DE102018110594A1 - Method for wet-on-wet application of a multi-layer coating - Google Patents

Abstract

A wet-on-wet method of multilayer coating a substrate includes applying to the substrate to be coated a filler layer of organic solvent-based surfacer coating comprising at least one polyaspartic acid ester, at least one free isocyanate polyisocyanate crosslinking agent, at least one pigment and / or filler, and at least an organic solvent. The surfacer layer on the substrate to be coated is evaporated and a topcoat layer is applied to the surfacer layer.

Description

TECHNICAL AREA

The present invention relates to a wet-on-wet process for multi-layer coating of a substrate, which can be used in particular for the coating and refinishing of vehicle bodies and vehicle body parts.

BACKGROUND

Multilayer coatings consisting, for example, of a primer layer, a filler layer and a topcoat layer, wherein the topcoat layer comprises, for example, a basecoat and a clearcoat or is a pigmented one-coat topcoat layer, are typical vehicle coating and vehicle repair coating structures. The different layers of a multilayer coating are applied successively. Between each application step, a certain drying time is required until the next layer can be applied. The actual minimum drying time required before a previously applied coating can be overcoated depends on various factors such as physical drying and reactivity of the applied coating composition, the amount and type of solvent contained in the coating composition, the presence of curing catalysts, and external factors such as drying temperature and moisture during drying. In any case, prior to applying another coating layer to a previously applied coating layer, it is necessary that, on the one hand, the previously applied coating layer is sufficiently dried so that it does not mix or react with the other coating layer and its mechanical resistance is sufficient. On the other hand, especially for surfacer layers, it is also desirable that after drying, the mechanical resistance be such that it is still possible to remove defects in the dried layer before any further layer, such as a basecoat or a basecoat pigmented one-coat topcoat, is applied. Defects of the surfacer layer may also be visible after the application of another layer and thus degrade the visual appearance of the final coating. In other words, all of the above requirements affect the overall quality, and especially the visual appearance, of each topcoat layer that is applied to the previously applied filler layer.

In addition, productivity is an important issue in vehicle coating and vehicle repair coating. In particular, in the case where a multi-layer coating is applied, the drying times of each of the multiple coating layers should be as short as possible to shorten the total time needed to complete the coating process. Usually, as long as the coating process is not completed, the vehicle must remain within the spray equipment, such as a spray booth. Thus, the longer a vehicle occupies the sprayers on average, the fewer vehicles can be processed within a given time period.

A currently widely used method for applying multi-layer coatings, in particular in the field of vehicle refinishing (refinishing), are grinding processes. In a grinding process, after applying and at least partially drying the first layer, such as a filler layer, the first layer is surface treated by grinding. Such an abrasive surface treatment, for example, allows to compensate for unevenness of the coated surface, but may also be useful to improve intercoat adhesion to subsequently applied coating layers. However, the use of a sanding process firstly requires a more or less completely dried and / or cured coating layer and, on the other hand, generates sand dust which must be removed from the sanded surface in an additional, time-consuming cleaning step, which is both economically and environmentally undesirable. A wet-on-wet application process, as used for the application of multi-layer coatings, for example in post-processing applications, does not suffer from these procedural drawbacks because, in a wet-on-wet application process, no sanding of the first applied layer, such as a filler layer is performed. However, currently used coating compositions tend to require a considerably long drying time ("evaporation time") and / or the visual appearance of the final coating is not always satisfactory.

For example, currently used coating compositions for fillers and topcoats for wet-on-wet applications are special wet-on-wet two-component polyurethane compositions primarily formulated with acrylic and / or polyester resins. Such Filler compositions are often diluted in pigment volume concentration and adjusted to lower spray viscosities to obtain a smooth and smooth flow after application. The compositions may also use a favorable filler composition to give a good appearance after application of the topcoat. Since the reactivity for OH / NCO cured compositions is limited, longer air drying times of eg 15 to 30 minutes are necessary before removal of defects can be performed and a good and defect free appearance of the final topcoat layer can be obtained. In addition, surface defects such as blisters may occur, for example, when waterborne basecoats are applied too early to the previously applied filler layer.

An alternative current approach is to use modified two-component polyurethane abrasive fillers. In principle, the modified filler is based on a sanding filler which, for example, is converted to a wet-in-wet filler by adding a binder solution and / or by diluting the pigment volume concentration so as to increase spray performance and surface smoothness. However, these fillers do not meet the highest level of topcoat layer appearance of a subsequently applied topcoat layer, nor do they have high productivity.

It is also known in the art that the drying performance of standard two-component polyurethane wet-on-wet fillers can be accelerated by using high levels of cure catalysts, such as dibutyltin dilaurate (DBTL). Such an approach can lead to shorter air drying times, which makes it possible to perform a de-nibbing and over-coating already after short drying times. However, the appearance of the final topcoat of a subsequently applied topcoat layer is degraded and the pot life is shortened.

Thus, it is an object of the present invention to provide a wet on wet multilayer coating of a filler layer and a topcoat layer on a substrate that can be used in vehicle coating, such as OEM processes, as well as in vehicle repair coating and that offers high productivity while still providing the opportunity to remove defects in the surfacer layer prior to application of the topcoat layer while maintaining or even exceeding the appearance of the final topcoat layer, especially after finishing with a clearcoat layer and curing, as well maintain or even surpass the adhesion and corrosion protection properties of conventional filler compositions. It is a particular further object of the present invention to provide a process in which water-based topcoat compositions, such as a waterborne basecoat, can be applied to the filler layer. These objects are achieved by the method as defined in the claims and described in the following description.

SUMMARY OF THE INVENTION

1. (i) Auftragen auf dem zu beschichtenden Substrat einer Füllerschicht aus einer Füllerbeschichtungszusammensetzung auf organischer Lösungsmittelbasis, umfassend:
   1. A) zumindest einen Polyasparaginsäureester;
   2. B) zumindest ein Polyisocyanatvernetzungsmittel mit freien Isocyanatgruppen;
   3. C) zumindest ein Pigment und/oder Füllstoff; und
   4. D) zumindest ein organisches Lösungsmittel;
2. (ii) Abdunsten der Füllerschicht; und
3. (iii) Auftragen einer Decklackschicht auf die Füllerschicht.

The present invention relates to a wet-on-wet process for the multi-layer coating of a substrate, in particular for the multi-layer repair coating of a substrate, the process comprising the steps:

1. (i) coating on the substrate to be coated a filler layer of an organic solvent-based surfacer coating composition comprising:
   1. A) at least one polyaspartic acid ester;
   2. B) at least one polyisocyanate crosslinking agent having free isocyanate groups;
   3. C) at least one pigment and / or filler; and
   4. D) at least one organic solvent;
2. (ii) evaporating the surfacer layer; and
3. (iii) applying a topcoat layer to the filler layer.

1. A) zumindest einen Polyasparaginsäureester;
2. B) zumindest ein Polyisocyanatvernetzungsmittel mit freien Isocyanatgruppen;
3. C) zumindest ein Pigment und/oder Füllstoff; und
4. D) zumindest ein organisches Lösungsmittel

als Füller in einem Nass-in-Nass-Verfahren zur mehrschichtigen Beschichtung eines Substrats, insbesondere zur Mehrschichtreparaturbeschichtung eines Substrats.The present invention further relates to the use of a coating composition comprising:

1. A) at least one polyaspartic acid ester;
2. B) at least one polyisocyanate crosslinking agent having free isocyanate groups;
3. C) at least one pigment and / or filler; and
4. D) at least one organic solvent

as a filler in a wet-on-wet process for the multilayer coating of a substrate, in particular for the multi-layer repair coating of a substrate.

Surprisingly, it has been found that the disadvantages of the solutions of the prior art can be overcome if the method described above is carried out. Significantly increased productivity under air-drying conditions - without the need to apply heat - has been achieved without compromising the de-nibbing capabilities of the filler and the topcoat appearance of a topcoat layer which is subsequently applied to the filler layer. In particular, it has been found that in the case where a filler layer containing a polyaspartic acid ester, a polyisocyanate crosslinking agent having free isocyanate groups, at least one pigment and / or filler and at least one organic solvent is used as filler, it is possible to have high productivity with very good smoothing capabilities of the surfacer layer and a very good topcoat appearance of a topcoat layer applied to the surfacer layer.

DETAILED DESCRIPTION OF THE INVENTION

The invention will be explained in more detail below.

It will be understood that certain features, which are for the sake of clarity, described above and below in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features, which for the sake of brevity are described in the context of a single embodiment, may also be provided separately or in any sub-combination. In addition, references in the singular may also include plural (for example, "a" and "an" may refer to one or more), unless the context specifically indicates otherwise.

A wet-on-wet application method as described herein is specified in that after applying a first layer, i. the filler layer, and then evaporating the surfacer layer, the surfacer layer is not ground and in particular not completely ground, for example, with the aim of leveling the surface of the surfacer layer by removing any undesired structure therefrom. In other words, a wet-on-wet application process is not a grinding process. In addition, both the duration and conditions of evaporating the filler prior to application of a topcoat layer, such as temperature, air circulation or moisture, should not be limited by the term wet-on-wet application method.

