JPH11147753A - Plastic clay formulation for low-temperature baked pottery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject formulation with extremely wide baking temperature range usable for hobby ceramic art, and sufficiently firmly sinterable by its baking at <=1,000 deg.C with the shape of the molded product retained. SOLUTION: This new type plastic clay formulation for low-temperature baked pottery comprises a three-component mixture which contains kaolin or clay <=3.0 μm in average particle size and calcium carbonate fine particles <=2.0 μm in average particle size in the weight ratio of (45:55) to (75:25) and incorporated with 20-40 wt.% of relatively rough silica rock powder 3-50 μm in average particle size. This formulation in the form of molded product is readily firmly sinterable as it is, or even if mixed with other additive(s), at relatively low temperatures of <=1,000 deg.C while retaining its shape into a crystalline pottery product consisting mainly of anorthite and quartz, and also is resistant to softening and deformation even at >=1,000 deg.C, thus being extremely wide in baking temperature range.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method of sintering at a relatively low temperature of 1000 DEG C. or less, without sintering large sintering, and sufficiently hardening. The present invention relates to a plastic clay compound for low-temperature firing ceramics, which is a water-based clay having excellent properties and is useful for hobby ceramics or for general ceramics production.

[0002]

2. Description of the Related Art Conventionally, plastic clay compounds used for hobby pottery and the like require firing at a temperature of 1200 ° C. or higher in order to obtain a ceramic body having sufficient strength.
At a low temperature of about ℃, almost no sintering was performed, and only a low-strength earthenware having extremely large water absorption could be produced. As ceramics produced industrially at the lowest temperature, base materials conventionally called white cloud ceramics have been used for novelties such as large-sized and pepper shakers.
C. or higher was required, and most of them were fired at around 1100.degree. C. In general, there were none of those which were porous, had high water absorption, had extremely low strength, and had an average bending strength exceeding 60 MPa.

In order to obtain a strong ceramic body having sufficient strength by firing at low temperature, a method of kneading and molding with a large amount of vitreous powder such as a low-melting frit has been conventionally performed in a part of the method. Due to the fusion of the low-temperature molten glass, not only is it not possible to obtain sufficient strength, but also because the amount of glass is large, the molded product is softened and deformed during firing, making it difficult to maintain its shape. When the temperature is slightly increased, there is a serious drawback that a product having a precise shape cannot be obtained due to softening deformation flow. In general, firing shrinkage increases,
It is difficult to manufacture large products, and it is difficult to uniformly heat the products in a furnace such as an electric furnace because heat is transferred by radiation, especially for ceramics using a small nichrome electric furnace. It is difficult to avoid deformation and cracking due to uneven shrinkage, and at a low temperature of 1000 ° C or less, and by firing for a relatively short time, it produces a stable ceramic body that is firmly burnt tight enough to hit and produce a high clear sound. Doing so far has never been possible.

[0004]

Accordingly, the present invention relates to an industrially inexpensive raw material such as kaolin or clay mainly containing kaolinite or halloysite and calcium carbonate and silica powder, which are most commonly used as ceramic materials. The main component is that the molded product is easily and firmly sintered at a relatively low temperature of 1000 ° C or less, that is, the temperature of a simple nichrome wire electric furnace, and the average bending strength is sufficiently high. The relatively small temperature makes it difficult to generate deformation and cracks even for relatively rapid temperature rise for ceramics or for relatively large products such as for construction. Also, the firing temperature range is extremely wide, and the temperature is over 1000 ° C. It is hard to be softened and deformed even when it becomes high, the firing method is almost no problem, it is extremely suitable for amateur pottery and teaching materials, a completely new characteristic low It is intended to provide a sintered ceramic thermoplastic formulations.

[0005]

Therefore, in the present invention, kaolinite or halloysite fine particles and calcium carbonate fine particles having an average particle diameter of 2.0 μm or less are mixed in a weight ratio of 4%.
5:55 to 75:25, and 20 to 40 wt. Of silica powder having an average particle size of 3 to 50 μm.
% Of the three-component mixture added as a basic component, and the molded body is sintered at a relatively low temperature of 1000 ° C. or less, and has a firing shrinkage of 15% or less and an average bending strength of 60 MPa or more. , A crystalline ceramic body mainly composed of anorthite and quartz, and is hardly softened and deformed even at 1000 ° C. or more, and has a very wide firing temperature range.

