DE19628361A1 - Multi-coat painting, especially for cars - Google Patents

Abstract

A process for applying several coats of paint to an electrically conductive substrate, by applying (1) an electrophoretic primer coat, stoving the primer, directly applying (2) a coloured and/or special-effect coat and then applying (3) further overcoats as required. Coating composition (2) comprises an aqueous coating material containing pigments and a binder consisting of (A) 50-85 wt% hybrid binder based on (a1) polyesters and (a2) (meth)acrylic copolymers with a hydroxyl (OH) number of 100-350 mg/KOH/g and an acid number of 20-60 mg KOH/g, (B) 0-20 wt% binder other than (A) and (C) 15-50 wt% free or blocked polyisocyanate and/or triazine-based crosslinker(s) which react with the OH groups in (A) to form ether and/or ester groups. At least 50 wt% copolymer (a2) is produced in presence of at least 20 wt% of polyester (a1).

Description

The invention relates to a method for producing a multilayer paint conductive, z. B. metallic substrates, especially for automotive painting.

Today's, high-quality automotive OEM coatings exist in generally from an electrophoretically applied primer, a subsequent filler layer and one subsequently applied Two-layer paint from color and / or effect Basecoat and a protective surface sealing Clear coat.

For example, to reduce solvent emissions water-thinnable filler paints, so-called hydrofillers, entrance to the found modern automotive paintwork.

The object of the invention is a method for producing a Multi-layer lacquers containing hydraulic filler layer, in particular of automotive paintwork with compared to the prior art comparable or improved overall property level, in particular but with an improved optical surface quality to provide with regard to course and topcoat level.

It has been shown that this object is surprisingly achieved can be by the method forming an object of the invention for multi-layer painting by electrophoretic application of a Priming on a conductive substrate, baking the obtained Primer layer, application of a hydraulic filler layer and one color and / or effect top coat or a color and / or preferably effect-giving two-coat paint consisting of a Basecoat and a clear coat, which is characterized by that the hydro filler coating agent contains as binder:

• A) 50 to 85 wt .-% of one or more hybrid binders on the  Base of polyesters as well (Meth) acrylic copolymers with a hydroxyl number from 100 to 350 mg KOH / g and an acid number of 20 to 60 mg KOH / g,
• B) 0 to 20% by weight of one or more of A) different Binder,
• C) 15 to 50 wt .-% of one or more free or blocked Polyisocyanates and / or one or more with the hydroxyl groups of component A) below Crosslinking ether and / or ester group formation Triazine-based components,

the sum of components A), B) and C) being 100% by weight Binder solid supplements, and wherein at least 50 wt .-% of (Meth) acrylic copolymers of component A) in the presence of at least 20% by weight of the polyester or components A) have been produced.

It has been shown that the method according to the invention is special favorable for motor vehicle bodies or their parts is feasible and it allows multi-layer painting, in particular To produce multi-layer paintwork, which is characterized by a outstanding optical surface quality.

Within the method according to the invention, all of them per se known anodically or cathodically depositable electrocoat materials for Generation of an electrophoretically applied primer used will. It is e.g. B. to aqueous coating agents with a Solids up to 50% by weight, for example 10 to 50% by weight, in particular 10 to 30% by weight. The solid is formed from for Electrocoating usual binders, the ionic groups or groups which can be converted into ionic groups and, if appropriate, for groups capable of chemical crosslinking, and if appropriate existing crosslinkers, pigments, fillers and / or paint Additives. The ionic or convertible groups can be anionic or convertible into anionic groups, e.g. B. acidic groups, such as -COOH groups or cationic or cationic  Groups transferable, e.g. B. basic groups, such as amino groups or Ammonium, e.g. B. quaternary ammonium groups, phosphonium and / or Be sulfonium groups. Preferred are binders with basic or cationic groups. Nitrogen-containing ones are particularly preferred basic groups. These groups can be quaternized or they are at least partially with a usual Neutralizing agent, an acid, e.g. B. an organic Monocarboxylic acid, such as B. formic acid or acetic acid, in cationic Groups convicted.

To produce the electrocoat layer, for example Anodically depositable customary anionic groups Electro dip coating binders and paints (ATL) can be used. It are, for example, binders based on polyesters, Epoxy resins, poly (meth) acrylates, maleate oils or polybutadiene oils with a weight average molecular weight of, for example, 300 to 10,000 and an acid number of 35 to 300 mg KOH / g. Wear the binders e.g. B. -COOH, -SO₃H and / or -PO₃H₂ groups. The resins can after Neutralization of at least some of the acidic groups in the Water phase are transferred. The binders can be self-crosslinking or be cross-linked. The varnishes can therefore also be customary Crosslinkers included, e.g. B. triazine resins, crosslinkers, the contain groups capable of transesterification or blocked polyisocyanates. Specific examples of such in the process according to the invention Anodically depositable anionic groups that can be used Electrodeposition paint binders and paints (ATL) are e.g. B. in DE-A-28 24 418 described.

However, cathodic are preferred in the process according to the invention Electrophoretic coatings (KTL) based on cationic or basic Binder used. Such basic resins are, for example resins containing primary, secondary or tertiary amino groups, the Amine numbers e.g. B. 20 to 250 mg KOH / g. The weight average of the Molar mass (Mw) of the base resins is preferably 300 to 10,000. Examples of such base resins are amino (meth) acrylate resins, Amino epoxy resins, amino epoxy resins with terminal double bonds, Amino epoxy resins with primary OH groups, aminopolyurethane resins,  amino group-containing polybutadiene resins or modified epoxy resin Carbon dioxide-amine reaction products. These base resins can be self-crosslinking or they are used with known crosslinkers Mixture used. Examples of such crosslinkers are those Aminoplast resins, blocked polyisocyanates known to those skilled in the art, Crosslinkers with terminal double bonds, polyepoxide compounds or Crosslinkers containing groups capable of transesterification.

Examples of cathodic used in the invention Dip resins (KTL) baths base resins and crosslinking agents are in EP- A-0 082 291, EP-A-0 234 395, EP-A-0 227 975, EP-A-0 178 531, EP-A-0 333 327, EP-A-0 310 971, EP-A-0 456 270, US 3 922 253, EP-A-0 261 385, EP- A-0 245 786, DE-A-33 24 211, EP-A-0 414 199 and EP-A-0 476 514 described.

Such resins can be used alone or in a mixture. Prefers so-called "non-yellowing" -KTL systems are used, the one Yellowing or discoloration of the multi-layer coating when baked avoid. For example, it is by means of special selected blocked polyisocyanate crosslinking KTL systems, such as described for example in EP-A-0 265 363.

In addition to the base resins and any crosslinking agents present Can the electrocoat (ETL) coating agent pigments, fillers and / or conventional paint additives. As pigments and fillers come the usual inorganic and / or organic pigments and Fillers in question. Examples are carbon black, titanium dioxide, Iron oxide pigments, phthalocyanine pigments, quinacridone pigments, kaolin, Talc or silicon dioxide.

The pigments can be dispersed into pigment pastes, e.g. More colorful Use of known paste resins. Such resins are known to the person skilled in the art common. Examples of paste resins that can be used in KTL baths are in EP-A-0 183 025 and EP-A-0 469 497.

The usual additives, in particular, are possible as additives are known for ETL coating agents. Examples of this are the  Common wetting agents, neutralizing agents familiar to those skilled in the art, Leveling agents, catalysts, corrosion inhibitors, anti-foaming agents, Solvents, light stabilizers, if necessary in combination with Antioxidants.

