Molded body of fiber-reinforced resin and method for producing same

Abstract

Provided is a molded body of a fiber-reinforced resin with which it is possible to form, on the surface of a UD sheet, ribs of a predetermined height made of a fiber-reinforced resin without injecting the fiber-reinforced resin. The present invention pertains to a molded body of a fiber-reinforced resin, the molded body comprising: a first fiber-reinforced resin layer containing a plurality of reinforcing fibers aligned in one direction and a matrix resin; a second fiber-reinforced resin layer in which a block containing a matrix resin and a plurality of reinforcing fibers arranged in a unidirectional orientation is disposed; and ribs that protrude from the surface of the first fiber-reinforced resin layer toward the opposite side from the second fiber-reinforced resin layer, and that contain a plurality of reinforcing fibers and a matrix resin.

Description

Technical Field

[0001] The present invention relates to a fiber-reinforced resin molded body and a method for producing the same. Background Art

[0002] Film-shaped fiber-reinforced resins (hereinafter referred to as "Uni-Direction (UD) sheets") comprising a plurality of unidirectionally oriented reinforcing fibers and a resin composition (matrix resin) impregnated into the reinforcing fibers are known. Due to their high strength, these UD sheets are used as various reinforcing materials.

[0003] In addition, as a method for improving the intensity of the molded body formed by molding the resin composition, a protrusion (rib) is sometimes provided in the molded body. Also, by providing a rib in the molded body obtained by molding the UD sheet, it is expected that the intensity of the molded body of the UD sheet will be further improved. However, although the intensity of the UD sheet is high, there is a problem that the formability (forming property) based on stamping, compression molding, etc. is relatively low. Therefore, it is difficult to form a highly rib by the molding of the UD sheet.

[0004] In order to solve this problem, Patent Document 1 describes a method for manufacturing a molded body with ribs, which molds a UD sheet (or a sheet formed by cutting a UD sheet) inside a mold having a cavity (the cavity is a shape having a space corresponding to the ribs), slightly deforms the UD sheet toward the ribs, and fills (injects) other resin materials into the remaining space of the ribs. Patent Document 1 states that, using this method, the lower side of the ribs is molded integrally with the UD sheet, so the bonding strength of the ribs is high. On the other hand, the height of the ribs can also be ensured by the injected resin material. It should be noted that, in Patent Document 1, the UD sheet formed by opening an incision in the reinforcing fibers, or the product obtained by cutting the UD sheet into small pieces is arranged in a random shape. In Patent Document 1, by arranging the reinforcing fibers that have been chopped in the above manner on the rib side of the UD sheet, it is easy for the reinforcing fibers to flow into the lower side of the ribs, thereby improving the bonding strength of the ribs.

[0005] Patent Document 2 also describes a method for producing a ribbed molded body. The method involves placing a UD sheet inside a mold and injecting a thermoplastic resin composition from the side opposite the side where the ribs will be formed. The injection pressure then causes the thermoplastic resin composition to fill the rib-side cavity between the reinforcing fibers of the UD sheet. Patent Document 2 describes how the flow pressure of the resin composition during rib formation causes the UD sheet to bend, forming a shape that adheres to the upright walls of the ribs. Patent Document 2 also describes experimental results using a thermoplastic resin composition containing glass fibers to form ribs.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Laid-Open No. 2017-80930

[0009] Patent Document 2: Japanese Patent Application Laid-Open No. 2013-169647 Summary of the Invention

[0010] Problems to be solved by the invention

[0011] As described in Patent Documents 1 and 2, when attempting to obtain a molded body having ribs using a UD sheet having low formability and difficult to mold ribs, additional resin is usually injected to form the ribs.

[0012] However, since the ribs are provided to increase the strength of the molded body, the ribs themselves are naturally required to have high strength. Furthermore, in order to increase the strength of the ribs, it is desirable to use fiber-reinforced resins for the ribs. However, according to the inventors of this application, even with the use of fiber-reinforced resins, the strength of ribs formed by injection molding, as described in Patent Documents 1 and 2, is not increased to the expected level. Further research on this point revealed that if attempts are made to form ribs by injection molding, the reinforcing fibers will be cut due to pressure during flow and injection within the injection molding machine, shortening the length of the reinforcing fibers in the ribs and making it difficult to increase the strength of the ribs.

[0013] In contrast, if the ribs are formed by press molding rather than injection molding, the fiber-reinforced resin has difficulty entering the cavity used to form the ribs, preventing the ribs from reaching the desired height. This tendency is particularly pronounced when using fiber-reinforced resin containing long reinforcing fibers to increase rib strength.

[0014] The present invention has been made in view of the above-mentioned problems of the prior art and aims to provide a fiber-reinforced resin molded body capable of forming fiber-reinforced resin ribs of a predetermined height on the surface of a UD sheet without injecting the fiber-reinforced resin, and a method for producing the same.

[0015] Means for solving problems

[0016] One embodiment of the present invention for solving the above-mentioned problems relates to the following fiber-reinforced resin molded products [1] to

[10] .

[0017] [1] A fiber-reinforced resin molded article having:

[0018] a first fiber-reinforced resin layer comprising a plurality of reinforcing fibers arranged in a unidirectional orientation and a matrix resin;

[0019] a second fiber-reinforced resin layer comprising randomly arranged blocks of a plurality of reinforcing fibers oriented in one direction and a matrix resin; and

[0020] The rib protrudes from the surface of the first fiber-reinforced resin layer toward the side opposite to the second fiber-reinforced resin layer and includes a plurality of reinforcing fibers and a matrix resin.

[0021] [2] The fiber-reinforced resin molded article according to [1], wherein the first fiber-reinforced resin layer, the second fiber-reinforced resin layer, and the rib are integrally molded.

[0022] [3] The fiber-reinforced resin molded article according to [1] or [2], wherein the first fiber-reinforced resin layer has a displaced portion where the orientation of the plurality of arranged reinforcing fibers is displaced at a location where the rib is formed.

[0023] [4] The fiber-reinforced resin molded article according to any one of [1] to [3], wherein the average fiber length of the reinforcing fibers contained in the second fiber-reinforced resin layer is substantially the same as the average fiber length of the reinforcing fibers contained in the rib.

[0024] [5] The fiber-reinforced resin molded article according to any one of [1] to [4], wherein a portion of the reinforcing fibers included in the rib portion exists across the rib portion and the first fiber-reinforced resin layer.

[0025] [6] The fiber-reinforced resin molded article according to any one of [1] to [5], wherein the height of the rib is 5 mm or more.

[0026] [7] The fiber-reinforced resin molded article according to any one of [1] to [6], wherein the thickness of the first fiber-reinforced resin layer is 40 μm to 3000 μm.

[0027] [8] The fiber-reinforced resin molded article according to any one of [1] to [7], wherein the thickness of the second fiber-reinforced resin layer is 300 μm to 4000 μm.

[0028] [9] The fiber-reinforced resin molded article according to any one of [1] to [8], wherein the first fiber-reinforced resin layer, the second fiber-reinforced resin layer, and the ribs all contain a polyolefin resin as the matrix resin.

[0029]

[10] The fiber-reinforced resin molded article according to any one of [1] to [9], wherein the average fiber length of the reinforcing fibers contained in the second fiber-reinforced resin layer is 1 mm to 40 mm.

[0030] Another embodiment of the present invention for solving the above-mentioned problems relates to the following methods

[11] to

[14] for producing a fiber-reinforced resin molded body.

[0031]

[11] A method for producing a fiber-reinforced resin molded article, comprising:

[0032] The step of arranging a first fiber-reinforced resin and a plurality of second fiber-reinforced resins in a laminated manner inside a mold, wherein the first fiber-reinforced resin comprises a plurality of reinforcing fibers arranged in a unidirectional orientation and a matrix resin, and the plurality of second fiber-reinforced resins are randomly assembled blocks each comprising a plurality of reinforcing fibers arranged in a unidirectional orientation and a matrix resin and having a smaller size than the first fiber-reinforced resin; and

[0033] The process of molding the first fiber-reinforced resin and the plurality of second fiber-reinforced resins arranged above inside the mold,

[0034] The mold has a cavity for molding the molded body having ribs through the molding step.

[0035] In the arranging step, the first fiber-reinforced resin is arranged on the cavity side relative to the second fiber-reinforced resin.

[0036]

[12] The method for producing a molded body of a fiber-reinforced resin as described in

[11] , wherein, in the aforementioned arrangement step, the aforementioned plurality of second fiber-reinforced resins are arranged so that the mass per unit area of ​​the aforementioned reinforcing fibers possessed by the aforementioned plurality of second fiber-reinforced resins becomes 270 g / m 2 Above 3600g / m 2 The following configuration is made inside the mold.

[0037]

[13] The method for manufacturing a fiber-reinforced resin molded body as described in

[11] or

[12] , wherein, in the aforementioned arrangement step, the aforementioned first fiber-reinforced resin having a thickness of not less than 0.01 mm and not more than 0.5 mm is arranged inside the aforementioned mold.

[0038]

[14] A method for manufacturing a molded body of a fiber-reinforced resin as described in any one of

[11] to

[13] , wherein, in the aforementioned arrangement step, the aforementioned plurality of second fiber-reinforced resins having an average fiber length of the aforementioned reinforcing fibers of not less than 1 mm and not more than 40 mm are arranged inside the aforementioned mold.

[0039] Effects of the Invention

[0040] According to the present invention, a fiber-reinforced resin molded article capable of forming fiber-reinforced resin ribs of a predetermined height on the surface of a UD sheet without injecting the fiber-reinforced resin is provided, as well as a method for producing the same. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] [ Figure 1 ] Figure 1 This is a perspective view showing an exemplary structure of a fiber-reinforced resin molded article according to one embodiment of the present invention.

[0042] [ Figure 2 ] Figure 2 A is along Figure 1 A schematic cross-sectional view of the molded body taken along line 2A-2A in FIG. 1 shows the first fiber-reinforced resin layer in the in-plane direction ( Figure 1 The cross section in the XY direction, Figure 2 B is along Figure 1 A schematic cross-sectional view of the molded body taken along line 2B-2B in FIG. 1 shows the second fiber-reinforced resin layer in the in-plane direction ( Figure 1 The cross section in the XY direction in FIG.

