Method for manufacturing a shaped body

Abstract

To provide a method capable of manufacturing a molded product having high dimensional accuracy without applying a mold-release agent nor cleaning a mold.SOLUTION: A manufacturing method of a molded product includes a mold packing step of vacuum-packing a mold having a recess with a resin film packing material and a casting solidification step of injecting slurry including ceramic powders and / or metal powders into the recess of the vacuum-packed mold and solidifying the slurry.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a molded body.

Background Art

[0002] As a method for manufacturing a molded body, a mold casting method, which is a kind of casting molding method, is known (for example, Patent Document 1). The mold casting method is a method for manufacturing a molded body by pouring a slurry containing a predetermined powder such as ceramic powder or metal powder, a reactant, a gelling agent, etc. into a mold and solidifying (curing) it in the mold.

[0003] In the mold casting method, conventionally, in order to facilitate the release of the molded body from the mold, a release agent is applied to the inner wall surface of the mold. Further, since residues of the slurry, the release agent, etc. adhere to the mold after the release of the molded body, it is necessary to wash the mold by immersing it in a cleaning liquid and brushing it (for example, Patent Document 2).

[0004] Here, a conventional molding process for manufacturing a molded body whose outer diameter dimensional accuracy is required is shown in FIG. 8. As shown in FIG. 8, first, a lower mold 110 and an upper mold 120 are prepared as components of the mold 100, and a release agent 130 is applied to each of the lower mold 110 and the upper mold 120 (P1). Next, the lower mold 110 and the upper mold 120 are assembled to produce the mold 100 (P2). Next, the slurry 140 is poured into the mold 100 and solidified (cured) (P3). Then, the molded body 150 can be obtained by releasing each mold (P4). And the lower mold 110 and the upper mold 120 after release are washed in order to manufacture the next molded body.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] In a conventional method for manufacturing a molded body by the mold casting method, it is necessary to apply a mold release agent to the mold before molding and to clean the mold after molding. However, the application of the mold release agent may cause uneven coating and difficulty in mold release. In addition, the cleaning of the mold may cause foreign matter to be mixed into the molded body due to insufficient cleaning of the mold. Therefore, it is difficult to use the same mold for molding products with different compositions. In addition, the equipment area for applying the mold release agent and cleaning the mold also increases. In particular, when molding products with different compositions, it is necessary to provide equipment for cleaning the molding die for each product. In addition, the application of the mold release agent and the cleaning of the mold take a long time, which causes a decrease in the productivity of the molded body. Furthermore, the application of the mold release agent and the cleaning of the mold require the use of chemicals, which also has a great impact on the manufacturing cost and the environmental load.

[0007] An object of the present invention is to solve the above problems, and in particular, to provide a method capable of manufacturing a molded body with good dimensional accuracy without applying a mold release agent and cleaning the mold.

Means for Solving the Problems

[0008] As a result of intensive studies to solve the above problems, the present inventor has found that by vacuum-packaging a mold having a concave portion with a resin film packaging material and performing molding using this vacuum-packaged mold, it is possible to omit the application of a mold release agent and the cleaning of the mold, and has completed the present invention. That is, the above problems are solved by the following present invention, and the present invention is as follows.

[0009] [1] A mold packaging step of vacuum-packaging a mold having a concave portion with a resin film packaging material, A casting and solidifying step of injecting and solidifying a slurry containing ceramic powder and / or metal powder into the concave portion of the vacuum-packaged mold including See, the resin film packaging material has thermoplasticity, mold release property, shape followability, and chemical resistance, A method for manufacturing a molded article.

[0010] [2] The method for manufacturing a molded article according to [1], further including a demolding step of repressing the inside of the resin film packaging material in which the mold is vacuum-packaged after the casting and curing step to demold the molded article.

[0011] [3] The method for manufacturing a molded article according to [1] or [2], wherein in the casting and curing step, after injecting the slurry, a lid material is disposed above the recess of the mold.

[0013] 4 The resin constituting the resin film packaging material is one or more selected from polyethylene resin, polypropylene resin, polystyrene resin, acrylonitrile styrene resin, ABS resin, vinyl chloride resin, polymethyl methacrylate resin, and polyethylene terephthalate resin, the method for manufacturing a molded article according to any one of [1] to 3 of the above.

[0014] 5 In the casting and curing step, the recess of the mold is maintained horizontally, the method for manufacturing a molded article according to any one of [1] to 4 of the above.

