JP2000319061A - Ceramic and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent of the penetration of water with time due to hydration swelling or the problems of damage from coldness injury or contamination by forming the center part of the base of a ceramic from a water absorptive ceramic base and decreasing the water absorption of a part of the surface of the base, where a glazed layer is not formed, than that of the center part. SOLUTION: The glazed layer 2 is formed on the necessary part of the base 1 of the ceramic, the center part 3 of the base 1 is formed from the ceramic base having water absorptivity and the surface part 4 is formed from the ceramic base having smaller water absorptivity than that of the center part 3. That is, the composition of the center part 3 is controlled to 45-70 wt.% SiO2, 25-50 wt.% Al2O3, <=2 wt.% total of an alkali metal oxide and <=6 wt.% total of an alkali metal oxide and an alkaline earth metal oxide. The composition of the surface part 4 is controlled to 45-70 wt.% SiO2, 25-50 wt.% Al203, >=5 wt.% total of the alkali metal oxide and >=6 wt.% total of the alkali metal oxide and the alkaline earth metal oxide.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to ceramics represented by sanitary ware, tiles, tableware and the like, and a method for producing the same.

[0002]

2. Description of the Related Art In general, a ceramic product has a glaze layer formed only on a necessary portion of a ceramic substrate, for example, on a floor installation portion of a toilet bowl, a tile back surface, a circular leg portion of tableware. The base is exposed without a glaze layer.

[0003] Therefore, when the base material is formed of pottery, water generally permeates the pottery, so that water penetrates into the base material through the exposed portion of the base material, causing problems such as secular penetration due to hydration expansion and frost damage in cold regions. May occur. Therefore, conventionally, by firing and melting, a glass phase is generated,
The glass phase fills the gaps between the particles in the substrate, densifies the entire substrate, and has been devised to eliminate water absorption.

[0004]

However, going through such a sintering process has caused large firing shrinkage and deformation of the substrate, which has been a cause of deteriorating the accuracy of product dimensions. In other words, in order to obtain the target product dimensions, the so-called slicing was performed, in which the raw dimensional shape was determined in consideration of the firing shrinkage amount and the deformation accompanying the shrinkage. The variation was large, and in some cases, a repair work such as grinding was required. The present invention has been made in view of the above circumstances, and has as its object to eliminate the problem of hygiene such as aging, frost damage, and contamination due to hydration expansion, and without any modification work during manufacturing. An object of the present invention is to make it possible to provide a ceramic with good product dimensional accuracy.

[0005]

According to the present invention, in order to solve the above-mentioned problems, there is provided a ceramic comprising a base and a glaze layer formed on a necessary portion on the base, wherein a central portion of the base is made of a water-absorbing material. Provided is a porcelain made of a certain porcelain base material, wherein at least a portion of the surface portion of the base material where the glaze layer is not formed has a smaller water absorption than a central portion of the base material. By doing so, the central part of the base is a water-absorbing porcelain base, so it can be produced with as little shrinkage and deformation as possible during firing, and at least the glaze layer is formed on the surface of the base. Since the water absorption is smaller in the unexposed part than in the central part of the base, the water absorption in the exposed part of the base is suppressed, and problems such as aging expansion due to hydration expansion and freezing damage in cold regions are unlikely to occur.

In a preferred embodiment of the present invention, the ceramic is a ceramic comprising a base and a glaze layer formed on a necessary portion on the base, wherein a central portion of the base has an ink penetration of more than 3 mm and At least the portion where the glaze layer is not formed on the surface has an ink penetration of 3 m.
m or less. By doing so, the central part of the base is a porous and water-absorbing ceramic base material with an ink penetration of 3 mm or more, so that shrinkage and deformation during firing can be suppressed as much as possible, and the surface of the base can be manufactured. At least in the portion where the glaze layer is not formed, since the ink penetration is 3 mm or less, water absorption from the exposed portion of the base material is suppressed, and problems such as aging due to hydration expansion and frost damage in cold regions are reduced. It is hard to occur.

