Method of coating a shaped polymeric body and apparatus for achieving a microstructured surface of a shaped polymeric body

Abstract

The invention relates to the field of chemistry and to a method for coating shaped polymer bodies, for example with various metals, and which can be used in automotive construction. It is an object of the invention to specify a method for coating shaped polymer bodies which is simpler and less costly and which achieves good adhesion and / or low surface roughness of the coating on the shaped polymer bodies. This object is achieved by a method in which the shaped polymer bodies consist at least partially of a thermoplastic having a filler level of at least 10% by mass and have been subjected to a pretreatment in a liquid consisting of at least one acid and one oxidizing agent, and in which, directly after this pretreatment and before the coating, the pretreated shaped polymer article is subjected to a treatment in at least one acid having at most 5 millimoles of oxidizing agent per liter of the at least one acid for at least 1 minute, and is subjected to an electroplating coating.

Description

Technical Field

[0001] This invention relates to the fields of chemical and mechanical engineering, and to a method for coating plastic molded bodies, and an apparatus for achieving microstructured surfaces of plastic molded bodies, such as those coated with various metals, which can be used in a variety of technical applications, such as in automotive engineering, in the electronics industry for example for high-frequency filters or high-frequency antennas, or in the jewelry industry. Background Technology

[0002] Metallization of plastic surfaces is typically carried out industrially via an electrochemical method after the molding process, by immersing the plastic molded part in an immersion bath of a salt solution of the metal to be applied. This bath also contains an anode or inert anode made of the metal to be applied. The metal is oxidized at the anode and enters the solution. During electrodeposition, metal ions are reduced on the plastic molded part to be coated, which is connected as a cathode. In this way, a metal deposit is deposited on the plastic molded part to be coated. Several layers of different or identical metals are typically applied. The reduction and oxidation reactions can be carried out by providing an electric current.

[0003] However, this method relies on the premise that the plastic molded part is conductive.

[0004] According to existing technology, the conductivity of metallized plastic molded parts is achieved after the molding process by applying metal salts, which are then reduced to metal cores or metal colloids. Typically, a first metal layer is applied to a surface, and then metallization is performed on that surface.

[0005] Metallization of plastic surfaces requires that the preforms and the first chemically applied metal layer adhere well to the surface of the plastic molded part under consideration. In the case of plastics, the hydrophobic surface of the plastic molded part must first be chemically modified to achieve good wetting by electrolytes.

[0006] Various methods for this purpose are known.

[0007] For example, DE 39 01 029 A1 specifies a method for metallizing molded articles made of polyarylene sulfides, wherein a non-corrosive glass oxidant is applied to the molded article prior to activation. The polyarylene sulfide used is a polyarylene sulfide containing 3%-40% polycarbonate or polyarylene ester, 2.5%-15% polyamide or polyester, and 2%-20% rubber elastomer, wherein Ti₂O₂ and MgCO₃ are excluded as fillers for the polycarbonate, polyarylene ester, polyamide, and polyester. Bromine solution, concentrated sulfuric acid, or chromium-containing sulfuric acid, or mixtures thereof with phosphoric acid or organic peracids, are used as oxidants.

[0008] Metallized molded articles and methods for producing them are also known from WO 2009 / 133751 A1. The metallized molded article has a coating of conductive polymer particles containing a binder formed on the surface of the molded article to be metallized, on which a metal layer is formed by electroless plating through the adsorption of a catalyst metal.

[0009] A method for pretreating the surface of a plastic part for electroplating is also known from EP 3 414 364 B1, wherein a plastic pretreatment impregnation solution having at least undissociated persulfate and undissociated sulfuric acid is prepared, and the plastic part to be coated is impregnated in the plastic pretreatment impregnation solution.

[0010] In all known pretreatments, the plastic is modified at least on its surface.

[0011] For example, ABS plastic is severely swollen on its surface by acid in a pretreatment device, forming a layer of approximately 1 μm. An oxidant in the pretreatment device can then penetrate the swollen plastic and oxidize the butadiene it contains. Due to the oxidation of the butadiene, it foams through gas generation, and the inorganic acid present in the pretreatment device can penetrate the foamed surface. This forms a microstructured surface on the ABS plastic.

