DE19750451A1 - Preparation of multicoat paint for metal and plastic substrate - Google Patents

Abstract

Preparation of multicoat paint for metal and plastic substrates comprises applying a base paint on an optionally pretreated substrate, where the base paint is the sealing layer and comprises: (A) a physically dried, water dilutable, OH-free polyurethane(s) as an aqueous dispersion; (B) a water dilutable, OH-functional polyacrylate, polyester and/or polyurethane as an aqueous dispersion; (C) a polyisocyanate(s); and (D) fillers, pigments and/or other additives and aids. The ratio of NCO groups in (C):OH groups in (B) is 1:5-5:1.

Description

The invention relates to a method for multi-layer coating of metals and Plastic substrates, in particular plastic substrates with a structured surface. The process can be used in industrial, automotive and Vehicle parts painting, especially in vehicle refinishing.

In vehicle and industrial painting are increasing for ecological reasons environmentally friendly water or high-solid paints with a low proportion of volatile organic compounds used. This development is also in the Plastic coating. There are already a wide variety Water-based coating agent used.

When painting or refinishing surface-structured Plastic substrates, such as grained exterior parts of vehicles, such as e.g. B. bumpers, it is often desirable that the textured surface of the Plastic parts are preserved after painting. In such cases, one strives to of the paint to rebuild the surface structure of the plastic parts. Around So far, it has been customary to reproduce structured surfaces Coating agents, usually the fillers, structural additives such. B. Add polyamide powder of different particle size distribution. So in one Multi-layer painting for structured plastic surfaces, for example Filler coating agent applied with structural additives and a conventional one on the filler Basecoat applied. Another overpainting with a clear coat would, however due to the relatively high layer thicknesses, in which usually a clear coat applied, make the structuring effect ineffective again. For this For this reason, a clear coat has to be dispensed with. Because in this case the basecoat final coating of the multilayer structure, the basecoat must be next to it  color and / or effect function at the same time the function of the clear coat take.

Can be used with the known ones, for example, for plastic painting Waterborne basecoats can have clearcoat properties such as hardness, Scratch resistance, solvent and petrol resistance as well as water resistance are not be guaranteed. In addition, the gloss achieved is not with clear coats insufficiently overcoated waterborne basecoat. It is therefore necessary for this special If a modification of the water-based paints is used.

Furthermore, there is in the vehicle and vehicle refinishing during painting visible areas in the vehicle interior, e.g. B. door rebates, engine compartment, trunk, the Requirement to apply a clear coat for economic reasons dispense. Here, too, the above-mentioned special requirements for the Basecoat provided.

DE-A-195 29 395 describes a method for producing a Multi-layer painting on metallic substrates by electrophoretic application a primer, baking the primer layer and painting over with one Waterborne basecoat that contains hydroxyl-free binders and polyisocyanates. Of the Waterborne basecoat is baked at 130 ° C. No filler is used in this process applied and the clear coat can also be dispensed with. There are coatings with good gloss and stone chip resistance. Hardness, scratch resistance, solvent and Petrol resistance of these coatings as a final layer of one Multi-layer construction are still insufficiently developed, especially if the Multi-layer construction under the drying or curing conditions of the Car refinishing is created.

DE-A-196 06 022 describes a process for the production of aqueous Coating agents for painting vehicle interiors using a Mixing system described, wherein a premix is first prepared from a Pigments, water-dilutable hydroxy-functional binders and less than 5% by weight  Water-containing base paint (A) with a pigment-free aqueous component (B) preferably hydroxy-functional water-dilutable binders and one Polyisocyanate component (C). This premix is then used as a component (D) an aqueous solution of a rheological agent is added. Alternatively it is possible to prepare a premix from components (A), (B) and (D) and then add component (C). With these coating agents Get matt and scratch-resistant interior coatings without applying a clear coat have to. For vehicle exterior coating, for example of plastic parts, show the waterborne basecoat described here when applied without Clear varnish has insufficient resistance to solvents, petrol and water. In addition, it is desirable that the lacquered plastic add-on parts shine the rest of the painted body. Furthermore, it is in this one described process for the preparation of the coating compositions not easily possible, the preferably anhydrous component (A) with the other water-containing Mix components. The poor incorporability of component (A) leads to Defects in quality of the coating compositions produced in this way and / or those produced from them Coatings, e.g. B. to undesirable color deviations.

EP-A-0 751 197 describes aqueous binders which consist of a polyol and a polyisocyanate component, the polyol component being a mixture represents from a polyester and a hydroxyl and carboxyl groups physically drying polyurethane dispersion. The formulable from the binders Coating agents are used to coat or seal mineral Building material surfaces, such as plasters, surfaces containing gypsum, fiber cement building materials, Concrete, asphalt and bituminous road surfaces. They are particularly suitable Coating agent for painting wood, wood-based materials, furniture and parquet.

The object of the invention was to provide a process for the multi-layer coating of metallic and provide plastic substrates, which makes it possible to use environmentally friendly Paints to create a multi-layer structure that can be applied without the application of a clear coat high level of properties with regard to gloss, hardness, scratch resistance, solvent and Petrol resistance as well as water resistance shows, these properties also under  the conditions of car refinishing should be achieved. In addition, the coating agents used by simply mixing their components without any problems be producible. There should be color deviations in the applied coating materials be avoided.

The object is surprisingly achieved by the process forming an object of the invention for producing a multilayer coating on metallic and plastic substrates by applying a color and / or effect basecoat to a pretreated and / or precoated substrate, the basecoat forming the final layer of the multilayer structure, which is characterized in that an aqueous-based coating agent is applied as the color and / or effect-imparting basecoat comprising

• A) one or more physically drying water-dilutable essentially hydroxyl-free polyurethanes in the form of aqueous dispersions,
• B) one or more water-dilutable hydroxy-functional polyacrylates, polyester and / or polyurethanes in the form of aqueous dispersions,
• C) one or more polyisocyanates as well
  Water, color and / or effect pigments and, if appropriate, fillers, organic solvents and / or customary lacquer additives and auxiliaries,

the polyisocyanates being present in an amount such that the molar ratio the isocyanate groups in component C) to the hydroxyl groups in component B) 1: 5 to 5: 1, and wherein the aqueous coating agent is prepared by Mixing the water-containing components A) and B) with component C) and the other components of the coating agent.

Component A) and component B) are preferably in a weight ratio A): B) from 85:15 to 45:55, preferably from 80:20 to 50:50, particularly preferably  from 70: 30 to 55: 45 before, the weight fractions of components A) and B) refer to the resin solids and add 100.

It has been shown that with the method according to the invention Multi-layer painting can be created, even without the application of a clear coat a comparable one on the color and / or effect waterborne basecoat Property level achieved as it is achieved with a conventional basecoat / clearcoat structure becomes.

As component A) of that which can be applied in the process according to the invention Waterborne basecoats can be customary water-thinnable physically drying Polyurethane dispersions as are known in the art can be used. For example, there are water-thinnable polyurethane dispersions such as Formulation of waterborne basecoats used in vehicle refinishing become. Mixtures of various aqueous polyurethane dispersions are preferred used.

