Method for manufacturing molded body and structure using shellac

Abstract

To provide a method for manufacturing a molded body and structure using shellac which can easily and appropriately manufacture a molded body such as a porous molded body using shellac.SOLUTION: The method for manufacturing a molded body using shellac includes the steps of: mixing metal powder with a shellac solution in which shellac is dissolved in alcohol to obtain a shellac mixture fluid; placing the shellac mixture fluid into a mold; and vaporizing the alcohol in the shellac mixture fluid to obtain a molded body. Porosity is produced by heating at a temperature equal to or higher than the boiling point of alcohol to boil the alcohol, or by heating at a temperature equal to or higher than the heat curing temperature of shellac to perform heat curing in a suspended state.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a method for producing molded bodies and structures using shellac, which is simpler and has a higher degree of freedom than metal materials and enables the production of molded bodies or structures such as porous molded bodies. [Background technology]

[0002] Shellac, a natural resin, is soluble in alcohol but insoluble in other organic solvents such as toluene, and has traditionally been used as an ink binder and a moisture-proofing agent for pharmaceuticals and food.

[0003] Also, as a conventional method for manufacturing a porous metal molded body, a method for manufacturing a porous metal material based on aluminum or an aluminum alloy or other metal or alloy has been proposed, in which at least one type of spacer resin is covered with at least one type of base metal, which are connected so that resin or voids are arranged at the connecting parts, and after compression molding, the spacer is removed by thermal decomposition or dissolution, and the metals are joined together by sintering, diffusion bonding, adhesion, or a similar joining method (Patent Document 1). According to this method, it is possible to manufacture a porous metal material in which the size and distribution of voids and the thickness of the matrix wall are controlled, the porosity is controlled, and holes in the wall of the base material are minimized to have no open holes on the surface, or the size and shape of the communicating holes are controlled. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2004-292888 A (Page 1) Summary of the Invention [Problem to be solved by the invention]

[0005] The problem to be solved in the method for producing molded bodies and structures using shellac is that, although shellac has been conventionally used as an ink binder and a moisture-proofing agent for pharmaceuticals and foods, there has been no proposal for using shellac to easily and appropriately produce molded bodies such as porous molded bodies.

[0006] Therefore, an object of the present invention is to provide a method for producing molded bodies and structures using shellac, which can easily and appropriately produce molded bodies such as porous molded bodies by using shellac. [Means for solving the problem]

[0007] In order to achieve the above object, the present invention has the following configuration. According to one embodiment of the method for manufacturing a molded body using shellac of the present invention, the method includes the steps of: mixing a metal powder with a shellac solution in which shellac is dissolved in alcohol to obtain a shellac mixed fluid; pouring the shellac mixed fluid into a production mold; and obtaining a molded body by evaporating the alcohol content of the shellac mixed fluid.

[0008] In addition, according to one embodiment of the method for producing a molded body using shellac according to the present invention, pores can be generated by heating the shellac at a temperature equal to or higher than its boiling point to boil the alcohol, or by heating the shellac at a temperature equal to or higher than its heat-curing temperature to heat-cur it in a suspended state.

[0009] In addition, one embodiment of the method for producing a molded body using shellac according to the present invention is characterized in that it includes the steps of: attaching a shellac solution in which shellac is dissolved in alcohol to the periphery of a model of a molded product made of expanded polystyrene or a model of a molded product produced by a 3D printer; attaching sand or metal powder as aggregate to the shellac solution attached to the model of the molded product in the previous step; and evaporating the alcohol content of the shellac solution and hardening it so that it is reinforced by the sand or metal powder, thereby obtaining a molded body as a mold for the molded product.

[0010] Furthermore, one embodiment of the method for producing a molded body using shellac according to the present invention can be characterized in that it includes, as a step before or after the step of obtaining a molded body as a mold for a molded product using the shellac, a step of attaching a lost foam mold wash used when producing castings by the lost foam method to the periphery of a model of a molded product made of expanded polystyrene or a model of a molded product produced by a 3D printer, and a step of attaching sand or metal powder as aggregate to the lost foam mold wash attached to the model of the molded product in the previous step.

[0011] Furthermore, according to one embodiment of the method for producing a molded body using shellac according to the present invention, at least some of the steps for obtaining a molded body as a molded product die can be performed multiple times.

[0012] In addition, according to one embodiment of the method for producing a molded body using shellac of the present invention, after obtaining a molded body as a mold for the molded product, a structure as a casting mold is obtained using dry sand or CO2 sand as a mold component for reinforcing the molded body.

