High-solids one-pack clearcoat compositions

Abstract

The invention relates to a solvent-borne one-pack clearcoat material, characterized in that it comprises one or more hydroxy functional polymers (A), at least one of which is a poly(meth)acrylate (A1), possessing a glass transition temperature below -15 °C as determined by differential scanning calorimetry; a hydroxyl value in the range from 130 mg KOH / g to 300 mg KOH / g; and a weight-average molecular weight in the range 2000 g / mol to 9000 g / mol determined by gel permeation chromatography using a polystyrene standard; two or more crosslinking agents (B), at least one of which is a melamine-formaldehyde resin possessing butoxymethyl groups and imino groups (B1); and at least one of which is a melamine-formaldehyde resin possessing methoxymethyl groups and imino groups (B2); and a catalyst comprising one or more amine-blocked sulfonic acids (C1). The invention further related to a multilayer coating system comprising a clearcoat layer formed from said clearcoat material, a method of preparing such multilayer coating system and a thus coated substrate, as well as the use of the solvent-borne one-pack clearcoat material for coating uncoated or precoated substrates, preferably vehicle bodies or parts thereof in OEM or repair coating.

Description

[0001] BASF Coatings GmbH Aug. 26, 2025

[0002] HIGH-SOLIDS ONE-PACK CLEARCOAT COMPOSITIONS

[0003] The present invention relates to a high-solids solvent-borne one-pack (1 K, one-component) clearcoat material comprising a poly(meth)acrylate with low glass transition temperature, low weight-average molecular weight, and high hydroxyl value, a methoxymethyl groups and imino groups comprising melamine-formaldehyde resin, a butoxymethyl groups and imino groups comprising melamine-formaldehyde resin and a catalyst comprising an amine-blocked sulfonic acid derivative. The invention further comprises a multilayer coating system, comprising at least one basecoat layer and at least one clearcoat layer, the clearcoat layer being formed from the clearcoat material of the invention, as well as a method for producing such multilayer coating system. Moreover, the invention relates to a thus coated substrate and the use of the clearcoat material of the invention in original manufacturer equipment (OEM) coating and refinish coating of vehicles.

[0004] BACKGROUND

[0005] Clearcoat materials are typically used to form the upper-most coating layer of multilayer coating systems. Since clearcoat layers are directly exposed to the environment, they need to provide several properties such as scratch resistance, weathering resistance, a good appearance, but also a good adhesion to coating layers underneath the clearcoat layer. Particularly high requirements on the quality of such clearcoat materials and the layers formed thereof are set by the automotive industry. Thus, there is a need to provide further improved clearcoat materials and multilayer coating systems comprising the same.

[0006] Moreover, nowadays, the increase of solids content in coating materials is a desired measure to reduce the emission of volatile organic compounds (VOC) and to thus improve the ecological footprint.

[0007] Another desire is to provide a one-component clearcoat composition, which is solvent-borne, and shows good adhesion, scratch resistance, hardness and stone-chip resistance on both, water-borne basecoats and solvent- borne basecoats, without deterioration of the appearance of the clearcoat layer, particularly the short-wave and long-wave levelling characteristics, and the distinctiveness of image.

[0008] While the clearcoat materials of the present invention should be designed to fulfill the needs of OEM automotive coating, the adhesion of the clearcoat material even in repair coating, should also be improved.

[0009] There are several approaches to use alkoxylated melamine-formaldehyde resins in solvent-borne one-pack clearcoat materials.

[0010] E.g., US 7,619,019 B2 relates to low bake, reactive one-component and two-component coating compositions for coating plastic substrates. More particularly, it relates to one-component, shelf-stable alkylether functional aminoplast resin cured coating compositions (methylated and butylated aminoplast resins), which can cure at BASF Coatings GmbH Aug. 26, 2025 temperatures ranging from 60 °C to 135 °C to form automotive basecoat, colorcoat or monocoat, topcoat and clearcoat finishes, as well as to the methods of making the compositions. All melamine-formaldehyde resins used therein are fully methoxymethylated or mixed (methoxy / butoxy)methylated. No imino group containing resins were used.

[0011] US 5,283,084 relates to processes for coating substrates and aims to utilize less organic solvent in coating substrates with a solvent-borne clearcoat composition over a water-borne basecoat composition. The solvent-borne clearcoat compositions used in the examples of US 5,283,084 comprise acrylic polymers having theoretical glass transition temperatures of +4 °C and above. The melamine-formaldehyde resins used therein are either mixed (methoxy / butoxy)methylated containing no imino groups, or partially etherified containing methylol groups.

[0012] WO 93 / 15849 describes catalyst-free clearcoat materials containing a melamine resin which is etherified with n- butanol. This document further discloses that it is particularly preferred that on average per triazine group of the melamine resin 0.1 to 0.25 nitrogen-bound hydrogen atoms should be comprised, that means that only each 4thto 10thtriazine group comprises an imino group. No mixtures of at least two melamine-formaldehyde resins are used.

[0013] WO 1994 / 022969 A1 discloses a clear coat composition containing an n-butylated high imino melamine resin, but makes also no use of mixtures of at least two melamine-formaldehyde resins and is silent on the use of any catalyst. Furthermore, the acrylic resin is only characterized by a wide range of hydroxyl numbers ranging from 60 to 200 mg KOH / g, in the example an acrylic resin with a calculated OH number of 130 mg KOH / g was used.

[0014] In WO 00 / 71630 a one-pack clearcoat (Example 2) is disclosed, which comprises a commercially available butanol- etherified melamine formaldehyde resin, nothing is known about whether this resin contains imino groups or methylol groups. The polyacrylates used in this example have rather low hydroxyl numbers of 99 and 113 mg KOH / g, respectively, and rather high calculated glass transition temperatures of -1.5 and +9.8 °C, respectively.

[0015] EP 1 538 172 A1 relates to one-pack clearcoats making use of mixtures of acrylic resins having a low glass transition temperature (-100 to -10 °C) with those having a high glass transition temperature (+20 to +70 °C). However, as crosslinking agents blocked polyisocyanates are mandatorily used and the use of melamine resins is discouraged.

[0016] EP 0 708 159 A2 discourages the use of fully methoxymethylated high imino melamine-formaldehyde resins (Cymel® 327 is comparative) in the one-pack clearcoat compositions, but uses instead only partially alkylated high- imino melamine resins, i.e., those comprising methylol groups. Furthermore, the clearcoat comprises a high amount of blocked isocyanates and a tin-based catalyst in combination with an acrylic resin, which is not further specified than bearing at least one reactive functionality. BASF Coatings GmbH Aug. 26, 2025

[0017] It was particularly an aim of the present invention to provide a solvent-borne one-pack clearcoat material, which overcomes the problems known from prior art, and which is suitable in OEM and repair coating, particularly automotive OEM coating and automotive repair coating.

[0018] The cured multilayer coating systems produced by use of the clearcoat material have a high-solids content and should show excellent appearance, particularly levelling characteristics, acid resistance, while providing scratch resistance, stone-chip resistance and possessing an excellent hardness and recoatability. Particularly, it was also an aim of the present invention to provide a high-solids one-pack clearcoat material, which allows for an improved balance between scratch resistance and recoatability of the cured clearcoat, particularly in multilayer coating systems, such as automotive coatings.

[0019] SUMMARY

[0020] To overcome the prior art drawbacks and to achieve the aims of the invention a solvent-borne one-pack clearcoat material is provided, which comprises

[0021] I. one or more hydroxy functional polymers (A), at least one of which is a poly(meth)acrylate (A1), possessing a. a glass transition temperature below -15 °C as determined by differential scanning calorimetry; b. a hydroxyl value in the range from 130 mg KOH / g to 300 mg KOH / g; and c. a weight-average molecular weight in the range of 2000 to 9000 g / mol determined by gel permeation chromatography using a polystyrene standard;

[0022] II. two or more crosslinking agents (B), at least one of which is a melamine-formaldehyde resin possessing butoxymethyl groups and imino groups (B1); and at least one of which is a melamine-formaldehyde resin possessing methoxymethyl groups and imino groups (B2); and ill. a catalyst comprising one or more amine-blocked sulfonic acids (C1).

[0023] This solvent-borne one-pack clearcoat material and its preferred embodiments are referred to hereinafter as "clearcoat material of the invention” or "clearcoat material according to the invention.”

[0024] A further subject matter of the present invention is a multilayer coating system, comprising a basecoat layer and a clearcoat layer on said basecoat layer, the clearcoat layer being formed by the clearcoat material of the invention.

[0025] This multilayer coating system and its preferred embodiments are referred to hereinafter as "multilayer coating system of the invention” or "multilayer coating system according to the invention.” BASF Coatings GmbH Aug. 26, 2025

[0026] Yet another subject matter of the present invention is a method for preparing a multilayer coating system, which at least comprises the following steps a. providing an uncoated or precoated substrate; b. applying at least one basecoat material on said substrate, thus forming a basecoat layer; and subsequently c. applying at least one clearcoat material on the only or the upper-most basecoat layer, thus forming at least one clearcoat layer; and d. curing any not yet cured layer, wherein the only or at least the upper-most clearcoat layer is formed from a clearcoat material of the invention.

[0027] This method for preparing a multilayer coating system and its preferred embodiments are referred to hereinafter as "method for preparing a multilayer coating system of the invention” or "method for preparing a multilayer coating system according to the invention.”

[0028] A further subject matter is a coated substrate, which is a metallic or polymeric substrate and comprises a multilayer coating system of the invention.

[0029] This coated substrate and its preferred embodiments are referred to hereinafter as "coated substrate of the invention” or "coated substrate according to the invention.”

