Metal shell double-color anodic oxidation treatment process utilizing protective film shielding

Abstract

The invention provides a double-color anodic oxidation treatment process for a metal shell shielded by a protective film, and relates to the field of surface treatment.The double-color anodic oxidation treatment process comprises the following steps that S1, anodic oxidation coloring is conducted for the first time; s2, shielding treatment; s3, fading treatment; and S4, secondary anodic oxidation coloring. According to the treatment process, the cost is low, metal shells of various different color systems can be manufactured, the color is stable, a double-color boundary is clear and straight, a double-color area has metallic luster after secondary anodizing, the appearance is good, the production speed can reach 2 PCS / min, the manufacturing procedure is stable, and the yield is high.

Description

Technical Field

[0001] The invention relates to the field of surface treatment, and in particular to a two-color anodizing process for a metal shell shielded by a protective film. Background Art

[0002] Anodizing is an electrochemical oxidation process, mainly used for the surface treatment of metals or alloys, especially aluminum and its alloys. With the metal or alloy workpiece as the anode, an oxide film is formed on the metal or alloy surface by the action of an external current in a specific electrolyte. The oxide film has a porous structure. When the surface of the anodized product is immersed in a solution containing a dye, the dye penetrates and adsorbs on the pore surface of the anodized film, thus achieving the dyeing of the metal product.

[0003] In order to enrich the diversity of metal shell colors and designs, and to achieve a two-color or multi-color style on the metal surface, the metal shell needs to be dyed more than twice. The two-color anodizing technology is to form two layers of oxide layers of different colors in the same area or different areas on the metal surface to achieve a unique two-color effect, while improving the corrosion resistance and aesthetics of the metal. Patent 201810231321.0 discloses a two-color anodizing method for aluminum alloys and aluminum alloy structural parts, which first perform a first anodizing and coloring treatment; after removing part of the oxide layer, the part without the oxide layer is subjected to a second anodizing and coloring treatment. The surface of the aluminum alloy structural part can present a variety of appearance effects. Patent 202110036180.9 discloses a two-color anodizing manufacturing method, which first performs overall sandblasting, first anodizing, overall ink spraying and masking, laser carving to remove the ink layer and the anode layer, sandblasting, second anodizing, and ink removal. The processing method has a simple process, is more convenient to operate, has high processing efficiency, and has high dimensional tolerance accuracy.

[0004] The current two-color anodizing process still has problems such as unclear boundary between the two colors, low yield, and low efficiency. Summary of the invention

[0005] The purpose of the present invention is to provide a two-color anodizing process for a metal shell using a protective film for shielding. Through two anodizing operations, a two-color process with stable color can be formed on the metal shell. Combined with the shielding of the protective film and the cutting and separation of the glue, the two-color boundary line is clear and straight.

[0006] The present invention solves the technical problem by adopting the following technical solutions.

[0007] On the one hand, an embodiment of the present invention provides a two-color anodizing process for a metal shell using a protective film for shielding, comprising the following steps:

[0008] S1: First anodizing and coloring: chemical polishing treatment is performed on the surface of the metal shell, followed by first anodizing, and then coloring treatment is performed to form the first color on the surface of the metal shell, sealing the holes, and baking;

[0009] S2 masking treatment: Cover the area on the metal shell where the first color needs to be retained with a protective film, apply sealing glue on the edge of the protective film to seal the protective film, and after the sealing glue is cured, cut the sealing glue along the boundary line of the first color, retain the sealing glue on the first color area, and remove the rest of the sealing glue;

[0010] S3 fading treatment: placing the metal shell treated in step S2 in an anode fading battery for fading treatment to remove the first color of the area not covered by the protective film to form a fading area; baking;

[0011] S4 Second anodizing and coloring: Remove the protective film and sealant, perform chemical polishing on the surface of the metal shell, then perform a second anodizing, and then perform coloring to form a second color on the faded area on the surface of the metal shell, seal the holes, and bake.

[0012] In some embodiments of the present invention, the material of the protective film is a PET protective film that is resistant to acid and alkali liquids and has high viscosity and is relatively hard. PET is the abbreviation of polyethylene terephthalate.

