Coating compositions comprising pigment pastes containing organic pigments and aryl-modified branched reaction products

Abstract

This application relates to a coating composition comprising a pigment paste, wherein the pigment paste comprises an organic pigment and an aryl-modified branched reaction product (P) comprising, in a reactive form, a core structural portion (a) with polyhydroxy functional groups and a shell structural portion (b) comprising polyoxyethylene units and aromatic units, wherein the polyoxyethylene units and aromatic units are covalently linked to the core structural portion via units comprising functional groups reactive to hydroxyl groups. This application also relates to a method for producing a cured coating on a substrate using the aforementioned coating composition.

Description

[0001] This invention relates to coating compositions comprising special pigment pastes, namely pigment pastes containing organic pigments and special aryl-modified branched reaction products. The invention also relates to a method for producing the aforementioned coating compositions, particularly water-based coating compositions. Furthermore, the invention relates to coatings (coating layers) produced from the aforementioned compositions. The invention provides and allows for the fine distribution and stable integration of organic pigments with optimal and therefore small particle sizes in both the coating compositions and pigment pastes, thereby enabling coating layers to possess optimal color characteristics, particularly high transparency (low scattering) and high color concentration in multilayer coatings.

[0002] Background information and existing technology

[0003] This section provides information that helps in understanding the invention, but is not necessarily prior art. All references discussed below are incorporated herein by reference in their entirety.

[0004] For coating compositions, the pigments used to provide color must be reduced and stabilized at an optimal particle size, which varies with the pigment itself, thus allowing the coating to exhibit optimal color characteristics. When using certain organic pigments, to obtain optimal color characteristics, the particle size of the pigment must be reduced much more significantly compared to that used for typical inorganic pigments. The adsorption characteristics of organic pigments also differ, thus affecting color characteristics. Resins are typically used to promote the mechanical reduction of pigment particles and subsequent stabilization. Because the physical / chemical properties of organic pigments differ from those of inorganic pigments, and because the optimal particle size of organic pigments is much smaller, resins used to disperse inorganic pigments are not effective for preparing optimal organic pigment dispersions. Furthermore, resins specifically designed for dispersing organic pigments are expensive. These difficulties and challenges are even more pronounced in the case of aqueous coating compositions (i.e., compositions that contain not only or primarily organic solvents (also called solvents) as their dispersion medium, but also a significant portion of water as their dispersion medium).

[0005] US 2019 / 0106592 A1 describes an aryl-modified hyperbranched polyol applied in a first variant to a waterborne (i.e., aqueous) composition or in a second variant to a solvent-based composition. While systems containing water-sensitive pigments achieve storage stability and low VOCs even in waterborne compositions without the use of chromium compounds, this publication refers to solvent-based compositions containing small organic pigments that result in optimal color properties of the resulting coating layer.

[0006] US 2016 / 0017175 A1 describes a coating composition comprising a flexible hyperbranched polyol that can be prepared by: (a) reacting a polyol containing at least three hydroxyl groups with an aliphatic dicarboxylic acid having 6-36 carbon atoms or an esterifiable derivative thereof to form a hydroxyl-functionalized core; (b) reacting the core with a cyclic carboxylic anhydride to form a carboxylic acid-functionalized first intermediate; and (c) reacting the first intermediate with an epoxy-functionalized compound having an epoxide group to form a hyperbranched polyol. The coating composition can be cured into a coating layer with excellent flexibility.

[0007] U.S. Patent No. 6,646,049 discloses a base material for coating compositions comprising a combination of a primary resin polyol, a hyperbranched polyol as a reactive intermediate, and at least one crosslinking agent. The primary resin polyol is at least one of polyester polyol, polyether polyol, and polyacrylate. The hyperbranched polyester polyol can be used as a reactive diluent, which crosslinks with isocyanates, isocyanurates, epoxides, anhydrides, or their corresponding polyacids and / or amino plastics to form a base material with specific properties to help control the rheology of the coating system. The hyperbranched polyol, the primary resin polyol, or both optionally contain urethane functional groups. The coating composition can be prepared using this base material with additional components.

[0008] Problems and technical solutions

[0009] There remains a desire to improve coating compositions containing organic pigments in terms of optimal pigment particle size and dispersion behavior (including dispersion stability), thereby enabling the coating layer to exhibit optimal color properties. The coating composition should also be an economically viable alternative to compositions comprising a specialty resin specifically designed for dispersing organic pigments, and capable of stabilizing fine organic pigment particles more effectively than conventional dispersion resins.

[0010] The above-mentioned problem has been found to be solved by a coating composition comprising a pigment paste, wherein the pigment paste comprises an organic pigment and an aryl-modified branched reaction product (P) comprising, in a reactive form, the following components:

[0011] (a) The nuclear structural part with polyhydroxyl functionality, and

[0012] (b) A shell structure portion comprising polyoxyethylene units and aromatic units, wherein the polyoxyethylene units and aromatic units are covalently linked to the core structure portion via units containing functional groups reactive to hydroxyl groups.

[0013] This novel coating composition is also referred to hereinafter as the composition of the present invention. Preferred embodiments of the invention will become apparent from the following description and dependent claims.

[0014] The present invention also provides a method for producing the aforementioned pigment paste and a method for producing the aforementioned coating composition, particularly a water-based coating composition.

[0015] The present invention also provides coating layers produced from the aforementioned compositions, particularly multi-coat paint systems, wherein one layer is produced by the compositions of the present invention.

[0016] It has been found that by using the coating compositions of the present invention, excellent performance characteristics can be achieved for both coating layers and corresponding multi-coat paint systems. Of particular note are the optimal color characteristics, due to the excellent particle size of the pigments and their dispersion behavior (including dispersion stability) in coating compositions, especially water-based coating compositions.

[0017] describe

[0018] In the case of parameters used for definition or similar performance, the corresponding measurement methods shall be specified in the description and / or explicitly mentioned in the experimental section.

[0019] Unless otherwise explicitly defined, the term "a" (or an equivalent expression describing the singular) should be understood as "at least one". This explicit definition could be, for example, "only one" or "monofacial", thus implying that the term covers only "a" and not "more than one".

[0020] The coating composition of the present invention comprises a pigment paste. As is known to those skilled in the art, a pigment paste is an intermediate product applied to a coating composition, which enables the appropriate integration of pigments and corresponding particles into the composition. Pigment pastes in the coating industry significantly facilitate the technically complex process of pigment dispersion and thus the integration and stabilization of pigments in the composition. The pigments in the pigment paste are optimally wetted and very well dispersed, resulting in an improved distribution in the coating composition. This generally improves the properties of the coating and the resulting paint system, such as a particularly uniform color or color distribution in the paint system. However, in the production of these pastes, precisely matched paste base components must be used to obtain an optimally regulated paste. Without individually matched and precisely selected paste bases, specific pigments often cannot be optimally dispersed, resulting in suboptimal performance characteristics of the final paint system. In other words, the paste base plays a crucial role in the paste production process, i.e., when pigments and paste bases, along with solvents and / or water, and, if necessary, other conventional additives, are mixed and ground / dissolved to reduce the particle size of the pigments, finely distribute them, and stably disperse them. As mentioned in the introduction above, particle size reduction and stability / dispersion are particularly challenging for organic pigments. Surprisingly, aryl-modified branched reaction products (P) are perfectly suited as the base material for this paste, which means achieving the aforementioned technical advantages.

[0021] As can be seen from the foregoing, in the context of this invention, the phrase "coating composition comprising pigment paste" means that the pigment paste is contained in the coating composition as is, i.e., as pre-prepared, meaning that the intermediate product is mixed with the other components of the composition after its own production. Therefore, before adding the pigment paste as is as is, as part of the preparation of the coating composition according to this invention, the compounds and solvents contained in the pigment paste at its completion are mixed / dispersed in the same pigment paste. Clearly, the pigment paste is thus the composition itself, which can be stored and transported separately before being applied at some point in time to produce the coating composition.

[0022] The first component of the pigment paste is a specific reaction product (P).

[0023] The reaction product (P) comprises a core structural moiety and a shell structural moiety. The terms core structural moiety and shell structural moiety are used to better illustrate and distinguish the two fundamental parts of the reaction product (P): a first part (i.e., the core structural moiety) predominantly located at the center of the resulting molecule, and a second part covalently linked to the core structural moiety and therefore predominantly located in the outer region of the resulting molecule. In this application, the term “predominantly” means that, at least for reasons related to the technical synthesis, it is impossible for a theoretically idealized quantitative transformation to always occur in perfect accordance with theoretical expectations. Instead, as those skilled in the art know, side reactions, for example, can be expected. The phrase “structural moiety” should also be understood to describe chemical groups and units that do not necessarily need to be directly covalently linked to each other individually, as they belong to the same structural moiety. For example, the shell structural moiety contains individual units that are not directly covalently linked because they react with different hydroxyl groups of the core structural moiety.

