JP2002052337A - Air-conditioning material exhibiting excellent water absorption behavior at high-humidity - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air-conditioning material which exhibits an excellent water absorption behavior under high-humidity conditions, adsorbs water vapor in an amount of about 200% or higher of its own weight under high humidity conditions of a relative humidity of 90% or higher, can release the most part of adsorbed water vapor under normal humidity conditions of a relative humidity of 90% or lower, and can be repeatedly used. SOLUTION: This air-conditioning material comprises hollow fibrous aluminum silicate having minute mesopores with a pore radius lower than 5 nm. The method for producing an air-conditioning material exhibiting excellent adsorption behavior under high-humidity conditions comprises subjecting hollow fibrous aluminum silicate synthesized under weakly acidic conditions to hydrothermal synthesis, adding an alkali to the silicate to coagulate a gelatinous substance of the silicate, and drying the silicate at such a temperature as not to thermally decompose the fibers while utilizing a specific solid shape formed by the coagulation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a humidity control material exhibiting excellent water absorption behavior under high humidity conditions. More specifically, the present invention relates to a durable material comprising hollow fibrous aluminum silicate having specific mesopore pores. Excellent in nature,
The present invention relates to a novel humidity control material which is superior to existing dew condensation preventing materials from the viewpoint of energy saving, is useful as a dew condensation preventing material, and a method for producing the same.

[0002]

2. Description of the Related Art In recent years, buildings related to dwelling in Japan have been promoted to have high heat insulation and high airtightness, thereby causing internal dew condensation, accompanying wetness and stains on walls, and breeding of molds and mites. There is a problem. With such a change in living space, techniques for dew condensation prevention measures have become increasingly important. Conventionally, dew condensation has been prevented by using quicklime (calcium oxide), silica gel, or the like as a desiccant, or by operating an air conditioner such as a dehumidifier or an air conditioner.

However, all of the above desiccants have strong hygroscopicity, and it is difficult to control the dehumidifying ability. Further, once the saturation point is reached, the moisture absorption function is greatly reduced, so that the moisture absorption effective period is short. Furthermore, since it is not easy to separate the once absorbed moisture and restore the moisture absorbing function, it is difficult to repeatedly reuse the moisture. On the other hand, dehumidification by operation of an air conditioner such as a dehumidifier or an air conditioner is not preferable in terms of energy consumption and economy.

[0004]

Under these circumstances, the present inventors have developed a new humidity control material which can solve the problems of the conventional products in view of the above prior art. As a result of intensive research, hollow fibrous aluminum silicate with specific mesopore pores,
The present inventors have found that they exhibit excellent water absorption behavior under high humidity conditions, and have conducted further studies to complete the present invention. That is, the present invention can adsorb a large amount of water vapor under high humidity conditions, and can easily release most of the adsorbed water vapor under normal humidity conditions, and thereby can be used repeatedly to prevent 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 of manufacturing such a humidity control material relatively easily and at low cost.

[0005]

According to the present invention, there is provided a humidity control material comprising a porous tubular aluminum silicate having mesopore pores having a pore radius of less than 20 nm, wherein the relative humidity is 90%. % Adsorbs water vapor of more than about 200% of its own weight under high humidity conditions,
A humidity control material which can easily release most of the water vapor adsorbed under normal humidity conditions of about 90% or less relative humidity and which can be repeatedly used and which exhibits excellent water absorption behavior under high humidity conditions. Provided. Furthermore, after synthesizing hollow fibrous aluminum silicate synthesized under weakly acidic conditions by hydrothermal synthesis, an alkaline aqueous solution is added, and the entire solution including the product is made alkaline with a pH of about 8 to 12. By using the unique three-dimensional shape formed by agglomerating the product as a gel substance, it shows excellent water absorption behavior under high humidity conditions by drying at a temperature that does not itself thermally decompose A method for producing a humidity control material, characterized by obtaining a humidity control material.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. The method of the present invention is formed by hydrothermally synthesizing a hollow fibrous aluminum silicate synthesized under weakly acidic conditions and then adding an alkali to agglomerate the gel-like substance of the hollow fibrous aluminum silicate. It is characterized in that it is dried at a temperature at which it does not itself thermally decompose, utilizing a unique three-dimensional shape. As a result, under a high humidity condition of 90% or more of relative humidity, water vapor of about 200% or more of its own weight is adsorbed, and a relative humidity of 90% or more is absorbed.
The present invention provides a porous material exhibiting an excellent humidity control function that easily releases most of the adsorbed water vapor under ordinary humidity conditions of about% 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, specifically, sodium orthosilicate, sodium metasilicate,
Suitable examples include amorphous colloidal silicon dioxide (eg, Aerosil). The aluminum source to be bonded to the above-mentioned silicate molecule may be any aluminum ion, and specific examples include aluminum compounds such as aluminum chloride, aluminum nitrate, and aluminum perchlorate. These silicon source and aluminum source are not limited to the above-mentioned compounds, but may be used as long as they have the same effect.

