JP6786826B2 - Fiber reinforced composite and its manufacturing method - Google Patents

Description

The present invention is excellent in appearance and mechanical properties without fiber meandering or unevenness when forming a complicated deep-drawn shape using a sheet-shaped prepreg base material composed of reinforcing fibers aligned in one direction and a thermoplastic resin. The present invention relates to a method for producing a complicated shape deep-drawing molded product and the molded product.

Examples of the method for forming the fiber-reinforced composite include a method of press-molding a fiber-reinforced thermoplastic resin molded plate which is an intermediate base material of the fiber-reinforced composite. An example of the fiber-reinforced thermoplastic resin molded plate is a plate in which a base material impregnated with a thermoplastic resin is laminated on continuous reinforcing fibers called prepregs. The molded product thus obtained has excellent mechanical properties because it uses continuous reinforcing fibers. Further, by arranging the continuous reinforcing fibers regularly, it is possible to design the required mechanical properties, and the variation in the mechanical properties is small.

However, since it is a continuous reinforcing fiber, it is difficult to form a complicated three-dimensional shape, and it is mainly limited to members having a nearly planar shape. Alternatively, when shaping a three-dimensional shape, the prepreg is cut to a width of several mm to form a tape, and by arranging and laminating in the three-dimensional shape, the narrow tape itself only follows the substantially two-dimensional shape. Often, there is a technique called autotape layup that enables shape tracking even for complex shapes.

However, there remains a problem that the productivity is low when used for three-dimensional lamination of a large area and thick member. On the other hand, stamping molding is known as a process having excellent productivity (for example, Patent Document 1). In stamping molding, a heated and melted base material is placed in a mold, the mold is compacted, and then pressure is applied to cool and solidify the molded product. Therefore, the number of steps is small and a large number of molded products can be obtained in a short time. However, there is a problem that wrinkles and bridging (stretching of fibers) due to insufficient deformability of the prepreg occur at the time of shaping, and the yield of the fiber-reinforced composite is lowered.

Since the thickness decreases in the process of solidifying the prepreg laminate to form a fiber-reinforced composite, the prepreg laminate shaped at a portion having a shape change, for example, a corner R portion, has continuous reinforcing fibers having low extensibility. Therefore, in order to eliminate the difference in circumference, buckling occurs and wrinkles occur, or bridging occurs and the mold shape is not followed. In addition, since it is difficult to apply molding pressure directly under bridging, voids are likely to occur. This void generation has been a more prominent problem in low-pressure molding such as oven molding using a vacuum pump as a pressurizing means.

As a fiber-reinforced thermoplastic resin molded plate suitable for molding a complicated shape, a prepreg having a notch penetrating from the front surface to the back surface of the prepreg in a direction crossing the reinforcing fiber of the prepreg is laminated. This base material has the characteristics of achieving both excellent mechanical properties and high formability.

However, when a complex shape is formed using a base material in which a prepreg having a notch as described in Patent Document 2 is laminated, the fibers are twisted when a force is applied in the direction of compression, and the force cannot be transmitted. Therefore, the mechanical properties cannot be exhibited.

Japanese Unexamined Patent Publication No. 2014-156012 Japanese Unexamined Patent Publication No. 2014-173031

An object of the present invention is to shape and mold a two-dimensional sheet-like intermediate base material into a three-dimensional shape having an uneven shape, such as a change in the wall thickness of the uneven portion, surface strength, and member strength such as wrinkles, voids, and fiber meandering inside. It is an object of the present invention to provide a method for producing a fiber-reinforced composite, which has few molding defects causing deterioration, has excellent mechanical properties, and can easily and surely mold a surface grade.

