Tinted clearcoat compositions and methods for making such tinted clearcoat compositions

Abstract

The present invention relates to a tinted clear coat composition comprising at least one binder resin (A) having a functional group (i), at least one curing agent (B) having a functional group (ii) reactive with the functional group (i), and at least one pigment (C), wherein the tinted clear coat composition (TCC) is producible by the steps of: (a) providing a clear coat system (CS) comprising at least one binder resin (A) and at least one curing agent (B); (b) providing at least one component of a pigment premix (PP) comprising at least one pigment (C); (c) combining all or a part of the clear coat system (CS) with the at least one component of the pigment premix (PP); (d) grinding the mixture obtained in step (c); and (e) mixing, where applicable, the mixture obtained in step (d) with a missing portion of the tinted clear coat composition (TCC).

Description

[Technical field]

[0001] The present invention relates to a tinted clearcoat composition comprising at least one binder resin (A), at least one hardener (B) and at least one pigment (C), whereby the preparation of the tinted clearcoat composition comprises a specific grinding step, i.e. grinding a mixture comprising at least one component of a pigment premix (PP) and all or part of a clearcoat system. The present invention also relates to a method for the preparation of said tinted clearcoat composition, comprising a specific grinding step. The present invention also relates to a multi-layer coating comprising a layer (also called a film) produced by the tinted clearcoat composition, and to a method for the preparation of such a multi-layer coating. Finally, the present invention relates to the use of the tinted clearcoat composition for improving the color properties of a coating, in particular a multi-layer coating. [Background technology]

[0002] The color properties of coatings, especially multi-layer coatings, play a major role in various coating-related industrial fields, such as the automotive coating industry.As is known, traditionally, the color and / or effect of coatings are mainly influenced by basecoat compositions (i.e., coating compositions that contain a relatively large amount of pigments and therefore have high opacity, meaning that each basecoat coating layer ultimately determines the color of the entire coating).Clearcoat compositions and layers produced therefrom each traditionally have the main functions of weather resistance, mechanical stability (e.g., scratch resistance), as well as gloss properties, appearance and transparency (i.e., aesthetic properties that are not primarily related to such color).

[0003] However, as is known, efforts have been made in recent times to achieve specific color characteristics with the tinted clearcoat composition and each coating layer. This allows the tinted clearcoat to contain a specific amount of pigment, i.e. an amount that at the same time contributes to the overall color of the coating but does not achieve complete opacity, thus allowing visual recognition of the basecoat layer underneath. The overall characteristics, properties and functions of the clearcoat are of course maintained, but the tinting contributes very specific color characteristics to the overall coating, such as excellent chroma (saturation, color depth) and hue. By matching the color characteristics of the basecoat with those of the tinted clearcoat (or multiple tinted clearcoats), amazing color quality and variation can be achieved.

[0004] However, a fundamental concern in this regard is to achieve adequate transparency of the pigmented clear coat composition and the respective coating, i.e. a coating that exhibits very high transparency and low haze. The integration of the pigment into the underlying clear coat system is a major challenge. Without such good integration, a hazy, milky optical impression may result.

[0005] EP1406978B1 discloses a coating composition comprising a plurality of colorants in the form of a pigment paste, where the pigment paste contains pigments that are heavily ground and therefore have a very low particle size. The coating composition serves for a good color match with an already existing coating, for example within a repainting process. The coating composition therefore functions as a base coat composition. The low particle size of the pigments in the paste correlates with a low haze and therefore a high transparency of the pigment paste. These properties of the paste are also described as being responsible for the excellent properties of the final coating layer.

[0006] EP 2 883 919 A1 discloses pigmented (especially darkly pigmented) coating compositions that are infrared transparent and exhibit high color stability. Again, low haze (high transparency) of the paste correlates with advantageous properties of the resulting coating composition and final coating. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] EP1406978B1 [Patent Document 2] EP2883919A1 Summary of the Invention [Problem to be solved by the invention]

[0008] The objective underlying the present invention was to provide a tinted clearcoat composition that provides excellent color properties of the coating (i.e. multi-layer coating) such as high chroma (saturation, color depth) and hue. More specifically, the objective of the present invention was to contribute to the aforementioned properties by achieving excellent transparency and therefore low haze of the final tinted clearcoat layer and thus the multi-layer coating. [Means for solving the problem]

[0009] 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.

[0010] A first subject of the present invention is a tinted clear coat composition (TCC) comprising at least one binder resin (A) carrying a functional group (i), at least one hardener (B) carrying a functional group (ii) reactive with the functional group (i), and at least one pigment (C), whereby this tinted clear coat composition (TCC) can be prepared by the following steps: (a) providing a clearcoat system (CS) comprising at least one binder resin (A) and at least one hardener (B); (b) providing at least one pigment premix (PP) component comprising at least one pigment (C); (c) combining all or a portion of the clear coat system (CS) with at least one component of a pigment premix (PP); (d) grinding the mixture obtained in step (c); (e) mixing the mixture obtained in step (d) with missing parts of a tinted clear coat composition (TCC), if applicable;

[0011] A further subject of the present invention is a process for producing a method for the production of a medicament for the manufacture ... (1) providing a clearcoat system (CS) comprising at least one binder resin (A) and at least one hardener (B); (2) providing at least one pigment premix (PP) component comprising at least one pigment (C); (3) combining all or a portion of the clear coat system (CS) with at least one component of a pigment premix (PP); (4) grinding the mixture obtained in step (c); (5) mixing the mixture obtained in step (d) with a deficient portion of a tinted clear coat composition (TCC), if applicable; The present invention relates to a method for producing a tinted clear coat composition (TCC) comprising at least one binder resin (A), at least one curing agent (B) and at least one pigment (C).

[0012] The subject of the invention is also a multilayer coating comprising a layer prepared by the tinted clearcoat composition, and also a method for producing such a multilayer coating.Finally, the subject of the invention is the use of the tinted clearcoat composition for improving the color properties of a coating, in particular a multilayer coating.

[0013] As will be evident from the specification and examples section below, in the present invention, it has surprisingly been found that, contrary to what the prior art indicates, low haze (high transparency) of the pigment paste is not sufficient to predict and obtain excellent color properties of the final coating. Instead, although the haze of the pigment paste does have an effect, the overall picture and correlation also depends heavily on the compatibility of the pigment paste with the underlying clear coat material in which it is included to produce the tinted clear coat material. The present invention achieves reaching this compatibility by a specific method of producing the tinted clear coat composition, in particular a specific grinding process as outlined below. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Detailed Description of the Invention In the sense of the present invention, the term "comprising", for example in relation to the tinted clearcoat composition of the present invention, includes the meaning of "consisting of", but does not exclusively have the meaning of "consisting of". "Comprising" can also be referred to as "including only" or "including exclusively", i.e. "comprising" is referred to as a general term that includes the specific term "consisting of".

[0015] The term "a" also includes the meaning "at least one" unless expressly stated otherwise.

[0016] The percentages and amounts in wt.% (mass%) of each component present in the compositions given below add up to 100 mass% in each case based on the total mass of the respective composition, unless explicitly stated otherwise.

[0017] Tinted Clearcoat Compositions (TCC) of the Present Invention The coating composition of the present invention is a pigmented clearcoat composition.

[0018] As is known, a (non-pigmented) clear coat composition is a composition that is colorless and transparent and therefore does not contain any perceptible amount of pigment, preferably does not contain any pigment at all.Also as is known, in many industrial coating applications, such as the automotive coating industry, the clear coat layer is the top coating layer of a multi-layer coating, and therefore represents the layer that is in contact with the environment.Therefore, in addition to properties such as gloss, appearance, transparency, etc., the main functions and properties that must be met are weather resistance, mechanical stability, e.g. against scratches, and UV stability.

[0019] A tinted clearcoat composition remains a clearcoat composition with certain functions, properties and uses as outlined above, but is not completely colorless and transparent. Instead, it contains a certain amount of ingredients, especially pigments, that provide color. On the other hand, a tinted clearcoat composition does not provide a completely or almost completely opaque layer, and by this means is clearly distinguished from a typical tinted basecoat composition. Thus, tinted clearcoat compositions and coatings made therefrom are both transparent and tinted (also called translucent and tinted). Quite obviously, the degree and level of translucency and tinting properties are variable and depend in particular on the amount of coloring ingredients, especially pigments.

[0020] Clear Coat System The tinted clear coat compositions (TCC) of the present invention are based on (and therefore include) clear coat systems (CS), which in the context of the present invention are quite obviously recipes and respective formulations constituting clear coat compositions, i.e. compositions already used as clear coat compositions (whereby, as always, where appropriate and / or necessary, certain amounts of ingredients such as, for example, solvents for adjusting the application viscosity may of course be added at a later stage to complete).

[0021] However, the Clearcoat System (CS) (and the respective Clearcoat Composition) does not already contain the respective Pigment Premix (PP) components (defined below), i.e., the Pigment Premix (PP) components need to be combined with the Clearcoat System to produce the Tinted Clearcoat Composition (TCC).

