Earthenware body material

Abstract

To provide a pottery body material from which a pottery having both productivity and quality can be produced with a high degree of freedom according to its purpose or application.SOLUTION: An earthenware body material comprising a first body material and a second body material, wherein the first body material and the second body material both comprise SiO2, Al2O3, and both or either one of K2O and Na2O as chemical constituent species, and the average particle size (D2) of the second body material is smaller than the average particle size (D1) of the first body material.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a ceramic body material, and more particularly to a ceramic body material that allows for the production of ceramics with high productivity and quality with a high degree of freedom depending on the purpose or use. [Background technology]

[0002] Known base materials for producing ceramic products such as sanitary ware include, for example, stone-based materials such as pottery stone and silica stone that form the skeleton of the ceramic, clays that impart plasticity during molding, and feldspars that act as melting agents during firing (JP Patent Publication No. 6-056516 (Patent Document 1), JP Patent Publication No. 2001-287981 (Patent Document 2), and JP Patent Publication No. 2011-116568 (Patent Document 3)). These ceramic base materials are mixed and processed into ceramic base materials. Depending on the type of raw material, the base materials can be mixed using a crushing and mixing method that uses crushing means such as a ball mill, or a stirring and mixing method that does not involve crushing. For example, in regions such as Japan, China, Taiwan, and Indonesia, there is a tendency to use base materials that are primarily composed of stone-based raw materials, and these base materials are made into base materials by a crushing and mixing method, while in regions such as the United States, Mexico, Thailand, and India, there is a tendency to use base materials that are primarily composed of powdered raw materials, and these base materials are made into base materials by a stirring and mixing method.

[0003] The stirring and mixing method generally makes it easy to design a precise body that makes the most of the properties of each raw material (additivity is likely to hold), and as a result, it is easy to create special bodies with properties such as low deformation and high strength, but it tends to have low adhesion (productivity) during molding.On the other hand, the crushing and mixing method involves crushing the raw materials, so it is generally difficult to design a precise body that makes the most of the properties of each raw material, but because stone-based raw materials can be used as raw materials, it tends to make it easier to create bodies with relatively high adhesion.

[0004] For example, Patent Document 1 describes a slip production method (A) in which all raw materials are mixed and stirred without a grinding step, and a slip production method (B) in which all raw materials are charged into a pot mill and ground to a predetermined average particle size (paragraph 0055). Patent Document 2 describes a production of a green material by wet grinding raw materials in a pot mill (paragraph 0019), and JP 2011-116568 A (Patent Document 3) describes a production of a green material by grinding and mixing raw materials in a ball mill (paragraph 0044).

[0005] In addition to the above-mentioned methods of producing a green material by either grinding and mixing or stirring and mixing all of the raw materials, when using a stone-based raw material, the stone-based raw material may be separately ground, and the ground stone-based raw material may be ground and mixed with the remaining raw materials to produce a green material. Furthermore, as an example of grinding and mixing some of the raw materials, stirring and mixing the remaining raw materials, and then mixing them to produce a green material, CN112094100A (Patent Document 4) describes a method of dividing multiple raw materials into two different groups based on the characteristics of each raw material, grinding and mixing one group, stirring and mixing the other, and mixing the resulting two different green slurries to produce a ceramic green slurry.

[0006] Specifically, Patent Document 4 proposes that a ceramic base slurry can be produced efficiently by mixing a slurry obtained by ball milling (ball milling and mixing) a raw material group including a hard porous raw material, a semi-porous semi-plastic raw material (a ball-shaped raw material A), and a soft plastic raw material (a ball-shaped raw material C), with a slurry obtained by mixing (stirring and mixing) a raw material group including a semi-porous semi-plastic raw material (a ball-shaped raw material B) and a soft plastic raw material (a ball-shaped raw material D). According to Patent Document 4, the hard porous raw material contained in only one of the slurries contains feldspar, silica, quartz, dolomite, etc. (Claim 7), the semi-porous semi-plastic raw material to which the ball-shaped raw materials A and B belong contains clays such as kaolin and china clay (Claim 8), and the soft plastic raw material to which the ball-shaped raw materials C and D belong contains clays such as ball clay and china clay (Claim 9).

