JPS63195157A - Manufacture of burntware - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing fired products. More specifically, it does not cause cracks or deformation, has excellent properties such as bending strength and frost damage resistance, and is extremely low cost because it uses inexpensive and easily available raw materials such as whitebait, fly ash, and blast furnace slag. The present invention relates to a method for manufacturing fired products that can be used to produce products.

[Prior Art and Problems to be Solved by the Invention] Conventionally, clay has been mainly used as a raw material for ceramic products such as tableware, roof tiles, bricks, and tiles. however,
Clay requires a large amount of water for molding, so when drying it is 5 to 8
%, and the product was prone to deformation and cracks. Therefore, relatively small items such as tableware, roof tiles, bricks, tiles, etc. can be fired by controlling the heating conditions, but large items such as panels used for the exterior walls, partition walls, floors, etc. of prefabricated houses cannot be fired. was extremely difficult. In particular, as the wall thickness increases, the drying conditions between the surface layer and the middle layer of the panel become uneven, and deformation and cracks are inevitable, making it difficult to manufacture products that can be supplied to the market in terms of strength and appearance. It was impossible.

In addition, large products require reinforcement with reinforcing bars for strength, but when clay is used, cracks occur along the reinforcing bars due to shrinkage during drying, and cracks occur in the base material due to thermal stress during firing. Because of this, it was not possible to provide reinforcement, and in this respect as well, it was considered impossible to manufacture large fired products. Of course, it was possible to manufacture large-scale products to a certain extent if mass production was not taken into account, but since the products produced were small-scale products, they would be extremely expensive.
Moreover, since it cannot be expected to be strong, it can only be used for decorative purposes such as attaching small pieces of ceramic shards to a wall that has been completed like a parapet, and is completely useless as a so-called wall material. It was impossible.

In view of the above circumstances, the inventors of the present invention have conducted extensive research over many years to provide a fired product that does not deform or crack, has excellent properties such as strength and durability, and is inexpensive. , 5I02-based heat-treated product and an alkali silicate are heated and calcined to solve the problem yA, and have completed the present invention.

[Means for solving the problems] The production method of the present invention involves molding a kneaded product consisting of a 5102 heat-treated product, an alkali silicate, and water into an appropriate shape, and producing a molded product obtained by It is characterized by heating and firing.

[Example] Hereinafter, the method for manufacturing the fired product of the present invention will be explained.

In the present invention, a 5102-based heat-treated product is used as a raw material for the fired product, but this is a broad concept that includes anything that has 5102 as its main component and has been heat-treated either naturally or artificially. Specific examples include naturally occurring materials such as anti-flinder, whitebait, volcanic ash, and feldspar powder, and artificially obtained materials such as chamotte, fly ash, blast furnace slag, bulb incineration ash, and sludge incineration ash. Since these 5TOZ heat-treated products are raw materials that have been heated once, they have the characteristics that shrinkage during drying and heating and firing of the molded product is small, and that deformation and cracks are less likely to occur in the fired product.

In particular, - in the case of large fired products, the drying state of the surface layer and middle layer becomes uneven, and deformation and cracks are likely to occur during heating and firing, but such problems occur when using 5102 series heat-treated products as raw materials. Not at all.

Among the 5iO=based heat treatment products, fly ash has the effect of preventing deformation and cracking as described above, and also has the following properties: ■ Alkaline silicates react with alumina and especially calcium oxide in fly ash to form insoluble silicates. Shikuka
(clay + Na2S102 → Na clay + Ca5IOs) is preferable because it produces a metal-like hard molded product, ■Alkali silicate acts as a melting agent during firing for fly ash, and baking can be performed at a relatively low temperature.■Fly As the ash itself is a fine powder, there is no need to pulverize it for compounding, and fly ash, which is currently a problem in waste disposal, can be used effectively. It has advantages.

