JP2001072458A - Formaldehyde-absorbing wall material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject wall material raised in formaldehyde absorbency and maintaining its hardness and mechanical strength as well through obviating its cracking due to drying by mixing slaked lime and/or dolomite plaster with sepiolite powder in specific proportions. SOLUTION: This wall material is obtained by mixing slaked lime and/or dolomite plaster with sepiolite powder at 10-15 wt.%. Sepiolite, in terms of structure, has internal tunnels running along the full length, the tunnels forming a netty communicating porous structure, formaldehyde can be adsorbed easily therein. Therefore, as the compounding ratio of sepiolite becomes higher, formaldehyde absorbency of this wall material also gets greater; however, too high compounding ratio of sepiolite contributes to decrarasing the hardness of this wall material and increasing its shrinkage; also, sepiolite contains silica, being rich in thixotropy owing its network structure, therefore contributing to higher sag preventive effect and improved coatability of this will material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wall material having a high absorbing ability mainly for formaldehyde and the like.

[0002]

2. Description of the Related Art In recent years, as highly airtight and highly insulated houses have become widespread, air has been polluted by volatile organic chemicals generated from house building materials, equipment, and the like, and the resulting health problems have become a serious problem. I have. Formaldehyde is a representative of these volatile organic chemicals, is a colorless gas at room temperature, has a pungent odor, and its source is plywood,
Adhesives such as particle board, and adhesives for wallpaper, urea-formaldehyde-based substances often used as preservatives,
And it is said that heating equipment and smoking. When inhaled, it mainly irritates the eyes, nose and throat, causing discomfort, lacrimation, sneezing, coughing, nausea, dyspnea, and carcinogenicity.

On the other hand, Spanish minerals having fine pores called sepiolite are known, and have been known as having excellent moisture absorption and thixotropic properties, such as under-floor humectants, sealant adhesives, bitumen emulsions and the like. It is used for However, there is still no example in which this is used as a wall material for absorbing formaldehyde.

[0004]

The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems of harmful chemicals such as formaldehyde and the like, and found that sepiolite is excellent in formaldehyde absorption. In order to bring out the absorption of sepiolite as much as possible, attention was paid to the combination of plaster and dolomite plaster with excellent ventilation. The present invention has been completed by devising a formaldehyde absorption function and maintaining the texture, strength and workability of the plaster and dolomite plaster.

[0005]

SUMMARY OF THE INVENTION The main object of the present invention is to provide:
Formaldehyde is a representative chemical that harms health,
This is to utilize a substance that can process this formaldehyde, and we focused on sepiolite as that substance. The sepiolite is a sediment product formed by a chemical change in the precipitation of lakes and marshes under a dry climate in the new millennium, and is chemically a hydrous magnesium silicate. Its chemical structural formula is Si ₁₂ Mg ₈ O
_{30 (OH) 4 (OH 2} ) is displayed in 4 · _8H 2 O,
Regular tetrahedral silica is composed of two layers and an octahedral magnesium layer between them, and the center is combined with the silica layer with oxygen,
The magnesium is a discontinuous layer whose structure forms fine fibers. And structurally, it forms a porosity,
In addition, active points due to silanol groups (Si-OH) exist on the surface. From this, it can be expected that sepiolite has absorptivity and catalytic property for formaldehyde.

In order to apply the above-mentioned sepiolite to a wall material without losing its characteristics, the wall material after mixing the sepiolite does not block the porosity of the sepiolite.
In addition, it must be capable of introducing formaldehyde into the interior, and therefore, attention has been paid to a combination of plaster and dolomite plaster that are rich in air permeability (air intake). Because plaster burns and digests limestone to form slaked lime, and when kneading it with water, it reacts with carbon dioxide in the air and hardens in the process of being converted into calcium carbonate. Dolomite plaster fires dolomite,
Digest to calcium hydroxide and magnesium hydroxide,
Similarly, it is hardened in the process of forming calcium carbonate and magnesium carbonate, and therefore, has excellent air permeability in the process of reacting with carbon dioxide in the air.

