Multi-layer coating systems obtained from block copolymer-containing basecoat compositions

Abstract

The present invention relates to a multilayer coating system comprising at least three distinct coating layers L1, L2, and L3 on a substrate: a first coating layer L1 comprising a platelet-shaped pigment applied over at least a portion of the substrate; a second coating layer L2 applied over the first coating layer L1; and a third coating layer L3 applied over the second coating layer L2, wherein the second coating layer L2 is formed from a coating composition comprising at least one block copolymer containing a main chain, at least two blocks B1 and B2, and side chains S1 and S2 comprising different polymer moieties M1 and M2. The present invention also relates to a method for preparing the multilayer coating system, a coated substrate obtainable therefrom, and a method for using the coating composition comprising the block copolymer to improve, in particular increase, the chromaticity of the multilayer coating system of the present invention.

Description

[Technical Field]

[0001] The present invention relates to a multilayer coating system comprising at least three different coating layers L1, L2, and L3 on a substrate, namely, a first coating layer L1 comprising a platelet-shaped pigment applied over at least a portion of the substrate, a second coating layer L2 applied over the first coating layer L1, and a third coating layer L3 applied over the second coating layer L2, wherein the second coating layer L2 is formed from a coating composition comprising at least one block copolymer containing a main chain, at least two blocks B1 and B2, and side chains S1 and S2 comprising different polymer moieties M1 and M2. The present invention also relates to a method for preparing the multilayer coating system and to a coated substrate obtainable therefrom. [Background technology]

[0002] In a typical automotive coating process, multiple layers are typically applied to the surface of a suitable substrate, such as a metal substrate, in the form of a multi-layer coating system: for example, an electrodeposition coat (e-coat), optionally a primer, one or two base coats, and a top coat, particularly a clear coat, as the outermost layer, in that order. At least an e-coat layer is typically applied to the substrate surface and then cured before further coatings are applied thereon. After applying and curing at least an electrodeposition coating film, and optionally after applying a primer, at least one (first) base coat formulation, usually pigmented, is applied. 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 typically applied, where at least the base coat and top coat are now typically applied using a wet-on-wet application. The coated substrate is then passed through an oven at a temperature that simultaneously cures at least the base coat(s) and the top coat, such as a clear coat. Optionally, if a primer coat is present, the base coat(s) and top coat, particularly the clear coat, are also cured at this stage.

[0003] Multilayer coatings used in the automotive industry have a significant number of requirements that must be met and / or must be satisfied, not only due to regulations but also due to quality standards set by the automotive industry. Therefore, multilayer coatings must exhibit many desired properties, at least to a sufficient extent, to meet these requirements. For example, it is desirable to avoid optical defects. Furthermore, it is particularly desirable to achieve excellent coloring properties of the multilayer coating.

[0004] Multilayer coatings comprising at least two coating layers are disclosed, for example, in WO 2020 / 160299 A1. The first layer is a photonic crystal film comprising a pigment and a block copolymer. The second layer, present on the first layer, is used as a topcoat and is an optical adhesive or UV-curable resin. The block copolymer, together with at least one pigment, is always present in the first layer. WO 2020 / 160299 A1 aims to provide multilayer coatings with good transparency in the visible spectrum. Coating compositions used to prepare such colored photonic crystal films are further disclosed in WO 2020 / 180427 A1, but multilayer coatings, much less those prepared by wet-on-wet techniques, are not disclosed therein.

[0005] Because multilayer coatings known in the art do not always exhibit sufficiently good color properties, for example, with respect to brightness, and particularly with respect to chroma, there is a need to provide cured coatings and coating systems that exhibit improved color properties and color values, particularly with respect to their chroma and the achievement of excellent chroma values, compared to coatings and coating systems known in the prior art. However, in addition, there is a need to improve color transition properties, especially for effect pigment-containing multilayer coatings that utilize platelet-shaped effect pigments in the base coat layer. Furthermore, these cured coatings and coating systems should be prepared in an economically advantageous manner with respect to the shortest possible process times, including the shortest possible curing times, especially when these coatings and coating systems are used in automotive OEM production. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] WO 2020 / 160299 A1 [Patent Document 2] WO 2020 / 180427 A1 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, compared to coatings and coating systems known from the prior art, exhibit improved color properties and color values, in particular with regard to their color intensity and the achievement of excellent saturation values, and at the same time exhibit unique color transitions, and which can be prepared in an economically advantageous manner, in particular with regard to the shortest possible process times, including the shortest possible curing times, especially when these multi-layer coating systems are used in automotive OEM production. [Means for solving the problem]

[0008] This object has been solved by the subject matter of the present claims and the preferred embodiments thereof disclosed herein, ie the subject matter described herein.

[0009] The first subject of the present invention is a coating layer comprising at least three coating layers L1, L2 and L3, which are present on an optionally precoated substrate and which are different from one another, namely a first coating layer L1 comprising at least one platelet-shaped pigment applied over at least a portion of the optionally precoated substrate; a second coating layer L2 applied over the first coating layer L1; and A third coating layer L3 applied over the second coating layer L2 1. A multi-layer coating system comprising: the second coating 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 one another, wherein block B1 comprises at least one side chain S1 attached to the main chain, block B2 comprises at least one side chain S2 attached to the main chain and different from side chain S1, each side chain S1 comprising at least one polymer moiety M1 selected from the group consisting of polyester, polyether and poly(meth)acrylate moieties, and each side chain S2 comprising 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.

[0010] A further subject of the present invention is a method for producing a medicament comprising at least steps (1), (2), (3) and (4), i.e. (1) applying to at least a portion of an optionally precoated substrate a first basecoat composition comprising at least one platelet-shaped pigment to form a first coating film on at least a portion of the optionally precoated substrate; (2) applying a second base coat composition, which comprises at least one block copolymer as defined for the multi-layer coating system and is different from the first 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, the second coating film preferably being adjacent to the first coating film; (3) applying a coating composition different from the compositions applied in steps (1) and (2) to the second coating film present on the substrate obtained after step (2), preferably forming a third coating film adjacent to the second coating film, said coating composition preferably being a clearcoat composition; and (4) simultaneously curing at least the second and third coating films applied in steps (2) and (3), and optionally the first coating film applied in step (1) if said first coating film has not been cured prior to performing step (2), to obtain a multi-layer coating system comprising at least first, second, and third coating layers L1, L2, and L3. a method for preparing the multi-layer coating system of the present invention, comprising:

[0011] A further subject of the invention are coated substrates obtainable by the process according to the invention.

[0012] The block copolymers used in the present invention are also referred to hereinafter as brush block copolymers (BBCPs).

[0013] Furthermore, it has been found, particularly surprisingly, that multi-layer coating systems can be produced in an economically advantageous manner with regard to short process times and short cure times, especially when these coatings and coating systems are used in automotive OEM production.

[0014] It has been particularly surprisingly found that the aforementioned advantageous effects are the result of incorporating a block copolymer BBCP into a coating composition and using said coating composition as a midcoat composition (second basecoat composition) when preparing the multi-layer coating system of the present invention. Even more surprisingly, it has been found that these effects can be observed in a particularly advantageous manner when a specific wet-on-wet application is used to prepare the multi-layer coating system, in which the applied coating composition comprising at least one block copolymer BBCP used to prepare the second coating layer L2 and the applied coating composition used to prepare the third coating layer L3 are cured simultaneously, i.e., cured simultaneously, to obtain the second coating layer L2 and the third coating layer L3 of the multi-layer coating system. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 illustrates a multi-layer coating system of the present invention comprising layers L1, L2, and L3 overlying a substrate S precoated with a primer P. [Figure 2]Figure 2 shows the multi-angle (observation angles: -15°, +15°, +25°, +45°, +75°, +110°) measurement geometry. DETAILED DESCRIPTION OF THE INVENTION

[0016] The term "comprises" in the sense of the present invention, for example in connection with the coating compositions used in the method of the present invention or for preparing the multi-layer coating system of the present invention, preferably has the meaning of "consists of." For example, with respect to the second base coat composition, in addition to all essential components present therein, one or more further components specified below and optionally included therein may also be included therein. All components may in each case be present in their preferred embodiments, as specified below.

[0017] The proportions and amounts in wt.-% (mass %) of any of the components shown below present in each coating composition are in each case based on the total weight of the respective composition and add up to 100 mass %.

[0018] Each of the coating compositions used in steps (1), (2), and (3) of the method of the present invention and / or used to prepare the coating layers L1, L2, and L3 may contain, in addition to the components outlined in more detail below, one or more commonly used additives depending on the desired application. For example, each of the coating compositions may independently contain at least one additive selected from the group consisting of reactive diluents, catalysts, light stabilizers, antioxidants, defoamers, emulsifiers, slip additives, polymerization inhibitors, plasticizers, free-radical polymerization initiators, adhesion promoters, flow control agents, film-forming aids, sag control agents (SCAs), flame retardants, corrosion inhibitors, drying agents, thickeners, biocides, and / or matting agents. These may be used in known and conventional proportions. Preferably, the content thereof based on the total mass of each coating composition is 0.01 to 20.0 mass%, more preferably 0.05 to 15.0 mass%, particularly preferably 0.1 to 10.0 mass%, most preferably 0.1 to 7.5 mass%, particularly 0.1 to 5.0 mass%, and most preferably 0.1 to 2.5 mass%.

[0019] In the method of the present invention, particularly in each of steps (1) to (3), and / or each of the coating compositions used to prepare the multi-layer coating system, can be aqueous (water-borne) or organic solvent-based (solvent-borne, non-aqueous).

[0020] For the purposes of the present invention, the terms "solvent-borne" or "non-aqueous" are preferably understood to mean that organic solvent(s) are present as solvent(s) and / or diluent(s) in the respective coating composition, e.g., if the respective coating composition is solvent-borne, as the major constituent of all solvents and / or diluents present in the second basecoat composition applied in step (2) of the inventive method. Preferably, the organic solvent(s) are present in an amount of at least 35% by weight, based on the total weight of the coating composition. Solvent-borne coating compositions preferably contain at least 40% by weight, more preferably at least 45% by weight, and very preferably at least 50% by weight of organic solvent(s) fraction, in each case based on 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 March 11, 1999. Examples of such organic solvents include heterocyclic, aliphatic, or aromatic hydrocarbons, monohydric or polyhydric alcohols, especially methanol and / or ethanol, ethers, esters, ketones, and amides, such as N-methylpyrrolidone, N-ethylpyrrolidone, dimethylformamide, toluene, xylene, butanol, ethyl glycol and butyl glycol and their acetates, butyl diglycol, diethylene glycol dimethyl ether, cyclohexanone, methyl ethyl ketone, methyl isobutyl ketone, acetone, isophorone, or mixtures thereof. The solvent-borne coating composition preferably does not contain or essentially does not contain water. The term "essentially" in this context preferably means that water is not intentionally added when preparing the coating composition.