[0043] [ Figure 3 ] Figure 3 To follow Figure 1 A schematic cross-sectional view of the rib portion along line 3-3 in FIG. 1 , showing the rib portion in the in-plane direction ( Figure 1 The cross section in the XZ direction.

[0044] [ Figure 4 ] Figure 4 for Figure 2 A is an enlarged cross-sectional view of a portion of the first fiber-reinforced resin layer in contact with the rib.

[0045] [ Figure 5 ] Figure 5 This is a flowchart of a method for producing the above-mentioned fiber-reinforced resin molded article according to another embodiment of the present invention.

[0046] [ Figure 6 ] Figure 6 This is a perspective view showing a schematic shape of a mold used for producing a molded body in another embodiment of the present invention.

[0047] [ Figure 7 ] Figure 7 A is along Figure 6 The cross-sectional view of the cavity along line 7A-7A in FIG. 1 shows the cavity in the long side direction ( Figure 6 The cross section in the XZ direction, Figure 7 B is along Figure 6 A cross-sectional view of the cavity portion along line 7B-7B in FIG. 1 shows the cavity portion in the width direction ( Figure 6 The cross section in the YZ direction.

[0048] [ Figure 8 ] Figure 8It is a schematic cross-sectional view of a mold, showing a state in which the first fiber-reinforced resin and the second fiber-reinforced resin are arranged in the mold in step S510.

[0049] [ Figure 9 ] Figure 9 For mold and Figure 7 The schematic cross-sectional view of the same cross section shows how the first fiber-reinforced resin and the second fiber-reinforced resin are molded in step S520 .

[0050] [ Figure 10 ] Figure 10 For mold and Figure 7 The schematic cross-sectional view of the same cross section shows how the first fiber-reinforced resin and the second fiber-reinforced resin are molded in step S520 . DETAILED DESCRIPTION

[0051] [Fiber-reinforced resin molded article]

[0052] Figure 1 This is a perspective view showing an exemplary structure of a fiber-reinforced resin molded article according to one embodiment of the present invention.

[0053] The fiber-reinforced resin molded article 100 includes: a first fiber-reinforced resin layer 110 and a second fiber-reinforced resin layer 120, each having different fiber lengths and orientations; and a rib 130 disposed in contact with the surface of the first fiber-reinforced resin layer 110 and projecting from the surface of the first fiber-reinforced resin layer 110 toward the side opposite to the second fiber-reinforced resin layer 120. The first fiber-reinforced resin layer 110 and the second fiber-reinforced resin layer 120 are both sheet-shaped fiber-reinforced resins. Figure 1 The rib 130 is a protrusion made of fiber-reinforced resin and is integrally molded with the first fiber-reinforced resin layer 110 and the second fiber-reinforced resin layer 120.

[0054] As described below, molded article 100 can be produced by laminating a fiber-reinforced resin (first fiber-reinforced resin) serving as the material for first fiber-reinforced resin layer 110 and a fiber-reinforced resin (second fiber-reinforced resin) serving as the material for second fiber-reinforced resin layer 120, and then performing press molding within a mold having a space shaped like rib 130 on the first fiber-reinforced resin side. It is believed that during press molding, the matrix resin of the second fiber-reinforced resin melts and flows through the first fiber-reinforced resin (between the reinforcing fibers 112 contained in the first fiber-reinforced resin) along with the reinforcing fibers of the second fiber-reinforced resin. The matrix resin and reinforcing fibers of the second fiber-reinforced resin that flow through this flow, along with the matrix resin of the first fiber-reinforced resin that is extruded by this flow, fill the space shaped like rib 130, thereby forming rib 130.

[0055] Figure 2 A is along Figure 1 The cross-sectional view of the molded body 100 taken along line 2A-2A in FIG. 1 shows the first fiber-reinforced resin layer 110 in the in-plane direction ( Figure 1 The cross section in the XY direction in FIG. Figure 2 B is along Figure 1 The cross-sectional view of the molded body 100 taken along line 2B-2B in FIG. 1 shows the second fiber-reinforced resin layer 120 in the in-plane direction ( Figure 1 The cross section in the XY direction in FIG.

[0056] (First fiber-reinforced resin layer)

[0057] The first fiber reinforced resin layer 110 includes: Figure 2 A) oriented in the Y direction of the plurality of reinforcing fibers 112; and a matrix resin 114 impregnated in the reinforcing fibers 112 (see Figure 2 A) It should be noted that, in the first fiber-reinforced resin layer 110 , the reinforcing fibers 112 may be partially cut by forming incisions (slits).

[0058] The first fiber-reinforced resin layer 110 can be formed from a film-like fiber-reinforced resin (UD sheet) comprising a plurality of unidirectionally oriented reinforcing fibers 112 and a resin composition (matrix resin 114) impregnated into the reinforcing fibers. In this case, the first fiber-reinforced resin layer 110 can be formed as a single layer using a single UD sheet, or it can be formed as a multi-layered first fiber-reinforced resin layer 110 using multiple UD sheets. When the first fiber-reinforced resin layer 110 is formed from multiple UD sheets, the layers comprising the first fiber-reinforced resin layer 110 (layers from each UD sheet) can be stacked so that the orientation angles of the reinforcing fibers 112 are uniform, or they can be stacked so that the orientation angles of the reinforcing fibers 112 vary from layer to layer. To improve the strength of the first fiber-reinforced resin layer 110 against loads applied from multiple directions, the first fiber-reinforced resin layer 110 preferably comprises multiple layers in which the orientation angles of the reinforcing fibers 112 vary from layer to layer. At this time, the above-mentioned multiple layers may include only one or more layers in which the orientation angle of the reinforcing fibers 112 is different in only one direction (for example, one or more layers in which the orientation angle is 90° relative to the layer (0°) serving as a reference), or may include one or more layers in which the orientation angle of the reinforcing fibers 112 is different in directions different from each other (for example, one or more layers in which the orientation angles are 45°, 90°, and 135° relative to the layer (0°) serving as a reference). When the first fiber-reinforced resin layer 110 includes a plurality of layers in which the orientation angles of the reinforcing fibers 112 differ from layer to layer, it is preferable to set the orientation angles of the reinforcing fibers 112 contained in each layer (e.g., 0° / 90° / 0°, 0° / 45° / 90° / 135° / 135° / 90° / 45° / 0°, etc.) so that the orientation angles of the reinforcing fibers 112 contained in the plurality of layers become pseudo-isotropic (i.e., layers in which the reinforcing fibers 112 are uniformly oriented in all directions when viewed from the entire first fiber-reinforced resin layer 110).

[0059] It should be noted that, from the perspective of facilitating the passage of the reinforcing fibers and matrix resin of the second fiber-reinforced resin layer 120 between the reinforcing fibers 112 during molding of the molded article 100, thereby facilitating the formation of taller ribs 130, the angle at which the reinforcing fibers 112 of the layer closest to the ribs among the layers included in the first fiber-reinforced resin layer 110 are oriented is preferably substantially the same as the longitudinal direction of the ribs 130. In this specification, the term "substantially the same" means that the smaller of the two values ​​relative to the larger value is within a range of 10%.

[0060] To further enhance the strength of the rib 130, the first fiber-reinforced resin layer 110 preferably includes a layer in which the reinforcing fibers 112 are oriented at an angle different from the longitudinal direction of the rib 130. In such a layer, the reinforcing fibers 112 contained in the layer act as a wedge, securing the reinforcing fibers spanning the first fiber-reinforced resin layer 110 and the rib 130. This prevents the reinforcing fibers of the rib 130 from collapsing, and thus reduces the risk of damage to the rib 130. In particular, if the layers of the first fiber-reinforced resin layer 110 located closest to the rib have reinforcing fibers 112 oriented at an angle different from the longitudinal direction of the rib 130, the strength of the rib 130 is likely to be enhanced. Furthermore, if the first fiber-reinforced resin layer 110 includes a layer in which the reinforcing fibers 112 are oriented at the same angle as the longitudinal direction of the rib 130, or at a 90° angle relative to the longitudinal direction of the rib 130, the rib's appearance is likely to be improved.

[0061] When formed from multiple UD sheets, the number of first fiber-reinforced resin layers 110 is preferably 2 or more and 24 or less. The fewer the number of layers, the greater the formability of the first fiber-reinforced resin layer 110, making it easier to form a molded article 100 having a wider variety of shapes. The greater the number of layers, the easier it is to stack the reinforcing fiber layers in a manner that controls strength in specific directions. The fewer the number of layers, the easier it is to form taller ribs 130. From this perspective, the more preferably 2 or more and 18 or less layers are preferred.

[0062] The fiber length (average fiber length) of the reinforcing fibers 112 can be set to 15 mm or greater, preferably 20 mm or greater, more preferably 100 mm or greater, and even more preferably 500 mm or greater. The longer the fiber length of the reinforcing fibers 112, the higher the strength of the first fiber-reinforced resin layer 110, and the higher the strength of the molded article 100 imparted by the first fiber-reinforced resin layer 110. The upper limit of the fiber length of the reinforcing fibers 112 can be appropriately determined depending on the shape and size of the molded article 100, and can be, for example, 50 mm or less.

[0063] The average diameter of the reinforcing fibers 112 is preferably 1 μm to 20 μm, more preferably 4 μm to 10 μm. A larger average diameter of the reinforcing fibers 112 increases the strength of the first fiber-reinforced resin layer 110, and thus improves the strength of the molded article 100 imparted by the first fiber-reinforced resin layer 110. A smaller average diameter of the reinforcing fibers 112 facilitates the passage of the reinforcing fibers and matrix resin of the second fiber-reinforced resin layer 120 between the reinforcing fibers 112 during molding of the molded article 100, thereby facilitating the formation of taller ribs 130.

[0064] The type of reinforcing fiber 112 is not particularly limited, and carbon fiber, glass fiber, aramid fiber, alumina fiber, silicon carbide fiber, boron fiber, and metal fiber can be used as the reinforcing fiber. Among these, carbon fiber and glass fiber are preferred, and carbon fiber is more preferred.

[0065] The reinforcing fibers 112 may be sized with a sizing agent. The sizing agent is not particularly limited, but is preferably a modified polyolefin, more preferably a modified polyolefin containing a metal carboxylate salt. Such modified polyolefins are obtained, for example, by grafting carboxylic acid groups, carboxylic anhydride groups, or carboxylate ester groups onto the polymer chain of an unmodified polyolefin, and forming salts between these functional groups and metal cations.