[0030] Yet another subject matter of the invention is the use of a clearcoat material of the invention for coating an uncoated or precoated substrate, preferably the substrate being a vehicle body or part of a vehicle body, more preferably the substrate being an automotive vehicle body or a part of an automotive vehicle body.

[0031] This use and its preferred embodiments are hereinafter referred to as "use of the invention” or "use according to the invention.”

[0032] As a general remark, the term "comprising” as used in the present invention, is not limited to the meaning "comprising only” or "consisting of.” E.g. , in coating materials, it allows the presence of further ingredients, or with respect to substructures, such as residues of a chemical material, it allows the presence of further substructure, if not defined in a more limiting way. In a method comprising method steps, further method step may be comprised, too. However, in any case the term "comprising” also includes besides the broad meaning, also the limiting meaning of "comprising only” and "consisting of.” BASF Coatings GmbH Aug. 26, 2025

[0033] DETAILED DESCRIPTION

[0034] Solvent-borne one-pack clearcoat material

[0035] A "coating material” according to EN ISO 4618:2006 is a product, in liquid, paste or powder form, that, when applied to a substrate, forms a film possessing protective, decorative and / or other specific properties. A "clear coating material” - according to the same standard - is a coating material which when applied to a substrate forms a solid transparent film having protective, decorative or specific technical properties.

[0036] In a "one-pack coating material” of any kind the binder to be cured and the crosslinking agent curing the binder are supplied not separately, but mixed in one coating material, without the components reacting prematurely with each other.

[0037] The clearcoat material of the present invention is liquid at room temperature (i.e. , 25 °C) and essentially consists of binders and volatile ingredients (i.e., volatile solvents). The term "binder,” according to EN ISO 4618:2006 (German version), is the non-volatile part of a medium without pigments and fillers. Since clearcoat compositions typically do not contain significant amounts of pigments and / or filler, and preferable do not contain pigments and fillers at all, the binder content of the clearcoat material of the invention preferably equals the solids content. The solids content (in wt.-%) (non-volatile content or theoretical solids content) was calculated by subtracting the amount(s) of any organic solvents from the total weight of the respective product in question, dividing the resulting weight by the total weight of the respective product itself, and multiplying the thus obtained result by 100. The difference to 100 wt.-% is the volatile content of the sample. The binder content (in wt.-%) (non-volatile content) was calculated by subtracting the amount(s) of any solvents, pigments and fillers from the total weight of the respective product in question, dividing the resulting weight by the total weight of the respective product itself, and multiplying the thus obtained result by 100.

[0038] The term "melamine-formaldehyde resin” is often also denoted as "melamine resin” and encompasses monomeric melamine-formaldehyde resins and their oligomers, such as dimers, trimers and tetramers and higher oligomers.

[0039] According to the above definition of the term "binder,” also includes crosslinking agents (B), as well as the catalyst system (C); and any other coatings additives (D) differing from (A), (B) and (C).

[0040] The term "solvent-borne” in conjunction a coating material means that preferably the main part i.e., at least 50 wt.- %, more preferably at least 70 wt.-%, even more preferred at least 90 wt.-%, and most preferred at least 95 or 98 wt.-%, such as 100 wt.-% of the volatile content of the coating material consists of organic solvents. BASF Coatings GmbH Aug. 26, 2025

[0041] Solvent-borne one-pack clearcoat material preferably possesses a theoretical solids content in the range from 40 to 70 wt.-%, more preferred from 45 to 65 wt.-% and most preferred from 50 to 70 wt.-%; and / or a theoretical solids content in the range from 35 to 65 wt.-%, more preferred from 40 to 60 wt.-% and most preferred from 45 to 65 wt.- %, if the viscosity of the solvent-borne one-pack clearcoat material is adjusted to a viscosity resulting in a flow time of 46 seconds using an AFNOR viscosity flow cup No. 4 at 23 °C (in accordance with French standard NF T 30- 014). Preferably, viscosity adjustment is carried out by addition of one or more organic solvents, preferably xylene, to obtain the aforementioned viscosity, which is a preferred spraying viscosity.

[0042] The hydroxy-functional polymers (A) comprise at least one poly(meth)acrylate (A1) as defined herein below, but may also comprise further hydroxy-functional polymers (A), preferably from the group consisting of poly(meth)acrylates (A2), which do not fulfill the requirements of (A1) regarding to at least one of the parameters glass transition temperature, hydroxyl value and weight-average molecular weight; polyesters (A3); and further hydroxy-functional polymers (A4) not belonging to poly(meth)acrylates (A1) and (A2) or polyesters (A3).

[0043] The glass transition temperature (Tg) for the purposes of the invention for any hydroxyl functional polymer (A) is determined experimentally in a method based on DIN 51005 "Thermal Analysis (TA) Terms” and DIN 53765 "Thermal Analysis— Dynamic Scanning Calorimetry (DSC)'. This method is described in detail in the Experimental Section of the description.

[0044] The hydroxyl number (hydroxyl value) or OH number (OH value) for any of the hydroxy-functional polymers (A) indicates the amount of potassium hydroxide in milligrams that is equivalent to the molar amount of acetic acid bound on acetylation of one gram of the respective constituent. In the context of the present invention, unless indicated otherwise, the hydroxyl number for any hydroxyl functional polymer is determined as described in detail in the Experimental Section of the description.

[0045] The weight-average molecular weight Mwof all hydroxy-functional polymers (A) is determined by means of gel permeation chromatography as described in detail in the Experimental Section of the description.

[0046] The combined solids amount of hydroxy-functional polymers (A), based on the total solids amount of the clearcoat composition of the present invention is preferably in the range of 50 wt.-% to 75 wt.-%, more preferred 55 to 70 wt.- % and most preferred 58 wt.-% to 68 wt.-%. BASF Coatings GmbH Aug. 26, 2025

[0047] Hydroxy-functional Polv(meth)acrylates (A1)

[0048] The solvent-borne one-pack clearcoat material of the invention contains one or more hydroxy functional polymers selected from poly(meth)acrylates (A1) possessing a glass transition temperature below -15 °C as determined by DSC measurement; a hydroxyl value in the range from 130 mg KOH / g to 300 mg KOH / g; and a weight-average molecular weight determined by gel permeation chromatography using a polystyrene standard in the range from 2000 to 9000 g / mol.

[0049] Poly(meth)acrylates (A1) and also (A2) comprise (meth)acrylic monomers. The term "(meth)acrylic” encompasses the terms "acrylic,” and "methacrylic,” while the term "(meth)acrylate” encompasses the terms "acrylate” and "methacrylate.”

[0050] A poly(meth)acrylate as to be generally understood in the present invention for both, poly(meth)acrylates (A1) and (A2), comprises as (meth)acrylic monomers, preferably esters of (meth)acrylic acid. They may also contain to a preferably low amount (meth)acrylic acid. However, a poly(meth)acrylate of the present invention may further comprise non-(meth)acrylic monomers such as vinyl group containing monomers like styrene. Preferably, a poly(meth)acrylate according to the present invention comprises, based on the total weight of the monomers used for its production at least 50 wt.-%, more preferably at least 55 wt.-% of (meth)acrylic monomers, in case of poly(meth)acrylates (A1) even more preferably at least 60 wt.-%, further preferred at least 70 wt.-%, 80 wt.-% or most preferred at least 85 wt.-% of (meth)acrylic monomers.

[0051] The preparation of the poly(meth)acrylates (A1), but also (A2) has no technical peculiarities in terms of process, but instead is accomplished, for example, with the aid of the methods, customary and known within the field of the art, of continuous or batchwise, free-radically initiated (co)polymerization in bulk, solution, emulsion, miniemulsion or microemulsion, under atmospheric or superatmospheric pressure, in stirred tanks, autoclaves, tube reactors, loop reactors or Taylor reactors, at temperatures of specifically 50 to 200 °C. Examples of suitable polymerization processes are described in patent applications DE 19709 465 A 1 ,

[0052] DE 197 09 476 A1 , DE 28 48 906 A1 , DE 195 24 182 A1 , DE 198 28 742 A1 , DE 196 28 143 A 1 , DE 196 28 142 A 1 , EP 0 554 783 A 1 , WO 95 / 27742 A1 , WO 82 / 02387 A1 or WO 98 / 02466 A 1. The polymerization may alternatively be carried out in polyols (thermally curable reactive diluents) as reaction medium, as described in German patent application DE 198 50 243 A 1 , for example. Examples of suitable free-radical initiators are dialkyl peroxides, such as di-tert-butyl peroxide or dicumyl peroxide, hydroperoxides, such as cumene hydroperoxide or tert-butyl hydroperoxide, peresters, such as tert-butyl perbenzoate, tert-butyl perpivalate, tert-butyl per-3, 5,5- trimethylhexanoate or tert-butyl per-2-ethylhexanoate, peroxodicarbonates, potassium, sodium or ammonium peroxodisulfate, azo initiators, examples being azodinitriles such as azobisisobutyronitrile, C-C-cleaving initiators such as benzpinacol silyl ethers, or a combination of a nonoxidizing initiator with hydrogen peroxide. Combinations of the above-described initiators may also be employed. BASF Coatings GmbH Aug. 26, 2025

[0053] The at least one poly(meth)acrylate (A1) has a glass transition temperature Tgof preferably in the range from -60 °C to -15 °C, more preferably from -50 °C to -18 °C, even more preferred from -40 °C to -20 °C. In case the Tgis higher than -15 °C, the viscosity tends to be too high and scratch resistance is reduced. In case the Tgis below - 60 °C the cured coating tends to lack hardness. As the skilled person in the field is aware, the glass transition temperature of the poly(meth)acrylate (A1) is defined, for example, through the nature of the monomers present and through their proportions in the polymer. A corresponding selection may be made by the skilled worker without substantial effort. In literature there are comprehensive tables of glass transition temperature determined for homopolymers of polymerized monomers. Selecting monomers, the homopolymers of which have low glass transition temperatures leads to the desired poly(meth)acrylates (A1) having Tgvalues in the afore-mentioned ranges. As a good estimation the use of acrylic monomers typically lead to lower glass transition temperatures than the use of methacrylic monomers. And reducing the weight-average molecular weight within the required ranges also typically leads to lower glass transition temperatures.

