JP2008001564A - A method for producing a porous ceramic fired body. - Google Patents

Abstract

Provided is a porous ceramic fired body having improved water retention performance of a porous ceramic fired body, for example, having a high water absorption rate suitable for heat island countermeasures, a high water absorption rate, and a slow water discharge rate.
A porous ceramic fired body containing a fired product of weathered volcanic ash and fired vermiculite and having an open porosity of 17% or more. The fired body has high water absorption performance and water retention performance, has the performance of gradually releasing the retained water over a long period of time, and is relatively inexpensive and supplies a large amount stably. It is something that can be done.
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Description

  The present invention relates to a fired porous ceramic body and a method for producing the same, and in particular, has a high water absorption rate and a high water absorption rate, and also has a sustained release property for water that has been absorbed or retained once, TECHNICAL FIELD The present invention relates to a porous ceramic fired body useful as a body and a method for producing the same.

Porous ceramic fired bodies are widely used in various fields as ceramic porous bodies, for example, as structural materials, filters, biomaterials, catalyst carriers, refractory materials, heat insulating materials, soundproof materials, and the like. However, most ceramic porous bodies are manufactured through a firing process and generally have low water retention and moisture release properties.
Weathered volcanic ash such as Kanuma soil, Osawa soil and colloidal soil is used as horticultural soil in the form of granules by utilizing the water retention capability of allophane contained therein. Allophane is a hydrous aluminum silicate, and is composed of hollow particles having an outer diameter of 30 to 50 angstroms and pores through which water molecules can enter and exit. Allophane is mixed with a setting and curing agent such as mortar, gypsum, slaked lime, dolomite, etc., and if necessary, water is further added and kneaded, and the kneaded product is extruded and cured and cured, or a humidity control building material, or Moisture-conditioning building materials with water retention and moisture releasing properties obtained by mixing allophene with other ceramic raw materials such as Kibushi clay, Kazume clay, silica stone, porcelain stone, press molding and firing are known. (See Patent Document 1).
Vermiculite is used for horticultural soil, heat insulating materials and the like by utilizing the property of expanding by heat treatment or chemical treatment. In addition, in building materials compositions in which unexpanded vermiculite is blended with hydraulic materials such as gypsum, cement, calcium silicate, slag gypsum, etc. that have hygroscopicity but insufficient moisture release, further expandable vermiculite is blended and released. A building material composition with improved wet ability is known (see Patent Document 2).
JP-A-8-144387 JP 2003-146719 A

  Conventionally, in the porous ceramic fired body produced through the firing step, the surface of the pores present therein is composed of an inert substance having poor reactivity. Therefore, in the case of a porous ceramic fired body with a large porosity, moisture is absorbed into the pores, so that the water absorption capacity is increased, but under dry conditions, the absorbed moisture is quickly released. Will be. In particular, foamed ceramics obtained by molding and firing glass powder have a high porosity, and therefore a very high water absorption rate is obtained. However, since the pores are connected to the outside through a narrow passage like an ink bottle, the water discharge speed is high for a low water absorption speed, and high water retention performance cannot be obtained.

  Weathered volcanic ash is present in large quantities as pumice or clay, and contains hollow spherical nanoparticles allophane and imogolite, and is excellent in sinterability and water retention at low temperatures. However, weathered volcanic ash is only partially used as a ceramic material, and recently, development of humidity control building materials and other new applications has begun. In addition, vermiculite present in large quantities has a plate-like form and becomes porous by heat treatment and chemical treatment, and has a shielding action against the permeation of fluid because it is plate-like. And it has a function to improve the strength when it is combined with other particles and fired, but only a part is used as a building material such as a heat insulating material or a sound insulating material, and development of a new application is desired. ing.

Further, for example, as one of the measures for avoiding the heat island phenomenon, a material having a high water absorption rate, a large water absorption rate, and a low moisture release rate is desired.
The present invention has a high water absorption rate, a high water absorption rate, and a low moisture release rate, and is relatively inexpensive and suitable for heat island countermeasures, for example, a filler material for water retention asphalt pavement. It aims at providing the ceramic material which can be used as a pavement block material and a water retention building material.
In order to obtain a porous ceramic material having a high water absorption rate, a large water absorption rate, and a low moisture release rate, the inventors have improved the water retention performance of the porous ceramic fired body. Considering the nature of the weathered volcanic ash and vermiculite, in particular, the raw materials used in the production of the porous ceramic fired body are considered. The relationship between the microstructures was investigated and the present invention was reached.