Further, kaolinite or halloysite fine particles and calcium carbonate fine particles having an average particle size of 2.0 μm or less are contained in a weight ratio of 45:55 to 75:25, and the average particle size is 3%. A mixture containing 90% or more of a three-component mixture containing 20 to 40% by weight of silica powder of about 50 μm as a basic component is further divided into 40 parts.
It is a mixture to which a coarse powder of inorganic crystal or glass having an average particle diameter of 50 to 200 μm of not more than wt% is added, and the formed body is sintered at a relatively low temperature of not more than 1000 ° C. Moreover, it is a crystalline ceramic body mainly composed of sufficiently strong anorthite and quartz, and is hardly softened and deformed even at 1000 ° C. or more, and has a very wide firing temperature range.

[0007]

The present inventors have prepared a finely divided elutriated kaolinite or halloysite-based fine kaolin or clay and calcium carbonate fine powder having the following chemical compositions:
In a composition in which the CaO content after firing is 15 to 42%, if the average particle size of calcium carbonate is sufficiently small to be 2.0 μm or less, the thermal decomposition products of kaolin and calcium carbonate may be generated during the firing process. Solid solution progresses, 800-9
In a very narrow temperature range of 00 ° C., solid solution formation was found to be almost completed before silicate crystal precipitation, and the product at this stage was an aggregate of amorphous fine particles containing an appropriate amount of CaO. Yes, with extremely high viscosity, maintaining the molded shape, with remarkable low-temperature sintering, 875 ° C to 950 ° C
I discovered that it became more compact.

FIG. 1 shows the result of this basic experiment.
A slurry of high-purity halloysite obtained by elutriation-purifying New Zealand kaolin to a particle size of 1.0 or less and fine powder obtained by preliminarily ball milling high-purity limestone to an average particle size of 1.5 μm in various mixing ratios And then dehydrated and dried to obtain a number of powdered plastic clay compounds having different compositions. Pellets having a diameter of about 16 mm were formed by a dry press at a molding pressure of 1 ton / cm ² , and the pellets were placed in an electric furnace at 900.degree. The result of baking at ℃ for 1 hour is shown. It can be seen that the sintering activity is extremely high when the chemical composition after calcination is 15 to 42 wt% as CaO. For comparison, a case where 20% of silica powder having a particle size of about 2 μm was added and mixed was also shown. However, the similar sinterability was almost similar to the addition of silica powder, and the content of CaO was particularly large. It is effective in a wide range of cases. These proportions correspond to the weight ratio of fine kaolin to calcium carbonate in the range of 45:55 to 75:25 when represented by the mixing ratio of the raw materials before calcination, that is, before pyrolysis, which is the basis of the present invention. Condition.

The present inventors have further found that the composition having the above-mentioned compounding ratio exhibits a sintering promoting effect even when mixed with other inorganic material particles, and becomes a strong sintered body at a low temperature. It has been found that silica exhibits excellent characteristics. That is, the silica particles having an average particle diameter of 3 to 50 μm are advantageous in moldability and formability, and even when the calcination shrinkage is suppressed by adding a relatively large amount, the calcination product at a temperature of 1000 ° C. or less is still high. It turned out to give a stable ceramic body firmly baked to the extent that it produces a clear sound. In addition, the addition of silica promotes the crystallization of the base material and further enhances the shape stability, and it does not easily deform or crack due to uneven temperature distribution or excessive rise in furnace temperature due to rapid rise in furnace temperature. It also turned out to be a plastic clay for use.

[0010] The reaction in the calcination process mainly occurs between the kaolin decomposed product and the calcium carbonate decomposed product, and coarse silica particles react only slightly on the particle surface. The above mixing ratio of calcium carbonate determines the type and ratio of the final precipitated crystals. Even in the presence of silica, most of the silica remains, and at a temperature of about 900 ° C. or more, crystals such as anorthite, gehlenite, and orastonite precipitate, and these crystal particles prevent the softening deformation of the molded product, and the firing temperature range Is extremely wide. In general, the larger the amount of calcium carbonate is, the better the low-temperature sinterability is. However, if the weight ratio of calcium carbonate to kaolin is more than 45:55, crystals of gehlenite tend to precipitate before densification. The sinterability deteriorates, and the water resistance of the product deteriorates, which makes the product unsuitable for practical use. Further, with calcium carbonate having a weight ratio of less than 75:25, the amount of CaO solid-solutioned in the amorphous phase is insufficient, so that the sinterability at 1000 ° C. or less is insufficient, and sufficient strength may be obtained. It will be difficult.

