KR800000670B1 - Aluminium and aluminium alloy anodizing method - Google Patents

Abstract

A method of forming an oxide film on the surface of an aluminum material by anodizing the aluminum material in an aqueous solution containing 0.5 to 10 % by weight of oxalic acid and 0.05 to 1.0 % by weight of sulfuric acid, in which either an electrolyzing voltage or the temperature of the aqueous solution is controlled in the range of 5 to 150v or 0 to 40≰C, whereby the oxide film is colored in color tone from bronze to silver.

Description

Method of forming oxide film of aluminum or aluminum alloy

1 is a graph showing the relationship between the voltage and the aqueous solution temperature and the color tone of the oxide film in the context of the present invention.

2 is a graph showing the relationship between the voltage and the aqueous solution temperature and the current density in the context of the present invention.

3 is a graph showing the relationship between voltage, dissolved aluminum ions, and current density in the context of the present invention, and 2-2, 2a-2a, 3-3, and 3a-3a in FIG.度 線).

This invention is an anodized aluminum material in an aqueous solution of oxalic acid containing sulfuric acid in the method of producing an oxide of aluminum or an aluminum alloy (hereinafter referred to as an aluminum material), and from bronze to silver white (Silver). The present invention relates to a method for producing a colored oxide film having a wide range of color tones.

In general, aluminum materials are lighter than other metal materials and have excellent workability. Therefore, aluminum materials are used for various purposes, and in particular, they are used for building materials. The aluminum surface used for building materials is supplied to the market by anodizing, etc. Recently, the aluminum material surface-treated by anodizing has been colored during anodization. It is now available in the market as aluminum material.

However, the aluminum material, which is supplied to the market as a color aluminum material, still has various problems in the coloring method and also has a narrow color gamut.

That is, (a) aquatic aqueous solution method and (b) aromatic sulfonic acid aqueous solution method are known conventionally as a coloring method of an aluminum material. The aquatic acid solution method of (A) refers to a method of producing a yellow colored pigmented oxide film by anodizing an aluminum material in an aqueous solution containing aquatic acid. This coloring method is very excellent because it is easy to obtain the basic fisheries, is cheap, and the electrolytic conditions are industrially suitable.However, the range of colorable hues is limited to the yellow system especially obtained in yellow. There is a flaw.

In addition, the coloring method of (b) refers to a method for producing a bronze colored oxide film by anodizing in the aqueous solution containing aromatic sulfonic acid as in the coloring method of (a). Unlike the method of (a), this method has a very wide range of coloration and coloration in bronze, but the cost of the aromatic sulfonic acid, which is a basic liquid, is extremely expensive, and furthermore, a relatively large amount of defects are required.

In order to solve the above-mentioned drawbacks, the present invention provides a colored oxide film by anodic oxidation of an aluminum material, among which a small amount of sulfuric acid is added to an aqueous solution based on aquatic acid. In particular, it is an object of the present invention to provide a method for producing a colored oxide film from bronze to silver white by adjusting the voltage, dissolved aluminum ion amount and temperature of an aqueous solution.

In addition, conventionally, a method for producing an anodized aluminum material in an aqueous solution containing a small amount of sulfuric acid to produce a bronze colored oxide film is Japanese Patent Application Nos. 46-83,336, 46-83,337, 46 -83,338, 47-52,528 and 47-66,624, respectively, and the specifications of Japanese Patent Application No. 47-52,528 describe oxidation in aqueous solutions containing dissolved aluminum in addition to hydroxyl and small amounts of sulfuric acid. Although treatment methods are also described, these coloring methods only provide bronze to amber colored oxide coatings, but they are not colorless, close to silver white or any other colored oxide coatings. To get it, you have to use another method.

On the other hand, the present invention can produce a color tinted oxide film of a wide range of colors from bronze to silver white as desired despite the anodizing treatment in an aqueous solution containing aquatic acid and a small amount of sulfuric acid.

Hereinafter will be described in order from the aqueous solution composition (水溶液 組成) for this invention as follows.

(1) aqueous solution composition

(a) 0.5-10% by weight of fisheries (hereinafter referred to as% by weight)

Fisheries contribute to the production of an oxide film on the aluminum material by anodization, as well known. In this invention, an aqueous solution added with hydroxide is used as an electrolytic base solution.

