JPS61157697A - Formation of colored paint film by electrodeposition - Google Patents

Abstract

PURPOSE:To obtain a colored paint film having superior chemical and weather resistances by electrodeposition by forming a clear paint film on a metallic article to be treated by electrodeposition, drying and baking the film, coloring it by immersion in a coloring soln., and drying and baking the colored film. CONSTITUTION:A clear paint film is formed on a metallic article to be treated by electrodeposition with paint for electrodeposition such as epoxy resin or acrylic resin paint. The film is dried and baked at 120-180 deg.C for 5-30min, and it is colored by immersion in a coloring soln. contg. a dye or a pigment. The colored film is dried and baked at 160-180 deg.C for about 10min.

Description

DETAILED DESCRIPTION OF THE INVENTION Industrial Application The present invention relates to a method for forming a colored electrodeposition coating, and more specifically, it improves various properties such as chemical resistance, corrosion resistance, weather resistance, etc., and also provides an even and clean coating. The present invention relates to a method for obtaining colored electrodeposition coatings.

Prior art and conventional techniques When forming a colored film on a metal object to be treated by electrocoating, a method of obtaining a colored film has been carried out using a solution containing a dye or pigment mixed in a N coating bath. However, in order to obtain colored coatings of various different tones, it is inconvenient that an electrodeposition coating bath containing as many different dyes or pigments as the number of different tones is mixed is required, and the colored coatings formed are has various drawbacks, such as the tendency to cause unevenness in color tone. Therefore, in order to solve this problem, a clear electrodeposited film is formed on the metal object to be treated, and after baking and drying, the film is immersed in a colored liquid containing dye or pigment to remove the colored film. However, conventional methods of this type have problems in terms of dyeing speed, and the properties of the colored film formed, especially chemical resistance, corrosion resistance, weather resistance, etc., are insufficient. have. Therefore, there has been a strong demand for a colored electrodeposition coating that has a fast dyeing speed, allows deep dyeing in a short period of time, and has good coating properties such as chemical resistance, corrosion resistance, and weather resistance.

11 rows 1” As a result of extensive research in order to meet the above requirements, the inventor of the present invention formed a clear N-coated coating on the metal object to be treated.
After baking and drying this coating, immersing it in a coloring liquid containing a dye or pigment to color the coating, and then baking and drying this coating again, the dyeing speed becomes faster and dyeing can be done in a short time. Moreover, it has been found that deep dyeing can be achieved in a short period of time, and therefore coloring treatment can be carried out advantageously. Furthermore, by baking and drying the electrodeposited coating that has been colored after baking and drying in this way, the properties of the coating are improved and the chemical resistance (alkali resistance, acid resistance, solvent resistance) is improved. The present invention was based on the discovery that corrosion resistance and weather resistance are improved, as well as hardness.

The present invention will be explained in more detail below.

The method of forming a colored electrodeposited film according to the present invention is to apply a clear electrodeposition coating to the metal object to be treated, bake dry this wet coating under various conditions, and then immerse it in a dye solution. After dyeing, baking and drying is performed again to form a colored electrodeposition coating.

Here, there is no restriction on the type of metal object to be treated on which a colored electrodeposition coating is formed, and any metal object may be treated as long as it has an electrodeposition coating.For example, metals such as steel and copper, etc. In addition to those with a plating film formed on them, those made of a non-conductor such as plastic with a metalized surface are also used.

Further, as the electrodeposition paint for forming a clear electrodeposition coating, a known paint that provides a clear coating, such as an epoxy resin type or an acrylic resin type, can be used.

Furthermore, there are cationic electrodeposition coatings and anionic electrodeposition coatings.
Although any type of R-coating may be used, it is preferable to use a cationic electrodeposition coating method in which the metal object to be treated is used as a cathode in order to avoid metal elution and provide a beautiful coating film. however,
When aluminum or an aluminum alloy material is used as the metal object to be treated, an anionic coating method can be suitably employed.

The conditions for electrodeposition coating are not particularly limited, and known conditions such as bath voltage of 50 to 150 V and current application time of 1 to 3 minutes are adopted, and the clear coating film is usually formed to a thickness of 5 to 25 μm. .

In this way, the present invention provides a clear r
! After coating with 7i coating, the coating is baked and dried. The baking conditions are not particularly limited, but are usually 120 to 180°C, especially 170 to 180°C.
for 5 to 30 minutes, especially for 15 to 30 minutes.

