Coating compositions comprising alkali metal salts of graphene oxide and coatings prepared from said coating compositions.

Abstract

This invention relates to a coating composition comprising at least one graphene oxide (GO-M) containing at least one monovalent metal ion selected from lithium, potassium, and mixtures thereof, at least one base material B and / or a silane compound SC, and at least one solvent S1. Furthermore, this invention relates to a method for preparing the coating composition of the present invention, a method for preparing at least one coating on a substrate using the coating composition of the present invention, and the coating or multilayer coating obtained by said method. Finally, this invention relates to the use of graphene oxide containing at least one monovalent metal ion selected from lithium, potassium, and mixtures thereof in a coating composition to improve the corrosion resistance of said coating composition.

Description

[0001] This invention relates to a coating composition comprising at least one graphene oxide (GO-M) containing at least one monovalent metal ion selected from lithium, potassium, and mixtures thereof, at least one base material B and / or a silane compound SC, and at least one solvent S1. Furthermore, this invention relates to a method for preparing the coating composition of the present invention, a method for preparing at least one coating on a substrate using the coating composition of the present invention, and a coating or multilayer coating obtained by said method. Finally, this invention relates to the use of graphene oxide containing at least one monovalent metal ion selected from lithium, potassium, and mixtures thereof in a coating composition to improve the corrosion resistance of said coating composition. Existing technology

[0002] Corrosion of metallic materials remains a problem that has yet to be satisfactorily solved. Corrosion is the electrochemical reaction between a metallic material and its atmospheric environment (especially oxygen and water), leading to significant changes and damage to the material. This damage results in impaired functionality of metallic components, necessitating repair or replacement. Therefore, corrosion and consequently, the economic implications of corrosion prevention are highly relevant.

[0003] For these reasons, corrosion control is highly valued in almost all sectors of the metal industry (e.g., mechanical engineering and equipment, automotive industry (vehicle manufacturing), aerospace industry, shipbuilding industry, electrical industry, precision machinery industry, construction industry, and home appliances / “white goods”), but especially in the automotive and aerospace industries. Particularly in the latter, metallic substrates are widely used for components exposed to atmospheric conditions (and in some cases, extreme atmospheric conditions).

[0004] In the automotive and aerospace industries, metal substrates typically undergo costly multi-layer coating processes. This is necessary to meet the requirements of vehicle manufacturing and the aerospace industry—for example, effective corrosion control.

[0005] Typically, a conversion coating is first applied to a metal substrate to protect it from corrosion and improve adhesion to the overcoat. Examples include phosphating of steel substrates or chromate treatment of aluminum substrates or aluminum alloys, such as 2000-7000 series aluminum alloys like AA2024, AA5083, AA6111, AA6014, AA6061, and AA7075. The latter is primarily used in the aerospace industry due to its excellent processability, low density, and resistance to physical stress. However, this material also exhibits a detrimental tendency for filamentous corrosion, which typically occurs after physical damage to the substrate coating, coupled with high atmospheric humidity. Corrosion then propagates beneath the substrate coating in a filamentary manner, causing filamentous corrosion damage to the metal substrate. Therefore, effective corrosion control is crucial.

[0006] Following pretreatment and appropriate conversion coating application, a primer layer is typically applied to further protect against corrosion. This primer layer is based on an organic polymer matrix and may further contain anti-corrosion pigments, as described later. In the automotive industry, this primer layer is typically an electrodeposited coating, more particularly a cathodic electrophoretic coating, also known as an ED coating. In the aircraft industry, specialty epoxy resin base coats are commonly used. In automotive finishing, two primer coats are typically applied to compensate for any remaining unevenness on the substrate surface and to protect the cathodic electrophoretic coating from stone chip damage. In the final step, a topcoat is applied, consisting of two separately applied coats: a base coat and a clear coat.

[0007] One effective form of corrosion protection for metal substrates still in use today is the use of chromate compounds. For example, chromate compounds are included in conversion coatings as part of a surface pretreatment of the metal substrate (also known as chromate treatment). Similarly, chromate compounds in chromate form (e.g., barium chromate, zinc chromate, strontium chromate) are typically used as anti-corrosion pigments in anti-corrosion coating compositions (preferably primers, first and second coats of mixed primers, or fillers) based on organic polymer resins.

[0008] The corrosion protection effect of chromate compounds in the conversion coating is achieved by eroding the metal surface (e.g., aluminum) and simultaneously reducing chromate compounds to trivalent chromium in proportion, while the low-solubility passivation coating contains aluminum(III) / chromium(III) and chromium(VI) oxide hydrates to achieve the corrosion protection effect.

[0009] However, the problem is related to the high toxicity and carcinogenicity of chromate compounds. Therefore, avoiding chromate compounds in the automotive, household, and aerospace industries, while maintaining proper corrosion protection, is a long-term requirement in these industrial sectors.

[0010] An example of a possible method to avoid chromate compounds while maintaining adequate corrosion protection is the use of oxoanions (and / or salts) of various transition metals, such as MoO4. 2- MnO4 - and VO3 - Lanthanide cations or various organic substances, such as benzotriazoles, ethylenediaminetetraacetic acid (EDTA), quinoline derivatives, or phosphate derivatives, are also known to be used. The underlying mechanisms of action are complex and are not yet fully understood. They range from forming a passivating oxide / hydroxide coating on corroded metal surfaces to the complexation of certain metal cations (e.g., Cu(II)) to inhibit specific forms of corrosion (e.g., filamentary corrosion of aluminum-copper alloys).

[0011] Another approach involves using so-called nanocontainer materials and / or layered materials, such as organic cyclodextrins or inorganic materials like zeolites, alumina nanotubes, and chlorophyll. Hydrotalcite components and layered double hydroxide materials have also been used. The latter are typically referred to in general technical literature with the corresponding abbreviation "LDH." In the literature, they are usually represented by the idealized general formula [M2] 2+ (1-x) M3 3+ x(OH)2] x+ [A y [-(x / y)nH₂O] or similar empirical formulas. In these formulas, M₂ represents a divalent metal cation, M₃ represents a trivalent metal cation, and A represents an x-valent anion. In the case of naturally occurring LDH, these anions are typically inorganic anions such as carbonate, chloride, nitrate, hydroxide, and / or bromide ions. Various other organic and inorganic anions may also be present in synthetic LDH. The above general formulas also consider water of crystallization. In the case of hydrotalcite, the divalent cation is Mg. 2+ The trivalent cation is Al 3+ The anion is carbonate, although the latter can be replaced at least proportionally by hydroxide ions or other organic and inorganic anions. Hydrotalcite and LDH have a layered structure similar to brucite (Mg(OH)₂), where, due to the presence of positively charged trivalent metal cations, there exists a negatively charged layer of intercalating anions, which typically also contain water of crystallization, between each pair of positively charged metal hydroxide layers. In the above formula, the LDH layer structure is indicated by the correspondingly placed brackets. Various reagents, such as the preservatives mentioned above, can be inserted between two adjacent metal hydroxide layers through non-covalent, ionic, and / or polar interactions.

[0012] The previously described nanocontainer materials and / or LDH materials can be directly incorporated into corresponding polymer-based coatings, such as conversion coatings and / or primers. Experiments are also underway to completely replace the conversion coating, in which case the corresponding primer is then applied directly to the metal. In this way, the coating process becomes less complex and therefore more cost-effective.

[0013] In recent years, due to graphene's excellent chemical resistance, mechanical strength, and impermeability to gases and corrosive ions, research has focused on introducing graphene (a single atom or several layers of crystalline graphite sheets) or graphene oxides into anti-corrosion coatings. Compared to graphene, graphene oxides have more oxygen-containing organic functional groups on their surface, which increases compatibility and bonding surface structure with certain organic resins (such as epoxy resins). However, introducing graphene oxides into organic coatings cannot fully meet the anti-corrosion requirements of the automotive, aerospace, household, and construction industries.

[0014] Therefore, it is advantageous for the coating composition to possess excellent anti-corrosion properties without using toxic compounds, such as chromium and other heavy metal compounds, as well as fluorinated and phosphorus-containing compounds. The coating composition should exhibit excellent storage stability and be suitable for commonly used application equipment. Furthermore, the composition should have excellent adhesion to metal substrates and any underlying and / or upper coating layers, allowing it to be applied directly to metals without prior use of a conversion layer, and to apply other coatings to prepare multilayer coatings.

[0015] Purpose

[0016] Therefore, the object of the present invention is to provide a coating composition with excellent anti-corrosion properties without the use of toxic compounds (e.g., chromium and other heavy metal compounds, fluorine compounds, and phosphate-containing compounds). The coating composition should have excellent storage stability and should be suitable for commonly used application equipment. Furthermore, the coating composition should have a long pot life and high adhesion to the substrate and any undercoat and / or overcoat. Therefore, the coating composition should also allow for overcoating with common coating compositions, such as fillers, basecoats, and / or topcoat compositions, without any problems. In addition, the coating composition should result in a coating with sufficient flexibility to allow deformation of the coating substrate without cracking in the coating obtained by the coating composition of the present invention.

[0017] Technical solutions

[0018] The above objective is achieved by the subject matter claimed in the claims and the preferred embodiments of that subject matter described below.

[0019] Therefore, the first subject of the present invention is a coating composition comprising:

[0020] a) At least one graphene oxide (GO-M) containing at least one monovalent metal ion selected from lithium, potassium and mixtures thereof;

[0021] b) at least one base material b and / or at least one silane compound SC; and

[0022] c) At least one solvent S1.

[0023] The above-described coating composition is also referred to hereinafter as the coating composition of the present invention, and is therefore the subject of the present invention. Preferred embodiments of the coating composition of the present invention are described below and in the dependent claims.

[0024] Given the prior art, it is surprising and unexpected to those skilled in the art that the objectives upon which this invention is based can be achieved by using graphene oxides containing lithium and / or potassium ions (hereinafter referred to as graphene oxide salts). Introducing said graphene oxide salts into liquid coating compositions containing at least one base material (i.e., an organic coating composition) and / or at least one silane compound (hereinafter also referred to as a conversion coating) results in significantly improved corrosion resistance compared to coating compositions containing graphene oxides or those containing only a binder and / or a silane compound. Despite the presence of graphene oxide salts, the coating compositions of this invention exhibit excellent storage stability, a long pot life, and can be applied using common application devices (e.g., pneumatic or electrostatic spray guns, roller coating, or roll coating). Furthermore, the coating compositions of this invention exhibit excellent adhesion to substrates, thus allowing direct application to the substrate without the need for a pre-application of a conversion coating. In addition, the coating compositions of this invention also exhibit excellent adhesion to further undercoats and / or topcoats, making them highly suitable for methods of preparing multilayer coating systems as primers, first and second coat primers, or fillers. Furthermore, the flexibility of the coating obtained by the coating composition of the present invention is not negatively affected by the addition of graphene oxide salt, thus reducing the formation of cracks in the coating prepared by the coating composition of the present invention when the coated substrate is bent.

[0025] Another subject of the present invention is a method for preparing the coating composition of the present invention, comprising the following steps:

[0026] (a) Preparing a dispersion D of at least one graphene oxide (GO-M) containing at least one monovalent metal ion selected from lithium, potassium, and mixtures thereof in at least one solvent S2; and

[0027] (b) Add the dispersion D prepared in step (a) to a mixture comprising at least one base material B and / or at least one silane compound SC and at least one solvent S1.

[0028] Another subject of the present invention is a method for forming at least one coating on a substrate (S), comprising the steps of:

[0029] (i) Applying the coating composition of the present invention or the coating composition prepared by the method of the present invention directly onto the substrate (S);

[0030] (ii) A film is formed from the coating composition applied in step (i) by curing the coating composition; and

[0031] (iii) Optionally, at least one other coating composition is applied to the coating formed in step (ii) and the coating composition is cured.

[0032] Another subject of the present invention is a coating or multilayer coating (MC) prepared by the method of the present invention.

[0033] The final subject of this invention is the use of at least one graphene oxide containing at least one monovalent metal ion selected from lithium, potassium, and mixtures thereof in a coating composition to improve the corrosion resistance of said coating composition.

[0034] Detailed description

[0035] In the context of this invention, the measurement methods used to determine certain characteristic variables are described in the Embodiments section. Unless otherwise explicitly stated, these measurement methods should be used to determine the corresponding characteristic variables. If an official standard is referenced in the context of this invention without any indication of an official expiry date, the reference implicitly refers to the version of the standard valid as of the application date, or, if no valid version was available at that time, the last valid version.

[0036] The term "graphene oxide" generally refers to graphene oxide having the following general structure (A):

[0037]

[0038] Therefore, a graphene oxide containing at least one monovalent metal ion refers to a graphene oxide in which at least one carboxylic acid group is converted into at least one carboxylic acid group having at least one monovalent metal counterion.

[0039] All film thicknesses reported in the context of this invention should be understood as dry film thicknesses. Therefore, in each case, it refers to the thickness of the cured film. Thus, when a coating is reported to be applied with a specific film thickness, this means that the coating is applied in a manner that produces said film thickness after curing.