[0013] In addition, according to one embodiment of the method for producing a molded product using shellac of the present invention, the model of the molded product is formed from a polystyrene material, and is taken out by dissolving it in a limonene solution or by melting it by heating, thereby obtaining a molded product as a mold for the molded product having a hollow space for forming the molded product.

[0014] Furthermore, according to one embodiment of the method for manufacturing a structure using shellac of the present invention, the method includes a step of using a shellac solution in which shellac is dissolved in alcohol, and utilizing the adhesive properties of the shellac to bond at least two of the adherends, which are punched metal, plate-shaped honeycomb, metal members other than the punched metal or plate-shaped honeycomb, glass wool, carbon fiber, and a molded body formed by mixing the shellac and metal powder, thereby bonding the adherends into a plurality of layers.

[0015] In addition, according to one embodiment of the method for manufacturing a structure using shellac of the present invention, the method can be characterized by including a step of obtaining a shellac mixed fluid by mixing a metal powder with a shellac solution in which the shellac is dissolved in alcohol, a step of laminating the adherend members together using the shellac mixed fluid as an interlayer adhesive, and a step of adhering multiple metal plates in a stacked state by evaporating the alcohol content of the shellac mixed fluid. Effect of the Invention

[0016] According to the method for producing molded bodies and structures using shellac of the present invention, it is possible to obtain a particularly advantageous effect that by using shellac, it is possible to simply and appropriately produce molded bodies such as porous molded bodies and structures that are lightweight and have excellent heat insulating properties and sound absorbing properties. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, examples of the method for producing a molded body and a structure using shellac according to the present invention will be described.

[0018] The method for producing a molded body using shellac according to the present invention includes the steps of: mixing a metal powder with a shellac solution in which shellac is dissolved in alcohol to obtain a shellac mixed fluid; placing the shellac mixed fluid in a production mold; and evaporating the alcohol content of the shellac mixed fluid to obtain a molded body. As the metal powder, for example, aluminum powder is used, but the present invention is not limited to this, and powders of other metals can be used. As the shellac solution, for example, one diluted with 75% alcohol concentration can be used.

[0019] According to the method for producing a molded body using shellac of the present invention, the metal powder serves as an aggregate and the shellac functions as a binder, thereby providing the particularly advantageous effect of enabling a molded body to be produced simply and appropriately compared to, for example, a case in which a molded body is produced using only a metal material.

[0020] Shellac is a natural resin, and its properties are as follows: specific gravity: 1.02-1.12, specific heat: 0.53 (0°C), softening point: 70-80°C, acid value: 60-80, saponification value: 200-260, iodine value: 15-30 (Wiss-Tin method), heat curing time: 2-6 minutes (JIS K5909 170°C), volume resistivity: 1015-1016 Ω·cm, dielectric constant: 3.5-4.0, electrical insulation strength: 40-80 kV / mm, SP value: 12.5±2.0.

[0021] In addition, as an example of a method for producing a molded body using shellac according to the present invention, the process for vaporizing the alcohol content of the shellac mixed fluid can include a process for generating pores by heating the fluid at a temperature equal to or higher than the boiling point of the alcohol to boil the alcohol, or by heating the fluid at a temperature equal to or higher than the heat-curing temperature of the shellac to heat-cure the shellac in a suspended state.

[0022] According to this, the method for producing a molded body using shellac according to the present invention is a method for bonding a metal material (powder) with a resin binder, and has the special advantageous effect of not requiring large-scale equipment.In contrast, porous metals are generally obtained by a method using molten metal (metal melting) or fused metal (sintering) by heat, which requires large-scale equipment and results in high production costs.

[0023] Shellac is a natural resin with a wide molecular weight distribution, from low to high molecular weight, and its thermosetting property does not reach the final hardening point all at once, but can be adjusted to any hardening state. In other words, since the polymerization by thermosetting also occurs gradually, it is very different from synthetic resins, which harden all at once, and the degree of hardening can be adjusted by specifying the heating temperature and time. Another major feature of shellac resin is that it melts once before being thermoset.

[0024] Next, specific examples of the manufacturing method of a molded body using shellac will be explained below, divided into the cases of dense and porous molded bodies. Basically, a natural resin called shellac is used as a binder for metal powder, and a shellac solution diluted with, for example, 75% alcohol can be used, in which the aluminum powder and shellac are suspended in the alcohol to form a slurry. If more alcohol than necessary evaporates, the shellac begins to harden.

