Method for manufacturing composite material

A method for manufacturing a composite material includes placing a netlike sheet material, through which a resin composition permeates, on reinforcing fiber substrates disposed on a forming die. The method includes covering the reinforcing fiber substrates disposed on the forming die and the bag surface-smoothing sheet with a bag film to form a sealed forming space between the bag film and the forming die. The method includes infusing a resin composition into the forming space to impregnate the reinforcing fiber substrates. The method includes curing the resin composition impregnated in the reinforcing fiber substrates. Warp yarns and weft yarns are disposed in a lattice pattern and, after placing the bag surface-smoothing sheet on the reinforcing fiber substrates so that the warp yarns and the weft yarns form acute angles with respect to corners of the reinforcing fiber substrates, the bag surface-smoothing sheet projecting from the reinforcing fiber substrates is bent.

RELATED APPLICATIONS

The present application is a National Phase of International Application Number PCT/JP2017/014293 filed Apr. 5, 2017, and claims priority from Japanese Application Number 2016-077126 filed Apr. 7, 2016.

TECHNICAL FIELD

The present invention relates to a method for manufacturing a composite material and in particular to a method for manufacturing a large-sized composite material such as an aircraft part.

BACKGROUND ART

Fiber reinforced plastics (FRP) are lightweight and have excellent mechanical strength, and therefore the fiber reinforced plastics are used for structural members of aircraft, wind turbine blades, automobiles, ships, railroad vehicles, and the like.

As one method of forming fiber reinforced plastics, for example, a vacuum assisted resin transfer molding (VaRTM) method disclosed in PTL 1 is known.

In the VaRTM method, a plurality of reinforcing fiber substrates are laminated and disposed on a forming die, the reinforcing fiber substrates are covered with a pass medium that is a netlike sheet for resin diffusion in order to enhance resin impregnation efficiency, and the reinforcing fiber substrates and the pass medium are covered with a bag film that is a covering material. Then, a pressure in an interior of the bag film is reduced to a predetermined degree of vacuum, whereby a resin composition is injected into the bag film to be impregnated in the reinforcing fiber substrates, and then the impregnated resin is cured.

This VaRTM method is widely used as a method for manufacturing a large-sized composite material such as an aircraft part, because large-scaled equipment such as an autoclave which is used in an autoclave forming method is unnecessary.

The VaRTM method is being improved day by day, and, for example, in PTL 1, there has been proposed a method for manufacturing a composite material product using the VaRTM method, that is, a method for manufacturing a composite material in which it is possible to improve work efficiency and quality by using a silicone bag in which reinforcing fibers are disposed in an interior of a bag film enclosing a reinforcing fiber substrate.

CITATION LIST

Patent Literature

SUMMARY OF INVENTION

Technical Problem

Incidentally, composite materials for aircraft are required to have good, that is, smooth surface texture.

However, the reinforcing fiber substrate is made of a woven fabric formed of reinforcing fibers, and valleys and mountains are present in a portion where the fibers are present and a portion where the fibers are not present. Therefore, if in a resin impregnation step, the impregnated resin composition is cured as it is, the valley portions and the mountain portions remain as irregularities. The irregularities occur on a surface side facing the bag film. However, the irregularities can be eliminated by covering the surface side facing the bag film, of the reinforcing fiber substrate, with a sheet material such as a film or a net having appropriate rigidity, and filling a gap between the sheet material and the reinforcing fiber substrate with a resin composition.

On the other hand, in order to cover the reinforcing fiber substrate with the sheet material, it is necessary to bend the sheet material at corners forming peripheral edges of the laminated reinforcing fiber substrate. However, if a sheet material having high rigidity is used, it becomes difficult to bend the sheet material along the corners. In this manner, if a sheet material with poor shape conformability is forcibly bent by applying a load to a part of the sheet material, a position where a contact of the sheet material is strong and a position where a contact is weak locally occur in a bent area, and variation in content rate of reinforcing fibers subjected to FRP forming occurs in the corners of a formed product and a vicinity of the corners.

From the above, the present invention has an object to provide a method for manufacturing a composite material, in which even if a sheet material having high rigidity is used, bending of the sheet material at corners is easy.

