JP2016068385A - Method for manufacturing fiber-reinforced plastic - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing an FRP using a RTM method capable of obtaining a molded article of good quality having no air trap, particularly capable of obtaining a molded article having no air trap with a completely-sealed type mold.SOLUTION: The method for manufacturing a fiber-reinforced plastic includes the steps of: placing a preform composed of a reinforcing fiber base material in a cavity of a mold; impregnating the preform with a resin injected from a resin-injection opening provided in the cavity while fluidizing the resin in a direction toward a resin suction opening provided in the cavity; and curing the resin, where the resin injection opening and the resin suction opening are provided in a region at which the preform is placed, and a space-occupying fiber volume content in a predetermined region in the cavity is within a range of ±10 volume% to a space-occupying fiber volume content in a region containing a reference surface determined preliminarily in the cavity.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for manufacturing a fiber reinforced plastic (FRP), and more particularly, to a method for manufacturing a fiber reinforced plastic in which a preform made of a reinforced fiber base material is impregnated with an injection resin by a RTM (Resin Transfer Molding) method. Regarding improvements.

  A preform made of a reinforcing fiber base is placed in the cavity of the mold, and resin is injected from a plurality of resin inlets that open facing one surface of the preform to form a reinforcing fiber base for the preform. An RTM method called so-called RTM multi-point injection method for impregnation is known (for example, Patent Document 1 and Patent Document 2). Also known is an RTM method called a so-called line injection method in which a resin injection line extending along the end surface is provided on the end surface side of the preform, and resin is supplied and injected from the end surface of the preform disposed in the cavity. .

  Compared with the line injection method, the RTM multi-point injection method can spread the resin in all directions from each of a large number of injection points arranged on one surface of the preform. It has the advantage that it can be impregnated with resin. Also, because the injection point is placed on one surface of the preform, race tracking that tends to occur around and inside the preform (resins flowing from different directions regulate the flow and streaks Etc.) is less affected by the unique flow, such as flow front shape (the shape of the tip of the resin flow) according to the resistance of the preform It can be expanded to a flow front shape corresponding to the shape of the inlet (for example, a circular inlet, an equal thickness preform, and a pseudo isotropic laminated preform tend to have a circular flow front shape). However, since it is a method of injecting resin into a closed mold, an air trap may easily occur in the region of the preform to be molded, but a method of assisting resin injection / impregnation by vacuum suction Has also been introduced.

  On the other hand, in the line injection method, since the resin is injected in a specific direction from a predetermined resin injection line, the resin injection speed is relatively easy to control, and the position of the flow front and the progress thereof are easy to monitor. However, if the flow front shape line does not advance in the desired shape or there are places where the flow front is difficult to reach, insufficient impregnated resin parts (resin starve parts or resin non-impregnated parts) are likely to occur, There is a possibility that a part with poor quality is generated.

JP 2010-89501 A International Publication No. 2012/115067

  However, in either the RTM multi-point injection method or the line injection method, race tracking is still likely to occur around the preform edge, and the resin flows first around the outer periphery of the preform, causing air to enter the preform. There remains concern about being trapped. If air is trapped in the preform, a resin starve portion or a resin non-impregnated portion is likely to be generated, and there may be a portion where the surface quality of the obtained fiber reinforced plastic is insufficient.

  For example, the following problems may occur in the RTM multipoint injection method. The flow front shape depending on the resin flow resistance of the preform and the shape of the resin inlet does not necessarily match the shape of the fiber reinforced plastic to be molded. Therefore, an air trap may be caused within the range of the shape of the fiber reinforced plastic due to race tracking or the like. Further, in the method of assisting by vacuum suction, it is often impossible to take a sufficient time to make a complete vacuum state in consideration of the molding cycle time. Therefore, in the case of a particularly large mold (cavity), the molding may be completed in a state where air is finally trapped in the preform. Furthermore, as a method of reducing the air trap, there is a method of sucking and discharging air and resin together (as foamed resin since separation is difficult), but the cleaning of the discharge port is complicated, and another problem is aggravated.

  Therefore, in view of the limitations in the prior art, the object of the present invention is to obtain a molded article of good quality without an air trap in the preform. It is an object of the present invention to provide a method for producing a fiber reinforced plastic using the RTM method, which can obtain a molded product having no shape.