  Further, the present inventors can produce a porous ceramic fired body by mixing weathered volcanic ash and vermiculite powder in a powder form or a paste form, drying and firing, and the porous body obtained thereby Ceramic fired bodies have pores that retain moisture and are water-retaining, for example, allophane particles and vermiculite particles used as raw materials, so that the water release rate is high despite the high water absorption rate and high water absorption rate. It has been found that the speed is slow and the water retention function is excellent.

The present invention improves the water retention performance of a porous ceramic fired body, for example, to provide a ceramic porous body having a high water absorption rate suitable for heat island countermeasures, a high water absorption rate, and a slow water discharge rate. It is aimed.
That is, the present invention is a porous ceramic fired body containing a fired product of weathered volcanic ash and fired vermiculite and having a porosity of 17% or more, and The present invention is a fired porous ceramics characterized in that it is a fired body containing a calcined product of weathered volcanic ash, calcined vermiculite, and calcined waste glass powder and having an open porosity of 17% or more. Further, the present invention is a calcined body containing 30 to 90 parts by mass of a calcined product of weathered volcanic ash and 10 to 70 parts by mass of calcined vermiculite and having an open porosity of 17% or more. There is a porous ceramic fired body characterized in that, furthermore, the present invention comprises 50 to 80 parts by mass of a calcined product of weathered volcanic ash, 10 parts by mass of calcined vermiculite, It made that contained a 10 to 40 parts by weight of waste glass powder, in the porous ceramic sintered body which is a sintered body having an open porosity of 17% or more. In addition to these, the present invention molds a mixture of weathered volcanic ash and vermiculite, and heats the molded article at a temperature of 500 to 1000 ° C. to have a porosity of 17% or more. There is a method for producing a porous ceramic fired body characterized by producing a fired body, and the present invention forms a mixture of weathered volcanic ash, vermiculite, and waste glass powder. A method for producing a porous ceramic fired body, characterized by producing a porous ceramic fired body having an open porosity of 17% or more by heating at a temperature of 1 to 1000 ° C. A mixture containing 30 to 90 parts by mass of weathered volcanic ash and 10 to 70 parts by mass of vermiculite was molded, and the molded product was heated to a temperature of 500 to 1000 ° C. There is provided a method for producing a porous ceramic fired body characterized by heating to produce a porous ceramic fired body having an open porosity of 17% or more. In addition, the present invention relates to 50 to 50 of weathered volcanic ash. A mixture containing 80 parts by mass, 10 parts by mass of vermiculite, and 10 to 40 parts by mass of waste glass powder was molded, and the molded product was heated at a temperature of 500 to 1000 ° C. to obtain an opening of 17% or more. A method for producing a porous ceramic fired body comprising producing a porous ceramic fired body having a porosity.

In the fired body of the present invention, the fired vermiculite may include a part of the fired mica or talc or a mixture thereof in a smaller amount than the vermiculite. In the present invention, the fired body further contains a foamed glass powder fired product, a glass fiber fired product, a sepiolite fired product, a cement powder fired product, an organic powder fired product, or a mixture of these two or more fired products. can do. Further, in the fired body of the present invention and the method for producing the same, the mixture of weathered volcanic ash and vermiculite may further include foamed glass powder, water glass, glass fiber, sepiolite, cement powder or organic powder, or a mixture of two or more thereof. It can be contained.
In the method for producing a fired body of the present invention, the raw material vermiculite may contain a smaller amount of mica or talc or a mixture thereof than a part of the vermiculite, and a part of the vermiculite than the vermiculite. A small amount of mica or talc or a mixture thereof can be substituted. In the method for producing a fired body of the present invention, the vermiculite can be fired vermiculite, unfired vermiculite, or a mixture thereof.

