JPH044971B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to highly swellable inorganic granules that can be applied to waterproofing materials, civil engineering and construction materials, mud preparation agents for civil engineering boring, mold binders, inks, paints, and the like. (Prior art) Clay minerals mainly composed of montmorillonite, represented by bentonite, have traditionally been used as waterproof materials, civil engineering construction materials, civil engineering boring materials, and oil wells by taking advantage of bentonite's basic properties such as swelling power and viscosity. It is widely used as a mud preparation agent for drilling, a mold binder, and a soil conditioner. (Problem to be solved by the invention) However, the swelling power of this naturally occurring bentonite is at most 10 to 30 ml/2 g, and the swelling rate is extremely slow (for example, naturally occurring sodium bentonite does not completely swell. (It will take about 24 hours to complete.) Powdered bentonite also has poor dispersibility in water and has various problems in use, such as being difficult to handle. (Means for Solving the Problems) The present inventors have focused on the fact that the various properties of bentonite are related to the swelling power, which is a fundamental characteristic of bentonite, and have attempted to overcome the above-mentioned drawbacks of conventional bentonite. As a result of intensive research,
A product made by adding a sodium compound and a magnesium compound to bentonite (preferably calcium-type bentonite), adding water and kneading it, and then granulating it shows extremely high swelling power and has far superior viscosity and water dispersibility compared to natural products. The present invention was completed by discovering that bentonite granules can be obtained using the same method. That is, the present invention provides 0.1 to 10 parts by weight of at least one sodium compound selected from sodium salts, sodium hydroxide, and sodium oxide to 100 parts by weight of a clay mineral mainly composed of montmorillonite (preferably calcium-type bentonite). and 0.1 to 10 parts by weight of at least one magnesium compound selected from magnesium salts, magnesium hydroxide, and magnesium oxide, and the mixture is mixed with water and then granulated. This is what we provide. The clay mineral mainly composed of montmorillonite used in the preparation of the highly swellable inorganic granules of the present invention is not particularly limited, but natural calcium-type bentonite is particularly preferred. Further, as the sodium salt, sodium carbonate is particularly preferable, and as the magnesium salt, magnesium carbonate, magnesium chloride, magnesium sulfate, etc. are preferable. In the present invention, it is extremely important to maintain the ratio of the raw clay mineral and the sodium compound and magnesium compound within the above-mentioned specific range in order to achieve the swelling effect. That is, in the present invention, if the sodium compound used is less than 0.1 part by weight for clay minerals mainly composed of montmorillonite, the effect will not be sufficient, and if it exceeds 10 parts by weight, the clay mineral itself will cause aggregation and the desired effect will not be achieved. The swelling effect is not exhibited. This phenomenon also applies to the addition of magnesium compounds. According to the research conducted by the present inventors, clay minerals mainly composed of montmorillonite, such as natural calcium-type bentonite, hardly swell in water, and adding only magnesium compounds hardly improves the swelling power. As mentioned above, by mixing a sodium compound and a magnesium compound in a specific ratio, adding water and kneading, and reacting the sodium and magnesium ions, the swelling effect is synergistically exerted and the granules have excellent swelling properties. can be obtained. Any method may be used for adding the sodium compound and the magnesium compound, and they may be added as a powder, as an aqueous solution, or as an aqueous solution obtained by mixing and reacting both aqueous solutions in advance. Next, the amount of water added (water content) in water-addition kneading is the water content.
It is preferably 10 to 50% by weight. If the moisture content is outside this range, not only will granulation be difficult;
Perhaps because sufficient shearing force is not applied during kneading, the reaction between the clay mineral mainly composed of montmorillonite and sodium and magnesium does not proceed, making it impossible to increase the swelling power. The particle size of the granules of the present invention is not limited and can be set as appropriate depending on the purpose, use situation, etc., but is usually 0.1 to 5 mm.
is within the range of There are no particular restrictions on the granulation method. Dry granules can be obtained by granulation using a wet extrusion method, a rolling granulation method, a spray granulation method, a fluidized granulation method, a crushed granulation method, or the like. The moisture content in the dry granules is not particularly limited, but is preferably about 10% by weight or less. (Effects of the invention) The inorganic granules of the present invention have a high swelling power of 40ml/2
g or more and has an extremely fast swelling rate, so when used for example to prevent water leakage, it instantly swells upon contact with water and forms a thick waterproof phase, completely preventing water leakage. On the other hand, with conventional natural bentonite, the swelling rate is slow even when it comes in contact with water, so it takes a long time to form a waterproof phase, and the thickness of the waterproof phase is thin, so the waterproof effect is not sufficient. . Furthermore, the highly swellable inorganic granules of the present invention are highly swellable granules, so they have extremely good dispersibility in water and are free of powder, so they can be used as natural bentonite from the viewpoint of working environment and ease of handling. It has the characteristic that it is superior to Therefore,
It can be effective in applications where bentonite is used after being dispersed in water, such as mud preparation for civil engineering boring and oil well drilling, ink, and paint. It is also effective as a binder for molds in foundries, where dust control in the working environment is a problem. (Examples) Next, the present invention will be described in more detail based on Examples. Example 1 100 parts by weight of natural calcium-type bentonite was mixed with sodium carbonate and magnesium chloride in the proportions shown in Table 1, water was added, and the mixture was kneaded and granulated (granulation water content 28% by weight) to obtain a particle size of 1.2 mm. granules (moisture 10
% by weight) was obtained. The swelling power of this product was measured and the results are shown in the same table. In this example and the following examples, the swelling power test was conducted by placing 100 ml of distilled water in a 100 c.c. graduated cylinder with a stopper, and placing sample 2 in it.
The volume of the sample after swelling was measured by dropping the sample and leaving it for a day and night.

