EP3283540A1

EP3283540A1 - Aqueous polyurethane-polyacrylate dispersions

Info

Publication number: EP3283540A1
Application number: EP16719267.3A
Authority: EP
Inventors: Pantea Nazaran; Rolf Gertzmann; Tanja Hebestreit
Original assignee: Covestro Deutschland AG
Current assignee: Covestro Deutschland AG
Priority date: 2015-04-13
Filing date: 2016-04-12
Publication date: 2018-02-21
Also published as: WO2016166096A1; CN107428888B; CN107428888A; US20180118971A1

Abstract

The present invention relates to an aqueous polyurethane-polyacrylate dispersion, obtainable by radical polymerization of a component A), comprising an ethylenically unsaturated compound, at least in the presence of a component B), comprising water and a polyurethane resin, obtainable by reaction of the following synthesis components I), comprising at least one aliphatic, cycloaliphatic, araliphatic and/or aromatic compound having at least two or more isocyanate groups, II), comprising at least one polycarbonate polyol having an average molecular weight of 500 to 3000 g/mol, III), comprising at least one anionically hydrophilizing compound which has at least one OH- or NH-functional group and comprises a carboxyl and/or carboxylate group, IV), comprising at least one polyol and/or polyamine having an average molecular weight of between ≥ 62 and ≤ 500 g/mol, and optionally V), comprising at least one or more monoalcohols and/or monoamines, the radical polymerization being initiated using a hydrophilic initiator.

Description

Aqueous polyurethane-polyacrylate dispersions

The invention relates to an aqueous polyurethane-polyacrylate dispersion and a process for its preparation. Further objects of the invention are a coating composition containing the aqueous polyurethane-polyacrylate dispersion, and the use of this coating agent for producing a coating. Moreover, the invention relates to a composite of the coating and a substrate.

Aqueous polyurethane dispersions are suitable for the production of a variety of coatings and are characterized by very good properties, such as. Abrasion resistance, flexibility or toughness. In addition to the pure polyurethane dispersions and polyurethane-polymer hybrid dispersions, such as polyurethane-polyacrylate dispersions are known. Polyacrylate dispersions often have increased hardness and resistance to chemicals and weathering. In addition, a combination of polyurethane and polyacrylate dispersions may even provide synergistic effects. In general, the above-mentioned hybrid dispersions can be chemically and / or physically linked to one another. In this physical link, one can also speak of a physical blend.

As an example of chemically linked hybrid dispersions, WO 2011/089154 A1 discloses a process for the preparation of aqueous polyurethane-polyacrylate dispersions in which the polyurethane contains ethylenically unsaturated groups which are reacted with ethylenically unsaturated monomers. Via the crosslinking reaction of the unsaturated groups, chemically linked polymers are obtained.

The high complexity of the polymerization reaction is a disadvantage of the above-mentioned chemically linked hybrid dispersions. Furthermore, the chemical linkage increases the molecular weight and the viscosity of the products, which can also complicate the production.

In addition, not all polyurethane backbones are compatible with graft polymerization, so that the fields of application may be limited here.

In contrast, the polymerization reaction in a physical blend to prepare the hybrid dispersions is much easier to control and does not suffer from the disadvantages described above.

Polyurethane-polyacrylate hybrid systems in which the polyurethane and the polyacrylate do not chemically bond with each other but interact only physically, are disclosed for example in EP 1124871 Bl. The described polyurefhan-polyacrylate hybrid dispersion is prepared by a pre-emulsified mixture of monomer and lipophilic (oil-soluble) initiator in the presence of a polyurethane.

Due to the lipophilic initiators, the radical polymerization takes place in this method in the monomer droplets. For certain polymer compositions, however, this method of preparation is not suitable, for example when very hydrophobic acrylate monomers which are not sufficiently soluble in water are used, or when the monomer mixture and / or initiator solution are to be dosed to produce certain polymer morphologies, e.g. To achieve hybrid dispersions with a core-shell morphology of the polymer particles. In such cases, the dispersions prepared by the method described in EP 1124871 Bl have insufficient stability or can not be prepared at all due to the use of a lipophilic initiator in the absence of an additional emulsifier.

The aqueous polyurethane dispersions described at the outset are already used, for example, for coatings in the automotive sector. By avoiding organic solvents even stricter environmental regulations can be met. To make the painting process more efficient, for example, less paint layers can be applied or the thickness of the paint layers can be reduced.

On the other hand, these efficiency increases also increase the demands on the properties of the coating systems used and thus, above all, of the aqueous dispersions used. Particularly important here are good hiding power, hardness, chemical and weather resistance and a good flip-flop effect. This results in an application for hybrid dispersions, such as polyurethane-polyacrylate dispersions, since a targeted modification with polyacrylates makes the desired properties feasible. In addition to the properties of the coatings obtainable from the dispersions, the highest possible stability of the dispersion or of the binder to shear forces during application or during pumping operations is very important. However, the prior art polyurethane-polyacrylate dispersions have insufficient stability and can not be formulated into binders having the required properties. Therefore, it was an object of the present invention to overcome at least one disadvantage of the prior art at least in part.

Furthermore, it was an object of the present invention to provide an aqueous polyurethane-polyacrylate dispersion which would become binders having improved stability to shear forces over the polyurethane-polyacrylate known in the art. Dispersions leads and from which also coatings with a very good opacity, hardness, chemical and weather resistance and a good flip-flop effect can be produced.

A further object of the present invention was to provide a solvent-free and emulsifier-free aqueous polyurethane-polyacrylate dispersion having the same properties as described above.

This object is achieved according to the invention by an aqueous polyurethane-polyacrylate dispersion obtainable by free-radical polymerization of a component A) comprising an ethylenically unsaturated compound, at least in the presence of a component B) comprising water and a polyurethane resin obtainable by reacting the following structural components I) comprising at least one aliphatic, cycloaliphatic, araliphatic and / or aromatic compound having at least two or more isocyanate groups,

Π) comprising at least one polycarbonate polyol having an average molecular weight of 500 to 3000 g / mol,

III) comprising at least one anionic hydrophilic compound having at least one OH or NH functional group and a carboxyl and / or

Contains carboxylate group,

IV) comprising at least one polyol and / or polyamine having a middle one

Molecular weight between> 62 and <500 g / mol and optionally

V), comprising at least one or more monoalcohols and / or monoamines, wherein a hydrophilic initiator is used as initiator of the radical polymerization, dissolved.

In the present context, a hydrophilic initiator is understood as meaning a chemical compound which has a high affinity for water or a high tendency to solvate in water and acts as a radical initiator.

In the present case, the stability to shear forces of the polyurethane-polyacrylate dispersions according to the invention is also referred to as ring-line stability. The loop stability can be simulated, for example, by means of a Göttfert capillary rheometer, as in K. Georgieva, DJ. Dijkstra, H. Fricke, N. Willenbacher, /. Colloid Interface Be. 2010, 352, 265-277. In Figure 1 and Table 1 on page 267 of K. Georgieva et al. are shown the apparatus and technical specifications used for the present application. For the test, a certain amount of the binder to be examined is placed in the container provided for this purpose and by means of a movable cylinder at a constant speed an annular gap of 20 μιη gap size pressed. The greater the shear stability of the binder, the smaller the pressure build-up when pressing through the annular gap. With non-shear stable material, the binder coagulates, clogging the nozzle and pressure build-up is detected. The simulated shear forces can be calculated from the gap size and the speed. In general, the mass ratio of the components A) and B) can be freely selected over a wide range. In a first preferred embodiment, the component A) in 3 to 40 wt .-%, preferably in 5 to 30 wt .-% and particularly preferably in 7 to 25 wt .-%, the component B) in 97 to 60 wt. %, preferably in 95 to 70 wt .-% and particularly preferably in 93 to 75 wt .-%, based on the total amount of the polyurethane-polyacrylate dispersion, used wherein the proportions are normalized so that they also with optional use of additional Components C) can not be greater than 100% and particularly preferably complement each other to 100%.

The initiation of the polymerization takes place with the customary for free radical polymerization hydrophilic initiators. These include water-soluble inorganic persulfates, such as ammonium or sodium persulfate.