A sanding process removes paint material and creates sand dust which must be removed from the sanded surface in an additional cleaning step. In addition, the color removed by grinding is typically measurable in μm film thickness and can be significant. Almost up to the entire layer structure can be abraded, especially if there is a roughness of the substrate to be compensated by the filler. The leveling of unevenness of the substrate and / or the removal of the structure of the applied filler by grinding is characteristic of a grinding process, but is not possible in a wet-on-wet or non-abrasive process. The latter method is therefore defined by the absence of the ability to remove structure and even out the unevenness of the substrate. In other words, in the context of the present invention, a wet-on-wet coating method and a non-grinding method should be understood as the same.

Smoothing is a carefully and mainly manually performed activity using a soft pad applied with very little pressure on the at least partially dried coating. In the present invention, smoothing is an optional step of the wet-on-wet application process which treats only local and usually very small areas of the coating. The aim of smoothing is to remove small surface defects of the surfacer coat before applying another topcoat since such a defect is still visible after application of the topcoat. These surface defects are usually caused by impurities such as foreign dust. Given the local application, the different objective as well as the Careful processing of the smoothing process is understood to mean that smoothing and grinding are completely different process steps. In addition, in contrast to full surface grinding of a filler, smoothing is not capable of improving interlayer adhesion to subsequently applied coating layers.

The term (meth) acrylic as used herein and hereinafter shall mean methacrylic and / or acrylic.

Unless otherwise indicated, all molecular weights (both number average and weight average molecular weights) herein are determined by GPC (gel permeation chromatography) using polystyrene as the standard and tetrahydrofuran as the liquid phase eluant.

Water-based or aqueous coating compositions are coating compositions in which water is used as a solvent or diluent when the coating composition is prepared and / or applied. For example, waterborne coating compositions may contain, for example, from about 30 to about 90 percent by weight of water, based on the total amount of the coating composition and optionally up to about 30 percent by weight, preferably below about 15 percent by weight organic solvents Total amount of coating composition.

Organic solvent-based coating compositions are coating compositions in which organic solvents are used as solvents or diluents when the coating composition is prepared and / or applied. For example, solvent-based coating compositions typically contain from about 20 to about 90 percent by weight of organic solvents, based on the total amount of the coating composition.

Fillers are defined as filled coating compositions which make contact with the topcoat layer. They create adhesion to the topcoat, help to protect against corrosion, fill in imperfections and prevent "shrinkage" of the topcoat and the emergence of substrate surface differences. Fillers are applied in coating layers of, for example, about 20 to about 400 microns (see, for example, definition in "Vehicle Refinishing", Fritz Sadowski).

The individual steps of the method considered here are explained in more detail below.

Substrates that can be coated with a multi-layer coating in the wet-on-wet process of the present invention may, in principle, be any substrate, such as a substrate. Metal, plastic, putty, e-coated metal (e-coat), steel, or any of these substrates with an existing coating such as an aged coating (old finish), and are preferably an e-coat, metal, or old paint. Suitable metal substrates are e.g. the metal substrates known in the automotive industry, such as iron, zinc, aluminum, magnesium, stainless steel or their alloys. The substrates are preferably vehicle bodies and vehicle body parts. For example, the substrate may be a metal substrate, which preferably comprises vehicle bodies or vehicle body parts.

In step (i) of the method under consideration, a filler layer of an organic solvent-based surfacer coating composition is applied to the substrate to be coated or repair-coated. The surfacer coating composition comprises A) at least one polyaspartic acid ester, B) at least one polyisocyanate crosslinking agent having free isocyanate groups, C) at least one pigment and / or filler, and D) at least one organic solvent.

The surfacer coating composition is a two-component coating composition, i. the mutually reactive components, namely the polyaspartic acid ester (A) and the polyisocyanate crosslinker (B), are stored separately from each other prior to use to prevent premature reaction. In general, component (A) and polyisocyanate component (B) can be mixed together just prior to application. The term "just before application" is well known to one skilled in the art. The period of time within which the ready-to-use coating composition may be prepared prior to actual use / application depends e.g. B. from the pot life of the coating composition. Compositions with very short pot life can be applied by two component spray guns wherein the reactive components are separately introduced into a static mixer and applied directly thereafter.

Component A) of the surfacer paint composition

wobei X eine n-wertige organische Gruppe, bevorzugt eine zweiwertige Kohlenwasserstoffgruppe darstellt, erhalten durch Entfernen der Aminogruppen von einem primären Polyamin oder Polyetheramin; R1 und R2 gleiche oder verschiedene organische Gruppen, die gegenüber Isocyanatgruppen inert sind, sind. R3, R4 und R5 sind gleich oder verschieden und stellen Wasserstoff oder organische Gruppen, die gegenüber Isocyanatgruppen inert sind, sind und n stellt eine ganze Zahl mit einem Wert von zumindest 2, bevorzugt 2 bis 4 und besonders bevorzugt 2 dar. X stellt bevorzugt eine zweiwertiges Kohlenwasserstoffgruppe, die durch Entfernen der Aminogruppen von den nachstehend spezifizierten primären Polyaminen und Polyetheraminen erhalten wird, dar und stellt besonders bevorzugt eine zweiwertige Kohlenwasserstoffgruppe, die durch Entfernen der Aminogruppen von den nachstehend angegebenen bevorzugten primären Polyaminen erhalten wird, dar. R1 und R2 sind gleiche oder verschiedene organische Gruppen und sind bevorzugt Methyl, Ethyl oder n-Butyl und R3, R4 und R5 sind bevorzugt Wasserstoff.The polyaspartic acid ester A) may be a compound of the formula (I) and is preferably a compound of the formula (I):

wherein X represents an n-valent organic group, preferably a divalent hydrocarbon group, obtained by removing the amino groups from a primary polyamine or polyetheramine; R1 and R2 are the same or different organic groups which are inert to isocyanate groups. R3, R4 and R5 are the same or different and are hydrogen or organic groups which are inert to isocyanate groups, and n represents an integer having a value of at least 2, preferably 2 to 4 and more preferably 2. X is preferably one divalent hydrocarbon group obtained by removing the amino groups of the below-specified primary polyamines and polyetheramines, and more preferably represents a divalent hydrocarbon group obtained by removing the amino groups from the preferred primary polyamines given below. R1 and R2 are the same or different organic groups and are preferably methyl, ethyl or n-butyl and R3, R4 and R5 are preferably hydrogen.

An organic group inert to isocyanate groups is an organic group which is resistant to isocyanate groups at a temperature of 150 ° C or less, e.g. 110 ° C or less inert. Polyaspartic acid esters of the formula (I) are prepared in a known manner by reacting the corresponding primary polyamines or polyetheramines of the formula X- (NH 2) n with optionally substituted maleic or fumaric acid esters of the formula R 1 OOC-CR 3 = CR 4 -COOR 2. X, R1, R2, R3, R4 and n have the meaning defined above for formula (I).

Primary polyamines or polyetheramines are preferred for preparing the polyaspartic esters because they provide a favorable solids / viscosity ratio to achieve a desired VOC of 4.5 lbs / gal (540 grams / liter) or less of the final filler formulation. A molar excess of the polyamines or polyetheramines can also be reacted with di- and polyisocyanates to produce amine-terminated ureas or polyether ureas or can be reacted with isocyanate-terminated polyesters, polycarbonates or polyethers selected from the corresponding polyester, polycarbonate or polyether di or polyols and subsequent conversion of the terminal amino groups to an aspartic acid ester by reaction with a maleic and / or fumaric acid ester.

Suitable primary polyamines include ethylenediamine, 1,2-diaminopropane, 1,4-diaminobutane, 1,3-diaminopentane, 1,6-diaminohexane, 2,5-diamino-2,5-dimethylhexane, 2,2,4- and 2 , 4,4-trimethyl-1,6-diaminohexane, 1,11-diaminoundecane, 1,12-diaminododecane, 1,3- and 1,4-cyclohexanediamine, 1-amino-3,3,5-trimethyl-5- aminomethylcyclohexane (IPDA), 2,4- and 2,6-hexahydrotoluenediamine, 2,4'- and 4,4'-diamino-dicyclohexylmethane (PACM) and 3,3'-dialkyl-4,4'-diaminodicyclohexylmethane such as 3 , 3'-dimethyl-4,4'-diaminodicyclohexylmethane and 3,3'-diethyl-4,4'-diaminodicyclohexylmethane, 2,4,4'-triamino-5-methyldicyclohexylmethane, 2-methyl-1,5-pentanediamine, 1,3- and 1,4-xylylenediamine and tetramethylxylylenediamine. Preferred primary polyamines are -IPDA, PACM, 3,3'-dialkyl-4,4'-diaminodicyclohexylmethane, such as 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane and 2-methyl-1,5-pentanediamine.

Suitable polyether polyamines are those having aliphatically bonded primary amino groups. The polyether polyamines may have a molecular weight of about 148 to about 6,000. Examples of suitable polyether are the products available under the trademark JEFFAMINE ^® from Huntsman.

Examples of optionally substituted maleic or fumaric acid esters useful in preparing the polyaspartic esters include dimethyl, diethyl, dibutyl (e.g., di-n-butyl, di-s-butyl, di-t-butyl ) Diamyl, di-2-ethylhexyl ester and mixed esters based on mixtures of the above groups and / or other alkyl groups; and the corresponding maleic and fumaric acid esters substituted at the 2 and / or 3 position with methyl. The dimethyl, diethyl and dibutyl esters of maleic acid are preferred, while the diethyl esters are particularly preferred.

