EP3571335A1

EP3571335A1 - Method for producing corrosion-stable and optionally colour/metallically coated and decorative plastic components

Info

Publication number: EP3571335A1
Application number: EP18703234.7A
Authority: EP
Inventors: Dirk Kieslich
Original assignee: Gerhardi Kunststofftechnik GmbH
Current assignee: Gerhardi Kunststofftechnik GmbH
Priority date: 2017-01-23
Filing date: 2018-01-23
Publication date: 2019-11-27
Also published as: CN110382746A; WO2018134436A1; DE202017000347U1; US20190345611A1

Abstract

The invention relates to a method for producing corrosion-stable and optionally colour/metallically coated, decorative plastic components (h), in which the components to be coated are first produced by the plastics injection-moulding process (a) from an electroplatable plastic and are subsequently subjected to a chemical pretreatment (b), in which a first conducting metal layer (c) is deposited and an aluminium is subsequently electrodeposited (e). The deposited aluminium surface is oxidized in a subsequent anodizing process (f).

Description

PROCESS FOR PRODUCING CORROSION STABILIZERS AND OPTIONAL COLOR METALLIC COATINGS, AND DECORATIVE

PLASTIC PARTS

The invention relates to a method for producing corrosion-resistant and optionally color-coated metallic decorative plastic components, wherein the components to be coated are first produced by plastic injection molding of a galvanisable plastic and then subjected to a chemical pretreatment, in which a first conductive metal layer is deposited and then an aluminum is deposited galvanically.

In the automotive industry, different and differently decorated plastic components are used for visual enhancement. Conventional surface technologies of such surface-decorated components are the manufacture of plastic surfaces by injection molding, painting of the plastic surfaces, scarring and etching of the tool surfaces to be imaged and molding them by plastic injection molding, galvanizing the plastic surface, decorating in the injection mold by IMD (In Mold Decoration), wherein an imprinted on a carrier film printing in the injection molding of a

Carrier film is molded, the injection molding of printed and partially deformed and contour-punched film inserts by the FIM technology, the film insert molding, and the metal foil back-injection.

In addition to all these classic surface technologies, the presentation of metallic surfaces is in particularly high demand in the trend, since this surface, like no other, suggests a high quality and robust appearance. In addition to the components decorated with real metal, ie veneered, joined or back-injected components with thin stainless steel or aluminum sheets, it is also particularly preferable to use metal-coated plastic components as decorative elements.

A coating method with which it is possible to achieve optically metallic surfaces is, for example, the vapor deposition, to which the PVD method (Physical Vapor Deposition) and their modified technologies such as CVD (Chemical Vapor Deposition) and PeCVD (plasma vapor deposition). Enhanced Chemical Vapor Desposition) and others belong. Here, thin metal layers are deposited in an evacuated vacuum chamber on a plastic component. The material to be deposited is in solid form. The vaporized material moves through the coating chamber and strikes the component to be coated, where precipitation leads to layer formation. Although the PVD process is generally suitable for representing metallic layers, it has proven to be problematic that the very thin metal coating can not have sufficient resistance to abrasion and corrosion without an additional protective layer. For this reason, it is necessary to apply a protective layer, for example a clearcoat system. In order to achieve a sufficient basic adhesion to the plastic component to be deposited, a coating of a primer is usually necessary. Another important and industrially important coating is the galvanic deposition of metals on plastic components. The parts are first produced by injection molding, for example from butadienhaitigen copolymers such as ABS or ABS / PC. After the injection molding process, the components are chemically pretreated to autoclaltically deposit on them a first thin metal layer, usually a thin layer of nickel or copper. In the further galvanic process, further metal layers are then deposited electrolytically until finally the electroplating process is finished, usually with a deposited chromium layer. For all surfaces used, in addition to the high aesthetic standards, there must also be a high resistance to mechanical damage as well as high media resistance in order to meet the later requirements of automotive exterior and interior design.

In addition to all these requirements, however, there is always the desire for more individuality, for design-technical freedom as well as color and structural design of the surfaces. Particularly in the case of metallic surfaces such as galvanic coating, the automotive industry often wishes color flexibility, but has hitherto been severely restricted in this presentation.

