EP2038073A2

EP2038073A2 - Method for the production of colour- or effect-giving multilayer coatings

Info

Publication number: EP2038073A2
Application number: EP07785874A
Authority: EP
Inventors: Hubert Baumgart; Berthold Austrup; Michael Richert; Egon Wegner
Original assignee: BASF Coatings GmbH
Current assignee: BASF Coatings GmbH
Priority date: 2006-06-29
Filing date: 2007-06-29
Publication date: 2009-03-25
Also published as: WO2008000509A3; CN101479049B; CN101479049A; KR20090032103A; WO2008000509A2; JP2009541044A; DE102006030059A1; US20090324843A1

Abstract

The invention relates to a method for the production of colour- or effect-giving multilayer coatings, comprising a colour- or effect-giving base coat (A) and a transparent lacquer coat (B), by means of a wet-in-wet method using a colour- and/or effect-giving coating material (A) and a transparent coating material (B). The coating material (A) is produced from an aqueous structurally viscous free powder dispersion (A1), hardened by radical polymerisation and free of volatile organic components, comprising separately produced solid and/or highly viscous particles (A11) dimensionally stable under storage and application conditions as disperse phase with a particle size Z-mean of 80 to 759 nm as measured by photon correlation spectroscopy, a radically cross-linkable binder (A111) with a glass transition temperature of -70 to +500C, a fraction of olefinically unsaturated double bonds of 2 to10 equ./kg and a fraction of acid groups of 0.05 to 15 equ./kg in an amount of 50 to 100 wt. %, based on (A) and homogenising the above, the remaining components (A2) of the coating material (A) and homogenising the resulting mixture (A).

Description

Process for the preparation of colored and / or effect multicoat paint systems

Field of the invention

The present invention relates to a novel process for producing multicoat color and / or effect paint systems.

State of the art

A process for producing multicoat color and / or effect paint systems in which a color and / or effect basecoat material and a clearcoat material which can be cured by the free radical polymerization is known from German Patent Application DE 197 36 083 A1.

It is known that the free radical polymerization is carried out with compounds containing olefinically unsaturated double bonds. The radical polymerization can be initiated and maintained thermally or with actinic radiation.

Here and below actinic radiation electromagnetic radiation, such as near infrared (NIR), visible light, UV radiation, X-rays or gamma rays, in particular UV radiation, or corpuscular radiation, such as electron radiation, proton radiation, beta radiation, alpha radiation or neutron radiation, in particular electron radiation , Understood.

The known method provides condensation-resistant color and / or effect multi-layer coatings whose basecoats and clearcoats are adhesively bonded together.

The steadily growing demands of the market, in particular the increasing demands of automobile manufacturers and their customers on color and / or effect

However, multicoat paint systems force a continuous further development of the performance properties of the dyeing and / or effect-imparting

Multicoat paint systems, in particular with regard to the course, the gloss, the

Image distinctness, the stability of the color locus, the pigment orientation, in particular in the case of platelet-shaped effect pigments, adhesion to substrates, the

Intercoat adhesion, stone chip resistance, abrasion resistance,

Scratch resistance, weatherability, etch resistance, the

BESTATIGUNQSKOWE Chemical resistance, tree resin resistance, condensation resistance, bird dropping resistance and recoatability.

However, the growing demands also force a continuous development of the processes for the production of multicoat color and / or effect paint systems so that their performance properties can be specifically improved and optimally adapted to the requirements of the market. For this purpose, it is particularly necessary that the method varies widely and yet can be performed on existing coating equipment.

task

The object of the present invention is to provide a novel process for producing multicoat color and / or effect coatings comprising at least one color and / or effect basecoat (A) and at least one transparent topcoat (B), in which

(1) applying at least one color and / or effect coating material (A) to an uncoated or coated substrate,

(2) the resulting color and / or effect layer (A) ₁ without fully curing, dries,

(3) at least one transparent coating material (B) applied to the dried, color and / or effect layer (A) and

(4) at least the resulting transparent layer (B) together with the color and / or effect layer (A) hardens, resulting in the color and / or effect basecoat (A) and the transparent topcoat (B),

and that no longer has the disadvantages of the prior art, but varies widely with respect to the curing methods and yet can be carried out on existing equipment and provides color and / or effect multi-layer coatings, which in terms of history, gloss, the image distinguishability, stability the color location, the pigment orientation, in particular in the case of platelet-shaped effect pigments, the adhesion to substrates, the interlayer adhesion, the Rockfall resistance, abrasion resistance, scratch resistance, weather resistance, etch resistance, chemical resistance, tree resin resistance, condensation resistance, bird dropping resistance and recoatability, but in particular with regard to the course and the image distinguishability significantly improved.

solution

Accordingly, the new process for producing multicoat color and / or effect paint systems comprising at least one color and / or effect basecoat (A) and at least one transparent topcoat (B) was found, in which

(2) the resulting color and / or effect layer (A), without fully curing, dries,

wherein the color and / or effect coating material (A) or at least one of the color and / or effect coating materials (A) is prepared by

(5) at least one, by radical polymerization curable, pseudoplastic, completely or substantially free of volatile organic compounds powder dispersion (A1) containing as a disperse phase solid and / or highly viscous under storage and application conditions dimensionally stable particles (A1 1) a measured with the photon correlation spectroscopy mean particle size z-mean of 80 to 750 nm, containing at least one radically crosslinkable binder (A1 1 1) with a Glass transition temperature of -70 to +50 ⁰ C ₁ an olefinically unsaturated double bond content of 2 to 10 equ./kg and a content of acid groups from 0.05 to 15 equ./kg in an amount of, based on (A), 50 to 100% by weight, produced separately,

(6) they are mixed with the other constituents (A2) of the color and / or effect coating material (A) and

(7) homogenize the resulting mixture (A).

The new process for producing multicoat color and / or effect paint systems comprising at least one color and / or effect basecoat (A) and at least one transparent topcoat (B) is referred to below as "process according to the invention".

advantages

In view of the prior art, it was surprising and unforeseeable for the skilled person that the object on which the present invention was based could be achieved with the aid of the method according to the invention.

In particular, it was surprising that the process according to the invention no longer had the disadvantages of the prior art, but varied widely with respect to the curing methods and yet could be carried out on existing plants, yielding excellently reproducible results.

In addition, the process according to the invention provided multicoat color and / or effect coating systems which show the course, gloss, image distinctness, color point stability, pigment orientation, in particular for platelet effect pigments, adhesion to substrates, interlayer adhesion, chip resistance, abrasion resistance , improved scratch resistance, weatherability, etch resistance, chemical resistance, tree resin resistance, condensation resistance and bird drop resistance, but especially with regard to the course and the distinctiveness of the image significantly. Detailed description of the invention

The process according to the invention is used to produce multicoat color and / or effect paint systems comprising at least one basecoat (A) having a color and / or effect and at least one topcoat (B). In addition, they may contain at least one further customary and known coating, such as single-coat or multi-coat primer coatings, electrodeposition coatings, anticorrosive coatings,

Stone impact protection primers and / or surfacer coatings, but in particular

Electrocoating and antistonechip primers or surfacer coatings.

The color and / or effect basecoats (A) are used for coloring and / or the adjustment of physical and / or chemical effects, eg. Optical effects such as metallic effects, interference effects, flop effects or fluorescence, corrosion protection, electrical conductivity and magnetic shielding; In particular, however, they serve to color and / or adjust metallic effects, interference effects and flop effects.

