Primer coating systems and compositions for achieving excellent water resistance

Abstract

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

Description

[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 one another or a 1K primer coating composition itself, the use of 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 such a cured film, a method for coating a substrate using the primer coating composition, a method for preparing a multilayer coating system using the primer coating composition so as 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 a layer obtained from the primer coating film. Background Art

[0002] In a typical automotive coating process, multiple layers are usually applied to the surface of a suitable substrate in the form of a multilayer coating system. Specifically, in the case of using a plastic or fiber-reinforced plastic substrate, at least a primer, at least one base coat and a top coat, particularly a clear coat as the outermost layer, are applied in this order. At least the base coat and the top coat are usually applied using wet-on-wet application today. Afterwards, the coated substrate is passed through an oven at a temperature where at least the base coat and the top coat, such as a clear coat, are simultaneously cured with, for example, a 2C1B process. In some cases, the primer coating is also cured with, for example, a 3C1B process at this stage together with the base coat and the top coat, particularly the clear coat.

[0003] There are considerable necessary requirements which, due to regulations but also due to the quality standards set by the automotive industry, must be achieved and / or satisfied by the individual layers present in the multilayer coatings used in the automotive industry and by the multilayer coatings themselves. Therefore, the multilayer coatings must exhibit or display a number of desirable characteristics to at least a sufficient degree in order to meet these requirements.

[0004] For example, it is desirable to avoid any failure of the film or layer caused by moisture penetration through the coating film of the multilayer coating to the substrate due to exposure to external adverse weather conditions. Therefore, it is desirable to achieve excellent water vapor barrier properties in order to avoid any swelling of the substrate used (especially polar substrates), and to maintain a durable appearance combined with good adhesion properties (especially between primer and substrate). For the exterior body parts of automobiles, providing such durable coatings with good adhesion properties has become one of the key requirements for maintaining the life of painted automobile body parts. In the case of plastic substrates including reinforced plastic substrates, durable coatings are necessary so that these can be used as substitutes for metal parts. Especially for polar substrates, it is challenging to maintain a durable coating on the substrate due to the tendency to absorb moisture from the air under ambient conditions.

[0005] Conventional automotive coating systems often exhibit only poor water vapor barrier properties, which lead to defects, in particular cosmetic defects, in the painted parts after a certain period of time.

[0006] Therefore, there is a need to provide new coating films and multilayer coating systems on substrates, in particular on plastic substrates including reinforced plastic substrates, which have no or at least less moisture permeability than observed for conventional coating films and multilayer coating systems, i.e., they exhibit excellent water vapor barrier properties (water resistance) and thus allow durable coating films and multilayer coating systems to maintain an excellent appearance even after a long period of time.

[0007] question

[0008] It is therefore an underlying object of the present invention to provide coating films and multilayer coating systems on substrates, in particular on plastic substrates including reinforced plastic substrates, which have no or at least less moisture permeability than is observed for conventional coating films and multilayer coating systems, and thus exhibit excellent water vapor barrier properties and, in particular, allow durable coating films and multilayer coating systems to maintain an excellent appearance even after a long period of time due to these improved barrier properties.

[0009] plan

[0010] This object has been solved by the subject matter of the claims of the present application and by its preferred embodiments disclosed in the present description, ie by the subject matter described herein.

[0011] A first subject of the present invention is a primer coating system comprising at least two components A) and B) and optionally at least one further component C), which are different from one another and are separated from one another,

[0012] The component A) comprises at least components a2) and a3) and optionally at least one component a1), which are different from one another, namely

[0013] optionally at least one organic solvent a1),

[0014] at least one polymer a2) which contains functional groups reactive toward NCO groups, which is preferably at least one OH-functional polymer, and

[0015] at least one condensation product a3) obtainable at least by reaction of (i) at least one organosilane carrying at least one hydrolyzable group with (ii) at least one silicon dioxide, wherein the at least one organosilane and the at least one silicon dioxide are preferably used in a molar ratio to one another in the range from 10:1 to 1:1,

[0016] The component B) comprises at least two components b2) and optionally at least one component b1), which are different from each other, namely

[0017] optionally at least one organic solvent b1), and

[0018] at least one organic component b2) which carries on average two or more NCO groups, and

[0019] The optional component C) is a reducing agent component and comprises at least one organic solvent c1).

[0020] Another subject of the invention is a primer coating composition,

[0021] It is obtainable by mixing at least components A) and B) and optionally C) of the primer coating system of the invention with one another.

[0022] or

[0023] It comprises at least components (i), (ii) and (iii) and optionally also (iv), which are different from each other, namely

[0024] (i) at least one organic solvent, which preferably corresponds to at least one organic solvent a), b1) and / or c1) as defined for the primer coating system of the invention,

[0025] (ii) at least one film-forming polymer which is self-crosslinking or externally crosslinking, preferably externally crosslinking, more preferably which corresponds to the at least one polymer a2) containing functional groups reactive toward NCO groups as defined for the primer coating system of the invention,

[0026] (iii) at least one condensation product corresponding to the condensation product a3) as defined for the primer coating system of the invention, and

[0027] (iv) at least in case the at least one film-forming polymer (ii) is an externally crosslinked polymer, optionally at least one crosslinking agent, preferably selected from blocked polyisocyanates, melamine formaldehyde resins and mixtures thereof.

[0028] Another subject of the present invention is the use of 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, the cured primer coating film being obtainable from the primer coating composition.

[0029] Another subject of the present invention is a method for coating a substrate, comprising at least step 1) and optionally also step 1a), namely

[0030] 1) applying the primer coating composition at least partially to at least one surface of an optionally pre-coated substrate and forming a primer coating film on the surface,

[0031] 1a) and optionally at least one further step 1a): curing the at least one primer coating film obtained after step 1) to obtain at least one cured primer coating on said surface.

[0032] Another subject of the present invention is a coated substrate obtainable by the process.

[0033] Another subject of the present invention is a method for producing a multilayer coating system on at least one surface of an optionally precoated substrate, the method comprising at least steps 1) to 3) and optionally 4), namely

[0034] 1) applying a first coating composition at least partially to at least one surface of an optionally pre-coated substrate and forming a first coating film on said surface, wherein the first coating composition is said primer coating composition,

[0035] 2) applying at least one base coating 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 forming a second coating film preferably adjacent to the first coating film, and

[0036] 3) applying a top coating composition, preferably a clear coating 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 forming a third coating film, which is preferably adjacent to the second coating film and is preferably the outermost coating film of the formed multi-layer coating system, and

[0037] 4) optionally co-curing the first, second and third coating films to obtain a multi-layer coating system comprising cured first, second and third coatings.

[0038] Another subject of the present invention is a multilayer coating system present on an optionally precoated substrate, preferably obtainable by the process for producing a multilayer coating system, and comprising at least three coating layers L1, L2 and L3 which are different from one another and are preferably positioned adjacent to one another, namely

[0039] a first coating L1 applied on at least a portion of the optionally precoated substrate, said layer L1 being obtainable from a primer coating composition according to the invention,

[0040] a second coating L2 applied on the first coating L1, and

[0041] A third coating L3 is applied on the second coating L2, wherein the third coating L3 is preferably the outermost coating of the multi-layer coating system.

[0042] It has been found, particularly surprisingly, that the water permeability of a self-supporting cured primer film obtained from a primer coating composition according to the invention, which in turn is obtained from a primer coating system according to the invention, can be significantly reduced due to the presence of condensation products a3) in component A) of the primer coating system. Figure 1 As shown, a significant difference in water vapor permeability is observed: the film obtained from the primer coating composition of the invention comprising component a3) has a permeability of about 35% lower than the control film obtained from the primer coating composition not comprising any component a3). Thus, in the absence of component a3), poorer moisture barrier properties are observed.

[0043] Furthermore, it has been found, particularly surprisingly, that for substrates coated with a multilayer coating system comprising a primer layer derived from a primer film, obtained from a primer coating composition which in turn is obtained from a primer coating system according to the invention comprising component a3) in its component A), in particular plastic substrates, such as carbon fiber reinforced plastic substrates including carbon fiber reinforced polyamide, significantly less moisture absorption (water absorption) after humidity exposure and storage (about 40 wt. % less) is observed compared to substrates coated with the same multilayer coating system but containing a control primer film instead of the primer coating film according to the invention, which control primer film does not contain any component a3). Furthermore, it has been found, further surprisingly, that this effect can be observed for a wide variety of different kinds of substrates and also independently of the nature of the primer material (solvent-borne and water-based primer) used as an intermediate coating for the production of the multilayer coating system.

[0044] In particular, it has been further surprisingly found that in the case of carbon fiber reinforced polyamide (PA-CF) substrates with a multilayer coating system, when conventional primers are used, the appearance is dynamic, in particular the appearance becomes worse over time under ambient conditions, which is probably due to the highly polar nature of the polyamide substrate, which swells by absorbing moisture from the air under ambient conditions. When using the primer film of the invention comprising component a3), this undesirable effect is not observed.

[0045] Furthermore, it has been found that the primer coating composition of the present invention can be cured at low temperatures as low as 50° C., which is energy efficient and eco-friendly and is particularly advantageous when the substrate used is a plastic substrate.

[0046] It has also been found that 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 primer coating film applied on top of the primer coating film even at temperatures as low as 50° C. due to the migration of isocyanates from the primer coating film into the primer coating film, especially when the primer coating composition used contains an excess of component b2) having an average of two or more NCO groups, so that when the component migrates into the above-mentioned primer coating film applied on top of the primer coating film obtained from the primer coating composition, at least partial curing of the primer coating film is achieved when the film contains at least one preferably polymeric component (which contains functional groups reactive with the NCO groups of component b2)). DETAILED DESCRIPTION

[0047] In the sense of the present invention, the term "comprising", for example in relation to one of the components of a primer coating composition or a primer coating system, preferably has the meaning of "consisting of". For example, with respect to one of the components of a primer coating composition or a primer coating system, in addition to all mandatory ingredients present therein, one or more further optional ingredients as defined below may also be included therein. In each case, all ingredients may be present in their preferred embodiments, as defined below.

[0048] The proportions and amounts of any ingredients given below in wt.-% (weight %) present in each coating composition, such as the primer coating composition, add up to 100 wt.-%, in each case based on the total weight of the coating composition. The same applies to each component of the coating system, such as component A) or B) of the primer coating system: the proportions and amounts of any ingredients given below in wt.-% (weight %) present in one of these components add up to 100 wt.-%, in each case based on the total weight of the respective component.

[0049] Primer coating system

[0050] As outlined above, the primer coating system comprises at least two components A) and B) and optionally at least one additional component C), which are different from each other and separated from each other, i.e., a two-(2K-) or multi-component coating system. In this context, separated from each other means that the components A) and B) and optionally C) of the coating system can be stored separately until they are mixed with each other in order to prepare the primer coating composition. In the case where the coating system is a two-component coating system, it preferably consists of components A) and B). When mixing at least two components A) and B) and applying the resulting composition to the surface of the substrate, a polyurethane or polyurethane-based coating film is preferably formed at least by the reaction of the OH-groups of at least one component a2) with the isocyanate groups of at least one component b2).

[0051] Preferably, components A) and B) and optionally also component C) of the coating system contain no or essentially no water. The same applies to the coating compositions obtainable therefrom. In the sense of the present invention, the term "free of water" preferably means that no water is present at all. In the sense of the present invention, the term "essentially free of water" preferably means that essentially no water is present. This means that at least no water is intentionally added to any of the components A) and B) and optionally C) used in the present invention and to the coating compositions obtainable therefrom. However, it cannot be excluded that residual residues of water formed during the preparation of any of the ingredients used to prepare the 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) and B) and optionally C) is less than 1 wt.-%, more preferably less than 0.5 wt.-%, even more preferably less than 0.1 wt.-%, still more preferably less than 0.05 wt.-%, yet more preferably less than 0.01 wt.-%, in particular less than 0.005 wt.-% or less than 0.001 wt.-%, in each case based on the total weight of components A) or B) or optionally C). Preferably, components A) and B) and also optional component C) of the coating system are solvent-borne, i.e. based on organic solvents. Thus, preferably, the coating system is not water-based, i.e. not an aqueous coating system.

[0052] Component A)

[0053] Component A) comprises at least the ingredients a2) and a3) and optionally a1), which are different from one another, but may additionally comprise further optional ingredients.

[0054] Preferably, component A) of the primer coating system has a total solids content of >20 wt.-%, preferably >25 wt.-%, more preferably >30 wt.-%, based on the total weight of component (A). The total solids content of component A) of the primer coating system is preferably in the range of >20 to 60 wt.-%, more preferably 25 to 50 wt.-%, even more preferably 30 to 45 wt.-%, in each case based on the total weight of component A). The total solids content, in other words the non-volatile fraction, is determined according to the method described below.

[0055] Optional ingredient a1)

[0056] Optional component a1) is at least one organic solvent. Examples of such organic solvents include heterocyclic, aliphatic or aromatic hydrocarbons, monohydric or polyhydric alcohols, in particular methanol and / or ethanol, ethers, esters, ketones and amides, for example N-methylpyrrolidone, N-ethylpyrrolidone, dimethylformamide, toluene, xylene, butanol, ethylene glycol and butanediol and also their acetates, butyl diglycol, diethylene glycol dimethyl ether, cyclohexanone, methyl ethyl ketone, methyl isobutyl ketone, acetone, isophorone, or mixtures thereof. Component A) may contain more than one organic solvent a1).