[0022] The clear coat system (CS) comprises at least one binder resin (A) having a functional group (i) and at least one hardener (B) having a functional group (ii) reactive with the functional group (i). These components can be selected according to individual needs and requirements and can be selected from compounds known to be applicable in clear coat compositions. The same is true for the functional groups (i) and (ii).

[0023] The binder resin (A) can be selected from the group consisting of polyurethanes, polyureas, polyesters, polyamides, polyethers, poly(meth)acrylates and / or copolymers of structural units of said polymers. At least the binder resin (A) is particularly preferably selected from the group consisting of polyurethanes, polyesters, poly(meth)acrylates and / or copolymers of structural units of said polymers. The term "(meth)acrylic" or "(meth)acrylate" in the context of the present invention includes in each case the meanings "methacrylic" and / or "acrylic", or "methacrylate" and / or "acrylate".

[0024] At least one binder resin (A) has a functional group (i) that is reactive with a functional group (ii) of at least one curing agent (B) described below. Any common crosslinkable functional group known to those skilled in the art can be selected as the functional groups (i) and (ii). Preferably, the binder resin (A) has a functional group (i) selected from the group consisting of a primary amino group, a secondary amino group, a hydroxyl group, a thiol group, a carboxyl group and a carbamate group. Preferably, the at least one binder resin (A) has a hydroxyl group as the functional group (i).

[0025] Preferably, the at least one binder resin (A) has an OH number in the range of 15 to 400 mg KOH / g, more preferably 20 to 250 mg KOH / g.

[0026] The curing agent (B) may preferably be selected from aminoplast resins and / or blocked or free polyisocyanates. Among the aminoplast resins, melamine resins, such as melamine-formaldehyde resins, are preferred. Among the polyisocyanates, free polyisocyanates are particularly preferred. In this case, quite obviously, the clearcoat system (CS), and thus the tinted clearcoat composition (TCC), is preferably a two-component system / composition. In a particularly preferred embodiment, free polyisocyanates are selected as the curing agent (B), and the clearcoat system is a two-component system. However, this does not exclude that the clearcoat system comprises a further curing agent component, such as a melamine resin, which may be part of the main binder component of such a two-component system.

[0027] Thus, the functional group (ii) is preferably selected from blocked or free isocyanate groups and methylol groups.

[0028] The clear coat system (CS) and the tinted clear coat composition (TCC) of the present invention are preferably solvent-based. In the context of the present invention, a solvent-based coating system or composition preferably comprises a total amount of water of less than 10% by weight, preferably less than 5% by weight, more preferably less than 1% by weight, very preferably 0% by weight, in each case based on the total weight of the coating composition. The diluent (solvent) applied to the composition is therefore organic, i.e. an organic solvent. The at least one organic solvent is preferably present in a total amount of 10-70% by weight, more preferably 20-60% by weight, most preferably 30-50% by weight, in each case based on the total weight of the clear coat system (CS) / tinted clear coat composition (TCC).

[0029] Suitable solvents may be selected from aliphatic and / or aromatic hydrocarbons, such as toluene, xylene, solvent naphtha, Solvesso 100 or Hydrosol® (from APAL), ketones, such as acetone, methyl ethyl ketone or methyl amyl ketone, esters, such as ethyl acetate, butyl acetate, pentyl acetate or ethyl ethoxypropionate, ethers, or mixtures of the aforementioned solvents.

[0030] Further components which may be part of the clear coat system (CS) are customary and known coating additives in typical amounts, preferably from 0.01 to 20% by weight, more preferably from 0.1 to 10% by weight, in each case based on the total weight of the clear coat system (CS).

[0031] Examples of suitable coating additives include UV absorbers; light stabilizers, such as HALS compounds, benzotriazoles or oxalanilides; rheology modifiers, such as sag control agents (urea modified resins); organic and inorganic thickeners; free radical scavengers; slip additives; polymerization inhibitors; defoamers; wetting agents; dispersants; emulsifiers; fluorine compounds; adhesion promoters; curing catalysts, leveling agents; film forming aids, such as cellulose derivatives; fillers, such as nanoparticles based on silica, alumina or zirconium oxide; flame retardants; and mixtures thereof.

[0032] Preferably, the clearcoat system (CS), and therefore the tinted clearcoat composition of the invention, in each case comprises at least one rheology modifier selected from the group of urea-modified resins, in particular urea-modified poly(meth)acrylates.

[0033] As is known, typically, a coating composition comprising a binder and a hardener can be formulated as a one-component or two-component coating composition, which depends heavily on the choice of hardener (and the temperature at which the functional group (ii) starts to react with the functional group (i) of the binder (A)). The technical situation in this respect is common knowledge and does not require further explanation.

[0034] As is also known, in the case of two-component coating compositions, it is typical that the two components (also called main binder component (I) and hardener component (II)) are such that component (I) contains, besides the binder resin (resin component) and the solvent, all or at least the majority of all further components such as typical additives, and the hardener component in most cases contains only a small number or part of the additives such as the hardener, the solvent and the curing catalyst. Such a situation is quite obviously also applicable to the clear coat system (CS) and the tinted clear coat composition (TCC) of the present invention.

[0035] Preferably, the clearcoat system, and thus the tinted clearcoat composition (TCC) of the present invention, is formulated as a two-component coating system / composition: thus, a main binder component (I) comprising at least one binder (A) is provided, and a hardener component (II) comprising a hardener (B) is provided, whereby components (I) and (II) are prepared and stored separately from each other and then mixed prior to use, preferably immediately prior to application to a substrate.

[0036] The preparation of the clear coat system (CS) can be carried out by conventional means, i.e. by mixing the components of the clear coat system (CS) (or components (I) and (II) separately from each other in the case of a two-component composition) in standard mixing equipment. Of course, it is also conceivable, not only in the case of two-component clear coat systems (CS), to mix all the components at once in their entirety, but to mix only a portion of the components (all or only a portion of the total amount) and to reserve the remaining components / amounts for mixing and combining at a later stage. The reason for the explicit mention here is the step (c) outlined below, and the embodiment in which only a portion of the clear coat system (CS) is combined: "combining a portion of the clear coat system (CS) with the components of the pigment premix (PP)". In this embodiment, since only a portion of the clear coat system (CS) is combined with the components of the pigment premix (PP) and thus the remaining portion of the clear coat system is only added at a later stage (see step (e) below), it is similarly required that only the components and amounts that make up this portion of the clear coat system are mixed before the components of the pigment premix (PP) are added. However, since even in this scenario the clear coat system is fully defined (by (i) the part that is combined with the components of the pigment premix (PP) and (ii) the remaining part that is added in step (e)), this procedure also means that a clear coat system (CS) is provided in the sense of step (a) below.

[0037] The procedures described herein are within the meaning and scope of "Providing a Clearcoat System (CS)" according to step (a) below.

[0038] Pigment premix (PP) and components of pigment premix (PP) The tinted clearcoat composition (TCC) of the present invention comprises at least one pigment premix (PP) component.

[0039] The pigment premix very obviously comprises at least one pigment (C) as a first component, preferably exactly one pigment (i.e. one type of pigment). The pigment premix very obviously also comprises further components which respectively make it possible to provide a mixture in which the pigment is properly dispersed and integrated. The types of the respective components are outlined below.

[0040] Suitable pigments are, for example, organic and inorganic color pigments, effect pigments and mixtures thereof. Such color pigments and effect pigments are known to those skilled in the art and are described, for example, in Roempp-Lexikon Lacke und Druckfarben, Georg Thieme Verlag, Stuttgart, New York, 1998, pages 176 and 451. The terms "color pigment" and "colorant" are interchangeable, as are the terms "visual effect pigment" and "effect pigment". Suitable inorganic colour pigments are selected from (i) white pigments such as titanium dioxide, zinc white, coloured zinc oxide, zinc sulphide, lithopone; (ii) black pigments such as iron oxide black, iron manganese black, spinel black, carbon black; (iii) colourants such as ultramarine green, ultramarine blue, manganese blue, ultramarine violet, manganese violet, iron oxide red, molybdate red, ultramarine red, iron oxide brown, mixed brown, spinel and corundum phases, iron oxide yellow, bismuth vanadate; (iv) filler pigments such as silicon dioxide, quartz flour, aluminium oxide, aluminium hydroxide, natural mica, natural and precipitated chalk, barium sulphate, and (vi) mixtures thereof.

[0041] Suitable organic colored pigments are: (i) monoazo pigments, such as CI Pigment Brown 25, CI Pigment Orange 5, 36 and 67, CI Pigment Orange 5, 36 and 67, CI Pigment Red 3, 48:2, 48:3, 48:4, 52:2, 63, 112 and 170, and CI Pigment Yellow 3, 74, 151 and 183; (ii) diazo pigments, such as CI Pigment Red 144, 166, 214 and 242, CI Pigment Red 144, 166, 214 and 242, and CI Pigment Yellow 83; (iii) anthraquinone pigments, such as CI Pigment Yellow 147 and 177, and CI Pigment Violet 31; (iv) benzimidazole pigments, such as CI Pigment Orange 64; (v) quinacridone pigments, such as CI Pigment Orange. (vi) quinophthalone pigments, such as CI Pigment Yellow 138; (vii) diketopyrrolopyrrole pigments, such as CI Pigment Orange 71 and 73, and CI Pigment Red 254, 255, 264 and 270; (viii) dioxazine pigments, such as CI Pigment Violet 23 and 37; (ix) indanthrone pigments, such as CI Pigment Blue 60; (x) isoindoline pigments, such as CI Pigment Yellow 139 and 185; (xi) isoindolinone pigments, such as CI Pigment Orange 61, and CI Pigment Yellow 109 and 110; (xii) metal complex pigments, such as CI Pigment Yellow 153; (xiii) perinone pigments, such as CI Pigment Orange. 43; (xiv) perylene pigments, such as CI Pigment Black 32, CI Pigment Red 149, 178 and 179, and CI Pigment Violet 29; (xv) phthalocyanine pigments, such as CI(xvi) aniline black, e.g. CI Pigment Black 1; (xvii) azomethine pigments; and (xviii) mixtures thereof.