[0012] Quite microstructured surfaces can also be achieved using molded bodies made from filled polyphenylene sulfide (PPS). In this case, the plastic matrix and, in some cases, the filler are oxidized or displaced by the oxidizing agent at different rates.

[0013] It is also known that on the surface of polyetherimide (PEI), after treatment with sulfuric acid and surface normalization with water, a white non-adhesive film exists on the surface, which has a particulate nature and is composed of oxidized PEI (Bradley R. Karas et al.: J. of Adhesion Science and Technology, (1992), 6:7, 815-828).

[0014] The following fact also prevents the metal coating from adhering well to the residues of the oxidized polymer on such microstructured surfaces: these residues are not completely removed by surface normalization or rinsing with water; in particular, the remaining relatively irregular size and distribution of the residues are re-cured by subsequent routine rinsing treatments and are not completely removed from the surface by subsequent cleaning treatments.

[0015] Therefore, these residues typically separate from the metal coating during subsequent metallization, resulting in incomplete metallization of the surface.

[0016] To achieve improved adhesion and metallization of PPS surfaces in these cases, EP 0 435 212 A1 describes a method for pretreating a metal coating on a molded body made of resin containing polyphenylene sulfide resin, a glass-based reinforcing filler, and optionally one or more other thermoplastic resins as its main components. In this method, the resin molded body is first immersed in an oxidizing acid solution, then in a liquid containing an organic polar solvent, and subsequently in a solvent dissolving the glass reinforcing filler and the thermoplastic resin. Hydrogen peroxide and sulfuric acid can be used as the oxidizing acid solution, N-methylpyrrolidone or dimethylacetamide can be used as the organic polar solvent, and sulfuric acid and / or alkaline aqueous solutions can be used as the solvent.

[0017] The drawback of known solutions remains insufficient adhesive strength of the coating on the plastic molded body, or the need for numerous and / or complex process steps to improve adhesive strength before coating the plastic molded body. Another disadvantage is the high surface roughness of the plastic molded body after coating.

[0018] Another drawback is the use of organic solvents, which requires extensive explosion protection in addition to occupational safety measures in large immersion baths. Summary of the Invention

[0019] The object of the present invention is to provide a method for coating plastic molded articles that is simpler and less costly and achieves good adhesion and / or low surface roughness of the coating on the plastic molded articles; and to provide an apparatus for achieving a microstructured surface of the plastic molded articles, which achieves hydrophilicity and a microstructured surface of the plastic molded articles prior to chemical and / or electroplating coating.

[0020] This objective is achieved by the invention as specified in the claims. Advantageous embodiments are the subject of the dependent claims, which may be, individually or in combination with, advantageous embodiments of the independent claims.

[0021] In the method for coating plastic profiles according to the invention, a plastic molded body, which is at least partially composed of at least 10% by mass of thermoplastic material and has been pretreated in a liquid consisting of at least one acid and an oxidant, is subjected to treatment in at least one acid for at least 1 minute immediately after the pretreatment of the plastic molded body and before coating, the at least one acid having a maximum of 5 millimoles of oxidant per liter of at least one acid, and then the treated plastic molded body is rinsed and / or cleaned and chemically and / or electroplated.

[0022] Advantageously, a plastic molded body composed of one or more thermoplastic materials filled to 20% to 80% by weight is used.

[0023] Polyphenylene sulfide, polyoxymethylene or polyetheretherketone are also advantageously used as thermoplastics.

[0024] Further advantageously, plastic molded bodies with inorganic fillers, advantageously inorganic salts, such as carbonates and / or sulfates and / or chlorides, are used.

[0025] Advantageously, a plastic molded body filled with calcium carbonate, calcium sulfate, magnesium carbonate or dolomite, consisting at least in part of polyphenylene sulfide, polyoxymethylene or polyetheretherketone, is also used.

[0026] It is also advantageous to use plastic molded bodies whose fillers are in the form of granules, fibers, spheres and / or geometric shapes.

[0027] It is also advantageous to pretreat the plastic molded parts using a liquid consisting of concentrated sulfuric acid, water, and persulfate as an oxidizing agent.

[0028] It is also advantageous to use precursors that form oxidants in situ during the pretreatment of the plastic molded body.