The present invention for solving the above problems employs the following configuration. That is,
(1) A preform made of a reinforcing fiber base is disposed in a cavity of a mold, and resin injected from a resin injection port provided in the cavity is directed to a resin suction port provided in the cavity. In the manufacturing method of the fiber reinforced plastic in which the preform is impregnated while flowing in the direction and the resin is cured, the resin injection port and the resin suction port are provided in a region where the preform is disposed, and the cavity A fiber characterized in that a space occupied fiber volume content in a predetermined region is within a range of ± 10% by volume with respect to a space occupied fiber volume content in a region including a predetermined reference plane in the cavity. A method of manufacturing reinforced plastics.
(2) The method for producing a fiber-reinforced plastic according to claim 1, wherein the space occupied fiber volume content is controlled by at least one of the following methods (a) to (c).
(A) The height of the cavity clearance is enlarged in a predetermined region.
(B) The cavity clearance is lowered in a predetermined region.
(C) The amount of reinforcing fibers used in the preform is controlled in a predetermined region.
(3) The fiber reinforcement according to (2), wherein the height of the cavity clearance in the predetermined region is increased or decreased by 0.5 to 20% with respect to a predetermined reference region. Plastic manufacturing method.
(4) The amount of the reinforcing fiber used in the region having the volume occupied fiber volume content is changed within a range of ± 20% with respect to the amount of the reinforcing fiber in the predetermined reference region. The method for producing a fiber-reinforced plastic according to (2).
(5) The fiber reinforced fiber according to any one of (1) to (4), wherein a space occupied fiber volume content in a region including a predetermined reference plane in the cavity is 30 to 70%. Plastic manufacturing method.
It is.

  According to the present invention, it is possible to obtain a molded article of good quality without an air trap in the preform, and in particular, an RTM method capable of obtaining a molded article without an air trap with a completely sealed mold. It is possible to provide a method for producing a fiber reinforced plastic using

It is a schematic longitudinal cross-sectional view (sectional drawing which follows the A-A 'line of FIG. 4) of the RTM shaping | molding apparatus used in order to implement the method which concerns on the 1st form of this invention. FIG. 2 is a schematic perspective plan view of the inside of the molding die of the apparatus of FIG. 1 as viewed from the upper surface side, and is a view showing a resin flow front when resin injection is started from a resin injection port. It is the schematic which showed how the resin flow front spreads in FIG. FIG. 2 is a schematic perspective plan view of the inside of the mold of the apparatus of FIG. 1 as viewed from the upper surface side. FIG. 5 is a partially enlarged sectional view taken along line B-B ′ of FIG. 4, and is a schematic sectional view when a cavity clearance is enlarged. FIG. 6 is a partial enlarged cross-sectional view taken along line B-B ′ of FIG. 4 according to another embodiment different from FIG. 5, and is a schematic cross-sectional view when the cavity is thinned. FIG. 7 is a partial enlarged cross-sectional view taken along line B-B ′ of FIG. 4 according to another embodiment different from FIGS. 5 and 6, and is a schematic cross-sectional view when a preform is changed by controlling the amount of reinforcing fibers. It is the schematic which showed the resin flow front at the time of improving the resin flow front in FIG. It is the schematic which showed the resin flow front at the time of improving the resin flow front in FIG. FIG. 4 is a schematic perspective plan view of the inside of a molding die of the apparatus according to another embodiment different from FIG. 2 and shows how the resin flow front spreads when resin injection is started from the resin injection port. It is. It is the schematic which showed the resin flow front at the time of improving the resin flow front in FIG.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a schematic view of an RTM molding apparatus 1, and a molding die 3 having a cavity 2 is composed of an upper die 4 and a lower die 5. The RTM molding device 1 has a press mechanism 6 so that the upper die 4 can be clamped and opened. The preform 7 is made of a laminated body of reinforcing fiber bases, and is shaped in advance into a predetermined shape, for example, and disposed in the cavity 2. The preform 7 may be integral or a combination of a plurality of preforms. At least one resin injection path 8 for supplying resin is connected to the mold 3. In the upper mold 4, one or more resin injection ports 9 connected to the resin injection path 8 are provided, and the resin injection ports 9 are opened and closed by, for example, a pin-shaped valve body 10. Further, the mold 3 is provided with a heat medium passage 11 and is heated and cooled by the circulating heat medium.

  For example, when the thermosetting resin is injected, the resin is satisfactorily impregnated, and after the resin impregnation, the resin impregnated and impregnated is heated to cure a predetermined fiber-reinforced plastic molded product. The periphery of the cavity 2 is sealed with a sealing material 12.

