Lampblack pigment-containing electrodeposition coating composition

Abstract

The present invention provides a method for producing a cathodically depositable polymer (a) comprising: (a) a polymer having a number-based median primary particle size (d) of at least 50 nm and at most 200 nm; and (b) a carbon black pigment (b) having a number-based median primary particle size (d) of at least 50 nm and at most 200 nm. N、50% The present invention also relates to a method for at least partially coating a conductive substrate by cathodic electrodeposition coating comprising at least steps (1) to (5), including step (1) of at least partially immersing the conductive substrate in an electrodeposition coating bath containing the electrodeposition coating composition of the present invention, a conductive substrate at least partially coated with the baked electrodeposition coating composition of the present invention and / or a conductive substrate obtained by the method of the present invention, and a method for using the carbon black pigment (b) to improve corrosion protection and / or film build uniformity.

Description

[Technical Field]

[0001] The present invention provides an aqueous cathodically depositable electrodeposition coating composition comprising at least one cathodically depositable polymer (a) and at least one carbon black pigment (b), wherein the at least one carbon black pigment (b) has a number-based median primary particle diameter (d N、50% The present invention also relates to a coating composition in which the carbon black pigment (b) is a lamp black pigment having the formula (I). The present invention also relates to a method for at least partially coating a conductive substrate by cathodic electrodeposition coating, comprising at least steps (1) to (5), including step (1) of at least partially immersing the conductive substrate in an electrodeposition coating bath comprising the electrodeposition coating composition of the present invention; a conductive substrate at least partially coated with the baked electrodeposition coating composition of the present invention; and / or a conductive substrate obtainable by the method of the present invention. The present invention also relates to a method for using the carbon black pigment (b) to improve corrosion protection and / or film build uniformity. [Background technology]

[0002] Background of the Invention In the automotive field, metal parts used in production usually need to be protected from corrosion. The requirements regarding corrosion inhibition that must be achieved are quite stringent, especially since manufacturers often guarantee that rust will not puncture for many years. Such corrosion inhibition is usually achieved by coating the component or the substrate used to produce the part with at least one coat of paint suitable for that purpose.

[0003] To ensure the necessary corrosion inhibition, electrodeposition coatings are commonly applied to metal substrates. The substrates may be pretreated with phosphates and / or other types of treatments. Electrocoat coatings are polymer-based binders, optionally containing crosslinkers, pigments and / or fillers, and often additives. Generally, electrocoat materials are either anodically (anodically) or cathodically (cathodically) depositable. Anodic electrocoat coating compositions, particularly those containing metallic effect pigments, are disclosed, for example, in WO 2006 / 117189 A1. However, cathodically depositable materials are most important in industrial coatings, especially automotive finishes. In cathodic electrocoat coating, the substrate to be coated is immersed in an electrocoat bath and connected as the cathode. The bath contains a counter anode. The particles of the electrocoat material are stabilized by a positive charge and deposit at the cathode to form the coating. After deposition, the coated substrate is removed from the electrodeposition bath and the coating is baked, i.e., heat cured.

[0004] Cathodically depositable electrocoat materials are known from the prior art, for example from EP 1041125 A1, DE 19703869 A1 and WO 91 / 09917 A2. Furthermore, coating compositions which typically contain an effective corrosion-inhibiting amount of carbon pigments are disclosed in WO 2004 / 065498 A2.

[0005] Metal substrates used in the automotive industry that require corrosion protection typically include a variety of different metal substrates, such as bare steel, phosphate-treated steel, and / or steel substrates, which have been pretreated with at least one other pretreatment method. Furthermore, these different metal substrates often undergo additional or alternative mechanical pretreatment, such as sanding, depending on the desired surface characteristics. When applying an electrodeposition coating to a substrate surface, differences in the substrate's material / surface characteristics can lead to differences in the application process, since differences in the substrate's material / surface characteristics can result in differences in film build height. These differences in film build height are undesirable because subsequent coatings, such as primers, must compensate for and smooth these differences to prevent telegraphing across the entire painted surface of the vehicle. Such compensation and / or smoothing often requires costly post-processing steps and must be performed manually.

[0006] Therefore, it is necessary to be able to provide an electrodeposition coating that allows for a uniform film build when applied onto the optionally pretreated surface of a substrate, regardless of the substrate material used and / or the pretreatment method used to pretreat said substrate material, without compromising the corrosion protection properties. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] WO2006 / 117189A1 [Patent Document 2] EP1041125A1 [Patent Document 3] DE19703869A1 [Patent Document 4] WO91 / 09917A2 [Patent Document 5] WO2004 / 065498A2 Summary of the Invention [Problem to be solved by the invention]

[0008] assignment Therefore, one objective underlying the present invention is to provide an electrodeposition coating that allows for a uniform film build upon application to the surface of a variety of optionally pretreated metal substrates, regardless of the substrate and / or pretreatment method used. [Means for solving the problem]

[0009] Solution This object can be solved by the subject matter of the present application as well as by the preferred embodiments thereof disclosed herein, i.e. the subject matter described herein.

[0010] The first subject of the present invention is (a) at least one cathodically depositable polymer, and (b) at least one carbon black pigment An aqueous cathodically depositable electrodeposition coating composition comprising: The at least one carbon black pigment (b) has a number-based median primary particle size (d N , 50% ) is a lamp black pigment having the coating composition.

[0011] A further subject of the present invention is a method for at least partially coating an electrically conductive substrate by cathodic electrodeposition coating, comprising at least steps (1) to (5), namely: (1) at least partially immersing a conductive substrate in an electrodeposition coating bath containing the electrodeposition coating composition of the present invention; (2) connecting the substrate as a cathode; (3) The coating film obtained from the electrodeposition coating composition is subjected to a direct current Current depositing on a substrate using (4) removing the coated substrate from the electrocoating bath; and (5) A process of baking the coating film deposited on the substrate. The method includes:

[0012] A further subject of the present invention is an electrically conductive substrate at least partially coated with a baked electrodeposition coating composition according to the invention and / or an electrically conductive substrate obtainable by the process according to the invention.

[0013] A further subject of the present invention is the use of at least one carbon black pigment (b) as defined herein above and hereinafter for improving the corrosion protection of conductive substrates having baked coatings obtained from aqueous cathodically depositable electrodeposition coating compositions which, in addition to at least one carbon black pigment (b), comprise at least one cathodically depositable polymer (a), and / or for improving the homogeneity of the film build and / or for reducing mapping of coatings obtained from aqueous cathodically depositable electrodeposition coating compositions which, in addition to at least one carbon black pigment (b), comprise at least one cathodically depositable polymer (a).

[0014] It has been found that the electrodeposition coating composition of the present invention allows for uniform film build when applied to a variety of optionally pretreated substrate surfaces, regardless of the substrate material and / or any optional prior pretreatment. This is surprising. Accordingly, it has been found that when the electrodeposition coating composition of the present invention is applied to these substrates, such as bare steel and phosphate-treated steel substrates, undesirable film build deviations due to differences in the surface properties of the substrates are eliminated or at least significantly reduced. This was also unexpected. In particular, this unexpected technical effect has been found to be the result of the specific pigment (b) present in the coating composition. This is also surprising, since carbon black pigment is typically incorporated into electrodeposition coating compositions solely to impart the overall gray color of the resulting electrodeposition coating.

[0015] Furthermore, it has been surprisingly found that not only does it improve the uniformity of the film build, but it also improves the corrosion protection of the substrate, without adversely affecting other properties of the resulting electrodeposited film, such as surface roughness.