The conventional electrodeposited surface finishes and colors usually range from high gloss to different mattness, through to modified electrolytes and processes, to slightly anthracite and brownish tones.

Visual and tactile metallic and colored surfaces are usually possible only by autendige additional coatings or any additional coating on the metal deposition _"the adhesion of the coating films or the coating on the chromium layer has to be viewed critically always and the optical and haptic impression of the ground surface severely restricted becomes. This is due to the fact that the deposited chromium layer is very inert and inactive and therefore does not hold the (paint) layers.

For example, at high expense, a combination of lacquer, gas phase deposition, for example a PVD coating, and a tinted, ie weakly pigmented lacquer, can be used to display colored metallic surfaces. Such a technology is described in DE 102 33 120 A1. It is also possible to deposit the metal layers to be deposited directly on the substrate via special metal alloys. EP 2 369 032 A1 describes such an approach. But here is one as well Primer for bonding and a downstream, namely a Klariackierung necessary. However, the color spectrum is limited and the haptic sensation is reduced by the lacquer layer. The invention aims to remedy this situation. The invention has for its object to provide a method for producing corrosion-resistant and optionally color-coated metallic, decorative plastic components, in which a high-quality, corrosion-stable and optional inked decorative metal layer can be formed with a chemical and galvanic pretreatment and at least one galvanic metal deposition ,

This object is achieved by a method having the features of claim 1. Thereafter, the deposited aluminum surface is oxidized in a subsequent anodizing process.

The invention provides a process for producing corrosion-resistant and optionally metallic-color-coated, decorative plastic components, in which a high-quality, corrosion-resistant and optionally color-capable decorative metal layer can be formed by chemical and galvanic pretreatment and at least one galvanic metal deposition.

Preferably, the chemical pretreatment is performed by means of selected mechanical and chemical roughening, swelling and pickling technologies and other technologies for providing a first conductive metal layer adhesion mechanism. This makes it possible to dispense with the classical pretreatment process and to use other pretreatment methods. It has been found that adhesion is also obtained by blasting, treating with swelling and pickling acids above the chromic acid (classical), applying a first conductive layer by PVD or even blending conductive pigments, to build and deposit them to image a first conductive layer. In an embodiment of the invention, the anodized layer is compacted. During compaction, the pores opened by anodizing are closed again. This prevents the storage of corrosive substances.

Other developments and refinements of the invention are specified in the remaining subclaims. An embodiment of the invention is illustrated in the drawing and will be described in detail below. Show it:

Figure 1 shows the flow diagram of the method according to the invention

For this purpose, the components to be coated are first produced in the plastic injection molding process (a) from a galvanisable plastic, preferably from a butadiene-containing copolymenate such as ABS or ABS / PC. After the injection molding process, the components are chemically pretreated in a conventional plastic electroplating process (b) to subsequently autocally deposit a first thin metal layer on this machined surface (c), which is usually a thin layer of nickel or copper. Autocatalysis (Greek for "self-dissolution") refers to a special form of catalytic chemical reaction in which a final product acts as a catalyst for the reaction, and the continuous formation of this catalyst constantly accelerates the reaction.

In the further electroplating process, at least one metal layer is then applied electrolytically (d) or aluminum is deposited directly in a further galvanic process step (e), which is oxidized to an aluminum oxide in a subsequent anodization process (f) and optionally dyed (g). ,

The inventive method is thus according to the described process steps capable of corrosion-resistant and optionally colored metallic coated decorative plastic components provide (h). In the galvanic process step following the chemical pretreatment, an aluminum is deposited which, in the downstream anodization process, is oxidized to an aluminum oxide and optionally dyed.

The aluminum is also electrodeposited from electrolytes or from aluminum salts in organic solutions as well as optionally by ionic liquids. The method according to the invention can thus according to the method form a corrosion-resistant, optionally colored and decorative metallic surface coating on plastic components.

The described anodizing process uses, like the previously described galvanic process, the plastic electroplating of the electrolysis, the oxidation of the aluminum to aluminum (III) oxide generally being carried out under direct current at the anode. The converted aluminum oxide layer is subsequently highly corrosion-resistant and has a high visual appearance.