However, in the present invention, in addition to the purpose of forming the oxide film, the chemical structure of the fishery is used to contribute as a coloring source, and at the same time, the contribution sun as the coloring source is related to the electrolytic voltage. The amount is added or subtracted according to the difference.

In other words, the oxide film produced by the anodizing treatment is incompletely bonded to AlO. The spinel type lattice structure (Spinel type 格子 構造), such as Al ₂ O ₃ , will cause excessive bonding. Therefore, there will be room for inclusion by invading other molecules in the oxide film that is unreasonable. It is presumed that the oxide film is colored when the striking person has a qualification to be a coloring source.

In addition, the spinel-type lattice structure that is unreasonable to the bond will have a safe structure by being completely bonded by incorporating other molecules as the coloring source.

In view of this, the present inventors have studied the molecules that can be used as color sources, and it has been found that hydroxyls become color sources when coexisted with sulfuric acid described below. That is, it was confirmed that carboxyl group (-COOH) was decomposed and polymerized in fishery to form a chromophore.

In addition to determining the concentration of aquatic acid that can achieve this purpose by considering only the oxide film formation or the color itself, it is also necessary to carefully determine the coloration of the fish in consideration of the electrolytic conditions. Will be. In more detail, if the aqueous solution does not contain at least 0.5% of hydroxyl, the coloring effect of the oxide film is insufficient as described in the following electrolytic conditions, so that simply changing the electrolytic conditions cannot change the color tone. In addition, the electrolytic coating is insufficiently formed, resulting in poor electrical conductivity, resulting in electrocution in the coating, and when 10% or more of the acid is contained, problems in dissolving in water (not easily dissolved) and color deteriorate. do.

For this reason, the range of 2.5-2.7% is illustrated when the composition ratio is the best when the composition range of the aqueous solution of the above-mentioned aqueous solution is determined.

(b) sulfuric acid (lactic acid = lactic acid) 0.05-1.0%

Sulfuric acid has an effect of improving the current carrying property of the aqueous solution to some extent according to the addition thereof, but in the present invention, as described in (a), the ratio of sulfuric acid and the sulfonic acid group of sulfuric acid and sulfuric acid in the oxide film ( By infiltrating -SO ₃ H), the color tone can be changed as desired by appropriately changing the proportion of the mass production group.

On this point, the inventors of the present invention have specifically studied the relationship between dissolved aluminum ions and their coloring mechanisms (mechanisms), that is, the results were as follows.

As the amount of dissolved aluminum ions increased, the current carrying property of the aqueous solution decreased, thereby making the thickness of the oxide film thinner.

Therefore, since the oxide film having the desired corrosion resistance and mechanical strength is required to have a certain thickness, it is possible to apply a high voltage in accordance with the increase in the amount of dissolved aluminum ions. In addition, as described below, when the voltage is changed, especially when the voltage is increased, the color tone of the oxide film is changed from silver white to bronze, so that the desired color tone can be obtained by adjusting the amount of dissolved aluminum ion and voltage.

This phenomenon is more pronounced when the amount of dissolved aluminum ions is small. For example, a predetermined current density can be obtained even by a low voltage, so that an oxide film having a desired thickness is easily produced, but no color is colored. This is because the decomposition factor of the color factor described above does not occur, and thus, the color factor infiltration into the oxide film does not occur. In this case, too, it is impossible to apply a high voltage, and even if an excessively high voltage is applied, the original purpose of the aluminum chemical conversion treatment is lost because the film is destroyed rather than the oxide film is colored. In this way, by coating a stable aluminum oxide on the aluminum surface it will not be able to play a role of protecting the surface of the aluminum material.

In other words, the owner of the oxide film is the carboxyl group (-COOH) as described above, and the oxide film is developed even by invasion of the carboxyl group alone, but the sulfonic acid group as a denial to the owner. When (-SO ₃ H) invades, it is possible to obtain a wide range of shades from bronze (bronze) to silver white (silver) according to their ratio.

Therefore, in this invention, the upper limit of sulfuric acid addition is limited to 1.0% and the lower limit is set to 0.05% in consideration of such a point. Therefore, if the upper limit is exceeded, there is a risk of burning phenomenon. It won't work.