[0021] The term "waterborne" or "aqueous" is understood for the purposes of the present invention to mean that water is present as the major constituent of all solvents and / or diluents present in an aqueous coating composition, e.g., the first basecoat composition applied in step (1) of the inventive method. Preferably, water is present in an amount of at least 35% by weight, based on the total weight of the coating composition. The aqueous coating composition preferably comprises a water fraction of at least 40% by weight, more preferably at least 45% by weight, and very preferably at least 50% by weight, in each case based on the total weight of the coating composition. The proportion of organic solvent(s) is preferably <20% by weight, more preferably in the range of 0 to <20% by weight, and very preferably in the range of 0.5 to 20% by weight, or 17.5% by weight, or 15% by weight, or 10% by weight, in each case based on the total weight of the coating composition.

[0022] Unless otherwise defined in the present invention, polymer-specific terms are used in accordance with the International Union of Pure and Applied Chemistry Recommendations 2008, published by the Polymer Division of IUPAC and published in the Handbook of Polymer Chemistry Terminology and Nomenclature (RSC Publishing, © 2009, ISBN: 978-0-85404-491-7).

[0023] Coating-specific terms are used in accordance with DIN EN ISO 4618 (German edition, date: March 2007) if not otherwise defined in the present invention.

[0024] The multi-layer coating system of the present invention The multilayer coating system of the present invention comprises at least three coating layers L1, L2 and L3 present on an optionally precoated substrate and which differ from one another as defined above.

[0025] Preferably, at least the second coating layer L2 and the third coating layer L3 are disposed adjacent to one another. More preferably, the first coating layer L1 and the second coating layer L2 are also disposed adjacent to one another. Most preferably, the first, second and third coating layers L1, L2 and L3 are disposed adjacent to one another, and the coating layers L1 and L2 are at least partially transparent to visible light.

[0026] Preferably, the multi-layer coating system can be obtained by a method in which at least an applied coating composition comprising at least one block copolymer BBCP used to prepare the second coating layer L2 and an applied coating composition used to prepare the third coating layer L3 are cured simultaneously to obtain the second coating layer L2 and the third coating layer L3 of the multi-layer coating system.

[0027] Curing is preferably selected from chemical curing such as chemical crosslinking, radiation curing, and / or physical drying (non-chemical curing), in each case at room temperature or at an elevated temperature, more preferably selected from chemical curing such as chemical crosslinking, and / or physical drying (non-chemical curing), in each case at room temperature or at an elevated temperature, in each case preferably the minimum curing temperature applied for curing is 80°C.

[0028] Base material The multi-layer coating system of the present invention is particularly suitable as a coating for automotive bodies or parts thereof, including respective metal substrates, but also for plastic substrates, such as polymeric substrates. Accordingly, the preferred substrate is an automotive body or part thereof.

[0029] Suitable metal substrates for use in accordance with the present invention include all substrates commonly used and known to those skilled in the art.The substrates used in accordance with the present invention are preferably metal substrates, more preferably steel, preferably bare steel, cold-rolled steel (CRS), hot-rolled steel, galvanized steel such as hot-dip galvanized steel (HDG), alloy galvanized steel (e.g., Galvalume, Galvanal, or Galfan), aluminized steel, aluminum and magnesium, and also Zn / Mg alloys and Zn / Ni alloys.A particularly suitable substrate is a part of an automobile body or a complete automobile body for production.

[0030] Preferably, thermoplastic polymer and thermosetting polymer are used as plastic substrate.Suitable polymer includes polyester, polyamide, polyolefin, such as polyethylene, polypropylene, polystyrene, and also polybutadiene, polyacrylonitrile, polyacetal, polyacrylonitrile-ethylene-propylene-diene-styrene copolymer (A-EPDM), ASA (acrylonitrile-styrene-acrylic acid ester copolymer) and ABS (acrylonitrile-butadiene-styrene copolymer), polyetherimide, phenolic resin, urea resin, melamine resin, alkyd resin, epoxy resin, polyurethane, such as TPU, polyether ketone, polyphenylene sulfide, polyether, polyvinyl alcohol, and their mixtures. Polycarbonates and poly(meth)acrylates are particularly preferred.

[0031] The substrates used in accordance with the present invention are preferably metal substrates that have been pretreated with at least one conversion coating composition, such as a metal phosphate-containing composition, such as a zinc phosphate-containing composition, and / or with an oxalate. This type of phosphating pretreatment is typically carried out after the substrate has been cleaned and before the substrate is electrocoated, and is a common pretreatment step, particularly in the automotive industry.

[0032] As outlined above, the substrate used may be a precoated substrate, i.e., a substrate bearing at least one cured coating film. The substrate may be precoated with a cured electrodeposition coating layer. The substrate may additionally or alternatively comprise at least one cured or uncured primer coating film, for example, as at least one additional precoat. The term "primer" is known to those skilled in the art. A primer is typically applied after providing a cured electrodeposition coating layer on the substrate. If a cured primer coating film is present, the cured electrodeposition coating film is present below, and preferably adjacent to, the cured primer coating film. This primer curing is preferably carried out at a temperature in the range of 40 to 140°C, and may particularly include a "low bake" step at a temperature in the range of 80 to 100°C. As outlined above, substrates bearing an uncured primer coating film may also be used, particularly substrates such as metal substrates bearing a cured electrodeposition coating film on which the uncured primer coating film is present. Thus, a primer composition can be applied to an optionally precoated substrate to form a primer coating film on the optionally precoated substrate, followed by an optional curing step. The coating composition used to form the first coating layer L1 can then be applied before or after curing the primer coating film, optionally after a flash-off period, such as a flash-off period of 1 to 20 minutes, preferably at a temperature not exceeding 40°C, for example, in the range of 18 to 30°C.

[0033] Coating layer L1 and first base coat composition used to form it A first coating layer L1 comprising at least one platelet-shaped pigment is applied onto at least a portion of the optionally precoated substrate, so 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 coating layer L1 is at least partially reflective, but even more preferably also at least partially absorbing, wavelengths that are not reflected by the second layer L2.

[0035] The first coating layer L1 is formed from a pigmented coating composition comprising at least one platelet-shaped pigment and preferably also at least one non-platelet-shaped, preferably absorbing pigment. Such a coating composition is also referred to herein as a first basecoat composition. This composition is the composition used in step (1) of the method of the present invention.

[0036] The first base coat composition is preferably an aqueous, i.e., water-borne coating composition, or a solvent-borne base coat composition. In particular, it is a solvent-borne base coat composition. The first base coat composition can 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 Römpp Lexikon, paint and printing inks, Georg Thieme Verlag, 1998, 10th edition, page 57. Base coats are therefore used in particular in automotive painting and general industrial painting to impart color and / or optical effects by using the base coat as an intermediate coating composition.

[0038] pigment The first base coat composition is pigmented. The term "pigment" is known to those skilled in the art, for example from DIN 55943 (date: October 2001). "Pigment" in the sense of the present invention preferably refers to a particulate, e.g., powder or platelet, colorant and / or optical effect-providing component that is substantially, preferably completely, insoluble in the medium that surrounds it, e.g., one of the coating compositions used in the present invention. Pigments preferably differ from "fillers" in their refractive index, which is ≧1.7. The term "filler" is known to those skilled in the art, for example from DIN 55943 (date: October 2001). Pigments may be inorganic or organic.

[0039] Platelet Pigments The first base coat composition comprises at least one platelet-shaped pigment. The term "platelet-shaped pigment" as used in the coatings field refers to platelet-shaped metallic effect pigments and so-called platelet-shaped special effect pigments. These special effect pigments are generally classified as pearlescent pigments and interference pigments.

[0040] Platelet pigments as used herein preferably have a number average platelet thickness h in the range of 30 nm to 1 μm. 50 , and preferably an average platelet diameter D in the range of 5 μm to 40 μm 50 and therefore the aspect ratio D 50 / h 50 is preferably in the range of about 5:1 to about 1300:1. 50 is the volume-based mean particle size measured using a laser diffraction particle analyzer, e.g., a Malvern Mastersizer 3000 (available from Malvern Panalytical, Ltd., UK), and h 50 is the average grain thickness. Average thickness h 50 h constitutes the value at which 50% of the platelet pigments are below the specified thickness when at least 100 pigments, e.g., 100 pigments, are measured in the cumulative frequency distribution, also called the cumulative pass curve. 50The value of can be determined by preparing a cured coating containing the pigment. It is important to achieve as good an orientation of the flakes as possible in the application medium. After this, the cured coating is partially polished and its cross section is observed under an electron microscope (SEM or TEM, both are equivalent for the purposes of this invention). Only particles showing a preferred orientation are counted.

[0041] Among platelet-shaped metal effect pigments, platelets made of single metals or their alloys can be employed. Such metal effect pigments are typically aluminum, zinc-copper, copper, nickel, or steel platelets, with aluminum and copper platelets being most preferred, and aluminum platelets being particularly preferred. Typical platelet shapes, particularly in the case of aluminum pigments, are the so-called silver dollar and cornflake shapes. Very thin metal effect pigments are, for example, PVD pigments (i.e., physical vapor deposition pigments). Platelet-shaped metal effect pigments can be surface-modified, i.e., modified or coated with inorganic or organic compounds. Such modifications can be oxidation of the pigment surface, metal oxide coating, or organic coating with organosilanes or organic colorants.

[0042] Among the platelet-shaped special effect pigments, coated platelets can be used, in particular those selected from mica, silica, alumina, glass and borosilicate. The coating of the platelets of the type mentioned above can be a non-absorbing coating, such as a coating comprising or consisting of TiO2 (rutile), TiO2 (anatase), ZrO2, SnO2 and SiO2; or a selectively absorbing coating, such as FeOOH, Fe2O3, Cr2O3, TiO 2-x , TiO x N y , KFe[Fe(CN)6], or a colorant coating.

[0043] Further platelet-shaped special effect pigments are pearlescent pigments that do not contain a platelet-shaped substrate, such as natural pearl essence, basic lead carbonate, bismuth oxychloride, finely divided iron oxide, and titanium dioxide flakes.

[0044] Depending on whether the first basecoat composition is solvent-borne or water-based, an aqueous or non-aqueous pigment paste comprising at least one platelet-shaped pigment is preferably used to prepare the first basecoat composition.

