JPS6015705B2 - How to partially color metal - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for partially coloring metal, in which pattern-shaped recesses are formed on a metal surface, and a plating layer of metal having a hue different from that of the metal is precisely applied to the recesses.

Traditionally, there are conventional painting methods, printing methods, and transfer methods for coloring weather-resistant metals such as stainless steel and aluminum.However, in this case, the colored layer is applied to the flat surface of the metal plate. It simply adheres to a certain thickness, and the adhesion strength between the ink and paint and the metal surface is low.
Because it is susceptible to external friction and impact, the colored layer sometimes peels off.

In addition, in this method, etching and cutting press processing are performed after the colored layer is provided, so there is a problem in that the pattern formed by the colored layer and the cutting process cannot be precisely aligned. On the other hand, as another coloring method, there is a method in which one side of a metal plate is etched in advance and a colored resin such as melamine resin is embedded in the recessed part. However, this method requires manual work to fill the resin into the recesses, making it difficult to achieve accuracy and not being suitable for mass production. In addition, the colored resin layer swells and weakens due to water or solvent, and inevitably peels off due to friction or sticking. The present invention is a method for partially coloring metal that overcomes the drawbacks of the prior art as described above, and specifically, it involves forming a non-conductive resist film in a desired pattern on a metal surface, and applying color to the non-conductive resist film. After etching the uncovered metal exposed surface to an appropriate depth to form pattern recesses,
With the non-conductive resist film still attached, a colored plating layer having a color different from that of metal is formed in the concave portions of the pattern by electrolytic plating, and then the non-conductive resist film is removed. This is a method for partially coloring metal.

A detailed explanation based on drawings showing embodiments of the present invention:
As shown in FIG. 1, a metal plate 1 to be partially colored is formed by applying a non-conductive resist film 2 having openings 3 in a desired pattern on its surface.

The resist film 2 can be formed by printing etching-resistant printing ink on the metal plate 1 using a screen printing method, or by applying a photosensitive resin to the entire surface of the metal plate 1 and printing the pattern through an original film having a light-shielding pattern. This can be done by a conventionally known method of exposing the image to light and then printing it in a twill pattern. Inks and photopolymer resins are typically non-conductive, which is advantageous for the present invention. The shape of the barrier part 3 is
It corresponds to shapes that will be colored in the future. It goes without saying that the corrosion-resistant film 4 applied to the back surface of the metal plate 1 prevents the metal plate 1 from being etched from the back surface. Subsequently, as shown in FIG. 2, the portions of the metal plate 1 exposed by the barrier holes 3 are etched by means such as chemical etching or electrolytic etching to form recesses 5.

The depth d of the recess 5 may be appropriately determined based on the thickness of the metal plate 1, the size of the opening 3, etc. Subsequently, as shown in FIG.
to form within. The thickness of the star-colored plating layer 6 is set smaller than the depth d of the recess 5 so that it does not protrude from the recess 5. When applying the colored plating layer 6, since the resist film 2 is a non-conductive material, no plating layer is formed on the surface covered by the resist film 2. Therefore, the colored plating layer 6 is applied only to the recessed portion 5. The meaning of the color of the colored plating layer 6 here is that it is different from the color of the surface of the metal plate 1, and if the metal plate 1 has a silvery white color, for example, it has a color of black, brown, red, etc. It is preferable to form a metal plating layer. Specifically, these include black chrome plating, blackened nickel plating, copper plating, etc. However, the contrast, color stability, and hardness after plating are high (black chrome plating is the most prized in terms of wear resistance). Subsequently, the resist film 2 may be removed with an alkaline solution, a solvent, etc., and the entire surface of the metal plate 1 may be coated with a transparent resin to provide a surface protection layer 7, as shown in FIG. At this time, the transparent resin can be applied by any known means such as spray coating, electrostatic coating, dew coating, and flow coater. The surface protective layer 7 may or may not be present, but if the surface protective layer 7 is provided, the gloss of the material surface can be adjusted (it can be adjusted by adding a matting agent).
It is also possible to prevent stains such as fingerprints from adhering to the metal surface, and to prevent changes in the black chrome layer 5 due to fading due to sunlight. The present invention is as described above, and according to the present invention, the black chrome plating layer is applied to the etched recesses, so it is less susceptible to external friction and impact. Since it is applied to a rough surface, the plating layer has strong adhesion to the metal plate.

Moreover, compared to the colored resin layer, the plating layer does not swell with water, organic solvents, oils, etc., and is highly durable and difficult to peel off. Moreover, according to the present invention, the resist film used when forming the etching recesses also acts as an insulating film during plating, and the star-colored plating layer can be precisely applied only to the recesses, so the resist film has a dual role. The savings in the process by doing this can also be said to be a big effect.
Examples of the present invention will be described below.

〔Example〕

A 0.3 willow thick stainless steel plate (S female 304) was exposed to polyvinyl alcohol monoammonium chromate. A non-conductive resist film having a pattern of openings was formed by uniformly applying a conductive resin, exposing to light through a negative original mask having a desired light-shielding pattern, and developing it.

Next, the exposed surface of the stainless steel plate was etched to a depth of 100 microns using a ferric chloride solution with a Baume concentration of 42o and a temperature of 45qo to form a recess. Continuing further, this material was prepared in the following rich composition at a liquid temperature of 15°C and a current density of 10 hA/.
Black chrome plating was carried out for 5 minutes, and a colored plating layer was applied inside the etched recesses. Chromic anhydride
400 evening/so 33% Katsura hydrofluoric acid 35
0 evening/Then, 30% caustic soda solution (temperature 1100
0) to dissolve and remove the resist film, wash and dry, then a transparent varnish (trade name: ST-1 eaves (manufactured by Hamani Kasei Co., Ltd.)) was applied by spray coating to form a surface protective layer.

[Brief explanation of drawings]

1 to 4 are enlarged partial sectional views showing an example of the partial coloring method of the present invention in the order of steps. 1... Metal plate, 2... Non-conductive resist, 3...
Openings, 4... Corrosion resistant film, 5... Recesses, 6... Star-colored plating layer, 7... Surface protective layer. *1 Zuren 2 Zumai 3 diagrams *4 Diagrams

Claims (1)

[Scope of Claims] 1. After forming a non-conductive resist film in a desired pattern on a metal surface and etching the exposed metal surface not covered by the resist film to an appropriate depth to form a pattern recess, A colored plating layer having a thickness thinner than the depth of the pattern recesses is formed in the pattern recesses by electrolytic plating with the conductive resist film still attached, and then the non-conductive resist film is removed. A distinctive method of partially coloring metal. 2. The method for partially coloring metal according to claim 1, wherein the coloring plating layer is a black chrome plating layer.