[0015] 6 The slurry further includes a reactant, a gelling agent, and a dispersion medium, the method for manufacturing a molded article according to any one of [1] to 5 of the above. [Advantages of the Invention]

[0016] According to the present invention, it is possible to provide a method capable of manufacturing a molded article with good dimensional accuracy without applying a release agent and cleaning the mold. [Brief Description of the Drawings]

[0017]

Figure 1

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Figure 8

Mode for Carrying Out the Invention

[0018] Hereinafter, embodiments of the present invention will be specifically described. The present invention is not limited to the following embodiments, and it should be understood that those obtained by appropriately making changes, improvements, etc. to the following embodiments based on the ordinary knowledge of those skilled in the art without departing from the gist of the present invention also fall within the scope of the present invention.

[0019] The method for manufacturing a molded body according to an embodiment of the present invention includes a mold packaging step and a casting and curing step. Further, the method for manufacturing a molded body according to an embodiment of the present invention can further include a mold release step after the casting and curing step. Each of these steps will be described.

[0020] <Mold Packaging Step> A schematic cross-sectional view for explaining the mold packaging step is shown in FIG. 1. As shown in FIG. 1, the mold packaging process is a process of vacuum-packaging a mold 10 having a recess 11 with a resin film packaging material 20. Specifically, in the mold packaging process, the mold 10 having the recess 11 and the resin film packaging material 20 are prepared. After the mold 10 is placed in the resin film packaging material 20, the air in the resin film packaging material 20 is removed, thereby vacuum-packaging the mold 10 with the resin film packaging material 20.

[0021] The resin film packaging material 20 is not particularly limited as long as it can vacuum-pack the mold 10, but it preferably has thermoplasticity, mold release property, shape followability, and chemical resistance. By using the resin film packaging material 20 having such characteristics, a molded article with good dimensional accuracy can be stably obtained.

[0022] The resin film packaging material 20 having thermoplasticity means that the resin film packaging material 20 is formed from a thermoplastic resin. Since the resin film packaging material 20 has thermoplasticity, the mold 10 can be surely packaged by vacuum packaging. The melting point of the thermoplastic resin is not particularly limited, but is preferably 300°C or lower.

[0023] The resin film packaging material 20 having mold release property means that the resin film packaging material 20 is difficult to adhere to the molded article. Since the resin film packaging material 20 has mold release property, the molded article can be easily separated from the mold 10 vacuum-packaged with the resin film packaging material 20 during the mold release process described below.

[0024] That the resin film packaging material 20 has shape followability means that it can be closely adhered so as to follow the shape of the mold 10 during vacuum packaging. In order for the resin film packaging material 20 to have shape followability, it is preferable that the elongation rate of the resin film packaging material 20 at 23 ± 2°C is 50% or more. Here, the elongation rate of the resin film packaging material 20 means the ratio of the maximum deformation amount (for example, the length after deformation) of the resin film packaging material 20 immediately before it breaks to the initial dimension (for example, the length) of the resin film packaging material 20. Since the resin film packaging material 20 has shape followability, a molded body with good dimensional accuracy can be stably obtained.

[0025] That the resin film packaging material 20 has chemical resistance means that it has resistance to the chemicals used in the production of the molded body (for example, the chemicals used in the slurry 30) and no dissolution or the like occurs. Since the resin film packaging material 20 has chemical resistance, it is possible to suppress the mixing of foreign substances into the molded body.

[0026] Examples of the resin used for the resin film packaging material 20 include thermoplastic resins such as polyethylene resin, polypropylene resin, polystyrene resin, acrylonitrile styrene resin, ABS resin, vinyl chloride resin, polymethyl methacrylate resin, and polyethylene terephthalate resin. These resins can be used alone or in combination of two or more. Also, the resin film packaging material 20 may have a single-layer structure or a multi-layer structure of two or more layers. As long as it is a resin film packaging material 20 composed of such a resin, the above characteristics can be obtained.

[0027] The thickness of the resin film packaging material 20 is not particularly limited as long as the above characteristics can be obtained, but it is 0.01 to 1.0 mm, more preferably 0.02 to 0.5 mm. If the thickness of the resin film packaging material 20 is less than 0.01 mm, the resin film packaging material 20 may be torn during vacuum packaging. Further, if the thickness of the resin film packaging material 20 exceeds 1.0 mm, the shape followability of the resin film packaging material 20 with respect to the mold 10 may not be sufficient.

[0028] The mold 10 has a recess 11. Since the recess 11 of the mold 10 is an area where the slurry 30 is injected, it has a shape corresponding to the outer shape (side surface and one surface) of the molded body. Therefore, the recess 11 of the mold 10 may be appropriately determined according to the shape of the molded body to be produced and is not particularly limited.