According to a further preferred embodiment, the hydrophilic initiator comprises one or more persulfate-containing compounds, is preferably exclusively one or more persulfate-containing compounds and is particularly preferably exclusively ammonium peroxodisulfate, sodium peroxodisulfate and / or potassium peroxodisulfate. Component A)

In a further preferred embodiment, component A) comprises at least one aliphatic, cycloaliphatic or aromatic acrylate or methacrylate which is substituted or unsubstituted, preferably at least one aliphatic or cycloaliphatic, optionally alkyl-substituted acrylate or methacrylate and particularly preferably at least one mixture of an aliphatic, optionally alkyl substituted acrylate and an aliphatic, optionally alkyl substituted methacrylate.

Suitable ethylenically unsaturated compounds for component A) are one or more of the following compounds:

VI), styrene and / or other vinylaromatic compounds, VII), acrylic esters,

VIII), polyvinylidene compound of a functionality ^ 2, IX), methacrylic acid ester.

Vinylaromatic compounds VI), in particular having up to 20 carbon atoms, are, for example, styrene, vinyltoluene, o- and p-methylstyrene, butylstyrene, decylstyrene, halogenated styrenes, for example monochlorostyrenes, dichlorostyrenes, tribromostyrenes or tetrabromostyrenes. Preference is given to styrene.

Suitable acrylic esters VII) include, in particular, methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, n-butyl acrylate, sec-butyl acrylate, tert-butyl acrylate, pentyl acrylate, hexyl acrylate, heptyl acrylate, octyl acrylate, 2-octyl acrylate, ethylhexyl acrylate, nonyl acrylate, 2-methyl octyl acrylate, 2- (tert-butyl) heptyl acrylate, 3- (iso-propyl) heptyl acrylate, decyl acrylate, undecyl acrylate, 5-methylundecyl acrylate, dodecyl acrylate, 2-methyldodecyl acrylate, tridecyl acrylate, 5-methyltridecyl acrylate, tetradecyl acrylate, pentadecyl acrylate, hexadecyl acrylate, 2-methylhexadecyl acrylate, Heptadecyl acrylate, 5- (iso -propyl) heptadecyl acrylate, 5-ethyloctadecyl acrylate, octadecyl acrylate, nona-decyl acrylate, eicosyl acrylate, cycloalkyl acrylates such as cyclopentyl acrylate, cyclohexyl acrylate, 3-vinyl-2-butylcyclohexyl acrylate, cycloheptyl acrylate, cyclooctyl acrylate, bornyl acrylate, tetrahydrofurfuryl acrylate and isobornyl acrylate. Preference is given to ethyl acrylate, n-butyl acrylate, ethylhexyl acrylate, cyclohexyl acrylate, particular preference to ethylhexyl acrylate.

Suitable polyvinylidene compounds VIII) include those compounds which have at least two olefinically unsaturated bonds. These include, in particular, acrylic or methacrylic acid esters of polyols of functionality> 2, e.g. Ethylene glycol diacrylate, diethylene glycol diacrylate, glycerol diacrylate, glycerol triacrylate, ethylene glycol dimethacrylate, 1,3-propanediol diacrylate, 1,3-propanediol dimethacrylate, 1,4-butanediol diacrylate, 1,4-

Butanediol dimethacrylate, 1,6-hexanediol diacrylate, 1,6-hexanediol dimethacrylate, 1,2,4-butanetriol trimethacrylate, 1,4-cyclohexanediol diacrylate, 1,4-benzenediol dimethacrylate, pentaerythritol tri- and tetraacrylate or methacrylate, dipentaerythritol hexaacrylate, tripentaerythritol hexaacrylate, tripentaerythritol octacrylate, trimethylolpropane triacrylate , Trimethylolpropane trimethacrylate, trimethylolethane triacrylate, sorbitol hexaacrylate, 1,3-propanediol diacrylate, 1,5-pentadimoldimethacrylate, 1,9-nonanediol dimethacrylate, 1,10-decanediol dimethacrylate, propylene glycol diacrylate, dipropylene glycol diacrylate, diacrylates and dimethacrylates of polyethylene glycol having a molecular weight of 200 to 1500 g / mol. Preference is given to 1,4-butanediol diacrylate, trimethylolpropane dimethacrylate, ethylene glycol dimethacrylate, 1,6-hexanediol dimethacrylate, particularly preferably ethylene glycol dimethacrylate or 1,6-hexanediol dimethacrylate.

Suitable esters IX) of methacrylic acid include in particular methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, sec- Butylmethacrylate, tert-butylmethacrylate, pentylmethacrylate, hexylmethacrylate, heptylmethacrylate, octylmethacrylate, 2-octylmethacrylate, ethylhexylmethacrylate, nonylmethacrylate, 2-methyloctylmethacrylate, 2- (tert-butyl) heptylmethacrylate, 3- (iso-propyl) heptylmethacrylate, decylmethacrylate, undecylmethacrylate, 5- Methylundecylmethacrylat, dodecyl methacrylate, 2- Methyldodecylmethacrylat, tridecyl, 5-Methyltridecylmethacrylat, Tetradecylmeth- acrylate, pentadecyl, hexadecyl, 2-Methylhexadecylmethacrylat, heptadecyl, 5- (iso-propyl) heptadecyl, 5-Ethyloctadecylmethacrylat, octadecyl methacrylate, nonadecyl methacrylate, eicosyl methacrylate, cycloalkyl methacrylates, such as for example, cyclopentyl methacrylate, cyclohexyl methacrylate, 3-vinyl-2-butylcyclohexyl methacrylate, cycloheptyl methacrylate, cyclooctyl methacrylate, bornyl methacrylate, tetrahydrofurfuryl methacrylate or isobornyl methacrylate. Weitherin the methacrylic acid derivatives can also be used in the form of the corresponding nitriles or amides, such as methacrylonitrile or methacrylamide. In addition, it is possible to use other functional monomers depending on the desired application, such as diacetone methacrylamide or acetoacetoxyethyl methacrylate. Preferred are methyl methacrylate, ethyl methacrylate, butyl methacrylate, tert-butyl methacrylate, particularly preferred are methyl methacrylate, tert-butyl methacrylate or butyl methacrylate.

Polyurethane resin of component B)

Construction component I): Suitable aliphatic, cycloaliphatic, araliphatic and / or aromatic compounds having at least two or more isocyanate groups are, for example, di- or triisocyanates of the molecular weight range 140 to 400. Preferred diisocyanates are 1,4-diisocyanatobutane, 1,5-diisocyanatopentane (PDF), 1,6-diisocyanatohexane (HDI), 1,5-diisocyanato-2,2-dimethylpentane, 2,2,4- and 2,4 respectively , 4-trimethyl-l, 6-diisocyanatohexane, 1,10-diisocyanatodecane, 1,3- and 1,4-diisocyanatocyclohexane, 1,4-diisocyanato-3,3,5-trimethylcyclohexane, 1,3-diisocyanato-2-one methylcyclohexane, 1,3-diisocyanato-4-methylcyclohexane, 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (isophorone diisocyanate, IPDI), 1-isocyanato-1-methyl-4 (3) isocyanatomethylcyclohexane, 2,4'- and 4,4'-diisocyanatodicyclohexylmethane (H12-MDI), 1,3- and 1,4-bis (isocyanatomethyl) cyclohexane, 4,4'-diisocyanato-3,3'-dimethyldicyclohexylmethane , 4,4'-diisocyanato-3,3 ', 5,5'-tetramethyl-dicyclohexylmethane, 4,4'-diisocyanato-1, 1'-bi (cyclohexyl), 4,4'-diisocyanato-3,3' -dimethyl-1, l '-bi (cyclohexyl), 4,4'-diisocyanato-2,2', 5,5'-tetra-methyl-1, l '-bi (cyclohexyl), 1,8- Diisocyanato-p-menthane, 1,3-diisocyanato-adamantane, 1,3-dimethyl-5,7-diisocyanatoadamant 1,3- and 1,4-bis (isocyanatoethyl) benzene (XDI), 1,3- and 1,4-bis (1-isocyanato-1-methylethyl) benzene (TMXDI), bis ( 4- (1-isocyanato-1-methylethyl) phenyl) carbonate, 1,3- and 1,4-phenylene diisocyanate, 2,4- and 2,6-toluene diisocyanate (TDI) and any desired mixtures of these isomers, diphenylmethane-2, 4 ' and / or 4,4'-diisocyanate (MDI) and naphthylene-1,5-diisocyanate (NDI). Other likewise suitable diisocyanates can be found, for example, in Justus Liebigs Annalen der Chemie, Volume 562 (1949) pp. 75-136.