[0024] The reaction product (P) contains a multi-hydroxyl functional core structure in the reaction form, that is, the hydroxyl groups of the molecule that make up the core are the structural parts of the reaction described below.

[0025] The molecule (or compound) constituting the core is named compound (c) and is polyhydroxy functional, meaning it contains an average of at least three hydroxyl groups. This also aligns with the fact that the reaction product (P) is branched, meaning it has at least one branched side, which makes at least three of the three branches outwardly oriented. The term "average" is used to mean that both (cI) monomeric polyhydroxy functional compounds and / or (cII) reaction product / oligomer / polymer (also known as prepolymer) compounds can be used as the molecules constituting the core. As those skilled in the art will appreciate, class (cII) includes compounds such as oligomers or polymers that can be described solely by average parameters such as average molecular weight or average hydroxyl functionality.

[0026] Compound (c) may be selected from monomeric polyols (cI) such as triols, dimers of triols, tetraols, dimer tetraols, 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, trimethylolamine, triethylolamine, trihydroxypropylamine, erythritol, pentaerythritol, diglycerol, triglycerides or higher condensates of glycerol, di(trimethylolpropane), dipentaerythritol, pentaerythritol ethoxylate, pentaerythritol propoxylate, trimethylolpropane... Isocyanurates, trihydroxyethyl isocyanurate (THEIC), trihydroxypropyl isocyanurate, inositol or sugars such as glucose, fructose or sucrose, sugar alcohols such as xylitol, sorbitol, mannitol, threitol, erythritol, arbutinol (ribitol), arabinitol (lyxitol), xylose, galactitol, maltitol, isomaltitol, and polyether alcohols with a functionality of 3 or greater based on the reaction of alcohols with a functionality of 3 with ethylene oxide, propylene oxide and / or butene oxide.

[0027] In some preferred embodiments, the polyol (CI) is at least one selected from erythritol, pentaerythritol, dipentaerythritol, tripentaerythritol, trimethylolethane, trimethylolpropane, trimethylolbutane, glycerol, di(trimethylolethane), di(trimethylolpropane), pentaerythritol ethoxylate, and pentaerythritol propoxylate.

[0028] As described above, the polyol (c) may also be selected from compound (cII), which is a reaction product / oligomer / polymer (prepolymer) compound. Preferably, it is a compound prepared by reacting a monomeric polyol with at least a difunctional compound capable of linking two or more polyols together. Suitable and preferred monomeric polyols are the polyols (cI) described above. Suitable and preferred compounds that react with polyols are aliphatic dicarboxylic acids having 6-36 carbon atoms or esterifiable derivatives of such aliphatic dicarboxylic acids. Another preferred class of compounds (cII) can be prepared by reacting a monomeric polyol with a monocarboxylic acid having at least two hydroxyl groups, such as dimethylolpropionic acid.

[0029] The aforementioned aliphatic dicarboxylic acids having 6-36 carbon atoms, or esterifiable derivatives thereof, can be linear, branched, or cyclic, wherein cyclic dicarboxylic acids preferably comprise at least 6 carbon atoms (including the carbon atom of the carboxylic acid group) in a non-cyclic segment. Non-limiting examples of suitable dicarboxylic acids include adipic acid, octanoic acid, azelaic acid, sebacic acid, undecanoic acid (brassic acid), dodecanoic acid, guaiac acid, hexadecanoic acid (taproic acid), octadecanoic acid, tetradecanoic 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. Dimer fatty acids having 36 carbon atoms are known to have various isomers. Dimer fatty acids are commercially available, for example, from BASF under the trade name... Acquired by Arizona Chemical under the trade name UNIDYME TM Acquired by Croda International Plc under the trade name Pripol TM Obtained and manufactured by Emery Oleochemicals Dimer acids are obtained. Esterifiable derivatives of dicarboxylic acids having 6-36 carbon atoms include mono- or diesters of dicarboxylic acids with aliphatic alcohols having 1-4 carbon atoms, preferably methyl and ethyl esters, and acid anhydrides. Adipic acid is a highly preferred carboxylic acid.

[0030] To prepare this preferred compound (cII), the ratio of the molar number of the monomeric polyol to the molar number of the dicarboxylic acid or aliphatic dicarboxylic acid esterifiable derivative is preferably 2.0-2.5, more preferably 2.0-2.2, and even more preferably 2.0-2.07 molar polyol / molar dicarboxylic acid or aliphatic dicarboxylic acid esterifiable derivative.

[0031] The preferred reaction of a monomeric polyol with a preferred aliphatic dicarboxylic acid or esterifiable derivative, i.e., the esterification reaction, can be carried out by known standard methods. Reaction conditions such as temperature, catalyst, solvent, and reaction process can be individually adjusted. For completeness, reference is made to

[0024] to

[0029] of US 2016 / 0017175 A1 and

[0089] to

[0094] of US 2019 / 0106592 A1, and the steps (a0) described therein, which are clearly and completely incorporated herein by reference.

[0032] The preparation of (cII) class compounds obviously means increasing the (average) number of hydroxyl functional groups per molecule, thereby increasing the number of branched sides of the core structure and thus increasing the branching properties of the reaction product (P).

[0033] Clearly, the hydroxyl (average) values ​​of the compounds constituting the main core structural part are 3-20, more preferably 6-16.

[0034] In the case of compounds in which an average hydroxyl value is used, this value is determined by analyzing the number-average molecular weight and hydroxyl content.

[0035] In some embodiments, the core compound (c) is a reaction product of compound (cII), particularly a polyol (cI) and an aliphatic dicarboxylic acid having 6-36 carbon atoms or an esterifiable derivative of such aliphatic dicarboxylic acid. It may be advantageous to carry out the reaction with the aromatic carboxylic acid concurrently with the preparation of compound (cII), i.e., the preparation of the core compound (cII) and the step of attaching the aromatic unit of the shell structure portion of the reaction product (P) are carried out simultaneously.

[0036] The reaction product comprises a shell structure in a reactive form, which contains an aromatic unit as a first basic part. The aromatic unit is covalently linked to the core structure via a unit containing a functional group reactive to a hydroxyl group. In other words, the aromatic unit is covalently linked to the core structure by reacting its corresponding functional group with the hydroxyl group of the core. Therefore, an aromatic unit can be introduced by a compound containing an aromatic unit and a unit containing at least one functional group reactive to a hydroxyl group. Such compounds are also referred to as compound (d). The aromatic unit can also be introduced via a two-step procedure: a first reaction of the core structure and its hydroxyl group with a first compound (d1) having a first functional group reactive to a hydroxyl group and a second functional group reactive to a second compound (d2), wherein the second compound (d2) contains an aromatic group and a functional group reactive to the second functional group of compound (d1).

[0037] Compound (d) can be selected and varied from a wide range of compounds, as long as the above criteria are met. Potentially reactive functional groups to the hydroxyl group are, for example, carboxyl, isocyanate, or anhydride groups. Those skilled in the art know which compounds are commonly used and can also select, for example, appropriate reaction conditions to achieve the attachment of the corresponding aromatic unit.

[0038] In a preferred embodiment, the aromatic unit is attached via the reaction of the hydroxyl group of the core compound with an aromatic or arylita (aromatic and aliphatic) carboxylic acid, i.e., via esterification of the carboxylic acid group and the hydroxyl group. This esterification can also be carried out by known standard methods. For completeness, reference is made to

[0089] through

[0094] of US 2019 / 0106592A1 and to the steps (a) described therein. These paragraphs are incorporated herein by reference clearly and entirely.

[0039] Therefore, the preferred compound (d) is selected from aromatic or arylita (aromatic and aliphatic) carboxylic acids. Particularly preferred carboxylic acids of formula (I):

[0040]

[0041] Where Ar is an aryl group that is optionally substituted, which is a monocyclic or fused polycyclic aromatic hydrocarbon group; m is 0 or 1; and n is an integer from 0 to 8.

[0042] In some embodiments, Ar is an optionally substituted monocyclic aromatic hydrocarbon group, preferably having 1-3 substituents selected from straight-chain or branched alkyl groups having 1-6 carbon atoms, alkoxy groups having 1-6 carbon atoms, alkoxyalkyl groups having 1-6 carbon atoms in the alkyl moiety, halogens, phenyl groups, and hydroxyl groups. In some embodiments, Ar represents an optionally substituted fused polycyclic aromatic hydrocarbon group, preferably naphthyl, anthraceneyl, or phenanthreneyl, optionally having 1-3 substituents selected from straight-chain or branched alkyl groups having 1-6 carbon atoms, alkoxy groups having 1-6 carbon atoms, alkoxyalkyl groups having 1-6 carbon atoms in the alkyl moiety, halogens, phenyl groups, and hydroxyl groups.

