EP3768751A1

EP3768751A1 - Aqueous uretdione group-containing compositions and method for producing same

Info

Publication number: EP3768751A1
Application number: EP19711129.7A
Authority: EP
Inventors: Dorota Greszta-Franz; Saskia BEUCK; Hans-Josef Laas; Nusret Yuva; Heinz-Dietmar Gewiss
Original assignee: Covestro Intellectual Property GmbH and Co KG; Covestro LLC
Current assignee: Covestro Deutschland AG; Covestro LLC
Priority date: 2018-03-23
Filing date: 2019-03-21
Publication date: 2021-01-27
Also published as: WO2019180130A1; CN112041367B; CN111886272B; CN111868131A; EP3768745A1; CN112041367A; EP3768756A1; EP3768747A1; WO2019180127A1; EP3768749A1; WO2019183307A1; CN111868135A; CN111886272A; WO2019180129A1; EP3768759A1; WO2019183315A1; WO2019183313A1; EP3768748A1; CN112105665A; EP3768755A1

Abstract

The invention relates to aqueous uretdione group-containing compositions comprising or consisting of (A) at least one uretdione group-containing curing agent based on aliphatic, cycloaliphatic, aliphatic and/or aromatic polyisocyanates which do not contain chemically bonded hydrophilating groups; (B) at least one polyacrylate copolymer; (C) optionally solvents; and (D) optionally auxiliary agents and additives; wherein the quantity ratio of the components (A) and (B) is measured such that the molar ratio of the NCO groups of the curing agent (A), said groups being provided in the form of uretdione, to the NCO reactive groups of the polyacrylate copolymer (B) equals 3.0 : 0.5 to 0.5 : 3.0, and A and B are provided as a physical mixture. The invention additionally relates to a method for producing a polyurethane layer using the aqueous uretdione group-containing composition according to the invention, to the polyurethane layer obtained therefrom, and to a substrate which is coated with or adhered to the polyurethane layer.

Description

Aqueous uretdione group-containing compositions and process for their preparation

The present invention relates to aqueous uretdione group-containing compositions comprising or consisting of

(A) at least one hardener containing uretdione groups, based on aliphatic, cycloaliphatic, araliphatic and / or aromatic polyisocyanates, which contains no chemically bonded hydrophilizing groups;

(B) at least one polyacrylate copolymer;

(C) optionally solvent; and

(D) optionally auxiliaries and additives;

wherein the quantitative ratio of components (A) and (B) is such that the molar ratio of the uretdione present NCO groups of the harder (A) to NCO-reactive groups of the polyacrylate copolymer (B) 3: 0.5 to 0 , 5: 3 and wherein A and B are present as a physical mixture.

Moreover, the invention relates to a process for producing a polyurethane layer using the aqueous uretdione group-containing composition of the present invention, the polyurethane layer obtained therefrom, and a substrate coated or adhered to this polyurethane layer.

In recent years, the importance of aqueous lacquers and coating agents has risen sharply due to ever stricter emulsion strains with regard to the solvents released in the paint application. Although aqueous coating systems are already available for many applications, they often can not achieve the high quality level of conventional, solvent-borne coatings in terms of resistance to solvents and chemicals or even elasticity and mechanical stress. In particular, hitherto, no coating compositions to be processed from an aqueous phase have become known on the basis of polyurethane, which satisfies the high demands of practice to a sufficient extent. This finding applies both to DE 4001783 A1, which deals with special anionically modified aliphatic polyisocyanates, and to the systems of DE 2456469 A1, DE 2814815 A1, EP 0012348 A1 and EP 0424697 A1, the aqueous one-component stoving binder based on blocked polyisocyanates and organic polyhydroxyl compounds.

In recent years, further improvements of the one-component stoving binder based on blocked polyisocyanates have been achieved, as described for example in EP 0576952 A. The above, the prior art, one-component, based on blocked polyisocyanates, baked-on binder have the disadvantage that, even if they are largely solvent-free, the respective blocking agents are set free when baking these paint binders, which in turn contributes to emissions. Therefore, there has long been a need in the market to develop aqueous, emission-free one-component stoving binder. There has been no lack of attempts to produce such stoving binder based on splitter-free, uretdione-containing polyisocyanates. According to EP 1687354 A1, aqueous uretdione-containing dispersion coatings can be prepared by combining a solid uretdione compound with a molten water-dispersible resin, salting the water-dispersible resin if necessary, and dispersing the resin composition in water. The molten water-dispersible resin may have a functionality reactive with the uretdione compound, or the coating composition may contain another water-dispersible resin having a uretdione compound-reactive functionality. In the example, however, an epoxy resin was used. It is generally known that the epoxy varnishes are inferior to the polyurethane varnishes in most properties. According to EP 1687354 A1, it is also necessary for the preparation of these dispersion coatings to use an additional emulsifier, which further impairs the coating properties of the dispersion coatings.

In addition, the production method described in EP 1687354 A1 is associated with a very high thermal load for the uretdione groups, which in practice would most likely lead to a loss of the uretdione groups. Furthermore, the dispersions described in EP 1687354 Al were applied immediately after preparation. There is no information in EP 1687354 Al about the stability of these dispersions.

US 2015232609A1 discloses water-dispersible hydrophilic uretdione-containing polyisocyanates obtainable by reacting a uretdione-bearing prepolymer with an emulsifier comprising an ionogenic group, the ionogenic group having either a pKa> 8 or a pKb> 8 in the water at room temperature. Such uretdione-containing reaction products showed an improved storage stability of 8 weeks at room temperature, but this is still insufficient for practical applications in industry, where not infrequently long transport distances must be expected. Surprisingly, the above problems have been solved by the use of a physical mixture of the specific hardener and the polyacrylate copolymer of the present invention. In particular, dispersions could be obtained which have an increased storage stability compared to the compositions known in the prior art.

The present invention particularly relates to:

1. Aqueous uretdione group-containing compositions comprising or consisting of

(A) at least one hardener containing uretdione groups, based on aliphatic, cycloaliphatic, araliphatic and / or aromatic polyisocyanates, preferably based on aliphatic, cycloaliphatic, and / or araliphatic polyisocyanates, particularly preferably based on aliphatic and / or cycloaliphatic polyisocyanates, which does not chemically bound hydrophilicizing groups;

(B) at least one polyacrylate copolymer;

(C) optionally solvent; and

(D) optionally auxiliaries and additives;

wherein the ratio of components (A) and (B) is such that the molar ratio of the uretdione NCO groups of the harder (A) to NCO-reactive groups of the polyacrylate copolymer (B) is 3.0: 0, 5 to 0.5: 3.0, preferably from 2.5: 1.0 to 1.0: 2.5; more preferably 2.0: 1.0 to 1.0: 2.0 and wherein (A) and (B) exist as a physical mixture.