[0057] Preferably, the amount of ingredient a1) in component (A) is in the range from 10 to 80 wt.-%, more preferably 25 to 75 wt.-%, even more preferably 40 to 70 wt.-%, in each case based on the total weight of component A).

[0058] Ingredient a2)

[0059] Component a2) is at least one polymer, it contains functional groups such as OH-groups, thiol groups, carbamate groups, COOH-groups and / or amino groups that are reactive to NCO-groups. Preferably, component a2) is an OH-functional polymer. Component a2) such as OH-functional polymers preferably act as film-forming adhesives. For the purposes of the present invention, the term "adhesive" is understood as a non-volatile component of the coating composition according to DINEN ISO 4618 (German version, date: March 2007), which is responsible for film formation. Therefore, the pigment and / or filler contained therein are not included under the term "adhesive". Preferably, component a2) represents the main adhesive. As the main adhesive in the sense of the present invention, the adhesive component is preferably mentioned, when there are no other adhesive components in the coating composition or the components used for its preparation, the adhesive component is present in a higher proportion based on the total weight of the coating composition or the components.

[0060] The term "polymer" is known to the person skilled in the art and for the purposes of the present invention encompasses addition polymers and polymerizates as well as condensation polymers. The term "polymer" includes both homopolymers and copolymers.

[0061] If component a2) is at least one OH-functional polymer, it preferably contains on average two or more OH groups.

[0062] Any type of polymer having functional groups reactive toward NCO groups can be used as component a2). Examples are (meth)acrylic polymers, polyesters, polyurethanes, polyureas and polyethers and mixtures thereof.

[0063] Preferably, component a2) is at least one OH-functional (meth)acrylic polymer, more preferably at least one OH-functional (meth)acrylic polymer, which has been modified with at least one chlorinated polyolefin. Examples of such polymers are CL-408.

[0064] Preferably, component A) of the primer coating system comprises at least one ingredient a2) in an amount in the range from 5.0 to 50.0 wt.-%, more preferably from 10.0 to 45.0 wt.-%, even more preferably from 15.0 to 40.0 wt.-%, yet more preferably from 17.5 to 35.0 wt.-%, in each case based on the total weight of component A).

[0065] Ingredient a3)

[0066] Component a3) is at least one condensation product which is obtainable at least by the reaction of (i) at least one organosilane with at least one hydrolyzable group with (ii) at least one silicon dioxide. The condensation product a3) is also referred to herein as a "condensate". It has been found that the condensation product a3) leads to excellent water vapor barrier properties of the cured coating film derived from the primer coating composition which is in turn obtainable by mixing components A) and B) and optionally C) with one another.

[0067] Preferably, the molar ratio of the at least one organosilane and the at least one silicon dioxide used to prepare the condensation product a3) to one another is in the range from 10:1 to 1:1, more preferably from 8:1 to 1:1, even more preferably from 6:1 to 1:1, yet more preferably from 4:1 to 1:1, still more preferably from 4:1 to 1.1:1, yet more preferably from 4:1 to 1.5:1, most preferably from 4:1 to 2:1.

[0068] Preferably, the at least one condensation product a3) is present in component A) in an amount within the range of 1.0 to 25.0 wt.-%, more preferably 2.0 to 20.0 wt.-%, even more preferably 3.0 to 17.5 wt.-%, yet more preferably 4.0 to 15.0 wt.-%, still more preferably 5.0 to 14.0 wt.-%, even more preferably 6.0 to 13.0 wt.-%, most preferably 7.0 to 12.0 wt.-%, in each case based on the total weight of component A).

[0069] 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, yet more preferably 25 to 60 nm, still more preferably 30 to 50, most preferably 35 to 45 nm, in each case measured by DLS (dynamic light scattering). The DLS method used is described below in the 'Methods' section. Preferably, the average particle size is measured at a high shear viscosity of 5 to 15 cP measured by using a CAP 2000 viscometer.

[0070] The term "silicon dioxide" used in this context is a term that is clear to the person skilled in the art and refers to SiO2. Preferably, the at least one silicon dioxide used is used in the form of an alkaline or acidic, preferably alkaline aqueous dispersion of preferably colloidal silicon dioxide particles. Preferably, the silicon dioxide particles have an average particle size of silicon dioxide 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, most preferably 10 to 30 nm. The average particle size is measured by DLS. The DLS method used is described below in the 'Methods' section and is the same method that is also used to determine the average particle size of the condensation product a3).

[0071] As outlined above, both acidic and basic colloidal silica dispersions may be used. However, colloidal silica dispersions having a low base content are preferred.

[0072] Commercially available silica products that can be used include, for example (Sigma Aldrich), (Nissan Chemical), (AkzoNobel), Colloidal silica (Nalco Chemical Company) and (Akzo Nobel) products. Particularly preferred colloidal silicon dioxide products that can be used include 1034A(Nalco Chemical Company), O40, Snowtex ST-033 and OL-40 (Nissan Chemical Co., Ltd.), AS40 and HS 40 (Sigma-Aldrich), Levasil 200 / 30 and 200 S / 30 (now Levasil CS30-516P) (Akzo Nobel) and Cab- A205 (Cabot Corporation), etc.

[0073] The at least one organosilane carrying at least one hydrolyzable group may optionally comprise and preferably comprises at least one non-hydrolyzable group, which is preferably an organic (preferably aliphatic) residue having 1 to 10 carbon atoms, optionally further comprising at least one functional group.

[0074] Preferably, the at least one organosilane carrying at least one hydrolyzable group is a monosilane and has at least two, particularly preferably at least three, hydrolyzable groups X, and / or is at least one bis(silane) which preferably has at least four, particularly preferably six, hydrolyzable groups X. However, it is also possible to use monosilanes having four hydrolyzable groups X, i.e. monosilanes which do not contain any non-hydrolyzable residues, such as tetramethoxysilane and / or tetraethoxysilane.

[0075] Preferably, the at least one organosilane having at least one hydrolyzable group is an organosilane having the general formula (1) and / or (2):

[0076] Si(X) 4-y (R) y ,

[0077] (1)

[0078] Si(X) 3-z (T) z -(RA)-Si(X) 3-z (T) z

[0079] (2)

[0080] In the case of general formula (1)

[0081] X is each independently a hydrolyzable group, preferably each independently selected from OC 1-4 alkyl,

[0082] The parameter y is 0 or an integer in the range of 1 to 3, preferably at least 1, preferably exactly 1, and

[0083] R is a non-hydrolyzable organic residue, preferably an aliphatic residue, which preferably has 1 to 10 carbon atoms, wherein at least one of the residues R optionally contains at least one functional group,

[0084] And in the case of general formula (2)

[0085] X represents in each case independently of one another a hydrolyzable group and is preferably in each case independently of one another selected from OC 1-4 -alkyl,

[0086] RA represents a divalent non-hydrolyzable organic residue, preferably an aliphatic residue, which preferably has 1 to 10 carbon atoms and which preferably contains no functional groups,

[0087] The parameter z is in each case 0 or an integer in the range from 1 to 3, preferably in each case 0 or 1, more preferably in each case 1, and

[0088] T is a non-hydrolyzable organic residue, preferably an aliphatic residue, which preferably has 1 to 10 carbon atoms, which is different from the residue RA, and which optionally comprises at least one functional group.

[0089] Examples of suitable functional groups are in particular thiol groups, amino groups, epoxy groups, in particular glycidyloxy, epoxycyclohexyl and / or epoxycyclohexylethyl groups, OH groups protected by suitable protective groups, (meth)acrylate groups, vinyl groups, allyl groups, (meth)acryloyloxy groups, episulfide groups, urea groups, thiourea 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 R3 is an aliphatic residue which preferably has 1 to 10 carbon atoms.

[0090] Examples of suitable organosilanes bearing at least one non-hydrolyzable group are, for example, (3-aminopropyl)trimethoxysilane, (3-aminopropyl)triethoxysilane, N-2-aminoethyl-3-aminopropyltrimethoxysilane, (3-mercaptopropyl)trimethoxysilane, (3-mercaptopropyl)triethoxysilane, (3-glycidyloxypropyl)trimethoxysilane, (3-glycidyloxypropyl)triethoxysilane, bis(2-ethyl)- triethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, propyltrimethoxysilane, and / or propyltriethoxysilane.

[0091] Preferably, the condensation reaction of at least one organosilane carrying at least one hydrolyzable group with at least one silicon dioxide takes place in an aqueous medium and is preferably catalyzed by at least one preferably organic acid.

[0092] Preferably, at least one silica is added to at least one organosilane in the presence of water, preferably 0.5-2.0 moles of water, based on the molar amount of at least one organosilane, and in the presence of preferably catalytic amounts of at least one acid, more preferably at least one organic acid such as acetic acid. The addition is preferably carried out at a temperature between 0°C and 10°C. After stirring the resulting mixture, preferably at room temperature (18°C to 23°C) for 10 to 18 hours, preferably a further catalytic amount of at least one acid, more preferably at least one organic acid such as acetic acid and at least one ammonium salt such as tetrabutylammonium acetate (TBAA) is added as a further catalyst. Then, the resulting mixture is preferably stirred for 1 to 10 hours. Preferably, the pH value of the mixture is maintained at pH 3 to 6. Then, the resulting mixture is preferably diluted with at least one water-miscible organic solvent such as isopropanol (IPA), for example in a 1:1 weight ratio.

[0093] The preparation of exemplary condensation products a3) prepared from methyltrimethoxysilane (MTMS) as organosilane is Figure 2 Overview.

[0094] Components a4) and a5)

[0095] Preferably, component A) of the primer coating system further comprises at least one catalyst a4) which is suitable for crosslinking Si-containing functional groups, the catalyst a4) being different from each of the components a1) to a3).

[0096] Preferably, the at least one catalyst a4) is suitable for crosslinking Si-containing functional groups present in constituent b3) of component B), if constituent b3) is present.

[0097] Preferably, component A) of the primer coating system comprises at least one catalyst a4) in an amount in the range from 0.01 to 2.5 wt.-%, more preferably from 0.02 to 2.0 wt.-%, even more preferably from 0.03 to 1.5 wt.-%, still more preferably from 0.04 to 1.2 wt.-%, yet more preferably from 0.05 to 1.0 wt.-%, in each case based on the total weight of component A).

[0098] Preferably, at least one catalyst a4) is a phosphorus-containing catalyst and / or a phosphorus-containing and nitrogen-containing catalyst. It is possible to use more than one, for example two different catalysts as catalyst a4).

[0099] 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. More particularly, however, substituted phosphoric acid monoesters and diesters, preferably selected from the group consisting of acyclic phosphoric acid diesters and monoesters and cyclic phosphoric acid diesters and monoesters, which in each case may be amine adducts, for example amine adducts of phosphoric acid monoesters and diesters, are used as at least one catalyst a4).

[0100] Examples of such amine adducts are the corresponding amine-terminated phosphates and, among them, more particularly, amine-terminated ethylhexyl phosphate and amine-terminated phenyl phosphate, very preferably amine-terminated bis(2-ethylhexyl) phosphate. Examples of amines with which the phosphates are terminated are in particular tertiary amines, examples being dicyclic amines such as, for example, diazabicyclooctane (DABCO), diazabicyclononene (DBN), diazabicycloundecene (DBU), dimethyldodecylamine or triethylamine. Particularly preferred for the termination of the phosphates is the use of tertiary amines, which ensure a high activity of the catalyst under curing conditions. Certain amine-terminated phosphoric acid catalysts are also commercially available (e.g., Nacure types from King Industries, such as 4167).

[0101] Preferably, at least one catalyst a4) is selected from phosphorus-containing organic components, more preferably selected from acyclic phosphoric acid diesters, acyclic phosphoric acid monoesters, cyclic phosphoric acid diesters and cyclic phosphoric acid monoesters, wherein each of the above-mentioned phosphoric acid diesters and monoesters can optionally be present in the form of an adduct with at least one amine (i.e., blocked with at least one amine), preferably, at least one tertiary amine is blocked, even more preferably, at least two catalysts are present as at least one catalyst a4), these catalysts are both selected from acyclic phosphoric acid diesters, acyclic phosphoric acid monoesters, cyclic phosphoric acid diesters and cyclic phosphoric acid monoesters, but wherein 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 in the form of an amine adduct (i.e., in unblocked form).

[0102] Preferably, at least 2-ethylhexyl acid phosphate is used as at least one catalyst a4), in particular as at least one catalyst a4) which is not present in the form of an amine adduct, i.e. not in any amine-terminated form. The term "2-ethylhexyl acid phosphate" includes both monoethylhexyl acid phosphate and diethylhexyl acid phosphate.

[0103] Preferably, the amount of catalyst present in the form of an amine adduct exceeds the amount of catalyst not present in the form of an amine adduct. Preferably, the relative weight ratio of catalyst not present in the form of an amine adduct to catalyst present in the form of an amine adduct in component A) is in the range of 0.1 to 1.0 to 0.9:1.0, more preferably 0.2 to 1.0 to 0.8 to 1.0, even more preferably 0.3 to 1.0 to 0.7 to 1.0.

[0104] Preferably, at least two catalysts a4) are present, one catalyst not present in any form of an amine adduct such as 2-ethylhexyl acid phosphate, preferably in an amount in the range of 0.01 to 0.4 wt.-%, and one catalyst present in the form of an amine adduct, preferably in an amount in the range of 0.05 to 1.0 wt.-%.