  Examples of reinforcing fibers used for the fiber-reinforced base material used in the preform 7 according to the present invention include metal fibers such as aluminum fibers, brass fibers, and stainless fibers, polyacrylonitrile-based, rayon-based, lignin-based, pitch-based, and the like. Carbon fiber, graphite fiber, glass fiber, silicon carbide fiber, silicon nitride fiber and other inorganic fibers, aramid fiber, polyparaphenylene benzobisoxazole (PBO) fiber, polyphenylene sulfide fiber, polyester fiber, acrylic fiber, nylon Organic fibers such as fibers and polyethylene fibers can be used. These reinforcing fibers may be used alone or in combination of two or more. Among these, carbon fiber is preferable from the viewpoint of the balance of specific strength, specific rigidity, and lightness, and at least polyacrylonitrile (PAN) -based carbon fiber is preferably included from the viewpoint of excellent specific strength and specific modulus.

  As the resin used in the present invention, a thermosetting resin or a resin for RIM (resin injection molding) that forms a thermoplastic resin that has a low viscosity and can be easily impregnated into the reinforcing fiber is preferable. Examples of thermosetting resins include epoxy resins, unsaturated polyester resins, vinyl ester resins, phenol resins, guanamine resins, polyimide resins such as bismaleide and triazine resins, furan resins, polyurethane resins, polydiallyl phthalate resins, A melamine resin, a urea resin, an amino resin, etc. are mentioned.

  Also, polyamide resins such as nylon 6 resin, nylon 66 resin, nylon 11 resin, or copolymer polyamide resins of these polyamide resins, polyester resins such as polyethylene terephthalate resin and polybutylene terephthalate resin, or of these polyester resins Copolyester resin, polycarbonate resin, polyamideimide resin, polyphenylene sulfide resin, polyphenylene oxide resin, polysulfone resin, polyethersulfone resin, polyetheretherketone resin, polyetherluimide resin, polyolefin resin, etc. Examples thereof include thermoplastic elastomers typified by polyester elastomer resins and polyamide elastomer resins. Also, a resin obtained by blending a plurality selected from the above-mentioned thermosetting resins, thermoplastic resins, and rubbers can be used.

  Among these, epoxy resins are preferable from the viewpoint of suppressing thermal shrinkage during molding. Generally, as an epoxy resin for composite materials, a bisphenol A type epoxy resin, a phenol novolac type epoxy resin, or a glycidylamine type epoxy resin is used as a main agent. On the other hand, as a curing agent, a curing agent system in which dichlorophenyldimethylurea is combined with dicyandiamide is preferably used in terms of excellent workability and physical properties. However, it is not particularly limited, and diaminodiphenyl sulfone resin, aromatic diamine resin, acid anhydride polyamide resin and the like can also be used. Further, the ratio of the resin and the above-mentioned reinforcing fibers is preferably in the range of 20:80 to 70:30 in terms of weight ratio in order to maintain appropriate rigidity. Among them, epoxy resin or modified epoxy resin blended with thermoplastic resin or rubber component, nylon resin, dicyclopetadiene resin are more suitable from the viewpoint of reducing the thermal shrinkage of fiber reinforced plastic and suppressing the occurrence of cracks. ing.

  The method for producing a fiber reinforced plastic according to the present invention can also be applied to molding a fiber reinforced resin structure having a laminated structure of a fiber reinforced resin and a core material. For example, a sandwich structure in which fiber reinforced resin layers are arranged on both sides of the core material can be exemplified. As the core material, an elastic body, a foam material, and a honeycomb material can be used, and a foam material and a honeycomb material are preferable for weight reduction. The material of the foam material is not particularly limited, and for example, a foam material made of a polymer material such as polyurethane resin, acrylic resin, polystyrene resin, polyimide resin, vinyl chloride resin, or phenol resin can be used. The material of the honeycomb material is not particularly limited, and for example, aluminum alloy, paper, aramid paper, or the like can be used.

  FIG. 2 is a schematic perspective plan view of the inside of the mold of the apparatus of FIG.

  End portions of the resin injection port 9 and the suction port 30 are respectively arranged in the molded product outer shape 20, and an allowable region 40 in which the resin flow front is finally contained is arranged around the suction port 30 as described later. Can be set. In the present invention, the “region” refers to a specific range defined in the schematic perspective plan view of the preform 7 shown in FIG.

  Here, the manufacturing method of the fiber reinforced plastic which concerns on this invention is demonstrated.