[0029] Furthermore, it is also advantageous to treat the pretreated plastic molded body with an inorganic acid or acid mixture used during the pretreatment process, wherein the inorganic acid (which is also advantageously concentrated sulfuric acid) remains advantageous for both the pretreatment and the acid treatment of the plastic molded body.

[0030] It is also advantageous if the pretreated plastic molded body is treated in at least one acid for 1 to 30 minutes.

[0031] It is also advantageous to rinse and / or clean the plastic molded body one to five times after treatment in at least one acid.

[0032] It is also advantageous to chemically or electroplat the plastic molded body after treatment in at least one acid, with or without rinsing and / or cleaning steps.

[0033] It is also advantageous to apply mechanical stress to the pretreatment liquid via ultrasound, agitation, flow, or turbulence during the pretreatment of the plastic molded body, or to move the plastic molded body in the pretreatment liquid.

[0034] It is also advantageous to apply mechanical stress to the acid by means of ultrasound, stirring, flow, or turbulence, or to move the plastic molded body in the acid during the treatment of the plastic molded body in at least one acid.

[0035] The apparatus according to the invention for coating a plastic molded body after pretreatment and for coating the plastic molded body directly after subsequent treatment to achieve a microstructured surface of the plastic molded body consists of at least an oxidant-free acid, wherein oxidant-free means that there are at most 5 millimoles of oxidant per liter of acid.

[0036] This invention provides for the first time a simple and cost-effective method for coating plastic molded bodies, which achieves good adhesion and / or low surface roughness of the coating on the plastic molded body; and an apparatus for achieving a microstructured surface of the plastic molded body, which achieves hydrophilicity and a microstructured surface of the plastic molded body.

[0037] This is achieved by a method according to the invention for coating plastic molded articles. This can be used to coat plastic molded articles that are at least partially composed of a thermoplastic material filled to at least 10% by weight.

[0038] Such plastic molded articles can advantageously consist of one or more thermoplastic materials filled to 20% to 80% by weight.

[0039] Polyphenylene sulfide, polyoxymethylene or polyetheretherketone are advantageously used as thermoplastics.

[0040] Thermoplastics that differ in type of plastic or even in variations of the same type of plastic from different manufacturers (often due to minor differences in manufacturing processes) can also be used.

[0041] Advantageously, thermoplastic molded articles are used with inorganic fillers, or even more advantageously inorganic salts such as carbonates and / or sulfates and / or chlorides as fillers.

[0042] A particularly advantageous aspect of the method according to the invention is a plastic molded body filled with calcium carbonate, calcium sulfate, magnesium carbonate, or dolomite, consisting at least in part of polyphenylene sulfide, polyoxymethylene, or polyetheretherketone.

[0043] Advantageously, fillers are used in thermoplastic molded bodies, which are in the form of particles, fibers, spheres and / or geometric shapes.

[0044] The plastic molded body used according to the invention is pretreated in a liquid consisting of at least one acid and at least one oxidizing agent, wherein the oxidizing agent must be able to oxidize the plastic at least on and near the surface, and advantageously also oxidize the filler on and near the surface.

[0045] The pretreatment parameters used for the plastic molded body can also be adapted to different types of plastics or to variations of the same type of plastic from different manufacturers.

[0046] The acid used in the pretreatment must also be able to dissolve at least the oxidized plastic parts, and, if necessary, dissolve the oxidized filler from the surface. Advantageously, inorganic acids are used as the acid.

[0047] Fillers on the surface of thermoplastics can be removed, at least partially, by means of acids and / or oxidizing agents, but also by other means or by mechanical or thermal methods.

[0048] Advantageously, the pretreatment of the plastic molded body can be carried out in a liquid containing an oxidizing agent such as persulfate in addition to sulfuric acid. Both the acid and the oxidizing agent can advantageously be used partially or entirely in their undissociated form.

[0049] Even more advantageously, a liquid consisting of concentrated sulfuric acid, water, and a peroxide compound as an oxidant is used for the pretreatment of the plastic molded articles. Their precursors can also be used with the peroxide compound, which is then formed in situ during the pretreatment of the plastic molded articles.

[0050] During this pretreatment of plastic molded parts, the presence of oxidation means causes the thermoplastic material itself to be at least partially oxidized on the surface and near the surface, typically to a depth of several micrometers.