2. Aqueous uretdione group-containing composition according to aspect 1, characterized in that

the at least one uretdione group-containing hardener (A) by reacting monomeric isocyanates comprising or consisting of at least one monomeric isocyanate selected from tetramethylene diisocyanate, cyclohexane-1,3- and 1,4-diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate (HDI), 1-isocyanato-3,3,5-trimethyl-5-i so cyanoatomethyl cy clohexane (isophorone diisocyanate IPDI), dicyclohexylmethane-2,4'- and / or 4,4'-diisocyanate, tetramethylxylylene diisocyanate (TMXDI), Trii so cy anatononan, T oluylenediisocyanat (TDI), diphenylmethane-2,4'- and / or 4,4'-diisocyanate (MDI), triphenylmethane-4,4'-diisocyanate or naphthylene-1, 5-diisocyanate or mixtures thereof, preferably from Isophorone diisocyanate, dicyclohexylmethane-2,4'- and / or 4,4'-diisocyanate or hexamethylene diisocyanate was obtained. 3. Aqueous uretdione group-containing composition according to aspect 1 or 2, characterized in that as feedstocks for the at least one uretdione group-containing hardener (A) hydroxyl-containing monomers and / or polymers are used.

4. Aqueous uretdione group-containing composition according to one of the preceding aspects, characterized in that

the at least one uretdione group-containing hardener (A) has a free NCO content of less than 5% by weight and a content of uretdione groups of 1 to 18% by weight, calculated as C2N2O2, molecular weight 84 g / mol.

5. Aqueous uretdione group-containing composition according to one of the preceding aspects, characterized in that

the aqueous composition has an acid number of 1 to 100 mg KOH / g, preferably 2 to 50 mg KOH / g, more preferably 5 to 30 mg KOH / g, preferably measured according to DIN EN ISO 2114: 2002-06 with acetone and ethanol in a weight ratio 2: 1 as a solvent, and calculated on solids content.

6. Aqueous uretdione group-containing composition according to one of the preceding aspects, characterized in that

the at least one polyacrylate copolymer (B) is obtained by reacting a mixture of free-radically polymerizable monomers (M) comprising or consisting of (Ml) hydroxyl and carboxyl-free (meth) acrylic esters with CI to CI 2 hydrocarbon radicals in the alcohol unit;

(M2) Hydroxyl-functional, radically polymerizable monomers;

(M3) carboxyl-functional, free-radically polymerizable monomers;

(M4) optionally vinyl esters of aliphatic carboxylic acids;

(M5) optionally at least one cycloaliphatic ester of (meth) acrylic acid and / or vinylaromatics.

7. Aqueous uretdione group-containing composition according to one of the preceding aspects, characterized in that

the at least one hydroxyl group-containing polyacrylate copolymer (B) has an OH content of more than 1% by weight - calculated as OH group to solid content, molecular weight 17 g / mol - and a number average molecular weight Mn of 500 to 20,000 g / mol. 8. Aqueous uretdione according to one of the preceding aspects, characterized in that the solvent title is selected from acetone, methyl ethyl ketone, ethyl acetate, butyl acetate, xylene, heavy benzene, such as the commercially available Solvesso 100 or Solvesso 150, propyl englykolmono-n-butyl ether, dipropylene glycol dimethyl ether, methoxypropyl acetate, dibasic esters or mixtures thereof. Aqueous uretdione dispersion according to one of the preceding aspects, characterized in that

the auxiliaries and additives are selected from the group of flow control agents, for example polysilicones or acrylates, light stabilizers, for example sterically hindered amines, catalysts, for example tin (II) 2-ethylhexanoate or dibutyltin dilaurate, fillers and pigments, for example titanium dioxide, or Mixtures thereof.

Aqueous uretdione group-containing composition according to one of the preceding aspects, characterized in that

the sum of the weight fractions of (A), (B) and (D) is from 30 to 60% by weight, based on the solids content of the total aqueous composition. Process for the production of a polyurethane layer, comprising the steps

i) providing an aqueous uretdione group-containing composition according to any one of aspects 1 to 10;

ii) applying the mixture obtained under i) to a substrate;

iii) drying the mixture from step ii), and

iv) flashing the mixture from step iii) with heat from 40 ° C to 180 ° C for up to 180 minutes. Process according to aspect 11, characterized in that the aqueous composition containing uretdione groups has been obtained by mixing the uretdione group-containing dyeing agent (A) with the at least one polyacrylate copolymer (B) in the absence of water and subsequent dispersion with water. Polyurethane layer, in particular polyurethane film, obtainable by a process according to aspect 11 or 12. A substrate which is coated or glued with the polyurethane chi cht according to aspect 13. Unless otherwise stated in the present invention, molecular weights are determined by GPC (gel permeation chromatography) using polystyrene standards. The average molecular weight according to this invention is defined as the number average molecular weight Mn. Mn is determined at 23 ° C in tetrahydrofuran as the solvent. The measurement is carried out as described in DIN 55672-1: 2007-08 "Gel Permeation Chromatography, Part 1 - Tetrahydrofuran as Eluent" with a SECURITY GPC System from PSS Polymer Service, flow rate 0.6 ml / min.

Unless otherwise stated, percentages by weight in the present invention refer to the total weight of the particular system or the total weight of the particular component. For example, a copolymer may contain a given monomer in weight percent, in which case the weight percentages would be based on the total weight of the copolymer.

Unless otherwise stated, the term "at least one" refers to the nature of the compounds rather than individual molecules. For example, at least one copolymer is to be understood to contain at least one type of copolymer, but it is contained in an arbitrary number of molecules in the composition. Thus, there may also be two or more types of copolymers each in an arbitrary number, if the amounts are not defined.

In a preferred embodiment, the aqueous uretdione group-containing composition is substantially free of another co-emulsifier (in addition to component (B)). The term "substantially free of" according to the present invention is defined as preferably less than 1 wt%, more preferably less than 0.25 wt%, even more preferably less than 0.1 wt%. , most preferably less than 0.01 wt .-% or no fraction of the respective compound, each based on the total weight of the aqueous uretdione groups-containing composition.

The aqueous uretdione group-containing composition of the present invention is preferably a polyurethane-based composition.

Suitable polyisocyanates containing uretdione groups as starting compounds for component (A) are polyisocyanates containing at least one isocyanate group and at least one uretdione group. These are prepared, as described, for example, in WO 02/92657 A1 or WO 2004/005364 A1 by reaction of suitable starting isocyanates (al). Here, under catalysis, for example with triazolates or 4-dimethylaminopyridine (DMAP) as catalysts, a portion of the isocyanate groups in Ur etdiongrupp s transferred. examples for Isocyanates (a1), from which the uretdione-containing building blocks are built up, are tetramethylene diisocyanate, cyclohexane-1,3- and 1,4-diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate (HDI), 1-isocyanato-3, 3,5-trimethyl -5-isocyanatomethylcyclohexane (isophorone diisocyanate IPDI), dicyclohexylmethane-2,4'- and / or 4,4'-diisocyanate,

Tetramethylxylylene diisocyanate (TMXDI), triisocyanatononane, tolylene diisocyanate (TDI), diphenylmethane-2,4'- and / or 4,4'-diisocyanate (MDI), tripfaenylmethane-4,4'-diisocyanate or naphthylene-1, 5-diisocyanate and any mixtures of such isocyanates. Isophorone diisocyanate, dicyclohexylmethane-2,4'- and / or 4,4'-diisocyanate or are preferred

Hexamethylene diisocyanate.

