Method for producing molded body and structure using shellac

Abstract

The present invention provides a method for producing a molded body using shellac whereby it is possible to easily and suitably produce a molded body such as a porous molded body, a molded body serving as a mold for a molded article, or the like by using shellac. The method is characterized in that a molded body serving as a mold for a molded article is obtained as a result of the inclusion of the following steps: a step in which a shellac solution (30) in which shellac is dissolved in alcohol is made to adhere to the periphery of a model (10) of a molded article made from expanded polystyrene or a model (11) of a molded article produced by a 3D printer; a step in which sand or a metal powder (35) is made to adhere as an aggregate to the shellac solution (30) made to adhere to the model of the molded article in the previous step; and a step in which the alcohol portion of the shellac solution (30) is evaporated and the result is cured so as to be reinforced by the sand or metal powder (35).

Description

Method for manufacturing molded bodies and structures using shellac

[0001] This invention relates to a method for producing molded bodies and structures using shellac, which is simpler and more flexible than molding using only metal materials, and can produce molded bodies or structures such as molded bodies used as molded product molds and porous molded bodies.

[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 products.

[0003] Furthermore, a conventional method for producing a porous metal molded body has been proposed, which involves producing a porous metal material based on aluminum or an aluminum alloy or other metal or alloy, in which at least one type of base metal is coated around at least one type of spacer resin, and the resulting materials are connected so that resin or voids are disposed at the connecting portions, and then compression-molded, after which the spacer is removed by thermal decomposition or dissolution, and the metals are joined together by sintering, diffusion bonding, adhesive bonding, or a similar joining method (Patent Document 1). This method allows for the production of 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 base wall are minimized to eliminate open pores on the surface, or the size and shape of the interconnecting pores are controlled.

[0004] JP 2004-292888 A (page 1)

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

[0007] To achieve the above object, the present invention has the following configuration: According to one embodiment of the method for producing a molded body using shellac of the present invention, the method 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 produced by a 3D printer; applying sand or metal powder as aggregate to the shellac solution that has been applied to the model of the molded product in a 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.

[0008] Furthermore, one embodiment of the method for producing a molded body using shellac according to the present invention can be characterized by including, 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 molded product model made of expanded polystyrene or a molded product model 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 molded product model in the previous step.

[0009] 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 the molded body as the molded product die can be performed multiple times.

[0010] 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, dry sand or CO ２ It can be characterized in that sand is used to obtain a structure as a mold.

[0011] Furthermore, according to one embodiment of the method for producing a molded article using shellac according to the present invention, the model of the molded article is formed from a polystyrene material, and is removed by dissolving it in a limonene solution or by heating it to melt it, thereby obtaining a molded article serving as a mold for the molded article having a hollow space for forming the molded article.

[0012] In addition, one embodiment of the method for manufacturing 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 into a manufacturing mold, and evaporating the alcohol content of the shellac-mixed fluid to obtain a molded body, and is characterized in that the alcohol is boiled by heating at a temperature above the boiling point of the alcohol, thereby generating pores.

[0013] In addition, 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, placing the shellac-mixed fluid into a manufacturing mold, and evaporating the alcohol content of the shellac-mixed fluid to obtain a molded body, and is characterized in that by heating at a temperature above the boiling point of the alcohol and above the thermal hardening temperature of the shellac, the alcohol is boiled and the shellac is thermally hardened in a suspended state, thereby generating pores.

[0014] Furthermore, according to one embodiment of the method for manufacturing a structure using shellac according to 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 adherend members, which are perforated metal, a plate-shaped honeycomb, a metal member other than the perforated metal or the plate-shaped honeycomb, glass wool, carbon fiber, or a molded body formed by mixing the shellac and metal powder, to form a plurality of layers, and the method can be characterized by including a step of mixing metal powder into the shellac solution to form a shellac-mixed fluid, a step of stacking the adherend members together using the shellac-mixed fluid as an interlayer adhesive, and a step of evaporating the alcohol content of the shellac-mixed fluid to bond the plurality of adherend members in a stacked state.

