JPS6246491B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for producing a porous clay material having a pore diameter of 20 angstroms or more, and more specifically, a method for producing a porous clay material having a pore diameter of 20 angstroms or more, and more specifically, a method for producing a porous clay material having a pore size of 20 angstroms or more, and more specifically, a method for producing a porous clay material having a pore size of 20 angstroms or more. , relates to a method for producing a porous clay material in which the interlayer spacing is maintained at 20 angstroms or more.

Smectite-type minerals include montmorillonite, bentonite, chlorite, beidellite, hectorite, and synthetic mica. For example, in the crystal structure of montmorillonite, a silicate tetrahedral layer, an alumina octahedral layer, and a silicate tetrahedral layer are stacked and bonded to form a single crystal layer. In addition, aluminum, the central metal of the octahedral layer, is partially replaced by magnesium, which has a lower positive charge, which gives the layer a negative charge. Alkali metal ions (mainly Na ⁺ ) corresponding to this negative charge are interposed between the layers to neutralize the charge on the crystal layer. Therefore, montmorillonite has a large cation exchange capacity. Also, due to the hydration properties of the exchangeable cations, a significant amount of water is absorbed between the layers, resulting in extremely high swelling properties. Other smectite-type minerals also have properties similar to montmorillonite. Attempts have been made to use the above-mentioned smectite minerals as heat insulating materials, adsorbents, etc. by utilizing their interlayer structure.

Conventional porous clay materials, such as JP-A-54-5884
No. 54-16386 and JP-A No. 16386/1986, the material contains a cationic hydroxy metal complex, aluminum chlorohydroxide complex, silicate, phosphate, zirconia, etc. between the layers of a smectite mineral, and the interlayer spacing is approximately 10 angstroms or less.

However, when a smectite mineral with a short interlayer distance as described above is used as a heat insulating material, sufficient effects may not be obtained. For example, when this material is used to make insulation materials, the layers become clogged with water even at a relative humidity of about 10%. Therefore, a sufficient heat insulation effect cannot be achieved.

The present inventors first added a neutral water-soluble polymer compound, silica sol, a cation supplying substance, and water to a smectite mineral, mixed them thoroughly, and then dried them to create a pore size of 20 angstroms or more. However, as a result of further research, we have developed a method to obtain microporous clay with
It was discovered that a microporous clay material having a pore diameter of angstroms or more can be obtained, and the present invention was completed.

That is, this invention provides smectite minerals with
The present invention provides a method for producing a microporous clay material, which is characterized in that a neutral water-soluble polymer compound, silica sol, and water are added, thoroughly mixed, and then dried. A cross-sectional view of the structure of the microporous clay material of this invention is shown in FIG. a is a crystalline layer of smectite-type mineral, and its thickness _d1 is about 10 angstroms. Spirals and b are a neutral water-soluble polymer compound and silica inserted between the layers, and serve as pillars that support the interlayers. And an interlayer spacing of d ₂ appears. The microporous clay material of this invention has a d ₂ of 20 angstroms or more.

The smectite type mineral in this invention can be selected from, for example, montmorillonite, bentonite, chlorite, beidellite, hectorite, synthetic mica and substituted analogs thereof, or a mixture of two or more thereof.

Further, the neutral water-soluble polymer compound may be one having a neutral charge when dissolved in water, and for example, polyvinyl alcohol, polyethylene oxide, etc. are used.

As a result of examining the interlayer spacing of the microporous clay material of the present invention by a nitrogen adsorption/desorption method, as shown in FIG. 2, the interlayer spacing is mainly 20 angstroms or more and 60 angstroms or less. In addition, the surface area with an interlayer spacing of 20 angstroms or more is approximately 210 m ² /
g, total surface area is approximately 320 m ² /g, nitrogen capacity is approximately 0.21 ml/g, specific volume is approximately 0.61 cm ³ /g, porosity is approximately
It is 0.35.

Figure 3 shows the state when a smectite mineral is mixed with water, where a is the crystal layer and d ₁ is the thickness of the crystal layer (approximately 10 angstroms). The distance d ₃ changes depending on the mixing ratio of smectite minerals and water, and can take a maximum value of about 500 angstroms if a large amount of water is present. However, smectite minerals
When mixed with water containing cations such as Ca ²⁺ and Al ³⁺ , the positive charge between the layers increases and d ₃ decreases. And if the amount of cations increases, d ₃ will finally be about
It becomes 10 angstroms.

