METHOD FOR PRODUCING CORROSION-STABLE AND OPTIONALLY COLOUR/METALLICALLY COATED AND DECORATIVE PLASTIC COMPONENTS

Abstract

A method for the manufacture of plastic components that are corrosion-stable, optionally coated in metallic color and decorative first manufactures the components to be coated from a galvanizable plastic in the plastic injection-molding process and then subjects them to a chemical pretreatment, in which a first conductive metal layer is deposited and then an aluminum surface is deposited galvanically. The deposited aluminum surface is oxidized in a subsequent aluminum anodization process.

Claims

1. A method for the manufacture of plastic components that are corrosion-stable, optionally coated in metallic color and decorative (h), in which the components to be coated are first manufactured from a galvanizable plastic in the plastic injection-molding process (a) and are then subjected to a chemical pretreatment (b), in which a first conductive metal layer is deposited (c) and then an aluminum surface is deposited galvanically (e), wherein the deposited aluminum surface is oxidized in a subsequent aluminum anodization process (f), wherein the pores of the anodized layer are compacted by boiling in demineralized water.

2. The method according to claim 1, wherein the chemical pretreatment (b) is carried out according to a conventional plastic galvanization with the following processes: pickling with oxidative metal salt solutions for roughening of the surface, Activation with metal ions, e.g. palladium, as well as autocatalytically proceeding chemical metallization (c) for formation of a first conductive layer of copper, nickel or another metal.

3. The method according to claim 1, wherein the chemical pretreatment (b) is performed according to selected technologies with mechanical and chemical roughening, swelling and pickling and other technologies for providing an adhesion mechanism for a first conductive metal layer.

4. The method according to claim 1, wherein, in a subsequent first electrolytic galvanic process (d), at least one metal layer is applied on the pretreated components, on which metal layer aluminum is deposited in a further process step (e).

5. The method according to claim 4, wherein the aluminum is deposited in a galvanic process step.

6. The method according to one of the claim 1, wherein aluminum is deposited directly (e) in an electrolytic galvanic process on the components pretreated in such a way.

7. The method according to claim 1, wherein the deposited aluminum is oxidized to an aluminum oxide in a subsequent aluminum anodization process (f).

8. The method according to claim 7, wherein the aluminum layer oxidized to an aluminum oxide is colored (g).

9. (canceled)

Description

[0017] Other further developments and configurations of the invention are specified in the other dependent claims. An exemplary embodiment of the invention is illustrated in the drawing and will be described in detail in the following, wherein:

[0018] FIG. 1 shows the flow diagram of the method according to the invention

[0019] For this purpose, the components to be coated are first manufactured in the plastic injection-molding process (a) from a galvanized plastic, preferably from a butadiene-containing copolymer such as ABS or ABS/PC. After the injection-molding process, the components are chemically pretreated in a conventional plastic galvanic process (b), in order that a first thin metal layer, which is usually a thin nickel or copper layer, can be deposited on this machined surface autocatalytically (c). A special form of the catalytic chemical reaction, in which an end product acts as the catalyst for the reaction, is known as autocatalysis (Greek for self-dissolution). Due to the progressive formation of this catalysis, the reaction is steadily accelerated.

[0020] In the further galvanic process, at least one metal layer is applied galvanically (d) or aluminum is deposited directly in a further galvanic process step (e) and in a subsequent aluminum anodization process is oxidized to an aluminum oxide (f) and may optionally be colored (g).

[0021] In accordance with the described process steps, therefore, the method according to the invention is capable of preparing plastic components that are corrosion-stable, optionally coated in metallic color and decorative (h). In the galvanic process step following the chemical pretreatment, an aluminum is deposited, which in the subsequent aluminum anodization process may be oxidized to an aluminum oxide and optionally may be colored.

[0022] The aluminum is likewise deposited galvanically from electrolytes or from aluminum salts in organic solutions as well optionally by ionic liquids.

[0023] In accordance with the method, therefore, the method according to the invention is able to form, on plastic components, a metallic surface coating that is corrosion-stable, optionally colored and decorative.

[0024] The described aluminum anodization process is used just as the already described galvanic process of the plastic galvanization of the electrolysis, wherein oxidation of the aluminum to aluminum (III) oxide is usually performed at the anode using direct current. The transformed aluminum oxide layer is then highly corrosion-resistant and gives a high optical impression.

[0025] Prior to the aluminum anodization process, the aluminum-coated components are usually degreased and pickled, in order to remove contamination, deposits and oxide layers that may have been formed. During pickling, existing small surface flaws such as, for example, machining marks, scratches, blowholes, inclusions, etc. are eliminated by material removal.

[0026] After anodization, the aluminum-coated component may be dipped in hot dye solution and then rinsed. During coloring with this process, the dye molecules accumulate predominantly in the upper regions of the pores of the anodized aluminum layer and form bonds with the oxide layer.

[0027] A coloring of the oxidized aluminum layers may likewise be undertaken using organic dyes. For this purpose, after the anodization, the component is neutralized, rinsed and colored in dye baths containing metal salt solutions. The ions of the solution accumulate in the pores of the anodized aluminum layer and become a solid.

[0028] A further possibility for coloring is the electrolytic Colinal process, which is performed with alternating current. The electrolyte contains a color-imparting metal salt. The metal ions penetrate deep into the pores of the layer. The pores filled partly with metal in this way then cause a light-fast coloration due to absorption and scattering effects. Many different color shades are attainable. The duration of the electrolysis depends on the desired color depth.

[0029] Particularly appealing optical results are achieved in so-called interference coloring, in which, in contrast to the previous coloring technologies, the color of the aluminum is generated not by included foreign ions but instead by an interference within the aluminum oxide layer. In this situation, light that is reflected at thin layers of optically transparent materials, such as an oil film on water, for example, or as in soap bubbles, frequently appears to be colored. This colored effect is also known as iridescent colors, as a consequence of refraction and interference of the light at thin surface layers of an object. Thereby this object appears in the colors of the rainbow. The colors depend on the angle of view. Depending on layer thickness of the oxide layer and on the light extinction associated with it, different colors (e.g. blue, green, gray or red) may be simulated reproducibly.

[0030] In order to prevent the inclusion of corrosion-promoting substances, and in order to seal in the color permanently, the pores must be compacted. In a last machining step, the anodized and possibly colored aluminum is compacted in demineralized water by simple cooking. For this purpose it is possible to apply the cooking in hot to boiling water. This may take place by immersion coloring (adsorptive coloring) at temperatures between 55 and 85 C., wherein the process may last between 15 to 30 minutes up to 20 to 35 minutes.

[0031] The post-compaction may also take place in post-compaction solution at a temperature between 90 and 100 C. Approximately 3 minutes per 1 m of layer thickness is needed in this treatment. Alternatively, the treatment may take place in hot water, in which case the water must be de-ionized. The temperature is likewise between 90 and 100 C., wherein a duration of 3 minutes is likewise necessary for 1 m of layer thickness.