EP2209829A1

EP2209829A1 - Nanoparticle-modified polyisocyanates

Info

Publication number: EP2209829A1
Application number: EP08846543A
Authority: EP
Inventors: Arno Nennemann; Markus Mechtel; Thomas Klimmasch; Christoph Gürtler; Michael Mager; Meike Niesten; Robert Maleika
Original assignee: Bayer MaterialScience AG
Current assignee: Covestro Deutschland AG
Priority date: 2007-11-08
Filing date: 2008-10-24
Publication date: 2010-07-28
Also published as: CN101855265A; TW200936626A; JP2011503268A; WO2009059695A1; EP2058349A1; CA2704816A1; US20090124727A1

Abstract

The present invention relates to nanoparticle-modified polyisocyanates that are modified by a special siloxane component and therefore have improved properties for the use thereof and improved storage stability.

Description

Nanoparticle-modified polyisocyanates

The present invention relates to nanoparticle-modified polyisocyanates which are modified by a special siloxane unit and therefore have improved performance properties and storage stabilities.

US Pat. No. 6,593,417 discloses coating compositions which are based on a polyol component which, in addition to the nanoparticles, also contains polysiloxanes. The extent to which these polysiloxanes are suitable for the modification of polyisocyanates is not described.

EP-A 1 690 902 describes surface-modified nanoparticles whose surfaces are covalently bonded with polysiloxane components. Not described are polysiloxane-modified binders containing nanoparticles.

A number of patents describe surface-functionalized particles having groups which are potentially reactive with the coating resins and their use in coatings (EP-A 0 872 500, WO 2006/018144, DE-A 10 2005 034348, DE-A 199 33 098, DE 102 47 359). Inter alia, these are nanoparticles carrying blocked isocyanate groups and their dispersions, which are used in admixture with binders.

For example, EP-A 0 872 500 and WO 2006/018144 disclose colloidal metal oxides whose nanoparticle surfaces have been modified via covalent attachment of alkoxysilanes. The alkoxysilanes used for the modification are addition products of aminoalkoxysilanes and blocked, monomeric isocyanates. Such modified metal oxides are then mixed with the binders and hardeners or used as an isocyanate component for the production of paints. Essential to the invention here is the presence of water and alcohol in the manufacturing process for the hydrolysis of the alkoxy groups with the following condensation on the particle surfaces, whereby a covalent attachment is achieved. Also essential to the invention is a blockage of free NCO groups to prevent a reaction with water and alcoholic solvent. These are therefore modified nanoparticles and not nanoparticle-containing polyisocyanates. Accordingly, the nanoparticles are covalently bound in reaction in the paint matrix and thus dominate the paint matrix, which experience can lead to loss of flexibility. Another disadvantage is that due to this process, which makes the use of water and alcoholic solvent essential, no unblocked polyisocyanates can be used. Not described is the use of polysiloxane components.

WO 2007/025670 and WO 2007/025671 disclose hydroxy-functional polydimethylsiloxanes as part of a polyol component of polyurethane coatings. How far are such hydro- xyfiinktionellen polydimethylsiloxanes suitable for the modification of polyisocyanates is not addressed.

From the German patent application No. 10 2006 054289, nanoparticle-containing polyisocyanates are known, which are obtained by modifying polyisocyanates with aminoalkoxysilanes and adding nanoparticles.

It has now surprisingly been found that such nanoparticle-containing polyisocyanates can be advantageously modified by hydroxy-functional polydimethylsiloxanes, whereby a significant improvement in the performance properties of coating compositions prepared therefrom can be achieved.

The present invention therefore provides a process for the preparation of nanoparticle-modified polyisocyanates in which

A) polyisocyanates with

B) alkoxysilanes of the formula (I)

QZ-SiX ₃ Y _3-3 (I)

in which

Q is an isocyanate-reactive group,

X is a hydrolyzable group,

Y are identical or different alkyl groups

Z is a C] -Ci ₂ -alkylene group and

a is an integer from 1 to 3,

C) hydroxyl-containing polysiloxanes having number average molecular weights of 200 to 3000 g / mol and an average OH functionality of greater than or equal to 1.8 according to formula (II)

in which

X is an aliphatic, optionally branched C 1 - to Cio radical, preferably methyl,

Ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, tert-butyl-est, particularly preferably methyl or

Si - [- [0-CH ₂ -CHZ] _n -O-] unit with Z = H or methyl, preferably H and n = 1-12, preferably 1 to 5

or very particularly preferably a [-CH ₂ -O- (CH ₂ ) 1] --Si moiety with r = 1 to 4, preferably with r = 3,

a hydroxy-functional carboxylic ester of the formula

,OH

- ■ V Γ CH r>

where x = 3 to 5, preferably 5,

or preferably a -CH (OH) Y group in which

Y is a -CH ₂ -N (R ² R ³ ) group, wherein R ^{2 is} H, methyl, ethyl, n-propyl, iso-propyl, cyclohexyl, 2-hydroxyethyl, 2-hydroxypropyl -, 3-hydroxypropyl may be rest and

