JPH04282231A - Preparation of composite molded product - Google Patents

Abstract

PURPOSE:To efficiently prepare an integrated composite molded product wherein a surface layer part is composed of a resin phase containing a fibrous reinforcing material and a core part is composed of a porous resin phase containing air bubble particles. CONSTITUTION:An extensible air permeable sheet (11) permitting the passage of gas and the penetration of a resin but preventing the free passage of the resin, a sheet (12) composed of a fibrous reinforcing material and a mixture (14) of foamable particles and a thermosetting resin are received in a mold and the mold is closed to perform molding under heating. The gas generated at the time of molding is discharged from the molding space of the mold through the air permeable sheet.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing composite molded articles. More specifically, (a) a surface layer made of a thermosetting resin phase containing a fibrous reinforcing material; and (b)
The present invention relates to a method for efficiently producing an integrated composite molded article substantially composed of a core made of the porous resin phase containing cellular particles (foam-containing particles).

0002

[Prior Art] Composite molded products having a foam core and a surface layer made of fiber-reinforced resin have been put to practical use in various fields because of their lightness and toughness. Improved molded articles and manufacturing methods are proposed. As a method for manufacturing a composite molded product having the above-described structure, for example, the foam core of the core is molded in advance, this molded product is wrapped with a woven fabric as a reinforcing material, and then inserted into a mold. A method is to inject liquid molding resin into the mold to form the surface layer, and then remove the composite molded product from the mold.Alternatively, the material that will become the surface layer is pre-molded and foamed urethane resin, etc. is injected into the void in the center. However, a method of obtaining a composite molded article by forming a foamed core within the void is known. However, these conventionally known techniques have the following disadvantages: (1) The steps for obtaining a composite molded product are diverse and the operations are complicated, resulting in low production efficiency and high costs for the molded product, and (2) The strength and appearance of the resulting composite molded product are unsatisfactory, and (3) the shape and size of the composite molded product are limited.

[0003] In order to improve these problems, the present inventors have already provided in European Patent Application Publication No. 407,996 a fibrous reinforcing material and a separation layer constituting the surface layer of the molded product on the cavity surface of the mold, and a separation layer surrounded by these. Expandable particles and thermosetting resin are placed in a space and heated, the particles expand in volume, and the expansion force presses the fibrous reinforcing member against the internal constraint surface of the mold to shape it, and then heat it. We proposed a method of curing a curable resin to form a composite molded article having a surface layer made of fiber-reinforced resin and a porous core.

Although this method has greatly improved the drawbacks of conventionally known techniques, it still prevents the thermosetting resin impregnated into the fibrous reinforcing member from entering the mold holes or overflowing from the parting area. This resulted in burrs, and it was necessary to remove the burrs from the resulting composite molded product and finish it. These burrs are often formed in places that pose a problem in terms of appearance, and the finishing work requires a lot of man-hours. Furthermore, burrs often remain on the mold and must be removed, making it necessary to clean the mold.

[0005]

[Problems to be Solved by the Invention] An object of the present invention is to provide a composite material substantially formed of a surface layer made of fiber reinforced resin (FRP) and a core portion containing foamed particles (cell-containing particles). The objective is to obtain molded products through relatively simple operations. Furthermore, the resulting composite molded product has almost no burrs, or has burrs in predetermined locations and in a predetermined shape, so that the finishing work does not require many man-hours. Furthermore, it is intended to facilitate cleaning of the mold without leaving any burrs on the mold.

[0006]

[Means for Solving the Problems] According to the research conducted by the present inventors, the object of the present invention is to provide a surface layer portion made of a thermosetting resin phase containing a fibrous reinforcing material and a resin containing foamed particles. A method for manufacturing an integrated composite molded article comprising a core having a phase, the method comprising: (a) allowing gas flow to the inner wall side of a substantially sealed molding die; (b) installing the fibrous reinforcement through a stretchable breathable sheet with pores that allow penetration of the resin but prevent its free flow; (b) the inner wall of the fibrous reinforcement; (c) expanding the expandable particles by increasing the temperature to cause volume expansion of the aggregate of the particles;
(d) The thermosetting resin or its precursor is infiltrated into the fibrous reinforcing material while pressing the breathable sheet and the fibrous reinforcing material against the inner wall surface of the mold by the volumetric expansion in (c) above; (e) discharging the gaseous components in the space of the mold from the breathable sheet to the outside of the space, thus allowing the thermosetting resin or its precursor to exist between the breathable sheet, the fibrous reinforcement and the expandable particles; (e) then; It is characterized by a step of curing the thermosetting resin or its precursor to complete solidification to form the surface layer portion and the core portion, and (f) removing the composite molded product thus obtained from the mold. It has been found that this can be achieved by a method for manufacturing a composite molded article.