[0105] Preferably, component A) of the primer coating system comprises the catalyst in the form of an amine adduct in an amount in the range from 0.05 to 2.0 wt.-%, more preferably from 0.06 to 1.8 wt.-%, even more preferably from 0.07 to 1.6 wt.-%, still more preferably from 0.08 to 1.4 wt.-%, yet more preferably from 0.09 to 1.2 wt.-%, particularly preferably from 0.10 to 1.0 wt.-%, in each case based on the total weight of component A).

[0106] Preferably, component A) of the primer coating system comprises the catalyst which is not present in the form of an amine adduct in an amount in the range from 0.01 to 1.0 wt.-%, more preferably from 0.02 to 0.8 wt.-%, even more preferably from 0.03 to 0.6 wt.-%, still more preferably from 0.04 to 0.5 wt.-%, yet more preferably from 0.05 to 0.4 wt.-%, in each case based on the total weight of component A).

[0107] Preferably, component A) of the primer coating system further comprises at least one catalyst a5) which is suitable for crosslinking NCO groups, which catalyst a5) is different from the catalyst a4) and also from each of the components a1) to a3).

[0108] Preferably, the at least one catalyst a5) is suitable for crosslinking the NCO groups of constituent b2) of component B).

[0109] Preferably, component A) of the primer coating system comprises at least one catalyst a5) in an amount in the range from 0.001 to 1.00 wt.-%, more preferably from 0.002 to 0.80 wt.-%, even more preferably from 0.003 to 0.60 wt.-%, still more preferably from 0.004 to 0.40 wt.-%, yet more preferably from 0.005 to 0.20 wt.-%, most preferably from 0.007 to 0.15 wt.-%, in each case based on the total weight of component A).

[0110] Preferably, the catalyst a5) is selected from organometallic catalysts, in particular organotin catalysts. Examples of organotin catalysts are DOTL (dioctyltin dilaurate) and DBTL (dibutyltin dilaurate). DOTL is particularly preferred.

[0111] Additional Ingredients

[0112] Component A) of the primer coating system may optionally contain one or more additional ingredients such as one or more of the ingredients a6) to a8), which are different from each other, from each of the ingredients a1) to a3) and from each of the optional ingredients a4) and a5). Preferably, component A) of the primer coating system contains at least one, preferably at least two, more preferably at least three ingredients a6) to a8).

[0113] Preferably, component A) of the primer coating system comprises

[0114] at least one epoxy resin as constituent a6), preferably in an amount in the range from 0.5 to 15.0 wt.-%, more preferably from 1.0 to 10.0 wt.-%, even more preferably from 1.5 to 7.5 wt.-%, still more preferably from 2.0 to 5.5 wt.-%, in each case based on the total weight of component A),

[0115] and / or

[0116] at least one chlorinated polyolefin as constituent a7), preferably in an amount in the range from 5.0 to 35 wt.-%, more preferably from 6.0 to 30.0 wt.-%, even more preferably from 7.0 to 25.0 wt.-%, still more preferably from 8.0 to 20 wt.-%, in each case based on the total weight of component A),

[0117] and / or

[0118] At least one pigment and / or filler as constituent a8), preferably in an amount in the range from 5.0 to 30 wt.-%, more preferably from 6.0 to 25.0 wt.-%, even more preferably from 7.0 to 20.0 wt.-%, still more preferably from 8.0 to 15 wt.-%, in each case based on the total weight of component A).

[0119] The term "pigment" is known to the skilled person, for example from DIN 55943 (date: October 2001). "Pigment" in the sense of the present invention preferably refers to components in the form of powders or flakes, which are substantially, preferably completely insoluble in the medium surrounding them, such as, for example, in one of the coating compositions used according to the invention. Pigments are preferably colorants and / or substances which can be used as pigments due to their magnetic, electric and / or electromagnetic properties. Pigments differ from "fillers" preferably in their refractive index, the refractive index of pigments being ≥1.7. The term "filler" is known to the skilled person, for example from DIN 55943 (date: October 2001). Pigments can be inorganic or organic.

[0120] Component A) of the primer coating system may optionally comprise one or more additional ingredients such as in addition to one or more ingredients a6) to a8) or as a substitute thereof. Depending on the desired application, component A) may contain one or more conventional additives. For example, it may comprise at least one additive selected from the group consisting of reactive diluents, light stabilizers, antioxidants, degassing agents, emulsifiers, slip additives, polymerization inhibitors, plasticizers, initiators for free radical polymerization, adhesion promoters, flow control agents, film-forming aids, flame retardants, corrosion inhibitors, desiccants, biocides, thickeners, wetting agents, leveling agents and / or matting agents. They may be used in known and conventional proportions. Preferably, their content is 0.01 to 20.0 wt.-%, more preferably 0.05 to 15.0 wt.-%, particularly preferably 0.1 to 10.0 wt.-%, even more preferably 0.1 to 7.5 wt.-%, in particular 0.1 to 5.0 wt.-%, and most preferably 0.1 to 2.5 wt.-%, based on the total weight of the coating composition obtained by mixing components A) and B) and optionally C), in each case based on the total weight of the coating composition.

[0121] In particular, component A) of the primer coating system optionally comprises at least one leveling agent and / or dispersant as additive as component a9). Preferably, a9) is a (meth)acrylate polymer which contains at least one ether segment (preferably in a side chain) and / or at least one siloxane unit (preferably also in a side chain). Preferably, component a9) is present in component A) in a range of 0.10 to 5.0 wt.-%, more preferably 0.50 to 4.0 wt.-%, even more preferably 0.80 to 3.5 wt.-%, in each case based on the total weight of component A).

[0122] Component B)

[0123] Component B) comprises at least two constituents b2) and optionally also a constituent b1) which are different from one another but may additionally comprise further optional constituents.

[0124] Preferably, component B) does not contain any condensates a3), ie the condensates a3) are present only in component A) of the primer coating system.

[0125] Preferably, component B) of the primer coating system has a total solids content of >40 wt.-%, more preferably >45 wt.-%, even more preferably >50 wt.-%, yet more preferably >55 wt.-%, in each case based on the total weight of component B). The total solids content of component B) of the primer coating system is preferably in the range from 45 to 100 wt.-%, more preferably from 50 to <100 wt.-%, even more preferably from 55 to <100 wt.-%, in each case based on the total weight of component B). The total solids content, in other words the non-volatile fraction, is determined according to the method described below.

[0126] Optional ingredient b1)

[0127] Optional ingredient b1) is at least one organic solvent. Examples of such organic solvents include those mentioned above for ingredient a1). Component B) may contain more than one organic solvent b1). The at least one organic solvent b1) may be the same as or different from the at least one organic solvent a1). If more than one organic solvent is used as a1) and / or b1), it may be that a1) and b1) are partly the same and partly different.

[0128] Preferably, the amount of constituent b1) in component B) is in the range from 5 to 50 wt.-%, more preferably from 10 to 40 wt.-%, even more preferably from 15 to 35 wt.-%, in each case based on the total weight of component B).

[0129] Ingredient b2)

[0130] Component b2) is an organic component which carries on average two or more NCO groups. Preferably, component b2) carries on average more than two NCO groups.

[0131] 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. The trimers of IPDI (isophorone diisocyanate) and / or HDI (hexamethylene diisocyanate), i.e. isocyanurates, are particularly preferred.

[0132] 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 above-mentioned polyisocyanates. Suitable polyisocyanate parent structures can be polyisocyanate prepolymers with urethane structural units, which are obtained by the reaction of polyols with stoichiometric excess of the above-mentioned aliphatic polyisocyanates. Particularly preferred polyisocyanate parent structures are hexamethylene diisocyanate and / or its biuret dimer and / or allophanate dimer and / or isocyanurate trimer and / or its uretdione, as well as mixtures of the polyisocyanate parent structures. Particularly preferred polyisocyanate parent structures are hexamethylene diisocyanate and / or its isocyanurate trimer, optionally with its uretdione.

[0133] Suitable cycloaliphatic polyisocyanates are preferably substituted or unsubstituted cycloaliphatic 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 abovementioned polyisocyanates. Suitable polyisocyanate parent structures can be polyisocyanates derived from alicyclic polyisocyanates by trimerization, dimerization, carbamate formation, biuret formation, uretdione formation and / or allophanate formation, more particularly biuret dimer and / or allophanate dimer and / or isocyanurate trimer. The polyisocyanate parent structure can be a polyisocyanate prepolymer with carbamate structural units, which is obtained by the reaction of polyols with a stoichiometric excess of the above-mentioned alicyclic polyisocyanates. Particularly preferred alicyclic polyisocyanates are isophorone diisocyanate and 4,4'-methylene dicyclohexyl diisocyanate and / or its biuret dimer and / or its allophanate dimer and / or its isocyanurate trimer.

[0134] Preferably, component b2) does not contain any silane-modified NCO groups, ie none of its NCO groups preferably react with any silanes. Preferably, component B) itself does not contain any NCO-group-containing components which carry any silane-modified NCO groups.

[0135] Ingredient b3)

[0136] Optionally, component B) of the primer coating system contains at least one optional component b3). The optional component b3) is an organosilane component which is different from each of the components b1) and b2) and carries at least one hydrolyzable group X and preferably also at least one non-hydrolyzable organic residue R and / or T. The optional component b3) is also different from each of the components a1) to a3) of component A). Preferably, the component b3) is used as an adhesion promoter.

[0137] Preferably, the at least one organosilane component b3) is a monosilane and has at least two, particularly preferably at least three, hydrolyzable groups X and / or is at least one bis(silane) which preferably has at least four, particularly preferably six, hydrolyzable groups X.

[0138] Preferably, at least one organosilane b3) is an organosilane of the general formula (I) and / or (II)

[0139] Si(X) 4-y (R) y ,

[0140] (I)

[0141] Si(X) 3-z (T) z -(RA)-Si(X) 3-z (T) z

[0142] (II)

[0143] Wherein in the case of general formula (I)

[0144] X is each independently a hydrolyzable group, preferably each independently selected from OC 1-4 alkyl,

[0145] The parameter y is an integer in the range 1 to 3, but is at least 1, preferably exactly 1, and

[0146] R is a non-hydrolyzable organic residue, preferably an aliphatic residue, which preferably has 1 to 10 carbon atoms, wherein at least one of the residues R optionally contains at least one functional group,

[0147] And wherein in the case of general formula (II)

[0148] X represents in each case independently of one another a hydrolyzable group and is preferably in each case independently of one another selected from OC 1-4 -alkyl,

[0149] RA represents a divalent non-hydrolyzable organic residue, preferably an aliphatic residue, which preferably has 1 to 10 carbon atoms and which preferably contains no functional groups,

[0150] The parameter z is in each case an integer in the range from 0 to 3, preferably in each case 0, and

[0151] T is a non-hydrolyzable organic residue, preferably an aliphatic residue, which preferably has 1 to 10 carbon atoms, which is different from the residue RA, and which optionally comprises at least one functional group.

[0152] Examples of suitable functional groups are, in particular, thiol groups, amino groups, epoxy groups.

[0153] 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-glycidoxypropyl)trimethoxysilane, (3-glycidoxypropyl)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.

[0154] Optional component C)

[0155] Optional component C) is a reducing agent component and comprises at least one organic solvent c1). Component C) is used to dilute the coating composition to be prepared and for this reason comprises at least one organic solvent c1) and preferably consists of at least one organic solvent c1). Examples of such organic solvents include those mentioned above for components a1) and b1). Component C) may comprise more than one organic solvent c1). At least one organic solvent c1) may be the same or different from at least one organic solvent a1) and / or b1). If more than one organic solvent is used as a1) and / or b1) and / or c1), it may be that a1) and / or b1) and / or c1) are partly the same and partly different.

[0156] Primer coating composition

[0157] The primer coating composition is

[0158] Obtainable by mixing at least components A) and B) and optionally C) of the primer coating system with one another (first alternative)

[0159] or a primer coating composition comprising at least components (i), (ii) and (iii) and optionally also (iv), which are different from one another (second alternative), namely

[0160] (i) at least one organic solvent, which preferably corresponds to at least one organic solvent a), b1) and / or c1) as defined for the primer coating system of the invention,

[0161] (ii) at least one film-forming polymer which is self-crosslinking or externally crosslinking, preferably externally crosslinking, more preferably which corresponds to the at least one polymer a2) containing functional groups reactive toward NCO groups as defined for the primer coating system of the invention,

[0162] (iii) at least one condensation product corresponding to the condensation product a3) as defined for the primer coating system of the invention, and

[0163] (iv) at least in case the at least one film-forming polymer (ii) is an externally crosslinked polymer, optionally at least one crosslinking agent, preferably selected from blocked polyisocyanates, melamine formaldehyde resins and mixtures thereof.

[0164] The preparation of the coating composition of the first alternative can be carried out using customary and known preparation methods and mixing methods and mixing units, or using conventional dissolvers and / or stirrers.

[0165] All preferred embodiments described above in conjunction with the primer coating system and preferred embodiments thereof are also preferred embodiments of the primer coating composition.

[0166] Preferably, the primer coating composition is a solvent-borne, i.e. a coating composition based on an organic solvent, preferably due to the presence of components a1) and b1) and optionally c1). For the purposes of the present invention, the term "solvent-borne" in relation to the coating composition is preferably understood to mean an organic solvent as mentioned above, as solvent and / or as diluent, as the main component of all solvents and / or diluents present therein, preferably in an amount of at least 35 wt.-%, based on the total weight of the coating composition. Thus, preferably, the coating composition is not water-based, i.e. not an aqueous coating composition.