Electrophoretic Deposition in a known manner primers on the electrical conductive, e.g. B. applied metallic substrate, for example in a dry layer thickness of 15 to 30 µm. If necessary, then residues of paint that do not adhere firmly can be rinsed off. The received Paint layer is then at elevated temperature, for example up to 180 ° C, baked and chemically cross-linked, before one according to the invention Hydro filler layer and a color-providing top coat or a color and / or preferably effect-giving two-layer coating consisting of a basecoat and a clearcoat are applied. Of the Hydrofüller contains the combination of Components A), B) and C) as binders.

The binders A) are referred to as hybrid binders because they are based on Polyesters and (meth) acrylic copolymers are based. The polyester can for example have a calculated molecular weight of 200 to 3000 exhibit. For example, they have a hydroxyl number of 100 to 600 mg KOH / g and an acid number of 0 to 50 mg KOH / g. You can for example as an oligoester with a calculated molecular weight from 200 to 1000 or as polyester with a calculated Molecular weight from 1000 to 3000 can be used. The Hybrid binders have a hydroxyl number of 100 to 350, preferably 120 to 200 mg KOH / g and an acid number of 20 to 60, preferably of 25 up to 40 mg KOH / g and are preferably composed of 30 to 95% by weight (Meth) acrylic copolymer and 5 to 70% by weight of oligo- and / or polyester, preferably only oligoester. They are available through in the presence of a or more hydroxy-functional oligo- and / or polyester carried out radical polymerization of one or more esters unsaturated carboxylic acids with hydrophobic and hydrophilic components, where a) the hydrophobic portions on monomeric esters of unsaturated Carboxylic acids with secondary OH groups, which are mixed with OH Group-free comonomers can be present and b) the hydrophilic ones  Portions on monomeric esters of unsaturated carboxylic acids with primary OH groups are based on the mixture with OH group-free comonomers can be present. The numerical ratio is from Components a) and b) derived from primary to secondary OH groups in the Copolymers preferably between 1: 1.5 to 1: 2.5. It will at least 50% by weight of the (meth) acrylic copolymers in the presence of at least 20% by weight of the oligo- and / or polyester produced.

The oligoesters which can be used, for example, are obtainable from Polycondensation of diols and / or polyols and polycarboxylic acids, preferably dicarboxylic acids, and / or their derivatives, if appropriate using one or more hydroxycarboxylic acids, one or more monoalcohols and / or monocarboxylic acids and they have a calculated molecular weight of 200 to 1000, preferably 300 to 600, a hydroxyl number of 100 to 600, preferably 200 to 500 mg KOH / g, and an acid number of 0 to 15, preferably 0 to 1.5 mg KOH / g.

The polyesters which can be used, for example, are obtainable from Polycondensation of diols and / or polyols and polycarboxylic acids, preferably dicarboxylic acids and / or their derivatives, optionally under Use of one or more hydroxycarboxylic acids, one or several monoalcohols and / or monocarboxylic acids and they have one calculated molecular weight from 1000 to 3000, preferably below 2000, a hydroxyl number of 100 to 400, preferably 150 to 250 mg KOH / g, and an acid number of 0 to 50, preferably 10 to 40, particularly preferably 20 to 35 mg KOH / g.

The oligo- and / or used in the production of component A) Polyesters can e.g. B. by condensation of one or more diols and / or polyols, optionally in the presence of one or several monoalcohols, with one or more polycarboxylic acids, preferably dicarboxylic acids and / or their derivatives and optionally one or more monocarboxylic acids and hydroxycarboxylic acids getting produced. The polycondensation takes place according to the usual, the Processes familiar to those skilled in the art, for example in the presence of customary ones Esterification catalysts and, for example, at elevated temperatures  from Z. B. 180 to 230 ° C in the melt.

Examples of usable polyols are those with more than two OH Groups such as aliphatic triols and tetrols with 2 to 6 Carbon atoms, such as trimethylolethane, trimethylolpropane, glycerol, 1,2,4-butanetriol, 1,2,6-hexanetriol and pentaerythritol. Also possible is one or more monofunctional alcohols, such as. B. Monoalkanols with, for example, 1 to 20 carbon atoms in the alkyl radical to be involved. Examples include methanol, ethanol, isopropanol, Lauryl alcohol and stearyl alcohol.

Examples of usable diols are aliphatic diols, such as. B. Ethylene glycol, propylene glycol (1.3 and 1.2), butanediol, hexanediol (1,6), neopentyl glycol, 2-butyl-2-ethyl-propanediol-1,3; Polyether glycols of ethylene and propylene with up to 6 Monomer units, such as diethylene glycol, triethylene glycol, Tetraethylene glycol and hexaethylene glycol; and cycloaliphatic diols such as 1,3-dimethylolcyclohexane and 1,4-dimethylolcyclohexane.

A preferred example of a usable hydroxycarboxylic acid is Dimethylol propionic acid.

Examples of polycarboxylic acids and the preferred dicabonic acids are Trimellitic acid, aliphatic saturated and unsaturated Dicarboxylic acids, such as. B. maleic acid, fumaric acid, succinic acid, Adipic acid, azelaic acid, sebacic acid; cycloaliphatic saturated and unsaturated dicarboxylic acids and aromatic dicarboxylic acids such as Phthalic acid, isophthalic acid, tetra- and hexahydrophthalic acid and Cyclohexanedicarboxylic acid (1,2; 1,3 and 1,4), itaconic acid and their possible anhydrides. It is also possible to use monofunctional carboxylic acids, such as. B. acetic acid, propionic acid, Benzoic acid or stearic acid.

The monomers a) and b) are used in such amounts that the Hybrid binder obtained on the basis of oligo- and / or Polyesters and (meth) acrylic copolymers have a hydroxyl number of 100 to 350, preferably 120 to 200 and an acid number of 20 to 60, preferably from 25 to 40 mg KOH / g.  

The in the present description and the claims The used expression "(meth) acrylic" is synonymous with "acrylic and / or Methacrylic ".

The binder component A) can be obtained by polymerizing the components a) and b) in the oligo- and / or polyesters will.

When the binder component A) is provided, at least 50% by weight, preferably over 70% by weight, of the total amount of (meth) acrylic Copolymers and preferably its total amount in the presence of at least 20% by weight, preferably over 30% by weight, particularly preferably over 40% by weight of the or the oligo- and / or polyester produced. Become several Oligo- and / or polyester used, these can be used in the Production of the (meth) acrylic copolymer as a mixture, or it can be used individually or a part of the oligo- and / or polyester and the rest will be added later. The The (meth) acrylic copolymers can be prepared by free radicals Polymerization is carried out by customary methods. In doing so at least 20% by weight, preferably over 30% by weight, particularly preferably over 40 wt .-% of the or the oligo- and / or polyester optionally in Mix with suitable organic solvents in the reaction vessel submitted, heated to the reaction temperature and at least 50 wt .-%, preferably over 70% by weight, particularly preferably the total amount of monomer mixture optionally containing free radical initiators for the synthesis of the (meth) acrylic copolymer metered. The any remaining amount of any Monomer mixture containing radical initiators for the synthesis of the (Meth) acrylic copolymer can be radical in the same way are polymerized, only organic solvent without portions of or the oligo- and / or polyester placed in the reaction vessel is heated to the reaction temperature and the procedure is then followed as described above. That by polymerizing the optionally remaining amount of the monomer mixture obtained (Meth) acrylic copolymers can in the presence of the or the oligo- and / or polyester synthesized (meth) acrylic copolymers  will.