[0007] In a preferred embodiment of the present invention, the central portion of the base material has a composition of 45 to 70% by weight of SiO _{2 and} 25 to 50% by weight of Al ₂ O ₃ , and other compositional components. At least one alkali metal oxide selected from the group consisting of Na ₂ O, K ₂ O and Li ₂ O and / or CaO, Mg
At least one alkali metal oxide selected from the group consisting of Na ₂ O, K ₂ O, and Li ₂ O, including at least one alkaline earth metal oxide selected from the group consisting of O, BaO, and BeO The total amount of the substances is 2% by weight or less, and Na ₂ O, K ₂ O, Li ₂ O
The total amount of at least one alkali metal oxide selected from the group consisting of and at least one alkaline earth metal oxide selected from the group consisting of CaO, MgO, BaO, and BeO is 6% by weight or less; The surface portion of the substrate has a composition of main components of SiO ₂ : 45 to 70% by weight and Al ₂ O ₃ : 25 to 50% by weight, and Na ₂ O, K ₂ O, Li ₂ At least one alkali metal oxide selected from the group consisting of O and / or at least one alkaline earth metal oxide selected from the group consisting of CaO, MgO, BaO, and BeO;
The total amount of at least one alkali metal oxide selected from the group consisting of ₂ O, K ₂ O, and Li ₂ O is 5% by weight or more, and the group consisting of Na ₂ O, K ₂ O, and Li ₂ O The total amount of at least one alkali metal oxide selected from the group consisting of CaO, MgO, BaO and BeO is at least 6% by weight. Regarding the composition of the central portion, the total amount of at least one alkali metal oxide selected from the group consisting of Na ₂ O, K ₂ O, and Li ₂ O is 2% by weight or less, and Na ₂ O, K ₂ O, Li ₂ O, at least one alkali metal oxide selected from the group consisting of CaO, Mg
By making the total amount of at least one kind of alkaline earth metal oxide selected from the group consisting of O, BaO, and BeO not more than 6% by weight, the generation of a glass phase is suppressed, and firing shrinkage and accompanying Deformation is reduced. In addition, regarding the composition of the surface portion, the total amount of at least one alkali metal oxide selected from the group consisting of Na ₂ O, K ₂ O, and Li ₂ O is 5% by weight or more, and Na ₂ O, K ₂ At least one alkali metal oxide selected from the group consisting of O, Li ₂ O and CaO, MgO, BaO, B
By setting the total amount of at least one kind of alkaline earth metal oxide selected from the group consisting of eO to be more than 6% by weight, the formation of a glass phase is promoted at the surface portion, and the surface portion is densified and water absorption is suppressed. Is done. Therefore, problems such as secular penetration due to hydration expansion and freezing damage in cold regions are less likely to occur.

[0008] In a preferred embodiment of the present invention, the central portion of the base further contains at least one mineral selected from the group consisting of quartz, cristobalite, mullite, and corundum as crystals. By doing so, the strength of the central portion of the base is improved.

[0009] In a preferred embodiment of the present invention, the content of alkali metal oxide in the components constituting the central portion of the substrate is such that the weight percentage of Na ₂ O is greater than the weight percentage of K ₂ O. . By doing so, when vitrification of the surface proceeds, Na has a higher effect as a sintering aid than K, and as a result, the effect of densification of the surface increases.

In a preferred embodiment of the present invention, the Na ₂ O content of the components constituting the central portion of the substrate is 1% by weight or more. By doing so, vitrification of the surface proceeds further, and the effect of densification of the surface portion is enhanced.

[0011] In a preferred embodiment of the present invention, the same base and glaze as the above-mentioned porcelain are used, and φ14 × 130 m
m, a bending strength calculated when a three-point bending test is performed by an autograph using the test piece under conditions of a span of 100 mm and a crosshead speed of 2.5 mm / min is 30 MPa or more, and Using the same base and glaze as the ceramic, width 25 mm,
Prepare a test piece with a thickness of 5 mm and a length of 230 mm,
The test piece is supported at two points with a span of 200 m.
Temperature to 000 ° C in 4 hours, and then to 1200 ° C for 2 hours.
After raising the temperature for 1 hour and holding at 1200 ° C. for 1 hour, the amount of deflection of the test piece when naturally cooled to room temperature is 5 mm.
Make sure that: By doing so, it is possible to obtain a product having strength that can be used as a normal product, small firing deformation, and stable dimensional accuracy.

In a preferred embodiment of the present invention, when a test piece is manufactured using the same base material and glaze as the above-mentioned porcelain, the linear thermal expansion coefficient of the test piece in the longitudinal direction is 90 × 10 ^−7. / ° C or lower. By doing so, the matching with the glaze generally used for ceramic products is good, and the occurrence of defects on the glaze surface such as glaze skipping and penetration is less likely to occur. In addition, the substrate is prevented from being cut during the cooling process in the firing step of the substrate itself, and the thermal shock resistance is further improved.

[0013] In one manufacturing method of the porcelain of the present invention,
SiO ₂ , a base material preparation step of preparing a base material by adjusting the particle size of the ceramic raw material containing Al ₂ O ₃ as a main component, and water and an alkali metal such as Na, K, Li, Ca, M
g, an alkaline earth metal such as Ba, a step of adding at least one water-soluble compound containing any of boron, and a molding step of forming a molding base, and drying the molding base. A drying step, a glaze step of applying a glaze to the molding base, and a firing step are performed. Na,
Add at least one compound from water-soluble compounds containing any of alkali metals such as K and Li, alkaline earth metals such as Ca, Mg and Ba, and boron, and then dry after molding. Thereby, in the drying step, the alkali metal oxide component or the alkaline earth metal oxide component is transferred to the surface at the same time as the moisture, and the alkali metal oxide component or the alkaline earth metal oxide component on the surface is more than the central part of the base. In this case, vitrification of only the surface portion proceeds easily during firing. As a result, the surface portion can be densified, the water absorption of the surface portion can be suppressed, and the firing shrinkage of the central portion of the base can be reduced.

In a preferred aspect of the present invention, in the drying step, in order to move more alkali metal or alkaline earth metal to the predetermined surface portion, a process of increasing a water evaporation rate from the predetermined surface portion is performed. I do. By performing the process of increasing the evaporation rate of water from the predetermined surface portion, more alkali metal or alkaline earth metal is moved to the predetermined surface portion, the densification of the predetermined surface portion is promoted, and the water absorption of the surface portion is suppressed. Is done.