[0043] In some embodiments, the carboxylic acid (d) is represented by formula (II) or (III):

[0044]

[0045] In formulas (II) and (III), n is an integer of 0 or 1-8, preferably an integer of 0 or 1-4, particularly 0 or 1; o is an integer of 0 or 1-3; and if present, each R is independently selected from straight-chain or branched alkyl groups having 1-6 carbon atoms, alkoxy groups having 1-6 carbon atoms, and alkoxyalkyl groups wherein the alkyl structural moiety has 1-6 carbon atoms, halogens, phenyl groups, and hydroxyl groups. Examples of compounds according to formulas (II) and (III) are described below.

[0046]

[0047]

[0048] In some embodiments, the aromatic carboxylic acid in step (a) is an aryloxy-aromatic carboxylic acid represented by formula (IV) or (IV):

[0049]

[0050] In formulas (IV) and (V), n is an integer of 0 or 1-8, preferably an integer of 0 or 1-4, particularly 0 or 1; o is an integer of 0 or 1-3; and, if present, each R is independently selected from straight-chain or branched alkyl groups having 1-6 carbon atoms, alkoxy groups having 1-6 carbon atoms, alkoxyalkyl groups wherein the alkyl structural moiety has 1-6 carbon atoms, halogens, phenyl groups, and hydroxyl groups. Examples of compounds according to formulas (IV) and (V) are described below.

[0051]

[0052]

[0053] In various embodiments, the equivalence ratio of the hydroxyl group of the core compound to the carboxylic acid group of the aromatic or arylitaic carboxylic acid is 1.5-3.5 equivalence hydroxyl / carboxylic acid group. In the case of the reaction in which a core compound, such as a polyol (CI) and an aliphatic dicarboxylic acid having 6-36 carbon atoms or an esterifiable derivative thereof, is simultaneously formed as described above, it is evident that the amount of hydroxyl group in the core compound is calculated by subtracting the amount of carboxylic acid group in the dicarboxylic acid from the amount of hydroxyl group in the polyol (CI).

[0054] The reaction products are also contained in the shell structure as a second basic part of the polyoxyethylene unit. These units are covalently linked to the core structure by units containing functional groups reactive to hydroxyl groups. In other words, the polyoxyethylene unit is covalently linked to the core structure by the reaction of the corresponding functional group with the hydroxyl group of the core. Therefore, the polyoxyethylene unit can be introduced by a compound containing the polyoxyethylene unit and a unit containing a functional group reactive to hydroxyl groups. Such compounds are also called compounds (e). The polyoxyethylene unit can also be introduced by a two-step procedure, namely, a first reaction of the core structure and its hydroxyl portion with a first compound (e1) having a first functional group reactive to hydroxyl groups and a second functional group reactive to a second compound (e2), wherein the second compound (e2) contains polyoxyethylene groups and functional groups reactive to the second functional group of compound (e1).

[0055] Compound (e) can be selected and varied within a wide range of compounds, provided that the above criteria are met. Potentially reactive functional groups to the hydroxyl group are, for example, carboxyl, isocyanate, or (cyclic) carboxylic anhydride groups. Those skilled in the art know which compounds are commonly used and, for example, the appropriate reaction conditions can be selected to achieve the attachment of the corresponding polyoxyethylene unit. Preferably, with respect to the reactive functional group to the hydroxyl group, compound (e) is monofunctional. The reason is that in this way, without the need for complex reaction processes, it is possible to ensure that compound (e) is attached to only one core structural part rather than two core structural parts, which are then interconnected / bridged by compound (e).

[0056] In a preferred embodiment, the polyoxyethylene unit is attached via the hydroxyl group of the core compound to a compound having a polyoxyethylene unit 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, it is preferred that compound (e) is monofunctional with respect to the functional group reactive to the hydroxyl group. However, in the case of cyclic carboxylic anhydride groups, it is worth mentioning that this group can also be formally considered as a group containing two carboxyl groups, meaning that bridging of the two core structural parts is possible in principle. However, as those skilled in the art will know, cyclic carboxylic anhydrides are significantly more reactive to hydroxyl groups than to free carboxyl groups only due to ring strain, meaning that by controlling reaction conditions such as temperature and / or catalysts, it can be ensured that only or at least primarily the reaction of cyclic anhydrides ultimately leads to a reaction product having a free carboxylic acid group. Therefore, in regard to the above-mentioned preferred monofunctional properties of compound (e), in the case of cyclic carboxylic anhydrides, the anhydride is considered to be a group that is reactive to the hydroxyl group, while the resulting free carboxyl group is not considered to be such a group because it does not exist before the reaction and also because its generally given reactivity can be suppressed by the reaction conditions as described above.

[0057] However, experience shows that the reaction with monoisocyanate compound (e) has an advantage in terms of the polydispersity of the resulting reaction product, which is also the reason why isocyanates are preferred as functional groups.

[0058] The polyoxyethylene unit of the reaction product (e) can be, for example, -((CH2-CHR1). n -O) m - where R1 refers to hydrogen (H) and / or an alkyl residue having 1-3 carbon atoms, preferably hydrogen and / or methyl, wherein residues R1 may be the same or different, n refers to 1-3 and m refers to 10-100, preferably 20-50. Examples of this type of unit are polyoxybutene, polypropylene, polyethylene, or mixed copolymers containing different of the aforementioned polyoxyolefins as block copolymers. Polypropylene and / or polyethylene and their mixed copolymers are preferred, with polyethylene being particularly preferred.

[0059] The foregoing means that compound (e) in the first preferred embodiment is selected from compounds having a polyoxyethylene unit and only one isocyanate group, and without any other functional groups reactive to hydroxyl groups. In the context of these compounds (e), the preferred cases defined above with respect to the polyoxyethylene unit generally also apply.

[0060] Therefore, these compounds (e) can be prepared by reacting a standard polyalkylene glycol alkyl ether (i.e., a polyalkylene glycol having an alkylated hydroxyl group) with a diisocyanate compound to obtain a compound having an isocyanate group.

[0061] As diisocyanate compounds, well-known aliphatic, cycloaliphatic, aliphatic-cycloaliphatic, aromatic, aliphatic-aromatic and / or cycloaliphatic-aromatic diisocyanates are available to those skilled in the art. For example, the following diisocyanates may be mentioned: 1,3- or 1,4-phenylene diisocyanate, 2,4- or 2,6-toluene diisocyanate, 4,4'- or 2,4'-diphenylmethane diisocyanate, 1,4- or 1,5-naphthalene diisocyanate, diisocyanate diphenyl ether, trimethylene diisocyanate, tetramethylene diisocyanate, ethyl ethylene diisocyanate, 2,3-dimethyl ethylene 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. Diisocyanates, tetradecylmethylene 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-diisocyanatocyclohexane, 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, tetramethylphenyldimethyl diisocyanate (TMXDI) such as m-tetramethylphenyldimethyl diisocyanate or mixtures of these diisocyanates.

[0062] The reaction conditions for hydroxyl groups and isocyanates are absolutely standard and well-known. In the cases discussed here, it is important to select conditions that ensure only one isocyanate group reacts with the polyalkylene glycol alkyl ether. At least for this reason, a particularly preferred isocyanate is isophorone diisocyanate (IPDI). The reason is that the two isocyanate groups of this formed and usable diisocyanate are not identical in reactivity, meaning that through skillful control of reaction conditions such as temperature and catalyst selection, a one-sided reaction of the isocyanate can be ensured (whereby side reactions are generally considered practically unavoidable and must be accepted).

[0063] In the second preferred embodiment (however, it is not preferred compared to the first preferred embodiment using the special compound (e) described above), the two compounds (e1) and (e2) described above are used.

[0064] Compounds (e1) and (e2) can be selected and varied from a wide range of compounds, as long as the above criteria are met. Those skilled in the art will know which compounds are typically used and, for example, the appropriate reaction conditions can be selected to achieve the attachment of the corresponding polyoxyethylene unit.

