JP2009215115A - Composition for low-temperature firing porcelain, and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a composition for low-temperature firing porcelains which is sintered at a low temperature of about 1,100°C and has a broad firing temperature range, and a manufacturing method thereof. <P>SOLUTION: The composition comprises a non-clay component containing at least one mineral component selected from a component C being a mineral containing Li<SB>2</SB>O as a main component of an alkali metal component, a component A being a mineral containing Na<SB>2</SB>O as a main component of an alkali metal component, and a component B being a mineral containing K<SB>2</SB>O as a main component of an alkali metal component; and a clay component, wherein the clay component is contained in 30 to 50 wt.% with respect to the whole composition; and the component C is contained in 8.3 to 75 wt.% with respect to the whole non-clay component. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a composition for low-temperature fired ceramics that is sintered at a low temperature of about 1100 ° C. and has a wide firing temperature range, and a method for producing a low-temperature fired ceramic.

Conventionally, the raw material composition for producing porcelain is generally feldspar-silica-clay system, sericite-silica system, feldspar-calcium phosphate-clay system, etc., but these have a firing temperature of 1200 ° C. Need ~ 1350 ° C.
Among the ceramics that are currently manufactured, the firing temperature of porcelain is about 1350 ° C for Mino ware, about 1300 ° C for Arita ware and Kutani ware, 1200 to 1300 ° C for bone china, and baked at a lower temperature of about 1100 ° C. What you do is not manufactured.

  Research on porcelain fired at a low temperature of about 1100 ° C has been carried out in various places in the past, and low-temperature fired porcelain has been developed in glass-clay, phosphate-clay, fine calcium carbonate-clay, etc. (For example, Patent Document 1, Patent Document 2, etc.). However, because of the disadvantages such as “low plasticity of the soil and difficult to mold”, “narrow firing temperature range” and “difficult to process raw materials”, it is almost practical as a porcelain generally used for tableware etc. The current situation is that it has not been realized.

  In addition, as a special porcelain used as an electronic material, there is a glass-clay type material that is baked at 1100 ° C. or less to become porcelain (see Patent Document 3). However, there are problems such as high cost, narrow firing temperature range, and low plasticity.

In recent years, the rise in fuel costs accompanying the rise in crude oil prices has become a serious problem. In addition, while reducing the environmental burden in the industry, it is also an important issue to reduce carbon dioxide emissions during the ceramic manufacturing process. Also from these things, development of the base material which can be baked at lower temperature is anxious.
JP 2005-162592 A JP-A-10-95657 Japanese Patent Laid-Open No. 11-335156

  The present invention was made to address such problems, and can be sintered at a low temperature of about 1100 ° C., and has a wide firing temperature range, and a low-temperature fired ceramic composition using the composition. The object is to provide a method for manufacturing porcelain.

上記三角座標（１）において、Ａ、Ｂ、およびＣ各成分の頂点の値は、（ 100 重量％−粘土成分の重量％）を、各頂点の対辺は 0 重量％をそれぞれ表す。
また、本発明の低温焼成磁器用組成物は、上記Ａ成分がネフェリンサイアナイトまたはソーダ長石であり、上記Ｂ成分がカリ長石であり、上記Ｃ成分がペタライトであることを特徴とする。 The composition for low-temperature fired porcelain of the present invention includes a C component which is a mineral containing Li ₂ O as a main component of an alkali metal component, an A component which is a mineral containing Na ₂ O as a main component of an alkali metal component, and K _2. A non-clay component containing at least one mineral component selected from the B component, which is a mineral containing O as a main component of the alkali metal component, and a clay component, It is characterized by containing 50 wt% and not more than 8.3 to 75 wt% of the C component with respect to the whole non-clay component.
The component A is a mineral containing 5 to 22% by weight of Na ₂ O, the component B is a mineral containing 4 to 17% by weight of K ₂ O, and the component C is 3 to 12% by weight of Li ₂ O. % Minerals.
Moreover, as a non-clay component excluding the clay component, the composition range of the A component, the B component, and the C component is represented by a hatched range of the following triangular coordinate (1).

