Method for coating a substrate having metal parts and plastic parts

Abstract

The invention relates to a process for coating a substrate with an aqueous primer coating material, comprising the steps of providing a substrate comprising at least two components, one component of the substrate being a metal, having a pre-coated metal surface area, and one component of the substrate being a plastic material, comprising one or more organic polymers and having an uncoated surface area comprising the one or more organic polymers, the one or more organic polymers consisting of carbon, hydrogen and optionally halogen atoms, or the one or more organic polymers containing carbonyl groups; and subsequently applying an aqueous primer coating material to the at least two surface areas to form a primer coating, the aqueous primer coating material containing 10 to 75 wt.-%, based on total binder solids, of one or more polymeric resins A, each of the polymeric resins having a hydroxyl number of 0 to 10 mg KOH / g; at least partially neutralized acid groups; and a polymeric backbone, which consists of hydrocarbon groups if the component of the substrate being a plastic material comprises an organic polymer according to b1, or an organic polymer according to b2, with the proviso that the carbonyl groups are part of amide moieties, or which comprises carbonyl groups if the component of the substrate being a plastic material comprises an organic polymer according to b2. The invention further relates to a substrate thus coated and to the use of the aqueous primer coating material for coating a substrate comprising the two components mentioned above.

Description

[0001] This invention relates to a method for coating a substrate with a water-based primer coating material, the substrate comprising pre-coated metal parts and uncoated plastic material parts. The invention further relates to the coated substrate and the use of the water-based primer coating material for coating a substrate comprising pre-coated metal parts and uncoated plastic material parts. Background Technology

[0002] Especially in the OEM (Original Equipment Manufacturer) vehicle coating industry, there are several challenges to overcome in the coating process. Typically, any coating process begins with the selection of a suitable substrate.

[0003] In vehicle coating, many of the parts to be coated are metal components with corrosion-prone surfaces. To increase the corrosion resistance of such parts (e.g., vehicle bodies), the bare metal substrate is thoroughly cleaned and converted with a coating such as zinc phosphate to obtain a first corrosion protection layer. Subsequently, it is common practice to apply an electrodeposited coating material, preferably by cathodic electrodeposition, to obtain a second corrosion protection layer. To obtain a complete multilayer structure, the electrodeposited metal substrate is coated with one or more primer layers, one or more base coat layers, and finally one or more clear coat layers. The customized primer coating material that adheres to the electrodeposited coating typically contains hydroxyl-containing resins as the main resin and generally does not adhere well to plastic surfaces, especially untreated plastic surfaces.

[0004] Other vehicle components are made of plastic materials containing one or more organic polymers. For these materials, corrosion resistance is not an issue, so they do not contain layers like the corrosion-protective coatings described above. Typically, coating begins with one or more primer coats, followed by one or more base coats, and finally one or more clear coats. However, for plastic substrates, there are other challenges to overcome, primarily related to the adhesion of the first or only primer coat to the plastic substrate. To increase primer adhesion, the OEM automotive industry utilizes physical surface treatment steps, such as flame treatment and / or plasma treatment, and first applies an adhesion promoter or special adhesion enhancer to the plastic material.

[0005] Therefore, it is common practice in OEM coating to use different primer coating materials on metal parts and plastic parts, each typically requiring different application and curing conditions. Since primer coating materials are also most often colored and thus impart color, obtaining primer formulations for both metal and plastic parts to have nearly identical colors is another challenge, as some color effects derived from the primer coating will affect the color of subsequent layers, even if the additional coating (such as a base coat) is also colored. If the metal and plastic parts of the substrate are to exhibit the same color appearance after a multi-layer coating process, it would be highly advantageous to use the same primer coating material on both the metal and plastic parts of the substrate to be coated.

[0006] This will also have the following advantages: those components of the substrate can be pre-assembled and coated with the exact same primer coating material in a single step under the same conditions on the same coating line, resulting in increased production compared to using two separate coating lines for metal and plastic components.

[0007] Furthermore, from an environmental perspective, the general-purpose primer coating material used in the method of coating the substrate should be water-based. Water-based paint compositions used only for plastic materials are disclosed, for example, in CN 111117380 A.

[0008] US 6,887,524 discloses a two-pack primer coating material for use on metal and plastic parts, which cures at temperatures below 100°C.

[0009] Therefore, a method is needed for coating substrates with a water-based universal primer coating material that adheres well to plastic substrates, even those untreated with flame and / or plasma treatment or pre-coated with an adhesion-promoting primer, and also adheres well to electroplated metal substrates. Furthermore, coating performed in a single step under identical conditions on the same production line not only ensures higher throughput but also provides a more uniform appearance and aesthetic harmony, as well as improved color, across all components of the substrate (metal and plastic parts), if applied with full cover thickness. To achieve these objectives, it is necessary to consider the different types of plastic materials that can be used in OEM coating processes, particularly their surface energies, which typically differ from those of electroplated metal substrates, and their thermal stability at the curing temperatures of the primer coating and / or multilayer coatings. Therefore, a general concept must be developed that allows for the customization of universal primer coating materials for application to electroplated metal surfaces (such as electroplated steel surfaces) and excellent adhesion to various specific plastic surfaces. Summary of the Invention

[0010] The above problems are overcome and these objectives are achieved by providing a method for coating a substrate with a water-based primer coating material, the method comprising the following steps:

[0011] i. Provide a base material comprising at least two components,

[0012] a. One component of the substrate is metal, having a pre-coated metal surface area, and

[0013] b. One component of the substrate is a plastic material, contains one or more organic polymers, and has an uncoated surface area containing the one or more organic polymers.

[0014] b1. The one or more organic polymers are composed of carbon, hydrogen, and optionally halogen atoms, or

[0015] b2. The one or more organic polymers contain a carbonyl group; and

[0016] ii. Applying a water-based primer coating material to the at least two surface areas to form a primer coating, the water-based primer coating material containing 15 to 75 wt.% of one or more polymeric resins A based on total binder solids, each of these polymeric resins having

[0017] a. Hydroxyl value of 0 to 10 mg KOH / g;

[0018] b. At least partially neutralized acid groups; and

[0019] c. Polymer backbone,

[0020] c1. If the component of the substrate as a plastic material contains an organic polymer according to b1, or an organic polymer according to b2—provided that these carbonyl groups are part of an amide moiety—then the polymer backbone consists of hydrocarbon groups, or

[0021] c2. If the component of the substrate that is a plastic material contains the organic polymer according to b2, then the polymer backbone contains carbonyl groups.

[0022] This method and its preferred embodiments are referred to below as "the method of the present invention" or "the method according to the present invention".

[0023] Another subject of the present invention is a coated substrate obtained by the method according to the invention, preferably a multilayer coated substrate obtained by the method according to the invention.