[0029] A conventional mold 100 configured by combining a plurality of molds 100 (lower mold 110 and upper mold 120) as shown in FIG. 8 is difficult to determine which of the lower mold 110 or the upper mold 120 the molded body is likely to adhere to, so it is difficult to control the application amount of the mold release agent 130, and it is also necessary to prepare a mold 100 according to the thickness of the molded body. On the other hand, the mold 10 used in the embodiment of the present invention is a single mold 10, and the thickness can be easily controlled by the amount (for example, mass) of the slurry 30. Further, since the mold release property of the molded body is ensured by the resin film packaging material 20, it is not necessary to control the application amount of the mold release agent 130.

[0030] The material constituting the mold 10 is not particularly limited, but metals (such as aluminum, aluminum alloy, SUS steel, nickel alloy, etc.), ceramics, etc. can be used. The vacuum packaging of the mold 10 with the resin film packaging material 20 can be performed using a commercially available vacuum packaging machine. The conditions for vacuum packaging are not particularly limited as long as the resin film packaging material 20 can sufficiently follow the shape of the mold 10, and may be appropriately set according to the vacuum packaging machine to be used.

[0031] <Casting and curing process> A schematic cross-sectional view for explaining the casting and curing process is shown in FIG. 2. As shown in FIG. 2, the casting and solidification process is a process of injecting the slurry 30 into the recess 11 of the mold 10 that is vacuum-packaged and solidifying it. The slurry 30 contains ceramic powder and / or metal powder. Further, the slurry 30 can further contain a reactant, a gelling agent, and a dispersion medium as needed.

[0032] The ceramic powder is not particularly limited, and examples thereof include alumina powder, zirconia powder, aluminum nitride powder, silicon carbide powder, etc. These ceramic powders may be used alone or in combination of two or more. Also, the metal powder is not particularly limited, and examples thereof include platinum powder, tungsten powder, molybdenum powder, etc. These metal powders may be used alone or in combination of two or more. The content of the ceramic powder and / or metal powder in the slurry 30 is not particularly limited, but can be, for example, 40 to 80% by mass.

[0033] The reactant contains a reactive functional group that reacts with the gelling agent to cause a curing reaction (gelation reaction). Examples of the reactant include water, polyhydric alcohols (diols such as ethylene glycol, triols such as glycerin, etc.), polybasic acids (dicarboxylic acids, etc.). The content of the reactant in the slurry 30 is not particularly limited, but can be, for example, 0.05 to 5% by mass.

[0034] The gelling agent is an additive that reacts with the reactive functional group contained in the reactant to cause a curing reaction. Examples of the gelling agent include MDI (4,4'-diphenylmethane diisocyanate), HDI (hexamethylene diisocyanate), TDI (toluene diisocyanate), etc. The gelling agent preferably has at least one of an isocyanate group (-N=C=O) and an isothiocyanate group (-N=C=S). Thereby, the reaction between the gelling agent and the reactant can be promoted. The content of the gelling agent in the slurry 30 is not particularly limited, but can be, for example, 1 to 10% by mass.

[0035] The dispersion medium is an additive for dispersing a predetermined powder. Examples of the dispersion medium include esters having two or more ester groups such as polybasic acid esters (such as dimethyl glutarate), acid esters of polyhydric alcohols (such as triacetin), and aliphatic polyhydric esters. The content of the dispersion medium in the slurry 30 is not particularly limited, but can be, for example, 10 to 40% by mass.

[0036] Also, the slurry 30 may further contain additives known in the art (such as dispersion aids, catalysts, etc.) as necessary. The dispersion aid is an additive for reducing the viscosity of the slurry 30. Examples of the dispersion aid include sorbitan fatty acid esters, polycarboxylic acid-based copolymers, and phosphate ester salt compounds of polymers. The content of the dispersion aid in the slurry 30 is not particularly limited, but can be, for example, 0.5 to 5% by mass.

[0037] The catalyst is an additive for further promoting the reaction between the gelling agent and the reactant. Examples of the catalyst include triethylenediamine, hexanediamine, 6-dimethylamino-1-hexanol, DBN (diazabicyclononene), etc. The content of the catalyst in the slurry 30 is not particularly limited, but can be, for example, 0.01 to 3% by mass.