[0007] The method for producing a ceramic base slurry described in Patent Document 4 involves dividing multiple base raw materials into two groups, mixing each group using a different mixing method, and finally mixing the two resulting slurries to obtain a single type of base slurry, making the production process somewhat complicated. Furthermore, the group of raw materials to be pulverized and mixed contains hard, porosity-containing raw materials, while the group of raw materials to be stirred and mixed does not. Therefore, the types of materials contained in the slurry obtained by pulverizing and mixing one group of raw materials differ from the types of materials contained in the slurry obtained by stirring and mixing the other group of raw materials. As a result, the base slurry obtained by mixing these two slurries may have unevenness during molding.

[0008] On the other hand, when focusing on the chemical composition after firing, ceramic base materials usually contain SiO2 and Al2O3 as the main components, and the ratio of these components changes depending on the base raw materials used (type and amount), firing conditions, etc. The above-mentioned Patent Documents 1 to 3 describe base materials that contain more SiO2 than Al2O3, and in which the composition ratio of SiO2 to Al2O3 is adjusted within that range.

[0009] In recent years, there has been an increasing demand for improved design and quality of sanitary ware, and ceramic products with sophisticated design and high quality (e.g., high strength and light weight) that can meet this demand. In addition, there is a demand for sanitary ware with excellent productivity or yield that can flexibly respond to variations in required design and quality. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Japanese Patent Application Publication No. 6-56516 [Patent Document 2] Japanese Patent Application Laid-Open No. 2001-287981 [Patent Document 3] Japanese Patent Application Laid-Open No. 2011-116568 [Patent Document 4] CN111393188A publication Summary of the Invention [Problem to be solved by the invention]

[0011] The inventors have now confirmed that pottery can be produced with both productivity and quality by mixing multiple base materials, each of which can be used to produce pottery independently and has a different average particle size. In particular, the inventors have confirmed that mixing multiple pottery base materials, each of which can be used to produce pottery independently, simplifies the manufacturing process, provides good productivity, and allows the mixing ratio to be appropriately determined depending on the purpose or use of the pottery to be produced, allowing for a high degree of freedom in pottery production. Furthermore, the inventors have confirmed that although the main chemical components of each mixed pottery base material (SiO2, Al2O3, and / or K2O and Na2O) are the same, the average particle sizes of the substances (particles) that actually constitute the base material vary, resulting in low unevenness even when mixed in various ratios, allowing for the production of pottery with high performance. The present invention is based on this finding.

[0012] Therefore, an object of the present invention is to provide a ceramic base material that allows for the production of ceramics that combine productivity and quality with a high degree of freedom depending on the purpose or application. [Means for solving the problem]

[0013] The ceramic base material according to the present invention is A ceramic base material including a first base material and a second base material, the first and second substrate materials each contain SiO, AlO, and either or both of KO and NaO as chemical constituents; The second base material has an average particle size (D2) smaller than the average particle size (D1) of the first base material. [Effects of the Invention]

[0014] According to the present invention, a ceramic base material is provided that allows for the production of ceramics that combine productivity and quality with a high degree of freedom depending on the purpose or application. DETAILED DESCRIPTION OF THE INVENTION

[0015] The ceramic body material of the present invention includes a first body material and a second body material. Both the first body material and the second body material contain at least SiO2, Al2O3, and either or both of K2O and Na2O as chemical components during firing. Because these chemical components are essential components during firing, i.e., because they can generate these chemical components during firing, the first body material and the second body material can each be used to produce ceramics independently. Because the ceramic body material of the present invention is a mixture (blend) of multiple body materials, each of which can be used to produce ceramics independently, the manufacturing process is simple and highly productive. Furthermore, the blend ratio of the first body material and the second body material can be appropriately determined depending on the purpose or use of the ceramic to be produced, allowing for high flexibility in ceramic production. This high degree of manufacturing flexibility improves yield.