In addition to the isocyanate groups and uretdione groups, component (A) may also have isocyanurate, biuret, allophanate, urethane and / or hamsto ff structures.

The reaction of these uretdione group-bearing polyisocyanates to uretdione groups having Hartem (A) involves the reaction of the free NCO groups of the above polyisocyanates with a polyol component (bl), optionally with the concomitant use of the polyol component (b2).

The polyol component (bl) preferably has a hydroxyl group functionality of> 2 and a molecular weight M _n of 62 to 500 g / mol, preferably 62 to 400 g / mol, particularly preferably 62 to 300 g / mol. The polyol component (bl) preferably contains 2- to 6-valent polyol components of molecular weight Mn of 62 to 500 g / mol, preferably 62 to 400 g / mol, particularly preferably 62 to 300 g / mol. Preferred polyol components (bl) are, for example, 1,4- and / or 1,3-butanediol, 1,6-hexanediol, 2,2,4-trimethyl-1,3-pentanediol, trimethylolpropane, polyester and / or polyether polyols of the middle one Molar weight M _n of less than or equal to 500 g / mol.

Suitable linear difunctional polyols (b2) are selected from the group of polyethers, polyesters, polycaprolactone diols and / or polycarbonates. The polyol component (b2) preferably comprises at least one diol containing ester groups and having a molecular weight Mn of from 350 to 4000 g / mol, preferably from 350 to 2000 g / mol, more preferably from 350 to 1000 g / mol. In general, the ester diols are mixtures in which, in minor amounts, individual constituents may also be present which have a molecular weight below or above these limits. These are the polyester diols known per se, which are built up from diols and dicarboxylic acids. Suitable diols are, for example, 1,4-dimethylolcyclohexane, 1,4- or 1,3-butanediol, 1,6-hexanediol, neopentyl glycol, 2,2,4-trimethyl-1,3-pentanediol, trimethylolpropane and also pentaerythritol or mixtures thereof diols. Suitable dicarboxylic acids are, for example, aromatic dicarboxylic acids such as phthalic acid, isophthalic acid and terephthalic acid, cycloaliphatic dicarboxylic acids such as hexahydrophthalic acid, tetrahydrophthalic acid, endomethylenetetrahydrophthalic acid or its anhydrides and aliphatic dicarboxylic acids which are preferably used, such as succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid and Sebacic acid or its anhydrides.

Polyester diols based on adipic acid, phthalic acid, isophthalic acid and tetrahydrophthalic acid are preferably used as component (b2). Examples of preferred diols are 1,4- or 1,3-butanediol, 1,6-hexanediol or trimethylolpropane and mixtures thereof.

Also preferred as component (b2) are polycaprolactone diols of average molecular weight from 350 to 4000 g / mol, preferably from 350 to 2000 g / mol, particularly preferably from 350 to 1000 g / mol, which in a conventional manner from a diol or diol mixture the type exemplified above as a starter, and lactones such as .beta.-propiolactone, g-butyrolactone, g- and d-valerolactone, e-caprolactone, 3,5,5- and 3,3,5-T rimethylcaprolacton or any mixtures thereof Lactones have been produced. Particularly preferred are those polycaprolactone diols which have been prepared by polymerization of e-caprolactone.

As the linear polyol component (b2) it is also possible to use (co) polyethers of ethylene oxide, propylene oxide and / or tetrahydrofuran, which consist of less than 30 mol% of ethylene oxide units. Preferred are polyethers having an average molecular weight Mn of from 500 to 2000 g / mol, such as e.g. Polypropylene oxides or polytetrahydrofurandiols.

Also suitable as (b2) are hydroxyl-containing polycarbonates, preferably average molecular weight Mn of from 400 to 4000 g / mol, preferably from 400 to 2000 g / mol, for example hexanediol polycarbonate and polyestercarbonates.

As polyol component (b2) in the preparation of uretdione groups having curing agent (A) and low molecular weight ester-containing diols of a mean, from functionality and Hydro xylzahl calculable molecular weight of 134 to 349 g / mol, preferably 176 to 349 g / mol, are used , These are, for example, the per se known ester groups having diols or mixtures of such diols, such as by reaction of alcohols with minor amounts of dicarboxylic acids, corresponding Di carbonsäureanhydriden, corresponding Dicarbonsäureestem create lower alcohols or lactones h. Examples of suitable acids are succinic acid, adipic acid, sebacic acid, phthalic acid, isophthalic acid, phthalic anhydride, tetrahydrophthalic acid, maleic acid, maleic anhydride, dimethyl maleate and terephthalic acid bis-glycol ester. Suitable lactones for the preparation of these ester diols are, for example, β-propiolactone, g-butyrolactone, g- and d-valerolactone, ε-caprolactone, 3,5,5- and 3,3,5-trimethyl-caprolactone or any desired mixtures of such lactones.

In the preparation of Uretdiongrupp en having hardener (A) and amino-functional compounds can be used. Examples of suitable low molecular weight amino-functional compounds are aliphatic and cycloaliphatic amines and amino alcohols having primary and / or secondary bound amino groups, such as. B. cyclohexylamine, 2-methyl-l, 5-pentanediamine, diethanolamine, monoethanolamine, propylamine, butylamine, dibutylamine, hexylamine, monoisopropanolamine, diisopropanolamine, ethylenediamine, 1, 3-diaminopropane, 1,4-diaminobutane, isophoronediamine, di ethyl entriamin, Ethanolamine, aminoethyl-ethanolamine, diaminocyclohexane, hexamethylenediamine, methyliminobispropylamine, iminobispropylamine, bis (aminopropyl) piperazine, aminoethylpiperazine, 1,2-diaminocyclohexane, triethyl-entetramine, tetraethylpentamine, bis (4-amino-cyclohexyl) methane, bis (4-amino-3-methylcyclohexyl) methane, bis (4-amino-3,5-dimethylcyclohexyl) methane, bis (4-amino-2,3,5-trimethylcyclohexyl) methane, 1,1 - bis (4-aminocyclohexyl) propane, 2,2-bis (4-aminocyclohexyl) propane, 1,1-bis (4-aminocyclohexyl) ethane, 1,1-bis (4-aminocyclohexyl) butane, 2,2-bis (4-aminocyclohexyl) butane, 1,1-bis (4-amino-3-methylcyclohexyl) ethane, 2,2-bis (4-amino-3-methylcyclohexyl) propane, 1,1-bis (4- amino -3,5 -dimethylcyclohexyl) ethane, 2,2-bis (4-amino-3,5-dimethylcyclohexyl) propane, 2,2-bis (4-amino-3,5-dimethyl-dimethoxy) butane, 2,4-diaminodicyclohexylmethane, 4-aminocyclohexyl-4-amino-3 -methylcyclohexylmethane, 4-amino-3,5-dimethyl cyclohexyl-4-amino-3-methylcyclohexylmethane and 2- (4-aminocyclohexyl) -2- (4-amino-3-methylcycloxy) methane.

