DE3311882A1 - MATERIAL PIECE OF ALUMINUM, PREFERABLY ALUMINUM SHIELD AND METHOD FOR PRODUCING THE SAME - Google Patents

Description

The invention relates to a piece of material made of aluminum, preferably an aluminum sign with a light anodized surface, on the dark contrasting one Characters, patterns or images are formed. The invention also relates to a method of manufacture such objects, the characters, patterns or images generated by means of high-energy laser beams will.

The application of patterns or labeling of signs can be used particularly economically can be carried out by appropriately controllable laser beam writers. Such laser beam writers are known and not the subject of the invention. With an appropriately controlled, high-energy laser beam the material to be inscribed is partially melted and / or evaporated, so that the so The treated surface usually contrasts with its surroundings. Steel plates that are at show tempering colors with this method, for example, without major exposure to heat Effort to be labeled. The process can also be used on dark-colored anodized aluminum surfaces insert. The dyes stored in the anodized layer are evaporated by the laser energy and the result is an aluminum-colored, light font, pattern or image that contrasts with the surroundings.

The known method fails, however, when labeling frequently used natural colors, i. E.

metallic anodized aluminum surfaces. The aluminum-colored one The trace of the laser beam hardly stands out from its surroundings. The invention is therefore the object based on a process to create a colored, in particular black writing can be generated by means of laser beams.

According to the invention, this object is achieved by the method steps specified in the characterizing part of claim 9 solved.

Fundamental to understanding the invention is the so-called "anodizing process", i.e. a process In the case of anodic treatment in an aqueous electrolyte on aluminum a firmly adhering oxide coating is produced. The anodizing process is known and for example in the manual of electroplating, Volume 3, Karl Hauser Verlag, Munich, 1969, pages 1-80 described in detail.

The anodic oxidation leads to the formation of so-called micropores on the surface, which have a high adsorptive power for inorganic and organic substances, for example Own dyes. Because of these properties, the anodized aluminum can be made of almost any material Grant shade. In the case of light anodized aluminum, no dyes are stored in the micropores ; the post-treatment, called compression, closes the micropores and takes place simple boiling (swelling) in water. During this redensification, the is formed on the outside Anodized layer and a thin layer of Al oxide hydroxide in the pores. Since this layering with a When the increase in volume is going on, the pores close completely. It is also known to improve Sealing effects the surfaces with hot metal salt solutions, for example chromate, acetate or Treat silicate solutions. In this case, however, the concentration is at most about 20g / l. One Labeling such aluminum surfaces with a laser beam does not lead to any result because the color effects are too low.

According to the invention, substances that are initially colorless are now stored in the micropores before compression

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or absorb only a little in the visible range of the spectrum. The structure of these substances is, however, at Exposure to a high-energy laser beam changed and discolored, so that the discoloration opposite the metallic environment not acted upon by the laser beam emerges in a contrasting manner. The discoloration can take place through various mechanisms; a cleavage of chemical bonds is possible, for example an oxidation, a re-coordination or a polymerization. It is crucial in the present context only that the high-energy laser beam transforms the connections in such a way that they create a dark, take on a contrasting shade.

In a further advantageous embodiment of the invention substances are stored in the pores of the anodized layer, which depends on the irradiated laser power produce different colors by first, including the anodized layer form a colored compound and with higher laser power by additional cleavage of chemical bonds and / or renewed re-coordination to form a differently colored, preferably black, compound.

The advantages of the invention consist in the fact that it is now also possible to use light anodized aluminum surfaces to produce dark contrasting lettering using laser beams. The possibility of being dependent Writing in two colors from the energy of the laser beam is considered particularly beneficial.

The invention is described in more detail below with the aid of a few examples.

Example 1: Generation of the discoloration by polymerization.

The anodized, but still undeserved aluminum surface

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with an anodized layer of about 20μ is ^{exposed to an aqueous glucose solution at about 70 0} C for 10 to 15 minutes. The concentration of the solution is between 500 and 1000 g of glucose monohydrate per liter of water. The glucose hydrate is stored in the pores of the anodized layer. The anodized layer is then compacted in a boiling, equally strong aqueous glucose solution for approx. 1 hour. This prevents the glucose from escaping from the pores.

If laser beams act on a layer treated in this way, the glucose candles and yellows are formed to brown shades. When the laser power is high, the chemical bonds are broken and it is created black carbon.

Example 2: Generation of different colors by umkoordination including the anodized layer.

The anodized object is at elevated temperature (7 0 ⁰ C) a strong aqueous cobalt salt solution, preferably cobalt acetate (Co (CH ₃ -CoO) ₂ ). The concentration is about 250 g / l and the duration of the treatment should be between 10 and 15 minutes. The surface treated in this way is then compacted in an equally strong, boiling aqueous solution.

If a surface treated in this way is exposed to laser beams, cobalt oxide is formed, which immediately _{crystallizes with the aluminum oxide of the anodized layer to form a blue double oxide (Al 2} CoO ₄ ). The color is known as what is known as "Thenard Blue".

At high laser power, this double oxide breaks down and only the black cobalt oxide is produced.

Example 3: Incorporation of elements that influence the compression process in the form of ions.

For example, chromium compounds can be used together with lead compounds to produce a red discoloration Form the yellow-red lead chromate (PbCrO.). However, since both chromium ions and lead ions interfere with the compression process, the two elements must be insoluble in water Compounds are embedded in the micropores. This is best done by precipitating insoluble ones Compounds, preferably the carbonates. To do this, the anodized object is placed under the Rinse several times alternately in the aqueous salt solutions, for example nitrate solutions and one dipped in aqueous sodium carbonate solution.

