Low-temperature curable multilayer coating system with excellent appearance

Abstract

The present invention relates to a multilayer coating system present on a substrate comprising at least three layers L1 to L3, wherein the layer L1 is obtained from a primer coating composition comprising at least two components A) and B) separated from each other, the component A) contains in particular at least one constituent a2), which is at least one (meth)acrylic polymer modified with at least one chlorinated polyolefin, the polymer containing functional groups reactive towards NCO groups, the layer L2 is obtained from a basecoat composition, and the layer L3 is obtained from a clearcoat composition, a method for preparing a multilayer coating system using said primer coating system, and a kit-of-parts comprising at least said primer coating system and the clearcoat composition or clearcoat system separated from each other.

Description

【Technical Field】 【0001】 The present invention relates to a multilayer coating system present on a substrate and comprising at least three layers L1 to L3, wherein layer L1 is obtained from a specific primer coating composition, layer L2 is obtained from a basecoat composition, and layer L3 is obtained from a clearcoat composition, a method for preparing a multilayer coating system using the specific primer coating composition, a primer coating system suitable for preparing the specific primer coating composition, and a kit-of-parts comprising at least separately a clearcoat composition or a clearcoat system suitable for preparing a clearcoat composition. 【Background Art】 【0002】 In a typical automotive coating process, usually, a plurality of layers are applied to the surface of a suitable substrate in the form of a multilayer coating system. In particular, when a plastic or fiber-reinforced plastic substrate is used, at least a primer, at least one basecoat, and a topcoat, in particular a clearcoat as the outermost layer, are applied in this order. At least the basecoat and the topcoat are typically applied today using wet-on-wet coating. Thereafter, the coated substrate is passed through an oven at a temperature that cures at least the basecoat(s) and the topcoat, such as the clearcoat, simultaneously, for example, in a 2C1B process. In some cases, the primer coat is also cured at this stage together with the basecoat(s) and the topcoat, in particular the clearcoat, for example, in a 3C1B process. 【0003】 As the demand for lower fuel consumption in automobiles increases, the use of lightweight materials used as automotive parts, particularly external body parts, has attracted particular attention. For this reason, in particular, the aforementioned reinforced plastics, particularly carbon fiber-reinforced plastics (CFRP) substrates, are required to be used as substrates for preparing a multilayer coating system on the surface of automotive parts because they are lightweight substrates. 【0004】 In addition to the general advantages of using such lightweight substrates, there are usually a very large number of requirements that must be met and / or satisfied by not only these substrates but also the single layers present within multilayer coating systems on other substrates used in the automotive industry. These requirements are due not only to regulations but also to the quality standards set by the automotive industry. Thus, multilayer coatings must exhibit or demonstrate a number of desired properties to at least a sufficient extent to meet these requirements. In particular, automotive exterior parts must have an excellent paint finish often referred to in the automotive industry as "Class A appearance". 【0005】 When applying a conventional multilayer coating system, particularly on a fiber-reinforced substrate such as a CFRP substrate, when the coated substrate is cooled, undesirable unevenness, i.e., coating defects, are observed after the firing process. This unevenness can propagate to the top layer of the multilayer coating system applied on a substrate such as a CFRP substrate and impair the paint finish. This undesirable defect is known as the telegraph effect. The telegraph phenomenon occurs mainly due to the relatively low glass transition temperature (T g ) of the plastic substrate and the difference in the coefficient of thermal expansion (CTE) between the plastic substrate and the reinforcing fibers (usually glass fibers and / or carbon fibers) present therein. However, the observed undesirable surface unevenness is not only the mere result of the aforementioned telegraph effect due to the (fiber-reinforced) plastic substrate used, but may also occur additionally or alternatively due to the undesirable telegraph effect at the interface between the coating layers of the multilayer coating system used on different types of substrates. 【0006】 Therefore, there is a need to provide a novel multi-layer coating system that does not exhibit any undesirable telegraphing effect, or exhibits at least less telegraphing effect than that observed in conventional multi-layer coating systems, on a substrate, particularly a plastic substrate including a reinforced plastic substrate such as CFRP, i.e., exhibits an excellent coating finish ("Class A appearance"), while at the same time not showing any disadvantages as far as other relevant properties of the multi-layer coating system, particularly packaging stability, etc. are concerned. 【Summary of the Invention】 【Problems to be Solved by the Invention】 【0007】 Therefore, the underlying object of the present invention is to provide a multi-layer coating system on a substrate, particularly a plastic substrate including a reinforced plastic substrate such as CFRP, which does not exhibit any undesirable telegraphing effect, or exhibits at least less telegraphing effect than the telegraphing effect observed in conventional multi-layer coating systems, and thus exhibits an excellent coating finish ("Class A appearance"), while at the same time not showing any disadvantages as far as other relevant (important) properties of the multi-layer coating system, particularly packaging stability, etc. are concerned. 【Means for Solving the Problems】 【0008】 This object is solved by the subject matter of the patent application scope of the present application and by those preferred embodiments disclosed herein, i.e., by the subject matter described herein. 【0009】 The first subject matter of the present invention is present on an optionally pre-coated substrate and comprises at least three coating layers L1, L2 and L3 that are different from each other, i.e., a multi-layer coating system comprising a first coating layer L1, a second coating layer L2 and a third coating layer L3, wherein the first coating layer L1 is applied on at least a part of the optionally pre-coated substrate and is obtained from a primer coating composition, The primer coating composition is obtained from a primer coating system comprising at least two components A) and B) and optionally at least one further component C), which are different from one another and separated from one another, Component A) comprises at least constituent a2) and optionally at least constituent a1), which are different from one another, i.e. optionally at least one organic solvent a1), and at least one polymer a2) which is a (meth)acrylic polymer containing a functional group reactive towards NCO groups and modified with at least one chlorinated polyolefin and comprises Component B) comprises at least two constituents b2) and optionally at least one constituent b1), which are different from one another, i.e. optionally at least one organic solvent b1), and at least one organic constituent b2) having on average two or more NCO groups and comprises Any optional component C) is a reducing agent component and comprises at least one organic solvent c1), A second coating layer L2 is applied over the first coating layer L1 and is obtained from a basecoat composition, A third coating layer L3 is applied over the second coating layer L2 and is obtained from a clearcoat composition, Preferably, layer L3 is obtained from a 2K clearcoat composition which is obtained from a clearcoat system comprising at least two components D) and E) and optionally at least one further component F), which are different from one another and separated from one another, Component D) comprises at least constituent d2) and optionally at least one constituent d1), which are different from one another, i.e. optionally at least one organic solvent d1), and at least one OH-functional (meth)acrylic polymer d2) and comprises Component E) comprises at least two constituents e2) and optionally at least one constituent e1), which are different from one another, i.e. optionally at least one organic solvent e1), and At least one organic constituent e2) having on average two or more NCO groups, at least some of these NCO groups having reacted with at least one organosilane before the constituent e2) is incorporated into component E). comprising, and any component F) is a reducing agent component and is at least one organic solvent f1). 【0010】 A further subject of the invention is for application onto a substrate selected from a metallic substrate and a plastic substrate, preferably selected from a plastic substrate, more preferably selected from a fiber-reinforced plastic substrate, even more preferably selected from a carbon fiber-reinforced plastic substrate, of a multilayer coating system comprising at least three different coating layers L1, L2 and L3 as defined above and below herein. A method of use. 【0011】 A further subject of the invention is a method of preparing a multilayer coating system on at least one surface of an optionally precoated substrate, comprising at least steps 1) to 3) and optionally 4), namely 1) applying at least partially a first coating composition onto at least one surface of an optionally precoated substrate to form a first coating film on said surface, wherein the first coating composition is a primer coating composition used according to the invention as defined above and below herein, a step, 2) applying at least one base coat composition as at least one second coating composition onto the first coating film present on the substrate obtained after step 1), preferably before curing the first coating film, to form a second coating film preferably adjacent to the first coating film, and 3) Apply a clearcoat composition as the third coating composition to the second coating film present on the substrate obtained after step 2), preferably before curing the second coating film, to form a third coating film which is preferably adjacent to and preferably the outermost layer of a multilayer coating formed on the second coating film. The step wherein the third coating composition is preferably the clearcoat composition used according to the invention as defined above and below herein. 4) Optionally, a step of curing the first, second and third coating films together to obtain a multilayer coating system comprising cured first, second and third coating layers, in particular, when a plastic substrate or a fiber-reinforced plastic substrate is used as the optionally precoated substrate, curing is preferably carried out at a temperature not exceeding 80°C, more preferably not exceeding 70°C, still more preferably not exceeding 60°C, and even more preferably not exceeding 55°C. A method comprising. 【0012】 A further subject of the present invention is at least A primer coating system used according to the invention as defined above and below herein, comprising at least two components A) and B) and optionally at least one further component C), and A clearcoat composition, preferably a 1K-clearcoat composition, or a 2K-clearcoat system suitable for preparing a clearcoat composition, preferably comprising at least two components D) and E) and optionally at least one further component F), as defined above and below herein. A kit-of-parts comprising them separately from each other. 【0013】 Particularly surprisingly, an excellent paint finish (a "Class A appearance") with a long wavelength (LW) value ≤ 10 and a short wavelength (SW) value ≤ 20 is achieved for the multi-layer coating system of the present invention present on a substrate, particularly a plastic substrate, such as a thermoplastic polyolefin (TPO) and a (carbon) fiber-reinforced plastic substrate containing carbon fiber-reinforced polyamide. The multi-layer coating system includes a primer layer derived from a primer film obtained from a 2K-primer coating composition used according to the present invention. Further, this effect is also observed for a plurality of different types of other substrates, such as metal substrates, and it is surprisingly found that it does not depend on the nature of the base coat materials (solvent-based base coats and water-based base coats) used as intermediate coats (base coats) for preparing the multi-layer coating system. 【0014】 It has been found that the aforementioned advantages are particularly observed when preparing the multi-layer coating system of the present invention by the 3C1B method of simultaneously curing the primer, base coat, and clear coat films. Such a method has the further advantage that the process time is shortened and only one baking step is required, which is economically and environmentally advantageous. 【0015】 Furthermore, it has been found that the multi-layer coating system can be obtained by curing (baking) at a low temperature of 50 °C, which is highly energy-efficient and environmentally friendly, and is particularly advantageous when the substrate used is a plastic substrate, particularly a carbon fiber-reinforced plastic substrate. 【0016】 Furthermore, and particularly surprisingly, it has been found that the above-described excellent paint finish is not achieved when the multi-layer coating system is present on the substrate in combination with the achievement of other necessary relevant properties, in the following cases: (i) when a commercially available (modified) 1K primer coating formulation is used for comparison instead of the primer coating composition used according to the present invention (see Comparative Examples CE1 and CE5 disclosed in the experimental section), (ii) when a 2K primer coating formulation not containing component a2) is used for comparison instead of the primer coating composition used according to the present invention (see Comparative Examples CE1 and CE5 disclosed in the experimental section), (ii) when a 2K primer formulation not containing component a2) is used for comparison instead of the primer coating composition used according to the present invention (see Comparative Example CE2 disclosed in the experimental section), and (iii) when a different 2K clearcoat formulation is used for comparison instead of the primer coating composition used according to the present invention (see Comparative Examples CE3 and CE4 disclosed in the experimental section). In each of the cases of CE2, CE3, CE4, and CE5, too high SW values were observed in order to meet the "Class A requirements" regarding appearance. CE2 and CE4 also showed too high LW values. In the case of CE1, the "Class A requirements" were met, but CE1, like each of CE2 to CE5, was inferior in other required relevant properties, namely, had poor tape adhesion after humidity exposure, insufficient steam injection, and insufficient thermal shock properties. 【0017】 Furthermore, the primer coating film prepared according to the present invention obtained from the primer coating composition used according to the present invention has the ability to at least partially cure the base coat film applied on the primer coating film even at a low temperature of 50°C. This is due to the migration of isocyanate from the primer film to the base coat film. In particular, when the primer coating composition used contains an excessive amount of component b2) having on average two or more NCO groups, and this component migrates into the aforementioned base coat film (applied on the primer coating film obtained from the primer coating composition on a substrate), it has been found that at least partial curing of the base coat film is achieved when the film contains at least one, preferably polymeric, component containing a functional group that is reactive with the NCO groups of component b2). 【Mode for Carrying Out the Invention】 【0018】 The term "comprising" in the context of the present invention preferably has the meaning of "consisting of" in relation to, for example, a primer coating composition, a clear coat composition, or one of the components of a primer coating or clear coat system. For example, in relation to a primer coating composition, a clear coat composition, or one of the components of a primer coating or clear coat system, in addition to any essential components present therein, one or more of the further optional components identified below may also be included therein. Each component is present in its preferred embodiments identified below in each case. 【0019】 For each of the coating compositions, for example primer coating compositions or clear coat compositions, the proportion and amount in any mass % (by mass) of the components shown below are each 100 mass % in total with respect to the total mass of each coating composition. The same applies to each component of the coating system, for example component A) or B) of the primer coating system, or components D) and E) of the clear coat system. The proportion and amount in any mass % (by mass) of the components shown below present in one of these components are each 100 mass % in total with respect to the total mass of each respective component. 【0020】 Multilayer coating system Layers L1, L2, L3 and substrate The first main subject of the present invention is a multilayer coating system present on an optionally pre-coated substrate and comprising at least three coating layers L1, L2 and L3 that are different from one another. 【0021】 Preferably, the at least three coating layers L1, L2 and L3 are arranged adjacent to one another. Preferably, the third coating layer L3 is the outermost coating layer of the multilayer coating system. 【0022】 Preferably, the multilayer coating system is obtained by the method of the present invention for preparing the multilayer coating system described in detail below. 