Metal-plastic hybrid materials having aluminum and / or its alloys as the metal component

Abstract

The present invention relates to a method for preparing a metal-plastic hybrid material, said material comprising at least one substrate having at least one metal surface made at least in part from aluminum and / or its alloys, and at least one thermoplastic material applied onto said metal surface of the substrate, in particular by using an acidic aqueous composition. Furthermore, the present invention also relates to a metal-plastic hybrid material obtainable by this method, to a method for using the acidic aqueous composition for bonding a substrate to a plastic, to such a metal-plastic hybrid material, and to a method for using the metal-plastic hybrid material as a component in the automotive, construction or electronics industry.

Description

[Technical Field]

[0001] The present invention relates to a method for preparing a metal-plastic hybrid material, said material comprising at least one substrate having at least one metal surface made at least in part from aluminum and / or its alloys, and at least one thermoplastic material applied onto said metal surface of the substrate, in particular by using an acidic aqueous composition. Furthermore, the present invention also relates to a metal-plastic hybrid material obtainable by this method, to a method for using the acidic aqueous composition for bonding a substrate to a plastic, to such a metal-plastic hybrid material, and to a method for using the metal-plastic hybrid material as a component in the automotive, construction or electronics industry. [Background technology]

[0002] Metal-plastic hybrid materials are one of the solutions proposed for reducing weight in components such as structural parts used in the automotive industry, or other parts such as battery covers, powertrain elements, control panels, etc. To obtain such parts and components, plastic and metal can be joined in several ways, and researchers are developing bonding materials that ideally combine the properties of both materials. However, joining dissimilar materials such as metal and plastic is extremely difficult due to the different chemical properties of the two materials and the resulting dissimilarities, such as the shrinkage of plastics observed during molding, as with thermoplastic materials.

[0003] Traditionally, adhesives have been used to bond metals and thermoplastic materials. However, manufacturing such products using adhesives not only requires additional manufacturing steps, but also leads to a decrease in adhesive strength over time or a loss of bonding strength at high temperatures. Therefore, applying such methods to technical fields such as the automotive industry is not appropriate, regardless of the associated economic and ecological disadvantages, because considerable heat resistance is often required here for electrodeposition and painting processes.

[0004] Aluminum is now often the metal component material of choice for constructing metal-plastic hybrid materials, especially in electric vehicle applications or electronics applications such as smartphones, mobile devices, etc. Various methods have been reported for joining aluminum to thermoplastic materials, especially in the electronics industry, and the aluminum surface is typically anodized, treated with plasma, or etched in a controlled manner to induce surface roughness, for example using nano-molding technology (NMT), before injection molding.

[0005] Generally, plastic-metal hybrid materials are often formed by injection molding a thermoplastic material onto the surface of a metal part, such as an aluminum part, to form nanometer-sized pores, micrometer-sized pores, or both. For example, WO 2020 / 003208 A1 discloses such a plastic-metal hybrid material, in which the plastic contains a polyketone. The pores are typically formed by the aforementioned controlled chemical etching or anodization process. The bonding mechanism is based on mechanical interlocking, in which a molten plastic material is directly injected into the pores on the metal surface.

[0006] Controlled chemical etching and anodizing processes (also known as flash anodizing) both require specialized equipment and have the disadvantage of requiring an extra step of etching or anodizing to generate surface roughness when preparing plastic-metal hybrid materials. Such controlled chemical etching and anodizing processes are disclosed, for example, in EP 2 894 240 A1 and EP 3 854 909 A1, and JP 2021-186993 A. EP 2 894 240 A1 relates to a metal-resin composite structure obtained by bonding a metal component and a resin component formed from a thermoplastic resin composition. To achieve sufficient adhesion between the metal component and the resin, the surface of the metal component is necessarily roughened. EP 3 854 909 A1 relates to a metal / resin composite structure including a metal component and a resin component integrated with the metal component and formed from a resin composition containing a thermoplastic resin. The metal member has a fine uneven structure on the surface at least at the portion where it is integrated with the resin member, i.e., the surface roughness is the result of a surface roughening process. Furthermore, an inorganic particle layer is always present between the metal and the resin member. JP 2021-186993 A discloses a metal / resin composite material including a metal member and a cured resin bonded to the metal member. The metal member has a fine uneven structure on the surface of the joint portion with the cured resin prepared from a thermosetting polyurethane elastic material, and therefore has roughness.

[0007] However, the lifespan of roughened, especially etched or anodized, surfaces of metal materials, such as aluminum-based materials, is very limited. Taking anodizing as an example, the application window or processing of plastic materials is only a few hours; otherwise, the pores close spontaneously and adhesion is not achieved. Furthermore, the aforementioned nano-molding technology (NMT) can only be applied to very well-defined nanopores and very small components, limiting its application to very small electronic devices. For example, polybutylene terephthalate and polyethylene terephthalate (PBT and PET) have poor acid resistance, resulting in discoloration during component processing. Nylon-based materials, such as polyamide (PA) and polyphthalamide (PPA), also have poor acid resistance.

[0008] It is therefore necessary to provide a metal-plastic hybrid material and a method for preparing the same, which material contains aluminum and / or its alloys as the metal component and which has excellent permanent or at least long-term adhesive properties as far as the adhesion between metal and plastic is concerned, but which at the same time can be prepared without the need to use conventional adhesives and, more particularly, without the need to carry out a separate surface roughening step such as a surface anodizing step or chemical etching, which material further allows the use of a wider range of thermoplastic polymer materials, including PBT and PET, than conventional processes for preparing metal-plastic hybrid materials containing aluminum and / or its alloys, and which can be prepared in a flexible, easy, ecologically and economically advantageous manner. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] WO 2020 / 003208 A1 [Patent Document 2] EP 2 894 240 A1 [Patent Document 3] EP 3 854 909 A1 [Patent Document 4] JP 2021-186993 A Summary of the Invention [Problem to be solved by the invention]

[0010] The object underlying the present invention is to provide a metal-plastic hybrid material and a method for its preparation, which material contains aluminum and / or its alloys as the metal component and which has excellent permanent or at least long-term adhesive properties as far as the adhesion between metal and plastic is concerned, but at the same time can be prepared without the need to use conventional adhesives and, in particular, without the need to carry out a separate surface roughening step such as a surface anodizing step or chemical etching; this material, moreover, allows the use of a wider range of thermoplastic polymer materials, including PBT and PET, than conventional processes for preparing metal-plastic hybrid materials containing aluminum and / or its alloys; and it can be prepared in a flexible, easy, ecologically and economically advantageous manner. [Means for solving the problem]

[0011] This object has been solved by the subject matter of the present claims and the preferred embodiments thereof disclosed herein, ie the subject matter described herein.

[0012] A first subject of the present invention is a method for preparing a metal-plastic hybrid material, said material comprising a substrate S1 having at least one metal surface and at least one thermoplastic material applied onto said metal surface of said substrate S1, said method comprising at least steps 1) and 2) and optionally step 3a) or 3b), namely 1) applying an aqueous acidic composition at least partially onto at least one metal surface of the substrate S1 to at least partially form a film on said surface, and optionally drying or curing said film to form a dried or cured layer, the metal surface is made at least in part of aluminum and / or at least one aluminum alloy, the acidic aqueous composition comprises, in addition to water, as at least one component a1), at least one water-soluble polymer having at least one functional group selected from acid groups, hydroxyl groups, amino groups and mixtures thereof, as at least one component a2), at least one metal cation selected from the group consisting of titanium ions, zirconium ions, hafnium ions and mixtures thereof, and preferably, as at least one component a3), free fluoride anions; 2) applying at least one thermoplastic polymer material TM1 at least partially onto the film or dried or cured layer obtained after step 1), said at least one thermoplastic polymer material TM1 is applied i) in the form of a foil or ii) by injection in the molten state onto the film or dried or cured layer obtained after step 1) to form a metal-plastic hybrid material; and 3a) optionally injecting at least one thermoplastic polymer material TM2, present in molten state and identical or different to the thermoplastic material TM1 applied in step 2), at least partially onto the surface of the foil of metal-plastic hybrid material obtained after steps 2) and i), or 3b) optionally applying a further substrate S2 having at least one metal surface onto the surface of the foil of metal-plastic hybrid material obtained after steps 2) and i), said surface being made at least partly from aluminum and / or at least one aluminum alloy and having been subjected to the treatment of step 1) of the method, or vice versa, Includes:

[0013] A further subject of the invention is a metal-plastic hybrid material obtainable by this method.

[0014] A further subject of the present invention is the use of an acidic aqueous composition as defined in connection with step 1) of the method of the invention for adhering a metal surface of a substrate, at least partly made of aluminum and / or at least one of its alloys, to a thermoplastic material present on said surface in the form of a foil or applied thereto by injection molding, such as a thermoplastic polymer material TM1.

[0015] A further subject of the present invention is such a metal-plastic hybrid material, namely a metal-plastic hybrid material comprising: a substrate S1 having at least one metallic surface made at least in part from at least one aluminum and / or at least one alloy thereof; a film or dry layer or hardened layer applied at least partially onto said metal surface, said film or dry layer or hardened layer being obtainable from at least partially applying onto said metal surface an aqueous acidic composition as defined in relation to said step 1) of the method of the present invention; at least one thermoplastic polymer material TM1 in the form of a foil or in the form obtained by injection molding, which is applied at least partially onto the film or the dried layer or the cured layer, preferably as defined in optional step 2) of the method of the invention, and Optionally, furthermore, at least one thermoplastic polymer material TM2, identical or different to the thermoplastic polymer material TM1, and at least partly applied on the at least one thermoplastic polymer material TM1 in a form obtainable from injection molding, with the proviso that the thermoplastic polymer material TM1 is applied in the form of a foil, or Optionally, the substrate S2 further comprises at least one metal surface, said surface being at least partially made of aluminum and / or at least one aluminum alloy, said substrate having a film or dry layer or hardened layer at least partially applied to said metal surface, said film or dry layer or hardened layer being obtainable by applying an aqueous acidic composition as defined in relation to step 1) of the method of the present invention, said film or dry layer or hardened layer at least partially present on said metal surface of the substrate S2 being located adjacent to at least one thermoplastic polymer material TM1, with the proviso that the thermoplastic polymer material TM1 is applied in the form of a foil.