If necessary, solvents may be used in the preparation of the curing agent (A) containing uretdione groups. Suitable solvents for uretdione curing agents (A) are all liquid substances which do not react with other ingredients, eg. Acetone, ethyl ethyl ketone, ethyl acetate, butyl acetate, xylene, heavy benzene, such as the commercially available Solvesso 100 and Solvesso 150, propylene glycol mono-n-butyl ether, dipropylene glycol dimethyl ether, methoxypropyl acetate, dibasic esters or mixtures thereof.

The uretdione group-containing hardeners (A) are substantially free of ionic or non-ionic, chemically-bonded hydrophilicizing groups. Among the ionic Hydrophilizing groups, the expert understands groups that have an ability for anion or cation formation. Groups capable of anion or cation formation are those which can be converted by chemical reaction into an anionic or cationic group, in particular by neutralization.

The uretdione group-containing curing agents (A) are preferably free of anionic-capable, carboxyl-containing polyols or diols, e.g. Dihydroxycarboxylic acids, such as α, α-dialkylolalkanoic acids, in particular α, α-dimethylolalkanoic acids, such as 2,2-dimethylolacetic acid, 2,2-dimethylolpropionic acid, 2,2-dimethylolbutyric acid, 2,2-dimethylolpentanoic acid,

Dihydroxy succinic acid, or polyhydroxy acids, such as gluconic acid. Furthermore, the hardeners (A) containing uretdione groups are preferably free from amino-containing compounds capable of anion formation such as, for example, α, W-diaminovaleric acid or 2,4-diamino-toluene-sulphonic acid. The curing agents (A) having primary groups are likewise preferably free of anionic sulfonic acid groups.

In addition, uretdione hardening agents (A) are preferably free of cation-forming compounds from the group of tertiary amino or ammonium compounds, e.g. Tris (hydroxyalkyl) amines, N, N'-bis (hydroxyalkyl) alkylamines, N-hydroxyalkyldialkylamines, trisaminoalkylamines, N, N'-bisaminoalkylalkylamines, N-aminoalkyldialkylamines, and mixtures thereof.

The uretdione group-containing hardeners (A) are furthermore preferably free of nonionically hydrophilizing compounds, such as, for example, polyalkylene oxide polyether alcohols or polyalkylene oxide polyetheramines. In particular, the hardeners (A) containing uretdione groups are preferably free of polyethylene oxide polyethers or mixed polyalkyleneoxy polyethylenes whose alkylene oxide units consist of at least 30 mol% of ethylene oxide units.

Preferred uretdione hardeners (A) have a free NCO content of less than 5% by weight and a content of uretdione groups of 1 to 18% by weight (calculated as C2N2O2, molecular weight 84 g / mol). In addition to the uretdione groups, the hardeners (A) may also have isocyanurate, biuret, allophanate, urethane and / or urea structures.

The composition also contains at least one polyacrylate copolymer (component (B)). According to the present invention, the term "polyacrylate copolymer ¹ " encompasses both polyacrylate copolymers and poly (meth) acrylate copolymers. Suitable polyacrylate copolymers can be obtained, for example, by the synthesis of the following mixture of radically polymerizable monomers (M):

(Ml) Hydroxyl and carboxyl-free (meth) acrylic esters with CI to C12 hydrocarbon radicals in the alcohol unit;

(M2) Hydroxyl-functional, radically polymerizable monomers;

(M3) carboxyl-functional, free-radically polymerizable monomers;

(M4) optionally vinyl esters of aliphatic carboxylic acids;

The mixture may further optionally contain polyols (PO) selected from the group of polyester polyols and / or polycarbonate polyols, wherein the polyols have a mean Hy droxylgrupp enfunktionalität of at least 2.

The polyacrylate dispersions according to the invention can have high hydroxyl group contents, so that, without being bound by theory, a higher degree of crosslinking and thus higher hardness of the coatings can be achieved.

In the context of the present invention, acrylic acid or methacrylic acid are also referred to as (meth) acrylic acid.

As hydroxyl and carboxyl free monomers (Ml) are used acrylates and methacrylates having 1 to 18 carbon atoms in the alcohol part of the ester group. The alcohol moiety is preferably aliphatic and may be linear or branched.

Examples of suitable monomers of component (III) are methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, the isomeric pentyl, hexyl, 2-ethylhexyl , Octyl and dodecyl (meth) acrylates. Preferred monomers (Ml) are methyl, n-butyl, isobutyl, tert-butyl (meth) acrylate and 2-ethylhexyl acrylate and styrene.

Suitable hydroxy-functional monomers (M2) are ethylenically unsaturated, hydroxyl-containing monomers such as hydroxyalkyl esters of unsaturated carboxylic acids, preferably hydroxyalkyl (meth) acrylates having 2 to 12, preferably 2 to 6 carbon atoms in the hydroxyalkyl radical. Examples of particularly preferred compounds are 2-

Hydroxy ethyl (meth) acrylate, the isomeric hydroxypropyl (meth) acryl late, 2, 3 and 4 Hydroxybutyl (meth) acrylates and the isomeric hydroxyhexyl (meth) acrylates. Preference is given to 4-hydroxybutyl acrylate (butanediol monoacrylate) and hydroxyethyl methacrylate.

Suitable carboxyl-functional free-radically polymerizable monomers (M3) are olefinically unsaturated monomers containing carboxylic acid or carboxylic anhydride groups, such as acrylic acid, methacrylic acid, beta-carboxyethyl acrylate, crotonic acid, fumaric acid, maleic anhydride, itaconic acid or monoalkyl esters of dibasic acids or anhydrides, such as maleic acid monoalkyl esters. Acrylic acid and / or methacrylic acid are preferred.

Suitable vinyl esters of aliphatic carboxylic acids (M4) may be included. Examples of these monomers are the esterification products of vinyl alcohol with linear or branched, aliphatic carboxylic acids such as vinyl acetate, vinyl propionate, vinyl butyrate, vinyl 2-ethylhexanoate, vinyl octanoate, vinyl decanoate, vinyl neodecanoate, vinyl dodecanoate (vinyl laurate) or vinyl stearate.

Suitable monomers (M5) are, for example, cyclohexyl (meth) acrylate, alkyl group-substituted cyclohexyl (meth) acrylates, 4-tert-butylcyclohexyl (meth) acrylate,

Norbornyl (meth) acrylate, isobornyl (meth) acrylate, isobornyl acrylate and / or isobornyl methacrylate and more preferably isobornyl methacrylate. It is also possible to use mixtures comprising isobornyl acrylate and isobornyl methacrylate and other monomers (M5). Particularly suitable vinylaromatics are styrene, optionally substituted styrenes and vinyltoluenes. The monomers (M5) other than isobornyl acrylate and isobornyl methacrylate may optionally be used in amounts of less than 10% by weight, based on the total weight of (Ml) to (M5).