[0167] The primer coating composition preferably comprises an organic solvent fraction of at most 75 wt.-%, more preferably at most 70 wt.-%, even more preferably at most 65 wt.-%, still more preferably at most 60 wt.-%, in each case based on the total weight of the coating composition. All customary organic solvents known to the person skilled in the art can be used as organic solvent, i.e. as components a1) and b1) and optionally c1). The term "organic solvent" is known to the person skilled in the art, in particular from Council Directive 1999 / 13 / EC of 11 March 1999. Examples of organic solvents that can be used have already been mentioned above in conjunction with components a1) and b1) and c1). Preferably, the primer coating composition comprises an organic solvent fraction in the range of 30 to 70 wt.-%, based on the total weight of the coating composition.

[0168] Preferably, the primer coating composition has a total solids content of >25 wt.-%, more preferably >30 wt.-%, even more preferably >35 wt.-%, in each case based on the total weight of the coating composition.

[0169] The total solids content of the primer coating composition is preferably in the range of >20 to 60 wt.-%, more preferably >25 to 55 wt.-%, even more preferably >30 to 50 wt.-%, yet more preferably >30 to 45 wt.-%, in each case based on the total weight of the coating composition. The total solids content, in other words the non-volatile fraction, is determined according to the method described below.

[0170] Preferably, the primer coating composition is obtainable by mixing components A) and B) in a weight ratio (component A) / component B)) in the range of 25:1 to 1:1. More preferably, the mixing is carried out in a weight ratio in the range of 20:1 to 1.1:1, even more preferably in a weight ratio in the range of 17.5:1 to 2:1, in particular in a weight ratio in the range of 15:1 to 3:1.

[0171] Preferably, the primer coating composition contains an excess of component b2), which carries on average two or more NCO groups, so that when said component migrates into the intermediate coating film, preferably into the primer coating film applied on top of the primer coating film obtained from the primer coating composition on the substrate, at least partial curing of the intermediate coating film is achieved when said intermediate coating film contains at least one, preferably polymeric component, which contains functional groups reactive toward NCO groups. In this context, the term "excess" preferably means a molar or mass excess, more preferably a mass excess.

[0172] The term "excess ingredient b2)" preferably means that after mixing, ingredient b2) originating from component "B" is still present in the resulting primer coating composition in an amount of 5 to 20 wt.-%, preferably 7.5 to 15 wt.-%, more preferably 10 to 12.5 wt.-%, based in each case on the total weight of ingredient b2) originally present in said component B), which, due to the use of an overstoichiometric amount of ingredient b), is not used for crosslinking with related ingredients, such as ingredient a2) of component A). Thus, when applied on top of the primer coating film obtainable by applying the primer coating material composition to the surface of the substrate, the subsequently applied primer coating film can also be at least partially cured by NCO migration.

[0173] The primer coating composition of the invention according to the second alternative is a 1K (one-component) coating composition which does not require mixing of any of its components shortly before application, as in the case of the primer coating system of the invention. Preferably, the 1K primer coating composition of the second alternative does not contain any free polyisocyanates, i.e. any components with unblocked NCO groups.

[0174] The 1K primer coating composition of the second alternative contains at least one organic solvent as component (i). The same solvents as defined above for components a1), b1) and c1) can also be used as component (i).

[0175] The 1K-primer coating composition of the second alternative may contain any additional ingredients defined above as being present as ingredients in component A) of the primer coating system, including, for example, any of ingredients a4) to a9). All preferred embodiments described above in conjunction with any of these ingredients present in the primer coating system are also preferred embodiments when present in the 1K-primer coating composition of the second alternative.

[0176] The 1K primer coating composition of the second alternative contains at least one condensation product as component (iii), which corresponds to the condensation product a3) as defined above for the primer coating system of the invention. All preferred embodiments described above in conjunction with the condensation product a3) present in the primer coating system are also preferred embodiments of the condensation product a3) present in the 1K primer coating composition of the second alternative.

[0177] Preferably, the 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 wt.-%, more preferably 2.0 to 20.0 wt.-%, even more preferably 3.0 to 17.5 wt.-%, yet more preferably 4.0 to 15.0 wt.-%, still more preferably 5.0 to 14.0 wt.-%, even more preferably 6.0 to 13.0 wt.-%, most preferably 7.0 to 12.0 wt.-%, based on the total weight of the primer coating composition.

[0178] The 1K primer coating composition of the second alternative contains at least one film-forming polymer which is self-crosslinking or externally crosslinked, preferably externally crosslinked, more preferably corresponding to at least one polymer a2 containing functional groups reactive toward NCO groups as defined for the primer coating system of the invention). At least in the case where at least one film-forming polymer (ii) is an externally crosslinked polymer, it optionally further comprises at least one crosslinker. The at least one crosslinker is preferably selected from blocked polyisocyanates, melamine formaldehyde resins and mixtures thereof. All preferred embodiments described above in conjunction with the polymer a2) present in the primer coating system are also preferred embodiments of the polymer component (ii) present in the 1K primer coating composition of the second alternative.

[0179] Use of primer coating compositions

[0180] Another subject of the present invention is the use of the primer coating composition of the invention for improving the water resistance and / or moisture resistance of a cured primer coating film obtainable therefrom and / or a cured multi-layer coating system containing at least one cured primer coating film, the cured primer coating film being obtainable from the primer coating composition. This improvement can be attributed in particular to the presence of component a3).

[0181] All preferred embodiments described above in conjunction with the primer coating system and the primer coating composition and in each case preferred embodiments thereof are also preferred embodiments of the above-mentioned use.

[0182] Method for coating a substrate

[0183] Another subject of the present invention is a method for coating a substrate, comprising at least step 1) and optionally step (1a), namely

[0184] 1) applying the primer coating composition of the present invention at least partially to at least one surface of an optionally pre-coated substrate and forming a primer coating film on the surface,

[0185] 1a) and optionally at least one further step 1a): curing the at least one primer coating film obtained after step 1) to obtain at least one cured primer coating on said surface.

[0186] All preferred embodiments described above in conjunction with the primer coating system, the primer coating composition and the abovementioned uses as well as preferred embodiments thereof in each case are also preferred embodiments of the abovementioned method.

[0187] Preferably, step 1) is performed via spray application.

[0188] The primer coating film formed on the optional 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. In the case of a metal substrate, a primer is typically applied after the substrate has a cured electrodeposition coating. In this case, the cured electrodeposition coating film is present below the primer coating film and is preferably adjacent to the primer coating film. This is an example of a pre-coated substrate. In the case of a non-metallic substrate (such as a plastic substrate including a fiber-reinforced plastic substrate), the primer coating film typically represents the first coating film applied to its surface.

[0189] Preferably, step 1a) is carried out at a temperature in the range of 30° C. to 180° C., more preferably in the range of 35° C. to 170° C., even more preferably in the range of 40° C. to 140° C., still more preferably in the range of 40° C. to 130° C., in each case preferably for a period of 5 to 45 minutes, more preferably for a period of 10 to 40 minutes, in particular for a period of 12.5 to 35 minutes, most preferably for a period of 15 to 30 minutes. Most preferably, in particular when using plastic substrates or fiber-reinforced plastic substrates, step 1a) is carried out at a temperature of not more than 80° C., preferably not more than 70° C., more preferably not more than 60° C., even more preferably not more than 55° C. Prior to step 1a), the primer coating film may optionally be flashed, preferably for a period of 1 to 20 minutes, more preferably for a period of 1.5 to 15 minutes, still more preferably for a period of 2 to 12 minutes, yet more preferably for a period of 5 to 11 minutes, most preferably for a period of 8 to 10 minutes. Preferably, the flash evaporation is carried out at a temperature not exceeding 40°C, more preferably at a temperature in the range of 18°C ​​to 30°C.

[0190] In the sense of the present invention, the term "flash" means drying, wherein at least some of the solvent and / or water evaporates from the coating film (ie from the formed primer coating) before any curing takes place. Curing does not take place by flashing.

[0191] 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.

[0192] The method is particularly suitable for the coating of automobile bodies or parts thereof (including corresponding metal substrates, but also plastic substrates such as polymer substrates and fiber-reinforced plastic substrates). Therefore, the preferred substrate is an automobile body or parts thereof.

[0193] Suitable as metal substrates for use according to the present invention are all substrates commonly used and known by technicians. The substrate used according to the present invention is preferably a metal substrate, more preferably selected from the group consisting of steel, preferably selected from the steel, aluminum and magnesium of the group consisting of bare steel, cold rolled steel (CRS), hot rolled steel, galvanized steel (such as hot dip galvanized steel (HDG)), alloy galvanized steel (for example, Galvalume, Galvannealed or Galfan) and aluminized steel, and also Zn / Mg alloy and Zn / Ni alloy. Particularly suitable substrates are parts of the body of the car for production or the entire body of the car. The metal substrate may have been pretreated with at least one metal phosphate such as zinc phosphate and / or pretreated with at least one oxalate. This pretreatment using phosphating or oxalating is usually carried out after the substrate is cleaned and before the substrate is coated by electrodeposition, which is particularly a pretreatment step commonly used in the automotive industry. The metal substrate may further include a cured electrodeposition coating as a precoat.

[0194] Preferably, thermoplastic polymers are used as plastic substrates. Suitable polymers are poly(meth)acrylates (including poly(methyl)acrylate, poly(butyl)acrylate), polyethylene terephthalate, polybutylene terephthalate, polyvinylidene fluoride, polyvinyl chloride, polyesters (including 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-acrylate copolymer) and ABS (acrylonitrile-butadiene-styrene copolymer), polyetherimide, phenolic resin, urea resin, melamine resin, alkyd resin, epoxy resin, polyurethane (including TPU), polyetherketone, polyphenylene sulfide, polyether, polyvinyl alcohol, and mixtures thereof. Polycarbonate and poly(meth)acrylate are particularly preferred.

[0195] In addition, and most preferably, a fiber-reinforced plastic substrate is used. Glass and / or carbon fibers can be used in particular for reinforcement, most preferably carbon fibers. An example of a suitable carbon fiber-reinforced plastic substrate is a carbon fiber-reinforced polyamide substrate.

[0196] Coated substrate

[0197] Another subject of the present invention is a coated substrate obtainable by the process.

[0198] All preferred embodiments described above in conjunction with the primer coating system, the primer coating composition, the abovementioned use and the method and in each case preferred embodiments thereof are also preferred embodiments of the coated substrate.

[0199] Method for preparing a multi-layer coating system

[0200] Another subject of the present invention is a method for producing a multilayer coating system on at least one surface of an optionally precoated substrate, the method comprising at least steps 1) to 3) and optionally 4), namely

[0201] 1) applying a first coating composition at least partially to at least one surface of an optionally pre-coated substrate and forming a first coating film on said surface, wherein the first coating composition is said primer coating composition,

[0202] 2) applying at least one base coating 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 forming a second coating film preferably adjacent to the first coating film, and

[0203] 3) applying a top coating composition, preferably a clear coating 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 forming a third coating film, which is preferably adjacent to the second coating film and is preferably the outermost coating film of the formed multi-layer coating system, and

[0204] 4) optionally co-curing the first, second and third coating films to obtain a multi-layer coating system comprising cured first, second and third coatings.

[0205] All preferred embodiments described above in conjunction with the primer coating system, the primer coating composition, the abovementioned use and method and the coated substrate and in each case preferred embodiments thereof are also preferred embodiments of the method for producing the multilayer coating system.

[0206] The method comprises at least steps (1), (2), (3) and optionally (4). However, the method may comprise further additional optional steps.

[0207] Preferably, each of steps 1) to 3) is performed via spray application.

[0208] The first, second and third coating films formed on the optionally pre-coated substrate by performing steps 1), 2) and 3) are preferably each an uncured coating film at this stage. Therefore, preferably, the first, second and third coating compositions are all applied wet-on-wet.

[0209] Preferably, the method of the present invention further comprises a step 1b), which is performed after step 1) and before step 2). In said step 1b), before applying the second coating composition in step 2), the first coating film obtained after step 1) is flashed, preferably for a period of 1 to 20 minutes, more preferably for a period of 1.5 to 15 minutes, still more preferably for a period of 2 to 12 minutes, still more preferably for a period of 5 to 11 minutes, most preferably for a period of 8 to 10 minutes. Preferably, step 1b) is performed at a temperature not exceeding 40°C, more preferably at a temperature in the range of 18°C ​​to 30°C.

[0210] The second coating film is a primer film. Therefore, the second coating composition is a primer composition. The term "primer" is known to those skilled in the art and is used, for example, in Lexikon, paints and printing inks, Georg Thieme Verlag, 1998, 10th edition, page 57. Thus, basecoats are used in particular for the coloring of automotive paints and general industrial paints in order to provide coloring and / or optical effects by using the basecoat as an intermediate coating composition. This is usually applied to a metal or plastic substrate, optionally pre-coated in each case. In order to protect the basecoat film, in particular from environmental influences, at least one additional topcoat, preferably a clearcoat film, is applied thereto. The term "clearcoat" is also known to those skilled in the art and refers to the transparent outermost layer of a multilayer coating structure applied to a substrate.

