JP2000189789A - Moisture regulating material usable repeatedly and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the moisture regulating material useful as the repeatedly usable moisture regulating material for dew condensation regulation and to provide its production method. SOLUTION: The composite of a porous metal hydroxide and a by-product having hydroscopicity is produced, by precipitating a metal hydroxide by adjusting the hydrogen ion concn. of a metal chloride aq. soln. with ammonia water, etc., and subjecting the hydroxide gel obtained by agitating the hydroxide in a hot water bath to heat treatment at the temp. at which a hygroscopic by-product is not thermally decomposed. In this way, the moisture regulating material for dew condensation usable repeatedly by absorbing the water vapor more than 60% of one's weight under the high humidity condition of >=80% relative humidity and easily releasing the water vapor under the usual humidity condition of <=60% relative humidity is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD [0001] The present invention is excellent in durability,
The present invention relates to a novel humidity control material useful as an anti-condensation material and the like, which is superior to existing anti-condensation materials, from the viewpoint of energy saving and reduction of environmental load, and a method for producing the same.

[0002]

2. Description of the Related Art In conventional Japanese houses, building materials such as wood and earth walls have been used. These materials themselves have humidity control performance, but the construction method itself has low airtightness in consideration of summer heat during high temperature and high humidity. However, in recent years, new construction materials with poor humidity control have been used extensively, and due to the promotion of high insulation and high airtightness, the occurrence of internal dew condensation, the resulting wetting of walls and generation of spots, and the propagation of mold and mites And other problems. With such a change in living environment, the importance of technology for preventing dew condensation is only increasing. 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.

[0003]

All of the above desiccants have a 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 and an air conditioner is not preferable in terms of energy consumption and economy.

[0004] It is therefore an object of the present invention to absorb large amounts of water vapor under high humidity conditions and to easily release most of the adsorbed water vapor under normal humidity conditions, thereby making it possible to use repeatedly. It is an object of the present invention to provide a humidity control material that can be suitably used as an anti-condensation prevention material and the like, and a method of manufacturing such a humidity control material relatively easily and at low cost.

[0005]

According to the present invention, a metal hydroxide is precipitated by adjusting the hydrogen ion concentration of an aqueous metal chloride solution with an aqueous ammonia solution. A composite of a porous metal hydroxide and a hygroscopic ammonium chloride is produced by heat-treating a hydroxide gel obtained by stirring in a solution at a temperature at which a hygroscopic by-product is not thermally decomposed. A method for producing a humidity control material is provided. Furthermore, according to the present invention, a composite of a porous metal hydroxide having mesopore pores having a pore radius of less than 10 nm and a hygroscopic substance, and 60% or more of its own weight under a high humidity condition of 80% or more in relative humidity. And a reusable humidity control material capable of easily releasing most of the adsorbed water vapor under normal humidity conditions of about 60% or less relative humidity.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The method of the present invention is intended to positively complex a hygroscopic substance by-produced when a metal hydroxide is precipitated from an aqueous metal chloride solution. And heat-treating at a temperature at which the hygroscopic by-product is not thermally decomposed. As a result, according to the present invention, a composite of a porous metal hydroxide and a hygroscopic substance is used, and the capillary condensation phenomenon of the porous metal hydroxide and the hygroscopic property of the coexisting hygroscopic substance are used together, Absorbs water vapor in the air in a humidity environment of 80% or more, and has a relative humidity of 6%.
A porous material having an excellent humidity control function of releasing water vapor in a humidity environment of about 0% or less is provided.

Hereinafter, the present invention will be described in more detail. The aqueous metal chloride solution used as a raw material in the method of the present invention includes an aluminum chloride aqueous solution and the like, as long as it can precipitate as a hydroxide by adjusting the hydrogen ion concentration. The regulator of the hydrogen ion concentration need only be one that does not interfere with the precipitation of hydroxide due to complex ion formation or the like.
Preferably, the by-product is not removed during the heat treatment, and the by-product has an appropriate hygroscopicity. More specifically, in the case of the above chloride aqueous solution, an aqueous ammonia solution is exemplified as a preferable one. After adding an appropriate regulator of hydrogen ion concentration to the aqueous metal chloride solution to adjust the hydrogen ion concentration at which hydroxides are precipitated, an appropriate method such as stirring in a warm water bath of less than 100 ° C. To prepare a gel in which the metal hydroxide is uniformly dispersed. After drying this gel in an appropriate method, for example, in a thermostat at about 100 ° C., the gel is maintained at a predetermined temperature for an appropriate time to cause a dehydration reaction to form a porous hydroxide. As heating conditions, only desorption of structural water occurs,
The heating is performed at a temperature not higher than the temperature at which by-products having hygroscopicity are not removed by thermal decomposition. After the heat treatment, the particle size is adjusted by an appropriate method, for example, mechanical crushing using a mortar or the like and sieving to obtain a porous material.

[0008]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but it goes without saying that the present invention is not limited to the following Examples.

