Multi-layer coating system derived from block copolymer containing topcoat composition

Abstract

The present invention relates to a multilayer coating system present on a substrate and comprising at least two coating layers L1 and L2 that are different from one another, namely a first coating layer L1 applied over at least a portion of the substrate and a second topcoat layer L2 applied over the first coating layer L1, wherein the topcoat layer L2 is formed from a coating composition comprising at least one block copolymer containing a main chain and at least two blocks B1 and B2 and side chains S1 and S2 that comprise different polymer moieties M1 and M2, a method for producing said multilayer coating system, coated substrates obtainable therefrom, and the use of a coating composition comprising a block copolymer for improving, in particular increasing, the color of the multilayer coating system of the present invention.

Description

[Technical field]

[0001] The present invention relates to a multi-layer coating system present on a substrate and comprising at least two coating layers L1 and L2 which are different from one another, namely a first coating layer L1 applied on at least a part of the substrate and a second top-coat layer L2 applied on top of the first coating layer L1, wherein the top-coat layer L2 is formed from a coating composition comprising at least one block copolymer containing a main chain and at least two blocks B1 and B2 and side chains S1 and S2 comprising different polymer moieties M1 and M2, a method for producing said multi-layer coating system, coated substrates obtainable therefrom and the use of the coating composition comprising a block copolymer for improving, in particular increasing, the chromaticity of the multi-layer coating system of the present invention. [Background technology]

[0002] In a typical automotive coating process, multiple layers are generally applied to the surface of a suitable substrate, such as a metal substrate, in the form of a multilayer coating system, for example, an electrodeposition coat (e-coat) as the outermost layer, optionally a primer, one or two base coats, and a top coat, especially a clear coat, in that order. At least an e-coat layer is generally applied to the substrate surface and then cured before any of the further coatings are applied on top. Following application and curing, at least one (first) base coat formulation, usually pigmented, is then applied, followed by applying at least an electrodeposition coating film, and also optionally a primer. Often, a second base coat is applied on top of the first base coat film as a further intermediate coating film. A top coat, such as a clear coat, is then usually applied, with at least the base coat and the top coat nowadays typically being applied with the aid of a wet-on-wet application. The coated substrate is then passed through an oven in a 2C1B or 3C1B method, depending on the number of base coats, at a temperature for simultaneously curing at least the base coat and the top coat, such as a clear coat. In some cases, if present, the primer coat is also cured at this stage along with the base coat, and top coat, particularly the clear coat, for example in the 4C1B process.

[0003] There are a great number of necessary requirements that must be met and / or met by the multilayer coatings used in the automotive industry, resulting from regulations but also from quality standards set as such by the automotive industry. To meet these requirements, the multilayer coating must therefore exhibit or show, at least to a sufficient extent, several desirable properties. For example, the avoidance of optical defects is desirable. Additionally and in particular, it is desirable that excellent color properties of the multilayer coating be achieved.

[0004] A multilayer coating composed of at least two coating layers is disclosed, for example, in WO2020 / 160299A1. The first layer is a photonic crystal film containing a dye and a block copolymer. The second layer present on the first layer is used as a topcoat and is an optical adhesive or a UV-curable resin. The block copolymer is necessarily present in the first layer together with at least one dye. WO2020 / 160299A1 aims to provide a multilayer coating with good transparency in the visible spectrum. As such, a coating composition used to produce a pigmented photonic crystal film is further disclosed in WO2020 / 180427A1, but a multilayer coating is not disclosed therein, much less a multilayer coating produced via a wet-on-wet technique.

[0005] Since the multilayer coatings known in the state of the art do not always exhibit sufficiently good color properties, for example in terms of brightness, but especially in terms of chromaticity, there is a need to provide cured or dried coatings and coating systems which exhibit improved color properties and color values, especially in terms of their chromaticity, and the achievement of excellent chroma values, compared to coatings and coating systems known in the prior art. At the same time, these cured coatings and coating systems should be produced in an economically advantageous manner with a minimum number of necessary method steps, especially if these coatings and coating systems are used in automotive OEM production. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] WO2020 / 160299A1 [Patent Document 2] WO2020 / 180427A1 Summary of the Invention [Problem to be solved by the invention]

[0007] The object underlying the present invention was therefore to provide multi-layer coating systems which exhibit improved color properties and color values ​​compared to coatings and coating systems known in the prior art, in particular in terms of their chromaticity and the achievement of excellent chroma values, and at the same time can be produced in an economically advantageous manner with a minimum number of required method steps, in particular when these multi-layer coating systems are used in automotive OEM production. In particular, the object underlying the present invention was to provide a satisfactory balance between, on the one hand, the achievement of good color properties, in particular in terms of chromaticity values / high chroma values, and, on the other hand, the ability to result in a multi-layer coating system having these desired properties with as few method steps as possible. [Means for solving the problem]

[0008] This object has been solved by the subject matter of the present patent application and by the preferred embodiments thereof disclosed herein, i.e. by the subject matter described herein.

[0009] The first subject of the invention is a method for preparing a substrate comprising at least two coating layers L1 and L2, which are present on an optionally precoated substrate and which are different from one another, i.e. a first coating layer L1 applied over at least a portion of the optionally precoated substrate; and A topcoat layer as a second coating layer L2 applied over the first coating layer L1 A multi-layer coating system comprising: the topcoat layer L2 is formed from a coating composition comprising at least one block copolymer containing a main chain and at least two blocks B1 and B2 that are different from each other, block B1 comprises at least one type of side chain S1 attached to the main chain, block B2 comprises at least one type of side chain S2 attached to the main chain, different from side chain S1, each of the side chains S1 comprises at least one polymer moiety M1 selected from the group consisting of polyester, polyether and poly(meth)acrylate moieties, each of the side chains S2 comprises at least one polymer moiety M2 different from polymer moiety M1 and selected from the group consisting of polyester, poly(meth)acrylate, polyether, polysiloxane and polystyrene moieties, It is a multi-layer coating system.

[0010] A further subject of the present invention is a method for producing the multi-layer coating system of the present invention, comprising at least steps (1), (2) and (3), i.e. (1) applying a basecoat composition, preferably pigmented, to at least a portion of an optionally precoated substrate to form a first coating film on at least a portion of the optionally precoated substrate; (2) applying a topcoat composition, comprising at least one block copolymer and different from the basecoat composition applied in step (1), to the first coating film present on the substrate obtained after step (1) to form a second coating film, preferably adjacent to the first coating film, said topcoat composition being preferably a clearcoat composition; (3) curing or drying at least the second coating film applied in step (2), and optionally also the first coating film applied in step (1), if said first coating film was not cured or dried before carrying out step (2), to obtain a multi-layer coating system comprising at least a first and a second coating layer L1 and L2. The method includes:

[0011] A further subject of the invention is a coated substrate obtainable by the method according to the invention.

[0012] A further subject of the present invention is the use of a coating composition comprising at least one block copolymer used according to the invention for improving, in particular for increasing, preferably improving, the color strength of the multi-layer coating system according to the invention, in particular its C* 平均 A method for increasing the saturation value, comprising: 平均 The chroma value is the sum of the C* values ​​(chroma values ​​according to the L*C*h color model) measured at angles of 15°, 45° and 110° divided by 3, especially when the coating composition is used as a topcoat composition in step (2) of the method of the present invention, and more preferably, the C* 平均 A chroma value of at least 40, preferably at least 42, more preferably at least 45, even more preferably at least 50, still more preferably at least 55, in particular at least 60, C* 平均 This is the method to use to raise the value.

[0013] The block copolymer used in the present invention is also referred to hereinafter as copolymer BBCP.

[0014] It has been particularly surprisingly found that the multilayer coating systems of the present invention exhibit improved color properties and color values, especially when compared to coatings and coating systems known in the prior art. This applies in particular to the chromaticity and the achievement of excellent chroma values ​​of these multilayer coating systems. In this respect, it has been found that the chromaticity of the multilayer coating systems can be improved, in particular, for example, their C* 平均 It has been found that the chroma value can be increased, and the C* 平均 The chroma value is the sum of the C* values ​​(chroma values ​​according to the L*C*h color model) measured at angles of 15°, 45° and 110° divided by 3. 平均 A chroma value C* of at least 40, preferably at least 42, more preferably at least 45, even more preferably at least 50, still more preferably at least 55, in particular at least 60. 平均It has been found that due to the presence of the copolymer BBCP in the topcoat layer L2, the desired color shift observed upon curing or drying ceases.

[0015] Moreover, it has been particularly surprisingly found that the multi-layer coating system of the present invention can be produced in an economically advantageous manner with a minimum number of necessary method steps, especially when these multi-layer coating systems are used in automobile OEM production.In particular, it has been found that even when copolymer BBCP is incorporated into the coating composition used to provide the topcoat layer L2 of the multi-layer coating, the above-mentioned improved color properties and color values ​​can be achieved, and good chroma values ​​are still achieved without any need to apply an additional coating layer on top that does not contain any copolymer BBCP.Therefore, the multi-layer coating system of the present invention can be provided without any additional step of applying a conventional clear coat (that does not contain copolymer BBCP).

[0016] It has been found particularly surprisingly that the aforementioned advantageous effects are the result of the incorporation of the block copolymer BBCP into the coating composition and the use of said coating composition as a topcoat composition when producing the multilayer coating system of the invention.In particular, it has been found surprisingly that the multilayer coating system of the invention can be provided with a satisfactory balance between achieving good color properties, in particular in terms of chromaticity values / high chroma values, on the one hand, and being able to provide these desired properties, on the other hand, in as few process steps as possible, without the need to apply a conventional topcoat, such as a conventional clearcoat, in particular as an outermost coat. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] The term "comprise" in the sense of the present invention, for example in the method of the present invention or in the context of the coating composition used to produce the multilayer coating system of the present invention, preferably has the meaning of "consisting of". In terms of a topcoat composition for example, in addition to all the essential components present therein, it is possible that one or more further components, which are specified hereafter in this specification and which are optionally included therein, are also included therein. All components may be present in each case in their preferred embodiments specified below.

[0018] The percentages and amounts in wt.-% (mass%) of any of the components indicated hereinafter present in each of the coating compositions add up to 100 wt.-% in each case, relative to the total mass of the respective composition.

[0019] Each of the coating compositions used in steps (1) and (2) and / or used to produce the coating layers L1 and L2 may contain, in addition to the components outlined in more detail hereafter, one or more commonly used additives depending on the desired application.For example, each of the coating compositions may contain, independently of each other, at least one additive selected from the group consisting of reactive diluents, catalysts, light stabilizers, antioxidants, degassing agents, emulsifiers, slip additives, polymerization inhibitors, plasticizers, initiators for free radical polymerization, adhesion promoters, flow control agents, film-forming aids, sag control agents (SCAs), flame retardants, corrosion inhibitors, drying agents, thickeners, biocides and / or matting agents.They may be used in known and customary proportions. Preferably, their content relative to the total mass of each coating composition is 0.01 to 20.0 wt.-%, more preferably 0.05 to 15.0 wt.-%, particularly preferably 0.1 to 10.0 wt.-%, most preferably 0.1 to 7.5 wt.-%, in particular 0.1 to 5.0 wt.-%, most preferably 0.1 to 2.5 wt.-%.