Other diesters which may be used are those derived from cycloaliphatic, bicycloaliphatic and aromatic alcohols such as cyclohexanol, benzyl alcohol and isoborneol. Long chain mono alcohols such as ether alcohols may also be used, e.g. Example, the reaction products of monoalkyl, cycloalkyl and aryl monoalcohols with ethylene oxide, propylene oxide, butylene oxide, such as monobutyl glycol, monohexyl glycol, propylene glycol monobutyl ether.

The preparation of polyaspartic acid esters of the formula (I) from the above-mentioned starting materials may be carried out, for example, at a temperature of from 0 to about 150 ° C using the starting materials in proportions such that at least one, preferably one, olefinic double bond is present for each primary amino group is. Excess starting materials can be removed after the reaction by distillation. The reaction can be carried out solvent-free or in the presence of suitable organic solvents.

The polyaspartic acid ester may also be a chain-extended aspartate prepolymer, and is preferably a chain-extended aspartate prepolymer. It is understood that the chain-extended aspartate prepolymer is a reaction product of a mixture comprising at least one diaspartic ester and at least one amino-functional mono-aspartic acid ester. The preparation of a suitable chain-extended aspartate prepolymer is for example in WO 2015/130502 A1 described in detail.

For example, the at least one diaspartic acid ester is a compound of formula (I) as defined above wherein X, R1, R2, R3, R4, R5 and n are as defined above.

In one embodiment, the at least one diaspartic acid ester, preferably the compound of formula (I), is a reaction product of at least one dialkyl maleate and at least one primary diamine. Alternatively, the at least one diaspartic acid ester, preferably the compound of formula (I), is a reaction product of at least one dialkyl fumarate and at least one primary diamine.

worin Y eine zweiwertige organische Gruppe bedeutet, erhalten durch Entfernen einer Aminogruppe von einem primären Diamin; R1, R2, R6 und R7 gleiche oder verschiedene organische Gruppen, die gegenüber Isocyanatgruppen inert sind, sind und bevorzugt die gleichen organischen Gruppen sind und R3, R4, R5, R8, R9 und R10 gleich oder verschieden sind und bevorzugt die gleiche organische Gruppe sind und Wasserstoff oder organische Gruppen darstellen, die gegenüber Isocyanatgruppen inert sind.The at least one amino-functional monoaspartic acid ester is a compound of the formula (II) and / or (III):

wherein Y represents a divalent organic group obtained by removing an amino group from a primary diamine; R1, R2, R6 and R7 are the same or different organic groups opposite Isocyanate groups are inert, and are preferably the same organic groups and R3, R4, R5, R8, R9 and R10 are the same or different and are preferably the same organic group and represent hydrogen or organic groups which are inert to isocyanate groups.

For example, R1, R2, R6 and R7 are preferably methyl, ethyl or n-butyl, such as ethyl. In one embodiment, R3, R4, R5, R8, R9 and R10 are preferably the same and are hydrogen.

The at least one amino-functional monoaspartic acid ester, preferably the compound of the formula (II) and / or (III), is preferably a reaction product of at least one dialkyl maleate and / or dialkyl fumarate and at least one primary diamine. For example, the at least one amino-functional monoaspartic acid ester, preferably the compound of formula (II) and / or (III), is a reaction product of at least one dialkyl maleate or dialkyl fumarate and at least one primary diamine.

If the at least one diaspartic acid ester, preferably the compound of the formula (I) and / or the at least one amino-functional monoaspartic acid ester, preferably the compounds of the formula (II) and / or (III) is a reaction product of at least one dialkyl maleate and at least one primary diamine / are the at least one dialkyl maleate preferably selected from the group comprising dimethyl maleate, diethyl maleate, di-n-butyl maleate, di-isobutyl maleate, di-tert-butyl maleate, diamyl maleate, di-n-octyl maleate, dilauryl maleate, dicyclohexyl maleate, di-tert-butylcyclohexyl maleate and mixtures thereof. More preferably, the at least one dialkyl maleate is diethyl maleate.

Alternatively, when the at least one diaspartic acid ester, preferably the compound of formula (I), and / or the at least one amino functional monoaspartic acid ester, preferably the compound of formula (II) and / or (III) is a reaction product of at least one dialkyl fumarate and at least one A primary diamine is / are selected from the group comprising at least one fumarate, comprising dimethyl fumarate, diethyl fumarate, di-n-butyl fumarate, di-isobutyl fumarate, di-tert-butyl fumarate, diamyl fumarate, di-n-octyl fumarate, dilauryl fumarate, dicyclohexyl fumarate, di-n-butyl fumarate. tert-butylcyclohexyl fumarate and mixtures thereof.

Preferably, the at least one Diasparaginsäureester, preferably the compound of formula (I), and the at least one amino functional monoaspartic acid ester, preferably the compound of formula (II) and / or III), a reaction product of at least one dialkyl maleate and at least one primary diamine, wherein the at least one dialkyl maleate is selected from the group comprising dimethyl maleate, diethyl maleate, di-n-butyl maleate, di-iso-butyl maleate, di-tert-butyl maleate, and mixtures thereof. More preferably, the at least one dialkyl maleate is selected from the group comprising dimethyl maleate, diethyl maleate, di-n-butyl maleate, and mixtures thereof. Most preferably, the at least one dialkyl maleate is diethyl maleate.

It is understood that the at least one diaspartic acid ester, preferably the compound of the formula (I) and / or the at least one amino-functional monoaspartic acid ester, preferably the compound of the formula (II) and / or (III) is / are obtained by the at least one Dialkyl maleate and / or dialkyl fumarate as described above with at least one primary diamine is reacted.

The at least one primary diamine is preferably selected from any of the diamines contained in the group of primary polyamines as defined above in connection with the polyaspartic esters of formula (I) and mixtures thereof. Preferably, the at least one primary diamine is selected from the group comprising IPDA, PACM and 3,3'-dialkyl-4,4'-diaminodicyclohexylmethane, such as 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane and 3,3'- Diethyl 4,4'-diaminodicyclohexylmethane, 2-methyl-1,5-pentanediamine and mixtures thereof. More preferably, the at least one primary diamine is IPDA and / or PACM. Most preferably, the at least one primary diamine is IPDA.

If the polyaspartic acid ester A) is a chain-extended aspartate prepolymer, it is a further requirement that the mixture comprises the at least one diaspartic acid ester and the at least one amino-functional mono-aspartic acid ester such that the molar ratio between the at least one diaspartic ester, preferably the compound of the formula ( I), and the at least one amino-functional monoaspartic acid ester, preferably the compound of the formula (II) and / or III) of 99.5: 0.5 to 50:50 and preferably from 95: 5 to 60:40.

It is understood that the at least one diaspartic acid ester, preferably the compound of the formula (I) and / or the at least one amino-functional monoaspartic acid ester, preferably the compound of the formula (II) and / or (III), is preferably obtained by the at least one dialkyl maleate and / or Dialkyl fumarate and the at least one primary diamine in an equivalent ratio of dialkyl maleate and / or dialkyl fumarate to primary diamine from 2: 1 to 1: 4, preferably from 1: 1 to 1: 3, more preferably from 1.8: 1 to 2.2: 1 and most preferably about 2: 1.

The mixture of the at least one diaspartic acid ester, preferably the compound of the formula (I), and the at least one amino-functional monoaspartic acid ester, preferably the compound of the formula (II) and / or (III), is preferably prepared in a known manner by adding the corresponding at least one Dialkyl maleate and / or dialkyl fumarate is reacted with at least one primary diamine, for example at a temperature of 0 to 150 ° C using the starting materials in such proportions that the mixture containing the at least one diaspartic ester, preferably the compound of formula ( I), and the at least one amino-functional monoaspartic acid ester, preferably the compound of formula (II) and / or (III) comprises, is obtained. Excess starting materials can be removed after the reaction by distillation. The reaction can be carried out solvent-free or in the presence of suitable organic solvents.

When the polyaspartic acid ester A) is a chain-extended aspartate prepolymer, it is a further requirement that the chain-extended aspartate prepolymer be prepared by reacting the mixture comprising the at least one diaspartic ester, preferably the compound of formula (I), and the at least one amino-functional mono-aspartic acid ester , preferably the compound of the formula (II) and / or (III) as defined above, comprising obtained with at least one polyisocyanate.

The at least one polyisocyanate may be any type of organic polyisocyanates having aliphatically, cycloaliphatically, araliphatically and / or aromatically bound free isocyanate groups, and is preferably any type of organic polyisocyanate having cycloaliphatic-bonded free isocyanate groups. The at least one organic polyisocyanate, preferably at least one cycloaliphatic polyisocyanate, is preferably liquid at room temperature or becomes liquid by adding organic solvents.

In one embodiment of the present invention, the at least one polyisocyanate, preferably the at least one cycloaliphatic polyisocyanate, has an average NCO functionality of from 1.5 to 6.0, preferably from 1.8 to 4.0, and most preferably about 3, 0 on.