In a further particularly preferred embodiment, the synthesis component I) comprises at least one aliphatic, cycloaliphatic, aliphatic and / or aromatic diisocyanate, preferably a mixture of aliphatic and / or cycloahphatic diisocyanates and particularly preferably a mixture of 1,6-diisocyanatohexane, 1-isocyanate 3,3,5-trimethyl-5-isocyanatomethylcyclohexane and / or 4,4'-diisocyanato-dicyclohexylmethane.

The preparation of the above diisocyanates can be prepared by known methods, for. B. by phosgenation or phosgene-free way, for example, by urethane cleavage done. It is also possible to use proportionately up to 5% by weight, based on the polyurethane solid resin, of trihydric and / or higher isocyanates, in order thus to ensure a certain degree of branching or crosslinking of the polyurethane. Such isocyanates are e.g. are obtained by reacting divalent isocyanates with each other such that a part of their isocyanate groups are derivatized to isocyanurate, biuret, allophanate, uretdione or carbodiimide groups. Such polyisocyanates hydrophilized via ionic groups are also suitable. Such polyisocyanates may have high functionality, e.g. of more than 3.

Building component II):

The synthesis component II) comprises at least one polycarbonate polyol having an average molecular weight of 500 to 3000 g / mol. In a further preferred embodiment, the polycarbonate polyol has an average molecular weight of from 1000 to 3000 g / mol, preferably from 1250 to 2500 g / mol and more preferably from 1500 to 2100 g / mol. The average molecular weight of the polycarbonate polyol can be determined by GPC (gel permeation chromatography) according to DIN 55672-1. The selected polycarbonate polyols can have an OH functionality of from 1.8 to 5, preferably from 1.9 to 3 and particularly preferably from 1.9 to 2.0, and can be prepared by known processes.

Suitable polycarbonates are obtainable, for example, by reacting diphenyl carbonate, dimethyl carbonate or phosgene with polyols, preferably diols. Examples of suitable diols are ethylene glycol, 1,2- and 1,3-propanediol, 1,3- and 1,4-butanediol, 1,6-hexanediol, 1,8-octanediol, neopentyl glycol, 1,4-bis-hydroxymethyl-cyclohexane , 2-methyl-l, 3-propanediol, 2,2,4-trimethylpentane-1,3-diol, dipropylene glycol, polypropylene glycol, dibutylene glycol, polybutylene glycol, bisphenol A, tetrabromobisphenol A but also lactone-modified diols can be used. Preferred is when the diol 40 to 100 wt .-% of hexanediol, preferably 1,6-hexanediol and / or hexanediol derivatives, particularly preferably those which in addition to terminal OH groups ether or ester groups, for example products which by reacting 1 mol of 1,6-hexanediol with at least 1 mole, preferably 1 to 2 moles of caprolactone or by Etherification of 1,6-hexanediol with itself to di- or Trihexylenglykol were obtained contains. The polyether-polycarbonate diols described in DE-A 37 17 060 can also be used. Preferably, the polycarbonate polyols are linear. However, they may optionally be easily branched by the incorporation of polyfunctional components, especially low molecular weight polyols. For example, glycerol, trimethylolpropane, hexanetriol-1,2,6, butanetriol-1,2,4, trimethylolethane, pentaerythritol, quinitol, mannitol and sorbitol, methyl glycoside or 1,3,3,6-dianhydrohexitols are suitable for this purpose.

In addition to the polycarbonate polyols essential to the invention, it is also possible to use e.g. Polyester, polyethers, polyacetals, polyolefins, polyacrylates and polysiloxanes are used. Polyester and / or polyethers are preferably used as further polyol component.

In addition to the polycarbonate polyols essential to the invention, preference is given to using little to no further polyol components, as described above. Component B) preferably contains the further polyol component at less than 10% by weight, or preferably at less than 5% by weight, or preferably at less than 3% by weight, or preferably at less than 1% by weight. , or preferably in a range of 0.001 to 10 wt .-%, or preferably in a range of 0.001 to 5 wt .-%, or preferably in a range of 0.002 to 3 wt .-%, or preferably in a range of 0.003 to 1 wt .-%, each based on the total amount of component B). Component B) preferably contains polyester polyol and / or polyether polyol as further polyol component to less than 10% by weight, or preferably to less than 5% by weight, or preferably to less than 3% by weight, or preferably to less than 1 wt%, or preferably in a range of 0 to 10 wt%, or preferably in a range of 0.001 to 5 wt%, or preferably in a range of 0.002 to 3 wt%, or preferably in a range of 0.003 to 1 wt .-%, each based on the total amount of component B). The structural component I) preferably contains no polyether polyol and / or polyester polyol. Preferably, component B) has no polyether polyol and / or polyester polyol.

Construction component III): The synthesis component III) comprises at least one anionically hydrophilicizing compound which has at least one OH or NH-functional group and contains a carboxyl and / or carboxylate group. According to a further preferred embodiment, the anionically hydrophilizing compound is free of sulfonic acid groups and sulfonate groups, preferably comprises dimethylolpropionic acid, dimethylolpropionate, N- (2-aminoethyl) -2-aminoethane carboxylic acid and / or N- (2-aminoethyl) -2-aminoethanoate and particularly preferably consists of dimethylolpropionic acid, dimethylolpropionate, N- (2-aminoethyl) -2-aminoethanecarboxylic acid and / or N- (2-aminoethyl) -2-aminoethanoate.

Building component IV): The structural component IV) comprises at least one polyol and / or polyamine having an average molecular weight between> 62 and <500 g / mol, preferably between> 62 to <400 g / mol and more preferably between> 90 to <300 g / mol. The following compounds are suitable here, for example: ethanediol, 1,2- and 1,3-propanediol, 1,2-, 1,3- and 1,4-butanediol, 1,5-pentanediol, 3-methyl-pentanediol-1, 5, 1,6-hexanediol, neopentyl glycol, cyclohexane-1,4-dimethanol, 1,2- and 1,4-cyclohexanediol, 2-ethyl-3-propyl-pentanediol, 2,4-dimethyl-pentanediol, 2-ethyl-2 Butylpropandiol, diethylenetriamine, ethylenediamine, ether oxygen-containing diols, such as Diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, polyethylene, polypropylene or polybutylene glycols, N-substituted ethanolamines and mixtures of these products. Preferred polyols are 1,4-butanediol, 1,5-pentanediol, 3-methylpentanediol-1,5, 1,6-hexanediol, neopentyl glycol, cyclohexane-1,4-dimethanol, 1,2- and 1,4- Cyclohexanediol and N-substituted ethanolamines. Very particularly preferred polyols and / or polyamines are 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, diethylenetriamine, ethylenediamine, and N-substituted ethanolamines.

Tri- and higher-functional alcohols of the stated molecular weight range can be used proportionally in an amount, so that the polymer solution remains stirrable. Such components include, for example, trimethylolpropane, glycerol, and pentaerythritol.

Building component V):

The optional component V) comprises at least one or more monoalcohols and / or monoamines. In general, these compounds can have 1 to 18 C atoms. Suitable monoalcohols or monoamines are, for example, ethanol, 1-propanol, 2-

Propanol, primary butanol, secondary butanol, n-hexanol and isomers thereof, 2-ethylhexyl alcohol, ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, tripropylene glycol monomethyl ether, dipropylene glycol monopropyl ether, propylene glycol monobutyl ether, dipropylene glycol monobutyl ether, tripropylene glycol monobutyl ether, 1 -Octanol, 1-dodecanol, 1-hexadecanol, lauryl alcohol and stearyl alcohol and butylamine, propylamine, aminoethanol, aminopropanol, diethanolamine or dibutylamine. Preference is given to ethanol, n-butanol, ethylene glycol monobutyl ether, 2-ethylhexanol, 1-octanol, 1-dodecanol, 1-hexadecanol, butylamine, propylamine, aminoethanol, dimethylethanolamine, Aminopropanol, diethanolamine or dibutylamine used. Particularly preferred are n-butanol and ethylene glycol monobutyl ether.