[0025] The manufacturing method for dense molds (dense moldings) is to place the mold containing the shellac mixed fluid in the process of pouring the fluid into the mold as described above into an oven, where the alcohol is evaporated in the oven. For example, the oven temperature is set to 70°C. In this way, the alcohol is evaporated at a low temperature below the boiling point of alcohol, resulting in a dense material. In other words, by gently evaporating the alcohol, the weight of the aluminum itself creates a dense material without porosity.

[0026] Also, by evaporating the alcohol below its boiling point, the shellac solidifies and bonds the aluminum powder, as mentioned above. Shellac in this state can be turned back into a slurry material by utilizing its thermoplastic properties at 70℃ to 80℃. In other words, due to its properties of both thermoplasticity and thermosetting, the material can be recycled before it is thermally hardened.

[0027] In the manufacturing method of the porous mold (porous molded body), after the step of putting the shellac mixed fluid into the production mold as described above, the production mold in which the shellac mixed fluid has been put is put into an oven, and the oven is set to a temperature of, for example, 170°C and heated for, for example, 30 minutes. This makes it possible to obtain a molded body with generated pores (in this embodiment, a molded body with a 10 cm square and a thickness of about 2 cm). That is, since the thermal hardening temperature of shellac is 170°C, it is thermally hardened in a suspended state by heating at a temperature higher than that. The metal that has solidified in this state becomes porous (see FIG. 2). It is presumed that the reason why the porous molded body is formed in this way is that the alcohol content boils when the temperature is suddenly raised to a high temperature, and the vaporized gas makes it porous. In other words, the alcohol content containing shellac is boiled, and the vaporized gas generates the pores. It was visually confirmed that the shellac was boiling during heating. The heating time varies depending on the size and shape of the molded body, the size of the oven, the preheating conditions, etc., and for example, for a small heating object, a porous molded body could be obtained in about 5 minutes.

[0028] Next, the affinity of the molded body using the above-described shellac with metals will be described.

[0029] Experiments were conducted on the bonding properties of the shellac with gray cast iron, stainless steel, and steel as examples of metal materials. When the shellac mixed fluid that forms the shellac-based molded body was brought into contact with the metals and thermally cured at 170°C, in each case the shellac-based molded body and the metal materials bonded in such a way that they could not be released from the mold. This confirmed that shellac, being a natural resin, easily bonds with natural substances and has good affinity. Fluorine and silicone are suitable release agents for the mold.

[0030] The above manufacturing method does not require metal melting equipment, and an oven at about 200°C is all that is needed to easily produce a molded body using shellac. In other words, according to the present invention, no large-scale equipment is required. In addition, by controlling the temperature and time, it is possible to produce either porous or dense materials. Shellac is a natural resin that is not produced from fossil fuels, and is therefore environmentally friendly as a biomass. Furthermore, because shellac is a natural resin, it does not produce harmful gases even when heated.

[0031] Furthermore, being a natural resin, it has a high affinity with natural mineral substances (iron, stainless steel, glass, etc.). By utilizing this property, when a molded body (such as an aluminum porous metal molded body) of a required thickness using shellac is sandwiched between metal plates such as steel plates, the two plates are bonded together using shellac as an adhesive, and a lightweight soundproofing material, vibration damping material, and heat insulating material that combine sound insulation and attenuation properties can be manufactured. In addition, this metal plate can be made into a perforated plate (punched metal).

[0032] Next, a method of applying the method for producing a molded body using shellac according to the present invention to the production of a molded product (casting mold or resin molding mold) will be described below.

[0033] The method for manufacturing a molded body (such as a mold) using shellac according to the present invention is characterized in that it includes the steps of: applying a shellac solution, in which shellac is dissolved in alcohol, to the periphery of a model of a molded product made of expanded polystyrene or a model of a molded product manufactured by a 3D printer; applying sand or metal powder as aggregate to the shellac solution applied to the model of the molded product in the previous step; and evaporating the alcohol content of the shellac solution and hardening it so that it is reinforced by the sand or metal powder, thereby obtaining a molded body (such as a mold) as a mold for a molded product.

