JP2733186B2 - Manufacturing method of porous building materials - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a porous building material used as a building member such as a wall material, and more particularly to a method for producing a porous building material having both a soundproofing property and an electromagnetic wave shielding property.

[0002]

2. Description of the Related Art As various electronic devices including computers have been widely used in various situations, noise problems caused by karaoke devices and air conditioners,
Electromagnetic interference due to OA equipment and home electronic equipment has become apparent. Since it is extremely difficult to completely prevent the generation of noise and electromagnetic waves from such equipment, it is necessary to improve the soundproofing and electromagnetic shielding of buildings such as houses, and to deal with noise and electromagnetic interference. ing.

Conventionally, building members for the purpose of soundproofing include, for example, cloth cloth, rock wool (glass wool).
Materials, such as foam concrete material is known, as a member for shielding electromagnetic waves, for example, zinc sprayed material,
Sputtering shield materials, conductive plastic shield materials, and the like are known. However, each of these materials individually functions as a soundproofing material or an electromagnetic wave shielding material, and when it is required to satisfy both functions at the same time, for example, sticking and laminating each member. They were used in appropriate combinations.

[0004]

However, when the members manufactured separately for the respective purposes are attached as described above, (1) the thickness and weight of the material are limited by the soundproofing material and the electromagnetic wave shielding. For example, if it is used as a wall material, the outer dimensions must be increased or the inner dimensions must be reduced, and if it is used as a ceiling material, a reinforcing material or the like for supporting the increased weight is required. For this reason, there has been a problem that the degree of freedom in design may be reduced, and the burden on structure and construction may increase. In addition, (2) work such as sticking is required, which is disadvantageous in cost.

[0005] Against this background, there has been a demand for an integrated building material having both soundproofing and electromagnetic wave shielding properties. However, from the usage as a building material, it is required that (a) be strong enough to withstand a little rough handling, (b) be homogeneous and not deteriorate over a long period of time, and (c) be supplied at a low price. As a result, none of the building materials having both the soundproofing property and the electromagnetic wave shielding property satisfy these (a) to (c).

In order to obtain such a material having both soundproofing and electromagnetic wave shielding properties, for example, the surface of a porous material is
Although a technique of attaching a metal foil such as an aluminum foil is also conceivable, it is not practical because, for example, detachment of the foil due to deterioration of the adhesive layer is likely to occur.

It is also conceivable to apply a metal coating to the surface of a porous material or the like, and examples thereof include a plating method and a sputtering method. The plating method includes a well-known electrolytic plating method (electroplating method) and an electroless plating method.

In the electroplating method, the base material must be a conductor such as a metal in order to perform plating by electric energy, and cannot be applied to an insulator such as concrete. On the other hand, since the electroless plating method is a plating method that uses chemical energy such as a reducing action,
Plating is possible even if the base material is an insulator such as plastic. That is, it is characterized in that a metal such as copper or nickel is formed into a film on the surface of the base material by a chemical change. However, the quality of the film formed by this method has a disadvantage that it is easily affected by the temperature of the plating solution and the contamination of the base material surface. Usually, in the electroless plating method, the plating solution is heated in order to promote a chemical change, but the temperature of the plating solution may not be constant due to, for example, a difficulty in uniforming the temperature distribution on the surface of the base material. . In such a case, the chemical change of the plating solution becomes non-uniform, and the metal film formed on the surface of the base material may become dotted island-like spots. In addition, if the surface of the base material is not sufficiently cleaned, the formation of a film is hindered in a stained portion, and a spot-like metal film may be generated as described above. In such a spot-like metal coating portion, the adhesion tends to be significantly reduced. Therefore, in the electroless plating method, the adhesion of the metal film is unstable, and it is difficult to apply the material to a material which is likely to be rough, such as a building member.