[0038] The slurry 30 can be prepared by mixing the above components. Since the solidification (curing) of the slurry 30 starts from the time when the components are mixed, it is preferable to inject the slurry 30 into the recess 11 of the vacuum-packed mold 10 as quickly as possible after the preparation of the slurry 30.

[0039] The solidification conditions of the slurry 30 injected into the recess 11 of the vacuum-packed mold 10 are not particularly limited and can be appropriately adjusted according to the components of the slurry 30 used. For example, the slurry 30 can be solidified by standing at room temperature (25°C) for 2 to 6 hours.

[0040] In the casting and curing process, after injecting the slurry 30 into the recess 11 of the mold 10 wrapped in vacuum packaging, as shown in FIG. 3, a lid material 40 may be disposed above the recess 11 of the mold 10 wrapped in vacuum packaging. By disposing the lid material 40, excessive drying of the surface of the molded body (the surface not in contact with the recess 11) cured in the recess 11 of the mold 10 wrapped in vacuum packaging can be suppressed, and the occurrence of a difference in characteristics between the front and back of the molded body can be suppressed. In addition, the occurrence of warping in the molded body can also be suppressed.

[0041] The lid material 40 is not particularly limited, and those formed from materials such as metals and ceramics can be used. Further, the lid material 40 may be disposed so as to be in direct contact with the mold 10, or may be disposed so as to be indirectly in contact via a spacer (for example, an O-ring). In particular, as shown in FIG. 4, when injecting the slurry 30 up to the upper end of the recess 11 of the mold 10, from the viewpoint of avoiding contact between the lid material 40 and the slurry 30, it is preferable to dispose it so as to be indirectly in contact via a spacer 50 or the like.

[0042] In the casting and curing process, it is preferable to keep the recess 11 of the mold 10 wrapped in vacuum packaging horizontal. By keeping the recess 11 of the mold 10 wrapped in vacuum packaging horizontal, a molded body with a uniform thickness can be obtained. The method for keeping the recess 11 of the mold 10 horizontal is not particularly limited. For example, as shown in FIG. 5, the mold 10 wrapped in vacuum packaging may be disposed on a horizontal table 60.

[0043] <Demolding process> A schematic cross-sectional view for explaining the demolding process is shown in FIG. 6. As shown in FIG. 6, the demolding process is a process of demolding the molded body 70 (cured slurry 30) from the mold 10 wrapped in vacuum packaging. For example, by inverting the top and bottom of the mold 10, the molded body 70 can be demolded from the mold 10 by its weight. Since the resin film packaging material 20 is interposed between the molded body 70 and the mold 10, due to the releasability of the resin film packaging material 20, the molded body 70 can be easily demolded from the mold 10.

[0044] In the mold release process, the mold 10 may be recompressed within the resin film packaging material 20 that has been vacuum-packed, and the molded body 70 may be released from the mold. By recompressing within the resin film packaging material 20 in this way, the mold release property of the molded body 70 is further improved. The method of recompressing within the resin film packaging material 20 is not particularly limited. For example, the resin film packaging material 20 may simply be torn to release the vacuum, or air may be introduced into the resin film packaging material 20 by an air introduction means after the resin film packaging material 20 is torn.

Example

[0045] Hereinafter, the present invention will be described more specifically by way of examples, but the present invention is not limited in any way by these examples.

[0046] <Manufacture of Molded Body> A molded body was manufactured by sequentially performing a mold packaging process, a casting and curing process, and a mold release process. In this manufacture, seven molded bodies were produced under the same conditions. In the mold packaging process, a mold having a concave portion (300 mm in length × 300 mm in width × 5 mm in depth) was placed in a resin film packaging material (manufactured by AS ONE Corporation, made of high-density polyethylene (PE), 0.1 mm in thickness × 550 mm in width × 900 mm in length), and vacuum-packed so that the mold and the resin film packaging material were in close contact.

[0047] In the casting and curing process, after placing the mold vacuum-packed with the resin film packaging material on a horizontal table, slurry was injected into the concave portion of the vacuum-packed mold. The slurry was obtained by mixing 71% by mass of alumina powder, 1% by mass of a dispersion aid, 25% by mass of a dispersion medium, 0.1% by mass of a catalyst, 0.2% by mass of ion-exchanged water, 0.2% by mass of a reactant, and 2.5% by mass of a gelling agent. Then, a lid material was placed via an O-ring above the concave portion into which the slurry was injected and cured for 4 hours. In the mold release process, the lid material was removed, the mold was inverted up and down, and the molded body was released by recompressing within the resin film packaging material.