[0016] In particular, the above-mentioned advantages and technical effects are achieved when using the specific carbon black pigment (b) defined above, i.e., a carbon black pigment having a number-based median primary particle size (d N、50% It has been found that these advantages and effects are observed only when the lamp black pigment has a particle size of 1 / 2 or less. As is clear from the experimental section of this document, these advantages and effects cannot be achieved when using other carbon black pigments, such as furnace black pigments or lamp black pigments, which do not satisfy the number-based median primary particle size criteria defined above. DETAILED DESCRIPTION OF THE INVENTION

[0017] Detailed Description of the Invention The term "comprising" in the sense of the present invention, for example in connection with the electrodeposition coating composition of the present invention, preferably has the meaning of "consisting of." In connection with the electrodeposition coating composition of the present invention, in addition to components (a) and (b) and water, the composition may contain one or more of the further components specified below that are optionally contained in the electrodeposition coating composition of the present invention. All components may be present in each case in their preferred embodiments, as specified below.

[0018] Electrodeposition coating composition of the present invention The cathodically depositable aqueous electrodeposition coating composition of the present invention (hereinafter also referred to as the electrodeposition coating composition of the present invention) comprises at least components (a) and (b) and further water. As used herein, the terms "electrodeposition coating composition" and "electrodeposition coating composition" have the same meaning and are interchangeable.

[0019] The cathodically depositable aqueous electrodeposition coating compositions of the present invention are suitable for at least partially coating a conductive substrate with the electrodeposition coating composition, meaning that they are suitable for at least partial application to the substrate surface of the conductive substrate, such application leading to the electrodeposition coating film on the surface of the substrate.

[0020] The cathodically depositable electrodeposition coating composition of the present invention is aqueous. The term "aqueous" in connection with the electrodeposition coating composition of the present invention is understood for the purposes of the present invention to mean that water as a solvent and / or diluent is present as the major component of all solvents and / or diluents present in the electrodeposition coating composition, preferably in an amount of at least 35% by weight, based on the total weight of the electrodeposition coating composition of the present invention. However, organic solvents may also be present in smaller proportions, preferably less than 20% by weight.

[0021] The electrocoating composition of the present invention preferably comprises a water fraction of at least 40% by weight, more preferably at least 50% by weight, even more preferably at least 60% by weight, even more preferably at least 65% by weight, in particular at least 70% by weight, and most preferably at least 75% by weight (in each case based on the total weight of the electrocoating composition).

[0022] The electrodeposition coating composition of the present invention preferably contains an organic solvent fraction of less than 10% by weight, more preferably 0 to less than 10% by weight, very preferably 0 to less than 7.5% by weight, or even 0 to less than 5% by weight, or 0 to 2% by weight (in each case based on the total weight of the electrodeposition coating composition). Specific examples of such organic solvents include heterocyclic, aliphatic, or aromatic hydrocarbons, monohydric or polyhydric alcohols, especially methanol and / or ethanol, ethers, esters, ketones, and amides, such as N-methylpyrrolidone, N-ethylpyrrolidone, dimethylformamide, toluene, xylene, butanol, ethylene glycol, propylene glycol, and butyl glycol ethers, as well as their acetates, butyl diglycol, diethylene glycol dimethyl ether, cyclohexanone, methyl ethyl ketone, methyl isobutyl ketone, acetone, isophorone, or mixtures thereof.

[0023] The solids content of the electrodeposition coating composition of the present invention is preferably in the range of 5 to 35% by mass, more preferably 7.5 to 30% by mass, very preferably 10 to 27.5% by mass, particularly 12.5 to 25% by mass, and most preferably 15 to 22.5% by mass or 15 to 20% by mass (in each case based on the total mass of the electrodeposition coating composition). The solids content, in other words, the non-volatile fraction, is measured according to the method described below.

[0024] The electrodeposition coating composition of the present invention preferably has a pH in the range of 2.0 to 10.0, more preferably in the range of 2.5 to 9.5 or in the range of 2.5 to 9.0, very preferably in the range of 3.0 to 8.5 or in the range of 3.0 to 8.0, more preferably in the range of 2.5 to 7.5 or in the range of 3.5 to 7.0, particularly preferably in the range of 4.0 to 6.5, and most preferably in the range of 3.5 to 6.5 or in the range of 5.0 to 6.0.

[0025] The electrodeposition coating composition preferably contains component (a) in an amount ranging from 15 to 85% by weight, more preferably from 20 to 80% by weight, very preferably from 25 to 77.5% by weight, more particularly from 30 to 75% by weight or from 35 to 75% by weight, and most preferably from 40 to 70% by weight or from 45 to 70% by weight or from 50 to 70% by weight (in each case based on the total solids content of the electrodeposition coating composition). Alternatively, the electrodeposition coating composition of the present invention preferably contains component (a) in an amount ranging from 1 to 40% by weight, more preferably from 2.5 to 37.5% by weight, very preferably from 4 to 35% by weight, even more particularly from 5.5 to 32.5% by weight, and most preferably from 7 to 30% by weight or from 8 to 25% by weight (in each case based on the total weight of the electrodeposition coating composition).

[0026] The electrodeposition coating composition preferably comprises component (b) in an amount in the range of 0.005 to 4.0% by weight, more preferably 0.007 to 2.5% by weight, very preferably 0.010 to 1.5% by weight, even more especially 0.015 to 1.0% by weight, and most preferably 0.020 to 0.5% by weight or 0.025 to 0.1% by weight (in each case based on the total weight of the electrodeposition coating composition).

[0027] The electrodeposition coating composition preferably comprises component (b) in an amount in the range of 0.005 to 5.0% by weight, more preferably 0.060 to 4.0% by weight, very preferably 0.070 to 3.0% by weight, even more particularly 0.080 to 2.0% by weight, even more preferably 0.09 to 1.5% by weight, even more preferably 0.10 to 1.0% by weight, and most preferably 0.12 to 0.75% by weight or 0.13 to 0.5% by weight (in each case based on the total solids content of the electrodeposition coating composition).

[0028] When the electrodeposition coating composition of the present invention further comprises at least one crosslinker component (c), the component (c) is preferably present in an amount ranging from 5 to 45% by weight, more preferably from 6 to 42.5% by weight, very preferably from 7 to 40% by weight, more particularly preferably from 8 to 37.5% by weight or from 9 to 35% by weight, most preferably from 10 to 35% by weight, and particularly preferably from 15 to 35% by weight (in each case based on the total solids content of the electrodeposition coating composition). Alternatively, when the electrodeposition coating composition of the present invention further comprises at least one crosslinker component (c), the component (c) is preferably present in an amount ranging from 0.5 to 30% by weight, more preferably from 1 to 25% by weight, very preferably from 1.5 to 20% by weight, more particularly preferably from 2 to 17.5% by weight, most preferably from 2.5 to 15% by weight, and particularly preferably from 3 to 10% by weight (in each case based on the total weight of the electrodeposition coating composition).

[0029] The electrodeposition coating composition of the present invention preferably does not contain a component having an olefinically unsaturated double bond. More specifically, neither component (a) nor (c) of the electrodeposition coating material composition of the present invention contains an olefinically unsaturated double bond.

[0030] The proportions (mass %) of all components (a), (b) and water contained in the electrodeposition coating composition of the present invention, as well as the proportions of any further components that may additionally be present as component (c), add up to 100 mass % based on the total mass of the electrodeposition coating composition.

[0031] When component (c) is present, the relative weight ratio of components (a) and (c) to each other in the electrodeposition coating composition is preferably in the range of from 5:1 to 1.1:1, more preferably in the range of from 4.5:1 to 1.1:1, very preferably in the range of from 4:1 to 1.2:1, and even more particularly in the range of from 3:1 to 1.5:1.