The particle size range of the raw material is a very important factor of the present invention, and kaolin or clay has at least an average particle size of 3.
It is necessary to perform elutriation purification to 0 μm or less, and it is most important that calcium carbonate is extremely fine. In the case where the average particle size of calcium carbonate in the composition is 1.5 μm, a sufficient reaction takes place between the kaolin calcium carbonate pyrolysates in the low temperature region at the time when the pyrolysis is completed within the above range of the mixing ratio. As a result, the formation of a solid solution proceeds, so that the sinterability is fully exhibited. However, the average particle size of calcium carbonate, which is usually used as a ceramic material, is 2.5 μm.
In the above case, the solid solution forming reaction was insufficient, so that a strong sintered body was not obtained, and only a material having low strength was obtained. That is, the most important requirement is that the average particle size of calcium carbonate is 2 μm or less.

On the other hand, 3 to 50 μm silica powder particles are
It is added for the purpose of reducing firing shrinkage while maintaining high strength, and it is necessary that the action of the easily sinterable component is not significantly impaired. As a result of comparing many mineral powders, silica stone (quartz, SiO ₂ ) was the most effective, and the strength was maintained even when added in the largest amount. Since CaO is a basic oxide, a part of the particle surface reacts with CaO even if a relatively large amount of acidic oxide such as silica (SiO ₂ ) is added,
It is considered to be most suitable for maintaining strength.

Here, silica can reduce the firing shrinkage,
There is an advantage that the operability of the kneaded material is improved, the firing deformation is reduced, and the raw material cost is reduced because the clay is extremely inexpensive. However, in the case of particles having an average particle diameter of about 3 μm or less obtained by ordinary ball mill pulverization as generally used, the addition of a large amount results in a decrease in plasticity, resulting in an increase in firing shrinkage. The firing shrinkage is impaired. Also, coarse silica powder having a size of 50 μm or more impairs the homogeneity of the base material, lowers the strength of the fired ceramic body, and is not suitable when strength is required. Therefore, the silica powder as a medium-grain component of 20 to 40 wt% of the present invention is required to have an average particle size in the range of 3 to 50 μm. It is most suitable for increasing the amount of addition while maintaining strength.

The three-component mixture in which the particle size of kaolin or clay, calcium carbonate and quartzite powder is limited is a basic component of the present invention, and includes the addition of a ceramic pigment for coloring the substrate and a balloon for reducing the weight. Of course, it is possible to add and mix various additives used in ordinary ceramic techniques, but in order to obtain a ceramic body having a bending strength of 60 MPa or more, at least 9 of the basic components are required.
It is necessary to account for 0% or more.

However, the plastic clay composition of the present invention is characterized by containing a relatively large amount of calcium carbonate having a particle size of 2 μm or less, so that the plastic clay is not suitable for manual pottery.
There are some deficiencies in moldability. The molded product from the three-component mixture of the present invention has an average bending strength of 60 MPa or more, which is extremely high as compared with ordinary water-absorbing porcelain. It is easy to improve the properties. Especially for amateur pottery, if the firing shrinkage ratio is further reduced and emphasis is placed on shape stability,
Workability such as potter's wheel molding may be important, and in such a case, 50 to 20 more
Coarse particles of 0 μm can be added and mixed up to 40% by weight. That is, the three-component mixture in which the particle size of kaolin or clay, calcium carbonate, and silica stone powder is limited, exerts a sufficient effect as a binder on appropriate coarse particles.

As the coarse particles, those which intervene in the matrix of the present invention comprising a mixture of three or less medium particles and which do not significantly reduce the strength are suitable. Coarse particles such as site-based selven can be used economically and practically. All of these have a high affinity with the matrix, maintain a bonding strength at the grain boundary, and become a ceramic body having sufficient strength for practical use, can be potter's wheel formed, and can suppress firing shrinkage to within 10%. become able to. Therefore, even in an electric furnace having a relatively rapid temperature rise and a relatively poor temperature distribution, no deformation or cracking of the molded product occurs at all, and a large molded product can be relatively easily fired at a low temperature. is there.