Solution to Problem

According to the present invention, there is provided a method for manufacturing a composite material including: a placement step of placing a netlike sheet, through which a resin composition permeates, on a reinforcing fiber substrate disposed on a forming die; a covering step of covering the reinforcing fiber substrate and the netlike sheet disposed on the forming die with a bag film to form a sealed forming space between the bag film and the forming die; an injection/impregnation step of injecting the resin composition into the forming space to impregnate the reinforcing fiber substrate with the resin composition; and a resin curing step of curing the resin composition impregnated in the reinforcing fiber substrate, in which in the netlike sheet, a plurality of warp yarns and a plurality of weft yarns are disposed in a lattice pattern, and in the placement step, after the netlike sheet is placed on the reinforcing fiber substrate such that the warp yarns and the weft yarns form acute angles with respect to corners of the reinforcing fiber substrate, the netlike sheet protruding from the reinforcing fiber substrate is bent.

In the method for manufacturing a composite material according to the present invention, it is preferable that the acute angle between each of the warp yarns and the weft yarn of the netlike sheet and each of the corners of the reinforcing fiber substrate is in a range of 40 degrees to 50 degrees.

In the method for manufacturing a composite material according to the present invention, it is preferable that the netlike sheet has a quadrangle when viewed in a plan view, the warp yarns and the weft yarns form acute angles with respect to peripheral edges defining the quadrangle, and in the placement step, after the netlike sheet is placed on the reinforcing fiber substrate such that the peripheral edges of the netlike sheet and the corners of the reinforcing fiber substrate are parallel to each other, the netlike sheet protruding from the reinforcing fiber substrate is bent.

In the method for manufacturing a composite material according to the present invention, it is preferable that the netlike sheet has a quadrangle when viewed in a plan view, the warp yarns and the weft yarns are orthogonal to peripheral edges defining the quadrangle, and in the placement step, after the netlike sheet is placed on the reinforcing fiber substrate such that the peripheral edges of the netlike sheet form acute angles with respect to the corners of the reinforcing fiber substrate, the netlike sheet protruding from the reinforcing fiber substrate is bent.

In the method for manufacturing a composite material according to the present invention, it is preferable that the method for manufacturing a composite material further includes a vacuum suction step of evacuating the forming space after the covering step and the injection/impregnation step is performed in the evacuated forming space.

Advantageous Effects of Invention

According to the method for manufacturing a composite material according to the present invention, even if a netlike sheet having high rigidity is used, bending of the netlike sheet at corners is easy.

DESCRIPTION OF EMBODIMENTS

This embodiment relates to a method for manufacturing a composite material100having a laminated body110composed of a plurality of reinforcing fiber substrates2, and a matrix resin120obtained by curing a resin composition C impregnated in the laminated body110, as shown inFIG. 1C.

Further, this embodiment relates to an example in which a VaRTM method is applied to the present invention. Further, in this specification and claims, the expression “resin composition” is used to specify a state where it has not yet been cured, and is distinguished from “resin” in a case where it is already cured.

Hereinafter, a method for manufacturing the composite material100will be described.

First, as shown inFIG. 2, a predetermined number of rectangular sheet-like reinforcing fiber substrates2are stacked on a forming die1. The laminated body110having the laminated reinforcing fiber substrates2has a rectangular parallelepiped appearance. The upper surface and the four side surfaces of the laminated body110are connected to each other through corners111, respectively. Then, as shown inFIG. 1A, a peel ply3(a release sheet) is placed on the laminated body110, and a bag surface-smoothing sheet4is placed on the peel ply3. Further, pass medium5is disposed on the bag surface-smoothing sheet4.

Both the bag surface-smoothing sheet4and the pass medium5are netlike sheet materials through which the resin composition C penetrates. However, the main purpose of the bag surface-smoothing sheet4is to smooth the surface facing a bag film6, of the composite material100, whereas the main purpose of the pass medium5is to uniformly and quickly infiltrate the resin composition C into the laminated body110.

The forming die1is made of an iron-based metal material, for example, structural steel such as JIS SS400, stainless steel such as JIS SUS304, or an Invar alloy having a typical composition of 36 mass % Ni—Fe. However, the material configuring the forming die1is arbitrary as long as it exerts the function thereof, and gypsum, fiber reinforced plastic, or the like can be used. In this embodiment, the forming die1has a rectangular parallelepiped shape with a flat surface on which the reinforcing fiber substrate2is placed. However, the shape thereof is specified according to the shape of the composite material100to be manufactured.

The reinforcing fiber substrate2is composed of any known fibers such as carbon fibers, aramid fibers, or glass fibers, for example.

The peel ply3is provided in order to peel the bag surface-smoothing sheet4and the pass medium5and the bag film6above the bag surface-smoothing sheet4from the formed composite material100shown inFIG. 1C.

