JPH044274B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field] The present invention relates to a method for producing an inorganic layered porous body with excellent heat insulation properties. [Background Art] As a layered porous material that forms voids, there is an intercalation material in which a different substance such as hydroxide is inserted and reacted between layers of a swellable layered compound (for example, Japanese Patent Laid-Open No. 54-5884 and Japanese Unexamined Patent Publication 1973-
(See Publication No. 16386). However, since this material has a small interlayer distance of 10 Å or less, it is easily affected by adsorbed water, and it cannot be said to have very good thermal insulation properties. On the other hand, it has been proposed in Japanese Patent Publication No. 2006-11111 to use a mixture of smectite minerals and water-soluble polymer compounds as a microporous clay material, and intercalate the mixture with cationic oxides or polymeric silica. Publication No. 131878, 1984, Japanese Patent Application Publication No. 1983-
Publication No. 137812, Japanese Unexamined Patent Publication No. 137813, Japanese Unexamined Patent Publication No. 1983-137813
Publication No. 60-155526 and JP-A-60-166217
It is shown in the publication number etc. According to these methods, the interlayer distance can be increased from 10 Å or less in the case of the above-mentioned intercalation material to about 30 Å. However, in the layered porous material formed by this method, even if the interlayer distance can be increased to about 30 Å as described above, water is likely to be adsorbed within the voids. The occurrence of thermal short circuits between layers is unavoidable, and improvement in thermal properties cannot be expected. [Object of the Invention] In view of the above circumstances, an object of the present invention is to provide a method for producing an inorganic layered porous body having relatively large voids between layers and having an excellent heat insulating effect. [Disclosure of the invention] In order to achieve the above object, this invention
At least one of a water-soluble polymer compound and a quaternary ammonium salt is inserted between the layers of the swollen layered compound, and a silica sol whose surface has been previously treated with a silane coupling agent is also inserted between the layers. The gist of this invention is a method for producing an inorganic layered porous body which is dried and fired to form fine voids between the layers. Hereinafter, the present invention will be explained in detail with reference to the drawings showing one embodiment thereof. As shown in FIG. 1, which schematically shows the structure, the inorganic layered porous material A obtained by the method for producing an inorganic layered porous material of the present invention has silica 2 between the layers 1 and 1 of the inorganic layered compound. Insertion is fixed. Therefore, the gap 3 between the layers is maintained at 30 to 600 Å. Swellable layered compounds include Na-montmorillonite, Ca-montmorillonite, acid clay, 3
- Octahedral synthetic smectite, Na-hectite,
Examples include Li-hectorite, Na-teniolite, Li-teniolite, and synthetic mica (Na-fluorine-tetrasilicon mica), but the compound is not limited to these as long as it is a swellable layered compound.
When using a swellable layered compound such as Ca-montmorillonite or acid clay as the main material, it is difficult to swell unless strong shearing force is applied.
It is necessary to knead during swelling. The type of silane coupling agent for treating the surface of the silica sol is not particularly limited in this invention, but for example, compounds represented by the following formula () are preferred for this invention. RSiX ₃ ...() In the formula, R represents an organic functional group having a substituent that binds to an organic material, and preferred examples include an amino group, a vinyl group, and an epoxy group. Further, in the formula, X represents a hydrolyzable group that reacts with an inorganic material, and preferable examples include halogens such as Cl and F, and alkoxy groups such as methoxy and ethoxy groups. In this invention, the reason why the surface of the silica gel is pretreated with the silane coupling agent as described above is as follows. In other words, silica gel usually has a negatively charged surface, so this
If used as is, it would be difficult to insert it between the layers 1 and 1, which are also negatively charged. However, when the surface of such silica sol is treated with the silane coupling agent, the surface of the silica gel becomes a treated product 2' with a positive charge, thereby causing the layers 1, 1 to
This makes it easy to insert it between the two. Various water-soluble polymer compounds can be considered, but preferred examples include polyvinyl alcohol, polyethylene glycol, polyethylene oxide, methylcellulose, carboxymethylcellulose, sodium polyacrylate, and polyvinylpyrrolidone. In addition, various quaternary ammonium salts can be considered, among which octadecyl group,
Those having groups such as hexadecyl group, tetradecyl group and dodecyl group are preferred. Examples of such quaternary ammonium salts include the following compounds, but as long as they help insert silica sol by expanding the interlayer space and are vaporized by firing to leave voids between the layers, these compounds can be used. You can also use something else. Octadecyltrimethylammonium salt, octadecyldimethylammonium salt, hexadecyltrimethylammonium salt, tetradecyltrimethylammonium salt, tetradecylmethylammonium salt. Next, regarding the manufacturing method of this inorganic layered porous material,
One embodiment will be explained in detail based on the drawings schematically showing one embodiment. Materials such as swellable clay minerals are made up of a collection of swellable layered compounds _A1 , as shown in Figure 2. As shown in Figure 3, the main material compound A ₁ is mixed with a solvent such as water (kneaded if necessary).
Solvent 4 is impregnated between layers 1 and 1 to swell them in advance. Water is generally used as the solvent, but other polar solvents such as methanol, DMF, and DMSO may be used alone or in combination. Next, the surface of the silica sol is treated with a silane coupling agent. Through this process, FIG.
As shown in the figure, a treated product 2' with a positively charged surface is obtained. To the processed material 2′ created in this way,