[0054] The at least one poly(meth)acrylate (A1) has a hydroxyl value of at least 130 mg KOH / g and at most 300 mg KOH / g, preferably a hydroxyl value in the range from 140 or 150 mg KOH / g to 300 mg KOH / g, even more preferred in the range from 155 mg KOH / g to 250 mg KOH / g, further preferred in the range from 160 mg KOH / g to 220 mg KOH / g, and most preferred in the range from 170 to 200 mg KOH / g. In case the hydroxyl value exceeds 300 mg KOH / g, the scratch resistance tends to decrease. The same is the case when the hydroxyl value falls below 130 mg KOH / g. To obtain a poly(meth)acrylate (A1) having the desired hydroxyl value, the amount of hydroxy group comprising monomers, such as the hydroxyalkyl (meth)acrylates can be varied. Preferably, based on the total weight of monomers of the monomer mixture employed in the production of the poly(meth)acrylate (A1), an amount of at least 25 wt.-% of hydroxyalkyl (meth)acrylates, more preferred 30 wt.-% of hydroxyalkyl (meth)acrylates to 50 wt.- %, and even more preferred 32 wt.-% to 45 wt.-% and most preferred 34 wt.-% to 40 wt.-% of hydroxyalkyl (meth)acrylates should be employed.

[0055] The at least one poly (meth)acryl ate (A1) has a weight-average molecular weight of at least 2000 g / mol and at most 9000 g / mol, preferably a weight-average molecular weight in the range from 3000 g / mol to 9000 g / mol, even more preferred in the range from 3500 to 6000 g / mol, further preferred in the range from 3800 to 5500 g / mol, and most preferred in the range from 4000 to 5000 mg KOH / g. In case the weight-average molecular weight exceeds 9000 g / mol, the viscosity tends to increase too much. If the weight-average molecular weight falls below 2000 g / mol the crosslinking density tends to drop and the performance of the cured coating tends to deteriorate, particularly the scratch resistance. BASF Coatings GmbH Aug. 26, 2025

[0056] Monomers used to prepare the poly(meth)acrylate (A1)

[0057] Examples of (meth)acrylate monomers include various alkyl (meth)acrylates (the term "alkyl” as used in the present invention always encompasses "linear alkyl,” "branched alkyl” and “cycloalkyl”), preferably Ci-C2o-alkyl (meth)acrylates, more preferred C2-Cis-alkyl (meth)acrylates. Preferred examples are methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, tertbutyl (meth)acrylate, amyl (meth)acrylate, hexyl (meth)acrylate, ethylhexyl (meth)acrylate, 3,3,5-trimethylhexyl (meth)acrylate, stearyl (meth)acrylate, lauryl (meth)acrylate, cyclopentyl (meth)acrylate, isobornyl (meth)acrylate, and cyclohexyl (meth)acrylate.

[0058] Since the poly(meth)acrylates (A1) and (A2) are hydroxy-functional, a certain fraction of hydroxy-functional monomers needs to be comprised in the monomer mixture used to form the poly(meth)acrylates (A1) and (A2). Hydroxy-functional (meth)acrylate monomers include hydroxyalkyl (meth)acrylates, such as, for example, 2- hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate.

[0059] Further monomer units used in the monomer mixture to form the poly(meth)acrylates (A1) and (A2) may be vinylaromatic hydrocarbons, Such as vinyltoluene, alpha-methylstyrene or, in particular, styrene, amides or nitriles of acrylic or methacrylic acid, vinyl esters or vinyl ethers, and also, if at all, in minor amounts, acrylic and / or methacrylic acid. Preferably not (meth)acrylic acid monomers are used in the monomer mixtures used to form the poly(meth)acrylates (A1) and (A2). If carboxylic acid groups are contained in the poly(meth)acrylate (A1), it is preferred the acid value of the poly(meth)acrylate (A1) is less than 15 mg KOH / g, such as from 0 mg KOH / g to 15 mg KOH / g, even better less than 12 mg KOH / g, such as 0 or 1 mg KOH / g to 12 mg KOH / g, or even still more preferred from 0 or 1 mg KOH / g to 10 mg KOH / g.

[0060] Amounts of poly(meth)acrylate (A1) in the clearcoat material of the invention

[0061] The amount of poly(meth)acrylates (A1), based on the total solids content of the clearcoat material of the invention, is preferably at least 30 wt.-% more preferred at least 34 wt.-%, and most preferred at least 38 wt.-%, such as at least 40 wt.%. Preferably the amount of poly(meth)acrylates (A1), based on the total solids content of the clearcoat material of the invention, is at most 60 wt.-% more preferred at most 55 wt.-%, and most preferred at most 50 wt- %, such as at most 45 wt.-%. Preferably the amount of poly(meth)acrylates (A1), based on the total solids content of the clearcoat material of the invention in the range from 30 to 60 wt.-%, more preferred in the range from 34 to 55 wt.-% and even more preferred in the range from 38 to 50 wt.-%, such as in the range from 40 to 45 wt.-%. BASF Coatings GmbH Aug. 26, 2025

[0062] Hydroxy-functional Poly(meth)acrylates (A2)

[0063] The presence of other poly(meth)acrylates (A2), differing from poly(meth)acrylates (A1) is not mandatory, e.g. 0 wt.-% based on total solids of the clearcoat material, but their presence may be preferred, particularly if used as part of rheology control compositions that are optionally employed into the clearcoat material of the invention. However, poly(meth)acrylates (A2) can also be employed without being part of a rheology control compositions, as such or in combination with other ingredients.

[0064] In general, the same manufacturing methods and monomers as disclosed for poly(meth)acrylates (A1) are used to produce poly(meth)acrylates (A2). However, poly(meth)acrylates (A2) differ in at least one of the ranges for the glass transition temperature, the hydroxyl value or the weight-average molecular weight from those ranges described above for the poly(meth)acrylates (A1).

[0065] Poly(meth)acrylates (A2) preferably have a glass transition temperature of more than -15 °C and up +80 °C, more preferably a glass transition temperature of -14 °C to +80 °C, even more preferred in the range from -14 °C to +75 °C.

[0066] Poly(meth)acrylates (A2) preferably have a hydroxyl number in the range from 50 to 250 mg KOH / g, more preferably in the range from 80 to 200 mg KOH / g, even more preferred in the range from 90 mg KOH / g to 180 mg KOH / g.

[0067] Poly(meth)acrylates (A2) preferably have a weight-average molecular weight in the range from 3000 to 30000 g / mol, more preferably in the range from 3500 to 25000 g / mol, even more preferred in the range from 4000 mg KOH / g to 20000 mg g / mol, determined in the same way as for poly(meth)acrylates (A1).

[0068] Poly(meth)acrylates (A2) may be employed in the clearcoat material of the invention in form of solutions and / or dispersions thereof in organic solvents, wherein the solutions and / or dispersions may contain coating additives (D), such as e.g., rheology control agents like urea crystals and / or silica particles, preferably hydrophobic silica particles.

[0069] Amounts of poly(meth)acrylate (A2) in the clearcoat material of the invention

[0070] The amount of poly(meth)acrylates (A2), based on the total solids content of the clearcoat material of the invention, is, if contained, preferably at least 5 wt.-% more preferred at least 7 wt.-%, and most preferred at least 10 wt.-%, such as at least 12 wt.%. Preferably the amount of poly(meth)acrylates (A2), based on the total solids content of the clearcoat material of the invention, is at most 30 wt.-% more preferred at most 25 wt.-%, and most preferred at most 22 wt.-%, such as at most 20 wt.-%. Preferably the amount of poly(meth)acrylates (A2), based on the total solids content of the clearcoat material of the invention in the range from 5 to 30 wt.-%, more preferred in the range BASF Coatings GmbH Aug. 26, 2025 from 7 to 25 wt.-% and even more preferred in the range from 10 to 22 wt.-%, such as in the range from 12 to 20 wt.-%.

[0071] Hydroxy-functional Polyester (A3)

[0072] The clearcoat material of the invention may further comprise a polyester (A3). While polyester (A3) can be formed, e.g., ring-opening reactions of one or more lactones, it is preferred that the polyester (A3) used in the invention is a polymeric reaction product obtained by reaction of one or more organic polyols and one or more polybasic organic carboxylic acids or the at least partial anhydrides of the polybasic organic carboxylic acids.

[0073] These polyols and polycarboxylic acids or their anhydrides are linked to one another by esterification.

[0074] Depending on nature, functionality, fractions used, and proportions of the starting components, linear or branched products, for example, are obtained. Whereas linear products come about primarily when using difunctional starting components (diols, dicarboxylic acids and their anhydrides), the use of higher polyfunctional alcohols (OH functionality, in other words number of OH groups per molecule, of more than 2), for example, brings about branching. In the course of the preparation it is, naturally, also possible to make proportional use of monofunctional components, such as monocarboxylic acids, for example. As explained above, polyesters may also be prepared using, instead of or in addition to the corresponding organic carboxylic acids, the anhydrides of the carboxylic acids, more particularly the anhydrides of dicarboxylic acids. Likewise possible is preparation through the use of hydroxycarboxylic acids or the lactones derived from the hydroxycarboxylic acids by intramolecular esterification, which however is not preferred in the present invention.