[0042] Suitable effect pigments are selected from the group consisting of: (i) platelet-shaped metallic effect pigments, such as platelet-shaped aluminum pigments, gold bronzes, fire color bronzes, iron oxide-aluminum pigments; (ii) pearlescent pigments, such as metal oxide mica pigments; (iii) platelet-shaped graphite pigments; (iv) platelet-shaped iron oxide pigments; (v) multilayer effect pigments from PVD films; (vi) liquid crystal polymer pigments; and (vii) mixtures thereof.

[0043] Preferred pigments (C) of the pigment premix (PP) are organic pigments (i.e. organic colored pigments).

[0044] The pigment premix (PP) also preferably contains a solvent, in particular an organic solvent.Suitable solvents are described above in the context of the clear coat system (CS) and are also incorporated herein by reference with respect to the pigment premix (PP).Therefore, the pigment premix (PP) is preferably solvent-based.

[0045] Furthermore, the pigment premix preferably contains additive components generally known to stabilize the pigment (C) in the solvent. Such additive components can be selected from dispersants, wetting agents and / or emulsifiers. Such additive compounds can be selected according to individual needs and requirements and are known to those skilled in the art. The same applies to the amounts of these additive components.

[0046] A preferred group of additives are polymeric dispersants, such as those produced by controlled free radical polymerization (CFRP). As is known, this method defines the polymer structure and allows for particularly low polydispersity. A representative example of such a polymeric dispersant is EFKA PX 4350 (BASF SE).

[0047] Furthermore, even if not always necessary and / or required, a binder resin component may be present in the pigment premix (PP). As is known, such a component may also promote the stabilization of the pigment. The preferred resin component is a polyester, preferably used in the form of a dispersion or solution of the polyester in an organic solvent.

[0048] Above, the pigment premix (PP) and the respective components contained therein are described. However, it is important to note that according to the present invention and the essential step (c) (which will be described in more detail below), all or part of the clear coat system (CS) is combined with at least one component of the pigment premix (PP). Such a pigment premix is ​​thus defined by its components, but these components do not necessarily have to be mixed and / or ground before being combined with all or part of the clear coat system (CS). In other words, the pigment premix does not necessarily have to be produced separately before being combined with all or part of the clear coat system (CS). Instead, any further conceivable procedure of combining the components of the pigment premix (PP) with all or part of the clear coat system (CS) can be carried out. In fact, it is preferred not to produce the pigment premix (PP) (i.e. to mix / disperse and, if appropriate, grind the components of the pigment premix (PP)) before combining with all or part of the clear coat system (CS). For example, it is possible to combine any and all of the constituents of the pigment premix (PP) with all or a portion of the clearcoat system (CS) in one mixing operation within step (c). Within such a single mixing operation, for example, the order of addition of the components of the pigment premix and all or a portion of the clearcoat system can, of course, be varied.

[0049] The term "single mixing operation" (sometimes also called "single mixing and / or dispersing operation" or "single dispersing operation") quite obviously means that the (individual) components of the pigment premix (PP) and all or part of the clear coat system (CS) (as one further individual component) are brought together in one mixing and / or dispersing operation, i.e. the components are not premixed in a separate mixing procedure, whereas the further components are added to the thus pre-prepared premix at a later stage, in a further separate mixing operation. Thus, in this scenario it is excluded that for example the pigment premix is ​​pre-manufactured before combining it with all or part of the clear coat system (CS).

[0050] However, as already explained above, "one mixing operation" does not, of course, mean that all ingredients must necessarily be combined at once, and there may be a particular order of addition of the individual ingredients within the one mixing operation.

[0051] The term "ingredients" in the context of "ingredients of a pigment premix (PP)" quite obviously does not define only the type of ingredients. Instead, since the respective amounts of the individual ingredients are also essential to define a mixture such as a pigment premix (PP), the term "ingredients of a pigment premix" includes both the types and respective amounts of ingredients that make up the final pigment premix (i.e. the recipe). In other words: the term "ingredients of a pigment premix" is equivalent to "the types and amounts of ingredients that make up this pigment premix".

[0052] Preferably, the components of the pigment premix comprise pigment (C), an organic solvent, and additives that promote the stabilization of pigment (C) in the organic solvent, i.e. additives selected from dispersants, wetting agents and / or emulsifiers.

[0053] The tinted clear coat composition of the present invention preferably comprises at least one pigment (C) in a total amount of 0.05 to 10% by weight, preferably 0.1 to 4% by weight, very preferably 0.1 to 1.0% by weight, based on the total weight of the tinted clear coat composition.

[0054] Further ingredients: As already mentioned above, the essential components of the tinted clear coat composition (TCC) of the present invention are contained in the clear coat system (CS) and the pigment premix. Also, as already mentioned above, in particular due to the clear coat system (CS), the tinted clear coat composition of the present invention already contains all the components necessary for a functioning clear coat composition (i.e. a composition suitable as a clear coat composition). Nevertheless, as also already mentioned above, the possibility is not excluded that the final tinted clear coat composition may contain a certain amount of components for the final completion, such as, for example, a solvent for adjusting the application viscosity.

[0055] Preparation of the clear coat composition (TCC) of the present invention: The essential and novel properties of the clearcoat composition of the present invention are realized by certain process characteristics during manufacture. These process characteristics therefore result in these novel properties of the composition of the present invention (TCC) and therefore in the advantageous technical properties. Moreover, at present, no other way of defining these novel properties is known, except for the specific process characteristics described below.

[0056] Steps (a) and (b) of the process by which a tinted clearcoat composition can be produced are (a) providing a clearcoat system (CS), and (b) providing at least one component of a pigment premix (PP). The components of the clearcoat system (CS) and the pigment premix are outlined above.

[0057] In step (c) of the process, all or a portion of the clearcoat system (CS) is combined with at least one component of a pigment premix (PP).

[0058] As mentioned above, all or part of the clearcoat system (CS) is combined with a pigment premix (PP).

[0059] As is evident from the above description of the pigment premix (PP) and its components, step (c) can be carried out by conventional means, i.e., by mixing and / or dispersing the respective components (i.e., the components of the pigment premix and all or part of the clearcoat system (CS)) in standard mixing equipment.

[0060] Preferably, combining all or part of the clearcoat system (CS) with at least one component of the pigment premix (PP) in step (c) is carried out in one mixing and / or dispersing operation.

[0061] Thus, preferably, the (individual) components of the pigment premix (PP) and all or part of the clear coat system (CS) (as one further component) are brought together in one mixing and / or dispersing operation within step (c). However, this preferred embodiment does not exclude carrying out any further steps of mixing / dispersing (i.e. further mixing and / or dispersing operations) within step (c). For example, the mixture obtained after the first mixing operation comprising combining all or part of the components of the pigment premix (PP) and the clear coat system (CS) can be transferred to a further mixing / dispersing device, for example in order to obtain a more finely dispersed mixture as a basis for the grinding step (d).

[0062] The mixing can be carried out by conventional mixing and / or dispersing equipment, such as, for example, dissolvers. The mixing / dispersing can also be carried out via specific dispersing equipment, i.e. powder wetting equipment, such as in-line dispersers with rotor-stator systems. As is known, these highly efficient dispersing units can provide a finely dispersed mixture optimally prepared for the subsequent grinding step.

[0063] As already mentioned above, in the first alternative embodiment, "part" can mean that only a part of the components of the clearcoat system (CS) are combined with the components of the pigment premix (PP). Thereby, from a part of the combined clearcoat system (CS) components, their entire amount or only a part of their entire amount may be applied. It is also quite obviously conceivable to apply the entire amount of one or more components, while applying only a part of the total amount of one or more other components. By "total amount" is meant the entire amount intended to be applied in the clearcoat system (CS). In the case of, for example, a two-component clearcoat system, a scenario encompassed in this first alternative embodiment is that part or the entire main binder component (I) (i.e. part or the entire main binder component (I) previously prepared) is combined with the pigment premix (PP) in step (c) and the hardener component (II) is added only at a later stage, i.e. in step (e) (defined below).

[0064] In the second alternative embodiment, "partial" means that all components of the clear coat system (CS) are combined with components of the pigment premix (PP), but at least one component of the clear coat system (CS) is not applied in its entirety. For example, in the case of a one-component clear coat system (CS), this alternative embodiment is fulfilled by using only a portion of the (already finally manufactured) clear coat system (CS) in step (c). Thereby, all components are applied, and furthermore, all these components are not applied in their entirety in step (c).