In the triangular coordinate (1), the value of the vertex of each component of A, B, and C represents (100% by weight−% by weight of the clay component), and the opposite side of each vertex represents 0% by weight.
The composition for low-temperature fired porcelain of the present invention is characterized in that the A component is nepheline sianite or soda feldspar, the B component is potassium feldspar, and the C component is petalite.

The method for producing a low-temperature fired porcelain of the present invention comprises a C component which is a mineral containing Li ₂ O as a main component of an alkali metal component, an A component which is a mineral containing Na ₂ O as a main component of an alkali metal component, and K _2. A step of mixing a clay component with a non-clay component containing at least one mineral component selected from the B component, which is a mineral containing O as a main component of the alkali metal component, and the average particle size of the mixed components The method includes a step of pulverizing to 11 μm or less and a step of kneading and molding the pulverized components and firing at 1000 ° C. or more and less than 1200 ° C.

The composition for low-temperature fired porcelain of the present invention comprises a non-clay component containing a C component as a mineral, at least one mineral component selected from the A component and the B component, and a clay component, Since the clay component is contained in an amount of 30 to 50% by weight with respect to the whole and the C component is included as an essential component as a non-clay component excluding the clay component, it can be made porcelain by firing at about 1100 ° C. Further, at a firing temperature of about 1100 ° C., the firing temperature range can be 25 ° C. or more.
In particular, by containing a certain amount of clay component, the above A component is nepheline sianite, the above B component is potash feldspar, and the above C component is petalite, making it porcelain at about 1100 ° C, water absorption 0.5% by weight or less, bulkiness A porcelain capable of suppressing the change in density to a range of 0.03 g / cm ³ in a firing temperature range of 25 to 100 ° C. is obtained.
The raw materials used are all natural raw materials, and are advantageous in that they are inexpensive, easy to use such as pulverization and easy to use, and are mined in large quantities and relatively easy to obtain.

Conventionally, many feldspar-silica-clay-based porcelains are fired at a high temperature of about 1350 ° C., and this mainly uses potash feldspar.
In the present invention, as an alkali metal oxide-containing substance having a low solubility in water, feldspars include nepheline sianite containing sodium as an alkali metal, potassium feldspar containing potassium, and petalite containing lithium in a specific range. Mix in proportions. By these, mixed alkali effect was exhibited, and it is thought that sintering at a low temperature of about 1100 ° C., which was difficult with conventional feldspar-silica-clay ceramics, is possible.

The method for producing a low-temperature fired porcelain of the present invention comprises a step of mixing at least one mineral component selected from the C component, the A component, and the B component, which are minerals, and a clay component, and an average of the mixed components. Since it includes a step of pulverizing to a particle size of 11 μm or less and a step of kneading and forming the pulverized components and firing at 1000 ° C. or more and less than 1200 ° C. A ligation can be obtained. Further, since it has a wide firing temperature range of about 1075 ° C. to 1150 ° C., it can also be used in ordinary ceramic firing furnaces having uneven sintering temperatures.
Further, since three kinds of feldspars containing a certain amount of clay and hardly affecting plasticity are mixed and used, the plasticity of the clay can be maintained well and molding is easy.

The composition for low-temperature fired porcelain of the present invention includes a C component which is a mineral containing Li ₂ O as a main component of an alkali metal component, an A component which is a mineral containing Na ₂ O as a main component of an alkali metal component, and K _2. It includes at least one mineral component selected from the B component, which is a mineral containing O as a main component of the alkali metal component, and a clay component.

As the component A, a mineral component containing SiO ₂ and Al ₂ O ₃ as main components, containing 5 to 22% by weight of Na ₂ O, and having a residue of 5% by weight or less can be preferably used.
When Na ₂ O is less than 5% by weight, it does not act as a mineral containing Na ₂ O, and minerals exceeding 22% by weight are difficult to use.
As the mineral component, nepheline sianite, soda feldspar, nepheline, zeolite and the like can be used. Among these, nepheline sianite is preferable because it is easily available and a wide firing temperature range can be obtained.