[0020] Each of the coating compositions used in the process of the present invention, particularly in each of steps (1) and (2), and / or in producing the multi-layer coating system of the present invention, can be aqueous (water-based) or organic solvent-based (solvent-based, non-aqueous).

[0021] The term "solvent-based" or "non-aqueous" is preferably understood for the purposes of the present invention to mean that an organic solvent is present as a solvent and / or diluent in the respective coating composition, if the respective coating composition is solvent-based, e.g. as the main constituent of all solvents and / or diluents present in the topcoat composition applied in step (2) of the method of the present invention. Preferably, the organic solvent is present in an amount of at least 35 wt.-%, relative to the total weight of the coating composition. Solvent-based coating compositions preferably comprise an organic solvent fraction of at least 40 wt.-%, more preferably at least 45 wt.-%, very preferably at least 50 wt.-%, in each case relative to the total weight of the coating composition. All conventional organic solvents known to those skilled in the art can be used as organic solvents. The term "organic solvent" is known to those skilled in the art, in particular from Council Directive 1999 / 13 / EC of 11 March 1999. Examples of such organic solvents may include heterocyclic, aliphatic or aromatic hydrocarbons, mono- or polyhydric alcohols, especially methanol and / or ethanol, ethers, esters, ketones and amides, such as N-methylpyrrolidone, N-ethylpyrrolidone, dimethylformamide, toluene, xylene, butanol, ethyl glycol and butyl glycol and also their acetates, butyl diglycol, diethylene glycol dimethyl ether, cyclohexanone, methyl ethyl ketone, methyl isobutyl ketone, acetone, isophorone, or mixtures thereof. The solvent-based coating composition is preferably free or essentially free of water. The term "essentially" in this context preferably means that water is not intentionally added when producing the coating composition.

[0022] The term "water-based" or "aqueous" is preferably understood for the purposes of the present invention to mean that water is present as the main constituent of all solvents and / or diluents present in the aqueous coating composition, for example the first basecoat composition applied in step (1) of the method of the present invention. Preferably, water is present in an amount of at least 35 wt.-%, relative to the total mass of the coating composition. The aqueous coating composition preferably comprises a water fraction of at least 40 wt.-%, more preferably at least 45 wt.-%, very preferably at least 50 wt.-%, in each case relative to the total mass of the coating composition. The fraction of organic solvents is preferably in the range of <20 wt.-%, more preferably in the range of 0 to <20 wt.-%, very preferably in the range of 0.5 to 20 wt.-%, or in the range of ~17.5 wt.-%, or in the range of ~15 wt.-%, or in the range of ~10 wt.-%, in each case relative to the total mass of the coating composition.

[0023] Multi-layer coating system of the present invention The multi-layer coating system of the present invention comprises at least two coating layers L1 and L2, which are different from each other and are present on an optionally pre-coated substrate.

[0024] Preferably, the first and second coating layers L1 and L2 are located adjacent to each other.

[0025] Preferably, the multi-layer coating system has a C*, preferably after curing or drying, of at least 40, more preferably at least 42, even more preferably at least 45, still more preferably at least 50, even more preferably at least 55, especially at least 60. 平均 This C* 平均 The value is the sum of the C* values ​​(chroma values ​​according to the L*C*h color model) measured at angles of 15°, 45° and 110° divided by 3. The method for measuring the chroma values ​​is described later in this specification in the "Methods" section.

[0026] Preferably, the multi-layer coating system can be obtained by a process in which at least the applied coating composition comprising at least one block copolymer BBCP used to prepare the top-coat layer L2 is cured or dried to obtain the top-coat layer L2 of the multi-layer coating system.

[0027] Curing is preferably selected from chemical curing, such as chemical crosslinking, and radiation curing, in each case at room temperature or at elevated temperature, more preferably from chemical curing, such as chemical crosslinking, in each case at room temperature or at elevated temperature. Drying preferably means physical drying (non-chemical curing) at room temperature or at elevated temperature.

[0028] substrate The multi-layer coating system of the present invention is particularly suitable as a coating for automotive bodies or parts thereof, including not only respective metal substrates but also plastic substrates, such as polymeric substrates. As a result, the preferred substrate is an automotive body or part thereof.

[0029] Suitable as the metal substrate used according to the present invention are all substrates that are commonly used and known to those skilled in the art.The substrate used according to the present invention is preferably a metal substrate, more preferably a metal substrate selected from the group consisting of steel, preferably untreated steel, cold rolled steel (CRS), hot rolled steel, galvanized steel, such as hot-dip galvanized steel (HDG), alloy galvanized steel (such as galvalume, alloy hot-dip galvanized, or galfan, etc.) and aluminized steel, aluminum and magnesium, and also Zn / Mg alloy and Zn / Ni alloy.A particularly suitable substrate is a part or complete body of an automobile for production.

[0030] Preferably, thermoplastic polymers are used as plastic substrate.Suitable polymers are poly(meth)acrylates, including polymethyl(meth)acrylates, polybutyl(meth)acrylates, polyethylene terephthalate, polybutylene terephthalate, polyvinylidene fluoride, polyvinyl chloride, polyesters, including polycarbonates and polyvinyl acetates, polyamides, polyolefins, such as polyethylene, polypropylene, polystyrene, and also polybutadiene, polyacrylonitrile, polyacetal, polyacrylonitrile-ethylene-propylene-diene-styrene copolymers (A-EPDM), ASA (acrylonitrile-styrene-acrylic ester copolymers) and ABS (acrylonitrile-butadiene-styrene copolymers), polyetherimides, phenolic resins, urea resins, melamine resins, alkyd resins, epoxy resins, polyurethanes, including TPUs, polyether ketones, polyphenylene sulfides, polyethers, polyvinyl alcohols, and mixtures thereof. Polycarbonates and poly(meth)acrylates are particularly preferred.

[0031] The substrates used according to the invention are preferably metal substrates pretreated with at least one metal phosphate, such as zinc phosphate, and / or with at least one oxalate. This type of pretreatment by phosphating, usually carried out after the substrate has been cleaned and before it is electrocoated, is a pretreatment step which is customary, especially in the automotive industry.

[0032] As outlined above, the substrate used may be a precoated substrate, i.e. a substrate having at least one cured coating film. The substrate may be precoated with a cured electrodeposition coating layer. The substrate may, for example, additionally or alternatively be provided with at least one cured or uncured primer coating film as at least one additional precoat. The term "primer" is known to those skilled in the art. The primer is typically applied after the substrate has been provided with a cured electrodeposition coating layer. If a cured primer coating film is present, the cured electrodeposition coating film is present underneath and preferably adjacent to the cured primer coating film. Curing this primer may be carried out at a temperature in the range of 40-140°C, and may in particular include a "low bake" step at a temperature in the range of 80-100°C. As outlined above, substrates provided with an uncured primer coating film may be used, in particular substrates such as metal substrates having a cured electrodeposition coating film on which said uncured primer coating film is present. Thus, the primer composition may be applied to an optionally precoated substrate to form a primer coating film on the optionally precoated substrate. An optional curing step of this primer coating film is then possible. The coating composition used to form the first coating layer L1 may then be subsequently applied before or after the curing of said primer coating film has taken place, optionally and preferably after a flashing-off period, for example a flashing-off period of 1 to 20 minutes, at a temperature preferably not exceeding 40°C, for example in the range of 18 to 30°C.

[0033] Coating layer L1 and the coating composition used to form said layer The first coating layer L1 is preferably pigmented and is applied over at least a portion of the optionally precoated substrate, such that the first coating layer L1 is present on at least a portion of the surface of the optionally precoated substrate.

[0034] Preferably, the first pigmented coating layer L1 is capable of absorbing at least those wavelengths that are not reflected by the second layer L2.

[0035] The first coating layer L1 is preferably a pigmented coating layer, and more preferably is formed from a pigmented coating composition, also referred to herein as the basecoat composition, which is the composition used in step (1) of the method of the present invention.

[0036] The basecoat composition is preferably an aqueous, i.e. water-based, coating composition or a solvent-based basecoat composition. In particular, it is a solvent-based basecoat composition. The basecoat composition may be a 1K- (one-component) composition or a 2K- (two-component) composition. Preferably, it is a 1K-composition.

[0037] The term "base coat" is known in the art and is defined, for example, in Roempp Lexikon, paints and printing inks, Georg Thieme Verlag, 1998, 10th edition, page 57. Thus, base coats are used in particular in automotive painting and in general industrial paint coloring to impart color and / or optical effects by using the base coat as an intermediate coating composition.

[0038] Preferably, the pigmented basecoat composition comprises at least one white, black and / or colored pigment, more preferably at least one black pigment, in particular at least one inorganic and / or organic black pigment.

[0039] The term "pigments" is known to the skilled artisan, for example from DIN 55943 (date: October 2001). "Pigments" in the sense of the present invention preferably refer to components in powder or flake form, which are substantially, preferably completely, insoluble in the medium surrounding them, for example in one of the coating compositions used in the present invention. Pigments are preferably colorants and / or substances that can be used as pigments due to their magnetic, electric and / or electromagnetic properties. Pigments preferably differ from "fillers" in their refractive index, the refractive index for pigments being ≧1.7. The term "fillers" is known to the skilled artisan, for example from DIN 55943 (date: October 2001). Pigments may be inorganic or organic. Black pigments, especially organic and / or inorganic black pigments, are preferred.

[0040] When at least one organic black pigment is present in the first base coat composition, it is preferably an organic black pigment, more preferably at least one IR-transmitting organic black pigment, in particular at least one perylene and / or azomethine pigment. Most preferred are black pigments No. 31 and No. 32 (PB31 and PB32) as organic black pigments. When at least one inorganic black pigment is present in the first base coat composition, it is preferably at least one carbon black pigment.

[0041] An aqueous or non-aqueous pigment paste containing at least one pigment is preferably used to prepare the basecoat composition, depending on whether the basecoat composition is solvent-based or water-based, if the basecoat composition contains at least one pigment.

[0042] Preferably, the at least one pigment present in the base coat composition, if present, is contained therein in an amount within the range of 5 to 30 wt.-%, more preferably 6.0 to 25.0 wt.-%, even more preferably 7.5 to 20 wt.-% and in particular 8.0 to 16 wt.-%, in each case relative to the total solids content of the base coat composition.

[0043] Preferably, the total solids content of the base coat composition is in the range of 10 to 65 wt.-%, more preferably 15 to 60 wt.-%, even more preferably 20 to 50 wt.-%, in particular 25 to 45 wt.-%, in each case based on the total mass of the base coat composition. Methods for determining the solids content (non-volatile content) are described in the "Methods" section hereinafter.

[0044] The basecoat composition preferably comprises, besides at least one organic black pigment, at least one binder, more preferably at least one polymer (a1) as binder.

[0045] For the purposes of the present invention, the term "binder" is understood to be the non-volatile component of the coating composition that governs film formation according to DIN EN ISO 4618 (German edition, date: March 2007). The term includes crosslinkers and additives when they represent non-volatile components. The pigments and / or fillers contained therein are therefore not included in the term "binder". Preferably, at least one polymer (a1) is the main binder of the coating composition. As the main binder in the present invention, the binder component preferably refers to the one that is present in a higher proportion, relative to the total weight of the coating composition, when no other binder components are present in the coating composition.

