Molded article provided with multiple holes

Abstract

To solve the problem that when holes are provided in a composite material using a conventional hole-punching method, reinforced fiber contained around the holes is cut and thereby strength around holes decreases.SOLUTION: According to a molded article containing discontinuous reinforced fiber and a resin, the molded article comprises multiple holes h and a base part, and the base part comprises a bridge part sandwiched between a hole hi=k and a hole hi=k+1. The bridge part comprises an area where the reinforced fiber is continuously arranged so as to connect the hole hi=k with the hole hi=k+1 across the bridge part. According to the molded article, a value of an area ratio Cf when cross-sections of the reinforced fiber exposed to inner wall peripheral faces C of the holes h are observed is smaller than a value of a ratio Vf of fiber volume contained in the entire molded article.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a molded article having a plurality of holes and a method for producing the same. [Background technology]

[0002] When holes are made in a molded product, they are made using a punching machine with a press, a drill, etc. The shapes and sizes of the holes are diverse, and they are generally made at regular intervals.

[0003] Patent Document 1 provides a method and an apparatus for efficiently producing cut bodies even when the cutting blade has a closed loop structure. It describes that the positional accuracy of the cutting blade can be maintained high even when cutting composite materials continuously, and that even when a cutting blade having a closed loop structure is used, the cut pieces can be smoothly discharged, and the composite material can be continuously cut to produce cut bodies.

[0004] Patent Document 2 describes a method for manufacturing a punched plate by drilling multiple holes in a single plate. It proposes punched holes that have no burrs on the surface behind the punched holes and have the same gloss on the front and back sides.

[0005] Patent Document 3 provides a pressed product that can satisfactorily maintain the firm press-fit state of a shaft pressed into a boss portion. The process includes a primary boss forming step of forming a primary boss having a hole and a protrusion protruding from the periphery of the hole in a portion of a flat plate-shaped material that corresponds to the boss portion, and a boss portion forming step of forming the boss portion by pressing and deforming the protrusion in the protruding length direction.

[0006] In Patent Document 4, in a resin structure formed by laminating multiple base materials made of resin containing reinforcing fibers, the fiber orientation angle around the fastening penetration portion is adjusted in order to suppress the occurrence of interlayer delamination. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] International Publication No. 2017 / 110596 [Patent Document 2] JP 2019-202363 A [Patent Document 3] JP 2006-7253 A [Patent Document 4] JP 2020-203436 A Summary of the Invention [Problem to be solved by the invention]

[0008] However, in the cutting device described in Patent Document 1, holes are made by pushing the composite material apart using a Thomson blade, which makes it difficult to shorten the shortest distance between holes. If an attempt is made to shorten the shortest distance between holes and produce a molded product with multiple holes, cracks may occur on the inner surface of the holes, reducing the strength of the holes and even causing the composite material to break.

[0009] In the invention described in Patent Document 2, the punched plate contains continuous fibers. Therefore, when a plurality of holes are formed in the punched plate, the mechanical strength is extremely weakened depending on the tensile direction.

[0010] Patent Document 3 examines press molding of a rolled steel plate into a shape having a boss, but does not examine at all the use of a composite material containing reinforcing fibers and resin. Also, a protrusion is provided around the hole, but this protrusion is for providing a boss, and the size of the hole is too small. No study has been done at all on a larger hole using a composite material containing reinforcing fibers and resin.

[0011] In Patent Document 4, the study is conducted on the premise that there is only one fastening-through portion. In addition, because the fiber length is too short, no study is conducted on the relationship between the fastening-through portion and the arrangement of the reinforcing fiber. [Means for solving the problem]

[0012] As a result of extensive investigations, the present inventors have found that the above problems can be solved by the means described below, and have arrived at the present invention. 1. A molded article containing discontinuous reinforcing fibers and a resin, The molded product has a plurality of holes h and a base portion, The base part has a hole h i=k and hole h i=k+1 A bridge portion sandwiched between the The bridge portion has the holes h that sandwich the bridge portion. i=k and the hole h i=k+1 and a region in which reinforcing fibers are continuously arranged so as to connect the The area ratio Cf of the cross section of the reinforcing fiber exposed on the inner wall surface C of the hole h is smaller than the fiber volume ratio Vf contained in the entire molded product. Molded products. 2. The base portion has a peripheral portion along the peripheral edge of the hole h, The holes h that sandwich the bridge portion at the peripheral edge i=k and the hole h i=k+1 The ends of the reinforcing fibers arranged to connect the above are oriented toward one side of the molded article, 2. The molded article according to claim 1. 3. The peripheral portion has a protrusion, and the protrusion protrudes toward one surface of the molded article. 3. The molded article according to any one of 1 and 2 above. 4. The molded product according to 3 above, wherein the average thickness t1 of the base portion and the average thickness t2 of the protrusion portions satisfy the relationship t1×1.05≦t2. 5. The molded product described in any one of items 2 to 4 above, wherein the linear expansion coefficient x1 in the thickness direction of the base portion and the linear expansion coefficient x2 in the thickness direction of the peripheral portion satisfy the relationship x1>x2. 6. Said hole h i=k and the hole h i=k+1 6. The molded article according to any one of 1 to 5, wherein the shortest distance between the molded article and the surface of the molded article is 3.0 mm or more and 8.0 mm or less. 7. The molded article according to any one of items 1 to 6 above, wherein the molded article has an isotropic tensile stress at break. 8. The weight average fiber length Lw of the reinforcing fiber is 1 mm or more and 100 mm or less, The molded product includes reinforcing fibers longer than the shortest bridge width of the bridge portion, The resin is a thermoplastic resin. 8. The molded article according to any one of 1 to 7 above. 9. The molded article according to any one of 1 to 8 above, wherein S2>S1. S1: Projected area of ​​the base S2: Hole h represented by the following formula (A) i=k The sum of the projected areas Si of

number

[0013] The molded article of the present invention has the holes h that sandwich the bridge portion. i=k and the hole h i=k+1 and the area ratio Cf of the reinforcing fiber exposed on the inner wall surface C of the hole h when observing the cross section is smaller than the fiber volume ratio Vf contained in the entire molded product. Therefore, compared to a punching plate in which holes are simply punched into a molded product with a drill or the like, the mechanical strength around the holes and the stability of the mechanical strength can be improved. [Brief description of the drawings]

[0014] [Figure 1] FIG. 2 is a schematic diagram showing an example of the molded article of the present invention. [Diagram 2] Schematic showing sampling locations for measuring the degree of two-dimensional random dispersion. [Diagram 3] FIG. 2 is a schematic diagram showing an example of the molded article of the present invention. [Figure 4] (a) is a schematic diagram showing an example of the molded article of the present invention; (b) is a cross-sectional view of the molded article of the present invention; [Diagram 5](a) A schematic diagram showing a state where reinforcing fibers are continuously arranged to connect the hole hi=k and the hole hi=k+1 that sandwich the bridge part. Also, a photograph of the reinforcing fibers present in the bridge part is shown. (b) A schematic diagram showing a state where the end of the reinforcing fiber arranged to connect the hole hi=k and the hole hi=k+1 that sandwich the bridge part in the peripheral part is oriented toward one side of the molded product. [Figure 6] Schematic diagram showing the state in which the end of the reinforcing fiber is stored in the protrusion and the cross section of the fiber is not observed on the peripheral wall surface C. [Figure 7] FIG. 11 is a cross-sectional view showing a state where punching is performed using a conventional technique. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to these.