[0051] The filler can also be oxidized.

[0052] However, fillers in plastic molded parts will, and in any case should, dissolve from the plastic composite at and near the surface, thereby creating depressions in the plastic surface. These depressions form a microstructured surface of the plastic molded part and help to achieve and / or improve the adhesion of metallization.

[0053] However, during the pretreatment of plastic molded parts, oxidized and / or dissolved fillers and plastics are only partially removed from the surface. After the pretreatment of the plastic molded parts, relatively irregularly sized and irregularly distributed residues of oxidized plastics and fillers remain on the surface of the plastic molded parts.

[0054] To remove these residues, according to the invention, treatment in at least one acid for at least 1 minute is performed directly after the pretreatment of the plastic molded part. According to the invention, this treatment must be carried out in at least one acid that does not contain an oxidizing agent.

[0055] Following this treatment, cleaning and surface standardization steps or further process steps can be performed before coating the plastic molded parts.

[0056] According to the present invention, "free of oxidants" means that the amount of oxidant in the at least one acid is at most 5 mmol / L.

[0057] Advantageously, the amount of oxidant in the at least one acid is from 0 mmol / L to 3 mmol / L, and particularly advantageously from 0 mmol / L to 1 mmol / L.

[0058] According to the present invention, the oxidant is neither added to the at least one acid as an oxidant nor introduced into the at least one acid as a precursor of the oxidant, such that the oxidant cannot be formed in situ in the at least one acid at a concentration higher than 5 mmol per liter of the at least one acid. However, the oxidant can be introduced due to technical implementation and / or by introduction of the oxidant through previous processing steps.

[0059] If an acid with oxidizing properties is used in the pretreatment steps before coating, then these acids should not be used, or only a small amount of acid should be used, or an acid with only a slight oxidizing effect on the plastic should be used.

[0060] Of particular importance to the method of the invention according to the present invention is that the treatment, which occurs directly after pretreatment and before coating, substantially completely removes relatively irregular and large and irregularly distributed residues of oxidized plastic and possibly oxidized filler from the surface of the plastic molded part, and the thus cleaned and microstructured surface of the plastic molded part can be provided with a coating that adheres well.

[0061] To improve the oxidation of thermoplastics and / or fillers, it is advantageous to apply mechanical stress to the pretreatment liquid by means of ultrasound, agitation, flow, or turbulence during the pretreatment of the plastic molded body, or to move the plastic molded body in the pretreatment liquid.

[0062] It is particularly advantageous to apply mechanical stress to the acid in the absence of an oxidant by means of ultrasound, stirring, flow, or turbulence during the treatment of the plastic molded body in at least one acid, or to move the plastic molded body in the acid in the absence of an oxidant.

[0063] In cases where the plastic is re-oxidized or further oxidized during the pre-coating treatment steps due to the oxidizing effect of the acid used, the plastic molded body can be repeatedly treated in at least one acid without an oxidizing agent according to the invention, thereby removing the oxidized plastic substantially completely from the surface of the plastic molded body again in any case.

[0064] Of particular importance to this invention is that no process steps, especially those for cleaning, rinsing, and / or surface standardization, are performed between the pretreatment of the plastic molded body and the treatment with at least one acid according to the invention, to exclude oxidants. Since the existing irregular and irregularly distributed residues of the oxidized plastic are essentially completely removed, the acid used for the treatment according to the invention is also not contaminated.

[0065] Furthermore, according to the invention, the pretreatment and treatment are carried out in at least one acid free of oxidants, using the same acid in each case, advantageously an inorganic acid. This further eliminates further contamination.

[0066] Advantageously, the pretreated plastic molded body is subjected to treatment in at least one acid in the absence of an oxidizing agent for 1 to 30 minutes.

[0067] After a plastic molded body is treated with at least one acid in the absence of an oxidant, the plastic molded body treated in this way is rinsed and / or cleaned, activated with a catalyst, and chemically coated, i.e. without an external current, and optionally electroplated afterwards.

[0068] The number and length of rinsing and cleaning steps correspond to those of known existing technologies.

[0069] Chemical and electroplating coatings are also carried out using existing technical methods.

