TW202411055A - Fiber-reinforced plastic and manufacturing method thereof - Google Patents

Abstract

The purpose of the present invention is to provide a fiber-reinforced plastic with a protrusion that is lightweight and has excellent mechanical properties and appearance quality. The fiber-reinforced plastic is composed of a plate-like portion and at least one protrusion that protrudes from at least one side of the plate-like portion. The plate-like portion has at least one layer (unidirectional layer) in which a plurality of reinforcing fibers are arranged in one direction in a base resin. The protrusion extends in at least two different directions, and at least two of the directions in which the protrusion extends are non-parallel and non-perpendicular to each other, and all the directions in which the protrusion extends are non-parallel and non-perpendicular to the fiber orientation direction in any one of the unidirectional layers in the plate-like portion.

Description

Fiber reinforced plastic and manufacturing method thereof

The present invention relates to a fiber-reinforced plastic having a plate-like portion and a protrusion protruding from at least one side of the plate-like portion, and to a fiber-reinforced plastic in which the plate-like portion and the protrusion are formed by a plurality of reinforcing fibers and a matrix resin.

Fiber-reinforced plastics, which are composed of reinforced fibers and base resins, have high specific strength and specific elastic modulus, excellent mechanical properties, and high functional properties such as weather resistance and chemical resistance. Therefore, they are expected to be used in a wide range of fields such as industry, sports, medicine, and information and communications, and are attracting attention.

In order to improve the mechanical properties of fiber-reinforced plastics and promote thin-wall and lightweight while maintaining the mechanical properties, the cross-sectional shape of the molded product is carefully designed, and fiber-reinforced plastics with varying wall thickness and rib shapes are designed. In particular, the rib shape is also effective in preventing the wide flat part of the molded product from warping, but the shape becomes complicated, so there are problems in terms of moldability and mass production.

There are two methods for manufacturing fiber-reinforced plastics with high functional properties: autoclave molding and press molding. In autoclave molding, a semi-hardened state in which a thermosetting resin as a matrix resin is impregnated into a sheet or fabric of continuous reinforcing fibers called a prepreg is laminated, and the matrix resin of the thermosetting resin is hardened by heating and pressurizing in a high-temperature autoclave (autoclave), thereby molding the fiber-reinforced plastic. In press molding, the laminated prepreg is placed in a mold, heated and pressurized by a press machine to harden the base resin of the thermosetting resin and form it, or a prepreg impregnated with a thermoplastic resin as the base resin is used, the thermoplastic resin is softened or melted and formed, and then cooled and demolded to form it. In particular, in press molding using a thermosetting resin, by using a prepreg in which a thermosetting resin with a fast curing speed as the base resin is impregnated with reinforcing fibers, it is possible to produce a large number of molded products in a short time, and therefore it has attracted attention as a highly productive molding method in recent years.

In the molding method using the above-mentioned prepreg, when manufacturing a molded product with a complex shape such as a shape with varying wall thickness or a shape with ridges, it is possible to divide the cross section of the desired fiber-reinforced plastic into a plate-shaped portion, a ridge-shaped portion, etc., and after each portion is molded separately, a method of bonding by adhesive or heat fusion is possible. However, the subsequent step is time-consuming and costly, and the strength and rigidity of the joint portion become lower than that of the other portions, so the joint portion will break first, and it is difficult to fully exert the excellent mechanical properties and durability of the fiber-reinforced plastic.

On the other hand, there is also a method of shaping on a mold before forming, making a preform and then forming. This method can solve the problem of cracking caused by the above-mentioned joint, but the shaping step is time-consuming, so production efficiency and cost become issues.

Furthermore, in the case of a fiber-reinforced plastic made of short fibers with a length of several to several tens of millimeters, it is relatively easy to form a protrusion. For example, if the base resin is a thermosetting resin, there are press molding methods such as SMC (sheet molding plastic) and BMC (block molding material), and if it is a thermoplastic resin, injection molding can be used. However, in the case of SMC and BMC, uneven distribution and orientation of the reinforcing fibers will inevitably occur during their manufacturing steps, so there are problems such as reduced mechanical properties of the molded product or increased variation in the values of its physical properties. Furthermore, in injection molding, the amount of reinforcing fibers is small, and molding is impossible without using short reinforcing fibers, so the mechanical properties of the molded product become very low. Therefore, with these methods, it is difficult to manufacture fiber-reinforced plastics with protrusions suitable for components that particularly require high mechanical properties and durability.

Attempts to improve the problems of the prior art have been proposed (Patent Documents 1 and 2).

Patent document 1 proposes a method for manufacturing fiber-reinforced plastics, wherein a prepreg substrate adjusted to a fiber length of 10 to 100 mm is inserted, laminated in at least two sheets, and press-formed to form the shape of the ridges. However, even in the prepreg substrate formed by inserting the cutouts, the elongation of the substrate and the fluidity of the fibers in the fiber direction and in the direction perpendicular to the fibers are different. Therefore, depending on the shape of the fiber-reinforced plastic and the ridges, there are cases where the fibers and resin are not filled into the ridge portion of the mold, which is "unfilled", and where only the resin is extruded from the prepreg, which is "resin enriched".

Furthermore, Patent Document 2 discloses that in a fiber-reinforced plastic composed of a laminate of a fabric prepreg and a discontinuous fiber prepreg, when the heat generation of the resin of each prepreg satisfies the specified conditions, a fiber-reinforced plastic with less fabric disturbance can be obtained. However, since the fabric prepreg disposed on the design surface is hardened first, there is a possibility of fading and pinholes due to insufficient resin flow, and the surface smoothness and appearance quality are impaired. [Prior Technical Document] [Patent Document]

Patent document 1: International Publication No. 2008/038429 Patent document 2: International Publication No. 2019/031111

[Problems to be solved by the invention]

The purpose of the present invention is to provide a fiber-reinforced plastic with protrusions that is lightweight and has excellent mechanical properties and appearance quality to improve the problems of the previous technology. [Means for solving the problem]

The present invention for achieving the above object is any of the following: (1) A fiber-reinforced plastic having a plate-like portion and at least one protrusion protruding from at least one side of the plate-like portion, wherein the plate-like portion has at least one layer (unidirectional layer) in which a plurality of reinforcing fibers are arranged in one direction in a matrix resin, the protrusion extending in at least two different directions, at least two of the directions in which the protrusion extends are not parallel to or perpendicular to each other, and all the directions in which the protrusion extends are not parallel to or perpendicular to the fiber orientation direction in any one of the unidirectional layers in the plate-like portion. (2) A fiber-reinforced plastic as described in (1) above, which has at least one unidirectional layer whose fiber orientation direction is non-parallel and non-vertical relative to the direction in which the protrusion extends. (3) A fiber-reinforced plastic as described in (1) or (2) above, wherein the plate-like portion has at least two unidirectional layers, and the fiber orientation directions of the two unidirectional layers are non-parallel to each other. (4) A fiber-reinforced plastic as described in any one of (1) to (3) above, wherein the plate-like portion has at least two unidirectional layers, and the fiber orientation directions of the two unidirectional layers are perpendicular to each other. (5) A fiber-reinforced plastic as described in any one of the above (1) to (4), wherein the angle formed by all directions in which the above-mentioned protrusions extend and the fiber orientation direction in any one of the unidirectional layers in the above-mentioned plate-like portion is 15° to 80° or 100° to 165°. (6) A fiber-reinforced plastic as described in any one of the above (1) to (5), wherein at least one layer of the above-mentioned unidirectional layers located inside the above-mentioned plate-like portion has a fiber basis weight of not less than 70 g/ ^m2 and not more than 200 g/ ^m2 . (7) A fiber-reinforced plastic as described in any one of the above (1) to (6), wherein at least one layer of the above-mentioned unidirectional layers located inside the above-mentioned plate-like portion contains reinforcing fibers with a fiber length of 10 to 300 mm. (8) A fiber-reinforced plastic as described in any one of (1) to (7) above, wherein the interior of the plate-like portion comprises two or more unidirectional layers having different fiber basis weights. (9) A fiber-reinforced plastic as described in (8) above, wherein the outermost layer on the side of the protrusion in the plate-like portion is a unidirectional layer, and the fiber basis weight of the unidirectional layer being the outermost layer is smaller than the fiber basis weight of at least one other unidirectional layer in the plate-like portion. (10) A fiber-reinforced plastic as described in any one of (1) to (9) above, wherein the plate-like portion has a plurality of layers consisting of reinforcing fibers and a matrix resin, only one side of the plate-like portion has the protrusion, and at least one of the layers other than the outermost layer of the surface having the protrusion is a layer (non-unidirectional layer) in which a plurality of reinforcing fibers are oriented in at least two directions in the matrix resin. (11) A fiber-reinforced plastic as described in any one of (1) to (10) above, wherein the plate-like portion has a plurality of layers consisting of reinforcing fibers and a matrix resin, only one side of the plate-like portion has the protrusion, and the reinforcing fibers forming the outermost layer of the surface on the opposite side are fabric. (12) A method for producing a fiber-reinforced plastic, comprising placing at least one layer of a prepreg formed by impregnating a matrix resin into a plurality of reinforcing fibers arranged in one direction in a mold, closing the mold and applying heat and pressure, thereby obtaining a fiber-reinforced plastic as described in any one of the above (1) to (11). [Effect of the Invention]

According to the present invention, a fiber-reinforced plastic having a protrusion which is lightweight and has excellent mechanical properties and appearance quality can be provided.

[Form used to implement the invention]

The fiber-reinforced plastic of the present invention has at least one layer (hereinafter sometimes referred to as a unidirectional layer) in which a plurality of reinforcing fibers are arranged in one direction in a base resin. For example, as shown in FIG. 2 , the fiber-reinforced plastic is formed by a plate-like portion 100 and at least one protrusion (two locations a and b in FIG. 2 ) protruding from at least one side of the plate-like portion 100. In the present invention, the protrusion extends in at least two different directions. The directions in which the protrusion extends are described below.

The shape of the protrusion when the protrusion is observed from above the surface of the plate-like portion is set as the plane shape of the protrusion, the direction in which the plane shape of the protrusion extends is set as the direction in which the protrusion extends (hereinafter, sometimes referred to as the length direction), and the direction perpendicular to the length direction on the plane shape is set as the width direction of the protrusion. The direction in which the plane shape extends here refers to the direction of the long axis when the plane shape is an elliptical shape, and refers to the direction of the long side when the plane shape is a rectangular shape. When the plane shape is a shape other than the above, it is set to the direction of the long side of the rectangle with the smallest area circumscribed with the shape. Furthermore, a section in which the length direction of the protrusion is parallel to the length direction of the protrusion and perpendicular to the plane direction of the plate-shaped portion as much as possible is referred to as a cross-section of the protrusion, and a section in which the width direction of the protrusion is parallel to the width direction of the protrusion and perpendicular to the plane direction of the plate-shaped portion as much as possible is referred to as a longitudinal section of the protrusion. As an example, when the plane shape of the protrusion is an ellipse as shown in FIG. 1 , the long axis direction of the ellipse becomes the long direction 20 of the protrusion, the short axis direction becomes the width direction 21 of the protrusion, the section perpendicular to the plane direction of the plate-shaped portion along the long axis becomes the cross-section 22 of the protrusion, and the section perpendicular to the plane direction of the plate-shaped portion along the short axis becomes the longitudinal section 23 of the protrusion.

In the present invention, the protrusion extends in at least two different directions. That is, as an example, it means a protrusion having two or more protrusions extending in different directions as shown in FIG. 2, or a protrusion having a planar shape (X-shaped, V-shaped, H-shaped (except for those in which all directions of extension are perpendicular or parallel) or Y-shaped, etc.) formed by combining two or more planar shapes extending in different directions. That is, when the planar shape of the protrusion is X-shaped or V-shaped, it is interpreted as having two longitudinal directions, and when it is H-shaped or Y-shaped, it is interpreted as having three longitudinal directions, and the above-mentioned planar shape is decomposed into a plurality of shapes based on them, and is interpreted as having a plurality of cross sections and longitudinal sections corresponding to each direction.

In the present invention, at least two different directions in which the protrusion extends are not parallel or perpendicular to each other. Here, "not parallel or perpendicular" means that they are not parallel or perpendicular to each other, which means that when any direction is set to 0°, the other directions are not 0° or 90°.

Furthermore, the fiber reinforced plastic of the present invention is characterized in that the plate-shaped portion has at least one layer (unidirectional layer) in which a plurality of reinforcing fibers are arranged in one direction in a matrix resin. The above-mentioned unidirectional layer can be any portion that constitutes the plate-shaped portion, and can also be a portion that constitutes the surface layer, or can also be an inner layer portion other than the surface layer. In addition, in the present invention, the material that is equivalent to the unidirectional layer before the fiber reinforced plastic is formed is referred to as a unidirectional prepreg.

