JP2972883B1 - Hygroscopic porous structure and method for producing the same - Google Patents

Abstract

An object of the present invention is to provide a method for producing a porous wall material exhibiting an autonomous humidity control function by forming and solidifying a porous powder having no formability without reducing the amount of water vapor adsorbed. SOLUTION: A porous wall material having pores on the order of nanometers having both hygroscopicity and water absorbability without impairing the porosity by forming and drying a molded / solidified body utilizing the viscosity of silica sol. To manufacture. [Effect] Capillary condensation phenomenon that occurs in pores on the order of nanometers by providing an energy-saving method for producing a porous solid body that is a molding method that balances the strength of a non-moldable porous powder with the amount of water vapor adsorbed. Thereby, it is possible to supply a functional material having a humidity adjusting function autonomously without giving external energy.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a porous structure exhibiting an autonomous humidity control function by molding and solidifying without reducing the amount of water vapor adsorbed on a non-moldable porous powder. Etc., and more specifically,
The present invention prevents condensation, such as tiles for interior wall materials, etc., to ensure a comfortable space by properly adjusting the indoor humidity,
The present invention relates to an interior wall material having an excellent autonomous humidity control function and a method for producing the same.

[0002]

2. Description of the Related Art In recent years, the living environment has been increasing comfort with the improvement of heat insulation and the enhancement of heating equipment. Internal condensation occurs, and rot bacteria and the like multiply and deteriorate the strength of the wall material. As a result, it may not be possible to maintain sufficient strength against the earthquake. In addition, allergic problems associated with the propagation of mites and molds have also occurred. Furthermore, since energy consumption is involved, the impact on the global environment in addition to cost is not negligible.

The above-described artificial environmental control using a heat insulating material, a heater, or the like attempts to control the temperature in order to comfortably enjoy Japanese environmental conditions that cause high-temperature, high-humidity or low-temperature dew condensation. It is considered that a comfortable environment can be realized by controlling the humidity only.

[0004] For this reason, the humidity control function is provided to the building material itself so that the humidity in the room can be adjusted without the need for air conditioning equipment or electric power, and the dehumidification and mold resistance can be obtained. Construction materials are being developed. Conventionally, calcium silicate building materials (Japanese Unexamined Patent Publication No. Hei 5-29367) have been used as humidity control building materials.
Diatomaceous earth-based building materials (JP-A-4-354514), zeolite-based building materials (JP-A-3-93662), and silica gel-based building materials (JP-A-7-284658) have been developed. Also, after heat treatment of kaolin mineral,
A method for producing a porous interior wall material having an autonomous humidity control function by eluting amorphous silica (selective dissolution method) has been developed (Japanese Patent Application No. 9-202522).

As described above, various humidity control building materials have already been developed, but they have the following problems. Conventional calcium silicate humidity control building materials have a moisture absorption capacity of 1
Since the content is 0% by weight or less, when the high humidity state continues for a long period of time such as during the rainy season, the amount of moisture absorption of the building material is quickly saturated, and the humidity control property and the dew-proof property are lost. Since a zeolite-based building material uses a cement-based binder, its moisture absorption / desorption property is reduced, and is not necessarily suitable for use as an efficient humidity-controlling building material. Diatomaceous earth humidity control building materials are difficult to save energy because they are fired and solidified at 800 to 1000 ° C. In addition, the method for producing a porous γ-alumina body by the selective melting method requires a process of further molding the prepared porous powder after heat treatment and firing at about 1000 ° C., which is disadvantageous in energy cost. Furthermore, silica gel, which has excellent moisture absorption, also has problems of cracking and strength when it becomes large due to poor moldability.
It was used only in granular form and could not be used as a wall material as a large molded body.

Some silica gels are exemplified to be formed into a molded body by using an organic binder (polyvinyl alcohol, starch, carboxymethyl cellulose, water-soluble acrylic resin) (Japanese Patent Application Laid-Open No. 7-28465).
No. 8). However, the organic binder has poor heat resistance and has the double drawback of blocking pores and inhibiting moisture absorption. In this embodiment, the equilibrium moisture absorption of silica gel alone is 50% by weight at 90% RH. However, after molding with an organic binder, even when left at 90% RH for 10 hours, the moisture absorption rate is reduced to 23% by weight.

