Coating composition comprising a pigment paste comprising an organic pigment and an aryl modified branched reaction product - Patents.com

Abstract

The present application relates to a coating composition comprising a pigment paste, the pigment paste comprising an organic pigment and an aryl modified branched reaction product (P) which reaction product (P) comprises, in reacted form, a polyhydroxy-functional core portion (a) and a shell portion (b) comprising polyalkylene oxide units and aromatic units, the polyalkylene oxide units and aromatic units being covalently bonded to the core portion via units comprising functional groups reactive with hydroxy groups. The present application also relates to a method of producing a cured coating on a substrate using said coating composition.

Description

[Technical field]

[0001] The present invention relates to a coating composition comprising a particular pigment paste, i.e. a pigment paste comprising an organic pigment and a particular aryl modified branched reaction product. The present invention also relates to a method for preparing said coating composition, in particular an aqueous coating composition. The present invention also relates to a coating (coating layer) prepared from said composition. The present invention provides a coating composition and a pigment paste, respectively, which allow a finely distributed and stable integration of an organic pigment with an optimal, and therefore small, particle size, thereby enabling optimal color properties of the coating layer, e.g. high transparency (low scattering) and excellent color depth, in particular in multi-layer coatings. [Background technology]

[0002] This section provides information that is useful for understanding the invention, but is not necessarily prior art. All references mentioned below are incorporated herein by reference in their entirety.

[0003] In coating compositions, the pigments used to provide the color must be reduced and stabilized at an optimal particle size (different for different pigments) for the coating to exhibit optimal color properties. To obtain optimal color properties with certain organic pigments, the particle size of the pigment must be reduced much more than typical inorganic pigments. The adsorption properties of organic pigments are also different, which affects the color properties. Typically, resins are used to facilitate the mechanical reduction and subsequent stabilization of the pigment particles. Because the physical / chemical properties of organic pigments are different from inorganic pigments and the optimal particle size of organic pigments is much smaller, resins used to disperse inorganic pigments are not effective in making optimal organic pigment dispersions. Furthermore, resins specialized for dispersing organic pigments are expensive. The above difficulties and challenges are even more severe in the case of aqueous coating compositions, i.e., compositions that do not exclusively or primarily contain organic solvents (also called solvents) as their dispersion medium, but instead contain a significant proportion of water as their dispersion medium.

[0004] In US2019 / 0106592A1 it is described that aryl modified highly branched polyols are applied in a first variant in a water-based (i.e. aqueous) composition, or in a second variant in a solvent-based composition. While in the water-based composition storage stability and low VOC are achieved in systems containing water-sensitive pigments without the use of chromium compounds, the publication refers to solvent-based compositions containing small amounts of organic pigments and resulting in optimal color properties of the produced coating layer.

[0005] US2016 / 0017175A1 describes a coating composition comprising a flexible hyperbranched polyol prepared by the steps of: (a) reacting a polyol containing at least three hydroxyl groups with an aliphatic dicarboxylic acid having 6 to 36 carbon atoms or an esterifiable derivative of an aliphatic dicarboxylic acid to form a hydroxyl-functional core; (b) reacting the core with a cyclic carboxylic acid anhydride to form a carboxylic acid-functional first intermediate product; and (c) reacting the first intermediate product with an epoxide-functional compound having one epoxide group to form a hyperbranched polyol. The coating composition can be cured into a coating layer having excellent flexibility.

[0006] In US Patent No. 6,646,049, a binder for a coating composition is disclosed that includes a main resin polyol in combination with a highly branched polyol as a reactive intermediate and at least one crosslinker. The main resin polyol is at least one of polyester polyol, polyether polyol, and polyacrylate. The highly branched polyester polyol can be used as a reactive diluent that crosslinks with isocyanates, isocyanurates, epoxides, anhydrides, or their corresponding polyacids and / or aminoplasts to form binders with specific properties to help control the rheology of the coating system. The highly branched polyol, the main resin polyol, or both, optionally contain carbamate functional groups. Coating compositions are made using these binders together with additional ingredients. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] US2019 / 0106592A1 [Patent Document 2] U.S. Patent No. 6,646,049 Summary of the Invention [Problem to be solved by the invention]

[0008] It remains desirable to improve coating compositions containing organic pigments with respect to optimum particle size and dispersion behavior, including dispersion stability, of the pigments, leading to coating layers exhibiting optimum color properties. Also, there is a need for coating compositions that are economically viable alternatives to compositions containing specialty resins dedicated to dispersing organic pigments, while being better able to stabilize fine organic pigment particles than conventional dispersing resins. [Means for solving the problem]

[0009] It has now been found that the above identified problems can be solved by a coating composition comprising a pigment paste, the pigment paste comprising an organic pigment and an aryl modified branched reaction product (P), which reaction product (P) in reacted form comprises (a) a polyhydroxy-functional core moiety, and (b) a shell portion comprising polyalkylene oxide units and aromatic units; wherein the polyalkylene oxide units and the aromatic units are covalently attached to the core moiety via units that contain functional groups that are reactive with hydroxy groups.

[0010] The novel coating composition is hereinafter also referred to as the inventive composition. Preferred embodiments of the invention are evident from the following description and the dependent claims.

[0011] Also provided by the present invention are methods for producing the aforementioned pigment pastes, and methods for producing the aforementioned coating compositions, especially aqueous coating compositions.

[0012] The present invention also provides coating layers prepared from the aforementioned compositions, particularly multi-coat coating systems in which one layer is prepared with a composition of the present invention.

[0013] It has become clear that by using the coating composition of the present invention, outstanding performance properties of the coating layers and the respective multi-coat paint systems can be achieved. Worth mentioning are optimal color properties, which are due to the excellent particle size and dispersion behavior of the pigments, including dispersion stability, in the coating composition, especially in the aqueous coating composition. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] For parameters or similar properties used in the definition, the respective measurement methods are stated in the specification and / or in the experimental section.

[0015] The term "one" (or an equivalent term denoting the singular) is to be understood as "at least one" unless expressly defined otherwise. The definition of such a term can be, for example, "only one" or "monofunctional", thus clarifying that the term refers to only "one" and not "more than one".

[0016] The coating composition of the present invention comprises a pigment paste. As known to those skilled in the art, a pigment paste is an intermediate product that is applied to the coating composition to properly integrate the pigment and the respective particles in the composition. Pigment pastes in the coating industry significantly facilitate the technically complex process of dispersing pigments and thus integrating and stabilizing them in the composition. The pigments in the paste are optimally wetted and very well dispersed, so that an improved distribution is also obtained in the coating composition. This of course results in improved performance properties of the coating material and the coating system produced therefrom, such as a particularly homogeneous color or color distribution in the coating system. However, in the production of these pastes, precisely matched paste binder components must be used in order to obtain an optimally adjusted paste. Without an individual match and precise selection of the paste binder, it is usually not possible to optimally disperse a particular pigment and the performance properties of the final coating system are also not optimal. In other words, the paste binder plays a major role during paste preparation, i.e. when the pigment and paste binder, and the solvent and / or water, and if necessary further conventional additives, are mixed and ground / dissolved to reduce the particle size of the pigment, finely distribute and stably disperse it. This is especially a challenge for organic pigments, both in terms of particle size reduction and stabilization / dispersion, as outlined in the introduction. Surprisingly, the aryl modified branched reaction products (P) are perfectly suitable as such paste binders, which means that the above mentioned technical advantages are achieved.

[0017] From the above, in the context of the present invention, the expression "coating composition comprising a pigment paste" is understood to mean that the pigment paste is included in the coating composition as such, i.e. pre-prepared, i.e. an intermediate product that is mixed with the further components of the composition after its own production. Thus, the compounds and solvents that the pigment paste should contain in its finished form are mixed / dispersed in this pigment paste before the paste itself is added as part of the preparation of the coating composition according to the invention. The pigment paste is therefore obviously a composition itself that can be stored and transported separately before it is applied at some point in the production of the coating composition.

[0018] The first component of the pigment paste is a specific reaction product (P).

[0019] The reaction product (P) comprises a core portion and a shell portion. The terms core portion and shell portion are applied to clarify and distinguish the two essential portions of the reaction product (P), namely, the first portion (i.e., the core portion) which is primarily located in the center of the resulting molecule, and the second portion which is covalently bonded to the core portion and is therefore primarily located in the outer region of the resulting molecule. The term "primary" here refers to the fact that, at least for reasons related to technical synthesis, theoretically idealized quantitative transformations do not always completely match theoretical expectations. Rather, as known to those skilled in the art, for example, side reactions are expected. Also, the term "portions" is understood to represent chemical groups and units that do not necessarily have to be directly covalently bonded to each other alone, since they belong to the same moiety. For example, the shell portion comprises individual units that are not directly covalently bonded to react with different hydroxyl groups of the core portion.