[0034] In this case, the process includes a step of attaching a lost foam coating agent used when producing castings by the lost foam method to the periphery of a model of a molded product made of expanded polystyrene or a model of a molded product produced by a 3D printer, as a step before or after the step of obtaining a molded body as a mold for a molded product by the shellac, and a step of attaching sand or metal powder as an aggregate to the lost foam coating agent attached to the model of the molded product in the previous step, thereby obtaining a molded body (mold) as a mold for a molded product that is more resistant to collapse and has a stronger and more stable structure. As the lost foam coating agent, for example, Styromol 144 from Foseco Japan Limited (6-1-10 Miyukidori, Chuo-ku, Kobe) can be used.

[0035] For example, in the case of a model of a molded product made of expanded polystyrene, when the model of the molded product is dissolved and fluidized using a solvent such as a limonene solution as described below and then discharged, the inner surface of the mold formed by the lost foam wash becomes rough, and the sand or metal powder as aggregate may easily peel off. Therefore, in order to reinforce the inner surface of the mold, the inner surface of the mold may be coated with shellac by dipping the inner surface in the above-mentioned shellac solution or a mixed solution in which the shellac solution is mixed with sand, etc. In this way, the inner surface of the mold can be suitably coated with a thin layer of shellac, and the finish of the casting surface can be improved.

[0036] In addition, in the case of ordinary lost foam, expanded polystyrene (Styrofoam) is expanded 30 to 50 times, but in the case of the model of the molded product made of expanded polystyrene according to the present invention, the expansion rate can be lowered to make it denser. This allows the molded product (casting) to have a finely textured casting surface.

[0037] Furthermore, by performing at least some of the above-mentioned steps for obtaining a molded body as a molded product mold multiple times, it is possible to obtain a molded body (casting mold) as a mold for a molded product that is more stable, stronger, and less likely to crumble.

[0038] That is, as an example of a method for reinforcing the above-mentioned molded body, a process of attaching a shellac solution in which shellac is dissolved in alcohol to the periphery (surface) of a model of a molded product made of expanded polystyrene or a model of a molded product manufactured by a 3D printer, a process of attaching sand or metal powder to the shellac solution attached to the model of the molded product in the previous process, and a process of evaporating the alcohol content of the shellac solution and hardening it to a state reinforced by sand or metal powder can be performed multiple times to obtain a molded body as a mold for a molded product. Note that in the process of evaporating the alcohol content of the shellac solution and hardening it to a state reinforced by sand or metal powder, it is necessary to completely harden it in the last process of the multiple times, but in the processes up to that point, it is sufficient to harden the part of the film layer formed by the shellac liquid that is in contact with the original model so as not to deform, and it is not necessary to completely harden it. Similarly, the above-mentioned series of processes may be performed multiple times for the lost foam wash agent.

[0039] Furthermore, after obtaining a molded body as a mold for the molded product, a structure as a mold can be obtained using dry sand or CO2 sand as a mold component to reinforce the molded body, thereby obtaining a reinforced and stable structure (mold) as a mold for the molded product.

[0040] That is, one method of reinforcing the molded body (mold) includes a process in which a shellac solution in which shellac is dissolved in alcohol is applied around the model and sand is applied to form a film-like molded body made of the shellac solution and sand, and the film-like molded body is then buried in CO2 sand so as to be backed by the self-hardening CO2 sand and the CO2 sand is hardened, thereby obtaining a molded body (mold) that serves as a mold for a molded product backed up by CO2 sand.

[0041] According to the above-mentioned method for producing a molded body using shellac, a molded body can be easily formed as a mold for a molded product such as a casting mold. That is, this molded body can be suitably used as a mold for metal casting or a mold for resin molding. This makes it suitable for small-lot production of a wide variety of products. In addition to polystyrene, which will be described later, a model of a molded product such as a casting produced by a 3D printer can also be formed using a wax resin for a 3D printer used in lost wax casting.

[0042] As an example of a method for manufacturing a molded body (mold) using shellac, a prototype (model) of the casting is formed from polystyrene material and removed by dissolving it in a limonene solution or by melting it by heating, thereby obtaining a mold with a hollow space in which the casting is formed.

[0043] According to this method, a mold having a hollow space in which a casting is formed can be easily and rationally formed. For example, the method can include the following steps. First, a solvent such as a limonene solution is poured into a polystyrene model (master model) to swell and dissolve it. The dissolved, paste-like polystyrene model is removed from the mold. After that, or without carrying out a step using a solvent such as the limonene solution, the polystyrene model is heated to melt, fluidize, and flow out. As a result, molten metal can be poured into the space created in the mold using shellac to manufacture (cast) a casting. In the case of a model of a molded product made of expanded polystyrene, the model of the molded product can be appropriately dissolved, fluidized, and discharged using a heated limonene solution.

