A primer coating system and composition that achieve excellent water resistance

Abstract

The present invention relates to a primer coating system comprising at least two components A) and B) which are different from each other and separate, wherein component A) in particular comprises at least one condensation product a3) in addition to at least constituent a2), and this condensation product can be obtained by the reaction of at least (i) at least one organosilane having at least one hydrolyzable group and (ii) at least one kind of silica, component B) comprises at least one organic component b2) having on average two or more NCO groups, a primer coating composition obtained by mixing at least components A) and B) with each other, or a 1K primer coating composition comprising at least the condensation product a3) in addition to a film-forming polymer, a method for using the primer coating composition according to the claims for improving the water resistance and / or moisture resistance of a cured coating film and a multilayer coating obtained therefrom, a method for coating a substrate by applying at least the primer coating composition, a coated substrate obtainable therefrom, a method for preparing a multilayer coating system comprising at least one primer coating film obtainable from the primer coating composition, and such a multilayer coating system.

Description

Technical Field

[0001] The present invention relates to a primer coating system comprising at least two components A) and B), a primer coating composition obtainable by mixing these components of the primer coating system with each other, or a 1K primer coating composition per se, a cured primer coating film obtainable therefrom, and / or a method of using a primer coating composition for improving the water resistance and / or moisture resistance of a cured multilayer coating system containing such a cured film, a method of coating a substrate using the primer coating composition, a method of preparing a multilayer coating system using the primer coating composition to provide a primer coating film within the system, and a multilayer coating system present on a substrate comprising at least three layers, one of which is obtained from the primer coating film.

Background Art

[0002] In a typical automotive painting process, usually in the form of a multilayer coating system, a plurality of layers are applied to the surface of a suitable substrate. In particular, when using a plastic or fiber-reinforced plastic substrate, at least a primer, at least one base coat, and a top coat, in particular a clear coat as the outermost layer, are applied in this order. Currently, typically, at least the base coat and the top coat are applied in a wet-on-wet manner. Thereafter, the coated substrate is passed through an oven at a temperature for simultaneously curing at least the base coat(s) and the top coat, such as a clear coat, for example, in a 2C1B process. In some cases, for example, in a 3C1B process, the primer coat is also cured at this stage together with the base coat and the top coat, in particular the clear coat.

[0003] Single-layer films and multi-layer films existing in multi-layer coatings used in the automotive industry need to meet a very large number of requirements not only for regulatory purposes but also for quality standards set by the automotive industry. Therefore, multi-layer coatings need to exhibit at least a sufficient number of desired properties in order to meet these requirements.

[0004] For example, it is desirable to avoid failure of the film or layer due to exposure to harsh external weather conditions, mainly caused by the penetration of moisture from the coated film of the multi-layer coating into the substrate. Therefore, in order to avoid swelling of the substrate used, especially a polar substrate, and to maintain a durable appearance, especially in combination with good adhesion properties between the primer and the substrate, it is desirable to achieve excellent water vapor barrier properties. For automotive exterior parts, providing such a durable coating layer with good adhesion properties is one of the important requirements for maintaining the life of the painted automotive exterior parts. In the case of plastic substrates including reinforced plastic substrates, a durable coating layer is essential so that they can be used as alternatives to metal parts. Especially in the case of polar substrates, it is difficult to maintain a durable coating layer on the substrate because they tend to absorb moisture in the air under ambient conditions.

[0005] In many cases, conventional automotive coating systems exhibit only insufficient water vapor barrier properties, and as a result, defects, especially appearance defects, occur in the painted parts after a certain period of time.

[0006] Therefore, there is a need to provide new coating films and multi-layer coating systems that are less permeable or at least less permeable than those observed in conventional coating films and multi-layer coating systems on substrates, especially plastic substrates including reinforced plastic substrates, that is, exhibit excellent water vapor barrier properties (water resistance), and as a result, can maintain a durable coating film and multi-layer coating system with excellent appearance even after a long period of time. Summary of the Invention

Problems to be Solved by the Invention

[0007] Problems Accordingly, the underlying object of the present invention is to provide a coating film and a multilayer coating system that are less or at least less hygroscopic than those observed with conventional coating films and multilayer coating systems on a substrate, particularly a plastic substrate including a reinforced plastic substrate, and thus exhibit excellent water vapor barrier properties. In particular, as a result of these improved barrier properties, it is possible to maintain a durable coating film and a multilayer coating system having excellent appearance even after a long period of time.

Means for Solving the Problems

[0008] This object is solved by the subject matter of the claims of the present application and its preferred embodiments disclosed herein, i.e., by the subject matter described herein.

[0009] A first subject of the present invention is a primer coating system comprising at least two components A) and B) that are different from each other and separate from each other, and optionally at least one further component C), wherein component A) comprises at least constituents a2) and a3) that are different from each other, and optionally at least one constituent a1), i.e., optionally at least one organic solvent a1), at least one polymer a2) containing a functional group reactive with an NCO group, preferably at least one OH-functional polymer, and at least one condensation product a3) obtainable at least by the reaction of (i) at least one organosilane having at least one hydrolyzable group and (ii) at least one silica, wherein the molar ratio of at least one organosilane to at least one silica used is preferably in the range of 10:1 to 1:1, at least one condensation product a3) comprising, Component B) comprises at least two different constituents b2) and optionally at least one constituent b1), namely optionally at least one organic solvent b1), and at least one organic component b2) having on average two or more NCO groups and any optional Component C) is a reducing agent component and contains at least one organic solvent c1).

[0010] A further subject of the present invention is a primer coating composition, which can be obtained by mixing at least Components A) and B) and optionally C) of the primer coating system of the present invention with each other, or Components (i), (ii) and (iii), and optionally (iv), which are different from each other, namely (i) at least one organic solvent corresponding preferably to at least one of the organic solvents a), b1) and / or c1) defined for the primer coating system of the present invention, (ii) at least one film-forming polymer which is self-crosslinkable or externally crosslinkable, preferably externally crosslinkable, more preferably corresponding to at least one polymer a2), and contains a functional group which is reactive towards the NCO groups as defined for the primer coating system of the present invention, (iii) at least one condensation product corresponding to the condensation product a3) defined for the primer coating system of the present invention, and (iv) optionally, when at least one film-forming polymer (ii) is an externally crosslinkable polymer, preferably at least one crosslinking agent selected from blocked polyisocyanates, melamine formaldehyde resins and mixtures thereof and

[0011] ​A further subject of the present invention is a method of using the primer coating composition for improving the water resistance and / or moisture resistance of a cured primer coating film obtainable therefrom and / or a cured multilayer coating system containing at least one cured primer coating film, wherein the cured primer coating film is obtainable from the primer coating composition.

[0012] A further subject of the present invention is at least step 1) and optionally step 1a), namely 1) applying the primer coating composition at least partially to at least one surface of an optionally pre-coated substrate to form a primer coating film on the surface, and 1a) optionally, at least one further step 1a) of curing at least one primer coating film obtained after step 1) to obtain at least one cured primer coating layer on the surface which is a method of coating a substrate.

[0013] A further subject of the present invention is a coated substrate obtainable by the method.

[0014] A further subject of the present invention is at least steps 1) to 3) and optionally 4), namely 1) a step of applying a first coating composition at least partially to at least one surface of an optionally pre-coated substrate to form a first coating film on the surface, wherein the first coating composition is the primer coating composition, and 2) 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 preferably form a second coating film adjacent to the first coating film, and 3) On the second coating film present on the substrate obtained after step 2), preferably before curing the second coating film, apply a topcoat composition, preferably a clearcoat composition, as the third coating composition, preferably adjacent to the second coating film, and preferably form a third coating film which is the outermost coating film of the formed multilayer coating system. 4) Optionally, co-cure the first, second, and third coating films to obtain a multilayer coating system comprising cured first, second, and third coating layers. A method for preparing a multilayer coating on at least one surface of an optionally pre-coated substrate, comprising the steps of:

[0015] A further subject of the present invention is a multilayer coating system present on an optionally pre-coated substrate, which can preferably be obtained by the above method for preparing a multilayer coating system, wherein the multilayer coating system comprises at least three coating layers L1, L2, and L3 which are different from each other and are preferably arranged adjacent to each other, i.e., A first coating layer L1 applied on at least a part of the optionally pre-coated substrate, wherein the layer L1 can be obtained from the primer coating composition of the present invention. A second coating layer L2 applied on the first coating layer L1, and A third coating layer L3 applied on the second coating layer L2, wherein the third coating layer L3 is preferably the outermost coating layer of the multilayer coating system. Including.

[0016] Particularly surprisingly, it has been found that the water vapor permeability of the self-curing primer film obtained from the primer coating system of the present invention (said film being obtained from the primer coating composition of the present invention) can be significantly reduced by the presence of the condensation product a3) in component A) of the primer coating system. As shown in Figure 1, a significant difference in water vapor permeability is observed: the film obtained from the primer coating composition of the present invention containing constituent a3) has a permeability that is approximately 35% lower than that of the control film obtained from the primer coating composition not containing constituent a3). Thus, in the absence of constituent a3), a poorer moisture barrier property is observed.

[0017] Furthermore, particularly surprisingly, a plastic substrate, in particular a carbon fiber reinforced plastic substrate such as a carbon fiber reinforced polyamide-containing substrate, coated with a multilayer coating system comprising a primer layer derived from a primer film obtained from a primer coating composition obtained from the primer coating system of the present invention containing constituent a3) in component A), contains a control primer film instead of the primer coating film of the present invention, and the control primer film has been found to have significantly less (less than about 40% by mass) water (moisture) uptake after humidity exposure and storage compared to a substrate coated with the same multilayer coating system but not containing constituent a3). Furthermore, surprisingly, this effect has been observed for a plurality of different types of substrates and has also been found to be independent of the nature of the base coat materials (solvent-based base coats and water-based base coats) used as intermediate coats for preparing the multilayer coating system.

[0018] In particular, surprisingly, in the case of a carbon fiber reinforced polyamide (PA-CF) substrate having a multilayer coating system, when using a conventional primer, the appearance is dynamic. In particular, although it is considered to be due to the highly polar nature of the polyamide substrate, it has been found that the appearance deteriorates over time under ambient conditions because it absorbs moisture from the air and swells. This undesirable effect was not observed when using the primer film of the present invention containing component a3).

[0019] Furthermore, the primer coating composition of the present invention can be cured at a low temperature of 50 °C, which is energy-efficient and environmentally friendly, and has been found to be particularly advantageous when the substrate used is a plastic substrate.

[0020] Furthermore, the primer coating film of the present invention obtained from the primer coating composition of the present invention has the ability to at least partially cure the basecoat film applied on the primer coating film even at a low temperature of 50 °C due to the migration of isocyanate from the primer film to the basecoat film. In particular, when the primer coating composition used contains an excess of component b2) having on average two or more NCO groups, and the film preferably contains at least one polymer component containing a functional group reactive with the NCO groups of component b2), at least partial curing is achieved.