The transparent topcoats (B) can be clear and glossy or frosted. They can be tinted or colorless. Preferably, they are colorless, clear and glossy clearcoats (B).

The multicoat color and / or effect paint systems produced by the process according to the invention can be present on a wide variety of substrates.

Preferably, the substrates of metals, plastics, wood, ceramics, stone, textile, fiber composites, leather, glass, glass fibers, glass and rock wool, mineral and resin-bound building materials, such as gypsum and cement boards or roof tiles, and composites of these materials.

Preferably, the substrates are um

land, sea or air powered means of muscle, hot air or wind such as bicycles, trolleys, rowing boats, sailboats, hot air balloons, gas balloons or gliders, and parts thereof motorized means of transport by land, sea or air, such as motorcycles, utility vehicles or motor vehicles, in particular cars, over or underwater vessels or aircraft, and parts thereof, stationary floats, such as buoys or parts of docks - indoor and outdoor structures , Doors, windows and furniture and glass hollow bodies, industrial small parts, such as screws, nuts, hubcaps or rims, containers, such as coils, containers or packaging, - electrical components, such as coils, optical components, mechanical components and white goods, such as household appliances, boilers and radiators.

In particular, the substrates are car bodies and parts thereof.

The inventive method is a so-called wet-on-wet method, in which one

(2) the resulting color and / or effect layer (A), without fully curing, dries,

(4) at least the resulting transparent layer (B) together with the color and / or effect layer (A) hardens, whereby the color and / or effect basecoat (A) and the transparent topcoat (B) result.

In the process step (4), if appropriate, previously applied layers such as electrodeposition coating layers or surfacer layers can also be cured. Methods of this type are known (cf., for example, German Patent Application DE 100 27 292 A1, page 13, paragraph [0109], to page 14, paragraph [0118]).

Preferably, the usual and known spray application methods are used in these methods.

For the process of the invention, it is essential that the color and / or effect coating material (A) or at least one of the color and / or effect coating materials (A) is prepared by

(5) at least one, in particular one, by radical polymerization curable, aqueous, pseudoplastic completely or substantially free of volatile organic compounds powder dispersion (A1) containing as the disperse phase solid and / or highly viscous under storage and application conditions dimensionally stable particles (A1 1) with a measured by photon correlation spectroscopy average particle size z-mean 80-750 nm, containing at least one free-radically crosslinkable binder (A1 1 1) having a glass transition temperature of -70 to +50 ⁰ C, a content of olefinically unsaturated double bonds of 2 to 10 equ./kg and a content of acid groups from 0.05 to 15 equ./kg in an amount of, based on (A), 50 to

100% by weight, produced separately,

(7) homogenize the resulting mixture (A).

The powder dispersion (A1) is completely or substantially free of organic solvents.

"Substantially free" means that the relevant powder dispersion (A1) has a solvent content of <10% by weight, preferably in each case <5% by weight and in particular <2% by weight).

"Completely free from" means that the solvent content is below the usual and known detection limits for organic solvents. The powder dispersion (A1) is pseudoplastic.

The viscosity behavior, referred to as "pseudoplastic," describes a state which, on the one hand, takes into account the requirements of storage and settling stability of the powder dispersion (A1) as such: in the agitated state, for example when pumping the powder dispersion (A1 ) in the ring line of a coating system and during application, the powder dispersion (A1) as such assumes a low-viscosity state, which ensures good processability. Without shear, however, the viscosity increases. The higher viscosity in the still state, such as in storage, tends to prevent settling of the solid particles (A11) of the powder dispersion (A1) or re-agitation of the powder dispersion (A1 ) is guaranteed.

The pseudoplastic behavior is preferably adjusted by means of suitable thickeners (A112), in particular nonionic and ionic thickeners (A112), which are preferably present in the aqueous phase (A12) of the powder dispersion (A1).

For the pseudoplastic behavior, preference is given to setting a viscosity range of 50 to 1,500 mPas at a shear rate of 1,000 s ^-1 and from 150 to 8,000 mPas at a shear rate of 10 s ^-1 and from 180 to 12,000 mPas at a shear rate of 1 s ^-1 ,

The powder dispersion (A1) contains as disperse phase solid and / or highly viscous, dimensionally stable particles (A11).

"Dimensionally stable" means that under the usual and known conditions of storage and application of pseudoplastic aqueous powder dispersions, the particles (A11) only slightly agglomerate, if at all, and / or disintegrate into smaller particles, but also under the influence of shear forces preserve the original form completely or substantially.

The particles (A1 1) have an average particle size z-mean of 80 to 750 nm, preferably 80 to 600 nm and in particular 80 to 400 nm, measured by photon correlation spectroscopy. Photon correlation spectroscopy is a common and known method for measuring dispersed particles with particle sizes <1 μm. For example, the measurement can be performed using the Malvern® Zetasizer 1000.

The particle size distribution can be adjusted in any way. The particle size distribution preferably results from the use of suitable wetting agents (A112).

The content of the powder dispersion (A1) of particles (A11) can vary very widely and depends on the requirements of the individual case.

Preferably, the content is 5 to 70, preferably 10 to 60, particularly preferably 15 to 50 and in particular 15 to 40 wt .-%, based on the powder dispersion (A1).

The particles (A11) contain at least one, in particular one, radically crosslinkable binder (A111)

a glass transition temperature of -70 to +50 ⁰ C, preferably -60 to + 20 ⁰ C and in particular -60 to +10 ⁰ C,

a content of olefinically unsaturated double bonds of 2 to 10 equ./kg, preferably 2 to 8 equ./kg, preferably 2.1 to 6 equ./kg, more preferably 2.2 to 6 equ./kg, most preferably 2.3 to 5 equ./kg and in particular 2.5 to 5 equ./kg of the binder (A111) and

a content of acid groups of 0.05 to 15 equ./kg, preferably 0.08 to 10 equ./kg, preferably 0.1 to 8 equ./kg, more preferably 0.15 to 5 equ./kg, completely particularly preferably 0.18 to 3 equ./kg and in particular 0.2 to 2 equ./kg of the binder (A111).

The content of acid groups is preferably determined by the acid number according to DIN EN ISO 3682.

The particles (A11) contain the binders (A111) in an amount of 50 to 100% by weight, preferably 55 to 100% by weight, preferably 60 to 99% by weight, particularly preferably 70 to 99% by weight. and in particular 80 to 99 wt .-%, each based on (A1 1). Thus, the particles (A11) may consist of the binder (A111). The particles (A11) preferably also contain at least one of the additives (A112) described below.

Preferably, the olefinically unsaturated double bonds of the binder (A111) are in groups selected from the group consisting of (meth) acrylate, ethacrylate, crotonate, cinnamate, vinyl ether, vinyl ester, dicyclopentadienyl, norbornyl, isoprenyl , Isopropenyl, allyl or butenyl groups; Dicyclopentadienyl, norbomenyl, isoprenyl, isopropenyl, allyl or butenyl ether groups or dicyclopentadienyl, norbornyl, isoprenyl, isopropenyl, allyl or butenyl ester groups, preferably (meth) acrylate groups. In particular, the olefinically unsaturated double bonds are present in acrylate groups.

The binders (A111) are oligomeric or polymeric.