[0015] The method for producing molded bodies and structures using shellac of the present invention has the particularly advantageous effect of enabling the use of shellac to easily and appropriately produce molded bodies such as molded bodies used as molded product molds, porous molded bodies, and lightweight structures that are excellent in heat insulation and sound absorption properties.

[0016] 5 is a cross-sectional view showing an example of a molded body used as a mold for a molded product using shellac according to the present invention, schematically illustrating a state in which it has been formed on a model of a molded product made from expanded polystyrene. FIG. 6 is a cross-sectional view showing an example of a model of a molded product made from expanded polystyrene according to the present invention. FIG. 7 is a cross-sectional view showing an example of a process in which a lost foam mold wash is attached to the model of the molded product of FIG. 2. FIG. 8 is a cross-sectional view showing an example of a process in which sand or metal powder is attached to the example of FIG. 3. FIG. 9 is a cross-sectional view showing an example of a process in which a shellac solution is attached to the example of FIG. 4. FIG. 10 is a cross-sectional view showing an example of a process in which sand or metal powder is attached to the example of FIG. 5. FIG. 11 is a cross-sectional view showing an example of a molded body used as a mold for a molded product using shellac according to the present invention, schematically illustrating a state in which it has been formed on a model of a molded product produced with a 3D printer. FIG. 12 is a cross-sectional view showing an example of a molded body used as a mold for a molded product using shellac according to the present invention, schematically illustrating a state in which the model of the molded product is dissolved or fused and removed, forming a hollow in which a casting is formed.

[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; pouring the shellac-mixed fluid into a production mold; and evaporating the alcohol content of the shellac-mixed fluid to obtain a molded body. While aluminum powder is used as the metal powder, it is not limited thereto, and powders of other metals can also be used. Furthermore, a shellac solution diluted with, for example, 75% alcohol 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, which has the particularly advantageous effect of enabling a molded body to be produced more easily and appropriately than when molding is performed using only metal materials.

[0020] Shellac is a natural resin, and its properties are as follows: specific gravity: 1.02 to 1.12, specific heat: 0.53 (0°C), softening point: 70 to 80°C, acid value: 60 to 80, saponification value: 200 to 260, iodine value: 15 to 30 (Wissin method), heat curing time: 2 to 6 minutes (JIS K5909 170°C), volume resistivity: 1015 to 1016 Ω cm, dielectric constant: 3.5 to 4.0, electrical dielectric strength: 40 to 80 kV / mm, and 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 step of vaporizing the alcohol content of the shellac mixed fluid can include a step of boiling the alcohol by heating at a temperature above the boiling point of the alcohol, or of generating pores by heating at a temperature above the thermosetting temperature of the shellac to thermoset it in a suspended state.

[0022] According to this, the method for manufacturing a molded body using shellac according to the present invention is a method of bonding metal material (powder) with a resin binder, which has the special advantage of not requiring large-scale equipment.In contrast, porous metals are generally obtained by methods using thermal molten metal or fused metal (sintering), which require large-scale equipment and result in high manufacturing costs.

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

[0024] Next, specific examples of methods for manufacturing molded bodies using shellac will be described below, divided into dense and porous molded bodies. Basically, the natural resin shellac is used as a binder for metal powder. A shellac solution diluted with, for example, 75% alcohol can be used. The aluminum powder and shellac are suspended in the alcohol (e.g., ethanol) to form a slurry. When the alcohol evaporates beyond the required amount, the shellac begins to harden.

[0025] In the method for manufacturing a dense molded body, the mold containing the shellac-mixed fluid is placed in an oven during the process of pouring the shellac-mixed fluid into the mold as described above, and the alcohol is evaporated in the oven. For example, the oven temperature is set to 70°C. The alcohol is evaporated at a low temperature below the boiling point of the alcohol (e.g., ethanol), resulting in a dense material. In other words, by gently evaporating the alcohol, the weight of the aluminum creates a dense material without porosity.