【0023】 Each of the layers L1, L2, and L3 represents a cured coating film. The first layer L1 is obtained from the first coating film, the second layer L2 is obtained from the second coating film, and the third layer L3 is obtained from the third coating film. The first coating film is a primer coating film, the second coating film is a base coat film, and the third coating film is a clear coat film. The term "primer" is known to those skilled in the art. In the case of a metal substrate, the primer is typically applied after a cured electrodeposition coating layer is provided on the substrate. In this case, the cured electrodeposition coating film is present under and preferably adjacent to the primer coating film. This is an example of a pre-coated substrate. In the case of a non-metal substrate, such as a plastic substrate including a fiber-reinforced plastic substrate, the primer coating film typically represents the first coating film applied to its surface. The term "base coat" is also known to those skilled in the art and is defined, for example, in Roempp Lexikon, paints and printing inks, Georg Thieme Verlag, 1998, 10th edition, page 57. Thus, the base coat is used to impart color and / or optical effects by using the base coat as an intermediate coating composition, particularly in automotive coatings and general industrial color coatings. This is generally applied to an optionally pre-coated metal substrate or plastic substrate. At least one additional clear coat film is applied, particularly to protect the base coat film from environmental effects. The terms "clear coat", "clear coating", or "clear coat film" are also known to those skilled in the art and represent the transparent outermost layer of a multi-layer coating structure applied to a substrate. 【0024】 Preferably, the cured primer film (layer L1) preferably obtained after performing step 4) of the method of the present invention for preparing the multilayer coating system has a dry film thickness in the range of 10 to 35 μm. Preferably, the cured base coat film (layer L2) preferably obtained after performing step 4) of the method of the present invention for preparing the multilayer coating system has a dry film thickness in the range of 12 to 35 μm. Preferably, the cured clear coat film (layer L3) preferably obtained after performing step 4) of the method of the present invention for preparing the multilayer coating system has a dry film thickness in the range of 30 to 60 μm. 【0025】 The substrate can be an automotive vehicle body or a part thereof. The substrate can be a metal substrate, but can also be a plastic substrate, such as a polymer substrate and a fiber-reinforced plastic substrate. 【0026】 Suitable as the metal substrate used according to the present invention are all substrates customarily used and known to those skilled in the art. The substrate used according to the present invention is preferably a metal substrate, more preferably steel, preferably bare steel, cold-rolled steel (CRS), hot-rolled steel, zinc-plated steel, such as hot-dip galvanized steel (HDG), alloy zinc-plated steel (e.g., Galvalume, Galvannealed or Galfan, etc.) and aluminum-plated steel, aluminum, magnesium, and Zn / Mg alloys and Zn / Ni alloys selected from the group consisting of. Particularly preferred substrates are parts of a production vehicle body or a complete automotive body. The metal substrate may be pretreated with at least one metal phosphate, such as zinc phosphate, and / or may be pretreated with at least one oxalate. This type of pretreatment by phosphate treatment or oxalate treatment is usually carried out after cleaning the substrate and before electrocoating the substrate, and is a pretreatment process customary particularly in the automotive industry. The metal substrate may further include a cured electrocoating layer as a precoat. 【0027】 Preferably, a thermoplastic polymer is used as the plastic substrate. Suitable polymers include poly(meth)acrylates such as polymethyl (meth)acrylate and polybutyl (meth)acrylate, polyesters such as polyethylene terephthalate, polybutylene terephthalate, polyvinylidene fluoride, polyvinyl chloride, polycarbonate and polyvinyl acetate, polyamides, polyolefins such as polyethylene, polypropylene, polystyrene, and polybutadiene, polyacrylonitrile, polyacetal, polyacrylonitrile - ethylene - propylene - diene - styrene copolymer (A - EPDM), ASA (acrylonitrile - styrene - acrylate copolymer) and ABS (acrylonitrile - butadiene - styrene copolymer), polyetherimide, phenolic resin, urea resin, melamine resin, alkyd resin, epoxy resin, polyurethanes including TPU, polyether ketone, polyphenylene sulfide, polyethers, polyvinyl alcohol, and mixtures thereof. Polycarbonate and poly(meth)acrylate are particularly preferred. 【0028】 Furthermore, and most preferably, a fiber - reinforced plastic substrate is used. Glass fibers and / or carbon fibers, most preferably carbon fibers, can be specifically used for reinforcement. An example of a suitable carbon - fiber - reinforced plastic substrate is a carbon - fiber - reinforced polyamide substrate. As outlined above, most preferably, the substrate is a plastic substrate, more preferably a fiber - reinforced plastic substrate, and even more preferably a carbon - fiber - reinforced plastic substrate. 【0029】 Primer coating composition The first coating layer L1 is applied on at least a part of a pre-coated substrate optionally, said layer L1 is obtained from a primer coating composition, and the composition is obtained from a primer coating system comprising at least two components A) and B), and optionally at least one further component C), said components being different from each other and separated from each other. The preparation of the primer coating composition can be carried out using conventional and known preparation and mixing methods and mixing units, or using conventional dissolvers and / or stirrers. 【0030】 Preferably, the primer coating composition is a solvent-based system, i.e., a coating composition based on an organic solvent(s), preferably due to the presence of constituents a1), b1) and optionally c1). The term "solvent-based system" in relation to the coating composition is preferably understood, for the purposes of the present invention, to mean that the aforementioned organic solvent(s) is / are present in an amount of preferably at least 35% by mass relative to the total mass of the coating composition as the main constituent(s) present in any solvent and / or diluent as a solvent and / or diluent. Thus, preferably, the coating composition is not an aqueous system, i.e., an aqueous coating composition. 【0031】 The primer coating composition preferably contains at most 75% by mass, more preferably at most 70% by mass, even more preferably at most 65% by mass, and still more preferably at most 60% by mass of the organic solvent(s) fraction, and these mass percentages are in each case relative to the total mass of the coating composition. Any conventional organic solvent known to those skilled in the art can be used as the organic solvent, i.e., as components a1), b1), and optionally c1). The term "organic solvent" is in particular known to those skilled in the art from Council Directive 1999 / 13 / EC of 11 March 1999. Examples of organic solvents that can be used have already been described above in connection with components a1), b1), and c1). Preferably, the primer coating composition contains an organic solvent(s) fraction in the range of 30 to 70% by mass relative to the total mass of the coating composition. 【0032】 Preferably, the primer coating composition has a total solids content of > 25% by mass, more preferably > 30% by mass, even more preferably > 35% by mass, and these mass percentages are in each case relative to the total mass of the coating composition. 【0033】 The total solids content of the primer coating composition is preferably in the range of > 20 to 60% by mass, more preferably > 25 to 55% by mass, even more preferably > 30 to 50% by mass, and still more preferably > 30 to 45% by mass, and these mass percentages are in each case relative to the total mass of the coating composition. The total solids content, in other words the non-volatile fraction, is determined according to the method described below. 【0034】 Preferably, the primer coating composition is obtained by mixing components A) and B) in a mass ratio of component A) / component B) in the range of 25:1 to 1:1. More preferably, the mixing is carried out at a mass ratio in the range of 20:1 to 1.1:1, even more preferably in the range of 17.5:1 to 2:1, and in particular in the range of 15:1 to 3:1. 【0035】 Preferably, the primer coating composition contains an excess of component b2) having on average two or more NCO groups, such that when said component migrates into the intermediate coating film, preferably a base coat film (applied over a primer coating film obtained from the primer coating composition on a substrate), at least partial curing of the intermediate coating film occurs, which is achieved when said intermediate coating film contains at least one preferably polymeric component containing a functional group reactive towards NCO groups. The term "excess" in this context preferably means a molar excess or a mass excess, more preferably a mass excess. 【0036】 The term "in excess of component b2)" preferably means that an amount of component b2) derived from component "B" in an amount of preferably 5 to 20% by weight, preferably 7.5 to 15% by weight, more preferably 10 to 12.5% by weight (these % by weight in each case being relative to the total mass of component b2) originally present in said component B)) remains in the primer coating composition obtained after mixing, and that amount is not used for crosslinking with a related component, such as component a2) of component A), due to the use of component b) in an overstoichiometric amount. This enables at least partial curing via migration of NCO when applying a subsequently applied base coat film over a primer coating film obtained by applying a primer coating material composition onto the surface of a substrate. 【0037】 Primer coating system The primer coating system used to prepare the primer coating composition is a two-component (2K) or multi-component coating system. Separation from each other in this context means that components A), B) and optionally C) of the coating system are stored separately until they are mixed with each other to prepare the primer coating composition. If the coating system is a two-component coating system, it preferably consists of components A) and B). When at least two components A) and B) are mixed and the resulting composition is applied to the surface of the substrate, preferably at least a polyurethane or polyurethane-based coating film is preferably formed by the reaction of a functional group such as the OH group of at least one constituent a2) and the isocyanate group of at least one constituent b2). 【0038】 Preferably, both coating components A) and B) and any optional component C) are water-free or essentially water-free. The same applies to the coating compositions obtained therefrom. In the context of the present invention, the term "water-free" preferably means that no water is present at all. In the context of the present invention, the term "essentially water-free" preferably means that essentially no water is present. This means that at least no water is intentionally added to any of components A), B) and optionally C) used according to the present invention, nor to the coating compositions obtained therefrom. However, it does not exclude the presence of residues of water formed during the preparation of any of the constituents used to prepare components A), B) and optionally C) according to the present invention. Preferably, the amount of any water present in each of components A), B) and optionally C) is less than 1% by weight, more preferably less than 0.5% by weight, even more preferably less than 0.1% by weight, still more preferably less than 0.05% by weight, yet more preferably less than 0.01% by weight, particularly less than 0.005% by weight or less than 0.001% by weight, these percentages by weight being in each case relative to the total weight of component A) or B) or optionally C). Preferably, both coating components A) and B) and optionally component C) are based on a solvent system, i.e. on one or more organic solvents. Thus, preferably, the coating system is not an aqueous system, i.e. an aqueous coating system. 【0039】 Component (A) Constituent (A) comprises at least constituent a2) and optionally at least one further constituent a1), which are different from each other, but may additionally comprise further optional constituents, such as constituents a3), a4), a4a), a5), a6), a7), a8), a9) and / or a10). Any constituents present are different from each other. 【0040】 Preferably, the primer coating-based component A) has a total solids content of > 20% by mass, preferably > 25% by mass, more preferably > 30% by mass, and even more preferably > 45% by mass, based on the total mass of component (A). The total solids content of component A) of the primer coating system is preferably in the range of > 20 to 60% by mass, more preferably 25 to 50% by mass, and even more preferably 30 to 45% by mass, and these mass percentages are in each case relative to the total mass of component A). The total solids content, in other words the non-volatile fraction, is determined according to the method described below. 【0041】 Any constituent a1) Any constituent a1) is at least one organic solvent. Examples of such organic solvents include heterocyclic, aliphatic or aromatic hydrocarbons, monoalcohols or polyhydric alcohols, in particular methanol and / or ethanol, ethers, esters, ketones, and amides, such as N-methylpyrrolidone, N-ethylpyrrolidone, dimethylformamide, toluene, xylene, butanol, ethyl glycol and butyl glycol and also their acetates, butyl diglycol, diethylene glycol dimethyl ether, cyclohexanone, methyl ethyl ketone, methyl isobutyl ketone, acetone, isophorone, or mixtures thereof. Component A) may contain a plurality of organic solvents a1). 【0042】 Preferably, the amount of any constituent a1) in component (A) is in the range of 0 to 80% by mass, or 10 to 80% by mass, more preferably 25 to 75% by mass, and even more preferably 40 to 70% by mass, and these mass percentages are in each case relative to the total mass of component A). 【0043】 Constituent a2) Component a2) is at least one (meth)acrylic polymer modified with at least one chlorinated polyolefin and contains functional groups that are reactive towards NCO groups, such as OH groups, thiol groups, carbamate groups, COOH groups and / or amino groups. Preferably, component a2) is an OH-functional polymer. Component a2), for example an OH-functional polymer, preferably functions as a film-forming binder. For the purposes of the present invention, the term "binder" is understood to be the non-volatile constituent of a coating composition that is responsible for film formation in accordance with DIN EN ISO 4618 (German version, date: March 2007). Thus, the pigments and / or fillers contained therein are not included in the term "binder". Preferably, component a2) represents the main binder. As the main binder in the meaning of the present invention, a binder constituent is preferably mentioned when there are no other binder constituents present in the coating composition or the components used for its preparation in a higher proportion relative to the total mass of the coating composition or the component. 【0044】 The term "polymer" is known to those skilled in the art and, for the purposes of the present invention, includes polyadducts, polymers and polycondensates. The term "polymer" includes both homopolymers and copolymers. 【0045】 If component a2) is at least one OH-functional polymer, it preferably contains on average two or more OH groups. 【0046】 Preferably, component a2) is at least one OH-functional (meth)acrylic polymer modified with at least one chlorinated polyolefin. "Modified" preferably means that the chlorinated polyolefin is covalently bonded to the (meth)acrylic polymer. The chlorinated polyolefin can be connected to the backbone (main chain) and / or at least one side chain of the (meth)acrylic polymer. An example of such a polymer is Acrydic® CL-408. 【0047】 Preferably, the primer coating-based component A) contains at least one component a2) in an amount in the range of 5.0 to 50.0% by mass, more preferably 10.0 to 45.0% by mass, even more preferably 15.0 to 40.0% by mass, and still more preferably 17.5 to 35.0% by mass, and these mass percentages are in each case relative to the total mass of component A). 【0048】 Any catalyst components a3), a4) and / or a4a) Optionally, at least one of the catalyst components a3), a4) and a4a) may be present in the primer coating-based component A). 【0049】 At least one optionally present catalyst a3) is suitable for crosslinking of NCO groups and is preferably selected from organotin catalysts. Preferably, at least one catalyst a3) is suitable for crosslinking of the NCO groups of component b2) of component B). 【0050】 Preferably, the primer coating-based component A) contains at least one catalyst a3) in an amount in the range of 0.001 to 1.00% by mass, more preferably 0.002 to 0.80% by mass, even more preferably 0.003 to 0.60% by mass, still more preferably 0.004 to 0.40% by mass, yet more preferably 0.005 to 0.20% by mass, and most preferably 0.007 to 0.15% by mass, and these mass percentages are in each case relative to the total mass of component A). 【0051】 The catalyst a3) is preferably selected from organometallic catalysts and more preferably from organotin catalysts. Examples of organotin catalysts are DOTL (dioctyltin dilaurate) and DBTL (dibutyltin dilaurate). DOTL is particularly preferred. 【0052】 At least one optionally present catalyst a4) is selected from phosphorus-containing organic components that are not blocked by any amine and is preferably suitable for crosslinking of Si-containing functional groups, particularly when component b3) is present, in component b3) of component B). 【0053】 Preferably, the primer coating-based component A) contains at least one catalyst a4) in an amount in the range of 0.01 to 1.0% by mass, more preferably 0.02 to 0.8% by mass, even more preferably 0.03 to 0.6% by mass, still more preferably 0.04 to 0.5% by mass, and yet more preferably 0.05 to 0.4% by mass, and these mass percentages are in each case based on the total mass of component A). 【0054】 In particular, at least one catalyst a4) which is a phosphorus-containing catalyst does not contain any nitrogen. As the catalyst a4), a plurality of, for example, two different catalysts can be used. 【0055】 Examples of phosphorus-containing catalysts suitable for use as the catalyst a4) are preferably substituted phosphonic acid diesters and diphosphonic acid diesters selected from the group consisting of acyclic phosphonic acid diesters, cyclic phosphonic acid diesters, acyclic diphosphonic acid diesters, and cyclic diphosphonic acid diesters. However, more specifically, as at least one catalyst a4), substituted phosphoric acid monoesters and phosphoric acid diesters selected from the group consisting of acyclic phosphoric acid monoesters and diesters and cyclic phosphoric acid monoesters and diesters are preferably used. Since the catalyst a4) is not blocked by any amine, none of these esters can exist in the form of amine adducts. 【0056】 Preferably, at least 2-ethylhexyl acid phosphate is used as at least one catalyst a4). The term "2-ethylhexyl acid phosphate" includes both monoethylhexyl acid phosphate and diethylhexyl acid phosphate. 【0057】 The catalyst a4) is a phosphorus-containing organic constituent that is not blocked by at least one amine, and can be used in combination with at least one catalyst a4a) that is blocked by at least one amine, i.e., also nitrogen-containing, and is preferably used in combination. However, it is also possible to use only the catalyst a4a) and present it in component A), and it is not necessarily required to use the catalyst a4) as well. 