In a preferred aspect of the present invention, the porcelain is a toilet, and the predetermined surface portion is inside a trap or a rim. By doing so, even within the trap or rim, which is difficult to dry, the water evaporation rate is increased, and a sufficient amount of alkali metal or alkaline earth metal can move to the surface. Therefore, densification of the surface portion is promoted, vitrification of the surface portion proceeds, and water absorption is suppressed.

In a preferred embodiment of the present invention, the porcelain is a basin, and the porcelain is inside the overflow. By doing so, even in the overflow that is difficult to dry, the water evaporation rate is increased, and a sufficient amount of alkali metal or alkaline earth metal can move to the surface. Therefore, densification of the surface portion is promoted, vitrification of the surface portion proceeds, and water absorption is suppressed.

[0017] In a preferred embodiment of the present invention, the treatment is performed by using hot air or alkaline air to transfer more alkali metal or alkaline earth metal to the surface to which the alkali metal or alkaline earth metal is to be transferred. The process is to flow cold air. By doing so, it is possible to easily treat the above-mentioned hard-to-dry portions.

In a preferred embodiment of the present invention, the treatment is performed by using an infrared lamp to transfer more alkali metal or alkaline earth metal to the surface where the alkali metal or alkaline earth metal is to be transferred. The process is to irradiate heat from such a radiant heat source. By doing so, it is possible to easily treat the above-mentioned hard-to-dry portions.

In a preferred embodiment of the present invention, the treatment is performed by microwave heating in order to move the alkali metal or the alkaline earth metal more to the surface to which the alkali metal or the alkaline earth metal is to be moved. To promote drying. By doing so, it is possible to easily treat the above-mentioned hard-to-dry portions.

In a preferred embodiment of the present invention, the water-soluble compound is any of carbonate, acetate, sulfate and citrate. When a water-soluble alkali metal salt is added to the raw material slurry, the raw material slurry is agglomerated, which may make casting and the like difficult, but as the added alkali metal salt, carbonate, sulfate, acetate, The use of citrate is preferred because the raw material slurry is less likely to aggregate.

In another method for producing the ceramics of the present invention, there is provided a base material preparation step of preparing a base material by adjusting the particle size of a ceramic raw material containing SiO ₂ and Al ₂ O ₃ as main components; After performing a step of forming a molding base by molding using, and optionally a drying step,
Alkali metal such as Na, K, Li, C on the surface of the green body
a, Mg, an alkaline earth metal such as Ba, an aqueous solution containing at least one water-soluble compound containing any of boron, an application step of applying to the surface an aqueous solution, a drying step, and applying a glaze to the molded substrate The applied glaze process and firing process are performed. As described above, in the post-forming step, at least one of water-soluble compounds containing any of alkali metals such as Na, K, and Li, alkaline earth metals such as Ca, Mg, and Ba, and boron on the surface of the forming substrate. Is applied to the surface, the alkali metal oxide component or the alkaline earth metal oxide component on the surface becomes larger than that in the central portion of the substrate, and vitrification of only the surface during firing is facilitated. As a result, the surface portion can be densified, the water absorption of the surface portion can be suppressed, and the firing shrinkage of the central portion of the base can be reduced.

In a preferred aspect of the present invention, the application method in the application step is a spray method using ultrasonic waves. By doing so, it is possible to easily apply the liquid to a portion that is difficult to apply, such as the inside of the trap or rim of the toilet or the inside of the overflow of the basin.

[0023] In a preferred embodiment of the present invention, the raw material is a clay mineral comprising at least one selected from kaolinite, dickite, halloysite, sericite and pyrophyllite as essential components of the main mineral, and quartz. Including, if necessary, mullite as an optional ingredient,
It contains at least one kind of mineral selected from corundum and diaspore, and further contains, as necessary, an alkali metal-containing mineral such as feldspar and an alkaline earth metal-containing mineral such as dolomite. By doing so, while maintaining the formability of the clay mineral, the base matrix is strengthened by melting the quartz in the firing step, and further, as an optional component, mullite, corundum, diaspore mineral, or containing alkaline earth The strength of the central portion of the base can be improved by the minerals and the alkaline earth metal-containing minerals.

In a preferred embodiment of the present invention, the raw material has an average particle diameter of 1 to 20 μm, preferably 5 to 10 μm, measured by a laser diffraction type particle size analyzer. If the average particle diameter is 1 μm or less, the state of aggregation of the slurry becomes severe, making peptization difficult, and causing problems in moldability. On the other hand, when the average particle diameter is 20 μm or more, the melt sintering of the base material becomes insufficient, and sufficient strength cannot be obtained.

In a preferred embodiment of the present invention, the molding method in the molding step is a slip casting. As a result, alkali metal salts or alkaline earth metal salts, which are indispensable for densification of the surface, can be easily incorporated into the slurry, and large complex shaped products represented by sanitary ware can be dimensioned. It can be molded accurately and easily.

In a preferred embodiment of the present invention, the sintering temperature in the sintering step is 1100 to 1300 ° C. By firing at a high firing temperature of 1100 ° C. to 1300 ° C., it is possible to have a practically problematic strength of 30 MPa or more in bending strength without extremely lowering the substrate strength. If the firing temperature is lower than 1100 ° C., the melting and mineralization of the substrate become insufficient, and the desired strength cannot be obtained. On the other hand, if the temperature is higher than 1300 ° C., the fusion sintering proceeds too much, so that it is not possible to obtain the desired firing shrinkage and deformation.

