JP2003096652A - Moisture absorbing and releasing sound absorbing material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a moisture absorbing and releasing sound absorbing material having lightness, sound absorbing property together with moisture controlling property. SOLUTION: This moisture absorbing and releasing sound absorbing material is obtained by impregnating a slurry comprising fly ash having SiO2 /Na2 O (weight ratio) of 5-20 and sodium hydroxide into a nonwoven fabric mat and then heat curing, and the material has 0.4-0.7 g/cm<3> of bulk density and >=5 wt.% of moisture absorbing and releasing rate. A part of the fly ash material is optionally replaced with silica fume.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a moisture absorbing / releasing sound absorbing material mainly composed of fly ash.

[0002]

2. Description of the Related Art In recent years, as the airtightness of buildings has increased, dew condensation has occurred, and the formation of mold and mites due to this dew condensation has become a problem. As a countermeasure, it is being sought to introduce a forced air-conditioning method using mechanical equipment and to make the building material itself have a moisture absorbing / releasing function to control the indoor humidity by a more passive method.

As a place to install such a moisture absorptive and desorptive material, in addition to the opening, it is less likely to be concealed by the installation of furniture, electric equipment, etc., and a ceiling portion where a flat surface having a relatively large area can be obtained is suitable. Conceivable. However, as a ceiling material, there are cases where the function of lightness and sound absorption is required, and a material satisfying these functions is not known at present.

On the other hand, various sound absorbing materials using fly ash have been developed, for example, Japanese Utility Model Publication No. 6-308.
Japanese Unexamined Patent Publication No. 20 discloses a sound absorbing material in which fine aggregate of coal ash is granulated into a desired diameter is bonded with an inorganic binder and is sintered and molded as a plate having continuous voids inside.
Further, Japanese Patent Laid-Open No. 6-118965 discloses a sound absorbing material obtained by heat-curing and molding inorganic particles with a resin such as isocyanate or polyol. However, although these sound absorbing materials have excellent sound absorbing properties, they are not lightweight,
In addition, the manufacturing method was complicated.

[0005]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a moisture absorbing / releasing sound absorbing material having light weight, sound absorbing property, and humidity control property.

[0006]

[Means for Solving the Problems] That is, according to the present invention, a non-woven mat is impregnated with SiO ₂ / Na ₂ O (weight ratio) of 5 to 5.
It is made by heating and curing a slurry consisting of 20 fly ash and sodium hydroxide, and has a bulk density of 0.4 to 0.7.
It is a moisture absorbing / absorbing sound absorbing material characterized by having a moisture absorbing / releasing rate of 5% by weight or more in g / cm ³ . The moisture absorbing and desorbing sound absorbing material of the present invention,
Part of the fly ash may be replaced with silica fume.

The present invention will be described in detail below. The fly ash used as the base material of the present invention is fine particles in exhaust gas collected by a dust collector provided in a flue of a coal-fired power plant. A SiO ₂ content of 40% or more is suitable for use. Silica fume is also referred to as silica flour, which is an ultrafine amorphous silica powder having an average particle size of 1 μm or less.

First, fly ash and an aqueous sodium hydroxide solution are mixed at a predetermined ratio to prepare a slurry composed of fly ash and an aqueous sodium hydroxide solution. On this occasion,
If you replace some of the fly ash with silica fume,
Since it has a high reactivity with sodium hydroxide, a moisture absorbing / desorbing sound absorbing material having excellent strength properties can be obtained, which is preferable. Next, a nonwoven fabric mat is impregnated with this slurry, and then heat-cured and molded (thermocompression molding) into a predetermined shape such as a plate shape to obtain the moisture absorptive and desorptive sound absorbing material of the present invention.

