Flat lightweight component and method for manufacturing the same

Abstract

To provide a flat lightweight member formed of a fiber-reinforced resin molded article, which has excellent mechanical properties at the end portions, excellent adhesion between the core layer and the skin layer, a good appearance grade, and excellent productivity, the flat lightweight member is characterized by comprising: a skin layer composed of a woven fabric base material and a matrix resin; a bag-shaped separation layer present inside the woven fabric base material; and a mixture of the matrix resin and a heat-expandable material present inside the separation layer.

Description

TECHNICAL FIELD

[0001] The present application relates to a flat lightweight member (fiber-reinforced resin molded article) formed of a skin layer on the surface and a core layer inside, which can be used as a propeller blade, and a manufacturing method thereof. Specifically, it relates to a manufacturing method of a flat lightweight member formed of a fiber-reinforced resin molded article, which is excellent in mechanical properties of the end portion, adhesion between the core layer and the skin layer, and appearance quality, and also excellent in productivity. BACKGROUND

[0002] A fiber-reinforced resin is used in a wide range of industries because it is lightweight and has high strength and high rigidity. In particular, a molded article using a prepreg, which is an intermediate material in which a resin is impregnated in a fiber-reinforced material formed of a long fiber such as a reinforcing fiber, is suitably used. In addition, a sandwich structure material in which a skin layer is a fiber-reinforced resin and a core layer is porous is effectively used in transportation means such as aircraft, automobiles, and ships, and in the sports and leisure fields because of its lightweight and strength. As a molded article having such a sandwich structure, a molded article including a skin layer formed of a fiber-reinforced base material and a core layer formed of a thermal expansion material and a matrix resin is known.

[0003] As such a molded article, a propeller blade in which an upper surface use prepreg and a lower surface use prepreg are stacked and adhered in the thickness direction at the end portion of the molded article is known. This molded article is obtained by stacking the upper surface use prepreg in one split mold and the lower surface use prepreg in the other split mold, and disposing a foaming agent in the space formed by the two prepregs at the time of closing the mold (for example, Patent Literature 1).

[0004] In addition, as the same propeller blade, a molded article in which a main portion is composed of a skin layer and a core layer and a separation layer, a peripheral portion (a portion of the outer periphery of the propeller blade when the propeller blade is viewed from the direction of the largest projected area) is composed of a skin layer and a core layer, and reinforcing fibers are additionally disposed at the leading edge and the trailing edge of the propeller blade for reinforcement is known. This molded article, although a separation layer that inhibits the passage of the thermal expansion material is disposed between the core layer and the skin layer, separates the thermal expansion material constituting the core layer and the thermal expansion material in the matrix resin using the separation layer, and forms the skin layer by impregnating only the matrix resin in the dry reinforcing fiber base material constituting the skin layer (for example, Patent Literature 2).

[0005] In addition, as the form of the reinforcing fiber base material, a technique in which a fiber material is made into a woven fabric (braided fabric or woven braid) is also known. The woven fabric is made by combining fiber bundles in two or three directions and mechanically weaving them into a cylindrical shape or other shapes. Thereby, the fiber material can be made into a desired shape by automatic operation, so that the manufacturing efficiency of the reinforcing fiber base material can be improved.

[0006] Prior Art Documents

[0007] Patent Documents

[0008] Patent Document 1: Japanese Patent No. 6789887

[0009] Patent Document 2: Japanese Patent Application Laid-Open No. 8-276441 SUMMARY

[0010] PROBLEMS TO BE SOLVED BY THE INVENTION

[0011] However, as described above, in the case of the flat lightweight member in which the upper surface prepreg and the lower surface prepreg are laminated and bonded in the thickness direction at the end portion of the molded product, the prepreg needs to be laminated and bonded in the region at the end portion. Therefore, the prepreg having a larger specific gravity than the core layer needs to be arranged to the region which should be the core layer in order to achieve lightweight, and there is a problem that the weight of the flat lightweight member increases. In addition, based on the same reason, sometimes the shape of the flat lightweight member to which this configuration can be applied is limited. On the other hand, if a configuration in which only the end portions of the prepregs are butted against each other is formed, there is a problem that the joint strength decreases, and the foamed resin leaks to the outside of the flat lightweight member, thereby damaging the appearance and the surface quality.

[0012] In addition, in the case of the conventional flat lightweight member in which the main portion is composed of the skin layer and the core layer and the separation layer, the peripheral portion is composed of the skin layer and the core layer, and the reinforcing fiber for reinforcement is additionally arranged at the leading edge and the trailing edge, in the case where the arrangement position of the separation layer is inappropriate, peeling is likely to occur in the vicinity of the separation layer if used for a long time, and there is a problem that the core layer and the skin layer cannot be firmly integrated.

[0013] Further, in the case of the conventional method for manufacturing a fiber-reinforced resin in which the upper surface prepreg is laminated in one split mold, the lower surface prepreg is laminated in the other split mold, and the foaming agent is arranged in the space formed by the two prepregs at the time of mold clamping, it is necessary to laminate the prepreg on the surface of the mold having a three-dimensional shape at room temperature, and then to heat the mold to cure the prepreg. Not only a large amount of labor and special techniques / devices are required in the lamination process, but also a large amount of time is required for the temperature raising and lowering of the mold, and therefore there is a problem in terms of productivity.

[0014] Further, in the conventional manufacturing method of the fiber-reinforced resin in which a part of the base resin used to form the core layer is impregnated and cured in the dry reinforcing fiber base material through the separation layer to form the skin layer, in the case where the flat lightweight member is not a simple flat plate but has a three-dimensional shape, the separation layers arranged respectively on the upper and lower sides are displaced and the like during molding, so that it is difficult to obtain a flat lightweight member with high precision and small deviation. In addition, during the arrangement of the reinforcing fiber, it is difficult to position, and during molding, it is also easy to be displaced, so that the center of gravity of the flat lightweight member is sometimes changed. Furthermore, during the impregnation of the base resin in the reinforcing fiber, a bubble called void is sometimes generated at the end of the flat lightweight member, so that the mechanical properties are reduced and the appearance quality is impaired.

