JP2009023864A - Functional building material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a functional building material which has excellent moisture absorbing and releasing characteristics, is excellent in adsorbability of VOC, malodorous components or the like and also has a function to make harmless these adsorbed materials, and has a performance preventing pollution of the air in the room over a long period of time and keeping comfortable environment. <P>SOLUTION: The functional building material is composed of calcium silicate hydrate having a structure with fine pores which can be obtained by aging an inorganic formed product that is obtained by forming a raw material containing diatomaceous earth of 30-75 mass% at a temperature of 150-200°C and under pressure of 470-1,560 kPa. Preferably in the functional building material, the calcium silicate hydrate having a structure with fine pores is one that has fine pores with a pore size of 2-200 nm and has a moisture content of 2-20 mass%, and that contains free weakly alkaline water other than the bound water of the calcium silicate inside the fine pores. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  Since the present invention has an excellent humidity control ability and has a function of adsorbing harmful gases such as volatile organic compounds and detoxifying harmful gases by alkali decomposition, it can be used for interior building materials of buildings. It is related with the functional building material used suitably.

  In Japan, which is hot and humid in summer, buildings have been traditionally used for buildings with consideration of ventilation and structural materials such as wood and earth walls. . However, in recent years, with the development of air-conditioning equipment, it has been required to improve the airtightness of buildings, and the development of new building materials that make it possible to progress, and various new building materials will be used. became. These new building materials have excellent airtightness, fire resistance, and sound insulation performance, and there are no problems such as condensation when using air conditioning equipment, but the humidity control function is insufficient and air conditioning is not used. Condensation on the surface of building materials is a problem.

  In addition, due to the increased confidentiality of buildings, VOCs (volatile organic compounds) generated from these new building materials, adhesives and paints used in furniture, and preservatives used in flooring Indoor contamination has become a bigger problem as a cause of sick house syndrome.

  For the former dew condensation problem, the applicant has proposed the humidity control building material of Patent Document 1 as an interior building material having excellent moisture absorption and desorption characteristics. Since the humidity control building material of this patent document 1 shows a high moisture absorption / release rate, moisture absorption / release capacity, and has excellent mechanical properties, if used as an interior building material, the living space can be maintained at a comfortable humidity. It becomes possible.

  On the other hand, even for the latter VOC problem, the humidity control building material of Patent Document 1 also has a function of adsorbing VOC and the like by the porous material contained in the base material. However, there is a limit in the amount of adsorption, and there has been a problem that when the saturated adsorption amount is reached after long-term use, the adsorbed VOC, malodorous components and the like are re-released.

Japanese Patent No. 3762851

  The present invention further improves the adsorption capacity of the moisture-control building material disclosed in the above-mentioned Patent Document 1 while maintaining its excellent moisture absorption and desorption characteristics, and also adsorbs these substances. It aims at providing the functional building material which added the function which makes harmless to this humidity-control building material.

As a result of diligent research to achieve the above object, the present inventors have conducted fine molding by curing the molded body under high temperature and high pressure in the manufacture of the humidity-controlled building material disclosed in Patent Document 1 described above. Calcium silicate hydrate with pore structure is formed, has excellent humidity control speed and humidity control capacity, detoxifies VOC and malodor components, and does not re-release VOC or malodor components The present inventors have found that building materials can be obtained and have completed the present invention.
That is, the present invention is a fine product obtained by curing an inorganic molded body obtained by molding a raw material containing 30 to 75% by mass of diatomaceous earth at a temperature of 150 to 200 ° C. and a pressure of 470 to 1560 kPa. A functional building material comprising calcium silicate hydrate having a structure having pores is provided.

  The functional building material of the present invention has excellent mechanical properties as an interior building material of a building, excellent humidity control function, as well as excellent adsorbability of VOC and malodorous components that cause sick house syndrome. And, because it has the function of dissolving and decomposing these adsorbed substances with weak alkaline water to make them harmless, it has the ability to prevent indoor air contamination over a long period of time and maintain a comfortable environment, Its application in the architectural field is wide.

