JPH0371373B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing artificial aquakleptite. Natural aquacleptite is a mineral that is usually produced in small amounts with basic rocks such as chlorite and serpentine, and is mainly composed of hydrated silicate of magnesium, as well as small amounts of iron and aluminum, which gives it a brown color. The colored ones are collected. However, no attempt has been made to artificially produce this substance. Recently, the crystal structure of aquakleptite has been revealed (Shimoda,
Clay Science Vol. 2, pp. 138-146, published in 1965), this material has a crystal structure similar to sepiolite (manufactured by Edoplus Takeda Pharmaceutical Co., Ltd.), and also has the same adsorption performance as sepiolite. have. Therefore, in addition to having the same uses as sepiolite, aquakleptite molded products have the property of emitting discontinuous crackling sounds when they come into contact with water and adsorb it.
For example, it can be used as a sensor that converts water adsorption into sound, such as in river flood warning devices, water level meters in baths and aquariums, and diaper wetness detectors. Until now, no consideration has been given to the industrial use of aquakleptite, but according to the present invention, aquakleptite of various purity can be produced artificially and in large quantities from pure white aquakleptite. This enables its industrial use. That is, in the present invention, a magnesium silicate gel is produced by mixing sol silicic acid and a magnesium compound in an atomic ratio of magnesium to silicon in the range of 0.48≦Mg/Si≦1, and the pH of this gel is adjusted to 8. This is a method for producing artificial aquakleptite, which is characterized by adjusting the temperature to ~13.5 and then heating it to approximately 80 to 350°C in the presence of water. Examples of the sol-form silicic acid that can be used in the present invention include sol-form silicic acid generally called silica sol (for example, commercially available products such as Snowtex N manufactured by Nissan Chemical Industries, Ltd. and Cataloid Catalysts Chemical Industry Co., Ltd.). For example, an aqueous solution of an alkali silicate such as water glass, sodium silicate, potassium silicate, lithium silicate, ammonium silicate, etc. is treated with a hydrogen ion type ion exchange resin to produce silicate sol acid, and the pH of this product is A water-soluble sol with a pH of 3 to 11, or a silicate sol containing a salt made by adding an aqueous solution of an alkali silicate such as water glass to an aqueous solution of an inorganic acid such as hydrochloric acid or sulfuric acid. Examples include a hydrogel produced by adding water glass to an aqueous acid solution and leaving it for a while, or a sol produced by washing with water and grinding in a wet state. Furthermore, a sol-like dispersion of silicic acid can be prepared by dispersing finely powdered silicic acid such as white carbon or Aerosil produced by a wet process in water, and this can also be used. Magnesium compounds that can be used in the present invention include magnesium salts such as magnesium chloride, magnesium sulfate, basic magnesium carbonate, and basic magnesium/aluminum carbonate; magnesium oxides such as magnesium oxide and magnesium hydroxide; Inorganic magnesium compounds such as magnesium hydroxide and e.g. magnesium alcoholates,
Organomagnesium compounds such as magnesium acetate can be used. Among these magnesium compounds, particularly preferred are magnesium chloride, magnesium hydroxide, or basic salts that have a hydroxyl group in neutral to alkaline water. Mention may be made of the salts that can be produced. These magnesium compounds are usually used in a solid state, but water-soluble ones may be used in that water-soluble state. Also,
As for solid substances, powders or fine powders are used. The above-mentioned sol-form silicic acid and magnesium compound are
Atomic ratio of magnesium and silicon is 0.48≦
They are mixed in amounts such that Mg/Si≦1, preferably 0.6≦Mg/Si≦0.75. When both are uniformly mixed in a dispersed state while stirring, a paste-like magnesium silicate gel is immediately produced.
Although such a gel formation reaction proceeds satisfactorily at room temperature, it may be heated if necessary. The magnesium silicate gel obtained in this way can be adjusted from neutral to alkaline, preferably by adding aqueous ammonia, organic amines such as morpholine, and alcohol amines such as ethanolamine and triethanolamine, as necessary. 8～
Adjust to 13.5. The magnesium silicate gel whose pH has been adjusted in this way is then heated to about 85 to 350°C, preferably 100 to 280°C, in such a state that water does not evaporate. Depending on the heating temperature, approximately 10 to 10 hours
If such heating continues for several days, aquakleptite crystals will form. The generated aquakleptite crystals can be collected by methods such as centrifugation or filtration, and artificial aquakleptite can be obtained by drying the obtained crystals at approximately 100 to 300°C. . The artificial aquakleptite thus obtained is generally a white powder. In addition, by using a compound containing cobalt, manganese, nickel, iron, zinc, copper, etc. as part of the magnesium compound instead of the above magnesium compound, in addition to normal aquakleptite, the same type of aquakleptite containing these metal ions can be produced. A mixed crystal is obtained, and artificial aquakleptite with various colors can be obtained depending on the type of metal. For example, artificial aquacleptite containing cobalt is pink when it absorbs water, but pale blue when dried, and by adsorption, an indicator with color and sound can be obtained. You can also do it. Also, mixing of gelled silicic acid and magnesium is carried out in water, but in addition to water, glycol,
Polyhydric alcohols such as polyethylene glycol and glycerin, or water-soluble cellulose (hydroxyethyl cellulose, methyl cellulose, etc.)
There is nothing wrong with using a system that adds . The artificial aquakleptite synthesized according to the present invention exhibits characteristic X-ray powder diffraction as shown in Figure 1. Hereinafter, this will be explained in detail by giving examples. Example 1 Add 116 g of magnesium hydroxide Mg(OH) ₂ to 1.8 kg of Snotex N (silica sol manufactured by Nissan Chemical Industries, Ltd.) containing 10% SiO ₂ and mix it with a household mixer until it becomes homogeneous. A slurry is obtained. This slurry is stored so that water does not evaporate (this slurry is hereinafter referred to as pregel A). Take about 50g of Pre-Gel A and evaporate the water at 100°C to make a powder. Take 2.5 g of this powder, add 14 ml of 15% ammonia water, and stir thoroughly. Put this in a 20ml Teflon container, seal it, and put it in an autoclave with an internal volume of 100ml.
Add 20ml of water to the outside, seal the autoclave, heat it from the outside to bring the internal temperature of the autoclave to 280-300℃, and leave it at that temperature for one week. After one week, cool the autoclave and remove the Teflon container inside. Separate the white precipitate inside, wash with water, and dry at 100°C to obtain 2.2 g of white powder. When this product was subjected to X-ray powder diffraction analysis, the chart shown in Figure 1 was obtained, and it was confirmed that it was aquakleptite. Example 2 Take 2.5 g of the gel solid content from which water has been evaporated from the pre-gel A prepared in Example 1, add 14 ml of 15% ammonia water, and mix uniformly.
When 10 such samples were prepared and reacted under the conditions described below, an X-ray powder diffraction pattern unique to aquakleptite was obtained for each sample. In addition, when heating using an autoclave, Example 1
When heating using a water bath, a 100 ml glass beaker was used, a plastic sheet was placed on top of the beaker to prevent water evaporation, and the beaker was sealed with a rubber band before heating.

