Coating composition

Abstract

The invention relates to a composition for coating metal surfaces, comprising a binding agent which comprises a phenolic resin, an epoxy resin, in particular phenoxy resin, a polyester resin (soft resin) and a polyisocyanate, further comprising at least one conductive pigment, a corrosion resistant pigment and a solvent. The coating layer obtained from the composition by drying is corrosion-resistant, non-flammable, forming-compatible and weldable.

Description

[0001] Coating composition

[0002] The application relates to a composition for coating metal surfaces, in particular for battery boxes of battery-powered vehicles. Furthermore, the application relates to a method for coating metal surfaces, a sheet coated with the composition, an article coated with the composition, and a battery box with a coated surface.

[0003] Battery-powered vehicles enable environmentally friendly individual transport. To further increase the safety of battery-powered vehicles, it is necessary to effectively protect the vehicle battery from corrosion and mechanical damage. Furthermore, it is important to prevent premature flames from igniting and endangering vehicle occupants or the vehicle's interior in the event of battery overheating.

[0004] To achieve these goals, batteries are typically installed in battery boxes, usually made of steel. It is particularly important to provide suitable corrosion protection and protection against thermal events in the event of battery overheating. Therefore, state-of-the-art techniques include incorporating complex insulation layers into the battery, or applying multi-layer coatings to the exterior of the battery box, with the first layer usually being applied as a cathodic dip coating (CDP). The coatings should ideally exhibit suitable setting behavior during the screw connection and be tolerant to damage during the logistics process.

[0005] To protect the battery of an electric vehicle, the following option is known from the state of the art:

[0006] DE 102018203921 A1, for example, discloses a motor vehicle whose body or battery housing is provided with an intumescent fire protection coating which, in particular, comprises polyurethane which intumescents in the event of a fire.

[0007] Other state-of-the-art coating systems are known for use in vehicle construction:

[0008] EP 2 016 138 discloses a corrosion protection system for metal, the composition containing a binder, in particular a polyester resin. EP 1 030 894 discloses a corrosion protection composition comprising a binder made of polyester resins and / or epoxy resins.

[0009] However, there is still a need for environmentally friendly, easy-to-process compositions for coating metal surfaces, in particular battery boxes, which are corrosion-resistant, formable, weldable and, in particular, non-flammable.

[0010] The object of the invention is therefore to provide a coating composition which enables improved protection of a vehicle battery and increases the operational reliability of a battery-powered vehicle.

[0011] This problem is solved by the features of claim 1.

[0012] To achieve the object, a composition for coating metal surfaces is disclosed, which comprises the following components: a) a binder comprising

[0013] - a phenolic resin with 2 to 15 wt.%,

[0014] - an epoxy resin with 1 to 10 wt.%,

[0015] - a polyester resin with 0.1 to 5 wt.%,

[0016] - a polyisocyanate with 1 to 10 wt.%, b) at least one conductive pigment with 50 to 90 wt.%, and

[0017] - a corrosion protection pigment with 0.1 to 15 wt.%, where all weight percentages are based on the solids and c) a solvent of 5 - 80 wt.% based on the total composition.

[0018] This composition allows for a particularly environmentally friendly coating of metal surfaces.

[0019] The solids content, i.e. the content of non-volatile components, is determined according to DIN EN ISO 3251:2019. For this purpose, 1 g of the composition is evaporated for 1 hour at 120°C in a convection oven and then weighed. This definition of solids content is used for all subsequent data. After the composition has been applied and dried or cured, the solvent evaporates, forming a dry coating layer. The binder consists of several components. Phenolic resins are synthetic resins produced by polycondensation of phenols and aldehydes, particularly formaldehyde. Epoxy resins are synthetic resins that contain an epoxy group that opens and crosslinks upon curing. Polyester resins are synthetic resins produced by polycondensation of di- or polyhydric alcohols and dicarboxylic acids. Polyisocyanates are organic compounds that contain two or more isocyanate groups and are therefore highly reactive.Addition reactions occur during drying. Crosslinking of the components leads to the formation of a matrix. The binder thus forms a polymeric thermosetting matrix. The pigments are embedded in the matrix. The conductive pigment consists of electrically conductive particles.

