JPS5849469A - Painting method for powder paint - Google Patents

Abstract

PURPOSE:To obtain paint films having good moldability by coating a primer of a pale color or a dark color of the same system as that of a dark color and heating and curing the primer according to need then finishing the same to 20- 50mu film thickness with the dark color of powder paint. CONSTITUTION:In the stage of finishing a substrate to a dark color by powder paint (e.g., polyester powder paint), a primer of a pale color or a dark color of the same system as that of said dark color (e.g., a polyester primer of solvent type) is coated and after the primer is heated and cured according to need, the same is finished to 20-50mu film thickness with the dark paint color of the powder paint. As a result, the powder paint is finished to the paint film of 20- 50mu thickness having good moldability and hiding power in the case of the paint film of the dark color as well.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for coating a highly processed metal plate, and more specifically to a method for coating a highly processed metal plate with a dark powder coating.

Recently, the application of painted metal sheet O as an OIk casting finishing system has begun to expand in the home appliance industry and the steel industry.

Painted metal plates are typified by pre-coated metal plates such as colored grave lead iron plates, and after coating zinc plates and other metal plates in advance with paint, any 01! Process it into a shape and use it for the final purpose 4
It is widely used as a construction material for things such as Node-sho, Shuseki, sightings, shutters, and shutters, and is also used for metal products such as home appliances. This kind of pre-coated gold plate has the advantage of streamlining the process of painting and ensuring uniform quality compared to the method of first forming a metal plate and applying paint to a complicated cedar-like object. It is thought that its use will continue to expand in the future as it has advantages such as reduced paint consumption and reduced paint consumption.

After the paint film is formed, it is molded into a shape suitable for the above-mentioned purpose, so the paint film is processed by bending, roll forming, embossing press, drawing, etc. It is required to maintain sufficient elongation and adhesion to metal surfaces to withstand processing. On the other hand, in the molded product, performance suitable for each end use is required, for example, high weather resistance and corrosion resistance of degree #i including processed sections are required for the Kenmulberry exterior material.
The application of painted metal sheets has begun to expand in the home appliance industry, steel furniture industry, etc., where electric appliances such as refrigerators require scratch resistance and stain resistance. One such reform method is to reduce the amount of exhaust solvents, alleviate health and safety issues and work environment problems caused by exhaust solvents, and take measures to prevent pollution. )(P
CM) is being considered. The features of this system are (1) The finished appearance is wavy and has a thick film.
(2) It is possible to paint cut surfaces and has a corrosion-resistant effect. (3) *It is easy to make the thickness distribution uniform, and the coating efficiency is high. (4) It does not take up much space to store and transport painted flat plates. (5) It is easy to automate painting and the maintenance around the painting booth is reduced.

However, in order to expand the scope of application of PCM (pre-coat method) using powder coatings, it was necessary to solve the following problems. That is, +1) The post-addition system by object paint is, for example, 20
A coating thickness of ~50 μm is necessary to ensure hiding power and coating performance, but on the other hand, thicker coatings are not preferred because moldability is poor.

(2) In the case of dark colored paint films such as yellow, red, and blue, the concealing film thickness is 50μ or more, so it cannot be put into practical use considering the above-mentioned moldability.

Therefore, the present invention eliminates the melting point of the prior art, and provides a 20 to 50 micron film with good moldability even in the case of dark colored coatings.
The purpose of the present invention is to provide a coating method suitable for a post-addition system using a powder coating capable of finishing a thick coating film with concealing power.

In the powder coating method according to the present invention, when finishing the object to be coated in a dark color with the powder coating, a light color or a dark color ply i- of the same type as the above-mentioned dark color is applied, and then, as necessary, Accordingly, there is provided a method for coating a metal plate for high processing, which is characterized in that, after heating and curing, the coating is finished with a deep color of powder coating to a film thickness of 20 to 50 μm.

As mentioned above, attempts have been made to use painted metal plates for flat plate cutting systems;
There were problems such as the finished appearance was too flat and there was no thick film, and the base material was exposed on the end face due to punching and cutting, which caused concerns about rusting. Furthermore, bending workability is an essential requirement for pcMi & films made of powder coatings, and coating film thickness is one of the items to be controlled.

Since the thickness of this coating film is determined by the thickness of the concealing film depending on the hue, there are limits to the use of powder coatings to create PCM. In addition, the relationship between hiding film thickness and molding processability was tested for Nitzpe Precoat 300 light colored and dark colored (powder coating for PCM whose main component is polyester resin, manufactured by Nippon Paint Co., Ltd.) as an example. The results are as follows.

Traditionally, powder coatings were applied after assembling refrigerators, washing machines, etc. into box shapes, which resulted in a layer with a film thickness distribution.Furthermore, since recovered powder coatings were recycled and used, the problem of waste defects occurred. Moreover, the task of changing colors was also very difficult. On the other hand, with the flat plate coating method, it is possible to achieve a coating efficiency of 90% or more, which is good without using TB and IA powder coatings. If collection is not carried out further, there will be no problem of dust defects, and the color change work will become a hassle. In particular, it is easy to make the film thickness distribution uniform.
Paint usage is reduced. However, top 1! As shown in Figure 2, if you want to obtain a darkly colored coating film, make the film thinner (20 to 50
There was a basic defect in which the substrate could not be concealed due to the thickness (μ thickness), and it was difficult to put it into practical use.

However, according to the present invention, as described above, when finishing a coated object in a dark color using a powder coating, a light color or a dark color ply i- of the same type as the dark color is applied, and then,
If necessary, heat and harden the wood and finish with a dark colored powder coating to a film thickness of 20 to 50 degrees. steel plates are painted.