[0026] Furthermore, by vaporizing the alcohol below its boiling point, the shellac solidifies and bonds to the aluminum powder, as mentioned above. Shellac in this state can be turned back into a slurry-like material by utilizing its thermoplastic properties at temperatures between 70 and 80°C. In other words, due to its properties of both thermoplasticity and thermosetting, the material can be recycled before it hardens.

[0027] As described above, the porous molded body is produced by placing the shellac-mixed fluid into a mold, followed by heating the mold containing the shellac-mixed fluid for, for example, 30 minutes at a temperature set to 170°C or higher. This results in a molded body with a porous structure (in this example, a molded body with a 10 cm square and a thickness of approximately 2 cm). Since the thermosetting temperature of shellac is 170°C, heating at temperatures above this temperature causes the shellac to thermoset in a suspended state. (The shellac is heated to a temperature range where it softens, and then further heated above the thermosetting temperature to thermoset in a suspended state.) It solidifies in this state, becoming porous. It is believed that the formation of the porous molded body occurs when the temperature is suddenly raised to a high temperature, causing the alcohol to boil and the vaporized gas to create the pores. In other words, boiling the shellac-containing alcohol generates the pores through the vaporized gas. During heating, the shellac was visually observed to be boiling. The heating time varies depending on the size and shape of the molded body, the size of the oven, the preheating conditions, etc. For example, for a small heating object, a porous molded body can 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 bondability of the shellac to gray cast iron, stainless steel, and steel as examples of metal materials. When the shellac-mixed fluid, which forms a molded body using shellac, was brought into contact with these metals and thermally cured at 170°C, in all cases, the shellac-mixed fluid bonded to the metal material in such a way that it 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 as mold release agents.

[0030] The above manufacturing method does not require metal melting equipment, and a molded body using shellac can be easily produced with an oven at approximately 200°C. In other words, the present invention does not require large-scale equipment. Furthermore, by controlling the temperature and time, it is possible to produce either porous or dense materials. For example, large pores can be formed by rapidly cooling the alcohol from a boiling state, while small pores can be formed by slowly cooling the alcohol from a boiling state. Furthermore, by rapidly raising the temperature above the thermosetting temperature of shellac, the boiling of the alcohol can be utilized to form larger pores. Shellac, a natural resin, is not derived from fossil fuels and is therefore environmentally friendly as a biomass. Furthermore, because shellac is a natural resin, it does not emit harmful gases even when heated. Regarding the metal powders mixed into the shellac solution, for example, when aluminum powder and copper powder are used to form a molded body, aluminum powder is lighter and therefore more likely to form pores, while copper powder is heavier and therefore more likely to settle, making it more difficult to form pores, assuming other conditions are the same.

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

[0032] Next, a method for 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 with reference to FIGS. 1 to 8.

[0033] The method for producing a molded body (such as a casting mold) using shellac according to the present invention is characterized by comprising the steps of: applying a shellac solution 30, in which shellac is dissolved in alcohol, to the periphery of a molded product model 10 (see FIG. 1) made of expanded polystyrene or a molded product model 11 (see FIG. 7) produced by a 3D printer; applying sand or metal powder 35 as aggregate to the shellac solution 30 that has been applied to the molded product model 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 casting mold) as a mold for the molded product.

[0034] In this case, the process includes, before or after the step of obtaining a molded body as a mold for a molded product using the shellac, a step of applying a lost foam mold wash 20 used in producing castings by the lost foam method to the periphery of a molded product model 10 made of expanded polystyrene or a molded product model 11 produced by a 3D printer, and a step of applying sand or metal powder 25 as aggregate to the lost foam mold wash 20 applied to the molded product model in the previous step, thereby obtaining a molded body (mold) as a mold for a molded product that is more resistant to collapse, strengthened, and stable. The examples in Figures 1 and 7 show a state in which the lost foam mold wash 20 is first applied to the molded product models 10 and 11, followed by the application of sand or metal powder 25, which is repeated twice, and then a shellac solution 30 is applied, followed by the application of sand or metal powder 35. Illustrating an example of the process in order, for example, in the case of forming one layer of lost foam mold wash 20 and one layer of shellac solution 30, the lost foam mold wash 20 is applied to a model 10 of a molded product made of expanded polystyrene (see FIG. 2) (see FIG. 3), followed by sand or metal powder 25 (see FIG. 4), the shellac solution 30 (see FIG. 5), and finally sand or metal powder 35 (see FIG. 6), as shown in Figures 2 to 6. As the lost foam mold wash, for example, Styromol 144 from Foseco Japan Limited (6-1-10 Miyuki-dori, Chuo-ku, Kobe) can be used.