As the B component, as main components SiO _2, Al ₂ O _3, includes K ₂ O 4 to 17 wt%, ignition residue content of 5% by weight of the mineral component can be preferably used.
When K ₂ O is less than 4% by weight, it does not act as a mineral containing K ₂ O, and minerals exceeding 17% by weight are difficult to use.
As the mineral component, potassium feldspar, sericite, muscovite, leucite and the like can be used. Among these, potassium feldspar is preferable because it is easily available and easy to handle.

Examples of the C component, the main component SiO _2, Al ₂ O _3, the Li ₂ O containing 3 to 12 wt%, ignition residue content of 5% by weight of the mineral component can be preferably used.
When Li ₂ O is less than 3% by weight, it does not show an action as a mineral containing Li ₂ O, and when it exceeds 12% by weight, it is difficult to use.
Examples of the mineral component include petalite, spodumene, eucryptite, ambrigonite, and lipidoid. Among these, petalite is preferable because it does not undergo a sudden volume change due to heating, is rich in resources, and is easily available.

As the clay component, it is possible to use a clay component containing SiO ₂ and Al ₂ O ₃ in a total of 80% by weight or more, and a residual residue of 8% by weight or more, preferably 10% by weight or more.
Examples of the clay component include kaolins such as New Zealand (NZ) kaolin and Hedong kaolin, Sasame clay, Kibushi clay, bentonite and the like. Of these, NZ kaolin is preferred because it has few impurities.

In the present invention, when the blending ratio of each component is changed, the firing temperature range is measured by measuring the water absorption rate and bulk density of a sintered body obtained by pulverizing and mixing the components, followed by kneading, forming and firing. Can be determined. It can be said that the firing temperature range is wider as the fluctuation range from the maximum bulk density is smaller in the firing temperature range where the water absorption is within 0.5% by weight.
For example, FIG. 1 shows changes in water absorption and bulk density with respect to the firing temperature when the proportions of the clay components are changed in the proportions shown in Table 1 for the components shown in Table 1. Table 2 shows the firing temperature range. In Table 2, A component, B component, and C component were mixed in equal amounts. For example, when the blending amount of (A + B + C) is 60% by weight, the A component, the B component, and the C component are each 20% by weight. Moreover, the raw material before baking used the sieve passage of 500 micrometers of openings, and the test piece press-molded by the pressure of 50 MPa was hold | maintained at each baking temperature for 1 hour.

As shown in FIG. 1 and Table 2, when the clay component is small, the firing temperature range is narrowed, and when the clay component is large, the firing temperature is increased and the firing temperature range is narrowed.
The composition for low-temperature fired porcelain of the present invention contains 30 to 50% by weight, preferably 35 to 45% by weight of the above clay component. When the clay component is less than 30% by weight, the firing temperature range becomes narrower, and when the clay component exceeds 50% by weight, the sintering temperature becomes less than 0.5% by weight and the low temperature firing becomes difficult. Also, the change in bulk density becomes large and it becomes difficult to obtain a uniform sintered body.

The composition for low-temperature fired porcelain of the present invention contains the C component as an essential component with respect to 30 to 50% by weight of the clay component.
Preferably, C component is 8.3 to 75% by weight with respect to the whole non-clay component excluding the clay component, more preferably, the composition of A component, B component and C component as non-clay component excluding the clay component The range is within the hatched range of the triangular coordinate (1).
For example, when the clay component is 40% by weight and all the remaining components are non-clay components, each vertex of the triangular coordinates is 60% by weight, the A component is 0 to 55% by weight, the B component is 0 to 55% by weight, C The component is in the range of 5 to 45% by weight, and the range in which the total of component A, component B and component C is 60% by weight is preferable.

