JP3398761B2 - Humidity control material showing excellent water absorption behavior under high humidity conditions - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a humidity control material which exhibits excellent water absorption behavior under high humidity conditions, and more specifically, it is composed of a hollow fibrous aluminum silicate having specific mesopore pores and is durable. Excellent in
The present invention relates to a novel humidity control material which is superior to existing dew condensation prevention materials from the viewpoint of energy saving and is useful as a dew condensation prevention material and the like, and a manufacturing method thereof.

[0002]

2. Description of the Related Art In recent years, buildings related to housing in Japan have been promoted to have high heat insulation and airtightness so that internal dew condensation may occur, resulting in wetting of wall surfaces and stains, and breeding of mold and mites. There is a problem. With such changes in living space, the technology for preventing dew condensation is becoming more important. Conventionally, quick lime (calcium oxide), silica gel, or the like is used as a desiccant, or dehumidifiers are prevented by operating air-conditioning equipment such as a dehumidifier and an air conditioner.

However, each of the above desiccants has a strong hygroscopic force, and it is difficult to control the dehumidifying ability. Further, once the saturation point is reached, the moisture absorption function is significantly reduced, so that the moisture absorption effective period is short. Furthermore, since it is not easy to separate the water once absorbed and restore the moisture absorption function, it is difficult to reuse it repeatedly. On the other hand, dehumidification by operating an air conditioner such as a dehumidifier or an air conditioner is not preferable in terms of energy consumption and economical efficiency.

[0004]

Under these circumstances, the inventors of the present invention, in view of the above-mentioned prior art, aim to develop a new humidity control material capable of solving the problems of the above-mentioned conventional products. As a result of accumulating extensive research as a hollow fiber aluminum silicate having specific mesopore pores,
The inventors have found that they exhibit excellent water absorption behavior under high humidity conditions, and have conducted further research to complete the present invention. That is, the present invention is capable of adsorbing a large amount of water vapor under high humidity conditions and easily releasing most of the adsorbed water vapor under normal humidity conditions, thereby enabling repeated use and prevention of dew condensation. It is an object of the present invention to provide a humidity control material that can be suitably used as a material, and a method that can manufacture such a humidity control material relatively easily and at low cost.

[0005]

In order to solve the above problems, the present invention provides a humidity control material comprising a porous tubular aluminum silicate having mesopore pores having a pore radius of less than 20 nm and having a relative humidity of 90. Adsorbs about 200% or more of water vapor of its own weight under high humidity conditions of
In addition, a humidity control material which can easily release most of the adsorbed water vapor under a normal humidity condition of about 90% or less of relative humidity and which can be repeatedly used and exhibits excellent water absorption behavior under a high humidity condition, Provided. Furthermore, after synthesizing hollow fibrous aluminum silicate synthesized under weakly acidic conditions by hydrothermal synthesis, an alkaline aqueous solution is added to make the entire solution containing the product alkaline with a pH of about 8-12. Exhibits a superior water absorption behavior under high humidity conditions by utilizing a unique three-dimensional shape formed by aggregating the product as a gel-like substance and drying it at a temperature at which it does not thermally decompose itself. A method for producing a humidity control material, which comprises obtaining the humidity control material.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in more detail below. The method of the present invention is formed by hydrothermally synthesizing hollow fibrous aluminum silicate synthesized under a weakly acidic condition, and then adding alkali to agglomerate the hollow fibrous aluminum silicate gel substance. The peculiar three-dimensional shape described above is utilized, and the drying is performed at a temperature at which it does not thermally decompose. As a result, under high humidity conditions of 90% relative humidity or more, about 200% or more of water vapor of its own weight is adsorbed, and relative humidity of 90% or more.
Provided is a porous material exhibiting an excellent humidity control function that easily releases most of the adsorbed water vapor under a normal humidity condition of about 10% or less.

In the method of the present invention, a silicon compound and an aluminum compound are used as raw materials. The reagent used as the silicon source may be monosilicic acid, and specifically, sodium orthosilicate, sodium metasilicate,
Amorphous colloidal silicon dioxide (such as Aerosil) is preferable. Further, the aluminum source to be bonded to the silicic acid molecules may be any aluminum ion, and specific examples thereof include aluminum compounds such as aluminum chloride, aluminum nitrate, and aluminum perchlorate. These silicon source and aluminum source are not limited to the above compounds, and may be similarly used as long as they have the same effect.