[0020] The composition is particularly suitable for a coating with a dry film thickness of 2 to 20 pm.

[0021] The coating layer exhibits good adhesion to a wide variety of surfaces, with metal surfaces made of aluminum, aluminum alloy systems, or steel, especially electrolytically galvanized steel, hot-dip galvanized steel, zinc / magnesium galvanized steel, zinc / aluminum galvanized steel, zinc / iron galvanized steel, or ungalvanized steel, being particularly suitable for coating with the composition. The composition is suitable for coating various steel grades, e.g., deep-drawing grades and also for ultra-high-strength materials.

[0022] The coating layer provides high corrosion protection and prevents the development of surface, contact, and flange corrosion. The composition is therefore particularly well-suited for areas with mixed constructions made of different materials where contact corrosion is to be prevented. Since the composition is suitable for coating a metal strip, corrosion protection can also be achieved in areas that cannot be reached by subsequent painting, such as flange areas. It is also possible to use the composition as a replacement for a cathodic dip coating.

[0023] Another advantage is that the paint layer is flame-resistant. In particular, the paint layer does not ignite even on red-hot metal and does not continue to burn spontaneously. Thus, the paint layer is non-flammable when directly exposed to temperatures of approximately 950°C and above. This can be determined, for example, by heating a coated metal with a Bunsen burner.

[0024] The resulting coating can be further processed in a variety of ways. The coating is suitable for welding (resistance spot welding), especially with 50 Hz processes, and can be screwed and bonded, even with high-strength adhesives. Furthermore, the coating can be phosphated and cathodic dip-coated without reacting with the phosphate coating itself. A coated metal sheet can also be deep-drawn without additional oiling, if necessary, without damaging the coating.

[0025] Furthermore, the coating is not susceptible to electrostatic charging. It is also chemically resistant to alkaline cleaners, mild acids, and organic solvents.

[0026] Because the resulting coating layer is highly adhesive, easily formable, particularly flame-resistant or non-flammable, corrosion-resistant, and easily weldable, the composition is particularly well-suited for coating battery boxes. Other applications in the electrical or construction industries are also possible.

[0027] Preferred developments of the invention are disclosed in the subclaims.

[0028] Particularly good welding properties are achieved when the conductive pigment contains or consists of zinc and / or aluminum. These conductive pigments also improve corrosion protection. The conductive pigments in powder form are particularly suitable.

[0029] A composition in which the conductive pigment is spherical zinc powder is particularly suitable. Weldability is particularly improved when the particle size d(100) is between 35 pm and 45 pm, and / or d(99) is between 20 pm and 25 pm, and / or d(50) is between 3.6 pm and 4.7 pm. The particle size distribution can be determined by laser diffraction according to ISO 13320:2020.

[0030] If a portion of the conductive pigments protrudes above the level of the paint layer, weldability is improved. Weldability is therefore also improved if 0.001 wt.% to 1.0 wt.% of the conductive pigment particles have a particle size of 20 μm to 45 μm, particularly a particle size of 20 μm to 35 μm. The particle size can be measured according to ISO 3549:1995.

[0031] For particularly good welding suitability, the conductive pigment can be contained at 50.0 wt.% to 90.0 wt.%, in particular at 60.0 wt.% to 85.0 wt.%, preferably at 70.0 wt.% to 80.0 wt.%, based on the solids.

[0032] To improve the corrosion protection of the paint layer, the composition contains at least one anti-corrosive pigment. The anti-corrosive pigment is a pigment different from the conductive pigment. A particularly suitable composition is one in which the anti-corrosive pigment is selected from the group comprising zinc phosphates, aluminum triphosphates, zinc oxide, and silicates. Particularly good corrosion protection is achieved when the anti-corrosive pigment is a silicate, in particular a calcium-modified silicate, preferably with a particle size d (50) of 2.5 pm to 4.0 pm.

[0033] In order to achieve particularly effective corrosion protection, the corrosion protection pigment can be contained at 0.1 wt.% to 15.0 wt.%, in particular at 2.5 wt.% to 10.0 wt.%, preferably at 5.0 wt.% to 9.0 wt.%, based on the solids.

