JP2003127120A - Mold for molding ceramics and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mold for molding ceramics enhanced not only in durability but also in abrasion resistance, mechanical strength and heat resistance by suppressing fluctuations of the volume in the space of a molding surface caused by repeatedly performing molding many times. SOLUTION: Water is added to and mixed with 40-70 pts.wt. of a siliceous mineral, 10-40 pts.wt. of cement, 2-25 pts.wt. of gypsum, 1-10 pts.wt. of siliceous fine particles with a mean particle size of 0.1-<2 μm and 0.2-5 pts.wt. of a fibrous mineral in an amount of 35-60 pts.wt. to prepare a slurry. The obtained slurry is cast in the molding space of a matrix for molding a mold and cured and demolded to obtain a molded object (mold). Silica is used as the siliceous mineral and silica fume is used as the siliceous fine particles and sepiolite is used as the fibrous mineral.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramics molding die used when molding a ceramics product by casting or the like, and a method for producing the same.

[0002]

BACKGROUND OF THE INVENTION Since plaster has been used as a construction aid for structures since ancient Egypt, it has been used in various industries such as stabilizers for cement preservation, construction materials, agriculture, pigments, etc. Widely used in the fields of casting, arts and crafts, surgical medicine, dentistry, and the ceramics industry.

A gypsum mold used for molding a ceramic body is obtained by using hemihydrate gypsum as a starting material, adding an appropriate amount of water thereto, stirring and mixing the mixture, and casting the slurry into a molding die for molding. In this case, the slurry undergoes a hydration reaction and transforms into gypsum dihydrate in a short time and solidifies and solidifies. The slurry has high homogeneity and fluidity, and is characterized by being uniformly filled and solidified in the mother die by casting. The gypsum mold thus obtained is used as a general-purpose material because of its characteristics such that the mold copy is highly accurate and the molding and processing are easy.

In recent years, ceramic molding methods have been diversified,
Various functions are required for molding dies. To solve these problems, it is necessary to develop a product that improves the mechanical strength such as hardness, abrasion resistance, and bending strength by mixing raw gypsum with organic or inorganic fibers or inorganic powder. Has been done.

For example, JP-A-6-157117 and JP-A-6-155426 disclose molding gypsum molds having increased mechanical strength by mixing and dispersing carbon fiber in the gypsum structure of the base material. ing. In addition, JP-A-7-24660
No. 9 discloses a gypsum mold for molding in which the gypsum contains zeolite powder to increase the mold density and thereby improve the mechanical strength.

[0006]

However, the conventional gypsum mold has a problem that the molding surface is dissolved in water and the durability is lowered. That is, gypsum is poorly soluble in water, but exhibits solubility in water.Therefore, during molding of the ceramic body, the mold surface in contact with the molding material, that is, the molding surface absorbs water in the molding material and slightly dissolves. To do. Then, as the number of times of repeated molding with the same gypsum mold increases, the melting amount thereof gradually increases, and accordingly, the internal volume of the space of the molding surface increases, and the internal volume fluctuates. As a result, there is a problem in that an error occurs in the size and shape of the ceramic body that is a molded body, and a homogeneous product cannot be obtained. For example, when forming a bottle having a sake bottle shape, the same gypsum mold is repeatedly formed 100 times to produce 100 pieces, which causes a problem that the outer dimension of the container gradually increases as the number of forming times increases. Therefore, the number of times of molding with the same mold is naturally limited, and the mold must be discarded relatively early, resulting in poor durability.

Further, the conventional gypsum mold is not sufficient in terms of abrasion resistance. For example, when forming a dish-shaped container by the roller machine molding method, the clay is pressed on the mold surface with a conical roller-shaped spatula on a rotating plate, and therefore the mold surface is greatly stressed. Therefore, the mold surface is worn, and the degree of wear of the mold surface gradually increases as the number of molding times increases, which causes problems such as deterioration of molding accuracy and non-uniformity of the size of the molded body. As described above, the conventional plaster mold has a limit in the number of times of repeated molding with the same mold in view of insufficient wear resistance, and improvement in durability has been desired.

Further, in the past, there was a problem that the gypsum mold was damaged by an external force when the gypsum mold was handled, and technical improvement in terms of strength was never satisfactory.

