JPH0516391B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a porous ceramic molded body that uses granite and has sound absorption and water permeability. [Conventional technology/problems] Existing porous ceramic molded bodies are mainly produced by crushing fired porcelain into granules, classifying the porcelain particles to obtain porcelain particles of appropriate size, and adding an inorganic binder to the porcelain particles. , which is formed into a plate shape and then fired again, making it expensive as it requires two firing steps. In addition, porous ceramic materials that utilize ordinary rocks themselves are not known, and in particular, currently,
Only a small portion of the granite mined from granite quarries is used as industrial or building materials, and the rest cannot be used. Recently, ``water-permeable ceramic'' using ordinary rocks such as granite has been proposed in Japanese Utility Model Publication No. 61-86437. However, in the case of granite, which mainly consists of feldspar, silica and mica, since the thermal expansion coefficients of feldspar and silica are different, there is a problem that when fired at a temperature of 800°C or higher in the firing furnace, the surface becomes brittle and the strength is not achieved. It was hot. The purpose of the present invention is to solve the above-mentioned strength problems,
An object of the present invention is to provide a porous ceramic molded body using granite that is inexpensive and has excellent sound absorption and water permeability, and to effectively utilize granite waste. [Means for Solving the Problems] Therefore, the present invention provides a molded body obtained by pressure-molding a mixture of granite having a particle size of 0.5 to 5 mm, a sintering agent, a forming aid, and water, and drying the mixture. A porous molded body is impregnated with a binder slurry consisting of finely pulverized granite with a particle size of 104 microns or less, an inorganic alkali powder, and water, or the binder slurry is sprayed onto the surface of the molded body, and finally fired. A method for manufacturing a quality ceramic molded body. [Function] The granite used to produce the porous ceramic molded body has a grain size of 0.5 to 5 mm, preferably 1 to 3 mm.
It is something that has. If granite with a particle size of less than 0.5 mm is mixed, it is undesirable because the sound absorption and strength of the resulting molded product will decrease and the surface will become brittle.
In addition, if granite with a grain size exceeding 5 mm is mixed, although the sound absorption properties are good, the strength of the molded body is
This is particularly unfavorable since the compressive strength becomes low. The amount of granite to be blended is not particularly limited, but it is preferable that the total amount of granite and sintering agent is 75 to 90% by weight and 10 to 25% by weight of sintering agent. The content of granite is less than 75% by weight,
In other words, if the amount of sintering agent added exceeds 25% by weight,
This is undesirable because it reduces sound absorption performance, and
If the granite content exceeds 90% by weight, that is, if the sintering agent content is less than 10% by weight, the surface of the molded body becomes brittle and the strength decreases, which is not preferable. Examples of the sintering agent that can be used in the method of the present invention include soda-based lead-free glass waste, inorganic alkali powder such as sodium carbonate, and kaolin. In addition, finely crushed granite with a particle size of 104 microns (150 mesh) or less also has the effect as a sintering agent, and as a sintering agent, finely crushed granite with a particle size of 104 microns or less is mixed with the above-mentioned inorganic alkaline powder. It can also be used as Here, if the particle size of the finely pulverized granite used as a sintering agent exceeds 104 microns, it is not preferable because the sintering reactivity deteriorates and the effect as a sintering agent decreases. The same can be said of the particle sizes of other sintering agents.
Note that the finely ground granite with a particle size of 104 microns or less used as a sintering agent is different from the raw material granite in that it is mixed with inorganic alkaline powder and melts during firing to act as a sintering agent. Molding aids that can be used in the present invention include plastic clay materials such as bentonite, aluminum phosphate as an inorganic binder, and CMC (carboxymethyl cellulose) as an organic binder.
Examples include MC (methyl cellulose) and PVA (polyvinyl alcohol). The amount of forming aids to be blended is not particularly limited, but it is sufficient to add the amount necessary to maintain dry forming strength (varies depending on the shape, size, etc. of the formed object). It is 5 to 15% by weight based on the total amount of binder. When the amount of molding aid is less than 5% by weight,
It is undesirable due to insufficient dry strength, and
If it exceeds 15% by weight, moldability and sound absorption properties are reduced, which is undesirable. In addition, the amount of water blended is preferably an amount that provides mold retention during pressure molding, and it is undesirable to use too much or too little because the mold retention during molding will be insufficient. It is preferably 5 to 15% by weight of the total amount of raw granite, sintering agent and forming aid. Granite, a sintering agent, a forming aid, and water are mixed at the above-mentioned mixing ratio, and the mixture is pressure-molded into a predetermined shape. The molding pressure is preferably about 30 to 100 kg/cm ² . If the molding pressure is less than 30 Kg/cm ² , it is not preferable because the desired strength cannot be imparted to the resulting molded product, and if it exceeds 100 Kg/cm ² , although the strength increases, the apparent porosity will decrease. This is undesirable because it lowers the sound absorbing properties. The porous molded body thus obtained is dried. Isn't there a particular limit to the drying temperature?
The temperature is preferably 110° C. or lower, and as a guideline for the degree of drying, it is desirable that the moisture content of the molded product is 2% or lower. Next, the dried molded body is impregnated with a binder slurry, or the binder slurry is sprayed onto the surface of the molded body. This binder slurry consists of finely ground granite with a particle size of 104 microns (150 mesh) or less, an inorganic alkaline powder, and water. If the particle size of the finely ground granite used in the binder slurry exceeds 104 microns (150 mesh), the sintering reactivity will deteriorate and the strength-enhancing effect will decrease, which is not preferable. Particle size is 104 microns (150