[0034] A composition containing bentonite, especially in a concentration of 0.25 wt.% to 1.5 wt.% based on the solids content, is particularly advantageous. This makes the composition particularly stable and durable, and the properties of the coating layer can be improved. Bentonite has the CAS number 1302-78-9.

[0035] A composition containing pyrogenic silicon dioxide, especially in a concentration of 0.25 wt.% to 1.5 wt.% based on the solids content, is particularly stable and durable. This can also improve the properties of the coating layer. Pyrogenic silicon dioxide has the CAS number 112945-52-5.

[0036] The binder can also improve the properties of the composition and the coating layer. A binder containing phenolic resin, epoxy resin, polyester resin, and polyurethane is particularly suitable. A composition has proven particularly suitable in which the phenolic resin is present in a concentration of 2.0 wt.% to 15.0 wt.%, in particular 4.0 wt.% to 10.0 wt.%, preferably 6.0 wt.% to 8.0 wt.%, based on the solids content.

[0037] The phenolic resin may be contained in amounts of 30 wt.% and 40 wt.%, in particular in amounts of 35 wt.% to 37.5 wt.%, based on the binder.

[0038] A composition is also particularly suitable in which the epoxy resin is contained at 1.0 wt.% to 10.0 wt.%, in particular at 2.5 wt.% to 7.5 wt.%, preferably at 4.0 wt.% to 6.0 wt.%, based on the solids.

[0039] The epoxy resin may also be present in an amount of 25% to 35% by weight, in particular 30% to 33% by weight, based on the binder.

[0040] Furthermore, the epoxy resin can be a polyether based on bisphenols, in particular bisphenol A, and epichlorohydrin.

[0041] A composition in which the epoxy resin is a phenoxy resin has proven particularly suitable. A phenoxy resin with a molecular weight of 52,000 to 60,000 Daltons is preferred, and preferably with a molecular weight of 52,000 to 55,000 Daltons is preferred. The molecular weight is determined according to DIN EN ISO 16014-5:2012.

[0042] A composition containing the polyester resin in a concentration of 0.1 wt.% to 5.0 wt.%, in particular 0.3 wt.% to 3.0 wt.%, preferably 0.5 wt.% to 2.0 wt.%, based on the solids content, has also proven particularly suitable. The polyester resin can advantageously increase elasticity during forming and thus improve the fracture pattern when bonding the coating. Furthermore, abrasion on the forming tools can be reduced, thus advantageously increasing the service life of the tools.

[0043] The polyester resin may advantageously be present in an amount of 0.1 wt.% to 20.0 wt.%, in particular 0.5 wt.% to 10.0 wt.%, preferably 5.0 wt.%, based on the binder.

[0044] It is preferred that the polyester resin has a molecular weight of 5,000 to 25,000 Daltons, especially 7,000 Daltons. Here, too, the molecular weight can be determined according to DIN EN ISO 16014-5:2012. A composition in which the polyisocyanate is an aliphatic polyisocyanate has also proven particularly preferred.

[0045] It has also proven particularly preferred if the polyisocyanate is present at 2.5 wt.% to 6.5 wt.%, preferably at 3.5 wt.% to 5.5 wt.%, based on the solids.

[0046] The polyisocyanate may advantageously be present in an amount of 20.0 wt.% to 30.0 wt.%, in particular 25.0 wt.% to 28.0 wt.%, preferably 27.5 wt.%, based on the binder.

[0047] Furthermore, a blocked polyisocyanate, in particular with a deblocking temperature of > 140 °C, may be present. It is preferred if the blocked polyisocyanate has an isocyanate content of 4.5% to 12%, in particular 8.0% to 9.0%, based on the total mass of the polyisocyanate.

[0048] The composition may also contain an unblocked polyisocyanate. In this case, it is particularly preferred if the unblocked polyisocyanate has an isocyanate content of 15% to 25% based on the polyisocyanate.

[0049] It has proven particularly suitable if the composition contains a blocked and an unblocked polyisocyanate.

[0050] A composition in which the binder forming the polymer matrix consists exclusively of a phenolic resin, an epoxy resin, a polyester resin, and a polyisocyanate has proven particularly suitable. It is particularly preferred if the components exhibit the properties mentioned above. It is therefore particularly preferred that the epoxy resin is a phenoxy resin. Furthermore, the polyisocyanate is preferably an aliphatic polyisocyanate. In this way, a particularly flame-resistant and, at the same time, readily formable, adhesive coating layer can be provided.

