JP2001206789A - Method for coating inorganic board and its coated structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for coating an inorganic board by which the blocking caused when the inorganic boards having ruggednesses on their surfaces are coated and then loaded is prevented at a low cost without falling a productivity. SOLUTION: The whole surface of an inorganic board having ruggednesses on the surface is coated with a first paint having 30-60 deg.C glass transition point, and them the protrusions on the surface are coated with a second paint having 60-100 deg.C glass transition point in <=20 μm thickness.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for coating an inorganic plate and a coated structure thereof. More specifically, the invention of this application relates to a method of coating an inorganic plate and a coating configuration thereof, which can prevent blocking caused when an inorganic plate having irregularities on the surface is loaded after being coated, without lowering productivity, and at low cost. It is about the body.

[0002]

2. Description of the Related Art Conventionally, various inorganic boards such as cement boards have been used as exterior materials such as exterior wall materials and roof materials of buildings. Inorganic plates are widely used because they have the advantages of nonflammability, ease of construction, versatile surface makeup, and low cost. Are provided with a wide variety of designs. In recent years, in particular, in order to provide a high-grade appearance, the surface is provided with deep irregularities and a coating is applied on the surface.

[0003] In general, this inorganic plate is formed by coating a raw material slurry composed of cement, aggregate, reinforcing material and the like, and subjecting the substrate to a process such as molding, curing, and drying. It is formed by applying a cosmetic finish.

[0004]

However, when the inorganic plate having the above-mentioned deep unevenness on the surface is loaded after painting, the loading surface comes into contact only with the projection, so that the load is applied only to the projection on the surface of the base material. Are concentrated, and blocking in which the coating film of the protruding portion adheres to the substrate or the like in contact with the film is likely to occur. When the blocking of the coating film occurs, there is a problem that when the substrate is moved from the loaded state, the coating film is subjected to physical force, peels off, and causes poor appearance as a product.

This problem occurs notably when the heat applied to the substrate for drying and baking the paint during the coating process is not sufficiently cooled and the temperature of the substrate is higher than the glass transition point of the paint. I do. For this reason, measures such as natural or forced cooling to around room temperature after the completion of the coating process can be considered.

However, natural cooling to near room temperature requires a long period of time, and a reduction in productivity is considered a problem. Further, the forced cooling can cool the substrate in a short time, but has a problem that it requires a very large amount of energy.

[0007] The invention of this application has been made in view of the above-mentioned circumstances, and it is possible to reduce blocking that occurs when an inorganic plate having irregularities on the surface is loaded after coating without lowering the productivity and at a low cost. It is an object of the present invention to provide a method for coating an inorganic plate which can be prevented in a short time and a coated structure thereof.

[0008]

Means for Solving the Problems According to the invention of the present application, a first paint having a glass transition point of 30 to 60 ° C. is applied over the entire surface of an inorganic plate having an uneven surface. A method for coating an inorganic plate (claim 1), comprising applying a second coating having a glass transition point of 60 to 100 ° C. to a thickness of 20 μm or less on the surface projections. .

Further, the invention of the present application is directed to a method in which a glass transition point of 30 to 60 ° C. is applied to the entire surface of an inorganic plate having an uneven surface.
The method for coating an inorganic plate is characterized in that an organic coating is applied on the surface of the substrate, and then an inorganic coating is applied to the surface projections with a thickness of 20 μm or less.

Further, the invention of this application also provides an inorganic plate coating structure (claim 3) which is coated by the above-mentioned method for coating an inorganic plate.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The invention of this application has the features as described above, and embodiments thereof will be described below.

First, in the method for coating an inorganic plate provided by the first invention of this application, a first paint having a glass transition point of 30 to 60 ° C. is applied to the entire surface of the inorganic plate having irregularities on the surface. Then, the glass transition point is 60 to
A second paint at 100 ° C. is applied with a thickness of 20 μm or less.