[0016] Preferably, when the metal-plastic hybrid material comprises a further substrate S2, it can be considered as a sandwich structure comprising two substrates S1 and S2, each of which is attached to one surface of the thermoplastic material TM1 present in the form of a foil by means of an attached film or a dried or hardened layer that can be obtained from the application of an aqueous acidic composition as defined in relation to the above step 1) of the method of the present invention. Preferably, the substrates S1 and S2 are each a sheet or coil made of aluminum and / or its alloys.

[0017] A further subject of the invention is the use of said metal-plastic hybrid material or of a metal-plastic hybrid material obtainable by the method of the invention as a component in the automotive, construction or electronics industry.

[0018] It has been found that the acidic aqueous composition used in the present invention can provide a conversion coating on the metal surface of a substrate, while at the same time providing good adhesion between the metal surface and the thermoplastic material TM1 applied thereon due to the adhesion-promoting properties of the resulting conversion coating or layer. It has been found that sufficient adhesion would not be achieved without the application of the acidic aqueous composition. Furthermore, and particularly surprisingly, it has been found that the water-soluble polymer present in the acidic aqueous composition functions as an adhesion promoter in this regard. Achieving good adhesion is particularly important, since the strength of the adhesive bond between the metal surface and the thermoplastic material used has been found to significantly affect the lifespan of the metal-plastic hybrid material. Furthermore, it has been found that surfaces comprising metallic aluminum and / or its alloys can be used with substrates of all kinds of different shapes, particularly substrates in sheets, coils, and / or other shapes.

[0019] Furthermore, it has been found that applying the acidic aqueous composition used in accordance with the invention to a metal surface according to step 1) constitutes a surface treatment of said metal surface, and that in particular the presence of at least one metal cation selected from the group consisting of titanium ions, zirconium ions, hafnium ions and mixtures thereof, preferably in combination with molybdenum cations, not only provides a microstructuring of the surface by pickling passivation, which is important for mechanical interlocking with the thermoplastic polymer material TM1, but also provides a true chemical bond via the functional groups of the water-soluble polymer used. Since the surface roughness is already induced by applying the acidic aqueous composition used in accordance with the invention to the metal surface according to step 1), there is no need to apply conventional surface treatments such as plasma treatment, chemical etching and / or anodizing to the metal surface, let alone in a separate method step.

[0020] Furthermore, it has been particularly surprising to discover that the adhesion problems and challenges known in the prior art when combining two dissimilar materials, i.e., a thermoplastic polymer such as TM1 on the one hand and aluminum and / or its alloys on the other, can be overcome by the inventive method for preparing a metal-plastic hybrid material, in particular by using an acidic aqueous composition for chemical pretreatment of the metal surface as exemplified in step 1) of the inventive method prior to carrying out step 2). In particular, it has been discovered that the method for preparing a metal-plastic hybrid material allows the use of thermoplastic polymers such as TM1, which have relatively high melting temperatures, such as polyamides, especially polyamide 6, and can also be applied directly by injection molding according to step 2) of the inventive method. Furthermore, it also allows the use of thermoplastic polyesters such as PET and PBT, despite their low acid resistance. Direct injection molding of a thermoplastic material onto a metal surface according to step 2) offers many advantages, among them simplicity, robustness, and a wide range of applications. The flexibility of this method is achieved, for example, by the fact that step 1) of the method can be used in a coil line with a roll coater or by spraying with a job coater, making this method extremely flexible.

[0021] It has also been found that by applying the acidic aqueous composition used in the present invention, not only is excellent adhesion achieved but also very good corrosion prevention effects are obtained.

[0022] Even more surprisingly, it has been found that the method of the present invention allows the thermoplastic polymer TM1 to be thermoplastically injected directly onto an aluminium-containing metal surface according to step 2), despite the very short contact times between TM1 and the metal surface, and despite the significant temperature difference between the molten thermoplastic polymer material TM2, which may exceed 200° C., and the substrate temperature of the surface, which is usually room temperature, i.e., in the range of 18° C. to 25° C., but which may also be heated, if necessary, up to, for example, 80° C. In particular, it has been found that the presence of functional groups of the water-soluble polymer in the acidic aqueous composition used allows very rapid bonding, before the thermoplastic material has had time to cool once applied / injected.

[0023] Furthermore, it has been found that the use of an acidic aqueous composition for chemical pretreatment of a metal surface as exemplified in step 1) of the method of the present invention, prior to carrying out step 2), also provides strong adhesion to the thermoplastic material TM1 when applied as a foil compound to the treated metal surface. It has also been found that the foil formed by applying TM1 can then further function as an adhesive or interface layer onto which a further thermoplastic material TM2, identical or different from TM1, can be applied by injection in optional step 3a) of the method, particularly when carried out if the foil from TM1 formed in step 2) is chemically compatible with the material TM2 applied in optional step 3a). Likewise, the product obtained after step 2), in particular when TM1 has been applied as a foil to the metal surface, can also be applied in an optional step 3b) to the metal surface of a further substrate, if the metal surface of said further substrate has also been subjected to a chemical pretreatment by using the acidic aqueous composition used in the present invention, as defined in step 1) of the method of the present invention, to form a sandwich structure, said surface also being made at least partly from aluminium and / or its alloys, in which the foil produced using TM1 is sandwiched between two metal surfaces of two substrates. DETAILED DESCRIPTION OF THE INVENTION

[0024] In the sense of the present invention, the term "comprises", for example in connection with an acidic aqueous composition, preferably has the meaning of "consists of". For example, with respect to an acidic aqueous composition, in addition to all essential components present therein, it is also possible for one or more of the further optional components specified below to be included therein. All components may in each case be present in their preferred embodiments as specified below.

[0025] The percentages and amounts by weight (wt%) of any of the components shown below present in the acidic aqueous composition are in each case based on the total weight of the acidic aqueous composition and add up to 100 wt%.

[0026] Methods of the Invention A first subject of the present invention is a method for preparing a metal-plastic hybrid material, said material comprising a substrate S1 having at least one metal surface and at least one thermoplastic material applied onto said metal surface of said substrate S1, said method comprising at least steps 1) and 2) and optionally step 3a) or 3b).

[0027] The method may comprise further steps besides steps 1) and 2) and optionally 3a) or 3b), for example a cleaning step of the metal surface may be carried out before step 1), for example with an acidic, alkaline or pH-neutral, preferably alkaline, cleaning composition, wherein in the case of an acidic cleaning composition said composition is different from the acidic aqueous composition used in step 1).

[0028] More specifically, prior to step 1), any one or more of the following steps may be performed in this order: Step A-1): A step of cleaning the surface of the substrate, preferably alkaline or acidic, and optionally rinsing it thereafter; Step B-1): A step of acid-pickling, i.e., etching, the surface of the substrate, and then rinsing the surface of the substrate; Step C-1): contacting the surface of the substrate with an aqueous composition comprising at least one mineral acid, or alternatively with an aqueous alkaline composition or a pH-neutral aqueous composition, said aqueous composition being different from the acidic aqueous composition used in step 1); and Step D-1): A step of rinsing the surface of the article obtained after contact in steps C-1) and / or B-1).

[0029] Alternatively, steps A-1) and B-1) may be carried out in one step, which is preferred. Preferably, both steps A-1) and B-1) are carried out.

[0030] The optional step C-1) serves to remove aluminum oxide, unwanted alloy components, skin, brushing dust, etc. from the substrate surface, thereby activating the surface for subsequent treatment in step C-1). This step corresponds to a chemical etching step. Preferably, the at least one mineral acid in the composition in step C-1) is sulfuric acid and / or nitric acid and / or phosphoric acid, more preferably sulfuric acid. The content of the at least one mineral acid is preferably in the range of 1.5 to 75 g / L, more preferably 2 to 60 g / L, and most preferably 3 to 55 g / L. The composition used in step C-1) preferably further contains one or more metal ions selected from the group consisting of titanium ions, zirconium ions, hafnium ions, and mixtures thereof, and optionally further contains molybdenum ions. In treating the part, the treatment time with the composition in step C-1) is preferably in the range of 30 seconds to 10 minutes, more preferably 40 seconds to 6 minutes, and most preferably 45 seconds to 4 minutes. The treatment temperature is preferably in the range of 20 to 55°C, more preferably 25 to 50°C, and most preferably 30 to 45°C. In the treatment of the coil, the treatment time is preferably in the range of 3 seconds to 1 minute, and most preferably 5 to 20 seconds. However, preferably, the optional step C-1) is not carried out.

[0031] Preferably, the method does not include a step of surface treatment of the metal surface S1, in particular prior to carrying out step 1), selected from plasma treatment, chemical etching and / or anodization. Neither optional step B-1) nor C-1) represents a chemical etching step capable of generating any surface roughness of the substrate, as disclosed in the prior art. Optional steps B-1) and / or C-1) are rather merely preparatory steps for the subsequent deposition of the film resulting from the application of the aqueous acidic composition in step 1).

[0032] The rinsing step D-1) and any rinsing that is part of step A-1) are preferably carried out using deionized water or tap water. Preferably, step D-1) is carried out using deionized water.

