Molding die for ceramic molding and manufacturing method thereof

Abstract

To provide a molding die for ceramic molding that offers superior water absorption, is free of elution components like those in existing gypsum molds or composite dies using hydrophilic resin, enables the molding of fine ceramics and prevents an increase in manufacturing costs, as well as a manufacturing method thereof.SOLUTION: A molding die for ceramic molding is made from inorganic powders and a resin component that is composed of thermoset resin, or mixed resin of thermoset resin and thermoplastic resin, where a value of coefficient of water absorption C of the molding die, the value being expressed by the following formula (1), is 30.0% or more: C=[(B-A) / A]×100 (1), when mass A of the molding die is measured and mass B of the absorbed molding die is measured when 10 minutes elapsed after the molding die is immersed in water up to a height of 1 / 3 of volume thereof.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a ceramic molding die used in producing a sintered ceramic body, and a method for producing the same. [Background technology]

[0002] In the method of producing a sintered ceramic body, a mold is often used to mold a ceramic material into a predetermined shape. There are various methods for forming a ceramic body before sintering using a mold, such as a slip casting method, a sheet molding method, and a press molding method.

[0003] For example, in the slip casting method, a slurry (hereafter referred to as "ceramic slurry") in which ceramic raw material powder and a binder are dispersed in a dispersion medium is poured into a water-absorbent porous mold (hereafter referred to as "molding mold") having a predetermined shape. Next, most of the dispersion medium (water) contained in the ceramic slurry is absorbed into the molding mold, and the dispersion medium is separated from the ceramic raw material powder and binder. After the dispersion medium has been sufficiently separated, the ceramic molded body consisting of the ceramic raw material powder and binder is released from the molding mold.

[0004] A gypsum mold (hereafter referred to as a "gypsum mold") is used in the slip casting method, which is a common ceramic molding method. However, in the slip casting method using a gypsum mold, calcium ions and sulfate ions, which are components of gypsum (mainly calcium sulfate dihydrate), dissolve into the molded body as impurities, so it cannot be applied to molding fine ceramics, which require high purity.

[0005] Therefore, by using a ceramic porous mold that does not leach components, it is possible to produce a high-purity casting molded body. However, a ceramic casting mold has a problem in that the mold needs to be sintered at a high temperature at the sintering temperature of the ceramic when it is made, which increases the manufacturing cost of the mold.

[0006] On the other hand, ceramic-resin composite molds, in which ceramic powder is bound with resin, are sometimes used. This type of mold uses resin to mold ceramic powder, eliminating eluted components and reducing production costs. However, since its water absorption is significantly inferior to that of a plaster mold, in order to ensure the same water absorption as a plaster mold, there are problems such as the high cost of having to make the mold itself larger, as well as the difficulty of handling due to the increased weight of the mold.

[0007] The decrease in water absorption of the ceramic-resin composite type is due to the fact that the resin used in the composite is a hydrophobic resin. Therefore, it is believed that the water absorption can be improved by replacing the resin used in the composite with a hydrophilic resin. However, in molding methods that mainly use aqueous slurries, such as slip casting, if the resin is highly hydrophilic, some of the resin components may dissolve in the water, causing the purity of the molded body to decrease. In addition, the hydrophilic resin may absorb water and swell, causing the dimensional accuracy of the molded body to decrease. Thus, in slip casting to produce high-purity molded bodies, it is believed that using a hydrophobic resin is effective from the viewpoint of the purity and dimensional accuracy of the molded body.

[0008] Therefore, a ceramic molding resin mold with improved water absorption has been proposed in the following Patent Document 1. In the ceramic molding resin mold of the following Patent Document 1, water absorption is improved by 2.25 times by replacing at least a part of the inorganic powder constituting a conventional resin mold with a porous water-absorbent powder. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] JP 2003-205508 A Summary of the Invention [Problem to be solved by the invention]

[0010] In the above Patent Document 1, the water absorption is improved by 2.25 times compared to the conventional resin type. This improvement in water absorption is due to the porous water-absorbent powder in the combination of the resin component and the inorganic powder, and the resin component is still a normal hydrophobic resin. The resin component used in this composite is also desired to have water absorption, but it must be a resin component that does not have eluted components like hydrophilic resins.