[0013] In some embodiments of the present invention, the sealant is made of a material resistant to anodic acid and alkali liquid, specifically UV curing glue. The sealant is applied to the edge of the protective film to prevent the anodic acid and alkali liquid from penetrating into the protective film, so as to prevent the first color in the protective film from being removed during the fading process, thereby ensuring the integrity of the color.

[0014] In some embodiments of the present invention, in the step S1, before chemical polishing, it also includes: degreasing, alkali biting and black film stripping treatment.

[0015] In some embodiments of the present invention, in step S4, after removing the protective film and before chemical polishing, degreasing, alkali biting and black film stripping are also included. Alkali biting is to use the chemical properties of strong alkali to produce a chemical reaction between the aluminum alloy surface and the oxide layer to remove the oxide layer, and at the same time, it can also remove dirt such as oil, grease, dust, etc. on the aluminum alloy surface, thereby obtaining a clean aluminum alloy surface.

[0016] In some embodiments of the present invention, in step S2, an infrared laser machine is used to cut the sealant. The infrared laser machine is used for cutting, and with the programming of the laser machine, it can accurately cut along the boundary line, ensuring that the boundary line is accurate, straight, and has a small error.

[0017] In some embodiments of the present invention, the baking temperature is 70° C. to 80° C. By baking, the volatile liquid on the surface of the metal shell is removed.

[0018] In some embodiments of the present invention, the electrolyte for the first anodization and the second anodization is a sulfuric acid solution with a mass fraction of 10-15%.

[0019] In some embodiments of the present invention, the coloring treatment is adsorption dyeing or electrolytic dyeing.

[0020] Compared with the prior art, the embodiments of the present invention have at least the following advantages or beneficial effects:

[0021] The two-color anodizing process for metal shells provided by the present invention has low cost, can produce metal shells of various colors, has stable colors, a clear and straight two-color boundary line, and the two-color area after secondary anode has metallic luster and good appearance. The production speed can reach 2PCS / min, the process is stable, and the yield is as high as 85%.

[0022] Specifically, a porous oxide film is formed on the surface of the metal shell through anodizing, and the porous structure facilitates the adhesion of pigments to achieve the dyeing of the metal shell; after the first dyeing, the area that needs to retain the first dyeing is protected by shielding with a protective film and sealing with glue, and then a de-energizing and fading treatment is performed. Under the action of the electrolyte, the color of the unshielded part is faded to expose the metal shell, and the color of the part that does not need the first dyeing is removed through the de-energizing and fading treatment, so as to facilitate the second anodizing and coloring on the metal surface to ensure that both colored areas have a metallic luster. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0024] Figure 1 is a two-color area division diagram of Example 1 of the present invention;

[0025] Figure 2 This is the first anodizing coloring process sequence in Example 1 of the present invention;

[0026] Figure 3 The second anodizing coloring process sequence in Example 1 of the present invention;

[0027] Figure 4 A metal shell obtained by the process of Example 1 of the present invention Figure 1 ;

[0028] Figure 5 A metal shell obtained by the process of Example 1 of the present invention Figure 2 ;

[0029] Figure 6 The second metal shell obtained by the process of Example 1 of the present invention Figure 1 ;

[0030] Figure 7 The second metal shell obtained by the process of Example 1 of the present invention Figure 2 ; DETAILED DESCRIPTION

[0031] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially.

[0032] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other. The present invention will be described in detail below with reference to specific embodiments.

[0033] The embodiment of the invention provides a two-color anodizing process for a metal shell using a protective film for shielding, comprising the following steps:

[0034] S1 The first anodizing coloring: degreasing, alkali biting, black film stripping, chemical polishing of the metal shell surface, followed by the first anodizing, and then coloring to form the first color on the metal shell surface, sealing, and baking; Among them, there are two types of coloring treatment, adsorption coloring: immersing the metal workpiece in the dye so that the oxide film pinholes absorb the dye, and electrolytic coloring: immersing the metal workpiece in an electrolytic coloring solution containing metal salts for AC (or DC) electrolysis to color the oxide film.

[0035] S2 masking treatment: Cover the area on the metal shell where the first color needs to be retained with an acid- and alkali-resistant PET protective film, and apply an anodic acid- and alkali-resistant UV glue to seal the edge of the protective film to seal the protective film. After the sealing glue is cured, use an infrared laser machine to cut the sealing glue along the boundary line of the first color, retain the sealing glue on the first color area, and remove the remaining sealing glue; the sealing glue used in the present invention can be 8010UV light-curing epoxy resin glue, CRCBOND UV glue, or other anodic acid- and alkali-resistant UV glue.

