Method for etching a plastic substrate including spraying and electrolytic regeneration

Abstract

The present invention relates to a method for etching a plastic substrate including steps (A) to (C), wherein step (C) includes non-immersion dispensing of an acidic etching composition containing water and one or more manganese species. Further, the dispensed acidic etching composition is treated in a regeneration compartment for regeneration by application of an electric current and returned to the acidic etching composition.

Description

Technical Field

[0001] The present invention relates to a method for etching a plastic substrate including steps (A) to (C), wherein step (C) includes non-immersion dispensing of an acidic etching composition containing water and one or more manganese species. Further, the dispensed acidic etching composition is treated in a regeneration compartment for regeneration by applying an electric current and returned to the acidic etching composition.

Background Art

[0002] The metallization of non-metal substrates such as plastic substrates has a long history in modern technology. Typical applications are found not only in sanitary articles but also in the automotive industry.

[0003] However, it is demanding to make a plastic substrate receptive to a metal layer. Typically, each method basically starts with surface modification of the substrate surface, which is usually known as etching. Usually, a delicate balance is required to ensure sufficient roughening without causing over-etching.

[0004] Many methods and etching compositions are known that include compositions containing environmentally questionable chromium species such as hexavalent chromium species (e.g., chromic acid). These compositions usually provide very strong and acceptable etching results, but there is an increasing demand for environmentally friendly alternatives, which are already provided to some extent in the industry. In many cases, manganese-based etching compositions, especially permanganate-based etching compositions, are used instead, and they are attracting increasing attention in the market.

[0005] European Patent Application Publication No. 3 666 926 mentions a method of generating manganese(III) ions from manganese(II) ions in a mixed acidic aqueous solution of sulfuric acid and alkanesulfonic acid using ozone, and the production efficiency of manganese(III) ions from manganese(II) ions using ozone is at least 60%. Electrolytic regeneration is considered inconvenient.

[0006] Japanese Patent Application Laid-Open No. 2003-013244 mentions a method of depositing a catalyst for electroless plating on the surface of a resin substrate. The method is characterized by etching the surface of the resin substrate using an etching solution containing a Pd compound.

[0007] U.S. Patent No. 8,603,352 mentions a chromium-free composition of an acidic suspension of manganese compounds and manganese ions that is applied to the surface of an organic polymer to etch the surface.

[0008] European Patent Application Publication No. 2,657,367 mentions a pre-etching composition for treating a non-conductive substrate in a plating process for depositing a metal layer on a substrate surface.

[0009] Among those permanganate-based etching compositions, particularly alkaline permanganate-based etching compositions have been known for a quite long time. However, their etching ability is typically much more limited compared to acidic permanganate-based etching compositions that provide a more effective etching effect and are much more powerful. However, on the negative side, they have a major drawback that permanganate ions rapidly decompose in an acidic environment. For this reason, either a constant replenishment of unused permanganate ions or a certain recycling process for chemically or electrolytically reforming permanganate ions is required.

[0010] The above-mentioned requirements typically require high energy consumption, which is associated with a high CO2 footprint and / or intensive wastewater treatment during disposal, which is undesirable.

[0011] In particular, the constant electrolytic regeneration of manganese species, especially permanganic acid, constantly requires a large amount of energy consumption.

[0012] Therefore, it is an important requirement to provide an improved etching method that utilizes an acidic manganese-based etching composition with a reduced burden of maintaining the active manganese species, most preferably permanganate ions. Further, it is desirable to further reduce the environmental impact of such an etching composition. [[Prior Art Documents]] [[Patent Documents]]

[0013] [[Patent Document 1]] European Patent Application Publication No. 3,666,926 [[Patent Document 2]] Japanese Unexamined Patent Application Publication No. 2003-013244 [[Patent Document 3]] U.S. Patent No. 8,603,352 [[Patent Document 4]] European Patent Application Publication No. 2,657,367 [[Summary of the Invention]] [[Problems to be Solved by the Invention]]

[0014] Therefore, an object of the present invention is to provide a method for etching a plastic substrate, with a significantly reduced burden of maintaining active manganese species, resulting in reduced environmental impact and energy consumption, but without degrading the etching quality. [[Means for Solving the Problems]]

[0015] The above object is achieved by a method for etching a plastic substrate (1), (A) preparing an etching chamber (10) and a regeneration chamber (30); (B) placing the plastic substrate (1) in the etching chamber (10); (C) etching the plastic substrate (1) in the etching chamber (10) to obtain an etched plastic substrate, using (a) water, and (b) one or more manganese species Contacting with an acidic etching composition containing In a method comprising - The contacting in step (C) is non-immersion dispensing of the acidic etching composition onto the plastic substrate (1), resulting in a dispensed acidic etching composition, - At least a part of the dispensed acidic etching composition is treated in a regeneration compartment (30) by applying an electric current and returned to the acidic etching composition, which is characterized by the method.

[0016] The method of the present invention combines two basic features. First, instead of the ordinary immersion / dip / liquid immersion of the plastic substrate into each acidic etching composition, it is non-immersion dispensing of the acidic etching composition. Second, at least a part of the dispensed acidic etching composition is treated (i.e., reused and regenerated respectively) in the regeneration compartment and returned (i.e., replenished) to the acidic etching composition. This combination generally makes it possible to maintain the acidic etching composition in its active state for strongly desired and effective etching with a significantly reduced burden, including less energy and resource consumption.

[0017] Therefore, in the method of the present invention, the plastic substrate (1) is not immersed, flooded and / or dipped into the acidic etching composition. Instead, in the method of the present invention, the acidic etching composition is brought into active contact with the plastic substrate (i.e., by dispensing) instead of actively contacting the plastic substrate as in the case of ordinary immersion / dipping / flooding methods. Thus, in ordinary immersion / dipping / flooding methods, the etching composition is in a stationary state as an etching bath (i.e., confined by the storage tank walls), the plastic substrate is mobile and is lifted into the etching composition for etching, whereas in the method of the present invention, the plastic substrate is rather stationary and the acidic etching composition is in a mobile state. Also, in the context of the present invention, most preferably, the only etching is the etching as defined in step (C), i.e., as a result of dispensing the acidic etching composition. Preferably, no other etching of the plastic-based substrate is performed. In other words, the method of the present invention is preferably a one-step etching.

[0018] Those skilled in the art are aware that non-immersion dispensing has several disadvantages. Therefore, those skilled in the art did not consider non-immersion dispensing as an etching method. The disadvantages of non-immersion dispensing are well known to those skilled in the art: · Formation of aerosols by finely dispersed droplets · The technical burden is greater than immersion only · Energy requirements for solution transport and dispersion, and · Energy requirements for heating to compensate for the cooling effect caused by evaporation of water due to the large specific surface area of the formed droplets · Penetration into areas on the back side of the substrate such as holes, cavities and undercuts · Higher throughput for the same amount, and subsequent introduction of the solution, i.e., water and organics, before the processing step.

[0019] The list of disadvantages is not exhaustive.

[0020] The inventors have surprisingly found that the method of the present invention is advantageous over the prior art. Without wishing to be bound by a particular theory, it is believed that the recycling efforts brought about by the reduced amounts can be achieved without incurring the above disadvantages.

[0021] In particular, in the experiments, surprisingly, it was shown that depending on the selected applied pressure and the type of nozzle, there was little formation of finely dispersed droplets of the etchant. Aerosol measurements near the etchant bath showed no detectable aerosol. The results were below the detection limit. The acid discharged was typically less than 1 / 100 or even less of the limit, and the manganese discharged was typically less than 1 / 20 or even less of the limit.

[0022] Compared with ordinary immersion / dip / liquid immersion methods, non-immersion dispensing dramatically reduces the required amount of the acidic etching composition, so a significantly reduced total volume of the acidic etching composition has to be prepared for the whole method. This also has the major advantage that significantly reduced amounts have to be processed in each recycling compartment. This reduces the extent of the current (and other means for oxidation) required for recycling, as the total amount of manganese species to be decomposed is similarly significantly reduced. In a direct comparison, in our own examples, it has been shown that up to 80% of the electrical energy can be saved compared with an immersion / dip / liquid immersion method combined with electrolytic recycling as well.

[0023] Furthermore, such a significantly reduced total volume does not require such large amounts of chemicals and thus, for example, reduces the environmental impact during disposal. In addition, in our own experiments, several further advantages have been shown.

[0024] Compared with the dipping method, the non-dipping dispensing used in the present invention enables contact that can be selected both temporally and positionally. This means, for example, that the dispensing nozzle preferably operates and does not operate selectively. As a result, for example, the front side of the plastic substrate can be significantly etched, and the rear part is significantly omitted. This is, for example, (i) when the plastic substrate includes a relatively sophisticated surface geometry on the front that requires stronger etching compared to the rear that includes a less sophisticated surface geometry that does not require so strong etching, or (ii) when a two-component plastic substrate is etched and different materials are exposed on different sides, and one component requires stronger etching compared to the other component, which is advantageous. Further, the dispensing nozzle can be operated at specific time intervals and followed by non-operating time intervals. In other words, the dispensing pattern can be designed in terms of the requirements of the plastic substrate even without means for at least partially covering the surface of each plastic substrate.

[0025] Furthermore, compared with the dipping method, the non-dipping dispensing used in the present invention enables significantly improved temperature control of the acidic etching composition. Since decomposition is highly temperature-dependent, the acidic etching composition has a specific temperature ideally selected for optimal etching, but the temperature can be significantly reduced during processing in the regeneration compartment to minimize decomposition. Due to the fact that the total volume can be reduced by non-dipping dispensing, the respective volumes for heating and cooling are also less compared to the ordinary dipping method.