Desired properties such as strength and sound absorption can be obtained by using the following finely pulverized granite. The amount of finely pulverized granite varies depending on the type of inorganic alkaline powder, but it is 50 to 80% by weight of the total amount of finely pulverized granite and inorganic alkali powder, that is, 20 to 50% by weight of inorganic alkaline powder. It is preferable that The reason why the blending amount of finely crushed granite is 50 to 80% by weight is that it is effective in increasing the strength during firing and at the same time maintains sound absorption performance. 80% by weight
Addition of finely pulverized granite in excess of 20% is undesirable because it causes problems such as insufficient strength, reduced sound absorption performance, and cost. The inorganic alkaline powder acts as a binder that lowers the melting temperature of the finely pulverized granite and increases the melting rate of the finely pulverized granite, and requires a blending amount corresponding to the finely pulverized granite. The blending amount of the inorganic alkali powder is as described above, and if the blending amount is less than 20% by weight, the sintering speed of the finely pulverized granite will decrease, resulting in a loss of strength, which is undesirable. %, it is not preferable because the sound absorption performance and strength deteriorate and at the same time problems arise in terms of cost. Examples of the inorganic alkali powder include soda-based raw materials such as sodium carbonate, sodium borate, and soda-based lead-free glass waste, and the particle size of these powders is preferably 104 microns or less for the same reason as finely ground granite. . The amount of water mixed is 50 to 60% by weight based on the solid content.
is preferred. If the water content is less than 50% by weight, the binder slurry becomes viscous and difficult to apply by spraying, which is undesirable. If it exceeds 60% by weight, the binder slurry becomes dilute. If it becomes too much, unnecessary moisture will increase on the molding,
This is undesirable because it causes a decrease in the shape retention of the molded article. The above-described dried molded body is impregnated with a binder slurry having the above-mentioned mixing ratio, or the binder slurry is spray-coated onto the surface of the molded body. By applying this binder slurry to the surface of the molded body, the finely pulverized granite in the binder slurry is reacted and sintered during the next firing step, thereby improving the strength of the molded body. The degree of impregnation or spray application of the binder slurry can be varied depending on the desired shape, strength and sound absorption properties of the porous ceramic molded body. The advantages of using finely crushed granite for the binder slurry are: It is the same raw material as the compact; The fine powder generated when granite is crushed and classified can be used as is; and It is inexpensive. can be mentioned. The molded body thus obtained is finally fired. Firing in an oxidizing (OF) atmosphere at a maximum temperature of 1000℃
It is desirable that the temperature be maintained at a maximum temperature of 1 hour or longer at a temperature of ~1150°C with a heating rate of 50°C/hour to 100°C/hour. The porous ceramic molded article obtained as described above has excellent strength and sound absorption properties. In addition, the differences in the colors of the minerals (feldspar, silica, and mica) that make up granite give the resulting porous ceramic molded body a unique design, and
On the other hand, by removing mica by magnetic separation, colored substances are removed and the color becomes white, so it is possible to freely color the binder slurry after pressure molding and drying. In addition to improving the strength of porous ceramic molded bodies, they can be colored in a wide range of colors. [Example] The present invention will be further explained with reference to Examples (hereinafter simply referred to as "examples" unless otherwise specified). Example 1 Particle size 1 to 3 at the blending ratio listed in Table 1 below.
A mixture consisting of a sintering agent (lead-free glass), a forming aid (bentonite) and water was pressure molded onto mm granite and dried at 105°C for 14 hours. next,
50% by weight of finely ground granite of 104 microns (150 mesh) or less, 50% by weight of inorganic alkaline powder (lead-free glass waste), and 55% by weight based on the total amount of finely ground granite and inorganic alkali powder. % of water was formed and spray-coated onto the surface of the dried molded article at a solid content of 150 g/m ² . The obtained molded body was heated in an oxidizing atmosphere at a heating rate of 80°C/hour for 13 hours,
It is then fired by holding it at 1050℃ for 1 hour.
A porous ceramic molded body was obtained. The properties of the porous ceramic molded body obtained are also listed in Table 1 below. Example 2 Using the compounding ratios listed in Table 1 below, use 10% by weight each of granite fine powder with a particle size of 104 microns (150 mesh) or less and lead-free glass waste as the sintering agent, and set the firing temperature to 1100℃. Example 1 above except that
A porous ceramic molded body was obtained in the same manner as above.
The properties of the porous ceramic molded body obtained are listed in Table 1 below. Comparative Example 1 The molded product obtained by pressure molding and drying in Example 1 was fired under the same operating conditions as in Example 1 without spraying the binder slurry to obtain a ceramic molded product. The properties of the obtained ceramic molded body are also listed in Table 1 below. Comparative Example 2 A ceramic molded body was obtained in the same manner as in Example 1 using granite having a grain size of more than 5 mm and up to 10 mm. The properties of the obtained ceramic molded body are also listed in Table 1 below. Comparative Example 3 Granite with a grain size of 5 mm or less (i.e. 0.5
A ceramic molded body was obtained in the same manner as in Example 1 using a mixture of granite with a grain size of less than mm. The properties of the obtained ceramic molded body are also listed in Table 1 below.

