Fiber reinforced plastic and golf club

Abstract

The present application relates to fiber-reinforced plastic and golf clubs, and aims to provide a fiber-reinforced plastic having a protrusion portion, which is lightweight and excellent in mechanical properties and appearance quality, the fiber-reinforced plastic being formed in a shape having a plate-shaped portion and at least one protrusion portion protruding from at least one side surface of the plate-shaped portion, wherein at least one layer (unidirectional layer) in which a plurality of reinforcing fibers are arranged in a unidirectional manner in a matrix resin is provided inside the plate-shaped portion, the thickness t of the plate-shaped portion is 0.3 mm or more and 1.8 mm or less, and the ratio w / t of the maximum width w of the protrusion portion to the thickness t of the plate-shaped portion is 0.1 or more and 27 or less.

Description

Technical Field

[0001] The present invention relates to fiber-reinforced plastics having a plate-like portion and a protrusion extending from at least one side of the plate-like portion, and more specifically, to fiber-reinforced plastics having the aforementioned plate-like portion and protrusions formed of a plurality of reinforcing fibers and a matrix resin. Background Technology

[0002] Fiber-reinforced plastics, formed from reinforcing fibers and matrix resins, are attracting attention due to their high specific strength, specific elastic modulus, excellent mechanical properties, and high functional characteristics such as weather resistance and chemical resistance. They are expected to be effectively utilized in a wide range of fields, including industry, sports, medicine, and information and communication.

[0003] Furthermore, in order to improve the mechanical properties of fiber-reinforced plastics and promote thinner walls and lighter weight while maintaining these properties, efforts have been made to refine the cross-sectional shape of the molded parts, resulting in the design of fiber-reinforced plastics with varying wall thicknesses and rib shapes. In particular, rib shapes are effective in preventing warping of wide planar portions of the molded parts, but because the shape becomes more complex, there are challenges in terms of moldability and mass production.

[0004] Methods for manufacturing fiber-reinforced plastics with high functional properties include autoclave molding and pressure molding. In autoclave molding, a semi-cured material, called a prepreg, obtained by impregnating a thermosetting resin (as the matrix resin) into a continuous sheet or fabric of reinforcing fibers, is layered. The matrix resin is then cured by heating and pressurizing in a high-temperature autoclave (autoclave) to form the fiber-reinforced plastic. In pressure molding, the aforementioned prepregs are layered, the resulting material is placed into a mold, and heated and pressurized using a press to cure the thermosetting resin matrix resin; alternatively, a prepreg impregnated with a thermoplastic resin as the matrix resin is softened or melted, molded, and then cooled and demolded to form the final product. Especially in pressure molding using thermosetting resins, prepregs made by using fast-curing thermosetting resins as the matrix resin and impregnating them with reinforcing fibers can produce molded products in a short time. Therefore, as a high-productivity molding method, it has attracted attention in recent years.

[0005] In the molding method using the prepreg preform described above, when producing molded articles with complex shapes such as varying wall thickness or ribbed shapes, the following method is possible: the desired fiber-reinforced plastic is subdivided into plate-shaped parts, rib-shaped parts, etc., and each part is molded separately, then joined together using an adhesive or thermal fusion bonding. However, since the bonding process is time-consuming and costly, and the strength and rigidity of the joint are lower than other parts, failure will occur at the joint first, making it difficult to fully utilize the excellent mechanical properties and durability of the fiber-reinforced plastic.

[0006] On the other hand, there is a method that involves shaping the preform on a mold before molding, followed by molding. While this method solves the problem of damage caused by the joint, the shaping process is time-consuming, thus raising concerns about production efficiency and cost.

[0007] Furthermore, when using fiber-reinforced plastics (FRPs) to manufacture various components, in addition to the aforementioned moldability and mass production capabilities, appearance quality is sometimes required. The unique linear style, Japanese paper style, and fabric patterns inherent in FRPs become factors that enhance the added value of the product. However, in shapes with varying wall thickness or ribs, the flow of reinforcing fibers becomes intense during molding, disrupting the aforementioned unique appearance and making it difficult to achieve the desired quality. Increasing the thickness of the molded part can reduce the impact of reinforcing fiber flow caused by variations in wall thickness and ribs, or applying a high-quality appearance layer to the design surface, but improvements are desired from the perspective of lightweighting and production efficiency.

[0008] Attempts to improve upon the aforementioned problems of the prior art have been proposed (Patent Documents 1 and 2).

[0009] Patent Document 1 discloses a method for manufacturing fiber-reinforced plastics, in which at least two prepreg blanks with inserted slits and fiber lengths adjusted to 10-100 mm are stacked and press-molded to form a rib shape. While this method addresses the rigidity and material balance of the molded product, it does not study the impact on appearance quality. Furthermore, it focuses on molding thick components, presenting challenges in achieving lightweight design.

[0010] Patent document 2 illustrates that in fiber-reinforced plastics formed from laminates of fabric prepregs and discontinuous fiber prepregs, fiber-reinforced plastics with less fabric mesh disorder can be obtained when the heat of resin generation in each prepreg meets specified conditions. While this document also describes the appearance quality during rib forming, it does not describe the rib width or the thickness of the plate-like portion, and its reinforcing effect and lightweight properties are unclear.

[0011] Existing technical documents Patent documents Patent Document 1: International Publication No. 2008 / 038429 Patent Document 2: International Publication No. 2019 / 031111 Summary of the Invention

[0012] The problem that the invention aims to solve The purpose of this invention is to improve upon the problems of the prior art and provide a lightweight fiber-reinforced plastic with protrusions that has excellent mechanical properties and appearance.

[0013] Methods for solving problems The present invention, which achieves the above objectives, is described in any of the following descriptions.

[0014] (1) A fiber-reinforced plastic formed of a shape having a plate-like portion and at least one protrusion raised from at least one side of the plate-like portion, wherein the plate-like portion has at least one layer (unidirectional layer) in which multiple reinforcing fibers are arranged unidirectionally in a matrix resin, the thickness t of the plate-like portion is 0.3 mm or more and 1.8 mm or less, and the ratio w / t of the maximum width w of the protrusion to the thickness t of the plate-like portion is 0.1 or more and 27 or less.

[0015] (2) The fiber-reinforced plastic as described in (1) above, wherein the fiber volume content (Vf) of the aforementioned fiber-reinforced plastic is 43% to 58%.

[0016] (3) The fiber-reinforced plastic as described in (1) or (2) above, wherein the ratio w / t of the maximum width w of the protrusion to the thickness t of the plate-like portion is 2 or more and 27 or less.

[0017] (4) The fiber-reinforced plastic as described in any one of (1) to (3) above, wherein there are two or more of the aforementioned unidirectional layers inside the aforementioned plate-shaped portion, and the fiber orientation direction of the two aforementioned unidirectional layers from the side with the aforementioned protrusion is not parallel to and not perpendicular to the length direction of the protrusion.

[0018] (5) The fiber-reinforced plastic as described in any one of (1) to (4) above, wherein the fiber unit area weight of at least one of the aforementioned unidirectional layers located inside the aforementioned plate-shaped portion is 70 g / m². 2 Above 100g / m 2 the following.

[0019] (6) The fiber-reinforced plastic as described in any one of (1) to (5) above, wherein the plate-shaped portion has multiple layers formed of reinforcing fibers and matrix resin, the aforementioned protrusion is only on one side of the plate-shaped portion, and the aforementioned reinforcing fibers forming the outermost layer of the opposite side of the one-sided surface are fabric.

[0020] (7) The fiber-reinforced plastic as described in (6) above, wherein the thickness of the mesh of the aforementioned fabric is less than 0.25 mm.

[0021] (8) The fiber-reinforced plastic as described in any one of (1) to (7) above, wherein the radius of curvature R of the surface formed by the aforementioned protrusion and the aforementioned plate-shaped portion is 2 mm or less.

[0022] (9) The fiber-reinforced plastic as described in any one of (1) to (8) above, wherein the maximum width w of the aforementioned protrusion is 8 mm or less.

[0023] (10) The fiber-reinforced plastic as described in any one of (1) to (9) above, wherein the interior of the aforementioned plate-shaped portion has two or more of the aforementioned unidirectional layers with different fiber unit area weights.

[0024] (11) The fiber-reinforced plastic as described in (10) above, wherein the outermost layer on the side of the plate-shaped portion with the protrusion is the unidirectional layer, and the fiber unit area weight of the outermost unidirectional layer is less than the fiber unit area weight of at least one other unidirectional layer in the plate-shaped portion.

[0025] (12) The fiber-reinforced plastic as described in any one of (1) to (11) above, wherein the aforementioned plate-shaped portion has multiple layers formed of reinforcing fibers and matrix resin, the aforementioned protrusion is only on one side of the aforementioned plate-shaped portion, and at least one of the layers other than the outermost layer of the surface with the protrusion is a layer (non-unidirectional layer) in which multiple reinforcing fibers are oriented in at least two directions in the matrix resin.

[0026] (13) The fiber-reinforced plastic as described in any one of (1) to (12) above, wherein the plate-shaped portion has a non-unidirectional layer and the ratio w / t' of the maximum width w of the protrusion to the total thickness t' of the unidirectional layer located on the protrusion side relative to the non-unidirectional layer is 0.1 or more and 27 or less.

[0027] (14) The fiber-reinforced plastic as described in any one of (1) to (13) above, wherein at least one of the aforementioned unidirectional layers located inside the aforementioned plate-shaped portion comprises reinforcing fibers with a fiber length of 10 to 300 mm.

[0028] (15) A method for manufacturing fiber-reinforced plastic, wherein at least one layer of prepreg blank, in which a matrix resin is impregnated to a plurality of reinforcing fibers arranged in a unidirectional manner, is disposed in a mold, the mold is closed and heated and pressurized to obtain the fiber-reinforced plastic as described in any one of (1) to (14) above.

[0029] (16) A golf club having the fiber-reinforced plastic described in any one of (1) to (14) above.

[0030] Invention Effects According to the present invention, it is possible to provide a lightweight fiber-reinforced plastic with protrusions that has excellent mechanical properties and appearance quality. Attached Figure Description

[0031] Figure 1 This is a conceptual diagram illustrating an example of the protrusions and plate-like portions constituting the fiber-reinforced plastic involved in the present invention.

[0032] Figure 2 An explanatory diagram illustrating the definitions of fiber length inserted into the prepreg blank, and the respective definitions of the length, angle, and projected length of the cut.

[0033] Figure 3 An example of a cutting pattern for inserting a notch into a prepreg blank (an example with parallel and continuous notches).

[0034] Figure 4 Other examples of cutting patterns for inserting slits into prepreg blanks (examples with parallel and discontinuous slits).

[0035] Figure 5 Other examples of cutting patterns for inserting slits into prepreg blanks (examples where the angle with the reinforcing fiber is constant and the positive and negative slits are approximately equal).

[0036] Figure 6 Other examples of cutting patterns for inserting slits into prepreg blanks (examples where the shortest distance between adjacent slits is longer than the length of the slit).

[0037] Figure 7 This is an example of a longitudinal section view of a fiber-reinforced plastic with protrusions.

[0038] Figure 8 A schematic diagram illustrating the mesh distortion in the surface of fiber-reinforced plastic (the side opposite to the side with the protrusions).

[0039] Figure 9 Other examples of longitudinal cross-sectional views of fiber-reinforced plastics with protrusions (examples where the outermost layer of the side opposite to the side with the protrusions is a non-unidirectional layer).

[0040] Figure 10 A schematic diagram illustrating an example of the shape of a protrusion rising from a plate-like portion.

[0041] Figure 11 A conceptual diagram illustrating the orientation of reinforcing fibers in the protrusions and plate-like portions that constitute fiber-reinforced plastics.

[0042] Figure 12 Other examples of longitudinal cross-sectional views of fiber-reinforced plastics with protrusions. Detailed Implementation

[0043] The fiber-reinforced plastic of the present invention has at least one layer (hereinafter sometimes referred to as a unidirectional layer) in which multiple reinforcing fibers are arranged in a matrix resin in a unidirectional manner, for example, as shown in the figure. Figure 1 As shown, the fiber-reinforced plastic is formed from a shape having a plate-like portion 100 and at least one protrusion 200 raised from at least one side of the plate-like portion 100. As described above, at least one unidirectional layer is present inside the aforementioned plate-like portion 100.

[0044] Here, the shape of the protrusion when viewed from above the surface of the plate-like portion is defined as the planar shape of the protrusion, the direction in which this planar shape extends is defined as the direction of extension of the protrusion (hereinafter, sometimes also referred to as the length direction), and the direction perpendicular to the length direction in this planar shape is defined as the width direction of the protrusion. Here, the direction of extension of the planar shape refers to the major axis direction when the planar shape is elliptical, the long side direction when the planar shape is rectangular, and the long side direction of the rectangle with the smallest area circumscribed to that shape when the planar shape is otherwise. Furthermore, a cross-section that is parallel to the length direction of the protrusion and perpendicular to the planar direction of the plate-like portion, where the length direction of the protrusion is maximized, is called the cross-section of the protrusion, and a cross-section that is parallel to the width direction of the protrusion and perpendicular to the planar direction of the plate-like portion, where the width direction of the protrusion is maximized, is called the longitudinal section of the protrusion. As an example, when the planar shape of the protrusion is... Figure 1 In the case of such an ellipse, the major axis direction of the ellipse becomes the length direction 20 of the protrusion, the minor axis direction becomes the width direction 21 of the protrusion, the cross section perpendicular to the plane direction of the plate-like part along the major axis becomes the cross section 22 of the protrusion, and the cross section perpendicular to the plane direction of the plate-like part along the minor axis becomes the longitudinal section 23 of the protrusion.

[0045] Furthermore, when the protrusion extends along different bidirectional directions, for example, for shapes whose planar shape can be defined by combinations of rectangles or ellipses (such as X-shapes, V-shapes, H-shapes, or Y-shapes), it is interpreted that the protrusion has multiple length directions. That is, it is interpreted that the planar shape of the protrusion is X-shaped or V-shaped and has two length directions, and that it is H-shaped or Y-shaped and has three length directions. Based on this, the aforementioned planar shape is decomposed into multiple shapes, which are interpreted as having multiple cross-sections and longitudinal sections corresponding to each direction.

[0046] Figure 7 The diagram shows a longitudinal cross-sectional view of the protrusion 200 rising from the plate-like portion. The width of the protrusion 200 can be as follows: Figure 7 The front and root portions can be different, or they can be the same. However, a wider root portion compared to the front makes it easier to remove from the mold during demolding and also helps to reduce stress concentration when subjected to loads during use, therefore it is preferred. Furthermore, as... Figure 7 When the shape of the front end and the root of the protrusion are different, the shape of the root is set to the planar shape of the protrusion.

