JP4093485B2 - Surface treatment method of aluminum alloy - Google Patents

Description

  The present invention forms a predetermined pattern by depositing a masking ink on the surface of an aluminum alloy, and uses the pattern as a mask to process the surface of the aluminum alloy into a concavo-convex shape, thereby expressing a pattern of characters, pictures, etc. The present invention relates to a surface treatment method.

  Conventionally, a method using a press die or a method using laser marking is known as a method for forming a concavo-convex shape on an aluminum alloy and expressing a pattern such as a character or a picture. According to the method using a press die, it is possible to mass-produce various designs in a short time as long as the die is manufactured. However, since mold costs are required, On the contrary, the production cost would increase. In addition, in the laser marking method, if a laser marking facility is provided, it is possible to meet minute design requirements and it is possible to respond sufficiently to small-lot, multi-product production. To make a pattern such as a pattern with a step of about 0.1 mm to 0.5 mm, it is very difficult to make a step with a single laser marking, and it takes time to make a step. It was necessary to take measures such as marking the same pattern over and over, resulting in a loss of productivity.

  Furthermore, as a method of making a pattern such as a letter, a pattern, etc. on an aluminum alloy with a step of about 0.1 mm to 0.5 mm, the letter is masked with a masking ink or the like, and a sodium hydroxide solution or chloride chloride is used. A method of forming an uneven shape by performing an etching process using an etchant such as 2 iron is known. In the method of forming the concavo-convex shape by performing this etching process, a screen printing method and a pad printing method that are inexpensive and can be used for mass production are often used as a method of forming the pattern with a masking ink. In addition, the etching method can freely adjust the step amount of the concavo-convex shape, and in order to make the concavo-convex shape with a step of about 0.1 mm to 0.5 mm in a short time, the etching solution It is also possible to perform the treatment in a short time by increasing the concentration of or increasing the temperature of the etching solution.

Also, if you want to make the uneven shape with a step of about 0.1 mm to 0.5 mm described above to have a more three-dimensional design, the pattern portion is blasted to form a fine uneven shape to give a glossy appearance. By making adjustments to enhance the pattern of characters, patterns, etc., or by using a mixed solution of ammonium fluoride and a substrate adjustment process (see, for example, Patent Document 1), the parting portion of the pattern is smoothly finished to achieve a more three-dimensional structure. There is a method to make a design with a feeling. On the other hand, as a method using a treatment agent containing a complex fluoride, a surface treatment method is disclosed in which a vertical bar on the surface of an aluminum alloy extruded product is left and only deep scratches other than the vertical bar are removed (for example, Patent Document 2). reference).
JP 7-176500 A JP-A-11-106970

  However, in the conventional technique, when a commercially available masking ink is used, it is difficult to smoothly finish the parting pattern of the pattern because of insufficient adhesion. Further, when the pattern portion is blasted after the etching process, the masking may be peeled off by the impact of a projection material such as glass beads.

  For masking peeling due to the impact of blasting treatment, masking ink for blasting and the like having excellent impact resistance is commercially available from ink manufacturers, but due to poor adhesion to metal, about 0.1 mm to 0.5 mm If the etching process to form the uneven shape of the step is performed, there are many problems such as masking peeling and the parting line when forming patterns such as letters and pictures are not finished fine, all these The condition could not be satisfied.

  Therefore, the present invention has been made in the background of the above circumstances, and in a surface treatment method for forming a design by masking with a pattern of characters, pictures, etc. on the surface of an aluminum alloy, An object of the present invention is to provide a simple and reproducible surface treatment method for smooth finishing, blasting and the like without masking peeling.

In order to solve the above technical problem, the present invention forms a predetermined pattern by depositing a masking ink on the surface of an aluminum alloy, performs a post-process using the pattern as a mask, and then removes the masking ink. In the surface treatment method for forming a pattern on the surface of the aluminum alloy, before the step of depositing the masking ink, a complex fluoride of 0.05 to 10 g / L as fluorine and 0.001 to 5 g / L of nitric acid are used. only free and was provided as a surface treatment method superior aluminum alloy adhesion properties of the masking ink, characterized by washing with a liquid which does not contain sulfuric acid.

  Preferably, the complex fluoride is one or more selected from the group consisting of zircon hydrofluoric acid, titanium hydrofluoric acid and zircon ammonium fluoride. Further, even when the subsequent process after the masking ink is applied is an etching process or a blasting process, a surface treatment method having excellent adhesion characteristics between the aluminum alloy and the masking ink can be obtained.

