JPH11199311A - Production of clay ceramic and caly ceramic - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a clay ceramic with freezing damage resistance and low contraction and low water absorption by mixing together feedstocks comprising talc, clay, cullet, feldspar, silica sand and/or chamotte in specific proportions followed by molding and then baking. SOLUTION: First, feedstocks comprising 40-65 wt.% of tale as the main stock for steatite green body, 5-30 wt.% of clay such as kibushi-clay as molding auxiliary, 5-45 wt.% of pref. soda ash glass such as plate glass cutlet, 0-30 wt.% of feldspar as flux component, and 0-25 wt.% of silica sand and/or chamotte, are mixed together and then molded; the resulting molded from is subsequently baked at 1,050-1,250 deg.C with the proportion of the cutlet at 5-45 wt.%, or at 1,160-1,230 deg.C with the proportion of the cutlet at 5-35 wt.%, thus obtaining the objective clay ceramic with a baking contraction of <=2.4% when the saturated water absorption stands at 5 wt.%, <=3.5% when the open porosity (the ratio of open pore volume to external volume) stands at <=12% and the saturated water absorption at 1%, or with extremely low contraction when the open porosity stands at >=19.0%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to ceramic ceramics such as tiles and tableware, and a method for producing the same, and more particularly to a ceramic ceramic having a small firing shrinkage, a high closed porosity and a small water absorption, and a method for producing the same.

[0002]

2. Description of the Related Art It has been known that steatite ceramics made of talc as a main raw material have a small firing shrinkage even when baked to a water absorption of 3% or less. This is because, as described in JP-B-60-48268, column 1, line 19 to column 2, line 1, the particle gap during molding remains as closed pores even after firing. It is considered. Incidentally, the closed porosity is a ratio of the closed pore volume in the outer volume,

[0003]

(Equation 1)

[0004] Here, W1: the dry weight of the sample, W2: the weight of the sample in water after absorbing the reduced pressure, W3: the weight of the sample after absorbing the reduced pressure, and D: the true specific gravity of the sample. In addition,
The reduced pressure water absorption is performed in accordance with the vacuum method of ISO10545-3.

As shown in FIG. 2 of Japanese Patent Publication No. 2-36543, it is known that the closed pore structure of steatite ceramics is such that hollow pores are connected to the tile surface by fine pores. I have.

A method for producing steatite ceramics is disclosed in JP-B-60-48268, JP-B-2-365.
No. 43, etc., but all use talc as a main raw material,
Clay and bentonite are used as molding aids, and feldspar is used as flux. As described above, in steatite ceramics, feldspar is generally used as a flux. In this case, since the calcination temperature of 1100 to 1250 ° C. is a temperature range where feldspar starts melting, the melt viscosity of the flux is still high, and as shown in FIG. There are many.
In order to reduce the water absorption of such a substrate, it is common to increase the amount of flux or raise the firing temperature. However, in this case, there is a problem that the shrinkage rate increases.
In addition, since it is fired near the melting start temperature of feldspar,
Shrinkage and water absorption are likely to change due to subtle differences in furnace temperature, raw material pulverization particle size, and compaction of moldings due to variations in molding pressure, etc., and as a result, variations in dimensions and water absorption increase. There is also a problem.

Japanese Patent Publication No. 61-27347 discloses a production method using glass for steatite ceramics.
35 to 50 parts by weight of talc, 17.5 to 35 parts by weight of pyroxene, 17.5 to 37.5 parts by weight of feldspar or sericite,
A method of mixing, molding and firing 10 parts by weight of bentonite is described. The same publication, column 4, 18 to 23
The line states that cullet such as plate glass and bottle glass may be further added, but there is no description about the specific amount of glass cullet added.

Japanese Patent Application Laid-Open No. 55-113662 describes a method for producing ceramics by mixing, shaping and firing about 50 wt% of glass dust, about 40 wt% of talc, and about 10 wt% of bentonite. This is intended to improve the dimensional accuracy by firing at a low temperature of 600 to 1000 ° C. When the water absorption is 3% or more, the amount of glass melting is small, and enstatite and mullite, which provide the strength of the substrate, are also used. Sufficient strength cannot be obtained because it hardly forms at temperature. In addition, when baking is performed at a water absorption of 3% or less, there is a problem that the melt viscosity is low due to the large amount of glass, and the substrate is deformed during firing. Furthermore, since talc is dehydrated at 900 to 1000 ° C., when fired at this temperature, the amount of glass added is as large as 50%, but the tile surface is covered with molten glass near the maximum temperature, and the dehydrated steam is removed from the tile. You cannot get out of the room and the tile itself swells like a lens. In addition, when firing at 1000 ° C. or lower, there is also a disadvantage that the chemical resistance of a glaze usable in that temperature range generally deteriorates.