The at least one polyisocyanate which is suitable for preparing the chain-extended aspartate prepolymer is preferably selected from the group comprising 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (IPDI), 4,4'- Diisocyanatocyclohexylmethane, cyclotrimers and / or biurets of 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane, hexamethylene diisocyanate (HDI), 1-bis (isocyanatocyclohexyl) methane and their derivatives, 1,1,6,6 Tetramethylhexamethylene diisocyanate, p- or m-tetramethylxylylene diisocyanate, 2,2 ', 5-trimethylhexane diisocyanate and mixtures thereof and reaction products thereof. More preferably, the at least one polyisocyanate is IPDI or HDI and most preferred is IPDI.

It is clear that the chain-extended aspartate prepolymer is preferably obtained by reacting the mixture comprising the at least one diaspartic ester, preferably the compound of the formula (I), and the at least one amino-functional mono-aspartic acid ester, preferably the compound of the formula (II) and / or (III) comprises, with the at least one polyisocyanate, preferably the at least one cycloaliphatic polyisocyanate, in an equivalent ratio of NH and NH 2 groups in the mixture to NCO groups of the at least one polyisocyanate, preferably of the at least one cycloaliphatic polyisocyanate, of 2 , 0: 0.2 to 2.0: 1.8, preferably 2.0: 0.4 to 2.0: 1.4, and most preferably about 2.0: 0.6.

The chain-extended aspartate prepolymer is preferably prepared in a known manner by mixing the mixture comprising at least one diaspartic ester, preferably the compound of the formula (I), and at least one amino-functional monoaspartic acid ester, preferably the compound of the formula (II) and / or (III) in which at least one polyisocyanate, preferably the at least one cycloaliphatic polyisocyanate, is reacted, for example at a temperature of 0 to 150 ° C, using the starting materials in proportions such that the chain-extended aspartate prepolymer is obtained. Excess starting materials can be removed after the reaction by distillation. The reaction can be carried out solvent-free or in the presence of suitable organic solvents.

Accordingly, the chain-extended aspartate prepolymer is preferably a cycloaliphatic chain-extended aspartate prepolymer.

The chain-extended aspartate prepolymer may be further characterized by its equivalence ratio of aspartate groups to urea groups. Preferably, the chain-extended aspartate prepolymer comprises an equivalent ratio of aspartate groups to urea groups of from 10: 1 to 1: 0.9, more preferably from 5: 1 to 1: 0.9, and most preferably from about 2.0: 0.6.

When the polyaspartic acid ester A) is a chain-extended aspartate prepolymer, it is a requirement that the chain-extended aspartate prepolymer be free of isocyanate groups.

When the polyaspartic acid ester A) is a chain-extended aspartate prepolymer, a topcoat applied to the organic solvent-based surfacer coating composition has a still further improved topcoat appearance. When the polyaspartic acid ester A) is a chain-extended aspartate prepolymer, the organic solvent-based surfacer coating composition has improved pot life with a slower and less steep viscosity increase over time. When the polyaspartic ester A) is a chain-extended aspartate prepolymer, the coating composition is also less susceptible to yellowing over the storage time. Further, when the polyaspartic acid ester A) is a chain-extended aspartate prepolymer, a composition for storage comprising components A) and C) and / or D) has a particularly improved settling behavior over the storage time. In addition, a chain extended aspartate prepolymer can be made in a molecular weight distribution which complies with the official REACH (Chemical Registration, Evaluation, Authorization and Restriction) Polymer Definitions Regulation and can therefore be tailored, e.g. In terms of functionality per molecule, the network density of the applied filler, etc., without requiring a new expensive REACH registration.

Component B) of the surfacer paint composition

The surfacer coating composition also comprises a polyisocyanate crosslinking agent having free isocyanate groups. The polyisocyanates may be any number of organic polyisocyanates having aliphatically, cycloaliphatically, araliphatically and / or aromatically bound free isocyanate groups. The polyisocyanates are liquid at room temperature or become liquid by the addition of organic solvents. At 23 ° C, the polyisocyanates plus organic solvents generally have a viscosity of from about 1 to about 3500 mPas, preferably from about 5 to about 3000 mPas.

The polyisocyanate crosslinking agents may be used singly or in combination with each other. The polyisocyanate crosslinking agents are those commonly used in the paint industry. They are described extensively in the literature and are also commercially available. The isocyanate groups of the polyisocyanate crosslinker B) may be partially blocked. Low molecular weight compounds containing active hydrogen for blocking NCO groups are known. Examples of these blocking agents are aliphatic or cycloaliphatic alcohols, dialkylamino alcohols, oximes, lactams, imides, hydroxyalkyl esters and esters of malonic or acetoacetic acid.

Preferably, the surfacer coating composition comprises at least one aromatically-bound polyisocyanate crosslinking agent having free isocyanate groups having an average NCO functionality of from about 1.5 to about 6, preferably from about 2 to about 6. When at least one aromatic-bonded polyisocyanate crosslinking agent having free isocyanate groups is used, the total reactivity is the surfacer coating composition.

Examples of suitable polyisocyanates are so-called "lacquer polyisocyanates" based on hexamethylene diisocyanate (HDI), 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (IPDI) and / or bis (isocyanatocyclohexyl) methane and their derivatives. Typically, after production, the derivatives are freed from excess stock diisocyanate, preferably by distillation only to a residual level of less than about 0.5% by weight. Triisocyanates, such as triisocyanatononane, may also be used.

Sterically hindered polyisocyanates are also suitable. Examples of these are 1,1,6,6-tetramethylhexamethylene diisocyanate, 1,5-dibutylpentamethyl diisocyanate, p- or m-tetramethylxylylene diisocyanate and the appropriate hydrated homologs.

Examples of aromatically bound polyisocyanate crosslinking agents are based on 4,4'-biphenylene diisocyanate, toluene diisocyanate, tetramethylene xylene diisocyanate, 1,3-phenylene diisocyanate, 1,5-naphthalene diisocyanate, 4,4'-diisocyanatodiphenyl ether, triphenylmethane triisocyanate, 1,3,5-benzene triisocyanate and 2,4 , 6- Toluene triisocyanate. For example, a commercially available toluene diisocyanate Desmodur ^® L67 BA from Covestro.

In principle, diisocyanates can be converted by the usual methods to higher functional compounds, for example by trimerization or by reaction with water or polyols, such as trimethylolpropane or glycerol. The polyisocyanates can also be used in the form of isocyanate-modified resins or isocyanate-functional prepolymers. In general, the polyisocyanates may be isocyanurates, uretdione diisocyanates, biuret group-containing polyisocyanates, urethane group-containing polyisocyanates, allophanate group-containing polyisocyanates, isocyanurate and allophanate group-containing polyisocyanates, carbodiimide group-containing polyisocyanates, and polyisocyanates containing acyl urea groups.

Fillers coating composition

In addition to components A) and B), the surfacer coating composition C) contains at least one pigment and / or filler and D) at least one organic solvent. The organic solvents can come from the preparation of the binders or they can be added separately. They are organic solvents typically used for coating compositions and well known to those skilled in the art. The pigments and fillers can be any customary organic and / or inorganic coloring pigments and extenders, as are known to the person skilled in the art for the production of coating compositions, in particular for the production of filler compositions in the vehicle paint sector. Examples of pigments are titanium dioxide, micronised titanium dioxide, iron oxide pigments, carbon black, azo pigments, phthalocyanine pigments, quinacridone and pyrrolopyrrole pigments. Examples of fillers are silicon dioxide, aluminum silicate, aluminum oxide, carbonates, barium sulfate, kaolin and talc.

The surfacer coating compositions generally have a weight ratio of filler and pigments to binder solids of preferably about 4.0: 1.0 to about 1.0: 2.0, more preferably from about 2.5: 1.0 to about 1.0: 1.0. The pigment volume concentration (PVC) is, for example, in the range of about 20 to about 65% for surfacer coating compositions in general and in the range of about 20 to about 45% for wet-in-wet surfacer coating compositions. The PVC is the ratio of volume of pigments / fillers to the total volume of all nonvolatile components of the composition (including pigments / fillers, binders, additives, etc.) in percent.

The surfacer coating composition may also contain additives. The additives are the usual additives that can be used in the coating sector. Examples of such additives which are typical for use in surfacer coating compositions include trace, e.g. Based on (meth) acrylic homopolymers or polyether-modified polydimethylsiloxanes, anticrater agents, antifoaming agents, wetting agents, cure catalysts for the crosslinking reaction, dispersants, thickeners, emulsifiers and water scavengers. The additives are used in conventional amounts known to those skilled in the art.

In principle, the surfacer coating composition can still be adjusted to a spray viscosity with organic solvents before application. Also, another component can be used as a so-called diluent containing solvent and optionally other ingredients such as catalysts or other additives. All other components needed to make a useful surfacer composition, such as pigments, fillers, organic solvents, and additives, may each be in one of the two components, in both components, in the diluent of the two-component system, or in an additional component ( ie a converter).