[0033] Preferably, the method does not include a step involving treatment with chromium ions, such as Cr(VI) ions and / or Cr(III) ions. Base material The metal surface of the substrate S1 is at least partially made of aluminum and / or at least one aluminum alloy. Preferably, the entire metal surface is at least partially made of aluminum and / or at least one aluminum alloy. More preferably, such a substrate S1 is a metal substrate made at least partially of aluminum and / or at least one aluminum alloy. Preferably, the metal surface does not contain steel and / or steel alloys in an amount exceeding the amount of aluminum and / or its alloys present therein. Examples of aluminum alloys are aluminum-magnesium alloys, aluminum-magnesium-silicon alloys, aluminum-copper alloys, aluminum-zinc alloys, and aluminum-zinc-copper alloys.

[0034] In the case of aluminum alloys, the alloy preferably contains more than 50% by weight of aluminum, based on the total weight of the alloy. This method is particularly suitable for all aluminum alloys containing more than 50% by weight of aluminum, in particular aluminum magnesium alloys including, but not limited to, AA5005, and aluminum magnesium silicon alloys including, but not limited to, AA6014, AA6060, and AA6063, cast alloys such as AlSi7Mg, AlSi9Mg, AlSi10Mg, AlSi11Mg, AlSi12Mg, and AlSiMg for wrought alloys. Aluminum magnesium alloys including AA5005 and aluminum magnesium silicon alloys including AA6060 and AA6063 are commonly used, for example, in the field of aluminum finishing and / or for the treatment of wheels and / or other automotive parts such as electric vehicle components, e.g., battery housings. This method is also suitable for all alloys of the so-called AA1000, AA2000, AA3000, AA4000, AA5000, AA6000, AA7000 and AA8000 series. A preferred example of the AA2000 series is AA2024. A preferred example of the AA7000 series is AA7075. AA2024 and AA7075 are often used in the aerospace industry. Further examples are Galvalume® and Galfan®.

[0035] All kinds of substrates of different shapes and geometries can be used, preferably the substrates are selected from sheets and coils, parts, in particular parts suitable for use in the automotive industry, and mixtures thereof.

[0036] Method step 1) In step 1), the aqueous acidic composition is applied at least partially onto at least one metal surface of the substrate S1 to at least partially form a film on said surface. Drying or curing of the optional film may be carried out in step 1) to form a dried or cured layer. Such drying or curing is preferably carried out. Drying is preferably carried out at a temperature in the range of, for example, 15°C to 100°C, more preferably in the range of 18°C ​​to 95°C, and especially in the range of 20°C to 90°C.

[0037] Step 1) is preferably a contacting step in which the metal surface is contacted with an aqueous acidic composition. "Contacting" includes spraying, dip coating, cascade or roll coating procedures. "Contacting" may also be submerging the surface in water or manually wiping or brushing.

[0038] The treatment time, i.e. the period during which the surface is in contact with the acidic aqueous composition used in step 1), is preferably in the range of 15 seconds to 20 minutes, more preferably 30 seconds to 10 minutes, most preferably 45 seconds to 5 minutes, for example 1 minute to 3 minutes, in each case when parts, in particular parts suitable for use in the automotive industry, are used as substrates. If the substrate is a coil, the treatment time is preferably less than 1 minute, more preferably less than 30 seconds or less than 15 seconds, even more preferably less than 10 seconds, and even more preferably in the range of 1 second to 5 seconds.

[0039] The temperature of the acidic aqueous composition used in step 1) is preferably 5 to 50°C, more preferably 15 to 45°C, and most preferably 25 to 40°C.

[0040] By carrying out step 1), a conversion coating is preferably formed on the metal surface. Preferably, after drying or curing, preferably after drying, the presence of component a2) in the acidic aqueous composition results in a conversion coating of 0.1 to 50 mg / m, in each case calculated as metal, determined by XRF (X-ray fluorescence spectroscopy). 2 , more preferably 0.2 to 30 mg / m 2 , and even more preferably 0.5 to 20 mg / m2 , and even more preferably 1.0 to 15 mg / m 2 , and even more preferably 1.5 to 10 mg / m 2 , especially 2.0 to 8 mg / m 2 A coating layer is formed having a coating mass of zirconium and / or titanium and / or hafnium, preferably zirconium and / or titanium, more preferably zirconium. Preferably, if optional component a4) defined below is also present, the coating layer has a coating mass of 0.1 to 40 mg / m, calculated as metal, determined by XRF (X-ray fluorescence spectroscopy). 2 , more preferably 0.2 to 30 mg / m 2 , and even more preferably 0.5 to 20 mg / m 2 , and even more preferably 1.0 to 15 mg / m 2 , and even more preferably 1.5 to 10 mg / m 2 , especially 2.0 to 8 mg / m 2 The coating mass has molybdenum of 1000 ppm.

[0041] acidic aqueous composition The acidic aqueous composition comprises, in addition to water, as at least one component a1), at least one water-soluble polymer having at least one functional group selected from acid groups, hydroxyl groups, amino groups, and mixtures thereof, and as at least one component a2), at least one metal cation selected from the group consisting of titanium ions, zirconium ions, hafnium ions, and mixtures thereof, all components present in the composition being different from one another.

[0042] Preferably, the acidic aqueous composition used in step 1) has a pH value in the range of 0.1 to <7.0, more preferably 0.5 to 6.5, even more preferably 1.0 to 6.0, even more preferably 1.5 to 5.5, even more preferably 2.0 to 5.0, even more preferably 2.5 to 4.5, even more preferably 3.0 to 4.0, even more preferably 1.7 to 3.5, and most preferably >3.0 to <3.7. Preferably, the pH value is measured at room temperature (23°C). The pH can be adjusted, if necessary, using nitric acid, aqueous ammonia, and / or sodium carbonate.

[0043] In the sense of the present invention, the term "aqueous" in relation to the acidic aqueous composition used in step 1) preferably means that the composition comprises at least 50% by weight, preferably at least 60% by weight, more preferably at least 70% by weight, particularly preferably at least 80% by weight, and most preferably at least 90% by weight of water, based on the total content of organic and inorganic solvents, including water. Thus, the composition may contain at least one organic solvent in addition to water, but in an amount less than the amount of water present.

[0044] Preferably, the acidic aqueous composition used in step 1) contains at least 50% by weight, preferably at least 60% by weight, more preferably at least 70% by weight, particularly preferably at least 80% by weight and most preferably at least 90% by weight of water, in each case based on its total weight.

[0045] The acidic aqueous composition can be used as a dip-coat bath. However, as outlined above in relation to step 1), it can also be applied by virtually any conventional coating procedure, such as spray coating, roll coating, brushing, wiping, etc. Spraying, dipping, cascade or roll coating are preferred.

[0046] The acidic aqueous composition used in step 1) is preferably a solution.

[0047] Preferably, the acidic aqueous composition used in step 1) has a temperature in the range of 18 to 35°C, more preferably 20 to 35°C, especially 20 to 30°C.

[0048] Water-soluble polymer (component a1) The acidic aqueous composition comprises as at least one component a1) at least one water-soluble polymer having at least one functional group selected from acid groups, hydroxyl groups, amino groups and mixtures thereof.

[0049] The solubility is determined at a temperature of 20° C. and atmospheric pressure (1.013 bar).

[0050] Preferably, the at least one water-soluble polymer used as component a1) is present in the acidic aqueous composition in an amount ranging from 0.05 to 2.0 g / L or 0.05 to 5.0 g / L, more preferably from 0.10 to 1.8 g / L, even more preferably from 0.12 to 1.6 g / L, even more preferably from 0.14 to 1.5 g / L, even more preferably from 0.16 to 1.4 g / L, even more preferably from 0.18 to 1.2 g / L, and most preferably from 0.20 to 1.0 g / L. Alternatively, the at least one water-soluble polymer used as component a1) is present in the acidic aqueous composition in an amount ranging from 0.1 to 15.0 g / L, more preferably from 0.3 to 12.0 g / L, even more preferably from 0.5 to 11.0 g / L, and even more preferably from 0.7 to 10.0 g / L.

[0051] Preferably, the at least one water-soluble polymer used as component a1) has at least one functional group selected from carboxylic acid groups, phosphonic acid groups, sulfonic acid groups, hydroxyl groups, amino groups, and mixtures thereof, more preferably selected from carboxylic acid groups, hydroxyl groups, amino groups, and mixtures thereof, even more preferably selected from carboxylic acid groups.

[0052] Preferably, the at least one water-soluble polymer used as component a1) is a homopolymer or copolymer obtainable from the polymerization of at least one ethylenically unsaturated monomer, at least some of which have at least one functional group selected from acid groups, hydroxyl groups, amino groups, and mixtures thereof, more preferably a homopolymer or copolymer obtainable from the polymerization of at least one vinyl and / or (meth)acrylic monomer, at least some of which have at least one functional group selected from acid groups, hydroxyl groups, amino groups, and mixtures thereof. In particular in the case of vinylphenol homopolymers and copolymers, these polymers can be modified by condensation reaction, in particular the Mannich reaction, with compounds having amino groups, such as ethanolamine and / or N-methylglucamine.

[0053] Examples of monomers containing acid groups include acrylic acid, methacrylic acid, and maleic acid. Examples of monomers containing hydroxyl groups include 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 3-hydroxypropyl acrylate, 3-hydroxypropyl methacrylate, 4-hydroxybutyl acrylate, 4-hydroxybutyl methacrylate, 3-phenoxy-2-hydroxypropyl (meth)acrylate, glycerol mono(meth)acrylate, N-(2-hydroxypropyl) (meth)acrylamide, allyl alcohol, hydroxystyrene, hydroxyalkyl vinyl ethers such as hydroxybutyl vinyl ether and vinylbenzyl alcohol, vinylphenol, and vinyl alcohol. Examples of additional non-functional monomers that can be used, particularly those that do not have acid groups, hydroxyl groups, or mixtures thereof, include ethylene, propylene, butylene, and aliphatic C1-C 30(Meth)acrylic acid esters of monoalcohols, such as methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, i-propyl (meth)acrylate, n-butyl (meth)acrylate, i-butyl (meth)acrylate, t-butyl (meth)acrylate, lauryl (meth)acrylate, 2-ethylhexyl (meth)acrylate, 3-propylheptyl (meth)acrylate, stearyl (meth)acrylate, behenyl (meth)acrylate, benzyl (meth)acrylate, cyclohexyl (meth)acrylate, and isobornyl (meth)acrylate, but particularly aliphatic C1-C 30 Non-functional vinyl monomers are preferred over non-functional (meth)acrylic esters of monoalcohols.