[0047] Preferably, the protrusion 200 and the plate-like portion 100 are connected by a curved surface, and the radius of curvature R is preferably 2 mm or less, more preferably 1 mm or less. If the radius of curvature R is 2 mm or less, the volume at the root of the protrusion will not become too large, so the unidirectional prepreg blank, as described later, is fully filled into the protrusion. Therefore, "resin enrichment" with a high resin ratio is less likely to occur, and the appearance quality degradation caused by the occurrence of depressions on the design side (the side opposite to the side where the protrusion exists when the protrusion exists on only one side) and the mesh twisting of the reinforcing fibers can be suppressed. If the radius of curvature R is too small, the boundary portion (hereinafter referred to as the joint or junction) between the protrusion 200 and the plate-like portion 100 becomes sharp, and sometimes the reinforcing fibers are touched and cut, making mold processing difficult. Therefore, it is preferable to set it to about 0.2 mm.

[0048] In this invention, the maximum width in the longitudinal section of the protrusion is defined as the maximum width w of the protrusion. That is, in Figure 7In this shape, the distance 202 between the two ends of the joint between the plate-like portion 100 and the protrusion 200 is set as the maximum width w of the protrusion. Furthermore, when the plate-like portion and the protrusion are connected by a curved surface, the maximum width refers to the distance including the curved surface. The maximum width of the protrusion is preferably 8 mm or less, more preferably 5 mm or less. When the maximum width of the protrusion is 8 mm or less throughout the entire area of ​​the protrusion, even if the thickness of the plate-like portion is as thin as 1.8 mm or less, a fiber-reinforced plastic with high appearance quality can be obtained, thus achieving thin-walled and lightweight construction. Furthermore, when the protrusion has multiple longitudinal sections extending in different bidirectional directions as described above, the maximum width of the longitudinal section where the maximum width is greatest is set as the maximum width of the protrusion.

[0049] The shape of the plate-shaped portion 100 is not particularly limited, and the thickness 101 of the plate-shaped portion is in the range of 0.3 to 1.8 mm. The thickness can be arbitrarily designed by adjusting the amount of fiber and matrix resin used. As a method to adjust the amount of fiber and matrix resin used, in addition to adjusting the number of layers of fiber substrate constituting the plate-shaped portion, other methods include changing the amount of matrix resin and changing the type of fiber.

[0050] When the fiber-reinforced plastic of the present invention is used in structural components, outer panels such as covers, and other parts in vehicles such as automobiles and motorcycles, bicycles, sports equipment such as golf clubs, and medical devices, the thickness t of the plate-like portion is 0.3 to 1.8 mm, considering both the required mechanical properties and lightweight design, and practicality. Furthermore, when rigidity and lightweight are particularly required for the plate-like portion, a thickness of 0.5 to 1.2 mm is preferred. In particular, when the fiber-reinforced plastic is used in components requiring strict lightweight design, such as golf club heads, the weight distribution design has a significant impact on flight distance and feel, thus sometimes requiring a design in units of 0.1 g. For example, a design with a fiber unit area weight of 100 g / m² is preferred. 2 In the case of a molded article formed from a 100mm × 100mm prepreg blank with a resin mass fraction (Rc) of 40%, a difference of 0.1mm in the thickness of the plate-shaped portion will result in a weight change of approximately 1-2g. Therefore, adjusting the thickness of the plate-shaped portion, which has a significant impact on weight, becomes very important. When the thickness of the plate-shaped portion exceeds 1.8mm, its application in components requiring lightweight construction becomes difficult. It should be noted that, in this invention, the thickness of the plate-shaped portion refers to the thickness 101 of the plate-shaped portion at the junction of the plate-shaped portion 100 and the protrusion 200 in the longitudinal section (or the junction of the curved surface and the plate-shaped portion if the plate-shaped portion and the protrusion are connected by a curved surface).

[0051] In this invention, the ratio w[mm] of the maximum width of the protrusion to t[mm] of the plate-like portion, w / t, is 0.1 or more and 27 or less. As an upper limit, it is preferably 10 or less, and more preferably 5 or less. When w / t exceeds 27, insufficient reinforcing fibers fill the protrusion, resulting in depressions on the design surface, or resin enrichment occurs at the root of the protrusion, making the reinforcing fibers on the design surface side more prone to flow, resulting in a decrease in appearance quality due to the twisting of the reinforcing fibers (mesh twisting). Figure 8 The diagram shows the design surface. (A) shows the state where the reinforcing fibers 401 are aligned in one direction without mesh twisting, and (B) shows the state with mesh twisting 402. The greater the degree of mesh twisting, the worse the appearance quality. Although a smaller w / t is better from the viewpoint of appearance quality, the effect of appearance quality saturates below a certain level, and conversely, the reinforcing effect of the protrusions becomes smaller. Therefore, from the viewpoint of appearance quality and the filling effect of the reinforcing fibers on the protrusions, as well as the strength of the protrusions, it is preferable to have a w / t of 0.1 or more, more preferably 2 or more, and even more preferably 3 or more. If w / t is 2 or more, it is possible to further expect to achieve both good appearance quality and improved strength of the molded article. In addition, for example, Figure 7 When the thickness 101 of the plate-shaped portion is different on the left and right sides of the protrusion, the smaller thickness of the plate-shaped portion is set as the thickness t of the plate-shaped portion.

[0052] To obtain fiber-reinforced plastics with high appearance quality, it is preferable that not only the longitudinal section as defined above, but also the length corresponding to the width of the protrusion to the length corresponding to the thickness of the plate-like portion in all sections parallel to the longitudinal section, including the protrusion, is 27 or less. However, for example, in cases where appearance quality is not required in a certain area and a wider protrusion is desired, a portion of the above ratio exceeding 27 may be intentionally provided in a section of the cross-section other than the longitudinal section.

[0053] It should be noted that the maximum width of the protrusion and the thickness of the plate-like part can be measured by using vernier calipers or micrometers to measure the distance between the two ends of the joint between the protrusion and the plate-like part, or by observing the cross-section with a microscope and calculating it through image analysis.

[0054] The height 203 of the protrusion in the fiber-reinforced plastic of the present invention is not particularly limited and can be designed arbitrarily, but is preferably 0.1 to 50 mm, more preferably 0.1 to 20 mm, and even more preferably 1 to 10 mm. It should be noted that when the thickness 101 of the plate-like portion differs between the left and right sides of the protrusion, the height of the protrusion is based on the thickness of the smaller plate-like portion. If the height of the protrusion exceeds 50 mm, there is a possibility that unfilled portions of the unidirectional prepreg blank will not be filled to the front end of the protrusion, as described later. If it is less than 0.1 mm, the reinforcing effect may be reduced, and the significance of providing the protrusion may be weakened.

[0055] Furthermore, when the height of the protrusion is 1 to 6 mm, the amount of the groove in the mold that forms the protrusion in the fiber substrate constituting the plate-shaped part will not become excessive, which can more reliably prevent the generation of fiber orientation disorder and surface depression in the design surface of fiber-reinforced plastic, and is therefore the most preferred.

[0056] In the fiber-reinforced plastic of the present invention, preferably at least one layer of the layers other than the outermost layer of the surface of the plate-like portion 100 having protrusions is a non-unidirectional layer 102. Further, as... Figure 9 As shown, the outermost layer of the preferred plate-shaped portion 100, which is opposite to the surface with the protrusion, is a non-unidirectional layer 102.

[0057] Here, a non-unidirectional layer refers to a layer in which the reinforcing fibers are not arranged in only one direction, that is, a layer in which the fiber direction is oriented in at least two directions. More specific examples of a non-unidirectional layer include a fabric where the fibers are arranged in at least two defined directions, or a nonwoven fabric where the fibers are randomly oriented, etc., without particular limitation. It should be noted that in this invention, the non-unidirectional layer refers to one of the layers constituting the plate-like portion of the fiber-reinforced plastic, and the material equivalent to the non-unidirectional layer before molding the fiber-reinforced plastic is called a non-unidirectional reinforcing fiber sheet. Regarding the non-unidirectional reinforcing fiber sheet, as mentioned above, any form is acceptable as long as the reinforcing fibers are not arranged in only one direction but in multiple directions; it can be a state without matrix resin (dry sheet) or a reinforcing fiber sheet in which matrix resin is pre-impregnated in at least a portion of the area.

[0058] like Figure 9 As shown, when the plate-shaped portion has a non-unidirectional layer 102, and the total thickness 103 of the unidirectional layers located on the protrusion side of the plate-shaped portion thickness 101 relative to the non-unidirectional layers is set as t', it is preferable that the ratio w / t' of the maximum width w [mm] of the protrusion to the total thickness t' [mm] of the unidirectional layers is 0.1 or more and 27 or less. As an upper limit, it is more preferably 10 or less, and most preferably 5 or less. When w / t' exceeds 27, sometimes the reinforcing fiber sheet filling the protrusion is insufficient, resulting in a depression on the design surface, or resin accumulation at the root of the protrusion, etc., causing the reinforcing fibers on the design surface to flow easily and causing a shift in fiber direction, resulting in a decrease in appearance quality. From the viewpoint of appearance quality, the smaller w / t' is, the better, but from the viewpoint of the filling ability of the reinforcing fibers to the protrusion and the strength of the protrusion, it is preferable to be 0.1 or more, more preferably 2 or more, and even more preferably 3 or more. In addition, for example Figure 9 In cases where the total thickness of the unidirectional layer 103 differs between the left and right sides of the protrusion, the smaller total thickness is set as the total thickness t'.

[0059] The shape of the protrusion rising from the plate-like portion is not particularly limited, and various forms can be adopted depending on the purpose. For example, the shape viewed from the upper surface of the plate-like portion can be, in addition to being... Figure 1 Besides the elliptical protrusion shown, other protrusions that can be polygonal (e.g., rectangular), circular, X-shaped, V-shaped, H-shaped, I-shaped, Y-shaped, L-shaped, etc., can also be included. Furthermore, they can be combined. It should be noted that... Figure 10 (A) shows a protrusion with an X-shape. Figure 10 (B) shows a protrusion with an I-shape. Figure 10 (C) shows the way in which the H-shaped protrusion is shown. Figure 10 (D) shows a way of having multiple I-shaped protrusions.

[0060] In addition, the cross-sectional shape and longitudinal section shape of the protrusion can be, for example, polygonal (e.g., rectangle, triangle) or semi-circular.

[0061] Regarding the cross-sectional shape and height of the protrusion, although it is possible to set all of the multiple protrusions to have the same shape and size, it is also possible to vary them according to the concave and convex shape and curvature shape of the fiber reinforced plastic, and it is also possible to partially manufacture parts that are not the aforementioned shapes.

[0062] In the fiber-reinforced plastic of the present invention, protrusions can be disposed at any position on the plate-like portion. Furthermore, the placement position of the protrusions can be confirmed during top-view observation of the entire fiber-reinforced plastic, allowing for a clear assessment of the appearance of the protrusions. The placement position of the protrusions is not limited to one location; they can be disposed at two or more locations. That is, protrusions of the same or different shapes can be provided at two or more locations.

[0063] It should be noted that, in terms of the number of protrusions, when viewed from above, the parts that are visible as plate-like portions are considered not to be protrusions. The smallest protrusion surrounded by the plate-like portion is identified as an independent protrusion and counted.

[0064] When ribs are provided as protrusions, in order to simultaneously achieve both lightweighting and increased rigidity of the fiber-reinforced plastic as described in this invention, it is preferable to provide ribs at two or more locations, not just one. This expands the reinforcement range of the plate-like portion. Furthermore, by arranging ribs at two or more locations and ensuring their length directions are parallel to each other, a reinforcement effect can be achieved. In this case, the ribs can also be provided discontinuously and intermittently. On the other hand, even when the length directions of multiple ribs are not parallel to each other (e.g., in a "H" shape), these length directions can be arranged in any direction according to the required mechanical properties of the fiber-reinforced plastic.

[0065] In terms of the shape of the ribs, it is not only a straight shape with only one direction in the length direction, but also a cross shape (X shape) with ribs in at least two directions intersecting at any position at an angle, a V shape (including a shape obtained by connecting multiple crosses), and further, a shape in which at least three ribs intersect radially at any angle at one point. It can be designed arbitrarily according to the mechanical properties required by the fiber reinforced plastic.

[0066] Furthermore, the fiber-reinforced plastic of the present invention is characterized in that, inside the plate-like portion, there is at least one layer (unidirectional layer) in which multiple reinforcing fibers are arranged unidirectionally in the matrix resin. Here, "inside the plate-like portion" refers to the portion corresponding to the plate-like portion, which can be the portion constituting the surface layer or the inner layer portion outside of it. It should be noted that, in the present invention, the material equivalent to the unidirectional layer before the fiber-reinforced plastic is molded is referred to as a unidirectional prepreg preform.

[0067] In the fiber-reinforced plastic of the present invention, for example when manufacturing a preform that serves as its precursor, it is preferable to arrange at least one layer of unidirectional prepreg preform in a manner where the fiber orientation direction is neither parallel nor perpendicular to the length direction of the protrusion. Here, "neither parallel nor perpendicular" means a state that is neither parallel nor perpendicular, implying that it is only inclined relative to the width direction in the cross-section of the protrusion. That is, although, for example... Figure 11 (A) to (C) show how the reinforcing fibers constituting the unidirectional prepreg extend in the longitudinal direction (rib direction, paper depth direction) or orthogonal to the protrusions, but not in such a manner, but rather as follows: Figure 11 As shown in (D), this refers to the reinforcing fibers not extending along the longest direction of the protrusion or in a direction or perpendicular to it. It should be noted that... Figure 11 (A) shows the arrangement in which the reinforcing fiber 300 is parallel to the longitudinal direction (rib direction) of the protrusion 200. Figure 11 (B) shows the reinforcing fiber 300 perpendicular to the length direction (rib direction) of the protrusion 200, further, Figure 11 (C) shows that the reinforcing fiber 300 is parallel and perpendicular to the longitudinal direction (rib direction) of the protrusion 200. On the other hand, Figure 11 (D) shows the state in which the cross section of the reinforcing fiber 300 becomes flat because the length direction (rib direction) of the reinforcing fiber 300 is neither parallel nor perpendicular to the length direction (rib direction) of the protrusion 200 (i.e., it is neither parallel nor perpendicular).

[0068] The so-called "at least one layer of unidirectional prepreg preforms arranged in a manner where the orientation of the reinforcing fibers is neither parallel nor perpendicular to the length direction of the protrusions" in the final fiber-reinforced plastic means that the reinforcing fibers extending along the longest direction of the protrusions are reduced. Therefore, it is possible to suppress... Figure 11 As shown in (A), the indentation 500 in the protrusion of the fiber-reinforced plastic along the direction of fiber stranding inhibits, as Figure 11 As shown in (B) and (C), the generation of "unfilled" fibers and resins is reduced, the generation of so-called "resin enrichment" is suppressed, and the appearance quality is improved at the same time.

[0069] When the fiber orientation is parallel to the length of the protrusion, the protrusion becomes less able to withstand shear loads. Therefore, the protrusion lacks strength and is prone to cracking along the fiber orientation, leading to breakage and peeling from the plate-like portion. Furthermore, when the fiber orientation is perpendicular to the length of the protrusion, the reinforcing fibers become difficult to flow into the interior of the protrusion (the concave part of the mold) during molding, sometimes resulting in unfilled areas of reinforcing fibers within the molded protrusion. Additionally, if the reinforcing fibers become difficult to flow, the matrix resin may be extruded from the unidirectional prepreg, locally creating areas containing only resin (resin enrichment).