In order to solve the above problems, the present invention employs the following means. That is,
(1) A laminated body of a sheet-shaped prepreg base material composed of reinforcing fibers and a thermoplastic resin, in which at least a part of the reinforcing fibers was divided into lengths of 10 to 100 mm and provided with a plurality of intermittent notches was heated. After that, it is a method of manufacturing a fiber-reinforced composite that pressurizes and cools along a molding die having a three-dimensional curved surface, in which an unmelted portion having a non-heated region around the laminate and a other fused portion are formed. A method for producing a fiber-reinforced composite in which the provided and heated laminate is placed on the molding mold whose temperature is adjusted to be lower than the solidification temperature of the laminate, and the molten portion is placed along the molding mold.
(2) The method for producing a fiber-reinforced composite according to (1), wherein the reinforcing fibers aligned in one direction are used as the sheet-shaped prepreg base material.
( 3 ) The method for producing a fiber-reinforced composite according to ( 1 ), wherein the absolute value of the angle θ (°) formed by the notch and the orientation direction of the reinforcing fibers is in the range of 2 ° to 45 °.
( 4 ) Among the cross-sectional lengths of the fiber-reinforced composite cut in the direction of pressurizing the laminated body, the ratio L1 / L2 of the shortest cross-sectional length L1 and the longest cross-sectional length L2 longer than L1 is 0. The method for producing a fiber-reinforced composite according to any one of (1) to ( 3 ), which is in the range of 3 <L1 / L2 <0.96.
( 5 ) A plurality of bent portions formed in a cross section of the fiber-reinforced composite cut in a direction of pressurizing the laminated body along the reinforcing fiber orientation direction of the laminated body, and the radius of curvature R of the bent portions The fiber-reinforced composite according to any one of (1) to ( 4 ), wherein is in the range of 2 times or more to 5 times or less the thickness d of the fiber-reinforced composite, and has two or more convex portions formed by the bent portions. How to make a body .
It is.

According to the present invention, it has excellent shapeability to a three-dimensional shape, and easily and surely, there are few molding defects that cause a decrease in member strength such as a change in wall thickness of uneven portions and wrinkles, voids, and fiber meandering, and excellent dynamics. It is possible to produce a fiber-reinforced composite having characteristics and surface grade.

It is the schematic which shows an example of the manufacturing method of this invention. It is the schematic which shows an example of the fiber-reinforced composite obtained by the manufacturing method of this invention. It is the schematic which shows the position of the bending part provided in the fiber reinforced composite. It is a partially enlarged view of a bent portion.

The present invention is characterized in that it has excellent shapeability to a complicated shape during stamping molding, can be molded in a short time, and has excellent mechanical properties and surface quality applicable to structural materials. The present invention relates to a method for producing a complex. More specifically, a fiber-reinforced composite that easily follows the molding of a three-dimensional shape such as an R portion or an uneven shape, maintains mechanical strength as a structural member, and is suitably used for, for example, aircraft members, automobile members, sports equipment, and the like. Regarding the manufacturing method of.

More specifically, a laminate obtained by laminating a plurality of prepregs containing unidirectionally oriented reinforcing fibers and a thermoplastic resin is preheated in advance to a temperature equal to or higher than the melting point of the thermoplastic resin to melt the thermoplastic resin and form a cavity. Using a molding mold consisting of an upper mold and a lower mold having an uneven shape, a heated and melted laminate is placed in the mold whose temperature is lower than the solidification temperature of the laminate, and after molding, pressurization and cooling are performed. When performing stamping molding to solidify and obtain a fiber-reinforced composite, when preheating and melting the laminate, a non-heated region is provided in at least a part of the laminate during heating to form an unmelted portion, and the laminate is formed. This is a method for producing a fiber-reinforced composite in which the laminate is pressed against the molding die whose temperature is adjusted to a temperature lower than the solidification temperature of the above, and melted portions other than the unmelted portion are made to follow the molding die.

First, a molding apparatus for producing a fiber-reinforced composite will be described.

As the molding die for molding the fiber-reinforced composite of the present invention, a molding die having a concave portion and a convex portion corresponding to the concave portion and a cavity formed between the concave portion and the convex portion can be used. The thickness of the cavity is preferably 0.5 to 10 mm. Further, among the cross-sectional lengths obtained by cutting the cavity in the direction of pressurizing the laminate, the shortest cross-sectional length L1 measured along the shape of the fiber-reinforced composite and the longest longest cross-sectional length L1 are obtained. It is preferable to use a molding mold in which the ratio L1 / L2 to the length L2 is in the range of 0.3 <L1 / L2 <0.96.

Further, as a jig that can be used when forming a non-heated region when molding the fiber-reinforced composite, a metal frame, a metal film, or a metal tape can be used. Further, when cooling with a refrigerant, air or water having a temperature lower than the resin melting temperature can be used as the cooling medium.