[0066] Above-mentioned unmodified polyolefin is preferably the ethylene polymer more than 50 mol % or the propylene polymer more than 50 mol % from the content of the structural unit of ethylene.In the example of above-mentioned ethylene polymer, comprise the copolymer of alpha-olefin of ethylene homopolymer and ethylene and 3 above and 10 below of carbon number.In the example of above-mentioned propylene polymer, comprise the copolymer of alpha-olefin of propylene homopolymer and propylene and ethylene or 4 above and 10 below of carbon number.Above-mentioned unmodified polyolefin is preferably homopolypropylene, homopolyethylene, ethylene·propylene copolymer, propylene·1-butene copolymer or ethylene·propylene·1-butene copolymer.The alpha-olefin that constitutes these unmodified polyolefins and modified polyolefin can derive from fossil fuel, also can derive from biomass raw material, also can be their mixture.

[0067] The reinforcing fibers 112 are arranged in a unidirectional orientation and are present in the matrix resin 114 .

[0068] The material of the matrix resin 114 is not particularly limited and can be a thermoplastic resin or a thermosetting resin. The matrix resin 114 can be a crystalline resin or an amorphous resin. These thermoplastic resins and thermosetting resins can be derived from fossil fuels, biomass raw materials, or a mixture thereof.

[0069] Examples of the above-mentioned thermoplastic resins include polyolefin resins including polyethylene, polypropylene, polybutene, and poly-4-methyl-1-pentene, polyamide resins, polyester resins, polystyrene resins, thermoplastic polyimide resins, polyamideimide resins, polycarbonate resins, polyphenylene ether resins, polyphenylene sulfide resins, polyacetal resins, acrylic resins, polyetherimide resins, polysulfone resins, polyetherketone resins, polyetheretherketone resins, polyarylate resins, polyethernitrile resins, vinyl chloride resins, ABS resins, and fluororesins.

[0070] Examples of the thermosetting resin include epoxy resin, phenolic resin, melamine resin, urea resin, diallyl phthalate resin, silicone resin, polyurethane resin, furan resin, ketone resin, xylene resin, thermosetting polyimide resin, unsaturated polyester resin, and diallyl terephthalate resin.

[0071] Among these, thermoplastic resins are preferred from the viewpoint of further improving the moldability of the first fiber-reinforced resin layer 110 and facilitating the passage of the reinforcing fibers and the matrix resin from the second fiber-reinforced resin layer 120 between the reinforcing fibers 112 during molding of the molded body 100. Among thermoplastic resins, polyamide resins and polyolefin resins are preferred, and polyolefin resins are more preferred, and polypropylene is even more preferred, from the viewpoint of enabling molding at lower temperatures and thus further improving production efficiency.

[0072] The matrix resin 114 can be a resin composition containing additives. Examples of the above-mentioned additives include known fillers (inorganic fillers, organic fillers), pigments, dyes, weather-resistant stabilizers, heat-resistant stabilizers, antistatic agents, antislip agents, antioxidants, mildew inhibitors, antibacterial agents, flame retardants, and softeners. For example, when the UD sheet is fused by irradiating a laser when manufacturing the molded body 100, the matrix resin 114 is preferably a resin composition containing a pigment that absorbs the laser of the irradiated wavelength. The above-mentioned pigment can be any pigment that absorbs light of any wavelength between 300 nm and 3000 nm, preferably carbon black.

[0073] In addition, the matrix resin 114 may contain other components such as resins other than those described above and short fibers shorter than the reinforcing fibers 112 .

[0074] The matrix resin 114 preferably has a melt flow rate (MFR), as measured in accordance with ASTM D1238 at 230°C and under a load of 2.16 kg, of 100 g / 10 min or higher, and more preferably 130 g / 10 min or higher and 500 g / 10 min or lower. When the MFR falls within this range, the reinforcing fibers and matrix resin from the second fiber-reinforced resin layer 120 easily pass between the reinforcing fibers 112 during molding of the molded article 100, facilitating the formation of taller ribs 130.

[0075] The content of the reinforcing fibers 112 (fiber volume fraction (Vf)) relative to the total volume of the first fiber-reinforced resin layer 110 is preferably 10% by volume to 70% by volume, more preferably 15% by volume to 60% by volume, and even more preferably 20% by volume to 60% by volume. A higher fiber volume fraction (Vf) improves the strength of the first fiber-reinforced resin layer 110 and the strength of the molded article 100 imparted by the first fiber-reinforced resin layer 110. A lower fiber volume fraction (Vf) makes it easier for the reinforcing fibers and matrix resin from the second fiber-reinforced resin layer 120 to pass between the reinforcing fibers 112 during molding of the molded article 100, facilitating the formation of taller ribs 130.

[0076] The thickness of the first fiber-reinforced resin layer 110 is preferably from 40 μm to 3000 μm, more preferably from 100 μm to 2000 μm, even more preferably from 150 μm to 1500 μm, and particularly preferably from 300 μm to 1200 μm. The greater the thickness of the first fiber-reinforced resin layer 110, the higher the strength of the first fiber-reinforced resin layer 110, and the higher the strength of the molded article 100 imparted by the first fiber-reinforced resin layer 110. The smaller the thickness of the first fiber-reinforced resin layer 110, the stronger the ribs 130 and the less likely they are to be damaged or cracked during molding, resulting in a more attractive appearance for the ribs 130. From the same perspective, the thickness of the first fiber-reinforced resin layer 110 is preferably smaller than the thickness of the second fiber-reinforced resin layer 120.

[0077] (Second fiber-reinforced resin layer)

[0078] The second fiber-reinforced resin layer 120 is formed by randomly arranging blocks 126 including a plurality of reinforcing fibers 122 oriented in one direction and a matrix resin 124 (see Figure 2 B) The second fiber-reinforced resin layer 120 gives the molded body 100 a marble-textured appearance due to the randomly arranged plurality of blocks. Furthermore, the second fiber-reinforced resin layer 120 also serves as the material for the ribs 130 during molding.

[0079] The second fiber-reinforced resin layer 120 can be formed using a sheet material (hereinafter also referred to as a "random sheet") that is formed by cutting a UD sheet into small pieces and then forming a plurality of randomly arranged short slices into a sheet using a known press molding machine. In this case, each short slice becomes each block 126 in the second fiber-reinforced resin layer 120.

[0080] The short slices are shaped to correspond to the fiber length and dispersion of the reinforcing fibers 122 in each block 126. The width of the short slices in the direction perpendicular to the orientation direction of the reinforcing fibers is preferably 3 mm or more and 50 mm or less. If the width in the above-mentioned direction is 3 mm or more, the formability of the short slices and the shaping property of the molded body 100 can be improved. If the width in the above-mentioned direction is 50 mm or less, the strength of the molded body can be further improved. From the above-mentioned viewpoint, the width in the above-mentioned direction is more preferably 10 mm or more and 25 mm or less.

[0081] In addition, the length of the short slice material in the orientation direction of the reinforcing fiber is preferably 5mm or more and 50mm or less. If the length in the above-mentioned direction is more than 5mm, the intensity of the molded body can be further improved. If the length in the above-mentioned direction is below 50mm, the moldability of the short slice material, the shaping property of the molded body 100, and the outward appearance of the molded body can be made all good. Consider from the above-mentioned viewpoint, the length in the above-mentioned direction is more preferably 10mm or more and 30mm or less.

[0082] In addition, the ratio of the length of the short slice material in the orientation direction of the reinforcing fiber to the width of the short slice material in the direction orthogonal to the orientation direction of the reinforcing fiber (aspect ratio: length / width) is preferably 0.5 or more and 5.0 or less. If the above-mentioned aspect ratio is more than 0.5, there is a tendency that the short slice material is not easy to bend and the strength of the molded body is improved. If the above-mentioned aspect ratio is 5.0 or less, the fiber shortens, and therefore there is a tendency that moldability is further improved. From the above-mentioned viewpoint, the above-mentioned aspect ratio is more preferably 1.0 or more and 3.0 or less.

[0083] By randomly placing the short slices (the orientation direction of the fibers is scattered in each short slice) and without gaps inside a mold of a press molding machine and performing press molding, a random sheet can be obtained in which the reinforcing fibers are oriented in the in-plane direction and the orientation direction in the in-plane direction is random. It should be noted that at this time, the short slices can also be placed non-randomly (the orientation direction of the fibers is the same, or although the orientation direction of the fibers of each short slice is biased, the overall orientation direction of the fibers is oriented) and press molded, so that the arrangement of the blocks 126 in the second fiber-reinforced resin layer 120 becomes non-random.

[0084] The fiber length (average fiber length) of the reinforcing fibers 122 included in each block 126 is shorter than the fiber length (average fiber length) of the reinforcing fibers 112 included in the first fiber-reinforced resin layer 110. The fiber length of the reinforcing fibers 122 is typically 50 mm or less, preferably 1 mm or more and 40 mm or less, more preferably 3 mm or more and 40 mm or less, and even more preferably 6 mm or more and 35 mm or less. The longer the fiber length of the reinforcing fibers 122, the higher the strength of the molded article 100 and the ribs 130. The shorter the fiber length of the reinforcing fibers 122, the higher the formability of the second fiber-reinforced resin layer 120. It also makes it easier for the reinforcing fibers 122 to pass between the reinforcing fibers 112 included in the first fiber-reinforced resin layer during molding of the molded article 100, thereby facilitating the formation of taller ribs 130.

[0085] The average diameter of the reinforcing fibers 122 is preferably 1 μm to 20 μm, more preferably 4 μm to 10 μm. The larger the average diameter of the reinforcing fibers 122, the higher the strength of the molded article 100 and the ribs 130. The smaller the average diameter of the reinforcing fibers 122, the easier it is for the reinforcing fibers 122 to pass between the reinforcing fibers 112 included in the first fiber-reinforced resin layer 110 during molding of the molded article 100, thereby facilitating the formation of taller ribs 130.

[0086] The type of reinforcing fibers 122 is not particularly limited, and carbon fibers, glass fibers, aramid fibers, alumina fibers, silicon carbide fibers, boron fibers, and metal fibers can be used as the reinforcing fibers. Of these, carbon fibers and glass fibers are preferred. Carbon fibers are more preferred because they are less likely to be cut when passing between the reinforcing fibers 112 included in the first fiber-reinforced resin layer 110 during molding, and because they can easily fill the ribs 130 with long reinforcing fibers 122, thereby increasing the strength of the ribs 130.