[0046] The term "polymer" is known to those skilled in the art and for the purposes of the present invention includes polyaddition and polymerization products, as well as polycondensation products. The term "polymer" includes both homopolymers and copolymers.

[0047] Preferably, the base coat composition does not include the copolymer BBCP present in the coating composition used to form the top coat layer L2, so preferably the base coat composition does not include any polymer that is a copolymer BBCP.

[0048] The at least one polymer used as component (a1) can be self-crosslinking or non-self-crosslinking.Suitable polymers that can be used are known, for example, from EP0228003A1, DE4438504A1, EP0593454B1, DE19948004A1, EP0787159B1, DE4009858A1, DE4437535A1, WO92 / 15405A1 and WO2005 / 021168A1.

[0049] The at least one polymer used as component (a1) is preferably selected from the group consisting of polyurethanes, polyureas, polyesters, polyamides, polyethers, poly(meth)acrylates and / or copolymers of structural units of said polymers, in particular polyurethane-poly(meth)acrylates and / or polyurethane-polyureas. The at least one polymer used as component (a1) is particularly preferably selected from the group consisting of polyurethanes, polyesters, poly(meth)acrylates and / or copolymers of structural units of said polymers. The term "(meth)acrylic" or "(meth)acrylate" in the context of the present invention includes in each case the meanings "methacrylic" and / or "acrylic" or "methacrylate" and / or "acrylate".

[0050] Preferred polyurethanes are described, for example, in German patent application DE 19948 004 A1, page 4, line 19 to page 11, line 29 (polyurethane prepolymer B1), in European patent application EP 0 228 003 A1, page 3, line 24 to page 5, line 40, in European patent application EP 0 634 431 A1, page 3, line 38 to page 8, line 9, and in International patent application WO 92 / 15405, page 2, line 35 to page 10, line 32.

[0051] Preferred polyethers are described, for example, in WO2017 / 097642A1 and WO2017 / 121683A1.

[0052] Preferred polyesters are described, for example, in DE 4009858 A1, column 6, line 53 to column 7, line 61, and column 10, line 24 to column 13, line 3, or in WO 2014 / 033135 A2, page 2, line 24 to page 7, line 10, and page 28, line 13 to page 29, line 13. Likewise preferred polyesters are polyesters having a dendritic or star structure, which are described, for example, in WO 2008 / 148555 A1.

[0053] Preferred polyurethane-poly(meth)acrylate copolymers (eg (meth)acrylated polyurethanes) and their preparation are described, for example, in WO 91 / 15528 A1, page 3, line 21 to page 20, line 33, and in DE 4437535 A1, page 2, line 27 to page 6, line 22.

[0054] Preferred (meth)acrylic copolymers are OH-functional. Hydroxyl-containing monomers include hydroxyalkyl esters of acrylic or methacrylic acid that can be used to prepare the copolymer. 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, their reaction products with epsilon-caprolactone, and other hydroxyalkyl (meth)acrylates with branched or linear alkyl groups of up to about 10 carbons, and mixtures thereof. Hydroxyl groups on vinyl polymers, such as (meth)acrylic polymers, can be produced by other means, such as ring-opening of glycidyl groups, such as from polymerized glycidyl methacrylate, with organic acids or amines, etc. Hydroxyl functionality can also be introduced through thio-alcohol compounds, including, but not limited to, 3-mercapto-1-propanol, 3-mercapto-2-butanol, 11-mercapto-1-undecanol, 1-mercapto-2-propanol, 2-mercaptoethanol, 6-mercapto-1-hexanol, 2-mercaptobenzyl alcohol, 3-mercapto-1,2-propanediol, 4-mercapto-1-butanol, and combinations thereof. Any of these methods can be used to produce useful hydroxyl-functional (meth)acrylic polymers.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 the alkyl and cycloalkyl esters, nitriles, and amides of acrylic acid, methacrylic acid, and crotonic acid; α,β-ethylenically unsaturated dicarboxylic acids and anhydrides containing 4 to 6 carbon atoms, mono- 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 those esters from reaction with saturated aliphatic alcohols containing 1 to 20 carbon atoms, such as methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, tert-butyl, hexyl, 2-ethylhexyl, dodecyl, 3,3,5-trimethylhexyl, stearyl, lauryl, cyclohexyl, alkyl-substituted cyclohexyl, alkanol-substituted cyclohexyl, such as 2-tert-butyl and 4-tert-butylcyclohexyl, 4-cyclohexyl-1-butyl, 2-tert-butylcyclohexyl, 4-tert-butylcyclohexyl, 3,3,5,5-tetramethylcyclohexyl, tetrahydrofuran ... furyl, and isobornyl acrylate, isobornyl methacrylate, and isobornyl crotonate; unsaturated dialkanoic acids and anhydrides, such as fumaric acid, maleic acid, itaconic acid and anhydride, and their mono- and diesters with alcohols, such as methanol, ethanol, propanol, isopropanol, butanol, isobutanol, and tert-butanol, such as maleic anhydride, maleic acid dimethyl ester, and maleic acid monohexyl ester; vinyl acetate, vinyl propionate, vinyl ethyl ether, and vinyl ethyl ketone; styrene, a-methylstyrene, vinyl toluene, 2-vinylpyrrolidone, and p-tert-butylstyrene. (Meth)acrylic copolymers can be prepared using conventional techniques, for example by heating the monomers in the presence of a polymerization initiator and, optionally, a chain transfer agent.

[0055] Suitable poly(meth)acrylates can also be prepared by multi-stage free radical emulsion polymerization of olefinically unsaturated monomers in water and / or organic solvents. Examples of seed-core-shell polymers (SCS polymers) obtained by this method are disclosed in WO2016 / 116299A1.

[0056] Preferred polyurethane-polyurea copolymers are polyurethane-polyurea particles, preferably with a Z-average particle size of 40 to 2000 nm, polyurethane-polyurea particles containing at least one isocyanate group-containing polyurethane prepolymer containing at least one polyamine containing anionic groups and / or groups that can be converted into anionic groups, and at least one polyamine containing two primary amino groups and one or two secondary amino groups, each in reacted form. Preferably, such copolymers are used in the form of an aqueous dispersion. Such polymers can in principle be prepared, for example, by conventional polyaddition of polyisocyanates with polyols and polyamines.

[0057] The polymer used as component (a1) preferably has reactive functional groups that allow crosslinking reactions. Any common crosslinkable reactive functional groups known to those skilled in the art may be present. Preferably, the polymer used as component (a1) has at least one type of functional reactive group selected from the group consisting of primary amino groups, secondary amino groups, hydroxyl groups, thiol groups, carboxyl groups and carbamate groups. Preferably, the polymer used as component (a1) has functional hydroxyl groups and / or carbamate groups.

[0058] Preferably, the polymers used as component (a1) are hydroxyl-functional, more preferably having an OH number in the range of 15 to 400 mg KOH / g, more preferably 20 to 250 mg KOH / g.

[0059] The polymers used as component (a1) are particularly preferably hydroxyl-functional polyurethane-poly(meth)acrylate copolymers, hydroxyl-functional polyesters and / or hydroxyl-functional polyurethane-polyurea copolymers.

[0060] In addition, the basecoat composition may contain at least one typical crosslinking agent known per se. The crosslinking agent will be included in the film-forming non-volatile components of the coating composition and therefore falls within the general definition of "binder". Therefore, the crosslinking agent will be included in component (a1).

[0061] All conventional crosslinkers can be used. These include melamine resins, preferably melamine aldehyde resins, more preferably melamine formaldehyde resins, blocked polyisocyanates, polyisocyanates with free (unblocked) isocyanate groups, crosslinkers with amino groups, such as secondary and / or primary amino groups, and crosslinkers with epoxide and / or hydrazide groups, and crosslinkers with carbodiimide groups, as long as the functional groups of the particular crosslinker are suitable for reacting with the crosslinkable functional groups of the film-forming polymer used as the binder in the crosslinking reaction. For example, crosslinkers with blocked or free isocyanate groups can be reacted with the film-forming polymer with crosslinkable OH groups and / or amino groups at elevated temperature for 1K formulations and at ambient temperature for 2K formulations.

[0062] If a crosslinking agent is present, it is preferably at least one aminoplast resin and / or at least one blocked or free polyisocyanate, preferably an aminoplast resin. Among the aminoplast resins, melamine resins, such as melamine formaldehyde resins, are particularly preferred. Preferably, the melamine aldehyde resins, preferably the melamine formaldehyde resins, have in each case at least one of imino groups, alkylol groups and etherified alkylol groups as functional groups, which are reactive towards the functional groups of the polymer P1. An example of an alkylol group is a methylol group.

[0063] Coating layer L2 and the coating composition used to form said layer The second coating layer L2 is a topcoat layer and is applied on top of the first coating layer L1. Therefore, the second coating layer L2 is preferably located on top of the coating layer L1. The second coating layer L2 is formed from a coating composition comprising at least one block copolymer BBCP. This coating composition is also referred to herein as a topcoat composition and is the composition used in step (2) of the method of the present invention.

[0064] Preferably, the topcoat layer L2 is a clearcoat layer formed from a coating composition that is a clearcoat composition, preferably a solvent-based clearcoat composition, and the topcoat layer L2 is preferably the outermost coating layer of a multi-layer coating system.

[0065] Preferably, the coating composition comprising at least one block copolymer BBCP is a pigment-free or pigmented coating composition.

[0066] The topcoat composition may be an aqueous, i.e. water-based, coating composition. The topcoat composition may alternatively be a solvent-based topcoat composition. In particular, it is in fact a solvent-based topcoat composition. The topcoat composition applied in step (2) may be a 1K- (one component) composition or a 2K- (two component) composition. Preferably, it is a 1K- composition.

[0067] The topcoat composition is in particular a clearcoat composition. In this case, the clearcoat composition is preferably non-pigmented. However, the clearcoat composition may alternatively contain tinting and / or effect pigments, preferably tinting pigments, in an amount that does not interfere with the desired transparency of the clearcoat once cured. For example, the clearcoat composition may contain at most 7.5 wt.-%, preferably at most 5.0 wt.-%, more preferably at most 2.5 wt.-%, even more preferably at most 1.5 wt.-% of at least one tinting pigment, in each case relative to the total solids content of the clearcoat composition. The same applies to any fillers present in the clearcoat composition. However, preferably, the topcoat composition does not contain pigments and / or fillers.

[0068] Preferably, the total solids content of the topcoat composition is in the range of 15 to 70 wt.-%, more preferably 20 to 65 wt.-%, even more preferably 25 to 60 wt.-%, in particular 30 to 55 wt.-%, in each case based on the total mass of the topcoat composition. Methods for measuring the solids content (non-volatile content) are described in the "Methods" section hereinafter.

[0069] The topcoat composition necessarily comprises at least one block copolymer BBCP. As already outlined above, the block copolymers used in the present invention are also referred to hereinafter and earlier as copolymer BBCP.

[0070] Preferably, the at least one copolymer BBCP is present in the coating composition used to produce the second coating layer L2 in an amount ranging from 10 to 100 wt.-%, more preferably from 15 to 100 wt.-%, even more preferably from 20 to 95 wt.-%, in each case relative to the total solids content of the coating composition.