Optionally, other monomers (M6) such as acetoaceto xyethylmethacrylat, acrylamide, acrylonitrile, vinyl ethers, methacrylonitrile or vinyl acetates may be included. In addition, proportionally monofunctional polyalkylene oxides having molecular weights of 200 to 3000 g / mol, preferably 350 to 1000 g / mol, or esterified (meth) acrylic acid, which are suitable as nonionic, hydrophilic groups, can be used. Suitable alkylene oxides preferably include ethylene oxide or mixtures of ethylene oxide and propylene oxide. Preferably, however, the hydrophilization of the copolymers is carried out by ionic groups, ie monomers (M3).

The proportions of the monomers (III) to (M6) can be selected such that the polyacrylate copolymer has an OH number (DIN EN ISO 4629-1: 2016-12) of 50 to 400 mg KOH / g, preferably from 100 to 300 mg KOH / g solids. With respect to the polyester polyols and / or polycarbonate polyols (PO), it is preferred that the average hydroxyl group functionality be at least 2.5. Suitable polyester polyols are the known polycondensates of poly (tri, tetra) ols and di- and optionally poly (tri, tetra) - carboxylic acids or hydroxycarboxylic acids or lactones.

Instead of the free polycarboxylic acids, it is also possible to use the corresponding polycarboxylic anhydrides or corresponding polycarboxylic acid esters of lower alcohols to prepare the polyesters. Examples of suitable alcohols are trimethylolpropane, glycerol, erythritol, pentaerythritol, trimethylolbenzene or trishydroxyethyl isocyanurate.

Examples of suitable dicarboxylic acids include phthalic acid, isophthalic acid, terephthalic acid, tetrahydrophthalic acid, hexahydrophthalic acid, cyclohexanedicarboxylic acid, adipic acid, azelaic acid, sebacic acid, glutaric acid, tetrachlorophthalic acid, maleic acid, fumaric acids, itaconic acid, malonic acid, suberic acid, 2-methylsuccinic acid, 3,3- Diethyl glutaric acid and 2,2-dimethyl succinic acid. The possible anhydrides of these acids are also suitable. For the purposes of the present invention, therefore, the anhydrides are encompassed by the term "acid". It is also possible to use monocarboxylic acids, such as benzoic acid, hexanecarboxylic acid or fatty acids, provided that the average functionality of the polyol is greater than 2. Saturated aliphatic or aromatic acids are preferred, such as adipic acid or isophthalic acid. In smaller amounts, polycarboxylic acids such as trimellitic acid can be used. Examples of hydroxycarboxylic acids that can be used as reactants in the preparation of a hydroxyl-terminated polyester polyol include hydroxycaproic acid, hydroxybutyric acid, hydroxydecanoic acid or hydroxy stearic acid. Examples of suitable lactones include e-caprolactone or butyrolactone.

The suitable hydroxyl-containing polycarbonates are obtainable by reacting carbonic acid derivatives, for example diphenyl carbonate, dimethyl carbonate or phosgene with polyols. Examples include ethylene glycol, 1,2- and 1,3-propanediol, 1,3- and 1,4-butanediol, 1,6-hexanediol, 1,8-octanediol, neopentylglycol, 1,4-bishydroxymethylcyclohexane, 2- Methyl-1, 3-propanediol, 2,2,4-trimethylpentane-l, 3-diol, dipropylene glycol, polypropylene glycols, dibutylene glycol, polybutylene glycols, bisphenol A, T etrabrombisphenol A, but also lactone-modified diols. The diol component preferably contains 40 to 100% by weight of hexanediol, preferably 1,6-hexanediol and / or hexanediol derivatives, more preferably those which contain ether or ester groups in addition to terminal OH groups. In order to obtain the desired functionality of at least 2, the polycarbonate polyols include branching through the incorporation of polyfunctional components, especially low molecular weight polyols. Examples of compounds which are suitable for this purpose include glycerol, trimethylolpropane, hexane-l, 2,6-triol, butane-l, 2,4-triol, trimethylolpropane, pentaerythritol, quinitol, marinitol and sorbitol, methyl glycoside or 1, 3, 4, 6-dianhydrohexitol e. The preparation of the polyacrylate copolymer can in principle be carried out by means of conventional free radical polymerization in organic phase. The polyacrylate copolymer is preferably prepared in a multi-stage process, as already described in EP-A 0 947 557 or in EP-A 1 024 184. In this method, first a hydrophobic monomer mixture, which is free of acid groups or with a low acid group content added, and then at a later time in the polymerization, a hydrophilic monomer mixture, containing acid groups, added, wherein the hydrophilic monomer mixture contains acid groups which are not monomers from Type (M4) and (M5) included. The copolymerization is generally carried out at 40 to 180 ° C, preferably at 80 to 160 ° C. Suitable initiators (I) for the polymerization reaction include organic peroxides such as di-tert-butyl peroxide, or tert-butyl peroxy-2-ethylhexanoate and azo compounds.

The amount of initiator used depends on the desired molecular weight. For reasons of operational safety and easier handling and peroxide initiators can be used in the form of a solution in suitable organic solvents of the type already mentioned. The rate of addition of the initiator (I) in the process of the invention may be controlled to continue until the end of the monomer feed, and the amounts of solvent in steps one and two are chosen so that an organic solvent content of less than 20 wt .-% results.

The amounts of the ingredients are preferably calculated so as to give a mass ratio of (Ml): (M2) of 9: 1 to 6: 1, particularly preferably a mass ratio of (Ml): (M2) of 4: 1 to 3: 1. (Ml) is also preferably: (M3) from 50: 1 to 40: 1, particularly preferably (Ml): (M3) from 35: 1 to 30: 1. Also preferred is (Ml): (M5) from 9: 1 to 6: 1, especially preferred is (Ml) :( M5) from 6: 1 to 5: 1.

The radical polymerization can be carried out in the presence of a solvent or solvent / water mixture that is filled into the reaction vessel. Suitable organic solvents are all known in Lackte chnologi e known solvents, with those are preferred, which are usually used as cosolvents in aqueous dispersions, such as alcohols, ethers, ethers containing ether groups, esters, ketones or nonpolar hydrocarbons or mixtures of these solvents , The Solvents are used in amounts such that their proportion in the finished dispersion is 0 to 20% by weight, preferably 0.1 to 15% by weight.