A particularly preferred mixture of polyurethane dispersions is a combination (I) of:

• a) 20-80% by weight, preferably 40-60% by weight, of one or more polyurethanes containing carbonate groups with a number average molecular weight (Mn) of 70,000 to 500,000, in the form of an aqueous dispersion, obtainable by reaction from
  • a1) 10-40% by weight of one or more organic polyisocyanates,
  • a2) 40-80% by weight of one or more higher molecular weight organic polyhydroxy compounds which consist of at least 50% by weight of one or more polyhydroxy polycarbonates,
  • a3) 0.2-18% by weight of one or more low molecular weight compounds which have at least two groups which are reactive toward isocyanate groups,
  • a4) 1-12% by weight of one or more compounds which, in addition to at least one anionic group or at least one group which can be converted into an anionic group, have at least one hydrogen atom which is reactive toward isocyanate groups, and
  • a5) 0-8% by weight of one or more nonionically hydrophilic compounds which have at least one isocyanate group or at least one group which is reactive toward isocyanate groups, the sum of components a1) to a5) being 100% by weight
  and
• b) 20-80 wt .-%, preferably 40-60 wt .-% of one or more carbonate-free and preferably urea-free, ionic groups-containing polyurethane resins with a number average molecular weight (Mn) of 10,000 to 300,000 and an acid number of 5 to 50 in the form of an aqueous dispersion, obtainable by preparing a polyurethane prepolymer containing OH groups with an OH number of 5 to 75 and a number average molecular weight (Mn) of 5,000 to 50,000, by reaction in an organic medium from
  • b1) one or more isocyanate-reactive compounds in the form of
  • b1.1) 70 to 100% by weight of one or more, preferably carboxyl-free, polyester polyols and / or polyether polyols with a number average molecular weight Mw of 400 to 6000, together with
  • b1.2) 0 to 30% by weight of one or more compounds different from b1.1) with at least two groups reactive with isocyanate, with a molecular weight of 60 to 400, the sum of components b1.1) and
  • b1.2) is 100% by weight with
  • b2) at least one compound with two isocyanate-reactive groups and at least one anionic group or one capable of forming anions, component b2) separately or in the form of a reaction product b2.1) from component b2) and one or more organic diisocyanates b2.2) can be used, the molar ratio of the groups of b2) reactive to isocyanate groups to the isocyanate groups of b2.2) being 1: 1.5 to 1: 2.5 and the reaction product b2.1) also in the presence of component b1 ) can be produced and component b2) or the reaction product b2.1) can be used in such an amount that the finished polyurethane resins have the desired acid number,
    as well as with
  • b3) one or more polyisocyanates with at least two free isocyanate groups per molecule, in such an amount that the molar ratio of the OH groups of component b1) to the NCO groups of components b2) and b3) is 1.01: 1 to 3 : 1 is
    whereupon the prepolymer obtained from b1), b2) and b3) is subjected to chain extension by reaction with before or after the partial or complete neutralization of groups which can be converted into ionic groups in the organic medium or after conversion into the water phase
  • b4) one or more polyfunctional isocyanates with a functionality of free NCO groups of at least 1.8, in proportions such that the finished polyurethane resins have the desired number average molecular weight,
  where the% by weight of components a) and b) each relate to the resin solids and add 100%.

The polyurethanes that can be used as component a) preferably have at least 200  Milliequivalents per 100 g solid in chemically incorporated carbonate groups -O-CO-O- on. They preferably contain no more than 320 milliequivalents per 100 g solid on chemically incorporated urethane groups -NH-CO-O and optionally chemically incorporated urea groups -NH-CO-NH-.

To produce the polyurethane dispersion a), component a1) is used in an amount 10-40% by weight, preferably 15-35% by weight, based on the solids content of a) used. Common aliphatic, cycloaliphatic can be used as component a1) and / or aromatic polyisocyanates with at least two isocyanate groups per molecule be used. The polyisocyanates preferably have a molecular weight of 112 to 1000, a molecular weight of 140-400 is particularly preferred. Examples of aliphatic and cycloaliphatic diisocyanates are isophorone diisocyanate, cyclopentylene diisocyanate, Hydrogenation products of aromatic diisocyanates, such as. B. cyclohexylene diisocyanate, Methylcyclohyxylene diisocyanate, dicyclohexylmethane diisocyanate, trimethylene diisocyanate, Tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, Propylene diisocyanate, ethyl ethylene diisocyanate, dimethyl ethylene diisocyanate.

Examples of aromatic diisocyanates which can be used are phenylene diisocyanate, Toluene diisocyanate, xylylene diisocyanate, biphenylene diisocyanate, naphthylene diisocyanate and diphenylmethane diisocyanate.

Component a1) can also contain a proportion of higher-quality polyisocyanates. As Triisocyanates are, for example, those products which are suitable by trimerization or Oligomerization of diisocyanates or by reaction of diisocyanates with polyfunctional compounds containing OH or NH groups are formed. Examples for this are the biuret of hexamethylene diisocyanate and water, the isocyanurate of Hexamethylene diisocyanate or the adduct of isophorone diisocyanate Trimethylolpropane.

Component a2) used to produce the polyurethane dispersion a) is shown in Amounts of 40-80 wt .-%, preferably 45-75 wt .-%, based on the Solids content of component a) used.  

Organic polyhydroxyl compounds with a number average molecular weight (Mn) of preferably 300-5000, particularly preferably of 500-3000 can be used. Component a2) contains at least 50% by weight, preferably to more than 70 wt .-% polyhydroxypolycarbonates of the above Molecular weight range. Polyhydroxypolycarbonates include esters of To understand carbonic acid, which by reaction of carbonic acid derivatives, for. B. Diphenyl carbonate or phosgene can be obtained with diols. As usable diols come z. B. ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,6-hexanediol, 1,8-octanediol, neopentyl glycol, 2-methyl-1,3-propanediol, 1,4-bishydroxymethylcyclohexane, 2,2,4-trimethyl-1,3-pentanediol, also diethylene glycol, Tri- and tetraethylene glycol, dipropylene glycol, polypropylene glycols, dibutylene glycol, Polybutylene glycols and bisphenol A in question.

The polyhydroxypolycarbonates should preferably be essentially linear. You can but also by installing polyfunctional components, in particular low molecular weight polyols, be slightly branched. Suitable low molecular weight polyols are e.g. B. glycerol, trimethylolpropane, 1,2,6-hexanetriol, 1,2,4-butanetriol, trimethylpropane, Pentaerythritol.

In addition to the polyhydroxy polycarbonates, component a2) can also be other from Polyurethane chemistry known per se polyhydroxyl compounds of the above Molecular weight range included. Examples of these are polyester diols Dicarboxylic acids, such as. B. from succinic acid, adipic acid, sebacic acid, and diols, e.g. B. from ethylene glycol, 1,2-propanediol, 1,3-propanediol, diethylene glycol, 1,4-butanediol, Hexanediol-1,6. Other examples of polyhydroxyl compounds are polylactone diols and Polyether diols.

Component a3) is used in amounts of 0.2-18% by weight, preferably 0.5-10% by weight, based on the solids content of a) used. For component a3) it is, for example, those known from polyurethane chemistry low molecular weight at least difunctional hydroxyl and / or amino groups  having compounds with molecular weights of, for example, 60-400. The Functional groups can have aliphatic, aromatic or alicyclic radicals be connected.