[0007] In the method of the present invention as described above, foaming of expandable particles is carried out in a mold by raising the temperature, thereby causing volumetric expansion of an aggregate of these particles, and maximizing the force of this volumetric expansion. By making effective use of the limit, the fluid thermosetting resin or its precursor present in the mold can sufficiently penetrate into the fibrous reinforcing material, and the resin present in the mold space during molding can be effectively utilized. The air generated during molding and the gas generated during molding are effectively discharged out of the mold through the pores of the breathable sheet.

[0008] If there is no breathable sheet, the thermosetting resin or its precursor will leak from the surface of the fibrous reinforcing material and enter the parting line of the mold, the slide core, the gap between the dowel pins, etc. and form burrs. However, this can be prevented by the presence of a breathable sheet. In addition, if an airtight film such as polyvinyl chloride, ABS, polyvinylidene chloride, or polycarbonate is used instead of a breathable sheet, the air existing in the mold space and the gas generated during molding will have a place to escape. Product defects such as losses, voids, and air traps occur.

[0009] Therefore, in the present invention, the use of a breathable sheet is essential for achieving the purpose. This breathable sheet must be capable of allowing impregnation with the thermosetting resin or its precursor but preventing its free flow.

[0010] A further desired performance of the breathable sheet is that it can withstand the pressure caused by the volumetric expansion of the particle aggregate. As a result of the volumetric expansion, if the air-permeable sheet is torn or holes are formed and the thermosetting resin or its precursor passes through the air-permeable sheet, it becomes difficult to achieve the purpose. For this purpose as well, it is necessary to have appropriate elasticity.

Specific examples of breathable sheets include stretchable nonwoven fabrics (for example, nylon nonwoven fabrics, polyester nonwoven fabrics), slab foams (for example, ether polyurethane foams), but any of these may be used as long as they satisfy the purpose of the present invention. It is not limited to.

[0012] Since this breathable sheet has the role of preventing foam particles, thermosetting resin, or its precursor from leaking out and forming burrs, it is convenient to process it into a bag-like structure in advance. There are cases.

[0013] Depending on the shape of the molded product, the presence of this breathable sheet may create a large resistance to the pressure generated by the volume expansion of the expandable particles, and the thermosetting resin or When the precursor hardens, it may not penetrate sufficiently into the fibrous reinforcing material, resulting in insufficient wetting of the surface of the molded product or product defects such as voids.

[0014] In this case, a part constituting an air trap is provided between the breathable sheet and the fibrous reinforcing material or in a part that will become the core by selecting a part of the molded product that will not cause problems in terms of its performance or appearance. The above problem can be solved by storing gas components in the space, excess thermosetting resin or its precursor, etc. inside the member.

[0015] For composite molded products made by such a method, there are cases in which this part can be left as is even after the molding is completed, and
If necessary, finishing may be done by cutting around the part of the member constituting the air trap, but even in the latter case, the finishing work is easy because burrs always occur at certain locations.

[0016] The members constituting the air trap maintain their shape without being crushed by the pressure generated by the volume expansion of the expandable particles during molding, and also prevent gas components in the space and excess thermosetting resin from being crushed. Or, when the precursor thereof enters, a structure is required that provides resistance equal to or higher than the resistance caused by the presence of the breathable sheet against the pressure caused by the volumetric expansion of the expandable particles. In addition, when the member is installed between the breathable sheet and the fibrous reinforcing material, and the gas component in the internal space escapes from the member,
Product defects such as voids can be prevented by allowing the material to pass through directly to the breathable sheet side. When installing the member at the core portion, it is necessary to have a structure that prevents gas components from escaping within the internal space, or to ensure that if they do escape, they can escape directly from the breathable sheet. In practice, members constituting the air trap that satisfy this condition are often selected through trial and error when molding each composite molded product.

The expandable particles used in the method of the present invention are resin particles whose volume expands when heated, such as polystyrene, polyvinylidene chloride, polyolefin, polyphenylene oxide, which are known as expandable thermoplastic resin particles, and their like. Expandable particles such as copolymers and porous elastic particles are compressed under pressure and the surface is softened by heat.
A material coated with a resin soluble in a molten or liquid thermosetting resin may be used, but the material is not limited thereto.