Brief Description of the Drawings

[0021]

Figure 1

Figure 2

Modes for Carrying Out the Invention

[0022] Detailed Description of the Invention The term "comprising" in the context of the present invention preferably has the meaning of "consisting of" in relation to, for example, one of the components of a primer coating composition or a primer coating system. In relation to one of the components of a primer coating composition or a primer coating system, it is also possible, for example, in addition to all the essential components present therein, for one or more of the further optional components specified below to be comprised therein. All components may be present in their preferred embodiments as specified below, in each case.

[0023] The percentages and amounts by wt.-% (mass %) of any of the components shown below present in each coating composition, such as a primer coating composition, are in each case based on the total mass of the coating composition and add up to 100 mass %. The same applies to each component of a coating system, such as component A) or B) of a primer coating system: the percentages and amounts in units of wt.-% (mass %) of the components shown below comprised in any of these components are in each case based on the total mass of each component and add up to 100 mass %.

[0024] Primer coating system As outlined in this specification, the primer coating system comprises at least two components A) and B), and optionally at least one further component C), which are different from each other and separate from each other, i.e., it is a two-component (2K) or multi-component coating system. Being separate from each other in this context means that the components A) and 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 a substrate, preferably, at least a polyurethane or polyurethane-based coating film is formed by the reaction of the OH group of at least one constituent a2) and the isocyanate group of at least one constituent b2).

[0025] Preferably, both components A) and B) of the coating system, and optionally component C), 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 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 water is not intentionally added to any of components A) and B) and optionally C) used in the present invention, nor to the coating composition obtained therefrom. However, it cannot be denied that residues of water formed during the preparation of any of the components used to prepare components A) and B) and optionally C) used in the present invention are present therein. 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, even more preferably less than 0.05% by weight, even more preferably less than 0.01% by weight, particularly less than 0.005% by weight or less than 0.001% by weight, based on the total weight of component A) or B) or optionally C) in each case. Preferably, both components A) and B) of the coating system, and optionally component C), 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.

[0026] Component A Component A) comprises at least constituents a2) and a3), which are different from each other, and optionally a1), but may further comprise additional optional constituents.

[0027] Preferably, component A) of the primer coating system has a total solids content of >20% by mass, preferably >25% by mass, more preferably >30% 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, even more preferably 30 to 45% by mass, in each case based on 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.

[0028] Any constituent a1) Any constituent a1) is at least one organic solvent. Examples of such organic solvents include heterocyclic, aliphatic, or aromatic hydrocarbons, monohydric or polyhydric alcohols, especially methanol and / or ethanol, ethers, esters, ketones, and amides, for example, N-methylpyrrolidone, N-ethylpyrrolidone, dimethylformamide, toluene, xylene, butanol, ethyl glycol, butyl glycol and 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).

[0029] Preferably, the amount of constituent a1) in component (A) is in the range of 10 to 80% by mass, more preferably 25 to 75% by mass, even more preferably 40 to 70% by mass, in each case based on the total mass of component A).

[0030] Constituent a2) Component a1) is at least one polymer containing a functional group 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), such as 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 component of a coating composition 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. The main binder in the meaning of the present invention preferably refers to a binder component that is present in a higher proportion based on the total mass of the coating composition or the components when no other binder components are present in the components used for the coating composition or its preparation.

[0031] 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.

[0032] When component a2) is at least one OH-functional polymer, it preferably contains on average two or more OH groups.

[0033] Any type of polymer having a functional group reactive towards NCO groups can be used as component a2). Examples include (meth)acrylic polymers, polyesters, polyurethanes, polyureas, polyethers, and mixtures thereof.

[0034] Preferably, component a2) is at least one OH-functional (meth)acrylic polymer, more preferably at least one OH-functional (meth)acrylic polymer modified with at least one chlorinated polyolefin. Examples of such polymers include Acrydic® CL-408.

[0035] Preferably, component A) of the primer coating system is present 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, even more preferably 17.5 to 35.0% by mass, based in each case on the total mass of component A), and contains at least one component a2).

[0036] Component a3) Component a3) can be obtained at least by the reaction of (i) at least one organosilane having at least one hydrolyzable group and (ii) at least one silica, and is preferably at least one condensation product obtainable by this reaction. The condensation product a3) is also referred to herein as the "condensate". The condensation product a3) has been found to provide excellent water vapor barrier properties to the cured coating film of the primer coating composition obtainable by mixing components A), B), and optionally C) with each other.

[0037] Preferably, the molar ratio of at least one organosilane to at least one silica used in the preparation of the condensation product a3) 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, even more preferably 4:1 to 1:1, even more preferably 4:1 to 1.1:1, even more preferably 4:1 to 1.5:1, and most preferably 4:1 to 2:1.

[0038] Preferably, at least one condensation product a3) is present in component A) 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, even more preferably 4.0 to 15.0% by mass, even 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, in each case based on the total mass of component A).

[0039] Preferably, the condensation product a3) 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, even more preferably 25 to 60 nm, even more preferably 30 to 50 nm, and most preferably 35 to 45 nm, as measured by DLS (dynamic light scattering) in each case. The DLS method used is defined in the "Method" section below. Preferably, the average particle size is measured at a high shear viscosity of 5 to 15 cP measured using a CAP2000 viscometer.

[0040] The term "silica" as used in this context is a term clear to those skilled in the art and refers to SiO 2 Preferably, at least one silica used is preferably in the form of an aqueous dispersion of colloidal silica particles, 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 defined in the "Method" section below and is the same as the method used for determining the average particle size of the condensation product a3).

[0041] As outlined herein, both acidic colloidal silica dispersions and basic colloidal silica dispersions can be used. However, colloidal silica dispersions with a low alkali content are preferred.

[0042] 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® HS 40 (Sigma-Aldrich), Levasil 200 / 30 and Levasil® 200 S / 30 (now Levasil CS30-516P) (AkzoNobel), and Cab-OSperse® A205 (Cabot Corporation), etc.

[0043] At least one organosilane having at least one hydrolyzable group is preferably an organic, preferably aliphatic residue having 1 to 10 carbon atoms, and optionally further contains at least one non-hydrolyzable group optionally containing at least one functional group, preferably containing it.

[0044] Preferably, at least one organosilane having at least one hydrolyzable group is a monosilane, has at least 2, particularly preferably at least 3, hydrolyzable groups X, and / or is at least one bis(silane), preferably having at least 4, particularly preferably 6, hydrolyzable groups X. However, it is also possible to use a monosilane having 4 hydrolyzable groups X, i.e., a monosilane that does not contain non-hydrolyzable residues such as tetramethoxysilane and / or tetraethoxysilane.

[0045] Preferably, at least one organosilane having at least one hydrolyzable group is an organosilane of 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), 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, R is preferably a non-hydrolyzable organic residue having 1 to 10 carbon atoms, preferably an aliphatic residue, and at least one of the residues R optionally contains at least one functional group, in the case of general formula (2), X represents a hydrolyzable group, independently of one another in each case, preferably independently of one another in each case, selected from O-C 1~4 -alkyl, RA is preferably a divalent non-hydrolyzable organic residue having 1 to 10 carbon atoms, preferably an aliphatic residue, which preferably does not contain a functional group, the parameter z is in each case an integer in the range of 0 or 1 to 3, preferably in each case 0 or 1, more preferably in each case 1, T is preferably a non-hydrolyzable organic residue having 1 to 10 carbon atoms, which is different from the residue RA and optionally contains at least one functional group, preferably an aliphatic residue.

[0046] Examples of suitable functional groups include, 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, where R 3 is preferably an aliphatic residue having from 1 to 10 carbon atoms).

[0047] Examples of suitable organosilanes having at least one non-hydrolyzable group include, 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.

[0048] Preferably, the condensation reaction of at least one organosilane having at least one hydrolyzable group with at least one silica is carried out in an aqueous medium and is preferably catalyzed by at least one preferably organic acid.

[0049] Preferably, at least one 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 based on the molar amount of at least one organosilane, preferably in the presence of at least one acid in a catalytic amount, more preferably at least one organic acid such as acetic acid. The addition is preferably carried out at a temperature of 0 to 10 °C. The resulting mixture is preferably stirred at room temperature (18 to 23 °C) for 10 to 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. The resulting mixture is then preferably stirred for 1 to 10 hours. Preferably, the pH value of the mixture is maintained at a pH of 3 to 6. Then, preferably, the resulting mixture is diluted with at least one water-miscible organic solvent such as isopropanol (IPA) at a mass ratio of, for example, 1:1.

[0050] A schematic of the preparation of an exemplary condensation product a3) prepared from methyltrimethoxysilane (MTMS) as an organic silane is shown in Figure 2.

[0051] Constituents a4) and a5) Preferably, component A) of the primer coating system further comprises at least one catalyst a4) suitable for crosslinking Si-containing functional groups, and catalyst a4) is different from each of components a1) to a3).

[0052] Preferably, at least one catalyst a4) is suitable for crosslinking Si-containing functional groups present in component b3) of component B) when component b3) is present.

[0053] Preferably, component A) of the primer coating system contains at least one catalyst a4) in an amount in the range of 0.01 to 2.5% 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 even more preferably 0.05 to 1.0% by mass, based on the total mass of component A) in each case.

[0054] Preferably, at least one catalyst a4) is a phosphorus-containing catalyst and / or a phosphorus-containing and nitrogen-containing catalyst. Two or more, for example, two different catalysts can be used as catalyst a4).

[0055] Examples of suitable phosphorus-containing catalysts preferably include 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 particularly, at least one catalyst a4) preferably includes substituted phosphoric acid monoesters and phosphoric acid diesters selected from the group consisting of acyclic phosphoric acid monoesters and monoesters, and cyclic phosphoric acid monoesters and monoesters, and in each case, substituted phosphoric acid monoesters and phosphoric acid diesters which may be, for example, amine adducts of phosphoric acid monoesters and diesters are used.

[0056] Examples of such amine adducts include phosphate esters blocked with the corresponding amines, among which, in particular, ethylhexyl phosphate blocked with an amine and phenyl phosphate blocked with an amine, and very preferably bis(2-ethylhexyl) phosphate blocked with an amine. Examples of amines that block phosphate esters are, in particular, tertiary amines, examples of which are, for example, bicyclic amines such as diazabicyclooctane (DABCO), diazabicyclononene (DBN), diazabicycloundecene (DBU), dimethyldodecylamine or triethylamine. Particularly preferred for blocking phosphate esters is the use of tertiary amines that guarantee a high activity of the catalyst under curing conditions. Phosphoric acid catalysts blocked with specific amines are also commercially available (for example, those of the Nacure type from King Industries, such as Nacure® 4167).