[0051] It has been shown that the composition and the lacquer layer have particularly advantageous properties when the ratio in wt. % of the binder to the pigments is 1.0:2.0 to 1.0:6.0, in particular 1.0:4.0 to 1.0:6.0, preferably 1.0:4.0 to 1.0:5.0, even more preferably 1.0:4.0 to 1.0:4.6. In order to improve the properties of the composition and the lacquer layer, the composition can contain a wetting agent, in particular a block copolymer with pigment-affinic groups, preferably a low-molecular-weight unsaturated polycarboxylic acid polymer. If a wetting agent is included, it is particularly preferred if the wetting agent is included at 0.1 wt.% to 2.0 wt.%, in particular 0.1 wt.% to 1.0 wt.%, preferably 0.1 wt.% to 0.25 wt.%, based on the solids.

[0052] The wetting agent may also be present in a concentration of 0.01 wt.% to 1.0 wt.%, in particular 0.1 wt.% to 0.8 wt.%, based on the pigments. Likewise, the wetting agent may be present in a concentration of 1.0 wt.% to 4.0 wt.%, in particular 2.5 wt.% to 3.7 wt.%, based on the binder.

[0053] In order to improve the properties of the composition and the paint film, a defoamer may be included, in particular foam-destroying polymers, preferably foam-destroying polyacrylates.

[0054] If a defoamer is present in the composition, it is particularly preferred if the defoamer is present at 0.01 wt.% to 2.0 wt.%, in particular 0.1 wt.% to 1.0 wt.%, preferably 0.1 wt.% to 0.25 wt.%, based on the solids.

[0055] A strong, easily formable, particularly flame-retardant or non-flammable, corrosion-resistant and easily weldable paint layer is obtained by a composition comprising a phenolic resin with 2 to 15 wt.%, an epoxy resin with 1 to 10 wt.%, a polyester resin with 0.1 to 5 wt.%, a polyisocyanate with 1 to 10 wt.%, a conductive pigment with 50 to 90 wt.%, and a corrosion protection pigment with 0.1 to 15 wt.%, based on the solids.

[0056] In particular, further components may be included, for example wetting agents, in particular with 0.1 to 2.0 wt.% based on the solids and / or defoamers, in particular with 0.05 to 1.5 wt.% based on the solids.

[0057] It has proven particularly suitable if the components mentioned have the properties mentioned above.

[0058] The composition is particularly stable and easy to process if the solids content is 20 wt.% to 95 wt.%, in particular 30 wt.% to 85 wt.%, preferably 40 wt.% to 75 wt.%, based on the total composition, i.e. including solvent.

[0059] The composition is particularly easy to process and durable when the solvent is selected from the group of esters, especially methoxypropyl acetate and / or butyl diglycol acetate, ketones, especially cyclohexanone, aromatic hydrocarbons, especially solvent naphtha, and mixtures thereof. This also simplifies the processing of the composition and allows for a short drying time.

[0060] A composition has proven particularly suitable wherein the solvent is a butyldigylcol acetate, methoxypropyl acetate or a mixture of methoxypropyl acetate and butyldigylcol acetate.

[0061] Furthermore, a composition is particularly advantageous in which the solvent is present in an amount of 15% to 70% by weight, preferably 25% to 60% by weight, more preferably 30% by weight, based on the total composition.

[0062] The composition is particularly durable and stable when produced in a process comprising the following steps: a) mixing the phenolic resin with a portion of the solvent, in particular with the addition of additives, b) adding the anti-corrosive pigment, and preferably wet grinding the mixture, in particular to a fineness of 1 pm up to 10 pm, d) adding the conductive pigment and the remaining binder, the epoxy resin, the polyester resin and the polyisocyanate, with stirring e) adding the remaining portions of the solvent f) in particular filtering the composition.

[0063] The fineness of the wet grinding is determined in the Hergmann grindometer according to DIN 53203.

[0064] In particular, the aforementioned components, wetting agents and / or defoamers and / or fumed silica, can be added as additives. The composition has a wide range of applications, including the use of the composition for coating metal sheets by coil coating, spraying, or dipping. The composition can also be used for coating metal objects by spraying or dipping.