[0087] It should be noted that the reinforcing fibers 122 included in the second fiber-reinforced resin layer 120 may be the same type as the reinforcing fibers 112 included in the first fiber-reinforced resin layer 110 or may be different types of reinforcing fibers, but are preferably the same type of reinforcing fibers.

[0088] The reinforcing fibers 122 may be sized with a sizing agent. The sizing agent is not particularly limited, and various sizing agents described for the reinforcing fibers 112 included in the first fiber-reinforced resin layer 110 may be used in the same manner.

[0089] The reinforcing fibers 122 are arranged in a unidirectional orientation inside each block 126 and are present in the matrix resin 124 .

[0090] The material of the matrix resin 124 is not particularly limited and may be either a thermoplastic resin or a thermosetting resin. The matrix resin 124 may be either a crystalline resin or an amorphous resin. The various resins described for the matrix resin 114 included in the first fiber-reinforced resin layer 110 may be used as the matrix resin 124. Of these, thermoplastic resins are preferred from the perspective of allowing the matrix resin 114 to easily pass through the reinforcing fibers 112 included in the first fiber-reinforced resin layer 110 during molding of the molded article 100. Among thermoplastic resins, polyamide resins and polyolefin resins are preferred. Polyolefin resins are more preferred from the perspective of enabling molding at a relatively low temperature, thereby further improving production efficiency, and polypropylene is even more preferred.

[0091] It should be noted that the matrix resin 124 included in the second fiber-reinforced resin layer 120 may be the same type of resin as the matrix resin 114 included in the first fiber-reinforced resin layer 110, or a different type of resin. From the perspective of improving the fusion properties between the first fiber-reinforced resin layer 110 and the second fiber-reinforced resin layer 120, and the fusion properties between the first fiber-reinforced resin layer 110 and the rib 130, it is preferably the same type of resin. In particular, it is preferred that both the matrix resin 124 and the matrix resin 114 be polypropylene.

[0092] In addition, the matrix resin 124 may contain other components such as various additives, resins other than those described above, and short fibers shorter than the reinforcing fibers 122 , similarly to the matrix resin 114 included in the first fiber-reinforced resin layer 110 .

[0093] The melt flow rate (MFR) of the matrix resin 124, as measured in accordance with ASTM D1238 at 230°C and under a load of 2.16 kg, is preferably equal to or greater than the MFR of the matrix resin 114 included in the first fiber-reinforced resin layer 110. By setting the MFR of the matrix resin 124 to be equal to or greater than the MFR of the matrix resin 113 (in other words, by setting the fluidity of the matrix resin 124 to be equal, or by making the matrix resin 124 of the second fiber-reinforced resin layer 120 flow more easily), the reinforcing fibers 122 and the matrix resin 124 can more easily pass between the reinforcing fibers 112 included in the first fiber-reinforced resin layer 110 during molding of the molded article 100, thereby facilitating the formation of taller ribs 130.

[0094] Specifically, the melt flow rate (MFR) of the matrix resin 124, as measured in accordance with ASTM D1238 at 230°C and a load of 2.16 kg, is preferably 150 g / 10 min or higher, and more preferably 180 g / 10 min or higher and 600 g / 10 min or lower. When the MFR falls within this range, the reinforcing fibers and matrix resin from the second fiber-reinforced resin layer 120 easily pass between the reinforcing fibers 112 during molding of the molded article 100, facilitating the formation of taller ribs 130.

[0095] The content of the reinforcing fibers 122 relative to the total volume of the second fiber-reinforced resin layer 120 (fiber volume fraction (Vf)) is preferably 10% by volume to 65% by volume, more preferably 10% by volume to 60% by volume, and even more preferably 15% by volume to 55% by volume. A higher fiber volume fraction (Vf) improves the strength of the first fiber-reinforced resin layer 110 and the strength of the molded article 100 imparted by the first fiber-reinforced resin layer 110. A lower fiber volume fraction (Vf) makes it easier for the reinforcing fibers and matrix resin from the second fiber-reinforced resin layer 120 to pass between the reinforcing fibers 112 during molding of the molded article 100, facilitating the formation of taller ribs 130.

[0096] The mass of the reinforcing fibers 122 per unit area of ​​the second fiber-reinforced resin layer 120 is preferably 270 g / m 2 Above 3600g / m 2 Below, more preferably 350g / m 2 Above 2400g / m 2 Below, more preferably 400g / m 2 Above 1500g / m 2 The greater the mass of the reinforcing fibers 122 per unit area, the easier it is to pack more reinforcing fibers into the ribs 130, resulting in higher strength for the ribs 130. The less the mass of the reinforcing fibers 122 per unit area, the less likely the ribs 130 will be damaged or cracked during molding, resulting in a better appearance for the ribs 130.

[0097] The thickness of the second fiber-reinforced resin layer 120 is preferably 300 μm to 4000 μm, more preferably 300 μm to 3000 μm, even more preferably 400 μm to 2000 μm, and particularly preferably 400 μm to 1200 μm. The greater the thickness of the second fiber-reinforced resin layer 120, the easier it is to form taller ribs 130. The smaller the thickness of the second fiber-reinforced resin layer 120, the thinner the molded article 100 can be, further expanding the uses of the molded article 100.

[0098] (ribs)

[0099] The rib 130 is a convex structure formed on the first fiber-reinforced resin side by allowing the second fiber-reinforced resin material (reinforcement fibers 122 and matrix resin 124) to flow between the reinforcing fibers 112 of the first fiber-reinforced resin during molding of the molded article 100. In this embodiment, the first fiber-reinforced resin layer 110, the second fiber-reinforced resin layer 120, and the rib 130 are integrally formed using the aforementioned manufacturing method. In other words, no distinct bonding interface is formed between the first fiber-reinforced resin layer 110 and the rib 130, or between the first fiber-reinforced resin layer 110 and the second fiber-reinforced resin layer 120.

[0100] Figure 3 To follow Figure 1 The cross-sectional view of the rib 130 along line 3-3 in FIG. 1 shows the rib 130 in the in-plane direction ( Figure 1 It should be noted that for ease of understanding, Figure 3 A cross section of a portion of the first fiber reinforced resin layer 110 is also shown in FIG. Figure 3 The first fiber-reinforced resin layer 110 shown has a plurality of layers having reinforcing fibers 112 in different orientation directions. Figure 3 In the figure, the second fiber-reinforced resin layer 120 is not shown.

[0101] The rib 130 includes: a plurality of reinforcing fibers 132; a matrix resin 134 impregnated in the reinforcing fibers 132 (see Figure 3 The plurality of reinforcing fibers 132 are basically randomly dispersed, but may also be distributed in a single direction (eg, a direction away from the first fiber-reinforced resin layer 110 ) in the rib 130 . Figure 3 The orientation in this case does not need to be such that the plurality of reinforcing fibers are oriented and arranged in the same direction as in each block 126 in the first fiber-reinforced resin layer 110 and the second fiber-reinforced resin layer 120. Instead, the orientation is such that the orientation directions of the individual fibers are offset, but the plurality of reinforcing fibers 132 are arranged so as to have orientation in the orientation direction of the fibers as a whole.

[0102] In this embodiment, the rib 130 is uniformly arranged with reinforcing fibers 132 and uniformly impregnated with matrix resin 134. However, the arrangement of the reinforcing fibers 132 and matrix resin 134 is not limited to this. For example, the density of the reinforcing fibers 132 may be varied between the tip side (the side away from the first fiber-reinforced resin layer 110) and the root side (the side closer to the first fiber-reinforced resin layer 110) of the rib 130 (for example, the density of the reinforcing fibers 132 may be higher at the tip side of the rib 130 and lower at the root side of the rib 130, or the density of the reinforcing fibers 132 may be lower at the tip side of the rib 130 and higher at the root side of the rib 130). Alternatively, for example, the composition of the matrix resin 134 may be changed in stages at the tip and root sides of the rib 130 (for example, the tip side of the rib 130 may have a composition close to that of the matrix resin 114 included in the first fiber-reinforced resin layer 110, while the root side of the rib 130 may have a composition close to that of the matrix resin 124 included in the second fiber-reinforced resin layer 120). The arrangement of these reinforcing fibers 132 and matrix resin 134 can be changed by molding conditions (pressure, temperature, time, etc.).

[0103] The fiber length (average fiber length) of the reinforcing fibers 132 is shorter than the fiber length (average fiber length) of the reinforcing fibers 112 included in the first fiber-reinforced resin layer 110. Furthermore, the fiber length (average fiber length) of the reinforcing fibers 132 is approximately the same as the fiber length (average fiber length) of the reinforcing fibers 122 included in the second fiber-reinforced resin layer 120. The fiber length of the reinforcing fibers 132 is typically 50 mm or less, preferably 1 mm or more and 40 mm or less, more preferably 3 mm or more and 40 mm or less, and even more preferably 6 mm or more and 35 mm or less. The longer the fiber length of the reinforcing fibers 132, the higher the strength of the ribs 130. The shorter the fiber length of the reinforcing fibers 132, the higher the strength of the ribs 130.

[0104] The average diameter of the reinforcing fibers 132 is substantially the same as the average diameter of the reinforcing fibers 122 included in the second fiber-reinforced resin layer 120 , and is preferably 1 μm to 20 μm, and more preferably 4 μm to 10 μm.

[0105] The type of reinforcing fiber 132 is not particularly limited, and carbon fiber, glass fiber, aramid fiber, alumina fiber, silicon carbide fiber, boron fiber, and metal fiber can be used as the reinforcing fiber. Among these, carbon fiber and glass fiber are preferred, and carbon fiber is more preferred.

[0106] It should be noted that the reinforcing fibers 132 included in the rib 130 are the same type of reinforcing fibers as the reinforcing fibers 122 included in the second fiber-reinforced resin layer 120. The reinforcing fibers 132 included in the rib 130 may be the same type of reinforcing fibers as the reinforcing fibers 112 included in the first fiber-reinforced resin layer 110, or may be a different type of reinforcing fibers, but are preferably the same type of reinforcing fibers.

[0107] The reinforcing fibers 132 may be sizing-treated with a sizing agent, similarly to the reinforcing fibers 122 included in the second fiber-reinforced resin layer 120 .