Next, the reinforcing fibers constituting the fiber-reinforced composite used in the present invention will be described.

The type of reinforcing fiber is not particularly limited, and inorganic fiber, organic fiber, metal fiber, or a hybrid-structured reinforcing fiber combining these can be used. Examples of the reinforcing fibers include metal fibers such as aluminum, brass and stainless steel, polyacrylonitrile-based, rayon-based, lignin-based and pitch-based carbon fibers, graphite fibers, insulating fibers such as glass, and aramid resins. Examples thereof include organic fibers such as polybenzoxazole resin, polyphenylene sulfide resin, polyester resin, acrylic resin, nylon resin and polyethylene resin, and inorganic fibers such as silicon carbide and silicon nitride. Further, these fibers may be surface-treated. The surface treatment includes a treatment with a coupling agent, a treatment with a sizing agent, a treatment with an additive, and the like, in addition to a treatment with a metal as a conductor. Further, one type of these reinforcing fibers may be used alone, or two or more types may be used in combination. Among these, carbon fiber is preferable in consideration of mechanical properties such as strength of the final molded product. The average fiber diameter of the reinforcing fibers is preferably 1 to 50 μm, more preferably 5 to 20 μm.

Generally, the longer the length of the reinforcing fibers contained in the laminate, the better the mechanical properties, but the lower the fluidity during stamping molding. In order to improve the fluidity during stamping molding, it is effective to cut the reinforcing fibers to a certain length, which makes it possible to obtain a base material that can flow into a complicated three-dimensional shape such as a rib or a boss. It can reduce wrinkles and bridging. However, it has been difficult to design parts because the base material for stamping molding, which is generally called a random material and is composed of cut reinforcing fibers and a resin composition, has variations in mechanical properties. As a solution to this, by stacking a plurality of prepregs having cuts, it is possible to obtain a laminated body having good mechanical properties and small variations thereof, and excellent fluidity during stamping molding.

The prepreg that can be used in the method for producing a fiber-reinforced composite of the present invention is preferable from the viewpoint of moldability and mechanical properties as long as the fiber volume content Vf is 30% or more and 70% or less. The lower the value of Vf, the better the fluidity, but if the value of Vf is less than 30%, the mechanical properties required for the structural material cannot be obtained. Considering the relationship between fluidity and mechanical properties, 30% or more and 60% or less are preferable. Such a Vf value can be measured based on JIS K7075 (1991).

It is necessary to use a thermoplastic resin as a resin component constituting the fiber-reinforced composite of the present invention. Since the thermoplastic resin can be cooled and solidified without being accompanied by a chemical reaction to obtain a predetermined shape, it can be molded in a short time and is excellent in productivity. Further, by using a thermoplastic resin having a toughness value higher than that of a thermosetting resin in general, strength, particularly impact resistance can be improved. Examples of the thermoplastic resin suitable for the present invention having such characteristics include polyethylene terephthalate (PET) resin, polybutylene terephthalate (PBT) resin, polytrimethylene terephthalate (PTT) resin, and polyethylene naphthalate (PEN) resin. Polyetheretone such as liquid crystal polyester resin, polyolefin such as polyethylene (PE) resin, polypropylene (PP) resin, polybutylene resin, styrene resin, polyoxymethylene (POM) resin, polyamide (PA) resin, polycarbonate ( PC) resin, polymethylene methacrylate (PMMA) resin, polyvinyl chloride (PVC) resin, polyphenylene sulfide (PPS) resin, polyphenylene ether (PPE) resin, modified PPE resin, polyimide (PI) resin, polyamideimide (PAI) resin. , Polyetherimide (PEI) resin, polysulfone (PSU) resin, modified PSU resin, polyethersulfone resin, polyketone (PK) resin, polyetherketone (PEK) resin, polyetheretherketone (PEEK) resin, polyetherketone Fluorine-based resins such as ketone (PEKK) resin, polyarylate (PAR) resin, polyethernitrile (PEN) resin, phenol-based resin, phenoxy resin, polytetrafluoroethylene resin, and polystyrene-based resin, polyolefin-based resin, and polyurethane-based resin. Thermoplastic elastomers such as resins, polyester-based resins, polyamide-based resins, polybutadiene-based resins, polyisopropylene-based resins, and fluorine-based resins, copolymers, modified products, and resins blended with two or more of these. May be good. In particular, PPS resin is used from the viewpoint of heat resistance and chemical resistance, polycarbonate resin and styrene resin are used from the viewpoint of molded product appearance and dimensional stability, and polyamide resin is used from the viewpoint of molded product strength and impact resistance. More preferably used. In addition, flame retardants, weather resistance improvers, other antioxidants, heat stabilizers, UV absorbers, plasticizers, lubricants, colorants, compatibilizers, conductive fillers, etc., depending on the required characteristics of the molded product to be obtained. Can also be added.