[0065] Particularly suitable metal surfaces for coating with the stated composition are aluminum, aluminum alloy systems or steel, in particular electrolytically galvanized steel, hot-dip galvanized steel, zinc / magnesium galvanized steel, zinc / aluminum galvanized steel, zinc / iron galvanized steel or ungalvanized steel.

[0066] A particularly quick and simple method for coating a metal surface is characterized by coating a metal surface with a previously described composition, and baking the composition at temperatures of 140 °C to 260 °C (peak metal temperature), with the baking time preferably being 15 seconds to 60 seconds. The peak metal temperature can be determined using temperature measuring strips. It can also be determined using an infrared thermometer.

[0067] The adhesion of the paint layer is particularly good when the metal surface is made of galvanized, alloy-galvanized, or ungalvanized steel, or of aluminum or an aluminum alloy. Adhesion can be further improved if the metal surface is primed, particularly if it is chromium-free. A chemical conversion treatment that does not contain any substances prohibited by ELV Directive 2000 / 53 / EC or RoHS Directive 2011 / 65 / EU is particularly suitable as a primer.

[0068] The invention also relates to a metal sheet or a metal article obtainable by a method described above.

[0069] According to the invention, a metal sheet or a metal object, in particular a battery box, with a coating comprising an isocyanate-crosslinked, thermosetting matrix comprising a phenolic resin, a polyester resin, an epoxy resin, in particular a phenoxy resin, as well as a conductive pigment distributed in the thermosetting matrix and a corrosion protection pigment distributed in the thermosetting matrix is ​​further provided.

[0070] The components of the coating can, in particular, have the properties previously mentioned with reference to the composition. Furthermore, the components of the composition previously mentioned as optional can preferably also be present in the coating. A particularly suitable embodiment therefore relates to a metal sheet or a metal object with a coating that additionally comprises a wetting agent and / or a defoamer and / or pyrogenic silicon dioxide, preferably with the specific properties previously mentioned. Such a coating is particularly suitable for battery boxes.

[0071] Particularly good corrosion protection, good formability, and good weldability have been achieved for a metal sheet or metal object with a coating thickness of 2 μm to 20 μm, particularly 4 μm to 10 μm, and preferably 6 μm to 8 μm. If the dry film has a thickness of up to 8 μm, the coating layer is highly weldable. It has also been shown that very good corrosion protection can also be achieved on surfaces with a layer thickness of 6 μm or more.

[0072] A further aspect of the invention relates to a battery box, in particular for the battery of an electric vehicle, comprising at least one coated metal surface, in particular facing the environment, i.e. facing away from the battery, wherein the coating is produced by a method described above.

[0073] In addition, a battery box, in particular for the battery of an electric vehicle, comprising a coated metal surface, in particular facing the environment of the battery box, is also according to the invention, wherein the coating comprises: a, in particular isocyanate-crosslinked, thermosetting matrix comprising a phenolic resin, an epoxy resin, and in particular a polyester resin, and a conductive pigment distributed in the thermosetting matrix, and in particular a corrosion protection pigment distributed in the thermosetting matrix.

[0074] It is particularly advantageous if the components have the properties described above, for example if the epoxy resin is a phenoxy resin.

[0075] The coating may additionally comprise one of the optional components of the composition listed above.

[0076] The battery case then comprises a coating based on the composition described above, in particular obtainable by drying or curing from the composition described above. Advantageous embodiments of the invention are illustrated, without limiting the general inventive concept, by the following examples: Table 1: Recipes for exemplary compositions and comparative recipes The components of the binder are given in such a way that the amounts refer to 100% by weight of the binder. The amount of binder in the solids is given in the last line as the upper value and the amount of pigments in the solids is given as the lower value. The values ​​indicate how many parts binder and how many parts pigments are contained. The total indicates the total number of parts. For example, a binder:pigment ratio of 1.0:4.0 means that a total of 5 parts are present, consisting of 1 part binder and 4 parts pigments. Therefore, for 70% by weight solids, there are 14 parts binder and 56 parts pigments. The binder therefore accounts for 20% by weight of the solids. The amount of additives is not taken into account.