Suitable catalysts are well known to those skilled in the art and may be selected from the groups of tin catalysts such as dibutyltin dilaurate (DBTL), amine catalysts such as 1,4-diazabicyclo [2.2.2] octane (DABCO) 1,8-diazabicyclo [ 5.4.0] undec-7-ene (DBU), 1,5-diazabicyclo [4,3,0] non-5-ene (DBN), 1,1,3,3-tetramethylguanidine (TMG), metal carboxylate Catalysts such as zinc octoate, zinc naphthenate, zinc or bismuth neodecanoate, organic acid catalysts such as acetic acid, oleic acid, benzoic acid or salicylic acid, OH-functional solvents, oligomers or polymers, and water. Other suitable catalysts are also in the WO 2014/106578 A1 described. One or more catalysts may be used.

The filler coating compositions may optionally be adjusted by varying amounts and combinations of catalysts to accommodate different temperature and humidity conditions during the application and annealing time of the filler.

In addition to components A) to D), the surfacer coating composition preferably comprises E) at least one additional binder component, for example crosslinkable binders having active hydrogen-containing functional groups. These binders may be monomeric, oligomeric and / or polymeric compounds having a number average molecular weight (Mn) of, for example, from about 500 to about 200,000 g / mole, preferably from about 1100 to about 100,000 g / mole. The active hydrogen functional groups may be hydroxyl and / or amino groups. The additional binder component E) is preferably selected from the group consisting of hydroxy-functional binders, amino-functional binders, amino alcohol-functional binders, polyaspartic ester binders other than A), aldimines and / or ketimines.

Binders with hydroxyl groups are, for example, the polyurethanes known to one skilled in polyurethane chemistry, (meth) acrylic copolymers, polyesters and polyethers which are used in the formulation of organic solvent-based coating compositions. They can be used individually or in combination with each other.

Examples of additional binders or reactive diluents with amino groups are, for example, oligomeric or polymeric blocked amines, such as oligomeric or polymeric ketimines and / or aldimines. Suitable ketimines and aldimines are described, for example, in COLOR & LACK 3/2004, pages 94-97, in US Pat DE4415778 or in EP05312249 disclosed. The surfacer coating composition used in the process contemplated herein may comprise from about 4 to about 40 weight percent solids, preferably from about 4 to about 20 weight percent solids, based on the total amount of surfacer coating composition, of the at least one polyaspartic acid ester. , The surfacer coating composition may also comprise up to about 20 weight percent solids, based on the total amount of surfacer coating composition, of the other crosslinkable binders, for example, about 1 to about 10 weight percent solids, based on the total amount of surfacer coating composition. In one embodiment, the surfacer coating composition may comprise from about 1 to about 20 weight percent solids, based on the total amount of surfacer coating composition, of aldimines and / or ketimines.

In the coating of vehicle bodies or vehicle body parts, in particular in vehicle bodywork or vehicle body part repair coating, coating compositions are preferably applied to the substrates by means of spraying. More preferably, in the process contemplated herein, the organic solvent based surfacer coating composition is applied using a manual pressure spray gun, a vacuum spray gun, airless and / or airmix techniques, pressure pot techniques, and / or non-manual automated techniques. These techniques are well known to those skilled in the art.

For example, the filler coating compositions are applied in a resulting dry film thickness of about 15 to about 400 microns.

In step (ii) of the method under consideration, the surface layer deposited in step (i) of the method under consideration is evaporated. The evaporation of a coating composition that has been applied to a substrate is generally well known to those skilled in the art and means that the coating composition that has been applied to a substrate remains as sprayed for a certain period of time, such that at least one of them, for example, has been sprayed can evaporate certain amount of solvent and start and / or proceed with any possible curing reaction of components of the coating composition. Normally, the evaporation is carried out at ambient temperatures of about 20 ° C to about 25 ° C, but may also be carried out at slightly elevated temperatures, for example up to about 40 ° C. Further, the flash can be performed at any humidity and is normally performed at ambient humidity, such as from about 10% to about 90%, and preferably from about 30% to about 80%. Evaporation may be performed in areas where vehicles or parts may be painted, and optionally in areas where the topcoat or basecoat and clearcoat are subsequently applied. This is preferably in a spray booth or any other suitable coating system with optionally controlled air circulation and / or controlled temperature.

Preferably, the fuser layer is flashed for 15 minutes or less, such as for 1-15 minutes, 2-15 minutes or 3-12 minutes, and more preferably for 5-10 minutes.

In step (iii) of the method under consideration, to provide a complete multi-layer coating, such as a multi-layer repair coating, the surfacer coat is overcoated with a topcoat after step (ii) of the process under consideration. The topcoat layer is preferably formed by applying a basecoat layer of a basecoat coating composition containing coloring and / or special effect pigments, preferably a waterborne basecoating composition, and a clearcoat layer of a clearcoat transparent coating composition to the basecoat layer, or is preferably applied by applying a single-coat topcoat layer of a single-stage topcoat coating composition , which contains coloring and / or special effect pigments, formed.

The basecoat composition contains the conventional ingredients of a water based pigmented basecoat coating composition such as coloring and / or special effect pigments, one or more binders, water and / or organic solvents, and optionally crosslinking agents and conventional coating additives.

After the basecoat coating composition has been applied, a clearcoat coating composition can be applied. The clearcoat coating composition may be applied to the basecoat layer either after drying or curing or after evaporation, for example at room temperature. Preferably, the clearcoat coating composition comprises a "two component" coating composition, i. comprises components which are reactive with each other, namely a binder component comprising active hydrogen and a polyisocyanate crosslinking agent. Preferred clearcoat coating compositions contain at least one hydroxyfunctional (meth) acrylate resin, optionally in combination with at least one hydroxy-functional oligomeric polyester and at least one polyisocyanate. The clearcoat compositions may contain conventional paint additives and organic solvents. Preferably, the clearcoat layer comprises at least one polyaspartic acid ester as defined, for example, by the above formula (I) or a chain-extended aspartate prepolymer as defined above, and at least one polyisocyanate crosslinking agent having free isocyanate groups, such as for component (B) above Filler coating composition, and the base coat layer optionally comprises at least one polyisocyanate crosslinking agent having free isocyanate groups, such as defined above for component (B) of the surfacer coating composition.

Alternatively, a one-step topcoat of a pigmented one-coat topcoat composition may be applied to the primer layer. The one-coat topcoat coating composition contains conventional lake pigments, for example, effect pigments and / or coloring pigments selected from white, colored and black pigments. Preferably, the one-coat topcoat coating composition comprises a "two component" coating composition, i. comprises components which are reactive with each other, namely, a binder component comprising active hydrogen and a polyisocyanate crosslinking agent.

The resulting two-coat or single-coat topcoats can be cured at room temperature or can be dried at higher temperatures, for example up to about 80 ° C, preferably at about 40 to about 60 ° C. The coating compositions are applied by conventional methods, preferably by spray application.

The method under consideration may be used in automotive and industrial painting, but particularly advantageously in vehicle repair coating as well as heavy vehicle coating and industrial coating.

When the substrate is a metal substrate, wherein the metal substrate preferably comprises vehicle bodies or vehicle body parts, the method considered here preferably comprises an additional step of pretreating the substrate to be coated with an acidic aqueous composition comprising a) phosphate ions and / or b) a water-soluble titanium. and / or c) zirconium compound and water, and optionally a step of subjecting the pretreated substrate to an evaporation phase. Such a pretreatment step is in EP 2862957 A1 described. The pretreatment of the metal substrate is performed prior to step (i) of the method under consideration.

The term "pretreatment composition" is intended to be used herein and hereinafter for the acidic aqueous composition as defined above.

In the optional step of pre-treating the metal substrate, the metal substrate to be coated or repair-coated is pretreated with the pretreatment composition. In particular, in the case of a repair coating method, the damaged area to be repair-coated, e.g. On a vehicle body or a vehicle body part, in a conventional manner, if necessary, before pretreating the metal substrate with the pretreatment composition. The damaged area and optionally also the adjacent transition area between the damaged area and the intact existing coating can be prepared for example by cleaning, grinding and cleaning again. The ground repair surface can be cleaned with conventional cleaning agents, such as low VOC surface cleaners or silicone removers. After the optional manufacturing step, the metal substrate is pretreated with the pretreatment composition containing a) phosphate ions and / or b) water-soluble titanium and / or zirconium compounds and c) water.

Preferably, the pretreatment composition comprises about 1 to about 25 weight percent, more preferably about 1 to about 16 weight percent, based on the total amount of the pretreatment composition, phosphate ion and / or about 0.3 to about 3 weight percent, more preferably from about 0.5% to about 1% by weight, based on the total amount of the pretreatment composition, of the at least one water-soluble titanium and / or zirconium compound, calculated as elemental titanium and zirconium. Phosphate ions can be present, for example, in the form of dissociated ortho-phosphoric acid and / or ortho-phosphoric acid salts, such as ammonium hydrogen phosphates.

Preferred water-soluble titanium and / or zirconium compounds are titanium or zirconium-containing complex fluoro acids, such as hexafluorotitanic acid and hexafluorozirconic acid, and fluorocomplexes of titanium or zirconium, such as hexafluorotitanates or hexafluorozirconates, such as di-potassium hexafluorozirconate, disodium hexafluorozirconate, ammonium hexafluorozirconate, magnesium hexafluorozirconate, di-lithium hexafluorozirconate and the analogues titanium complexes. The water-soluble titanium and / or zirconium compounds may be used alone or in combination with each other. Most preferred are the water-soluble titanium and / or zirconium compounds selected from hexafluorotitanic acid, hexafluorozirconic acid or a combination of both.