[0026] Surprisingly, it has been found that the higher evaporation of water in non-dipping dispensing is advantageous. It is concluded that the reduction in the water extraction amount is compensated by the reduction in the regeneration ability. As a result, the electrolyte is not diluted during operation and is cooled due to the evaporation effect. As a result, the cooling power can be significantly reduced or even completely removed due to this effect. This eliminates the need to incorporate a cooler altogether, or the size and capacity can be reduced, thus dramatically reducing the technical burden for electrolytic regeneration.

[0027] Furthermore, surprisingly, as compared to the dip method, the non-dip dispensing utilized in the present invention reduces etching defects and improves wetting. In fact, the dip method typically requires strong mixing and movement of the etching composition, respectively. This often leads to the formation of gas bubbles in the composition. Furthermore, side reactions, particularly decomposition processes, further form gas bubbles. When such gas bubbles adsorb to the surface of the plastic substrate, etching is severely impaired at these locations. In our own experiments, non-dip dispensing, particularly spraying, has been shown to significantly prevent such harmful effects. This is even more pronounced when the plastic substrate has a very delicate surface geometry. This most preferably includes that the plastic substrate is not contacted with any surfactant either in the step immediately preceding the etching step or during the etching step. This completely prevents the unwanted introduction of surfactants into the etching composition. If surfactants are present, it is believed that the surfactants are oxidized and not removed from the etching composition. As a result, they accumulate, and the accumulation of surfactants and oxidized surfactants increases the capacity requirements of the recycling device. Furthermore, water, which is associated with unwanted dilution and requires further separation measures and energy, is not introduced into the etchant.

Brief Description of the Drawings

[0028]

Figure 1

Embodiments for Carrying Out the Invention

[0029] Reference Signs 1, respectively, a plastic substrate and a plurality of plastic substrates 2 Rack 3 Vertical gas flow 10 Etching compartment 11 Opening equipped with a door 12 Multiple dispensing nozzles 13 Dispensing pipeline 14 Supply pipeline 15 Ventilation duct 16 Liquid separator 17 Pump 20 Reservoir 21 Inlet side regeneration pipeline 22 Outlet side regeneration pipeline 30 Regeneration compartment

[0030] Step (A): In step (A), an etching compartment (10) and a regeneration compartment (30) are provided.

[0031] The etching compartment (10) and the regeneration compartment (30) are separate and distinct compartments, and preferably, the method of the present invention that is spatially divided is preferred.

[0032] The etching compartment is a place where etching is performed, and the regeneration compartment is a place where regeneration is performed. Both compartments are preferably fluidly connected by a transfer pipeline for the transfer of the acidic etching composition and the dispensed acidic etching composition, respectively. Further details are given in the text below with respect to the more detailed description of the figures.

[0033] The etching compartment is preferably manufactured from a material resistant to the acidic etching composition or at least contains it. Preferred materials are one or more selected from the group consisting of fluoropolymer plastics, most preferably polyvinyl fluoride (PVF), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), and polychlorotrifluoroethylene (PCTFE), most preferably polyvinylidene fluoride (PVDF).

[0034] During step (C), the etching compartment contains a plastic substrate. To avoid the release of the dispensed acidic etching composition, the etching compartment is closed during step (C). This also includes that the etching compartment is highly airtight. Therefore, the method of the present invention in which the etching compartment includes an opening equipped with a door is preferred.

[0035] Typically, the plastic substrates preferably include a plurality of plastic substrates. In order to preferably etch such a plurality, they are fixed to a rack (in the sense of being temporarily coupled to the rack). Thus, the etching chamber preferably contains a rack during step (C), and the plastic substrates are fixed to the rack in the method of the present invention.

[0036] The method of the present invention is preferred in which the etching chamber (10) includes one or more dispensing nozzles (12) for non-immersion dispensing in step (C), preferably a plurality of dispensing nozzles, and most preferably a plurality of spray nozzles.

[0037] The etching chamber (10) has a total spray window area dm 2 per nozzle of 0.1 to 2, preferably 0.3 to 1.8, more preferably 0.5 to 1.6, still more preferably 0.7 to 1.4, and most preferably 0.9 to 1.3. This preferably applies to spray nozzles.

[0038] Typically, the plastic substrate and the plurality of plastic substrates each occupy a specific space within the etching chamber. Preferably, one or more dispensing nozzles are located around them, and most preferably, they are located on the sides with respect to the plastic substrate and the plurality of plastic substrates respectively. This space is typically characterized by a specific edge length in three dimensions (height, depth, width), thereby typically defining a cuboid. In the context of the present invention, the term "total spray window area" represents the total sum of the outer surface areas of this cuboid. The total spray window area is simply named "spray window" or "Warenfenster".

[0039] In some cases, the etching compartment (10) preferably contains from 5 to 1000 dispensing nozzles, more preferably from 10 to 600 dispensing nozzles, even more preferably from 30 to 400 dispensing nozzles, still even more preferably from 50 to 200 dispensing nozzles, and most preferably from 70 to 150 dispensing nozzles, according to the method of the present invention. This preferably refers to one individual etching compartment (when multiple are used).

[0040] In some cases, the etching compartment (10) preferably contains from 10 to 700 spray nozzles, preferably from 25 to 600 spray nozzles, more preferably from 40 to 500 spray nozzles, even more preferably from 50 to 400 spray nozzles, still even more preferably from 60 to 300 spray nozzles, and most preferably from 80 to 200 spray nozzles, according to the method of the present invention. This preferably refers to one individual etching compartment (when multiple are used). In this particular case, one or more dispensing nozzles are preferably one or more spray nozzles.

[0041] In the etching compartment (10), the method of the present invention in which one or more dispensing nozzles (12) are inert to the acidic etching composition is preferred.

[0042] In the etching compartment (10), the method of the present invention in which one or more dispensing nozzles (12) at least partially contain or consist entirely of fluoropolymer plastics, titanium, stainless steel, combinations and / or composites thereof is more preferred. Preferred fluoropolymer plastics are one or more selected from the group consisting of polyvinyl fluoride (PVF), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), and polychlorotrifluoroethylene (PCTFE), and most preferably polyvinylidene fluoride (PVDF).

[0043] In a separate experiment, it has been shown that the etching compartment need not be airtight to prevent any mist of the acidic etching composition from escaping (i.e., in the sense of leakage). Rather, the internal gas flow is in most cases sufficient to avoid this. Thus, in the etching compartment (10), the vertical gas flow (3) is preferably applied from the top to the bottom and the method of the present invention for transporting at least a part of the dispensed acidic etching composition is preferred. This very efficiently prevents leakage. Thus, the vertical gas flow preferably comprises at least a part of the dispensed acidic etching composition.

[0044] The vertical gas flow preferably comprises ambient air, most preferably the method of the present invention comprising ambient air and at least a part of the dispensed acidic etching composition. In some cases, it is preferred that the vertical gas flow contains or alternatively an inert protective gas, preferably nitrogen gas or noble gas, thereon.

[0045] The method of the present invention in which the vertical gas flow is applied at time intervals is more preferred. Generally, after the contact in step (C) has ended, even if the door of the opening is opened to take out the plastic substrate, preferably until the dispensed acidic etching composition can no longer escape, most preferably until substantially all of the dispensed acidic etching composition has been removed from the etching compartment, the method of the present invention in which the vertical gas flow is applied is preferred. This also preferably means that the vertical gas flow is applied during step (B) subsequently performed through the method of the present invention. During step (C), the vertical gas flow is either not applied (i.e., stopped) or applied using a reduced flow compared to the flow applied after the contact in step (B) and / or after step (C) has ended.

[0046] The use of a vertical gas flow is an important safety feature. As a result, a mixture of gas and a dispensed acidic etching composition is obtained. The etching compartment preferably comprises a ventilation duct (15) which draws off the vertical gas flow and which is connected to a liquid separator (16) which separates the liquid from the gas flow. This results in a separated liquid containing the dispensed acid etching composition in its liquid form, which is most preferably transferred to a reservoir (20).

[0047] The ventilation duct is preferably located at or near the bottom of the etching compartment according to the method of the invention.

[0048] In step (A), a regeneration compartment is also provided for regeneration. The regeneration is carried out by applying an electric current. Generally, the electric current oxidizes at least a part of one or more manganese species in the dispensed acidic etching composition, thereby regenerating (i.e. reusing) and resulting in the formation of an acidic etching composition which is ready to be reused again in step (C) for contacting. Most preferably, in the regeneration compartment, permanganate ions, i.e. manganese species having an oxidation number of +VII, are formed. This procedure is commonly named electrolytic reoxidation. In the context of the present invention, it is a great advantage of the electrolytic reoxidation that the total concentration of all manganese species remains relatively stable together. In fact, apart from replenishing the manganese species taken out, the manganese species are typically not added to maintain the method. This contributes to a relatively high process stability.

[0049] The regeneration is preferably according to the method of the invention which is not a regeneration without applying an electric current.

[0050] The regeneration preferably according to the method of the invention does not require ozone. This means that ozone (most preferably as a gas) is preferably not intentionally added for regeneration.

[0051] The electric current is 0.1 A / dm 2 ~10 A / dm 2 and preferably 0.2 A / dm 2 ~7.5 A / dm 2, more preferably 0.3 A / dm 2 ~5 A / dm 2 , even more preferably 0.4 A / dm 2 ~2.5 A / dm 2 , most preferably 0.5 A / dm 2 ~1 A / dm 2 The method of the present invention is preferably a direct current (DC) preferably having a current density in the range of. 0.1 A / dm 2 ~2 A / dm 2 , more preferably 0.2 A / dm 2 ~1 A / dm 2 , most preferably 0.3 A / dm 2 ~0.8 A / dm 2 A current density in the range of is highly preferred. The current density is the anode current density.

