JP3212587B1 - Humidity control building materials - Google Patents

Abstract

An object of the present invention is to provide a humidity control building material which is excellent in moisture absorption / desorption, moisture permeability, and nonflammability, and has sufficient strength to be used as a building material. SOLUTION: A molded article whose main components are calcium carbonate and amorphous silica is produced by a carbonic acid curing reaction. The molded product has a specific surface area of 80 as measured by a nitrogen gas adsorption method.
２５０250 m ² / g, average pore diameter 1.5-30.0 n
m and its thermal conductivity is 0.4 W / m
K or less.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a humidity control building material which is an inorganic material having excellent non-combustibility and has a function of controlling indoor humidity.

[0002]

2. Description of the Related Art Conventionally, plasters containing calcium carbonate as a main component have been used as building materials having a humidity control property. Plaster has been used for a long time as a humidity control building material, but actually has a small amount of moisture absorption and desorption. Then, in order to prevent cracks due to drying shrinkage, it is necessary to increase the thickness or to mix a large amount of reinforcing fibers such as soot. However, there is a problem that the moisture absorption and desorption increases as the thickness increases, but the moisture permeability decreases.
Humidity control performance does not increase.

[0003] Plaster containing diatomaceous earth containing amorphous silica is used as a material for improving the humidity control property of the plaster.
There is a cement plate with diatomaceous earth containing amorphous silica inside.However, diatomaceous earth is deteriorated by plaster and alkali components of cement, lowering the high specific surface area that diatomaceous earth originally has, and has a sufficient humidity control effect. Not.

Further, building materials generally require strength, dimensional stability and incombustibility, but the above-mentioned materials have low strength in spite of their weight. That is, the specific strength is low. In addition, the length change rate due to water absorption is large, and cracks occur and dimensional stability is poor. When a large amount of soot is mixed in to prevent cracks, there is a problem in that the incombustibility is reduced.

[0005]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems, and is a non-flammable humidity-controlling building material having an excellent moisture absorption / desorption amount, excellent moisture permeability, and sufficient strength to be used as a building material. The purpose is to provide.

[0006]

SUMMARY OF THE INVENTION The humidity control building material of the present invention is a molded article produced by a carbonic acid curing reaction, which comprises a molded article whose main components are calcium carbonate and amorphous silica. In the building material, the specific surface area by the nitrogen gas adsorption method is 80 to 250 m ² / g, the average pore diameter is 1.5 to 30.0 nm, and the thermal conductivity is 0.4.
It is characterized by being at most W / mK. Here, the thermal conductivity refers to a value measured according to JIS A1412 “Method of measuring thermal conductivity and thermal resistance of thermal insulation”.

[0007] It is generally said that the relative humidity condition for human beings to live comfortably is between 40 and 70%. In order to maintain the room humidity in the meantime, a humidity control building material exhibiting excellent humidity control performance in that range is suitable.
Also, when viewed from the viewpoint of surface physics, a humidity control material has a high ability to adsorb water vapor in the air by a capillary tube of the material in a high humidity atmosphere and release the adsorbed moisture into the air in a low humidity atmosphere. It can be said that it is a material.

As a result of intensive studies on what kind of material can actually be an excellent humidity control building material, the present inventors have found that a molded product produced by a carbonation hardening reaction, the main components of which are calcium carbonate and amorphous It has been found that in the case of porous silica, the average pore diameter and the specific surface area greatly affect the humidity control performance. That is, the humidity is adjusted by adsorbing / desorbing the water vapor to / from the minute void walls inside the material, so that a material having fine pores and a larger specific surface area has a higher moisture absorption / release amount. However, when the pore diameter is extremely small, it becomes difficult to release water vapor, and moisture is absorbed but not released, so that the specific surface area is 80 to 25.
0 m ² / g and the average pore diameter is 1.5-30.0
The range of nm is optimal.