[0071] At least one block copolymer BBCP contains a main chain and at least two blocks B1 and B2, which are different from each other. Block B1 contains at least one type of side chain S1 attached to the main chain, and block B2 contains at least one type of side chain S2 attached to the main chain, which is different from side chain S1. Since each of the side chains S1 and S2 is attached to the main chain of the copolymer BBCP used in the present invention, said copolymer is necessarily a block copolymer comprising at least two blocks B1 and B2, where block B1 in turn comprises the previously mentioned side chain S1 and block B2 in turn comprises the previously mentioned side chain S2, it is clear that at least the part of the main chain of the copolymer used in the present invention to which the side chain S1 is attached is also part of block B1, and at least the part of the main chain of the copolymer used in the present invention to which the side chain S2 is attached is also part of block B2. It is further clear that the portions of block B1 which do not constitute at least one type of side chain S1 but to which side chain S1 is attached constitute part of the main chain of the copolymer, and that the portions of block B2 which do not constitute at least one type of side chain S2 but to which side chain S2 is attached also constitute part of the main chain of the copolymer. Each of the side chains S1 comprises at least one polymer moiety M1 selected from the group consisting of polyester, polyether and poly(meth)acrylate moieties, and each of the side chains S2 comprises at least one polymer moiety M2, different from the polymer moiety M1, selected from the group consisting of polyester, poly(meth)acrylate, polyether, polysiloxane and polystyrene moieties. The side chains S1 and S2 are preferably covalently attached to the main chain of the block copolymer BBCP. The main chain of the copolymer BBCP preferably, but not necessarily, comprises ethylenically unsaturated carbon-carbon double bonds.

[0072] The copolymer BBCP can be obtained by ring-opening metathesis polymerization (ROMP), preferably using cyclic ethylenically unsaturated, preferably cyclic olefinic, monomers. ROMP is a specific olefin metathesis chain growth polymerization. The driving force of this reaction is the relaxation of ring strain in cyclic olefins (such as norbornene or cyclopentene monomers).

[0073] Preferably, the main chain of the copolymer BBCP comprises olefinic carbon-carbon double bonds, more preferably arranged in a regular and / or repeating pattern, and even more preferably in such a way that each structural unit described later in this specification is covalently bonded to another structural unit via a carbon-carbon double bond. These double bonds are preferably formed during ROMP. When the copolymer BBCP is obtained in such a way, i.e. by ROMP, the formed carbon-carbon double bonds present in the main chain can be optionally hydrogenated later to saturated carbon bonds, such as alkylene moieties.

[0074] The skilled artisan is aware of methods for producing copolymers BBCP, in particular such copolymers produced via ROMP, and copolymers BBCP as such are known and are disclosed, for example, in WO2020 / 160299A1, WO2020 / 180427A1, as well as in BRSveinbjoernsson et al., PNAS2012, 109(36), pp. 14332-14336. The production of copolymers BBCP is also described in these references and, in the case of the cited journal articles, in the supporting information thereof.

[0075] The block copolymer BBCP is preferably a linear block copolymer. The block copolymer BBCP preferably has a block-like sequence of copolymerized structural units derived at least in part from a suitable ethylenically unsaturated monomer, preferably a cyclic olefin. Preferably, no (meth)acrylic monomers are used to prepare the block copolymer BBCP.

[0076] The block copolymer BBCP comprises at least two blocks and is therefore at least a diblock copolymer, more preferably a linear diblock copolymer, however, the copolymer BBCP may also comprise additional blocks, for example a triblock copolymer.

[0077] Block copolymers are copolymers obtained by adding at least two different ethylenically unsaturated monomers, two different mixtures of ethylenically unsaturated monomers, or by adding ethylenically unsaturated monomers and mixtures of ethylenically unsaturated monomers at different times in the practice of controlled polymerization, where ethylenically unsaturated monomers, or mixtures of ethylenically unsaturated monomers, are initially charged at the beginning of the reaction. When adding further ethylenically unsaturated monomers, or mixtures of ethylenically unsaturated monomers, or adding ethylenically unsaturated monomers in multiple portions, the ethylenically unsaturated monomers added at the beginning of the polymerization may already be fully reacted or still partially unpolymerized. As a result of such polymerization, block copolymers may have at least one transition in their structural units along the polymer chain (polymer backbone), which marks the boundary between the individual blocks. Suitable block copolymer structures are, for example, AB diblock copolymers, ABA triblock copolymers, or ABC triblock copolymers. The block copolymers preferably used according to the present invention contain blocks with a minimum number of two structural units per block.

[0078] Preferably, the block copolymer BBCP is of the type AB, ABA, BAB, ABC and / or ACB, the A, B and C blocks representing different compositions of structural units, the blocks A, B and C differing in their respective compositions of structural units and / or the amount of structural units in two adjacent blocks differing from each other in each case by more than 5% by weight. Most preferred, however, are AB diblock copolymers.

[0079] Preferably, the at least one copolymer BBCP present in the second base coat composition has a number average molecular weight (M) in the range of 450 to 3000 kDa, more preferably in the range of 500 to 2500 kDa, even more preferably in the range of 550 to 2000 kDa, still more preferably in the range of 600 to 1500 kDa, in particular in the range of 650 to 1000 kDa. n ).

[0080] Number average molecular weight (M n ), and for measuring the weight average molecular weight (M w Methods for measuring the molecular weight, molecular weight, and polydispersity index (PDI) are described in the "Methods" section later in this specification.

[0081] As mentioned hereinbefore, each of the side chains S1 comprises at least one polymer moiety M1 selected from the group consisting of polyester, polyether and poly(meth)acrylate moieties, and each of the side chains S2 comprises at least one polymer moiety M2 different from the polymer moiety M1 and selected from the group consisting of polyester, poly(meth)acrylate, polyether, polysiloxane and polystyrene moieties.

[0082] Preferably, the side chains are not introduced into the copolymer BBCP after it has already been polymerized in a polymer-analogous reaction. Instead, the side chains are preferably introduced into the suitable monomers used in the polymerization reaction to prepare the copolymer BBCP. The corresponding monomers represent macromonomers since these monomers have the polymeric portion described above.

[0083] Preferably, cyclic olefins, more preferably norbornene or cyclopentene monomers, are used to prepare the copolymer BBCP. Polymer moieties, such as M1 and M2, can be introduced into such monomers, for example, by using norbornene or cyclopentene monomers having at least one functional group, such as a carboxylic acid group and / or a hydroxyl group. Examples of suitable norbornene monomers are: [ka] For example, (B) can be used as an initiator alcohol for polymerization, such as tin-catalyzed polymerization of lactide, such as racemic lactide, to produce a polylactide macromonomer with both OH-functional end groups, which is norbornene-functionalized at the other end. The polylactide unit represents a polyester moiety as an example of the polymer moiety M1. The norbornene moiety can then be used in ROMP to produce a copolymer BBCP. The preparation of such macromonomers is described, for example, in the supporting information of BRSveinbjoernsson et al., PNAS 2012, 109(36), pp. 14332-14336. Monomer (A) can also be used to produce a suitable macromonomer suitable for ROMP. For example, a polymer, such as polystyrene, can be produced with a terminal OH group. The terminal OH group of this formed precursor can then be transformed into an ester bond via reaction with (A) to produce a suitable macromonomer with a polystyrene moiety as the polymer moiety M2. The preparation of such macromonomers is described, for example, in Example 2 of WO2020 / 180427A1.

[0084] Preferably, each of the side chains S1 of the first block B1 of the copolymer BBCP comprises at least one polymer moiety M1 containing at least one, preferably terminal, hydroxyl group, the polymer moiety M1 being preferably selected from the group consisting of aliphatic polyester moieties and preferably aliphatic polyether moieties, in particular representing a polylactide moiety, and also preferably, each of the side chains S2 of the second block B2 of the copolymer BBCP comprises at least one polymer moiety M2 which does not contain both a hydroxyl group and a carboxylic acid group, the polymer moiety M2 being preferably selected from the group consisting of polyether, polysiloxane and polystyrene moieties, in particular representing a polystyrene moiety.

[0085] Preferably, the first block B1 of the copolymer BBCP comprises at least one structural unit SU1a and optionally at least one structural unit SU1b, the structural unit SU1a being represented by at least one of the partial structures PS1a-1 and PS1a-2, the optionally present structural unit SU1b being represented by the partial structure PS1b, all structural units present in the first block being preferably randomly arranged within the first block B1 of the copolymer BBCP: [ka] wherein, independently of each other, The parameter x is in the range of 1 to 1000, preferably 1 to 750, more preferably 2 to 500, and even more preferably 3 to 300; The parameter a is in the range of 0 to 1000, preferably 1 to 750, more preferably 2 to 500, and even more preferably 3 to 300; the relative ratio of parameter x:parameter a is in the range of 1:0 to 1:3, preferably 2:1 to 1:2; Mx, J1 and G each independently represent CH2 or C=O; Q represents a divalent alkyl, heteroalkyl, cycloalkyl, heterocycloalkyl, aryl, or heteroaryl residue; Rx represents a side chain S1 containing a polymer moiety M1, preferably C2-C6-alkylene-O-[C(=O)-C2-C6-alkylene-O] n -H, where the parameter n is in the range of 1 to 500, preferably 1 to 300, R1 represents a C1-C6-alkyl residue, preferably an unbranched C1-C6-alkyl residue.

[0086] Preferably, the second block B2 of the copolymer BBCP comprises at least one structural unit SU2a and optionally at least one structural unit SU2b, the structural unit SU2a being represented by at least one of the partial structures PS2a-1 and PS2a-2, the optionally present structural unit SU2b being represented by the partial structure PS2b, all structural units present in the second block being preferably randomly arranged within the second block B2 of the copolymer BBCP: [ka] wherein, independently of each other, The parameter y is in the range of 1 to 1000, preferably 1 to 750, more preferably 2 to 500, and even more preferably 3 to 300; The parameter b is in the range of 0 to 1000, preferably 1 to 750, more preferably 2 to 500, and even more preferably 3 to 300; the relative ratio of parameter y to parameter b is in the range of 1:0 to 1:3, preferably 2:1 to 1:2; My, J2 and G each independently represent CH2 or C=O; Q represents a divalent alkyl, heteroalkyl, cycloalkyl, heterocycloalkyl, aryl, or heteroaryl residue; Ry represents a side chain S2 comprising a polymer moiety M2, preferably C1-C8-alkylene-ZT, where Z represents C(=O)-O) or a divalent N-containing heterocyclic residue and T represents a C1-C4-alkylene residue to which a polystyrene moiety is attached; R2 represents a C1-C6-alkyl residue, preferably a branched C1-C6-alkyl residue.

[0087] Preferably, the parameter a and the parameter b are each independently 1 to 300, 5 to 50, 50 to 100, 100 to 150, 150 to 200, 200 to 250, 250 to 300, 300 to 400, 400 to 500, 500 to 600, 600 to 700, 700 to 800, 800 to 900, or 900 to 1000. Preferably, x and y are each independently 1 to 300, 5 to 50, 50 to 100, 100 to 150, 150 to 200, 200 to 250, 250 to 300, 300 to 400, 400 to 500, 500 to 600, 600 to 700, 700 to 800, 800 to 900, or 900 to 1000. Preferably, the ratio of x:a is 1:0.5 to 1:1, 1:1.5, 1:2, or 1:2.5. Preferably, the ratio of y:b is 1:0.5 to 1:1, 1:1.5, 1:2, or 1:2.5.