[0011] Therefore, the present invention addresses the above-mentioned problems and aims to provide a ceramic molding mold that has excellent water absorption, is free of eluted components as compared with conventional plaster molds or composite molds using hydrophilic resins, is capable of molding fine ceramics, and does not increase manufacturing costs, as well as a manufacturing method thereof. [Means for solving the problem]

[0012] In order to solve the above problems, the inventors conducted extensive research and found that when a molding die is made by compounding a hydrophobic thermosetting resin with a ceramic raw material, the hydrophobicity of the resin is weakened and the resin becomes hydrophilic without producing eluted components by performing heat treatment at a temperature somewhat lower than the temperature at which the resin thermally decomposes, thereby achieving the above object, and thus completing the present invention.

[0013] That is, according to claim 1, the ceramic molding die of the present invention has the following features: A ceramic molding die made of an inorganic powder and a resin component, the resin component is made of a thermosetting resin or a mixed resin of a thermosetting resin and a thermoplastic resin, and the resin component is made of a part or a whole of a carbonized component; The mass A of the ceramic forming mold is measured, the mold is immersed in water up to a height of 1 / 3 of its volume, and then the mass B of the mold that has absorbed water after 10 minutes is measured. The mass A of the ceramic forming mold is measured according to the following formula (1): C=[(BA) / A]×100····(1) The mold is characterized in that its water absorption rate C, as shown by C=30.0% or more.

[0014] According to claim 2, the present invention provides a ceramic molding die according to claim 1, The inorganic powder is characterized in that it is composed of at least one material selected from the group consisting of ceramics, metals, and carbon.

[0015] According to claim 3, the present invention provides a ceramic molding die according to claim 1 or 2, The water absorption rate C is characterized by being 52.0% or more.

[0016] According to claim 4, the method for producing a ceramic molding die of the present invention comprises the steps of: The method includes a step of mixing an inorganic powder and a resin component to prepare a mixed material, a step of molding the mixed material in a press molding die to prepare a press molded body, and a step of heat treating the press molded body and preparing a mold, The resin component is composed of a thermosetting resin or a mixed resin of a thermosetting resin and a thermoplastic resin, The heat treatment is performed at a temperature equal to or higher than the curing temperature and equal to or lower than the thermal decomposition temperature of the thermosetting resin, The mass A of the mold thus produced was measured, and the mold was then immersed in water up to a height of 1 / 3 of its volume. After 10 minutes, the mass B of the mold that had absorbed water was measured. The mass A of the mold thus produced was then measured, and the mass B of the mold that had absorbed water after 10 minutes was then calculated based on the following formula (1): C=[(BA) / A]×100····(1) The mold is characterized in that its water absorption rate C, as shown by C=30.0% or more.

[0017] According to claim 5, the method for producing a ceramic molding die of the present invention comprises the steps of: The method includes a step of mixing an inorganic powder and a resin component to prepare a mixed material, a step of molding the mixed material in a press molding die to prepare a press molded body, and a step of heat treating the press molded body and preparing a mold, The resin component is composed of a thermosetting resin or a mixed resin of a thermosetting resin and a thermoplastic resin, The heat treatment is performed at a temperature at which the resin component is partially or entirely carbonized, The mass A of the mold thus produced was measured, and the mold was then immersed in water up to a height of 1 / 3 of its volume. After 10 minutes, the mass B of the mold that had absorbed water was measured. The mass A of the mold thus produced was then measured, and the mass B of the mold that had absorbed water after 10 minutes was then calculated based on the following formula (1): C=[(BA) / A]×100····(1) The mold is characterized in that its water absorption rate C, as shown by C=30.0% or more.

[0018] According to claim 6, the present invention provides a method for producing a ceramic molding die according to claim 4 or 5, The ratio of the resin component in the mixed material is within a range of 4 volume % to 40 volume % relative to the volume of the inorganic powder.