[0032] Component (a) Component (a) is at least one cathodically depositable polymer, and preferably functions as at least one binder in the electrodeposition coating composition of the present invention. Component (a) may also function as a grinding resin, as described in more detail below.

[0033] Any kind of polymer is suitable as binder and therefore as component (a), as long as it is cathodically depositable. Preferred are poly(meth)acrylates, (meth)acrylate copolymers, and epoxide polymers.

[0034] Component (a) of the electrodeposition coating composition of the present invention preferably comprises and / or is at least one epoxide-amine adduct.

[0035] For the purposes of the present invention, the epoxide-amine adduct is a reaction product of at least one epoxy resin and at least one amine. The epoxy resin used is more particularly an epoxy resin based on bisphenol A and / or its derivatives. The amines reacted with the epoxy resin are primary and / or secondary amines or salts thereof and / or salts of tertiary amines.

[0036] The at least one epoxide-amine adduct used as component (a) is preferably a cationic resin, an epoxide-based resin, or an amine-modified resin. Methods for preparing such cationic resins, amine-modified resins, and epoxide-based resins are known and are described, for example, in DE 3518732, DE 3518770, EP 0004090, EP 0012463, EP 0961797B1, and EP 0505445B1. The cationic resins, epoxide-based resins, and amine-modified resins are understood to be the reaction products of at least one polyepoxide having two or more, e.g., three, epoxide groups with at least one amine, preferably at least one primary and / or secondary amine. Particularly suitable polyepoxides are polyglycidyl ethers of polyphenols prepared from polyphenols and epihalohydrins. The polyphenols used may be, in particular, bisphenol A and / or bisphenol F. Other suitable polyepoxides are, for example, polyglycyl ethers of polyhydric alcohols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene 1,2-glycol, propylene 1,4-glycol, 1,5-pentanediol, 1,2,6-hexanetriol, glycerol, and 2,2-bis(4-hydroxycyclohexyl)propane. The polyepoxide used may also be a modified polyepoxide. A modified polyepoxide is understood to be a polyepoxide in which a portion of the reactive functional groups has reacted with at least one modifying compound. Specific examples of such modified compounds include the following: i) compounds containing carboxyl groups, such as saturated or unsaturated monocarboxylic acids (e.g., benzoic acid, linseed oil fatty acid, 2-ethylhexanoic acid, versatic acid), aliphatic, cycloaliphatic and / or aromatic dicarboxylic acids of various chain lengths (e.g., adipic acid, sebacic acid, isophthalic acid, or dimer fatty acids), hydroxyalkyl carboxylic acids (e.g., lactic acid, dimethylolpropionic acid), and carboxyl-containing polyesters, or ii) compounds containing amino groups, for example diethylamine or ethylhexylamine, or diamines with secondary amino groups, for example N,N'-dialkylalkylenediamines such as dimethylethylenediamine, N,N'-dialkyl-polyoxyalkyleneamines such as N,N'-dimethylpolyoxypropylenediamine, cyanoalkylated alkylenediamines such as bis-N,N'-cyanoethylethylenediamine, cyanoalkylated polyoxyalkyleneamines such as bis-N,N'-cyanoethylpolyoxypropylenediamine, polyaminoamides such as Versamides, in particular diamines (for example hexamethylenediamine), polycarboxylic acids, in particular amino-terminated reaction products of dimeric fatty acids and monocarboxylic acids, more particularly fatty acids, or the reaction product of one mole of diaminohexane with two moles of monoglycidyl ethers or monoglycidyl esters, in particular the glycidyl ester of an α-branched fatty acid, for example Versatic acid, or iii) hydroxyl group-containing compounds, such as neopentyl glycol, bisethoxylated neopentyl glycol, neopentyl glycol hydroxypivalate, dimethylhydantoin-N,N'-diethanol, hexane-1,6-diol, hexane-2,5-diol, 1,4-bis(hydroxymethyl)cyclohexane, 1,1-isopropylidenebis(p-phenoxy)-2-propanol, trimethylolpropane, pentaerythritol, or amino alcohols such as triethanolamine, methyldiethanolamine, or hydroxyl group-containing alkyl ketimines such as aminomethylpropane-1,3-diol methylisobutylketimine or tris(hydroxymethyl)aminomethanecyclohexanone ketimine, as well as polyglycol ethers, polyester polyols, polyether polyols, polycaprolactone polyols, or polycaprolactam polyols of various functionalities and molecular weights, iv) Saturated or unsaturated fatty acid methyl esters esterified with the hydroxyl groups of epoxy resins in the presence of sodium methoxide.

[0037] Specific examples of amines that can be used to prepare component (a) include mono- and dialkylamines such as methylamine, ethylamine, propylamine, butylamine, dimethylamine, diethylamine, dipropylamine, and methylbutylamine; alkanolamines such as methylethanolamine or diethanolamine; and dialkylaminoalkylamines such as dimethylaminoethylamine, diethylaminopropylamine, and dimethylaminopropylamine. Amines that can be used may also contain other functional groups, provided that they do not interfere with the reaction between the amine and the epoxide groups of the optionally modified polyepoxide and do not cause gelation of the reaction mixture. It is preferable to use secondary amines. The charge required for dilution with water and electrodeposition can be generated by protonation with a water-soluble acid (e.g., boric acid, formic acid, acetic acid, lactic acid, etc.; preferably, acetic acid and / or formic acid). Another method for introducing cationic groups into the optionally modified polyepoxide is to react the epoxide groups of the polyepoxide with an amine salt.

[0038] The epoxide-amine adduct that can be used as component (a) is preferably a reaction product of a bisphenol A-based epoxy resin with a primary amine and / or a secondary amine or a salt thereof and / or a salt of a tertiary amine.

[0039] Ingredient (b) The electrodeposition coating composition of the present invention contains at least one carbon black pigment as component (b), and this carbon black pigment is a lamp black pigment.

[0040] The term "pigment" is known to those skilled in the art, for example from DIN 55943 (dated October 2001). "Pigments" in the sense of the present invention preferably refer to components in the form of powders or flakes that are substantially, preferably completely, insoluble in the medium surrounding them, such as, for example, the electrodeposition coating composition of the present invention. Pigments are preferably colorants and / or substances that can be used as pigments due to their magnetic, electric and / or electromagnetic properties. Pigments preferably differ from "fillers" in terms of their refractive index. In the case of pigments, the refractive index is 1.7 or higher.

[0041] Carbon black pigments are typically produced by the thermal decomposition of hydrocarbons (liquid and gaseous hydrocarbons) under controlled conditions, i.e., by an oxidative pyrolysis process, most commonly via incomplete combustion of the feedstock. The most common source for carbon black production is heavy hydrocarbon streams obtained from coal or crude oil processing, known as carbon black oil (CBO). CBO typically contains primarily polycyclic aromatic hydrocarbon feedstocks. Natural gas, coal tar distillates (carbochemical oils), or petroleum fractions produced by thermal cracking of naphtha or diesel, and residual oils (petrochemical oils) produced by catalytic cracking of olefins are the primary sources of this feedstock. Production methods vary depending on the arrangement of the heating and cracking stages. The resulting carbon black product (e.g., lamp black, gas black, or furnace black) is filtered from the off-gas generated during the production process. Production methods include the furnace, gas, lamp, and thermal black processes.

[0042] More than 98% of the world's annual carbon black production is achieved through the furnace black process. This process is continuous and uses liquid and gaseous hydrocarbons as feedstocks. The heated liquid feedstock is sprayed onto a heat source generated by the combustion of natural gas or fuel oil with preheated air. Because of the extremely high temperatures involved, the reaction is carried out in a refractory-lined furnace. After carbon black is formed, the process mixture is quenched by the injection of water, which also prevents unwanted secondary reactions. The carbon black-laden gas passes through a heat exchanger for further cooling while simultaneously heating the preheated air required for process combustion. The carbon black particles are separated from the gas stream using a bag filter. The gases produced by the reaction are flammable and are often burned in boilers to generate steam and / or electricity, or are otherwise combusted. Because the carbon black collected on the filter has a very low bulk density, it is typically pelletized or further densified for easier handling, depending on the application.