[0108] The matrix resin 134 is the same type of resin as the matrix resin 114 included in the first fiber-reinforced resin layer 110 , the same type of resin as the matrix resin 124 included in the second fiber-reinforced resin layer 120 , or a mixture of these matrix resins 114 and 124 .

[0109] The content of the reinforcing fibers 132 relative to the total volume of the rib 130 (fiber volume fraction (Vf)) is preferably 10% by volume to 65% by volume, more preferably 10% by volume to 60% by volume, and even more preferably 15% by volume to 55% by volume. The greater the Vf, the higher the strength of the rib 130. The smaller the Vf, the easier it is to form the rib 130. It should be noted that the Vf of the rib 130 may be smaller than the Vf of the second fiber-reinforced resin layer 120.

[0110] The mass of the reinforcing fibers 132 per unit area of ​​the rib 130 is preferably 13000 g / m 2 Above 66000g / m 2 Below, more preferably 18000g / m 2 Above 56000g / m 2 Below, more preferably 23000g / m 2 Above 46000g / m 2 the following.

[0111] The length of the reinforcing fibers 132 contained in the ribs 130 and the amount of reinforcing fibers 132 used in the calculation of Vf can be calculated by heating the matrix resin 134 at the base of the ribs 130 to a temperature above its melting point but not affecting the reinforcing fibers 132, thereby melting the matrix resin 134. The ribs 130 are then extracted from the molded article 100. The extracted ribs 130 are then heated or treated with an organic resin to remove the matrix resin 134. The resulting reinforcing fibers 132 are then measured and calculated. The fiber length can be the average length of the 100 reinforcing fibers 132 obtained in this manner.

[0112] It should be noted that, when manufacturing the molded body 100, a portion of the reinforcing fibers 122 flowing from the second fiber-reinforced resin may not completely pass through the first fiber-reinforced resin layer 110 but may remain disposed inside the first fiber-reinforced resin layer 110 or may be disposed across the ribs 130 and the first fiber-reinforced resin layer 110 ( Figure 3 Reinforcement fibers 132a are shown.

[0113] Figure 4 for Figure 2 A is an enlarged cross-sectional view of a portion of the first fiber reinforced resin layer 110 that contacts the rib 130. Figure 4 As shown, in the portion of the first fiber-reinforced resin layer 110 that contacts the rib 130, a portion of the reinforcing fiber 112 may be locally bent and its orientation may be locally displaced when the reinforcing fiber 122 passes through. Figure 4 The reinforcing fibers 122 and the matrix resin 124 of the second fiber-reinforced resin pass through the bent displacement portion 112b of the reinforcing fibers 112.

[0114] The shape, size, and arrangement position of the rib 130 can be appropriately determined according to the application of the molded article 100 .

[0115] For example, the height of the rib 130 (the length from the connection point with the first fiber-reinforced resin layer 110 to the tip of the rib 130) is preferably 5 mm or greater, more preferably 10 mm or greater, and even more preferably 12 mm or greater. The upper limit of the height of the rib 130 is not particularly limited and can be, for example, 50 mm or less.

[0116] The length of the rib 130 (the length of the long side of the rib 130 in a plane parallel to the surface of the first fiber-reinforced resin layer 110) is preferably 100 mm or less, more preferably 80 mm or less, and even more preferably 60 mm or less. The lower limit of the length of the rib 130 is not particularly limited, and can be, for example, 5 mm or more.

[0117] The thickness of the rib 130 (the thickness in a direction perpendicular to the long sides of the rib 130 in a plane parallel to the surface of the first fiber-reinforced resin layer 110) is preferably 3 mm or less, more preferably 2.5 mm or less, and even more preferably 2 mm or less. The lower limit of the thickness of the rib 130 is not particularly limited, and can be, for example, 1 mm or more.

[0118] Thus, the molded article according to this embodiment has a structure in which the second fiber-reinforced resin layer 120, the first fiber-reinforced resin layer 110, and the ribs 130 are stacked in this order. Other layers may be placed between these layers and the ribs, but preferably, these layers and the ribs are stacked in direct contact without such other layers. It should be noted that the molded article 100 may have other layers outside these layers and the ribs. For example, the molded article 100 may have a transparent or translucent protective layer on the outer surface of the second fiber-reinforced resin layer 120 (the side opposite the ribs 130) to protect the appearance of the second fiber-reinforced resin layer 120 and to a degree that allows visual recognition of the second fiber-reinforced resin layer 120. The protective layer may be, for example, a resin film layer.

[0119] [Method for producing a fiber-reinforced resin molded article]

[0120] Figure 5 This is a flowchart of a method for producing the above-mentioned fiber-reinforced resin molded article 100 according to another embodiment of the present invention.

[0121] like Figure 5 As shown, the molded body 100 is manufactured by the following steps: a step of arranging the first fiber-reinforced resin and the second fiber-reinforced resin in a stacked manner in a mold for molding (step S510); and a step of molding the arranged first fiber-reinforced resin and the second fiber-reinforced resin inside the above-mentioned mold (step S520).

[0122] (Step S510: Arrangement of Fiber-Reinforced Resin)

[0123] In this step, the first fiber-reinforced resin and the second fiber-reinforced resin are stacked and arranged in a molding die.

[0124] Figure 6 This is a perspective view showing the schematic shape of the mold 600 used to manufacture the molded body 100 in this embodiment. The mold 600 has a core mold 610 and a cavity mold 620 arranged opposite to each other, and is configured to be able to close and open the mold by moving the core mold 610 and the cavity mold 620 relative to each other in the approaching direction and the separating direction. In the center of the molding surface of the cavity mold 620, there is a cavity 622 with the same shape as the rib 130 to be formed. Figure 6 As shown, the cavity portion 622 is a substantially rectangular parallelepiped space that opens toward the molding surface of the cavity mold 620 .

[0125] Figure 7 A is along Figure 6 The cross-sectional view of the cavity 622 along the line 7A-7A in FIG. 7A shows the cavity 622 in the long side direction ( Figure 6 The cross section in the XZ direction. Figure 7 B is along Figure 6The cross-sectional view of the cavity 622 along the line 7B-7B in FIG. 7B shows the cavity 622 in the width direction ( Figure 6 The cross section on the YZ direction in the figure. Figure 7 A and Figure 7 As shown in B, the edge of the opening of the cavity 622 is rounded. It should be noted that the shape of the cavity 622 is not limited thereto and can be arbitrarily determined according to the shape of the rib 130 of the molded body 100 to be manufactured.

[0126] Figure 8 This is a schematic cross-sectional view of mold 600, illustrating the placement of the first and second fiber-reinforced resins within the mold during this step. In this step, first fiber-reinforced resin 810, comprising a plurality of unidirectionally aligned reinforcing fibers 812 and a matrix resin 814, is placed on the molding surface of cavity mold 620, contacting the opening of cavity 622. Next, second fiber-reinforced resin 820, comprised of a plurality of smaller blocks 826 comprising a plurality of unidirectionally aligned reinforcing fibers 822 and a matrix resin 824, is layered on the surface of first fiber-reinforced resin 810 (the surface opposite cavity 622).

[0127] The first fiber-reinforced resin 810 is typically a UD sheet and forms the material of the first fiber-reinforced resin layer 110 in the molded article 100. Furthermore, the second fiber-reinforced resin 820 is typically a collection of short slices obtained by cutting the UD sheet into small pieces and forms the material of the second fiber-reinforced resin layer 120 in the molded article 100. Therefore, the reinforcing fibers 812 and matrix resin 814 included in the first fiber-reinforced resin 810 can be the reinforcing fibers 112 and matrix resin 114 described above for the first fiber-reinforced resin layer 110, while the reinforcing fibers 822 and matrix resin 824 included in the second fiber-reinforced resin 820 can be the reinforcing fibers 122 and matrix resin 124 described above for the second fiber-reinforced resin layer 120. The dimensions of the short slices (blocks 826) can be within the range described for the second fiber-reinforced resin layer 120.

[0128] It should be noted that, as described above, the molded article 100 may include multiple layers having different orientation directions of the reinforcing fibers 112 within the first fiber-reinforced resin layer 110. When producing such a first fiber-reinforced resin layer 110, in this step, multiple UD sheets may be stacked so that the orientation direction of the reinforcing fibers differs in each layer to produce the first fiber-reinforced resin layer 110.

[0129] The thickness of the first fiber-reinforced resin 810 is preferably 0.04 mm to 3 mm, more preferably 0.1 mm to 2 mm, even more preferably 0.15 mm to 1.5 mm, and particularly preferably 0.3 mm to 1.2 mm. The greater the thickness of the first fiber-reinforced resin 810, the higher the strength of the first fiber-reinforced resin layer 110, and the higher the strength of the molded article 100 imparted by the first fiber-reinforced resin layer 110. The smaller the thickness of the first fiber-reinforced resin 810, the better the moldability of the first fiber-reinforced resin 810, making it easier to produce molded articles 100 in various shapes.

[0130] The thickness of the first fiber reinforced resin 810 can be adjusted by the number of stacked UD sheets, etc. In this case, the stacked UD sheets may be pre-heated and fused together, or multiple UD sheets that are not fused together may be arranged inside the mold 600 .

[0131] The thickness of the second fiber-reinforced resin 820 is preferably greater than that of the first fiber-reinforced resin 810. By making the second fiber-reinforced resin 820 thicker, especially when the thickness of the first fiber-reinforced resin 810 is reduced to reduce the thickness of the molded article, the second fiber-reinforced resin layer 120 can be fully formed even after flowing into the ribs 130, and the marble texture of the molded article 100 imparted by the second fiber-reinforced resin layer 120 can be clearly formed. On the other hand, by making the first fiber-reinforced resin 810 thinner, the strength of the ribs 130 can be improved. It should be noted that the thickness of the second fiber-reinforced resin 820 may also be smaller than that of the first fiber-reinforced resin 810.

[0132] Specifically, the thickness of the second fiber-reinforced resin 820 is preferably 0.3 mm to 4 mm, more preferably 0.3 mm to 2.5 mm, further preferably 0.4 mm to 2 mm, and particularly preferably 0.4 mm to 1.2 mm.