[0045] The amount of platelet-shaped effect pigments for use according to the invention in the coating composition can vary widely and is guided on the one hand by the opacity of the effect pigments and on the other hand by the intensity of the optical effect that one wishes to obtain. Preferably, the first base coat composition according to the invention comprises 0.5 to 12.5% ​​by weight, more preferably 1.0 to 10.0% by weight, most preferably 2.0 to 6.0% by weight of one or more platelet-shaped pigments, based on the total weight of the coating composition.

[0046] Non-platelet pigments Preferably, the first base coat composition further comprises at least one visible light (wavelength 380 to 750 nm) absorbing non-platelet pigment, more preferably at least one black pigment and / or colored pigment, most preferably at least one black pigment, in particular at least one inorganic black pigment and / or at least one organic black pigment.

[0047] If at least one organic black pigment is present in the first base coat composition, it is preferably at least one perylene black pigment, such as Pigment Black 31 or Pigment Black 32. The most preferred black organic pigment is Perylene Black PB32. If at least one inorganic black pigment is present in the first base coat composition, it is preferably at least one carbon black pigment.

[0048] For the preparation of the first base coat composition, an aqueous or non-aqueous pigment paste containing at least one pigment is preferably used, depending on whether the first base coat composition is solvent-borne or water-based.

[0049] Preferably, therefore, the at least one non-platelet pigment preferably present in the first base coat composition is contained therein in an amount in the range of 0.1 to 25.0% by weight, more preferably 0.3 to 10.0% by weight, even more preferably 0.5 to 7.5% by weight, based on the total solids content of the first base coat composition.

[0050] binder The first base coat composition preferably comprises, besides at least one platelet-shaped pigment, at least one binder, more preferably at least one polymer (a1) as binder.

[0051] For the purposes of the present invention, the term "binder" is understood to mean a non-volatile component of a coating composition that is responsible for film formation, in accordance with DIN EN ISO 4618 (German edition, date: March 2007). This term also includes crosslinkers and additives when referring to non-volatile components. Therefore, the term "binder" does not encompass pigments and / or fillers contained therein. Preferably, at least one polymer (a1) is the main binder of the coating composition. The term "main binder" in the present invention preferably refers to the binder component that is present in a higher proportion, based on the total weight of the coating composition, when no other binder components are present in the coating composition.

[0052] The term "polymer" is known to those skilled in the art and, for the purposes of the present invention, includes polyadducts, polymerizations and polycondensations. The term "polymer" includes both homopolymers and copolymers.

[0053] Preferably, the first base coat composition does not include a copolymer BBCP such as is present in the coating composition used to form coating layer L2, and therefore preferably the first base coat composition does not include a polymer that is a copolymer BBCP.

[0054] At least one polymer used as component (a1) can be self-crosslinking or non-self-crosslinking.Suitable polymers that can be used are known from, for example, EP 0 228 003 A1, DE 44 38 504 A1, EP 0 593 454 B1, DE 199 48 004 A1, EP 0 787 159 B1, DE 40 09 858 A1, DE 44 37 535 A1, WO 92 / 15405 A1 and WO 2005 / 021168 A1.

[0055] 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 terms "(meth)acrylic" or "(meth)acrylate" in the context of the present invention include in each case the meanings "methacrylic" and / or "acrylic", or "methacrylate" and / or "acrylate".

[0056] Suitable polyurethanes are described, for example, in German patent application DE 199 48 004 A1, page 4, line 19 to page 11, line 29 (polyurethane prepolymer B1); German patent application DE 4437535 A1, Example D, page 7, line 55 to page 8, line 23; European patent application EP 0 228 003 A1, page 3, line 24 to page 5, line 40; European patent application EP 0 634 431 A1, page 3, line 38 to page 8, line 9; European patent application EP 0 574 417 B2, page 6, lines 24 to 41 and lines 45 to 47; European patent application EP 0 521 928 B1, page 9, lines 11 to 28; and International patent application WO 92 / 15405, page 2, line 35 to page 10, line 32.

[0057] Suitable polyethers are described, for example, in WO 2017 / 097642 A1 and WO 2017 / 121683 A1.

[0058] Preferred poly(meth)acrylates are described, for example, in EP 0569907 B1, page 12, line 41 to page 13, line 4, or in EP 0589340 B1, page 7, lines 10 to 21, and page 8, lines 3 to 16.

[0059] 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; EP 2421924 B1, page 16, line 50 to page 17, line 6; or 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 with a dendritic or star structure, as described, for example, in WO 2008 / 148555 A1.

[0060] Preferred polyurethane-poly(meth)acrylate copolymers (e.g. (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.

[0061] Preferred (meth)acrylic copolymers are OH-functional. Hydroxyl-containing monomers include hydroxyalkyl esters of acrylic or methacrylic acid, which 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 ε-caprolactone, and other hydroxyalkyl (meth)acrylates having branched or linear alkyl groups of about 10 carbons or less, and mixtures thereof. Hydroxyl groups on vinyl polymers, such as (meth)acrylic polymers, can also be generated by other means, such as ring-opening of glycidyl groups from copolymerized glycidyl methacrylate with organic acids or amines. Hydroxyl functionality may also be introduced through thioalcohol compounds, including, but not limited to, 3-mercapto-1-propanol, 3-mercapto-2-butanol, 11-mercapto-1-undecanol, 1-mercapto-2-propanol, 2-mercaptoethanol, 6-mercapto-1-hexanol, 2-mercaptobenzyl alcohol, 3-mercapto-1,2-propanediol, 4-mercapto-1-butanol, and combinations thereof. Any of these methods can be used to prepare useful hydroxyl-functional (meth)acrylic polymers.Examples of suitable comonomers that can be used include, but are not limited to, α,β-ethylenically unsaturated monocarboxylic acids containing 3 to 5 carbon atoms, such as acrylic acid, methacrylic acid, and crotonic acid, and alkyl and cycloalkyl esters, nitriles, and amides of acrylic acid, methacrylic acid, and crotonic acid; α,β-ethylenically unsaturated dicarboxylic acids containing 4 to 6 carbon atoms, and their anhydrides, monoesters, and diesters; vinyl esters, vinyl ethers, vinyl ketones, aromatic or heterocyclic aliphatic vinyl compounds. Representative examples of suitable esters of acrylic acid, methacrylic acid, and crotonic acid include, but are not limited to, esters formed by reaction with saturated aliphatic alcohols containing 1 to 20 carbon atoms, such as methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, tert-butyl, hexyl, 2-ethylhexyl, dodecyl, 3,3,5-trimethylhexyl, stearyl, lauryl, cyclohexyl, alkyl-substituted cyclohexyl, alkanol-substituted cyclohexyl, such as 2-tert-butyl and 4-tert-butylcyclohexyl, 4-cyclohexyl-1-butyl, 2-tert-butylcyclohexyl, 4-tert-butylcyclohexyl, 3,3,5,5-tetramethylhexyl, methyl esters ... Examples of suitable (meth)acrylic copolymers include methylcyclohexyl, tetrahydrofurfuryl, and isobornyl acrylate, methacrylate, and crotonate; unsaturated dialkanoic acids and anhydrides, such as fumaric acid, maleic acid, and itaconic acid, and their monoesters and diesters with alcohols such as methanol, ethanol, propanol, isopropanol, butanol, isobutanol, and tert-butanol, such as maleic anhydride, dimethyl maleate, and monohexyl maleate; vinyl acetate, vinyl propionate, vinyl ethyl ether, and vinyl ethyl ketone; styrene, α-methylstyrene, vinyltoluene, 2-vinylpyrrolidone, and p-tert-butylstyrene. (Meth)acrylic copolymers can be prepared by conventional techniques, for example, by heating the monomers in the presence of a polymerization initiator and, optionally, a chain transfer agent.

[0062] Suitable poly(meth)acrylates can also be prepared by multistage free-radical emulsion polymerization of olefinically unsaturated monomers in water and / or organic solvents. Examples of seed-core-shell polymers (SCS polymers) obtained in this way are disclosed in WO 2016 / 116299 A1. Preferred polyurethane-polyurea copolymers are polyurethane-polyurea particles, preferably having a Z-average particle size of 40 to 2000 nm, each of which in reacted form contains at least one isocyanate-containing polyurethane prepolymer containing anionic groups and / or groups that can be converted to anionic groups, and at least one polyamine containing two primary amino groups and one or two secondary amino groups. Preferably, such copolymers are used in the form of aqueous dispersions. In principle, such polymers can be prepared, for example, by conventional polyaddition of polyisocyanates with polyols and polyamines.

[0063] The polymer used as component (a1) preferably has a reactive functional group that allows for a crosslinking reaction. Any common crosslinkable reactive functional group known to those skilled in the art may be present. Preferably, the polymer used as component (a1) has at least one 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.

[0064] 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.

[0065] 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.

[0066] Furthermore, the first base coat composition may contain at least one typical crosslinking agent known per se. The crosslinking agent is included in the film-forming nonvolatile components of the coating composition and therefore falls within the general definition of "binder." Therefore, the crosslinking agent is included in component (a1).

[0067] Any conventional crosslinking agent can be used, including melamine resins, preferably melamine aldehyde resins, more preferably melamine formaldehyde resins, blocked polyisocyanates, polyisocyanates with free (unblocked) isocyanate groups, crosslinking agents with amino groups such as secondary and / or primary amino groups, crosslinking agents with epoxide and / or hydrazide groups, and crosslinking agents with carbodiimide groups, provided that the functional groups of the specific crosslinking agent are suitable for reacting with the crosslinkable functional groups of the film-forming polymer used as the binder in the crosslinking reaction. For example, a crosslinking agent with blocked isocyanate groups or free isocyanate groups can be reacted with a film-forming polymer with crosslinkable OH groups and / or amino groups at elevated temperatures for 1K formulations and at room temperature for 2K formulations. 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 aminoplast resins, melamine resins such as melamine formaldehyde resins are particularly preferred. Preferably, the melamine aldehyde resin, preferably the melamine formaldehyde resin, has at least one of an imino group, an alkylol group, and an etherified alkylol group as a functional group reactive with the functional groups of the binder to be crosslinked. An example of an alkylol group is a methylol group.

[0068] Solids of the first base coat composition Preferably, the total solids content of the first base coat composition is in the range of 10 to 65% by weight, more preferably 15 to 60% by weight, even more preferably 20 to 50% by weight, and particularly preferably 25 to 45% by weight, in each case based on the total weight of the first base coat composition. Methods for determining the solids content (non-volatile content) are described in the "Methods" section below.

[0069] Coating layer L2 and the second base coat composition used to form said layer The second coating layer L2 is applied on top of the first coating layer L1. Therefore, the second coating layer L2 is preferably disposed on top of the coating layer L1. The second coating layer L2 is formed from a coating composition containing at least one block copolymer BBCP. This coating composition, also referred to herein as the second basecoat composition, is the composition used in step (2) of the method of the present invention.