[0070] Furthermore, as described above, when the protrusions extend in different bidirectional directions, it is preferable that the fiber orientation direction of at least one layer of the layer formed by arranging unidirectional prepreg blanks is neither parallel nor perpendicular to the length direction of at least one protrusion.

[0071] It should be noted that the angle between the fiber orientation direction and the length direction of the protrusion (the angle formed by the orientation direction of the reinforcing fiber and the length direction of the protrusion) is not particularly limited as long as it is neither parallel nor perpendicular to the fiber orientation direction, and is preferably 5 to 85°. Furthermore, from the viewpoint of filling the protrusion and the bonding strength between the protrusion and the plate-like portion, it is even more preferably 30 to 60°.

[0072] When two or more unidirectional prepreg blanks are stacked to form a plate-like portion, it is preferable to stack as many layers as possible in which the fiber orientation direction of each layer is neither parallel nor perpendicular to the length direction of the protrusion. In this case, there is no particular limitation on the angular difference in the fiber orientation directions between layers; all layers can be filaments in the same direction or different directions. This can be freely chosen according to the desired properties of the composite material. However, having layers with non-parallel fiber orientation directions has advantages such as the protrusion being able to withstand loads from multiple directions and reduced warpage of the molded article (fiber-reinforced plastic), and is therefore preferred.

[0073] When multiple unidirectional prepreg blanks with different orientations of reinforcing fibers are laminated, [0 / 90]n is typically used. S Such symmetrical layering, [0 / ±60]n S [+45 / 0 / -45 / 90]n S Such isotropic lamination, and symmetrical lamination structure with respect to the lamination direction (thickness direction), is effective for reducing warpage in the plate-like portion of fiber-reinforced plastics. On the other hand, in the fiber-reinforced plastic of the present invention, since warpage can be reduced by making the protrusions rib-shaped, the orientation direction of the fibers can be biased towards the rigidity direction required by the fiber-reinforced plastic.

[0074] Furthermore, while the stacking order of the unidirectional prepreg blanks can be arbitrarily set, from a formability perspective, it is preferable to stack layers in a manner where the fiber orientation direction is neither parallel nor perpendicular to the length direction of the protrusions, located near the protrusions. Preferably, in the plate-shaped portion, it is ideal to place the unidirectional prepreg blank within the fourth layer from the surface with the protrusions; most preferably, the unidirectional prepreg blank is placed on the outermost layer of the surface with the protrusions. Furthermore, it is also preferable that the first two layers from the outermost layer of the surface with the protrusions, and more preferably all layers from that outermost layer up to the fourth layer, are all layers in which the fiber orientation direction is neither parallel nor perpendicular to the length direction of the protrusions.

[0075] Furthermore, the number of layers in the unidirectional prepreg can be increased according to the properties required for the fiber-reinforced plastic. The more layers the unidirectional prepreg has, the more fibers flow towards the protrusions, which is therefore preferable. Preferably, there are 4 or more layers, more preferably 6 or more layers. By laminating in this way, the reinforcing fibers can easily flow towards the protrusions, and the reinforcing fibers can easily fill the ends of the protrusions, which is preferable from the viewpoint of moldability and the mechanical properties of the protrusions.

[0076] Furthermore, when there are two or more protrusions, the prepreg blank may have varying filling properties for each protrusion, leading to the perception that some protrusions are prone to "unfilled" areas. In such cases, it is preferable to stack the unidirectional prepreg blanks in a manner where the fiber orientation direction of the unidirectional prepreg blank is neither parallel nor perpendicular to the length direction of the protrusion that is considered more difficult to fill. As an example illustrating the difficulty in filling protrusions, the longer the protrusion, the more difficult it is for the prepreg blank to fill. Therefore, it is preferable that the fiber orientation direction of the unidirectional prepreg blank is neither parallel nor perpendicular to the length direction of at least the longest protrusion. It is further preferable that the fiber orientation direction of the unidirectional prepreg blank is neither parallel nor perpendicular to the length direction of all protrusions. The same applies when the protrusions extend along different bidirectional directions, as described above.

[0077] In this invention, it is preferable to set the length of at least a portion of the reinforcing fibers to 10–300 mm. By keeping the fiber length within this range, the reinforcing fibers become easier to conform to the shape of the protrusions in the molded article, thus improving the shape-forming ability towards a three-dimensional form. Furthermore, since the disorder of fiber arrangement during shaping and molding is reduced, fiber-reinforced plastics with small deviations in mechanical properties and high surface smoothness can be obtained.

[0078] Specifically, by setting the fiber length to less than 300 mm, the flexibility and flowability of the fibers are improved, resulting in excellent shapeability and moldability. On the other hand, if the fiber length is set to more than 10 mm, the distance between the cuts makes it difficult for cracks generated when the fiber-reinforced plastic is subjected to high loads to connect, thus resulting in a fiber-reinforced plastic with high mechanical properties and durability.

[0079] It should be noted that when adjusting the fiber length by cutting the reinforcing fibers with a cutting tool, the reinforcing fibers may move when the cutting tool contacts them, potentially resulting in fibers escaping from the cutting tool or being caught in it. Therefore, it is assumed that there are fibers whose lengths are not within the aforementioned range. However, by adjusting the length of most reinforcing fibers to the aforementioned range, a significant improvement can be expected. Furthermore, since fibers may be cut during molding due to contact with the edges of the mold, there may sometimes be fibers shorter than the aforementioned range inside the molded product.

[0080] Regarding the fiber length of the reinforcing fibers, although the fiber length of all the reinforcing fibers in the fiber-reinforced plastic can be adjusted to the aforementioned range, even adjusting only the fiber length of the reinforcing fibers around the protrusions and other parts of the fiber-reinforced plastic that have shape changes can achieve sufficient results.

[0081] As a method of using a unidirectional prepreg blank with reinforcing fibers of 10 to 300 mm in length arranged unidirectionally, which can be used in this invention, for example, it can be (1) impregnating a matrix resin into a reinforcing fiber sheet obtained by spinning discontinuous reinforcing fibers obtained by spinning means such as draw-spinning; it can also be (2) impregnating a matrix resin into a reinforcing fiber sheet obtained by spinning discontinuous reinforcing fibers (e.g., chopped fibers) unidirectionally arranged unidirectionally; or it can also be (3) on the entire surface of a unidirectional prepreg blank composed of continuous reinforcing fibers, for example, Figures 2-6 As shown, insert a continuous or discontinuous finite length cut along the direction of the reinforcing fiber (the cut is inserted into the prepreg blank).

[0082] (1) The so-called draw-cut spinning is a textile method in which tension is applied to continuous fibers in a bundle state, thereby cutting the fibers into short fiber units. It is characterized by the short fiber cutting points not being concentrated in one place but being evenly distributed throughout the entire length of the bundle. It is a method of forming an aggregate by randomly arranging the cut ends of the reinforcing fibers into individual fiber units, rather than aligning them. Although the reinforcing fibers have slightly poorer formability due to flowing in individual fiber units, stress transfer is very efficient, resulting in extremely high mechanical properties. Furthermore, because the cut parts of the reinforcing fibers are dispersed, excellent quality stability can be achieved.

[0083] (2) The method of sheeting discontinuous reinforcing fibers (e.g., chopped fibers) by unidirectional arrangement is to align the cut ends of the reinforcing fibers in multiple fiber units and arrange them in a certain degree of regularity to form an assembly. Since the arrangement and distribution of reinforcing fibers will inevitably be uneven, the quality stability will be slightly worse, but since the flow is in multiple fiber units, excellent formability can be achieved.

[0084] (3) In the method of inserting the prepreg blank with a cut, the quality stability and mechanical properties are excellent because the reinforcing fibers are regularly arranged, and the formability is also excellent because the fibers flow in units of multiple fibers.

[0085] The above three methods (1), (2), and (3) can be appropriately selected according to the application. They are all methods with excellent balance between mechanical properties and formability and can be easily manufactured. However, the method of (3), which involves inserting a continuous or discontinuous finite length cut along the direction of the reinforcing fibers on the entire surface of the unidirectional prepreg blank made of continuous reinforcing fibers, is the most preferred.

[0086] It should be noted that there are no particular limitations on the method of inserting the prepreg blank into the notch. For example, it is feasible to insert the notch manually using a cutter, but it is preferable to use a mechanical method such as an automatic cutting machine that can produce in large quantities and has stable quality. There are no particular limitations on the mechanical method of inserting the notch. For example, methods such as inserting the notch at a predetermined position using a cutting machine that moves a blade on a prepreg blank substrate laid out on a worktable; methods that insert the notch by rotating a perforated rotary cutter in a straight line, or by scanning a pulsed laser used for laser processing at high speed in a straight line, thereby corresponding to the pulse cycle, etc., are all highly productive notch insertion methods and can be selected according to the available production equipment.

[0087] In the prepreg obtained through the above process, multiple discontinuous cuts are provided along the direction that traverses at least a portion of the reinforcing fibers. As a result, the fiber length of at least a portion of the reinforcing fibers is 10 to 300 mm. Moreover, by using the discontinuous cuts, the reinforcing fibers are substantially all cut off, which ensures shapeability and fiber flowability during molding.

[0088] Regarding the length of the slit, when defined as the projected length Ws on the projection plane perpendicular to the reinforcing fiber within the surface of the prepreg substrate, it is preferably in the range of 30 μm to 1.5 mm. However, since the substrate deforms during molding and forming, the slit may become longer where the substrate extends and shorter where the substrate breaks due to compression. Therefore, when observing the molded fiber-reinforced plastic, although there are areas where the slit length is not within the above range, the presence of a structure in which reinforcing fibers with a final fiber length of 10 to 300 mm are regularly arranged in the fiber-reinforced plastic results in a molded product with excellent mechanical properties and surface appearance.

[0089] By reducing Ws, the amount of reinforcing fibers cut by individual slits is reduced, potentially leading to increased strength. In particular, setting Ws to below 1.5 mm can result in significant strength improvements. On the other hand, when Ws is less than 30 μm, it can be difficult to control the slit position, leading to greater deviations in the length of the reinforcing fibers, an increase in reinforcing fibers of length outside the specified range, and decreased shape retention and flowability.

[0090] Here, the term "projection length Ws projected onto a projection plane perpendicular to the reinforcing fiber" refers to... Figure 2 , 4 As shown in Figures 5 and 6, when the cut is inserted into the surface of the prepreg blank, it is assumed that there is a projection plane in a direction perpendicular to the orientation direction of the reinforcing fiber (fiber perpendicular direction 6). This refers to the length when the cut is projected perpendicularly (along the fiber orientation direction 5) onto this projection plane.

[0091] The angle formed by the cut of the prepreg substrate and the reinforcing fiber is set as θ When, preferred θ The absolute value is in the range of 2 to 25°. By making... θ An absolute value of 25° or less can improve mechanical properties, especially tensile strength. From this perspective, a value of 25° or less is preferable. θ The absolute value is less than 15°. On the other hand, if θ If the absolute value of the angle is less than 2°, it can be difficult to insert the blade stably. That is, if the blade becomes horizontal relative to the reinforcing fiber, the reinforcing fiber can easily escape from the tool during insertion, reducing the positional accuracy of the blade. Considering the above, a more preferable approach is... θThe absolute value is 5° or higher.

[0092] As a method for inserting an incision, it is possible to use, for example... Figure 3 As shown, for example, the method of continuous insertion at the aforementioned angle, and as... Figures 4-5 Any of the methods shown can be used to intermittently insert multiple slits. With continuous slits, the fiber length can be kept constant, reducing deviations in mechanical properties and three-dimensional shape conformation. On the other hand, with intermittent slit insertion, by tilting the slit angle relative to the reinforcing fiber, the projected length Ws of the prepreg substrate projected onto the plane perpendicular to the reinforcing fiber can be reduced relative to the actual slit length Y. Therefore, extremely small slits, such as Ws = 1.5 mm or less, can be stably set industrially. Furthermore, compared to continuous slits, the prepreg is less prone to becoming scattered during lamination, resulting in superior workability as a prepreg.

[0093] Preferred cutting patterns for inserting the cut into the prepreg blank, such as Figure 4 As shown, a plurality of discontinuous inclined cuts 9 can be provided in at least a portion of the prepreg substrate along the direction traversing the reinforcing fibers. The plurality of discontinuous inclined cuts 9 are inserted in a straight line to form columns 11, and more preferably, multiple columns 11 are arranged and parallel to each other. By doing so, with the reinforcing fibers of constant length, the distance between adjacent cuts can be maximized, resulting in homogenization of the fiber-reinforced plastic and improved strength. Preferably, the distance X between columns is in the range of, for example, 1 to 5 mm.

[0094] Other preferred cutting patterns for inserting the cut into the prepreg blank include: Figure 5 As shown in the diagram. In this method, at least a portion of the prepreg substrate has a plurality of discontinuous inclined cuts 9 along the direction traversing the reinforcing fibers, and although... θ The absolute value of the inclined cut 9 is essentially the same (uniform), but the angle of the inclined cut 10 is opposite to that of the inclined cut 9. Approximately half of these inclined cuts 9 and 10 are provided. Here, [the text abruptly ends here]. θ The absolute value of "substantially the same" is defined as a deviation within ±1° of the angle. In addition, "approximately half" means that when expressed as a percentage based on the total number of inclined cuts 9 and 10, they are 45% to 55% respectively (the same applies below).

[0095] In addition, such as Figure 5 As shown, when focusing on any one incision A, the incisions closest to incision A are compared to those used as... θ For the closest incision B with the same positive and negative sign, it is closest to the shortest distance from incision A, and θIt is preferable to have four or more implementations with different positive and negative cuts C. When following a three-dimensional shape, for the cut insertion portion of the prepreg blank, the movement of the fiber end is determined by the relationship between the cut angle and the fiber direction. Therefore, by having adjacent cuts with the same shape but opposite angles, isotropy in the plane after molding can be ensured under macroscopic observation.

[0096] When inserting prepreg blanks into a stack, even if the prepreg blanks are in the same fiber direction, the cut direction will differ depending on whether the prepreg blank is viewed from the surface or the back side, if the inclined cut is only in one direction. Therefore, in manufacturing fiber-reinforced plastics, there is a possibility of increased time spent controlling the cut direction to be the same each time, or increased time spent controlling the same number of lamination steps for materials with the same fiber direction but different cut directions. However, if the absolute values ​​of the slope of the cut from the fiber direction are the same, and the cuts at positive angles and negative angles each make up approximately half of the cutting pattern, then lamination can be performed using the same operation as with conventional continuous fiber prepreg blanks.

[0097] Furthermore, as a preferred embodiment for inserting the cut into the prepreg blank, it is also preferable to... Figure 6 As shown, in this method, at least a portion of the prepreg blank is provided with multiple discontinuous inclined cuts 10 along the direction traversing the reinforcing fibers. Furthermore, these discontinuous inclined cuts 10 are inserted in a straight line and of substantially the same length Y, and the shortest distance between adjacent cuts is longer than the length Y of that cut. Here, "substantially the same length" means a difference within ±5% (the same applies hereinafter). From a mechanical point of view, fiber-reinforced plastics fail when cuts, which are points of fiber discontinuity, connect with each other through cracks. By using a cutting pattern where the distance between the cuts is separated within the plane, the effect of at least suppressing crack connection within the same plane is achieved, thus increasing strength.