[0065] The part of the clearcoat system (CS) which is combined with the components of the pigment premix preferably contains in each case at least one binder resin (A).

[0066] As outlined above, the clear coat system (CS), and thus the tinted clear coat composition (TCC), is preferably a two-component coating system / composition. Even more preferably, in this embodiment, only a portion of the clear coat system (CS) is combined with a component of the pigment premix (PP). More preferably, the portion of the clear coat system (CS) that is combined with a component of the pigment premix (PP) is all or a portion of the main binder component (I). Most preferably in this respect, the portion of the clear coat system (CS) that is combined with a component of the pigment premix (PP) is a portion of the main binder component (I).

[0067] In the context of the above-mentioned preferred embodiments, i.e. when all or part of the main binder component (I) is combined with a component of a pigment premix (PP), it is preferred that the weight ratio of all or part of the main binder component (I) to the at least one component of the pigment premix (PP) is 10:90 to 99:1, more preferably 15:85 to 98:5, even more preferably 20:80 to 97:3.

[0068] The amount of the pigment in the mixture obtained in step (c) is preferably 0.1 to 10 mass %, more preferably 0.2 to 7.5 mass %, based on the total amount of the mixture obtained in step (c).

[0069] Step (d) of the method is the grinding of the mixture obtained in step (c). This step can be called crucial for the present invention. It means in particular that at least a part of the clear coat system (CS), i.e. at least a part of the respective formulations constituting the clear coat composition, i.e. the composition already used as the clear coat composition, and the components of the pigment premix (PP) are ground after being combined. In other words, this step is quite obviously different from simply grinding the components of a standard pigment paste and / or pigment premix, but means that the components of the pigment premix (PP) are ground with at least a part of the clear coat system (CS) and therefore with at least a part of the final pigmented clear coat composition (TCC).

[0070] As is known, milling means contacting the respective components under high shear sufficient to result in a pigment dispersion, i.e. wetting the surface of the pigment particles. The milling process also involves the use of grinding media, i.e. grinding beads, such as glass beads. The shear introduced by this milling process is thereby also responsible for breaking down the pigment agglomerates into smaller particle sizes and ultimately into primary pigment particles, preferably as already outlined above.

[0071] The respective grinding equipment, such as high-energy mills, and the respective procedures are well known and can be selected depending on the individual case. It has proven advantageous that the preferably applied grinding beads, which are well known, generally have a particle size of, for example, about 0.05-10 mm, preferably 0.05-2.5 mm or 0.05-1 mm (diameter), whereby the grinding is carried out for a duration of, for example, 1-20 hours. Under these conditions, commercially available grinding equipment can provide an energy input (specific energy) of, for example, 50-10000 Wh / kg, preferably 100-5000 Wh / kg. The grinding process can also be carried out in different grinding steps, which differ, for example, in terms of bead size, mass ratio of mixture to beads and / or grinding time (and therefore also energy input). After grinding, the prepared dispersion is separated from the grinding beads, in particular by filtration.

[0072] The grinding step (d) and the resulting mixture achieves compatibility of the components of the pigment premix (PP), especially the pigment (C), with the underlying clear coat material (i.e., the clear coat system (CS)), ultimately resulting in excellent color properties of the final clear coat layer and multi-layer coating, respectively.

[0073] Preferred embodiments, in particular the preferred combination of steps (c) and (d), are described below.

[0074] In a first preferred embodiment, combining all or part of the clear coat system (CS) with at least one component of the pigment premix (PP) is carried out in step (c) in one mixing and / or dispersing operation. Even more preferably, step (c) is carried out in exactly one mixing and / or dispersing operation (i.e., step (c) comprises only one mixing and / or dispersing operation). The mixing / dispersing can be carried out by conventional means, for example via a dissolver.

[0075] The grinding step (d) is in this first preferred embodiment carried out by at least two different sub-steps, more preferably exactly two sub-steps, whereby the first sub-step is carried out with an energy input of 50-1000 Wh / kg, preferably 100-500 Wh / kg, and the second sub-step is carried out with an energy input of more than 1000-5000 Wh / kg, preferably 1500-3500 Wh / kg. Suitable, and therefore preferred, grinding beads have a particle size (diameter) of 0.5-5 mm (first sub-step) and 0.05-0.25 mm (second sub-step).

[0076] In a second preferred embodiment, step (c) involves the use of a powder wetting device, such as an in-line disperser equipped with a rotor-stator system.

[0077] Thereby, step (c) can be carried out in exactly one dispersing operation through an in-line disperser with a rotor-stator system (option (c1)), or preferably, step (c) is carried out in at least two (preferably exactly two) dispersing operations, whereby in-line dispersers with rotor-stator systems are applied in both operations (option (c2)).Thereby, the in-line disperser applied in the second step has a finer rotor-stator shape than the in-line disperser applied in the first step.

[0078] Quite obviously, within option (c1), the combination of all or part of the clear coat system (CS) with at least one component of the pigment premix (PP) is carried out in one dispersion operation (as there is only one such dispersion operation).

[0079] Also, for option (c2), it is preferred to combine all or part of the clear coat system (CS) with at least one component of the pigment premix (PP) in one dispersing operation, i.e. in the first dispersing operation. Thus, the components of the pigment premix (PP) and all or part of the clear coat system (CS) (as one further component) are combined in this first dispersing operation, while the mixture thus obtained after this first operation is then transferred to a further in-line disperser for further dispersing operations, thereby obtaining a more finely dispersed mixture that is the basis for the grinding step (d).

[0080] Step (d) according to this second preferred embodiment is carried out in exactly one step, i.e. only one grinding step is applied, whereby the grinding step is carried out with an energy input of more than 1000 to 5000 Wh / kg, preferably 1500 to 3500 Wh / kg. Suitable, and therefore preferred, grinding beads have a particle size (diameter) of 0.05 to 0.25 mm.

[0081] As outlined above with respect to step (c) and also evident from the first and second preferred embodiments described previously, it is preferred not to prepare the pigment premix (PP) (i.e. by mixing and, where appropriate, grinding the components of the pigment premix (PP)) before combining it with all or part of the clear coat system (CS), but to combine the individual components of the pigment premix as they are (and not already in their final mixed and ground form) with all or part of the clear coat system (CS) in one mixing operation. Surprisingly, it has been found that this procedure and its combination with the respective above-mentioned preferred grinding step (d) (described in the first and second preferred embodiments) results in significant energy savings, since the pre-production of the pigment premix also usually involves a grinding step with high energy input, whereas the subsequent combination with all or part of the clear coat system (CS) and subsequent grinding in step (d) again requires high energy input, whereas the preferred procedure discussed here finally requires, overall, significantly less energy input, as further shown in the examples.

[0082] The total energy input during grinding in the production of the inventive tinted clear coat composition (TCC) is preferably less than 4000 Wh / kg, more preferably less than 3500 Wh / kg, and most preferably less than 3000 Wh / kg.

[0083] Surprisingly, it has also been found that the haze of the mixture obtained after step (d) does not necessarily correlate to, and thus is exclusively responsible for, the improved color properties of the final clear coat layer and multi-layer coating, although the haze may be selected to be equal to or less than 25%, preferably equal to or less than 20%, more preferably equal to or less than 5%.

[0084] The term "haze" is known to those skilled in the art. Haze is a measurement of transparency as defined by ASTM D 1003. The method for measuring the haze of the pigment pastes used in the present invention (and comparatively used) is described in the "Method" section below.

[0085] After grinding in step (d), in a further step (e), the missing parts of the tinted clear coat composition (TCC) are mixed with the mixture obtained after step (d). These missing parts are quite obviously the remaining parts of the clear coat system (CS) (if only a part of the clear coat system (CS) is applied in step (c)). However, in general, further components, such as solvents or other components added for completion, are also conceivable.

[0086] After completion of step (e), a tinted clearcoat composition of the present invention is provided.

[0087] Preferably, the total solids content of the tinted clear coat composition (TCC) 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 tinted clear coat composition.

[0088] Method for Producing the Tinted Clearcoat Composition (TCC) of the Present Invention The present invention also relates to a method for producing a tinted clear coat composition (TCC). The essential steps of the production of the tinted clear coat composition are fully described and defined above. Also, all the preferred features and embodiments outlined above apply to the method for producing the tinted clear coat composition (TCC). The same applies to any and all aspects of such a tinted clear coat composition (TCC), in particular the preferred components of the composition.

[0089] Multi-layer coating and method for producing such a multi-layer coating - Patents.com The present invention also relates to a multi-layer coating comprising a layer prepared by the tinted clear coat composition, and to a method for producing such a multi-layer coating. Here again, in the context of the multi-layer coating and the method for producing such a multi-layer coating, both the essential features and also any preferred embodiments relating to the clear coat composition (TCC) of the present invention apply analogously.