  According to the present invention, before depositing the masking ink on the aluminum alloy, it is only washed with a liquid containing 0.05 to 10 g / L of complex fluoride and 0.001 to 5 g / L of nitric acid as fluorine. Thus, without changing the conventional processing steps, the parting part of the pattern by the etching process can be smoothly finished, and the masking can be processed without peeling off by blasting or the like.

In the embodiment according to the present invention, zircon hydrofluoric acid H ₂ ZrF ₆ , titanium hydrofluoric acid H ₂ TiF ₆ , and zircon ammonium fluoride (NH ₄ ) ₂ ZrF ₆ can be used as the complex fluoride. These may be used alone or in combination. The amount of the complex fluoride used is 0.05 to 10 g / L, preferably 0.2 to 8 g / L, as fluorine. If the fluorine concentration is lower than 0.05 g / L, the adhesion of the masking ink cannot be ensured, and if it is used at a concentration higher than 10 g / L, the surface of the aluminum alloy becomes cloudy and the value as a product is impaired. Absent.

Further, the present invention has been decided to use a solution containing nitric acid 0.001 to 5 g / L, resulting effect of suppressing powdering phenomenon of aluminum alloy was degreased by adding nitric acid (HNO ₃₎ It is done. Preferably, it is used so that it may become 0.01-3.5 g / L nitric acid. In general, sulfuric acid is often used as the acid component of the degreasing agent, but in this embodiment, sulfuric acid is not added. That is, with the exception of inevitable traces of impurities, cleaning is performed before masking with a treatment solution containing only complex fluoride and nitric acid.

  This treatment liquid is used in the second or third water washing step performed after the degreasing treatment and the first water washing treatment. The liquid temperature is 40 to 85 ° C, preferably 45 to 55 ° C. The treatment time is 0.5 to 3 minutes, preferably 1 to 1.5 minutes. In the normal pretreatment such as degreasing, it is necessary to perform draining and drying before applying the masking ink, so the product is immersed in warm water of 60 to 90 ° C. and then drained and dried when it is pulled up (hereinafter referred to as the draining and drying process) However, according to the surface treatment liquid of the present invention, the second or third water washing step and the water washing drying step can be made common. That is, by using hot water of 60 to 90 ° C. as the surface treatment liquid of the present invention, two steps are simultaneously performed, and the number of treatment steps can be reduced. Therefore, it is possible to select conditions suitable for each working environment for the liquid temperature and the processing time.

  Various aluminum alloys can be applied as the aluminum alloy that can achieve the effect according to the present invention, and it is particularly suitable for a 5000 series aluminum alloy represented by a JIS5052 alloy and a 6000 series aluminum alloy represented by a JIS6063 alloy. In the present invention, the aluminum alloy includes aluminum.

  In this embodiment, as shown in FIG. 1, (a) material processing of an aluminum alloy, (b) pretreatment (degreasing process), (c) masking ink application / drying process, (d) etching process, (e) A blasting step, (f) an alumite step (only the etching portion), (g) a masking removal step, and (h) an alumite step (other than the etching portion) were sequentially performed. The work procedure described above is not limited to this. In practice, the process sequence and the like must be adjusted to match the product shape and the required design. In the step (c), a commercially available masking ink was used. Further, the masking ink deposited in the step (c) needs not to be removed by the (d) etching step and the (e) blast step, but needs to be removed in the subsequent (g) masking removal step. Therefore, an appropriate adhesion characteristic is required.

  Next, examples of the present invention will be specifically described in comparison with comparative examples. In this example, as the material processing of the aluminum alloy in the step (a), A6063 (JIS) aluminum alloy extruded shape (thickness 3 mm, width 50 mm, height 50 mm, length 200 mm) is used as the object to be processed. An extruded profile with a T-shaped cross section was used. Subsequent processing steps were performed in the order of the steps (b) to (h) described above in all the examples.

  In the masking ink application / drying step of step (c), a commercially available masking ink (340C, Brown, Yoshikawa Kako Co., Ltd.) was used. After screen printing, hot air drying was performed to print a character-shaped pattern. The masking printing film thickness was 10 μm. In the (g) masking removal step, the masking film was removed with an enamel thinner.