[0057] Preferably, at least one catalyst a4) is selected from phosphorus-containing organic constituents, more preferably from acyclic phosphoric acid diesters, acyclic phosphoric acid monoesters, cyclic phosphoric acid diesters and cyclic phosphoric acid monoesters, where each of the aforementioned phosphoric acid diesters and monoesters can optionally be present in the form of an adduct with at least one amine, preferably at least one tertiary amine (i.e., blocked with at least one amine), and even more preferably, at least two catalysts are present as at least one catalyst a4), both of which 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 of these at least two catalysts is not present as an amine adduct (i.e., in an unblocked form).

[0058] Preferably, at least phosphoric acid 2-ethylhexyl ester is used as at least one catalyst a4), in particular in a form that does not exist as an amine adduct, i.e., in a form that is not blocked by an amine, as at least one catalyst a4). The term "2-ethylhexyl acid phosphate" includes both mono-ethylhexyl phosphate and di-ethylhexyl phosphate.

[0059] 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. Preferably, the relative mass ratio to each other of the catalyst not present in the form of an amine adduct and the catalyst present in the form of an amine adduct within component A) is in the range of 0.1:1.0 to 0.9:1.0, more preferably 0.2:1.0 to 0.8:1.0, even more preferably 0.3:1.0 to 0.7:1.0.

[0060] Preferably, there are at least two types of catalysts a4), one catalyst does not exist in the form of an amine adduct such as phosphoric acid 2-ethylhexyl ester, preferably exists in an amount in the range of 0.01 to 0.4% by mass, and one catalyst exists in the form of an amine adduct, preferably exists in an amount in the range of 0.05 to 1.0% by mass.

[0061] Preferably, component A) of the primer coating system contains a catalyst present in the form of an amine adduct 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, even more preferably 0.08 to 1.4% by mass, even more preferably 0.09 to 1.2% by mass, particularly preferably 0.10 to 1.0% by mass, based on the total mass of component A) in each case.

[0062] Preferably, component A) of the primer coating system contains a catalyst that does not exist in the form of an amine adduct 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, even more preferably 0.04 to 0.5% by mass, even more preferably 0.05 to 0.4% by mass, based on the total mass of component A) in each case.

[0063] Preferably, component A) of the primer coating system further contains at least one catalyst a5) suitable for crosslinking of NCO groups, and catalyst a5) is different from catalyst a4) and also different from each of components a1) to a3).

[0064] Preferably, at least one catalyst a5) is suitable for crosslinking of the NCO groups of component b2) of component B).

[0065] Preferably, component A) of the primer coating system contains at least one catalyst a5) 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, even more preferably 0.004 to 0.40% by mass, even more preferably 0.005 to 0.20% by mass, most preferably 0.007 to 0.15% by mass, based on the total mass of component A) in each case.

[0066] Preferably, catalyst a5) is selected from organometallic catalysts, particularly organotin catalysts. Examples of organotin catalysts are DOTL (dioctyltin dilaurate) and DBTL (dibutyltin dilaurate). DOTL is particularly preferred.

[0067] Further components Component A) of the primer coating system can optionally contain one or more additional components that are different from each other, different from each of components a1) to a3), and also different from each of optional components a4) and a5), such as one or more of components a6) to a8). 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).

[0068] Preferably, component A) of the primer coating system is As component a6), in each case, based on the total mass of component A), an amount in the range of preferably 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, of at least one epoxy resin, and / or As component a7), in each case, based on the total mass of component A), an amount in the range of preferably 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, of at least one chlorinated polyolefin, and / or As component a8), in each case, based on the total mass of component A), an amount of preferably 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, still more preferably 8.0 to 15% by mass, of at least one pigment and / or filler and contains.

[0069] The term "pigment" is known to those skilled in the art, for example, from DIN 55943 (date: October 2001). "Pigment" in the meaning of the present invention preferably refers to a powdery or flaky constituent that is substantially, preferably completely insoluble in the medium surrounding them, such as in one of the coating compositions used in the present invention. Pigments are preferably substances that can be used as pigments due to their coloring agents and / or their magnetic, electrical and / or electromagnetic properties. Pigments preferably differ from "fillers" in their refractive index, and the refractive index of pigments is ≧1.7. The term "filler" is known to those skilled in the art, for example, from DIN 55943 (date: October 2001). Pigments can be inorganic or organic.

[0070] Component A) of the primer coating system can optionally contain one or more such additional constituents in addition to, or in place of, one or more constituents a6) to a8). Depending on the desired application, component A) can contain one or more commonly used additives. For example, it can contain at least one additive selected from the group consisting of reactive diluents, light stabilizers, antioxidants, defoamers, emulsifiers, slip additives, polymerization inhibitors, plasticizers, free radical polymerization initiators, adhesion promoters, flow control agents, 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 contents based on the total mass of the coating composition obtained by mixing components A), B), and optionally C) are, in each case, based on the total mass of the coating composition, 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.

[0071] In particular, component A) of the primer coating system optionally contains at least one leveling agent and / or dispersant as additive as component a9). Preferably, a9) is a (meth)acrylate polymer preferably containing at least one ether segment(s) in the side chain and / or preferably also at least one siloxane unit in the side chain. Preferably, component a9) is present in component A) in the range of 0.10 to 5.0% by mass, more preferably 0.50 to 4.0% by mass, even more preferably 0.80 to 3.5% by mass, based on the total mass of component A) in each case.

[0072] Component B) Component B) contains at least two different components b2) and optionally component b1), but may further contain any other components.

[0073] Preferably, component B) does not contain condensate a3), that is, condensate a3) is present only in component A) of the primer coating system.

[0074] 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, still more preferably >55% by mass, based on the total mass of component B) respectively. The total solids content of component B) of the primer coating system is preferably in the range of 45 to 100% by mass, more preferably 50 to <100% by mass, even more preferably 55 to <100% by mass, based on the total mass of component B) respectively. The total solids content, in other words the non-volatile fraction, is determined according to the method described below.

[0075] Optional component b1) Any constituent b1) is at least one organic solvent. Examples of such organic solvents include those already described herein 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 two or more organic solvents are used as a1) and / or b1), both a1) and b1) may be partially the same and partially different.

[0076] 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, and even more preferably 15 to 35% by mass, based on the total mass of component B) in each case.

[0077] Constituent b2) Constituent b2) is an organic constituent having on average two or more NCO groups. Preferably, constituent b2) has on average two or more NCO groups.

[0078] Preferably, at least one organic component 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 of IPDI (isophorone diisocyanate) and / or HDI (hexamethylene diisocyanate), i.e., isocyanurates, are particularly preferred.

[0079] 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 polyisocyanate. 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 also mixtures of the aforementioned polyisocyanate parent structures. Particularly preferred polyisocyanate parent structures are hexamethylene diisocyanate and / or its isocyanurate trimer, optionally together with its uretdione.

[0080] 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.

[0081] 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 an NCO - group - containing component having silane - modified NCO groups.

[0082] Component b3) Optionally, component B) of the primer coating system 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. Preferably, component b3) is used as an adhesion promoter.

[0083] 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 preferably at least one bis(silane) having at least four, particularly preferably six, hydrolyzable groups X.

[0084] Preferably, at least one organosilane is an organosilane of 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), where, in the case of 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 0 or 1 to 3, preferably at least 1, preferably exactly 1, R is a non-hydrolyzable organic residue, preferably an aliphatic residue, having preferably 1 to 10 carbon atoms, and at least one of the residues R optionally contains at least one functional group, in the case of general formula (II), X represents, in each case independently of one another, a hydrolyzable group, preferably, in each case independently of one another, selected from O-C 1~4 -alkyl, RA represents a divalent non-hydrolyzable organic residue, preferably an aliphatic residue, having preferably from 1 to 10 carbon atoms and preferably containing no functional groups. The parameter z is an integer in the range from 0 to 3 in each case, preferably 0 in each case. T is a non-hydrolyzable organic residue, preferably an aliphatic residue, having preferably from 1 to 10 carbon atoms and, unlike the residue RA, optionally containing at least one functional group.

[0085] Examples of suitable functional groups are in particular thiol groups, amino groups and epoxide groups.

[0086] 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.

[0087] Optional 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 thus contains at least one organic solvent c1), preferably consisting of at least one organic solvent c1). Examples of such organic solvents include those already mentioned herein in connection with components a1) and b1). Component C) may contain two or more 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 two or more organic solvents are used as a1) and / or b1) and / or c1), a1) and / or b1) and / or c1) may be partially the same and partially different.

[0088] Primer coating composition The primer coating composition is obtained by mixing at least components A), B), and optionally C) of the primer coating system with each other (Option 1), or is a primer coating composition (Option 2), where this primer coating composition comprises at least components (i), (ii), and (iii), and optionally (iv), which are different from each other, i.e., (i) at least one organic solvent, preferably corresponding to at least one of the organic solvents a), b1), and / or c1) defined for the primer coating system of the present invention, (ii) at least one film-forming polymer corresponding to at least one polymer a2) that is self-crosslinkable or externally crosslinkable, preferably externally crosslinkable, and more preferably contains a functional group that is reactive towards the NCO group as defined for the primer coating system of the present invention, (iii) at least one condensation product corresponding to the condensation product a3) defined for the primer coating system of the present invention, and (iv) Optionally, when at least one film-forming polymer (ii) is an externally crosslinkable polymer, at least one crosslinking agent, preferably selected from blocked polyisocyanates, melamine formaldehyde resins, and mixtures thereof is included.

[0089] The preparation of the coating composition of the first option can be carried out using conventional and known preparation and mixing methods and mixing units, or using conventional dissolvers and / or stirrers.

[0090] All preferred embodiments described herein in connection with the primer coating system and its preferred embodiments are also preferred embodiments of the primer coating composition.

[0091] Preferably, the primer coating composition is a solvent-based system, i.e., based on an organic solvent(s), due to the presence of components a1), b1), and optionally c1). The term "solvent-based" in relation to the coating composition preferably means, for the purposes of the present invention, that the aforementioned organic solvent(s) is / are the main component(s) of all solvents and / or diluents present therein, preferably in an amount of at least 35% by mass based on the total mass of the coating composition. Thus, preferably, the coating composition is not an aqueous system, i.e., an aqueous coating composition. The primer coating composition preferably contains organic solvent(s) in a proportion of at most 75% by mass, more preferably at most 70% by mass, even more preferably at most 65% by mass, and even more preferably at most 60% by mass, in each case based on the total mass of the coating composition. All conventional organic solvents 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 known to those skilled in the art, in particular from Council Directive 1999 / 13 / EC of 11 March 1999. Examples of organic solvents that can be used are described above in this specification in relation to components a1), b1), and c1). Preferably, the primer coating composition contains organic solvent(s) in a proportion in the range of 30 to 70% by mass based on the total mass of the coating composition.

[0092] Preferably, the primer coating composition has a total solids content that is > 25% by mass, more preferably > 30% by mass, even more preferably > 35% by mass, in each case based on the total mass of the coating composition.

[0093] 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, in each case based on 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.

[0094] Preferably, the primer coating composition can be 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 particularly preferably in the range of 15:1 to 3:1.