Examples of low molecular weight polyols are low molecular weight polyhydric alcohols with for example up to 20 carbon atoms in the molecule, such as ethylene glycol, diethylene glycol, Triethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol.

Examples of low molecular weight polyamines are alkylene polyamines with 1-30 C atoms, preferably with 2-12 C atoms. Linear or polyamines are preferred branched aliphatic, cycloaliphatic or aromatic structure and at least 2 primary amino groups. Diamines such as ethylenediamine, propylenediamine, 1,4-butylenediamine, piperazine, 1,4-cyclohexyldimethylamine, 1,6-hexamethylenediamine, Isophoronediamine, 4,4'-diamino-dicyclohexylmethane.

Component a4) is used in amounts of 1-12% by weight, preferably 1.5-6% by weight used. Component a4) is a compound with at least one one, preferably two, hydrogen atoms which are reactive toward isocyanate groups and at least one anionic or convertible group. Suitable groups which react with isocyanate are, in particular, hydroxyl groups and primary and / or secondary amino groups. Groups capable of forming anions are Carboxyl, sulfonic acid and / or phosphonic acid groups.

Preferred components a4) are dihydroxyalkanoic acids, such as. B. Dihydroxypropionic acid, dihydroxysuccinic acid, dihydoxybenzoic acid. Especially preferred are the alpha, alpha-dimethylolalkanoic acids, such as. B. 2,2-Di methylolacetic acid, 2,2-dimethylolpropionic acid, 2,2-dimethylolbutyric acid and 2,2-dimethylopentanoic acid. 2,2-Dimethylolpropionic acid is preferred.

To build up the polyurethane dispersion a), component a5) can optionally be used. Component a5) is preferred in amounts of 0-8% by weight 0.5-6 wt .-% used. Component a5) is, for example  having polyethylene oxide units built into polyether chains Compounds with at least one isocyanate group or at least one opposite Isocyanate reactive group.

The production of the polyurethanes a) containing carbonate groups from the Components a1) to a5) can be carried out in one or more stages in a manner known per se. The quantitative ratios of the reactants are chosen so that the Equivalent ratio of the isocyanate groups of component a1) and optionally that Component a5) to groups which are reactive toward isocyanate groups Components a2), a3), a4) and optionally a5) at 0.8: 1 to 2: 1, preferably 0.95: 1 to 1.5: 1. The total amount of ethylene oxide units and ionic Groups must be such that the dispersibility of the polyurethanes in water is guaranteed.

Examples of polyurethane dispersions which can be used in this way are described in detail in DE-A-39 36 794.

In the case of the polyurethane dispersion b), the preferably applicable combination (I) of Polyurethane dispersions are carbonate-free and preferred Polyurethanes free of urea groups.

Component b1) is used to produce the polyurethane dispersion b). At component b1), which is component b1.1) and optionally component b1.2) contains, it is preferably a polyol component with terminal OH groups. As component b1.1), polyether polyols such as. B. Poly (oxytetramethylene) glycols, poly (oxyethylene) glycols and poly (oxypropylene) glycols be used.

Furthermore, polyester polyols can be used as component b1.1). The Polyester polyols can, for example, in the usual way by esterification of organic dicarboxylic acids or their anhydrides with organic polyols become.  

Examples of organic polyols are diols such as alkylene glycols, for example Ethylene glycol, butylene glycol, neopentyl glycol and other glycols such as Dimethylolcyclohexane. In addition, small amounts of higher functional or Mixtures of higher and monofunctional OH components, such as. B. Trimethylolpropane. Pentaerythritol, glycerin, hexanetriol; Polyether, the condensates of Are glycols with alkylene oxides; Monoethers of such glycols, such as Diethylene glycol monoethyl ether and tripropylene glycol monomethyl ether used become.

Examples of organic dicarboxylic acids are phthalic acid, isophthalic acid, Terephthalic acid, tetrahydrophthalic acid, hexahydrophthalic acid, adipic acid, Azelaic acid, sebacic acid, fumaric acid, maleic acid, glutaric acid, succinic acid or Itaconic acid.

The polyester polyols which can be used as component b1.1) preferably have one Molecular weight from 400 to 6000, an OH number from 20 to 280 and an acid number from less than 3.

The optionally used low molecular weight compounds b1.2) it is, for example, low molecular weight alcohols. They are from the Polyurethane chemistry known per se in the sense of an isocyanate addition reaction compounds containing at least difunctional hydroxyl groups of less than 400 lying molecular weight.

Examples of components b1.2) are low molecular weight polyhydric alcohols such as Ethylene glycol, propanediol 1,2 and 1,3, butanediol 1,4 and 1,3, hexanediol 1,6, Octanediol-1,8, neopentyl glycol, 1,4-bishydroxymethylcyclohexane, 2-methyl-1,3-pro pandiol, 2,2,4-trimethylpentanediol-1,3, trimethylolethane, isomeric hexanetriols or Pentaerythritol or mixtures thereof.

To produce the polyurethane dispersion b), component b2) is used or a  Reaction product b2.1) from component b2) and component b2.2).

Suitable groups of component b2) which react with isocyanate groups are in particular hydroxyl groups and primary and secondary amino groups. For Groups capable of anion formation are e.g. B. carboxyl, phosphonic and Sulfonic acid groups. Compounds which can be used as component b2) and which have at least two groups reacting with isocyanates and at least one capable of forming anions Group included are e.g. B. Dihydroxy acids and diamino acids are suitable. Prefers are dihydroxyalkanoic acids, such as. B. dihydroxypropionic acid, dihydroxysuccinic acid, Dihydoxybenzoic acid. The alpha, alpha-dimethylolalkanoic acids are particularly preferred, such as B. 2,2-dimethylol acetic acid, 2,2-dimethylol propionic acid, 2,2-di methylolbutyric acid and 2,2-dimethylopentanoic acid. The is preferred 2,2-dimethylol propionic acid.

A preferred embodiment for the production of the polyurethane dispersion b) exists in that component b2) in the form of a reaction product b2.1) from component b2) and one or more diisocyanates b2.2) is used. As a reaction product b2.1) NCO-terminated compounds are formed. These are the connections essentially low molecular weight compounds.

The reaction products b2.1) can be added as a separate component. It is however, it is also possible to generate them from the mixture in situ, in the presence of b1) and continue to implement.

Any organic diisocyanates can be used as component b2.2), in particular with a molecular weight of less than 1200, for example 112 to 1000, or their mixtures are used. Examples of suitable diisocyanates are Trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, Hexamethylene diisocyanate, propylene diisocyanate, ethylene diisocyanate, 2,3-methylene ethylene diisocyanate, 1-methyltrimethylene diisocyanate, 1,3-cyclopentylene diisocyanate, 1,4-cyclohexylene diisocyanate, 1,2-cyclohexylene diisocyanate, 1,3-phenylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate,  1-isocyanatomethyl-5-isocyanato-1,3,3-trimethylcyclohexane, bis- (4-iso cyanatocyclohexyl) methane, bis (4-isocyanato-phenyl) methane, 4,4-diisocyanato diphenyl ether, 1,5-dibutylpentamethylene diisocyanate, tetramethylxylylene diisocyanate and 2,3-bis (8-isocyanato-octyl) -4-octyl-5-hexylcyclohexane.