In the present invention, all directions in which the protrusions extend are not parallel or perpendicular to the fiber orientation direction in any unidirectional layer in the aforementioned plate-like portion (i.e., not parallel or perpendicular). In other words, the above requirements refer to a unidirectional layer having a fiber orientation direction that is not parallel or perpendicular to the direction in which each protrusion extends. If Figure 2 is cited as an example, if the plate-like portion has: a unidirectional layer having a fiber orientation direction that is not parallel or perpendicular to the direction in which the protrusion a extends, and a unidirectional layer having a fiber orientation direction that is not parallel or perpendicular to the direction in which the protrusion b extends, then the above requirements are met. Here, even if one layer (or a plurality of layers) has a fiber orientation direction that is not parallel or perpendicular to any of the two directions in which the protrusions a and b extend, the above requirements are still met, which is one of the preferred aspects.

Furthermore, the so-called "the direction in which the protrusion extends is not parallel or perpendicular to the fiber orientation direction of the unidirectional layer" means that the fiber orientation direction is inclined relative to the length direction of the protrusion. That is, for example, in (A) to (C) of Figure 9, the reinforcing fibers constituting the unidirectional prepreg are shown to extend along the length direction of the protrusion (rib direction, paper depth direction) or in a direction perpendicular thereto, but it is not set to such a state. For example, Figure 9 (D) means that the reinforcing fibers do not extend along the longest direction of the protrusion or in a direction perpendicular thereto.

In addition, Fig. 9 (A) shows a state where the reinforcing fiber 300 is parallel to the length direction (rib direction) of the protrusion 200, Fig. 9 (B) shows a state where the reinforcing fiber 300 is perpendicular to the length direction (rib direction) of the protrusion 200, and Fig. 9 (C) shows a state where the reinforcing fiber 300 is parallel and perpendicular to the length direction (rib direction) of the protrusion 200. On the other hand, Fig. 9 (D) is a state where the reinforcing fiber 300 is neither parallel nor perpendicular to the length direction (rib direction) of the protrusion 200, so the cross section of the reinforcing fiber 300 appears to be flat.

When the fiber orientation direction of the unidirectional layer is parallel to the length direction of the protrusion, it becomes difficult for the protrusion to bear the load in the shear direction. Therefore, the strength of the protrusion is insufficient, and cracks are easily generated inside the protrusion along the alignment direction of the reinforcing fibers, and the possibility of the protrusion breaking and peeling off from the plate-like portion becomes higher. In addition, when the fiber orientation direction of the unidirectional layer is perpendicular to the length direction of the protrusion, it becomes difficult for the reinforcing fibers to flow into the inside of the protrusion (the concave part of the mold) during molding, so the possibility of unfilled areas of reinforcing fibers in the protrusion after molding becomes higher. In addition, if the reinforcing fibers become difficult to flow, the matrix resin is squeezed out of the unidirectional prepreg, and the possibility of partially generating resin-only areas (resin-rich areas) also becomes higher.

In contrast, in the fiber-reinforced plastic finally obtained, all directions in which the protrusions extend are not parallel or perpendicular to the fiber orientation direction in any unidirectional layer in the plate-like portion (i.e., for each extension direction, at least one unidirectional layer is provided in which the fiber orientation direction is not parallel or perpendicular to the extension direction of the protrusions), which means that the number of reinforcing fibers extending along each extension direction of the protrusions is reduced. Therefore, according to the present invention, it is possible to suppress the occurrence of depressions 500 in the protrusion of the fiber-reinforced plastic along the fiber alignment direction as shown in FIG. 9(A), the occurrence of "unfilled" areas 600 of the fiber and resin as shown in FIG. 9(B) and (C), and the occurrence of "resin enrichment", thereby making it possible to simultaneously seek to improve the appearance quality while improving mechanical properties such as strength.

In addition, in the present invention, as long as the protrusions extend in directions that are in such a relationship with the orientation direction of the reinforcing fibers, a unidirectional layer is sufficient, but preferably at least one layer of protrusions extends in directions that are in such a relationship with the orientation direction of the reinforcing fibers. By having such a layer, the fiber filling property of the protrusions is improved, and the carbon fibers connected to the plate-like portion can be filled into the interior of each ridge, thereby obtaining a molded product with excellent mechanical properties.

Furthermore, in the present invention, by making the protrusions themselves extend in two or more different directions and configuring the protrusions to be non-parallel and non-perpendicular to each other, even when a unidirectional layer is simply laminated in such a manner that the fiber orientation direction (°) in the plate-like portion becomes [0/90], the fiber orientation direction in the plate-like portion can still be made non-parallel and non-perpendicular relative to the extending direction of the protrusions, so that the width of the laminated structure becomes wider, and a molded product with protrusions having excellent mechanical properties and excellent appearance quality can be obtained.

In the present invention, the plate-like portion has at least two unidirectional layers, and the fiber orientation directions of the two unidirectional layers are perpendicular to each other, which is one of the preferred aspects. For example, the fiber orientation direction (°) is [+45/-45], [+30/-60], [+50/-40], etc., but it is not particularly limited to these. In addition, as a whole, the laminated structure of the plate-like portion has a symmetrical laminated structure, which can reduce the warping of the plate-like object (fiber reinforced plastic) itself and is preferred.

In addition, as long as the angle between the fiber orientation direction and the length direction (extension direction) of the protrusion (the angle formed by the orientation direction of the reinforcing fiber and the length direction of the protrusion) is not parallel or perpendicular, it is not particularly limited, but preferably 15° to 80° or 100° to 165°. That is, among 0 to 90°, 15 to 80° is preferred. In addition, from the perspective of the filling property of the protrusion and the bonding strength between the protrusion and the plate-shaped portion, among 0 to 90°, 20 to 70° is more preferred, and 30 to 60° is further preferred.

The details will be described later, but the plate-like part and the protrusion can be obtained by preparing, for example, a plurality of unidirectional prepregs, sequentially stacking the prepregs in the desired direction, and pressing the laminate (preform). In addition, when making the laminate (preform), it can be shaped in a predetermined shape as needed. After that, the laminate can be put into a preheated mold (for example, a concave mold), heated and pressed by a press machine, and formed to obtain a fiber-reinforced plastic.

The shape of the plate-like portion is not particularly limited. The thickness can be arbitrarily designed by adjusting the amount of fiber and matrix resin used. In addition to adjusting the number of layers of the unidirectional prepreg, it is also possible to arbitrarily adjust by changing the amount of resin impregnated in the unidirectional prepreg or changing the type of fiber.

When the fiber-reinforced plastic of the present invention is used in structural members, outer panels such as covers, and other parts used in transportation equipment such as automobiles and motorcycles, sports equipment such as bicycles and golf clubs, and medical equipment, the thickness of the plate portion is preferably 0.1 to 10 mm from the perspective of both the required mechanical properties and lightweight and practicality. It is more preferably 0.3 to 1.8 mm, and further preferably 0.5 to 1.2 mm. When used for applications that particularly require lightweighting, it is preferably 0.5 to 1.2 mm.

The shape of the protrusion protruding from the plate-like portion is not particularly limited as long as it extends in at least two different directions as described above, and at least two of the extending directions are not parallel to each other and not perpendicular to each other, and various shapes can be adopted according to the purpose. For example, in addition to the protrusions having a Y shape as shown in FIG. 10(A), an X shape as shown in FIG. 10(B), an H shape as shown in FIG. 10(C), and a V shape as shown in FIG. 10(D) when viewed from the top of the plate-like portion, protrusions having polygonal shapes can also be listed. Moreover, these can also be combined.

In addition, as described above, when the protrusion has a planar shape that can combine two or more planar shapes extending in different directions, it is interpreted that the protrusion has two or more different extending directions. For example, in the case of a protrusion having a Y-shaped planar shape as shown in FIG. 10(A), it is interpreted that the protrusion extends in three directions, namely, extension direction 203, extension direction 204, and extension direction 205. Moreover, when the protrusion of FIG. 10(A) is used in the present invention, as long as there is a unidirectional layer in which the extension direction 203 is not parallel or perpendicular to the fiber orientation direction, a unidirectional layer in which the extension direction 204 is not parallel or perpendicular to the fiber orientation direction, and a unidirectional layer in which the extension direction 205 is not parallel or perpendicular to the fiber orientation direction in the plate-like portion, at this time, any two of the above three unidirectional layers may be the same unidirectional layers, or all of them may be the same unidirectional layers.

The cross-sectional shape and the longitudinal cross-sectional shape of the protrusion may be, for example, a polygon (eg, a rectangle), a triangle, or a semicircle.

Regarding the cross-sectional shape and height dimensions of the protrusions, it is possible to set all of the multiple protrusions to the same shape/size, but it is also possible to change it in accordance with the convex and concave shapes and curvature of the fiber-reinforced plastic, and it is also possible to partially produce a portion without the aforementioned shape and size ratio.

In the fiber-reinforced plastic of the present invention, the height of the protrusion (symbol 3 in FIG. 1 ) is not particularly limited and can be arbitrarily designed, but is preferably 0.1 to 50 mm. If the height of the protrusion is higher than 50 mm, there is a possibility that the unidirectional prepreg is not filled to the front end of the protrusion and there is an unfilled portion. Furthermore, if the height of the protrusion is lower than 0.1 mm, there is a possibility that the rigidity required for the molded product is reduced and the required mechanical properties cannot be obtained. The height of the protrusion is more preferably 0.1 to 20 mm, further preferably 1 to 10 mm, and most preferably 0.1 to 5 mm.

On the other hand, the width of the protrusion (symbol 1 in FIG. 1 ) is not particularly limited and can be arbitrarily designed according to the required strength and design. In addition, from the perspective of weight reduction, a narrower one is preferred, but from the perspective of reinforcing the plate-shaped portion, for example, the width of the protrusion is preferably 0.5 to 8 mm relative to the thickness of the plate-shaped portion of 0.1 to 1.8 mm. It is further preferably 0.5 to 3 mm, and most preferably 0.5 to 1.5 mm.

The fiber reinforced plastic of the present invention can arrange the protrusion at any place of the plate-shaped part. Moreover, the arrangement position of the protrusion can be confirmed in a top view of the fiber reinforced plastic that can confirm the appearance of the protrusion in its entirety. It is possible to arrange the protrusion at two or more places. That is, it is possible to set the protrusions of the same shape or different shapes at two or more places.

In addition, regarding the number of protrusions, in the top view, it is determined that the portion of the plate-like portion that can be seen is not equivalent to the protrusion, and the smallest protrusion surrounded by the plate-like portion is recognized as an independent protrusion and counted.

When ribs are provided as protrusions, in order to achieve both lightweighting and stiffness enhancement of the fiber-reinforced plastic of the present invention, it is preferred to configure ribs in not only one place but in two or more places. By doing so, the reinforcement range of the plate-shaped part can be expanded. Furthermore, when ribs are arranged in two or more places, each rib can be provided discontinuously and intermittently.

The fiber-reinforced plastic of the present invention is characterized in that at least one layer of a unidirectional prepreg in which a plurality of reinforcing fibers are arranged in sequence along one direction is arranged inside at least the plate-shaped portion, as described above, and the fiber orientation direction of any unidirectional prepreg is not parallel or perpendicular to the directions in which the protrusions extend. Here, the so-called "inside the plate-shaped portion" can be any portion equivalent to the plate-shaped portion, and can also be a portion constituting the surface layer, or can also be an inner layer portion other than the surface layer.

When laminating two or more layers of unidirectional prepreg, it is preferred that the fiber orientation directions between the layers are perpendicular to each other. That is, it is preferred that the plate-like portion has at least two layers of the aforementioned unidirectional layers, and the fiber orientation directions of the two unidirectional layers are perpendicular to each other. By setting the fiber orientation between the layers to be perpendicular, the warp and twist of the resulting molded product can be reduced. Furthermore, since the warp and twist can be reduced, the warp and twist correction steps of the molded product can also be reduced. In addition, depending on the desired properties of the composite material, the relationship between the layers can be freely determined, and a state in which they are not perpendicular to each other is not excluded.

The lamination order of the unidirectional prepreg may be set arbitrarily, but from the viewpoint of formability, it is preferable to perform lamination in such a manner that a layer that is neither parallel nor perpendicular to the longitudinal direction of the protrusion is located close to the protrusion. It is preferable to arrange the unidirectional prepreg within the fourth layer from the surface with the protrusion in the plate-shaped portion, and it is most preferable to arrange the unidirectional prepreg on the outermost layer of the surface on the side with the protrusion. It is also preferable to arrange all layers from the outermost layer to the second layer on the side with the protrusion, and from the outermost layer to the fourth layer, as layers that are neither parallel nor perpendicular to the longitudinal direction of the protrusion.

Furthermore, the number of layers of the unidirectional prepreg can be increased. The more layers of the unidirectional prepreg, the more fibers flow in the protrusions, which is better. It is preferably 4 layers or more, and more preferably 6 layers or more. By laminating in this way, the reinforcing fibers flow easily in the protrusions and it becomes easy to fill the reinforcing fibers to the end of the protrusions, which is better from the perspective of formability and the mechanical properties of the protrusions.