[0133] The thickness of the second fiber-reinforced resin 820 can be adjusted by the number of short slices, etc. It should be noted that in this embodiment, the short slices can be pre-heated and fused to form a random sheet, and the random sheet can be arranged inside the mold 600 (on the first fiber-reinforced resin 810). Alternatively, a plurality of short slices that are not fused to each other can be randomly filled on the first fiber-reinforced resin 810 and then arranged inside the mold 600.

[0134] The mass of the reinforcing fibers 822 per unit area of ​​the arranged second fiber-reinforced resin 820 is preferably 270 g / m 2 Above 3600g / m 2 Below, more preferably 350g / m2 Above 2400g / m 2 Below, more preferably 400g / m 2 Above 1500g / m 2 The greater the mass of the reinforcing fibers 122 per unit area, the easier it is to pack more reinforcing fibers into the ribs 130, resulting in higher strength for the ribs 130. Furthermore, the ribs 130 are less likely to be damaged or cracked during molding, improving the appearance of the ribs 130. The smaller the mass of the reinforcing fibers 122 per unit area, the less likely burrs are to form on the surface of the second fiber-reinforced resin layer 120, improving the appearance of the molded article 100 (the aesthetic appearance of the surface on the second fiber-reinforced resin layer 120 side).

[0135] (Step S520: Molding of Fiber-Reinforced Resin)

[0136] In this step, the first fiber-reinforced resin 810 and the second fiber-reinforced resin 820 disposed inside the mold 600 in the previous step are pressurized inside the mold 600 to be molded.

[0137] Figure 9 and Figure 10 The figure shows the state of molding the first fiber reinforced resin 810 and the second fiber reinforced resin 820 in this process. Figure 7 In this process, the mold is closed, the inside of the mold 600 is heated by a heating unit (not shown), and the core mold 610 and the cavity mold 620 are pressed in a direction close to each other, thereby pressurizing the inside of the mold 600 (see Figure 9 ).

[0138] By the above-mentioned heating, the matrix resin 814 contained in the first fiber-reinforced resin 810 and the matrix resin 824 contained in the second fiber-reinforced resin 820 are melted. At this time, the reinforcing fibers 812 contained in the first fiber-reinforced resin 810 are long fibers and therefore do not move much, but the reinforcing fibers 822 contained in the second fiber-reinforced resin 820 are shorter and easier to move. Furthermore, when the matrix resin 824 melted by the above-mentioned pressurization flows into the interior of the cavity 622, the reinforcing fibers 822 that are easier to move also flow into the interior of the cavity 622. At this time, the reinforcing fibers 822 flow into the cavity 622 while pushing open the fiber gaps of the reinforcing fibers 812 contained in the first fiber-reinforced resin 810. Therefore, in the portion corresponding to the cavity 622, a portion of the reinforcing fibers 812 is locally bent and the orientation is locally displaced (see Figure 4 ).

[0139] As a result, the reinforcing fibers 822 flow into the cavity 622 together with the matrix resin 824 (and the matrix resin 814) (see Figure 10 The reinforcing fibers 822 are hardly cut when flowing in, and thus maintain substantially the same length as when contained in the second fiber-reinforced resin 820.

[0140] On the other hand, if the ribs are formed by injection molding, the reinforcing fibers are cut due to pressure from the injection molding machine during flow and injection, making it difficult to fill the ribs 130 with long reinforcing fibers. According to the inventors of this application, the maximum length of reinforcing fibers that can be filled into the ribs 130 during injection molding is approximately 2.5 mm. In contrast, in this embodiment, since the ribs 130 are formed without injection molding, the reinforcing fibers are less likely to be cut, making it easier to fill the ribs 130 with long reinforcing fibers. Consequently, ribs 130 of sufficient height can be formed, and their strength can be substantially improved.

[0141] Furthermore, according to the inventors' findings, it is difficult to form ribs 130 of sufficient height when only second fiber-reinforced resin 820 containing relatively short reinforcing fibers is placed in mold 600 and molded. This is presumably because during molding, reinforcing fibers 822 and matrix resin 824 of second fiber-reinforced resin 820 tend to flow in the in-plane direction and are less likely to move in the thickness direction (inward of cavity 622). Therefore, it is difficult to form ribs 130 of sufficient height using only second fiber-reinforced resin 820. In contrast, if first fiber-reinforced resin 810 is placed on the rib 130 side (cavity 622 side) of second fiber-reinforced resin 820, the in-plane movement of reinforcing fibers 822 and matrix resin 824 is suppressed by the shear resistance exerted by reinforcing fibers 812 of first fiber-reinforced resin 810. Meanwhile, movement in the thickness direction through interfibers of reinforcing fibers 812 is facilitated, making it easier to form ribs 130 of sufficient height.

[0142] It should be noted that even when only the first fiber-reinforced resin 810 is placed in the mold 600 for molding, it is difficult to form the ribs 130 of sufficient height. This is probably because the first fiber-reinforced resin 810 contains long-fiber reinforcing fibers 812 and therefore has low moldability.

[0143] Furthermore, even when the second fiber-reinforced resin 820 is disposed on the rib 130 side (cavity 622 side) of the first fiber-reinforced resin 810, it is difficult to form a rib 130 of sufficient height. This is believed to be because, unlike the method of the present embodiment described above, the movement of the reinforcing fibers 812 in the thickness direction through the interfibers is not promoted.

[0144] The heating temperature in this step can be any temperature at which the matrix resin 814 of the first fiber-reinforced resin 810 and the matrix resin 824 of the second fiber-reinforced resin 820 melt. If these matrix resins are thermoplastic resins, the heating temperature can be any temperature at which the thermoplastic resin melts, and can be set to a temperature that is at least the melting point of the matrix resin but not more than 50°C higher. If the matrix resin is a thermosetting resin, the heating temperature can be any temperature at which the thermosetting resin solidifies, and can be set to a temperature that is at least the solidification temperature of the matrix resin but not more than 50°C higher. It should be noted that the melting point of the matrix resin mentioned above refers to the higher of the melting point of the matrix resin 814 of the first fiber-reinforced resin 810 and the melting point of the matrix resin 824 of the second fiber-reinforced resin 820. Furthermore, the solidification temperature of the matrix resin mentioned above refers to the higher of the solidification temperature of the matrix resin 814 of the first fiber-reinforced resin 810 and the solidification temperature of the matrix resin 824 of the second fiber-reinforced resin 820. The pressure can be set to 0.5 MPa or more and 20 MPa or less. However, the pressurization method is not limited to the pressurization method using a press molding machine. Other pressurization methods include pressurization using a double belt press and autoclave method using an autoclave device.

[0145] [Other embodiments]

[0146] The above-described embodiments are exemplary embodiments of the present invention, and it goes without saying that the present invention may include embodiments other than the above-described embodiments within the scope of its core technical concept.

[0147] For example, the molded article may include other layers having a different structure from these layers between the ribs and the first fiber-reinforced resin layer, and between the first fiber-reinforced resin layer and the second fiber-reinforced resin layer. In this case, the other layers preferably do not easily hinder the flow of the reinforcing fibers to the ribs. For example, various resin layers may be used, such as a resin layer containing no reinforcing fibers or a resin layer containing reinforcing fibers in the form of short fibers.

[0148] Furthermore, the molded article may include other layers having a different structure from these layers outside the ribs, in portions of the first fiber-reinforced resin layer where no ribs are provided, or outside the second fiber-reinforced resin layer.

[0149] Furthermore, in the above embodiment, the first fiber-reinforced resin 810 and the second fiber-reinforced resin 820 are heated inside the mold 600. However, the first fiber-reinforced resin 810 and the second fiber-reinforced resin 820 may be heated outside the mold 600 to a temperature above their melting point and then placed inside the mold 600. In other words, the first fiber-reinforced resin 810 and the second fiber-reinforced resin 820 may be heated before steps S510 and S520.

[0150] In the above embodiment, the molded article has only one rib, but the molded article may also have multiple ribs. The multiple ribs may all extend in the same direction or in different directions. Furthermore, the multiple ribs may be arranged in a cross pattern. Furthermore, when the molded article has a wall portion around the periphery of the first fiber-reinforced resin layer, the ends of the ribs may contact the wall portion.

[0151] The above-mentioned method for producing a molded article is not limited to including only these steps, and may include other steps as long as a desired molded article can be produced.

[0152] [use]

[0153] The fiber-reinforced resin molded article is not limited to a specific application, but is useful as a load-absorbing material in applications where a load is applied from a predetermined direction after being formed into a three-dimensional shape. Furthermore, when the rib 130 is embedded in and assembled with another component, the fiber-reinforced resin molded article exhibits high durability due to its high strength.

[0154] Example

[0155] The present invention will be described in detail based on Examples, but the present invention is not limited to these Examples.

[0156] 1. Production of fiber-reinforced resin

[0157] 1-1. UD sheet (first fiber-reinforced resin)

[0158] A UD sheet (TAFNEX, manufactured by Mitsui Chemicals, Inc.) was used as the first fiber-reinforced resin. This UD sheet contained polypropylene and carbon fibers, had a fiber volume fraction (Vf) of 50% by volume, and had a thickness of 0.15 mm. The polypropylene had a melting point of 168°C as measured by DSC according to JIS K7121, and a melt flow rate (MFR) of 200.0 g / 10 min as measured at 230°C and a load of 2160 g according to ASTM D-1238.

[0159] 1-2. Random sheet (second fiber-reinforced resin)

[0160] 1-2-1. Preparation of random sheet 1

[0161] After the above-mentioned UD sheet is cut in a manner such that the length in the direction perpendicular to the orientation direction of the reinforcing fibers becomes 12.5 mm, a tape cutter H510 made by Hashima Co., Ltd. is used to cut in a manner such that the length in the direction along the orientation direction of the reinforcing fibers becomes 3.0 mm to obtain a short slice material. Next, 50.3 g of the short slice material is spread in a mold of 220 mm in length and 220 mm in width in such a way that the fiber direction becomes random. Using a mini test press made by Toyo Seiki Co., Ltd., the spread short slice material is preheated for 8 minutes at a temperature of 175 ° C and a pressure of 3 MPa, collided 5 times with a pressure of 175 ° C and 10 MPa, pressed for 2 minutes at a pressure of 175 ° C and 10 MPa, and cooled for 3 minutes at 15 ° C and 10 MPa to obtain a random sheet 1.

[0162] 1-2-2. Preparation of random sheet 2

[0163] A random sheet 2 was obtained in the same manner as in the preparation of the random sheet 1 except that the length in the direction along the orientation direction of the reinforcing fibers was set to 9.0 mm.

