claims 1 to 3, A fiber reinforced resin material, wherein each of the plurality of second reinforcing fiber layers has a thickness of 80 μm or more and 300 μm or less.

5. The fiber reinforced resin material according to any one of claims 1 to 4, A fiber-reinforced resin material, wherein the reinforcing fibers of the reinforcing fiber bundles used in the plurality of second reinforcing fiber layers are carbon fibers.

6. A plurality of first reinforcing fiber layers formed by unspread reinforcing fiber bundles; a second reinforcing fiber layer group in which a plurality of second reinforcing fiber layers formed by opened reinforcing fiber bundles are continuously laminated; a matrix resin impregnated in the plurality of first reinforcing fiber layers and the plurality of second reinforcing fiber layers and reinforced by the plurality of first reinforcing fiber layers and the plurality of second reinforcing fiber layers; A vehicle body frame structural material, wherein the second reinforcing fiber layer group is arranged on the passenger compartment side with respect to a center plane of the thickness of the fiber reinforced resin material.

7. The vehicle body frame structural material according to claim 6, A vehicle body frame structure material, wherein the second reinforcing fiber layer group is an outermost layer of the fiber reinforced resin material.

8. The vehicle body frame structural material according to claim 6 or 7, A vehicle body frame structural material, wherein each of the plurality of second reinforcing fiber layers has a thickness of 80 μm or more and 300 μm or less.

9. The vehicle body frame structural material according to any one of claims 6 to 8, A vehicle body frame structural material, wherein the reinforcing fibers of the reinforcing fiber bundles used in the plurality of second reinforcing fiber layers are carbon fibers.

10. A plurality of first reinforcing fiber layers formed by unspread reinforcing fiber bundles; a second reinforcing fiber layer group in which a plurality of second reinforcing fiber layers formed by opened reinforcing fiber bundles are continuously laminated; a matrix resin impregnated in the plurality of first reinforcing fiber layers and the plurality of second reinforcing fiber layers and reinforced by the plurality of first reinforcing fiber layers and the plurality of second reinforcing fiber layers; The second reinforcing fiber layer group is disposed on the outer surface side of the vehicle body relative to a center plane of the thickness of the fiber reinforced resin material.

11. The vehicle body panel material according to claim 10, The vehicle body panel material, wherein the second reinforcing fiber layer group is the outermost layer of the fiber reinforced resin material.

12. The vehicle body panel material according to claim 10 or 11, A vehicle body panel material, wherein each of the plurality of second reinforcing fiber layers has a thickness of 80 μm or more and 300 μm or less.

13. The vehicle body panel material according to any one of claims 10 to 12, A vehicle body panel material, wherein the reinforcing fibers of the reinforcing fiber bundles used in the plurality of second reinforcing fiber layers are carbon fibers.