[0024] The substrates thus coated and their preferred embodiments are referred to herein as "coated substrates of the present invention" or "coated substrates according to the present invention".

[0025] Another subject of the present invention is the use of the water-based primer coating composition as described herein in vehicle coating, particularly automotive coating, for coating a substrate comprising at least two components as described herein.

[0026] This use and its preferred embodiments are referred to below as "use according to the invention" or "use according to the invention". Detailed Implementation

[0027] The method according to the invention will be further described below by way of preferred features and embodiments.

[0028] The method of the present invention

[0029] Step i.

[0030] In the first step of the invention, a substrate is provided, the substrate comprising at least two components, one component of the substrate being a metal having a pre-coated metal surface area, and the other component of the substrate being a plastic material comprising one or more organic polymers and having an uncoated surface area comprising the one or more organic polymers.

[0031] The substrate comprising the two components as defined above is preferably a pre-assembled component, at least one component being metal having a pre-coated metal surface area, and one component of the substrate being a plastic material comprising one or more organic polymers and having an uncoated surface area comprising the one or more organic polymers.

[0032] Metal components of the substrate

[0033] Components that include a pre-coated metal surface are metal components, and the term "metal" includes "alloys," which are preferably selected from the group consisting of bare steel, hot-dip or electroplated steel, cold-rolled steel, aluminum, and magnesium, or any of the aforementioned alloys.

[0034] These metal components of the substrate are not used as is in this invention, but are pre-coated.

[0035] As a pre-coating layer, at least one of a chemical pretreatment layer, such as a conversion coating, and an electro-coating layer is applied to the metal component prior to use in the method according to the invention. More preferably, an electro-coating layer is formed at least on the surface of the metal component, and even more preferably, a chemical pretreatment layer, such as a conversion coating, is first formed on the surface of the metal component, followed by the formation of the electro-coating layer. Therefore, it is particularly preferred that the pre-coated metal surface area includes a chemical pretreatment layer, such as a conversion coating, and an electrodeposited coating thereon.

[0036] The term "chemical pretreatment" is used according to EN ISO 4618:2006 (E / F / D) (term: 2.41 "chemical pretreatment", which represents any chemical process applied to a surface prior to the application of a coating material). According to this standard, treatments that fall under conversion treatment (such as chromate treatment and phosphate treatment) are considered chemical pretreatments and are therefore distinguished from the coating step in which a coating material (i.e., a coating composition) such as an electrodeposited coating material or other coating materials is applied.

[0037] Electrodeposited coatings are formed using electrodeposited coating materials, which are applied by dip coating with an aqueous coating composition, i.e., immersing a preferably chemically pretreated metal substrate in a conductive aqueous electrodeposited coating composition and applying a DC voltage between the substrate and a counter electrode. The electrodeposited coating composition is an anodic or cathodic electrodeposited coating composition, preferably a cathodic electrodeposited coating composition. The cathodic electrodeposited coating composition is preferably selected from epoxy-based and poly(meth)acrylate-based electrodeposited coating compositions. They are applied according to the paint manufacturer's instructions.

[0038] The component, which is a metal substrate, has a pre-coated metal surface area, which is therefore preferably an electrodeposited coating on the metal surface area, which is a cured layer.

[0039] Suitable examples of metal components of a substrate are substrates of any shape, such as vehicle bodies, especially motor vehicle bodies, such as car bodies, truck and tractor bodies, and their components, such as hoods, doors, fenders, bumpers and trim pieces.

[0040] Plastic material components of the substrate

[0041] Plastic material components of a substrate can be broadly classified as plastic materials comprising at least one of polar or nonpolar organic polymers. Plastic material components comprise organic polymers, or blends of organic polymers, and optionally at least one of pigments, fillers, and additives. Therefore, the term "plastic material component" includes polymers, polymer blends, and components such as pigments, fillers, and additives further blended with the foregoing.

[0042] Suitable nonpolar organic polymers for inclusion in plastic parts are so-called thermoplastic polyolefin elastomers (TPO).

[0043] Suitable polar organic polymers incorporated in plastic components contain carbonyl groups, which are preferably present in the urethane, carbonate, and amide moieties. The most suitable organic polymers are polycarbonate (PC) and polyamide.

[0044] Unlike existing methods, the plastic parts used in this invention are uncoated. They do not include any coating, such as an adhesion promoter or adhesion-promoting primer, prior to step ii., and they are preferably even untreated by flame or plasma treatment. The method of this invention eliminates the need for such treatments and coatings, and thus reduces the effort required to coat such substrates.

[0045] Suitable examples of plastic material components are, for example, bumpers, trim pieces, spoilers, tailgates, hoods, fuel tank caps, and rearview mirror housings.

[0046] Step ii.

[0047] In step ii., an aqueous primer coating material is applied to the at least two surface areas to form a primer coating.

[0048] Water-based primer coating materials

[0049] The water-based primer coating material is preferably a single-component (1K) primer coating material.

[0050] As used herein, the term "primer" is sometimes referred to in the literature as "primer surface agent" or "surface agent." Therefore, "primer coating material" is the same as "primer surface agent material" or "surface agent material."

[0051] "Single-package coating materials"—as defined in the textbook "Römpp Lexikon Lacke und Druckfarben [Römpp Encyclopedia of Coatings and Printing Inks]", Thieme, 1998—are coating compositions that, in contrast to the double-package coating materials described below, are produced and supplied in such a manner that they contain a base resin and a curing agent of one composition, without premature reaction between these components. The reaction is preferably induced by heating / baking or by reaction with moisture in the air. This definition applies to all single-package coating materials as described herein, whether they are primer coating materials, base coat coating materials, or varnish coating materials.

[0052] In contrast, “two-pack coating materials”—as defined in the textbook “Römpp Lexikon Lacke und Druckfarben [Römpp Encyclopedia of Coatings and Printing Inks]”, Thieme, 1998—are materials in which curing is achieved by mixing two components (the master batch “Stammlack” and the hardener “Harter”) in a specified mixing ratio. These components are not coating compositions on their own because they are not readily film-forming or do not form a durable film. This definition applies to all two-pack coating materials as described herein, whether they are primer coating materials, base coat coating materials, or clear coat coating materials.

[0053] As used herein, the term "aqueous" means that water is a component of the volatile components of the coating material. When used in combination with the coating material, another term for "aqueous" is "waterborn." Preferably, based on the volatile components of the coating material, the amount of water is at least 30 wt.-%, more preferably at least 40 wt.-%, and most preferably at least 50 wt.-%. The determination of the non-volatile portion, i.e., the total solids content, of the coating material is described below. The total volatile and non-volatile portions constitute 100 wt.-% of the coating material.

[0054] Polymer Resin A

[0055] The water-based primer coating material contains 10 to 75 wt.-%, preferably 15 to 65 wt.-%, and even more preferably 25 to 55 wt.-%, of one or more polymeric resins A as described above and below, based on total binder solids.