[0016] The pottery base material according to the present invention may include a first base material and a second base material. The content ratio of the first base material and the second base material, that is, the mixing ratio of the first base material and the second base material is not particularly limited and may be arbitrarily determined. Since the mixing ratio of the first base material and the second base material, each of which can produce pottery alone, can be appropriately determined according to the purpose or use of the pottery to be produced, the degree of freedom in production is increased, and the performance of the first base material and the performance of the second base material can be selectively incorporated. As a result, a pottery base material having desired performance can be obtained. The performance (characteristics) of the pottery base material according to the present invention will be described later.

[0017] In the present invention, the "base material capable of producing pottery alone" means that a pottery having the performance usually required can be produced by a known method using only the base material, that is, without further adding other materials to the base material or performing any special treatment in the production process. In other words, it means that a molded body can be produced by a known molding method using only the base material, and further a fired body can be produced from the molded body by a known firing method, and further a pottery can be produced through the cooling of the fired body.

[0018] In addition, the average particle diameter (D1) of the first base material and the average particle diameter (D2) of the second base material of the pottery base material according to the present invention are different, and D2 is smaller than D1. That is, although the main chemical component species (both or either one of SiO2, Al2O3, and K2O and Na2O) are the same for each base material used in combination, the average particle diameter of the substances (particles) actually constituting the base material is different (D2 < D1). Therefore, even when mixed in various mixing ratios, there is little unevenness during molding and firing, and a pottery having high performance can be produced.

[0019] First base material raw material The first base material is preferably made using pottery stone as a raw material. Minerals such as quartz, sericite, and kaolin that make up the pottery stone provide the molded body of the first base material with inking properties and also serve as the main skeleton of the molded body. Improved inking properties improve productivity. Examples of pottery stone that can be used include sericite pottery stone and kaolin pottery stone.

[0020] The first base material is preferably made primarily from stone-based raw materials. Examples of stone-based raw materials include pottery stone, feldspar, and dolomite. Feldspar and dolomite impart densification to the fired body of the first base material. Dolomite can also lower the firing temperature, thereby reducing energy costs and enabling economical production of ceramic products, and is suitable for industrial (mass) production.

[0021] Feldspars include feldspar minerals such as potassium feldspar, soda feldspar, and anorthite, nephelite, natural glass, frit, and the like. These raw materials are abundantly contained in various feldspar raw materials, nepheline syenite, Cornish stone, mackerel, glassy volcanic rocks, and various pottery stones, and are also partially contained in clayey raw materials. Among these feldspars, those rich in K2O and Na2O as alkaline components are particularly preferred, and examples thereof include potassium feldspar, soda feldspar, and nephelite. Furthermore, when it is desired to minimize the amount of quartz in the raw materials, it is preferable to use nepheline syenite, which contains essentially no quartz in its composition. These feldspar minerals melt during firing to form a glass phase, but some may remain unmelted as crystals.

[0022] According to a preferred embodiment of the present invention, the raw materials for producing the first base material preferably contain pottery stone, clay (powder), and feldspar as main components.

[0023] Examples of clays include clay minerals such as kaolinite, halloysite, metahalloysite, dickite, and pyrophyllite, and clay-like micas such as sericite and illite. These minerals are abundantly contained in clay materials such as frog's eye clay, kibushi clay, kaolin, ball clay, and china clay, as well as in various pottery stones, and are also partially contained in feldspar materials. Among these clays, kaolinite and halloysite are particularly effective in improving plasticity during molding, while sericite is highly effective in lowering the firing temperature of the base material. These clay minerals melt during firing to form a glass phase, but some may remain unmelted as crystals.

[0024] In the present invention, the raw materials for preparing the first base material may contain α-alumina. For example, α-alumina may be separately pulverized and added to the above-mentioned base materials, and then these may be pulverized and mixed to form the base material. Furthermore, the raw materials for preparing the first base material do not necessarily need to contain α-alumina.