[0020] The reaction product (P) contains, in reacted form, a polyhydroxy-functional core moiety, ie, the hydroxy groups of the molecules which make up the core have been reacted as described below.

[0021] The molecules (or compounds) that make up the core are named compounds (c) and are polyhydroxy-functional, i.e., contain, on average, at least three hydroxy groups. This is also consistent with the fact that the reaction product (P) is branched, i.e., there is at least one branched side chain that allows at least three reactive side chains for the three branches pointing outwards. The term "on average" takes into account that both (cI) monomeric polyhydroxy-functional and / or (cII) reaction product / oligomeric / polymeric (also called prepolymer) compounds can be applied as the molecules that make up the core. As known to those skilled in the art, class (cII) includes compounds such as oligomeric or polymeric compounds that can only be described by averaged parameters, such as, for example, average molecular weight or average hydroxy functionality.

[0022] Compound (c) is selected from monomeric polyols (cI) such as triols, dimers of triols, tetrols, dimers of tetrols, and sugar alcohols. Non-limiting examples of suitable polyols having three or more hydroxyl groups include glycerol, trimethylolmethane, trimethylolethane, trimethylolpropane, 2,2,3-trimethylolbutane-1,4-diol, 1,2,4-butanetriol, 1,2,6-hexanetriol, tris(hydroxymethyl)amine, tris(hydroxyethyl)amine, tris(hydroxypropyl)amine, erythritol, pentaerythritol, diglycerol, higher condensates of triglycerol or glycerol, di(trimethylolpropane), di(pentaerythritol), tri(pentaerythritol) pentaerythritol ethoxylate, pentaerythritol ... These include polyetherols of functionality 3 or greater based on alcohols of functionality 3 reacted with ritol propoxylate, trishydroxymethyl isocyanurate, tris(hydroxyethyl) isocyanurate (THEIC), tris(hydroxypropyl) isocyanurate, inositol, or sugars such as glucose, fructose or sucrose, sugar alcohols such as xylitol, sorbitol, mannitol, threitol, erythritol, adonitol (ribitol), arabitol (lyxitol), xylitol, dulcitol (galactitol), maltitol, isomalt, ethylene oxide, propylene oxide and / or butylene oxide.

[0023] In certain preferred embodiments, polyol (cI) is at least one of erythritol, pentaerythritol, di(pentaerythritol), tri(pentaerythritol), trimethylolethane, trimethylolpropane, trimethylolbutane, glycerol, ditrimethylolethane, ditrimethylolpropane, pentaerythritol ethoxylate, and pentaerythritol propoxylate.

[0024] Also, as outlined above, polyol (c) may be selected from compounds (cII) which are reaction product / oligomeric / polymeric (prepolymer) compounds. Compounds which can be prepared by reaction of monomeric polyols with at least difunctional compounds capable of linking two or more polyols together are preferred. Suitable and preferred monomeric polyols are polyols (cI) as mentioned above. Suitable and preferred compounds for reaction with polyols are aliphatic dicarboxylic acids having 6 to 36 carbon atoms or esterifiable derivatives of such aliphatic dicarboxylic acids. Another class of preferred compounds (cII) can be prepared by reaction of monomeric polyols with monocarboxylic acids having at least two hydroxy groups, such as dimethylolpropionic acid.

[0025] The above aliphatic dicarboxylic acids having 6 to 36 carbon atoms or esterifiable derivatives of aliphatic dicarboxylic acids may be linear, branched, or cyclic, and preferably, the cyclic dicarboxylic acids contain a non-cyclic segment of at least 6 carbon atoms (including the carbon atom of the carboxylic acid group). Examples of suitable dicarboxylic acids include, but are not limited to, adipic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid (brassylic acid), dodecanedioic acid, traumatic acid, hexadecanedioic acid (thapsic acid), octadecanedioic acid, tetradecanedioic acid, and dimer fatty acids having 36 carbon atoms. In various embodiments, α,ω-dicarboxylic acids and dimer fatty acids having 36 carbon atoms are preferred. It is known that dimer fatty acids having 36 carbon atoms may have multiple isomers. Dimer fatty acids are commercially available, for example, from BASF under the trade name EMPOL®, from Arizona Chemical under the trade name UNIDYME™, from Croda International Plc under the trade name Pripol™, and from Emery Oleochemicals as EMERY® Dimer Acid. Esterifiable derivatives of dicarboxylic acids having 6 to 36 carbon atoms include their mono- or diesters with aliphatic alcohols having 1 to 4 carbon atoms, preferably the methyl and ethyl esters, and the anhydrides. A highly preferred carboxylic acid is adipic acid.

[0026] For the preparation of such preferred compounds (cII), the ratio of moles of monomeric polyol to moles of dicarboxylic acid or esterifiable derivative of an aliphatic dicarboxylic acid is preferably 2.0-2.5, preferably 2.0-2.2, and more preferably 2.0-2.07 moles of polyol per mole of dicarboxylic acid or esterifiable derivative of an aliphatic dicarboxylic acid.

[0027] The reaction of preferably monomeric polyol with a preferred aliphatic dicarboxylic acid or esterifiable derivative, i.e., the esterification reaction, may be carried out by known standard methods. The reaction conditions, such as temperature, catalyst, solvent, and reaction process, can be individually adapted. For completeness, reference is made to

[0024] to

[0029] of US2016 / 0017175A1 and

[0089] to

[0094] of US2019 / 0106592A1 and step (a0) described therein, which are expressly and completely incorporated herein by reference.

[0028] The preparation of compounds of class (cII) obviously means increasing the (average) number of hydroxyl functions per molecule and therefore increasing the number of branched side chains of the core moiety and therefore increasing the branched character of the reaction product (P).

[0029] Specifically, the (average) number of hydroxyl groups in the compound constituting the primary core moiety is 3-20, more preferably 6-16.

[0030] For compounds to which the average number of hydroxy groups applies, this number is determined by analysis of the number average molecular weight and the hydroxyl content.

[0031] In certain embodiments where core compound (c) is a compound (cII), in particular a reaction product of a polyol (cI) with an aliphatic dicarboxylic acid or an esterifiable derivative of an aliphatic dicarboxylic acid having 6 to 36 carbon atoms, it is advantageous to carry out the reaction with an aromatic carboxylic acid as described below simultaneously with the preparation of compound (cII), i.e. core compound (cII) is prepared simultaneously with the step of adding the aromatic units of the shell portion of reaction product (P).

[0032] The reaction product comprises, as a first essential part, a shell part comprising aromatic units in reacted form. The aromatic units are covalently linked to the core part via units comprising functional groups reactive with hydroxyl groups. That is, the aromatic units are covalently linked to the core part by reaction of the respective functional groups with the hydroxyl groups of the core. Thus, the aromatic units are introduced via a compound comprising aromatic units and units comprising at least one functional group reactive with hydroxyl groups. Such compounds are also named compounds (d). The aromatic units may also be introduced in a two-step procedure, i.e., by first reacting the core part and a part of its hydroxyl groups, respectively, with a first compound (d1) having a first functional group reactive with hydroxyl groups and a second functional group reactive with a second compound (d2), whereby this second compound (d2) comprises an aromatic group and a functional group reactive with the second functional group of compound (d1).

[0033] Compound (d) may be selected and varied from a wide range of compounds, as long as it meets the above criteria. Potential functional groups reactive with hydroxyl groups are, for example, carboxy groups, isocyanate groups or anhydride groups. Those skilled in the art know which compounds are generally applicable and can also select the respective reaction conditions, for example, to achieve the addition of the respective aromatic units.

[0034] In a preferred embodiment, the aromatic units are added by reaction of the hydroxy group of the core compound with an aromatic or araliphatic (both aromatic and aliphatic) carboxylic acid, i.e., an esterification reaction of the carboxylic acid group with the hydroxy group. Again, such esterification may be carried out by known standard methods. For completeness, reference is made to

[0089] to

[0094] of US2019 / 0106592A1 and to step (a) described therein. These paragraphs are expressly and entirely incorporated herein by reference.

[0035] Thus, preferred compounds (d) are selected from aromatic or araliphatic (both aromatic and aliphatic) carboxylic acids. Particularly preferred are compounds of formula (I): [ka] is a carboxylic acid of In the formula, Ar is an optionally substituted aryl group which is a monocyclic or fused polycyclic aromatic hydrocarbon group, m is 0 or 1, and n is 0 or an integer from 1 to 8.