[0016] [Reinforced fiber] In the present specification, the reinforcing fiber is preferably at least one selected from the group consisting of carbon fiber, aramid fiber, glass fiber, polyester fiber, nylon fiber, polypropylene fiber, and polyethylene fiber. More preferably, the reinforcing fiber is carbon fiber or glass fiber.

[0017] [Reinforced fiber: carbon fiber] 1. Carbon fiber in general When carbon fibers are used, generally known are polyacrylonitrile (PAN)-based carbon fibers, petroleum / coal pitch-based carbon fibers, rayon-based carbon fibers, cellulose-based carbon fibers, lignin-based carbon fibers, and phenol-based carbon fibers, and any of these carbon fibers can be suitably used in the present invention. Among them, polyacrylonitrile (PAN)-based carbon fibers are preferably used in the present invention because of their excellent tensile strength. As the PAN-based carbon fibers, for example, the carbon fiber "Tenax" (registered trademark) STS40-24KS (average fiber diameter 7 μm) manufactured by Teijin Limited can be used.

[0018] 2. Carbon fiber sizing agent The carbon fiber used in the present invention may have a sizing agent attached to its surface. When using carbon fiber with a sizing agent attached, the type of sizing agent can be appropriately selected depending on the type of carbon fiber and the type of resin used in the X material or Y material, and is not particularly limited.

[0019] [Reinforced fiber: glass fiber] The case where the reinforcing fiber used in the present invention is glass fiber will be described. 1. Glass fiber in general The glass fiber used in the present invention may be any glass fiber that is generally called glass fiber. The glass composition is not particularly limited to A-glass, C-glass, E-glass, etc., and may contain TiO2, SO3, P2O5, etc., depending on the case. As the glass fiber, for example, E-glass RS240QR-483 (count: 2400g / 1000m) manufactured by Nitto Boseki Co., Ltd. may be used.

[0020] 2. Glass fiber sizing agent The glass fiber used in the present invention may have a sizing agent attached to its surface. When using glass fiber with a sizing agent attached, the type of sizing agent can be appropriately selected according to the type of glass fiber and the type of resin, and is not particularly limited. The glass fiber can be preferably pretreated with a conventionally known coupling agent such as an organic silane compound, an organic titanium compound, an organic borane compound, and an epoxy compound.

[0021] [Reinforced fibers: Dispersed in the in-plane direction] In the base portion excluding the peripheral portion of the molded article of the present invention, the reinforcing fibers are preferably discontinuous and dispersed in the in-plane direction. In order to disperse the reinforcing fibers in the in-plane direction in the base portion excluding the peripheral portion of the molded article, it is preferable to disperse the reinforcing fibers in the in-plane direction in the composite material.

[0022] "Reinforcing fibers are distributed in the in-plane direction" means that the reinforcing fibers are evenly spread and arranged on a plane. In other words, it means that the fibers are not concentrated in only one direction, but are spread out on a plane. This is expected to improve the strength and rigidity of the material evenly and to distribute stress and load more effectively. More specifically, the reinforcing fibers being dispersed in the in-plane direction preferably means that the fiber axes of the reinforcing fibers form an angle of 45° or less with the in-plane direction.

[0023] 1. In-plane direction The in-plane direction is an arbitrary direction of a parallel plane perpendicular to the plate thickness direction of a composite material or molded product. The composite material is preferably a plate-shaped material. For example, the in-plane direction is the XY direction shown in Figures 1, 2, 3, 4(a), and 5(a) and (b).

[0024] 2. Random distribution in two dimensions The reinforcing fibers dispersed in the in-plane direction are preferably dispersed randomly in the two-dimensional direction. In the region where the composite material is press-molded without flowing, the shape of the reinforcing fibers is almost maintained before and after molding. Therefore, it is preferable that the reinforcing fibers contained in the non-flowing region of the molded product molded from the composite material are also dispersed two-dimensionally randomly in the in-plane direction. In other words, it is preferable that the base part except for the peripheral part of the molded product in the present invention remains in the state of the reinforcing fibers contained in the composite material almost as it is.

[0025] Here, "dispersed two-dimensionally at random" refers to a state in which the reinforcing fibers are oriented randomly in the in-plane direction of the composite material or molded product, rather than in a specific direction such as one direction, and are arranged in the sheet plane without showing a specific direction as a whole. A composite material (or molded product) obtained using discontinuous fibers dispersed two-dimensionally at random is a substantially isotropic composite material (or molded product) that does not have anisotropy in the plane.

[0026] The degree of two-dimensional random orientation is evaluated by determining the ratio of the tensile breaking stress in two mutually perpendicular directions. If the ratio (Eδ) obtained by dividing the larger of the tensile breaking stress values ​​measured in any direction of the composite material (or molded product) by the smaller of the two directions perpendicular to the arbitrary direction is 5 or less, more preferably 2 or less, and even more preferably 1.5 or less, the reinforcing fibers can be evaluated as being two-dimensionally randomly dispersed.

[0027] 3. Tensile breaking stress of molded products In the present invention, the tensile breaking stress of the molded article is preferably isotropic. The isotropy of the tensile breaking stress is evaluated by determining the ratio of the tensile breaking stress in two mutually perpendicular directions. If the (Eδ) ratio, which is the larger of the tensile breaking stress values ​​measured in an arbitrary direction of the molded article and in a direction perpendicular thereto, is divided by the smaller, it can be evaluated that the tensile breaking stress of the molded article is isotropic if it is 5 or less, more preferably 2 or less, and even more preferably 1.5 or less.

[0028] In the molded product of the present invention, since the area of ​​the hole h is large, samples for measuring the tensile breaking stress of the molded product may be taken, for example, as shown in 201 and 202 in Figure 2. This makes it possible to measure the tensile breaking stress in any direction of the molded product and in the direction perpendicular to that direction.