【0058】 Preferably, the component A) of the primer coating system contains at least one optionally present catalyst a4a) in an amount in the range of 0.05 to 2.0% by mass, more preferably 0.06 to 1.8% by mass, even more preferably 0.07 to 1.6% by mass, still more preferably 0.08 to 1.4% by mass, yet more preferably 0.09 to 1.2% by mass, and particularly preferably 0.10 to 1.0% by mass. These mass percentages are in each case relative to the total mass of component A). 【0059】 Preferably, the amount of the catalyst a4a) (when present) exceeds the amount of the catalyst a4). Preferably, the relative mass ratio of the catalysts a4) and a4a) to each other in component A) is in the range of 0.1 to 1.0 to 0.9:1.0, more preferably 0.2 to 1.0 to 0.8 to 1.0, and even more preferably 0.3 to 1.0 to 0.7 to 1.0. 【0060】 Preferably, at least one catalyst a4), such as 2-ethylhexyl acid phosphate, is present in an amount in the range of 0.01 to 0.4% by mass, and at least one catalyst a4a) is present in an amount in the range of 0.05 to 1.0% by mass. 【0061】 Preferably, at least one catalyst a4a) is selected from phosphorus-containing organic components, more preferably from acyclic phosphoric acid diesters, acyclic phosphoric acid monoesters, cyclic phosphoric acid diesters and cyclic phosphoric acid monoesters, and each of the aforementioned phosphoric acid diesters and monoesters is in the form of an adduct with at least one amine (i.e., blocked with at least one amine), preferably in the form of an adduct with at least one tertiary amine. 【0062】 Optional component a5) - condensation product Optionally and preferably, component A) of the primer coating system further comprises at least one component a5) different from any of components a1) to a4) and a4a), which is a condensation product and is obtained by the reaction of at least (i) at least one organosilane having at least one hydrolyzable group and (ii) at least one type of silica. The condensation product a5) is also referred to as a "condensate" herein. 【0063】 Preferably, the molar ratio of at least one organosilane to at least one type of silica used in the preparation of the condensation product a5) is in the range of 10:1 to 1:1, more preferably 8:1 to 1:1, even more preferably 6:1 to 1:1, still more preferably 4:1 to 1:1, also more preferably 4:1 to 1.1:1, still more preferably 4:1 to 1.5:1, and most preferably 4:1 to 2:1. 【0064】 Preferably, at least one condensation product a5) is present in component A) in the range of 1.0 to 25.0% by mass, more preferably 2.0 to 20.0% by mass, even more preferably 3.0 to 17.5% by mass, still more preferably 4.0 to 15.0% by mass, also more preferably 5.0 to 14.0% by mass, even more preferably 6.0 to 13.0% by mass, and most preferably 7.0 to 12.0% by mass, and these mass percentages are in each case based on the total mass of component A). 【0065】 Preferably, the condensation product a5) has an average particle size in the range of 10 to 100 nm, more preferably 15 to 80 nm, even more preferably 20 to 70 nm, still more preferably 25 to 60 nm, yet more preferably 30 to 50 nm, and most preferably 35 to 45 nm, and in each case is measured by DLS (dynamic light scattering). The DLS method used is specified in the "Method" section below. Preferably, the average particle size is measured at a high shear viscosity of 5 to 15 cP using a CAP2000 viscometer. 【0066】 The term "silica" as used in this context is a term clear to those skilled in the art and refers to SiO2. Preferably, at least one type of silica used is preferably in the form of an aqueous dispersion of colloidal silica particles that is basic or acidic, preferably basic. Preferably, the silica particles have an average particle size of silica in the range of 5 to about 300 nm, more preferably 5 to 200 nm, even more preferably 7.5 to 100 nm, still more preferably 7.5 to 50 nm, and most preferably 10 to 30 nm. The average particle size is measured by DLS. The DLS method used is specified in the "Method" section below and is the same as the method used for measuring the average particle size of the condensation product a5). 【0067】 As outlined herein, both acidic and basic colloidal silica dispersions can be used. However, a colloidal silica dispersion having a low alkali content is preferred. 【0068】 Commercially available silica products that can be used include, for example, Ludox® (Sigma Aldrich), Snowtex® (Nissan Chemical), Bindzil® (AkzoNobel), Nalco® colloidal silica (Nalco Chemical Company), and Levasil® (AkzoNobel) products. Particularly preferred colloidal silica products that can be used include Nalco® 1034A (Nalco Chemical Company), Snowtex® O40, Snowtex ST - 033, and Snowtex® OL - 40 (Nissan Chemical), Ludox® AS40 and Ludox® HS40 (Sigma - Aldrich), Levasil 200 / 30 and Levasil® 200S / 30 (now Levasil CS30 - 516P) (AkzoNobel), and Cab - OSperse® A205 (Cabot Corporation). 【0069】 At least one organosilane having at least one hydrolyzable group may optionally contain at least one non - hydrolyzable group, which is preferably an organic, preferably aliphatic residue having 1 to 10 carbon atoms, and preferably contains them and may further contain at least one functional group optionally. 【0070】 Preferably, at least one organosilane having at least one hydrolyzable group is a monosilane and has at least two, particularly preferably at least three, hydrolyzable groups X, and / or is at least one bis(silane), preferably having at least four, particularly preferably six, hydrolyzable groups X. However, it is also possible to use a monosilane having four hydrolyzable groups, i.e., a monosilane that does not contain any non - hydrolyzable residues, such as tetramethoxysilane and / or tetraethoxysilane. 【0071】 Preferably, at least one organosilane having at least one hydrolyzable group is a monosilane and has at least two, particularly preferably at least three, hydrolyzable groups X and / or is at least one bis(silane), preferably having at least four, particularly preferably six, hydrolyzable groups X. However, it is also possible to use a monosilane having four hydrolyzable groups X, i.e., a monosilane that does not contain any non-hydrolyzable residues, such as tetramethoxysilane and / or tetraethoxysilane. 【0072】 Preferably, at least one organosilane having at least one hydrolyzable group has the general formula (1) and / or (2) Si(X) 4-y (R) y (1), Si(X) 3-z (T) z -(RA)-Si(X) 3-z (T) z (2), is an organosilane of wherein, in the case of general formula (1), X is each independently a hydrolyzable group, preferably each independently selected from O-C 1~4 alkyl, the parameter y is an integer in the range of 0 or 1 to 3, preferably at least 1, preferably exactly 1, and R is a non-hydrolyzable organic residue, preferably an aliphatic residue, preferably having 1 to 10 carbon atoms, and at least one of the residues R optionally contains at least one functional group, and wherein, in the case of general formula (2), X represents in each case independently of one another a hydrolyzable group, and preferably, in each case independently of one another, is selected from O-C 1~4 -alkyl, RA represents a divalent non-hydrolyzable organic residue, preferably an aliphatic residue, preferably having 1 to 10 carbon atoms, preferably not containing a functional group, The parameter z is, in each case, an integer in the range of 0 or 1 to 3, preferably 0 or 1 in each case, more preferably 1 in each case, and T is a non-hydrolyzable organic residue, preferably an aliphatic residue, preferably having 1 to 10 carbon atoms, different from the residue RA, and optionally contains at least one functional group. 【0073】 Examples of suitable functional groups are, in particular, thiol groups, amino groups, epoxide groups, in particular glycidoxy, epoxycyclohexyl and / or epoxycyclohexylethyl, OH-groups protected via suitable protecting groups, (meth)acrylate groups, vinyl groups, allyl groups, (meth)acryloxy groups, episulfide groups, ureido groups, thioureido groups, ether groups, thioether groups, sulfide groups, in particular disulfide trisulfide, tetrasulfide, pentasulfide, hexasulfide and / or polysulfide groups, xanthate groups, trithiocarbonate groups, dithiocarbonate groups, isocyanurate groups, and / or -Si(OR)3 groups (wherein R3 is an aliphatic residue, preferably having 1 to 10 carbon atoms). 【0074】 Examples of suitable organosilanes having at least one non-hydrolyzable group are, for example, (3-aminopropyl)trimethoxysilane, (3-aminopropyl)triethoxysilane, N-2-aminoethyl-3-aminopropyltrimethoxysilane, (3-mercaptopropyl)trimethoxysilane, (3-mercaptopropyl)triethoxysilane, (3-glycidyloxypropyl)trimethoxysilane, (3-glycidyloxypropyl)triethoxysilane, bis(2-ethyltrimethoxysilyl)amine, bis(3-propyltrimethoxysilyl)amine, bis(4-butyltrimethoxysilyl)amine, bis(2-ethyltriethoxysilyl)amine, bis(3-propyltriethoxysilyl)amine, bis(4-butyltriethoxysilyl)amine, methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, propyltrimethoxysilane, and / or propyltriethoxysilane. 【0075】 Preferably, the condensation reaction of at least one organosilane having at least one hydrolyzable group and at least one type of silica is carried out in an aqueous medium and is preferably catalyzed by at least one preferably organic acid. 【0076】 Preferably, at least one type of silica is added to at least one organosilane in the presence of water, preferably in the presence of 0.5 to 2.0 moles of water relative to the molar amount of at least one organosilane, and preferably in the presence of a catalytic amount of at least one acid, more preferably at least one organic acid such as acetic acid. The addition is preferably carried out at a temperature between 0 and 10 °C. The resulting mixture is preferably stirred at room temperature (18 - 23 °C) for 10 - 18 hours, and then preferably at least one acid in a catalytic amount, more preferably at least one organic acid such as acetic acid, and at least one ammonium salt such as tetrabutylammonium acetate (TBAA) as an additional catalyst are added. Then, the resulting mixture is preferably stirred for 1 - 10 hours. Preferably, the pH value of the mixture is maintained at pH 3 - 6. Then, the resulting mixture is preferably diluted with at least one water-miscible organic solvent, such as isopropanol (IPA), for example, at a mass ratio of 1:1. 【0077】 The preparation of an exemplary condensation product a5) prepared from methyltrimethoxysilane (MTMS) as the organosilane is outlined in the following scheme: 【0078】 【Chemical formula】 【0079】 Preferably, at least one condensation product a5) is present in the primer coating composition in an amount in the range of 1.0 to 25.0% by mass, more preferably 2.0 to 20.0% by mass, even more preferably 3.0 to 17.5% by mass, still more preferably 4.0 to 15.0% by mass, yet more preferably 5.0 to 14.0% by mass, even more preferably 6.0 to 13.0% by mass, and most preferably 7.0 to 12.0% by mass, and these mass percentages are in each case relative to the total mass of the primer coating composition. 【0080】 Further components Component A) of the primer coating system can optionally contain one or more further components, for example one or more of components a6) to a10), which are different from each other, different from each of components a1) to a3), and different from each of any components a4), a4a) and a5). Preferably, component A) of the primer coating system contains at least one, preferably at least two, more preferably at least three of components a6) to a8). 【0081】 Preferably, component A) of the primer coating system contains at least one epoxy resin as component a6), preferably in an amount in the range of 0.5 to 15.0% by mass, more preferably 1.0 to 10.0% by mass, even more preferably 1.5 to 7.5% by mass, still more preferably 2.0 to 5.5% by mass, and these mass percentages are in each case relative to the total mass of component A), and / or contains at least one chlorinated polyolefin as component a7), preferably in an amount in the range of 5.0 to 35% by mass, more preferably 6.0 to 30.0% by mass, even more preferably 7.0 to 25.0% by mass, still more preferably 8.0 to 20% by mass, and these mass percentages are in each case relative to the total mass of component A), and / or At least one pigment and / or filler is used as component a8), preferably in an amount of 5.0 to 30% by mass, more preferably 6.0 to 25.0% by mass, even more preferably 7.0 to 20.0% by mass, and still more preferably 8.0 to 15% by mass, and these mass percentages are in each case relative to the total mass of component A). 【0082】 The term "pigment" is known to those skilled in the art, for example, from DIN 55943 (date: October 2001). The "pigment" in the sense of the present invention preferably refers to a component in powder or flake form, which is substantially, preferably completely, insoluble in the medium surrounding it, such as one of the coating compositions used according to the present invention. The pigment is preferably a colorant and / or substance that can be used as a pigment due to its magnetic, electrical, and / or electromagnetic properties. The pigment preferably has a refractive index different from that of a "filler", and the refractive index of the pigment is ≧1.7. The term "filler" is known to those skilled in the art, for example, from DIN 55943 (date: October 2001). The pigment can be inorganic or organic. 【0083】 The primer coating system component A) can optionally contain one or more additional components, in addition to or as an alternative to one or more of the components a6) to a8). Component A) may contain one or more commonly used additives depending on the desired application. For example, component A) may contain at least one additive selected from the group consisting of reactive diluents, light stabilizers, antioxidants, degassing agents, emulsifiers, slip additives, polymerization inhibitors, plasticizers, free radical polymerization initiators, adhesion promoters, flow regulators, film-forming aids, flame retardants, corrosion inhibitors, desiccants, biocides, thickeners and / or matting agents. These can be used in known and customary proportions. Preferably, their content is 0.01 to 20.0% by mass, more preferably 0.05 to 15.0% by mass, particularly preferably 0.1 to 10.0% by mass, even more preferably 0.1 to 7.5% by mass, especially 0.1 to 5.0% by mass and most preferably 0.1 to 2.5% by mass, based on the total mass of the coating composition obtained by mixing components A), B) and optionally C). These mass percentages are in each case based on the total mass of the coating composition. 【0084】 In particular, the primer coating system component A) optionally contains at least one leveling agent and / or dispersant (wetting agent) as component a9) as an additive. Preferably, a9) is a (meth)acrylate polymer which contains at least one ether segment(s), preferably in the side chain, and / or at least one siloxane unit, preferably also in the side chain. Preferably, component a9) is present in the range of 0.10 to 5.0% by mass, more preferably 0.50 to 4.0% by mass, and even more preferably 0.80 to 3.5% by mass, based on the total mass of component A), especially when at least one optional component a5) is also present in component A). These mass percentages are in each case based on the total mass of component A). 【0085】 The primer coating-based component A) may optionally contain any kind of polymer that is a further polymer constituent different from a2), for example, having a functional group reactive with an NCO group, and this can be used as constituent a10). As examples, (meth)acrylic polymers (different from a2)), in particular (meth)acrylic polymers (not modified with at least one chlorinated polyolefin), polyesters, polyurethanes, polyureas, and polyethers, and mixtures thereof can be mentioned. 【0086】 Component B) Component B) may contain at least constituent b2) and optionally at least one constituent b1), which are different from each other, and may further contain any further optional constituents that are different from each other. 【0087】 Preferably, component B) does not contain any condensate a5), that is, the condensate a5) is present only in component A) of the primer coating system, if at all. 【0088】 Preferably, component B) of the primer coating system has a total solids content of >40% by mass, more preferably >45% by mass, even more preferably >50% by mass, and still more preferably >55% by mass, and these mass percentages are in each case based on the total mass of component B). The total solids content of component B) of the primer coating system is preferably in the range of 45 - 100% by mass, more preferably 50 - <100% by mass, even more preferably 55 - <100% by mass, and these mass percentages are in each case based on the total mass of component B). The total solids content, in other words the non-volatile fraction, is determined according to the method described below. 【0089】 Optional constituent b1) Any constituent b1) is at least one organic solvent. Examples of such organic solvents include those already mentioned above in connection with constituent a1). Component B) may contain a plurality of organic solvents b1). At least one organic solvent b1) may be the same as or different from at least one organic solvent a1). When a plurality of organic solvents are used as a1) and / or b1), a1) and b1) are both partially the same and partially different. 【0090】 Preferably, the amount of constituent b1) in component B) is in the range of 5 to 50% by mass, more preferably 10 to 40% by mass, even more preferably 15 to 35% by mass, and these mass percentages are in each case relative to the total mass of component B). 【0091】 Constituent b2) Constituent b2) is an organic constituent having on average two or more NCO groups. Preferably, constituent b2) has on average more than two NCO groups. 【0092】 Preferably, at least one organic constituent b2) present in component B) has an aliphatic or alicyclic structure and / or a parent structure derived from an aliphatic or alicyclic polyisocyanate by trimerization, dimerization, urethane formation, biuret formation, uretdione formation and / or allophanate formation. Trimers, namely isocyanurates of IPDI (isophorone diisocyanate) and / or HDI (hexamethylene diisocyanate), are particularly preferred. 【0093】 Suitable aliphatic polyisocyanates are preferably substituted or unsubstituted aliphatic polyisocyanates such as tetramethylene 1,4 - diisocyanate, hexamethylene 1,6 - diisocyanate, 2,2,4 - trimethylhexane 1,6 - diisocyanate, ethylene diisocyanate, dodecane 1,12 - diisocyanate, and mixtures of the aforementioned polyisocyanates. Suitable polyisocyanate parent structures may be polyisocyanate prepolymers having urethane structural units obtained by the reaction of a polyol with a stoichiometric excess of the aforementioned aliphatic polyisocyanates. Particularly preferred polyisocyanate parent structures are hexamethylene diisocyanate and / or its biuret dimer and / or allophanate dimer and / or isocyanurate trimer and / or its uretdione, and further mixtures of the aforementioned polyisocyanate parent structures. Particularly preferred polyisocyanate parent structures are hexamethylene diisocyanate and / or its isocyanurate trimer (optionally accompanied by its uretdione). 