Conventionally, the most common ceramic is feldspar-like,
Sintering depends on the low-temperature fusibility of feldspar, but no sintering effect can be exhibited at 1000 ° C or lower. In addition, glass powder that melts at a low temperature generally has a remarkable effect on low-temperature sintering of ceramic bodies, but as described above, in principle, it promotes sintering and densification by forming a liquid phase. In addition, there is a serious drawback in that the compact is softened and deformed by the liquid phase during the densification process, and it is extremely difficult to maintain the shape. On the other hand, the low-temperature sintering in the present invention is based on a mechanism different from porcelain formation, that is, vitrification, and therefore, it is characterized in that the ceramic body after firing is almost crystalline only. That is, sintering and densification of the fine-grained component for low-temperature sintering does not require the formation of a liquid phase. Therefore, in addition to the addition of the silica powder, the addition of a small amount of glass powder to such an extent that the glass powder does not undergo softening deformation has the effect of lowering the firing temperature without significantly impairing the shape stability during firing. In addition, when coarse powder particles of glass or silica are mixed with the conventional ceramic body, the crescent-shaped micro-cracks are generated on the surface of the quartz particles due to the softening deformation caused by glass as described above, and the strength is significantly increased. Although there was a disadvantage of lowering, the sintering of the fine-grained component became a sintering strengthening mechanism in the present invention, and thus such cracks were not observed by electron microscope observation. ,

Hereinafter, the production method of the present invention will be described in more detail with reference to laboratory examples, but the present invention is not limited thereto.

[0019]

Example 1 New Zealand kaolin was used as a raw material kaolin. This is a relatively high-purity kaolin containing halloysite as a main component, its chemical composition is% by weight,
iO ₂ : 49.78, Al ₂ O ₃ : 35.72, Fe ₂
O ₃ : 0.26, TiO ₂ : 0.12, CaO: tr,
MgO: tr, K ₂ O: tr, Na ₂ O: 0.06, loss on ignition: 14.05, which is somewhat higher in SiO ₂ than the ideal kaolinite composition. Limestone (chemical composition is almost 100 wt% CaCO ₃ ) finely pulverized in advance so that the average particle size of the kaolin is 1.5 μm,
Using silica (quartz) powder having an average particle size of about 10 μm, the components are blended in a mixing ratio corresponding to each point of triangular coordinates of kaolin, calcium carbonate, and silica as shown in FIG. An earthy plastic clay formulation was obtained. Using these clay compounds, a thin rod-shaped sample having a diameter of 2.0 mm was formed by an extruder and fired at 950 ° C. for 1 hour in air using a nichrome wire electric furnace. Regarding the obtained sintered body, those whose average bending strength is 60 MPa or more but firing shrinkage is 15% or more are marked with a circle, and firing shrinkage is 15% or less but the average bending strength is 60M.
Samples having a Pa or less were indicated by a mark, and samples having a firing shrinkage of 15% or less and an average brilliance of 60 MPa or more were indicated by a mark. The shaded portion in FIG. 2 is the composition region of the present invention.

[0020]

Example 2 Using the same New Zealand kaolin and calcium carbonate as in Example 1, the mixing ratio of kaolin and calcium carbonate is 60:40 (corresponding to 70:30 by weight ratio of anhydrous kaolin and CaO). Then, 5 to 50 wt% of silica powder having an average particle size of about 10 μm is added to each of them, and each is made into a slurry, and then sufficiently ultrasonic-mixed, dewatered and kneaded, and dried to obtain a composition. A number of different powdered plastic clay formulations were obtained. Using these clay compounds, dry press to 1t
Pellets each having a diameter of about 16 mm were formed at a forming pressure of on / km ² and fired at 1000 ° C. for 1 hour in an electric furnace.

The firing shrinkage of the obtained sintered body, as shown in FIG.
Although the shrinkage rate is so large that it becomes difficult to control the dimensions and shape, which is a problem in the manufacturing process, it decreases remarkably with the increase in the silica content, and becomes almost the same as general porcelain products with the addition of 20 wt%. It can be seen that the addition of more than this results in a shrinkage of 15% or less and an increase in shape stability.