In this case, the lower the baking drying temperature and the shorter the drying time, the faster the dyeing speed in the film dyeing step, and the darker the film will be dyed.

In the present invention, a clear electrodeposited coating is formed as described above, baked and dried, and then the painted coating is immersed in a colored liquid containing a dye or pigment.

Here, the types of dyes and pigments are not particularly limited, but when using dyes in the coloring liquid, it is preferable to use basic dyes when the clear coating film is formed from a cationic electrodeposition coating bath; When formed from a coating bath, it is preferred to use acidic dyes. Incidentally, the disperse dye can be used for those formed from either cationic or anionic coating baths. Further, when a pigment is used in the coloring liquid, the clear coating film may be formed from either a cationic or anionic coating bath.

After forming a clear paint film in this manner, it is baked and dried, immersed in a colored liquid, and then dried and cured to obtain a beautiful colored film having various tones corresponding to the colored liquid. Note that the conditions for immersion in the colored liquid are not necessarily limited, but conditions for immersion in a normal bath at 130 to 60° C. for 1 to 30 minutes may be adopted. in this case,
By changing the bath temperature and immersion time, it is possible to form colored films with various tones of different Ll;l lightness.

Next, in the present invention, the electrodeposited coating undergoes the second baking drying process after passing through the above-described first baking drying and dyeing process.

Here, the second baking drying conditions are not particularly limited, but are similar to the above-mentioned first baking drying conditions, that is, usually 120 to 180°C, especially 170 to 180°C.
Preferably, the conditions are 5 to 30 minutes, particularly 1 to 15 minutes. In this case, it is preferable that the conditions of the second baking drying step are appropriately selected according to the conditions of the first baking drying step, etc. For example, the conditions of the first baking drying step are
If the conditions are 60 to 180°C for 15 to 30 minutes, the second baking drying conditions are preferably 160 to 180°C for 10 minutes, and longer times are not necessarily required. Further, if the first baking drying conditions are lower than the normal temperature and for a short time, then the second baking drying conditions are preferably 160 to 180° C. for about 20 minutes.

Akane 1f JOL grade] According to the present invention, the electrodeposited coating is baked and dried, dyed, and then baked and dried again, so that the coating has chemical resistance, corrosion resistance, weather resistance, etc. It is possible to obtain a colored electrodeposited coating film, which has a fast dyeing speed, and has a deep color tone.

That is, a colored electrodeposition coating film formed by a conventional method by baking and drying the electrodeposition coating film and then dyeing it;
Comparing the chemical resistance and weather resistance of the colored IT electrodeposited coating according to the present invention, which undergoes two baking-drying processes: baking-drying, dyeing (), and baking-drying again, Table 1 shows that The method of the invention significantly improves the properties of colored electrodeposition coatings, and provides uniform and beautiful colored electrodeposition coatings.

EXAMPLES Hereinafter, the present invention will be specifically explained with reference to examples, but the present invention is not limited to the following examples.

[Example, Comparative Example] Acrylic cationic clear electrodeposition coating bath (non-volatile content: 1
0%), a stainless steel plate was used as the anode, and a steel plate with a bright nickel film formed by a known method was used as the metal object to be treated as the cathode. A clear electrodeposition coating film (thickness: 15 μm) was formed on the metal object to be treated.

Next, this electrodeposition coating film was baked and dried at 175° C. for 15 minutes (first time) to heat cure it. Thereafter, this film was colored by immersing it in a coloring liquid containing a red spirit dye (dye concentration: 5/J) at a temperature of 50°C for 10 minutes, and was then baked and dried again at 175°C for 25 minutes (second time). ) to obtain a red transparent colored electrodeposition coating (Example).

For comparison, a clear electrodeposition coating film formed in the same manner as in Section -F was baked and dried at 175° C. for 25 minutes to heat cure it. Next, it was immersed in a colored solution containing the same red spirit dye as above at 60°C for 20 minutes to obtain a transparent colored electrocoated coating with the same density as the electrocoated wave B of the above example. example).

Various physical property tests were conducted on the samples of Examples and Comparative Examples thus obtained, and the results are shown in Table 2.

From the results in Table 2, it is found that the dye-colored electric coating film produced by the method of the present invention has significantly improved chemical resistance, corrosion resistance, and #4 weatherability compared to the conventional method.

Claims (1)

[Claims] 1. Form a clear electrodeposited coating on the metal object to be treated,
A method for forming a colored electrodeposited film, which comprises baking and drying the film, immersing it in a coloring solution containing a dye or pigment to color the film, and then baking and drying the film again. .