JPH0154310B2 - - Google Patents

Description

[Detailed description of the invention]

A. Field of Industrial Application of the Invention The present invention relates to a method for producing water-permeable tiles. Conventional Techniques Conventional methods for manufacturing water-permeable tiles, i.e., tiles with communicating holes, include methods of mixing organic matter and burning it out during firing, methods of mixing raw materials with large shrinkage during firing, and foaming raw materials. There were two methods, including a method of using pores, and a method of forming communicating pores by adjusting the particle size structure. Problems to be Solved by the Invention The present invention relates to a method for adjusting the particle size structure among the various means for forming communicating holes as described above. This particle size structure adjustment method is a method in which coarse aggregate is coated with fine powder that serves as a binder, molded, and then fired.In this method, there are no intermediate particles that fill the gaps between the aggregates, so communicating pores are formed. This means that the tiles will be made into water-permeable tiles. A problem in molding a mixture without intermediate particles is shape retention, and it is particularly difficult to impart green strength to the mixture. If this green strength is weak, problems such as coarse grains at the corners are likely to break off and the shape of the molded product tends to collapse when it is removed from the mold or moved. On the other hand, if the molding pressure is increased to increase this green strength, or shape retention, the coarse aggregate will break, the particle size structure will collapse, communicating pores will be lost, and there will be no binder in the cracks, which will weaken the strength of the fired product. There is a risk of this happening. In this way, the means for forming communicating holes by adjusting the particle size structure has various problems when molding.
This cannot be said to be a satisfactory method for producing water-permeable tiles. The present invention aims to solve the above problems, and has high green strength and excellent shape retention.
Furthermore, the present invention aims to provide a method for manufacturing water-permeable tiles in which the obtained tiles have high strength and have good water permeability because they are molded using a low-pressure press. B. Structure and operation of the invention The structure of the present invention is such that fine particle powder, which becomes a binder for the aggregate, is coated on aggregate whose particle size is arranged in a narrow range through a liquid glue, and then the material is fed into a mold. The gist of the present invention is a method for producing a water-permeable tile, which is characterized in that the aggregate is press-formed under a pressure range that does not break the aggregate while being vibrated, and then fired. Means to solve the problem In order to increase green strength, that is, shape retention before firing,
The aggregate is coated with fine particle powder that acts as a binder with a sizing agent interposed, and the sizing agent improves the adhesion of the fine particle powder and makes it easier for the aggregates to temporarily stick together.Furthermore, vibration is applied during press forming. This facilitates the filling of aggregate, and enables sufficiently high shape retention and green strength to be obtained even when the press pressure is low enough not to break the aggregate. The aggregate in the present invention is, for example, natural pottery stone,
These are products such as Cerben and Shamotsu obtained by crushing ceramics, and these are coarsely crushed using a roll crusher and classified using a vibrating sieve to obtain particles with a narrow range of particle size. This narrow range of particle size, that is, aggregate with a substantially constant size, is selected and used as the raw material, but the particle size can be arbitrarily determined as large, medium, or small depending on the purpose. For example, if the aggregate is coarse particles that increase water permeability, choose one with a particle size in the range of 5,800 to 3,400μ, and as a medium-sized aggregate, choose one with a particle size in the range of 3,400 to 1,700μ. is preferable, and in the case of small aggregates, those with a particle size in the range of 1700 to 800μ are suitable. In the manufacturing method of the present invention, aggregate whose particle size is arranged within a narrow range is first wetted with a liquid sizing agent. This liquid sizing agent is, for example, a sizing agent such as starch, isobane, CMC, etc. dissolved in water.
For starch, a 10-15% aqueous solution is preferable;
A 5-15% aqueous solution is preferred for Isoban and a 1-3% aqueous solution for CMC. In other words, the aggregate is wetted with the mucus of these liquid sizing agents, and its adhesive strength improves the adhesion of the fine particle powder to the aggregate, which will be described below. In addition, this liquid glue also has the effect of promoting temporary fixation of aggregates to each other during press molding and improving the overall shape retention. Methods for wetting the aggregate with this liquid sizing agent include dipping, spraying, etc., but the simplest method is usually to throw the aggregate into a mixer, pour a low-viscosity liquid sizing agent over it, and stir. It is. Next, the fine particle powder in the present invention is a fine powder that melts and vitrifies during firing and sticks between aggregates, and this particle size is extremely small compared to the aggregate, for example, an average particle size of several tens of microns or less. It is made of powder. Specific examples of fine particle powder that acts as a binder between aggregates include Shigaraki aplite, Ayama aplite, feldspar waste