R ^{3 may be} a 2-hydroxyethyl, 2-hydroxypropyl, 3-hydroxypropyl radical,

R ^{1 may be} identical or different and is hydrogen or an optionally hetero atom-containing Cp to Cio hydrocarbon radical and n is 1 to 40

D) optionally blocking agents be implemented, and subsequently

E) inorganic particles having an average particle size (Z mean value) of less than 200 nm, determined by means of dynamic light scattering in dispersion, which are optionally surface-modified, are dispersed in.

It is essential that in the process according to the invention anhydrous is used, so no water is added separately, for example, as a component in the process or as a solvent or dispersant. The proportion of water in the process according to the invention is therefore preferably less than 0.5% by weight, more preferably less than 0.1% by weight, based on the total amount of components A) to E) used.

In principle, all NCO-functional compounds known per se to the person skilled in the art having more than one NCO group per molecule can be used in A). These preferably have NCO functionalities of 2.3 to 4.5, contents of NCO groups of 11.0 to 24.0 wt .-% and contents of monomeric diisocyanates of preferably less than 1 wt .-%, more preferably less 0.5 wt .-% on.

Such polyisocyanates are obtainable by modifying simple aliphatic, cycloaliphatic, aromatic and / or aromatic diisocyanates and may have uretdione, isocyanurate, allophanate, biuret, iminooxadiazinedione and / or oxadiazinetrione structures. In addition, such polyisocyanates can be used as NCO-containing prepolymers. Such polyisocyanates are described, for example, in Laas et al. (1994), J. prakt. Chem. 336, 185-200 or in Bock (1999), Polyurethanes for coatings and coatings, Vincentz Verlag, Hannover, pp. 21-27.

Suitable diisocyanates for the preparation of such polyisocyanates are any diisocyanates of the molecular weight range 140 to 400 g / mol which are obtainable by phosgenation or by phosgene-free processes, for example by thermal urethane cleavage, with aliphatically, cycloaliphatically, araliphatically and / or aromatically bound isocyanate groups, such as 1, 4- diisocyanatobutane, 1,6-diisocyanatohexane (HDI), 2-methyl-1,5-diisocyanatopentane, 1,5-diisocyanato-2,2-dimethylpentane, 2,2,4- and 2,4,4-trimethyl -l, 6-diisocyanatohexane, 1,10-diisocyanatodecane, 1,3- and 1, 4-diisocyanatocyclohexane, 1,3- and 1, 4-bis (isocyanatomethyl) cyclohexane, 1-isocyanato-3,3,5 -trirnethyl-5-isocyanatomethylcyclohexane (isophorone diisocyanate, EPDI), 4,4'-diisocyanatodicyclohexylmethane, 1-isocyanato-1-methyl-4 (3) isocyanato-methylcyclohexane, bis (isocyanatomethyl) -norboman, 1,3- and 1, 4-bis (1-isocyanato-1-methylethyl) benzene (TMXDI), 2,4- and 2,6-diisocyanatotoluene (TDI), 2,4'- and 4,4'-diisocyanato diphenylmethane (MDI), 1,5-diisocyanatonaphthalene or any desired mixtures of such diisocyanates. Polyisocyanates of the abovementioned type based on IPDI, MDI, TDI, HDI or mixtures thereof are preferably used in A), particularly preferably HDI and IPDI.

In formula (I), the group X is preferably an alkoxy or hydroxy group, more preferably methoxy, ethoxy, propoxy or butoxy.

Y in formula (I) preferably represents a linear or branched C 1 -C ₄ -alkyl group, preferably methyl or ethyl.

Z in formula (I) is preferably a linear or branched C 1 -C ₄ -alkylene group.

Preferably, a in formula (I) is 1 or 2.

In formula (I), the group Q is preferably a group which reacts with isocyanates with urethane, urea or thiourea formation. These are preferably OH, SH or primary or secondary amino groups.

Preferred amino groups correspond to the formula -NHR ¹ , where R ^{1 is} hydrogen, a Ci-Ci ₂ - alkyl group or a C ₆ -C ₂ o-aryl group or an aspartic acid ester radical of the formula R ² OOC-CH ₂ -CH (COOR ³ ) -, wherein R ² , R ^{3 are} preferably identical or different alkyl radicals, which may optionally also be branched, having 1 to 22 carbon atoms, preferably 1 to 4 carbon atoms. Particularly preferably, R ² , R ^{3 are} each methyl or ethyl radicals.