Component b2) or reaction product b2.1) are used in such amounts that that the resulting polyurethane prepolymer has an acid number of 5-50 mg KOH / g has, preferably between 15-40 mg KOH / g.

Any component can be used as component b3) to produce the polyurethane dispersion b) organic polyisocyanates, optionally also as a mixture, are used. It can are, for example, the diisocyanates mentioned under b2.2).

Component b4) includes, for example, the known polyisocyanates known in lacquer suitable, as they were also mentioned above for component b2.2).

The amounts of components b1) to b4) are chosen so that a during the reaction Reaction product with terminal OH groups is formed, d. H. it will be with one Worked polyol excess. One can with an OH to NCO ratio of 1.01 to Work 3: 1, preferably the range is 1.05 to 2: 1, particularly preferably from 1.1 to 1.5: 1. The reaction products preferably have a number average molecular weight (Mn) of 5000-50,000, more preferably over 8,000 and under 30,000, and a preferred one OH number of 5-75 mg KOH / g, particularly preferably above 10 and below 50 mg KOH / g. The reaction can take place in a mixture of all components or the reaction takes place gradually.

Examples of polyurethane dispersions b) are described in detail in the EP-A-0 634 431.

Examples of preferred combinations (I) of the polyurethane dispersions a) and b) are described in the as yet unpublished German patent application P 196 43 802.0.  

A further preferred combination (II) of water-dilutable polyurethane dispersions contains

• c) 45-95% by weight of one or more polyurethanes, in particular with one number average molecular weight Mn of 10,000 to 500,000, produced by radical initiated polymerization of polyurethane macromonomers containing Carboxyl, phosphonic or sulfonic acid groups and lateral vinyl groups as well optionally terminal vinyl, hydroxy, urethane, thiourethane and / or Urea groups in a solvent serving with the Polyurethane macromonomer copolymerizable unsaturated monomers, optionally in the presence of further copolymerizable unsaturated Monomers, in the form of an aqueous dispersion and
• d) 5-55% by weight of the ionic groups free of urea groups mentioned under b) containing polyurethane resins with a number average molecular weight (Mn) of 10,000 to 300,000 and an acid number of 5 to 50 in the form of an aqueous Dispersion.

The polyurethane dispersion c) is one or more polyurethanes, produced by radical-initiated polymerization of polyurethane macromonomers Containing carboxyl, phosphonic or sulfonic acid groups and lateral Vinyl groups and optionally terminal vinyl groups, hydroxyl, urethane, Thiourethane and / or urea groups in a serving as a solvent, with the Polyurethane macromonomer copolymerizable unsaturated monomers, if necessary in the presence of further copolymerizable unsaturated monomers or by free radicals initiated polymerization of the polyurethane macromonomers in a mixture of water and an organic solvent inert to isocyanate groups, in the presence of unsaturated copolymerizable with the polyurethane macromonomers Monomers, and optionally distilling off the organic solvent before or after radical polymerization. The polyurethanes are in the form of aqueous dispersions in front.  

The polyurethane dispersions c) can be prepared in various ways. A Weg is, for example, that a polyurethane macromonomer is made by polyaddition of polyhydroxy compounds from the group of polyhydroxy polyethers, Polyhydroxy polyesters or polyhydroxy polycarbonates, further Polyhydroxycarboxylic acids, dihydroxyphosphonic acids and / or polyhydroxysulfonic acids, and polyisocyanates and one or more at least two hydroxy and monomers containing at least one vinyl group. The proportions of the Reactants, especially polyisocyanate, are chosen so that the Macromonomer no longer contains hydroxy groups. The macromonomer that Carboxyl, phosphonic acid and / or sulfonic acid groups and lateral vinyl groups contains, after neutralization and transfer into an aqueous dispersion over the Vinyl groups with copolymerizable unsaturated monomers and radical-forming Initiators polymerized.

A second way is that in contrast to the previously described variant the ratio of polyisocyanate is chosen so that a macromonomer with terminal isocyanate groups. This macromonomer also contains Carboxyl, phosphonic acid or sulfonic acid groups as well as lateral vinyl groups. The free isocyanate groups of this macromonomer are then with primary or secondary amines or thioalcohols with formation of urea, urethane or Thiourethan groups implemented. The macromonomer modified in this way then also becomes about the vinyl groups with copolymerizable unsaturated monomers and Free radical initiators polymerized.

A third way is that, as described above, a polyaddition product is produced and an excess of polyisocyanate is also used here, so that the resulting macromonomer lateral vinyl groups, carboxyl, phosphonic acid or Has sulfonic acid groups and terminal isocyanate groups. This macromonomer is then reacted with a monomer which in addition to a vinyl group Contains group that reacts with isocyanate groups, such as the hydroxyl, amino or Mercapto group. These monomers can be used alone, but it is also  possible to mix these monomers with primary or secondary amines, To use alcohols or thioalcohols. This way you get one Macromonomer containing lateral vinyl groups as well as terminal vinyl groups. This Macromonomer is then also in the last stage with the vinyl groups copolymerizable unsaturated monomers and free radical initiators polymerized.

Examples of polyhydroxy compounds for the production of Polyurethane macromonomers that can be used are polyhydroxy polyethers Poly (oxytetramethylene) glycols, poly (oxyethylene) glycols and poly (oxypropylene) glycols. The preferred polyhydroxy polyethers are poly (oxypropylene) glycols with a Molecular weight in the range of 400 to 5000.

Examples of usable polyhydroxy polyesters are those made by Esterification of organic polycarboxylic acids or their anhydrides with organic ones Polyols. The polycarboxylic acids and the polyols can be aliphatic or aromatic Be polycarboxylic acids and polyols.

Close the polyols that can be used to make the polyhydroxy polyesters Alkylene glycols such as ethylene glycol, butylene glycol, neopentyl glycol and other glycols such as diethylolocyclohexane and trishydroxyalkylalkanes, such as. B. trimethylolpropane and Tetrakishydroxyalkylalkane, such as. B. pentaerythritol, a.

The acid component of the polyhydroxy polyester consists primarily of low molecular weight polycarboxylic acids or their anhydrides with 2 to 18 Carbon atoms in the molecule. Suitable acids are, for example, phthalic acid, Isophthalic acid, terephthalic acid, tetrahydrophthalic acid, hexahydrophthalic acid, Succinic acid, adipic acid, azelaic acid, sebacic acid, maleic acid, glutaric acid, Hexachloroneptanedicarboxylic acid, tetrachlorophthalic acid, trimellitic acid and pyromellitic acid.

Examples of polycarbonate polyols that can be used are those of the number average Molecular weight range (Mn) from 300 to 5000, preferably 500 to 3000.  

These OH-functional polycarbonates can be, for example, by reacting Polyols such as 1,3-propanediol, 1,6-butanediol, diethylene glycol, triethylene glycol, 1,4-bishydroxymethylcyclohexane, 2,2-bis (4-hydroxycyclohexyl) propane, neopentyl glycol, Trimethylolpropane, pentaerythritol, with dicarbonates such as dimethyl, diethyl or Diphenyl carbonate, or with phosgene. Mixtures of such polyols can can also be used.