[0088] Preferably, a+x+b+y is in the range of 100-500, more preferably 120-480, even more preferably 140-400, still more preferably 160-350, especially 180-300.

[0089] The term "alkyl" refers to a branched or unbranched hydrocarbon having, for example, 1 to 20 carbon atoms, often 1 to 12, 1 to 10, 1 to 8, 1 to 6 or 1 to 4 carbon atoms, or in the range of, for example, between 1 to 20 carbon atoms, for example, 2 to 6, 3 to 6, 2 to 8, or 3 to 8 carbon atoms. Examples include, but are not limited to, methyl, ethyl, 1-propyl, 2-propyl, 1-butyl, 2-methyl-1-propyl (isobutyl), 2-butyl (sec-butyl), 2-methyl-2-propyl ( / -butyl), 1-pentyl, 2-pentyl, 3-pentyl, 2-methyl-2-butyl, 3-methyl-2-butyl, 3-methyl-1-butyl, 2-methyl-1-butyl, 1-hexyl, 2-hexyl, 3-hexyl, 2-methyl-2-pentyl, 3-methyl-2-pentyl, 4-methyl-2-pentyl, 3-methyl-3-pentyl, 2-methyl-3-pentyl, 2,3-dimethyl-2-butyl, 3,3-dimethyl-2-butyl, hexyl, octyl, decyl, and dodecyl. Alkyl can be unsubstituted or substituted. The term "heteroalkyl" is understood to be an alkyl as defined above, preferably having at least one heteroatom and / or at least one heteroatom-containing group selected from nitrogen, sulfur, oxygen. The term "cycloalkyl" refers to a cyclic alkyl group, preferably of 3 to 10 carbon atoms, for example, having a single cyclic ring or multiple condensed rings. Cycloalkyl groups include, by way of example, single ring structures, such as cyclopropyl, cyclobutyl, cyclopentyl, cyclooctyl, or multiple ring structures, such as adamantyl. Cycloalkyl groups can be unsubstituted or substituted. Cycloalkyl groups can be monovalent or divalent and can be optionally substituted as described for alkyl groups. Cycloalkyl groups can optionally contain one or more sites of unsaturation, for example, cycloalkyl groups can contain one or more carbon-carbon double bonds. The term "heterocycloalkyl" refers to a saturated or partially saturated monocyclic, bicyclic, or polycyclic ring, preferably containing at least one heteroatom selected from nitrogen, sulfur, oxygen, preferably 1 to 3 heteroatoms in at least one ring.Each ring is preferably 3 to 10 members, more preferably 4 to 7 members. Examples of suitable heterocycloalkyls include pyrrolidyl, tetrahydrofuryl, tetrahydrothiofuranyl, piperidyl, piperazyl, tetrahydropyranyl, morpholino, 1,3-diazapane, 1,4-diazapane, 1,4-oxathiapane, and 1,4-oxazepane. These groups may be terminal or bridging groups. The term "aryl" preferably refers to an aromatic hydrocarbon group. An aryl group can have 6 to 30 carbon atoms, for example about 6 to 10 carbon atoms. Alternatively, an aryl group can have 6 to 60 carbon atoms, 6 to 120 carbon atoms, or 6 to 240 carbon atoms. An aryl group can have a single ring (e.g., phenyl) or multiple condensed (fused) rings, with at least one ring being aromatic (e.g., naphthyl, dihydrophenanthrenyl, fluorenyl, or anthryl). Typical aryl groups include, but are not limited to, groups derived from benzene, naphthalene, anthracene, and biphenyl. Aryl may be unsubstituted or optionally substituted. The term "heteroaryl" refers to a monocyclic, bicyclic, or tricyclic ring system, preferably containing one, two, or three aromatic rings, and containing at least one nitrogen atom, oxygen atom, or sulfur atom, and / or a heteroatom-containing group in the aromatic ring. Heteroaryl may be unsubstituted or substituted, for example, with one or more, especially one to three, substituents. Typical heteroaryl groups contain 2 to 20 carbon atoms in the ring backbone in addition to one or more heteroatoms.Examples of heteroaryl groups include 2H-pyrrolyl, 3H-indolyl, 4H-quinolizinyl, acridinyl, benzo[b]thienyl, benzothiazolyl, b-carbolinyl, carbazolyl, chromenyl, cinnolinyl, dibenzo[b,d]furanyl, furazanyl, furyl, imidazolyl, imidizolyl, indazolyl, indolisinyl, indolyl, isobenzofuranyl, isoindolyl, isoquinolyl, isothiazolyl, isoxazolyl, naphthyridinyl, oxazolyl, perimine, and the like. Examples of heteroaryl include, but are not limited to, diphenyl, phenanthridinyl, phenanthrolinyl, phenarsazinyl, phenazinyl, phenothiazinyl, phenoxathiinyl, phenoxazinyl, phthalazinyl, pteridinyl, purinyl, pyranyl, pyrazinyl, pyrazolyl, pyridazinyl, pyridyl, pyrimidinyl, pyrrolyl, quinazolinyl, quinolyl, quinoxalinyl, thiadiazolyl, thianthrenyl, thiazolyl, thienyl, trizolyl, tetrazolyl, and xanthenyl. Preferably, "heteroaryl" refers to a monocyclic aromatic ring containing 5 or 6 ring atoms containing 1, 2, 3, or 4 heteroatoms independently selected from carbon and non-peroxy oxygen, sulfur, and N(Z), where Z is absent or is H, O, alkyl, aryl, or (C1-C6)alkylaryl. Heteroaryl may also refer to ortho-fused bicyclic heterocycles of about 8-10 ring atoms derived therefrom, particularly benz derivatives, or those derived therefrom by fusing a propylene, trimethylene or tetramethylene diradical thereto. As used herein, the term "substituted" or "substituent" preferably means that one or more (e.g., 1-20, or 1-10, or 1, 2, 3, 4 or 5, or 1, 2 or 3, or 1 or 2) hydrogens on the group indicated in the expression with "substituted" (or "substituent") are replaced with a suitable group selected from the indicated group or known to those skilled in the art, provided that the normal valence of the indicated atom is not exceeded and that the replacement results in a stable compound.Suitable indicated groups include, for example, alkyl, alkenyl, alkynyl, alkoxy, halo, haloalkyl, hydroxy, hydroxyalkyl, aryl, heteroaryl, heterocyclyl, cycloalkyl, alkanoyl, alkoxycarbonyl, amino, alkylamino, dialkylamino, trifluoromethylthio, difluoromethyl, acylamino, nitro, trifluoromethyl, trifluoromethoxy, carboxy, carboxyalkyl, keto, thioxo, alkylthio, alkylsulfumyl, alkylsulfonyl, and cyano. Additionally, non-limiting examples of substituents which may be bonded to a substituted carbon atom (or other atom) include F, Cl, Br, I, OR', OC(=O)N(R')2, CN, CF3, OCF3, R', O, S, C(=0), methylenedioxy, ethylenedioxy, N(R')2, SR', SOR', SOR', SOR', SON(R')2, SOR', C(=O)R', C(=O)C(=O)R', C(=O)CH2C(=O)R', C(=S)R', C(=O)OR', OC(=O)R', C(=O)N(R')2, OC(=O)N(R')2, C(=S)N(R')2, (CH2). 0~2 and NHC(=O)R', N(R')N(R')C(=O)R', N(R')N(R')C(=O)OR', N(R')N(R')CON(R')2, N(R')SOR', N(R')SON(R')2, N(R')C(=O)OR', N(R')C(=O)R', N(R')C(S)R', N(R')C(=O)N(R')2, N(R')C(S)N(R')2, N(COR')COR', N(OR')R', C(=NH)N(R')2, C(=O)N(OR')R' or C(=NOR')R' (where R' can be a hydrogen or carbon based moiety).

[0090] Since the main chain of the copolymer BBCP preferably contains ethylenically unsaturated carbon-carbon double bonds, the structural units present in each block are preferably covalently bonded in such a way that each of the units is bonded to another unit via a carbon-carbon double bond. The copolymer BBCP further preferably contains two end groups when it is linear, which is preferred. Each of these end groups is covalently bonded to one structural unit. The end groups (i.e., the initial or final end) of the copolymer are preferably low molecular weight moieties (e.g., less than 500 Da), such as H, OH, COOH, CH2OH, CN, NH2, or hydrocarbons, such as alkyl (e.g., butyl or 2-cyanoprop-2-yl moieties at the initial and final ends), alkenes or alkynes, or moieties resulting from elimination reactions at the first and / or last repeating units in the copolymer.

[0091] Preferably, the block copolymer BBCP is a brush block copolymer. A brush block copolymer comprises a main chain (backbone) with linear, unbranched side chains. Brushes are often characterized by a high density of grafted chains. The limited space then allows the side chains to stretch strongly.

[0092] Preferably, the first block B1 of the copolymer BBCP comprises at least one structural unit SU1a represented by at least the partial structure PS1a-1 and further comprises at least one structural unit SU1b represented by the partial structure PS1b, and the second block B2 of the copolymer BBCP comprises at least one structural unit SU2a represented by at least the partial structure PS2a-1 and further comprises at least one structural unit SU2b represented by the partial structure PS1b: Here, independently of each other, The parameter x is in the range of 2 to 500, preferably 3 to 300; The parameter a is in the range of 2 to 500, preferably 3 to 300; the relative ratio of parameter x:parameter a is in the range of 2:1 to 1:2, preferably 1.5:1 to 1:1.5; The parameter y is in the range of 2 to 500, preferably 3 to 300; The parameter b is in the range of 2 to 500, preferably 3 to 300; The relative ratio of parameter y:parameter b is in the range of 2:1 to 1:2, preferably 1.5:1 to 1:1.5, and the remaining residues and variables have one or more of the meanings previously defined herein.

[0093] Preferably, the coating composition comprising at least one block copolymer BBCP used to prepare the second coating layer L2 further comprises at least one homopolymer, preferably linear, more preferably selected from homopolymers of polyesters, poly(meth)acrylates, polyethers, polysiloxanes and polystyrene, even more preferably selected from homopolymers of polystyrene, polyethers and polyesters, and mixtures thereof, even more preferably selected from homopolymers of polystyrene and aliphatic polyesters, such as polylactide homopolymers, and mixtures thereof, the at least one homopolymer having a number average molecular weight (M n The number average molecular weight (M n ), and preferably the relative weight ratio of BBCP copolymer solids to the at least one homopolymer solids in the coating composition is in the range of from 99:1 to 5:95, more preferably from 95:5 to 10:90, even more preferably from 90:10 to 15:85, still more preferably from 85:15 to 20:80, even more preferably from 75:25 to 25:75, especially from 60:40 to 30:70. n ), and for measuring the weight average molecular weight (M w Methods for measuring the molecular weight, molecular weight, and polydispersity index (PDI) are described in the "Methods" section later in this specification.

[0094] Methods for producing such homopolymers are disclosed, for example, in WO2020 / 160299A1 (pages 25 / 26, Example 1) and WO2020 / 180427A1 (pages 25 / 26, Example 1).