In other words, when the amount of sulfuric acid added exceeds the upper limit of 1.0%, due to the chemical nature of the conversion, it is chemically oxidized with the aluminum element or the alloy element of aluminum or aluminum alloy to make the corrosive substance of lactate, and thus decomposition decomposition to the sulfonic acid group as a coloring source. It causes difficulties, but rather results in greatly inhibiting the formation of the aluminum oxide film by the fish.

For this reason, the optimum range of sulfuric acid addition is preferably 0.14-0.17% in consideration of the relationship with the optimum range of fisheries.

(2) dissolved aluminum ion amount of 0.05-6.0 g / L.

Since dissolved aluminum ions also play a role as an adjustment factor of the color tone of the oxide film together with the electrolytic conditions as described below, in the present invention, this is added as one of the features.

47-52,528호의 명세서에 기재된 것을 보면 수용액중의 용존알미늄이온이 과전류(過電流)를 방지하는 역할 외에 어느정도는 착색에도 기여하고 있다고 하였으나 그 명세서에는 용존알미늄이온의 착색에 대한 기여기구(機構:mechanism)가 어떤것인가에 대해 기재가 되어있지 않으며 또한 해명도 없다. 또 용존알미늄이온량과 착색기구와의 관계가 상기와 같음에 대하여 이 발명에서는 전해조건들 중에서 특히 전압의 변화에 따라 산화피막의 색조를 원하는대로 변화시키는 것에 큰 특징을 갖고 있다.For example, Japanese patent application

47-52,528 discloses that dissolved aluminum ions in aqueous solution contribute to coloring to some extent in addition to preventing overcurrent. ) Is not written about, and there is no explanation. In addition, while the relationship between the amount of dissolved aluminum ions and the coloring mechanism is as described above, the present invention has a great feature of changing the color tone of the oxide film as desired according to the change of voltage among electrolytic conditions.

47-52,528호 기재의 경우에는 산화피막의 착색을 달성할려면 어느정도의 전압을 필요로 하는데 이로 인해-산화피막의 파괴는 차치하고-전류밀도가 증가하게 되어 전기에너지 경제상으로도 바람직하지 못하다. 그러나 이 발명에서는 적절한 용존알미늄이온량 범위내에 있게 하기 위해 고전압하에서도 저전류전해가 이루어질 수 있는 바이점이 이 발명의 또 하나의 특징이다.And that is

In the case of 47-52,528, the coloring of the oxide film requires a certain voltage, which is why the destruction of the oxide film, apart from the destruction of the oxide film, increases the current density, which is undesirable in terms of electrical energy economy. However, in this invention, a bi-point which enables low current electrolysis even under high voltage in order to be within a suitable dissolved aluminum ion range is another feature of this invention.

In order to achieve a high effect with the amount of dissolved aluminium having the above effects, the dissolved aluminum amount is preferably 0.05-6.0 g / L in consideration of the electrical conductivity and the relationship with the voltage, among the properties of the aqueous solution composition. When less than l, the effect, especially the color development is lost, and when more than 6.0 g / l, the electrical conductivity of the aqueous solution is bad, causing electrolysis.

(3) electrolytic conditions

(a) Voltage 5-150V

Voltage is one of the most important adjustment factors in this invention and is an essential component of this invention.

In this invention, by changing the voltage in relation to the temperature of the aqueous solution having the composition as described above and the amount of dissolved aluminum ions, thereby producing an oxide film of a desired color ranging from silver white to bronze. In other words, the coloring mechanism of the present invention, that is, the coloring mechanism of the oxide film, decomposes the hydroxyl and sulfuric acid contained in the aqueous solution as described above, and the colored factor generated from the decomposition penetrates and binds to the oxide film, thereby forming various color oxide films. It is a mechanism for generating At this time, it is voltage that decomposes the coloring factors and supplies energy that invades and binds to the oxide film. In other words, the voltage at the time of electrolysis causes predetermined electrolysis, and at the same time, decomposes and generates the coloring factor, and serves to induce the generated color factor by invading the oxidative coating.

However, although the voltage has such a purpose, the degree of contribution to the purpose is not necessarily linearly proportional. At this time, the degree of contribution of the voltage depends on other conditions, such as the temperature of the aqueous solution, the amount of dissolved aluminum ions, the amount of the aqueous solution, and the distance between the anodes.