[0025] Production method In the present invention, the first base material is preferably prepared by grinding and mixing the above-described raw materials (also referred to as "first base material"). Because the first base material contains a stone-based raw material as its main component, grinding and mixing these raw materials allows for the production of a base material with a desired average particle size. The average particle size (D1) of the first base material is preferably 3 μm to 15 μm, more preferably 5 μm to 12 μm, and is larger than the average particle size (D2) of the second base material described below. In particular, when the first base material contains quartz or α-alumina, which constitute pottery stone, setting D1 within the above range ensures good strength and thermal shock resistance. The average particle size of the base material can be measured using a laser diffraction particle size analyzer (e.g., a Mastersizer 3000 manufactured by Malvern or a Microtrac MT-3000 manufactured by Nikkiso Co., Ltd.) and expressed as the particle size at 50% cumulative volume (D50).

[0026] Grinding and mixing method The first base material can be pulverized and mixed by known methods using a ball mill, planetary ball mill, jet mill, etc. After pulverization, coarse particles can be removed using a classifier such as a sieve, if necessary. Classification can be performed by known methods using a vibrating sieve, ultrasonic sieve, various screeners, centrifuge, etc.

[0027] composition In the present invention, the first base material preferably contains, as an overall chemical composition after firing, 50-75 wt% SiO2, 17-40 wt% Al2O3, and 1-10 wt% K2O + Na2O. The first base material preferably contains 25-70 wt% glass phase and 75-30 wt% crystalline phase. The chemical composition of the main components constituting the glass phase is preferably 50-80 wt% SiO2, 10-40 wt% Al2O3, and 4-12 wt% K2O + Na2O, assuming the entire glass phase as 100%. The mineral composition of the main components constituting the crystalline phase is preferably 0-60 wt% α-alumina, 0-20 wt% quartz, and 2-20 wt% mullite, assuming the entire base as 100%. According to one embodiment of the present invention, the first green material may be a green material (e.g., a vitreous green material) that does not contain α-alumina as a major mineral component constituting the crystalline phase. According to one embodiment of the present invention, it is preferable that the amount of SiO2 contained in the first green material is greater than the amount of SiO2 contained in the second green material, and that the amount of Al2O3 contained in the first green material is less than the amount of Al2O3 contained in the second green material. According to one embodiment of the present invention, it is preferable that the SiO2 / Al2O3 ratio in the first green material is greater than 1. According to one embodiment of the present invention, it is preferable that the SiO2 / Al2O3 ratio in the first green material is greater than the SiO2 / Al2O3 ratio in the second green material.

[0028] The overall composition of the first base material when fired may be, for example, the composition shown in Table 1 below.

[0029] [Table 1]

[0030] Second base material raw material The second base material is preferably made from silica and α-alumina as raw materials. The quartz and α-alumina that make up the silica form the main skeleton of the compact of the second base material, which is expected to result in low deformation and high strength.

[0031] The second base material is preferably made primarily from powdered raw materials. Examples of powdered raw materials include silica, α-alumina, feldspar, china clay, and ball clay. The feldspar powder imparts densification to the fired body of the second base material. Feldspars have already been described as raw materials for the first base material.

[0032] According to a preferred embodiment of the present invention, the raw materials for producing the second base material preferably contain silica (powder), α-alumina (powder), clay (powder), and feldspar (powder) as main components, as described above for the raw materials for the first base material.

[0033] Production method In the present invention, the second base material is preferably prepared by stirring and mixing the above-mentioned raw materials (also referred to as the "second base material"). Since the second base material mainly contains powdered raw materials, if these powdered raw materials have the desired average particle size, the base material can be obtained simply by stirring and mixing. The stirring and mixing method is the simplest method because it allows the particle size distribution of each raw material to be controlled independently. If the powdered raw materials do not have the desired average particle size, appropriate adjustments can be made, such as by adding a raw material pulverization process using a ball mill or the like. The average particle size (D2) of the second base material is preferably 1 μm to 13 μm, more preferably 3 μm to 10 μm, and is smaller than the average particle size D1 of the first base material. In particular, when the second base material contains quartz or α-alumina, which constitute silica stone, good strength and thermal shock resistance can be obtained by setting D2 within the above range.