In a preferred aspect of the present invention, at least the longitudinal shrinkage amount in the firing step is 7% or less. By doing so, the variation in the amount of shrinkage in firing during the firing step is reduced, and a product with stable dimensional accuracy can be obtained.

In a preferred embodiment of the present invention, a test piece molded body having a width of 30, a thickness of 15 and a length of 260 mm is produced in the molding step, and the test piece molded body is supported at a span of 200 mm to be the same as a ceramic. The deflection amount when fired under the above firing conditions is 20 mm or less in terms of a fired body thickness of 10 mm. By doing so, the amount of sintering deformation during the sintering step is reduced, and a product with stable dimensional accuracy can be obtained.

[0029]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. In the present invention, the substrate 1
The glaze layer 2 is formed on the required portion on the upper side. The base 1 has a different structure at a central portion 3 and a surface portion 4. The central portion 3 is made of a water-absorbing ceramic body, and the surface portion 4 has a smaller water absorption than the central portion 3.
The composition of the central portion 3 is such that the composition of the main component is SiO ₂ 45-7.
0 wt%, Al ₂ O _3: a 25 to 50% by weight, as the other constituents of the _{composition, Na 2 O, K 2 O} , at least one alkali metal oxide selected from the group consisting of Li ₂ O and // Ca
At least one selected from the group consisting of O, MgO, BaO, BeO
Contains the kind of alkaline earth metal oxide, quartz as a crystal,
Contains at least one mineral selected from the group consisting of cristobalite, mullite, and corundum; Na ₂ O, K ₂
The total amount of at least one alkali metal oxide selected from the group consisting of O and Li ₂ O is 2% by weight or less;
_At least one alkali metal oxide selected from the group consisting of ₂ O, K ₂ O, and Li ₂ O and at least one alkaline earth metal oxide selected from the group consisting of CaO, MgO, BaO, and BeO Is not more than 6% by weight. Also, the weight percentage of Na ₂ O is K ₂
O is contained in an amount of more than 1% by weight and 1% by weight or more based on all the oxides constituting the substrate. The composition of the surface portion 4 is such that the composition of the main component is SiO ₂ : 45 to 70% by weight,
₂ O ₃ : 25 to 50% by weight, and at least one alkali metal oxide selected from the group consisting of Na ₂ O, K ₂ O, and Li ₂ O and / or CaO, MgO , Ba
O, containing at least one kind of alkaline earth metal oxide selected from the group consisting of BeO, Na ₂ O, K ₂ O, at least one kind of alkali metal oxide selected from the group consisting of Li ₂ O A total amount of 5% by weight or more, and at least one alkali metal oxide selected from the group consisting of Na ₂ O, K ₂ O, and Li ₂ O and a group consisting of CaO, MgO, BaO, and BeO; The total amount of the at least one alkaline earth metal oxide is more than 6% by weight.

In the ceramic of FIG. 1, a test piece of φ14 × 130 mm was prepared using the same base and glaze of the same composition and composition, and the test piece was used to autograph the span 100 mm and the crosshead speed 2.5 m.
The bending strength calculated when performing a three-point bending test under the condition of m / min is 30 MPa or more. Further, a test piece having a width of 25 mm, a thickness of 5 mm, and a length of 230 mm was prepared using a base and a glaze having the same configuration and composition as those of the ceramics, and the test piece was supported at two points with a span of 200 m.
The temperature was raised to 00 ° C. in 4 hours, further raised to 1200 ° C. in 2 hours, held at 1200 ° C. for 1 hour, and then naturally cooled to room temperature, and the amount of deflection of the test piece was 5 mm or less. Furthermore, when a test piece is manufactured using a base and a glaze having the same configuration and composition as the ceramic, the linear thermal expansion coefficient of the test piece in the longitudinal direction is 90 × 10 ^−7.
/ ° C or less.

The porcelain is penetrated by aging due to hydration,
There is no problem in hygiene such as frost damage and contamination, and the accuracy of the product dimensions is good without any modification work during manufacturing.
Therefore, it can be widely used for a basin, a urinal, a toilet, a baby bath, a toilet bowl, a hand basin, a toilet tank, and the like.

The ceramic of FIG. 1 can be manufactured, for example, by the following two methods. (1) a base material preparation step of adjusting the particle size of a ceramic raw material containing SiO ₂ and Al ₂ O ₃ as main components and producing a base material having an average particle diameter of 1 to 20 μm measured by a laser diffraction type particle sizer; And at least one water-soluble compound containing water and an alkali metal such as Na, K and Li, an alkaline earth metal such as Ca, Mg and Ba, or boron as the raw material.
After the steps of seeding are sequentially performed, a forming step of forming a forming base by a method such as slurry casting, a drying step of drying the forming base, a glazing step of applying a glaze to the forming base, 1100 to 1300 The firing step is performed at a temperature of ° C. (2) a base material preparation step of adjusting the particle size of the ceramic raw material containing SiO ₂ and Al ₂ O ₃ as main components and producing a base material having an average particle diameter of 1 to 20 μm measured by a laser diffraction type particle size measuring device; Forming a molded body by molding using the raw material by a method such as slip casting.
After sequentially performing a drying step as necessary, the surface of the green body, Na, K, alkali metals such as Li, Ca, Mg, alkaline earth metals such as Ba, water-soluble containing any of boron. A coating step of applying an aqueous solution containing at least one compound to the surface, a drying step, a glaze step of applying a glaze to the molding base, and a firing step at a temperature of 1100 to 1300 ° C are performed.