"Oligomer" means that the relevant binder (A111) is composed of 3 to 12 monomeric structural units. The structural units may be the same or different.

"Polymer" means that the relevant binder (A11 1) is composed of more than 8 monomeric structural units. Again, the structural units may be the same or different.

Whether a binder (A111) composed of 8 to 12 monomeric units is considered to be an oligomer or a polymer depends primarily on its number average molecular weight.

The number average molecular weight of the binder (A111) can vary widely and depends on the requirements of the individual case, in particular the viscosity, which is advantageous for the processing and the use of the binder (A111). Thus, the viscosity of the binder (A111) is usually adjusted so that after the application of the powder dispersion (A1) as such and the drying of the resulting wet layer, a problem-free and easy filming of the particles (A11) is achieved.

The number-average molecular weight is preferably from 1000 to 50,000 daltons, preferably from 1,500 to 40,000 daltons and in particular from 2,000 to 20,000. The nonuniformity of the molecular weight may likewise vary widely and is preferably from 1 to 10, in particular from 1.5 to 8.

Suitable binders (A1 1 1) are all oligomers and polymers which have the property profile described above.

Preferably, the binder (A1 1 1) is selected from the group consisting of oligomeric and polymeric epoxy (meth) acrylates, urethane (meth) acrylates and carbonate (meth) acrylates. In particular, urethane (meth) acrylates are used.

The urethane (meth) acrylates (A1 11) are preferably preparable by reaction of

(a1) at least one compound containing at least two isocyanate groups, selected from the group consisting of aliphatic, aromatic or cycloaliphatic di- and polyisocyanates, with

(a2) at least one compound having at least one, in particular one, isocyanate-reactive functional group, preferably selected from the group consisting of hydroxyl groups, thiol groups and primary and secondary

Amino groups, in particular hydroxyl groups, and at least one, in particular one, of the groups described above which contain a free-radically polymerizable, olefinically unsaturated double bond, preferably a (meth) acrylate group, in particular an acrylate group,

(a3) at least one compound having at least one, in particular one, isocyanate-reactive functional group and at least one, in particular one, acid group, preferably selected from the group consisting of carboxylic, phosphonic, phosphinic, sulfonic, and sulfinic, preferably carboxylic acid - And sulfonic acid groups, in particular carboxylic acid groups, and

(a4) if appropriate, at least one compound having at least two, in particular two, isocyanate-reactive functional groups. Examples of suitable compounds (a1) are customary and known di- and polyisocyanates having an isocyanate functionality of on average 2 to 6, preferably 2 to 5 and in particular 2 to 4.

"Aliphatic" means that the isocyanate group in question is linked to an aliphatic carbon atom.

"Cycloaliphatic" means that the isocyanate group in question is linked to a cycloaliphatic carbon atom.

"Aromatic" means that the isocyanate group in question is linked to an aromatic carbon atom.

Examples of suitable aliphatic diisocyanates (a1) are aliphatic diisocyanates, such as tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate,

Octamethylene diisocyanate, decamethylene diisocyanate, dodecamethylene diisocyanate, tetradecamethylene diisocyanate, derivatives of lysine diisocyanate,

Tetramethylxylylidenediisocyanat, trimethylhexane diisocyanate or 1, 3- or 1, 4-bis (isocyanatomethyl) cyclohexane.

Examples of suitable cycloaliphatic diisocyanates (a1) are 1, 4-, 1, 3- or 1, 2-diisocyanatocyclohexane, Tetramethylcyclohexandiisocyanat, bis (4'-isocyanatocyclohexyl) methane, (4 -lsocyanatocyclohexyl ¹⁾ - (2'-isocyanatocyclohexyl) methane, 2,2-bis (isocyanatocyclohexyl) propane, 2,2- (4'-isocyanatocyclohexyl) - (2'-isocyanatocyclohexyl) propane, 1-isocyanato-3,3,5-trimethyl-5- (isocyanatomethyl) cyclohexane (isophorone diisocyanate) , 2,4- or 2,6-diisocyanato-1-methylcyclohexane or diisocyanates derived from dimer fatty acids, as sold under the trade name DDI 1410 by the company Henkel and described in the patents WO 97/49745 and WO 97/49747, such as 2-heptyl-3,4-bis (9-isocyanatononyl) -1-pentylcyclohexane.

Examples of suitable aromatic diisocyanates (a1) are 2,4- or 2,6-tolylene diisocyanate or their mixtures of isomers, m- or p-xylylene diisocyanate, 2,4'- or 4,4'-diisocyanatodiphenylmethane or their isomer mixtures, 1,3-or 1, 4-phenylene diisocyanate, 1-chloro-2,4-phenylene diisocyanate, 1, 5-naphthylene diisocyanate, diphenyl-4,4'-diisocyanate, 4,4'-diisocyanato-3,3'-dimethyldiphenyl, 3-methyl-diphenylmethane 4,4'-diisocyanate, 1, 4-diisocyanatobenzene or 4,4'-diisocyanato-diphenyl ether. Preferably, aliphatic and cycloaliphatic diisocyanates (a1), especially hexamethylene diisocyanate, 1, 3-bis (isocyanatomethyl) cyclohexane, isophorone diisocyanate and / or di (isocyanatocyclohexyl) methane used.

Examples of suitable polyisocyanates (a1) are triisocyanates such as nonantocyanate (NTI) and polyisocyanates (a1) based on the above-described diisocyanates and triisocyanates (a1), in particular oligomers containing isocyanurate, biuret, allophanate, iminooxadiazinedione, urethane , Carbodiimide, urea, uretonimine and / or uretdione groups. Examples of suitable polyisocyanates (a1) of this type and processes for their preparation are described, for example, in patents and patent applications CA 2,163,591 A 1, US Pat. No. 4,419,513 A, US Pat. No. 4,454,317 A, EP 0 646 608 A1, US Pat. No. 4,801,675 A, EP 0 183 976 A 1, DE 40 15 155 A1, EP 0 303 150 A1, EP 0 496 208 A1, EP 0 524 500 A1, EP 0 566 037 A1, US Pat. No. 5,258,482 A, US Pat. No. 5,290,902 A, EP 0 649 806 A 1, DE 42 29 183 A 1 or EP 0 531 820 A 1 known.

Preferably, the oligomers (a1) of hexamethylene diisocyanate and isophorone diisocyanate are used.

Examples of suitable compounds (a2) are the monoesters of

(a21) Diols and polyols which preferably contain 2 to 20 carbon atoms and at least 2 hydroxyl groups in the molecule, such as ethylene glycol, diethylene glycol, triethylene glycol, 1, 2-propylene glycol, 1, 3-propylene glycol, 1, 1-dimethyl-1, 2 ethanediol, dipropylene glycol, tripropylene glycol, tetraethylene glycol,

Pentaethylene glycol, 1,4-butanediol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, 2-methyl-1,5-pentanediol, 2-ethyl-1,4-butanediol, 1,4-dimethylolcyclohexane, 2, 2-bis (4-hydroxycyclohexyl) propane, glycerol, trimethylolethane, trimethylolpropane, pentaerythritol, dipentaerythritol, ditrimethylolpropane, erythritol, sorbitol, polytetrahydrofuran having an average molecular weight of from 162 to 2,000, polyisocyanate

1, 3-propanediol having an average molecular weight of 134 to 400 or polyethylene glycol having a molecular weight between 150 and 500, in particular ethylene glycol; With

(a22) alpha, beta-unsaturated carboxylic acids, such as acrylic acid, methacrylic acid, crotonic acid, itaconic acid, fumaric acid, maleic acid, acrylalmidoglycolic acid, methacrylamidoglycolic acid, especially acrylic acid. Further examples of suitable compounds (a2) are the monovinyl ethers of the above-described diols and polyols (a21).