[0029] If the resin contained in the molded product is a thermoplastic resin and the molded product has a three-dimensional shape including curved surfaces, the isotropy of the tensile breaking stress can be evaluated by heating the molded product above its softening temperature, returning it to a flat plate shape, and then solidifying it. Then, by cutting out a test piece and measuring the tensile breaking stress, the degree of isotropy of the tensile breaking stress of the molded product can be confirmed.

[0030] [Reinforcement fiber: fiber length] The molded article of the present invention preferably contains discontinuous reinforcing fibers having a weight average fiber length Lw of 1 mm or more and 100 mm or less. When discontinuous reinforcing fibers are used, the moldability is improved compared to fiber-reinforced plastics using only continuous fibers, and it is easy to create complex molded articles. In addition, by using discontinuous reinforcing fibers, even if stress is applied to the molded article from any direction, it is difficult to find a direction in which the mechanical properties are extremely weakened.

[0031] The weight average fiber length Lw of the reinforcing fiber is more preferably 3 mm or more and 80 mm or less, and even more preferably 5 mm or more and 60 mm or less. If the weight average fiber length Lw of the reinforcing fiber is 100 mm or less, the flowability of the composite material is not likely to decrease when the composite material is produced by press molding, and it is easy to produce the composite material in a desired shape. In addition, if the weight average fiber length Lw is 1 mm or more, the mechanical strength of the obtained fiber-reinforced resin member is not likely to decrease, which is preferable.

[0032] The weight average fiber length Lw and the number average fiber length Ln of the reinforcing fibers can be calculated by the formulas (1) and (2) described below. In addition, in molded articles produced by injection molding, the weight average fiber length of the reinforcing fibers is about 0.1 to 0.3 mm. Therefore, when the weight average fiber length of the reinforcing fibers is set to 1 mm or more and 100 mm or less, it is preferable to produce the molded article by press molding.

[0033] In the present invention, discontinuous reinforcing fibers having different fiber lengths may be used in combination. In other words, the discontinuous reinforcing fibers used in the present invention may have a single peak in the weight average fiber length distribution, or may have multiple peaks.

[0034] [Reinforcing fibers: number average fiber length Ln and weight average fiber length Lw] In general, when the fiber length of each reinforcing fiber is Li, the number average fiber length Ln and the weight average fiber length Lw can be calculated by the following formulas (1) and (2). The units of the number average fiber length Ln and the weight average fiber length Lw are mm. Ln = ΣLi / I Equation (1) Lw = (ΣLi 2) / (ΣLi)...Equation (2) Here, "I" indicates the number of reinforcing fibers measured.

[0035] When the fiber length is constant, the number average fiber length and the weight average fiber length are the same value. Reinforcing fibers can be extracted from molded products, for example, by heating them at 500°C for about 1 hour and removing the resin in a furnace.

[0036] The average fiber length can be calculated, for example, by measuring the fiber lengths of 100 fibers randomly extracted from a molded article to the nearest 1 mm using a caliper or the like, and then calculating the average fiber length based on formula (1). If the fiber contains short fibers that cannot be measured with a caliper, the resin is removed, and the resulting reinforcing fiber is placed in water containing a surfactant and thoroughly stirred with ultrasonic vibration. The stirred dispersion is randomly sampled with a measuring spoon to obtain an evaluation sample, and the lengths of 3,000 fibers are measured using Nireco's Luzex AP image analyzer. Using the measured fiber length, the number average fiber length Ln and weight average fiber length Lw can be calculated in the same manner as in the above formulas (1) and (2).

[0037] [Reinforced fiber: fiber volume ratio] The fiber volume fraction Vf of the reinforcing fibers contained in the molded article is not particularly limited, but is preferably 20 to 70%, more preferably 25 to 60%, and even more preferably 30 to 55%. The fiber volume fraction (Vf unit: volume %) is the ratio of the volume of the reinforcing fibers to the total volume including not only the reinforcing fibers and resin but also other additives.

[0038] Although there is no limitation on the analysis of the reinforcing fiber volume fraction, it is recommended to measure it as follows. A sample is cut out from the molded product, and the resin is burned off in a furnace at 500°C for 1 hour. The mass of the sample is calculated by weighing it before and after the treatment. The volume ratio of the reinforcing fiber, resin, and other additives is then calculated using the specific gravity of each component. Vf = 100 x reinforcing fiber volume / (reinforcing fiber volume + resin volume + other additives volume)

[0039] [resin] The resin contained in the molded article may be either thermosetting or thermoplastic. 1.Thermoplastic resin When the resin used is a thermoplastic resin, the type is not particularly limited, and a resin having a desired softening point or melting point can be appropriately selected and used. As the above-mentioned thermoplastic resin, one having a softening point in the range of 180°C to 350°C is usually used, but is not limited thereto.

[0040] Examples of thermoplastic resins include polyolefin resins, polystyrene resins, polyamide resins, polyester resins, polyacetal resins (polyoxymethylene resins), polycarbonate resins, (meth)acrylic resins, polyarylate resins, polyphenylene ether resins, polyimide resins, polyether nitrile resins, phenoxy resins, polyphenylene sulfide resins, polysulfone resins, polyketone resins, polyether ketone resins, thermoplastic urethane resins, fluorine-based resins, and thermoplastic polybenzimidazole resins.

[0041] The thermoplastic resin used in the molded article of the present invention may be one type or two or more types. Examples of the use of two or more types of thermoplastic resins in combination include, but are not limited to, the use of thermoplastic resins having different softening points or melting points, or the use of thermoplastic resins having different average molecular weights.

[0042] When a thermoplastic resin is used, it is more preferable to use a polyolefin resin, and even more preferable to use a polypropylene resin.

[0043] 2.Thermosetting resin The resin may be a thermosetting resin. When a thermosetting resin is used, it is preferably an unsaturated polyester resin, a vinyl ester resin, an epoxy resin, or a phenol resin. As the resin, one type may be used alone, or two or more types may be used in combination.

[0044] In addition, when a thermosetting resin is used as the resin of the present invention, it is preferable to use a sheet molding compound (sometimes called SMC) containing reinforcing fibers. The high moldability of the sheet molding compound makes it easy to mold even complex shapes. The sheet molding compound has higher fluidity and formability than continuous fibers, making it easy to create ribs and bosses.