In the production of this invention, first, a smectite mineral, water, a neutral water-soluble polymer compound, and silica sol are mixed. The amount of water is smectite mineral 1
0.4ml or more per gram. Further, the concentration of the aqueous solution of the neutral water-soluble polymer compound is set within a range where the solution exhibits fluidity at a viscosity below the level where the solution slightly flows when tilted.
Silica sol is 0.05 per gram of smectite mineral.
If the amount is less than 0.05 g, the column will not be large enough to widen the interlayer gap, and if it is more than 1 g, the porosity will decrease, so it is disadvantageous to use it. The order of mixing may be either mixing a mixed aqueous solution of a neutral water-soluble polymer compound and silica sol with a smectite mineral, or mixing a silica sol with a mixture of a smectite mineral and a neutral water-soluble polymer compound aqueous solution. The state after mixing is shown in FIG. Here, C is silica sol. The silica sol used in this invention has negatively charged amorphous silica particles dispersed in water to form a colloid, and the particles have a spherical shape. -SiOH groups and -OH ^- ions exist on the surface of the particles, and an electric double layer is formed by the alkali ions added as a stabilizer, which is stabilized by repulsion between the particles. When the distance between particles becomes shorter due to drying, thickening, gelation, aggregation, etc. occur. When a gel is dried, it changes from a water-containing gel to a dry gel. combination) A strong dry gel solid is obtained.

The spiral line in FIG. 4 represents a neutral water-soluble polymer compound. In this state, the appearance of structural viscosity of the neutral water-soluble polymer compound causes the interlayer to expand.
To explain this in more detail, in general, in an aqueous polymer solution, as the molecular weight of the polymer increases and the concentration increases, the viscosity increases and becomes difficult to flow. This is due to the appearance of structural viscosity due to the formation of a network structure resulting from the so-called "entanglement" phenomenon in which polymer threads become entangled. Then, it begins to exhibit rubber elasticity.

The present invention is characterized in that the characteristics of these neutral water-soluble polymer compounds are applied to the interlayers of smectite minerals so that the interlayer distance does not become smaller due to the insertion of silica sol.

Next, water between the layers is removed by drying at room temperature or up to 200°C under the conditions shown in Figure 4.
The spread of neutral water-soluble polymer compounds becomes smaller,
Pillars of silica are formed between the layers (Figure 1).

Therefore, another feature of the present invention is to fix these neutral water-soluble polymer compounds and silica sol between the layers of smectite minerals, and then dry them to create a microporous clay material of smectite minerals with long interlayer distances. It is at the point where it can be obtained.

These microporous clay materials, when oriented, are useful in high performance insulation materials.

Examples of this invention will be shown below.

Example 1 Polyethylene oxide with a degree of polymerization of 39,000 to 50,000
Dissolve 0.036g in 9ml of water. 31 in 9 ml of dissolved 0.4 weight percent polyethylene oxide aqueous solution.
Add 0.9 ml of a weight percent silica sol aqueous solution (SI-350, manufactured by Catalysts Kasei Kogyo), and stir and mix.
Sodium montmorillonite 1.00 into mixed aqueous solution
After further stirring and mixing, the mixture was left to dry in a dryer at 50°C for 2 days. As a result of investigating the pore size, surface area, nitrogen capacity, specific volume, and porosity of the product using the nitrogen adsorption/desorption method, the pore size at which the pore distribution peaks is 31 angstroms, and the surface area is 170 m for pore diameters of 20 angstroms or more. The total surface area was 247 ^{m 2} /g, the nitrogen capacity was 0.17 ml/g, the specific volume was 0.57 cm ³ /g, and the porosity was 0.29.

Example 2 Polyethylene oxide with a degree of polymerization of 39,000 to 50,000
Dissolve 0.073g in 18ml of water. 31 in 18 ml of dissolved 0.4 weight percent polyethylene oxide aqueous solution
Add 1.8 ml of a weight percent silica sol aqueous solution (SI-350, manufactured by Catalysts Kasei Kogyo), and stir and mix.
Sodium montmorillonite 1.00 into mixed aqueous solution
After further stirring and mixing, the mixture was left to dry in a dryer at 50°C for 2 days. As a result of investigating the pore size, surface area, nitrogen capacity, specific volume, and porosity of the product using the nitrogen adsorption/desorption method, the pore size at which the pore distribution peaks is 31 angstroms, and the surface area is 211 m for pore diameters of 20 angstroms or more. The total surface area was 321 ^{m 2 /} g, the nitrogen capacity was 0.21 ml/g, the specific volume was 0.61 cm ³ /g, and the porosity was 0.35.

[Brief explanation of the drawing]

FIG. 1 shows a cross-sectional view of the structure of the microporous clay material of the present invention. FIG. 2 is a pore distribution curve obtained by the nitrogen adsorption/desorption method of the microporous clay material of the present invention.
Figure 3 shows a smectite-type mineral in a swollen state containing water between its layers. FIG. 4 shows the state before drying in a production method in which a neutral water-soluble polymer compound and silica sol are inserted between layers of smectite minerals.

Claims (1)

[Claims] 1. A method for producing a microporous clay material, which comprises adding a neutral water-soluble polymer compound, silica sol, and water to a smectite mineral, mixing thoroughly, and then drying.