[0098] Furthermore, as a preferred embodiment of the inserting prepreg blank, a plurality of discontinuous cuts are provided along the direction traversing the reinforcing fibers in at least a portion of the inserting prepreg blank. These discontinuous cuts are inserted in a straight line and of substantially the same length Y, and the distance between adjacent cuts on the same straight line is greater than three times the length Y of the cut. When cuts exist on the same straight line, there is a possibility of damage originating from the cuts occurring along their extension lines, especially as the distance between adjacent cuts increases, making crack formation easier. Therefore, by maximizing the separation of the distance between the same straight-line cuts, crack formation is suppressed, and strength is improved. Moreover, when discontinuous cuts are inserted in the same straight line and the distance between these cuts is close, the cuts are easily identified as a pattern of discontinuous straight lines after molding. On the other hand, by separating the distance between the cuts, they are not identified as a pattern, resulting in a structure with excellent surface quality. It should be noted that 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 cut that is the object is within 2°.

[0099] Furthermore, although all unidirectional prepreg blanks can be made into prepreg blanks with fiber lengths adjusted to the aforementioned range, it is not necessary to arrange the reinforcing fibers of the aforementioned fiber lengths in all layers. In at least one of the unidirectional layers constituting the plate-like portion of the fiber-reinforced plastic, it is sufficient that at least a portion of the reinforcing fibers have a fiber length of 10 to 300 mm. By utilizing the width, height, curvature, and angle of the protrusions of the fiber-reinforced plastic, the layers in which the unidirectional prepreg blanks with adjusted fiber lengths are arranged can be appropriately selected. That is, even if only the fiber lengths of the reinforcing fibers in, for example, the protrusions of the fiber-reinforced plastic and the reinforcing fibers in the layer directly below the protrusions in the plate-like portion are adjusted, sufficient results can be obtained.

[0100] Regarding the fiber area weight (FAW) of at least the plate-like portion of the fiber-reinforced plastic of the present invention, examples include 50 to 1,000 g / m². 2 As an example, but considering deformation resistance and flowability, a value of 50–200 g / m is preferred. 2 Further preferred is 70–200 g / m 2 The optimal value is 70–100 g / m³. 2 The fiber unit area weight of the plate-shaped portion can be mainly controlled by adjusting the fiber unit area weight of the unidirectional prepreg blank constituting it, but when the plate-shaped portion is composed of two or more layers, it is preferable that at least one layer is within the aforementioned range.

[0101] The higher the fiber weight per unit area (FAW), the higher the rigidity of the fiber layer, exceeding 1,000 g / m². 2As deformation resistance increases, fibers struggle to flow into the protrusions (mold recesses), sometimes resulting in "unfilled" or "resin-rich" areas. Furthermore, when using a cutting tool to cut the fiber insertion into a high-weight-per-unit prepreg substrate, an increase in fibers escaping from the tool and the increase in fiber lengths outside the target area can sometimes lead to a prepreg substrate with low flowability. Therefore, prepreg substrates with more layers and lower weight-per-unit prepreg substrates are preferred from a moldability perspective. On the other hand, a fiber weight-per-unit (FAW) of less than 50 g / m² is desirable. 2 In such cases, the cost increases due to the increased production and lamination workload of the prepreg substrate. Furthermore, from the viewpoint of reducing lamination workload, 70 g / m² is more preferable. 2 above.

[0102] Furthermore, it is preferable to arrange the fiber with a unit area weight of 70g / m² on the outermost layer on the protrusion side. 2 Above 100g / m 2 The following is a unidirectional prepreg blank (unidirectional layer). When the outermost layer on the protrusion side has a unidirectional prepreg blank with a fiber area weight, the reinforcing fiber easily follows the shape of the groove forming the protrusion in the mold, and it becomes less likely to produce an excess of resin near the front end of the protrusion ("resin enrichment").

[0103] When stacking two or more unidirectional prepreg preforms, it is preferable to use two or more types of unidirectional prepreg preforms with different fiber unit area weights. In other words, it is also preferable to have two or more unidirectional layers with different fiber unit area weights inside the plate-like portion. In this case, the layers can be stacked in any order, but for example, it is preferable to place a unidirectional prepreg preform with a smaller fiber unit area weight than at least one other unidirectional layer in the plate-like portion on the outermost layer on the side with the protrusion. More specifically, this is achieved by placing a non-flowing, high-fiber-unit-weight unidirectional prepreg preform on the design surface side and a more flowable, low-fiber-unit-weight (e.g., 70 g / m²) unidirectional prepreg preform on the design surface side. 2 Above 100g / m 2 The following unidirectional prepreg blanks are arranged on the protrusion side and molded to obtain a molded product with low fiber mesh twist and high protrusion filling capacity. In addition, when there are protrusions on both sides of the plate-shaped part, by setting the layer near the protrusion with a low fiber unit area weight and the middle layer with a high fiber unit area weight, it is also possible to simultaneously achieve protrusion filling and reduce the amount of lamination work.

[0104] Preferably, the resin mass fraction (Rc) of the molded article (fiber-reinforced plastic) of the present invention is 10-70%. More preferably, it is 20-60%. When the resin mass fraction (Rc) is less than 10%, the amount of resin on the surface of the molded article is small, so the surface of the molded article becomes uneven due to the unevenness of the fibers. Moreover, the flowability of the fibers also decreases, and sometimes "unfilled" products are produced during molding. On the other hand, when the resin mass fraction (Rc) exceeds 70%, there is too much resin, and excess resin is produced in the recesses of the molded article ("resin enrichment"), and sometimes the smoothness of the surface of the molded article decreases due to the curing shrinkage of the resin.

[0105] Preferably, the fiber volume fraction (Vf) of the molded article of the present invention is 43% to 58%. When the fiber volume fraction (Vf) is 43% or higher, the proportion of resin relative to the reinforcing fiber does not become excessive, thus suppressing the formation of local resin enrichment. If resin enrichment exists, there is a possibility that the molding shrinkage rate of that area increases, resulting in surface depressions, which can become the starting point of failure when a load is applied to the molded article, leading to a decrease in strength. Furthermore, the lower the proportion of reinforcing fiber and the higher the proportion of resin in the molded article, the lower the strength, rigidity, and impact resistance of the molded article will be. On the other hand, when it is 58% or lower, the amount of resin covering the reinforcing fiber can be ensured, thus preventing the reinforcing fiber from being exposed on the surface of the molded article and suppressing the formation of unevenness in the design surface and insufficient resin exudation on the surface of the molded article, i.e., "scratches".

[0106] In this invention, the reinforcing fiber is not particularly limited, but glass fiber, aramid fiber, polyethylene fiber, silicon carbide fiber, and carbon fiber are preferred. Especially in obtaining lightweight fiber-reinforced composite materials with high performance and excellent mechanical properties, glass fiber and carbon fiber are preferred. Furthermore, glass fiber or carbon fiber can be used alone, or both can be used simultaneously to balance performance and cost.

[0107] Here, there is no particular limitation on the glass fiber, but E glass fiber, S glass fiber, C glass fiber, and D glass fiber are preferred. From the point of view of balancing cost and strength, E glass fiber is preferred, S glass fiber is preferred when high strength is required, C glass fiber is preferred when acid resistance is required, and D glass fiber is preferred when low dielectric constant is required.

[0108] There is no particular limitation on the average fiber diameter of the glass fiber, but the average fiber diameter is preferably 4 to 20 μm, and more preferably 5 to 16 μm. Generally, a diameter of 4 μm or more can achieve sufficient effect, while an average fiber diameter exceeding 20 μm tends to result in a decrease in strength.

[0109] Furthermore, pretreating glass fibers with coupling agents such as isocyanate compounds, organosilane compounds, organotitanate compounds, organoborane compounds, and epoxy compounds is preferred in terms of obtaining superior mechanical strength.

[0110] There are no particular limitations on the type of carbon fiber, but polyacrylonitrile-based carbon fiber, rayon-based carbon fiber, and pitch-based carbon fiber are preferred. Among these, polyacrylonitrile-based carbon fiber with high tensile strength is particularly preferred. As for the form of carbon fiber, twisted yarn, untwisted yarn, and untwisted yarn can be used.

[0111] Preferably, the tensile modulus of the aforementioned carbon fiber is in the range of 180 to 600 GPa. If the tensile modulus is within this range, the resulting fiber-reinforced plastic can be made rigid, thus enabling the resulting molded article to be lightweight. Furthermore, generally speaking, there is a tendency for the strength of carbon fiber to decrease as the elastic modulus increases, but if it is within this range, the strength of the carbon fiber itself can be maintained. More preferably, the elastic modulus is in the range of 200 to 440 GPa, and even more preferably in the range of 220 to 300 GPa. Any combination of the above upper and lower limits is acceptable. Here, the tensile modulus of the carbon fiber is a value measured according to JIS R7608-2007.

[0112] It should be noted that the following products are examples of commercially available carbon fiber products, but are not specifically 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, and "Torayca (registered trademark)" T1000GB-. The following are examples of trademarks: "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.), and PX35 (manufactured by ZoLTEK Corporation).

[0113] Furthermore, when using a fabric as described later for the fiber-reinforced plastic of the present invention, the number of carbon fiber filaments constituting the fabric is not particularly limited. From the viewpoints of weaving productivity, the required tensile and flexural modulus of elasticity, strength, and designability of the fiber-reinforced plastic, a range of 1,000 to 70,000 filaments is preferred, and more preferably 1,000 to 60,000 filaments. By forming multifilaments by combining multiple filaments, softness can be obtained, and they can be easily deformed into any shape through molding. In addition, for multifilaments, since the shortcomings of a single fiber can be compensated for by other fibers, deviations in the mechanical properties of the molded article can be suppressed, and stable performance can be obtained.

[0114] Next, the matrix resin constituting the fiber-reinforced plastic of the present invention will be described. It is preferable to use a thermosetting resin or a thermoplastic resin as the main component of the matrix resin.

[0115] Here, the thermosetting resin, as the main component of the matrix resin, can be a heat-curing resin or a resin containing a curing agent, a curing accelerator, etc. A resin that forms at least a partial three-dimensional cross-linked structure by inducing a cross-linking reaction with heat is preferred, but there is no particular limitation. Examples of thermosetting resins include epoxy resin compositions, vinyl ester resin compositions, unsaturated polyester resin compositions, polyurethane resin compositions, benzoxazine resin compositions, phenolic resins, urea resin compositions, melamine resin compositions, and polyimide resin compositions, which are preferred from an operability point of view. Among these, epoxy resin compositions, vinyl ester resin compositions, and unsaturated polyester resin compositions are more preferred from the viewpoint of the performance and environmental resistance of fiber-reinforced plastics. Furthermore, the thermosetting resin composition containing these does not need to be a single type; resin compositions can be mixed with each other.

[0116] Furthermore, a matrix resin can be prepared by dispersing the thermoplastic resin as particles or fibers in a thermosetting resin, or by dissolving the thermoplastic resin in a thermosetting resin. For the thermoplastic resin used in this way, it is generally preferred to be a thermoplastic resin having bonds selected from carbon-carbon bonds, amide bonds, imide bonds, ester bonds, ether bonds, carbonate bonds, urethane bonds, thioether bonds, sulfonyl bonds, and carbonyl bonds, even if it partially has a cross-linked structure.

[0117] On the other hand, there is no particular limitation on the thermoplastic resin that is the main component of the matrix resin. From the viewpoints of processability, mechanical properties and design, it is preferable to use a PC / ABS resin obtained by blending 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 acrylonitrile butadiene styrene (ABS) resin.

[0118] Here, when coloring is required as one of the design features of fiber-reinforced plastics, there are no particular restrictions on the color. However, by coloring the aforementioned thermoplastic resins with black, red, yellow, green, blue, purple, brown, etc., the design features can be improved.

[0119] In this invention, non-unidirectional reinforcing fiber sheets, such as fabrics, containing reinforcing fibers can be used together with the aforementioned unidirectional prepreg blanks.

[0120] The aforementioned fibers can be used as reinforcing fibers constituting the non-unidirectional reinforcing fiber sheet, but it is preferable that at least a portion of them include fibers other than thermoplastic resin fibers. When manufacturing the fiber-reinforced plastic of the present invention, heating and pressure molding are performed. However, since thermoplastic resin fibers become soft due to heat, by making at least a portion of the reinforcing fibers constituting the non-unidirectional reinforcing fiber sheet a fiber other than thermoplastic resin fibers, deviations in the thickness and shape of the molded article can be suppressed.

[0121] As a form of non-unidirectional reinforcing fiber sheet, fabric is preferred, for example. Specifically, when the fiber-reinforced plastic of the present invention has protrusions only on one side of the plate-like portion, it is preferably arranged as a fabric as the reinforcing fiber forming the outermost layer on the opposite side. For fabrics woven in with warp and weft yarns, they are used not only because of their excellent mechanical properties and morphological durability, but also to enhance design by revealing the texture of the fabric. It should be noted that the same reinforcing fibers as those in other layers can be used in the fibers constituting the fabric, but different fibers can also be used.

[0122] The weave structure and density of the fabric are not particularly limited and can be arbitrarily chosen from the perspective of fiber-reinforced plastic design. Examples of weave structures include plain weave, twill weave, satin weave, double plain weave, square plain weave, honeycomb weave, float weave, die-cast weave, and crepe weave. Examples of twill weaves include 3-ply twill, 4-ply twill, 5-ply twill, 6-ply twill, stepped twill, curved twill, broken twill, side-ribbed twill, herringbone twill, reed twill, double twill, spiral twill, checkered single-sided twill / twill checkered weave, fancy twill, and shaded twill. Examples of satin weaves include 5-end satin, 7-end satin, 8-end satin, 10-end satin, modified satin, varied satin, reinforced satin, granite weave, satin checkered fabric / satin checkered, and shaded satin. Examples of double plain weaves include warp double plain weave, weft double plain weave, and modified double plain weave. As a planar fabric, examples include regular planar fabric, modified planar fabric, irregular planar fabric, partitioned planar fabric, and triaxial fabric with fibers woven in three directions.

[0123] The reinforcing fibers constituting the fabric can be single glass fibers as exemplified above, or single carbon fibers, or combinations of different glass fibers and carbon fibers. Furthermore, other different reinforcing fibers can be used alone or in combination. In addition, due to its excellent performance, cost, and designability, it is possible to combine at least one type of glass fiber and at least one type of carbon fiber for blending.

[0124] Furthermore, in the outermost layer of fabric, which is formed on the side opposite to the side with the protrusions, it is preferable to pre-impregnate it with a matrix resin. It should be noted that the matrix resin impregnated into the fabric is preferably the same as that used in other layers, but different resins can also be used. When using a resin different from that used in other layers, it is preferable to confirm compatibility and adhesion, and insert an adhesive film or similar material as needed.