[0095] Preferably, the at least one homopolymer is present in the topcoat composition in an amount ranging from 0 to 90 wt.-%, preferably from 20 to 80 wt.-%, more preferably from 40 to 60 wt.-% and in particular from 30 to 70 wt.-%, in each case based on the total solids content of the topcoat composition.

[0096] Preferably, the relative weight ratio of BBCP copolymer solids to said at least one homopolymer solids in the topcoat composition is in the range of from 99:1 to 5:95, preferably from 95:5 to 10:90, more preferably from 90:10 to 15:85, even more preferably from 85:15 to 20:80, still more preferably from 75:25 to 25:75, especially from 60:40 to 30:70.

[0097] Preferably, the coating composition comprising at least one block copolymer BBCP used to prepare the second coating layer L2 comprises, besides the copolymer BBCP and besides the at least one homopolymer defined above if such homopolymer is present, at least one further resin, more preferably at least one polymeric resin, the relative weight ratio of BBCP copolymer solids to the solids of the at least one further resin in the coating composition being preferably in the range of 5:95 to 100:0, more preferably 10:90 to 100:0, even more preferably 15:85 to 95:5, still more preferably 20:80 to 90:10, still more preferably 25:75 to 85:15, in particular 30:70 to 80:20 and most preferably 40:60 to 80:20.

[0098] Preferably, the topcoat composition comprises, other than the copolymer BBCP, and other than the at least one homopolymer as hereinbefore defined, if such homopolymer is present, at least one further resin, preferably at least one polymeric resin, and the relative weight ratio of the sum of BBCP copolymer solids and homopolymer solids (if present) to the solids of the at least one further resin in the topcoat composition is preferably in the range of from 40:60 to 100:0, more preferably from 45:55 to 100:0, even more preferably from 50:50 to 95:5, still more preferably from 55:45 to 90:10, still more preferably from 60:40 to 85:15.

[0099] At least one further resin, preferably at least one polymeric resin, optionally present in the topcoat composition other than the copolymer BBCP and other than the at least one homopolymer, preferably functions as at least one binder (b1). The same binders, including crosslinkers (crosslinking agents), previously described herein in connection with component (a1) can also be used as component (b1). The at least one polymeric component (b1) optionally present is of course different from the copolymer BBCP and from the homopolymer previously described.

[0100] Preferably, the topcoat composition comprises at least one polymer (c1) having on average two or more OH- and / or amino- and / or carbamate groups, more preferably OH- and / or carbamate groups. Preferably, the at least one, preferably at least OH- and / or carbamate-functional polymer (c1) has a weight average molecular weight M, 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 has.

[0101] If the topcoat composition is formulated as a 2K coating composition, it preferably contains, as the at least one further polymer (c1) present therein, at least one polyisocyanate with free NCO groups as crosslinking agent. If the topcoat composition is formulated as a 1K coating composition, it preferably contains, as the at least one further polymer (c1) present therein, at least one polyisocyanate with blocked NCO groups and / or at least one melamine formaldehyde resin as crosslinking agent.

[0102] Component (c1) suitable for use as crosslinking agent is an organic component having on average two or more NCO groups. At least one organic component used as crosslinking agent preferably has an alicyclic structure and / or parent structure derived from an alicyclic polyisocyanate by trimerization, dimerization, urethane formation, biuret formation, uretdione formation and / or allophanate formation. Alternatively or additionally, at least one organic component used as crosslinking agent preferably has an acyclic aliphatic structure and / or parent structure derived from an acyclic aliphatic polyisocyanate by trimerization, dimerization, urethane formation, biuret formation, uretdione formation and / or allophanate formation. The acyclic aliphatic polyisocyanate (which optionally serves as the parent structure) is a per se known, preferably substituted or unsubstituted aliphatic polyisocyanate. 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. The cycloaliphatic polyisocyanates (which optionally serve as parent structures) are preferably substituted or unsubstituted cycloaliphatic polyisocyanates which are known per se. Examples of preferred polyisocyanates are isophorone diisocyanate, cyclobutane 1,3-diisocyanate, cyclohexane 1,3-diisocyanate, cyclohexane 1,4-diisocyanate, methylcyclohexyl diisocyanate, hexahydrotoluene 2,4-diisocyanate, hexahydrotoluene 2,6-diisocyanate, hexahydrophenylene 1,3-diisocyanate, hexahydrophenylene 1,4-diisocyanate, perhydrodiphenylmethane 2,4'-diisocyanate, 4,4'-methylenedicyclohexyl diisocyanate (e.g. Desmodur® W from Bayer AG), as well as mixtures of the aforementioned polyisocyanates. The organic components listed above, which have on average two or more NCO groups, can also be partially silanized.Such silanated crosslinkers are disclosed, for example, in WO2010 / 063332A1, WO2010 / 139375A1 and WO2009 / 077181A1.

[0103] Component (c1) suitable for use as a crosslinker, especially when the topcoat composition is formulated as a 1K coating composition, is a melamine formaldehyde resin. In connection with component (a1), the same melamine formaldehyde resins already discussed earlier in this specification can be used.

[0104] Methods of the Invention The method of the present invention is a method for producing the multi-layer coating system of the present invention on an optionally pre-coated substrate, comprising at least steps (1), (2) and (3).

[0105] The method of the present invention is suitable for both automotive OEM and refinish applications, especially automotive OEM applications.

[0106] Preferably, each of steps (1) and (2) is carried out via spray application.

[0107] At least the second coating film, but also optionally the first coating film, is an uncured coating film before the step (3) is performed. The coating composition applied in step (2) may be applied wet-on-wet onto the first coating film obtained after performing step (1). In this case, the first and second coating films obtained are cured or dried together in step (3), and the method of the present invention is a 2C1B method. Alternatively, the first coating film applied in step (1) is cured before performing step (2). In this case, only the second coating film is cured or dried in step (3).

[0108] Process (1) According to step (1), preferably a pigmented basecoat composition is applied to an optionally precoated substrate and a first coating film is formed on at least a portion of the optionally precoated substrate.

[0109] Optional Step (1a) Preferably, the method of the present invention further comprises a step (1a), which is carried out after step (1) and before step (2). In said step (1a), the first coating film obtained after step (1) is flashed off, preferably for a period of 1 to 20 minutes, more preferably for a period of 2 to 15 minutes, in particular for a period of 5 to 10 minutes, before applying the top coat composition in step (2). Preferably, step (1a) is carried out at a temperature not exceeding 40°C, more preferably at a temperature in the range of 18 to 30°C.

[0110] The term "flushing off" in the sense of the present invention preferably means drying, whereby at least some and / or some amount of solvent (water and / or organic solvent) is evaporated from the coating film before the next coating composition is applied and / or curing is carried out. No curing is carried out by flushing off.

[0111] Optional step (1b) Preferably, the method of the present invention further comprises step (1b), which is carried out after step (1) or step (1a) and before step (2). In said step (1b), the first coating film obtained after step (1) or (1a) is cured or dried before applying the topcoat composition in step (2). In relation to step (3), the same curing or drying conditions can be used / applied, as outlined in detail later in this specification.

[0112] Preferably, steps (1a) and / or (1b) are performed. More preferably, at least step (1b) is performed such that the topcoat composition applied in step (2) is applied onto the cured first coating film.

[0113] Process (2) According to step (2), a topcoat composition, comprising at least one block copolymer BBCP and different from the basecoat composition applied in step (1), is applied to the first coating film present on the substrate obtained after step (1), preferably forming a second coating film adjacent to the first coating film, said topcoat composition being preferably a clearcoat composition.

[0114] Step (2) can be carried out before curing the first coating film obtained after step (1). Alternatively, and preferably, step (2) is carried out after curing the first coating film obtained after step (1), i.e. after carrying out at least optional step (1b).

[0115] Preferably, the second coating film obtained after step (2) is the outermost film of the formed multi-layer coating system.

[0116] Optional step (2a) Preferably, the method of the present invention further comprises a step (2a), which is carried out after step (2) and before step (3). In said step (2a), the second coating film obtained after step (2) is flashed off, preferably for a period of 1 to 20 minutes, more preferably for a period of 2 to 15 minutes, in particular for a period of 5 to 10 minutes, before step (3) is carried out. Preferably, step (2a) is carried out at a temperature not exceeding 40°C, more preferably at a temperature in the range of 18 to 30°C.

[0117] Process (3) According to step (3), the second coating film applied in step (2), and optionally also the first coating film applied in step (1), if the first coating film was not cured or dried before carrying out step (2), are cured or dried / co-cured or dried, i.e. cured or dried simultaneously, to obtain a multi-layer coating system with at least a first and a second coating layer L1 and L2. Each obtained cured or dried coating film represents a coating layer.

[0118] Preferably, when curing is carried out as step (3), step (3) is carried out at a temperature below 180°C, preferably below 160°C, more preferably below 150°C, in particular at a temperature in the range of 15 to <180°C or 15 to <160°C, for a period of 5 to 45 minutes, preferably for a period of 20 to 45 minutes, in particular for a period of 25 to 35 minutes.

[0119] Preferably, when drying is carried out as step (3), step (3) is carried out at a temperature below 140°C, preferably below 100°C, more preferably below 80°C, in particular at a temperature in the range of 15 to <100°C or 15 to <80°C, for a period of 60 minutes to 48 hours, preferably for a period of 80 minutes to 36 hours, more preferably for a period of 90 minutes to 26 hours.

[0120] Preferably, the curing according to step (3) is selected from chemical curing, such as chemical crosslinking, and radiation curing, in each case at room temperature or at elevated temperature. Preferably, the drying according to step (3) means physical drying (non-chemical curing), in each case at room temperature or at elevated temperature. Most preferred is chemical curing, such as chemical crosslinking, and / or physical drying (non-chemical curing), in each case at room temperature or at elevated temperature.

[0121] Coated Substrates of the Present Invention A further subject of the invention is a coated substrate obtainable by the method according to the invention.

[0122] All preferred embodiments described hereinabove in relation to the inventive method and the inventive multi-layer coating system are also preferred embodiments in relation to the inventive coated substrate described above.

[0123] Methods of using the present invention A further subject of the present invention is the ability to improve, in particular to increase, preferably improve, the color strength of a coating composition comprising at least one block copolymer BBCP used according to the invention, in particular a multi-layer coating system according to the invention, in particular its C* 平均 The method used to increase the saturation value, C* 平均 The chroma value is preferably selected to improve the sum of the C* values ​​(chroma values ​​according to the L*C*h color model) measured at angles of 15°, 45° and 110°, particularly when the coating composition is used as a topcoat composition in step (2) of the method of the present invention. 平均 A chroma value of at least 40, preferably at least 42, more preferably at least 45, even more preferably at least 50, still more preferably at least 55, in particular at least 60, C* 平均 It is divided by 3 to bring it up to value.

[0124] All preferred embodiments described hereinabove with respect to the inventive method, the inventive multi-layer coating system and the inventive coated substrate are also preferred embodiments with respect to the inventive method of using as described above.

[0125] method 1. Determination of Nonvolatile Fraction The amount of solids (non-volatile matter, solid fraction), including the total solids, is determined via DIN EN ISO 3251:2019-09 at 110° C. for 60 min.