[0019] According to claim 7, the present invention provides a method for producing a ceramic molding die according to claim 4 or 5, The water absorption rate C is characterized by being 52.0% or more.

[0020] According to claim 8, the present invention provides a method for producing a ceramic molding die according to claim 7, The ratio of the resin component in the mixed material is within a range of 4 volume % to 40 volume % relative to the volume of the inorganic powder. Effect of the Invention

[0021] According to the above configuration, the ceramic molding die according to the present invention is a ceramic molding die made of an inorganic powder and a resin component, the resin component being made of a thermosetting resin or a mixed resin of a thermosetting resin and a thermoplastic resin, and the resin component being made of a part or all of a carbonized component, and a mass A of the ceramic molding die is measured, the mold is immersed in water up to a height of 1 / 3 of its volume, and then a mass B of the mold that has absorbed water after 10 minutes has elapsed is measured, and the mass A of the mold is calculated based on the mass A of the mold that has absorbed water after 10 minutes has elapsed, and the mass B of the mold that has absorbed water after 10 minutes has elapsed satisfies the following formula (1): C=[(BA) / A]×100····(1) The mold is characterized in that its water absorption rate C, as shown by C=30.0% or more.

[0022] This makes it possible to provide a ceramic molding mold that has excellent water absorption, is free of eluted components like those in conventional plaster molds or composite molds using hydrophilic resins, is capable of molding fine ceramics, and does not require high manufacturing costs.

[0023] According to the above configuration, the inorganic powder is preferably composed of at least one selected from ceramics, metal, and carbon. The water absorption rate C is more preferably 52.0% or more. This makes it possible to more specifically and effectively exert the above-mentioned effects.

[0024] According to the above configuration, the method for manufacturing a ceramic molding die of the present invention includes a step of mixing an inorganic powder with a resin component to prepare a mixed material, a step of molding the mixed material in a press molding die to prepare a press molded body, and a step of heat-treating the press molded body and preparing a molding die. Here, the resin component is composed of a thermosetting resin or a mixed resin of a thermosetting resin and a thermoplastic resin, and the heat treatment is performed at a temperature equal to or higher than the curing temperature and equal to or lower than the thermal decomposition temperature of the thermosetting resin. As a result, the value of the water absorption rate C of the molding die shown in the above formula (1) becomes 30.0% or more.

[0025] The heat treatment may be performed at a temperature at which the resin component is partially or entirely carbonized. The ratio of the resin component in the mixed material is preferably within a range of 4% by volume to 40% by volume relative to the volume of the inorganic powder. The water absorption coefficient C is more preferably 52.0% or more.

[0026] As a result, it is possible to provide a method for manufacturing a ceramic molding mold that has excellent water absorption properties, is free of eluted components like those of conventional plaster molds or composite molds using hydrophilic resins, is capable of molding fine ceramics, and does not increase manufacturing costs. [Brief description of the drawings]

[0027] [Figure 1] 1 is a graph showing the results of thermogravimetric analysis (TG-DSC curve) of the phenolic resin used in Example 1. [Diagram 2] 2 is a photograph of the surface of the molded body obtained in Example 1, observed with an electron microscope. [Diagram 3] 3 is a photograph of the surface of the molded body obtained in Example 1 after the second heat treatment, observed with an optical microscope. [Figure 4] 2 is a photograph of the surface of the molded body obtained in Example 1 after the first heat treatment, observed with an optical microscope. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] The ceramic forming mold according to the present invention will be specifically described below with reference to a manufacturing method thereof. The ceramic forming mold according to the present invention can be formed by a slip casting method, a sheet forming method, a press forming method or the like.

[0029] First, the components of the ceramic molding die according to the present invention will be described. In the present invention, the ceramic molding die is composed of an inorganic powder and a resin component. Here, the inorganic powder is not particularly limited as long as it is used in conventional ceramic-resin composite dies. Among these, it is preferable to use ceramics such as metal oxides, metal nitrides, and metal carbides, metals, carbon, etc. alone or in combination. In addition to powders, particles such as plate-shaped particles, rod-shaped particles, spherical particles, porous particles, and fibrous particles may be used.