When the prepreg that can be used in the method for producing a fiber-reinforced composite of the present invention has a notch, the strength tends to decrease as the thickness of the divided prepreg increases. Assuming that it is applied to a structural material, the thickness of the prepreg is preferably 500 μm or less. On the other hand, if the thickness is less than 50 μm, it is difficult to handle the prepreg, and the number of prepregs to be laminated to form a laminated body becomes very large, so that the productivity is significantly deteriorated. Therefore, from the viewpoint of productivity, it is preferably 50 μm or more and 300 μm or less.

When high fluidity during stamping molding is required, it is preferable to use a prepreg having a notch penetrating from the front surface to the back surface of the prepreg in the direction across the reinforcing fiber.

In the present invention, both a prepreg having no notch penetrating from the front surface to the back surface of the prepreg and a prepreg having a notch penetrating from the front surface to the back surface of the prepreg may be used in the same laminate. In particular, when high fluidity during stamping molding is required, it is preferable that the reinforcing fibers are cut by a cut penetrating from the front surface to the back surface of the prepreg. The length of the cut reinforcing fiber is not particularly limited, but is preferably 10 mm or more and 100 mm or less from the viewpoint of mechanical properties and fluidity. In particular, in order to achieve both sufficient mechanical properties and shapeability during stamping molding, 10 mm or more and 50 mm or less is more preferable.

When a prepreg having a notch is used as the prepreg that can be used in the method for producing a fiber-reinforced composite of the present invention, it can be obtained by making a notch using a laser marker, a sample cutting machine, a die, or the like. It is preferable that the cut is made by using a laser marker because it has an effect that a complicated cut such as a curved line or a zigzag line can be processed at high speed, and the cut is made by using a sample cutting machine. It is preferable because it has the effect of being able to process a large-sized prepreg layer of 2 m or more. Further, it is preferable that the cut is made by using a die because it has an effect that processing can be performed at high speed.

When high mechanical properties are required, it is preferable to use a prepreg containing unidirectionally oriented reinforcing fibers and a thermoplastic resin as it is (a prepreg having no notch penetrating from the front surface to the back surface of the prepreg). .. A plurality of these prepregs can be laminated to form a laminated body.
The absolute value of the angle θ (°) formed by the notch and the orientation direction of the reinforcing fibers is preferably in the range of 2 ° to 45 °, and if the absolute value of θ is larger than 45 °, high fluidity can be obtained. The improvement in mechanical properties is small. In particular, when the absolute value of θ is 45 ° or less, the mechanical properties are significantly improved. On the other hand, if the absolute value of θ is smaller than 2 °, sufficient fluidity and mechanical properties can be obtained, but it becomes difficult to make a stable cut. That is, when the notch falls on the fiber, the fiber easily escapes from the blade when making the notch, and in order to make the fiber length L 100 mm or less, the absolute value of θ is more than 2 °. If it is small, at least the shortest distance between the cuts is smaller than 0.9 mm, which makes it difficult to insert the cuts.

In the next step, the direction of the reinforcing fibers of the prepreg without a notch or the prepreg with a notch obtained as described above is unidirectional, pseudo-isotropic, 0 ° / 90 ° alternating lamination, random lamination, etc. To create a laminated body by laminating so as to have a laminated structure of. Only the prepreg without a notch may be used as the prepreg constituting this laminate, only the prepreg with a notch may be used, or both the prepreg without a notch and the prepreg with a notch may be used. You may use it. At this time, for ease of handling, prepregs forming adjacent layers can be laminated by spot welding with an ultrasonic welding machine to form a laminated body.