[0125] The preferred fiber area weight per unit area of ​​the fabric is 10–300 g / m². 2 More preferably 30–150 g / m 2 The fiber area weight of this fabric is 10 g / m². 2 Under the above conditions, the plastic flow of fibers imparted by the pressure generated during compression molding can be suppressed, and appearance defects such as fiber serpentine and resin enrichment on the surface of the fabric used in the surface layer can be suppressed. Furthermore, the fiber area weight of this fabric is 300 g / m². 2 In the following cases, the material is soft and has excellent shapeability, and when impregnated with epoxy resin compositions or the like during molding, the resin easily reaches the central portion in the thickness direction, leaving little unimpregnated portion (pores). As a result, it becomes a fiber-reinforced plastic exhibiting excellent mechanical properties such as compressive strength.

[0126] Furthermore, regarding the unit area weight of the prepreg preform into which the matrix resin is impregnated in the fabric, when glass fiber or carbon fiber is used as the reinforcing fiber, it is preferably 20 to 400 g / m². 2 More preferably 40–300 g / m 2 The weight per unit area is 20g / m². 2 Under the above conditions, the weaveability becomes good, and the weight per unit area is 400g / m². 2 In the following cases, the fabric is soft and easy to shape. During the impregnation of the matrix resin (such as an epoxy resin composition) during the manufacturing of the prepreg blank and molding, the resin easily reaches the central part in the thickness direction, and it is not easy for unimpregnated parts (pores) to remain. As a result, it becomes a fiber-reinforced plastic exhibiting excellent mechanical properties such as compressive strength.

[0127] Furthermore, when the outermost layer of fabric is disposed on the side opposite to the side with the protrusion, such as Figure 12 As shown, the mesh thickness 107 of the preferred fiber-reinforced plastic fabric 104 is 0.25 mm or less. Here, the mesh thickness of the fabric refers to the thickness of the warp and weft yarns in the woven state (not the thickness of the reinforcing fiber bundles themselves before weaving), and is the length of the warp and weft yarns in the thickness direction of the plate-like portion in their cross-sections. Unlike unidirectional prepregs, in fabrics with woven warp and weft yarns, there is crimp in the reinforcing fiber bundles, and the greater the mesh thickness of the fabric, the greater the crimp. Moreover, the greater the crimp, the easier it is to generate a step difference 108 between the warp and weft yarns. The air contained in the prepreg before molding is squeezed out along with the resin flow by applying pressure during molding. If the step difference between the warp and weft yarns is large, the air remains in the step difference and will remain as air bubbles 109 on the surface of the molded product, sometimes deteriorating the appearance quality of the molded product. When the mesh thickness of the fabric is less than 0.25mm, the step difference between the warp and weft yarns will not become too large, and air bubbles are less likely to form on the surface of the molded product, resulting in a good appearance.

[0128] As a means of adjusting the mesh thickness 107 of the fabric in fiber-reinforced plastics to 0.25 mm or less, for example, a method of molding using a prepreg blank with a thin mesh thickness can be considered. However, when the unidirectional prepreg blank flows into the groove of the mold for forming protrusions during molding, the resin and fiber of the unidirectional prepreg blank are also introduced into the fabric prepreg blank along with the flow of the unidirectional prepreg blank, and sometimes the shape of the fabric mesh changes. Therefore, the mesh thickness of the fabric in the molded product is not determined by the same thickness of the mesh of the fabric prepreg blank used. Here, for example, in terms of materials, it is also preferable to use a unidirectional prepreg blank with inserted slits and a fiber unit area weight of 100 g / m². 2The following methods are employed: using unidirectional prepreg preforms with low unit area weight, or ensuring the fiber direction of the unidirectional prepreg preform is at the lowest possible angle relative to the direction of protrusion extension. By doing so, the filling ability of the unidirectional prepreg preform to the protrusions is improved, resin accumulation at the root of the protrusions is less likely, and the mesh shape of the fabric prepreg preform is less prone to movement. Furthermore, regarding molding conditions, to optimize the resin viscosity of the prepreg preform during the pressing time, it is preferable to set the residual heat time until the prepreg preform is placed in the heated mold and pressurized. Further, to ensure the fabric mesh is less prone to movement and the unidirectional prepreg preform easily fills the grooves of the protrusions, it is preferable to set a temperature difference between the mold on the design surface side and the protrusion side during molding.

[0129] Furthermore, nonwoven fabrics are preferably used as a form of non-unidirectional reinforcing fiber sheet. Nonwoven fabrics are preferably used, for example, inside sheet-like sections where design is not required. Even when nonwoven fabrics are placed inside, the designability of the molded article's surface can be improved.

[0130] The structure and manufacturing method of nonwoven fabrics are not particularly limited. Dry methods, such as carding (where short fibers of a few centimeters are opened and formed into a thin web using a carding machine) or air-forming (where opened short fibers are dispersed by an air random machine and formed into a web on a belt conveyor), are preferred. Furthermore, in the case of nonwoven fabrics manufactured using dry methods, methods that improve the morphological stability of the web by physically interlacing fibers using needle punching, or chemically improving the morphological stability of the web by applying adhesive resins such as unsaturated polyester, polyvinyl alcohol (PVA), or their copolymers using spraying or impregnation, can be used to fix the fibers together. Examples of fiber fixing methods include: blending thermoplastic resin fibers during web manufacturing; and attaching thermoplastic resin particles to the web and then placing the web into a hot roller or oven to melt the thermoplastic resin and fix the fibers together.

[0131] As another example of nonwoven fabric, nonwoven fabrics manufactured using a wet process, in which short fibers are dispersed in water and then scooped onto a papermaking wire, are also preferred. It should be noted that, in order to improve the dimensional stability and workability of nonwoven fabrics manufactured using the wet process in the same way as those manufactured using the dry process, it is also preferable to use a spraying or impregnation method to apply adhesive resins such as unsaturated polyester, polyvinyl alcohol (PVA), or their copolymers to chemically fix the fibers together. During the wire fabric manufacturing process, the fibers are blended with thermoplastic resin, allowing thermoplastic resin particles to adhere to the wire. The wire is then placed in a hot roller or oven to melt the thermoplastic resin, thereby fixing the fibers together.

[0132] As for nonwoven fabrics other than those mentioned above, nonwoven fabrics produced by spunbonding, which involves layering filaments obtained by melt spinning of thermoplastic resin onto a belt conveyor, or by meltblowing, which involves blowing air onto spun filaments to form fine fibers and then accumulating these fibers on a web, are also preferred due to their excellent mechanical properties and low cost.

[0133] The preferred unit area weight of nonwoven fabric is 10–300 g / m². 2 In order to absorb the deformation of the prepreg during molding and mitigate its impact on the surface of the molded article, thickness and strength are required. However, if it becomes too thick, it may affect the physical properties of the molded article. Therefore, a thickness of 30 to 150 g / m² is preferred. 2 The optimal value is 40–100 g / m³. 2 However, by overlapping nonwoven fabrics with low weight per unit area, it is also possible to adjust to the aforementioned range of weight per unit area.

[0134] Furthermore, when the non-unidirectional reinforcing fiber sheet is provided on the surface of the plate-shaped portion, its thickness is preferably 0.01 to 1.0 mm, more preferably 0.05 to 0.5 mm. When the thickness of the non-unidirectional reinforcing fiber sheet is 0.01 mm or more, it is possible to suppress the plastic flow of fibers imparted by the pressure generated during compression molding, and to suppress undesirable appearances such as the serpentine movement of fabric fibers used in the surface of the plate-shaped portion and resin enrichment in the design surface. On the other hand, when the thickness of the non-unidirectional reinforcing fiber sheet is 1.0 mm or less, it is soft and has excellent shapeability, and when impregnated with epoxy resin composition or the like during molding, the resin easily reaches the central part in the thickness direction, and it is not easy for unimpregnated parts (pores) to remain. As a result, it becomes a fiber-reinforced plastic exhibiting excellent mechanical properties such as compressive strength.

[0135] However, when using nonwoven fabric as a non-unidirectional reinforcing fiber sheet, since the thickness of the nonwoven fabric can be adjusted under the pressure during compression molding, a nonwoven fabric with a thickness of 0.01 to 3.0 mm is preferred.

[0136] Next, an example of a method for manufacturing fiber-reinforced plastics according to the present invention will be described in detail, but the present invention is not limited thereto.

[0137] In the case of the fiber-reinforced plastic of the present invention, for example, a unidirectional prepreg blank formed by impregnating a matrix resin with multiple reinforcing fibers can be laminated with the same or different types of unidirectional prepreg blanks, fiber substrates, etc., as needed, and the laminated body can be integrated by heating and pressing as needed through pressure molding, autoclave molding, oven molding, or vacuum oven molding.

[0138] As for molding methods, various molding methods can be mentioned as described above, without particular limitation. However, a preferred method is the pressure molding method, which involves preparing a unidirectional prepreg blank impregnated with a matrix resin, stacking and shaping it as needed, placing it into a mold, and then heating and pressurizing it using a press. As a pressure molding method, by molding under high pressure, the integration of the fiber and the matrix resin is enhanced, and the effects of fiber relaxation and angle deviation can be reduced.

[0139] In pressure molding, the mold cavity (gap) of the die is formed into the desired shape of the fiber-reinforced plastic, and the shape of the die that contacts the protrusions of the fiber-reinforced plastic becomes a recess. As in pressure molding, during thermoforming, the reinforcing fibers and matrix resin can flow into this recess and be molded into the shape of the fiber-reinforced plastic, thus eliminating the need to pre-shape the unidirectional prepreg preform to the same shape as the fiber-reinforced plastic. Therefore, the workload of preform production can be reduced, making it preferable.

[0140] Compared to other molding methods, pressure molding offers superior productivity due to its simplified pre-molding preparation and post-molding processing. Furthermore, when the base resin is a thermosetting resin, demolding can be performed while maintaining a substantially constant mold temperature T. Therefore, since the mold cooling process required when the base resin is a thermoplastic resin is eliminated, high productivity can be achieved simply by combining it with a fast-curing resin.

[0141] It should be noted that the mold temperature T (°C) of the pressure molding is preferably related to the peak heating temperature Tp (°C) of the thermosetting resin based on differential scanning calorimetry (DSC) according to the following formula (I). More preferably, it is ideal to satisfy the following formula (II).

[0142] Tp-60≤T≤Tp+20···(I) Tp-30≤T≤Tp ···(II) When the mold temperature T (°C) is below Tp-60 (°C), the time required for resin curing becomes very long, and sometimes curing is incomplete. On the other hand, when the temperature is above Tp+20 (°C), the rapid reaction of the resin can sometimes cause the formation of pores within the resin, resulting in poor curing. It should be noted that the peak heating temperature Tp (°C) based on DSC is a value measured under a heating rate of 10°C / min.

[0143] The fiber-reinforced plastic of the present invention is preferably manufactured under conditions where the minimum viscosity of the thermosetting resin used as the matrix resin, based on dynamic viscoelasticity (DMA) measurement, is 0.1 to 100 Pa·s. More preferably, it is 0.5 to 10 Pa·s. When the minimum viscosity is less than 0.1 Pa·s, only the resin flows under pressure, and sometimes the reinforcing fibers cannot be adequately filled to the tip of the protrusion. On the other hand, when it is greater than 100 Pa·s, due to insufficient resin flowability, sometimes the reinforcing fibers and resin cannot be adequately filled to the tip of the protrusion. It should be noted that the minimum viscosity based on DMA is a value measured under conditions where the heating rate is 1.5 °C / min.

[0144] Furthermore, in this invention, firstly, a unidirectional prepreg blank, formed by impregnating a matrix resin with multiple reinforcing fibers, is laminated together with the same or different types of unidirectional prepreg blanks, non-unidirectional reinforcing fiber sheets, or other fiber substrates to form a preform. The preform is then placed in a preheated mold (e.g., a concave mold), and the mold is closed and pressure is applied, thereby obtaining a fiber-reinforced plastic with a shape having a plate-like portion and at least one protrusion raised from at least one side of the plate-like portion. In this case, it is preferable that the fiber orientation direction of at least one layer of unidirectional prepreg blank in the preform is neither parallel nor perpendicular to the length direction of the protrusion (becoming neither parallel nor perpendicular).

[0145] It should be noted that in this invention, the required number of unidirectional prepreg blanks can be stacked according to the desired thickness of the fiber-reinforced plastic. In this case, it is preferable that the fiber orientation direction of all unidirectional prepreg blanks is neither parallel nor perpendicular to the width direction (length direction) in the cross-section of the protrusion.

[0146] Furthermore, as described above, when combining unidirectional prepreg blanks with other unidirectional prepreg blanks, non-unidirectional reinforcing fiber sheets, or fiber substrates, it is preferable to place non-unidirectional reinforcing fiber sheets in layers from the second layer onwards from the surface of the preform (i.e., layers other than the outermost layer on the side where the protrusions are provided). In particular, when a non-unidirectional reinforcing fiber sheet in the form of a fabric is placed in the outermost layer opposite to the side where the protrusions are provided, plastic flow of fibers caused by pressure during compression molding can be suppressed, and appearance defects such as fiber serpentine and resin enrichment on the designed surface of the fabric used in the surface layer can be suppressed.

[0147] Non-unidirectional reinforced fiber sheets can be dry sheets without matrix resin, or sheets in the form of prepreg blanks formed by impregnating at least a portion of the matrix resin.

[0148] When the non-unidirectional fiber reinforced sheet is a prepreg blank, the matrix resin pre-impregnated into the non-unidirectional fiber reinforced sheet is preferably the same resin as other prepreg blanks, but from the viewpoint of adhesion and formability, the preferred resin can be arbitrarily selected.

[0149] Furthermore, when the non-unidirectional fiber-reinforced sheet is a prepreg blank, it is preferable that the fiber volume fraction Vf[a] of the non-unidirectional fiber-reinforced sheet and the fiber volume fraction Vf[b] of the aforementioned unidirectional prepreg blank have a relationship of Vf[a] > Vf[b]. In this case, during compression molding, there is room for the matrix resin contained in the unidirectional prepreg blank to impregnate the non-unidirectional fiber-reinforced sheet. That is, by applying pressure during compression molding, the resin contained in the unidirectional prepreg blank is impregnated into the resin-unimpregnated portion of the non-unidirectional fiber-reinforced sheet, thereby obtaining a molded article that is fully filled with resin, for example, a fiber-reinforced plastic with excellent mechanical properties and a porosity of less than 2% can be obtained.

[0150] Furthermore, Vf[a] is preferably 55-99.9%, more preferably 80-99%. When Vf[a] is 55% or more, it is less affected by the resin flow caused by the pressure during compression molding, and the fiber flow can be suppressed. Therefore, fiber-reinforced plastics with excellent appearance quality, less fiber disorder, and less surface unevenness can be obtained.

[0151] Example The present invention will be further illustrated below using examples and comparative examples, but the invention is not specifically limited thereto. The conditions and results are shown in Tables 1 to 4.

[0152] <Painting treatment of the designed surfaces of molded parts> Apply filler (Mikuni PaintCo., Ltd. Romen Filler Black 9-7606) to the side of the molded part opposite to the side with the protrusion (design side). After it dries completely, sand the surface with #400 sandpaper and apply primer (Origin Co., Ltd. Origin Primer U-03). Then, apply two coats of coating agent (OriginCo., Ltd. Planet HS) using a spray gun.