These raw materials are dissolved in an appropriate aqueous solution,
Prepare a solution of a given concentration. There is no problem in forming the precursor even if these solutions are mixed in an arbitrary ratio, but preferably they are mixed so that the silicon / aluminum ratio is 0.5 to 1.0. The concentration of the silicon compound in the solution is 1 to 1
The concentration of the aluminum compound solution is 1 to 2000 mmol / l at 000 mmol / l, but the preferable concentration is 1 to 500 mmol / l of the silicon compound solution and 1 to 500 mmol / l.
It is preferable to mix an aluminum compound solution of 1000 mmol / l. After the silicon compound solution is mixed with this aluminum compound solution, an alkaline solution is added dropwise to adjust the pH so as to be slightly acidic to near neutral to form a precursor. Examples of the alkaline solution necessary for the neutralization reaction in the precursor formation process include sodium hydroxide, potassium hydroxide, ammonia and the like. After the precursor is formed, the coexisting ions in the solution are removed by centrifugation, filtration, membrane separation, etc., and then the recovered precursor is dispersed in pure water to further suppress the production of by-products.
Acid is added dropwise to obtain an acidic solution having a pH of 3-6. The pH is preferably 3.5 to 4.5. In addition, examples of the acid used at this time include hydrochloric acid, nitric acid, perchloric acid and the like.

The precursor dispersed in this acidic aqueous solution is heated for 2 days. The heating method and conditions may be, for example, using a mantle heater or an autoclave so that the water does not evaporate, and the temperature range is 50 ° C to 1 ° C.
The temperature is 20 ° C., but preferably about 100 ° C. is desirable. After heating, add an alkaline aqueous solution to the aqueous solution containing the product.
By making H alkaline to about 8 to 12, the product is aggregated as a gel-like substance. Examples of the alkali used at this time include ammonia, sodium hydroxide, potassium hydroxide and the like. A hollow fibrous aluminum silicate having a peculiar three-dimensional shape formed by intricately entangled fibers by removing excess water by centrifugation and then drying at a temperature at which it does not thermally decompose. Are separated and collected. The drying temperature may be 350 ° C. or lower at which the hollow fibrous aluminum silicate is not decomposed, and preferably 50 to 12
It is 0 ° C. By the above method, a hollow fibrous aluminum silicate having mesopore pores having a pore radius of less than 5 nm can be obtained. The humidity control material of the present invention made of hollow fibrous aluminum silicate having mesopore pores having a pore radius of less than 5 nm has the following characteristics. It is possible to adsorb about 200% or more of its own weight of water vapor under high humidity conditions of 90% or more relative humidity, and to easily release most of the adsorbed water vapor under humidity conditions of 90% or less relative humidity. It exhibits excellent water absorption behavior under high humidity conditions where it can be used repeatedly.

[0010]

EXAMPLES Next, the present invention will be specifically described based on examples, but the present invention is not limited to the examples. Example (1) Synthetic method 125 ml of an aqueous solution of sodium orthosilicate was diluted with pure water so that the SiO2 concentration was 100 mmol / l. Separately from this, aluminum chloride was dissolved in pure water to prepare 125 ml of a 150 mmol / l aqueous solution. An aqueous solution of sodium orthosilicate was mixed with the aqueous solution of aluminum chloride, and the mixture was stirred with a magnetic stirrer. At this time, the silicon / aluminum ratio is 0.67. Furthermore, 22 ml of a 1N sodium hydroxide aqueous solution was added dropwise to this mixed solution to adjust the pH to around 6. The solution was centrifuged to collect the precursor, and the precursor was washed twice with pure water by centrifugation to obtain 1000
Dispersed in ml of pure water. To the solution in which the precursor is dispersed, 1.2 ml of 5N hydrochloric acid is added to adjust the pH to around 4. This solution is heated with a mantle heater at 100 ° C for 2
Heated for days. After completion of heating, 50 ml of an aqueous solution containing the product was placed in a centrifuge cell, a few drops of 28% ammonia water was added, and the mixture was shaken well and then centrifuged. The gel-like product thus obtained was dried in a dryer at 100 ° C. for about 2 minutes.
Day dried. The obtained sample was crushed in an agate mortar and used as the measurement sample for the following measurement.