For example, one can particularly preferably proceed in such a way that the Total amount of 5 to 70 wt .-% of or the hydroxy-functional Oligo- and / or polyester component A) is submitted and therein the total amount of 95 to 30% by weight of the or of the (meth) acrylic copolymers of component A) required unsaturated carboxylic acids with hydrophobic and hydrophilic components, based on components a) and b) defined above be polymerized. The parts by weight of Components a), b) and oligo- and / or polyester per 100 parts by weight. The proportions of components a) and b) are preferably so chosen that the number ratio of primary to secondary OH groups in the (meth) acrylic copolymer obtained (without taking the OH Groups of oligos and / or polyester) 1: 1.5 to 1: 2.5 is.

The (meth) acrylic copolymer is prepared as above described in the presence of at least subsets of the Oligo- and / or polyester, which are dissolved in organic solvents can be presented. As solvents that are also present in a mixture can, for example, be used as they are can be used for oligo and / or polyester resin synthesis; the oligo- and / or polyester can thus be used as a solution are presented, which was obtained in their manufacture. It can but other suitable solvents can also be used. For example Suitable paint solvents, such as those later used in hydraulic fillers can be used. Examples of solvents in their Presence carried out the preparation of the (meth) acrylic copolymer are glycol ethers, such as butyl glycol, butyl diglycol, Dipropylene glycol dimethyl ether, dipropylene glycol monomethyl ether, Ethylene glycol dimethyl ether, polyethylene glycol di-n-butyl ether; Glycol ether esters, such as ethyl glycol acetate, butyl glycol acetate, Butyl diglycol acetate, methoxypropyl acetate; Esters, such as butyl acetate, Amyl acetate; Ketones, such as methyl ethyl ketone, methyl isobutyl ketone, Cyclohexanone; Alcohols, such as ethanol, propanol, butanol, aromatic Hydrocarbons such as xylene, Solvesso 100 (registered trademark  for a mixture of aromatic hydrocarbons with a boiling range from 155 to 185 ° C), aliphatic hydrocarbons.

The hydrophobic portion a) of the (meth) acrylic copolymers of component A) is obtained by copolymerization of monomers based on esters unsaturated carboxylic acids such as (meth) acrylic acid, itaconic acid, Maleic acid, fumaric acid and crotonic acid with at least one secondary Hydroxyl group in the alcohol part in the presence of one or more oligo- and / or polyester. The alcohol component of the Contains ester monomers based on unsaturated carboxylic acids preferably 3 to 25 carbon atoms.

Examples of the hydrophobic monomers with secondary OH functions are: hydroxypropyl (meth) acrylate, adducts of glycidyl (meth) acrylate and saturated short- or long-chain fatty acids with C₁-C₂₀ alkyl radicals, e.g. B. acetic acid, propionic acid, butanoic acid, caproic acid, lauric acid, Palmitic acid, stearic acid, and adducts from Cardura E (glycidyl ester versatic acid) with unsaturated COOH-functional compounds, such as B. (meth) acrylic acid, itaconic acid, maleic acid, fumaric acid, Crotonic acid.

The hydrophilic portion b) of the (meth) acrylic copolymers of component A) is obtained by copolymerization of monomers based on esters unsaturated carboxylic acids such as (meth) acrylic acid, itaconic acid, Maleic acid, fumaric acid and crotonic acid with at least one primary Hydroxyl group in the alcohol part in the presence of one or more oligo and / or polyester. The alcohol component of the Ester monomers based on unsaturated carboxylic acids can for example have 2 to 18 carbon atoms.

Examples of the monomers for building up the hydrophilic portion of the Component A) are: hydroxyalkyl esters of (metha) acrylic acid with a primary OH group with C₂-C₃-hydroxyalkyl such as Hydroxyethyl (meth) acrylate and hydroxyalkyl esters of (meth) acrylic acid with a primary OH group with C₄-C₈-hydroxyalkyl such as. B. Butanediol mono (meth) acrylate, hydroxyhexyl (meth) acrylate, Hydroxyoctyl (meth) acrylate and reaction products of  Hydroxyethyl (meth) acrylate with caprolactone.

The hydrophilic components b) of the (meth) acrylic copolymers of component A) also contain carboxyl groups, for their introduction carboxyl-functionalized monomers are used, such as. B. (Meth) acrylic acid, itaconic acid and crotonic acid. More usable carboxyl-functionalized monomers are due to the addition of saturated aliphatic alcohols such as B. ethanol, propanol, butanol half esters produced on maleic anhydride.

In the production of the (meth) acrylic copolymers of component A) other comonomers are used which are free of OH groups. Examples include (cyclo) alkyl (meth) acrylates (alkyl and / or Cycloalkyl (meth) acrylates) such as ethylhexyl (meth) acrylate, Octyl (meth) acrylate, dodecyl (meth) acrylate, lauryl (meth) acrylate, Isobornyl (meth) acrylate, 4-tertiary butylcyclohexyl (meth) acrylate, Methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, Isobutyl (meth) acrylate, tertiary butyl (meth) acrylate, Cyclohexyl (meth) acrylate. Aromatic vinyl compounds, such as styrene and styrene derivatives such as vinyltoluene and p-methylstyrene as Comonomers can also be used. The proportions of the others Comonomers can be chosen so that the desired ones Specifications regarding molar mass, OH group ratio, OH number and Acid number can be achieved.

As mentioned, the (meth) acrylic copolymers are produced Component A) by copolymerization of components a) and b) in Presence of one or more oligo- and / or polyester. It deals is a radical copolymerization in which the amounts of Monomers and the oligo- and / or polyester are adjusted so that the desired specifications regarding molar mass, OH Group ratio, OH number and acid number can be achieved.

The polymerization is carried out, for example, at temperatures between 80 and 180 ° C, preferably carried out at 100 to 150 ° C.

The production takes place, for example, as a radical  Solution polymerization in the presence of one or more oligo- and / or polyester and a radical initiator, such as the person skilled in the art is known. Examples of radical initiators are peroxides such as di-tert-butyl peroxide, Dicumyl peroxide, dibenzoyl peroxide, Cumene hydroperoxide, tert-butyl hydroperoxide, tert-butyl perbenzoate, tert-butyl per-2-ethylhexanoate, cyclohexanone peroxide, Methyl isobutyl ketone peroxide, azo compounds, such as 2,2′-azo-bis (2,4- dimethylvaleronitrile), azo-bis-isobutyronitrile and C-C-cleaving Initiators such as B. Benzpinacol derivatives.

The polymerization initiators are generally described, for example, in an amount of 0.1 to 4% by weight, based on the weight of monomers, added. The monomers can also be separated in the polymerization or metered in at different times. The monomers or that Monomer mixture used can contain the radical initiators or the radical initiators can optionally be used for the monomer mixture added slightly delayed or added separately.

The radical polymerization can be carried out in a one-pot process Achieving a statistical distribution of hydrophobic and hydrophilic portions are carried out.

It can e.g. B. be worked so that all necessary monomers as well the initiator (s) mixed in a storage vessel and then over a period of z. B. 5 hours at z. B. 140 ° C the one or more optionally in a mixture with one or more Solvents present oligo- and / or polyesters with stirring be added. The resulting copolymers then have a statistical distribution of primary and secondary hydroxy as well the carboxyl groups.