[0009]

DISCLOSURE OF THE INVENTION The present invention relates to a method for manufacturing such as having a frost damage resistance, a low shrinkage rate, a low water absorption rate, a high closed porosity, a firing temperature, and filling of a molded article. An object of the present invention is to provide a method for producing a ceramic ceramic which is less affected by variations in conditions.

[0010]

Means for Solving the Problems The method for producing a ceramic ceramic according to the present invention is as follows. Characterized by mixing, shaping and firing.

The present invention has been accomplished by finding that the above object can be achieved by blending an appropriate amount of glass with the talc-clay main raw material.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the composition of the raw materials of the present invention will be described.

In the present invention, as described above, talc 40 to 6
5wt%, clay 5-30wt%, glass swarf 5-45wt
%, Feldspar 0-30 wt%, silica sand and / or chamotte 0-25 wt%.

This talc is a main raw material for forming a steatite base. If the proportion of talc is less than 40% by weight, the packing density at the time of molding becomes low, and as a result, firing shrinkage becomes large. On the other hand, if the talc is 65 wt% or more, the base becomes excessively high in fire resistance, and the firing temperature becomes excessively high. In this case, the firing temperature is set to 1100 to 125
When the temperature is set to 0 ° C., the sintering becomes insufficient, and the water absorption of the ceramics increases. A particularly preferred range of talc is 4
5 to 55 wt%.

Clay functions as a molding aid, and includes Kibushi clay, Frogme clay, bentonite and the like. If the proportion of the clay is less than 5 wt%, the strength of the molded body is low. On the other hand, if the amount of the clay is more than 30% by weight, the melt viscosity becomes low, and the deformation of the base during firing becomes large. The compounding amount of the clay is preferably 7 to 25 wt%, particularly preferably 10 to 20 wt%.

Glass dust has the function of lowering the firing temperature and reducing the water absorption rate of the fired body without increasing the shrinkage, but if it is more than 45 wt%, in the range of 1100 ° C. to 1250 ° C. During firing, the substrate melts and deformation increases. On the other hand, when the amount of
If the amount is less than wt%, the effect of adding glass dust becomes insufficient. A particularly preferred blending amount of the glass dust is 7 to 25 wt%,
In particular, it is 10 to 20 wt%.

As the glass waste, it is desirable that the working point at which the glass melts and becomes liquid is 1050 ° C. or less. In particular, soda-lime glass such as sheet glass waste and bottle glass waste is desirable.

Feldspar is a flux component.
This feldspar is an optional additive component and need not be added.
Feldspar is preferably at most 30 wt%, particularly preferably at most 15 wt%.

Silica sand and chamotte are used as extenders and are optional components. If the ratio of silica sand and chamotte is greater than 25 wt%, the water absorption rate increases, so the total amount of silica sand and chamotte is 25 wt% or less.

With respect to silica sand and chamotte, it is also possible to use glass having a high content of SiO ₂ such as quartz glass as having the same role.

In the present invention, these raw materials are mixed, molded, and fired. The method of mixing and firing is not particularly limited. The firing temperature is 1050 to 1250 ° C, particularly 1160 to 1250C.
1230 ° C. is preferred.

In the method of the present invention, the proportion of glass swarf is 5 to 45 wt%, and the firing temperature is 1050 to 1250 ° C.
, Preferably, the ratio of the glass waste is 5 to 3
By setting the firing temperature to 1160 to 1230 ° C. at 5 wt%, the firing shrinkage is 2.4% when the saturated water absorption is 5%.
Hereinafter, when the closed porosity is 12% or more and the saturated water absorption is 1%.
It is possible to manufacture a ceramic having an extremely low shrinkage of 5% or less and a closed porosity of 19.0% or more. The saturated water absorption is based on the boiling method of ISO 10545-3.

The reason is as follows. One method for increasing the dimensional accuracy of ceramics is to reduce the bulk density by increasing the number of closed pores in the fired body, as described above. As shown in FIG. 2 of Japanese Patent Publication No. 2-36543, it is known that a base using talc has hollow holes and fine pores in the base. The glass used this time has a low melt viscosity at a firing temperature of 1100 ° C. or higher, so that it is easier to fill fine pores than feldspar.
Therefore, as shown in FIG. 1, when feldspar is used,
The internal pores connected to the outside through the fine pores become closed pores when glass is used. As a result, the closed porosity increases and the bulk density decreases, resulting in low shrinkage and increased dimensional accuracy. In addition, enstatite is generated because it is fired at a temperature of 1050 ° C. or more, and mullite is generated when it is fired at a temperature of 1160 ° C. or more, so that sufficient strength is obtained.