[0153] <Appearance Quality: Rib Inspection on Design Surfaces> In the design surfaces of the molded articles before and after painting, a phenomenon known as "ribs" was identified, which is a deformation caused by a disruption in the fiber orientation due to a depression directly below the protrusion. Specifically, with the protrusion facing down, the upper part of the plate was held under a fluorescent lamp (1200 lx (lux)) and the side opposite to the side with the protrusion was visually observed before and after painting using the method described in the above-mentioned <Painting Treatment of the Design Surfaces of Molded Articles>.

[0154] At this point, rotate the molded part 360° horizontally, and further observe it while tilting it vertically at an angle of 0° to 60°, checking along the ribs to confirm whether the reflected light from the fluorescent lamp is deformed. As a result, the following cases are categorized: "A" represents the case where there is no deformation or dent at any angle under uncoated conditions; "B" represents the case where there is deformation only at a constant angle before coating, but no deformation or dent at any angle after coating; "C" represents the case where there is deformation only at a constant angle after coating, but no dent; and "D" represents the case where there is deformation or dent at any angle after coating.

[0155] <Appearance Quality: Scratch Inspection on Design Surfaces> In the design surface of the molded part before painting, identify the phenomenon of "scratches" where fibers are exposed due to insufficient resin exudation. Specifically, hold the upper part of the plate with the protrusion facing down, and under a fluorescent lamp (illuminance 1200 lx (lux)), visually observe the side of the plate-shaped part opposite to the side with the protrusion (design surface) in the pre-painting stage.

[0156] At this point, rotate the molded part 360° in the horizontal direction, and further observe it while tilting it at an angle of 0° to 60° in the vertical direction. The case where there are no scratches on the entire design surface at any angle is designated as "A", the case where scratches can be partially observed only at a certain constant angle but can be hidden by painting is designated as "B", and the case where scratches can be observed on the entire design surface and therefore cannot withstand painting is designated as "C".

[0157] <Appearance Quality: Bubble Inspection on Fabric Design Surfaces> Before painting, check the presence or absence of air bubbles on the design surface of the molded part. Specifically, hold the upper part of the board with the protrusion facing down, and under a fluorescent lamp (illuminance 1200 lx (lux)), visually observe the side of the board opposite to the side with the protrusion (the fabric design surface) before painting.

[0158] At this point, rotate the molded product 360° horizontally, and further observe it while tilting it vertically at an angle of 0° to 60°, counting the number of bubbles that can be visually identified. On the entire fabric design surface, the case with 3 or fewer bubbles is designated as "A", and the case without such bubbles is designated as "B".

[0159] <Determination of the mesh thickness of fabric in the cross-section of molded articles> The protrusions, including the plate-like portion, are cut out using a disc mill. After grinding the cut surface, it is observed using a microscope (Keyence Corporation, VHX-6000) to measure the thickness of the fabric mesh. It should be noted that the mesh thickness in a cross-sectional image observed under the microscope may vary slightly depending on the specific mesh size being measured; however, the mesh thickness with the largest measured thickness is recorded as the mesh thickness of the fabric in that molded product.

[0160] <Inspection of resin enrichment in the cross-section of the protrusion> The protrusion, including the plate-like portion, was cut out using a disc grinder. After grinding the cut surface, it was observed using a microscope (Keyence Corporation, VHX-6000) to confirm the presence or absence of resin enrichment. In the cross-sectional image, a case where the area of ​​resin enrichment is less than 3% relative to the combined area of ​​the protrusion and the plate-like portion directly below it was designated as "A"; a case where the area is 3% or more but less than 5% was designated as "B"; and a case where the area is 5% or more was designated as "C". However, if there are multiple areas of resin enrichment, the area with the largest area is used for determination.

[0161] <Determination of the maximum width w of the protrusion and the total thickness t' of the unidirectional layer inside the plate-like portion (the unidirectional layer located on the protrusion side compared to the non-unidirectional layer)> The protrusion is cut out using a disc grinder in a manner that includes a plate-like portion. After grinding the cut surface, the cut surface is observed using a microscope (VHX-6000 manufactured by Keyence Corporation). The maximum width w of the protrusion and the total thickness t' of the unidirectional layer inside the plate-like portion (the unidirectional layer located on the protrusion side compared to the non-unidirectional layer) are calculated based on the captured image.

[0162] <Determination of the thickness t of the plate-like portion> The thickness of the plate-like portion on the left and right of each protrusion is measured using a micrometer, and the smaller value is set as the thickness t of the plate-like portion.

[0163] <Determination of the radius of curvature R of the junction between the protrusion and the plate> Use a radius gauge to measure the radius of curvature of the surface formed by the plate-like part and the protrusion on both sides of the protrusion, and set the larger one as the radius of curvature R.

[0164] <Determination of fiber volume content (Vf)> The specific gravity of the molded article was determined using a hydrometer based on the water displacement method (ALFA MIRAGE, ELECTRONIC DENSIMETERSD-200L). Next, using the specific gravity of the obtained molded article, the specific gravity of the reinforcing fibers in the prepreg used, and the specific gravity of the matrix resin, the fiber volume content was calculated using the following formula.

[0165] Fiber volume content (Vf) (%) = (specific gravity of molded product - specific gravity of resin) / (specific gravity of reinforcing fiber - specific gravity of resin) × 100.

[0166] [Example 1] Unidirectional prepreg blank #P384-S-10 (carbon fiber (4,900MPa, tensile modulus 235GPa), FAW=100g / m) manufactured by Toray Industries, Inc. 2 (Thermosetting epoxy resin, Rc=40%), cut 4 pieces from a 100mm×100mm prepreg substrate. Stack them in a manner that is [+45 / -45]2 to prepare a prepreg substrate laminate (preform).

[0167] Next, prepare a 100mm×100mm concave mold as the lower mold. In addition, prepare a convex mold with a groove (rib groove, maximum width 1.5mm, front end width 1.0mm, radius of curvature 0.2mm, depth 3mm, length 60mm) for forming protrusions (ribs) in the center of the 100mm×100mm convex part as the upper mold, and heat it to 150℃.

[0168] The pre-prepared prepreg substrate laminate is housed in the lower mold in such a way that the 0° direction during lamination is parallel to the rib groove. After the upper mold is installed on the lower mold, the molding and heating curing of the matrix resin are carried out using a heated pressure molding machine under the conditions of 12MPa pressure, 150℃ heating temperature and 3 minutes of pressing time, to obtain ribbed fiber reinforced plastic.

[0169] The obtained fiber-reinforced plastic has a rib in the center of a 100mm × 100mm plate-shaped portion, with carbon fiber filling to the front end of the rib in visual observation. Measurements were performed using the methods described in <Measurement of the maximum width w of the protrusion and the total thickness t' of the unidirectional layer inside the plate-shaped portion (the unidirectional layer located on the protrusion side compared to the non-unidirectional layer)>, <Measurement of the thickness t of the plate-shaped portion>, and <Measurement of the radius of curvature R of the joint between the protrusion and the plate-shaped portion>. The results showed that the maximum width w of the protrusion was 1.5mm, the radius of curvature R of the surface formed by the protrusion and the plate-shaped portion was 0.2mm, the thickness t of the plate-shaped portion was 0.3mm, and w / t was 5. Furthermore, since the plate-shaped portion is entirely formed of unidirectional layers, t = t' in this molded body.

[0170] The obtained molded product was inspected using the method described in "Appearance Quality: Rib Inspection of Design Surfaces". As a result, under uncoated conditions, the reflected light from the fluorescent lamp did not deform at any angle.

[0171] Furthermore, when inspected using the methods described in "Appearance Quality: Scratch Inspection of Design Surfaces", it was found that scratches could only be partially observed at a certain constant angle, but could be concealed by painting.

[0172] Furthermore, the determination was performed using the method described in "Determination of Fiber Volume Content (Vf)", and the result was Vf = 60%.

[0173] [Example 2] according to Figure 6 The cutting pattern is designed to achieve a fiber length of 13mm, a cut width Ws=0.25mm, and a cut angle of... θ In a manner of ±14°, a roller cutter equipped with a tool on the barrel is pressed against a unidirectional prepreg blank P384-S-10 manufactured by Toray Industries, Ltd., thereby inserting a cut into the reinforcing fiber of the prepreg blank, resulting in a cut-inserted prepreg blank.

[0174] Insert the prepreg blank through the cut, and cut four pieces from a single 100mm × 100mm prepreg substrate. Stack these four pieces in a configuration of [+45 / -45]² to prepare a prepreg substrate laminate. Using this prepreg substrate laminate, mold it under the same conditions as in Example 1 to obtain a fiber-reinforced plastic.

[0175] The obtained fiber-reinforced plastic has a rib in the center of a 100mm × 100mm × plate-like portion, with carbon fibers filling the front end of the rib during visual observation. Measurements were performed similarly to those in Example 1. The results showed that the maximum width w of the protrusion was 1.5mm, the radius of curvature R of the surface formed by the protrusion and the plate-like portion was 0.2mm, the thickness t of the plate-like portion was 0.3mm, and w / t was 5. Furthermore, the plate-like portion was entirely formed of a unidirectional layer; therefore, in this molded body, t = t'.

[0176] Similar to Example 1, the inspection was carried out using the method described in "Appearance Quality: Rib Inspection of Design Surfaces". As a result, under uncoated conditions, the reflected light from the fluorescent lamp did not deform at any angle.

[0177] Furthermore, when inspected using the methods described in "Appearance Quality: Scratch Inspection of Design Surfaces", it was found that scratches could only be partially observed at a certain constant angle, but could be concealed by painting.

[0178] Furthermore, the determination was performed using the method described in "Determination of Fiber Volume Content (Vf)", and the result was Vf = 60%.

[0179] Furthermore, the method described in "Inspection of Resin Accumulation in the Protrusion Section" was used for inspection, and the result showed that the area of ​​resin accumulation was less than 3% relative to the combined area of ​​the protrusion and the plate-like portion directly below the protrusion.

[0180] [Example 3] The prepreg blank was inserted through a notch similar to that in Example 2. Eight pieces of a 100mm × 100mm prepreg blank substrate were cut out and stacked in a configuration of [+45 / -45]4. A straight-line mold with a rib groove for forming the protrusions (ribs) having a maximum width of 2.0mm, a front end width of 1.0mm, a radius of curvature of 0.5mm, a depth of 3mm, and a length of 60mm was used. Otherwise, the prepreg blank substrate stack was press-molded under the same conditions as in Example 1 to obtain fiber-reinforced plastic.

[0181] The obtained fiber-reinforced plastic has a rib in the center of a 100mm × 100mm plate-like portion, with carbon fibers filling the front end of the rib during visual observation. Measurements were performed similarly to those in Example 1. The results showed that the maximum width w of the protrusion was 2.0mm, the radius of curvature R of the surface formed by the protrusion and the plate-like portion was 0.5mm, the thickness t of the plate-like portion was 0.7mm, and w / t was 3. Furthermore, since the plate-like portion was entirely formed of a unidirectional layer, t = t' in this molded body.

[0182] Similar to Example 1, the inspection was carried out using the method described in "Appearance Quality: Rib Inspection of Design Surfaces". As a result, under uncoated conditions, the reflected light from the fluorescent lamp did not deform at any angle.

[0183] Furthermore, when inspected using the methods described in "Appearance Quality: Scratch Inspection of Design Surfaces", it was found that scratches could only be partially observed at a certain constant angle, but could be concealed by painting.

[0184] Furthermore, the determination was performed using the method described in "Determination of Fiber Volume Content (Vf)", and the result was Vf = 60%.

[0185] [Example 4] A prepreg blank with slits inserted in the same manner as in Example 2 was inserted. Six pieces of a 100mm × 100mm prepreg blank substrate were cut out and stacked in a configuration of [+45 / -45]3. A straight-line mold with a rib groove for forming the protrusions (ribs) having a maximum width of 5.0mm, a front end width of 1.0mm, a radius of curvature of 1.0mm, a depth of 3mm, and a length of 60mm was used. Otherwise, the prepreg blank substrate laminate was press-molded under the same conditions as in Example 1 to obtain fiber-reinforced plastic.

[0186] The obtained fiber-reinforced plastic has a rib in the center of a 100mm × 100mm plate-like portion, with carbon fibers filling the front end of the rib during visual observation. Measurements were performed similarly to those in Example 1. The results showed that the maximum width w of the protrusion was 5.0mm, the radius of curvature R of the surface formed by the protrusion and the plate-like portion was 1.0mm, the thickness t of the plate-like portion was 0.5mm, and w / t was 10. Furthermore, since the plate-like portion was entirely formed of a unidirectional layer, t = t' in this molded body.

[0187] The same inspection was performed as in Example 1. The results showed that before coating, the reflected light from the fluorescent lamp was deformed only at a certain constant angle, but after coating, there was no deformation at any angle.

[0188] Furthermore, when inspected using the methods described in "Appearance Quality: Scratch Inspection of Design Surfaces", it was found that scratches could only be partially observed at a certain constant angle, but could be concealed by painting.

[0189] Furthermore, the determination was performed using the method described in "Determination of Fiber Volume Content (Vf)", and the result was Vf = 60%.

[0190] [Example 5] Insert the prepreg blank through the same slits as in Example 2, and cut four pieces (fiber unit area weight 100g / m²) from a single 100mm × 100mm prepreg blank substrate. 2 Furthermore, similar to Example 2, a unidirectional prepreg blank P384-S-20 (carbon fiber (4,900 MPa, tensile modulus 235 GPa), FAW=200 g / m²) was prepared at Toray Industries, Inc. 2 (Thermosetting epoxy resin, Rc=40%) Insert the incision and cut out one piece of prepreg substrate (fiber unit area weight 200g / m²) in a 100mm×100mm format. 2 ). It is composed of layers to form [(fiber unit area weight 200g / m²)] 2 +45][(Fiber unit area weight 100g / m²) 2 The prepreg substrate laminate is prepared by laminating the substrates in the manner of )-45 / +45]2.

[0191] Using this prepreg substrate laminate, the fiber unit area weight is 200 g / m². 2 The prepreg blank is molded in the same mold and under the same conditions as in Example 4 to obtain fiber-reinforced plastic.

[0192] The obtained fiber-reinforced plastic has a rib in the center of a 100mm × 100mm plate-like portion, with carbon fibers filling the front end of the rib during visual observation. Measurements were performed similarly to those in Example 1. The results showed that the maximum width w of the protrusion was 5.0mm, the radius of curvature R of the surface formed by the protrusion and the plate-like portion was 1.0mm, the thickness t of the plate-like portion was 0.5mm, and w / t was 10. Furthermore, since the plate-like portion was entirely formed of a unidirectional layer, t = t' in this molded body.

[0193] The same test was performed as in Example 1, and the results showed that, under uncoated conditions, the reflected light from the fluorescent lamp did not deform at any angle.

[0194] Furthermore, when inspected using the methods described in "Appearance Quality: Scratch Inspection of Design Surfaces", it was found that scratches could only be partially observed at a certain constant angle, but could be concealed by painting.