[0065] Preferred compounds (e1) are selected from cyclic carboxylic 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-cyclohexanedicarboxylic anhydride, indigo anhydride, biphenyl dicarboxylic anhydride, etc. Substituted anhydrides, particularly those with lower alkyl substituted forms such as butyl succinic anhydride, hexyl succinic anhydride, octyl succinic anhydride, butyl maleic anhydride, pentyl maleic anhydride, hexyl maleic anhydride, octyl maleic anhydride, butyl glutaric anhydride, hexyl glutaric anhydride, heptyl glutaric anhydride, octyl glutaric anhydride, alkyl cyclohexanedicarboxylic anhydride, and alkyl phthalic anhydrides such as 4-n-butyl phthalic anhydride, hexyl phthalic anhydride, and octyl phthalic anhydride. Succinic anhydride is particularly preferred.

[0066] Since, by definition, compound (e1) contains two functional groups for the reaction (see above), those skilled in the art will readily understand that, with regard to the preferred cyclic carboxylic anhydrides and the fact that these anhydrides can be formally considered as compounds having two carboxyl groups (where the second carboxyl group is generated as part of the cyclic anhydride after the first carboxyl group reacts), it should be understood that, by definition, both functional groups of compound (e1) are carboxylic acid groups for this type of cyclic carboxylic anhydride. Therefore, with regard to the aforementioned preferred bifunctionality of compound (e1), in the case of cyclic carboxylic anhydrides, the anhydride is considered to have two functional groups, namely two carboxylic acid groups.

[0067] Therefore, in this preferred embodiment, the second compound (e2) comprises a polyalkylene group and a functional group reactive to a carboxyl group. A hydroxyl group is preferred, meaning the reaction is carried out via esterification. Therefore, the preferred compound (e2) is the aforementioned polyalkylene glycol alkyl ether. In the context of these compounds (e2), the preferred cases defined above with respect to the polyoxyethylene unit generally also apply.

[0068] Even though suitable reaction products (P) can be formed through the second clearly described embodiment, these products are not as advantageous as those prepared by compound (e), especially those with an isocyanate group, because of their relatively high polydispersity.

[0069] The equivalence ratio of the hydroxyl group of the nuclear compound to the functional group that is reactive to the hydroxyl group of the compound (e) or (e1) is 2-14 equivalence hydroxyl groups / functional groups reactive to the hydroxyl group.

[0070] As described above, the equivalence ratio of the hydroxyl group of the nuclear compound to the carboxylic acid group of the aromatic or araliphatic carboxylic acid (d) is 1.5-3.5 equivalence hydroxyl / carboxylic acid group.

[0071] In the two equivalence ratios mentioned above, it refers to the amount of hydroxyl groups of the initially unreacted nuclear compound. Therefore, it is clear that the amounts of the carboxylic acid group of compound (c) and the reactive group of compound (e) or (e1) preferably do not exceed the amount of hydroxyl groups of the nuclear compound (because this would mean the presence of unreacted compounds (d) and / or (e) and / or (e1) in the reaction mixture).

[0072] Although it is generally permissible to react nuclear compound (c) with compound (e) or (e1) and (e2) before or simultaneously with the reaction with compound (d), it is preferable (i) to react compound (c) and (d) first, and then (ii) to react the intermediate produced in step (i) with compound (e) or (e1) and (e2).

[0073] The result of the above process is the reaction product (P).

[0074] In a preferred embodiment of the invention, the reaction product further includes carboxylic acid groups in the shell structure portion, which are covalently linked to the core structure portion via units containing functional groups reactive to hydroxyl groups. These groups can be used for anion stabilization in aqueous media.

[0075] Therefore, the carboxylic acid group is introduced through compounds comprising a carboxylic acid group and a group reactive to the hydroxyl group, such as (other) carboxylic acid groups. Such compounds are also referred to as compound (f). Cyclic carboxylic anhydrides can be used as compounds of this class (f), wherein, for the reasons described above, these anhydrides are formally considered as compounds having two carboxylic acid groups. In fact, this class of cyclic carboxylic anhydrides is a particularly preferred compound (f). The reason is, in principle, as already stated above, that due to the non-equivalent reactivity of the two formally carboxylic acid groups, reaction conditions can be selected such that it is easy to allow the anhydride to be attached to the core structural portion via ring-opening addition without any or only a negligible amount of the resulting free carboxylic acid group (meaning that no or only a negligible bridging of the two core molecules occurs, but the free carboxylic acid group still serves for anionic stabilization). Examples and preferred embodiments of this class of cyclic carboxylic anhydrides are mentioned above.

[0076] As described above, in the production of the reaction product, a compound (e1) preferably being a cyclic carboxylic anhydride can be used. In this case, compounds (e1) and (f) are preferably identical, meaning that the attachment of the carboxylic acid group discussed herein is preferably carried out in the step of attaching compound (e1). Therefore, in this case, the amounts of compounds (e1) and (e2) are adjusted such that the amount of (e1) is always higher than that of (e2), meaning that a free carboxyl group still remains.

[0077] In the case of the reaction product generated by compound (e), the attachment of the carboxylic acid group obviously takes place in a separate step, i.e., by the reaction of the hydroxyl group of the nucleus with compound (f). Even though the reaction with compound (f) can usually be carried out at different stages and / or simultaneously with the other reactions described above, it is advantageous to carry out the reaction after the reaction of the nucleus or the corresponding intermediate with compounds (d) and (e).

[0078] The acid value of the reaction product (P) is preferably 10-60 mg KOH / g (relative to the reaction product (P) itself, i.e., without any potential solvent for dispersing or dissolving the reaction product (P); the amount of the reaction product (P) in the dispersion or solution can be determined by the content of non-volatile matter).

[0079] The amount of reaction product (P) is preferably 1-20% by weight, more preferably 2.5-12.5% ​​by weight, in each case based on the total weight of the pigment paste (also relative to the reaction product (P) itself; unless otherwise clearly specified, this principle also applies to any and all other provisions in this application concerning amount or performance).

[0080] The second basic component of the pigment paste is an organic pigment. The pigment can be selected and varied within a wide range of pigments known to those skilled in the art, such as azo pigments (e.g., monoazo, diazo, β-naphthol, benzimidazolone, condensates, metal complexes, isoindolinone, isoindolin) and polycyclic pigments (phthalocyanine, quinacrine, perylene, pyrenone, diketopyrrolopyrrole, indigofera sulfide, anthraquinones (indansone, anthraquinone pyrimidine, flavanone, pinantrone, dibenzopyrene di ... Azine, triaryl carbon Quinophthalone). In terms of color, pigments such as metallized and nonmetallized azo red, quinacridone red and purple, perylene red, copper phthalocyanine blue and green, carbazole purple, monoaryl and diaryl yellow, benzimidazole yellow, toluene orange, naphthol orange, etc. can be mentioned.

[0081] As is generally known and as stated above, pigment pastes are formulations of pigments in a carrier material (also called a paste resin or paste base), i.e., an organic resin material, in which the pigments are dispersed and present at a higher concentration than in later use. Later use is typically in the production of coating compositions. More specifically, in this type of pigment paste, the weight ratio of pigment to polymer is generally greater than in coating compositions using the paste. In addition to the carrier material (different polymers, also called paste bases), water and / or organic solvents are usually present. Various additives such as wetting agents may also be used.

[0082] As described above, the use of pigment pastes in the coatings industry significantly simplifies the technically complex pigment dispersion process. For example, it ensures dust-free handling of pigments during coating formulation. Furthermore, the optimal wetting and good dispersion of pigments in the paste result in an improved distribution in the coating. This typically leads to improved properties of the coating and the resulting paint system, such as a particularly uniform color or color distribution within the paint system. In the context of this invention, it is evident that the reaction product (P) serves as a carrier material (paste base) to provide finely distributed and stably dispersed organic pigments.

[0083] Therefore, the production of pigment pastes requires the reaction product (P) and the organic pigment to be in contact under high shear conditions sufficient for pigment dispersion, i.e., wetting the surface of the pigment particles with a dispersion resin (P). Thus, as is generally known, the shear introduced by this milling process also breaks down pigment agglomerates into smaller particle sizes, ultimately yielding primary pigment particles. The breakage of agglomerates and the wetting of primary pigment particles are important for pigment stability and color formation. Pigment can typically be used in amounts up to, for example, 2-40% by weight, preferably 5-15% by weight, in each case based on the total weight of the pigment paste. The amount of pigment used depends on the properties of the pigment, its color concentration, and / or the intensity of the desired effect, as well as its dispersibility.

[0084] The ratio of dispersant to pigment in the pigment paste (also referred to as the ratio of reaction product (P) to pigment) is preferably at least 0.2, more preferably at least 0.5, and more preferably at least 0.55 (based on weight in each case). The preferred range is 0.2-1.5, more preferably 0.5-0.8, and even more preferably 0.55-0.75.

