JPH108266A - Coated metal sheet with excellent condensation resistance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dew-condensation-resistant effect by forming a coating layer having a small contact angle of water on the surface of a metal plate and a low hydrophilicity with a coating film. To provide a coated metal sheet. SOLUTION: The coated metal plate excellent in dew condensation resistance characterized in that a coating layer having a contact angle of pure water at 20 ° C. of 30 ° or less is formed on the surface of the metal plate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a wall as a building material,
The present invention relates to a coated metal plate having excellent dew condensation resistance used as a member for an interior, a floor, a pillar, and the like.

[0002]

2. Description of the Related Art In general, metal plates have advantages such as excellent strength, workability, and light weight, and are inexpensive, and are widely used for roofs, walls, etc. by utilizing their characteristics. For example, as a metal plate, a galvanized steel plate, an aluminum-plated steel plate, a stainless steel plate, a titanium plate, an aluminum plate, and the like are used.

[0003]

As described above, as compared with other materials such as wood, it has excellent properties such as excellent strength, workability and light weight, and is inexpensive. Although they are used, these metal plates have a disadvantage that they easily condense. If the time of dew condensation is long, corrosion of this part is likely to progress, and the long-term permanent property is deteriorated. As a result, the life of the building is shortened, which is a problem. In addition, there is also a problem that mold and the like are generated in a portion where dew condensation is likely to occur and emit a strange odor. As countermeasures against this, various measures have been taken, such as designing the structure to allow the humidity that causes condensation to escape outside the house, and using a heat insulating material to prevent the formation of a dew condensation environment. However, there are problems such as a lack of design freedom and a high cost of a heat insulating material.

[0004]

Means for Solving the Problems In order to solve the above-mentioned problems, the present inventors have made intensive developments. As a result, a coating layer having a small contact angle of water and a very high hydrophilicity with water is formed on the surface of a metal plate. It has been found that the formation can exert the effect of dew condensation resistance. The gist of the present invention resides in a coated metal plate excellent in dew condensation resistance, characterized in that a coating layer having a contact angle of pure water at 20 ° C. of 30 ° or less is formed on the surface of the metal plate.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings. FIG. 1 is an explanatory diagram showing a contact angle of pure water on a metal plate surface according to the present invention. As shown in FIG. 1, when a coating layer 2 is formed on the surface of a metal plate 1 and a contact angle when pure water 3 adheres to the coating layer 2 is θ, the contact angle θ is 30 degrees. The following is assumed. The reason for setting the contact angle θ to 30 degrees or less is that even if water is condensed on the coating layer 2, the coating surface is excellent in the wettability and spreadability of water, so that the surface area of water increases and the non-condensing environment This is because the drying speed becomes faster. If the water condensed on the coating surface dries quickly, the time during which the surface is wet with water is shortened, and the progress of corrosion is suppressed.

In this case, the metal plate includes a steel plate, a plated steel plate, a stainless steel plate, a titanium plate, an aluminum plate and the like.
Before forming the coating layer, pretreatment may be performed. For example, degreasing, washing with water, washing with hot water, pickling, alkali treatment, chromate treatment, phosphate treatment and the like. By performing these pretreatments, the adhesion between the coating layer and the metal layer is improved,
Corrosion resistance is also improved. When forming a pretreatment layer, if the solubility of the pretreatment layer in water is large, the adhesion of the coating layer may deteriorate over time, so use a pretreatment with low solubility in water. Is desirable. Specifically, after forming the pretreatment layer, when the metal plate on which the pretreatment layer is formed is immersed in boiling water for 10 minutes, the weight of the dissolved component is 30% of the weight of the original pretreatment layer. It is desirable that: If necessary, a coating layer may be further provided between the pretreatment layer and the surface coating layer. For example, when it is necessary to further improve the corrosion resistance, when providing a coating layer having good corrosion resistance, when maintaining the hydrophilicity of the hydrophilic coating layer on the surface for a long time, when providing the same hydrophilic coating layer as the surface, etc. There is.

The coating to be formed may be formed by painting, or a coating layer formed in advance on a film may be attached. As a coating to be formed, there is a resin obtained by adding inorganic silica to a resin containing a hydroxyl group or an amino group. Examples of the resin containing a hydroxyl group include an acrylic resin, a polyvinyl alcohol resin, and an epoxy resin. Examples of the resin containing an amino group include an amide resin and an amino resin. The resins may be mixed or reacted at the time of resin synthesis to form a composite so that both the hydroxyl group and the amino group are contained in the resin. For example, acrylamide resin, methacrylamide resin, aminoacrylic resin, epoxy-amide resin, amino-epoxy resin and the like. When the hydroxyl equivalent and the amino group equivalent of the resin, or the functional group equivalent when considering a hydroxyl group and an amino group as a functional group, when the 3000 or less,
In particular, the water wettability is improved.