Together with these expandable particles, they can improve mechanical properties, absorb the reaction heat generated when the thermosetting resin or its precursor hardens, and control rapid temperature rises to prevent localized high temperature areas. In order to prevent this from occurring, inorganic hollow particles such as non-expandable glass balloons and shirasu balloons, organic foamed particles such as already foamed polyethylene/polypropylene and polyvinylidene chloride, milled glass, silicon carbide whiskers, mica, Additives such as iron powder, calcium carbonate, short fibers such as silica sand, powder and granules can be added.

In particular, the combined use of inorganic or organic non-expandable hollow/expanded particles is often preferable from the viewpoint of light weight, which is a characteristic of the composite molded article that is the object of the present invention.

From a similar point of view, polyurethanes, polyamides, polypropylenes, which have already been foamed together with expandable particles,
It is also possible to have one or more lightweight objects of a certain size and a specific gravity of 0.5 or less, such as rigid foams such as polystyrene, lightweight materials such as balsa wood, synthetic resins, hollow bodies made of aluminum, etc. . These do not necessarily have to have the same shape as the intended composite molded product.

Further, as the thermosetting resin used in the method of the present invention, epoxy resin, polyurethane resin, unsaturated polyester resin, vinyl ester resin, polyimide resin, phenol resin, polyamide resin, polycycloolefin resin, etc. are used. but is not limited to these.

[0022] Thermosetting resins are commonly used in the following manners:
A curing agent and/or accelerator are used in combination in the resin or its precursor (for example, raw material monomer), and these can be used in combination in the method of the present invention as well.

[0023] Thermosetting resins or their precursors that are solid at room temperature and exhibit fluidity when heated can also be used, and in some cases this may be preferable.

The fibrous reinforcing material forming the surface layer is as follows:
Specifically, preferred materials include glass fibers, carbon fibers, silicon carbide fibers, metal fibers, aramid fibers, polyarylate fibers, polyolefin fibers, and mixed fibers of two or more of these fibers. In addition to these fibers, polyester fibers, polyamide fibers, viscose fibers, natural fibers or asbestos can also be used. These fibers may be short fibers, long fibers, or whiskers, but long fibers, particularly continuous fibers, are preferred. These are used in the form of sheets such as woven fabrics, knitted fabrics, nonwoven fabrics, rovings, webs, mats, and papers, and each can be used in two or more layers.

[0025] On the side of the fibrous reinforcing material that is in contact with the mixture of the expandable particles and the thermosetting resin or its precursor, a thermosetting resin or a thermosetting resin that does not substantially pass through the expandable particles but has fluidity during molding is applied. The precursor can be applied with a separating layer through which it passes. The separation layer can also be a structural material integrated with the fibrous reinforcement forming the surface layer. The separation layer allows only the thermosetting resin or its precursor to penetrate into the fibrous reinforcing material, reach the surface layer, and harden, making it possible to obtain a dense surface layer that does not contain expandable particles. It is also possible to address cases where special characteristics are required. As this separation layer, a woven fabric with a small opening,
Examples include knitted fabrics, nonwoven fabrics, webs, paper, wire mesh, and porous membranes, and specific examples include those described by the present inventors in European Patent Application Publication No. 407996, Japanese Patent Application No. 181486/1996, and the like.

Furthermore, a thermosetting resin or its precursor is present between the fibrous reinforcing material and the separation layer, and the expandable particles are present on the opposite side of the separation layer from the fibrous reinforcing material, and molding is performed. You can also do that.

In the method of the present invention, the above-mentioned breathable sheet is placed in contact with the inner wall of a mold, a fibrous reinforcing material is placed inside the sheet, and a fibrous reinforcing material is placed inside the sheet at a position that will become the core of the molded product. , molding is performed by positioning the expandable particles and the above-mentioned resin, but the resin may be placed in the mold together with other materials in advance,
Other materials may also be injected into the mold after it has been placed in the mold as described above.

[0028]

[Effects of the Invention] By the method of the present invention, a composite molded product in which the surface layer is a fiber-reinforced resin layer and the core is a foamed molded product such as syntactic foam, and the resin phases of both are integrated, can be processed for burrs, etc. As an easy molded product, it can be obtained by a relatively simple operation that does not require operations such as adhesion, so-called one-stage molding.