  The porous ceramic fired body of the present invention contains, for example, 30 to 90 parts by weight of a calcined product of weathered volcanic ash and 10 to 70 parts by weight of calcined vermiculite, mica or talc, or a mixture of two or more thereof. It has an open porosity of 17% or more, and is produced from raw weathered volcanic ash and a large amount of vermiculite, mica, talc, or a mixture of two or more thereof. The porous ceramic fired body of the present invention is approximately 1.1, is lightweight, has a large water absorption performance and water retention performance, and gradually releases the retained water over a long period of time. That is, it has sustained release properties, can be supplied in a relatively large amount at a relatively low cost. Therefore, the porous ceramic fired body of the present invention can be used, for example, as a water retention material for heat island countermeasures, as a water retention asphalt pavement filler material, a pavement block material, and a water retention building material such as a roof material and an outer wall material. As a result, the use of weathered volcanic ash and vermiculite can be expanded.

The fired porous ceramic body of the present invention is a fired body containing a fired product of weathered volcanic ash and fired vermiculite and having an open porosity of 17% or more. In the present invention, the porous ceramic fired body is obtained by mixing weathered volcanic ash and vermiculite, for example, in a powder state by a dry method, or by mixing, for example, in a paste form by a wet method, drying, and firing after molding. Can be manufactured. In the present invention, a part of vermiculite can be used as a raw material by substituting a part thereof with mica or talc or a mixture of mica and talc.
In the present invention, weathered volcanic ash includes allophane and / or imogolite which are hollow and spherical nanoparticles therein and has sinterability at a relatively low temperature, regardless of the origin. It can be used. On the other hand, as long as the vermiculite has a property of expanding at a temperature of 900 ° C. or lower, magnesium vermiculite, potassium vermiculite, and other vermiculites can be used. However, a vermiculite having a property of expanding at a temperature of 800 ° C. or lower, more preferably 500 ° C. or lower, is preferable because vermiculite can be expanded at a relatively low temperature.

  In this invention, mixing of weathered volcanic ash and vermiculite can be performed in the mixed state of a granular material or a powdery material, or a granular material and a powdery material. However, it is preferable to mix the raw weathered volcanic ash and vermiculite in the form of a paste or slurry in the presence of water, alcohol or an organic solvent, because generation of dust can be avoided. The particle sizes of weathered volcanic ash and vermiculite may be powders or granules that have passed through a sieve having, for example, 5 mm or less, that is, an opening of 5 mm or less. In the present invention, for example, weathered volcanic ash and vermiculite are mixed within a period of 3 hours. + Mixing of weathered volcanic ash and vermiculite can be performed by a mixing apparatus such as a container rotating mixer, and can also be performed by a ball mill or a rod mill. Using a ball mill or a rod mill for mixing weathered volcanic ash and vermiculite, mixing for 30 minutes or more is preferable because the weathered volcanic ash and vermiculite are pulverized and mixed uniformly in the mixing process. . Such a pulverization step in the present invention is carried out for the purpose of mixing vermiculite and weathered volcanic ash powders and pulverizing vermiculite particles to suppress expansibility. It is preferable to reduce the size of the material since the expandability is reduced and the shape of the fired body can be maintained. The mixing ratio of weathered volcanic ash and vermiculite is, for example, 10 to 90% by mass of weathered volcanic ash and 10 to 90% by mass of vermiculite, and both are mixed to 100% by mass.

In the present invention, the mass ratio of the mixture of weathered volcanic ash containing allophane and vermiculite is not particularly limited, but is preferably 5: 5 to 9: 1. When the mixing ratio of weathered volcanic ash such as volcanic ash pumice containing allophane is small, the sinterability is lowered, and the water absorption rate of the resulting ceramic porous body is unfavorable. On the other hand, if the amount is large, firing shrinkage becomes large, and the sustained release property is lowered, which is not preferable. Deformation and cracking of the molded product due to expansion of vermiculite during firing of the mixed molded product of weathered volcanic ash and vermiculite can be suppressed by grinding the unfired vermiculite finely, for example, to a particle size of 0.25 mm or less. . When vermiculite that has been fired is used as the raw material vermiculite, the occurrence of cracks can be suppressed, and deformation of the fired body can be reduced.
In the present invention, the weathered volcanic ash containing allophane and vermiculite, or the weathered volcanic ash containing allophane and vermiculite, mica, talc, or a mixture of two or more thereof are pulverized simultaneously with the mixing of a ball mill or the like. It is preferred to use a mixer that can.