EXAMPLE After dissolving 0.1 mol of aluminum chloride in 300 ml of distilled water, 41.4 g of 25 wt% aqueous ammonia was added to precipitate aluminum hydroxide. Thereafter, the mixture was aged in a warm water bath at 90 ° C. for 3 hours for aging to gel the aluminum hydroxide. The gel was kept in a thermostat at 100 ° C. for 24 hours, dried and then heat-treated at 300 ° C. for 4 hours in an electric furnace to obtain a sample. The reason for setting the heat treatment temperature to 300 ° C. is that ammonium chloride as a by-product
This is because sublimation occurs at a temperature of ° C., so long as the temperature is such that aluminum hydroxide is dehydrated to be porous and ammonium chloride as a by-product does not disappear by sublimation. This sample was crushed in an alumina mortar, and a sample passed through a 70-mesh sieve was used as a measurement sample for the following measurement.

The obtained sample was identified by powder X-ray diffraction measurement. The pore distribution was measured using a nitrogen adsorption method.
The absorption and desorption characteristics are measured using an automatic adsorption equilibrium measurement device.
The temperature in the measurement system was kept constant (25 ° C.), and the measurement was performed by a method (gravimetric method) in which the amount of adsorption was determined from the change in the sample weight when the water vapor pressure was changed to reach an equilibrium state. The amount of water vapor adsorption indicates the ratio of the weight of adsorbed water to the weight of a sample in a completely dry state. FIG. 1 shows a powder X-ray diffraction pattern of the sample obtained in the example. The diffraction pattern shows that the sample is γ-AlOOH
And ammonium chloride.
FIG. 2 shows the pore distribution of the sample obtained in the example.
The pore distribution of the obtained sample shows a peak top at a pore radius of about 2 nm. FIG. 3 shows the absorption / desorption characteristics (adsorption isotherm) of the sample obtained in the example. The adsorption isotherm of the obtained sample rapidly rises at about 80% relative humidity,
It can be seen from the desorption isotherm that most of the adsorbed water vapor was released at a relative humidity of about 60%.

Comparative Example FIG. 4 shows the absorption / desorption characteristics (adsorption isotherm) of calcium oxide and silica gel which have been conventionally used as a desiccant. Calcium oxide changes to calcium hydroxide after absorbing water, and is difficult to reuse by drying. Further, 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, both are unsuitable for dew condensation prevention applications which are used repeatedly.

[0012]

As described above, according to the method of the present invention,
A humidity control material comprising a composite of a porous metal hydroxide and a hygroscopic substance useful as a dew condensation preventing material can be produced relatively easily and at low cost. Such a composite material has excellent moisture adsorption / desorption performance as described above, so that an extremely good dew condensation preventing function and its repeated use are possible, and also has a humidity adjusting function. It is not limited to use as an anti-condensation agent, but is also suitable as a humidity control material.

[Brief description of the drawings]

FIG. 1 is a graph showing a powder X-ray diffraction pattern of a material prepared in an example of the present invention.

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

FIG. 3 is a graph showing water vapor adsorption / desorption isotherms of materials prepared in Examples 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.

Continued on the front page (72) Inventor Masaya Suzuki 4-8-212, Matsuzaka-cho, Tajimi-shi, Gifu (72) Inventor Fumihiko Ohashi 169-2, Hirade-cho, Nishi-ku, Nagoya-shi, Aichi 2 Sandel 3C (72) Inventor Keiichi Inukai Aichi 1-605, Nishifushiya, Nakagawa-ku, Nagoya-shi, Japan (72) Inventor Shinji Watari 1-7-12 Minamigaoka, Chigusa-ku, Nagoya-shi, Aichi (72) Inventor Yasuo Shibasaki 2-Taobao, Atsuta-ku, Nagoya-shi, Aichi 4 (72) Inventor Kyoko Fukushima 115 Tenjin Shin, Kurobe City, Toyama Prefecture (72) Inventor Kazuo Aikawa 526-2 Kamikoizumi, Namerikawa City, Toyama F Term (Reference) 2E001 DB03 GA03 JA00 JB00 4D052 AA08 GA03 GA04 GB03 GB11 GB12 GB13 GB14 GB16 GB17 GB18 HA00 4G066 AA20B AA32A AA32B AA52D BA22 BA23 BA31 BA36 BA42 CA43 DA03 FA05 FA14 FA21 GA06 GA31

Claims (2)

[Claims] 1. A metal hydroxide is precipitated by adjusting the hydrogen ion concentration of an aqueous metal chloride solution with an aqueous ammonia solution, and the hydroxide gel obtained by stirring in a warm water bath is converted into a hygroscopic gel. A method for producing a humidity control material, comprising producing a composite of a porous metal hydroxide and hygroscopic ammonium chloride by heat-treating a by-product at a temperature that does not cause thermal decomposition. 2. A composite of a porous metal hydroxide having mesopore pores having a pore radius of less than 10 nm and a hygroscopic substance, and having a relative humidity of 80% or more and a water vapor of 60% or more of its own weight under a high humidity condition of 80% or more. Reusable moisture control material that can absorb water and easily release most of the adsorbed water vapor under normal humidity conditions of about 60% or less relative humidity.