[0007] In Japanese Patent Application Laid-Open No. 10-18445, the above polyvinyl alcohol, MMA resin,
Water-absorbing polymers such as polyacrylates, starch-acrylic acid graft copolymers, and vinyl acetate-acrylic acid ester copolymer ketone compounds cause not only a decrease in strength due to water absorption, but also a large dimensional change upon water absorption. Therefore, it is pointed out that it is difficult to form a wall material using these materials. Further, Japanese Patent Application Laid-Open No. 10-18445
In the publication, a polyolefin-based resin is used as a binder, but the examples shown in Table 1 have a maximum moisture absorption of only 7% or less.

[0008]

Under such circumstances, the present inventors, in view of the above-mentioned prior art, have proposed a porous structure useful as a functional building material having an autonomous humidity control function in an energy-saving manner. As a result of intensive research with the aim of developing a body, colloidal silica sol is added to porous powder that does not have moldability, and it is molded, dried, and solidified so as not to reduce the moisture absorption and desorption characteristics of water vapor As a result, it has been found that the intended purpose can be achieved, and the present invention has been completed. An object of the present invention is to provide a “breathing wall material” molded body having a large amount of moisture absorption and strength in order to fundamentally solve the above-mentioned problems, and its gist is an inorganic porous material having poor moldability. By adding silica sol of ultra-fine particles of the order of several nanometers to the porous powder as a nonflammable binder, and adding a fibrous substance to prevent cracking and shrinkage, it does not reduce the moisture absorption and also increases the strength. The purpose of the present invention is to form a moisture-absorbing and releasing porous wall material having excellent nanometer-order pores.

[0009]

The present invention for solving the above-mentioned problems comprises the following technical means. (1) A method for producing a moisture-absorbing and desorbing porous structure having an autonomous humidity control function, wherein a mesoscopic size (2 to 50 nm) is used so as not to reduce the moisture-absorbing and desorbing characteristics of water vapor.
A method for producing an energy-saving moisture-absorbing and desorbing porous structure, characterized in that a porous material is solidified by mixing a silica sol with a porous powder having the above-mentioned pores and then drying, followed by sintering. (2) The moisture absorbing and releasing porous structure according to (1), wherein a fibrous substance is mixed with the composition in order to prevent cracks and surface irregularities due to shrinkage of the solidified body during drying. Manufacturing method. (3) Mesoscopic size of porous powder (2 to 50)
at least one selected from the group consisting of silica gel, mesoporous silica, M41S, FSM16, pillared clay, selective dissolution method kaolinite, porous glass powder, allophane, diatomaceous earth, and aluminum hydroxide dehydrate having pores of (nm) The method for producing a moisture-absorbing and releasing porous structure according to the above (1), which is characterized in that: (4) The method for producing a moisture-absorbing and releasing porous structure according to the above (1), wherein the silica sol comprises fine particles having a particle size of 20 nm or less. (5) The method for producing a moisture-absorbing / desorbing porous structure according to the above (1), wherein the silica sol is held in a dry weight of 20 to 50 parts by weight with respect to 100 parts by weight of the porous powder. (6) A moisture-absorbing and releasing porous structure having an autonomous humidity control function obtained by the method according to any one of the above (1) to (5). (7) A humidity control material comprising a moisture-absorbing and releasing porous structure having an autonomous humidity control function according to (6). (8) The humidity control material according to (7), which is a humidity control building material, a wall material, an inner wall material, a ceiling material, a desiccant, or a member for configuring a space having a humidity control function.

[0010]

Next, the present invention will be described in more detail. As described above, the present invention provides a porous structure having nanometer-order pores having both hygroscopicity and water absorbency without impairing porosity by forming and solidifying a body utilizing the viscosity of silica sol. It is characterized by producing the body. Examples of the porous material having mesoscopic pores (2 to 50 nm) used as a raw material in the method of the present invention include:
For example, B-type silica gel specified in JIS Z0701,
Alternatively, silica gel for liquid chromatography may be used. Alternatively, kaolinite, porous glass powder, diatomaceous earth, aluminum hydroxide dehydrate, allophane, or the like may be used. Furthermore, M which is not amorphous but has a structure
Mesoporous silica such as CM41, M41S, FSM16 and the like are exemplified as having excellent water vapor absorption / release properties. These raw materials are crushed by an appropriate means, for example, 3
After being adjusted to 0 mesh or less, more preferably 70 mesh or less, a silica sol such as colloidal silica, fumed silica, snowtex, Ludox,
After adding cataloid S or the like until fluidity is obtained and pouring into a mold, for example, the porous material is solidified by drying at room temperature to 100 ° C. for 3 to 24 hours, and the porous structure is formed without sintering. obtain.