In the laminate that can be used in the method for producing a fiber-reinforced composite of the present invention, a plurality of prepregs are laminated so that the directions of the reinforcing fibers are pseudo-isotropic, so that the flow anisotropy during pressing is achieved. Is preferable in terms of reducing the size. The laminated structure is a symmetrical stack of four layers of 0 ° / 45 ° / 90 ° / −45 ° n times ([0 ° / 45 ° / 90 ° / −45 °] ns) or 0 ° / 60. It is preferable that it is a pseudo-isotropic represented by a symmetrical stack of three layers of ° / -60 ° repeated n times ([0 ° / 60 ° / -60 °] ns) (n is an integer of 1 or more). Represents, and s represents a symmetrical laminated structure). By making it pseudo-isotropic, it is possible to suppress warpage of the laminated body. Further, when it is formed into a fiber-reinforced composite used as a structural material, it is necessary to withstand loads from multiple directions. From the viewpoint of mechanical properties, it is preferable that the fiber-reinforced composite is laminated in a pseudo isotropic manner so as to withstand general-purpose use.

The laminate that can be used in the method for producing the fiber-reinforced composite of the present invention is laminated in that the prepregs contained in the prepreg in which the direction of the reinforcing fibers is 0 degrees and the prepregs that are 90 degrees are alternately laminated. It is preferable in that it reduces the anisotropy of body strength.

The thickness of the integrated laminate according to the present invention is preferably 0.5 to 10 mm. If it is less than 0.5 mm, the number of laminated prepregs is small, the influence of the overlapping portion of the cut portion becomes large, and it tends to be a starting point of fracture, which is not very preferable. If it is 0.5 mm or more, the number of layers increases, and even if the cuts overlap, it can be supplemented with another layer. If it exceeds 10 mm, the difference in circumference between the inner layer and the outer layer becomes large at the corner radius, bridging may occur on the inner layer side, the notch on the outer layer side may widen, and the opening may be formed, leading to a decrease in strength. ..

Next, the fiber-reinforced composite obtained by the production method described later will be described in detail.

As shown in FIG. 2, the obtained fiber-reinforced composite has the shortest cross-sectional length L1 (202) among the cross-sectional lengths measured along the shape of the fiber-reinforced composite 201 cut in the direction of pressurizing the laminate. ) And the longest cross-sectional length L2 (203) longer than L1, the ratio L1 / L2 is preferably in the range of 0.3 <L1 / L2 <0.96. If it is 0.3 or less, the difference between L1 and L2 becomes large, so that a large tension is applied to L2, so that the notch widens and becomes an opening, which may lead to a decrease in strength. If it is 0.96 or more, the effect of improving moldability by making a notch is not fully utilized, and the efficiency is not good in consideration of the notch insertion process.

Further, as shown in FIG. 3, the fiber-reinforced composite 301 is preferably provided with a plurality of bent portions 302. As shown in FIG. 4, the bent portions 302 and 402 refer to locations having a certain curvature (radius: R). The radius R on the outer edge side of the bent portion 402 is preferably in the range of 2 times or more and 5 times or less the thickness d (403) of the fiber-reinforced composite 401. If it is less than twice, the difference in circumference becomes large, so that the notch may widen and become an opening. If it exceeds 5 times, the effect of improving moldability by making a notch is not fully utilized, and the efficiency is not good in consideration of the notch insertion process.

When two or more convex portions 303 obtained from the adjacent bent portions 302 are included among the plurality of bent portions 302 formed in the fiber reinforced composite 301, the fibers are constrained in the portion between the convex shapes and the convex shapes. Therefore, bridging occurs, but when a laminated body of prepreg having a notch is used, bridging does not occur because the base material is stretched, and it is preferable in that it can be molded neatly.

Further, it is preferable that the ratio S / L of the projected area Smm ² obtained by projecting the fiber-reinforced composite 201 (301, 401) in the vertical direction to the maximum depth L mm is in the range of 50 mm or more and 1240 mm or less. If it is less than 50 mm, the notch may widen and become an opening. If it exceeds 1240 mm, the effect of improving moldability by making a notch is not fully utilized, and the efficiency is not good in consideration of the notch insertion process. Next, a method for producing the fiber-reinforced composite will be described in detail.