At least one of the water-soluble polymer compound and the quaternary ammonium salt is blended as a soft pillar 5, and mixed until sufficiently uniform as shown in FIG. 4b. The resulting mixture is mixed with the swellable layered compound that has been swollen in advance and inserted between layers 1 and 1 of the layered compound as shown in FIG. 5 (intercalation). Then, the water-soluble polymer compound and quaternary ammonium salt serve as soft pillars 5 to spread and hold the space between the layers 1 and 1, and at the same time, to slow down the movement of the material 2' and hold it between the layers. do. It is thought that the positive charge on the surface of the retained treated material 2' electrically couples with the negative portion on the surface of layer 1, thereby expanding and holding the space between layers 1 and 1. . The temperature during mixing is preferably around 60 to 70°C. This reaction solution is centrifuged to dehydrate it, and then oriented into a plate shape using a spatula or the like. This plate material
After drying by hot air drying etc. at a temperature of about 60℃, further drying at 300 to 600℃, preferably 450 to 550℃
Fire it with By this calcination, the water-soluble polymer compound and quaternary ammonium salt are converted into CO ₂ , NH ₃ ,
They are converted into H ₂ O, etc. and removed, and the spaces where these existed remain as voids 3 to obtain a plate-shaped inorganic layered porous material with silica 2 inserted between the layers, as shown in Figure 1. I can do it. The inorganic layered porous material thus obtained has a layer spacing of 30 to 600 Å in more than 40% of the total, and has excellent heat insulation properties in the direction of arrow B in FIG. Note that in the above examples, the silica gel and the soft pillars are mixed and then inserted between the layers of the swellable layered compound, but it seems that they are inserted separately into the interlayers. It doesn't matter. Examples will be described in detail below. Example 1 Na-montmorillonite (Kunipia F, manufactured by Kunimine Kogyo Co., Ltd.) was prepared as a swellable layered compound, and was previously dispersed in water to obtain an aqueous solution.
Next, a 10% by weight aqueous solution of silica sol (Snowtex CK-XS, manufactured by Nissan Chemical Industries, Ltd.) whose surface was treated with an aminosilane coupling agent was prepared, and a water-soluble polymer compound was added to it as a soft pillar. Polyvinyl alcohol with a molecular weight of 22,000 was added and thoroughly mixed to obtain a mixture. The resulting mixture was put into a flask together with the aqueous solution, mixed, stirred thoroughly, and subjected to an insertion reaction at a temperature of 60° C. for 90 minutes. The compounding ratio of each is expressed as a weight ratio.
The ratio of Na-montmorillonite:water:silica sol:polyvinyl alcohol was 1:125:6:0.1.
After the insertion reaction, this was centrifuged, oriented in a plate shape with a spatula, and dried with warm air at a temperature of 60°C. This was placed in an electric furnace and fired at 450°C to obtain a plate-like inorganic layered porous material sample with a thickness of 1.5 mm. Example 2 A plate-like inorganic material was prepared in the same manner as in Example 1, except that octadecyltrimethylalmonium chloride (Nitsusan Cation AB, Nippon Oil & Fats Co., Ltd., 23% by weight aqueous solution), which is a quaternary ammonium salt, was used as the soft pillar. A layered porous material sample was obtained. The respective compounding ratios are Na-montmorillonite:water:
Silica sol: Quaternary ammonium salt = 1:125:
6:4.4. Example 3 Compounding ratio of Na-montmorillonite by weight:
Water: Silica gel: Quaternary ammonium salt = 1:
A plate-like inorganic layered porous material sample was obtained in the same manner as in Example 2, except that the ratio was 10:6:4.4 and the reaction was carried out in a universal mixer. Example 4 As a soft pillar, a mixture of two quaternary ammonium salts, octadelcyltrimethylammonium chloride and hexadecyltrimethylammonium chloride (Alucard 2HT-72 manufactured by Lion Yushi Co., Ltd., the mixing ratio was A plate-like inorganic layered porous material sample was obtained in the same manner as in Example 2 except that octadecyl:hexadecyl=75:24) was used. The blending ratio was Na-montmorillonite:water:silica gel:quaternary ammonium salt=1:125:6:1 by weight. Example 5 A plate-shaped inorganic layered porous material sample was obtained in the same manner as in Example 2, except that synthetic mica (Dimonite HG, manufactured by Topy Chemical Industries, Ltd.) was used as the swelling layered compound.
The mixing ratio of each component is synthetic mica: water: silica gel: quaternary ammonium salt = 1:125:6:
It was 4.4. Comparative Example 1 Colloidal silica whose surface was not treated with a silane coupling agent (average particle size 130 Å,
20% aqueous solution) as a swellable layered compound.
Sodium-montmorillonite (Kunipia F manufactured by Kunimine Kogyo Co., Ltd.) was used, and this was combined with polyethylene oxide, a water-soluble polymer compound (Arcotox E75 manufactured by Meisei Chemical Co., Ltd., with an average molecular weight of 150,000 to 220
10,000) and water at 70°C for 40 minutes. After drying, orient this mixture into a plate shape using a spatula, etc.
Firing was performed at 400°C for 2 hours to obtain a plate-shaped molded body sample. The blending ratio of Na-montmorillonite, water, colloidal silica, and polyethylene oxide is as follows:
The weight ratio was 1:10:3:0.1. The porosity of the molded body samples obtained in these Examples,
The interlayer distance, density, and thermal conductivity were measured, and the results were combined with the results of three comparative examples: a molded body sample made of an inorganic layered porous material obtained by a known method, a gypsum board, and a molded body of sand. It is shown in Table 1. The porosity is determined by the following formula: Porosity = [Surface area of sample] - [Surface area of inorganic compound between layers] - [Outer surface area of layered compound in sample] / [Weight of layered compound in sample] × [Theoretical specific surface area when all layers of the layered compound are open] The specific surface area was obtained using the BET method in the nitrogen adsorption method, and the average interlayer distance (pore distribution) was obtained using the CI method in the nitrogen adsorption method. The nitrogen adsorption device used was Autosoap 6 manufactured by Quantachrome. The thermal conductivity measurement was performed using a thermal conductivity measurement device using the xenon brush method.