  A preform 7 (or a laminate in which reinforcing fiber base materials are laminated) is placed in a cavity 2 provided in the lower mold 5. With the preform 7 placed in the cavity 2, the upper mold 4 is clamped with respect to the lower mold 5, and air is sucked from the suction port 30. When the resin supplied from the resin injection path 8 is injected into the cavity 2 from a plurality of resin injection ports 9 that open to face one surface (upper surface) of the preform 7, the resin injection port 9 shows the state shown in FIG. Thus, the initial flow front 100 is formed. The flow front 100 gradually spreads concentrically and is impregnated throughout the preform 7. The mold 3 is heated or cooled by, for example, a heat medium flowing through the heat medium flow passage 11, and the resin is satisfactorily impregnated when the thermosetting resin is injected. After the resin impregnation, the mold 3 is heated, The resin impregnated and impregnated is cured to produce a predetermined fiber reinforced plastic.

In the present invention, it is desirable to grasp in advance the behavior of the resin by resin flow analysis in advance as to how the resin flows. In the present invention, the space occupied fiber volume content is defined by the following equation.
Vpf = Vp / (l ・ w ・ h)
Vpf (volume%): space occupied fiber volume content, Vp (mm ³ ): preform volume, l (mm): length, w (mm): width, h (mm): cavity thickness

Here, the length and width correspond to the length and width of the region occupying the space occupied fiber volume content. When the area cannot be defined by the above-described length or width, it can be calculated from the area S (mm ² ) and the cavity thickness h (mm) occupied by the area as follows.
Vpf = Vp / (S · h)

  If the above equation is used, the volume content of space occupied fibers can be said to be the volume content of reinforcing fibers in the space taking into account the cavity thickness when a specific region is viewed in the thickness direction. .

  For example, in the case of a uniform space occupied fiber volume content in the shape as shown in FIG. 3, when the resin flow front 101 reaches the suction port 30, Although 101 has not reached, since the flow front 101 has reached a part of the outer shape 20 of the molded product (lower edge in FIG. 3), there is no flow path from the corner to the air suction port 30. Therefore, the air trap 110 is generated because there is no place for air at the corners.

  In order to eliminate such an air trap 110, as a method of controlling the flow of the resin so that the resin flow front finally fits within the allowable area 40, which is an allowable area for production even if an air trap is present, As shown in FIG. 4, it is important to provide a predetermined region 60 different from the space occupied fiber volume content of the reference surface 50 determined in advance in the cavity.

  The predetermined reference surface 50 in the cavity is the largest region where the area where the space occupied fiber volume content is the same in the obtained fiber reinforced plastic is the largest, and the space occupied fiber volume content is 30 to 70 volumes. % Is preferable. When the space occupied fiber volume content exceeds 70% by volume, the resin flow resistance is too high, so that the resin is not sufficiently impregnated in the preform, and an unimpregnated region may be generated. In addition, when the volume content of space-occupied fibers is less than 30% by volume, the amount of reinforcing fibers is small, and thus there is a problem that the reinforcing fiber base material is displaced or deformed due to the resin flow pressure during resin flow. To do. The space occupied fiber volume content is preferably 35 to 65% by volume, more preferably 40 to 60% by volume, and still more preferably 45 to 55% by volume.

  Since the flow resistance of the resin in the predetermined region 60 is different from the flow resistance in the reference surface 50 by setting the space occupied fiber volume content in the predetermined region 60 to be different from that of the reference surface 50, the predetermined region 60 The flow of the resin can be different from that of the reference surface 50. For example, when the space occupied fiber volume content in the predetermined region 60 is smaller than the reference surface 50, the flow resistance decreases in the predetermined region 60 as compared with the reference surface 50, so that the resin flow rate increases and the flow front is increased. The distance is longer than that of the reference plane 50. On the contrary, when the volume occupied fiber volume content of the predetermined region 60 is larger than the reference plane 50, the resin flow resistance increases, so the resin flow rate becomes slow, and the distance to the flow front is compared with the reference plane 50. Become shorter. In determining the location where the predetermined region 60 is to be provided, the resin flow front is predicted in advance, and the space occupied fiber volume content is reduced in a place where the resin is difficult to flow so that the final flow front of the resin is within the allowable region 40. On the contrary, in a place where the resin easily flows, the flow rate of the resin can be suppressed by increasing the volume content of space occupied fiber, and the final flow front can be adjusted to be within the allowable area 40.

