JPS605896A - Treatment of aluminum and its alloy as substrate - Google Patents

Abstract

PURPOSE:To improve the adhesion of Al or an Al alloy to a paint film by making the surface of the metal satin by a mechanical means and by carrying out electrolysis in an electrolytic soln. prepd. by adding an oxygen compound to a sodium chloride soln. CONSTITUTION:The surface of Al or an Al alloy is made satin by mechanical means such as sand blasting, shot blasting or wire scratching. Since the resulting satin surface has unsatisfactory adhesion to a paint film electrolysis is carried out in an electrolytic soln. prepd. by adding a small amount of an oxygen compound such as phosphoric acid, sulfuric acid or oxalic acid to a sodium chloride soln. By the electrolysis the satin surface is made finer to improve the anchoring effect and the adhesion to a paint film or a sheet. The surface after coating is also improved.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention provides a method for treating aluminum and its alloys,
More specifically, the present invention relates to a surface treatment method that is used as a preliminary treatment when applying paint or pasting a sheet to the surface of aluminum and its alloys.

Generally, when applying paint or pasting a sheet to the surface of aluminum and its alloys (hereinafter simply referred to as aluminum), an aluminum base is used to increase the adhesion strength of the paint film and the sheet to the aluminum. As a treatment, a matte surface is formed on the aluminum surface by mechanical treatment means such as sandblasting or chemical treatment means using an acid or alkaline solution, and the paint is applied and a sheet is pasted on this matte surface. It has been known.

The pear-shaped surface formed on the surface of the leek was rough and had a poor anchoring effect, and the adhesion strength of the coating film and sheet to aluminum was weak.

In addition, when using the above-mentioned chemical treatment means, in order to remove the base treatment solution (acid or alkaline solution), aluminum, and reaction products, a body that has been repeatedly washed with an acid solution such as nitric acid and water, or a body that has been repeatedly washed with an acid solution such as nitric acid, or with sodium carbonate or The surface treatment process is completed by neutralizing the surface using caustic soda or the like and then drying it, but with such chemical treatment methods,
It requires many steps, which increases the processing time and product cost, or it requires a large number of processing tanks.
This has the disadvantage that the entire device becomes large.

Therefore, as a conventional surface treatment method for aluminum, for example, in Japanese Patent Publication No. 48-169.70, a surface treatment method is proposed in which an electrolytic layer is prepared using chloride, bromide, or iodide, and aluminum is anodized in the electrolytic bath. However, it has been found that such a treatment method causes the following problems when surface treatment of aluminum is performed on a factory scale.

That is, when performing surface treatment on a large amount of aluminum, usually two aluminum workpieces are placed in one jig, the treated side facing outward, each workpiece [IXl] supported with a predetermined gap, and rhl Wl': Each workpiece is anodized by applying electricity to each workpiece through a jig. At this time, a brown dot is placed near the jig on the opposite surface of each workpiece. In some cases, the areas where the skin appeared, also turned white and became moldy.

Particularly when manufacturing containers such as Teflon pots, one side of the aluminum is subjected to surface treatment.
The surface is shaped like Dν, the pear surface is repainted with Teflon, and the aluminum is coated with Dy so that this Teflon coated surface becomes the inner surface.
However, at the time of molding, the dots and dots are exposed on the surface opposite to the painted surface, that is, on the outer surface of the container, which lowers the product price. was there.

The dots and warblers can be eliminated by applying separate cloth M, but when doing so, the number of steps increases and the cost increases. It is desirable to prevent housing as much as possible.

Recently, a sheet has been pasted on the surface of aluminum,
Although aluminum processing technology is widely used in which the aluminum to which the above-mentioned sheet is attached is press-formed into products after C4 pre-coating, the technique disclosed in the above-mentioned publication does not contain fluorocarbon on the aluminum surface. This is a surface treatment method developed for applying resin, and since the treatment using this surface treatment method (ti) i-, only a grainy surface and a fine matte surface were formed, the sheet was pasted on the treated surface. The present invention was made in view of the above-mentioned problems, and its purpose is to eliminate the problems caused by the occurrence of dots and insects. The object of the present invention is to provide a method for surface treatment of aluminum which is of good quality and can significantly increase the density and strength of coating films and sheets.

However, Kinoe Qlj applied a satin finish to the aluminum surface by mechanical means! After this aluminum is electrolytically treated in an electrolytic bath containing a sodium chloride solution as a main component and oxygen compounds such as phosphoric acid and sulfuric acid added thereto.

As the mechanical means for applying the matte finishing, Zan 7... Trust, short blast, hairline and scar A means such as a clutch wire is adopted.

In addition to the above-mentioned phosphoric acid and sulfuric acid, oxalic acid or sodium bisulfate can be used as additives to be added to the sodium chloride solution when manufacturing W1j of the above-mentioned electric M5&. Prepare Denwaku by adding it to a sodium chloride solution.

The bath composition of this electrolytic bath was sodium chloride 0.5-1Q;
3wt%, phosphoric acid 0.1-2 [1wt%, sulfuric acid 0.05
~20Wt%, oxalic acid 0.2~3.0VOIK N
It is desirable that the sodium sulfate content be 0.01 to 2-OV=t%.

In this way, a rough satin surface is formed on the aluminum surface by mechanical means, and then electrolytically treated using an electrolytic bath. By forming a cyan anchor effect on each of these matte surfaces, it strengthens the adhesion of the coating film and sheet, and moreover, it has been possible to obtain a base treated surface with an excellent appearance without causing spots or moldiness on the aluminum surface. It was.