[0040] The coating composition of the present invention:

[0041] The coating composition of the present invention comprises at least one graphene oxide (GO-M) containing at least one monovalent metal ion selected from lithium, potassium, and mixtures thereof, at least one base material B and / or at least one silane compound SC, and at least one solvent S1. Therefore, the coating composition of the present invention is preferably a liquid coating composition at 23°C.

[0042] Graphene oxides containing at least one monovalent lithium and / or potassium ion:

[0043] Various methods have been described in the prior art for the preparation of graphene and graphene oxides. These can be broadly categorized into two types: "top-down" and "bottom-up" methods. In the first type, graphite, as the starting material, is mechanically, electrochemically, or thermally exfoliated and oxidized to obtain graphene oxides. The most commonly used "top-down" techniques are the Hummers method and modified Hummers methods, which use strong oxidizing agents such as sulfuric acid, sodium nitrate, or potassium permanganate, along with catalysts. The other type of "top-down" technique is the electrochemical method, where exfoliation is achieved by applying an electric current, thereby allowing different types of ions from the electrolyte used to insert into the graphite layers.

[0044] The graphene oxide (GO-M) contained in the coating composition of the present invention, comprising at least one monovalent metal ion selected from lithium, potassium, and mixtures thereof, is preferably obtained by adding a corresponding metal salt solution to the graphene oxide, ultrasonic treatment, filtration, and drying of the residue. The graphene oxide is also preferably prepared by a two-step electrochemical exfoliation method, wherein graphene rods are placed in a NaOH solution and an anodic current is applied using a dual-electrode system to achieve exfoliation. In a subsequent step, anionic electrolysis is performed in a sulfuric acid solution to obtain the graphene oxide.

[0045] The monovalent metal ion is selected from lithium, potassium, and mixtures thereof. Particularly preferred is lithium. The use of lithium-ion-containing graphene oxides (i.e., lithium-ion-functionalized graphene oxides) results in excellent corrosion resistance in organic coating compositions or conversion coating compositions.

[0046] Surprisingly, the excellent corrosion resistance of organic coating compositions and conversion coating compositions containing graphene oxide (GO-M) with at least one monovalent metal ion selected from lithium, potassium, and mixtures thereof, preferably graphene oxide containing lithium ions, has been achieved by introducing only a small amount of said graphene oxide (GO-M) into the composition. The coating composition preferably contains 0.1 ppm to 5% by weight, more preferably 0.5-2% by weight, even more preferably 0.1 ppm to 1% by weight, even more preferably 0.1-500 ppm, even more preferably 0.3-50 ppm, and very preferably 0.35-1 ppm of at least one graphene oxide (GO-M) containing at least one monovalent metal ion selected from lithium, potassium, and mixtures thereof, preferably graphene oxide containing at least one lithium ion, in each case based on the total weight of the coating composition.

[0047] base material B Silane compounds SC:

[0048] The waterborne coating composition of the present invention comprises at least one base material B and / or at least one silane compound SC as a second mandatory component (b).

[0049] Base material B:

[0050] In the context of this invention and according to DIN EN ISO 4618:2007-03, "base material" refers to the non-volatile component of a coating composition, excluding pigments and fillers. However, in the following text, this expression is primarily used for specific physically curable polymers, which may optionally also be thermocurable, such as polyurethanes, polyesters, polyacrylates, and / or copolymers of said polymers. Therefore, the term "base material" in the sense of this invention does not include curing agents or crosslinking agents used to crosslink the base material to form a film. In the context of this invention, a copolymer refers to polymer particles formed from different polymers. This explicitly includes polymers covalently bonded to each other and polymers in which different polymers are bonded to each other by adhesion. This definition also covers both types of bonding.

[0051] In the context of this invention, the term "physical curing" means the formation of a film by evaporating a solvent from a polymer solution or polymer dispersion. Typically, this curing does not require a crosslinking agent.

[0052] In the context of this invention, the term "thermosetting" refers to thermally initiated crosslinking of a coating film, wherein a self-crosslinking base material or a separate crosslinking agent plus base material (external crosslinking) is used. The crosslinking agent contains reactive groups complementary to the reactive functional groups present in the base material, thereby forming a macro-crosslinked coating film when the base material and the crosslinking agent react.

[0053] The base component present in the coating composition of the present invention always exhibits at least a certain proportion of physical curing. Therefore, if the coating composition contains a heat-curable base component, this does not preclude the possibility that curing also includes a certain proportion of physical curing.

[0054] The selection and combination of suitable base material B are based on the desired and / or required performance of the coating system to be prepared. Another criterion for selection is the desired and / or required curing conditions, more particularly the curing temperature. Those skilled in the art are familiar with how to make this selection and can make adjustments accordingly. In the case of a water-based coating composition of the present invention, an ionic or nonionic stable polymer is used as base material B. Anionic stable polymers are known to be polymers modified with anionic groups and / or functional groups, which can be converted to anions (e.g., carboxyl groups and / or carboxylic acid groups) by a neutralizing agent to promote dissolution or dispersion in water. Nonionic stable polymers are polymers modified with polyoxyalkylene groups to increase their water solubility or water dispersibility. Suitable base material B is selected from the group consisting of: (i) poly(meth)acrylates, more particularly hydroxyl-functionalized and / or carboxylic acid-functionalized and / or amine-functionalized poly(meth)acrylates, (ii) polyurethanes, more particularly hydroxyl-functionalized and / or carboxylic acid-functionalized and / or amine-functionalized polyurethanes, (iii) linear or branched polyesters or polyamide-modified polyesters, more particularly linear or branched polyester polyols, (iv) polyethers, more particularly polyether polyols, (v) polyepoxides, (vi) phenoxy resins, (vii) copolymers of the polymers, and (vi) mixtures thereof; preferably polyepoxides, linear or branched polyesters and / or polyether polyurethane copolymers.

[0055] Suitable hydroxyl-functionalized polymers and / or resins have hydroxyl values ​​of 30-400 mg KOH / g solids, more preferably 100-300 KOH / g solids, determined according to DIN 53240-2:2007-11. In the case of pure poly(meth)acrylates, the OH value can also be determined with sufficient accuracy by calculation based on the OH-functionalized monomers used. The acid value can be 0-30 mg KOH / g solids, determined according to DIN EN ISO 2114:2006-11.

[0056] The glass transition temperature of the hydroxyl-functionalized polymers and / or resins is preferably -150 to 100°C, more preferably -120°C to 80°C, as determined by DSC according to DIN EN ISO 11357-2:2014-07.

[0057] Suitable polyester polyols are described, for example, in EP-A-0 994 117 and EP-A-1 273 640. In one or more embodiments, the polyurethane polyol is prepared by reacting a polyester polyol prepolymer with a suitable diisocyanate or polyisocyanate, as described, for example, in EP-A-1 273 640. Suitable polysiloxane polyols are described, for example, in WO-A-01 / 09260, wherein the polysiloxane polyol may preferably be used in combination with other polyols, more particularly with those having a higher glass transition temperature.

[0058] Suitable poly(meth)acrylate polyols have a mass-average molecular weight (Mw) of 1000-20000 g / mol, more particularly 1500-10000 g / mol, measured in each case by gel permeation chromatography (GPC) relative to a polystyrene standard.

[0059] The poly(meth)acrylate polyol preferably comprises at least one hydroxyl-functionalized monomer and optionally other monomers, such as alkyl (meth)acrylates and / or vinyl aromatic monomers and / or acid-functionalized unsaturated monomers. Suitable hydroxyl-functionalized monomers are hydroxyalkyl (meth)acrylates, such more particularly 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and mixtures thereof. Suitable alkyl methacrylates include, for example, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, pentyl methacrylate, hexyl methacrylate, ethylhexyl methacrylate, 3,3,5-trimethylhexyl methacrylate, stearyl methacrylate, or lauryl methacrylate; cycloalkyl methacrylates include, for example, cyclopentyl methacrylate, isobornyl methacrylate, or cyclohexyl methacrylate and mixtures thereof. Suitable vinyl aromatic monomers include, for example, vinyltoluene, α-methylstyrene, or particularly styrene, amides or nitriles of acrylic acid or methacrylic acid, vinyl esters, or vinyl ethers. Suitable acid-functionalized unsaturated monomers include, for example, acrylic acid and / or methacrylic acid.

[0060] According to a first particularly preferred embodiment, the at least one base material B is selected from polyepoxides. In the context of this invention, a polyepoxide is a polymer containing, on average, at least one epoxy group per molecule. The polyepoxides that can be used according to the invention are preferably selected from the group consisting of: glycidyl ethers, such as bisphenol A diglycidyl ether, bisphenol F diglycidyl ester, epoxide-phenolic varnish resin, epoxide-o-cresol-phenolic varnish resin, 1,3-propane diglycidyl ether, 1,4-butane diglycidyl ether or 1,6-hexane diglycidyl ether and polyoxyethylene glycidyl ether; glycidyl esters, such as hexahydrophthalic acid diglycidyl ester; glycidylamines, such as diglycidyl aniline or tetraglycidylmethylene diphenylamine; alicyclic epoxides, such as 3,4-epoxycyclohexyl ethylene oxide or 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexane carboxylate; and glycidyl isocyanurate esters, such as triglycidyl isocyanurate. These compounds contain hydroxyl groups along the chain and epoxy groups at the ends. The ability of epoxy resins to crosslink via epoxy and hydroxyl groups varies depending on their chain length. The crosslinking ability of epoxy groups decreases with increasing chain length and molar mass, while the crosslinking ability of hydroxyl groups increases with increasing chain length. In the context of this invention, all epoxy resins known to those skilled in the art can ultimately be used, examples being commercially available epoxy resins described later below, which are obtained as solutions or dispersions in organic solvents or water. Particularly preferably, the at least one base material B has an epoxy equivalent (EEW) of 100-400 g / Eq., preferably 150-350 g / Eq., and very preferably 200-300 g / Eq., determined according to DIN EN ISO 3001:199-11.

[0061] When the at least one base material B is selected from polyepoxides, it is particularly preferred that the at least one base material B is selected from a mixture of two different polyepoxides, wherein the dynamic viscosity of the first polyepoxide B1 is 0.5 to 2 Pa*s (measured according to ASTM D 445-06), and the dynamic viscosity of the second polyepoxide B2 is 800-1400 mPa*s (measured according to DIN EN ISO 3219:1994-10 at a shear rate of 500 1 / s and 23°C). The combined use of the polyepoxide mixture with graphene oxide (GO-M) containing at least one monovalent metal ion selected from lithium, potassium, and mixtures thereof (preferably at least one lithium-ion functionalized graphene oxide) results in excellent corrosion resistance without negatively affecting high storage stability, pot life, adhesion to substrates, and interlayer adhesion.

[0062] These epoxy resins are available, for example, in the form of solutions or dispersions in organic solvents or water, under the trade name Beckopox by Cytec or under the trade name Epikote by Momentive.

[0063] According to a second particularly preferred embodiment, the at least one base material B is selected from linear and / or branched polyesters, preferably linear polyesters. Using a combination of linear and branched polyesters allows the flexibility of the coating composition to be adjusted by changing the ratio between the polyesters, thereby enabling the coating composition of the present invention to be adapted to the specific intended use of the coated substrate.

[0064] In this regard, the at least one linear polyester preferably has a weight-average molecular weight of 2,000-30,000 g / mol, more preferably 2,500-25,000 g / mol, even more preferably 3,000-20,000 g / mol, and very preferably 3,000-17,000 g / mol, as determined according to DIN EN ISO 16014-5.

[0065] When the base material B is selected from polyester, it is advantageous that the coating composition comprises at least two different linear polyesters P1 and P2, wherein the weight-average molecular weight of polyester P1 is 2000-9000 g / mol, preferably 3000-6000 g / mol, and the weight-average molecular weight of linear polyester P2 is 10000-20000 g / mol, preferably 14000-16000 g / mol, wherein the weight-average molecular weight is determined according to DIN EN ISO 16014-5 in each case.

[0066] A suitable weight ratio of the at least one linear polyester P1 to the at least one polyester P2 is, for example, 2:1 to 1:2, preferably 2:1 to 1:1.

[0067] The hydroxyl value of the at least one linear polyester is preferably 20-100 mg KOH / g, more preferably 30-80 mg KOH / g, and even more preferably 40-70 mg KOH / g, as determined according to DIN 53240-3:2016-03.

[0068] The glass transition temperature (Tg) of a suitable linear polyester is 30-80°C, preferably 40-70°C, and more preferably 45-65°C, determined by differential scanning calorimetry according to DIN EN ISO 11357-2:2014.

[0069] The linear polyester is commercially available, for example, under the trade names Dynapol L 205 (Degussa) and Uralac SH970 (DSM).

[0070] Advantageously, the coating composition comprises at least one base material B, preferably the at least one polyepoxide or the at least one linear polyester, in a total amount of 1-40% by weight solids, preferably 5-30% by weight solids, and most preferably 15-20% by weight solids, based on the total amount of the coating composition in each case. Using the above-mentioned amount of base material ensures the formation of a sufficient and stable film on the substrate. Silane compound SC:

[0071] In the case that the coating composition of the present invention is a conversion coating, it preferably contains at least one silane compound SC.

[0072] The silane compound SC is preferably selected from silane compounds containing at least one primary amino group and at least one hydrolyzable alkoxy group.