[0035] Furthermore, for example, in the case of a molded product model made of expanded polystyrene, dissolving and fluidizing the molded product model using a solvent such as a limonene solution, as described below, and then discharging the molded product model, the inner surface of the mold formed by the lost foam wash may become rough, making the sand or metal powder aggregate more likely to peel off. Therefore, to reinforce the inner surface of the mold, the inner surface of the mold may be coated with shellac by immersing the inner surface in, for example, the aforementioned shellac solution or a mixed solution in which the shellac solution is mixed with sand or the like. This allows the inner surface of the mold to be suitably coated with a thin layer of shellac, thereby improving the finish of the casting surface.

[0036] Furthermore, while the expanded polystyrene (Styrofoam) used in ordinary lost foam molding is expanded 30 to 50 times, the expanded polystyrene molded product model of the present invention can utilize a denser material with a lower expansion rate, allowing for the finished molded product (casting) to have a finer surface.

[0037] Then, by performing at least some of the above-mentioned steps for obtaining a molded body as a mold for the molded product multiple times, a molded body (casting mold) as a mold for a molded product that is more resistant to crumbling and stronger and more stable can be obtained. Note that, since the lost foam mold wash is water-soluble, when the lost foam mold wash is applied to a model of a molded product and sand or metal powder is then applied, it is advisable to allow it to dry sufficiently and solidify before applying the shellac solution thereafter.

[0038] That is, one example of a method for reinforcing the molded body described above involves a series of steps: applying a shellac solution, in which shellac is dissolved in alcohol, to the periphery (surface) of a molded product model made of expanded polystyrene or a molded product model produced by a 3D printer; applying sand or metal powder to the shellac solution previously applied to the molded product model; and evaporating the alcohol content of the shellac solution to harden the shellac solution into a reinforced state with sand or metal powder. By performing this series of steps multiple times, a molded body can be obtained as a mold for a molded product. Note that in the step of evaporating the alcohol content of the shellac solution to harden the shellac solution into a reinforced state with sand or metal powder, complete hardening (solidification) is required in the final step of the multiple steps, but in the previous steps, it is sufficient to harden the film layer formed by the shellac solution to the extent that the portion in contact with the master mold does not deform; complete hardening is not necessary. Similarly, the series of steps may also be performed multiple times for the lost foam mold wash described above.

[0039] Furthermore, after obtaining a molded body as a mold for the molded product, dry sand or CO ２ By using sand to obtain a structure as a mold, it is possible to obtain a structure (mold) as a mold for a molded product that is reinforced and stable.

[0040] That is, one method for reinforcing the molded body (mold) is to apply a shellac solution, in which shellac is dissolved in alcohol, to the periphery of the model and to attach sand, etc., to form a film-like molded body made of the shellac solution and sand, etc., and then apply a self-hardening CO ２ To line the sand, ２ It is buried in sand and the CO ２ and hardening the sand, ２ A molded body (mold) serving as a molded product backed up by sand can be obtained.

[0041] According to the above-described 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 high-mix, low-volume production. Furthermore, models for molded products such as castings produced by 3D printers can also be formed using, for example, 3D printer wax resins used in lost-wax casting, in addition to polystyrene, as described below.