The unidirectional prepreg may be arranged in a manner that at least the orientation direction of the fibers satisfies the aforementioned aspects, but in the present invention, at least a portion of the plate-like portion has a structure formed by laminating two or more layers of unidirectional prepreg, and the fiber directions of the 2 unidirectional prepreg layers (the fiber orientation directions of the unidirectional layers) selected arbitrarily are not parallel to each other (not parallel), which is also one of the preferred aspects. That is, it is preferred to have a structure formed by laminating at least two layers of reinforcing fibers arranged in one direction, and the orientation directions of the reinforcing fibers in the 2 layers selected arbitrarily from the layers are not parallel to each other. When the orientation direction of the reinforcing fiber is only one direction, the protrusion is easy to warp due to the anisotropy of the thermal shrinkage rate and the linear expansion coefficient, and the dimensional accuracy will be deteriorated. Furthermore, when the protrusion is a rib, when the rib is subjected to forces in two directions or twisting forces, it becomes impossible to improve the durability of the rib against external forces.

Furthermore, when multiple unidirectional layers (reinforced fiber layers) having different orientation directions of reinforced fibers are laminated, it is generally said that the angle (°) of the fiber orientation direction becomes a symmetrical laminate such as [0/90] _ns , an isotropic laminate such as [0/±60] _ns , or [+45/0/-45/90] _ns , and that a symmetrical laminate structure is also provided in the lamination direction (thickness direction), which is effective in reducing the warp of the plate-like portion of the fiber-reinforced plastic. On the other hand, in the fiber-reinforced plastic of the present invention, by making the protrusions into rib shapes, the warp can be reduced, so it is possible to make the fiber orientation direction biased towards the rigidity direction required for the fiber-reinforced plastic.

Furthermore, in the present invention, it is preferred that the fiber length of the reinforcing fiber in at least one unidirectional layer located inside the plate-shaped portion (especially the outermost unidirectional layer located on the side of the protrusion) be 10 to 300 mm. By making the fiber length within this range, the reinforcing fiber becomes easy to follow the shape of the protrusion of the molded product, and the formability to three-dimensional shapes is improved. In addition, the disorder of the fiber arrangement during shaping and molding is reduced, so that a fiber-reinforced plastic with small variation in mechanical properties and high surface smoothness can be obtained.

Specifically, by setting the fiber length to 300 mm or less, the flexibility and fluidity of the reinforced fiber will be improved, and excellent shapability and formability can be obtained. On the other hand, if the fiber length is set to 10 mm or more, the distance between the cuts will be widened, and the cracks generated when the fiber-reinforced plastic is loaded with a high load will be difficult to connect, thus becoming a fiber-reinforced plastic with high mechanical properties and durability.

In addition, when the fiber length is adjusted by cutting the reinforced fiber with a knife, the reinforced fiber moves when the knife contacts the reinforced fiber, and there is a possibility that the fiber is separated from the knife and the fiber is caught in the knife. Therefore, it is believed that there are fibers that are not within the above range, but by adjusting the fiber length of most reinforced fibers to the above range, a sufficient improvement effect can be expected. In addition, there are fibers that are cut by contacting the edge of the mold during molding, so there are also situations where there are fibers shorter than the above range inside the molded product.

The fiber length of the reinforcing fiber can be adjusted within the aforementioned range by adjusting the fiber length of all reinforcing fibers in the fiber-reinforced plastic. However, sufficient effects can be obtained even by adjusting only the fiber length of the portion where the shape of the fiber-reinforced plastic such as the protrusion is changed and the reinforcing fibers around it.

With regard to the embodiment of the unidirectional prepreg in which reinforcing fibers having a fiber length of 10 to 300 mm are arranged in one direction and used in the present invention, for example: (1) a discontinuous reinforcing fiber obtained by a spinning method such as stretch spinning is impregnated with a matrix resin and is formed into a sheet; (2) a discontinuous reinforcing fiber (e.g., short fiber) is impregnated with a matrix resin and is arranged in one direction and is formed into a sheet; or (3) a unidirectional prepreg composed of continuous reinforcing fibers is formed with continuous or intermittent incisions of a limited length in a direction that crosses the reinforcing fibers, for example as shown in FIGS. 3 to 7 (a prepreg with an inserted incision).

The so-called (1) stretch spinning is a spinning method that applies tension to continuous fibers in a strand state and cuts the fibers into short fiber units. It has the characteristic that the cut points of the short fibers are not concentrated in one place, but are evenly dispersed over the entire length of the strand. The cut ends of the reinforcing fibers are randomly arranged to form aggregates without being neatly arranged in single fiber units. The reinforcing fibers flow in single fiber units, so the formability is slightly poor, but the stress transmission is completed very efficiently, making it possible to exhibit extremely high mechanical properties. In addition, the cut points of the reinforcing fibers are dispersed, making it possible to achieve excellent quality stability.

(2) The method of arranging discontinuous reinforcing fibers (e.g. short fibers) in one direction and forming a sheet is to arrange the cut ends of the reinforcing fibers in a regular and correct manner in a plurality of fiber units to form an aggregate. Since the arrangement and distribution of the reinforcing fibers are inevitably uneven, the quality stability is slightly poor, but since the fibers flow in a plurality of fiber units, it is possible to achieve extremely excellent formability.

(3) The method of using a prepreg with an inserted slit is to strengthen the correct arrangement of the fiber rules, so the quality stability and mechanical properties are excellent. Since the flow is carried out in units of multiple fibers, the formability is also excellent.

The above three aspects (1), (2) and (3) can be appropriately selected according to the application. Any one of them has an excellent balance between mechanical properties and formability and can be easily manufactured, but the aspect (3) is the best, in which continuous or intermittent incisions of limited length are cut into the entire surface of the unidirectional prepreg composed of continuous reinforcing fibers in the direction of transverse cutting of the reinforcing fibers.

Furthermore, there is no particular limitation on the method of making incisions in the prepreg. For example, a method of making incisions manually using a cutter is also possible, but a method of mechanically making incisions using an automatic cutting machine that has stable quality and can be mass-produced is preferred. There is no particular limitation on the method of mechanically making incisions. Examples include: a method of inserting incisions at a specified position using a cutting machine that moves a knife on a prepreg substrate spread out on a table, a method of inserting incisions corresponding to a pulse cycle by rolling a perforated rotating circular knife along a straight line, or a pulse laser used for high-speed scanning laser processing along a straight line, etc. Any one of the methods is a highly productive incision insertion method, and it is possible to select it according to the production equipment etc.

The prepreg after such steps is provided with a plurality of intermittent cuts in the direction of transversely cutting at least a portion of the reinforcing fibers, and as a result, the fiber length of at least a portion of the reinforcing fibers becomes 10 to 300 mm. Moreover, by intermittent cuts, the reinforcing fibers are actually all cut, and the shapeability and fluidity of the fibers during forming can be ensured.

The length of the cut is preferably defined as the projection length Ws of the projection plane perpendicular to the reinforcing fiber in the plane of the prepreg substrate, and is preferably in the range of 30μm to 1.5mm. However, since the substrate is deformed during shaping and forming, the cut may become longer where the substrate is extended and shorter where the substrate is crushed by compression. Therefore, if the fiber-reinforced plastic after forming is observed, there are places where the length of the cut is not within the above-mentioned range. However, by finally having a structure in which reinforcing fibers with a fiber length of 10 to 300 mm are correctly arranged in a regular manner in the fiber-reinforced plastic, a molded product with excellent mechanical properties and surface appearance can be obtained.

By reducing Ws, the amount of reinforcing fibers cut by each incision is reduced, and the strength can be expected to be improved. In particular, by setting Ws to 1.5 mm or less, a significant improvement in strength can be expected. On the other hand, when Ws is smaller than 30 μm, it is difficult to control the incision position, the variation in the fiber length of the reinforcing fibers increases, the reinforcing fibers with lengths outside the specified range increase, and the shapeability and fluidity decrease.

Here, the so-called "projected length Ws projected on a projection plane perpendicular to the reinforcing fibers" refers to the length of the incision when it is projected perpendicularly (fiber orientation direction 5) on a projection plane that exists in a direction perpendicular to the orientation direction of the reinforcing fibers (fiber perpendicular direction 6) within the plane of the prepreg in which the incision is inserted, as shown in Figures 3, 5, 6, and 7.

When the angle formed by the cut of the prepreg substrate and the reinforcing fiber is set to θ, the absolute value of θ is preferably in the range of 2 to 25°. By setting the absolute value of θ to 25° or less, the mechanical properties can be improved, especially the tensile strength can be improved. From this point of view, the absolute value of θ is preferably 15° or less. On the other hand, if the absolute value of θ is less than 2°, it may be difficult to cut the cut stably. That is, if the cut is flush with the reinforcing fiber, the reinforcing fiber will easily separate from the knife when cutting the cut, and the position accuracy of the cut will decrease. From this point of view, the absolute value of θ is preferably 5° or more.

As for the method of inserting the incision, it is possible to adopt either a method of continuously inserting at the aforementioned angle as shown in FIG. 4 or a method of intermittently inserting the incision at a plurality of locations as shown in FIGS. 5 to 7. In the case of continuous incision, the fiber length can be controlled to be constant, and the variation of mechanical properties and three-dimensional shape tracking can be reduced. On the other hand, in the case of intermittent insertion of the incision, by making the incision angle inclined relative to the reinforcing fiber, the projection length Ws formed by projecting the projection plane perpendicular to the reinforcing fiber in the plane of the prepreg substrate relative to the actual incision length Y can be reduced. Therefore, an extremely small incision of, for example, Ws=1.5 mm or less can be stably set industrially. Furthermore, the prepreg is less likely to be separated than a continuous cut during lamination, and the handling properties as a prepreg are also excellent.

As for the preferred cutting pattern of the prepreg with the cuts inserted, it can be listed as follows: as shown in FIG. 5, a plurality of intermittent oblique cuts 9 are provided in a direction that crosses the reinforcing fibers in at least a portion of the prepreg substrate. It is preferred that a plurality of intermittent oblique cuts 9 are inserted in a straight line to form a row 11, and the rows 11 are further arranged in a plurality and parallel to each other. By doing so, the distance between adjacent cuts can be maximized when the reinforcing fibers are of a fixed length, and as a result, the fiber-reinforced plastic can be homogenized while the strength is improved. The distance X between the rows is preferably in the range of 1 to 5 mm, for example.

When prepregs with inserted cuts are laminated, if the oblique cuts exist only in one direction, even if the prepregs have the same fiber direction, the directions of the cuts will be different when the prepregs are observed from the surface or from the back. Therefore, when manufacturing fiber-reinforced plastics, there is a possibility that the labor of controlling the direction of the cuts to be the same each time or the labor of controlling the lamination process for laminating the same number of sheets of the same fiber direction but with different cut directions will increase. However, if the absolute value of the slope of the cuts in the fiber direction is the same, and the cuts with positive angles and the cuts with negative angles each account for about half of the cutting pattern, it becomes possible to laminate with the same treatment as general continuous fiber prepregs.

As for other preferred cutting patterns of the prepreg with inserted cuts, there can be cited the embodiment as shown in FIG. 6. In this embodiment, a plurality of intermittent oblique cuts 9 are provided in the direction in which the reinforcing fibers are cross-cut in at least a portion of the prepreg substrate, and although the absolute value of θ of the oblique cuts 9 is substantially the same (uniform), oblique cuts 10 are provided at positive and negative relative angles. These oblique cuts 9 and 10 are provided approximately half each. Here, the definition of "substantially the same" in terms of the absolute value of θ is set to an angle deviation of within ±1°. In addition, the so-called approximately half refers to 45 to 55% (the same below) when expressed as a percentage based on the total number of oblique cuts 9 and 10.

As for the preferred implementation of the prepreg with the cut inserted, as shown in FIG6 , when focusing on any one cut A, among the cuts adjacent to the cut A, there are four or more cuts C with different sign of θ whose shortest distance to the cut A is closer than the closest cut B with the same sign of θ. When following the three-dimensional shape, the cut insertion part of the prepreg determines the movement of the fiber end by the relationship between the cut angle and the fiber direction. Therefore, since the adjacent cuts are of the same shape and angles in opposite directions, the isotropy in the plane after forming can be guaranteed in a macroscopic manner.

Furthermore, a preferred embodiment of the prepreg into which the cuts are inserted is preferably an embodiment as shown in FIG7 . In this embodiment, a plurality of intermittent oblique cuts 10 are provided in a direction in which the reinforcing fibers are cross-cut in at least a portion of the prepreg into which the cuts are inserted. Moreover, the intermittent oblique cuts 10 are inserted in a straight line shape and with substantially the same length Y, and the shortest distance between adjacent cuts is longer than the length Y of the cuts. The substantially same length referred to here means within a difference of ±5% (the same applies hereinafter). From the perspective of mechanical properties, when the cuts that are discontinuous points of the fibers are connected to each other by cracks, the fiber-reinforced plastic will break. By setting the cutting pattern to increase the distance between the cuts in the plane, there is an effect of suppressing the connection of cracks in at least the same plane, and the strength will be improved.

