Method for manufacturing a decorated aluminum base material and a decorated aluminum base material

Abstract

A laser decoration method for forming a coating film layer on the surface of a metal base material and irradiating a laser beam LB onto the coating film layer to apply a decoration, wherein a highly visible decoration can be achieved by performing effective coloring at a decoration site by a simple step while avoiding complex steps. The invention addresses the problem through a decorated aluminum base material production method characterized by comprising a step of forming a coating film layer on the surface of an aluminum base material, a step of irradiating a laser beam to partially expose the surface of the aluminum base material, and a step of performing an oxide coating forming process on the exposed surface of the aluminum base material, and forming a colored oxide coat on the exposed surface of the aluminum base material with the oxide coating forming process.

Description

Technical Field

[0001] The present invention relates to an aluminum base material including cans and the like.

Background Art

[0002] For a metal base material having a coating film formed on its surface, performing decoration such as marking by irradiating laser light is being carried out on various products. As one of the conventional techniques, there is known a technique of performing marking by removing a thick film to a depth that does not reach the surface of the metal base material when laser light is irradiated, with the film formed on the surface of the metal base material being a thick film (see Patent Document 1 below).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] According to the above-described conventional technique, when the coating film on the surface of the metal base material is a single layer, a part of the single layer can be shaved by laser light to form grooves, enabling decoration such as letters. However, since it is difficult to create a color difference between the decorated part and the non-decorated part, there is a problem that it is difficult to perform decoration with high visibility. In contrast, by making the coating film into two layers and making the colors of the first layer and the second layer different, it is possible to perform decoration with different colors. However, there is a problem that the coating film process becomes complicated by making the coating film into two layers.

[0005] An object of the present invention is to address such problems. That is, in a laser decoration method of forming a coating film layer on the surface of a metal base material and irradiating the coating film layer with laser light to perform decoration, an object of the present invention is to enable decoration with high visibility while omitting complicated processes by effectively coloring the decoration part in a simple process.

Means for Solving the Problems

[0006] In order to solve such problems, the present invention comprises the following configuration. A step of forming a coating film layer on the surface of an aluminum substrate; A step of partially exposing the surface of the aluminum substrate by irradiation with laser light; On the exposed surface of the aluminum substrate in treated water containing one or more metal ions selected from silicon, potassium, magnesium, calcium, iron, and zinc There is a step of performing an oxide film formation treatment, A method for manufacturing a decorated aluminum substrate, characterized in that a colored oxide film is formed on the exposed surface of the aluminum substrate by the oxide film formation treatment.

[0007] Furthermore, in another aspect, an aluminum substrate and a coating film layer are provided. The aluminum substrate has the coating film layer formed on its surface. The coating film layer has a portion where the coating film layer is removed, and that portion containing one or more metals selected from silicon, potassium, magnesium, calcium, iron, and zinc Is a colored oxide film, thereby solving the problem.

Effects of the Invention

[0008] According to the method for manufacturing an aluminum substrate of the present invention having such characteristics, in a laser decoration method in which a coating film layer is formed on the surface of a metal substrate and the coating film layer is irradiated with laser light for decoration, effective coloring can be applied to the decorated portion in a simple process, and high-visibility decoration can be obtained while omitting complicated processes.

[0009] Also, according to the present invention of the container Equipment, using a new decoration principle the container Device the material Can be provided.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Mode for Carrying Out the Invention

[0011] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The laser decoration method according to the embodiment of the present invention is for performing laser decoration on a device L as shown in FIG. 1 the container The device L is one on which a coating layer L3 is formed via an appropriate surface treatment layer L2 on an aluminum base material L1. In this way the container The device L forms a can container filled with food such as beverages, or an aerosol can filled with liquid materials for daily life and household use, etc. such a container ​

[0012] In this way such a container For the equipment L, decorations such as characters and patterns are applied to the coating layer L3. However, decorations related to the individual information of the product are applied after the can is formed. Therefore, laser decoration is performed so that the decoration can be carried out without deforming the can.

[0013] As shown in Fig. 1(a), the laser decoration method according to the embodiment of the present invention such a container As shown in Fig. 1(b), the equipment L is irradiated with laser light LB to remove a part of the coating layer L3 (and the surface treatment layer L2), and the surface of the aluminum base material L1 is partially exposed. Then, as shown in Fig. 1(c), by performing an anodizing treatment using treatment water TW on the exposed aluminum base material L1 (surface exposed portion L11), as shown in Fig. 1(d), a colored anodic film is formed on the exposed aluminum base material L1. The color here is a color with a lower lightness than the color of the aluminum base material L1, for example, colors such as black, brown, and gray.

