Molded body and method for manufacturing the same

Abstract

The present invention provides a molded article having high performance in reducing energy caused by the application of a load, which is obtained from a fiber-reinforced resin containing reinforcing fibers oriented and arranged unidirectionally. The present invention for solving the above problems relates to a molded article having a reinforcing layer formed by laminating fiber-reinforced resin layers, the fiber-reinforced resin layer containing a plurality of reinforcing fibers oriented and arranged unidirectionally and a matrix resin impregnated in the reinforcing fibers. In the molded article, the reinforcing layer has a plurality of orientation offset layers, and the orientation offset layer is a fiber-reinforced resin layer in which the angle formed by the reinforcing fibers with respect to the long axis direction of the reinforcing layer, that is, the offset angle, is 25° or more and 65° or less or -65° or more and -25° or less.

Description

Technical Field

[0001] The present invention relates to a molded body and a method for manufacturing the same. Background Art

[0002] Fiber-reinforced resins including multiple reinforcing fibers oriented and arranged in a specified direction and a resin composition (matrix resin) impregnated in the reinforcing fibers are known. Since such fiber-reinforced resins are lighter than metals and have high mechanical strength on the other hand, their use as various structural materials or reinforcing materials is being studied.

[0003] Patent Document 1 describes using a structural material as a shock-absorbing component of an automobile, the structural material being laminated in the following manner: a fiber-reinforced resin including randomly oriented reinforcing fibers and a matrix resin impregnated in the reinforcing fibers is used to sandwich a fiber-reinforced resin including reinforcing fibers oriented in two directions orthogonal to each other and arranged in a lattice pattern and a matrix resin impregnated in the reinforcing fibers.

[0004] Patent Document 1 describes that the reinforcing fibers arranged in the lattice pattern are arranged so as to be oriented at 0° (front-rear direction) and 90° (vehicle width direction) with respect to the front-rear direction of the vehicle. In addition, Patent Document 1 describes that the reinforcing fibers arranged in the lattice pattern have high strength against collision loads in the front-rear direction.

[0005] Prior Art Documents

[0006] Patent Documents

[0007] Patent Document 1: International Publication No. 2014 / 106924 Summary of the Invention

[0008] Problems to be Solved by the Invention

[0009] As also described in Patent Document 1, fiber-reinforced resins including reinforcing fibers oriented and arranged in a specified direction have high strength (high elastic modulus) against loads, and thus are useful as various structural materials, reinforcing materials, and the like.

[0010] However, for example, in the case of an automobile, in consideration of the safety of passengers, reduction of energy at the time of collision is also required. Therefore, in order to reduce the energy at the time of collision, components formed of a material such as a rubber material that easily stretches (has a large fracture strain) when a tensile load is applied are used in automobiles. However, the above-described fiber-reinforced resin is considered to have a small fracture strain and poor shock absorption performance. On the other hand, rubber materials and the like have a low elastic modulus and are not suitable for use as structural materials, reinforcing materials, and the like.

[0011] In view of the above problems, an object of the present invention is to provide a molded body having high performance in reducing energy caused by the application of a load, which is obtained from a fiber-reinforced resin containing reinforcing fibers oriented and arranged unidirectionally, and a method for manufacturing the molded body.

[0012] Means for Solving the Problem

[0013] A molded body according to one aspect of the present invention for solving the above problems has a reinforcing layer formed by laminating fiber-reinforced resin layers. The fiber-reinforced resin layer contains a plurality of reinforcing fibers oriented and arranged unidirectionally and a matrix resin impregnated in the reinforcing fibers. In the molded body, the reinforcing layer has a plurality of orientation offset layers, and the orientation offset layer is a fiber-reinforced resin layer in which the angle formed by the reinforcing fibers with respect to the long axis direction of the reinforcing layer, that is, the offset angle, is 25° or more and 65° or less, or -65° or more and -25° or less.

[0014] A film-like molded body according to another aspect of the present invention for solving the above problems is a molded body having a reinforcing layer formed by laminating fiber-reinforced resin layers. The fiber-reinforced resin layer contains a plurality of reinforcing fibers oriented and arranged unidirectionally and a matrix resin impregnated in the reinforcing fibers. In the molded body, the tensile elastic modulus of the reinforcing layer is 5.0 GPa or more and the fracture strain is 7.0%.

[0015] A method for manufacturing a molded body according to another aspect of the present invention for solving the above problems includes a step of laminating a plurality of film-like fiber-reinforced resins and fusing them to each other to form a reinforcing layer. The plurality of film-like fiber-reinforced resins have a plurality of reinforcing fibers oriented and arranged unidirectionally and a matrix resin impregnated in the reinforcing fibers. In the above manufacturing method, the plurality of film-like fiber-reinforced resins are arranged at an angle for forming a plurality of orientation offset layers and fused to form the reinforcing layer. The orientation offset layer is a fiber-reinforced resin layer in which the angle formed by the reinforcing fibers with respect to the long axis direction of the reinforcing layer, that is, the offset angle, is 25° or more and 65° or less, or -65° or more and -25° or less.

[0016] Effects of the Invention

[0017] According to the present invention, there are provided a molded body having high performance in reducing energy caused by the application of a load, which is obtained from a fiber-reinforced resin containing reinforcing fibers oriented and arranged unidirectionally, and a method for manufacturing the molded body. Detailed Embodiments

[0018] 1. Molded Body

[0019] One embodiment of the present invention relates to a molded body having a reinforcing layer formed by laminating fiber-reinforced resin layers. The fiber-reinforced resin layer includes a plurality of reinforcing fibers arranged along a unidirectional orientation and a resin composition (matrix resin) impregnated in the reinforcing fibers. The reinforcing layer is formed by laminating the fiber-reinforced resin layers, and the fiber-reinforced resin layer has a layer formed by laminating in such a manner that the angle of orientation of the reinforcing fibers is a direction offset with respect to the long axis direction of the reinforcing layer.