[0073] The particularly preferred silane compound SC has the general formula (I):

[0074] NH2-R 1 -YR 2 -Si(R a ) 3-x (R b ) x (I)

[0075] in:

[0076] R 1 R 2 Each is an alkylene group containing 1-10 carbon atoms;

[0077] R a It is an alkoxy group containing 1-4 carbon atoms;

[0078] R b It is an alkyl group containing 1-4 carbon atoms or an alkoxy group containing 1-4 carbon atoms;

[0079] Y represents oxygen, sulfur, or NR. 3 Group, wherein R 3 It is hydrogen or an alkyl group containing 1-4 carbon atoms; and x is 0-1.

[0080] Preferably, R 1 C2 alkylene and / or R 2 It is a C3 alkylene group.

[0081] Furthermore, R in general formula (I) a It is an alkoxy group containing one carbon atom, and x is 0.

[0082] In general formula (I), Y represents an NH group.

[0083] The particularly preferred silane compound SC is (3-(2-aminoethylamino)propyltrimethoxysilane, i.e., R 1 It is a C2 alkylene group, R 2 It is a C3 alkylene group, R a It is an alkoxy group containing one carbon atom, x is 0, and Y is an NH group.

[0084] The coating composition preferably contains 2-20% by volume, more preferably 5-15% by volume, of at least one silane compound SC, preferably a silane compound of general formula (I), based on the total volume of the coating composition in each case. The coating composition is obtained by combining the above-mentioned amount of silane compound SC with a graphene oxide (GO-M) containing at least one monovalent metal ion selected from lithium, potassium, and mixtures thereof, which provides excellent adhesion and corrosion resistance to substrates treated with the composition.

[0085] Solvent S1:

[0086] The waterborne coating composition of the present invention contains at least one solvent S1 as a third mandatory component (c).

[0087] Suitable solvent S1 is selected from water, aliphatic and / or aromatic hydrocarbons, ketones, esters, or mixtures thereof. When solvent S1 is selected from water, the coating composition is an aqueous coating composition. When the coating composition of the present invention is a solvent-based coating composition, it contains at least one organic solvent S1. The organic solvent used does not inhibit the crosslinking of the coating composition of the present invention and / or does not chemically react with other components of the coating composition of the present invention. Therefore, those skilled in the art can readily select a suitable solvent based on its known solubility and reactivity. Particularly preferred organic solvent S1 is selected from xylene and / or methoxypropanol or aliphatic hydrocarbons, as well as methoxypropyl acetate and butyl diethylene glycol acetate and diesters.

[0088] The coating composition of the present invention is preferably a liquid coating composition at a temperature of 23°C. Therefore, the coating composition advantageously contains 10-95% by weight, preferably 20-90% by weight, and very preferably 25-60% by weight of the at least one solvent S1, in each case based on the total weight of the coating composition.

[0089] Crosslinking agent CL:

[0090] Since the preferred base material B described above typically does not possess film-forming properties, a corresponding crosslinking agent is additionally used when using this resin. Therefore, the coating composition of the present invention preferably further comprises at least one crosslinking agent CL. The crosslinking agent CL is preferably selected from amino resins, unblocked polyisocyanates, blocked polyisocyanates, polycarbodiimides, phenalamine curing agents, polyaminoamide resins, melamine resins, resins containing carboxylic acid groups, β-hydroxyalkylamides, tris(alkoxycarbonylamino)triazines, and mixtures thereof, with phenalamine curing agents and / or polyaminoamide resins and / or blocked or aromatic polyisocyanates and / or melamine resins being particularly preferred.

[0091] If an epoxy resin is used as base material B, then the at least one crosslinking agent CL is preferably selected from phenolic amines and / or polyaminoamide compounds. Phenolic amines and polyaminoamides, belonging to the general category of "polyamines," are a collective term for organic compounds having two or more amino groups, such as diamines or triamines. In addition to amino groups, the compounds in this example have aliphatic or aromatic parent structures—that is, they consist of, for example, amino and aliphatic groups or amino and aromatic groups (aliphatic or aromatic polyamines). Polyamines may, of course, also contain aliphatic and aromatic units, and may optionally contain other functional groups. Examples of aliphatic polyamines are diethylenetriamine, triethylenetetramine, 3,3′,5-trimethylhexamethylenediamine, 1,2-cyclohexanediamine, and isophoronediamine. Examples of aromatic amines are methylenediphenylamine and 4,4-diaminodiphenyl sulfone. The superordinate term "polyamine" also encompasses organic compounds, for example, prepared by reacting aliphatic or aromatic polyamines (i.e., so-called basic polyamines) with other organic compounds through the reaction of at least some of their amino groups, thereby affecting various properties, such as the reactivity and / or solubility of the compound, and / or the properties (e.g., surface hardness) of the coating prepared from the coating composition. The compound then constitutes an adduct, which, if it still contains at least two amino groups, may be called a polyamine adduct or modified polyamine. Of course, they also have higher molecular weights than the aforementioned polyamines, thus reducing their harmful health effects. The polyamine adduct is typically the product of the reaction of aliphatic and / or aromatic polyamines with polyepoxides (e.g., the aforementioned epoxy resins), or with independent bifunctional compounds such as bisphenol A diglycidyl ether, in which case a stoichiometric excess of amino groups is used compared to the epoxy groups. These adducts are then used to cure the epoxy resin in the actual coating composition. A known example is the reaction product of 3,3′,5-trimethylhexamethylenediamine as a basic polyamine with bisphenol A diglycidyl ether as an epoxy resin. For example, conventional polyaminoamides, which are polymers prepared, for instance, by condensing polyamines previously described as basic polyamines with polycarboxylic acids, more particularly dicarboxylic acids.

[0092] In one or more embodiments, the at least one crosslinking agent CL, preferably a polyamine, has an amine value of 100-300 mg KOH / g solid, preferably 140-200 mg KOH / g solid, as determined according to DIN 16945:1989-03.

[0093] Further preferably, the at least one crosslinking agent CL, preferably a polyamine, has an active H equivalent (the mass of the polyamine per mole of active hydrogen (NH group, i.e., hydrogen on the primary and secondary amine groups) of 15-400 g / Eq. solids, more particularly 150-300 g / Eq. solids (measured by determining the primary and secondary amine groups according to ASTM D2073).

[0094] The polyamine or polyamine adduct or polyaminoamide used as a reactant and / or crosslinking agent in epoxy resins may be available, for example, under the trade name Beckopox from Cytec, or under the trade name Cardolite (e.g., Cardolite NC-562) from Cardolite.

[0095] If an OH-functional resin, such as a polyester or an OH-functional polyurethane, is used as the base material B, then the at least one crosslinking agent CL is preferably selected from free and / or blocked polyisocyanates and / or melamine resins based on hexamethylene diisocyanate or isophorone diisocyanate. The blocked polyisocyanate preferably has a deblocking temperature of 110-185°C, very preferably 135-155°C, and therefore can be completely deblocked at a curing temperature of 180-240°C. Suitable polyisocyanates include, but are not limited to, alkylene polyisocyanates, such as hexamethylene diisocyanate, 4-and / or 2,4,4-trimethylhexamethylene diisocyanate, dodecamethyl diisocyanate, 1,4-diisocyanate-cyclohexane, 1-isocyanate-3,3,5-trimethyl-5-isocyanate-methylcyclohexane (isophorone diisocyanate), 2,4′-and / or 4,4′-diisocyanate-dicyclohexylmethane, 3-isocyanate-methyl-3,5,5-trimethylcyclohexyl isocyanate, aromatic polyisocyanates, such as 2,4′-and / or 4,4′-diisocyanate-diphenylmethane, 2,4-and / or 2,6-diisocyanate-toluene, naphthylene diisocyanate, and mixtures of these polyisocyanates. Typically, polyisocyanates having an average of three or more isocyanate groups are used; these can be derivatives or adducts of diisocyanates. Available polyisocyanates can be obtained by reacting excess isocyanate with water, polyols (e.g., ethylene glycol, propylene glycol, 1,3-butanediol, neopentyl glycol, 2,2,4-trimethyl-1,3-pentanediol, hexamethylenediol, cyclohexanediol, hydrogenated bisphenol A, trimethylolpropane, trimethylolethane, 1,2,6-hexanetriol, glycerol, sorbitol, or pentaerythritol), or by reacting isocyanate with itself to form isocyanurates. Furthermore, polyisocyanates containing biuret groups, isocyanurate groups, carbamate groups, carbodiimide groups, ureacarbate groups, and urea-diketone groups can be used. Particularly preferred are hexamethylene diisocyanate or isophorone diisocyanate, as well as blocked polyisocyanates based on hexamethylene diisocyanate or isophorone diisocyanate.

[0096] The at least one blocked polyisocyanate preferably has an NCO content of 4-12%, more preferably 4-10%, and very preferably 4.6-8.6%, based on the solid content in each case.

[0097] The melamine resin is preferably selected from methanol, ethanol, propanol and / or butanol, more preferably methanol-etherified melamine resin, and contains an average of 0.05-3, preferably 0.07-2.5, and most preferably 0.08-2 imino groups.

[0098] Preferably, the coating composition contains 1-30% by weight, preferably 5-20% by weight, and most preferably 10-15% by weight of the at least one crosslinking agent CL, based on the total weight of the coating composition in each case. Using the aforementioned crosslinking agent in such amounts results in sufficient crosslinking of the coating composition of the present invention, thus contributing to the corrosion inhibition properties of graphene oxide (GO-M) containing at least one monovalent metal ion selected from lithium, potassium, and mixtures thereof.

[0099] Curing catalyst:

[0100] To accelerate curing time, the coating composition of the present invention may further contain at least one curing catalyst.

[0101] Suitable curing catalysts are selected from functionalized phenols, tin (IV) compounds, bismuth compounds, blocked or unblocked sulfonic acid compounds, and mixtures thereof, preferably 2,4,6-tris(dimethylaminomethyl)phenol or tin (III) alkoxylates and / or sulfonic acid compounds. Suitable sulfonic acid compounds are selected from dinonylnaphthalene monosulfonic acid, dinonylnaphthalene disulfonic acid, and / or dodecylbenzenesulfonic acid.

[0102] The coating composition preferably contains 0.05-5% by weight, more preferably 0.1-3% by weight, and most preferably 0.3-2.5% by weight of the at least one curing catalyst, in each case based on the total weight of the coating composition.

[0103] pigment / filler:

[0104] The coating compositions of the present invention may further comprise at least one pigment and / or filler. The pigment may be selected from color pigments, effect pigments, and corrosion-inhibiting pigments known to those skilled in the art.

[0105] The term "pigment" is known to those skilled in the art, for example, by DIN 55945 (dated October 2001). Within the meaning of this invention, "pigment" preferably refers to compounds in powder or flake form that are substantially, preferably completely insoluble in the surrounding medium, such as the coating compositions of this invention. Pigments as defined herein differ from "fillers" at least in their refractive index, with pigments having a refractive index ≥1.7.

[0106] Suitable pigments are preferably selected from organic and inorganic coloring pigments (including black and white pigments), effect pigments, and mixtures thereof.

[0107] Examples of suitable inorganic colorants are white pigments, such as zinc white, zinc sulfide, or zinc barium white; black pigments, such as carbon black, iron manganese black, or spinel black; colored pigments, such as chromium oxide, hydrated chromium oxide green, cobalt green or ultramarine green, cobalt blue, ultramarine blue or manganese blue, ultramarine violet or cobalt violet and manganese violet, iron oxide red, cadmium sulfide selenide, molybdenum red or ultramarine red; iron oxide brown, mixed brown, spinel phase and corundum phase or chrome orange; or iron oxide yellow, nickel titanium yellow, chrome titanium yellow, cadmium sulfide, zinc cadmium sulfide, chrome yellow or bismuth vanadate. Other examples of inorganic colorants are, for example, alumina, alumina hydrate, especially boehmite, titanium dioxide, zirconium oxide, cerium oxide and mixtures thereof. Examples of suitable organic colorants are monoazo pigments, diazo pigments, anthraquinone pigments, benzimidazole pigments, quinacridone pigments, quinoline ketone pigments, diketopyrrolopyrrole pigments, di... Phthalate pigments, tanninone pigments, isoindoline pigments, isoindolineone pigments, azomethyl alkali pigments, thioindigo pigments, metal complex pigments, perinone pigments, perylene pigments, phthalocyanine pigments, or aniline black. Effect pigments include metallic effect pigments, as well as pearlescent pigments, etc.

[0108] The term "filler" is known to those skilled in the art, for example, by DIN 55945 (dated October 2001). Within the meaning of this invention, "filler" preferably refers to a substance that is substantially insoluble, preferably completely insoluble, in the coating compositions of this invention, and more particularly used to increase volume. Within the meaning of this invention, "filler" differs from "pigment" at least in its refractive index; the refractive index of the filler is <1.7. Any conventional filler known to those skilled in the art can be used. Examples of suitable fillers are kaolin, dolomite, calcite, chalk, calcium sulfate, barium sulfate, graphite, silicates such as magnesium silicate, more particularly the corresponding layered silicates such as lithium montmorillonite, bentonite, montmorillonite, talc and / or mica, silicates, more particularly fumed silica, hydroxides such as aluminum hydroxide or magnesium hydroxide, or organic fillers such as textile fibers, cellulose fibers, polyethylene fibers, or polymer powders; further details can be found in [link to relevant documentation]. Lexikon Lacke und Druckfarben, Georg Thieme Verlag, 1998, p. 250 and thereafter, “Fillers”.