[0045] [Other agents] The resin may contain additives such as various fibrous or non-fibrous fillers of organic or inorganic fibers, flame retardants, UV-resistant agents, stabilizers, release agents, pigments, softeners, plasticizers, surfactants, etc., within the scope of the present invention. When a thermosetting resin is used, it may contain thickeners, curing agents, polymerization initiators, polymerization inhibitors, etc. As the additives, one type may be used alone, or two or more types may be used in combination.

[0046] [Molded product: base part] The molded product of the present invention includes a base portion (102). The base portion plays a role of supporting the hole h, providing stability and strength to the molded product. The base portion exemplified by 102 in FIG. 1 forms a flat plate in the molded product, but does not necessarily have to have a flat plate shape and may have ribs or bosses. Even if the hole h is a non-through hole, the base portion does not necessarily include the hole h. If the hole h is a through hole, the base portion does not naturally include the hole h.

[0047] [Molded product: periphery] The peripheral portion refers to the region around the hole h, as exemplified by 103 in FIG. 1 and 502 in FIG. 5(b). The peripheral region is preferably defined as the range from the boundary between the hole h and the base portion toward the base portion, the range being less than the average thickness t1 of the base portion. The peripheral region is more preferably defined as a range from the boundary between the hole h and the base portion toward the base portion, the range being less than 0.8 times the average thickness t1 of the base portion. It is more preferable to define the peripheral region as a range from the boundary between the hole h and the base portion toward the base portion, the range being less than 0.6 times the average thickness t1 of the base portion. It is even more preferable to define the peripheral region as a range from the boundary between the hole h and the base portion toward the base portion that is less than 0.5 times the average thickness t1 of the base portion. In terms of a specific length, the peripheral region is preferably defined as a range of less than 3.0 mm from the boundary between the hole h and the base portion toward the base portion. It is more preferable to define the peripheral region as a range of less than 2.5 mm from the boundary between the hole h and the base portion toward the base portion. It is more preferable to define the peripheral region as a range of less than 2.0 mm from the boundary between the hole h and the base portion toward the base portion. It is even more preferable to define the peripheral region as a range extending from the boundary between the hole h and the base portion toward the base portion, which is less than 1.5 mm inward. It is particularly preferable to define the peripheral region as a range of less than 1.0 mm from the boundary between the hole h and the base portion toward the base portion. The peripheral region is most preferably defined as a range extending from the boundary between the hole h and the base portion toward the base portion, less than 0.5 mm inward. For example, when the hole h is circular, the length indicated by 107 in FIG. 1 can be depicted as the length defined above.

[0048] [Molded product: Protrusion] The peripheral portion has a protrusion, and the protrusion preferably protrudes from one surface of the molded article. The protrusion may be provided on the entire peripheral portion, or may be provided on a part of the peripheral portion. In addition, the protrusion is preferably provided so as to surround the hole h.

[0049] 1. One side Here, "one side" refers to a specific side of the molded product, such as the protrusion 401 in Fig. 4(a). In Fig. 4(a), the one side is the upper side of the paper, which is the negative axis direction of the Z axis depicted in Fig. 4(a). The presence of the protrusion improves the strength of hole h.

[0050] By forming the protrusions, it becomes easier to bend the reinforcing fibers in a stapler shape, making it difficult for the fibers to become shorter and maintaining the strength of the composite material. The presence of the protrusions has effects such as increasing the cross-sectional area of the molded product and improving the load-bearing stress of the bridge portion.

[0051] 2. Thickness in the thickness direction of the plate (thickness in the Z-axis direction in Fig. 4(b)) It is preferable that the average thickness t1 of the base portion and the average thickness t2 of the protrusion satisfy t1×1.05≦t2. Fig. 4(a) and (b) illustrate the average thickness t1 of the base portion and the average thickness t2 of the peripheral wall portion. If t1×1.05≦t2, the presence of the protrusions partially increases the cross-sectional area of the bridge portion and improves the load-bearing stress of the bridge portion.

[0052] More preferably, t1×1.1≦t2≦t1×3.0, and still more preferably, t1×1.5≦t2≦t1×2.0. Specifically, the average thickness t2 of the protrusion is preferably 2.6 mm or more and 10.0 mm or less, more preferably 3.0 mm or more and 10.0 mm or less, still more preferably 3.0 mm or more and 7.0 mm or less, and even more preferably 3.5 mm or more and 5.0 mm or less.

[0053] 3. Thickness of the wall of the protrusion (thickness in the X-axis direction in Fig. 4(b)) When the protrusion is provided so as to surround the hole h, it can be said that the cylindrical molded body is disposed on one side of the molded product. In this case, the thickness W of the wall of the cylindrical protrusion is preferably 0.5 mm≦W<t1 with respect to the average thickness t1 of the base portion, more preferably 0.75 mm≦W<t1×0.8, still more preferably 1.0 mm≦W≦t1×0.6, and even more preferably 1.0×t1≦W≦t1×0.5. The thickness W of the wall of the protrusion can be exemplified by (r2 - r1) / 2 in Fig. 4(b). When the protrusion has a cylindrical shape, r2 is the outer diameter of the protrusion and r1 is the inner diameter of the protrusion.

[0054] [Removal of the protrusion] In the present invention, the molded article may be obtained by cutting off the protrusions formed during molding through secondary processing.

[0055] [Molded product: hole h] The molded article of the present invention contains discontinuous reinforcing fibers and a resin, and has a plurality of pores h. 1. Hole h The molded article of the present invention has a plurality of holes h. Figure 1 shows an example of the molded article of the present invention, and a plurality of holes h (for example, 101 in Figure 1) are provided in the molded article. Also, count adjacent holes from hole h at the edge of the molded product, with i = 1, 2, 3...k...n, and call any hole h i=k In other words, hole h i=k And, hole h i=k+1 The holes are adjacent to each other. i=1 , hole h i=2 , hole h i=3 Here is an example: Hole h i=k And, hole h k+1 The shortest distance between the hole h and the hole h is preferably 3.0 mm or more and 8.0 mm or less, and more preferably 4.0 mm or more and 7.0 mm or less. i=k And, hole h i=k+1 The shortest distance to is illustrated by 104 in FIG.

[0056] 2. Hole h arrangement Although there is no particular limitation on the arrangement of the multiple holes h, it is more preferable that the holes h are circular and that one hole h is surrounded by six holes h. It is more preferable that the holes h are arranged in a honeycomb arrangement. In this case, for example, the arrangement is as shown in Figure 1 or Figure 3. The honeycomb arrangement can maximize the use of space, and (1) since each hole h shares a base with the adjacent hole h through a bridge, more holes h can be arranged in the same area compared to other shapes. (2) In addition, the honeycomb arrangement provides even force distribution and strength. This shape has many connection points between the holes h and has structural stability. (3) Furthermore, the honeycomb arrangement creates the maximum space with the minimum material, so the efficiency of material use is very high. (4) Finally, the honeycomb arrangement promotes air circulation and provides a cooling effect. Air passing through the holes h distributes heat evenly, which helps to regulate the temperature of the holes h.