[0015] As described above, in the conventional technology described above, it is very difficult to obtain a flat lightweight member in which the mechanical properties up to the end of the flat lightweight member, the adhesion of the core layer and the skin layer, and the appearance quality are excellent.

[0016] Therefore, the present application aims at the above-described problems, and provides a flat lightweight member formed of a fiber-reinforced resin molded product in which the mechanical properties at the end, the adhesion of the core layer and the skin layer, and the appearance quality are excellent, and the productivity is also excellent, and a manufacturing method thereof.

[0017] Means for solving the problems

[0018] In order to solve the above problems, the present application adopts any one of the following configurations.

[0019] (1) A flat lightweight member characterized by comprising: a skin layer composed of a woven fabric base material and a base resin; a bag-shaped separation layer present inside the woven fabric base material; and a mixture of the base resin and a thermal expansion material present inside the separation layer.

[0020] (2) The flat lightweight member described in the above (1), characterized in that the woven fabric base material is composed of a fiber bundle that becomes a plurality of central yarns arranged in parallel in the same direction, and a fiber bundle that becomes a binding yarn crossing the central yarns, and the weight per unit length of the fiber bundle that becomes the central yarn used in the end region of at least one side of the flat lightweight member is smaller than the weight per unit length of the fiber bundle that becomes the central yarn used in the central region of the flat lightweight member.

[0021] (3) The flat lightweight member according to the aforementioned (1), characterized in that the woven fabric base material is composed of fiber bundles that become a plurality of central yarns arranged in parallel in the same direction, and fiber bundles that become a weaving yarn that crosses the central yarns, the weight per unit length of the fiber bundles that become the central yarns used in the end region on one side of the flat lightweight member is smaller than the weight per unit length of the fiber bundles that become the central yarns used in the central region of the flat lightweight member, and the weight per unit length of the fiber bundles that become the central yarns used in the end region on the other side of the flat lightweight member is larger than the weight per unit length of the fiber bundles that become the central yarns used in the central region of the flat lightweight member.

[0022] (4) The flat lightweight member according to any one of the aforementioned (1) to (3), characterized in that at least one rib portion including a fiber-reinforced base material is provided inside the woven fabric base material, and the separation layer and the mixture are respectively present in a plurality of regions inside the woven fabric base material separated by the rib portion.

[0023] (5) The flat lightweight member according to the aforementioned (4), characterized in that the rib portion includes a fiber-reinforced base material, and a foamed body and / or a resin block arranged inside the fiber-reinforced base material.

[0024] (6) A manufacturing method of a flat lightweight member, characterized in that the manufacturing method includes:

[0025] a woven fabric base material production step in which a woven fabric base material constituting a skin layer is produced;

[0026] a separation layer arrangement step in which a bag-shaped separation layer having a shape corresponding to the outer shape of the flat lightweight member is arranged inside the woven fabric base material;

[0027] a feeding step in which a mixture of a base resin and a heat-expandable material is fed inside the separation layer;

[0028] a step of arranging the woven fabric base material inside which the separation layer and the mixture are arranged in the cavity of a lower mold that has been heated to a molding temperature;

[0029] a mold closing step in which an upper mold that has been heated to a molding temperature is closed and the cavity is evacuated; and

[0030] an expansion step in which the heat-expandable material is expanded, and the woven fabric base material and the separation layer and the mixture are integrated.

[0031] (7) A manufacturing method of a flat lightweight member having at least one rib portion, characterized in that the manufacturing method includes:

[0032] A woven fabric base material manufacturing step in which a woven fabric base material constituting a skin layer is manufactured;

[0033] A fiber reinforced base material preparation step in which a fiber reinforced base material constituting a rib portion is prepared;

[0034] A rib arrangement step in which the fiber reinforced base material constituting the rib portion is arranged inside the woven fabric base material, and the inside of the woven fabric base material is partitioned into two or more spaces;

[0035] A separation layer arrangement step in which a bag-shaped separation layer is arranged in the two or more spaces, the bag-shaped separation layer having a shape corresponding to the shape of the two or more spaces;

[0036] A mixture input step in which a mixture of a matrix resin and a heat-expandable material is input into the inside of the separation layer;

[0037] A material arrangement step in which the woven fabric base material in which the separation layer, the mixture, and the fiber reinforced base material constituting the rib portion are arranged inside is arranged on a lower mold that has been heated to a molding temperature;

[0038] A mold closing step in which an upper mold that has been heated to a molding temperature is closed, and the mold cavity is vacuumed; and

[0039] An expansion step in which the heat-expandable material is expanded, and the woven fabric base material and the separation layer and the mixture and the fiber reinforced base material constituting the rib portion are integrated.

[0040] (8) The flat lightweight member manufacturing method described in the above (7), characterized in that the rib portion is constituted by a fiber reinforced base material, and a foam and / or wood arranged inside the fiber reinforced base material.

[0041] (9) The flat lightweight member manufacturing method described in any one of the above (6) to (8), characterized in that, in the woven fabric base material manufacturing step, the woven fabric base material is constituted by a fiber bundle that becomes a plurality of central yarns arranged in parallel in the same direction, and a fiber bundle that becomes a weaving yarn that crosses the central yarns, and a fiber bundle that becomes a central yarn is used in at least one end region of the flat lightweight member that is smaller than a fiber bundle that becomes a central yarn in a central region of the flat lightweight member.

[0042] (10) The manufacturing method of the flat lightweight member according to any one of the preceding (6) to (8), characterized in that, in the preceding woven fabric base material manufacturing step, the woven fabric base material is constituted of fiber bundles that become the plurality of central yarns arranged in parallel in the same direction, and fiber bundles that become the weft yarns crossing the central yarns, and a fiber bundle that becomes the central yarn in an end region on one side of the flat lightweight member is used that is smaller than a fiber bundle that becomes the central yarn in a central region of the flat lightweight member, and a fiber bundle that becomes the central yarn in an end region on the other side of the flat lightweight member is used that is larger than the fiber bundle that becomes the central yarn in the central region of the flat lightweight member.

