EP0355390A1 - Process for the adsorptive colouring of anodically obtained surfaces - Google Patents

Abstract

The invention relates to a process for the adsorptive colouring of anodically produced surfaces of aluminum and/or aluminum alloys with organic, anionic dyes in aqueous solution. To the dye bath are added water-soluble alkaline earth metal salts in quantities suitable for adjusting the concentration of dissolved sulphate ions in the dye bath to less than 0.1 g/1. In another embodiment, the organic anionic dyes are introduced into the dye bath in the form of their alkaline earth metal salts. The process reduces the sulphate sensitivity of adsorptive colouring with organic anionic dyes.

Description

The invention relates to a process for the adsorptive coloring of anodically produced surfaces of aluminum and / or aluminum alloys with organic, anionic dyes in aqueous solution.

To increase the protection against corrosion, the surface of aluminum and / or aluminum alloys is usually provided with an anodic oxidation with an approximately 20 µm thick porous oxide layer, which can be colored in various ways to achieve decorative effects.

In the generally known methods for coloring surfaces of aluminum and / or aluminum alloys, a distinction is made according to Wernick, Pinner, Zurbrügg, Weiner "Die Surface Treatment of Aluminum", 2nd edition, Leuze-Verlag, Saulgau / Württemberg (1977), pages 296 - 319, 354 - 374, color anodization (integral process), electrolytic and adsorptive coloring.

Adsorptive dyeing processes usually include dyeing techniques in which organic dyes or inorganic pigments penetrate into the pores of the anodically produced oxide layer by single or multiple dipping into aqueous or non-aqueous dyeing solutions, or are formed therein by chemical reaction.

It is known to carry out precipitation reactions within the oxide layer by dipping in FeNH₄ (C₂O₄) ₂ solutions or by alternating dipping in solutions of various other transition metal salts. Such inorganic pigments are very lightfast, but the variety of colors is limited.

With organic adsorptive dyes, on the other hand, colorful and black oxide layers can be easily produced. However, a large number of the known dyes are not sufficiently lightfast, so that they are only suitable for outdoor use to a limited extent.

The previous anodization, i.e. the anodic oxide layer is generally built up according to the so-called GS method. Here, an aluminum workpiece is anodized in a solution containing 150-200 g / l sulfuric acid at a temperature of 18 - 20 ° C and a DC voltage of about 15 to 18 V. The anodizing times are about 3 min / µm layer build-up. Air is usually used during the anodization in an amount of 8 m³ / m²h for circulation and cooling.

The actual coloring is then carried out by immersing the anodized workpiece in an appropriate dye solution at mostly elevated temperatures.

Subsequently, the anodically produced oxide layers are usually compacted in aqueous solution at temperatures in the range from 95 to 100.degree.

The accumulation of sulfate ions in the dyebath is technically unavoidable, since the porous oxide layer in sulfuric acid Electrolyte is generated and sulfate ions get into the dye solution by diffusion during the subsequent coloring. This results in competitive adsorption between sulfate ions and anionic dye molecules when the dye baths are left standing for a longer period of time, which means that the dyeing behavior of the bath is constantly deteriorated.

From Tscheulin: Galvanotechnik, 77 (1987), pp. 3549 - 3553, organic-chemical adsorption dyeing with dyes is known, among other things. Anionic dyes are predominantly used for dyeing. The adsorption of anionic dyes is mainly based on the exchange of the bisulfates of the aluminum oxide surface for dye anions. The author therefore describes that especially acidic dyes, preferably those containing sulfonic acid groups, are suitable for coloring aluminum oxide.

It is described here that, for example, sodium sulfate can remove the dye from undensified layers after dyeing. The reason lies in the fact that part of the adsorbed dye is only bound by ion exchange and can already be partially removed by hot water (bleeding out of the dye). In the presence of free sulfate ions in the subsequent compression process, the above-mentioned competitive adsorption then occurs and the dye is then not adsorbed again. It is therefore proposed to use coloring with dyes which contain phosphate groups, preferably.

The problem of the deterioration of the dye baths was also described in 1977 by Wernick et al., Loc. cit., p. 361 indirectly recognized when it is determined here that no electrolyte in gaps, depressions and the like may remain on the Al workpiece before immersion in the dye bath. A cause or even a solution to the problem is not recognized.