Vermiculite is obtained in a state where the particle diameter is larger than that of weathered volcanic ash such as allophane, and further, due to heating, the particle size of the mixture of weathered volcanic ash such as vermiculite and allophane is 0.25 mm or less, for example. It is preferable to make it smaller. A particle size of a mixture of weathered volcanic ash such as vermiculite and allophane is preferably 0.25 mm or less, for example, because it is easy to mold and deformation of the molded product due to expansion of vermiculite during firing can be suppressed. Therefore, in the present invention, for example, the mixture is pulverized for 30 minutes or more by a mixing and pulverizing machine such as a ball mill to obtain a particle size of 0.25 mm or less, for example.
The mixture of weathered volcanic ash obtained by mixing and vermiculite has an appropriate shape, for example, a columnar shape, a spherical shape, a hollow cylindrical shape, a spheroid shape, a cubic shape, a rectangular parallelepiped shape, or other appropriate shaped particles, It can shape | mold into molded objects, such as a granule or a lump. For molding, a molding method such as a dry uniaxial molding method using a pressing die, a method of extruding a paste, and a method of pouring can be used.

  A molded body of a mixture of weathered volcanic ash and vermiculite is heated at a temperature of 500 to 1000 ° C. for 1 to 5 hours. In order to produce a ceramic porous body having a high open porosity, it is necessary to increase the mixing ratio of allophane, and the higher the mixing ratio of allophane, the higher the open porosity. Therefore, in order to increase the open porosity, it is necessary to increase the mixing ratio of weathered volcanic ash containing allophane, for example, Kanuma soil, and to increase the mixing ratio of weathered volcanic ash, such as Kanuma soil, for example. As a result, the open porosity can be increased. In order to maintain a high open porosity, it is desirable to calcinate while avoiding sintering. The calcining temperature of a molded body of weathered volcanic ash and vermiculite, mica, talc, or a mixture of two or more thereof is 800 ° C. or less. Baking at a temperature is preferred. Vermiculite, mica, talc, or a mixture of two or more of these is preferable because the occurrence of cracks in the firing step can be prevented by firing in advance. Any kind of firing can be used as long as it is a commonly used firing furnace.

  The use of the ceramic fired body of the present invention is not particularly limited, but is lightweight and has a sustained release property with respect to moisture. For example, as a water retention material for heat island, a pavement or a pavement block It can be used for water-retaining materials such as roofing materials and roofing materials.

Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to the contents of the illustration and description.
Example 1
In this example, a porous ceramic fired body was prepared from a raw material mixture of weathered volcanic ash containing allophane and vermiculite in various mixing ratios.
In this example, commercially available Kanuma soil for horticulture was used as a raw material for weathered volcanic ash containing allophane, and unburned vermiculite (manufactured by Vermitec) was used as vermiculite.
7 mass parts of horticultural kanuma soil having a particle size of 0.25 mm or less that passed through a sieve of 0.25 mm sieve, and also passed through a sieve of 0.25 mm sieve, that is, unfired with a particle size of 0.25 mm or less 3 parts by mass of vermiculite was mixed, put in a ball mill and mixed for 1 hour to obtain a mixed powder. The obtained mixed powder was molded into a cylinder having a diameter of 10 mm and a thickness of 5 mm using a stainless steel mold. The obtained molded body was put into an electric furnace, and the temperature was increased at a rate of temperature increase of 10 ° C./min, and the product was fired at a firing temperature of 800 ° C. for 1 hour. The open porosity of the obtained 800 ° C. fired body was 17 to 67%. The open porosity is the same as the water absorption rate.
In this example, the open porosity of the porous ceramic fired body is 0.01 to 1000 μm using mercury intrusion type mercury porosimeter (manufactured by C.E Instrument Co.) Pascal 140 and Pascal 240. Range was measured. The open pores of the fired body of Example 2 had a distribution having a peak center at 1 μm and extending to 0.1 to 10 μm. When the mixing ratio of vermiculite was increased, for example, the open pores of the fired body of Example 1 had a distribution having a peak center at 20 μm in addition to 1 μm and extending to 10 to 100 μm. As the amount of allophane increased, the number of pores smaller than 0.1 μm also increased.
Hereinafter, various mixed powders were produced by changing the mass ratio of horticultural kanuma soil to unburned vermiculite (garden kanuma soil / unfired vermiculite), and the manufactured mixed powder was made using a stainless steel mold. Then, after forming into a cylinder having a diameter of 10 mm and a thickness of 5 mm by a dry method, and drying the obtained molded body at room temperature, the temperature was increased at a heating rate of 10 ° C./min, and a firing temperature of 800 ° C. Baked for 1 hour. About the obtained porous ceramic fired body, the time (time) and compressive strength at which the water absorption rate and the water content rate become 50% of the water absorption rate were measured.
In this example, an example of a mixed powder having a mass ratio of horticultural kanuma soil / unfired vermiculite is 8/2, and Example 1 is an example of a mixed powder having a horticultural kanuma soil / unfired vermiculite mass ratio of 9/1. Was taken as Example 2. Reference Example 1 is an example of only unburned vermiculite (massage kanuma soil / unfired vermiculite mass ratio is 0/10), and Reference Example 2 is an example of only horticultural kanuma soil (horticultural kanuma soil / not yet). The mass ratio of calcined vermiculite is 10/0).
The results are shown in Table 1 below.