[0052] Generally, during the implementation of the method of the present invention, the current is applied permanently; most preferably, the method of the present invention to which a pause is applied even during the first and second steps (C) is preferred.

[0053] Preferably the current, most preferably the permanently applied current, prevents the presence of manganese species having an oxidation number +II.

[0054] In the regeneration compartment, the regeneration is preferably carried out in the method of the present invention in a temperature range of 20 °C to 65 °C, preferably 25 °C to 60 °C, more preferably 30 °C to 55 °C, most preferably 35 °C to 50 °C, even most preferably 37 °C to 43 °C.

[0055] Typically, a cathode and an anode are required to apply the current. Generally, in the production compartment, the method of the present invention including at least one anode and at least one cathode is preferred.

[0056] Generally, it is preferred that the method of the present invention in which at least one anode and at least one cathode have a distance in the range of 0.5 mm to 100 mm, preferably 1 mm to 90 mm, more preferably 2 mm to 80 mm, still more preferably 3 mm to 70 mm, even more preferably 4 mm to 60 mm, and most preferably 5 mm to 50 mm.

[0057] It is more preferred that the method of the present invention in which the regeneration compartment (20) includes a stack of a plurality of anodes and at least one cathode.

[0058] It is even more preferred that the method of the present invention in which a stack of a plurality of anodes and at least one cathode have a distance in the range of 0.5 mm to 100 mm, preferably 1 mm to 90 mm, more preferably 2 mm to 80 mm, still more preferably 3 mm to 70 mm, even more preferably 4 mm to 60 mm, and most preferably 5 mm to 50 mm. The distance is most preferably in the range of 9 mm to 70 mm, preferably 10 mm to 60 mm, more preferably 11 mm to 50 mm, still more preferably 12 mm to 30 mm, and most preferably 13 mm to 20 mm. The said distance is defined as the shortest distance between at least one anode and at least one cathode.

[0059] It is preferred that the method of the present invention in which the regeneration compartment includes at least one permeable barrier, preferably an ion-selective permeable barrier, and most preferably an ion-selective permeable membrane.

[0060] It is preferred that the method of the present invention in which at least one permeable barrier is not inorganic. It is preferred that at least one permeable barrier does not basically contain, and preferably does not contain, ceramics. In some cases, it is preferred that the regeneration compartment does not include a permeable barrier.

[0061] The method of the present invention in which at least one permeable barrier is organic is more preferred. The method of the present invention in which at least one permeable barrier is organic, contains fluorine (preferably fluorinated), and most preferably is organic and perfluorinated is more preferred. Most preferably, at least one permeable barrier is a Nafion-type membrane, although at least one membrane is not particularly limited to this specific brand.

[0062] Such barriers typically result in an anolyte sub-compartment containing anolyte and a catholyte sub-compartment containing catholyte. Preferably, the anolyte contains a dispensing acidic etching composition for regeneration, and most preferably is such a composition.

[0063] The stack of a plurality of anodes preferably contains an anode layer, preferably 3 or more anode layers, more preferably 3 - 300 anode layers, even more preferably 4 - 200 anode layers, still even more preferably 6 - 100 anode layers, most preferably 8 - 60 anode layers, and even most preferably 9 - 30 anode layers. Such a stack containing anode layers surprisingly shows very effective electrolytic regeneration without overly harmful shielding. This also enables a very highly dense design of the regeneration compartment.

[0064] In the stack, the anode layers preferably have a distance from each other in the range of 0.5 mm to 20 mm, preferably 1 mm to 15 mm, more preferably 2 mm to 12 mm, even more preferably 3 mm to 10 mm, most preferably 4 mm to 9 mm. In some cases, a very preferred distance is in the range of 1 mm to 6 mm, preferably 1.5 mm to 4 mm.

[0065] The method of the present invention in which at least one anode, preferably a stack of a plurality of anodes, and most preferably the anode layer contains a sheet, mesh, woven net, and / or expanded metal (i.e., metal lath) is preferred.

[0066] At least one anode, preferably a stack of multiple anodes, most preferably, the anode layer has a surface coefficient of 1 or more, preferably 1.4 or more, even more preferably 1.7 or more, still even more preferably 2 or more, most preferably 2.1 or more, and even most preferably 2.2 or more. The method of the present invention is preferred. In the context of the present invention, the surface coefficient indicates a parameter that defines the total effective surface area per geometric area. For example, a plate with a geometry of 1 m 2 has a surface coefficient of 2 (ignoring the area of the tip for simplicity), resulting in a total effective surface area (including the front and back sides) of 2 m 2 . As a result, the surface coefficient has no dimension / unit. For example, when the plate has holes with specified numbers and specified dimensions, and the mesh has openings, a surface coefficient typically less than 2 or even exceeding 2 can be obtained. However, the surface coefficients of commercially available meshes today typically do not exceed 2.5. In the context of the present invention, the surface coefficient defined above most preferably applies to the individual anode layers in the stack.

[0067] At least one anode, preferably a stack of multiple anodes, is platinum, titanium, niobium, lead, gold, an alloy containing at least one of them, their oxides, and / or a combination thereof; preferably, the method of the present invention containing at least one of platinum, titanium, and gold is preferred.

[0068] In fact, not all anode materials are suitable for the purposes achieved using the method of the present invention. Since the etching composition is acidic and due to the strong oxidation characteristics of manganese species, the material for the anode must be carefully selected. The minimum requirement is that each material is electrochemically inert to the acidic etching composition. The method of the present invention, in which at least one anode and the stack of multiple anodes each contain a platinum-plated anode and / or a platinum anode, preferably a platinum-plated titanium anode, and / or a platinum-plated niobium anode, is highly preferred.

[0069] Generally, at least one cathode preferably comprises stainless steel, zirconium, titanium, platinum, niobium, lead, an alloy comprising at least one of them, their oxides, and / or combinations thereof. Stainless steel, platinum-plated titanium, niobium, and / or zirconium are highly preferred.

[0070] Preferably, at least one cathode and at least one anode (each a stack of multiple anodes) are vertically oriented, preferably vertically oriented and parallel to each other in the method of the present invention.

[0071] Preferably, at least one anode (each a stack of multiple anodes) provides a total effective anode surface area A1, and at least one cathode provides a total effective cathode surface area A2, provided that A1 is greater than A2. In the context of the present invention, "total effective surface area" refers to the area that can be involved in regeneration.

[0072] Preferably, in the method of the present invention, A1:A2 ranges from 5:1 to 100:1, preferably from 10:1 to 85:1, more preferably from 15:1 to 70:1, even more preferably from 20:1 to 60:1, and most preferably from 30:1 to 50:1. In some cases, it is preferred that A1:A2 ranges from 5:1 to 30:1, preferably from 6:1 to 25:1, and more preferably from 7:1 to 20:1.

[0073] Step (B): In step (B), the plastic substrate is provided in the etching compartment.

[0074] The substrate is a plastic substrate or is also known as a polymer resin substrate (similarly an organic polymer substrate). Most preferably, the plastic substrate is a thermoplastic resin substrate.

[0075] Generally, it is preferred that the plastic substrate be handled vertically in the method of the present invention. In step (B), the preparation step preferably includes vertically loading (e.g., lifting) the plastic substrate into the etching chamber in the method of the present invention. Preferably, the etched plastic substrate is vertically unloaded (e.g., lifted) from the etching chamber after step (C).

[0076] The method of the present invention is preferred in which the plastic substrate contains a butadiene moiety, preferably polybutadiene.

[0077] Also, the method of the present invention is preferred in which the plastic substrate contains a nitrile moiety.

[0078] Also, the method of the present invention is preferred in which the plastic substrate contains an acrylic moiety.

[0079] Also, the method of the present invention is preferred in which the plastic substrate contains a styrene moiety.

[0080] In step (B), the method of the present invention is more preferred in which the plastic substrate includes acrylonitrile butadiene styrene (ABS), acrylonitrile butadiene styrene - polycarbonate (ABS-PC), polypropylene (PP), polyamide (PA), polyetherimide (PEI), polyether ketone (PEK), epoxy resin, a mixture or composite thereof.

[0081] The method of the present invention is preferred in which the polyether ketone (PEK) includes polyaryl ether ketone (PAEK), polyether ether ketone (PEEK), polyether ether ether ketone (PEEEK), polyether ether ketone ketone (PEEKK), polyether ketone ether ketone ketone (PEKEKK), polyether ketone ketone (PEKK), and / or a mixture thereof, preferably polyether ether ketone (PEEK), polyaryl ether ketone (PAEK), and / or a mixture thereof.

[0082] In some cases, the method of the present invention involving a two-component (2K) plastic substrate, preferably containing polycarbonate (PC) as one component, is highly preferred. Preferred 2K plastic substrates include polycarbonate / acrylonitrile butadiene styrene-polycarbonate (PC / ABS-PC), and / or polycarbonate / acrylonitrile butadiene styrene (PC / ABS). The etching composition utilized in the method of the present invention selectively etches ABS and ABS-PC without etching the PC component.

[0083] The method of the present invention is preferred wherein the plastic substrate includes a plurality of plastic substrates, preferably a plurality of plastic substrates fixed to at least one rack. From the beginning of the processing for etching the plastic substrates described throughout this text to the subsequent metallization step, the use of a metallization rack is common in decorative chrome plating. In particular, for decorative automotive parts, sanitary articles, and packaging / storage materials, this is highly preferred.