The composition of the inorganic plate is not limited.
What is widely and generally used as a base material or the like of the exterior material is targeted. For example, a cement plate containing cement, aggregate, and reinforcing fibers as main components is exemplified. Also, regarding the unevenness of the surface of the inorganic plate, the shape and the forming method are not limited. For example, in order to provide various uneven patterns such as a groove shape, a wrinkle shape, press molding, injection molding, or the like may be used. it can.

A first paint as a cosmetic is applied to the entire surface of such an inorganic plate. The first paint is not particularly limited except that the glass transition point is 30 to 60 ° C, and for example, various organic paints or inorganic paints can be used. Specifically, a commonly used paint such as an acrylic emulsion paint having a glass transition point within the above range can be used. The paint may be of one kind or a plurality of kinds, and there is no particular limitation on the coating method.
For example, a glass transition point of 30 to 60 ° C. and a plurality of types of paints having different colors may be simultaneously applied by using a spray or the like, or a paint having a glass transition point of 30 to 60 ° C. In addition, glass transition points with different textures are 3
Overcoating with a paint at 0 to 60 ° C. can be applied. The first paint has a glass transition point of 30 ° C.
When a paint having a glass transition point of less than 60 ° C. is used, drying tends to be poor, and the application of the second paint is adversely affected.

Next, a second coating material having a glass transition point of 60 to 100 ° C. is applied to the surface projections of the inorganic plate at a thickness of 20 μm or less. The second paint has a glass transition point of 6
Those at 0-100 ° C. are used, which is important for the method of the invention. That is, when the glass transition point of the second paint is lower than 60 ° C., if the cooling after the heat treatment is not sufficient, the base material temperature may be higher than the glass transition point of the paint, and blocking occurs. The possibility arises. Further, when the glass transition point exceeds 100 ° C., a very large amount of energy is required for drying and curing the coating film, and the stress due to the curing shrinkage of the coating film and the shrinkage of the base material after production is not easily reduced. In addition, there is a problem that cracks are easily generated. In addition, the composition of the second paint is not particularly limited.
An acrylic emulsion paint having a glass transition point within the above range is exemplified. This coating material may be, for example, an enamel containing a color pigment, or may be clear. In the former case, it is possible to obtain a complicated surface design in which only the protrusions are different in color.

The coating method may be applied only to the surface projections, and there is no particular limitation. The surface protrusion includes a portion that comes into contact with a base material or the like during loading and the periphery thereof. Even if it is a projecting portion, a portion that does not come into contact with a substrate or the like at the time of loading does not have to be coated with paint. The coating on the surface projections, for example,
This is realized by a method using a roll or the like. By coating on the surface protrusions, even for a coating film having a relatively high glass transition point within the above range, the stress during curing shrinkage is easily released,
Cracks can be prevented from occurring. Further, by painting only the portions that come into contact during loading, the effect of economically preventing blocking can be obtained without painting the entire surface, which is advantageous in terms of cost.

It is important that the film thickness be 20 μm or less from the viewpoint of promoting the drying and curing of the coating film and reducing the stress during drying shrinkage. When the film thickness exceeds 20 μm, a large energy is required to dry and cure the coating film, and the stress at the time of curing shrinkage of the coating film increases,
There is a problem that cracks easily occur.

After the application of the second paint, drying and cooling to about 60 ° C. or lower may be performed as necessary. This makes it possible to inexpensively prevent blocking that occurs when an inorganic cement plate having irregularities on the surface is loaded after coating, without reducing productivity.

The method for coating an inorganic plate provided by the second invention of this application uses an organic paint as the first paint and an inorganic paint as the second paint in the method of the first invention. The feature is that it does.

The first paint has a glass transition point of 30 to 60.
There is no particular limitation except for the organic coating at a temperature of ° C. As the inorganic paint as the second paint, for example, the general formula R _n Si
X _4-n , more specifically, (C ₂ H ₅ ) ₃ Si
Examples include those mainly containing a silicon alkoxide such as (OC ₂ H ₅ ) and containing a curing catalyst. This inorganic paint may be an enamel containing a color pigment or may be clear, and may further contain additives such as a filler, a pigment, a dispersant, and a photocatalyst.