[0056] When total binder solids are mentioned herein, they refer to binder solids according to EN ISO 4618:2006 (E / F / D), which defines binder as the non-volatile portion of a coating material excluding pigments and fillers. Total binder solids are determined by first determining the total solids content. The total solids content is determined by drying a sample (approximately 1 g) of the coating material at 110°C for 30 min. The non-volatile portion is expressed as a weight percentage and is equal to the solids content. The difference from 100 wt.% is the volatile content. To obtain the total binder content, the amount of pigments and fillers used in the coating material, expressed as a weight percentage of the coating material, is subtracted from the total solids content expressed as a weight percentage. The determination of binder content and total solids content herein applies to any coating material, and also to the composition of the coating material prior to its incorporation into the corresponding coating material.

[0057] The common feature of polymer resin A is that it has a hydroxyl value of 0 to 10 mg KOH / g, more preferably 0 to 5 mg KOH / g, more preferably 0 to 3 mg KOH / g or 0 to 2 mg KOH / g. Particularly preferred is that polymer resin A has a hydroxyl value of 0 to 1 mg KOH / g. The hydroxyl value is determined according to ASTM standard test method E222-23 “Standard Test Methods for Hydroxyl Groups Using Acetic Anhydride Acetylation”.

[0058] Polymer resin A preferably has a weight-average molecular weight M in the range of 10,000 to 300,000 g / mol, more preferably in the range of 20,000 to 200,000 g / mol, even more preferably in the range of 30,000 to 150,000 g / mol, and most preferably in the range of 50,000 to 120,000 g / mol. w As determined by gel permeation chromatography and described in more detail in the experimental section of this invention.

[0059] Polymer resin A further comprises at least partially neutralized acid groups. These acid groups are preferably selected from carboxylic acid groups and / or carbonate groups, with carboxylic acid groups being more preferred. The term "at least partially neutralized acid groups" refers to polymer resin A as a substance containing acid groups. Some acid groups present in the polymer resin may remain in a protonated form, while other acid groups may be neutralized by one or more bases (such as alkali metal hydroxides or amines, preferably amines). This at least partial neutralization facilitates the dissolution or dispersion of polymer resin A in an aqueous medium.

[0060] Polymer resin A has a polymer backbone, which is the main chain of the polymer resin. According to the "Glossary of basic terms in polymer science" in IUPAC, Pure and Applied Chemistry 68, 2287-2311, the backbone is a straight chain, and all other chains (long or short, or both) can be considered its side chains. In cases where two or more chains can be equally considered as the backbone, the chain that produces the simplest representation of the molecule is chosen. According to the aforementioned IUPAC article, so-called pendant groups (or side-groups) are branches from the chain (neither oligomerizing nor polymerizing). Therefore, they—as used herein—are not part of the chain, but merely branches. Thus, the chlorinated copolymer of olefins and maleic acid has a polymer backbone as a hydrocarbon, while the chlorine atom and carboxylic acid group are considered not to belong to the polymer backbone, but are referred to below as side-groups (or pendant groups).

[0061] The selection of a suitable polymer resin A used in the method according to the invention depends on the component of the substrate containing the organic polymer in the respective surface area as a plastic material. It is not desirable to be bound by theory that either the hydroxyl value (preferably as low as possible, most preferably zero) or the presence of at least partially neutralized acid groups in polymer resin A alone makes the resin suitable as a specific plastic material containing the organic polymer in the respective surface area of ​​the substrate. Rather, it appears that the dispersion and diffusion interactions at the interface between the substrate and the water-based primer coating, in combination with other requirements, play a crucial role in good adhesion properties.

[0062] If the organic polymer on the component of the substrate that is a plastic material is precisely a nonpolar polymer, such as a polymer composed of carbon, hydrogen, and optionally halogen atoms, then polymer resin A is preferably obtained by polymerization of olefinically unsaturated monomers, resulting in the formation of a backbone composed of hydrocarbon groups. Most preferably, such polymers are selected from the group consisting of copolymers formed by polymerization of olefins and olefinically unsaturated dicarboxylic anhydrides, wherein halogenated olefins may also be used as olefins. In the final polymer resin A, the dicarboxylic anhydride is hydrolyzed in the form of acid groups, which are then at least partially neutralized again. If the organic polymer on the component of the substrate that is a plastic material is a polyamide, and therefore contains amide groups, then such polymer resin A is also suitable.

[0063] Examples of resin A suitable for plastic materials comprising one or more organic polymers (wherein the one or more organic polymers are composed of carbon, hydrogen and optionally halogen atoms) are selected from copolymers containing polymeric olefin groups (which are optionally partially halogenated) or composed of polymeric olefin groups, and having maleic anhydride groups as side groups, which are hydrolyzed and at least partially neutralized before use.

[0064] Suitable resins of the above types are commercially available, for example, under the trade names Hardlen NZ-1015, Hardlen EW-5303, Hardlen NZ-1004 (all from Toyobo Co., Ltd.), CP 310W, CP 347W, CP 349W (all from Eastman Corporation), and Superchlon S-4625.

[0065] If the organic polymer on the component of the substrate that is a plastic material is indeed a polar polymer, such as a polymer containing carbonyl groups, then it is preferable that polymer resin A also contains carbonyl groups as part of the polymer backbone. Such carbonyl groups (C=O) in the polymer backbone are preferably selected from urethane groups (such as NH-(C=O)-O groups), carbonate groups (such as O-(C=O)-O groups), and amide groups (such as -(C=O)-NH- groups).

[0066] A preferred example of such polymer resin A is, for example, the reaction product of an aliphatic polyisocyanate and a polycarbonate polyol. This resin contains urethane groups and carbonate groups, wherein a portion of the carbonate groups may be neutralized.

[0067] Polymer hydroxyl functional adhesive B

[0068] The water-based primer coating material preferably further contains one or more polymeric hydroxyl-functionalized resins B, different from polymeric resin A. Suitable polymeric hydroxyl-functionalized adhesives are, in principle, all polymeric polyhydroxyl-functionalized adhesives containing at least two hydroxyl groups and preferably selected from the group consisting of: polyurethane polyols, polyester polyols, polyether polyols, and poly(meth)acrylate polyols and / or copolymers of said polymers. Particularly preferably, at least one polymeric hydroxyl-functionalized resin B is selected from the group consisting of: polyurethane polyols, polyester polyols, poly(meth)acrylate polyols and / or copolymers of said polymers. The terms "(meth)acrylate" or "(meth)acrylic" represent both acrylate and methacrylate, and both acrylic and methacrylic. Preferably, any of the above-described polymeric hydroxyl-functionalized adhesives B further contains carboxyl groups, preferably at least partially neutralized carboxyl groups.