[0054] If polymer a1) is a homopolymer, it is preferably a poly(meth)acrylic acid. If polymer a1) is a copolymer and has at least acid groups as functional groups, it is preferably a (meth)acrylic copolymer, preferably comprising a polymer backbone and at least one side chain attached to said polymer backbone, and carrying acid groups, such as carboxylic acid groups.

[0055] The term "(meth)acrylic" means "acrylic" and / or "methacrylic". Similarly, "(meth)acrylate" means acrylate and / or methacrylate, and "(meth)acrylic" means acrylic and methacrylic. A "(meth)acrylic polymer" is formed at least in part from "acrylic monomers" and / or "methacrylic monomers", but may also contain non-acrylic and non-methacrylic monomer units if other ethylenically unsaturated monomers, such as vinyl monomers, are additionally used when polymer a1) is a copolymer. Preferably, the backbone of such a (meth)acrylic copolymer is formed from more than 50 mol %, even more preferably more than 75 mol % of (meth)acrylic monomers.

[0056] Preferably, the at least one water-soluble polymer used as component a1) is selected from: (meth)acrylic acid homopolymers, in particular acrylic acid homopolymers; copolymers of (meth)acrylic acid and at least one ethylenically unsaturated monomer other than (meth)acrylic acid, in particular copolymers of (meth)acrylic acid and maleic acid; Copolymers of maleic acid and at least one ethylenically unsaturated monomer other than maleic acid, in particular copolymers of maleic acid and ethylene and / or propylene and / or at least one alkyl vinyl ether, such as methyl vinyl ether; Copolymers of vinylphosphonic acid and at least one ethylenically unsaturated monomer other than vinylphosphonic acid, in particular copolymers of (meth)acrylic acid and vinylphosphonic acid, and copolymers of (meth)acrylic acid, vinylphosphonic acid and maleic acid; vinyl alcohol homopolymer, copolymers of vinyl alcohol and at least one ethylenically unsaturated monomer different from vinyl alcohol, such as vinyl acetate; vinylphenol homopolymer, a copolymer of vinylphenol and at least one ethylenically unsaturated monomer different from vinylphenol; a copolymer of vinyl mercaptoethanol and at least one ethylenically unsaturated monomer different from vinyl mercaptoethanol, and Homopolymers and copolymers of vinylphenols, and mixtures thereof, modified with at least one amine, preferably at least one primary amine, such as N-ethanolamine and / or N-methylglucamine, preferably via the Mannich base reaction based on the condensation of formaldehyde with a primary or secondary amine.

[0057] More preferably, the at least one water-soluble polymer used as component a1) is selected from (meth)acrylic acid homopolymers, in particular acrylic acid homopolymers, copolymers of (meth)acrylic acid and at least one ethylenically unsaturated monomer other than (meth)acrylic acid, in particular copolymers of (meth)acrylic acid and maleic acid, copolymers of maleic acid and at least one ethylenically unsaturated monomer other than maleic acid, in particular copolymers of maleic acid and at least one alkyl vinyl ether such as ethylene and / or propylene and / or methyl vinyl ether, vinyl alcohol homopolymers, copolymers of vinyl alcohol and at least one ethylenically unsaturated monomer other than vinyl alcohol, homopolymers and copolymers of vinylphenol modified with at least one amine, preferably at least one primary amine, such as N-ethanolamine and / or N-methylglucamine, and mixtures thereof. Particularly preferred polymers are N-methylglucamine-modified poly(vinylphenol), N-ethanolamine-modified poly(vinylphenol), poly(maleic acid-co-vinyl methyl ether), poly(maleic acid-co-acrylic acid), polyacrylic acid, poly(vinylphosphonic acid-co-acrylic acid), poly(acrylic acid-co-maleic acid-co-vinylphosphonic acid), poly(acrylic acid-co-vinylmercaptoethanol), poly(acrylic acid-co-maleic acid-co-vinylmercaptoethanol), and mixtures thereof.

[0058] Preferably, the at least one water-soluble polymer has a weight average molecular weight (M) in the range of 1000 to 350000 g / mol, preferably 2000 to 325000 g / mol, more preferably 3000 to 300000 g / mol, even more preferably 4000 to 375000 g / mol. W The weight average molecular weight is determined by the method described in the "Method" section below.

[0059] If a polymer a1) is used which is a poly(meth)acrylic acid, in particular a polyacrylic acid, it preferably has a weight average molecular weight (M) in the range of 10,000 to 350,000 g / mol, preferably 50,000 to 325,000 g / mol, more preferably 100,000 to 300,000 g / mol, even more preferably 150,000 or 200,000 to 375,000 g / mol. W If a polymer a1) is used which is a copolymer at least partially prepared from maleic acid, it preferably has a weight average molecular weight (M) in the range of 10,000 to 200,000 g / mol, preferably 15,000 to 150,000 g / mol, more preferably 20,000 to 100,000 g / mol, even more preferably 30,000 to 80,000 g / mol. W If a polymer a1) is used which is a homopolymer or copolymer at least partially prepared from vinyl alcohol and / or vinylphenol, it preferably has a weight average molecular weight (M) in the range of 500 to 100,000 g / mol, preferably 750 to 50,000 g / mol, more preferably 1,000 to 25,000 g / mol, even more preferably 1,000 to 10,000 g / mol. W )

[0060] Component a2) The aqueous acidic composition used in step 1) further comprises, as at least one component a2), at least one metal cation selected from the group of titanium ions, zirconium ions, hafnium ions, and mixtures thereof.

[0061] Preferably, the aqueous acidic composition used in step 1) comprises at least one component a2) in an amount ranging from 0.1 to 10 g / L, in each case calculated as metal, where component a2) is preferably selected from titanium ions, zirconium ions and mixtures thereof, most preferably zirconium ions. The content of component a2) can be monitored and determined by means of ICP-OES (Inductively Coupled Plasma Optical Emission Spectroscopy). This method is described in detail below. Preferably, when the aqueous acidic composition used in step 1) is applied by spraying, it comprises at least one component a2) in an amount ranging from 0.1 to 1.0 g / L, more preferably from 0.2 to 0.6 g / L, even more preferably from 0.2 to 0.4 g / L, in each case calculated as metal. Preferably, when the aqueous acidic composition used in step 1) is applied by roller coating, it comprises at least one component a2) in an amount in the range of 0.2 to 8.0 g / L, more preferably 0.5 to 7.5 g / L, even more preferably 0.7 to 5.0 g / L, and even more preferably 1.0 to 3.0 or 2.0 g / L, in each case calculated as metal.

[0062] Preferably, a precursor metal compound is used to generate the metal cations present in the composition as component a2). Preferably, the precursor metal compound is water-soluble. The solubility is determined at a temperature of 20°C and atmospheric pressure (1.013 bar).

[0063] Particularly preferred zirconium, titanium, and / or hafnium compounds are complex fluorides of these metals. The term "complex fluoride" includes singly and multiply protonated and deprotonated forms. It is also possible to use mixtures of such complex fluorides. Complex fluorides within the meaning of the present invention are, for example, complexes of zirconium, titanium, and / or hafnium formed with fluoride ions in the composition by coordination of fluoride anions to zirconium, titanium, and / or hafnium cations in the presence of water. Furthermore, carbonates and / or complex carbonates and / or lactates and / or, in particular, nitrates of zirconium, titanium, and / or hafnium can also be used. However, preferably, the cations are incorporated into the composition in the form of their complex fluorides.

[0064] Further optional components (components a3), a4) and / or a5)) The aqueous acidic composition may include additional components, as listed below. The term "further comprising," as used throughout this specification in reference to the components of the aqueous composition, means "in addition to the essential components." Thus, such "additional" components include ions other than the metal ions described above.

[0065] Optionally and preferably, the acidic aqueous composition used in step 1) further comprises at least one component a3), i.e., as at least one component a3), free fluoride anions. If free fluoride anions are present, they are preferably present in an amount in the range of 1 to 50 mg / L, more preferably 2 to 40 mg / L, even more preferably 3 to 30 mg / L, even more preferably 5 to 25 mg / L, in each case calculated as fluorine.

[0066] The acidic aqueous composition used in step 1) optionally, but preferably, contains free fluoride anions as component a3). These arise from the presence of component a2), i.e., in particular when complex fluorides of Ti, Zr, and / or Hf are present in the composition, but also or alternatively from the presence of other optional components, such as those described below, such as the incorporation of at least one water-soluble fluorine compound. Examples of such water-soluble fluorine compounds are fluorides (other than complex fluorides of Ti, Zr, and / or Hf) and hydrofluoric acid. The free fluoride content is determined using a fluoride ion-sensitive electrode according to the method disclosed in the "Method" section.

[0067] Optionally, but preferably, the acidic aqueous composition used in step 1) is molybdenum cations as at least one component a4), preferably in an amount ranging from 0.01 to 8.0 g / L, calculated as the metal, Further includes:

[0068] Preferably, in particular when the aqueous acidic composition used in step 1) is applied by spraying, it comprises at least one component a4) in an amount ranging from 0.01 to 0.2 g / L, more preferably from 0.01 to 0.1 g / L, even more preferably from 0.01 to 0.05 or 0.03 g / L, in each case calculated as metal. Preferably, in particular when the aqueous acidic composition used in step 1) is applied by roller coating, it comprises at least one component a4) in an amount ranging from 0.2 to 8.0 g / L, more preferably from 0.4 to 7.5 g / L, even more preferably from 0.5 to 6.0 g / L, in each case calculated as metal.