[0042] In another example of a method for manufacturing a molded body (mold) using shellac, a prototype (model) for the casting is formed from polystyrene and then removed by dissolving it in a limonene solution or by heating it to melt it, resulting in a mold having a cavity 40 for forming the casting, as shown in Figure 8. Limonene is a component found in large amounts in citrus peels and is a naturally occurring solvent that is environmentally friendly and highly safe. The process of removing the molded product models 10, 11 may be performed, for example, when the layered mold consisting of the highly heat-resistant lost foam wash 20 and sand or metal powder 25 is dried and formed, or when the mold is reinforced by adding an additional layer of shellac solution 30 and sand or metal powder 25, as shown in Figure 1 or Figure 7.

[0043] This method allows for the easy and efficient formation of a casting mold having a hollow for forming a casting. For example, the method may include the following steps: First, a polystyrene model (master) is injected with a solvent such as limonene solution to swell and dissolve it. The dissolved, paste-like polystyrene model is then removed from the mold. Subsequently, or without the step using a solvent such as limonene solution, the polystyrene model is heated to melt, fluidize, and flow out. Alternatively, the injection of the solvent such as limonene solution and the heating may be performed simultaneously. This allows for the production (casting) of a casting by pouring molten metal into the space (the hollow 40 for forming the casting) created in the shellac mold. In addition, in the case of a molded product made of expanded polystyrene, due to its low density (specific gravity), the molded product model can be more easily dissolved, fluidized, and discharged using a heated limonene solution.

[0044] Specific process examples of the above-described embodiments are described below. While the following describes an example using a molded product model produced with a 3D printer, the present invention is not limited to this, and a molded product model made of expanded polystyrene (manufactured using the same process as a lost foam model) may also be used. 1) A model (prototype) is created using polystyrene (PS) material with a 3D printer. 2) A molded body (such as a mold) is created using shellac by thickly coating the model created with the 3D printer with the aforementioned shellac solution and sand or metal powder. As a coating method, sand or the like can be showered onto the model to which the shellac solution has been applied by immersion, thereby efficiently adhering the sand or the like. Furthermore, before or after this process, as described above, a process of applying a lost foam mold wash to the periphery of the model and a process of applying sand or metal powder as aggregate to the lost foam mold wash may be performed. In this case, too, sand can be efficiently attached by showering it onto a model to which a lost foam wash has been applied by immersion or the like. The above-mentioned process using the shellac solution or lost foam wash can be performed once or twice to obtain an appropriate molded body, but it may be repeated as needed to obtain a more reliable molded body. 3) The 3D printer model (PS material) is extracted by dissolving it in a solvent such as a limonene solution. Alternatively, the 3D printer model (PS material) is extracted by heating and melting it. For example, by heating it 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 (a mold formed in a thick coating) is buried in dry sand as needed, or by using CO ２ For example, if the molded product formed by this mold is small, dry sand can be used to back it up, and if it is large, CO ２ Sand can be used. 5) Molten metal is poured into the hollow area to create a casting.

[0045] In the above-described embodiments, the polystyrene model is removed by injecting a solvent such as limonene solution into the model to melt it, or by heating and melting the model, but this takes time. To address this issue, as shown in FIG. 7 , the polystyrene model (e.g., a model 11 of a molded product produced by a 3D printer) is designed to have a hollow 11a and have the minimum wall thickness necessary to maintain the shape of the polystyrene model. This shortens the dissolution time required to remove the polystyrene model.

[0046] When manufacturing a casting mold, it is advisable to pre-fabricate the runner portion with a standard shape made of polystyrene foam and connect it to a model created using a 3D printer, as described above. The polystyrene foam portion dissolves extremely easily in organic solvents such as limonene solution, allowing for the appropriate and easy manufacture of a casting mold with a hollow space for forming the casting. Furthermore, the molded body described above, which is formed using the shellac-mixed fluid obtained by mixing metal powder with the shellac solution, can be used as a core when manufacturing a molded product.

[0047] Next, a method for manufacturing 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 together in a stacked state by evaporating the alcohol content of the shellac-mixed fluid.