[0195] Furthermore, the determination was performed using the method described in "Determination of Fiber Volume Content (Vf)", and the result was Vf = 60%.

[0196] [Example 6] Insert the prepreg blank through the same notch as in Example 2. Cut six pieces from a 100mm × 100mm prepreg blank substrate and stack them in a configuration of [+45 / -45]3. Place a resin-unimpregnated glass mat (60g / m²) between the first and second layers. 2 The glass mat is arranged in the lower mold as the second layer from the bottom, and molded under the same mold and conditions as in Example 4 to obtain fiber-reinforced plastic.

[0197] The obtained fiber-reinforced plastic has a rib in the center of a 100mm × 100mm plate-like portion, with carbon fibers filling the front end of the rib in visual observation. Measurements were performed similarly to those in Example 1. The results showed that the maximum width w of the protrusion was 5.0mm, the radius of curvature R of the surface formed by the protrusion and the plate-like portion was 1.0mm, the thickness t of the plate-like portion was 0.5mm, and the w / t ratio was 10. Furthermore, the total thickness t' of the unidirectional layer on the protrusion side compared to the glass mat was 0.4mm, and the w / t' ratio was 13.

[0198] The same test was performed as in Example 1, and the results showed that, under uncoated conditions, the reflected light from the fluorescent lamp did not deform at any angle.

[0199] Furthermore, the inspection was conducted using the methods described in "Appearance Quality: Scratch Inspection of Design Surfaces," and the results showed that scratches were visible throughout the design surface, indicating that the surface could not withstand painting.

[0200] Furthermore, the determination was performed using the method described in "Determination of Fiber Volume Content (Vf)", and the result was Vf was 64%.

[0201] [Example 7] A prepreg blank with slits inserted in the same manner as in Example 2 was inserted. Nineteen pieces of a 100mm × 100mm prepreg blank substrate were cut out and stacked in a configuration of [+45 / -45]9[+45]. A straight-line mold with a rib groove for forming the protrusions (ribs) having a maximum width of 8.0mm, a front end width of 1.0mm, a radius of curvature of 2.0mm, a depth of 3mm, and a length of 60mm was used. Otherwise, the prepreg blank substrate stack was press-molded under the same conditions as in Example 1 to obtain fiber-reinforced plastic.

[0202] The obtained fiber-reinforced plastic has a rib in the center of a 100mm × 100mm plate-like portion, with carbon fibers filling the front end of the rib during visual observation. Measurements were performed similarly to those in Example 1. The results showed that the maximum width w of the protrusion was 8.0mm, the radius of curvature R of the surface formed by the protrusion and the plate-like portion was 2.0mm, the thickness t of the plate-like portion was 1.8mm, and w / t was 4. Furthermore, since the plate-like portion was entirely formed of a unidirectional layer, t = t' in this molded body.

[0203] The same test was performed as in Example 1, and the results showed that, under uncoated conditions, the reflected light from the fluorescent lamp did not deform at any angle.

[0204] Furthermore, when inspected using the methods described in "Appearance Quality: Scratch Inspection of Design Surfaces", it was found that scratches could only be partially observed at a certain constant angle, but could be concealed by painting.

[0205] Furthermore, the determination was performed using the method described in "Determination of Fiber Volume Content (Vf)", and the result was Vf was 59%.

[0206] [Example 8] A prepreg blank, with the same slits inserted as in Example 2, is inserted. Four pieces of a 100mm × 100mm prepreg blank substrate are cut out and stacked in a configuration of [+45 / -45]2. The prepreg blank substrate stack is then press-formed under the same mold and conditions as in Example 7 to obtain fiber-reinforced plastic.

[0207] The obtained fiber-reinforced plastic has a rib in the center of a 100mm × 100mm plate-like portion, with carbon fibers filling the front end of the rib during visual observation. Measurements were performed similarly to those in Example 1. The results showed that the maximum width w of the protrusion was 8.0mm, the radius of curvature R of the surface formed by the protrusion and the plate-like portion was 2.0mm, the thickness t of the plate-like portion was 0.3mm, and w / t was 27. Furthermore, since the plate-like portion was entirely formed of a unidirectional layer, t = t' in this molded body.

[0208] The same inspection was performed as in Example 1. The results showed that before coating, reflected light was deformed at any angle, but after coating, there was only deformation at a certain constant angle without any dents.

[0209] Furthermore, when inspected using the methods described in "Appearance Quality: Scratch Inspection of Design Surfaces", it was found that scratches could only be partially observed at a certain constant angle, but could be concealed by painting.

[0210] Furthermore, the determination was performed using the method described in "Determination of Fiber Volume Content (Vf)", and the result was Vf = 60%.

[0211] [Example 9] Using the same slits inserted as in Example 2, eleven pieces of a 100mm × 100mm prepreg substrate were cut from one prepreg substrate and stacked in a configuration of [+45 / -45]5[+45]. At the bottom, as the design substrate, a fabric prepreg (#CO6343B carbon fiber with a tensile strength of 3,530 MPa, a tensile modulus of elasticity of 230 GPa, and a basis weight of 198 g / m²) manufactured by Toray Industries, Inc. was placed. 2 The prepreg substrate laminate is press-molded under the same mold and conditions as in Example 7, with the prepreg fabric blank as the lower mold side, to obtain fiber-reinforced plastic.

[0212] The obtained fiber-reinforced plastic has a rib in the center of a 100mm × 100mm plate-like portion, with carbon fibers filling the front end of the rib in visual observation. Measurements were performed similarly to those in Example 1. The results showed that the maximum width w of the protrusion was 8.0mm, the radius of curvature R of the surface formed by the protrusion and the plate-like portion was 2.0mm, the thickness t of the plate-like portion was 1.2mm, and the w / t ratio was 7. Furthermore, compared to the non-unidirectional layer, the total thickness t' of the unidirectional layer located on the protrusion side was 1.0mm, and the w / t' ratio was 8.

[0213] The same test was performed as in Example 1, and the results showed that, under uncoated conditions, the reflected light from the fluorescent lamp did not deform at any angle.

[0214] Furthermore, when inspected using the methods described in "Appearance Quality: Scratch Inspection of Design Surfaces", it was found that scratches could only be partially observed at a certain constant angle, but could be concealed by painting.

[0215] Furthermore, the determination was performed using the method described in "Determination of Fiber Volume Content (Vf)", and the result was Vf = 61%.

[0216] The inspection of "Appearance Quality: Bubble Inspection on Fabric Design Surface" revealed that 10 bubbles could be visually confirmed.

[0217] In addition, the thickness of the mesh of the fabric in the cross-section of the molded article was measured, and the result was that the thickness of the mesh was 0.28 mm.

[0218] [Example 10] Nine prepreg blanks, each 100mm × 100mm in size, were cut from a prepreg blank substrate using the same slits as in Example 2. These nine blanks were then stacked in a configuration of [+45 / -45]4[+45]. The prepreg blank substrate stack was then press-formed under the same mold and conditions as in Example 7 to obtain fiber-reinforced plastic.

[0219] The obtained fiber-reinforced plastic has a rib in the center of a 100mm × 100mm plate-like portion, with carbon fibers filling the front end of the rib during visual observation. Measurements were performed similarly to those in Example 1. The results showed that the maximum width w of the protrusion was 8.0mm, the radius of curvature R of the surface formed by the protrusion and the plate-like portion was 2.0mm, the thickness t of the plate-like portion was 0.8mm, and w / t was 10. Furthermore, since the plate-like portion was entirely formed of a unidirectional layer, t = t' in this molded body.

[0220] The same inspection was performed as in Example 1. The results showed that before coating, the reflected light from the fluorescent lamp was deformed only at a certain constant angle, but after coating, there was no deformation at any angle.

[0221] Furthermore, when inspected using the methods described in "Appearance Quality: Scratch Inspection of Design Surfaces", it was found that scratches could only be partially observed at a certain constant angle, but could be concealed by painting.

[0222] Furthermore, the determination was performed using the method described in "Determination of Fiber Volume Content (Vf)", and the result was Vf = 60%.

[0223] [Example 11] Nine prepreg blanks, each 100mm x 100mm in size, were cut from a prepreg blank substrate and stacked in a configuration of [+45 / -45]4[+45]. A straight-line mold with a rib groove for forming the protrusions (ribs) having a maximum width of 9.0mm, a front end width of 1.0mm, a radius of curvature of 3.0mm, a depth of 3mm, and a length of 60mm was used. Otherwise, the prepreg blank substrate stack was press-molded under the same conditions as in Example 1 to obtain fiber-reinforced plastic.

[0224] The obtained fiber-reinforced plastic has a rib in the center of a 100mm × 100mm plate-like portion, with carbon fibers filling the front end of the rib during visual observation. Measurements were performed similarly to those in Example 1. The results showed that the maximum width w of the protrusion was 9.0mm, the radius of curvature R of the surface formed by the protrusion and the plate-like portion was 3.0mm, the thickness t of the plate-like portion was 0.8mm, and w / t was 11. Furthermore, since the plate-like portion was entirely formed of a unidirectional layer, t = t' in this molded body.

[0225] The same inspection was performed as in Example 1. The results showed that before coating, reflected light was deformed at any angle, but after coating, there was only deformation at a certain constant angle without any dents.

[0226] Furthermore, when inspected using the methods described in "Appearance Quality: Scratch Inspection of Design Surfaces", it was found that scratches could only be partially observed at a certain constant angle, but could be concealed by painting.

[0227] Furthermore, the determination was performed using the method described in "Determination of Fiber Volume Content (Vf)", and the result was Vf = 60%.

[0228] [Example 12] A prepreg blank with slits inserted in the same manner as in Example 2 was inserted. Nineteen pieces of a 100mm × 100mm prepreg blank substrate were cut out and stacked in a configuration of [+45 / -45]9[+45]. A straight-line mold with a rib groove for forming the protrusions (ribs) having a maximum width of 0.9mm, a front end width of 0.4mm, a radius of curvature of 0.2mm, a depth of 3mm, and a length of 60mm was used. Otherwise, the prepreg blank substrate stack was press-molded under the same conditions as in Example 1 to obtain fiber-reinforced plastic.

[0229] The obtained fiber-reinforced plastic has a rib in the center of a 100mm × 100mm plate-like portion, with carbon fibers filling the front end of the rib during visual observation. Measurements were performed similarly to those in Example 1. The results showed that the maximum width w of the protrusion was 0.9mm, the radius of curvature R of the surface formed by the protrusion and the plate-like portion was 0.2mm, the thickness t of the plate-like portion was 1.8mm, and w / t was 0.5. Furthermore, since the plate-like portion was entirely formed of a unidirectional layer, t = t' in this molded body.

[0230] The same test was performed as in Example 1, and the results showed that, under uncoated conditions, the reflected light from the fluorescent lamp did not deform at any angle.

[0231] Furthermore, when inspected using the methods described in "Appearance Quality: Scratch Inspection of Design Surfaces", it was found that scratches could only be partially observed at a certain constant angle, but could be concealed by painting.

[0232] Furthermore, the determination was performed using the method described in "Determination of Fiber Volume Content (Vf)", and the result was Vf was 59%.

[0233] [Example 13] Insert the prepreg blank through the same slit as in Example 2, and cut two pieces (fiber unit area weight 100g / m²) from one 100mm × 100mm prepreg blank substrate. 2 Furthermore, similar to Example 2, a unidirectional prepreg blank P384-S-20 (carbon fiber (4,900 MPa, tensile modulus 235 GPa), FAW=200 g / m²) was prepared at Toray Industries, Inc.2 (Thermosetting epoxy resin, Rc=40%) Insert the incision and cut out one piece of prepreg substrate (fiber unit area weight 200g / m²) in a 100mm×100mm format. 2 ). It is composed of layers to form [(fiber unit area weight 100g / m²)] 2 +45 / -45][(fiber unit area weight 200g / m²) 2 The prepreg substrate laminate is prepared by laminating the prepreg substrate in the manner of [+45].

[0234] Using this prepreg substrate laminate, the fiber unit area weight is 100g / m² 2 The prepreg blank is molded in the same mold and under the same conditions as in Example 2, with the lower mold side as the prepreg blank, to obtain fiber reinforced plastic.

[0235] The obtained fiber-reinforced plastic has a rib in the center of a 100mm × 100mm plate-like portion, with carbon fibers filling to the front end of the rib during visual observation. Measurements were performed similarly to those in Example 1. The results showed that the maximum width w of the protrusion was 1.5mm, the radius of curvature R of the surface formed by the protrusion and the plate-like portion was 0.2mm, the thickness t of the plate-like portion was 0.3mm, and w / t was 5. Furthermore, the plate-like portion was entirely formed of a unidirectional layer; therefore, in this molded body, t = t'.

[0236] The same test was performed as in Example 1, and the results showed that, under uncoated conditions, the reflected light from the fluorescent lamp did not deform at any angle.

[0237] Furthermore, when inspected using the methods described in "Appearance Quality: Scratch Inspection of Design Surfaces", it was found that scratches could only be partially observed at a certain constant angle, but could be concealed by painting.

[0238] Furthermore, the determination was performed using the method described in "Determination of Fiber Volume Content (Vf)", and the result was Vf = 60%.

[0239] Furthermore, the method described in "Inspection of Resin Accumulation in the Cross Section of the Protrusion" was used for inspection, and the result showed that the area of ​​resin accumulation was more than 5% relative to the combined area of ​​the protrusion and the plate-like portion directly below the protrusion.

[0240] [Example 14] Similar to Example 2, a unidirectional prepreg blank #P384-S-10 (carbon fiber (4,900 MPa, tensile modulus 235 GPa), FAW=100 g / m²) was prepared at Toray Industries, Inc. 2A thermosetting epoxy resin (Rc=42%) was inserted through a notch. A prepreg blank was inserted through this notch, and four pieces of a 100mm × 100mm prepreg substrate were cut and stacked in a configuration of [+45 / -45]² to prepare a prepreg substrate laminate. Using this prepreg substrate laminate, a pressure of 6MPa was applied, and molding was performed under the same mold and conditions as in Example 2 to obtain a fiber-reinforced plastic.

[0241] The obtained fiber-reinforced plastic has a rib in the center of a 100mm × 100mm plate-like portion, with carbon fibers filling to the front end of the rib during visual observation. Measurements were performed similarly to those in Example 1. The results showed that the maximum width w of the protrusion was 1.5mm, the radius of curvature R of the surface formed by the protrusion and the plate-like portion was 0.2mm, the thickness t of the plate-like portion was 0.3mm, and w / t was 5. Furthermore, the plate-like portion was entirely formed of a unidirectional layer; therefore, in this molded body, t = t'.

[0242] The following tests were performed in the same manner as in Example 2: <Appearance Quality: Rib Inspection of Design Surface>, <Appearance Quality: Scratch Inspection of Design Surface>, <Fiber Volume Content (Vf) Measurement>, and <Resin Enrichment Inspection of Protrusion Section>. The results showed that in <Appearance Quality: Rib Inspection of Design Surface>, under uncoated conditions, the reflected light from the fluorescent lamp showed no deformation at any angle. Furthermore, in <Appearance Quality: Scratch Inspection of Design Surface>, no scratches were observed on the entire design surface at any angle. Further, in <Fiber Volume Content (Vf) Measurement>, Vf was 54%. In <Resin Enrichment Inspection of Protrusion Section>, resin enrichment was less than 3%.