[0020] 1-1. Reinforcing layer

[0021] 1-1-1. Constitution of the reinforcing layer

[0022] The above-mentioned reinforcing layer is formed by laminating a plurality of the above-mentioned fiber-reinforced resin layers. The plurality of fiber-reinforced resin layers include a plurality of fiber-reinforced resin layers having different orientation directions of the reinforcing fibers, and the matrix resins of each layer are fused and integrated.

[0023] It should be noted that the fiber-reinforced resin layer is a layer including a matrix resin and a collection of a plurality of reinforcing fibers oriented in the same direction within the same layer. Therefore, a layer in which a plurality of reinforcing fibers are oriented in a certain direction and a layer in which a plurality of reinforcing fibers are oriented in different directions are different fiber-reinforced resin layers. In addition, when manufacturing a reinforcing layer by laminating a plurality of layers in such a manner that the reinforcing fibers are oriented in the same direction, if the cross section of the reinforcing layer is observed, it is observed that the reinforcing fibers in the lower layer form a collection of reinforcing fibers, and the reinforcing fibers in the upper layer form a different collection of reinforcing fibers. Thus, even if the layers formed by orienting the reinforcing fibers in the same direction are continuously arranged in the lamination direction and are formed as different layers during manufacturing, when a region where the collection of reinforcing fibers is separated (that is, a region where the matrix resin is enriched is observed between the collections of reinforcing fibers above and below) is observed in the cross section, they are considered to be different fiber-reinforced resin layers.

[0024] In addition, when it can be determined during manufacturing that a UD sheet (described later) of the same thickness is laminated and fused to form a reinforcing layer, a region having a thickness equivalent to the thickness of one UD sheet can be regarded as one fiber-reinforced resin layer.

[0025] The above-mentioned reinforcing layer can form a planar or three-dimensional molded body alone, or can be disposed on the surface of another substrate to reinforce the substrate. When the molded body has a portion where a plurality of the above-mentioned fiber-reinforced resin layers are laminated and the matrix resins are fused, the entire plurality of fiber-reinforced resin layers is the reinforcing layer.

[0026] The planar shape of the above-mentioned reinforcing layer is not particularly limited, but is a shape having a long axis direction.

[0027] The so-called major axis direction, for example, when the base material layer is rectangular, refers to the direction connecting the opposite short sides to each other. However, when the molded body is square, it can be the direction connecting any pair of opposite sides to each other. When the molded body has a shape other than these, the major axis direction is: for the rectangle with the largest area that can be contained within the molded body, the direction connecting the opposite short sides to each other.

[0028] The above-mentioned reinforcing layer includes multiple fiber-reinforced resin layers (hereinafter, also simply referred to as "orientation offset layers"). The fiber-reinforced resin layers are laminated and fused in such a way that the angle formed by the direction of the reinforcing fiber orientation with respect to the above-mentioned major axis direction (hereinafter, also simply referred to as "offset angle") is 25° or more and 65° or less.

[0029] The molded body having the above-mentioned reinforcing layer has an increased elastic modulus through multiple reinforcing fibers arranged in a unidirectional orientation. Thus, according to the insights of the inventors of the present application, the reinforcing layer having the above-mentioned orientation offset layer can absorb a large amount of the applied energy (for example, the strain energy at break in a tensile test (hereinafter, also simply referred to as "strain energy") is high). Therefore, the molded body having the above-mentioned reinforcing layer has high rigidity and excellent impact absorption performance.

[0030] On the other hand, for such a laminate with an offset angle of 0° and 90° described in Patent Document 1, the elastic modulus is high, but the strain energy is small.

[0031] The above-mentioned multiple orientation offset layers can be continuously arranged in the lamination direction, or a layer that is not an orientation offset layer (that is, a layer in which the reinforcing fibers are oriented in the major axis direction or the offset angle is not 25° or more and 65° or less) can be interposed therebetween and laminated.

[0032] In addition, the offset angles of the above-mentioned multiple orientation offset layers can be all the same, or can include multiple orientation offset layers with different offset angles.

[0033] In addition, for the above-mentioned multiple orientation offset layers, the reinforcing fibers can be offset and arranged in the same direction with respect to the major axis direction, or can include layers in which the reinforcing fibers are offset and arranged in different directions with respect to the major axis direction. That is, when the offset angle in any (for example, the orientation offset layer arranged at one end in the lamination direction) orientation offset layer is set to a positive value (25° or more and 65° or less), the reinforcing layer can also have other orientation offset layers with an offset angle less than -25° and exceeding -65°. It should be noted that hereinafter, the orientation offset layer with an offset angle of 25° or more and 65° or less will also be referred to as a "positive orientation offset layer", and the orientation offset layer with an offset angle of -25° or less and -65° or more will also be referred to as a "negative orientation offset layer".

[0034] From the viewpoint of further increasing the strain energy of the reinforcing layer, it is preferable that a plurality of orientation offset layers are continuously arranged in the stacking direction. Further, from the same viewpoint, among the plurality of orientation offset layers, it is preferable that positive orientation offset layers and negative orientation offset layers are continuously arranged in the stacking direction.