Such alkoxysilane-functional aspartic acid esters are obtainable in a manner known per se by addition of amino-functional alkoxysilanes to maleic or fumaric acid esters, as described in US Pat. No. 5,364,955.

Arninoflinktionelle alkoxysilanes, as they can be used as compounds of formula (I) or for the preparation of the alkoxysilyl-functional aspartic acid esters, for example, 2-aminoethyldimethylmethoxysilane, 3 -aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3 -aminopropylmethyldimethoxysilane, Aminopropylmethyldiethoxysilan.

Furthermore, as aminoalkoxysilanes with secondary amino groups of the formula (I) in B), N-methyl-3-aminopropyltrimethoxysilane, N-methyl-3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, bis (gamma-trimethoxysilylpropyl) amine, N Butyl-3-aminopropyltrimethoxysilane, N-butyl-3-aminopropyltriethoxysilane, N-ethyl-3-aminoisobutyltrimethoxysilane, N-ethyl-3-aminoisobutyltriethoxysilane or N-ethyl-3-aminoisobutylmethyldimethoxysilane, N-ethyl-3-aminoisobutylmethyldiethoxysilane. Suitable maleic or fumaric acid esters for preparing the aspartic acid esters are maleic acid dimethyl ester, diethyl maleate, di-n-butyl maleate and the corresponding fumaric esters. Dimethyl maleate and diethyl maleate are particularly preferred.

Preferred aminosilane for preparing the aspartic acid esters is 3-aminopropyltrimethoxysilane or 3-aminopropyltriethoxysilane.

The reaction of maleic or fumaric acid esters with aminoalkyl alkoxysilanes is carried out within a temperature range of 0 to 100 ⁰ C, the proportions are generally chosen so that the starting compounds in a molar ratio of 1: 1 are used. The reaction can be carried out in bulk or in the presence of solvents such as dioxane. However, the incorporation of solvents is less preferred. Of course, it is also possible to react mixtures of different 3-aminoalkylalkoxysilanes with mixtures of fumaric and / or maleic acid esters.

Preferred alkoxysilanes for modifying the polyisocyanates are secondary aminosilanes of the type described above, more preferably aspartic acid esters of the type described above, and di- or monoalkoxysilanes.

The abovementioned alkoxysilanes can be used individually but also in mixtures for modification.

In the modification, the ratio of free NCO groups of the isocyanate to be modified to the NCO-reactive groups Q of the alkoxysilane of the formula (I) is preferably 1: 0.01 to 1: 0.75, particularly preferably 1: 0.02 to 1: 0.4, most preferably 1: 0.05 to 1: 0.3.

In principle, it is of course also possible to modify higher proportions of NCO groups with the abovementioned alkoxysilanes, but care must be taken that the number of free NCO groups available for crosslinking is still sufficient for satisfactory crosslinking.

The reaction of aminosilane and polyisocyanate is carried out at 0 to 100 ⁰ C, preferably at 0 to 50 ⁰ C, more preferably at 15 to 40 ⁰ C. Optionally, an exothermic reaction can be controlled by cooling.

The hydroxyl-containing siloxanes C) of the general formula (H) are obtainable by reacting corresponding epoxyfunctional polyorganosiloxanes with hydroxyalkyl-functional amines, preferably in a stoichiometric ratio of epoxy group to amino function. The epoxy-functional siloxanes used for this purpose preferably have 1 to 4, particularly preferably 2, epoxy groups per molecule. Furthermore, they have number average molecular weights of 150 to 2000 g / mol, preferably from 250 to 1500 g / mol, very particularly preferably from 250 to 1250 g / mol.

Preferred epoxy-functional siloxanes are α, ω-epoxysiloxanes corresponding to the formula (DI),

in which

X is an aliphatic, optionally branched Cj- to Ci ₀ -ReSt, preferably methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, tert-butyl, particularly preferably methyl or a [-CH ₂ -O- (CH ₂ ), -] - Si unit with r = 1 to 4, preferably with r = 3,

R ^{1 may be} identical or different and is hydrogen or an optionally heteroatom-containing Q- to Ci ₀ hydrocarbon radical and

n is 1 to 40.

R ¹ in the formulas (II) and (HT) is preferably phenyl, alkyl, aralkyl, fluoroalkyl, alkylethylene copropylene oxide groups or hydrogen, with phenyl or methyl groups being particularly preferred. Most preferably, R ^{1 is} a methyl group.

Suitable compounds corresponding to formula (HI) are, for example, those of the formulas IIa) and MB):

in which

n is an integer from 4 to 12, preferably from 6 to 9.

Examples of commercially available products of this series are for example COATOSIL ^® 2810 (Momentive Performance Materials, Leverkusen, Germany) or Tegomer® ^® E-Si2330 (Tego Chemie Service GmbH, Essen, Germany).

