JPH0256300B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention is an inorganic composition composed of water glass and hydrated silicate clay minerals, which has excellent water resistance and bending strength, and when solidified, has further improved water resistance and strength, and can be used as an inorganic paint or adhesive. It relates to products, methods of manufacturing them, and methods of solidifying the materials. Water glass, which is widely used industrially, is a concentrated aqueous solution of alkali silicate or ammonium silicate obtained by melting silicon dioxide and an alkali, and is a colorless, highly viscous liquid. When water glass is left in the air, water evaporates and solidifies, so water glass is widely used as an inorganic paint or adhesive. However, once solidified, water glass has a drawback in terms of water resistance, in that when it comes into contact with water, it absorbs water again and returns to a viscous liquid. Therefore, water glass cannot be used in products that are used in humid areas or where it comes into direct contact with water. Conventionally, various additives to be added to the above-mentioned water glass have been devised in order to compensate for this drawback. Proposed additives include polyvalent metal oxides such as zinc oxide, hydrated silicate clay minerals such as sepiolite, attapulgite, and palgorskite, and substances that adsorb or contain polyvalent metal ions such as magnesium and aluminum. ing.
However, the effects of these additives are not sufficient;
For example, although they have some degree of water resistance against water at room temperature or lower, many of them dissolve in warm or boiling water. In addition, polyvalent metal ions added to water glass as a hardening agent react quickly, so
It is impossible to use or the adhesive strength or adhesion strength is insufficient. The object of the present invention is to overcome the above-mentioned conventional drawbacks,
An inorganic composition that has good adhesive strength and bending strength, and when solidified, has extremely excellent water resistance that does not dissolve even when immersed in water at room temperature or in hot water or boiling water for a long time, and a method for producing the same. The object of the present invention is to provide a method for solidifying the same. A first invention according to the present application (hereinafter referred to as the first invention) is an inorganic composition characterized by being a mixture of water glass and a hydrous silicate clay mineral with low silicic acid content. The solidified product obtained by drying the inorganic composition according to the first invention has excellent water resistance and boiling water resistance, and does not dissolve even when immersed in boiling water for a long time. The second invention according to the present application (hereinafter referred to as the second invention) includes an alkali treatment step of immersing a hydrated silicate clay mineral in an alkaline solution to produce a hydrated silicate clay mineral with low silicic acid content; This is a method for producing an inorganic composition characterized by comprising a kneading step of kneading the inorganic composition with water glass. According to the second invention, by treating the hydrous silicate clay mineral with an alkali, a part of silicic acid such as silica in the hydrous silicate clay mineral is eluted and removed.
Due to this reduction in silicic acid content, the reaction between polyvalent ions such as magnesium and aluminum in the hydrous silicate clay mineral and water glass sufficiently proceeds, resulting in excellent water resistance and boiling water resistance. A third invention according to the present application (hereinafter referred to as the third invention) is an alkali treatment step of immersing a hydrated silicate clay mineral in an alkaline solution to produce a hydrated silicate clay mineral with less silicic acid, and the hydrated silicate clay mineral. A method for solidifying an inorganic composition comprising a kneading step of kneading and water glass to form an inorganic composition, and a heating step of heating the inorganic composition to a temperature of 80 to 600°C to solidify it. It is. According to the third invention, by solidifying the above-mentioned inorganic composition at a high temperature, a larger amount of water-insoluble substances is produced, so that the obtained solidified product has better properties than one solidified at room temperature. Water resistant and heat resistant. Furthermore, when applied as an adhesive to a metal or inorganic substrate and allowed to solidify, the solidified product exhibits stronger adhesive force than one solidified at room temperature. Hereinafter, the invention according to the present application (hereinafter referred to as the present invention) will be explained in more detail. The water glass used in the present invention is usually preferably an aqueous solution of an alkali silicate containing 10 to 70 weight percent (wt%). The alkali silicate salt is Na ₂ O・nSiO ₂ (n
=1 to 4) is common, but
Na ₂ O may be K ₂ O, Li ₂ O or (NH ₄ ) ₂ O. It is also commercially available as water glass.