三角座標（２）において、例えば黒点とこの黒点付近に記載された 1100/75 の数値は、黒点が三角座標上でのＡ成分とＢ成分とＣ成分との配合割合を示し、吸水率が 0.5 ％以下となる最低焼成温度と、かさ密度の変動幅が最大値−0.03 ｇ／ｃｍ³の範囲に収まる焼成温度幅を示す。なお、粘土成分 40 ％、Ｃ成分 60 ％の場合、1250 ℃以下の焼成温度では焼結体が得られなかった。
三角座標（２）に示すように、Ａ成分とＢ成分とＣ成分との合計が 60 重量％となる配合において、 1100℃以内で 50 ℃以上の焼成幅を得ようとすれば、Ａ成分は 0 〜 45 重量％、Ｂ成分は 0 〜 45 重量％、Ｃ成分は 15 〜 45 重量％の範囲で、Ａ成分とＢ成分とＣ成分との合計が 60 重量％となる範囲が好ましい。その範囲は、三角座標（２）に示す斜線で示す範囲内である。
また、 1080℃以内で 75 ℃以上の焼成幅を得ようとすれば、Ａ成分とＢ成分とＣ成分との範囲は、太線で示す 1080℃で囲まれた範囲内である。 The temperature at which the bulk density reaches the maximum value is measured by changing the proportion of each component and measuring the change in the water absorption rate and the bulk density with respect to the firing temperature in the formulation where the total of the A component, the B component, and the C component is 60% by weight. The results of obtaining the firing temperature range are shown in triangular coordinates (2) below.

In triangular coordinate (2), for example, the black point and the numerical value of 1100/75 written in the vicinity of the black point indicate the blending ratio of the A component, the B component and the C component on the triangular coordinate, and the water absorption is 0.5. % Firing temperature range within which the fluctuation range of bulk density falls within the range of the maximum value −0.03 g / cm ³ . When the clay component was 40% and the C component was 60%, a sintered body could not be obtained at a firing temperature of 1250 ° C. or lower.
As shown in the triangular coordinate (2), in a composition where the sum of the A component, the B component and the C component is 60% by weight, if an attempt is made to obtain a firing width of 50 ° C. or more within 1100 ° C., the A component is A range of 0 to 45% by weight, a B component of 0 to 45% by weight, a C component of 15 to 45% by weight and a total of A, B and C components of 60% by weight is preferred. The range is within the range indicated by the oblique lines shown in triangular coordinates (2).
Moreover, if it is going to obtain the baking width | variety of 75 degreeC or more within 1080 degreeC, the range of A component, B component, and C component will be in the range enclosed by 1080 degreeC shown with a thick line.

The low-temperature fired ceramic composition of the present invention is preferably composed of the clay component and the non-clay component.
In addition to the above-mentioned clay component and non-clay component, glass frit, magnesium carbonate, magnesium phosphate, zinc oxide, silicon dioxide, aluminum oxide, titanium oxide, zircon, zirconium oxide, mullite, oxidation can be used if the content is 10% by weight or less. Components such as iron, copper oxide, manganese oxide, cobalt oxide, nickel oxide, and chromium oxide may be included.

A method for producing the low-temperature fired porcelain of the present invention will be described.
The above-mentioned A component, B component, C component, and clay component are mixed by a wet method or a dry method. For example, in the wet method, each component is put into a ball mill of a predetermined size, a predetermined amount of water is added, and then the mixture is pulverized and mixed for about 10 to 20 hours. The mixture is dehydrated using a filter press or the like and subjected to molding.
The molding is performed in a predetermined shape by a sludge casting molding method, a pressure casting molding method, a mechanical potter's wheel molding method, a hand potter's wheel molding method, a wet press molding method, a dry press molding method, or the like. For example, in the sludge cast molding method, a predetermined amount of water and a dispersing agent are added to the dehydrated mixture, and the mixture is stirred for about 2 to 5 hours using a stirrer or the like to prepare a slurry. After pouring this slurry into a gypsum mold having a predetermined shape and making it thick, the remaining slurry is drained and demolded to obtain a molded body.
Firing is performed by drying the obtained molded body, and then firing at 1000 ° C. or more and less than 1200 ° C. using an electric furnace, a gas furnace, or the like.

Experiment No. NP204 in Table 2 The ball milling time of raw materials other than clay in the substrate was changed, and the influence of sinterability due to particle size was examined. Table 3 shows the results of measuring the average particle size of these substrates, and FIG. 2 shows the relationship between ball milling time and sinterability.