【0094】 Suitable alicyclic polyisocyanates are preferably substituted or unsubstituted alicyclic polyisocyanates such as isophorone diisocyanate, cyclobutane 1,3 - diisocyanate, cyclohexane 1,3 - diisocyanate, cyclohexane 1,4 - diisocyanate, methylcyclohexyl diisocyanate, hexahydrotoluene 2,4 - diisocyanate, hexahydrotoluene 2,6 - diisocyanate, hexahydrophenylene 1,3 - diisocyanate, hexahydrophenylene 1,4 - diisocyanate, perhydrodiphenylmethane 2,4'-diisocyanate and 4,4'-methylenedicyclohexyl diisocyanate, and mixtures of the aforementioned polyisocyanates. Suitable polyisocyanate parent structures may be polyisocyanates derived from alicyclic polyisocyanates by trimerization, dimerization, urethane formation, biuret formation, uretdione formation and / or allophanate formation, more particularly biuret dimers and / or allophanate dimers and / or isocyanurate trimers. The polyisocyanate parent structure may be a polyisocyanate prepolymer having urethane structural units obtained by reaction of a polyol with a stoichiometric excess of the aforementioned alicyclic polyisocyanates. Particularly preferred alicyclic polyisocyanates are isophorone diisocyanate and 4,4'-methylenedicyclohexyl diisocyanate and / or its biuret dimer and / or its allophanate dimer and / or its isocyanurate trimer. 【0095】 Preferably, component b2) does not contain any silane - modified NCO groups, i.e., none of its NCO groups are preferably reacted with any silane. Preferably, component B) does not contain any NCO - group - containing component(s) having silane - modified NCO groups. 【0096】 Any optional component b3) Optionally, the primer coating-based component B) comprises at least one optional component b3). Any optional component b3) is different from each of components b1) and b2), has at least one hydrolyzable group X, and preferably further has at least one non-hydrolyzable organic residue R and / or T, and is an organosilane component. Any optional component b3) is different from each of components a1) to a3) of component A). Preferably, the component b3) is used as an adhesion promoter. 【0097】 Preferably, at least one organosilane component b3) is a monosilane, has at least two, particularly preferably at least three, hydrolyzable groups X, and / or is at least one bis(silane) preferably having at least four, particularly preferably six, hydrolyzable groups X. 【0098】 Preferably, at least one organosilane b3) has the general formula (I) and / or (II) Si(X) 4-y (R) y (I), Si(X) 3-z (T) z -(RA)-Si(X) 3-z (T) z (II), is an organosilane of wherein, in the case of the general formula (I), X is each independently a hydrolyzable group, preferably each independently selected from O-C 1~4 alkyl, the parameter y is an integer in the range of 1 to 3, but at least 1, preferably exactly 1, and R is a non-hydrolyzable organic residue, preferably an aliphatic residue, preferably having 1 to 10 carbon atoms, and at least one of the residues R optionally contains at least one functional group, and wherein, in the case of the general formula (II), X represents a hydrolyzable group, in each case independently of one another, and preferably, in each case independently of one another, O-C1~4 - selected from -alkyl, RA represents a divalent non-hydrolyzable organic residue, preferably an aliphatic residue, preferably having 1 to 10 carbon atoms, preferably containing no functional groups, the parameter z is in each case an integer in the range of 1 to 3, preferably 01 in each case, and T is a non-hydrolyzable organic residue, preferably an aliphatic residue, preferably having 1 to 10 carbon atoms, different from the residue RA, and optionally containing at least one functional group. 【0099】 Examples of suitable functional groups are in particular thiol groups, amino groups, epoxide groups. 【0100】 Examples of suitable organosilanes are, for example, (3-aminopropyl)trimethoxysilane, (3-aminopropyl)triethoxysilane, N-2-aminoethyl-3-aminopropyltrimethoxysilane, (3-mercaptopropyl)trimethoxysilane, (3-mercaptopropyl)triethoxysilane, (3-glycidyloxypropyl)trimethoxysilane, (3-glycidyloxypropyl)triethoxysilane, bis(2-ethyltrimethoxysilyl)amine, bis(3-propyltrimethoxysilyl)amine, bis(4-butyltrimethoxysilyl)amine, bis(2-ethyltriethoxysilyl)amine, bis(3-propyltriethoxysilyl)amine and / or bis(4-butyltriethoxysilyl)amine. 【0101】 Any component C) Any component C) is a reducing agent component and contains at least one organic solvent c1). Component C) is used to dilute the coating composition to be prepared and for this reason contains at least one organic solvent c1) and preferably consists of at least one organic solvent c1). Examples of such organic solvents include those already mentioned above in connection with components a1) and b1). Component C) may contain a plurality of organic solvents c1). At least one organic solvent c1) may be the same as or different from at least one organic solvent a1) and / or b1). When a plurality of organic solvents are used as a1) and / or b1) and / or c1), a1) and / or b1) and / or c1) are all partially identical and partially different. 【0102】 Layer L2 and basecoat composition The second coating layer L2 is applied on the first coating layer L1, and the layer L2 is obtained from a basecoat composition (intermediate coating composition). 【0103】 Any type of basecoat composition can be used, for example, 1K or 2K basecoat compositions, preferably 1K compositions, which can be solvent-based or water-based and may contain coloring pigments and / or effect pigments. Preferably, the basecoat composition contains at least one film-forming binder having a functional group reactive with respect to NCO groups, preferably at least one polymer, more preferably at least one polymer. Optionally, the basecoat composition may contain at least one crosslinking agent, preferably selected from melamine formaldehyde resins and / or preferably blocked polyisocyanates, especially when at least the film-forming binder is an externally crosslinking polymer. 【0104】 Layer L3, clearcoat composition and clearcoat system The third coating layer L3 is applied on the second coating layer L2, and the layer L3 is obtained from a clearcoat composition. 【0105】 Any kind of clearcoat composition, for example, a 1K or 2K clearcoat composition, preferably a 2K clearcoat composition, i.e., suitable for preparing a clearcoat composition, preferably containing at least two components, for example, component D) and component E) defined below and optionally at least one further component F) defined below, can be used. Preferably, a solvent-based clearcoat composition is used. Preferably, the clearcoat composition contains at least one film-forming binder having a functional group reactive with an NCO group, preferably at least one polymer, more preferably at least one polymer. Optionally, the clearcoat composition may contain at least one crosslinking agent selected preferably from melamine formaldehyde resins and / or preferably blocked polyisocyanates, especially when the at least one film-forming binder is an externally crosslinkable polymer. However, especially when the clearcoat composition is obtained from a clearcoat system, the at least one crosslinking agent may be a polyisocyanate having free NCO groups. 【0106】 Preferably, the clearcoat composition used to prepare layer L3 is obtained from a clearcoat system, for example, a 2K clearcoat system containing at least two components D) and E) and optionally at least one further component F), the said components being different from each other and separated from each other. The clearcoat system is a two-component (2K) or multi-component coating system. Separated from each other in this context means that the components D), E) and optionally F) of the coating system can be stored separately until they are mixed with each other to prepare the primer coating composition. When the coating system is a two-component coating system, it preferably consists of components D) and E). When at least two components D) and E) are mixed and the resulting composition is applied to the surface of the substrate, a polyurethane or polyurethane-based coating film is preferably formed by the reaction of the OH groups of at least one constituent d2) with the isocyanate groups of at least one constituent e2) and optionally e3). These constituents are defined below. 【0107】 The preparation of the clear coat composition can be carried out using conventional and known preparation and mixing methods and mixing units, or using conventional dissolvers and / or stirrers. 【0108】 Preferably, the clear coat composition is a solvent-based, i.e., an organic solvent(s)-based coating composition. The term "solvent-based" has already been defined herein and is applied similarly here. 【0109】 The clear coat composition preferably contains at most 65% by mass, more preferably at most 60% by mass, even more preferably at most 55% by mass, still more preferably at most 50% by mass, also more preferably at most 48% by mass, particularly at most 45% by mass or at most 40% by mass, or at most 35% by mass or at most 30% by mass of the organic solvent(s) fraction, and these mass percentages are in each case relative to the total mass of the coating composition. Any conventional organic solvent known to those skilled in the art can be used as the organic solvent, i.e., the solvent defined as components a1), b1) and optionally c1) above. Examples of organic solvents that can be used have already been described above in connection with components a1), b1) and c1). 【0110】 Preferably, the clear coat composition has a total solids content of >35% by mass, more preferably >40% by mass, even more preferably >45% by mass, also more preferably >50% by mass, and these mass percentages are in each case relative to the total mass of the coating composition. 【0111】 The total solids content of the clear coat composition is preferably in the range of >35 - 75% by mass, more preferably >40 - 70% by mass, even more preferably >45 - 65% by mass, still more preferably >48 - 60% by mass, and these mass percentages are in each case relative to the total mass of the coating composition. The total solids content, in other words the non-volatile fraction, is determined according to the method described below. 【0112】 Preferably, the clear coat composition is obtained by mixing component D) and component E) in a mass ratio of component D) / component E) in the range of 4:1 to 1:2. More preferably, the mixing is carried out at a mass ratio in the range of 3:1 to 1:1, even more preferably in the range of 2:1 to 1:1, particularly at a mass ratio of 1:1. 【0113】 Preferably, both component D) and component E) of the coating system and any optional component F) do not contain water or are essentially free of water. The same applies to the coating composition obtained therefrom. In the context of the present invention, the term "water-free" preferably means that there is no water at all. In the context of the present invention, the term "essentially water-free" preferably means that there is essentially no water. This means that at least no water is intentionally added to any of component D), component E) and optionally F) used according to the present invention, nor to the coating composition obtained therefrom. However, it does not exclude the presence of residues of water formed during the preparation of any of the constituents used to prepare component D), component E) and optionally F) according to the present invention. Preferably, the amount of any water present in each of component D), component E) and optionally F) is less than 1% by weight, more preferably less than 0.5% by weight, even more preferably less than 0.1% by weight, still more preferably less than 0.05% by weight, yet more preferably less than 0.01% by weight, particularly less than 0.005% by weight or less than 0.001% by weight, and these percentages by weight are in each case relative to the total weight of component D), component E) or optionally F). Preferably, both component D) and component E) of the coating system and optionally component F) are based on a solvent system, i.e. an organic solvent(s). Thus, preferably, the coating system is not an aqueous system, i.e. an aqueous coating system. 【0114】 Preferably, both components D) and E) of the clear coating system and optionally F) are transparent, i.e., clear. Preferably, the clear coat composition obtained therefrom is of course also transparent, i.e., clear. In particular, none of components D), E) and optionally F) of the coating system contains any pigment and / or filler, especially pigments and / or fillers that impart color and / or effect. Preferably, the same applies of course to the clear coat composition. 【0115】 Component D) Component D) preferably contains at least constituent d2) and optionally at least one constituent d1), which are different from each other, but may further contain additional optional constituents, such as d3), d4) and / or d5), which are different from each other and from both d1) and d2). 【0116】 Preferably, component D) of the clear coat system has a total solids content of > 30% by mass, preferably > 35% by mass, more preferably > 40% by mass, even more preferably > 45% by mass, based on the total mass of component D). The total solids content of component D) of the coating system is preferably in the range of > 35 - 60% by mass, more preferably 40 - 55.0% by mass, based on the total mass of component D). The total solids content, in other words the non-volatile fraction, is determined according to the method described below. 【0117】 Optional constituent d1) Optional constituent d1) is at least one organic solvent. Examples of such organic solvents include those already mentioned above in connection with constituents a1), b1) and c1). Component D) may contain a plurality of organic solvents d1). At least one organic solvent d1) may be the same as or different from at least one organic solvent a1) and / or b1) and / or c1). When a plurality of organic solvents are used as a1) and / or b1) and / or c1) and / or d1), a1), b1) and / or c1) and / or d1) are all partially the same and partially different. 【0118】 Constituent d2) and optional constituent d3) Constituent d2) is at least one OH-functional (meth)acrylic polymer. Optional constituent d3) is also at least one OH-functional (meth)acrylic polymer, but is different from d2). Preferably, both d2) and d3) are present in component D). At least one OH-functional (meth)acrylic polymer d3) has a glass transition temperature (T g ) lower than that of at least one OH-functional (meth)acrylic polymer d2). g ) The amount of constituent d2) in component D) exceeds the amount of constituent d3), that is, the (meth)acrylic polymer d2) having a higher T g (higher than (meth)acrylic polymer d3)) is present in component D) in a higher amount than (meth)acrylic polymer d3) (when d3) is present). By using d2) and d3) in particular in this way, it has been found that the packaging stability of the resulting clear coat prepared by the production of component D) is improved. T g is measured according to the method disclosed in the section "Method". 【0119】 Preferably, at least one OH-functional (meth)acrylic polymer d2) present in component D) of the clear coat system has a glass transition temperature (T g ) in the range of +10°C to +75°C, preferably +15°C to +70°C, more preferably +20°C to +65°C, still more preferably +25°C to +60°C, even more preferably +30°C to +55°C, most preferably +35°C or +40°C to +50°C. 【0120】 Preferably, at least one OH-functional (meth)acrylic polymer d3) optionally present in component D) of the clear coat system has a glass transition temperature (T g ) in the range of -70°C to <+10°C, preferably -60°C to +5°C, more preferably -50°C to 0°C, still more preferably -45°C to 0°C, even more preferably -40°C to 0°C, yet more preferably -35°C or -30°C to -5°C, most preferably -25°C or -5°C. 【0121】 The OH-functional (meth)acrylic polymers d2) and d3) each preferably contain on average two or more OH groups. Preferably, each of the OH-functional (meth)acrylic polymers d2) and d3) has an OH value of 30 to 400 mg KOH / g, more specifically 100 to 300 mg KOH / g. 【0122】 Preferably, each of the components d2) and d3) has a mass average molecular weight M, as measured by gel permeation chromatography (GPC) relative to polystyrene standards, preferably between 800 and 100,000 g / mol, more specifically between 1,000 and 75,000 g / mol. w having. 【0123】 The term "(meth)acrylic polymer" in each case includes both homopolymers and copolymers, but preferably means copolymers. 【0124】 In the context of the present invention, the term “(meth)acrylic” or “(meth)acrylate” or “(meth)acrylic acid” in each case includes the meanings of “methacrylic” and / or “acrylic”, “methacrylic acid” and / or “acrylic acid” or “methacrylate” and / or “acrylate”. Thus, generally, a “(meth)acrylic acid copolymer” is formed only from “acrylic acid monomer” only, “methacrylic acid monomer” or “acrylic acid and methacrylic acid monomer” only. However, the “(meth)acrylic acid copolymer” may also contain polymerizable monomers other than acrylic acid and / or methacrylic acid monomers (for example, styrene, etc.). In other words, the (meth)acrylic polymer may consist only of acrylic acid and / or methacrylic acid monomer units, but it is not necessarily so. Note that the notations “(meth)acrylate polymer or copolymer” or “(meth)acrylic polymer or copolymer” mean that the polymer / copolymer (polymer skeleton / backbone) is mainly formed from monomers having a (meth)acrylate group, that is, more than 50% or more than 75% of the monomer units are used. Therefore, in the preparation of a (meth)acrylic acid copolymer, preferably, more than 50% or more than 75% of the monomers have a (meth)acrylate group. However, the use of further monomers as comonomers (for example, copolymerizable vinyl monomers (for example, styrene)) for its preparation is not excluded. 【0125】 For the introduction of OH functionality, hydroxyl-containing monomers comprising hydroxyalkyl esters of acrylic or methacrylic acid can be used. Non-limiting examples of hydroxyl-functional monomers include hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, hydroxyhexyl (meth)acrylate, propylene glycol mono(meth)acrylate, 2,3-dihydroxypropyl (meth)acrylate, pentaerythritol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate, polyethylene glycol mono(meth)acrylate, reaction products thereof with epsilon-caprolactone, and other hydroxyalkyl (meth)acrylates having branched or straight-chain alkyl groups of up to about 10 carbons, and mixtures thereof. The term "(meth)acrylate" refers to either or both methacrylate and acrylate esters. Generally, at least about 5% by weight of the hydroxyl-functional monomer is preferably included in the polymer. Hydroxyl groups on vinyl polymers, such as acrylic polymers, can be produced by other means, such as by ring-opening of glycidyl groups, such as from polymerized glycidyl methacrylate, with an organic acid or an amine. 