[0009] Further, it has been found that thermal conductivity is also an important factor as a humidity control building material. If this is used, for example, as a wall material, in winter when the outside of the room is cooled by the outside air, if the thermal conductivity is high, the inside of the room will also be cold, and dew condensation may occur on the surface of the inside of the room. In particular, such a phenomenon is likely to occur when the humidity control building material is attached to a concrete wall having low heat insulation. If dew forms on the surface of the humidity control building material, the dew water will be absorbed inside, but because the dew water is a liquid rather than water vapor, it will enter the material more slowly and excess moisture will be distributed to the surface layer Will be. This should be a problem for humidity-controlled building materials. This is because if water as a liquid is excessively concentrated on the surface layer, the rate of absorption of water into the material will be reduced, and the subsequent humidity control will be reduced. Furthermore, the water present in the liquid state promotes the occurrence of mold, and may be undesirably aesthetically and healthily. The weather conditions in Japan and the wall structure of houses have shown that when wood is used for interior finishing, surface condensation is unlikely to occur. The thermal conductivity of commonly used wood is measured according to JIS A1412 “Method of measuring thermal conductivity and thermal resistance of thermal insulation”.
It is at most 0.4 W / mK (maple etc.). Therefore,
As a result of studying the humidity-controlling building material of the present invention having a water content of 0.4 W / mK or less, it was found that the humidity-controlling material was very excellent. If the temperature exceeds this, when the temperature difference is large on both sides of the wall, dew condensation water is generated on the surface layer, and the subsequent hygroscopicity rapidly decreases.

[0010] The composition of the molded product produced by the carbonic acid curing reaction is composed of 15% to 65% of calcium carbonate, 15% to 45% of amorphous silica, and one or both of an aggregate and a porous material. It is preferred to configure. Further, it is more preferable to include vaterite in calcium carbonate. This is because these compositions result in a material having a very large specific surface area having micropores of several nm as a whole. In addition, the molded article may contain 60% or less of one or both of the aggregate and the porous material. If the porous material is 60% or less, the humidity control performance is improved while maintaining sufficient specific strength. Can be.

[0011] In addition, by setting the aggregate to 60% or less and the average particle size of the aggregate to 10 µm or more, JIS A54
The length change rate due to water absorption shown in No. 30 can be set to 0.25% or less, and the dimensional stability can be excellent. The length change rate due to water absorption is JIS A5
This is because, as indicated by 430, 0.25% or less is desirable. Here, as the aggregate, silica stone powder, feldspar powder, mica, artificial lightweight aggregate, and the like can be used.
As the porous material, a material containing alumina silicates, a pumice stone, a balun-like filler, or the like can be used. In addition, since calcium carbonate as a main component causes an endothermic reaction when heated at a high temperature of 700 ° C. or more and dissociates into carbon dioxide and calcium oxide, it is also a building material excellent in noncombustibility.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION As a starting material of a humidity control building material according to the present invention, a calcareous raw material powder and a siliceous raw material powder are used, and these are mixed with an arbitrary molar ratio of calcium and silica components (CaO / Si).
O ₂ ). Excess SiO ₂ does not react in a hydration reaction or an autoclave reaction described later and remains as aggregate. The average diameter of the remaining aggregate is desirably 10 μm to 3 mm. As the calcareous raw material powder, one or a mixture of two or more of Portland cement such as ordinary cement and early-strength cement, slaked lime, quick lime and the like can be used. In addition, as the siliceous raw material powder, one or a mixture of two or more of silica sand, silica powder, coal ash, silica gel, cristobalite, diatomaceous earth and the like can be used. However, one or both of the aggregate and the porous material may be separately mixed as needed by 60% or less.

The aggregate that can be mixed is, for example, silica powder, feldspar powder, mica, artificial lightweight aggregate, and the like, and in this case, the average particle size is desirably 10 μm to 3 mm. Examples of the porous material include those containing alumina silicates, pumice, and balun-like filler. In addition, the addition of the aggregate and the porous material before the reaction or
It may be before pressure molding described below. It is subjected to a hydration reaction or an autoclave reaction to produce a calcium silicate-based hydrate. For example, at 180 ° C., the main component is tobermorite, and a powder can be synthesized in which the surplus siliceous raw material becomes an aggregate. This is press-formed into a plate shape using a press machine. The pressure is desirably 5 to 30 MPa. In addition, before performing pressure molding, 0.1-5.0% of reinforcement fiber, 0.01
A chemical adsorbent having a deodorant effect of 0.01 to 5% may be mixed with an inorganic pigment of 5 to 5%. Further, for the purpose of increasing the strength of the material, Portland cement such as ordinary, fast, moderate heat, white, or γ-C ₂ S is mixed in so that the calcium carbonate content of the material after carbonation hardening does not exceed 65%. Is also good. When using Portland cement,
Some or all of the cement may have undergone a hydration reaction.