[0070] The second base coat composition may be an aqueous, i.e., water-borne, coating composition. Alternatively, the second base coat composition may be a solvent-borne base coat composition. Particularly preferred is a solvent-borne base coat composition. The base coat composition may be a 1K (one-component) composition or a 2K (two-component) composition. Preferably, it is a 1K composition.

[0071] Preferably, the second base coat composition does not contain a pigment. Preferably, the second base coat composition does not contain a filler, and most preferably does not contain both a pigment and a filler. Alternatively, however, the coating composition comprising at least one block copolymer BBCP is a pigmented coating composition.

[0072] Most preferably, the second basecoat composition is a solvent-borne coating composition, which is preferably pigment-free.

[0073] Preferably, the total solids content of the second base coat composition is in the range of 15 to 70% by weight, more preferably 20 to 65% by weight, even more preferably 25 to 60% by weight, and particularly preferably 30 to 55% by weight, in each case based on the total weight of the second base coat composition. Methods for determining the solids content (non-volatile content) are described in the "Methods" section below.

[0074] block copolymer The second base coat composition necessarily comprises at least one block copolymer BBCP. As already outlined above, the block copolymer used in the present invention will also be referred to below and in the present specification as copolymer BBCP.

[0075] Preferably, the at least one copolymer BBCP is present in the coating composition used to prepare the second coating layer L2 in an amount ranging from 10 to 100% by weight, more preferably from 15 to 100% by weight, even more preferably from 20 to 95% by weight, in each case based on the total solids content of the coating composition.

[0076] At least one block copolymer BBCP comprises a main chain and at least two blocks B1 and B2, each different from the other. Block B1 comprises at least one side chain S1 attached to the main chain, and block B2 comprises at least one side chain S2 attached to the main chain, which is different from side chain S1. Each of side chains S1 and S2 is attached to the main chain of the copolymer BBCP used in the present invention, which copolymer is necessarily a block copolymer comprising at least two blocks B1 and B2, where block B1 also comprises said side chain S1, block B2 also comprises said side chain S2, and it is clear that at least a portion of the main chain of the copolymer used in the present invention to which side chain S1 is attached is also part of block B1, and at least a portion of the main chain of the copolymer used in the present invention to which side chain S2 is attached is also part of block B2. It is further clear that the portion of block B1 to which the side chain S1 is attached, but which does not constitute at least one side chain S1, also constitutes part of the main chain of the copolymer, and that the portion of block B2 to which the side chain S2 is attached, but which does not constitute at least one side chain S2, also constitutes 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 bonded to the main chain of the block copolymer BBCP. The main chain (backbone) of the copolymer BBCP preferably, but not necessarily, contains an ethylenically unsaturated carbon-carbon double bond.

[0077] The copolymer BBCP can be preferably obtained by ring-opening metathesis polymerization (ROMP) using cyclic ethylenically unsaturated, preferably cyclic olefinic, monomers. ROMP is a specific olefin metathesis chain-growth polymerization. The driving force behind this reaction is the relaxation of ring strain in cyclic olefins (e.g., norbornene or cyclopentene monomers).

[0078] Preferably, the backbone of the copolymer BBCP contains olefinic carbon-carbon double bonds, more preferably arranged in a regular and / or repeating pattern, and even more preferably arranged so that each structural unit described below 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 this manner, i.e., by ROMP, the formed carbon-carbon double bonds present in the backbone may then optionally be hydrogenated to saturated carbon bonds such as alkylene moieties.

[0079] Those skilled in the art are aware of methods for preparing copolymers BBCP, in particular those prepared via ROMP: such copolymers BBCP are known and are disclosed, for example, in WO 2020 / 160299 A1, WO 2020 / 180427 A1, and BRSveinbjoernsson et al., PNAS 2012, 109(36), pp. 14332-14336. The preparation of copolymers BBCP is also described in these documents and, in the case of cited journal articles, in their supplementary information.

[0080] The block copolymer BBCP is preferably a linear block copolymer. The block copolymer BBCP preferably has a block-like arrangement of copolymer structural units derived at least in part from a suitable ethylenically unsaturated monomer, preferably a cyclic olefin. Preferably, no (meth)acrylic monomers are used in the preparation of the block copolymer BBCP.

[0081] 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 block(s), for example, a triblock copolymer.

[0082] A block copolymer is a copolymer obtained by adding at least two different ethylenically unsaturated monomers, a mixture of two different ethylenically unsaturated monomers, or a mixture of an ethylenically unsaturated monomer and an ethylenically unsaturated monomer at different times during controlled polymerization, where the ethylenically unsaturated monomer or the mixture of ethylenically unsaturated monomers is initially charged at the beginning of the reaction. By the time additional ethylenically unsaturated monomers or the mixture of ethylenically unsaturated monomers are added, or the ethylenically unsaturated monomers are added in multiple batches, the ethylenically unsaturated monomers added at the beginning of the polymerization have already fully reacted or have not yet partially polymerized. As a result of such polymerization, the block copolymer may have at least one transition in its 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 of two structural units per block.

[0083] Preferably, the block copolymer BBCP is of the AB, ABA, BAB, ABC and / or ACB type, in which the A, B and C blocks represent different compositions of structural units, where the A, B and C blocks differ in their respective compositions of structural units and / or the amount of structural units in two adjacent blocks differs from one another by more than 5% by weight in each case. However, most preferred are AB diblock copolymers.

[0084] 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 6000 kDa, more preferably in the range of 500 to 2500 kDa, even more preferably in the range of 550 to 2000 kDa, even more preferably in the range of 600 to 1500 kDa, especially in the range of 650 to 1000 kDa. n )

[0085] Number average molecular weight (M n ) measurement method, mass average molecular weight (M w Methods for measuring the chromaticity and polydispersity index (PDI) are described in the Methods section below.

[0086] As previously described herein, 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.

[0087] Preferably, the side chains are not introduced into the copolymer BBCP after it has already been polymerized in a polymer-analogous reaction. Rather, the side chains are preferably introduced into the appropriate monomers used in the polymerization reaction to prepare the copolymer BBCP. Since these monomers have the aforementioned polymeric moieties, the corresponding monomers represent macromonomers.

[0088] Preferably, cyclic olefins are used to prepare the copolymer BBCP, more preferably norbornene or cyclopentene monomers. Polymer moieties such as M1 and M2 can be introduced into such monomers by using norbornene or cyclopentene monomers having at least one functional group, such as a carboxylic acid group and / or a hydroxyl group.

[0089] Examples of suitable norbornene monomers include: [ka] For example, (B) can be used as an initiating alcohol for the tin-catalyzed polymerization of lactides, such as racemic lactide, to obtain a polylactide macromonomer having an OH-functional end group and a norbornene functional group at the other end. The polylactide unit represents a polyester moiety as an example of the polymer moiety M1. Therefore, this norbornene moiety can be used in ROMP to prepare a copolymer BBCP. The preparation of such a macromonomer 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 prepare a suitable macromonomer suitable for ROMP. For example, a polymer having a terminal OH-group, such as polystyrene, can be prepared. The terminal OH-group of this precursor can then be converted to an ester bond by reaction with (A) to obtain a suitable macromonomer having a polystyrene moiety as the polymer moiety M2. The preparation of such macromonomers is described, for example, in Example 2 of WO 2020 / 180427 A1.

[0090] 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, whereby the polymer moiety M1 is preferably selected from the group consisting of aliphatic polyester moieties and preferably aliphatic polyether moieties, and in particular represents 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 that is free of both hydroxyl and carboxylic acid groups, whereby the polymer moiety M2 is preferably selected from the group consisting of polyether moieties, polysiloxane moieties and polystyrene moieties, and in particular represents a polystyrene moiety.

[0091] Preferably, the first block B1 of the copolymer BBCP comprises at least one structural unit SU1a and optionally at least one structural unit SU1b, where the structural unit SU1a is represented by at least one of the substructures PS1a-1 and PS1a-2, and the optionally present structural unit SU1b is represented by the substructure PS1b, where all structural units present in the first block are preferably randomly arranged in the first block B1 of the copolymer BBCP.

[0092] [ka]

[0093] 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 1 to 1000, preferably 1 to 750, more preferably 2 to 500, and even more preferably 3 to 300; The relative ratio of the parameters x:a is in the range of 1:0 to 1:3, preferably 2:1 to 1:2; M x , J1 and G independently represent CH2 or C=O; Q represents a divalent alkyl, heteroalkyl, cycloalkyl, heterocycloalkyl, aryl, or heteroaryl residue; R x represents a side chain S1 containing a polymer moiety M1, and is 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).

[0094] Preferably, the second block B2 of the copolymer BBCP comprises at least one structural unit SU2a and optionally at least one structural unit SU2b, wherein the structural unit SU2a is represented by at least one of the substructures PS2a-1 and PS2a-2, and the optionally present structural unit SU2b is represented by the substructure PS2b, and all structural units present in the second block are preferably randomly arranged within the second block B2 of the copolymer BBCP.

[0095] [ka]

[0096] 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 the parameters y:b is in the range of 1:0 to 1:3, preferably 2:1 to 1:2; M y , J2 and G independently represent CH2 or C=O; Q represents a divalent alkyl, heteroalkyl, cycloalkyl, heterocycloalkyl, aryl, or heteroaryl residue; R y represents a side chain S2 containing 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 bonded; R2 represents a C1-C6-alkyl residue, preferably a branched C1-C6-alkyl residue).

[0097] Preferably, the parameters a and 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 from 1:0.5 to 1:1, 1:1.5, 1:2, or 1:2.5. Preferably, the ratio of y:b is from 1:0.5 to 1:1, 1:1.5, 1:2, or 1:2.5.

[0098] Preferably, a+x+b+y is in the range of 100 to 500, more preferably in the range of 120 to 480, even more preferably in the range of 140 to 400, even more preferably in the range of 160 to 350, and particularly preferably in the range of 180 to 300.