[0034] Stirring and mixing method The second raw material can be stirred and mixed by a known method, for example, using an Eirich Intensive Mixer (Maschinenfabrik Gustav Eirich GmbH). After stirring, if necessary, coarse particles may be removed using a classifier such as a sieve.

[0035] composition In the present invention, the second base material preferably has an overall chemical composition after firing of 20-45 wt% SiO2, 50-75 wt% Al2O3, and 1-10 wt% K2O + Na2O. The second base material preferably has a glass phase of 25-70 wt% and a crystalline phase of 75-30 wt%. The chemical composition of the main components constituting the glass phase is preferably 50-80 wt% SiO2, 10-40 wt% Al2O3, and 4-12 wt% K2O + Na2O, based on the entire glass phase being 100%. The mineral composition of the main components constituting the crystalline phase is preferably 10-60 wt% α-alumina, 0-20 wt% quartz, and 2-20 wt% mullite, based on the entire base being 100%. According to one embodiment of the present invention, it is preferred that the amount of SiO2 contained in the second green material is less than the amount of SiO2 contained in the first green material, and that the amount of Al2O3 contained in the second green material is greater than the amount of Al2O3 contained in the first green material. According to one embodiment of the present invention, it is preferred that the Al2O3 / SiO2 ratio in the second green material is greater than 1. According to one embodiment of the present invention, it is preferred that the Al2O3 / SiO2 ratio in the second green material is greater than the Al2O3 / SiO2 ratio in the first green material.

[0036] The overall composition of the second base material when fired may be, for example, the compositions shown in Tables 2 and 3 below.

[0037] [Table 2]

[0038] [Table 3]

[0039] Ceramic body material according to the present invention The ceramic body material according to the present invention can be produced by mixing the first and second body materials in any desired ratio. In other words, the mixing ratio can be determined appropriately depending on the purpose or use of the ceramic to be produced, and the properties of the first and second body materials can be selectively incorporated to produce a ceramic body material with the desired properties. In one aspect of the present invention, there is provided a method for producing a ceramic body material according to the present invention, the method comprising: (a) mixing first raw materials to prepare a first base material having a first average particle size (D10); (b) mixing second raw materials to prepare a second raw material having a second average particle size (D20); (c) mixing the first base material with the second base material; Including, The first and second raw materials each contain SiO, AlO, KO, and NaO as chemical constituents; After mixing the first base material and the second base material (after step (c)), the average particle size (D2) of the second base material is smaller than the average particle size (D1) of the first base material. The first and second base materials may be mixed by either grinding or stirring, and the mixing is preferably carried out within a range that does not significantly change the average particle size (D10) of the first base material or the average particle size (D20) of the second base material.

[0040] molding The ceramic base material according to the present invention can be formed by known methods such as casting, extrusion, wheel casting, and press molding, and casting is preferably used for large and complex shaped products such as sanitary ware.

[0041] Firing The ceramic body formed according to the present invention can be fired in a gas furnace or an electric furnace, and the firing temperature and firing time can be appropriately determined.

[0042] composition The ceramic body material of the present invention can be freely mixed with the first and second body materials to achieve a desired composition. For example, the overall chemical composition after firing, the glass phase, the crystalline phase, the chemical composition of the main components constituting the glass phase, and the mineral composition of the main components constituting the crystalline phase can each be freely controlled to fall within a range between the values ​​for the first body material and the second body material. Because the composition of the ceramic body material of the present invention can be freely controlled as described above, it can exhibit the various performance properties described below.

[0043] Performance (characteristics) The ceramic base material according to the present invention has the above-mentioned composition, and thus can have the following various properties.