[0036] In certain embodiments, Ar is an optionally substituted monocyclic aromatic hydrocarbon group, preferably a phenyl group optionally having 1 to 3 substituents selected from the group consisting of linear or branched alkyl of 1 to 6 carbon atoms, alkoxy of 1 to 6 carbon atoms, alkoxyalkyl whose alkyl moiety has 1 to 6 carbon atoms, halo, phenyl, and hydroxy. In certain embodiments, Ar is an optionally substituted condensed polycyclic aromatic hydrocarbon group, preferably a naphthyl group, anthranyl group, or phenanthryl group optionally having 1 to 3 substituents selected from the group consisting of linear or branched alkyl of 1 to 6 carbon atoms, alkoxy of 1 to 6 carbon atoms, alkoxyalkyl whose alkyl moiety has 1 to 6 carbon atoms, halo, phenyl, and hydroxy.

[0037] In certain embodiments, the carboxylic acid (d) has the formula (II) or (III): [ka] It is expressed as In formulae (II) and (III), n is 0 or an integer from 1 to 8, preferably 0 or an integer from 1 to 4, especially 0 or 1, o is 0 or an integer from 1 to 3, and each R, if present, is independently selected from the group consisting of straight or branched chain alkyl of 1 to 6 carbon atoms, alkoxy of 1 to 6 carbon atoms, alkoxyalkyl in which the alkyl portion has 1 to 6 carbon atoms, halo, phenyl, and hydroxy. Examples of compounds according to formulae (II) and (III) are illustrated below:

[0038] [ka]

[0039] In certain embodiments, the aromatic carboxylic acid of step (a) has formula (IV) or (IV): [ka] is an aryloxy aromatic carboxylic acid represented by the formula: In formulae (IV) and (V), n is 0 or an integer from 1 to 8, preferably 0 or an integer from 1 to 4, especially 0 or 1, o is 0 or an integer from 1 to 3, and each R, if present, is independently selected from the group consisting of straight or branched chain alkyl of 1 to 6 carbon atoms, alkoxy of 1 to 6 carbon atoms, alkoxyalkyl in which the alkyl portion has 1 to 6 carbon atoms, halo, phenyl, and hydroxy. Examples of compounds according to formulae (IV) and (V) are illustrated below: [ka]

[0040] In various embodiments, the equivalent ratio of hydroxyl groups of the core compound to carboxylic acid groups of the aromatic or araliphatic carboxylic acid is 1.5 to 3.5 equivalents of hydroxyl groups per carboxylic acid group. In the case of the simultaneous formation of the core compound as described above, i.e., for example, the reaction of polyol (cI) with an aliphatic dicarboxylic acid having 6 to 36 carbon atoms or an esterifiable derivative of an aliphatic dicarboxylic acid, the amount of hydroxyl groups of the core compound is quite obviously determined by subtracting the amount of carboxylic acid groups of the dicarboxylic acid from the amount of hydroxyl groups of polyol (cI).

[0041] The reaction product contains, as a second essential part, polyalkylene oxide units in the form reacted into the shell part. These units are covalently bonded to the core part via units containing functional groups reactive with hydroxyl groups. That is, the polyalkylene oxide units are covalently bonded to the core part by reaction of the respective functional groups with the hydroxyl groups of the core. Thus, the polyalkylene oxide units are introduced via a compound containing polyalkylene oxide units and units containing functional groups reactive with hydroxyl groups. Such compounds are also named compounds (e). The polyalkylene oxide units may also be introduced in a two-step procedure, i.e., by first reacting the core part and a part of its hydroxyl groups, respectively, with a first compound (e1) having a first functional group reactive with hydroxyl groups and a second functional group reactive with a second compound (e2), whereby this second compound (e2) contains a polyalkylene oxide group and a functional group reactive with the second functional group of compound (e1).

[0042] Compound (e) may be selected and varied from a wide range of compounds, as long as it meets the above criteria. Potential functional groups reactive with hydroxyl groups are, for example, carboxy groups, isocyanate groups and (cyclic) carboxylic anhydride groups. The skilled person knows which compounds are generally applicable and can also select the respective reaction conditions for achieving, for example, the addition of the respective polyalkylene oxide units. Compound (e) is preferably monofunctional with respect to the functional group reactive with hydroxyl groups, because this ensures that compound (e) is added to only one core moiety without a complex reaction process, and not two core moieties are then interconnected / bridged by compound (e).

[0043] In a preferred embodiment, the polyalkylene oxide units are added by reaction of the hydroxyl groups of the core compound with a compound having polyalkylene oxide units and a functional group selected from isocyanate groups, carboxylic acid groups and cyclic carboxylic anhydride groups. Even more preferably, the functional group is selected from isocyanate groups. As mentioned above, compound (e) is preferably monofunctional in that the functional group is reactive with hydroxyl groups. However, it is worth mentioning that in the case of a cyclic carboxylic anhydride group, this group may be formally considered as a group containing two carboxyl groups, i.e., bridging of the two core moieties is in principle possible. However, as known to those skilled in the art, cyclic carboxylic anhydrides are more reactive with hydroxyl groups than free carboxy groups alone due to ring tension, i.e., by controlling the reaction conditions, such as temperature and / or catalyst, it is possible to ensure the reaction of only or at least mainly cyclic anhydrides, which ultimately leads to a reaction product with free carboxylic acid groups. Thus, in view of the preferred monofunctional properties of compound (e) above, in the case of cyclic carboxylic acid anhydrides, the anhydride is considered to be a group reactive with hydroxyl groups, but the resulting free carboxy group is not considered to be such a group, since it is not present prior to the reaction and the general given reactivity may be suppressed by the reaction conditions described above.

[0044] Nevertheless, experience has shown that reaction with monoisocyanate compounds (e) is advantageous with regard to the polydispersity of the resulting reaction products, which is likewise why isocyanate is preferred as the functional group.

[0045] The polyalkylene oxide unit of the reaction product (e) is, for example, -((CH2-CHR1) n -O) m-, where R1 means hydrogen (H) and / or alkyl residues having 1 to 3 carbon atoms, preferably hydrogen and / or methyl, whereby the residues R1 may be identical or different, n means 1 to 3 and m means 10 to 100, preferably 20 to 50. Examples of such units are polytetramethylene oxide, polypropylene oxide, polyethylene oxide or mixed copolymers as block copolymers containing different ones of the aforementioned polyalkylene oxides. Polypropylene oxide and / or polyethylene oxide, and mixed copolymers thereof, are preferred, with polyethylene oxide being particularly preferred.

[0046] This means that in a first preferred embodiment, compounds (e) are selected from compounds having polyoxyalkylene units and only one isocyanate group, while not having any further functional groups reactive with hydroxyl groups.Of course, the preferences defined above with respect to the polyoxyalkylene units also apply in the context of these compounds (e).

[0047] Thus, these compounds (e) can be prepared by reacting a standard poly(alkylene glycol) alkyl ether (i.e., a polyalkylene glycol having one hydroxyl group etherified with an alkyl group) with a diisocyanate compound to give a compound having one isocyanate group.

[0048] As the diisocyanate compound, well-known aliphatic, alicyclic, aliphatic-alicyclic, aromatic, aliphatic-aromatic and / or alicyclic-aromatic diisocyanates may be employed by those skilled in the art. Examples include the following diisocyanates: 1,3- or 1,4-phenylene diisocyanate, 2,4- or 2,6-tolylene diisocyanate, 4,4'- or 2,4'-diphenylmethane diisocyanate, 1,4- or 1,5-naphthylene diisocyanate, diisocyanatodiphenyl ether, tolylene diisocyanate, tetramethylene diisocyanate, ethylethylene diisocyanate, 2,3-dimethylethylene diisocyanate, 1-methyltrimethylene diisocyanate, pentamethylene diisocyanate, 1,3-cyclopentylene diisocyanate, hexamethylene diisocyanate, cyclohexylene diisocyanate, 1,2-cyclohexylene diisocyanate, octamethylene diisocyanate, trimethylhexane diisocyanate, tetramethylhexane diisocyanate, decamethylene diisocyanate. , dodecamethylene diisocyanate, tetradecamethylene diisocyanate, isophorone diisocyanate (IPDI), 2-isocyanatopropylcyclohexyl isocyanate, dicyclohexylmethane 2,4'-diisocyanate, dicyclohexylmethane 4,4'-diisocyanate, 1,4- or 1,3-bis(isocyanatomethyl)cyclohexane, 1,4- or 1,3- or 1,2-diisocyanatosilane cyclohexane, 2,4- or 2,6-diisocyanato-1-methylcyclohexane, 1-isocyanatomethyl-5-isocyanato-1,3,3-trimethylcyclohexane, 2,3-bis(8-isocyanatooctyl)-4-octyl-5-hexylcyclohexene, tetramethylxylylene diisocyanate (TMXDI), such as m-tetramethylxylylene diisocyanate, or mixtures of these diisocyanates.