[0030] On the other hand, the resin component is not particularly limited, and for example, it is preferable to use a thermosetting resin alone or a mixed resin of a thermosetting resin and a thermoplastic resin. Examples of the thermosetting resin include phenol resin, epoxy resin, unsaturated polyester resin, alkyd resin, urea resin, melamine resin, urethane resin, and silcone resin. Among these, it is preferable to use a phenol resin or an epoxy resin in the present invention.

[0031] When using a phenolic resin as a thermosetting resin, it may be cured in the form of a novolac resin or a resol resin, or a fine particle phenolic resin such as a heat melt curing type may be used. On the other hand, when using an epoxy resin, it is preferable to use a two-liquid type resin in which a prepolymer before crosslinking network formation and a curing agent are mixed and subjected to a heat curing treatment. In addition, the combination of the two components constituting the epoxy resin is not particularly limited, and is not limited to the typical combination of bisphenol A and epichlorohydrin.

[0032] The thermoplastic resin to be mixed with the thermosetting resin is not particularly limited, and examples thereof include polyethylene, polypropylene, polystyrene, polyvinyl acetate, polyacrylate, polyacrylamide, polyether, polyvinyl chloride, polyvinylidene chloride, polyacrylonitrile, polyfluoroethylene, polyester, polycarbonate, polyamide, polyimide, polysulfone, and polyvinyl butyral. Among these, it is preferable to use polyamide or polyvinyl butyral in the present invention. When using a mixed resin of a thermosetting resin and a thermoplastic resin, it is preferable that the ratio of the thermosetting resin is 1% by volume or more.

[0033] Next, we will explain the manufacturing method for ceramic molding dies. First, inorganic powder and resin components are mixed to form a mixed material, which is then molded into a desired shape. In the case of slip casting, the mixed material is mixed with water and cast into a mold, and then dried in an electric oven to form the shape. On the other hand, in the case of press molding, the mixed material is heated and pressurized in a press molding die to form the shape.

[0034] Here, the ratio of the resin component in the mixed material is preferably within the range of 4% to 40% by volume relative to the volume of the inorganic powder. If the ratio of the resin component is less than 4% by volume, the water absorption rate of the ceramic molding mold produced will be significantly lower than that of a conventional plaster mold. On the other hand, if the ratio of the resin component is more than 40% by volume, the strength of the ceramic molding mold produced will be reduced, which may cause problems in use.

[0035] Next, the molded and dried mixed material is heat-treated at the curing temperature of the thermosetting resin (this is called the "first heat treatment") to heat-cure the thermosetting resin. The heating temperature in this first heat treatment may be appropriately selected depending on the type of thermosetting resin used. The operations up to this point are similar to conventional manufacturing methods of ceramic resin composites. The present invention is characterized in that the heat-cured mixed material is further heat-treated at a high temperature (this is called the "second heat treatment").

[0036] The heating temperature of this second heating treatment is equal to or higher than the curing temperature and equal to or lower than the thermal decomposition temperature of the thermosetting resin. This heating treatment is not only applicable when the resin component is a single thermosetting resin, but also when the resin component is a mixed resin of a thermosetting resin and a thermoplastic resin. In the present invention, the first heating treatment is performed during the temperature increase stage of the second heating treatment, and the first heating treatment and the second heating treatment may be performed as a continuous series of heating treatment operations.

[0037] The present inventors have found that the ceramic molding die molded from a thermosetting resin, which is originally hydrophobic, becomes hydrophilic by setting the heating temperature of the second heat treatment to be equal to or higher than the curing temperature and equal to or lower than the thermal decomposition temperature. The reason why the ceramic molding die becomes hydrophilic by the second heat treatment is not clear, but the present inventors consider it as follows.