It may be JIS water glass No. 1 to 3. The hydrated silicate clay mineral in the present invention is obtained by pulverizing the ore of the mineral, and its particle size is preferably within the range of 1 to 50 μm in order to obtain a uniform inorganic composition. The ore specifically includes sepiolite, attapulgite,
Montmorillonite, Kaolinite, Halloysite,
It is a fibrous or layered substance of vermiculite or talc. The above-mentioned sepiolite, attapulgite, and talc are minerals whose main components are hydrated magnesium silicate and hydrated aluminum silicate, and their structure is an aggregate of long fibers with a quadrilateral cross section of approximately 0.1 μm on each side. The fibers have a large number of holes along their length. Further, the layered material such as vermiculite has a layered structure of thin films containing magnesium silicate and aluminum silicate as main components. The alkali treatment step in the present invention involves immersing the hydrated silicate clay mineral in an alkaline solution.
This is a step of leaving it for a certain period of time to obtain a hydrous silicate clay mineral with low silicic acid content (hereinafter referred to as low silica clay mineral) according to the present invention. By the alkali treatment, a part of the silicic acid contained in the hydrous silicate clay mineral reacts with the base of the alkaline solution and is eluted into the solution, forming an amorphous portion. Thereafter, the alkaline solution is removed by washing with water or the like, and by drying, a low silica clay mineral having an amorphous portion is obtained. The above-mentioned alkaline solution may be one or more of an aqueous solution, an alcoholic solution, or a water-soluble organic solvent solution of a substance represented by MOH (M is an alkali metal such as potassium or sodium, or a base such as ammonia). Mix and use. The alkaline concentration of the alkaline solution is 0.1 to 10
A specified range is preferred. When the alkali concentration is less than 0.1 normal, the action of the alkali is weak and the reaction does not proceed sufficiently, so that the treatment takes a long time. On the other hand, if the alkali concentration is higher than 10N, the reaction between silicic acid and alkali will be accelerated, making it difficult to adjust the silicic acid content and requiring treatments such as removal of alkali and neutralization after treatment. shall be. In addition, even if the alkali concentration is within the above range, if the amount of part of the silicic acid in the clay mineral eluted into the solution is small, the reaction between the silicic acid and the alkali will be promoted.
After the clay mineral is immersed in the alkaline solution, the alkaline solution may be stirred or refluxed, and the alkaline solution may be further heated. The above-mentioned immersion time is not absolutely determined depending on the concentration and temperature of the alkaline solution, but for example,
Hours to 6 days is desirable. If immersed for less than 1 hour, the reaction will not proceed sufficiently, and if immersed for more than 6 days, all the silicic acid contained in the clay mineral will be eluted and another precipitate will be formed. Next, the low silica clay mineral is removed from the alkaline solution by a suitable method. After this, it is preferable to further wash the low silica clay mineral with water. If alkali remains in the low-silica clay mineral, it will react with the silicic acid contained in the clay mineral during the subsequent process, making it difficult to control the components of the inorganic composition according to the present invention. Wash thoroughly with water to remove alkaline content from the low silica clay mineral. Further, if it is desired to remove excess adhering water contained in the low-silica clay mineral, a drying treatment may be performed after the alkali treatment. This drying process is
Since it only removes adhering water in low silica clay minerals, it can be used in an atmosphere of air or inert gas.
It is preferable to heat and hold at a temperature in the range of room temperature to 600°C for 3 to 120 hours. A kneading step is performed in which the powder of the low-silica clay mineral obtained through the above treatment step is added to the water glass and kneaded to obtain an inorganic composition according to the first invention. The kneading step is a step for homogeneously dispersing the low-silica clay mineral in water glass, and can be carried out using a conventional mixer, ball mill, mortar, or the like. In this case, due to the above alkali treatment,
The low silica clay mineral and water glass are more likely to bond together, and the viscosity is reduced during kneading, making kneading easier. The mixing ratio of the above-mentioned low silica clay mineral and water glass is 5 to 100 g of solid component of water glass.