  2 and Table 3, as the pulverization time becomes longer, sintering at a slightly lower temperature proceeds, but there is no significant difference, and the influence of the particle size is small. However, in order to obtain a substrate having a wide firing temperature range and stable sinterability, it is pulverized for 12 hours or more and pulverized to an average particle diameter of 11 μm or less, preferably 10 μm or less.

  In actual sintering, since the temperature in the furnace is not uniform, if the firing temperature range is narrow, the yield of the product is deteriorated. Therefore, it is important that the firing temperature range is wide to some extent. Since the composition for low-temperature fired porcelain of the present invention has the above-mentioned composition, it has a sufficient firing temperature range of about 25 ° C. or more around 1100 ° C.

The following raw materials were used in the following examples and comparative examples.
Nepheline sianite (made by UNIMIN CANADA, nepheline sianite)
Potash feldspar (MAHAVIR MINALALS, Indian feldspar)
Petalite (Bikita Minerals, # 200 Petalite)
Clay (NZ Kaolin, New Zealand Kaolin)
These raw materials have the compositions shown in Table 1 above. In addition, the clay was removed, and wet ball milling was performed for 24 hours (only petalite was ground for 48 hours), followed by drying.

Examples 1 to 3
Nepheline sianite, potassium feldspar, petalite, and clay were mixed in a wet ball mill for 2 hours at the blending ratio shown in Table 4, and then dried. Each dried formulation was pulverized and passed through a sieve having an opening of 500 μm. The test specimen was used to press-mold a disk having a diameter of 25 mm and a thickness of about 5 mm at a pressure of 50 MPa. The test specimen for bending strength was press-molded in the same manner as a rectangular parallelepiped of 120 x 25 x about 7 mm. Each molded body was fired in an electric furnace at a heating rate of 200 ° C./h and a holding time of 1 hour at a predetermined temperature.

In order to evaluate the sinterability of the sintered body, the water absorption and bulk density of the sintered body were measured by the Archimedes method, and the method by Norris et al. (AWNorris, et al. “Range Curves: An Experimental Method for the Study of Vitreous Pottery Bodies ". Trans. J. Brit. Ceram. Soc., 78, P102-108 (1979)). The bending strength was measured by a firing three-point bending method with a distance between supporting points of 10 cm and a crosshead speed of 5 m / min. Thermal expansion was measured at a heating rate of 5 ° C / min. The crystal composition was examined by X-ray diffraction.
The maximum bulk density temperature and firing temperature range of the obtained sintered body are shown in FIG. In particular, FIG. 4 shows changes in water absorption and bulk density in Example 2, and Table 5 shows the results of measuring physical properties of Example 2 substrate.

Comparative Examples 1 to 3
Nepheline sianite, potash feldspar, and clay were mixed in a wet ball mill for 2 hours at the blending ratio shown in Table 4 and then dried. Each dried formulation was pulverized and passed through a sieve having an opening of 500 μm. The test specimen was used to press-mold a disk having a diameter of 25 mm and a thickness of about 5 mm at a pressure of 50 MPa. The molded body was fired in an electric furnace at a heating rate of 200 ° C./h and a holding time of 1 hour at a predetermined temperature.

In order to evaluate the sinterability of the obtained sintered body, the water absorption rate and bulk density of the sintered body were measured in the same manner as in Example 1 to determine the firing temperature range.
The maximum bulk density temperature and firing temperature range of the obtained sintered body are shown in FIG. Moreover, especially the change of the water absorption rate and the bulk density in the comparative example 2 is shown in FIG.

  As shown in FIG. 3, the comparative examples 1 to 3 of the nepheline sianite-potassium feldspar-clay system all have a firing temperature of 1150 ° C. to obtain the maximum bulk density temperature, but the firing temperature range is narrow. On the other hand, Examples 1-3 containing petalite have a maximum bulk density of 1100 ° C. and are sintered at a lower temperature than Comparative Examples 1-3. This is thought to be due to the mixed alkali effect due to the mixing of three alkali metals, sodium nepheline sianite, potassium potassium feldspar, and lithium lithium petalite, resulting in a decrease in the melt viscosity of the produced glass.

