JPH05104060A - Formation of uneven pattern painting - Google Patents

Abstract

PURPOSE:To make coating thickness control of an uneven pattern painting, such as hammering condition, etc., easy at the time of powder painting of an uneven pattern forming paint, improve the painting efficiency, and obtain a painted body with painting appearance and rust-proofing property. CONSTITUTION:An undercoating 2 is formed on the surface of a coating object 1 made of a metal 1 and pretreated for coating and an uneven pattern forming paint is applied by powder painting to the undercoating to form an uneven pattern paint coating 3. The undercoating 2 has high adhesion strength to the uneven pattern paint coating 3 and by making its color same color tone of the recessed parts of the paint coating 3, even if pin holes are formed in the uneven pattern paint coating 3, the undercoating 2 is exposed and the excellent appearance and rust-proofing property are maintained.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an uneven pattern for improving the appearance and the quality of a coating when forming a hammer-like uneven pattern coating on the surface of a metal article by powder coating. The present invention relates to a method for forming a coating film.

[0002]

2. Description of the Related Art Conventionally, as a concavo-convex pattern forming coating material for forming a concavo-convex pattern coating film such as a hammer tone by powder coating, for example, a resin mixture having a different curing rate is used, and a concave portion of the coating film is formed by a resin having a fast curing rate. There is known a commercially available coating in which a convex portion of a coating film is formed by a resin having a slow curing rate. In the conventional method, an uneven pattern coating film is formed by subjecting the surface of a metal coated object to appropriate pretreatment such as degreasing and chemical conversion treatment, and then powder coating the above coating material.

[0003]

In general, the above-mentioned uneven pattern-forming coating composition cannot obtain an uneven pattern if the coating film thickness during powder coating is too thin, and it is necessary to have an appropriate film thickness for exhibiting the uneven pattern. The thickness of the coating film also varies depending on the shape of the object to be coated.

In the conventional method, the coating material for forming the uneven pattern is directly powder-coated on the object to be coated. Therefore, when the coating film of the uneven pattern is thin, pinholes are generated and the appearance of the film is deteriorated. There is a problem that the rust and corrosion easily occur from the hole portion and the coating quality is inferior. Further, if repainting is performed in order to correct the generated pinhole portion, the appearance of the coating film is deteriorated as a whole, which is not preferable. For this reason, in the conventional method, it is necessary to severely control the thickness of the coating film at the time of powder coating of the uneven pattern forming paint, and it is difficult to improve the coating efficiency.

It is an object of the present invention to provide a method for forming an uneven pattern coating film which solves the above conventional problems.

[0006]

In order to solve the above-mentioned problems, the method for forming a concavo-convex pattern coating film according to the present invention comprises a resin composition having different curing speeds or surface tensions on the surface of a pretreated metal coated object. When forming a concave-convex pattern coating film by powder-coating a concave-convex pattern forming paint consisting of, the surface of the object to be coated has adhesiveness with the concave-convex pattern coating film and has a color similar to the color of the concave portion of this coating film. The undercoat is formed beforehand on the coating film.

[0007]

According to the present invention, since the uneven coating film is formed on the undercoating film, the undercoating film of the pinhole portion is exposed even if a pinhole occurs in the uneven coating film,
The exposed undercoating film appears to be integrated with the recesses of the uneven coating film on the appearance and also serves as a rust preventive for the object to be coated.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 shows a coated body on which an uneven pattern coating film is formed by the method of the present invention, 1 is a metal article to be coated, 2 is an undercoat coating film,
3 is an uneven pattern coating film.

The metal-coated article 1 is made of an appropriate metal material such as aluminum die-cast, galvanized or hot-dip galvanized steel, and its shape is not particularly limited. Absent. First, the surface of the article to be coated 1 is roughened by sandblasting, shot blasting, desk sander, wire sander, etc., or degreasing and chemical conversion treatments, or by a combination of the above-mentioned roughening and degreasing and chemical conversion treatments. Pre-process. As the chemical conversion treatment, it is preferable to degrease the surface of the article to be coated 1 and wash it with water, and then form a phosphate coating having excellent corrosion resistance and adhesion.

Next, an undercoat coating film 2 is formed on the surface of the pretreated article 1. The undercoat coating film 2 has adhesion to the uneven coating film 3 serving as the top coat, and since the uneven coating film 3 is generally formed of a polyester-based or epoxy-based resin, a resin coating similar to this is used. To form. The color of the undercoat coating film 2 is similar to the color of the concave portions of the uneven coating film 3. Generally, when the uneven coating film 3 has a hammer tone,
Since the concave portions of the coating film 3 are black, the color of the undercoat coating film 2 is often black.

The undercoat coating film 2 may be formed by applying and coating a solvent-based paint, a primer, or a powder paint. The thickness of the undercoat coating film 2 is 15 to 50 μm.
Is preferred. The reason for this is that if it is 15 μm or less, pinholes are likely to occur and the anticorrosive power is reduced, and if it is 50 μm or more, problems such as foaming and cracking occur during baking of the coating film, and a good coating film cannot be obtained. ..