[0085] The present invention also provides a method for producing a pigment paste comprising a reaction product (P) and an organic pigment.

[0086] According to the above, the method for producing pigment paste includes (1) contacting the reaction product (P) with an organic pigment, preferably in the presence of water, an organic solvent, and, if applicable, an additive such as a wetting agent, to obtain a corresponding mixture, and (2) exposing the mixture according to (1) to shear force. Suitable organic solvents are, for example, propylene glycol n-butyl ether, Dowanol PnB, ethylene glycol n-butyl ether, and / or butyl cellulose.

[0087] Specifically, step (1) of producing pigment paste is preferably carried out by: (1a) preparing a dispersion comprising reaction product (P), water, organic solvent and, if applicable, additives, and (1b) mixing the dispersion of step (1a) with an organic pigment.

[0088] Step (2), which exposes the mixture from step (1) to shear forces for effective dispersion and to reduce the particle size of the pigment, is preferably carried out by grinding. Suitable grinding equipment, such as high-energy mills, and suitable procedures are well-known and may be selected depending on the specific circumstances. The grinding process is preferably carried out using grinding beads (which are well-known) for a duration of, for example, 1-20 hours. These beads typically have a particle size of, for example, about 0.1 to 10 mm (diameter). The grinding process can also be carried out in different grinding steps, which differ, for example, in terms of bead size, the weight ratio of the mixture to the beads, and / or the grinding duration. After grinding, the prepared dispersion is separated from the grinding beads, particularly by filtration, to obtain the pigment slurry according to the invention.

[0089] The weight ratio of the corresponding components of the pigment paste is, 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, based on the total weight of the pigment paste in each case.

[0090] The pigment paste prepared by the method according to the invention is characterized by excellent pigment particle size properties (i.e., relatively small particle size) and fine pigment distribution, resulting in good dispersion behavior and stability. These properties can be verified, for example, by low scattering, as shown in the Examples section below by measuring the brightness of the cured coating layer.

[0091] The amount of pigment paste in the coating composition of the present invention can be selected according to individual needs and requirements and can be selected as low as 0.1% by weight (e.g., in colored transparent coating compositions) or as high as 25% by weight. Therefore, based on the total weight of the coating composition, the preferred range is 0.1-25% by weight. Even more preferably, the range is 2.5-15% by weight, preferably 3.5-10% by weight, in each case based on the total weight of the coating composition.

[0092] The coating compositions according to the invention may further comprise components known and commonly used in coating compositions.

[0093] The coating composition may contain 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. Other resins or polymers may have functional groups that are reactive to crosslinking agents for other resins or polymers that may be included in the coating composition. In some preferred embodiments, the coating composition contains other resins or polymers having hydroxyl, urethane, or combinations of such groups. In various embodiments, the coating composition contains hydroxyl-functional acrylic polymers, hydroxyl-functional polyesters, and / or hydroxyl-functional polyurethanes. Polysiloxane polyols may also be included. These polymers are well known to those skilled in the art and are widely used as base polymers in coating compositions. The following paragraphs will still describe some further details regarding such compounds (with more detailed and therefore deviating nomenclature, where appropriate).

[0094] Polyvinyl polyols, such as acrylic (polyacrylate) polyol polymers, can be used as hydroxyl-functionalized substances. Acrylic polymers or polyacrylate polymers can be copolymers of acrylic and methacrylate monomers, as well as other copolymerizable polyvinyl monomers. The term "(meth)acrylate" is used to conveniently represent one or both of acrylates and methacrylates, and the term "(meth)acrylate" is used to conveniently represent one or both of acrylics and methacrylates.

[0095] Polyester polyols can be prepared by reacting the following substances: (a) a polycarboxylic acid or its esterifiable derivative, together with a monocarboxylic acid if desired; (b) a polyol, together with a monofunctional alcohol if desired; and (c) other modifying components if desired. Non-limiting examples of polycarboxylic acids and their esterifiable derivatives include phthalic acid, isophthalic acid, terephthalic acid, halophthalic acids such as tetrachlorophthalic acid 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-cyclohexanedicarboxylic acid, 4-methylhexahydrophthalic acid, nethylenetetrahydrophthalic acid, tricyclodecanedicarboxylic acid, nethylenehexahydrophthalic acid, camphoric acid, cyclohexanetetracarboxylic acid, and cyclobutanetetracarboxylic acid. Alicyclic polycarboxylic acids may be used in their cis or trans forms or in mixtures of both. Esterifiable derivatives of these polycarboxylic acids include monoesters or polyesters thereof with an aliphatic alcohol having 1-4 carbon atoms or a hydroxyl alcohol having up to 4 carbon atoms, preferably methyl and ethyl esters, and anhydrides of these polycarboxylic acids in which they are present. Non-limiting examples of suitable monocarboxylic acids that can be used with polycarboxylic acids include benzoic acid, tert-butylbenzoic acid, lauric acid, isononanoic acid, and fatty acids from natural oils. Non-limiting examples of suitable polyols include any of those mentioned above, such as ethylene glycol, butanediol, neopentyl glycol, propylene glycol, butanediol, hexanediol, diethylene glycol, cyclohexanediol, cyclohexanediol, trimethylpentanediol, ethylbutylpropylene glycol, di(trimethylolpropane), trimethylolethane, trimethylolpropane, glycerol, pentaerythritol, dipentaerythritol, trihydroxyethyl isocyanate, polyethylene glycol, polypropylene glycol, and polyols derived from natural oils. Non-limiting examples of monohydric alcohols that can be used with polyhydric alcohols include butanol, octanol, lauryl alcohol, and ethoxylated and propoxylated phenols. Non-limiting examples of suitable modifying components include compounds containing groups reactive to the functional groups of polyesters, including polyisocyanates and / or diepoxides, and, if desired, monoisocyanates and / or monoepoxides. Polyester polymerization can be carried out by known standard methods. The reaction is typically carried out at temperatures of 180–280 °C in the presence of a suitable esterification catalyst (if desired). Typical catalysts for esterification polymerization are protic acids, Lewis acids, titanium alkoxides, and dialkyltin oxides, such as lithium octanoate, dibutyltin oxide, dibutyltin dilaurate, and p-toluenesulfonic acid, under reflux with a small amount of a suitable solvent as an entrainer, such as an aromatic hydrocarbon like xylene, or a (cyclic)aliphatic hydrocarbon like cyclohexane.

[0096] Polyurethanes with hydroxyl functional groups can also be used in coating compositions in conjunction with aryl-modified hyperbranched polyols. Examples of suitable polyurethane polyols include polyester-polyurethanes, polyether-polyurethanes, and polycarbonate-polyurethanes, including but not limited to polyurethanes polymerized using polyethers and polyesters (including polycaprolactone polyester or polycarbonate diol) as polymeric diol reactants. These polymeric diol-based polyurethanes are prepared by reacting a polymeric diol (polyester diol, polyether diol, polycaprolactone diol, polytetrahydrofuran diol, or polycarbonate diol), one or more polyisocyanates, and optionally one or more chain extenders. When used in this context, the chain extender is a compound having two or more functional groups reactive to isocyanate groups, preferably two functional groups, such as diols, amino alcohols, and diamines. Preferably, the polymeric diol-based polyurethane is substantially linear (i.e., substantially all reactants are bifunctional).

[0097] Polysiloxane polyols can be prepared by hydrosilanizing polysiloxanes containing hydrogenated silicon with polyoxyalkylene alcohols containing two or three terminal primary hydroxyl groups, such as allyl polyoxyalkylene alcohols like trimethylolpropane monoallyl ether and pentaerythritol monoallyl ether.

[0098] Any of the aforementioned polyol resins and polymers can be derived to have urethane groups according to known methods, for example, by reacting hydroxyl-functionalized substances with alkyl urethane esters (e.g., methyl urethane or butyl urethane) via so-called "transcarbamation" or "transcarbamoylation". In other methods of forming urethane-functionalized resins and polymers for use in coating compositions, the resins and polymers may be polymerized using urethane-functionalized monomers.

[0099] The coating composition of the present invention may further comprise at least one crosslinking agent or curing agent reactive to hydroxyl groups, such as an amino plastic crosslinking agent having active hydroxymethyl, methylalkoxy, or butylalkoxy groups; a polyisocyanate crosslinking agent having blocked or unblocked isocyanate groups; a polyanhydride; and a polyepoxy functional crosslinking agent or curing agent that is reactive to hydroxyl groups and any carboxylic acid groups of aryl-modified hyperbranched polyols. An amino plastic crosslinking agent is preferred.