[0084] Preferably, in the method of the present invention, the plastic substrate is for decorative articles. Most preferably, the plastic substrate is a decorative automotive precursor part, a decorative sanitary precursor article, or a decorative packaging / storage precursor material. In the context of the present invention, the term "pre" in combination with the plastic substrate means that the subsequent execution of the metallization step on the etched plastic substrate results in the final plastic substrate with the desired function.

[0085] Step (C): In step (C) of the method of the present invention, the plastic substrate (1) is contacted with an acidic etching composition in an etching compartment so as to obtain an etched plastic substrate. The acidic etching composition (a) water, and (b) contains one or more manganese species.

[0086] As mentioned, the acidic etching composition contains water and is preferably an aqueous acidic etching composition. Most preferably, water is the only solvent in the acidic etching composition. Preferably, water has a concentration in the range of 10.8 mol / L to 27.5 mol / L, preferably 12 mol / L to 26 mol / L, more preferably 13.1 mol / L to 24.5 mol / L, even more preferably 13.9 mol / L to 23.3 mol / L, and most preferably 14.7 mol / L to 22.6 mol / L.

[0087] Also as mentioned, the etching composition is acidic. The acidic etching composition is strongly acidic and preferably has a pH of 2 or less, more preferably 1 or less, even more preferably 0.5 or less, and most preferably 0 or less in the method of the present invention.

[0088] All of the one or more manganese species preferably have a total concentration in the range of 0.005 mol / L to 0.3 mol / L, preferably 0.01 mol / L to 0.25 mol / L, more preferably 0.015 mol / L to 0.2 mol / L, even more preferably 0.02 mol / L to 0.15 mol / L, still even more preferably 0.025 mol / L to 0.11 mol / L, and most preferably 0.03 mol / L to 0.09 mol / L with respect to the total volume of the acidic etching composition in the method of the present invention.

[0089] In the acidic etching composition, the one or more manganese species contain permanganate ions. Preferably, the acidic etching composition is an acidic permanganate-based etching composition in the method of the present invention. This preferably means that in the acidic etching composition, permanganate ions are the active etching species, most preferably the active etching species, and even most preferably the most active etching species. In the acidic etching composition, 5 mol.% to 35 mol.%, preferably 8 mol.% to 30 mol.%, more preferably 10 mol.% to 27 mol.%, and most preferably 12 mol.% to 21 mol.% of all the manganese species are permanganate ions in the more preferred method of the present invention.

[0090] The permanganate ion has a concentration in the range of 0.002 mol / L to 0.09 mol / L, preferably 0.003 mol / L to 0.075 mol / L, more preferably 0.004 mol / L to 0.06 mol / L, even more preferably 0.005 mol / L to 0.045 mol / L, still even more preferably 0.006 mol / L to 0.03 mol / L, and most preferably 0.007 mol / L to 0.016 mol / L, based on the total volume of the acidic etching composition in the method of the present invention. This mainly refers to the concentration before contact.

[0091] Preferably, in the method of the present invention, the acidic etching composition (c) further contains one or more, preferably one, mineral acid.

[0092] One or more mineral acids include sulfuric acid and / or phosphoric acid, more preferably phosphoric acid, and most preferably phosphoric acid is the only mineral acid in the acidic etching composition, and even most preferably, phosphoric acid is the only acid in the acidic etching composition in the method of the present invention. Alternatively, this means that in some cases, the acidic etching composition preferably contains substantially no sulfuric acid and preferably contains no sulfuric acid in the method of the present invention.

[0093] The method of the present invention is preferred in which one or more mineral acids have a total concentration in the range of 7 mol / L to 12 mol / L, preferably 8 mol / L to 11 mol / L, based on the total volume of the acidic etching composition.

[0094] In the acidic etching composition, the method of the present invention is even more preferred in which phosphoric acid has a concentration in the range of 7.4 mol / L to 11.8 mol / L, preferably 7.8 mol / L to 11.5 mol / L, more preferably 8.2 mol / L to 11.2 mol / L, even more preferably 8.5 mol / L to 11 mol / L, most preferably 8.7 mol / L to 10.8 mol / L, and even most preferably 9.2 mol / L to 10.5 mol / L, based on the total volume of the acidic etching composition.

[0095] Preferably, in the method of the present invention, the acidic etching composition (d) further contains one or more ions selected from the group consisting of silver, bismuth, cerium, and lead.

[0096] (d) The ions defined by are typically utilized for electrolytic regeneration.

[0097] Preferably, the silver ions contain silver(I) and / or silver(II) ions, most preferably at least silver(I) ions.

[0098] Preferably, the bismuth ions contain bismuth(III) and / or (IV) ions.

[0099] Preferably, the lead ions contain lead(II) ions.

[0100] Most preferably, the one or more ions selected from (d) contain silver ions, preferably silver(I) and / or silver(II) ions, most preferably at least silver(I) ions.

[0101] The method of the present invention in which the ions defined by (d) have a total concentration in the range of 0.0001 mol / L to 0.2 mol / L, preferably 0.0005 mol / L to 0.15 mol / L, most preferably 0.001 mol / L to 0.1 mol / L with respect to the total volume of the acidic etching composition is preferred.

[0102] The method of the present invention in which the silver ions have a total concentration in the range of 0.0001 mol / L to 0.2 mol / L, preferably 0.0003 mol / L to 0.15 mol / L, most preferably 0.0005 mol / L to 0.1 mol / L with respect to the total volume of the acidic etching composition is more preferred. This is most preferably the case when the silver ions are the only ions according to (d).

[0103] Furthermore, in the etching composition, the silver(I) ions preferably have a concentration in the range of 0.0001 mol / L to 0.09 mol / L, more preferably 0.0002 mol / L to 0.07 mol / L, still more preferably 0.0005 mol / L to 0.05 mol / L, even more preferably 0.0007 mol / L to 0.03 mol / L, most preferably 0.001 mol / L to 0.01 mol / L, and even most preferably 0.0015 mol / L to 0.005 mol / L, according to the method of the present invention. When the silver ions are the only ions according to (d), most preferably, this applies.

[0104] In some cases, the acidic etching composition preferably contains alkali ions, most preferably sodium ions, in a total amount in the range of 0.002 mol / L to 0.5 mol / L, preferably 0.004 mol / L to 0.3 mol / L, based on the total volume of the acidic etching composition, according to the method of the present invention.

[0105] (a), (b), (c) and (d) preferably form 90% by mass or more, more preferably 92% by mass or more, still more preferably 94% by mass or more, even more preferably 96% by mass or more, most preferably 98% by mass or more, and even most preferably 99% by mass or more of the total mass of the acidic etching composition, according to the method of the present invention.

[0106] In step (C), the etching composition has a density in the range of 1.15 g / cm 3 to 1.51 g / cm 3 , preferably 1.22 g / cm 3 to 1.41 g / cm 3 , more preferably 1.24 g / cm 3 to 1.39 g / cm 3 , most preferably 1.26 g / cm 3 to 1.38 g / cm 3 , according to the method of the present invention. This also typically means that the acidic etching composition has a relatively low vapor pressure.

[0107] The acidic etching composition preferably does not substantially contain, preferably does not contain, methanesulfonic acid and its salts, preferably does not substantially contain, preferably does not contain C1 - C4 alkylsulfonic acids and their salts, and most preferably does not substantially contain, preferably does not contain C1 - C4 sulfonic acids and their salts, and the method of the present invention is preferred.

[0108] The acidic etching composition preferably does not substantially contain, preferably does not contain, bromide and iodide anions, preferably does not substantially contain, preferably does not contain chloride, bromide and iodide anions, and most preferably does not substantially contain, preferably does not contain halide anions, and the method of the present invention is preferred.

[0109] The acidic etching composition preferably does not substantially contain, preferably does not contain, trivalent chromium ions and hexavalent chromium compounds, preferably does not substantially contain, preferably does not contain any compounds and ions containing chromium, and the method of the present invention is preferred.

[0110] The acidic etching composition preferably does not substantially contain, preferably does not contain, palladium and / or copper ions, more preferably does not substantially contain, preferably does not contain palladium and / or copper compounds, and most preferably does not substantially contain, preferably does not contain any activator for subsequent metallization, and the method of the present invention is preferred. In other words, preferably, the acidic etching composition is not simultaneously an activation composition. Activation is most preferably carried out in subsequent individual steps using palladium.

[0111] The method of the present invention is preferred in which the acidic etching composition does not substantially contain, preferably does not contain, manganese(II) ions.

[0112] Although not wishing to be bound by theory, in a highly preferred permanganate - based acidic etching composition, it is considered that in addition to permanganate ions, manganese species having an oxidation number of (III) and / or (IV) are present.

[0113] In the method of the present invention, the contact in step (C) is a contact without immersion, i.e., a non-immersion dispensing of the acidic etching composition onto the plastic substrate (see also the above text for further information). This dispensing also represents, similarly or alternatively, the distribution of the liquid (in the sense of spreading) over the plastic substrate without immersion, dipping, and flooding. This means that the acidic etching composition is most preferably positively dispensed, spread, and distributed over the plastic substrate using pressure, respectively.

[0114] The non-immersion dispensing includes spraying, rinsing, and / or flushing, preferably spraying, rinsing, and / or flushing (most preferably, or referring to these), and the method of the present invention that is most preferably spraying is preferred.

[0115] In the context of the present invention, spraying results in a spray of the acidic etching composition for contacting the plastic substrate in step (C). This preferably (further or alternatively) includes spray mist, aerosol, and nebular dispersions. The spray preferably includes (at least partially) very fine spray droplets (e.g., with a diameter of about 100 nm) to medium and larger droplets (e.g., 10 μm, 100 μm, 500 μm, 1000 μm). This also includes sprays having droplets with a very homogeneous droplet size, as well as sprays having droplets with a very diverse droplet size. However, almost homogeneous sprays and sprays including droplets from fine to medium sizes are very preferred, respectively.