[0035] From the viewpoint of further increasing the strain energy of the reinforcing layer, when a plurality of orientation offset layers are continuously arranged in the stacking direction, it is preferable that the offset angles of two consecutive orientation offset layers are closer. Specifically, the absolute value difference of the offset angles of the two consecutive orientation offset layers is preferably 0° or more and 30° or less, more preferably 0° or more and 20° or less, still more preferably 0° or more and 10° or less, and particularly preferably 0° or more and 5° or less. It should be noted that in this specification, the absolute value difference of the offset angles means the value obtained by subtracting the offset angle of the orientation offset layer with the smaller absolute value of the offset angle from the offset angle of the orientation offset layer with the larger absolute value of the offset angle.

[0036] Further, when the reinforcing layer includes a plurality of groups of the above two consecutive orientation offset layers, it is preferable that in all groups of the orientation offset layers, the absolute value difference of the offset angles of these two consecutive orientation offset layers is 0° or more and 30° or less, more preferably 0° or more and 20° or less, still more preferably 0° or more and 10° or less, and particularly preferably 0° or more and 5° or less. In other words, it is preferable that the reinforcing layer does not have a group of two consecutive orientation offset layers in which the absolute value difference of the offset angles is not included in the above range.

[0037] Similarly, in the laminate, the absolute value difference between the absolute value of the offset angle in the offset layer and the absolute value of the angle formed by the reinforcing fibers arranged in a unidirectional orientation in the fiber-reinforced resin layer continuously arranged in the stacking direction with respect to the major axis direction of the above reinforcing layer is preferably always 0° or more and 30° or less, more preferably always 0° or more and 20° or less, still more preferably always 0° or more and 10° or less, and particularly preferably always 0° or more and 5° or less.

[0038] Further, from the viewpoint of further increasing the strain energy of the reinforcing layer, when positive orientation offset layers and negative orientation offset layers are continuously arranged in the stacking direction, the absolute value difference of the offset angles of two consecutive orientation offset layers is also preferably 0° or more and 30° or less, more preferably 0° or more and 20° or less, still more preferably 0° or more and 10° or less, and particularly preferably 0° or more and 5° or less.

[0039] Similarly, when the reinforcing layer has a plurality of positive orientation offset layers and a plurality of negative orientation offset layers, the absolute value of the difference between the average value of the offset angles of the positive orientation offset layers and the absolute value of the average value of the offset angles of the negative orientation offset layers is preferably 0° or more and 30° or less, more preferably 0° or more and 20° or less, still more preferably 0° or more and 10° or less, and particularly preferably 0° or more and 5° or less.

[0040] In addition, from the viewpoint of further increasing the strain energy of the reinforcing layer, the plurality of orientation offset layers preferably have at least one group of orientation offset layers with closer offset angles. Specifically, the plurality of orientation offset layers preferably have a group of orientation offset layers with an offset angle difference of 0° or more and 30° or less, more preferably a group of orientation offset layers with an offset angle difference of 0° or more and 20° or less, still more preferably a group of orientation offset layers with an offset angle difference of 0° or more and 10° or less, and particularly preferably a group of orientation offset layers with an offset angle difference of 0° or more and 30° or less.

[0041] In addition, from the same viewpoint, among the plurality of orientation offset layers, the absolute value of the difference between the absolute value of the offset angle in the orientation offset layer with the largest absolute value of the offset angle and the absolute value of the offset angle in the orientation offset layer with the largest absolute value of the offset angle is preferably 0° or more and 30° or less, more preferably 0° or more and 20° or less, still more preferably 0° or more and 10° or less, and particularly preferably 0° or more and 5° or less.

[0042] The reinforcing layer preferably has 3 or more and 100 or less orientation offset layers, more preferably 4 or more and 50 or less orientation offset layers. When the number of orientation offset layers is 3 or more, warping of the reinforcing layer is less likely to occur. When the number of orientation offset layers is 100 or less, it is easy to manufacture the reinforcing layer.

[0043] It should be noted that the reinforcing layer or the molded body may also have a layer that is not an orientation offset layer (hereinafter, also simply referred to as a "non-orientation offset layer"). However, from the viewpoint of further increasing the strain energy and fracture strain of the reinforcing layer, the reinforcing layer or the molded body preferably does not include a non-orientation offset layer with an offset angle of 0° or more and less than 25°. In addition, from the viewpoint of further increasing the strain energy and elastic modulus of the reinforcing layer, the reinforcing layer or the molded body preferably does not include a non-orientation offset layer greater than 65° and 90° or less. From these viewpoints, the reinforcing layer or the molded body is further preferably free of non-orientation offset layers.

[0044] In addition, the reinforcing layer may have an orientation offset layer with an offset angle of 25° or more and 65° or less. From the viewpoint of further improving the strain energy, elastic modulus, and fracture strain of the reinforcing layer, it is preferably an orientation offset layer with an offset angle of 25° or more and 50° or less, and more preferably an orientation offset layer with an offset angle of 30° or more and 45° or less.

[0045] The thickness of the reinforcing layer is preferably 0.3 mm or more and 10 mm or less, and more preferably 0.4 mm or more and 5 mm or less. When the thickness is 0.3 mm or more, the strain energy can be made larger, and the workability of the molded body including only the reinforcing layer is improved. When the thickness is 10 mm or less, the followability to the surface shape (e.g., curved surface, step, etc.) of the substrate on which the reinforcing layer is disposed is improved.

[0046] The area of the surface of the reinforcing layer parallel to the plane of the reinforcing fiber orientation is preferably 0.01 m 2 or more, and more preferably 0.05 m 2 or more, and further preferably 0.1 m 2 or more. When the area of the largest surface is the above value or more, even when fixed with fasteners or the like, there is sufficient area, and thus there is a tendency to more easily exhibit the effect of improving the strain energy. The area of the largest surface can be, for example, 100 m 2 or less. It should be noted that when the molded body includes only the reinforcing layer and the surface areas of the front and back are different, it is preferable that the area of the smaller surface of the front and back is within the above range.