  If the space occupied fiber volume content is greatly changed, the physical properties of the predetermined region 60 may be greatly changed as compared with the physical properties of the reference surface 50. Therefore, it is desirable that the space occupied fiber volume content is not greatly changed. On the other hand, if the change in the space occupied fiber volume content is too small compared to the reference surface 50, the resin flow rate cannot be changed. Therefore, it is important that the change in the space occupied fiber volume content is ± 10% by volume or less compared to the reference plane 50. If the change in the space occupied fiber volume content exceeds 10% by volume, the resin flow resistance of the predetermined region 60 becomes too high with respect to the reference surface 50, and a region where the resin is not impregnated with the resin tends to occur. If the change in the space occupied fiber volume content is less than 10% by volume, the resin flow resistance of the predetermined region 60 becomes too low with respect to the reference surface 50, and there is sufficient resin in the region that becomes the reference surface 50. An unimpregnated region is likely to occur without diffusion.

  FIG. 5 is a partially enlarged sectional view taken along line B-B ′ of FIG. 4, and shows a schematic sectional view when the cavity clearance is enlarged. Since the space occupied fiber volume content in the region 70 where the height of the cavity clearance is higher than the reference surface 50 is smaller than the space occupied fiber volume content in the reference surface 50, the resin flow resistance is low. Increases flow rate. As a result, the effect of extending the distance of the flow front can be obtained. Moreover, it also has the effect that the resin diffuses around the enlarged portion 70 as a base point.

  Here, the ratio of increasing the height of the cavity clearance in the enlarged portion 70 with respect to the height of the cavity clearance in the reference surface 50 is desirably 0.5% to 20%. When the cavity is made higher than 20% with respect to the reference plane 50, the surface layer of the fiber reinforced plastic that occupies this region becomes resin-rich, and the occurrence of chipping tends to be fragile. If it is less than 0.5%, the change in the space occupied fiber volume content is too small, so that the desired effect cannot be obtained. The cavity clearance expanding portion 70 may be provided not only in the upper mold 4 but also in the lower mold 5. Further, the cross-sectional shape of the enlarged portion is not limited to a rectangle, but may be a semicircle or a triangle, and is not limited to a specific shape.

  6 is a partially enlarged cross-sectional view taken along the line BB ′ of FIG. 4 according to another embodiment different from FIG. 3, and is a schematic cross-sectional view when the cavity is thinned by reducing the cavity clearance height. . In the region 80 in which the cavity height is made thinner than the reference surface 50, the space occupied fiber volume content of this region is higher than that of the reference surface 50, so that the resin flow resistance is higher and the resin flow rate is higher than that of the reference surface 50. Become slow. As a result, an effect of shortening the distance to the flow front can be obtained.

  The ratio of decreasing the cavity clearance height in the thinned region 80 to the height of the cavity clearance in the reference surface 50 is desirably 0.5% to 20%. When the cavity is made lower than 20% with respect to the reference surface 50, the resin flow resistance in this region becomes too high. Therefore, it becomes easy to generate | occur | produce the area | region which resin does not impregnate in a reinforced fiber. If it is less than 0.5%, the change in the space occupied fiber volume content is too small, so that the desired effect cannot be obtained. The shape for thinning the cavity may be provided not only in the upper mold 4 but also in the lower mold 5. The cross-sectional shape is not limited to a rectangle, and may be a semicircle or a triangle, and is not limited to a specific shape.

  FIG. 7 is a partially enlarged cross-sectional view taken along line BB ′ of FIG. 4 according to another embodiment different from FIGS. 5 and 6, and a cross section when a preform is changed by controlling the amount of reinforcing fibers. A schematic diagram is shown. In FIGS. 5 and 6, the flow resistance of the resin is changed by changing the cavity gap, whereas in FIG. 7, the space occupied fiber volume content of the preform itself is changed. As a method of changing the amount of the reinforcing fiber of the preform, for example, changing the input amount of the same fiber reinforced base material, changing the basis weight of the fiber reinforced base material, changing the weaving method, and changing the volume occupied fiber volume content And so on.

  When the amount of reinforcing fibers is larger than the reference plane 50, the space occupied fiber volume content increases, the resin flow resistance increases, and the resin flow rate becomes slower than the reference plane 50, so the distance to the flow front is the reference plane 50 50 can be shortened. On the other hand, when the amount of reinforcing fibers is smaller than the reference plane 50, the space occupied fiber volume content decreases, the resin flow resistance decreases, the resin flow speed increases compared to the reference plane 50, and the distance to the flow front is the reference. Longer than the surface 50.