Moreover, if the temperature at which the water absorption rate is 0% is low, sintering is easy at low temperatures, and if the bulk density near the temperature at which the water absorption rate is 0% is stable, it can be said that the firing temperature range is wide.
As shown in FIG. 5, in the nepheline syanite-potassium feldspar-clay base material of Comparative Example 2, the water absorption becomes 0% at about 1150 ° C., but the change in bulk density is large near this temperature, and the firing temperature range is narrow. On the other hand, as shown in FIG. 4, when the nepheline syanite-potassium feldspar-petalite-clay base material of Example 2 is used, the water absorption becomes about 0% at about 1075 ° C, and the bulk density in the range of 1075 to 1150 ° C. Since it is stable, it can be seen that this temperature range (75 ° C.) is the firing temperature range and has a wide temperature range.

Therefore, by using a nepheline sianite-potassium feldspar-petalite-clay-based body, sintering at a low temperature and a wide firing temperature range that have been difficult with conventional ceramic bodies can be obtained. Compared to conventional ceramic bodies, it can be fired at a low temperature of about 100-200 ° C, and the firing temperature range is about 75 ° C. It can be fired in a fairly wide temperature range, so use a normal ceramic firing furnace. It is also easy to fire.
Further, from Table 5, it was found that the bending strength and the linear thermal expansion coefficient are equivalent to those of ordinary porcelain.

The composition for low-temperature fired porcelain of the present invention can be sintered by firing at about 1100 ° C. using inexpensive natural raw materials without blending expensive glass components such as glass frit. It is possible to cope with a rise in costs, and to contribute to the suppression of carbon dioxide emissions in the ceramic manufacturing process.
Furthermore, although the obtained porcelain is a low-temperature fired porcelain, it can obtain a dense sintered body having high mechanical strength and translucency. The composition can be suitably used not only for ornamental porcelain but also for a special porcelain used as an electronic material.

It is a figure which shows the change of the water absorption rate and the bulk density with respect to the ratio of a clay component. It is a figure which shows the relationship between ball mill grinding time and sinterability. It is a figure which shows the maximum bulk density temperature and firing temperature range in a sintered compact. It is a graph which shows the change of the water absorption rate and bulk density of the sintered body of this invention. It is a graph which shows the change of the water absorption rate and bulk density of the sintered body in a conventional product.

Claims (5)

C component which is a mineral containing Li ₂ O as a main component of an alkali metal component, A component which is a mineral containing Na ₂ O as a main component of an alkali metal component, and a mineral containing K ₂ O as a main component of an alkali metal component A non-clay component containing at least one mineral component selected from the B component, and a clay component,
30% to 50% by weight of the clay component with respect to the whole composition, and 8.3 to 75% by weight of the C component with respect to the whole non-clay component as the non-clay component. Composition. The A component is a mineral containing 5 to 22% by weight of Na ₂ O, the B component is a mineral containing 4 to 17% by weight of K ₂ O, and the C component contains 3 to 12% by weight of Li ₂ O. The composition for low-temperature fired porcelain according to claim 1, wherein the composition is a mineral. The low-temperature firing according to claim 1 or 2, wherein the composition range of the A component, the B component, and the C component as the non-clay component is represented by a hatched range of the following triangular coordinate (1). Porcelain composition.

(In the above triangular coordinate (1), the values of the vertices of each of the A, B, and C components are (100% by weight−% by weight of the clay component), and the opposite side of each vertex represents 0% by weight.)   4. The composition for low-temperature fired porcelain according to claim 3, wherein the A component is nepheline sianite or soda feldspar, the B component is potassium feldspar, and the C component is petalite. C component which is a mineral containing Li ₂ O as a main component of an alkali metal component, A component which is a mineral containing Na ₂ O as a main component of an alkali metal component, and a mineral containing K ₂ O as a main component of an alkali metal component A step of mixing a non-clay component containing at least one mineral component selected from the B component and a clay component;
Crushing each of the mixed components to an average particle size of 11 μm or less;
And a step of kneading and molding the pulverized components and firing at 1000 ° C. or more and less than 1200 ° C.

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