Further examples of suitable compounds (a2) are the monoesters or monoamides of the above-described alpha, beta-unsaturated carboxylic acids (a22) with

(a23) amino alcohols, such as 2-aminoethanol, 2- (methylamino) ethanol, 3-amino-1-propanol, 1-amino-2-propanol or 2- (2-aminoethoxy) ethanol,

(a24) thioalcohols, such as 2-mercaptoethanol, or

(a25) polyamines, such as ethylenediamine or diethylenetriamine.

In particular, 2-hydroxyethyl acrylate is used.

Examples of suitable compounds (a3) are

(a31) hydroxycarboxylic acids, such as hydroxyacetic acid (glycolic acid), 2- or 3-hydroxypropionic acid, 3- or 4-hydroxybutyric acid, hydroxypivalic acid, 6-

Hydroxycaproic acid, citric acid, malic acid, tartaric acid, 2,3-dihydroxypropionic acid (glyceric acid), dimethylolpropionic acid,

Dimethylol butyric acid, trimethylolacetic acid, salicylic acid, 3- or 4-hydroxybenzoic acid or 2-, 3- or 4-hydroxycinnamic acid,

(a32) amino acids such as 6-aminocaproic acid, aminoacetic acid (glycine), 2-aminopropionic acid (alanine), 3-aminopropionic acid (beta-alanine) or the other essential amino acids; N, N-bis (2-hydroxyethyl) glycine, N- [bis (hydroxymethyl) methyl] glycine or imidodiacetic acid,

(a33) sugar acids, such as gluconic acid, glucaric acid, glucuronic acid, galacturonic acid or mucic acid (galactaric acid),

(a34) thiolcarboxylic acids, such as mercaptoacetic acid, or

(a35) sulfonic acids, such as 2-aminoethanesulfonic acid (taurine), aminomethanesulfonic acid, 3-aminopropanesulfonic acid, 2- [4- (2-hydroxyethyl) -1-piperazinyl] -ethanesulfonic acid, 3- [4- (2-hydroxyethyl) -piperazinyl] -propanesulfonic acid, N- [tris (hydroxymethyl) -methyl] -2-aminoethanesulfonic acid, N , N-bis (2-hydroxyethyl) -2-aminoethanesulfonic acid, 5-sulfosalicylic acid, 8-hydroxyquinoline-5-sulfonic acid, phenol-4-sulfonic acid or sulfanilic acid.

In particular, hydroxyacetic acid (glycolic acid) (a31) is used.

The acid groups can be ionized.

Examples of suitable counterions are lithium, sodium, potassium, rubidium, cesium, magnesium, strontium, barium or ammonium ions and primary, secondary, tertiary or quaternary ammonium ions, which are derived from customary and known organic amines.

Examples of suitable compounds (a4) are the above-described compounds diols and polyols (a21), amino alcohols (a23), thioalcohols (a24) or polyamines (a25).

Preferably, for the preparation of the urethane (meth) acrylates (A11 1), the compounds (a1), (a2) and (a3) and optionally (a4) are reacted in a molar ratio with each other to 3 equ. Isocyanate groups from the compound (a1)

0.5 to 3, preferably 0.8 to 2.5, particularly preferably 1, 0 to 2.2 and in particular 1, 4 to 1, 8 equ. isocyanate-reactive functional groups from the compound (a2) and

0.001 to 1, 5, preferably 0.005 to 1, 0, particularly preferably 0.01 to 0.8 and in particular 0.1 to 0.5 equ. isocyanate-reactive functional groups from the compound (a3) and optionally

- 0 to 2, preferably 0.1 to 1, 8, more preferably 0.5 to 1, 5 and in particular 0.8 to 1, 3 equ. isocyanate-reactive functional groups from the compound (a4)

come.

However, it is also possible to use urethane (meth) acrylates (A111) which comprise at least one reaction product having an epoxide group content (calculated as M = 42 daltons) <0.2% by weight and an acid number <10, preferably <6 and in particular <4 mg KOH / g, can be prepared from at least one olefinically unsaturated carboxylic acid and at least one glycidyl ester of an unsaturated carboxylic acid, and at least one polyisocyanate are prepared.

An example of a particularly suitable reaction product is the reaction product of acrylic acid with glycidyl methacrylate. Very particularly suitable reaction products of this type, in each case based on their respective total amount, at least 60, preferably at least 70 and in particular at least 80 wt .-% of a mixture of 3-acryloyloxy-2-hydroxy-propyl methacrylate and 2-acryloyloxy-3-hydroxy - propyl methacrylate.

The urethane (meth) acrylates (A111) and the processes for their preparation are described in detail in the German patent application DE 103 57 712 A1, page 3, paragraph [0008], page 3, paragraph [0011], to page 5, paragraph [ 0022], as well as page 9, examples, paragraph [0050], to page 13, paragraph [0061], page 14, paragraph [0067], and page 15, paragraph [0070], to page 16, paragraph [0075] ,

From a methodological point of view, the preparation of the urethane (meth) acrylates (A1 11) has no special features, but takes place under the customary and known conditions of the reaction of polyisocyanates with the exclusion of water at temperatures of 5 to 100 ^° C. To initiate polymerization of the olefinic To inhibit unsaturated double bonds, is preferably carried out under an oxygen-containing gas, in particular under air or air-nitrogen mixtures.

The powder dispersion (A1) consists of at least one disperse phase (A11) and a continuous aqueous phase (A12). In the simplest case, the disperse phase (A11) consists of the binder (A111) and the continuous phase (A12) of water. Preferably, however, the powder dispersion (A1) also contains at least one customary and known additive (A112) in customary and known amounts.

Depending on its physicochemical properties, an additive (A112) may be present in the disperse phase (A11), ie the dimensionally stable particles (A11); but it may also form a separate disperse phase (A13), such as a pigment. In addition, it may be exclusively in the aqueous phase (A12), such as a water-soluble salt, or may accumulate in the interface between aqueous phase (A12) and disperse phase (A11), such as a wetting agent. Last but not least, the additive (A112) between the disperse phase (A11) and the aqueous phase (A12), such as a molecularly dispersed organic dye. The person skilled in the art can therefore easily predict how an additive (A112) will behave in the powder dispersion (A1).

Preferably, the additive (A112) from the group consisting of residue-free or substantially residue-free thermally decomposable salts; different binders physically, thermally and / or with actinic radiation from the binders (A111); thermally curable crosslinkers; Neutralizing agents; thermally curable reactive diluents; curable with actinic radiation reactive diluents; opaque and transparent, color and / or effect pigments, in particular organic and inorganic metallic effect pigments, interference pigments, fluorescent pigments, electrically conductive pigments, magnetically shielding pigments and corrosion-inhibiting pigments; molecularly soluble dyes; opaque and transparent, organic and inorganic fillers; organic and inorganic nanoparticles; Light stabilizers; antioxidants; Venting means; Wetting agents; emulsifiers; slip additives; polymerization inhibitors; Initiators of radical polymerization, especially photoinitiators; thermolabile radical initiators; Adhesion promoters; Leveling agents; film-forming aids; Rheology auxiliaries, such as thickeners and pseudoplastic Sag control agents, SCA; Flame retardants; Corrosion inhibitors; anti-caking agents; To grow; driers; Biocides and matting agents; selected.