[0109] Although the above-described pigments and fillers can be suitably used in the coating compositions of the present invention, such pigments containing environmentally problematic elements such as Pb, Cd, Cr, Cu, Mo, Hg, Se, or Zn are less preferred and are most preferably excluded from the coating compositions of the present invention.

[0110] The at least one pigment and / or filler is preferably contained in a total amount of 10-70% by weight, more preferably 20-60% by weight, and very preferably 35-50% by weight, in each case based on the total weight of the coating composition. If more than one pigment and / or filler is present in the coating composition of the present invention, the above amounts refer to the sum of the amounts of all pigments and / or fillers contained in the coating composition.

[0111] If the coating composition of the present invention contains at least one color pigment, such as titanium dioxide, iron oxide, zinc oxide or organic pigment, then such pigment is preferably present in a total amount of 5-20% by weight, more preferably 5-15% by weight, and very preferably 7.5% by weight, based on the total weight of the coating composition in each case.

[0112] The appropriate amount of corrosion-inhibiting pigment is 2-10% by weight, preferably 4-8% by weight, very preferably 4-6% by weight, depending on the coating composition in each case.

[0113] The coating composition preferably contains a pigment to base ratio of 10:1 to 1:10, more preferably 6:1 to 1:6, even more preferably 5:1 to 1:2, and very preferably 7:3 or 2:1 to 1:2.

[0114] additive:

[0115] The coating composition may further comprise at least one additive commonly used in water-based and solvent-based coating compositions. Suitable coating additives are selected from (i) UV absorbers; (ii) light stabilizers, such as HALS compounds, benzotriazoles, or oxaloanilines; (iii) rheology modifiers, such as sagging control agents (urea crystallization modified resins), organic thickeners, and inorganic thickeners; (iv) free radical scavengers; (v) slip additives; (vi) polymerization inhibitors; (vii) defoamers; (viii) wetting agents; (ix) fluorinated compounds; (x) tackifiers; (xi) leveling agents; (xii) film-forming aids, such as cellulose derivatives; (xiii) flame retardants; and (xiv) mixtures thereof.

[0116] Examples of suitable wetting agents are polycarboxylic acid polymers, high molecular weight block copolymers, acrylic copolymers, unsaturated polyaminoamides, carboxylic acid esters, and mixtures thereof. Wetting agents are typically contained in a total amount of 0.1-1.5% by weight, preferably 0.2-0.5% by weight, based on the total weight of the coating composition in each case.

[0117] Suitable defoamers are silicone-free polymers, polymethylalkylsiloxanes, polysiloxanes, acrylic resins, and mixtures thereof that have defoaming properties. The defoamer is typically contained in a total amount of 0.1-1.5% by weight, very preferably 0.25-0.75% by weight, based on the total weight of the coating composition in each case.

[0118] Other additives listed above are preferably used in conventional amounts, for example, 0.1-20% by weight based on the total weight of the coating composition.

[0119] In one or more specific embodiments, the coating compositions of the present invention are completely free of chromium-containing corrosion inhibitors. In a more specific embodiment, the coating compositions of the present invention are completely free of chromium and chromium-containing substances, i.e., they contain no more than trace amounts and impurities of chromium and chromium-containing substances, and very preferably contain said substances at 0% by weight based on the total weight of the coating composition.

[0120] Properties of the coating composition of the present invention:

[0121] If the coating composition of the present invention is applied by spraying, its Ford viscosity in a DIN 4 cup at 20°C is preferably 15-50 seconds, more preferably 20-45 seconds, and very preferably 25-40 seconds.

[0122] If the coating composition of the present invention is formulated as an dip coating composition, it preferably has the effect of being coated at 23°C and for 150 seconds. -1 Viscosities of 200-1000 mPa*s at shear rates, with a very preferred viscosity of 500-800 mPa*s, were determined according to DIN EN ISO 3219:1994-10 and DIN 53019-2:2001-02.

[0123] If the coating composition of the present invention is formulated as a primer composition suitable for roll coating, it preferably has a viscosity of 12-120 seconds / 4 mm as determined according to DIN 53211-4.

[0124] The solid content of the coating composition of the present invention can be varied according to the specific requirements. The solid content is mainly determined by the viscosity required for application and can be adjusted by a person skilled in the art based on his or her general technical knowledge. Preferably, the solid content of the coating composition of the present invention is 20-90% by weight, more particularly 30-80% by weight, even more particularly 40-60% by weight or 50-70% by weight, as determined according to DIN EN ISO 3251:2008-06.

[0125] The coating compositions of the present invention can be formulated into primer compositions, first and second coat mixed primer compositions, filler coating compositions, conversion coating compositions, electrophoretic coating compositions, or dip coating compositions. Depending on the specific application of the coating compositions of the present invention, suitable binder B and solvent S1 are selected to adapt the film-forming and application properties to the specific intended use.

[0126] The coating composition of the present invention can be formulated into a single-component (1C) or multi-component system, that is, a system containing at least two individual components.

[0127] In a single-component (1C) system, the components to be crosslinked (e.g., the organic polymer (B) as a base and the crosslinking agent CL) exist side-by-side, i.e., in one component. A prerequisite for this is that the components to be crosslinked only react with each other at relatively high temperatures and / or when exposed to photochemical radiation.

[0128] In a two-component (2C) system, the components to be crosslinked (e.g., an organic polymer as base B and a crosslinking agent CL) exist separately in at least two components and are mixed shortly before the coating composition is applied. This form is chosen when the components to be crosslinked react with each other even at room temperature.

[0129] Preferably, the coating composition of the present invention is formulated as a two-component (2C) system. The system preferably contains at least one base material B in a suitable solvent S1 in the first component, and at least one crosslinking agent CL in a suitable solvent in the second component. Graphene oxide (GO-M) containing at least one monovalent metal ion selected from lithium, potassium, and mixtures thereof may be included in either the first or second component. Preferably, graphene oxide (GO-M) containing at least one monovalent metal ion selected from lithium, potassium, and mixtures thereof is included in the first component.

[0130] Method for preparing the coating composition of the present invention

[0131] Another subject of the present invention is a method for preparing the coating composition of the present invention, the method comprising the following steps:

[0132] (a) Preparing a dispersion D of at least one graphene oxide (GO-M) containing at least one monovalent metal ion selected from lithium, potassium, and mixtures thereof in at least one solvent S2; and

[0133] (b) Add the dispersion D prepared in step (a) to a mixture comprising at least one base material B and / or at least one silane compound SC and at least one solvent S1.

[0134] A dispersion of at least one graphene oxide (GO-M) containing at least one monovalent metal ion selected from lithium, potassium, and mixtures thereof in the at least one solvent S2 can be achieved by adding a corresponding graphene oxide (GO-M) containing at least one monovalent metal ion selected from lithium, potassium, and mixtures thereof to the at least one solvent S2 and dispersing the graphene oxide (GO-M) containing at least one monovalent metal ion selected from lithium, potassium, and mixtures thereof (e.g., by ultrasonic treatment).

[0135] The dispersion D prepared in step (a) preferably contains 0.05-5% by weight, more preferably 1-4% by weight, and very preferably 1.5-3% by weight of at least one graphene oxide (GO-M) containing at least one monovalent metal ion selected from lithium, potassium, and mixtures thereof, based on the total weight of the dispersion in each case. The above amounts allow for a sufficiently high dispersion of the graphene oxide (GO-M) containing at least one monovalent metal ion selected from lithium, potassium, and mixtures thereof in solvent S2, such that introducing the graphene oxide (GO-M) containing at least one monovalent metal ion selected from lithium, potassium, and mixtures thereof into the coating composition of the present invention does not significantly affect its high solids content.

[0136] Suitable solvent S2 for the dispersion of graphene oxide (GO-M) containing at least one monovalent metal ion selected from lithium, potassium and mixtures thereof in step (a) is selected from aliphatic and / or aromatic hydrocarbons, ketones, esters or mixtures thereof, preferably esters, and very preferably ethyl acetate.

[0137] Preferably, dispersion D contains 95-99.95% by weight, more preferably 96-99% by weight, and very preferably 97-98.5% by weight of the at least one solvent S2, based on the total weight of the dispersion in each case. Therefore, the dispersion prepared in step (a) of the method of the invention advantageously consists of graphene oxide (GO-M) containing at least one monovalent metal ion selected from lithium, potassium, and mixtures thereof, and solvent S2.

[0138] The appropriate total amount of dispersion D added in step (b) is 0.1-10% by weight, preferably 1-7% by weight, very preferably 2-4% by weight, based on the total weight of the resulting coating composition in each case.

[0139] The contents described regarding the coating composition of the present invention are compared with other preferred embodiments applicable to the method of the present invention.

[0140] The method of the present invention for preparing at least one coating on a substrate (S):

[0141] The coating compositions of the present invention, as well as the coating compositions prepared by the method of the present invention, can be used to form coatings on substrates.

[0142] In the method of the present invention, at least one coating is formed on the substrate (S) by the following steps:

[0143] (i) Applying the coating composition of the present invention or the coating composition prepared by the method of the present invention directly onto the substrate (S);

[0144] (ii) A film is formed from the coating composition applied in step (i) by curing the coating composition; and

[0145] (iii) Optionally, at least one other coating composition is applied to the coating formed in step (ii) and the coating composition is cured.

[0146] The substrate (S) is preferably selected from metal substrates, metal substrates coated with a conversion coating, and mixtures thereof. In cases where the coating composition of the present invention contains at least one silane compound SC, a metal substrate is preferably used in step (i). If the coating composition of the present invention does not contain the at least one silane compound SC, a conversion coating may be applied to the substrate prior to step (i) to improve the adhesion of the coating composition of the present invention by using conversion coating compositions known in the art, such as Granodine 1455 or zinc phosphate coatings used in the method of the present invention. The conversion layer is preferably 20-300 nm thick and may be applied, for example, by a chemical coating machine or by spraying / extrusion.

[0147] The substrate (S) may be pretreated, for example by cleaning, before step (i) of the method of the present invention or before applying the conversion coating in any conventional manner. Cleaning may be performed mechanically, such as by wiping, grinding and / or polishing, and / or by acid pickling, by initial wet etching in an acid or alkali bath, or by chemical treatment, such as hydrochloric acid or sulfuric acid. Cleaning may also be performed using organic solvents or aqueous cleaning agents.

[0148] According to the first alternative, the preferred metal substrate is aluminum or aluminum alloys, for example, more particularly, aluminum-copper alloys selected from the 2000er, 5000er, 6000er, or 7000er series, with AA6014, AA6016, AA6022, AA6111, AA6061, AAC7075, and AA5083 alloys being particularly preferred, as well as non-alloy and alloy steels commonly used in the automotive field. The substrate itself can be of any shape, i.e., a simple sheet metal or a complex component, such as an automobile body and its parts.

[0149] According to the second alternative, the preferred metal substrate is structural steel, which is optionally coated with a metal coating and is typically used in coil coating processes. Suitable metal coatings are selected from zinc / iron alloys, zinc / aluminum alloys, aluminum / zinc alloys, zinc-magnesium alloys, zinc / chromium or zinc / nickel alloys, and zinc doped with aluminum.

[0150] Step (i):

[0151] In step (i) of the method of the present invention, the coating composition of the present invention or a coating composition prepared according to the method of the present invention is applied directly to a substrate. As used herein, the phrase "applied directly to a substrate" means that no other coating or conversion coating capable of forming an organic polymer matrix is ​​applied in the method of the present invention prior to the application of the coating composition. However, this does not preclude the use of a substrate already comprising a coating, such as a previously disclosed conversion coating.

[0152] Depending on the substrate, the coating composition can be applied, for example by known techniques such as spraying, scraping, spreading, pouring, dipping, impregnation, dripping, or roller coating. In the case of metal substrates used in the automotive industry, spraying or scraping techniques are employed.

[0153] When the coating composition applied in step (i) is used in a roll coating process, the composition can be applied by spraying, flow coating, or roll coating. Roll coating is particularly advantageous among these application techniques and is therefore preferred according to the invention. Each application step in roll coating can be performed using two or more rollers. Two to four rollers are preferred, especially two. In roll coating, a rotating pick-up roller is immersed in a container of the coating of the invention to pick up the coating to be applied. The material is transferred from the pick-up roller directly or via at least one transfer roller to the rotating application roller. The coating is transferred from the latter roller to the roll material via co-directional or counter-directional contact transfer. Alternatively, the coating of the invention can be pumped directly into the gap between the two rollers, sometimes referred to as gap feeding. Counter-directional contact transfer or counter-directional roll coating processes are advantageous according to the invention and are therefore preferred.

[0154] Step (ii):

[0155] In step (ii) of the method of the present invention, a polymer film is formed by curing the applied coating composition using known techniques. Physical or thermal curing is preferred because both physical and thermal curing systems are preferred in the context of the present invention. Thermal curing of an externally crosslinked 2C system is particularly preferred.