The silicon alkoxide has an average composition formula of R _a S
It may be represented as i (OH) _b O _{(4-ab) / 2} . Alternatively, it may be a mixture with the former. In the latter, in the formula, _Ra represents the same or different substituted or unsubstituted monovalent hydrocarbon group having 1 to 8 carbon atoms;
And b are numbers satisfying the relationship of 0.2 ≦ a ≦ 2, 0.0001 ≦ b ≦ 3, and a + b <4. In particular,
(C ₂ H ₅ ) Si (OH) O and the like are exemplified.

As the curing catalyst, those generally used can be used, and examples thereof include a metal salt of octenoic acid, a metal salt of naphthenic acid, and metal butoxide. Since the inorganic paint as described above does not soften even at a high temperature, by coating this paint on the protrusion, the surface protrusion serving as a contact portion at the time of loading has a high hardness, and effectively prevents blocking during loading. be able to.

Thus, the same effect as in the first invention can be obtained. Further, the inorganic plate coating structure of the invention of this application is coated by the above-described method for coating an inorganic plate. Therefore, even when deep irregularities are provided on the surface for the purpose of giving a sense of quality, blocking of the coating film during loading does not occur.

That is, an inorganic plate-coated structure can be provided at low cost without deteriorating the appearance or reducing the productivity. Examples will be shown below, and the embodiments of the present invention will be described in more detail.

[0025]

EXAMPLES Example 1 A water-based acrylic emulsion paint having a glass transition point of 45 ° C. was applied as a first paint to an inorganic cement plate having a thickness of 12 mm and having irregularities having a maximum depth of 4 mm on the surface. Was spray-coated so as to be 40 μm.

A water-based acrylic emulsion paint having a glass transition point of 60 ° C. was roll-coated on the protrusions of the coated plate as a second paint so that the film thickness became 10 μm.
The coated plate is baked for 1 minute in an oven at 150 ° C., and cooled until the temperature of the coated plate reaches 50 ° C.
The coated plates subjected to the same treatment were stacked so that the front surface and the back surface were in contact with each other, and a load of 3 kg / cm ² was applied in the loading direction for 6 hours to reproduce the loaded state of the coated plates in the actual process. (Example 2) The glass transition point of the second paint in Example 1 was set to 100 ° C. (Embodiment 3) The film thickness of the second paint in
It was set to 0 μm. (Comparative Example 1) The glass transition point of the second paint in Example 1 was set to 50 ° C. (Comparative Example 2) The glass transition point of the second paint in Example 1 was set to 120 ° C. (Comparative Example 3) ) The film thickness of the second paint in Example 1 was 3
It was set to 0 μm. (Comparative Example 4) The second paint in Example 1 was not applied. (Comparative Example 5) The glass transition point of the first paint in Example 1 was set to 70 ° C.

The coated plates obtained in Examples 1 to 3 and Comparative Examples 1 to 5 were observed with a loupe to observe the blocking state, the dryness to the touch, and the presence or absence of cracks in the coating film at the initial stage and after the hot air drying test. And evaluated. In the warm air drying test, the obtained coated plate was immersed in warm water at 60 ° C. for 8 hours, and then air-dried for 16 hours, for 10 cycles.

The coating conditions of Examples 1 to 3 and Comparative Examples 1 to 5 and various evaluation results are shown in Table 1.

[0029]

[Table 1]

With respect to the coated plates obtained in Examples 1 to 3,
No blocking occurred, and both the dryness to the touch and the crack resistance of the coating film were good. In the coated plate obtained in Comparative Example 1, blocking occurred because the glass transition point of the second coating material was too low at 50 ° C.

In the coated plate obtained in Comparative Example 2, since the glass transition point of the second coating material was too high at 120 ° C., the coating film was insufficiently dried and the touch dryness was deteriorated. Further, the stress during the curing shrinkage and the stress during the substrate shrinkage were not alleviated, so that the crack resistance was poor.

In the coated plate obtained in Comparative Example 3, since the thickness of the second coating material was too thick as 30 μm, drying of the coating film was insufficient and touch dryness was slightly deteriorated. In addition, since the stress during curing shrinkage was excessive, crack resistance was poor.