[0038] In general, in a thermosetting resin, a plurality of monomers are continuously bonded to each other through a condensation reaction or an addition reaction. However, the terminals of the resin have low thermal stability because there is no bond partner. In addition, many of these terminals are present on the surface of the resin. Therefore, the surface of the resin is more likely to undergo thermal decomposition at a relatively low temperature compared to the inside. As a result, the surface of the resin becomes hydrophilic by decomposition or carbonization at a temperature lower than the thermal decomposition temperature of the resin (below the thermal decomposition temperature). However, this does not result in the generation of eluted components. The present inventors observed the molded body before and after the second heat treatment with an optical microscope and confirmed that the surface of the resin component was carbonized by the second heat treatment (details will be described later). EXAMPLES

[0039] Next, the present invention will be specifically described based on each example. Each of the following examples is a method for manufacturing a ceramic molding die used in manufacturing a ceramic sintered body. In order to facilitate evaluation of the water absorption of the molds in the examples and comparative examples, a rectangular column molded body (test piece) with a cross section of 20 mm x 20 mm and a height of 30 mm was produced. In each example, alumina powder and silica powder are used as inorganic powders, and phenolic resin and epoxy resin are used as resin components. However, the inorganic powder and resin component in the present invention are not limited to these. In addition, the present invention is not limited to only the following examples.

[0040] Example 1 In this Example 1, a mixed material was prepared using a porous alumina powder as an inorganic powder and a phenolic resin, which is a thermosetting resin, as a resin component. In addition, a molded body (test piece) for evaluating water absorption was produced by a press molding method in the same manner as in the manufacturing of a ceramic molding die.

[0041] First, alumina powder (Sumitomo Chemical Co., Ltd.; A21, particle size 51 μm) and functional fine particle phenolic resin (Air Water Bellpearl Co., Ltd.; Bellpearl S, product number S890) were mixed in a 1 L plastic container to prepare a mixed material. The amount of phenolic resin used was 29 vol% relative to the volume of the alumina powder. Next, the mixed material was put into a press molding die of a predetermined shape, and a press molded body was produced by press molding at 90 ° C, 50 kN, and 1 hour. Next, the press molded body was heat treated (first and second heat treatments) in an oven at 230 ° C to produce a hydrophilic molded body. Table 1 shows the resin ratio at the time of mixing, molding method, first and second heat treatment temperatures, resin ratio after heating, and water absorption rate of the molded body produced in this Example 1.

[0042] In this Example 1, the heat treatment temperature was set to 230°C because the thermosetting temperature of the functional particulate phenolic resin used was 150°C and the weight loss starting temperature was 350°C. Specifically, this was determined from the thermogravimetric analysis of the functional particulate phenolic resin used. FIG. 1 is a graph showing the results of the thermogravimetric analysis (TG-DSC curve) of the phenolic resin used in this Example 1. In FIG. 1, an exothermic peak accompanied by a small weight loss is observed at 230°C in the TG-DSC curve of the phenolic resin. This indicates that the resin surface is thermally decomposed, which causes the surface to lose its hydrophobicity and become hydrophilic. After that, a rapid weight loss associated with the thermal decomposition of the resin is observed after 350°C.

[0043] The resin content of the molded body after preparation is reduced by several percent in weight due to heat treatment. Therefore, another molded body prepared in the same manner was subjected to high-temperature treatment at 1000°C in air to remove the resin content. The resin content of the molded body after heat treatment was measured from the weight loss due to this high-temperature treatment.

[0044] Also, Fig. 2 is a photograph of the surface of the molded body obtained in this Example 1, observed with an electron microscope. Since the state of the functional particulate phenolic resin is difficult to see in the electron microscope photograph of Fig. 2, it was also observed with an optical microscope. Fig. 3 is a photograph of the surface of the molded body obtained in this Example 1 after the second heat treatment, observed with an optical microscope. Also, Fig. 4 is a photograph of the surface of the molded body obtained in this Example 1 after the first heat treatment, observed with an optical microscope. In Figs. 3 and 4, the white parts are alumina powder, and the black parts are functional particulate phenolic resin.

[0045] In this Example 1, one stage of heat treatment (first and second heat treatments) was performed. Therefore, the photograph of the molded body before the second heat treatment was observed after the heat treatment (only the first heat treatment) of Comparative Example 1 described later (same as Example 1 except for the heat treatment temperature). In addition, in the monochrome photographs of Figures 3 and 4 attached to this specification, it is difficult to see the difference in the heat treatment temperature on the surface of the functional particulate phenolic resin. However, in the color photographs of Figures 3 and 4 (stored as the originals) actually observed, it was clearly observed that the surface of the functional particulate phenolic resin in Figure 3 was carbonized.