[0014] At this time, it is preferable to select the material, film thickness, etc. of the coating layer L3 such that the aluminum base material L1 is effectively exposed by the irradiation of the laser light LB. It is preferable to select a color of the coating layer L3 that has a high contrast with the colored anodic film formed on the decorated portion.

[0015] In particular, when performing decoration by irradiating the coating layer L3 with laser light LB, by appropriately selecting the wavelength and output of the laser light LB for the color of the coating layer L3, the laser light LB can easily reach the lower layer of the coating layer L3, remove the surface treatment layer L2, and effectively expose the surface of the aluminum base material L1. When using a fiber laser with a wavelength of about 1000 nm as the laser light LB, the surface of the aluminum base material L1 can be effectively exposed with colors other than black and transparent colors.

[0016] When performing the oxide film forming treatment, the treatment water TW used is one containing active ingredients for forming a colored oxide film. Since it has been found that silicon, potassium, magnesium, calcium, iron, and zinc can form a colored oxide film, examples of the active ingredients include metal ions such as silicon, potassium, magnesium, calcium, iron, and zinc, and it is preferable that it contains one or more of these components. In particular, silicon can be cited as a component that easily forms a black oxide film.

[0017] Also, since heating the treatment water TW can accelerate the oxidation reaction, it is preferable to use hot water at 50°C or higher, preferably 70°C or higher, and more preferably 80°C or higher. Further, it is preferable that the treatment water TW has a pH of 6.5 or higher in order to accelerate the oxidation reaction.

[0018] the container When the equipment L is a material for a food container, after forming the container, a hot water sterilization step (for example, retort sterilization) and a cooling step are performed. In this case, water obtained by heating tap water or groundwater is often used. Since tap water and groundwater generally contain silicon, the hot water sterilization step of the food container can also serve as an oxide film forming treatment for decoration. Also, for aerosol containers, warm water inspection is performed, and since water at about 40 to 60°C of tap water or groundwater is often used at this time, the warm water inspection of the aerosol container can also serve as an oxide film forming treatment for decoration.

[0019] As can be understood from the above principle, the aluminum base material of the present invention includes any material as long as aluminum or an aluminum alloy is partially exposed on its surface and a coating film layer can be formed. Also, even if it is a laminate of a metal different from aluminum, if the surface is aluminum on which a coating film layer can be formed, it is included in the "aluminum base material" of the present invention. Further, the aluminum base material may be processed into a can or the like, or may be in a plate shape, and the shape and the degree of processing are not limited. Also, the material of the coating film layer may be anything, and the coating means for forming the coating film layer is not limited.

[0020] (Experiment 1) Experiment 1 is an experiment to examine the effects of substances contained in the treated water TW. [Pretreatment of Samples] An aluminum substrate L formed with a surface treatment layer L2 by performing chromate phosphate treatment (CP treatment) 1 was prepared into a plate. On the surface treatment layer L2 of the plate, a red paint was applied to form a coating film layer L3. for Subsequently, the plate was laser-decorated using a laser beam LB (fiber laser beam with a wavelength of 1064 nm) to form a star-shaped pattern. As a result, a plurality of star-shaped decoration regions were formed on the surface of the plate. In the star-shaped decoration regions, the coating film layer L L3 disappeared, and the surface of the aluminum substrate L1 was exposed, becoming a surface exposed portion L11. A plurality of samples subjected to such pretreatment were prepared.

[0021] [Treated Water] In Experiment 1, treated waters 1 to 3 were prepared as the treated water TW. Treated water 1: Pure water (pH 5.6) Treated water 2: Commercially available mineral water A (pH 6.9) Treated water 3: Commercially available mineral water B (pH 7.5) Note that since pure water contains no ions, it has almost no electrical conductivity and is a liquid for which pH measurement is difficult in the first place. It is known that pure water takes in carbon dioxide gas in the air and the like, and after being in contact with air for a sufficient time, the pH becomes about 5.6. The pH measured with pure water is shown for reference.

[0022] [Conditions for the Oxide Film Formation Process] The three types of treated water were placed in separate beakers. Then, the samples were immersed in the treated water. The openings of the beakers were covered with aluminum foil. The conditions for the oxide film formation process were carried out using an autoclave at 125°C for 30 minutes to promote oxidation.