[0095] Preferably, when the primer coating composition is applied onto a primer coating film obtained from the primer coating composition on a substrate, preferably onto an intermediate coating film, more preferably a basecoat film, at least partial curing of the intermediate coating film is achieved by including an excess of component b2) having on average two or more NCO groups, and the intermediate coating film includes at least one preferably polymeric component including functional groups reactive towards NCO groups. The term "excess" in this context preferably means a molar excess or a mass excess, more preferably a mass excess.

[0096] The term "excess component b2)" preferably means that, in each case, based on the total mass of component b2) originally present in component B), 5 to 20% by mass, preferably 7.5 to 15% by mass, more preferably 10 to 12.5% by mass of component b2) derived from component "B" remains in the primer coating composition obtained after mixing, where this amount is not used for crosslinking with related components such as component a2) of component A) by using component b) in an overstoichiometric amount. Thereby, when applying onto a primer coating film obtained by applying the primer coating composition onto a substrate surface, it is also possible to at least partially cure the subsequently applied basecoat film via NCO migration.

[0097] The primer coating composition according to the second alternative is a 1K (one-component) coating composition, which does not require mixing of its components until immediately before application in the case of the primer coating system of the present invention. Preferably, the 1K primer coating composition of the second alternative does not contain free polyisocyanate, i.e., a component having unblocked NCO groups.

[0098] The 1K primer coating composition of the second alternative contains at least one organic solvent as component (i). The same solvents as defined herein for components a1), b1) and c1) can also be used as component (i).

[0099] The 1K primer coating composition of the second alternative can contain any of the additional components defined herein as being present as components in component A) of the primer coating system, for example, including any of components a4) to a9). All of the preferred embodiments described above herein in connection with any of these components present in the primer coating system are also preferred embodiments when present in the 1K primer coating composition of the second alternative.

[0100] The 1K primer coating composition of the second alternative contains at least one condensation product as component (iii), which corresponds to condensation product a3) previously defined herein for the primer coating system of the present invention. All of the preferred embodiments described above herein in connection with condensation product a3) present in the primer coating system are also preferred embodiments of condensation product a3) present in the 1K primer coating composition of the second alternative.

[0101] Preferably, at least one condensation product a3) 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, even more preferably 4.0 to 15.0% by mass, even 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, based on the total mass of the primer coating composition.

[0102] The one-component primer coating composition of the second alternative comprises at least one film-forming polymer, which is self-crosslinkable or externally crosslinkable, preferably externally crosslinkable, more preferably corresponding to at least one polymer a2), and this polymer contains a functional group that is reactive with respect to the NCO group as defined for the primer coating system of the present invention. Optionally, when at least one film-forming polymer (ii) is an externally crosslinkable polymer, it further comprises at least one crosslinking agent. The at least one crosslinking agent is preferably selected from blocked polyisocyanates, melamine formaldehyde resins, and mixtures thereof. All preferred embodiments described hereinabove in connection with polymer a2) present in the primer coating system are also preferred embodiments of the polymer component (ii) present in the one-component primer coating composition of the second alternative.

[0103] Method of using the primer coating composition A further subject of the present invention is a method of using the primer coating composition of the present invention for improving the water resistance and / or moisture resistance of a cured primer coating film obtainable therefrom and / or a cured multilayer coating system comprising at least one cured primer coating film, wherein the cured primer coating film is obtained from the primer coating composition. This improvement is considered to be particularly due to the presence of component a3).

[0104] All preferred embodiments described hereinabove in connection with the primer coating system and the primer coating composition, and in each case their preferred embodiments, are also preferred embodiments of the aforementioned method of use.

[0105] Method of coating a substrate A further subject of the present invention is at least step 1) and optional step (1a), namely 1) Applying at least partially the primer coating composition of the present invention to at least one surface of an optionally pre-coated substrate to form a primer coating film on said surface, and 1a) Optionally, at least one further step 1a) of curing at least one primer coating film obtained after step 1) to obtain at least one cured primer coating layer on said surface A method of coating a substrate, comprising.

[0106] All preferred embodiments described herein in connection with the primer coating system, primer coating composition, and the aforementioned use method, and in each case those preferred embodiments are also preferred embodiments of the aforementioned method.

[0107] Preferably, step 1) is carried out by spraying.

[0108] The primer coating film formed on the optionally pre-coated substrate by performing step 1) is an uncured coating film at this stage. The term "primer" is known to those skilled in the art. A primer is usually applied after providing a cured electrodeposited coating layer on the substrate, in the case of a metal substrate. In this case, the cured electrodeposited coating film is present under, 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 usually represents the first coating film applied to its surface.

[0109] Preferably, step 1a) 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, still more preferably in the range of 40 to 130°C, and in each case preferably for 5 to 45 minutes, more preferably for 10 to 40 minutes, particularly preferably for 12.5 to 35 minutes, and most preferably for 15 to 30 minutes. Most preferably, particularly when a plastic substrate or a fiber-reinforced plastic substrate is used, step 1a) 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. Before step 1a), the primer coating film may optionally be flash-off for preferably 1 to 20 minutes, more preferably 1.5 to 15 minutes, even more preferably 2 to 12 minutes, even more preferably 5 to 11 minutes, and most preferably 8 to 10 minutes. Preferably, the flash-off is carried out at a temperature not exceeding 40°C, more preferably in the temperature range of 18 to 30°C.

[0110] The term "flash-off" in the context of the present invention means drying in which at least a part of the solvent and / or water evaporates from the coating film (i.e., from the primer coating film being formed) before curing. Curing is not carried out by flash-off.

[0111] Preferably, the cured primer film (primer layer L1) obtained after step 1a) has a dry film thickness in the range of 10 to 35 μm.

[0112] This method is particularly suitable for coating automotive bodies or parts thereof, including not only each metal substrate but also plastic substrates such as polymer substrates and fiber-reinforced plastic substrates. Therefore, preferred substrates are automotive bodies or parts thereof.

[0113] Suitable as the metal substrate used according to the present invention are all substrates that are conventionally used and known to those skilled in the art. The substrate used according to the present invention is preferably, 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 (for example, galvalume, galvanneal or galfan), and aluminized steel, aluminum and magnesium, and further a metal substrate selected from steel selected from the group consisting of Zn / Mg alloys and Zn / Ni alloys. Particularly suitable substrates are a part of an automobile body or a completed automobile body for production. The metal substrate may be pretreated with at least one metal phosphate such as zinc phosphate and / or pretreated with at least one oxalate. This type of pretreatment by phosphate treatment or oxalate treatment is usually carried out after the substrate is washed and before the substrate is electrocoated, and is a pretreatment process particularly commonly used in the automobile industry. The metal substrate may further include a cured electrocoating layer as a precoat.

[0114] Preferably, a thermoplastic polymer is used as the plastic substrate. Suitable polymers include poly(meth)acrylates, such as polymethyl(meth)acrylate, polybutyl(meth)acrylate, polyethylene terephthalate, polybutylene terephthalate, polyvinylidene fluoride, polyvinyl chloride, polyesters, such as polycarbonate and polyvinyl acetate, polyamides, polyolefins, such as polyethylene, polypropylene, polystyrene, and also polybutadiene, polyacrylonitrile, polyacetal, polyacrylonitrile-ethylene-propylene-diene-styrene copolymer (A-EPDM), ASA (acrylonitrile-styrene-acrylic ester copolymer) and ABS (acrylonitrile-butadiene-styrene copolymer), polyetherimide, phenolic resin, urea resin, melamine resin, alkyd resin, epoxy resin, polyurethane, such as TPU, polyether ketone, polyphenylene sulfide, polyether, polyvinyl alcohol, and mixtures thereof. Polycarbonate and poly(meth)acrylate are particularly preferred.

[0115] Furthermore, most preferably, a fiber-reinforced plastic substrate is used. Glass fibers and / or carbon fibers, most preferably carbon fibers, can be used especially for reinforcement. An example of a suitable carbon fiber-reinforced plastic substrate is a carbon fiber-reinforced polyamide substrate.

[0116] Coated substrate A further subject of the present invention is a coated substrate obtainable by the said method.

[0117] The primer coating system, the primer coating composition, all the preferred embodiments described hereinabove in connection with the said use method and method, and in each case their preferred embodiments are also preferred embodiments of the coated substrate.

[0118] Method for preparing a multilayer coating system A further subject of the present invention is at least steps 1) to 3) and optionally 4), namely 1) A step of applying at least partially a first coating composition to at least one surface of an optionally pre-coated substrate to form a first coating film on said surface, wherein the first coating composition is the said primer coating composition, 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, 3) On the second coating film present on the substrate obtained after step 2), preferably before curing the second coating film, apply a topcoat composition, preferably a clearcoat composition, as the third coating composition, preferably adjacent to the second coating film and preferably forming the outermost coating film of the multilayer coating system to be formed, a step of forming a third coating film; 4) Optionally, co-curing the first, second and third coating films to obtain a multilayer coating system comprising cured first, second and third coating layers A method for preparing a multilayer coating system on at least one surface of an optionally pre-coated substrate, comprising:

[0119] The primer coating system, the primer coating composition, the aforementioned use methods and methods, and all preferred embodiments described herein in connection with the coated substrate, and in each case those preferred embodiments are also preferred embodiments of the method for preparing a multilayer coating system.

[0120] The method includes at least steps (1), (2), (3) and optionally (4). However, the method may further include additional optional steps.

[0121] Preferably, each of steps 1) to 3) is performed by spray coating.

[0122] The first, second and third coating films formed on the optionally pre-coated substrate by performing steps 1), 2) and 3) are preferably uncured coating films at this stage. Therefore, preferably, the first coating composition, the second coating composition and the third coating composition are applied wet-on-wet.

[0123] Preferably, the method of the present invention further includes step 1b) which is carried out after step 1) and before step 2). In the said step 1b), the first coating film obtained after step 1) is preferably flashed off for a period of 1 to 20 minutes, more preferably for a period of 1.5 to 15 minutes, even more preferably for a period of 2 to 12 minutes, even more preferably for a period of 5 to 11 minutes, and most preferably for a period of 8 to 10 minutes before applying the second coating composition in step 2). Preferably, step 1b) is carried out at a temperature not exceeding 40°C, more preferably at a temperature in the range of 18 to 30°C.

[0124] The second coating film is a basecoat film. Accordingly, the second coating composition is a basecoat composition. The term "basecoat" is known to those skilled in the art and is defined, for example, in Roempp Lexikon, paint and printing inks, Georg Thieme Verlag, 1998, 10th edition, page 57. Accordingly, basecoats are used, particularly in automotive and general industrial coatings, to impart color and / or optical effects by using the basecoat as an intermediate coating composition. Basecoats are generally applied to metal or plastic substrates, both of which are optionally pre-coated. At least one additional topcoat, preferably a clearcoat film, is applied, particularly to protect the basecoat film from environmental influences. The terms "clearcoat", "clear coat" or "clear coating" are also known to those skilled in the art and represent the transparent outermost layer of a multilayer coating structure applied to a substrate.