In the method (1), when the water-soluble compound is any of carbonate, acetate, sulfate and citrate, the slurry is less likely to coagulate.
Any water-soluble alkali metal salt such as sulfate, nitrate, hydroxide and metal complex can be used. In the drying step, it is preferable to perform a process of increasing the evaporation rate of water from the surface portion 4 in order to move more alkali metal or alkaline earth metal to the surface portion 4. As a specific method therefor, a method of flowing hot or cold air, a method of irradiating heat with a radiant heat source such as an infrared lamp, a method of applying microwave heating to promote drying, and the like can be suitably used.

In the method (2), a commonly used method such as dipping, brushing, roller coating, ironing, spraying, or spraying can be used. On the other hand, the ultrasonic spray method is preferable.

When ceramics are manufactured by the methods (1) and (2), in the firing step, at least the longitudinal shrinkage is 7%.
Width 30, thickness 15, length 260 produced under the same conditions as for the porcelain up to the step before drying
When a test piece molded body having a thickness of 2 mm is supported at a span of 200 mm and fired under the same firing conditions as that of the porcelain, the amount of deflection becomes equal to or less than 20 mm in terms of a fired body thickness of 10 mm.

Next, some of the terms used in this specification will be described in more detail. The surface portion refers to a generally used surface chemical composition analyzer (for example, a fluorescent X-ray analyzer 327 manufactured by Rigaku Denki Co., Ltd.) after molding, drying and firing the substrate.
0) indicates a range that can be analyzed from the surface, and is usually several tens μm in the thickness direction from the surface. The central part of the green body refers to a part which is obtained by cutting the sintered body in the thickness direction and substantially hitting the center between the front surface and the back surface.

The ceramic raw material means both a raw material used as a normal raw material for a solubilized material and a raw material used as a refractory raw material. Here, the solubilized base material is, for example, pottery stone, feldspar, quartzite, mica, kaolin, frog eye clay, Kibushi clay, dolomite, and the like, and the refractory raw material is, for example, limestone, ban shale, Chamotte, limestone clay, refractory clay, flint clay, bauxite, magnesia clinker, etc. It is desirable to use the raw material for the solute and the refractory raw material together. It is better to use refractory raw materials such as raw materials with low contents of alkali metal oxides and alkaline earth metal oxides such as rosacea and chamotte raw materials than in the case where the green body is prepared using only the composition of the solubilized raw materials. This is because it is easy to reduce metal oxides and alkaline earth metal oxides.

The ultrasonic atomizer is a generally commercially available ultrasonic humidifier, ultrasonic inhaler, or the like, which is capable of converting an aqueous solution into a mist containing an alkali metal or an alkaline earth metal. is important. Because it is a mist,
It can penetrate into a tube-shaped thing such as a trap or a complicated shape such as inside a rim.

[0039]

FIG. 2 shows the composition of the base material, the chemical composition, and the crystalline minerals of the example of the present invention and the comparative example. The base material was prepared by weighing predetermined raw materials, wet-pulverizing 35 parts of water and an appropriate amount of sodium silicate as a peptizer in a pot mill to adjust the average particle diameter to 6 μm. Here, as the alkali metal salt contributing to surface densification, an alkali metal citrate is selected because the cohesiveness of the raw material slurry is the lowest,
Lithium citrate, sodium citrate and potassium citrate were used. The method of adding the alkali metal salt may be any of a method of adding the alkali metal salt simultaneously with the raw material and a method of adjusting the particle size of only the raw material and then adding the alkali metal salt. The alkali metal salt to be added is not limited to the above, and may be any other water-soluble alkali metal salt such as carbonate, sulfate, acetate, nitrate, hydroxide, and metal complex. It is possible. Next, the raw material slurry was poured into a gypsum mold capable of being formed into a predetermined shape of a sample for measuring physical properties, and was molded and removed from the mold to form a test piece. Test piece is 40 ° C
After drying for 24 hours in an electric furnace,
The temperature was raised to 200 ° C. in 2 hours, held at 1200 ° C. for 1 hour, and then calcined by a heat curve of natural cooling. Here, in the examples, since the sample is based, a steady drying at 40 ° C. is sufficient for all effects. However, for a portion that is difficult to dry, as described in claims 9 to 12, it is necessary to deposit a large amount of alkali metal or alkaline earth metal on the surface on which the alkali metal salt or alkaline earth metal salt is to be deposited. , Cold air, hot air, infrared,
It is preferable to use a microwave or the like to enhance the rate of water evaporation from the surface.

Here, as the molding step, the slurry casting is described in the embodiment, but any other molding method that contains water at the time of molding, such as extrusion molding, lathe molding, and wet press molding, can be applied. It is. Further, in a dry molding method such as powder press molding, an alkali metal salt cannot be added, and thus the production method in which an alkali metal salt is added cannot be applied. It is possible to apply a production method of applying an alkali metal salt.