[0047] The minimum width of the reinforcing layer (the width in the direction orthogonal to the long axis direction in the plane of the reinforcing fiber orientation) is preferably 5 mm or more, more preferably 10 mm or more, and further preferably 20 mm or more. When the minimum width is the above value or more, there is a tendency that even in the presence of defects such as minute defects that may occur in actual manufacturing, the effect of improving the strain energy is more easily exhibited. The minimum width of the reinforcing layer can be, for example, 10 m or less.

[0048] The reinforcing layer is formed by laminating fiber-reinforced resin layers each containing a plurality of reinforcing fibers oriented and arranged in one direction and a matrix resin impregnated in the reinforcing fibers. In addition, the fiber-reinforced resin layer includes the above-mentioned orientation offset layer. Typically, the above-mentioned matrix resins are integrally fused between layers.

[0049] The reinforcing layer configured as such has a high tensile elastic modulus and a large fracture strain. Therefore, the reinforcing layer is not easily deformed, but when a high stress is applied to deform it, the elongation rate until fracture is also large. Therefore, the strain energy of the reinforcing layer is large. Specifically, the above-mentioned reinforcing layer can achieve a tensile elastic modulus of 5.0 GPa or more and a fracture strain of 7.0% or more. The tensile elastic modulus of the reinforcing layer is preferably 5.0 GPa or more, more preferably 10.0 GPa or more. The upper limit of the tensile elastic modulus of the reinforcing layer is not particularly limited and can be 100.0 GPa or less. The fracture strain of the reinforcing layer is preferably 5.0% or more, more preferably 8.0% or more. The upper limit of the fracture strain of the reinforcing layer is not particularly limited and can be 300.0% or less.

[0050] Similarly, the tensile fracture strength of the above-mentioned reinforcing layer is preferably 20.0 MPa or more, more preferably 100.0 MPa or more. The upper limit of the tensile fracture strength of the reinforcing layer is not particularly limited and can be 2000.0 MPa or less. In addition, the strain energy per unit volume of the above-mentioned reinforcing layer is preferably 1 N·mm / mm 3 or more, more preferably 2.00 N·mm / mm 3 or more. The upper limit of the strain energy per unit volume of the reinforcing layer is not particularly limited and can be 10.00 N·mm / mm 3 or less.

[0051] The tensile elastic modulus and fracture strain of the above-mentioned reinforcing layer can be set to the following values: For a reinforcing layer cut into a tensile test piece shape of 250 mm in length × 15 mm in width, using a tensile testing machine (for example, AG-X100 kN manufactured by Shimadzu Corporation), a tensile test is performed at 23°C at a tensile speed of 1.5 mm / minute, and based on the stress-strain curve obtained from the results of this tensile test, the values are obtained in accordance with ISO 527-5 (2009).

[0052] 1-1-2. Reinforcing fiber

[0053] The material of the above-mentioned reinforcing fiber is not particularly limited. For example, carbon fiber, glass fiber, aramid fiber, alumina fiber, silicon carbide fiber, boron fiber, and metal fiber can be used as the above-mentioned reinforcing fiber. Among these, carbon fiber and glass fiber are preferred.

[0054] From the viewpoint of sufficiently improving the strength improvement effect brought by the reinforcing fiber, the average diameter of the above-mentioned reinforcing fiber is preferably 1 μm or more and 20 μm or less, more preferably 4 μm or more and 10 μm or less.

[0055] The length of the above-mentioned reinforcing fiber is usually 15 mm or more. The lower limit value of the length of the above-mentioned reinforcing fiber is preferably 20 mm or more, more preferably 100 mm or more, and further preferably 500 mm or more. The maximum value of the upper limit of the length of the above-mentioned reinforcing fiber is, for example, 50 m. Usually, the UD sheet used in the manufacturing method of the molded body described later is a sheet obtained by cutting the UD sheet into a desired length after manufacturing the UD sheet. Therefore, the length of the reinforcing fiber contained in the UD sheet included in the molded body may be less than the minimum value of the above length.

[0056] In addition, the above-mentioned reinforcing fiber can be sized with a sizing agent.

[0057] The above-mentioned sizing agent is not particularly limited, and a modified polyolefin is preferred. In particular, a modified polyolefin containing a metal carboxylate is more preferred. The above-mentioned modified polyolefin is, for example, a substance obtained by graft-introducing a carboxyl group, a carboxylic anhydride group, or a carboxylic ester group onto the polymer chain of an unmodified polyolefin and forming a salt between the above functional group and a metal cation.

[0058] The above-mentioned unmodified polyolefin is preferably an ethylene-based polymer having a content of structural units derived from ethylene of 50 mol% or more, or a propylene-based polymer having a content of structural units derived from propylene of 50 mol% or more. Examples of the above-mentioned ethylene-based polymer include ethylene homopolymers and copolymers of ethylene and an α-olefin having 3 to 10 carbon atoms. Examples of the above-mentioned propylene-based polymer include propylene homopolymers and copolymers of propylene and ethylene or an α-olefin having 4 to 10 carbon atoms. The above-mentioned unmodified polyolefin is preferably homopolypropylene, homopolyethylene, ethylene-propylene copolymer, propylene-1-butene copolymer, or ethylene-propylene-1-butene copolymer.

[0059] In addition, the above-mentioned reinforcing fiber can be bundled to form a fiber bundle. At this time, the number of single filaments in each bundled carbon fiber bundle is preferably 100 or more and 100,000 or less, and more preferably 1,000 or more and 50,000 or less.