In the present invention, the weight ratio of sodium hydroxide (NaOH) to silica (SiO ₂ ) in fly ash (a mixture of fly ash and silica fume) is 5 to 20. If the amount of NaOH blended is less than 5, the amount of sodium aluminosilicate formed is small and the binder effect is reduced.
If the content of NaOH exceeds 20, excessively low-molecular-weight sodium aluminosilicate is produced, which precipitates in the form of glass and inhibits the porosity of the molded body. SiO ₂ / Na ₂ O (weight ratio)
Of 5 to 20 results in SiO _{2 in} fly ash
Is not completely reacted with NaOH, and most of it is left unreacted, and it is considered that a part of fly ash is converted to low molecular weight sodium aluminosilicate salt and efficiently binds unreacted fly ash. .

By hot pressing of the slurry, the siloxane skeleton of the silica in the fly ash undergoes the attack of sodium hydroxide and is cleaved into a low molecular weight product in the presence of water at the initial stage of heating, and the silanol group and the silanol group sodium salt are formed. To produce aluminosilicate sodium salt containing. Furthermore,
When heating progresses to a dehydrated state, a part of silanol groups that have been once generated is polymerized again to regenerate the siloxane structure, and the sodium aluminosilicate salt becomes a polymer. At this time, sodium aluminosilicate acts as a binder,
It is thought to combine unreacted fly ash.
The silanol groups in the sodium salt of aluminosilicate are mostly converted to a siloxane structure during the polymerization process, but some of them remain as they are, and the sodium salt of the silanol groups remains as they are to impart hydrophilicity to the molded article, which is excellent. It is considered to exhibit the moisture absorption and desorption characteristics.

In the present invention, it is important that the series of reactions described above is carried out via a non-woven mat. The reaction product of fly ash and sodium hydroxide is a kind of low-melting glass and usually forms a hard and brittle molded body. Due to the presence of the non-woven mat, the volume reduction rate in the dehydration process is reduced, and a stable porous structure can be obtained. Further, the non-woven fabric acts as an elastic reinforcing material and imparts flexibility to the molded body. Further, the presence of the non-woven fiber facilitates holding of the slurry, which brings about an advantage that handling property in manufacturing is improved.

As the non-woven mat used in the present invention, fibers such as polyethylene, polypropylene, polyester, nylon, vinylon and other fiber sheets, webs and pads are oriented in one direction or at random, and friction, entanglement and The fibers are bonded by adhesion, and those having a relatively low density and a large fiber gap and having a basis weight of about 200 to 500 g are suitable for use.

The nonwoven fabric mat used in the present invention is a thin layer mat-like nonwoven fabric having a basis weight of 200 to 500 g / m ² , impregnated with 6 to 24 times (in terms of solid content) of the slurry, and substantially 4 to 4. Excellent flexibility can be provided by using a molded product in which 15% of fibers are mixed. 4% fiber amount
If the amount is smaller, the reinforcing effect of the fiber cannot be sufficiently exerted, and the brittleness of sodium aluminosilicate cannot be solved. Also, 1
If it exceeds 5%, it is difficult to manufacture and the effect of fiber reinforcement is saturated, so that it does not make sense to increase the amount of fibers.

The moisture absorbing / releasing sound absorbing material of the present invention has a bulk density of 0.4.
It is required to be 0.7 g / cm ³ . Bulk density is 0.4g
If it is lower than / cm ³ , sufficient strength cannot be obtained, and 0.7g / cm ³
If it exceeds, the porosity is lost and the sound absorbing property deteriorates. This bulk density can be adjusted by changing the height of the stopper for the thickness control bar of thermocompression molding.

The moisture absorption / desorption rate of the moisture absorptive and desorptive material of the present invention is
It should be 5% by weight or more. If the moisture absorption / desorption rate is lower than 5% by weight, the dew-proofness is lowered. The moisture absorptive and desorptive rate in the present invention means that the moisture absorptive and desorptive material is placed in a thermo-hygrostat and 2
The conditions of 5 ° C.-RH 90% and 25 ° C.-RH 50% are repeated every 24 hours, and the weight A at the time when the moisture absorption weight and the moisture emission weight reach a substantially constant value is obtained. It is obtained by dividing by the dry weight B (% by weight).