Next, the uneven coating film 3 is formed by powder-coating the undercoat coating film 2 with the uneven pattern forming coating material. As the uneven pattern forming paint, generally, a resin mixture having different curing rates is used, and a resin having a high curing rate forms concave portions of the coating film 3 and a resin having a slow curing rate forms convex portions of the coating film 3, respectively. Use powder paint from. As the concavo-convex pattern forming paint, resin-containing paints having different surface tensions may be used instead of the resin-containing paints having different curing rates. The uneven pattern forming paint is generally a polyester or epoxy resin paint, mixed with colored car if necessary, such as bronze, gold, silver, bronze hammer etc. by 1 coat / 1 bake The uneven pattern coating film 3 is formed.

The average coating thickness of the uneven coating film 3 is 40 to 15
0 μ is preferable. The reason for this is that if it is 40 μ or less, the uneven pattern cannot be formed well and the coating film is scraped off, and the rust preventive power is reduced, and if it is 150 μ or more, electrostatic repulsion occurs during electrostatic powder coating and the coating film thickness is unsatisfactory. This is because it becomes uniform and it is difficult to obtain an uneven pattern.

Example 1 A hot dip galvanized steel pipe was used as an object to be coated, and the surface of the steel pipe was pretreated by the steps of degreasing, washing with water, chemical conversion treatment, washing with water and washing with pure water. Electrostatic powder coating of Nippon Oil & Fat Co., Ltd. Konak 1600), 19
It is heated at 0 ° C for 20 minutes to form an undercoating film with a thickness of 50μ, and then a polyester resin uneven pattern forming paint (Nissin Powder Coat S Bumpy Powder manufactured by Takashi Kubo Paint Co., Ltd.) is electrostatically powder coated at 200 ° C. And heated for 20 minutes to form a bronze hammer-like uneven pattern coating film having an average thickness of 120 μm.

Example 2 A black solvent-based paint of epoxy resin (AR-BT100 manufactured by Kubo Taka Paint Co., Ltd.) was applied to the surface of a hot-dip galvanized steel pipe which had been pretreated in the same manner as in Example 1 and was heated at 160 ° C. 15
The coating was heated for a minute to form an undercoating film having a thickness of 20 μm, and the same hammer-like uneven pattern coating film as in Example 1 was formed thereon.

Example 3 A black primer of epoxy resin (FF primer manufactured by Takashi Kubo Paint Co., Ltd.) was applied to the surface of a hot-dip galvanized steel pipe pretreated in the same manner as in Example 1, and heated at 160 ° C. for 15 minutes. Then, an undercoat coating film having a thickness of 20 μm was formed, and a hammer-like uneven pattern coating film similar to that in Example 1 was formed thereon.

Comparative Example 1 On the surface of a hot-dip galvanized steel pipe which had been pretreated in the same manner as in Example 1, the same undercoating film as in Example 1 was directly formed without forming an undercoating film.

Comparative Example 2 A white primer of epoxy resin (FF primer manufactured by Takashi Kubo Paint Co., Ltd.) was applied to the surface of a hot-dip galvanized steel pipe which had been pretreated in the same manner as in Example 1, and heated at 160 ° C. for 15 minutes. Then, an undercoat coating film having a thickness of 20 μm was formed, and a hammer-like uneven pattern coating film similar to that in Example 1 was formed thereon.

Regarding the coated bodies obtained in Examples 1 to 3 and Comparative Examples 1 and 2, the coating appearance, the presence or absence of pinholes, and the salt spray test (500 hours based on JIS-K-5400-9-1). The results are shown below.

Paint appearance Pinhole Salt spray test Example 1 ○ None ○ Example 2 ○ None ○ Example 3 ○ None ○ Comparative Example 1 × ~ ○ Yes × Comparative Example 2 × ~ ○ None ○

In Examples 1 to 3, there was a portion where pinholes were generated in the uneven coating film, but in this portion the undercoat coating film was exposed and a concave portion of the uneven coating film was formed, and the coating appearance was The coated body was kept in a good condition uniformly, and as a whole, a coated body having a good rust preventive property without pinholes was obtained. On the other hand, in Comparative Example 1, pinholes were formed in the uneven coating film, the surface of the steel pipe in the pinhole portion was exposed, and the coating appearance was not in a uniform and good state, and the corrosion resistance was also poor. I couldn't get it. In Comparative Example 2, the undercoating film of the pinhole portion generated in the uneven coating film was exposed, and this undercoating film gave a feeling of strangeness with the uneven coating film, and the coating appearance was not uniformly good.

[0022]

As described in detail above, the method for forming a corrugated pattern coating film of the present invention has the adhesiveness with the corrugated pattern coating film on the surface of the object to be coated and the color of the concave portion of this coating film is of a similar color. Since the coating film is formed as an undercoat, even if pinholes occur in the uneven coating film during powder coating, the undercoat film on the pinhole is exposed, and the undercoat film is integrated with the concave portions of the uneven coating film. It can be seen as, and the appearance of the coating can be made uniform and good, and pinholes can be prevented as a whole to improve rust prevention. Moreover, it becomes easy to control the thickness of the coating film during powder coating of the coating film for forming the uneven pattern, which improves the coating efficiency.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of a coated body on which an uneven pattern coating film is formed by the method of the present invention.

[Explanation of symbols]

 1 Metal coating 2 Undercoat 3 Uneven pattern coating

Claims (1)

[Claims] 1. A surface of a metal article to be pretreated,
When forming an uneven pattern coating film by powder-coating an uneven pattern forming paint composed of a resin mixture having different curing speeds or surface tensions, this coating film has adhesion to the surface of the object to be coated, A method for forming a concavo-convex coating film in which a coating film having a color similar to the color of the concave portions of the film is pre-coated.