Since the coated plate obtained in Comparative Example 4 was not coated with the second coating material, it came into contact with the first coating material having a low glass transition point, and blocking occurred. Since the coated plate obtained in Comparative Example 5 was coated with the second coating material having a high glass transition point over the entire surface, the coating film was not sufficiently dried.
Dryness to the touch deteriorated. In addition, since the stress during curing shrinkage was excessive, crack resistance was poor. (Example 4) A water-based acrylic emulsion paint having a glass transition point of 45 ° C as an organic paint was applied to an inorganic cement plate having a thickness of 12 mm and having irregularities having a maximum depth of 4 mm on the surface.
The entire surface was coated with a spray so that the film thickness became 40 μm.

On the protruding portion of the painted plate, as an inorganic paint,
A: (C ₂ H ₅ ) ₃ Si (OC ₂ H ₅ ) and B: (C
_A silicon alkoxide coating material consisting of 50:50 (weight ratio) of ₂ H ₅ ) Si (OH) O was
m was applied with a roll.

The coated plate is baked in an oven at 150 ° C. for 1 minute, cooled until the temperature of the coated plate reaches 50 ° C., and the coated plates subjected to the same treatment are brought into contact with each other. 3kg / cm ² in the loading direction
Was applied for 6 hours to reproduce the loaded state of the coated plate in the actual process. (Example 5) The film thickness of the inorganic paint in Example 4 was set to 20
μm. (Comparative Example 6) The thickness of the inorganic paint in Example 4 was set to 30
μm. (Comparative Example 7) The inorganic paint in Example 4 was not applied. (Comparative Example 8) The inorganic paint in Example 4 was applied to the entire surface by spraying.

The coated plates obtained in Examples 4 and 5 and Comparative Examples 6 to 8 were observed with a loupe to observe the blocking state, the dryness to the touch, and the presence of cracks in the coating film at the initial stage and after the hot-air drying test. And evaluated. In the hot air drying test, the obtained coated plate was immersed in hot water at 60 ° C. for 8 hours, and then air-dried for 16 hours, for 10 cycles.

Table 2 shows the coating conditions of Examples 4 and 5 and Comparative Examples 6 to 8 and various evaluation results.

[0038]

[Table 2]

With respect to the coated plates obtained in Examples 4 and 5, no blocking occurred, and the dryness to the touch and crack resistance of the coating film were good. In the coated plate obtained in Comparative Example 6, the thickness of the inorganic coating was too thick as 30 μm, so the drying of the coating was insufficient, and the dryness to the touch of the coating was slightly deteriorated. In addition, since the stress during curing shrinkage was excessive, crack resistance was poor.

Since the coated plate obtained in Comparative Example 7 was not coated with an inorganic coating, it came into contact with an organic coating having a low glass transition point, and blocking occurred. In the coated plate obtained in Comparative Example 8, since the inorganic coating was applied on the entire surface, drying of the coating film was insufficient, and the dryness to the touch of the coating film was deteriorated. Also, since the stress during curing shrinkage was excessive,
Crack resistance was poor.

Of course, the present invention is not limited to the above-described example, and it goes without saying that various aspects of the details are possible.

[0042]

As described in detail above, the present invention provides
Blocking that occurs when an inorganic cement plate having irregularities on the surface is loaded after painting can be prevented at low cost without lowering productivity.

Claims (3)

[Claims] 1. A first paint having a glass transition point of 30 to 60 ° C. is applied to the entire surface of an inorganic plate having irregularities on the surface, and then a glass transition point of 60 to 100 is applied to the surface projections.
A method for coating an inorganic plate, comprising coating a second coating material at a temperature of 20 ° C. with a thickness of 20 μm or less. 2. An organic coating having a glass transition point of 30 to 60 ° C. is coated on the entire surface of an inorganic plate having irregularities on the surface, and then the inorganic coating is coated on the surface projections with a thickness of 20 μm or less. Characteristic coating method of inorganic plate. 3. A coating composition for an inorganic plate, which is coated by the method according to claim 1 or 2.