A ratio of ~200g is good. If the mixing ratio of the low-silica clay mineral is less than the above range, the resulting inorganic composition will tend to crack during drying and solidification, and at the same time will have insufficient water resistance after assimilation. On the other hand, if the low silica clay mineral is mixed in an amount exceeding the above range, not only will kneading become difficult, but also cracks will easily occur during drying and solidification, making it difficult to obtain sufficient strength after solidification. Next, a method for solidifying the inorganic composition, which is the third invention, will be explained. First, the inorganic composition subjected to the above-mentioned kneading step is molded into a desired shape, or the inorganic composition is applied to an object to be coated and solidified to form a molded body. Alternatively, it may be used as a bonding material for two or more base materials by bonding them together or by injecting them into a gap and solidifying them. In the above-mentioned molding, a method using a metal mold, a wooden mold, a plastic mold, or a method in which the film is placed between two films and crimped together is used. When applied, it is applied to various substrates by conventional brushing, troweling, or spraying. The above-mentioned molded or coated inorganic composition dries and solidifies simply by being left at room temperature, providing sufficient water resistance and adhesive strength. It is desirable that the standing time for natural drying at room temperature be 3 hours or more. However, in order to further improve the strength and water resistance, the solidification treatment of the inorganic composition is performed under heating. In this heated state, an exchange reaction between excess polyvalent ions such as magnesium or aluminum in the low silica clay mineral and alkali metal ions such as sodium and potassium in the water glass progresses, and water-insoluble substances are sufficiently removed. It has better water resistance, hot water resistance, and even boiling water resistance than when solidified at room temperature, and at the same time, its strength is improved because it contains less silicic acid. The processing conditions in the heating step are preferably heating at a temperature within the range of 80 to 600° C. for 1 to 10 hours in an air atmosphere or an inert gas atmosphere. When the heating temperature is lower than the above range, the inorganic composition has only the same water resistance as one air-dried at room temperature, whereas when it is dried and solidified at a heating temperature above the above range, The inorganic composition may foam during solidification. Furthermore, although the heating time varies depending on the heating temperature, it is preferable to reach the specified temperature at a relatively low heating rate and hold it for a specified period of time within the above range to prevent the inorganic composition from foaming. . Note that the material dried and solidified at a temperature near room temperature may be heated and maintained at a temperature within the above temperature range. Even in this case, it has better hot water resistance and boiling water resistance than those that are not heated. In addition, in the present invention, in the heating process for drying and solidifying, the inorganic composition made by kneading low silica clay mineral and water glass shrinks by 5 to 10% as the water decreases during drying. In order to prevent
Layered minerals such as mica and vermiculite, and oxide powders such as alumina may be added as fillers. These additives reduce the shrinkage rate of the inorganic composition during solidification, making it possible to prevent the occurrence of cracks.
Furthermore, flexibility appears. Examples of the present invention will be described below. Example 1 Sepiolite native to Spain was finely pulverized to a particle size of several microns to obtain sepiolite powder as the mineral according to the present application. The main component of the clay mineral is
62.0wt% silicon dioxide (SiO ₂ ) and 24.12wt% magnesium oxide. Add 100g of the powder to an aqueous sodium hydroxide solution with an alkaline concentration of 6N,
At a temperature of 109 °C in a flask equipped with a condenser
After refluxing for 10 hours, it was left to stand for 30 minutes. after that,
The aqueous solution was filtered, redispersed in tap water, and filtered again. This dispersion and filtration operation was repeated five times, and the material obtained by filtration was heated and dried at 80° C. for 48 hours to remove the alkaline content remaining in the material. Through this alkali treatment process, the main components of the above sepiolite are 30.1wt% SiO ₂ and 30.1wt% MgO.