Preferably, the powder dispersion (A1) contains residue-free or substantially residue-free thermally decomposable salts, light stabilizers, wetting agents, emulsifiers, leveling agents, photoinitiators or thermolabile free-radical initiators and rheological aids as additives (A112).

Examples of suitable additives (A112) are from the German patent applications

DE 101 26 649 A1, page 16, paragraph [0145], to page 18, paragraph [0189],

DE 100 27 270 A1, page 11, paragraphs [0106] and [0107] or

DE 101 35 997 A1, page 3 [0022] to page 4, paragraph [0033], and page 4, paragraphs [0039] and [0040], page 10, paragraphs [0092] to [0101], known.

Contains the powder dispersion (A1) thermally curable components (A112), they are in the dimensionally stable particles (A11) preferably in an amount <40 wt .-%, preferably <30 wt .-% and in particular <20 wt .-%.

The powder dispersion (A1) is preferably prepared by the secondary dispersion method known from German Patent Application DE 199 08 013 A1, German Patent DE 198 41 842 C2 or German Patent Application DE 100 55 464 A1.

In this process, the binders (A11 1) and optionally the additives (A112) are dissolved in organic solvents, in particular readily volatile, water-miscible solvents. The resulting solutions are dispersed in water (A12) using neutralizing agents (A112). It is then diluted with water (A12) with stirring. It initially forms a water-in-oil emulsion, which turns on further dilution in an oil-in-water emulsion. This point is generally reached at solids contents of <50% by weight, based on the emulsion, and is externally evident from a greater decrease in viscosity during dilution.

The oil-in-water emulsion can also be prepared directly by the melt emulsification of the binders (A111) and optionally the additives (A112) in water (A12).

It is advantageous if the wetting agents (A112) are added to the organic solution and / or the water (A12) before or during the emulsification. Preferably, they are added to the organic solution.

The solvent-containing emulsion thus obtained is subsequently freed of solvents by azeotropic distillation.

According to the invention, it is advantageous if the solvents to be removed are distilled off at a distillation temperature below 70 ^° C., preferably below 50 ^° C. and in particular below 40 ^° C. Optionally, the distillation pressure is chosen so that this temperature range is maintained at higher boiling solvents.

In the simplest case, the azeotropic distillation can be accomplished by stirring the emulsion at room temperature in an open vessel for several days. In the In the preferred case, the solvent-containing emulsion is freed from the solvents by vacuum distillation.

The evaporated or distilled off amount of water and solvents are replaced by water (A12) to avoid high viscosities. The addition of the water (A12) can be carried out before, after or even during the evaporation or the distillation by adding in portions.

After loss of the solvents, the glass transition temperature of the dispersed dimensionally stable particles (A11) increases, and instead of the previous solvent-containing emulsion, the pseudoplastic aqueous powder dispersion (A1) is formed.

Optionally, the dimensionally stable particles (A11) are mechanically comminuted in the wet state, which is also referred to as wet milling. Preferably conditions 60 and in particular 5O ⁰ C in this case be applied so that the temperature of the ground material 70 preferably does not exceed. The specific energy input during the milling process is preferably 10 to 1000, preferably 15 to 750 and in particular 20 to 500 Wh / g.

For wet grinding, a wide variety of devices can be used which produce high or low shear fields.

Examples of suitable devices which produce low shear fields are customary and known stirred tanks, gap homogenizers, microfluidizers or dissolvers.

Examples of suitable devices which produce high shear fields are conventional and known stirred mills or inline dissolvers.

Most preferably, the devices that produce high shear fields are used. Of these, the agitator mills according to the invention are particularly advantageous and are therefore used with very particular preference.

In general, in the case of wet grinding, the powder dispersion (A1) is fed to the devices described above with the aid of suitable devices, such as pumps, in particular gear pumps, and circulated until the desired particle size has been reached. Preferably, the powder dispersion (A1) is filtered before use. For this purpose, the usual and known filtration devices and filters are used. The mesh size of the filters can vary widely and depends primarily on the particle size and the particle size distribution of the particles. The person skilled in the art can therefore easily determine the suitable filters on the basis of this physical parameter. Examples of suitable filters are monofilament surface filters or bag filters. These are available on the market under the brands Pong® or Cuno®.

The above-described powder dispersion (A1) is mixed in the process according to the invention in process step (6) with the other constituents (A2) of the color and / or effect coating material (A), after which the resulting mixture (A) in process step (7). is homogenized.

In this case, the amount of powder dispersion (A1) used in the process according to the invention can vary widely and can thus be excellently adapted to the requirements of the individual case. So much powder dispersion (A1) is preferably used that the color and / or effect coating material (A), based on its total amount, 1 to 20 wt .-%, preferably 2 to 17.5 wt .-% and in particular 5 to 15 wt .-% of the binder (A111).

Examples of suitable constituents (A2) which can be used to advantage for the preparation of the color and / or effect coating material (A) are from international patent application WO 92/15405, page 2, line 35, to page 12, line 14 , the German patent applications

DE 44 37 535 A1, page 2, line 24, to page 6, line 59,

DE 199 14 98 A1, column 4, line 23, to column 15, line 63,

DE 199 48 004 A1, page 3, line 14, to page 17, line 5, and

German Patent DE 100 43 405 C1, column 5, paragraphs [0030] to [0033] and column 9, paragraph [0062] to column 11, paragraph [0070]. Preferably, they are used in the usual and known effective amounts. The color and / or effect layer (A) resulting in process step (1) is dried in process step (2) without completely curing it.

The drying may be accelerated by the use of a gaseous, liquid and / or solid hot medium such as hot air, heated oil or heated rolls, or microwave, infrared and / or near infrared (NIR) light. Preferably, the wet layer is dried in a circulating air oven at 23 to 150 ⁰ C, preferably 30 to 120 ⁰ C and in particular 50 to 100 ° C dried.

According to the invention, it is advantageous to irradiate the color and / or effect layer (A) before the process step (3) with actinic radiation, in particular UV radiation. In this case, the customary and known methods and devices described below can be used. During irradiation, a dose can be used which is sufficient for the complete free-radical polymerization of the free-radically polymerizable, olefinically unsaturated double bonds present. However, a dose is preferably used in which not all free-radically polymerizable, olefinically unsaturated double bonds radically polymerize.

Preferably, the color and / or effect coating material (A) is applied in process step (1) in a wet layer thickness, that after complete curing of the color and / or effect layer (A) in process step (4) has a layer thickness of 5 to 25 μm, preferably 5 to 20 μm and in particular 5 to 15 μm results.

In process step (3), the color and / or effect layer (A) is coated with at least one transparent coating material (B).

The transparent coating material (B) may have a composition such that after complete curing of the transparent layer (B) in process step (4), a transparent topcoat (B) results which is clear, glossy, frosted, tinted or colorless. The transparent topcoat (B) is preferably a colorless, clear and glossy clearcoat.