[0099] 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, for example, 1 to 20 carbon atoms, such as 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 mean an alkyl, as defined above, having at least one heteroatom, preferably selected from nitrogen, sulfur, oxygen, and / or at least one heteroatom-containing group. The term "cycloalkyl" preferably refers to a cyclic alkyl group, e.g., of 3 to 10 carbon atoms, having a single cyclic ring or multiple condensed rings. Cycloalkyl groups include, for example, single-ring structures such as cyclopropyl, cyclobutyl, cyclopentyl, and 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" preferably refers to a saturated or partially saturated monocyclic, bicyclic, or polycyclic ring containing at least one heteroatom, preferably 1 to 3 heteroatoms, selected from nitrogen, sulfur, or oxygen in at least one ring. Each ring preferably has 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-oxazepane, and 1,4-oxathiapane. This group can be a terminal or bridging group. The term "aryl" preferably refers to an aromatic hydrocarbon group. An aryl group can have 6 to 30 carbon atoms, e.g., 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, where at least one ring is aromatic (e.g., naphthyl, dihydrophenanthrenyl, fluorenyl, or anthryl). Typical aryl groups include, but are not limited to, radicals derived from benzene, naphthalene, anthracene, and biphenyl. Aryl can be unsubstituted or optionally substituted. The term "heteroaryl" preferably refers to a monocyclic, bicyclic, or tricyclic ring system containing one, two, or three aromatic rings and at least one nitrogen, oxygen, or sulfur atom and / or heteroatom-containing group in the aromatic ring. Heteroaryl can be unsubstituted or substituted, for example, with one or more, especially 1 to 3, 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-quinolidinyl, acridinyl, benzo[b]thienyl, benzothiazolyl, b-carbolinyl, carbazolyl, chromenyl, cinnolinyl, dibenzo[b,d]furanyl, furazanyl, furyl, imidazolyl, imidizolyl, indazolyl, indolizinyl, indolyl, isobenzofuranyl, isoindolyl, isoquinolyl, isothiazolyl, isoxazolyl, naphthyridinyl, oxazolyl, and perimidinyl. "Heteroaryl" includes, but is not limited to, diphenyl, phenanthridinyl, phenanthrolinyl, phenarsazinyl, phenazinyl, phenothiazinyl, phenoxathinyl, phenoxazinyl, phthalazinyl, pteridinyl, purinyl, pyranyl, pyrazinyl, pyrazolyl, pyridazinyl, pyridyl, pyrimidinyl, pyrrolyl, quinazolinyl, quinolyl, quinoxalinyl, thiadiazolyl, thianthrenyl, thiazolyl, thienyl, triazolyl, tetrazolyl, and xanthenyl. Preferably, "heteroaryl" refers to a monocyclic aromatic ring containing 5 or 6 ring atoms containing carbon and 1, 2, 3, or 4 heteroatoms independently selected from non-peroxide oxygen, sulfur, and N(Z), where Z is absent or is H, O, alkyl, aryl, or (C1-C6)alkylaryl. Heteroaryl may also refer to an ortho-fused bicyclic heterocycle of about 8 to 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 to 20, or 1 to 10, or 1, 2, 3, 4, or 5, or 1, 2, or 3, or 1 or 2) hydrogens on the group designated using "substituted" (or "substituent") are replaced with one or more selected from the designated group(s) or suitable groups known to those skilled in the art, provided that the normal valence of the designated atom is not exceeded and that the substitution results in a stable compound.Suitable illustrative groups include, for example, alkyl, alkenyl, alkynyl, alkoxy, halo, haloalkyl, hydroxy, hydroxyalkyl, aryl, heteroaryl, heterocyclyl, cycloalkyl, alkanoyl, alkoxycarbonyl, amino, alkylamino, dialkylaminotrifluoromethylthio, difluoromethyl, acylamino, nitro, trifluoromethyl, trifluoromethoxy, carboxy, carboxyalkyl, keto, thioxo, alkylthio, alkylsulfomyl, alkylsulfonyl, and cyano. Further non-limiting examples of substituents that can be bonded to a substituted carbon (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', SOR', SOR(R'), 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 Examples include 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')S02R', N(R')S02N(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.

[0100] The main chain of the copolymer BBCP preferably contains an ethylenically unsaturated carbon-carbon double bond, and the structural units present in each block are preferably covalently bonded such that each unit is connected to another unit via a carbon-carbon double bond. The copolymer BBCP, when linear as preferred, further preferably contains two end groups. Each of these end groups is covalently bonded to one structural unit. The end groups (i.e., initiator end or end) of the copolymer are preferably low molecular weight (e.g., 500 Da or less) moieties, such as H, OH, COOH, CHOH, CN, NH, or alkyl (e.g., butyl or 2-cyanoprop-2-yl moieties at the initiator end and end), hydrocarbons such as alkenes or alkynes, or moieties resulting from elimination reactions at the first and / or last repeating units in the copolymer.

[0101] Preferably, the block copolymer BBCP is a brush block copolymer. Brush block copolymers contain a main chain (backbone) with linear, unbranched side chains. A brush is characterized by a high density of grafted chains, allowing the side chains to extend strongly in a limited space. 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 the parameters x: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 parameters y:b is in the range of 2:1 to 1:2, preferably in the range of 1.5:1 to 1:1.5, and the remaining residues and variables have one or more of the meanings defined herein.

[0102] Preferably, the coating composition comprising at least one block copolymer BBCP used for preparing the second coating layer L2 further comprises at least one linear homopolymer, more preferably selected from polyester, poly(meth)acrylate, polyether, polysiloxane and polystyrene homopolymers, even more preferably selected from polystyrene, polyether and polyester homopolymers and mixtures thereof, even more preferably selected from polystyrene and aliphatic polyesters such as polylactide homopolymers, and mixtures thereof, wherein the at least one homopolymer preferably has a number average molecular weight (M n ) that is at least 100 times, preferably at least 150 times, more preferably at least 175 times lower than the number average molecular weight (M n ), and preferably the relative weight ratio of the solids of the BBCP copolymer to the solids of the at least one homopolymer in the coating composition is in the range of 99:1 to 5:95, more preferably in the range of 95:5 to 10:90, even more preferably in the range of 90:10 to 15:85, even more preferably in the range of 85:15 to 20:80, even more preferably in the range of 75:25 to 25:75, and particularly preferably in the range of 60:40 to 30:70. n ), mass average molecular weight (M w The methods for measuring the polydispersity index (PDI) and the molecular weight distribution are described in the "Methods" section below.

[0103] Methods for preparing such homopolymers are disclosed, for example, in WO 2020 / 160299 A1 (pages 25 / 26, Example 1) and WO 2020 / 180427 A1 (pages 25 / 26, Example 1).

[0104] Preferably, the at least one homopolymer is present in the second base coat composition in an amount ranging from 0 to 90% by weight, preferably from 20 to 80% by weight, more preferably from 40 to 60% by weight, and in particular from 30 to 70% by weight, in each case based on the total solids content of the second base coat composition.

[0105] Preferably, the relative weight ratio of the solids of the BBCP copolymer to the solids of the at least one homopolymer in the second base coat composition is in the range of 99:1 to 5:95, preferably in the range of 95:5 to 10:90, more preferably in the range of 90:10 to 15:85, even more preferably in the range of 85:15 to 20:80, even more preferably in the range of 75:25 to 25:75, and particularly preferably in the range of 60:40 to 30:70.

[0106] 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, if such homopolymers are present, besides the at least one homopolymer as defined above, at least one further resin, more preferably at least one polymeric resin, wherein the relative weight ratio of BBCP copolymer solids to the solids of the at least one further resin within the coating composition is 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, even more preferably 20:80 to 90:10, even more preferably 25:75 to 85:15, particularly preferably 30:70 to 80:20 and most preferably 40:60 to 80:20.

[0107] Preferably, the coating composition comprising at least one block copolymer BBCP used to prepare the second coating layer L2 comprises, in addition to the copolymer BBCP and, if such homopolymer is present, in addition to the at least one homopolymer as defined above, at least one further resin, the relative weight ratio of the sum of the BBCP copolymer solids and homopolymer solids (if present) to the solids of the at least one further resin in the top coat composition being preferably in the range of 40:60 to 100:0, more preferably 45:55 to 100:0, even more preferably 50:50 to 95:5, even more preferably 55:45 to 90:10, even more preferably 60:40 to 85:15.

[0108] binder In addition to the copolymer BBCP and the at least one homopolymer present, at least one additional resin, preferably at least one polymeric resin, optionally present in the second base coat composition preferably functions as at least one binder (b1). The same binders containing a crosslinker (i.e., crosslinking agent) described herein above in connection with component (a1) and below in connection with component (c1) 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 the homopolymer described above.

[0109] Coating layer L3 and the coating composition used to form said layer The third coating layer L3 is applied on top of the second coating layer L2, so that the third coating layer L3 is preferably located on top of the coating layer L2 and in direct contact with the layer L2.

[0110] Preferably, the third coating layer L3 is a clear coat layer formed from a coating composition that is a clear coat composition, preferably a solvent-borne clear coat composition, where the third coating layer L3 is preferably the outermost coating layer of a multi-layer coating system. This coating composition, also referred to herein as a top coat composition, is the composition used in step (3) of the method of the present invention.

[0111] The topcoat composition may be an aqueous, i.e., water-borne coating composition. Alternatively, it may be a solvent-borne basecoat composition. In particular, it is actually a solvent-borne clearcoat composition. The topcoat composition may be a 1K- (one-component) or 2K- (two-component) composition.

[0112] Preferably, the total solids content of the top coat composition is in the range of 10 to 65% by weight, more preferably 15 to 60% by weight, even more preferably 20 to 50% by weight, and particularly preferably 25 to 45% by weight, in each case based on the total weight of the top coat composition.

[0113] The top coat composition preferably comprises at least one binder, more preferably at least one polymer (c1) as the binder. The same binders with crosslinkers described above in connection with components (a1) and (b1) can also be used as component (c1).

[0114] Preferably, the top coat composition comprises at least one polymer (c1) having on average two or more OH- and / or amino and / or carbamate groups, more preferably two or more 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 2 , measured by gel permeation chromatography (GPC) against polystyrene standards. w However, it is preferably 800 to 100,000 g / mol, more particularly 1,000 to 75,000 g / mol.

[0115] If the top coat 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 a crosslinking agent.If the top coat 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 a crosslinking agent.