[0069] Preferably, the amount of component a4) is less than the amount of component a2).

[0070] To prepare an aqueous acidic composition, if the composition contains a4), preferably a water-soluble (at a temperature of 20° C. and atmospheric pressure (1.013 bar)) molybdenum salt is used. Preferably, the molybdenum ions are incorporated in the form of at least one molybdate, preferably at least one ammonium molybdate.

[0071] Optionally, the acidic aqueous composition used in step 1) further comprises at least one organosilane as optional component a5), preferably in an amount ranging from 10 to 500 ppm, more preferably from 20 to 100 ppm.

[0072] Examples include, for example, (3-aminopropyl)trimethoxysilane, (3-aminopropyl)triethoxysilane, N-2-aminoethyl-3-aminopropyltrimethoxysilane, (3-mercaptopropyl)trimethoxysilane, (3-mercaptopropyl)triethoxysilane, (3-glycidyloxypropyl)trimethoxysilane and / or (3-glycidyloxypropyl)triethoxysilane, and / or vinyltrimethoxysilane.

[0073] Other optional components Optionally, the aqueous acidic composition further comprises at least one metal cation selected from the group consisting of cations of metals from the first to third subgroups of the Periodic Table of the Elements (copper, zinc, and scandium groups), the fifth to eighth subgroups (vanadium, chromium, iron, cobalt, and nickel groups), including the lanthanides, and the second main group of the Periodic Table of the Elements (alkaline earth metals), lithium, bismuth, and tin. However, preferably, metal cations from the chromium, cobalt, and nickel groups are not used. The metal cations are generally introduced in the form of their water-soluble compounds, preferably as their water-soluble salts. Preferred cation(s) are selected from the group consisting of cations of cerium and other lanthanides, iron, calcium, copper, magnesium, manganese, niobium, tantalum, yttrium, vanadium, lithium, bismuth, zinc, and tin.

[0074] Optionally, the aqueous acidic composition further comprises at least one pH-adjusting substance, preferably selected from the group consisting of nitric acid, sulfuric acid, methanesulfonic acid, acetic acid, aqueous ammonia, sodium hydroxide and sodium carbonate, where nitric acid, aqueous ammonia and sodium carbonate are preferred. Depending on the pH value of the acidic aqueous composition, the compounds may be in a fully or partially deprotonated form, or in a protonated form.

[0075] Optionally, the aqueous acidic composition further comprises at least one complexing agent, an example of which is 1-hydroxyethane-1,1-diphosphonic acid (HEDP).

[0076] Optionally, the aqueous acidic composition further comprises at least one corrosion inhibitor. Examples include L-cysteine ​​and other amino acids, benzotriazole, and mixtures thereof. Preferably, the at least one corrosion inhibitor does not contain any type of metal ion.

[0077] Optionally, particularly when the aqueous composition is alkaline, the aqueous composition further comprises at least one organic acid, preferably at least one organic acid having at least two carboxylic acid groups and / or at least one organic acid having at least one carboxylic acid group and at least one additional functional group having at least one donor atom, such as an OH group, such as lactic acid. The presence of such a compound may help stabilize at least one metal ion in the composition, such as Zr cation.

[0078] Optionally, the aqueous acidic composition further comprises phosphate anions, preferably added in the form of phosphoric acid. Preferably, the phosphate anions are present in an amount ranging from 0.5 to 90 g / L, calculated as P2O5. The aqueous composition may further comprise at least one of the following components: one or more waxes, one or more wetting agents, and one or more defoaming agents.

[0079] Optional step 1a) After step 1), the surface of the substrate obtained after contacting in step 1) can be optionally rinsed, preferably with deionized water or tap water (optional step 1a)). If this step is performed, it is preferably performed before the drying or curing performed in step 1).

[0080] Method step 2) In step 2), at least one thermoplastic polymer material TM1 is applied at least partially onto the film or dried or cured layer obtained after step 1), wherein the at least one thermoplastic polymer material TM1 is i) applied in the form of a foil (option i)) or ii) applied in the molten state by injection onto the film or dried or cured layer obtained after step 1) (option ii)), forming a metal-plastic hybrid material. Preferably, option i) of step 2) is not performed by injection molding.

[0081] The formed foil obtained using the thermoplastic polymer material TM1 in step 2), first option i) preferably serves as a compatibilizer material for the thermoplastic polymer material TM2 that is optionally subsequently injected in optional step 3a).

[0082] Step 2), second option ii) and optional step 3a) each represent an injection molding step in which the thermoplastic polymer material TM1 (or TM2) in the case of step 3a) is injected directly onto the metal surface of the substrate to which the acidic aqueous composition has previously been applied in step 1).

[0083] Step 2) can be carried out continuously or discontinuously.

[0084] The substrate obtained after step 1) or after optional step 1a) is preferably heated before carrying out step 2), preferably to a temperature above the melting point of the thermoplastic material TM1 used.

[0085] Preferably, the thermoplastic polymer material TM1 used in step 2) and / or the thermoplastic polymer material TM2 used in optional step 3a) are applied in such a way that a vacuum is applied to bring the respective thermoplastic polymer material into contact with at least a portion, preferably the entire surface, of the substrate whose surface was in contact with the acidic aqueous composition in step 1), and to remove any air trapped between the surface of the substrate and the respective thermoplastic polymer material. Preferably, the temperature of the substrate and the respective thermoplastic polymer material applied thereto is maintained above a temperature that promotes bonding between the applied thermoplastic polymer material and the metal substrate. After the aforementioned heating, the substrate is preferably placed in an apparatus capable of applying the respective thermoplastic polymer material to the surface of the substrate, preferably a thermoforming apparatus capable of applying, for example, the thermoplastic polymer material TM1 as a foil. Alternatively, the substrate can first be placed in an apparatus in which the respective thermoplastic polymer material is applied, and then the substrate can be heated before the thermoplastic polymer material is placed thereon. Preferably, after the heated substrate is placed in the apparatus, or after the substrate is placed in the apparatus and then heated, the respective thermoplastic polymer material is placed on the substrate and optionally heated, e.g., in the case of step 2), option ii), the material is injected in a molten state. If the thermoplastic polymer material is heated, the heating can be achieved by, for example, infrared radiation.

[0086] The temperature to which the thermoplastic polymer material is heated is preferably selected so that the thermoplastic material has rubber elasticity. To this end, the thermoplastic material is preferably heated to a temperature above the glass transition temperature of the thermoplastic material if the thermoplastic material is an amorphous thermoplastic material, or above the melting point of the crystal if the thermoplastic material is a semi-crystalline thermoplastic material, but preferably below the melting point to avoid damage. After placing each thermoplastic polymer material on the substrate surface, and optionally after heating the material, a vacuum is preferably applied as described above. By applying the vacuum, the thermoplastic polymer material preferably adheres to the surface of the substrate and achieves a strong connection. Removing air that may be trapped between the surface of the substrate and the thermoplastic polymer material preferably results in a smooth surface without blistering. To apply the vacuum, the substrate may have an opening through which air can be removed. If the substrate does not have an opening, air between the substrate and the thermoplastic polymer material can also be removed at the edges of the thermoplastic polymer material. When removing air at the edges, it is preferable to remove air from at least two opposing sides, preferably around the entire periphery of each thermoplastic polymer material. A suitable vacuum pump can be used to apply the vacuum. When removing air from the edges of the thermoplastic polymer material, each thermoplastic polymer material is preferably secured in a device for applying a vacuum such that a gap is formed between the substrate and the edge of the thermoplastic polymer material and the vacuum is applied through the gap. By applying the vacuum, the thermoplastic polymer material preferably contacts the substrate uniformly over its entire surface, resulting in the formation of a uniform layer on the surface of the substrate.

[0087] After the thermoplastic polymer material is preferably contacted with the entire surface of the substrate, the temperature of the substrate and each thermoplastic polymer material is maintained at a temperature that promotes bonding between the thermoplastic material and the substrate, preferably above the melting point of the thermoplastic material. By maintaining the temperature, the thermoplastic material preferably chemically reacts with at least the functional groups of the water-soluble polymer originally present in the acidic aqueous composition, thereby achieving a stable bond between the surface of the substrate and each thermoplastic polymer material, and forming a composite member including a "metal layer" (the metal surface of the substrate) and a "polymer layer" (the applied thermoplastic material).

[0088] Preferably, before carrying out at least step 2), option ii), the substrate obtained after step 1), optionally 1a), is placed in a mold before carrying out step 3).

[0089] Optional step 3a) In optional step 3a), at least one thermoplastic polymer material TM2, which is identical to or different from the thermoplastic material TM1 applied in step 2) and which is present in a molten state, is at least partially injected onto the surface of the foil of metal-plastic hybrid material obtained after steps 2) and i).

[0090] If optional step 3a) is performed, the thermoplastic polymer material TM2 is preferably different from the thermoplastic polymer material TM1.

[0091] Optional step 3b) In optional step 3b), a further substrate S2 having at least one metal surface is applied onto the surface of the foil of metal-plastic hybrid material obtained after steps 2) and i) (or vice versa), said surface being at least partly made of aluminum and / or at least one aluminum alloy and having been subjected to process step 1) of the method, i.e. by applying an acidic aqueous composition.

[0092] Thermoplastic polymer materials TM1 and TM2 Thermoplastic polymer material TM1 may be the same as or different from thermoplastic polymer material TM2, and is preferably different.