[0049] Since the reaction conditions of hydroxyl and isocyanate are absolute standards and well known, in the present case, it is important to choose conditions that ensure the reaction of only one isocyanate group with poly(alkylene glycol) alkyl ether.For at least this reason, one particularly preferred isocyanate is isophorone diisocyanate (IPDI).The reason is that the two isocyanate groups of this established and available diisocyanate are not equivalent in terms of reactivity, so that by smart control of reaction conditions, such as the choice of temperature and catalyst, only one-sided reaction of the isocyanate can be ensured (thereby recognizing that, of course, side effects are virtually unavoidable and must be accepted).

[0050] In a second preferred embodiment (but less preferred than the above-mentioned first preferred embodiment with the specific compound (e)), the two above-mentioned compounds (e1) and (e2) are applied.

[0051] Compounds (e1) and (e2) may be selected and varied from a wide range of compounds, as long as they meet the above criteria. The skilled person will know which compounds are generally applicable and will also be able to select the respective reaction conditions, for example, to achieve the addition of the respective polyalkylene oxide units.

[0052] Preferred compounds (e1) are cyclic carboxylic acid anhydride components, such as maleic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, tetrahydrophthalic anhydride, phthalic anhydride, succinic anhydride, trimellitic anhydride, methyltetrahydrophthalic anhydride, adipic anhydride, glutaric anhydride, malonic anhydride, itaconic anhydride, 5-methyl-5-norbornene dicarboxylic anhydride, 1,2-cyclohexane dicarboxylic anhydride, isatoic anhydride, diphenic anhydride, and in particular lower alkyl-substituted anhydrides. Substituted anhydrides, including those selected from butylsuccinic anhydride, hexylsuccinic anhydride, octylsuccinic anhydride, butylmaleic anhydride, pentylmaleic anhydride, hexylmaleic anhydride, octylmaleic anhydride, butylglutaric anhydride, hexylglutaric anhydride, heptylglutaric anhydride, octylglutaric anhydride, alkylcyclohexanedicarboxylic anhydrides, and alkylphthalic anhydrides, such as 4-n-butylphthalic anhydride, hexylphthalic anhydride, and octylphthalic anhydride. Particularly preferred is succinic anhydride.

[0053] Since compound (e1) contains, by definition, two functional groups for reaction (see above), the skilled person will directly understand that, with respect to the preferred cyclic carboxylic anhydrides, and with respect to the fact that these anhydrides can be considered formally as compounds having two carboxyl groups (whereby the first one reacts in the form of a part of the cyclic anhydride to give the second one), with respect to such cyclic carboxylic anhydrides, by definition, both functional groups of compound (e1) are carboxylic acid groups. Thus, in view of the preferred bifunctional character of compound (e1) mentioned above, in the case of cyclic carboxylic anhydrides, the anhydride is considered to have two functional groups, i.e., two carboxylic acid groups.

[0054] Thus, in this preferred embodiment, the second compound (e2) comprises a polyalkylene group and a functional group reactive with a carboxy group. Hydroxyl groups are preferred, which means that the reaction proceeds as an esterification. Thus, preferred compounds (e2) are the poly(alkylene glycol) alkyl ethers described above. Of course, the preferences defined above with respect to the polyoxyalkylene units also apply in the context of these compounds (e2).

[0055] Even though this second explicit embodiment allows the formation of suitable reaction products (P), these products are not as good as the products prepared via compounds (e), especially compounds (e) having one isocyanate group, due to their relatively high polydispersity.

[0056] The equivalent ratio of the hydroxyl groups of the core compound to the functional groups reactive with the hydroxyl groups of the compound (e) or (e1) is 2 to 14 equivalents per functional group reactive with the hydroxyl groups.

[0057] As described above, the equivalent ratio between the hydroxyl groups of the core compound and the carboxylic acid groups of the aromatic or araliphatic carboxylic acid (d) is 1.5 to 3.5 equivalents of hydroxyl groups per carboxylic acid group.

[0058] In both above equivalence ratios, reference is made to the amount of hydroxyl groups of the original unreacted core compound. It is therefore clear that the amount of carboxylic acid groups of compound (c) and reactive groups of compounds (e) or (e1) preferably does not exceed the amount of hydroxyl groups of the core compound (since unreacted compounds (d) and / or (e) and / or (e1) will be present in the reaction mixture).

[0059] In general, it is possible to react core compound (c) with compounds (e) or (e1) and (e2) before or simultaneously with compound (d), however, it is preferred to (i) react compounds (c) and (d) first and then (ii) react the intermediate resulting from step (i) with compounds (e) or (e1) and (e2).

[0060] The process described above results in a reaction product (P).

[0061] In a preferred embodiment of the invention, the reaction product also contains carboxylic acid groups in the shell moiety covalently attached to the core moiety through units that contain functional groups that are reactive with hydroxy groups. These groups aid in anionic stabilization in aqueous media.

[0062] Thus, the carboxylic acid group is introduced via a group reactive with the carboxylic acid group and the hydroxyl group, for example a compound containing (further) a carboxylic acid group. Such compounds are also named compounds (f). Cyclic carboxylic anhydrides serve as such compounds (f), which means that these anhydrides are formally considered as compounds with two carboxylic acid groups for the reasons already outlined above. In fact, such cyclic carboxylic anhydrides are particularly preferred compounds (f). The reason is that, in principle, as already mentioned, due to the formally unequal reactivity of the two carboxylic acid groups, reaction conditions can be selected that allow the anhydride to be easily added via ring-opening addition to the core moiety without any or at least negligible reaction of the free carboxylic acid groups generated (i.e., no or at least negligible cross-linking of the two core molecules occurs, but the free carboxylic acid group remains for anion stabilization). Examples and preferred versions of such cyclic carboxylic anhydrides are already mentioned above.

[0063] As mentioned above, compound (e1), preferably a cyclic carboxylic anhydride, may be applied during the preparation of the reaction product. In this case, compounds (e1) and (f) are preferably the same, meaning that the addition of carboxylic acid groups described here is preferably carried out within the step of adding compound (e1). As a result, the amounts of compounds (e1) and (e2) in this case are in any case equal to the amount of (e1) being greater than (e2), which means that residual free carboxyl groups remain.

[0064] In the case of reaction products formed via compound (e), the addition of the carboxylic acid group obviously takes place in a separate step, namely by reaction of the hydroxyl group of the core with compound (f). Even though the reaction with compound (f) can generally take place in a different stage and / or simultaneously with the other reactions mentioned above, it has proven advantageous to carry out this reaction after the above-mentioned reaction of the core or the respective intermediate with compounds (d) and (e).

[0065] The acid value of the reaction product (P) is preferably 10 to 60 mg KOH / g (based on the reaction product (P) itself, i.e., excluding potential solvents for dispersing or dissolving the reaction product (P), the amount of reaction product (P) in the dispersion or solution being determined via the non-volatile content).

[0066] The amount of reaction product (P) is preferably 1 to 20% by weight, preferably 2.5 to 12.5% ​​by weight, in each case based on the total weight of the pigment paste (again, based on the reaction product (P) itself, this principle applying within the present application for any and all further specifications regarding amounts or properties, unless expressly stated otherwise).

[0067] The second essential component of the pigment paste is an organic pigment. This pigment can be selected and varied from a wide range of pigments known by those skilled in the art, such as azo pigments (e.g. monoazo, disazo, β-naphthol, benzimidazolone, condensation, metal complex, isoindolinone, isoindoline) and polycyclic pigments (phthalocyanine, quinacridone, perylene, perinone, diketopyrrolopyrrole, thioindigo, anthraquinone (indanthrone, anthrapyrimidine, flavanthrone, pyranthrone, anthanthrone, dioxazine, triarylcarbonium, quinophthalone)). In terms of color, pigments such as metallized and non-metallized azo red, quinacridone red and violet, perylene red, copper phthalocyanine blue and green, carbazole violet, monoarylide and diarylide yellow, benzimidazolone yellow, tolyl orange, naphthol orange, etc. can be mentioned.