The peel ply3is configured with a woven fabric composed of chemical fibers, through which the resin composition C which is injected into a forming space S (described later) can penetrate, and which has releasability.

The bag surface-smoothing sheet4has moderate rigidity on the premise that the resin composition C injected from an injection port8permeates therethrough, and has smoothness for smoothing the surface facing the bag film6, of the composite material100.

The bag surface-smoothing sheet4is made of a netlike sheet in which a plurality of meshes46penetrating the front and back surfaces are formed, as shown inFIG. 3A. The injected resin composition C is impregnated in the reinforcing fiber substrate2through the meshes46of the bag surface-smoothing sheet4(refer toFIG. 1B).

In the bag surface-smoothing sheet4, in order to have smoothness, the opening size (mesh) of the mesh46is set to be smaller than in the pass medium5.

The bag surface-smoothing sheet4has a quadrangle when viewed in a plan view, as shown inFIG. 3A. However, in this embodiment, in consideration of placing the bag surface-smoothing sheet4on the laminated body110having a rectangular parallelepiped shape, as shown inFIG. 2, the bag surface-smoothing sheet4has a main body41which is placed on the upper surface of the laminated body110, and four bent portions42respectively protruding from four peripheral edges45defining the main body41. InFIG. 2, in order to facilitate understanding, illustration of the peel ply3is omitted.

After the bag surface-smoothing sheet4is placed on the laminated body110, the respective bent portions42corresponding to the corners111of the laminated body110are bent downward from boundary portions (the peripheral edges45) between the bent portions42and the main body41, whereby the bent portions42are brought into contact with the side surfaces of the laminated body110.

Further, warp yarns43and weft yarns44are provided in a lattice pattern on the surface of the bag surface-smoothing sheet4, as shown inFIG. 3A. The warp yarns43and the weft yarns44are means for imparting rigidity to the bag surface-smoothing sheet4. The warp yarns43and the weft yarns44are strength imparting materials added to the bag surface-smoothing sheet4.

The warp yarns43are aligned parallel to each other and the weft yarns44are aligned parallel to each other, as shown inFIG. 3A. The warp yarns43and the weft yarns44intersect each other, and here, an example is shown in which the warp yarns43and the weft yarns44are disposed orthogonally to each other and in a lattice pattern.

Then, if each of the warp yarns43is disposed such that an angle θ1between the warp yarn43and the peripheral edge45of the bag surface-smoothing sheet4forms an acute angle, each of the weft yarns44is also disposed such that an angle θ2between the weft yarn44and the peripheral edge45forms an acute angle, similar to the warp yarn43. In this embodiment, an example is shown in which the angle θ1and the angle θ2coincide with each other at 45 degrees.

In this manner, in a case where one of the angle θ1and the angle θ2is an acute angle, the other is also an acute angle. In this specification and claims, the acute angle means that both the angle θ1and the angle θ2are acute angles. The same applies to a case where in this specification, either one of the angle θ1and the angle θ2is pointed to be an acute angle.

The angle θ1and the angle θ2are preferably in a range of 40 degrees to 50 degrees. As shown inFIG. 5, in a case where the angle θ1is in a range of 40 degrees to 50 degrees (the angle θ2is in a range of 50 degrees to 40 degrees), the bag surface-smoothing sheet4has desired stretchability in both the X direction and the Y direction shown inFIG. 6. Thereby, as shown inFIG. 6, when the bent portion42is bent downward, a portion thereof being in contact with the corner111is appropriately stretched to prevent the bent portion42from coming into contact with the laminated body110with uneven strength, and thus the bent portion42can be bent uniformly.

In particular, in a case where each of the angle θ1and the angle θ2is 45 degrees, the bag surface-smoothing sheet4is stretched substantially evenly in the X direction and the Y direction, and therefore, it is possible to more easily bend the bent portion42without considering a difference in stretchability in the X direction and the Y direction.

Further, the warp yarn43and the weft yarn44have the configurations described above, whereby the bag surface-smoothing sheet4is disposed such that the peripheral edge45substantially coincides with the corner111, as shown inFIG. 6. Then, when the bent portion42is brought into contact with the side surface of the laminated body110, high shape conformability is obtained.