[0057] 3. Bridge section The molded article of the present invention has a plurality of holes h and a base portion. i=k and hole h i=k+1 The bridge portion is, for example, the black area 105 in FIG. 1, and has a hole h i=k and hole h i=k+1 The bridge portion 105 in FIG. 1 is an example, and the other holes h in FIG. i=k and hole h i=k+1 There is also a bridge portion in the region between the two.

[0058] 4. Hole area In the present invention, it is preferable that S2>S1 is satisfied. S1: Projected area of ​​the base S2: The sum of the projected areas Si of the holes h shown in the following formula (A)

number

[0059] 5. Through and non-through holes of hole h The hole h in the present invention may be a through hole or a non-through hole, and is preferably a through hole.

[0060] 6. Shape of hole h The shape of the hole h is not particularly limited, and may be a circle, an ellipse, a triangle, a quadrangle such as a square or a rectangle, or any of various polygonal shapes, with a circle being preferred.

[0061] [Molded part: Bridge section and reinforced fiber] 1. In the present invention, it is preferable that the molded product contains reinforcing fibers longer than the shortest bridge width of the bridge portion. The bridge width of the bridge portion is shown, for example, at 106 in FIG. 1. An example of the bridge width is shown at 106 in FIG. 1, but the hole h i=k and hole h i=k+1 The shortest distance between the bridge and the hole h corresponds to 104 in FIG. 1. The molded product contains reinforcing fibers longer than the shortest width of the bridge of the bridge, so that the bridge can be reliably reinforced with fibers. i=k and the hole h i=k+1 In other words, the holes h that sandwich the bridge portion can have a region in which the reinforcing fibers are continuously arranged so as to connect the i=k and hole h i=k+1 It can be said that the reinforcing fibers are arranged continuously to bridge the gap between the bridge and the hole. i=k and hole h i=k+1 The state in which the reinforcing fibers are continuously arranged so as to connect the above is shown in 501 of Fig. 5(a). In addition, a photograph of the reinforcing fibers continuously arranged is shown as an enlarged portion of the bridge portion of Fig. 5(a).

[0062] 2. In the molded product of the present invention, the area ratio Cf of the reinforcing fiber exposed on the inner wall surface C of the hole h is smaller than the fiber volume ratio Vf of the entire molded product when observing the cross section. The inner wall surface C is shown in FIG. 5(a).

[0063] In conventional methods (e.g., the methods described in Patent Document 2 and JP 2019-202363 A), when punching is used to make holes in a composite material, fiber cross sections are observed on the inner wall surface of the hole, and the area ratio of the cross sections corresponds to the fiber volume ratio. When a conventional punching process is performed using a composite material in which discontinuous reinforcing fibers are dispersed, the fiber length around the hole becomes shorter, and the strength around the hole decreases.

[0064] On the other hand, the value of the area ratio Cf when observing the cross section of the reinforcing fiber exposed on the inner wall surface C of the hole h of the present invention is smaller than the value of the fiber volume ratio Vf contained in the entire molded product, which means that the fiber cross section observed on the inner wall surface C is smaller than that observed when observing a hole formed by a conventional punching process. This is because the fibers are not cut halfway, and the fiber ends are bent along the inner wall surface. As a result, the value of the area ratio Cf when observing the cross section of the reinforcing fiber exposed on the inner wall surface C of the hole h can be made smaller than the value of the fiber volume ratio Vf contained in the entire molded product. When forming a hole, the strength around the hole can be improved by bending the fibers without cutting them as much as possible.

[0065] There is no particular limitation on the area ratio Cf, but it is preferably 10% or more and less than 60%, more preferably 15% or more and less than 50%, and even more preferably 20% or more and less than 45%. The area ratio (Cf unit: area%) is the ratio of the area of ​​the reinforcing fibers to the total area including not only the reinforcing fibers and resin but also other additives, and is expressed by the following formula. Although there is no limitation on the analysis of the reinforcing fiber volume fraction, it is recommended to measure it as follows. Cf = 100 x reinforcing fiber volume / (reinforcing fiber area + resin area + area of ​​other additives)

[0066] 3. The base portion has a peripheral portion along the periphery of the hole h, and the peripheral portion sandwiches the bridge portion between the hole h.i=k and the hole h i=k+1 It is preferable that the ends of the reinforcing fibers arranged to connect the above-mentioned reinforcement fibers include those oriented toward one surface side of the molded article. Here, "one side" refers to a specific surface of the molded article. In other words, in the base portion excluding the peripheral portion, the reinforcing fibers are randomly dispersed in the in-plane direction, but it is preferable that the ends of the reinforcing fibers present in the peripheral portion are oriented toward one surface of the molded article. In other words, it is more preferable that the ends of the reinforcing fibers randomly dispersed in the in-plane direction are bent and oriented toward one surface of the molded article.

[0067] For example, 502 in Fig. 5(b) is the peripheral portion, and in the peripheral portion depicted in Fig. 5(b), the ends of the reinforcing fibers are depicted as being oriented on one side (503 in Fig. 5(b)). Here, there is a central portion of the fiber where the reinforcing fibers are arranged to connect holes hi=k and hi=k+1 that sandwich the bridge portion, and an end portion of the reinforcing fibers oriented on one side. This shape is similar to that of a staple core, with two fiber ends paired at the tip of the fiber, which are formed by bending from the central portion of the fiber. In Figures 5(a) and (b), the one surface side is the lower side of the paper, and is the negative axis direction of the Z axis direction depicted in Figures 5(a) and (b).

[0068] 4. At the periphery, the holes h that sandwich the bridge portion i=k and the hole h i=k+1 By orienting the ends of the reinforcing fibers arranged to connect the above toward one side of the molded article, the following effects can be achieved. (i) The fiber length of the reinforcing fiber can be maintained long. This is because the fibers in the peripheral portion are bent toward one side, so even if holes h are provided, the fibers are not cut in the middle and the fiber length is maintained. In this case, if a protrusion is provided on the peripheral portion, the long fibers can be stored sufficiently. (ii) Since the fiber cross section is not observed on the inner wall surface C, there is no interface between the resin and the fiber on the inner wall surface C. Therefore, cracks originating from the interface are less likely to occur, and the strength of the hole h is improved. (iii) Since the fiber cross section cannot be observed on the inner wall surface C, even if a person touches it, he or she is unlikely to get injured. In other words, it is preferable that the outermost layer of the inner wall surface C is covered with resin. This resin layer is extremely thin, but even if the hole is touched, the fibers will not come into direct contact with the surface. In order to cover the outermost layer of the inner wall surface C with resin in this way, it is preferable to form the inner wall surface C by a molding process (rather than cutting with a drill). Note that if the inner wall surface C is formed by a molding process, no burrs will be formed on the inner wall surface C, but if a protrusion is provided, a burr will be formed at the tip of the protrusion.