[0077] Comparative examples V1 -V6 contained zinc pigment in a proportion of less than 50 wt.% based on the solids and formulations V1 and V4 did not contain any polyester resin.

[0078] Compositions V1-V15 were prepared by first dispersing the phenolic resin, solvent, defoamer, and wetting agent individually in a dissolver with gentle stirring, followed by homogenization of the mixture. The anti-corrosive pigment and, if required, the fumed silica were then added. Subsequently, wet grinding was performed using a bead mill (CeOs rod with ZrOs beads, 0.80-1.00 mm), grinding the mixture to a fineness of <10 pm (grindometer according to Hergmann, DIN 53203).

[0079] In a second phase, the remaining components—the conductive pigment, the other binder components, and the remaining solvent—were slowly added with gentle stirring and homogenized in a dissolver. The desired viscosity can be adjusted with the solvent. The homogenized mixture was poured into a drum and filtered with a mesh size of < 80 pm (PES 80 / 32, 80 pm / 32% open sieve area).

[0080] For further testing, metal sheets were coated with one of the compositions V1 to V15, and the coatings were baked. A baking time of 30 seconds was used at a circulating air temperature of 420°C with a fan speed of 2000 rpm, as this corresponds to a desired peak metal temperature of over 240°C at a belt speed of 100 to 120 meters / second. The tests were then conducted and evaluated. The results are summarized in Table 2. To assess the properties of each composition, they were compared with the most common reference on the market, namely Granocoat® ZE from Henkel with a layer thickness of 6 μm.

[0081] A composition described in EP 1 030 894 could also be used as a reference.

[0082] If the property of the respective composition showed similar or slightly better results than the reference at the same layer thickness, the value "o" was assigned. For significantly better results in the respective property, the value "+" was assigned, and for outstandingly better results, the value

[0083] Table 2: Schematic representation of the properties of the dry film

[0084] As shown in Table 2, the coatings produced from the comparative formulations V-1 to V-6 showed no improvement in flammability and weldability compared to the reference coatings. In contrast, the coatings obtained from the compositions V7 to V15 showed good weldability even with 50 Hz processes. In this study, a coating layer with a thickness of 8 μm was used in each case.

[0085] All coatings provided very good corrosion protection. The coatings are therefore suitable as replacements for cathodic electrocoating (KTL). This was tested both in the salt spray test (NSS DIN EN ISO 9227) and in the cyclic corrosion test (DIN ISO 11997-3, DIN 55635, and VDA 233-102). Furthermore, favorable fire behavior was demonstrated. This was tested using a simulated "thermal runaway" of battery cells inside a battery box. The temperature of 950°C, assumed according to the Chinese standard GB 38031 -2020, was simulated by an oxyacetylene flame on the back of the coated sheet. The coating did not ignite even at bright yellow heat > 1100°C. A sheet heated with a commercially available KT coating burned with an open, sooty flame. The coatings obtained from compositions V7 to V14 did not ignite even at bright yellow heat >1 100°C.Even the reference coating with Granocoat® ZE ignited under these test conditions.

[0086] It was shown that the coatings obtained from compositions V7-V15 exhibited very good adhesion and were generally easy to process further, as they were easily formable in the deep-drawing process with or without additional oiling, and were screwable, bondable, phosphatable, and cathodic dip-coatable. Furthermore, they were particularly suitable for phosphating.

[0087] It was found that all exemplary coatings provided good corrosion protection, with the coatings with compositions V7 to V11 demonstrating significant advantages over the reference. Furthermore, all exemplary coatings demonstrated high flexibility, as they were easily formable in the deep-drawing process; here, too, the coatings with compositions V7 to V11 proved particularly suitable. All exemplary coatings exhibited significantly better weldability than the reference examples. Furthermore, all exemplary coatings were superior to the reference composition in terms of flame retardancy.

[0088] The coatings obtained from compositions V7 to V15 are therefore very well suited for coating battery boxes and can also be used in other applications requiring high protection against corrosion, mechanical and thermal stress.