[0043] The gas black process uses vaporized oil as a feedstock. The oil is heated, and the resulting vapor is carried by hydrogen-rich gas through a tube equipped with multiple burners. Individual particles impinge on the surface of a water-cooled drum. Some of the carbon black produced is deposited on rollers, while the remainder enters a filter system. The two carbon black streams are then combined. Further processing is similar to that of the furnace black process. The thermal black process for producing carbon black is a semi-batch process in which natural gas is the most commonly used feedstock, although higher hydrocarbon oils can also be used. This process involves pyrolysis of the feedstock in a refractory-lined vessel, splitting the natural gas into carbon black and hydrogen.

[0044] Lamp black is a special type of carbon black produced by the incomplete combustion of carbon black oil, similar to the furnace black process, except that the combustion takes place in a large, open, shallow vessel. Lamp black is the oldest industrial-scale method of producing carbon black and is still in use today. Lamp black pigment (b) is produced by this process.

[0045] The electrodeposition coating composition of the present invention preferably does not contain furnace black pigment, gas black pigment, and / or thermal black pigment. Furthermore, the at least one pigment (b) is preferably the only lamp black carbon black pigment present in the electrodeposition coating composition of the present invention. In particular, the at least one pigment (b) is preferably the only carbon black pigment present in the electrodeposition coating composition of the present invention.

[0046] The at least one carbon black pigment (b) has a number-based median primary particle size (d N , 50% ) The number-based median particle diameter (d N、50% The term "d" is a parameter known to those skilled in the art. The characteristic variables denoted with a lower case "d" are percentiles (50%) of the cumulative distribution curve, with the 50% percentile corresponding to the median. The index "N" relates to the number-based distribution.

[0047] The at least one carbon black pigment (b) preferably has a number-based median primary particle size (d) of at least 75 nm and at most 150 nm, more preferably at least 80 nm and at most 120 nm, even more preferably at least 85 nm and at most 110 nm, in particular at least 90 nm and at most 105 nm. N , 50% )

[0048] Furthermore, the at least one carbon black pigment (b) preferably has an average primary particle size of at least 50 nm and at most 200 nm, more preferably at least 60 nm and at most 175 nm, even more preferably at least 70 nm and at most 160 nm, even more preferably at least 80 nm and at most 150 nm, even more preferably at least 85 nm and at most 140 nm, in particular at least 90 nm and at most 130 nm, and most preferably at least 95 nm and at most 125 nm.

[0049] The at least one carbon black pigment (b) preferably has a primary particle size in the range of 5 nm to 600 nm, with 5 nm being the smallest measured primary particle size and 600 nm being the largest measured primary particle size.

[0050] Number-based median primary particle diameter (d N , 50% For the purposes of the present invention, the average primary particle size and the primary particle size, particularly the minimum and maximum primary particle size, are determined by transmission electron microscopy (TEM), as described below in the "Methods" section.

[0051] The at least one carbon black pigment (b) preferably has a pH value in the range from greater than 6 to 10. Lamp black pigments suitable as component (b) are commercially available.

[0052] The at least one carbon black pigment (b) preferably does not contain more than 50 ppm, more preferably more than 30 ppm, even more preferably more than 20 ppm, in particular more than 10 ppm, and most preferably more than 4 ppm of sulfur in the water-soluble fraction obtained from the at least one carbon black pigment (b), as measured by ICP-OES in accordance with DIN EN ISO 11885:2009-09, as described below in the "Methods" section.

[0053] Component (b) is preferably incorporated into the electrodeposition coating composition in the form of a pigment paste. In addition to pigment (b), additional pigments and / or fillers different from pigment (b) can, and preferably do, be present in the pigment paste. Such pastes typically contain at least one polymer used as a grinding resin. Therefore, the electrodeposition coating composition of the present invention preferably contains at least one such polymer used as a grinding resin. It is also possible for the at least one polymer (a) used as a binder in the electrodeposition coating composition to additionally function as a grinding resin in the pigment paste. The grinding resin is preferably an epoxide-amine adduct, which may correspond to and / or be included in the definition of component (a) as outlined above. The polymer used as the grinding resin preferably has building blocks that interact with the pigment surface. Therefore, the grinding resin preferably has an emulsifier effect. Quaternary ammonium compounds can often be incorporated to improve the properties of the grinding resin. The pigment is preferably co-ground, i.e., ground with a grinding resin to form the pigment paste. Conventionally, grinding is performed using a standard mill. To produce the finished electrodeposition coating composition, this paste is mixed with the remaining components. The use of a pigment paste is advantageous because it increases the flexibility of the electrodeposition coating process, as the pigment and binder of the electrodeposition coating composition can be easily adjusted to suit the application requirements at any time through the amount of pigment paste.

[0054] When the electrodeposition coating composition of the present invention contains at least one polymer used as a pulverized resin that is different from polymer (a), the polymer is contained in the electrodeposition coating composition in an amount of preferably 0.5 to 10 mass %, more preferably 0.5 to 7.5 mass %, and very preferably 0.75 to 5 mass %, based on the total mass of the electrodeposition coating composition.

[0055] Preferably, the coating composition of the present invention is obtainable by mixing a pigment paste containing at least one carbon black pigment (b) with a mixture containing at least water and polymer (a).

[0056] When the at least one pigment (b) is formulated into a pigment paste (which may also contain one or more additional pigments and / or fillers different from pigment (b) as component (d)) and the pigment paste is used as a precursor for preparing the electrodeposition coating composition of the present invention, the pigment paste preferably contains component (b) in an amount ranging from 0.10 to 10.0% by weight, more preferably from 0.15 to 7.5% by weight, very preferably from 0.20 to 5.0% by weight, more particularly from 0.25 to 3.5% by weight, even more preferably from 0.30 to 2.0% by weight, even more preferably from 0.35 to 1.5% by weight, and most preferably from 0.35 to 1.0% by weight, based on the total weight of the pigment paste. Preferably, the at least one pigment (b) is the only carbon black pigment present in the pigment paste.

[0057] Optional component (c) At least one crosslinking agent may be present in the electrodeposition coating composition as component (c), selected from the group consisting of blocked polyisocyanates, free polyisocyanates, amino resins, and mixtures thereof, and component (c) is different from component (a).

[0058] The term "blocked polyisocyanate" is well known to those skilled in the art. A usable blocked polyisocyanate is a polyisocyanate having at least two isocyanate groups (a diisocyanate in the case of exactly two isocyanate groups), but preferably a polyisocyanate having more than two, for example, 3 to 5, isocyanate groups. Here, the isocyanate groups are reacted, and the resulting blocked polyisocyanate is stable at room temperature, i.e., 18 to 23°C, particularly with respect to hydroxyl groups and amino groups, such as primary and / or secondary amino groups, but reacts at elevated temperatures, for example, above 80°C, above 110°C, above 130°C, above 140°C, above 150°C, above 160°C, above 170°C, or above 180°C, with conversion and formation of urethane and / or urea bonds, respectively.