[0068] As is generally known and already outlined above, a pigment paste is a formulation of a pigment in a carrier material (also called paste resin or paste binder), i.e. an organic resin material in which the pigment is dispersed and present in a higher concentration than in the subsequent use. The latter use is generally in the manufacture of a coating composition. More specifically, in such a pigment paste, the weight ratio of pigment to polymer is generally higher than in the coating composition in which the paste is used. Water and / or organic solvents are generally present as well as a carrier material (different polymer, also called paste binder). Different additives such as wetting agents can also be used.

[0069] As already mentioned, the use of pigment pastes in the coating industry significantly facilitates the technically complex process of pigment dispersion. For example, dust-free handling of the pigment is guaranteed when formulating the coating material. Furthermore, the pigments in the paste are optimally wetted and very well dispersed, so that an improved distribution is also obtained in the coating material. This of course results in improved performance properties of the coating material and the coating system produced therefrom, such as a particularly homogeneous color or color distribution in the coating system. In the sense of the present invention, the reaction product (P) quite obviously serves as a carrier material (paste binder) for providing finely distributed and stably dispersed organic pigments.

[0070] The preparation of the pigment paste thus requires contacting the reaction product (P) with an organic pigment under high shear sufficient to disperse the pigment, i.e. to wet the surface of the pigment particles with the dispersing resin (P). As is generally known, the shear introduced by this grinding process thereby breaks down the pigment agglomerates to smaller particle sizes and ultimately to the primary pigment particles. The breakage of the agglomerates and the wetting of the primary pigment particles are important for the stability and color development of the pigment. The pigment may be utilized in an amount typically of, for example, 2 to 40% by weight, preferably not more than 5 to 15% by weight, in each case based on the total weight of the pigment paste. The amount of pigment used depends on the nature of the pigment, the depth of color and / or the intensity of the intended effect, and the dispersibility of the pigment.

[0071] The dispersant to pigment ratio in the pigment paste (also referred to as the reaction product (P) to pigment ratio) is preferably at least 0.2, preferably at least 0.5, more preferably at least 0.55 (in each case by weight). Preferred ranges are 0.2 to 1.5, more preferably 0.5 to 0.8, and even more preferably 0.55 to 0.75.

[0072] The present invention also provides a method for producing a pigment paste comprising the reaction product (P) and an organic pigment.

[0073] According to the above outline, the method for producing a pigment paste comprises the steps of (1) contacting the reaction product (P) with an organic pigment, preferably in the presence of water, an organic solvent and optionally additives such as wetting agents, to obtain a respective mixture, and (2) exposing the mixture from step (1) to a shear force. Applicable organic solvents are, for example, propylene glycol n-butyl ether, Dowanol PnB, ethylene glycol n-butyl ether and / or butyl cellosolve.

[0074] Specifically, step (1) of producing the pigment paste is preferably carried out by: (1a) preparing a dispersion containing the reaction product (P), water, an organic solvent and optionally additives; and (1b) mixing the dispersion of step (1a) with an organic pigment.

[0075] Step (2), i.e. subjecting the mixture of step (1) to shear forces to effectively disperse and reduce the particle size of the pigment, is preferably carried out by grinding. Respective grinding equipment, such as high-energy mills, and respective procedures are known and can be selected depending on the individual case. The grinding process is preferably carried out by applying grinding beads, which are known, for example for a period of 1 to 20 hours. Such beads generally have a particle size, for example, of about 0.1 to 10 mm (diameter). The grinding process may also be carried out in different grinding steps, differing, for example, in bead size, mass ratio of mixture to beads, and / or grinding duration. After grinding, the prepared dispersion is separated from the grinding beads, in particular by filtration, resulting in a pigment paste according to the invention.

[0076] The weight ratios of the individual constituents of the pigment paste are, for example, 1-20% by weight of reaction product (P), 2-40% by weight of organic pigment, 40-90% by weight of water and 2-20% by weight of organic solvent in each case relative to the total weight of the pigment paste.

[0077] The pigment pastes prepared by the method according to the invention are characterized by outstanding pigment particle size characteristics (i.e. relatively small particle size) and fine distribution of the pigments, and thus good dispersion behavior and stability, as confirmed, for example, by low scattering determined via the brightness of the cured coating layer, as shown in the Examples section below.

[0078] The amount of pigment paste in the coating composition of the invention is selected according to the individual needs and requirements and may be as low as 0.1% by weight (for example in tinted clear coating compositions) or as high as 25% by weight. A preferred range is therefore 0.1-25% by weight relative to the total weight of the coating composition. Even more preferably, the range is 2.5-15% by weight, preferably 3.5-10% by weight, in each case relative to the total weight of the coating composition.

[0079] Coating compositions according to the present invention may further comprise components known and commonly used in coating compositions.

[0080] The coating composition may include other resins or polymers. Examples of resins or polymers include (meth)acrylate polymers (also known as acrylic polymers or resins), polyesters, polyethers, and / or polyurethanes. The other resins or polymers may have functionality that reacts with crosslinkers that may be included in the coating composition for the other resins or polymers. In certain preferred embodiments, the coating composition includes additional resins or polymers that have hydroxyl groups, carbamate groups, or combinations of such groups. In various embodiments, the coating composition includes hydroxyl-functional acrylic polymers, hydroxyl-functional polyesters, and / or hydroxyl-functional polyurethanes. Polysiloxane polyols may be included. These polymers are well known to those skilled in the art and are widely used as binder polymers in coating compositions. Nevertheless, the following paragraphs will describe such components in more detail (with more detailed and even deviant nomenclature, where appropriate).

[0081] Polyvinyl polyols, such as acrylic (polyacrylate) polyol polymers, may be used as hydroxy-functional materials. The acrylic or polyacrylate polymers may be copolymers of both acrylic and methacrylic monomers with other copolymerizable vinyl monomers. The term "(meth)acrylate" is used for convenience to represent either or both of the acrylate and methacrylate, and the term "(meth)acrylic" is used for convenience to represent either or both of the acrylic and methacrylic.

[0082] The polyester polyols may be prepared by reacting (a) a polycarboxylic acid or an esterifiable derivative thereof with a monocarboxylic acid, if desired, (b) a polyol with a monofunctional alcohol, if desired, and (c) other modifying components, if desired. Examples of polycarboxylic acids and their esterifiable derivatives include, but are not limited to, phthalic acid, isophthalic acid, terephthalic acid, halophthalic acids, such as tetrachloro- or tetrabromophthalic acid, adipic acid, glutaric acid, azelaic acid, sebacic acid, fumaric acid, maleic acid, trimellitic acid, pyromellitic acid, tetrahydrophthalic acid, hexahydrophthalic acid, 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexane-dicarboxylic acid, 4-methylhexahydrophthalic acid, endomethylenetetrahydrophthalic acid, tricyclodecanedicarboxylic acid, endethylenehexahydrophthalic acid, camphoric acid, cyclohexanetetracarboxylic acid, and cyclobutanetetracarboxylic acid. The alicyclic polycarboxylic acids can be used either in their cis or trans form or as a mixture of the two forms. Esterifiable derivatives of these polycarboxylic acids include their single or multiple esters with aliphatic alcohols having 1 to 4 carbon atoms or hydroxy alcohols having 4 or less carbon atoms, preferably methyl esters and ethyl esters, and anhydrides of these polycarboxylic acids, if present. Examples of suitable monocarboxylic acids that can be used together with the polycarboxylic acids include, but are not limited to, benzoic acid, tert-butylbenzoic acid, lauric acid, isononanoic acid, and fatty acids of naturally occurring oils.Examples of suitable polyols include, but are not limited to, any of those already mentioned above, such as ethylene glycol, butylene glycol, neopentyl glycol, propanediol, butanediol, hexanediol, diethylene glycol, cyclohexanediol, cyclohexanedimethanol, trimethylpentanediol, ethylbutylpropanediol, ditrimethylolpropane, trimethylolethane, trimethylolpropane, glycerol, pentaerythritol, dipentaerythritol, tris-hydroxyethyl isocyanate, polyethylene glycol, polypropylene glycol, and polyols derived from natural oils. Examples of monoalcohols that may be used together with the polyols include, but are not limited to, butanol, octanol, lauryl alcohol, and ethoxylated and propoxylated phenols. Examples of suitable modifying components include compounds that contain groups reactive to the functional groups of the polyester, including, but are not limited to, polyisocyanates and / or diepoxide compounds, and, if desired, monoisocyanates and / or monoepoxide compounds. Polyester polymerization may be carried out by known standard methods. The reaction is conventionally carried out at temperatures between 180° C. and 280° C., if desired, in the presence of a suitable esterification catalyst. Typical catalysts for esterification polymerization are protonic acids, Lewis acids, titanium alkoxides, and dialkyltin oxides, such as lithium octanoate, dibutyltin oxide, dibutyltin dilaurate, para-toluenesulfonic acid, under reflux with a small amount of a suitable solvent as an entraining agent, such as an aromatic hydrocarbon, e.g., xylene, or a (cyclo)aliphatic hydrocarbon, e.g., cyclohexane.