[0100] The coating composition may further contain solvents, other pigments, fillers, or conventional additives. However, coating compositions that do not contain any other pigments are preferred, except for those contained in the pigment pastes described above.

[0101] The total solids ratio of the pigment (or pigment solids) / coating composition can vary depending on individual needs and also on the nature of the pigment, color concentration and / or the intensity of the desired effect, as well as the dispersibility of the pigment. However, the preferred range of this ratio is 0.05-0.35, more preferably 0.05-0.2, and even more preferably 0.075-0.15 (by weight in each case).

[0102] Potential applications of the coating compositions of the present invention are as transparent, colored topcoats (or colored clear coats), meaning and thus intended for use as upper layers in multilayer components. However, in a preferred embodiment, the coating compositions of the present invention are basecoat compositions, preferably water-based, meaning and thus intended for use as intermediate coloring coatings (e.g., for automotive finishing and general industrial coatings). This basecoat is typically applied to a substrate that has been pretreated with a first two coat of mixed primer and / or another basecoat below the basecoat of the present invention. The substrate may also include existing paint systems, which may optionally require pretreatment (e.g., by abrasion). In particular, to protect the basecoat film from environmental effects, at least one additional clear coat film is typically applied over it. This is typically done in a wet-on-wet process, i.e., the clear coat material is applied before the basecoat film has cured. Curing then occurs, finally together with the clear coat.

[0103] The present invention also relates to a method for producing a coating layer on a substrate by applying the coating composition of the present invention to a substrate, forming a film from the applied coating composition, and curing the applied coating composition to obtain a cured coating layer.

[0104] The coating composition can be applied using any of the many techniques known in the art. These include, for example, spraying, dipping, rolling, curtain coating, squeegeeing, spreading, pouring, impregnation, immersion, dripping, or rolling. For automotive body panels, spraying is typically used. Spray application methods are preferred, such as compressed air spraying, airless spraying, high-speed rotation, and electrostatic spraying (alone or in combination with thermal spraying such as hot air spraying).

[0105] The coating compositions described herein are specifically designed for use in automotive OEM finishing and automotive repair applications where technical and aesthetic requirements are particularly stringent. The coating compositions can be used in both single-step and multi-step coating methods. Therefore, the present invention also provides a multi-layer coating system comprising at least one colored base coat film based on the coating composition of the present invention and may have at least one transparent coating disposed thereon.

[0106] The applied coating composition typically cures after a settling time or "flash" time. Settling time is used, for example, for leveling and devolatiles of the coating film, or for the evaporation of volatile components such as solvents. Settling time can be assisted or shortened by applying increased temperature or decreasing humidity, provided that this does not cause any damage or alteration to the coating film, such as premature full cross-linking. Thermocuring of the coating composition is not particularly specific in method, but is instead carried out according to typical known methods, such as heating in a forced-air oven or irradiation with an IR lamp. Thermocuring can also be carried out in stages. Another preferred curing method is curing with near-infrared (NIR) radiation. Although various curing methods can be used, thermocuring is preferred. Thermocuring is typically carried out by exposing the coated article to an elevated temperature provided primarily by a radiant heat source. After application, the applied coating layer is cured, for example, by heating at a temperature of 30-200°C, 40-190°C, or 50-180°C for 1 minute to 10 hours, more preferably 2 minutes to 5 hours, particularly 3 minutes to 3 hours; however, longer curing times may be used at temperatures used for automotive repair (preferably 30-90°C). The coating compositions of the present invention can be used for repair coatings and for initial finishing coatings cured at higher temperatures. Typical methods of applying the repair coating composition include application and drying, wherein curing is carried out at room temperature or at elevated temperatures of 30-90°C. OEM coatings are typically cured at higher temperatures, for example, at about 110 to about 135°C. Curing time varies depending on the specific components used and physical parameters such as layer thickness; however, for closed acid-catalyzed systems, typical curing time is about 15 to about 60 minutes, preferably about 15-25 minutes, and for unclosed acid-catalyzed systems, it is about 10 to 20 minutes. In a multi-coat coating system comprising at least one colored base coat film based on the coating composition of the present invention and at least one transparent coating disposed thereon, curing is preferably carried out together, i.e., the base coat and the transparent coating are applied wet to wet, and then cured in a final curing step.

[0107] The resulting cured base coat can have a thickness of approximately 5 to approximately 75 micrometers, depending primarily on the desired color and the thickness required to form a continuous layer that provides the color. Typically, the resulting cured base coat has a thickness of approximately 30 to approximately 65 micrometers.

[0108] The coating composition 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 can also be any of these materials with other coatings, either cured or uncured, already present, such as electrodeposited primer layers, first and second coat mixed primer layers, and / or base coats.

[0109] A primer may first be applied to the substrate using an electrodeposition (electrophoretic) primer. The electrodeposition composition can be any electrodeposition composition used in motor vehicle coating operations. Non-limiting examples of electrophoretic paint compositions include those sold by BASF. Electrodeposition coating baths typically comprise an aqueous dispersion or emulsion containing a primary film-forming epoxy resin with ion-stabilizing (e.g., amine salting) action in water or a mixture of water and an organic co-solvent. A crosslinking agent is emulsified with the primary film-forming resin, which may react with functional groups on the primary resin under suitable conditions (e.g., heat application), thereby curing the coating. Suitable examples of crosslinking agents include, but are not limited to, blocked polyisocyanates. Electrodeposition coating compositions typically contain one or more pigments, catalysts, plasticizers, coalescing agents, defoaming agents, flow conditioners, wetting agents, surfactants, UV absorbers, HALS compounds, antioxidants, and other additives.

[0110] The electrodeposited coating composition is preferably applied with a dry film thickness of 10-35 μm. After application, the coated vehicle body is removed from the bath and rinsed with deionized water. The coating can be cured under suitable conditions, for example by baking at about 135°C to about 190°C for about 15 to about 60 minutes.

[0111] Finally, the present invention relates to a cured coating layer, preferably a cured multilayer coating system prepared according to a pre-described method, wherein the coating composition of the present invention is applied as a base coat composition. In this cured coating layer, preferably in a cured multilayer coating system, the base coat composition is able to achieve optimal color properties, such as, in particular, high transparency (low scattering) and high color concentration. Example

[0112] Measurement method:

[0113] 1. Determination of non-volatile fractions

[0114] The amount of solids content (non-volatile matter, non-volatile content, solid fraction or similar substances), including total solids content, is determined by DIN EN ISO 3251:2019-09 at 110°C for 60 minutes.

[0115] 2. Measurement of color values ​​(L*, a*, b*)

[0116] The L*a*b* color space or L*a*b* color model (i.e., the CIELAB color model) is known to those skilled in the art. The L*a*b* color model is standardized, for example, in DIN EN ISO / CIE 11664-4:2020-03. In the L*a*b* color space, each perceptible color is described by coordinates {L*, a*, b*} in a three-dimensional coordinate system at a specific color position. The a* axis describes the green or red portion of the color, where negative values ​​represent green and positive values ​​represent red. The b* axis describes the blue or yellow portion of the color, where negative values ​​represent blue and positive values ​​represent yellow. Therefore, lower values ​​indicate a more blue color. The L* axis is perpendicular to the plane and represents lightness (luminance). The endpoints of the L* axis are black (L=0) and white (L=100). Therefore, lower values ​​indicate a darker color. The color values ​​L*, a*, and b* of the coated substrate (after curing) are determined according to ASTM E 284-81a after its preparation (including curing). These values ​​were measured using the BYK-mac i (BYK-Gardner) instrument. Analysis of the cured samples was performed using the standard operating procedures of the BYK-mac i spectrophotometer, based on measurements of color, sparkle, and fragility. The fully cured samples to be analyzed were wiped with a microfiber cloth. The BYK-mac i instrument was then placed on the substrate surface and measurements were taken at angles of -15°, 15°, 25°, 45°, 75°, and 110° using a D65 light source, with data recorded for each angle using CIELab settings. The measurements were performed at different locations on separate panels, and the values ​​are averages of the individual tests and reported. The color values ​​L*, a*, and b* reported below in the Experimental section pertain to the 110° angle.

[0117] In this application, this method is used because higher-particle-size pigment agglomerates result in more scattered light, which increases the measured brightness value of the cured coating film. Since the 110° angle has the longest film path length, it is most sensitive to detecting the increase in scattering. Therefore, the L value (brightness) at the 110° angle is used for evaluation, and a lower value indicates a more transparent and better dispersion.

[0118] Typically, a value greater than 3.5 in L110° reflects brightness corresponding to unacceptable pigment distribution and therefore unacceptable transparency. Values ​​less than 3.0 can be rated as good, while values ​​less than 2.5 indicate excellent pigment distribution / dispersion and therefore excellent transparency.