[0069] The one or more polymeric hydroxyl-functionalized resins B can be self-crosslinking, thus eliminating the need for additional crosslinking agent C as described below, or they can be crosslinked, i.e., react with crosslinking agent C. If one or more crosslinking agents C are required to cure the primer coating material, then the one or more polymeric hydroxyl-functionalized resins B are considered externally crosslinked compared to self-crosslinked polymeric hydroxyl-functionalized resins B. In principle, a mixture of self-crosslinked polymeric hydroxyl-functionalized resins B and externally crosslinked polymeric hydroxyl-functionalized resins B can be used in the primer coating material.

[0070] Polyester polyols are particularly preferred because they typically contain not only hydroxyl groups but also carboxyl groups, and both types of groups can react with, for example, amino plastic resins in the case of external crosslinking. Furthermore, the carboxyl groups (if at least partially neutralized) allow for improved dispersibility in water-based primer coating materials. Additional carboxyl groups can be introduced into polyester polyols by adding carboxylic anhydrides, partially esterifying the hydroxyl groups using polycarboxylic acids, or diene addition to unsaturated carboxylic acids.

[0071] Polyurethane polyols are preferably prepared from soft segments (polyesters, polyethers) with hydroxyl groups, diisocyanates, and hydroxycarboxylic acids (which subsequently form ion-supporting groups) and so-called chain extenders (which are primary or secondary polyamines or polyols). Depending on the molar ratio, molecules of different sizes can be prepared. If a certain excess of polyol is used, relatively low molecular weight polyurethanes are obtained, which are doped with terminal hydroxyl groups that can participate in the crosslinking reaction with amino plastic resins. In the same manner, the free isocyanate groups of the prepolymer can be reacted with a capping agent before the so-called chain extender. A small proportion of capping isocyanate groups can be obtained for crosslinking with the hydroxyl groups.

[0072] Most preferably, the polymer hydroxyl-functionalized resin B is selected from polyester polyols and polyurethane polyols.

[0073] The polymeric hydroxyl-functionalized binder B preferably has a hydroxyl value in the range of 1 to 200 mg KOH / g, more preferably 5 to 180 mg KOH / g, and even more preferably greater than 10 to 150 mg KOH / g (e.g., 11 to 150 mg KOH / g). The OH value can be calculated. The hydroxyl value is determined according to ASTM standard test method E222-23 "Standard Test Methods for Hydroxyl Groups Using Acetic Anhydride Acetylation".

[0074] The polymeric hydroxyl-functionalized binder B preferably has a weight-average molecular weight in the range of 2,000 to 200,000 g / mol, more preferably in the range of 5,000 to 150,000 g / mol, even more preferably in the range of 8,000 to 120,000 g / mol, and most preferably in the range of 10,000 to 100,000 g / mol, as determined by gel permeation chromatography and described in more detail in the experimental section of the invention.

[0075] Based on the total binder solids of the water-based primer coating material, the polymeric hydroxyl functional binder B is included in an amount ranging from 5 to 40 wt.-%, preferably 8 to 40 wt.-%, and more preferably 10 to 35 wt.-%.

[0076] If the polymeric hydroxyl-functionalized binder B is included in the aqueous primer coating material, the weight ratio of polymeric resin A to hydroxyl-functionalized binder B is in the range of 6:1 to 0.5:1. More preferably, it is in the range of 5.5:1 to 1:1, and even more preferably, it is in the range of 5:1 to 1:1.

[0077] Crosslinking agent C

[0078] The water-based primer coating material is preferably a one-component (1K) primer coating material. Among self-crosslinking 1K primer coating materials and externally crosslinking 1K primer coating materials, externally crosslinking primer coating materials are further preferred.

[0079] In water-based primer coating materials, amino plastic resins (also referred to as amino resins in the literature) are preferably used as external crosslinking agents C. These resins particularly include urea, melamine, and benzoguanamine (or glycourea) resins. Amino plastic resins preferably contain hydroxymethyl and / or ether groups, which can react with the hydroxyl and (if present) carboxyl groups of the polymeric hydroxyl-functionalized adhesive B.

[0080] Furthermore, as a substitute for or in addition to amino plastic resins, so-called terminally capped polyisocyanates can be used as the external crosslinking agent C. Terminally capped polyisocyanates include malonate-capped polyisocyanates and / or dimethylpyrazole-capped polyisocyanates. The polyisocyanate is preferably an aliphatic polyisocyanate, preferably based on an aliphatic diisocyanate, such as hexamethylene diisocyanate and / or isophorone diisocyanate. The polyisocyanate is preferably an oligomer of diisocyanate, such as diisocyanate, preferably an isocyanurate trimer of aliphatic diisocyanate, urethane, biuret, and urea diketone.

[0081] Based on the total binder solids of the waterborne primer coating material, crosslinking agent C is included in an amount ranging from 20 to 50 wt.%, preferably 25 to 45 wt.%, more preferably 30 to 40 wt.%. This range applies whether only amino plastic resins, only end-capped polyisocyanates, or a mixture of both are used. Preferably, only amino plastic resins are used as crosslinking agent C.

[0082] Paint Additive D

[0083] Waterborne primer coating materials preferably further contain typical coating additives D, such as light stabilizers, UV absorbers, thickeners, surfactants, catalysts such as those suitable for catalyzing crosslinking reactions, flame retardants, defoaming and degassing additives, conductivity modifiers, soluble dyes, wetting and dispersing agents, corrosion inhibitors, and rheology modifiers such as thickeners (also known as thickening agents). Examples of such thickeners are inorganic thickeners, such as metal silicates like layered silicates, and organic thickeners. Other typical additives for coatings are described, for example, in "Additives for Coatings," J. Bieleman, Wiley-VCH, 2001 reprint, pp. 248-253.

[0084] Based on the total binder solids of the water-based primer coating material, coating additive D is included in an amount ranging from 1 to 8 wt.-%, preferably 2 to 7 wt.-%, more preferably 2.5 to 6 wt.-%.

[0085] Pigments and / or fillers E

[0086] The water-based primer coating material preferably further contains one or more pigments and / or fillers E.

[0087] The term "pigment" is known to those skilled in the art, for example, from DIN 55943 (dated October 2001). In the sense of this invention, "pigment" preferably refers to components in powder or flake form that are substantially, preferably completely, insoluble in the surrounding application medium. Pigments are preferably colorants and / or substances that can be used as pigments due to their magnetic, electrical, and / or electromagnetic properties. Pigments differ from "fillers" in their refractive index; the refractive index of pigments is at least 1.7.