[0046] Example 2 In this Example 2, except that the amount of the phenol resin used was 21% by volume relative to the volume of the alumina powder, a hydrophilic molded body was produced in the same manner as in Example 1. The resin ratio at the time of mixing, molding method, first and second heat treatment temperatures, resin ratio after heating, and water absorption rate of the molded body produced in this Example 2 are shown in Table 1.

[0047] Example 3 In this Example 3, except that the amount of the phenol resin used was 33 volume % relative to the volume of the alumina powder, a hydrophilic molded body was produced in the same manner as in Example 1. The resin ratio at the time of mixing, molding method, first and second heat treatment temperatures, resin ratio after heating, and water absorption rate of the molded body produced in this Example 3 are shown in Table 1.

[0048] Example 4 In this Example 4, a plate-like alumina powder (manufactured by Fujimi Incorporated, PWA3, particle size 3 μm) was used as the inorganic powder, and the amount of phenolic resin used was 11 vol% relative to the volume of the alumina powder, but a hydrophilic-treated molded body was produced in the same manner as in Example 1. The resin ratio at the time of mixing, molding method, first and second heat treatment temperatures, resin ratio after heating, and water absorption rate of the molded body produced in this Example 4 are shown in Table 1.

[0049] Example 5 In this Example 5, a mixed material was prepared using pulverized silicon carbide as an inorganic powder and epoxy resin, a thermosetting resin, as a resin component. First, silicon carbide (manufactured by Fujimi Incorporated; GC1000, particle size 12.0 μm) and epoxy resin (main agent: EPICRON855 manufactured by DIC Corporation, hardener: ST12 manufactured by Mitsubishi Chemical Corporation) were mixed in a planetary centrifugal mixer (manufactured by Shinki Co., Ltd., model: ARE-310) to prepare a mixed material. The amount of epoxy resin used was 5% by volume relative to the volume of silicon carbide.

[0050] Next, the mixed material was put into a press molding die of a predetermined shape, and a press molded body was produced by press molding at 150°C, 50kN, and 1 hour. Next, the press molded body was heat-treated (first and second heat treatments) in an oven at 230°C to produce a hydrophilic molded body. The resin ratio at the time of mixing, molding method, first and second heat treatment temperatures, resin ratio after heating, and water absorption rate of the molded body produced in this Example 5 are shown in Table 1.

[0051] Example 6 In this Example 6, the same porous alumina powder and phenolic resin as in Example 1 were used to produce a molded body for evaluating the water absorption of a ceramic molding die by a slip casting method.

[0052] First, the same alumina powder as in Example 1 and functional fine particle phenolic resin were mixed in a 1 L plastic container to prepare a mixed material. The amount of phenolic resin used was 40 volume % relative to the volume of the alumina powder. Next, 100 g of the mixed material was mixed with 100 g of water, cast into a casting mold of a given shape, and dried in an electric oven at 80°C for 1 hour to produce a casting molded body.

[0053] Next, the molded body was heat-treated in an oven at 150°C (first heat treatment) to heat-set the molded body. The heat-set molded body was then heat-treated in an oven at 230°C (second heat treatment) to produce a molded body that had been hydrophilized. Table 1 shows the resin ratio at the time of mixing, molding method, first and second heat treatment temperatures, resin ratio after heating, and water absorption rate of the molded body produced in this Example 6.

[0054] Example 7 In this Example 7, the same porous alumina powder as in Example 1 was used as the inorganic powder, and a mixed resin of a phenolic resin, which is a thermosetting resin, and a nylon resin, which is a thermoplastic resin, was used as the resin component to prepare a mixed material. In addition, a molded body (test piece) for evaluating water absorption was produced by the press molding method in the same manner as in the method for producing a ceramic molding die.