As a method for molding the fiber-reinforced composite of the present invention, a sheet-shaped prepreg having no notch penetrating from the front surface to the back surface of the prepreg composed of the reinforcing fiber and the thermoplastic resin or a cutting penetrating from the front surface to the back surface of the prepreg. A plurality of sheets are laminated using a sheet-shaped prepreg having a inclusion, and the laminated body is heated to the melting point of the thermoplastic resin or higher to melt the laminated body, and at least a part of the laminated body is not provided with a non-heated region at the time of heating. This is a manufacturing method for obtaining a fiber-reinforced composite by forming a molten portion, pressurizing and cooling along a molding mold having a three-dimensional curved surface whose temperature is adjusted to be lower than the solidification temperature of the laminate.

Here, the solidification temperature is the crystallization temperature in the case of a crystalline polymer and the glass transition temperature in the case of an amorphous polymer.

The laminate is heated by a heating device exemplified by a far-infrared heater, a heating plate, a high-temperature oven, dielectric heating, high-frequency heating, and the like. The heating time and heating temperature required for heating the material differ depending on the matrix thermoplastic resin used and are not specified, but it is preferable that the material is heated in the range from the melting point of the matrix resin to the decomposition temperature.

As a method for creating a non-heated region, it is effective to prevent heat from being transferred to a portion to be unmelted during heating. For example, when heating with a far-infrared heater, a metal frame or metal film can be placed on the place you want to unmelt, or just by sticking aluminum tape, far-infrared rays do not pass, so it can be unmelted. it can. Alternatively, far infrared rays may not be irradiated only to the portion to be unmelted. Alternatively, only the portion to be unmelted during heating may be cooled. For example, a cooling medium such as air having a temperature lower than the resin melting temperature may be applied only to the portion to be unmelted.

The heat-melted laminate is conveyed into the mold manually or by using a transfer device. The transfer is preferably performed as quickly as possible, and the transfer time of 30 seconds or less is preferable because the matrix temperature at the time of pressing is not cooled.

The pressure applied to the laminate in the pressurization is preferably 0.1 to 10 MPa, more preferably 0.2 to 3 MPa. This pressure is the value obtained by dividing the pressing force by the area of the laminate. Within this range, the thermoplastic resin can be impregnated between the reinforcing fibers contained in the prepreg, which is preferable.

After pressurizing and cooling until the temperature becomes lower than the solidification temperature of the laminate, the fiber-reinforced composite is obtained by raising the mold upper mold and removing the mold. When demolding, a fiber-reinforced composite may be obtained by using an extrusion pin or the like.

Next, examples and comparative examples of the present invention will be described, but the present invention is not limited to these examples. In Table 2, the rows show examples or comparative examples. From the left, the columns show the presence or absence of unmelted parts of the heated laminate, the next row shows the presence or absence of cuts in the heated laminate, and the next row shows the results of evaluating the shapeability, that is, the surface quality of the molded fiber-reinforced composite. Shown. Wrinkles on the flat surface and bridging on the bent part, which is a problem in practical use ×, wrinkles on the flat surface, and bridging on the bent part, but there is no problem in practical use ○, flat surface A level with no wrinkles in the part and no bridging in the R part and no problem in practical use was set as ◎.

(Example 1)
Prepregs used in the present invention is composed of carbon fiber and nylon 6 in TenCate Cetex (registered trademark) of the end portion in the width direction of Cartesian the fiber direction of the TC910 was thermally welded 700mm square size of sheet The unidirectional prepreg base material was used.

The sheet-shaped unidirectional prepreg base material was inserted into a roller cutter having a blade arranged in a cylinder in the fiber direction, and an intermittent linear notch was inserted. When the fiber length is 12 mm and the angle between the notch and the reinforcing fiber is θ, θ is 22 °.

The fiber direction of the sheet-shaped prepreg was set to 0 °, and eight sheet-shaped prepregs were laminated so as to be (0 ° / 45 ° / 90 ° / −45 °) s to obtain a laminated body of the prepreg.

A far-infrared heater was used as a method for preheating and melting the laminate. The laminate was heated with a far-infrared heater until the center temperature of the laminate reached 260 ° C. to obtain a heated laminate. An unmelted portion was produced in the heated laminate by placing an aluminum frame on a portion to be unmelted when the laminate was heated, around the laminate, and a width of 50 mm to provide a non-heated region.