The bending strength of the substrate was determined by using a test piece of φ14 × 130 mm and an autograph manufactured by Shimadzu for a span of 1 unit.
It is a value measured by a three-point bending method under the conditions of 00 mm and a crosshead speed of 2.5 mm / min.

The firing deformation amounts were 30 for width, 15 for thickness, and 2 for length.
A value obtained by supporting a 60 mm test piece (unfired base) with a span of 200 mm at the time of firing and measuring the deflection amount after firing and the thickness of the test piece. Since the amount of deflection at this time is inversely proportional to the square of the thickness of the test piece after firing, the amount of deflection converted when the thickness is 10 mm by the following equation is defined as the amount of deformation. Firing deformation amount = amount of deflection measurements × (thickness of test piece after baking) ^{2/10 2}

The amount of deformation upon reheating was 25 mm in width and 5 mm in thickness.
A test piece (fired material) having a length of 230 mm and a length of 230 mm was supported at two points with a span of 200 m, and the temperature was raised to 1000 ° C. in 4 hours, and further raised to 1200 ° C. in 2 hours.
After holding at 0 ° C. for 1 hour, the amount of deflection of the test piece when naturally cooled to room temperature is defined as the amount of deformation upon reheating. However, when the thickness of the test piece is not 5 mm, since the amount of deflection is inversely proportional to the thickness of the test piece, the corrected value is used as the deformation amount at the time of reheating. The correction method is to measure the amount of deformation at the time of reheating with two types of test pieces having different thicknesses, calculate n by the following equation, and further obtain the amount of deformation at the time of reheating when the thickness of the test piece is 5 mm. . Deformation amount 2 = Deformation amount 1 x (Thickness 1 / Thickness 2) ⁿ Deformation amount 1: Deformation amount at the time of reheating with test piece of thickness 1 Deformation amount 2: Deformation amount at the time of reheating with test piece of thickness 2 n: constant for correction

As the ink permeability other than the surface portion, a base fracture surface is used instead. For the measurement method, please refer to JI
Implemented in accordance with SA5207, width 30 and thickness 1
5. Break the test piece of 130 mm in length, immerse the fracture surface in a red ink solution (1% concentration of eosin Y solution) for 1 hour or more, wipe off the ink, and determine the maximum penetration size that has permeated into the substrate. It is a measured value.

The ink permeability of the surface portion was 30 for width and 1 for thickness.
5. After filling with non-densified parts such as the back and cross-section of a 130mm long test piece with paraffin or resin so that the red ink does not penetrate, a sufficient amount of red ink to immerse the surface After immersing in a solution (1% eosin Y solution) for 1 hour or more and wiping the ink,
This is a value obtained by measuring the maximum permeation dimension of a sample that has been broken and has penetrated into the substrate.

FIG. 3 shows the physical properties and chemical analysis values of the example and the comparative example. Comparative Example 1 has a general composition of the melt base material, and since the sintering has completely progressed, the ink permeability is 0.1 mm for both the fracture surface and the surface portion. However, it can be seen that firing shrinkage and deformation show the largest values. Comparative Example 2 is a composition obtained by replacing feldspar and dolomite containing a large amount of sintering aid components with kaolin from Comparative Example 1. The amount of the alkali metal oxide is 2% by weight or more, the firing shrinkage and deformation are still large, and the ink permeability is 8.0 mm, and water absorption from the surface cannot be prevented at all. Comparative Example 3 is a case where a refractory raw material such as chamotte is used in combination, and is a preparation in which the amount of alkali metal oxide and the amount of alkaline earth metal oxide of the base material itself are reduced as much as possible. In this case, the firing shrinkage is 3.9%, and the deformation is 4.
3 mm, which is quite small. However, since no alkali metal salt was added, the content of the alkali metal oxide on the surface was not particularly high, and the surface was not densified.

Example 1 is obtained by adding 0.4% in total of an alkali metal salt to Comparative Example 2. In this base composition,
The content of alkali metal oxide on the surface is as high as 5.2%, and as a result, the surface can be densified and the ink penetration is 0.1 mm. However, the amount of the alkali metal oxide in the substrate itself was 2% by weight or more, and the firing shrinkage and deformation amount were slightly higher. Example 2 is obtained by adding 0.3% in total of an alkali metal salt to Comparative Example 3. The alkali metal oxide content at the surface is correspondingly higher. However, since it is about 3.8%, the water absorption from the surface is considerably smaller than that of Comparative Example 3, but the ink permeability is 3.5 mm, which is slightly higher.

In Example 3, the alkali metal salt was added to Comparative Example 3 in a total amount of 0.6%. Firing shrinkage 4.4
% And the amount of deformation is very small at 4.4 mm, but the ink penetration on the surface is 0.1 mm. This is a result of the vitrification of the surface part progressing because the alkali metal oxide content of the surface part was as high as 7.2%. In Example 4, the addition ratio of the alkali metal salt was changed to change the total amount to 0.4%. Even with this addition amount, the alkali metal oxide content on the surface is 6.8%.
, And a good result can be obtained with an ink penetration of 0.2 mm. Example 5 is different from Example 2 in that the Na ₂ O component in the alkali metal oxide base component was larger than the K ₂ O component. Although the overall firing shrinkage is hardly changed, the surface densification is improved and the ink penetration is 2.0 mm. Further, in Example 6, the Na ₂ O component was further increased, but the result was even better with the ink penetration of 0.5 mm. As described above, the effect of surface densification can be improved by selecting an alkali metal oxide component as a sintering aid among components constituting the base.