[0090] The method for producing the multi-layer coating of the present invention comprises the following steps: (1) providing an optionally precoated substrate; (2) applying a pigmented basecoat composition to the optionally precoated substrate according to step (1), thereby producing a first basecoat film; (3) optionally applying at least one additional pigmented basecoat composition different from the basecoat composition applied in step (2) to the first basecoat film present on the substrate after step (1), thereby producing at least one additional basecoat film on the first basecoat film; (4) applying a tinted clearcoat composition to the top basecoat film produced in step (2) and optional step (3), thereby producing a tinted clearcoat film on said top basecoat film; Including, Here, the tinted clearcoat composition applied in step (4) is a tinted clearcoat composition (TCC) of the present invention.

[0091] Preferably, all the above steps are carried out by spray application.

[0092] The above-mentioned coating films formed on the optionally precoated substrate by carrying out steps (2) to (4) are preferably uncured coating films at this stage. Therefore, the coating compositions applied in each of these steps are preferably applied wet-on-wet. In this case, curing is carried out thereafter, that is, all coating films are cured jointly after their production.

[0093] Also, preferably, the above-mentioned coating films are adjacent to each other, i.e. directly overlap each other, without any additional coating film / layer in between.More particularly, this means that at least one additional base coat film produced in step (3) is adjacent to the first base coat film produced in step (2), and the tinted clear coat film produced in step (4) is adjacent to the top base coat film produced in step (2) and any step (3).

[0094] The method of the present invention is particularly suitable for coating automotive bodies or parts thereof, including not only respective metal substrates but also plastic substrates, such as polymeric substrates. Thus, the preferred substrate is an automotive body or part thereof.

[0095] Suitable metal substrates used according to the present invention are all substrates that are commonly used and known to those skilled in the art.The substrates used according to the present invention are preferably metal substrates, more preferably selected from the group consisting of steel, preferably bare steel, cold rolled steel (CRS), hot rolled steel, galvanized steel such as hot dip galvanized steel (HDG), alloy galvanized steel (such as galvalume, galvanal or galfan) and aluminized steel, aluminum and magnesium, and also selected from the group consisting of Zn / Mg alloy and Zn / Ni alloy.A particularly suitable substrate is a part of an automobile body or a complete body for automobile production.

[0096] Preferably, thermoplastic polymers are used as plastic substrate.Suitable polymers include poly(meth)acrylates, such as polymethyl(meth)acrylate, polybutyl(meth)acrylate, polyethylene terephthalate, polybutylene terephthalate, polyvinylidene fluoride, polyvinyl chloride, polyesters, such as polycarbonate and polyvinyl acetate, polyamides, polyolefins, such as polyethylene, polypropylene, polystyrene, and also polybutadiene, polyacrylonitrile, polyacetal, polyacrylonitrile-ethylene-propylene-diene-styrene copolymer (A-EPDM), ASA (acrylonitrile-styrene-acrylic acid ester copolymer) and ABS (acrylonitrile-butadiene-styrene copolymer), polyetherimide, phenolic resins, urea resins, melamine resins, alkyd resins, epoxy resins, polyurethanes including TPU, polyetherketones, polyphenylene sulfides, polyethers, polyvinyl alcohols, and mixtures thereof. Polycarbonates and poly(meth)acrylates are particularly preferred.

[0097] The substrates used according to the invention are preferably metal substrates pretreated with at least one metal phosphate, such as zinc phosphate, and / or with at least one oxalate. This type of pretreatment by phosphating is usually carried out after the substrate has been cleaned and before the substrate is electrocoated, and is a pretreatment step which is particularly common in the automotive industry.

[0098] As outlined above, the substrate used may be a precoated substrate, i.e. a substrate having at least one cured coating film. The substrate provided in step (1) may be precoated with a cured electrodeposition coating layer. The substrate may additionally or alternatively be provided with 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 the substrate with a cured electrodeposition coating layer. If a cured primer coating film is also present, the cured electrodeposition coating film is present below, preferably adjacent to, the cured primer coating film. This curing of the primer may be carried out at a temperature in the range of 40 to 140°C, and may in particular include a "low temperature bake" step at a temperature in the range of 80 to 100°C. As outlined above, substrates provided with an uncured primer coating film may be used, in particular substrates such as metal substrates with a cured electrodeposition coating film, on which said uncured primer coating film is present. Thus, the method of the present invention may comprise an additional step carried out before step (1), according to which a primer composition is provided to an optionally precoated substrate to form a primer coating film on the optionally precoated substrate. The primer may be cured separately or may only be flashed off, such as at a temperature preferably not exceeding 40° C., for example in the range of 18-30° C., with a flash-off time of 1-20 minutes, meaning that the curing of the primer takes place at a later stage.

[0099] The basecoat compositions applied in step (2) and optional step (3) are each preferably aqueous, i.e., water-borne, coating compositions. However, the basecoat compositions applied in step (2) and optional step (3) may alternatively be solvent-based basecoat compositions. Preferably, the basecoat compositions applied in step (2) and optional step (3) are one-component or two-component compositions, more preferably one-component compositions.

[0100] The term "solvent-based" has already been explained above. The term "aqueous" or "water-borne" is preferably understood for the purposes of the present invention to mean that water is present as the main component of all solvents and / or diluents present in the respective composition, preferably in an amount of at least 35% by weight, based on the total weight of the respective composition. More preferably, the compositions comprise a water content of at least 40% by weight, more preferably at least 45% by weight, very preferably at least 50% by weight, in each case based on the total weight of the respective composition. The proportion of organic solvent(s) is preferably less than 20% by weight, more preferably in the range from 0 to less than 20% by weight, very preferably in the range from 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 respective composition.

[0101] As pigmented basecoat composition applied according to step (2) and, optionally, step (3), compositions conventionally known for these purposes can be selected.

[0102] As mentioned above, it is preferred that all coating films produced in steps (2)-(4) are cured together, meaning that after application of the basecoat composition, each film is flashed off, e.g., for 1-20 minutes, more preferably 2-15 minutes, before a further composition is applied. Preferably, the flash-off is carried out at a temperature not exceeding 40°C, more preferably at a temperature in the range of 18-30°C.

[0103] The term "flash-off" in the sense of the present invention preferably means drying, where at least a portion and / or a part of the amount of solvent (water and / or organic solvent(s)) is evaporated from the coating film before the next coating composition is applied and / or curing takes place. No curing takes place by flash-off.

[0104] In step (4), the tinted clear coat composition (TCC) of the present invention is applied. Preferably, after application of the composition (TCC), no further coating composition is applied, which means that the film and layer formed by the composition (TCC) respectively is the top layer of the multi-layer coating produced.

[0105] As already mentioned above, step (4) is preferably carried out before the curing of the at least one basecoat film according to step (2) and optionally step (3) is carried out.

[0106] After the composition (TCC) has been applied in step (4) to produce the tinted clearcoat film, the film can be flashed off essentially as described above.

[0107] The method of the present invention preferably comprises as a further step (5) a co-curing of the films applied in steps (2) to (4), thereby obtaining a cured multi-layer coating.

[0108] Preferably, step (5) is carried out at a temperature below 150° C., preferably below 130° C., in particular in the range of 15 to 110° C. or 15 to 90° C., for 5 to 45 minutes, preferably 20 to 45 minutes, in particular 25 to 35 minutes.

[0109] Methods of Using the Tinted Clearcoat Compositions (TCC) of the Present Invention Finally, the present invention relates to a method of using the tinted clearcoat composition (TCC) to improve the color properties of coatings, particularly multi-layer coatings.

[0110] method 1. Determination of Nonvolatile Fraction The non-volatile content (solid or solids content) is determined according to DIN EN ISO 3251 (date: June 2019). This involves weighing 1 g of sample into a previously dried aluminum dish and drying the dish with the sample at 180 °C for 30 min in a drying cabinet, then cooling in the oven and weighing again. The residue relative to the total amount of sample used corresponds to the non-volatile content (unit: % or mass %).

[0111] 2. Hayes The mixture, e.g., pigment premix or pigment paste to be subjected to haze measurement, is diluted with deionized water (for aqueous pigment pastes) or n-butyl acetate (for solvent-based pigment pastes) to provide a suitable diluted sample to be used for the measurement. The measurement is performed within 24 hours of preparing the sample to be measured. The device used to measure haze is a Haze Guard Plus device available from Byk-Gardner. The device is calibrated with a solution-based quartz cuvette flow sample holder with deionized water or n-butyl acetate as reference standard. A 500 micron path length cell is used for the measurement. The measurement is performed at the wavelength of maximum absorbance with a transmission of 17.5% ± 1.0% (the transmission is adjusted by dilution with deionized water or butyl acetate as outlined above).

[0112] 3. Color value (L * , a * , b * ) and ΔE * s Measurement L * a * b * Color space or L * a * b * Color models (i.e., the CIELAB color model) are known to those skilled in the art. * a * b * Color models are standardized, for example, in DIN EN ISO / CIE 11664-4:2020-03. * a * b *Each perceivable color in the color space is represented by a coordinate in the three-dimensional coordinate system, {L * ,a * ,b *}. * The axis represents the green or red portion of the color, with negative values ​​representing green and positive values ​​representing red. * The axis represents the blue or yellow portion of the color, with negative values ​​representing blue and positive values ​​representing yellow, so a smaller number indicates a more bluish color. * The axis is perpendicular to this plane and represents brightness (luminosity). * The axis has black (L=0) and white (L=100) endpoints. Thus, lower values ​​indicate darker colors. Color value L of the coated substrate (after curing) * , a * and b * is determined according to ASTM E 284-81a after preparation including curing.