However, it is also possible to use block polymerization to achieve (Meth) acrylic copolymers with hydrophobic and hydrophilic blocks perform. The block copolymers can be prepared in a conventional manner Working method. For example, initially Mixtures of hydrophobic monomers (possibly together with other comonomers) are polymerized, whereupon hydrophilic  Monomers (optionally with comonomers) metered in and further be polymerized. In practice it is possible, for example, first a mixture of hydrophobic, hydroxy-functional monomers, (Meth) acrylic acid esters and optionally z. B. vinyl aromatics meter in and then another mixture of hydrophilic, hydroxy-functional monomers, (meth) acrylic acid esters, vinyl aromatics and meter in carboxy-functional monomers.

Those which can be used in the process according to the invention Hydrofiller coating compositions can as component B) one or more of A) various binders in a proportion of up to 20% by weight, based on binder solids. Examples are from A) various anionic in the form of carboxyl groups and / or not stabilized ionically in the form of polyoxyalkylene groups (Meth) acrylic copolymer resins, polyester resins or also polyurethane resins. The binders different from A) can be pure thermoplastics or they can carry suitable hydroxyl groups for crosslinking. Under component B) in particular special pigment grind resins. An example of a in the hydraulic filler in the context of the present Paste resin preferably used according to the invention based on an anionic Stabilized polyurethane resin can be found in DE-A-40 00 889. In addition to components A) and C), the hydraulic fillers preferably contain as well as the special rubbing resins of the Component B) no further binders B).

Contain the hydrofillers which can be used in the process according to the invention as crosslinker component C) 15 to 50 wt .-%, based on the Binder solid, one or more free or blocked Polyisocyanates and / or one or more with the hydroxyl groups Component A) crosslinking with formation of ether and / or ester groups Triazine based components. The free or blocked Polyisocyanates and / or the triazine crosslinkers can be in the aqueous Phase dissolved or dispersed and / or dissolved in the binder phase or dispersed in the hydraulic fillers. Preferably contain the Hydrofillers which can be used in the process of the invention as Crosslinker component C) a crosslinker combination of one or several blocked polyisocyanates and one or more with the  Hydroxyl groups of component A) under ether and / or Triazine-based components crosslinking ester groups, preferably in a solid weight ratio of 20 to 60% by weight Parts of blocked polyisocyanate to 80 to 40 parts by weight Triazine crosslinker.

As polyisocyanates, individually or as a mixture in the Hydraulic fillers that can be used according to the invention in free or blocked form, any organic di- and / or polyisocyanates with aliphatic, cycloaliphatic, araliphatic and / or less preferably aromatically bound Isocyanate groups that are liquid at room temperature or by addition organic solvents are liquefied or in solution at 23 ° C generally a viscosity of 0.5 to 2000 mPa · s, preferably above 1 and below 1000 mPa · s, particularly preferably below 200 mPa · s exhibit. Preferred diisocyanates are those which are about 3 to about 36, in particular contain about 8 to 15 carbon atoms. Examples suitable diisocyanates are tolylene diisocyanate, Diphenylmethane diisocyanate and especially hexamethylene diisocyanate, Tetramethylxylylene diisocyanate, isophorone diisocyanate, Dicyclohexylmethane diisocyanate and cyclohexane diisocyanate.

Polyisocyanates which can also be used are those which Contain heteroatoms in the radical linking the isocyanate groups. Examples include polyisocyanates, the carbodiimide groups, Allophanate groups, isocyanurate groups, urethane groups, acylated Have urea groups or biuret groups. They preferably have Polyisocyanates have a higher isocyanate functionality than 2, such as for example by di- and / or trimerization of the above Diisocyanates made from uretdione or Isocyanurate type. Other examples are by implementing the above mentioned diisocyanates with water biuret groups containing polyisocyanates or by reaction with polyols produced low molecular weight urethane groups Polyisocyanates.

"Lacquer polyisocyanates" based, for example, are very suitable  of hexamethylene diisocyanate or of isophorone diisocyanate and / or Dicyclohexylmethane diisocyanate, especially those exclusively based on hexamethylene diisocyanate. Under "paint polyisocyanates" on These diisocyanates are based on the biuret, urethane, Derivatives of these containing uretdione and / or isocyanurate groups To understand diisocyanates.

Suitable polyisocyanates are also the known terminal ones Prepolymers containing isocyanate groups, as described in particular by Implementation of the above simple polyisocyanates, especially Diisocyanates with insufficient amounts of organic compounds at least two groups reactive towards isocyanate groups are accessible. At least two in total preferably come as such Compounds having amino groups and / or hydroxyl groups a number average molecular weight of 300 to 10,000, preferably 400 to 6000, for use. The corresponding ones are preferred Polyhydroxyl compounds, e.g. B. in polyurethane chemistry itself known hydroxypolyester, hydroxypolyether and / or hydroxyl-containing acrylate resins used. In these well-known The ratio of isocyanate groups to prepolymers corresponds to isocyanate-reactive hydrogen atoms 1.05 to 10: 1, preferably 1.1 to 3: 1, the hydrogen atoms preferably consisting of Hydroxyl groups originate. The type and proportions of the Production of the NCO prepolymers used starting materials are preferably chosen so that the NCO prepolymers an average NCO functionality of 2 to 4, preferably 2 to 3 and a number average molecular weight from 500 to 10,000, preferably from Have 800 to 4000.

It is also possible to use vinyl copolymers unsaturated monoisocyanates dimethyl-m-isopropenylbenzyl isocyanate as polyisocyanate, as described, inter alia, in DE-A-41 37 615 are described.

The polyisocyanates can be used as crosslinkers in free or blocked form be used in the hydraulic fillers. In the case of the blocked form are they with the usual, volatile,  can be split off again under the subsequent baking conditions Blocking agents blocked. Examples of these are CH-acidic Compounds such as acetylacetone or CH-acidic esters, such as. B. Alkyl acetoacetic acid, dialkyl malonate; (cyclo) aliphatic Alcohols, such as n-butanol, furfural, 2-ethylhexanol, cyclohexanol; Phenols such as cresol, tert-butylphenol; Dialkylamino alcohols such as Dimethylaminoethanol; Oximes such as methyl ethyl ketoxime, acetone oxime, Cyclohexanone oxime; Lactams such as epsilon-caprolactam or pyrrolidone-2; Imides such as phthalimide; Hydroxyalkyl esters, hydroxamic acids and their Esters, N-alkylamides such as methylacetamide, imidazoles such as 2-methylimidazole, Pyrazoles such as 2,3-dimethylpyrazole, triazoles. There can be mixtures of these Blocking agents are used. Preferred as a blocking agent CH-acidic esters and / or oximes are particularly suitable for the polyisocyanates Diethyl malonate, ethyl acetoacetate, acetone oxime and Butanone oxime.

The polyisocyanates can be the same or within a molecule various blocking agents. It can too Mixtures of differently blocked polyisocyanates can be used.

The free or blocked polyisocyanates can be used as such in the Production of the hydraulic filler can be added, for example, by Stir or emulsify. This can be the dissolved or dispersed Binder function as an emulsifier for the added Take over polyisocyanate. It can be beneficial if an emulsifier too Help is taken or if the free or blocked Polyisocyanates with a water-miscible organic solvent or Solvent mixture are prediluted. Are preferred especially when using free polyisocyanates Isocyanate inert solvents are used. examples are Solvents that do not contain active hydrogen, such as. B. Diethylene glycol diethyl ether, dipropylene glycol dimethyl ether, Butyl glycol acetate, butyl diglycol acetate, methoxypropylacetate or particularly preferably N-methylpyrrolidone.