[0043] (11) The manufacturing method of the flat lightweight member according to any one of the preceding (6) to (10), characterized in that the fiber bundles that become the central yarns and the fiber bundles that become the weft yarns constituting the woven fabric base material are all dry fiber bundles.

[0044] (12) The manufacturing method of the flat lightweight member according to any one of the preceding (6) to (10), characterized in that the fiber bundles that become the central yarns and the fiber bundles that become the weft yarns constituting the woven fabric base material are all prepregs containing resin.

[0045] Effects of the Invention

[0046] According to the flat lightweight member and the manufacturing method thereof according to the present invention, a flat lightweight member formed of a fiber-reinforced resin molded product, which is excellent in appearance quality, productivity, and the like, and which is excellent in mechanical properties of the end portions, and adhesion between the core layer and the skin layer, can be obtained. BRIEF DESCRIPTION OF DRAWINGS

[0047] [ Figure 1 ] is a plan view (a) and a sectional view (b) at A-A' of an example of a flat lightweight member obtained by the manufacturing method according to the present invention.

[0048] [ Figure 2 ] is a plan view (a) and sectional views (b) to (d) at A-A' of an example of a flat lightweight member obtained by the manufacturing method according to the present invention.

[0049] [ Figure 3 ] is a perspective plan view showing a shape example of a separation layer of the flat lightweight member shown in (b) in Figure 2 Figure 2

[0050] [ Figure 4 ] is a view showing each step in the manufacturing method of the flat lightweight member according to the present invention.

[0051] [ Figure 5 ] is a schematic view showing an example of a basic weft knitting stitch of a woven fabric base material.​​

[0052] [ Figure 6 ]is a plan view (a) showing the outline of only the woven fabric base material in the flat lightweight member of the present application and a partially enlarged schematic view (b) of the plan view (a). DETAILED DESCRIPTION

[0053] Hereinafter, the present application will be described in detail with reference to the accompanying drawings and embodiments.

[0054] The manufacturing method of the flat lightweight member according to the present application is characterized by comprising:

[0055] a woven fabric base material production step in which a woven fabric base material constituting a skin layer is produced;

[0056] a separation layer arrangement step in which a bag-shaped separation layer having an outer shape of the aforementioned flat lightweight member is arranged inside the aforementioned woven fabric base material;

[0057] a feeding step in which a mixture of a base resin and a heat-expandable material is fed inside the aforementioned separation layer;

[0058] a step of arranging the aforementioned woven fabric base material having the aforementioned separation layer and the aforementioned mixture arranged inside, on a lower mold heated to a molding temperature;

[0059] a mold closing step in which an upper mold heated to a molding temperature is closed and a cavity is vacuumed; and

[0060] an expansion step in which the aforementioned heat-expandable material is expanded to integrate the aforementioned woven fabric base material and the aforementioned separation layer and the aforementioned mixture.

[0061] In the manufacturing method of the flat lightweight member, by setting the base material constituting the skin layer as a woven fabric base material, continuity of fibers at both end portions in a direction crossing the length direction of the flat lightweight member can be maintained, and thus peeling or the like at the end portions can be eliminated. In addition, by setting the separation layer as a bag shape having the outer shape of the flat lightweight member, displacement of the separation layer at the time of molding can be prevented, and outflow of the heat-expandable material to the surface layer can be prevented. Thus, the surface quality becomes good, and generation of voids can be prevented, and thus deterioration of the end portion strength can be prevented.

[0062] Figure 1 One embodiment of the flat lightweight member obtained by the manufacturing method of the present application is shown.

[0063] Figure 1 In (a) in the above, 1 indicates a plan view of the flat lightweight member, the right side of the paper is a front end portion a, and the left side of the paper is a root portion b. The A-A' cross section of the flat lightweight member 1 (i.e., the cross section of the flat lightweight member 1 in a direction crossing the length direction) is shown inFigure 1 (b) In this context, the flat, lightweight component 1 is mainly formed by a skin layer 21, a core layer 30, and a separation layer 40.

[0064] Figure 4 The following describes each step in the manufacturing method of the flat, lightweight component of the present invention. The step of molding fiber-reinforced resin using a double-sided mold with cavities having the shape of a flat, lightweight component formed on the mating surfaces of the upper mold 81 and the lower mold 82 is shown. Each step will be described sequentially below. It should be noted that... Figure 4 (a) in the text indicates the process of making the woven fabric substrate. Figure 4 (b) in the text represents the separation layer configuration process. Figure 4 (c) in the text indicates the input process involving a mixture of matrix resin and thermally expandable material. Figure 4 In this context, (d) indicates the process of preparing the woven fabric substrate, which includes the release layer and the mixture. Figure 4 (e) in the text indicates the mold closing process. Figure 4 In this context, (f) represents the expansion process of thermally expandable materials. Figure 4 In this context, (g) represents a flat, lightweight component obtained through a demolding process.

[0065] Woven fabric substrate manufacturing process ( Figure 4 (a) in

[0066] In this invention, the leather layer is composed of at least one layer of woven fabric substrate 100. Figure 5 The diagram shows a schematic of the basic braiding structure of the woven fabric substrate 100. The woven fabric substrate 100 refers to a fiber substrate obtained by weaving reinforcing fiber bundles using a braiding machine. It is manufactured by mechanically braiding the fiber bundles into a three-dimensional shape, such as a cylinder, using braided yarns in only two directions, or in three directions including a central yarn in addition to the braided yarns. When using a braiding machine, the woven fabric substrate can be layered while adjusting the braiding angle θ of the fiber bundles. Furthermore, since there are no slits in the reinforcing fibers other than the longitudinal ends of the hollow woven fabric substrate, a lighter, more rigid, and stronger molded product can be obtained. Moreover, by using a core with the desired flat and lightweight component shape, a woven fabric substrate pre-formed to the product shape (e.g., ...) can be manufactured. Figure 4 The woven substrate 100 with the shape shown in (a) can thus improve production efficiency.