[0088] The concept of pigments encompasses both color pigments (the terms "pigment that imparts color" and "color pigment" are interchangeable) and effect pigments. Effect pigments are preferably those that impart optical effects, or both color and optical effects, more particularly optical effects. Therefore, the terms "optical effect and color pigments," "optical effect pigments," and "effect pigments" are interchangeable. Preferred examples of effect pigments are flake-like metallic effect pigments such as layered aluminum pigments, gold bronze, bronze oxide, and / or iron oxide-aluminum pigments; pearlescent pigments such as pearl essence, basic lead carbonate, bismuth oxychloride, and / or metal oxide-mica pigments; and / or other effect pigments such as layered graphite, layered iron oxide, multilayer effect pigments composed of PVD films, and / or liquid crystal polymer pigments.

[0089] In principle, the use of effect pigments is possible. However, since the paint is a primer coating material, incorporating effect pigments is not preferred. Therefore, it is preferable that the primer coating material does not contain effect pigments.

[0090] Therefore, colored pigments are preferably used as pigments. Organic and / or inorganic pigments can be used as colored pigments. Inorganic colored pigments are preferred. Particularly preferred colored pigments used are white pigments, colored pigments, and / or black pigments. Examples of white pigments are titanium dioxide, zinc white, zinc sulfide, and zinc barium white. Examples of black pigments are carbon black, iron-manganese black, and spinel black. Examples of colored pigments are chromium oxide, hydrated chromium oxide green, cobalt green, ultramarine green, cobalt blue, ultramarine blue, manganese blue, ultramarine violet, cobalt-manganese violet, iron oxide red, cadmium sulfide selenide, molybdenum chrome red, ultramarine red, iron oxide brown, mixed brown, spinel phase and corundum phase, and chrome orange, iron oxide yellow, nickel titanium yellow, chrome titanium yellow, cadmium sulfide, zinc cadmium sulfide, chrome yellow, and bismuth vanadate. Examples of suitable organic pigments for imparting color include monoazo pigments, diazo pigments, anthraquinone pigments, benzimidazole pigments, quinacridone pigments, quinoline phthaloyl ketone pigments, pyrrolopyrrole dione pigments, dioxazine pigments, indanthrone pigments, isoindoline pigments, isoindoline ketone pigments, methylimine pigments, indigo sulfide pigments, metal complex pigments, perinone pigments, perylene pigments, phthalocyanine pigments, or aniline black.

[0091] Based on the total weight of the water-based primer coating material, pigments and / or fillers E are included in an amount ranging from 5 to 40 wt.-%, preferably 10 to 35 wt.-%, more preferably 15 to 30 wt.-%.

[0092] Organic solvent F

[0093] The water-based primer coating material preferably further contains one or more solvents F selected from the group consisting of: water-soluble and / or water-dispersible organic solvents, such as alcohols, like 2-ethylhexanol; glycol ethers, such as ethylene glycol monobutyl ether, diethylene glycol butyl ether and dipropylene glycol methyl ether; glycol ether esters, such as propylene glycol monomethyl ether acetate, ethylene glycol butyl ether acetate, 3-methoxy-n-butyl acetate; and lactams, such as N-methylpyrrolidone (NMP); and mixtures thereof.

[0094] Based on the total weight of the water-based primer coating material, the organic solvent F is included in an amount ranging from 5 to 25 wt.-%, preferably 8 to 20 wt.-%, and more preferably 10 to 17 wt.-%.

[0095] Water-based primer coating materials are preferably applied to the substrate by any conventional application method. Representative examples of application methods include, but are not limited to, spraying, scraping, spreading, pouring, dipping, dripping, or rolling. With this application, the substrate to be coated can be stationary, while the application unit or equipment is moving. Alternatively, the substrate to be coated, more particularly, can be moving, where the application unit is stationary or appropriately moving relative to the substrate. Preferred application methods include air spraying, airless spraying, high-speed rotation, electrostatic spraying, alone or in combination with thermal spraying such as hot air spraying.

[0096] Step iii.

[0097] To obtain a multi-layered coating as typically used in OEM vehicle coatings, particularly OEM automotive coatings, step ii. is followed by steps iii. and iv., namely, applying one or more base coat materials onto the base coat to form one or more base coats, and subsequently applying one or more clear coat materials, and then finally curing all the layers applied in steps ii., iii. and iv.

[0098] After step ii. and before applying the one or more base coat materials, the primer coating is preferably at least partially dried (i.e., flash-dried) at a temperature in the range of 15°C to 35°C, more preferably 20°C to 30°C. Curing of the primer coating is preferably avoided at this stage.

[0099] The terms "basecoat material" (i.e., "basecoat material") and correspondingly "basecoat film" are known to those skilled in the art and are preferably used as names for intermediate coatings that impart color and / or effects in general industrial coatings, particularly automotive (OEM) coatings. Usable basecoat materials are commercially available basecoat materials, such as solvent-based or water-based basecoats, with water-based basecoat materials being preferred. Basecoat materials are preferably selected from 1K basecoat materials (also referred to as "single-component basecoat material" or "single-package basecoat material") and 2K basecoat materials (also referred to as "two-component basecoat material" or "two-package basecoat material").

[0100] In the context of this invention, a preferred base coat material is a base coat material comprising a polymer that is curable by physical, thermal, or both thermal and photochemical radiation as a binder.

[0101] In the context of this invention, the term "physical curing" means the formation of a film by causing solvent to be lost from a polymer solution or polymer dispersion. Typically, this curing does not require a crosslinking agent.

[0102] In the context of this invention, the term "thermosetting" refers to thermally initiated crosslinking of the coating film, wherein a separate crosslinking agent or an additional self-crosslinking adhesive is used in the parent coating material. The crosslinking agent contains reactive functional groups complementary to the reactive functional groups present in the adhesive. This is commonly referred to as external crosslinking by those skilled in the art. In cases where complementary reactive functional groups or self-reactive functional groups—i.e., groups that react with the same kind of groups—are already present in the adhesive molecule, the present adhesive is self-crosslinked. Examples of suitable complementary reactive functional groups and self-reactive functional groups are known from German patent application DE 199 30 665 A1, page 7, line 28 to page 9, line 24.

[0103] For the purposes of this invention, photochemical radiation refers to electromagnetic radiation, such as near-infrared (NIR) radiation, UV radiation, more particularly UV radiation, and particulate radiation, such as electron radiation. Curing by UV radiation is typically initiated by free radical or cationic photoinitiators. The term "dual curing" is also used when thermal curing and photochemical light curing are employed in synergistic ways.

[0104] In this invention, both physically curable and heat-curable base coat materials are preferred. In the case of heat-curable base coat materials, a certain proportion of physical curing is always present. However, for reasons of ease of understanding, these coating materials are referred to as heat-curable.