Also suitable are hydrophilic, free or as above described blocked polyisocyanates by sufficient  Number of anionic groups and / or by terminal or lateral Polyether chains are stabilized in the aqueous phase. Examples for anionically and / or non-ionically stabilized, hydrophilic Polyisocyanates are described in EP-A-0 061 628, EP-A-0 206 059, EP-A-0 469 389, EP-A-0 510 438, EP-A-0 516 277, EP-A-0 540 985, EP-A-0 654 410, EP-A-0 680 983, DE-A 41 42 275. Water dispersible Polyisocyanates are e.g. B. from Bayer under the name Bayhydur® LS 2025 and LS 2032 sold as commercial products. Also these can be diluted with the solvents mentioned above.

If the polyisocyanates are used in free form, it is in the case of the hydraulic fillers which can be used in the process according to the invention Two component coating agent, d. H. the hydrofiller that is finished is stored separately from the free polyisocyanate. In case of If free polyisocyanates are used, they are preferably those per se Hydrofillers are only added to the finished hydraulic filler shortly before application. This can for example by means of a in the automotive OEM painting Conventional two-component mixing system take place or one uses for example a procedure as from EP-A-0 685 544 known.

With the formation of ether groups with the hydroxyl groups Component A) crosslinking components C) based on triazine are in particular conventional amine resins, such as alkylated Condensates by the reaction of aminotriazines and amidotriazines be produced with aldehydes. For example, it is by known technical processes in the presence of alcohols, such as Methanol, ethanol, propanol, butanol or hexanol with aldehydes, especially formaldehyde, condensed triazines such as melamine or Benzoguanamine.

For example, they are preferably customary as crosslinkers Melamine resins such as B. methyl etherified melamine resins such as Commercial products Cymel 325, Cymel 327, Cymel 350 and Cymel 370, Maprenal MF 927. Other examples of usable melamine resins are butanol or isobutanol etherified melamine resins such. B. the commercial products Setamin US 138 and Maprenal MF 610; mixed etherified melamine resins, the  are etherified with both butanol and methanol, e.g. B. Cymel 254, and in particular hexamethoxymethylmelamine (HMMM) such as. B. Cymel 301 or Cymel 303, the latter using an external network Acid catalyst such as B. may need p-toluenesulfonic acid. Such acid catalysts can optionally with amines or Epoxy compounds can be blocked ionically or non-ionically.

With the formation of ester groups with the hydroxyl groups Components A) crosslinking components C) based on triazine transesterification crosslinking agents, in particular with the formation of Urethane groups (carbamic acid ester groups) with the hydroxyl groups of Components A) reacting transesterification crosslinkers, such as preferably tri (alkoxycarbonylamino) triazine, as described in EP-A-0 604 922 is described.

Components A) and C) and optionally B) can, for example mixed together, neutralized and emulsified. It is also possible to first component A) and optionally B) neutralize and then with the crosslinker component C) mix, whereupon water is added.

In practice, for example, one can proceed in such a way that a solvent-containing component A) plus optionally B) optionally is largely freed from solvents, preferably by distillation under reduced pressure. Then partially or with bases completely neutralized. Bases customary in paint can be used for this such as ammonia or organic amines such as triethylamine, N- Methylmorpholine, amino alcohols such as dimethylisopropanolamine, Dimethylethanolamine, triethanolamine, 2-amino-2-methylpropanol-1. Then can also component C) into components A) plus if necessary, B) are metered in before then into the Resin mixture of demineralized water is metered in, for example under intensive mixing. The dispersion can be prepared by Warming the water phase are supported. As mixing units are for example high-speed stirrers or rotor / stator mixers suitable. It is also possible to use high pressure or to improve ultrasonic homogenizers. The procedure can  be carried out continuously or discontinuously.

It is also possible to add the hybrid binder A) plus if appropriate B) if necessary, after extensive removal of solvents or to neutralize completely with bases and with water too dilute before the crosslinker components C) are added.

Alternatively, components A), optionally B) and optionally containing C) preferably at least largely from Solvent-free binders using a conventional, not ionic emulsifier can be emulsified. This happens e.g. B. by Homogenize the binder together with the or the crosslinkers C) and one or more nonionic emulsifiers, optionally with heating, for example to temperatures of 30 to 80 ° C, e.g. B. 60 ° C. Such a mixture can be in a conventional Homogenization device are emulsified. examples for this are Rotor / stator homogenizers with speeds of for example 8000 to 10000 revolutions per minute. The emulsifiers are for example in amounts of 3 to 30 wt .-% based on Binder solid, used.

The hydraulic fillers which can be used in the process according to the invention can Hydroxy-functional reactive diluents in a proportion of up to 20 wt .-% based on binder solids, contained, per se are water soluble or by means of external emulsifiers or by Emulsifier effect of the water-dilutable binder in the aqueous Phase have been transferred. These are connections with a number average molecular weight (Mn) below 500, preferred below 300 and an OH functionality of at least 2, for example preferably between 2 and 4. Examples of suitable Hydroxy-functional reactive diluents are alkanediols with 2 to 8 Carbon atoms, glycerin, optionally hydrogenated castor oil, Trimethylolpropane, pentaerythritol, sorbitol, mannitol and the above Number Average Molecular Weight Restrictions sufficient ethoxylation and / or propoxylation products of these Polyalcohols.  

Furthermore, those used in the process according to the invention Hydrofiller contain polymer microparticles known to those skilled in the art. It cross-linked or uncross-linked microparticles can be used. Examples of such polymer microparticles are in EP-A-0 038 127 and EP-A-0 234 362.

The hydraulic fillers may also contain paint additives, for example rheology-influencing agents such as highly disperse Silicic acid, inorganic layered silicates or polymers Urea compounds. Also act as thickeners, for example water-soluble cellulose ethers such as hydroxyethyl cellulose, Methyl cellulose or carboxymethyl cellulose, as well as synthetic Polymers with ionic and / or associative groups such as Polyvinyl alcohol, poly (meth) acrylamide, poly (meth) acrylic acid, Polyvinyl pyrrolidone, styrene-maleic anhydride or ethylene Maleic anhydride copolymers and their derivatives or also hydrophobic modified ethoxylated polyurethanes or polyacrylates.

Anti-settling agents, leveling agents, catalysts, Light stabilizers (for example of the HALS type, of the benzotriazole type, Microtitanium dioxide), anti-foaming agents, such as silicone-containing Compounds, wetting agents and adhesion-promoting substances are used will. Known paste resins are also understood as wetting agents, as described for example in DE-A-40 00 889, which for better dispersing and grinding of the pigments can be used can. Water-insoluble additives can, for example, before Conversion into the aqueous phase can be mixed with the binder.