Preparation of component B)

Component B) comprises a polyurethane resin and water. The polyurethane resin is obtainable by a process in which the synthesis components II), III), IV) and optionally V) are separated and reacted in any order or as a mixture with the synthesis component I) and the synthesis component III) before, during or after Transfer of the polyurethane resin, which is preferably present at 99 to 65 wt .-%, more preferably 95 to 70 wt .-%, most preferably 90 to 80 wt .-% dissolved in a suitable solvent, neutralized and the polyurethane resin is dispersed in water , Ideally, the synthesis component V) is added only if the reactivity toward isocyanate groups is moderate and thus does not lead to gelling of the batch. In this case, both the synthesis component I) and one or more of the components II) -V) can be submitted. Preference is given to component I), the components II) -V) are metered in and reacted with component I).

Preferably, the component B) after the reaction of the structural components I) to V) no aliphatic C-C double bonds.

In general, the synthesis components I) to V) can be used to prepare the polyurethane resin in any proportions. However, it is hereby preferred that the synthesis components I) to V) in proportions of

From 10 to 45% by weight, preferably from 20 to 35% by weight, of the structural component I),

45 to 75 wt .-%, preferably 55 to 70 wt .-% of the synthesis component II),

0.1 to 15 wt .-%, preferably 3 to 10 wt .-% of the structural component III),

0.1 to 5 wt .-%, preferably 0.5 to 3 wt .-% of the structural component IV) and 0 to 5 wt .-%, preferably 0 to 3 wt .-% of the structural component V), based on the total solids content the polyurethane resin are used and the proportions are chosen so that they can not be greater than 100%, and particularly preferably to 100% complement.

As the solvent easily volatile components are used with boiling points below 100 ° C, which are later removed by distillation from the dispersion. Suitable solvents For example, acetone, methyl ethyl ketone, tetrahydrofuran and tert-butyl methyl ether, acetone is preferred.

"Solvent-free" in the sense of the present application means that maximum solvent amounts of <0.9 wt .-%, preferably <0.5 wt .-%, more preferably <0.3 wt .-% may remain in the dispersion.

Suitable neutralizing agents are alkaline organic and / or alkaline inorganic compounds. Preferred are, in addition to aqueous ammonia, ethylamine and dimethylamine solutions, volatile primary, secondary and tertiary amines, e.g. Dimethylethanolamine, morpholine, N-methylmorpholine, piperidine, diethanolamine, triethanolamine, diisopropylamine, 2-amino-2-methylpropanol and 2-N, N-dimethylamino-2-methylpropanol or mixtures of these compounds. Particularly preferred are unreactive towards isocyanates tertiary amines such. Triethylamine, diisopropylethylamine and N-methylmorpholine and mixtures of these tertiary amines, which are preferably added to the prepolymer prior to dispersion.

Depending on the degree of neutralization, the dispersion can be adjusted very finely divided, so that it has practically the appearance of a solution. The solids content of the dispersion obtained after distillation of the solvent can be varied within wide limits, for example from 20 to 65 wt .-%. A preferred solids range here ranges from 30 to 50% by weight and particularly preferred is a solids content of 33 to 45% by weight.

Excess isocyanate groups are then reacted in the aqueous phase with the synthesis component IV).

In addition to the water used to disperse the polyurethane resin, component B) may contain additional water.

Optional component C)

In addition to the components A), B) essential to the invention and the hydrophilic initiator, in a further preferred embodiment the polyurethane-polyacrylate dispersion according to the invention may also contain an optional component C). The optional component C) may comprise, for example, further polymers such as polyacrylate dispersions or polyurethane dispersions.

Preferably, the polyurethane-polyacrylate dispersion has no further component C) in addition to the components A) and B).

In a preferred embodiment of the aqueous polyurethane-polyacrylate dispersion, the following structural components exist I), of at least one aliphatic, cycloaliphatic, aliphatic and / or aromatic compound having at least two or more isocyanate groups,

II), from at least one polycarbonate polyol having an average molecular weight of 500 to 3000 g / mol,

III), from at least one anionic hydrophilicizing compound which has at least one OH or NH-functional group and contains a carboxyl and / or carboxylate group,

IV), from at least one polyol and / or polyamine having an average molecular weight between> 62 and <500 g / mol. In a preferred embodiment of the aqueous polyurethane-polyacrylate dispersion, component B) comprises a polyester polyol and / or a polyether polyol as further polyol component together to less than 10 wt .-%, preferably less than 5 wt .-%, or preferably less as 3 wt .-%, based on the total weight of component B). Preparation of the aqueous polyurethane-polyacrylate dispersion according to the invention

A process for the preparation of the aqueous polyurethane-polyacrylate dispersion according to the invention is a further subject of the present invention. In this process, the radical polymerization of component A) is carried out in the presence of at least the hydrophilic initiator and component B). Preferably, no other initiator except a hydrophilic initiator is used.

In the process according to the invention, it is preferred if component B) is initially charged and the free-radical polymerization is metered in by metering component A) in the presence of at least the hydrophilic initiator, which preferably also continuously in parallel with the metered addition of component A) to the component B) introduced will be performed. The metered addition may be carried out batchwise or continuously, preference being given here to continuous metered addition. The continuous metering can be carried out over any period, which is selectable depending on the quantities to be used. The choice of the appropriate period can also be used specifically to control the morphology of the polyurethane-polyacrylate dispersion according to the invention, since the forming polyacrylate oligomers are oriented in the polyurethane particles and thus the structure of the core-shell morphology can be influenced.

Optionally, in addition to the water used to disperse the polyurethane, further solvent, preferably water, may be added to the component B) before the reaction with the component A) takes place. As already described above, in another preferred embodiment of the process according to the invention, the hydrophilic initiator is likewise metered in continuously to component B) in parallel with the continuous metered addition of component A) to component B). In general, the hydrophilic initiator may be added dissolved in bulk or in a suitable solvent. In this case, it is preferred if the initiator is metered in dissolved in a solvent. Very particular preference is given to using water as the solvent. In general, the initiator concentration can be freely selected over a wide range, but the concentration of the hydrophilic initiator in the selected solvent is preferably in a range of> 0.001 to <5 wt .-%, preferably from> 0.01 to <3 wt. -% and particularly preferably from> 0.1 to <2 wt .-%.

In principle, it is possible that component A) can be added in its total amount to be used in one step or in several portions. However, it has been found to be particularly preferred if a portion of component A) is added in parallel with a portion of the optionally dissolved, hydrophilic initiator in a first step to the component B) and the resulting mixture then up to 5 hours, preferably until is stirred for 3 hours and more preferably up to one hour, before the remaining component A) is added in parallel with the remaining, optionally dissolved, hydrophilic initiator to the stirred mixture. The addition within the portions is preferably carried out continuously. After complete addition of component A) and the hydrophilic initiator, the mixture obtained can be stirred for a certain time, preferably up to 5 hours and more preferably up to 3 hours.

The radical polymerization of component A) in the presence of at least the hydrophilic initiator and component B) may preferably be carried out at temperatures between> 30 ° C and <95 ° C. It is irrelevant whether component B) is heated before or during the addition of component A) and the initiator. However, it is particularly preferred if the temperature is between> 40 ° C and <90 ° C. This results in the advantage that the reaction rate can be increased without the risk of destabilization of the polyurethane dispersion. In a further preferred embodiment of the process according to the invention, the free radical polymerization of component A) takes place in the presence of a hydrophilic initiator and component B) in the absence of additional emulsifiers.

If necessary, the resulting polyurethane-polyacrylate dispersion of the invention can also be filtered. In a further preferred embodiment, the polyurefan polyacrylate dispersion according to the invention has a solids content of from 20 to 70% by weight, preferably from 30 to 60% by weight and particularly preferably from 40 to 50% by weight. The polyurethane-polyacrylate dispersion according to the invention is particularly preferably solvent-free in the sense of the present invention.

The aqueous polyurethane-polyacrylate dispersion according to the invention is suitable for a large number of applications, for example as a binder component in a coating composition. Due to the very low proportion of solvents which may be present, other than water, the dispersion according to the invention has particularly advantageous environmental properties.

Another object of the invention are therefore coating compositions comprising at least one inventive polyurethane-polyacrylate dispersion and at least one crosslinking agent and optionally further auxiliaries and additives.