In general, it can be stated that, in order to solve the problem in the prior art, only attempts have been made to modify the dyes themselves, but as a rule these lead to a considerable increase in the cost of the dyeing process.

A similar problem, namely the bleeding of the color during subsequent compression, is also described in Wernick et al., Loc. cit., p. 361. As a measure to prevent the color from bleeding out during subsequent compaction, it is proposed to immerse the already colored workpiece in a 20% barium chloride solution before compaction.

In contrast, the object of the present invention is to provide an improved process for the adsorptive coloring of anodically produced surfaces of aluminum and aluminum alloys with organic anioinic dyes in aqueous solution, it being possible in particular to dispense with an intermediate step between the adsorptive coloring and the compression process .

Another object of the present invention is to extend the service life of the dye baths used for adsorptive dyeing.

It was surprisingly found here that the addition of water-soluble alkaline earth metal salts in an amount which is suitable for binding dissolved sulfate in the dye bath in the form of poorly soluble alkaline earth metal salts is suitable for improving the service life of the dye baths.

It could be shown that the dye baths were largely insensitive to the introduction of sulfate ions from the sulfuric acid anodization with the aid of the process according to the invention.

The above objects are achieved with a process for the adsorptive coloring of anodized surfaces of aluminum and / or aluminum alloys with organic anionic dyes in aqueous solution, characterized in that water-soluble alkaline earth metal salts are added to the dyebath in an amount which is suitable for the concentration dissolved sulfate ions in the dyebath to less than or equal to 0.1 g / l.

Surprisingly, it was found that the alkaline earth metal sulfates formed in the inventive adsorptive coloring do not adversely affect the adsorptive coloring. Even a high concentration of water-soluble alkaline earth metal salt or alkaline earth metal sulfate in the dye bath in no way disturbs the uniformity of the adsorptive dyeing.

With overstoichiometric addition of alkaline earth metal salts, there was also a depot effect, which makes it possible to dispense with the further addition of water-soluble alkaline earth metal salts until the sulfate concentration has reached the critical limit of 0.1 g / l. Accordingly, as long as water-soluble alkaline earth metal ions, in particular barium ions, can be detected qualitatively in the dyebath, it is generally not necessary to add further alkaline earth metal salts. Free alkaline earth metal ions are detected in the dyebath using customary known methods, preferably with precipitation as alkaline earth metal sulfate. In the case of positive detection of free alkaline earth metal ions in the dyebath, the concentration of free sulfate ion is of course also significantly less than 0.1 g / l. The dye bath is usually re-sharpened with water-soluble alkaline earth metal salts when free alkaline earth metal ions can no longer be detected in the dye bath.

The process according to the invention also gains particular importance in continuous spray processes for adsorptive coloring with organic, anionic dyes in aqueous solution, since the dye baths are continuously recycled and new sulfate is always introduced.

A particular embodiment of the invention consists in the use of the alkaline earth metal salts of the organic, anionic dyes. As a rule, the exclusive use of alkaline earth metal salts of the organic, anionic dyes is not sufficient to set the concentration of sulfate ions to less than or equal to 0.1 g / l. In many cases, however, to re-sharpen the dyebaths, it is sufficient to use the barium salts of the dyes directly without the need for further addition of water-soluble alkaline earth metal salts.

According to a preferred embodiment of the present invention, the process is characterized in that mono, bis, polyazo dyes, metal-complex azo dyes, phthalocyanine dyes, quinophthalone dyes, azine dyes, xanthene dyes, nitro, nitroso dyes, di- as organic anionic dyes and / or their alkaline earth metal salts. , Triphenylmethane dyes, indigoid dyes, methine dyes, anthraquinone dyes or mixtures thereof.

All of the above-mentioned dyes are inherently more or less sensitive to sulfate in the adsorptive coloring of anodically produced surfaces of aluminum and / or aluminum alloys, which results from the sulfate ions introduced from the previous step of building up the anodic oxide layer of the surface. With the help of the present invention it is possible to compete improve sorption between the dye molecule and sulfate ion in the direction of the dye molecule.

In particular, xanthene dyes show a strong sensitivity to the presence of sulfate ions in the dyebath.

In the course of the investigations of the present invention it was found that the limit values for the sulfate sensitivity in the dyes are of the order of 0.1 g / l. According to the invention, this means that at concentrations of more than 0.1 g / l there is insufficient coloring of the anodically produced surface for industrial use. It is believed that this sulfate sensitivity has hitherto hindered the widespread use of adsorptive staining with xanthene dyes.