In an exemplary embodiment, the pretreatment composition has a pH of <7, preferably from about 1 to about 4.

The pretreatment composition may contain from about 30 to about 99 weight percent water.

The pretreatment composition may further contain additional ingredients, for example, compounds which act as sources of free fluoride, such as hydrofluoric acid, H2SiF6 and KF, oxidizing agents or accelerators, such as H2O2, HNO2, HNO3 and HClO4, additional metal ions, such as Zn (II), Mn (II) and Ni (II), and organic solvents such as butylglycol. Although not preferred, Cr6 + ions may also be present in the pretreatment composition. Examples of additional ingredients are in EP 1571237 . DE 10322446 and DE 10322446 described.

The phosphate ions and the water-soluble titanium and / or zirconium compound may be referred to as active ingredients of the pretreatment composition. The pretreatment composition may contain as the active ingredient the phosphate ions alone or the water-soluble titanium and / or zirconium compound alone or a combination of both. In one embodiment, the pretreatment composition includes phosphoric acid, in another embodiment, the pretreatment composition contains hexafluorotitan and / or hexafluorozirconic acid, and in yet another embodiment, the pretreatment composition comprises a mixture of phosphoric acid and hexafluorotitanic acid and / or hexafluorozirconic acid. Preferably, the pretreatment composition comprises phosphoric acid.

The pretreatment composition can be applied in a variety of ways. One option is to apply by spraying. Another possibility is to apply the pre-treatment composition by wiping, e.g. B. with a soaked with the pretreatment composition cloth. Preferably, the acidic composition is applied by wiping, more preferably by wiping with a cloth impregnated with the acidic aqueous solution. After applying the Pretreatment composition, a metal oxide conversion layer is formed on the metal substrate surface. Typically, the metal oxide conversion layer is very thin and has a layer thickness of <1 μm.

Suitable wipes, which are used for wiping, for example, those available under the trade name Sontara ^® from DuPont, or other cleaning cloths, which are discarded after use.

Suitable pretreatment compositions are also commercially available, for example under the trade name of Cromax 5717S ^® Refinish (phosphoric acid-based). Suitable wipes that are impregnated with the pretreatment composition, are also available, for example under the trade name Cromax ^® PS1800 Metal Pretreatment Wipes of axalta Coating Systems GmbH & Co. KG in the trade.

After the pretreatment of the metal substrate with the pretreatment composition, an evaporation phase is preferably provided to allow the solution to form the metal oxide conversion layer and to vaporize water and optional organic solvents. For example, an evaporation phase of about 1 to about 2 minutes may be provided at about 20 to about 23 ° C. The evaporation can be accelerated with warm air. Therefore, the total time required to apply the pretreatment composition and to flash off can range from about 3 minutes to about 5 minutes. A rinse step with water or other specific surface post-treatment or passivation solutions may be included, which may help to further improve the adhesion and corrosion protection of the paint system. Specific solutions include products that are commercially available from Cromax ^® Refinish under the product name 5718S.

The method considered here will be explained in more detail with reference to the following examples. All parts and percentages are by weight unless otherwise stated.

Examples

Inventive Examples (IE) 1: Preparation of surfacer coating compositions

Filler coating compositions IE 1.1 and IE 1.2 were prepared with the ingredients shown in Table 1. Table 1 Component 1 IE 1.1 IE 1.2 POLYA PARTIC ACID ESTERS (1) 24.1 POLYA PARTIC ACID ESTERS (2) 13.8 SOLVENT MIXTURE (3) 6.1 IRON OXIDE BLACK 0.8 0.8 TiO ₂ 7.6 7.5 BARIUM SULPHATE 15.2 15.1 TALK 2.5 2.5 KAOLIN 4.6 4.6 ZINC PHOSPHATE 4.0 4.0 Additions after dispersion step SOLVENT MIXTURE (3) 11.7 6.8 Component 2 POLYISOCYANATE HARDENERS (4) 29.5 38.8 TOTAL 100.0 100.0 (1) Inventive Example 3 (IE3) WO 2015130502 A1 (2) Desmophen ^® NH 1420 by Covestro (3) 1/1/1 mixture of butyl acetate, methoxypropyl acetate and xylene (4) Desmodur ^® L67 BA / Desmodur ^® N 3900 (both from Covestro) / butyl acetate / ethyl acetate: 22.2 / 16.5 / 29.5 / 31.8 (wt .-%)

The two compositions in Table 1 are formulations without additives, additional additional reactive or non-reactive components. Both formulations have the same formulation parameters, namely the NCO / NH stoichiometry (1.1), the pigment volume concentration (30%) and the theoretical volatile organic compounds according to EU-VOC legislation (525 g / L) and are therefore comparable. These formulations achieve the superior combination of fast overcoating, early smoothing and high-end topcoat appearance.

Inventive Examples (IE) 2: Ready-to-use surfacer coating compositions blended from commercially available products. Table 2: IE 2.1 IE2.2 ink pen SH5500 SH5500 * (NH1420) clearcoat SH8800 SH8800 Harder SH3550 SH3550 thinner SH3380 SH3380 Mixture by weight 100/6/60/10 100/6/70/5 SH5500: Permasolid ^® HS Speed filler 5500 SH8800: Permasolid ^® HS Speed Klarlach 8800 SH3550: Permasolid ^® Hardener 3550 SH3380: Permacron ^® Verdünnner 3380

The SH5500 formulation in IE2.1 is commercially available and is based on a chain-extended aspartate. SH5500 * is a modified SH5500 formulation, wherein the chain-aspartate was changed to the non-chain-extended Desmophen ^® NH1420 of Covestro so that in the ready-mix formulation parameters (stoichiometry, pigment volume concentration and volume solids) are not changed. These formulations are therefore comparable.

Comparative Examples 3 (CE 3): Commercially available filler compositions currently used in wet-on-wet application processes. Table 3: CE 3.1 CE 3.2 CE 3.3 CE 3.4 ink pen PS1064 NS2602 Sikkens ^® Autofüller rapid Glasurit ^® 285-31 Harder XK205 XK205 Autofüller rapid hardener 929-56 thinner AZ9032 XB383 Autofüller rapid non-abrasive hardener 523-15 Mixture by weight 100/17/23 100/16/19 Mix by volume 3/1/2 3/1/1 Version Technical Data Sheet (TDS) EN PS106x-4 EN NS206x-7 EU.3.2.28, 285-31 02/16 12/7/16 12/15/16 07/31/2015 523-15 01/16 PS1064: Cromax ^® Pro Filler PS1064 XK205: Cromax ^® AR7305 / activator XK205 AZ9032: Cromax ^® AZ9032 wet-on-wet converter NS2602: Cromax ^® NS2602 non-abrasive primer filler XB383: Cromax ^® Thinner XB383 285-31: Glasurit ^® HS VOC non-abrasive filler 285-31 929-56: Glasurit ^® hardener 929-56 523-15: Glasurit ^® Racing Additive 523-15

CE 3.1 and CE 3.2 are surfacer coating compositions commercially available from Axalta Coating Systems GmbH & Co. KG and widely used in body refinish. These surfacer coating compositions can also be used for the first OEM coating of commercial vehicles.

The composition of CE 3.1 is based on a two-component polyurethane abrasive filler to which the binder solution AZ9032 ("thinner or converter") is added to wet the original two-component polyurethane abrasive filler into a wet-on-wet filler by diluting the pigment volume concentration and Improve spray performance and surface smoothing. The filler PS1064 used in CE 3.1 contains no polyaspartic acid ester component.

CE 3.2 is a widely used two-pack, productive polyurethane filler that recoats after 15 minutes of air drying with good wet-on-wet application properties and long pot life. In addition, it can be applied to bare metal without the use of primer. The filler NS2602 used in CE 3.2 contains no polyaspartic acid ester component.

CE 3.3 is an isocyanate-free, high-productivity filler that can be overcoated after 15 minutes of air drying and is based on special acrylic binders in the base material and blocked high molecular weight polyamines in the activator.

CE 3.4 is a very productive two-component polyurethane wet-in-wet filler with a recommended flash-off time of 10 minutes. The chemical crosslinking is accelerated by high amounts of DBTL catalyst.

After mixing all the components of the compositions of IE 1, IE 2 and CE 3, the viscosities of the resulting mixtures in an Iso-3 cup after DIN EN ISO 2431 and in a din-4 cup DIN 53211 measured. Pot life was measured as the viscosity increase at 15 minute time intervals in a din-4 beaker. Table 4: Pot life of Examples 1-3 example IE 1.1 IE 1.2 IE 2.1 IE 2.2 CE 3.1 CE 3.2 CE 3.3 CE 3.4 Mixed viscosity ISO3 cup [s] 59 48 53 48 79 nm * nm * nm * Mixed viscosity DIN4 cup [s] 13.5 12.5 13 12.5 17 20 22 21.5 15 minutes 16 14 14 13 18 21 24 29 30 minutes 19 16.5 15.5 14 19 23 27 75 45 minutes 25 21 17 15 19 23 30 nm * 60 minutes 31 27 18 16 20 26 34 75 minutes 47 39 20 17 22 29 39 90 minutes 69 65 22 18 23 31 46 * not measurable

Higher spray viscosities at the time of application of the filler result in more film structure after application. Any increased film structure is still visible after application of the topcoat and results in a weaker topcoat appearance. A slow increase in viscosity after mixing of all components is therefore desirable.