Suitable hydroxyalkyl-functional amines correspond to the general formula (IV)

in which

R ^{2 may be} H, methyl, ethyl, n-propyl, iso-propyl, cyclohexyl, 2-hydroxyethyl, 2-hydroxypropyl, 3-hydroxypropyl, and

R ^{3 may be} 2-hydroxyethyl, 2-hydroxypropyl, 3-hydroxypropyl,

Preferred hydroxyalkylamines are ethanolamine, propanolamine, diethanolamine, diisopropanolamine, methylethanolamine, ethylethanolamine, propylethanolamine and cyclohexyl-ethanolamine. Diethanolamine, diisopropanolamine or cyclohexylethanolamine are particularly preferred. Very particular preference is given to diethanolamine.

For the preparation of component C), the epoxy-functional siloxane of the general formula (III) is optionally introduced in a solvent and then reacted with the required amount of the hydroxyalkylamine (IV) or a mixture of several hydroxyalkylamines (IV). The Reaction temperature is typically 20 to 150 ° C and is carried out until no more free epoxy groups are detectable.

Particular preference is given to using hydroxyalkyl-functional siloxanes C) of the formula (II) obtained by reacting epoxy-functional polyorganosiloxanes with hydroxyalklyamines as listed above.

Particularly preferred polyorganosiloxanes C) are, for example, those of the formulas Ia) to Ih):

where n = 4 to 12, preferably 6 to 9.

Also suitable as component C) are, for example, hydroxyalkyl-functional siloxanes (α, ω-carbinols) corresponding to formula (V),

in which

m 5 to 15,

H or methyl, preferably H and

n, o is 1 to 12, preferably 1 to 5.

Hydroxyalkyl-functional siloxanes (α, ω-carbinols) of the formula (V) preferably have number-average molecular weights of from 250 to 2250 g / mol, particularly preferably from 250 to 1500 g / mol, very particularly preferably from 250 to 1250 g / mol. Examples of commercially available hydroxyalkyl-functional siloxanes of the type mentioned are Baysilone® OF-OH 502 3 and 6% strength (GE Bayer Silicones, Leverkusen, Germany).

Another way to prepare suitable hydroxy-functional polyorganosiloxanes corresponding to component C) is the reaction of the abovementioned hydroxyalkyl-functional siloxanes. ne of the α, co-carbinol type of the formula (V) with cyclic lactones. Suitable cyclic lactones are, for example, ε-caprolactone, γ-butyrolactone or valerolactone.

This is done in a ratio of OH groups to Lactonfiinktionen of 1: 2 to 2: 1, preferably in a stoichiometric ratio of OH groups to Lactonfunktionen. The thus obtained hydroxyalkyl-functional siloxanes C) are preferred. Exemplary of such a compound are polyorganosiloxanes C) of the general formula (VI)

in which

m = 5 to 15 and

y = 2 to 5, preferably 5 can be.

R in formula (II) is preferably a hydroxy-functional carboxylic acid ester of the formula

where x = 3 to 5, preferably 5,

or a hydroxyalkyl-functional amino group of the formula

in which

R ^{2 is} an aliphatic linear, branched or cyclic hydroxyalkyl radical and

R ^{3 is} hydrogen or according to the definition of the radical R ² .

R in formula (H) is particularly preferably a hydroxyalkyl-functional amino group of the abovementioned type. R ¹ in formulas (II) and (EI) is preferably phenyl, alkyl, aralkyl, fluoroalkyl, alkylethylene copropylene oxide groups or hydrogen, with phenyl and methyl being particularly preferred. The two R 'substituents on a Si atom may also differ. Most preferably, R ^{1 is} a methyl group, so that it is pure Dimethylsilyleinheiten.

Preferably, the hydroxyl-containing siloxanes of component C) obtainable as described above have number-average molecular weights of from 250 to 2250 g / mol, more preferably from 250 to 1500 g / mol.

In the modification, the ratio of free NCO groups of the polyisocyanate to be modified used in A) to the NCO-reactive OH groups of the hydroxyl-containing polydimethylsiloxane of the formula (II) is preferably 1: 0.001 to 1: 0.4, particularly preferably 1: 0.01 to 1: 0.2.

Following the silane and polydimethylsiloxane modification, the free NCO groups of the polyisocyanates modified in this way can be further modified. This may, for example, be a partial or complete blockage of the free NCO groups with blocking agents known to those skilled in the art (for blocking isocyanate groups see DE-A 10226927, EP-A 0 576 952, EP-A 0 566 953, EP-A 0 159 117, US Pat. No. 4,482,721, WO 97/12924 or EP-A 0 744 423). Examples include butanone oxime, ε-caprolactam, methyl ethyl ketoxime, malonic acid esters, secondary amines and triazole and pyrazole derivatives.