The content was changed to 24.2 wt%, and a low silica clay mineral according to the present invention was obtained. Next, the raw silica clay mineral was ground into powder using a mortar and pestle. 100 g of sodium type water glass No. 3 was added to 30 g of the powder, and the mixture was kneaded using a mortar and pestle.
It was molded into a disk shape of mm. This molded body has a size of 50 mm.
Cut into a plate shape of ×10 mm and 2 mm thick, dry and solidify at room temperature for 24 hours, and then use Inert Open.
The mixture was heated at 120° C. for 4 hours to obtain a solidified inorganic composition according to the present invention. The size of the solidified product shrunk by about 2% due to the drying and heating operations described above. In addition, for comparison, raw material powder without alkali treatment was mixed, molded, and molded in the same manner and proportions as above.
A comparative solidified product was prepared by drying and heat treatment. Next, in order to confirm boiling water resistance, the above two types of solidified products were immersed in boiling water for 1.5 hours. As a result of this immersion, no change was observed in the shape or surface condition of the inorganic solidified product of the present invention or the comparative solidified product. However, after the immersion, the solidified product was taken out and the amount of Na ₂ O component eluted from the solidified product was determined by titration with hydrochloric acid.
The amount of Na ₂ O eluted was 150 mg, whereas the amount eluted from the solidified product of the present invention was 1.0 mg, indicating that the inorganic solidified product of the present invention has excellent boiling water resistance. In addition, in terms of strength, the comparison solidified product was 3
The point bending strength was 9 Kg/mm ² , whereas the solidified product of the present invention had a point bending strength of 13 Kg/mm ² , indicating that the product of the present invention is superior. Example 2 Spain-originated sepiolite was treated with an alkali in the same manner as in Example 1, dried, and then finely ground to obtain the low-silica clay mineral of the present invention. Next, add sodium type water glass No. 3 to 40 g of the powder.
200 g was added and thoroughly kneaded to obtain a sticky inorganic composition according to the present invention. Two aluminum rods with cross-sectional dimensions of 5 mm x 20 mm and length of 50 mm were prepared, and the above-mentioned inorganic composition was applied to the end surfaces of each aluminum rod. Thereafter, the coated surfaces of both rods were brought together to solidify the inorganic composition, and the two aluminum rods were bonded together to produce a tensile test piece and the adhesive strength was measured. In this case, a large number of test pieces with different solidification conditions were manufactured and the above measurements were performed. In addition, in the above-mentioned solidification process, changes in adhesive strength depending on the solidification conditions were investigated by performing the solidification at room temperature and when heating was applied.
Table 1 shows the solidification conditions for the above test piece. Test piece (1) in Table 1 was left at room temperature for 72 hours, and test piece (2) was left at a temperature of 240℃.
It was kept heated for 24 hours. In addition, as a comparative example, the test piece (S ₁ ) was bonded with a mixture using sepiolite powder that had not been treated with alkali, and was heated at a temperature of 80°C.
It was heated and held at ℃ for 24 hours. Next, for each test piece, in the as-adhered state, 40
A tensile test was conducted under three conditions: a state in which the material was kept in warm water at 450°C for 10 days, and a state in which it was kept at a high temperature of 450°C for 2 hours. The results are shown in Table 1. Note that the measured value is the average value of 10 test pieces.

[Table] Once solidified, the inorganic composition of the present invention does not deteriorate even when immersed in hot water, and has excellent adhesive properties.
It can be seen that it has water resistance and heat resistance. In comparison, in the case of the comparative example, it can be seen that the strength significantly decreases when kept in hot water or at high temperatures. 20g crushed powder
100 g of sodium type water glass No. 3 was added to the solution.
Further, 5 g of powder obtained by dry-pulverizing expanded vermiculite obtained by heating and foaming vermiculite from China was added. This was mixed, molded, and dried in the same manner as in Example 1, and then heat treated at a temperature of 250° C. for 3 hours to obtain a solidified inorganic composition according to the present invention. For comparison, a solidified product of an inorganic composition without addition of vermiculite was produced by the same treatment as above. Dimensions of the solidified product after the above drying and heating heat treatment
The change was 2% with vermiculite added, while it was 3% with no vermiculite added, confirming that the addition of vermiculite has the effect of reducing drying shrinkage. . Next, put the solidified material with the addition of vermiculite in boiling water.