  In the column of the mixing ratio in Table 1, A indicates the mass part of horticultural kanuma soil in the mixed powder, and B indicates the mass part of unfired vermiculite in the mixed powder. The formation of open porosity became higher as the mixing ratio of horticultural kanuma soil was higher than that of unfired vermiculite.

In the case of the fired product of vermiculite of Reference Example 1, since the particle size is relatively large, it is difficult to form as compared with the raw material mixture of the present invention, and the amount of expansion during firing is large. Not practical as a body.
Further, regarding the “time for the moisture content to reach 50% of the water absorption rate” indicating the degree of release of the moisture content of the fired body, in the case of the unfired vermiculite of Reference Example 1, it was 18.8 hours. On the other hand, in Example 1 of the porous ceramic fired body of the present invention, it is 29 hours, and in Example 2 of the present invention, it is 31 hours, and the release time of the water-containing moisture is the same as in the case of unfired vermiculite. Compared to Reference Example 1, the example of the porous ceramic fired body of the present invention is excellent in sustained release, being 1.6 to 1.7 times. Similarly, in the case of the horticultural kanuma soil of Reference Example 2, the “time for the water content to reach 50% of the water absorption” indicating the degree of release of water content is 20.4 hours. In Example 1 of the invention, it is 29 hours, and in Example 2 of the present invention, it is 31 hours, and the release time of the water content is 1.4 to 1. It is 5 times, and both Examples 1 and 2 of the fired porous ceramic body of the present invention are excellent in sustained release properties as compared with Reference Example 2.
This indicates that the sustained release property of the fired porous ceramic body of Example 1 of the present invention cannot be obtained only by the fired body of Kanuma soil for horticulture and only by unburned vermiculite. .
In this example, the “time (time) for the moisture content to reach 50% of the water absorption rate” in Table 1 is a value measured in an environment at room temperature of 20 ° C. and relative humidity of 55%. This value in this example indicates that the porous ceramic fired body in this example releases moisture by maintaining a moisture content of 50% or more of water absorption for 29 hours or more in an environment of room temperature at 20 ° C. and 55% relative humidity. This indicates that it has a sustained release capability.
In this example, the specific gravity of the porous ceramic fired body of Example 1 was 1.13, and the specific gravity of the porous ceramic fired body of Example 2 was 1.08, both of which were lightweight. The specific gravity of the fired body of Reference Example 2 was 0.94.
Example 2