It is furthermore possible to prepare the polyacrylate copolymer by the process of EP-A 1 024 184, using as a template a hydrophobic copolymer. Instead of a multistage polymerization process, it is likewise possible to carry out the process according to the invention continuously (gradient polymerization), ie a monomer mixture having a changing composition is added, the hydrophilic (acid-functional) monomer fractions being higher at the end of the feed than at the beginning. The number average molecular weight Mn of the polyacrylate copolymers can be set by a specific choice of the operating parameters, for example the molar monomer / initiator ratio, for example the reaction time or the temperature, generally between 500 g / mol and 30,000 g / mol, preferably between 1,000 g / mol and 15,000 g / mol, more preferably between 1,500 g / mol and 10,000 g / mol. The hydroxyl group content of the polyacrylate copolymers in 100% form is preferably 1.5 to 12.0% by weight, preferably 2.0 to 10.0% by weight and more preferably 1.5 to 9.0% by weight

Before, during or after mixing the polyacrylate copolymers with the at least one uretdione group-containing curing agent (A), the acid groups present of the polyacrylate copolymers are preferably converted into their salt form by adding suitable neutralizing agents, at least proportionally. Suitable neutralizing agents are organic amines or water-soluble inorganic bases, such as, for example, soluble metal hydroxides, metal carbonates or metal hydrogencarbonates, for example sodium hydroxide or potassium hydroxide.

Examples of suitable amines are butyldiethanolamine, N-methylmorpholine, triethylamine, ethyldiisopropylamine, N, N-dimethylethanolamine, N, N-dimethylisopropanolamine, N-methyldiethanolamine, diethylethanolamine, triethanolamine, butanolamine, morpholine, 2-aminomethyl-2-methylpropanol or isophoronediamine. In mixtures, it is also possible to use proportionate ammonia. Particularly preferred are triethanolamine, N, N-dimethylethanolamine and ethyldiisopropylamine.

In one embodiment, the mixture of radically polymerizable monomers (M) does not contain: (M4) vinyl esters of aliphatic carboxylic acids. Examples of these monomers to be avoided are the esterification products of vinyl alcohol with linear or branched, aliphatic carboxylic acids such as vinyl acetate, vinyl propionate, vinyl butyrate, vinyl 2-ethylhexanoate, vinyl octanoate, vinyl decanoate, vinyl neodecanoate, vinyl dodecanoate (vinyl laurate) or vinyl stearate. In a further embodiment, the mixture of free-radically polymerizable monomers (M) does not contain: (M5): cycloaliphatic esters of (meth) acrylic acid and / or vinylaromatics. Examples of these monomers to be avoided are cyclohexyl (meth) acrylate, alkyl group-substituted cyclohexyl (meth) acrylates, 4-tert-butylcyclohexyl (meth) acrylate, norbornyl (meth) acrylate, isobornyl (meth) acrylate, isobornyl acrylate and / or isobornyl methacrylate and / or mixtures of the above monomers.

In another embodiment, the polyacrylate copolymer in 100% form has a hydroxyl group content of> 1.5 wt .-% to <12.0 wt .-%, preferably from> 2.0 wt .-% to <10.0 wt. -% on. The hydroxyl group content can be calculated by dividing by 33 the hydroxyl number determined as described above.

In a further embodiment, the polyols (PO) have a hydroxyl group content of> 15 wt .-% to <35 wt .-%, preferably from> 20 wt .-% to <30 wt .-%, on. Of the

Hydroxyl group content can be calculated by dividing the hydroxyl number determined by 33 as described above.

In another embodiment, the polyols (PO) are polyester polyols obtained from the reaction of an at least tri-functional alcohol with a lactone. A particularly preferred polyol is obtained from trimethylolpropane and e-caprolactone. For example, trimethylolpropane and e-caprolactone can be reacted in a weight ratio of> 60:40 to <80:20, preferably> 68:32 to <72:28. Optionally, the reaction may take place in the presence of a catalyst.

In a further embodiment, the monomers (III), (M2), (M3), (M4) and (M5) are used in the following amounts:

(Ml)> 25% by weight to <90% by weight, preferably> 30% by weight to <80% by weight,

(M2)> 8% by weight to <50% by weight, preferably> 30% by weight to <45% by weight,

(M3)> 1% by weight to <10% by weight, preferably> 2% by weight to <5% by weight,

optionally (M4)> 1 wt .-% to <10 wt .-%, preferably> 1.5 wt .-% to <5 wt .-%, optionally (M5)> 5 wt .-% to <40 wt. -%, preferably> 10 wt .-% to <35 wt .-%: and optionally the polyols (PO) in amounts of> 5 wt .-% to <20 wt .-%, preferably> 8 wt .-% to <15 wt .-%, based on the total weight of the solids in the dispersion, the amounts indicated add up to 100 wt .-%. The polyurethane resin used according to the invention is preferably prepared by reacting a polyacrylate copolymer (B) with at least one uretdione group-containing hardener (A) based on aliphatic, (cyclo) aliphatic, araliphatic and / or aromatic polyisocyanates which does not have any chemically bonded hydrophilizing Contains groups homogeneously mixed in a non-aqueous system. Subsequently, the carboxyl groups present in the polyacrylate copolymer (B) are preferably neutralized to at least 50%, more preferably 80% to 130%, particularly preferably 95 to 125% with suitable neutralizing agents and then dispersed with deionized water. The neutralization may be carried out before, during or after the dispersing step. However, preference is given to neutralization before the addition of water.

Suitable neutralizing agents are, for example, triethylamine, dimethylaminoethanol, dimethylcyclohexylamine, triethanolamine, methyldiethanolamine, diisopropanolamine, ethyldiisopropylamine, diisopropylcyclohexylamine, N-methylmorpholine, 2-amino-2-methyl-1-propanol, ammonia or other customary neutralizing agents or neutralization mixtures thereof.

Preference is given to tert. Amines such as e.g. Triethylamine, triethanolamine, diisopropylhexylamine, and dimethylethanolamine, particularly preferred are triethanolamine and dimethylethanolamine.

According to the present invention, the neutralizing agents are to be counted among the group of auxiliary additives (D).

As solvents under (C), all liquid substances are suitable which do not react with other ingredients. Preferred are acetone, methyl ethyl ketone, ethyl acetate, butyl acetate, xylene, heavy benzene, such as the commercially available Solvesso 100 and Solvesso 150, propyl englykolmono-n-butyleth er, dipropylene glycol dimethyl ether, methoxypropyl acetate, dibasic esters or mixtures thereof. Optionally, the solvent used can then be removed by distillation.

According to the invention in the paint or adhesive technology customary additives (D), such as leveling agents, for. As polysilicones or acrylates, light stabilizers, for. Example, sterically hindered amines, catalysts, for example, tin (II) 2-ethylhexyloctoate or dibutyltin dilaurate or other auxiliaries, as described, for. As described in EP 0 669 353, be contained in a total amount of preferably 0.05 to 5 wt .-%. Fillers and pigments such as titanium dioxide may be added in an amount of up to 50% by weight of the aqueous composition. Examples:

Raw materials used: Dowanol PnB: Propylene glycol mono-n-butyl ether from Dow

Peroxan DB: di-tert-butyl peroxide from Pergan.