The conventional gypsum mold has a thermal property of 4
The stable range is 1 ° C or lower, and the physical properties such as strength are deteriorated in the stable range in the temperature range higher than that, and the physical properties such as strength are deteriorated. Therefore, the gypsum mold in the wet state used for forming the base is dried and re-formed. In use, the drying temperature was limited to 41 ° C. or lower, which took time to dry and the molding cycle was inefficient.

The present invention is intended to solve the problems of the conventional gypsum mold, and suppresses fluctuations in the space volume of the molding surface to improve durability, wear resistance, and mechanical properties. An object of the present invention is to provide a ceramics molding die having improved mechanical strength and heat resistance, and a method for producing the same.

[0011]

SUMMARY OF THE INVENTION The present invention is a ceramics molding die characterized by being formed of a material comprising siliceous mineral, cement and gypsum.

The above materials constituting the molding die of the present invention include:
Silica fine particles and / or fibrous minerals having an average particle size of 0.1 μm or more and less than 2 μm can be blended. By mixing the siliceous fine particles and / or the fibrous mineral, it is possible to adjust the porous characteristics such as the curing rate, the porosity, the water absorption rate and the surface roughness, and the dimensional accuracy of the mold. It is possible to easily release the ceramic base material at the time of molding.

The material composition of the mold of the present invention is 40 to 70 parts by weight of siliceous mineral, 10 to 40 parts by weight of cement, and 2 to 25 parts by weight of gypsum.

When the above-mentioned siliceous fine particles and fibrous mineral are blended with these materials, the material composition of the present invention is 40 to 70 parts by weight of siliceous mineral, 10 to 40 parts by weight of cement, 2 to 25 parts by weight of gypsum, The silica fine particles are 1 to 10 parts by weight, and the fibrous mineral is 0.2 to 5 parts by weight.

In producing the mold for ceramics of the present invention, first, 40 to 70 parts by weight of siliceous mineral and 1 part of cement are used.
0 to 40 parts by weight and 2 to 25 parts by weight of gypsum are mixed with 35 to 60 parts by weight of water to form a slurry. Then, the obtained slurry is cast into the molding space of the mold for molding, cured, and released to obtain a molded body (molding die).

In the case where the mold of the present invention contains the above-mentioned siliceous fine particles and fibrous mineral, when manufacturing the mold of the present invention, first, 40 to 70 parts by weight of siliceous mineral and 10 to 40 parts by weight of cement. 2 to 25 parts by weight of gypsum, 1 to 10 parts by weight of the above-mentioned siliceous fine particles, and 0.2 to 5 parts by weight of fibrous mineral are added and mixed with 35 to 60 parts by weight of water to form a slurry.
Then, the obtained slurry is cast into the molding space of the mold for molding, cured, and released to obtain a molded body (molding die).

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION The mold for porcelain molding of the present invention comprises siliceous minerals, cement and gypsum, and further contains silicic acid fine particles and / or fibrous minerals having an average particle size of 0.1 μm or more and less than 2 μm. Is preferably blended. That is, in the present invention, siliceous minerals, cement and gypsum are basic material components, and either one or both of the above siliceous fine particles and fibrous minerals can be added to these.

As the siliceous mineral in the present invention, minerals having a small amount of clay component are preferable, and examples thereof include granites such as silica stone and feldspar, wax stones and siliceous sandstone. The main component of siliceous mineral is SiO ₂ , and the content of this main component SiO ₂ is 6
2% or more is preferable.

In the present invention, the siliceous mineral is granular and its average particle size is preferably 2 to 100 μm. When the average particle diameter exceeds 100 μm, it becomes difficult to increase the total pore specific surface area of the molding die of the present invention, and it is also difficult to improve the water absorption. On the other hand, since siliceous minerals are hard, it is extremely difficult to finely pulverize them with a general-purpose pulverizing machine, and the cost is high, so the average particle size is 2
It is not economically expedient to use one having a thickness of less than μm.

In the present invention, the more preferable average particle diameter of the siliceous mineral is 3 to 60 μm.

Examples of the cement in the present invention include Portland cement, white Portland cement, early-strength Portland cement, medium heat Portland cement, blast furnace cement, silica cement, fly ash cement, alumina cement, magnesia cement, and the like. , White Portland cement, early strength Portland cement and silica cement are preferred.

As the gypsum, the same material as that used in the conventional gypsum mold can be used.