mud, low stone, cement, chlorite clay, waste glaze, blue clay, and calcium carbonate. , these may be used alone or in combination as appropriate. When aggregate with a fairly high viscosity and almost uniform size is sprinkled with fine powder of very small particle size and molded, there are no intermediate particles to fill in the gaps between the aggregates, so these gaps remain as communicating pores even after firing. The remaining water permeability remains. However, if the amount of fine particle powder is too large, there is a risk that the vitrified fine particle powder will fill the above-mentioned gaps.Therefore, there is a preferable range for the amount of fine particle powder to be blended as shown below. In other words, it is desirable to coat the aggregate with fine particle powder in an amount 0.2 to 0.4 times the weight of the aggregate before molding. The amount of coating of this fine powder is equal to the amount of aggregate.
If the amount is less than 0.2 times, the thickness of the coating layer will be less than 6% of the radius of the aggregate, and the strength of the resulting tile will decrease as the adhesion force between the aggregates due to firing becomes smaller. be. on the other hand,
When the coating amount of this fine particle powder exceeds 0.4 times the amount of aggregate, the thickness of the coating layer will be 12% or more thicker than the radius of the aggregate, and the adhesion between the aggregates will be reduced by firing. Although the strength is increased, there is a risk that the communicating pores are more likely to be blocked by the vitrified fine particles, resulting in a decrease in water permeability. Therefore, it is most desirable that the coating amount of this fine particle powder be 0.2 to 0.4 times the amount of the aggregate. The method of coating the aggregate with this fine particle powder is, for example, by applying the above-mentioned liquid sizing agent to the aggregate in a mixer, and then adding a predetermined amount of the fine particle powder into the mixer and stirring. It is sufficient to mix until almost uniform adhesion is obtained. In addition, when selecting the fine particle powder that is this binder, it is desirable to use one whose expansion coefficient matches that of the aggregate as much as possible during firing.If this expansion coefficient has a large difference from that of the aggregate, Cracks occur and cause a decrease in strength. In this way, a predetermined amount of fine powder is coated almost uniformly around the aggregate, and this is then fed into a mold and pressurized to form the material.In the present invention, at the same time as this application, vibration is applied. It has become a way of giving. In this case, it is desirable to increase the pressure, as increasing the density between the aggregates improves shape retention and green strength, but if the pressure is too high, cracks may easily occur in the aggregate. When the aggregate is cracked, the size of the aggregate becomes irregular, and particles of intermediate particle size may clog the communicating holes, and since there is no fine powder as a binder between the cracks, the strength after firing will decrease. This causes problems such as . Therefore, it is necessary to limit the pressure applied during press molding to a range that does not cause the aggregate to crack. In other words, during press forming, the pressure is limited to a range that does not cause the aggregate to crack, and the press forming is performed while applying vibrations so that the aggregate becomes as dense as possible even with this low pressure. For example, the amplitude is 2 to 8 mm and the frequency is 1 minute.
When press forming is performed while applying strong vibrations of 4,000 to 8,000 times, the aggregate is densely packed, resulting in a compact molded product that retains its shape better than simply pressing from above at high pressure, even at a lower pressure. is obtained. Through this press forming, a temporary fixing force acts between the aggregates to obtain a molded product in the desired shape, but the above-mentioned glue accelerates this temporary fixing, and the vibration and pressure mentioned above promotes this temporary fixation. By working synergistically with the close packing, more stable shape retention is achieved. The pressure applied during press forming varies depending on the type and size of the aggregate, but usually
A range of 0.5 to 1.5 Kg/cm ² is preferred. This pressing force is very small, about 1/10 or less of that in the case of no vibration as in the example described later.
It turned out that the effect of this vibration was unexpectedly large. In addition, this vibration provides excellent shape retention and strength after firing with low pressing force, and the fracture rate of the aggregate is greatly reduced, resulting in extremely high water permeability. Molding by applying pressure while vibrating is the greatest feature of the present invention, and achieves excellent effects that far exceed expectations. The molded body that has been molded in this manner is transferred to a firing device and fired in a conventional manner to obtain the water-permeable tile that is the object of the present invention. Example Tile Shamotsu white aggregate with a particle size in the range of 3400 to 1700μ (medium aggregate) is selected, and this aggregate is put into a mixer for concrete, and 10% The aqueous starch solution was added little by little while stirring. When the sizing agent is uniformly adhered to the entire aggregate surface, 30% of the aggregate amount of Shigaraki aplite is added as a fine powder binder, and stirred so that the fine powder binder is uniformly adhered to the entire aggregate surface. did. Next, this fine powder binder-adhered aggregate was fed into a mold and molded under various conditions as shown in Table 1, comparing vibration press molding and simple press molding.

[Table] This test No. 1 is an example of the present invention, and the other tests are comparative examples without vibration. When the fracture rate of the aggregate and the bulk density of the molded body were measured under these molding conditions, the results shown in Table 2 were obtained. Note that this destruction rate is expressed as an increase rate of particles of 840μ or less. Table 2 shows the evaluation of shape retention, which was determined based on whether the molded product could be held and moved after molding.

[Table] From this table, Test No. 1, which is an example of the present invention,
Since the pressure applied during press forming is small, the fracture rate is extremely low, and the resulting molded product has a considerably high bulk density, requiring 15 to 20 times the press force when press forming without vibration. The bulk density is such that Therefore, it also has excellent shape retention, that is, green strength, and will not lose its shape even if it is held in the hand and moved to a baking device or the like. Next, these molded bodies were fired at 1250℃ for 1 hour,
The bending strength and water permeability of the fired body were measured. The results are shown in Table 3. In addition, 30mm x 100mm x 20mm is used for measuring bending strength.
pieces were used.

[Table] From this table, test No. 1, which is an example of the present invention, is 15
It has a bending strength comparable to that obtained by pressing only with ~20 times the pressure, and its water permeability is extremely good because the aggregate is hardly destroyed, and in Test Nos. 2 to 5, it did not break. It is judged that as the ratio increases, the water permeability becomes extremely poor. C. Effects of the Invention As explained in detail above, the present invention includes interposing a liquid sizing agent when coating fine powder serving as a binder around aggregate;
This is a method for producing water-permeable tiles that has the major feature of being able to form with low pressure by applying vibration during press forming. Therefore, this adhesive makes it easy to temporarily bond between the aggregates during press molding, and since the aggregates are densely packed by vibration, they have strong shape retention, that is, green strength, and there are almost no problems such as collapse during transfer to firing. Since it can be formed with a pressure less than 1/10 of the pressure without vibration, there is almost no destruction of the aggregate, and the water permeability after firing is extremely high. In addition, the bulk density is high due to the vibration pressurization, and the strength of the tiles obtained by firing is also sufficiently high, so that the tiles have a wide range of uses. It has various excellent effects such as.

Claims (1)

[Scope of Claims] 1. Fine particle powder, which will become the binder of the aggregate, is coated on aggregate whose particle size is arranged in a narrow range through a liquid adhesive, and then the material is fed into a mold and the above-mentioned A method for producing a water-permeable tile, which is characterized by press-forming under a pressure range that does not break the aggregate, and then firing. 2. Claim 1, wherein the coating amount of the fine particle powder is 0.2 to 0.4 times the weight ratio of the aggregate.
2. Method for manufacturing water permeable tiles as described in Section 1.