[0029]

[Examples] The present invention will be explained in more detail with reference to Examples below. However, these are for illustrating the present invention, and do not restrict or limit the scope of the present invention. Furthermore, in the examples, parts are simply parts by weight.

[0030]

[Embodiment 1] This example is an example in which a model of an automobile trunk lid is prototyped.

First, a mold shown in FIG. 1 was prepared. In FIG. 1, 1 is an upper die of a mold, and 2 is a lower die, which form a pair. In this mold, the following 11, 12, 13 and 1 are placed as shown in the figure.
I put 4. That is, 11 is a stretchable breathable sheet according to the present invention, which has pores that allow gas flow and penetration of thermosetting resin but prevents its free flow; This is a reinforcing fiber sheet that is the main reinforcing fiber of the material FRP, and 13 is a separation layer that substantially does not allow foamable particles to pass through, but allows a flowable thermosetting resin or its precursor to pass through during molding. 14 is a mixture of expandable particles and a thermosetting resin or its precursor.

As Nos. 11 and 13, stretchable nonwoven fabrics made of opened long fibers were used. It is made of long fibers of polyester and polypropylene. These are expandable particles (“Matsumoto Microspheres” F), which will be described later.
-30D, "Expancel" DU461) does not pass,
Epoxy resin is transparent. No. 11 is more densely woven than No. 13, has a basis weight of 120 g/m2, and is re-calendered, and the opening is such that the resin can penetrate through it but cannot pass through it freely. No. 13 has a slightly coarse mesh and a basis weight of 40 g/m2, allowing the resin to pass through it freely.

The 12 reinforcing fiber sheets were manufactured by Nittobo (
Glass fiber cloth WF-181-100BV (
(satin weave), and two sheets of each were used.

As a thermosetting resin, "Epicote 807" manufactured by Yuka Shell Co., Ltd. and a curing agent "Epomate YLH-0" were used.
06" in a ratio of 100 parts to 31 parts, and to this 100 parts, "Matsumoto Microsphere F-30D" manufactured by Matsumoto Yushi Seiyaku Co., Ltd. was mixed in a ratio of 10 parts. It was used as mixture 14.

As shown in FIG. 1, a mixture 14 was placed between a stack of a breathable sheet 11, a reinforcing fiber sheet 12, and a separation layer 13, and placed in a mold. 11 and 12 above in the mold
, 13 are arranged so that 11 is on the outside and 13 is on the inside,
The ends of 11 were cut to a size that would fit into the air/resin reservoir 3 of the mold, 13 was cut to a size that would fit between the molds, and 12 was cut to a size that would fill the mold.

The upper mold 1 and the lower mold 2 of the mold were closed together and successively heated to 85°C. The epoxy resin begins to harden, at the same time the expandable particles expand, and the resin becomes a separating layer of the nonwoven fabric 13.
It reached the reinforcing fiber sheet 12 through it, and further reached the nonwoven fabric 11 which becomes a breathable sheet, and a part of it passed through this nonwoven fabric 11 and reached the air/resin reservoir 3. The air inside the mold is filled with both nonwoven fabrics,
The resin, including that in the reinforcing fiber sheet, was discharged into the air/resin reservoir 3 through the resin path and ahead of the resin. The final remaining portion was discharged together with the resin in step 3.

At this time, depending on the shape of the molded product, although it was not necessary in this embodiment, it may be preferable to quickly discharge some of the air and resin from the air vents 4 and 5 through the nonwoven fabric 11. Further, it may be preferable to exhaust the air from the exhaust hole 6 or the like using a vacuum pump, if necessary.

After one hour, the molded product was cooled and taken out from the mold. A good trunk lid model was obtained by cutting off only the resin-impregnated nonwoven fabrics 11 and 13 that protruded from the ends of the molded product.

Molding was carried out in the same manner, with only the assembly of the nonwoven fabric, reinforcing fiber sheet, and resin mixture changed. In other words, the nonwoven fabric 13 serving as a separation membrane is shaped like a bag, and the resin mixture 1 is added to it.
Place 4 and close (stitch together and heat seal)
Only the nonwoven fabric 11 that would become the breathable sheet was sandwiched between the molds so that the nonwoven fabric 13 that would become the separation layer would fit completely into the mold.

The molded product obtained was the same as above, and by cutting out only the resin-impregnated material of the nonwoven fabric 11, a good trunk lid model was obtained in which the outer layer was made of FRP and the inner layer was made of syntactic foam core.