When immersed for 1.5 hours, the amount of Na ₂ O eluted from the solidified product was 0.6 mg, indicating excellent water resistance. Moreover, the three-point bending strength was 8.8 Kg/mm ² . Example 4 50 g of attapulgiaite powder originating from the United States was added to an aqueous lithium hydroxide solution with an alkaline concentration of 2N, and immersed for 2 days. This was washed with water and dried in the same manner as in Example 1, and 20 g of low silica clay mineral obtained was kneaded with 100 g of lithium type water glass, and then molded and dried in the same manner as in Example 1. Next, heat treatment was performed at 120°C for 5 hours to obtain a solidified product according to the present invention. For comparison, the powder not treated with alkali was mixed, molded, dried and heat treated in the same proportions and in the same manner to produce a solidified product for comparison. The two types of solidified products mentioned above were immersed in hot water at 50°C for 2 hours.
No major changes were observed in the surface condition. However, the amount of Li ₂ O eluted from the solidified product was 45 mg from the comparative solidified product, whereas it was 2.0 mg from the solidified product of the present invention, indicating excellent hot water resistance. Example 5 Add 10 g of vermiculite powder prepared in the same manner as in Example 2 to 10 g of Turkish sepiolite powder that was treated with alkali in the same manner as in Example 1, washed with water, and dried.
Furthermore, 10 g of alumina powder, 100 g of sodium type water glass No. 3, and 100 c.c. of tap water were kneaded to prepare a paste of the inorganic composition according to the present invention, and this was applied to the surface of the foam glass insulation material using a brush. . The coated surface was dried at room temperature for 5 hours and then heated and dried at 80° C. for 24 hours. As a result of this treatment, no peeling of the coating film was observed. Even when the surface-treated foam glass was immersed in hot water at 45°C for 24 hours, the coating surface did not change in quality at all.

Claims (1)

[Scope of Claims] 1. An inorganic composition characterized by being a mixture of water glass and a hydrous silicate clay mineral with low silicic acid content. 2. An alkali treatment step in which a hydrated silicate clay mineral is immersed in an alkaline solution to form a hydrated silicate clay mineral with low silicic acid content, and a kneading step in which the hydrated silicate clay mineral and water glass are kneaded to form an inorganic composition. A method for producing an inorganic composition comprising: 3. The method for producing an inorganic composition according to claim 2, wherein the hydrated silicate clay mineral is sepiolite, attapulgite, montmorinite, kaolinite, halloysite, vermiculite, or talc. 4 The above alkaline solution has an alkaline concentration of 0.1~
3. The method for producing an inorganic composition according to claim 2, wherein the inorganic composition is a 10N solution. 5 The above-mentioned kneading step is characterized in that 0.1 to 200% by dry weight of a hydrous silicate clay mineral with low silicic acid content is added to the water glass and kneaded therein. 2. A method for producing an inorganic composition according to item 2. 6. An alkali treatment step in which a hydrated silicate clay mineral is immersed in an alkaline solution to form a hydrated silicate clay mineral with less silicic acid, and a kneading step in which the hydrated silicate clay mineral and water glass are kneaded to form an inorganic composition. and,
A method for solidifying an inorganic composition, comprising a heating step of heating the inorganic composition to a temperature of 80 to 600°C to solidify it. 7 The above alkaline solution has an alkaline concentration of 0.1~
7. The method for solidifying an inorganic composition according to claim 6, wherein the method is a 10N solution. 8 The above-mentioned kneading step is characterized in that 0.1 to 200% by dry weight of a hydrous silicate clay mineral with low silicic acid content is added to the water glass and kneaded therein based on the solid content of the water glass. A method for solidifying an inorganic composition according to item 6.