[0067] Multiple layers of woven fabric substrates can be stacked as needed. Furthermore, when the cross-sectional shape of the core varies along its length, the mesh size can be controlled by increasing the knot angle in areas with a longer cross-sectional perimeter and decreasing the knot angle in areas with a smaller cross-sectional perimeter during fiber bundling. This allows for the production of woven fabric substrates with small mesh gaps. Conversely, to maintain a constant knot angle, the mesh gaps can be reduced by using smaller fiber bundles (the number of individual yarns constituting each bundle) and stacking multiple layers of woven fabric substrates. Therefore, the details of the woven fabric substrate can be designed according to the performance requirements of the product.

[0068] The core used in the fabrication of woven fabrics is preferably made by dividing it into at least two parts. This makes it easy to remove the core from the fabric substrate after it has been made.

[0069] Reinforcing fibers used as the base material for woven fabrics 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 reinforcing fibers, 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 where lightweighting is desired. PAN-based carbon fibers, which are readily available for high-strength production, are preferred.

[0070] In this invention, the thickness of the skin layer 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. This thickness can be set by taking into account the balance between strength and lightweight required for flat, lightweight components.

[0071] Separation layer configuration process ( Figure 4 (b)

[0072] In this invention, a separation layer is disposed inside the woven substrate obtained through the aforementioned woven substrate manufacturing process. The separation layer is bag-shaped, having the form of a flat, lightweight component. This shape prevents the separation layer from shifting during the molding of the flat, lightweight component, and by preventing thermally expanding materials from flowing to the surface, the surface finish is improved, and voids are prevented. Furthermore, it reduces the occurrence of resin enrichment at the ends of the flat, lightweight component.

[0073] As a separation layer, a thin sheet with a separation function is used that allows resin to pass through but prevents thermally expanding materials from passing through. For example, thin non-woven or woven fabric sheets with small mesh openings, porous films such as polyethylene and polypropylene, are suitable; two or more of these can also be used together. The size of the mesh openings is selected based on the type and expansion properties of the thermally expanding materials, ensuring that they cannot pass through. Furthermore, materials that inherently function as reinforcing materials, such as glass fiber, carbon fiber, and aramid fiber, can also be used as the separation layer.

[0074] For the separation layer, a separation layer having the desired shape of a flat, lightweight component is used. Here, "shape of the flat, lightweight component" can be exactly the same shape as the flat, lightweight component, or it can be an affine transformation shape of the flat, lightweight component, or an offset shape of the flat, lightweight component offset in the thickness direction. Furthermore, the size of the separation layer can be the same as the flat, lightweight component, or it can be a different size. In the case of a different size, for example, it is preferable to use the aforementioned affine transformation or offset to set only one coordinate of the orthogonal coordinate system, or two or more coordinates, to 80% to 150% of the original size of the flat, lightweight component. That is, the separation layer in this invention uses a shape corresponding to the desired shape of the flat, lightweight component.

[0075] [The process of adding a mixture of matrix resin and thermally expandable material ( Figure 4 (c)

[0076] Next, as described above, a thermally expanding material and a matrix resin are introduced into the interior of the release layer disposed within the woven fabric substrate. The core layer is formed from these thermally expanding materials and the matrix resin (hereinafter referred to as the first matrix resin).

[0077] With respect to the weight ratio of the heat expandable material in the core layer to the first base, when the weight of the first base resin is set to 100%, it is preferable that the heat expandable material be set to a range of 5% or more and 100% or less, and more preferably to a range of 10% or more and 40% or less. By setting the weight of the heat expandable material to 5% or more, the specific gravity of the core layer becomes small, and it is easy to exhibit lightness. Also, by being 10% or more, it is possible to reduce local "resin concentration" that occurs due to separation of the first base resin and the heat expandable material, and thus the core layer has a more homogeneous structure, and it is possible to reduce deviation of the center of gravity. On the other hand, by being 100% or less, it is possible to have the first base resin exist between the heat expandable materials, and crosslink the heat expandable materials to each other, and the core layer becomes rigid, and it is possible to maintain the shape. Note that in the case of being greater than 100%, the crosslinking of the heat expandable materials to each other is insufficient, and thus the core layer becomes brittle, and the shape becomes easy to deform. Also, by being 40% or less, it is possible for the first base resin to cover around the heat expandable material, and thus generation of cracks in the core layer is suppressed, and it is possible to maintain the mechanical properties of the core layer for a long period of time.

[0078] [Base Resin]

[0079] As the first base resin in the present application, for example, thermosetting resins such as epoxy resins, unsaturated polyester resins, vinyl ester resins, phenol resins, epoxy acrylate resins, urethane acrylate resins, phenoxy resins, alkyd resins, urethane resins, maleimide resins, cyanate ester resins, and the like; thermoplastic resins such as polyamide resins, polyacetal resins, polyacrylate resins, polysulfone resins, acrylonitrile-butadiene-styrene copolymer (ABS) resins, polyester resins, acrylic resins, polybutylene terephthalate (PBT) resins, polyethylene terephthalate (PET) resins, polyethylene resins, polypropylene resins, polyphenylene sulfide (PPS) resins, polyether ether ketone (PEEK) resins, liquid crystal polymers, fluorine-based resins such as chlorovinyl and polytetrafluoroethylene, silicone resins, and the like. Note that among these, it is particularly preferable to use a thermosetting resin. By making the first base resin a thermosetting resin, the cured base resin covers around the heat expandable material of the core layer, and forms a porous structure, and thus it is possible to prevent deformation and expansion of the core layer even in the case where the fiber-reinforced resin molded product is heated.

[0080] [Heat Expandable Material]

[0081] The heat expandable material used in the present application refers to heat expandable resin particles that undergo volume expansion by being heated and warmed at the time of molding, and heat expandable materials that are already in a heat expanded state but can be compressed by being pressurized.