The transparent coating materials (B) are therefore preferably the customary and known, thermal, with actinic radiation or thermally and with actinic

Radiation (dual-cure) curable clearcoats used. Examples of suitable clearcoats are from German patent DE 100 43 405 C1, column 8, paragraph [0054], or German patent application DE 199 48 004 A1, page 18, lines 7 to 30, known.

The transparent coating materials (B) are applied in process step (3) in a wet layer thickness, that after complete curing in process step (4) results in a layer thickness of preferably 10 to 100 .mu.m, preferably 20 to 80 .mu.m and in particular 25 to 70 microns.

In process step (4), at least the above-described layers (A) and (B) are cured together.

It is a great advantage of the process according to the invention that the curing can be carried out not only by dual-cure curing but, if necessary, purely thermally. This is of particular importance, even if the shadow zones of three-dimensionally complex shaped substrates such as car bodies are to be fully cured.

From a methodological point of view, the thermal curing has no special features, but can be carried out with the aid of the devices and methods described above.

Methodically, the curing with actinic radiation has no special features, but can by means of conventional and known devices and methods, as described for example in German Patent Application DE 198 18 735 A 1, column 10, lines 31 to 61, the German Patent application DE 102 02 565 A1, page 9, paragraph [0092], to page 10, paragraph [0106], German patent application DE 103 16 890 A1, page 17, paragraphs [0128] to [0130], in the international patent application WO 94/11123, page 2, lines 35, to page 3, line 6, page 3, lines 10 to 15, and page 8, lines 1 to 14, or the American patent US 6,743,466 B2, column 6, line 53, to column 7, line 14, are performed.

The color and / or effect multicoat paint systems produced in accordance with the method of the invention fulfill all the requirements which are imposed on automotive finishes (see European Patent EP 0 352 298 B1, page 15, lines 42, to page 17, line 40) and correspond to Appearance of a Class A surface in full. Examples and Comparative Experiments

Production Example 1

Preparation of UV Radiation Initiated Radical Polymerization Curable Powder Dispersion (A1-1)

For the preparation of the powder dispersion (A1-1), the binder (A111-1) was first prepared in the following manner.

Isopropenylidenedicyclohexanol was coarsely dispersed in hydroxyethyl acrylate at 6O ⁰ C with stirring. To this suspension were added the polyisocyanates, pentaerythritol tri / tetra-acrylate, hydroquinone monomethyl ether, 1,6-di-tert-butyl-p-cresol and methyl ethyl ketone. Upon addition of dibutyltin dilaurate, the reaction mixture warmed. The mixture was stirred at 75 ° C for several hours until the content of free isocyanate groups was constant. Then glycolic acid and methanol were added and stirred until no more free isocyanate groups were detectable.

The hydroxyl-containing compounds and the polyisocyanates were used in amounts that gave the following equivalent ratios:

Isopropenylidenedicyclohexanol 33.7 equ. OH

2-hydroxyethyl acrylate 24.7 equ. OH

Pentaerythritol tri / tetra-acrylate (average OH number:

100 to 111 mg KOH / g) 24.7 equ. OH

Basonat® HI 100 from BASF AG 56.25 equ. NCO

Allophanate from hexamethylene diisocyanate and

2-hydroxyethyl acrylate according to international

Patent application WO 00/39183 18.75 equ. NCO

Desmodur® W from Bayer Aktiengesellschaft 25 equ. NCO Hydroquinone monomethyl ether 0.05 wt .-%, based on the solids

1, 6-di-tert-butyl-p-cresol 0.1 wt .-%, based on the solids

Methyl ethyl ketone corresponding to a solids content of 70 wt .-% in

Dibutyltin dilaurate 0.02 wt .-%, based on the solids

Glycolic acid 6.8 equ. OH

Methanol 10.1 equ. OH

The urethane (meth) acrylate (A111-1) had a solids content of 70 wt .-%, a glass transition temperature of 2.5 ° C, a content of olefinically unsaturated double bonds of 2.93 equ./kg and an acid number of 18, 85 mg KOH / g.

In addition, the urethane (meth) acrylate (A111-2) was prepared as described above, except that Desmodur® W was replaced by the equivalent amount of allophanate of hexamethylene diisocyanate and 2-hydroxyethyl acrylate according to International Patent Application WO 00/39183. The urethane (meth) acrylate (A111-2) had a solids content of 71 wt .-%, a glass transition temperature of 12.3 ° C, a content of olefinically unsaturated double bonds of 3 equ./kg and an acid number of 15.8 mg KOH / g on.

The powder dispersion (A1-1) was prepared by the secondary dispersion method by mixing the following ingredients in the order listed, distilling off the organic solvents, replacing the removed organic solvents by water and homogenizing the resulting mixture:

751, 123 parts by weight of urethane (meth) acrylate (A111-1), 493.696 parts by weight of urethane (meth) acrylate (A111-2), 26.289 parts by weight of methyl ethyl ketone, 12.137 parts by weight of Lutensol® AT 50 (commercial wetting agent from BASF Aktiengesellschaft), 20.861 parts by weight of triethylamine, a total of 35.052 parts by weight of Irgacure® 184 (commercial photoinitiator from Ciba Specialty Chemicals) and Lucirin® TPO (commercial photoinitiator from BASF Aktiengesellschaft) in a weight ratio of 5 : 1, 1,660,842 parts by weight of deionized water,

24 parts by weight Acrysol® RM-8W (commercial associative thickener from Rohm and Haas) and - 24 parts by weight deionized water.

Production Example 2

Preparation of Thermally Initiated Radical Polymerization Curable Powder Dispersion (A1-2)

The powder dispersion (A1-2) was prepared by the secondary dispersion method by mixing the following ingredients in the order listed, distilling off the organic solvents, replacing the removed organic solvents by water and homogenizing the resulting mixture:

755.198 parts by weight of urethane (meth) acrylate (A111-1),

496.374 parts by weight of urethane (meth) acrylate (A111 -2),

52.864 parts by weight of methyl ethyl ketone, 12.203 parts by weight of Lutensol® AT 50 (commercial wetting agent from BASF

Aktiengesellschaft)

20.974 parts by weight of triethylamine,

13.745 parts by weight of initiator BK (oligomeric benzpinacol silyl ether in

Triethyl phosphate / toluene from Bayer Distribution Service GmbH), 13.216 parts by weight of the commercial Byk® N leveling additive from Byk

Chemistry,

1,635.428 parts by weight deionized water,

24 parts by weight of Acrysol® RM-8W (commercial associative thickener of the company

Rohm and Haas) and - 24 parts by weight of deionized water. Production Example 3

The preparation of the thermally initiated free-radical polymerization curable powder dispersion (A1-3)

For the preparation of the powder dispersion (A1-3), the urethane (meth) acrylate (A111-3) was first prepared according to the following procedure.

9,290 g of glycidyl methacrylate, 70 g of triphenylphosphine and 14 g of 2,6-di-tert-butyl-4-methylphenol were placed in a suitable stirred tank. 5 l / h of air were passed through and 101 / h over the mixture. The mixture was heated to 70 ^° C. with stirring. At this temperature, 4.710 g of acrylic acid were added within five hours. The

Temperature rose to 81 ° C at the beginning. After the subsidence exothermic was the

Reaction mixture kept at 65 to 70 ⁰ C. After the end of the addition, the temperature was raised to 90 ⁰ C. After six hours at 90 ^° C., an acid number of 9.4 mg KOH / g was measured on a sample taken. Subsequently, another 14 g of triphenylphosphine were added. After a further six hours at 90 ^° C., an acid number of 1.8 mg KOH / g was measured on a sample taken. The

The reaction mixture was stirred for a further 24 hours at 90 ° C and then their epoxide content was determined. It was 0.1% by weight.