[0164] 1-2-3. Preparation of random sheet 3

[0165] A random sheet 3 was obtained in the same manner as in the preparation of the random sheet 1 except that the length in the direction along the orientation direction of the reinforcing fibers was set to 15.0 mm.

[0166] 1-2-4. Preparation of random sheet 4

[0167] A random sheet 4 was obtained in the same manner as in the preparation of the random sheet 1 except that the length in the direction along the orientation direction of the reinforcing fibers was set to 30.0 mm.

[0168] 1-2-5. Preparation of random sheet 5

[0169] Random sheet 5 was obtained in the same manner as in the preparation of random sheet 3 except that the amount of the short slices to be placed in the mold was changed to 62.9 g.

[0170] 1-2-6. Preparation of random sheet 6

[0171] Random sheet 6 was obtained in the same manner as in the preparation of random sheet 3 except that the amount of the short slices to be placed in the mold was changed to 37.8 g.

[0172] 1-2-7. Preparation of random sheet 7

[0173] A random sheet 7 was obtained in the same manner as in the preparation of the random sheet 1 except that the length in the direction along the orientation direction of the reinforcing fibers was set to 55.0 mm.

[0174] 2. Production of the molded body

[0175] 2-1. Preparation of Molded Body 1 (Example 1)

[0176] 2-1-1. Preparation of Laminated Body 1

[0177] Two UD sheets were placed on the surface of a random sheet 1 so that the orientation directions of the reinforcing fibers of the UD sheets formed an angle of 90° (0° / 90°). Using a mini test press manufactured by Toyo Seiki Co., Ltd., the random sheet and the UD sheet were preheated at 175°C and a pressure of 3 MPa for 8 minutes, collided five times at 175°C and a pressure of 10 MPa, then pressed at 175°C and a pressure of 10 MPa for 2 minutes, and cooled at 15°C and 10 MPa for 3 minutes to obtain a laminate 1.

[0178] 2-1-2. Shaping

[0179] The laminate 1 is arranged on the UD sheet side so that the rib side and the random sheet side are on the opposite side to the rib. Figure 6 and Figure 7 The laminate 1 was placed in the mold described above. At this time, the direction of orientation of the reinforcing fibers of the UD sheet in contact with the random sheet of the two UD sheets (0° direction) was aligned with the longitudinal direction of the rib of the mold (the directions of orientation of the reinforcing fibers of the two UD sheets were 0° and 90°, respectively, from the random sheet side relative to the longitudinal direction of the rib). The laminate 1 was heated at 240°C for 2 minutes using a DH832 oven manufactured by Yamato Scientific Co., Ltd., and then pressurized for 1 minute at a mold temperature of 145°C and a pressure of 5 MPa using a 250t press machine manufactured by Ogihara Producing Co., Ltd., followed by cooling at a cooling rate of 17°C / min to a mold temperature of 90°C while maintaining the pressurization, to obtain a shaped body (molded body 1).

[0180] It should be noted that the following molds were used as molds: the size of the molding surface in the longitudinal direction (the long side direction of the ribs, Figure 6 L1) is 220mm, and in the transverse direction (the width direction of the rib, Figure 6 L2) is 220mm. As for the shape of the cavity portion for forming the rib, the length of the rib ( Figure 7 A's L3) is 20 mm, the length of the rib root ( Figure 7 A's L4) is 22 mm, and relative to the width direction of the rib, the width of the rib ( Figure 7 B's L5) is 2mm, the width of the root of the rib ( Figure 7B's L6) is 4mm, the height of the rib ( Figure 7 A. Figure 7 B's L7) is 15mm.

[0181] 2-2. Preparation of Molded Articles 2 to 4 (Examples 2 to 4)

[0182] Laminated bodies 2 to 4 were obtained in the same manner as in the preparation of the molded body 1 except that random sheets 2 to 4 were used instead of the random sheet 1, thereby obtaining molded bodies 2 to 4.

[0183] 2-3. Preparation of Molded Articles 5 to 6 (Examples 5 to 6)

[0184] The laminate 3 is arranged in the mold in such a manner that the direction of orientation of the reinforcing fibers of the UD sheet in contact with the random sheet (0° direction) becomes 45° relative to the long side direction of the rib of the mold (so that the directions of orientation of the reinforcing fibers of the two UD sheets become 45° and -45° respectively from the random sheet side relative to the long side direction of the rib). Except for this, the same operation as that of the preparation of the molded body 3 is performed to obtain the molded body 5.

[0185] The laminate 3 is arranged in the mold in such a manner that the direction of orientation of the reinforcing fibers of the UD sheet in contact with the random sheet (0° direction) becomes 90° relative to the long side direction of the rib of the mold (so that the directions of orientation of the reinforcing fibers of the two UD sheets become 90° and 0° relative to the long side direction of the rib from the random sheet side, respectively). Except for this, the same operation as that of the molded body 3 is performed to obtain a molded body 6.

[0186] 2-4. Preparation of Molded Body 7 (Example 7)

[0187] 2-4-1. Preparation of laminate 7

[0188] Four UD sheets were placed on the surface of the random sheet 3 so that the angles formed by the orientation directions of the reinforcing fibers of the UD sheets between the layers were all 90° (0° / 90° / 0° / 90°). Otherwise, the same operation as that for preparing the laminate 1 was followed to obtain a laminate 7.

[0189] 2-4-2. Shaping

[0190] The laminate 7 is arranged in such a manner that the UD sheet side becomes the rib side and the random sheet side becomes the side opposite to the rib. Figure 6 and Figure 7At this time, the laminate 7 was arranged so that the direction of orientation of the reinforcing fibers of the UD sheet in contact with the random sheet among the four UD sheets (the 0° direction) was aligned with the longitudinal direction of the rib of the mold (so that the directions of orientation of the reinforcing fibers of the four UD sheets were 0°, 90°, 0°, and 90° in order from the random sheet side relative to the longitudinal direction of the rib). Otherwise, the same operation as that for producing the molded body 1 was followed to obtain the molded body 7.

[0191] 2-5. Preparation of Molded Body 8 (Example 8)

[0192] 2-5-1. Preparation of laminate 8

[0193] Eight UD sheets were placed on the surface of the random sheet 3 so that the angles formed by the orientation directions of the reinforcing fibers of the UD sheets between the layers were all 90° (0° / 90° / 0° / 90° / 0° / 90° / 0° / 90°). Otherwise, the same operation as that for the preparation of the laminate 1 was followed to obtain a laminate 8.

[0194] 2-5-2. Shaping

[0195] The laminate 8 is arranged on the UD sheet side so that the rib side and the random sheet side are opposite to the rib side. Figure 6 and Figure 7 At this time, the laminate 8 was arranged so that the direction of orientation of the reinforcing fibers of the UD sheet in contact with the random sheet among the eight UD sheets (the 0° direction) was aligned with the longitudinal direction of the rib of the mold (the directions of orientation of the reinforcing fibers of the eight UD sheets were 0°, 90°, 0°, 90°, 0°, 90°, 0°, and 90°, in order from the random sheet side, relative to the longitudinal direction of the rib). Otherwise, the same operation as that for producing the molded body 1 was followed to obtain the molded body 8.

[0196] 2-6. Preparation of Molded Articles 9 to 10 (Examples 9 to 10)

[0197] Laminated bodies 9 and 10 were respectively obtained in the same manner as in the preparation of the molded body 1 except that random sheets 5 and 6 were used instead of the random sheet 1, thereby obtaining molded bodies 9 and 10.

[0198] 2-7. Preparation of Molded Body 11 (Comparative Example 1)

[0199] 2-7-1. Preparation of laminate 11

[0200] Two UD sheets were placed on the surface of the random sheet 3 so that the angle formed by the orientation directions of the reinforcing fibers of the UD sheets was 90° (0° / 90°), and the random sheet 3 was further placed on the surface of the UD sheet. Otherwise, the same operation as that for the preparation of the laminate 1 was carried out to obtain a laminate 11.

[0201] 2-7-2. Shaping

[0202] The stacked body 11 is placed on Figure 6 and Figure 7 At this time, the laminate 11 is arranged so that the direction of orientation of the reinforcing fibers of the UD sheet on the rib side of the two UD sheets (0° direction) is aligned with the longitudinal direction of the rib of the mold (so that the directions of orientation of the reinforcing fibers of the two UD sheets are 0° and 90°, respectively, from the side opposite to the rib, relative to the longitudinal direction of the rib). Otherwise, the same operation as that for producing the molded body 1 is performed to obtain the molded body 11.

[0203] 2-8. Preparation of Molded Body 12 (Comparative Example 2)

[0204] The stack 3 is arranged on the surface of the substrate in such a manner that the random sheet side becomes the rib side and the UD sheet side becomes the side opposite to the rib. Figure 6 and Figure 7 At this time, the laminate 3 is arranged so that the direction of orientation of the reinforcing fibers of the UD sheet on the rib side of the two UD sheets (0° direction) is aligned with the longitudinal direction of the rib of the mold (so that the directions of orientation of the reinforcing fibers of the two UD sheets are 0° and 90°, respectively, from the side opposite to the rib, relative to the longitudinal direction of the rib). Otherwise, the same operation as that for producing the molded body 1 is followed to obtain a molded body 12.

[0205] 2-9. Preparation of Molded Body 13 (Comparative Example 3)

[0206] 2-9-1. Preparation of laminate 13

[0207] The six UD sheets were arranged so that the angles formed by the orientation directions of the reinforcing fibers of the UD sheets between the layers were all 90° (0° / 90° / 0° / 90° / 0° / 90°).

[0208] 2-9-2. Shaping

[0209] The stacked body 13 is placed on Figure 6 and Figure 7At this time, the laminate 13 was arranged so that the direction of orientation of the reinforcing fibers of the UD sheet closest to the rib side among the six UD sheets (the 0° direction) was aligned with the longitudinal direction of the rib of the mold (so that the directions of orientation of the reinforcing fibers of the six UD sheets were 0°, 90°, 0°, 90°, 0°, and 90°, respectively, from the side opposite to the rib, relative to the longitudinal direction of the rib). Otherwise, the same operation as that for producing the molded body 1 was followed to obtain the molded body 13.