[0156] According to the first alternative, thermosetting is preferably carried out at a temperature of 20-25°C. These relatively low curing temperatures are possible due to the use of a base / crosslinking agent system, namely an epoxy resin / polyamine system. The thermosetting time can vary considerably depending on the specific circumstances, for example, from 5 minutes to 5 days, and more particularly from 50-70 minutes.

[0157] According to the second alternative, curing is preferably carried out at a temperature of 140-240°C using convective heat transfer, near-infrared or infrared radiation, and / or induction. This curing temperature is preferred in a coil coating process, wherein a continuous coil onto which the coating composition of the present invention is applied is passed through a convection oven, such that the coil reaches a peak metal temperature (PTM) of 200-240°C at the end of the oven. The residence time in this oven is typically 20-60 seconds, depending on the belt speed and the material of the coil. Preferably, a forced-air oven with a length of 30-50 m, particularly 35-45 m, is used. The temperature of the forced air is preferably below 300°C, particularly below 280°C.

[0158] Depending on the specific circumstances and the base / crosslinking agent system used, the coating may be flash-evaporated for 1-60 minutes at room temperature (approximately 15-25°C) and / or dried for 1-60 hours at a slightly higher temperature, such as 30-80°C, before curing. In the context of this invention, flash evaporation and drying refer to the evaporation of organic solvents and / or water, resulting in a dry but not yet fully crosslinked coating.

[0159] The dry film thickness of the cured coating obtained after step (ii) is preferably 1-100 μm, more preferably 2-90 μm, and very preferably 55-75 μm or 3-30 μm. If the method of the present invention is used to coat substrates used in the automotive and aerospace fields, a higher dry film thickness of 15-100 μm is used, while in the case of roll coating, a dry film thickness of less than 10 μm is preferred.

[0160] Step (iii):

[0161] In optional step (iii) of the invention, at least one other coating composition is applied to the cured coating film formed in step (ii), and said other coating is cured. Prior to step (iii), the coated substrate obtained after step (ii) may be cooled, for example, by spraying water onto the coated substrate. This is particularly preferred if a high curing temperature is used in step (ii).

[0162] The at least one other coating is obtained by applying any conventional and known coating capable of forming a polymer-based coating. The above-described application method can also be used for coatings that overlay the coatings of the present invention, except in the case that they are powder coatings or electrophoretic coatings, in which case conventional special application methods are used, such as electrostatic powder spraying in the case of low-speed roll-to-roll or powder cloud chamber process in the case of high-speed roll-to-roll, as well as cathodic electrodeposition coatings.

[0163] The coatings are then cured using the same known and conventional techniques. Each coating can also be prepared by applying them sequentially with each layer partially cured, and then curing them in a final co-curing process (wet-on-wet method). Alternatively, each coating can be fully cured in each case.

[0164] The method of the present invention preferably includes applying and curing at least one other coating to form a multilayer coating. In the automotive industry, as is known, the other coating can be a conventional two-coat primer layer, a base coat, and a clear coat. Therefore, it is preferred to prepare a multilayer coating that, in addition to the cured coating prepared from the coating composition of the present invention, includes at least one two-coat primer layer, a base coat, and a clear coat, or consists of said coatings. In coil coating or the aerospace industry, said at least one other coating composition can be a typical single-coat topcoat composition, such as based on (two-component) polyurethane, polyester, epoxy, melamine, or phenolic resin systems. Therefore, in an equally preferred variant of the present invention, a multilayer coating is prepared that, in addition to the cured coating prepared from the coating composition of the present invention, includes a topcoat layer, or consists of both layers.

[0165] If the other coating is a second primer, base coat, clear coat, or topcoat commonly used in automobiles, then the curing in step (iii) is preferably carried out at a temperature of 50-70°C for 20-40 minutes. The final dry film thickness of the second primer layer and / or base coat and / or clear coat layer is preferably 40-100 μm in each case, more preferably 45-90 μm, and very preferably 50-60 μm.

[0166] If the other coating is a topcoat for coil coating or aerospace applications, the curing in step (iii) is preferably carried out in a convection oven at a temperature of 250-270°C (PMT), as described previously in step (ii). The dwell time is preferably about 10-30 seconds, after which the coated substrate can be cooled by spraying water onto it. The dry film thickness of the resulting topcoat layer is preferably 1-15 μm, more preferably 1-10 μm, and very preferably 1-5 μm.

[0167] After the coated rolls of the present invention are prepared, they can be wound up and then further processed in another location; or, when they come directly from the roll coating operation, they can be further processed. For example, they can be laminated with plastic or provided with a removable protective film. After being cut into parts of appropriate size, they can be shaped. Examples of suitable shaping methods include pressing and deep drawing.

[0168] The description of the coating composition and the method for preparing the coating composition of the present invention is adapted to other preferred embodiments of the method of the present invention.

[0169] The coating or multilayer coating (MC) of the present invention:

[0170] The result after step (ii) or (iii) of the method of the present invention is the coating or multilayer coating (MC) of the present invention.

[0171] The descriptions of the coating compositions, methods for preparing the coating compositions, and methods for preparing coated substrates of the present invention are applicable to other preferred embodiments of the coatings or multilayer coatings of the present invention.

[0172] Applications of this invention:

[0173] The final subject of this invention is the use of at least one graphene oxide (GO-M) containing at least one monovalent metal ion selected from lithium, potassium, and mixtures thereof in a composition to improve the corrosion resistance of said composition.

[0174] Preferably, the composition is a coating composition, more preferably an organic coating composition.

[0175] According to an alternative embodiment, the composition is a sealant composition.

[0176] The contents of the coating composition of the present invention, the method for preparing the coating composition of the present invention, the method for preparing the coating substrate of the present invention, and the coating substrate of the present invention are compared with other preferred embodiments applicable to the use of the present invention.

[0177] In particular, the present invention is described by means of the following embodiments:

[0178] Implementation Scheme 1: A coating composition comprising:

[0179] a) At least one graphene oxide (GO-M) containing at least one monovalent metal ion selected from lithium, potassium and mixtures thereof;

[0180] b) at least one base material B and / or at least one silane compound SC; and

[0181] c) At least one solvent S1.

[0182] Implementation Scheme 2: The coating composition according to Implementation Scheme 1, wherein the monovalent metal ion is lithium.

[0183] Implementation Scheme 3: The coating composition according to Implementation Scheme 1 or 2, wherein the coating composition contains, in a total amount of 0.1 ppm to 5% by weight, preferably 0.1 ppm to 1% by weight, more preferably 0.1-500 ppm, even more preferably 0.3-50 ppm, very preferably 0.35-1 ppm, of at least one graphene oxide (GO-M) containing at least one monovalent metal ion selected from lithium and / or potassium, preferably a lithium-ion-containing graphene oxide, based on the total weight of the coating composition in each case.

[0184] Implementation Scheme 4: The coating composition according to any one of the preceding embodiments, wherein the at least one base material B is selected from (i) poly(meth)acrylate, more particularly hydroxyl-functional and / or carboxylic acid-functional and / or amine-functional poly(meth)acrylate, (ii) polyurethane, more particularly hydroxyl-functional and / or carboxylic acid-functional and / or amine-functional polyurethane, (iii) linear or branched polyester or polyamide-modified polyester, more particularly linear or branched polyester polyol, (iv) polyether, more particularly polyether polyol, (v) polyepoxide, (vi) phenoxy resin, (vii) copolymer of said polymer, and (vi) mixtures thereof, preferably polyepoxide, linear or branched polyester and / or polyester-polyurethane copolymer.

[0185] Implementation Scheme 5: The coating composition according to any one of the preceding embodiments, wherein the at least one base material B has an epoxy equivalent (EEW) of 100-400 g / Eq., preferably 150-350 g / Eq., very preferably 200-300 g / Eq., as determined according to DIN EN ISO 3001:1999-11.

[0186] Implementation Scheme 6: The coating composition according to any one of the preceding embodiments, wherein the at least one base material B is selected from a mixture of two different polyepoxides, wherein the dynamic viscosity of the first polyepoxide B1 is 0.5-2 Pa*s (determined according to ASTM D 445-06), and the dynamic viscosity of the second polyepoxide B2 is 800-1400 mPa*s (determined according to DIN EN ISO 3219:1994-10 at a shear rate of 500 1 / s and 23°C).

[0187] Implementation Scheme 7: The coating composition according to any one of Implementation Schemes 1-4, wherein the at least one base material B is selected from linear and / or branched polyesters, preferably linear polyesters.

[0188] Implementation Scheme 8: The coating composition according to Implementation Scheme 7, wherein the weight average molecular weight of the at least one linear polyester is 2000-30000 g / mol, preferably 2500-25000 g / mol, more preferably 3000-20000 g / mol, and very preferably 3000-17000 g / mol, as determined according to DIN EN ISO16014-5.

[0189] Implementation Scheme 9: A coating composition according to Implementation Scheme 7 or 8, wherein the coating composition comprises at least two different linear polyesters P1 and P2, polyester P1 having a weight-average molecular weight of 2000-9000 g / mol, preferably 3000-6000 g / mol, and linear polyester P2 having a weight-average molecular weight of 10000-20000 g / mol, preferably 14000-16000 g / mol, wherein the weight-average molecular weight is determined according to DIN EN ISO 16014-5 in each case.

[0190] Implementation Scheme 10: The coating composition according to Implementation Scheme 9, wherein the coating composition comprises a weight ratio of at least one linear polyester P1 to at least one polyester P2 of 2:1 to 1:2, preferably 2:1 to 1:1.

[0191] Implementation Scheme 11: The coating composition according to Implementation Schemes 7-10, wherein the hydroxyl value of the at least one linear polyester is 20-100 mg KOH / g, preferably 30-80 mg KOH / g, more preferably 40-70 mg KOH / g, as determined according to DIN53240-3:2016-03.

[0192] Implementation Scheme 12: The coating composition according to any one of Implementation Schemes 7-11, wherein the glass transition temperature Tg of the at least one linear polyester is 30-80°C, preferably 40-70°C, more preferably 45-65°C, as determined according to DIN ENISO 11357-2:2014.

[0193] Implementation Scheme 13: A coating composition according to any one of the preceding embodiments, wherein the coating composition comprises at least one base material B, preferably the at least one polyepoxide or the at least one linear polyester, in a total amount of 1-40% by weight solids, preferably 5-30% by weight solids, very preferably 15-20% by weight solids, based on the total amount of the coating composition in each case.

[0194] Implementation Scheme 14: The coating composition according to any one of the preceding embodiments, wherein the silane compound SC is selected from silane compounds comprising at least one primary amino group and at least one hydrolyzable alkoxy group.

[0195] Implementation Scheme 15: The coating composition according to any one of the preceding embodiments, wherein the silane compound SC has the general formula (I):

[0196] NH2-R 1 -YR 2 -Si(R a ) 3-x (R b ) x (I)

[0197] in:

[0198] R 1 R 2 Each is an alkylene group containing 1-10 carbon atoms;

[0199] R a It is an alkoxy group containing 1-4 carbon atoms;

[0200] R b It is an alkyl group containing 1-4 carbon atoms or an alkoxy group containing 1-4 carbon atoms;

[0201] Y represents oxygen, sulfur, or NR. 3 Group, wherein R 3 It is hydrogen or an alkyl group containing 1-4 carbon atoms; and x is 0-1.

[0202] Implementation Scheme 16: The coating composition according to Implementation Scheme 15, wherein R 1 C2 alkylene and / or R 2 It is a C3 alkylene group.

[0203] Implementation Scheme 17: The coating composition according to Implementation Scheme 15 or 16, wherein R a It is an alkoxy group containing one carbon atom, and x is 0.

[0204] Implementation Scheme 18: The coating composition according to any one of Implementation Schemes 15-17, wherein Y is an NH group.

[0205] Implementation Scheme 19: A coating composition according to any one of the preceding embodiments, wherein the coating composition comprises 2-20% by volume, preferably 5-15% by volume, of the at least one silane compound SC, preferably a silane compound of general formula (I), based on the total volume of the coating composition in each case.

[0206] Implementation Scheme 20: The coating composition according to any one of the preceding embodiments, wherein the solvent S1 is selected from water, aliphatic and / or aromatic hydrocarbons, ketones, esters or mixtures thereof, preferably water or xylene and / or methoxypropanol or aliphatic hydrocarbons, as well as methoxypropyl acetate and butyl diethylene glycol acetate and diesters.

[0207] Implementation Scheme 21: A coating composition according to any one of the preceding embodiments, wherein the coating composition comprises 10-95% by weight, preferably 20-90% by weight, very preferably 25-60% by weight of the at least one solvent S1, in each case based on the total weight of the coating composition.

[0208] Implementation Scheme 22: The coating composition according to any one of the preceding embodiments, wherein the coating composition further comprises at least one crosslinking agent CL, the crosslinking agent CL preferably selected from amino resins, unblocked polyisocyanates, blocked polyisocyanates, polycarbodiimides, phenolic amine curing agents, polyaminoamide resins, melamine resins, resins containing carboxylic acid groups, β-hydroxyalkylamides, tris(alkoxycarbonylamino)triazine and mixtures thereof, very preferably phenolic amine curing agents and / or polyaminoamide resins and / or blocked or aromatic polyisocyanates and / or melamine resins.