In the sputtering method, electrons accelerated by a high voltage are caused to collide with a target metal such as gold or silver, thereby solidifying metal particles such as atoms and ions that have been knocked out on the surface of the base material. . This process occurs one after another, and the metal is deposited in layers to form a coating. Since this sputtering is performed in a vacuum vessel, a very good quality coating can be obtained without inhibition by air molecules. This sputtering method is a method that is very excellent in the adhesion of the coating.
However, the material to be coated must be processed in a high vacuum, which requires a complicated vacuum apparatus, and the material cost is high because gold or silver, which is easily turned into plasma, is used as a sputtering target. For example, this method is used only for small, high-value-added materials such as the inside of a housing of precision electronic equipment, and is difficult to apply to equipment such as building materials in terms of equipment and cost.

As described above, for example, in the case of a plastic material, a sputtering method or a plating method may be used depending on the use or importance of the material. It can be seen that the method described above does not make any use for a member that is likely to be damaged.

The present invention has been completed as a result of repeated research on such a background, and has both soundproofing performance and electromagnetic wave shielding performance, and has the above (a) to (c).
It is an object of the present invention to provide a method for producing a porous building material satisfying the following.

[0012]

The gist of the present invention to solve such a problem is to provide a compound or a compound which generates a conductive substance by thermal decomposition on the surface of an inorganic porous material. A method for producing a porous building material, comprising applying a solution of the compound and thermally decomposing the applied compound to form a conductive layer on the surface of the porous material.

Hereinafter, the present invention will be described in more detail. The inorganic material-based porous material used in the present invention, for example, such as porous ceramics and cellular concrete,
It is a porous material such as ceramics and concrete, and any known porous material can be used without particular limitation.

A compound (hereinafter, simply referred to as a thermally decomposable compound) which thermally decomposes to form a conductive substance such as a metal, or a solution of the compound is applied to the surface of the porous material. Note that a plurality of types of thermally decomposable compounds may be used in combination. As such a thermally decomposable compound,
For example, metal chlorides, alkoxides, chelate compounds, organic metals and the like can be mentioned.

Among these thermally decomposable compounds, tin chloride, tetrabutoxy tin, tetramethoxy tin, etc., because the adhesion of the conductive substance generated by thermal decomposition to the surface of the base material (porous material) is strong. And compounds containing tin such as tetraethoxytin and tetra-i-propoxytin, and mixtures of any one or more of these with triethoxyantimony or tri-n-propoxyantimony (antimony alkoxide). In particular, when a mixture of the above-mentioned tin compound and an antimony compound or an indium compound is used, the conductivity of the formed conductive layer becomes more stable and good.

The above-mentioned solution of the thermally decomposable compound includes, for example, an aqueous solution, a solution of alcohol or another organic solvent. The solvent, the concentration, and the like are not particularly limited, and may be appropriately set according to various conditions such as the type of the thermally decomposable compound to be used and the thickness of the conductive layer to be formed.

The method of applying the thermally decomposable compound or a solution thereof to the surface of the porous material is not particularly limited, and an appropriate means such as dipping, spraying, or brushing can be employed.
At this time, a viscosity modifier may be added to the thermally decomposable compound or a solution thereof depending on the coating method.

The amount of the thermally decomposable compound or its solution applied (the thickness of application) is an amount sufficient to form a conductive layer that satisfies the electromagnetic wave shielding required for a porous building material. Since it varies depending on the type of the decomposable compound, the concentration in a solution, and the like, it is not determined uniformly. For example, when using tin chloride or tetrabutoxy tin,
Although it depends on the required performance of the porous building material, the amount of tin to be applied is preferably 1.6 to 16 g per 1 m ^{2 of} the coated surface. Further, it is preferable that the application of the thermally decomposable compound to the surface of the porous material is performed as uniformly as possible. However, the fact that there is some unevenness does not mean that the generated conductive layer has insufficient electromagnetic wave shielding performance.