In the present invention, the color tone of the oxide film is changed by changing the voltage in consideration of the relationship with the above manufacturing factor, but mainly the voltage and the aqueous solution temperature, only when the other factor of the voltage is within the following range except the above-mentioned amount of dissolved aluminum ion. Considering the relationship between the voltage and the amount of dissolved aluminum, it is also one of the characteristics of the present invention that the change of the voltage can produce an oxide film having various color tones as desired.

In other words, the coloring factors are carboxyl and sulfonic acid groups, and these factors are generated from the decomposition of fish and sulfuric acid. These factors require constant energy for the decomposition to proceed, or for the coloring factor to penetrate into the oxide film and bind to it and develop color development. When this energy is supplied, it is mainly a voltage, and the necessary constant voltage is the reference voltage. In this way, if the energy is not supplied at a voltage higher than or equal to the reference voltage during electrolysis, the oxide film may not be colored well, but a change in color tone due to the change of voltage is very remarkable within the voltage range higher than or equal to the reference voltage.

However, the actual decomposition, intrusion, and coupling of the reference voltages are not all of the supplied voltages, but the rest are consumed by other factors described above. As a result of the present inventors' studies, the composition of the aqueous solution and the amount of dissolved aluminum ions are described. Within the range, the color tone change of the oxide film was remarkable when the supply voltage was over 60V.

For example, Fig. 1 shows the relationship between the voltage and the aqueous solution temperature when the aluminum alloy A. A 6,030 is subjected to the color oxide film treatment according to the present invention.

Where A is bronze, B is amber, C is light amber, and D is silver white. In addition, bronze (A), amber (B), and soft amber (C) all belong to the I-I line, so that various colors can be easily colored only by changing the temperature of the aqueous solution under the condition of voltage of 60V. do.

In addition, in the region below the 60V voltage below the I-I line, the influence of the voltage on the colorability becomes low. If the voltage is lowered below 60V and the aqueous solution temperature is increased, silver white (D) that is almost achromatic can be easily obtained. It becomes possible. ,

In addition, the value of the I-I line may change depending on the composition of the aqueous solution and the conductance of the aluminum material, but in any case, there is always a corresponding voltage on the I-I line.

Note that the voltage actually takes into account the distance between the anodes and the amount of aqueous solution in the electrolytic cell.

It is desirable to determine the voltage at this time with reference to Table 1.

Thus, the proper value of the static pressure to be supplied should also be determined in consideration of the distance between the anodes and the amount of aqueous solution in the electrolytic cell. For example, the optimum value at the aqueous solution temperature of 10 ° C. and the average current density of 15 A / dm ² is shown in Table 1.

TABLE 1

As the distance between the anodes is increased, the electrical resistance of the aqueous solution is increased to increase the voltage, and if the amount of the aqueous solution is increased, the electrical resistance is increased to increase the voltage. Therefore, when the voltage needs to be increased, the color tone of the oxide film can be easily adjusted by appropriately adjusting the distance between the anodes. Will be.

That is, when the distance between the anodes and the amount of aqueous solution increases, the electrical resistance of the aqueous solution becomes high, and a high voltage needs to be applied. Therefore, in order to control the color tone of the oxide film, it is necessary to apply voltage in consideration of these phenomena.

And when the range of voltage that can have the above effect is 5-150V and less than 5V, the above effect cannot be obtained even if the conductivity of the aqueous solution is improved with other factors such as the temperature of the aqueous solution. Even if other conditions are adjusted, the desired effect is not obtained because the oxide film itself is destroyed.

(b) the temperature of the aqueous solution

The aqueous solution temperature has the same electrical conductivity as the aqueous solution becomes the electrolytic solution, and as the aqueous solution temperature increases, the electrical conductivity improves. Accordingly, the rate at which the rise of the aqueous solution temperature and the applied voltage serve as a reference voltage is shown in FIG. 1. As shown in FIG.

However, if only the aqueous solution temperature is raised to improve the electrical conductivity, agglomerates of the film are formed, and the properties thereof deteriorate. Therefore, the upper limit of the aqueous solution temperature is 40 ° C. In addition, the temperature of the aqueous solution can be lowered to the top as an adjustment factor, but lowering too much requires expensive cooling equipment, so the lower limit is 0 ° C.