【0126】 Hydroxyl functionality can also be introduced via thio-alcohol compounds including, but not limited to, 3-mercapto-1-propanol, 3-mercapto-2-butanol, 11-mercapto-1-undecanol, 1-mercapto-2-propanol, 2-mercaptoethanol, 6-mercapto-1-hexanol, 2-mercaptobenzyl alcohol, 3-mercapto-1,2-propanediol, 4-mercapto-1-butanol, and combinations thereof. Any of these methods can be used to prepare useful hydroxyl-functional (meth)acrylic polymers. 【0127】 Examples of suitable comonomers include, but are not limited to, α,β-ethylenically unsaturated monocarboxylic acids containing 3 to 5 carbon atoms, such as acrylic acid, methacrylic acid, and crotonic acid, and alkyl and cycloalkyl esters, nitriles, and amides of acrylic acid, methacrylic acid, and crotonic acid, α,β-ethylenically unsaturated dicarboxylic acids containing 4 to 6 carbon atoms and anhydrides, monoesters, and diesters of these acids, vinyl esters, vinyl ethers, vinyl ketones, and aromatic or heterocyclic aliphatic vinyl compounds. Representative examples of suitable esters of acrylic acid, methacrylic acid, and crotonic acid include, but are not limited to, saturated aliphatic alcohols containing 1 to 20 carbon atoms, such as methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, tert-butyl, hexyl, 2-ethylhexyl, dodecyl, 3,3,5-trimethylhexyl, stearyl, lauryl, cyclohexyl, alkyl-substituted cyclohexyl, alkanol-substituted cyclohexyl, such as 2-tert-butyl and 4-tert-butylcyclohexyl, 4-cyclohexyl-1-butyl, 2-tert-butylcyclohexyl, 4-tert-butylcyclohexyl, 3,3,5,5,-tetramethylcyclohexyl, tetrahydrofurfuryl, and isobornyl acrylate, methacrylate, and crotonate esters from the reaction, unsaturated dicarboxylic acids and anhydrides, such as fumaric acid, maleic acid, itaconic acid and anhydrides and alcohols, such as methanol, ethanol, propanol, isopropanol, butanol, isobutanol, tert-butanol and their monoesters and diesters, such as maleic anhydride, dimethyl maleate and monohexyl maleate, vinyl acetate, vinyl propionate, vinyl ethyl ether, and vinyl ethyl ketone, styrene, a-methylstyrene, vinyltoluene, 2-vinylpyrrolidone, and p-tert-butylstyrene. 【0128】 (Meth)acrylic polymers may be prepared using conventional techniques, for example by heating the monomers in the presence of a polymerization initiator and optionally a chain transfer agent. The polymerization may be carried out, for example, in solution. Typical initiators are organic peroxides such as dialkyl peroxides, for example di-t-butyl peroxide, peroxy esters such as t-butyl peroxy 2-ethylhexanoate, and t-butyl peracetate, peroxydicarbonates, diacyl peroxides, hydroperoxides such as t-butyl hydroperoxide, and peroxyketals, azo compounds such as 2,2’-azobis(2-methylbutanenitrile) and 1,1’-azobis(cyclohexanecarbonitrile), and combinations thereof. Typical chain transfer agents are mercaptans such as octyl mercaptan, n- or tert-dodecyl mercaptan, halogenated compounds, thiosalicylic acid, mercaptoacetic acid, mercaptoethanol and other thiol alcohols already mentioned, and dimerized alpha-methylstyrene. 【0129】 The polymerization reaction is typically carried out at a temperature of about 20°C to about 200°C. The reaction may conveniently be carried out at a temperature at which the solvent or solvent mixture refluxes, although, if appropriately controlled, a temperature below the reflux temperature may be maintained. The initiator should be selected according to the temperature at which the reaction is carried out such that the half-life of the initiator at that temperature is preferably about 30 minutes or less. Further details of addition polymerization in general and the polymerization of mixtures containing (meth)acrylate monomers are readily available in the polymer art. Generally, the solvent or solvent mixture is heated to the reaction temperature and the monomer(s) and initiator(s) are added at a controlled rate over a period, usually 2 to 6 hours. A chain transfer agent or additional solvent may also be supplied at a controlled rate during this time. The temperature of the mixture is then maintained for a period to complete the reaction. Optionally, an additional initiator may be added to ensure complete conversion. 【0130】 Constituent d2) is preferably present in component D) in an amount in the range of 5.0% to 85.0% by mass based on the total mass of component (D). More preferably, constituent d2) is present in component D) in an amount in the range of 10.0% to 80.0% by mass, still more preferably 15.0% to 75.0% by mass, and these mass percentages are in each case based on the total mass of component D). 【0131】 Optional constituent d3) is preferably present in component D) in an amount in the range of 5.0% to 85.0% by mass based on the total mass of component (D). More preferably, constituent d3) is present in component D) in an amount in the range of 10.0% to 80.0% by mass, still more preferably 15.0% to 75.0% by mass, and these mass percentages are in each case based on the total mass of component D). 【0132】 Optional constituent d4) Optional constituent d4) is preferably at least one catalyst d4) which is suitable for crosslinking of NCO groups and is preferably selected from organotin catalysts. Catalyst d4) may be the same as or different from catalyst a3). Preferably, catalyst d4) and a3) are the same. 【0133】 Component D) may contain at least one further organometallic catalyst other than catalyst d4), for example an organobismuth catalyst. However, preferably, when at least one further organometallic catalyst such as an organobismuth catalyst is additionally present in component D), its amount is less than the amount of catalyst d4). However, more preferably, component D) does not contain any other organometallic catalyst other than catalyst d4), and in particular does not contain any organobismuth catalyst. 【0134】 Preferably, at least one catalyst d4) suitable for crosslinking the NCO groups, especially the constituent e2) of component E), is present in component D) of the clearcoat system in an amount in the range of 0.001 to 3.00% by mass, preferably 0.01 to 2.50% by mass, more preferably 0.05 to 2.00% by mass, even more preferably 0.10 to 1.50% by mass, still more preferably 0.20 to 1.25% by mass, and most preferably 0.30 to 1.00% by mass, and these mass percentages are based on the total mass of component D). 【0135】 The catalyst d4) is preferably selected from organotin catalysts. Examples of organotin catalysts are DOTL (dioctyltin dilaurate) and DBTL (dibutyltin dilaurate). DOTL is particularly preferred. 【0136】 Any constituent d5) Preferably, component D) of the clearcoat system further comprises at least one catalyst d5) suitable for crosslinking preferably Si-containing functional groups, and the catalyst d5) is different from each of constituents d1) to d4). The catalyst d5) may be the same as or different from catalysts a4) and a4a). 【0137】 Preferably, at least one catalyst d5) is suitable for crosslinking the Si-containing functional groups present in constituent e2) of component E). 【0138】 Preferably, component D) of the clearcoat system contains at least one catalyst d5) in an amount in the range of 0.01 to 6.00% by mass, preferably 0.10 to 5.50% by mass, more preferably 0.40 to 5.00% by mass, even more preferably 0.70 to 4.50% by mass, still more preferably 1.00 to 4.00% by mass, and most preferably 1.10 to 3.75% by mass, and these mass percentages are based on the total mass of component D). 【0139】 Preferably, at least one catalyst d5) is a phosphorus-containing catalyst and / or a phosphorus-containing and nitrogen-containing catalyst. As the catalyst d5), a plurality of, for example, two different catalysts can be used. 【0140】 Examples of suitable phosphorus-containing catalysts are preferably substituted phosphonic acid diesters and diphosphonic acid diesters selected from the group consisting of acyclic phosphonic acid diesters, cyclic phosphonic acid diesters, acyclic diphosphonic acid diesters, and cyclic diphosphonic acid diesters. However, more specifically, as at least one catalyst d5), preferably selected from the group consisting of acyclic phosphoric acid diesters and monoesters, and cyclic phosphoric acid diesters and monoesters, and in each case, substituted phosphoric acid monoesters and phosphoric acid diesters, for example, amine adducts of phosphoric acid monoesters and diesters, are used. 【0141】 Examples of such amine adducts are the corresponding amine-blocked phosphoric acid esters, among which, more specifically, amine-blocked ethylhexyl phosphate and amine-blocked phenyl phosphate, and very preferably, amine-blocked bis(2-ethylhexyl) phosphate. Examples of amines that block phosphoric acid esters are, in particular, tertiary amines, and examples include bicyclic amines, for example, diazabicyclooctane (DABCO), diazabicyclononene (DBN), diazabicycloundecene (DBU), dimethyldodecylamine, or triethylamine. Particularly preferred for blocking phosphoric acid esters is the use of tertiary amines that ensure high catalyst activity under curing conditions. Certain amine-blocked phosphoric acid catalysts are also commercially available (for example, Nacure types from King Industries, for example, Nacure® 4167). 【0142】 Preferably, at least one catalyst d5) is selected from phosphorus-containing organic components, more preferably selected from acyclic phosphoric acid diesters, acyclic phosphoric acid monoesters, cyclic phosphoric acid diesters and cyclic phosphoric acid monoesters, and each of the aforementioned phosphoric acid diesters and monoesters may optionally be present in the form of an adduct with at least one amine (i.e., blocked with at least one amine), but preferably is not blocked by any amine, preferably at least one tertiary amine, even more preferably, at least two catalysts are present as at least one catalyst d5), and both of them are selected from acyclic phosphoric acid diesters, acyclic phosphoric acid monoesters, cyclic phosphoric acid diesters and cyclic phosphoric acid monoesters, but at least one of these at least two catalysts is present in the form of its amine adduct, and the other one of these at least two catalysts is not present as an amine adduct (i.e., in an unblocked form). 【0143】 Preferably, at least two types of catalysts d5) are present, one catalyst is not present in the form of an amine adduct such as 2-ethylhexyl acid phosphate, preferably present in an amount in the range of 0.05 to 3.5% by mass, more preferably 0.10 to 3.0% by mass, still more preferably 0.50 to 2.0% by mass or ~1.5% by mass, and one catalyst is present in the form of an amine adduct, preferably present in an amount in the range of 1.0 to 4.0% by mass, more preferably 1.0 to 3.0% by mass. Preferably, the amount of the catalyst present in the form of an amine adduct exceeds the amount of the catalyst not present in the form of an amine adduct. 【0144】 Preferably, at least 2-ethylhexyl acid phosphate is used as at least one catalyst d5), especially not present in the form of an amine adduct, i.e., not present in any amine-blocked form, as at least one catalyst d5). The term "2-ethylhexyl acid phosphate" includes both monoethylhexyl acid phosphate and diethylhexyl acid phosphate. 【0145】 Further components Component D) may optionally contain one or more further components. Component D) may contain one or more commonly used additives depending on the desired application. For example, it may contain at least one additive selected from the group consisting of reactive diluents, light stabilizers, antioxidants, degassing agents, emulsifiers, slip additives, polymerization inhibitors, plasticizers, free radical polymerization initiators, adhesion promoters, flow regulators, film-forming aids, flame retardants, corrosion inhibitors, desiccants, biocides, thickeners, wetting agents, leveling agents and / or matting agents. These can be used in known and customary proportions. Preferably, their content relative to the total mass of the coating composition obtained by mixing components D), E) and optionally F) is from 0.01 to 20.0% by mass, more preferably from 0.05 to 15.0% by mass, particularly preferably from 0.1 to 10.0% by mass, even more preferably from 0.1 to 7.5% by mass, especially from 0.1 to 5.0% by mass, and most preferably from 0.1 to 2.5% by mass, and these mass percentages are in each case relative to the total mass of the coating composition. 【0146】 Component D) may further contain one or more further (meth)acrylic polymers which are different from both d2) and d3), and these may likewise be OH-functional, but do not necessarily have to be. Component D) may contain one or more further film-forming polymers which are suitable as binder components such as polyesters and / or polyurethanes. Suitable polyesters are described, for example, in EP-A-0 994 117 and EP-A-1 273 640. The polyurethane polyol is preferably prepared by reaction of a polyester polyol prepolymer with a suitable di- and / or polyisocyanate and is described, for example, in EP-A-1 273 640. 【0147】 Component E) Component E) preferably contains at least two components e2) and optionally at least components e1) which are different from one another, but may further contain any further components which are different from one another and from e1) and e2). 【0148】 Preferably, the clear coat-based component E) has a total solids content of >40% by mass, more preferably >45% by mass, even more preferably >50% by mass, and still more preferably >55% by mass, where these % by mass are in each case relative to the total mass of component E). The total solids content of the clear coat-based component E) is preferably in the range of 45 to 100% by mass, more preferably in the range of 50 to <100% by mass, even more preferably in the range of 55 to <100% by mass, where these % by mass are in each case relative to the total mass of component E). The total solids content, in other words the non-volatile fraction, is determined according to the method described below. 【0149】 Any constituent e1) Any constituent e1) is at least one organic solvent. Examples of such organic solvents include those already mentioned above in connection with constituents a1), b1), c1), and d1). Component E) may contain a plurality of organic solvents e1). At least one organic solvent e1) may be the same as or different from at least one of the organic solvents a1), b1), c1), and d1). When a plurality of organic solvents are used as a1), b1), c1), d1), and / or e1), a1) and b1), c1), d1), and / or e1) are all partially the same and partially different. 【0150】 Constituent e2) Constituent e2) is an organic constituent having on average two or more NCO groups, and preferably at least a part of the NCO groups has reacted with at least one organosilane before constituent e2) is incorporated into component E). 【0151】 Examples of component e2) are disclosed, for example, in WO2009 / 077181A1, WO2010 / 139375A1, WO2010 / 063332A1, WO2014 / 086530A1 and WO2014 / 086529A1. Component e2) may be the same as or different from component b2). In particular, when e2) has undergone at least partial silanization as described above, e2) is different from b2). 【0152】 Preferably, at least one component e2) of the clear coat system component E) has the formula (I) -NR-(X-SiR’’ x (OR’) 3-x ) (I), at least one structural unit of and / or, preferably and, the formula (II) -N(X-SiR’’ x (OR’) 3-x ) n (X’-SiR’’ y (OR’) 3-y ) m (II), at least one structural unit of and has wherein R is hydrogen, alkyl, cycloalkyl, aryl or aralkyl, and the carbon chain may be interrupted by non-adjacent oxygen, sulfur or NR a groups, and this R a is alkyl, cycloalkyl, aryl or aralkyl,[[]]END]] each R’ is, independently of one another, hydrogen, alkyl or cycloalkyl, and the carbon chain may be interrupted by non-adjacent oxygen, sulfur or NR a groups, preferably each R’ is ethyl and / or methyl,[[]]END]] each X, X’ is, independently of one another, a straight-chain and / or branched alkylene or cycloalkylene group having 1 to 20 carbon atoms, preferably each X, X’ is an alkylene group having 1 to 4 carbon atoms,[[]]END]] Each R'' is independently alkyl, cycloalkyl, aryl or aralkyl, and the carbon chain may be interrupted by non-adjacent oxygen, sulfur or NR a groups, and preferably each R'' is an alkyl group, more particularly having from 1 to 6 C atoms, n is a parameter from 0 to 2, m is a parameter from 0 to 2, m + n is 2, and x, y are parameters from 0 to 2. 【0153】 Each preferred alkoxy group (OR') may be the same or different, but what is crucial for the structure of the group is the extent to which they affect the reactivity of the hydrolyzable silane group. Preferably, R' is an alkyl group, more particularly having from 1 to 6 carbon atoms. Groups R' which increase the reactivity of the silane group, i.e. which correspond to good leaving groups, are particularly preferred. Thus, a methoxy group is more preferred than an ethoxy group, and an ethoxy group is more preferred than a propoxy group. Thus, particularly preferred is R' = ethyl and / or methyl, more particularly methyl. The reactivity of the organofunctional silane can also be considerably further influenced by the length of the spacers X, X' between the silane functional group and the organic functional group which plays a role in the reaction with the component to be modified. Examples thereof which can be mentioned include "alpha" silanes available from Wacker, in which a methylene group is present between the Si atom and the functional group instead of a propylene group (which is present in the case of "gamma" silanes). 【0154】 In component e2), preferably between 10 and 80 mol%, preferably between 15 and 70 mol%, more preferably between 20 and 50 mol%, and even more preferably between 25 and 40 mol% of the isocyanate groups originally present have reacted with at least one organosilane to form structural unit (I) and / or (II), more preferably forming structural units (I) and (II). 【0155】 Furthermore, it is preferable that the total amount of structural unit (I) is between 3 and 90 mol%, more preferably between 5 and 70 mol% (in each case based on the total of structural units (I) and (II)), and the total amount of structural unit (II) is between 97 and 10 mol%, more preferably between 95 and 30 mol% (in each case based on the total of structural units (I) and (II)), for constituent e2). 【0156】 At least one organic constituent e2) having on average two or more NCO groups functions as the parent structure of constituent e2) before reaction with at least one silane and represents a di- and / or polyisocyanate at this stage before reaction with at least one silane. Preferably, the at least one di- and / or polyisocyanate is an aromatic, aliphatic, alicyclic and / or heterocyclic di- and / or polyisocyanate, particularly aliphatic and acyclic. 【0157】 At least one organic constituent e2) preferably has an alicyclic parent structure and / or a parent structure derived from an alicyclic polyisocyanate by trimerization, dimerization, urethane formation, biuret formation, uretdione formation and / or allophanate formation, and constituent e2) has at least one structural unit of formula (I) and / or (II). Alternatively or additionally, at least one organic constituent e2) preferably has an acyclic aliphatic parent structure and / or a parent structure derived from an acyclic aliphatic polyisocyanate by trimerization, dimerization, urethane formation, biuret formation, uretdione formation and / or allophanate formation, and constituent e2) has at least one structural unit of formula (I) and / or (II). 