As the inorganic silica, colloidal silica, fumed silica and the like can be used. The mixing ratio of the resin and silica is not particularly limited, but if the amount of silica in the coating exceeds 50% based on the coating solid content, the coating becomes too hard,
It is not preferable because processability is deteriorated. The film thickness to be formed is not particularly limited, and may be appropriately selected in consideration of the contact angle of pure water and corrosion resistance. However, when the film thickness is 0.5 μm or less, the hydrophilicity is hardly long-lasting, and the corrosion resistance is slightly deteriorated. Further, those obtained by reacting an organic silane compound with the hydroxyl group-containing resin or the amino group-containing resin, or a resin having a hydroxyl group and an amino group-containing resin can also be used. Examples of the organic silane compound include monosilane, disilane, trisilane, and silane coupling agents such as vinyltrichlorosilane, vinyltriethoxysilane, and vinyltrimethoxysilane. The coating layer may be formed on both sides of the metal plate,
If it is known in advance that only one side needs to have dew condensation resistance, it may be formed on one side.

FIG. 2 is a graph showing the relationship between the contact angle of water and the dew point rating. As a test method, JIS-A151
Based on the condensation test method specified in 4, the metal plate on which the coating layer according to the present invention was cooled to 10 ° C. in an atmosphere of 50 ° C. and a relative humidity of 50% was exposed for 15 minutes, and the condensation on the metal plate surface was visually observed. did. The evaluation of the degree of condensation was performed according to the following rating. ：: no fogging, ○: fogging, Δ: generation of small water droplets, ×: generation of large water droplets or water flow As shown in this figure, the contact angle of water at 20 ° C. was 30.
When the temperature is lower than the degree, it is understood that the dew condensation score is good.

Further, the tested metal plate is placed in an atmosphere at a temperature of 20 ° C. and a relative humidity of 60% immediately after the test, and
Observation of the metal plate surface after 5 minutes showed that the metal plate on which the coating layer having a low contact angle was formed dries moisture quickly. This is presumably because the water spreads sufficiently on the surface of the coating, so that the surface area of the water is large and the water is easily dried. This tendency was particularly apparent in a metal plate having a contact angle of pure water at 20 ° C. of 30 ° or less. Further, the coating layer having a contact angle of pure water at 20 ° C. of 30 ° or less also has water absorption, and even if dew condensation occurs, it prevents the dew condensation water from dripping and easily forms dew condensation in rainy weather or at night. The dew condensation water is temporarily held in the environment, and the water can be quickly evaporated when the environment becomes non-condensing such as in fine weather or in the daytime.

[0011]

EXAMPLE A surface of a hot-dip galvanized steel sheet was subjected to electrolytic chromate treatment as a base treatment to form a chromate layer having low solubility in water (adhesion amount: 40 mg / m ² as Cr) on both surfaces of the metal plate. A paint containing 85 parts of an acrylic resin containing a hydroxyl group and having a hydroxyl equivalent of 1000 and 15 parts of inorganic colloidal silica was applied thereon by a roll coater,
Dry under the condition that the plate temperature becomes 150 ° C.
A μm coating layer was formed. This coating film was also formed on both sides of the metal plate. The contact angle of pure water at 20 ° C. on the surface of the metal plate on which the coating film was formed was 20 degrees. The dew condensation resistance of the obtained coated metal sheet was compared with a non-painted hot-dip galvanized steel sheet having only a primary rust-resistant chromate film formed thereon, according to JIS-A1514. The contact angle of pure water at 20 ° C. of the hot-dip galvanized steel sheet having only the chromate film formed thereon was 55 °. 50 pieces of both metal plates
After exposure to an atmosphere at 50 ° C. and a relative humidity of 50% for 15 minutes, dew condensation on the surface was observed.

As a result, in the galvanized steel sheet having the coating film layer formed thereon, the surface of the coating film was observed to be slightly wet with water, and the degree of fogging was slightly observed. On the other hand, in the hot-dip galvanized steel sheet having no coating layer, water droplets adhered to the surface. Clearly, the steel sheet having the coating film formed thereon according to the present invention was excellent in dew condensation. Immediately after this test, the temperature was 20 ° C.
When placed in an environment with a relative humidity of 60% and observed 15 minutes later, the steel sheet on which the coating film had been formed did not seem to have already been wetted by water and had been dried. In contrast, the surface of the steel sheet on which only the chromate treatment layer was formed was still wet with water. As described above, the metal plate according to the present invention is hardly dewed even in a dew condensation environment, and even if dew is formed, it has excellent wettability and spreadability, the surface area of water is large, and drying in a non-dew condensation environment is possible. Extremely fast. It was confirmed that it was effective in preventing dampness and ensuring comfort in the living environment.

[0013]

As described above, according to the present invention, 20 ° C.
Forming a coating layer with a contact angle of pure water of 30 degrees or less in, makes it possible to manufacture metal sheets with extremely excellent dew condensation resistance with high productivity, and to expand the use of metal sheets in the field of building materials. Can be measured.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a contact angle of pure water on a metal plate surface according to the present invention;

FIG. 2 is a diagram showing a relationship between a contact angle of water and a dew condensation score.

[Explanation of symbols]

 1 metal plate 2 coating layer 3 pure water

Claims (1)

[Claims] 1. A coated metal sheet having excellent dew condensation resistance, wherein a coating layer having a contact angle of pure water at 20 ° C. of 30 ° or less is formed on the surface of the metal sheet.