[0116] In the context of the present invention, rinsing results in a jet of the acidic etching composition. This preferably includes ejection, purge, and injection of the acidic etching composition, preferably directed directly at the plastic substrate. Typically, this type of dispensing is very directional when delivering the acidic etching composition onto the plastic substrate.

[0117] In the context of the present invention, rinsing includes screen rinsing (including laminar flow, waterfall rinsing, etc.), dripping, dropping, and showering of the acidic etching composition onto the plastic substrate. This is preferably performed without applying additional pressure.

[0118] Generally, the contact in step (C) is 50 L / m 2 / min to 250 L / m 2 / min, preferably 75 L / m 2 / min to 225 L / m 2 / min, more preferably 100 L / m 2 / min to 200 L / m 2 / min, most preferably 125 L / m 2 / min to 175 L / m 2 / min of the acidic etching composition is preferred. In the context of the present invention, this parameter is also named specific volume flow rate.

[0119] In step (C), the method of the present invention in which the plastic substrate and one or more dispensing nozzles have a distance in the range of 5 cm to 30 cm, preferably 8 cm to 26 cm, more preferably 10 cm to 22 cm is preferred.

[0120] In step (C), the non-immersion dispensing is preferably performed using a dispensing pressure in the method of the present invention. The dispensing pressure represents how strongly the acidic etching composition is dispensed (i.e., pressed) onto the plastic substrate. The pressure is most preferably combined with spraying.

[0121] In step (C), the non-immersion dispensing is more preferably performed using a dispensing pressure in the range of 0.3 bar to 5 bar, more preferably 0.5 bar to 4 bar, even more preferably 0.7 bar to 3 bar, and most preferably 1 bar to 2 bar in the method of the present invention.

[0122] Among the various types of dispensing described above, spraying requires less acidic etching composition than rinsing and flushing, and at the same time provides very good wetting. Therefore, spraying and spraying are most preferred respectively.

[0123] In step (C), non-dipping dispensing includes spraying using a spraying pressure in the range of 0.3 bar to 5 bar, more preferably 0.5 bar to 4 bar, even more preferably 0.7 bar to 3 bar, and most preferably 1 bar to 2 bar. Most preferred is the method of the present invention which is preferably such spraying.

[0124] Typically, the temperature of the acidic etching composition has a significant impact on the etching result, especially over time.

[0125] During contact in step (C), the acidic etching composition preferably has a temperature of 25°C or higher, preferably 28°C or higher, more preferably 30°C or higher, even more preferably 33°C or higher, most preferably 35°C or higher, and even most preferably 39°C or higher. This is also commonly called the etching temperature. Typically, the higher the temperature, the stronger the etching effect. However, if the temperature is too high, harmful decomposition is observed. In this regard, harmful means that the decomposition is too fast and strong, so that proper regeneration can no longer be carried out. Therefore, the temperature most preferably does not exceed 60°C.

[0126] Therefore, during contact in step (C), the acidic etching composition preferably has a temperature in the range of 25°C to 60°C, preferably 28°C to 55°C, more preferably 30°C to 50°C, even more preferably 33°C to 47°C, most preferably 35°C to 44°C, and even most preferably 39°C to 42°C.

[0127] As already indicated above, temperature control is made possible by the method of the present invention. This is most preferably aimed at providing a relatively high temperature during contact, but in contrast during regeneration, the temperature is lower in order to prevent or reduce unwanted decomposition. Thus, in some cases, in the etching compartment (10), the method of the present invention is preferred in which the acidic etching composition during contact has a higher temperature than the dispensed acidic etching composition treated in the regeneration compartment (30).

[0128] In the etching compartment (10), the method of the present invention is more preferred in which the acidic etching composition during contact has a temperature of 39 °C or higher, while the dispensed acidic etching composition treated in the regeneration compartment (30) has a temperature of less than 39 °C.

[0129] Most preferably, temperature control respectively includes and utilizes a heat exchanger.

[0130] However, in other cases, the method of the present invention is preferred in which the temperatures of the acidic etching composition and the dispensed acidic etching composition are substantially the same. This means that the temperature is maintained near the desired temperature with only very small temperature fluctuations, and most preferably a temperature of 40 °C ± 1 °C is maintained. In such cases, most preferably, no further energy and equipment for cooling are required.

[0131] The duration of contact with the acidic etching composition is usually referred to as the etching time. The contact in step (C) is preferably carried out for a time in the range of 1 minute to 120 minutes, more preferably 2 minutes to 90 minutes, still more preferably 3 minutes to 70 minutes, even more preferably 4 minutes to 50 minutes, and most preferably 5 minutes to 30 minutes. In some cases, 5 minutes to 15 minutes is very preferred.

[0132] In process (C), the method of the present invention in which manganese dioxide (MnO2) is not substantially deposited, preferably not deposited, on the etched plastic substrate is preferred. Thus, in the method of the present invention, in order to reduce the manganese dioxide on the etched plastic substrate, i.e., to dissolve MnO2 by chemical reduction with a reducing agent, a process is not required (and thus not applied). Thus, preferably, the etched plastic substrate obtained after process (C) is not contacted with each composition containing a reducing agent. A typical rinse with water is sufficient. Thus, the method of the present invention further including a rinse with water after process (C), more preferably a rinse with water not containing a reducing agent capable of chemically reducing manganese dioxide, is preferred.

[0133] Furthermore, in process (C) of the method of the present invention, the dispensed acidic etching composition results from this process. In the context of the present invention, this mainly includes the majority of the acidic etching composition that is ultimately utilized for etching, and in this portion, one or more manganese species mainly have a lower oxidation number than before contact. This means that they are in a more reduced state after contact mainly not only by etching but also by decomposition. However, the dispensed acidic etching composition may further include a portion of the acidic etching composition that has not yet contacted the plastic substrate or has simply missed the plastic substrate (and thus is no longer in contact with the plastic substrate). This portion is typically less than the portion included in the etching. In fact, compared to the acidic etching composition, one or more manganese species in the dispensed acidic etching composition have a lower oxidation number on average. As a result, at least a portion of the dispensed acidic etching composition is treated in a regeneration compartment for regeneration by applying an electric current. Preferably, all of the dispensed acidic etching composition is treated in the regeneration compartment.

[0134] The portion of the dispensing acidic etching composition is preferably transferred to a regeneration compartment assisted by a transfer pipeline (e.g., an inlet side regeneration pipeline, refer to FIG. 1), most preferably by a pump, in the method of the present invention. In the regeneration compartment, the acidic etching compositions are respectively formed and reformed. The portion processed in the regeneration compartment preferably does not exist in the etching compartment at least temporarily. Therefore, preferably, etching and regeneration are respectively performed at separate positions and by separate devices.

[0135] After regeneration, the processed portion is returned to the acidic etching composition. Therefore, the method of the present invention includes a cyclic flow. The processed and returned portions of the dispensing acidic etching composition preferably represent the replenishment and supplementation of the acidic etching composition for further step (c) within the method of the present invention, respectively.

[0136] The method of the present invention is preferably performed repeatedly. This means that the method of the present invention includes steps (C) such as the first, second, third, etc. This similarly preferably applies to step (B), and preferably therefore each step (C) includes a new (in the sense of additional) plastic substrate. Therefore, the method of the present invention is preferably performed in a loop. This similarly most preferably repeatedly, most preferably continuously, includes that the portion is processed in the regeneration compartment and returned to the acidic etching composition.

[0137] Further steps: After step (C), that is, after etching the plastic substrate, typically metallization follows.

[0138] After step (C), (D) contacting the etched plastic substrate with an activation composition so as to obtain an activated plastic substrate; and / or (preferably and) (E) A method according to the present invention is preferred which further comprises contacting an etched plastic substrate or an activated plastic substrate (preferably an activated plastic substrate) with a first metallization composition such that a first metal or alloy layer is deposited thereon to provide a first metallized plastic substrate.

[0139] In this regard, the method of the present invention is respectively preferably also a method of activating a plastic substrate and a method of metallizing a plastic substrate.

[0140] In the method of the present invention, preferably, step (D) is a separate step and is independent of step (C). In other words, the acidic etching composition used in step (C) is preferably not the activation composition used in step (D).

[0141] In step (D) of the method of the present invention, the etched plastic substrate is contacted with the activation composition.

[0142] In step (D), the activation composition contains palladium, preferably dissolved palladium ions or colloidal palladium, most preferably colloidal palladium. Preferably, the method of the present invention is such that the colloidal palladium contains tin.

[0143] In step (D), the activation composition contains palladium at a total concentration in the range of 20 mg / L to 200 mg / L, preferably 40 mg / L to 150 mg / L, even more preferably 50 mg / L to 110 mg / L, most preferably 55 mg / L to 80 mg / L, based on the total volume of the activation composition. Preferably, this total concentration includes both dissolved palladium ions and colloidal palladium. The above concentrations are based on the palladium element.

[0144] In step (D), the activation composition preferably has a temperature in the range of 25°C to 70°C, preferably 30°C to 60°C, even more preferably 36°C to 50°C, most preferably 39°C to 46°C.

[0145] In step (D), the contact is preferably carried out for a time in the range of 1 minute to 15 minutes, more preferably 2 minutes to 12 minutes, even more preferably 3 minutes to 9 minutes, and most preferably 4 minutes to 7 minutes, according to the method of the present invention.