[Table] Next, the swelling rate of the granules of Experiment No. 17 in the above table was tested. For comparison, a similar test was conducted on natural sodium bentonite. The results are shown in Table 2. The swelling rate was determined by measuring the time from when the sample was placed in water until the swelling was almost completed (visually 90% or more).

[Table] Example 2 To 100 parts by weight of natural calcium-type bentonite, an aqueous solution containing 4 parts by weight of sodium carbonate and an aqueous solution containing 1 part by weight of magnesium chloride were added,
Swelling power when kneaded and granulated (Experiment No. 1) and when kneaded and granulated in the same manner as above except that the sodium carbonate solution and magnesium chloride solution were mixed and reacted in advance (Experiment No. 2) was measured. Moisture content during granulation was 28% by weight. The swelling power measurement results are shown in Table 3.

[Table] Example 3 To 100 parts by weight of natural calcium-type bentonite, 4 parts by weight of sodium carbonate and 1 part by weight of magnesium chloride were added, and after uniformly mixing, the mixture was kneaded and granulated while changing the hydration rate to determine the hydration rate and swelling. The relationship with force was measured. The results are shown in Table 4.

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Claims (1)

[Claims] 1. Clay mineral whose main component is montmorillonite
0.1 to 10 parts by weight of at least one sodium compound selected from sodium salts, sodium hydroxide, and sodium oxide and at least one magnesium compound selected from magnesium salts, magnesium hydroxide, and magnesium oxide per 100 parts by weight. 1. A highly swellable inorganic granule, characterized in that it is made by mixing 0.1 to 10 parts by weight, adding water and kneading, and then granulating the mixture. 2. The highly swellable inorganic granules according to claim 1, which are obtained by adding respective aqueous solutions of a sodium compound and a magnesium compound to a clay mineral mainly composed of montmorillonite, kneading and granulating the mixture. 3. The highly swellable inorganic material according to claim 1, which is obtained by mixing and reacting aqueous solutions of a sodium compound and a magnesium compound, adding this aqueous solution to a clay mineral mainly composed of montmorillonite, kneading it, and granulating it. Granules. 4. The highly swellable inorganic granules according to claim 1, which have a water content of 10 to 50% by weight when kneaded with water. 5. The highly swellable inorganic granules according to claim 1, which have a water content of 10 to 50% by weight during granulation.