Before the anodizing process, the aluminum-coated components are usually degreased and pickled to remove impurities, deposits and possibly formed oxide layers. In pickling, existing small surface defects such as e.g. Scores, scratches, blowholes, inclusions, etc. eliminated by material removal.

After anodizing, the aluminum-coated component can be immersed in hot dye solution and then rinsed. When dyeing by this method, the dye moieties are deposited mainly in the upper regions of the pores of the anodized layer and enter into bonds with the oxide layer.

Using inorganic dyes, dyeing of the oxidized aluminum layers may also be performed. For this purpose, the component is neutralized after anodizing, rinsed and in color baths with Colored metal salt solutions. The ions of the solution accumulate in the pores of the anodizing layer and become a solid.

Another possibility of dyeing is the electrolytic Colinalverfah- ren, which is carried out with AC voltage. The electrolyte contains a coloring metal salt. The metal ions penetrate deeply into the pores of the layer. The pores, which are partly filled with metal, then cause a lightfast coloration due to their absorption and scattering effects. Many different shades are achievable. The duration of the electrolysis depends on the desired color depth.

Particularly attractive optical results are obtained in the so-called interference dyeing, in which, in contrast to the previous dyeing technologies, the color of the aluminum is not generated by embedded foreign ions, but by an interference within the aluminum oxide layer. In this case, light appears on thin layers of optically transparent materials such. As an oil film on water or as in soap bubbles is reflected, often colored. This color effect is also referred to as "iridescent colors" as a result of the refraction and interference of light on thin surface layers of an object, so that the object shines in the colors of the rainbow.The colors depend on the viewing angle, depending on the layer thickness of the oxide layer and the associated deletion of light, different colors (eg blue, green, gray or red) can be reproducibly displayed.

To prevent the accumulation of corrosive substances and to permanently seal the paint, the pores must be compacted. The anodized and possibly colored aluminum is compacted in a final processing step in demineralized water by simple cooking. Here, cooking in hot to boiling water can be used. On the one hand, this can be done by dip dyeing (adsorptive dyeing) at temperatures between 55 and 85 ° C., whereby the process can take between 15 to 30 minutes to 20 to 35 minutes. The re-compaction can also take place in the post-compressor solution at a temperature between 90 and 100 ° C. Approx. 3 minutes are required per 1 μm layer thickness for this treatment. Alternatively, the treatment can be done in hot water, which must be deionized water. The temperature is also between 90 and 100 ° C, for a 1 micron layer thickness also a duration of 3 minutes is required.

Claims

Claims 1. Process for the production of corrosion-resistant and optionally color-coated metallic decorative plastic components (h), in which the components to be coated are first produced in a plastic injection molding process (a) from a galvanisable plastic and then subjected to a chemical pretreatment (b), wherein a first conductive Metal layer (c) is deposited and then an aluminum is deposited by electrodeposition (e), characterized in that the deposited aluminum surface is oxidized in a subsequent anodization process (f).

2. The method according to claim 1, characterized in that the chemical pretreatment (b) is carried out according to a conventional plastic electroplating with the following processes:

Pickling with oxidative metal salt solutions for roughening the surface,

• Activate with metal germs, eg. B. palladium, as well

• autocatalytically occurring chemical metallization (c) to form a first conductive layer of copper, nickel or another metal.

A method according to claim 1, characterized in that the chemical pretreatment (b) is performed according to selected mechanical and chemical roughening, swelling and pickling technologies and other technologies for providing a first conductive metal layer adhesion mechanism.

4. The method according to any one of the preceding claims, characterized in that at least one metal layer is deposited on the pretreated components in a subsequent first electrolytic electroplating process (d) on which aluminum is deposited in a further process step (e).

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

6. The method according to any one of the preceding claims, character- ized in that on the derat pretreated components in an electrolytic Gaivanikprozess directly aluminum is deposited (e).

7. The method according to any one of the preceding claims, character- ized in that oxidized in a subsequent anodization process, the deposited aluminum to an aluminum oxide (f).

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

9. The method according to any one of the preceding claims, characterized in that the anodized layer is compacted.