[0211] Preferably, the method further comprises a step 2a), which is performed after step 2) and before step 3). In said step 2a), before applying the third coating composition in step 3), the second coating film obtained after step 2) is flashed, preferably for a period of 1 to 20 minutes, more preferably for a period of 1.5 to 15 minutes, still more preferably for a period of 2 to 12 minutes, still more preferably for a period of 5 to 11 minutes, most preferably for a period of 8 to 10 minutes. Preferably, step 2a) is performed at a temperature not exceeding 40°C, more preferably at a temperature in the range of 18°C ​​to 30°C.

[0212] Preferably, the method further comprises step 3a), which is performed after step 3) and before step 4). In said step 3a), before performing the curing step 4), the third coating film obtained after step 3) is flashed, preferably for a period of 1 to 20 minutes, more preferably for a period of 3 to 15 minutes, and especially for a period of 7 to 12 minutes. Preferably, step 3a) is performed at a temperature not exceeding 40° C., more preferably at a temperature in the range of 18° C. to 30° C.

[0213] In step 4), the first, second and third coating films are co-cured, ie cured together at the same time. The cured third coating film preferably represents the outermost layer of the formed multilayer coating system obtained after step 4).

[0214] Each resulting cured coating film represents a coating. Thus, after performing step 4), the first, second and third coatings are formed on the optionally pre-coated substrate, wherein the third layer is preferably the outermost layer of the formed multilayer coating system. The first layer L1 is obtainable from the first coating film, the second layer L2 is obtainable from the second coating film, and the third layer L3 is obtainable from the third coating film.

[0215] Preferably, step 4) is carried out at a temperature in the range of 30° C. to 180° C., more preferably in the range of 35° C. to 170° C., even more preferably in the range of 40° C. to 140° C., still more preferably in the range of 40° C. to 130° C., in each case preferably for a period of 5 to 45 minutes, more preferably for a period of 10 to 40 minutes, in particular for a period of 12.5 to 35 minutes, most preferably for a period of 15 to 30 minutes. Most preferably, in particular when using plastic substrates or fiber-reinforced plastic substrates, step 4) is carried out at a temperature of not more than 80° C., preferably not more than 70° C., more preferably not more than 60° C., even more preferably not more than 55° C. The temperature is in each case the substrate temperature, which is preferably measured with a thermocouple.

[0216] Preferably, the cured primer film (layer L1) obtained after step 4) has been carried out has a dry film thickness in the range of 10 to 35 μm. Preferably, the cured basecoat film (layer L2) obtained after step 4) has been carried out has a dry film thickness in the range of 12 to 35 μm. Preferably, the cured topcoat, in particular clearcoat film (layer L3) obtained after step 4) has been carried out has a dry film thickness in the range of 30 to 60 μm.

[0217] Basecoat and topcoat compositions

[0218] In step 2), any type of basecoat composition can be used, for example 1K or 2K basecoat compositions, preferably 1K compositions, which can be solvent-borne or aqueous and can contain coloring and / or effect pigments. Preferably, the basecoat composition comprises at least one film-forming binder, preferably at least one polymer, more preferably at least one polymer having functional groups reactive toward NCO groups. Optionally, the basecoat composition can comprise at least one crosslinker, preferably selected from melamine formaldehyde resins and / or preferably blocked polyisocyanates, in particular in the case where at least the film-forming binder is an externally crosslinked polymer.

[0219] In step 3), any type of topcoat, preferably clearcoat composition, such as a 1K- or 2K-clearcoat composition, preferably a 2K-clearcoat composition, can be used, which can be solvent-based or water-based, but is preferably solvent-based.

[0220] Preferably, a 2K clearcoat composition is used, more preferably a corresponding clearcoat composition, which is obtainable from a suitable clearcoat coating system comprising at least two components D) and E) and optionally at least one further component F), which are different from one another and are separated from one another. Preferably, component D) comprises at least components d1) to d4), which are different from one another, 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 d3), which has a glass transition temperature (T g ) is lower than the glass transition temperature (T g ), wherein the amount of component d2) in component D) exceeds the amount of component d3), and at least one catalyst d4) suitable for crosslinking the NCO groups, which is selected from organotin catalysts and is identical to or different from catalyst a3). Preferably, component E) comprises at least two components e1) and e2), which are different from each other, namely at least one organic solvent e1), and at least one organic component e2) which carries on average two or more NCO groups, wherein at least a portion of these NCO groups have been reacted with at least one organosilane before the incorporation of component e2) into component E), and wherein the optional component F) is a reducing agent component and comprises at least one organic solvent f1). Preferably, both components D) and E) and optionally F) of the clearcoat system are clear, i.e. transparent. Of course, preferably, the clearcoat composition obtainable therefrom is also clear, i.e. transparent. In particular, none of the components D) and E) and optionally F) of the coating system contains any pigments and / or fillers, in particular any pigments and / or fillers which impart color and / or effects. Of course, this preferably also applies to the clearcoat composition.

[0221] Ingredients d1)

[0222] Ingredient d1) is at least one organic solvent. Examples of such organic solvents include those mentioned above for ingredients a1) and b1) and c1). Component D) may contain more than one organic solvent d1). The at least one organic solvent d1) may be the same or different from the at least one organic solvent a1) and / or b1) and / or c1). If more than one organic solvent is used as a1) and / or b1) and / or c1) and / or d1), a1) and b1) and / or c1) and / or d1) may be partly the same and partly different.

[0223] Ingredients d2) and d3)

[0224] 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). The at least one OH-functional (meth)acrylic polymer d3) has a glass transition temperature (T g ) is lower than the glass transition temperature (T g ). The amount of component d2) in component D) exceeds the amount of component d3), that is, the component D) has a higher T g The (meth)acrylic polymer d2) (higher than the (meth)acrylic polymer d3)) is present in component D) in an amount higher than the (meth)acrylic polymer d3). T is measured according to the method disclosed in the 'Methods' section g .

[0225] Preferably, the at least one OH-functional (meth)acrylic polymer d2) present in component D) of the clearcoat system has a glass transition temperature (Tg) in the range of +10°C to +75°C, preferably +15°C to +70°C, more preferably +20°C to +65°C, still more preferably +25°C to +60°C, even more preferably +30°C to +55°C, most preferably +35°C or +40°C to +50°C. g Preferably, the at least one OH-functional (meth)acrylic polymer d3) present in component D) of the clearcoat 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, still more preferably -45°C to 0°C, even more preferably -40°C to 0°C, yet more preferably -35°C or -30°C to -5°C, most preferably -25°C or -5°C. g ).

[0226] The OH-functional (meth) acrylic polymers d2) and d3) preferably each contain on average two or more OH groups. Preferably, each of the OH-functional (meth) acrylic polymers d2) and d3) has an OH value of 30 to 400 mg KOH / g, more particularly between 100 and 300 KOH / g. Preferably, each of the components d2) and d3) has a weight average molecular weight M of preferably between 800 and 100 000 g / mol, more particularly between 1000 and 75 000 g / mol, measured by gel permeation chromatography (GPC) against polystyrene standards. w .

[0227] The term (meth)acrylic polymer comprises in each case both homopolymers and copolymers, but preferably means copolymers.

[0228] The term "(meth)acryloyl" or "(meth)acrylate" or "(meth)acrylic" in the context of the present invention includes in each case the meaning "methacryloyl" and / or "acryloyl", "methacrylic" and / or "acrylic" or "methacrylate" and / or "acrylate". Thus, a "(meth)acrylic copolymer" may generally be formed from only "acrylic monomers", only "methacrylic monomers" or "acrylic and methacrylic monomers". However, polymerizable monomers other than acrylic and / or methacrylic monomers (e.g. styrene, etc.) may also be contained in the "(meth)acrylic copolymer". In other words, the (meth)acrylic polymer may consist exclusively of acrylic and / or methacrylic monomer units, but this is not mandatory. The notation "(meth)acrylate polymer or copolymer" or "(meth)acrylic polymer or copolymer" is 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 (meth)acrylate groups. In the preparation of (meth)acrylic copolymers, preferably more than 50% or 75% of the monomers thus have (meth)acrylate groups. However, the use of further monomers as comonomers such as copolymerizable vinyl monomers (eg styrene) for their preparation is not excluded.

[0229] In order to introduce OH-functionality, hydroxyl-containing monomers can be used, including hydroxyalkyl esters of acrylic acid or methacrylic acid. 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 ε-caprolactone, and other hydroxyalkyl (meth) acrylates with branched or linear alkyl groups up to about 10 carbons and mixtures of these, wherein the term "(meth) acrylate" indicates either or both of methacrylate and acrylate. Generally, it is preferred that at least about 5% by weight of hydroxyl-functional monomers be included in the polymer. Hydroxyl groups on vinyl polymers such as acrylic polymers can be produced by other means, such as ring-opening of glycidyl groups (e.g., glycidyl methacrylate from copolymerization) by organic acids or amines.

[0230] Hydroxyl functional groups can also be introduced through thiol compounds, including but not limited to 3-mercapto-1-propanol, 3-mercapto-2-butanol, 11-mercapto-1-undecanol, 1-mercapto-2-propanol, 2-mercaptoethanol, 6-mercapto-1-hexanol, 2-mercaptobenzyl alcohol, 3-mercapto-1,2-propylene glycol, 4-mercapto-1-butanol and combinations thereof. Any of these methods can be used to prepare useful hydroxyl-functional (meth) acrylic polymers.

[0231] Examples of suitable comonomers that may be used include, but are not limited to, α,β-ethylenically unsaturated monocarboxylic acids containing 3 to 5 carbon atoms, such as acrylic acid, methacrylic acid and crotonic acid and alkyl and cycloalkyl esters, nitriles and amides of acrylic acid, methacrylic acid and crotonic acid; α,β-ethylenically unsaturated dicarboxylic acids containing 4 to 6 carbon atoms and anhydrides, monoesters and diesters of these acids; vinyl esters, vinyl ethers, vinyl ketones and aromatic or heterocyclic aliphatic vinyl compounds. Representative examples of suitable esters of acrylic acid, methacrylic acid, and crotonic acid include, but are not limited to, esters derived from reactions with saturated fatty alcohols containing from 1 to 20 carbon atoms, such as the methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, tert-butyl, hexyl, 2-ethylhexyl, dodecyl, 3,3,5-trimethylhexyl, stearyl, lauryl, cyclohexyl, alkyl-substituted cyclohexyl esters, alkanol-substituted cyclohexyl esters, such as 2-tert-butyl and 4-tert-butyl cyclohexyl, 4-cyclohexyl-1-butyl ester, and the like. esters, 2-tert-butyl cyclohexyl ester, 4-tert-butyl cyclohexyl ester, 3,3,5,5,-tetramethylcyclohexyl ester, tetrahydrofurfuryl ester and isobornyl ester; unsaturated dialkanoic acids and anhydrides, such as fumaric acid, maleic acid, itaconic acid and anhydrides and monoesters and diesters thereof with alcohols (such as methanol, ethanol, propanol, isopropanol, butanol, isobutanol and tert-butanol), such as maleic anhydride, dimethyl maleate and monohexyl maleate; vinyl acetate, vinyl propionate, vinyl ethyl ether and vinyl ethyl ketone; styrene, α-methylstyrene, vinyltoluene, 2-vinylpyrrolidone and p-tert-butylstyrene.

[0232] (Meth) acrylic polymers can be prepared using conventional techniques, such as by 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. Typical initiators are organic peroxides such as dialkyl peroxides such as di-tert-butyl peroxide, peroxyesters such as tert-butyl peroxy 2-ethylhexanoate and tert-butyl peracetate, peroxydicarbonates, diacyl peroxides, hydroperoxides such as tert-butyl hydroperoxide and peroxyketals; azo compounds such as 2,2′azobis(2-methylbutyronitrile) and 1,1′-azobis(cyclohexanecarbonitrile); and combinations of these. Typical chain transfer agents are mercaptans such as octyl mercaptan, n- or tert-dodecyl mercaptan; halogenated compounds, thiosalicylic acid, thioglycolic acid, mercaptoethanol and other mercaptans already mentioned, as well as dimeric alpha-methylstyrene.

[0233] The polymerization reaction is usually carried out at a temperature of about 20°C to about 200°C. The reaction can be conveniently carried out at a temperature at which the solvent or solvent mixture is refluxed, although a temperature below reflux can be maintained under appropriate control. The initiator should be selected to match the temperature at which the reaction is carried out so that the half-life of the initiator at this temperature should preferably not exceed about thirty minutes. Additional details of general addition polymerization and the polymerization of a mixture including (meth) acrylate monomers are readily available in the polymer field. Usually the solvent or solvent mixture is heated to the reaction temperature, and the monomer and initiator are added at a controlled rate over a period of time (usually between 2 and 6 hours). During this time, a chain transfer agent or another solvent may also be fed at a controlled rate. The temperature of the mixture is then maintained for a period of time to complete the reaction. Alternatively, another initiator may be added to ensure complete conversion.

[0234] Ingredient d2) is preferably present in component D) in an amount in the range of 5.0 wt.-% to 85.0 wt.-%, based on the total weight of component (D). More preferably, ingredient d2) is present in component D) in an amount in the range of 10.0 wt.-% to 80.0 wt.-%, yet more preferably 15.0 wt.-% to 75.0 wt.-%, in each case based on the total weight of component D).

[0235] Ingredient d3) is preferably present in component D) in an amount in the range of 5.0 wt.-% to 85.0 wt.-%, based on the total weight of component (D). More preferably, ingredient d3) is present in component D) in an amount in the range of 10.0 wt.-% to 80.0 wt.-%, yet more preferably 15.0 wt.-% to 75.0 wt.-%, in each case based on the total weight of component D).