[0059] When preparing the blocked polyisocyanate, any organic polyisocyanate suitable for crosslinking can be used. Usable isocyanates are preferably (hetero)aliphatic, (hetero)alicyclic, (hetero)aromatic, or (hetero)aliphatic-(hetero)aromatic isocyanates. Suitable polyisocyanates are those containing 2 to 36, particularly 6 to 15, carbon atoms.Suitable specific examples include ethylene 1,2-ethylene diisocyanate, tetramethylene 1,4-diisocyanate, hexamethylene 1,6-diisocyanate (HDI), 2,2,4(2,4,4)-trimethylhexamethylene 1,6-diisocyanate (TMDI), diphenylmethane diisocyanate (MDI), 1,9-diisocyanato-5-methylnonane, 1,8-diisocyanato-2,4-dimethyloctane, dodecane 1,12-diisocyanate, ω,ω'-diisocyanatodipropyl ether, and cyclobutene 1,3-diisocyanate. cyclohexane 1,3- and 1,4-diisocyanate, 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate (isophorone diisocyanate, hereinafter IPDI), 1,4-diisocyanatomethyl-2,3.5,6-tetramethyl-cyclohexane, decahydro-8-methyl (1,4-methanonaphthalene-2 ​​(or 3), 5-ylenedimethylene diisocyanate, hexahydro-4,7-methanoindan-1 (or 2), 5 (or 6)-ylenedimethylene diisocyanate, hexahydro-4,7-methanoindan-1 ( or 2),5 (or 6)-ylene diisocyanate, hexahydrotolylene 2,4- and / or 2,6-diisocyanate (H6-TDI), toluene 2,4- and / or 2,6-diisocyanate (TDI), perhydrodiphenylmethane 2,4'-diisocyanate, perhydrodiphenylmethane 4,4'-diisocyanate (H12MDI), 4,4'-diisocyanato-3,3',5,5'-tetramethyldicyclohexylmethane, 4,4'-diisocyanato-2,2,3,3,5.5',6,6'-octamethyldicyclohexylmethane , ω,ω'-diisocyanato-1,4-diethylbenzene, 1,4-diisocyanatomethyl-2,3,5,6-tetramethylbenzene, 2-methyl-1,5-diisocyanatopentane (MPDI), 2-ethyl-1,4-diisocyanatobutane, 1,10-diisocyanatodecane, 1,5-diisocyanatohexane, 1,3-diisocyanatomethylcyclohexane, 1,4-diisocyanatomethylcyclohexane, 2,5(2,6)-bis(isocyanatomethyl)bicyclo[2.2.1]heptane (NBDI), and mixtures of these compounds.It is also possible to use polyisocyanates of higher isocyanate functionality, such as trimerized hexamethylene diisocyanate, trimerized isophorone diisocyanate, and more particularly the corresponding isocyanurates. Furthermore, mixtures of polyisocyanates can also be used.

[0060] For blocking the polyisocyanate, it is preferable to use a suitable aliphatic, alicyclic, or aromatic alkyl monoalcohol. Specific examples include aliphatic alcohols such as methyl, ethyl, chloroethyl, propyl, butyl, amyl, hexyl, heptyl, octyl, nonyl, 3,3,5-trimethylhexyl, decyl, and lauryl alcohol, alicyclic alcohols such as cyclopentanol and cyclohexanol, and aromatic alkyl alcohols such as phenylcarbinol and methylphenylcarbinol. Similarly, suitable diols, such as ethanediol, 1,2-propanediol, and 1,3-propanediol, and / or polyols, can also be used for blocking the polyisocyanate. Other suitable blocking agents include hydroxylamines such as ethanolamine, oximes such as methyl ethyl ketone oxime, acetone oxime, and cyclohexanone oxime, and amines such as dibutylamine and diisopropylamine.

[0061] Tris(alkoxycarbonylamino)-1,3,5-triazines (TACT) are also known to those skilled in the art. The use of tris(alkoxycarbonylamino)-1,3,5-triazines as crosslinkers in coating compositions is known. For example, DE 19712940 A1 describes the use of such crosslinkers in basecoat materials. U.S. Pat. No. 5,084,541 describes the preparation of corresponding compounds that can be used as component (c). For the purposes of the present invention, such triazines are encompassed by the term "blocked polyisocyanates."

[0062] Amino resins (aminoplast resins) are also known to those skilled in the art. The amino resin used is preferably a melamine resin, more specifically a melamine-formaldehyde resin, which is also known to those skilled in the art. However, it is preferred not to use an amino resin such as a melamine-formaldehyde resin as the crosslinking agent (c). Therefore, it is preferable that the electrodeposition coating composition of the present invention does not contain an amino resin such as a melamine-formaldehyde resin.

[0063] The electrodeposition coating composition of the present invention is preferably used as a one-pack (1K) coating composition, and therefore preferably does not contain free polyisocyanate.

[0064] Optional component (d) The electrodeposition coating composition of the present invention may also contain at least one pigment different from the at least one carbon black pigment used as component (b) and / or may contain at least one filler as optional component (d).

[0065] The term "filler" is known to those skilled in the art, for example from DIN 55943 (date: October 2001). For the purposes of the present invention, a "filler" is preferably a component that is substantially, preferably completely, insoluble in the application medium, such as the electrodeposition coating composition of the present invention, and is used in particular for extending purposes. A "filler" in the sense of the present invention preferably differs from a "pigment" in its refractive index, which for fillers is less than 1.7.

[0066] As optional component (d), conventional fillers known to those skilled in the art can be used. Examples of suitable fillers include kaolin, dolomite, calcite, chalk, calcium sulfate, barium sulfate, graphite, silicates such as magnesium silicate, especially corresponding phyllosilicates such as hectorite, bentonite, montmorillonite, talc and / or mica, silica, especially fumed silica, hydroxides such as aluminum hydroxide or magnesium hydroxide, or organic fillers such as textile fibers, cellulose fibers, polyethylene fibers or polymer powders. For further details, see Römpp Lexikon Lacke und Druckfarben, Georg Thieme Verlag, 1998, pp. 250ff. "Fillers".

[0067] As optional component (d), conventional pigments known to those skilled in the art can be used, as long as they are different from pigment (b). Specific examples of suitable pigments include inorganic and organic color pigments. Specific examples of suitable inorganic color pigments include white pigments such as titanium dioxide, white zinc, zinc sulfide, or lithopone; black pigments such as carbon black other than pigment (b) (although it is preferred not to use any other carbon black pigments other than pigment (b)), iron manganese black, or spinel black; chromatic pigments such as chromium oxide, chromium oxide hydrate green, cobalt green or ultramarine green, cobalt blue, ultramarine blue or manganese blue, ultramarine violet or cobalt violet and manganese violet, iron oxide red, cadmium sulfoselenide, molybdate red, or ultramarine red; brown iron oxide, mixed brown, spinel phase and corundum phase, or chrome orange; or yellow iron oxide, nickel titanium yellow, chromium titanium yellow, cadmium sulfide, cadmium zinc sulfide, chrome yellow, or bismuth vanadate. Further inorganic color pigments include silicon dioxide, aluminum oxide, aluminum oxide hydrate, especially boehmite, titanium dioxide, zirconium oxide, cerium oxide, and mixtures thereof.Specific examples of suitable organic color pigments include monoazo pigments, disazo pigments, anthraquinone pigments, benzimidazole pigments, quinoacridone pigments, quinophthalone pigments, diketopyrrolopyrrole pigments, dioxazine pigments, indanthrone pigments, isoindoline pigments, isoindolinone pigments, azomethine pigments, thioindigo pigments, metal complex pigments, perinone pigments, perylene pigments, phthalocyanine pigments, or aniline black.