Solvent Naphtha 100: an aromatic solvent, CAS: 64 742-95-6, from Azelis.

Veova 9: Versatic acid vinyl ester from the company Momentive. Used analytical methods:

All viscosity measurements were carried out with a Physica MCR 51 Rheometer from Anton Paar Germany GmbH (DE) according to DIN EN ISO 3219: 1994-10.

The NCO contents were determined titrimetrically in accordance with DIN EN ISO 11909: 2007-05.

The OH numbers were determined titrimetrically in accordance with DIN EN ISO 4629-2: 2015-02.

The determination of acid numbers is titrimetric according to DIN EN ISO 2114: 2002-06.

Solid content - Determination by means of convection oven according to DIN EN ISO 3251: 2008-06, method

B.

The determination of the average particle size (MTG) was carried out with a Zetasizer Nano from Malvem (DE) according to DIN ISO 13321: 2004-10.

The pH was determined using a pH meter according to DIN ISO 976: 2008-07 diluted 1: 4 with distilled water.

The residual monomer contents were measured according to DIN EN ISO 10283 gas chromatography with internal standard.

The pendulum hardness was measured on a standardized coil test panel (Coil Coating black - CS 200570, Heinz Zanders Prüf-Blech-Logistik) according to DIN EN ISO 1522: 2007-04 with a König pendulum. The chemical resistance was determined on a standardized coil test panel (Coil Coating black - CS 200570, Heinz Zanders Prüf-Blech-Logistik). A cotton swab soaked with the test substance (xylene or water) was placed on the paint surface and covered with a watch glass. After the specified exposure time, the cotton impregnated with the test substance was removed, the loaded area dried and immediately scrapped. Softening or discoloration of the paint surface was assessed. The assessment was carried out in accordance with DIN EN ISO 4628-1 as follows:

0 none, d. H. no visible damage

1 very few, d. H. small, just significant number of damages

2 few, d. H. small but significant number of damage

3 moderate damage

4 damage in considerable numbers

5 a lot of damage

Unless explicitly stated otherwise, all percentages are percentages by weight.

Preparation of a crosslinking agent containing retardation groups (renewer 1, preparation example)

1000 g (4.50 mol) of isophorone diisocyanate (IPDI) were admixed successively with 10 g (1%) of triisodecyl phosphite and 20 g (2%) of 4-dimethylaminopyridine (DMAP) as catalyst at room temperature under dry nitrogen with stirring. After 20 h, the reaction mixture, which had an NCO content of 28.7%, corresponding to a degree of oligomerization of 21.8%, without prior addition of a catalyst poison with the aid of a thin-film evaporator at a temperature of 160 ° C. and a pressure of 0, 3 mbar of volatile components.

This gave a pale yellow uretdione polyisocyanate having a content of free NCO groups of 17.0%, a content of monomeric IPDI of 0.4% and a viscosity of more than 200,000 mPas.

337 g of 1,4-butanediol, 108 g of 2-ethylhexanol and 569 g of e-caprolactone were mixed at room temperature under dry nitrogen, treated with 0.3 g of stannous octoate, stirred at 160 ° C for 5 h and then to room temperature cooled. To this mixture was then added 1850 g of the above-described uretdione group-containing polyisocyanate based on IPDI, heated to 80 ° C within 30 min. The reaction mixture was heated at a temperature of max. Stirred 100 ° C until the NCO content of the reaction mixture after 7 to 8 h has dropped to a value of 0.8%. To solidify the reaction mixture was poured onto a plate, crushed and then dissolved in Dowanol PnB, so that a solution with 60 wt .-% solids was formed. Examples 1 to 4

example 1

Table 1

Part 1 of Table 1 was weighed into a stirring apparatus under nitrogen and heated to 138 ° C. Thereafter, Part 2 was added uniformly at 138 ° C in 20 min. Subsequently, immediately part 3 and part 4 were added in parallel in 4 hrs. 30 Min. At 138 ° C evenly. After the addition, the reaction mixture was kept at 138 ° C for 30 min. Finally, Part 5 and Part 6 were added uniformly in 1 hr. 30 Min. At 138 ° C in parallel. After the addition, the reaction mixture was further held at 138 ° C for 1 hr. After cooling, a slightly yellowish, highly viscous polyacrylate solution was obtained. 500 g of this solution were weighed into a stirring apparatus under nitrogen and heated to 70 ° C. After homogenization, 567 g of the 60% crosslinker 1 solution in Dowanol PnB were added and the mixture became 30 again Min. Homogenized at 70 ° C, followed by addition of a mixture of 21.5 g of triethanolamine and 4.3 g Dimethylethanolainin. After stirring for a further 30 minutes at 70 ° C., 463 g of distilled water were stirred into the mixture. After fine adjustment of the viscosity to about 2000 mPas, a dispersion was obtained with the following characteristics:

Solids content 43.7% by weight

Acid number (100%) 13mg KOH / g

OH content (100%, calculated) 2.8% by weight

Average particle size 230 nm

Viscosity 2030 mPas

pH 7.5

The dispersion remained stable at 23 ° C for 10 months.

Example 2 500 g polyacrylate solution from Example 1 were weighed into a stirring apparatus under nitrogen and heated to 70.degree. After homogenization, 283 g of the 60% crosslinker 1 solution in Dowanol PnB were added and the mixture was rehomogenized for 30 min. At 70 ° C, followed by addition of a mixture of 21.5 g triethanolamine and 4.3 g dimethylethanolamine. After stirring for a further 30 minutes at 70 ° C., 407 g of distilled water were stirred into the mixture. After fine adjustment of the viscosity to about 2000 mPas, a dispersion was obtained with the following characteristics:

Solids content 41.7% by weight

Acid number (100%) 16.6 mg KOH / g

OH content (100%, calculated) 3.6% by weight

Average particle size 175 nm

Viscosity 2360 mPas

pH 7.5

The dispersion remained stable at 23 ° C for 10 months.

Example 3

Table 2

Part 1 of Table 2 was weighed into a stirring apparatus under nitrogen and heated to 138 ° C. Thereafter, Part 2 was added uniformly at 138 ° C in 20 min. Subsequently, immediately part 3 and part 4 were added in parallel in 4 hrs. 30 Min. At 138 ° C evenly. After the addition, the reaction mixture was kept at 138 ° C for 30 min. Finally, Part 5 and Part 6 were added uniformly in 1 hr. 30 Min. At 138 ° C in parallel. After the addition, the reaction mixture was further held at 138 ° C for 1 hr. After cooling to give a slightly yellowish, highly viscous polyacrylate solution at 100 ° C, the reaction mixture was bottled.