It is of particular importance for the polyurethane dispersions that the Macromonomers that lead to these dispersions, lateral vinyl groups as well optionally also contain terminal vinyl groups. The term terminal Vinyl groups shall denote those vinyl groups which are at the beginning or end of the Polymer chain hang, lateral vinyl groups are those that are not in the beginning or end of the polymer chain, but are installed in between.

The lateral vinyl groups in the polyurethane dispersions are obtained by incorporation of such monomers in the macromonomer that have at least two hydroxyl groups and identify at least one vinyl group. Examples include trimethylol propane (TMP) derivatives such as e.g. B. TMP monoallyl ether (2-propenyloxy-2-hy droxymethylpropanol), TMP mono (meth) acrylate (2- (meth) acryloyloxy-2-hy droxymethylpropanol); Glycerol mono (meth) acrylate; Adducts of alpha, beta-un saturated carboxylic acids, such as (meth) acrylic acid, on diepoxides, e.g. B. Bisphenol-A-di glycidyl ether, hexanediol diglycidyl ether; Adducts of dicarboxylic acids, such as. B. Adipic acid, terephthalic acid or the like on (meth) acrylic acid glycidyl ester; Monovinyl ethers of polyols.

The preparation of the polyurethane macromonomers can be carried out according to the usual and Known urethane chemistry methods. The reaction takes place in particular in Presence of a solvent or in the presence of so-called reactive thinners instead. The reactive diluents are alpha, beta-unsaturated monomers, which in the final stage copolymerized with the macromonomers containing vinyl groups become. Examples of such reactive diluents are alpha, beta-unsaturated  Vinyl monomers such as alkyl acrylates, methacrylates and crotonates with 1 to 20 Carbon atoms in the alkyl radical, di-, tri- and tetracrylates, methacrylates, crotonates from Glycols, tri- and tetrafunctional alcohols, substituted and unsubstituted acrylic and Methacrylamides, vinyl ethers, alpha, beta-unsaturated aldehydes and ketones, Vinyl alkyl ketones with 1 to 20 carbon atoms in the alkyl radical, vinyl ethers, vinyl esters, Diesters of alpha, beta-unsaturated dicarboxylic acids, styrene, styrene derivatives, such as. B. alpha-methyl styrene.

The macromonomers thus obtained are then neutralized if the acidic groups in the monomers which carry such groups, not in advance neutralized form were used.

To prepare the polyurethane dispersions c), those containing vinyl groups are used Macromonomers converted into an aqueous dispersion by adding water and by methods known per se by radical-initiated polymerization polymerized. In this polymerization, if not from the outset as so-called Reactive diluent present, monomers of this type, as described above, added, which are then polymerized into the polyurethane.

The polyurethanes thus obtained have a number average molecular weight (Mn) of 10,000 to 600,000, preferably 30,000 to 500,000, particularly preferably 50,000 to 250,000. The proportion of unsaturated polymerized into the polyurethane macromonomer Monomers is preferably greater than or equal to 5% by weight, particularly preferably 15% by weight or more, based on the weight of the finished total resin. The Acid numbers of the polyurethane dispersions are in the range from 5 to 80 mg KOH / g, preferably at 10 to 40 mg KOH / g.

Such polyurethane dispersions and their preparation are described in the DE-A-41 22 265.

Examples of preferred combinations (II) of polyurethane dispersions from the Polyurethane dispersions c) and d) are described in DE-A-43 44 063.  

As component B) of the waterborne basecoat applied in the process according to the invention are common hydroxy-functional water-dilutable binder dispersions in paints based on polyurethane, polyacrylate and / or polyester resin. It can for example the hydroxyfunctional known from the prior art Polyurethane, polyacrylate and polyester resins act as they formulate aqueous two-component polyurethane paints are used.

The hydroxy-functional polyurethane, polyacrylate and polyester resins are are, for example, those with an OH number of 25-250 mg KOH / g and a Number average molecular weight (Mn) of 1000-500 000.

Hydroxy-functional polyurethane resins are preferably used as component B). It is particularly preferred to use anionically modified polyurethane resins which can optionally be modified with fatty acids.

The particularly preferred anionically modified hydroxy-functional polyurethane resins have, for example, an OH number of 25-250 mg KOH / g, preferably 40-140 mg KOH / g, a urethane group content of 2-20% by weight, preferably 5-15% by weight, based on the resin solids, a number average molecular weight (Mn) of 1000 to 100,000, preferably from 1,500 to 50,000 and an acid number of preferably 10-35 mg KOH / g, particularly preferably from 15-25 mg KOH / g. The polyurethane resins can additionally be nonionically modified. For example, you can have a salary Ethylene oxide units of less than 200 mEqu, preferably less than 150 mEqu, particularly preferably have less than 100 mEqu.

Anionically or anionically and nonionically modified hydroxy-functional polyurethane resins, which are obtainable by, are particularly preferably used as component B)

• 1) Preparation of a precursor containing NCO groups
  • 1a) at least one compound with two isocyanate-reactive groups and at least one anionic or anion-forming group,
  and / or one or more compounds having at least one pendant, hydrophilic chain with ethylene oxide units and two groups which are reactive with isocyanate, and from
  • 1b) one or more aliphatic or cycloaliphatic diisocyanates, optionally together with one or more aliphatic or cycloaliphatic diisocyanates with at least one pendant hydrophilic chain with ethylene oxide units,
• 2) Production of a polyester containing OH groups
  • 2c) one or more polyalcohols,
  • 2d) one or more dicarboxylic acids,
  • 2e) optionally one or more fatty acids and
  • 2f) optionally one or more polyols with at least one pendant hydrophilic chain with ethylene oxide units, and
• 3) subsequent reaction of the products obtained under 1) and 2), if appropriate in the presence of one or more monoisocyanates with a hydrophilic chain with ethylene oxide units, in such quantities that the OH groups of under 2) precondensates obtained in excess over the existing ones NCO groups are present.

As component 1a) for the preparation of the precursor product containing NCO groups for example, the compounds described as component b2) are suitable. 2,2-Dimethylolpropionic acid is also preferred here.

Component 1b) includes, for example, those described as component b2.2)  Diisocyanates in question.

For the preparation of the NCO-containing preadduct, a molar ratio of the with isocyanate groups reactive from 1a) to the isocyanate groups of 1b) from 1: 1.5 to 1: 2.5 observed.

To produce the polyester containing OH groups, component 2c) Usual polyalcohols known for the production of polyesters can be used. Examples of such polyalcohols are glycols such as ethylene glycol, 1,2-propanediol and 1,3, 1,2-butanediol, 1,3 and 1,4, 2-1,3-propanediol, neopentyl glycol, 2,2-trimethylpentanediol-1,2, hexanediol-1,6, cyclohexanediol-1,2 and -1,4, 1,2- and 1,4-bis (hydroxymethyl) cyclohexane, adipic acid bis (ethylene glycol ester), ether alcohols such as di- and Triethylene glycol, dipropylene glycol, dimethylolpropionic acid, oxalkylated bisphenols with two C2-C3-oxalkyl groups per molecule, perhydrogenated bisphenols, 1,2-butanetriol, Hexanetriol-1,2,6, trimethylolethane, trimethylolpropane, trimethylolhexane, glycerin, Pentaerythritol, dipentaerythritol, sorbitol.