Hereinafter, the functional building material of the present invention will be described based on its preferable manufacturing method.
Diatomaceous earth is a starting material for obtaining calcium silicate hydrate having fine pores in the functional building material of the present invention. Even if the diatomaceous earth content in the starting material is large or small, it becomes difficult to produce the desired calcium silicate hydrate, leading to a decrease in the strength of the functional building material. Therefore, excessive or excessive blending is avoided. In the present invention, for example, when the SiO ₂ content of diatomaceous earth is 78% by mass, the blending amount of diatomaceous earth is 30 to 75%, preferably 50 to 70% of the whole raw material by mass ratio. It is possible to obtain a functional building material having the characteristics that both weak alkali decomposition (detoxification) and strength are excellent.
The composition of diatomaceous earth varies slightly depending on the state of production and place of production. While having a large variation can be used by correcting the amount, SiO ₂ content is preferred to use more than 70% of diatomaceous earth. If diatomaceous earth having a SiO ₂ content of less than 70% is used, it does not react sufficiently due to the influence of impurities, and the intended pores may not be obtained.
Examples of the raw material component of the inorganic molded body other than diatomaceous earth include slaked lime, quartz sand, gypsum, pearlite, and grinding dust, and may include pulp, fibers (inorganic and organic), etc. in addition to these inorganic materials.

The inorganic molded body used in the present invention is most suitably molded by papermaking, but there is no difference in performance regardless of which method is used as long as it is a method for producing a plate-shaped building material such as press molding. As an example, when molding by papermaking, the raw material of the inorganic molded body is 30 to 75% by mass of diatomaceous earth, 20 to 40% by mass of slaked lime, 1 to 10% by mass of gypsum sand, 1 to 10% by mass of gypsum, and 1 to 10% by mass of pulp. It is preferable to use a raw material containing 0.1 to 3% by mass of fibers.
In order to enable molding in papermaking, it is required that the slurry before papermaking has a certain degree of viscosity, but viscosity can be imparted by blending gypsum into the raw material. When gypsum is blended, the amount of gypsum is preferably 1 to 10%, more preferably 3 to 7% of the entire raw material in mass ratio. If the amount of gypsum is less than 1%, papermaking becomes difficult. Moreover, when papermaking becomes difficult, the addition of diatomaceous earth for imparting sufficient humidity control ability becomes impossible. On the other hand, if the amount of gypsum is more than 10%, explosion may occur due to expansion, which is not preferable.
Regardless of natural products and synthetic products, any of two water, half water, and anhydride can be used for the gypsum.

In the present invention, when slaked lime is blended as a raw material, the slaked lime forms calcium silicate in the form of tobermorite (5CaO · 6SiO ₂ · nH ₂ O) using a part of quartz sand and diatomaceous earth as a Si source in the curing process after molding. To do.
The CaO / SiO ₂ molar ratio forming tobermorite should theoretically need to be set to a value close to 0.83, but since the solubility of SiO ₂ is lower than that of CaO, SiO It is preferable to set the amount to be excessive.
When mix | blending slaked lime with a raw material, the compounding quantity of slaked lime is 20 to 40% of the whole raw material by mass ratio, More preferably, you may be 25 to 35%. If the amount of slaked lime is too large, the residual amount of diatomaceous earth necessary to obtain fine pores in the molded body is reduced, and sufficient humidity control and weak alkali decomposition (detoxification) of VOC cannot be obtained. When there is too little quantity of slaked lime, the amount of calcium silicate production will decrease and what has sufficient intensity as a building material may not be obtained.

  In this invention, silica sand can be mix | blended with a raw material as one of the Si sources of a calcium silicate. Since silica sand has a slow reaction rate with Ca, it is preferable to mix it with the raw material because it regulates the reaction rate between diatomaceous earth and Ca source, which has a high reaction rate, and facilitates crystallization. When silica sand is blended with the raw material, the blending amount of the silica sand is preferably 1 to 10%, more preferably 1 to 5% of the entire raw material by mass ratio.

In addition to the inorganic material, pulp and fibers may be blended in the raw material of the inorganic molded body used in the present invention. Pulp and fiber play a major role in improving the strength and toughness of the molded body. As the fiber, fibrous inorganic materials such as sepiolite and wollastonite, and organic fibers such as rayon, nylon, polypropylene, polyester and vinylon can be used, and those having a length of 3 to 12 mm and a thickness of 10 to 150 μm are used. It is preferable to do this. If the length and thickness are not appropriate, the characteristics of the fiber will not be sufficiently developed, or specific damaging will be caused by the addition of the fiber, conversely, the strength and thermal characteristics will be reduced, and the appearance will be poor. Become.
When the fiber is blended with the raw material, the blending amount of the fiber is preferably 0.1 to 3%, more preferably 0.5 to 2.0% of the entire raw material by mass ratio. This is because if the blending amount of the fiber is small, the effect of adding strength cannot be sufficiently exerted, and if it is too large, a dull is formed due to a decrease in dispersibility, leading to a decrease in strength.