[0041]

[Embodiment 2] This example is an example of making a round bar as a prototype.

In this example, there are two molds on the left and right as shown in FIG.
Divided molds 21 and 22 were used. This mold has air/
It has a resin reservoir 23, upper and lower nozzles 24 and 25, and a valve (not shown) that can be opened and closed. The structure of the material to be placed in the mold and molded was as shown in FIG. 2.

That is, in FIG. 2, 33 is a separation layer,
This is a tube made of the nonwoven fabric of Example 1 with a basis weight of 40 g/m2, with one end closed. The resin mixture 34 was added to this and the other end was closed. Specifically, 100 parts of Expancel DU461, which is an expandable particle, and 100 parts of glass hollow particles M28, manufactured by Asahi Insulator Co., Ltd., were added to a nonwoven fabric tube with one end closed. Part 5
00 parts of epoxy resin was mixed and the expandable particles were fixed on the surface of the glass hollow particles, and the other end was closed. The epoxy resin used was “Epicoat 1001” 70 manufactured by Yuka Shell Co., Ltd.
30 parts of "Epicote 834" were added and mixed at 80° C., and 30 parts of phthalic anhydride and 1.5 parts of 2-methylimidazole were further added thereto. The epoxy resin was mixed with the expandable particles while it was still melted. This (bagged mixture) was laminated with a carbon fiber and glass fiber braid that would become the reinforcing fiber sheet 32. The carbon fiber blades are Toray's "Trading Cards" T-3964 and T-3484, and the glass fiber blades are Atkins &Pierce's"Atkins&Pierce"#9273, which are T-3484, #9273 and T-3964 were stacked in this order. This laminate was covered with a tube made of the stretchable nonwoven fabric with a basis weight of 120 g/m 2 used in Example 1, which served as the breathable sheet 31, and both ends were closed.

[0044] This was placed in a mold. At this time, the end of the breathable sheet 31 was sandwiched between the molds and led to the air/resin reservoir 23. The mold was then closed and epoxy resin was injected into the mold. As an epoxy resin, "Epicote 807" by Yuka Shell Co., Ltd. and a curing agent "Epomate YLH-006" were used in one part.
A mixture of 0.00 parts and 31 parts was used. The resin was injected through the lower nozzle 25 and exhausted through the upper nozzle 24. After confirming that the resin overflows from the upper nozzle 24 and is full, close each nozzle 24 and 25, and heat the mold to 105°C one after another.
heated to. The epoxy resin begins to harden, and at the same time the expandable particles expand, and the resin passes through the nonwoven fabric 33 to reach the reinforcing fiber sheet 32 made of the laminated braid described above, and further reaches the nonwoven fabric 31, which becomes the breathable sheet, and part of the resin passes through 31. The air/resin reservoir 23 was reached. The air in the mold, including the air in the nonwoven fabric and reinforcing fiber sheet layers, was discharged through the resin path to 23 prior to the resin. Further, the final remaining amount was discharged to 23 along with the resin. A part of the resin accumulated on the inside of the breathable sheet 31 and the outside of the separation layer 33 at both the upper and lower ends of the mold, and was cured. Cut off both the upper and lower ends to make the surface layer F.
A good rod-shaped molded product having RP and a core made of syntactic foam was obtained.

In this example, most of the resin that reaches the reinforcing fiber sheet layer 32 is the melted mixed epoxy resin wrapped in the separation layer 33, and the resin injected later is the resin that reaches the outermost layer of the breathable sheet 31. It enters through the former and is one with the former. This resin is used to form the skin layer and correct the amount of mixed epoxy resin inside.

[0046]

[Embodiment 3] This example is a prototype of an air spoiler for an automobile.

First, glass fibers are knitted,
A fibrous reinforcing material (preform) with an external shape similar to that of an air spoiler was prepared. In a separately prepared bag-shaped separation layer (the same thin non-woven fabric as in Examples 1 and 2), expandable particles "Expancel 461" and epoxy resin ("Epicoat 807"/"Epomate" used in Example 1) were placed. Y
LH-006 mixture) was added, and then the required number of bags with their entrances sealed were placed inside the above fibrous reinforcing material and the openings were sewn together. Furthermore, a blade tube structure (blade tubes arranged in parallel and glued together) whose inside is reinforced with a U-shaped resin molding is applied to the entire length of the air spoiler in the longitudinal direction on the side opposite to the skin surface. A bag-shaped stretchable non-woven fabric that serves as a breathable sheet was placed to cover the area. As a result, the braided tube structure is sandwiched between the fibrous reinforcement (preform) and the breathable sheet (non-woven fabric), with the longitudinal upper part touching the fibrous reinforcement (preform) and the longitudinal lower part and both ends. will be in contact with the breathable sheet (nonwoven fabric). This breathable sheet was the same as the thick nonwoven fabric used in Examples 1 and 2, and was permeable to epoxy resin.