In the present invention, any one or more selected from the above porous powders can be used. The silica sol is preferably composed of fine particles having a particle size of 20 nm or less. As a result, an effect is obtained in which the sol particles enter between large particles of several microns and the adhesive consolidation effect increases. Further, it is preferable that the silica sol is mixed in a dry weight of 20 to 50 parts by weight with respect to 100 parts by weight of the porous powder. In this case, if the amount of the silica sol is less than 20 parts by weight, the consolidation property is reduced and a brittle state is caused, which is not preferable.
If the amount is more than the weight part, the porous powder and the silica sol are easily separated up and down during defoaming, which is not preferable. The shape and structure of the above-mentioned structure, its forming method, drying method and conditions are not particularly limited, but preferably, it is a plate-shaped / solid shape and structure, and a ceramic slurry casting method. And drying at room temperature to 100 ° C. for 3 to 24 hours. The present invention is characterized in that it only needs to solidify the porous material and does not sinter. As a result, advantages such as energy saving, no firing shrinkage, few steps, and no need for expensive equipment such as a firing furnace are obtained. The porous structure is useful as, for example, a wall material, a closet, a desiccant for a large area of a closet / storage, a humidity control material laid on the top or bottom of an art display case, and the like.

As one embodiment of the method of the present invention, in order to prevent cracks and surface irregularities due to shrinkage during drying of the solidified product, after adding fibers such as pulp or glass fiber of an appropriate length, stirring is performed. By vacuum defoaming, pouring into a mold and drying, cracking and shrinkage can be prevented and the strength can be increased as compared with the above method. In this case, the type and form of the fibrous material are not particularly limited, but preferably, short fiber pulp, long fiber pulp, glass wool, carbon fiber, polymer fibers such as vinyl, and mineral fibers such as sepiolite are exemplified. You. By the above method, a porous structure having pores on the order of nanometers exhibiting an excellent autonomous humidity control function can be manufactured.

The main characteristics of the porous structure manufactured by the above method are shown below. 1) It has a water absorption of 0.5 g or more per 1 g. 2) It has a hygroscopic property of 0.25 g or more per 1 g. 3) The dimensional change between drying and water absorption is 0.5% or less. 4) 14 kgf / c per square millimeter of molded article
It has a compressive strength of at least m ² .

In the present invention, it is important to employ a molding method that balances the strength of a non-moldable porous powder with the amount of water vapor adsorbed, and an energy-saving porous solid preparation method that does not include a sintering step. Accordingly, the present invention makes it possible to provide a functional material having a humidity adjusting function autonomously without giving energy from the outside, due to a capillary condensation phenomenon occurring in pores on the order of nanometers. I do.

[0015]

Next, the present invention will be specifically described based on examples, but the present invention is not limited to only the examples. Examples 1 to 7 Silica gel B was used as a raw material. After crushing this raw material in a pot mill, a powder under a 70 mesh sieve was prepared. Furthermore, the length is 40-100 mesh (0.15
-0.425 mm) short fiber pulp (Cellulose powder D, manufactured by Advantech Toyo) and 2
mm long fiber pulp (Advantech Toyo As
hless Pulp) and Glass wool
(Φ1 μm manufactured by Masuda Rika) were prepared. Silica sol includes Snowtex N-type (Nissan Chemical, particle size 10 ~
20 nm). The ratio of silica gel, silica sol and fiber is 26: 64.9: 9.1, 28.1: 70.
3: 1.5, 28.3: 70.3: 1.0 and 21.
Mix at a weight ratio of 9: 76.5: 1.6 and mix at room temperature and 40
It dried at 24 degreeC and 24 hours, and was set to Examples 1-7, respectively.
(Table 1)

The compressive strength (Table 1 and FIG. 1) was the weakest when mixed with short fiber pulp (Examples 1 and 2).
kgf / cm ² , the mixture of long fiber pulp (Examples 5 and 6) was slightly larger than about 20 kgf / cm ² , and the mixture of glass fibers (Examples 3, 4, and 7) was 25 kgf / cm ^2. cm ² , which was the largest value equivalent to that of diatom shale ceramics.

The water vapor adsorption isotherm of the sample was measured at 25 ° C. and a relative humidity of 10 to 9 using EAM-01 manufactured by JT Toshi.
It was measured in the range of 0% (FIG. 2). Short fiber pulp mixed and dried at room temperature and 40 ° C. (Examples 1 and 2)
Has a large decrease of about 30%, and has recovered to about 40% when dried at 100 ° C. The mixture containing long fiber pulp showed a small amount of warpage due to drying, and the maximum moisture absorption was as large as about 40% at room temperature and 40 ° C. drying (Examples 5 and 6), and about 50% at 100 ° C. drying. Glass fibers mixed and dried at room temperature and 40 ° C. (Examples 3, 4 and 7) had a maximum moisture absorption of about 45%.