In the present invention, an alkali silicate is used as a raw material for the fired body together with the 5i02 heat-treated product. Examples of the alkali silicates include sodium silicate, potassium silicate, and lithium silicate, and these can be used in either liquid or powder form. These alkali silicates are used as molding and solidifying agents for 5102 heat-treated products;
Used as a sintering agent. When fly ash is used as the 5102 heat-treated product, it reacts with alumina and calcium oxide in the fly ash to form a hard molded product. This molded product can be cured and removed from the mold within 60 minutes, and can be dried as well as removed from the mold without the need for curing. This is an advantage not found in cement products or clay moldings, and is a key to increasing productivity. Furthermore, since it functions as a melting agent for fly ash during firing, it has the advantage of being able to be fired at a relatively low temperature.

Among the silicic acid compounds, potassium silicate reacts well with the glaze,
The beauty of the glazed surface of the fired product is not impaired.

Alkali silicates may be used alone or in combination of two or more.

The usage ff1 (if two or more types are used, the total usage ff1) is preferably 3 to 35% (weight %, the same applies hereinafter) of the kneaded material, and more preferably 5 to 30%. If the amount used is less than 3%, there is a problem that the molded product will not solidify to a strength that allows handling. On the other hand, if the amount used exceeds 35%, the curing time will be too long (the glaze will remain agar-like (jelly-like) and will not harden), and alkali will precipitate on the surface, impairing the beauty of the glaze and causing efflorescence after firing. There is a problem.

In addition, it is disclosed in Japanese Patent Application Laid-Open No. 57-1999 that fly ash, which is a type of 8102 heat-treated product, is kneaded with sodium silicate, molded, cured, and dried to obtain a hard molded product.
No. 204278. However, this molded product is produced by simply curing and drying the kneaded product, and is not heated and fired, so its physical properties such as bending strength, surface hardness, and frost damage resistance are significantly inferior. Therefore, it has a defect that it cannot be used for applications requiring strength such as wall materials and floor materials. In this regard, since the fired product obtained by the production method of the present invention is a sintered product, it has high physical properties such as bending strength, surface hardness, and frost damage resistance, and can be used for various purposes.

In the present invention, wollastonite may be added to the kneaded material consisting of the 5i02 heat-treated product, alkali silicate, and water. The following effects can be achieved by adding wollastonite.

■Since wollastonite is a acicular crystalline mineral, it has low drying shrinkage and excellent dimensional stability. Therefore, cracks are less likely to occur during drying and heating and baking, and dimensional accuracy can be significantly improved.

■Wollastonite has a small coefficient of thermal expansion and can be fired quickly, alleviating thermal stress and preventing deformation and cracking.

■ Adding wollastonite reduces firing shrinkage, making it difficult for cracks to occur. In particular, if reinforcing bars are buried, thermal stress at high temperatures can be controlled, making it even more difficult for cracks to occur.

■Since wollastonite is a acicular crystalline mineral, the elastic modulus of fired products is improved.

The amount of wollastonite used is preferably 5 to 25% of the kneaded material. If the amount used is less than 5%, the above properties of wollastonite will not be reflected in the physical properties of the fired product, while if the amount used exceeds 25%, the amount of water added will increase, resulting in large drying shrinkage, and Adding more wollastonite is not preferable because there is no change in the effect. However, if 20% or more is required, the disadvantage of drying shrinkage can be eliminated by calcining at a temperature of too much degree Celsius.

In the present invention, glass powder may be further added to the kneaded material. In this case, the glass powder is used as a fluxing agent and does not have the function of a solidifying agent. The amount to be used is not particularly limited and may be appropriately selected in consideration of the amount of water glass added and the like. Typically,
Although the amount of sodium silicate and/or potassium silicate used is reduced to the hardening limit, it is preferable to increase the amount of glass powder used as a flux to suppress surface precipitation. Furthermore, when setting the firing temperature, it is preferable to increase the amount of glass powder used if low-temperature firing is desired.

In addition, aggregates such as feldspar, chamotte, foamed shale, foamed refractory rock, and foamed clay may be added to the kneaded material, if necessary.