(2) The resulting sample was identified by powder X-ray diffraction measurement.
The pore distribution was measured using the nitrogen adsorption method. In addition, the absorption and desorption characteristics are measured from the change in the sample weight when the equilibrium state is reached by changing the water vapor pressure with the temperature inside the measurement system kept constant (25 ° C) using the adsorption equilibrium automatic measurement measuring device. The adsorption amount was measured by a method (gravimetric method). The amount of water vapor adsorption is
The ratio of the weight of adsorbed water to the weight of the sample in the absolutely dry state is shown.
The powder X-ray diffraction pattern of the sample obtained in the example is shown in FIG. The diffraction pattern is 2θ = 4, 9.5, 14, 27,
It has a peak near 40 ° and shows an X-ray diffraction pattern peculiar to hollow fiber aluminum silicate. The pore distribution curve of the sample obtained in the example is shown in FIG. The pore distribution of the obtained sample shows a peak top at a pore radius of about 0.4 nm. Furthermore, the absorption of the sample obtained in the example
The release characteristics (adsorption isotherm) are shown in FIG. The adsorption isotherm of the obtained sample rapidly rises at a relative humidity of about 90%, and it can be seen from the desorption isotherm that most of the adsorbed water vapor is released at a relative humidity of about 90%.

Comparative Example FIG. 4 shows the absorption and desorption characteristics (adsorption isotherm) of calcium oxide and silica gel, which have been conventionally used as desiccants.
Show. Calcium oxide changes to calcium hydroxide after absorbing water, and is difficult to reuse by drying. Also,
Silica gel is saturated at a relative humidity of 70% and needs to be dried at a relative humidity of 20% or less before reuse. Thus, it can be seen that neither of them is suitable for the purpose of preventing dew condensation that is repeatedly used.

[0013]

As described above, according to the method of the present invention,
1) Humidity control consisting of hollow fibrous aluminum silicate having a peculiar three-dimensional shape formed by intricately interlocking fibers obtained by aggregating as a gel substance useful as a dew condensation preventing material and then drying. It is possible to manufacture the material relatively easily and at low cost. 2) Since it has the excellent moisture adsorption / desorption performance as described above, it provides an extremely good dew condensation prevention function and a material that can be repeatedly used. The special effect of being able to do is exhibited.

[Brief description of drawings]

FIG. 1 shows the measurement results by X-ray diffraction pattern of the materials obtained in the examples of the present invention.

FIG. 2 is a graph showing the pore distribution of the materials obtained in the examples of the present invention.

FIG. 3 is a graph showing water vapor adsorption / desorption isotherms of the materials obtained in the examples of the present invention.

FIG. 4 is a graph showing adsorption / desorption isotherms of water vapor of a conventional hygroscopic material (desiccant) presented in a comparative example of the present invention.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification symbol FI D01F 9/08 D01F 9/08 A (72) Inventor Shinji Watamura 1-7-12 Minamigaoka, Chikusa-ku, Nagoya-shi, Aichi ( 56) References JP 10-309458 (JP, A) JP 9-294931 (JP, A) JP 2000-189744 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB) (Name) B01J 20/00-20/34 E04B 1/64

Claims (2)

(57) [Claims] 1. A product obtained by hydrothermally synthesizing hollow fiber aluminum silicate synthesized under a weakly acidic condition and then adding an alkaline aqueous solution to make the entire solution containing the product alkaline. Which is a gel-like substance, and is dried at a temperature at which it does not thermally decompose itself, and is a humidity control material comprising hollow fibrous aluminum silicate having mesopore pores with a pore radius of less than 5 nm. Adsorbs about 200% or more of its own weight of water vapor under high humidity conditions of 90% or more relative humidity, and
A humidity control material that can easily release most of the adsorbed water vapor under a humidity condition of about 0% or less and that exhibits excellent water absorption behavior under high humidity conditions, which can be repeatedly used. 2. The method for producing the humidity control material according to claim 1, wherein the hollow fibrous aluminum silicate synthesized under a weakly acidic condition is synthesized by hydrothermal synthesis, and then an alkaline aqueous solution is added. In addition, by making the entire solution containing the product alkaline, the product is aggregated as a gel-like substance and then dried at a temperature at which it does not decompose by itself. A method for producing a humidity control material exhibiting excellent water absorption behavior under high humidity conditions, which comprises obtaining a humidity control material made of fibrous aluminum silicate.