[0044] Water absorption rate The ceramic base material of the present invention allows ceramics with a wide range of water absorption rates, from 4% to 10%, to be produced with a high degree of freedom according to the purpose and use. The water absorption rate is a value measured in accordance with JIS A1509-3. A fired sample of the base material is dried at 110°C for 24 hours, cooled, and then its mass W1 is measured. The sample is then immersed in water in a desiccator and held in a vacuum for 1 hour to forcibly saturate the open pores with water, and its mass W2 is then measured. The water absorption rate is calculated using the following formula. Water absorption rate=(W2-W1) / W1×100(%)

[0045] Firing deformation amount The pottery base material according to the present invention can be used to produce pottery whose firing deformation can be freely controlled within a wide range of practically acceptable values, from 4 mm to 13 mm. The amount of deformation during firing is determined by supporting an unfired test piece 30 mm wide, 15 mm thick, and 260 mm long at a span of 200 mm during firing, and measuring the amount of deflection after firing and the thickness of the test piece. Since the amount of deflection is inversely proportional to the square of the thickness of the test piece after firing, the amount of deflection converted to a thickness of 10 mm using the following formula is the amount of deformation during firing. Firing deformation amount = measured deflection amount x (thickness of test piece after firing) 2 / 10 2

[0046] Firing shrinkage The ceramic base material according to the present invention makes it possible to produce ceramics whose firing shrinkage can be freely controlled within a wide range of 2.5% to 7.0%, which is practically acceptable. The firing shrinkage rate is the longitudinal shrinkage rate of a fired test piece of the base material, 25 mm wide, 5 mm thick, and 230 mm long, which is heated to 1000°C in 4 hours, then further heated to 1200°C in 2 hours, held at 1200°C for 1 hour, and then naturally cooled to room temperature.

[0047] Pottery produced from the pottery base material of the present invention has excellent designability and can flexibly accommodate design variations because the firing deformation and firing shrinkage can be freely controlled within a wide range that is practically acceptable. For example, while the firing deformation and firing shrinkage of the first base material are relatively high, by reducing the mixing ratio of the first base material to the second base material and increasing the mixing ratio of the latter, the firing deformation and firing shrinkage of the pottery base material can be controlled toward those of the second base material, i.e., low. Furthermore, while the water absorption of the second base material is relatively high, by increasing the mixing ratio of the first base material to the second base material and decreasing the mixing ratio of the latter, the water absorption of the pottery base material can be controlled toward those of the first base material, i.e., low.

[0048] strength The pottery base material according to the present invention can be used to produce pottery having good strength within a wide range of 80 MPa to 120 MPa. Strength is measured by preparing a test piece of φ13 x 130 mm and conducting a three-point bending test using an autograph under conditions of a span of 100 mm and a crosshead speed of 2.5 mm / min.

[0049] Thermal shock resistance (rapid cooling resistance) The ceramic base material according to the present invention can be used to produce ceramics having a thermal shock resistance of preferably about 120°C to 150°C, more preferably about 130°C to 150°C. Thermal shock resistance is evaluated by holding a sintered test piece, 25mm wide x 10mm thick x 110mm long, at a specified temperature for at least 30 minutes, then immersing it in water to rapidly cool it, and checking for the occurrence of cracks. The rapid cooling temperature is increased by 10°C increments, and the maximum temperature difference at which no cracks occur is evaluated as thermal shock resistance.

[0050] Thermal expansion The ceramic base material of the present invention is 70 x 10 -7 It is possible to manufacture ceramics with a thermal expansion coefficient of about 1 / °C. The thermal expansion is evaluated by measuring the linear thermal expansion coefficient using a differential dilatometer with a compression load method in a measurement temperature range of 50 to 600°C using a sintered test piece having a diameter of 5 mm and a length of 20 mm.