[0008] These raw materials are dissolved in an appropriate aqueous solution,
Prepare a solution of the desired concentration. There is no problem in the formation of the precursor even if these solutions are mixed at an arbitrary ratio, but they are preferably mixed so that the silicon / aluminum ratio is 0.5 to 1.0. The concentration of the silicon compound in the solution is 1-1.
The concentration of the aluminum compound solution is 2,000 mmol / l and the concentration of the aluminum compound solution is 1 to 2000 mmol / l.
It is preferable to mix a 1000 mmol / l aluminum compound solution. After mixing the silicon compound solution with the aluminum compound solution, an alkaline solution is added dropwise, and the pH is adjusted from weakly acidic to near neutral to form a precursor. Examples of the alkaline solution required for the neutralization reaction in the precursor generation process include sodium hydroxide, potassium hydroxide, and ammonia. After precursor formation, centrifugation, filtration, membrane separation, etc., to remove coexisting ions in the solution, then, the recovered precursor is dispersed in pure water, and further, to suppress the generation of by-products,
Acid is added dropwise to obtain an acidic solution having a pH of 3 to 6. Preferably, the pH is 3.5 to 4.5. The acid used at this time includes, for example, hydrochloric acid, nitric acid, perchloric acid and the like.

The precursor dispersed in the acidic aqueous solution is heated for 2 days. The heating method and conditions may be, for example, heating using a mantle heater or an autoclave so that water does not evaporate, and the temperature range is 50 ° C to 1 ° C.
The temperature is 20 ° C., preferably around 100 ° C. After heating, add an alkaline aqueous solution to the aqueous solution containing the product and add p.
By making H alkaline to about 8 to 12, the product is aggregated as a gel substance. Examples of the alkali used at this time include ammonia, sodium hydroxide, potassium hydroxide and the like. Hollow fibrous aluminum silicate with a unique three-dimensional shape formed by intertwining the fibers by drying at a temperature that does not itself decompose after removing excess water by centrifugation Are separated and recovered. The drying temperature may be 350 ° C. or less at which the hollow fibrous aluminum silicate is not decomposed, and preferably 50 to 12 ° C.
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 comprising hollow fibrous aluminum silicate having mesopore pores having a pore radius of less than 5 nm according to the present invention has the following properties. It can adsorb water vapor of about 200% or more of its own weight under a high humidity condition of 90% or more of relative humidity, and can easily release most of the adsorbed water vapor under a humidity condition of 90% or less of relative humidity. It shows excellent water absorption behavior under high humidity conditions that can be used repeatedly.

[0010]

Next, the present invention will be described in detail with reference to examples, but the present invention is not limited to the examples. Example (1) Synthesis method 125 ml of an aqueous sodium orthosilicate solution diluted with pure water was prepared so that the SiO2 concentration became 100 mmol / l. Separately, 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 stirred with a magnetic stirrer. The silicon / aluminum ratio at this time is 0.67. Further, 22 ml of a 1N aqueous solution of sodium hydroxide was added dropwise to this mixed solution to adjust the pH to around 6. The precursor was recovered from this solution by centrifugation, and the precursor was further washed twice with pure water by centrifugation.
It was dispersed in ml of pure water. 1.2 ml of 5N hydrochloric acid is added to the solution in which the precursor is dispersed, and the pH is adjusted to about 4. This solution was heated at 100 ° C. for 2
Heated for days. After the completion of the heating, 50 ml of an aqueous solution containing the product was placed in a centrifugation cell, a few drops of 28% aqueous ammonia were added, and the mixture was shaken well and then centrifuged. The resulting gel-like product is dried in a dryer at 100 ° C. for about 2 hours.
Sun dried. The obtained sample was crushed in an agate mortar and used as a measurement sample for the following measurement.