[0105] Preferred thermosetting base coat materials include at least one of polyurethane resin, polyurethane-poly(meth)acrylate resin, polyester resin, and poly(meth)acrylate resin as a binder, and an amino plastic resin or a capped or uncapped polyisocyanate, preferably an amino plastic resin, as a crosslinking agent with complementary reactive groups. Melamine resin is preferred among the amino plastic resins.

[0106] Paint additives D, pigments E and / or fillers E, and organic solvents F (all as described for water-based primer coating compositions) may also be included in the base coat material, preferably a water-based base coat material. However, unlike the primer coating material, effect pigments are preferably included in the base coat material.

[0107] The base coat material is preferably applied to the uncured (not yet fully cured) base coat by any of the methods described for step ii.

[0108] After step iii, the one or more base coats are preferably at least partially dried (flashed) at a temperature in the range of 50°C to 80°C, more preferably 55°C to 75°C. Curing, especially complete curing, of the one or more base coats should be avoided at this stage.

[0109] Step iv.

[0110] One or more varnish coating materials are applied to an uncured (not fully) cured base coat material to form one or more varnish coatings.

[0111] As is known, a varnish coating material is a coating material that, after application and curing, forms a transparent coating (varnish) with protective and / or decorative properties. Protective properties refer to, for example, scratch resistance and weather resistance, and more particularly, UV resistance. An example of a decorative property is good gloss. The varnish materials to be used are those commonly used in the field of plastic coating, and their selection and uses are known to those skilled in the art (in this regard, see also Römpp-Lexikon Lackeund Druckfarben [Römpp Encyclopedia of Coatings and Printing Inks], Georg Thieme Verlag, Stuttgart, New York, 1998, p. 325).

[0112] Any conventional varnish coating material, such as liquid or solid varnish coating materials, can be applied. Preferably, the varnish coating material is a liquid varnish coating material selected from the group consisting of: 1K solvent-based varnish coating materials, 2K varnish coating materials, and 1K water-based varnish coating materials. However, powder varnish coating materials can also be used.

[0113] In single-component (1K) varnish coating materials, those comprising one or more poly(meth)acrylate polyols and one or more amino plastic crosslinking agents are preferred, these amino plastic crosslinking agents being preferably selected from the group consisting of melamine resins, more preferably alkoxylated melamine resins. Preferably, such systems are cured at 130°C to 150°C for 12 to 20 minutes.

[0114] Another group of one-component (1K) varnish coating materials is the so-called acrylate amino-plastic silane varnish coating material, which contains one or more poly(meth)acrylate polyols that additionally contain hydrolyzable silane groups, which hydrolyze during the baking step to form silanol groups. The silanol groups condense to establish additional crosslinks via the siloxane structure. It further contains one or more amino-plastic crosslinking agents, which are preferably selected from the group consisting of melamine resins that react with hydroxyl groups at the one or more poly(meth)acrylate polyols, more preferably alkoxylated melamine resins.

[0115] Another group of one-component (1K) varnish coating materials comprises one or more primary carbamate functional polymers and one or more amino plastic crosslinking agents, which are preferably selected from the group consisting of melamine resins, more preferably alkoxylated melamine resins.

[0116] Another group of one-component (1K) varnish coating materials comprises one or more hydroxyl-functionalized polymers, preferably one or more poly(meth)acrylate polyols, and one or more end-capped polyisocyanates, such as malonate-terminated polyisocyanates and / or dimethylpyrazole-terminated polyisocyanates. The polyisocyanate is preferably an aliphatic polyisocyanate, preferably based on an aliphatic diisocyanate, such as hexamethylene diisocyanate and / or isophorone diisocyanate. The polyisocyanate is preferably an oligomer of diisocyanate, such as diisocyanate, preferably an isocyanurate trimer of aliphatic diisocyanate, urethane, biuret, and urea diketone.

[0117] Another group of varnish coating material systems is the so-called epoxy acid varnish coating system, which contains one or more poly(meth)acrylates containing glycidyl groups and one or more polycarboxylic acids. During the curing reaction of both, a β-hydroxy polyester is formed. These systems can be formulated as one-component (1K) or two-component (2K) systems.

[0118] Typical two-component clear coat materials comprise one or more polymeric polyols, preferably selected from polyurethane polyols, polyester polyols, and poly(meth)acrylate polyols, and one or more polyisocyanates. The polyisocyanate is preferably an aliphatic polyisocyanate, preferably based on an aliphatic diisocyanate, such as hexamethylene diisocyanate and / or isophorone diisocyanate. The polyisocyanate is preferably an oligomer of a diisocyanate, such as a diisocyanate, preferably an isocyanurate trimer of an aliphatic diisocyanate, urethane, biuret, and urea diketone.

[0119] One-component (1K) waterborne varnish coating materials can also be used. These varnish coating materials preferably contain one or more polyester-poly(meth)acrylate polyols and one or more end-capped polyisocyanates and / or amino plastic resins, preferably melamine resins, and most preferably alkoxylated melamine resins.

[0120] The general technique for applying the varnish coating material is consistent with those described above for step ii., and has the same preferences. The varnish coating material is preferably applied to an uncured (not yet fully) cured base coat. The varnish material is applied at a conventional and known film thickness, for example, a wet film thickness of 50 to 250 micrometers, preferably 100 to 180 micrometers. The resulting dry film thickness after curing is then, for example, in the range of 15 to 80 micrometers, more particularly 25 to 50 micrometers.

[0121] Subsequently, in step v., the layers obtained in steps ii., iii. and iv. are co-cured at a temperature depending on the chemical properties of the coating materials that form these layers, but this temperature is typically in the range of 120°C to 160°C, more preferably 130°C to 150°C.

[0122] Dry film thickness

[0123] The dry film thickness was determined according to ISO 2808:2019 Method 7C.

[0124] The dry film thickness of the primer coating is preferably in the range of 5 to 20 µm, more preferably in the range of 8 to 16 µm, and most preferably in the range of 10 to 14 µm.

[0125] The dry film thickness of the one or more basecoat coatings is preferably in the range of 7 to 25 µm, more preferably in the range of 10 to 20 µm, and most preferably in the range of 12 to 18 µm. It is possible to apply multiple basecoat layers; however, wet-to-wet application of the same basecoat is precisely understood herein as applying a basecoat coating material in several spray coats. Multiple basecoat coating materials are only considered to be applied when different basecoats are applied. As used herein, the term "dry film thickness" refers to the total dry film thickness of all basecoat coatings, regardless of the number of basecoat coatings. This also applies to the dry film thickness of the one or more clear coats.

[0126] The dry film thickness of the one or more varnish coatings is preferably in the range of 35 to 70 µm, more preferably in the range of 40 to 65 µm, and most preferably in the range of 45 to 60 µm.

[0127] The coated substrate of the present invention

[0128] Another object of the present invention is a coated substrate obtainable by the method according to the invention. Any preferred features and embodiments disclosed with respect to the method of the invention also apply to the coated substrate of the invention.