[0051] Penetration resistance The ceramic body material according to the present invention can produce ceramic having puncture resistance. The inventors have confirmed that a non-vitrified body material alone does not provide sufficient puncture resistance, but the ceramic body material according to the present invention, which includes a first body material and a second body material, can provide good puncture resistance. To test for crazing resistance, a sample is prepared by spraying Bristol glaze, which is commonly used for sanitary ware, onto the base material and then firing it. Next, a crazing test is conducted using an autoclave in accordance with JIS A 5207, and the test specimen is immersed in red ink and visually evaluated for the occurrence of crazing.

[0052] The pottery produced from the pottery base material of the present invention has good strength, thermal shock resistance and puncture resistance, and is therefore of excellent quality. [Example]

[0053] The present invention will be specifically described based on the following examples, but the present invention is not limited to these examples.

[0054] Preparation of the first base material The raw materials were approximately 48% by weight of sericite pottery stone and kaolin pottery stone, which are skeleton-forming materials; approximately 35% by weight of china clay (powder) and ball clay (powder), which are plastic materials; approximately 15% by weight of feldspar, which is the main sintering aid; and approximately 2% by weight of dolomite. An appropriate amount of water and sodium silicate as a deflocculating agent were added, and the mixture was placed in a ball mill. After grinding, the powder was wet-ground until the particle size of the ground slurry measured using a laser diffraction particle size distribution analyzer showed that 58% was 10 μm or less and the 50% average particle size (D50) was approximately 8.0 μm, yielding the first base material.

[0055] Preparation of the second substrate material The raw materials were approximately 64% by weight of silica stone and α-alumina, which are skeleton-forming materials, approximately 32% by weight of china clay (powder) and ball clay (powder), which are plastic materials, and approximately 4% by weight of feldspar, which is a sintering aid. An appropriate amount of water and sodium silicate as a deflocculating agent were added, and the mixture was placed in an Eirich Intensive Mixer (Maschinenfabrik Gustav Eirich GmbH). The particle size of the stirred and mixed base slurry was measured using a laser diffraction particle size distribution analyzer, and a second base material was obtained, with 75% of the particles being 10 μm or less and the 50% average particle size (D50) being approximately 5.0 μm.

[0056] Preparation of ceramic base materials The first and second body materials were mixed in the mixing ratios shown in Table 4 to obtain four types of ceramic body materials. The mixing was carried out by stirring.

[0057] Preparation of compacts Each of the obtained ceramic base materials was molded by slip casting using a plaster mold to obtain a molded body.

[0058] Preparation of fired body The resulting compacts were each fired in an electric furnace to obtain fired bodies, with the maximum temperature on the heat curve being approximately 1200° C. The fired bodies thus obtained were subjected to various evaluations, as described below.

[0059] The overall chemical composition, crystalline phase, and glass phase of each ceramic body material after firing are shown in Table 4.

[0060] evaluation The properties of the four types of ceramic body materials were measured as follows, and the results are shown in Table 4.

[0061] Water absorption rate Water absorption was measured in accordance with JIS A1509-3. A fired sample of the base material was dried at 110°C for 24 hours, cooled, and then its mass W1 was measured. The sample was then immersed in water in a desiccator and held in a vacuum for 1 hour to forcibly saturate the open pores with water, and its mass W2 was measured. Water absorption was calculated using the following formula. Water absorption rate=(W2-W1) / W1×100(%)

[0062] Firing deformation amount The amount of deformation during firing was determined by supporting an unfired test piece 30 mm wide, 15 mm thick, and 260 mm long at a span of 200 mm during firing, and measuring the amount of deflection after firing and the thickness of the test piece. Since the amount of deflection is inversely proportional to the square of the thickness of the test piece after firing, the amount of deflection converted to a thickness of 10 mm using the following formula was taken as the amount of deformation during firing. Firing deformation amount = measured deflection amount x (thickness of test piece after firing) 2 / 10 2

[0063] Firing shrinkage The firing shrinkage rate was determined as the longitudinal shrinkage rate of a fired test piece of the base material, 25 mm wide, 5 mm thick, and 230 mm long, which was heated to 1000°C in 4 hours, then further heated to 1200°C in 2 hours, held at 1200°C for 1 hour, and then naturally cooled to room temperature.