[0069] [Molded product: Orientation and protrusion of reinforcing fiber ends on one side] 1. The base portion has a peripheral portion along the periphery of the hole h, and the peripheral portion has the hole h that sandwiches the bridge portion. i=k and the hole h i=k+1 It is preferable that the ends of the reinforcing fibers arranged to connect the above are oriented toward one surface side of the molded article, and that the peripheral portion has a protrusion, and the protrusion protrudes toward the above one surface side of the molded article. In other words, it is preferable that the bending orientation direction of the ends of the reinforcing fibers and the protrusion direction are oriented in the same direction. Furthermore, it is preferable that the ends of the reinforcing fibers are stored in the protrusions. This stabilizes the strength around the hole. For example, Figure 6 shows a state in which the ends of the reinforcing fibers are stored in the protrusions and the cross section of the fibers is not observed on the peripheral wall surface C.

[0070] [Molded product: Linear expansion coefficient] The linear expansion coefficient x1 in the thickness direction of the base portion and the linear expansion coefficient x2 in the thickness direction of the peripheral portion are preferably x1>x2. Even if the reinforcing fibers are randomly dispersed in the in-plane direction in the base portion excluding the peripheral portion, the ends of the reinforcing fibers present in the peripheral portion are oriented toward one surface of the molded article, so that x1>x2 can be easily satisfied.

[0071] [Integral molding] The molded product of the present invention is preferably an integrally molded product containing reinforcing fibers and resin. Integral molding means that these are molded continuously without any seams and are not molded by joining separate members together. Such integral molding is achieved by creating a structure in one molding operation, preferably by press molding. Since it is created by integral molding, separate parts can be processed as one part, making it possible to reduce the unit price of the part. In addition, the number of assembly steps is reduced, and the reduction in the number of parts also makes it possible to reduce inventory costs.

[0072] [Method of manufacturing molded products: Press molding] 1. Hot press molding and cold press molding When producing the molded article of the present invention, the composite material can be produced by a press molding method (also called compression molding), and as the press molding, a molding method such as hot press molding or cold press molding can be used. By press molding the composite material, various shapes can be given to the molded article.

[0073] 2.Cold press molding When a thermoplastic resin is used as the resin, press molding using a cold press is preferable. In the cold press molding method, for example, a composite material heated to a first predetermined temperature is placed in a mold set to a second predetermined temperature, and then pressurized and cooled.

[0074] Specifically, when the thermoplastic resin contained in the composite material is crystalline, the first predetermined temperature is equal to or higher than the melting point, and the second predetermined temperature is lower than the melting point. When the thermoplastic resin is amorphous, the first predetermined temperature is equal to or higher than the glass transition temperature, and the second predetermined temperature is lower than the glass transition temperature. That is, the cold press method includes at least the following steps A-1) to A-2). Step A-1) A step of heating the thermoplastic resin to a temperature above the melting point and below the decomposition temperature if the thermoplastic resin is crystalline, or to a temperature above the glass transition temperature and below the decomposition temperature if the thermoplastic resin is amorphous. Step A-2) The composite material heated in step A-1) is placed in a mold whose temperature is adjusted to below the melting point if the thermoplastic resin is crystalline, or below the glass transition temperature if the thermoplastic resin is amorphous, and then pressurized. By carrying out these steps, the molding of the composite material can be completed (a press-molded product can be produced).

[0075] The above steps must be performed in the above order, but other steps may be included between each step, such as a shaping step in which, prior to step A-2), a molding die different from the molding die used in step A-2 is used to pre-shape the mold into the shape of the cavity of the molding die. The shape of the composite material may be a shape developed by computer through inverse molding analysis from the three-dimensional shape of the press-molded product to be manufactured.

[0076] 3.Hot press molding In the hot press molding method, for example, a composite material is placed in a mold, pressure is applied while the temperature of the mold is increased to a first predetermined temperature, and the mold is cooled to a second predetermined temperature. Specifically, when the thermoplastic resin constituting the composite material is crystalline, the first predetermined temperature is equal to or higher than the melting point, and the second predetermined temperature is lower than the melting point. When the thermoplastic resin contained in the composite material is amorphous, the first predetermined temperature is equal to or higher than the glass transition temperature, and the second predetermined temperature is lower than the glass transition temperature. The hot press molding preferably includes at least the following steps B-1) to B-4). B-1) A process of placing the composite material in the mold (second mold, lower mold). B-2) A process of applying pressure while heating the mold to a temperature above the melting point and below the thermal decomposition temperature of the thermoplastic resin if the thermoplastic resin is crystalline, or to a temperature above the glass transition temperature and below the thermal decomposition temperature of the thermoplastic resin if the thermoplastic resin is amorphous (first pressing process). B-3) A process of applying pressure in one or more stages so that the pressure in the final stage is 1.2 to 100 times the pressure in the first press process (second press process). B-4) A process for adjusting the mold temperature to below the melting point if the thermoplastic resin is crystalline, or below the glass transition temperature if the thermoplastic resin is amorphous. By carrying out these steps, an integrally molded structure can be produced.

[0077] 4. Commonalities between cold press molding and hot press molding Steps A-2) and B-3) are steps for applying pressure to a composite material to obtain a molded product of a desired shape. The molding pressure at this time is not particularly limited, but is preferably as low as possible within a range in which a desired structure shape can be obtained. Specifically, the molding pressure is preferably less than 30 MPa relative to the mold cavity projected area, more preferably 20 MPa or less, and even more preferably 10 MPa or less. When the molding pressure is less than 30 MPa, it is preferable because it does not require capital investment or maintenance costs for a press machine. In addition, it is natural that various processes may be inserted between the above-mentioned processes during compression molding, and for example, vacuum compression molding in which compression molding is performed while being evacuated may be used.

[0078] [Manufacturing method of hole h] Although there is no particular limitation on the manufacturing method of the molded product of the present invention, an example of the manufacturing embodiment is shown below. When upper and lower molds are used as the molding dies, it is preferable that the first molding die is the upper mold (movable mold) and the second molding die is the lower mold (fixed mold).