Accordingly, a further embodiment of the present invention is that xanthene dyes are selected from fluorescein, eosin, 2,7-dichlorofluorescein, eosin scarlet, 4,5,6,7-tetrachlorofluorescein, cyanosine, calcein, 4-aminofluorescein, 4,5-diiodofluorescein , 4,5-dibromofluorescein, 5-aminofluorescein, methyleosin and / or erythrosin or their alkaline earth metal salts.

• a) Gute Aufnahme des Farbstoffes in die Oberfläche des Aluminiums
• b) hohes Färbevermögen für anodisch erzeugtes Aluminium,
• c) hohe Eindringtiefe in die Poren der Oxidischicht und
• d) gute Lichtbeständigkeit gegenüber ultravioletter Strahlung.

In order for a dye to be suitable as a dye for coloring aluminum oxide layers, it must meet the following criteria:

• a) Good absorption of the dye in the surface of the aluminum
• b) high coloring capacity for anodically produced aluminum,
• c) high depth of penetration into the pores of the oxide layer and
• d) good light resistance to ultraviolet radiation.

Although in principle all alkaline earth metal salts of the above-mentioned dyes can be used, it is usually necessary to use additional alkaline earth metal salts which have a particularly low solubility product in the formation of alkaline earth metal sulfates. In principle, however, the process for adsorptive dyeing is characterized in that water-soluble calcium, strontium and / or barium salts are added to the dye bath or the dyes in the form of their calcium, strontium and / or barium salts together with other water-soluble alkaline earth metal salts starts. The use of the corresponding calcium salts is less preferred if the dyes to be used have been found to be extremely sensitive to sulfate. The use of water-soluble barium salts is particularly preferred due to the solubility product of barium sulfate.

Accordingly, a further embodiment of the present invention is characterized in that calcium salts are added to the dyebath. These are used in particular for less sulfate-sensitive dyes.

Due to the extremely low solubility product of barium sulfate compared to strontium sulfate and calcium sulfate, the amount of barium salts to be used can be set extremely low if necessary. However, the minimum amount should be set so that the concentration of free sulfate ions in the dyebath is less than 0.1 g / l.

The upper limit of the alkaline earth metal salts to be used is practically determined by the solubility of these salts in the dyebath. For the purposes of the present invention, it is less preferred that the alkaline earth metal salts in concentrations are used in which the alkaline earth metal salts do not dissolve. Rather, it is entirely possible within the scope of the present invention to blend the alkaline earth metal salts of the organic, anionic dyes with the corresponding organic anion dyes themselves in such a way that the object according to the invention is achieved. This succeeds in particular when the content of alkaline earth metal salt of the dye in the mixture of alkaline earth metal salt of the organic anionic dye and the free organic anionic dye is sufficient to bind dissolved sulfate in the dye bath quantitatively in the form of poorly soluble alkaline earth metal sulfates.

A depot effect is achieved by an excess of free alkaline earth metal ions in the dyebath. Larger amounts of free alkaline earth metal ions do not interfere with the dyeing process any more than the failed alkaline earth metal sulfates.

Practically all water-soluble alkaline earth metal salts can be used as the alkaline earth metal salts to be added. The corresponding alkaline earth metal halides, nitrates, nitrites and / or acetates can be used here, inter alia, for the purposes of the present invention. However, the alkaline earth metal nitrates and / or acetates are preferably used.

In a preferred embodiment of the present invention, the organic anionic dye and / or their alkaline earth metal salts are used in an amount of 0.05 to 20 g / l in the dyebath.

A preferred embodiment of the present invention consists in that the organic anionic dyes and / or their alkaline earth metal salts in an amount of 0.5 to 5 g / l. In principle, the pH of the adsorptive coloring is not critical. However, in order to keep the dyes in solution as salts, it is preferred according to a preferred embodiment of the present invention to adjust the pH in the range from 1 to 8. In a preferred embodiment of the present invention, a pH in the range from 3 to 8 is set. In a preferred embodiment, the temperature during the coloring in the range from room temperature to the boiling point, preferably in the range from 40 to 70 ° C.

After the adsorptive coloring has taken place, the oxide layers are subjected to generally known compression processes. During this compression, anhydrous Al₂O₃ turns into hydrate, which takes up a larger volume and thereby closes the pores. The subsequent compression essentially prevents leaching out of the paint, at the same time improves the light fastness and also generally increases the corrosion resistance of the layer.