[0209] Implementation Scheme 23: The coating composition according to Implementation Scheme 22, wherein the amine value of the at least one crosslinking agent CL is 100-300 mg KOH / g solid, preferably 140-200 mg KOH / g solid, as determined according to DIN 16945:1989-03.

[0210] Implementation Scheme 24: The coating composition according to Implementation Scheme 22 or 23, wherein the active hydrogen equivalent of the at least one crosslinking agent CL is 15-400 g / Eq. solids, preferably 150-300 g / Eq. solids.

[0211] Implementation Scheme 25: The coating composition according to Implementation Scheme 24, wherein the at least one crosslinking agent CL is selected from blocked polyisocyanates and / or melamine resins based on hexamethylene diisocyanate or isophorone diisocyanate.

[0212] Embodiment 26: The coating composition according to Embodiment 25, wherein the NCO content of the at least one blocked polyisocyanate is 4-12%, preferably 4-10%, more preferably 4.6-8.6%, based on the solid content in each case.

[0213] Implementation Scheme 27: The coating composition according to Implementation Scheme 25 or 26, wherein the melamine resin is selected from melamine resins etherified with methanol, ethanol, propanol and / or butanol, preferably melamine resins etherified with methanol, and contains an average of 0.05-3, preferably 0.07-2.5, and most preferably 0.08-2 imino groups.

[0214] Embodiment 28: A coating composition according to any one of Embodiments 22-27, wherein the coating composition comprises 1-30% by weight, preferably 5-20% by weight, and very preferably 10-15% by weight of the at least one crosslinking agent CL, in each case based on the total weight of the coating composition.

[0215] Implementation Scheme 29: The coating composition according to any one of the preceding embodiments, wherein the coating composition further comprises at least one curing catalyst.

[0216] Implementation Scheme 30: The coating composition according to Implementation Scheme 29, wherein the at least one curing catalyst is selected from functionalized phenols, tin (IV) compounds, bismuth compounds, blocked or unblocked sulfonic acid compounds and mixtures thereof, preferably 2,4,6-tris(dimethylaminomethyl)phenol or tin (IV) alkoxylates and / or blocked dinonylnaphthalene sulfonic acid.

[0217] Implementation Scheme 31: The coating composition according to Implementation Scheme 29 or 30, wherein the coating composition contains 0.05-5% by weight, preferably 0.1-3% by weight, very preferably 0.3-2.5% by weight of the at least one curing catalyst, in each case based on the total weight of the coating composition.

[0218] Implementation Scheme 32: A coating composition according to any one of the preceding embodiments, wherein the coating composition further comprises at least one pigment and / or filler.

[0219] Implementation Scheme 33: The coating composition according to Implementation Scheme 32, wherein the at least one pigment and / or filler is selected from (i) white pigments, such as titanium dioxide, zinc white, colored zinc oxide, zinc sulfide, and zinc barium white; (ii) black pigments, such as iron oxide black, iron manganese black, spinel black, and carbon black; (iii) colored pigments, such as ultramarine green, ultramarine blue, manganese blue, ultramarine violet, manganese violet, iron oxide red, molybdenum red, ultramarine red, iron oxide brown, mixed brown, spinel and corundum phase, iron oxide yellow, and bismuth vanadate; (iv) filler pigments, such as silica, silicon oxide, magnesium oxide, kaolin, quartz powder, aluminum oxide, aluminum hydroxide, natural mica, clay, natural and precipitated chalk, talc, barium sulfate, and barite; (v) corrosion-inhibiting pigments, such as calcium-modified silica pigments, zinc phosphate, aluminum phosphate, aluminum triphosphate, and magnesium silicate pigments; and (vi) mixtures thereof.

[0220] Implementation Scheme 34: The coating composition according to Implementation Scheme 32 or 33, wherein the coating composition comprises 10-70% by weight, preferably 20-60% by weight, very preferably 35-50% by weight of the at least one pigment and / or filler, in each case based on the total weight of the coating composition.

[0221] Implementation Scheme 35: A coating composition according to any one of Implementation Schemes 32-34, wherein the coating composition comprises a pigment to base ratio of 10:1 to 1:10, more preferably 6:1 to 1:6, even more preferably 5:1 to 1:2, and very preferably 7:3 or 2:1 to 1:2.

[0222] Implementation Scheme 36: A coating composition according to any one of the preceding embodiments, wherein the coating composition further comprises at least one coating additive selected from the group consisting of: (i) UV absorbers; (ii) light stabilizers, such as HALS compounds, benzotriazoles, or oxaloanilines; (iii) rheology modifiers, such as sagging control agents (urea crystallization modified resins), organic thickeners, and inorganic thickeners; (iv) free radical scavengers; (v) slip additives; (vi) polymerization inhibitors; (vii) defoamers; (viii) wetting agents; (ix) fluorinated compounds; (x) tackifiers; (xi) leveling agents; (xii) film-forming aids, such as cellulose derivatives; (xiii) flame retardants; and (xiv) mixtures thereof.

[0223] Implementation Scheme 37: A coating composition according to any one of the preceding embodiments, wherein the coating composition comprises 0% by weight of chromium and / or chromium-containing compounds, based on the weight of the coating composition.

[0224] Implementation Scheme 38: The coating composition according to any one of the preceding embodiments, wherein the coating composition has a Ford viscosity of 15-50 seconds, preferably 20-45 seconds, and most preferably 25-40 seconds in a DIN 4 cup at 20°C.

[0225] Implementation Scheme 39: A coating composition according to any one of Implementation Schemes 1-39, wherein the coating composition is heated at 23°C for 150 seconds. -1 The viscosity at the shear rate is 200-1000 mPa*s, preferably 500-800 mPa*s, as determined according to DIN ENISO 3219:1994-10 and DIN 53019-2:2002.

[0226] Implementation Scheme 40: A coating composition according to any one of Implementation Schemes 1 to 39, wherein the coating composition has a viscosity of 12-120 seconds / 4 mm, as determined according to DIN 53211-4.

[0227] Implementation Scheme 41: A coating composition according to any one of the preceding implementation schemes, wherein it is a primer composition, a first and second coat mixed primer composition, a filler coating composition, a conversion coating composition, an electrophoretic coating composition, or a dip coating composition.

[0228] Implementation Scheme 42: A method for preparing a coating composition according to any one of Implementation Schemes 1-41, comprising the following steps:

[0229] (a) Preparing a dispersion D of at least one graphene oxide (GO-M) containing at least one monovalent metal ion selected from lithium, potassium, and mixtures thereof in at least one solvent S2; and

[0230] (b) Add the dispersion D prepared in step (a) to a mixture comprising at least one base material B and / or at least one silane compound SC and at least one solvent S1.

[0231] Implementation Scheme 43: The method according to Implementation Scheme 42, wherein the dispersion D contains 0.05-5% by weight, preferably 1-4% by weight, and very preferably 1.5-3% by weight of the at least one graphene oxide (GO-M) containing at least one monovalent metal ion selected from lithium, potassium and mixtures thereof, based on the total weight of the dispersion in each case.

[0232] Implementation Scheme 44: The method according to Implementation Scheme 42 or 43, wherein the solvent S2 is selected from aliphatic and / or aromatic hydrocarbons, ketones, esters or mixtures thereof, preferably esters, and very preferably ethyl acetate.

[0233] Implementation Scheme 45: The method according to any one of Implementation Schemes 42-44, wherein the dispersion D contains 95-99.95% by weight, preferably 96-99% by weight, and very preferably 97-98.5% by weight of the at least one solvent S2, in each case based on the total weight of the dispersion.

[0234] Implementation Scheme 46: The method according to any one of Implementation Schemes 42-45, wherein the dispersion D is added in total amounts of 0.1-10% by weight, preferably 1-7% by weight, very preferably 2-4% by weight, based in each case on the total weight of the resulting coating composition.

[0235] Implementation Scheme 47: A method for forming at least one coating on a substrate (S), comprising the following steps:

[0236] (i) Applying the coating composition according to any one of claims 1-41 or the coating composition prepared by any one of claims 42-46 to the substrate (S);

[0237] (ii) A film is formed from the coating composition applied in step (i) through curing; and

[0238] (iii) Optionally, at least one other coating composition is applied to the coating formed in step (ii), and

[0239] The coating composition is cured.

[0240] Implementation Scheme 48: The method according to Implementation Scheme 47, wherein the substrate (S) is selected from metal substrates, metal substrates coated with conversion coatings, and mixtures thereof.

[0241] Implementation Scheme 49: The method according to Implementation Scheme 47 or 48, wherein the curing in step (ii) is carried out at a temperature of 20-25°C for 50-70 minutes, or at a temperature of 140-240°C for 20-60 seconds.

[0242] Implementation Scheme 50: The method according to any one of Implementation Schemes 47-49, wherein the dry film thickness obtained after step (ii) is 1-100 μm, preferably 2-90 μm, very preferably 55-75 μm or 3-30 μm.

[0243] Implementation Scheme 51: The method according to any one of Implementation Schemes 47-50, wherein (iii) at least one other coating is applied to the cured coating formed in step (ii), and the other coating is cured individually or simultaneously.

[0244] Implementation Scheme 52: The method according to Implementation Scheme 51, wherein the curing in step (iii) is carried out at a temperature of 50-70°C for 20-40 minutes, or at a temperature of 200-300°C for 10-30 seconds.

[0245] Implementation Scheme 53: The method according to Implementation Scheme 51 or 52, wherein the dry film thickness of the at least one other coating is 1-100 μm, preferably 1-90 μm, very preferably 50-60 μm or 1-5 μm.

[0246] Implementation Scheme 54: A coating or multilayer coating (MC) prepared by any one of Implementation Schemes 47-53.

[0247] Implementation Scheme 55: Use of at least one graphene oxide (GO-M) containing at least one monovalent metal ion selected from lithium, potassium and mixtures thereof in a composition to improve the corrosion resistance of the composition.

[0248] Implementation Scheme 56: The use according to Implementation Scheme 55, wherein the composition is a coating composition, preferably an organic coating composition.

[0249] Implementation Scheme 57: The use according to Implementation Scheme 55, wherein the composition is a sealant composition. Example

[0250] The invention will now be explained in more detail through the use of working embodiments, but the invention is by no means limited to these working embodiments. Furthermore, unless otherwise stated, the terms “parts,” “%,” and “ratio” in the embodiments refer to “parts by mass,” “% by mass,” and “mass ratio,” respectively.

[0251] 1. Measurement Method

[0252] 1.1 Raman spectroscopy

[0253] The structure of the prepared graphene oxide was determined by Raman spectroscopy using a RAM ARAMIS Raman spectrometer from the Horiba Jobin Yvon Lab. An excitation wavelength of 532 nm (green laser) was used, with an exposure time of 20 seconds, repeated three times. A 10% filter was used for the measurements.

[0254] 1.2 ICP-OES Analysis

[0255] The concentrations of monovalent or polyvalent metal ions present in graphene oxides were determined by ICP-OES using a Spectro Ciros CCD ICP-OES instrument and the Spectro Smart program Smart Analyzer. For different cations, the following spectral lines were used: Ca 2+ =183nm, K + =404nm, Li + =460nm, Mg 2+ =279nm, Na + =330nm, Zn 2+ =206nm, Fe 2+ =238nm, Al 3+ =396nm.

[0256] Therefore, the concentration of the corresponding metal ion in the filtrate obtained after filtering a graphene oxide containing at least one monovalent metal ion was determined by ICP-OES and compared with the concentration of the metal ion salt solution used to prepare the corresponding graphene oxide containing at least one monovalent metal ion. The difference between the concentration of the metal ion salt solution used to prepare the corresponding graphene oxide containing at least one monovalent metal ion and the concentration of the metal ion in the filtrate directly corresponds to the concentration of the metal ion present in the graphene oxide.

[0257] 1.3 Acidic salt spray test according to DIN EN ISO 9227AASS

[0258] The corrosion resistance of coatings on substrates was determined using an acidic salt spray test. An acidic salt spray test was performed on aluminum substrates, such as aluminum AA6014, according to DIN EN ISO 9227 (dated June 2017). The samples under study were placed in a chamber where a 5% salt solution, with a pH controlled between 3.1 and 3.3, was continuously sprayed at 35°C for 1008 hours. The spray deposited on the samples was covered by a corrosive film of the salt water.

[0259] Prior to acid salt spray testing according to DIN EN ISO 9227AASS, the coating on the studied sample was scribed down to the substrate using a blade to study the level of underfilm corrosion (damage) according to DIN EN ISO 4628-8 (dated: March 1, 2013), since the substrate corrodes along the scribing lines during the DIN EN ISO 9227AASS salt spray test. Due to the gradual process of corrosion, the coating is more or less damaged during the test. The degree of damage (in [mm]) is a measure of the coating's corrosion resistance. The average damage level described in the results below represents the average of the values ​​evaluated on two different plates, where each value is the average of the damage level at five measurement points on that plate.