Examples of crosslinking agents are amide and amine-formaldehyde resins, phenol resins, aldehyde and ketone resins, for example phenol-formaldehyde resins, resols, furan resins, urea resins, carbamic acid ester resins, triazine resins, melamine resins, benzoguanamine resins, cyanamide resins, aniline resins, water-dilutable or water-dispersible melamine or urea - Formaldehyde condensation products suitable. Preferably, amino crosslinker resins are used. Also suitable crosslinking agents may also be blocked polyisocyanates, for example based on 1,6-hexamethylene diisocyanate, bis (4-isocyanatocyclohexane) methane, 1,3-diisocyanatobenzene, tetramethylene diisocyanate, methyl pentamethylene diisocyanate, dodecamethylene diisocyanate, 1,4-diisocyanato-cyclohexane, 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane, 4,4'-diisocyanato-dicyclohexylmethane, 4,4'-diisocyanato-dicyclohexylpropane (2,2), 1,4-diisocyanato isocyanatobenzene, 1-methyl-2,4 (2,6) -diisocyanatocyclohexane, 2,4-diisocyanatotoluene, 2,6-diisocyanato-toluene, 4,4'-diisocyanato-diphenylmethane, 2,2'- and 2, 4'-diisocyanato-diphenylmethane, p-xylylene diisocyanate, p-isopropylidene diisocyanate, 4-isocyanatomethyl-l, 8-octane diisocyanate, p-xylylene diisocyanate and α, α, α ', α'-tetramethyl-m- or p-xylylene diisocyanate, and from these existing mixtures. It is of course also possible on the basis of the exemplified polyisocyanates in polyurethane chemistry known per se higher functional polyisocyanates with uretdione groups and / or carbodiimide and / or allophanate and / or isocyanurate and / or urethane groups and / or iminooxadiazinedione groups and / or oxadiazinetrione groups and / or Use biuret groups as blocked crosslinking agents. It is also possible to use mixtures of different diisocyanates and / or polyisocyanates.

Suitable blocking agents for the aforementioned polyisocyanates may include monoalcohols, e.g. Methanol, ethanol, butanol, hexanol, benzyl alcohol, oximes, e.g. Acetoxime, methyl ethyl ketoxime, lactams, e.g. Caprolactam, phenols, CH-acidic compounds such as e.g. Acetoacetic ester or malonic acid ester, e.g. Diethyl malonate, dimethylpyrazole, amines such as e.g. tert-butylbenzylamine, triazole, dimethyltriazole, dicyclohexylamine or diisopropylamine.

The optional auxiliaries and additives may be, for example, cobinders known to those skilled in the art, drying agents, fillers, cosolvents, colorants or effect pigments, leveling agents, thickeners or matting agents. Optionally, compounds which have reactive groups relative to the crosslinking agent can also be used as auxiliaries and additives.

The coating compositions according to the invention can be used very well to produce a coating on a substrate. Such use is therefore a further object of the invention.

An application of the coating composition according to the invention can take place by known methods, for example by spraying, brushing, flooding or by means of rollers or doctor blades on any substrates. Especially in the application, the high stability of the coating composition to shear forces through the inventive aqueous polyurethane-polyacrylate dispersion.

Suitable substrates are, for example, metal, wood, glass, stone, ceramic materials, concrete, plastics, composites, textiles, leather or paper, which may optionally be provided with conventional primers prior to coating. Particularly preferred substrates are substrates which have a surface of metal and / or plastic, also in the form of films.

The respective drying conditions to be used can be adapted to the crosslinking agents used and, if appropriate, auxiliary agents and additives used.

After drying the coating composition according to the invention on the substrate, a coating is obtained which is characterized by very good mechanical and optical properties. Furthermore, the coatings of the invention are characterized by a high hiding power. A coating obtainable by using the coating composition according to the invention is therefore a further subject of the invention.

In addition to the coating itself, another object of the invention is a composite of a coating according to the invention and a substrate having a surface made of metal and / or plastic.

The invention will be explained in more detail by way of examples.

Examples

Unless otherwise indicated, all percentages are by weight.

Unless otherwise stated, all analytical measurements are based on temperatures of 23 ° C. The solids contents (non-volatile content) were determined according to DIN-EN ISO 3251.

NCO contents were determined volumetrically in accordance with DIN-EN ISO 11909, unless expressly stated otherwise.

The control of free NCO groups was carried out by means of IR spectroscopy (band at 2260 cm ^-1 ) The indicated viscosities were determined by means of rotational viscometry according to DIN 53019 at 23 ° C. using a rotational viscometer from Anton Paar Germany GmbH, Ostfildern, DE.

The mean particle sizes were determined by means of laser correlation spectroscopy (LKS) using a Malvern Zetasizer 1000 spectrometer from Malvern Instruments Ltd., with given Z average values. The number average molecular weight was determined by gel permeation chromatography (GPC) in tetrahydrofuran at 23 ° C. The procedure is according to DIN 55672-1: "Gel permeation chromatography, Part 1 - tetrahydrofuran as eluent" (SECurity GPC system from PSS Polymer Service, flow rate 1.0 ml / min, columns: 2xPSS SDV linear M, 8 × 300 mm, 5 μmol RID detector). This polystyrene samples of known molecular weight are used for calibration. The calculation of the number average molecular weight is software-based. Baseline points and evaluation limits are defined in accordance with DIN 55672 Part 1.

Evaluation of the paint film

pour-on test

The binder mixture was poured over a cleaned glass plate which was stored vertically / slightly obliquely for 2 hours at room temperature. This was followed by a visual

Scanning against a light source and a dark background to assess inclusions (e.g., specks, gel particles, bubbles) or perturbations (e.g., haze, cracking, flow disturbance) in the paint film.

By comparison of the paint film with the bubble level images of DIN EN ISO 4628-2, a matching is done according to the quantity and size of the craters and specks. Identifier letter and key figure meaning

m no damage

m l fewer bubbles or craters than figure 2, corresponds to (about 1/3) according to the bubble or crater degree images

m 2 to m 5

(analogous to the bubble level - pictures DIN EN ISO 4628-2)

Identifier letter and key figure meaning

g o no damage g l bubbles or craters visible with unaided eye

(Limit of the visible area)

corresponding to the bubble or crater level images g 2 to g 5

(analogous to the bubble level - pictures DIN EN ISO 4628-2)

Clearcoat test

For the clearcoat test, the coating materials were applied to a glass plate and dried for 20 minutes at 140 ° C in a laboratory oven.

Film evaluation: The film evaluation on the baked clearcoat film was analogous to the film evaluation of the infusion test. (OK = okay, tiO = partly okay, no = not ok)

Pendulum damping: The measurement of the pendulum damping was carried out according to DIN EN ISO 1522 on a glass plate and was determined by König.

Solvent resistance: To this was added a small amount of the appropriate solvents (xylene, 1-methoxypropylacetate-2, ethyl acetate or acetone (abbreviated as: XI / MPA / EA / acetone in Table 6) to a test tube and fitted with a cotton swab at the opening, so that a solvent-saturated atmosphere within the test tube was formed.The test tubes were then placed with the cotton swab on the paint surface and remained there for 1 minute. After wiping off the solvent, the film was tested for destruction / softening / adhesion loss. (0 = no change, 5 = film destroyed)

Yellowing: The yellowing was determined with a multi-angle spectrophotometer in reflection mode against a white tile. The measured values Δ b * were determined in accordance with DIN EN ISO 11664.

Based paint testing

The base paint tests were carried out in the complete setup. For this purpose, the sheet material was coated with a ΙΚ-OEM hydrofiller prior to application of the clearcoat. The filler was baked at 165 ° C for 20 minutes. Then, the basecoat was applied by means of a flow cup gun and flashed off at 80 ° C or pre-dried for 10 minutes. Subsequently, a 2K-PUR-OEM clearcoat was applied and baked at 140 ° C for 30 minutes.

Optics: The optics were assessed visually. Edge creep describes the contraction of the lacquer at the edges of the substrate, flooding describes the poor alignment / orientation of effect pigments. Flip-flop effect: The flip-flop effect was determined using a multi-angle spectrophotometer in accordance with DIN 6175-2.

Opacity: For the opacity, the basecoat was scrape on a black and white card and visually assessed.