Blocking of the NCO groups prior to incorporation of the nanoparticles has the advantage that the nanoparticle-modified polyisocyanates based thereon tend to have better stability with respect to the content of later-available NCO groups than analogous products which still have free NCO groups have.

The modification of the polyisocyanates is preferably carried out in the order polydimethylsiloxane, silane and blocking agent.

The reaction of hydroxyl-functional polydimethylsiloxane and polyisocyanate is carried out at 0 - 100 ⁰ C, preferably at 10 - 90 ⁰ C, particularly preferably at 15-80 ⁰ C. If necessary, can be employed which catalyze the reaction R-OH with NCO conventional catalysts.

In principle, in any case, in the process according to the invention, the solvents which are known per se to the person skilled in the art and which are inert toward NCO groups can be added at any time. These are, for example, solvents such as butyl acetate, 1-methoxy-2-propyl acetate, ethyl acetate, toluene, xylene, sol ventnaphta and mixtures thereof. During or after the modification of the polyisocyanate, the optionally surface-modified nanoparticles E) are introduced. This can be done by simply stirring in the particles. However, it is also conceivable to use increased dispersing energy, as can be done, for example, by ultrasound, jet dispersion or high-speed stirrer according to the rotor-stator principle. Preferred is simple mechanical stirring.

The particles can in principle be used both in powder form and in the form of suspensions or dispersions in suitable, preferably isocyanate-inert solvents. The use of the particles in the form of dispersions in organic solvents is preferred.

Suitable solvents for the organosols are methanol, ethanol, isopropanol, acetone, 2-butanone, methyl isobutyl ketone, and the solvents commonly used in polyurethane chemistry, such as butyl acetate, ethyl acetate, 1-methoxy-2-propyl acetate, toluene, 2-butanone, xylene, 1,4-dioxane, diacetone alcohol, N-methylpyrrolidone, dimethylacetamide, dimethylformamide, dimethyl sulfoxide, methyl ethyl ketone or any mixtures of such solvents.

Preferred solvents here are the solvents commonly used in polyurethane chemistry, such as butyl acetate, ethyl acetate, 1-methoxy-2-propyl acetate, toluene, 2-butanone, xylene, 1,4-dioxane, discrete alcohol, N-methylpyrrolidone, dimethylacetamide, dimethylformamide, Dimethyl sulfoxide, methyl ethyl ketone or any mixtures of such solvents.

Particularly preferred solvents are alcohol and ketone-free solvents such as butyl acetate, 1-methoxy-2-propyl acetate, ethyl acetate, toluene, xylene, Solventnaphta and mixtures thereof.

With regard to the content of later available for crosslinking NCO groups, it has proven to be advantageous to dispense with ketones or alcohols as a solvent for both the particle dispersions and as a process solvent during the Polyisocyanatmodifizierung, since in this case a relatively higher degradation of NCO Groups can be observed during storage of the nanoparticle-modified polyisocyanates prepared therefrom. If the polyisocyanates are blocked in an additional step, it is also possible to use ketones or alcohols as solvents.

In a preferred embodiment of the invention are used as particles in E) inorganic oxides, mixed oxides, hydroxides, sulfates, carbonates, carbides, borides and nitrides of elements of II to IV main group and / or elements of I to VTJI subgroup of the periodic table including the lanthanides , Particularly preferred particles of component E) are Silica, alumina, ceria, zirconia, zinc oxide, niobium oxide and titanium oxide. Very particular preference is given to silica nanoparticles.

The particles used in E) preferably have mean particle sizes determined by dynamic light scattering in dispersion as Z mean value of 5 to 100 nm, more preferably 5 to 50 nm.

Preferably, at least 75%, more preferably at least 90%, most preferably at least 95% of all particles used in E) have the above-defined sizes.

The particles are preferably used surface-modified. If the particles used in E) are to be surface-modified, they are reacted, for example by silanization, prior to incorporation into the modified polyisocyanate. This method is known from the literature and described for example in DE-A 19846660 or WO 03/44099.

Furthermore, the surfaces can be adsorptively / associatively modified by surfactants having head groups of corresponding interactions with the particle surfaces or block copolymers, as described, for example, in WO 2006/008120 and Foerster, S. & Antonietti, M., Advanced Materials, 10, no. 3 , (1998) 195.

Preferred surface modification is the silanization with alkoxysilanes and / or chlorosilanes. Very particular preference is given to silanes which, in addition to the alkoxy groups, bear inert alkyl or aralkyl radicals but no further functional groups.

Examples of commercial particle dispersions as they are suitable for e) Organosilicasol ™ (Nissan Chemical America Corporation, USA), Nanobyk ^® (3650 BYK Chemie, Wesel, Germany), Hanse XP21 / 1264 or Hanse XP21 / 1184 (Hanse Chemie, Hamburg, Germany), HIGH LINK ^® NanO G (Clariant GmbH, Sulzbach, Germany). Suitable organosols have a solids content of 10 to 60 wt .-%, preferably 15 to 50 wt .-% to.