[0125] Preferably, this method further includes step 2a) which is carried out after step 2) and before step 3). In said step 2a), the second coating film obtained after step 2) is preferably flashed off for a period of 1 to 20 minutes, more preferably for a period of 1.5 to 15 minutes, even more preferably for a period of 2 to 12 minutes, even more preferably for a period of 5 to 11 minutes, and most preferably for a period of 8 to 10 minutes before applying the third coating composition in step 3). Preferably, step 2a) is carried out at a temperature not exceeding 40°C, more preferably in the temperature range of 18 to 30°C.

[0126] Preferably, this 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 preferably flashed off for a period of 1 to 20 minutes, more preferably for a period of 3 to 15 minutes, particularly preferably for a period of 7 to 12 minutes before carrying out 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.

[0127] In step 4), the first, second and third coating films are cured jointly, i.e., cured together simultaneously. The cured third coating film preferably represents the outermost layer of the formed multilayer coating system obtained after step 4).

[0128] Each obtained cured coating film represents a coating layer. Therefore, after carrying out 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.

[0129] 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. In any case, it is preferably carried out for 5 to 45 minutes, more preferably for 10 to 40 minutes, particularly for 12.5 to 35 minutes, and most preferably for 15 to 30 minutes. Most preferably, particularly 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 in any case the substrate temperature and is preferably measured with a thermocouple.

[0130] Preferably, the cured primer film (layer L1) obtained after carrying out 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 carrying out step 4) has a dry film thickness in the range of 12 to 35 μm. Preferably, the cured top coat, particularly the clear coat film (layer L3) obtained after carrying out step 4) has a dry film thickness in the range of 30 to 60 μm.

[0131] Base coat and top coat compositions In step 2), any type of base coat composition can be used, for example, a 1K or 2K base coat composition, preferably a 1K composition, which can be solvent-based or water-based and may contain coloring pigments and / or effect pigments. Preferably, the base coat composition contains at least one film-forming binder, preferably at least one polymer, more preferably at least one polymer having a functional group reactive with respect to the NCO group. Optionally, particularly when at least the film-forming binder is an externally crosslinkable polymer, the base coat composition can contain at least one crosslinking agent, preferably a crosslinking agent selected from melamine formaldehyde resins and / or preferably blocked polyisocyanates.

[0132] In step 3), any type of topcoat, preferably a clearcoat composition, such as a 1K or 2K basecoat composition, preferably a 2K composition, can be used, which can be solvent-based or water-based, but is preferably solvent-based.

[0133] Preferably, each clearcoat composition obtained from a suitable clearcoat coating system comprising a 2K clearcoat composition, more preferably at least two components D) and E) that are different from each other and separate from each other, and optionally at least one further component F) is used. Preferably, component D) comprises at least constituent components d1) to d4) that are different from each other, namely at least one organic solvent d1), at least one OH-functional (meth)acrylic polymer d2), and at least one OH-functional (meth)acrylic polymer d2) having a glass transition temperature (T g ) lower than the glass transition temperature (T g ) of at least one OH-functional (meth)acrylic polymer d3) (wherein the amount of constituent component d2) in component D) exceeds the amount of constituent component d3)), and at least one catalyst d4) suitable for crosslinking with NCO groups. Preferably, component E) comprises at least two constituent components e1) and e2) that are different from each other, namely at least one organic solvent e1), and at least one organic component e2) having on average two or more NCO groups, wherein at least some of these NCO groups have been reacted with at least one organosilane before incorporating constituent component e2) into component E), and optional component F) is a reducing agent component and comprises at least one organic solvent f1). Preferably, both components D) and E) of the clearcoat coating system, and optionally F), are transparent, i.e., clear. Preferably, of course, the resulting clearcoat composition is also transparent, i.e., clear. In particular, none of components D), E), and optionally F) of the coating system contains pigments and / or fillers, especially pigments and / or fillers that impart color and / or effect. Of course, preferably, the same also applies to the clearcoat composition.

[0134] Constituent component d1) Component d1) is at least one organic solvent. Examples of such organic solvents include those already mentioned herein in connection with components 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) may be partially the same as or different from b1) and / or c1) and / or d1).

[0135] Components d2) and d3) Component d2) is at least one OH-functional (meth)acrylic polymer. Component d3) is also at least one OH-functional (meth)acrylic polymer, but is different from d2). 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). The amount of component d2) in component D) exceeds the amount of component d3), that is, the (meth)acrylic polymer d2) having a higher T g ((higher than the (meth)acrylic polymer d3)) is present in component D) in a higher amount than the (meth)acrylic polymer d3). T g is measured according to the method disclosed in the "Method" section. g

[0136] 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) and preferably at least one OH-functional (meth)acrylic polymer d3) present in component D) of the clear coat system has a glass transition temperature (T in the range of +10 °C to +75 °C, preferably +15 °C to +70 °C, more preferably -50 °C to 0 °C, even more preferably -45 °C to 0 °C, still more preferably -40 °C to 0 °C, still more preferably -35 °C or -30 °C to 5 °C, most preferably -25 °C or 5 °C. g ) and has.

[0137] The OH-functional (meth)acrylic polymers d2) and d3) preferably each contain on average 2 or more OH groups. Preferably, each of the OH-functional (meth)acrylic polymers d2) and d3) has an OH number of 30 to 400 mg KOH / g, more particularly 100 to 300 KOH / g. Preferably, each of components d2) and d3) has a mass average molecular weight M measured by gel permeation chromatography (GPC) against polystyrene standards in the range of preferably 800 to 100,000 g / mol, more particularly 1000 to 75,000 g / mol. w and has.

[0138] The term "(meth)acrylic polymer" in each case includes both homopolymers and copolymers, but preferably means a copolymer.

[0139] In the context of the present invention, the terms “(meth)acrylic” or “(meth)acrylate” or “(meth)acrylic-based” each include, in each case, the meaning of “methacrylic” and / or “acrylic”, “methacrylic-based” and / or “acrylic-based” or “methacrylate” and / or “acrylate”. Thus, generally, a “(meth)acrylic copolymer” can be formed from only “acrylic monomers”, only “methacrylic monomers”, or “acrylic monomers and methacrylic monomers”. However, the “(meth)acrylic copolymer” may include polymerizable monomers other than acrylic monomers and / or methacrylic monomers, such as styrene and the like. In other words, a (meth)acrylic copolymer may consist of only acrylic monomer and / or methacrylic monomer units, but it does not have to be so. The notations “(meth)acrylate polymer or copolymer” or “(meth)acrylic polymer or copolymer” are intended to mean that the polymer / copolymer (polymer backbone / main chain) is mainly, i.e., preferably more than 50% or more than 75% of the monomer units used, formed from monomers having a (meth)acrylate group. Thus, in the preparation of a (meth)acrylic copolymer, preferably more than 50% or more than 75% of the monomers have a (meth)acrylate group. However, the use of additional monomers as comonomers, such as copolymerizable vinyl monomers, such as styrene, etc., for its preparation is not excluded.

[0140] To introduce the OH functionality, hydroxyl-containing monomers such as hydroxyalkyl esters of acrylic acid 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 of these with epsilon-caprolactone, and other hydroxyalkyl-(meth)acrylates having a branched or straight-chain alkyl group having about 10 or fewer carbon atoms, and mixtures thereof, where the term "(meth)acrylate" refers to either or both of methacrylate and acrylate esters. Generally, it is preferred that at least about 5% by weight of the hydroxyl-functional monomer be included in the polymer. Hydroxyl groups on vinyl polymers such as acrylic polymers can be generated by other means, such as ring-opening of glycidyl groups from copolymerized glycidyl methacrylate with an organic acid or amine.

[0141] The hydroxyl functionality can also be introduced through thioalcohol compounds such as 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 (which are not limited). Using any of these methods, useful hydroxyl-functional (meth)acrylic polymers can be prepared.

[0142] Examples of suitable comonomers used include 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, aromatic or heterocyclic aliphatic vinyl compounds, but are not limited thereto. Representative examples of suitable esters of acrylic acid, methacrylic acid, and crotonic acid include esters formed by reaction with 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; unsaturated dicarboxylic acids and anhydrides, such as fumaric acid, maleic acid, itaconic acid, and anhydrides, and mono- and diesters thereof with alcohols such as methanol, ethanol, propanol, isopropanol, butanol, isobutanol, tert-butanol, etc., 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.

[0143] (Meth)acrylic polymers can be prepared using conventional techniques such as heating the monomers in the presence of a polymerization initiator and optionally a chain transfer agent. The polymerization can be carried out, for example, in solution. Representative polymerization 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. Representative 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 dimer α-methylstyrene.

[0144] The polymerization reaction is usually carried out at a temperature of about 20 °C to about 200 °C. It is convenient to carry out the reaction at a temperature at which the solvent or solvent mixture refluxes, but if appropriately controlled, a temperature below reflux can also be maintained. The initiator should be selected according to the temperature at which the reaction is carried out, and the half-life of the initiator at that temperature should preferably be about 30 minutes or less. Further details regarding general addition polymerization and the polymerization of mixtures containing (meth)acrylate monomers are readily available in the polymer art. The solvent or solvent mixture is generally heated to the reaction temperature, and the monomers and initiator are usually added at a controlled rate over a period of 2 to 6 hours. During this time, a chain transfer agent or additional solvent can also be supplied at a controlled rate. Thereafter, the temperature of the mixture is maintained for a certain time to complete the reaction. Optionally, an additional initiator can be added to ensure complete conversion.

[0145] Component 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, component d2) is present in component D) in an amount in the range of 10.0% to 80.0% by mass, even more preferably 15.0% to 75.0% by mass, in each case based on the total mass of component D). Component 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, component d3) is present in component D) in an amount in the range of 10.0% to 80.0% by mass, even more preferably 15.0% to 75.0% by mass, in each case based on the total mass of component D).

[0146] Constituent d4) Constituent d4) is suitable for crosslinking of NCO groups and is at least one catalyst d4) selected from organotin catalysts. Catalyst d4) may be the same as or different from catalyst a5). Preferably, catalyst d4) and a5) are the same.

[0147] Component D) may contain at least one further organometallic catalyst other than catalyst d4), for example an organobismuth catalyst. However, preferably, if such at least one further organometallic catalyst such as an organobismuth catalyst is further present in component D), its amount is less than the amount of catalyst d4). However, more preferably, component D) does not contain other organometallic catalysts other than catalyst d4), in particular does not contain an organobismuth catalyst. Preferably, at least one catalyst d4) suitable for crosslinking NCO groups, in particular component e2) of component E), is 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, even more preferably 0.20 to 1.25% by mass, most preferably 0.30 to 1.00% by mass, based on the total mass of component D) of the clearcoat system. Catalyst d4) is selected from organotin catalysts. Examples of organotin catalysts are DOTL (dioctyltin dilaurate) and DBTL (dibutyltin dilaurate). DOTL is particularly preferred.