[0083] Hydroxyl-functional polyurethanes may also be used in the coating composition with aryl-modified highly branched polyols. Examples of suitable polyurethane polyols include polyester-polyurethanes, polyether-polyurethanes, and polycarbonate-polyurethanes, including but not limited to polyurethanes polymerized using polyether and polyester polymeric diol reactants, including polycaprolactone polyester or polycarbonate diols. These polymeric diol-based polyurethanes are prepared by the reaction of a polymeric diol (polyester diol, polyether diol, polycaprolactone diol, polytetrahydrofuran diol, or polycarbonate diol), one or more polyisocyanates, and, optionally, one or more chain-extending compounds. The term chain-extending compound refers to compounds having two or more functional groups, preferably two functional groups, reactive with isocyanate groups, such as diols, amino alcohols, and diamines. Preferably, the polymeric diol-based polyurethanes are substantially linear (i.e., substantially all reactants are difunctional).

[0084] Polysiloxane polyols can be prepared by hydrosilylation of silicon hydride-containing polysiloxanes with alkenyl polyoxyalkylene alcohols containing two or three terminal primary hydroxyl groups, for example, allyl polyoxyalkylene alcohols such as trimethylolpropane monoallyl ether and pentaerythritol monoallyl ether.

[0085] Any of the above polyol resins and polymers can be derivatized to contain carbamate groups according to known methods, for example, by reaction of a hydroxyl-functional material with an alkyl carbamate, such as methyl carbamate or butyl carbamate, by a reaction referred to as "transcarbamation" or "transcarbamoylation." In another method of forming carbamate-functional resins and polymers for use in coating compositions, the resins and polymers can be polymerized using carbamate-functional monomers.

[0086] The coating composition of the present invention may contain at least one crosslinking or curing agent that is reactive with hydroxyl groups, such as aminoplast crosslinking agents having active methylol, methylalkoxy, or butylalkoxy groups; polyisocyanate crosslinking agents that may have blocked or unblocked isocyanate groups; polyanhydrides; and polyepoxide-functional crosslinking or curing agents that may be reactive with the carboxylic acid groups of the hydroxyl and aryl modified hyperbranched polyols. Aminoplast crosslinking agents are preferred.

[0087] The coating composition may further comprise solvents, further pigments, fillers or customary additives, however, coating compositions which do not contain any pigments other than those contained in the pigment paste described above are preferred.

[0088] The ratio of pigment (or pigment solids) to total solids of the coating composition may vary according to individual needs and also depends on the nature of the pigment, the depth of colour and / or the intensity of the effect to be produced, and the dispersibility of the pigment, however, a preferred range for this ratio is 0.05 to 0.35, more preferably 0.05 to 0.2, even more preferably 0.075 to 0.15 (in each case by weight).

[0089] A potential field of application of the coating composition of the present invention is a transparent pigmented topcoat (or tinted clearcoat), i.e. a composition that is meant to represent and is therefore arranged as the top layer of a multilayer assembly. In a preferred embodiment, however, the coating composition of the present invention is a basecoat composition, preferably a water-based basecoat composition, i.e. a composition that is meant to represent and is therefore arranged as a color-imparting intermediate coating material, for example used in automotive finishing and general industrial painting. The basecoat material is generally applied to a substrate that has been pretreated with a primer-surfacer and / or a further basecoat that is located under the basecoat of the present invention. The substrates used may also include existing coating systems, which may also optionally require pretreatment (for example by sanding). In order to protect the basecoat film, especially from environmental influences, at least one additional clearcoat film is generally applied thereon. This is generally done in a wet-on-wet process, i.e. the clearcoat material is applied while the basecoat film is not cured. It is then finally cured together with the clearcoat.

[0090] The present invention relates to a method of producing a coating layer on a substrate by applying a coating composition of the present invention to the substrate, forming a film from the applied coating composition, and curing the applied coating composition to obtain a cured coating layer.

[0091] The coating composition can be coated by any of a number of techniques well known in the art. These techniques include, for example, spray coating, dip coating, roll coating, curtain coating, knife coating, painting, pouring, dipping, impregnating, trickling or rolling, etc. Spray coating is typically used for automotive body panels. It is preferred to use spray application methods such as compressed air spray, airless spray, high speed rotary, electrostatic spray application, alone or in combination with thermal spray application such as hot air spray.

[0092] The coating compositions described herein are particularly used in the technically and aesthetically particularly demanding field of automotive OEM finishing and also automotive refinishing. The coating compositions can be used in both single-stage and multi-stage coating methods. Thus, the present invention also provides a multi-coat coating system comprising at least one pigmented basecoat film based on the coating composition of the present invention and optionally having at least one clearcoat disposed thereon.

[0093] The applied coating composition is usually cured after a certain rest time or "flash" period. The rest time serves, for example, to level the coating film and remove volatiles or to evaporate volatile components such as solvents. The rest time can be assisted or shortened by application of elevated temperature or by reduced humidity, provided that this does not leave any damage or alteration to the coating film, such as, for example, unfinished crosslinking. The thermal curing of the coating composition is not modified in terms of method, but instead is carried out by typical known methods, such as heating in a forced air oven or irradiation with IR lamps. Thermal curing can also be carried out in several stages. Another preferred curing method is curing by near infrared (NIR) radiation. Various methods of curing can be used, but thermal curing is preferred. Generally, thermal curing is carried out by exposing the coated article to elevated temperatures, provided primarily by a heat source of radiation. After application, the applied coating layer is cured with heat at temperatures of 30-200°C, or 40-190°C, or 50-180°C for times of 1 minute to 10 hours, more preferably 2 minutes to 5 hours, and especially 3 minutes to 3 hours, although longer curing times can be used for temperatures used for automotive refinishing, preferably between 30-90°C. The coating composition of the present invention can be used both for refinish coatings and for original finish coatings that are cured at higher temperatures. A typical method for applying the refinish coating composition includes application and drying with curing at room temperature or at an elevated temperature between 30-90°C. OEM coatings are typically cured at higher temperatures, for example, about 110 to about 135°C. Curing times will vary depending on the particular components used and physical parameters such as layer thickness, but typical curing times are about 15 to about 60 minutes, and preferably about 15 to 25 minutes for blocked acid catalyzed systems and about 10 to 20 minutes for unblocked acid catalyzed systems.In the case of a multi-coat coating system comprising at least one pigmented basecoat film based on the coating composition of the present invention and at least one clearcoat disposed thereon, the curing is preferably carried out together, i.e. the basecoat and the clearcoat are applied wet-on-wet and then cured in one final curing step.

[0094] The cured basecoat layer formed can have a thickness of about 5 to about 75 micrometers, depending primarily on the color desired and the thickness required to form a continuous layer that provides that color. The cured clearcoat layer formed typically has a thickness of about 30 to about 65 micrometers.

[0095] The coating compositions can be applied to many different types of substrates, including metallic substrates such as bare steel, phosphated steel, galvanized steel, or aluminum, and non-metallic substrates such as plastics and composites. The substrate may be any of these materials that already has a layer of another coating thereon, such as a layer of a cured or uncured electrocoated primer, primer surfacer, and / or basecoat.

[0096] The substrate may be first primed with an electrodeposition (electrocoat) primer. The electrodeposition composition may be any electrodeposition composition used in automotive vehicle coating operations. Examples of electrocoat compositions include, but are not limited to, electrocoat compositions sold by BASF. Electrodeposition coating baths typically include an aqueous dispersion or emulsion containing a primary film-forming epoxy resin with ionic stabilization (e.g., salt-forming amine groups) in water or a mixture of water and an organic co-solvent. A crosslinker capable of reacting with the functional groups of the primary resin under suitable conditions, such as the application of heat, is emulsified with the primary film-forming resin, thereby curing the coating. Suitable examples of crosslinkers include, but are not limited to, blocked polyisocyanates. Electrodeposition coating compositions typically include one or more pigments, catalysts, plasticizers, fusing aids, defoamers, flow control agents, wetting agents, surfactants, UV absorbers, HALS compounds, antioxidants, and other additives.