In this example, as in Example 1, commercially available horticultural kanuma earth was used as a raw material for weathered volcanic ash containing allophane, and unburned vermiculite (manufactured by Vermitech) was used as vermiculite.
In this example, a raw material mixture having a mass ratio of Kanuma soil for gardening / unfired vermiculite of 9/1 is calcined at 600 ° C., 700 ° C., 750 ° C., or 800 ° C. This is an example in which a porous ceramic fired body was prepared by firing at different temperatures and firing temperatures. The porous ceramic fired body obtained at each firing temperature was measured for moisture content, time for the moisture content to reach 50% of the water absorption rate, and compressive strength.
In this example, 9 parts by weight of Kanuma soil having a particle size of 0.25 mm or less is mixed with 1 part by weight of unfired vermiculite having a particle size of 0.25 mm or less, and the mixture is placed in a ball mill for 1 hour to obtain a mixed powder. It was. The obtained mixed powder was molded into a cylinder having a diameter of 10 mm and a thickness of 5 mm using a stainless steel mold. The obtained molded body was put into an electric furnace, and the temperature was gradually raised. For example, the temperature was raised at a temperature rising rate of 10 ° C./min, and firing was performed at a firing temperature for 2 hours.
As a product of the comparative example, a foamed glass fired body obtained by molding only waste glass powder as a raw material and firing the molded product at 900 ° C. was used. The fired glass foam of this comparative example showed a water absorption rate comparable to that of the fired porous ceramic body of this example. However, the product of this comparative example absorbed only about 50% of the water absorption even after 10 minutes, and it took 24 hours or more to reach the water absorption.
Table 2 shows the results of measuring the water absorption rate, the time for the moisture content to reach 50% of the water absorption rate, and the compressive strength of the porous ceramic fired body of this example and the foamed glass fired body of the comparative example.

In Table 2, “Time (time) for the moisture content to reach 50% of the maximum water absorption” is a value measured in an environment at room temperature of 20 ° C. and a relative humidity of 55%. This value in this example indicates that the porous ceramic fired body of this example releases moisture by maintaining a moisture content of 50% or more of water absorption for 30 hours or more in an environment of room temperature of 20 ° C. and 55% relative humidity. This indicates that it has a sustained release capability.
In the case of the foamed glass fired product of the comparative example, the water absorption is as high as 44%, but the “time for the water content to reach 50% of the water absorption” indicating the degree of release of the water content is extremely short, 3.9 hours. It's time. Therefore, the release time of the water content is 7.4 times that of the comparative example in the case of Example 1, and 7.9 times that of the comparative example in the case of Example 2. is there. Therefore, Examples 1 and 2 of the porous ceramic fired body of the present invention both show that the sustained release property is remarkably superior to the comparative example.

In the porous ceramic fired body in this example, the time to reach 90% of the water absorption rate was as short as 1 minute or less. On the other hand, in the foamed glass fired product of the comparative example, the time to reach 90% of the water absorption rate is as long as 24 hours, and the water absorption speeds of both products are very different. This seems to be due to the fact that there is a large difference in the shape of the pores between the two products, and the size of the pore diameter of the communicating portion is different.
The water absorption rate of the porous ceramic fired body in this example showed a high water absorption rate of 40% or more even when the firing temperature was 800 ° C. when the Kanuma soil content was 60% by mass or more. In the case of the same Kanuma soil content, the water absorption rate of the product obtained by firing at a firing temperature of 700 ° C. was about 10% higher than that of the 800 ° C. fired product.
Example 3

This example is an example of preparing a porous ceramic fired body for a raw material mixture obtained by mixing weathered volcanic ash containing allophane, vermiculite, and waste glass powder at various mixing ratios.
In this example, as a raw material of the fired porous ceramic body, commercially available horticultural kanuma soil is used as a raw material of weathered volcanic ash containing allophane, calcined vermiculite (manufactured by Vermitech) is used as vermiculite, and waste glass powder As a waste glass powder obtained by pulverizing colorless glazed glass waste.
A raw material mixture prepared by mixing garden kanuma earth, calcined vermiculite, and waste glass powder at various mixing ratios was mixed for 30 minutes with a ball mill to obtain a mixed powder. The obtained mixed powder was molded by a dry method into a cylinder having a diameter of 10 mm and a thickness of 5 mm using a stainless steel mold. The obtained molded body was fired at 800 ° C. for 1 hour in an electric furnace.
In this example, an example of a raw material mixture having a mixed mass ratio of horticultural kanuma soil / fired vermiculite / waste glass powder to 2/1/7 is Example 3, and the mass of horticultural kanuma soil / fired vermiculite / waste glass powder. Example of raw material mixture with ratio of 4.5 / 1 / 4.5 is Example 4, and example of raw material mixture with mass ratio of garden kanuma soil / unfired vermiculite / waste glass powder is 7/1/2 Example 5 was adopted. About the obtained porous ceramic fired body, the time (time) for the water absorption (%) and the water content to reach 50% of the water absorption was measured. The results are shown in Table 3 below.