[0116] Component (c1) suitable for use as a crosslinking agent is an organic component having an average of two or more NCO groups. At least one organic component used as a crosslinking agent preferably has an alicyclic structure and / or a parent structure derived from an alicyclic polyisocyanate by trimerization, dimerization, urethane formation, biuret formation, uredione formation, and / or allophanate formation. Alternatively or additionally, at least one organic component used as a crosslinking agent preferably has an acyclic aliphatic structure and / or a parent structure derived from an acyclic aliphatic polyisocyanate by trimerization, dimerization, urethane formation, biuret formation, uredione formation, and / or allophanate formation. The acyclic aliphatic polyisocyanate (optionally serving as a parent structure) is preferably a substituted or unsubstituted aliphatic polyisocyanate known per se. Examples include tetramethylene 1,4-diisocyanate, hexamethylene 1,6-diisocyanate, 2,2,4-trimethylhexane 1,6-diisocyanate, ethylene diisocyanate, dodecane 1,12-diisocyanate, and mixtures of the aforementioned polyisocyanates. The cycloaliphatic polyisocyanates (optionally serving as parent structures) are preferably substituted or unsubstituted cycloaliphatic polyisocyanates known per se. Examples of preferred polyisocyanates include isophorone diisocyanate, cyclobutane 1,3-diisocyanate, cyclohexane 1,3-diisocyanate, cyclohexane 1,4-diisocyanate, methylcyclohexyl diisocyanate, hexahydrotoluene 2,4-diisocyanate, hexahydrotoluene 2,6-diisocyanate, hexahydrophenylene 1,3-diisocyanate, hexahydrophenylene 1,4-diisocyanate, perhydrodiphenylmethane 2,4'-diisocyanate, 4,4'-methylenedicyclohexyl diisocyanate (e.g., Desmodur® W from Bayer AG), and mixtures of the aforementioned polyisocyanates. The organic components having an average of two or more NCO groups can also be partially silanized.Such silanized crosslinkers are disclosed, for example, in WO 2010 / 063332 A1, WO 2010 / 139375 A1 and WO 2009 / 077181 A1.

[0117] Component (c1) suitable for use as a crosslinker, particularly when the topcoat composition is formulated as a 1K coating composition, is a melamine formaldehyde resin. The same melamine formaldehyde resins as previously described herein in connection with component (a1) can be used.

[0118] Preferably, the topcoat composition 3) does not contain a copolymer (BBCP) such as is present in the second basecoat composition.

[0119] The top coat composition may not be pigmented. However, even if the top coat composition is formulated as a clear coat composition, it may alternatively contain color pigments and / or effect pigments, preferably color pigments, in an amount that does not interfere with the desired transparency of the cured clear coat. For example, the clear coat composition may contain up to 7.5% by weight, preferably up to 5.0% by weight, more preferably up to 2.5% by weight, and even more preferably up to 1.5% by weight of at least one color pigment, in each case based on the total solids content of the clear coat composition. The same applies to any fillers optionally present in the clear coat composition. However, preferably, the clear coat composition does not contain pigments and / or fillers.

[0120] A multi-layer coating system of the present invention comprising layers L1, L2 and L3 overlying a substrate S precoated with a primer P is illustrated in FIG.

[0121] Methods of the Invention The method of the present invention is a method for preparing the multi-layer coating system of the present invention on an optionally pre-coated substrate, comprising at least steps (1), (2), (3) and (4).

[0122] The method of the present invention is suitable for both automotive OEM and refinish applications, and is particularly suitable for automotive OEM applications.

[0123] Preferably, each of steps (1) to (3) is carried out by spray coating.

[0124] At this stage, at least the second and third coating films, and optionally also the first coating film, are preferably uncured coating films after performing each step(s). Therefore, the coating composition applied at least in step (3) is preferably applied wet-on-wet onto the second coating film obtained after performing step (2). When only the obtained second and third coating films are cured simultaneously, the first coating film applied in step (1) is cured before performing step (2). However, the coating composition applied in step (2) is also preferably applied wet-on-wet onto the first coating film obtained after performing step (1). In this case, when step (2) is performed, the first coating film is still an uncured coating film. When the obtained first, second, and third coating films are cured simultaneously in step (4), the method of the present invention is a wet-on-wet-on-wet method.

[0125] Process (1) According to step (1), a first basecoat composition comprising at least one platelet-shaped pigment is applied 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. The basecoat composition used in step (1) of the method of the present invention is also referred to as the "first basecoat composition."

[0126] Optional step (1a) Preferably, the method of the present invention further comprises step (1a) carried out after step (1) and before step (2). In step (1a), the first coating film obtained after step (1) is flashed off preferably for 1 to 20 minutes, more preferably for 2 to 15 minutes, and particularly preferably for 5 to 10 minutes before applying the second base coat composition in step (2). Preferably, step (1a) is carried out at a temperature not exceeding 80°C, more preferably at a temperature in the range of 30°C to 60°C.

[0127] The term "flash-off" in the sense of the present invention preferably means at least partial "drying", in which at least part of the solvent (water and / or organic solvent(s)) is evaporated from the coating film before the next coating composition is applied and / or curing is carried out. Preferably, no curing, or at least no complete curing, is carried out by flash-off.

[0128] Optional step (1b) Preferably, the method of the present invention further comprises step (1b) carried out after step (1) or step (1a) and before step (2). In step (1b), the first coating film obtained after step (1) or step (1a) is cured before applying the second base coat composition in step (2). The same curing conditions can be used / applied as those outlined in detail in connection with step (4) below. Preferably, steps (1a) and / or (1b) are carried out. More preferably, at least step (1b) is carried out such that the second base coat composition applied in step (2) is applied onto the cured first coating film.

[0129] Process (2) According to step (2), a second base coat composition comprising at least one block copolymer BBCP and different from the base coat composition applied in step (1) is applied to the first coating film present on the substrate obtained after step (1) to form a second coating film, which second coating film is preferably adjacent to the first coating film.

[0130] Step (2) can be carried out before curing the first coating film obtained after step (1). Alternatively, step (2) is preferably carried out after curing the first coating film obtained after step (1), i.e., after carrying out at least optional step (1b).

[0131] Optional step (2a) Preferably, the method of the present invention further comprises step (2a) carried out after step (2) and before step (3). In step (2a), the second coating film obtained after step (2) is flashed off preferably for 1 to 20 minutes, more preferably for 2 to 15 minutes, and particularly preferably for 5 to 10 minutes before applying the top coat composition in step (3). 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.

[0132] Process (3) According to step (3), a coating composition different from the compositions applied in steps (1) and (2) is applied to the second coating film present on the substrate obtained after step (2), preferably forming a third coating film adjacent to the second coating film, said coating composition being a topcoat composition, preferably a clearcoat composition.

[0133] Preferably, the third coating film obtained after step (3) is the outermost film of the formed multi-layer coating system.

[0134] Optional step (3a) Preferably, the method of the present invention further comprises step (3a) carried out after step (3) and before step (4). In step (3a), the third coating film obtained after step (3) is flashed off preferably for 1 to 20 minutes, more preferably for 2 to 15 minutes, and particularly preferably for 5 to 10 minutes before carrying out the curing step (4). Preferably, step (3a) is carried out at a temperature not exceeding 40°C, more preferably at a temperature in the range of 18 to 30°C.

[0135] Process (4) According to step (4), at least the second and third coating films applied in steps (2) and (3), and optionally the first coating film applied in step (1) (if said first coating film was not cured before performing step (2)), are cured simultaneously, i.e., simultaneously, to obtain a multi-layer coating system comprising at least first, second, and third coating layers L1, L2, and L3, each of which represents a coating layer.

[0136] Preferably, step (4) 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 5 to 45 minutes, preferably 20 to 45 minutes, in particular 25 to 35 minutes. Preferably, however, the minimum curing temperature applied in step (4) is at least 80°C. In this case, curing in step (4) is preferably carried out at a temperature in the range of 80 to <180°C or 80 to <160°C.

[0137] Preferably, the curing according to step (4) is selected from chemical curing, such as chemical crosslinking, radiation curing, and / or physical drying (non-chemical curing), in each case at room temperature or at an elevated temperature, more preferably selected from chemical curing, such as chemical crosslinking, and / or physical drying (non-chemical curing), in each case at room temperature or at an elevated temperature, in each case preferably the minimum curing temperature applied in step (4) is at least 80°C.

[0138] Coated Substrates of the Invention A further subject of the present invention is a coated substrate obtainable by the method of the present invention.

[0139] All preferred embodiments described herein above with respect to the inventive method and the inventive multi-layer coating system are also preferred embodiments with respect to the inventive coated substrates described above.

[0140] method 1. Determination of Nonvolatile Fraction The amount of solids (non-volatile matter, percentage of solids) including the total solids is determined according to DIN EN ISO 3251:2019-09 at 110°C for 60 minutes.

[0141] 2.M n , M W and PDI measurement Polymer molecular weight (number average molecular weight (M n ) and mass average molecular weight (M W The molecular weight distribution (PDI; polydispersity index) and molecular weight distribution (PDI) were measured using gel permeation chromatography (GPC) combined with a differential refractive index (dRI) and two light scattering (LS) detectors. The use of the LS detector enabled the analysis of the absolute molecular weight of the polymer samples. The solvent for all samples was tetrahydrofuran (THF), and the elution rate was 1.0 mL / min. Polymer samples were completely dissolved in HPLC-grade THF at concentrations between 2.5 and 7.5 mg / mL, passed through a 0.5 μm syringe filter, and injected using an autosampler. The porous column stationary phase consisted of two Malvern T600 single-pore columns with an exclusion limit of 20,000,000 Da of poly(styrene). The molecular weight and PDI were determined using OMNISEC software.

[0142] 3.L * , a * , b * , C * , and determination of h value The color data of the three-layer coating was determined using a Byk Mac i instrument (Byk Gardner GmbH, Germany). D65 illumination (10° observation angle) was used. The multi-angle (-15°, +15°, +25°, +45°, +75°, +110° observation angles) measurement geometry is shown in Figure 2. The 110° angle is also referred to as the "flop angle." Using the above-mentioned equipment, two-layer coating and three-layer coating L * , a * , and b * The value was measured. * is calculated using the following formula: * =(a 2 +b 2 ) 0.5 , and h = arctan(b / a).

[0143] The CIELAB formula is a * Axis, extending from blue to yellow b * axis, and the lightness axis L perpendicular to the other two * defines a color space characterized by b * A negative value of b means a bluish color, * Positive values ​​of L represent a more yellowish color. * (i.e., lightness) values ​​represent brighter colors, and L * The lower the value, the darker the color.

[0144] 4. Determining the dry thickness of the coating layer The dry thickness of the coating layer of the present invention was measured using an Elcometer, for example a Fischer Dualscope FMP20C. [Example]

[0145] The following examples further illustrate the present invention but are not to be construed as limiting its scope. "Pbw" means parts by weight. Unless otherwise defined, "parts" means "parts by weight" and, unless otherwise indicated, all "%" values ​​are "% by weight."