Specifically, if the peripheral edge45is disposed so as to substantially coincide with the corner111, the warp yarn43is disposed such that the angle θ3between the warp yarn43and the corner111is an acute angle. For this reason, the angle between each of the warp yarn43and the weft yarn44and the peripheral edge45of the main body41, the length of each of the warp yarn43and the weft yarn44extending from a place where the main body41and the upper surface of the laminated body110are in contact with each other, or the like is different from that in a case where the warp yarn43is disposed so as to be orthogonal to the peripheral edge45of the main body41(a dot-and-dash line inFIG. 6). For this reason, the bag surface-smoothing sheet4is easily stretched in the X direction and the Y direction, and the warp yarn43and the weft yarn44easily bend. Therefore, high shape conformability is obtained.

Due to the stretchability and the shape conformability described above, if the bag surface-smoothing sheet4is placed on the laminated body110with the peripheral edge45made to coincide with the corner111and the bent portion42is bent downward so as to come into contact with the side surface of the laminated body110, the portion of the bag surface-smoothing sheet4corresponding to the corner111does not strongly hit against the corner111. The contact strength of an area corresponding to the corner111when the bent portion42is bent according to this embodiment in this manner was measured. As a result, as shown inFIG. 7A, the bent portions corresponding to the corners111along the peripheral edges45hit against the corners111with substantially the same strength.

If a bag surface-smoothing sheet70in which the warp yarns43and the weft yarns44are orthogonal to peripheral edges75, as shown inFIG. 3B, is placed on the composite material100such that the peripheral edge75is parallel to the corner111and is bent, a position where a contact is strong and a position where a contact is weak appear, as shown inFIG. 7B.

The materials of the warp yarn43and the weft yarn44are not limited as long as they can impart desired rigidity to the bag surface-smoothing sheet4. However, the warp yarn43and the weft yarn44can be made of any known fiber resin such as polyester resin, for example. The warp yarn43and the weft yarn44are alternately positioned one above and the other below, as shown inFIG. 4. That is, the warp yarns43,43. . . and the weft yarns44,44. . . as the rigidity imparting materials are formed by being woven with a plain weave. Then, a distance A between the warp yarns43adjacent to each other is about twice a thickness D. The same applies to the weft yarns44.

The pass medium5which is placed on the bag surface-smoothing sheet4is made of a netlike sheet, similar to the bag surface-smoothing sheet4. However, the pass medium5is provided to promote uniform infiltration of the resin composition C injected from the injection port8into the laminated body110(refer toFIG. 1B).

The pass medium5has the same planar shape as the bag surface-smoothing sheet4, although illustration is omitted. However, the pass medium5does not have a rigidity imparting material. For this reason, the pass medium5has lower rigidity than the bag surface-smoothing sheet4. The pass medium5aims to promote uniform infiltration of the resin composition C, and therefore, the pass medium5may have rigidity lower than that of the bag surface-smoothing sheet4.

Similar to the bag surface-smoothing sheet4, a plurality of meshes penetrating the front and back surfaces are formed in the pass medium5. However, the opening size (mesh) of the mesh is larger and the porosity is higher than in the bag surface-smoothing sheet4.

Here, in general, in the pass medium which is used in the VaRTM method, it can be said that the higher the porosity is, the higher the diffusivity of resin is. The resin composition C flowing through the mesh of the pass medium diffuses with the space between the pass medium5and the laminated body110as a flow path and is impregnated in the laminated body110.

Thereafter, as shown inFIG. 1A, the reinforcing fiber substrate2, the peel ply3, the bag surface-smoothing sheet4, and the pass medium5installed on the forming die1, as described above, are covered with the bag film6. A seal member11is provided between the peripheral edge of the bag film6and the upper surface of the forming die1, whereby a sealed forming space S is formed between the bag film6and the forming die1. The reinforcing fiber substrate2, the peel ply3, the bag surface-smoothing sheet4, and the pass medium5are disposed in the forming space S. The bag film6is provided with a suction port7and the injection port8, and as shown inFIG. 1B, the suction port7is connected to a vacuum pump9and the injection port8is connected to a storage tank10in which a liquid resin composition C is stored.

After the forming space S is formed between the bag film6and the forming die1, as shown inFIG. 1B, the vacuum pump9is driven to perform suction through the suction port7to reduce the pressure in the forming space S (evacuation). A forming load composed of a differential pressure between the pressure in the forming space S and the atmospheric pressure outside the bag film6acts on the reinforcing fiber substrate2disposed in the forming space S through the bag surface-smoothing sheet4and the pass medium5.