[0236] Ingredients d4)

[0237] Component d4) is at least one catalyst d4) which is suitable for crosslinking NCO groups and which is selected from organotin catalysts. The catalyst d4) can be identical to or different from the catalyst a5). Preferably, the catalysts d4) and a5) are identical.

[0238] In addition to the catalyst d4), component D) may comprise at least one further organometallic catalyst, such as, for example, an organobismuth catalyst. Preferably, however, if such at least one further organometallic catalyst, such as an organobismuth catalyst, is additionally present in component D), its amount is less than the amount of catalyst d4). More preferably, however, component D) does not comprise any further organometallic catalyst in addition to catalyst d4), and in particular does not comprise any organobismuth catalyst. Preferably, at least one catalyst d4) suitable for crosslinking the NCO groups of constituent e2) of component E), in particular, is present in component D) of the clearcoat system in an amount in the range of 0.001 to 3.00 wt.-%, preferably 0.01 to 2.50 wt.-%, more preferably 0.05 to 2.00 wt.-%, even more preferably 0.10 to 1.50 wt.-%, yet more preferably 0.20 to 1.25 wt.-%, most preferably 0.30 to 1.00 wt.-%, based on the total weight of component D). The catalyst d4) is selected from organotin catalysts. Examples of organotin catalysts are DOTL (dioctyltin dilaurate) and DBTL (dibutyltin dilaurate). DOTL is particularly preferred.

[0239] Optional ingredient d5)

[0240] Preferably, component D) of the clearcoat system further comprises at least one catalyst d5), which is preferably suitable for crosslinking of Si-containing functional groups, the catalyst d5) being different from each of the components d1) to d4). The catalyst d5) may be the same as or different from the catalyst a4).

[0241] Preferably, the at least one catalyst d5) is suitable for crosslinking the Si-containing functional groups present in constituent e2) of component E).

[0242] Preferably, component D) of the clearcoat system comprises at least one catalyst d5) in an amount in the range of 0.01 to 6.00 wt.-%, preferably 0.10 to 5.50 wt.-%, more preferably 0.40 to 5.00 wt.-%, still more preferably 0.70 to 4.50 wt.-%, yet more preferably 1.00 to 4.00 wt.-%, most preferably 1.10 to 3.75 wt.-%, based on the total weight of component D).

[0243] Preferably, at least one catalyst d5) is a phosphorus-containing catalyst and / or a phosphorus-containing and nitrogen-containing catalyst. It is possible to use more than one, for example two different catalysts as catalyst d5).

[0244] 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. More particularly, however, substituted phosphoric acid monoesters and diesters, preferably selected from the group consisting of acyclic phosphoric acid diesters and monoesters and cyclic phosphoric acid diesters and monoesters, which in each case may be amine adducts, for example amine adducts of phosphoric acid monoesters and diesters, are used as at least one catalyst d5).

[0245] Examples of such amine adducts are the corresponding amine-terminated phosphates and, among them, more particularly, amine-terminated ethylhexyl phosphate and amine-terminated phenyl phosphate, very preferably amine-terminated bis(2-ethylhexyl) phosphate. Examples of amines with which the phosphates are terminated are in particular tertiary amines, examples being dicyclic amines such as, for example, diazabicyclooctane (DABCO), diazabicyclononene (DBN), diazabicycloundecene (DBU), dimethyldodecylamine or triethylamine. Particularly preferred for the termination of the phosphates is the use of tertiary amines, which ensure a high activity of the catalyst under curing conditions. Certain amine-terminated phosphoric acid catalysts are also commercially available (e.g., Nacure types from King Industries, such as 4167).

[0246] Preferably, at least one catalyst d5) is selected from phosphorus-containing organic components, more preferably selected from acyclic phosphoric acid diesters, acyclic phosphoric acid monoesters, cyclic phosphoric acid diesters and cyclic phosphoric acid monoesters, wherein each of the above-mentioned phosphoric acid diesters and monoesters can optionally be present in the form of an adduct with at least one amine (i.e., blocked with at least one amine), preferably, at least one tertiary amine is blocked, even more preferably, at least two catalysts are present as at least one catalyst d5), these catalysts are both selected from acyclic phosphoric acid diesters, acyclic phosphoric acid monoesters, cyclic phosphoric acid diesters and cyclic phosphoric acid monoesters, but wherein 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 in the form of an amine adduct (i.e., in unblocked form).

[0247] Preferably, at least two catalysts d5) are present, one catalyst not present in any form of an amine adduct such as 2-ethylhexyl acid phosphate, preferably in an amount in the range of 0.05 to 3.5 wt.-%, more preferably 0.10 to 3.0 wt.-%, still more preferably 0.50 to 2.0 wt.-% or to 1.5 wt.-%, and one catalyst present in the form of an amine adduct, preferably in an amount in the range of 1.0 to 4.0 wt.-%, more preferably 1.0 to 3.0 wt.-%. Preferably, the amount of catalyst present in the form of an amine adduct exceeds the amount of catalyst not present in the form of an amine adduct.

[0248] Preferably, at least 2-ethylhexyl acid phosphate is used as at least one catalyst d5), in particular as at least one catalyst d5), which is not present in the form of an amine adduct, i.e. not in any amine-terminated form. The term "2-ethylhexyl acid phosphate" includes both monoethylhexyl acid phosphate and diethylhexyl acid phosphate.

[0249] Additional Ingredients

[0250] Component D) may optionally comprise one or more additional ingredients. Depending on the desired application, component D) may contain one or more conventional additives. For example, it may comprise at least one additive selected from the group consisting of reactive diluents, light stabilizers, antioxidants, degassing agents, emulsifiers, slip additives, polymerization inhibitors, plasticizers, initiators for free radical polymerization, adhesion promoters, flow control agents, film-forming aids, flame retardants, corrosion inhibitors, desiccants, biocides, thickeners, wetting agents, leveling agents and / or matting agents. They may be used in known and conventional ratios. Preferably, their content is 0.01 to 20.0 wt.-%, more preferably 0.05 to 15.0 wt.-%, particularly preferably 0.1 to 10.0 wt.-%, even more preferably 0.1 to 7.5 wt.-%, in particular 0.1 to 5.0 wt.-%, and most preferably 0.1 to 2.5 wt.-%, based on the total weight of the coating composition obtained by mixing components D) and E) and optionally F), in each case based on the total weight of the coating composition.

[0251] Component D) may further contain one or more additional (meth) acrylic polymers different from both d2) and d3), which may also be OH-functional, but not necessarily. Component D) may contain one or more additional film-forming polymers suitable as adhesive components, such as polyesters and / or polyurethanes. Suitable polyesters are described, for example, in EP-A-0994 117 and EP-A-1 273 640. Polyurethane polyols are preferably prepared by reaction of polyester polyol prepolymers with suitable di- and / or polyisocyanates and are described, for example, in EP-A-1 273 640.

[0252] Component E)

[0253] Component E) comprises at least two ingredients e1) and e2), which are different from one another, but may additionally comprise further optional ingredients. Preferably, component E) of the clearcoat system has a total solids content of >40 wt.-%, more preferably >45 wt.-%, even more preferably >50 wt.-%, yet more preferably >55 wt.-%, in each case based on the total weight of component E). The total solids content of component E) of the clearcoat system is preferably in the range of 45 to 100 wt.-%, more preferably 50 to <100 wt.-%, even more preferably 55 to <100 wt.-%, in each case based on the total weight of component E). The total solids content, in other words the non-volatile fraction, is determined according to the method described below.

[0254] Ingredients e1)

[0255] Ingredient e1) is at least one organic solvent. Examples of such organic solvents include those mentioned above for components a1) and b1) and c1) and d1. Component E) may contain more than one organic solvent e1). At least one organic solvent e1) may be the same or different from at least one organic solvent a1) and / or b1) and / or c1) and / or d1). If more than one organic solvent is used as a1) and / or b1) and / or c1) and / or d1) and / or e1), a1) and b1) and / or c1) and / or d1) and / or e1) may be partly the same and partly different.

[0256] Ingredient e2)

[0257] Component e2) is an organic component which carries on average two or more NCO groups, wherein at least some of these NCO groups have been reacted with at least one organosilane before component e2) is incorporated into component E).

[0258] Examples of component 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.

[0259] Preferably, at least one component e2) of component E) of the clearcoat system carries at least one structural unit of the formula (I)

[0260] -NR-(X-SiR” x (OR') 3-x )(I),

[0261] and / or, preferably and, at least one structural unit having formula (II)

[0262] -N(X-SiR”x (OR') 3-x ) n (X'-SiR" y (OR') 3-y ) m (II)

[0263] in:

[0264] R = hydrogen, alkyl, cycloalkyl, aryl or aralkyl, the carbon chain may be replaced by non-adjacent oxygen, sulfur or NR a Group interruption, where R a =alkyl, cycloalkyl, aryl or aralkyl,

[0265] Each R' = independently hydrogen, alkyl or cycloalkyl, the carbon chain may be replaced by non-adjacent oxygen, sulfur or NR a The group is interrupted, preferably wherein each R'=ethyl and / or methyl,

[0266] each X, X' = independently of one another a linear and / or branched alkylene or cycloalkylene radical having 1 to 20 carbon atoms, preferably wherein each X, X' = an alkylene radical having 1 to 4 carbon atoms,

[0267] Each R" = independently alkyl, cycloalkyl, aryl or aralkyl, the carbon chain may be replaced by non-adjacent oxygen, sulfur or NR a The radical is interrupted, preferably where each R"=alkyl, more particularly having 1 to 6 C atoms,

[0268] n=parameter 0 to 2, m=parameter 0 to 2, m+n=2, and x, y=parameter 0 to 2.

[0269] The corresponding preferred alkoxy groups (OR') may be identical or different, but what is decisive for the structure of these groups is the extent to which they influence the reactivity of the hydrolyzable silane groups. Preferably R' is an alkyl group, more particularly having 1 to 6 carbon atoms. Particularly preferred are groups R' which increase the reactivity of the silane groups, i.e. represent good leaving groups. Therefore, methoxy groups are preferred relative to ethoxy groups, which in turn are preferred relative to propoxy groups. Therefore, it is particularly preferred that R'=ethyl and / or methyl, more particularly methyl. In addition, the reactivity of the organofunctional silanes may also be significantly affected by the length of the spacer X, X' between the silane functional group and the organofunctional group for reacting with the component to be modified. Examples that can be mentioned include "α" silanes, which are available from Wacker and in which there is a methylene group between the Si atom and the functional group instead of the propylene group present in the case of "γ" silanes.

[0270] In component e2), preferably between 10 and 80 mol %, preferably between 15 and 70 mol %, more preferably between 20 and 50 mol % and even more preferably between 25 and 40 mol % of the isocyanate groups initially present have reacted with at least one organosilane, preferably to form structural units (I) and / or (II), more preferably to form structural units (I) and (II).

[0271] Furthermore, preference is given to components e2) in which the total amount of structural units (I) is between 3 and 90 mol-%, more preferably between 5 and 70 mol-%, in each case based on the total amount of structural units (I) plus (II), and the total amount of structural units (II) is between 97 and 10 mol-%, more preferably between 95 and 30 mol-%, in each case based on the total amount of structural units (I) plus (II).

[0272] At least one organic component e2) having on average two or more NCO groups, which before the reaction with the at least one silane serves as the parent structure of the component e2), before the reaction with the at least one silane, represents at this stage a di- and / or polyisocyanate. Preferably, the at least one di- and / or polyisocyanate is an aromatic, aliphatic, alicyclic and / or heterocyclic di- and / or polyisocyanate, in particular aliphatic and acyclic.

[0273] At least one organic component e2) preferably has a cycloaliphatic parent structure and / or a parent structure derived from a cycloaliphatic polyisocyanate by trimerization, dimerization, urethane formation, biuret formation, uretdione formation and / or allophanate formation, wherein component e2) has at least one structural unit of formula (I) and / or (II). Alternatively or additionally, at least one organic component 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, wherein component e2) has at least one structural unit of formula (I) and / or (II).

[0274] Most preferably, at least one organic component 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, wherein component e2) has at least one structural unit of formula (I) and / or (II). Trimers, i.e. isocyanurates, are particularly preferred.

[0275] The acyclic aliphatic polyisocyanates serving as parent structures are preferably substituted or unsubstituted aliphatic polyisocyanates known per se. Examples are 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.

[0276] In addition, preferred polyisocyanate matrix structures are polyisocyanates derived from this acyclic aliphatic polyisocyanate by trimerization, dimerization, carbamate formation, biuret formation, uretdione formation and / or allophanate formation, more particularly biuret dimer and / or allophanate dimer and / or isocyanurate trimer. The polyisocyanate matrix structure can also be a polyisocyanate prepolymer with carbamate structural units, which is obtained by the reaction of polyols with stoichiometric excess of the above-mentioned acyclic aliphatic polyisocyanates. This polyisocyanate prepolymer is described in, for example, US-A-4,598,131. Particularly preferred polyisocyanate matrix structures are hexamethylene diisocyanate and / or its biuret dimer and / or allophanate dimer and / or isocyanurate trimer and / or its uretdione, and also a mixture of the polyisocyanate matrix structures. Particularly preferred polyisocyanate precursors are hexamethylene diisocyanate and / or its isocyanurate trimer, optionally together with its uretdione.