[0068] Like component (b), component (d) is preferably incorporated into the electrodeposition coating composition in the form of a pigment paste and / or filler paste. It is possible and preferred to use a single pigment paste containing both pigment (b) and one or more additional pigment and / or filler component(s) (d) (different from pigment (b)). Such pastes typically contain at least one polymer used as a grinding resin. Therefore, it is preferred that at least one such polymer be present as a grinding resin in the electrodeposition coating composition of the present invention. It is also possible for the at least one polymer (a) used as a binder in the electrodeposition coating composition to additionally function as a grinding resin in the pigment paste. The grinding resin is preferably an epoxide-amine adduct, which may correspond to and / or be included in the definition of component (a) as outlined above. The polymer used as the grinding resin preferably has building blocks that interact with the pigment surface. Therefore, it is preferred that the grinding resin have an emulsifier effect. Quaternary ammonium compounds can often be incorporated to improve the properties of the grinding resin. The pigment is preferably ground with a grinding resin to form a pigment paste. To produce the finished electrodeposition coating composition, this paste is mixed with the remaining components. The use of a pigment paste is advantageous because it increases the flexibility of the electrodeposition coating process, as the pigment and binder of the electrodeposition coating composition can be easily adjusted to suit the application requirements through the amount of pigment paste.

[0069] Further optional ingredients The electrodeposition coating composition of the present invention may contain at least one catalyst, such as component (e), such as a metal-containing catalyst. However, in a preferred embodiment, the electrodeposition coating composition of the present invention does not contain a catalyst such as a metal-containing catalyst. The optional catalyst is preferably a bismuth-containing catalyst. Particularly preferred are bismuth-containing catalysts such as bismuth(III) oxide, basic bismuth(III) oxide, bismuth(III) hydroxide, bismuth(III) carbonate, bismuth(III) nitrate, bismuth(III) subnitrate (basic bismuth(III) nitrate), bismuth(III) salicylate and / or bismuth(III) subsalicylate (basic bismuth(III) salicylate), and mixtures thereof. Particularly preferred are water-insoluble bismuth-containing catalysts. Bismuth(III) subnitrate is even more preferred. The electrodeposition coating composition of the present invention preferably contains at least one bismuth-containing catalyst in an amount such that the bismuth (III) content (calculated as bismuth metal) is in the range of 10 ppm to 20,000 ppm based on the total mass of the electrodeposition coating composition of the present invention. The amount of bismuth calculated as metal can be determined by inductively coupled plasma-atomic emission spectroscopy (ICP-OES) in accordance with DIN EN ISO 11885 (dated September 2009).

[0070] Depending on the desired application, the electrodeposition coating composition of the present invention may also contain one or more optional components (f) of commonly employed additives. Component (f) is different from any of components (a) to (e). These additives are preferably selected from the group consisting of wetting agents, emulsifiers, dispersants, surface-active compounds such as surfactants, flow control aids, solubilizers, antifoaming agents, rheology aids, antioxidants, stabilizers, preferably heat stabilizers, process stabilizers, and UV and / or light stabilizers, softeners, plasticizers, and mixtures of the aforementioned additives. The content of the additives may vary widely depending on the intended use. The content of the additives is preferably in the range of 0.1 to 20.0% by weight, more preferably 0.1 to 15.0% by weight, very preferably 0.1 to 10.0% by weight, particularly preferably 0.1 to 5.0% by weight, and even more particularly 0.1 to 2.5% by weight, based on the total weight of the electrodeposition coating composition of the present invention.

[0071] Electrodeposition coating method A further subject of the present invention is a method for at least partially coating an electrically conductive substrate by cathodic electrodeposition coating, comprising at least steps (1) to (5), namely: (1) a step of at least partially immersing a conductive substrate in an electrodeposition coating bath containing the electrodeposition coating composition according to any one of claims 1 to 9; (2) connecting the substrate as a cathode; (3) The coating film obtained from the electrodeposition coating composition is subjected to a direct current Current depositing on a substrate using (4) removing the coated substrate from the electrocoating bath; and (5) A process of baking the coating film deposited on the substrate. The method includes:

[0072] All preferred embodiments described hereinabove in relation to the electrodeposition coating composition of the present invention are also preferred embodiments in relation to the aforementioned method of the present invention in which this electrodeposition coating composition is used to at least partially coat a conductive substrate by cathodic electrodeposition coating.

[0073] The method of the present invention is particularly suitable for the electrocoating of automobile bodies or parts thereof, including respective metal substrates. A preferred substrate is therefore an automobile body or part thereof.

[0074] All commonly used conductive substrates known to those skilled in the art are suitable for use in the present invention.The conductive substrate used in the present invention is preferably a metal substrate, more preferably selected from the group consisting of steel, preferably selected from the group consisting of bare steel, cold-rolled steel (CRS), hot-rolled steel, galvanized steel such as hot-dip galvanized steel (HDG), alloy galvanized steel (e.g., Galvalume, Galvannealed, or Galfan), and aluminized steel, aluminum, and magnesium, as well as Zn / Mg alloys and Zn / Ni alloys.A particularly suitable substrate is a body part or the entire body of a production automobile.

[0075] It is preferred that each conductive substrate is cleaned and / or degreased before being used in step (1) of the method of the present invention.

[0076] The conductive substrate used in accordance with the present invention is preferably a pretreated substrate, for example a substrate pretreated with at least one metal phosphate, such as zinc phosphate. This type of phosphating pretreatment is usually carried out after cleaning the substrate and before the substrate is electrocoated in step (1), and is a pretreatment step commonly used, particularly in the automotive industry. However, pretreatment methods other than phosphating are also possible, for example thin film pretreatments based on zirconium oxide.

[0077] During steps (1), (2), and (3) of the method of the present invention, the electrodeposition coating composition of the present invention is deposited on the cathode in the region of the substrate immersed in the bath in step (1). In step (2), the substrate is connected as the cathode, and a voltage is applied between the substrate and at least one counter electrode, either located within the electrodeposition bath or separate from it, for example, via an anion-exchange membrane permeable to anions. The counter electrode thus functions as the anode. When a current is passed between the anode and the cathode, a firmly adherent coating is deposited on the cathode, i.e., the immersed portion of the substrate. The applied voltage is preferably in the range of 50 to 500 volts. When steps (1), (2), and (3) of the method of the present invention are performed, the temperature of the electrodeposition coating bath is preferably in the range of 20 to 45°C.

[0078] The baking temperature in step (5) is preferably in the range of 120 to 210°C, more preferably 120 to 205°C, very preferably 120 to 200°C, more particularly preferably 125 to 195°C or 125 to 190°C, and most preferably 130 to 185°C or 140 to 180°C.

[0079] After step (5) of the method of the present invention is performed, one or more additional coating layers can be applied on the baked coating obtained after step (5). For example, a primer and / or filler can be applied, followed by a base coat and a clear coat.

[0080] Therefore, the method of the present invention comprises at least one further step (6), namely (6) applying at least one additional coating composition different from the composition applied in step (1) at least partially onto the baked coating obtained after step (5); It is preferred that the composition contains:

[0081] Base material A further subject of the present invention is an electrically conductive substrate at least partially coated with the inventive baked electrodeposition coating, which corresponds to the baked coating obtained after step (5) of the inventive method.

[0082] All preferred embodiments described hereinabove with respect to the electrodeposition coating composition of the present invention and the method of the present invention are also preferred embodiments with respect to the at least partially coated substrate of the present invention.

[0083] How to use A further subject of the present invention is the use of at least one carbon black pigment (b) as described hereinabove for improving the corrosion protection of an electrically conductive substrate having a baked coating obtained from an aqueous cathodically depositable electrodeposition coating composition which, in addition to at least one carbon black pigment (b), comprises at least one cathodically depositable polymer (a), and / or for improving the film build homogeneity and / or for reducing mapping of a coating obtained from an aqueous cathodically depositable electrodeposition coating composition which, in addition to at least one carbon black pigment (b), comprises at least one cathodically depositable polymer (a).