Example 4: Application of the ready-to-use compositions of IE 1, IE 2 and CE 3 in combination with a water-based basecoat

For the coating method 30x60 cm GARDOBOND ^® 26S / 60 / OC steel sheets Chemetal were coated with electrocoat AquaEC 3000 from axalta Coating Systems GmbH & Co. KG (hereinafter referred to as E-coated steel sheets) by polishing and cleaning in accordance with the typical manufacturing process, used by a person skilled in the art.

For the compositions of IE 1 IE 2 and GARDOBOND ^® OMBS 35 defatted 10 were additionally x 20 cm steel panels Chemetal for the coating process by grinding and cleaning according to the typical manufacturing process, which are known to those skilled prepared. Cromax ^® PS1800 metal pretreatment cloths & the axalta Coatings Systems GmbH Co. KG are commercially available, have been applied in accordance with the technical data sheet and used. These plates are hereinafter referred to as "pretreated steel plates". Comparative Examples 3 were not applied to these pretreated steel sheets and tested because such multi-layer coating methods are not recommended in the respective technical data sheets of the market references.

Ready-to-use surfacer coating compositions were blended according to Table 2 and Table 3 and coated at a temperature of 22 ° C and 45% relative humidity on the substrates with a Sata RP 5000-1.3 mm Nozzle Spray Gun in a complete coating followed by a light coating (1.5 coats).

All primer-surfacer compositions were coated with a commercial water-based repair basecoat (Permahyd Hi-Tec Base Coat 480 in RAL5010 from Spies Hecker) and a solvent-based repair clearcoat (Permasolid HS Clearcoat 8055 from Spies Hecker) after 5 minutes of annealing at 22 ° C and 45% relative humidity painted over. In addition, in separate experiments, the surfacer coating compositions of Examples 3.1-3.4 were overcoated with the same basecoat and clearcoat as above after the minimum flashoff times recommended in the respective technical data sheets of these fillers, even at 22 ° C and 45% relative humidity. After clearcoat application, the paint systems were baked at 60 ° C for 30 minutes. The appearance of the paint systems was measured 24 hours after curing and storage of the panels at ambient temperature with a Byk Gardner Wave-Scan Dual (catalog number 4840). Table 5: Results of the wet-on-wet application process with water-based basecoat and solvent-based clearcoat on the E-coated steel sheets and the pretreated steel sheets: Inventive example evaporated for 5 minutes Market examples 5 minutes evaporated Market references to TDS evaporated example IE IE IE IE CE CE CE CE CE CE CE CE 1.1 1.2 2.1 2.2 3.1 3.2 3.3 3.4 3.1 3.2 3.3 3.4 coatings 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1 1.5 1 1.5 sprayability * 8th 8th 8th 8th 8th 8th 8th 8th 8th 8th 8th 8th wet river * (flow wet) 7 7 7 7 7 7 6 6 7 7 6 6 Evaporation time before base coat application [min] 5 30 15 15 10 Film thickness (μm) 30 30 27 22 35 34 30 41 34 35 30 41 basecoat Permahyd ^® Hi-Tec Primer 480 in RAL5010 (TDS version: EN / 480_0A.5) base coat film thickness 13 12 13 13 12 12 10 11 12 11 11 11 clearcoat Permasolid ^® HS Clearcoat 8055 / SH3225 / SH9034 (TDS version: EN / 8055A.10) Basecoat film thickness 44 42 43 42 49 49 44 42 48 48 45 45 Appearance after 24 hours (wavescan) DOI 96 94 96 96 89 90 89 88 88 89 92 88 Dullness 1 2 1 2 7 6 6 8th 8th 6 3 8th Tension (tension) 22 19 22 21 20 21 20 19 20 20 21 19 Shortwave 8th 16 6 6 25 22 27 28 26 26 19 28 Long Wave 3 6 3 3 4 4 5 5 4 4 4 6

The scratch hardness and smoothness of all applied filler films were tested 5, 10 and 15 minutes after application in a separate experiment on E-coated steel panels also at 22 ° C and 45% relative humidity. The results are shown in the following Table 6. The scratch hardness is a hardness test for the applied filler, which is performed by the operator with the fingernail. When smoothing, surface defects are carefully removed by hand with a soft and fine sanding pad. Mirka Abralon ^® 1000 polishing pads were used. Table 6: Development of the scratch hardness and the smoothing ability during the evaporation time of the applied filler Inventive examples market References Examples IE1.1 IE1.2 IE2.1 IE2.2 CE 3.1 CE 3.2 CE 3.3 CE 3.4 Film thickness (μm) 30 30 27 22 27 26 22 36 Scratch hardness * after 5 min 2 1 1 3 0 0 1 0 Scratch hardness * after 10 min 4 4 3 5 0 0 2 1 Scratch hardness * after 15 min 5 5 5 6 1 1 2 3 Smoothing * after 5 min 5 4 4 6 0 0 1 0 Smoothing * after 10 min 7 7 7 8th 0 0 6 5 Smoothing * after 15 min 9 9 9 9 2 3 7 7 * Ratings made by the client. Meaning of the ratings from 0 to 10: 0 = completely unacceptable 6 = Good 1 = very bad 7 = Good Excellent 2 = bad 8 = very well 3 = bad fair 9 = excellent 4 = fair 10 = Perfect 5 = pretty good, but not commercially acceptable

The compositions of IE 1 and IE 2 show the desired and superior combination of high end topcoat appearance and fast productivity. None of Examples 3.1-3.4 is as fast in the development of scratch hardness and early leveling ability as the compositions of IE1 and IE2. In addition, CE 3.1-3.4 does not achieve the high-end topcoat appearance when overcoated after 5 minutes of flashdown. The compositions of CE 3.1-3.4 do not even match the topcoat appearance of IE1 and IE2 when the flash-off times are extended to the flash-off times recommended in the respective technical data sheets.

Another advantage of the compositions of IE2.1 and IE2.2 is the long pot life as shown in Table 4 above. The low spray viscosities and the slow increase in viscosities over time ensure good sprayability, uniform flow of applied filler, and less structural integrity of the entire paint system, resulting in a superior topcoat appearance.

In addition, overlapping zones of applied surfacer layers of Examples IE1 and IE2 according to the invention look smooth, without edge imaging and do not show any disturbing spray dust which does not flow into already applied or subsequently applied surfacer layers (so-called overspray or underspray) and which remains visible after the topcoat.

Example 5: Moisture and Corrosion Protection Tests

Paint systems applied to E-coated steel panels obtained as described above were stored and tested for seven days at ambient temperatures. There were humidity tests after DIN EN ISO 6270 (240 h, 40 ° C, 100% humidity) and high pressure cleaning tests according to the Volkswagen standard PV1503 method B performed. A cross-hatch test was after DIN EN ISO 2409 (2 mm scratch distance, peel off with Tesafilm 4657). Table 7: Moisture test results of IE 1, IE 2 and CE 3 on E-coated steel plates Inventive example evaporated for 5 minutes Market example evaporated for 5 minutes Market reference to TDS evaporated example IE 1.1 IE 1.2 IE 2.1 IE 2.2 CE 3.1 CE 3.2 CE 3.3 CE 3.4 CE 3.1 CE 3.2 CE 3.3 CE 3.4 High pressure cleaning VW 0 0 0 0-1 3-4 *** 3 *** 2-3 *** 0-1 1-2 0-1 3 *** 0-1 PV1503B [mm] Crosshatch (initially) ** 0 0 0 0 0 0 0-1 0 0 0 2 *** 0 240h humidity test. Reviews after humidity test: Bubbles after 1h [Quantity / Size] * 0/0 0/0 0/0 0/0 0/0 0/0 0/0 0/0 0/0 0/0 0/0 0/0 blisters after 24h [quantity / size] * 0/0 0/0 0/0 0/0 0/0 0/0 0/0 0/0 0/0 0/0 0/0 0/0 Crosshatching after 1h ** 0 0 0 0 5 *** 0 0 0 0 0 0 0 Crosshatching after 24h ** 0 0-1 0 0 0 0 5 *** 0 0 0 5 *** 0 * Evaluation of the degree of bubble after DIN EN ISO 4628-2 : 0: no bubbles, 5: dense / big bubbles ** Evaluation of crosshatching after DIN EN ISO 2409 ; 2mm grid; Remove once with Tesa 4657 tape; Duplicate; Mean documented by two crosshatching. *** Separation between filler and basecoat

The compositions of IE1 and IE2 perform very well in high pressure clean and adhesion tests before and after exposure to moisture. Examples 3.1, 3.2 and 3.3 show weaknesses both in high-pressure cleaning and in adhesion tests, especially when the evaporation times are reduced to 5 minutes. Table 8: Moisture test results of IE 1 and IE 2 on pretreated steel plates prepared as described above Inventive examples example IE1.1 IE1.2 IE2.1 IE2.2 High pressure cleaning VW PV1503B [mm] 0 0 0 0-1 Crosshatch (initially) ** 1 1 0 0 240h humidity test. Reviews after humidity test: Bubbles after 1h [Quantity / Size] * 0/0 0/0 0/0 0/0 Blowing after 24h [Quantity / Size] * 0/0 0/0 0/0 0/0 Crosshatching after 1h ** 0 0 0 0 Crosshatching after 24h ** 0-1 1 0 0 * Evaluation of the degree of bubble according to DIN EN ISO 4628-2: 0: no bubbles, 5: dense / large bubbles ** Evaluation of crosshatching according to DIN EN ISO 2409; 2mm grid; Remove once with Tesa 4657 tape; Duplicate; Mean documented by two crosshatching.