[0075] Generally, in the preparation of polyesters, it is possible to employ polycarboxylic acids and polyols, for example aliphatic polycarboxylic acids and aliphatic polyols. Likewise possible for use are aromatic polycarboxylic acids and aromatic polyols, or else polycarboxylic acids and polyols which in addition to the functional groups which identify their class of compound contain not only (linear, branched and / or cyclic) aliphatic but also aromatic groups. Also possible is the use of linear, branched and / or cyclic aliphatic and / or aromatic hydroxycarboxylic acids and also lactones, in other words hydroxycarboxylic acids and lactones which, in addition to the functional groups which identify their class of compound, have linear, branched and / or cyclic aliphatic and / or aromatic groups.

[0076] Suitable diols are, for example, alkylene glycols, such as ethylene glycol, propylene glycol, butylene glycol, butane-1 ,4-diol, hexane-1 ,6-diol, neopentyl glycol, and other diols, such as 1 ,4-dimethylolcyclohexane or 2-butyl- 2-ethyl-1 ,3-propanediol. Suitable higher polyfunctional alcohols (OH functionality more than 2) are, for example, trimethylolpropane, glycerol, and pentaerythritol. BASF Coatings GmbH Aug. 26, 2025

[0077] The acid component of a polyester generally comprises dicarboxylic acids having 2 to 44, specifically 4 to 36, carbon atoms in the molecule. Examples of suitable acids are o-phthalic acid, isophthalic acid, terephthalic acid, tetrahydrophthalic acid, hexahydrophthalic acid, cyclohexanedicarboxylic acid, succinic acid, adipic acid, azelaic acid, sebacic acid, maleic acid, fumaric acid, glutaric acid, hexachloroheptanedicarboxylic acid, tetrachlorophthalic acid and / or dimerized fatty acids. In place of the acids, it is also possible to use their anhydrides, where they exist, for preparing the polyesters. Specifically, however, isophthalic acid and / or hexahydrophthalic acid, and also the anhydride of hexahydrophthalic acid, are used for preparing the polyesters. Especially preferred is the use of hexahydrophthalic acid and the anhydride of hexahydrophthalic acid. The polyesters therefore comprise the stated preferred dicarboxylic acids as monomer units. It is also possible to use higher polyfunctional carboxylic acids having 3 or more carboxyl groups (and / or the corresponding anhydrides), an example being trimellitic anhydride. Frequently use is also made, proportionally, of monocarboxylic acids, such as unsaturated fatty acids, for example.

[0078] Examples of hydroxycarboxylic acids which can be used are hydroxycaproic acid, hydroxybutyric acid, hydroxydecanoic acid and / or 12-hydroxystearic acid. Examples of lactones which can be employed are the conventional beta-, gamma-, delta-, and epsilon-lactones, more particularly epsilon-caprolactone.

[0079] Besides the above-described monomeric compounds it is also possible, for example, to use starting products which are already polymeric, for example, as diols, the conventional polyester diols obtained by reacting a lactone with a dihydric alcohol.

[0080] The hydroxy-functional polyester (A3) preferably has a hydroxyl value in the range from 50 to 350 mg KOH / g, more preferably in the range from 100 to 320 mg KOH / g, even more preferred in the range from 150 to 300 mg KOH / g, and most preferred in the range from 200 to 280 mg KOH / g.

[0081] The polyester (A3) preferably possesses a glass transition temperature in the range from -60 °C to -10 °C, more preferably from -50 °C to -15 °C, even more preferred from -40 °C to -20 °C.

[0082] The polyesters (A3) are preferably of low weight-average molecular weight, particularly preferred they possess a weight-average molecular weight in the range from 1000 to 6000 g / mol, more preferred in the range from 1500 to 5000 g / mol, even more preferred in the range from 1800 to 4000 g / mol, and most preferred in the range from 2000 to 3000 g / mol.

[0083] Preferably polyester (A3) is aliphatic. Preferably the polyester (A3) is branched. Most preferred polyester (A3) is an aliphatic and branched polyester.

[0084] The preparation of polyesters has no peculiarities in terms of process, and takes place generally via the conventional and known polymerization processes, more particularly polycondensation processes, in bulk, solution, BASF Coatings GmbH Aug. 26, 2025 emulsion, miniemulsion or microemulsion, in stirred tanks, autoclaves, tube reactors, loop reactors or Taylor reactors, at temperatures of specifically 50 to 300 °C, using, where appropriate, the catalysts typical for such reactions, and / or the water separators that are typically employed for condensation reactions.

[0085] The amount of polyester (A3), based on the total solids content of the clearcoat material of the invention, may be 0 wt.-%, but preferably is at least 2 wt.-% more preferred at least 4 wt.-%, and most preferred at least 6 wt.-%, such as at least 7 wt.%. Preferably the amount of polyesters (A3), based on the total solids content of the clearcoat material of the invention, is at most 20 wt.-% more preferred at most 15 wt.-%, and most preferred at most 12 wt- %, such as at most 10 wt.-%. Preferably the amount of polyester (A3), based on the total solids content of the clearcoat material of the invention in the range from 2 to 20 wt.-%, more preferred in the range from 4 to 15 wt.-% and even more preferred in the range from 6 to 12 wt.-%, such as in the range from 7 to 10 wt.-%.

[0086] Hydroxy-functional Polymers (A4) other than (A1), (A2) and (A3)

[0087] The clearcoat material of the invention may further contain hydroxy-functional polymers (A4) other than poly(meth)acrylates (A1) and (A2) and polyesters (A3).

[0088] Such polymers (A4) are, e.g., alkyds, polyurethanes, polycarbonates, polyethers, epoxy resin-amine adducts, polyureas, polyamides, polyimides, polyester-polyurethanes, polyether-polyurethanes or polyester-polyether- polyurethanes.

[0089] However, if contained at all, it is preferred that their amount, based on the solids content of the clearcoat material of the invention is at most 10 wt.-%, such as 0 to 10 wt.-%, more preferred 0 to 8 wt.-%, even more preferred 0 to 6 wt.-%. The lower amount of the afore-mentioned ranges is 0 wt.-%, but may also be 1 or 2 wt.-%.

[0090] Crosslinking Agent (B)

[0091] (B1) Melamine-formaldehyde resin possessing butoxymethyl Groups and Imino Groups

[0092] Melamine has the following structure:

[0093] As an example, a monomeric melamine-formaldehyde resins can be depicted by the following formula: BASF Coatings GmbH Aug. 26, 2025 wherein one to all residues R = CH2-OH (this group originates from formaldehyde and is also called methylol group). Oligomeric melamine-formaldehyde resins are bridged via linking groups between nitrogen atoms of the substituents.

[0094] If only one of the two R groups bound to a nitrogen is R = CH2-OH or CH2-O-alky I (see below) and the other R = H a group NHR with R = CH2-OH or CH2-O-alkyl is formed, which is called an imino group.

[0095] Further, if methylol groups (CH2-OH) are alkylated, groups R = CH2-O-alkyl are formed, e.g., alkyl being methyl or butyl, such as n-butyl or iso-butyl.

[0096] Consequently, R can be H, CH2-OH or CH2-O-alkyl.

[0097] Crosslinking agent (B1) is a melamine-formaldehyde resin possessing butoxymethyl groups (CH2-0-butyl) and imino groups. Crosslinking agent (B1) preferably comprises no other alkoxy alkyl group than butoxymethyl groups. The term "butoxymethyl” always encompasses "n-butoxymethyl” and "iso-butoxymethyl”, whereas for all embodiments n-butoxymethyl is preferred.

[0098] Particularly preferred, the crosslinking agent (B1) possesses only imino groups and butoxymethyl groups. Most preferably, the methylol groups are fully butylated. Thus, most preferably the crosslinking agent does not possess -CH2-OH groups. With other words, it is preferred that in all -CH2-OR' groups present in the crosslinking agent (B1) residue R' = butyl and not H. However, at most 5 mole-% of residues R' may be H and 95 mole-% are butyl, more preferred at most 3 mole-% of residues R' may be H and 97 mole-% are butyl, and even more preferred at most 1 mole-% of residues R' may be H and 99 mole-% are butyl.

[0099] If the crosslinking agent (B1) comprises oligomers or the afore-mentioned monomeric butylolated melamines, such as dimers, trimers or tetramers, thereof, the monomers may be linked to each other by a condensation reaction of two methylol groups, e.g., as follows:

[0100] -CH2-OH + HO-CH2- -> -CH2-O-CH2- + H2O. The thus formed -CH2-O-CH2- group may further react as follows: - CH2-O-CH2- -> -CH2- + CH2O. BASF Coatings GmbH Aug. 26, 2025

[0101] The amount of crosslinking agent (B1) is, based on the total solids content, preferably in the range from 8 to 25 wt.- %, more preferred 10 to 20 wt.-%, even more preferred 12 to 18 wt.-%, and most preferred in the range from 14 to 16 wt.-%.

[0102] It is highly preferred that the weight ratio of the solids content of crosslinking agent (B1) to the solids content of the hydroxy-functional polymers (A) is in the range from 7:93 to 34:66, more preferred in the range from 13:87 to 27:73, even more preferred in the range from 17:83 to 24:76.

[0103] (B2) Melamine-formaldehyde resin possessing methoxymethyl groups and imino groups

[0104] The same applies for crosslinking agents (B2) as was described for crosslinking agent (B1), the only difference is that instead of -CH2-O-butyl groups, -CH2-O-CH3 groups are present, and preferably no other alkoxy alkyl groups than methoxymethyl groups are present. Thus, (B1) and (B2) differ from each other.

[0105] Thus, crosslinking agent (B2) is a melamine-formaldehyde resin possessing methoxymethyl groups (-CH2-O-CH3) and imino groups.