[0070] The method according to the invention substantially completely removes relatively irregularly sized and irregularly distributed residues of oxidized material from the surface of the plastic molded body, which were more or less firmly adhered to the surface of the plastic during the pretreatment of the plastic molded body. For subsequent chemical and / or electroplating coatings, this means achieving complete and well-adhered metallization of the plastic molded body surface, as well as a smooth metallized surface.

[0071] Furthermore, this objective is achieved by a device for realizing a microstructured surface of the plastic molded body, which realizes the microstructured surface of the plastic molded body before coating.

[0072] This is achieved by a device for creating a microstructured surface of the plastic molded body after pretreatment and for coating the surface of the plastic molded body directly after subsequent treatment, the device consisting of at least one acid that is free of oxidants, wherein free of oxidants means that there are at most 5 millimoles of oxidant per liter of acid.

[0073] Advantageously, at least one inorganic acid is present.

[0074] Furthermore, for the apparatus according to the invention, "free of oxidant" also means that the amount of oxidant in the at least one acid is at most 5 mmol / L, advantageously from 0 mmol / L to 3 mmol / L, and particularly advantageously from 0 mmol / L to 1 mmol / L.

[0075] According to the present invention, the apparatus may contain up to 5 mmol / L due to the technical implementation of the method and / or due to the introduction of an oxidant from a previous processing step.

[0076] Using the apparatus according to the invention for achieving a microstructured surface of a plastic molded article prior to coating, after pretreatment and before coating, irregularly large and irregularly distributed residues of oxidized material on and near the surface of the pretreated plastic molded article are removed from the surface of the plastic molded article. Simultaneously, fillers still present on and near the surface of the plastic molded article are at least partially dissolved and may also be at least partially oxidized and / or removed. By at least partially removing fillers from the plastic composite, a microstructured surface is produced, which significantly improves the adhesion of subsequently applied coatings. Detailed Implementation

[0077] The invention is described in more detail below using several embodiments of the implementation plan.

[0078] Refer to Example 1

[0079] Coatings of plastic molded articles not treated in at least one acid without oxidizing agent

[0080] The coating was applied to three plastic molded bodies, which were injection-molded sheets made of Toray's PPS (Torelina A310MB6) thermoplastic with a filler content of 65% by weight, consisting of glass fiber and mineral particles. The sheets were 80mm × 80mm in size and 3mm thick.

[0081] First, the plates were cleaned and degreased for pretreatment, and then dried. A mixture of sulfuric acid and hydrogen peroxide was prepared as the pickling solution for pretreatment, yielding 78% sulfuric acid with a total oxidant content of 35 mM (millimoles). The plates were exposed to the pickling solution for 2.5 minutes.

[0082] The pretreated board is then immediately subjected to chemical electroplating in various immersion baths, wherein, according to existing techniques for chemical electroplating processes, it is rinsed with water three times between each immersion bath: Immersion bath: 1. Expose to the activator UDIQUE 879 (MacDermid Enthone) at 32°C for 4 minutes. 2. Expose to the accelerator UDIQUE 8810 (MacDermid Enthone) at 45°C for 4 minutes. 3. Expose in electroless nickel plating UDIQUE 891 (MacDermid Enthone) at 32°C and pH 8.9 for 7.5 minutes.

[0083] Following this treatment, a closed conductive nickel layer exists across the entire surface of the board, which is then treated with a Cuprostar (MacDermid Enthone) copper bath at room temperature and 4.0 A / dm². 2 A copper layer with a thickness of 40 μm was added to it at a current density and left for 45 minutes.

[0084] The plates are then pre-dried in a stream of hot air and stored for 24 hours for final drying.

[0085] To measure the adhesive strength, after drying, the copper layer on the panel was cut at a distance of one centimeter with a saw, and the resulting copper strip, 1 cm in length, was removed from the component and clamped in a Mecmesin Multitest 2.5i material testing machine to measure the peel strength according to DIN EN 1464. The strip was pulled out at a speed of 50 mm / s and at a 90° angle.

[0086] The measurement results show that the pull-out force of the plate is between 2.9 N / cm and 3.7 N / cm.

[0087] The nickel- and copper-coated plates exhibited visible roughness at various macroscopic locations. Surface roughness was measured using a surface roughness tester (YRT100) at a measurement distance of 0.8 mm before and after plate treatment, and the following values ​​were obtained:

[0088] These values ​​show that the initial surface roughness of the plastic sheet has increased significantly due to the treatment.