[0148] Any constituent d5) Preferably, component D) of the clearcoat system further contains at least one catalyst d5) suitable for crosslinking preferably Si-containing functional groups, and catalyst d5) is different from each of constituents d1) to d4). Catalyst d5) may be the same as or different from catalyst a4).

[0149] Preferably, at least one catalyst d5) is suitable for crosslinking the Si-containing functional groups present in component e2) of component E).

[0150] 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, even more preferably 1.00 to 4.00% by mass, most preferably 1.10 to 3.75% by mass, based on the total mass of component D).

[0151] 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 catalysts such as two different catalysts can be used.

[0152] Examples of suitable phosphorus-containing catalysts are substituted phosphonic acid diesters and diphosphonic acid diesters, preferably 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 particularly, 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 which may be, for example, amine adducts of phosphoric acid monoesters and diesters are used.

[0153] Examples of such amine adducts include phosphate esters blocked with the corresponding amines, among which, in particular, ethylhexyl phosphate blocked with an amine and phenyl phosphate blocked with an amine, very preferably bis(2-ethylhexyl) phosphate blocked with an amine. Examples of amines that block phosphate esters are, in particular, tertiary amines, examples of which are, for example, bicyclic amines such as diazabicyclooctane (DABCO), diazabicyclononene (DBN), diazabicycloundecene (DBU), dimethyldodecylamine or triethylamine. Particularly preferred for blocking phosphate esters is the use of tertiary amines which ensure high activity of the catalyst under curing conditions. Phosphoric acid catalysts blocked with specific amines are also commercially available (for example, Nacure type from King Industries, for example Nacure® 4167).

[0154] Preferably, at least one catalyst d5) is selected from phosphorus-containing organic constituents, more preferably from acyclic phosphoric acid diesters, acyclic phosphoric acid monoesters, cyclic phosphoric acid diesters and cyclic phosphoric acid monoesters, where each of the aforementioned phosphoric acid diesters and monoesters can optionally be present in the form of an adduct with at least one amine, preferably at least one tertiary amine (i.e., blocked with at least one amine), and even more preferably, at least two catalysts are present as at least one catalyst d5), both of which 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 of these at least two catalysts is not present as an amine adduct (i.e., in unblocked form).

[0155] Preferably, at least two types of catalyst d5) are present, one catalyst is not present in the form of an amine adduct such as phosphoric acid 2-ethylhexyl ester, 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, even more preferably 0.50 to 2.0% by mass or 0.50 to 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.

[0156] Preferably, at least 2-ethylhexyl acid phosphate is used as at least one catalyst d5), in particular as at least one catalyst d5) that is not present in the form of an amine adduct, i.e., not present in blocked form with an amine. The term "2-ethylhexyl acid phosphate" includes both monoethylhexyl acid phosphate and diethylhexyl acid phosphate.

[0157] Further constituents Component D) can optionally contain one or more further constituents. Depending on the desired application, component D) can contain one or more commonly used additives. For example, reactive diluents, light stabilizers, antioxidants, defoamers, emulsifiers, slip additives, polymerization inhibitors, plasticizers, free radical polymerization initiators, adhesion promoters, flow control agents, film-forming aids, flame retardants, corrosion inhibitors, desiccants, biocides, thickeners, wetting agents, leveling agents and / or matting agents. These can be used in known customary proportions. Preferably, based on the total mass of the coating composition obtained by mixing components D) and E), and optionally F), their contents are, in each case, based on the total mass of the coating composition, 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, in particular from 0.1 to 5.0% by mass, and most preferably from 0.1 to 2.5% by mass.

[0158] Component D) may further contain one or more further (meth)acrylic polymers that are different from both d2) and d3), and these may also be OH-functional, but do not necessarily have to be. Component D) may contain one or more further film-forming polymers that are suitable as binder constituents 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.

[0159] Component E) Component E) contains at least two different components e1) and e2), but may further contain any additional components. Preferably, the components E) of the clearcoat system have a total solids content of >40% by weight, more preferably >45% by weight, even more preferably >50% by weight, and still more preferably >55% by weight, respectively, based on the total mass of component E). The total solids content of component E) of the clearcoat system is preferably in the range of 45 - 100% by weight, more preferably 50 - <100% by weight, and even more preferably 55 - <100% by weight, respectively, in each case based on 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.

[0160] Constituent e1) Constituent e1) is at least one organic solvent. Examples of such organic solvents include those already mentioned herein 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) may be partially the same as and partially different from b1), c1), d1), and / or e1).

[0161] Constituent e2) Constituent e2) is an organic constituent having on average two or more NCO groups, where at least some of these NCO groups have been reacted with at least one organosilane prior to incorporating constituent e2) into component E).

[0162] Examples of constituent e2) are disclosed, for example, in WO 2009 / 077181 A1, WO 2010 / 139375 A1, WO 2010 / 063332 A1, WO 2014 / 086530 A1, and WO 2014 / 086529 A1.

[0163] Preferably, at least one constituent e2) of component E) of the clear coat system has at least one structural unit of formula (I), -NR-(X-SiR’’ x (OR’) 3-x ) (I), and / or, preferably, at least one structural unit of formula (II) -N(X-SiR’’ x (OR’) 3-x ) n (X’-SiR’’ y (OR’) 3-y ) m (II), having wherein R is hydrogen, alkyl, cycloalkyl, aryl or aralkyl, and the carbon chain can be interrupted by non-adjacent oxygen, sulfur or NR a groups, where R a is alkyl, cycloalkyl, aryl or aralkyl, each R’ is independently of one another hydrogen, alkyl or cycloalkyl, and the carbon chain can be interrupted by non-adjacent oxygen, sulfur or NR a groups, preferably each R’ is ethyl and / or methyl, each X, X’ is independently of one another a linear and / or branched alkylene or cycloalkylene radical having 1 to 20 carbon atoms, preferably each X, X’ is an alkylene radical having 1 to 4 carbon atoms, each R’’ is independently of one another alkyl, cycloalkyl, aryl or aralkyl, and the carbon chain can be interrupted by non-adjacent oxygen, sulfur or NR a groups, preferably each R’’ is, more particularly, an alkyl radical having 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.

[0164] Each preferred alkoxy radical (OR’) may be the same or different, but what is decisive for the structure of the radical is how much they affect the reactivity of the hydrolyzable silane group. Preferably, R’ is an alkyl radical having more particularly 1 to 6 carbon atoms. Particularly preferred is a radical R’ that enhances the reactivity of the silane group, i.e., represents a good leaving group. Thus, a methoxy radical is more preferred than an ethoxy radical, and this is more preferred than a propoxy radical. Thus, particularly preferably, R’ is ethyl and / or methyl, more particularly methyl. The reactivity of the organofunctional silane is also greatly affected by the length of the spacers X, X’ between the silane functional group and the organic functional group. An example thereof is the “alpha” silane available from Wacker, where a methylene group is present between the Si atom and the functional group instead of the propylene group present in the case of the “gamma” silane.

[0165] In component e2), preferably, 10 to 80 mol%, preferably 15 to 70 mol%, more preferably 20 to 50 mol%, even more preferably 25 to 40 mol% of the originally present isocyanate groups react with at least one organosilane to preferably form structural unit (I) and / or (II), more preferably structural units (I) and (II).

[0166] Furthermore, component e2) is preferred in which the total amount of structural unit (I) is 3 to 90 mol%, more preferably 5 to 70 mol% based on the total of structural units (I)+(II) in each case, and the total amount of structural unit (II) is 97 to 10 mol%, more preferably 95 to 30 mol% based on the total of structural units (I)+(II) in each case.

[0167] At least one organic component e2) having on average two or more NCO groups functions as the parent structure of component 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, cycloaliphatic and / or heterocyclic di- and / or polyisocyanate, in particular an aliphatic and acyclic di- and / or polyisocyanate.

[0168] 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, where component 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, where component e2) has at least one structural unit of formula (I) and / or (II).

[0169] 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, where component e2) has at least one structural unit of formula (I) and / or (II). Trimers, i.e. isocyanurates, are particularly preferred.

[0170] The acyclic aliphatic polyisocyanate functioning as 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 aforementioned polyisocyanates.

[0171] More preferred polyisocyanate parent structures are polyisocyanates derived from such acyclic aliphatic 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 reaction of a polyol with a stoichiometric excess of the aforementioned 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 also mixtures of the aforementioned polyisocyanate parent structures. Particularly preferred polyisocyanate parent structures are hexamethylene diisocyanate and / or its isocyanurate trimer, optionally together with its uretdione.

[0172] The alicyclic polyisocyanate used as the parent structure is preferably a substituted or unsubstituted alicyclic polyisocyanate known per se. Examples of preferred polyisocyanates include 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'-methyldicyclohexyl diisocyanate (e.g., Desmodur® W from Bayer AG) and mixtures of the aforementioned polyisocyanates. Even more 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 be a polyisocyanate prepolymer having urethane structural units obtained by reaction of a polyol with a stoichiometric excess of the aforementioned 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 its biuret dimer and / or its allophanate dimer and / or its isocyanurate trimer.

[0173] Before incorporating e2) into component E), at least one silane used for reaction with at least one organic constituent e2) having on average two or more NCO groups is preferably at least one compound of formula (Ia), H - NR-(X - SiR’’ x (OR’) 3-x ) (Ia), and / or at least one compound of formula (IIa) HN(X-SiR’’ x (OR’) 3-x ) n (X’-SiR’’ y (OR’) 3-y ) m (IIa), wherein the substituents have the definitions as described above including the preferred definitions.

[0174] 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. Particularly preferred is N-(3-(trimethoxysilyl)propyl)butylamine. Amino silanes of these types are available, for example, under the trade names DYNASYLAN® from DEGUSSA or Silquest® from OSI.

[0175] 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, under the trade names DYNASYLAN® from DEGUSSA or Silquest® from OSI.

[0176] Optional component e3) The optionally present component e3) is an organic component having on average two or more NCO groups and is different from e2). In particular, the optionally present component e3) does not contain a silane-modified NCO group.

[0177] The optionally present component e3) may be the same as or different from component b2). Preferably, component e3) has on average two or more NCO groups.

[0178] Preferably, at least one organic component e3) optionally present in component E) 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 of IPDI (isophorone diisocyanate) and / or HDI (hexamethylene diisocyanate), i.e., isocyanurates, are particularly preferred.

[0179] 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 polyisocyanate. 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 also mixtures of the aforementioned polyisocyanate parent structures. Particularly preferred polyisocyanate parent structures are, optionally together with its uretdione, hexamethylene diisocyanate and / or its isocyanurate trimer.

[0180] 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, 4,4'-methyldicyclohexyl 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 the 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.