[0093] Preferably, the thermoplastic polymer material TM1 is capable of chemically bonding with the functional groups of the water-soluble polymer originally present in the acidic aqueous composition used in step 1).

[0094] Preferably, the thermoplastic polymer material TM1 is selected from polyamide, polyester such as PET and / or PBT, polyurethane, polycarbonate, polyolefin such as polypropylene and polyethylene, and mixtures thereof. It is also possible to use recycled thermoplastic polymer materials, such as recycled polyamide. Preferably, the polyamide is selected from PA6, PA66, PA66 / 6, PA6.10, PA6.12, PA12, PA9T, PA6I / 6T, PA6T / 6I, PA6 / 6.36, and combinations thereof. Most preferred are polyesters, such as PET and / or PBT, and polyamide. Preferably, at least one polyester is applied as the at least one thermoplastic polymer material TM1 via step 2) (i) or (ii).

[0095] The thermoplastic polymer material TM1, such as a polyamide, can be used in a compounded form with at least one additive, for example at least one rubber, such as EPDM (ethylene propylene diene monomer) rubber, to improve the properties of the thermoplastic polymer material, in particular to reduce its water uptake. Alternatively or additionally, the thermoplastic polymer material TM1 and / or TM2, preferably TM2, can (i) optionally comprise at least one fiber, such as glass fiber, carbon fiber, aramid fiber, and combinations thereof, and / or (ii) optionally comprise a polyether block polyamide, such as a polyether diamine and an aliphatic C4-C 40 Dicarboxylic acids and / or C6-C 12 Copolymerizates with lactams, such as caprolactam or lauryllactam, aliphatic C4-C 10 Diamines and Aliphatic C4-C40 Copolymerizates with dicarboxylic acids, C6-C 12 and / or (iii) optionally, at least one impact modifier, such as maleic anhydride graft copolymers of ethylene with at least one of an α-olefin, a (meth)acrylic acid ester, and (meth)acrylic acid, copolymers of maleic anhydride with ethylene and at least one of a (meth)acrylic acid ester, styrene maleic anhydride, or maleic anhydride graft polypropylene.

[0096] Preferably, the thermoplastic polymer material TM2 is selected from polyamides, polyesters such as PET and / or PBT, polyolefins such as polypropylene and polyethylene, and mixtures thereof. Preferably, the polyamide is selected from PA6, PA66, PA66 / 6, PA6.10, PA6.12, PA12, PA9T, PA6I / 6T, PA6T / 6I, PA6 / 6.36, and combinations thereof. It is also possible to use recycled thermoplastic polymer materials, such as recycled polyamides.

[0097] Preferably, the thermoplastic polymer material TM1 has a melting point in the range of 80° C. to 280° C. For example, polyolefins may have a melting point of 80° C., while polyamides have significantly higher melting points, for example 280° C.

[0098] Preferably, the thermoplastic polymer material TM2 has a melting point in the range defined for the thermoplastic polymer material TM1.

[0099] Metal-plastic hybrid materials obtainable by the method of the present invention A further subject of the invention is a metal-plastic hybrid material obtainable by the method according to the invention.

[0100] All preferred embodiments mentioned herein above in relation to the inventive method and its preferred embodiments are also preferred embodiments of the inventive metal-plastic hybrid material obtainable by said method.

[0101] Preferably, the dry layer thickness of the layer obtained from drying or curing the film obtainable from applying the aqueous acidic composition, as defined in relation to step 1) of the method of the present invention at least partially onto the metal surface, is in the range of 100 to 1000 nm, more preferably 150 to 750 nm, in particular 250 to 550 nm.

[0102] Methods of using acidic aqueous compositions A further subject of the present invention is the use of an acidic aqueous composition as defined in connection with step 1) of the method of the present invention for adhering a metal surface of a substrate, at least partly made of aluminum and / or at least one aluminum alloy, to a thermoplastic polymer material, e.g. a thermoplastic material TM1, present on said surface in the form of a foil or applied thereto by injection molding, preferably by utilizing the method of the present invention.

[0103] All preferred embodiments described herein above in relation to the inventive method, the inventive metal-plastic hybrid material obtainable by said method, and preferred embodiments thereof, are also preferred embodiments of the inventive method of use.

[0104] Metal-plastic hybrid materials A further subject of the present invention is such a metal-plastic hybrid material, namely a substrate S1 having at least one metal surface made at least in part from at least one aluminum and / or at least one aluminum alloy; a film or dried layer or cured layer at least partially applied onto the metal surface, which film or dried layer or cured layer is obtainable from at least partially applying onto the metal surface an aqueous acidic composition as defined in relation to said step 1) of the method of the present invention; at least one thermoplastic polymer material TM1, preferably in the form of a foil or in the form resulting from injection molding, which is applied at least partially onto the film or the dried layer or the cured layer, in each case as defined in step 2) of the method of the invention, Optionally, at least one thermoplastic polymer material TM2, identical or different to the thermoplastic polymer material TM1, applied at least partially onto the at least one thermoplastic polymer material TM1 in a form obtainable from injection molding, the thermoplastic polymer material TM1 being applied in the form of a foil, or Optionally, furthermore, a substrate S2 having at least one metal surface, said surface being at least partially made of aluminum and / or at least one aluminum alloy, said substrate having a film or a dry layer or a hardened layer at least partially applied on said metal surface, said film or a dry layer or a hardened layer being obtainable by applying an aqueous acidic composition as defined in connection with step 1) of the method of the present invention, said film or a dry layer or a hardened layer being at least partially present on said metal surface of the substrate S2 being located adjacent to at least one thermoplastic polymer material TM1, with the proviso that the thermoplastic polymer material TM1 is applied in the form of a foil. A metal-plastic hybrid material comprising:

[0105] Preferably, a metal-plastic hybrid material is obtainable by the method of the present invention.

[0106] Preferably, the thermoplastic polymer material TM1, present in the form of a laminate or in a form obtainable from injection molding, has a total thickness ranging from 200 to 800 μm.

[0107] All preferred embodiments described herein above in relation to the inventive method, the inventive metal-plastic hybrid material obtainable by said method, the inventive use method and their preferred embodiments are also preferred embodiments of such inventive metal-plastic hybrid material.

[0108] Preferably, the film or dry or cured layer, preferably the dry layer, applied at least partially onto the metal surface of the metal-plastic hybrid material comprises: Due to the presence of component a2) in the acidic aqueous composition used, in each case calculated as metal, 0.1 to 40 mg / m 2 , more preferably 0.2 to 30 mg / m 2 , and even more preferably 0.5 to 20 mg / m 2 , and even more preferably 1.0 to 15 mg / m 2 , and even more preferably 1.5 to 10 mg / m 2 , especially 2.0 to 8 mg / m 2 of zirconium and / or titanium and / or hafnium, preferably zirconium and / or titanium, more preferably zirconium, Calculated as metal, 0 or 0.1 to 40 mg / m 2 , more preferably 0 or 0.2 to 30 mg / m 2 , and even more preferably 0 or 0.5 to 20 mg / m 2 , and even more preferably 0 or 1.0 to 15 mg / m 2 , and even more preferably 0 or 1.5 to 10 mg / m 2 , especially 2.0 to 8 mg / m 2 Molybdenum The coating mass was determined by XRF (X-ray fluorescence spectroscopy).

[0109] If at least one thermoplastic polymer material TM2 is present in the metal-plastic hybrid material, then preferably optional step 3a) of the method of the invention is carried out, in which case in step 2) thermoplastic polymer material TM1 is applied in the form of a foil and in step 3a) thermoplastic polymer material TM2 is applied on top by injection moulding.

[0110] If a further substrate S2 is present in the metal-plastic hybrid material, which also has at least one metal surface made at least partially from aluminum and / or at least one aluminum alloy, then optional step 3b) of the method of the present invention is preferably carried out, in which the thermoplastic polymer material TM1 is applied in the form of a foil in step 2), and in step 3b) the substrate S2, whose at least one metal surface has also been treated with the acidic aqueous composition according to step 1), is applied with its treated surface adjacent to the foil made from the thermoplastic polymer material TM1, so that an overall sandwich structure is formed, in which the foil made using TM1 is sandwiched between the two metal surfaces of the two substrates S1 and S2, each of the two metal surfaces bearing the coating layer obtained by treatment step 1). Preferably, when the metal-plastic hybrid material comprises a further substrate S2, it can be considered as a sandwich structure comprising two substrates S1 and S2, each of which is attached to one surface of the thermoplastic material TM1 present in the form of a foil by means of an adhesive film or a dried or hardened layer resulting from the application of an aqueous acidic composition as defined in relation to the preceding step 1) of the method of the present invention. Preferably, the substrates S1 and S2 are each sheets or coils made of aluminum and / or its alloys. Each coil or sheet can have a total thickness ranging from 0.2 mm to 3 mm, depending on the desired application.

[0111] How to use metal-plastic hybrid materials A further subject of the invention is the use of said metal-plastic hybrid material or of a metal-plastic hybrid material obtainable by the method of the invention as a component in the automotive, construction or electronics industry.

[0112] In this specification, all preferred embodiments described above in connection with the inventive method, the inventive metal-plastic hybrid material obtainable by said method, the inventive use method as described above, such inventive metal-plastic hybrid material, and their preferred embodiments, are also preferred embodiments of the inventive use method of the metal-plastic hybrid material.

[0113] In particular, the metal-plastic hybrid material in which the substrate S1 and optionally the substrate S2 are foils can be used in e-mobility applications, in the manufacture of parts for the electronics industry, and / or in the manufacture of automotive parts, in particular where weight reduction is required. Further possible applications include lidar and EMI shielding applications, the manufacture of automotive panel controls, the manufacture of battery housings, and the manufacture of protective panels for batteries.