[0044] Specific process examples of the above embodiment are described below. Note that, although the following describes an example using a model of a molded product manufactured by a 3D printer, the present invention is not limited to this, and it goes without saying that a model of a molded product made of expanded polystyrene (manufactured by the same process as a model using the lost foam method) may also be used. 1) Create a model (prototype) using polystyrene (PS) material using a 3D printer. 2) A model created by a 3D printer is thickly coated with the above-mentioned shellac solution and sand or metal powder to create a molded body (such as a mold) using shellac. As a method of coating, sand or the like can be sprinkled in a shower-like manner on a model to which the shellac solution has been attached by dipping, so that the sand or the like can be efficiently attached. In addition, as described above, before or after this process, it is preferable to perform a process of attaching a lost foam wash to the periphery of the model and a process of attaching sand or metal powder as aggregate to the lost foam wash. In this case, too, sand or the like can be sprinkled in a shower-like manner on a model to which the lost foam wash has been attached by dipping, so that the sand or the like can be efficiently attached. The above-mentioned process using the shellac solution or the lost foam wash can be performed once or twice to obtain an appropriate molded body, but may be appropriately repeated to obtain a molded body with higher reliability. 3) The 3D printer model (PS material) is dissolved in a solvent such as limonene solution and removed. Alternatively, the 3D printer model (PS material) is heated and melted to remove. For example, by heating to about 250°C, the 3D printer model (PS material) can be melted so that it flows out. 4) The 3D printer model (PS material) becomes hollow, and the hollow mold (thick coating) is buried in dry sand or backed up with CO2 sand as necessary. If the molded item formed from this mold is small, dry sand can be adequately backed up, and if it is large, CO2 sand can be used. Note that in the other method using CO2 sand mentioned above, if the molded item has a shellac coating backed up with CO2 sand, there is no need to bury it in dry sand. 5) Molten metal is poured into the hollow area to create a casting.

[0045] In the above embodiment, the polystyrene model is extracted by injecting a solvent such as limonene solution into the polystyrene model to melt it, or by heating and melting the polystyrene model, but since it takes time to melt the model, as a solution to this problem, the polystyrene model is made hollow and has the minimum wall thickness that allows the shape of the polystyrene model to be maintained. This makes it possible to shorten the dissolving time required to extract the polystyrene model.

[0046] In addition, when manufacturing a mold, the runner portion may be made in advance from polystyrene foam in a standard shape depending on the mold, and connected to a model formed by a 3D printer as described above. The portion made from polystyrene foam dissolves extremely easily in an organic solvent such as a limonene solution, so a mold having a hollow in which a casting is formed can be appropriately and easily manufactured. In addition, the molded body described above, which is made using a shellac mixed fluid obtained by mixing metal powder with the shellac solution described above, can be used as a core when manufacturing a molded product.

[0047] Next, a method for producing a structure using shellac, in which a structure in which a plurality of metal plates are bonded together in a stacked state, will be described.

[0048] This method for manufacturing a structure using shellac is characterized by including the steps of: mixing a metal powder with a shellac solution in which shellac is dissolved in alcohol to obtain a shellac mixed fluid; laminating metal plates together using the shellac mixed fluid as an interlayer adhesive; and bonding multiple metal plates in a stacked state by evaporating the alcohol content of the shellac mixed fluid.

[0049] According to this, a structure in which multiple metal plates are stacked can be easily provided by utilizing adhesion with shellac. In this structure in which multiple metal plates are stacked, the shellac-mixed fluid hardens between the layers of the metal plates and functions as an adhesive layer, and the thickness of the shellac-mixed fluid between the layers of the metal plates can be made sufficiently thinner than the thickness of the molded body using shellac as described above.

[0050] In addition, when the metal plate is a perforated plate or a low-height honeycomb plate, for example, perforated plates or plate-shaped honeycombs are stacked with their perforations shifted from each other, and the above-mentioned shellac mixed fluid is interposed between each layer, and the shellac mixed fluid is hardened to obtain a metal plate laminate (structure) in the form of a plurality of perforated plates stacked more firmly. That is, the shellac mixed fluid can enter the perforations of the perforated plate or honeycomb and harden, so that the bonding strength between the perforated plates can be increased. At this time, by heating the shellac mixed fluid so that pores are generated as described above, the perforated plates can be bonded to each other, and a lightweight structure can be obtained that can absorb and suppress vibrations and sounds by the porous structure. In addition, the shellac solution mainly enters and bonds the metal plates in the areas where the surfaces of the metal plates contact each other.