Silica fine particles having an average particle size of 0.1 μm or more and less than 2 μm are appropriately blended in order to adjust the porous characteristics of the molding die of the present invention. Here, the porous characteristics refer to properties such as curing rate, porosity, water absorption rate and surface roughness. Examples of the siliceous fine particles include silica fume and white carbon, but silica fume is preferable. As the silica fume, a by-product obtained at the time of manufacturing a silicon-based semiconductor material or a by-product collected from an electric furnace at the time of manufacturing silicon metal or ferro-silicon can be used, and the main crystalline phase is only cristobalite and the main component is SiO 2. ₂ Content is 90% or more.

The average particle diameter of the siliceous fine particles is 0.1 μm.
Above 2 μm means that when the average particle size is less than 0.1 μm, it cannot contribute to the improvement of the water absorption rate and also causes handling problems such as dust generation in the process. On the other hand, when the average particle size is 2 μm or more, This is because it cannot contribute to the increase of the pore specific surface area and the improvement of the water absorption. The preferable average particle size of the siliceous fine particles is 0.1 to 0.3 μm.

In order to adjust the porous characteristics of the molding die of the present invention, it is preferable to add a fibrous mineral. Examples of this fibrous mineral include sepiolite and attapulgite, and sepiolite is preferable. Sepiolite MgO-SiO ₂ -H has fine particle size of _{2 O} with magnesium silicate as a main component has a structure of being integrated fiber length 0.2 to 2 .mu.m, fine as particle shape It has a good fibrous morphology and is very dispersible in water. Sepiolite and attapulgite can be miniaturized by using a crusher such as a ball mill, and in the case of sepiolite, the bundled fibers are loosened by the miniaturization to be made into small fibers.

The material composition of the molding die of the present invention is siliceous mineral 4
0-70 parts by weight, cement 10-40 parts by weight, gypsum 2-
25 parts by weight. If the content of the siliceous mineral is less than 40 parts by weight, the water absorption cannot be improved, and the molded product is contracted during the production of the molding die, and it is difficult to remove the die from the die for molding, and cracks are likely to occur. On the other hand, if it exceeds 70 parts by weight, the curing rate of the slurry may be slow and the strength may be lowered.

If the content of cement is less than 10 parts by weight, the durability, mechanical strength and heat resistance cannot be improved, and if it exceeds 40 parts by weight, the water absorption becomes poor.

If the amount of plaster is less than 2 parts by weight, the shrinkage of the binary mortar of siliceous mineral and cement cannot be prevented, and a homogeneous compact (molding die) cannot be obtained.
On the other hand, if the amount exceeds 25 parts by weight, it is not possible to suppress the variation of the volume in the space of the molding surface, and the molding accuracy and durability deteriorate.

The present invention has the above material composition and an average particle size of 0.
Silica fine particles of 1 μm or more and less than 2 μm and / or fibrous minerals can be blended. In the present invention, only the above-mentioned siliceous fine particles may be blended, or only fibrous minerals may be blended, or both may be blended together. In any case, the amount of siliceous fine particles is 1 to 10 parts by weight, and the amount of fibrous mineral is 0.2 to 5 parts by weight. If the amount of the silica fine particles is less than 1 part by weight, the water absorption cannot be improved. On the other hand, if it exceeds 10 parts by weight, the amount of mixed water becomes large in order to impart appropriate fluidity to the slurry, leading to a decrease in strength of the molded body (molding die). When the amount of the fibrous mineral is less than 0.2 parts by weight, there is no homogeneous dispersion effect of each material, and a homogeneous molded body (molding die) cannot be obtained.
If the amount exceeds 5 parts by weight, the amount of water mixed becomes large in order to impart appropriate fluidity to the slurry as in the case of silicic acid fine particles, leading to a decrease in strength of the molded body (molding die), and further hardening takes a long time. It costs. In the sense that the porous characteristics of the molding die of the present invention are well adjusted, it is preferable to incorporate both the above-mentioned siliceous fine particles and the fibrous mineral.