Next, this is reacted and cured in a closed container using carbon dioxide gas. The reaction conditions are as follows.
C. and a carbon dioxide concentration of 2 to 100% are industrially preferable. For example, carbon dioxide in exhaust gas generated during combustion can be used. By the carbonic acid curing reaction, the calcium component in the tobermorite escapes as calcium carbonate, and amorphous silica having many pores is formed. This porosity affects not only moisture absorption / release properties but also thermal conductivity. In addition, calcium carbonate produces not only calcite as a main component but also fine vaterite. These products result in materials with very large surface areas having micropores of a few nm.

In addition, in addition to tobermorite, calcium silicate-based hydrates such as zonotolite and CSH or waste materials containing these as a main component can be used for the production. For example, lightweight cellular concrete powder, crushed products of cement secondary products such as ceramic sizing, waste concrete, cement sludge, and the like can be used. In addition, since this material has a sufficient specific strength, it can be used as a building material having a humidity control property. And
The ratio of the main component is 15% to 65% calcium carbonate.
%, And amorphous silica is desirably 15% to 45%. In addition, it is desirable that one or both of the aggregate and the porous material be contained at 60% or less, and the average particle size of the aggregate be 10 μm or more.

The humidity control building material of the present embodiment has a moisture conductivity of 8
ng / (ms · Pa) or more and good response to humidity change. FIG. 1 shows an example of the pore size distribution of the humidity control building material according to the present invention. The pore size distribution is characterized by having peaks on both sides of the average pore size. The pore diameter has a function of increasing the moisture conductivity, and a high humidity control property can be obtained by the synergistic effect.

In addition, as an evaluation in an actual humidity changing atmosphere, the humidity of 70% and 30% were measured under a constant temperature condition of 25 ° C. for 24 hours.
Were tested for 48 hours per cycle for time increments held, by measuring the weight change of the material, it was measured absorption and wet weight per unit area, there per 80 g / m ² or more per unit area Hygroscopic amount is large. Further, as a parameter of the humidity control performance, the amount of moisture absorption / release alone is not sufficient, and the responsiveness to changes in ambient humidity is also an important factor. The factor can be evaluated by moisture conductivity. A material having a high moisture conductivity has a quick response to a change in humidity, and is preferable as a humidity control building material. However, a material having too high a moisture conductivity generally has many continuous voids and a low density, so that the amount of moisture absorbed and released and the strength are often low.

For example, 0.3 m width × 0.6 m length × 0.0
For building materials of 06m thickness and 0.3m width cantilever
The bending strength (kg
/ M ²) / Bulk density (kg / m³)
About 180m, but this humidity control building material
Since it has a specific strength, the strength is sufficient. Desired
The bulk density is 500-2000kg / m³About
You.

[0019]

Example 1 Using calcareous raw material powder and siliceous raw material powder,
The powder was adjusted so that CaO / SiO ₂ became 0.25. It was placed in an autoclave at 180 ° C for 4 hours.
The synthesis of time tobermorite was performed. The resulting powder was molded using a press molding machine at a molding pressure of 20 MPa and a pressure of 300 mm.
A plate having a thickness of 300 mm x 12 mm was formed.

By using a commercially available carbon dioxide gas by the above-mentioned method and subjecting it to carbonation hardening, calcium carbonate is reduced to 29%.
%, Amorphous silica 21%, and aggregate 49%. In the analysis of the components, calcium carbonate was calculated from the amount of carbon dioxide gas generated by dissolving the sample with 6N hydrochloric acid. Amorphous silica was calculated from the amount dissolved in 2N sodium hydroxide.