[0114] method 1. Cross-cut test according to DIN EN ISO 2409 (06-2013) A cross-cut test according to DIN EN ISO 2409 (06-2013) is used to check the adhesive strength. The cutter spacing is 3 mm. The evaluation is based on a characteristic cross-cut value ranging from 0 (very good adhesion) to 5 (very poor adhesion). The test is performed three times for each sample and an average value is determined.

[0115] 2.Average molecular weight M W and M n Decision Number average molecular weight and mass average molecular weight (M n and M W) are measured according to the following protocol, respectively: Samples are analyzed by SEC (size exclusion chromatography) equipped with a MALS detector. Absolute molar masses are measured by setting the dn / dC value to 0.1875 mL / g, to ensure a recovery of approximately 90%. The polymer sample is dissolved in the mobile phase, and the resulting solution is filtered through a 0.45 μm Millipore filter. The elution conditions are as follows: Mobile phase: 100% by volume of H2O, 0.1 M NaCl, 25 mM NaH2PO4, 25 mM Na2HPO4; 100 ppm NaN3; flow rate: 1 mL / min; column: Varian Aquagel OH mixed H, 8 μm, 3*30 cm; detection: RI (concentration detector Agilent) + MALLS (multi-angle laser light scattering) Mini Dawn Tristar + UV at 290 nm; sample concentration: approximately 0.5% by weight in the mobile phase; injection loop: 100 μL. The obtained M n and M W From the value of , the polydispersity P can be calculated.

[0116] 3. Determination of free fluoride content Free fluoride content is determined using a fluoride ion-selective electrode. The electrode is calibrated using at least three master solutions with known fluoride concentrations. The calibration process generates a calibration curve. This curve is then used to determine the fluoride content.

[0117] 4. ICP-OES The amount of a specific element, such as zirconium, titanium, or hafnium, in a sample under analysis is determined using inductively coupled plasma optical emission spectroscopy (ICP-OES) in accordance with DIN EN ISO 11885 (dated September 1, 2009). The sample is thermally excited in an argon plasma generated by a radio-frequency magnetic field, and the light emitted by electronic transitions is visualized as spectral lines of the corresponding wavelengths and analyzed using an optical system. There is a linear relationship between the intensity of the emitted light and the concentration of the element in question. Prior to implementation, calibration measurements are performed using known element standards (reference standards) as a function of the specific sample under analysis. These calibrations can be used to determine the concentration of unknown solutions, such as titanium, zirconium, or hafnium.

[0118] 5. Tensile strength Tensile strength was measured according to ISO 527-1:2012. [Example]

[0119] The following examples further illustrate the present invention but are not to be construed as limiting its scope.

[0120] 1. Preparation of Acidic Aqueous Coating Composition 1.1 Acidic aqueous compositions A1 to A3 were prepared (1 L each). All aqueous compositions contained HZrF in an amount corresponding to the ppm value of zirconium, calculated as the metal, as shown in Table 1a below. All aqueous compositions further contained heptamolybdate in an amount corresponding to the ppm value of molybdenum, calculated as the metal, as shown in Table 1 below. All compositions were chromium-free and contained free fluoride anions. Each composition further contained one of the following water-soluble polymers P1 to P3: P1: M over 150,000 g / mol W a commercially available polyacrylic acid having P2: Copolymer of maleic acid and vinyl methyl ether, P3: Copolymer of maleic acid and ethylene.

[0121] [Table 1]

[0122] 1.2 Acidic aqueous compositions A4 to A6 were also prepared (1 L each). All aqueous compositions contained HZrF in an amount corresponding to the ppm value of zirconium, calculated as the metal, as shown in Table 1b below. All aqueous compositions further contained heptamolybdate in an amount corresponding to the ppm value of molybdenum, calculated as the metal, as shown in Table 1b below. All compositions were chromium-free and contained free fluoride anions. Each composition further contained one of the water-soluble polymers P1 to P3 previously identified herein.

[0123] [Table 2]

[0124] 2. Pretreatment 2.1 An aluminum alloy substrate (substrate T1; 5754 AlMg3) was used as the substrate in a coil shape. 5754 AlMg3 is an aluminum-magnesium alloy substrate.

[0125] The substrate was cleaned using a commercially available alkaline product, Gardoclean® S 5160 (60-70°C). This was followed by two rinses with tap water (30 seconds each). A pickling step was then performed using the commercially available Gardoclean® S 5240 / 2. This was followed by a rinse with tap water (30 seconds) and deionized water (30 seconds).

[0126] Thereafter, a contacting step was carried out to form a conversion coating layer having adhesion-promoting properties on the surface of the substrate, i.e., the surface of the substrate was contacted with one of the acidic aqueous compositions A1 to A3 described above in item 1. The contacting step was carried out in each case for 60 seconds by spraying one of the acidic aqueous compositions onto the surface of the substrate. The acidic aqueous composition was heated to 25°C before spraying.

[0127] After the contacting step, air was blown onto the surface, followed by a drying step (15 minutes at 60 to 70° C.) The thickness of the resulting dried layer was in the range of 50 to 200 nm.

[0128] 2.2 An aluminum alloy substrate (substrate T2; AA 6060) was used as the substrate.

[0129] The substrate was cleaned using the commercially available alkaline product Gardoclean® T 5281 A (55°C). This was followed by two washes with tap water (30 seconds each). Next, an acid pickling step was performed using the commercially available product Gardacid® P 4432. This was followed by three rinses with tap water (60 seconds each).

[0130] A contacting step was then carried out to form a conversion coating layer having adhesion-promoting properties on the surface of the substrate, i.e., the surface of the substrate was contacted with one of the acidic aqueous compositions A4 to A6 described above in section 1.2. The contacting step was carried out by spraying one of the acidic aqueous compositions onto the surface of the substrate for 60 seconds in each case. The acidic aqueous composition was heated to 30°C before spraying.

[0131] The contact step was followed by three rinses with tap water (60 seconds each).

[0132] Then, air was blown onto the film, followed by a drying step (100°C for 8 minutes).

[0133] 3. Preparation of Metal-plastic Hybrid Materials 3.1 A mixture of polybutylene terephthalate (PBT) as thermoplastic polymer material and glass fibers (commercial product Tecadur® PBT-GF30) was applied by injection molding at temperatures between 180 and 240°C directly onto the surface of the substrate obtained after the pretreatment described in section 2.1. The laminates produced by injection molding had thicknesses (of the plastic layer) ranging from 400 μm to 2 cm, depending on the desired application.

[0134] 3.2 Sandwich structures were also prepared in the same way as described in section 3.1, except that Tecadur® PBT-GF30 was injected between the two surfaces of two substrates obtained after the pretreatment described in section 2.1.

[0135] 3.3 A mixture of polybutylene terephthalate (PBT) as thermoplastic polymer material and glass fibers (commercial product Tecadur® PBT-GF30) was applied by injection molding directly onto the surface of the substrate obtained after the pretreatment described in section 2.2 at temperatures between 180 and 240°C. The laminates obtained by injection molding had thicknesses (of the plastic layer) ranging from 400 μm to 2 cm, depending on the desired application.

[0136] 4. Properties of the obtained metal-plastic hybrid material 4.1 Many properties of the products obtained by the methods described in the preceding sections 3.1 and 3.2 were investigated. These properties were determined according to the test methods previously described in this specification. The results are shown in Tables 2 and 3. In particular, the adhesive strength was investigated.

[0137] [Table 3]

[0138] As can be seen from Table 2, excellent adhesion of PBT to the metal substrate was achieved in all cases.

[0139] [Table 4]

[0140] A peel test was conducted on the sandwich structure, and no peeling was observed.

[0141] 4.2 Many properties of the product obtained by the method described in the previous section 3.3 were investigated. These properties were determined according to the test methods described in this specification. The results are shown in Table 4. In particular, the adhesive strength was investigated.

[0142] [Table 5]

[0143] As can be seen from Table 4, excellent adhesion of PBT to the metal substrate was achieved in all cases.

Claims

1. A method for preparing a metal-plastic hybrid material, said material comprising a substrate S1 having at least one metal surface and at least one thermoplastic material applied onto said metal surface of said substrate S1, said method comprising at least steps 1) and 2) and optionally step 3a) or 3b), i.e. 1) applying an aqueous acidic composition at least partially onto at least one metal surface of said substrate S1 to at least partially form a film on said surface, and optionally drying or curing said film to form a dried or cured layer, the metal surface is made at least in part of aluminum and / or at least one aluminum alloy, the acidic aqueous composition comprises, in addition to water, as at least one component a1), at least one water-soluble polymer having at least one functional group selected from acid groups, hydroxyl groups, amino groups, and mixtures thereof; as at least one component a2), at least one metal cation selected from the group consisting of titanium ions, zirconium ions, hafnium ions, and mixtures thereof; and as at least one component a3), free fluoride anions. 2) applying at least one thermoplastic polymer material TM1 at least partially onto said film or dried or cured layer obtained after step 1), said at least one thermoplastic polymer material TM1 is applied i) in the form of a foil or ii) by injection in the molten state onto said film or dried or cured layer obtained after step 1) to form a metal-plastic hybrid material; and 3a) optionally injecting at least one thermoplastic polymer material TM2, present in the molten state and identical or different to the thermoplastic material TM1 applied in step 2), at least partially onto the surface of the foil of metal-plastic hybrid material obtained after steps 2) and i); or 3b) optionally applying a further substrate S2 having at least one metal surface onto the surface of the foil of metal-plastic hybrid material obtained after steps 2) and i) or vice versa, said surface being at least partly made of aluminum and / or at least one aluminum alloy and having been subjected to the treatment of step 1) of the method. A method comprising:

2. 2. The method of claim 1, wherein the acidic aqueous composition used in step 1) has a pH value in the range of 0.1 to <7.0, preferably 0.5 to 6.5, more preferably 1.0 to 6.0, even more preferably 1.5 to 5.5, even more preferably 2.0 to 5.0, even more preferably 2.5 to 4.5, even more preferably 3.0 to 4.0, and most preferably >3.0 to <3.