[0119] 1. Synthesis of reaction products (P)

[0120] The following paragraphs 1.1 to 1.2 describe detailed synthetic schemes for two types of reaction products (P) to be used according to the present invention. The synthetic schemes for these types of reaction products (P) are exemplarily used for the reaction products (P) shown in Table 1. This means that although the overall and basic reaction conditions are applied accordingly, specific details regarding the precipitates and molar amounts may be adjusted if necessary or appropriate. Furthermore, details regarding the actual selection of precipitates and molar amounts are shown in Table 1.

[0121] 1.1 Type 1 reaction product (P)

[0122] Tripentaerythritol (compound (cI)), 2-naphthoxyacetic acid (compound (d)), DBTO (catalyst, 0.1 wt%), and xylene (3.5 wt%) were charged into a reactor and heated to 230 °C, then reacted at above 200 °C for 2 hours, during which the generated water was continuously removed. After the reaction time, the residual water and xylene were removed, the mixture was cooled to 140 °C, and ethyl 3-ethoxypropionate (EEP) (26.4 wt%) and n-butyl acetate (10.8 wt%) were added.

[0123] In a separate reaction step, polyethylene glycol methyl ether and isophorone diisocyanate (IPDI) are reacted in equal molar amounts to form compound (e). Polyethylene glycol methyl ether (MPEG 2000) is then charged into a reactor and heated to 110°C (-200 mm HG vacuum) to melt and remove entrained water (60–90 min). The reactor is then cooled to 60°C and the vacuum is stopped. Next, in the first step, isophorone diisocyanate is charged directly as quickly as possible, followed by dibutyl dilaurate (0.1 wt%), while the temperature is maintained below 70°C. After a reaction time of 2–3 hours at 65°C, the reaction mixture is cooled and the monoisocyanate functional compound (e) is isolated.

[0124] In the third reaction step, compound (e) and the reaction products of compounds (c) and (d) are heated to 75°C and treated for 1–3 hours with 0.06 wt% dibutyltin dilaurate until all NCO has reacted. Subsequently, the reactor is heated to 120°C and a loading of succinic anhydride (compound (f)) and EEP (1.3 wt%) is added. After a treatment time of 2–5 hours at 145°C, the mixture is cooled to 60°C. Then, a loading of 0.768 wt% EEP and 0.3 wt% n-butyl acetate is added. Finally, the nonvolatile content is adjusted with 2-butoxyethanol, where in most cases, a content of approximately 60% is suitable.

[0125] 1.2 Type 2 reaction product (P)

[0126] Tripentaerythritol (compound (cI)), 2-naphthoxyacetic acid (compound (d)), DBTO (catalyst, 0.1 wt%), and xylene (3.5 wt%) were then added to a reactor and heated to 230 °C. The mixture was then reacted at above 200 °C for 2 hours, during which the generated water was continuously removed. After this reaction time, the residual water and xylene were removed, the mixture was cooled to 140 °C, and ethyl 3-ethoxypropionate (EEP) (26.4 wt%) and n-butyl acetate (10.8 wt%) were added.

[0127] In the second reaction step, the reaction products of compounds (cI) and (d) were loaded into a reactor and succinic anhydride (compound (e1)) and EEP (1.1 wt%) were added. The reaction mixture was treated at 145 °C for 2–5 hours to obtain an intermediate.

[0128] Finally, the aforementioned intermediate and poly(ethylene glycol) methyl ether (MPEG 2000, compound (e2)) were heated to 230°C in a reactor with 0.11 wt% DBTO and 3.5 wt% xylene. The mixture was then treated at above 200°C for 6–7 hours, during which the resulting water was continuously removed. After this reaction time, the residual water and xylene were removed, the mixture was cooled to 140°C, and EEP (1.0 wt%) and n-butyl acetate (0.4 wt%) were added. Finally, if appropriate, the nonvolatile content was adjusted by adding 2-butoxyethanol.

[0129] 1.3 Notes:

[0130] Table 1 below also shows that the product (P) obtained by using the product (obtained by first reacting dipentaerythritol and adipic acid in a standard esterification reaction at a molar ratio of 2:1 to obtain compound (cII)) was used instead of the products obtained by using the above-mentioned compounds (cI) and (d). This compound (cII) (containing an average of 10 hydroxyl groups per molecule) was then used accordingly in other reaction processes.

[0131] 1.4 The reaction products (P) produced

[0132] Table 1 lists the reaction products.

[0133] Therefore, for reaction products of type I, the nominal molar ratio w / x / y / z describes the nominal ratio of "hydroxyl group (w) of the core structural moiety (compound (cI) or (cII)) / carboxyl functional group (x) of compound (d) / NCO functional group (y) of compound (e) / reactive carboxyl side group (z) of anhydride compound (f)".

[0134] For reaction products of type 2, the nominal ratio q / r / s / t describes "hydroxyl group (q) of the core structural moiety (compound (cI) or (cII)) / carboxyl functional group (r) of compound (d) / carboxyl side group (s) of anhydride compound (e1) that is reactive to the hydroxyl group of the core / hydroxyl group (t) of compound (e2) that is reactive to the resulting carboxyl side group of the open-ring anhydride compound (e1)".

[0135] As a comparative reaction product (CP), a known pigment dispersant additive (also containing polyoxyethylene units (in the form of reactant MPEG2000)) was used. The dispersant used comprised 35.5 wt% resin solids (non-volatile) and 64.5 wt% solvent. The solvent content of the dispersant was as follows: 28.4 wt% propylene glycol n-propyl ether, 6.1 wt% methyl isopentyl ketone (MIAK), 28.5 wt% deionized water, and 1.5 wt% mineral oil. The resin present in the dispersant was prepared as disclosed in Example 5 of U.S. Patent No. 5,270,399.

[0136] Table 1: Reaction Products (P)

[0137]

[0138]

[0139] 2. Preparation of pigment paste and coating composition

[0140] 2.1 Pigment paste

[0141] Pigment pastes are produced according to the following general procedure: A given pigment is weighed into a container. Then, a given reaction product (P) as a dispersant is added to a separate container to achieve a predetermined dispersant-to-pigment level. The reaction product is then slowly diluted in water with stirring. After complete dissolution, propylene glycol n-butyl ether (Dowanol PnB) is added dropwise with stirring to remove turbidity from the solution. The dispersion of the reaction product is then mixed with the pigment with stirring to form a consistent pre-paste formulation / suspension. Subsequently, if necessary, a coarse grinding step is performed. In any case, fine grinding is performed.

[0142] Blue Pigment Paste: For the blue pigment paste, use Palomar Blue 248-4806, Blue 15:1 (SunChemical). Add 10 parts by weight of pigment to a stirred mixture containing the specified reaction product as a dispersant, which also contains propylene glycol n-butyl ether (Dowanol PnB) and water. Agitate the resulting suspension for 5 minutes using a Cowles blade. Adjust the pH to 8.0 using a 20% DMEOA aqueous solution, measured with a Starter 300pH portable pH meter (Ohaus Corporation, Parsippany, New Jersey, USA). Transfer the pigment suspension to an 8-ounce mixing tank (Qorpak) and 0.3–0.4 mm YTZ grinding media (Fox Industries) at a ratio of 2:1, and agitate for 10 hours using an LAU vibrator (LAU disperser DAS200-LAU GmbH). Separate the resulting slurry from the 0.3–0.4 mm YTZ media by weight filtration and use it in coating compositions without further modification.

[0143] Black Pigment Paste: For black pigment paste, use Paliogen Black L0086. Add 10 parts by weight of the pigment to a stirred mixture containing a specified reaction product as a dispersant, which also contains propylene glycol n-butyl ether (Dowanol PnB) or Dowanol PnP and water. Stir the resulting suspension for 5 minutes using a Cowles blade. Adjust the pH to 8.1 using a 20% DMEOA aqueous solution, measured with a Starter 300pH portable pH meter (Ohaus Corporation, Parsippany, New Jersey, USA). Transfer the pigment suspension to an 8-ounce mixing tank (Qorpak) and 0.9–1.1 mm YTZ grinding media (Fox Industries) at a ratio of 2:1, and coarsely grind using an LAU vibrator (LAU disperser DAS 200-LAU GmbH) for 4 hours. Separate the 0.9–1.1 mm YTZ media by gravimetric filtration. The collected slurry was transferred to an 8-ounce mixing tank (Qorpak) and infused with 0.3–0.4 mm YTZ grinding media at a 2:1 bead-to-slurry ratio. The mixture was then agitated for 12 hours using a LAU vibrator (LAU disperser DAS 200-LAU GmbH) for fine grinding. The resulting final slurry product was filtered to remove the 0.3–0.4 mm media and used in coating compositions without further modification.