In particular, as a result of applying clear paints made of epoxy nylon, acrylic, and urethane resin B°1'' to the treated aluminum surface, all paints adhered firmly to the treated surface and the finished appearance was good. Met.

In addition, a Teflon film made of fluorinated ethylene (manufactured by Asahi Glass Co., Ltd.) is laminated (heat treated at 280 to 350°C) on the aluminum-treated surface to provide a temperature of +250 to 600°C.
As a result of firing the aluminum for 5 to 15 minutes at ℃ and drawing it with a press, the surface area of the film was 1.9 to 1.
It was confirmed that even when the film was increased by 20 times, the film did not peel off from the aluminum and could be sufficiently used for deep drawing.

The aluminum is degreased with caustic soda or the like after the formation of a satin finish by mechanical means and before electrolytic treatment.In order to prevent natural oxidation accompanying the formation of a matte finish, the aluminum is degreased immediately. need to be electrolytically treated.

When the aluminum is electrolytically treated, direct current or alternating current is used as the power source, and the current density is 1. D～"'d
i' Voltage 5.0-20. OV, time 5.0-10
．． It will be done in 0 minutes.

Furthermore, at the start of the electrolytic treatment, the aluminum is immersed in the electrolytic bath for 60 seconds or more without energizing the aluminum.
Najimi treatment is carried out for one minute, and by doing so, the finished appearance of the aluminum surface can be improved.

Also, during the electrolytic treatment, a settling tank is provided in addition to the treatment tank,
It is preferable to carry out the electrolytic treatment while circulating the electrolytic bath between each of these columns, so that the reaction products generated in the treatment tank are precipitated and removed in a settling tank. In this case, the electrolytic bath in the treatment tank is It can be kept fresh and can be used for good electrolytic treatment of aluminum, making it a non-polluting treatment.

Furthermore, after the electrolytic treatment, the aluminum is pickled with nitric acid or the like and washed with water, so that the color adhering to the aluminum treated surface is removed and the beautiful texture of the aluminum is exposed on the entire surface. .

Note that the present invention can also be applied to aluminum and aluminum alloys.

Next, the present invention will be explained by giving specific examples.

Example 1 (1) Sample: A 99.8% aluminum plate was used.

(2) Mechanical satin finishing: using a sandblasting machine, grinding particle size 100 mesh, air pressure 4.0'fi,
I was gone in 20 seconds.

(3) Degreasing treatment: Using 5φ caustic soda, it was heated at 65°C.
The sample was heated to 2 minutes and immersed for 2 minutes, and then washed with water.

(4) Setting: Two aluminum plates treated in (2) and (3) above were used, and each plate was placed back to back and supported on a jig.

(5) TW f! l/r processing: 3. Qwt% sodium chloride solution, phosphoric acid Q, 2wt%, sulfuric acid Q, 1
An electrolytic bath was prepared by adding 5 vol.

The aluminum plate set in (4) above was electrolessly immersed in this electrolytic bath for 30 seconds to perform a pear treatment.

After that, the aluminum plate was connected to the DC 8. Ovs,'
Anodized at ttL flow-tightness [20/-1 hour 7 minutes.

(6) Post-treatment: The aluminum plate was removed from the jig, immersed in 10% nitric acid for 15 minutes, and then washed with water using a shower. Furthermore, after this, it was immersed in a 5-chloride wet solution of caustic soda for 30 seconds to neutralize it, washed with water in a shower for 30 seconds, and dried with hot air.

(7) Results: On the treated surface of the aluminum plate treated as above, (a) Spray paint with epoxy paint and
I baked it separately.

(b) A 50 μm Teflon film (manufactured by Asahi Glass Co., Ltd.) was laminated at a temperature of 660°C and baked at 280°C.

Both of the above (a)←) had excellent mechanical strength against the aluminum plate, and there were no dots or worms on the surface of the aluminum plate, and the finished appearance was good.

Example 2 The above (1) (21 (31 (4)) was carried out under the same conditions as in Example 1.

(5) Electrolytic treatment: 1. Qwt J sodium chloride solution, Su7 f,', Q Q8wtt4 and oxalic acid 0
．． vol% and weight'5) IC acid soda 0.02Wt
% was added to prepare electrolytic baths of V and V.

The aluminum plate was electrolessly immersed in this ilE j17 bath for 60 seconds to perform a dipping treatment.

After this, aluminum & DC 10. OV, current density i
25/d, 7 minutes, and 8 minutes of anode oxidation treatment.

(6) Post-treatment: This was carried out in the same manner as in Example 1 above.

(7) Conclusion! f-: Same as Example 1, (A) (
(b) Trial ■ was conducted.

Both (a) and (b) above had excellent dense layer strength against the aluminum plate, had no dots or worms on the surface of the aluminum plate, and had a good finished appearance.

patent applicant To, 4-

Claims (3)

[Claims] (1) After applying a matte finish to the surface of aluminum and its alloys by mechanical or manual means, the aluminum and its alloys are processed using a computer-based method consisting of a sodium chloride bath solution as a main component and an oxygen compound added thereto. , 'jti, surface treatment method for aluminum and its alloys, characterized by subjecting it to a solution treatment. (2) Surface treatment of aluminum and alloys thereof according to claim (1), characterized in that the satin finish treatment is performed by a thorough treatment method such as sandblasting, hairline treatment, or scratch wire treatment. Law. (3) 'rjtjl'+'bath 1τ The aluminum and its alloy according to claim (1), characterized in that the oxygen compounds added are phosphoric acid, sulfuric acid, oxalic acid, and sodium bisulfate. Surface treatment method.