[0129] Uses of the water-based primer coating composition of the present invention

[0130] Another object of the present invention is the use of the waterborne primer coating composition as defined above in vehicle coating, preferably automotive OEM coating, in coating a substrate comprising at least two components as defined above.

[0131] Any preferred features and embodiments disclosed regarding the method of the present invention are also applicable to the coated substrates of the present invention.

[0132] The invention will be further illustrated below with examples of working practices. Experimental Section

[0133] Parameter determination and testing methods

[0134] Number average molecular weight M n and weight average molecular weight M w

[0135] Molecular weights were determined by gel permeation chromatography (GPC). To determine polymer molecular weights by GPC, completely dissolved molecules of the polymer sample were fractionated on a porous column stationary phase. A 0.1 mol / L acetic acid solution in tetrahydrofuran (THF) was used as the elution solvent. The stationary phase was a combination of Waters Styragel HR 5, HR 4, HR 3, and HR 2 columns. Five mg of sample was added to 1.5 mL of elution solvent and filtered through a 0.5 µm filter. After filtration, 100 µL of the polymer sample solution was injected into the column at a flow rate of 1.0 mL / min. Separation was based on the size of the polymer coils formed in the elution solvent. Smaller molecules diffused more frequently into the pores of the column material and were therefore delayed more than larger molecules. Consequently, larger molecules eluted earlier than smaller molecules. The molecular weight distribution, mean, and polydispersity M of the polymer samples were determined. w / M n The calculation was performed using chromatography software that utilized calibration curves generated by an EasyValid validation kit, which included a range of unbranched polystyrene standards of varying molecular weights available from Polymer Standards Service.

[0136] Initial cross-cut adhesion

[0137] The initial cross-cut adhesion was determined according to ISO 2409 (Paints and Varnishes - Cross-Cut Test).

[0138] Adhesion after wetting

[0139] The cross-cut adhesion after wetting was determined according to ISO 6270-2 (Paints and Varnishes - Determination of Resistance to Humidity - Part 2: Condensation (In-Cabinet Exposure with Heated Water Reservoir) and ISO 2409 (Paints and Varnishes - Cross-Cut Test).

[0140] Steam jet adhesion

[0141] Steam jet adhesion was determined according to ISO 16925 (Paints and Varnishes - Determination of the Resistance of Coatings to Pressure Water-Jetting, Method B). The numerical ratings from 0 to 5 correspond to the degree of delamination (0 for no delamination and 5 for severe delamination). The letter classifications are given based on the appearance and characteristics of the delamination areas (a: delamination along the scribing line, b: circular delamination area, c: delamination perpendicular to the scribing line).

[0142] Windshield adhesive strength

[0143] To evaluate windshield adhesive adhesion, two polyurethane strips (BetaSeal 15709) were first applied to the surface of a coated test panel (cold-rolled steel) using a cordless electric caulking gun. The polyurethane strips were then cured for 5 days at 23°C in a climate-controlled environment with 65% humidity. At this point, the coated substrate was removed, and one polyurethane strip was pulled under constant pressure while simultaneously being cut with a razor blade to determine whether separation occurred from the substrate (adhesion failure) or from within the strip (cohesive failure). The polyurethane strip was then examined to determine the percentage of sealant adhesion cracking from the coating compared to sealant cohesive cracking. A "pass" was considered to indicate a sealant cohesive failure (CF) >95%.

[0144] Subsequently, according to ISO 6270-2 (Determination of Resistance to Humidity - Part 2: Condensation (In-Cabinet Exposure with Heated Water Reservoir)), the test panels were subjected to a high humidity environment for 14 days. The test panels were then subjected to a 24-hour readjustment period, followed by the same polyurethane strip cutting and evaluation procedure.

[0145] Preparation of coated substrate

[0146] Cold-rolled steel test plate

[0147] A 10 cm × 30 cm cold-rolled steel test plate was used as the substrate. The plate was pretreated with Bondrite® 958 zinc phosphate chemical pretreatment and rinsed with Parcolene® 90 post-rinse agent, both available from Henkel. The plate was then electrocoated with 18 to 20 µm layers of BASF Cathoguard® 800 electrocoating and baked at 177°C for 20 minutes.

[0148] The test panels were sprayed with a 13 µm to 18 µm layer of either the comparative primer C1 or the primers E1 and E2 of the present invention (the primer compositions are shown in Table 1).

[0149] After applying the appropriate primer coating material, the test panels underwent 5 minutes of ambient flash evaporation. Subsequently, BASF E278KU105 (black water-based primer) was applied in two coats to form a layer with a dry layer thickness of 10 µm to 15 µm. After applying the primer, the test panels underwent 5 minutes of ambient flash evaporation and 6 minutes of heated flash evaporation at 60°C. Subsequently, a solvent-based two-component clear coat coating material was applied to form a layer with a dry layer thickness of 46 to 51 µm (applied in two coats). After applying the clear coat, the test panels underwent 10 minutes of ambient flash evaporation and 20 minutes of baking at 141°C.

[0150] Plastic test plate

[0151] To coat plastic test panels according to the method of the present invention, untreated and uncoated (received as is) plastic test panels are used, following the same coating procedure as described above with primer, base coat, and clear coat. For plastics coated using comparative primer C1, the plastic test panels are first coated with a 2.5 to 5 µm layer of BASF U339AW073 (aqueous adhesion promoter). Polycarbonate is used as the polar plastic material in the examples, and thermoplastic polyolefin is used as the non-polar plastic material in the examples.

[0152] The plastic test plates were coated together with the metal test plates and then sent for testing.

[0153] Table 1 provides primer compositions prepared and applied to substrates.

[0154] Table 1

[0155]

[0156] result

[0157] Initial cross-cut adhesion, cross-cut adhesion after wetting, steam jet adhesion, and windshield adhesive adhesion.

[0158] The initial cross-cut adhesion, wet cross-cut adhesion, steam jet adhesion, and windshield adhesive adhesion of the coated substrate in Example 1 were evaluated. The test results are shown in Table 2.

[0159] Table 2 summarizes the test results for the initial cross-cut adhesion, steam jet adhesion, windshield adhesive adhesion, and wet cross-cut adhesion of the coated substrate from Example 1.

[0160] Table 2

[0161]

[0162] Non-polar plastic materials = thermoplastic polyolefins (TPO)

[0163] Polar plastic material = polycarbonate (PC)

[0164] 1 Contains adhesion promoter

[0165] 2 nd = Undetermined

[0166] 3 na = Not applicable

[0167] 4 The value represents the percentage of cohesive failure.