In addition, the "-light color" and "iii color" used in this QI1g+ book are the Munsell color cloth OR yarn (red) (1st and 1) shown on the wrinkled 1st page, and the Y series (yellow). (
Each drawing 1(
In each drawing, area A shows a light color, and area B shows a dark color.

Light coloring and #coloring change from light color to dark color as the layer color pigment increases, so it is not necessarily possible to distinguish them from each other as shown in the figure, but for convenience, they are illustrated using lines due to the concealing effect of the undercoat and topcoat. did. About intermediate colors: 1 red, blue,
An analogy can be drawn from the mixture of Hérault.

As the Z1 primer used in the present invention, any conventionally known primer such as solvent-based polyester, epoxy, acrylic yarn, water-based acrylic, or epoxy can be used.

The preferred climber for this purpose is a solvent-type polyester yarn brider.The powder coating used in the present invention is a powder coating mainly composed of acrylic, epoxy, or polyester resins, and particularly preferred are: It is a polyester powder coating.

Hereinafter, a typical coating method for high-processing steel according to the present invention will be explained in detail.

First, the base steel plate is generally pretreated according to conventional methods. Although the pretreatment method is not particularly specified, it can be carried out in the usual order, for example, degreasing, washing with water, chemical conversion coating treatment, and washing with water.

After completing the 11J treatment, drain and dry, and apply a solvent-based brimer with a light color or a dark color similar to the finishing dark color, which has excellent adhesion and processability, using a drying thickness of 1-200 ml using a roll coater, for example. 10j, preferably 5 to 7 μKm, and air dry or #'i baking. As the primer, as mentioned above, vC1 water-based paint can be used in addition to solvent-based paint, and the planting method can also be applied by coating with a roll coater, spray painting, coating with a curtain coater, etc. I can do it.

Next, this Zolaimer coating film is finished by applying a dark colored top coat powder pigment to a dry thickness of 2° to 50 μm, preferably 30 to 40 μm, by electrostatic powder shaking, for example.

According to the present invention, it is possible to use a pre-coat method using powder paint within a film thickness range with good moldability, and as shown in the table below, by making the powder paint film thinner and more uniform, unit surface We were able to reduce the amount of equipment used for paint per m (m''), and achieved a cost reduction that was greater than expected.Compared to the historical case of solvent-based paints, solvent emissions were reduced to #IIFi.

According to the present invention, it is further possible to introduce a flat plate coating system, and the product solvent-based L' width coating line can be made similar to the number of products, which is highly effective in improving the working environment and preventing pollution. Vise bending test (OT/
The steel plate coated according to the present invention, which showed no cracks at temperatures (30°C) and no abnormality was found in tests using a trench debon impact tester (500 f x soil φ x 50 cm), can be used, for example, in refrigerators, washing machines, etc. I was able to actually use it.

The present invention will be explained in detail below.

Example, 1 Leaf steel plate (Irofune plated steel plate, 0.6 bath thickness, 700 x 20
001) was degreased and then subjected to phosphoric acid film conversion treatment, and a solvent-type lower elm primer (Nippebra Coat Primer 413, manufactured by Nippon Paint Co., Ltd.) having the following composition was coated with a low odor coater to a dry thickness of 5 to 7 μm.

1. '1. White component Part by weight Titanium white pigment 10.0 Polyester resin 18.0 Amino resin
3.0 bath agent
68.9 Additives 0.1 100.0 This coating film is baked at 200°C for 1 minute, and then a top coating powder of light color (hue: almond) and dark color (hue: red, yellow) of the following composition is applied on top of it. The body paint (Nibbe Preco 300 manufactured by Nippon Paint Co., Ltd.) was electrostatically powder coated.

Ingredients Weight part: 4j machine material 5.0 wood
Fat 78.0 Hardening agent
15.0 Additives 2.0 100:0 Bake the coating at 230°C for 5 minutes.

The coating film obtained in this way was tested for concealment, processing resistance, and impact resistance, and the following results were obtained.

1.-Margin fruit! t11 seconds 1] 2 The raw material copper plate used in Example 1 was subjected to image processing in the same manner as in Example 1, and a primer was applied to it. This coating film has 5 molecules at room temperature! 11, and then electrostatically powder coated with the dark colored (hue: red) powder paint used in Minoru & @x, and baked at 230°C for 5 minutes.

The physical properties of the thus obtained 2-coat, 1-bake coating (film thickness; underline film thickness: 5 to 7 μm, 1-layer covert film thickness: 40 to 45 μm) were the same as in Example 1, resulting in high side illumination. The result was the following abstract.

Processability: OT Impact resistance: 50 countries

[Brief explanation of drawings]

Figure 1 shows the R series (red) light colors of the Munsell chromaticity table and *,
This is a drawing showing the distinction between the two colors, and the second one is a drawing showing the distinction between light and dark colors of Y yarn (several colors) in the Munsell chromaticity table, and the third drawing is a drawing showing the difference between the Munsell chromaticity table. Fig. 2 is a diagram m1 showing the distinction between light color and dark color of B yarn (blue). In each drawing, area A shows a light color, and area B shows a dark color. Patent applicant Nihon Pe4nt Co., Ltd. Patent agent Akira Aoki Patent attorney Kazuyuki Nishidate Patent attorney Ishi 1) Patent attorney Akira Yamaguchi 12-page semi-3 drawing

Claims (1)

[Claims] 1. When finishing the object to be painted in a light color with powder coating,
Apply Ply i- of light color or OiI color similar to the above-mentioned dark color, heat and cure as necessary in the next V, and finish with powder paint OII color to a film thickness of 20 to 50μ. Features a coating method for metal plates for high processing.