The hydrofillers can be used in water-miscible paint solvents Amounts of, for example, preferably less than 20% by weight, e.g. B. 5 to 15 % By weight. Water-immiscible solvents can also contain be. The solvents can be made from the binder components A) and optionally B) or from the crosslinking component C) or they are added separately. Examples of solvents are glycols, for Example ethylene glycol, propylene glycol and their oligomers; Glycol ethers, such as ethoxypropanol, butyl glycol, butyl diglycol, Dipropylene glycol dimethyl ether, dipropylene glycol monomethyl ether,  Ethylene glycol dimethyl ether, polyethylene glycol di-n-butyl ether; Glycol ether esters, such as ethyl glycol acetate, butyl glycol acetate, Butyl diglycol acetate, methoxypropyl acetate; Esters, such as butyl acetate, Amyl acetate; Ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, Cyclohexanone; Alcohols such as ethanol, propanol, butanol; N- Methyl pyrrolidone; aromatic hydrocarbons such as xylene, Sovesso 100 (registered trademark for a mixture of aromatic Hydrocarbons with a boiling range of 155 to 185 ° C), aliphatic hydrocarbons.

The hydrofillers contain color and / or effect pigments and / or coloring absorption pigments and optionally fillers, they preferably contain no effect pigments. The is preferred Pigmentation of the hydraulic filler on the color of the subsequently applied applied one-coat topcoat or basecoat, d. H. preferably come the shades of the hydraulic filler and Single-coat topcoat or the basecoat close to each other or the color tones are particularly preferably even the same.

Examples of effect pigments are usually the platelet-shaped ones pigments used in effect paints, such as metal pigments, Mica pigments, microtitanium oxide and graphite effect pigments, platelet-shaped iron oxide (micaceous iron oxide), Molybdenum disulfide pigments, platelet-shaped copper thalocyanine pigments and bismuth oxychloride platelets, coated glass flakes, and Effect pigments that have a strong color flop, especially on dark ones Develop substrates.

The effect pigments, as a powder or in the form of a commercially available Paste may be present, are generally preferred at first water-dilutable organic solvents and additives processed into a paste. It can be useful at Production of the paste water-dilutable binder and / or Add paste resins. Care must be taken that the platelet-shaped effect pigments are not mechanical when mixed to be damaged.  

Examples of coloring absorption pigments and / or fillers can be organic or inorganic in nature are titanium dioxide, Iron oxide pigments, carbon black, silicon dioxide, barium sulfate, talc, Azo pigments, phthalocyanine pigments, quinacridone pigments, diketo Pyrrolopyrrole pigments, perylene pigments, indanthrone pigments.

The coloring absorption pigments and / or fillers are in the generally in part of the non-aqueous or already in the aqueous Phase transferred binder component A) rubbed. Preferably can the grinding also in a special component B) water-thinnable paste resin happen. An example of an im Hydrofiller preferred paste resin based on an anionic Stabilized polyurethane resin can be found in DE-A 40 00 889. Das Grinding is carried out in conventional units known to those skilled in the art. Then with the remaining portion of the aqueous binder or of the aqueous paste resin for finished pigment pigment grinding completed.

The hydrofillers used in the process according to the invention have preferably a solids content of 15 to 55% by weight, particularly preferably from 20 to 50% by weight. The ratio of pigment to Solid resin content (solid binder from components A), B) and C)) in the hydraulic fillers is, for example, 0.03: 1 to 2.5: 1, particularly preferably 0.06: 1 to 2: 1, in each case based on the Solid weight.

The hydrofillers can be burned onto the branded by customary methods electrophoretically applied primer. Prefers they are sprayed in a dry film thickness of for example 25 to 50 μm, preferably 30 to 40 μm, for example by compressed air spraying, airless spraying, high rotation, preferably by electrostatic spray application (ESTA), in particular through electrostatically supported high-speed application.

After the application, the hydraulic filler layer can be baked, which in usually takes place with one-component systems, for example with Temperatures up to 165 ° C before changing the hue of the  Multi-layer coating determining coating layer, for example from a one-coat topcoat or preferably a basecoat, is painted over. Especially if it is the Crosslinker component C) in the hydraulic filler is free polyisocyanate, what corresponds to a two-component system can be the following, the The color of the multi-layer coating also determines the top coat layer known wet-on-wet processes are applied, d. H. after the Hydraulic filler layer has been flashed off briefly, e.g. B. at temperatures up to 80 ° C.

The hydraulic filler layer is provided with a color and / or effect Top coat or preferably with a color and / or preferred effect-giving two-layer coating consisting of a basecoat and provided with a clear coat.

In the method according to the invention, the Color-imparting topcoats based on this purpose organic solvents or water-based in one Dry layer thickness of for example 30 to 80 microns applied and branded.

However, preference is given to coloring and / or effects which are known per se Two-coat paint applied, consisting of a base and a Clear coat layer exist.

As basecoat coating agents are used as they are usually for the production of basecoat / clearcoat Two-coat paints are used and in large numbers are known for example from the patent literature.

The basecoats can be physically drying or with training covalent bonds can be crosslinked. For those under training basecoats that crosslink covalent bonds can be self- or third-party networking systems.

The color and / or Effect basecoats are liquid coating agents. It can be  act single- or multi-component coating agents, are single-component prefers. It can be systems based on organic solvents act or are preferably waterborne basecoats whose Binder systems in a suitable manner, e.g. B. anionic, cationic or are non-ionic, stabilized.

In the process according to the invention for the production of the third Coating layer usable basecoat coating agents to conventional paint systems that use one or more common base resins contain film-forming binders. You can, if the base resins are not self-crosslinking or self-drying, if necessary also Crosslinker included. Both the base resin component and the Crosslinker components are not subject to any restrictions. The Binder / crosslinker systems of the basecoats can be of the same quality or preferably different from those of the hydraulic filler. As Film-forming binders (base resins) can, for example, be polyester, Polyurethane and / or (meth) acrylic copolymer resins can be used.

In the case of the preferred waterborne basecoats are preferred Contain polyurethane resins, particularly preferably at least one Share of 15 wt .-% based on the solid resin content of Water-based paint. The selection of the crosslinkers that may be included is not critical, it depends on the functionality of the Base resins, d. H. the crosslinkers are selected in the usual way, so that they are reactive, complementary to the functionality of the base resins Have functionality. Examples of such complementary Functionalities between base resin and crosslinker are: Hydroxyl / methylol ether, hydroxyl / free isocyanate, hydroxyl / blocked Isocyanate, carboxyl / epoxy. If compatible with one another, can also several such complementary functionalities in one basecoat coexist. The possibly in the basecoats Crosslinkers used can be present individually or in a mixture.

Contain the basecoats used in the process according to the invention in addition to the usual physically drying and / or chemically crosslinking binders inorganic and / or organic colored pigments  and / or effect pigments, e.g. B. titanium dioxide, iron oxide pigments, carbon black, Azo pigments, phthalocyanine pigments, quinacridone pigments, Metal pigments, e.g. B. made of aluminum, coated mica, Graphite effect pigments, platelet-shaped iron oxide, platelet-shaped Copper phthalocyanine pigments. The basecoats preferably contain Effect pigments.

It is preferred if the hydraulic filler and one-coat topcoat or Hydrofillers and basecoat with respect to each other in terms of their color tones are coordinated, d. H. especially close or even close have the same colors.

The basecoats can also contain customary paint additives, such as e.g. B. fillers, catalysts, leveling agents, anti-cratering agents or in particular light stabilizers, if appropriate in combination with Antioxidants.

Examples of solvent-based basecoat systems, which in processes according to the invention can be found in DE A 37 15 254, DE-A 41 15 948, DE-A 42 18 106, EP-A-0 289 997, EP-A-0 393 609 and WO-91 00 895.