[0260] 2. Preparation of lithium-ion-containing graphene oxide (GO@Li) and dispersion D

[0261] 2.1 Preparation of lithium-ion-containing graphene oxide (GO@Li)

[0262] Graphene oxide was prepared by electrochemical exfoliation of graphite in a two-electrode cell at room temperature using a Statron 3252.1 power supply: First, a graphite rod (10 cm long, 1 cm in diameter) and a platinum mesh electrode were placed in a 1 M NaOH solution for 10 minutes to pretreat the graphite. A voltage of 10 V was applied between the electrodes, with the positive electrode at the graphite (anode). The solution was then replaced with 0.5 M sulfuric acid, and electrolysis was performed for 1 hour at different applied voltages ranging from 1 to 10 V in 1 V increments. The received dark gray solution was then sonicated for 2 hours and filtered (0.45 μm pore size). The residue was collected, washed repeatedly with water, and dried at 60 °C.

[0263] The presence of graphene oxide and the absence of any graphite in the residue obtained by Raman spectroscopy determination as described in point 1.1 are generally considered to be in the G band (approximately 1595 cm⁻¹). -1 ) and D-band (approximately 1350cm) -1 Raman spectra with the same intensity are indicative of graphene oxides, while a higher G band than D band is indicative of graphene. Raman spectra obtained from the residue show G and D bands of almost equal intensity, thus characteristic of graphene oxides.

[0264] 0.1 g of the previously prepared graphene oxide was placed in a 50 ml test tube. 50 ml of a 0.1 M concentrated lithium salt solution was added to the tube, and the mixture was sonicated for 24 hours. After filtration (0.45 μm pore size) and drying at 60 °C, lithium-ion-containing graphene oxide was obtained. ICP-OES analysis as described in point 1.2 showed that the prepared graphene oxide contained approximately 1.8 mmol of lithium ions.

[0265] 2.2 Preparation of GO@Li-containing dispersion D

[0266] A dispersion D containing lithium-ion-containing graphene oxide in solvent S2 is prepared by dispersing the lithium-ion-containing graphene oxide (GO@Li) prepared in point 2.1 in an appropriate amount of ethyl acetate (the amounts of GO@Li and ethyl acetate used to prepare dispersion D are given in point 3 and Table 1).

[0267] 3. Preparation of conversion coating

[0268] The galvanized steel sheet was degreased at 60°C with a 60 g / L ENPREP 144 solution for 4 minutes, then rinsed with tap water for 2.5 minutes at room temperature, followed by rinsing with distilled water for 2.5 minutes. 2.7 ml of dispersion D (1 mg GO@Li / ml ethyl acetate) prepared according to point 2.2 was mixed with a silane compound SC (R) of general formula (I). 1 It is a C2 alkylene group, R 2 It is a C3 alkylene group, R a A coating composition was prepared by mixing a 10V% solution of an alkoxy group containing one carbon atom (x = 0, y = NH group) in a suitable organic solvent. A degreased galvanized steel sheet was treated with this coating composition at room temperature for 1 minute, and then dried at 80°C for 10 minutes to obtain a steel sheet with a conversion coating comprising at least one lithium-ion functionalized graphene oxide (GO@Li).

[0269] 4. Preparation of coating compositions F1 to F3

[0270] Coating compositions F1 to F3 are prepared by mixing the corresponding compositions F1-1 to F3-1 with hardener H and diluting the mixture with the commercially available product Glasurit 352-216 (available from BASF Coatings GmbH) described below.

[0271] 4.1 Preparation of base varnishes F1-1, F1-2 and F1-3

[0272] The base varnishes F1-1 to F3-1 are prepared according to the following general procedures:

[0273] First, premix positions 1-2 of Table 1, and add positions 2-4 while stirring at 1000-1500 rpm. After the addition is complete, continue stirring at 1500 rpm for 10 minutes. Then, add the remaining ingredients as described in Table 1, and stir the resulting mixture in a high-speed dissolving mixer for 20 minutes. Subsequently, disperse the mixture in a small laboratory mill for 1-1.5 hours until a Hegmann fineness of 22-23 μm is achieved. If necessary, add additional methoxypropanol after milling (see position 13 in Table 1).

[0274] Table 1: Components used to prepare base varnishes F1-1 to F3-1 (all amounts are given in weight % based on the total weight of the respective coating compositions)

[0275]

[0276] *This invention

[0277] 1)Example commercially available product: Epikote 834-X-80 (prepared from bisphenol A and epichlorohydrin, 80% solid xylene solution, EEW = 235-263 g / Eq., dynamic viscosity = 1 Pa*s (ASTM D445-06)) (supplied by Hexion),

[0278] 2) Example commercially available product: Beckopox EM 460 (prepared from bisphenol A, phenol, and bisphenol A diglycidyl ether, 60% solids isobutanol / xylene solution, dynamic viscosity = 800-1400 mPa*s (500 1 / s, 23°C, DIN EN ISO 3219)) (supplied by Allnex),

[0279] 3) Example commercially available product: Disperbyk 161 (30% solid methoxypropyl acetate / butyl acetate solution) (supplied by Byk Chemie GmbH),

[0280] 4) Example commercially available product: Schwersput EWO normal (oil grade = 11) (provided by SachtlebenMinerals),

[0281] 5) Example commercially available product: Lugenac 10M0 (oil grade = 48) (provided by Imerys PerformanceAdditives),

[0282] 6) A dispersion of 0.3 g graphene oxide in 15.91 g ethyl acetate.

[0283] 7) A dispersion of 0.3 g lithium-ion-containing graphene oxide (GO@Li) in 12.81 g ethyl acetate.

[0284] 8) Example commercially available product: Titan Rutil R-900-28WP (oil grade = 15), provided by Titanos.

[0285] 4.2 Hardener composition H

[0286] Curing agent H was prepared by mixing 49.6 g Cardolite NC 562 (an adducted phenolic amine curing agent, 65% solids, amine value = 185, active hydrogen equivalent = 174, supplied by Cardolite), 13.143 g Merginamid L190 / 70 (a reactive polyaminoamide resin, 70% solids, amine value = 155-185, active hydrogen equivalent = 340, supplied by HOBUM Oleochemicals GmbH), 1.2 g diethylenetriamine and 0.4 g Ancamine K54 (a curing catalyst, tris-2,4,6-dimethylaminomethylphenol, supplied by Evonik Industries AG).

[0287] 4.3 Coating compositions F1 to F3

[0288] Coating compositions F1 to F3 were prepared by mixing the corresponding base varnishes F1-1 to F1-3 with hardener H and diluting each mixture to a spray viscosity of 21s (DIN 4 cup, 20°C) with commercially available product Glaurit 352-216 (available from BASF Coatings GmbH).

[0289] Table 2: Composition of coating compositions F1 to F3

[0290]

[0291] *This invention

[0292] 4.4 Composition and properties of other coating compositions

[0293] 4.4.1 Primer Composition

[0294] Table 3: Coating compositions of the present invention as primers (amount in weight % based on the total weight of the coating composition)

[0295]

[0296] 1) Example commercially available product: URALAC SN 989S1F-60 (saturated polyester resin, 60%, in 30% solvent naphtha and 10% 1-methoxy-2-propyl acetate),

[0297] 2) Example commercially available product: Epikote 834-X-80 (an epoxy resin prepared from bisphenol A and epichlorohydrin, supplied as an 80% solid xylene solution),

[0298] 3)Examples of commercially available products: ALBERDINGK U 9000VP, 35% ig i.WA or ALBERDINGK 4820, 35% ig i.WA (polyurethane dispersion, OH functional).

[0299] 4) Example commercially available product: ALBERDINGK AC 2403, 47% ig i.WA (acrylic dispersion, OH functional, OH content 1.8%, based on solids).

[0300] 5) Example commercially available product: ALBERDINGK AC 2486, 48% ig i.WA (acrylic dispersion),

[0301] 6) Example commercially available product: Cymel 303, 98% ig (melamine resin HMM),

[0302] 7) Example commercially available products: VESTANADT EP-DS 1205, 42% ig i.WA (blocked isocyanate resin, aliphatic, NOC content: 4.6%, based on solids) or Vestanet EP-DS1076 (blocked isocyanate resin, aliphatic).

[0303] 8) Example commercially available product: Desmodur BL 3370 (a blocked aliphatic polyisocyanate based on hexamethylene diisocyanate, 70%)

[0304] 9) Example commercially available product: Titandioxid 2310,

[0305] 10) Example commercially available product: Aerosil 200

[0306] 11) Example commercially available product: Shieldex C 303 (calcium silicate),

[0307] 12) Example commercially available product: Heucophos ZPO (zinc phosphate),

[0308] 13) The quantity is based on the solid content of each component.

[0309] The coating compositions listed in Table 3 may additionally contain additives and fillers commonly used in primer compositions.

[0310] Preferred parameters for the above primer composition:

[0311] Solid content: 20 - 70 wt%

[0312] Ratio of pigment to base: 1.00:0.05 - 2.00

[0313] Viscosity: 1000 - 10000 mPa*s

[0314] Density: 1.050 - 1.400 g / cm 3

[0315] Prepare a cured coating using the primer composition:

[0316] Suitable substrates: Z (hot dip galvanized steel), ZE (electrolytically galvanized steel), ZM (zinc - magnesium coated steel)

[0317] Pretreatment: Granodine 1455 (pH value 2.0 - 2.5, coating weight < 8 mg Ti / m 2 )

[0318] Curing temperature (PMT, peak metal temperature): 200 - 250 °C

[0319] Residence time: 20 - 60 seconds

[0320] Preferred parameters for curing the primer layer:

[0321] Dry film thickness: 0.50 - 30.00 μm

[0322] Solid density: 1.05 - 2.00 g / cm 3

[0323] Elasticity: T - 0 to 1, Tesa tear, < T - 1 no crack (determined by T - bend)

[0324] Cross - linking (MEK - DH, according to EN 13523 - Part 11 resistance to methyl ethyl ketone): < 50 DH (after curing, if topcoat is used, > 100 MEK - DH)

[0325] Gloss: < 50 / 60° (mat - silk gloss)

[0326] 4.4.2 Water - soluble primer composition

[0327] Table 4: The coating composition of the present invention as a water - soluble primer (amounts are in wt% based on the total weight of the coating composition)

[0328]

[0329] 1)Example commercially available product: PHENODUR PW 165, 40WA (modified epoxy resin, OH functional, cationic stabilized).

[0330] 2) Example commercially available product: ALBERDINGK XP 27401, 38% ig i.WA (acrylic dispersion, OH functional, OH content 1.8%, based on solids),

[0331] 3) Examples of commercially available products: ALBERDINGK U 9000VP, 35% ig i.WA or ALBERDINGK 4820, 35% ig i.WA (polyurethane dispersion, OH functional).

[0332] 4) Example commercially available product: ALBERDINGK AC 2403, 47% ig i.WA (acrylic dispersion, OH functional, OH content 1.8%, based on solids).

[0333] 5) Example commercially available product: ALBERDINGK AC 2486, 48% ig i.WA (acrylic dispersion),

[0334] 6) Example commercially available product: Cymel 303, 98% ig (melamine resin HMM),

[0335] 7) Example commercially available products: VESTANADT EP-DS 1205, 42% ig i.WA (blocked isocyanate resin, aliphatic, NOC content: 4.6%, based on solids) or Vestanet EP-DS1076 (blocked isocyanate resin, aliphatic).

[0336] 8) Example commercially available product: BAHYDUR BL XP 2706, 40% ig i.WA (blocked isocyanate resin, aliphatic, NOC content: 8.6%, based on solids).

[0337] 9) Example commercially available product: Titandioxid 2310,

[0338] 10) Example commercially available product: Aerosil R 972,

[0339] 11) Example commercially available product: Shieldex C 303 (calcium silicate),

[0340] 12) Exemplary commercially available product: Heucophos ZPO (zinc phosphate),

[0341] 13) The amounts are based on the solids of the respective components.

[0342] The coating compositions listed in Table 4 may additionally contain additives and fillers commonly used in primer compositions.