[0106] Particularly preferred, the crosslinking agent (B2) possesses only imino groups and methoxymethyl groups. Most preferably, the methylol groups are fully methylated. Thus, most preferably the crosslinking agent does not possess -CH2-OH groups. With other words, it is preferred that in all -CH2-OR' groups present in the crosslinking agent (B2) residue R' = methyl and not H. However, at most 5 mole-% of residues R' may be H and 95 mole-% are methyl, more preferred at most 3 mole-% of residues R' may be H and 97 mole-% are methyl, and even more preferred at most 1 mole-% of residues R' may be H and 99 mole-% are methyl.

[0107] If the crosslinking agent (B2) comprises oligomers or the afore-mentioned monomeric methylolated melamines, such as dimers, trimers or tetramers, thereof, the monomers may be linked to each other by a condensation reaction of two methylol groups, e.g., as follows:

[0108] -CH2-OH + HO-CH2- -> -CH2-O-CH2- + H2O. The thus formed -CH2-O-CH2- group may further react as follows: - CH2-O-CH2- -> -CH2- + CH2O.

[0109] The amount of crosslinking agent (B2) is, based on the total solids content, preferably in the range from 8 to 25 wt.- %, more preferred 10 to 20 wt.-%, even more preferred 12 to 18 wt.-%, and most preferred in the range from 14 to 16 wt.-%.

[0110] It is highly preferred that the weight ratio of the solids content of crosslinking agent (B2) to the solids content of the hydroxy-functional polymers (A) is in the range from 7:93 to 34:66, more preferred in the range from 13:87 to 27:73, even more preferred in the range from 17:83 to 24:76. BASF Coatings GmbH Aug. 26, 2025

[0111] Amounts of(B1) and (B2)

[0112] It is preferred that the total amount of melamine-formaldehyde resins (B1) plus (B2), based on the total solids content, is in the range from 20 to 40 wt.-%, more preferably 23 to 37 wt.-% and most preferred 26 to 34 wt.-%, such as 28 to 32 wt.-%.

[0113] If the total amount of melamine-formaldehyde resins (B1) plus (B2), based on the total solids content, exceeds 40 wt.-% the repair adhesion tends to decrease, and if it drops below 20 wt.-% the clearcoat hardness tends to decrease.

[0114] It is preferred that the weight ratio of melamine-formaldehyde resins (B1) to melamine-formaldehyde resins (B2) is in the range from 1 :99 to 99:1 , more preferred in the range from 20:80 to 80:20, even more preferred 30:70 to 70:30, particularly preferred 40:60 to 60:40 and most preferred in the range from 45:55 to 55:45.

[0115] The more of the melamine-formaldehyde resins (B1) are used, the more the solids content of the clearcoat material tends to decrease due to practical reasons, and the more of the melamine-formaldehyde resins (B2) are used, the more the repair adhesion tends to decrease.

[0116] (B3) Blocked Polyisocyanate

[0117] The clearcoat material of the invention optionally contains one or more blocked polyisocyanates. In the context of the present invention, the term blocked polyisocyanates is understood to mean those polyisocyanates that have at least two blocked isocyanate groups. A blocked isocyanate group is understood to mean an isocyanate group that has been blocked or capped by addition reaction onto what is called a blocking agent and wherein the addition reaction is reversible at higher temperatures, optionally using suitable catalysts.

[0118] Blocked polyisocyanates (B3) in the context of this invention - and as is customary in the field of coating compositions - do not comprise any free isocyanate groups and should thus be regarded, as far as technically possible, as 100% blocked polyisocyanates.

[0119] The free polyisocyanates used for preparation of the blocked polyisocyanates (B3) for use in accordance with the invention can be described by the following general formula (I):

[0120] R1-[NCO]n(I) in which BASF Coatings GmbH Aug. 26, 2025

[0121] R1is an organic radical free of organic NCO groups and comprising at least one aromatic hydrocarbon radical or at least one aliphatic hydrocarbon radical, preferably an aliphatic hydrocarbon radical, and optionally one or more groups selected from the group consisting of isocyanurate groups, iminooxadiazinedione groups, uretdione groups, allophanate groups, biuret groups, urethane groups, urea groups, ether groups and ester groups; and n is 2 to preferably 10, preferably 3 to 8, more preferably 3 to 6.

[0122] Preferably the polyisocyanate of formula (I) is an oligomer formed by oligomerization of an aromatic or aliphatic diisocyanate, more preferred from an aliphatic diisocyanate, most preferred a diisocyanate selected from the groups consisting of hexamethylene diisocyanates (HDI) and isophorone diisocyanates (IPDI). Such oligomers preferably contain one or more groups selected from the group consisting of isocyanurate groups, iminooxadiazinedione groups, uretdione groups, allophanate groups and biuret groups, even more preferred isocyanurate groups or iminooxadiazinedione groups. The oligomerization products may be formed by oligomerization of two, three or more diisocyanates, which can be same or different.

[0123] Preferred blocking agents for blocking the polyisocyanates of formula (I) are dimethylpyrazole, esters of malonic acid, or esters of other CH-acidic compounds like esters of acetoacetic acid.

[0124] The amount of crosslinking agent (B3) is, based on the total solids content, is preferably in the range from 0 to 20 wt.-%, more preferred 2 to 18 wt.-%, even more preferred 4 to 16 wt.-%, and most preferred in the range from 6 to 14 wt.-%.

[0125] (B4) Further Crosslinking Agents

[0126] It is possible to employ further crosslinking agents, which differ from crosslinking agents (B1), (B2) and (B3). Of course, such further crosslinking agents, if used, need to be compatible with the concept of a one-pack coating material, i.e., they should not negatively affect storage-stability of the one-pack material by, e.g., initiating premature crosslinking. Thus, they do preferably not possess free isocyanate groups.

[0127] Such further crosslinking agents may be selected from the groups of aminoplast resins other than the above melamine-formaldehyde resin possessing no imino groups and / or possessing methylol groups.

[0128] However, in the context of the present invention, it is preferred that no crosslinking agents (B4) are employed, i.e. the clearcoat material of the invention does not contain crosslinking agents (B4). In case further crosslinking agents (B4) are employed, their content should preferably not exceed 25 wt.-%, based on the combined solids contents of crosslinking agents (B1), (B2) and (B4). More preferably it should be in the range from 0 to 20 wt.-%, even more preferred in the range of 2 to 18 wt.-%, and most preferred in the range from 5 to 10 wt.-%, based on the combined solids contents of crosslinking agents (B1), (B2), (B3) and (B4). BASF Coatings GmbH Aug. 26, 2025

[0129] Catalysts (C)

[0130] The present invention mandatorily requires the use of a catalyst comprising at least one catalyst selected from amine-blocked sulfonic acids (C1) and preferably comprising at least one catalyst selected from non-blocked or at least partially amine-blocked phosphoric acid catalysts (C2).

[0131] The term "amine-blocked,” when used alone, is in accordance with the typical use in this technical field to be understood as "fully amine-blocked.” The term "at least partially amine-blocked,” when used in this technical field is to be understood in that some, but not all acid functionalities may be non-blocked. However, this term also includes the possibility that the respective acidic functionalities are "fully amine-blocked.” Furthermore, the terms "sulfonic acids” and "phosphoric acids” include - also in accordance with the typical denomination in this field organosulfonic acids, such as dodecylbenzene sulfonic acid, and organophosphoric acids, such as monophenyl phosphoric acid

[0132] The catalysts catalyze the curing of crosslinking agents (B1) and (B2) with the hydroxy functional polymers (A).

[0133] Amine-blocked sulfonic acids (01)

[0134] The amine-blocked sulfonic acids (C1) are preferably amine-blocked alkylaromatic sulfonic acids, more preferred amine-blocked alkylbenzene sulfonic acids, even more preferred amine-blocked Ci-C2o-alkylbenzene sulfonic acids, such as amine-blocked methylbenzene sulfonic acid (such as amine-blocked para-toluene sulfonic acid) and amine-blocked dodecylbenzene sulfonic acid. The alkyl of the alkylbenzene can be linear or branched. Such amine- blocked sulfonic acids and their manufacture are, e.g., described in US 4,812,506 A.

[0135] The amine with which the sulfonic acids are blocked are preferably selected from the group of amino alcohols, primary amines, secondary amines, and tertiary amines. Examples for suitable amines are 2-amino-2-methyl-1- propanol (AMP), diethylmethanol amine, methyl diethanol amine, ethyl diethanol amine, dimethylethanol amine, diisopropyl amine, diisopropanol amine, tris-ethylhexyl amine, triethyl amine, and trihexyl amine.

[0136] The amount of catalyst (C1) is preferably in the range from 0.1 to 5.0 wt.-%, more preferred 0.3 to 3.0 wt.-%, even more preferred 0.4 to 1 .5 wt.-% such as 0.5 to 1.0 wt.-% based on the solids content of the clearcoat composition of the invention.

[0137] Phosphoric acid catalysts (C2)

[0138] The phosphoric acid catalysts can be non-blocked or at least partially amine-blocked and are preferably selected from non-blocked or at least partially amine-blocked organophosphoric acids, such as from non-blocked or at least BASF Coatings GmbH Aug. 26, 2025 partially amine-blocked alkyl-phosphate esters, and non-blocked or at least partially amine-blocked aromaticphosphate esters, even more preferably it is selected from a non-blocked or at least partially amine-blocked monoester or diester of phosphoric acid, and most preferred a non-blocked or at least partially amine-blocked monoalkylester, dialkylester, monoarylester or diarylester of phosphoric acid or a mixture of two or more of the afore-mentioned esters, and particularly preferred a non-blocked or at least partially amine-blocked monophenyl phosphoric acid, a diphenyl phosphoric acid or a mixture thereof, also known as phenyl acid phosphate. The term "at least partially amine-blocked” also includes the meaning "fully amine-blocked.”