Furthermore, as for the preferred implementation of the prepreg with the cuts inserted, it can be listed as follows: a plurality of intermittent cuts are provided in the direction of the reinforcing fiber being cut across at least a portion of the prepreg with the cuts inserted, the intermittent cuts are inserted in a straight line and with substantially the same length Y, and the distance between adjacent cuts on the same straight line is greater than 3 times the length Y of the cuts. When the cuts are on the same straight line, there is a possibility that damage caused by the cuts will occur on the extension line of the cuts, and in particular, the closer the distance between the adjacent cuts is, the easier it is for the cracks to connect. Therefore, by increasing the distance between the cuts in the same straight line as much as possible, the connection of the cracks will be suppressed and the strength will be improved. Furthermore, when intermittent cuts are inserted in the same straight line and the distance between the cuts is close, the cuts become easily recognizable as intermittent straight line patterns after forming. On the other hand, by increasing the distance between the cuts, they are not recognizable as patterns, and the surface quality is excellent. In addition, the existence of cuts on the same straight line means that the angle between the straight line extending a certain cut and the straight line connecting the closest points of the aforementioned cut and the target cut is within 2 degrees.

Furthermore, the fiber length of all unidirectional prepregs can be adjusted to the aforementioned range, but it is not necessary to arrange the reinforcing fibers of the fiber length in all layers. The layers of unidirectional prepregs with adjusted fiber length can be appropriately selected and arranged according to the width, height, curvature and angle of the protrusion of the fiber-reinforced plastic. That is, for example, even if only the fiber length of the reinforcing fibers in the protrusion of the fiber-reinforced plastic and the reinforcing fibers in the layer directly below the protrusion in the plate-shaped portion is adjusted, a sufficient effect can still be obtained.

The fiber basis weight (FAW) of at least the plate-shaped portion of the fiber-reinforced plastic of the present invention can be 50 to 1,000 g/m ² as an example, but from the viewpoint of deformation resistance and fluidity, it is preferably 50 to 200 g/m ² , more preferably 70 to 200 g/m ² , and most preferably 70 to 120 g/m ² . In the case where the plate-shaped portion is composed of two or more layers, it is preferred that at least one layer is within the aforementioned range. In addition, in the case of a laminated structure with a high fiber basis weight, the number of laminated sheets can be reduced, but due to the small number of laminated sheets, the designed surface fibers will also flow to the protrusions, resulting in fiber confusion and poor appearance. On the other hand, in the case of a laminated structure with a low fiber basis weight, even if the molded product thickness is the same, the flow of the design surface fiber can be suppressed by increasing the number of laminated sheets, and a molded product with a high design appearance can be obtained.

The higher the fiber basis weight (FAW), the higher the rigidity of the fiber layer becomes. If it exceeds 1,000g/ ^m2 , the deformation resistance will increase, and it will be difficult for the fiber to flow into the inside of the protrusion (mold concave part), so it becomes easy to "unfilled" and "resin enriched". In addition, when the fiber of the high basis weight prepreg substrate is cut with a cutter, the fiber that escapes from the knife increases, and the fiber length outside the target range increases, and the possibility of becoming a prepreg substrate with low fluidity is high. Therefore, it is better to increase the number of low basis weight prepreg substrates and layer them from the perspective of formability. On the other hand, when the fiber basis weight (FAW) is less than 50g/ ^m2 , the cost will increase due to the increase in the production of the prepreg substrate and the number of layering procedures. Furthermore, from the perspective of reducing the number of lamination steps, it is more preferably 70 g/m ² or more.

When laminating two or more layers of unidirectional prepreg, unidirectional prepregs of two or more fiber basis weights may be used, and the lamination may be performed in any order. In other words, the interior of the plate-like portion may also have two or more unidirectional layers with different fiber basis weights. For example, in the case where the protrusion is only provided on the surface of one side, it is preferred to make the fiber basis weight of the outermost layer on the protrusion side smaller than that of at least one other unidirectional layer. In this way, by arranging a unidirectional prepreg of low fiber basis weight that is easy to flow on the protrusion side and molding it, and by arranging a unidirectional prepreg of high fiber basis weight that is difficult to flow on the design surface side and molding it, a molded product with small fiber deflection and high protrusion filling can be obtained. Furthermore, when the protrusions are on both sides of the plate-like portion, it is possible to take into account both the filling property of the protrusions and the number of stacking steps by setting the layer close to the protrusions to a low fiber basis weight and the middle layer to a high fiber basis weight.

The resin mass fraction (Rc) of the molded product (fiber reinforced plastic) of the present invention is preferably 10 to 70%. It is further preferably 20 to 60%. When the resin mass fraction (Rc) is less than 10%, the amount of resin on the surface of the molded product is small, so the surface of the molded product becomes uneven due to the unevenness of the fibers, and the fluidity of the fibers becomes lower, making it easy for "unfilling" to occur during molding. On the other hand, if the resin mass fraction (Rc) exceeds 70%, the resin becomes more, and excess resin portions ("resin enrichment") are generated in the concave parts of the molded product, etc., and the smoothness of the surface of the molded product is reduced due to the hardening and shrinkage of the resin.

In the present invention, the reinforcing fiber is not particularly limited, but glass fiber, aramid fiber, polyethylene fiber, silicon carbide fiber and carbon fiber are preferably used. In particular, glass fiber and carbon fiber are preferably used in order to obtain a fiber-reinforced composite material that is lightweight and high-performance and has excellent mechanical properties. In addition, glass fiber can be used alone, carbon fiber can be used alone, and from the perspective of the balance between performance and cost, both glass fiber and carbon fiber can be used at the same time.

Here, the glass fiber is not particularly limited, but E glass fiber, S glass fiber, C glass fiber, and D glass fiber are preferably used. From the viewpoint of the balance between cost and strength, E glass fiber is preferably used, S glass fiber is preferably used when high strength is required, C glass fiber is preferably used when acid resistance is required, and D glass fiber is preferably used when a low dielectric constant is required.

There is no particular limitation on the average fiber diameter of the glass fiber, but the average fiber diameter of the glass fiber is preferably 4 to 20 μm, and more preferably 5 to 16 μm. Generally, sufficient effects can be obtained if the average fiber diameter is 4 μm or more, while the strength tends to decrease if the average fiber diameter exceeds 20 μm.

In addition, it is preferable to pre-treat the glass fiber with a coupling agent such as an isocyanate compound, an organic silane compound, an organic titanium ester compound, an organic borane compound, and an epoxy compound in order to obtain a better mechanical strength.

The carbon fiber is not particularly limited, but polyacrylonitrile carbon fiber, rayon carbon fiber, asphalt carbon fiber, etc. are preferably used. Among them, polyacrylonitrile carbon fiber with high tensile strength is particularly suitable. As for the form of carbon fiber, twisted yarn, untwisted yarn, and non-twisted yarn can be used.

The carbon fiber preferably has a tensile modulus in the range of 180 to 600 GPa. If the tensile modulus is in this range, the obtained fiber-reinforced plastic can have rigidity, so the obtained molded product can be lightweight. In addition, generally speaking, the higher the elastic modulus of carbon fiber, the lower the strength tends to be, but if it is in this range, the strength of the carbon fiber itself can be maintained. A more preferred elastic modulus is in the range of 200 to 440 GPa, and a further preferred range is 220 to 300 GPa. It can also be a range formed by combining any of the above upper and lower limits. Here, the tensile modulus of carbon fiber is a value measured in accordance with JIS R7608-2007.

In addition, as for commercial products of carbon fibers, the following can be listed, but it is not particularly limited to these. Examples include: "TORAYCA (registered trademark)" T300, "TORAYCA (registered trademark)" T300B, "TORAYCA (registered trademark)" T400HB, "TORAYCA (registered trademark)" T700SC, "TORAYCA (registered trademark)" T800HB, "TORAYCA (registered trademark)" T800SC, "TORAYCA (registered trademark)" T830HB, "TORAYCA (registered trademark)" T1000G B. TORAYCA (registered trademark) T1100GC, TORAYCA (registered trademark) M35JB, TORAYCA (registered trademark) M40JB, TORAYCA (registered trademark) M46JB, TORAYCA (registered trademark) M55J, TORAYCA (registered trademark) M60JB, TORAYCA (registered trademark) M30SC (all manufactured by Toray Industries, Inc.), PX35 (manufactured by ZOLTEK Corporation), etc.

Furthermore, when the fiber-reinforced plastic of the present invention is used in a fabric as described below, the number of reinforcing fibers and carbon fibers constituting the fabric is not particularly limited, but from the perspective of manufacturing productivity, tensile/bending elastic modulus, strength, and design of the fiber-reinforced plastic required, the number of fibers is preferably in the range of 1,000 to 70,000, and more preferably 1,000 to 60,000. By aligning a plurality of fibers to form a complex yarn, flexibility can be obtained, and the yarn can be easily deformed into any shape during molding. In addition, in multifilaments, other fibers can make up for the shortcomings of one fiber, so the variation of the mechanical properties of the molded product is suppressed and stable performance can be obtained.

Next, the matrix resin in combination with the aforementioned reinforcing fiber constituting the fiber-reinforced plastic of the present invention is described. In the matrix resin, a thermosetting resin or a thermoplastic resin is preferably used as a main component.

Here, the thermosetting resin as the main component of the base resin may be a resin that self-hardens due to heat, or may contain a hardener, a hardening accelerator, etc. Preferably, it is a resin that causes a crosslinking reaction due to heat to form at least a partial three-dimensional crosslinking structure, but it is not particularly limited. As examples of thermosetting resins, preferably from the viewpoint of handling properties are epoxy resin compositions, vinyl ester resin compositions, unsaturated polyester resin compositions, polyurethane resin compositions, benzophenone resin compositions, phenolic resins, urea resin compositions, melamine resin compositions, and polyimide resin compositions. Among them, from the perspective of the performance and environmental resistance of the fiber-reinforced plastic, epoxy resin compositions, vinyl ester resin compositions, and unsaturated polyester resin compositions are more preferred. Furthermore, the thermosetting resin composition containing these does not need to be a single type, and the resin compositions may be mixed with each other.

Furthermore, the thermoplastic resin may be dispersed in the thermosetting resin in the form of particles or fibers, or the thermoplastic resin may be dissolved in the thermosetting resin for blending to prepare the matrix resin composition. The thermoplastic resin used in this manner is preferably a thermoplastic resin having a bond selected from carbon-carbon bonds, amide bonds, imide bonds, ester bonds, ether bonds, carbonate bonds, urethane bonds, sulfide bonds, sulfide bonds, and carbonyl bonds, but may partially have a cross-linked structure.

On the other hand, the thermoplastic resin as the main component of the base resin is not particularly limited, but from the viewpoint of easy processing, mechanical properties, and design, it is preferable to use polymethyl methacrylate (PBSMMA) resin, polyurethane (TPU) resin, polyethylene terephthalate (PET) resin, polybutylene terephthalate (PBT) resin, acrylonitrile butadiene styrene (ABS) resin, polyamide (PA) resin (especially PA6, PA66, PA12), polycarbonate (PC) resin, and PC/ABS resin obtained by blending polycarbonate (PC) and acrylonitrile butadiene styrene (ABS) resin.

Here, when coloring is required as one of the design properties of the fiber-reinforced plastic, the color is not particularly limited, but the design property can be improved by coloring the thermoplastic resins listed above with black, red, yellow, green, blue, purple, brown, etc.

In the present invention, in order to make at least one layer other than the outermost layer having the protrusions as a non-unidirectional layer, a non-unidirectional reinforcing fiber sheet in which reinforcing fibers are oriented in at least two directions can be used together with the unidirectional prepreg.

As for the reinforcing fibers constituting the non-unidirectional reinforced fiber sheet, the above-mentioned ones can be used, but it is preferred that at least a part of the reinforcing fibers contain fibers other than thermoplastic resin fibers. When manufacturing the fiber-reinforced plastic of the present invention, it is heated and press-formed, but thermoplastic resin fibers become soft due to heat. Therefore, by making at least a part of the reinforcing fibers constituting the non-unidirectional reinforced fiber sheet be fibers other than thermoplastic resin fibers, it is possible to suppress the variation in thickness and shape of the molded product.

As for the form of the non-unidirectional reinforced fiber sheet, for example, it is more appropriate to use a fabric. Specifically, when the fiber-reinforced plastic of the present invention has a protrusion only on one side of the plate-like portion, it is better to configure a fabric as the reinforcing fiber forming the outermost surface of the opposite side. The fabric woven with warp yarn and weft yarn not only has excellent mechanical properties and durability of form, but can also be used to improve the design by showing the texture of the fabric. In addition, the fibers constituting this fabric can use the same reinforcing fibers as other layers, but it is also possible to use different fibers.

