JPS6015718B2 - Surface treatment method for aluminum or aluminum alloy - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for surface treatment of aluminum or aluminum alloy, and more specifically, to anodizing the surface of these metals to form an anodic oxide film, and then treating the insides and surfaces of the fine pores of the film. The present invention relates to a surface treatment method for impregnating or adsorbing a barfluoroalkyl compound on a surface of the surface of the surface.

Generally, when the anodized film of aluminum or aluminum alloy is coated with a fluororesin, the metal surface or the oxide film surface becomes non-adhesive and slips easily, and this significantly reduces the coefficient of friction. ,
Significant improvements in wear resistance, water resistance, tread resistance, corrosion resistance, etc. can be expected.

That is, the utility value of metal articles using these aluminum or aluminum alloys can be significantly increased. Conventionally, in order to cope with the surface of the anodic oxide film or impregnate the fluororesin into the fine pores of the film, the methods of electrolytic fin deposition in a dispersion medium of fine powder of fluororesin, or the method of coating aluminum or aluminum alloy. A method has been proposed in which fine irregularities are first formed on a metal surface by a chemical or electrochemical method, then anodized, and a fluororesin is applied to this surface.

However, in the case of the above-mentioned electric Nagashiki electrodeposition, fine powder of fluororesin, which is a high molecular compound, is intended to be inserted into the micropores (inner pores, several tens to hundreds of amps) of the anodic oxide film. Unless the powder is smaller than the fine pores, it will not be possible to penetrate the powder sufficiently deep.

At present, it is only possible to coat the vicinity of the entrance of micropores or the surface of the film. Therefore, when the coating layer disappears due to wear or the like, the characteristics are naturally lost. If impregnated deep into the micropores, products with longer lifespans could be expected, but this is difficult with the current method of coating fine fluororesin powder by electropermanence.
On the other hand, if an uneven surface is first formed on the metal surface by a chemical or electrochemical method, the adhesion strength can be improved by the unevenness when applying fluororesin after anodizing treatment. In this case as well, the fluororesin is not sufficiently contained deep within the pores of the coating, and if the coating layer disappears due to wear etc., the properties will be lost and this will not provide a fundamental solution. The present invention has been made in view of the above-mentioned circumstances, and is made by impregnating or adsorbing a fluorinated hydrocarbon compound not only on the surface of the anodic oxide film but also deep into the micropores, thereby forming an oxide film. An object of the present invention is to provide a method for surface treatment of aluminum or aluminum alloy, which can maintain excellent properties until worn out.

The present invention is characterized in that after a porous anodic oxide film is formed on the surface of aluminum or an aluminum alloy, this is subjected to secondary electrolysis in an aqueous solution containing a barfluoroalkyl compound, and furthermore, this secondary electrolysis is 50 things
Heated water of o○ or more or 50qo containing the above compound
The purpose is to immerse it in the above aqueous solution.

It is inferred that the reason why the barfluoroalkyl compound is sufficiently impregnated and adsorbed and fixed in the micropores of the anodic oxide film by such a method is as follows.

That is, in the case of the present invention, since a barfluoroalkyl compound (30 carbon atoms or less), which is a fluorinated hydrocarbon compound with a relatively small molecular weight, is used, it can easily enter the micropores of the anodic oxide film, and it can be dissolved in an aqueous solution. As a result, secondary electrolysis can be carried out, so haze eternity, diffusion, etc. can be carried out effectively. Furthermore, since this compound has a gutter group, it is thought that a precipitation reaction or an adsorption reaction occurs in the micropores due to a change in hydrogen ion concentration, and the compound is fixed inside the micropores.
The bar-fluoroalkyl compound impregnated into the fine pores acts as a kind of anchor and adheres to the bar-fluoroalkyl compound layer on the film surface to ensure strong adsorption to the film surface. I will let you do it. Furthermore, the film thus treated is treated with heated water heated to 50°C or higher or 50◇ containing a barfluoroalkyl compound.
When diluted in an aqueous solution of 0 or more, the barfluoroalkyl compound is preferably fixed more firmly due to effects such as promotion of adsorption and pore-sealing effect. Note that the anodizing treatment in the present invention may be performed by a conventional method, and conditions that produce a porous anodic oxide film may be selected.

For example, electrolytes include sulfuric acid, post-acid, phosphoric acid, chromic acid,
An acidic solution such as sulfosalicylic acid or an alkaline solution containing caustic soda, sodium phosphate, etc. can be used. Alternatively, a fluorinated hydrocarbon compound may be dissolved in these electrolytic baths and incorporated into the anodic oxide film during formation of the anodic oxide film. Further, as the current waveform used, direct current, alternating current, AC/DC superimposed, AC/DC combined, incompletely rectified waveform, pulse waveform, rectangular wave, triangular wave, periodic waveform, etc. can be used. After completing the anodization treatment as described above, secondary electrolysis is then carried out in an aqueous solution containing a bar-fluoroalkyl compound, which has a relatively small molecular weight as mentioned above, that is, it has a carbon The number is preferably 30 or less or several,
In particular, those around 1 spacing are particularly preferred.