【0158】 Most preferably, at least one organic constituent e2) has an acyclic aliphatic parent structure and / or a parent structure derived from an acyclic aliphatic polyisocyanate by trimerization, dimerization, urethane formation, biuret formation, uretdione formation and / or allophanate formation, and constituent e2) has at least one structural unit of formula (I) and / or (II). Trimers, i.e., isocyanurates, are particularly preferred. 【0159】 The acyclic aliphatic polyisocyanate fulfilling the role of the parent structure is preferably a substituted or unsubstituted aliphatic polyisocyanate known per se. Examples include tetramethylene 1,4 - diisocyanate, hexamethylene 1,6 - diisocyanate, 2,2,4 - trimethylhexane 1,6 - diisocyanate, ethylene diisocyanate, dodecane 1,12 - diisocyanate, and mixtures of the above polyisocyanates. 【0160】 More preferably, the polyisocyanate parent structure is a polyisocyanate derived from such acyclic aliphatic polyisocyanates by trimerization, dimerization, urethane formation, biuret formation, uretdione formation and / or allophanate formation, more particularly a biuret dimer and / or an allophanate dimer and / or an isocyanurate trimer. The polyisocyanate parent structure may also be a polyisocyanate prepolymer having urethane structural units obtained by the reaction of a polyol with a stoichiometric excess of the above acyclic aliphatic polyisocyanate. This type of polyisocyanate prepolymer is described, for example, in US - A - 4,598,131. Particularly preferred polyisocyanate parent structures are hexamethylene diisocyanate and / or its biuret dimer and / or allophanate dimer and / or isocyanurate trimer and / or its uretdione, and furthermore mixtures of the above polyisocyanate parent structures. Particularly preferred polyisocyanate parent structures are hexamethylene diisocyanate and / or its isocyanurate trimer (optionally accompanied by its uretdione). 【0161】 The alicyclic polyisocyanate used as the parent structure is preferably a substituted or unsubstituted alicyclic polyisocyanate known per se. Examples of preferred polyisocyanates are isophorone diisocyanate, cyclobutane 1,3 - diisocyanate, cyclohexane 1,3 - diisocyanate, cyclohexane 1,4 - diisocyanate, methylcyclohexyl diisocyanate, hexahydrotoluene 2,4 - diisocyanate, hexahydrotoluene 2,6 - diisocyanate, hexahydrophenylene 1,3 - diisocyanate, hexahydrophenylene 1,4 - diisocyanate, perhydrodiphenylmethane 2,4'-diisocyanate, 4,4'-methylenedicyclohexyl diisocyanate (e.g., Desmodur® W from Bayer AG) and mixtures of the aforementioned polyisocyanates. Additionally preferred polyisocyanate parent structures are polyisocyanates derived from such alicyclic polyisocyanates by trimerization, dimerization, urethane formation, biuret formation, uretdione formation and / or allophanate formation, more particularly biuret dimers and / or allophanate dimers and / or isocyanurate trimers. The polyisocyanate parent structure may also be a polyisocyanate prepolymer having urethane structural units obtained by the reaction of a polyol with a stoichiometric excess of the above - mentioned alicyclic polyisocyanate. Such polyisocyanate prepolymers are described, for example, in US - A - 4,598,131. Particularly preferred alicyclic polyisocyanates are isophorone diisocyanate and 4,4'-methylenedicyclohexyl diisocyanate and / or their biuret dimers and / or their allophanate dimers and / or their isocyanurate trimers. 【0162】 Before being incorporated into component E), at least one silane used in the reaction with at least one organic constituent e2) having on average two or more NCO groups is preferably of formula (Ia) H - NR-(X - SiR’’ x (OR’) 3-x ) (Ia) at least one compound of and / or a compound of formula (IIa) HN(X-SiR’’ x (OR’) 3-x ) n (X’-SiR’’ y (OR’) 3-y ) m (IIa) at least one compound of wherein the substituents have the definitions given above including the preferred definitions. wherein the substituents have the definitions given above including the preferred definitions. 【0163】 Preferred compounds (Ia) are aminoalkyltrialkoxysilanes, for example, preferably 2-aminoethyltrimethoxysilane, 2-aminoethyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 4-aminobutyltrimethoxysilane, 4-aminobutyltriethoxysilane. Particularly preferred compounds (Ia) are N-(2-(trimethoxysilyl)ethyl)alkylamine, N-(3-(trimethoxysilyl)propyl)alkylamine, N-(4-(trimethoxysilyl)butyl)alkylamine, N-(2-(triethoxysilyl)ethyl)alkylamine, N-(3-(triethoxysilyl)propyl)alkylamine and / or N-(4-(triethoxysilyl)butyl)alkylamine. Especially preferred is N-(3-(trimethoxysilyl)propyl)butylamine. These types of aminosilanes are available, for example, from DEGUSSA under the trade name DYNASYLAN® or from OSI under the trade name Silquest®. 【0164】 Preferred compounds (IIa) are bis(2-ethyltrimethoxysilyl)amine, bis(3-propyltrimethoxysilyl)amine, bis(4-butyltrimethoxysilyl)amine, bis(2-ethyltriethoxysilyl)amine, bis(3-propyltriethoxysilyl)amine and / or bis(4-butyltriethoxysilyl)amine. Particularly preferred is bis(3-propyltrimethoxysilyl)amine. These types of aminosilanes are available, for example, from DEGUSSA under the trade name DYNASYLAN® or from OSI under the trade name Silquest®. 【0165】 Optional component e3) The optionally present component e3) has, on average, two or more NCO groups and is an organic component different from e2). In particular, when component e2) has, on average, two or more NCO groups, at least some of these NCO groups have reacted with at least one organosilane before component e2) is incorporated into component E), and the optionally present component e3) does not contain any silane-modified NCO groups. 【0166】 The optionally present component e3) may be the same as or different from component b2). Preferably, component e3) has, on average, more than two NCO groups. 【0167】 Preferably, at least one organic component e3) optionally present in component E) has a parent structure derived from an aliphatic or alicyclic structure and / or an aliphatic or alicyclic polyisocyanate by trimerization, dimerization, urethane formation, biuret formation, uretdione formation and / or allophanate formation. Trimers of IPDI (isophorone diisocyanate) and / or HDI (hexamethylene diisocyanate), i.e., isocyanurates, are particularly preferred. 【0168】 Suitable aliphatic polyisocyanates are preferably substituted or unsubstituted aliphatic polyisocyanates such as tetramethylene 1,4 - diisocyanate, hexamethylene 1,6 - diisocyanate, 2,2,4 - trimethylhexane 1,6 - diisocyanate, ethylene diisocyanate, dodecane 1,12 - diisocyanate, and mixtures of the aforementioned polyisocyanates. A suitable polyisocyanate parent structure may be a polyisocyanate prepolymer having urethane structural units obtained by the reaction of a polyol with a stoichiometric excess of the aforementioned aliphatic polyisocyanates. Particularly preferred polyisocyanate parent structures are hexamethylene diisocyanate and / or its biuret dimer and / or allophanate dimer and / or isocyanurate trimer and / or its uretdione, and furthermore mixtures of the aforementioned polyisocyanate parent structures. Particularly preferred polyisocyanate parent structures are hexamethylene diisocyanate and / or its isocyanurate trimer (optionally accompanied by its uretdione). 【0169】 Suitable alicyclic polyisocyanates are preferably substituted or unsubstituted alicyclic polyisocyanates such as isophorone diisocyanate, cyclobutane 1,3 - diisocyanate, cyclohexane 1,3 - diisocyanate, cyclohexane 1,4 - diisocyanate, methylcyclohexyl diisocyanate, hexahydrotoluene 2,4 - diisocyanate, hexahydrotoluene 2,6 - diisocyanate, hexahydrophenylene 1,3 - diisocyanate, hexahydrophenylene 1,4 - diisocyanate, perhydrodiphenylmethane 2,4'-diisocyanate and 4,4'-methylenedicyclohexyl diisocyanate, and mixtures of the aforementioned polyisocyanates. Suitable polyisocyanate parent structures may be polyisocyanates derived from alicyclic polyisocyanates by trimerization, dimerization, urethane formation, biuret formation, uretdione formation and / or allophanate formation, more particularly biuret dimers and / or allophanate dimers and / or isocyanurate trimers. The polyisocyanate parent structure may be a polyisocyanate prepolymer having urethane structural units obtained by reaction of a polyol with a stoichiometric excess of the aforementioned alicyclic polyisocyanate. Particularly preferred alicyclic polyisocyanates are isophorone diisocyanate and 4,4'-methylenedicyclohexyl diisocyanate and / or its biuret dimer and / or its allophanate dimer and / or its isocyanurate trimer. 【0170】 Any component F) Any component F) is a reducing agent component and contains at least one organic solvent f1). Component F) is used to dilute the coating composition to be prepared and for this reason contains at least one organic solvent f1) and preferably consists of at least one organic solvent f1). Examples of such organic solvents include those already mentioned above in connection with components a1), b1), c1), d1), and e1). Component F) may contain a plurality of organic solvents f1). At least one organic solvent f1) may be the same as or different from at least one of the organic solvents a1), b1), c1), d1), and e1). When a plurality of organic solvents are used as a1), b1), c1), d1), e1), and / or f1), a1), b1), c1), d1), e1), and / or f1) are all partially the same and partially different. 【0171】 Use A further subject of the invention is a method of use for application onto a substrate selected from a metallic substrate and a plastic substrate, preferably selected from a plastic substrate, more preferably selected from a fiber-reinforced plastic substrate, even more preferably selected from a carbon fiber-reinforced plastic substrate, of a multilayer coating system comprising at least three different coating layers L1, L2, and L3 as defined above and below herein. 【0172】 In this specification, any preferred embodiment described above in connection with the multilayer coating system of the invention, and its preferred embodiment in each case, is also a preferred embodiment of the foregoing use. 【0173】 Method for preparing a multilayer coating system A further subject of the invention is a method comprising at least steps 1) to 3) and optionally 4) for preparing a multilayer coating system on at least one surface of an optionally pre-coated substrate. Preferably, this method is used for the preparation of the multilayer coating system of the invention. 【0174】 All preferred embodiments described above in connection with the multilayer coating system of the present invention and the use of the present invention, and the preferred embodiments in each case, are also preferred embodiments of the method for preparing the aforementioned multilayer coating system. 【0175】 The method includes at least steps (1), (2), (3) and optionally step (4). However, the method may include additional optional steps. 【0176】 Preferably, each of steps 1) to 3) is performed by spray coating. 【0177】 The first, second and third coating films formed on the optionally pre-coated substrate by performing steps 1), 2) and 3) are preferably coating films that are not cured at this stage. Therefore, preferably, both the first coating composition, the second coating composition and the third coating composition are applied wet-on-wet. 【0178】 Step 1) Step 1) relates to at least partially applying a first coating composition to at least one surface of an optionally pre-coated substrate to form a first coating film on said surface, and the first coating composition is a primer coating composition used according to the present invention. 【0179】 Preferably, the method of the present invention further includes step 1a), which is performed after step 1) and before step 2). In said step 1a), the first coating film obtained after step 1) is preferably flash-off for a period of 1 to 20 minutes, more preferably 1.5 to 15 minutes, still more preferably 2 to 12 minutes, even more preferably 5 to 11 minutes, most preferably 8 to 10 minutes, before the second coating composition is applied in step 2). Preferably, step 1a) is performed at a temperature not exceeding 40°C, more preferably in the temperature range of 18 to 30°C. 【0180】 The term "flashing off" in the sense of the present invention means drying, and before curing occurs, at least a part of the solvent and / or water evaporates from the coating film (i.e., from the primer coating layer being formed). Flashing off does not cause curing. 【0181】 Step 2) Step 2) relates to applying at least one base coat composition as at least one second coating composition to the first coating film present on the substrate obtained after Step 1), preferably before curing the first coating film, and forming a second coating film adjacent to the first coating film. 【0182】 Preferably, this method further includes Step 2a) which is carried out after Step 2) and before Step 3). In said Step 2a), preferably for a period of 1 to 20 minutes, more preferably for a period of 1.5 to 15 minutes, still more preferably for a period of 2 to 12 minutes, yet more preferably for a period of 5 to 11 minutes, and most preferably for a period of 8 to 10 minutes, the second coating film obtained after Step 2) is flashed off. Preferably, Step 2a) is carried out at a temperature not exceeding 40°C, more preferably in the temperature range of 18 to 30°C. 【0183】 Step 3) Step 3) relates to applying a clear coat composition as a third coating composition to the second coating film present on the substrate obtained after Step 2), preferably before curing the second coating film, and forming a third coating film which is adjacent to the second coating film and is preferably the outermost coating film of the formed multi-layer coating system. 【0184】 Preferably, the method further includes step 3a) which is carried out after step 3) and before step 4). In said step 3a), the third coating film obtained after step 3) is flash-off, preferably for a period of 1 to 20 minutes, more preferably for a period of 3 to 15 minutes, particularly for a period of 7 to 12 minutes, before performing the curing step 4). Preferably, step 3a) is carried out at a temperature not exceeding 40°C, more preferably in the temperature range of 18 to 30°C. 【0185】 Step 4 In any step 4), the first, second and third coating films are cured together, i.e., cured simultaneously together. Preferably, step 4) is carried out. The cured third coating film preferably represents the outermost layer of the formed multilayer coating system obtained after step 4). 【0186】 Each obtained cured coating film represents a coating layer. Thus, after performing step 4), the first, second and third coating layers are formed on the optionally pre-coated substrate, and the third layer is preferably the outermost layer of the formed multilayer coating system. The first layer L1 is obtained from the first coating film, the second layer L2 is obtained from the second coating film, and the third layer L3 is obtained from the third coating film. 【0187】 Preferably, step 4) is carried out at a temperature in the range of 30 to 180°C, more preferably in the range of 35 to 170°C, even more preferably in the range of 40 to 140°C, and still more preferably in the range of 40 to 130°C, and in each case preferably for a period of 5 to 45 minutes, more preferably for a period of 10 to 40 minutes, particularly for a period of 12.5 to 35 minutes, and most preferably for a period of 15 to 30 minutes. Most preferably, especially when a plastic substrate or a fiber-reinforced plastic substrate is used, step 4) is carried out at a temperature not exceeding 80°C, preferably not exceeding 70°C, more preferably not exceeding 60°C, and even more preferably not exceeding 55°C. The temperature is the substrate temperature in each case and is preferably measured with a thermocouple. 【0188】 Preferably, the cured primer film (layer L1) obtained after performing step 4) has a dry film thickness in the range of 10 to 35 μm. Preferably, the cured base coat film (layer L2) obtained after performing step 4) has a dry film thickness in the range of 12 to 35 μm. Preferably, the cured film (layer L3) obtained after performing step 4) for the top coat, particularly the clear coat, has a dry film thickness in the range of 30 to 60 μm. 【0189】 Kit-of-parts A further subject of the present invention is at least the following, separated from each other A primer coating system used according to the present invention, defined above and below herein, comprising at least two components A) and B) and optionally at least one further component C), and A clear coat composition, preferably a 1K-clear coat composition, or a 2K-clear coat system suitable for preparing a clear coat composition, preferably comprising at least two components D) and E) and optionally at least one further component F), defined above and below herein, clear coat composition A kit-of-parts comprising 【0190】 The kit-of-parts may optionally further comprise a base coat composition or a base coat coating system for providing a base coat composition, but preferably consists of both the primer coating system used in the present invention and a clear coat composition or a clear coat system suitable for preparing a clear coat composition. 【0191】 In this specification, all preferred embodiments described above in connection with the multi-layer coating system of the present invention, and the aforementioned use method and the method for preparing the multi-layer coating system of the present invention, and the preferred embodiments thereof in each case, are also preferred embodiments of the aforementioned kit-of-parts. 【0192】 Method 1. Humidity exposure Humidity exposure is determined according to the high humidity test (96 hours) of GMW14729 (4th edition, August 2020). 【0193】 2. Tape Adhesion Tape adhesion is determined according to the tape adhesion test of GMW14829 (4th edition, June 2017) (Method A described therein). 【0194】 3. Appearance Appearance is determined by measuring the LW (long wavelength) value and SW (short wavelength) value of the coating using a BYK Wave Scan Meter 2. To meet the criteria of "Class A appearance", the coating should preferably have an LW value of ≤ 10 and an SW value of ≤ 20. 【0195】 4. Resistance to Pressurized Water Spray To evaluate the resistance of the coating to pressurized water spray (steam injection), the method according to VW PV1503B is used. 【0196】 5. Scratch Resistance Dry scratch resistance is measured using an Atlas M38BB electric clock meter (10 cycles with 9-micron paper). 9-micron 3M281Q WETODRY 商標 A 2-inch × 2-inch abrasive paper of 3M is fixed to the cylindrical acrylic finger of the movable arm of the clock meter with a wire clamp. A 4-inch × 12-inch steel test panel coated with the coating is fixed with a magnet under the movable arm. After confirming that the abrasive is smooth against the panel surface, 10 reciprocations (or double rubs) are performed. After sliding the panel to an untested area, the same procedure is repeated 2 times on the same panel using a new 3M paper. After the test, the 20° gloss is measured for both the tested and untested areas of the panel using a BYK Micro TRI gloss meter. The gloss retention rate (%GR) is calculated by taking the average of the gloss of the two tested areas and dividing by the gloss of the untested area. 