[0060] The content of the above-mentioned reinforcing fiber relative to the total mass of the reinforcing layer is preferably 20% by mass or more and 80% by mass or less, more preferably 30% by mass or more and 75% by mass or less, further preferably 30% by mass or more and 65% by mass or less, and particularly preferably 35% by mass or more and 60% by mass or less.

[0061] The content of the above-mentioned reinforcing fiber relative to the total volume of the reinforcing layer is preferably 10% by volume or more and 70% by volume or less, more preferably 15% by volume or more and 60% by volume or less, and further preferably 20% by volume or more and 60% by volume or less.

[0062] 1-1-3. Matrix resin

[0063] The material of the above-mentioned matrix resin is not particularly limited, and the above-mentioned matrix resin can be a thermoplastic resin or a thermosetting resin. In addition, the above-mentioned matrix resin can be a crystalline resin or an amorphous resin.

[0064] Examples of the above-mentioned thermoplastic resins include: polyolefin resins such as polyethylene, polypropylene, polybutene, and poly(4-methyl-1-pentene), polyamide resins, polyester resins, polystyrene resins, thermoplastic polyimide resins, polyamide-imide resins, polycarbonate resins, polyphenylene ether resins, polyphenylene sulfide resins, polyacetal resins, acrylic resins, polyetherimide resins, polysulfone resins, polyether ketone resins, polyether ether ketone resins, polyarylate resins, polyether nitrile resins, vinyl chloride resins, ABS resins, and fluororesins, etc.

[0065] Examples of the above-mentioned thermosetting resins include epoxy resins, phenolic resins, melamine resins, urea resins, diallyl phthalate resins, silicone resins, polyurethane resins, furan resins, ketone resins, xylene resins, thermosetting polyimide resins, unsaturated polyester resins, and diallyl terephthalate resins, etc.

[0066] Among these, from the viewpoint of further improving the strain energy of the reinforcing layer, thermoplastic resins are preferred. In addition, from the same viewpoint, among thermoplastic resins, polyamide resins and polyolefin resins are preferred.

[0067] The above-mentioned matrix resin can be a resin composition containing additives. Examples of the above-mentioned additives include known filler materials (inorganic filler materials, organic filler materials), pigments, dyes, weather resistance stabilizers, heat stabilizers, antistatic agents, anti-slip agents, antioxidants, mildew-proof agents, antibacterial agents, flame retardants, and softeners, etc. For example, when the UD sheet is fused by laser irradiation to form a reinforcing layer, the above-mentioned matrix resin is preferably a resin composition containing a pigment that absorbs the laser of the irradiated wavelength. The above-mentioned pigment can be a pigment that absorbs light of any wavelength in the range of 300 nm or more and 3000 nm or less, and carbon black is preferred.

[0068] In addition, the matrix resin can contain other components such as resins other than the above and short fibers shorter than the above-mentioned reinforcing fibers.

[0069] The content of the above-mentioned matrix resin relative to the total mass of the reinforcing layer is preferably 20% by mass or more and 80% by mass or less, more preferably 25% by mass or more and 70% by mass or less, further preferably 35% by mass or more and 70% by mass or less, and particularly preferably 40% by mass or more and 65% by mass or less.

[0070] 1-2. Shape and Structure of the Formed Body

[0071] Regarding the above-mentioned reinforcing layer, the molded body may be composed only of the reinforcing layer, or may be disposed on the surface of another substrate to form a molded body including the substrate and the reinforcing layer. In any case, from the viewpoint of making the fiber directions of the respective layers uniform, the reinforcing layer is preferably a planar molded body or a layer formed in a two-dimensional shape on the surface of another substrate.

[0072] When the molded body is composed only of the reinforcing layer, the shape of the molded body may be planar or curved. In addition, at this time, the shape of the molded body may be a three-dimensional shape.

[0073] The above-mentioned substrate may be a substrate formed of any material among resin, metal, and ceramic. In addition, the shape of the substrate may be planar or curved, or may be a three-dimensional shape such as a hat-shaped cross section, an I-shaped cross section, or a U-shaped cross section.

[0074] The reinforcing layer may be adhered to the surface of the substrate by an adhesive or the like. When the substrate contains resin, the resin constituting the substrate and the matrix resin contained in the reinforcing layer may be joined by fusion. At this time, the resin constituting the substrate is preferably the same type of resin as the matrix resin of the reinforcing layer. It should be noted that the so-called same type of resin means that the bonding structure (for example, ester structure and amide bond, etc.) that bonds the respective structural units derived from the monomers in the main chain of the resin is the same, or is bonded through the same polymerizable group (for example, vinyl, etc.). The above-mentioned same type of resin preferably has structural units derived from the same monomer (for example, ethylene, propylene).

[0075] The shape of the substrate is not particularly limited. For example, the substrate may have a long-axis shape extending in one direction. At this time, it is preferable that the long-axis direction of the above-mentioned substrate is substantially the same as the long-axis direction of the above-mentioned reinforcing layer. Regarding the above-mentioned reinforcing layer, the substrate provided with the reinforcing layer has high strength in the long-axis direction of the reinforcing layer and can efficiently reduce the energy caused by applying a load in the long-axis direction of the reinforcing layer. Therefore, by making the long-axis direction of the substrate substantially the same as the long-axis direction of the reinforcing layer, it can be suitably used as a structural material or a reinforcing material for applications where a load is expected to be applied in these long-axis directions.