[0023] [Results of Experiment 1] Figure 2 shows photographs of samples showing the results of Experiment 1. Figure 2(a) is a photograph of the sample before the oxide film formation step, that is, before the oxide film L4 is formed. This is shown as a control experiment. Figure 2(b) is a photograph of the sample after the oxide film formation process using treated water 1 (pure water). When treated water 1 (pure water) was used, there was almost no change in the color of the oxide film L4 compared to the sample before the oxide film formation process, and a colorless oxide film L4 was formed. Figure 2(c) is a photograph of the sample after the oxide film formation process using treated water 2 (commercially available mineral water A (pH 6.9)), and Figure 2(d) is a photograph of the sample after the oxide film formation process using treated water 3 (commercially available mineral water B (pH 7.5)). In both the experiments using treated water 2 and treated water 3, it was found that a black oxide film L4 had been formed, as compared to before the oxide film formation process. It was found that even with the amount of substance contained in mineral water, the exposed surface portion L11 of the aluminum base material L1 becomes a colored oxide film L4 through the oxide film forming process.

[0024] (Experiment 2) The following treated water 4 was prepared and an experiment was carried out. Treated water 4: A buffer solution of pH 7.1 prepared by adding disodium hydrogen phosphate and sodium dihydrogen phosphate

[0025] [Results of Experiment 2] Figure 3 shows photographs of the samples showing the results of Experiment 2. Figure 3(a) shows a photograph of the sample before the oxide film formation process, and Figure 3(b) shows a photograph of the sample after the oxide film formation process using treatment water 1 (pure water). Both Figure 3(a) and Figure 3(b) are presented as controls. FIG. 3(c) is a photograph of the sample after the oxide film formation process using treatment water 4 (buffer solution of pH 7.1), and it can be seen that the sample has turned slightly darker in color compared to the control. Since a discoloration was observed at pH 7.1, it was estimated that a discoloration would occur at a pH of 6.5 or higher, taking into account the results of Experiment 1 as well.

[0026] (Experiment 3) Experiment 3 aims to examine the relationship between the iron concentration and the discoloration of the oxide film L4. The conditions of the oxide film formation process were the same as those in Experiment 1. Treated water 5: Industrial water with an iron concentration of 0.3 ppm Treated water 6: Industrial water with an iron concentration of less than 0.1 ppm

[0027] [Results of Experiment 3] Figure 4 is a photograph of the sample showing the results of Experiment 3. Figure 4(a) is the sample before the oxide film formation process, and Figure 4(b) is the sample after the oxide film formation process using treated water 1 (pure water). Both Figure 4(a) and Figure 4(b) are presented as controls. Figure 4(c) is a photograph of the sample after the oxide film formation process using treated water 5 (industrial water with an iron concentration of 0.3 ppm), and it can be seen that the degree of discoloration of the oxide film L4 is large and it has turned black. Figure 4(d) is a photograph of the sample after the oxide film formation process using treated water 6 (industrial water with an iron concentration of less than 0.1 ppm), and although not as much as in Figure 4(c), it can be seen that it has turned black. From this Experiment 3, it was found that the higher the iron concentration, the greater the degree of discoloration of the oxide film L4 and it turns black.

[0028] (Experiment 4) Experiment 4 aims to examine the relationship between the silicon concentration and the discoloration of the oxide film L4. The conditions of the oxide film formation process were the same as those in Experiment 1. Excess silicon dioxide powder was added to pure water and stirred, and then autoclaved at 125 °C for 60 minutes. After that, the undissolved silicon dioxide powder was removed by filtration to prepare silicon-containing water. This silicon-containing water was diluted with pure water to prepare treated water TW with the following concentrations. The pH was adjusted to 7.5 by adding sodium bicarbonate. Treated water 7: Prepared water with a silicon concentration of less than 1 ppm Treated water 8: Prepared water with a silicon concentration of 2 ppm Treated water 9: Prepared water with a silicon concentration of 4 ppm Treated water 10: Prepared water with a silicon concentration of 24 ppm

[0029] [Results of Experiment 4] Figure 5 is a photograph of the sample showing the results of Experiment 4. Figure 5(a) is a photograph of the sample before the oxide film formation process, and Figure 5(b) is the sample after the oxide film formation process using Treatment Water 1 (pure water). Both Figure 5(a) and Figure 5(b) are presented as controls. Figure 5(c) is a photograph of the sample after the oxide film formation process using Treatment Water 7 (silicon concentration less than 1 ppm), and it can be seen that the degree of discoloration of the oxide film L4 hardly changes compared to the control. Figure 5(d) is a photograph of the sample after the oxide film formation process using Treatment Water 8 (silicon concentration 2 ppm), and the oxide film L4 is slightly blackened compared to the control. Figure 5(e) is a photograph of the sample after the oxide film formation process using Treatment Water 9 (silicon concentration 4 ppm), and it can be seen that the oxide film L4 is clearly blackened compared to the control. Figure 5(f) is a photograph of the sample after the oxide film formation process using Treatment Water 10 (silicon concentration 24 ppm), and it can be seen that the oxide film L4 is considerably blackened compared to the control.