The anodized layer can then be compacted in boiling water. The concentration of the chromium compounds and lead compounds in the form of soluble nitrates is between 250 and 500 g / l.

Example 4: Formation of different colors through progressive deterioration of chemical bonds.

In hot water it turns into ammonium vanadate (NH.VO ^) dissolved with a little ammonia. The anodized object is immersed in the resulting solution to make ammonium monovanadate to be stored in the pores of the anodized layer. The concentration is about 100 g / l.

The anodized layer is then compacted in a boiling solution of the same strength. If laser beams act on the surface treated in this way, the red vanadium oxide (V ₉ Oj-) forms first or, with higher laser power, the bluish oxide (VO ₉ ).

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Example 5: Formation of dark writing by oxides.

The anodized article becomes an aqueous nickel salt solution, preferably nitrate, at an elevated temperature or acetate and then compressed in a boiling solution of the same strength.

Laser beams produce black discolorations through the formation of nickel oxide (Ni ₃ O ₃ ).

If the nickel compounds are replaced by the analogous manganese compounds, the inherent color of the surface is particularly low. The black discoloration caused by laser beams is caused by manganese dioxide (MnO ₂ ).

Claims (19)

KMK) IiKU \ ΚΚΙ!> Αΐ \ ΠΠ "- \ ||; -; <Γ \: · | Ι: | 1! ^. Π::.: IMiATWW Mll'K K 2ΰ 21G / 7we Carl Baasel Lasertechnik KG Sandstrasse 21
8000 Munich 2 Piece of material made of aluminum, preferably aluminum shield and "method for producing the same. Claims ■ fly piece of material made of aluminum, preferably aluminum shield with a light anodized surface on which darkly contrasting characters, patterns or images are formed are, characterized in that the anodized layer contains substances that are acted upon by a laser beam of high energy density, possibly reacting with the anodized layer have changed and are colored in a contrasting color to the surroundings. 10 2. Piece of material according to claim 1, characterized in that the substance is glucose hydrate. 3. Piece of material according to claim 1, characterized in that the substance is a cobalt salt, is preferably cobalt acetate. 4. Piece of material according to claim 3, characterized in that the anodized layer additionally nor zinc compounds, preferably an acetate or nitrate. 5. Piece of material according to claim 1, characterized in that the substances are a mixture are made of lead carbonate and chromium carbonate. 6. Piece of material according to claim 1, characterized in that g e - indicates that the substance is ammonium vanadate is. 7. Piece of material according to claim 1, characterized in that the substance is a nickel compound, preferably a nitrate or acetate. 8. Piece of material made of aluminum, preferably an aluminum plate with a light anodized surface the dark contrasting characters, patterns or images are formed, characterized in that, that the characters, patterns or images by areas darkly discolored in relation to their surroundings in the form of Thenard blue (Al-CoO.) formed in the oxide layer are present. 9. Process for applying characters, patterns or images to a lightly anodized aluminum surface by applying a correspondingly controlled laser beam of high energy density to the surface, characterized in that the aluminum surface is first anodically oxidized and that substances are then stored in the micropores of the fresh, non-compacted surface, which are able, under the influence of the laser beam energy, to change their composition through chemical cleavage Bonds and / or by re-coordination and / or polymerization, optionally including the Oxide layer to change and discolor, the aluminum surface with one of these substances or their starting components are wetted in a solution containing a high concentration at elevated temperature or is immersed in this, that the micropores are then sealed by boiling in, preferably the same solution takes place and that finally the metallic-looking surface with the laser beam is applied, whereby the characters, patterns or images by discoloration of the stored substances stand out in contrast. 10. The method according to claim 9, characterized in that by controlling the energy of the Laser beam, the stored substances react differently and differently depending on the energy intensity Form discoloration. 11. Method according to claim 10, characterized in that g e k e η nz E i c h η e t that the freshly anodized aluminum surface of an aqueous cobalt salt solution, preferably exposed to a cobalt acetate solution. 12. The method according to claim 11, characterized in that that the solution also contains zinc ions in the form of dissolved acetates or nitrates. 13. The method according to claim 10, characterized in that that the freshly anodized aluminum surface is an aqueous solution of ammonium vanadate (NH.VO-.) And ammonia. 14. The method according to claim 10, characterized in that that the freshly anodized aluminum Surface is exposed to an aqueous glucose solution. 15. The method according to claim 10, characterized in that g e k e η η, that the freshly anodized aluminum surface of an aqueous nickel salt solution, preferably exposed to a nickel nitrate or nickel acetate solution. 16. The method according to claim 10, characterized in that the freshly anodized aluminum surface exposed to an aqueous manganese salt solution, preferably a manganese nitrate or manganese acetate solution will. 17. The method according to claim 9, characterized in that the freshly anodized aluminum surface a first solution containing chromium salts and lead salts is exposed to that subsequently rinsed and the surface is dipped in a second solution, the sodium carbonate or ammonium carbonate which forms insoluble salts with lead and chromium ions, which precipitate in the micropores. 18. The method according to claim 17, characterized in that the treatment with the first and second solution is repeated several times. 19. The method according to claim 17 or 18, characterized in that a compaction by It is boiled with water.