[0076] It should be noted that in this specification, the so-called substantially the same not only means that the angular difference between the two directions is 0°, but also includes the case where there is a slight difference in the angles of the two directions. Specifically, in this specification, substantially the same means that the angular difference between the two directions is 0° or more and 10° or less, preferably 0° or more and 5° or less.

[0077] 2. Manufacturing method of the molded body

[0078] The manufacturing method of the molded body is not particularly limited. For example, the molded body can be manufactured by the following methods: pasting a prefabricated reinforcing layer on the surface of a substrate; or fusing a film-like fiber-reinforced resin (also simply referred to as "UD sheet") having a plurality of reinforcing fibers arranged in a unidirectional orientation and impregnated with a matrix resin in the reinforcing fibers with the surface of the substrate by hot pressing or laser irradiation; or integrating the reinforcing layer with the substrate by insert molding. At this time, without using a substrate, the UD sheets are fused only with each other by hot pressing or laser irradiation, and thus a molded body composed only of the reinforcing layer can also be obtained.

[0079] When using a UD sheet to form a reinforcing layer, the UD sheets are angled and laminated such that the offset angles of the respective orientation offset layers are within the above range, or UD sheets with different orientation directions of the reinforcing fibers are laminated, and the UD sheets are fused by hot pressing or laser irradiation.

[0080] Alternatively, for a UD sheet that has been disposed on a substrate or fused with a lower fiber-reinforced resin layer, the following steps can be repeated: a UD sheet for forming the next fiber-reinforced resin layer is disposed such that the offset angle is within the above range, and a new fiber-reinforced resin layer (orientation offset layer) is formed by hot pressing or laser irradiation.

[0081] The content of the above-mentioned reinforcing fibers relative to the total mass of the UD sheet is preferably 20% by mass or more and 80% by mass or less, more preferably 30% by mass or more and 75% by mass or less, still more preferably 30% by mass or more and 65% by mass or less, and particularly preferably 35% by mass or more and 60% by mass or less. In addition, the content of the above-mentioned matrix resin relative to the total mass of the UD sheet is preferably 20% by mass or more and 80% by mass or less, more preferably 25% by mass or more and 70% by mass or less, still more preferably 35% by mass or more and 70% by mass or less, and particularly preferably 40% by mass or more and 65% by mass or less.

[0082] The content of the above-mentioned reinforcing fibers (fiber volume fraction: Vf) relative to the total volume of the UD sheet is preferably 10% by volume or more and 70% by volume or less, more preferably 15% by volume or more and 60% by volume or less, still more preferably 20% by volume or more and 60% by volume or less.

[0083] The thickness of the UD sheet is not particularly limited, and is preferably 1 μm or more and 500 μm or less, more preferably 5 μm or more and 400 μm or less, still more preferably 5 μm or more and 300 μm or less.

[0084] The manner of using the UD sheet is not particularly limited either. The UD sheet can be used directly alone, or can be appropriately cut into strips and then used.

[0085] It should be noted that the reinforcing fibers can also be assembled in such a way that the offset angle of the orientation offset layer is within the above range, and then the matrix resin is impregnated into the reinforcing fibers to produce a reinforcing layer.

[0086] 3. Use

[0087] The use of the above molded body is not limited, and it is useful as a reinforcing material for other structural materials, especially as a reinforcing material for components constituting vehicles and aircraft that generate instantaneous impacts.

[0088] Specific examples of the uses of the above-mentioned molded bodies include: components and members of general flying bodies such as aircraft and helicopters, which include primary structural materials such as main wings, vertical and horizontal tail fins, secondary structural materials such as ailerons, rudders, and elevators, interior decoration materials such as seats and platforms, power plants, hydraulic cylinders, and composite brakes, etc.; rocket components and members, which include nozzle cones and engine cases, etc.; artificial satellite components and members, which include antennas, structures, solar panels, battery boxes, and telescopes, etc.; mechanical components and members, which include frames, shafts, rollers, leaf springs, machine tool heads, robotic arms, handling hands, and synthetic fiber tanks, etc.; high-speed rotating body components, which include centrifuge rotors and uranium enrichment cylinders, etc.; electronic and electrical components and members, which include parabolic antennas, battery components, radars, acoustic speaker cones, computer components, printer components, personal computer casings, and tablet computer casings, etc.; automotive and motorcycle components and members, which include frame members, semi-structural members, outer panel members, interior and exterior trim members, power plants, other equipment - hydraulic cylinders, brakes, battery boxes, drive shafts, engine parts, spoilers, racing car bodies, crash cones, chairs, tablet computers, phone covers, undercover, side covers, transmission covers, battery trays, rear pedals, spare tire compartments, bus body walls, and truck body walls, etc.; vehicle components and members, which include interior decoration materials, floor panels, roof panels, linear motor car bodies, Shinkansen and railway car bodies, windshield wipers, bogies, and seats, etc.; ship components and members - hulls, which include ship hulls such as yachts, cruisers, and boats, masts, rudders, propellers, hard sails, screws, military hulls, submarine hulls, and deep-sea exploration ships, etc.; pressure vessel components and members, which include actuators, cylinders, gas cylinders, hydrogen tanks, CNG tanks, and oxygen tanks, etc.; scientific device components and members, which include stirring blades, pipes, tanks, bottom pipes, and equipment piping, etc.; wind power generation components and members, which include blades, skins, frame structures, and de-icing systems, etc.; medical and nursing equipment components and members - supplies, which include X-ray diagnostic device components, wheelchairs, artificial bones, prosthetic feet and hands, walking sticks, nursing aids - robots (power assist tools), walkers, and nursing beds, etc.; civil engineering and infrastructure components and members, which include CF composite cables, concrete reinforcement components, guardrails, bridges, tunnel walls, protective covers, cables, tension rods, strand rods, and flexible pipes, etc.;Components and members for undersea oilfield excavation, including marine risers, flexible casings, flexible risers, and drilling risers, etc.; sports and leisure goods, including fishing rods, reels, golf clubs, tennis rackets, badminton rackets, snowboards, ski poles, snow skis, ice hockey sticks, snowmobiles, archery equipment, bamboo swords for kendo, baseball bats, swimming platforms, sports equipment for disabled people, and sports helmets, etc.; bicycle components, including frames, disc wheels, rims, handlebars, and saddles, etc.; daily necessities, including glasses, leather bags, Western-style umbrellas, and ballpoint pens, etc.; and components, members, and goods for other industrial uses, including plastic pallets, containers, logistics materials, resin molds, furniture, Western-style umbrellas, helmets, pipes, scaffolding boards, safety shoes, protection devices, fuel cell covers, drone blades, frames, jigs, and jig frames, etc.; and so on.