Therefore, the bag surface-smoothing sheet4is pressed against the laminated body110through the peel ply3. The bag surface-smoothing sheet4has high rigidity due to the rigidity imparting material. Therefore, in a resin impregnation step which will be described later, formation of irregularities on the surface of the composite material100, which is caused by a free flow of the resin composition C, can be prevented.

Then, if the reduction of the pressure in the forming space S is further continued, since the storage tank10is connected to the injection port8, as shown inFIG. 1B, the liquid resin composition C in the storage tank10is injected into the forming space S under reduced pressure through the injection port8. The resin composition C injected into the forming space S sequentially passes through the pass medium5, the bag surface-smoothing sheet4, and the peel ply3and is impregnated in the reinforcing fiber substrate2.

The resin composition C may be, for example, thermosetting resin that is cured by heating, such as unsaturated polyester resin, epoxy resin, polyamide resin, or phenol resin, or may be thermoplastic resin that is typified by nylon, polyethylene, polystyrene, polyvinyl chloride, polybutylene terephthalate, or the like.

In this embodiment, the pass medium5having porosity higher than that of the bag surface-smoothing sheet4is disposed on the bag surface-smoothing sheet4. For this reason, the impregnation amount of the resin composition C becomes substantially equal over the entire area of the surface of the pass medium5. Thereby, even if the mesh46of the bag surface-smoothing sheet4has a smaller opening size than the mesh of the pass medium5and the diffusion efficiency in the bag surface-smoothing sheet4is lower than that in the pass medium5, even diffusion of the resin composition C into the laminated body110can be secured.

In this manner, on the premise that it is possible to supply the resin composition C to the laminated body110even with only the bag surface-smoothing sheet4, It is possible to prevent the formation of irregularities on the surface of the composite material100due to the use of the coarse mesh of the pass medium5for improvement in the diffusion rate of the resin composition C.

After the reinforcing fiber substrate2is impregnated with a necessary amount of the resin composition C, the impregnated resin composition C is cured. Specifically, in a case where the resin composition C is thermosetting resin, it is cured by heating the forming space S. In order to heat the resin composition C, any heating device can be used. On the other hand, in a case where the resin composition C is thermoplastic resin, the molten resin is cooled and cured. Also in the curing step of the resin composition C, it is preferable to maintain the forming space S under reduced pressure.

After the resin composition C is cured, pressure reduction and heating (or cooling) are released. Then, after the connection between the suction port7and the vacuum pump9and the connection between the injection port8and the storage tank10are released, the peel ply3is peeled off from the cured composite material100to remove the bag surface-smoothing sheet4, the pass medium5, and the bag film6. Thereafter, the formed composite material100is removed from the forming die1.

With the above, a series of steps of forming the composite material100is finished.

Next, the composite material100which is manufactured by the method for manufacturing the composite material100according to this embodiment described above will be described.

The composite material100has the matrix resin120and the laminated body110, as shown inFIG. 1C. In the laminated body110, it is preferable that reinforcing fibers are included in a predetermined range in the matrix resin120, as described below.

That is, if the amount of the reinforcing fibers which are included in the composite material100is small, the strength of the composite material100cannot be sufficiently secured, and conversely, if the amount of the reinforcing fibers which are included in the composite material100is large, the number of intersections of the warp yarns43and the weft yarns44increases, and thus there is a concern that voids may be generated during the [resin impregnation step]. The amount of the reinforcing fibers which are included in the composite material100can be appropriately set according to the use or the like of the composite material100.

If the bag surface-smoothing sheet4of this embodiment is used, even in a corner R of the corner111which is described below, the amount of the reinforcing fibers in the corner111and the vicinity thereof can be determined to be in a desired range.

The shape of the composite material100is substantially a rectangular parallelepiped shape, similar to the laminated body110before it is impregnated with the resin composition C. The dimension of the corner130of the composite material100should be set according to the specification of the composite material100. However, in the cross-sectional shape shown inFIG. 1C, the corner R can be set to 10.0 mm or less and can be set to 5.0 mm or less. Even in the corner130having the dimension in this range, the amount of the reinforcing fibers can be determined to be within a desired range.

Hereinafter, the effects that the method for manufacturing the composite material of this embodiment and the composite material exhibit will be described.