[0113] The formation of the black surface and the application of the tinted clear coat composition results in a multi-layer coating: 100 parts of black pigment paste are mixed with 20 parts of mixed clear components (p / B=0.39). This mixture (i.e. the base coat) is applied to a metal panel with a 150 micron wire bar applicator. The layer formed is dried for 10 minutes at room temperature and then for 10 minutes at 80°C. After the panel has cooled to room temperature, the tinted clear coat composition is applied. The tinted clear coat composition is applied with a 100 micrometer wire applicator. The base coat layer and the tinted clear coat layer are co-cured for 30 minutes at a temperature of 130°C.

[0114] This value is measured using the instrument BYK-mac I (BYK-Gardner). Analysis of the cured samples is performed according to the standard operating procedure of the BYK-mac i spectrophotometer for the measurement of color, shine, and graininess. The fully cured sample to be analyzed is wiped with a microfiber cloth. The BYK-mac i instrument is then placed on the substrate surface and measurements are made at angles of -15°, 15°, 25°, 45°, 75°, and 110° using a D65 light source, recording the data for each angle using the CIELab settings. This measurement is performed on each panel in at least five different positions and the values ​​are averaged over the trial and reported.

[0115] L * , a * , b * Using ΔE * s We can calculate ΔE * s represents the distance in the color space of the system under test measured on a black surface having the color of the ideal black surface. The color index L of the ideal black body * 0, a * 0, b * For 0, L * 0=a * 0=b * The distance definition in color space as in DIN EN ISO 11664-4 specifies the color index L measured against a black surface. * , a * , b * The scattering distance ΔE in the color space of the system examined * s applies. TIFF2025502316000001.tif1342

[0116] ΔE * s is a measure of the transparency of a film. The lower the value, the more transparent the measured film is.

[0117] 4. Measurement of jetness (Mc) and blackness (My) The jetness and blackness of the coated substrate are determined by the preparation including curing (3. Color value (L * , a * , b * ) and ΔE * s The blackness (My) is a measure of the degree of blackness, which is directly related to the reflectance, and is defined, for example, in DIN 55979 (04-1989). The blackness (My) of a sample can be quantified by using a suitable spectrophotometer to acquire color data using the general formula My=100*log(Yn / Y). Jetness (Mc) is a color-dependent black value developed by K. Lippok-Lohmer (K. Lippok-Lohmer, Farbe und Lack, 92, p. 1024 (1986)) and is also mentioned in DIN 53235-1 (06-2005) and DIN 53235-2 (06-2005). Jetness (Mc) can be quantified by using a suitable spectrophotometer to obtain color data using the general formula Mc=100*[log(Xn / X)-log(Zn / Z)+log(Yn / Y)]. X, Y, Z are the CIE tristimulus values ​​of the sample being measured. Xn, Yn, Zn are the tristimulus values ​​of the illuminant. In the measurements, the illuminant is the D65 illuminant (simulated daylight CIE standard). Standard 2° standard observation values ​​are normalized for relative luminosity, where Yn=100 results in Xn=95.047 and Zn=108.883. Also reported are the auxiliary 10° observation values ​​of Xn=94.8110, Zn=107.304. These values ​​were measured using the instrument BYK-ma i (BYK-Gardner). Analysis of the cured samples is performed according to the standard operating procedure of the BYK-mac I spectrophotometer, following the measurements of color, sparkle and graininess. The fully cured sample to be analyzed is wiped off with a microfiber cloth. A BYK-mac I instrument is then placed on the substrate surface and measurements are taken at angles of -15°, 15°, 25°, 45°, 75°, and 110° using a D65 illuminant, recording the data for each angle using CIELab settings. The My and Mc values ​​reported below in the experimental section are for measurements at angles of 45° and 110°.

[0118] In certain cases, Mc and Mc define a way to express the transparency of a tinted clearcoat layer: the higher the value, the more transparent.

[0119] 5. Acid value The acid number was determined according to DIN EN ISO 2114 in a homogeneous solution of tetrahydrofuran (THF) / water (9 parts by volume THF and 1 part by volume distilled water) with an ethanolic potassium hydroxide 20 aqueous solution.

[0120] 6. Hydroxyl value The OH number is determined by completely hydrolyzing the excess acetic anhydride remaining after acetylation in a tetrahydrofuran (THF) / dimethylformamide (DMF) solution at room temperature in the presence of 4-dimethylaminopyridine as a catalyst using acetic anhydride, and then performing potentiometric back titration of the acetic anhydride with an alcoholic potassium hydroxide solution, based on R.-P. Krueger, R. Gnauck and R. Algeier, Plaste und Kautschuk, 20, 274 (1982).

[0121] 7.Mass average molecular weight Weight average molecular weights were determined by gel permeation chromatography against polystyrene standards using tetrahydrofuran as the eluent. EXAMPLES

[0122] The following examples further illustrate the invention but are not to be construed as limiting its scope.

[0123] Part I: First, an embodiment is described in which the pigment premix (PP) is prepared separately before being combined with all or part of the clear coat system (CS). In other words: the components of the pigment premix (PP) are combined with the clear coat system (CS) in the form of an already prepared pigment premix (PP).

[0124] 1. Manufacturing of pigment premix (PP) PP(A) As the first pigment premix, the commercial product PR179 Red Andaro Nanotint (Fa.PPG) was used. Pigment premix (A) has a haze of 1.78 (measured as described above, i.e. at 17.5% transmittance adjusted with butyl acetate).

[0125] PP(B) 6 parts by weight (pbw) of EFKA PX 4350 (Fa-BASF SE) were mixed with 1.67 pbw of butyl acetate. 7 parts by weight of Paliogen Maroon L 3920 (Fa.BASF Color and Effects GmbH) were slowly added to this mixture while stirring with a dissolver. The dissolver speed was selected so that an effective pasting was achieved. The duration of the dissolving step was 20 minutes. Then, 18.67 pbw of butyl acetate was added under vigorous stirring with the dissolver.

[0126] The produced mixture was then ground in an agitator-type grinder (DCP with micromedia unit, Fa. Buehler) equipped with grinding beads (Silibeads ZY Extrem 0.25-0.35 mm, Fa. Sigmund Lindner) with a particle size (diameter) of approximately 0.3 mm, up to an energy input of 3000 Wh / kg.

[0127] Then, 5.55 pbw of additional butyl acetate was added and the mixture was further milled to an energy input of 3500 Wh / kg. The final pigment premix had a haze of 4.88 (measured at 17.5% transmittance, adjusted with 61.11 pbw of butyl acetate).

[0128] PP(C) 16 pbw of EFKA PX 4350 (Fa-BASF SE) is mixed with 5.56 pbw of polyester resin dispersed in organic solvent (80% polyester, 20% organic solvent, i.e. 1.3 pbw of cyclohexane, 7.6 pbw of ethyl 3-ethoxypropionate, 5.5 pbw of solvent naphtha 160 / 180, and 5.5 pbw of butyl acetate). The polyester was prepared with adipic acid (6.3 pbw), trimethylolpropane (12 pbw), hexahydrophthalic anhydride (25.2 pbw) and Cardura E10 P (37.2 pbw), had an acid number of 9, and a weight average molecular weight of 2650 g / mol.

[0129] To this mixture, 10.0 pbw of Perriondo Violett 29 2294050 (Fa. Sun Chemical) was slowly added while stirring with a dissolver. The dissolver speed was selected to achieve effective pasting. The duration of the dissolution process was 20 minutes. Then, 24 pbw of butyl acetate was added under vigorous stirring with the dissolver.

[0130] The produced mixture was then ground in an agitator-type grinder (DCP with micromedia unit, Fa. Buehler) equipped with grinding beads (Silibeads ZY Extrem 0.25-0.35 mm, Fa. Sigmund Lindner) with a particle size (diameter) of approximately 0.3 mm, up to an energy input of 4500 Wh / kg.

[0131] The final pigment premix had a haze of 1.4 (measured at 17.5% transmission, adjusted with 44.44 pbw butyl acetate).

[0132] 2. Preparation of pigment paste containing pigment premix and part of clear coat system (CS) The pigment pastes applied according to the invention and for comparative purposes were prepared according to steps (c) and (d).

[0133] Pigment Paste (VAA) 21.4 pbw of PP (A) was vigorously mixed and homogenized with 78.6 pbw of the primary binder component (I) of the clearcoat system specified in Item 3 below and in Tables 1 and 2.

[0134] The comparative pigment paste (VAA) had a haze of 10.4 (17.5% transmittance, adjusted with butyl acetate).

[0135] Pigment Paste (AA) 21.4 pbw of PP (A) was mixed with 78.6 pbw of the main binder component (I) of the clearcoat system. The resulting mixture was ground in an agitator grinder (DCP with Micromedia Unit, Fa. Buehler) equipped with grinding beads (Silibeads ZY Extrem 0.08-0.13 mm, Fa. Sigmund Lindner) with a particle size (diameter) of approximately 0.1 mm, up to an energy input of 1500 Wh / kg, resulting in a haze of 7.4 (17.5% transmittance, adjusted with butyl acetate).