[0049] This makes it possible to easily provide a structure in which multiple metal plates are stacked together using adhesion with shellac. In this structure in which multiple metal plates are stacked together, 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] Furthermore, when the metal plate is a perforated plate or a low-height honeycomb plate, for example, perforated plates or plate-like honeycombs can be stacked with their perforations offset, and the aforementioned shellac-mixed fluid can be interposed between each layer. Then, the shellac-mixed fluid can be hardened to obtain a metal plate laminate (structure) in which multiple perforated plates are stacked more firmly. That is, the shellac-mixed fluid can penetrate the perforations of the perforated plates or honeycombs and harden, thereby increasing the bonding strength between the perforated plates. In this case, by heating the shellac-mixed fluid to generate pores as described above, the perforated plates can be bonded together, and a lightweight structure can be obtained in which vibrations and sound can be absorbed and suppressed by the porous structure. Note that the shellac solution mainly penetrates and bonds the metal plate surfaces where they come into contact.

[0051] In addition, methods for manufacturing structures utilizing the adhesive properties of shellac are not limited to the above methods and include a process in which a shellac solution in which shellac is dissolved in alcohol is used to bond at least two adherends, including perforated metal, a honeycomb plate, a metal member other than the perforated metal or the honeycomb plate, glass wool, carbon fiber, and a molded body containing a mixture of shellac and metal powder, to form multiple layers. The two adherends may be combinations of various materials, or may be the same material, such as two perforated metal sheets. This method allows for the rational manufacture of lightweight structures and structures with improved thermal insulation and sound absorption. The structures described above also have the effect of blocking electromagnetic waves.

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

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

[0054] 10 Model of molded product made of expanded polystyrene 11 Model of molded product manufactured by 3D printer 11a Hollow 20 Lost foam coating agent 25 Sand or metal powder 30 Shellac solution 35 Sand or metal powder 40 Hollow where casting is formed

Claims

1. A method for producing a molded product 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 product as a mold for a molded product.

2. A method for producing a molded product using shellac as described in claim 1, characterized in that it includes, as a process before or after the process of obtaining a molded product as a mold for a molded product using the shellac, a process of applying a lost foam coating 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 process of applying sand or metal powder as aggregate to the lost foam coating applied to the model of the molded product in the previous process.

3. The method for producing a molded body using shellac according to claim 2, characterized in that at least some of the steps for obtaining the molded body as the molded product are carried out multiple times.

4. After obtaining a molded body as a mold for the molded product, dry sand or CO is used to reinforce the molded body. ２ 4. The method for producing a molded body using shellac according to claim 3, wherein the structure as a mold is obtained using sand.

5. A method for producing a molded product using shellac according to any one of claims 1 to 4, 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 the molded product having a hollow space for forming the molded product.

6. A method for producing a molded body using shellac, comprising the steps of: mixing a metal powder into 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 vaporizing the alcohol content of the shellac mixed fluid, characterized in that the alcohol is boiled by heating at a temperature equal to or higher than the boiling point of the alcohol, thereby generating pores.

7. A method for producing a molded body using shellac, comprising the steps of: obtaining a shellac mixed fluid by mixing a metal powder with a shellac solution in which shellac is dissolved in alcohol; pouring the shellac mixed fluid into a production mold; and obtaining a molded body by vaporizing the alcohol content of the shellac mixed fluid, characterized in that by heating at a temperature equal to or higher than the boiling point of the alcohol and equal to or higher than the heat-curing temperature of the shellac, the alcohol is boiled and the shellac is heat-cured in a suspended state, thereby generating pores.

8. A method for manufacturing a structure using shellac, comprising a step of bonding at least two of the bonded 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 formed 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 utilizing the adhesive properties of the shellac, the method for manufacturing a structure using shellac comprising a step of mixing metal powder into the shellac solution to obtain a shellac mixed fluid, a step of laminating the bonded members together using the shellac mixed fluid as an interlayer adhesive, and a step of vaporizing the alcohol content of the shellac mixed fluid to bond the plurality of bonded members in a layered state.

Images