[0277] The cycloaliphatic polyisocyanates used as parent structures are preferably substituted or unsubstituted cycloaliphatic polyisocyanates known per se. Examples of preferred polyisocyanates are isophorone diisocyanate, cyclobutane 1,3-diisocyanate, cyclohexane 1,3-diisocyanate, cyclohexane 1,4-diisocyanate, methylcyclohexyl diisocyanate, hexahydrotoluene 2,4-diisocyanate, hexahydrotoluene 2,6-diisocyanate, hexahydrophenylene 1,3-diisocyanate, hexahydrophenylene 1,4-diisocyanate, perhydrodiphenylmethane 2,4′-diisocyanate, 4,4′-methylenedicyclohexyl diisocyanate (e.g., Benzene 2,4′-diisocyanate from Bayer AG), cyclohexane 1,3-diisocyanate, cyclohexane 1,4-diisocyanate, cyclohexane 2,4′ ... W) and a mixture of the above-mentioned polyisocyanates. In addition, preferred polyisocyanate matrix structures are polyisocyanates derived from this alicyclic polyisocyanate by trimerization, dimerization, carbamate formation, biuret formation, uretdione formation and / or allophanate formation, more particularly biuret dimer and / or allophanate dimer and / or isocyanurate trimer. The polyisocyanate matrix structure can be a polyisocyanate prepolymer with carbamate structural units, which is obtained by the reaction of polyols with stoichiometric excess of the above-mentioned alicyclic polyisocyanates. This polyisocyanate prepolymer is described in, for example, US-A-4,598,131. Particularly preferred alicyclic polyisocyanates are isophorone diisocyanate and 4,4'-methylene dicyclohexyl diisocyanate and / or its biuret dimer and / or its allophanate dimer and / or its isocyanurate trimer.

[0278] The at least one silane for reaction with the at least one organic component e2) carrying on average two or more NCO groups, before e2) is incorporated into component E), is preferably

[0279] At least one compound having formula (Ia)

[0280] H-NR-(X-SiR” x (OR') 3-x ) (Ia),

[0281] and / or at least one compound having formula (IIa)

[0282] HN(X-SiR” x (OR') 3-x ) n (X'-SiR" y (OR') 3-y ) m (IIa),

[0283] wherein the substituents have the definitions given above, including the preferred definitions.

[0284] Preferred compounds (Ia) are aminoalkyltrialkoxysilanes, such as 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. Aminosilanes of this type are available, for example, from Degussa under the trade name or from OSI Corporation under the trade name Available.

[0285] 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. Aminosilanes of these types are available, for example, from Degussa under the trade name or from OSI Corporation under the trade name Available.

[0286] Optional Ingredients e3)

[0287] The optionally present component e3) is an organic component which, unlike e2), carries on average two or more NCO groups. In particular, the optionally present component e3) does not contain any silane-modified NCO groups.

[0288] The optionally present component e3) can be identical to or different from the component b2). Preferably, the component e3) carries on average more than two NCO groups.

[0289] 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. The trimers of IPDI (isophorone diisocyanate) and / or HDI (hexamethylene diisocyanate), i.e. isocyanurates, are particularly preferred.

[0290] 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 above-mentioned polyisocyanates. Suitable polyisocyanate parent structures can be polyisocyanate prepolymers with urethane structural units, which are obtained by the reaction of polyols with stoichiometric excess of the above-mentioned aliphatic polyisocyanates. Particularly preferred polyisocyanate parent structures are hexamethylene diisocyanate and / or its biuret dimer and / or allophanate dimer and / or isocyanurate trimer and / or its uretdione, as well as mixtures of the polyisocyanate parent structures. Particularly preferred polyisocyanate parent structures are hexamethylene diisocyanate and / or its isocyanurate trimer, optionally with its uretdione.

[0291] Suitable cycloaliphatic polyisocyanates are preferably substituted or unsubstituted cycloaliphatic 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 abovementioned polyisocyanates. Suitable polyisocyanate parent structures can be polyisocyanates derived from alicyclic polyisocyanates by trimerization, dimerization, carbamate formation, biuret formation, uretdione formation and / or allophanate formation, more particularly biuret dimer and / or allophanate dimer and / or isocyanurate trimer. The polyisocyanate parent structure can be a polyisocyanate prepolymer with carbamate structural units, which is obtained by the reaction of polyols with a stoichiometric excess of the above-mentioned alicyclic polyisocyanates. Particularly preferred alicyclic polyisocyanates are isophorone diisocyanate and 4,4'-methylene dicyclohexyl diisocyanate and / or its biuret dimer and / or its allophanate dimer and / or its isocyanurate trimer.

[0292] Optional component F)

[0293] Optional component F) is a reducing agent component and comprises at least one organic solvent f1). Component F) is used to dilute the coating composition to be prepared and for this reason comprises at least one organic solvent f1) and preferably consists of at least one organic solvent f1). Examples of such organic solvents include those mentioned above with respect to components a1) and b1) and c1) and d1) and e1). Component F) may comprise more than one organic solvent f1). At least one organic solvent f1) may be the same or different from at least one organic solvent a1) and / or b1) and / or c1) and / or d1) and / or e1). If more than one organic solvent is used as a1) and / or b1) and / or c1) and / or d1) and / or e1) and / or f1), then a1) and / or b1) and / or c1) and / or d1) and / or e1) and / or f1) may be partly the same and partly different.

[0294] Multi-layer coating system

[0295] Another subject of the present invention is a multilayer coating system present on an optionally precoated substrate, preferably obtainable by the process for producing a multilayer coating system, and comprising at least three coating layers L1, L2 and L3 which are different from one another and are preferably positioned adjacent to one another, namely

[0296] a first coating L1 applied on at least a portion of the optionally precoated substrate, said layer L1 being obtainable from a primer coating composition according to the invention,

[0297] a second coating L2 applied on the first coating L1, and

[0298] A third coating L3 is applied on the second coating L2, wherein the third coating L3 is preferably the outermost coating of the multi-layer coating system.

[0299] All preferred embodiments described above in conjunction with the primer coating system, the primer coating composition, the abovementioned uses and methods and the coated substrates and the method for producing the multilayer coating system and in each case preferred embodiments thereof are also preferred embodiments of the multilayer coating system itself.

[0300] Preferably, the multi-layer coating system is obtained by the above-mentioned method for preparing a multi-layer coating system.

[0301] method

[0302] 1. Humidity exposure

[0303] Humidity exposure was determined according to the high humidity test (96 h) according to GMW 14729 (4th edition, August 2020).

[0304] 2. Water vapor permeability

[0305] The water vapor permeability is determined according to ASTM D1653 (2021) according to test method A (dry cup method). The test is carried out at 38°C and 90% RH (relative humidity). The weight change is determined by the difference between the initial weight and the weight at different times during and after the test.

[0306] 3. Moisture absorption rate

[0307] The moisture absorption (water uptake) was determined by weight change studies. The weight change of the coated panels was determined by the difference between the initial coated panel weight and the weight after humidity exposure and subsequent storage of the coated panels for 5 days and optionally again for 6 months under ambient conditions after said exposure.

[0308] 4. Dynamic Light Scattering (DLS)

[0309] According to ISO21501-4 standard by dynamic light scattering (DLS) method The average particle size of component a3) (and the silica starting material used) was determined. The Beckman Coulter instrument (model: Delsa Nano C particle analyzer; software: Delsa Nano2.31). Before the inspection, prepare about 0.01% sample solution.

[0310] 5. Non-volatile fraction

[0311] The non-volatile fraction (solid fraction, solids content) is determined in accordance with DIN EN ISO 3251:2018-07 at 140° C. for 60 min.

[0312] 6. Glass transition temperature

[0313] The glass transition temperature is measured by DSC measurement in accordance with DIN EN ISO 11357-2 (2019-03).

[0314] Examples

[0315] The following examples further illustrate the present invention but should not be construed as limiting its scope. 'Pbw' means parts by weight. If not otherwise defined, 'parts' means 'parts by weight'.

[0316] 1. Preparation of 2K primer coating systems and coating material compositions obtainable therefrom

[0317] 1.1 The “A” components of the 2K primer coating system IPC1 (invention) and the 2K primer coating systems CPC1 (comparative) and CPC2 (comparative) were prepared by mixing the ingredients listed in Table 1.1 in this order.

[0318] Table 1.1: IPC1 and the “A” components of CPC1 and CPC2

[0319]

[0320]

[0321] Pigment paste P1 contains 60 wt.-% of titanium dioxide pigment and further comprises an alkyl resin. Pigment paste P2 contains 6 wt.-% of carbon black pigment and further comprises an alkyl resin. Pigment paste P3 contains 10 wt.-% of organic blue pigment and further comprises an alkyl resin. Pigment paste P4 contains 47 wt.-% of inorganic yellow pigment and further comprises an alkyl resin. 4167 is a commercially available amine neutralized phosphate catalyst. TIB 216 is a liquid tin catalyst based on dioctyltin compounds. BYK 3565 is a commercially available surfactant additive. AS1 and AS2 are both commercially available aromatic solvent mixtures, which differ from each other. NMP is N-methylpyrrolidone. CPO is a commercially available chlorinated polyolefin solution (solids content 19.8 wt.-%). ACL is CL-408, a commercially available solvent-based chlorinated polypropylene modified with an acrylic resin, which is OH-functional (solids content 44.0 to 46 wt.-%). The epoxy resin is the reaction product of bisphenol A and DGEBA, bisphenol A diglycidyl ether, and has an epoxy equivalent weight of 465 to 500.

[0322] The silica-silane condensate used was MTMS-silica condensate and was prepared by reacting methyltrimethoxysilane (MTMS) with a commercially available nanosilica dispersion ( To prepare the silica-silane condensate, MTMS (0.45 mol) was mixed with acetic acid (1.45 wt.-%) and the mixture was cooled to 0° C. Then, water (9.7 wt.-%, 0.54 mol) and AS-40 (24.5 wt.-%, 0.97 mol, of which 0.16 mol thereof corresponded to silica and the remainder to water also present in this product). The molar ratio of MTMS to silica was therefore 0.45:0.16, i.e. about 2.8:1. The resulting mixture was then stirred at room temperature for 12 to 16 h. Acetic acid and TBAA (tetrabutylammonium acetate) were then added as catalysts (3.13 wt.-% acetic acid and 0.17 wt.-% TBAA), and the mixture was stirred for 2 to 3 h, keeping the pH at 5.1. The resulting mixture (solids content 43 wt.-%) was then diluted with isopropanol (1:1 by weight) and then used in this form as silica-silane condensate for the preparation of the "A" component of IPC1.

[0323] 1.2 The "B" component for the 2K primer coating systems IPC1, CPC1 and CPC2 is prepared by mixing the ingredients listed in Table 1.2 in this order.

[0324] Table 1.2: IPC1 and the "B" components of CPC1 and CPC2

[0325]

[0326] N3600 is a commercially available aliphatic polyisocyanate (HDI trimer). 1189 is N-(3-(trimethoxysilyl)propyl)butylamine. 1124 is bis(trimethoxysilylpropyl)amine.

[0327] 1.3 Primer coating material compositions were prepared by mixing the "A"-component and the "B"-component of the primer coating systems IPC1 as well as CPC1 and CPC2, respectively.

[0328] To prepare a composition obtainable from IPC1, the "A" and "B" components were mixed in a weight ratio of 14.4:1 ("A" to "B") to one another. To prepare a composition obtainable from CPC1 and CPC2, the "A" and "B" components were mixed in a weight ratio of 12.9:1 ("A" to "B") to one another.

[0329] The mixing ratio is calculated and selected such that an excess of about 10 to 12 wt.-% of polyisocyanate from component "B" is still present in the resulting composition, so that when applied on top of the primer coating film, the subsequently applied basecoat film also cures by NCO migration, which is obtained by applying the primer coating material composition to the surface of the substrate.

[0330] 2. Preparation of 2K clearcoat systems and clearcoat material compositions obtainable therefrom

[0331] 2.1 The "A"-component of the 2K clearcoat system ICC1 was prepared by mixing the ingredients listed in Table 2.1 in this order.

[0332] Table 2.1: “A”-components of ICC1

[0333]

[0334]

[0335] Catalyst 1 is a commercially available catalyst, namely TIB 216 (DOTL), which is 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. 4167 has been described above. AS3 is a commercially available aromatic solvent mixture that is different from AS1 and AS2 identified above. Acrylic Resin 1 is a 2-hydroxyethyl acrylate having a T of -15°C prepared from n-butyl methacrylate, styrene, 4-hydroxybutyl acrylate and 2-hydroxyethyl acrylate. g A solution of an OH-functional (meth) acrylic resin (solid content: 65 wt %). Acrylic resin 2 is prepared from 3-hydroxypropyl methacrylate, 2-ethylhexyl (meth)acrylate and cyclohexyl (meth)acrylate and has a T of +34°C. g Dispersion of an OH-functional (meth)acrylic resin (solids content: 67.5 wt.-%). Acrylic resin 3 is prepared from n-butyl methacrylate, styrene, cyclohexyl methacrylate, 2-hydroxypropyl methacrylate and 2-hydroxyethyl methacrylate and has a T of +46°C. g Dispersion of an OH-functional (meth)acrylic resin of (solids content: 60.0 wt.-%).

[0336] 2.2 The "B" component of the 2K clearcoat system ICC1 is a polyisocyanate. The polyisocyanate (product N3600 as starting material) before its use / as component "B" by using two different organosilanes (i.e. 1189 and 1124) silanization. N3600 is a commercially available aliphatic polyisocyanate (HDI trimer). 1189 is N-(3-(trimethoxysilyl)propyl)butylamine. 1124 is bis(trimethoxysilylpropyl)amine. The "B" component of ICC1 is commercially available ( "B" component of the repair paint).