In the present invention, in order to impart the desired appearance, durability, and water resistance to the fired product, the surface of the molded product may be glazed or coated with engobe prior to heating and firing, or may be configured to do both. As the glaze, a suitable glaze such as a frit glaze or a raw glaze can be used, and the amount applied is not particularly limited. Furthermore, the coating method can be any of the commonly used methods such as spraying, pouring, and brushing. As the engobe, for example, white clay, feldspar, kaolin, a combination of these and clay, etc. may be used, but it is not limited to these. For example, 35% white clay, 3% white clay (1000℃ calcined)
A mixture consisting of 5% glass powder, 25% glass powder, and 35% F220 is ground in a bot mill, CMC liquid is added to form a slurry, and the slurry is sprayed. When it is fired at 1050°C, a semi-matte reddish-brown surface is formed.

The method for producing a fired product of the present invention consists of molding a kneaded product consisting of the aforementioned 5i02 heat-treated product, an alkali silicate, and water, and heating and firing the resulting molded product. Each step will be explained in order below.

First, all the ingredients are mixed at the same time and stirred with a mixer to obtain a kneaded product. Next, the obtained kneaded material is poured into a mold of an appropriate shape. In this case, if the fired product requires reinforcement, reinforcing materials such as reinforcing bars or wire mesh are placed in advance in the mold. Usually, demolding is performed after the kneaded material has been cured for 30 to 60 minutes.

After demolding, the molded body is dried by hot air, far infrared heating, microwave heating, etc. Drying may be performed at room temperature. The time required for one drying cycle varies depending on the thickness of the molded product and the heat dehydration method, but is approximately 30 minutes to 8 hours. In short, it is preferable to perform rapid drying so that the moisture content is approximately 2% or less.

After drying, the molded body is placed in a firing furnace and heated to a temperature of 980 to 1050.
Heat and bake at ℃ for about 4 to 6 hours. The heating temperature and heating time may be selected in consideration of the type of raw materials, the blending ratio, the dimensions of the molded body, and the like.

Regarding the heating speed, especially in the case of fly ash, it is important to completely burn out the contained unburned coal fine particles before the glaze melts, and it is necessary to maintain the temperature range of 500 to 700°C for a certain period of time.

Next, the manufacturing method of the present invention will be explained based on Examples, but the present invention is not limited to these Examples.

Examples 1 to 4 Mixtures with the proportions shown in Table 1 were mixed simultaneously in a mixer for about
A kneaded product was obtained by stirring for a minute. The obtained kneaded material was poured into a wooden mold to form test specimens having the dimensions shown in Table 1. After the kneaded product was left to stand for 60 minutes to harden, it was removed from the mold, and then dried by microwave heating for 25 minutes. After drying, heating and baking were performed in a roller kiln under the conditions shown in Table 1. The relationship between firing time and firing temperature in Example 1 is shown in FIG. After heating and baking, let it cool naturally, Example 1
-2 was taken out of the kiln after 15 hours, and Examples 3 and 4 were taken out of the kiln after 5 hours. In the Examples and Comparative Examples herein, three test specimens were each manufactured, and the various physical property data described below are, in principle, the average value of the measured values of the three test specimens.

The total shrinkage rate (JISA5209
(based on JIS A3209), 24-hour water absorption rate (based on JIS A3209),
Bulk specific gravity and bending strength (based on JIS A3209) were measured. The measurement results are shown in Table 2.

Comparative Example 1 Test specimens were produced by heating and firing the compositions shown in Table 1 in the same manner as in Examples 1 to 4, except that the heating and firing conditions were changed to those shown in Table 1.

Comparative Example 2 A test specimen was produced in the same manner as in Example 1, except that the same weight of clay was used instead of fly ash.

The same items as in Examples 1 to 4 were measured for the test specimens obtained in Comparative Examples 1 to 2. The measurement results are shown in Table 2.

Example 5 A test specimen was produced in the same manner as in Example 1, except that the blending ratio and heating and firing conditions were as shown in Table 1.

Freezing damage resistance (AST) IC68 for the obtained test specimen
B), bending strength (based on JIS A3209), and surface hardness (based on JIS K 7204) were measured. The results are shown in Table 3.