In these examples, the formation of open porosity increased as the mixing ratio of horticultural kanuma soil increased.
The open porosity of the obtained 800 degreeC sintered body is 17-67%, and it becomes so large that the mixing ratio of Kanuma soil is high.
In the mixing ratio of Table 3, A shows the mass part of the horticultural kanuma soil in the mixed powder, B shows the mass part of unfired vermiculite in the mixed powder, and C shows the mass part of the waste glass powder.
In Table 3, “Time (time) for water content to reach 50% of water absorption” is a value measured in an environment at room temperature of 20 ° C. and relative humidity of 55%. This value in Example 5 indicates that the porous ceramic fired body of this example maintains a moisture content of 50% or more of the water absorption rate for 32 hours or more in an environment at a room temperature of 20 ° C. and a relative humidity of 55%. It shows that it has a sustained release property that can be released.
Example 4

In this example, a porous ceramic fired body was prepared by varying the firing temperature for the raw material mixture having a mass ratio of 7/1/2 of garden kanuma earth / unfired vermiculite / waste glass powder used in Example 3. And the open porosity was measured about the porous ceramic fired body obtained at each firing temperature. In this example, it was found that firing at a firing temperature of 700 ° C. or lower is desirable to maintain a high open porosity. When unsintered vermiculite is used, many cracks are generated in the sample because the expansion rate due to firing is too large. By mixing for 30 minutes or more and reducing the particle size of the vermiculite, the porous ceramics It was found that generation and deformation of cracks in the fired body can be prevented. In addition, it was found that by using vermiculite that has been fired in advance as the vermiculite, the generation and deformation of cracks in the porous ceramic fired body can be suppressed.
In this example, the porous ceramic fired body having a diameter of 10 mm and a thickness of 5 mm showed a fast water absorption rate that was 90% or more of the maximum water absorption rate within 1 minute. In this example, the water absorption is a value obtained by immersing the porous ceramic fired body in water for 24 hours, and indicating the mass of the water absorbed as a percentage of the mass of the porous ceramic fired body.
Further, in the porous ceramic fired body of this example, the time for the moisture content to reach 50% of the water absorption rate was 32 hours in an environment of room temperature of 20 ° C. and relative humidity of 55%. This time indicates the time during which the water content of 50% or more of the water absorption rate can be maintained in an environment of 20% at room temperature and a relative humidity of 55%. In other words, the water content of 50% or more of the water absorption rate is maintained. It shows that it has a sustained release property that it can maintain and release moisture over 32 hours.

  In an example in which only Kanuma soil was baked at 800 ° C., the time to reach a moisture content of 50% of the water absorption rate in an environment of room temperature and 55% relative humidity was 20 hours, and only vermiculite was baked at 800 ° C. Then, the time to reach a moisture content of 50% of the water absorption rate in an environment of room temperature and relative humidity of 55% was 19 hours. The porous ceramic fired body obtained in this example maintains a water retention rate of 50% or more of the water absorption rate in a room temperature of 20 ° C. and an environment of 55% relative humidity for 20 hours or more, and sustained release of moisture release. Could be achieved.

  In the above examples, as the allophane raw material or weathered volcanic ash containing the same, the pumice layer around Kanuma City, Tochigi Prefecture was weathered and allophaneized, and in particular, what was called Kanuma soil was used. However, instead of Kanuma soil, for example, weathered volcanic ash such as Shikotsu volcanic ash, Mashu volcanic ash in Hokkaido, Towada volcanic ash in Tohoku, Hakone volcanic ash, Hakone volcanic ash, Fuji volcanic ash, Kiso Mitake volcanic ash, Oyama volcanic ash and Aso volcanic ash, Allophaneized weathered volcanic ash and weathered volcanic ash containing a large amount of imogolite can be used. In the above example, vermiculite is used, but vermiculite can be replaced with clay minerals such as mica and talc. Further, additional use of fibrous silicate minerals and inorganic silicates such as sepiolite and glass fiber is effective in improving the strength. It is preferable to use a raw material having a function of forming pores such as foamed glass powder or an organic powder that becomes pores upon firing, and a raw material having a self-curing action such as water glass and cement powder.