Substances and Abbreviations Desmodur ^® W: 4,4'-diisocyanatodicyclohexylmethane, trans-trans content about 20 wt .-%, Bayer MaterialScience AG, Leverkusen, DE

Desmodur ^® I: l-isocyanato-3,3,5-trimethyl-5-isocyanatomethyl cyclohexane, Bayer MaterialScience AG, Leverkusen, DE

Desmophen ^® C 1200: Polycarbonatester (1,6-hexanediol, caprolactone), functionality = 2, average molecular weight = 2000 g / mol, Bayer MaterialScience AG, Leverkusen, DE

Polyesterpolyol I: polyesterpolyol of adipic acid and hexanediol, average molecular weight = 1700 g / mol

Methyl methacrylate (MMA): CAS 80-62-6, Sigma-Aldrich, DE

2-ethylhexyl acrylate (EHA): CAS 103-11-7, Sigma-Aldrich, DE

Ammonium persulfate (APS): CAS 7727-54-0, Sigma-Aldrich, DE

Tanemul 951: Emulsifier (Tanatex, DE) Butyl diglycol: 2- (2-butoxyethoxy) ethanol (BDGL): CAS 112-34-5, Colöser (Sigma-Aldrich, DE)

Byk 346: polyether-modified siloxane, additive for reducing surface tension to improve substrate wetting (Byk Chemie GmbH, DE)

Luwipal 073: melamine resin dissolved in water (BASF, DE)

DMEA: Ν, Ν-dimethylethanolamine, neutralizing agent (Sigma-Aldrich, DE)

Butyl glycol: 2-butoxyethanol (BG): CAS 111-76-2, Colöser (Sigma-Aldrich, DE)

Aquatix 8421: Rheology Modifying Wax Emulsion (Byk, DE)

Setaqua D E 270: water-dilutable polyester (Nuplex, DE)

Additol XL 250: wetting and dispersing additive (Allnex, BE)

Stapa Hydrolan 2156 No. 55900 / G Aluminum: aluminum pigment paste (Eckart, DE)

Other chemicals, unless otherwise stated, from Sigma-Aldrich Chemie GmbH, Taufkirchen, DE. Unless otherwise stated, the raw materials were used without further purification or pretreatment.

Example 1 Preparation of the Polyurethane Urea Dispersion as Precursor PUR 1 (According to the Invention)

A mixture of 308 g of Desmophen ^® C 1200, 25 g of dimethylolpropionic acid, 10 g of neopentyl glycol, 1 g of butyl glycol and 161 g of acetone were heated to 55 ° C and stirred. Then 41 g Desmodur ^® W and 93 g Desmodur ^® I were added and heated to 65 ° C. At this temperature was stirred until an NCO content of 1.8% was reached. It was then cooled to 60 ° C and 12 g of dimethyl ethanolamine was added. 648 g of this solution were with vigorous stirring in 812 g of water, which was initially charged at a temperature of 35 ° C, dispersed. After dispersion was stirred for 5 min. Subsequently, within 10 minutes, a solution of 3 g of diethylenetriamine and 2 g of ethylenediamine and 1 g of butylamine in 73 g of water was added. After complete addition, the mixture was stirred for 20 min at 40 ° C before the acetone was removed by distillation under vacuum at this temperature. For complete reaction of the isocyanate groups was stirred at 40 ° C until IR spectroscopy no NCO was detectable. After cooling to <30 ° C was filtered through a 240 μιη quick filter from. Erich rotary head.

Characteristics of the polyurethane dispersion:

Average particle size 54 nm pH (10% Fh, 20 ° C): 8.2 Solid content: 35% Viscosity (D 40 S ¹ ): 100 mPas

Example 2: Preparation of the polyurethane urea dispersion as a precursor PUR 2 (Comparative) A mixture of 202 g of Desmophen ^® C 1200, 172 g of polyester polyol I, 29 g of dimethylolpropionic acid, 8 g of neopentyl glycol, 1 g of butyl glycol and 188 g of acetone were heated to 55 ° C and stirred. Then 46 g Desmodur ^® W and 106 g Desmodur ^® I were added and heated to 65 ° C. At this temperature was stirred until an NCO content of 1.7% was reached. It was then cooled to 60 ° C and 14 g of dimethyl ethanolamine was added. 600 g of this solution were with vigorous stirring in 752 g of water, which was initially charged at a temperature of 35 ° C, dispersed. After dispersion was stirred for 5 min. Subsequently, a solution of 3 g of diethylenetriamine and 2 g of ethylenediamine and 1 g of butylamine in 67 g of water was added within 10 min. After complete addition, the mixture was stirred for 20 min at 40 ° C before the acetone was removed by distillation under vacuum at this temperature. For complete reaction of the isocyanate groups was stirred at 40 ° C until IR spectroscopy no NCO was detectable. After cooling to <30 ° C was filtered through a 240 μιη quick filter from. Erich rotary head.

Characteristics of the polyurethane dispersion:

Average particle size: 69nm pH (10% Fh, 20 ° C): 7.8

Fixed salary: 35%

Viscosity (D 40 S ¹ ): 120 mPas

Example 3 Preparation of the Polyurethane Urea Dispersion as Precursor PUR 3 (Comparison)

A mixture of 344 g of polyesterpolyol I, 29 g of dimethylolpropionic acid, 8 g of neopentyl glycol, 1 g of butylglycol and 178 g of acetone were heated to 55.degree. C. and stirred. Then 46 g Desmodur ^® W and 106 g Desmodur ^® I were added and heated to 65 ° C. At this temperature was stirred until an NCO content of 1.8% was reached. It was then cooled to 60 ° C and 14 g of dimethyl ethanolamine was added. 600 g of this solution were dispersed with vigorous stirring in 751 g of water, which was initially charged at a temperature of 35 ° C. After dispersion was stirred for 5 min. Subsequently, within 10 min, a solution of 3 g of diethylenetriamine and 2 g of ethylenediamine and 1 g of butylamine in 67 g of water added. After complete addition, the mixture was stirred for 20 min at 40 ° C before the acetone was removed by distillation under vacuum at this temperature. For complete reaction of the isocyanate groups was stirred at 40 ° C until IR spectroscopy no NCO was detectable. After cooling to <30 ° C was filtered through a 240 μιη quick filter from. Erich rotary head.

Characteristics of the polyurethane dispersion:

Average particle size 40nm pH (10% Fh, 20 ° C): 7.4 Solid content: 35% Viscosity (D 40 S ¹ ): 135 mPas

Example 4 Preparation of the Polyurethane Urea Dispersion as Precursor PUR 4 (Comparison)

A mixture of 376 g of Desmophen ^® C 1200, 29 g of neopentyl glycol, 1 g of butyl glycol and 190 g of acetone were heated to 55 ° C and stirred. Then, 50 g Desmodur ^® W and 116 g Desmodur ^® I were added and heated to 65 ° C. At this temperature was stirred until an NCO content of 2.7% was reached. The mixture was then cooled to 60 ° C and dissolved in 1122 g of acetone, and stirred for 5 min. Subsequently, a solution of 3 g of diethylenetriamine and 1 g of ethylenediamine and 2 g of butylamine and 58 g of sodium N- (2-aminoethyl) -2-aminoethanesulfonate in 93 g of water was added within 2 min. After complete addition, the mixture was stirred for 5 min, then followed by the addition of 998 g of water within 10 min. The mixture was then stirred for a further 20 min at 40 ° C before the acetone was removed by distillation under vacuum at this temperature. For complete reaction of the isocyanate groups was stirred at 40 ° C until IR spectroscopy no NCO was detectable. After cooling to <30 ° C was filtered through a 240 μιη quick filter from. Erich rotary head.

Characteristics of the polyurethane dispersion: Average particle size: 99 nm pH (10% Fh, 20 ° C): 7.6

Fixed salary: 35%

Viscosity (D 40 S ¹ ): 1560 mPas General Preparation of the Polyurethane-Polyacrylate Dispersion (PUR-PAC 1-4)

The following section describes a general synthesis procedure for the preparation of the PUR-PAC dispersions according to the invention, the specific compositions and characteristics of the individual experiments can be taken from Table 1. In a 3 L glass reactor with controlled heating and cooling and stirring a mixture of 2100 g of the respective polyurethane precursor (PUR 1 to PUR 4) and 234 g of water was placed under nitrogen and under moderate stirring (laboratory 150 U / min) in N2 overlaid Submitted to the reactor and heated to 75 ° C. A monomer mixture of 6 g of 2-ethylhexyl acrylate and 12 g of methyl methacrylate and an initiator solution of 0.1 g of APS and 10 g of water were added in parallel within 15 minutes. This was followed by stirring at 75 ° C for 30 minutes. Then, a monomer mixture of 54 g of 2-ethylhexyl acrylate and 108 g of methyl methacrylate and an initiator solution of 0.5 g of APS and 80 g of water were fed in parallel within 120 minutes.