In Example 7, the slurry of the composition of Comparative Example 3 was poured into a gypsum mold, and after draining, a 20% aqueous solution of sodium citrate was brush-coated on the surface of the sample, followed by drying and firing. In Example 8, a sample was prepared by the same molding method as in Example 7, and a sample was prepared in a 20% aqueous potassium citrate solution.
Dipped for a minute. In Example 9, a sample was prepared by the same molding method as in Example 7, and 20% sodium citrate was applied to the surface of the sample by ultrasonic spraying.
Sprayed for 0 minutes. The alkali metal content in the surface portion was 5.7%, 6.8%, and 6.5%, respectively, and the ink penetration was 0.1 mm in all cases, and good results were obtained. Further, other physical property values such as the firing shrinkage, the deformation amount, and the bending strength are values that are not much different from those of Comparative Example 3. The alkali metal salt aqueous solutions shown in Examples 7 to 9 are not limited to sodium citrate aqueous solution and potassium citrate aqueous solution, but any alkali metal salt such as sulfate, acetate, hydroxide solution, complex solution and the like. A similar effect is obtained even with an aqueous solution. The method of applying an alkali metal salt to the surface is similar to the method described above, but other methods such as spray coating, spray coating, iron coating, and roller coating can also provide similar effects.

[0050]

Industrial Applicability According to the present invention, there is no problem in hygiene such as aging, frost damage and contamination due to hydration swelling, and the porcelain with good accuracy of product dimensions without any modification work during manufacturing. Can be provided.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a general stool type toilet according to an embodiment of the present invention. (A) Cross-sectional view in the front-rear direction of a stool toilet (b) Enlarged view of rim cross-section

FIG. 2 shows a base composition, a chemical composition, and a crystalline mineral of Examples and Comparative Examples of the present invention.

FIG. 3 shows physical properties and chemical analysis values of Examples and Comparative Examples shown in FIG.

[Explanation of symbols]

 1: Base part 2: Glaze layer 3: Base part 4: Base surface part

Claims (29)