[0181] Optional 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 thus contains at least one organic solvent f1), preferably consisting of at least one organic solvent f1). Examples of such organic solvents include those already mentioned herein in connection with components a1), b1), c1), d1), and e1). Component F) may contain two or more 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 two or more organic solvents are used as a1), b1), c1), d1), e1), and / or f1), a1), b1), c1), d1), e1), and / or f1) may be partially the same and partially different.

[0182] Multilayer coating system A further subject of the invention is a multilayer coating system which is present on an optionally pre-coated substrate and can preferably be obtained by the method for preparing a multilayer coating system as described above, the multilayer coating system comprising at least three coating layers L1, L2, and L3 which are different from each other and are preferably arranged adjacent to each other, i.e., A first coating layer L1 which is applied on at least a part of the optionally pre-coated substrate, wherein the layer L1 can be obtained from the primer coating composition of the present invention, the first coating layer L1, A second coating layer L2 applied on the first coating layer L1, and A third coating layer L3 applied on the second coating layer L2, wherein the third coating layer L3 is preferably the outermost coating layer of the multilayer coating system, the third coating layer L3 comprising.

[0183] All preferred embodiments, and in each case preferred embodiments thereof, described herein above in relation to the primer coating system, the primer coating composition, the aforementioned methods and processes for use, and the coated substrates, and the methods for preparing the multi-layer coating system, are also preferred embodiments of such a multi-layer coating system.

[0184] Preferably, the multi-layer coating system is obtained by the method for preparing a multi-layer coating system described above.

[0185] method 1. Humidity exposure Humidity exposure is determined according to the high humidity test (96 hours) of GMW 14729 (4th edition, August 2020).

[0186] 2.Water vapor permeability The water vapor permeability is determined according to ASTM D1653(2021) test method A (dry cup method). The test was carried out at 38 °C and 90% RH (relative air humidity). The mass change was determined by the difference between the initial mass and the mass at different times during and after the test.

[0187] 3. Water intake Moisture uptake (water absorption) was determined by a mass change test. Mass change of the coated panel was determined by the difference between the initial mass of the coated panel and the mass of the coated panel after humidity exposure and storage at ambient conditions for 5 days and optionally for 6 months after exposure.

[0188] 4. Dynamic Light Scattering (DLS) The average particle size of component a3) (and of the silica starting material used) was determined by dynamic light scattering (DLS) according to the ISO 21501-4 standard. The measurements were carried out using a Beckman-Culter instrument (model: Delsa Nano C particle analyzer; software: Delsa Nano 2.31). Sample solutions were prepared at approximately 0.01% in filtered distilled water before checking.

[0189] 5. Non-volatile content The non-volatile content (solid fraction, solid content) is determined at 140 °C for 60 minutes in accordance with DIN EN ISO 3251:2018-07.

[0190] 6. Glass transition temperature The glass transition temperature is measured by DSC measurement in accordance with DIN EN ISO 11357-2 (2019-03).

Examples

[0191] 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".

[0192] 1. Preparation of a 2K primer coating system and the coating material composition obtained therefrom 1.1 The "A" components of the 2K primer coating system IPC1 (the present invention), the 2K primer coating system CPC1 (for comparison), and CPC2 (for comparison) were prepared by mixing the components shown in Table 1.1 in this order.

[0193]

Table 1

[0194] Pigment paste P1 contains 60% by mass of titanium dioxide pigment and further contains an alkyl resin. Pigment paste P2 contains 6% by mass of carbon black pigment and further contains an alkyl resin. Pigment paste P3 contains 10% by mass of organic blue pigment and further contains an alkyl resin. Pigment paste P4 contains 47% by mass of inorganic yellow pigment and further contains an alkyl resin. Nacure® 4167 is a commercially available amine-neutralized phosphate catalyst. TIB KAT® 216 is a liquid tin catalyst based on a dioctyltin compound. BYK 3565 is a commercially available surface-active additive. AS1 and AS2 are both commercially available aromatic solvent mixed solvents and are different from each other. NMP is N-methylpyrrolidone. CPO is a commercially available chlorinated polyolefin solution (solid content 19.8% by mass). ACL is a solvent-based chlorinated polypropylene modified with a commercially available acrylic resin, Acrydic® CL-408, which is OH-functional (solid content 44.0 - 46% by mass). The epoxy resin is a reaction product of bisphenol A and DGEBA, which is bisphenol A diglycidyl ether, and has an epoxy equivalent of 465 - 500.

[0195] 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 IPC1. 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) and LUDOX® AS-40 (24.5% by mass; 0.97 mol, of which 0.16 mol corresponds to silica and the remaining part also corresponds to the water present in this product) were added. Thus, the molar ratio of MTMS to silica was 0.45:0.16, i.e., approximately 2.8:1. Next, the resulting mixture was stirred at room temperature for 12 - 16 hours. Thereafter, acetic acid and TBAA (tetrabutylammonium acetate) as a catalyst were added (3.13% by mass of acetic acid and 0.17% by mass of TBAA), and the mixture was stirred for 2 - 3 hours while maintaining the pH at 5.1. Next, the resulting mixture (43% by mass solids) was diluted with isopropyl alcohol (mass ratio 1:1) and then used as the silica-silane condensate for preparing the "A" component of IPC1 in this form.

[0196] 1.2 The "B" component used in the 2K primer coating systems IPC1, CPC1 and CPC2 was prepared by mixing the components shown in Table 1.2 in this order.

[0197]

Table 2

[0198] Desmodur® N3600 is a commercially available aliphatic polyisocyanate (HDI trimer). Dynasylan® 1189 is N-(3-(trimethoxysilyl)propyl)butylamine. Dynasylan® 1124 is bis(trimethoxysilylpropyl)amine.

[0199] 1.3 The primer coating material compositions were each prepared by mixing the "A" and "B" components of primer coating systems IPC1, CPC1, and CPC2. For the preparation of the composition obtainable from IPC1, the "A" and "B" components were mixed with each other at a mass ratio of 14.4:1 ("A":"B"). For the preparation of the compositions obtainable from CPC1 and CPC2, the "A" and "B" components were mixed with each other at a mass ratio of 12.9:1 ("A":"B").

[0200] When applied onto the primer coating film obtainable from applying the primer coating material composition onto the surface of a substrate, the mixing ratio was calculated and selected such that the polyisocyanate derived from component "B" still existed in an excess amount of about 10 - 12% by mass in the resulting composition, in order to cure the subsequently applied base coat film via NCO migration.

[0201] 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 components shown in Table 2.1 in this order.

[0202]

Table 3

[0203] Catalyst 1 is a commercially available catalyst, namely TIB KAT (registered trademark) 216 (DOTL), a liquid tin catalyst based on dioctyltin compounds. Additive 1 is a commercially available liquid hydroxyphenyl - triazine (HPT) UV absorber. Additive 2 is a commercially available liquid hindered amine light stabilizer. Additive 3 is a commercially available silicone - containing surface additive. Additive 4 is a commercially available defoamer. Nacure (registered trademark) 4167 has already been described above in this specification. AS3 is a commercially available aromatic solvent mixture, different from AS1 and AS2 described above in this specification. Acrylic resin 1 is a solution of an OH - functional (meth)acrylic resin prepared from N - butyl methacrylate, styrene, 4 - hydroxybutyl acrylate, and 2 - hydroxyethyl acrylate, having a T of - 15°C (solid content: 65% by mass). g Acrylic resin 2 is a dispersion of an OH - functional (meth)acrylic resin prepared from 3 - hydroxypropyl methacrylate, 2 - ethylhexyl (meth)acrylate, and cyclohexyl (meth)acrylate, having a T of + 34°C g Acrylic resin 3 is a dispersion of an OH - functional (meth)acrylic resin prepared from n - butyl methacrylate, styrene, cyclohexyl methacrylate, 2 - hydroxypropyl methacrylate, and 2 - hydroxyethyl methacrylate, having a T of + 46°C g Acrylic resin 3 is a dispersion of an OH - functional (meth)acrylic resin prepared from n - butyl methacrylate, styrene, cyclohexyl methacrylate, 2 - hydroxypropyl methacrylate, and 2 - hydroxyethyl methacrylate, having a T of + 46°C (solid content: 60.0% by mass).

[0204] 2.2 The "B" component of the 2K clear coat system ICC1 is a polyisocyanate. A part of the NCO groups of the polyisocyanate (product Desmodur® N3600 was used as the starting material) was silanized by using two types of organosilanes (i.e., Dynasylan® 1189 and Dynasylan® 1124) before being used as the "B" component. Desmodur® N3600 is a commercially available aliphatic polyisocyanate (HDI trimer). Dynasylan® 1189 is N-(3-(trimethoxysilyl)propyl)butylamine. Dynasylan® 1124 is bis(trimethoxysilylpropyl)amine. The "B" component of ICC1 is commercially available (the "B" component of iGloss® refinish).

[0205] 2.3 The clear coat material composition was prepared by mixing the "A" component and the "B" component of the clear coat system ICC1 at a mass ratio of 1:1 ("A": "B") with each other.

[0206] 3. Properties of the primer coating film and the layer obtained from the primer coating material composition 3.1 Water vapor permeability By separately spraying the primer composition IPC1 or CPC1 onto a Tedlar® film using a p-Mac spray applicator, self-supporting primer coating films were obtained. After a 10-minute room temperature flash-off, both films were baked in an oven at 50 °C for 30 minutes to obtain dry films with a thickness of 0.5 mil (12.7 μm). Then, using a sharp knife, the self-supporting primer coating films were carefully removed from the Tedlar® film.

[0207] In accordance with the method disclosed in this specification, the water vapor permeability of the self-standing primer film was measured. The results are shown in Figure 1. This graph shows the water vapor permeability of a self-standing control primer film (a primer film obtained from the composition obtained from the comparative primer coating system CPC1) with respect to the primer film of the present invention (a primer film obtained from the composition obtained from the primer coating system IPC1 of the present invention) containing about 9% by mass of silica-silane condensate, based on the total mass of the primer composition IPC1 before application. As shown in Figure 1, a significant difference in water vapor permeability was observed: the film obtained from IPC1 had about 35% lower permeability than the control film obtained from CPC1. Therefore, without the silica-silane condensate, a lower water vapor barrier property is observed.

[0208] The data shown in Figure 1 are summarized in Table 3.1a and Table 3.1b.

[0209] [Table 4]

[0210] [Table 5]

[0211] 3.2 Moisture Absorption after Humidity Exposure and Storage The product Ultramid® XA3418, which is 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 the primer coating system IPC1 or CPC1 or CPC2 prepared as described in Item 1.3 was applied to the surface of the substrate to form a primer film, and it was flash-dried for 10 minutes under ambient conditions (room temperature). Subsequently, a commercially available pigmented solvent-based basecoat material composition (Hot Pepper Red) was sprayed onto the primer film to form a basecoat film, and it was flash-dried for 10 minutes under ambient conditions (room temperature). Then, the clearcoat material composition obtained from the clearcoat system ICC1 prepared as described in Item 2.3 was applied onto the basecoat film, flash-dried for 10 minutes under ambient conditions (room temperature), and then all the films were simultaneously baked at a substrate temperature of 122°F (50°C) for 30 minutes. The dry film thickness of each primer layer obtained after curing from each primer film was in the range of 0.5 to 1 mil (12.7 μm to 25.4 μm). The dry film thickness of each basecoat layer obtained after curing from each basecoat film was in the range of 0.6 to 1 mil (15.24 μm to 25.4 μm), and the dry film thickness of each clearcoat layer obtained after curing from each clearcoat film was in the range of 1.9 to 2.1 mil (48.26 μm to 53.34 μm).