Although the molding die of the present invention is a porous body, the present invention can obtain a porous body having extremely fine pores by containing a siliceous mineral, whereby a high water absorption performance can be obtained. Obtainable. Further, by adding silicic acid fine particles having an average particle diameter of 0.1 μm or more and less than 2 μm to the material composition, a porous body having a finer pore structure can be obtained, and the total pore specific surface area is increased. Thus, the water absorption performance can be further improved. Moreover, the surface roughness of the molding die is smoothed by containing the siliceous fine particles. Furthermore, since the pozzolanic reaction that occurs between the siliceous fine particles and the cement proceeds early, the siliceous fine particles have the effect of accelerating the curing speed of the molded body (molding die) in the molding die manufacturing process. The above-mentioned action of the siliceous fine particles is remarkably exhibited especially in silica fume.

Since the cured product produced by the pozzolanic reaction between the siliceous mineral and the cement, which is the constituent material of the present invention, is a water-insoluble substance, the molding accuracy and durability can be improved. That is, when molding a ceramic body using the molding die of the present invention, the molding die absorbs water from the molding material such as clay, slurry, etc. to be in a wet state, but the molding die is a siliceous mineral. Since it is a cured product of the pozzolanic reaction with cement, that is, it is made of mortar, it exhibits water-insoluble properties, so that the molding surface is prevented from being dissolved by water.

The constituent material of the present invention contains gypsum, and this gypsum is soluble in water, but since the water-insoluble mortar substance forms the basic skeleton of the molding die, the gypsum dissolves in water. However, the basic skeleton of the mold does not dissolve in water and does not physically change. Therefore, even if the ceramic body is repeatedly molded using the same molding die, and the number of molding times is large, the space volume of the molding surface of the mold hardly fluctuates, and as a result, many pieces are manufactured. As for the ceramic base material, uniform shape and size can be obtained without any error. 40-70 parts by weight of siliceous mineral, 10-40 parts by weight of cement, gypsum 2
The material composition of ˜25 parts by weight surely brings about such effects.

Since the present invention contains siliceous minerals and cement in the constituent materials, a pozzolanic reaction occurs in the presence of water in the manufacturing process of the molding die, and a hardened body of needle-like crystals is obtained due to a decrease in water content. . As described above, since the present invention is a mortar structure, it has the above-mentioned water-insoluble property, and is excellent in abrasion resistance and mechanical strength, and further in heat resistance compared with the conventional gypsum mold. Improve to.

In the present invention, gypsum is contained in the constituent material, and this gypsum has a good dispersibility, so that it has an effect of uniformly dispersing each material in the slurry in the manufacturing process of the molding die. If the dispersion of each material in the slurry is non-uniform, the resulting molded body (molding die) will also be structurally non-uniform, resulting in poor strength, water absorption performance, heat resistance and the like.

Although hardening of cement takes some time, addition of gypsum shortens the hardening time. As a result, the shape retention strength of the molded body (molding die) is imparted at an early stage, so that the manufacturing time can be shortened and the manufacturing efficiency can be improved. In the present invention, since the siliceous mineral has a fine particle diameter of 2 to 100 μm, there is a problem that the two-component mortar of siliceous mineral and cement contracts. However, the present invention is a constituent material. Since gypsum is added, it is possible to prevent such shrinkage due to the action of gypsum, and it is possible to obtain a molding die having excellent dimensional accuracy.

In general, when a ceramic body is manufactured by casting using a molding die, the releasability when the molded body is removed from the molding die becomes a problem. In the present invention, divalent calcium ions are present on the mold surface during cast molding, and the divalent calcium ions have a function of aggregating the clay particles, so that the mold releasability of the molding base is improved. Gypsum serves as a source of such divalent calcium ions.

As described above, gypsum has the function of uniformly dispersing each material in the slurry during the production of the molding die of the present invention. However, by incorporating a fibrous mineral in the present invention, the content of each material in this slurry can be improved. It has an effect of further improving the uniform dispersion. That is, the fibrous mineral has a large specific surface area, possesses water of crystallization, and has a high hydrophilicity,
Disintegration process in water gives a highly viscous and stable dispersion solution, which restrains the movement of each material particle in the slurry, so that each material can be uniformly dispersed, thereby forming a molded body (molding die). There is an effect that can contribute to homogenization and stabilization of.
Further, the fibrous mineral also has an action of preventing shrinkage of the manufactured molded body (molding die). The action of such fibrous minerals is remarkably exhibited especially in sepiolite.