[0210] 2-10. Preparation of Molded Body 14 (Comparative Example 4)

[0211] The random sheet 5 is arranged on Figure 6 and Figure 7 Otherwise, the same operation as that for forming the molded body 1 was carried out to obtain a molded body 14.

[0212] 3. Evaluation

[0213] 3-1. Rib height

[0214] The height of the ribs of the obtained molded articles was measured visually using a ruler, and the height of the ribs of each molded article was evaluated based on the following criteria.

[0215] ○The height of the rib is 15mm

[0216] The height of the rib is greater than 10mm and less than 15mm

[0217] × The height of the rib is less than 10mm

[0218] 3-2. Fiber Length of Rib Reinforcement Fibers

[0219] The base of the rib (the area 0 to 5 mm from the bottom) was heated to 180°C (a temperature above the melting point of polypropylene) with a soldering iron to melt the resin at the base. The rib was then removed by grasping the tip, taking care not to damage it. The removed rib was heated at 500°C for 3 minutes to thermally decompose the resin, leaving only the reinforcing fibers. 100 fibers were randomly selected from the resulting reinforcing fibers and their fiber lengths were measured using an optical microscope. The arithmetic mean of the 100 fiber lengths was taken as the fiber length of the reinforcing fibers in the rib.

[0220] 3-3. Vf of ribs

[0221] The resulting molded body was cut from the base using a reciprocating saw (EZ47A1PN2G manufactured by Panasonic Corporation) and the total weight (g) of the ribs was measured. Subsequently, the resin was thermally decomposed by heating at 500°C for 30 minutes using a muffle furnace (FC300 manufactured by Yamato Scientific Co., Ltd.). The weight was then measured again to calculate the fiber content (g) in the ribs. The resin content (g) was also calculated assuming that only the resin component was present in addition to the reinforcing fibers, and the density of the reinforcing fibers was set to 1.8 g / cm. 3 , the resin component density is set to 0.9g / cm 3 , calculate Vf.

[0222] 3-4. Appearance of the ribs

[0223] For those evaluated as "◯" for rib height, the appearance of the rib was visually observed, and the appearance of the rib of each molded article was evaluated based on the presence or absence of damage according to the following criteria.

[0224] No damage to the ribs

[0225] ○ Damage less than 2mm in length was confirmed on the ribs

[0226] △ Damage of 2mm or more and less than 5mm in length was confirmed on the ribs

[0227] × Damage of 5mm or more in length is confirmed on the ribs

[0228] 3-5. Rib failure load

[0229] For those with a rib height rating of "○," the molded body was cut into a size of 80 mm in width and 80 mm in length, centered on the rib. A portion of the cut molded body, 20 mm from either end in a direction perpendicular to the longitudinal direction of the rib, was fixed. A compressive load was applied at a rate of 2 mm / min within a width of 5 mm and a length of 5 mm at the upper end of the center portion of the rib in the longitudinal direction. The applied load from the start of application until the load dropped was defined as the breaking load of the rib. It should be noted that STRONGRAPH VE55D manufactured by Toyo Seiki Co., Ltd. was used for the breaking load evaluation.

[0230] Based on the obtained breaking load value, the breaking load of the rib portion of each molded article was evaluated according to the following criteria.

[0231] ◎The breaking load is 420N or more

[0232] ○The breaking load is 300N or more and less than 420N

[0233] △The breaking load is 180N or more and less than 300N

[0234] × Breaking load is less than 180N

[0235] 3-6. Appearance of the Molded Product

[0236] The surface of the molded body opposite to the side where the rib was formed was visually observed, and the appearance of each molded body was evaluated based on the following criteria.

[0237] ○Marbled appearance

[0238] × Does not have a marbled appearance

[0239] Tables 1 to 3 show the layer configurations of Molded Articles 1 to 14 (the order in which the materials used in the production were stacked, the fiber length in the random sheet, the thickness of the random sheet, the mass per unit area of ​​the reinforcing fibers contained in the random sheet, and the thickness of the UD sheet), as well as the results of the above evaluations. It should be noted that "RC" and "UDS" in Tables 1 to 3 represent random sheets and UD sheets, respectively. Furthermore, the orientation angles of the second layer in Tables 1 to 3 represent the angles formed by the orientation directions of the reinforcing fibers of the plurality of UD sheets constituting the second layer relative to the longitudinal direction of the rib. The upper side in the table represents the side opposite to the rib, and the lower side represents the rib side. These indicate that the UD sheets were stacked in the order in which the angles formed by the reinforcing fibers of the sheets reached the angles listed in the table.

[0240] [Table 1]

[0241]

[0242] [Table 2]

[0243]

[0244] [Table 3]

[0245]

[0246] As can be seen from Tables 1 to 3, in a molded article having a first fiber-reinforced resin layer comprising a plurality of reinforcing fibers arranged in a unidirectional orientation and a matrix resin, and a second fiber-reinforced resin layer formed by arranging blocks comprising a plurality of reinforcing fibers and a matrix resin arranged in a unidirectional orientation, by having a configuration in which a rib comprising a plurality of reinforcing fibers and a matrix resin protrudes from the surface of the first fiber-reinforced resin layer toward the side opposite to the second fiber-reinforced resin layer, it is possible to form a rib of a predetermined height without substantially cutting the reinforcing fibers.

[0247] This application claims the benefit of priority from Japanese Patent Application No. 2023-020022, filed on February 13, 2023. All matters described in the specification, claims, and drawings of that application at the time of filing are incorporated herein by reference.

[0248] Industrial applicability

[0249] The fiber-reinforced resin molded article according to the present invention has high rib strength, thereby improving strength. Therefore, the present invention opens up the possibility of using fiber-reinforced resin in a wider range of applications and is expected to contribute to the development of various fields related to fiber-reinforced resins.

[0250] Description of Reference Numerals

[0251] 100Fiber-reinforced resin molded body

[0252] 110 1st fiber reinforced resin layer

[0253] 112 Reinforcement Fiber

[0254] 112b displacement unit

[0255] 114 base resin

[0256] 120 2nd fiber reinforced resin layer

[0257] 122 Reinforcement Fiber

[0258] 124 base resin

[0259] 126 blocks

[0260] 130 ribs

[0261] 132, 132a reinforcing fiber

[0262] 134 base resin

[0263] 600 mold

[0264] 610 core mold

[0265] 620 cavity mold

[0266] 622 Cavity

[0267] 810 No.1 fiber reinforced resin

[0268] 812 reinforcement fiber

[0269] 814 base resin

[0270] 820 2nd fiber reinforced resin

[0271] 822 reinforcement fiber

[0272] 824 base resin

[0273] 826 blocks

Claims

1. A fiber-reinforced resin molded article comprising: a first fiber-reinforced resin layer comprising a plurality of reinforcing fibers arranged in a unidirectional orientation and a matrix resin; a second fiber-reinforced resin layer comprising randomly arranged blocks of a plurality of reinforcing fibers oriented in one direction and a matrix resin; and The rib protrudes from the surface of the first fiber-reinforced resin layer toward the side opposite to the second fiber-reinforced resin layer and includes a plurality of reinforcing fibers and a matrix resin.

2. The fiber-reinforced resin molded article according to claim 1, wherein The first fiber-reinforced resin layer, the second fiber-reinforced resin layer, and the rib are integrally molded.

3. The fiber-reinforced resin molded article according to claim 1 or 2, wherein: The first fiber-reinforced resin layer has a displaced portion where the orientation of the plurality of arranged reinforcing fibers is displaced at a location where the rib is formed.

4. The fiber-reinforced resin molded article according to any one of claims 1 to 3, wherein An average fiber length of the reinforcing fibers included in the second fiber-reinforced resin layer is substantially the same as an average fiber length of the reinforcing fibers included in the rib portion.

5. The fiber-reinforced resin molded article according to any one of claims 1 to 4, wherein A portion of the reinforcing fibers included in the rib portion exists across the rib portion and the first fiber-reinforced resin layer.

6. The fiber-reinforced resin molded article according to any one of claims 1 to 5, wherein The height of the rib is greater than 5 mm.

7. The fiber-reinforced resin molded article according to any one of claims 1 to 6, wherein The first fiber-reinforced resin layer has a thickness of 40 μm to 3000 μm.

8. The fiber-reinforced resin molded article according to any one of claims 1 to 7, wherein The second fiber-reinforced resin layer has a thickness of 300 μm to 4000 μm.

9. The fiber-reinforced resin molded article according to any one of claims 1 to 8, wherein The first fiber-reinforced resin layer, the second fiber-reinforced resin layer, and the ribs all contain polyolefin resin as the matrix resin.

10. The fiber-reinforced resin molded article according to any one of claims 1 to 9, wherein The average fiber length of the reinforcing fibers included in the second fiber-reinforced resin layer is 1 mm to 40 mm.

11. A method for producing a fiber-reinforced resin molded body, comprising: The step of arranging a first fiber-reinforced resin and a plurality of second fiber-reinforced resins in a laminated manner inside a mold, wherein the first fiber-reinforced resin comprises a plurality of reinforcing fibers arranged in a unidirectional orientation and a matrix resin, and the plurality of second fiber-reinforced resins are randomly assembled blocks each comprising a plurality of reinforcing fibers arranged in a unidirectional orientation and a matrix resin and having a smaller size than the first fiber-reinforced resin; and a step of molding the first fiber-reinforced resin and the plurality of second fiber-reinforced resins arranged in the mold; The mold has a cavity for molding a molded body having ribs through the molding step. In the arranging step, the first fiber-reinforced resin is arranged on the cavity side relative to the second fiber-reinforced resin.

12. The method for producing a fiber-reinforced resin molded article according to claim 11, wherein: In the arrangement step, the plurality of second fiber-reinforced resins are arranged so that the mass per unit area of ​​the reinforcing fibers of the plurality of second fiber-reinforced resins is 270 g / m 2 Above 3600g / m 2 The following configuration is made inside the mold.

13. The method for producing a fiber-reinforced resin molded article according to claim 11 or 12, wherein: In the arranging step, the first fiber-reinforced resin having a thickness of 0.01 mm to 0.5 mm is arranged inside the mold.

14. The method for producing a fiber-reinforced resin molded article according to any one of claims 11 to 13, wherein: In the arrangement step, the plurality of second fiber-reinforced resins having an average fiber length of the reinforcing fibers of 1 mm to 40 mm are arranged inside the mold.

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