In one suitable for the reaction of polyisocyanates reaction vessel having a stirrer and gas inlet tube, h air 1724.22 g of a polyisocyanate based on hexamethylene diisocyanate (Desmodur® XP 2410 from Bayer AG) were introduced at 0.3 l / ₁ 1,155 g of butyl acetate , 4.09 g of 2,6-di-tert-butyl-4-methylphenol and 2.04 g of a tin-containing catalyst (Desmorapid® Z from Bayer AG) and heated with stirring at 6O ⁰ C. At this temperature, 2.304.65 g of the above-described reaction product were added to the original during two hours with stirring. The resulting reaction mixture was stirred for 10 hours at 60 ⁰ C until an isocyanate content <0.1 wt .-% was reached. The resulting urethane (meth) acrylate (A111-3) had a solids content of 76.6 wt .-%, a glass transition temperature of 2 ° C, an acid number of 20 mg KOH / g and a content of olefinically unsaturated double bonds of 3.89 equ./kg on.

The powder dispersion (A1-3) was prepared by the secondary dispersion method by mixing the following ingredients (dissolved in methyl ethyl ketone) in the indicated Sequence, distilling off the organic solvents, replacement of the removed organic solvents by water and homogenizing the resulting mixture:

1,021, 995 parts by weight urethane (meth) acrylate (A111 -3), - 9,866 parts by weight Lutensol® AT 50 (commercial wetting agent from BASF

Aktiengesellschaft)

20.974 parts by weight of triethylamine,

11, 13 parts by weight of initiator BK (oligomeric benzpinacol silyl ether in

Triethyl phosphate / toluene from Bayer Distribution Service GmbH), 10.4 parts by weight of the commercial Byk® N leveling additive from Byk

Chemistry,

1,327,372 parts by weight of deionized water,

19.2 parts by weight of Acrysol® RM-8W (commercial associative thickener of the company

Rohm and Haas) and - 19.2 parts by weight of deionized water.

Examples 1 to 3 and Comparative Experiment V1

The preparation of the multicoating color coaters 1 to 3 (Examples 1 to 3) and the multicoat colorant coating V1 (Comparative Experiment V1)

For the preparation of the multicoating color coaters 1 to 3 of Examples 1 to 3, the basecoats 1 to 3 were first prepared.

Basecoat 1:

8.1 parts by weight of a 3% strength by weight aqueous solution of a synthetic sodium magnesium phyllosilicate (Laponite® from Laporte), 10 parts by weight of deionized water and 0.14 parts by weight of trimethylamine were initially charged. To this was added a mixture of 6.5 parts by weight of deionized water and Viscalex® HV 30 (commercial associative thickener from Ciba Specialty Chemicals based on a methacrylate copolymer), after which the resulting mixture was homogenized. Subsequently, a mixture of 0.4 parts by weight of Nopco® DSX 1550 (commercial associative thickener from Cognis Deutschland GmbH based on a hydrophobic polyurethane) and 7.8 parts by weight of deionized water was added, after which the resulting mixture was homogenized. To this template, a mixture of 33.9 parts by weight of the powder dispersion (A1-1) of Preparation Example 1, 0.3 parts by weight of tetramethyldecynediol (50 percent in butyl glycol), 9.45 parts by weight of a carbon black paste prepared from

- 57 parts by weight of the acrylated polyurethane dispersion according to the German

Patent Application DE 44 37 535 A1,

2 parts by weight of polypropylene glycol,

25 parts by weight of deionized water, 10 parts by weight of carbon monarch 1400 and - 6 parts by weight of neutralizing solution (dimethylethanolamine, 10% in

Water);

2.6 parts by weight of butylglycol, 2.4 parts by weight of 1-propoxy-2-propanol, 1.2 parts by weight of Solventnaphtha® and 2.4 parts by weight of Shellsol® T were metered in, after which the resulting mixture was homogenized.

To the mixture was added a solution of one part by weight of Pripol® 2033 (commercial fat diol from Uniqema) in 2.4 parts by weight of 1-propoxy-2-propanol, after which the resulting mixture was homogenized again.

Finally, a mixture of 3.3 parts by weight of a talc, made from

48.2 parts by weight of the acrylated polyurethane dispersion according to the German patent application DE 44 37 535 A1,

3 parts by weight of poly (propylene glycol), 28 parts by weight of talc,

19 parts by weight of deionized water,

1.4 parts by weight of the commercial dispersant Disperbyk® 184 from Byk Chemie and

Neutralization solution (dimethylethanolamine, 10% in water), corresponding to a pH of 8;

2 parts by weight of tributyl phosphate and 0.66 parts by weight of deionized water were added, after which the resulting basecoat 1 was homogenized. The basecoat 1 was used to produce the multicoat paint system 1. Basecoat 2:

The basecoat 2 was prepared like the basecoat 1, except that the powder dispersion (A1-2) of Preparation Example 2 was used in place of the powder dispersion (A1-1) of Preparation Example 1. The basecoat 2 was used to produce the multicoat paint system 2.

Basecoat 3:

The basecoat 3 was prepared in the same way as the basecoat 1, except that the powder dispersion (A1-3) of Preparation Example 3 was used instead of the powder dispersion (A1-1) of Preparation Example 1. The basecoat 3 was used to produce the multicoat paint system 3.

For the comparative experiment V1, the basecoat material V1 was prepared analogously to the instructions for the preparation of the basecoat 1, except that instead of the powder dispersion (A1-1), 33.9 parts by weight of an aqueous polyurethane resin dispersion were used. The basecoat V1 was used to produce the multicoat paint system V1.

Two series of multicoat colorant coatings 1 to 3 and V1 were prepared.

As test panels for the first series, smooth steel sheets were used, which had been coated with a conventional and known, cathodically deposited and baked, smooth electrocoating.

As test panels for the second series, rough steel sheets were used, which had been coated with a conventional and known, cathodically deposited and baked, rough electrodeposition coating.

For each series, one layer of the basecoats 2, 3 and V1 was applied to the electrodeposition coatings. After their application, the basecoat films 2, 3 and V1 were each pre-dried for 10 minutes at 80 ⁰ C.

In addition, in each case one layer of a commercial aqueous filler (Colorpro.RTM. I from BASF Coatings AG was applied, and during 10

Dried minutes at 8O ⁰ C dried. On this layer was in each case a layer of the

Basecoat 1 applied. The resulting basecoat film 1 also became during 10 Dried for minutes at 8O ⁰ C and irradiated with UV radiation of a dose of 1, 5 J / cm ² (iron-doped mercury vapor lamp from the company IST, measurement of the dose with Light Bug C) in the air.

Subsequently, in each case one layer of a commercially available clearcoat (ProGloss® from BASF Coatings AG) was applied to the dried basecoat films 2, 3 and V1 and the dried basecoat film 1 irradiated with UV radiation. The resulting clearcoat films were cured together with the basecoat films 1 to 3 and V1 for 20 minutes at 140 ⁰ C.