The weave and density of the fabric are not particularly limited and can be arbitrarily selected from the viewpoint of the design of the fiber reinforced plastic. As examples of the weave, plain weave, twill weave, satin weave, ridge weave, basket weave, nest weave, embossed weave, imitation weave, and pear weave are preferably used. As for the twill texture, there can be exemplified three-layer twill, four-layer twill, five-layer twill, six-layer twill, elongated twill, bent twill, ruptured twill, skipped twill, mountain shaped twill, mesh twill, overlapped twill, twisted twill, day and night twill, decorative twill, and gradient twill. In terms of satin texture, examples include five-layer satin, seven-layer satin, eight-layer satin, ten-layer satin, variable satin, wide satin, overlapping satin, granite satin, day and night satin, and gradient satin. In terms of ridge texture, examples include meridian ridge texture, latitudinal ridge texture, and variable ridge texture. In terms of basket weave, examples include: regular basket weave, variable basket weave, irregular basket weave, relative basket weave, triaxial fabric formed by weaving fibers in three directions, etc.

As for the reinforcing fibers constituting the fabric, it can be a single glass fiber as exemplified above, or a single carbon fiber, or a combination of different glass fibers and carbon fibers. It is also possible to further combine single or multiple other different reinforcing fibers. In addition, from the perspective of performance/cost/design excellence, at least one glass fiber and at least one carbon fiber can be mixed and interwoven.

In addition, the fabric of the outermost layer opposite to the surface where the protrusion is formed is preferably impregnated with a base resin in advance. In addition, the base resin impregnated in the fabric is preferably the same as the base resin of the other layers, but a different resin can also be used. However, when a resin different from the resin of the other layers is used, it is preferred to confirm the compatibility and adhesion, and insert a bonding film as needed.

The fiber basis weight of the fabric is preferably 10 to 300 g/m ² , and more preferably 30 to 150 g/m ² . When the fiber basis weight of the fabric is 10 g/m ² or more, the plastic flow of the fibers due to the pressure generated during press forming can be suppressed, and the appearance defects such as fiber meandering of the fabric fibers used on the surface layer and resin enrichment on the design surface can be suppressed. In addition, when the fiber basis weight of the fabric is 300 g/m ² or less, the fabric is soft and has excellent formability. When the epoxy resin composition is impregnated during forming, the resin easily reaches the center of the thickness direction, and the unimpregnated part (void) becomes difficult to remain. The result is a fiber-reinforced plastic that exhibits excellent mechanical properties such as compressive strength.

The basis weight of the prepreg formed by impregnating the fabric with the matrix resin is preferably 20 to 400 g/m ² , and more preferably 40 to 300 g/m ² when glass fiber or carbon fiber is used as the reinforcing fiber. When the basis weight is 20 g/m ² or more, the weaving property becomes good, and when the basis weight is 400 g/m ² or less, the fabric becomes soft and easy to shape, and when the matrix resin (e.g., epoxy resin composition, etc.) is impregnated during the manufacture and molding of the prepreg, the resin easily reaches the center portion in the thickness direction, and the unimpregnated portion (void) becomes less likely to remain. The result is a fiber-reinforced plastic that exhibits excellent mechanical properties such as compressive strength.

In addition, as for the form of the non-unidirectional reinforced fiber sheet, a non-woven fabric of the above-mentioned reinforcing fiber (glass, carbon fiber, etc.) can also be preferably used. The non-woven fabric is preferably used, for example, inside a plate-shaped part that does not require design.

The structure and manufacturing method of the nonwoven fabric are not particularly limited, but nonwoven fabrics manufactured by dry methods such as a carding method in which short fibers of several centimeters are opened to form a thin web using a carding machine, and an air-laid method in which the opened short fibers are dispersed using a pneumatic random disperser to form a web on a belt conveyor can be preferably used. In addition, in the case of nonwoven fabrics manufactured by dry methods, fibers are wound by needle-punching to improve the morphological stability of the web physically, and binder resins such as unsaturated polyester, polyvinyl alcohol (PVA), and copolymers thereof are applied by spraying or impregnation to fix the fibers to each other and improve the morphological stability of the web chemically. As for the method of fixing the fibers, there are the following methods: mixing the fibers of the thermoplastic resin when manufacturing the web, and attaching the thermoplastic resin particles to the web and then putting the web into a hot roll or oven to melt the thermoplastic resin and fix the fibers to each other.

As for other examples of nonwoven fabrics, it is also possible to preferably use a nonwoven fabric produced by a wet method in which short fibers are dispersed in water and scooped onto a papermaking net. In addition, in order to improve the dimensional stability and handling properties of the nonwoven fabric produced by the wet method in the same manner as the nonwoven fabric produced by the dry method, it is also preferred to apply a binder resin such as unsaturated polyester, polyvinyl alcohol (PVA), or a copolymer thereof by spraying or impregnation to chemically fix the fibers to each other, or to blend fibers of a thermoplastic resin during net manufacturing, or to attach thermoplastic resin particles to the net, and then put the net into a hot roll or oven to melt the thermoplastic resin and fix the fibers to each other.

As for non-woven fabrics other than the above, from the perspective of excellent mechanical properties and low price, they can also be preferably used: non-woven fabrics made by the filament bonding method of layering yarns obtained by melt-spinning thermoplastic resin on a belt conveyor; non-woven fabrics made by the melt-blowing method of blowing air on the melt-spun filaments to form fine fibers, accumulating the fibers on a net, and netting.

The basis weight of the nonwoven fabric is preferably 10 to 300 g/m ² . In order to absorb the deformation of the prepreg during molding and mitigate the impact on the surface of the molded product, thickness and strength are required. However, if it is too thick, there is a possibility of affecting the physical properties of the molded product. Therefore, it is more preferably 30 to 150 g/m ² , and the most preferably 40 to 100 g/m ² . However, it is also possible to adjust the basis weight to the above range by stacking nonwoven fabrics with a low basis weight.

When the non-unidirectional reinforced fiber sheet is provided on the surface of the plate-shaped portion, the thickness is preferably 0.01 to 1.0 mm, more preferably 0.05 to 0.5 mm. When the thickness of the non-unidirectional reinforced fiber sheet is 0.01 mm or more, the plastic flow of the fiber caused by the pressure generated during the press forming can be suppressed, and the winding of the fabric fiber used on the surface of the plate-shaped portion and the resin enrichment in the design surface can be suppressed. On the other hand, when the thickness of the non-unidirectional reinforced fiber sheet is 1.0 mm or less, it is soft and has excellent formability. At the same time, when the epoxy resin composition is impregnated during molding, the resin easily reaches the center of the thickness direction, and the unimpregnated part (void) becomes difficult to remain, resulting in a fiber-reinforced plastic showing excellent mechanical properties such as compressive strength.

However, when a non-woven fabric is used as the non-unidirectional reinforcing fiber sheet, it is possible to adjust the thickness of the non-woven fabric by the pressure during press molding, so a non-woven fabric with a thickness of 0.01 to 3.0 mm can be preferably used.

Next, the manufacturing method of the fiber-reinforced plastic of the present invention is described in detail, but the present invention is not limited thereto.

The fiber-reinforced plastic of the present invention can be obtained by, for example, making a unidirectional prepreg formed by impregnating a base resin into a plurality of reinforcing fibers, laminating it with the same or different types of unidirectional prepregs, fiber substrates, etc. as needed, and integrating the laminated body by heating and pressurizing it as needed by press molding, high-pressure autoclave molding, oven molding, or vacuum oven molding.

As for the molding method, various molding methods can be listed as above, and there is no particular limitation, but it is preferable to use a press molding method in which a unidirectional prepreg prepared by impregnating a matrix resin is layered and shaped as needed, put into a mold, and molded by heating and pressing with a press machine. In press molding, by molding with high pressure, the reinforcing fiber and the matrix resin are integrated, and the influence of fiber relaxation and angle variation can be reduced.

The cavity (gap) of the mold used for press molding will form the shape of the desired fiber reinforced plastic in the end, and the shape of the mold corresponding to the protrusion of the fiber reinforced plastic will become the concave part. In press molding, when heat molding is performed, it is possible to make the reinforcing fiber and the matrix resin flow to the concave part and form the shape of the fiber reinforced plastic. Therefore, it is not necessary to shape the unidirectional prepreg into the same shape as the fiber reinforced plastic in advance. Therefore, it is better to reduce the process of preform production.

Compared with other molding methods, the press molding method is simpler in terms of pre-molding preparation and post-molding processing, so the productivity is overwhelmingly superior. Furthermore, when the base resin is a thermoplastic resin, the fiber-reinforced plastic needs to be removed after the mold is cooled, but when the base resin is a thermosetting resin, even when the mold is at a high temperature, it is possible to demold the molded fiber-reinforced plastic while keeping the mold temperature substantially constant. Therefore, the mold cooling step required when the base resin is a thermoplastic resin is not required, so as long as it is combined with a fast-hardening thermosetting resin (fast-hardening resin), the molding cycle can be shortened and high productivity can be achieved.

In addition, it is preferred that the mold temperature T (°C) of the press molding and the exothermic peak temperature Tp (°C) obtained by differential scanning calorimetry (DSC) of the thermosetting resin satisfy the following relationship (I). It is further preferred that the following relationship (II) is satisfied.

Tp-60≦T≦Tp+20        ． ． ． (I) Tp-30≦T≦Tp            ． ． ． (II) When the mold temperature T(℃) is lower than Tp-60(℃), the time required for the resin to harden becomes very long, and there is also the possibility of insufficient hardening. On the other hand, when it is higher than Tp+20(℃), the rapid reaction of the resin may cause the formation of voids inside the resin and poor hardening. In addition, the exothermic peak temperature Tp(℃) obtained by DSC is the value measured under the condition of a heating rate of 10℃/min.

The fiber-reinforced plastic of the present invention is preferably manufactured under the condition that the minimum viscosity obtained by the dynamic viscoelastic measurement (DMA) of the thermosetting resin used as the base resin is 0.1 to 100 Pa. s. It is further preferably 0.5 to 10 Pa. s. When the minimum viscosity is less than 0.1 Pa. s, there is a situation that only the resin will flow when pressurized, and the reinforcing fiber is not fully filled to the front end of the protrusion. On the other hand, when it is greater than 100 Pa. s, there is a situation that the resin lacks fluidity, so the reinforcing fiber and the resin are not fully filled to the front end of the protrusion. In addition, the minimum viscosity obtained by DMA is a value measured under the condition of a temperature increase rate of 1.5°C/minute.

Furthermore, in the present invention, it is preferred to first make a unidirectional prepreg formed by impregnating a base resin with a plurality of reinforcing fibers, and then laminate them together with the same or different types of unidirectional prepregs, non-unidirectional reinforced fiber sheets, or other fiber substrates as needed to form a preform, and place the preform in a preheated mold (e.g., a concave mold), close the mold and apply pressurization, thereby obtaining a fiber-reinforced plastic having a plate-like portion and at least one protrusion protruding from at least one side of the plate-like portion. However, at this time, it is preferred that all directions in which the protrusions extend are not parallel or perpendicular to (are not parallel or perpendicular to) the fiber orientation direction of any unidirectional prepreg in the preform.

When a unidirectional prepreg is combined with other unidirectional prepregs, a non-unidirectional reinforced fiber sheet, or a fiber substrate as described above, it is also preferred that the non-unidirectional reinforced fiber sheet be arranged in at least one layer of the layer after the second layer from the surface of the preform (i.e., a layer other than the outermost layer on the side where the protrusion is provided).

In particular, when a protrusion is provided only on one side of the plate-like portion and a non-unidirectional reinforced fiber sheet in a fabric form is arranged on the outermost surface on the side opposite to the surface on which the protrusion is provided, the plastic flow of the fibers caused by the pressure during press forming can be suppressed, and the fiber meandering of the fabric fibers used in the surface layer, the resin enrichment on the design surface, and other appearance defects can be suppressed.

The non-unidirectional reinforced fiber sheet may be a dry sheet without a matrix resin, or a pre-preg sheet in which a matrix resin is impregnated in at least a portion of the area in advance.

When the non-unidirectional fiber-reinforced sheet is a prepreg-shaped sheet, the matrix resin impregnated in advance in the non-unidirectional fiber-reinforced sheet is preferably the same resin as the other prepregs, but from the viewpoint of adhesion and formability, a better one can be arbitrarily selected.

Furthermore, when the non-unidirectional fiber-reinforced sheet is a prepreg-shaped sheet, the fiber volume content Vf〔a〕 of the non-unidirectional reinforced fiber sheet and the fiber volume content Vf〔b〕 of the aforementioned unidirectional prepreg are preferably in the relationship of Vf〔a〕＞Vf〔b〕. In this case, during press molding, a space is generated for the matrix resin contained in the unidirectional prepreg to be impregnated in the non-unidirectional reinforced fiber sheet. That is, by the pressure during press molding, the resin contained in the unidirectional prepreg is impregnated in the portion of the non-unidirectional reinforced fiber sheet that is not impregnated with the resin, so that a molded product that is fully filled with the resin can be obtained, for example, a fiber-reinforced plastic with excellent mechanical properties and a porosity of less than 2% can be obtained.