[0097] The electrodeposition coating composition is preferably applied to a dry film thickness of 10 to 35 μm. After application, the coated vehicle body is removed from the bath and rinsed with deionized water. The coating may be cured under suitable conditions, for example, by baking at about 135° C. to about 190° C. for about 15 to about 60 minutes.

[0098] Finally, the present invention relates to a cured coating layer, preferably a cured multi-layer coating system, prepared according to the above-described method, in which the coating composition of the present invention is applied as a basecoat composition, in which the basecoat composition allows optimal color properties, such as high transparency (low scattering) and excellent color depth in particular. EXAMPLES

[0099] Measurement method: 1. Determination of the Nonvolatile Fraction The amount of solids content (non-volatile content, non-volatile content, solid fraction, etc.), including the total solids content, was determined via DIN EN ISO3251:2019-09 at 110°C for 60 min.

[0100] 2. Color value (L * , a * , b * ) 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 recognizable color in the color space is represented by a 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 the lower the number the more bluish the color. * The axis is perpendicular to this plane and represents brightness (luminosity). * The axis has endpoints black (L=0) and white (L=100). Lower values ​​therefore indicate darker colors. The color value L of the coating substrate (after curing) * , a * and b *is determined after preparation, including curing, according to ASTM E 284-81a. The values ​​are measured with the aid of a BYK-mac i (BYK-Gardner). The analysis of the cured samples is carried out according to the instrument BYK-mac i spectrophotometer standard operating procedure 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 illuminant, recording data for each angle using the CIELab settings. The measurements are made on individual panels at different positions and the values ​​are reported as an average of the trials. The color values ​​L reported in the experimental part below * , a * , b * is for an angle of 110°.

[0101] Within this application, this method was used because larger particle size of the pigment aggregates results in more scattered light, which increases the measured lightness of the cured coating film. The 110° angle is the most sensitive to detect increased scattering because it has the longest film path length. Therefore, the L value (lightness) at the 110° angle was used for evaluation, with dispersions that produce lower values ​​being more transparent and better.

[0102] As a rule, L110° values ​​above 3.5 reflect a lightness that corresponds to unacceptable pigment distribution and therefore unacceptable transparency. Values ​​below 3.0 are rated as good, while values ​​below 2.5 reflect excellent pigment distribution / dispersion and therefore transparency.

[0103] 1. Synthesis of reaction product (P) The following sections 1.1.-1.2 are detailed synthesis protocols for two types of reaction products (P) used according to the present invention. The synthesis protocols for these types of reaction products (P) are examples of reaction products (P) shown in Table 1. That is, the overall and basic reaction conditions of the reaction were adapted correspondingly, if necessary or appropriate, to the specifications regarding educts and molar amounts. Furthermore, the details of the actually selected educts and molar amounts are shown in Table 1.

[0104] 1.1 Type 1 reaction products (P) Tripentaerythritol (compound (cI)), 2-naphthoxyacetic acid (compound (d)), DBTO (catalyst, 0.1% by weight) and xylene (3.5% by weight) were charged to a reactor and heated to 230° C., then reacted at above 200° C. for 2 hours, with the water produced being continuously removed. After this reaction time, the remaining water and xylene were removed, the mixture was cooled to 140° C., and 3-ethoxypropionate ethyl (EEP) (26.4% by weight) and n-butyl acetate (10.8% by weight) were added.

[0105] In a separate reaction step, poly(ethylene glycol) methyl ether and isophorone diisocyanate (IPDI) were reacted in equimolar amounts to obtain compound (e). Thereby, poly(ethylene glycol) methyl ether (MPEG2000) was charged to a reactor and heated to 110°C (-200mmHG vacuum) to melt and remove entrained water (60-90 min). After that, the reactor was cooled to 60°C and the vacuum was discontinued. Then, in a first step, isophorone diisocyanate was directly charged as quickly as possible, followed by the addition of dibutyl dilaurate (0.1 wt%), thereby maintaining the temperature below 70°C. After a reaction time of 2-3 hours at 65°C, the reaction mixture was cooled and the monoisocyanate-functional compound (e) was isolated.

[0106] In the third reaction step, compound (e) and the reaction product of compounds (cI) and (d) were heated to 75° C. with 0.06% by weight of dibutyltin dilaurate and treated for 1-3 hours until all NCO had reacted. The reactor was then heated to 120° C. and a charge of succinic anhydride (compound (f)) and EEP (1.3% by weight) was added. After a treatment time of 2-5 hours at 145° C., the mixture was cooled to 60° C. A charge of 0.768% by weight of EEP and 0.3% by weight of n-butyl acetate was then added. Finally, the non-volatile content was adjusted with 2-butoxyethanol, which in most cases made a content of about 60% appropriate.

[0107] 1.2 Type 2 reaction products (P) Again, tripentaerythritol (compound (cI)), 2-naphthoxyacetic acid (compound (d)), DBTO (catalyst, 0.1% by weight) and xylene (3.5% by weight) were charged to a reactor and heated to 230° C., then reacted at above 200° C. for 2 hours, with continuous removal of the water produced. After this reaction period, the remaining water and xylene were removed, the mixture was cooled to 140° C., and 3-ethoxypropionate ethyl (EEP) (26.4% by weight) and n-butyl acetate (10.8% by weight) were added.

[0108] In the second reaction step, the reaction product of compounds (cI) and (d) was charged into a reactor, and succinic anhydride (compound (e1)) and EEP (1.1% by mass) were added. The reaction mixture was heated at 145°C for 2 to 5 hours to obtain an intermediate.

[0109] Finally, the aforementioned intermediate and poly(ethylene glycol) methyl ether (MPEG2000, compound (e2)) were heated to a temperature of 230° C. in a reactor together with 0.11% by weight of DBTO and 3.5% by weight of xylene. The mixture was then treated above 200° C. for 6-7 hours to continuously remove the water produced. After this reaction time, the residual water and xylene were removed, the mixture was cooled to 140° C., and EEP (1.0% by weight) and n-butyl acetate (0.4% by weight) were added. Finally, the non-volatile content was adjusted, if appropriate, by adding 2-butoxyethanol.

[0110] 1.3 Notes: The following Table 1 shows the reaction product (P) prepared by using, instead of the above products of compounds (cI) and (d), a product prepared by first reacting dipentaerythritol and adipic acid in a molar ratio of 2:1 by a standard esterification reaction to obtain compound (cII), which formally and on average contains 10 hydroxyl groups per molecule, and which was correspondingly applied in the further reaction process.

[0111] 1.4 Produced reaction product (P) Table 1 shows a list of the reaction products.

[0112] Thus, the set molar ratio w / x / y / z represents the set ratio of "hydroxyl group (w) of the core portion (compound (cI) or (cII)) / carboxy functional group (x) of compound (d) / NCO functional group (y) of compound (e) / reactive carboxyl side chain (z) of anhydrous compound (f)" for the reaction product of type 1.

[0113] For the reaction products of type 2, the set ratio q / r / s / t represents "hydroxyl group (q) of the core part (compound (cI) or (cII)) / carboxy functional group (r) of compound (d) / carboxyl side chain (s) of anhydrous compound (e1) reacting with the hydroxyl group of the core / hydroxyl group (t) of compound (e2) reacting with the carboxyl side chain of ring-opened anhydrous compound (e1)."

[0114] As a comparative reaction product (CP), a known pigment dispersant additive containing polyalkylene oxide units (in the form of reacted MPEG 2000) was applied. The applied dispersant consisted of 35.5% by weight resin solids (non-volatile) and 64.5% by weight solvent. The solvent content of the dispersant was as follows: 28.4% by weight propylene glycol n-propyl ether, 6.1% by weight methyl isoamyl ketone (MIAK), 28.5% by weight deionized water and 1.5% by weight mineral spirits. The resin present in the dispersant was prepared as disclosed in Example 5 of U.S. Pat. No. 5,270,399.

[0115] [Table 1]

[0116] 2. Preparation of pigment paste and coating composition 2.1 Pigment paste The pigment pastes were prepared using the following general procedure: A given pigment is weighed into a bottle. A given reaction product (P) as a dispersant is then added to a separate container to reach the given dispersant level on the pigment. The reaction product is then slowly diluted in water with stirring. Once completely dissolved, propylene glycol n-butyl ether (Dowanol PnB) is added dropwise with stirring to obtain a clear solution. The reaction product dispersion is then mixed with the pigment with stirring to create a consistent pre-paste formulation / suspension. A milling step is then performed, if necessary. In any case, micro-milling (grinding) was performed.