552 g of this solution were weighed into a stationary apparatus under nitrogen and heated to 70.degree. After homogenization, 471 g of the 60% crosslinker 1 solution in Dowanol PnB was added and the mixture was rehomogenized for 30 min at 70 ° C, followed by the addition of 14.6 g of dimethylethanolamine. After stirring for a further 30 minutes at 70 ° C., 466 g of distilled water were stirred into the mixture. After fine adjustment of the viscosity to about 2000 mPas, a stable dispersion was obtained with the following characteristics: Solids content 46.1% by weight

Acid number (100%) 16.3 mg KOH / g

OH content (100%, calculated) 2.1% by weight

Average particle size 225 nm

Viscosity 1110 mPas

pH 8.2

The dispersion remained stable for 5 months at 23 ° C.

Example 4

Table 3

Part 1 from Table 3 was weighed into a stationary apparatus under nitrogen and heated to 148 ° C. Thereafter, Part 2 was uniformly added at 148 ° C in 20 min. Subsequently, Part 3 and Part 4 were added in parallel at the same time in 6 hours at 148 ° C. After the addition, the reaction mixture was held at 148 ° C for 60 min. After cooling to 80 ° C, the polyacrylate solution was bottled. Table 4

Part 1 of Table 4 was weighed into a stirring apparatus under nitrogen and heated to 144 ° C. Thereafter, part 2 was uniformly added at 144 ° C in 20 min. Subsequently, Part 3 and Part 4 were immediately added in parallel in 4 hrs. 30 Min. At 144 ° C evenly. After the addition, the reaction mixture was held at 144 ° C for 5 min. Finally, Part 5 and Part 6 were added uniformly in 1 hour 30 min. At 144 ° C dosed. After the addition, the reaction mixture was again held at 144 ° C for 1 hr. After cooling, a slightly yellowish, highly viscous polyacrylate solution was obtained.

304 g of this solution were weighed into a stationary apparatus under nitrogen and heated to 70.degree. After homogenization, 385 g of the 60% crosslinker 1 solution in Dowanol PnB were added thereto and the mixture was again homogenized at 70 ° C. for 30 min, followed by the addition of 1 l of dimethylethanolamine. After a stirring time of 30 min. At 70 ° C were stirred into the mixture 324 g of distilled water. After fine adjustment of the viscosity to about 2000 mPas, a dispersion was obtained with the following characteristics:

Solids content 42.6% by weight

Acid value (100%) 18 mg KOH / g

OFI content (100%, calculated) 2.5% by weight

Average particle size 287 nm

Viscosity 2030 mPas

pH 8.7

The dispersion remained stable for 5 months at 23 ° C.

Paint tests:

Clearcoats from Examples 1 to 4 above were prepared (all weights in g): TABLE 5 Inventive Examples 5 to 8

The dispersions were homogenized in a speed mixer at 2000 rpm for 1 minute on a coil plate with a doctor blade with a layer thickness of 180 mih (wet). The plates with the applied wet paints were baked for 5 min at room temperature, for 30 min at 180 ° C and then stored for 24 hours at room temperature. The stored films were evaluated by application technology (Table 6).

Table 6. Paint Testing of Examples 5-8

As can be seen from Table 6, the uretdione-containing dispersions according to the invention give hard and stable coatings. From the uretdione-containing dispersions according to the invention, it is possible to produce both glossy and semi-gloss coatings h.

Claims

claims

1. Aqueous uretdione group-containing compositions comprising or consisting of

(B) at least one polyacrylate copolymer;

(C) optionally solvent; and

(D) optionally auxiliaries and additives;

wherein the quantitative ratio of the components (A) and (B) is such that the molar

Ratio of the present as uretdione NCO groups of the harder (A) to NCO-reactive groups of the polyacrylate copolymer (B) 3.0: 0.5 to 0.5: 3.0 and wherein A and B are present as a physical mixture.

2. Composition according to claim 1, characterized in that

the hardener A containing at least one uretdione group by reacting monomeric isocyanates comprising or consisting of at least one monomeric isocyanate selected from tetramethylene diisocyanate, cyclohexane-1,3- and 1,4-diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate (HDI), isocyanato-isocyanato 3,3,5-trimethyl-5-such as cyanoatomethyl cy clohexane (isophorone diisocyanate IPDI), dicyclohexylmethane 2,4'- and / or 4,4'-diisocyanate, tetramethylxylylene diisocyanate (TMXDI), Trii so cy anatononan, T oluylendiisocyanat (TDI), diphenylmethane-2,4'- and / or 4,4'-diisocyanate (MDI), T riphenylmethane-4,4'-diisocyanate or naphthylene-1, 5-diisocyanate or mixtures thereof was obtained.

3. Composition according to claim 1 or 2, characterized in that

as feedstocks for the at least one uretdione group-containing hardener A hydroxyl-containing monomers and / or polymers are used.

4. Composition according to one of the preceding claims, characterized in that the at least one uretdione group-containing hardener A has a free NCO content of less than 5 wt .-% and a content of uretdione groups from 1 to 18 wt .-% - calculated as C2N2O2, Molecular weight 84 g / mol - has.

5. Composition according to one of the preceding claims, characterized in that the aqueous composition has an acid number of 1 to 100 mg KOH / g.

6. The composition according to any one of the preceding claims, characterized in that the at least one polyacrylate copolymer is obtained by reacting a mixture of radically polymerizable monomers (M), comprising

(M2) Hydroxyl-functional, radically polymerizable monomers;

(M3) carboxyl-functional, free-radically polymerizable monomers;

(M4) optionally vinyl esters of aliphatic carboxylic acids;

7. Composition according to one of the preceding claims, characterized in that the at least one polyacrylate copolymer has an OH content greater than 1 wt .-% - calculated as OH group to fixed content, molecular weight 17 g / mol - and a number average molecular weight Mn of 500 to 20000 g / mol.

8. The composition according to any one of the preceding claims, characterized in that the solvent is selected from acetone, methyl ethyl ketone, ethyl acetate, butyl acetate, xylene, heavy benzene, propylene glycol mono-n-butyl ether, dipropylene glycol dimethyl ether, methoxypropyl acetate, dibasic esters or mixtures thereof.

9. The composition according to any one of the preceding claims, characterized in that the auxiliaries and additives are selected from V run agents, light stabilizers, catalysts, fillers and pigments or mixtures thereof.

10. The composition according to any one of the preceding claims, characterized in that the sum of the weight fractions of (A), (B) and (D) is 30 to 60 wt .-%, based on the solids content of the total aqueous composition.

11. A process for producing a polyurethane layer, comprising the steps

i) providing an aqueous uretdione group-containing composition according to any one of claims 1 to 10;

ii) applying the mixture obtained under i) to a substrate;

iii) drying the mixture from step ii), and

iv) curing the mixture from step iii) with heat from 40 ° C to 180 ° C for up to

180 minutes.

12. The method according to claim 11, characterized in that the aqueous uretdione group-containing composition was obtained by mixing the uretdione group-containing hardener A with the at least one polyacrylate copolymer B in the absence of water and subsequent dispersion with water.

13. Polyurethane layer, in particular polyurethane film, obtainable by a process according to claim 11 or 12.

14. A substrate which is coated or glued with the polyurethane chi cht according to claim 13.