(2) Results The obtained sample was identified by powder X-ray diffraction measurement.
The pore distribution was measured using a nitrogen adsorption method. The absorption / desorption characteristics are determined from the change in sample weight when the equilibrium state is reached by changing the water vapor pressure while keeping the temperature in the measurement system constant (25 ° C) using an automatic adsorption equilibrium measuring device. It was measured by a method for determining the amount of adsorption (gravimetric method). The amount of water vapor adsorption is
The ratio of the weight of the adsorbed water to the weight of the sample in a completely dry state is shown.
FIG. 1 shows a powder X-ray diffraction pattern of the sample obtained in the example. The diffraction pattern is 2θ = 4, 9.5, 14, 27,
It has a peak near 40 ° and shows an X-ray diffraction pattern unique to hollow fiber aluminum silicate. FIG. 2 shows a pore distribution curve of the sample obtained in the example. The pore distribution of the obtained sample shows a peak top at a pore radius of about 0.4 nm. Furthermore, the absorption and absorption of the sample obtained in the Examples
The release characteristics (adsorption isotherm) are shown in FIG. The adsorption isotherm of the obtained sample rises sharply at a relative humidity of about 90%, and it can be seen from the desorption isotherm that most of the water vapor adsorbed at a relative humidity of about 90% is released.

Comparative Example FIG. 4 shows the absorption / desorption characteristics of calcium oxide and silica gel (adsorption isotherm) conventionally used as a desiccant.
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 must be dried at a relative humidity of 20% or less when reused. Thus, it can be seen that both are unsuitable for dew condensation prevention applications that are repeatedly used.

[0013]

As described above, according to the method of the present invention,
1) Humidity control made of hollow fibrous aluminum silicate having a unique three-dimensional shape formed by intertwining fibers obtained by coagulation as a gel substance useful as a dew condensation preventing material and then drying. The material can be manufactured relatively easily and at low cost. 2) Because of the excellent moisture adsorption / desorption performance as described above, an extremely good dew condensation preventing function and a material that can be used repeatedly can be provided. The special effect that it can be performed is produced.

[Brief description of the drawings]

FIG. 1 shows the measurement results of an X-ray diffraction pattern of a material obtained in an example of the present invention.

FIG. 2 is a graph showing a pore distribution of a material obtained in an example of the present invention.

FIG. 3 is a graph showing a water vapor adsorption / desorption isotherm of a material obtained in an example of the present invention.

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

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification FI FI Theme Court ゛ (Reference) D01F 9/08 D01F 9/08 A (72) Inventor Masaki Maeda 54 Address (72) Inventor Shinji Watarimura 1-7-12 Minamigaoka, Chigusa-ku, Nagoya-shi, Aichi F-term (reference) 4D052 AA08 CE00 DA00 DB01 GA04 GB03 GB14 GB16 GB18 GB19 HA00 HB02 4G066 AA30A AA30B AA32A BA16 BA23 BA24 BA31 BA36 CA43 DA03 FA03 FA21 FA33 GA06 GA31 4G073 BA57 BA63 BD11 BD19 FC03 FD15 FD17 FD21 FE02 GA03 GA13 UA06 4L037 CS19 FA03 FA04 FA05 PA40 UA20

Claims (2)

[Claims] 1. A method in which a hollow fibrous aluminum silicate synthesized under weakly acidic conditions is synthesized by hydrothermal synthesis, and then an alkaline aqueous solution is added to make the entire solution containing the product alkaline. Agglomerated as a gel-like substance, obtained by drying at a temperature that does not itself thermally decompose, a moisture-conditioning material comprising hollow fibrous aluminum silicate having mesopore pores having a pore radius of less than 5 nm, Adsorbs water vapor of about 200% or more of its own weight under a high humidity condition of 90% or more of relative humidity, and has a relative humidity of 9% or more.
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 can be repeatedly used and has excellent water absorption behavior under high humidity conditions. 2. The method for producing a humidity control material according to claim 1, wherein a hollow fiber aluminum silicate synthesized under weakly acidic conditions is synthesized by hydrothermal synthesis, and then an alkaline aqueous solution is formed. In addition, by making the entire solution containing the product alkaline, the product is agglomerated as a gel substance, and then dried at a temperature that does not itself thermally decompose. A method for producing a humidity control material exhibiting excellent water absorption behavior under high humidity conditions, comprising obtaining a humidity control material comprising a fibrous aluminum silicate.