[0048] <Evaluation> (1) Release property In the production of seven molded articles, the release property of the molded articles was evaluated. As a result, it was confirmed that all seven molded articles had good release properties. For comparison, an attempt was made to produce a molded article by a conventional method in which a mold release agent was applied to the same mold as above, and a slurry was cast and molded. In this production, seven molded articles were also produced under the same conditions. Also, the type of slurry and the curing conditions were the same as above. As a result, among the seven molded articles, six had good release properties, but the release property of one molded article was not sufficient.

[0049] (2) Quality evaluation of molded article 1 (DSC) For the molded article obtained above, DSC (differential scanning calorimetry) was performed on the front and back surfaces at 0 to 100 μm for the dried molded article that had only been dried as a post-treatment. DSC was carried out using a differential scanning calorimeter under the conditions of atmosphere: air, heating rate: 10 °C / min. Also, for comparison, a molded article was produced in the same manner as the above production method except that a lid material was not placed above the recess into which the slurry was injected, and DSC was performed in the same manner as above. The results of DSC are shown in Fig. 7. As shown in Fig. 7, when the lid material was not placed, the difference in the DSC curves between the front and back surfaces became large. This is presumably because drying progressed on the released surface and resin segregation etc. occurred. On the other hand, when the lid material was placed, it was confirmed that the difference in the DSC curves between the front and back surfaces became small and there was almost no difference in quality between the front and back surfaces.

[0050] (3) Quality evaluation of molded article 2 (flatness and thickness difference) When the shape (flatness and thickness difference) of the molded article obtained above was three-dimensionally measured, it was confirmed that a shape equivalent to that of the conventional method was obtained.

[0051] As can be seen from the above results, according to the present invention, it was possible to provide a method capable of manufacturing a molded article with good dimensional accuracy without applying a release agent and cleaning the mold. In particular, the difference in the effects between the method of the present invention and the conventional method (Fig. 8) of applying a release agent and cleaning the mold is as shown in Table 1.

[0052]

Table 1

[0053] As shown in Table 1, in the conventional method, the yield when releasing the molded article was 70%, whereas in the method of the present invention, the yield could be improved to 100%. Further, in the method of the present invention, the equipment area required for applying the release agent and cleaning the mold was unnecessary, and the equipment area required for vacuum packaging could also be significantly reduced to one-tenth of the equipment area required for applying the conventional release agent and cleaning the mold. Further, in the method of the present invention, it was unnecessary to apply a release agent and clean the mold, and the working time required for vacuum packaging was one-thirtieth of the working time required for applying the conventional release agent and cleaning the mold, so the productivity of the molded article was significantly improved. Furthermore, in the conventional method, the use of a release agent and a cleaning liquid and two precision molds (a lower mold and an upper mold) were required as the mold, whereas in the method of the present invention, a release agent and a cleaning liquid were unnecessary, and a molded article of the same quality as the conventional one could be produced with one mold.

Explanation of Signs

[0054] 10 Mold 11 Concave portion 20 Resin film packaging material 30 Slurry 40 Cover material 50 Spacer 60 Horizontal table 70 Molded article 100 Mold 110 Lower mold 120 Upper mold 130 Release agent 140 Slurry 150 Molded article

Claims

1. A mold packaging step of vacuum packaging a mold having a recess with a resin film packaging material, A casting and curing step of injecting and curing a slurry containing ceramic powder and / or metal powder into the recess of the vacuum-packaged mold, comprising: A method for manufacturing a molded body, wherein the resin film packaging material has thermoplasticity, mold release property, shape followability, and chemical resistance.

2. The method for manufacturing a molded body according to claim 1, further comprising a mold release step of repressurizing the inside of the resin film packaging material in which the mold is vacuum-packaged after the casting and curing step to release the molded body from the mold.

3. The method for manufacturing a molded body according to claim 1 or 2, wherein in the casting and curing step, after injecting the slurry, a lid material is disposed above the recess of the mold.

4. The method for manufacturing a molded body according to claim 1 or 2, wherein the resin constituting the resin film packaging material is at least one selected from the group consisting of polyethylene resin, polypropylene resin, polystyrene resin, acrylonitrile styrene resin, ABS resin, vinyl chloride resin, polymethyl methacrylate resin, and polyethylene terephthalate resin.

5. The method for manufacturing a molded body according to claim 1 or 2, wherein in the casting and curing step, the recess of the mold is maintained horizontally.

6. The method for manufacturing a molded body according to claim 1 or 2, wherein the slurry further contains a reactant, a gelling agent, and a dispersion medium.

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