The multicoat system 1 was structured as follows:

Electrocoating 20 ± 2 μm, functional layer or filler 15 ± 2 μm, - base coating 12 ± 2 μm and

Clearcoat 35 ± 5 μm.

The multicoat paint systems 2 and 3 and V1 were constructed as follows:

Electrocoating 20 ± 2 μm,

Basecoat 18 ± 2 μm and clearcoat 35 ± 5 μm.

The basecoats 1 to 3 and V1 of the multicoat paint systems 1 to 3 and V1 had a high boiling limit of> 20 μm. Their intercoat adhesion was excellent before and after exposure to moisture for 240 hours in the constant climate test (cross cut test: GTO). Rock chip resistance was also very good (VDA: grade 2 to 2.5).

The course and the image distinctness (DOI) of the multicoat paint systems 1 to 3 were compared with the course and the image discrimination (DOI) of the multicoat paint system V1. The results were summarized in the table, with only the change of the values compared to the values of the multicoat paint system V1 (= standard). Table: History and Distinctness of Distinction (DOI) of the

Multicoat paint systems 1 to 3 of Examples 1 to 3 in comparison to the course and the image discrimination (DOI) of the multicoat paint system V1 of Comparative Experiment V1

Property multi-layer coating:

1 2 3

Course:

1st series:

Longwave - 4,2 - 4,2 - 3,7

Shortwave - 11, 3 - 11, 2 - 15.5

2nd series:

Longwave - 4 - 3.9 - 5.5

Short Wave - 8.2 - 8.3 - 9.3

Image Distinctness (DOI):

1st series: 1, 4 1, 5 4.1

2nd series: 1, 4 1, 4 1, 6

The results of the table underlined that the multicoat paint systems 1 to 3 had a significantly better leveling and a significantly higher image discrimination (DOI) than the multicoat paint system V1, so that they were able to prevent unevenness of substrates, for example due to poorer steel quality or worse The electrocoating had evoked much better balance. This also resulted in a much better flow and better distinctness of image (DOI) of the relevant clearcoats.

Claims

claims

1. A process for producing multicoat color and / or effect paint systems comprising at least one color and / or effect basecoat (A) and at least one transparent topcoat (B), in which

(2) the resulting color and / or effect layer (A), without fully curing, dries,

characterized in that the color and / or effect coating material (A) or at least one of the color and / or effect coating materials (A) is prepared by

(5) at least one, by radical polymerization curable, pseudoplastic, completely or substantially free of volatile organic compounds powder dispersion (A1) containing as a disperse phase solid and / or highly viscous under storage and application conditions dimensionally stable particles (A1 1) one with the

Photon correlation spectroscopy measured average particle size z mean of 80 to 750 nm, containing at least one radically crosslinkable binder (A1 1 1) having a glass transition temperature of -70 to + 5O ⁰ C, a content of olefinically unsaturated double bonds of 2 to 10 equ./kg and a content of acid groups from 0.05 to 15 equ./kg in one

Amount of, based on (A), 50 to 100% by weight, produced separately, (6) they are mixed with the other constituents (A2) of the color and / or effect coating material (A) and

(7) homogenize the resulting mixture (A).

2. The method according to claim 1, characterized in that the binder (A111) of the dimensionally stable particles (A11) of the powder dispersion (A1) has a number average molecular weight of 1,000 to 50,000 daltons.

3. The method according to claim 1 or 2, characterized in that the olefinically unsaturated double bonds of the binder (A1 1 1) of the dimensionally stable particles (A1 1) of the powder dispersion (A1) in groups selected from the group consisting of (meth) acrylate -, ethacrylate, crotonate, cinnamate, vinyl ether, vinyl ester, dicyclopentadienyl, norbornenyl, isoprenyl, isopropenyl, AlIIyI- or

butenyl; Dicyclopentadienyl, norbornenyl, isoprenyl, isopropenyl, allyl or butenyl ether groups or dicyclopentadienyl, norbornenyl, isoprenyl, isopropenyl, allyl or butenyl ester groups.

4. The method according to claim 3, characterized in that the olefinically unsaturated double bonds of the binder (A1 1 1) of the dimensionally stable particles (A1 1) of the powder dispersion (A1) are present in (meth) acrylate groups.

5. The method according to any one of claims 1 to 4, characterized in that the binder (A1 1 1) of the dimensionally stable particles (A11) of the powder dispersion (A1) from the group consisting of oligomeric and polymeric epoxy (meth) acrylates, urethane ( meth) acrylates and carbonate (meth) acrylates are selected.

6. The method according to claim 5, characterized in that the binder (A1 1 1) of the dimensionally stable particles (A1 1) of the powder dispersion (A1) is an oligomeric or polymeric urethane (meth) acrylate.

7. The method according to any one of claims 1 to 6, characterized in that the dimensionally stable particles (A1 1) of the powder dispersion (A1) have a measured by photon correlation spectroscopy mean particle size z mean of 80 to 400 nm.

8. The method according to any one of claims 1 to 7, characterized in that the powder dispersion (A1) nor at least one additive (A1 12) selected from the group consisting of residue-free or substantially residue-free thermally decomposable salts; from the binders (A1 1 1) different physically, thermally and / or actinic radiation curable binders; Neutralizing agents; thermally curable crosslinker; thermally curable reactive diluents; curable with actinic radiation reactive diluents; opaque and transparent, color and / or effect pigments; molecularly soluble dyes; opaque and transparent fillers; nanoparticles;

Light stabilizers; antioxidants; Venting means; Wetting agents; emulsifiers; slip additives; polymerization inhibitors; Initiators of radical polymerization, especially photoinitiators; thermolabile radical initiators; Adhesion promoters; Leveling agents; film-forming aids; Rheology auxiliaries, such as thickeners and pseudoplastic Sag control agents, SCA; Flame retardants;

Corrosion inhibitors; anti-caking agents; To grow; driers; Biocides and matting agents; contains.

9. The method according to any one of claims 1 to 8, characterized in that the powder dispersion (A1) is prepared by the particles (A1 1) in an aqueous

Medium (A12) dispersed.

10. The method according to claim 9, characterized in that dispersing the particles (A1 1) in an aqueous medium (A12) by a secondary dispersion method, wherein

dissolves the ionically stabilizable binders (A1 1 1) and optionally the additives (A1 12) in organic solvents,

the resulting solutions with the aid of neutralizing agents (A1 12) in

Water (A12) dispersed,

the resulting dispersion is diluted with water (A12), which initially forms a water-in-oil emulsion which turns into an oil-in-water emulsion on further dilution, and the organic solvents are removed from the oil-in-water emulsion.

11. The method according to any one of claims 1 to 10, characterized in that the color and / or effect multicoat paint systems one or more coats primer coatings, electrocoats, anti-corrosion coatings,

Rockfall protection primers and / or surfacer coatings included.

12. The method according to any one of claims 1 to 11, characterized in that irradiating the dried, colored and / or effect layer (A) after the process step (2) and before the process step (3) with actinic radiation.

13. The method according to any one of claims 1 to 12, characterized in that the cured, color and / or effect layer (A) and the transparent layer (B) in the process step (4) thermally cures together.

14. The method according to any one of claims 1 to 13, characterized in that the cured, color and / or effect layer (A) and the transparent layer (B) in the process step (4) cures together thermally and with actinic radiation.

15. The method according to any one of claims 12 to 14, characterized in that one uses as actinic radiation UV radiation.