The present invention uses a large amount of weathered volcanic ash and vermiculite as raw materials, for example, maintains a water retention rate of 50% or more of water absorption in an environment of room temperature of 20 ° C. and 55% of relative humidity, for example, for 20 hours or more. The present invention provides a relatively inexpensive porous ceramic fired body that has a sustained release property of releasing slag and can be stably produced in large quantities. This porous ceramic fired body can be used as, for example, water retaining materials for heat island countermeasures, water retaining asphalt pavement filler materials, pavement block materials, and water retaining building materials such as roofing materials and outer wall materials. In addition, effective use of vermiculite can be achieved. Therefore, the present invention is useful for improving the environment and contributing to industrial development.

Claims (15)

A porous ceramic fired body containing a fired product of weathered volcanic ash and fired vermiculite and having an open porosity of 17% or more. A porous ceramic fired body comprising a fired product of weathered volcanic ash, a fired vermiculite, and a fired waste glass powder, and a fired body having an open porosity of 17% or more. The fired body further contains a foamed glass powder fired product, a glass fiber fired product, a sepiolite fired product, a cement powder fired product, an organic powder fired product, or a mixture of these two or more fired products. The porous ceramic fired body according to claim 1 or 2. A porous ceramic fired product comprising 30 to 90 parts by weight of a fired product of weathered volcanic ash and 10 to 70 parts by weight of fired vermiculite and having a porosity of 17% or more body. A calcined product containing 50 to 80 parts by mass of a fired product of weathered volcanic ash, 10 parts by mass of calcined vermiculite, and 10 to 40 parts by mass of calcined waste glass powder, and having an open porosity of 17% or more A porous ceramic fired body characterized by being a body. The porous vermiculite according to claim 1, 2, 4, or 5, wherein the sintered vermiculite contains in part a smaller amount of calcined mica or talc or a mixture thereof than the calcined vermiculite. Ceramic fired body. A mixture of weathered volcanic ash and vermiculite is molded, and the molded product is heated at a temperature of 500 to 1000 ° C. to produce a porous ceramic fired body having an open porosity of 17% or more. A method for producing a porous ceramic fired body. Weathered volcanic ash and vermiculite are mixed with water, alcohol or an organic solvent, and a mixture obtained by this mixing is formed. The formed product is heated at a temperature of 500 to 1000 ° C., and 17% or more is opened. A method for producing a porous ceramic fired body comprising producing a porous ceramic fired body having a porosity. A mixture of weathered volcanic ash, vermiculite, and waste glass powder is molded, and the molded product is heated at a temperature of 500 to 1000 ° C. to produce a porous ceramic fired body having an open porosity of 17% or more. A method for producing a fired porous ceramic body. Weathered volcanic ash, vermiculite, and waste glass powder are mixed in the presence of water, alcohol or organic solvent to form a mixture obtained by the mixing, and the molded product is heated at a temperature of 500 to 1000 ° C. A method for producing a porous ceramic fired body, comprising producing a porous ceramic fired body having an open porosity of 17% or more. 11. The mixture according to any one of claims 7 to 10, wherein the mixture further contains foamed glass powder, water glass, glass fiber, sepiolite, cement powder, organic powder, or a mixture of two or more thereof. The manufacturing method of the porous ceramic sintered body as described in 2. A mixture containing 30 to 90 parts by mass of weathered volcanic ash and 10 to 70 parts by mass of vermiculite is molded, and the molded product is heated at a temperature of 500 to 1000 ° C. and has an open porosity of 17% or more. A method for producing a porous ceramic fired body, characterized by producing a porous ceramic fired body. Molding a mixture containing 50 to 80 parts by weight of weathered volcanic ash, 10 parts by weight of vermiculite and 10 to 40 parts by weight of waste glass powder, and heating the molding at a temperature of 500 to 1000 ° C, A method for producing a porous ceramic fired body, comprising producing a porous ceramic fired body having an open porosity of 17% or more. The porous ceramic according to any one of claims 7 to 10 and claims 12 and 13, wherein the vermiculite contains a part of mica or talc or a mixture thereof in a smaller amount than vermiculite. A method for producing a fired body. 15. The method for producing a fired porous ceramic body according to claim 7, wherein the vermiculite is fired vermiculite, unfired vermiculite, or a mixture thereof.