Furthermore, Vf〔a〕is preferably 55 to 99.9%, and more preferably 80 to 99%. When Vf〔a〕is 55% or more, it is difficult to be affected by the resin flow caused by the pressure during press molding, and the fiber flow can be suppressed, so that a fiber-reinforced plastic with less fiber disorder and less surface unevenness and excellent appearance quality can be obtained. [Example]

Next, the present invention is further described using embodiments and comparative examples, but the present invention is not particularly limited thereto.

<Evaluation of the filling properties of protrusions with fibers and resins> [1] Observation of the appearance of protrusions By visual inspection, check whether there are "unfilled" protrusions where neither fibers nor resins are filled, or "resin-rich" protrusions where only resins are filled.

[2] Cross-sectional observation of the protrusion All protrusions were cut using a disc grinder to include the plate-shaped portion. After the cut surface was polished, the inside of the protrusion was observed using a microscope (VHX-6000 manufactured by Keyence Co., Ltd.) to confirm the state of the carbon fibers filled inside.

In the above [1], the carbon fibers were filled to the tip of the ridge without "unfilled" and "resin enriched", and the carbon fibers filled in the protrusions were connected to the continuous fibers in the plate-like part (i.e., no "resin enriched") were rated as "A", and in the above [1], the carbon fibers were filled to the tip of the ridge without "unfilled" and "resin enriched", and the carbon fibers filled in the protrusions were connected to the continuous fibers in the plate-like part, but a part of the inside thereof had slight resin accumulation (less than 10% of the cross-sectional area of the ridge) was rated as "B" in the table, and the rest were rated as "F".

<Evaluation of warp of molded products> Place the plate-shaped part on a flat inspection table (table) so that the protrusion is facing upward, and check the gap (lift) between the end of the plate-shaped part and the inspection table. The plate-shaped part is in contact with the inspection table almost entirely, and the lift at the four corners is rated "A ⁺ " if it is less than 0.7 mm, "A" if it is more than 0.7 mm and less than 1 mm, and "F" if it is more than 1 mm.

<Appearance inspection of the design surface of the molded product> Hold the upper part of the plate with your hand so that the protrusion is facing downward, and visually observe the surface (design surface) opposite to the surface with the protrusion under a fluorescent light in an environment with an illumination of 1200lx (lux).

At this time, the molded product was rotated 360° in the horizontal direction, and then observed while tilting at an angle of 0° to 60° in the vertical direction to check whether the reflected light of the fluorescent lamp along the ridges was deformed. The ones without deformation at any angle were rated "A", those with deformation only at a certain angle were rated "B", and those with deformation at all angles were rated "F".

Furthermore, in the surface layer opposite to the surface with the protrusion, for the fabric using the reinforced fiber, the fiber width was checked. If the fiber width just below the protrusion was 90% or more of the fiber width used, it was rated as "A ⁺⁺ ", if it was 80% or more and less than 90%, it was rated as "A ⁺ ", if it was 75% or more and less than 80%, it was rated as "A", and if it was less than 75%, it was rated as "F".

On the other hand, for those using unidirectional prepreg in the surface layer opposite to the surface with the protrusion, skew was confirmed. Regarding the skew of the fiber located directly below the protrusion, the plane of the fiber-reinforced plastic was visually confirmed, and those with a height of skew 402 of 0.3 mm or less as shown in Figure 8 (B) were rated as "A ⁺⁺ ", those exceeding 0.3 mm and 0.6 mm or less were rated as "A ⁺ ", those exceeding 0.6 mm and 1.0 mm or less were rated as "A", and those exceeding 1.0 mm were rated as "F". In addition, in Figure 8, (A) shows a general surface state without skew of the reinforcing fiber, and (B) shows a surface state with skew.

[Example 1] Twelve prepreg substrates each having a size of 100 mm × 100 mm were cut out from unidirectional prepreg #P384-S-7 (carbon fiber (4,900 MPa, tensile modulus 235 GPa), FAW = 70 g/m ² , thermosetting epoxy resin, Rc = 40%) manufactured by Toray Industries, Inc. These were stacked in a [30/60] ₆ pattern to prepare a prepreg substrate laminate.

Next, prepare a 100mm×100mm concave mold as the lower mold, and prepare a convex mold with a groove for forming a protrusion (ribbed stripe) in the central part of the 100mm×100mm convex part (ribbed stripe groove, width 1.0mm, length from the intersection of the ribbed stripes to the three front ends is 40mm, and depth is 3mm in a Y shape (assuming the ribbed stripe formation of Figure 11)) as the upper mold, and heat them to 150°C.

The prepreg substrate laminate prepared in advance is accommodated in the lower mold in such a manner that the 0° direction of FIG. 11 is aligned with the 0° direction of the above-mentioned prepreg substrate laminate. After the upper mold is installed on the lower mold, a heating type press molding machine is used to perform molding and heat curing of the matrix resin under the conditions of a pressure of 12 MPa, a heating temperature of 150°C, and a pressurizing time of 3 minutes to obtain a fiber-reinforced plastic with convex strips.

The obtained fiber-reinforced plastic had a Y-shaped ridge in the center of a plate-like portion with a width of 100 mm, a length of 100 mm, and a thickness of 0.7 mm. The evaluation was performed using the method described in the above-mentioned <Evaluation of the Filling Property of Fibers and Resins into the Protrusion>. The results showed that [1] carbon fibers were found to be filled to the tip of each ridge in the external observation of the protrusion. [2] In the cross-sectional observation of the protrusion, a slight accumulation of resin ("resin enrichment") was observed inside the protrusion, but it was also possible to confirm that the carbon fibers connected to the plate-like portion were filled to the inside of each ridge, resulting in a B evaluation.

Furthermore, the evaluation was performed by the method described in the above-mentioned <Evaluation of warp of molded product>, and the result was A ⁺ evaluation (almost the entire surface was in contact with the inspection table, and the floating of the four corners was 0.4 mm or more and less than 0.7 mm).

Inspection was performed using the method described in the above <Appearance inspection of the design surface of molded products>. As for deformation, only the reflected light of the fluorescent lamp at a certain fixed angle was deformed, which was rated B. As for skewness, it was more than 0.6mm and less than 1.0mm, which was rated A.

[Example 2] Using the cut pattern of FIG. 7, a roller cutter with a knife arranged on a cylinder was pushed onto a unidirectional prepreg #P384-S-7 manufactured by Toray Industries, Inc., in such a manner that the fiber length was 13 mm, the cut width Ws = 0.25 mm, and the cut angle θ = ±14°, and a cut was inserted into the reinforcing fiber of the prepreg to obtain a prepreg with the cut inserted.

Eight prepreg base materials each having a size of 100 mm×100 mm were cut out from the prepreg into which the cutouts were inserted, and these were layered so as to have a ratio of [+40/-50/+40/-50] _s to prepare a prepreg base material layered body.

Next, prepare a 100mm×100mm concave mold as the lower mold, and prepare a convex mold with a groove for forming a protrusion (ribbed stripe) in the central part of the 100mm×100mm convex part (ribbed stripe groove, width 1.0mm, length from the intersection of the ribbed stripes to the four front ends is 40mm, and depth is 3mm in an X shape (assuming the ribbed stripe formation of Figure 12)) as the upper mold, and heat to 150°C.

The prepreg substrate laminate prepared in advance is accommodated in the lower mold in such a manner that the protrusion a in Figure 12 is set to 0°. After the upper mold is installed on the lower mold, the molding and heat-hardening of the matrix resin are carried out by a heating type press molding machine under the conditions of a pressure of 12 MPa, a heating temperature of 150°C, and a pressing time of 3 minutes to obtain a fiber-reinforced plastic with convex strips.

The obtained fiber-reinforced plastic had an X-shaped ridge in the center of a plate-like portion with a width of 100 mm, a length of 100 mm, and a thickness of 0.7 mm. Various evaluations were performed in the same manner as in Example 1. As a result, [1] the carbon fibers were confirmed to be filled to the tip of each ridge in the external observation of the ridge. In addition, [2] the cross-sectional observation of the ridge also confirmed that the carbon fibers connected to the plate-like portion were filled to the inside of each ridge, and the ridge filling property was evaluated as A.

The warping of the plate-shaped part is rated A ⁺ (almost the entire surface is in contact with the inspection table, and the floating of the four corners is 0.4mm or more and less than 0.7mm).

Regarding the appearance inspection of the design surface of the molded product, when observing under a fluorescent light, if there is deformation only at a certain fixed angle of the reflected light of the fluorescent light, it is evaluated as B. Next, regarding the skewness, if it exceeds 0.3mm and is less than 0.6mm, it is evaluated as A ⁺ .

[Example 3] The same procedure as in Example 2 was followed to prepare a prepreg substrate laminate.

Next, the same mold as in Example 2 was prepared and heated to 150°C. Then, the concave mold surface was set as the design surface, and a Toray (stock) fabric prepreg (#CO6343B carbon fiber tensile strength 3530MPa, tensile elastic modulus 230GPa, basis weight 198g/ ^m2 ) was placed as the design surface substrate, and a glass felt (basis weight 90g/ ^m2 ) without impregnation resin was placed thereon, and the above-prepared prepreg substrate laminate was further placed thereon.

The molding conditions are set to be the same as those in Example 2 and the molding is carried out, thereby obtaining a fiber-reinforced plastic having X-shaped ridges.

Various evaluations were performed in the same manner as in Example 1. As a result, [1] the external observation of the protrusion confirmed that the carbon fibers were filled to the tip of each ridge. In addition, [2] the cross-sectional observation of the protrusion confirmed that the carbon fibers connected to the plate-like portion were filled to the inside of each ridge, and the ridge filling property was evaluated as A.

The warping of the plate-shaped part is rated A ⁺ (almost the entire surface is in contact with the inspection table, and the floating of the four corners is 0.4mm or more and less than 0.7mm).

Regarding the appearance inspection of the design surface of the molded product, when observed under a fluorescent light, it can be confirmed that the molded product has no deformation at any specified angle, and is rated A. The fiber width of the fabric is also 90% or more, and is rated A ⁺⁺ . It is believed that by inserting the glass felt without impregnation resin between the two surface layers, the glass felt can mitigate the plastic flow caused by the pressure applied during the press molding, and will not be affected by the prepreg layer flowing to the insertion cut of the ridge, and the shape of the fabric prepreg constituting the design surface can be maintained, so that a fiber-reinforced plastic with a better appearance than Example 2 can be obtained.

[Example 4] A fiber-reinforced plastic was obtained by molding in the same manner as in Example 3 except that CF paper (basis weight 48 g/m ² ) not impregnated with resin was inserted in place of glass felt on the upper layer of the fabric prepreg on the design surface.

Various evaluations were performed in the same manner as in Example 1. As a result, [1] the external observation of the protrusion confirmed that the carbon fibers were filled to the tip of each ridge. In addition, [2] the cross-sectional observation of the protrusion confirmed that the carbon fibers connected to the plate-like portion were filled to the inside of each ridge, and the ridge filling property was evaluated as A.

The warping of the plate-shaped part is rated A ⁺ (almost the entire surface is in contact with the inspection table, and the floating of the four corners is 0.4mm or more and less than 0.7mm).

Regarding the appearance inspection of the design surface of the molded product, when observed under a fluorescent light, it can be confirmed that the molded product has no deformation at any specified angle, and is rated A. Regarding the fiber width of the fabric, it is also rated A ⁺⁺ because it is more than 90%. It is believed that by inserting CF paper without impregnation resin between the two surface layers in the same way as in Example 3, the plastic flow caused by the pressure applied during the press molding can be mitigated by the CF paper, and the prepreg layer flowing to the insertion cut of the rib will not be affected, and the shape of the fabric prepreg constituting the design surface can be maintained, so that a fiber-reinforced plastic with a better appearance than Example 2 can be obtained.

[Example 5] In the upper layer of the fabric prepreg on the design surface, a fabric prepreg identical to the fabric prepreg on the design surface is inserted as a resin impregnated sheet instead of glass felt, and except for this, the same method as Example 3 (i.e., two layers of fabric prepreg are inserted on the design surface side) is used for molding, thereby obtaining a fiber-reinforced plastic.

Various evaluations were performed in the same manner as in Example 1. As a result, [1] the external observation of the protrusion confirmed that the carbon fibers were filled to the tip of each ridge. In addition, [2] the cross-sectional observation of the protrusion confirmed that the carbon fibers connected to the plate-like portion were filled to the inside of each ridge, and the ridge filling property was evaluated as A.

The warping of the plate-shaped part is rated A ⁺ (the warping of the four corners is 0.4mm or more and less than 0.7mm when almost the entire surface of the inspection table is in contact).

Regarding the appearance inspection of the design surface of the molded product, when observed under a fluorescent light, it can be visually deformed only at a certain fixed angle, which is rated B. Regarding the fiber width of the fabric, it is rated A ⁺⁺ for more than 90%. By overlapping two pieces of fabric prepreg, the plastic flow caused by the pressure applied during press molding can be mitigated by the inner fabric prepreg, and the prepreg layer flowing to the insertion cut of the rib will not be affected. The shape of the fabric prepreg constituting the design surface can be maintained, and a fiber-reinforced plastic with a better appearance than Example 2 can be obtained.