[0168] As indicated, the primer coating materials disclosed herein are suitable for promoting adhesion on both metallic and plastic substrates. Primer E1 in multilayer coating MLC-E1 is suitable for promoting adhesion on both metallic and polar plastic substrates, and primer E2 in multilayer coating MLC-E2 is suitable for promoting adhesion on both metallic and non-polar plastic substrates. Surprisingly, the primer compositions of the present invention are suitable for improving adhesion to both metallic and non-metallic coated substrates while utilizing a large percentage of non-functional resin components in the formulation. This is even achieved on plastic materials that are obtained completely untreated, without flame treatment, plasma treatment, or even pre-coating with adhesion promoters or adhesion-promoting primers.

[0169] Table 3

[0170]

[0171] 1 Color data was acquired using a BYKmac-I multi-angle spectrophotometer.

[0172] 2 The value was measured at a 45° angle.

[0173] As indicated, the primer coating material disclosed herein allows for the simultaneous coating of two substrates on a single coating line. This ability to coat plastic and metal substrates under identical conditions in a single step on the same production line improves color harmony between substrates when applied at full cover thickness, as demonstrated in Table 3.

Claims

1. A method for coating a substrate with a water-based primer coating material, the method comprising the following steps: i. Provide a base material comprising at least two components, a. One component of the substrate is metal, having a pre-coated metal surface area, and b. One component of the substrate is a plastic material, contains one or more organic polymers, and has an uncoated surface area containing the one or more organic polymers. b1. The one or more organic polymers are composed of carbon, hydrogen, and optionally halogen atoms, or b2. The one or more organic polymers contain a carbonyl group; and ii. Applying a water-based primer coating material to the at least two surface areas to form a primer coating, the water-based primer coating material containing 15 to 75 wt.% of one or more polymeric resins A based on total binder solids, each of these polymeric resins having a. Hydroxyl value of 0 to 10 mg KOH / g; b. At least partially neutralized acid groups; and c. Polymer backbone, c1. If the component of the substrate as a plastic material contains an organic polymer according to b1, or an organic polymer according to b2—provided that these carbonyl groups are part of an amide moiety—then the polymer backbone consists of hydrocarbon groups, or c2. If the component of the substrate that is a plastic material contains the organic polymer according to b2, then the polymer backbone contains carbonyl groups.

2. The method for coating a substrate according to claim 1, wherein, The uncoated surface area containing the one or more organic polymers is neither flame-treated nor plasma-treated.

3. The method for coating a substrate according to claim 1 or 2, wherein, The pre-coated metal surface area is a metal surface area pre-coated with a cured electrocoating layer and optionally a conversion coating layer under the cured electrocoating layer.

4. The method for coating a substrate according to any one or more of the preceding claims, wherein, b.1 One or more organic polymers composed of carbon, hydrogen, and optionally halogens are selected from polyolefins and halogenated polyolefins; and b2. One or more organic polymers containing carbonyl groups are selected from the group consisting of polycarbonates and polyamides.

5. The method for coating a substrate according to any one or more of the preceding claims, wherein, The polymer backbone of one or more polymer resins A contained in the water-based primer coating material c1 is the polymer backbone of an (unsaturated dicarboxylic acid) / (olefin) copolymer, and c2 is a polymer backbone containing carbonyl groups that are present in at least one or more of the following portions: urethane groups and carbonate groups.

6. The method for coating a substrate according to any one or more of the preceding claims, wherein, The at least partially neutralized acid groups of the one or more polymer resins contained in the water-based primer coating material are at least partially neutralized carboxylic acid groups and / or at least partially neutralized carbonate groups.

7. The method for coating a substrate according to any one or more of the preceding claims, wherein, This water-based primer coating material is a single-package coating material.

8. The method for coating a substrate according to any one or more of the preceding claims, wherein, This water-based primer coating material further contains the following components: B. One or more polymeric hydroxyl-functionalized adhesives B, selected from polyurethane polyols, polyester polyols, polyether polyols, poly(meth)acrylate polyols and their copolymers; C. One or more crosslinking agents C, selected from amino plastic resins and end-capped polyisocyanates; D. One or more coating additives D, selected from light stabilizers, UV absorbers, thickeners, surfactants, catalysts such as those suitable for catalyzing crosslinking reactions, flame retardants, defoaming and degassing additives, conductivity modifiers, soluble dyes, wetting and dispersing agents, corrosion inhibitors, and rheology modifiers. E. One or more pigments and / or fillers E, derived from color pigments and effect pigments; and F. One or more organic solvents F, selected from water-soluble and / or water-dispersible organic solvents.

9. The method for coating a substrate according to claim 8, wherein, The amounts of the components in this water-based primer coating material are within the following ranges: Based on 10 to 75 wt.-%, preferably 15 to 65 wt.-%, more preferably 25 to 55 wt.-%, of total binder solids; Based on 5 to 40 wt.-%, preferably 8 to 40 wt.-%, more preferably 10 to 35 wt.-%, of total binder solids; Based on 20 to 50 wt.-%, preferably 25 to 45 wt.-%, more preferably 30 to 40 wt.-%, of total binder solids; Based on 1 to 8 wt.-% of total binder solids, preferably 2 to 7 wt.-% and more preferably 2.5 to 6 wt.-% of D; Based on the total weight of the water-based primer coating material, 5 to 40 wt.-%, preferably 10 to 35 wt.-%, more preferably 15 to 30 wt.-%, and E, and Based on the total weight of the water-based primer coating material, 5 to 25 wt.-%, preferably 8 to 20 wt.-%, more preferably 10 to 17 wt.-%, of F.

10. The method for coating a substrate according to claim 8 or 9, wherein, The weight ratio of A to B is in the range of 6:1 to 0.5:1, preferably 5.5:1 to 1:1, and more preferably 5:1 to 1:

1.

11. The method for coating a substrate according to any one or more of the preceding claims, wherein, Step ii. is followed by iii. Applying one or more base coat materials onto the base coat to form one or more base coats, and iv. Applying one or more clear coat materials onto the one or more base coats to form one or more clear coats, and v. To cure, individually or together, any of the layers formed in steps ii. to iv.

12. The method for coating a substrate according to claim 11, wherein, After step ii. and before step iii., the primer coating is preferably dried at least partially at a temperature in the range of 15°C to 35°C, more preferably 20°C to 30°C; and After step iii. and before step iv., the one or more base coats are preferably dried at least partially at a temperature in the range of 50°C to 80°C, more preferably 55°C to 75°C; and Following step iv., the layers obtained in steps ii., iii. and iv. are co-cured in step v. at a temperature ranging from 120°C to 160°C, more preferably from 130°C to 150°C.

13. A coated substrate, which can be obtained by the method according to any one or more of the preceding claims.

14. Use of the waterborne primer coating composition as defined in any one or more of the preceding claims in vehicle coating, preferably automotive OEM coating, in coating a substrate comprising at least two components as defined in any one or more of the preceding claims.

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