[0144] Tables 2 and 3 also provide further details regarding pigment pastes. All quantities refer to weight. In cases where the component is available as a dispersion / solution and therefore contains a solvent, the quantity refers to the component applied (i.e., with solvent), while the dispersant to pigment ratio refers only to the effective amount of dispersant (excluding the solvent) and pigment.

[0145] 2.2. Coating Composition

[0146] The composition is achieved by adding the aforementioned pigment paste to a non-colored, one-component composition intermediate, adjusting the solids content using a polyurethane resin component, adjusting the pH to 8.1 using NN-dimethylethanolamine (20% in water), and adjusting to the target pigment concentration by adding water. The non-colored intermediate is water-based and, in particular, contains Laponite (Fa.BYK) as a rheology modifier, as well as polyurethane, acrylic resins, and polyesters as base components. Furthermore, melamine resin (Cymel 327, Fa Allnex) is included as a crosslinking agent component.

[0147] This results in the coating compositions of the present invention, in this case, a transparent blue undercoat composition or a black undercoat composition.

[0148] Tables 2 and 3 also provide further details regarding the coating compositions. All quantities refer to weight. In the case of components that are available in dispersion / solution form and therefore contain solvent, the quantity refers to the component applied (i.e., with solvent), while the dispersant to pigment ratio refers only to the effective amount of dispersant (excluding solvent) and pigment.

[0149] 3. Preparation and evaluation of cured coatings

[0150] 3.1 Application of the transparent base coat composition containing blue pigment

[0151] The composition was applied as a film onto a Melinex stencil (Puetz GmbH + Co. Folien KG, Taunusstein, Germany) using a Byk stencil with a 100-micron slit. The wet transparent base coat was flash-evaporated under ambient conditions for 15 minutes and then calcined at 130°C for 25 minutes.

[0152] Subsequently, the cured coating on the polyester film (melinex) substrate was analyzed using a Byk Maci spectrophotometer. The sample was placed on a mirror with the coating facing the mirror surface and the polyester film surface facing the Byk Maci instrument. The sample was illuminated with d65 light offset from the mirror surface at 110 degrees using CIELab settings. At least five samples of the given coating were taken from different areas of the coating film.

[0153] 3.2 Application of a monochrome (straight shade) undercoat composition containing black pigment

[0154] The composition was applied to steel plates (T12M black and white plates, Leneta) using a 200-micron slit on a Byk scraper. Each plate and the resulting coating was flash-treated at 40°C for 10 minutes. Then, each plate was coated with a commercially available clear coat composition (from BASF Corporation Coatings Division, USA). 2K4) spray and bake at 130°C for 25 minutes.

[0155] The cured coating on the steel substrate was then analyzed using a Byk Maci spectrophotometer. The sample was placed on a mirror with the coating facing the mirror surface and the polyester film surface facing the Byk Maci instrument. The sample was illuminated with d65 light offset from the mirror surface at 110 degrees using CIELab settings. At least five samples of the given coating were taken from different areas of the coating film.

[0156] Tables 2 and 3 also present the results of cured coatings and multilayer coatings produced based on the coating compositions of the present invention and comparative coatings.

[0157] Table 2 clearly shows that the coatings of the present invention exhibit at least acceptable, but generally even good or excellent, transparency and therefore pigment distribution. On the other hand, the comparative system is unacceptable in this respect. For the black compositions and coatings, the systems of the present invention also show a significant reduction in the L(110°) value of the cured coating compared to the comparative system.

[0158] In summary, the data show that the dispersing ability of the reaction product / dispersant used in this invention is significantly better than that of the comparative dispersant (CP).

[0159] Table 2: Reaction products, transparent coating compositions containing blue pigment, corresponding cured coatings and their performance characteristics

[0160]

[0161]

[0162] Table 2 – Follow-up

[0163]

[0164] Table 3: Reaction products, coating compositions containing black pigment, corresponding cured coatings and their performance characteristics

[0165]

[0166] Table 3 – Subsequent

[0167]

[0168]

Claims

1. A coating composition comprising a pigment paste, wherein the pigment paste comprises an organic pigment and an aryl-modified branched reaction product (P) comprising in reacted form: (a) a core moiety which is polyhydroxy-functional, and (b) a shell moiety comprising polyalkylene oxide units and aromatic units, wherein the polyalkylene oxide units and the aromatic units are covalently linked to the core moiety via units comprising a functional group reactive towards hydroxyl groups.

2. The coating composition according to claim 1, wherein the shell moiety further comprises acid groups which are covalently linked to the core moiety via units comprising a functional group reactive towards hydroxyl groups.

3. The coating composition according to claim 1, wherein the functional group reactive towards hydroxyl groups is selected from the group consisting of carboxyl groups, cyclic carboxylic anhydride groups and isocyanate groups.

4. The coating composition according to claim 2, wherein the functional group reactive towards hydroxyl groups is selected from the group consisting of carboxyl groups, cyclic carboxylic anhydride groups and isocyanate groups.

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

6. The coating composition according to claim 2, wherein the aromatic units are attached via reaction of the hydroxyl groups of the core moiety with at least one aromatic or araliphatic carboxylic acid.

7. The coating composition according to claim 3, wherein the aromatic units are attached via reaction of the hydroxyl groups of the core moiety with at least one aromatic or araliphatic carboxylic acid.

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

9. The coating composition according to any one of claims 1 to 8, wherein the polyalkylene oxide units are attached via reaction of the hydroxyl groups of the core moiety with at least one component (e) having polyalkylene oxide units and isocyanate groups.

10. The coating composition according to any one of claims 1 to 8, wherein the polyalkylene oxide units are polypropylene oxide and / or polyethylene oxide and mixed copolymers thereof.

11. The coating composition according to claim 9, wherein the polyalkylene oxide units are polypropylene oxide and / or polyethylene oxide and mixed copolymers thereof.

12. The coating composition according to claim 11, wherein the polyalkylene oxide units are polyethylene oxide.

13. The coating composition according to any one of claims 1 to 8, wherein the reaction product (P) has an acid value of 10 to 60 mg KOH / g.

14. The coating composition according to claim 11 or 12, wherein the reaction product (P) has an acid value of 10 to 60 mg KOH / g.

15. The coating composition according to any one of claims 1 to 8, wherein the ratio of the reaction product (P) and the organic pigment in the pigment paste is at least 0.55 by weight.

16. The coating composition according to claim 14, wherein the ratio of the reaction product (P) and the organic pigment in the pigment paste is at least 0.55 by weight. ​ ​ 17. The coating composition according to any one of claims 1 to 8, wherein the pigment paste comprises 1 to 20 wt.-% of the reaction product (P), 2 to 40 wt.-% of the organic pigment, 40 to 90 wt.-% of water and 2 to 20 wt.-% of the organic solvent, in each case based on the total weight of the composition.

18. The coating composition according to claim 16, wherein the pigment paste comprises 1 to 20 wt.-% of the reaction product (P), 2 to 40 wt.-% of the organic pigment, 40 to 90 wt.-% of water and 2 to 20 wt.-% of the organic solvent, in each case based on the total weight of the composition.

19. The coating composition according to any one of claims 1 to 8, wherein the ratio of pigment solids to total solids of the coating composition is 0.05 to 0.

2.

20. The coating composition according to claim 18, wherein the ratio of pigment solids to total solids of the coating composition is 0.05 to 0.

2.

21. The coating composition according to any one of claims 1 to 8, wherein the coating composition contains a hydroxyl-functional acrylic polymer, a hydroxyl-functional polyester and / or a hydroxyl-functional polyurethane.

22. The coating composition according to claim 20, wherein the coating composition contains a hydroxyl-functional acrylic polymer, a hydroxyl-functional polyester and / or a hydroxyl-functional polyurethane.

23. The coating composition according to any one of claims 1 to 8, wherein the coating composition is aqueous.

24. The coating composition according to claim 22, wherein the coating composition is aqueous.

25. A method for producing a cured coating on a substrate, comprising (i) applying the coating composition according to any one of claims 1 to 24 to the substrate, (ii) forming a film from the applied coating composition, and (iii) curing the film applied according to step (ii).

26. The method according to claim 25, wherein between steps (ii) and (iii), a clear coating composition is applied to the film according to step (ii), and step (iii) further comprises curing the applied clear coating composition, which means that the base coat and the clear coat film are cured together to form a multilayer coating.

27. A coating or multilayer coating produced by the method according to claim 25 or 26.

Images