[0089] Example 2

[0090] As in Example 1, the method is performed on three plastic molded bodies after pretreatment. These plastic molded bodies are in the form of injection-molded sheets made of Toray's PPS (Torelina A310MB6), a thermoplastic material in which glass fiber and mineral particles are present as fillers at a content of 65% by weight. The sheets are also 80mm × 80mm in size and 3mm thick.

[0091] First, the plate was cleaned and degreased, then dried. A mixture of sulfuric acid and hydrogen peroxide was prepared as an oxidant for pretreatment pickling, yielding 78% sulfuric acid with a total oxidant content of 35 mM. The plate was exposed to the pickling solution for 2.5 minutes.

[0092] Although injection-molded sheets made of PPS are very hydrophobic with a contact angle of 120° before pretreatment, their surfaces become hydrophilic after pretreatment, and the contact angle approaches 0°.

[0093] However, remnants of oxidized material are still visually visible on the plastic surface.

[0094] Therefore, directly after pretreatment, the injection molded sheet made of PPS as a plastic molded body is completely immersed in an acidic solution that does not contain oxidants. This solution consists of 78% sulfuric acid and 0.1 g / L of added surfactant sodium lauryl sulfate (SDS).

[0095] The total content of oxidant in the solution was determined by oxidation of an iron stock solution. For this purpose, an iron stock solution containing 19 g of ferric(II) sulfate and 1.5 g of ferric(II) ammonium sulfate was dissolved in 45 ml of deionized water, and the concentration was determined by titration with potassium permanganate. 2 ml of this iron stock solution was added to a mixture of 50 ml of deionized water and 1 ml of the test solution, and the concentration was determined again by titration with potassium permanganate. During this process, the decrease in Fe2+ ions due to the addition of the test solution corresponded to twice the value of the oxidant content.

[0096] The measurement results show a value of 0.8 millimoles per liter of oxidant.

[0097] To mechanically enhance surface cleaning, the solution containing the plate was placed in a water-filled laboratory ultrasonic unit (Bandelin Sonorex RK100) and ultrasonically treated at 80 watts during exposure. The sample was then rinsed with water at room temperature (20°C).

[0098] Following this treatment with acid in the absence of an oxidizing agent, the plastic molded body remains hydrophilic and possesses a microstructured surface. Residues of oxidized material that adhered to the plastic surface after the pretreatment step are now removed and no longer visible.

[0099] Further process steps for metal coating are performed according to Example 1.

[0100] The measured adhesive strength of the layer according to Example 1 was between 3.5 N / cm and 4.5 N / cm.

[0101] The coated board now has a more visually uniform appearance and very low roughness across its entire surface. Surface roughness was measured before and after treatment using the method described in Example 1, and the following values ​​were obtained:

[0102] These values ​​show that, compared to the reference embodiment, the initial surface roughness of the plastic sheet was reduced through the treatment.

[0103] Example 3

[0104] The coating was applied to three plastic profiles, which were injection-molded sheets made of polyphenylene sulfide (PPS) (black Xytron M5710T) from DSM, consisting of 57% by weight of glass fiber and mineral particles as filler. The sheets were 80mm x 80mm in size and 3mm thick.

[0105] First, the plate is cleaned and degreased, then dried. A mixture of sulfuric acid and hydrogen peroxide is prepared as an oxidizing agent as a pretreatment pickling solution, yielding 79.5% sulfuric acid with a total oxidizing agent content of 50 mM.

[0106] The pickling solution is heated to 40°C, and the plate is completely immersed in the pickling solution for 1.5 minutes.

[0107] Although injection-molded sheets made of PPS are very hydrophobic with a contact angle of 120° before pretreatment, their surfaces become hydrophilic after pretreatment, and the contact angle approaches 0°.

[0108] However, remnants of oxidized material are still visually visible on the plastic surface.

[0109] At the port, the plate is immediately and completely immersed in a bath of 80% sulfuric acid at a temperature of 40°C to treat it with acid in the absence of oxidizing agents.