Comparative Example 3 A test specimen was produced in the same manner as in Example 5, except that heating and baking were not performed. The same items as in Example 5 were measured for the obtained test specimen. The results are shown in Table 3.

[Left below] Table 3 * (Conditions) Number of rotations: 1000 rpm Load rotation type
iooog Mixtures with composition ratios shown in Table 4 are mixed at the same time in a mixer for about 3
A kneaded product was obtained by stirring for a minute. The obtained kneaded material was poured into a wooden mold to form test specimens having the dimensions shown in Table 4.

After being left to harden for 2 hours, the mold was demolded and then dried by microwave heating for 25 minutes. After drying, heating and baking were performed in a roller kiln under the conditions shown in Table 4. After heating and firing, it was allowed to cool naturally, and after 6 hours, it was taken out of the kiln. The bending strength (based on JISA5209) of the obtained test specimen was measured. In addition, the shrinkage rate after the drying process (JIS A320
9) was also measured. The results are shown in Table 4.

Comparative Examples 4 to 6 Except for changing the blending ratio of the kneaded material as shown in Table 4,
Test specimens were manufactured in the same manner as in Examples 6 to IO. The same items as in Examples 6 to 0 were measured for the obtained test specimens. The results are shown in Table 4.

[Margins below] Table 4 [Evaluation Observation] Desk Curing time o: Within 2 hours Δ: Not cured sufficiently in 2 hours ×: Not cured at all in 2 hours *2 Shrinkage O: 1 due to shrinkage due to drying Within .5% From Comparative Example 2, SiO was used as the base material of the fired product.
It can be seen that when the two-system heat-treated product is used, the total shrinkage rate becomes extremely small and the bending strength is significantly improved. Regarding the appearance, almost no cracks or deformations were observed in the test specimens of Examples 1 to 4 (visual observation), but many cracks and deformations were observed in the test specimen of Comparative Example 2.

Furthermore, from Examples 1 to 4 and Comparative Example 1, when glass powder is used as the base material instead of the 8102 heat-treated product, the total shrinkage rate is extremely small, but the bending strength is extremely low, making it suitable for construction panels etc. It can be seen that it cannot be put to practical use.

Next, it can be seen from Example 5 and Comparative Example 3 that the frost damage resistance, bending strength, and surface hardness are significantly improved by heating and baking.

Furthermore, from Examples 6 to 10 and Comparative Examples 4 to 6, the preferred usage range of alkali silicate (water glass) is 3 to 35% in the total kneaded material, and the more preferred usage range is also 5 to 30%. %It can be seen that it is.

[Effects of the Invention] As described above, the method for producing a fired product of the present invention uses a 5io2 heat-treated product that has been heated once as a raw material, so the shrinkage of the molded product during drying and heating and firing is small. This material has the excellent effect of preventing deformation cracks from occurring in fired products. As a result, it has become possible to manufacture large-sized products that were previously thought to be completely impossible in practical terms, breaking through the limitations of conventional fired products and using groundbreaking new technology to preserve that image. be. In addition,
According to the manufacturing method of the present invention, fly ash, blast furnace slag, etc., which have traditionally been largely discarded, can be effectively utilized, extending the service life of treatment plants and reducing treatment costs. The ripple effects, such as making it unnecessary, are extremely large.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the relationship between firing time and firing temperature when firing the test specimen according to Example 1. Patent applicant National Housing Industry Co., Ltd. and 2 others

Claims (1)

[Claims] 1. SiO_2-based heat treatment product, alkali silicate,
A method for producing a fired product, which comprises molding a kneaded product with water into an appropriate shape and heating and firing the resulting molded body. 2. The manufacturing method according to claim 1, wherein the molded body is coated with engraving and/or glazed and then heated and fired. 3. The manufacturing method according to claim 1 or 2, wherein the kneaded material further contains wollastonite. 4. The manufacturing method according to claim 1, 2, or 3, wherein the kneaded material further contains glass powder.