[0212] Water uptake was measured according to the method disclosed herein. The effect of humidity on the coated PA-CF (carbon fiber reinforced polyamide) substrate was investigated by exposing the coated samples (PA-CF substrates) coated with all three layers (i.e., primer / base coat / clear coat) to a humidity chamber according to the test method described in the "Method" section. The water uptake was measured 5 days and 6 months after the humidity test was carried out (during which the coated substrates were stored at room temperature and ambient conditions). All coated substrates had similar coating layers except for the primer prepared using the primer coating system IPC1 or CPC1 or CPC2. Water absorption was investigated by measuring the mass increase after exposure and storage: the mass change of the coated panel was determined by the difference between the mass of the initial coated panel and the mass after humidity exposure (after 5 days of equilibrium and after 6 months).

[0213] As shown in Table 3.2, the water (moisture) absorption observed in the substrates coated with the multi-coat containing the primer film of the present invention (the primer film obtained from the composition obtained from the primer coating system IPC1 of the present invention) was significantly less (about 38 - 40 mass%) compared to the substrates coated with the multi-coat containing the control primer (the primer film obtained from the composition obtained from the comparative primer coating systems CPC1 or CPC2). In Table 3.2, panels not coated were also investigated as control substrates.

[0214]

Table 6

Claims

1. A primer coating system comprising at least two components A) and B), which are different from each other and separate from each other, and optionally at least one further component C), wherein component A) comprises at least constituents a2) and a3), which are different from each other, and optionally at least one constituent a1), i.e., optionally at least one organic solvent a1), at least one polymer a2) containing a functional group reactive with an NCO group, and at least one condensation product a3) obtainable at least by the reaction of (i) at least one organosilane having at least one hydrolyzable group and (ii) at least one silica, wherein the molar ratio of at least one organosilane to at least one silica used is in the range of 10:1 to 1:1, at least one condensation product a3) is included, component B) comprises at least constituents b2), which are different from each other, and optionally at least one constituent b1), i.e., optionally at least one organic solvent b1), and at least one organic component b2) having on average two or more NCO groups is included, and any component C) is a reducing agent component and comprises at least one organic solvent c1), a primer coating system.

2. In each case, based on the total mass of component A), at least one condensation product a3) is present in component A) in an amount in the range 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, even 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. The primer coating system according to claim 1.

3. In each case, the condensation product a3) has an average particle size in the range of 10 to 100 nm, preferably 15 to 80 nm, more preferably 20 to 70 nm, even more preferably 25 to 60 nm, even more preferably 30 to 50 nm, and most preferably 35 to 45 nm, as measured by DLS (dynamic light scattering). The primer coating system according to claim 1 or 2.

4. The molar ratio of at least one organosilane to at least one silica used in the preparation of the condensation product a3) is in the range of 8:1 to 1:1, preferably 6:1 to 1:1, more preferably 4:1 to 1:1, even more preferably 4:1 to 1.1:1, even more preferably 4:1 to 1.5:1, and most preferably 4:1 to 2:

1. The primer coating system according to claim 1 or 2.

5. The condensation reaction of at least one organosilane having at least one hydrolyzable group and at least one silica is carried out in an aqueous medium, preferably catalyzed by at least one preferably organic acid. The primer coating system according to claim 1 or 2.

6. Component A) further contains at least one catalyst a4) suitable for crosslinking Si-containing functional groups, especially the Si-containing functional groups present in the condensation product a3) of component A), and / or preferably at least one catalyst a5) suitable for crosslinking the NCO groups of the constituent component b2) of component B). The at least one catalyst a4) is different from any of the constituent components a1) to a3). In each case, based on the total mass of component A), it is preferably in the range of 0.01 to 2.5% 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 even more preferably 0.05 to 1.0% by mass. The catalyst a4) is preferably selected from phosphorus-containing organic components, more preferably acyclic phosphoric acid diesters, acyclic phosphoric acid monoesters, cyclic phosphoric acid diesters, and cyclic phosphoric acid monoesters. Each of the aforementioned phosphoric acid diesters and monoesters can optionally exist in the form of an adduct with at least one amine, preferably at least one tertiary amine. Even more preferably, at least two catalysts exist as at least one catalyst a4), and both of them are selected from acyclic phosphoric acid diesters, acyclic phosphoric acid monoesters, cyclic phosphoric acid diesters, and cyclic phosphoric acid monoesters. At least one of these at least two catalysts exists in the form of its amine adduct, and the other one of these at least two catalysts does not exist as an amine adduct. The at least one catalyst a5) is different from any of the constituents a1) to a3) and also from catalyst a4), and in each case is present in an amount of from 0.001 to 1.00% by weight, more preferably from 0.002 to 0.80% by weight, even more preferably from 0.003 to 0.60% by weight, even more preferably from 0.004 to 0.40% by weight, even more preferably from 0.005 to 0.20% by weight, most preferably from 0.007 to 0.15% by weight, based on the total mass of component A). Preferably, catalyst a5) is selected from organotin catalysts. The primer coating system according to claim 1 or 2.

7. At least one organic constituent b2) present in component B) has an aliphatic or cycloaliphatic structure and / or a parent structure derived from an aliphatic or cycloaliphatic polyisocyanate by trimerization, dimerization, urethane formation, biuret formation, uretdione formation and / or allophanate formation, and / or Component B) further comprises at least one organosilane component b3) which is different from each of constituents b1) and b2) and has at least one hydrolyzable group and preferably further at least one non-hydrolyzable organic residue. The primer coating system according to claim 1 or 2.

8. Component A) is different from one another and different from each of constituents a1) to a3), and different from each of constituents a4) and a5) as defined in claim 6, the following constituents a6) to a8), namely As constituent a6), in each case in an amount in the range of preferably from 0.5 to 15.0% by weight, more preferably from 1.0 to 10.0% by weight, even more preferably from 1.5 to 7.5% by weight, still more preferably from 2.0 to 5.5% by weight, based on the total mass of component A), of at least one epoxy resin, As constituent a7), in each case in an amount in the range of preferably from 5.0 to 35% by weight, more preferably from 6.0 to 30.0% by weight, even more preferably from 7.0 to 25.0% by weight, still more preferably from 8.0 to 20% by weight, based on the total mass of component A), of at least one chlorinated polyolefin, and As component a8), in each case, based on the total mass of component A), 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, still more preferably 8.0 to 15% by mass, at least one pigment and / or filler The primer coating system according to claim 1 or 2, comprising at least one, preferably at least two, more preferably at least three of them.

9. Component A) contains at least one leveling agent and / or dispersant as additive component a9), and component a9) is preferably a (meth)acrylate polymer, preferably contains at least one ether segment(s), more preferably in the side chain, and / or preferably contains at least one siloxane unit, more preferably also in the side chain. Component a9) is present in component A) in the range of preferably 0.10 to 5.0% by mass, more preferably 0.50 to 4.0% by mass, even more preferably 0.80 to 3.5% by mass, in each case based on the total mass of component A). The primer coating system according to claim 1 or 2.

10. A primer coating composition, which can be obtained by mixing at least components A) and B) of the primer coating system according to claim 1 or 2, and optionally C) with each other, or at least components (i), (ii) and (iii), and optionally (iv), which are different from each other, i.e., (i) optionally at least one organic solvent corresponding to at least one of the organic solvents a), b1) and / or c1) preferably defined in claim 1, (ii) at least one film-forming polymer corresponding to at least one polymer a2) which is self-crosslinkable or externally crosslinkable, preferably externally crosslinkable, more preferably containing a functional group reactive with respect to the NCO group as defined in claim 1, (iii) at least one condensation product corresponding to the condensation product a3) defined in claim 1 or 2, and (iv) optionally, when at least one film-forming polymer (ii) is an externally crosslinkable polymer, at least one crosslinking agent preferably selected from blocked polyisocyanates, melamine formaldehyde resins and mixtures thereof. A primer coating composition comprising

11. When applying to an intermediate coating film, preferably a base coat film, applied on a primer coating film obtained from the primer coating composition on a substrate, and at least partial curing of the intermediate coating film is achieved during the transfer of the constituent components, an excess of constituent component b2) having on average two or more NCO groups is included, and the intermediate coating film contains at least one preferably polymeric constituent component containing a functional group reactive with an NCO group. The primer coating composition according to claim 10.

12. A method of use for improving the water resistance and / or moisture resistance of a cured primer coating film obtainable from the primer coating composition according to claim 10 and / or a cured multilayer coating system comprising at least one cured primer coating film, wherein the cured primer coating film is obtainable from the primer coating composition.

13. At least step 1), that is 1) Applying at least partially the primer coating composition according to claim 10 to at least one surface of an optionally pre-coated substrate to form a primer coating film on the surface, and 1a) Optionally, at least one further step 1a) of curing at least one primer coating film obtained after step 1) to obtain at least one cured primer coating layer on the surface A method of coating a substrate comprising

14. A coated substrate obtainable by the method according to claim 13.

15. At least steps 1) to 3) and optionally 4), that is 1) A step of applying at least partially a first coating composition to at least one surface of an optionally pre-coated substrate to form a first coating film on the surface, wherein the first coating composition is the primer coating composition according to claim 10. 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, and preferably forming a second coating film adjacent to the first coating film; 3) Applying a top coat composition, preferably a clear coat composition, as a third coating composition onto the second coating film present on the substrate obtained after step 2), preferably before curing the second coating film, and preferably forming a third coating film which is adjacent to the second coating film and is preferably the outermost coating film of the multilayer coating system to be formed; 4) Optionally, co-curing the first, second, and third coating films to obtain a multilayer coating system comprising cured first, second, and third coating layers; A method for preparing a multilayer coating system on at least one surface of an optionally pre-coated substrate, comprising the steps above.

16. A multilayer coating system present on at least one surface of an optionally pre-coated substrate, preferably obtainable by the method according to claim 15, comprising at least three coating layers L1, L2, and L3 which are different from each other and are preferably arranged adjacent to each other, i.e., A first coating layer L1 applied onto at least a part of the optionally pre-coated substrate, wherein the layer L1 can be obtained from the primer coating composition according to claim 10; A second coating layer L2 applied onto the first coating layer L1; and A third coating layer L3 applied onto the second coating layer L2, wherein the third coating layer L3 is preferably the outermost coating layer of the multilayer coating system; A multilayer coating system comprising the above.

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