[0082] If the heat-expandable material is mixed with the first base resin and heated, volume expansion occurs, and in the case where the first base resin is a thermosetting resin, a lightweight porous structure core layer is formed by curing of the thermosetting resin. Also, in the case where the first base resin is a thermoplastic resin, upon cooling, a lightweight porous structure core layer is formed by solidification of the molten thermoplastic resin or by adhesion of the softened thermoplastic resin.

[0083] The volume expansion ratio α (%) of the mixture of the heat-expandable material and the first base resin is represented by the following equation (1) when the volume of the mixture before expansion is taken as V1 (cm 3 ) and the volume after expansion is taken as V2 (cm 3 ).

[0084] α = 100 x (V2 - V1) ÷ V1... (1)

[0085] This volume expansion ratio α varies depending on the weight ratio of the heat-expandable material to the first base resin and the heating conditions at the time of molding, but is preferably in the range of 30% or more and 2000% or less.

[0086] As the heat-expandable material, polyacrylonitrile-based copolymers, polymethacrylonitrile-based copolymers, polyvinylidene chloride-based copolymers, polystyrene or polystyrene-based copolymers, polyolefins, polyphenylene ether-based copolymers, and the like can be given, and capsules that internally enclose a heat-expandable gas are preferable. In particular, for a heat-expandable material that uses a low-boiling hydrocarbon as the heat-expandable gas, the volume expansion ratio is large and the core layer can be molded to be lightweight, and thus is preferable.

[0087] The size of the heat-expandable particles is preferably an average particle diameter before volume expansion in the range of 1 μm to 1 mm. By making the average particle diameter 1 μm or more, the leakage of the heat-expandable material to the surface of the fiber-reinforced resin molded product due to resin flow at the time of molding can be suppressed. Also, by being 1 mm or less, even in the case where the core layer has a thin-walled portion, the heat-expandable material invades into this portion, and thus in addition to being able to make the core layer lightweight, density unevenness of the heat-expandable particles and the first base resin in the core layer can be alleviated.

[0088] As such a heat-expandable material, "Matsumoto Microsphere" (registered trademark) manufactured by Matsumoto Yushi Pharm Co., Ltd., "Expancel" (registered trademark) manufactured by Nobel Industries Japan K.K., "Eslen Beads" manufactured by Sekisui Chemical Co., Ltd., and the like can be given, but the present application is not limited to these products.

[0089] In the present application, one kind of thermal expansion material can be used alone, or a plurality of kinds of thermal expansion materials can be mixed and used. In addition, the thermal expansion material can be used alone, or can be mixed with particles that do not thermally expand, such as glass beads.

[0090] In the inputting step of inputting the mixture of the resin and the thermal expansion material into the inside of the separation layer, the mixture of the thermal expansion material and the first base resin is preferably preheated. By using such a method, since the viscosity of the mixture of the thermal expansion material and the first base resin is reduced, the inputting time can be shortened, and the inputting amount can be easily adjusted. The mixture of the thermal expansion material and the first base resin can be preheated using an oven or a microwave oven. In addition, after the resin and the thermal expansion material are inputted into the inside of the separation layer, the end portion of the separation layer can be sealed with a heat sealer or the like, or can be folded several times. By this step, the thermal expansion material can be prevented from flowing out from the separation layer.

[0091] [Arranging the woven fabric substrate including the separation layer and the mixture in a mold (arranging step (d) in (c)] Figure 4

[0092] In the present application, next, the woven fabric substrate obtained in the aforementioned inputting step, in which the separation layer and the mixture are present in the inside, is arranged in a lower mold. The molding temperature set as the temperature of the lower mold also depends on the kind of the first base resin, but in the case where a thermosetting resin is used, a temperature in the range of 80°C or higher and 230°C or lower is preferred. By being 80°C or higher, the reaction of the base resin can be promoted, and by being 230°C or lower, the decomposition of the base resin can be suppressed. According to the manufacturing method of the fiber-reinforced resin of the present application, since the mold does not need to be subjected to temperature raising and lowering, the manufacturing time can be shortened compared to the conventional method in which the mold is subjected to temperature raising and lowering. In addition, since the woven fabric substrate is previously formed to follow the three-dimensional shape of the product, the positioning can be relatively easy.

[0093] [Closing the mold (e) in (c) to (f) and demolding step (g)] Figure 4 Figure 4

[0094] Next, the upper mold, which has been heated to the molding temperature, is closed with respect to the lower mold in which the woven fabric substrate in which the separation layer and the mixture are present in the inside is arranged in the aforementioned step. By the closing step, the mold cavity having the shape of the desired flat and lightweight member becomes airtight, and air is discharged, so that the mold cavity is evacuated.

[0095] The temperature of the upper mold is preferably set to the same temperature as the temperature of the lower mold, but is not limited thereto in the present application.

[0096] ​​​Then, the cavity is made vacuum by discharging air from the mold, and the heat-expandable material starts to expand after reaching a predetermined temperature to form a core layer. By the expansion of the heat-expandable material, the first base resin permeates the separation layer, impregnates the skin layer, is pressed into the mold cavity, and is pressurized, so that a fiber-reinforced resin molded product of excellent quality can be obtained.

[0097] In the present application, by performing such a mold closing process, in addition to being able to reduce voids in the skin layer and improve the mechanical properties of the flat lightweight member, it is also possible to prevent the occurrence of bubbles on the surface, and to obtain a flat lightweight member formed of a fiber-reinforced resin molded product that has excellent appearance quality.

[0098] [Further preferred embodiments of the present application]

[0099] The woven fabric base material in the present application is preferably composed of a fiber bundle that becomes a plurality of central yarns arranged in parallel in the same direction, and a fiber bundle that becomes a weaving yarn that crosses the central yarns, and the size of the fiber bundle of the central yarn used is different in the central region and the end region in the cross section in the direction that crosses the length direction of the flat lightweight member, and in particular, it is preferable that the fiber bundle that becomes the central yarn used in the end region of at least one side of the flat lightweight member be smaller than the fiber bundle that becomes the central yarn used in the central region of the flat lightweight member.