[0139] The amine with which the phosphoric acids are blocked are defined as the amines used for blocking the sulfonic acids (C1).

[0140] The amount of catalyst (02) is preferably in the range from 0.0 to 3.0 wt.-%, more preferred 0.2 to 2.0 wt.-%, even more preferred 0.4 to 1 .5 wt.-% such as 0.5 to 1 .0 wt.-% based on the solids content of the clearcoat composition of the invention.

[0141] Weight Ratio of amine-blocked sulfonic acids (C1) to amine-blocked phosphoric acids (C2)

[0142] The weight ratio of amine-blocked sulfonic acids (C1) to amine-blocked phosphoric acids (02), if (02) is present, is preferably from 0.8:1 to 10:1, more preferred from 1 :1 to 5:1, even more preferred 1.2:1 to 4:1.

[0143] The total amount of the catalyst (01) plus catalyst (02) based on the solids content of the clearcoat material of the present invention preferably ranges from 0.5 to 5.0 wt.-%, more preferred 0.8 to 4.0 wt.-%, even more preferred from 1 .0 to 3.0 wt.-% and most preferred from 1 .2 to 2.5 wt.-%.

[0144] Coatings Additives (D)

[0145] The clearcoat material according to the invention preferably contains coatings additives (D). Suitable coatings additives are for example light stabilizers, such as UV absorbers and reversible free-radical scavengers (HALS), antioxidants, degassing agents, wetting and dispersing agents, leveling agents, emulsifiers, slip additives, plasticizers, polymerization inhibitors, adhesion promoters, flow control agents, film-forming agents, rheological additives, such as thickeners and pseudoplastic sag control agents (SCAs), flame retardants, corrosion inhibitors, waxes, reactive diluents, driers, dyes and biocides. While catalysts belong to coatings additives, herein catalysts (C1) and (02) are discussed separately above and are, formally excluded from the calculation of the amounts of coatings additives (D). BASF Coatings GmbH Aug. 26, 2025

[0146] These and further suitable coatings additives (D) are described in the textbook “Lackadditive” by Johan Bieleman, Wiley-VCH, Weinheim, N.Y., 1998, in D. Stoye and W. Freitag (Editors), "Paints, Coatings and Solvents”, Second, Completely Revised Edition, Wiley-VCH, Weinheim, N.Y., 1998, "14.9. Solvent Groups”, pages 327 to 373.

[0147] Preferably, amongst the above additives, UV absorbers, light stabilizers and rheological additives are contained in the clearcoat materials of the present invention.

[0148] If light stabilizers are contained, they are contained, based on the solids content of the clearcoat material of the present invention, preferably in an amount in the range from 0.1 to 3.0 wt.%, more preferred in the range from 0.3 to 2.5 wt.-%, even more preferred in the range from 0.4 to 2.0 wt.-% and most preferred in the range from 0.5 to 1.5 wt.-%.

[0149] As rheological additives, preferably materials such as urea crystals and / or pyrogenic silica, preferably hydrophobic pyrogenic silica may be employed into the clearcoat material of the invention. The afore-mentioned rheological additives are preferably part of a rheological formulation comprising one or more solvents and one or more hydroxyfunctional polymers (A), preferably one or more hydroxy-functional poly(meth)acrylates (A1) and / or (A2), even more preferred one or more hydroxy-functional poly(meth)acrylates (A2).

[0150] It is further preferred that the clearcoat material of the invention contains leveling agents, preferably leveling agents comprising polysiloxane moieties.

[0151] While not completely excluded, it is possible that the clearcoat compositions may contain pigments and / or fillers in additive amounts. In such case it is preferred to use pigments and / or fillers which are transparent and have no or very low hiding power.

[0152] The total amount of the coating additives (D) based on the solids content of the clearcoat material of the present invention preferably ranges from 0.5 to 6.0 wt.-%, more preferred 0.8 to 5.0 wt.-%, even more preferred from 1 .0 to 4.0 wt.-% and most preferred from 1 .5 to 3.5 wt.-%.

[0153] Organic solvents (S)

[0154] The organic solvents as used in the clearcoat material of the invention may be non-polar or polar, aprotic or protic.

[0155] Non-polar, aprotic organic solvents, which are suitable for the clearcoat material of the invention are, e.g., aromatic or aliphatic hydrocarbons, such as Solvent Naphtha types. Polar aprotic solvents, which are suitable for the clearcoat material of the invention are, e.g., ester, ethers, glycol ethers, ketones etc., while suitable protic solvent are monoalcohols and glycols. BASF Coatings GmbH Aug. 26, 2025

[0156] It is preferred that the clearcoat material of the present invention contains monoalcohols such as ethanol and butanol, most preferred n-butanol.

[0157] Basecoat Material

[0158] The basecoat material used herein as part of the multilayer coating systems and the method of their production as described herein below can be selected from solvent-borne basecoat materials and water-borne basecoat materials. The solvent-borne basecoat materials can be one-pack coating materials or two-pack coating materials, preferably they are one-pack coating materials. The water-borne basecoat materials can also be one-pack coating materials or two-pack coating materials, preferably they are one-pack coating materials.

[0159] The basecoat materials used in the present inventio preferably contain one or more, preferably more than one hydroxy functional polymers, preferably selected from polyurethane resins, poly(meth)acrylate resins, and polyester resins. As crosslinking agent to crosslink with the hydroxy groups of the hydroxy functional polymers, particularly in one-pack basecoat materials, preferably aminoplast resins, more preferred melamine-formaldehyde resins and / or blocked polyisocyanates are employed. In the less preferred two-pack basecoat materials polyisocyanates with free isocyanate groups are employed.

[0160] Preferably, the basecoat material contains one or more organic or inorganic color pigments and / or effect pigments, such as platelet-shaped effect pigments, like metal effect pigments and pearlescent pigments.

[0161] Besides water and / or organic solvents, the basecoat materials preferably contain one or more coatings additives, such as those described under the above section “Coatings Additives (D)" for the clearcoat material of the present invention. Particularly preferred are wetting and dispersing additives to stabilize the pigments and / or fillers in the basecoat composition.

[0162] Multilayer Coating System

[0163] Multilayer coating system, comprising a basecoat layer and a clearcoat layer on said basecoat layer, the clearcoat layer being formed from a clearcoat material as defined in one of the preceding claims.

[0164] The multilayer coating systems are present on metallic or polymeric substrates. In case of metallic substrates, the clearcoat material of the invention is employed advantageously as part of a multilayer coating system at least comprising a basecoat layer and the clearcoat layer formed by application of the clearcoat material of the invention. Preferably, in case of metallic substrates, the substrate is pretreated and subsequently precoated with an electrocoat, one or more primer-surfacer coats, preferably one primer-surfacer coat, and one or more basecoats, before the clearcoat material of the invention is applied as the upper-most coating layer. BASF Coatings GmbH Aug. 26, 2025

[0165] In the case of polymeric substrates (i.e., plastics substrates) one or more of a primer surfacer, single-coat topcoat, basecoat, and clearcoat coating material can be applied prior the application of the clearcoat material of the invention as the upper-most coating layer. Typical polymeric substrates are PP / EPDM, polyamide and / or ABS, for example.

[0166] Metallic substrates are preferred. A metallic substrate can consist of a single metal or may be an alloy. Metals used as or as part of metallic substrates are, e.g., iron, aluminum, magnesium, or zinc. Typical alloys are, e.g., steel, such as cold-rolled steel, or galvanized steel, like hot-dip galvanized steel or electrogalvanized steel.

[0167] Method for Preparing a Multilayer Coating System

[0168] The invention further provides a method for preparing a multilayer coating system, characterized in that it at least comprises the following steps a. providing an uncoated or precoated substrate; b. applying at least one basecoat material on said substrate, thus forming a basecoat layer; and subsequently c. applying at least one clearcoat material of the invention on the only or the upper-most basecoat layer, thus forming at least one clearcoat layer; d. curing any not yet cured layer.

[0169] The uncoated or precoated substrate can be the same as described herein above for the multilayer coating system. It can be selected from metallic and polymeric substrates; metallic substrates being preferred.

[0170] Prior to the application of a first coating layer, it is preferred that the substrates are pretreated. The pretreatment of a polymeric substrate may be accomplished by thorough cleaning, plasma treatment or corona treatment, preferably followed by the application of an adhesion promoter.

[0171] The pretreatment of a metallic substrate may be accomplished by thorough cleaning and subsequently contacting with a pretreatment solution, e.g., in a phosphating step.

[0172] Particularly in case of metallic substrates the substrate is preferably precoated, first with an electrodeposition coat, such as an anodic or cathodic electrodeposition coat, preferably a cathodic electrodeposition coat, preferably followed by the application of a primer-surfacer coating material. While the electrodeposition coat is typically cured prior to the application of the primer-surfacer, the primer-surfacer, if present at all, might also be cured prior to the application of the one or more basecoat materials, but it is also possible to just dry the primer-surfacer, if present at all, prior to the application of the one or more basecoat materials. In the latter case, the basecoat material is applied "wet-on-wet” onto the primer-surfacer. BASF Coatings GmbH Aug. 26, 2025

[0173] The basecoat material may be employed in the same manner as described for the clearcoat material below. However, the basecoat material as used herein may be solvent-borne like the clearcoat material of the invention or water-borne (water-based), i.e. the main part, i.e. at least 50 wt.-%, more preferably at least 60 wt.-%, even more preferred at least 70 wt.-% or at least 90 wt.-% of the volatile content of the basecoat material is water. Thus, a thorough drying of the basecoat material subsequent to its application is preferred, when water-borne basecoat materials are employed. Thus, a flash-off as described for the clearcoat material herein below is preferred, even more preferred a flash-off at elevated temperature. Particularly preferred is a flash-off for 1 to 10 min, even better for 2 min to 8 min at a temperature in the range from 50 to 90 °C, even better at a temperature in the range of 70 to 80 °C. The presence of too much moisture in the basecoat layer prior to the application of the clearcoat material may result in a deteriorated appearance of the multilayer coating system. Moreover, any alkaline or basic compounds may migrate from the basecoat layer into the clearcoat layer of the invention and may thus interfere with the curing process of the clearcoat layer. As for the primer-surfacer, the basecoat layers can be cured prior to the application of the clearcoat material, or just dried. In the latter case the clearcoat material is applied wet-on-wet onto the basecoat layer.