【0197】 6. Thermal Shock Thermal shock is determined in accordance with the test of GMW15919 (3rd Edition, March 2019). 【0198】 7. Packaging Stability Packaging stability is determined using an imprint test for impact resistance in accordance with DIN EN ISO3678:1995-04. A 500 g round test weight made of metal (diameter 5 cm / height 3 cm). Each sample piece (test piece size: approximately 6×6 cm) is from the packaging materials (tissue paper / packaging bag / packaging towel) that ASP customers usually use for packaging plastic parts that are packaged and coated. Once the oven used is dry, immediately place the test panel in a standard air-conditioned room (23°C / 50% RH (relative air humidity)) and identify each test point. After a waiting time of 10 - 15 minutes, place the first sample of the packaging medium at the first test point and immediately place the test weight on it. After aging periods of 1 hour, 2 hours, 4 hours, and 24 hours after removing from the furnace, place additional samples of each packaging medium at the marked points on the test plate and load additional test weights. The test weights and samples of the packaging medium are removed 24 hours after the start of each individual load test. 【0199】 Evaluation Criteria: 【Table 1】 【0200】 8. Glass Transition Temperature The glass transition temperature is measured by DSC measurement in accordance with DIN EN ISO11357-2 (2019-03). 【0201】 9. Dynamic Light Scattering (DLS) The average particle size of any constituent a5) (and the silica starting material used) is measured by the dynamic light scattering (DLS) method in accordance with the ISO 21501-4 standard. The measurement was carried out using a Beckman coulter device (model: Delsa Nano C particle analyzer, software: Delsa Nano 2.31). The sample solution was prepared at approximately 0.01% with distilled water filtered before checking. 【Example】 【0202】 The following examples further illustrate the present invention but should not be construed as limiting its scope. "Pbw" means parts by weight. Unless otherwise defined, "parts" means "parts by weight". 【0203】 1. Preparation of a 2K primer coating system and the coating material composition obtained therefrom 1.1 The "A" component of the 2K primer coating systems IPC1 and IPC2 used according to the present invention and the 2K primer coating system CPC1 used in the comparative example were prepared by mixing the constituents shown in Table 1.1 in this order. 【0204】 【Table 2】 【0205】 Pigment paste P1 contained 60% by mass of titanium dioxide pigment and further contained an alkyl resin. Pigment paste P2 contained 6% by mass of carbon black pigment and further contained an alkyl resin. Pigment paste P3 contained 10% by mass of an organic blue pigment and further contained an alkyl resin. Pigment paste P4 contained 47% by mass of an inorganic yellow pigment and further contained an alkyl resin. Nacure® 4167 was a commercially available amine-neutralized phosphate catalyst. TIB KAT® 216 was a liquid tin catalyst based on a dioctyltin compound. BYK3565 was a commercially available surface-active additive. Both AS1 and AS2 were commercially available aromatic solvent mixtures and were different from each other. NMP was N-methylpyrrolidone. CPO was a commercially available solution of chlorinated polyolefin (solid content 19.8% by mass). ACL was Acrydic® CL-408, a commercially available solvent-based acrylic resin, was OH-functional, and was modified with chlorinated polypropylene (solid content 44.0 - 46% by mass). The epoxy resin was a reaction product of bisphenol A and DGEBA, which was bisphenol A diglycidyl ether, and had an epoxy equivalent of 465 - 500. 【0206】 The silica-silane condensate used was an MTMS-silica condensate, which was prepared by reacting methyltrimethoxysilane (MTMS) with a commercially available nano-silica dispersion (LUDOX® AS-40) before incorporation into the "A" component of IPC2. To prepare the silica-silane condensate, MTMS (0.45 mol) was mixed with acetic acid (1.45% by mass), and the mixture was cooled to 0 °C. Next, water (9.7% by mass, 0.54 mol) was added, and further LUDOX® AS-40 (24.5% by mass, 0.97 mol, of which 0.16 mol corresponds to silica and the remaining part corresponds to the water also present in this product) was added. Thus, the molar ratio of MTMS to silica was 0.45:0.16, i.e., approximately 2.8. The resulting mixture was then stirred at room temperature for 12 - 16 hours. Thereafter, acetic acid and TBAA (tetrabutylammonium acetate) were added as catalysts (acetic acid 3.13% by mass and TBAA 0.17% by mass), and the mixture was stirred for 2 - 3 hours while maintaining the pH at 5.1. The resulting mixture (solid content 43% by mass) was diluted with isopropyl alcohol (mass ratio 1:1) and then used in this form as the silica-silane condensate for preparing the "A" component of IPC2. 【0207】 1.2 The "B" component used in the 2K primer coating systems IPC1, IPC2, and CPC1 was prepared by mixing the components shown in Table 1.2 in this order. 【0208】 【Table 3】 【0209】 Desmodur® N3600 was a commercially available aliphatic polyisocyanate (HDI trimer). Dynasylan® 1189 was N-(3-(trimethoxysilyl)propyl)butylamine. Dynasylan® 1124 was bis(trimethoxysilylpropyl)amine. 【0210】 1.3 The primer coating material composition is prepared by mixing the "A" component and the "B" component of the primer coating system IPC1 in a mass ratio of 12.89:1 ( "A" to "B"), or in the case of the primer coating system CPC1 in a mass ratio of 12.89:1 ( "A" to "B"), or in the case of the primer coating system IPC2 in a mass ratio of 14.44:1 ( "A" to "B"). 【0211】 The calculation and selection of the mixing ratio were carried out such that the polyisocyanate derived from component "B" still exists in an excess of about 10 - 12% by mass in the resulting composition, and when the base coat film applied thereafter is applied onto the primer coating film obtained by applying the primer coating material composition onto the surface of the substrate, it is cured through the migration of NCO. 【0212】 2. Preparation of the 2K clear coat system and the clear coat material composition obtained therefrom 2.1 The "A" component of the 2K clear coat system ICC1 was prepared by mixing the constituent components shown in Table 2.1 in this order. 【0213】 【Table 4】 【0214】 The catalyst 1 was a commercially available catalyst, namely TIB KAT (registered trademark) 216 (DOTL), a liquid tin catalyst based on dioctyltin compounds. The additive 1 was a commercially available liquid hydroxyphenyltriazine (HPT) UV absorber. The additive 2 was a commercially available liquid hindered amine light stabilizer. The additive 3 was a commercially available silicone-containing surface additive. The additive 4 was a commercially available antifoaming agent. Nacure (registered trademark) 4167 has already been described in this specification. AS3 was a commercially available aromatic solvent mixture, different from AS1 and AS2 specified above in this specification. The acrylic resin 1 was a solution of an OH-functional (meth)acrylic resin having a T of -15 °C prepared from N-butyl methacrylate, styrene, 4-hydroxybutyl acrylate, and 2-hydroxyethyl acrylate (solid content: 65% by mass). g The acrylic resin 2 was a dispersion of an OH-functional (meth)acrylic resin having a T of +34 °C prepared from 3-hydroxypropyl methacrylate, 2-ethylhexyl (meth)acrylate, and cyclohexyl (meth)acrylate (solid content: 67.5% by mass). g The acrylic resin 3 was a dispersion of an OH-functional (meth)acrylic resin having a T of +46 °C prepared from n-butyl methacrylate, styrene, cyclohexyl methacrylate, 2-hydroxypropyl methacrylate, and 2-hydroxyethyl methacrylate (solid content: 60.0% by mass). g It was a dispersion of an OH-functional (meth)acrylic resin having a T of +46 °C prepared from n-butyl methacrylate, styrene, cyclohexyl methacrylate, 2-hydroxypropyl methacrylate, and 2-hydroxyethyl methacrylate (solid content: 60.0% by mass). 【0215】 2.2 The "B" component of the 2K clear coat-based ICC1 was a polyisocyanate. A part of the NCO groups of the polyisocyanate (product Desmodur® N3600 was used as the starting material) was silanized using two different organosilanes, namely Dynasylan® 1189 and Dynasylan® 1124, before being used as the "B" component / in the "B" component. Desmodur® N3600 was a commercially available aliphatic polyisocyanate (HDI trimer). Dynasylan® 1189 was N-(3-(trimethoxysilyl)propyl)butylamine. Dynasylan® 1124 was bis(trimethoxysilylpropyl)amine. The "B" component was commercially available (the "B" component of iGloss® refinish). 【0216】 2.3 The clear coat material composition was prepared by mixing the "A" component of the clear coat-based ICC1 and the "B" component at a mass ratio of 1:1 ( "A" to "B") with each other. 【0217】 3. Preparation of the multilayer coating system 3.1 As outlined below in this specification, many multilayer coating systems were obtained by utilizing the aforementioned primer and clear coat material compositions and by utilizing one of the different base coat (intermediate coat) material compositions in each case. 【0218】 3.2 Multilayer coating systems comprising a primer layer obtained from IPC1 or IPC2, a base coat layer, and a clear coat layer obtained from ICC1 (all invention examples) The product Ultramid® XA3418, a carbon fiber (C fiber) reinforced plastic substrate, i.e., carbon fiber reinforced polyamide, was used as the substrate. The primer coating material composition obtained from primer coating system IPC1 or IPC2 prepared as described in item 1.3 was applied to the surface of the substrate to form a primer film, and then flashed for 10 minutes under ambient conditions (room temperature). Next, one of the base coat material compositions SBBC1 - SBBC4 (each being solvent-based) or WBBC1 - WBBC4 (each being water-based) was sprayed onto the primer film to form a base coat film, and then flashed for 10 minutes under ambient conditions (room temperature). In the case of the water-based base coat material composition (WBBC), further flash-off was carried out at a high temperature of 140°F (60°C) for 5 minutes. Then, the clear coat material composition obtained from clear coat system ICC1 prepared as described in item 2.3 was applied onto the base coat film, and after flashing for 10 minutes under ambient conditions (room temperature), all the films were simultaneously baked at a substrate temperature of 122°F (50°C) for 30 minutes. 【0219】 The dry film thickness of each primer layer obtained from each primer film after curing was in the range of 0.5 - 1 mil (12.7μm - 25.4μm). The dry film thickness of each base coat layer obtained from each base coat film after curing was in the range of 0.6 - 1 mil (15.24μm - 25.4μm), and the dry film thickness of each clear coat layer obtained from each clear coat film after curing was in the range of 1.9 - 2.1 mil (48.26μm - 53.34μm). 【0220】 SBBC1 - SBBC4 were base coat material compositions with different high-solids solvent-based pigments. The following commercially available products were used: SBBC1: Shadow Black SBBC2: Ingot Silver SBBC3: Oxford White SBBC4: Hot Pepper Red. 【0221】 The spray viscosities of SBBC2 to SBBC4 were adjusted to approximately 35 cP before application using a suitable solvent, such as n-butyl acetate. The spray viscosity of SBBC1 was adjusted to approximately 55 cP before application using a suitable solvent, such as n-butyl acetate. 【0222】 WBBC1 to WBBC4 were aqueous-based base coat material compositions with different high-solid pigments. The following commercial products were used: WBBC1: Exterior Black WBBC2: Switch Blade Silver WBBC3: Avalon White WBBC4: Coated Red Handed. 【0223】 The spray viscosities of WBBC1 to SBBC4 were adjusted to approximately 90 - 95 cP before application. 【0224】 3.3 A further multi-layer coating system comprising a primer layer obtained from IPC1, a base coat layer, and a clear coat layer obtained from ICC1 (all invention examples) A further multi-layer coating system was prepared using the same type of coating material composition in the same manner as described in item 3.2. The only difference was that in addition to Ultramid® XA3418, three further different substrates were used, namely the following substrates S1 to S4: S1: Steel (CG800) S2: Ultramid® XA3418 (the same as in the series of item 3.2) S3: Carbon fiber reinforced polypropylene (20% by mass) (CB201SY) S4: TPO (thermoplastic olefin) That is what was used. 【0225】 3.4 Comparative experiments 3.4.1 A further multi-layer coating system was prepared using SBBC1 as the base coat in the same manner as described in item 3.2 and including a clear coat layer obtained from ICC1. However, instead of IPC1, a commercially available internally cross-linked 1K primer coating material composition, namely Med Gray AdPro which contains no polyisocyanate nor ACL (Acrydic® CL-408, a commercially available solvent-based acrylic resin modified with chlorinated polypropylene and having an OH-functional modified resin), was used. Instead, the commercially available 1K primer coating material composition used contained an epoxy resin and an alkyd resin. This multi-layer coating system is referred to as Comparative Example CE1. 【0226】 3.4.2 A further multi-layer coating system was prepared using SBBC1 as the base coat in the same manner as described in item 3.2 and including a clear coat layer obtained from ICC1. However, instead of IPC1, the 2K primer coating system CPC1 of the comparative example was used. This multi-layer coating system is referred to as Comparative Example CE2. 【0227】 3.4.3 A further multi-layer coating system was prepared using SBBC1 as the base coat in the same manner as described in item 3.2 and including a clear coat layer obtained from ICC1. However, instead of IPC1, the commercially available 2K clear coat product Evergloss® 905 was used as the primer coating material composition. This multi-layer coating system is referred to as Comparative Example CE3. 【0228】 3.4.4 A further multi-layer coating system was prepared using SBBC1 as the base coat in the same manner as described in item 3.2 and including a clear coat layer obtained from ICC1. However, instead of IPC1, a commercially available 2K clear coat system (Refinish iGloss®) was used as the primer coating material composition. This multi-layer coating system is referred to as Comparative Example CE4. 【0229】 3.4.5 A further multi-layer coating system was prepared using SBBC1 as the base coat in the same manner as described in item 3.2. However, for the preparation of the clear coat layer, instead of ICC1, a commercially available 2K clear coat product Evergloss® 905 was used. Further, for the preparation of the primer layer, instead of IPC1, a commercially available 1K primer Med Gray AdPro was used. Further, a firing temperature of 80 °C (not 50 °C) was used. This multi-layer coating system is referred to as comparative example CE5. 【0230】 3.4.6 A further multi-layer coating system was prepared using SBBC1 as the base coat in the same manner as described in item 3.2. IPC1 was used for the preparation of the primer layer. However, ICC1 was not used for the preparation of the clear coat layer. Instead, three different clear coat systems were used, each containing the "A" component of the clear coat system ICC1 but different "B" components. In each case, the different "B" components contained no silanized polyisocyanate and only non-silanized polyisocyanate. For the preparation of the multi-layer coating system according to comparative example CE6, only Desmodur® N3600 was used as the "B" component of the clear coat system used. For the preparation of the multi-layer coating system according to comparative example CE7, the "B" component of the commercially available clear coat system Evergloss® 905 was used. For the preparation of the multi-layer coating system according to comparative example CE8, the "B" component of the commercially available clear coat system 2K4® was used. 【0231】 4. Properties of substrates coated with the multi-layer coating system 4.1 Tables 4.1a, 4.1b and 4.1c summarize many of the properties measured and / or determined according to the methods defined in the "Method" section. These are obtained for the multi-layer coating system present on the carbon fiber reinforced plastic substrate prepared as described in item 3.2. 【0232】 [Table 5] 【0233】 【Table 6】 【0234】 【Table 7】 【0235】 4.2 Further, an accelerated weathering test was conducted in accordance with SAE J2527 and ASTM 7869 methods using a multilayer coating system present on different substrates described in item 3.3. All multilayer coating systems on all substrates passed the test. 【0236】 4.3 Table 4.2 summarizes many properties measured and / or determined according to the methods defined in the "Method" section. These are for the comparative example multilayer coating system CE1 prepared as described in item 3.4.1 herein, for the comparative example multilayer coating system CE2 prepared as described in item 3.4.2 herein, for the comparative example multilayer coating system CE3 prepared as described in item 3.4.3 herein, and for the comparative example multilayer coating system CE4 prepared as described in item 3.4.4 herein. 【0237】 【Table 8】 【0238】 Each of CE1 to CE4 had poor tape adhesion, steam injection, and thermal shock properties after humidity exposure. The "black band" that appears when using the tape adhesion test indicates insufficient base coat curing. In this regard, it was found that using excessive isocyanate in the clear coat does not improve base coat curing. Further, the SW values of each of CE2 to CE4 were too high to meet the requirements of Class A for appearance. 【0239】 4.4 Summarize in Table 4.3 many of the properties measured and / or determined according to the methods defined in the "Method" section. These are those obtained for the multilayer coating system CE5 of the comparative example prepared as described in item 3.4.5 herein. 【0240】 【Table 9】 【0241】 CE5 had both LW and SW values that were too high to meet the requirements of Class A for appearance. 【0242】 4.5 Summarize in Table 4.5 the data on packaging stability measured according to the methods defined in the "Method" section and evaluated according to the conditions identified therein. These are those obtained for the multilayer coating system of the present invention having a primer layer obtained from IPC1, a base coat layer obtained from SBBC1, and a clear coat layer obtained from ICC1. 【0243】 【Table 10】 【0244】 4.6 Summarize in Table 4.6 many of the properties measured and / or determined according to the methods defined in the "Method" section. These are those obtained for the multilayer coating systems CE6, CE7, and CE8 of the comparative example prepared as described in item 3.4.6 herein. 【0245】 【Table 11】 【0246】 CE6 - CE8 had poor appearance and inferior tape adhesion after humidity exposure (CE7 and CE8), steam injection, and thermal shock properties (each of CE6 - CE8).