[0036] S3 fading treatment: placing the metal shell treated in step S2 in the anode fading battery for fading treatment to remove the first color of the area not covered by the protective film to form a faded area; baking at 70-80°C; preferably, the baking temperature is 70°C, and can also be 75°C or 80°C.

[0037] Among them, the principle of electrolytic fading in anodic stripping is: placing the metal shell in an electrolyte (the specific electrolytic stripping electrolyte formula needs to be adjusted according to different metal coatings and substrates) for electrolysis, so that the plated metal undergoes oxidation or reduction reaction on the electrode, thereby dissolving in the electrolyte, causing the coating and the color on the coating to fall off, exposing the original surface of the metal shell.

[0038] S4 Second anodizing and coloring: tear off the protective film and sealing glue, degrease, alkali bite, peel off the black film, chemically polish the surface of the metal shell, then perform a second anodizing, and then perform a coloring treatment to form a second color in the faded area on the surface of the metal shell, seal the holes, and bake at 70-80°C. Preferably, the baking temperature is 70°C, and can also be 75°C or 80°C.

[0039] The electrolyte in the first anodization and the second anodization is a 10-15% sulfuric acid solution at 25°C, and the coating formation rate is about 25m / hr. The coating formation rate can be adjusted according to different metal coatings and different metal substrates.

[0040] The sealing in steps S1 and S4 is to form tiny pits on the metal surface through electrochemical reactions, which will then expand and form a complete oxide layer to seal the small holes formed during the anodizing process; after the sealing in step S1, the part blocked by the protective film has not been subjected to the de-electrolysis and discoloration treatment, and this part will not react in step S4. In the embodiment of the present invention, the sealing treatment can also be hydrated sealing, metal salt sealing, room temperature sealing, organic coating sealing, etc.

[0041] The features and performance of the present invention are further described in detail below in conjunction with the embodiments.

[0042] Example

[0043] Follow the steps below to perform two-color anodizing on the notebook metal shell (aluminum alloy): Figure 1 , red and black are the twice colored areas.

[0044] S1 The first anodizing coloring: degreasing, alkali biting, black film stripping, chemical polishing of the metal shell surface, followed by the first anodizing. The first anodizing process parameters are: using 15% sulfuric acid solution at 25°C, the coating formation rate is about 25m / hr.

[0045] Then, the coloring treatment is carried out. The coloring treatment process is as follows: adsorption dyeing, immersing the metal shell in black dye, allowing the oxide film pinholes on the surface of the metal shell to adsorb the dye, forming the first color on the surface of the metal shell, electrolytic sealing, and baking at 70°C; the process sequence is as follows Figure 2 shown.

[0046] S2 shielding treatment: according to the attached Figure 1 According to the size of the red area of ​​the inner cavity marked in the drawing, two pieces of acid- and alkali-resistant PET protective films are cut out. Using a jig, the cut protective films are attached to cover the front and back of the red area of ​​the inner cavity of the notebook metal shell; then the notebook metal shell is placed on the dispensing machine jig with the front facing up, and the dispensing machine is programmed along the boundary of the two-color area marked on the drawing, and then acid- and alkali-resistant UV glue is applied for sealing; the notebook metal shell coated with sealing glue is placed under a UV lamp for curing. Turn the notebook metal shell over again, with the back facing up, and place it on the dispensing machine jig to apply sealing glue on the edge of the protective film, and then place the notebook metal shell coated with sealing glue under a UV lamp for curing again. Place the front of the metal shell on the fixture of the infrared laser machine, and program the laser machine along the boundary of the two-color area marked on the drawing, infrared cut the sealing glue, and split the sealing glue, and then tear off the sealing glue on the side that is not covered by the protective film along the cut line.

