JPH0662891B2 - Coating composition and coating method - Google Patents

Description

The present invention relates to a coating composition and a coating method used for cellular concrete, concrete, mortar, and other cement-based inorganic building materials.

[Conventional technology]

In general, inorganic building materials such as concrete have excellent characteristics in strength and fire resistance. However, this material reacts with carbon dioxide in the air and is chemically changing every moment.
For example, in the case of reinforced concrete, the reinforcement inside the concrete is protected by the alkalinity of the cement hydrate, but if the hydrate reacts with carbon dioxide and loses alkalinity, the reinforcement is at risk of corrosion. To be done. Further, this carbonation causes a dimensional change and a strength change of the material, and may cause cracking. Therefore, it is desirable to prevent such carbonation, but as an effective method, it is conceivable to coat the surface of the building material with a paint, film or the like having low carbon dioxide gas permeability. At this time, the concentration of carbon dioxide gas becomes higher on the indoor side than on the outdoor side due to exhalation, heating, cooking, etc., so that it is necessary to particularly consider the interior material.

On the other hand, it is desirable that the interior material be water vapor permeable. In the winter and rainy season, the relative humidity in the room is high, and the surface temperature of the inner wall is lower than the indoor air temperature, depending on the heat insulation of the wall. Therefore, when the wall surface is below the dew point, dew condensation occurs, which is unfavorable for hygiene, durability and aesthetics. At this time, if the interior material is water vapor permeable, it does not interfere with the moisture absorption and desorption properties of the building material. Therefore, when the humidity is high, water vapor moves into the wall, and when the humidity is low, water is released, so that dew condensation is less likely to occur.

Therefore, it is desirable that the interior material of the inorganic building material be permeable to carbon dioxide but not water vapor.

[Problems to be solved by the invention]

However, it is the current situation that interior materials with a high resistance to permeation of carbon dioxide also have high resistance to moisture permeation, and those with low resistance to permeation of carbon dioxide have a low resistance to permeation of carbon dioxide. there were. Problems like this
The same applies not only to cement-based inorganic building materials, but also to coating of materials that dislike carbonation.

[Object of the Invention]

An object of the present invention is to provide a coating composition and a coating method which do not prevent the water vapor permeability of inorganic building materials and other materials, and in which carbonation by permeation of carbon dioxide gas is not a problem.

[Means for solving problems]

The coating composition of the present invention has been solved by making the moisture permeability and the carbon dioxide gas impermeability, which are basically opposite properties, to be specific compositions.

That is, the coating composition of the present invention contains a water-dispersible coating resin and diatomaceous earth, the pigment volume concentration is 30 to 50%,
A coating composition in which the diatomaceous earth content is 50 to 150 parts by weight with respect to 100 parts by weight of the resin solid content.

Further, the coating method of the present invention is basically a reciprocal property of moisture permeability and carbon dioxide gas impermeable, using a specific coating composition, and the water vapor permeability and carbon dioxide gas permeation of the coating film. It was confirmed by experiments that by setting the degree within a certain range, the problems of early-stage dew condensation and carbonation do not substantially occur.

That is, the coating method of the present invention uses a coating composition according to the present invention containing a resin for water-dispersible coating material and diatomaceous earth, and the water vapor permeability of the coating film is 200 g / m ² · 24 hr or more, and carbonic acid. It is a coating method with a gas permeability of 200g / m ² · 24hr or less.

Examples of the water-dispersible coating resin used in the coating composition of the present invention include acrylics, acrylic-styrenes, vinyl acetates, vinyl acetate-vinyl versatate, ethylene vinyl acetate, acrylonitrile, vinyl chloride, One or a combination of two or more selected from natural or synthetic rubbers can be used.

In addition, as the diatomaceous earth, a highly effective effect can be obtained by using a calcined porous material.

Further, in the present invention, as the inorganic building material to which the water-dispersible coating composition is applied, if the material itself has a large moisture absorption / desorption property like cellular concrete, a greater effect can be obtained.

In order to produce the water-dispersible coating composition of the present invention, in addition to the resin for water-dispersible coating and diatomaceous earth, an additive such as a dispersant, a defoaming agent, an antiseptic, a thickener, a film-thickening aid, a pigment. Volume concentration (PV
C) An adjusting pigment and the like are appropriately added, and, if necessary, a color pigment for obtaining a desired color tone is dispersed by an ordinary paint disperser to produce the pigment.