A preferred embodiment of the present invention is siliceous mineral, cement, gypsum, having an average particle size of 0.1 μm or more and 2 μm.
That is, the molding die is formed of a material composed of silicic fine particles of less than m and fibrous mineral. According to such a configuration, the siliceous mineral serving as the supply source of the silicic acid component consumed in the pozzolanic reaction is characterized in that the siliceous fine particles are extremely fine particles, and by the action of gypsum and the fibrous mineral,
There is a feature that each material in the slurry can be uniformly dispersed even if the amount of water is increased. Due to these features, a porous hardened body (molding die) with a large total pore specific surface area can be obtained. Thus, a molding die having excellent water absorption performance can be obtained.

Table 1 shows the chemical analysis values of ordinary Portland cement, silica stone, feldspar, gypsum, silica fume, sepiolite and attapulgite which can be used as the constituent material of the present invention.

[0040]

[Table 1]

In Table 1 above, Ig. Loss means ignition loss, and tr means a trace amount.

In producing the molding die of the present invention, 40 to 70 parts by weight of siliceous mineral and 10 to 40 of cement are used.
Parts by weight, gypsum 2 to 25 parts by weight, silica particles having an average particle size of 0.1 μm or more and less than 2 μm, 1 to 10 parts by weight, fibrous minerals 0.2 to 5 parts by weight, and water 35 to 60 parts by weight. The resulting slurry is mixed and cast into the molding space of the mold for molding, cured, and demolded to obtain a molded body (molding die). As described above, the amount of water blended is 35 to 60 parts by weight. If the amount of water blended is less than 35 parts by weight, the fluidity of the slurry will be reduced, and defoaming will be hindered. Is noticeable, and there is a possibility that an unfilled portion may occur when the slurry is filled in the mold (mother mold). On the other hand, when it exceeds 60 parts by weight, the specific gravity of the slurry becomes low, the constituent materials are separated, the materials in the slurry are not uniformly dispersed, and the homogeneity of the obtained molded body (molding die) is not maintained, It becomes unsuitable as a molding die.

Next, a method for manufacturing the molding die of the present invention will be described with reference to FIG. The molding die of the present invention is manufactured according to the following steps. 1) Dry primary mixing First, a siliceous mineral raw material is wet pulverized, classified and dried to obtain a siliceous mineral material. This is mixed with cement to perform a dry primary blending (this blended one is referred to as a primary blend). 2) Wet-dispersing the siliceous fine particle material to obtain a siliceous fine particle suspension. 3) Wet disintegration treatment of the fibrous mineral material to obtain a fibrous mineral suspension. 4) Wet Secondary Mixing The above primary preparation, water, gypsum, the above siliceous fine particle suspension and the fibrous mineral suspension are mixed, and a homogeneous slurry is obtained by this wet secondary mixing. 5) Defoaming step The bubbles in the slurry are removed by vacuum stirring. 6) Molding process Mold Assembling the parts of the molding master to make the master, applying the release agent to the inner surface of the master, pouring the slurry into the mold from the casting opening of the master, and leaving it for a certain period of time. To cure the slurry. 7) The molded product obtained by demolding is removed from the mother mold. In this case, it is possible to easily remove the mold by sequentially removing the parts of the mother die. 8) After demolding the demolded molded body, it is dried.

The molding die of the present invention is manufactured by the above steps.

When the molding die of the present invention is subjected to X-ray diffraction,
The peaks of the siliceous mineral component and the gypsum component clearly appear, but the peaks of the cement component do not clearly appear and become broad.

The molding die of the present invention does not dissolve the molding surface by the water absorbed from the molding material when molding the ceramic body, and the water-insolubilized structure allows the molding surface to have a space volume within the molding surface even when the molding is repeated many times. It is possible to prevent the phenomenon of gradually increasing. Further, the molding die of the present invention has excellent wear resistance, and does not easily wear when subjected to a large stress due to the spatula of the clay and the clay holding jig when the roller machine molding or the rokuro molding is performed. Due to such water-insolubilizing property and wear resistance property, the volumetric capacity of the molding surface after molding many times hardly changes, whereby molding accuracy can be improved and excellent durability as a molding die can be realized.

Further, the molding die of the present invention has a large mechanical strength, is not easily damaged by an external force, and is convenient in handling.

Moreover, the molding die of the present invention is excellent in heat resistance, and the drying temperature for repeatedly using the molding die of the present invention moistened by molding is not particularly limited. As a result, unlike the conventional case, there is no restriction on the drying temperature of 41 ° C. or less, and the drying temperature can be shortened and the manufacturing efficiency can be increased.
The preferred drying temperature in the present invention is 40 ° C to 80 ° C.