For the aggregate, first, a sample is dissolved in 6N hydrochloric acid, and then the solution is filtered and sufficiently washed with warm water. Next, the residue on the filter paper is dissolved with 2N sodium hydroxide, neutralized with hydrochloric acid, filtered, and sufficiently washed with warm water. Finally, aggregate remaining on the filter paper was determined. The average particle size of the aggregate was determined by measuring the particle size distribution using a SALD-2000 particle size distribution measuring device (manufactured by Shimadzu Corporation). As a result, the average particle size of the aggregate was determined to be 68 μm. Next, the specific surface area and the average pore diameter were measured using a nitrogen adsorption method, specifically, Micromeritex Asap 2400 (manufactured by Shimadzu Corporation). The specific surface area was 92 m ² / g, and the average pore diameter was 92 m ² / g. Was 9.5 nm.

Next, when the moisture conductivity was measured by a method according to JIS A1324, it was 10.4 ng / (m
S · Pa). When the thermal conductivity was measured by a method according to JIS A1412, it was 0.36 W / mK.
Met. Next, in order to measure the amount of moisture absorbed / released, a test in which the humidity was changed at constant intervals under a constant temperature was performed as follows. First, the material was subjected to a moisture-proof treatment with an aluminum seal on the other five surfaces so that only one surface of a 300 mm square surface had a humidity control effect. At a constant temperature of 25 ° C in an environmental tester,
The humidity was maintained at 30%, and the specimen was allowed to stand until there was no change in weight.

Next, the humidity was changed to 70%, kept for 24 hours, and the change in weight due to moisture absorption when the humidity increased was measured.
%, And held for 24 hours, and a 48-hour one-cycle test was performed in which the change in weight during moisture release due to a decrease in humidity was measured, and the amount of moisture absorbed and released per unit area of the test specimen was measured. The amount of moisture absorption / release was determined by the following equation. Moisture absorption / desorption amount = ((weight change at the time of moisture absorption + weight change at the time of moisture release)
/ 2) / Specimen area The result was 123 g / m ² . Then add 100
mm × 25 mm × 12 mm (thickness), the bulk density and bending strength were measured, and the specific strength was calculated.
It was 32 m. Finally, the length change rate due to water absorption was measured by a method according to JIS A 5430.
14%.

Table 1 shows the above results. FIG. 1 shows a distribution diagram of the pore diameter, which is characterized by peaks on both sides of the average pore diameter of 9.5 nm. The pore diameter smaller than the average increases the specific surface area, and the large pore diameter indicates the moisture conductivity. And a high humidity control was obtained by the synergistic effect.

[Table 1]

Example 2 Using calcareous raw material powder and siliceous raw material powder,
The powder was adjusted so that CaO / SiO ₂ became 0.4. This was subjected to carbonation hardening according to the procedure shown in Example 1, and calcium carbonate was 40%, amorphous silica was 29%, and aggregate was 2%.
A 9% humidity controlled building material was produced. Various measurements were performed by the method described in Example 1. Table 1 shows the above results.

[0025]

Example 3 Using calcareous raw material powder and siliceous raw material powder,
The powder was adjusted so that CaO / SiO ₂ became 0.6. This was subjected to carbonation hardening according to the procedure shown in Example 1, and calcium carbonate was 50%, amorphous silica was 36%, and aggregate was 1%.
A 2% moisture-control building material was produced. Various measurements were performed by the method described in Example 1. Table 1 shows the above results.

[0026]

Example 4 Using calcareous raw material powder and siliceous raw material powder,
The powder was adjusted so that CaO / SiO ₂ became 0.8. This was subjected to carbonation hardening according to the procedure shown in Example 1, and calcium carbonate was 57%, amorphous silica was 41%, and aggregate was 1%.
% Humidity-control building material was manufactured. Various measurements were performed by the method described in Example 1. Table 1 shows the above results.