According to the present invention, when the bag surface-smoothing sheet4is disposed, the warp yarn43(the weft yarn44) is disposed such that the angle θ3with respect to the corner111of the laminated body110forms an acute angle, whereby, when the bent portion42is bent, the warp yarn43(the weft yarn44) is subjected to shear deformation in the “placement step” described above. Therefore, the warp yarn43(the weft yarn44) is easily conformed to the corner R. For this reason, as shown inFIG. 7, it is possible to make the content rate (VF) of the reinforcing fibers after FRP forming in the vicinity of the corner130of the composite material100uniform, compared to the related art. Further, in the “vacuum suction step” described above, since the bag surface-smoothing sheet4has necessary rigidity, it is possible to prevent formation of irregularities on the surface of the composite material100, which is generated by a free flow of the resin composition C. As a result, the surface of the composite material100can have a predetermined surface roughness.

Further, as shown inFIG. 3A, the warp yarns43are disposed such that the angle θ1between each of the warp yarns43and the peripheral edge45of the bag surface-smoothing sheet4is an acute angle, whereby it is possible to dispose the warp yarn43such that the angle θ3between the warp yarn43and the corner111becomes an acute angle, when the bag surface-smoothing sheet4is placed on the laminated body110, similar to the related art.

Further, in the manufacturing method of the related art, the bag surface-smoothing sheet4is merely added as a member which is used, and therefore, the present invention can be easily implemented.

Furthermore, due to using the bag surface-smoothing sheet4, it is possible to improve work efficiency, because there is no need for a step of cutting the bag surface-smoothing sheet4before use, as in a case where the bag surface-smoothing sheet70in which the warp yarns43are orthogonal to the peripheral edge45, as shown inFIG. 3B, is disposed in a state where it has been rotated in the circumferential direction such that the angle θ3which is an acute angle is formed.

Further, even if the formed composite material100has the corner130, it is possible to make the VF in the vicinity of the corner130a desired value, and even if the corner130has R of 5.0 mm or less in the cross-sectional shape, the VF in the vicinity of the corner130can be made to be a desired value. Further, these composite materials100can be obtained with good yield.

The preferred embodiment of the present invention has been described above. However, it is possible to select the configurations described in the embodiment or appropriately change the configurations to other configurations without departing from the gist of the present invention.

The method for manufacturing the composite material100according to this embodiment has been described by taking the VaRTM method as an example. However, there is no limitation thereto, and the present invention is applied to a general resin forming method in which resin is injected into a forming space while reducing the pressure in the forming space in which a reinforcing fiber substrate is disposed. For example, the present invention can also be applied to, for example, forming methods other than the VaRTM method, such as a resin impregnation forming method (RTM: Resin Transfer Molding) or a reduced pressure type resin impregnation forming method (Light-RTM).

Further, in the present invention, as shown inFIG. 3B, the bag surface-smoothing sheet70may be used. In this case, the position at which the bag surface-smoothing sheet70is placed on the laminated body110is adjusted such that the warp yarns43and the weft yarns44of the bag surface-smoothing sheet70form acute angles θ3with the corners111of the laminated body110.

Further, in this embodiment, the warp yarns43and weft yarns44as the rigidity imparting materials are provided on the bag surface-smoothing sheet4. However, the present invention is not limited thereto. Warp yarns and weft yarns themselves configuring the bag surface-smoothing sheet4can be made of highly rigid materials such as polyester or nylon, and the rigidity can also be imparted by setting the diameters of the yarns.

The same applies to the pass medium5, and it is possible to provide rigidity imparting materials such as the warp yarn43and the weft yarn44to the pass medium5. Warp yarns and weft yarns themselves configuring the pass medium5can be made of highly rigid materials such as polyester or nylon, and the rigidity can also be imparted by setting the diameters of the yarns. Thereby, in the [vacuum suction step], it is possible to more reliably prevent formation of irregularities on the surface of the composite material100, which is caused by a free flow of the resin composition C.

Further, in the manufacturing method of this embodiment, two netlike sheets, namely, the bag surface-smoothing sheet4and the pass medium5, are used. However, the present invention permits the use of only one netlike sheet. Thereby, the number of members which are used in the manufacturing method can be reduced.

In the bag surface-smoothing sheet4and the pass medium5, meshes are provided to form voids into which the resin composition C flows. However, the materials of the bag surface-smoothing sheet4and the pass medium5can be changed according to the composite material100to be manufactured. Thereby, the surface texture of the composite material100can be improved, or the work efficiency can be improved.

The shape of the composite material100can be appropriately selected from not only a rectangular parallelepiped shape but also various shapes according to the use thereof. In that case, it is necessary to prepare the laminated body110which is substantially equal to the selected shape.

REFERENCE SIGNS LIST