The present invention is applicable to cast molding, roller machine molding,
It is preferably used as a mold for molding such as rokuro molding.

Next, examples of the present invention will be shown.

Example 1 Each material was prepared according to the process shown in FIG. 1 by the material composition shown in Table 2 to prepare a mixed slurry. The numerical values in Table 2 show parts by weight. Also, as silica stone, the average particle size is 4
The thing with a micrometer was used. According to the process shown in FIG. 1, the mixed slurry was poured into a die for molding and hardened to form a molded body, which was then demolded and the molded body was taken out from the mold to manufacture a ceramic molding die. By the various formulations shown in Table 2, six types of molding dies of the present invention of N type 1, N type 2, N type 3, N type 4, N type 5 and N type 6 were obtained. Table 3 shows the physical properties of the obtained molding dies. For the purpose of comparison, the compositions of gypsum mold 1 (comparative example 1) which is a commercially available casting mold and gypsum mold 2 (comparative example 2) which is a commercially available roller machine molding mold are shown in Table 2, and The physical properties thereof are shown in Table 3.

[0052]

[Table 2]

[0053]

[Table 3]

According to Table 3, N types 1 to 6 are gypsum types 1 and 2.
Has a smaller average pore diameter and a larger total pore specific surface area. As a result, the N types 1 to 6 have significantly higher water absorption than the gypsum types 1 and 2.

Example 2 N-types 1 to 6 and gypsum types 1 and 2 were immersed in a water tank containing colored water, and the wet height was measured 10 minutes after the immersion as the diffusion rate of water. The results are shown in Table 4.

Further, a ceramic body was molded using each mold. At the time of this molding, a slurry for producing ceramics having a water content of 30% was used, and the slurry was cast into a mold for casting. At this time, the thickness of the formed body was measured. Ten molded bodies were made with one mold, the thickness of each wall was measured, and the average value was calculated. Further, the mold releasability at the time of releasing the molded body was tested. The results are shown in Table 4.

Further, a comprehensive judgment was made as to what kind of molding each mold is best used for. The results are shown in the column of "Application by molding" in Table 4.

[0058]

[Table 4]

From the results shown in Table 4, it has been found that the molding die of the present invention can produce a ceramic base under the same molding conditions and molding steps as those of the conventional gypsum mold. That is, it has been found that a good ceramic base can be manufactured without providing special molding conditions and molding steps different from the conventional ones.

Example 3 In the case of a large-sized or thick-walled ceramic green body, it is necessary that the thickness of the wall in the vertical direction be uniform. Also in the above, that is, the porosity of the molding die is required to be homogeneous. Therefore, a test was carried out to see if the molding die of the present invention had a uniform water absorption capacity.

In this test, a cylindrical molded body having an N type 6 composition was prepared. That is, a slurry having the material composition of N type 6 shown in Table 2 was cast into a mold and cured to form a cylindrical molded body having a height of 40 cm and a diameter of 8 cm. The physical properties of the porous body were measured at three sites, the upper part, the middle part, and the lower part of the molded body. The results are shown in Table 5.
Shown in.

[0062]

[Table 5]

According to Table 5, the N-type 6 cylinder is at the top,
It shows that the central part and the lower part have uniform physical properties. From this, the molding die of the present invention has a uniform water absorption capacity in the longitudinal direction (upper portion, middle portion, and lower portion) of the die, and as a result, it is possible to produce a molded body having a uniform thickness in the longitudinal direction. It was confirmed to be a thing.

Example 4 Using the material composition of N type 4 shown in Table 2, a molding die for producing a dish was manufactured according to the process shown in FIG. Using this molding die, 200 10-inch dish-shaped substrates were molded. The weight of the molding die before molding (that is, the number of molding times is 0) and after molding 200 of the above-mentioned base materials (that is, the number of molding times is 200).
The weight of the molding die was measured, and the “weight ratio after molding” was calculated by showing the ratio of the weight after 200 moldings to the weight before molding as a percentage (%). In measuring the weight of the mold, the mold was dried at 40 ° C. and the dry weight was measured. For comparison, a gypsum mold for making a dish having the composition of gypsum mold 2 shown in Table 2 was manufactured, and the same test as above was performed to determine the weight ratio after molding.