[0126] 2.M n , M w and PDI measurements Polymer molecular weight (number average molecular weight (M n) and mass average molecular weight (M W The molecular weight distribution (PDI, polydispersity index) as well as the molecular weight distribution (PDI) were determined via gel permeation chromatography (GPC) using a combination of differential refractive index (dRI) and two light scattering (LS) detectors. The use of the LS detector allows the analysis of absolute molecular weight for the polymer samples. The solvent for all samples was tetrahydrofuran (THF) with an elution rate of 1.0 mL / min. The polymer samples were completely dissolved in HPLC grade THF at concentrations ranging from 2.5 to 7.5 mg / mL, passed through a 0.5 um syringe filter and injected via an autosampler. The porous column stationary phase consisted of two Malvern T600 single-hole columns with an exclusion limit of 20,000,000 Da for poly(styrene). Molecular weights and PDI were determined via OMNISEC software.

[0127] 3. Color values ​​(L* and C*) and R f value and λ max Measurement of values The L*a*b* color space or L*a*b* color model (i.e., the CIELAB color model) is known to those skilled in the art. The L*a*b* color model is standardized, for example, in DIN EN ISO / CIE11664-4:2020-03. Each perceivable color in the L*a*b* color space is described by the location of a particular color with coordinates {L*, a*, b*} in a three-dimensional coordinate system. The a* axis describes the green or red part of the color, with negative values ​​representing green and positive values ​​representing red. The b* axis describes the blue or yellow part of the color, with negative values ​​being blue and positive values ​​being yellow. Smaller numbers thus indicate a more bluish color. The L* axis is perpendicular to this plane and represents lightness. The L*C*h color model is similar to the L*a*b* color model and utilizes the same diagram as the L*a*b* color model, but utilizes cylindrical coordinates instead of Cartesian coordinates. In the L*C*h color model, L* also indicates brightness, C* represents chroma, and h is the hue angle. The value of chroma C* is the distance from the axis of brightness (L*). The color values ​​L* and C* of the coated substrate before or after firing are determined after its production in accordance with ASTM E284-81a. The values ​​are measured by utilizing the instrument BYK-mac i (BYK-Gardner). The analysis of the samples is carried out in accordance with the measurement of color, glitter and graininess using the BYK-mac i spectrophotometer standard operating procedure. The sample to be analyzed is carefully wiped clean with a microfiber cloth. The BYK-mac i instrument is then placed on the substrate surface and measurements are carried out with a D65 illuminant at angles of 15°, 45° and 110°, and data are recorded for each angle. The measurements are taken at least three different positions on each panel, and the values ​​are averaged over the test and reported. λ max The values ​​were measured on the x-axis of the reflectance curve taken with a BYK-mac i spectrophotometer at angles of 15°, 45° and 110°, data was recorded for each angle and the reflectance values ​​(R f ) is the maximum between 400nm and 700nm (measurement window). fThe values ​​were measured on the y-axis of the reflectance curve taken with a BYK-mac i spectrophotometer at angles of 15°, 45° and 110°, data was recorded for each angle and the reflectance values ​​(R f ) is the maximum between 400 nm and 700 nm (measurement window). EXAMPLES

[0128] The following examples further illustrate the present invention but should not be construed as limiting its scope. "Pbw" means parts by weight. Unless otherwise defined, "parts" means "parts by weight".

[0129] 1. Preparation of the copolymer used in the present invention In a 2000 mL container under inert atmosphere, add norbornene-functionalized polylactide macromonomer (PLA-MM) (29.14 mmol, M of 3.26 kDa). n (with d = endo, x = exo) and d,x-DME (dimethyl-5-norbornene-2,3-dicarboxylate, where d = endo, x = exo) were added in equimolar amounts in dichloromethane. PLA-MM was previously prepared via tin-catalyzed ring-opening polymerization of lactide using norbornene alcohol initiator to obtain OH-functionalized and norbornene-functionalized polylactide macromonomer PLA-MM. PLA-MM was prepared by the general method described in the supporting information of BRSveinbjoernsson et al., PNAS 2012, 109(36), pp. 14332-14336. Bis-bipyridine ruthenium catalyst was then quickly added to the mixture of PLA-MM and d,x-DME to obtain PLA 100 -r-DME 100 The copolymerization was started with the target of PLA. "r" means that the two monomer units PLA and DME are randomly arranged. The mixture was stirred at room temperature for 45 minutes (first block mixture). In a separate container under inert atmosphere, norbornene-functionalized polystyrene macromonomer (PS-MM, M of 3.83 kDa) was added to the mixture. nA solution of d,x-DIPE (diisopropyl-5-norbornene-2,3-dicarboxylate, d=endo, x=exo) was prepared in dichloromethane (second block mixture). PS-MM was previously prepared in two steps in the general manner described in Example 2 of WO2020 / 180427A1, and an OH-functional polymerization precursor of PS-MM was prepared by polymerization of styrene in toluene with sec-butyllithium as initiator. After chain termination by addition of propylene oxide followed by methanol, quenching was performed. The terminal OH group of the formed precursor was then converted into an ester bond via reaction with norbornene carboxylic acid to obtain PS-MM. A solution of PS-MM and d,-DIPE was quickly added to the first block reaction mixture. In the formed second block of the copolymer, the two monomer units PS and DIPE are randomly arranged. The resulting mixture was stirred at room temperature for another 4 hours and then quenched by adding ethyl vinyl ether. The quenched catalyst was then captured using a functionalized silica gel absorbent, which was stirred for about 4 hours. The mixture was filtered and the solution was concentrated under reduced pressure. A solid copolymer was obtained after removing the solvent. It was dried in a vacuum oven at 75° C. for 4 hours to remove remaining solvent. The resulting product (BBCP1) was used in this form.

[0130] BBCP1 has a number-average molecular weight (M n ), and a mass average molecular weight (M w The polydispersity index (PDI) was correspondingly 1.10.

[0131] 2. Preparation of BBCP1 containing coating composition 2.1 Topcoat compositions TC1 to TC5 TC1 was obtained by preparing a solution of 1.80 g BBCP1, 0.60 g polystyrene homopolymer (PS-HP), 0.60 g polylactide homopolymer (PLA-HP) and 7 g n-butyl acetate. The relative mass ratio of BBCP1 solids to the combined PS-HP and PLA-HP solids in TC1 was 60:40.

[0132] TC2 was obtained by preparing a solution of 1.65 g BBCP1, 0.68 g polystyrene homopolymer (PS-HP), 0.68 g polylactide homopolymer (PLA-HP) and 7 g n-butyl acetate. The relative mass ratio of BBCP1 solids to the combined PS-HP and PLA-HP solids in TC2 was 55:45.

[0133] TC3 was obtained by preparing a solution of 1.50 g BBCP1, 0.75 g polystyrene homopolymer (PS-HP), 0.75 g polylactide homopolymer (PLA-HP) and 7 g n-butyl acetate. The relative mass ratio of BBCP1 solids to the combined PS-HP and PLA-HP solids in TC3 was 50:50.

[0134] TC4 was obtained by preparing a solution of 1.38 g BBCP1, 0.81 g polystyrene homopolymer (PS-HP), 0.81 g polylactide homopolymer (PLA-HP), and 7 g n-butyl acetate. BC1 had a solids content of 30 wt.-%. The relative mass ratio of BBCP1 solids to the combined PS-HP and PLA-HP solids in TC4 was 46:54.

[0135] TC5 was obtained by preparing a solution of 1.20 g BBCP1, 0.90 g polystyrene homopolymer (PS-HP), 0.90 g polylactide homopolymer (PLA-HP) and 7 g n-butyl acetate. The relative mass ratio of BBCP1 solids to the combined PS-HP and PLA-HP solids in TC5 was 40:60.

[0136] The polystyrene homopolymer (PS-HP) used had an M n The polylactide homopolymer (PLA-HP) used had an M n had the following characteristics:

[0137] 2.2 Topcoat compositions TC1a to TC5a and TC4a2 Dilution compositions of TC1 to TC5 were prepared. TC1a was obtained by mixing 85 pbw (parts by mass) of TC1 with 15 pbw of n-butyl acetate. TC2a was obtained by mixing 85 pbw (parts by mass) of TC2 with 15 pbw of n-butyl acetate. TC3a was obtained by mixing 85 pbw (parts by mass) of TC3 with 15 pbw of n-butyl acetate. TC4a was obtained by mixing 85 pbw (parts by mass) of TC4 with 15 pbw of n-butyl acetate. TC5a was obtained by mixing 85 pbw (parts by mass) of TC5 with 15 pbw of n-butyl acetate.

[0138] Further dilution compositions of TC4 were prepared: TC4a2 was obtained by mixing 90 pbw (parts by weight) of TC4 with 10 pbw of n-butyl acetate.

[0139] 2.3 Topcoat compositions TC1b to TC5b Topcoat composition TC1b was obtained by mixing 85 pbw (parts by mass) of TC1 with 15 pbw of R10CG392A. Topcoat composition TC2b was obtained by mixing 85 pbw (parts by mass) of TC2 with 15 pbw of R10CG392A. Topcoat composition TC3b was obtained by mixing 85 pbw (parts by mass) of TC3 with 15 pbw of R10CG392A. Topcoat composition TC4b was obtained by mixing 85 pbw (parts by mass) of TC4 with 15 pbw of R10CG392A. Topcoat composition TC5b was obtained by mixing 85 pbw (parts by mass) of TC5 with 15 pbw of R10CG392A.

[0140] R10CG392A is a commercially available 1K high solids clearcoat composition. R10CG392A was mixed into each of the topcoats, in each case under stirring.

[0141] 2.4 Topcoat compositions TC4c95, TC4c90, TC4c85, TC4c80, TC4c75 and TC4c70 Topcoat composition TC4c95 was obtained by mixing 95 pbw (parts by weight) of TC4 with 5 pbw of R10CG392A. Topcoat composition TC4c90 was obtained by mixing 90 pbw (parts by weight) of TC4 with 10 pbw of R10CG392A. Topcoat composition TC4c85 was obtained by mixing 85 pbw (parts by weight) of TC4 with 15 pbw of R10CG392A. Topcoat composition TC4c80 was obtained by mixing 80 pbw (parts by weight) of TC4 with 20 pbw of R10CG392A. Topcoat composition TC4c75 was obtained by mixing 75 pbw (parts by weight) of TC4 with 25 pbw of R10CG392A. Topcoat composition TC4c70 was obtained by mixing 70 pbw (parts by weight) of TC4 with 30 pbw of R10CG392A. Each of the topcoat compositions was prepared by adding R10CG392A to TC4 under stirring.

[0142] 2.5 Topcoat Compositions TC4-CC1, TC4-CC2, TC4-CC3, TC4-CC4 and TC4-CC5 Topcoat composition TC4-CC1 was obtained by mixing 84.7 pbw (parts by weight) of TC4 with 15.3 pbw of R10CG392D, which is a commercially available 1K clearcoat composition. Topcoat composition TC4-CC2 was obtained by mixing 84.4 pbw (parts by weight) of TC4 with 15.6 pbw of R10CG062T, which is a commercially available Uregloss CW® 1K clearcoat composition. TC4-CC3 was obtained by mixing 83.9 pbw (parts by weight) of TC4 with 16.1 pbw of E126CG300, which is a commercially available Stargloss® 1K clearcoat composition. TC4-CC4 was obtained by mixing 85.4 pbw (parts by weight) of TC4 with 14.6 pbw of a commercially available 2K Progloss® clear coat composition. The 2K clear coat composition was in turn prepared by mixing 1 pbw of its B component (N52CG081) with 3.75 pbw of its A component (E10CG081G). TC4-CC5 was obtained by mixing 84.8 pbw (parts by weight) of TC4 with 15.2 pbw of a commercially available 2K iGloss® clear coat composition. The 2K clear coat composition was in turn prepared by mixing 1 pbw of its B component (N52CG500) with 1 pbw of its A component (E10CG500B).