Next, a method of manufacturing the moisture absorptive and desorptive sound absorbing material of the present invention will be described. First, an aqueous sodium hydroxide solution was added to fly ash or a mixture of fly ash and silica fume so that the SiO ₂ / Na ₂ O (weight ratio) was 5 to 20, and a ribbon mixer, a muller mixer, a kneader, a pug mill, etc. When these materials are put into the mixer of (1) and mixed by stirring at room temperature or under heating, a slurry is obtained.

Then, the nonwoven fabric mat is dipped in this slurry, and the excess slurry is squeezed out with a roller or the like.
A non-woven fabric mat impregnated with a predetermined amount of slurry is used. It is preferable to load this in a preliminary dryer and pre-dry it until the drying rate reaches about 20 to 40%. Finally, using a thermocompression molding device such as a hot press, for example, 100 to 200
The moisture absorptive and desorptive sound absorbing material of the present invention can be produced by thermocompression molding at a temperature of 5 to 30 minutes.

The moisture absorptive and desorptive sound absorbing material of the present invention has excellent sound absorbing properties and exhibits excellent water resistance without deliquescent during moisture absorption. Further, since it contains no organic matter, it has excellent fire resistance and incombustibility. Therefore, it is suitable not only as a ceiling material but also as a wall material for interior.

[0019]

Example 1 90 parts by weight of fly ash (manufactured by Chubu Electric Power Hekinan Thermal Power Station, SiO ₂ content 55% by weight) and silica fume (manufactured by Kinseimatic, EFACO silica fume, SiO ₂ content 9)
5 parts by weight) to 10 parts by weight, 85 parts by weight of 11.9% by weight sodium hydroxide aqueous solution are added and mixed by a universal mixer to obtain Si.
A slurry having O ₂ / Na ₂ O (weight ratio) of 9.0 was prepared. A non-woven mat cut to 50 × 50 cm (manufactured by Toa Boshoku Co., Ltd., polyolefin non-woven fabric N-12904B, basis weight 250 g / m ² ) was immersed in this slurry, and the excess slurry was squeezed with a roller to contain about 565 g of the slurry. A non-woven mat was prepared. 1 of this non-woven mat containing slurry
It was put in a hot air dryer at 60 ° C. and heated for about 40 minutes, and pre-dried until the water content became 25%. Next, this pre-dried non-woven fabric was used with 160 mm with a thickness control stopper of 7 mm.
It was placed in a hot press at 0 ° C. and thermoformed for about 10 minutes to obtain a formed plate having a thickness of 6.5 mm and a bulk density of 0.40 g / cm ³ . The molded plate thus obtained is cut into 50 × 200 mm,
A bending test was performed. The test conditions were centralized loading, span of 100 mm, and loading speed of 2 mm / min. The moisture absorption / desorption performance was measured as follows. The test piece cut out into 50 × 100 mm is placed in a thermo-hygrostat set to repeat the conditions of 25 ° C., 90% RH and 50% RH in a 24-hour cycle, and the water content of the test piece is changed for each humidity cycle. The moisture absorption rate and the moisture release rate were calculated from the measured values. In addition, the normal incidence sound absorption coefficient is based on JIS A 1405 "Method for measuring normal incidence sound absorption coefficient of building materials by in-pipe method" according to Bruel & Kj.
The measurement was performed using an aer 4206 type 2 microphone impedance measuring tube and a 3550 type multi-channel analysis system in a setting of a back air layer of 50 mm. The measurement results are shown in Tables 1 and 2.

Example 2 The thickness of 6.5 mm and the bulk density of 0 were obtained in the same manner as in Example 1 except that the content of the slurry (SiO ₂ / Na ₂ O was 9.0) in the nonwoven fabric mat was 1,391 g. A molded plate of 0.55 g / cm ³ was obtained. The same performance test as in Example 1 was performed on this molded plate.
The measurement results are shown in Tables 1 and 2.