The unexpanded molding structure thus prepared was set in the lower die of a mold. After the upper and lower molds were clamped, steam was passed through the jacket of the mold and rapidly heated to approximately 80° C. to expand the volume of the expandable particles and harden the resin. Hold the mold for a specified period of time (about 1 hour), replace the steam in the jacket of the mold with cooling water, cool it down sufficiently, and then open the mold.
I was able to obtain a prototype of the air spoiler.

[Brief explanation of the drawing]

FIG. 1 is a simplified cross-sectional view showing an example of the configuration of a mold and a molding material placed in the mold when manufacturing a model of an automobile trunk lid according to the present invention.

FIG. 2 is a simplified cross-sectional view showing an example of the configuration of a mold and a molding material placed in the mold when producing a rod-shaped molded product according to the present invention.

[Explanation of symbols]

1 Upper mold 2 of trunk lid molding mold
Lower mold of trunk lid mold 3 Air/resin reservoir provided in the mold 4 Air vent provided in the upper mold of the mold 5 Air vent provided in the lower mold of the mold 6 Exhaust hole provided in the mold 11 Ventilation Sheet (closely woven nonwoven fabric) 12 Reinforcing fiber sheet (glass cloth) 13 Separation layer (coarse nonwoven fabric) 14 Mixture of expandable particles and resin 21 Left side of a two-part mold for molding a rod-shaped product 2
2 Right side 23 of the two-part mold for molding rod-shaped products
Air/resin reservoir 24 provided in the mold Upper nozzle 25 provided in the mold Lower nozzle 31 provided in the mold Breathable sheet (closed non-woven fabric) 32 Reinforcement fiber sheet (laminated blade) 33 Separation layer ( 34 Mixture of expandable particles and resin

Claims (6)

[Claims] 1. A method for producing an integrated composite molded article having a surface layer made of a thermosetting resin phase containing a fibrous reinforcing material and a core made of the resin phase containing expanded particles, comprising: (a) An expandable mold having pores on the inner wall side of a substantially closed molding mold that allow gas to flow and allow thermosetting resin to penetrate but prevent its free flow. (b) positioning expandable particles and a thermosetting resin or its precursor at a position opposite to the inner wall of the mold of the fibrous reinforcing material; (c) Expanding the expandable particles by raising the temperature to cause volumetric expansion of the aggregate of the particles; (d) The volumetric expansion of (c) causes the breathable sheet and the fibrous reinforcing material to expand. While pressing against the inner wall surface of the mold, the thermosetting resin or its precursor penetrates into the fibrous reinforcing material, and the gas components in the mold space are discharged from the air-permeable sheet to the outside of the space. , a thermosetting resin or its precursor is present inside the fibrous reinforcing material and between the expandable particles; (e) the thermosetting resin or its precursor is then cured to complete solidification; 1. A method for producing a composite molded article, comprising the steps of: (f) removing the composite molded article thus obtained from the mold. [Claim 2] A member constituting an air trap is provided between the breathable sheet and the fibrous reinforcing material or in a region that will become the core, to trap gas components in the space and excess thermosetting resin or its precursor. 2. The manufacturing method according to claim 1, wherein the material is stored inside the member. 3. The manufacturing method according to claim 1 or 2, wherein the breathable sheet is installed in the mold with the assumption that it will cover the entire outer surface of the composite molded product. . 4. The manufacturing method according to claim 1, wherein the breathable sheet is in the form of a bag-like structure. 5. The expandable particle aggregate further contains non-expandable hollow/expanded particles and/or a lightweight material having a specific gravity of 0.5 or less. Manufacturing method described. 6. Separation between the phase containing expandable particles and the fibrous reinforcing material that substantially does not allow the expandable particles to pass through, but allows the flowable thermosetting resin or its precursor to pass through during molding. The manufacturing method according to any one of claims 1 to 5, wherein a layer is provided.