In other words, as described above, the voltage and the aqueous solution temperature have a very close relationship, which will be described with reference to FIG. 2. Here, the 2-2 line represents an isocurrent density line of 2.5 A / dm ² and the 2a-2a line represents an isocurrent density line of 0.5 A / dm ² . The isocurrent density lines from 2.5 A / dm ² to 0.5 A / dm ^{2 are} then obtained.

Therefore, in the range of 0.5-2.5A / dm ² , if the current density is constant by decreasing the aqueous solution temperature while increasing the voltage or vice versa, an oxide film having various color tones can be obtained, and in particular, a method of keeping the current density low If you keep it low, you can save a lot of power.

(c) current density

The current density does not directly affect coloring but contributes to the formation of the oxide film. 0.5-5 A / dm ² is preferred in this respect. This invention has a feature that it can be colored in a low current region.

(D) electrolysis

There are various other electrolytic conditions, but the most important of these is the amount of dissolved aluminum ions as described above. The relationship between this and voltage is similar to that of FIG. 3, which is similar to that of FIG. Here, the 3-3 line represents an isocurrent density line of 2.5 A / dm ² , and the 3a-3a line is an isocurrent density line of 0.5 A / dm ² .

As shown in the figure, when the applied voltage V increases in the current density range of 0.5-2.5A / dm ² , the dissolved aluminum ion is increased to maintain the current density. Film can be produced, which greatly reduces power.

(4) Aluminum material

In the present invention, even if the aluminum material is changed, the colored oxide film is produced, and the color tone is slightly different at this time.

The reason for this is that the conductivity of the aluminum material is changed because the amount of alloy element and the type of alloy element are changed by the change of the material. As an example, the results of treatment of the aluminum material composed of various elements shown in Table 2 by this invention method are shown in Table 3.

TABLE 2

TABLE 3

As can be seen from Table 3, even if the material changes, according to the present invention, it is possible to color in tones ranging from bronze to amber.

An example will be described below.

Example 1

The electrolytic treatment of aluminum material A. A1100 in the aqueous solution of the composition as shown in Table 4 and the electrolytic conditions indicated therein produced various color tones and colored oxide films. The results are also shown in Table 4.

As a result, the oxide film having a color tone ranging from bronze to silver white was obtained by changing the transfer condition in the aqueous solution.

TABLE 4

Example 2

Using aluminum solution A.A1099, 1100, 5052, 6063 and 7074 as an electrolytic solution using an aqueous solution composed of 2.66% of fisheries, 0.152% of sulfuric acid, and 1.836 g / l of dissolved aluminum ions, three-phase electric wave current waves were used. Anodizing treatment was performed under the conditions of a direct current of 50 V and 30 minutes of energization. As a result, a colored oxide film as shown in Table 5 was formed.

TABLE 5

As described in detail above, the present invention focuses on the compositional characteristics of the aqueous solution in the aqueous solution containing hydroxyl and sulfuric acid, and adjusts the voltage appropriately while controlling the amount of dissolved aluminum ions and the temperature of the aqueous solution. It is about making tinted oxide film with color tones from silver to white as desired.

In addition, in the present invention, even in the aqueous solution having the same composition, it is possible to produce a colored oxide film having a desired color tone by simply changing the electrolytic conditions. Since low current density electrolysis is also possible, there is a significant saving of electrolytic energy, that is, electricity.

Claims (1)

As described above in the text, in an aqueous solution containing 0.5-10% by weight of oxalic acid, 0.05-1.0% by weight of sulfuric acid, and 0.05-6.0 g / l of dissolved aluminum ions, a condition of an aqueous solution temperature of 0-40 ° C at a voltage of 5-150V Changes the voltage when anodizing an aluminum or aluminum alloy at the same time, while adjusting the aqueous solution temperature under the given voltage, adjusting the dissolved aluminum ion amount, or simultaneously adjusting the aqueous solution temperature and the dissolved aluminum ion amount. A method of producing an oxide film of aluminum or aluminum alloy, characterized in that it produces a complex oxide film of a desired color from to white.

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