The water absorption of Examples 1 to 7 after immersion in water for 24 hours is 50% or more, the density is about 0.8 g / cm ³ , and the dimensional change after immersion in water for 1 day is 0.1% or less. Was less than the measurement error.

Comparative Example 1 The compressive strength and water vapor adsorption isotherm of a commercially available calcium silicate-based humidity control material (Muselite manufactured by Asahi Glass Co., Ltd.) were examined. The maximum water vapor adsorption was about 7%. The compressive strength was 6.5 kgf / cm ² . From the above results, it can be said that the method of the present invention was able to prepare a solidified silica gel having a compressive strength of 5 to 7 times and a compressive strength of 2 to 3 times as large as the maximum water vapor adsorption of a commercially available calcium silicate-based humidity control wall material. . The characteristics of Examples 1 to 7 of the present invention and Comparative Example 1 are shown.

[0020]

[Table 1]

[0021]

As described above, the present invention provides an autonomous control without impairing the amount of adsorbed water vapor by adding colloidal silica sol to porous powder having no moldability, molding and drying. According to the present invention, it is possible to manufacture a tile or the like having a wet function, and according to the present invention, a porous structure having nanometer-order pores having both moisture absorption and water absorption without impairing the porosity. It can be manufactured, and a functional building material having an autonomous humidity control function can be produced in an energy-saving manner. Therefore, the present invention greatly contributes to the industry as a technology that contributes to realizing a comfortable living environment, saving energy, and providing environmentally friendly materials.

[Brief description of the drawings]

FIG. 1 shows the relationship between compressive strength and density in Examples 1 to 7 of the present invention and Comparative Example 1.

FIG. 2 shows water vapor adsorption isotherms of Examples 1 to 4 and Comparative Example 1 of the present invention.

FIG. 3 shows water vapor adsorption isotherms of Examples 5 to 7, raw material silica gel powder and Comparative Example 1 of the present invention.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Masaya Suzuki 4-8-212 Matsusaka-cho, Tajimi-shi, Gifu (72) Inventor Yasuo Shibazaki 2-4, Daiho, Atsuta-ku, Nagoya-shi, Aichi (56) References 8-26842 (JP, A) JP-A-5-29333 (JP, A) JP-A 8-299745 (JP, A) JP-A-63-217040 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) E04B 1/64 C04B 38/00 301

Claims (8)

(57) [Claims] 1. A method for producing a moisture-absorbing and desorbing porous structure having an autonomous humidity control function, wherein a mesoscopic size (2 to 5) is selected so as not to reduce the moisture-absorbing and desorbing characteristics of water vapor.
An energy-saving method for producing a moisture-absorbing and desorbing porous structure, comprising mixing a silica sol with a porous powder having fine pores having a pore size of 0 nm, followed by drying to solidify the porous material and not sintering. 2. The moisture-absorbing and releasing porous structure according to claim 1, wherein a fibrous substance is mixed with said composition in order to prevent cracks and surface irregularities due to shrinkage of said solidified body during drying. How to make the body. 3. The porous powder has silica gel having pores of mesoscopic size (2 to 50 nm), mesoporous silica, M41S, FSM16, pillared clay, selective dissolution method kaolinite, porous glass powder, allophane, diatomaceous earth, 2. The method for producing a moisture-absorbing and releasing porous structure according to claim 1, wherein the porous structure is at least one selected from dehydrated aluminum hydroxide. 4. The method for producing a moisture-absorbing and releasing porous structure according to claim 1, wherein the silica sol comprises fine particles having a particle size of 20 nm or less. 5. The method for producing a moisture-absorbing and desorbing porous structure according to claim 1, wherein the silica sol is held in a dry weight of 20 to 50 parts by weight with respect to 100 parts by weight of the porous powder. 6. A moisture-absorbing / desorbing porous structure having an autonomous humidity control function obtained by the method according to claim 1. Description: 7. A moisture-conditioning material comprising a moisture-absorbing and releasing porous structure having an autonomous humidity-controlling function according to claim 6. 8. The humidity control material according to claim 7, which is a humidity control building material, a wall material, an inner wall material, a ceiling material, a desiccant, or a member for forming a space having a humidity control function.