[0117] Blue pigment paste: For the blue pigment paste, Palomar Blue 248-4806, Blue 15:1 (Sun Chemical Co.) was applied. 10 parts by weight of the pigment was added to a stirred mixture of propylene glycol n-butyl ether (Dowanol PnB) and a specific reaction product as a dispersant containing water. The resulting suspension was stirred for 5 minutes using a Cowles blade. The pH was adjusted to 8.0 using a 20% aqueous solution of DMEOA as measured with a Starter 300 pH Portable pH meter (Ohaus Corporation, Parsippany, New Jersey, USA). The pigment suspension was transferred to an 8 oz mixing jar (Qorpak) and 0.3-0.4 mm YTZ grinding media (Fox Industries) in a 2:1 ratio and stirred for 10 hours using a LAU shaker (LAU disperser DAS200-LAU GmbH Co.). The resulting paste was separated from the 0.3-0.4 mm YTZ media by gravity filtration and used without further modification in the coating composition.

[0118] Black pigment paste: Paliogen Black L0086 was applied for the black pigment paste. Again, 10 parts by weight of the pigment was added to a stirred mixture of propylene glycol n-butyl ether (Dowanol PnB) or Dowanol PnP and the specific reaction product as a dispersant containing water. The resulting suspension was stirred for 5 minutes using a Cowles blade. The pH was adjusted to 8.1 using 20% ​​DMEOA in water, as measured with a Starter 300 pH Portable pH meter (Ohaus Corporation, Parsippany, New Jersey, USA). The pigment suspension was transferred to an 8 oz mixing jar (Qorpak) and 0.9-1.1 mm YTZ grinding media (Fox Industries) and stirred for 4 hours during the grinding process using a LAU shaker (LAU Disperser DAS200-LAU GmbH). The 0.9-1.1 mm YTZ media was separated by gravity filtration. The paste thus recovered was transferred to an 8 oz mixing jar (Qorpak), doused with 0.3-0.4 mm YTZ grinding media at a bead to paste ratio of 2:1, and agitated and milled for 12 hours using a LAU shaker (LAU disperser DAS200 - LAU GmbH). The resulting final paste product was filtered to remove 0.3-0.4 mm of solvent and used in the coating composition without further modification.

[0119] Tables 2 and 3 provide details of the pigment pastes. All amounts refer to weight. For components available as dispersions / solutions and therefore containing solvent, the amount refers to the component as applied (i.e. including solvent) and the dispersant to pigment ratio refers to dispersant (effective amount excluding solvent) and pigment only.

[0120] 2.2. Coating Composition The compositions were prepared by adding the above pigment paste to an unpigmented one-part composition intermediate, then adjusting the solids content with a polyurethane resin component, adjusting the pH to 8.1 with N-N-dimethylethanolamine (20% in water) and adding water to adjust to the target pigment concentration. The unpigmented intermediate was of water-based type and contained, among other components, Laponite (Fa.BYK) as a rheology modifier and polyurethane, acrylic resin and polyester as binder components. Additionally, a melamine resin (Cymel 327, Fa Allnex) was included as a crosslinker component.

[0121] This allowed the preparation of coating compositions of the present invention, in this case transparent blue or black basecoat compositions.

[0122] Further details of the coating compositions are provided in Tables 2 and 3. All amounts refer to weight. For components available as a dispersion / solution and therefore including solvent, the amount refers to the component as applied (i.e. including solvent) and the dispersant to pigment ratio refers to dispersant (effective amount excluding solvent) and pigment only.

[0123] 3. Preparation and Evaluation of Cured Coatings 3.1 Application of a Blue Pigmented Transparent Basecoat Composition The compositions were applied as thin films onto Melinex drawdown sheets (Puetz GmbH+C0.Folien KG, Taunusstein, Germany) using a 100 micrometer gap on a Byk drawdown bar. The wet clear basecoat films were flashed for 15 minutes under ambient conditions and then baked at 130°C for 25 minutes.

[0124] The cured coating on the Melinex substrate was then analyzed with a Byk Mac i spectrophotometer. Samples were placed on a mirror with the coating facing the mirror side and the Melinex side facing the Byk Mac i instrument. Samples were illuminated with d65 light at 110 degrees off specular using CIELab settings. The resulting coating was sampled at least five times in different areas of the coating film.

[0125] 3.2 Application of Straight Shade Basecoat Compositions Containing Black Pigments The compositions were applied to steel panels (T12M black and white panels, Leneta) using a 200 micrometer gap on a Byk drawdown bar. The panels and their coatings were flashed for 10 minutes at 40° C. The panels were then spray coated with a commercial clearcoat composition (ProGloss® 2K4, Coatings Division, BASF Corporation, USA) and baked for 25 minutes at 130° C.

[0126] The cured coatings on the steel substrates were then analyzed with a Byk Mac i spectrophotometer. Samples were placed on a mirror with the coating facing the mirror side and the Melinex side facing the Byk Mac i instrument. Samples were illuminated with d65 light at 110 degrees off specular using CIELab settings. Sampling of the resulting coating was done at least five times in different areas of the coating film.

[0127] Tables 2 and 3 show the results of cured and multi-layer coatings produced based on the coating compositions of the present invention and comparative coating compositions, respectively.

[0128] Table 2 clearly shows that the coatings of the invention show at least acceptable, but often good or excellent transparency and therefore pigment distribution, whereas the comparative systems in this respect are unacceptable. For the black compositions and coatings, the systems of the invention show a significant reduction in the L(110°) values ​​of the cured coatings compared to the comparative systems.

[0129] Overall, the data shows that the dispersing ability of the reaction product / dispersant used in this invention is significantly superior to the comparative dispersant (CP).

[0130] [Table 2]

[0131] [Table 3]

[0132] [Table 4]

[0133] [Table 5]

Claims

1. 1. A coating composition comprising a pigment paste, the pigment paste comprising an organic pigment and an aryl modified branched reaction product (P), the reaction product (P) being in reacted form: (a) a polyhydroxy-functional core moiety, and (b) a shell portion comprising polyalkylene oxide units and aromatic units; wherein the polyalkylene oxide units and aromatic units are covalently bonded to the core moiety through units that include functional groups that are reactive with hydroxy groups.

2. 10. The coating composition of claim 1, wherein the shell portion further comprises an acid group covalently bonded to the core portion via a unit that includes a functional group that is reactive with a hydroxy group.

3. 3. The coating composition according to claim 1, wherein the functional group reactive with a hydroxy group is selected from a carboxyl group, a cyclic carboxylic acid anhydride group, and an isocyanate group.

4. 4. The coating composition of claim 1, wherein the aromatic units are added via reaction of hydroxyl groups of the core moiety with at least one aromatic or araliphatic carboxylic acid.

5. 5. The coating composition of claim 1, wherein the polyalkylene oxide units are added via reaction of hydroxyl groups of the core portion with at least one component (e) having polyalkylene oxide units and isocyanate groups.

6. 6. The coating composition according to claim 1, wherein the polyalkylene oxide units are polypropylene oxide and / or polyethylene oxide and mixed copolymers thereof.

7. 7. The coating composition according to claim 1, wherein the reaction product (P) has an acid value of 10 to 60 mg KOH / g.

8. 8. Coating composition according to claim 1, wherein the mass ratio of reaction product (P) to the organic pigment in the pigment paste is at least 0.

55.

9. 9. Coating composition according to any one of claims 1 to 8, wherein the pigment paste comprises 1 to 20% by weight of reaction product (P), 2 to 40% by weight of an organic pigment, 40 to 90% by weight of water and 2 to 20% by weight of an organic solvent, the weight percentages being in each case relative to the total weight of the composition.

10. 10. The coating composition according to any one of claims 1 to 9, wherein the ratio of pigment (or pigment solids) to total solids of the coating composition is from 0.05 to 0.

2.

11. 11. The coating composition of claim 1, wherein the coating composition comprises a hydroxyl-functional acrylic polymer, a hydroxyl-functional polyester, and / or a hydroxyl-functional polyurethane.

12. 12. The coating composition of claim 1, wherein the coating composition is water-based.

13. 1. A method for producing a cured coating on a substrate, comprising the steps of: (i) applying the coating composition of any one of claims 1 to 12 onto a substrate; (ii) forming a film from the applied coating composition; and (iii) curing the film applied according to step (ii). The method includes:

14. - between steps (ii) and (iii), applying a clearcoat composition to the film according to step (ii); and - step (iii) also involves curing the applied clearcoat composition, i.e. both the basecoat and the clearcoat films are cured together to obtain a multi-layer coating; The method of claim 13.

15. A coating or multi-layer coating produced by the method of claims 13 and 14.

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