The content of the particles used in E) (calculated as solids) based on the total system of modified polyisocyanate and particles is typically from 1 to 70% by weight, preferably from 5 to 60, particularly preferably from 25 to 55% by weight.

The solids content of the present invention, nanoparticle-polyisocyanates is 20 to 100 wt .-% preferably 40 ₅ to 90 wt .-%, particularly preferably 40 to 70 wt .-%.

The invention further provides the nanoparticle-modified polyisocyanates obtainable according to the invention and also polyurethane systems which contain them. Such polyurethane systems may be formulated as 1- or 2-component PUR systems, depending on whether the NCO groups of the polyisocyanates of the present invention are blocked.

In addition to the nanoparticle-modified polyisocyanates according to the invention, the polyurethane systems of the present invention comprise polyhydroxy and / or polyamine compounds for crosslinking. In addition, other polyisocyanates which are different from the polyisocyanates according to the invention and also auxiliaries and additives may be present.

Suitable polyhydroxyl compounds are, for example, tri- and / or tetrafunctional alcohols and / or the polyether polyols, polyester polyols and / or polyacrylate polyols customary in coating technology.

In addition, polyurethanes or polyureas which can be crosslinked with polyisocyanates because of the active hydrogen atoms present in the urethane or urea groups can also be used for crosslinking.

Also possible is the use of polyamines whose amino groups may be blocked, such as polyketimines, polyaldimines or oxazolanes.

Polyisocyanate polyols and polyester polyols are preferably used for crosslinking the polyisocyanates according to the invention.

Suitable auxiliaries and additives may be solvents such as butyl acetate, ethyl acetate, 1-methoxy-2-propyl acetate, toluene, 2-butanone, xylene, 1,4-dioxane, diacetone alcohol, N-methylpyrrolidone, dimethylacetamide, dimethylformamide, dimethyl sulfoxide or any desired mixtures such solvents are used. Preferred solvents are butyl acetate, 2-ethyl acetate and diacetone alcohol.

Furthermore, as auxiliaries and additives, inorganic or organic pigments, light stabilizers, coating additives, such as dispersants, flow, thickening, defoaming and other auxiliaries, adhesives, fungicides, bactericides, stabilizers or inhibitors and catalysts may be included.

The application of the polyurethane systems of the invention to substrates is carried out according to the usual in coating technology application method, such. As spraying, flooding, diving, spin or knife. Examples:

Unless otherwise noted, percentages are by weight.

Desmophen ^® A 870 Polvacrvlatpolvol. 70% in butyl acetate, OH number 97, OH content 2.95%, viscosity at 23 ⁰ C 3500 mPas, product of Bayer MaterialScience AG, Leverkusen, DE

Desmodur ^® N 3300: hexamethylene diisocyanate trimer; NCO content 21.8 +/- 0.3 wt .-%, viscosity at 23 ° C about 3000 mPas, Bayer MaterialScience AG, Leverkusen, DE

Desmodur ^® N 3390 BA: hexamethylene diisocyanate trimer in butyl acetate; NCO content 19.6 +/- 0.3% by weight, viscosity at 23 ° C. about 500 mPas, Bayer MaterialScience AG, Leverkusen, DE

Desmodur ^® VP LS 2253: 3,5-dimethylpyrazole-blocked polyisocyanate (trimer) based on HDI; 75% in SN 100 / MPA (17: 8), viscosity at 23 ° C about 3600 mPas, blocked NCO content 10.5%, equivalent weight 400, Bayer MaterialScience AG, Leverkusen, DE

Organosilicasol ™ MEK-ST: colloidal silica dispersed in methyl ethyl ketone, particle size 10-15 nm (manufacturer), 30 wt% SiO ₂ , <0.5 wt% H ₂ O, <5 mPa s viscosity, Nissan Chemical America Corporation, USA ,

Coatosil 2810: Epoxy-modified silicone fluid epoxy content 11.4%. Momentive Performance Materials, Leverkusen, DE.

Bavsilone® paint additive OL 17: flow control agent, Borchers GmbH, Langenfeld, DE)

BYK ^® 070: defoamers, BYK-Chemie GmbH, Wesel, DE

Tinuvin ^® 123: HALS amine, Ciba Specialty Chemicals, Basel, CH

Tinuvin ^® 384-2: UV absorber, Ciba Specialty Chemicals, Basel, CH

Solvent naphtha ^® 100: aromatics-solvent mixture, Bayer MaterialScience AG, Leverkusen, DE

The determination of the hydroxyl number (OH number) was carried out according to DIN 53240-2.