[0084] The aqueous cathodically depositable electrodeposition coating composition is preferably the aqueous cathodically depositable electrodeposition coating composition of the present invention.

[0085] All preferred embodiments described herein in relation to the electrodeposition coating composition of the invention, the method of the invention, and the at least partially coated substrate of the invention are also preferred embodiments in relation to the method of use of the invention described above.

[0086] method 1. Determination of Nonvolatile Fraction The non-volatile fraction (solids content or solids content) is determined in accordance with DIN EN ISO 3251 (dated June 2019). 1 g of sample is weighed into a pre-dried aluminum dish, which is then dried in a drying oven at 180 °C for 30 minutes, cooled in a desiccator, and reweighed. The residue relative to the total amount of sample used corresponds to the non-volatile fraction.

[0087] 2. Analysis of the Water-Soluble Fraction of Carbon Black Pigment Using ICP-OES The water-soluble fraction of carbon black pigments, such as the carbon black pigment (b) used in the present invention, was investigated using inductively coupled plasma-atomic emission spectroscopy (ICP-OES) according to DIN EN ISO 11885 (dated September 2009) to determine the amount of unwanted elements / ions, such as Na, K, Cl, S, and Si. Samples for ICP-OES measurements were prepared according to DIN 19529 (dated December 2015) as follows: 10 g of carbon black pigment was weighed into a 250 mL PE screw cap and mixed with 80 mL of deionized water. The conductivity of the deionized water was previously measured. The sample was then eluted for 24 hours on an overhead shaker at 22 rpm. 20 mL of the resulting suspension was centrifuged, and the aqueous fraction was purified using a 0.45 μm frit. The aqueous fraction was analyzed by ICP-OES. A SpectroBlue instrument from Spectro was used for ICP-OES measurements.

[0088] 3. Number-based median primary particle size of carbon black pigment The number-based median primary particle size, average primary particle size, minimum particle size, and maximum particle size are determined by transmission electron microscopy (TEM). A Tecnai G20 microscope and instrument from FEI are used for TEM measurements. TEM measurements are performed in bright-field imaging mode at 200 kV. The microscope magnification is calibrated according to ISO 29301:2010. The magnification is selected so that the smallest particles observed can be imaged on at least 10 pixels. Samples for TEM measurements are prepared as follows: A spatula tip of a carbon black pigment, such as the carbon black pigment (b) used in the present invention, is placed on a first microscope slide, followed by a drop of deionized water. The resulting mixture is rubbed and stretched using a second microscope slide. One slide is then removed, and the resulting thin film is transferred to a sample carrier. The sample carrier is a 20 nm-thick carbon foil mounted on a 3 mm copper net. The sample is then analyzed by TEM. The recorded TEM images are subjected to automated evaluation. The evaluation is performed using ImageJ-Plugin ParticleSizer Software, which was developed within the framework of NanoDefine.

[0089] 4. VDA Climate Change Test (DIN EN ISO11997-1:2018-01) This climate change test is used to determine the corrosion resistance of a coating applied to a substrate. The climate change test is carried out over a so-called 5-cycle or 10-cycle period.

[0090] Before carrying out the climatic test, a cut is made in the coating of the specimen to be tested with a knife down to the substrate. During the climatic test, the substrate corrodes along the cut, allowing the extent of undercoat corrosion of the specimen to be tested in accordance with DIN EN ISO 4628-8 (03-2013). As corrosion progresses, the coating is more or less penetrated during the test. The extent of corrosion (in mm) is an indicator of the corrosion resistance of the coating.

[0091] 5. Salt spray test The corrosion resistance of coatings is determined by a salt spray test. The salt spray test is carried out on the coated substrate in accordance with DIN EN ISO 9227 NSS (dated September 2012). The specimen to be examined is placed in a chamber where a mist is generated from a 5% sodium chloride solution with a controlled pH between 6.5 and 7.2 at a temperature of 35°C (continuously for 504 or 1008 hours). This mist deposits on the specimen to be examined, covering it with a corrosive saltwater film.

[0092] Prior to the salt spray test according to DIN EN ISO 9227 NSS, the coating of the specimen to be investigated is scored with a blade down to the substrate, so that the substrate corrodes along the score line during the DIN EN ISO 9227 NSS salt spray test, allowing the specimen to be investigated for the level of corrosive attack according to DIN EN ISO 4628-8 (03-2013). As a result of the corrosion progression, the coating is more or less eroded during the test. The degree of erosion (in mm) is an indicator of the corrosion resistance of the coating.

[0093] 7.Film build and mapping The film build is determined according to DIN ENISO 2178:2016-11. This method is also used to measure film build differences (mapping).

[0094] 8.Surface roughness The surface roughness is measured in accordance with DIN EN10049:2014-03. [Example]

[0095] The following examples further illustrate the present invention and should not be construed as limiting the scope of the invention.

[0096] 1. Pigment paste production 1.1. Pigment paste P1 used in the present invention The ingredients shown in Table 1a below were mixed together in the following order in a dissolver, then ground in a standard grinder to obtain the pigment paste P1 used in the present invention.

[0097] [Table 1]

[0098] As can be seen from Table 1c below in section 1.3, CB1 is the pigment used according to the invention. An epoxide-amine adduct was used as the grinding resin. All additives and other components present in P1 are commercially available products. The solids content of the pigment paste P1 is 66.6% by weight.

[0099] 1.2. Pigment pastes P2 to P4 used for comparison The pigment pastes used for comparison are prepared in the same manner as described in section 1.1, except that instead of the pigment CB1 used in the invention, pigments CB2 for P2, CB3 for P3 and CB4 for P4 are used.

[0100] The compositions of pigment pastes P2, P3 and P4 are summarized in Table 1b.

[0101] [Table 2]

[0102] As can be seen from Table 1c below in Section 1.3, CB2, CB3, and CB4 are carbon black pigments used in a method not according to the present invention. Epoxide-amine adducts were used as the grinding resin. All additives and other components present in P2 to P4 were commercially available. Except for the carbon black pigment, the same components as in Pigment Paste P1 were used. Pigment Paste P2 had a solids content of 66.3% by weight. Pigment Paste P3 had a solids content of 66.0% by weight. Pigment Paste P4 had a solids content of 67.3% by weight.

[0103] 1.3. As is clear from Table 1c below, CB1 is the pigment used in accordance with the present invention, while CB2 and CB3, whose number-based median primary particle diameters are less than 50 nm, are lamp black pigments used in a manner not in accordance with the present invention. CB4 is a furnace black pigment (Monarch (registered trademark) 120 manufactured by Cabot Corporation), whose number-based median primary particle diameter is less than 50 nm, and therefore is also a carbon black pigment used in a manner not in accordance with the present invention.

[0104] [Table 3]

[0105] 1.4. Further properties of pigments CB1 to CB4 are shown in Tables 1d and 1e.

[0106] [Table 4]

[0107] [Table 5]

[0108] 2. Preparation of electrodeposition coating composition 2.1. Preparation of the aqueous coating composition I1 of the present invention The components shown in Table 2a below were mixed together in the order shown to obtain electrodeposition coating I1 of the present invention.

[0109] [Table 6]

[0110] The aqueous dispersion of binder and crosslinker was a commercial product (CathoGuard® 800) available from BASF Coatings GmbH, Germany, had a solids content of 38% by weight, and contained an epoxide-amine adduct and a blocked polyisocyanate, which was different from the epoxide-amine adduct used as the grinding resin for preparing pigment paste P1.