[0089] Examples

[0090] Hereinafter, the present invention will be described more specifically with reference to examples, but the scope of the present invention is not limited to the description of the examples.

[0091] 1. Production of the molded body

[0092] As the UD sheet, a UD sheet (manufactured by Mitsui Chemicals, Inc., TAFNEX (registered trademark), fiber volume fraction (VF): 50%, thickness 0.16 mm) obtained by impregnating polypropylene in carbon fibers arranged in a unidirectional manner was prepared. The UD sheet was cut into a size of 300 mm in length × 200 mm in width, and the orientation direction of the carbon fibers was 30° with respect to the longitudinal direction to produce a sheet for fusion.

[0093] Seven sheets of the fusion sheet were overlapped and arranged on the surface of a polyimide release film (bottom film), and a polyimide release film (top film) was further arranged thereon. The seven sheets of the fusion sheet were arranged such that the orientation direction of the carbon fibers was alternately 30° and -30° with respect to a direction defined along the surface of the bottom film.

[0094] The laminate formed by overlapping the above bottom film, seven sheets of the fusion sheet, and the top film was placed in a pressing device (manufactured by Toyo Seiki Seisaku-sho, Ltd., Mini Test Press), the temperature during pressing was 180 °C, a pressure of 2 MPa was applied while maintaining for 3 minutes, and then the pressure was released. Immediately after that, the above hot-pressed laminate was placed in a cooling pressing device through which cooling water at 30 °C was flowing, a pressure of 2 MPa was applied while maintaining for 3 minutes, and then the pressure was released. Then, the laminate was taken out from the cooling pressing device, the release film was removed, and a molded body 1 composed only of a reinforcing layer was obtained, the reinforcing layer being formed by laminating seven layers of fiber-reinforced resin layers.

[0095] Seven sheet materials for fusion were arranged on the release film, and the sheet materials for fusion were produced and hot-pressed in such a manner that the angle formed by the orientation direction of the carbon fibers with respect to a direction defined along the surface of the bottom film was the angle shown in Table 1, thereby obtaining molded bodies 2 to 8. It should be noted that when producing the molded body 4, a UD sheet material (fiber volume fraction (VF): 50%, thickness 0.16 mm) obtained by impregnating polyamide 12 (manufactured by Ube Industries, Ltd., UBESTA3014U) in carbon fibers arranged in a unidirectional manner was prepared.

[0096] Table 1 shows the types of matrix resins in the fiber-reinforced resin layers of each of the molded bodies 1 to 8 and the angles formed by the orientation directions of the carbon fibers with respect to the above-mentioned one direction. It should be noted that the first layer is the layer arranged on the side of the bottommost film, and the seventh layer is the layer arranged on the side of the bottommost film.

[0097] [Table 1]

[0098]

[0099] 2. Evaluation of Molded Bodies

[0100] For the molded bodies 1 to 8, a direction defined along the surface of the bottom film was taken as the longitudinal direction, and tensile test pieces with a shape of 250 mm in length × 15 mm in width were cut. For the cut pieces cut from each molded body, tabs made of glass fiber-reinforced resin (GFRP) (manufactured by Nikka Kasei Co., Ltd., NIKOLYTE NL-EG, 56 mm × 15 mm × 1.5 mm) were adhered to both longitudinal ends using an adhesive (manufactured by Toagosei Co., Ltd., aronalpha extra 4020) to obtain tensile test pieces.

[0101] Each tensile test piece was set on a tensile testing machine (manufactured by Shimadzu Corporation, AG-X 100 kN), and a tensile test was conducted at 23°C at a tensile speed of 1.5 mm / minute. In accordance with ISO 527-5 (2009), the tensile elastic modulus, tensile fracture strength, and fracture strain were obtained from the stress-strain curve graph obtained. In addition, the integral value of the stress up to fracture in the stress-strain curve graph was taken as the strain energy, and the obtained strain energy was divided by the volume of the tensile test piece to obtain the strain energy per unit volume.

[0102] Table 2 shows the evaluation results of the molded bodies 1 to 8.

[0103] [Table 2]

[0104]

[0105] As can be seen from Table 2, it is observed that the closer the angle formed by the orientation direction of the carbon fiber relative to the long axis (longitudinal) direction of the molded body is to 0°, the higher the tensile elastic modulus and the tensile fracture strength tend to be. On the other hand, the fracture strain becomes smaller (Molded Body 5, Molded Body 8, etc.). In addition, when the orientation direction of the carbon fiber is 0° and 90°, the same shape is also observed (Molded Body 7).