Therefore, the following absorption test was carried out in order to examine how formaldehyde is absorbed by the combination of sepiolite and stucco.

[Formaldehyde absorption test] About 41 L
Each of the following test specimens (12.5 × 10 × 1.2 cm) was set up at a substantially central position in a closed constant temperature chamber, and about 0.1 ml of formaldehyde was injected into the constant temperature chamber and the room was stirred with a fan. After 30 minutes, the change in formaldehyde concentration in the room was measured. The results are as shown in Table 1.

[Table 1] As a result, diatomaceous earth, kanuma soil, zeolite and the like hardly showed a significant difference from the case of 100% by weight of slaked lime, whereas a mixture of 10% by weight of sepiolite showed a high absorption effect of formaldehyde.

Next, the mixing ratio of the sepiolite was changed, and the change in the formaldehyde absorption rate was observed.

[Table 2] As a result, the absorptance increased from around 10% by weight.
It was found that the absorption rate became maximum around 0 wt% (see FIG. 1).

[0010] This high absorption effect on formaldehyde was observed, in part, because sepiolite structurally has internal tunnels running along its entire length, which tunnels open to the surface. Therefore, it is considered that pores having different shapes and diameters form a porous structure connected in a network, and formaldehyde is easily adsorbed in these pores.
Also, many silanol groups (Si-OH) along the particle length
These are lined up at the edge part at 5mm intervals,
In the structure, a part centered on a water molecule coordinated with Mg (coordination water) forms an active site, which in part promotes the adsorption of formaldehyde and further oxidizes formaldehyde to formic acid. The effect of neutralizing with plaster and dolomite plaster alkali can be expected. In addition, the high formaldehyde absorption effect confirms that the plaster is excellent and secures a ventilation path without blocking the pores of sepiolite in the path.

Next, in the combination of the above-mentioned sepiolite and plaster and dolomite plaster, while maximizing the absorption and catalytic activity of sepiolite as much as possible, the plaster and dolomite plaster as the wall material are high. The texture, strength and workability must be maintained. Therefore, first, slaked lime as a main component of the plaster and sepiolite were mixed, and the following hardness test and shrinkage test were performed.

[Hardness test] A mixture of slaked lime and sepiolite was used as a base material, and an optimum amount of vine and glue were added as plaster to the base material, an appropriate amount of water was added, and the plaster was applied to the surface of the gypsum board with a trowel. When the mizuhiki was watched, the iron was pressed down, polished and air-dried to obtain a test specimen. In addition, the amount of mixed water was not constant because it varied depending on each sample, and the kneading hardness was unified, and the kneading hardness was the same as the degree of application to the plate for each sample. After the sample was lightly dried with a dryer in order to obtain uniformity, the surface hardness of the sample left for one week was measured. As a measuring method, a Mohs hardness meter and a pencil hardness meter were used. Mohs hardness: Stand the needle upright on the surface, shift it sideways without changing the angle, and read the scale where no damage was found. Pencil hardness: A pencil is set up at 45 degrees on the entire surface, shifted before the near side, and a pencil having a hardness not damaged by the pencil core is taken as hardness.

The results are as shown in the table below.

[Table 3] As a result, the hardness tends to decrease as the mixing ratio of sepiolite increases.
%, The Mohs hardness is maintained at 0.15 or more and the pencil hardness is maintained at 3H or more, and the wall hardness can be practically used (see FIG. 2).

[Shrinkage Test] A specimen was prepared in the same manner as in the hardness test, and the change in drying shrinkage was measured. Table 4 shows the results.

[Table 4]

As a result, it was found that as the mixing ratio of sepiolite increases, the hardness decreases and the shrinkage ratio also increases (see FIGS. 2 and 3). If it exceeds 20 wt%, cracks occur. The shrinkage ratio was 3 times or more as compared with that of 100% by weight slaked lime. Sepiolite as a wall material had a large drying shrinkage and a low hardness.