Claims

[Claim 1] A substrate that is optionally pre-coated and consists of at least three different coating layers L1, L2, and L3, i.e. A multilayer coating system comprising a first coating layer L1, a second coating layer L2, and a third coating layer L3, The first coating layer L1 is applied to at least a portion of an optionally pre-coated substrate, and the layer L1 is obtained from a primer coating composition. The primer coating composition is obtained from a primer coating system comprising at least two components A) and B) and optionally at least one further component C), which are different from and separate from each other. Component A) is composed of at least one component a2) and optionally at least one component a1), that is, Optionally, at least one organic solvent a1), and At least one polymer a2) is a (meth)acrylic polymer that contains a functional group reactive to an NCO group and is modified with at least one chlorinated polyolefin. Includes, Component B) consists of at least two different constituent components b2) and optionally at least one constituent component b1), i.e. Optionally, at least one organic solvent b1), and (b2) At least one organic component having two or more NCO groups on average It includes, and Any component C) is a reducing agent component, and the mixture contains at least one organic solvent c1), The second coating layer L2 is applied on the first coating layer L1, and the layer L2 is obtained from the base coat composition. The third coating layer L3 is applied on the second coating layer L2, and the layer L3 is obtained from a clear coat composition. Layer L3 is obtained from a 2K clear coat composition, which is obtained from a clear coat system comprising at least two components D) and E) and optionally at least one further component F), which are different from and separated from each other. Component D) is composed of at least one component d2) and optionally at least one component d1), i.e. Optionally, at least one organic solvent d1), and At least one OH-functionalized (meth)acrylic polymer d2) Includes, Component E) is composed of at least one component e2) and optionally at least one component e1), i.e. Optionally, at least one organic solvent e1), and An organic component e2) having, on average, two or more NCO groups, wherein at least some of these NCO groups have reacted with at least one organosilane before incorporating component e2) into component E). It includes, and Any component F) is a reducing agent component, and the mixture contains at least one organic solvent f1), Multi-layer coating system. [Claim 2] The multilayer coating system according to claim 1, wherein the at least three coating layers L1, L2, and L3 are arranged adjacent to each other, and / or the third coating layer L3 is the outermost coating layer of the multilayer coating system. [Claim 3] The multilayer coating system according to claim 1 or 2, wherein the substrate is selected from a metal substrate and a plastic substrate, preferably a plastic substrate, more preferably a fiber-reinforced plastic substrate, and even more preferably a carbon fiber-reinforced plastic substrate. [Claim 4] The multilayer coating system according to claim 1 or 2, which, when measured by the method disclosed in the specification, exhibits an LW (long wavelength) value ≤ 10 and an SW (short wavelength) value ≤ 20. [Claim 5] The multilayer coating system according to claim 1 or 2, wherein polymer a2) is contained in component A) of the primer coating system in an amount ranging from 5.0 to 50.0% by mass, preferably 10.0 to 45.0% by mass, more preferably 15.0 to 40.0% by mass, and more preferably 17.5 to 35.0% by mass, and these mass percentages are relative to the total mass of component A). [Claim 6] The component A) of the primer coating system further comprises at least one of components a3) and a4), preferably both components a3) and a4), which are different from each other and different from each of components a1) and a2), Component a3) is a catalyst a3) suitable for crosslinking NCO groups, particularly the NCO groups of component b2) of component B), and component a3) is preferably selected from organotin catalysts and / or preferably present in component A) of the primer coating system in an amount ranging from 0.001 to 1.00% by mass, preferably 0.002 to 0.80% by mass, more preferably 0.003 to 0.60% by mass, even more preferably 0.004 to 0.40% by mass, even more preferably 0.005 to 0.20% by mass, and most preferably 0.007 to 0.15% by mass, where these mass percent are relative to the total mass of component A), and The multilayer coating system according to claim 1 or 2, wherein component a4) is a catalyst a4), preferably selected from phosphorus-containing organic components that are not blocked by any amine, and at least one catalyst a4) is preferably present in component A) of the primer coating system in an amount ranging from 0.01 to 2.50% by mass, more preferably 0.02 to 2.0% by mass, even more preferably 0.03 to 1.5% by mass, even more preferably 0.04 to 1.2% by mass, and still more preferably 0.05 to 1.0% by mass, and these mass percent are relative to the total mass of component A). [Claim 7] The component A of the primer coating system further comprises at least one component a5) which is different from any of the components a1) to a4) and is a condensation product, and the condensation product is obtained by the reaction of (i) at least one organosilane having at least one hydrolyzable group and (ii) at least one type of silica, and the molar ratio of the at least one organosilane to the at least one type of silica used in the preparation of the condensation product a5) is preferably 10:1 to 1:1, preferably 8:1 to 1:1, more preferably 6:1 to 1:1, and even more preferably 4:1 to 1:

1. The multilayer coating system according to claim 6, more preferably in the range of 4:1 to 1.1:1, even more preferably in the range of 4:1 to 1.5:1, and most preferably in the range of 4:1 to 2:1, and / or the at least one condensation product a5) is present in component A) in an amount of 1.0 to 25.0% by mass, preferably 2.0 to 20.0% by mass, more preferably 3.0 to 17.5% by mass, even more preferably 4.0 to 15.0% by mass, also more preferably 5.0 to 14.0% by mass, even more preferably 6.0 to 13.0% by mass, and most preferably 7.0 to 12.0% by mass, where these mass percent are relative to the total mass of component A). [Claim 8] The multilayer coating system according to claim 6, wherein component A) of the primer coating system further comprises at least one leveling agent and / or dispersant as additive component a9), the component being different from any of components a1) to a4), preferably being a (meth)acrylate polymer, preferably containing at least one ether segment, more preferably in its side chain, and / or preferably containing at least one siloxane unit, more preferably in its side chain, and component a9) is preferably present in component A) in an amount of 0.10 to 5.0% by mass, more preferably 0.50 to 4.0% by mass, and more preferably 0.80 to 3.5% by mass, with these mass percentages being relative to the total mass of component A). [Claim 9] The clear coat system component D) comprises at least two OH-functional (meth)acrylic polymers d2) and d3), wherein the polymers are different from each other, the amount of component d2) in component D) preferably exceeds the amount of component d3), and the at least one OH-functional (meth)acrylic polymer d3) has a glass transition temperature (T) of the at least one OH-functional (meth)acrylic polymer d2). ｇ Glass transition temperature (T) lower than ) ｇ ) has, preferably the at least one OH-functionalized (meth)acrylic polymer d2) has a glass transition temperature (T) in the range of +10°C to +75°C, preferably +15°C to +70°C, more preferably +20°C to +65°C, even more preferably +25°C to +60°C, even more preferably +30°C to +55°C, most preferably +35°C or +40°C to +50°C. ｇ ) and preferably the at least one OH-functionalized (meth)acrylic polymer d3) has a glass transition temperature (T) in the range of -70°C to <+10°C, preferably -60°C to +5°C, more preferably -50°C to 0°C, even more preferably -45°C to 0°C, even more preferably -40°C to 0°C, even more preferably -35°C or -30°C to -5°C, most preferably -25°C or -5°C. ｇ A multilayer coating system according to claim 1 or 2, having the following characteristics: [Claim 10] The clear coat system component D) further comprises at least one of the constituent components d4) and d5), which are different from each of the constituent components d1) to d3), preferably both constituent components d4) and d5), The component d4) is at least one catalyst d4) suitable for crosslinking NCO groups, particularly the NCO groups of component e2) of component E), preferably selected from organotin catalysts, and is identical to or different from catalyst a3), and catalyst d4) is preferably present in component D) of the clear coat system in an amount ranging from 0.001 to 3.00% by mass, preferably 0.01 to 2.50% by mass, more preferably 0.05 to 2.00% by mass, even more preferably 0.10 to 1.50% by mass, even more preferably 0.20 to 1.25% by mass, and most preferably 0.30 to 1.00% by mass, where these mass percent are relative to the total mass of component D), The multilayer coating system according to claim 9, wherein component d5) is at least one catalyst d5), preferably selected from phosphorus-containing organic components not blocked by any amine, and is identical to or different from catalyst a4), preferably in an amount in the range of 0.01 to 6.00% by mass, preferably 0.10 to 5.50% by mass, more preferably 0.40 to 5.00% by mass, even more preferably 0.70 to 4.50% by mass, still more preferably 1.00 to 4.00% by mass, and most preferably 1.10 to 3.75% by mass, and these mass percent are relative to the total mass of component D). [Claim 11] At least one component e2) of component E) of the clear coat system is of formula (I) -NR-(X-SiR’’ ｘ (OR’) ３－ｘ ) (I)、 at least one structural unit, and / or preferably and formula (II) -N(X-SiR’’ ｘ (OR’) ３－ｘ ) ｎ (X’-SiR’’ ｙ (OR’) ３－ｙ ) ｍ (II)、 at least one structural unit It has, During the ceremony, R is hydrogen, alkyl, cycloalkyl, aryl, or aralkyl, and the carbon chain is an adjacent oxygen group, sulfur group, or NR ａ It may be interrupted by the base, and this R ａ These are alkyl, cycloalkyl, aryl, or aralkyl, Each R' is independently a hydrogen, alkyl, or cycloalkyl group, and the carbon chain is not adjacent to an oxygen group, sulfur group, or NR. ａ The group may be interrupted, preferably each R' is ethyl and / or methyl. Each X and X' is a linear and / or branched alkylene or cycloalkylene group having 1 to 20 carbon atoms independently of each other, preferably each X and X' is an alkylene group having 1 to 4 carbon atoms. Each R'' is independently alkyl, cycloalkyl, aryl, or aralkyl, and the carbon chain is not adjacent to an oxygen group, sulfur group, or NR ａ The group may be interrupted by a group, preferably each R'' is an alkyl group, more preferably having 1 to 6 C atoms. n is a parameter between 0 and 2, m is a parameter between 0 and 2, m + n is 2, and x and y are parameters between 0 and 2. and / or 10 to 80 mol%, preferably 15 to 70 mol%, more preferably 20 to 50 mol%, and even more preferably 25 to 40 mol%, of the isocyanate groups originally present in at least one component (b2) react with the at least one organosilane, preferably forming structural units (I) and / or (II), more preferably forming structural units (I) and (II), and / or further comprises at least one organic component e3) having an average of two or more NCO groups, which is different from component e2) and does not contain any silane-modified NCO groups, and is identical to or different from component b2), wherein the at least one organic component e3) present in component E) preferably has an aliphatic or alicyclic parent structure, and / or a parent structure derived from an aliphatic or alicyclic polyisocyanate by trimerization, dimerization, urethane formation, biuret formation, uretdione formation and / or allophanate formation. The multilayer coating system according to claim 1 or 2. [Claim 12] A method for applying a multilayer coating system as defined in claim 1 or 2, comprising at least three distinct coating layers L1, L2, and L3, onto a substrate selected from a metal substrate and a plastic substrate, preferably from a plastic substrate, more preferably from a fiber-reinforced plastic substrate, and even more preferably from a carbon fiber-reinforced plastic substrate. [Claim 13] A method for preparing a multilayer coating system on at least one surface of an optionally pre-coated substrate, comprising at least steps 1) to 3) and optionally step 4), i.e., 1) Apply the first coating composition to at least partially one surface of an optionally pre-coated substrate to form a first coating film on the surface. The first coating composition is the primer coating composition defined in claim 1, in the step, 2) A step of applying at least one base coat composition as at least one second coating composition to the first coating film present on the substrate obtained after step 1), preferably before curing the first coating film, to form a second coating film preferably adjacent to the first coating film, and 3) A clear coat composition is applied as a third coating composition to the second coating film present on the substrate obtained after step 2), preferably before curing the second coating film, thereby forming a third coating film which is preferably adjacent to the second coating film and is the outermost layer of the formed multilayer coating. The third coating composition is the clear coat composition defined in claim 1, in the step, 4) A step of optionally curing the first, second, and third coating films together to obtain a multilayer coating system including the cured first, second, and third coating layers, wherein, in particular, when a plastic substrate or a fiber-reinforced plastic substrate is optionally used as the substrate to be pre-coated, the curing is preferably performed at a temperature not exceeding 80°C, more preferably not exceeding 70°C, more preferably not exceeding 60°C, and even more preferably not exceeding 55°C. Methods that include... [Claim 14] The method according to claim 13, wherein the resulting multilayer coating system is the multilayer coating system described in claim 1. [Claim 15] At least the following, separated from each other, namely A primer coating system comprising at least two components A) and B) as defined in claim 1 and optionally at least one further component C), and A kit of parts comprising a 2K-clear coat system suitable for preparing a clear coat composition comprising at least two components D) and E) as defined in claim 1 and optionally at least one further component F).