[0146] Preparation of the copolymers 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 Equimolar amounts of d,x-DME (dimethyl-5-norbornene-2,3-dicarboxylate, d = inside, x = outside) were added to dichloromethane. PLA-MM was prepared by tin-catalyzed ring-opening polymerization of lactide using norbornene alcohol initiator to obtain OH- and norbornene-functional polylactic acid 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. Next, a bisbipyridine ruthenium catalyst was rapidly added to the mixture of PLA-MM and d,x-DME to initiate copolymerization, resulting in PLA. 100 -r-DME 100 The target was 1. The "r" indicates that the two monomer units, PLA and DME, were randomly arranged. The mixture was stirred at room temperature for 45 minutes (first block mixture). In a separate container under an inert atmosphere, norbornene-functionalized polystyrene macromonomer (PS-MM; M of 3.83 kDa) was added. nA solution of d,x-diisopropyl-5-norbornene-2,3-dicarboxylate (d = in, x = out) and d,x-DIPE (diisopropyl-5-norbornene-2,3-dicarboxylate, d = in, x = out) was prepared in dichloromethane (second block mixture). PS-MM was previously prepared in two steps by the general method described in Example 2 of WO 2020 / 180427 A1: the OH-functional polymeric precursor of PS-MM was prepared by polymerization of styrene in toluene with sec-butyllithium as the initiator. After chain termination by the addition of propylene oxide and then methanol, quenching was performed. Next, the terminal OH-groups of the resulting precursor were converted to ester bonds by reaction with norbornene carboxylic acid to obtain PS-MM. The solution of PS-MM and d,x-DIPE was rapidly added to the first block reaction mixture. The two monomer units PS and DIPE are randomly arranged within the second block of the formed copolymer. The resulting mixture was stirred at room temperature for an additional 4 hours and then quenched by the addition of ethyl vinyl ether. The quenched catalyst was then captured using a functionalized silica gel absorbent and stirred for approximately 4 hours. The mixture was filtered, and the solution was concentrated under reduced pressure. After removing the solvent, a solid copolymer was obtained. This was dried in a vacuum oven at 75°C for 4 hours to remove residual solvent. The resulting product (BBCP1) was used in this form.

[0147] BBCP1 has a number-average molecular weight (M n ), mass-average molecular weight (M W ), thus the polydispersity index (PDI) was 1.10.

[0148] Preparation of the Coating Composition To illustrate the unique color properties of brush block copolymers and provide non-limiting examples of the color space possibilities achievable with brush block copolymers, three different colors were produced by overlaying a second basecoat layer containing brush block copolymer on three different first basecoat layers, designated A, B, and C, made with conventional and effect pigments. By combining metallic or pearlescent effect coating layers together with the brush block copolymer, unique and aesthetically pleasing colors are obtained.

[0149] First base coat composition according to the present invention The first basecoat compositions A, B and C used in the present invention (layers of the process of the present invention) are waterborne one-pack compositions, each comprising the following combination of platelet-like interference pigment and carbon black pigment paste: titanium dioxide-coated silica effect pigment in flake form (Colorstream T20-04 WNT Lapis Sunlight); or Aluminum pigment coated with flake-shaped organic blue pigment (Friend Color D462 BL), or ●Fluorine-free mica effect pigment coated with flake-shaped titanium dioxide (Pyrisma T81-23 SW Liquid Blue).

[0150] The specific composition is shown in Table 2.

[0151] Second base coat composition according to the present invention To produce the colors of the present invention, first basecoat compositions A, B, and C were each coated with a second basecoat composition D containing a brush block copolymer.

[0152] This second basecoat composition was obtained by preparing a solution of 1.50 g of BBCP1, 0.75 g of polystyrene homopolymer (PS-HP), 0.75 g of polylactide homopolymer (PLA-HP), and 7 g of n-butyl acetate, with a relative weight ratio of BBCP1 solids to the combined PS-HP and PLA-HP solids in BC3 of 50:50.

[0153] Third Coating Composition (Clear Coat) According to the Invention As the clear coat, a commercially available high-solids Uregloss (registered trademark) clear coat (R10CG392D; manufactured by BASF Corp. USA) was used.

[0154] Comparative second basecoat composition To illustrate the unique color space achieved by the above stacking, a series of separate control experiments were conducted in which inventive first basecoat compositions A, B, and C were coated with a non-inventive second basecoat composition E (see Table 4) containing conventional pigments in an attempt to match the color space as closely as possible.

[0155] In this scheme, (A+D), (B+D), and (C+D), respectively, with the addition of a clear coat of the present invention, were compared to comparative colors produced by (A+E), (B+E), and (C+E), respectively, with the addition of a clear coat of the present invention.

[0156] Further comparative examples Additionally, another set of control experiments was conducted whereby multiple combinations of conventional and effect pigments were used in an attempt to match the color space of the present invention. Comparative compositions F, G, and H (see Table 3) are aqueous one-pack compositions, each containing a platelet-like effect pigment in combination with a non-platelet-like organic pigment and an inorganic pigment, the latter incorporated into the composition in the form of a pigment paste as described in Table 1.

[0157] Coating compositions F, G, and H represent an attempt to match the color characteristics of three inventive multi-layer coating compositions resulting from using inventive first basecoat compositions A, B, and C in laminate with inventive second basecoat composition D.

[0158] Coating compositions F, G, and H are non-hiding compositions applied over a black primer, attempting to match the color of (A+D), (B+D), and (C+D), respectively. In this scheme, (A+D), (B+D), and (C+D) were compared with the comparative colors produced by (black primer + F), (black primer + G), and (black primer + H), respectively. The composition of the black primer is not particularly limited, and multiple grades can be used. Note that the lightness value L of the black primer used in the examples is * was 8.

[0159] Additionally, in all comparative examples, the clear coat of the present invention was also applied as a top coat.

[0160] The components of compositions A, B, C, E, F, G, and H are shown in Tables 1 to 4.

[0161] Applications of multi-layer coated (2-layer and 3-layer coated) films The first base coat compositions A, B, C of the present invention and the comparative base coat compositions F, G, and H were applied onto the baked primer layer by air pressure manual application to form base coat layers having a dry layer thickness of about 20 μm (base coat layer L1, i.e., L1(A), L1(B), and L1(C) from base coat compositions A, B, and C, respectively), a coating layer thickness of about 18 μm (coating layers F and G from base coat compositions F and G, respectively), and a coating layer thickness of about 14 μm (coating layer H from coating composition H).

[0162] In one set of examples, a second base coat composition D was applied wet-on-wet by pneumatic manual application over base coat layers L1(A), L1(B), and L1(C), respectively, after a 1-3 minute flash, to form layer L2(D). A non-inventive second base coat composition E was applied by pneumatic manual application after a 1-3 minute flash to form second base coat layer E. The inventive second base coat layer L2(D) had a dry thickness of about 12 μm, and the non-inventive second base coat layer E had a dry thickness of 5 μm.

[0163] In another set of examples, the non-inventive first basecoat layers F, G, and H did not have a second basecoat layer thereon.

[0164] After a 3-5 minute heat (63°C) flash-off, a one-component clearcoat composition was manually applied by air pressure to a dry layer thickness of approximately 40-55 μm.

[0165] The thus coated panels were flashed off for 5-10 minutes and then cured at 130°C for 25 minutes.

[0166] [Table 1] TIFF2025535259000006.tif98170

[0167] [Table 2]

[0168] [Table 3] TIFF2025535259000009.tif25275

[0169] [Table 4]

[0170] result Three-layer coating ([L1(A)]-[L2(D) or E]-[Clear coat]) and two-layer coating ([F]-[Clear coat]) Tables 5-1 and 5-2 compare three multi-layer coatings. The first is an inventive multi-layer coating in which a first basecoat composition A was used to form a first basecoat layer L1(A), followed by a second basecoat layer L2(D) of an inventive basecoat composition D containing a brush block copolymer, followed by a clearcoat composition to form layer L3. The second, non-inventive multi-layer coating in which a first basecoat layer L1(A) was used to form a first basecoat composition A, followed by a second basecoat layer L2(D) of a non-inventive basecoat composition E pigmented with a non-platelet-shaped organic pigment paste, followed by a clearcoat composition to form a topcoat layer. The third multi-layer coating in which only one basecoat composition F was used to form a basecoat layer, followed by a clearcoat composition to form a topcoat layer. The data in Tables 5-1 and 5-2 demonstrate the innovative color space of the inventive multi-layer coatings compared to non-inventive compositions.

[0171] [Table 5]

[0172] In the near off-specular region (angles from -15° to +15°), there is a significant difference in color position of the multilayer coating of the present invention that cannot be achieved with conventional traditional pigments, regardless of whether it is overlaid with a pigmented basecoat composition or composition F.

[0173] [Table 6]

[0174] Three-layer coating ([L1(B)]-[L2(D) or E]-[Clear coat]) and two-layer coating ([G]-[Clear coat]) Tables 6-1 and 6-2 compare three multi-layer coatings. The first is an inventive multi-layer coating in which a first basecoat layer L1 (B) was formed using a first basecoat composition B, followed by a second basecoat layer L2 (D) using a second basecoat composition D of the present invention containing a brush block copolymer, followed by a clearcoat composition to form layer L3. The second, non-inventive multi-layer coating in which a first basecoat layer L1 (B) was formed using a first basecoat composition B, followed by a second basecoat layer using a non-inventive second basecoat composition E pigmented with a non-platelet-shaped organic pigment paste, followed by a topcoat layer using a clearcoat composition. The third multi-layer coating in which only one basecoat composition G was used to form one basecoat layer, followed by a topcoat layer using a clearcoat composition. The data in Tables 6-1 and 6-2 demonstrate the innovative color space of the inventive multi-layer coatings compared to non-inventive compositions.

[0175] [Table 7]

[0176] In the near off-specular region (angles from -15° to +15°), there is a significant difference in color position of the multilayer coating of the present invention that cannot be achieved with conventional traditional pigments, regardless of whether it is overlaid with a pigmented basecoat composition or composition G.

[0177] [Table 8]

[0178] Three-layer coating ([L1(C)]-[L2(D) or E]-[Clear Coat]) and two-layer coating ([H]-[Clear Coat]) Tables 7-1 and 7-2 compare three multilayer coatings. The first is an inventive multilayer coating in which a first basecoat layer L1 (C) was formed using a first basecoat composition C, followed by a second basecoat layer L2 (D) using a second basecoat composition D of the present invention containing a brush block copolymer, followed by a clearcoat composition to form layer L3. The second, non-inventive multilayer coating in which a first basecoat layer L1 (C) was formed using a first basecoat composition B, followed by a second basecoat layer using a non-inventive second basecoat composition E pigmented with a non-platelet-shaped organic pigment paste, followed by a topcoat layer using a clearcoat composition. The third multilayer coating in which only one basecoat composition H was used to form one basecoat layer, followed by a topcoat layer using a clearcoat composition. The data in Tables 7-1 and 7-2 demonstrate the innovative color space of the inventive multilayer coatings compared to non-inventive compositions.