For example, the surface of a cellular concrete material or the like is usually not smooth but has fine irregularities, but since a solution such as an aqueous solution has a property of penetrating from the material surface to the inside of the material, it is not only on the surface but also on the surface. The thermally decomposable compound can penetrate into the interior near the surface of the material. When the thermally decomposable compound penetrates as described above, a conductive substance can be generated not only on the surface of the porous material but also inside the vicinity of the surface, and the electromagnetic wave shielding property is improved.

The application of the thermally decomposable compound or a solution thereof to the surface of the porous material may be performed entirely or partially according to the electromagnetic wave shielding performance required depending on the use and installation conditions of the porous building material. For example, if a porous building material is used for the wall material, it may be applied to both surfaces or one surface corresponding to the inner and outer wall surfaces according to the required degree of electromagnetic wave shielding. In this case, usually only one-sided coating is sufficient, but for example, when the porous building material is easily chipped, the both-sided coating is performed, and even if a part is missing, a predetermined electromagnetic wave shielding performance can be secured. . at the same time,
There is also a merit that the electromagnetic wave shielding effect is enhanced by the double conductive layer.

The thermally decomposable compound or the porous material coated with the solution is heated, for example, in an electric furnace to thermally decompose the thermally decomposable compound. It is formed on the surface of the porous material. The temperature required for the thermal decomposition reaction of the thermally decomposable compound varies depending on the type of the thermally decomposable compound and the mixing ratio of auxiliaries, but if tin chloride or tetrabutoxy tin is used, about 200 to A temperature range of 600 ° C. is sufficient.

It is also possible to heat the porous material in, for example, an electric furnace and spray a thermally decomposable compound or a solution thereof. According to this method, since the porous material is heated, a thermal decomposition reaction occurs almost simultaneously with spraying, and the conductive layer is formed in a very short time of about 2 to 3 seconds. Further, since the temperature of the porous material is slightly lowered by spraying, it is preferable to heat the porous material to a temperature that allows for this. However, in the case of using this method, spraying a high concentration solution of a thermally decomposable compound may leave a reaction residue such as an organic substance in a formed conductive film. .

In the case of spraying under heating, the thermal decomposition reaction is completed in a short time as described above. However, in the case of heating the porous material after applying the thermal decomposable compound by brushing or spraying, the heating time is as follows. Although it depends on the type and the mixing ratio of the thermally decomposable compound, about 15 to 60 minutes is sufficient. However, the temperature range and heating time shown here are examples,
The present invention is not limited to this range.

Although the thickness varies depending on the electromagnetic wave shielding performance required for the porous building material, the thickness of the conductive layer formed by thermal decomposition is in the range of about 0.4 to 4 μm. This thickness is extremely thin as compared with the thickness (10 to 100 mm) of a porous material used as a wall material, for example.
Therefore, the increase in thickness due to the formation of the conductive layer on the porous material does not hinder the use as a building material.

Since the inorganic porous material used in the present invention is an inorganic material such as ceramics or concrete, it has excellent heat resistance and can sufficiently withstand heating for thermal decomposition. it can. Also, as is well known,
The inorganic material-based porous material has a property that it is mechanically strong and does not deteriorate over a long period of time, and the above property is maintained even after the conductive layer is formed to be a porous building material.

Since the thermally decomposable compound or its solution is applied to the surface of the porous material and the conductive layer is formed by a thermal decomposition reaction by heating, the procedure is simple, and a complicated device such as a vacuum device is required. do not do. In addition, as an effect of the heat treatment, an effect is provided in which the porous material and the conductive layer are firmly bonded. This is because atoms on the surface of the porous material are activated in advance by heating, and are easily bonded to metal atoms and the like forming the conductive layer. In other words, in electroless plating, the plating layer is formed so as to spread in the horizontal direction from nuclei formed on the surface of the base material in a dotted manner, so that the bonding in the vertical direction (perpendicular to the surface of the base material) is weak. According to the processing
The longitudinal bonding force between the conductive layer and the porous material is extremely strong. Therefore, the adhesion of the conductive layer becomes extremely high, and the conductive layer does not peel even in a rough working environment such as a construction site. Further, for example, even after being applied as a wall material, the conductive layer does not peel off, and the electromagnetic wave shielding performance can be exhibited for a long period of time.