[0106] It is observed that if the orientation direction of the carbon fiber is close to 90°, the fracture strain tends to increase. On the other hand, the tensile elastic modulus decreases and the strain energy also decreases extremely (Molded Body 6).

[0107] In contrast, if the orientation direction of the carbon fiber is 25° or more and 65° or less, a molded body with a high elastic modulus, a large fracture strain, and a high strain energy can be obtained (Molded Bodies 1 to 4).

[0108] This application is a claim for priority based on Japanese Application No. 2020-156417 filed on September 17, 2020, and the contents described in the specification, claims, and drawings of this application are incorporated herein by reference.

[0109] Industrial Applicability

[0110] The molded body of the present invention has high elasticity and high performance in reducing the energy brought about by the application of load. Therefore, the molded body of the present invention can be suitably used as various structural materials and reinforcing materials.

Claims

1. A molded body having a reinforcing layer formed by laminating a plurality of fiber-reinforced resin layers, wherein each of the fiber-reinforced resin layers includes a plurality of reinforcing fibers oriented and arranged in a single direction and a matrix resin impregnated in the reinforcing fibers. The reinforcing layer has a plurality of orientation offset layers, and each of the orientation offset layers is a fiber-reinforced resin layer in which the angle formed by the reinforcing fibers with respect to the major axis direction of the reinforcing layer, i.e., the offset angle, is 25° or more and 65° or less, or -65° or more and -25° or less. The reinforcing layer does not have a non-orientation offset layer, and the non-orientation offset layer includes a plurality of reinforcing fibers oriented and arranged at an angle greater than -25° and less than 25° with respect to the major axis direction of the reinforcing layer and a matrix resin impregnated in the reinforcing fibers and fused with the matrix resin of the orientation offset layer. The reinforcing layer does not have the following non-orientation offset layer, which includes a plurality of reinforcing fibers oriented and arranged at an angle greater than 65° and 90° or less, or -90° or more and less than -65° with respect to the major axis direction of the reinforcing layer, and a matrix resin impregnated in the reinforcing fibers and fused with the matrix resin of the orientation offset layer. Each of the plurality of fiber-reinforced resin layers is formed of a film-shaped fiber-reinforced resin having the same thickness, and the film-shaped fiber-reinforced resin includes a plurality of reinforcing fibers oriented and arranged in a single direction and a matrix resin impregnated in the reinforcing fibers.

2. The molded body according to claim 1, wherein, the plurality of orientation offset layers have: a positive orientation offset layer with the offset angle of 25° or more and 65° or less; and a negative orientation offset layer with the offset angle of -65° or more and -25° or less.

3. The molded body according to claim 1 or 2, wherein, the plurality of orientation offset layers have a set of orientation offset layers continuously arranged in the lamination direction.

4. The molded body according to claim 3, wherein, for the set of continuously arranged orientation offset layers, in all sets of the orientation offset layers, the absolute value difference of the offset angles is 10° or less.

5. The molded body according to claim 4, wherein, the set of continuously arranged orientation offset layers includes: a positive orientation offset layer with the offset angle of 25° or more and 65° or less; and a negative orientation offset layer with the offset angle of -65° or more and -25° or less.

6. The molded body according to claim 1 or 2, wherein, the absolute value difference of the offset angles between the orientation offset layer with the largest absolute value of the offset angle and the orientation offset layer with the smallest absolute value of the offset angle in the reinforcing layer is 10° or less.

7. The molded body according to claim 1 or 2, wherein, the absolute value of the offset angle in the orientation offset layer and the absolute value of the angle formed by the reinforcing fibers in a fiber-reinforced resin layer including a plurality of reinforcing fibers and a matrix resin impregnated in the reinforcing fibers and fused with the matrix resin of the orientation offset layer with respect to the major axis direction of the reinforcing layer always have an absolute value difference of 10° or less.

8. The molded body according to claim 1 or 2, wherein, The base resin is a thermoplastic resin and contains a pigment that absorbs light with any wavelength from 300 nm to 3000 nm.

9. The molded article according to claim 1 or 2, wherein, the reinforcing fiber is carbon fiber or glass fiber.

10. The molded article according to claim 1 or 2, wherein, the tensile elastic modulus of the reinforcing layer is 5.0 GPa or more and the fracture strain is 7.0%.

11. The molded article according to claim 1 or 2, which has the reinforcing layer and a substrate having the reinforcing layer on the surface.

12. The molded article according to claim 11, wherein, the substrate has an elongated shape, and the angle difference between the major axis direction of the substrate and the major axis direction of the reinforcing layer is 0° or more and 10° or less.

13. The molded article according to claim 1 or 2, which only contains the reinforcing layer.

14. A method for manufacturing a molded article, which includes a step of laminating a plurality of film-shaped fiber-reinforced resins having the same thickness and fusing them to each other to form a reinforcing layer. The plurality of film-shaped fiber-reinforced resins have a plurality of reinforcing fibers arranged along a unidirectional orientation and a base resin impregnated in the reinforcing fibers. The plurality of film-shaped fiber-reinforced resins are arranged at an angle to form a multi-layer fiber-reinforced resin layer and fused without arranging a non-oriented offset layer to form the reinforcing layer. The fiber-reinforced resin layer, i.e., the orientation offset layer, is a fiber-reinforced resin layer in which the angle formed by the reinforcing fiber with respect to the major axis direction of the reinforcing layer, i.e., the offset angle, is 25° or more and 65° or less or -65° or more and -25° or less. The non-oriented offset layer is a fiber-reinforced resin layer in which the offset angle is greater than -25° and less than 25°, and a fiber-reinforced resin layer in which the offset angle is greater than 65° and 90° or less or -90° or more and less than -65°.

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