[0179] [Table 9]

[0180] In the near off-specular region (angles from -15° to +15°), there is a significant difference in color position of the multilayer coating of the present invention that cannot be achieved with conventional traditional pigments, regardless of whether it is overlaid with a pigmented basecoat composition or composition H.

[0181] [Table 10]

Claims

1. At least three coating layers L1, L2 and L3, which are present on the optionally precoated substrate and which are different from one another, namely a first coating layer L1 comprising at least one platelet-shaped pigment applied over at least a portion of the optionally precoated substrate; a second coating layer L2 applied over the first coating layer L1; and A third coating layer L3 applied on the second coating layer L2 1. A multi-layer coating system comprising: the second coating 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; a multilayer coating system, wherein the block B1 comprises at least one side chain S1 attached to the main chain, the block B2 comprises at least one side chain S2 attached to the main chain and different from the side chain S1, each side chain S1 comprising at least one polymer moiety M1 selected from the group consisting of polyester, polyether and poly(meth)acrylate moieties, and each side chain S2 comprising 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. 10. The multi-layer coating system of claim 1, wherein said at least one platelet-shaped pigment is selected from the group consisting of metallic effect pigments and special effect pigments.

3. 4. The multi-layer coating system of claim 3, wherein said metallic effect pigments are selected from the group consisting of coated or uncoated metals and alloys, and said special effect pigments are selected from the group consisting of pearlescent pigments and interference pigments.

4. said metallic effect pigments are surface-modified or not and are selected from the group consisting of aluminum platelets, zinc-copper platelets, copper platelets, nickel platelets or steel platelets; The special effect pigment Rutile, anatase, ZrO ２ , SnO ２ , SiO ２ , FeOOH, Fe ２ O ３ , Cr ２ O ３ , TiO ２－ｘ , TiO ｘ N ｙ , KFe[Fe(CN) ６ ], and a platelet selected from the group consisting of mica, silica, alumina, glass, and borosilicate coated with one or more of a colorant coating; and Substrate-free pearlescent pigments, such as platelets selected from the group consisting of natural pearl essence, basic lead carbonate, bismuth oxychloride, finely divided iron oxide, and titanium dioxide flakes.

4. The multi-layer coating system of claim 2 or 3, selected from the group consisting of:

5. The platelet-shaped pigment has a number average platelet thickness h in the range of 30 nm to 1 μm. ５０ , average platelet diameter D in the range of 5 μm to 40 μm ５０ and an average aspect ratio D ranging from about 5:1 to about 1300:1 ５０ / h ５０ and D ５０ is the volume-based average particle size determined by laser diffraction spectroscopy, and h ５０ 3. The multi-layer coating system of claim 1, wherein: is the average grain thickness determined by electron microscopy.

6. 3. The multi-layer coating system according to claim 1 or 2, further comprising a non-platelet shaped visible light absorbing pigment, preferably an organic or inorganic black pigment.

7. 3. The multilayer coating system according to claim 1, wherein the at least one platelet-shaped pigment contained in the first coating layer (L1) is capable of reflecting at least wavelengths that are not reflected by the second coating layer (L2).

8. 3. The multi-layer coating system according to claim 1 or 2, wherein the third coating layer L3 is formed from a coating composition that is a clear coat composition, preferably a solvent-borne clear coat composition, and the third coating layer L3 is preferably the outermost coating layer of the multi-layer coating system.

9. 3. The multi-layer coating system of claim 1, wherein at least the first, second and third coating layers L1, L2 and L3 are disposed adjacent to one another, and the coating layers L2 and L3 are at least partially transparent to visible light.

10. 3. The multilayer coating system according to claim 1, wherein at least the applied coating composition comprising at least one block copolymer used to prepare the second coating layer (L2) and the applied coating composition used to prepare the third coating layer (L3) are cured simultaneously to obtain the second and third coating layers (L2, L3) of the multilayer coating system, wherein the curing is preferably selected from chemical curing, e.g., chemical crosslinking, radiation curing, and / or physical drying (non-chemical curing), in each case at room temperature or at an elevated temperature, more preferably selected from chemical curing, e.g., chemical crosslinking, and / or physical drying (non-chemical curing), in each case at room temperature or at an elevated temperature, and wherein the minimum curing temperature applied for curing is preferably 80°C in each case.

11. 3. A multilayer coating system according to claim 1 or 2, wherein the backbone of said copolymer comprises ethylenically unsaturated carbon-carbon double bonds, said copolymer being obtainable by ring-opening metathesis polymerization (ROMP) using cyclic ethylenically unsaturated monomers, preferably cyclic olefinic monomers.

12. 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 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 3. A multilayer coating system according to claim 1 or 2, wherein each of the side chains S2 of the second block B2 of the copolymer comprises at least one polymer moiety M2 that is free of both hydroxyl and carboxylic acid groups, the polymer moiety M2 being preferably selected from the group consisting of polyether moieties, polysiloxane moieties and polystyrene moieties, in particular representing a polystyrene moiety.

13. The at least one copolymer has a number average molecular weight (M) in the range of 450 to 6000 kDa, more preferably in the range of 500 to 2500 kDa, even more preferably in the range of 550 to 2000 kDa, even more preferably in the range of 600 to 1500 kDa, especially in the range of 650 to 1000 kDa. ｎ 3. The multi-layer coating system of claim 1, wherein the coating comprises:

14. 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 substructures PS1a-1 and PS1a-2, and the optionally present structural unit SU1b being represented by the substructure PS1b, all structural units present being preferably randomly arranged within the first block B1 of the copolymer, 【Chemical Formula 1】 wherein, independently of one another, the parameter x is in the range of 1 to 1000, preferably 1 to 750, more preferably 2 to 500, even more preferably 3 to 300; the parameter a is in the range of 1 to 1000, preferably 1 to 750, more preferably 2 to 500, even more preferably 3 to 300; the relative ratio of the parameters x:a is in the range of 1:0 to 1:3, preferably 2:1 to 1:2; M ｘ , J １ and G are each independently CH ２ or C═O; Q represents a divalent alkyl, heteroalkyl, cycloalkyl, heterocycloalkyl, aryl, or heteroaryl residue; R ｘ represents a side chain S1 comprising a polymer moiety M1, preferably C ２ ~C ６ -Alkylene-O-[C(=O)-C ２ ~C ６ -alkylene-O] ｎ -H, where the parameter n ranges from 1 to 500, preferably from 1 to 300; R １ is C １ ~C ６ - alkyl residue, preferably unbranched C １ ~C ６ -representing 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 substructures PS2a-1 and PS2a-2, and the optionally present structural unit SU2b being represented by the substructure PS2b, all structural units present being preferably randomly arranged within the second block B2 of the copolymer, 【Chemistry 2】 wherein, independently of one another, the parameter y is in the range of 1 to 1000, preferably 1 to 750, more preferably 2 to 500, even more preferably 3 to 300; parameter b is in the range of 0 to 1000, preferably 1 to 750, more preferably 2 to 500, even more preferably 3 to 300; the relative ratio of the parameters y:b is in the range of 1:0 to 1:3, preferably 2:1 to 1:2; M ｙ , J ２ and G are each independently CH ２ or C═O; Q represents a divalent alkyl, heteroalkyl, cycloalkyl, heterocycloalkyl, aryl, or heteroaryl residue; R ｙ represents the side chain S2 comprising the polymer moiety M2, preferably C １ ~C ８ -alkylene-Z-T, where Z represents C(=O)-O or a divalent N-containing heterocyclic residue, and T represents C １ ~C ４ - represents an alkylene residue to which a polystyrene moiety is attached, R ２ is C １ ~C ６ - alkyl residue, preferably branched C １ ~C ６ -representing an alkyl residue), Preferably, the first block B1 of the copolymer 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, the second block B2 of the copolymer comprises at least one structural unit SU2a represented by at least the substructure PS2a-1 and further comprises at least one structural unit SU2b represented by the substructure 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 the parameters x: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; 3. A multilayer coating system according to claim 1 or 2, wherein the relative ratio of the parameters y:b is in the range of 2:1 to 1:2, preferably 1.5:1 to 1:1.5, the remaining residues and variables having the meanings defined above in the claims.

15. 3. A multilayer coating system according to claim 1 or 2, wherein the at least one copolymer is present in the coating composition used to prepare the second coating layer L2 in an amount ranging from 10 to 100% by weight, preferably from 15 to 100% by weight, more preferably from 20 to 95% by weight, in each case based on the total solids content of the coating composition.

16. The coating composition comprising the at least one block copolymer used to prepare the second coating layer L2 further comprises at least one homopolymer, preferably selected from polyester, poly(meth)acrylate, polyether, polysiloxane and polystyrene homopolymer, more preferably selected from polystyrene, polyether and polyester homopolymers and mixtures thereof, even more preferably selected from polystyrene and aliphatic polyesters such as polylactide homopolymers and mixtures thereof, and the at least one homopolymer preferably has a number average molecular weight (M ｎ ) that is at least 100 times, preferably at least 150 times, more preferably at least 175 times lower than the number average molecular weight (M ｎ 3. A multi-layer coating system according to claim 1 or 2, comprising a copolymer and at least one homopolymer, and preferably the relative weight ratio of solids of said copolymer to solids of said at least one homopolymer in said 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, even more preferably from 85:15 to 20:80, even more preferably from 75:25 to 25:75, in particular from 60:40 to 30:

70.

17. 10. A multilayer coating system according to claim 1, wherein the coating composition comprising said at least one block copolymer used to prepare said second coating layer L2 comprises, besides said copolymer and, if such homopolymer is present, besides said at least one homopolymer as defined above in claim 13, at least one further resin, preferably at least one polymeric resin, and the relative weight ratio of the solids of said copolymer to the solids of said at least one further resin within said coating composition is preferably in the range from 5:95 to 100:0, more preferably from 10:90 to 100:0, even more preferably from 15:85 to 95:5, even more preferably from 20:80 to 90:10, even more preferably from 25:75 to 85:15, in particular from 30:70 to 80:20, and most preferably from 40:60 to 80:

20.

18. At least steps (1), (2), (3) and (4), 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 second base 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, preferably adjacent to the first coating film; (3) applying a coating composition different from the compositions applied in steps (1) and (2) to the second coating film present on the substrate obtained after step (2), to form a third coating film preferably adjacent to the second coating film, wherein the coating composition is preferably a clearcoat composition; and (4) simultaneously curing at least the second and third coating films applied in steps (2) and (3), and optionally the first coating film applied in step (1) if the first coating film has not been cured prior to performing step (2), to obtain a multi-layer coating system comprising at least first, second, and third coating layers L1, L2, and L3.

10. A method for preparing the multi-layer coating system of claim 1, comprising:

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

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