[Claims] 1. A ceramic comprising a base material and a glaze layer formed on a necessary portion on the base material, wherein a central portion of the base material is made of a water-absorbing ceramic base material. At least in a portion where the glaze layer is not formed, the water absorption is smaller than a central portion of the base. 2. A ceramic comprising a base material and a glaze layer formed on a necessary portion on the base material, wherein a central portion of the base material has an ink penetration of more than 3 mm and at least a surface portion of the base material. Ceramics characterized in that the ink penetrability is 3 mm or less in the portion where the glaze layer is not formed. 3. The central part of the base material has a main component composition of 45 to 70% by weight of SiO _{2 and} 25 to 50% by weight of Al ₂ O ₃ , and Na ₂ O, K ₂ O, at least one alkali metal oxide selected from the group consisting of Li ₂ O and / or at least one alkaline earth metal oxide selected from the group consisting of CaO, MgO, BaO, BeO Including Na
A total amount of at least one alkali metal oxide selected from the group consisting of ₂ O, K ₂ O, and Li ₂ O is 2% by weight or less, and a group consisting of Na ₂ O, K ₂ O, and Li ₂ O; The total amount of at least one alkali metal oxide selected from the group consisting of CaO, MgO, BaO and BeO is at least 6% by weight; The surface portion has a composition of the main component of SiO ₂ : 45 to 70% by weight, Al
₂ O ₃ : 25 to 50% by weight and as other composition components,
At least one selected from the group consisting of Na ₂ O, K ₂ O, and Li ₂ O
Kinds of alkali metal oxides and / or CaO, MgO, BaO, BeO
At least one alkaline earth metal oxide selected from the group consisting of Na ₂ O, K ₂ O, and Li ₂ O, wherein the total amount of at least one alkali metal oxide selected from the group consisting of
At least one alkali metal oxide selected from the group consisting of Na ₂ O, K ₂ O and Li ₂ O
At least one selected from the group consisting of O, MgO, BaO, BeO
3. A ceramic according to claim 1, wherein the total amount of the alkaline earth metal oxides is more than 6% by weight. 4. The material according to claim 3, wherein the central portion of the base further contains at least one mineral selected from the group consisting of quartz, cristobalite, mullite, and corundum as crystals. China. 5. The weight percentage of Na ₂ O is more than the weight percentage of K ₂ O in the content of the alkali metal oxide among the components constituting the central portion of the base. The porcelain according to 4. 6. The porcelain according to claim 3, wherein the Na ₂ O content of the component constituting the central portion of the base is 1% by weight or more. 7. A test piece of φ14 × 130 mm is prepared using the same material and glaze as the ceramic, and the test piece is used to autograph a span of 100 mm.
mm, the bending strength calculated when performing a three-point bending test under the conditions of a crosshead speed of 2.5 mm / min is 30MP.
a, a test piece having a width of 25 mm, a thickness of 5 mm, and a length of 230 mm was prepared using the same base material and glaze as the ceramic, and the test piece was subjected to a span 200
supported at two points m, the temperature was raised to 1000 ° C in 4 hours, further raised to 1200 ° C in 2 hours, held at 1200 ° C for 1 hour, and then cooled naturally to room temperature. The ceramics according to claim 3, wherein is not more than 5 mm. 8. When a test piece is manufactured using the same base and glaze as the porcelain, the linear thermal expansion coefficient of the test piece in the longitudinal direction is 90 × 10 ⁻⁷ / ° C. or less. The porcelain according to claim 7, wherein: 9. The porcelain according to claim 1, wherein the porcelain is any one of a basin, a urinal, a toilet, a baby bath, a toilet bowl, a hand basin, and a toilet tank. 10. A method for producing the ceramics according to claim 1.
Method, SiO_Two, Al _TwoO_ThreeOf ceramic raw material mainly composed of
Base preparation that produces a base material by adjusting the temperature
And water and alkali such as Na, K, Li, etc.
Metals, alkaline earth metals such as Ca, Mg, Ba, and boron
Add at least one water-soluble compound containing
And forming steps to form a forming base
A drying step of drying the green body; a green body;
Specially to perform a glaze process and a firing process using glaze
The method of manufacturing ceramics. 11. A process for increasing the rate of evaporation of water from the predetermined surface in order to move more alkali metal or alkaline earth metal to the predetermined surface in the drying step. The method for producing ceramics according to the above. 12. The method according to claim 11, wherein the ceramic is a toilet bowl, and the predetermined surface portion is inside a trap or a rim. 13. The method according to claim 11, wherein the porcelain is a basin, and the predetermined surface portion is inside an overflow. 14. The treatment is a treatment in which hot air or cold air is flown in order to move more alkali metal or alkaline earth metal to the surface where the alkali metal or alkaline earth metal is to be moved. The method of manufacturing a ceramic according to any one of claims 11 to 13, wherein 15. The treatment according to claim 1, wherein the heat is generated by a radiant heat source such as an infrared lamp in order to move the alkali metal or the alkaline earth metal more to the surface to which the alkali metal or the alkaline earth metal is to be moved. 14. The method for producing ceramics according to claim 11, wherein the process is a process of irradiating the ceramic. 16. The treatment is performed by applying microwave heating to a surface on which an alkali metal or an alkaline earth metal is to be moved, in order to move the alkali metal or the alkaline earth metal to the surface more, thereby promoting drying. The method for producing ceramics according to claim 11, wherein the processing is performed. 17. The method according to claim 10, wherein the water-soluble compound is any one of a carbonate, an acetate, a sulfate, and a citrate. 18. A method for producing the porcelain according to claim 1.
Method, SiO_Two, Al _TwoO_ThreeOf ceramic raw material mainly composed of
Base preparation that produces a base material by adjusting the temperature
And forming the molded body by molding using the raw material.
The steps of forming the ground and drying if necessary
After that, an alkali such as Na, K, Li
Metals, alkaline earth metals such as Ca, Mg, Ba, and boron
At least one water-soluble compound containing
A coating step of applying an aqueous solution containing the composition to the surface, a drying step,
Glazing process of applying glaze to the molding substrate, firing process
A method for manufacturing ceramics. 19. The method according to claim 18, wherein the application method in the application step is a spray method using ultrasonic waves.
The method for producing ceramics according to the above. 20. The method according to claim 19, wherein the ceramic is a toilet, and the predetermined surface is inside a trap or a rim. 21. The method according to claim 19, wherein the porcelain is a basin, and the predetermined surface portion is inside the overflow. 22. The raw material for raw materials includes at least one selected from kaolinite, dickite, halloysite, sericite, and pyrophyllite as essential components of a main mineral.
It contains clay minerals consisting of seeds and quartz, contains at least one mineral selected from mullite, corundum and diaspore as optional components, and optionally contains alkali such as feldspar as other components. The method according to claim 10, further comprising a mineral containing a metal or an alkaline earth metal such as dolomite. 23. The method according to claim 10, wherein the raw material has an average particle diameter of 1 to 20 μm as measured by a laser diffraction type particle size analyzer. 24. The method according to claim 10, wherein the forming method in the forming step is a slip casting. 25. The firing temperature in the firing step is 1
The temperature is 100 to 1300 ° C.
25. The method for producing a ceramic according to any one of the above items. 26. The method according to claim 10, wherein at least the amount of shrinkage in the longitudinal direction in the firing step is 7% or less. 27. In the forming step, a width 30, a thickness 15,
A test piece molded body having a length of 260 mm was produced, and the test piece molded body was supported at a span of 200 mm, and the amount of deflection when fired under the same firing conditions as that of the porcelain was 20 mm or less in terms of a fired body thickness of 10 mm. The method for producing ceramics according to claim 10, wherein: 28. A ceramic which can be produced by the method for producing a ceramic according to claim 10. 29. The porcelain according to claim 28, wherein the porcelain is any one of a basin, a urinal, a toilet, a baby bath, a toilet bowl, a hand basin, and a toilet tank.