[0174] Application of the clearcoat material of the invention to a substrate may be accomplished by all customary application methods, such as, for example, spraying, knife coating, spreading, pouring, dipping, impregnating, trickling, or rolling. In the course of such application, the substrate to be coated may itself be at rest, with the application unit or device being moved. Alternatively, the substrate to be coated, more particularly a coil, may also be moved, with the application unit being at rest relative to the substrate or being moved appropriately.

[0175] Preference is given to employing spray application methods. Such as, for example, compressed air spraying (pneumatic application systems), airless spraying, high-speed rotation, electrostatic spray application (ESTA), optionally in conjunction with hot spray application such as hot air spraying, for example.

[0176] The dry film thickness of the cured primer is preferably in the range from 6 pm and 35 pm, more preferred in the range from 8 pm to 30 pm and most preferred in the range from 10 pm to 25 pm.

[0177] The dry film thickness of the cured basecoat is preferably in the range from 8 pm and 25 pm, more preferred in the range from 10 pm to 22 pm and most preferred in the range from 12 pm to 20 pm.

[0178] The dry film thickness of the cured clearcoat is preferably in the range from 20 pm and 75 pm, more preferred in the range from 30 pm to 60 pm and most preferred in the range from 35 pm to 55 pm.

[0179] The dry film thickness of the cured multilayer coating system is preferably in the range from 34 pm and 135 pm, more preferred in the range from 48 pm to 112 pm and most preferred in the range from 57 pm to 100 pm. BASF Coatings GmbH Aug. 26, 2025

[0180] Following application and before curing of the clearcoat material of the invention, which forms the clearcoat layer, there may be a certain rest time or evaporation time (flash-off time). The rest time serves, for example, for leveling and for the devolatilization of the coating films, or for the evaporation of volatile constituents such as solvents. The rest time may be supported and / or shortened through the application of elevated temperatures and / or through a reduced atmospheric humidity, provided this does not entail any instances of damage to or alteration in the coating films, such as premature complete crosslinking, for instance.

[0181] Following application and, where practiced, the evaporation time of the clearcoat material of the invention on a substrate, curing takes place, to form a clearcoat. If the primer-surfacer layer or the basecoat layer or both have not yet cured, they are cured simultaneously with the clearcoat layer.

[0182] The thermal curing of the clearcoat coating composition of the invention has no peculiarities in terms of method, but instead takes place by the conventional methods such as heating, e.g., in a forced-air oven or irradiation with IR lamps. The thermal cure here may also take place in stages. Another method of curing is that of curing with near infrared (NIR radiation). Particularly advantageous is the thermal curing of the clearcoat coating composition of the invention. The thermal cure is in general at a temperature in the range of 80 to 200 °C, more preferably in the range of 100 to 190 °C, and even more preferably in the range of 120 to 180° C., during a time of 10 min up to 1 h, more preferred 12 min up to 30 min, and even more preferred in the range from 13 min up to 20 min.

[0183] Coated Substrate

[0184] The invention also provides a coated substrate, which is a metallic or polymeric substrate and comprises a multilayer coating system of the invention, wherein as upper-most coating layer a clearcoat layer formed from the clearcoat material of the invention was applied. The coated substrate is preferably cured, preferably under the same conditions as described for the method for preparing a multilayer coating herein above.

[0185] Use of the Clearcoat Material of the Invention

[0186] The invention further provides for the use of the clearcoat material of the invention for coating an uncoated or precoated substrate. Preferably the substrate is a vehicle body or part of a vehicle body, more preferably the substrate being an automotive vehicle body or a part of an automotive vehicle body. Most preferred is the use of the clearcoat material of the invention in automotive OEM coating and automotive repair coating.

[0187] In the following the invention will be further exemplified by inventive and comparative examples. BASF Coatings GmbH Aug. 26, 2025

[0188] EXPERIMENTAL SECTION

[0189] Any of the following methods (parameter determination and test methods) apply not only for to the experimental section, but are generally valid for the whole application.

[0190] Parameter Determination

[0191] G / ass Transition Temperature

[0192] The glass transition temperature (Tg) for the purposes of the invention for any hydroxyl functional polymer (A) is determined experimentally in a method based on DIN 51005 "Thermal Analysis (TA) Terms” and DIN 53765 "Thermal Analysis— Dynamic Scanning Calorimetry (DSC)'. With this method, a sample of 10 mg is weighed out into a sample boat and introduced into a DSC instrument. It is cooled to the starting temperature and then a 1stand 2ndmeasurement run is conducted with an inert gas flush (N2) of 50 ml / min and with a heating rate of 10 K / min, with cooling again to the starting temperature between the measurement runs. Measurement takes place typically in the temperature range from about 50° C lower than the anticipated glass transition temperature to about 50° C higher than the glass transition temperature. The glass transition temperature for the purposes of the present invention, based on DIN 53765, Section 8.1 , is the temperature in the 2ndmeasurement run at which half of the change in specific heat capacity (0.5 delta c) is attained. It is determined from the DSC diagram (plot of the heat flow against the temperature), and is the temperature of the point of intersection of the middle line between the extrapolated baselines before and after the glass transition with the measurement curve.

[0193] Hydroxy Value

[0194] The hydroxyl number (hydroxyl value) or OH number (OH value) for any of the hydroxy-functional polymers (A) indicates the amount of potassium hydroxide in milligrams that is equivalent to the molar amount of acetic acid bound on acetylation of one gram of the respective constituent. In the context of the present invention, unless indicated otherwise, the hydroxyl number for any hydroxyl functional polymer is determined experimentally by titration in accordance with DIN 53240-2 (Determination of hydroxyl value, Part 2: Method with catalyst).

[0195] Acid Value

[0196] The acid values were determined in accordance with DIN 53402. BASF Coatings GmbH Aug. 26, 2025

[0197] Weight-average Molecular Weight

[0198] The weight-average molecular weight Mwof all hydroxy-functional polymers (A) is determined by means of gel permeation chromatography at 40°C with a high-pressure liquid chromatography pump and a refractive index detector. The eluent used was tetrahydrofuran + 0.1 vol% acetic acid, with an elution rate of 1 ml / min. Calibration is carried out by means of polystyrene standards.

[0199] Theoretical Solids Content (= Non-Volatile Content = Solids Content)

[0200] The theoretical solids content (in wt.-%) (non-volatile content) was calculated by subtracting the amount(s) of any organic solvents from the total weight of the respective product in question, dividing the resulting weight by the total weight of the respective product itself, and multiplying the thus obtained result by 100. The difference to 100 wt.-% is the volatile content of the sample. The binder content (in wt.-%) (non-volatile content) was calculated by subtracting the amount(s) of any organic solvents, pigments, and fillers from the total weight of the respective product in question, dividing the resulting weight by the total weight of the respective product itself, and multiplying the thus obtained result by 100.

[0201] Viscosity

[0202] The theoretical solids content of the solvent-borne one-pack clearcoat material can also be measured after adjusting its viscosity to a flow time of 46 seconds using an AFNOR viscosity flow cup No. 4 at 23 °C (in accordance with French standard NF T 30-014). For the adjustment of the viscosity an organic solvent, as e.g. xylene can be used. The adjustment to such viscosity reflects the possibility to use the clearcoat materials in spray applications, since such spray applications typically require "spray viscosities.” To determine the theoretical solids content for a specific viscosity is to show that even after dilution to such typical viscosity a high-solids content is realized by the present invention.

[0203] Test Methods

[0204] Scratch Resistance - Crockmeter

[0205] Scratch resistance with and without reflow was tested with the Crockmeter test in accordance with the PSA Peugeot Citroen procedure D24 5010, initial and final gloss were determined. Curing conditions for the coated panel are shown in Table 4. 1

[0206] 230808W001 / S023829PCT

[0207] BASF Coatings GmbH Aug. 26, 2025

[0208] Scratch Resistance - Carwash

[0209] Scratch resistance was also tested with the Carwash test according to ISO 205666. Initial and final gloss were determined. Curing conditions for the coated panel are shown in Table 4.

[0210] Stone Chip Resistance

[0211] Stone chip resistance was tested in accordance with the PSA Peugeot Citroen procedure D24 1312. Curing conditions for the coated panel are shown in Table 4.

[0212] Multilayer Systems

[0213] Clearcoat Materials

[0214] The ingredients used in the inventive clearcoat material are listed in Table 1 and the amounts of the ingredients used are shown in Table 2.

[0215] Coating of Substrates

[0216] Steel panels were first pretreated with Gardobond R zinc phosphatation (commercially available from Chemetall GmbH) and afterwards coated with an electrodeposition coat (ED coat) (Cathogard 800, commercially available from BASF Coatings GmbH) in a dry film thickness of 17 to 25 pm.

[0217] For evaluation of the film performance, the electrodeposition coated panels were coated as described below using a pneumatic spray gun at a temperature of 25 °C and a relative humidity of 65 %. For determination of the coating's appearance, electrodeposition coated panels were coated as described below using an ESTA-automat at a temperature of 25 °C and a relative humidity of 65 %.

[0218] Application of OEM coating

[0219] A commcerically available solvent-borne basecoat (Colorclassic, BASF Coatings GmbH) such that the film thickness in the cured state was 12 ± 1.5 pm. Flash off was 7 min at room temperature.