Various kinds of pulp such as wood pulp, bamboo pulp, boro pulp and linter pulp can be used as the pulp, but wood pulp occupying 90% of the production amount is preferable. Further, it is not necessary to use virgin pulp, and recovered pulp produced from waste paper can be used without any problems in terms of characteristics, and is the most preferable material in consideration of cost. Further, the pulp can be beaten and used.
The fiber length of the pulp is 0.3 to 6 mm, preferably 0.5 to 4 mm, so that it has not only excellent mixing with inorganic materials but also toughness and other characteristics. It is possible to obtain a building material board that is excellent in the above.
When the pulp is blended with the raw material, the blending amount of the pulp is preferably 1 to 10%, more preferably 2 to 5% of the entire raw material by mass ratio. This is because if the added amount of the pulp is small, the effect of adding strength is not sufficiently exerted, and if it is too much, a dull is formed due to a decrease in dispersibility, leading to a decrease in strength.

  Moreover, pearlite can also be mix | blended with the raw material of the inorganic molded object used by this invention. The use of pearlite having a particle size of 0.6 mm or less is preferred from the standpoint of mixing properties and strength. In addition, the blending amount in the raw material can be further reduced by increasing the blending amount, but excessive blending leads to a decrease in strength. It is preferable to set it to -5%.

  The functional building material of the present invention is made into a product by adjusting the thickness of the molded body by grinding with a sanding machine at the final stage of production, but the fine powder (grinding dust) generated at that time is reused as a raw material. be able to. The blending of the grinding dust is effective for reducing the cost, but excessive blending leads to a decrease in strength, so the blending amount is preferably 10% or less, particularly 2 to 7% of the whole raw material by mass ratio.

A general method for producing an inorganic molded body used in the present invention is as follows. First, a predetermined amount of the above diatomaceous earth, silica sand, slaked lime, gypsum, fiber and pulp is blended, and further, grinding dust and pearlite are added as necessary. Is stirred and mixed with water to prepare a slurry. When molding by papermaking, it is preferable to adjust a slurry having a concentration of 2 to 5%. When other molding methods are used, the slurry concentration is adjusted to be suitable for the production method.
The molding is preferably paper making of the slurry, but various methods for producing various plate-shaped building materials can be used. Paper making may be performed by a normal method. The green board after papermaking is subjected to a molding process such as pressing, and then cut to obtain an inorganic molded body that is 1 to 2 mm thicker than a predetermined thickness of the functional building material that is the final product.

The functional building material of the present invention is obtained by subjecting the inorganic molded body obtained as described above to a temperature of 150 to 200 ° C, preferably 160 to 180 ° C and a pressure of 470 to 1560 kPa, preferably 610. It is obtained by curing under a pressure of -1010 kPa.
Curing can be done in an autoclave. In this step, diatomaceous earth in the inorganic molded body reacts to form a tobermorite-type calcium silicate hydrate having a structure having fine pores grown using the micropores of diatomaceous earth.
If the curing temperature is too low, it does not react sufficiently and the desired pores cannot be obtained. If the curing temperature is too high, a zonotolite form (6CaO · 6SiO ₂ · H ₂ O) is obtained and desired pores cannot be obtained. Further, if the curing pressure is too low, the reaction does not sufficiently occur and the desired pores cannot be obtained. If the curing pressure is too high, it will be in the form of zonotolite and the desired pores will not be obtained.

In the functional building material of the present invention, the calcium silicate hydrate has pores having a pore diameter of 2 to 200 nm, preferably 2 to 50 nm and a water content of 2 to 30% by mass, preferably 2 to 20% by mass. Some calcium silicate hydrates containing free weak alkaline water other than calcium silicate-bound water inside the pores are preferred.
If the pore diameter is too small, the adsorptive capacity is lowered and the resolution of harmful gases is lowered. If the pore diameter is too large, gas dispersion occurs and the gas decomposition ability decreases.
The pore diameter of the pores can be adjusted by the amount of diatomaceous earth, curing temperature / curing pressure.

Moreover, the said moisture content can be adjusted by drying the hardening body after curing, for example at 100-150 degreeC for about 0.5 to 1 hour. If the water content is too low, the content of weak alkaline water is reduced, and the ability of alkali decomposition is reduced. If the moisture content is too high, the strength of the plate itself is lowered, and performance as a building material cannot be secured.
The cured body with the adjusted moisture content is usually ground to a predetermined thickness and trimmed to a predetermined size to obtain a final product (functional building material of the present invention). In addition, it is possible to finish the surface of the final product by using a moisture-permeable paint or cloth.

  Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples.