[0143] 3. Manufacturing of multi-layer coating systems Steel panels with a cured primer coat were used as substrates. A commercially available black basecoat (E487KU414T Agate Black or E387KU343C Shadow Black) was spray applied as a basecoat over the primer coat and cured at about 129°C (265°F) for 25 minutes. The resulting dry film layer thickness of the black basecoat was in the range of about 16.5 μm to 19.0 μm (0.65 to 0.75 mils). Then, one of the topcoat compositions TC1-TC5, TC1a-TC5a, TC4a2, TC1b-TC5b, TC4c95-TC4c70, and TC4-CC1, TC4-CC2 and TC4-CC5 was applied as a topcoat composition onto the cured basecoat film by a drawdown bar using a 200 μm gap on a standard drawdown bar applicator available from Byk in an amount that would result in a dry film layer thickness of 27-54 μm after subsequent baking. After application of the topcoat composition, it was flashed off at room temperature (23° C.) for up to 10 minutes, and then baked at about 140° C. (285° F.) or about 130° C. (265° F.) for 30 minutes, or dried at 24° C. (75° F.) for 24 hours.

[0144] 4. Properties of substrates coated with multilayer coating systems Each resulting coated substrate, as outlined in item 3, was analyzed for its color values ​​L* and C* and its R f value and λ max The measurements of these values ​​were carried out according to the method disclosed in the "Methods" section. The measured values ​​are shown in Tables 1 to 8. C* 平均 is the C* value obtained by dividing the sum of the C* values ​​measured at 15°, 45° and 110° by 3.

[0145] [Table 1]

[0146] [Table 2]

[0147] [Table 3]

[0148] The data presented in Tables 1-3 demonstrate that application of a BBCP1-containing topcoat over a cured basecoat film results in improved color (increased chroma C * Table 1 shows that good chroma values ​​can be obtained when baking is performed at 130° C. Even better values ​​are obtained when drying is used. The observation that very good chroma values ​​are obtained when drying is used is also evident from Tables 2 and 3. It is particularly evident from Table 3 that a stronger shift from red to green appearance is observed, increasing when going from TC1a to TC5a, which is often desirable.

[0149] [Table 4]

[0150] [Table 5]

[0151] [Table 6]

[0152] The data presented in Tables 4-6 show that the application of a BBCP1-containing topcoat over a cured basecoat film resulted in improved color, especially in terms of increased chroma C * It is apparent from Tables 5 and 6 in particular that a strong blue to UV shift is observed, which is often desirable.

[0153] [Table 7]

[0154] The data presented in Table 7 demonstrates that the color and blue appearance was retained in all cases.

Claims

1. At least two coating layers L1 and L2, which are optionally present on the precoated substrate and are different from each other, i.e. a first coating layer L1 applied over at least a portion of the optionally precoated substrate; and A topcoat layer as a second coating layer L2 applied over the first coating layer L1 A multi-layer coating system comprising: the first coating layer L1 is a pigmented coating layer, The topcoat layer L2 is formed from a coating composition comprising at least one block copolymer containing a main chain and at least two blocks B1 and B2 that are different from each other; the main chain of the copolymer contains an ethylenically unsaturated carbon-carbon double bond and is obtained by ring-opening metathesis polymerization (ROMP) with a cyclic ethylenically unsaturated monomer; 1. A multi-layer coating system, characterized in that the block B1 comprises at least one type of side chain S1 attached to the main chain, the block B2 comprises at least one type of side chain S2 attached to the main chain, different from the side chain S1, each of the side chains S1 comprises at least one polymer moiety M1 selected from the group consisting of polyester, polyether and poly(meth)acrylate moieties, and each of the side chains S2 comprises at least one polymer moiety M2 different from the polymer moiety M1 and selected from the group consisting of polyester, poly(meth)acrylate, polyether, polysiloxane and polystyrene moieties.

2. 2. The multi-layer coating system of claim 1, wherein the first coating layer L1 is capable of absorbing at least those wavelengths that are not reflected by the topcoat layer L2.

3. 3. The multi-layer coating system according to claim 1, wherein the top coat layer L2 is a clear coat layer formed from a clear coat composition.

4. 4. A multilayer coating system according to claim 1, characterized in that the first and second coating layers L1 and L2 are located adjacent to one another.

5. C* of at least 40 平均 value, and said C* 平均 5. A multilayer coating system according to claim 1, characterized in that the value is the sum of the C* values ​​(chroma values ​​according to the L*C*h color model) measured at angles of 15°, 45° and 110° divided by 3.

6. 6. The multilayer coating system according to claim 1, characterized in that at least the applied coating composition comprising at least one block copolymer used for the production of the topcoat layer L2 is obtained by a process in which the topcoat layer L2 of the multilayer coating system is cured or dried, the curing meaning chemical curing at room temperature or at elevated temperature, and the drying meaning physical drying (non-chemical curing) at room temperature or at elevated temperature.

7. A multi-layer coating system according to any one of claims 1 to 6, characterized in that the cyclic ethylenically unsaturated monomer is a cyclic olefinic monomer.

8. Each of the side chains S1 of the first block B1 of the copolymer comprises at least one polymer moiety M1 containing at least one hydroxyl group, the polymer moiety M1 being selected from the group consisting of aliphatic polyester moieties and aliphatic polyether moieties, and each of the side chains S2 of the second block B2 of the copolymer comprises at least one polymer moiety M2 that does not contain both a hydroxyl group and a carboxylic acid group, the polymer moiety M2 being selected from the group consisting of polyether, polysiloxane and polystyrene moieties, A multi-layer coating system according to any one of claims 1 to 7.

9. At least one copolymer has a number average molecular weight (M ｎ 9. The multi-layer coating system according to claim 1, characterized in that it comprises:

10. the first block B1 of the copolymer comprises at least one structural unit SU1a and optionally at least one structural unit SU1b, the structural unit SU1a being represented by at least one of the partial structures PS1a-1 and PS1a-2, the optionally present structural unit SU1b being represented by the partial structure PS1b, 【Chemistry 1】 wherein, independently of each other, The parameter x is in the range of 1 to 1000; The parameter a is in the range of 0 to 1000. the relative ratio of parameter x to parameter a is in the range of 1:0 to 1:3; Mx, J １ and G are each independently CH ２ or C=O, Q represents a divalent alkyl, heteroalkyl, cycloalkyl, heterocycloalkyl, aryl, or heteroaryl residue; Rx represents a side chain S1 comprising a polymer moiety M1; R １ is C １ ~C ６ -represents an alkyl residue] and the second block B2 of the copolymer comprises at least one structural unit SU2a and optionally at least one structural unit SU2b, the structural unit SU2a being represented by at least one of the partial structures PS2a-1 and PS2a-2, the optionally present structural unit SU2b being represented by the partial structure PS2b, 【Chemistry 2】 wherein, independently of each other, The parameter y is in the range of 1 to 1000; The parameter b is in the range of 0 to 1000. the relative ratio of parameter y to parameter b is in the range of 1:0 to 1:3; My, J ２ and G are each independently CH ２ or C=O, Q represents a divalent alkyl, heteroalkyl, cycloalkyl, heterocycloalkyl, aryl, or heteroaryl residue; Ry represents a side chain S2 comprising a polymer moiety M2; R ２ is C １ ~C ６ -represents an alkyl residue] Characterized in that 10. A multi-layer coating system according to any one of claims 1 to 9.

11. A multilayer coating system according to claim 1, characterized in that all structural units present in a first block B1 of the copolymer are randomly arranged in block B1 and / or all structural units present in a second block B2 of the copolymer are randomly arranged in block B2.

12. The parameter x is in the range of 1 to 750; The parameter a is in the range of 1 to 750; The relative ratio of parameter x to parameter a is in the range of 2:1 to 1:2; Rx represents C2-C6-alkylene-O-[C(═O)-C2-C6-alkylene-O]n-H, where the parameter n is in the range of 1 to 500, R 1 represents an unbranched C 1 -C 6 -alkyl residue, The parameter y is in the range of 1 to 750; Parameter b is in the range of 1 to 750; the relative ratio of parameter y to parameter b is in the range of 2:1 to 1:2; Ry represents C 1 -C 8 -alkylene-ZT, where Z represents C(═O)—O or a divalent N-containing heterocyclic residue and T represents a C 1 -C 4 -alkylene residue to which a polystyrene moiety is attached; 12. A multilayer coating system according to claim 1, characterized in that R 2 represents a branched C 1 -C 6 -alkyl residue.

13. 13. The multilayer coating system according to any one of claims 1 to 12, characterized in that at least one copolymer is present in the coating composition used to produce the top-coat layer L2 in an amount ranging from 10 to 100 wt.-% relative to the total solids content of the coating composition.

14. 14. The multilayer coating system according to claim 1, characterized in that the coating composition used to produce the topcoat layer L2 further comprises at least one homopolymer.

15. The multi-layer coating system of claim 14, wherein the at least one homopolymer has a number average molecular weight (M n ) that is at least 100 times lower than the number average molecular weight (M n ) of the at least one copolymer.

16. The multi-layer coating system of claim 14 or 15, wherein the relative weight ratio of copolymer solids to at least one homopolymer solids in the coating composition is in the range of 99:1 to 5:

95.

17. 17. A multilayer coating system according to any one of claims 1 to 16, characterized in that the coating composition used to produce the top-coat layer L2 comprises, besides the copolymer and, if present, besides the at least one homopolymer according to any one of claims 14 to 16, at least one further resin, and the relative weight ratio of copolymer solids to the solids of the at least one further resin in the coating composition is in the range of from 5:95 to 100:

0.

18. A method for producing a multi-layer coating system according to any one of claims 1 to 17, comprising at least steps (1), (2) and (3), i.e. (1) applying a pigmented basecoat composition to at least a portion of an optionally precoated substrate to form a first coating film on at least a portion of the optionally precoated substrate; (2) applying a top coat composition, which comprises at least one block copolymer and is different from the base coat composition applied in step (1), to the first coating film present on the substrate obtained after step (1) to form a second coating film; (3) curing or drying at least the second coating film applied in step (2), and optionally also the first coating film applied in step (1), if said first coating film was not cured or dried before carrying out step (2), to obtain a multi-layer coating system comprising at least a first and a second coating layer L1 and L2. A method comprising:

19. A coated substrate obtainable by the method of claim 18.

20. 18. Use of a coating composition comprising at least one block copolymer according to any one of claims 1 to 17 for improving the color intensity of a multi-layer coating system according to any one of claims 1 to 17.

21. The use of claim 20 for increasing the C* average saturation value of a coating composition comprising at least one block copolymer according to any one of claims 1 to 17 to at least 40.

22. The method of use described in claim 21, wherein the C* average saturation value is the sum of the C* values ​​(saturation values ​​according to the L*C*h color model) measured at angles of 15°, 45° and 110° divided by 3.

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