According to the above tests, the absorption rate of formaldehyde is desirably 10 wt% or more, which increases the absorption rate.
It is necessary to set the content to not more than wt%. Therefore, the wall material of the present invention is excellent in formaldehyde absorption rate by setting the sepiolite powder in the range of 10 to 15 wt% with respect to slaked lime and / or dolomite plaster, and has no cracks due to drying and has high hardness. It has been proved that the hardness as hard as possible can be maintained and the strength as a wall material can be sufficiently secured.

At the same time, sepiolite contains silica and is rich in thixotropy due to its network structure, and as a wall material, has excellent anti-sagging effects and can exhibit properties of improving coating properties.

The dolomite plaster can be treated in substantially the same manner as the plaster, and can be treated in the same manner as the plaster. In the present invention, formaldehyde is mainly considered as a target harmful substance to be absorbed. However, when other harmful chemical components are present, the absorption thereof is not denied.

[0019]

[Example 1] Sepiolite 15k for 90 kg slaked lime
g was mixed with 1 kg of square glue and 0.4 kg of methylcellulose as a glue component, 1 kg of vine was further mixed, an appropriate amount of water was added, and the mixture was applied to a wall with a trowel. As a result, the absorption of formaldehyde was about 62.8 wt%, there was no crack, and the hardness was 0.3 on the Mohs hardness tester. It has a high formaldehyde absorption rate, a beautiful plaster texture without cracks on the surface, and has a hardness that prevents scratches.

[0020]

[Example 2] 90 kg of dolomite plaster was used, and 15 kg of sepiolite was added.
g, 0.4 kg of methylcellulose and 1k
g, mixed with an appropriate amount of water, applied to the wall with a trowel, pressed down, polished and air-dried. as a result,
The absorption of formaldehyde was about 61.5 wt%, there was no crack, and the hardness was 0.3 on the Mohs hardness scale. It has a high formaldehyde absorption rate and a clean dolomite plaster texture with no cracks on the surface, and has a hardness that prevents scratches.

[0021]

COMPARATIVE EXAMPLE 90 kg of Portland cement was mixed with 15 kg of sepiolite, an appropriate amount of water was added, and the mixture was applied to a wall with a trowel and air-dried. As a result, although there is no crack on the wall, the formaldehyde absorption rate is about 5 wt%.
And the absorption rate of formaldehyde was extremely low.

[0022]

According to the present invention based on the above configuration and operation,
The combination of sepiolite and stucco can effectively absorb formaldehyde as a harmful substance generated from new building materials and the like, and has an excellent effect of minimizing adverse effects on human health. Also, at the same time,
The present invention is highly effective in that it can maintain high texture as a plaster without cracking even when dried, and can have strength and workability as a wall material.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between the mixing ratio of sepiolite and the absorption of formaldehyde.

FIG. 2 is a graph showing the relationship between the samples of Table 3 and Mohs hardness.

FIG. 3 is a graph showing the relationship between the samples in Table 4 and the volume shrinkage.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Yasuhiro Tamura 4201 Kuzuu, Kuzuu-cho, Anso-gun, Tochigi Prefecture F-term in Komagata Lime Industry Co., Ltd. 4C080 AA05 BB02 BB04 CC02 CC12 HH05 JJ03 KK08 LL10 MM01 NN02 QQ03 4G012 PA06 PA21 PB40 4G066 AA17B AA43B AA63B AC02C BA35 BA36 CA52 DA03 FA25 FA37

Claims (2)

[Claims] 1. A wall material comprising sepiolite powder mixed with slaked lime and / or dolomite plaster at a ratio of 10 to 15 wt% to absorb harmful components such as formaldehyde. 2. The wall material according to claim 1, wherein the sepiolite component is 15 wt%.