As a result, in the N type 4, the mold weight before molding was 3926 g, and the mold weight after molding 200 pieces was 392.
It was 4 g. Therefore, the weight loss rate was 0.05%, and the weight ratio after molding 200 pieces, that is, the weight ratio after molding was 99.95% with respect to the weight before molding.

On the other hand, in the gypsum mold 2, the mold weight before molding was 3287 g, and the mold weight after molding 200 pieces was 3202 g.
It was g. Therefore, the weight loss rate was 2.59%, and the weight rate after molding was 97.41%. Based on the above results, the relationship between the number of moldings and the weight ratio after molding is shown in the graph of FIG. In the figure, 1 indicates an N type 4 and 2 indicates a gypsum type 2.

The above-mentioned test was carried out by measuring the degree of wear when a large number of substrates were molded using the same mold.
The N-type 4 had a very small degree of wear even after the molding of 200 bases, which is a practical upper limit, and it was found that the N-type 4 had a durability of slightly more than 50 times that of the gypsum type 2.

[0068]

EFFECTS OF THE INVENTION The present invention comprises a mold for ceramics made of a material composed of siliceous minerals, cement, and gypsum, and therefore has a water-insoluble skeleton structure, and therefore the ceramic base molding is repeated many times. However, the internal volume of the molding surface does not increase, and the internal volume of the space can be maintained substantially constant. As a result, even if the base material is formed a large number of times as compared with the prior art, there is almost no error in the dimensions of the formed base material, the useful life of the mold is extended, and the durability is remarkably improved. Further, since the molding die of the present invention has excellent wear resistance, fluctuations in the space volume of the molding surface are suppressed from this aspect as well, and there are two effects: the water-insoluble skeleton structure and the wear resistance. By the action, there is an effect that the durability of the mold can be dramatically improved as compared with the conventional one.

Further, the molding die of the present invention has excellent mechanical strength,
It is not easily damaged by external force. Further, the heat resistance is improved as compared with the conventional one, so that the drying temperature of the mold can be increased to shorten the drying time and the efficiency of the molding cycle can be improved.

According to the manufacturing method of the present invention, it is possible to easily manufacture a ceramics molding die having excellent characteristics by a molding step similar to the conventional one.

[Brief description of drawings]

FIG. 1 is a block diagram showing a manufacturing process of a ceramics molding of the present invention.

FIG. 2 is a graph showing the relationship between the number of moldings and the weight ratio after molding.

[Explanation of symbols]

1 N type 4 2 gypsum mold 2

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C04B 14:38)

Claims (6)

[Claims] 1. A mold for forming ceramics, which is formed of a material composed of siliceous mineral, cement, and gypsum. 2. The mold for porcelain molding according to claim 1, wherein silicate fine particles having an average particle diameter of 0.1 μm or more and less than 2 μm and / or fibrous minerals are mixed. 3. A ceramic molding die, which is made of a material composed of 40 to 70 parts by weight of siliceous mineral, 10 to 40 parts by weight of cement, and 2 to 25 parts by weight of gypsum. 4. Silica mineral 40 to 70 parts by weight, cement 10 to 40 parts by weight, gypsum 2 to 25 parts by weight, silicic fine particles having an average particle size of 0.1 μm or more and less than 2 μm, 1 to 10 parts by weight, and fibers. A mold for porcelain molding, which is formed of a material composed of 0.2 to 5 parts by weight of fine minerals. 5. Silica-based mineral 40 to 70 parts by weight, cement 10 to 40 parts by weight, gypsum 2 to 25 parts by weight and water 35 to 60.
A method for manufacturing a ceramics molding die, characterized in that parts by weight are added and mixed, and the resulting slurry is cast into a molding die, cured, and released to obtain a molded body. 6. Silica mineral 40 to 70 parts by weight, cement 10 to 40 parts by weight, gypsum 2 to 25 parts by weight, silicic fine particles having an average particle size of 0.1 μm or more and less than 2 μm, 1 to 10 parts by weight, and fibers. 35 to 60 parts by weight of water was added to 0.2 to 5 parts by weight of the fine mineral and mixed, and the obtained slurry was cast into a molding die, cured, and demolded to obtain a molded body. A method for manufacturing a ceramics molding die characterized by: