JPH01249678A - Production of water permeable inorganic material - Google Patents

Abstract

PURPOSE:To obtain a lightweight water permeable inorg. material useful as a water permeable flooring material, a gas permeable wall material, etc., at a low energy cost by mixing Shirasu (volcanic glass) with an alkali carbonate, a blowing agent and Shirasu balloons and calcining the mixture. CONSTITUTION:100 pts.wt. mixture consisting of 100 pts.wt. Shirasu of <=5mm particle size, especially Yoshida Shirasu, 3-40 pts.wt., preferably 5-20 pts.wt. alkali carbonate, preferably Li2CO3 or Na2CO3 having a particle size equal to or smaller than that of the Shirasu and <=2 pts.wt. blowing agent, preferably SiC, Si3N4 or AlN having a particle size equal to or smaller than that of the Shirasu is mixed with 100-300 pts.wt. Shirasu balloons preferably having 30-100mum particle size, 0.15-0.30 bulk specific gravity and 0.05-0.06kcal/m<2>.hr. deg.C heat conductivity. The resulting mixture is calcined at 800-1,000 deg.C to obtain a water permeable inorg. material.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for manufacturing a water-permeable inorganic material used for water-permeable materials, breathable wall materials, and the like.

(Conventional technology) Recently, in urban areas, as a result of the progress in paving with non-permeable inorganic materials, rainwater flows almost directly into sewage systems, causing overflows. As a result, efforts are beginning to be made to allow rainwater to infiltrate into the soil.

By the way, Shirasu, which is a glassy mineral, is widely distributed throughout Japan, is in the form of a fine powder, and its composition is almost constant.It has a particularly high alumina content and a coefficient of thermal expansion of 40 to 4.5 x 1.
It has recently attracted attention because of its small size of 0-''cm/cm'C, and it is known that it can be mixed with a foaming agent and a flux and fired to create a water-permeable inorganic material. A technique is known in which a water-permeable inorganic material is obtained by attaching a spherical glass balloon obtained by rapidly heating the balloon with water glass or a plastic binder.

(Problems to be Solved by the Invention) However, when using whitebait, not only is it heavy and the holes between the particles are clogged, making it impossible to obtain the desired water permeability, but also it cannot be used at high temperatures of 1200'C or higher. However, when using shirasu balloons, water resistance is high when water glass is used as a binder, and flame resistance is low when using plastic binder. There was a problem that it could not be used stably for a long time because of its inferiority.

(Means for Solving the Problems) The present invention aims at solving the problems of the prior art and obtaining a lightweight water-permeable inorganic material at low cost without using a binder. 100 parts by weight of a mixture consisting of 100 parts by weight of shirasu, 3 to 40 parts by weight of alkali carbonate, and 0 to 2 parts by weight of a blowing agent and 100 to 300 parts by weight of shirasu balloons are mixed and fired. This is the summary.

In the present invention, it is preferable that the shirasu be made into as fine a particle as possible so as to be densely sintered to form fine bubbles, and preferably a particle size of 15 μm or less that has been crushed by a ball mill or a vibrating mill. A material with a diameter of 5μ or less is used. Also, it is preferable to use one with a small amount of crystalline minerals, and the most preferable is the so-called "Yoshikawa Shirasu" produced in Yoshimochi Town, Kagoshima Prefecture.

The alkali carbonate used in the present invention functions as a flux, and lithium carbonate, sodium carbonate, etc. having the same particle size or less as Shirasu are preferably used.
3 to 40 parts by weight, preferably 5 to 2 parts by weight
Add 0 parts by weight. Since lithium carbonate has a strong effect of lowering the melting point of Shirasu, it can be added in a small amount, but in the case of sodium carbonate, it is necessary to add 1.5 to 2.5 times as much to obtain the same effect of lowering the melting point. If the amount added is less than 3 parts by weight,
If the foaming temperature exceeds 1000 degrees, the balloon will disappear, and if it exceeds 40 parts by weight, the melting point will drop significantly.
The viscosity becomes too low and mixing with shirasu is impaired, and when a blowing agent is added, the bubbles are crushed and only a non-uniform foam is obtained.

The blowing agent used in the present invention is preferably silicon carbide, silicon nitride, aluminum nitride, or a mixture thereof, which has a particle size equal to or smaller than that of Shirasu.
It is preferable to add 2 parts by weight or less based on the weight part.

When used, it prevents excessive contraction of the Shirasu balloon,
The degree of water permeability can be adjusted; however, if the amount added exceeds 2 parts by weight, the bubbles will burst and become rough and non-uniform.

In the present invention, to obtain a mixture consisting of whitebait, alkali carbonate, and foaming agent, the ingredients are crushed in a crusher for 30 minutes.
Preferably, the mixture is stirred for at least 2 minutes.

In the present invention, Shirasu balloons of various sizes are used in order to maintain the gap between the balloons, and the smaller the balloon diameter, the lower the water permeability, and conversely, the larger the balloon diameter, the lower the water permeability. Becomes large. Normal particle size 30 to 10
0 μ, bulk specific gravity 0.15 to 0.30, thermal conductivity 005 to 0.06 Kcal/m”h゛C, and based on 100 parts by weight of the mixture of whitebait, alkali carbonate, and blowing agent. It is necessary to add 100 to 300 parts by weight.If the particle size is smaller than 30μ, the water permeability will be significantly reduced, and if it is larger than 100μ, the strength will be significantly reduced.

If the amount added is less than 100 parts by weight, the water permeability will be significantly reduced, and if it exceeds 300 parts by weight, the strength will be significantly reduced.

In the present invention, firing is performed by placing a mixture of whitebait, alkali carbonate, a foaming agent, and a whitebait balloon in a ceramic dish or heat-resistant steel container, and heating the mixture in an electric furnace for 800 min.
It is preferable to carry out the treatment at a temperature of 1000°C or higher, for example 850 to 950°C, for about 40 minutes.

(Function) The method for producing a water-permeable inorganic material of the present invention includes 100 parts by weight of a mixture consisting of 100 parts by weight of Shirasu, 3 to 40 parts by weight of alkali carbonate, and 0 to 2 parts by weight of a blowing agent, and 100 parts by weight of Shirasu balloons.
Since the mixture is mixed with 300 parts by weight of shirasu and fired, the individual shirasu balloons are heated and contracted in a fused state due to the mixture of shirasu and alkali carbonate, which is a flux, and the gaps between the shirasu balloons are expanded, and the binder is A water-permeable inorganic material can be formed at a heating temperature of 1000°C or less without using it.

(Example) Examples of the manufacturing method of the present invention will be specifically described below.
The invention is not limited to the examples.

Example 1 100 parts by weight of a mixture consisting of 100 parts by weight of Yoshikawa Shirasu, 15 parts by weight of lithium carbonate (manufactured by Kisoda Chemical Co., Ltd.), and 1 part by weight of silicon carbide as a blowing agent (manufactured by Pacific Random Co., Ltd. R (>RFC))
parts by weight and 100 parts by weight of Shirasu balloons were placed in a plastic bag, mixed for 10 minutes, placed in a ceramic vessel, and heated at 850'C in an electric furnace (manufactured by Motoyama) for 4 hours.
The mixture was heated for 0 minutes and slowly cooled over 3 hours. As a result, a plate-shaped water-permeable material having a bulk specific gravity of 0.71 was obtained.

Example 2 Mixture 10 consisting of 100 parts by weight of Yoshikawa whitebait, 7 parts by weight of lithium carbonate (manufactured by Kishida Chemical Co., Ltd.), and 1.5 parts by weight of silicon carbide (RC-BFC, manufactured by Pacific Random Co., Ltd.) as a blowing agent.
0 parts by weight and 200 parts by weight of Shirasu balloons were placed in a plastic bag and mixed for 10 minutes, then placed in a ceramic vessel and heated at 950'C for 40 minutes in an electric furnace (manufactured by Motoyama). It was slowly cooled down over time. As a result, a plate-shaped water-permeable material having a bulk specific gravity of 0.53 was obtained.

Example 3 Molding was carried out under the same conditions as Example 2 except that 1.5 parts by weight of silicon carbide was not added. As a result, a plate-shaped water-permeable material having a bulk specific gravity of 0.80 was obtained.

Comparative Example 1 Example 1 except that 100 parts by weight of Shirasu balloon was not added.
Molding was carried out under the same conditions. As a result, only a semi-sintered product with cracking was obtained.

Comparative Example 2 Example 2 except that 200 parts by weight of Shirasu balloon was not added.
Molding was carried out under the same conditions. The result is a completely sintered
Only water-impermeable products were obtained.

(Effects of the Invention) The method for producing a water-permeable inorganic material of the present invention includes 100 parts by weight of a mixture consisting of 100 parts by weight of Shirasu, 3 to 40 parts by weight of alkali carbonate, and 2 parts by weight of a blowing agent O, and 100 parts by weight of a Shirasu balloon.
Since this is a method of mixing 300 parts by weight of shirasu with 300 parts by weight and firing, the individual shirasu balloons are heated and contracted in a fused state due to the mixture of shirasu and alkali carbonate as a flux,
Since the gap between the whitebait balloons is expanded, the water permeability is significantly improved compared to when only whitebait is used, and the firing temperature is lower, which has the advantage of lower energy costs. There is no problem when the material sticks to the material, and the overall advantage is that a lightweight, water-permeable inorganic material can be manufactured at low cost.

Claims (1)

[Claims] 1. Mixing 100 parts by weight of a mixture consisting of 100 parts by weight of Shirasu, 3 to 40 parts by weight of alkali carbonate, and 0 to 2 parts by weight of a blowing agent and 100 to 300 parts by weight of Shirasu balloons;
A method for producing a water-permeable inorganic material, which comprises firing.