This water-dispersible coating composition is applied to an inorganic building material or the like by at least one method selected from spray coating, roller coating and brush coating. At this time, if the coating amount is small, there is a dew condensation preventing effect, but the carbonation preventing effect may be insufficient, and if the coating amount is large, the carbonation preventing effect is satisfactory, but there is a risk of dew condensation. . Therefore, an appropriate amount of coating depends on the composition of the water-dispersible coating composition, but is 300 to 100.
It is preferably in the range of 0 g / m ² .

The coating method of the present invention can be applied not only to aerated concrete, concrete, mortar, and other cement-based inorganic building materials, but also to other materials that do not like carbonation.

〔Example〕

 Hereinafter, examples of the present invention will be described together with comparative examples.

Example 1 A paint having a diatomaceous earth content of 130 parts by weight per 100 parts by weight of a pigment volume concentration (PVC) of 40% using titanium dioxide and diatomaceous earth as a pigment, using a vinyl acetate water-dispersible resin as a binder was produced. .

As a comparative example, diatomaceous earth was changed to calcium carbonate, clay (clay), and mica (mica) to produce the same PVC paint.

The parts by weight of each formulation is shown in Table-1.

Brush each of the paints produced on the filter paper to 300 g / m ² to prepare test pieces, and measure the water vapor permeability of these test pieces according to JIS Z.
It was measured according to 0208. Further, the test sample prepared in the same manner was exposed in an atmosphere having a carbon dioxide concentration of 10%, a temperature of 20 ° C. and a relative humidity of 60%, and the carbon dioxide permeability was measured. Furthermore, each paint was applied to cellular concrete at a rate of 300 g / m ² , and the presence or absence of dew condensation when the surface was kept at a dew point temperature or lower was visually determined.

The measured results are shown in Table-2.

As described above, the carbon dioxide gas permeability is not so different among the four types, but the water vapor permeability of the diatomaceous earth pigment is significantly higher than that of the other pigments, and no dew condensation occurs.

Example 2 A paint having an acrylic styrene-based water-dispersible resin as a binder, titanium dioxide, diatomaceous earth, and calcium carbonate as pigments with a pigment volume concentration (PVC) of 50% and a resin solid content of 100 parts by weight and a diatomaceous earth content of 100 parts by weight. Manufactured.

As a comparative example, the same PVC was used, and coatings having diatomaceous earth contents of 30 parts by weight (Comparative Example 4) and 200 parts by weight (Comparative Example 5) were produced.

The parts by weight of each formulation is shown in Table-3.

Table 4 shows the results obtained by testing the produced coating materials in the same manner as in Example 1.

As shown in the table above, even with the same PVC, the diatomaceous earth content is 1 resin solids.
The amount of 100 parts by weight relative to 00 parts by weight shows high water vapor transmission rate even though the carbon dioxide gas permeability is low, and no dew condensation is observed. The diatomaceous earth content of 30 parts by weight hardly permeated carbon dioxide, but the moisture permeability was low, and dew condensation occurred. In addition, the water content and the carbon dioxide permeability of the diatomaceous earth content of 200 parts by weight are very high.

From this example and other basic experiments, resin solids of 100
The mixing ratio of diatomaceous earth with respect to parts by weight is preferably 50 to 150 parts by weight, more preferably 70 to 130 parts by weight.

〔The invention's effect〕

According to the coating composition of the present invention, there is an effect that the moisture permeability and the carbon dioxide gas impermeability are excellent.

Further, according to the coating method of the present invention, it is possible to prevent dew condensation on the material to be coated and also to prevent carbonation, which is a substantial problem.

Regarding the present invention, a so-called Patrice search was conducted using IPC as "C09D 5/00" and the keyword as "water dispersible, diatomaceous earth", and found that "dye composition and coating method" as in the present invention was found. In other words, the novelty of the present invention in the field has been revealed.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Toru Saito, Toru Saito, 1828 Nishibori, Urawa-shi, Saitama Misawa Ceramic Chemical Co., Ltd. References JP-A-60-210675 (JP, A)

Claims (3)

[Claims] 1. A coating composition comprising a water-dispersible coating resin and diatomaceous earth, having a pigment volume concentration of 30 to 50%, and a diatomaceous earth content of 50 to 150 parts by weight with respect to 100 parts by weight of a resin solid content. 2. A coating composition comprising a water-dispersible coating resin and diatomaceous earth, having a pigment volume concentration of 30 to 50% and a diatomaceous earth content of 50 to 150 parts by weight with respect to 100 parts by weight of resin solids. Water vapor permeability of the coating film is 200g / m ² · 24 when used
A coating method that is more than hr and has a carbon dioxide gas permeability of 200 g / m ² · 24 hr or less. 3. The coating method according to claim 2, wherein the coating amount of the coating composition is in the range of 300 to 1000 g / m ² .