The electromagnetic wave shielding effect of the conductive layer formed in this manner changes depending on the thickness of the conductive layer and the frequency of the electromagnetic wave, but is usually calculated by the following formula (1).
~ 70 (dB) is obtained.

[0028]

## EQU1 ## SE (dB) = 20 log (Ei / Et) (1) SE: Shielding Effect (dB) Ei: Incident Electric Field Strength Et: Conduction Electric Field Strength As described above, the porous material manufactured by the manufacturing method of the present invention. The building material has both soundproofing and electromagnetic shielding properties. In addition, the porous construction material as a whole, and even the conductive layer alone, are (a) strong enough to withstand a little rough handling, (b) homogeneous and do not change for a long time.
Furthermore, since it is not necessary to use expensive materials such as gold and silver and the manufacturing process is not complicated, this porous building material is excellent in (c) cost.

[0029]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an explanatory diagram of a manufacturing process employed in Examples 1 to 3 described below. In FIG. 1, reference numeral 10 denotes a cellular concrete plate 10 as an inorganic material-based porous material of the present invention, which is commonly used in Examples 1 to 3 below. (Example 1) Example 1 is an example in which a brush coating method is employed.

First, the upper surface 12 of the cellular concrete plate 10
Then, an aqueous solution of tin chloride (18 wt%) was applied by brush coating to form a coating 14 of an aqueous solution of tin chloride having a thickness of about 5 μm (see FIG. 1A). This is housed in an electric furnace 16 and heated at about 180 to 200 ° C. for 15 to 60 minutes to thermally decompose the tin chloride to form a conductive layer 18 having a thickness of about 2 μm on the upper surface 12 of the cellular concrete plate 10. A porous building material 20 having a soundproof property and an electromagnetic wave shielding property was obtained. Example 2 Example 2 differs from Example 1 in that an aqueous solution of tin chloride was applied by a spray method, but other conditions were the same.

As shown in FIG. 1B, a tin chloride aqueous solution 24 was sprayed on the cellular concrete plate 10 using a spray nozzle 22 to form a tin chloride aqueous solution coating 14 having a thickness of about 5 μm. This was subjected to a heat treatment in the same manner as in Example 1 to obtain a porous building material 20 having a conductive layer 18 having a thickness of about 2 μm. (Embodiment 3) Embodiment 3 is the same as Embodiment 2 in that a spray method is used, but differs in that spraying is performed in an electric furnace 16.

First, the cellular concrete plate 10 is placed in an electric furnace 16.
And heated to about 200-220 ° C. On the upper surface 12 of the heated cellular concrete plate 10,
An ethanol solution (9 wt%) of tetrabutoxy tin 26 was sprayed from the spray nozzle 22a in two parts.
The amount of one application corresponds to an amount that makes the thickness of the conductive film about 1.0 μm. A thermal decomposition reaction was caused in parallel with the first and second sprays to obtain a porous building material 20 having a conductive layer 18 (final thickness of about 2 μm) formed by thermal decomposition of tetrabutoxy tin. Since the thermal decomposition is completed in about two to three seconds for one spraying, the time interval between the first and second spraying is set to a time corresponding thereto. This method is superior to Examples 1 and 2 in that the method does not require the movement of the cellular concrete plate 10 from the application of the thermally decomposable compound to the thermal decomposition and that the reaction time is extremely short.

FIG. 2 is a partially enlarged sectional view of the porous building material 20 obtained in Examples 1 to 3 above. The upper surface 1 of the cellular concrete plate 10 has
Even if 2 has irregular irregularities, the applied tin chloride or tetrabutoxy tin solution has no defect in the conductive layer 18 formed sufficiently in the pores 28.