Accordingly, a preferred embodiment of the present invention consists in compacting the colored surfaces of aluminum and / or aluminum alloys.

A combination of electrolytic and adsorptive dyeing is also included in the scope of the present invention. Here, the oxide layer is usually first electrolytically pre-colored in a light to dark bronze tone and then directly over-colored with the organic, anionic dyes and / or their alkaline earth metal salts in a second bath. Two different, coloring, real substances - deposited metal and dye molecule lie on top of each other in the layer and do not interfere with each other. The layers are as hard as in the case of electrolytic coloring.

The dyeings are carried out by methods known per se, for example by dipping or spraying.

Examples

In the following examples, the name of the aluminum alloy is given in accordance with DIN 3315, material no. 3; AlMg 1 was used.

The sheets are degreased in an aqueous solution consisting of 5% P₃-Almeco ^R 18 (alkaline cleaner containing borates, carbonates, phosphates and nonionic surfactants) at a temperature of 70 ° C. It was then pickled in a long-term pickle using 112 g / l of dissolved aluminum and 80 g / l of NaOH using P₃-Almeco ^R 46 (pickling agent containing alkali, alcohols and salts of inorganic acids). P₃-Almeco ^R 46 was dosed in a ratio of 1: 6 to NaOH. At 65 ° C was about 15 min. stained.

Subsequently, using an aqueous solution containing 5% P₃-Almeco ^R 90 (paper remover containing salts of inorganic acids and inorganic acids) at room temperature in the course of 3 min. pickled.

After each process step, the sheets were rinsed thoroughly with deionized water.

The subsequent anodization was carried out after the direct current sulfuric acid process;

Bath composition: 200 g / l sulfuric acid, 10 g / l aluminum; Air injection 8 m³ / m²h; Temperature: 20 ° C DC voltage: 15 V. The anodizing time was about 3 min per µm layer build-up; i.e. the total anodizing times for the oxide layers of approximately 20 μm given in the examples below were approximately 45 to 70 minutes.

The sheets were then colored as described in the examples below.

After thorough rinsing again with deionized water, the colored surfaces were compacted in a water bath at temperatures of about 96 to 98 ° C.

example 1

Using a dyebath containing 0.5 g / l fluorescein sodium and 6.13 g / l barium acetate, a yellow-gold coloration of an anodized was obtained at a pH of 7.5 over a period of 15 minutes at a temperature of 60 ° C Made of aluminum sheet.

Comparative Example 1a:

Using a dyebath containing 0.5 g / l of fluorescein sodium, a yellow-gold coloration of an anodized aluminum sheet was produced at a pH of 7.5 over a period of 15 minutes at a temperature of 60 ° C.

Comparative Example 1b:

Using a dyebath containing 0.5 g / l fluorescein sodium and 0.1 g / l ammonium sulfate was at a pH of 7.4 over 15 minutes at a temperature from 60 ° C produced a yellow-gold coloration of an anodized aluminum sheet.

Comparative Example 1c

Using a dyebath containing 0.5 g / l of fluorescein sodium and 0.5 g / l of ammonium sulfate, a pale yellow-gold coloration of an anodized solution was obtained at a pH of 7.4 over a period of 15 minutes at a temperature of 60 ° C. Made of aluminum sheet.

The comparison of Example 1 with Comparative Examples 1a, 1b and 1c shows the influence of the sulfate sensitivity when using fluorescein sodium. In the order of magnitude of 0.1 g / l sulfate ions, no disturbing influence is noticeable. In addition, however, a significantly lighter color is obtained.

Example 2:

Using a dyebath containing 2.0 g / l yellowish eosin and 6.13 g / l barium acetate at pH 5.4 over a period of 15 min. At a temperature of 60 ° C a red coloring of an anodized aluminum sheet is produced.

Comparative Example 2a:

Using a dyebath containing 2 g / l of eosin yellowish, a red coloration of an anodized aluminum sheet was produced at pH 5.5 over a period of 15 minutes at a temperature of 60 ° C.

Comparative Example 2b:

Using a dyebath containing 2.0 g / l yellowish eosin and 0.1 g / l ammonium sulfate, the pH was adjusted to 5.5 over a period of 15 min. produced a red coloration of an anodized aluminum sheet at a temperature of 60 ° C.