Claims

Patent claims 1. Composition for coating metal surfaces comprising a) a binder comprising - a phenolic resin with 2 to 15 wt.%, - an epoxy resin with 1 to 10 wt.%, - a polyester resin with 0.1 to 5 wt.%, - a polyisocyanate with 1 to 10 wt.%, b) at least one conductive pigment with 50 to 90 wt.%, and - a corrosion protection pigment with 0.1 to 15 wt.%, where all weight percentages are based on the solids and c) a solvent of 5 - 80 wt.% based on the total composition.

2. Composition according to claim 1, wherein the conductive pigment is present at 50.0 wt.% to 90.0 wt.%, in particular at 60.0 wt.% to 85.0 wt.%, preferably at 70.0 wt.% to 80.0 wt.%, based on the solids.

3. Composition according to claim 1 or 2, wherein at least one anti-corrosive pigment is included, wherein the anti-corrosive pigment is selected from the group comprising zinc phosphates, aluminum triphosphates, zinc oxide and silicates.

4. Composition according to one of claims 1 to 3, wherein the phenolic resin is present at 2.0 wt.% to 15.0 wt.%, in particular at 4.0 wt.% to 10.0 wt.%, preferably at 6.0 wt.% to 8.0 wt.%, based on the solids.

5. Composition according to one of claims 1 to 4, wherein the epoxy resin is present at 1.0 wt.% to 10.0 wt.%, in particular at 2.5 wt.% to 7.5 wt.%, preferably at 4.0 wt.% to 6.0 wt.%, based on the solids.

6. Composition according to one of claims 1 to 5, wherein the epoxy resin is a phenoxy resin, in particular with a molecular weight of 52,000 to 60,000 Daltons, preferably with a molecular weight of 52,000 to 55,000 Daltons.

7. Composition according to one of claims 1 to 6, wherein the polyester resin is present at 0.1 wt.% to 5.0 wt.%, in particular at 0.3 wt.% to 3.0 wt.%, preferably at 0.5 wt.% to 2.0 wt.%, based on the solids.

8. Composition according to one of claims 1 to 7, wherein the polyisocyanate is an aliphatic polyisocyanate and / or wherein the polyisocyanate is present at 2.5 wt.% to 6.5 wt.%, preferably at 3.5 wt.% to 5.5 wt.%, based on the solids.

9. Composition according to one of claims 1 to 9, wherein the ratio in wt.% of the binder to the pigments is 1.0:2.0 to 1.0:6.0, in particular 1.0:4.0 to 1.0:6.0, preferably 1.0:4.0 to 1.0:5.0, even more preferably 1.0:4.0 to 1.0:4.

6.

10. Composition according to one of claims 1 to 9, wherein the solvent is selected from the group of esters, in particular methoxypropyl acetate and / or butyl diglycol acetate, ketones, in particular cyclohexanone, aromatic hydrocarbons, in particular solvent naphtha, and mixtures thereof. 11 . Method for coating a metal surface, characterized in that - a metal surface is coated with a composition according to any one of claims 1 to 11, thereafter - the composition is baked at temperatures of 140 °C to 260 °C peak metal temperature, with a baking time of in particular 15 seconds to 60 seconds and then - the metal surface is formed into a component.

12. Metal sheet or metal article with a coating produced by a process according to claim 12 13 Metal sheet or metal article with a coating comprising - a thermosetting matrix, in particular an isocyanate-crosslinked one, comprising - a phenolic resin, - an epoxy resin, in particular a phenoxy resin, - a polyester resin, and - a conductive pigment distributed in the thermosetting matrix and - a corrosion protection pigment distributed in the thermosetting matrix.

14. Metal sheet or metal object according to claim 13, wherein the coating has a layer thickness of 2 pm to 20 pm, in particular from 4 pm to 10 pm, preferably from 6 pm to 8 pm.

15. Battery box, in particular for the battery of an electric vehicle, comprising a coated metal surface, in particular facing the surroundings of the battery box, wherein the coating is produced by a method according to claim 12, and / or wherein the coating comprises: - a thermosetting matrix, in particular cross-linked by isocyanates, comprising a phenolic resin, an epoxy resin, wherein the epoxy resin is in particular a phenoxy resin, and a Polyester resin, as well as - a conductive pigment distributed in the thermosetting matrix and - a corrosion protection pigment distributed in the thermosetting matrix.

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