[0064] strength Strength was measured by preparing a sintered test piece of the base material measuring φ13×130 mm and performing three-point bending measurements using an autograph under conditions of a span of 100 mm and a crosshead speed of 2.5 mm / min.

[0065] Thermal shock resistance (rapid cooling resistance) Thermal shock resistance was evaluated by holding a sintered test piece (25mm wide x 10mm thick x 110mm long) at a specified temperature for at least 30 minutes, then immersing it in water for rapid cooling and checking for the occurrence of cracks. The rapid cooling temperature was increased in 10°C increments, and the maximum temperature difference at which no cracks occurred was taken as the thermal shock resistance.

[0066] Thermal expansion The thermal expansion was evaluated by measuring the linear thermal expansion coefficient of a sintered test piece having a diameter of 5 mm and a length of 20 mm using a differential dilatometer under a compressive load method in a measurement temperature range of 50 to 600°C.

[0067] Penetration resistance To test for crazing resistance, Bristol glaze, which is commonly used for sanitary ware, was sprayed onto the base material and then fired to prepare samples. Next, a crazing test was conducted using an autoclave in accordance with JIS A 5207, and the fired samples were immersed in red ink and visually evaluated for the occurrence of crazing.

[0068] [Table 4]

Claims

1. A ceramic body material including a first body material and a second body material, The first base material and the second base material both contain SiO as a chemical component species. ２ , Al ２ O ３ , and K ２ O and Na ２ O or both, A ceramic base material, wherein the average particle size (D2) of the second base material is smaller than the average particle size (D1) of the first base material.

2. The ceramic base material according to claim 1, wherein the first base material includes a material derived from pottery stone as a skeleton material, and the second base material includes a material derived from silica stone and α-alumina as a skeleton material.

3. The ceramic base material according to claim 1 or 2, wherein the first base material contains a material derived from a stone-based raw material as a main component, and the second base material contains a material derived from a powder raw material as a main component.

4. The ceramic base material according to any one of claims 1 to 3, wherein the first base material comprises a ground mixture of a first base raw material, and the second base material comprises an agitated mixture of a second base raw material.

5. 5. The method according to claim 4, wherein the first base material comprises pottery stone, clay (powder), and feldspar as main components, and the second base material comprises silica stone (powder), α-alumina (powder), clay (powder), and feldspar (powder) as main components.

6. The pottery base material according to any one of claims 1 to 5, wherein the firing deformation amount is 4 mm to 13 mm.

7. The pottery base material according to any one of claims 1 to 5, wherein the firing shrinkage rate is 2.5 to 7.0%.

8. The ceramic base material according to any one of claims 1 to 5, having a water absorption rate of 4 to 10%.

9. 1. A method for producing a ceramic body material, comprising: The first raw material is mixed to form a powder having a first average particle diameter (D1 ０ ), and The second raw material is mixed to form a second average particle diameter (D2 ０ ), and mixing the first base material with the second base material; Including, Both the first and second raw materials contain SiO as a chemical component. ２ , Al ２ O ３ , and K ２ O and Na ２ O or both, After mixing the first base material and the second base material, the average particle size (D2) of the second base material is smaller than the average particle size (D1) of the first base material. A method characterized by:

10. The method of claim 9, wherein the first green body material comprises pottery stone and the second green body material comprises silica stone and alpha-alumina.

11. The method according to claim 9 or 10, wherein the first green raw material contains a stone-based raw material as a main component, and the second green raw material contains a powder raw material as a main component.

12. The method according to any one of claims 9 to 11, wherein the first base material comprises pottery stone, clay (powder), and feldspar as main components, and the second base material comprises silica stone (powder), α-alumina (powder), clay (powder), and feldspar (powder) as main components.

13. The method according to any one of claims 9 to 12, wherein the first green raw materials are mixed by a grinding and mixing method to prepare the first green material, and the second green raw materials are mixed by a stirring and mixing method to prepare the second green material.

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