[0220] The respective coating material described in Table 1 was adjusted to spray viscosity (AFNOR 4 cup; French standard NFT 30-070) of 46 s at 23 °C with addition of 1 wt.-% of xylene and afterwards applied wet-in-wet on top of the basecoat layer. After a flash-off for approximately 7 minutes coating materials were cured together with the BASF Coatings GmbH Aug. 26, 2025 basecoat. Exact curing conditions varied depending on the performed test and are defined in table 4. The dry film thickness of the clearcoat layer in the cured state was 37.5 ± 2.5 pm.

[0221] Application of a repair coating

[0222] If a repair coating was applied on the OEM coating, basecoat and clearcoat were applied again according to the procedure mentioned in the section “Application of OEM coating."

[0223] ASF Coatings GmbH Aug. 26, 2025 able 1 - Ingredients of the Clearcoat Materials

[0224] ASF Coatings GmbH Aug. 26, 2025 able 2 - Clearcoat Material (all amounts in parts by weight)

[0225] BASF Coatings GmbH Aug. 26, 2025

[0226] Table 3 - Ratios of Ingredients

[0227] Table 4 - Results BASF Coatings GmbH Aug. 26, 2025

[0228] In cross-cut adhesion testing the rating is from "a” to “e”. A rating of "a” is the best and “e” is the worst rating. The test is passed, if the rating is < b. In stone chip adhesion testing, ratings as from A to E (number of damages), A being best and E being worst; and 1 to 5 (size of the damages), 1 being best and 5 being worst. The test is passed, if the rating is < 3B. Scratch resistance testing is determined in gloss units from 0 to 100. The loss of gloss should be < 25 and < 15 (after reflow and adjustment to PMMA reference) to pass the test. In gradient oven testing temperature was raised from room temperature to 75 °C. A damage is acceptable, if it occurs at a temperature > 55 °C.

[0229] Thus, the results in Table 4 clearly show that the Example passed all test required by the automotive industry.

Claims

230808W001 / S023829PCTBASF Coatings GmbH Aug. 26, 2025CLAIMS1 . Solvent-borne one-pack clearcoat material, characterized in that it comprisesI. one or more hydroxy functional polymers (A), at least one of which is a poly(meth)acrylate (A1), possessing a. a glass transition temperature below -15 °C as determined by differential scanning calorimetry; b. a hydroxyl value in the range from 130 mg KOH / g to 300 mg KOH / g; and c. a weight-average molecular weight in the range 2000 g / mol to 9000 g / mol determined by gel permeation chromatography using a polystyrene standardII. two or more crosslinking agents (B), at least one of which is a melamine-formaldehyde resin possessing butoxymethyl groups and imino groups (B1); and at least one of which is a melamine-formaldehyde resin possessing methoxymethyl groups and imino groups (B2); and ill. a catalyst comprising one or more amine-blocked sulfonic acids (C1).

2. Solvent-borne one-pack clearcoat material according to claim 1 , characterized in that it contains as a further hydroxy-functional polymer (A), a polymer selected from poly(meth)acrylates (A2) differing from poly(meth)acrylates (A1) in that at least one of features a., b., or c. is not fulfilled, and polyesters (A3); and / or as a further crosslinking agent (B) a blocked polyisocyanates (B3).

3. Solvent-borne one-pack clearcoat material according to any of the preceding claims, characterized in that the poly(meth)acrylates (A1) comprises, in polymerized form, one or more alkyl (meth)acrylate monomers; one or more hydroxyalkyl (meth)acrylate monomers; and styrene.

4. Solvent-borne one-pack clearcoat material according to any of the preceding claims, characterized in that melamine-formaldehyde resin (B1) comprises as alkoxymethyl groups only butoxoxymethyl groups, preferably n-butoxymethyl groups and / or iso-butoxymethyl groups; and preferably comprises not more than 5 mole-% of methylol groups based on the sum of butoxymethyl groups and methylol groups; and230808W001 / S023829PCTBASF Coatings GmbH Aug. 26, 2025 melamine-formaldehyde resin (B2) comprises as alkoxymethyl groups only methoxymethyl groups; and preferably comprises not more than 5 mole-% of methylol groups based on the sum of methoxymethyl groups and methylol groups.

5. Solvent-borne one-pack clearcoat material according to any of the preceding claims, characterized in that the one or more amine-blocked sulfonic acid (C1) is selected from the group consisting of amine-blocked alkylbenzene sulfonic acids, preferably from amine-blocked p-toluene sulfonic acid and amine-blocked dodecylbenzene sulfonic acid.

6. Solvent-borne one-pack clearcoat material according to any of the preceding claims, characterized in that it further contains as a catalyst one or more phosphoric acid catalysts (C2) which are selected from the group consisting of non-blocked phosphoric acids catalysts and at least partially blocked phosphoric acid catalysts (02), and which are more preferably selected from the group of organophosphoric acids, most preferably from alkyl-phosphate esters and aromatic-phosphate esters, whereas these phosphoric acid catalysts (02) are even more preferably at least partially amine-blocked.

7. Solvent-borne one-pack clearcoat material according to any of the preceding claims, characterized in that it possesses a theoretical solids contentI. in the range from 40 to 70 wt.-%, more preferred from 45 to 65 wt.-% and most preferred from 50 to 70 wt.-%; and / orII. in the range from 35 to 65 wt.-%, more preferred from 40 to 60 wt.-% and most preferred from 45 to 65 wt.-%, if the viscosity of the solvent-borne one-pack clearcoat material is adjusted to a viscosity resulting in a flow time of 46 seconds using an AFNOR viscosity flow cup No. 4 at 23 °C.

8. Solvent-borne one-pack clearcoat material according to any of the preceding claims, characterized in that, based on the total solids content of the clearcoat material, the amount of poly(meth)acrylates (A1) is in the range from 30 to 60 wt.-%, more preferred in the range from 34 to 55 wt.-% and even more preferred in the range from 38 to 50 wt.-%, such as in the range from 40 to 45 wt.-%; and / or the amount of poly(meth)acrylates (A2) is in the range from 5 to 30 wt.-%, more preferred in the range from 7 to 25 wt.-% and even more preferred in the range from 10 to 22 wt.-%, such as in the range from 12 to 20 wt.-%; and / or the amount of polyesters (A3) is in the range from 2 to 20 wt.-%, more preferred in the range from 4 to 15 wt.-% and even more preferred in the range from 6 to 12 wt.-%, such as in the range from 7 to 10 wt.-%.230808W001 / S023829PCTBASF Coatings GmbH Aug. 26, 20259. Solvent-borne one-pack clearcoat material according to any of the preceding claims, characterized in that, based on the total solids content of the clearcoat material, the amount of crosslinking agent (B1) is in the range from 8 to 25 wt.-%, more preferred 10 to 20 wt.-%, even more preferred 12 to 18 wt.-%, and most preferred in the range from 14 to 16 wt.-%; and / or, preferably and, the amount of crosslinking agent (B2) is in the range from 8 to 25 wt.-%, more preferred 10 to 20 wt.-%, even more preferred 12 to 18 wt.-%, and most preferred in the range from 14 to 16 wt.-%.

10. Solvent-borne one-pack clearcoat material according to any of the preceding claims, characterized in that, based on the total solids content of the clearcoat material, the amount of amine-blocked sulfonic acids (C1) is in the range from 0.1 to 5.0 wt.-%, more preferred 0.3 to 3.0 wt.-%, even more preferred 0.4 to 1 .5 wt.-% such as 0.5 to 1.0 wt.-%; and the amount of non-blocked or at least partially amine-blocked phosphoric acid catalysts (C2) is in the range from 0.0 to 3.0 wt.-%, more preferred 0.2 to 2.0 wt.-%, even more preferred 0.4 to 1 .5 wt.-% such as 0.5 to 1 .0 wt.-%.11 . Solvent-borne one-pack clearcoat material according to any of the preceding claims, characterized in that the weight ratio of solids content of crosslinking agents (B1) to the solids content of the hydroxyfunctional polymers (A) is in the range from 7:93 to 34:66, more preferred in the range from 13:87 to 27:73, even more preferred in the range from 17:83 to 24:76; and / or the weight ratio of solids content of crosslinking agents (B2) to the solids content of the hydroxyfunctional polymers (A) is in the range from 7:93 to 34:66, more preferred in the range from 13:87 to 27:73, even more preferred in the range from 17:83 to 24:76.

12. Multilayer coating system, comprising a basecoat layer and a clearcoat layer on said basecoat layer, the clearcoat layer being formed from a clearcoat material as defined in one of the preceding claims.

13. Method for preparing a multilayer coating system, characterized in that it at least comprises the following steps providing an uncoated or precoated substrate; applying at least one basecoat material on said substrate, thus forming a basecoat layer; and subsequently applying at least one clearcoat material on the only or the upper-most basecoat layer, thus forming at least one clearcoat layer; curing any not yet cured layer,BASF Coatings GmbH Aug. 26, 2025 characterized in that the only or at least the upper-most clearcoat layer is formed from a solvent-borne one-pack clearcoat material as defined in claims 1 to 11 .

14. Coated substrate, characterized in that the substrate is a metallic or polymeric substrate and comprises a multilayer coating system as defined in claim 12 or as obtained according to claim 13.

15. Use of a solvent-borne one-pack clearcoat material as defined in any one or more of claims 1 to 11 for coating an uncoated or precoated substrate, preferably the substrate being a vehicle body or part of a vehicle body, more preferably the substrate being an automotive vehicle body or a part of an automotive vehicle body.

16. Use according to claim 15 wherein the solvent-borne one-pack clearcoat material is used in automotive OEM coating or automotive repair coating.

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