[0100] Figure 6 is a plan view (a) showing only the outline of the woven fabric base material in the case where it is formed into a flat lightweight member, and a schematic view (b) of the fiber bundle weaving form in the case where a part of the plan view (a) is observed from the side. The schematic view shown here is an example, and the number of fiber bundles used is not limited to this. In this flat lightweight member, the central yarn 72 of the end region 90 is composed of a smaller fiber bundle than the central yarn 71 used in the central region 80. From the viewpoint of energy efficiency, in the case where the shape of the end of at least one side of the flat lightweight member is a pointed shape, the central yarn of this end region is preferably a small fiber bundle. By this, by arranging an appropriate amount of reinforcing fibers at the end, it is possible to prevent peeling during manufacture, and even in the case where dry fibers are used, it is possible to prevent the occurrence of unimpregnated resin portions in the flat lightweight member.

[0101] Here, as described above, the end region of the relatively small fiber bundle is preferably a region from the end of the flat lightweight member to a position 5 times the skin thickness away in the cross section of the flat lightweight member in the direction intersecting the length direction. More preferably, it is a region from the end of the flat lightweight member to a position 10 times the skin thickness away. Further preferably, it is a region from the end of the flat lightweight member to a position 20 times the skin thickness away. On the other hand, the central region of the relatively large fiber bundle is preferably a region in the range of ±30% from the central position in the length direction of the cross section of the flat lightweight member in the direction intersecting the length direction.

[0102] As a method of making the fiber bundle small, there are a method of reducing the number of single yarns constituting the fiber bundle, a method of using a fiber bundle of which the single yarns are thin (small in single yarn diameter), a method of using a fiber bundle of which the single yarns are thick (large in single yarn diameter) and reducing the number of single yarns, and the like, but the present application is not limited thereto, and a plurality of methods or a plurality of fibers can be combined.

[0103] On the other hand, the woven fabric base material in the present application is preferably composed of a fiber bundle that becomes a plurality of central yarns arranged in parallel in the same direction, and a fiber bundle that becomes a weaving yarn intersecting the aforementioned central yarns, and the fiber bundle that becomes the central yarn used in the end region of at least one side of the flat lightweight member is larger than the fiber bundle that becomes the central yarn used in the central region of the flat lightweight member.

[0104] Figure 6 In the illustrated flat lightweight member, the central yarn 73 of the end region 91 is composed of a larger fiber bundle than the central yarn 71 used in the central region 80. In the case where the shape of the end of at least one side of the flat lightweight member is a round shape having a thickness compared to the other portions, by using a large fiber bundle as the central yarn of the end region, the end strength can be improved. According to such a method, compared to the case where other reinforcing materials are additionally arranged, positional deviation is less likely to occur, and thus a molded product with less deviation and stability can be obtained.

[0105] Note that, as described above, for the end region where the relatively large fiber bundle is arranged, it is preferably a region from the end of the flat lightweight member to a position 5 times the skin layer thickness away in the cross section of the flat lightweight member in the direction intersecting the length direction. More preferably, it is a region from the end of the flat lightweight member to a position 10 times the skin layer thickness away. Further preferably, it is a region from the end of the flat lightweight member to a position 20 times the skin layer thickness away. On the other hand, the central region where the relatively small fiber bundle is arranged is preferably a region in the range of ±30% from the central position in the length direction of the cross section of the flat lightweight member in the direction intersecting the length direction.

[0106] Here, as a method of making the fiber bundle large, a method of increasing the number of single yarns constituting the fiber bundle, using a fiber bundle of which the single yarns are thick (single yarn diameter is thick), and increasing the number of single yarns by using a fiber bundle of which the single yarns are thin (single yarn diameter is small) and increasing the number of single yarns, and the like can be given, but is not limited thereto, and a plurality of methods or a plurality of fibers can also be combined.

[0107] Further, in the present application, the fiber bundle used as the central yarn in the end region on one side of the flat lightweight member is smaller than the fiber bundle used as the central yarn in the central region of the flat lightweight member, and the fiber bundle used as the central yarn in the end region on the other side of the flat lightweight member is larger than the fiber bundle used as the central yarn in the central region of the flat lightweight member. In the case where the shape of the end on one side is a sharp shape and the shape of the end on the other side is a round shape having a thickness compared to the other portions, by using a fiber bundle smaller than the fiber bundle used as the central yarn in the central region of the flat lightweight member in the end region of the sharp shape, and using a fiber bundle larger than the fiber bundle used as the central yarn in the central region of the flat lightweight member in the end region of the round shape, the strength of both ends can be improved, and the end on one side having a sharp shape can be prevented from not containing the resin.

[0108] In the present application, both the fiber bundle used as the central yarn and the fiber bundle used as the knitting yarn constituting the knitted fabric substrate are preferably dry fiber bundles. In this case, the processability in the knitting machine is good, and the knitted fabric substrate can be stably produced.

[0109] On the other hand, the fiber bundle that becomes the central yarn constituting the braided fabric base material and the fiber bundle that becomes the braided yarn are each preferably a prepreg containing a resin. In this case, the shape stability of the braided fabric base material can be further improved. As the second base resin used in this prepreg, for example, a thermosetting resin such as an epoxy resin, an unsaturated polyester resin, a vinyl ester resin, a phenol resin, an epoxy acrylate resin, a urethane acrylate resin, a phenoxy resin, an alkyd resin, a urethane resin, a maleimide resin, a cyanate ester resin, and the like; a thermoplastic resin such as a polyamide resin, a polyacetal resin, a polyacrylate resin, a polysulfone resin, an acrylonitrile-butadiene-styrene copolymer (ABS) resin, a polyester resin, an acrylic resin, a polybutylene terephthalate (PBT) resin, a polyethylene terephthalate (PET) resin, a polyethylene resin, a polypropylene resin, a polyphenylene sulfide (PPS) resin, a polyether ether ketone (PEEK) resin, a liquid crystal polymer, a vinyl chloride resin, a polytetrafluoroethylene fluorine-based resin, a silicone resin, and the like. Among these, a thermosetting resin is particularly preferable.