Table 8 shows that the combined multilayer coating process on metal substrates as described above also results in very good adhesion behavior. The inventive method therefore combines a significantly reduced application time with very good quality results, even when metal substrates are coated.

Example 6: Application of the ready-to-use compositions of IE 1, IE 2 and CE 3 in combination with a solvent-based basecoat

The filler coating compositions of IE 1 IE 2 and CE 3 as described above were applied to another set of E-coated steel plates and ^® with a commercially available repair base coat solvent-based (Permacron basecoat 293/295/297 in 5010 chromaticity of Spies Hecker) and a repair clear coat solvent-based (Permacron ^® MS VarioPlus clearcoat 8050 / SH3310 overcoated activator / SH3364 thinner Spies Hecker) after 5 minutes flash-off at 22 ° C and a relative humidity of 45%. Basecoat and clearcoat compositions were applied according to their technical data sheets. After clearcoat application, the paint systems were baked at 60 ° C for 30 minutes. The appearance of the paint systems was measured 24 hours after clear baking and storage of the plates at ambient temperature with a Byk Gardner Wave-Scan Dual (catalog number 4840). Table 9: Results of wet-on-wet application process with solvent-based basecoat and solvent-based clearcoat on E-coated steel sheets: Inventive examples market References example IE1.1 IE1.2 IE2.1 IE2.2 CE CE CE CE 3.1 3.2 3.3 3.4 coatings 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 Evaporation time before base coat application 5 [Min] Film thickness (μm) 28 28 26 28 28 31 24 35 basecoat Permacron ^® base coat in RAL5010 (TDS version EN / 029XA.4) Basecoat film thickness 13 14 12 12 12 14 13 12 clearcoat Permacron ^® MS VarioPlus Clearcoat 8050 / SH3310 / SH3364 (TDS version EN / 8050A.8) Clearcoat film 65 65 65 65 58 58 55 55 Appearance after 24 hours (wavescan) DOI 86 86 86 87 87 87 89 84 Dullness 8th 8th 8th 8th 10 8th 6 12 Tension 20 19 20 20 19 19 18 17 Shortwave 32 31 30 30 28 30 24 35 Long Wave 5 6 4 4 5 5 8th 10

Application of the ready-to-use compositions of IE 1, IE 2 and CE 3 in combination with a solvent-based topcoat

The filler coating compositions of IE 1 IE 2 and CE 3 as described above were applied to another set of E-coated steel sheets and solvent-based with a commercially available repair topcoat (Permasolid ^® HS Automotive topcoat 275 in RAL 5010 Spies Hecker) after 5 minutes evaporation time at 22 ° C and a relative humidity of 45% according to his technical data sheet overcoated. After application of the topcoat, the paint systems were baked for 30 minutes at 60 ° C. The appearance of the paint systems was measured 24 hours after clear baking and storage of the plates at ambient temperature with a Byk Gardner Wave-Scan Dual (catalog number 4840). Table 10: Wet-on-wet application procedure with solvent-based topcoat on E-coated steel plates Inventive examples market References example IE1.1 IE1.2 IE2.1 IE2.2 CE CE CE CE 3.1 3.2 3.3 3.4 coatings 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 Evaporation time before base coat application [min] 5 Film thickness (μm) 28 28 26 28 28 31 24 35 topcoat Permasolid ^® HS Automotive Top Coat 275 in RAL 5010 (TDS version EN / 0275A.4) Topcoat film thickness 59 55 65 58 58 57 53 53 Appearance after 24 hours (wavescan) DOI 96 92 95 94 92 94 95 90 Dullness 1 4 2 3 5 2 2 7 Tension 24 22 24 24 23 24 23 20 Shortwave 8th 19 9 11 14 10 9 21 Long Wave 1 3 1 2 2 1 2 5

Table 9 and Table 10 show that the compositions of IE 1 and IE 2 have a similar or even better topcoat appearance when overcoated with a solventborne basecoat and clearcoat or a solventborne topcoat. However, the compositions of IE 1 and IE 2 additionally have better smoothness, as shown in Table 6 above.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• WO 2015/130502 Al [0034]
• WO 2014/106578 A1 [0069]
• DE 4415778 [0073]
• EP 05312249 [0073]
• EP 2862957 A1 [0084]
• EP 1571237 [0091]
• DE 10322446 [0091]
• WO 2015130502 A1 [0098]

Cited non-patent literature

• DIN EN ISO 2431 [0108]
• DIN 53211 [0108]
• DIN EN ISO 6270 [0119]
• DIN EN ISO 2409 [0119]
• DIN EN ISO 4628-2 [0119]

Claims (20)

A wet-on-wet method of multi-layer coating a substrate, the method comprising the steps of: (i) coating on the substrate to be coated a filler layer of an organic solvent-based surfacer coating composition comprising: A) at least one polyaspartic acid ester; B) at least one polyisocyanate crosslinking agent having free isocyanate groups; C) at least one pigment and / or filler; and D) at least one organic solvent; (ii) evaporating the surfacer layer; and (iii) applying a topcoat layer to the filler layer. Wet-in-wet process after Claim 1 wherein the surfacer coating composition further comprises E) at least one additional binder component. Wet-in-wet process after Claim 2 wherein the binder component is selected from the group consisting of hydroxy-functional binders, amino-functional binders, amino alcohol-functional binders, aldimines and / or ketimimes. Wet-in-wet process after Claim 1 wherein the surfacer coating composition B) comprises at least one aromatically bound polyisocyanate crosslinking agent having free isocyanate groups. Wet-in-wet process after Claim 1 wherein the evaporation of the filler layer is carried out for 15 minutes or less. Wet-in-wet process after Claim 1 wherein the topcoat layer comprises a basecoat layer and a clearcoat layer. Wet-in-wet process after Claim 1 wherein the topcoat layer is a pigmented one-step topcoat layer. Wet-in-wet process after Claim 6 wherein the clearcoat layer comprises at least one polyaspartic acid ester and at least one polyisocyanate crosslinking agent having free isocyanate groups. Wet-in-wet process after Claim 8 wherein the base coat layer comprises at least one polyisocyanate crosslinking agent having free isocyanate groups. Wet-in-wet process after Claim 6 , where the base coat is a water-based base coat. Wet-in-wet process after Claim 1 in which the polyaspartic acid ester is a compound of the formula (I):

wherein X represents an n-valent organic group obtained by removing the amino groups from a primary polyamine or polyetheramine; R ₁ and R _{2 are the} same or different organic groups which are inert towards isocyanate groups, R ₃ , R ₄ and R _{5 are} identical or different and represent hydrogen or organic groups which are inert toward isocyanate groups, and n represents an integer with a value of at least 2, or a chain-extended aspartate prepolymer which (i) is free of isocyanate groups, (ii) a reaction product of (ii-a) a mixture comprising at least one diaspartic ester and at least one amino-functional mono-aspartic acid ester, wherein the molar ratio between the at least one diaspartic ester and the at least one monoaspartic acid functional ester is about 99.5: 0.5 to about 50:50, and (ii-b) is at least one polyisocyanate. Wet-in-wet process after Claim 1 wherein the organic solvent based surfacer coating composition is applied using at least one manual pressure spray gun, a vacuum spray gun, airless and airmix techniques, pressure pot techniques, and non-manual automated techniques. Wet-in-wet process after Claim 1 wherein the substrate is a metal substrate. Wet-in-wet process after Claim 13 wherein the metal substrate comprises vehicle bodies or vehicle body panels. Wet-in-wet process after Claim 13 further comprising a step of pretreating the substrate to be coated with an acidic aqueous composition comprising at least one of phosphate ions, a water-soluble titanium compound and a water-soluble zirconium compound, and water. Wet-in-wet process after Claim 15 , further comprising a step of subjecting the pretreated substrate to an evaporation phase. Wet-in-wet process after Claim 15 wherein the acidic aqueous composition comprises about 1 to about 25 weight percent phosphate ion, based on the total amount of the acidic aqueous composition. Wet-in-wet process after Claim 15 wherein the acidic aqueous composition comprises about 0.3 to about 3% by weight, based on the total amount of the acidic aqueous composition, the water-soluble titanium compound and the water-soluble zirconium compound, calculated as elemental titanium and zirconium. Wet-in-wet process after Claim 15 wherein the water-soluble titanium compound and the water-soluble zirconium compound are selected from a group consisting of titanium-containing complex fluoro acids, zirconium-containing complex fluoro acids, fluoro complexes of titanium, fluorocomplexes of zirconium, and a combination thereof. Wet-in-wet process after Claim 15 wherein the acidic aqueous composition is applied by wiping.