Proportionate chain-terminating monohydric alcohols, for example, can also be used those with 1-8 C atoms in the molecule, such as propanol, butanol, cyclohexanol, n-hexanol, Benzyl alcohol, hydroxypivalic acid can be used.

To produce the polyesters containing OH groups, component 2d) for example polycarboxylic acids customary for polyester production or their derivatives capable of esterification. It can be aliphatic, act cycloaliphatic and / or aromatic dicarboxylic acids with 4-36 atoms, which can be linear or branched. It is preferably Dicarboxylic acids with 4-12 carbon atoms per molecule. Examples of suitable ones Dicarboxylic acids and their derivatives are phthalic anhydride, isophthalic acid, Terephthalic acid, dimethyl terephthalate, tetrahydro- and Hexahydrophthalic anhydride, cyclohexanedicarboxylic acid, alkyl succinic anhydride, Succinic acid, glutaric acid, sebacic acid, azelaic acid, adipic acid, Norbonenedicarboxylic acid, pyromellitic anhydride, fumaric acid, maleic acid and their  Anhydrides.

For the preparation of the polyester containing OH groups, component 2e) is preferred used so that a fatty acid-modified polyester is formed. As component 2e) come for example aliphatic or aromatic monocarboxylic acids with 6-35 C-Ato men in question. The monocarboxylic acids can be saturated or unsaturated. Examples suitable saturated monocarboxylic acids are 2-ethylhexanoic acid, isononanoic acid, Versatic acid, neodecanoic acid, dodecanoic acid, stearic acid, palmitic acid, Coconut oil fatty acid or hydrogenated technical fatty acids or fatty acid mixtures. Examples for unsaturated monocarboxylic acids of the corresponding chain length are soybean oil fatty acid, Castor oil fatty acid, sorbic acid, peanut oil fatty acid, tall oil fatty acid and ricinin fatty acid. Saturated aliphatic fatty acids are preferably used.

Component 2f) can be used to prepare the polyester containing OH groups if non-ionic hydrophilic groups in the form of ethylene oxide groups in the Polyester should be imported.

The production of the hydroxy functional polyurethane resins from the NCO groups containing pre-duct and the OH group-containing polyester for example by reaction in the melt or in anhydrous organic Solvents that do not react with isocyanate groups, for example at temperatures from 60-160 ° C.

The proportions of the reactants are selected so that the Equivalent ratio of OH groups to NCO groups is greater than 1 and the desired hydroxyl number is achieved. Then the transfer takes place Reaction product in the aqueous phase with the addition of water and optionally Distill off existing solvents. To achieve sufficient The ion-forming groups of the polyurethane resin, preferably the anionic groups are neutralized. The neutralization can be done before or during the transfer into the water phase. Making the aqueous Polyurethane dispersion is carried out by methods known to those skilled in the art.  

The preferred anionically and optionally non-ionically modified Hydroxy-functional polyurethane resins and their manufacture are detailed described in WO-A-94/03511 and WO-A-94/03512.

It is also possible to use silicon-modified as hydroxy-functional polyurethanes hydroxy-functional polyurethanes, as described in the as yet unpublished German Patent application P 196 24 972 are described to use.

The hydroxy-functional polyurethane resins can optionally be mixed with other film-forming hydroxy-functional polymers known to the person skilled in the art be used.

Component C) of the waterborne basecoats to be used according to the invention is concerned any organic polyisocyanates with aliphatic, customary in the paint sector, cycloaliphatic, araliphatic and / or aromatically bound free isocyanate groups. They are liquid at room temperature or liquefied by the addition of organic solvents. The polyisocyanates generally have a viscosity of 1 to 6000 mPas at 23 ° C. preferably above 5 and below 3000 mPas.

The polyisocyanates are preferably polyisocyanates or Polyisocyanate mixtures with only aliphatic and / or cycloaliphatic bound isocyanate groups with an average NCO functionality of 1.5 to 5, preferably 2 to 3.

For example, "paint polyisocyanates" based on hexame are particularly suitable ethylene diisocyanate, 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethyl-cyclohexane (IPDI) and / or bis (isocyanatocyclohexyl) methane and the known biuret, Derivatives of allophanate, urethane and / or isocyanurate groups Diisocyanates, preferably in a known manner following their preparation by distillation of excess starting diisocyanate to a residual content of less than 0.5% by weight have been exempted.  

So-called sterically hindered polyisocyanates, such as e.g. B. 1,1,6,6-tetramethyl-hexamethylene diisocyanate, 1,5-dibutyl-penta-methyl diisocyanate, p- or m-tetramethylxylylene diisocyanate and the corresponding hydrogenated homologues. These diisocyanates can also be functionalized in a suitable manner Connections are implemented, for example by trimerization or by Reaction with water or trimethylol propane.

Aromatic polyisocyanates are also suitable, but less preferred. Examples for this are polyisocyanates based on 2,4-diisocyanatotoluene or mixtures thereof with 2,6-diisocyanatoluene or based on 4,4'-diisocyanatodiphenylmethane and their Trimer.

The use of specially hydrophilized polyisocyanates is also favorable. Such Hydrophilized polyisocyanates are e.g. B. by implementing di- or Polyisocyanates with monofunctional polyethers made from ethylene oxide and optionally Propylene oxide and / or by incorporating carboxylate groups by reaction with Obtained hydroxyl-containing carboxylic acids. This modification will the emulsification of the polyisocyanate in the aqueous phase facilitated.

The polyisocyanate crosslinkers are known to the person skilled in the paint industry.

Waterborne basecoats which can be applied in the process according to the invention contain color and / or effect pigments. Color pigments are all common pigments suitable organic or inorganic nature. Examples of inorganic or organic color pigments are titanium dioxide, micronized titanium dioxide, iron oxide pigments, Carbon black, azo pigments, phthalocyanine pigments, quinacridone or pyrrolopyrrole pigments. The effect pigments are particularly characterized by a platelet-like Construction from. Examples of effect pigments are: metal pigments, e.g. B. made of aluminum, Copper or other metals; Interference pigments, such as e.g. B. metal oxide coated Metal pigments, e.g. B. titanium dioxide coated or mixed oxide coated aluminum, coated mica, e.g. B. titanium dioxide coated mica and  Graphite effect pigments.

Coating agents which can be used as water-based paints in the process of the invention can Contain customary fillers as well as additives and auxiliaries customary in paint.

Examples of fillers are barium sulfate, talc, silicon dioxide.

Examples of customary paint additives are rheology-influencing agents, such as highly disperse ones Silicic acid, layered silicates or polymeric urea compounds. Act as a thickener also, for example, with water-soluble cellulose ethers and synthetic polymers ionic and / or associative groups such as modified ethoxylated Polyurethanes or polyacrylates and polypeptides. Other examples are anti-sedatives, Leveling agents, light stabilizers, anti-foaming agents, such as silicone-containing Links; Wetting agents and adhesion-promoting substances are used. The Additives and auxiliaries are used in the usual amounts familiar to the skilled worker, depending on the desired effect, added.