  (D) The film removal treatment in the etching process is a sodium hydroxide solution (100 g / L, 50 ° C.), the etching treatment is ferric chloride (42 ° Be, Toagosei Co., Ltd.), and the alkali etching treatment is a sodium hydroxide solution. (100 g / L, 50 ° C.) In the smut removing step, each was treated with nitric acid (150 g / L).

  (E) A blast process is a process performed in order to make the recessed part formed in the above-mentioned etching process into a fine uneven | corrugated shape, and processed using the bead blast apparatus (Fuji Seisakusho Co., Ltd.). As the blasting conditions, the objective is to finish the surface into a fine concavo-convex shape, so that glass beads having a diameter of about 80 μm are projected onto the processing surface at an air pressure of 0.05 MPa.

  In both steps (f) and (h), a 200 g / L sulfuric acid bath is used, and a carbon electrode plate is used as the counter electrode. The sulfuric acid bath temperature is 20 ° C. and the voltage is 12 V, and the anodized film becomes 6 μm. Anodizing treatment was performed as described above. Moreover, in the anodizing process of the step (f), normal silver anodizing was performed, and in the anodizing process of the step (h), dark colored anodizing by a secondary electrolytic coloring method was performed.

  In the pretreatment (degreasing step) of the step (b), in Example 1, a treatment liquid to which zircon hydrofluoric acid (zircon hydrofluoric acid) in an amount of 0.1 g / L was added as fluorine was used. In Example 2, 0.1 g / L of titanium hydrofluoric acid (titanium hydrofluoric acid) was added as fluorine, and in Example 3, 0.1 g / L of ammonium fluorinated zirconate (zircon ammonium fluoride) was added as fluorine. The treated liquid was used. Moreover, nitric acid 0.1g / L was added to each process liquid, and it used as the 2nd washing water of a degreasing process. The treatment method was immersion, the liquid temperature was 45 ° C., and the treatment time was 1.5 minutes. Example 4 uses the same treatment liquid as in Example 1 and uses warm water in a hot water drying process for draining and drying in the degreasing process. The treatment method is immersion, the liquid temperature is 80 ° C., and the treatment time is 1.0. Minutes.

  In Examples 1 to 4, the masking ink applied in step (c) can be performed up to (h) alumite step without peeling off in (d) etching step or (e) blasting step. It was possible to obtain a finished appearance sufficient as a product without breaking the parting line of the masking part.

  On the other hand, in Comparative Example 1, an aluminum alloy was treated in the same manner as in Example 1 except that no complex fluoride was added in Example 1. In Comparative Example 2, an aluminum alloy was treated in the same manner as in Example 1 except that nitric acid was not added in Example 1. In Comparative Example 3, an aluminum alloy was processed in the same manner as in Example 1 except that the concentration of complex fluoride in Example 1 was changed and the concentration of zircon hydrofluoric acid was changed to 20 g / L as fluorine.

  As a result of the treatment, in Comparative Examples 1 to 3, the masking ink applied in the step (c) was peeled off in the (d) etching step and the (e) blasting step. In particular, in Comparative Example 3, after removing the masking in the step (g), looking at the color tone of the masked part, the color tone is uneven and turbid, and the value as the appearance of the product Became faded.

It is a figure which shows the process process of one Embodiment of this invention.

Claims (3)

In a surface treatment method for forming a pattern on a surface of an aluminum alloy by forming a predetermined pattern by applying a masking ink to the surface of the aluminum alloy, performing the post-process using the pattern as a mask, and then removing the masking ink to form a pattern on the surface of the aluminum alloy. ,
Before the step of depositing said masking ink, look including the 0.05 to 10 g / L of the amount of complex fluoride and nitrate 0.001 to 5 g / L as fluorine, be washed with a liquid that does not contain sulfuric acid A surface treatment method for an aluminum alloy having excellent adhesion characteristics with a masking ink.   2. The adhesion property with the masking ink according to claim 1, wherein the complex fluoride is one or more selected from the group consisting of zircon hydrofluoric acid, titanium hydrofluoric acid, and zircon ammonium fluoride. Excellent surface treatment method for aluminum alloy. The rear step state, and are etching treatment and blast treatment, the in etching or blast treatment masking ink is processed without being peeled off, the Rukoto parting portion is smoothly finish without parting line of the pattern is broken The surface treatment method of the aluminum alloy excellent in the adhesive characteristic with the masking ink of Claim 1 characterized by the above-mentioned.

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