A fiber-reinforced composite was obtained by cold-pressing the heated laminate at a pressure of 3 MPa using a molding die consisting of an upper die and a lower die having an uneven shape in a cavity heated to 150 ° C.

The obtained fiber-reinforced composite had no wrinkles or bridging, and the surface quality was good, and there was no problem in practical use. The evaluation was ⊚.

(Example 2)
Using the prepreg of Example 1, a fiber-reinforced composite was molded in the same manner as in Example 1 without inserting a notch, and the surface quality of the obtained fiber-reinforced composite was evaluated. Although some bridging was observed on the surface of the fiber-reinforced composite, it was at a level where there was no problem in practical use, and the evaluation was evaluated as ◯.

(Comparative Example 1)
Using the prepreg of Example 1, a notch was inserted in the same manner as in Example 1. A fiber-reinforced composite was molded in the same manner as in Example 1 except that an unmelted portion was not provided when the laminate was heated, and the surface quality of the obtained fiber-reinforced composite was evaluated. Wrinkles were seen on the surface of the fiber-reinforced composite, and it was judged that there was a problem in practical use, and the evaluation was evaluated as x.

(Comparative Example 2)
Using the prepreg of Example 1, a fiber-reinforced composite was formed in the same manner as in Example 1 except that an unmelted portion was not provided when the laminate was heated without inserting a notch, and the obtained fiber-reinforced composite was obtained. The surface quality was evaluated. Wrinkles were observed on the surface of the fiber-reinforced composite, and bridging was observed at the corner R portion, which was judged to be a practically problematic level, and the evaluation was evaluated as x.

The present invention can easily follow the molding of a three-dimensional shape such as an R portion or an uneven shape, and can maintain mechanical strength as a structural member. Therefore, the present invention is suitably used for, for example, aircraft members, automobile members, sports equipment, and the like. Can be done.

101: Prepreg 102: Laminated body 103: Metal frame 104: Heater 105: Heated laminated body 106: Heated laminated body molten part 107: Heated laminated body unmelted part 108: Lower mold 109: Upper mold 110, 201, 301, 401: Fiber-reinforced composite 202: The fiber-reinforced composite having the shortest circumference L1 Cross-sectional length of the fiber-reinforced composite cut in the direction of pressurization 203: The fiber-reinforced composite having the longest circumference L2 in the direction of pressurization Cross-sectional length 302, 402: bent portion 303: convex shape portion 403: thickness measurement point of the cut fiber-reinforced composite

Claims (5)

After heating a laminate of sheet-shaped prepreg base material composed of reinforcing fibers and thermoplastic resin and having at least a part of the reinforcing fibers divided into lengths of 10 to 100 mm and provided with a plurality of intermittent notches , the tertiary It is a method of manufacturing a fiber-reinforced composite that pressurizes and cools along a molding die having an original curved surface, in which an unmelted portion having a non-heated region around the laminate and a other fused portion are provided and heated. A method for producing a fiber-reinforced composite in which the laminated body is placed on the molding die whose temperature is adjusted to be lower than the solidification temperature of the laminate, and the molten portion is placed along the molding die. The method for producing a fiber-reinforced composite according to claim 1, wherein the reinforcing fibers aligned in one direction are used as the sheet-shaped prepreg base material. The method for producing a fiber-reinforced composite according to claim 1 , wherein the absolute value of the angle θ (°) formed by the notch and the orientation direction of the reinforcing fibers is in the range of 2 ° to 45 °. Of the cross-sectional lengths of the fiber-reinforced composite cut in the direction of pressurizing the laminate, the ratio L1 / L2 of the shortest cross-sectional length L1 and the longest cross-sectional length L2 longer than L1 is 0.3 <L1. The method for producing a fiber-reinforced composite according to any one of claims 1 to 3 , which has a range of / L2 <0.96. It has a plurality of bent portions formed in the cross section of the fiber-reinforced composite cut in the direction of pressurizing the laminated body along the reinforcing fiber orientation direction of the laminated body, and the radius of curvature R of the bent portion is the fiber. The method for producing a fiber-reinforced composite according to any one of claims 1 to 4 , which is in the range of 2 times or more to 5 times or less the thickness d of the reinforced composite and includes two or more convex portions formed by the bent portions .