Coating agents which can be used as water-based paints in the process of the invention can small amounts of organic solvents, preferably not more than 15% by weight, especially preferably contain no more than 10% by weight. The organic solvents are preferably water miscible. These are common paint solvents. This can originate from the production of the binders or are added separately. Examples of such solvents are monohydric or polyhydric alcohols, e.g. B. propanol, Butanol, hexanol; Glycol ether or ester, e.g. B. diethylene glycol dialkyl ether, Dipropylene glycol dialkyl ether, each with C1 to C6 alkyl, ethoxypropanol, butyl glycol; Glycols, e.g. B. ethylene glycol, propylene glycol and their oligomers, N-methylpyrrolidone as well as ketones, e.g. B. methyl ethyl ketone, acetone, cyclohexanone; aromatic or aliphatic hydrocarbons, e.g. B. toluene, xylene or linear or branched C6-C12 aliphatic hydrocarbons. About the choice of solvents can The course and viscosity of the coating agent are influenced.

The waterborne basecoats can be used to neutralize the ionically modified binders  Contain neutralizing agents. As a neutralizing agent for the preferred anionic modified binders serve bases such. B. ammonia or organic amines such as Triethylamine, N-methylmorpholine, amino alcohols such as dimethylisopropanolamine, Dimethylethanolamine, 2-amino-2-methylpropanol-1.

The waterborne basecoats which can be used in the process according to the invention are obtained by Mixing the water-containing components A) and B) with component C) and the other components. Mixing is easy without any help larger mixing units, e.g. B. by simply stirring with a stir bar, possible. Mixing can be done in different orders. For example, from the physically drying polyurethane dispersion (component A) or from the OH-functional polyurethane dispersion (component B) a formulation can be prepared which contains the pigments and the necessary additives, solvents and auxiliary substances. Then component B) or component A) and component C), optionally completed with solvents and / or paint additives, separately be added. However, it is also possible to use components A) and B) Prepare formulation containing the pigments and the necessary additives, solvents and contains auxiliary substances. Then component C), optionally with Provide solvents and / or additives, mixed. Component A) and / or Component B) can be formulated with the appropriate pigments and additives are also available as components of a mixing system to achieve defined colors. There it is the water-based paints a two-component system required that components A) and B) stored separately from component C) and are only mixed thoroughly shortly before application. Then can with water or small amounts of organic solvents if necessary Spray viscosity can be set.

To produce the waterborne basecoats to be used, it is also possible to use the Color pigments first rub in a paste resin and then how to be incorporated into component A) and / or component B) as described above. At the paste resins can, for example, be conventional paste resins based on water-dilutable polyester, polyacrylate and / or polyurethane resin dispersions  act. Polyurethane paste resins to be used with preference are described, for example in EP-A-0 438 090.

In the process according to the invention for producing a multi-layer coating, the Color and effect waterborne basecoat applied to a pre-coated substrate. The pre-coated substrates are metallic or Plastic substrates. Metallic substrates are, for example, those used in vehicle construction usually used metal substrates. Plastic substrates are, for example common plastics used in vehicle construction, such as polypropylene, Ethylene propylene diene copolymers (EPDM), polycarbonates, glass fiber reinforced Plastics, polyurethanes, polyamides, thermoplastic polyesters and Acrylonitrile / butadiene / styrene copolymers (ABS).

The waterborne basecoat can be applied to differently pre-coated metallic and Plastic substrates are applied. The substrates can be usual applied in the vehicle series and vehicle refinishing Trade substrates. It can be particularly the case with vehicle refinishing depending on the condition of the damaged area to be repaired, for example by one sanded old paintwork or already in the context of refinishing applied coating layers. In the context of the refinishing applied coating layers can be, for example, those of the person skilled in the art known adhesive primers, primers, primer filler or filler layers. The Coating agents can be solvent-based or water-based.

Different multi-layer structures are possible. For example, it can be a three-layer structure act from a primer, e.g. B. based on chlorinated Polyolefins (CPO) as the main binder, a filler, e.g. B. a 2K epoxy or 2-component acrylic filler and the water-based paint. It can also be a two-layer construction act, for example from a commercially available primer filler, e.g. B. based 2K acrylic, and the water-based paint. However, it is also possible to apply the waterborne basecoat directly to be applied to a sanded old paintwork.  

The drying or curing conditions under which the multi-layer coating is created, correspond to e.g. B. in the car series and car refinishing usual conditions. For example, the waterborne basecoat can be applied to a previously applied one Filler or primer filler layer after a flash-off phase, e.g. B. 15-30 minutes for example at room temperature, applied and then z. B. 40-60 minutes at z. B. 40-60 ° C can be cured.

The coating agents are applied by known methods, preferably by spray application upset.

The invention also relates to the use of the water-dilutable coating compositions the binder composition from components A), B) described above and C) as color and / or effect basecoats in processes for producing a Multi-layer painting on metallic and plastic substrates, with the basecoat on precoated substrates is applied and the last final lacquer layer in the Multilayer construction forms.

With the method according to the invention, in particular in applications in which for technological or economic reasons on the application of a clear coat must or should be dispensed with, multi-layer coatings, the usual Requirements in vehicle and especially in vehicle refinishing correspond. The coatings show a good gloss, good gasoline, solvent and Water resistance as well as sufficient hardness and scratch resistance. Particularly advantageous is that with the method according to the invention the desired level of properties Painting also under the drying or curing conditions of the Car refinishing is achieved. The applied in the method according to the invention Waterborne basecoats can be easily mixed by simply mixing them together Manufacture components.

The invention is illustrated by the following examples.

All information is based on weight, unless otherwise stated.  

example 1 Production of a water-based paint

A plain-colored water-based paint is produced.

A combination of a polyurethane dispersion A1 is used as component A) (corresponds to the polyurethane dispersion A from preparation example 1 of DE-A-43 44 063) and a polyurethane dispersion A2 (corresponds to polyurethane dispersion B from Production example 2 of DE-A-43 44 063) used.

An OH-functional polyurethane dispersion is used as component B) WO-A-94/03511 Example 4, synthetic resin binder 4 used.

A commercially available polyisocyanate hardener based on water-dilutable aliphatic polyisocyanates (Bayhydur® LS-2032) is used as component C).

• 1.1. A formulation with the following constituents is first prepared from the physically drying polyurethane dispersions A1 and A2 mentioned above:
  7.0 parts of polyurethane dispersion A1
  18.4 parts polyurethane dispersion A2
  28.5 parts of water
  3.7 parts butyl glycol
  1.28 parts of a commercially available thickener
  0.2 parts of N, N-dimethylethanolamine
  18.6 parts of a commercially available titanium dioxide pigment
  0.4 parts of a commercially available copper phthalocyanine pigment
  0.12 parts of a commercially available defoamer
  10.0 parts of a commercially available PU grinder (FK 30%).
• 1.2. To 100 parts by volume of the under 1.1. The following components are added one after the other and the individual ingredients are thoroughly stirred:
  • - 30 parts by volume of a preparation from:
  • 76% by weight of the OH-functional polyurethane dispersion (component B)
  • - 12.5% by weight of fully demineralized water (deionized water)
  • - 3.0% by weight of butyl glycol
  • - 3.5 wt .-% of a commercially available silica matting
  • - 5 wt .-% of a commercially available thickener based on acrylate
  • - 30 parts by volume of the polyisocyanate hardener (component C) 75% in methoxypropylacetate
  • - 30 parts by volume of demineralized water.