Comparative Example 2c:

Using a dyebath containing 2 g / l of eosin yellowish and 0.5 g / l of ammonium sulfate was at a pH of 5.5 in the course of 15 min. A light red-pink coloration of an anodized aluminum sheet is produced at a temperature of 60 ° C.

The comparison of Example 2 with Comparative Examples 2a, 2b and 2c confirms the sulfate sensitivity when stained with eosin yellowish; a concentration of less than 0.1 g / l is regarded as the limit for the maximum amount of sulfate ions in the dyebath. It was also proven that barium ions do not negatively influence the color.

Example 3:

Using a dyebath containing 1.0 g / l of 2,7-dichlorofluorescein and 6.27 g / l of barium nitrate, a copper was removed at a pH of 5.6 over a period of 15 minutes at a temperature of 60 ° C. colored coloring of an anodized aluminum sheet.

Comparative Example 3a:

Using a dyebath containing 1.0 g / l of 2,7-dichlorofluorescein, a copper-colored staining of an anodized aluminum sheet was produced at a pH of 5.7 over a period of 15 min at a temperature of 60 ° C.

Comparative Example 3b:

Using a dyebath containing 1.0 g / l of 2,7-dichlorofluorocecein and 0.1 g / l of ammonium sulfate, the pH was adjusted to 5.6 over a period of 15 min. a copper-colored coloring of an anodized aluminum sheet was produced at a temperature of 60 ° C.

Comparative Example 3c:

Using a dyebath containing 1.0 g / l of 2,7-dichlorofluorescein and 0.5 g / l of ammonium sulfate at a pH of 5.7 over a period of 15 minutes at a temperature of 60 ° C., a pale copper-colored color was obtained of an anodized aluminum sheet.

The comparison of Example 3 with Comparative Examples 3a, 3b and 3c gives a limit value for the maximum sulfate ion concentration of less than 0.1 g / l of sulfate ions. Here, too, it can be seen that barium salts do not negatively influence the color.

Example 4:

Using a dyebath containing 0.5 g / l fluorescein sodium and 79.9 g / l barium acetate was used in a pH of 7.2 over a period of 15 minutes at a temperature of 60 ° C. produced a yellow-gold coloration of an anodized aluminum sheet.

Example 4a

Using a dyebath containing: 0.5 g / l fluorescein sodium, 27.7 g / l ammonium sulfate and 79.9 g / l barium acetate was at a pH of 7.2 over a period of 15 minutes at one temperature from 60 ° C produced a yellow-gold coloration of an anodized aluminum sheet. This corresponded to the coloring according to Example 4.

Example 4b

Using a dyebath containing: 0.5 g / l fluorescein sodium, 41.3 g / l ammonium sulfate and 79.9 g / l barium acetate at a pH of 7.2 over 15 minutes at a temperature of 60 ° C produced a yellow-gold coloration of an anodized aluminum sheet. The coloration corresponded to that of Example 4.

Comparative Example 4:

Using a dyebath containing 0.5 g / l fluorescein sodium and 0.7 g / l ammonium sulfate, the anodized aluminum sheet was not colored at a pH of 7.2 over a period of 15 minutes at a temperature of 60 ° C. .

Examples 4, 4a and 4b as well as comparative example 4 show in particular the depot effect of a large alkaline earth metal ion concentration. It can also be seen that a Large amounts of free alkaline earth metal ions or alkaline earth metal salt deposits in the dyebath have no disruptive influence.

Example 5:

Using a dyebath containing 5.0 g / l Sanodalrot ^R B 3LW (heavy metal complex azo dye) and 19.4 g / l barium acetate, the pH was 5.7 over a period of 15 minutes at a temperature of 60 ° C made a red coloration of an anodized aluminum sheet.

Example 5a

A red coloration of an anodized aluminum sheet was produced using the dyebath according to Example 5 with the further use of 5.0 g / l ammonium sulfate under the above-mentioned conditions.

Example 5b

Using a dyebath according to Example 5a, further using 5 g / l ammonium sulfate, a red coloring of an anodized aluminum sheet was produced under the above-mentioned conditions.

Example 5 c (comparative example):

Using a dyebath according to Example 5 without barium acetate, further using 10 g / l ammonium sulfate, a light pink coloration of an anodized aluminum sheet was produced under the above-mentioned conditions. Almost no color buildup could be observed.