[0055] First, the same alumina powder as in Example 1, functional fine particle phenolic resin, and nylon resin (VESTOSINT2070 manufactured by Daicel-Evonik Co., Ltd.) were mixed in a 1 L plastic container to prepare a mixed material. The amount of phenolic resin used was 29 vol% relative to the volume of the alumina powder, and the amount of nylon resin used was 1 vol% relative to the volume of the alumina powder. Other conditions were the same as in Example 1, and a hydrophilic molded body was produced. The resin ratio at the time of mixing, molding method, first and second heat treatment temperatures, resin ratio after heating, and water absorption rate of the molded body produced in this Example 7 are shown in Table 1.

[0056] Example 8 In this Example 8, a molded body was produced in which the resin component was entirely carbonized. The same porous alumina powder and thermosetting phenolic resin as in Example 1 were used, and the amount of phenolic resin was set to 29% by volume relative to the volume of the alumina powder as in Example 1 to produce a press molded body. Next, the press molded body was heat-treated (first and second heat treatments) in a nitrogen atmosphere at 600°C to produce a molded body in which the resin component was entirely carbonized and hydrophilized. Table 1 shows the resin ratio at the time of mixing, molding method, first and second heat treatment temperatures, resin ratio after heating, and water absorption rate of the molded body produced in this Example 8.

[0057] Comparative Example 1 This Comparative Example 1 corresponds to the above-mentioned Example 1, and a mixed material was prepared by blending the same alumina powder and phenolic resin as in Example 1 in the same ratio, and a molded body for evaluating water absorption was produced by a press molding method of a predetermined shape. In this Comparative Example 1, a heat treatment (first heat treatment) was performed at 150°C, which is the thermosetting temperature of the phenolic resin, and the heat treatment (second heat treatment) at 230°C performed in Example 1 was not performed.

[0058] Comparative Example 2 In this Comparative Example 2, in order to compare each Example with a conventional plaster mold, a plaster molded body was produced by a casting method to evaluate water absorption. First, gypsum powder (San-Esu Gypsum Co., Ltd.) was mixed with water, poured into a casting mold of a given shape, and left for one day, and then dried in an electric oven at 40°C for one day to produce a casting molded body. In this Comparative Example 2, the water absorption was evaluated using this casting molded body.

[0059] <Evaluation method for water absorbency> Next, the water absorption of each molded body produced in the above Examples 1 to 8 and Comparative Examples 1 and 2 was evaluated. The evaluation of water absorption was performed using a molded body (test piece) in the shape of a rectangular column with a cross section of 20 mm x 20 mm and a height of 30 mm, as described above. The test piece may be produced directly from the molding method by making the molded body used in the above Examples 1 to 8 and Comparative Examples 1 to 2 the same size as the test piece. Alternatively, the test piece may be produced by cutting out a molded body larger than the test piece for the water absorption test.

[0060] The water absorption of each molded body (test piece) was evaluated as follows. First, the mass A of the rectangular column of the molded body (test piece) produced was measured. Next, the molded body (test piece) was immersed in water (at room temperature) to a height of 1 / 3 of its volume. After 10 minutes of immersion, the mass B of the molded body (test piece) that had absorbed water was measured. Using these values, the following formula (1) was calculated. C=[(BA) / A]×100····(1) The water absorption rate C of the molded body (test piece) is calculated, where C is the water absorption rate of the molded body (test piece). The condition for the ceramic molding mold according to the present invention is that this C value is 30.0% or more. This value is set as a sufficient practical performance for the water absorption of a ceramic-resin composite mold, and the molded body can be used in the same way as a conventional plaster mold. The evaluation results of the water absorption of each molded body (test piece) of Examples 1 to 8 and Comparative Examples 1 and 2 are shown in Table 1.

[0061] [Table 1]

[0062] As can be seen from Table 1, all the molded bodies (test pieces) of Examples 1 to 8 showed good values ​​of water absorption of 30.0% or more. The water absorption of 30% is twice the water absorption of 15% of Comparative Example 1, which uses porous alumina that is thought to be more hydrophilic than the conventional ceramic-resin composite type, and is a very good value. It is also close to about 60% of the water absorption of 51% of the conventional plaster mold (Comparative Example 2), and fully shows practical performance as a ceramic-resin composite type water absorption. In Examples 1, 2, 4, 7, and 8, the water absorption of each was 52% or more, which was higher than the water absorption of the conventional plaster mold (Comparative Example 2) and was a very good result.