  The amount of reinforcing fibers is preferably changed within a range of ± 20% with respect to the amount of reinforcing fibers in a predetermined reference region. When the amount of the reinforcing fiber exceeds 20% from the reference plane 50, the volume occupied fiber volume content becomes too high and the resin flow resistance becomes too high, so that the resin may not be impregnated. On the other hand, when the amount of reinforcing fibers exceeds −20% from the reference plane 50, the space occupied fiber volume content becomes too low, which may cause a decrease in physical properties and a resin-rich portion.

  In the present invention, it is desirable to grasp in advance the behavior of the resin by resin flow analysis in advance. When it is predicted that an air trap or the like is generated in the analysis, it is important to arrange the predetermined region 61 having a low space occupied fiber volume content so as to be a resin flow front that does not generate an air trap.

  Therefore, a predetermined region 61 having a low space occupied fiber volume content can be provided as shown in FIG. In this shape, by reducing the volume content of space occupied fiber in the area, the flow front is changed to 102, a flow path to the air suction port 30 is secured, and the air trap as shown in FIG. 110 does not occur, and the occurrence of air traps is improved. Alternatively, as shown in FIG. 9, by providing a predetermined region 62 having a high space occupied fiber volume content and changing the flow front as 103, a flow path to the air suction port 30 is secured, and an air trap is generated. It is also preferable to improve.

  Moreover, the shape shown in FIG. 10 can be illustrated as an aspect different from FIG. In this case, when the resin flow front 103 reaches the suction port 30, it has not reached the corner of the outer shape 20 of the molded product far from the resin injection port 9. The movable flow path is blocked. Therefore, the air trap 110 is generated when there is no place for air at the corner.

  Therefore, as shown in FIG. 11, a predetermined region 61 having a low space occupied fiber volume content and a predetermined region 62 having a high space occupied fiber volume content can be provided. In this shape, the flow front is changed to 104 by providing a low area and a high area in the occupied fiber volume content of the area, and a flow path to the air suction port 30 is secured, which appears in FIG. Such an air trap 110 can be eliminated.

  The FRP production method according to the present invention can be applied to the production of FRP using any RTM method, and is particularly suitable for mass production in which molding of excellent quality is required in a short cycle time. It is a thing.

DESCRIPTION OF SYMBOLS 1 RTM molding apparatus 2 Cavity 3 Mold 4 Upper mold 5 Lower mold 6 Press mechanism 7 Preform 8 Resin injection path 9 Resin injection port 10 Valve body 11 Heat medium flow path 12 Sealing material 20 Molded product outer shape 30 Resin suction port 40 Permitted Region 50 Reference surface 60 Predetermined region 61 Predetermined region 62 with low space occupied fiber volume content Predetermined region 70 with high space occupied fiber volume content 70 Cavity expansion portion 80 Region with reduced cavity height 90 Controlling the amount of reinforcing fiber substrate Area 100 Initial Flow Front 101 Flow Front 110 Air Trap 102 Improved Flow Front 103 Improved Flow Front 104 Improved Flow Front

Claims (5)

  A preform made of a reinforcing fiber base is placed in the cavity of the mold, and the resin injected from the resin injection port provided in the cavity flows in a direction toward the resin suction port provided in the cavity. In the method of manufacturing a fiber reinforced plastic, which is impregnated into a preform and curing the resin, the resin injection port and the resin suction port are provided in a region where the preform is disposed, and a predetermined inside of the cavity is provided. The volume occupied fiber volume content in the region is set within a range of ± 10% by volume with respect to the space occupied fiber volume content in the region including a predetermined reference plane in the cavity. Production method. The said space occupation fiber volume content rate is controlled by at least any one method of the following (a)-(c), The manufacturing method of the fiber reinforced plastics of Claim 1 characterized by the above-mentioned.
(A) The height of the cavity clearance is enlarged in a predetermined region.
(B) The cavity clearance is lowered in a predetermined region.
(C) The amount of reinforcing fibers used in the preform is controlled in a predetermined region. The height of the cavity clearance in the predetermined region is increased or decreased by 0.5 to 20% with respect to a predetermined reference region. Method. The amount of the reinforcing fiber used in the region having the volume occupied fiber volume content is changed within a range of ± 20% with respect to the amount of the reinforcing fiber in a predetermined reference region. 2. A method for producing a fiber-reinforced plastic according to 2. The method for producing a fiber-reinforced plastic according to any one of claims 1 to 4, wherein a space occupied fiber volume content in a region including a predetermined reference plane in the cavity is 30 to 70%.