[0136] Pigment paste (VBB) 30 pbw of PP (B) was vigorously mixed with 70 pbw of the main binder component of the clearcoat system (I) and homogenized.

[0137] The comparative pigment paste (VBB) had a haze of 19.1 (17.5% transmittance, adjusted with butyl acetate).

[0138] Pigment Paste (BB): 30.0 pbw of PP (B) was mixed with 70.0 pbw of the main binder component (I) of the clearcoat system. The resulting mixture was ground in an agitator grinder (DCP with Micromedia Unit, Fa. Buehler) equipped with grinding beads (Silibeads ZY Extrem 0.08-0.13 mm, Fa. Sigmund Lindner) with a particle size (diameter) of approximately 0.1 mm, up to an energy input of 1500 Wh / kg, resulting in a haze of 12.3 (17.5% transmittance, adjusted with butyl acetate).

[0139] Pigment Paste (VCC) 5.0 pbw of PP (C) was vigorously mixed and homogenized with 95.0 pbw of the primary binder component (I) of the clearcoat system.

[0140] The comparative pigment paste (VCC) had a haze of 23.1 (17.5% transmittance, adjusted with butyl acetate).

[0141] Pigment Paste (CC): 5.0 pbw of PP (C) was mixed with 95.0 pbw of the main binder component (I) of the clearcoat system. The resulting mixture was ground in an agitator grinder (DCP with Micromedia Unit, Fa. Buehler) equipped with grinding beads (Silibeads ZY Extrem 0.08-0.13 mm, Fa. Sigmund Lindner) with a particle size (diameter) of about 0.1 mm, up to an energy input of 1500 Wh / kg, resulting in a haze of 17.3 (17.5% transmittance, adjusted with butyl acetate).

[0142] 3. Clear Coat System (CS) A two-component coating system was provided, comprising a main binder component (I) and a hardener component (II). For this purpose, the two components (I) and (II) were prepared by mixing the respective components in the order as shown in Tables 1 and 2.

[0143] [Table 1]

[0144] [Table 2]

[0145] 4. Preparation of Tinted Clearcoat Compositions and Multi-Layer Coatings Prepared Therefrom Different inventive and comparative tinted clearcoat compositions were prepared. * , a * , b * ) and ΔE * s According to "Measurement of Jetness (Mc) and Blackness (My)" (see above), multilayer coatings are prepared and analyzed with respect to their color / optical properties, so that the measured parameters can be correlated with the transparency (see the "Methods" chapter above for details).

[0146] TCC 1Va: 3.41 pbw of pigment premix PP (A) (PR179 Red Andaro Nanotint (Fa.PPG)) was mixed with 96.58 pbw of the main binder component (I) and a further 33 pbw of the hardener component (II).

[0147] The prepared multi-layer coating has the following properties:

[0148] [Table 3]

[0149] TCC-1Vb: 16.26 pbw of pigment paste (VAA) was mixed with 83.74 pbw of the main binder component (I) and a further 33 pbw of the hardener component (II).

[0150] The properties of the prepared multi-layer coating were comparable to those prepared using TCC1Va (above).

[0151] TCC 1: 16.26 pbw of pigment paste (AA) was mixed with 83.74 pbw of the main binder component (I) and a further 33 pbw of the hardener component (II).

[0152] The prepared multi-layer coating has the following properties:

[0153] [Table 4]

[0154] The results indicate that the transparency of the multilayer coatings prepared using TCC 1 is significantly higher.

[0155] TCC 2Va: 16.26 pbw of pigment paste (VBB) was mixed with 83.74 pbw of the main binder component (I) and a further 33 pbw of the hardener component (II).

[0156] The prepared multi-layer coating has the following properties:

[0157] [Table 5]

[0158] TCC 2Vb 4.88 pbw of the pigmented premix PP (B) was mixed with 95.12 pbw of the main binder component (I) and a further 33 pbw of the hardener component (II).

[0159] The properties of the prepared multi-layer coating were comparable to those prepared using TCC2Va (above).

[0160] TCC 2: 16.26 pbw of pigment paste (BB) was mixed with 83.74 pbw of the main binder component (I) and a further 33 pbw of the hardener component (II).

[0161] The prepared multi-layer coating has the following properties:

[0162] [Table 6]

[0163] The results indicate that the transparency of the multilayer coatings prepared using TCC 2 is significantly higher.

[0164] TCC 3Va: 80.64 pbw of pigment paste (VCC) was mixed with 19.36 pbw of the main binder component (I) and a further 33 pbw of the hardener component (II).

[0165] The prepared multi-layer coating has the following properties:

[0166] [Table 7]

[0167] TCC 3Vb 4.03 pbw of the pigmented premix PP (C) was mixed with 95.97 pbw of the main binder component (I) and a further 33 pbw of the hardener component (II).

[0168] The properties of the prepared multi-layer coating were comparable to those prepared using TCC3Va (above).

[0169] TCC 3: 80.64 pbw of pigment paste (CC) was mixed with 19.36 pbw of the main binder component (I) and a further 33 pbw of the hardener component (II).

[0170] The prepared multi-layer coating has the following properties:

[0171] [Table 8]

[0172] The results indicate that the transparency of the multilayer coatings prepared using TCC 3 is significantly higher.

[0173] The overall results show that lower haze of the pigment premix / pigment paste correlates to improved properties of the multi-layer coating within one and the same pigment premix / pigment paste system combined with an applied clear coat system. The data also shows that lower haze, and therefore better properties, are achieved by the specific grinding step (d).

[0174] However, the data also show that such haze adjustment alone is not sufficient to obtain good properties of the final multilayer coating. Instead, this effect is clearly overcompensated by the grinding step (d) and the choice of whether or not to perform this step, respectively. For example, this is observed when comparing TCC 1Va (use of PP (A) with a haze of 1.78) with TCC 1 (use of pigment paste (AA) with a haze of 7.4), where TCC 1 achieves significantly better properties of the final multilayer coating. The same trend is observed when comparing TCC2 and TCC3 with their respective comparative examples.

[0175] Part II Secondly, embodiments are described in which the pigment premix (PP) is not prepared before combining with all or part of the clearcoat system (CS). Instead, the individual components of the pigment premix (PP) are combined with the clearcoat system (CS) in one mixing and / or dispersing operation. In other words: combining all or part of the clearcoat system (CS) with at least one component of the pigment premix (PP) in step (c) is carried out in one mixing operation. The clearcoat system (CS) is the same as that applied in Part I above.

[0176] 1. Preparation of pigment paste containing pigment premix and part of clear coat system (CS) The pigment paste applied according to the invention was prepared according to steps (c) and (d).

[0177] Pigment paste (DD) X) 6 parts by weight of EFKA PX 4350 (Fa-BASF SE) were mixed with 2.05 parts by weight of butyl acetate. 7.0 pbw of Paliogen Maroon L 3920 (Fa.BASF Color and Effects GmbH) were slowly added to this mixture while stirring with a dissolver. The dissolver speed was selected so that an effective pasting was achieved. The duration of the dissolving step was 30 minutes. Then, under vigorous stirring with the dissolver, 34.95 parts by weight of butyl acetate and 50.0 parts by weight of the main binder component (I) of the clear coat system were added.

[0178] The resulting mixture was ground in an agitator-type grinder (ZWM, Fa. Netzsch) equipped with grinding beads (Silibeads ZY Extrem 0.6-0.8 mm, Fa. Sigmund Lindner) with a particle size (diameter) of approximately 0.7 mm, up to an energy input of 140 Wh / kg.

[0179] Y) The mixture obtained is then further treated in a second grinding step, i.e. ground with an agitator grinder (DCP with Micromedia Unit, Fa. Buehler) equipped with grinding beads (Silibeads ZY Extrem 0.08-0.13 mm, Fa. Sigmund Lindner) having a particle size (diameter) of about 0.1 mm, up to an energy input of 2200 Wh / kg, obtaining a haze of 2.48 (17.5% transmittance, adjusted with butyl acetate).

[0180] In an alternative approach, step X) is not milled but is carried out by a powder wetting device, i.e. an in-line disperser with a rotor-stator system. Thereby, 6 pbw of EFKA PX 4350 (Fa-BASF SE), 37.0 pbw of butyl acetate and 50.0 pbw of the main binder component (I) of the clear coat system are fed into a powder wetting device (e.g. Conti-TDS, Fa. Ystral, or CMX, Fa. IKA) and then mixed. 7.0 pbw of Paliogen Maroon L 3920 (Fa. BASF Color and Effects GmbH) are then added and dispersed. The dispersion speed is selected so that an effective pasting is achieved. This paste is then transferred to a further in-line disperser, i.e. a disperser with an ultra-fine rotor-stator geometry (e.g. Ultra-Turrax or Dispax reactor, Fa. IKA) and further dispersed until transfer to the agitator type mill (step B above) is possible.