【table】

〔Effect of the invention〕

Since the manufacturing method of the inorganic layered porous material of the present invention is configured as described above, the layer spacing of 40% or more of the whole is maintained at 30 to 600 Å by the inorganic compound, and the porosity is increased to 30% or more. It becomes possible to reliably obtain an inorganic layered porous material which has a low thermal conductivity and has excellent heat insulating properties that are useful for heat insulating materials and the like.

[Brief explanation of drawings]

Figure 1 is a schematic side view of an inorganic layered porous material, Figure 2 is a schematic side view of an inorganic layered porous material;
The figure is a schematic side view of the swellable layered compound, Figure 3 is an explanatory diagram illustrating the state leading to swelling, and Figure 4 a.
is an explanatory diagram illustrating the state in which the surface of the silica sol has been treated with a silane coupling agent, FIG. FIG. 3 is an explanatory diagram illustrating a state in which the mixture of FIG. b is inserted between layers of a swellable layered compound. A...Inorganic layered porous material, _A1 ...Swellable inorganic layered compound, 1...Layer, 2...Silica, 3...Void, 5...Soft pillar.

Claims (1)

[Scope of Claims] 1. A silica sol in which at least one of a water-soluble polymer compound and a quaternary ammonium salt is inserted between the layers of a swollen layered compound, and the surface of which has been previously treated with a silane coupling agent. A method for producing an inorganic layered porous body, which comprises also inserting a material between the layers, and drying and firing the material to form fine voids between the layers. 2 A compound in which the silane coupling agent is represented by the following formula (), RSiX ₃ ... () [However, R represents an organic functional group having a substituent that bonds with an organic material, and X reacts with an inorganic material. Represents a hydrolyzable group. ] A method for producing an inorganic layered porous material according to claim 1. 3. Claim 1, wherein the water-soluble polymer compound is at least one compound selected from the group consisting of polyvinyl alcohol, polyethylene glycol, polyethylene oxide, methylcellulose, carboxymethylcellulose, sodium polyacrylate, and polyvinylpyrrolidone. A method for producing an inorganic layered porous material according to item 1 or 2. 4 The quaternary ammonium salt has an octadecyl group,
4. The method for producing an inorganic layered porous material according to any one of claims 1 to 3, which has at least one group selected from the group consisting of a hexadecyl group, a tetradecyl group, and a dodecyl group. 5 Swelling layered compounds include Na-montmorillonite, Ca-montmorillonite, acid clay, 3-octahedral synthetic smectite, Na-hectrite, Li
- The method for producing an inorganic layered porous material according to any one of claims 1 to 4, which is at least one selected from the group consisting of hectorite, Na-teniolite, Li-teniolite, and synthetic mica. 6 Claim 1 in which the void is 30 to 600 Å
A method for producing an inorganic layered porous material according to any one of Items 1 to 5.