[0110] In addition, another preferred production method of the present application is as follows. That is,

[0111] A method for producing a flat lightweight member having at least one rib portion, characterized by comprising:

[0112] A braided fabric base material production step in which a braided fabric base material constituting a skin layer is produced;

[0113] A preparation step in which a fiber-reinforced base material constituting a rib portion is prepared;

[0114] A rib arrangement step in which the fiber-reinforced base material constituting the rib portion is arranged inside the braided fabric base material, and the inside of the braided fabric base material is divided into two or more spaces;

[0115] A separation layer arrangement step in which a bag-shaped separation layer is arranged in the two or more spaces, the bag-shaped separation layer having the shape of the two or more spaces;

[0116] A pouring step in which a mixture of a base resin and a heat-expandable material is poured into the inside of the separation layer;

[0117] A material arrangement step in which the braided fabric base material in which the separation layer, the mixture, and the fiber-reinforced base material constituting the rib portion are arranged inside is arranged on a lower mold that has been heated to a molding temperature;

[0118] A mold closing step in which an upper mold that has been heated to a molding temperature is closed, and the mold cavity is vacuumed; and

[0119] an expanding step of expanding the aforementioned heat-expandable material to integrate the aforementioned woven fabric base material and the aforementioned separation layer and the aforementioned mixture and the fiber reinforced base material constituting the aforementioned rib.

[0120] By this configuration, continuity of the fibers at both end portions in the direction intersecting the length direction of the flat lightweight member is maintained, and peeling at the end portions can be prevented. In addition, by providing the separation layer in a bag shape having a space divided by the fiber reinforced base material constituting the rib, displacement of the separation layer at the time of molding can be prevented, and outflow of the heat-expandable material to the surface layer can be prevented, and a flat lightweight member with a good surface finish can be obtained. Furthermore, since generation of voids can be prevented, deterioration of the strength at the end portions can be prevented. In addition, according to the present mode, a flat lightweight member with a rib having higher strength can be obtained simply and with good productivity.

[0121] The shape of the separation layer can be the same shape as the space divided by the fiber reinforced base material, or an affine transformed shape obtained by affine transformation of the divided space, or a biased shape obtained by biasing the divided space in the thickness direction. In addition, the size of the separation layer can be the same size as the divided space, or a different size. In the case of a different size, for example, it is preferable to set only one coordinate, or two or more coordinates of the orthogonal coordinate system to be 80% or more to 150% or less of the size of the original divided space by the aforementioned affine transformation or biasing. That is, in the present application, the separation layer only needs to have a shape corresponding to the outer shape of the desired flat lightweight member.

[0122] Figure 2 、 Figure 3 One embodiment of the flat lightweight member obtained by the manufacturing method is shown. Figure 2 (a) of FIG. 1 shows a plan view of the flat lightweight member, and the right side of the paper is the front end portion a, and the left side of the paper is the root portion b. The A-A' cross section of the flat lightweight member 1 is shown in Figure 2 (b) to Figure 2 (d) of FIG. 1. Figure 2 (b) of FIG. 1 shows a case with one rib, Figure 2 (c) of FIG. 1, Figure 2 (d) of FIG. 1 shows a case with two ribs. Also, respectively, Figure 3 (a) of FIG. 1 is a plan view of the flat lightweight member corresponding to Figure 2 (b) of FIG. 1 is a plan view of the flat lightweight member corresponding to Figure 3 (b) of FIG. 1 is a plan view of the flat lightweight member corresponding to Figure 2 (c) of FIG. 1, Figure 2 (d) of FIG. 1, and shows the shape of the separation layer.

[0123] In this manufacturing method, the ribs can be easily formed according to the required rigidity and strength of the component. The fiber reinforcement substrate constituting the ribs can be the same woven substrate as the skin layer; alternatively, the aforementioned prepreg blank can also be used. Furthermore, as... Figure 2 As shown in (d), a core material 34 pre-formed into a desired shape can also be disposed inside the fiber-reinforced substrate constituting the rib. By forming the rib with the core material and the fiber-reinforced substrate disposed around the core material 34, the position of the rib can be stabilized during molding. As the core material 34, foam, resin blocks, wood, etc. can be used; from the viewpoint of lightweighting, foam is preferred. As materials for foams and resin blocks, various thermosetting resins can be used, including 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, 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 polymers, vinyl chloride resin, polytetrafluoroethylene (PTFE) and other fluorinated resins, and silicone resins and other thermoplastic resins. Molding methods for core materials include injection molding in a mold and 3D printing.

[0124] Industrial availability

[0125] This invention can be applied to the manufacture of flat, lightweight components formed from any sheet-like fiber-reinforced resin molded articles. Furthermore, the flat, lightweight components obtained by this invention are suitable for use, for example, as propeller blade structures in transportation vehicles such as aircraft, automobiles, and ships, as well as in the sports and leisure fields.

[0126] Explanation of reference numerals in the attached figures

[0127] 1 Flat Lightweight Component

[0128] 21, 22, 23 cortex

[0129] Core layers 30, 31, 32, and 33

[0130] 34-core material

[0131] 35 Mixture

[0132] Separation layers 40, 41, 42, 43, 44, 45, 46, 47

[0133] Fiber-reinforced substrates that form the ribs: 50, 51, and 52

[0134] 60, 61 braiding yarn

[0135] 70, 71, 72, 73 central yarn

[0136] 80 central region

[0137] 81 upper mold

[0138] 82 lower mold

[0139] 90, 91 end region

[0140] 100 knitted fabric base material

[0141] X width direction

[0142] Y length direction

[0143] a front end

[0144] b root

Claims

1. A flat lightweight component, characterized in that The skin layer includes a woven fabric base material and a matrix resin, a bag-shaped separation layer present inside the woven fabric base material, and a mixture of a matrix resin and a heat-expandable material present inside the separation layer. The woven fabric base material is composed of fiber bundles that become a plurality of central yarns arranged in parallel in the same direction and fiber bundles that become weft yarns crossing the central yarns, and the weight per unit length of the fiber bundles that become the central yarns used in the end region of at least one side of the flat lightweight member is smaller than the weight per unit length of the fiber bundles that become the central yarns used in the central region of the flat lightweight member.