A round rod having a diameter of about 5 mm is extruded from the clay of the above-mentioned silica-added clay composition by extrusion, and a sample rod having a length of 50 mm is prepared. , 950 ° C and 1000 ° C for 1 hour. FIG. 4 shows the degree of sagging of the bridge in the obtained sintered body. From FIG. 4, it can be seen that if the addition of the silica powder exceeds 20 wt%, the sintered body hardly undergoes any softening deformation at 1000 ° C. It is considered that this is because not only silica becomes an aggregate but also the crystallization of the amorphous portion is promoted by the presence of the silica in the result of the X-ray diffraction of the sample.

[0023]

Example 3 The same New Zealand kaolin and calcium carbonate as in Example 2 were blended at a ratio of 60:40, and the average particle size was about 1.0 μm to 50 μm.
m, 5 types of silica powder having different particle sizes
wt%, each was made into a slurry, and then sufficiently subjected to ultrasonic mixing and dewatered and kneaded to obtain a large number of clays of a plastic clay compound. Using each of these clay compounds, a round bar with a diameter of about 2 mm was extruded by extrusion,
Each was fired at 900 ° C. and 1000 ° C. for 1 hour in air.

FIG. 5 shows the measurement of the firing shrinkage and the average bending strength. When the average particle diameter of silica is 2 μm or less, sintering does not proceed sufficiently at a sintering temperature of about 900 ° C., the sintering shrinkage is small, but the average bending strength is insufficient. Firing shrinkage is 15
%. The average particle size of the silica is 50 μm
It can be seen that the average bending strength gradually decreases with the coarseness.

[0025]

Embodiment 4 In a further practical embodiment of the present invention,
The main raw materials are commercially available high quality Kibushi clay, limestone, and silica stone, and some ceramic pigments for coloring are used. Limestone used is finely ground in advance so that the average particle size is 2 μm or less. Silica powder is a commercially available product with an average particle size of about 200 μm.
m were directly used, blended in the respective weight ratios shown in Table 1, and crushed and mixed for 6 hours by ball milling in a relatively short time so that the average particle diameter of silica was not reduced to 3 μm or less. Adjusted color clay. By the short-time ball mill mixing, the particle size of the silica was about 3 to 15 μm from observation of the polished surface with an electron microscope.

[0026]

[Table 1]

All of the samples shown in the table have sufficient plasticity to be able to perform potter's wheel molding in the state of the kneaded soil, and all of the plastic molded articles are kept at 900 ° C. for about 3 hours in a small nichrome wire electric furnace. It was possible to obtain a strong ceramic body without deformation or cracking due to rapid temperature rise. Since the firing temperature is low, the ceramic pigment remains almost unchanged without reacting, so that all become beautiful pastel-colored colored ceramic bodies. If D sample and E sample are mixed, two kinds of pigments, pink and navy blue, are obtained. The characteristics such as a purple ceramic body can be obtained by maintaining the mixed color of as is. Naturally, all of these could be made into glazed pottery by applying transparent frit glaze. Among them, for the kneaded material of the A, B and C samples, a round bar having a diameter of about 2 mm was extruded by extrusion, respectively, and fired shrinkage rate when fired in air at 850 to 1100 ° C. for 1 hour, respectively, and The measurement results of the average bending strength are shown in FIG. For comparison, a similar test was carried out for the low-temperature fired Baiyun pottery base material that is currently being produced, and the results are shown in the figure. Compared to the current Baiyun pottery,
The outstanding features are evident, and the strength is clearly shown to exceed that of general feldspathic porcelain.

The other samples were also measured in air at 850.
Each was fired at 〜1100 ° C. for one hour, and the firing shrinkage and the water absorption were measured. The results are shown in FIG. In all of these samples, plasticity, workability, firing shrinkage, etc. can be easily improved while retaining sufficient strength for practical use while sacrificing some strength by mixing coarse particles such as silica stone. . In FIG. 8, commercially available glass beads having a diameter of about 100 μm are added to the sample D, and the mixture is made sufficiently uniform by adding 10, 20 and 40%.
The firing shrinkage when firing at 0 ° C. for 1 hour is shown. In general, it is natural that the water absorption rate increases due to the incorporation of coarse particles, the firing shrinkage rate decreases, and the shape stability during firing further improves.However, in this case, the strength is maintained by kaolin or clay or carbonate. It is based on a basic component consisting of a three-component mixture in which the particle size of calcium and silica powder is limited, and all of them produce a high clear sound when hit, resulting in a ceramic body that can withstand practical use.