Example 3 A thickness of 6.5 mm and a bulk density of 0 were obtained in the same manner as in Example 1 except that the content of the slurry (SiO ₂ / Na ₂ O was 9.0) in the nonwoven fabric mat was 1,799 g. A molded plate of 0.70 g / cm ³ was obtained. The same performance test as in Example 1 was performed on this molded plate.
The measurement results are shown in Tables 1 and 2.

Example 4 A fly ash of 100 parts by weight was used, silica fume was omitted, and SiO ₂ / Na ₂ O was changed to 8.4. A molded plate having a density of 0.40 g / cm ³ was obtained. The same performance test as in Example 1 was performed on this molded plate. The measurement results are shown in Tables 1 and 2.

Comparative Example 1 A thickness of 7.5 mm and a bulk density of 0.35 g / cm ³ were obtained in the same manner as in Example 1 except that the thickness of the stopper for thickness control was set to 7.8 mm and hot pressing was performed. A molded plate of was obtained. The same performance test as in Example 1 was performed on this molded plate.
The measurement results are shown in Tables 1 and 2.

Comparative Example 2 A thickness of 6.5 mm and a bulk density of 0.8 were obtained in the same manner as in Example 1 except that the slurry content of the non-woven mat was changed to 2,071 g.
A molded plate of 0 g / cm ³ was obtained. The same performance test as in Example 1 was performed on this molded plate. The measurement results are shown in Tables 1 and 2.

Comparative Example 3 The sodium hydroxide concentration was 4.95% by weight, and SiO ₂ / Na ₂ O was used.
A molded plate having a thickness of 6.5 mm and a bulk density of 0.40 g / cm ³ was obtained in the same manner as in Example 1 except that a slurry of 21.7 was prepared. The same performance test as in Example 1 was performed on this molded plate. The measurement results are shown in Tables 1 and 2.

[0026]

[Table 1]

[0027]

[Table 2]

[0028]

EFFECTS OF THE INVENTION The moisture absorbing / releasing sound absorbing material of the present invention is excellent in sound absorbing property and moisture absorbing / releasing property, is lightweight, and is also excellent in water resistance, fire resistance and economy, and is suitable as a ceiling material, as well as in construction. It is also useful as an interior material for automobiles. Further, the manufacturing method does not require special equipment and mainly uses fly ash, which leads to effective use of resources.

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) G10K 11/162 (72) Inventor Yasunori Fukushima 15-1 Shinko, Kisarazu City, Chiba Nippon Steel Chemical Co., Ltd. 72) Inventor Takuya Koga 7-21-11 Nishigotanda, Shinagawa-ku, Tokyo Inside Nippon Steel Chemical Co., Ltd. (72) Inventor Masanao Ohwaki 1043 Onigakubo, Tsukuba City, Ibaraki Kumagaya Gumi Technical Research Institute (72) ) Inventor Yoji Sugiki 1043 Onigokubo, Tsukuba, Ibaraki Prefecture Kumagai Gumi Technical Research Institute Co., Ltd. (72) Inventor Takeshi Sugiyama 1 Higashishinmachi, Higashi-ku, Nagoya-shi, Aichi Chubu Electric Power Co., Inc. In-house (72) Inventor Mori Impossible 1 F-20, Chubu Electric Power Co., Inc. Electric Power Technology Research Laboratories, 1-20, Kitakanyama, Otaka-cho, Midori-ku, Aichi Prefecture (Reference) 4L031 AB34 BA09 BA20 CA08 CA11 DA00 DA08 4L047 AA14 CB03 DA00 5D061 AA11 AA23 AA33 BB21

Claims (2)

[Claims] 1. A non-woven mat impregnated with SiO ₂ / Na ₂
It is made by heating and curing a slurry consisting of fly ash having an O (weight ratio) of 5 to 20 and sodium hydroxide, a bulk density of 0.4 to 0.7 g / cm ³ , and a moisture absorption and desorption rate of 5% by weight or more. A sound absorbing and absorbing material which is characterized by being 2. The moisture absorbing / absorbing sound absorbing material according to claim 1, wherein a part of the fly ash is replaced with silica fume.