2. The flat lightweight component of claim 1, wherein, The woven fabric base material is composed of fiber bundles that become a plurality of central yarns arranged in parallel in the same direction and fiber bundles that become weft yarns crossing the central yarns, and the weight per unit length of the fiber bundles that become the central yarns used in the end region of at least one side of the flat lightweight member is smaller than the weight per unit length of the fiber bundles that become the central yarns used in the central region of the flat lightweight member.

3. The flat lightweight component according to claim 1 or 2, characterized in that The woven fabric base material has at least one rib portion including a fiber-reinforced base material inside the woven fabric base material, and the separation layer and the mixture are present in a plurality of regions inside the woven fabric base material separated by the rib portion.

4. The flat lightweight component of claim 3, wherein, The rib portion includes a fiber-reinforced base material, and a foam and / or a resin block arranged inside the fiber-reinforced base material.

5. A method of manufacturing a flat lightweight component, characterized by The manufacturing method includes: a woven fabric base material manufacturing step in which a woven fabric base material constituting a skin layer is manufactured; a separation layer arrangement step in which a bag-shaped separation layer is arranged inside the woven fabric base material, the bag-shaped separation layer having a shape corresponding to the outer shape of the flat lightweight member; a mixture input step in which a mixture of a matrix resin and a heat-expandable material is input inside the separation layer; a woven fabric base material arrangement step in which the woven fabric base material having the separation layer and the mixture arranged inside is arranged in a cavity of a lower mold heated to a molding temperature; a mold closing step in which an upper mold heated to a molding temperature is closed and the cavity is vacuumed; and an expansion step in which the heat-expandable material is expanded, and the woven fabric base material and the separation layer and the mixture are integrated, In the woven fabric base material manufacturing step, the woven fabric base material is composed of fiber bundles that become a plurality of central yarns arranged in parallel in the same direction and fiber bundles that become weft yarns crossing the central yarns, and fiber bundles that become the central yarns used in the end region of at least one side of the flat lightweight member are smaller than fiber bundles that become the central yarns used in the central region of the flat lightweight member.

6. The method of manufacturing a flat lightweight component according to claim 5, wherein In the woven fabric base material manufacturing step, fiber bundles that become the central yarns used in the end region of the other side of the flat lightweight member are larger than fiber bundles that become the central yarns used in the central region of the flat lightweight member.

7. The method of manufacturing a flat lightweight member according to claim 5 or 6, characterized by, The fiber bundles that become the central yarns and the fiber bundles that become the weft yarns constituting the woven fabric base material are dry fiber bundles.

8. The method of manufacturing a flat lightweight member according to claim 5 or 6, characterized by, The fiber bundles that become the central yarns and the fiber bundles that become the weft yarns constituting the woven fabric base material are prepregs including a resin.

9. A method of manufacturing a flat lightweight component having at least one rib, characterized in that, The manufacturing method includes: a woven fabric base material manufacturing step in which a woven fabric base material constituting a skin layer is manufactured; a preparation step in which a fiber-reinforced base material constituting a rib portion is prepared; a rib configuring step in which a fiber reinforced base material constituting the rib is arranged inside the woven fabric base material, and the inside of the woven fabric base material is partitioned into two or more spaces; a separation layer arranging step in which a bag-shaped separation layer having a shape corresponding to the shape of the two or more spaces is arranged in the two or more spaces; a feeding step in which a mixture of a base resin and a heat-expandable material is fed into the inside of the separation layer; a material arranging step in which the woven fabric base material in which the separation layer, the mixture, and the fiber reinforced base material constituting the rib are arranged inside is arranged on a lower mold that has been heated to a molding temperature; a mold closing step in which an upper mold that has been heated to a molding temperature is closed, and the inside of a mold cavity is vacuumed; and an expanding step in which the heat-expandable material is expanded, and the woven fabric base material and the separation layer and the mixture and the fiber reinforced base material constituting the rib are integrated.

10. The method of manufacturing a flat lightweight component according to claim 9, wherein The rib is constituted by a fiber reinforced base material, and a foam and / or wood arranged inside the fiber reinforced base material.

11. The method of manufacturing a flat lightweight component according to claim 9 or 10, characterized in that, In the woven fabric base material manufacturing step, the woven fabric base material is constituted by fiber tows that become a plurality of central yarns arranged in parallel in the same direction, and fiber tows that become binding yarns crossing the central yarns, and a fiber tow that becomes a central yarn in an end region of at least one side of the flat lightweight member is used that is smaller than a fiber tow that becomes a central yarn in a central region of the flat lightweight member.

12. The method of manufacturing a flat lightweight component according to claim 9 or 10, characterized in that, In the woven fabric base material manufacturing step, the woven fabric base material is constituted by fiber tows that become a plurality of central yarns arranged in parallel in the same direction, and fiber tows that become binding yarns crossing the central yarns, a fiber tow that becomes a central yarn in an end region of one side of the flat lightweight member is used that is smaller than a fiber tow that becomes a central yarn in a central region of the flat lightweight member, and a fiber tow that becomes a central yarn in an end region of the other side of the flat lightweight member is used that is larger than a fiber tow that becomes a central yarn in a central region of the flat lightweight member.

13. The method of manufacturing a flat lightweight component according to claim 9 or 10, wherein The fiber tows that become central yarns and the fiber tows that become binding yarns constituting the woven fabric base material are all dry fiber tows.

14. The method of manufacturing a flat lightweight component according to claim 9 or 10, wherein The fiber tows that become central yarns and the fiber tows that become binding yarns constituting the woven fabric base material are all prepregs containing a resin.

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