[0110] To ensure optimal treatment, the process was interrupted for a few seconds every 2 minutes, for a total of three times, and the plates were removed from the bath. After exposing the plates to the bath for another four minutes, the plates were then rinsed in 60°C water for 10 minutes.

[0111] Following this treatment with acid in the absence of an oxidizing agent, the plastic molded body remains hydrophilic and possesses a microstructured surface. Residues of oxidized material adhering to the plastic surface are removed and no longer visible after the pretreatment step.

[0112] Further process steps for metal coating are performed as in Example 1, wherein in step 3, a nickel bath Enplate Ni-817 (MacDermid Enthone) with particularly high activity at pH 4.7 and 85°C is used, with the same exposure time of 7.5 minutes.

[0113] The measured adhesive strength of the layer according to Example 1 was between 3.5 N / cm and 4.0 N / cm.

[0114] Even on a macroscopic scale, the nickel and copper coated plates exhibit a uniform appearance and very low roughness across the entire surface. Surface roughness was measured before and after the plate treatment using the method described in Example 1, and the following values ​​were obtained.

[0115] These values ​​indicate that the treatment has reduced the initial surface roughness of the plastic sheet.

Claims

1. A method for coating a molded plastic body, wherein the molded plastic body is at least partially composed of at least 10% by mass of a thermoplastic material, the molded plastic body has been pretreated in a liquid consisting of at least one acid and an oxidizing agent, and immediately after the pretreatment and before coating, the pretreated molded plastic body is subjected to treatment in at least one acid for at least 1 minute, the at least one acid containing at most 5 millimoles of oxidizing agent per liter of at least one acid, followed by rinsing and / or cleaning of the molded plastic body treated in this manner and performing chemical coating and / or electroplating.

2. The method of claim 1, wherein a molded plastic body is used, comprising one or more thermoplastic materials filled to 20% to 80% by weight.

3. The method according to claim 1, wherein polyphenylene sulfide, polyoxymethylene, or polyetheretherketone is used as a thermoplastic polymer.

4. The method of claim 1, wherein a molded plastic body containing inorganic fillers, advantageously inorganic salts such as carbonates and / or sulfates and / or chlorides, is used.

5. The method of claim 1, wherein a molded plastic body filled with calcium carbonate, calcium sulfate, magnesium carbonate or dolomite is used, which is at least partially composed of polyphenylene sulfide or polyoxymethylene or polyetheretherketone.

6. The method of claim 1, wherein the filler used therein is a molded plastic body in the form of particles, fibers, spheres and / or geometric shapes.

7. The method according to claim 1, wherein a liquid consisting of concentrated sulfuric acid, water, and persulfate as an oxidant is used for the pretreatment of the molded plastic body.

8. The method of claim 1, wherein a precursor of an oxidant is used during the pretreatment of the molded plastic body to form an oxidant in situ.

9. The method of claim 1, wherein the inorganic acid or acid mixture used during the pretreatment is used for the treatment of the pretreated molded plastic body.

10. The method of claim 9, wherein an inorganic acid, preferably concentrated sulfuric acid, is used for the pretreatment of the molded plastic body and the treatment performed with acid.

11. The method of claim 1, wherein the pretreated molded plastic body is treated in at least one acid for 1 minute to 30 minutes.

12. The method of claim 1, wherein after the treatment in at least one acid, the molded plastic body is rinsed and / or cleaned one to five times.

13. The method of claim 1, wherein after the treatment in at least one acid, the molded plastic body is chemically coated or electroplated with or without rinsing and / or cleaning steps.

14. The method of claim 1, wherein during the pretreatment of the molded plastic body, mechanical stress is advantageously applied to the pretreatment liquid by means of ultrasound, stirring, flow, or turbulence, or the molded plastic body is moved in the pretreatment liquid.

15. The method of claim 1, wherein during the treatment of the molded plastic body in at least one acid, mechanical stress is advantageously applied to the acid by means of ultrasound, stirring, achieving flow, turbulence, or moving the molded plastic body in the acid.

16. An apparatus for coating a molded plastic body after pretreatment and for coating the molded plastic body directly after subsequent treatment to achieve a microstructured surface of the molded plastic body, said apparatus comprising at least an oxidant-free acid, wherein oxidant-free means having at most 5 millimoles of oxidant per liter of acid.

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