[0027]

Example 5 Using the same calcareous raw material powder and siliceous raw material powder as in Example 4, the powder was adjusted so that CaO / SiO ₂ became 0.8. 14 parts by weight of a fine silica powder having an average particle diameter of 8 μm was mixed with 100 parts by weight of this powder with a mixer. This is subjected to carbonic acid curing according to the procedure shown in Example 1,
Humidity-control building materials with 50% calcium carbonate, 36% amorphous silica and 12% aggregate were produced. Various measurements were performed by the method described in Example 1. Table 1 shows the above results.

[0028]

Example 6 Using the same calcareous raw material powder and siliceous raw material powder as in Example 1, the powder was adjusted so that CaO / SiO ₂ became 0.25. To 100 parts by weight of this powder, 30 parts by weight of a clay having a particle size of 74 μm or less was mixed as a porous material powder with a mixer. This was subjected to carbonation hardening according to the procedure shown in Example 1 to produce a humidity control building material in which calcium carbonate was 22%, amorphous silica was 16%, aggregate was 37%, and porous material was 23%. Various measurements were performed by the method described in Example 1. Table 1 shows the above results.

[0029]

Example 7 Using the same calcareous raw material powder and siliceous raw material powder as in Example 4, the powder was adjusted so that CaO / SiO ₂ became 0.8. Clay having a particle size of 74 μm or less as a porous material powder was mixed with 100 parts by weight of this powder using a 140 part by weight mixer. This was subjected to carbonation hardening according to the procedure shown in Example 1 to produce a humidity control building material having 23% of calcium carbonate, 17% of amorphous silica, 0.4% of aggregate, and 58% of porous material. . Various measurements were performed by the method described in Example 1. Table 1 shows the above results.

[0030]

Example 8 Using the same calcareous raw material powder and siliceous raw material powder as in Example 1, the powder was adjusted so that CaO / SiO ₂ became 0.25. To 100 parts by weight of the powder, 10 parts by weight of ordinary Portland cement was mixed with a mixer. This was subjected to carbonation hardening according to the procedure shown in Example 1, and calcium carbonate was 60%, amorphous silica was 17%, and aggregate was 2%.
A 3% moisture conditioning building material was produced. Various measurements were performed by the method described in Example 1. Table 1 shows the above results.

In Examples 1 to 8, the specific surface area is 80 to 250 m ² / g, and the average pore diameter is 1.5 to 3
0.0 nm, the moisture conductivity is 10.0 ng /
(M · s · Pa) or more, the moisture absorption / desorption amount was 80 g / m ² or more, the humidity control performance was high, and the humidity control building material with sufficient strength to satisfy the specific strength of 180 m or more was obtained. In addition, the thermal conductivity was 0.4 W / mK or less in both cases, and even when used in an environment having a large temperature difference between the inside and outside, no deterioration in humidity control due to dew water was caused. Moreover, the average particle size of the aggregate was 10 μm or more, and the ratio of change in length due to water absorption was 0.25% or less.

[0032]

Comparative Example 1 To 7 kg of calcium hydroxide and 3 kg of diatomaceous earth, 5.5 kg of water and 0.3 kg of forefoot were added and kneaded. Put it in a mold, 300mm x 300mm x 1
It was processed into a test specimen of 2 mm (thickness), 100 mm × 25 mm × 12 mm (thickness). Each test specimen was cured for 4 weeks, and various measurements were performed by the method shown in Example 1.

As a result, the specific surface area was as small as 75 m ² / g.
Since the average pore diameter is as small as 1.4 nm, the moisture conductivity is as small as 7.3 ng / (ms · Pa), and the moisture absorption / release amount is 3
As low as 8 g / m ² , the humidity control performance was poor. The specific strength is 5
It was as small as 5m. In addition, since the average particle size of the aggregate was as small as 9 μm, the rate of change in length due to water absorption was as large as 0.4%, indicating that it was difficult to use as a humidity control building material. Table 1 shows the above results.

[0034]

Comparative Example 2 Portland cement 7 kg and diatomaceous earth 3 k
6.5 kg of water was added to and kneaded with the mixture. Put it in a mold, 300mm x 300mm x 12mm (thickness), 1
It was processed into a test specimen of 00 mm × 25 mm × 12 mm (thickness). Each test specimen was cured for 4 weeks, and various measurements were performed by the method shown in Example 1.