[0051] In addition, the method of manufacturing a structure using the adhesiveness of shellac is not limited to the above method, and includes a step of bonding at least two of the adherend members, which are punched metal, a plate-shaped honeycomb, a metal member other than the punched metal or the plate-shaped honeycomb, glass wool, carbon fiber, and a molded body prepared by mixing the shellac and metal powder, into a plurality of layers by using a shellac solution in which shellac is dissolved in alcohol and the adhesiveness of the shellac is utilized. The two adherend members may be combinations of various members, or may be members of the same type, such as two sheets of punched metal. This allows for the rational manufacture of a lightweight structure and a structure that can improve heat insulation and sound absorption.

[0052] Furthermore, the above-mentioned structures using shellac are not limited to shapes in which planar members (bonded members) are bonded together in layers, but also include structures formed in layers by bonding together curved or bent planar members, and structures formed in a sandwich-like layered structure by sandwiching and bonding a bonded member between a pair of planar members.

[0053] Although the present invention has been described above in various preferred embodiments, the present invention is not limited to these embodiments, and it goes without saying that many modifications can be made without departing from the spirit of the invention.

Claims

1. A method for producing a molded body using shellac, comprising the steps of: mixing a metal powder with a shellac solution in which shellac is dissolved in alcohol to obtain a shellac mixed fluid; placing the shellac mixed fluid in a production mold; and obtaining a molded body by evaporating the alcohol content of the shellac mixed fluid.

2. A method for producing a molded body using shellac according to claim 1, characterized in that pores are generated by heating the shellac at a temperature equal to or higher than the boiling point of the alcohol to boil the alcohol, or by heating the shellac at a temperature equal to or higher than its heat-curing temperature to heat-cur it in a suspended state.

3. A method for producing a molded body using shellac, comprising the steps of: applying a shellac solution in which shellac is dissolved in alcohol to the periphery of a model of a molded product made of expanded polystyrene or a model of a molded product produced by a 3D printer; applying sand or metal powder as aggregate to the shellac solution applied to the model of the molded product in the previous step; and evaporating the alcohol content of the shellac solution and hardening it so that it is reinforced by the sand or metal powder, thereby obtaining a molded body as a mold for a molded product.

4. The method for producing a molded body using shellac according to claim 3, characterized in that it includes, as a step before or after the step of obtaining a molded body as a mold for a molded product using the shellac, a step of attaching a lost foam mold wash used when producing castings by the lost foam method to the periphery of a model of a molded product made of expanded polystyrene or a model of a molded product produced by a 3D printer, and a step of attaching sand or metal powder as aggregate to the lost foam mold wash attached to the model of the molded product in the previous step.

5. 5. The method for producing a molded body using shellac according to claim 4, wherein at least some of the steps for obtaining the molded body as the molded product are carried out a plurality of times.

6. After obtaining a molded body as a mold for the molded product, dry sand or CO is used to reinforce the molded body. ２ 6. The method for producing a molded body using shellac according to claim 5, wherein the structure as a mold is obtained using sand.

7. The method for producing a molded product using shellac according to any one of claims 3 to 6, characterized in that the model of the molded product is made of a polystyrene material, and is taken out by dissolving it in a limonene solution or by melting it by heating, thereby obtaining a molded product as a mold for a molded product having a hollow space for forming the molded product.

8. A method for manufacturing a structure using shellac, comprising a step of bonding at least two of the following adherends into a plurality of layers: a punched metal, a plate-shaped honeycomb, a metal member other than the punched metal or the plate-shaped honeycomb, glass wool, carbon fiber, or a molded body formed by mixing the shellac and metal powder, using a shellac solution in which shellac is dissolved in alcohol and utilizing the adhesive properties of the shellac to bond the adherends together.

9. A method for manufacturing a structure using shellac as described in claim 8, characterized in that it includes the steps of: mixing a metal powder with a shellac solution in which the shellac is dissolved in alcohol to obtain a shellac mixed fluid; laminating the bonded members together using the shellac mixed fluid as an interlayer adhesive; and bonding multiple metal plates in a stacked state by evaporating the alcohol content of the shellac mixed fluid.