Subsequently, the reaction mixture was stirred for an additional hour at 75.degree. Finally, it was cooled to 25-30 ° C. and the batch was filtered through a 125 μm filter.

Tab.l: formulations for the preparation of PUR-PAC dispersions PUR-PAC 1-4 (composition in wt .-% and characteristics of the respective dispersion).

PUR-PAC 1 PUR-PAC 2 PUR-PAC 3 PUR-PAC 4 according to the invention Comparison Comparison Comparison

PUR 1 80.2%

PUR 2 80.2%

PUR 3 80.2%

PUR 4 80.2%

Methyl methacrylate 13.1% 13.1% 13.1% 13.1%

Ethylhexyl acrylate 6.6% 6.6% 6.6% 6.6%

Ammonium persulfate 0.1% 0.1% 0.1% 0.1%

Characteristics: Particle size (nm) 66 87 59 107

Viscosity (D 40 S-l): 25 137 329 268

Solids content (%) 35 35 35 35 pH 7.6 7.4 7.2 7.0

Preparation of the polyurethane-polyacrylate dispersion (PUR-PAC 5, according to the invention)

In a 3 L glass reactor with controlled heating and cooling and stirring a mixture of 1500 g of polyurethane precursor PUR 1 and 256.5 g of water was placed under nitrogen atmosphere and heated to 75 ° C with moderate stirring (250 rev / min). A monomer mixture of 9 g of 2-ethylhexyl acrylate and 18.15 g of methyl methacrylate and an initiator solution of 0.29 g of APS and 70 g of water were added in parallel within 15 minutes. This was followed by stirring at 75 ° C for 30 minutes. Then, a monomer mixture of 81.9 g of 2-ethylhexyl acrylate and 163.7 g of methyl methacrylate, and an initiator solution of 0.3 g of APS and 129 g of water were fed in parallel within 120 minutes.

Preparation of a mixture of polyurethane and polyacrylate dispersion (PUR-PAC 6) (comparative) A mixture of 10.4 g of Tanemul 951 and 550 g of water was introduced into a 3 l glass reactor with controlled heating and cooling and stirring motor under nitrogen atmosphere and with moderate stirring (250 rev / min) heated to 80 ° C. A monomer mixture of 18 g of 2-ethylhexyl acrylate and 36.30 g of methyl methacrylate and an initiator solution of 0.50 g of APS and 70 g of water were added in parallel within 30 minutes. This was followed by stirring at 80 ° C. for 30 minutes. Then, a monomer mixture of 163.80 g of 2-ethylhexyl acrylate and 327.4 g of methyl methacrylate, and an initiator solution of 2.30 g of APS, 10.20 g of Tanemul 951 and 129 g of water were fed in parallel within 120 minutes.

Subsequently, the reaction mixture was stirred for a further hour at 80 ° C. Finally, it was cooled to 25-30 ° C. and the batch was filtered through a 125 μm filter. 420 g of the PAC dispersion thus obtained were then mixed in a 2L beaker with 780 g of polyurethane precursor PUR 1 with stirring and finally filtered again through a 125 μιη filter Table 2: Formulations for the preparation of the PUR-PAC dispersions PUR-PAC 5 and 6 (composition in% by weight and characteristics of the particular dispersion).

Preparation of the Polyurethane Polyacrylate Dispersion (PUR-PAC 7, Inventive) A mixture of 1305.5 g of the polyurethane precursor PUR 1, 300 g of styrene and 472.5 g of water was placed under a nitrogen atmosphere in a 3 L glass reactor with controlled heating and cooling and stirring moderate stirring (250 rev / min) heated to 75 ° C. This was followed by stirring at 75 ° C. for 60 minutes. Then, an initiator solution of 1.5 g of APS and 80 g of water was supplied within 120 minutes. Subsequently, the reaction mixture was stirred for an additional hour at 75.degree. Finally, the mixture was cooled to 25-30 ° C. and the mixture was filtered through a Seitz filter T 5500.

Preparation of a Polyurethane-Polyacrylate Dispersion (PUR-PAC 8) with a Lyophilic Initiator (Comparison)

In a 3 L glass reactor with controlled heating and cooling and stirring a mixture of 1305.5 g of the respective polyurethane precursor PUR 1, 270 g of styrene and 552.5 g of water was placed under nitrogen atmosphere and with moderate stirring (250 rev / min) to 80 ° C heated. This was followed by stirring at 80 ° C for 60 minutes. Then, an initiator solution of 1.5 g of azoisobutyronitrile and 30 g of styrene was supplied within 120 minutes.

Subsequently, the reaction mixture was stirred for a further hour at 80 ° C. Finally, the mixture was cooled to 25-30 ° C. and the mixture was filtered through a Seitz filter T 5500. Due to the increased viscosity, filtration was very difficult. The infusion test of the dispersion (50 g filtered sample + 300 g water) gave a very high speck content (film evaluation n.O.)

Thus, the dispersion PUR-PAC 8 can not be used as a varnish.

Table 3: Formulations for the preparation of PUR-PAC dispersions PUR-PAC 7 and 8 (composition in% by weight and characteristics of the particular dispersion).

Formulation of the dispersions

pour-on test

1 g of butyldiglycol and 2.2 g of dist. Water was mixed and then 0.03 g of Byk 346 was added. Subsequently, 10 g of the corresponding PUR-PAC 1 to PUR-PAC 4 Dispersion and the resulting mixture stored for about 30 minutes at room temperature before the infusion test was performed.

Tab. 4: Formulations for the preparation of the infusion film (composition in grams).

Clearcoat test

For the preparation of the test clearcoat, the components were weighed in succession and stirred together. With a DMEA solution, 5%, the pH was adjusted to 8.0-8.5.

Tab. 5: Formulations for the preparation of the clearcoat film (composition in grams).

1 cc 5 CC 6CC

2 CC 3 CC 4 CC

According to the invention according to

PUR-PAC 1 13,71

PUR-PAC 2 13,87

PUR-PAC 3 13,79

PUR-PAC 4 13,71 PUR-PAC 5 13,68

PUR-PAC 6 13,99

Luwipal 073, Form of Delivery 1.50 1.50 1.50 1.50 1.60 1.60

BYK 346, form of delivery 0.03 0.03 0.03 0.03 0.03 0.03 dist. Water 0,50 0,60 0,60 1,00

DMEA, 5% in dist. water

1.00 0.90 0.80 0.03 0.80 0.80 (to pH 8.0-8.5)

1K metallic basecoats

For the preparation of the basecoat, the PUR-PAC dispersion was initially charged and mixed with a mixture of dist. Water and butylglycol mixed. With a DMEA solution, 10%, the pH was adjusted to pH 8.0-8.5. The mixture was then stirred for 5 minutes at about 2000 rpm (5.2 m / s) under the dissolver. Then a mixture of Luwipal 073, butyl glycol and dist. Added water and stirred again for 5 minutes at about 2000 rev / min (5.2 m / s) under the dissolver. This was followed by the addition of the prepared metallic paste (Table 5), which was incorporated under the dissolver for 30 minutes at approximately 4000 rpm (10.5 m / s). Then Aquatix 8421 and dist. Water for 5 minutes at about 2000 rev / min (5.2 m / s) incorporated under the dissolver and then with dist. Water adjusted to spray viscosity (flow time 40 s in DIN cup, 4 mm nozzle).

Tab. 6: Formulations for the preparation of the basecoat film (composition in grams).

5 M 6 M 7 M 8 M

According to the invention

I. PU -PAC 1 153.74

PUR-PAC 2 155.51

PUR-PAC 3 154.62

PUR-PAC 3 153.74

II. Dest. Water 12,50 22,50 22,50 22,50

Butyl glycol 14.73 14.73 14.73 14.73

DMEA, 10% in dist. water

16,40 15,00 15,00 8,20 (to pH 8,0-8,5)

- 5 min. at about 2000 rpm. Stir (5.2 m / s) -

III. Luwipal 073, delivery form 16,82 16,82 16,82 16,82

Butyl glycol 14.73 14.73 14.73 14.73 dist. Water 12,50 22,50 22,50 50,00

- 5 min. at about 2000 rpm. Stir (5.2 m / s) -

IV. Metallic paste (see Table 5) 52.91 52.91 52.91 52.91

- 30 min. at about 4000 rpm. Stir (10.5 m / s) -

V. Aquatix 8421, Delivery form 18.83 18.83 18.83 18.83 dist. Water 32,50 32,50 32,50 70,00

- 5 min. at about 2000 rpm. Stir (5.2 m / s) -

VI. least. Water (on flow time 40 s

26.00 32.40 29.90 58.40 in DIN cup, 4 mm)

Total weight 371.66 398.43 395.04 480.86 Metallic paste

The components were weighed in succession and premixed under a propeller stirrer. The pH should be at pH 8.0-8.5 and, if necessary, adjusted with DMEA. Then, the paste was mixed at 10.5 m / sec under the propeller stirrer for 30 minutes, so that the temperature would not exceed 50 ° C as much as possible.