FIG. 3 is an explanatory view for explaining the soundproofing property and the electromagnetic wave shielding property of the porous building material 20 obtained in the above Examples 1 to 3. When the electromagnetic waves 40 arrive at the porous building material 20, they are reflected and absorbed by the surface conductive layer 18 and rapidly attenuate, so that the electromagnetic waves 40a transmitted through the porous building material 20 are extremely weak.

The sound wave 50 arriving at the porous building material 20
Pass through the conductive layer 18 which is extremely thin as compared with the porous building material 20 with almost no influence. The sound wave 50 passing through the conductive layer 18 collides with the cellular concrete plate 10 constituting the porous building material 20. Part of the colliding sound wave 50 is emitted as a reflected wave 50a. On the other hand, the sound wave 50b that escapes the reflection further travels inside the cellular concrete plate 10. At this time, the porous building material 20 starts to cause reciprocating vibration and bending vibration, though the whole of the porous building material 20 is too small to be visually observed. Since the sound wave 50b travels in the cellular concrete plate 10 which is generating these vibrations, the sound wave 50b receives a transmission loss and is attenuated. Furthermore, since numerous pores 10a exist in the inside of the cellular concrete plate 10, sound incident on these pores 10a is repeatedly reflected in the pores 10a. As a result, ultimately, the vibration energy of the sound is changed to heat energy. As described above, since the energy of the sound wave 50b passing through the porous building material 20 is sufficiently attenuated, the porous building material 20 has excellent soundproofing performance.

FIG. 4 shows a modification of the porous building material 20. FIG. 4A shows an example in which the conductive layer 18 is formed on one surface of the cellular concrete plate 10 in the same manner as in Examples 1 to 3 above. FIG. This is an example in which No. 18 is formed. Fig. 4 (b)
When the conductive layers 18 and 18 are formed on both surfaces as described above, the electromagnetic wave shielding effect is further improved, and the electromagnetic wave shielding effect can be maintained even if a part of the cellular concrete plate 10 is missing.

FIG. 4C shows an example in which a cellular concrete plate 10b having an uneven surface is used. As described above, the present invention can be implemented regardless of the surface shape of the cellular concrete plate 10b. In addition, the said Example is only showing the preferable example which actualized this invention, and this invention is not limited to these Examples. For example, in the above-described embodiment, a flat porous building material was manufactured using a cellular concrete plate as an inorganic porous material, but the porous material is not limited to cellular concrete, and various types of materials such as ceramics can be used. Can be used. Further, the shape of the porous building material is not limited to a flat plate shape, but may be any shape such as a columnar shape, a hollow body shape, and an irregular shape.

[0038]

As described above, according to the present invention, according to the present invention, it has both soundproofing properties and electromagnetic wave shielding properties while being an integral material, and (a) it is strong enough to withstand a little rough handling; (B) It is possible to produce a porous building material which is homogeneous and does not deteriorate over a long period of time and (c) is excellent in cost.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a procedure for manufacturing a porous building material of an example.

FIG. 2 is a partially enlarged cross-sectional view of a porous building material of an example.

FIG. 3 is a schematic diagram for explaining an electromagnetic wave shielding effect and a soundproofing effect of the porous building material of the example.

FIG. 4 is an explanatory view of a modified example of the porous building material of the embodiment.

[Explanation of symbols]

10, 10b ... cellular concrete board, 10a ...
Pores, 18: conductive layer, 20: porous building material, 24
... Aqueous solution, 40, 40a ... Electromagnetic wave, 50, 50
a, 50b ... sound waves.

Claims (1)

(57) [Claims] 1. A method of applying a compound or a solution of the compound which thermally decomposes to form a conductive material on the surface of an inorganic material-based porous material, and thermally decomposes the applied compound to form a surface of the porous material. A method for producing a porous building material, comprising forming a conductive layer.