[0243] [Example 15] Similar to Example 2, a unidirectional prepreg blank #P384-S-10 (carbon fiber (4,900 MPa, tensile modulus 235 GPa), FAW=100 g / m²) was prepared at Toray Industries, Inc. 2 A thermosetting epoxy resin (Rc=55%) was inserted through a notch. A prepreg blank of 100mm × 100mm was inserted through this notch, and four pieces were cut from one prepreg blank substrate. These pieces were then stacked in a configuration of [+45 / -45]² to prepare a prepreg blank substrate laminate. Using this prepreg blank substrate laminate, it was molded under the same mold and conditions as in Example 14 to obtain a fiber-reinforced plastic.

[0244] The obtained fiber-reinforced plastic has a rib in the center of a 100mm × 100mm × plate-like portion, with carbon fibers filling the front end of the rib during visual observation. Measurements were performed similarly to those in Example 1. The results showed that the maximum width w of the protrusion was 1.5mm, the radius of curvature R of the surface formed by the protrusion and the plate-like portion was 0.2mm, the thickness t of the plate-like portion was 0.3mm, and w / t was 5. Furthermore, the plate-like portion was entirely formed of a unidirectional layer; therefore, in this molded body, t = t'.

[0245] The following procedures were performed in the same manner as in Example 2: <Appearance Quality: Rib Inspection of Design Surface>, <Appearance Quality: Scratch Inspection of Design Surface>, <Fiber Volume Content (Vf) Measurement>, and <Resin Enrichment Inspection of Protrusion Section>. The results showed that in <Appearance Quality: Rib Inspection of Design Surface>, under uncoated conditions, the reflected light from the fluorescent lamp showed no deformation at any angle. Furthermore, in <Appearance Quality: Scratch Inspection of Design Surface>, no scratches were observed on the entire design surface at any angle. Further, in <Fiber Volume Content (Vf) Measurement>, Vf was 40%. In <Resin Enrichment Inspection of Protrusion Section>, resin enrichment was 5% or more.

[0246] [Example 16] Similar to Example 2, a unidirectional prepreg blank #P384-S-10 (carbon fiber (4,900 MPa, tensile modulus 235 GPa), FAW=100 g / m²) was prepared at Toray Industries, Inc. 2 A thermosetting epoxy resin (Rc=40%) was inserted through a notch. A prepreg blank was inserted through this notch, and four prepreg blanks of 100mm × 100mm size were cut out and stacked in a configuration of [+45 / -45 / 90 / +45] to prepare a prepreg blank substrate laminate. The prepreg blank substrate laminate was placed in the same mold as in Example 2, with each layer perpendicular to the fiber orientation direction relative to the ribs at a 90° angle, becoming the second layer from the upper mold side. Molding was performed under the same conditions as in Example 2 to obtain fiber-reinforced plastic.

[0247] The obtained fiber-reinforced plastic has a rib in the center of a 100mm × 100mm × plate-like portion, with carbon fibers filling the front end of the rib during visual observation. Measurements were performed similarly to those in Example 1. The results showed that the maximum width w of the protrusion was 1.5mm, the radius of curvature R of the surface formed by the protrusion and the plate-like portion was 0.2mm, the thickness t of the plate-like portion was 0.3mm, and w / t was 5. Furthermore, the plate-like portion was entirely formed of a unidirectional layer; therefore, in this molded body, t = t'.

[0248] The same procedures as in Example 2 were followed for <Appearance Quality: Rib Inspection of Design Surface> and <Resin Enrichment Inspection of Protrusion Section>. As a result, in <Appearance Quality: Rib Inspection of Design Surface>, under uncoated conditions, the reflected light from the fluorescent lamp did not deform at any angle.

[0249] Furthermore, when inspected using the methods described in "Appearance Quality: Scratch Inspection of Design Surfaces", it was found that scratches could only be partially observed at a certain constant angle, but could be concealed by painting.

[0250] Furthermore, the determination was performed using the method described in "Determination of Fiber Volume Content (Vf)", and the result was Vf = 60%.

[0251] In addition, in the <Inspection of Resin Enrichment in Protrusion Section>, the resin enrichment was 3% or more but less than 5%.

[0252] [Example 17] Using the same slits inserted as in Example 2, eleven pieces of a 100mm × 100mm prepreg substrate were cut from one prepreg substrate and stacked in a configuration of [+45 / -45]5[+45]. At the bottom, a Toray Industries fabric prepreg (#CO6343B, carbon fiber tensile strength 3,530MPa, tensile modulus 230GPa, weight per unit area 198g / m²) was placed as the design surface substrate. 2 Using the same mold as in Example 7, with the prepreg fabric blank as the lower mold side, the lower mold temperature was set to 150°C, the upper mold temperature to 140°C, the residual heat time from placing the prepreg substrate laminate in the mold to applying pressure was 10 seconds, and the pressure was 6 MPa. Otherwise, the pressure molding was performed under the same conditions as in Example 1 to obtain fiber-reinforced plastic.

[0253] The obtained fiber-reinforced plastic has a rib in the center of a 100mm × 100mm plate-like portion, with carbon fibers filling the front end of the rib in visual observation. Measurements were performed similarly to those in Example 1. The results showed that the maximum width w of the protrusion was 8.0mm, the radius of curvature R of the surface formed by the protrusion and the plate-like portion was 2.0mm, the thickness t of the plate-like portion was 1.2mm, and the w / t ratio was 7. Furthermore, compared to the non-unidirectional layer, the total thickness t' of the unidirectional layer located on the protrusion side was 1.0mm, and the w / t' ratio was 8.

[0254] The same test was performed as in Example 1, and the results showed that, under uncoated conditions, the reflected light from the fluorescent lamp did not deform at any angle.

[0255] Furthermore, the inspection was conducted using the methods described in "Appearance Quality: Scratch Inspection of Design Surfaces," and no scratches were observed on the entire design surface from any angle.

[0256] Furthermore, the determination was performed using the method described in "Determination of Fiber Volume Content (Vf)", and the result was Vf was 56%.

[0257] The inspection of "Appearance Quality: Bubble Inspection on Fabric Design Surface" revealed that two bubbles could be visually identified.

[0258] In addition, the thickness of the mesh of the fabric in the cross section of the molded article was measured, and the result was that the thickness of the mesh was 0.23 mm.

[0259] [Comparative Example 1] The prepreg blank was inserted through a notch, similar to that in Example 2. Four pieces of a 100mm × 100mm prepreg blank substrate were cut out and stacked in a configuration of [+45 / -45]2. A straight-line mold with a rib groove for forming the protrusions (ribs) having a maximum width of 9.0mm, a front end width of 1.0mm, a radius of curvature of 2.0mm, a depth of 3mm, and a length of 60mm was used. Otherwise, the prepreg blank substrate laminate was press-molded under the same conditions as in Example 1 to obtain fiber-reinforced plastic.

[0260] The obtained fiber-reinforced plastic has a rib in the center of a 100mm × 100mm plate-like portion, with carbon fibers filling the front end of the rib during visual observation. Measurements were performed similarly to those in Example 1. The results showed that the maximum width w of the protrusion was 9.0mm, the radius of curvature R of the surface formed by the protrusion and the plate-like portion was 2.0mm, the thickness t of the plate-like portion was 0.3mm, and w / t was 30. Furthermore, since the plate-like portion was entirely formed of a unidirectional layer, t = t' in this molded body.

[0261] The same inspection was performed as in Example 1. As a result, the reflected light was deformed at any angle before and after the coating, and depressions could also be observed.

[0262] Furthermore, when inspected using the methods described in "Appearance Quality: Scratch Inspection of Design Surfaces", it was found that scratches could only be partially observed at a certain constant angle, but could be concealed by painting.

[0263] Furthermore, the determination was performed using the method described in "Determination of Fiber Volume Content (Vf)", and the result was Vf = 60%.

[0264] [Comparative Example 2] The prepreg blank, with the same slits inserted as in Example 2, is used to cut two pieces from a 100mm × 100mm prepreg substrate. These pieces are then stacked in a [+45 / -45] configuration. Further, a Toray Industries fabric prepreg blank (#CO6343B, carbon fiber tensile strength 3,530MPa, tensile modulus 230GPa, area weight 198g / m²) is placed at the bottom as the design surface substrate. 2 The prepreg substrate laminate was press-molded under the same mold and conditions as Comparative Example 1, with the prepreg fabric blank as the lower mold side, to obtain fiber reinforced plastic.

[0265] The obtained fiber-reinforced plastic has a rib in the center of a 100mm × 100mm plate-like portion, with carbon fibers filling the front end of the rib in visual observation. Measurements were performed similarly to those in Example 1. The results showed that the maximum width w of the protrusion was 9.0mm, the radius of curvature R of the surface formed by the protrusion and the plate-like portion was 2.0mm, the thickness t of the plate-like portion was 0.3mm, and the w / t ratio was 30. Furthermore, compared to the non-unidirectional layer, the minimum total thickness t' of the unidirectional layer located on the protrusion side was 0.1mm, and the w / t' ratio was 90.

[0266] The same inspection was performed as in Example 1. As a result, the reflected light was deformed at any angle before and after coating, and larger depressions than those of the molded article in Comparative Example 1 could also be observed.

[0267] Furthermore, the inspection was conducted using the method described in "Appearance Quality: Scratch Inspection of Design Surfaces," and the result was that scratches were visible on the entire design surface, making it unsuitable for painting.

[0268] Furthermore, the determination was performed using the method described in "Determination of Fiber Volume Content (Vf)", and the result was Vf = 63%.

[0269] [Table 1] [Table 2] [Table 3] [Table 4] Industrial availability The fiber-reinforced plastic of the present invention is preferably used in components requiring strength, rigidity, and lightweight, as well as components with complex shapes that require shape conformity with other components. In particular, it can be used in the aforementioned high-strength components such as bicycle cranks and frames, golf club shafts and heads, structural components such as automobile doors, seats, components, modules, or frames, outer panels and interior materials, and mechanical parts such as robotic arms. Furthermore, it is also preferably used in structural components and outer panels of medical devices and information communication equipment.

[0270] Explanation of reference numerals in the attached figures 1: Maximum width of the protrusion 2: Width of the cross-section of the protrusion 3: Height of the protrusion 4: Insert the cut into the prepreg blank 5: Fiber orientation direction 6: Fiber vertical direction 7: Discontinuous incisions 8: Continuous incisions 9: Intermittent oblique cuts (at a positive angle relative to the fiber direction) 10: Discontinuous oblique cuts (at a negative angle relative to the fiber direction) 11: Columns of discontinuous incisions 20: Length direction of the protrusion 21: Width direction of the protrusion 22: Cross-section of the protrusion 23: Longitudinal section of the protrusion 100: plate-shaped part 101: Thickness of the plate-like portion (t) 102: Non-unidirectional layer 103: Total thickness of unidirectional layers (t') 104: Fabric 105: Warp or weft yarns of a fabric 106: Weft or warp yarns of a fabric 107: Thickness of the fabric mesh 108: Step difference between warp and weft yarns 109: Bubbles 200: Protrusion 201: The curved surface formed by the plate-like part and the protrusion. 202: Maximum width (w) of the protrusion 203: Height of the protrusion 300: Reinforcing Fiber 400: The surface layer opposite to the side with the protrusion. 401: Reinforcing Fiber 402: Mesh distortion 500: Depression 600: Unfilled area

Claims

1. A fiber-reinforced plastic, characterized in that it is formed of a shape having a plate-like portion and at least one protrusion arising from at least one side of the plate-like portion, wherein... In the fiber-reinforced plastic, the interior of the plate-shaped portion has at least one layer of multiple reinforcing fibers arranged unidirectionally in the matrix resin, i.e., a unidirectional layer. The thickness t of the plate-shaped portion is 0.3 mm or more and 1.8 mm or less. The ratio w / t of the maximum width w of the protrusion to the thickness t of the plate-shaped portion is 0.1 or more and 27 or less.

2. The fiber-reinforced plastic as described in claim 1, wherein, The fiber volume fraction (Vf) of the fiber-reinforced plastic is 43% to 58%.

3. The fiber-reinforced plastic as described in claim 2, wherein, The ratio of the maximum width w of the protrusion to the thickness t of the plate-like portion, w / t, is more than 2 and less than 27.

4. The fiber-reinforced plastic as described in claim 1 or 2, wherein, The plate-shaped portion has two or more unidirectional layers inside, and the fiber orientation direction of the two unidirectional layers starting from the side with the protrusion is neither parallel nor perpendicular to the length direction of the protrusion.

5. The fiber-reinforced plastic as described in claim 1 or 2, wherein, The fiber unit area weight of at least one of the unidirectional layers located inside the plate-shaped portion is 70 g / m². 2 Above 100g / m 2 the following.

6. The fiber-reinforced plastic as described in claim 1 or 2, wherein, The plate-shaped portion has multiple layers formed of reinforcing fibers and matrix resin, and the protrusion is only on one side of the plate-shaped portion. The outermost layer of the reinforcing fibers forming the opposite side of the one-sided surface is made of fabric.

7. The fiber-reinforced plastic of claim 6, wherein, The thickness of the mesh of the fabric is less than 0.25 mm.

8. The fiber-reinforced plastic as described in claim 1 or 2, wherein, The radius of curvature R of the surface formed by the protrusion and the plate-like part is less than 2 mm.

9. The fiber-reinforced plastic as described in claim 1 or 2, wherein, The maximum width w of the protrusion is less than 8 mm.

10. The fiber-reinforced plastic as claimed in claim 1 or 2, wherein, The plate-shaped portion contains two or more unidirectional layers with different fiber unit area weights.

11. The fiber-reinforced plastic of claim 10, wherein, The outermost layer on the side of the plate-shaped portion with the protrusion is the unidirectional layer, and the fiber unit area weight of the outermost unidirectional layer is less than the fiber unit area weight of at least one unidirectional layer in the plate-shaped portion other than the outermost layer on the side with the protrusion.

12. The fiber-reinforced plastic as claimed in claim 1 or 2, wherein, The plate-like portion has multiple layers formed of reinforcing fibers and matrix resin, and the protrusion is only on one side of the plate-like portion. At least one layer of the layers other than the outermost layer of the side with the protrusion is a layer in which multiple reinforcing fibers are oriented in at least two directions in the matrix resin, i.e., a non-unidirectional layer.

13. The fiber-reinforced plastic as claimed in claim 1 or 2, wherein, The plate-shaped portion has a non-unidirectional layer, and the ratio w / t' of the maximum width w of the protrusion to the total thickness t' of the unidirectional layer located on the protrusion side relative to the non-unidirectional layer is 0.1 or more and 27 or less.

14. The fiber-reinforced plastic as claimed in claim 1 or 2, wherein, At least one of the unidirectional layers located inside the plate-like portion comprises reinforcing fibers with a fiber length of 10 to 300 mm.

15. A golf club, characterized in that, The fiber-reinforced plastic comprising any one of claims 1 to 14.

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