The viscosity was determined by means of a rotational viscometer "RotoVisco 1" from Haake, Germany in accordance with DIN EN ISO 3219.

The determination of the acid number was carried out in accordance with DIN EN ISO 2114. The color number determination (APHA) was carried out in accordance with DIN EN 1557.

The determination of the NCO content was carried out in accordance with DIN EN ISO 11909.

Pendulum damping (König) according to DIN EN ISO 1522 "pendulum damping test"

Chemical resistance * according to DIN EN ISO 2812-5 "Paints and varnishes - Determination of resistance to liquids - Part 5: Method with gradient oven"

Scratch resistance Laboratory scrubber (wet scratching) according to DIN EN ISO 20566 "Coating materials - Scratch resistance of a coating system with a laboratory scrubber"

Determination of the particle size

Particle sizes were determined by dynamic light scattering with an HPPS particle size analyzer (Malvern, Worcestershire, UK). The evaluation took place via the Dispersion Technology Software 4.10. In order to avoid multiple scattering, a highly diluted dispersion of the nanoparticles was prepared. One drop of a diluted nanoparticle dispersion (about 0.1-10%) was placed in a cuvette containing about 2 ml of the same solvent as the dispersion, shaken and measured in HPPS analyzer at 20 to 25 ⁰ C. As is generally known to those skilled in the art, the relevant parameters of the dispersing medium - temperature, viscosity and refractive index - were previously entered into the software. In the case of organic solvents, a glass cuvette was used. As a result, an intensity-volume particle diameter curve and the Z-average particle diameter were obtained. Care was taken that the polydispersity index was <0.5.

Determination of solvent resistance

With this test, the resistance of a cured paint film was determined against various solvents. For this purpose, the solvents are allowed to act on the paint surface for a certain time. Subsequently, it is judged visually and by manual palpation whether and which changes have occurred on the test area. The paint film is usually on a glass plate, other substrates are also possible. The test tube rack with the solvents xylene, l-Methoxypropylacetat-2, ethyl acetate and acetone (see below) is placed on the paint surface so that the openings of the test tubes with the cotton wool pads rest on the film. Important is the resulting wetting of the paint surface by the solvent. After the specified exposure time of the solvents of 1 minute and 5 minutes, the test tube rack is removed from the paint surface. Subsequently, the solvent residues are removed immediately by means of an absorbent paper or textile fabric. One looks at the now immediately Test surface after careful scratching with the fingernail visually for changes. The following levels are distinguished:

0 = unchanged

1 = track changes only visible change

2 = slightly changed noticeable softening with fingernail

3 = noticeably changed with the fingernail strong softening noticeable

4 = heavily changed with the fingernail to the ground

5 = destroyed destroys paint surface without external influence

The evaluation levels found for the above solvents are documented in the following order:

Example 0000 (no change)

Example 0001 (visible change only with acetone)

The order of numbers describes the successors of the tested solvents (xylene, methoxypropyl acetate, ethyl acetate, acetone)

Determination of scratch resistance by hammer test (dry scratching)

The scratching is performed with a hammer (weight: 800 g without handle), on the flat side of which steel wool or polishing paper are fastened. For this purpose, the hammer is carefully placed at right angles to the coated surface and without tilting and out without additional physical force in a track on the coating. There will be 10 double strokes. After loading with the scratching medium, the test surface is cleaned with a soft cloth and then the gloss measured according to DIN EN ISO 2813 transversely to the direction of scribing. Only homogeneous areas may be measured.

example 1

N- (3-trimethoxysilylpropyl) aspartic acid diethyl ester was prepared according to the teaching of US Pat. No. 5,364,955, Example 5, by reacting equimolar amounts of 3-aminopropyltrimethoxysilane with diethyl maleate. Example 2a: hydroxy-functional polydimethylsiloxane

Corresponding to WO 2007025670 770 g of the epoxy-functional polydimethylsiloxane Coat- sosil ^® were 2,810

initially charged, preheated to 80 ⁰ C and with 231 g of diethanolamine (ratio of epoxide / amine 1: 1). This mixture was then stirred for 2 hours at 100 ⁰ C. The product had an epoxide content <0.01%, an OH number of about 365 mg KOH / g (11.1%) and a viscosity at 23 ° C of about 2900 mPas.

Example 2b - 2c

Analogously to Example 2a, the reaction of bisepoxide with various amines was carried out. The epoxide contents were <0.01% after the reaction subsided. In part, the synthesis was carried out in the presence of butyl acetate.