Example 5d:

Using a dyebath according to Example 5c, a further red coloration of an anodized aluminum sheet was produced using 19.4 g / l barium acetate under the above-mentioned conditions.

Comparative Example 5:

Using a dyebath containing 5 g / l Sanodal red ^R B 3LW, a red coloration of an anodized aluminum sheet was produced at a pH value of 5.7 over a period of 15 minutes at a temperature of 60 ° C.

Examples and comparative examples 5 show in an impressive manner the dependence of the quality of the color coating on the sulfate ion concentration. While in Example 5c the sulfate ion concentration is sufficient to influence the competitive adsorption of sulfate ions and dye molecule accordingly, an excellent color can be observed again by adding alkaline earth metal salt as in Example 5d.

Example 6:

Using a dyebath containing 5 g / l sanodal blue G ^R (anthraquinone dye, not metallized), 12.1 g / l barium nitrate and 6.1 g / l (NH) ₂SO₄ was at a pH of 5.5 in the course a blue color of an anodized aluminum sheet was produced for 15 minutes at a temperature of 60 ° C.

Comparative Example 6:

Using a dyebath containing 5 g / l of Sanodal Blue ^R , a blue color was produced at a pH of 5.5 over a period of 15 minutes at a temperature of 60 ° C.

Claims (17)

1. A process for the adsorptive coloring of anodically produced surfaces of aluminum and / or aluminum alloys with organic, anionic dyes in aqueous solution, characterized in that water-soluble alkaline earth metal salts are added to the dyebath in an amount which is suitable for the concentration of dissolved sulfate ions in the Set the dye bath to less than or equal to 0.1 g / l. 2. The method according to claim 1, characterized in that water-soluble alkaline earth metal salts are added to the dyebath in an amount which is suitable for subsequently detecting dissolved alkaline earth metal ion in the dyebath. 3. The method according to claim 1 or 2, characterized in that water-soluble alkaline earth metal salts of organic, anionic dyes are used in the dyebath. 4. Process according to Claims 1 to 3, characterized in that mono, bis, polyazo dyes, metal-complex azo dyes, phthalocyanine dyes, quinophthalene dyes, azine dyes, xanthene dyes, nitro, nitroso dyes, di-, as organic anionic dyes and / or their alkaline earth metal salts Triphenylmethane dyes, indigoid dyes, methine dyes, anthraquinone dyes or mixtures thereof. 5. The method according to claim 4, characterized in that xanthene dyes are selected from the group consisting of fluorescein, fluorescein sodium, eosin yellowish, 2,7-dichlorofluorescein, eosin scarlet, 4,5,6,7-tetrachlorofluor escein, cyanosine, calcein, 4-aminofluorescein, 4,5-diiodofluorescein, 4,5-dibromofluorescein, 5-aminofluorescein, methyleosin and erythrosine. 6. Process according to claims 1 to 5, characterized in that water-soluble calcium, strontium and / or barium salts are added to the dyebath and / or the dyes are used in the form of their calcium, strontium and / or barium salts. 7. The method according to claim 4, characterized in that water-soluble barium salts are added to the dyebath. 8. Process according to claims 1 to 7, characterized in that the fluorides, chlorides, bromides, iodides, nitrites and in particular the nitrates and / or acetates are used as water-soluble alkaline earth metal salts. 9. Process according to claims 1 to 8, characterized in that the dyes and / or their alkaline earth metal salts are used in an amount of 0.05 to 20 g / l. 10. The method according to claims 1 to 8, characterized in that one uses the dyes and / or their alkaline earth metal salts in an amount of 0.5 to 5 g / l. 11. The method according to claims 1 to 10, characterized in that adjusting the pH of the dyebath in the range of 1 to 8. 12. The method according to claims 1 to 10, characterized in that adjusting the pH of the dyebath in the range of 3 to 8. 13. The method according to claims 1 to 12, characterized in that the temperature of the dyebath is set in the range from room temperature to the boiling temperature. 14. The method according to claims 1 to 12, characterized in that the temperature of the dyebath is set in the range from 40 to 70 ° C. 15. The method according to claims 1 to 14, characterized in that the surfaces are colored by dipping and / or spraying. 16. The method according to claims 1 to l5, characterized in that after dyeing by electrolytic dyeing by an adsorptive dyeing with organic anionic dyes. 17. The method according to claims 1 to 16, characterized in that one compresses the colored surface of aluminum and / or aluminum alloys.