[0111] 2.2. Preparation of comparative aqueous coating compositions C2 to C4 Comparative aqueous coating compositions are prepared in the same way as described in section 2.1, except that instead of the pigment paste P1 used according to the invention, pigment pastes P2, P3 and P4 are used.

[0112] The compositions of coating compositions C2 to C4 are summarized in Table 2b.

[0113] [Table 7]

[0114] The aqueous dispersion of binder and crosslinker was a commercial product (CathoGuard® 800) available from BASF Coatings GmbH, Germany, had a solids content of 38% by weight, and contained an epoxide-amine adduct and a blocked polyisocyanate. This epoxide-amine adduct was different from the epoxide-amine adduct used as the grinding resin for producing pigment pastes P2 to P4.

[0115] 3. Electrodeposition coating on the substrate The coating films obtained from electrodeposition coating compositions I1 and C2 to C4 are deposited on a cathode-connected test panel within 2 minutes at a deposition voltage of 200 to 380 V and a coating bath temperature of 28 to 36°C, and then baked at a substrate temperature of 150 to 190°C for 15 minutes.

[0116] Various substrates were used as test panels: substrates S1 (bare steel), S2 (steel substrate pretreated with a phosphating composition (Gardobond® GB26S 6800 OC)), S3 (galvanized steel substrate pretreated with a phosphating composition (Gardobond® GB26S 6800 OG)), and S4 (bare steel substrate pretreated with a thin film pretreatment (Oxsilan® 9831W OC)).

[0117] For the phosphate-treated substrates S2 and S3, a deposition voltage of 220-260 V and a coating bath temperature of 32°C were used. Baking was carried out in an oven for 25 minutes at an oven temperature of 175°C. For the substrates S1 and S4, a deposition voltage of 180-240 V and a coating bath temperature of 32°C were used. Baking was carried out in an oven for 25 minutes at an oven temperature of 175°C.

[0118] 4. Examination of the properties of the coated substrate 4.1.Film Build The film build of the coated substrates S1, S2 and S3 was measured.

[0119] The film build is determined in accordance with DIN EN ISO 2178:2016-11 by measuring the dry layer thickness of the electrocoatings obtained on the various substrates, the results of which are summarized in Table 4a.

[0120] [Table 8]

[0121] Mapping In a separate experiment, the mapping (film build difference (Δ)) observed on coated substrates S1 and S3 was investigated. The results are summarized in Table 4b. Identical and specific application conditions were selected for substrates S1 and S3 for each of compositions I1, C2, C3, and C4. The conditions were adjusted to achieve a film build of approximately 20 μm on S3, in order to allow a direct comparison as far as mapping development was concerned. The applications for each of substrates S1 and S3 were carried out consecutively.

[0122] [Table 9]

[0123] 4.3. Corrosion prevention (salt spray test) The coated substrates S1 (504 hours) and S4 (1008 hours) were subjected to a salt spray test (NSS), the results of which are summarized in Table 4c.

[0124] [Table 10]

[0125] 4.4. Corrosion Protection (VDA) The coated substrates S2 (10 cycles) and S4 (10 cycles) were subjected to the VDA test (VDA), the results of which are summarized in Table 4d.

[0126] [Table 11]

Claims

1. 1. An aqueous cathodically depositable electrodeposition coating composition comprising: (a) at least one cathodically depositable polymer, wherein at least one epoxide-amine adduct is present as said at least one cathodically depositable polymer (a); and (b) at least one carbon black pigment in an amount ranging from 0.005 to 4.0% by weight, based on the total weight of the electrodeposition coating composition; Including, The at least one carbon black pigment (b) has a number-based median primary particle size (d Ｎ , ５０％ ) is a lamp black pigment having The electrodeposition coating composition further comprises at least one pigment different from the at least one carbon black pigment (b) and / or at least one filler. A coating composition characterized by:

2. 2. The electrodeposition coating composition of claim 1, wherein the electrodeposition coating composition comprises component (a) in an amount ranging from 15 to 85% by weight (based on the total solids content of the electrodeposition coating composition).

3. 2. The electrodeposition coating composition according to claim 1, wherein the electrodeposition coating composition comprises component (a) in an amount ranging from 1 to 40% by weight (based on the total weight of the electrodeposition coating composition).

4. The at least one carbon black pigment (b) has a number-based median primary particle size (d Ｎ , ５０％ The coating composition according to any one of claims 1 to 3, characterized in that it comprises:

5. 5. The coating composition according to claim 1, wherein the at least one carbon black pigment (b) has an average primary particle size of at least 50 nm and at most 200 nm, preferably at least 75 nm and at most 150 nm.

6. 6. The coating composition according to claim 1, wherein the at least one carbon black pigment (b) has a primary particle size ranging from 5 nm to 600 nm.

7. 7. The coating composition according to claim 1, wherein the at least one carbon black pigment (b) does not contain more than 50 ppm of sulfur in the water-soluble fraction obtained from the coating composition, as measured by ICP-OES according to DIN EN ISO 11885:2009-09.

8. 8. A coating composition according to claim 1, characterized in that it is obtained by mixing a pigment paste comprising at least the at least one carbon black pigment (b) with a mixture comprising at least water and the polymer (a).

9. 9. The coating composition according to claim 1, wherein the at least one carbon black pigment (b) is the only carbon black pigment present in the electrodeposition coating composition.

10. 10. The coating composition according to claim 1, wherein the at least one carbon black pigment (b) is present in the electrodeposition coating composition in an amount ranging from 0.050 to 5.0% by weight, based on the total solids content of the electrodeposition coating composition.

11. 11. A coating composition according to any one of claims 1 to 10, characterized in that the at least one epoxide-amine adduct is present as at least one polymer (a) and is the reaction product of at least one epoxy resin based on bisphenol A with at least one primary amine and / or secondary amine and / or salts thereof and / or at least one salt of a tertiary amine.

12. 12. The coating composition according to claim 1, wherein at least one crosslinking agent is present in the electrodeposition coating composition as component (c), and is selected from the group consisting of blocked polyisocyanates, free polyisocyanates, amino resins, and mixtures thereof.

13. A method for at least partially coating a conductive substrate by cathodic electrodeposition coating, comprising at least steps (1) to (5), namely: (1) a step of at least partially immersing the conductive substrate in an electrodeposition coating bath containing the electrodeposition coating composition according to any one of claims 1 to 12; (2) connecting the substrate as a cathode; (3) depositing a coating film obtained from the electrodeposition coating composition on the substrate using a direct current; (4) removing the coated substrate from the electrocoating bath; and (5) A step of baking the coating film deposited on the substrate. A method comprising:

14. At least one further step (6), namely (6) applying at least one additional coating composition different from the composition applied in step (1) at least partially onto the baked coating obtained after step (5).

14. The method of claim 13, comprising:

15. A conductive substrate at least partially coated with the electrodeposition coating composition according to any one of claims 1 to 12 in a baked state.

16. 11. A method of using at least one carbon black pigment (b) according to any one of claims 1 to 10 for improving corrosion protection of an electrically conductive substrate having a baked coating obtained from an aqueous cathodically depositable electrodeposition coating composition which, in addition to the at least one carbon black pigment (b), comprises at least one cathodically depositable polymer (a), and / or for improving the homogeneity of the film build and / or for reducing mapping of a coating obtained from an aqueous cathodically depositable electrodeposition coating composition which, in addition to the at least one carbon black pigment (b), comprises at least one cathodically depositable polymer (a), comprising: at least one epoxide-amine adduct is present as said at least one cathodically depositable polymer (a); the carbon black pigment (b) is present in an amount ranging from 0.005 to 4.0% by weight based on the total weight of the electrodeposition coating composition; The electrodeposition coating composition further comprises at least one pigment different from the at least one carbon black pigment and / or at least one filler. method.

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