[Example 6] The FAW of the prepreg with a cutout used in Example 2 was set to 100 g/m ² , and six prepreg substrates with a size of 100 mm×100 mm were cut out from the prepreg with a cutout. These were layered so as to have a thickness of [+40/-50] _3. Except for these aspects, the same method as in Example 2 was used to obtain a fiber-reinforced plastic having ridges and the same molded product thickness as in Example 2.

Various evaluations were performed in the same manner as in Example 1. As a result, [1] the external observation of the protrusion confirmed that the carbon fibers were filled to the tip of each ridge. In addition, [2] the cross-sectional observation of the protrusion confirmed that the carbon fibers connected to the plate-like portion were filled to the inside of each ridge, and the ridge filling property was evaluated as A.

The warping of the plate-shaped part is rated A ⁺ (the warping of the four corners is 0.4mm or more and less than 0.7mm when almost the entire surface of the inspection table is in contact).

Regarding the appearance inspection of the design surface of the molded product, when observed under a fluorescent light, the deformation can be visually observed only at a certain fixed angle, which is evaluated as B. Next, regarding the skewness, it is evaluated as A if it exceeds 0.6 mm and is less than 1.0 mm. Compared with Example 2, the evaluation of skewness is lower, but it is believed that this is because the base material on the design surface side is also somewhat affected by the fiber flow of the protrusion due to the reduction in the number of layers.

[Example 7] The FAW of the prepreg with a cutout used in Example 2 was set to 120 g/m ² , and five prepreg substrates with a size of 100 mm×100 mm were cut out from the prepreg with a cutout. These were layered in a manner of [45/-50/45/-50/45]. Except for these aspects, the same method as in Example 2 was used to obtain a fiber-reinforced plastic having ridges and the same molded product thickness as in Example 2.

Various evaluations were performed in the same manner as in Example 1. As a result, [1] the external observation of the protrusion confirmed that the carbon fibers were filled to the tip of each ridge. In addition, [2] the cross-sectional observation of the protrusion confirmed that the carbon fibers connected to the plate-like portion were filled to the inside of each ridge, and the ridge filling property was evaluated as A.

The warping of the plate-shaped part is rated A ⁺ (the warping of the four corners is 0.4mm or more and less than 0.7mm when almost the entire surface of the inspection table is in contact).

Regarding the appearance inspection of the design surface of the molded product, when observed under a fluorescent light, the deformation can be visually observed only at a certain fixed angle, which is evaluated as B. Next, regarding the skewness, it is evaluated as A if it exceeds 0.6 mm and is less than 1.0 mm. Compared with Example 2, the evaluation of skewness is lower, but it is believed that this is because the base material on the design surface side is also somewhat affected by the fiber flow of the protrusion due to the reduction in the number of layers.

[Example 8] The slitted prepreg used in Example 2 was set to FAW = 100 g/m ² , and four prepreg substrates of 100 mm×100 mm were cut out. These were layered to obtain [0/90] _s . A prepreg substrate layered body was prepared.

Next, prepare a 100mm×100mm concave mold as the lower mold, and prepare a convex mold with a groove for forming a protrusion (ribbed stripe) in the central part of the 100mm×100mm convex part (ribbed stripe groove, width 1.5mm, ribbed stripe length 40mm, depth 5mm in an eight-shaped shape (assuming the ribbed stripe formation of Figure 15)) as the upper mold, and heat them to 150°C. Then, the concave mold surface is set as the design surface, and the same fabric prepreg as in Example 3 is arranged as the design surface substrate. On the upper layer, the prepreg substrate laminate prepared in advance is accommodated in the lower mold in a manner that sets the line shown in Figure 15 to 0°. After the upper mold is installed on the lower mold, a heating type press molding machine is used to perform molding and heat curing of the matrix resin under the conditions of a pressure of 12 MPa, a heating temperature of 150°C, and a pressurizing time of 3 minutes to obtain a fiber-reinforced plastic with convex strips.

The obtained fiber-reinforced plastic has an eight-shaped convex strip in the center of a plate-shaped portion having a width of 100 mm, a length of 100 mm, and a thickness of 0.7 mm.

Various evaluations were performed in the same manner as in Example 1. As a result, [1] the external observation of the protrusion confirmed that the carbon fibers were filled to the tip of each ridge. In addition, [2] the cross-sectional observation of the protrusion confirmed that the carbon fibers connected to the plate-like portion were filled to the inside of each ridge, and the ridge filling property was evaluated as A.

The warping of the plate-shaped part is rated A ⁺ (the warping of the four corners is 0.4mm or more and less than 0.7mm when almost the entire surface of the inspection table is in contact).

Regarding the appearance inspection of the design surface of the molded product, when observing under a fluorescent light, if the deformation can be visually observed only at a certain fixed angle, it is rated B. Regarding the fiber width of the fabric, if it is more than 75% and less than 80%, it is rated A.

[Example 9] The notched prepreg used in Example 2 was set to FAW = 100 g/m ² , and four prepreg substrates of 100 mm × 100 mm were cut out from the notched prepreg. These were layered to have a thickness of [+40/-50] _s . A prepreg substrate layered body was prepared.

Next, prepare a 100mm×100mm concave mold as the lower mold, and prepare a convex mold with a groove for forming a protrusion (rib) in the central part of the 100mm×100mm convex part (rib groove, width 1.5mm, length from the intersection of protrusion a and protrusions b, c in Figure 13 to the two front ends of each of the protrusions b, c is 40mm, and depth is 5mm in H shape (assuming the rib of Figure 13 is formed)) as the upper mold, and heat to 150°C. Then, the concave mold surface is set as the design surface, and the same fabric prepreg as in Example 3 is arranged as the design surface substrate. On the upper layer, the prepreg volume layer prepared in advance is accommodated in the lower mold in such a manner that the protrusion a in Figure 13 is set to 0°. After the upper mold is installed on the lower mold, a heating type press molding machine is used to perform molding and heat curing of the matrix resin under the conditions of a pressure of 12 MPa, a heating temperature of 150°C, and a pressurizing time of 3 minutes to obtain a fiber-reinforced plastic with convex strips.

The obtained fiber-reinforced plastic has an H-shaped convex strip in the center of a plate-shaped portion having a width of 100 mm, a length of 100 mm, and a thickness of 0.7 mm.

Various evaluations were performed in the same manner as in Example 1. As a result, [1] the external observation of the protrusion confirmed that the carbon fibers were filled to the tip of each ridge. In addition, [2] the cross-sectional observation of the protrusion confirmed that the carbon fibers connected to the plate-like portion were filled to the inside of each ridge, and the ridge filling property was evaluated as A.

The warping of the plate-shaped part is rated A ⁺ (the warping of the four corners is 0.4mm or more and less than 0.7mm when almost the entire surface of the inspection table is in contact).

Regarding the appearance inspection of the design surface of the molded product, when observing under a fluorescent light, if the deformation can be visually observed only at a certain fixed angle, it is rated B. Regarding the fiber width of the fabric, if it is more than 75% and less than 80%, it is rated A.

[Example 10] Six prepreg substrates each having a size of 100 mm × 100 mm were cut out from the cut-out prepreg used in Example 5. The prepreg substrate laminate was prepared by laminating them in a manner of [+40/-50] ₃ , and a fiber-reinforced plastic was obtained in the same manner as in Example 5 except that a fabric prepreg as a resin-impregnated sheet was not used.

Various evaluations were performed in the same manner as in Example 1. As a result, [1] the external observation of the protrusion confirmed that the carbon fibers were filled to the tip of each ridge. In addition, [2] the cross-sectional observation of the protrusion confirmed that the carbon fibers connected to the plate-like portion were filled to the inside of each ridge, and the ridge filling property was evaluated as A.

The warping of the plate-shaped part is rated A ⁺ (the warping of the four corners is 0.4mm or more and less than 0.7mm when almost the entire surface of the inspection table is in contact).

Regarding the appearance inspection of the design surface of the molded product, when observing under a fluorescent light, if the deformation can be visually observed only at a certain fixed angle, it is rated B. Regarding the fiber width of the fabric, if it is more than 75% and less than 80%, it is rated A.

[Example 11] Six prepreg substrates each having a size of 100 mm × 100 mm were cut out from the prepreg with the cutouts used in Example 2. The prepreg substrates were laminated in a manner of [+40/-50] ₃ to prepare a prepreg substrate laminate, and a fiber-reinforced plastic was obtained in the same manner as in Example 5 except that a fabric prepreg as a resin-impregnated sheet was not used.

Various evaluations were performed in the same manner as in Example 1. As a result, [1] the external observation of the protrusion confirmed that the carbon fibers were filled to the tip of each ridge. In addition, [2] the cross-sectional observation of the protrusion confirmed that the carbon fibers connected to the plate-like portion were filled to the inside of each ridge, and the ridge filling property was evaluated as A.

The warping of the plate-shaped part is rated A ⁺ (the warping of the four corners is 0.4mm or more and less than 0.7mm when almost the entire surface of the inspection table is in contact).

Regarding the appearance inspection of the design surface of the molded product, when observing under a fluorescent light, if the deformation can be visually observed only at a certain fixed angle, it is rated B. Regarding the fiber width of the fabric, if it is more than 75% and less than 80%, it is rated A.

[Example 12] A fiber-reinforced plastic is obtained in the same manner as in Example 10, except that one layer of prepreg with an insertion cutout of FAW = 120 g/m ² is layered under the fabric prepreg serving as the design surface, and four layers of prepreg of FAW = 70 g/m ² are further layered thereunder (i.e., the prepreg substrate layer in Example 10 is replaced with a prepreg substrate of FAW = 120 g/m ² and a prepreg of FAW = 70 g/m ² ).

Various evaluations were performed in the same manner as in Example 1. The results showed that [1] the carbon fibers were filled to the tip of each ridge in the external observation of the protrusion. [2] In addition, in the cross-sectional observation of the protrusion, it was confirmed that the carbon fibers connected to the plate-like portion were filled to the inside of each ridge, and the ridge filling property was evaluated as A.

The warping of the plate-shaped part is rated A ⁺ (the warping of the four corners is 0.4mm or more and less than 0.7mm when almost the entire surface of the inspection table is in contact).

Regarding the appearance inspection of the design surface of the molded product, when observing under a fluorescent light, if it can be confirmed that the molded product has no deformation at any angle, it will be rated A. Regarding the fiber width of the fabric, if it is 80% or more and less than 90%, it will be rated A ⁺ .

[Example 13] The prepreg with the cutouts used in Example 7 was laminated in 7 layers in the manner of [45/-50/45/-50/45/-50/45], and the laminated structure was adjusted so that the thickness of the plate-shaped portion became 1.2 mm. The same method as in Example 7 was used to obtain a fiber-reinforced plastic.

Various evaluations were performed in the same manner as in Example 1. The results showed that [1] the carbon fibers were filled to the tip of each ridge in the external observation of the protrusion. [2] In addition, in the cross-sectional observation of the protrusion, it was confirmed that the carbon fibers connected to the plate-like portion were filled to the inside of each ridge, and the ridge filling property was evaluated as A.

The warping of the plate-shaped part is rated A ⁺ (the warping of the four corners is 0.4mm or more and less than 0.7mm when almost the entire surface of the inspection table is in contact).

Regarding the appearance inspection of the design surface of the molded product, when observing under a fluorescent light, if it can be confirmed that the molded product has no deformation at any angle, it will be rated A. Regarding the fiber width of the fabric, if it is 90% or more, it will be rated A ⁺⁺ .

[Example 14] A fiber-reinforced plastic was obtained in the same manner as in Example 8 except that four layers were laminated at a ratio of [40/-20] _s .

Various evaluations were performed in the same manner as in Example 1. The results showed that [1] the carbon fibers were filled to the tip of each ridge in the external observation of the protrusion. [2] In addition, in the cross-sectional observation of the protrusion, it was confirmed that the carbon fibers connected to the plate-like portion were filled to the inside of each ridge, and the ridge filling property was evaluated as A.

The warping of the plate-shaped part is rated A (the warping of the plate-shaped part is not less than 0.7 mm and not more than 1.0 mm at the four corners when the plate is in contact with the entire surface of the inspection table).

Regarding the appearance inspection of the design surface of the molded product, when observing under a fluorescent light, if the deformation can be visually observed only at a certain fixed angle, it is rated B. Regarding the fiber width of the fabric, if it is more than 75% and less than 80%, it is rated A.

[Comparative Example 1] Unidirectional prepregs are laminated in a manner such that the lamination direction becomes [0] ₁₂ (all in the same direction), and the prepreg substrate laminate is accommodated in a mold in a manner such that the fiber orientation direction becomes parallel to the 0° direction of Figure 11. Otherwise, a fiber reinforced plastic is formed in the same manner and under the same conditions as in Example 1 to obtain a fiber reinforced plastic.