[0146] Step (D) (D-1) comprises the step of contacting the activated plastic substrate with an accelerator composition to modify the activated plastic substrate, and the accelerator composition - In step (D), when the activation composition contains colloidal palladium, instead of a reducing agent, tin ions, at least one complexing agent for tin ions, or - In step (D), when the activation composition contains palladium ions but does not contain colloidal palladium, the method of the present invention preferably contains a reducing agent for reducing palladium ions to metallic palladium.

[0147] In step (D-1), the accelerator composition preferably contains tin ions, at least one complexing agent for tin ions, and is acidic, and more preferably further contains sulfuric acid, instead of a reducing agent, according to the method of the present invention.

[0148] In the context of the present invention, step (D-1) as defined above is carried out after contacting the etched plastic substrate with the activation composition so as to obtain an activated plastic substrate.

[0149] Typically, after step (D-1), a sufficiently activated plastic substrate is obtained.

[0150] In step (E) of the method of the present invention, the sufficiently etched plastic substrate or the activated plastic substrate is contacted with a first metallization composition such that a first metal or alloy layer is deposited thereon, resulting in a first metallized plastic substrate.

[0151] Thus, step (E) either follows the activation of step (D) or is applied to an etched plastic substrate as a direct metallization that does not require activation. In the latter case, step (D) is not necessary. However, the method of the present invention in which steps (D) and (E) are carried out is preferred.

[0152] In step (E), the first metallization composition preferably comprises nickel ions, preferably nickel ions and a reducing agent for reducing said nickel ions, such that the first metal or alloy layer becomes a nickel or nickel alloy layer respectively. Thus, the first metallized plastic substrate is preferably a first nickel or nickel alloy metallized plastic substrate.

[0153] In step (E), the first metallization composition is alkaline and preferably has a pH in the range of 8.0 - 11.0, preferably 8.2 - 10.2, more preferably 8.4 - 9.3, and most preferably 8.6 - 9.0. However, in some rare cases, in step (E), the first metallization composition is alternatively acidic, preferably weakly acidic, and most preferably has a pH in the range of 6 - 6.9.

[0154] In step (E), the first metallization composition preferably has a temperature in the range of 18°C - 60°C, preferably 20°C - 55°C, even more preferably 23°C - 50°C, and most preferably 26°C - 45°C.

[0155] Preferably, the first metallized plastic substrate is subsequently further metallized.

[0156] After step (D) or (E), (F) The method of the present invention preferably further comprises contacting the activated plastic substrate or the first metallized plastic substrate with a second metallization composition such that a second metal or alloy layer is deposited thereon to provide a second metallized plastic substrate.

[0157] If process (F) follows process (D), process (E) is preferably omitted and the second metallization composition basically corresponds to the first metallization composition. However, this is not very preferable. More preferably, processes (E) and (F) are carried out continuously. This does not exclude the rinsing process.

[0158] Process (F) preferably allows for at least two alternative methods.

[0159] In the first alternative method, in process (F), the second metallization composition preferably contains copper ions in the range of 0.002 mol / L to 0.4 mol / L, more preferably in the range of 0.004 mol / L to 0.25 mol / L, still more preferably in the range of 0.005 mol / L to 0.1 mol / L, and most preferably in the range of 0.007 mol / L to 0.04 mol / L, based on the total volume of the second metallization composition. Most preferably, the copper ions are copper (II) ions.

[0160] In the first alternative method, the second metallization composition is acidic and preferably has a pH of 1 or less, more preferably 2 or less. In some cases, the second metallization composition is alkaline and a method containing copper ions is alternatively preferred.

[0161] In some cases, the second metallization composition contains pyrophosphate and is most preferably a method that contains pyrophosphate and is alkaline.

[0162] In the first alternative method, the second metallization composition preferably contains at least one acid (most preferably acidic as defined above, preferably at least one inorganic acid, more preferably at least sulfuric acid). Preferably, at least one acid (more preferably at least one inorganic acid, most preferably at least sulfuric acid) has a total concentration in the range of 0.001 mol / L to 0.5 mol / L, preferably in the range of 0.003 mol / L to 0.3 mol / L, more preferably in the range of 0.005 mol / L to 0.1 mol / L, and most preferably in the range of 0.007 mol / L to 0.07 mol / L, based on the total volume of the second metallization composition. The method of the present invention is more preferred.

[0163] In the first alternative method, the second metallization composition preferably has a temperature in the range of 20°C to 80°C, preferably in the range of 21°C to 60°C, more preferably in the range of 22°C to 45°C, even more preferably in the range of 23°C to 40°C, and most preferably in the range of 24°C to 35°C. The method of the present invention is more preferred.

[0164] In the first alternative method, the second metallization composition preferably does not substantially contain, and preferably does not contain, a reducing agent for copper ions. The method of the present invention is more preferred.

[0165] In the first alternative method, the second metallization composition is preferably an immersion copper composition. Thus, copper ions are not reduced to metallic copper by a reducing agent. This is also known as displacement plating.

[0166] In the second alternative method, in step (F), the second metallization composition preferably contains nickel ions.

[0167] In the second alternative method, the second metallization composition preferably does not substantially contain, and preferably does not contain, a reducing agent for nickel ions. The method of the present invention is more preferred.

[0168] In the second alternative method, the second metallization composition is acidic and preferably has a pH in the range of 1.0 to 5.0, preferably 2.0 to 4.5, more preferably 2.8 to 4.0, and most preferably 3.3 to 3.7. The method of the present invention is more preferred.

[0169] In the second alternative method, the second metallization composition preferably has a temperature in the range of 25°C to 70°C, preferably 35°C to 65°C, even more preferably 45°C to 61°C, and most preferably 52°C to 58°C. The method of the present invention is more preferred.

[0170] In the second alternative method, the contacting is preferably carried out for a time in the range of 1 minute to 10 minutes, preferably 2 minutes to 8 minutes, and most preferably 2.5 minutes to 5.5 minutes. The method of the present invention is more preferred.

[0171] In the second alternative method, the current is preferably in the range of 0.3 A / dm 2 ~10.0 A / dm 2 , preferably in the range of 0.5 A / dm 2 ~8.0 A / dm 2 , more preferably in the range of 0.8 A / dm 2 ~6.0 A / dm 2 , even more preferably in the range of 1.0 A / dm 2 ~4.0 A / dm 2 , most preferably in the range of 1.3 A / dm 2 ~2.5 A / dm 2 and is applied in the range. Thus, the second alternative method is preferably electrolytic nickel deposition.

[0172] In the second alternative method, the second metallization composition preferably contains chloride ions and / or (preferably and) boric acid. The method of the present invention is more preferred.

[0173] In the second alternative method, the second metallization composition is most preferably a Watts nickel composition. Thus, in the second alternative method, the second metallization composition preferably contains chloride ions, sulfate ions, and boric acid. The method of the present invention is preferred.

[0174] After step (F), the second metallized plastic substrate is preferably further metallized.

[0175] After step (F), The method of the present invention preferably further comprises the step of contacting the second metallized plastic substrate with a third metallization composition such that a third metal or alloy layer is deposited thereon by electrolysis to provide a third metallized plastic substrate.

[0176] The method of the present invention is preferably such that the third metallization composition contains copper ions in a concentration in the range of 0.05 mol / L to 3 mol / L, more preferably in the range of 0.1 mol / L to 2 mol / L, still more preferably in the range of 0.2 mol / L to 1.5 mol / L, and most preferably in the range of 0.3 mol / L to 1 mol / L, based on the total volume of the third metallization composition.

[0177] In step (G), the method of the present invention is preferably such that a current, preferably a direct current, is applied.

[0178] The method of the present invention is more preferably such that the third metallization composition is acidic or alkaline. In this context, the acidic third metallization composition represents a first alternative method, and the alkaline third metallization composition represents a second alternative method, and the first alternative method is more preferred.

[0179] The method of the present invention is more preferably such that the third metallization composition according to the first alternative method has a pH of 2 or less, preferably 1 or less.

[0180] The third metallization composition according to the first alternative method is more preferably the method of the present invention comprising at least one acid, preferably at least one inorganic acid, most preferably at least sulfuric acid. Preferably, at least one acid (more preferably at least one inorganic acid, most preferably at least sulfuric acid) has a total concentration in the range of 0.1 mol / L to 5 mol / L, preferably in the range of 0.2 mol / L to 3 mol / L, more preferably in the range of 0.3 mol / L to 2 mol / L, and most preferably in the range of 0.4 mol / L to 1.5 mol / L with respect to the total volume of the second metallization composition.

[0181] The third metallization composition according to the first alternative method is more preferably the method of the present invention containing chloride ions, preferably chloride ions with a total concentration of 500 mg / L or less, preferably 300 mg / L or less, and most preferably 150 mg / L or less.

[0182] The third metallization composition according to the first alternative method is more preferably the method of the present invention having a temperature in the range of 20°C to 49°C, preferably in the range of 22°C to 43°C, more preferably in the range of 24°C to 39°C, and most preferably in the range of 26°C to 35°C.

[0183] The third metallization composition according to the second alternative method is more preferably the method of the present invention having a pH in the range of 7.1 to 12, preferably in the range of 7.4 to 11, and most preferably in the range of 7.6 to 10.

[0184] The third metallization composition according to the second alternative method is more preferably the method of the present invention containing cyanide ions or pyrophosphate ions, preferably pyrophosphate ions.

[0185] The third metallization composition according to the second alternative method is more preferably the method of the present invention having a temperature in the range of 50°C to 70°C.

[0186] In the context of the present invention, the terms first, second, and third metallized plastic substrates indicate the correspondence with each process defined above in the text, rather than the quantity / number of metallized plastic substrates.

[0187] After the step (G), the third metallized plastic substrate is preferably contacted with one or more further metallization compositions each containing trivalent chromium ions such that a metal layer of chromium or a chromium alloy is deposited thereon.