Specific examples of such barfluoroalkyl compounds include anionic compounds such as carboxylic acids, sulfonic acids, and phosphate esters, and cationic compounds such as ammonium salts. Of course, it is also good to use salt. More specifically, for example, barfluoroalkyl sulfonic acid ester, barfluoroalkylcarboxylic acid, barfluoroalkyltrimethylammonium, or salts thereof. In addition, these can also be used as a mixed aqueous solution. The concentration of these aqueous solutions varies depending on the type of the compound, but it is usually in the range of several IQ blood to several percent. Further, the temperature may normally be room temperature, but in the case of compounds with low solubility, the reaction may be carried out by flooding. Furthermore, if boric acid, ammonium borate, ammonium tartrate, ammonium phosphate, citric acid, or the like is added to the electrolytic solution, stable and uniform electrolysis can be performed. In addition, the current waveform during this secondary electrolysis should be such that, for example, in the case of an anion type, the current waveform is positive (anode), even if the treated substance is temporary or intermittent, and in the case of a cation type, it is negative (cathode). so that it becomes Further, the current density during electrolysis is, for example, in direct current electrolysis, from several mA/d to several tens of hA, preferably 10 hA/d or less. By the above secondary electrolytic treatment, the barfluoroalkyl compound is deeply impregnated into the fine pores of the anodic oxide film, and can also be sufficiently adhered to the surface.

Note that, before this secondary electrolytic treatment, dyeing with an organic dye, coloring treatment by electrolysis in an aqueous metal salt solution, or activation treatment by soaking in an aqueous solution of nitric acid or phosphoric acid may also be performed. Furthermore, the film that has undergone the secondary electrolytic treatment is subjected to a bonding treatment in heated water at 50°C or higher or an aqueous solution containing the above compound at 50°C or higher, if necessary.

This promotes adsorption and has a pore-sealing effect. Furthermore, a stronger compound film can be obtained by the polymerization reaction of the impregnated and adsorbed barfluoroalkyl compound. below,
Examples of the present invention will be described.

First, 61s aluminum plate (10 x 10 x 0.1 arc)
After degreasing, the sample was electrolyzed for 3 minutes at 3 A/d of DC in an electrolytic bath of 100.15 wt % per day 2S04 to produce a porous anodic oxide film.

Next, after washing with water, secondary electrolytic treatment was performed under the following conditions.

Example 1 In an aqueous solution of 0.5% bar fluoroalkyl carboxylate (Surflon S ll1, manufactured by Asahi Glass Co., Ltd.), a test piece was used as an anode and an aluminum plate was used as a counter electrode, and 50 mA'd was applied.
Constant current electrolysis was performed for 0 minutes.

Example (b) Electrolysis was carried out in an aqueous solution of 0.5% barfluoroalkyl phosphate ester (Surflon 112, manufactured by Asahi Glass Co., Ltd.) under the same conditions as in Example 1 above.

Example m Electrolysis was carried out under the same conditions as in Example 1 above in an aqueous solution of 1% barfluoroalkyl sulfonate (Megafac FIIO, manufactured by Dainippon Ink Co., Ltd.).

Example Using a W test piece as a cathode, 50 mA/d〆, 1
Constant current electrolysis was performed for 0 minutes.

--After the above secondary electrolytic treatment, the test piece was washed with water and dried, and the coefficient of static friction was measured by the tilt method (the mating material was copper, and the load was 2 nights).

Water bale antennae were also measured using a goniometer. The results were as shown in Table 1. For comparison,
The origin is also described. Table 1 Also, the test pieces of each of the above examples were operated in a taper type abrasion tester using copper as the roller material under a load of 1 kg for 1 hour, and the surface conditions were observed as follows.

In the comparative example of Origin, copper was baked and adhered to the test piece, and cracks were observed in the anodic oxide film.

In Examples 1 and m, a slight amount of copper seizure was observed, but no cracking was observed at all. In Example B, the copper was not baked at all in N. Furthermore, the test piece that had been subjected to the above secondary electrolytic treatment was placed in 90 to 10,000 heated water for 30 minutes.
A minute soaking process was carried out (Examples 1', 0', m', W').

In addition, each test piece was treated with a solution having the same composition as the secondary electrolyte.
5 to 9,500 for 3 minutes (Example 1'', B'', m'', W''). The friction coefficient and contact angle with water of each test piece treated with hot water and heated aqueous solution containing a barfluoroalkyl compound were as shown in Examples 1 to N before hot water treatment.
Almost no difference was observed. However, in the taper type wear test results, copper was slightly burned in the samples of Examples 1' and m' treated with hot water, but not at all in the samples of Examples 1'' to N'' treated with a heated bar fluoroalkyl compound aqueous solution. There was no burn-in of the copper. Furthermore, for the test pieces of each of the above examples, a vinyl tape (manufactured by Toyo Kagaku Co., Ltd., width 3) was pasted onto the test piece, and the peeling force in the 90° direction was measured. When this operation was repeated up to 100 times and the change in peeling force was observed, the results shown in Table 2 were obtained. As is clear from the explanations in Table 2 and above, according to the present invention, after forming a porous anodic oxide film on the surface of aluminum or aluminum alloy, this is subjected to secondary electrolysis in an aqueous solution containing a barfluoroalkyl compound, and then Because this secondary electrolyzed material is immersed in heated water at 50°C or higher or an aqueous solution at 50°C or higher in which a barfluoroalkyl compound is dissolved, the surface of the anodic oxide film is of course
The fluorinated hydrocarbon compound can be sufficiently impregnated or adsorbed deep into the micropores.

Claims (1)

[Scope of Claims] 1. An aluminum or aluminum alloy characterized in that a porous anodic oxide film is formed on the surface of the aluminum or aluminum alloy and then subjected to secondary electrolysis in an aqueous solution containing a barfluoroalkyl compound. surface treatment method. 2 After forming a porous anodic oxide film on the surface of aluminum or aluminum alloy, this is subjected to secondary electrolysis in an aqueous solution containing a barfluoroalkyl compound, and then,
Heated water at 50°C or higher or 50°C containing the above compound
A method for surface treatment of aluminum or aluminum alloy, characterized by immersing it in the above aqueous solution.