[0337] 2.3 Clearcoat Material The composition was prepared by mixing the "A" component and the "B" component of the clearcoat system ICC1 in a weight ratio of 1:1 ("A" to "B") to each other.

[0338] 3. Properties of primer coating films and layers obtained from primer coating material compositions

[0339] 3.1 Water vapor permeability

[0340] The self-supporting primer coating films were sprayed with primer composition IPC1 or CPC1 respectively on the After flashing at room temperature for 10 minutes, the two films were baked in an oven at 50°C for 30 minutes to obtain a dry film with a thickness of 0.5 mil (12.7 μm). Then, the self-supporting primer coating film was carefully removed from the Remove from membrane.

[0341] The water vapor permeability of the self-supporting primer film was measured according to the method disclosed above. The results are shown in Figure 1 The figure shows the water vapor permeability of a self-supporting control primer film (a primer film obtained from a composition which in turn was obtained from a comparative primer coating system CPC1) versus a primer film of the invention containing about 9 wt.-% of a silica-silane condensate, based on the total weight of the primer composition IPC1 before application (a primer film obtained from a composition which in turn was obtained from a primer coating system IPC1 of the invention). Figure 1 As shown, a significant difference in water vapor permeability is observed: the permeability of the film obtained with IPC 1 is about 35% lower than that of the control film obtained with CPC 1. Thus, in the absence of silica-silane condensates, poorer moisture barrier properties are observed.

[0342] In Tables 3.1a and 3.1b, we summarize Figure 1 The corresponding data shown.

[0343] Table 3.1a: Water vapor permeability data - IPC1 membrane

[0344]

[0345]

[0346] Table 3.1b: Water vapor permeability data - CPC1 membrane

[0347]

[0348] 3.2 Moisture absorption after humidity exposure and storage

[0349] Carbon fiber (C-fiber) reinforced plastic substrate is used as substrate, i.e. product XA3418, which is a carbon fiber reinforced polyamide. The primer coating material composition obtained from the primer coating system IPC1 or CPC1 or CPC2 prepared as described in Item 1.3 is applied to the surface of the substrate to form a primer film and flashed for 10 minutes at ambient conditions (room temperature). A commercially available colored solvent-based base coating material composition (Hot Pepper Red) is then sprayed onto the primer film to form a base coating film and flashed for 10 minutes at ambient conditions (room temperature). Then, a clear coating material composition obtained from the clear coating system ICC1 prepared as described in Item 2.3 is applied to the base coating film and flashed for 10 minutes at ambient conditions (room temperature), and then all films are baked simultaneously at a substrate temperature of 122°F (50°C) for 30 minutes.

[0350] The dry film thickness of each primer layer obtained after curing each primer film is 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 each basecoat layer film is 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 each clearcoat layer film is in the range of 1.9 to 2.1 mil (48.26 μm to 53.34 μm).

[0351] The moisture absorption was measured according to the method disclosed above. The effect of humidity on the coated PA-CF (carbon fiber reinforced polyamide) substrate was studied by exposing the coated samples (PA-CF substrates) (which were coated with all three layers (i.e., primer / base coat / clear coat)) to a humidity chamber according to the test method mentioned in the 'methods' section. The water absorption was determined 5 days and 6 months after the humidity test was performed (during which the coated substrates were stored under ambient conditions at room temperature). All coated substrates had similar coatings except for the primer, which was prepared by using the primer coating system IPC1 or CPC1 or CPC2. The water absorption was studied by measuring the weight increase after exposure and storage: the weight change of the coated plate was determined by the difference between the initial coated plate weight and the weight after humidity exposure (after 5 days of equilibrium and after 6 months).

[0352] Significantly less moisture absorption (water absorption) (about 38 to 40 wt.%) was observed for substrates coated with multiple coatings comprising primer films of the invention (primer films obtained from compositions which in turn were obtained from comparative primer coating systems CPC1 or CPC2) than for substrates coated with multiple coatings comprising control primers (primer films obtained from compositions which in turn were obtained from comparative primer coating systems CPC1 or CPC2), as shown in Table 3.2. In Table 3.2, uncoated panels were also investigated as additional control substrates.

[0353] Table 3.2: Moisture absorption effect of uncoated and coated panels

[0354]

[0355] nd = not determined.

Claims

1. A primer coating system comprising at least two components A) and B) and optionally at least one further component C), which are different from one another and are separated from one another, The component A) comprises at least components a2) and a3) and optionally at least one component a1), which are different from one another, namely optionally at least one organic solvent a1), at least one polymer a2) which contains functional groups reactive toward NCO groups, and at least one condensation product a3) obtainable at least by reaction of (i) at least one organosilane carrying at least one hydrolyzable group with (ii) at least one silicon dioxide, wherein the at least one organosilane and the at least one silicon dioxide are used in a molar ratio to one another in the range from 10:1 to 1:1, wherein component B) comprises at least component b2) and optionally at least one component b1), which are different from one another, namely optionally at least one organic solvent b1), and at least one organic component b2) which carries on average two or more NCO groups, and The optional component C) is a reducing agent component and comprises at least one organic solvent c1).

2. The primer coating system according to claim 1, wherein: The at least one condensation product a3) is present in component A) in an amount within the range of 1.0 to 25.0 wt.-%, preferably 2.0 to 20.0 wt.-%, more preferably 3.0 to 17.5 wt.-%, yet more preferably 4.0 to 15.0 wt.-%, still more preferably 5.0 to 14.0 wt.-%, even more preferably 6.0 to 13.0 wt.-%, most preferably 7.0 to 12.0 wt.-%, in each case based on the total weight of component A).

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

4. Primer coating system according to one or more of the preceding claims, wherein: The molar ratio of the at least one organosilane and the at least one silicon dioxide used to prepare the condensation product a3) to one another is in the range from 8:1 to 1:1, preferably from 6:1 to 1:1, more preferably from 4:1 to 1:1, still more preferably from 4:1 to 1.1:1, yet more preferably from 4:1 to 1.5:1, most preferably from 4:1 to 2:

1.

5. Primer coating system according to one or more of the preceding claims, wherein: The condensation reaction of the at least one organosilane carrying at least one hydrolyzable group with the at least one silicon dioxide takes place in an aqueous medium and is preferably catalyzed by at least one preferably organic acid.

6. Primer coating system according to one or more of the preceding claims, wherein: Component A) further comprises at least one catalyst a4) which is suitable for the crosslinking of Si-containing functional groups, in particular such groups present in the condensation products a3) of component A), the at least one catalyst a4) being different from any of the components a1) to a3), preferably in an amount in the range of 0.01 to 2.5 wt.-%, more preferably 0.02 to 2.0 wt.-%, even more preferably 0.03 to 1.5 wt.-%, still more preferably 0.04 to 1.2 wt.-%, yet more preferably 0.05 to 1.0 wt.-%, in each case based on the total weight of component A), wherein the catalyst a4) is preferably selected from phosphorus-containing organic component, more preferably selected from acyclic phosphoric acid diesters, acyclic phosphoric acid monoesters, cyclic phosphoric acid diesters and cyclic phosphoric acid monoesters, wherein each of the above phosphoric acid diesters and monoesters may optionally be present in the form of an adduct with at least one amine, preferably at least one tertiary amine, even more preferably, wherein at least two catalysts are present as the at least one catalyst a4), these catalysts are selected from acyclic phosphoric acid diesters, acyclic phosphoric acid monoesters, cyclic phosphoric acid diesters and cyclic phosphoric acid monoesters, but wherein 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 in the form of an amine adduct, and / or, preferably as well as, At least one catalyst a5) suitable for crosslinking NCO groups, in particular constituent b2) of component B), which at least one catalyst a5) is different from any of the constituents a1) to a3) and from the catalyst a4), preferably in an amount in the range from 0.001 to 1.00 wt.-%, more preferably from 0.002 to 0.80 wt.-%, even more preferably from 0.003 to 0.60 wt.-%, still more preferably from 0.004 to 0.40 wt.-%, yet more preferably from 0.005 to 0.20 wt.-%, most preferably from 0.007 to 0.15 wt.-%, in each case based on the total weight of component A), wherein the catalyst a5) is preferably selected from organotin catalysts.

7. Primer coating system according to one or more of the preceding claims, wherein: the at least one organic component 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 the components b1) and b2) and which carries at least one hydrolyzable group and preferably also at least one non-hydrolyzable organic residue.

8. Primer coating system according to one or more of the preceding claims, wherein: Component A) comprises at least one, preferably at least two, more preferably at least three of the following components a6) to a8), which are different from each other, from each of the components a1) to a3) and from each of the components a4) and a5) defined in claim 6, namely at least one epoxy resin as constituent a6), preferably in an amount in the range from 0.5 to 15.0 wt.-%, more preferably from 1.0 to 10.0 wt.-%, even more preferably from 1.5 to 7.5 wt.-%, still more preferably from 2.0 to 5.5 wt.-%, in each case based on the total weight of component A), at least one chlorinated polyolefin as constituent a7), preferably in an amount in the range from 5.0 to 35 wt.-%, more preferably from 6.0 to 30.0 wt.-%, even more preferably from 7.0 to 25.0 wt.-%, still more preferably from 8.0 to 20 wt.-%, in each case based on the total weight of component A), and At least one pigment and / or filler as constituent a8), preferably in an amount in the range from 5.0 to 30 wt.-%, more preferably from 6.0 to 25.0 wt.-%, even more preferably from 7.0 to 20.0 wt.-%, still more preferably from 8.0 to 15 wt.-%, in each case based on the total weight of component A).

9. Primer coating system according to one or more of the preceding claims, wherein: Component A) comprises as additional component a9) at least one leveling agent and / or dispersant, which is preferably a (meth)acrylate polymer, which preferably contains at least one ether segment, more preferably in the side chain, and / or which preferably contains at least one siloxane unit, more preferably also in the side chain, wherein component a9) is preferably present in component A) in a range of 0.10 to 5.0 wt.-%, more preferably 0.50 to 4.0 wt.-%, even more preferably 0.80 to 3.5 wt.-%, in each case based on the total weight of component A).

10. A primer coating composition, It is obtainable by mixing at least components A) and B) and optionally C) of the primer coating system according to one or more of the preceding claims with one another. or It comprises at least components (i), (ii) and (iii) and optionally also (iv), which are different from each other, namely (i) optionally at least one organic solvent, which preferably corresponds to at least one organic solvent a), b1) and / or c1) as defined in claim 1, (ii) at least one film-forming polymer which is self-crosslinking or externally crosslinking, preferably externally crosslinking, more preferably which corresponds to the at least one polymer a2) containing functional groups reactive toward NCO groups as defined in claim 1, (iii) at least one condensation product corresponding to the condensation product a3) as defined in one or more of claims 1 to 5, and (iv) at least in case the at least one film-forming polymer (ii) is an externally crosslinked polymer, optionally at least one crosslinking agent, preferably selected from blocked polyisocyanates, melamine formaldehyde resins and mixtures thereof.

11. The primer coating composition according to claim 10, wherein: It contains an excess of component b2) having on average two or more NCO groups, so that when said component migrates into the intermediate coating film, preferably into a basecoat film applied on top of a basecoat film obtained from the basecoat composition on a substrate, at least partial curing of the intermediate coating film is achieved when the intermediate coating film contains at least one preferably polymer component containing functional groups reactive toward NCO groups.

12. Use of a primer coating composition according to claim 10 or 11 for improving the water resistance and / or moisture resistance of a cured primer coating film obtainable therefrom and / or a cured multi-layer coating system containing at least one cured primer coating film, wherein the cured primer coating film is obtainable from the primer coating composition.

13. A method for coating a substrate, comprising at least step 1), namely 1) applying the primer coating composition according to claim 10 or 11 at least partially to at least one surface of an optionally pre-coated substrate and forming a primer coating film on said surface, 1a) and optionally at least one further step 1a): curing the at least one primer coating film obtained after step 1) to obtain at least one cured primer coating on said surface.

14. A coated substrate obtainable by a process according to claim 13.

15. A method for preparing a multilayer coating system on at least one surface of an optionally pre-coated substrate, the method comprising at least steps 1) to 3) and optionally 4), namely 1) applying a first coating composition at least partially to at least one surface of an optionally pre-coated substrate and forming a first coating film on said surface, wherein the first coating composition is a primer coating composition according to claim 10 or 11, and 2) applying at least one base coating 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 forming a second coating film preferably adjacent to the first coating film, and 3) applying a top coating composition, preferably a clear coating 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 forming a third coating film, which is preferably adjacent to the second coating film and is preferably the outermost coating film of the formed multi-layer coating system, and 4) optionally co-curing the first, second and third coating films to obtain a multi-layer coating system comprising cured first, second and third coatings.

16. A multilayer coating system present on an optionally pre-coated substrate, preferably obtainable by a process according to claim 15 and comprising at least three coating layers L1, L2 and L3 which are different from each other and are preferably positioned adjacent to each other, i.e. a first coating layer L1 applied on at least a portion of the optionally pre-coated substrate, said layer L1 being obtainable from a primer coating composition according to claim 10 or 11, a second coating L2 applied on the first coating L1, and A third coating L3 is applied on the second coating L2, wherein the third coating L3 is preferably the outermost coating of the multi-layer coating system.

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