[0047] S3 fading treatment: hang the metal shell and place it in the anode fading battery for fading treatment to remove the first color of the area not covered by the protective film, present the original color of the metal, and form a fading area; bake at 70℃;

[0048] S4 Second anodizing and coloring: tear off the protective film and sealing glue, degrease, alkali bite, peel off the black film, chemically polish the surface of the metal shell, then perform a second anodizing, and then perform coloring (adsorption dyeing, immersing the metal shell in golden dye), forming a second color in the faded area on the surface of the metal shell, electrolytic sealing, and baking. The process sequence is as follows: Figure 3 The second anodizing process parameters are: 15% sulfuric acid solution at 25°C, and a coating formation rate of about 25 m / hr.

[0049] The metal shell of the notebook prepared by the above process is as follows Figure 4-5 shown.

[0050] Comparative Example 1

[0051] The metal shell is colored using the traditional two-color ink process, specifically: after the metal shell is surface treated according to the method of Example 1, a single-color topcoat is sprayed for the first time, a protective film is applied to cover the second color to be coated, a two-color topcoat is sprayed for the second time, the film is torn off, printing is performed, and gold oil is applied for protection.

[0052] Comparative Example 2

[0053] The difference from Example 1 is that a laser engraving process is used to replace the protective film and glue masking in Example 1, and the laser engraving process is used to remove the color of the part that does not need the first dyeing, and then the second dyeing is performed. The remaining steps are the same as Example 1.

[0054] Experimental example

[0055] The metal shell of the notebook was subjected to a two-color treatment using the processes of Example 1 and Comparative Examples 1-2, and the yield and efficiency of each process were statistically analyzed. The results are shown in Table 1.

[0056] Table 1 Yield and efficiency of each two-color processing process

[0057]

[0058]

[0059] It can be concluded from Table 1 that the two-color processing technology provided in Example 1 has a yield rate of 85% and an efficiency of 2 PCS / min. It has a fast processing rate and a high product yield. Figure 4-7 The notebook metal shell treated by the process of Example 1 has a stable color, a clear and straight two-color boundary line, and a metallic luster in the two-color area after the secondary anode, and a good appearance.

[0060] The embodiments described above are part of the embodiments of the present invention, rather than all of the embodiments. The detailed description of the embodiments of the present invention is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

Claims

1. A two-color anodizing process for a metal shell using a protective film shield, characterized in that: The following steps are involved: S1: First anodizing and coloring: chemical polishing treatment is performed on the surface of the metal shell, followed by first anodizing, and then coloring treatment is performed to form the first color on the surface of the metal shell, sealing the holes, and baking; S2 masking treatment: Cover the area on the metal shell where the first color needs to be retained with a protective film, apply sealing glue on the edge of the protective film to seal the protective film, and after the sealing glue is cured, cut the sealing glue along the boundary line of the first color, retain the sealing glue on the first color area, and remove the rest of the sealing glue; S3 fading treatment: placing the metal shell treated in step S2 in an anode fading battery for fading treatment to remove the first color of the area not covered by the protective film to form a fading area; baking ； S4 Second anodizing and coloring: Remove the protective film and sealant, perform chemical polishing on the surface of the metal shell, then perform a second anodizing, and then perform coloring to form a second color on the faded area on the surface of the metal shell, seal the holes, and bake.

2. The two-color anodizing process for metal shells shielded by protective film according to claim 1 is characterized in that: The material of the protective film is PET.

3. The two-color anodizing process for metal shells shielded by protective film according to claim 1, characterized in that: The sealing glue is acid and alkali resistant UV curing glue.

4. The two-color anodizing process for metal shells shielded by protective film according to claim 1, characterized in that: In the step S1, before chemical polishing, the process also includes: degreasing, alkali biting and black film stripping.

5. The two-color anodizing process for metal shells shielded by protective film according to claim 1, characterized in that: In the step S4, after removing the protective film and before chemical polishing, degreasing, alkali biting and black film stripping are also included.

6. The two-color anodizing process for metal shells shielded by protective film according to claim 1, characterized in that: In step S2, the sealing glue is cut using an infrared laser machine.

7. The two-color anodizing process for metal shells shielded by protective film according to claim 1, characterized in that: The baking temperature is 70℃-80℃.

8. The two-color anodizing process for metal shells shielded by protective film according to claim 1, characterized in that: The electrolyte for the first anodization and the second anodization is a sulfuric acid solution with a mass fraction of 10-15%.

9. The two-color anodizing process for metal shells shielded by protective film according to claim 1, characterized in that: The coloring treatment is adsorption dyeing or electrolytic dyeing.

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