[0188] Most preferably, the metal layer of chromium or chromium alloy is respectively the outermost metal layer. Thus, most preferably, the method of the present invention is for metallizing a plastic substrate, and the metallization includes chromium deposition, preferably decorative chromium deposition.

[0189] In the context of the present invention, preferably, a series of steps, in particular a series of metallization steps, are defined. Preferably, this does not exclude intermediate steps between steps, such as rinsing steps. Thus, preferably, in the method of the present invention, an intermediate step, most preferably a rinsing step, is carried out between at least one of steps (B) and (C) and preferably steps (D) to (G).

[0190] The present invention is further illustrated by reference to the following figures and examples.

[0191] In the reservoir (20), an acidic etching composition used in the method of the present invention is prepared. The acidic etching composition is a permanganate-based acidic etching composition containing 9 mol / L to 11 mol / L of phosphoric acid.

[0192] Via the supply line (14), the acidic etching composition is transferred from the reservoir (20) into the etching compartment (10) assisted by the pump (17).

[0193] In the etching compartment (10), the dispensing line (13) distributes the acidic etching composition to a plurality of dispensing nozzles (12), preferably spray nozzles. In Figure 1, the dispensing line (13) is shown twice. For reasons of simplicity only, it is not shown that the second dispensing line (13) is also connected to the supply line (14).

[0194] A rack (2) containing a plurality of plastic substrates (1) is disposed between two dispensing pipelines (13), each containing a plurality of dispensing nozzles (12). The rack (2) having a plurality of plastic substrates (1) each is vertically loaded into the etching chamber (10) through an opening (11) equipped with a door. After the rack (2) is suitably arranged, the door is closed and the etching chamber (10) is closed, but not completely airtight.

[0195] To etch the plurality of plastic substrates (1) of the rack (2), the etching process is initiated by dispensing, preferably spraying, an acidic etching composition onto the plurality of plastic substrates (1) using a dispensing pressure and a spraying pressure in the range of 1 to 2 bar respectively. As a result, uniform etching is obtained across all the plastic substrates (1).

[0196] During etching, the acidic etching composition is distributed across the plurality of plastic substrates (1) of the rack (2), resulting in a dispensed acidic etching composition. The dispensed acidic etching composition is collected in a reservoir (20). In some cases, the reservoir (20) is spatially separated from the etching chamber (10) but is fluidly connected via a pipe or a transfer pipeline.

[0197] To avoid escape and external contamination of the acidic etching composition from the etching chamber (10) during step (C), a gentle flow of air, preferably a laminar flow, is applied to form a vertical gas flow (3) from the top to the bottom. The vertical gas flow (3) is applied at least when the door of the opening (11) is opened. The ventilation duct (15) absorbs the vertical gas flow (3) and, together with it, mainly the mist of the dispensed acidic etching composition. In the liquid separator (16), the gas (i.e., air here) is separated from any liquid, and the liquid is replenished to the reservoir (20) via a transfer pipeline.

[0198] In FIG. 1, the acidic etching composition in the reservoir (20) has substantially the same temperature as the dispensed acidic etching composition through the plurality of dispensing nozzles (12). Therefore, a heating unit (not shown) applies heat to the reservoir (20), thereby maintaining a relatively constant temperature throughout the process. However, in some cases, the dispensed acidic etching composition is allowed to cool and is regenerated in the regeneration compartment (30) at a lower temperature. In such cases, the acidic etching composition reaches a certain temperature by the heating unit shortly before contact with the plastic substrate.

[0199] Regarding regeneration, the dispensed acidic etching composition is processed in the regeneration compartment (30) and transferred through the inlet-side regeneration pipeline (21). In the regeneration section (30), an electric current is preferably applied continuously. Since permanganate ions are the active etching species, permanganate ions are continuously formed (i.e., re-oxidized) at least intermittently and most preferably continuously in the regeneration compartment (30). The regenerated, i.e., re-oxidized, dispensed acidic etching composition is returned to the reservoir (20) via the outlet-side regeneration pipeline (22).

Example

[0200] The present invention is here illustrated by reference to the following non-limiting examples.

[0201] (Example (A)) Spraying + electrolytic regeneration according to the present invention In step (A), the etching compartment was prepared in the form of a box (dimensions 1.4 m × 0.9 m × 0.7 m) made of polyvinylidene fluoride (PVDF). The box has an upper opening that can be opened and closed by a door. The total spraying window area was about 100 dm 2 It was.

[0202] In the etching compartment, 112 spray nozzles (40 on each longitudinal side and 16 on each short side (i.e., transverse direction)) were distributed over 14 dispensing pipelines as dispensing nozzles, and the total spraying window area dm 2It corresponded to an injection nozzle of about 1.1 minutes per shot. In later tests conducted on a larger scale, it was shown that the horizontal nozzles could be omitted without any negative impact on the etching. Each spray nozzle was manufactured from polyvinylidene fluoride (PVDF).

[0203] During etching, the etching compartment was not airtight. A vertical air flow of ambient air from the top to the bottom was applied to prevent and escape dangerous spray mist. The vertical air flow had a flow rate of about 500 m 3 / h while the etching compartment was open to raise and lower a rack containing a plurality of plastic substrates. Two ventilation ducts were installed near the bottom of the etching compartment to suck out the vertical air flow. A liquid separator was used to separate the ambient air from the spray mist.

[0204] A separate reservoir fluidly connected to the etching compartment by a pipeline formed a reservoir. In this example, an acidic etching composition with a total volume of 200 L, which was significantly smaller compared to the ordinary immersion / dip method, was utilized (placed in the reservoir). The reservoir was heated so that the acidic etching composition reached a temperature of about 40 °C to 41 °C, and then it was actively pumped through the supply pipeline and the dispensing pipeline to a plurality of plastic substrates in the etching compartment.

[0205] The regeneration compartment 30 for the regeneration of the dispensed acidic etching composition included six subunits, each of which included a stack of a single cathode and nine anode layers (each anode layer was expanded metal, had a distance of 1 - 5 mm from the adjacent one, and had a surface factor of about 2). The cathode was made of stainless steel, and each anode layer was manufactured from platinum-plated niobium. The anodic current technically applicable to each subunit was in the range of 40 - 300 A, and a relatively low current was actually applied and required; see Table 1 below. The current was applied permanently. The distance between the cathode and the stack of anode layers was about 5 - 30 mm. Each stack of anode layers had a total effective anode surface area A1 of about 300 dm 2 and the total effective cathode surface area A2 was about 30 dm 2and provided an A1:A2 ratio of about 10. The Nafion-type membrane separated the stacking of the cathode and anode layers, resulting in an anode solution (a regenerated dispensed acidic etching composition) and a cathode solution containing phosphoric acid. The stacking of the positive electrode and the anode layer had a vertical orientation.

[0206] In step (B) of the method of the present invention, a plurality of round or rod-shaped plastic substrates (ABS and ABS-PC, each having a surface dimension in the range of 0.1 dm 2 to 10 dm 2 ) were used. The plastic substrates were mounted on a rack. The rack was vertically lifted into the etching compartment and arranged as such.

[0207] Before contacting the plastic substrates with the acidic etching composition, they were pretreated for 10 minutes by contacting them with a cleaning solution (Uniclean 151, a product of Atotech) and subsequently rinsed. Non-swelling or swelling compositions were used as required. Accordingly, there was no contact with an organic solvent. As a result, cleaned plastic substrates were obtained.

[0208] After washing, the cleaned plastic substrates were contacted with an aqueous surfactant solution for 1 minute to improve wettability. Rinsing was not applied between this step and the subsequent step (C). It should be said that the use of a surfactant is not always necessary.

[0209] In step (C), a permanganate-based etching composition containing about 10 mol / L of phosphoric acid, about 10 mmol / L of permanganate ions (a total manganese species concentration of about 60 mmol / L), and about 1 to 2 mmol / L of silver (I) ions was used.

[0210] In step (C), a spray was formed using a spray pressure of 2 bar, and the acidic etching composition was sprayed onto the plastic substrate. Etching was carried out for a length of time of 8 minutes for the ABS plastic substrate and 15 minutes for the ABS-PC plastic substrate using a temperature of approximately 40°C. During etching, the dispensed acidic etching composition was collected in a reservoir, partially transferred from there to a regeneration compartment, and subsequently returned to the reservoir.

[0211] The etching quality was evaluated and summarized in Table 1 below.

[0212] After step (C), rinsing was carried out using water.

[0213] In step (D), the etched plastic substrate was contacted with an activation composition containing colloidal palladium (approx.: 50 mg / L of Pd, temperature 40°C, contact time 5 minutes) to obtain an activated plastic substrate.

[0214] In subsequent step (D-1), the activated plastic substrate was contacted with an accelerator composition containing a complexing agent for tin ions but not a reducing agent at 45°C for 3 minutes. As a result, a sufficiently activated plastic substrate was obtained.

[0215] Before step (E), rinsing was carried out using water.

[0216] In step (E), in order to obtain a first metallized plastic substrate, the sufficiently activated and rinsed plastic substrate was contacted with a first metallization composition. For electroless nickel plating, the sufficiently activated plastic substrate was contacted with an alkaline (pH, approximately 8.6 - 9.0) first metallization composition (having a temperature of approximately 40°C; contact time approximately 10 minutes). To obtain a nickel alloy metallized plastic substrate, the first metallization composition contained approximately 3.5 g / L of nickel ions and approximately 15 g / L of hypophosphite ions as a reducing agent for nickel ions.