[0343] Preferred parameters for the water-soluble primer composition:

[0344] Solid content: 10 - 50 wt%

[0345] Pigment to binder ratio: 1.00:0.05 - 2.00

[0346] Viscosity: 12 - 120 s / 4 mm (DIN 53211-4)

[0347] pH value: 1.50 - 9.00

[0348] Density: 1.050 - 1.400 g / cm 3

[0349] Prepare a cured coating using the primer composition:

[0350] Suitable substrates: Z, ZE, ZM

[0351] Optional pretreatment: Granodine 1455 (pH value 2.0 - 2.5, coating weight <8 mg Ti / m 2 )

[0352] Curing temperature (PMT): 140 - 250 °C

[0353] Dwell time: 5 - 60 s

[0354] Preferred parameters for curing the primer layer:

[0355] Dry film thickness: 0.20 - 20.00 µm

[0356] Solid density: 1.05 - 2.00 g / cm 3

[0357] Elasticity: T-0 to 1, Tesa tear, <T-1 no cracks (determined by T-bend)

[0358] Crosslinking (MEK-DH): <50 DH (after curing, if a topcoat is used, >100 MEK-DH)

[0359] Gloss: <50 / 60° (mat - silk gloss)

[0360] 4.4.3 Topcoat Composition

[0361] Table 5: Coating compositions of the present invention as topcoats (amount in weight % based on the total weight of the coating composition)

[0362]

[0363] 1) Example commercially available product: Dynapol LH 830, 60% ig (branched saturated copolyester, Mw = 4000 g / mol),

[0364] 2) Example commercially available product: Dynapol LH 538, 65% ig (branched saturated copolyester, Mw = 3000 g / mol),

[0365] 3) Example commercially available product: Dynapol UB 790, 60% ig (linear polyurethane resin, Mw = 3000-6000),

[0366] 4) Example commercially available product: Cymel 303, 98% ig (melamine resin HMM),

[0367] 5) Example commercially available product: Desmodur BL 3370, 70% ig (blocked aliphatic isocyanate),

[0368] 6) Example commercially available product: Vestanet EP-B 1481ND, 65% ig (isocyanate crosslinking agent, blocked with caprolactam),

[0369] 7) Example commercially available product: Titandioxid 2310,

[0370] 8) Example commercially available product: Aerosil R 972,

[0371] 9) Example commercially available product: Acematt 810,

[0372] 10) The quantity is based on the solid content of each component.

[0373] The coating compositions listed in Table 5 may additionally contain additives and fillers commonly used in primer compositions.

[0374] Preferred parameters for the topcoat composition:

[0375] Solid content: 50 - 70 wt%

[0376] Ratio of pigment to base: 1.00:0.50 - 1.50

[0377] Viscosity: 1000 - 10000 mPa*s

[0378] Density: 1.100 - 1.350 g / cm 3

[0379] Prepare a cured coating using the primer composition:

[0380] Suitable substrates: Z, ZE, ZM

[0381] Pretreatment: Granodine 1455 (pH value 2.0 - 2.5, coating weight < 8 mg Ti / m 2 )

[0382] Curing temperature (PMT): 200 - 260 °C

[0383] Residence time: 20 - 60 s

[0384] Preferred parameters for curing the primer layer:

[0385] Dry film thickness: 10.00 - 30.00 μm

[0386] Solid density: 1.30 - 1.80 g / cm 3

[0387] Elasticity: T - 0, Tesa tear, < T - 1 without cracks (determined by T - bend)

[0388] Crosslinking (MEK - DH): < 100 DH

[0389] Gloss: 20 - 90 / 60° (mat - glossy)

[0390] 4.4.4 Single - coat coating composition

[0391] Table 6: The coating composition of the present invention as a single - coat (amounts are in wt% based on the total weight of the coating composition)

[0392]

[0393]

[0394] 1) Exemplary commercially available product: Dynapol LH 830, 60% ig (branched saturated copolyester, Mw = 4000 g / mol),

[0395] 2)Example commercially available product: Dynapol LH 820, 55% g (branched saturated copolyester, Mw = 3000 g / mol),

[0396] 3) Example commercially available product: Dynapol L 205 (granules) (saturated polyester, Mw = 150,000),

[0397] 4) Example commercially available product: Cymel 303, 98% ig (melamine resin HMM),

[0398] 5) Example commercially available product: Desmodur BL 3370, 70% ig (blocked aliphatic isocyanate),

[0399] 6) Example commercially available product: Vestanet EP-B 1481ND, 65% ig (isocyanate crosslinking agent, blocked with caprolactam),

[0400] 7) Example commercially available product: Titandioxid 2310,

[0401] 8) Example commercially available product: Aerosil R 972,

[0402] 9) Example commercially available product: Acematt 810,

[0403] 10) Example commercially available product: Shieldex C 303 (calcium silicate),

[0404] 11) The quantity is based on the solid content of each component.

[0405] The coating compositions listed in Table 6 may additionally contain additives and fillers commonly used in primer compositions.

[0406] Preferred parameters for single-coat coating compositions:

[0407] Solid content: 40-70% by weight

[0408] Pigment to base ratio: 1.00:0.20-1.50

[0409] Viscosity: 1000-10000 mPa*s

[0410] Density: 1.100-1.400 g / cm³ 3

[0411] Prepare a cured coating using the primer composition:

[0412] Suitable substrates: Z, ZE, ZM

[0413] Pretreatment: Granodine 1455, pH value 2.0 - 2.5, coating weight < 8 mg Ti / m 2 )

[0414] Curing temperature (PMT): 200 - 260 °C

[0415] Residence time: 20 - 60 seconds

[0416] Preferred parameters for curing the primer layer:

[0417] Dry film thickness: 3.00 - 30.00 μm (applied directly to the pretreated substrate)

[0418] Solid density: 1.30 - 1.80 g / cm 3

[0419] Elasticity: T - 0, Tesa tear, < T - 1 no cracks (determined by T - bend)

[0420] Crosslinking (MEK - DH): < 100 DH

[0421] Gloss: 20 - 90 / 60° (mat - glossy)

[0422] 5. Preparation of multilayer coatings

[0423] The aluminum plate (AA 6014) is used directly after preparation. It is coated with the corresponding coating compositions F1 to F3 using a [spraying device] such that the dry film thickness after curing is 60 - 73 μm. After coating, the applied film is cured at 23 °C for 60 minutes.

[0424] Then, a topcoat composition is prepared by mixing the base varnish Glasurit Reihe 68 white, hardener 922 - 138, and rheology additive 352 - 216 (all products provided by BASF Coatings GmbH) in a ratio of 4:1:1. The topcoat composition is applied using a [spraying device] such that the dry film thickness after curing is 53 μm. After coating, the applied film is cured at 60 °C for 30 minutes.

[0425] 6. Results of acidic salt spray test

[0426] The acid salt spray test described in point 1.2 is carried out using the coated plate prepared according to point 5. After the test, the plate is cleaned with distilled water and the results obtained after removing rust with a knife after 1 hour and 24 hours are listed in Table 7. A difference of approximately 1 mm within the absolute range is technically difficult to evaluate and is therefore meaningless.

[0427] Table 7: Results of acidic salt spray test after 28 days (all values ​​are in [mm])

[0428]

[0429] 1) Aluminum plates coated with paint composition F1 and topcoat (free of graphene oxide or lithium-ion-containing graphene oxide),

[0430] 2) Aluminum plates (containing graphene oxide) coated with paint composition F2 and topcoat.

[0431] 3) An aluminum plate (containing lithium-ion-containing graphene oxide) coated with the coating composition F3 of the present invention and a topcoat.

[0432] As can be clearly seen from Table 7, the coating composition of the present invention containing graphene oxide functionalized with at least one lithium ion results in a multilayer coating (MC3) with improved corrosion resistance compared to a multilayer coating containing only graphene oxide (MC2) or a multilayer coating containing no graphene oxide (MC1). Therefore, introducing graphene oxide functionalized with at least one lithium ion into a primer or first-and-second-coat mixed primer composition significantly improves the corrosion resistance of the multilayer coating containing said primer or first-and-second-coat mixed primer layer.

Claims

1. A coating composition comprising: a) at least one graphene oxide containing a monovalent metal ion selected from lithium, wherein the graphene oxide containing a monovalent metal ion selected from lithium comprises at least one carboxylic acid group having at least one lithium counterion. b) at least one base material and / or at least one silane compound, said silane compound being selected from silane compounds comprising at least one primary amino group and at least one hydrolyzable alkoxy group; and c) At least one solvent.

2. The coating composition according to claim 1, wherein the coating composition comprises, in a total amount of 0.1 ppm to 5% by weight, at least one graphene oxide containing a monovalent metal ion selected from lithium.

3. The coating composition according to claim 1, wherein the coating composition comprises, in a total amount of 0.1 ppm to 1 wt%, at least one graphene oxide containing a monovalent metal ion selected from lithium.

4. The coating composition according to claim 1, wherein the coating composition comprises, in a total amount of 0.1-500 ppm, at least one graphene oxide containing a monovalent metal ion selected from lithium.

5. The coating composition according to claim 1, wherein the coating composition comprises, in a total amount of 0.3-50 ppm, at least one graphene oxide containing a monovalent metal ion selected from lithium.

6. The coating composition according to claim 1, wherein the coating composition comprises, in a total amount of 0.35-1 ppm, at least one graphene oxide containing a monovalent metal ion selected from lithium.

7. The coating composition according to any one of claims 1-6, wherein the at least one base material B is selected from (i) poly(meth)acrylate, (ii) polyurethane, (iii) linear or branched polyester or polyamide-modified polyester, (iv) polyether, (v) polyepoxide, (vi) phenoxy resin, (vii) copolymer of the polymer, and (vi) mixtures thereof.

8. The coating composition according to claim 7, wherein the at least one base material B is selected from (i) hydroxyl-functionalized and / or carboxylic acid-functionalized and / or amine-functionalized poly(meth)acrylates, (ii) hydroxyl-functionalized and / or carboxylic acid-functionalized and / or amine-functionalized polyurethanes, (iii) linear or branched polyester polyols, (iv) polyether polyols, (v) polyepoxides, (vi) phenoxy resins, (vii) copolymers of the polymers, and (vi) mixtures thereof.

9. The coating composition of claim 7, wherein the at least one base material is selected from polyepoxides, linear or branched polyesters and / or polyester-polyurethane copolymers.

10. The coating composition according to any one of claims 1-6, wherein the coating composition comprises at least one base material in a total amount of 1-40% by weight solids, based on the total amount of the coating composition in each case.

11. The coating composition of claim 10, wherein the coating composition comprises 15-20% by weight solids of the at least one polyepoxide or the at least one linear polyester, in each case based on the total amount of the coating composition.

12. The coating composition according to any one of claims 1-6, wherein the silane compound has the general formula (I): NH2-R 1 -Y-R 2 -Si(R a ) 3-x (R b ) x (I) in: R 1 R 2 Each is an alkylene group containing 1-10 carbon atoms; R a It is an alkoxy group containing 1-4 carbon atoms; R b It is an alkyl group containing 1-4 carbon atoms or an alkoxy group containing 1-4 carbon atoms; Y represents oxygen, sulfur, or NR. 3 Group, wherein R 3 It is hydrogen or an alkyl group containing 1-4 carbon atoms; and x is 0-1.

13. The coating composition according to any one of claims 1-6, wherein the coating composition comprises 2-20% by volume of the at least one silane compound in each case based on the total volume of the coating composition.

14. The coating composition according to claim 13, wherein the coating composition comprises 5-15% by volume of at least one silane compound of general formula (I) in each case based on the total volume of the coating composition.

15. The coating composition according to any one of claims 1-6, wherein the solvent is selected from water, aliphatic and / or aromatic hydrocarbons, ketones, esters or mixtures thereof.

16. The coating composition according to claim 15, wherein the solvent is selected from water or xylene and / or methoxypropanol or aliphatic hydrocarbons, as well as methoxypropyl acetate and butyl diethylene glycol acetate and diesters.

17. The coating composition according to any one of claims 1-6, wherein the coating composition comprises 10-95% by weight of the at least one solvent in each case based on the total weight of the coating composition.

18. The coating composition of claim 17, wherein the coating composition comprises 25-60% by weight of the at least one solvent in each case based on the total weight of the coating composition.

19. A method for preparing a coating composition according to any one of claims 1-18, comprising the following steps: (a) Prepare a dispersion of at least one graphene oxide containing a monovalent metal ion selected from lithium in at least one solvent S2; and (b) Add the dispersion prepared in step (a) to a mixture comprising at least one base material and / or at least one silane compound and at least one solvent.

20. The method of claim 19, wherein the dispersion D comprises 0.05-5% by weight of at least one graphene oxide containing a monovalent metal ion selected from lithium, based on the total weight of the dispersion in each case.

21. The method of claim 19, wherein the dispersion D comprises 1-4% by weight of at least one graphene oxide containing a monovalent metal ion selected from lithium, based on the total weight of the dispersion in each case.

22. The method of claim 19, wherein the dispersion D comprises 1.5-3% by weight of at least one graphene oxide containing a monovalent metal ion selected from lithium, based on the total weight of the dispersion in each case.

23. The method according to any one of claims 19-22, wherein the dispersion is added in a total amount of 0.1-10% by weight, based in each case on the total weight of the prepared coating composition.

24. The method of claim 23, wherein dispersion D is added in a total amount of 1-7% by weight, in each case based on the total weight of the prepared coating composition.

25. The method of claim 23, wherein dispersion D is added in a total amount of 2-4% by weight, based in each case on the total weight of the prepared coating composition.

26. A method for forming at least one coating on a substrate, comprising the steps of: (i) Applying the coating composition according to any one of claims 1-18 or the coating composition prepared by any one of claims 19-25 to a substrate; (ii) A film is formed from the coating composition applied in step (i); (iii) Optionally, at least one other coating composition is applied to the coating formed in step (ii) and the coating composition is cured.

27. A coating or multilayer coating prepared by the method of claim 26.

28. Use of a graphene oxide containing a monovalent metal ion selected from lithium in a coating composition according to any one of claims 1-18 to improve the corrosion resistance of the composition, wherein the graphene oxide containing a monovalent metal ion selected from lithium comprises at least one carboxylic acid group having at least one lithium counterion.

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