Various evaluations were performed in the same manner as in Example 1. The results showed that [1] the carbon fibers were filled to the front end of the protrusion in the external observation of the protrusion. However, [2] the results of the cross-sectional observation of the protrusion showed that the interior of the protrusion extending in the 0° direction of the ridge was filled with only fibers parallel to the extension direction, and no carbon fibers connected to the plate-like portion were observed, resulting in an F evaluation. Therefore, it is believed that although the carbon fibers were filled in the ridge, they could not withstand the shear stress. In addition, in the interior of the protrusion extending outside the 0° direction, it was confirmed that the carbon fibers connected to the plate-like portion were filled in the interior of the ridge.

The warping of the plate-shaped part is rated A (the lifting of the four corners is 0.7 mm or more and less than 1.0 mm when the inspection table is in contact with almost the entire surface).

In addition, regarding the appearance inspection of the design surface of the molded product, observation was carried out under a fluorescent light. As a result, deformation was confirmed at any angle due to the reflected light of the fluorescent light, and the evaluation was F. Next, regarding the skew, it exceeded 1.0 mm and was also evaluated as F.

[Comparative Example 2] Unidirectional prepregs are laminated in a manner such that the lamination direction becomes [90] ₁₂ (all in the same direction), and the prepreg substrate laminate is accommodated in a mold in a manner such that the fiber orientation direction becomes parallel to the 0° direction of Figure 11. Otherwise, a fiber reinforced plastic is formed in the same manner and under the same conditions as in Example 1 to obtain a fiber reinforced plastic.

The evaluation was conducted using the method described in the above-mentioned <Evaluation of the Filling Property of the Protrusion with Fibers and Resins>. The results showed that [1] in the external observation of the protrusion, the carbon fibers were not filled to the front end of the portion extending along the 0° direction of the rib, and "unfilled" and "resin enriched" occurred in the upper part, and the target shape could not be obtained. Regarding the portion extending outside the 0° direction of the rib, the carbon fibers were filled to the front end. Furthermore, [2] the results of the cross-sectional observation of the protrusion showed that the carbon fibers filled in the inner part of the portion extending along the 0° direction of the rib were connected to the carbon fibers in the plate-like portion, but the upper part became only resin, and only the base resin flowed. In addition, it was possible to confirm that in the inner part of the portion extending outside the 0° direction of the rib, the carbon fibers connected to the plate-like portion were filled into the inner part of the rib. Since the target shape could not be obtained, the above-mentioned <Evaluation of warp of molded product> and <Appearance inspection of design surface of molded product> were not carried out.

[Comparative Example 3] A fiber-reinforced plastic was formed in the same manner and under the same conditions as in Example 1, except that the unidirectional prepregs were laminated so that the lamination direction became [0/90] ₆ , thereby obtaining a fiber-reinforced plastic.

The evaluation was conducted using the method described in the above-mentioned <Evaluation of the Filling Property of the Protrusion with Fibers and Resins>. The results showed that, regarding the portion extending along the 0° direction of the rib, [1] according to the external observation of the rib, the carbon fibers were filled to the tip, but [2] according to the results of the cross-sectional observation of the rib, although carbon fibers were observed at the tip of the rib, the carbon fibers were not connected to the carbon fibers existing inside the plate-like portion, and "resin enrichment" occurred. It is believed that only the carbon fibers in the 0° direction of the surface layer flowed, and the carbon fibers below the second layer could not flow to the upper part of the rib. On the other hand, it was confirmed that in the inner part of the portion extending outside the 0° direction of the rib, the carbon fibers connected to the plate-like portion were filled to the inside of the rib. Since the target shape could not be obtained, the above-mentioned <Evaluation of warp of molded product> and <Appearance inspection of design surface of molded product> were not carried out.

[Table 1] Project Embodiment 1 Embodiment 2 Embodiment 3 Embodiment 4 Embodiment 5 Shape of protrusion Y The X-Word The X-Word The X-Word The X-Word Prepreg substrate laminate structure [30/60] ₆ [+40/-50/+40/-50] _s [+40/-50/+40/-50] _s [+40/-50/+40/-50] _s [+40/-50/+40/-50] _s Whether there is incision without have have have have Fabric prepreg on the design side without without have have have Sheet without resin without without Glass Felt CF paper without Resin impregnated sheet without without without without have Fiber filling properties for protrusions (ribs) B A A A A Warp of molded products A ⁺ A ⁺ A ⁺ A ⁺ A ⁺ Design appearance Distortion of reflected light from fluorescent lamps B B A A B Fiber skewness A A ⁺ - - - Fiber Width - - A ⁺⁺ A ⁺⁺ A ⁺⁺

[Table 2] Project Embodiment 6 Embodiment 7 Embodiment 8 Embodiment 9 Shape of protrusion The X-Word The X-Word character H Prepreg substrate laminate structure [+40/-50] ₃ [45/-50/45/-50/45] [0/90] _s [+40/-50] _s Whether there is incision have have have have Fabric prepreg on the design side without without have have Sheet without resin without without without without Resin impregnated sheet without without without without Fiber filling properties for protrusions (ribs) A A A A Warp of molded products A ⁺ A ⁺ A ⁺ A ⁺ Design appearance Distortion of reflected light from fluorescent lamps B B B B Fiber skewness A A - - Fiber Width - - A A

[table 3] Project Embodiment 10 Embodiment 11 Embodiment 12 Embodiment 13 Embodiment 14 Shape of protrusion The X-Word The X-Word The X-Word The X-Word character Prepreg substrate laminate structure [+40/-50] ₃ [+40/-50/] ₃ [+40/-50/+40/-50/+40] [45/-50/45/-50/45/-50/45] [40/-20] _s Whether there is incision have have have have have Fabric prepreg on the design side have have have have have Sheet without resin without without without without without Resin impregnated sheet without without without without without Fiber filling properties for protrusions (ribs) A A A A A Warp of molded products A ⁺ A ⁺ A ⁺ A ⁺ A Design appearance Distortion of reflected light from fluorescent lamps B B A A B Fiber skewness - - - - - Fiber Width A A A ⁺ A ⁺⁺ A

[Table 4] Project Comparison Example 1 Comparison Example 2 Comparison Example 3 Shape of protrusion Y Y Y Prepreg substrate laminate structure [0] ₁₂ [90] ₁₂ [0/90] ₆ Whether there is incision without without without Fabric prepreg on the design side without without without Sheet without resin without without without Resin impregnated sheet without without without Fiber filling properties for protrusions (ribs) F F F Warp of molded products A - ^- Design appearance Distortion of reflected light from fluorescent lamps F - - Fiber skewness F - - Fiber Width - - - [Possibility of industrial application]

The fiber-reinforced plastic of the present invention can be preferably used in components that require strength, rigidity, and lightness, and components that have complex shapes and require shape tracking with other components. In particular, it can be used in components such as cranks and frames of bicycles that have the aforementioned strong requirements, sports components such as shafts and club heads of golf clubs, structural components such as doors, seats, components, modules or frames of automobiles, exterior panels and interior materials, mechanical parts such as robot arms, etc. It can also be preferably used in structural components and exterior panels of other medical equipment and information and communication equipment.

1: Width of the longitudinal section of the protrusion (width of the protrusion) 2: Width of the transverse section of the protrusion (length of the protrusion) 3: Height of the protrusion 4: Prepreg inserted into the cut 5: Fiber orientation direction 6: Fiber vertical direction 7: Intermittent cuts 8: Continuous cuts 9: Intermittent oblique cuts (positive angle relative to the fiber direction) 10: Intermittent oblique cuts (negative angle relative to the fiber direction) 11: Rows of intermittent cuts 20: Length direction of the protrusion 21: Width direction of the protrusion 22: Transverse section of the protrusion 23: Longitudinal section of the protrusion 100: Plate-shaped portion 200: Protrusion 203: Direction of extension of the protrusion 204: The direction in which the protrusion extends 205: The direction in which the protrusion extends 300: Reinforced fiber 400: The surface layer opposite to the surface with the protrusion 401: Reinforced fiber 402: Skew 500: Depression 600: "Unfilled" area

FIG1 is a conceptual diagram showing an example of a protrusion and a plate-like portion in a fiber-reinforced plastic. FIG2 is a conceptual diagram showing an example in which a protrusion extends in two different directions. FIG3 is an explanatory diagram showing the definitions of the fiber length, the length, the angle, and the projection length of the prepreg into which the cut is inserted. FIG4 is an example of a cutting pattern of a prepreg into which the cut is inserted (an example having parallel and continuous cuts). FIG5 is another example of a cutting pattern of a prepreg into which the cut is inserted (an example having parallel and intermittent cuts). FIG6 is another example of a cutting pattern of a prepreg into which the cut is inserted (an example in which the angle with the reinforcing fiber is fixed and the number of positive and negative cuts is approximately half each). FIG. 7 is another example of a cutting pattern of a prepreg with an inserted cut (an example in which the shortest distance between adjacent cuts is longer than the length of the cut). FIG. 8 is a conceptual diagram showing the presence/height of a skew in the surface of a fiber-reinforced plastic (the surface opposite to the surface having a protrusion). FIG. 9 is a conceptual diagram showing the orientation direction of the reinforcing fibers in the protrusion and the plate-shaped portion constituting the fiber-reinforced plastic. FIG. 10 is a conceptual diagram showing an example of the shape of the protrusion protruding from the plate-shaped portion. FIG. 11 is a diagram showing a molded body having a Y-shaped rib manufactured by a mold having a Y-shaped rib groove. FIG. 12 is a diagram showing a molded body having an X-shaped rib manufactured by a mold having an X-shaped rib groove. FIG. 13 is a conceptual diagram of a fiber-reinforced plastic having an H-shaped protrusion formed in an embodiment. FIG. 14 is a conceptual diagram of a fiber-reinforced plastic having a V-shaped protrusion formed in an embodiment. FIG. 15 is a conceptual diagram of a fiber-reinforced plastic having an S-shaped protrusion formed in an embodiment.

100: Plate-shaped part

a: protrusion

b: protrusion

Claims (12)

A fiber-reinforced plastic, which is a fiber-reinforced plastic having a plate-like portion and at least one protrusion protruding from at least one side of the plate-like portion, wherein the plate-like portion has at least one layer (unidirectional layer) in which a plurality of reinforcing fibers are arranged in one direction in a base resin, the protrusion extends in at least two different directions, and at least two of the directions in which the protrusion extends are non-parallel and non-perpendicular to each other, and all the directions in which the protrusion extends are non-parallel and non-perpendicular to the fiber orientation direction in any one of the unidirectional layers in the plate-like portion. The fiber reinforced plastic of claim 1 has at least one unidirectional layer in which the fiber orientation direction is neither parallel nor perpendicular to the direction in which the protrusions extend. The fiber-reinforced plastic of claim 1 or 2, wherein the plate-like portion has at least two unidirectional layers, and the fiber orientation directions of the two unidirectional layers are not parallel to each other. The fiber-reinforced plastic of claim 1 or 2, wherein the plate-like portion has at least two unidirectional layers, and the fiber orientation directions of the two unidirectional layers are perpendicular to each other. A fiber-reinforced plastic as claimed in claim 1 or 2, wherein the angle formed by all directions in which the aforementioned protrusions extend and the fiber orientation direction in any unidirectional layer in the aforementioned plate-like portion is 15° to 80° or 100° to 165°. The fiber reinforced plastic of claim 1 or 2, wherein among the aforementioned unidirectional layers located inside the aforementioned plate-like portion, at least one layer has a fiber basis weight of not less than 70 g/ ^m2 and not more than 200 g/ ^m2 . A fiber-reinforced plastic as claimed in claim 1 or 2, wherein at least one layer of the aforementioned unidirectional layers located inside the aforementioned plate-like portion contains reinforcing fibers having a fiber length of 10 to 300 mm. The fiber-reinforced plastic of claim 1 or 2, wherein the interior of the plate-like portion comprises two or more unidirectional layers having different fiber basis weights. A fiber-reinforced plastic as claimed in claim 8, wherein the outermost layer on the side of the aforementioned protrusion in the aforementioned plate-like portion is a unidirectional layer, and the fiber basis weight of the unidirectional layer being the outermost layer is smaller than the fiber basis weight of at least one other unidirectional layer in the aforementioned plate-like portion. A fiber-reinforced plastic as claimed in claim 1 or 2, wherein the plate-like portion has a plurality of layers consisting of reinforcing fibers and a matrix resin, only one side of the plate-like portion has the protrusion, and at least one of the layers other than the outermost layer of the surface having the protrusion is a layer (non-unidirectional layer) in which a plurality of reinforcing fibers are oriented in at least two directions in the matrix resin. A fiber-reinforced plastic as claimed in claim 1 or 2, wherein the plate-like portion has a plurality of layers consisting of reinforcing fibers and a matrix resin, only one side of the plate-like portion has the protrusion, and the outermost layer of the surface on the opposite side is made of the reinforcing fibers as a fabric. A method for manufacturing a fiber-reinforced plastic comprises placing at least one layer of a prepreg formed by impregnating a matrix resin into a plurality of reinforcing fibers arranged in one direction in a mold, closing the mold and applying heat and pressure to obtain the fiber-reinforced plastic as claimed in claim 1 or 2.

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