Example 1
(1) Preparation of raw material composition and slurry In water, pulp composed of 2.7 parts by weight of beaten wood virgin pulp, 1.3 parts by weight of beaten wood recovered pulp and 0.9 parts by weight of unbeaten wood virgin pulp, and length Add 0.8 parts by weight of 3 mm rayon to make a suspension with a solid content concentration of 2% by weight, 2 parts by weight of silica sand, 50 parts by weight of diatomaceous earth, 5 parts by weight of gypsum, 30 parts by weight of slaked lime, sepiolite 1.1 After adding a mass part, 2.7 mass parts of pearlite, and 3.5 mass parts of grinding dust, it stirred and mixed and the slurry for papermaking was obtained.

(2) Manufacture of inorganic moldings (molding)
The slurry was subjected to paper making using a round net paper making machine, and the obtained green plate was pressed to obtain a molded original plate having a thickness of about 15 mm. The molded body original plate was cut to a length of 2420 mm and further pressed to obtain an inorganic molded body having a thickness of about 11.5 mm.

(3) Curing and grinding The inorganic molded body was cured in an autoclave at 180 ° C. and 1003 kPa (10 atm) for 6 hours or more to obtain a cured body. The cured product was taken out from the autoclave and dried at 110 ° C. for 35 minutes, and then the surface was polished and trimmed to obtain the functional building material of the present invention having a width of 900 mm × length of 2420 mm × thickness of 9.5 mm.

Example 2
The function of the present invention is the same as in Example 1 except that the blending amounts of diatomaceous earth, quartz sand, and slaked lime are 35 parts by weight, 37 parts by weight of diatomaceous earth, and 10 parts by weight of slaked lime, respectively. A characteristic building material was obtained.

Comparative Example 1
A commercially available gypsum board (9.5 mmt) was used as the building material of Comparative Example 1.

Comparative Example 2
A building material was obtained by the same composition and manufacturing method as in Example 1 except that the curing of the inorganic molded body in Example 1 was performed at 180 ° C. and atmospheric pressure.
The outline of each example is shown in Table 1.

Evaluation test example 1
Mechanical properties of the functional building materials of the present invention obtained in Examples 1 and 2 and the building materials obtained in Comparative Examples 1 and 2 were evaluated. Table 2 shows the evaluation items of the mechanical characteristics, the measurement method, and the measurement results.

  As is apparent from the measurement results shown in Table 2, the functional building material of the present invention has a bending strength sufficient to withstand the load applied during transportation, and can be sawed. It has excellent properties in terms of workability as an interior material, such as hardness, nailing and sufficient nail pulling resistance.

Evaluation test example 2
About the functional building material of this invention obtained in Example 1, the analysis of the fine structure was performed with the electron microscope and XRD. The electron microscope observation results are shown in FIG. 1, and the XRD results are shown in FIG.
Moreover, the raw material diatomite electron microscope observation result is shown in FIG.

The following can be understood from these measurement results. In the functional building material of the present invention obtained in Example 1, the crater-like uniform shape peculiar to natural diatomaceous earth as shown in FIG. 2 disappears, as is apparent from the electron microscope observation results shown in FIG. However, it is observed that calcium silicate hydrate having a fine pore structure is formed there.
In addition, the functional building material of the present invention obtained in Example 1 has a characteristic tobermorite-type calcium silicate peak confirmed from the XRD results shown in FIG. 3, and from the pore size distribution measurement results shown in Table 1, 2 It is confirmed to have pores of ˜50 nm. The total pore volume of the functional building material of the present invention obtained in Example 2 (diatomaceous earth amount 35 parts by mass) is about 1/2 that of the functional building material of the present invention obtained in Example 1 and Comparative Example 1. The building material (gypsum board) is about 1/10, and the building material (air curing in Example 1) obtained in Comparative Example 2 is about 1/3 (see Table 1).

Evaluation test example 3
For the functional building material of the present invention obtained in Examples 1 and 2 and the building material of Comparative Example 1 (commercial gypsum board), humidity control characteristics were measured by the following method. The measurement was performed using three test pieces of about 300 mm square. The test piece left for 72 hours in an atmosphere of 20 ° C. and 60% relative humidity was transferred to an environment of 20 ° C. and 90% relative humidity, and the weight change (increase) up to 24 hours was measured to examine the moisture absorption characteristics. . Next, the sample was again transferred to an atmosphere of 20 ° C. and a relative humidity of 60%, and the weight change (decrease) up to 24 hours was measured. The measurement results are shown in FIG.

  The following can be understood from the measurement results shown in FIG. The functional building materials of the present invention obtained in Examples 1 and 2 are far superior to the building material of Comparative Example 1 (commercially available gypsum board) in both absorption and desorption rates and absorption and desorption amounts. I understand.