Example 2 Production of a multi-layer paint

The following multi-layer coating was carried out using the waterborne basecoat produced in Example 1:
A polypropylene substrate was cleaned in the usual way. Then a customary solvent-based 2-component filler based on a hydroxy-functional acrylic resin and a polyisocyanate hardener was applied. After a flash-off time of 30 minutes at room temperature, the waterborne basecoat was applied. The mixture was then cured at 60 ° C. for 60 minutes.

The paint obtained in this way meets the usual requirements for a Car refinishing in terms of hardness, scratch resistance, solvent and Petrol resistance and water resistance.

Claims (9)

1. A process for producing a multi-layer coating on metallic and plastic substrates by applying a color and / or effect basecoat to an optionally pretreated and / or pre-coated substrate, the basecoat forming the final layer of the multi-layer structure, which is characterized in that and / or effect-imparting basecoat is applied containing an aqueous-based coating composition

• A) one or more physically drying water-dilutable, essentially hydroxyl-free polyurethanes in the form of aqueous dispersions,
• B) one or more water-dilutable hydroxy-functional polyacrylates, polyesters and / or polyurethanes in the form of aqueous dispersions,
• C) one or more polyisocyanates as well
  Water, color and / or effect pigments and, if appropriate, fillers, organic solvents and / or customary lacquer additives and auxiliaries,

the polyisocyanates being present in such an amount that the molar ratio of the isocyanate groups in component C) to the hydroxyl groups in component B) is 1: 5 to 5: 1. 2. The method according to claim 1, characterized in that in the basecoat Component A) and component B) in a weight ratio of 85:15 to 45: 55, the weight fractions of components A) and B)  refer to the resin solids and add 100. 3. The method according to claim 1 or 2, characterized in that as a component A) the basecoat mixtures of various aqueous polyurethane dispersions be used. 4. The method according to claim 3, characterized in that the mixture of polyurethane dispersions is a combination of:

• a) 20-80% by weight of one or more polyurethanes containing carbonate groups with a number average molecular weight (Mn) of 70,000 to 500,000, in the form of an aqueous dispersion, obtainable by reacting
  • a1) 10-40% by weight of one or more organic polyisocyanates,
  • a2) 40-80% by weight of one or more higher molecular weight organic polyhydroxy compounds which consist of at least 50% by weight of one or more polyhydroxy polycarbonates,
  • a3) 0.2-18% by weight of one or more low molecular weight compounds which have at least two groups which are reactive toward isocyanate groups,
  • a4) 1-12% by weight of one or more compounds which, in addition to at least one anionic group or at least one group which can be converted into an anionic group, have at least one hydrogen atom which is reactive toward isocyanate groups, and
  • a5) 0-8% by weight of one or more nonionically hydrophilic compounds which have at least one isocyanate group or at least one group which is reactive toward isocyanate groups, the sum of components a1) to a5) being 100% by weight
    and
• b) 20-80 wt .-% of one or more carbonate-free, ionic group-containing polyurethane resins with a number average molecular weight (Mn) of 10,000 to 300,000 and an acid number of 5 to 50 in the form of an aqueous dispersion, obtainable by preparing an OH -Groups containing polyurethane prepolymers with an OH number of 5 to 75 and a number average molecular weight (Mn) of 5000 to 50,000, by reaction in an organic medium
  • b1) one or more isocyanate-reactive compounds in the form of
  • b1.1) 70 to 100 wt .-% of one or more polyester polyols and / or polyether polyols with a molecular weight of 400 to 6000, together with
  • b1.2) 0 to 30% by weight of one or more compounds different from b1.1) with at least two groups reactive with isocyanate, with a molecular weight of 60 to 400, the sum of components b1.1) and b1.2 ) Is 100% by weight with
  • b2) at least one compound with two isocyanate-reactive groups and at least one anionic group or one capable of forming anions, component b2) separately or in the form of a reaction product b2.1) from component b2) and one or more organic diisocyanates b2.2) can be used, the molar ratio of the groups of b2) reactive to isocyanate groups to the isocyanate groups of b2.2) being 1: 1.5 to 1: 2.5, and the reaction product b2.1) also in the presence of component b1 ) can be prepared and component b2) or the reaction product b2.1) can be used in such an amount that the finished polyurethane resins have the desired acid number, and also with
  • b3) one or more polyisocyanates with at least two free isocyanate groups per molecule, in such an amount that the molar ratio of the OH groups of component b1) to the NCO groups of components b2) and b3) is 1.01: 1 to 3 : 1 is
    whereupon the prepolymer obtained from b1), b2) and b3) is subjected to chain extension by reaction with before or after the partial or complete neutralization of groups which can be converted into ionic groups in the organic medium or after conversion into the water phase
  • b4) one or more polyfunctional isocyanates with a functionality of free NCO groups of at least 1.8, in proportions such that the finished polyurethane resins have the desired number average molecular weight,
    where the% by weight of components a) and b) each relate to the resin solids and add 100%.

5. The method according to claim 3, characterized in that the mixture of polyurethane dispersions is a combination of water-dilutable polyurethane dispersions

• c) 45-95% by weight of one or more polyurethanes, produced by free-radically initiated polymerization of polyurethane macromonomers containing carboxyl, phosphonic or sulfonic acid groups and lateral vinyl groups and in a solvent-based unsaturated monomer copolymerizable with the polyurethane macromonomer, optionally in the presence of further copolymerizable unsaturated monomers, in the form of an aqueous dispersion and
• d) 5-55% by weight of the urea group-free polyurethane resins containing ionic groups mentioned in claim 4 with a number average molecular weight (Mn) of 10,000 to 300,000 and an acid number of 5 to 50 in the form of an aqueous dispersion.

6. The method according to any one of the preceding claims, characterized in that that in the basecoat as component B) hydroxy-functional polyurethane, Polyacrylate and / or polyester resins with an OH number of 25 to 250 mg KOH / g and a number average molecular weight (Mn) of 1000 to 500,000 be used. 7. The method according to claim 6, characterized in that component B is one or more anionically modified hydroxy-functional polyurethane resins having an OH number of 25 to 250 mg KOH / g and a number average molecular weight of 1000 to 10,000, obtainable by

• 1) Preparation of a precursor containing NCO groups
  • 1a) at least one compound with two isocyanate-reactive groups and at least one anionic or anion-forming group,
    and / or one or more compounds having at least one pendant, hydrophilic chain with ethylene oxide units and two groups which are reactive with isocyanate, and from
  • 1b) one or more aliphatic or cycloaliphatic diisocyanates, optionally together with one or more aliphatic or cycloaliphatic diisocyanates with at least one pendant hydrophilic chain with ethylene oxide units,
• 2) Production of a polyester containing OH groups
  • 2c) one or more polyalcohols,
  • 2d) one or more dicarboxylic acids,
  • 2e) optionally one or more fatty acids and
  • 2f) optionally one or more polyols with at least one pendant hydrophilic chain with ethylene oxide units, and
• 3) subsequent reaction of the products obtained under I) and 2), optionally in the presence of one or more monoisocyanates with a hydrophilic chain with ethylene oxide units, in such proportions that the OH groups of the precondensate obtained under 2) are in excess over the NCO- There are groups.

8. The method according to any one of the preceding claims, characterized in that it is carried out for painting plastics with surface structure becomes. 9. The method according to any one of the preceding claims, characterized in that it is carried out for car refinishing.