[0063] It was also confirmed that in all of Examples 1 to 8, there was no elution of components, as in conventional plaster molds or composite molds using hydrophilic resins. For these reasons, all of the molding molds in Examples 1 to 8 can be used to mold fine ceramics. Furthermore, in these Examples, the manufacturing costs do not increase.

[0064] As described above, according to the above embodiment, it is possible to provide a ceramic forming mold and a manufacturing method thereof which have excellent water absorption properties, are free of eluted components as compared with conventional plaster molds or composite molds using hydrophilic resins, are capable of forming fine ceramics, and do not involve high manufacturing costs.

Claims

1. A ceramic molding die made of an inorganic powder and a resin component, the resin component is made of a thermosetting resin or a mixed resin of a thermosetting resin and a thermoplastic resin, and the resin component is made of a part or a whole of a carbonized component; The mass A of the ceramic molding mold is measured, the mold is immersed in water up to a height of 1 / 3 of its volume, and then the mass B of the mold that has absorbed water after 10 minutes is measured. The mass A of the ceramic molding mold is measured according to the following formula (1): C=[(B-A) / A]×100...(1) The mold for molding ceramics, characterized in that the water absorption rate C of the mold, as shown by the formula (1) is 30.0% or more.

2. 2. The ceramic molding die according to claim 1, wherein the inorganic powder is made of at least one material selected from the group consisting of ceramics, metals, and carbon.

3. 3. The ceramic molding die according to claim 1, wherein the water absorption C is 52.0% or more.

4. The method includes a step of mixing an inorganic powder and a resin component to prepare a mixed material, a step of molding the mixed material in a press molding die to prepare a press molded body, and a step of heat treating the press molded body and preparing a mold, The resin component is composed of a thermosetting resin or a mixed resin of a thermosetting resin and a thermoplastic resin, The heat treatment is performed at a temperature equal to or higher than the curing temperature and equal to or lower than the thermal decomposition temperature of the thermosetting resin, In the produced mold, the mass A of the mold is measured, the mold is immersed in water to a height of ⅓ of its volume, and then the mass B of the mold that has absorbed water after 10 minutes is measured. The mass A of the mold is then measured, and the mass B of the mold that has absorbed water after 10 minutes is measured. C=[(B-A) / A]×100...(1) 3. A method for producing a ceramic molding die, characterized in that the water absorption rate C of the molding die, as shown by the formula (1) is 30.0% or more.

5. The method includes a step of mixing an inorganic powder and a resin component to prepare a mixed material, a step of molding the mixed material in a press molding die to prepare a press molded body, and a step of heat treating the press molded body and preparing a mold, The resin component is composed of a thermosetting resin or a mixed resin of a thermosetting resin and a thermoplastic resin, The heat treatment is performed at a temperature at which the resin component is partially or entirely carbonized, In the produced mold, the mass A of the mold is measured, the mold is immersed in water to a height of 1 / 3 of its volume, and then the mass B of the mold that has absorbed water after 10 minutes is measured. The mass A of the mold is then measured, and the mass B of the mold that has absorbed water after 10 minutes is measured. C=[(B-A) / A]×100...(1) 3. A method for producing a ceramic molding die, characterized in that the water absorption rate C of the molding die, as shown by the formula (1) is 30.0% or more.

6. 6. The method for manufacturing a ceramic molding die according to claim 4, wherein the ratio of the resin component in the mixed material is within a range of 4 volume % to 40 volume % relative to the volume of the inorganic powder.

7. 6. The method for producing a ceramic molding die according to claim 4, wherein the value of the water absorption C is 52.0% or more.

8. 8. The method for manufacturing a ceramic molding die according to claim 7, wherein the ratio of the resin component in the mixed material is within a range of 4 volume % to 40 volume % relative to the volume of the inorganic powder.

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