[0079] [Manufacturing method of hole h: Manufacturing embodiment 1-1: Bending the composite material] The molded product of the present invention is prepared by preparing a flat composite material containing reinforcing fibers and resin, and press-molding the composite material using a first molding die and a second molding die, thereby pressing and deforming the composite material, and observing the cross section of the reinforcing fibers exposed on the inner wall surface C of the hole h, so that the area ratio Cf can be made smaller than the fiber volume ratio Vf contained in the entire molded product.

[0080] More specifically, a mold is prepared in which a second mold (e.g., a fixed mold) is provided with a plurality of recesses, and a first mold (e.g., a movable mold) is provided with a plurality of protrusions, each of which is a pair of male and female protrusions. When a flat composite material containing reinforcing fibers and resin is placed on this second mold after being heated to a temperature equal to or higher than the softening temperature of the resin and pressed, the composite material is bent to provide recesses in the molded product, and a molded product in which holes h are formed by these recesses can be obtained. At this time, the holes h are non-through. It is preferable to apply a molding pressure of 20 MPa or more.

[0081] [Manufacturing method of hole h: Manufacturing embodiment 1-2: Cutting after bending the composite material] By subjecting the recesses of the molded product produced in the above "Manufacturing embodiment 1-1" to secondary processing using a drill or the like to form through holes, a molded product having hole h penetrating therethrough can be produced.

[0082] [Manufacturing method of hole h: Manufacturing embodiment 1-3: Bending the composite material after drilling a precursor hole] The molded product in the present invention may be prepared by preparing a flat composite material containing reinforcing fibers and a resin, forming a plurality of pre-holes in the composite material, and then bending the composite material as described in "Manufacturing embodiment 1-1" so as to widen the pre-holes and form holes h. It is preferable that two or more pre-holes are formed at the same time by punching, and the punching is repeated two or more times.

[0083] The size of the precursor hole is preferably smaller than the hole h of the molded product. If the precursor hole is designed to be smaller than the hole h of the molded product and the composite material is folded and molded so as to form the hole h during molding, the hole h that sandwiches the bridge portion can be easily formed in the peripheral portion. i=k and the hole h i=k+1 The ends of the reinforcing fibers arranged to connect the above can be oriented toward one side of the molded article.

[0084] [Manufacturing method of hole h: Manufacturing embodiment 2: Flowing the composite material] In the present invention, the molded product is preferably prepared by preparing a flat composite material containing reinforcing fibers and a resin, forming a plurality of pre-holes in the composite material, heating the composite material to a temperature equal to or higher than the softening point of the resin contained in the composite material, and then press-molding the composite material using a first mold and a second mold to press and deform the pre-holes formed in the composite material to form the holes h. The pre-holes refer to holes used in the manufacturing process of the molded product and are holes for forming holes h. It is preferable that two or more pre-holes are formed at the same time by a punching process, and the punching process is repeated two or more times.

[0085] The size of the precursor hole is preferably larger than the hole h of the molded product. If the precursor hole is designed to be larger than the hole h of the molded product and the composite material is flowed and molded so as to form the hole h during molding, the hole h that sandwiches the bridge portion can be easily formed in the peripheral portion. i=k and the hole h i=k+1 The end of the reinforcing fiber arranged to connect the two can be oriented toward one side of the molded article. In other words, this is a method of manufacturing a molded article by flowing the composite material around the precursor hole into the cavity of the mold.

[0086] More specifically, a mold is prepared in which a plurality of recesses are provided in a second mold (e.g., a fixed mold) and a plurality of protrusions are provided in a first mold (e.g., a movable mold) so that they form a pair of male and female protrusions. After heating a flat composite material containing reinforcing fibers and resin to a temperature equal to or higher than the softening temperature of the resin, the precursor holes are arranged to match the recesses in the second mold and pressed, whereby recesses are provided in the molded product, and a molded product in which holes h are formed by the recesses can be obtained. At this time, the holes h are penetrating. It is preferable to apply a molding pressure of 20 MPa or more.

[0087] As a specific size, for example, if the recess provided in the first mold is circular with a diameter of 44 mm, it is preferable to prepare a pair of male and female molds so that the protrusion provided in the second mold (e.g., the movable mold) has a diameter of 42 mm. In this case, it is preferable to provide a precursor hole with a diameter of more than 42 mm in the flat composite material, and it is more preferable to provide a circular precursor hole with a diameter of more than 42 mm and not more than 46 mm.

[0088] [Manufacturing method of hole h: Manufacturing embodiment 3] In the molded product of the present invention, it is preferable to prepare a flat composite material containing reinforcing fibers and a resin, provide a plurality of precursor holes in the composite material, and then form the holes h successively by a roll. EXAMPLES

[0089] 1. Evaluation (1) Material Polypropylene resin: Novatec PP BC03C manufactured by Japan Polypropylene Corporation (sometimes abbreviated as PP) A glass fiber E-glass RS240QR-483 manufactured by Nitto Boseki Co., Ltd. was prepared with a sizing agent attached (sometimes abbreviated as GF).

[0090] (2) Evaluation method Tensile Test Samples were taken from the molded product as shown in 201 and 202 in Figure 2, and tensile tests were performed in any direction of the molded product and in the direction perpendicular to that direction. The tensile conditions were in accordance with ASTM D3039, and a universal testing machine was used to perform a 0° directional tensile test at a test speed of 2 mm / min, and the tensile breaking stress of the sample was calculated. The measurement was performed three times, and the lowest value is listed in Table 1 as the tensile breaking stress.

[0091] (3) Observation of fiber orientation The area around the hole of the molded product was cut out to prepare a 100mm x 100mm sample. The sample was heated to 500℃ in an electric furnace (FP410 manufactured by Yamato Scientific Co., Ltd.) for 1 hour in air to burn off organic matter such as the matrix resin. The fiber orientation was observed.

[0092] (4) The area ratio Cf of the cross section of the reinforcing fiber exposed on the inner wall surface C of the hole h The inner wall surface of the molded product is observed under an optical microscope, 10 areas of 0.1 mm x 0.1 mm are randomly selected, and the area ratio of the cross-section of the reinforcing fiber contained within that range is measured. The average value of the area ratios of the cross-sections of the reinforcing fibers selected at the 10 selected points is taken as the area ratio Cf.