[0181] Pigment Paste (EE) X) 5 parts by weight of EFKA PX 4310 (Fa-BASF SE) are mixed with 2.8 pbw of polyester resin dispersed in organic solvent (80% polyester, 20% organic solvent, i.e. 1.3 pbw of cyclohexane, 7.6 pbw of ethyl 3-ethoxypropionate, 5.5 pbw of solvent naphtha 160 / 180, and 5.5 pbw of butyl acetate). The polyester was prepared with adipic acid (6.3 pbw), trimethylolpropane (12 pbw), hexahydrophthalic anhydride (25.2 pbw) and Cardura E10 P (37.2 pbw), had an acid number of 9, and a weight average molecular weight of 2650 g / mol.

[0182] To this mixture, 5.0 pbw of Perriondo Violett 29 2294050 (Fa. Sun Chemical) was slowly added while stirring with a dissolver. The dissolver speed was selected to achieve effective pasting. The duration of the dissolving step was 30 minutes. Then, under vigorous stirring with the dissolver, 37.2 pbw of butyl acetate and 50.0 pbw of the main binder component (I) of the clear coat system were added.

[0183] The resulting mixture was ground in an agitator-type grinder (ZWM, Fa. Netzsch) equipped with grinding beads (Silibeads ZY Extrem 0.6-0.8 mm, Fa. Sigmund Lindner) with a particle size (diameter) of approximately 0.7 mm, up to an energy input of 140 Wh / kg.

[0184] Y) The mixture obtained is then further treated in a second grinding step, i.e. ground with an agitator grinder (DCP with Micromedia Unit, Fa. Buehler) equipped with grinding beads (Silibeads ZY Extrem 0.08-0.13 mm, Fa. Sigmund Lindner) having a particle size (diameter) of about 0.1 mm, up to an energy input of 2000 Wh / kg, to obtain a haze of 1.65 (transmittance of 17.5%, adjusted with butyl acetate).

[0185] For the pigment pastes (EE), the alternative step X) is also applicable, carried out by means of a powder wetting device, i.e. an in-line disperser equipped with a rotor-stator system, thus providing a paste which can be transferred to the stirred mill of step Y).

[0186] 2. Preparation of Tinted Clearcoat Compositions and Multi-Layer Coatings Prepared Therefrom Pigment pastes (DD) and (EE) were used to prepare two different inventive tinted clearcoat compositions. Again, the "Color Value (L * , a * , b * ) and ΔE *s According to "Measurement of Jetness (Mc) and Blackness (My)" (see above), multilayer coatings are prepared and analyzed with respect to their color / optical properties, so that the measured parameters can be correlated with the transparency (see the "Methods" chapter above for details).

[0187] TCC 4: 4.94 pbw of the pigment paste (DD) was mixed with 95.06 pbw of the main binder component (I) and a further 33 pbw of the hardener component (II).

[0188] The prepared multi-layer coating has the following properties:

[0189] [Table 9]

[0190] The results clearly show that the transparency of the multilayer coatings prepared with TCC 4 is significantly higher compared to the comparative systems mentioned above (see Part I). The results also show that the multilayer coatings based on TCC 4 have the same level of transparency or even better than the multilayer coatings based on TCC 2 (also based on the same type of pigment, but involving a separate production of the pigment premix (PP) instead of combining its components with the clear coat system (CS) in one mixing step). Furthermore, the energy consumption during grinding is significantly lower in the case of TCC 4 than during the production of TCC 2.

[0191] TCC 5 8.10 pbw of pigment paste (EE) was mixed with 91.9 pbw of the main binder component (I) and a further 33 pbw of the hardener component (II).

[0192] The prepared multi-layer coating has the following properties:

[0193] [Table 10]

[0194] The results clearly show that the transparency of the multilayer coatings prepared with TCC 5 is significantly higher compared to the comparative systems mentioned above (see Part I). The results also show that the multilayer coatings based on TCC 5 have the same level of transparency or even better than the multilayer coatings based on TCC 3 (also based on the same type of pigments, but involving a separate production of the pigment premix (PP) instead of combining its components with the clear coat system (CS) in one mixing step). Furthermore, the energy consumption during grinding is significantly lower in the case of TCC 5 than during the production of TCC 3.

Claims

1. at least one binder resin (A) having a functional group (i); at least one curing agent (B) having a functional group (ii) which is reactive with the functional group (i), and at least one pigment (C) A tinted clear coat composition (TCC) comprising: The tinted clear coat composition (TCC) comprises: (a) providing a clear coat system (CS) comprising at least one binder resin (A) and at least one curing agent (B); (b) providing at least one pigment premix (PP) component comprising at least one pigment (C); (c) combining all or a portion of said clear coat system (CS) with components of said at least one pigment premix (PP); (d) grinding the mixture obtained in step (c); (e) mixing the mixture obtained in step (d) with a deficient portion of the tinted clear coat composition (TCC), if applicable; The tinted clear coat composition (TCC) can be prepared by

2. 10. The tinted clearcoat composition (TCC) of claim 1, wherein said pigment premix (PP) is not separately prepared prior to combination with all or a portion of said clearcoat system (CS).

3. Its production, (a) providing a clear coat system (CS) comprising at least one binder resin (A) and at least one curing agent (B); (b) providing at least one pigment premix (PP) component comprising at least one pigment (C); (c) combining a portion of said clear coat system (CS) with components of said at least one pigment premix (PP), said portion of said clear coat system (CS) being combined containing at least one binder resin (A); (d) grinding the mixture obtained in step (c); (e) mixing the mixture obtained in step (d) with the remaining portion of the clear coat system (CS) and, if applicable, with the remaining portion of the tinted clear coat composition (TCC); 3. The tinted clearcoat composition (TCC) of claim 1 or 2, comprising:

4. 4. The tinted clear coat composition (TCC) of claim 3, wherein the clear coat system (CS) is a two-component clear coat system comprising a main binder component (I) comprising at least one binder resin (A) and a hardener component (II) comprising at least one hardener (B), and the portion of the clear coat system (CS) applied in step (c) is all or a part of the main binder component (I).

5. 5. The tinted clearcoat composition (TCC) of claim 4, wherein the portion of the clearcoat system (CS) applied in step (c) is part of the main binder component (A).

6. The tinted clear coat composition (TCC) according to claim 4, wherein in step (c) the weight ratio of all or part of said primary binder component (I) to said at least one pigment premix (PP) component is from 10:90 to 99:1, more preferably from 15:85 to 98:5, even more preferably from 20:80 to 97:

3.

7. 3. The tinted clear coat composition (TCC) of claim 1 or 2, wherein the grinding step (d) is carried out by at least two different sub-steps, where a first sub-step is carried out with an energy input of 50 to 1000 Wh / kg and a second sub-step is carried out with an energy input of more than 1000 to 5000 Wh / kg.

8. 5. The tinted clearcoat composition (TCC) of claim 4, wherein the at least one binder resin (A) has hydroxyl groups as functional groups and the curing agent (B) is a polyisocyanate having free isocyanate groups.

9. The tinted clearcoat composition (TCC) according to claim 1 or 2, wherein at least one pigment (C) is an organic pigment.

10. The tinted clearcoat composition (TCC) of claim 1 or 2, which is a solvent-based coating composition.

11. 3. The tinted clear coat composition (TCC) according to claim 1 or 2, wherein said pigment (C) is present in a total amount of 0.05 to 10 wt-%, preferably 0.1 to 4 wt-%, very preferably 0.1 to 1.0 wt-%, based on the total weight of the tinted clear coat composition.

12. 3. The tinted clear coat composition (TCC) according to claim 1 or 2, wherein combining all or part of said clear coat system (CS) with the components of said at least one pigment premix (PP) in step (c) is carried out in a single mixing operation.

13. The following steps: (a) providing a clearcoat system (CS) comprising at least one binder resin (A) and at least one curing agent (B); (b) providing at least one pigment premix (PP) component comprising at least one pigment (C); (c) combining all or a portion of said clear coat system (CS) with components of said at least one pigment premix (PP); (d) grinding the mixture obtained in step (c); (e) mixing the mixture obtained in step (d) with a deficient portion of a tinted clear coat composition (TCC), if applicable; 3. A method for producing the tinted clearcoat composition (TCC) of claim 1 or 2, comprising:

14. The following steps: (1) providing an optionally precoated substrate; (2) applying a pigmented basecoat composition to the optionally precoated substrate according to step (1), thereby producing a first basecoat film; (3) optionally applying at least one additional pigmented basecoat composition different from the basecoat composition applied in step (2) to the first basecoat film present on the substrate after step (1), thereby producing at least one additional basecoat film on the first basecoat film; (4) applying a tinted clearcoat composition to the top basecoat film produced in step (2) and optional step (3), thereby producing a tinted clearcoat film on said top basecoat film; A method for producing a multi-layer coating comprising:

3. The method of claim 1, wherein the tinted clearcoat composition applied in step (4) is the tinted clearcoat composition (TCC) of claim 1 or 2.

15. Step (5), i.e. (5) Co-curing the films applied in steps (2) to (4). The method of claim 14 further comprising:

16. 15. The method of claim 14, wherein the basecoat composition applied in step (2) and optional step (3) is a waterborne composition.

17. 3. Use of the tinted clear coat composition (TCC) according to claim 1 or 2 for improving the colour properties of a coating, in particular a multi-layer coating.

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