Tab. 7: Formulation for the preparation of the metallic paste (composition in grams).

Results

Evaluation of the Coating Film The advantages of the polyurethane-polyacrylate dispersions PUR-PAC 1 and PURPAC 5 according to the invention can be seen from the results of the technical paint test summarized in Table 8. In the case of the PUR-PAC 1 dispersion, in particular the improved hiding power compared to the dispersions from the comparative examples PUR-PAC 2-4 should be emphasized. The polyurethane-polyacrylate dispersions PUR-PAC 5 according to the invention, in comparison with the non-inventive polyurethane-polyacrylate dispersions PUR-PAC 6, have a significantly better film appearance and solvent resistance. In addition, the thermal yellowing of the PUR-PAC 5 is significantly lower than the Thermovergtlbung the non-inventive polyurethane-polyacrylate dispersions PUR-PAC. 6 Tab. 8: Properties of the paint film.

Testing of the loop stability

The loop stability of the aqueous polyurethane-polyacrylate dispersions was simulated by means of a Göttfert capillary rheometer. For this purpose, 500 g of the corresponding dispersion PU PAC 1 to PUR-PAC 4 were added to the container and pressed by means of a movable cylinder at a constant speed through an annular gap of 20μιη gap size. If the material is shear-stable, it can be pushed through the annular gap without pressure build-up. With non-shear stable material, the dispersion coagulates, clogging the nozzle and pressure build-up is detected. The shear forces simulated in this case can be calculated on the basis of the gap size and the speed and in the present case were 375,000 1 / s. The results of the measurement of the loop stability are shown in Figure 1. From the graphs it can be seen that the shear stability could be significantly improved by the polyurethane-polyacrylate dispersion PUR-PAC 1 according to the invention, since the pressure only increased slightly, while the pressure on testing the dispersions prepared as comparative examples (PUR-PAC 2 to 4 ) increased significantly and increased to higher pressures.

Claims

claims

An aqueous polyurethane-polyacrylate dispersion obtainable by free-radical polymerization of a component A) comprising an ethylenically unsaturated compound, at least in the presence of a component B) comprising water and a polyurethane resin obtainable by reacting the following constituent components

I) comprising at least one aliphatic, cycloaliphatic, araliphatic and / or aromatic compound having at least two or more isocyanate groups,

II) comprising at least one polycarbonate polyol having a middle one

Molecular weight of 500 to 3000 g / mol,

III) comprising at least one anionic hydrophilizing compound having at least one OH or NH functional group and containing a carboxyl and / or carboxylate group,

IV) comprising at least one polyol and / or polyamine having a middle one

Molecular weight between> 62 and <500 g / mol and optionally

V), comprising at least one or more monoalcohols and / or monoamines, wherein a hydrophilic initiator is used as the initiator of the radical polymerization.

Aqueous polyurethane-polyacrylate dispersion according to claim 1, wherein the component A) in 3 to 40 wt .-%, preferably in 5 to 30 wt .-% and particularly preferably in 7 to 25 wt .-%, the component B) in 97 to 60 wt .-%, preferably in 95 to 70 wt .-% and particularly preferably in 93 to 75 wt .-%, based on the total amount of the polyurethane-polyacrylate dispersion, are used and wherein the ratios are normalized, that they can not be greater than 100% even with the optional use of further components C) and particularly preferably complement each other to 100%.

Aqueous polyurethane-polyacrylate dispersion according to one of claims 1 or 2, wherein the hydrophilic initiator comprises one or more persulfate-containing compounds, preferably exclusively one or more persulfate-containing compounds, and more preferably exclusively ammonium peroxodisulfate, sodium peroxodisulfate and / or potassium peroxodisulfate is.

Aqueous polyurethane-polyacrylate dispersion according to any one of claims 1 to 3, wherein component A) comprises at least one aliphatic, cycloaliphatic or aromatic acrylate or methacrylate which comprises substituted or unsubstituted, preferably at least one aliphatic or cycloaliphatic, optionally alkyl-substituted acrylate or methacrylate and particularly preferably at least one mixture of one aliphatic, optionally alkyl substituted acrylate and an aliphatic, optionally alkyl substituted methacrylate.

Aqueous polyurethane-polyacrylate dispersion according to any one of claims 1 to 4, wherein the synthesis component I) at least one aliphatic, cycloaliphatic, aliphatic and / or aromatic diisocyanate, preferably a mixture of aliphatic and / or cycloaliphatic diisocyanates and more preferably a mixture of 1, 6- diisocyanatohexane, 1-isocyanate-3,3,5, -trimethyl-5-isocyanatomethylcyclohexane and / or 4,4'-diisocyanato-dicyclohexylmethane.

Aqueous polyurethane-polyacrylate dispersion according to any one of claims 1 to 5, wherein the polycarbonate polyol has an average molecular weight of 1000 to 3000 g / mol, preferably from 1250 to 2500 g / mol and particularly preferably from 1500 to 2100 g / mol. 7. Aqueous polyurethane-polyacrylate dispersion according to any one of claims 1 to 6, wherein the anionic hydrophilicizing compound is free of sulfonic acid groups and sulfonate groups, preferably dimethylolpropionic acid, dimethylolpropionate, N- (2-aminoethyl) -2-aminoethane-carboxylic acid and / or N - (2-aminoethyl) -2-aminoethanoate and particularly preferably consists of dimethylolpropionic acid, dimethylolpropionate, N- (2-aminoethyl) -2-aminoethanecarboxylic acid and / or N- (2-aminoethyl) -2-aminoethanoate.

8. Aqueous polyurethane-polyacrylate dispersion according to any one of claims 1 to 7, wherein the structural components I) to V) in proportions of

45 to 75 wt .-%, preferably 55 to 70 wt .-% of the synthesis component II),

0.1 to 15 wt .-%, preferably 3 to 10 wt .-% of the structural component III),

0.1 to 5 wt .-%, preferably 0.5 to 3 wt .-% of the structural component IV) and

0 to 5 wt .-%, preferably 0 to 3 wt .-% of the synthesis component V), based on the total solids content of the polyurethane resin are used and the proportions are chosen so that they can not be greater than 100%, and more preferably to

100% complete.

An aqueous polyurethane-polyacrylate dispersion according to any one of claims 1 to 8, wherein the structural component

I), consists of at least one aliphatic, cycloaliphatic, aliphatic and / or aromatic compound having at least two or more isocyanate groups, II), consists of at least one polycarbonate polyol having an average molecular weight of 500 to 3000 g / mol,

III), consists of at least one anionic hydrophilizing compound which has at least one OH or NH-functional group and contains a carboxyl and / or carboxylate group,

IV), from at least one polyol and / or polyamine with a middle

Molecular weight between> 62 and <500 g / mol.

An aqueous polyurethane-polyacrylate dispersion according to any one of claims 1 to 9, wherein component B) comprises a polyester polyol and / or a polyether polyol as further polyol component together to less than 10 wt .-%, based on the total weight of component B).

11. A process for preparing an aqueous polyurethane-polyacrylate dispersion according to any one of claims 1 to 10, wherein the free-radical polymerization of component A) in

Presence of at least the hydrophilic initiator and component B) is performed.

12. The method of claim 11, wherein the component B) is introduced and the radical polymerization by continuously metering the component A) in the presence of at least the hydrophilic initiator, which preferably also continuously in parallel with the metered addition of the component A) to the submitted component B. ) is added. 13. A coating composition containing at least one polyurethane-polyacrylate dispersion according to any one of claims 1 to 10 and at least one crosslinking agent and optionally further auxiliaries and additives.

14. Use of the coating composition according to claim 13 for the preparation of a coating on a substrate.

15. Coating obtainable by using the coating composition according to claim 14.

16. composite of a coating according to claim 15 and a substrate having a surface made of metal and / or plastic.