[0093] (5) Fiber volume fraction Vf in the entire molded product The molded product was placed in a furnace at 500°C for 1 hour to burn off the thermoplastic resin, and the mass of the reinforcing fiber and resin were calculated by weighing the mass of the sample before and after the treatment. Next, the volume ratio of the reinforcing fiber and resin was calculated using the specific gravity of each component. Note that the amount of other additives was very small, so they could be ignored in terms of volume. Vf = 100 x reinforcing fiber volume / (reinforcing fiber volume + resin volume + other additives volume)

[0094] [Example 1] (1) Preparation of composite material As the glass fiber, E-glass RS240QR-483 glass fiber manufactured by Nitto Boseki Co., Ltd. was cut to a fiber length of 20 mm, and as the resin, polypropylene resin Novatec PP BC03C manufactured by Japan Polypropylene Corporation was used, and a composite composition of glass fiber and polypropylene resin in which the glass fibers were oriented two-dimensionally randomly was prepared based on the method described in U.S. Patent No. 10006677. The obtained composite composition was heated at 2.0 MPa for 5 minutes in a press machine heated to 250°C, and a flat plate-shaped composite material with an average thickness of 3 mm and dimensions of 600 mm x 1000 mm was prepared.

[0095] (2) Creating a molded product with hole h A molded product was produced using the above-mentioned [Manufacturing embodiment 1-2]. Specifically, the process is as follows. (2-1) Press molding A mold was prepared as follows: · First molding die: A movable die having a cylindrical protrusion with a diameter of 42 mm. · The second molding die: A fixed die with a recess provided so as to form a male-female pair with the first molding die, and the inside of the recess was circular with a diameter of 44 mm. The flat composite material thus prepared was heated above the softening point of the resin to soften it, and then placed in a second mold and press-molded at a pressure of 20 MPa to bend the composite material and create a non-through recess.

[0096] (2-2) Processing with an end mill A through hole was drilled at the bottom of the recess (non-through) of the molded product obtained in (2-1) using an end mill. The molded product obtained was as shown in Figure 4 (a) (b). The dimensions are as follows: Base plate thickness t1: 2.6mm Average thickness of protrusion t2: 5.0mm r1: diameter of hole h (inner diameter of protrusion): 42 mm r2: External diameter of protrusion (cylindrical shape): 44 mm

[0097] [Comparative Example 1] Holes were formed by cutting (with an end mill) in the composite material produced in Example 1. The results are shown in Table 1.

[0098] [Comparative Example 2] A punching plate was used to make holes in the composite material produced in Example 1. The results are shown in Table 1.

[0099] [Table 1] [Explanation of symbols]

[0100] 101: Hole h 102: Base section 103: Periphery 104: Shortest distance between hole h and hole h2 105: Bridge section 106:Bridge width 107: Peripheral area width 201: Cutting out a sample of the molded product to measure the degree of two-dimensional random orientation 202: Cutting out a sample of the molded product in a direction perpendicular to the sample in 201 401:Protrusion t1: Average thickness of the base t2: Average thickness of the protrusion r1: inner diameter of protrusion r2: Outer diameter of protrusion 501: Reinforcement fibers are arranged continuously 502: Periphery 503: End of reinforcing fiber oriented on one side C: Inner wall surface

Claims

1. A molded article comprising discontinuous reinforcing fibers and a resin, The molded product has a plurality of holes h and a base portion, The base part has a hole ｉ＝ｋ and hole h ｉ＝ｋ＋１ A bridge portion sandwiched between the The bridge portion has the hole h that sandwiches the bridge portion. ｉ＝ｋ and the hole h ｉ＝ｋ＋１ and a region in which reinforcing fibers are continuously arranged so as to connect the The area ratio Cf of the cross section of the reinforcing fiber exposed on the inner wall surface C of the hole h is smaller than the fiber volume ratio Vf contained in the entire molded product. Molded products.

2. The base portion has a peripheral edge portion along the peripheral edge of the hole h, The hole h that sandwiches the bridge portion at the peripheral portion ｉ＝ｋ and the hole h ｉ＝ｋ＋１ The ends of the reinforcing fibers arranged to connect the above are oriented toward one side of the molded article, The molded article according to claim 1.

3. The peripheral portion has a protrusion, and the protrusion protrudes toward one surface side of the molded article. The molded article according to claim 1 or 2.

4. The molded product according to claim 3 , wherein an average thickness t1 of the base portion and an average thickness t2 of the protrusion portions satisfy t1×1.05≦t2.

5. The molded product according to claim 2 , wherein a linear expansion coefficient x1 in the thickness direction of the base portion and a linear expansion coefficient x2 in the thickness direction of the peripheral portion satisfy a relationship x1>x2.

6. The hole h ｉ＝ｋ and the hole h ｉ＝ｋ＋１ The molded article according to claim 1 , wherein the shortest distance between the molded article and the surface of the molded article is 3.0 mm or more and 8.0 mm or less.

7. The molded article according to claim 1 , wherein the molded article exhibits isotropic tensile stress at break.

8. The weight average fiber length Lw of the reinforcing fibers is 1 mm or more and 100 mm or less, The molded product includes reinforcing fibers longer than the shortest bridge width of the bridge portion, The resin is a thermoplastic resin. The molded article according to any one of claims 1 to 7.

9. The molded article according to any one of claims 1 to 8, wherein S2>S1. S1: Projected area of ​​the base S2: Hole h represented by the following formula (A) ｉ＝ｋ The sum of the projected areas Si [0010]

10. The molded product according to claim 1 , wherein the holes h are arranged in a honeycomb configuration.

11. A method for producing a molded article according to any one of claims 1 to 10, comprising the steps of: A flat composite material containing reinforcing fibers and a resin is press-molded using a first mold and a second mold to press-deform the composite material, and then The composite material is punched by the first mold to form the hole h. A method for producing a molded article.

12. A method for producing a molded article according to any one of claims 1 to 10, comprising the steps of: The flat-plate-shaped composite material containing reinforcing fibers and a resin is press-molded using a first molding die and a second molding die to press-deform the composite material, and then The mold is removed and secondary processing is performed to form the hole h. A method for producing a molded article.

13. A method for producing a molded article according to any one of claims 1 to 10, comprising the steps of: A flat composite material containing reinforcing fibers and a resin is prepared; After providing a plurality of precursor holes in the composite material, The composite material is press-molded using a first mold and a second mold, thereby pressing and deforming a precursor hole provided in the composite material to form the hole h. A method for producing a molded article.

14. A method for producing the molded article of claim 13, comprising the steps of: Two or more of the precursor holes are simultaneously formed by a punching process, and the punching process is repeated two or more times. A method for producing a molded article.

15. A method for producing a molded article according to any one of claims 1 to 10, comprising the steps of: A flat composite material containing reinforcing fibers and a resin is prepared; After providing a plurality of precursor holes in the composite material, The holes h are continuously formed by a roll. A method for producing a molded article.

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