As a result, the specific surface area was as small as 60 m ² / g, and the average pore diameter was as small as 1.3 nm. Further, the moisture conductivity was as large as 17.5 ng / (m · s · Pa), but the moisture absorption / desorption amount was as low as 27 g / m ² and the humidity control performance was poor. Although the specific strength was sufficiently high at 425 m, the average particle size of the aggregate was as small as 8 μm. Therefore, the shrinkage was large enough to cause cracks during drying, and the length change rate due to water absorption could not be measured. That is, it turned out that it is difficult to use as a humidity control building material. Further, the thermal conductivity is 0.46 W / mK.
In Comparative Examples 1 and 2 described above, when this is used for the outer wall of a building, for example, when the outside air is at a low temperature in winter, the inner wall surface is also cooled, and surface dew condensation is expected to occur on the indoor side. .

[0036]

Comparative Example 3 Using the same calcareous raw material powder and siliceous raw material powder as in Example 1, the powder was adjusted so that CaO / SiO ₂ became 0.25. Alumina powder having a particle size of 100 μm or less is used as an aggregate for 20 parts by weight of the powder.
The mixture was mixed with a weight part mixer. This was subjected to carbonation hardening according to the procedure shown in Example 1 to produce a humidity control building material having 24% calcium carbonate, 18% amorphous silica, and 58% aggregate. Various measurements were performed by the method described in Example 1.
Table 1 shows the above results. As a result, the specific surface area and the average pore diameter were 82 m ² / g and 9.9 nm, respectively.
The moisture conductivity is 9.5 ng (m · s · Pa), and the moisture absorption / desorption amount is 102 g / m ^2, and the humidity control performance is high. However, the thermal conductivity is 0.62 W / mK, and when it is used as a wall material for a building, it is expected that, for example, when the outside air temperature is low in winter, the inner wall surface is also cooled and surface dew condensation occurs on the indoor side. Is done.

[0037]

As described above, according to the present invention, it is possible to obtain a moisture-control building material having excellent humidity control properties, sufficient strength and excellent nonflammability, and a heat conductivity of 0.4 W / mK or less. Therefore, there is an effect that the surface dew condensation hardly occurs and the humidity control can be stably exhibited.

[Brief description of the drawings]

FIG. 1 is a graph showing a pore size distribution in Example 1 of the present invention.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Kenji Inagaki 2035 Shimo-machi, Shioi-machi, Owariasahi-shi, Aichi Prefecture Inside the Building Materials Research Laboratory (72) Katsumi Hirabayashi 2035, Shimoi-machi, Shioi-machi, Owariasahi-shi, Aichi, Japan Within the Technical Research Institute (72) Inventor Masashi Sakashita 2035, Shimoi-machi, Shioi-machi, Owariasahi-shi, Aichi Prefecture, Japan Construction Materials Research Laboratory (56) References JP-A-7-284628 (JP, A) JP-A-8-81284 (JP) , A) JP-A-7-25679 (JP, A) JP-A-9-12404 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C04B 28/18-28/22 C04B 40/02 B01D 53/28 E04B 1/64 C04B 28/00 C04B 28/10 C04B 12/00

Claims (5)

(57) [Claims] 1. A humidity control building material comprising a molded product produced by a carbonic acid curing reaction and comprising calcium carbonate and amorphous silica as main components, having a specific surface area of 80 to 250 m by a nitrogen gas adsorption method. ² / g, an average pore diameter of 1.5 to 30.0 nm, and a thermal conductivity of 0.4 W / mK or less. 2. The humidity control building material according to claim 1, wherein the specific strength is 180 m or more. 3. The molded product contains 15% of calcium carbonate.
3. The humidity control building material according to claim 1, wherein the humidity controlling material comprises about 65%, about 15% to about 45% of amorphous silica, and one or both of an aggregate and a porous material. 4. 4. The humidity control building material according to claim 1, wherein said calcium carbonate contains vaterite. 5. The humidity control building material according to claim 3, wherein one or both of the aggregate and the porous material are contained in an amount of 60% or less.