[0029]

In the past, plastic clays used for hobby ceramics and the like generally require a firing temperature of 1200 ° C. or higher.
At a temperature of 000 ° C or less, it was possible to obtain only earthenware which had almost no densification at all and had water absorption. By a new idea, kaolin or clay and calcium carbonate, which are most commonly used as ceramic materials, were used. Ingredients such as industrially inexpensive raw materials as the main component, the necessary additives are blended as appropriate, excellent plastic moldability, very low temperature of 1000 ℃ or less, that is, the temperature of a simple nichrome wire electric furnace, Provided is a plastic clay capable of forming a strong ceramic body having a relatively small water absorption rate while maintaining a formed shape. Therefore, even if the colorability is low due to low temperature firing, the firing temperature is too high, or if high temperature treatment is required for other purposes such as glazing, the simplification of firing does not require special knowledge such as a wide firing temperature range. Such excellent workability is extremely useful for pottery purposes, and can be simultaneously fired in combination with a metal material such as silver or nickel, thereby enabling a completely new product both for building use and industrially.

[Brief description of the drawings]

FIG. 1 is a diagram showing the relationship between the compounding ratio indicating the composition range of sintering activity of kaolin and fine particle calcium carbonate, which are the basis of the present invention, and the apparent porosity after firing at 900 ° C.

FIG. 2 is a diagram showing the relationship between the composition range of the present invention, the firing shrinkage after firing at 950 ° C., and the average bending strength.

FIG. 3 shows 900 samples of various samples of the present invention having different amounts of silica mixed therein.
FIG. 4 is a relationship diagram of a firing shrinkage rate of a fired product at 1 ° C. for 1 hour.

FIG. 4 shows 900 samples of various samples of the present invention with different amounts of silica mixed therein.
FIG. 3 is a relationship diagram of a firing softening deformation rate of a fired product at 1 ° C. for 1 hour.

FIG. 5 is a graph showing the relationship between the firing shrinkage ratio and the average bending strength of silica gel powders of various average particle sizes according to the present invention, which are fired at 900 ° C. and 1000 ° C. for 1 hour each for the silica particle size.

FIG. 6 is an example in which color clay is used as an application example of the present invention.

850 ° C., 900 ° C., 1000 ° C.,
FIG. 1 is a diagram showing the relationship between the firing shrinkage of a fired product at 1100 ° C. for 1 hour and the average bending strength.

FIG. 7 is an example in which color clay is used as an application example of the present invention.

850 ° C., 900 ° C., 1000 ° C.,
And FIG. 1 is a relationship diagram of a firing shrinkage rate of a fired product for 1 hour at 1100 ° C. and a water absorption rate.

FIG. 8 shows an embodiment in which color clay is used as an application example of the present invention.

FIG. 4 is a graph showing the relationship between firing shrinkage ratios when a mixture obtained by adding 10, 20, and 40 wt% of glass beads having a diameter of 100 μm to the sample D in Table 1 was fired at 900 ° C. for 1 hour.

Claims (2)

[Claims] (1) The composition contains kaolinite or halloysite fine particles and calcium carbonate fine particles having an average particle diameter of 2.0 μm or less in a weight ratio of 45:55 to 75:25. It contains 90% or more as a basic component of a ternary mixture to which 20 to 40% by weight of silica powder of 3 to 50 μm is added. % Or less, and has a strong average bending strength of 60 MPa or more, is a crystalline ceramic body mainly composed of anorthite and quartz, and is hardly softened and deformed even at 1000 ° C. or more, and has a very wide firing temperature range. Low temperature firing plastic clay compound for porcelain. 2. A composition comprising kaolinite or halloysite microparticles and calcium carbonate microparticles having an average particle size of 2.0 μm or less in a weight ratio of 45:55 to 75:25. A mixture containing 90% or more of a three-component mixture obtained by adding 20 to 40% by weight of silica powder of 3 to 50 μm as a basic component is further divided into 40% by weight.
% Or less of a coarse powder of inorganic crystals or glass having an average particle size of 50 to 200 μm or less.
Sintering at a relatively low temperature of 00 ° C or less, with a firing shrinkage of 1
A plastic porcelain for low-temperature firing porcelain, characterized in that it is a crystalline porcelain body mainly composed of anorthite and quartz which is not more than 0% and is sufficiently strong. Stuff.