Flat lightweight component and method for manufacturing the same

Abstract

To provide a flat lightweight member having mechanical properties of end portions, excellent adhesion between a core layer and skin layers, good appearance quality, and excellent productivity, the flat lightweight member is characterized by having: skin layers arranged on both surfaces of the flat lightweight member, an end portion reinforcing layer arranged at an end portion of the flat lightweight member so as to be in contact with both inner surfaces of the skin layers of the both surfaces, and a core layer arranged in a space surrounded by the skin layers and the end portion reinforcing layer so as to be in direct contact with inner surfaces of the skin layers, the skin layers including one or more layers containing reinforcing fibers aligned in one direction and a first base resin, the end portion reinforcing layer containing a fiber-reinforced resin sheet, and the core layer containing thermally expandable particles and a second base resin.

Description

Technical Field

[0001] This invention relates to a flat, lightweight component (fiber-reinforced resin molded article) formed of a surface skin and an internal core layer, which can be used as a propeller blade, and a method for manufacturing the same. Specifically, it relates to a flat, lightweight component formed of fiber-reinforced resin with excellent end mechanical properties, good adhesion between the core and skin layers, good appearance quality, and high productivity, and a method for manufacturing the same. Background Technology

[0002] Fiber-reinforced resins are widely used in various industries due to their lightweight, high strength, and high rigidity. In particular, molded articles utilizing prepregs are well-suited; these prepregs are intermediate materials impregnated with resin within a fiber-reinforced material formed from equal-length reinforcing fibers. Furthermore, sandwich structures with a fiber-reinforced resin outer layer and a porous core layer are effectively utilized in aircraft, automobiles, ships, and sports and leisure applications due to their lightweight and high toughness. As a type of fiber-reinforced resin molded article with such a sandwich structure, a flat, lightweight component is known, comprising an outer layer formed from a fiber-reinforced substrate and a core layer formed from lightweight particles and a matrix resin. Here, a flat, lightweight component refers to a structure whose perimeter and cross-sectional shape change along the length direction, primarily for use as a propeller blade.

[0003] As such a flat, lightweight component, a propeller blade is known to be formed by laminating and bonding a prepreg blank on the upper surface and a prepreg blank on the lower surface in the thickness direction at the end. This flat, lightweight component is obtained by laminating a prepreg blank on the upper surface in one split mold and a prepreg blank on the lower surface in another split mold, and by placing a foaming agent in the space formed by the two prepreg blanks when the mold is closed (for example, Patent Document 1).

[0004] Furthermore, as a similar flat lightweight component, there is a known flat lightweight component whose main part is composed of a skin layer, a core layer, and a separation layer, and whose peripheral part (the outer periphery of the flat lightweight component when viewed from the direction with the largest projected area) is composed of a skin layer and a core layer. When used as a propeller blade, a reinforcing fiber for reinforcement is additionally disposed at positions corresponding to the leading and trailing edges. This flat lightweight component has a separation layer disposed between the core layer and the skin layer to inhibit the passage of lightweight particles. Using this separation layer, the lightweight particles constituting the core layer are separated from the lightweight particles in the matrix resin, allowing only the matrix resin to impregnate the dry reinforcing fiber substrate constituting the skin layer, thus forming the skin layer (e.g., Patent Document 2).

[0005] Furthermore, there are known techniques for creating preforms by stacking prepreg blanks with regularly distributed cuts throughout the entire in-plane area in order to obtain uniform mechanical properties and excellent dimensional stability of flat, lightweight parts (e.g., Patent Document 3).

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Application Publication No. 2020-151876

[0009] Patent Document 2: Japanese Patent Application Publication No. 8-276441

[0010] Patent Document 3: Japanese Patent No. 5272418 Summary of the Invention

[0011] The problem that the invention aims to solve

[0012] However, as mentioned above, for a flat, lightweight component formed by laminating and bonding prepreg blanks on the upper and lower surfaces in the thickness direction at the ends, there is a required area at the ends for laminating and bonding the two prepreg blanks. Therefore, a prepreg blank with a higher specific gravity needs to be placed in an area that should be formed by a lightweight core layer, resulting in an increase in the weight of the flat, lightweight component. Furthermore, for the same reason, the shape of the flat, lightweight component with this configuration is sometimes limited. On the other hand, if a structure is formed by simply butt-jointing the ends of the prepreg blanks together, there is a problem of reduced joint strength and leakage of lightweight particles and matrix resin forming the core layer to the outside of the flat, lightweight component, thus impairing its appearance.

[0013] Furthermore, for conventional flat, lightweight components whose main part consists of a skin layer, a core layer, and a separation layer, and whose peripheral part consists of a skin layer and a core layer, and which have additional reinforcing fibers for reinforcement arranged at locations corresponding to the leading and trailing edges as described above, if the separation layer is not properly positioned, peeling may occur near the separation layer after long-term use, resulting in a problem where the core layer and skin layer cannot be firmly integrated.

[0014] Furthermore, in conventional manufacturing methods for flat, lightweight parts, where a prepreg blank is stacked on the upper surface of one split mold and on the lower surface of another split mold, and a foaming agent is placed in the space formed by the two prepreg blanks during mold closing, it is necessary to stack the prepreg blanks on the surface of a mold with a three-dimensional shape at room temperature and then heat the mold to cure the prepreg blanks. This not only requires a large amount of labor, special technology and equipment in the stacking process, but also requires a lot of time for the mold to heat up and cool down, thus causing productivity problems.

[0015] Furthermore, in conventional methods for manufacturing flat, lightweight components where a portion of the matrix resin constituting the core layer is impregnated and cured into a dry reinforcing fiber substrate via a release layer to form a skin layer, when the flat, lightweight component is not a simple flat plate but has a three-dimensional shape, the release layers, which are arranged on the top and bottom respectively, can shift during molding, making it difficult to obtain flat, lightweight components with high precision and minimal deviation. Additionally, positioning the reinforcing fibers during the placement process is difficult, and they are prone to shifting during the molding of the fiber-reinforced resin, sometimes resulting in a change in the center of gravity of the flat, lightweight component. Moreover, during the impregnation of the reinforcing fibers with the matrix resin, air bubbles, known as voids, can sometimes form at the ends, thereby reducing mechanical properties and impairing appearance.

[0016] As described above, in the aforementioned conventional techniques, it is very difficult to obtain a flat, lightweight component with excellent end mechanical properties, good adhesion between the core layer and the skin layer, and a good appearance.

[0017] Therefore, the present invention addresses the problems described above by providing a flat, lightweight component with excellent end mechanical properties, good adhesion between the core and the skin, good appearance quality, and high productivity, as well as a method for manufacturing the same.

[0018] Methods for solving problems

[0019] To address the aforementioned issues, the present invention employs any of the following configurations.

[0020] (1) A flat lightweight component, characterized in that it comprises: a skin layer disposed on two surfaces of the aforementioned flat lightweight component, an end reinforcement layer disposed at the end of the aforementioned flat lightweight component in such a manner as to contact the two inner surfaces of the skin layer on the two surfaces, and a core layer disposed in a space surrounded by the aforementioned skin layer and the aforementioned end reinforcement layer in such a manner as to directly contact the inner surface of the aforementioned skin layer, the aforementioned skin layer comprising one or more layers comprising reinforcing fibers unidirectionally filamentous and a first matrix resin, the aforementioned end reinforcement layer comprising fiber-reinforced resin sheet, and the aforementioned core layer comprising thermally expandable particles and a second matrix resin.

[0021] (2) The flat lightweight component as described in (1) above, characterized in that the aforementioned fiber-reinforced resin sheet consists of reinforcing fibers and a first matrix resin filaments unidirectionally filamented.

[0022] (3) The flat lightweight component as described in (1) above, characterized in that the aforementioned fiber-reinforced resin sheet is a fiber-reinforced foam containing reinforcing fibers.

[0023] (4) The flat lightweight component described in any of (1) to (3) above is characterized in that the reinforcing fibers that are raised from the aforementioned skin layer penetrate the aforementioned core layer.

[0024] (5) The flat lightweight component described in any of (1) to (4) above is characterized in that the reinforcing fibers that are raised from the aforementioned end reinforcing layer penetrate the aforementioned core layer.

[0025] (6) The flat lightweight component described in any of (1) to (5) above is characterized in that the space surrounded by the aforementioned skin layer and the aforementioned end reinforcement layer is a closed space.

[0026] (7) The flat lightweight component described in any one of (1) to (6) above is characterized in that the fiber-reinforced resin sheet in the aforementioned end reinforcement layer has a roll structure or a folded structure.

[0027] (8) A method for manufacturing a flat, lightweight component, wherein the method uses a double-sided mold including an upper mold and a lower mold, the aforementioned manufacturing method being characterized by having:

[0028] The preparation process includes preparing a skin layer of one and a skin layer of the other using a prepreg blank containing reinforcing fibers unidirectionally filamented and a first matrix resin, and preparing an end reinforcement layer using fiber-reinforced resin sheets.

[0029] The first configuration step involves placing the aforementioned skin layer in the aforementioned lower mold that has been heated to the molding temperature, and placing the aforementioned end reinforcement layer on at least a portion of the peripheral portion of the aforementioned skin layer.

[0030] In the input process, a mixture of thermally expandable particles and a second matrix resin is placed on the skin of the aforementioned.

[0031] In the second configuration step, the skin layer of the other entity is further configured on the upper surface of the skin layer of the other entity, such that the end reinforcement layer contacts at least a portion of the peripheral edge of the skin layer of the other entity; and

[0032] The mold closing process involves closing the aforementioned upper mold, which has been heated to the molding temperature.

[0033] The aforementioned manufacturing method also includes a step of causing the aforementioned thermally expandable particles to expand in volume to become a core layer.

[0034] (9) A method for manufacturing a flat, lightweight component, wherein the method uses a double-sided mold including an upper mold and a lower mold, the aforementioned manufacturing method being characterized by having:

[0035] The preparation process includes bonding an end reinforcement layer comprising a fiber-reinforced resin sheet to at least a portion of the periphery of a skin layer comprising a prepreg blank, preparing a skin layer with an end reinforcement layer, and preparing a skin layer comprising the other prepreg blank, wherein the prepreg blank comprises reinforcing fibers unidirectionally filamented and a first matrix resin.

[0036] The first configuration step involves configuring the aforementioned skin layer with end reinforcement layer onto the aforementioned lower mold that has been heated to the molding temperature;

[0037] In the input process, a mixture of thermally expandable particles and a second matrix resin is placed on the skin of the aforementioned.

[0038] In the second configuration step, the skin layer of the other entity is further configured on the upper surface of the skin layer with the end reinforcement layer, such that the end reinforcement layer contacts at least a portion of the periphery of the skin layer of the other entity; and

[0039] The mold closing process involves closing the aforementioned upper mold, which has been heated to the molding temperature.

[0040] The aforementioned manufacturing method also includes a step of causing the aforementioned thermally expandable particles to expand in volume to become a core layer.

[0041] (10) The method for manufacturing a flat, lightweight component as described in (8) or (9) above, characterized in that the aforementioned reinforcing fiber resin sheet is a prepreg blank comprising reinforcing fibers unidirectionally filamented and a first matrix resin.

[0042] (11) The method for manufacturing a flat, lightweight component as described in (8) or (9) above, characterized in that the aforementioned reinforcing fiber resin sheet is a fiber-reinforced foam containing reinforcing fibers.

[0043] (12) The method for manufacturing a flat, lightweight component as described in any of (8) to (11) above, characterized in that a prepreg blank with a cut is used as the aforementioned prepreg blank.

[0044] (13) The method for manufacturing a flat lightweight component as described in any of (8) to (12) above is characterized in that, up to the completion of the aforementioned mold closing process, at least one of the skin layers corresponding to the inner surface of the flat lightweight component is fuzzed.

[0045] (14) The method for manufacturing a flat lightweight component as described in any of (8) to (13) above is characterized in that, up to the completion of the aforementioned mold closing process, the portion of the aforementioned end reinforcement layer corresponding to the inner surface of the flat lightweight component is roughened.

[0046] Invention Effects

[0047] According to the flat lightweight component and its manufacturing method disclosed in this invention, a flat lightweight component with excellent end mechanical properties, good adhesion between the core layer and the skin layer, good appearance quality, and excellent productivity can be obtained. Attached Figure Description

[0048] [Figure 1 [A] is a top view (a) and a cross-sectional view (b) along A-A' of an example of a flat, lightweight component of the present invention.

[0049] [ Figure 2 [A] is a cross-sectional view (a) showing an example of a napped skin layer in an example of a flat, lightweight component of the present invention, and an enlarged view of the example of a napped skin layer.

[0050] [ Figure 3 [This is a cross-sectional view showing an example of the positional relationship between the skin, end reinforcement layer, and core layer of the flat, lightweight component of the present invention.]

[0051] [ Figure 4 [This is a perspective top view showing an example of a flat, lightweight component of the present invention, with an enclosed space surrounded by a skin layer and an end reinforcement layer.]

[0052] [ Figure 5 [This is an example of an end reinforcement layer having a roll-like or folded structure in a flat, lightweight component of the present invention.]

[0053] [ Figure 6 [Illustration 1] is a diagram illustrating the various steps of a method for manufacturing a flat, lightweight component according to the present invention.

[0054] [ Figure 7 [Illustration 1] is a diagram illustrating the various steps of another manufacturing method for the flat, lightweight component of the present invention. Detailed Implementation

[0055] Hereinafter, the present invention will be described in detail with reference to the accompanying drawings and embodiments.

[0056] The flat, lightweight component of the present invention comprises: a skin layer disposed on two surfaces; an end reinforcement layer disposed at the ends of the aforementioned flat, lightweight component in contact with the two inner surfaces of the skin layer on the two surfaces; and a core layer disposed in a space surrounded by the aforementioned skin layer and the aforementioned end reinforcement layer in direct contact with the inner surface of the aforementioned skin layer. The aforementioned skin layer is formed using one or more layers of prepreg containing reinforcing fibers unidirectionally filamented and a first matrix resin, comprising one or more layers containing reinforcing fibers and a first matrix resin. Furthermore, the aforementioned end reinforcement layer comprises a fiber-reinforced resin sheet, and the aforementioned core layer comprises thermally expandable particles as lightweight particles and a second matrix resin.

[0057] Figure 1 An embodiment of the flat, lightweight component of the present invention used as a propeller blade is shown. Figure 1 (a) in the figure represents a top view of the flat, lightweight component 1, with the front end a on the right and the root b on the left. The A-A' section of this flat, lightweight component 1 (i.e., the section of the flat, lightweight component 1 perpendicular to its length direction) is shown in the figure. Figure 1(b) of the diagram. The flat, lightweight component 1 mainly comprises skin layers 21 and 22, a core layer 30, and end reinforcement layers 40 and 41. Skin layers 21 and 22 are disposed on the two surfaces of the flat, lightweight component 1. The end reinforcement layers 40 and 41 are disposed at the ends (at locations corresponding to the leading and trailing edges of the propeller blades) in a manner that contacts the two inner surfaces of the skin layers 21 and 22 on the two surfaces. The core layer 30 is disposed in direct contact with the skin layers in the space surrounded by the skin layers 21 and 22 and the end reinforcement layers 40 and 41.

[0058] [Cortex]

[0059] The skin layer in this invention is mainly formed using a prepreg containing reinforcing fibers unidirectionally filamentous and a first matrix resin, and includes one or more layers containing reinforcing fibers and a first matrix resin.

[0060] Here, the inner surface of the skin refers to the surface located on the inner surface side of the flat, lightweight component within the skin. It should be noted that, unless otherwise specified, "surface" refers to the outer surface of the flat, lightweight component.

[0061] In this invention, the thickest portion of the skin layer on one side of the surface constituting the flat, lightweight component is preferably formed from two or more layers of prepreg preform, more preferably from four or more layers of prepreg preform. That is, this portion preferably has two or more layers comprising reinforcing fibers and a first matrix resin, more preferably four or more layers.

[0062] The thickness of the skin layer in this invention is preferably 0.1 mm to 10 mm, more preferably 0.2 mm to 5 mm, and even more preferably 0.4 mm to 2 mm. By keeping the thickness within the above-mentioned preferred range, heat can be easily and evenly transferred to the interior of the laminate during molding, thereby obtaining a flat and lightweight component with excellent appearance.

[0063] The skin layer is preferably formed using a prepreg blank having two or more orientation directions, more preferably using a prepreg blank having three or more orientation directions. Thus, the skin layer becomes a skin layer having two or more orientation directions, more preferably a skin layer having three or more orientation directions. Such a prepreg blank is obtained by preparing multiple prepreg blanks with reinforcing fibers unidirectionally filamented and stacking them in a manner that staggers the orientation directions of the reinforcing fibers. When the length direction of the flat, lightweight component is set to the 0-degree direction, for example, as preferred stacking configurations, examples include stacking configurations containing 0 degrees and 90 degrees, stacking configurations containing 0 degrees and ±45 degrees, stacking configurations containing 0 degrees and ±30 degrees, and stacking configurations containing 0 degrees, ±45 degrees, and 90 degrees as preferred methods.

[0064] Furthermore, the skin layer uses a prepreg preform with one or more layers of reinforcing fibers unidirectionally twisted together, i.e., a unidirectional prepreg preform. Moreover, from the viewpoint of balancing impact characteristics and rigidity, it is preferable to use a prepreg preform with one or more layers of continuous fibers woven together, i.e., a fabric prepreg preform. In particular, a preferred method is to arrange the fabric prepreg preform on the outermost surface of the flat lightweight component and arrange the unidirectional prepreg preform on its inner side with the fiber direction aligned with the length direction of the flat lightweight component. This results in a flat lightweight component having a fabric substrate with reinforcing fibers on the outermost surface and a skin layer with reinforcing fibers arranged unidirectionally on the inner side. With this configuration, when used as a propeller blade, the fabric substrate derived from the fabric prepreg preform can suppress breakage of the flat lightweight component caused by impacts from projectiles, while the reinforcing fibers derived from the unidirectional prepreg preform can withstand tensile stress applied in the length direction of the flat lightweight component.

[0065] [End Reinforcement Layer]

[0066] In this invention, the end reinforcement layer is disposed at the periphery of the flat, lightweight component. The periphery of the flat, lightweight component, as referred to in this invention, means the surrounding portion when the flat, lightweight component is projected from above (i.e., the outer periphery of the flat, lightweight component when viewed from the direction with the largest projected area). Furthermore, the inner surface of the end reinforcement layer refers to the surface of the end reinforcement layer located on the inner surface side of the flat, lightweight component.

[0067] The end reinforcement layer in this invention comprises fiber-reinforced resin sheets.

[0068] The fiber-reinforced resin sheet is preferably composed of a prepreg comprising reinforcing fibers unidirectionally filamented and a first matrix resin. Furthermore, the fiber-reinforced resin sheet is preferably composed of two or more prepreg layers, more preferably four or more prepreg layers. With such a fiber-reinforced resin sheet, the end reinforcement layer becomes an end reinforcement layer comprising one or more layers comprising reinforcing fibers unidirectionally filamented and a first matrix resin.

[0069] On the other hand, the fiber-reinforced resin sheet of the end reinforcement layer is preferably a fiber-reinforced foam (porous body) containing reinforcing fibers. Examples of such fiber-reinforced foams include sandwich structures (e.g., described in International Publication No. 14 / 162873) and nonwoven fabrics with thermoplastic resin impregnated on one side and reinforcing fibers exposed on the other side (e.g., described in Japanese Patent Application Publication No. 2014-172201).

[0070] While it also depends on the size of the flat, lightweight component, the cross-sectional area of ​​the end reinforcement layer of the present invention is preferably 1 mm² in a section orthogonal to the contour direction of the peripheral portion. 2 Above 1200mm2 The following is more preferably 5mm 2 Above 500mm 2 The following is an example. By having a thickness with this cross-sectional area, heat can be easily and uniformly transferred to the interior of the laminate (i.e., throughout the entire thickness of the end reinforcement layer), thereby obtaining a flat and lightweight component with excellent appearance.

[0071] The end reinforcement layer of the present invention preferably has a fiber orientation along the contour of the peripheral portion. For example, after making an elongated laminate with reinforcing fibers oriented in the length direction using fiber-reinforced resin sheets, the laminate can be configured along the contour of the peripheral portion of the desired flat lightweight component to have a fiber orientation along the contour of the peripheral portion of the flat lightweight component.

[0072] [Core Layer]

[0073] Unlike conventional flat, lightweight components with a separation layer between the core and the skin layer, the core layer in this invention is in direct contact with the skin layer. This configuration allows for a strong integration of the core and skin layers, preventing peeling near the separation layer even with prolonged use.

[0074] The core layer of this invention is formed of a lightweight resin and a second matrix resin. Regarding the weight ratio of lightweight particles (thermally expandable particles) to the second matrix in the core layer, when the weight of the second matrix resin is set to 100%, it is preferable to set the lightweight particles to a range of 5% to 100%, more preferably to a range of 10% to 40%. By setting the weight of the lightweight particles to 5% or more, the specific gravity of the core layer is reduced, making it easier to achieve lightweight properties. Furthermore, by setting it to 10% or more, localized "resin enrichment" caused by the separation of the second matrix resin from the lightweight particles can be reduced, thus the core layer has a more homogeneous structure and can reduce the deviation of the center of gravity. On the other hand, by setting it to 100% or less, the second matrix resin exists between the lightweight particles, causing the lightweight particles to cross-link with each other, making the core layer rigid and able to maintain its shape. It should be noted that when the ratio is greater than 100%, the cross-linking of the lightweight particles becomes insufficient, resulting in a brittle core layer that is easily deformed. Furthermore, by using a content of less than 40%, the second matrix resin can cover the area around the lightweight particles, thus suppressing the generation of cracks in the core layer and enabling the core layer to maintain its mechanical properties well over a long period of time.

[0075] [Fiber-reinforced resin sheets]

[0076] The fiber-reinforced resin sheet used in this invention mainly comprises reinforcing fibers and a first matrix resin.

[0077] The reinforcing fibers in fiber-reinforced resin sheets can be continuous or discontinuous. The shape of the fiber-reinforced resin sheet is not particularly limited, but from a mechanical property point of view, it is preferable to use a prepreg preform as the fiber-reinforced resin sheet. Furthermore, from a lightweight point of view, it is preferable to use fiber-reinforced resin foam as the fiber-reinforced resin sheet.

[0078] [Prepreg blank]

[0079] The prepreg used in this invention is mainly composed of reinforcing fibers and a first matrix resin.

[0080] The volume content of the reinforcing fiber preferred for the prepreg blank is preferably 40% to 80%, more preferably 45% to 75%, and even more preferably 50% to 70%.

[0081] Regarding the amount of reinforcing fibers contained in the prepreg, the area weight of the reinforcing fibers when formed into sheets is preferably 50 g / m². 2 Above 1000g / m 2 The following applies. If the weight per unit area is too low, voids without reinforcing fibers may sometimes form within the surface of the prepreg blank. By setting the weight per unit area to the lower limit of the aforementioned preferred range or higher, voids that could become the starting point of damage can be eliminated. Furthermore, as long as the weight per unit area is below the upper limit of the aforementioned preferred range, heat can be uniformly transferred to the interior during preheating during molding. Considering both the uniformity of the structure and the uniformity of heat transfer, a weight per unit area of ​​100 g / m² is more preferable. 2 Above 600g / m 2 The following is a further preferred value: 150g / m 2 Above 400g / m 2 the following.

[0082] The weight per unit area of ​​the reinforcing fiber was determined by the following method: a 10 cm square area was cut from the sheet of reinforcing fiber, its mass was measured, and then divided by the area. The measurement was performed 10 times at different locations on the sheet of reinforcing fiber, and the average value was used as the weight per unit area of ​​the reinforcing fiber.

[0083] [Reinforcing Fibers]

[0084] In this invention, the reinforcing fibers used in fiber-reinforced resin sheets, prepreg blanks, and fiber-reinforced foams include, for example, organic fibers such as aramid fibers, polyethylene fibers, and poly(p-phenylenebenzodioxazole) fibers (PBO), inorganic fibers such as glass fibers, carbon fibers, silicon carbide fibers, alumina fibers, Tyranno fibers, basalt fibers, and ceramic fibers, metal fibers such as stainless steel fibers and steel fibers, as well as boron fibers, natural fibers, and modified natural fibers. Among these, carbon fibers are particularly lightweight and possess exceptionally superior properties in terms of specific strength and specific modulus of elasticity, as well as excellent heat resistance and chemical resistance, making them suitable for components such as automotive panels and aircraft propulsion blades where lightweighting is desired. PAN-based carbon fibers, which are readily available for high-strength applications, are preferred.

[0085] [Matrix resin]

[0086] In the flat, lightweight component of the present invention, the first matrix resin and the second matrix resin are in a cured state.

[0087] Examples of thermosetting resins used as the first matrix resin in the prepreg blank of this invention include epoxy resin, unsaturated polyester resin, vinyl ester resin, phenolic resin, epoxy acrylate resin, urethane acrylate resin, phenoxy resin, alkyd resin, urethane resin, maleimide resin, cyanate ester resin, etc.; and thermoplastic resins such as polyamide resin, polyacetal resin, polyacrylate resin, polysulfone resin, acrylonitrile-butadiene-styrene copolymer (ABS) resin, polyester resin, acrylic resin, polybutylene terephthalate (PBT) resin, polyethylene terephthalate (PET) resin, polyethylene resin, polypropylene resin, polyphenylene sulfide (PPS) resin, polyetheretherketone (PEEK) resin, liquid crystal polymer, vinyl chloride resin, polytetrafluoroethylene and other fluorinated resins, and silicone resin. Thermosetting resins are particularly preferred among these. By making the first matrix resin a thermosetting resin, the prepreg blank is viscous at room temperature, so that even when multiple prepreg blanks are used to form a skin, these layers are integrated by bonding, and can be molded while maintaining the desired laminate configuration.

[0088] Examples of thermosetting resins used as the second matrix resin in the core layer of this invention include epoxy resin, unsaturated polyester resin, vinyl ester resin, phenolic resin, epoxy acrylate resin, urethane acrylate resin, phenoxy resin, alkyd resin, urethane resin, maleimide resin, and cyanate ester resin; and thermoplastic resins such as polyamide resin, polyacetal resin, polyacrylate resin, polysulfone resin, acrylonitrile-butadiene-styrene copolymer (ABS) resin, polyester resin, acrylic resin, polybutylene terephthalate (PBT) resin, polyethylene terephthalate (PET) resin, polyethylene resin, polypropylene resin, polyphenylene sulfide (PPS) resin, polyetheretherketone (PEEK) resin, liquid crystal polymer, vinyl chloride resin, polytetrafluoroethylene (PTFE) and other fluorinated resins, and silicone resin. Thermosetting resins are particularly preferred. By making the second matrix resin a thermosetting resin, the cured matrix resin covers the lightweight particles of the core layer, forming a porous structure. Therefore, when the flat, lightweight part is heated, the deformation and expansion of the core layer can be prevented.

[0089] In the first matrix resin and the second matrix resin of the present invention, it is preferable that the glass transition temperature of the first matrix resin is higher than that of the second matrix resin.

[0090] [Lightweight Particles]

[0091] The lightweight particles involved in the flat lightweight component of the present invention refer to thermally expandable resin particles that expand in volume by heating during molding, as well as thermally expandable particles that are already in a state of thermal expansion but can be compressed by applying pressure.

[0092] If thermally expandable particles are mixed with the second matrix resin and heated, volume expansion occurs. If the second matrix resin is a thermosetting resin, a lightweight porous core layer is formed by curing the thermosetting resin. Alternatively, if the second matrix resin is a thermoplastic resin, a lightweight porous core layer is formed by curing the molten thermoplastic resin during cooling or by bonding the softened thermoplastic resin.

[0093] Let the volume of the mixture before expansion be V1 (cm). 3 Let the expanded volume be V2 (cm). 3 When ), the volume expansion rate α (%) of the mixture of thermally expandable particles and the second matrix resin is expressed by the following formula (1).

[0094] α=100×(V2-V1)÷V1…(1)

[0095] In the core layer, although the volume expansion rate α varies depending on the weight ratio of thermally expandable particles to the second matrix resin and the heating conditions during molding, it is preferably in the range of 30% to 2000%.

[0096] Examples of thermally expandable particles include polyacrylonitrile copolymers, polymethacrylonitrile copolymers, polyvinylidene chloride copolymers, polystyrene or polystyrene copolymers, polyolefins, and polyphenylene ether copolymers. Capsule-shaped particles containing a thermally expandable gas are preferred. In particular, thermally expandable particles using low-boiling-point hydrocarbons as the thermally expandable gas are preferred due to their large volume expansion rate and the ability to form a lightweight core layer.

[0097] The size of the thermally expandable particles is preferably in the range of 1 μm to 1 mm in average particle size before volume expansion. By making the average particle size 1 μm or more, leakage of thermally expandable particles to the surface of the flat, lightweight part caused by resin flow during molding can be suppressed. In addition, by making it 1 mm or less, the thermally expandable particles can penetrate into the thin-walled portion of the core layer, thus not only making the core layer lightweight, but also reducing the density unevenness between the thermally expandable particles in the core layer and the second matrix resin.

[0098] Examples of such thermally expandable particles include "Matsumoto Microsphere" (registered trademark) manufactured by Matsumoto Yushi Pharmaceutical Co., Ltd., "Expancel" (registered trademark) manufactured by NOBEL Co., Ltd., and "Eslen Beads" manufactured by Sekisui Chemical Co., Ltd., but the present invention is not limited to these products.

[0099] In this invention, as lightweight particles, only one type of thermally expandable particle can be used, or multiple types of thermally expandable particles can be mixed. Furthermore, the thermally expandable particles can be used alone, or for example, mixed with particles that do not undergo thermal expansion, such as glass beads.

[0100] [Further preferred embodiment of the invention]

[0101] In the flat, lightweight component of the present invention, it is preferably formed by reinforcing fibers that are raised from the skin layer and penetrate into the core layer.

[0102] Figure 2 This is one embodiment of the flat, lightweight component of the present invention. Figure 2 (a) is a cross-sectional view showing an example of the napped skin of the flat, lightweight component 1. Figure 2 (b) is an enlarged view showing an example of the napped skin of the flat, lightweight component 1. Figure 2 (b) shows the skin layer 22 and the napped reinforcing fibers 200, the core layer 30, and the fiber reinforcement portion 300 of the core layer that is partially reinforced by the napped reinforcing fibers.

[0103] Here, the state of fiber fuzzing refers to the state in which one or more reinforcing fibers fly outward from the surface (the surface with the largest surface area) of the fiber-reinforced resin sheet, prepreg blank, or fiber-reinforced foam. The lower limit of the length of the flying-out reinforcing fiber is preferably 0.1 mm or more, more preferably 0.5 mm or more, and even more preferably 1 mm or more. If the length is below the lower limit, reinforcing fibers penetrating the core layer may detach. Furthermore, the upper limit of the length of the flying-out reinforcing fiber is preferably 100 mm or less, more preferably 50 mm or less, and even more preferably 10 mm or less. If the length is above the upper limit, the reinforcing fiber may break during fuzzing. Here, the length of the fuzzed reinforcing fiber is calculated as follows: Figure 2 After embedding and grinding the region containing the boundary between the cortex and the core, as shown in (b), the length of the reinforcing fibers penetrating the core is determined by cross-sectional observation. Preferably, the napped reinforcing fibers are continuously connected from the cortex to the core, thus ensuring a strong bond between the cortex and the core.

[0104] Furthermore, in the flat, lightweight component of the present invention, it is preferable that the reinforcing fibers, which are raised from the end reinforcing layer, penetrate into the core layer.

[0105] The napped reinforcing fibers are preferably connected continuously from the end reinforcing layer to the core layer. This configuration enables a strong bond between the end reinforcing layer and the core layer.

[0106] Methods for enhancing fiber napping, as described in this article, will be discussed later.

[0107] In the flat, lightweight component of this invention, the space surrounded by the skin layer and the end reinforcement layer is preferably an enclosed space. That is, the core layer is preferably surrounded by the skin layer and the end reinforcement layer.

[0108] Figure 3 This shows a cross-section of the flat, lightweight component of the present invention (with...). Figure 1 Examples of sections (within the same direction as section A-A') are shown in the figure. Figure 3 In (a), the skin layers 21 and 22 completely reach both ends c and d of the flat, lightweight component, and the entire surface of the flat, lightweight component is covered by the skin layers 21 and 22. Additionally, Figure 3 In (b), the end reinforcement layers 40 and 41 are exposed on the surface of the flat, lightweight component. Furthermore, Figure 3 In (c), one end c of the flat, lightweight component is covered by the skin layer 23, while at the other end d, the end reinforcement layer 41 is exposed on the surface of the flat, lightweight component. Furthermore, Figure 3In (d), the skin layers 21 and 22 completely reach both ends of the flat, lightweight component, and the skin layers 21 and 22 are joined together between the two ends of the flat, lightweight component (between the aforementioned end c on one side and the aforementioned end d on the other side) to form an internal reinforcing layer 25. This internal reinforcing layer 25 can be formed not only by partially increasing the thickness of the skin layers, but also by methods such as arranging a prepreg laminate different from the skin layers between the skin layers 21 and 22, arranging reinforcing fibers with the same structure as the end reinforcing layers between the skin layers 21 and 22, or arranging a component with reinforcing fibers such as prepregs arranged around the core to form an internal reinforcing layer between the skin layers 21 and 22. A cross-section with such an internal reinforcing layer can withstand a large amount of shear load applied to the cross-section, thus it is a suitable method with excellent mechanical properties. Here, Figure 3 In (a) through (d), it can be seen that the entire surface of the flat, lightweight component is covered by skin layers 21 and 22 and end reinforcement layers 40 and 41, and the area surrounded by skin layers 21 and 22 and end reinforcement layers 40 and 41 is closed. Furthermore, through the skin layers and end reinforcement layers, in... Figure 3 A closed region is formed in (a) to (c) of the above. Figure 3 Two closed regions are formed in (d) of the middle.

[0109] Figure 4 This is an example of a perspective top view of the flat, lightweight component of the present invention, illustrating the enclosed space 50 in which the core layer of the present invention is disposed and its outline 500. The enclosed space 50 exists inside the surface of the flat, lightweight component 1, from... Figure 4 The front end a faces the root b, from Figure 3 The closed area is as described. Furthermore, at the front end a and the root b, the closed space 50 is closed by a skin layer and an end reinforcement layer, or by a laminate of a prepreg blank different from the skin layer and a skin layer. Therefore, the core layer of the present invention disposed in the closed space 50 is not exposed on the surface of the flat lightweight component 1.

[0110] Figure 4 Example (a) illustrates the case where the flat, lightweight component of the present invention has a closed space. Figure 4 Example (b) illustrates the case where the flat, lightweight component of the present invention has two parallel enclosed spaces from the front end a toward the root b. Figure 4 Example (c) illustrates a case where the flat, lightweight component of the present invention has three discontinuous enclosed spaces from the front end a toward the root b. Figure 4In (b) and (c), the internal reinforcing layer formed by the integration of multiple enclosed spaces with skin layers can be formed not only by partially increasing the thickness of the skin layers, but also by methods such as arranging a prepreg laminate different from the skin layers between the skin layers 21 and 22, arranging reinforcing fibers with the same structure as the end reinforcing layers between the skin layers 21 and 22, and arranging a component with the shape of an internal reinforcing layer formed by arranging reinforcing fibers such as prepregs around the core between the skin layers 21 and 22.

[0111] In the flat, lightweight component of this invention, an end reinforcement layer is preferably disposed throughout the entire periphery. This configuration improves the mechanical properties at the ends of the flat, lightweight component and suppresses leakage of lightweight particles forming the core layer and the second substrate to the surface of the flat, lightweight component.

[0112] In the flat, lightweight component of this invention, as described above, it is preferable that the reinforcing fibers, which originate from the skin layer and the end reinforcement layer, are incorporated into the core layer. To achieve this configuration, it is preferable to use a prepreg blank with cut edges as at least a portion of the prepreg blank used to form the skin layer and the end reinforcement layer. This is particularly suitable when the flat, lightweight component has varying thicknesses and a complex three-dimensional shape.

[0113] A prepreg blank with cuts is a prepreg blank having cuts regularly distributed throughout its entire surface area, wherein the continuous reinforcing fibers constituting the prepreg blank are cut at the locations where the cuts are present. Such regularly distributed cuts can be provided, for example, by the method described in the aforementioned Patent Document 3.

[0114] Cut-out prepregs can be used in conjunction with uncut conventional prepregs, which only make the reinforcing fibers continuous, for skin layers and end reinforcement layers.

[0115] By notching the prepreg, openings and offsets are easily created at the notch insertion point, improving the prepreg's stretchability towards the reinforcing fibers. Furthermore, the flow during compression molding opens the notch insertion point, allowing the reinforcing fiber bundles to separate, thus exhibiting flexibility and improved flowability as the prepreg. Therefore, by making the prepreg a flowable structure, the reinforcing fibers reach the ends, reducing areas of excessive resin and resulting in flat, lightweight parts with excellent mechanical properties and appearance. It should be noted that, from a flowability perspective, it is preferable to introduce notches throughout the entire thickness direction of the prepreg.

[0116] Using a prepreg blank with notches for the skin layer facilitates the formation of fuzz on the reinforcing fibers and allows them to penetrate the core layer to form a strong bond, which is therefore preferred. Furthermore, the ends of the fuzzed reinforcing fibers can penetrate deep into the core layer, thus enhancing the adhesion between the core layer and the skin layer.

[0117] Alternatively, an integral laminate of uncut prepreg and cut prepreg can be used as the skin layer. In this case, it is preferable to place the cut prepreg on the contact surface with the core layer. This method allows the uncut prepreg to exhibit excellent mechanical properties and enables the core layer and skin layer to be firmly bonded together by the cut prepreg.

[0118] When using a notched prepreg blank in the end reinforcement layer, as the core layer expands and the end reinforcement layer is pressed against the end profile of the flat, lightweight component, the tension in the fiber direction can be suppressed. Therefore, "resin enrichment" and the formation of voids are suppressed, easily improving the appearance grade and mechanical properties of the end, making it preferable. The fiber direction of the reinforcing fibers in the end reinforcement layer is preferably along the direction of the end profile of the flat, lightweight component.

[0119] For the flat, lightweight components of the present invention, it is preferable that the fiber-reinforced resin sheet in the end reinforcement layer has a rolled or folded structure.

[0120] Figure 5 (a) shows an example of a roll-like structure. Figure 5 Example (b) shows an example of a folded structure. The end reinforcement layer with a roll structure allows for easy adjustment of thickness and cross-sectional area by adjusting the amount of fiber-reinforced resin sheet, such as a prepreg, being rolled up. It is also easy to manufacture, making it particularly suitable for use when the ends of flat, lightweight components have rounded corners. On the other hand, the end reinforcement layer with a folded structure allows for thickness variation by adjusting the width and number of folds of the fiber-reinforced resin sheet, such as the prepreg, making it easier to adjust to a thinner thickness than the roll structure. Therefore, it is particularly suitable for use when the ends of flat, lightweight components have sharp shapes. That is, Figure 3 In (a) to (d), the end reinforcement layer 40 preferably has a rolled structure, and the end reinforcement layer 41 preferably has a folded structure.

[0121] [Manufacturing Method]

[0122] The present invention relates to a method for manufacturing flat, lightweight components using a double-sided mold including an upper mold and a lower mold. The method is characterized by comprising: a preparation step, wherein a skin layer of one component and a skin layer of another component are prepared using a prepreg blank comprising reinforcing fibers unidirectionally filamented and a first matrix resin, and an end reinforcement layer is prepared using fiber-reinforced resin sheets; and a first placement step, wherein the aforementioned skin layer of one component is placed in the aforementioned lower mold heated to the molding temperature, and the aforementioned end reinforcement layer is placed on at least a portion of the peripheral portion of the aforementioned skin layer of one component. The manufacturing method includes the following steps: a first step of loading the lightweight particles (thermally expandable particles) and a second matrix resin onto the inner surface of the skin of the first component (the inner surface of the skin of the final flat lightweight component); a second step of placement, in which the skin of the other component is further placed on the upper surface of the skin of the first component, such that the end reinforcement layer contacts at least a portion of the periphery of the skin of the other component; and a mold closing step, in which the upper mold, heated to the molding temperature, is closed, and the manufacturing method further includes a step of causing the lightweight particles to expand in volume to become a core layer.

[0123] Figure 6 The following describes the steps of a method for manufacturing a flat, lightweight component according to the present invention: a double-sided mold in which a cavity is formed on the mating surfaces of an upper mold and a lower mold to form the flat, lightweight component.

[0124] Figure 6 (a) is the preparation process, which is the process of preparing the skin layer 22 of one and the skin layer 21 and the end reinforcement layers 40 and 41 of the other.

[0125] For example, the skin layers 21 and 22 can be manufactured by laminating the prepreg blanks as needed after cutting them into prepreg blank cut bodies with the desired shape and desired fiber orientation. Alternatively, for example, they can be manufactured by laminating the prepreg blanks in the desired fiber orientation and then cutting them into the desired shape.

[0126] End reinforcement layers can be manufactured, for example, by laminating fiber-reinforced resin sheets to a specified thickness and then cutting them into elongated, specified widths, or by drawing or extruding them into elongated, rope-like components.

[0127] When the end reinforcement layer has a roll structure, it can be obtained, for example, by sequentially winding a single fiber-reinforced resin sheet from the end. Alternatively, it can be manufactured by folding a single fiber-reinforced resin sheet and then winding it. Furthermore, a roll structure can also be obtained from a material formed by stacking multiple fiber-reinforced resin sheets using the same steps.

[0128] When the end reinforcement layer has a folded structure, it can be manufactured, for example, by folding a single fiber-reinforced resin sheet in half, third-folding it, and then further folding it. Alternatively, it can be manufactured by folding a thin roll structure with a flat cross-sectional shape made from a single fiber-reinforced resin sheet. Furthermore, a folded structure can also be obtained from a material formed by stacking multiple fiber-reinforced resin sheets using the same steps.

[0129] When using prepreg preforms as fiber-reinforced sheets, they can be manufactured by stacking elongated, sheet-like prepreg preforms or strip-like prepreg slit tapes. Alternatively, when using fiber-reinforced foam as fiber-reinforced sheets, they can be manufactured by cutting elongated, sheet-like fiber-reinforced foam.

[0130] Next, Figure 6 (b) shows the first configuration step. In this step, the skin layer 22 of one of the components is placed in a lower mold 82 that has been heated to the molding temperature, and end reinforcement layers 40, 41 are placed on at least a portion of the periphery of the skin layer 22 of one of the components. The molding temperature set as the temperature of the lower mold also depends on the types of the first matrix resin and the second matrix resin, and in the case of using thermosetting resin, a temperature range of 80°C to 230°C is preferred. By setting the temperature to 80°C or higher, the reaction of the matrix resin can be promoted, and by setting the temperature to 230°C or lower, the decomposition of the matrix resin can be suppressed. In addition, according to the manufacturing method of the present invention, since it is not necessary to heat or cool the mold, the manufacturing time can be shortened compared with conventional methods that heat or cool the mold.

[0131] In the first configuration step, the skin layer of one component can be directly configured onto the lower mold in a planar state, or it can be configured onto the lower mold after being pre-shaped into a three-dimensional shape. Alternatively, a straight end reinforcement layer can be configured while bending along the periphery of the skin layer, or an end reinforcement layer pre-bent along the shape of the periphery can be configured. Particularly when using a thermosetting resin as the first matrix resin, the skin layer and the end reinforcement layer are integrated through the adhesiveness of the prepreg, thus facilitating and favoring the positioning of the end reinforcement layer.

[0132] Next, Figure 6(c) shows the feeding process. This process involves placing a mixture 90 of lightweight particles (thermally expandable particles) and a second matrix resin onto the inner surface of the skin layer 22 of one component. During the feeding process, care must be taken to prevent the mixture of lightweight particles and the second matrix resin from flowing out of the skin layer of one component beyond the end reinforcement layer. Therefore, it is preferable that the mixture does not adhere to the position in contact with the skin layer of the other component in the end reinforcement layer. By feeding the mixture of lightweight particles and the second matrix resin in a position closer to the periphery and keeping it in a position closer to the periphery, it is possible to prevent the lightweight particles from flowing out from between the end reinforcement layer and the skin layer to the surface of the flat lightweight component. Furthermore, if the mixture of lightweight particles and the second matrix resin is fed in a manner that coats the entire inner surface of the skin layer of one component, a homogeneous core layer can be obtained, which is therefore preferable.

[0133] In the feeding process, it is preferable to preheat the mixture of lightweight particles and the second matrix resin. By using this method, the viscosity of the mixture of lightweight particles and the second matrix resin is reduced, thus shortening the feeding time and making it easier to adjust the feeding amount. The mixture of lightweight particles and the second matrix resin can be preheated using an oven or microwave oven.

[0134] also, Figure 6 (d) shows the second configuration step. In this step, the skin 21 of the other is further configured on the upper surface of the skin 22 of the first, such that the end reinforcement layers 40, 41 contact at least a portion of the periphery of the skin 22 of the other. In the second configuration step, the skin of the other can be directly configured on the lower mold in a planar state, or it can be configured on the lower mold after being pre-shaped into a three-dimensional shape. Especially when a thermosetting resin is used as the first matrix resin, the skin and the end reinforcement layers are integrated by the adhesiveness of the prepreg, so the positioning of the end reinforcement layers is easy and preferred.

[0135] and, Figure 6 (e) in the diagram represents the mold-closing process, which involves closing the upper mold 81, which has been heated to the molding temperature. During this process, the skin and end reinforcement layers of one mold are pressed together with the skin of the other. The temperature of the upper mold is preferably set to the same temperature as the lower mold, but this is not a limitation in the manufacturing method of the flat, lightweight part of the present invention. Furthermore, a vacuum can be drawn into the cavity during the mold-closing process. By using this method, in addition to reducing voids in the skin and end reinforcement layers and improving the mechanical properties of the flat, lightweight part, surface bubbles can be prevented, thus resulting in a flat, lightweight part with excellent appearance quality, which is preferable. The mold-closing process is completed after the double-sided mold, including the upper and lower molds, is completely closed.

[0136] like Figure 6As shown in (f), the lightweight particles, acting as thermally expandable particles, begin to expand in volume upon reaching a specified temperature, forming a core layer. Through the expansion of the lightweight particles, the skin layer and end reinforcement layer are pressed into the mold cavity through the core layer and subjected to pressure. Then, as... Figure 6 As shown in (g), a flat, lightweight part of excellent quality can be obtained through curing and demolding.

[0137] The present invention relates to a method for manufacturing a flat, lightweight component using a double-sided mold including an upper mold and a lower mold. The method is characterized by comprising: a preparation step, wherein a prepreg blank comprising reinforcing fibers unidirectionally filamented and a first matrix resin is used to prepare a skin layer with end-reinforcing layers bonded to the periphery of one skin layer and a skin layer of another; a first placement step, wherein the aforementioned skin layer with end-reinforcing layers is placed in the aforementioned lower mold, which has been heated to the molding temperature; an input step, wherein a mixture of lightweight particles and a second matrix resin is placed on the inner surface of the aforementioned skin layer; a second placement step, wherein the aforementioned skin layer of the other skin layer is further placed in the aforementioned lower mold, such that the aforementioned end-reinforcing layers contact the periphery of the aforementioned skin layer; and a mold closing step, wherein the aforementioned upper mold, heated to the molding temperature, is closed. The manufacturing method further comprises a step of causing the aforementioned lightweight particles to expand in volume to form a core layer.

[0138] Figure 7 The process is shown in more detail. In this method, a double-sided mold with cavities shaped as flat, lightweight parts formed on the mating surfaces of the upper and lower molds is also used to mold fiber-reinforced resin.

[0139] Figure 7 (a) is a preparation process, which is a process of preparing a skin with end reinforcement layers and another skin 21 formed from a prepreg blank. The skin with end reinforcement layers is obtained by bonding end reinforcement layers 40, 41 formed from fiber-reinforced resin sheets to at least a portion of the periphery of a skin 22 formed from a prepreg blank containing reinforcing fibers unidirectionally filamentous and a first matrix resin.

[0140] The skin layer and the end reinforcement layer can be manufactured using the methods described above. A skin layer with end reinforcement layers can be manufactured by bonding the end reinforcement layers to the periphery of one of the skin layers. When using a thermosetting resin as the first matrix resin, the skin layer and the end reinforcement layer can be bonded using the adhesiveness of the prepreg blank. Alternatively, when using a thermoplastic resin as the first matrix resin, bonding can be achieved by heating the end reinforcement layer and one of the skin layers to the melting temperature of the thermoplastic resin, pressing, and cooling. Furthermore, resin adhesives or resin adhesive films can be used to bond the end reinforcement layer to one of the skin layers.

[0141] Then, Figure 7 (b) shows the first configuration step. Figure 7 (c) shows the input process, Figure 7 (d) in the diagram shows the second configuration step. Figure 7 (e) shows the mold closing process. These processes only need to be performed in conjunction with the aforementioned... Figure 6 The same method described in the text can be implemented. By going through these processes, flat and lightweight parts of excellent quality can be obtained.

[0142] In the method for manufacturing the flat, lightweight component of the present invention, a prepreg blank with notches is preferably used as the aforementioned prepreg blank. Using a prepreg blank in the skin layer easily produces fuzzing of the reinforcing fibers, which can penetrate deep into the core layer to form a strong bonding surface, thus this is preferred. Alternatively, an integral laminate of an unnotched prepreg blank and a prepreg blank with notches can be used as the skin layer. In this case, it is preferable to position the prepreg blank on the contact surface with the core layer. This arrangement allows the unnotched prepreg blank to exhibit excellent mechanical properties, and the prepreg blank with notches can firmly bond the core layer and the skin layer, thus this is a preferred method.

[0143] When using a notched prepreg blank in the end reinforcement layer, the fiber tension can be suppressed as the end reinforcement layer deforms against the end profile of the flat, lightweight component due to the expansion of the core layer. This suppresses resin enrichment and void formation, improving the appearance and mechanical properties of the end, which is preferable from this perspective. The fiber direction of the reinforcing fibers in the end reinforcement layer is preferably along the direction of the end profile of the flat, lightweight component.

[0144] In the manufacturing method of the flat, lightweight component of the present invention, it is preferable to roughen the inner surface of the skin layer of at least one component until the mold closing process is completed. In particular, roughening the reinforcing fibers of the inner surface of the skin layer of at least one component is preferred during the feeding process. By feeding the component using a spatula or similar means to coat the entire inner surface of the skin layer of one component with a mixture of lightweight particles and a second matrix resin, the reinforcing fibers of the inner surface of the skin layer can be roughened. Furthermore, by applying the mixture of lightweight particles and the second matrix resin while utilizing gravity to allow it to flow from the high to the low portion of the skin layer of one component, the reinforcing fibers of the inner surface of the skin layer can be roughened. Preheating the mixture of lightweight particles and the second matrix resin allows for efficient utilization of gravity-induced flow, which is therefore preferable. While the preheating temperature also depends on the molding temperature and the expansion start temperature of the lightweight particles, it is preferably 40°C to 180°C, more preferably 70°C to 130°C. By setting the lower limit of the preferred range above the lower limit, the viscosity of the second matrix resin is reduced, allowing the resin to flow; by setting the upper limit below the upper limit, the thermal expansion of the lightweight particles is suppressed, thus allowing sufficient time for resin coating during the input process.

[0145] The method for manufacturing the flat, lightweight component of the present invention preferably involves fuzzing the reinforcing fibers on the inner surface of the end reinforcement layer until the mold closing process is completed. In particular, if a fiber-reinforced foam is used as the end reinforcement layer, the fiber-reinforced foam is heated in the mold, causing the reinforcing fibers to fuzz due to the rebound of the reinforcing fibers contained in the fiber-reinforced foam, penetrating the core layer, thereby firmly integrating the core layer with the end reinforcement layer.

[0146] Industrial availability

[0147] The manufacturing method of the flat lightweight component involved in this invention can be applied to the manufacturing of any flat lightweight component, and the resulting flat lightweight component is suitable for use as a propeller blade structure in transportation vehicles such as aircraft, automobiles, and ships, as well as in the fields of sports and leisure.

[0148] Explanation of reference numerals in the attached figures

[0149] 1. Flat, lightweight components

[0150] 21, 22, 23 Cortex

[0151] 200 layers of dermal napping reinforcing fibers

[0152] 30 core layers

[0153] The 300-layer napped reinforcing fibers partially penetrate the fiber reinforcement portion of the core layer.

[0154] 40, 41 End reinforcement layers

[0155] 50 Enclosed Space

[0156] The outline of a 500-degree enclosed space

[0157] 81 Upper mold

[0158] 82 Lower mold

[0159] 90 Mixture

Claims

1. A flat, lightweight component, characterized in that, It comprises: a skin layer disposed on two surfaces of the flat, lightweight component; an end reinforcement layer disposed at the end of the flat, lightweight component in such a manner as to contact the two inner surfaces of the skin layer on the two surfaces; and a core layer disposed in a space surrounded by the skin layer and the end reinforcement layer in such a manner as to directly contact the inner surface of the skin layer. The skin layer comprises one or more layers containing reinforcing fibers unidirectionally filamented and a first matrix resin, the end reinforcement layer comprises fiber-reinforced resin sheets, the core layer comprises thermally expandable particles and a second matrix resin, the reinforcing fibers raised from the skin layer penetrate the core layer, and the reinforcing fibers raised from the skin layer are formed from slit prepreg blanks.

2. The flat, lightweight component as described in claim 1, characterized in that, The core layer is formed by expanding the thermally expandable particles in volume within the space surrounded by the skin layer and the end reinforcement layer.

3. The flat, lightweight component as described in claim 1 or 2, characterized in that, The fiber-reinforced resin sheet consists of reinforcing fibers unidirectionally twisted together and a first matrix resin.

4. The flat, lightweight component as described in claim 1 or 2, characterized in that, The fiber-reinforced resin sheet is a fiber-reinforced foam containing reinforcing fibers.

5. The flat, lightweight component as described in claim 1 or 2, characterized in that, Reinforcing fibers that originate from the end reinforcement layer penetrate the core layer.

6. The flat, lightweight component as described in claim 1 or 2, characterized in that, The space surrounded by the skin layer and the end reinforcement layer is a closed space.

7. The flat, lightweight component as described in claim 1 or 2, characterized in that, In the end reinforcement layer, the fiber-reinforced resin sheet has a rolled structure or a folded structure.

8. A method for manufacturing a flat, lightweight component, wherein the method uses a double-sided mold including an upper mold and a lower mold to manufacture the flat, lightweight component, the manufacturing method being characterized by having: Preparation process, among which, A skin layer of one and a skin layer of the other are prepared using a prepreg containing reinforcing fibers unidirectionally filamented and a first matrix resin, and an end reinforcement layer is prepared using fiber-reinforced resin sheets. In the first configuration step, the skin layer of the one is configured in the lower mold that has been heated to the molding temperature, and the end reinforcement layer is placed on at least a portion of the periphery of the skin layer of the one. In the input process, a mixture of thermally expandable particles and a second matrix resin is placed on the skin of one of them; In the second configuration step, the skin layer of the other is further configured on the upper surface of the skin layer of the first, such that the end reinforcement layer contacts at least a portion of the periphery of the skin layer of the other; and The mold closing process involves closing the upper mold, which has been heated to the molding temperature. The manufacturing method further includes a step of causing the thermally expandable particles to expand in volume to form a core layer. In this process, a prepreg blank with a notch is used as the prepreg blank, and until the mold closing process is completed, the skin of at least one of the prepreg blanks is roughened at a portion corresponding to the inner surface of the flat, lightweight component.

9. A method for manufacturing a flat, lightweight component, wherein the method uses a double-sided mold including an upper mold and a lower mold to manufacture the flat, lightweight component, the manufacturing method being characterized by having: Preparation process, among which, The process involves bonding an end-reinforcing layer comprising a fiber-reinforcing resin sheet to at least a portion of the periphery of a skin layer comprising a prepreg blank, preparing a skin layer with an end-reinforcing layer, and preparing a skin layer comprising the other prepreg blank, wherein the prepreg blank comprises reinforcing fibers unidirectionally filamented and a first matrix resin. The first configuration step involves configuring the skin layer with the end reinforcement layer onto the lower mold that has been heated to the molding temperature; In the input process, a mixture of thermally expandable particles and a second matrix resin is placed on the skin of one of them; In the second configuration step, the skin layer of the other is further configured on the upper surface of the skin layer with the end reinforcement layer, such that the end reinforcement layer contacts at least a portion of the periphery of the skin layer of the other; and The mold closing process involves closing the upper mold, which has been heated to the molding temperature. The manufacturing method further includes a step of causing the thermally expandable particles to expand in volume to form a core layer. In this process, a prepreg blank with a notch is used as the prepreg blank, and until the mold closing process is completed, the skin of at least one of the prepreg blanks is roughened at a portion corresponding to the inner surface of the flat, lightweight component.

10. The method for manufacturing a flat, lightweight component as described in claim 8 or 9, characterized in that, The reinforced fiber resin sheet is a prepreg containing reinforcing fibers unidirectionally filamented in parallel and a first matrix resin.

11. The method for manufacturing a flat, lightweight component as described in claim 8 or 9, characterized in that, The reinforced fiber resin sheet is a fiber-reinforced foam containing reinforcing fibers.

12. The method for manufacturing a flat, lightweight component as described in claim 8 or 9, characterized in that, Until the mold closing process is completed, the portion of the end reinforcement layer corresponding to the inner surface of the flat, lightweight component is roughened.

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