[0024]

EXAMPLES Example 1, Comparative Examples 1-4 Talc, bentonite, clay, quartz sand, glass swarf, feldspar,
Rouseki was blended in the proportions shown in Table 1. Here, Comparative Examples 1 and 2 and Comparative Examples 3 and 4 are described in Japanese Patent Publication No. 60-48468 and Japanese Patent Publication No. 61-27347, respectively. This was pulverized by a ball mill for 4 hours, mixed, dried, hydrated, granulated, and press-molded (surface pressure: 30 MPa).
A molded body of 100 × 100 × 5 mm was obtained. This was unbaked in a rapid firing furnace at 1100 ° C. for 30 minutes, and after glazing, quickly fired at 1200 ° C. for 50 minutes. The shrinkage due to the firing was measured to calculate the shrinkage, and the saturated water absorption and closed porosity were measured. Table 1 shows the results.

Example 2, Comparative Example 5 Talc, Kibushi clay, sheet glass scrap, feldspar and silica sand were blended in the proportions shown in Table 2, and ground and unbaked in the same manner as in Example 1, Comparative Examples 1-4. After glazing, 1170, 1190,
Alternatively, it was quickly fired at 1210 ° C. for 50 minutes. The shrinkage and the saturated water absorption due to this firing were measured. Table 2 shows the results. FIG. 2 shows the correlation.

Example 3, Comparative Example 6 Talc, Kibushi clay, glass swarf, feldspar, and silica sand were blended in the proportions shown in Table 3 and pulverized in a ball mill until the average particle diameter (D50) became 12 microns, and dried. After being hydrated and granulated, press-molding (contact pressure 28, 30, 32 MPa), 100 × 10
A molded body of 0 × 5 mm was obtained. This is put in a rapid firing furnace for 110
Perform calcination (unglazed) at 0 ° C for 30 minutes, and after glazing,
Rapid firing was performed at 1200 ° C. for 50 minutes. Table 3 shows the shrinkage rate, boiling water absorption rate, and closed porosity associated with the firing.

Examples 4 to 6 Talc, Kibushi clay, glass swarf, and chamotte were blended in the proportions shown in Table 4, pulverized by a ball mill for 4H, dried, hydrated, granulated, and press-molded (surface pressure: 30 MPa). 100 × 10
A molded body of 0 × 8.5 mm was obtained. After glazing, the saturated water absorption of each sample is approximately 5% and 1% in a rapid firing furnace.
The firing was performed under the following conditions. Table 4 shows the shrinkage, boiling water absorption, and closed porosity associated with the firing.

[0028]

[Table 1]

Example 1 has a higher closed porosity than Comparative Examples 1 to 4. Comparative Examples 1 and 2 have low shrinkage but high saturated water absorption, and consequently low closed porosity. Comparative Examples 3 and 4 and Example 1 have almost the same saturated water absorption, but Example 1 has the lowest shrinkage. This is reflected in the difference in closed porosity.

[0030]

[Table 2]

As is clear from the comparison between Example 2 and Comparative Example 5, the addition of glass dust significantly reduces both the shrinkage and the saturated water absorption. When the firing temperature is 1
It is recognized that the fluctuation range is small even when the temperature is changed between 170 to 1210 ° C. In addition, the closed porosity is higher when glass dust is used at any temperature level.

[0032]

[Table 3]

As is evident from the comparison between Example 3 and Comparative Example 4, when glass is used, the shrinkage ratio and the boiling water absorption ratio with respect to the change in the pressure, that is, the change in filling of the compact, are higher than when feldspar is used. Is small.

[0034]

[Table 4]

As in Examples 4 to 6, the fire resistance is reduced by increasing the amount of glass, and it is possible to lower the saturated water absorption at a lower temperature. From this, it can be seen that a sample having the desired water absorption can be obtained by changing the firing temperature depending on the amount of glass added.

[0036]

As described above, according to the method for producing a ceramic ceramic of the present invention, a low shrinkage rate and a low water absorption rate are obtained.
In addition, it is possible to manufacture a porcelain that is less affected by changes in the firing temperature and the filling of the substrate.

[Brief description of the drawings]

FIG. 1 is a view showing the concept of a green body after firing when feldspar and glass are used as a flux.

FIG. 2 is a graph showing measurement results of Example 2 and Comparative Example 5.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Kenji Okamoto 5-1-1 Koiehonmachi, Tokoname-shi, Aichi Inax Inc. (72) Inventor Katsuhiko Akita 12-4 Futabacho, Itabashi-ku, Tokyo

Claims (4)

[Claims] 1. A raw material comprising 40 to 65 wt% of talc, 5 to 30 wt% of clay, 5 to 45 wt% of glass dust, 0 to 30 wt% of feldspar and 0 to 25 wt% of silica sand and / or chamotte are mixed, molded and fired. Method of producing ceramic ceramics. 2. The method according to claim 1, wherein the firing temperature is 1050.
A method for producing a ceramic ceramic, wherein the temperature is 1250C. 3. The method according to claim 2, wherein after calcining, the amount is 1050 to 1050.
A method for producing porcelain ceramics, characterized by firing at 1250 ° C. 4. The method for producing a ceramic ceramic according to claim 1, wherein the proportion of glass waste is 5 to 35 wt% and the firing temperature is 1160 to 1230 ° C.