JPH034638B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for forming a golden coating film with excellent weather resistance on the surface of a shiny metallic article. Shiny metallic articles, such as articles made of aluminum, iron, copper, stainless steel, etc., or articles whose surfaces are plated with nickel, chrome, etc., and furthermore, the mixing of metal powder, etc. imparts conductivity by
Products with metal plating on their surfaces are widely used in various mechanical devices, electronic devices, consumer electrical appliances, etc. The surface of such metallic objects has a cold metallic luster, so the purpose is to reduce the luster, or to add various colors to the original metallic luster, or to oxidize the surface of these objects. Surface coatings are applied for the purpose of protection from oxidation and sulfurization, or for a combination of these purposes. For example, according to a proposal in JP-A-57-115466, an electrodeposition paint containing a dye is applied to a white metal surface by electrodeposition. However, in this case, due to the characteristics of the dye, the color fades dramatically due to ultraviolet rays, so it is difficult to apply it to articles used outdoors, such as automobile bodies and eyeglass frames. The present invention has been made to solve these difficulties, and is a method for electrocoating metallic objects having a luster as described above in gold color using an electrocoating paint containing an organic pigment. It is characterized by this. It is possible to produce a chromatic luster using conventional plating techniques or alumite dyeing, but it is possible to produce a chromatic luster using brass, gold, black nickel, black chrome, or tin alloy plating other than light ink. cannot be obtained with current technology. Furthermore, although chromatic dyeing is possible with alumite dye, specular gloss cannot be obtained. Therefore, the only way to obtain a gold coating was through plating, such as gold plating or brass plating. However, regular gold plating is expensive and
It is highly abrasive, thin, has many pinholes, and corrosion of the underlying plating occurs, resulting in poor apparent corrosion resistance. The present inventors applied the fact that when a transparent colored coating is applied to an object with metallic luster, the luster (reflection) of the object is utilized and the appearance appears as if the metal was colored. By applying a yellow coating that has a spectral reflection curve very similar to gold to a metallic article with a metallic luster and a reflectance similar to that of gold, it is possible to create a gold-plated metal article that has a similar appearance to gold plating. It was discovered that a deposited coating film could be obtained, and the present invention was completed. Here, the term "metallic article" is meant to include not only articles made of metal as described above, but also articles made of synthetic resin that has been imparted with electrical conductivity to the extent that it can be plated. Specifically, it refers to a shiny metallic article made of iron, copper, stainless steel, etc., or plated with nickel, chromium, rhodium, or brass. The organic pigments used in the present invention include those with excellent light resistance, especially insoluble azo-based, phthalocyanine-based, metal complex-based, quinacridone-based, dioxazine-based, condensed azo-based, vat dye-based, isoindolinone-based, etc. There is no problem with any of the pigments, but it is best to select and combine pigments that give a yellow color. Soluble azo pigments are excluded because they have poor light resistance. In order to incorporate such an organic pigment into an electrodeposition paint, it is sufficient to simply weigh out a certain amount of it, add it to the paint, and stir it. Based on the experimental results of the present inventors, the amount added to 1 paint is usually 0.1 to 10
It is about g. In the present invention, even among the same pigments, inorganic pigments are excluded and organic pigments are adopted.The reason why inorganic pigments are inferior to organic pigments in color clarity and transparency, It is not in line with modern tastes, such as a complete loss of surface light selection and the existence of a metal surface at the bottom, which can be seen through its relaxed state, and that the same degree of coloration is not achieved. As a guideline, if inorganic pigments are added to a paint, the amount of inorganic pigments required to be added is several times that of organic pigments, which tends to impair the performance of the electrodeposition paint. This is because the ratio of vehicle to pigment in the electrodeposited coating film should be smaller as the film thickness becomes thinner. This is because when the amount of pigment increases, the bonding of the vehicle becomes weaker, and water resistance, solvent resistance, etc. decrease. Note that organic pigments have higher coloring properties than inorganic pigments as described above, but their prices are high, so it may be possible to reduce the amount used by blending inorganic pigments. In particular, when rutile titanium oxide, which is known as a white pigment, is used in combination, it is possible to produce pastel colors with good light resistance. The electrodeposition paint used in the present invention may be either anionic or cationic. As mentioned above, since organic pigments have high coloring properties and the amount added to the electrodeposition paint is extremely small, the amount added does not cause any particular change in the electrodeposition coating conditions. If the paint is anionic, the metal object to be coated is the anode,
If the paint is cationic, the object to be coated is a cathode,
It is sufficient to apply direct current at 20 to 100 V and current density of 0.1 to 2 A as usual. It is also possible to apply alternating current instead of direct current, but in that case, various mottled patterns will appear depending on the conditions. After the electrodeposition operation is completed, the coating film is of course subjected to a so-called baking process to harden it in the usual manner. As mentioned above, since the method of the present invention uses electrodeposition coating means, a coating film with a significantly more uniform thickness can be obtained compared to spray coating, dipping coating, or brush coating, and it is possible to coat the surface of the article with Even when there are minute irregularities such as hairlines, the original shape is excellently reproducible, and of course, even when the shape of the article is complex, its throwing power is good. Examples and comparative examples are given below. The materials of the article to be coated used are as follows. Brass plate 30 x 75 mm and 1 mm thick The type of pigment used is indicated by its common name ( )
Color index number (C, I, No.) inside
Also listed. Weather resistance test after coating film formation is JIS.K5400, 6-17
The accelerated weather resistance test method specified in . Example 1 Nickel plating 5μm, further rhodium plating
The above brass plate treated with 0.1 μm was used as the cathode, and permanent red FGR (CI12370) was used as the organic pigment.
0.2g/, and Hansa Yellow-G (C.
I.11680) 0.3g/solid substance 15
% water-dispersible cationic acrylic paint was used as the electrolytic bath. Electrodeposition conditions were 50V for 3 minutes, and baking conditions were 190℃ for 20 minutes. As a result, a gold-colored coating film was obtained, and a coating film that was indistinguishable from gold plating was formed. Comparative Example 1 The difference from Example 1 is that the cationic acrylic paint used in Example 1 was coated with a commercially available yellow dye, manufactured by BASF, trade name: Quinoline Yellow Extra.
This is a point that was spray-painted with Quinoline Yellow extra 0.3g/ added. The appearance of the formed coating film was similar to that of Example 1. Table 1 shows the results of the weather resistance test performed on the products of the above Examples and Comparative Examples.