Evaluation test example 4
For the functional building materials of the present invention obtained in Examples 1 and 2 and the building materials obtained in Comparative Examples 1 and 2, the alkaline water dissolution / decomposition characteristics of VOCs and offensive odor substances were measured according to JIS K1475 (activated carbon test method, solvent vapor). The adsorption performance was measured by the following method. For the measurement, a 50 mm square test piece cut out from the final product was used. A test piece, whose side and bottom surfaces were covered with aluminum tape and measured for weight, was inserted into a 1.2 L (liter) sealed container, and adjusted gas was flowed at a flow rate of 2 L / min to adsorb malodorous substances. After 1 hour, the test piece was taken out, the weight was measured, and the adsorption amount was examined. The test piece was again inserted into the sealed container, and the adjustment gas was allowed to flow. This operation was repeated until the amount of increase in the test piece per hour was 5 mg or less, and the increased amount was regarded as the malodorous substance adsorption amount. As the adjusting gas, a gas containing about 1000 ppm of formaldehyde and acetic acid was used. The results are shown in Table 3.

As shown in Table 3, the functional building material of the present invention obtained in Example 1 does not have an increase of 5 mg or less per hour, and the adsorption amount does not saturate even after 8 hours of measurement. adsorption amount after 8 hours formaldehyde 33 g / m ^2, it was the acetic acid 317 g / m ^2. In particular, in the case of acetic acid having infinite water solubility, the amount of adsorption is remarkable, and it is considered that adsorption / weak alkaline water dissolution / decomposition occurs.
The building material obtained in Example 2 (diatomaceous earth amount 35 parts by mass) has a formaldehyde adsorption amount of 24 g / m ² after 8 hours, and the building material of Comparative Example 1 (commercial gypsum board) that does not exhibit alkali is the first In 1 hour, the increase was saturated to 5 mg or less, and the amount of formaldehyde adsorbed was 5.5 g / m ² .
Also, building materials obtained in Comparative Example 2 are formaldehyde adsorption amount 14 g / m ^2, was less than half of the acetic acid 64 g / m ² as in Example 1.

Evaluation test example 5
In the functional building material of the present invention, the following test was conducted in order to confirm the influence of the presence of free water on the adsorption / decomposition ability of VOC.
Two test pieces of the functional building material of the present invention obtained in Example 1 were prepared, and one of them was completely dried at 105 ° C. Another test piece had an equilibrium water content at 20 ° C. and a relative humidity of 60%. The amount of acetic acid gas adsorbed was measured by the measurement method of Evaluation Test Example 4 described above for these two test pieces.
In any of the test pieces, the increase per hour was not less than 5 mg after 8 hours of measurement. Acetate gas adsorption amount after measuring 8 hours, 52 g / m ² in the absolute dry products with no free water in the test piece, the equilibrium moisture content products containing free water in the test piece was 317 g / m ^2, the free In the absence of water, it was found that adsorption / decomposition ability was poor. This indicates that the presence of free water is extremely important for gas decomposition.

It is an electron micrograph (magnification 20000 times) which shows the electron microscope observation result of the functional building material of this invention obtained in Example 1. FIG. It is an electron micrograph (magnification 20000 times) which shows the electron microscope observation result of the raw material diatomaceous earth used in Example 1. It is a figure which shows the XRD measurement result of the functional building material of this invention obtained in Example 1. FIG. It is a figure which shows the humidity control characteristic (temporal change of moisture absorption / release amount) of each building material measured in the evaluation test example 3.

Claims (4)

  A structure having fine pores obtained by curing an inorganic molded body obtained by molding a raw material containing 30 to 75% by mass of diatomaceous earth at a temperature of 150 to 200 ° C. and a pressure of 470 to 1560 kPa. Functional building material consisting of calcium silicate hydrate.   The calcium silicate hydrate having a structure having fine pores is a calcium silicate hydrate having pores with a pore diameter of 2 to 200 nm and a water content of 2 to 30% by mass. The functional building material according to claim 1, wherein the pore contains free weak alkaline water other than calcium silicate-bound water.   The said inorganic molded object is 30-75 mass% of diatomaceous earth, 20-40 mass% of slaked lime, 1-10 mass% of silica sand, 1-10 mass% of gypsum, 1-10 mass% of pulp, and 0.1-3 mass% of fibers. The functional building material according to claim 1, wherein the functional building material is formed by papermaking using a raw material.   The functional building material according to claim 3, wherein the raw material further contains 10% by mass or less of pearlite.