[0217] In step (F), a nickel alloy metallized plastic substrate was contacted with a second acidic metallization composition containing copper(II) ions (immersion copper - i.e., copper displacement plating; pH < 1; temperature approximately 25°C, without a reducing agent) for approximately 0.5 minutes.

[0218] Thereafter, the second metallized plastic substrate containing the second metal layer (i.e., copper) was rinsed with water.

[0219] In step (G), after rinsing, to obtain a third metallized plastic substrate having a copper layer with a layer thickness exceeding 30 μm, each plastic substrate was contacted with a third metallization composition (acidic pH) (contact time approximately 70 minutes, 25°C, 40 g / L copper ions; electrolytic copper plating using approximately 4 A / dm 2 ).

[0220] Subsequently, a further metallization step was performed to finally deposit a chromium layer. The metallized plastic substrate having a copper layer with a layer thickness exceeding 30 μm was subjected to nickel plating at least once or multiple times.

[0221] In the final metallization step, to obtain a metallized plastic substrate having a chromium layer, each plastic substrate was contacted with a further metallization composition (acidic pH, 25°C - 60°C) containing 15 g / L - 30 g / L trivalent chromium and boric acid.

[0222] Finally, the coverage and optical defects, especially bubbles, were analyzed to evaluate the optical quality of the chromium layer. As a result, no haze and other optical defects, especially bubbles or other physical defects, were observed. In particular, the chromium layer showed a very homogeneous optical distribution. This result was also obtained in all further examples (see below), but for Examples (A) and (B), it was observed that fewer plating defects were obtained. Non-immersion dispensing was observed to avoid gas bubbles from adhering to plastic substrates having particularly delicate surface geometries (e.g., surface grooves, channels, inner edges, etc.). Such geometries often result in etching defects and, as a result, plating defects.

[0223] Furthermore, the plastic substrate with the final chromium layer also passed the PV1200 thermal cycle test (including a maximum of +80°C and -40°C over 96 hours and 8 cycles).

[0224] For the adhesion test, each plastic substrate obtained after step (G) (i.e., plated using copper) was subjected to a common test. The adhesion values for ABS and ABS-PC are summarized in Table 1 below.

[0225] Compared to the following examples, only Example (A) shows a combination of fewer plating defects as a plastic substrate with a sophisticated surface geometry and significantly reduced energy and chemical consumption.

[0226] (Example (B)) Spray + supply and bleed; comparative example Example (B) was carried out in the same manner as Example (A), but with the following modifications.

[0227] No regeneration compartment was prepared, and thus, electrolytic regeneration was not applied. Instead, at intervals, a specific portion of the dispensed acidic etching composition was removed at a certain removal rate and replenished equally with freshly prepared acidic etching composition to maintain the concentration of permanganate ions. The removal rate was approximately 1.5% by volume per hour with respect to the total volume of the acidic etching composition.

[0228] In this approach, current was not required, but a significant and never desired amount of waste acidic etching composition was obtained over time instead, which is a major environmental and economic disadvantage. As in Example (A), Example (B) was maintained at a total volume of 200 L to prepare a sufficient amount of acidic etching composition for spraying. However, during step (C) of Example (B), 3 L / hour was removed and replenished in the same manner to maintain the amounts and etching quality as reported above for Example (A).

[0229] In Example (B), the acidic etching composition did not contain silver ions.

[0230] (Example (C)) Immersion + supply and bleed; Comparative example Similar to Example (B), but Example (C) including the following changes was carried out.

[0231] In step (C), ordinary immersion / liquid immersion / dip was carried out instead of non-immersion dispensing. Each etching bath had a total volume of 525 L, which was more than twice the total volume used in Examples (A) and (B).

[0232] Example (C) represents the worst assembly case from an environmental and economic perspective and contains a much larger amount of waste liquid etching composition. To maintain 525 L, a removal rate of about 1.5% by volume was applied as in Example (B), resulting in a removal and replenishment of about 8 L / hour.

[0233] (Example (D)) Immersion + electrolytic regeneration; Comparative example Similar to Example (A), but Example (D) including the following changes was carried out.

[0234] Also here, ordinary immersion / liquid immersion / dip was carried out in step (C) instead of non-immersion dispensing. As used in Example (C), each etching bath also had a total volume of 525 L. However, electrolytic regeneration required a significantly larger current per subunit compared to Example (A) (see Table 1 below).

[0235] This comparative example clearly shows the great advantage of combining non-immersion dispensing and electrolytic regeneration as described above in Example (A).

[0236]

Table 1

[0237] Table 1 generally shows that ABS and ABS-PC plastic substrates can be etched efficiently and successfully in all basically different examples. In other words, the method of the present invention does not impair the good results already obtained in ordinary applications. Generally, a slight difference in adhesion of about 0.1 N / mm is not important.

[0238] In the above Examples (A) to (D), only Example (A) significantly avoids the generation of waste liquid amount, and at the same time clearly shows the minimum energy and chemical consumption. The simple etching results are very similar, but Example (A) provides the best economic and ecological results and is excellently suitable for replacing the ordinary immersion / dip method.

[0239] Furthermore, surprisingly, it was observed that fewer gas bubbles adhered to the plastic substrates in Examples (A) and (B) for non-immersion dispensing. This results in fewer etching defects and, as a result, fewer plating defects. Such gas bubble defects are typical of the immersion etching process.

[0240] In addition to this, it was found that the process before wetting the surface of the plastic substrate can be removed in Examples (A) and (B) without a negative effect on the etching quality.

[0241] In summary, Example (A) is the only example that combines fewer gas bubble defects with the most reduced energy and chemical consumption without degrading the etching quality.

Claims

1. A method for etching a plastic substrate (1), comprising: (A) providing an etching chamber (10) and a regeneration chamber (30); (B) providing the plastic substrate (1) in the etching chamber (10); (C) contacting the plastic substrate (1) in the etching chamber (10) with an acidic etching composition containing (a) water, and (b) one or more manganese species such that an etched plastic substrate is obtained; wherein - the contacting in step (C) is non-immersion dispensing of the acidic etching composition onto the plastic substrate (1), resulting in a dispensed acidic etching composition, and - at least a portion of the dispensed acidic etching composition is treated in a regeneration chamber (30) for regeneration by application of an electric current and returned to the acidic etching composition.

2. The method according to claim 1, wherein the etching chamber (10) includes one or more dispensing nozzles (12) for the non-immersion dispensing in step (C), preferably a plurality of dispensing nozzles, most preferably a plurality of spray nozzles.

3. The method according to claim 1 or 2, wherein in the etching chamber (10), the one or more dispensing nozzles (12) at least partially comprise or consist entirely of fluoropolymer plastic, titanium, stainless steel, combinations thereof and / or composites.

4. The method according to any one of claims 1 to 3, wherein in the etching chamber (10), a vertical gas flow (3) is preferably applied from the top to the bottom to transport at least a portion of the dispensed acidic etching composition.

5. The method according to claim 4, wherein the etching chamber includes a ventilation duct (15) for sucking out the vertical gas flow, which is connected to a liquid separator (16) for separating liquid from the gas flow.

6. The method according to any one of claims 1 to 5, wherein the regeneration chamber (20) includes a stack of a plurality of anodes and at least one cathode.

7. The method according to any one of claims 1 to 6, wherein the stack of a plurality of anodes and at least one cathode has a distance in the range of 0.5 mm to 100 mm, preferably 1 mm to 90 mm, more preferably 2 mm to 80 mm, still more preferably 3 mm to 70 mm, yet still more preferably 4 mm to 60 mm, and most preferably 5 mm to 50 mm.

8. The method according to any one of claims 1 to 7, wherein in the acidic etching composition, the one or more manganese species contain permanganate ions, and preferably, the acidic etching composition is an acidic permanganate-based etching composition.

9. The method according to claim 8, wherein the permanganate ions have a concentration in the range of 0.002 mol / L to 0.09 mol / L, preferably 0.003 mol / L to 0.075 mol / L, more preferably 0.004 mol / L to 0.06 mol / L, still more preferably 0.005 mol / L to 0.045 mol / L, yet still more preferably 0.006 mol / L to 0.03 mol / L, most preferably 0.007 mol / L to 0.016 mol / L, based on the total volume of the acidic etching composition.

10. The method according to any one of claims 1 to 9, wherein the non-dip dispensing includes spraying, flushing and / or rinsing, preferably is spraying, flushing and / or rinsing, and most preferably is spraying.

11. The contact in step (C) is 50 L / m 2 / min to 250 L / m 2 / min, preferably 75 L / m 2 / min to 225 L / m 2 / min, more preferably 100 L / m 2 / min to 200 L / m 2 / min, most preferably 125 L / m 2 / min to 175 L / m 2 The method according to any one of claims 1 to 10, comprising dispensing an acidic etching composition in an amount in the range of / min.

12. The method according to any one of claims 1 to 11, wherein in step (C), the non-dip dispensing is carried out using a dispensing pressure.

13. The method according to any one of claims 1 to 12, wherein in step (C), the non-dip dispensing includes spraying using a spraying pressure in the range of 0.3 bar to 5 bar, more preferably 0.5 bar to 4 bar, still more preferably 0.7 bar to 3 bar, most preferably 1 bar to 2 bar, and preferably is such spraying.

14. The method according to any one of claims 1 to 13, wherein during the contact in step (C), the acidic etching composition has a temperature of 25 °C or higher, preferably 28 °C or higher, more preferably 30 °C or higher, still more preferably 33 °C or higher, most preferably 35 °C or higher, and even most preferably 39 °C or higher.

15. The method according to any one of claims 1 to 14, wherein in the etching compartment (10), the acidic etching composition during the contact has a higher temperature than the dispensed acidic etching composition treated in the regeneration compartment (30).

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