[Table] FIG. 1 is a graph showing spectral reflectance curves of various plating films. It is understood that plating other than gold plating is achromatic plating that does not have a particular reflection wavelength range (absorption wavelength range). To put it simply, chrome plating has a reflection wavelength range of 400 to 500 nm, giving it a bluish tinge. Only gold plating shows a characteristic absorption characteristic curve,
It reflects wavelengths of 500 to 700 nm, and from Figure 2 it can be seen that it is a chromatic plating with yellow to red tones. The results are shown in Table 2.

[Table] The reflectance is around 80% for gold plating, and decreases as the layer progresses from Ag plating to Ni plating to polished Al fabric to Cr plating. This also indicates the brightness of the metal. Therefore, gold plating can be said to be a very bright yellow color. The spectral reflectance curve according to the present invention is shown in the graph of FIG. 3 when electrodeposition paint containing a yellow pigment is applied to these achromatic base platings (metallic). All of them have the same curve as gold plating, indicating that they have become chromatic. Although there are differences in reflectance,
All of them maintain their metallic luster, giving them a golden color. Visually, the influence of reflectance is large, so Ag
The plating base is the closest to gold plating, and the polished Al fabric has Ni plating, which makes it feel black, but it is fully practical as gold. When a chrome plating is used as a base, a bluish tinge is added as seen from the curve in Figure 1, and the reflectance is the lowest, making the color tone darker, so it has not been put to practical use. It can be seen that the properties of the gold electrodeposited coating film are quite close to those of gold plating in the three-attribute indication (JIS) and Munsell color system indications shown in Table 3. The index L ^* is increased due to the brightness of the base metal and the use of pigments with suppressed hiding properties, which are the characteristics of this case.

[Table] Here, the symbols in Table 2 above, L ^* , a ^* , b ^* are
Based on the JISZ8729 standard, it represents the brightness, the change in hue from red → ← blue, and the change in hue from yellow ← → green. From the above, it can be seen that maintaining metallic luster is the most important point, but glossiness is also important for aluminum anodic oxidation (alumite) coatings, which are often seen in the cited example, and the glossy aluminum plate and electrodeposition coating that will be used in this case. Table 4 shows a comparison of those coated with a glossy gold coating.

[Table] Here, the symbol "ED" in Table 4 above indicates electrodeposition coating, and the measurement method was in accordance with the standard of JISZ8741. Although it decreases somewhat due to electrocoating, it exhibits significantly higher gloss than alumite. Visually, it was confirmed that this value was almost the same as that of the abrasive material. It should be noted that the decrease in numerical value is caused by applying a coating film, and the decrease occurs not only by electrodeposition but also by placing transparent glass on an aluminum plate. The golden coating film obtained by the present invention is inexpensive, has good corrosion resistance, and the film thickness can be easily adjusted. Also,
It has a high shielding effect against atmospheric pollution, can be used against car exhaust gas, cosmetics, and moisture in bathrooms, does not fog or corrode, is easy to maintain, and has excellent durability.

[Brief explanation of the drawing]

FIGS. 1, 2, and 3 are graphs illustrating the characteristics of the gold electrodeposition coating method according to one embodiment of the present invention.

Claims (1)

[Scope of Claims] 1 Made of metal materials such as iron, copper, brass, stainless steel, and aluminum, or non-conductive materials subjected to conductive treatment, with nickel plating, chrome plating,
A lustrous metallic article with achromatic plating such as rhodium plating or palladium plating is coated with azo-based, phthalocyanine-based, metal complex type, quinacridone-based, dioxazine-based, condensed azo, etc. A golden electrodeposition coating film characterized by being electrodeposited using an electrodeposition paint containing about 0.1 to 10 g of pigments such as pigments based on dyes, vat dyes, or isoindolinones, mixed together to give a yellow color. How to form. 2. The method for forming a golden electrodeposited coating according to claim 1, wherein the pigment is an insoluble azo pigment. 3. The method for forming a golden electrodeposited coating according to claim 1, wherein the shiny metallic article is a plated article. 4. A golden electrodeposited coating according to claim 1, wherein the shiny metallic article is an article coated with nickel plating and/or achromatic plating such as rhodium plating or palladium plating. Formation method. 5. The method for forming a golden electrodeposited coating according to claim 1, wherein the coating material is a water-dispersible acrylic coating. 6. The method for forming a golden electrodeposition coating according to claim 1, wherein the paint is a water-dispersible cationic acrylic paint.