[0030] (Degree of decoration) In the above Experiments 1 to 4, the oxide film L4 has been discolored and decorated by changing various conditions. Among them, there are those with a weak degree of discoloration of the oxide film L4 (such as Figure 5(d)). However, the oxide film L4 can also be used as one with a deliberately weak degree of discoloration. For example, it can be used when printing information that is not necessary for consumers. Printing unnecessary information prominently will result in a loss of design characteristics. the can This is advantageous when printing information that is not necessary for consumers, such as lot numbers, on the lid of the [object] and the like. Also, "decoration (printing)" includes not only characters but also patterns, designs, barcodes, two-dimensional codes, machine-readable information, etc. Also, it does not matter for what purpose the decoration (printing) is used.

[0031] (Temperature) In the experiment, as the conditions for the oxide film formation process, an autoclave was used and the process was carried out at 125°C for 30 minutes. These conditions were set to promote the oxide film formation reaction and to examine the influence of the hot water sterilization process (e.g., retort sterilization).

[0032] (Experiment 5) An experiment was conducted to examine the relationship between temperature and time until a colored oxide film L4 with sufficient visibility was formed. The color difference of the printed part was measured using a flexographic printing spectrophotometer eXact. As a control experiment, based on the L of the oxide film L4 that had not changed color to a colored state before the heat treatment * the L after the heat treatment * was measured, and the decrease value of L * was evaluated. Laser light LB (fiber laser light with a wavelength of 1064 nm) was used for engraving. The aluminum plate on which engraving was performed was immersed in each treatment water and heated in a constant temperature bath.

[0033] [Results of Experiment 5]

Table 1

[0034] It was found that when the temperature reached 70°C or higher, the degree of discoloration was clearly greater and the speed of discoloration also became faster.

[0035] In addition, in the examples, although means using laser light LB were used to increase the efficiency in removing the coating layer L3, any means can be used even if the efficiency is inferior as long as the coating layer L3 can be removed and the surface exposed part L11 can be created.

[0036] As described above, the laser decoration method according to the embodiment of the present invention can perform laser decoration with high contrast and high visibility by coloring the decorated portion black or the like without performing a time-consuming coloring process. The laser decoration method according to the embodiment of the present invention can efficiently perform decoration with good visibility by combining the oxide film forming treatment with the hot water sterilization process in a container that requires sterilization, such as a can filled with food. Also, in an aerosol can, efficient decoration with high visibility can be performed by combining the oxide film forming treatment with the warm water inspection process.

Explanation of Reference Numerals

[0037] L : the container Equipment, L1: Aluminum substrate, L11: Surface exposed portion, L2: Surface treatment layer, L3: Coating film layer, L4: Oxide film, LB: Laser beam, TW: Treatment water

Claims

1. A step of forming a coating film layer on the surface of an aluminum substrate; A step of partially exposing the surface of the aluminum substrate by irradiation with laser light; A step of performing an oxide film formation treatment on the exposed surface of the aluminum substrate in treated water containing one or more metal ions selected from silicon, potassium, magnesium, calcium, iron, and zinc; A method for manufacturing a decorated aluminum substrate, characterized in that a colored oxide film is formed on the exposed surface of the aluminum substrate by the oxide film formation treatment.

2. The method for manufacturing a decorated aluminum substrate according to claim 1, wherein the color of the oxide film is a color having a lower lightness than the color of the aluminum substrate.

3. The method for manufacturing a decorated aluminum substrate according to claim 1, wherein the treated water has a pH of 6.5 or higher.

4. The method for manufacturing a decorated aluminum substrate according to claim 1 or 3, wherein the temperature of the treated water is 50°C or higher.

5. The aluminum substrate is a can, The method for manufacturing a decorated can according to any one of claims 1 to 4, wherein the oxide film formation treatment also serves as a hot water sterilization step of the can.

6. The aluminum substrate is an aerosol container, The method for manufacturing a decorated aerosol container according to any one of claims 1 to 4, wherein the oxide film formation treatment also serves as a warm water inspection of the aerosol container.

7. An aluminum substrate and a coating film layer are provided, The aluminum substrate has the coating film layer formed on its surface, The coating layer has a portion where the coating layer has been removed, and the portion is a colored oxide film containing one or more metals selected from silicon, potassium, magnesium, calcium, iron, and zinc. The container material is characterized by this.

8. The container material according to claim 7, wherein the container material is a lid of a can.

9. The container material according to claim 7, wherein the container material is a body of a can.

10. The container material according to claim 7, wherein the container material is a body of an aerosol container.

11. A container filled with a content, using the container material according to any one of claims 7 to 10.

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