[Table] Example 3 The pre-gel A slurry prepared in Example 1 was left for one week, and about 100 ml of it was taken, put into the autoclave used in Example 1, sealed, and incubated at 230°C for 7 days. After maintaining the temperature for several days, the powder inside was collected and subjected to X-ray powder diffraction analysis while still wet, which revealed a unique pattern of aquakleptite. The resulting aquakleptite was filtered and formed into a square plate of 1 cm in thickness and 5 mm in thickness. When this is left to air dry and then heated to 300℃, an aquakleptite plate is obtained with a shrinkage rate of about 20%. When this board was placed in water, it was observed to produce bubbles and crackle sounds, which are typical of aquakleptite. Example 4 The same reaction as in Example 2 was carried out after adjusting the pH to 10 using a caustic potassium aqueous solution and a caustic soda aqueous solution instead of aqueous ammonia. As a result of X-ray powder diffraction analysis, all of the obtained white powders had a pattern unique to aquakleptite.

[Table] Bath drying
12 NaOH 〃 〃 〃
〃
Example 5 Take 100 g of No. 3 water glass, add water to it under stirring to make 200 g of an aqueous solution, and then add H ⁺ type ion exchange resin (Amberlite WH, manufactured by Mitsubishi Chemical Industries, Ltd.) washed with hydrochloric acid. By passing it through the column for about 1 hour, a silica sol with a pH of about 6 is obtained. Gradually add 16ml of concentrated ammonia water to this,
After adjusting the pH of the sol to about 10, the PH of this sol should be adjusted to about 90.
Keep at ℃, evaporate the water, and prepare a silica sol with _SiO2 component of about 10%. Take 60g of this sol,
Add 4 g of magnesium oxide powder to this and mix until homogeneous using a household mixer to obtain a creamy gel of magnesium silicate. After leaving it for one week without evaporating the water, it was placed in the autoclave used in Example 1. Seal and 180~
After heating it to 200°C and continuing to heat it for 36 hours, when it was cooled, a paste-like substance had settled on the bottom and a layer of only water had formed on the top. Decantation was repeated several times to adjust the pH of the supernatant to 8, and the paste was filtered and dried to obtain white powdery crystals. When this material was subjected to X-ray powder diffraction, the diffraction intensity of (110) was weak, but it showed a characteristic X-ray powder diffraction pattern unique to aquakleptite. Example 6 Take 100g of No. 3 water glass and add water to it.
Make a 200g aqueous solution. Add this solution to 2N hydrochloric acid.
When the solution is gradually added dropwise into 100ml with stirring, a colorless and transparent silica sol containing sodium chloride is obtained. If you leave it for a day and night, a pudding-like silica hydrogel will form, so transfer this hydrogel to a large container filled with water and wash it with water all day and night.
After that, this hydrogel was taken out and the internal volume was
A silica sol is obtained by grinding in a 500 ml magnetic ball mill for about 3 hours. Add 9.6 g of magnesium hydroxide powder to this and mix with a magnetic ball for about 2 hours to obtain a white slurry-like magnesium silicate gel. The gel is taken out while being washed with water, and left to stand for a while to allow the gel to precipitate, and the upper supernatant liquid is removed by decantation. Leave it for about a week and repeat the decantation during that time.
About 100ml of magnesium silicate gel is obtained. This was placed in the autoclave used in Example 1, sealed, and heated at 150 to 180°C for about a week, cooled, the crystallized white part was separated, and heated to 100°C for 1 week.
After drying for a while, white powdery crystals are obtained. This is the same aquakleptite X as shown in Figure 1.
A line powder diffraction pattern is shown.

[Brief explanation of drawings]

FIG. 1 shows an X-ray powder diffraction pattern of artificial aquakleptite obtained by the present invention.

Claims (1)

[Claims] 1. A magnesium silicate gel is produced by mixing sol-like silicic acid and a magnesium compound in an atomic ratio of magnesium to silicon in the range of 0.48≦Mg/Si≦1, and the PH of this gel is A method for producing artificial aquakleptite, which comprises adjusting the temperature to 8 to 13.5, and then heating the mixture to approximately 80 to 350°C in the presence of water.