Examples of those which can preferably be used in the process according to the invention Waterborne basecoat systems can be found in DE-A-29 26 584, DE-A-36 28 124, DE-A-38 41 540, DE-A-39 03 804, DE-A-39 15 459, DE-A-40 01 841, DE-A-40 09 857, DE-A-40 11 633, DE-A-41 07 136, DE-A-41 22 266, EP-A-0 089 497, EP-A-0 226 171, EP-A-0 228 003, EP-A-0 287 144, EP-A-0 297 576, EP-A-0 301 300, EP-A-0 353 797, EP-A-0 354 261, EP-A-0 401 565, EP-A-0 424 705, EP-A-0 422 357, EP-A-0 512 524, EP-A-0 581 211, EP-A-0 584 818, EP-A-0 678 536 and WO 95 28 429.

The basecoats can be applied using customary methods. They are preferred in a dry layer thickness of, for example, 10 applied to 40 microns, for example by spraying, such as Compressed air spraying, airless spraying, high rotation, preferably through electrostatic spray application (ESTA), especially by electrostatic high rotation job.  

After application, the basecoat can be preferred Waterborne basecoat to be dried or baked before use is varnished with a clear varnish. The clear coat is preferred in the known wet-on-wet method applied, d. H. after the Basecoat has been flashed off briefly, e.g. B. at temperatures of 20 up to 80 ° C. The basecoat is coated with a conventional liquid Clear varnish or powder clear varnish (in this case it can be for example, a dry-on-wet application) in one Dry layer thickness from, for example, 30 to 80, preferably from 30 to 60 µm overcoated. The clear coat can be wet-on-wet or Dry-on-wet application together with the basecoat Temperatures of up to 160 ° C, for example, are baked. Here the drying conditions of the top coat layer (basecoat and clear coat) according to the clear coat system used.

As a clear coat, all known or transparent are basically pigmented coating agent suitable. It can be one or act multi-component clear lacquer coating agents. You can be solvent-free (liquid or as a powder clear coat), or it can are systems based on solvents or are are water-thinnable clear coats, whose binder systems in suitably, e.g. B. anionic, cationic or non-ionic, are stabilized. With the water-borne clear lacquer systems it can are water-soluble or water-dispersed systems, for example emulsion systems or powder slurry systems, as in EP-A- 0 652 264. The clear coating compositions harden e.g. B. when baking at temperatures of up to 160 ° C, for example chemical crosslinking.

The clear lacquers which can be used in the process according to the invention are concerned it is usual clearcoat coating agents, the one or more usual Contain base resins as film-forming binders. You can if the base resins are not self-crosslinking, if necessary also Crosslinker included. Both the base resin component and the Crosslinker components are not subject to any restrictions. As Film-forming binders (base resins) can, for example, be polyester, Polyurethane and / or poly (meth) acrylate resins can be used. The  Selection of any crosslinker that is included is not critical to them depends on the functionality of the base resins, d. H. the crosslinker are selected so that they are one for the functionality of the base resins have complementary, reactive functionality. Examples of such Complementary functionalities between base resin and crosslinker are: Carboxyl / epoxy, hydroxyl / methylol ether, hydroxyl / free isocyanate, Hydroxyl / blocked isocyanate, (meth) acryloyl / CH-acidic group. Provided mutually compatible, several such complementary ones can also be used Functionalities are present side by side in a coating agent. The if necessary, crosslinking agents contained in the cover agents individually or in a mixture.

In addition to the chemically crosslinking binders and, if appropriate Crosslinkers can be used in the process according to the invention Clear varnish additives, such as. B. catalysts, leveling agents, Dyes, but especially rheology control agents such as microgels, NAD (= non-aqueous dispersions), disubstituted ureas ("sagging control agents "), and light protection agents, if necessary in combination contain with antioxidants.

Specific examples for one (1K) and two-component (2K) are not aqueous clear lacquer systems which in the process according to the invention as Clear varnish can be used can be found in DE-A-38 26 693, DE-A- 40 17 075, DE-A-41 24 167, DE-A-41 33 704, DE-A-42 04 518, DE-A-42 04 611, EP-A-0 257 513, EP-A-0 408 858, EP-A-0 523 267, EP-A-0 557 822, WO 92 11 327.

Special examples for one (1K) or two-component (2K) Water-clear lacquer systems used as clear lacquer in the process according to the invention can be used can be found in DE-A-39 10 829, DE-A-40 09 931, DE-A-40 09 932, DE-A-41 01 696, DE-A-41 32 430, DE-A-41 34 290, DE-A-42 03 510, EP-A-0 365 098, EP-A-0 365 775, EP-A-0 496 079, EP-A-0 546 640.

Specific examples of powder clearcoat systems in the invention Processes which can be used as clear lacquer can be found in EP-A-0 509 392, EP-A-0 509 393, EP-A-0 522 648, EP-A-0 544 206, EP-A-0 555 705, DE-A-42 22 194, DE-A-42 27 580.  

The transparent coating can be in a single layer or in shape of multiple layers from the same or from several different transparent coating agents can be applied. The is expedient transparent coating layer, however, from only one Clear coating agent applied.

Electrical serve as the substrate for the method according to the invention conductive, e.g. B. metallic substrates. Particularly suitable are, for. B. Automobile bodies or parts thereof, they can be made from pre-treated or untreated metal or with an electrically conductive Layer provided metal. The first one is on these substrates Coating layer, especially in the form of a Corrosion protection primer, electrophoretically in the usual way and in a usual dry layer thickness of ETL primers for example 15 to 30 microns deposited and baked.

On the substrate provided with the burned-in ETL layer second coating layer from the preferably in color to the hue of Subsequent coating layer adapted hydraulic filler preferably in one Spraying in a dry layer thickness of 25 to 50, preferably 30 applied up to 40 µm. Examples of suitable spray application processes are compressed air sprayers, airless sprayers or preferred electrostatic spraying (ESTA), being electrostatic Rotary spraying is the particularly preferred application method represents. After a short flash-off time, preferably with increased Temperatures up to 80 ° C, the hydraulic filler layer is usually baked at temperatures up to 165 ° C, preferably up to 140 ° C or in In the case of a hydraulic filler, the free polyisocyanate as Contains crosslinker component C), preferably only flashed off. After that the single-coat topcoat is applied in one Dry layer thickness of for example 30 to 80 microns, preferably 30 to 60 µm. For example, the baking temperature is for Top coat between 80 and 160 ° C. However, preference is given to the Hydrofiller layer a basecoat layer, preferably from a Effect basecoat applied. After briefly flashing off the basecoat, preferably at elevated temperatures up to 80 ° C Clear coats in the preferred wet-on-wet process in one for  Clear coat layers usual dry layer thickness of 30, for example to 80 microns, preferably 30 to 60 microns. Basecoat and clear coat are preferably baked together. For example, the Baking temperature when baking the basecoat and Clear coat between 80 and 160 ° C, preferably below 140 ° C. If necessary, further layers of clear lacquer from the same or of which various clear lacquer coating agents before or after Branding can be applied.

The method according to the invention can be used successfully for Initial vehicle painting can be used. The is also possible Application of the process in the field of car refinishing. The produced with the inventive method Multicoat paint systems meet the current requirements in automotive painting, especially its optical Surface quality is excellent. Course and topcoat level are improved compared to conventional, comparable hydraulic filler layers containing multi-layer coatings of the prior art.

Example 1 (Preparation of an Oligoester)

336.7 g trimethylolpropane, 366.8 g adipic acid and 197 g hexanediol are in catalysis of hypophosphorous acid at 180 to 230 ° C in the melt is esterified to an acid number of 20, then condensed under vacuum to an acid number below 1.5 mg KOH / g. The The hydroxyl number of the oligoester obtained was 460 mg KOH / g.