7.

3. 3. The method according to claim 1 or 2, wherein the at least one water-soluble polymer used as component a1) is present in the acidic aqueous composition in an amount in the range of 0.05 to 2.0 g / L, preferably 0.10 to 1.8 g / L, more preferably 0.12 to 1.6 g / L, even more preferably 0.14 to 1.5 g / L, even more preferably 0.16 to 1.4 g / L, even more preferably 0.18 to 1.2 g / L, and most preferably 0.20 to 1.0 g / L.

4. 3. The method according to claim 1 or 2, wherein the at least one water-soluble polymer used as component a1) has at least one functional group selected from carboxylic acid groups, phosphonic acid groups, sulfonic acid groups, hydroxyl groups, amino groups, and mixtures thereof, more preferably selected from carboxylic acid groups, hydroxyl groups, amino groups, and mixtures thereof, even more preferably selected from carboxylic acid groups.

5. 10. The method according to claim 1, wherein the at least one water-soluble polymer used as component a1) is a homopolymer or copolymer obtainable from the polymerization of at least one ethylenically unsaturated monomer, preferably a homopolymer or copolymer obtainable from the polymerization of at least one vinyl and / or (meth)acrylic monomer, at least some of which monomers carry at least one functional group according to claim 4.

6. The at least one water-soluble polymer used as component a1) is preferably a (meth)acrylic acid homopolymer, in particular an acrylic acid homopolymer, a copolymer of (meth)acrylic acid and at least one ethylenically unsaturated monomer other than (meth)acrylic acid, in particular a copolymer of (meth)acrylic acid and maleic acid, a copolymer of maleic acid and at least one ethylenically unsaturated monomer other than maleic acid, in particular a copolymer of maleic acid and at least one alkyl vinyl ether, such as ethylene and / or propylene and / or methyl vinyl ether, a copolymer of vinylphosphonic acid and at least one ethylenically unsaturated monomer other than vinylphosphonic acid, in particular a copolymer of (meth)acrylic acid and vinylphosphonic acid, and a copolymer of (meth)acrylic acid and vinylphosphonic acid.

3. The method according to claim 1 or 2, wherein the modified vinyl monomer is selected from copolymers of acrylic acid, vinylphosphonic acid and maleic acid, vinyl alcohol homopolymers, copolymers of vinyl alcohol and at least one ethylenically unsaturated monomer other than vinyl alcohol, vinylphenol homopolymers, copolymers of vinylphenol and at least one ethylenically unsaturated monomer other than vinylphenol, copolymers of vinylmercaptoethanol and at least one ethylenically unsaturated monomer other than vinylmercaptoethanol, homopolymers and copolymers of vinylphenol modified with at least one amine, preferably at least one primary amine, such as N-ethanolamine and / or N-methylglucamine, and mixtures thereof.

7. the at least one water-soluble polymer used as component a1) is selected from (meth)acrylic acid homopolymers, in particular acrylic acid homopolymers, copolymers of (meth)acrylic acid and at least one ethylenically unsaturated monomer other than (meth)acrylic acid, in particular copolymers of (meth)acrylic acid and maleic acid, copolymers of maleic acid and at least one ethylenically unsaturated monomer other than maleic acid, in particular copolymers of maleic acid and at least one alkyl vinyl ether, such as ethylene and / or propylene and / or methyl vinyl ether, vinyl alcohol homopolymers, copolymers of vinyl alcohol and at least one ethylenically unsaturated monomer other than vinyl alcohol, homopolymers and copolymers of vinylphenols modified with at least one amine, preferably at least one primary amine, such as N-ethanolamine and / or N-methylglucamine, and mixtures thereof, 3. The method according to claim 1 or 2, wherein the polymer is preferably selected from N-methylglucamine-modified poly(vinylphenol), N-ethanolamine-modified poly(vinylphenol), poly(maleic acid-co-vinyl methyl ether), poly(maleic acid-co-acrylic acid), polyacrylic acid, poly(vinylphosphonic acid-co-acrylic acid), poly(acrylic acid-co-maleic acid-co-vinylphosphonic acid), poly(acrylic acid-co-maleic acid-co-vinylmercaptoethanol), and mixtures thereof.

8. 3. The method according to claim 1 or 2, wherein the aqueous acidic composition used in step 1) comprises at least one component a2) in an amount ranging from 0.1 to 10.0 g / L, in each case calculated as the metal, and component a2) is preferably selected from titanium ions, zirconium ions and mixtures thereof, most preferably selected from zirconium ions; if the aqueous acidic composition used in step 1) is applied by spraying, it comprises the at least one component a2) in an amount ranging from 0.1 to 1.0 g / L, more preferably from 0.2 to 0.6 g / L, even more preferably from 0.2 to 0.4 g / L, in each case calculated as the metal; and if the aqueous acidic composition used in step 1) is applied by roller coating, it comprises the at least one component a2) in an amount ranging from 0.2 to 8.0 g / L, more preferably from 0.5 to 7.5 g / L, even more preferably from 0.7 to 5.0 g / L, even more preferably from 1.0 to 3.0 or 2.0 g / L, in each case calculated as the metal.

9. 3. The method according to claim 1 or 2, wherein the acidic aqueous composition used in step 1) further comprises molybdenum cations as at least one component a4), preferably in an amount ranging from 0.01 to 8.0 g / L; if the aqueous acidic composition used in step 1) is applied by spraying, it comprises the at least one component a4) in an amount preferably ranging from 0.01 to 0.2 g / L, more preferably from 0.01 to 0.1 g / L, even more preferably from 0.01 to 0.05 or 0.03 g / L, in each case calculated as the metal; and if the aqueous acidic composition used in step 1) is applied by roller coating, it comprises the at least one component a4) in an amount preferably ranging from 0.2 to 8.0 g / L, more preferably from 0.4 to 7.5 g / L, even more preferably from 0.5 to 6.0 g / L, in each case calculated as the metal.

10. 3. The method according to claim 1 or 2, wherein the at least one thermoplastic polymer material TM1 and the at least one thermoplastic polymer material TM2 are independently selected from polyamides, polyesters, in particular PET and / or PBT, polyurethanes, polycarbonates, polyolefins, in particular polypropylene and polyethylene, and mixtures thereof, preferably the at least one thermoplastic polymer material TM1 is selected from polyesters, in particular PET and / or PBT.

11. A metal-plastic hybrid material obtainable by the method according to claim 1.

12. 10. Use of an acidic aqueous composition as defined in claim 1 for adhering a metal surface of a substrate, at least in part made of aluminum and / or at least one aluminum alloy, to a thermoplastic polymer material present on said surface in the form of a foil or applied to said surface by injection molding.

13. a substrate S1 having at least one metal surface made at least in part from at least one aluminum and / or at least one aluminum alloy; a film or dry layer or hardened layer at least partially applied onto the metal surface, the film or dry layer or hardened layer being obtainable from at least partially applying onto the metal surface an aqueous acidic composition as defined in relation to step 1) in claim 1; at least one thermoplastic polymer material TM1 in the form of a foil or in a form obtainable from injection molding, which is applied at least partially onto the film or the dried layer or the cured layer, preferably as defined in step 2) of claim 1, Optionally, furthermore, at least one thermoplastic polymer material TM2 identical or different to said thermoplastic polymer material TM1 and applied at least partially on said at least one thermoplastic polymer material TM1 in a form obtainable from injection molding, said thermoplastic polymer material TM1 being applied in the form of a foil, or Optionally, furthermore, a substrate S2 having at least one metal surface, said surface being at least partly made of aluminum and / or at least one aluminum alloy, said substrate having a film or a dry layer or a hardened layer at least partly applied on said metal surface, said film or a dry layer or a hardened layer being obtainable by applying an aqueous acidic composition as defined in connection with step 1) of claim 1, said film or a dry layer or a hardened layer being at least partly present on said metal surface of the substrate S2 being located adjacent to at least one thermoplastic polymer material TM1, with the proviso that said thermoplastic polymer material TM1 is applied in the form of a foil. A metal-plastic hybrid material comprising:

14. at least said film or dried layer or cured layer obtainable from applying an aqueous acidic composition to the metal surface of the substrate S1, preferably the dried layer or cured layer has a dry layer thickness in the range of 100 to 1000 nm and / or said film or dried layer or cured layer obtainable from applying an aqueous acidic composition to the metal surface of the substrate S1, preferably the dried layer or cured layer: Due to the presence of component a2) in the acidic aqueous composition used, in each case calculated as metal, 0.1 to 50 mg / m ２ , more preferably 0.2 to 30 mg / m ２ , and even more preferably 0.5 to 20 mg / m ２ , and even more preferably 1.0 to 15 mg / m ２ , and even more preferably 1.5 to 10 mg / m ２ , especially 2.0 to 8 mg / m ２ of zirconium and / or titanium and / or hafnium, preferably zirconium and / or titanium, more preferably zirconium, Calculated as metal, 0 or 0.1 to 40 mg / m ２ , more preferably 0 or 0.2 to 30 mg / m ２ , and even more preferably 0 or 0.5 to 20 mg / m ２ , and even more preferably 0 or 1.0 to 15 mg / m ２ , and even more preferably 0 or 1.5 to 10 mg / m ２ , especially 2.0 to 8 mg / m ２ Molybdenum 14. The metal-plastic hybrid material of claim 11 or 13, having a coating mass determined by XRF (X-ray fluorescence spectroscopy) of:

15. Use of the metal-plastic hybrid material according to claim 11 or 13 as a part in the automotive, construction or electronics industry.

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