[Table]
The molded bodies obtained in Examples 1 to 2 and Comparative Examples 1 to 3 described above were measured according to JIS A1405 "Method for measuring normal incidence sound absorption coefficient of building materials by in-pipe method". FIG. 1 shows the results obtained from the measurements, with the vertical axis of the graph representing the normal incidence sound absorption coefficient and the horizontal axis representing the center frequency. A to E in the figure are the measurement results of the normal incidence sound absorption coefficient of the back air layer 0 of Examples 1 to 2 and Comparative Examples 1 to 3, respectively. [Effects of the Invention] The porous ceramic molded body produced by the method of the present invention effectively utilizes granite waste, which is difficult to process at present, and can produce porous ceramic molded bodies that have the same characteristics as existing porous ceramic molded bodies. The body can be manufactured at low cost. Furthermore, since the porous ceramic molded product of the present invention does not undergo heat shrinkage, it can be made into large plates, and can be used in any field where existing porous ceramic molded products are used. It can also be used extensively as interior and exterior materials for buildings.

[Brief explanation of the drawing]

Figure 1 shows the results of measurements performed on the molded bodies obtained in Examples 1 to 2 and Comparative Examples 1 to 3 above using JIS A1405 "Method for measuring the normal incidence sound absorption coefficient of building materials using the in-pipe method". It is a graph.

Claims (1)

[Claims] 1 A mixture of granite with a particle size of 0.5 to 5 mm, a sintering agent, a forming aid, and water is pressure-molded and dried, and the resulting molded body is mixed with finely ground granite with a particle size of 104 microns or less, and an inorganic alkaline base. A method for producing a porous ceramic molded body, which comprises impregnating the molded body with a binder slurry consisting of powder and water, or spraying the binder slurry onto the surface of the molded body, and finally firing.