Example 2 (Preparation of an Oligoester)

534.2 g of hexanediol and 464.8 g of hexahydrophthalic anhydride are added Catalysis of hypophosphorous acid at 180 to 230 ° C in the melt esterified to an acid number of 4.5 mg KOH / g. The hydroxyl number of the obtained oligoester was 185 mg KOH / g.

Example 3 (Preparation of an aqueous hybrid binder)

200 g of butyl diglycol, 39 g of the oligoester from Example 2 and 208 g of the  Oligoesters from Example 1 are introduced and to 144 ° C. with stirring heated. A mixture of 378 g of an adduct of Acrylic acid to the glycidyl ester of versatic acid (manufactured by Reaction of 271 g glycidyl ester of versatic acid with 107 g Acrylic acid until the epoxy groups are completely consumed), 31 g Isobutyl acrylate, 38 g lauryl acrylate, 100 g hydroxyethyl acrylate, 196 g Styrene, 5 g ditertiary butyl peroxide and 14 g tertiary butyl peroctoate in metered in over a period of 5 hours. Then at 144 ° C there is still 2 Postpolymerized for hours. The polymer solution thus obtained is with Dimethylethanolamine and deionized water at 60 ° C with stirring a degree of neutralization of 50% and a solids content of 53 % By weight.

Example 4 (Production of a silver-colored multi-layer coating by the process according to the invention)

25.3 parts of the aqueous hybrid binder are placed under the dissolver from Example 3, 3.8 parts of hexamethoxymethylmelamine and 12.3 parts of one 75% by weight solution of an isocyanurate masked with butanone oxime Polyisocyanate based on hexamethylene diisocyanate in Dipropylene glycol dimethyl ether with a latent NCO content of the solution of 11%, 3 parts butyl diglycol and 5.5 parts deionized water mixed. There are 30.7 parts of an aqueous white pigment paste Basis of the aqueous polyurethane resin according to the example from DE-A-40 00 889 (Pigment / binder weight ratio 5.5: 1, solids content 65.8 Wt .-%) and 3.5 parts of a talc-containing aqueous filler paste based on the aqueous polyurethane resin according to the example from DE-A-40 00 889 (Filler / binder weight ratio 1.8: 1, solids content 47.1% by weight) and 1.5 parts of a customary leveling agent added. Then with 0.4 parts of dimethylethanolamine and 14 Dilute parts of deionized water. You get a white one Hydro filler.

With commercially available used in automotive OEM painting cathodic electrodeposition paint (KTL, 18 fan Dry layer thickness) precoated body panels are hanging in 30 µm dry film thickness with the white hydro filler electrostatically painted. After 5 minutes flash off at 80 ° C is 15 minutes at 165 ° C branded.  

6 parts of the aqueous polymer dispersion are placed under the dissolver from DE-A-36 28 124, preparation example 1, 16 parts of aqueous Polyurethane dispersion from DE-A-42 24 617, preparation example 2 and 17.5 parts of deionized water mixed. Then 6.5 Parts of an acid neutralized with dimethylethanolamine Acrylate thickener, 2 parts of wetting agent and 2 parts of butyl glycol homogeneous stirred in. 20 parts of an aqueous aluminum Effect pigment paste based on the aqueous polyurethane dispersion from DE A-42 24 617, preparation example 2 and the aqueous Polymer dispersion from DE-A-36 28 124, preparation example 1 in Solid weight ratio 1.2: 1 (pigment / binder Weight ratio 0.8: 1, solids content 29 wt .-%, Solvent content: 20% by weight butyl glycol and 5% by weight N- Methylpyrrolidone) and 2 parts of polypropylene glycol (hydroxyl number 280 mg KOH / g) added. Then with 24 parts of deionized water and 4 parts of n-butanol diluted. You get a silver one Effect water base paint.

The silver-colored is applied to the burned-in hydraulic filler layer Effect water basecoat in a vertical position in 10 µm Dry film thickness applied by compressed air spraying and after 5 Minutes flash off at 80 ° C with a commercially available two-component PU Clear varnish overcoated in a dry film thickness of 40 Fan and 20 Minutes baked at 140 ° C (object temperature).

The multi-layer coating obtained corresponds fully to the an automotive paint job.

The so produced with a multilayer paint structure according to the invention provided sheet was made with the measuring device sold by BYK-GARDNER "Wave scan" measured (cf. European Coatings Journal No. 1-2 (1995), Pages 32-35). The longwave value was 16.9 and for the short ripple of 13.6.

Example 5 (Comparative example, production of a silver-colored multi-layer effect coating according to the prior art)

Example 4 is repeated with the difference that instead of the white Hydraulic filler from Example 4 is a commercially available white hydraulic filler is used.

The multi-layer coating obtained corresponds fully to the an automotive paint job.

The one manufactured in this way with a typical car series effect paint system provided sheet was made with the measuring device sold by BYK-GARDNER "Wave Scan" measured. It gave a value for the long ripple of 30.8 and for the short ripple of 16.9.

Claims (8)

1. A process for the multi-layer coating of an electrically conductive substrate by electrophoretic application of a primer, baking the primer layer obtained, application of a hydraulic filler layer and a color and / or effect topcoat layer or basecoat film, the basecoat film being overcoated with a clearcoat film, characterized in that for the production a coating agent is used in the hydraulic filler layer, which contains:

• A) 50 to 85% by weight of one or more hybrid binders based on polyesters and (meth) acrylic copolymers with a hydroxyl number of 100 to 350 mg KOH / g and an acid number of 20 to 60 mg KOH / g,
• B) 0 to 20% by weight of one or more binders different from A),
• C) 15 to 50% by weight of one or more free or blocked polyisocyanates and / or one or more triazine-based components which crosslink with the hydroxyl groups of component A) to form ether and / or ester groups,

the sum of components A), B) and C) being 100% by weight Binder solid supplements, and wherein at least 50 wt .-% of (Meth) acrylic copolymers of component A) in the presence of at least 20% by weight of the polyester or components A) have been produced. 2. The method according to claim 1, characterized in that the  Hybrid binder A) from 30 to 95% by weight (Meth) acrylic copolymer and 5 to 70 wt .-% polyester exist. 3. The method according to claim 1 or 2, characterized in that the Hybrid binder A) has a hydroxyl number of 120 to 200 mg KOH / g exhibit. 4. The method according to claim 1, 2 or 3, characterized in that the hybrid binders A) have an acid number of 25 to 40 mg KOH / g exhibit. 5. The method according to any one of claims 1 to 4, characterized characterized in that the hybrid binders A) are available by radical polymerization of one or more esters unsaturated carboxylic acids with hydrophobic and hydrophilic Proportions in the presence of one or more hydroxy functional Polyester, the hydrophobic portions on monomeric esters based on unsaturated carboxylic acids with secondary OH groups, which can be present in a mixture with OH-free comonomers and the hydrophilic portions on unsaturated monomeric esters Carboxylic acids with primary OH groups, which are mixed with OH group-free comonomers can be present. 6. The method according to any one of the preceding claims, characterized characterized in that the hydraulic filler layer in a Dry film thickness of 25 to 50 microns is applied. 7. The method according to any one of the preceding claims, characterized characterized in that it is used for painting motor vehicles or whose parts are performed.