Example 2d

438 g (2 eq) of the PDMS bishydroxide Tegomer H-Si2111 (OH content 3.9%, molecular weight 876 g / mol, Degussa AG, Essen, DE) were mixed with 57 g of caprolactone (1 eq) and 0.05%. w / w DBTL mixed and stirred at 150 ⁰ C for 6 h. A transparent product with an OH number of 113 mg KOH / g was obtained. Example 3

In a 2 L flask, 500 g of Organosilicasol ™ MEK-ST and 500 g of butyl acetate were weighed. The dispersion was concentrated in a rotary evaporator at 60 ⁰ C and 120 mbar and the residue was replenished with 500 g of butyl acetate. This process was repeated until the proportion of methyl ethyl ketone in the dispersion had dropped below 0.1% by weight (determined by means of GC-FID).

Both the Organosilicasol ™ MEK-ST used in Example 3 and the butyl acetate and the resulting dispersion in butyl acetate were each dried over molecular sieve 4A.

The water content of the resulting silica organosol in butyl acetate was 440 ppm. The solids content was adjusted to 30% by weight. The Z mean value determined by dynamic light scattering was 23 nm.

Example 5 Comparative Polyisocyanate According to DE 10 2006 054289

m a standard stirred apparatus 192.7 g (1 eq) of Desmodur ^® N3300 (hexamethylene diisocyanate trimer; NCO content 21.8 +/- 0.3 wt .-%, viscosity at 23 ° C 3000 mPas, Bayer MaterialScience AG, Leverkusen, DE) in 85 g of butyl acetate at 60 ⁰ C submitted. Then carefully 70.3 g (0.2 eq) of the alkoxysilane was added dropwise in Example 1, with the temperature being kept at a maximum of 60 ⁰ C. After completion of the reaction (checking the NCO content IR spectroscopy to constant) was cooled to RT and cautiously 76.9 g of 1,3-dimethylpyrazole (DMP) was added and the temperature maintained at 50 ⁰ C until the NCO peak in IR spectrometer had disappeared.

This gave a colorless, liquid, blocked polyisocyanate having the following characteristics: solids content 80 wt .-%, viscosity 3440 mPas at 23 ° C and 7.91% blocked NCO content based on DMP.

Example 6a: essential silane- and siloxane-modified PIC according to the invention

In a standard stirred apparatus 275.85 g h of nitrogen (1 eq) of Desmodur ^® introduced into 250 g of butyl acetate at 80 ⁰ C N3300 and 2 l / transferred. Subsequently, 4.41 g (0.02 eq) was added the siloxane block copolyol from Example 2a at 80 ⁰ C and the temperature was held for 4 h. The theoretically expected NCO content was checked titrimetrically and then cooled to room temperature. 112.88 g within 3 h (0.2 eq) of the alkoxysilane from Example 1 and 250 g of butyl acetate, wherein the temperature was maintained by ice-cooling below 40 ^0C. After checking the theoretical NCO content was cooled to RT and in about 15 min Added 106.87 g (0.78 equivalent) of the blocking agent dimethylpyrazole while controlling the temperature to a maximum of 40 ° C. The temperature was kept at 40 ^° C. until the NCO peak in the d-spectrometer had disappeared.

This gave a clear, liquid, blocked polyisocyanate having the following characteristics: solids content 48.7% by weight and 4.67% blocked NCO content based on DMP.

Example 6b to 6h

Analogously to Example 6a, further modified PICs essential to the invention were prepared. As a polyisocyanate Desmodur N3300 was used. Optionally, the polysiloxane component was mixed with 50 g of butyl acetate. The VaI ratios PIC / polysiloxane / silane / blocking agent were chosen to be 1 / 0.02 / 0.2 / 0.78. Clear, storage-stable products were obtained.

NCO content: based on blocking agent Example 7: siloxane-modified comparative polyisocvanate without aminosiloxane modification

In a standard stirred apparatus 332.73 g h of nitrogen (1 eq) of Desmodur ^® introduced into 250 g of butyl acetate at 80 ⁰ C N3300 and 2 l / transferred. Subsequently, 5.31 g (0.02 eq) of the Siloxanblockcopolyols from Example 2 was added at 80 ⁰ C and the temperature maintained for 4 h. The theoretically expected NCO content was checked titrimetrically and then cooled to room temperature and 250 g of butyl acetate was added. After checking the theoretical NCO content was cooled to RT and added in about 15 min 161.95 g (0.98 eq) of the blocking agent dimethylpyrazole while controlling the temperature to a maximum of 40 ⁰ C. The temperature was maintained at 40 ⁰ C. until the NCO peak in the IR spectrometer had disappeared.

A cloudy, flaky, blocked polyisocyanate having the following characteristics was obtained: solids content 49.7% by weight and 7.08% blocked NCO content based on DMP.

Example 8a: Comparative Polvocyanate, containing nanoparticles

344.2 g of the product from Example 5 were initially charged in a standard stirring apparatus and admixed with 955.8 g of Organosilicasol ™ MEK-ST within 30 minutes. The resulting modified polyisocyanate had an NCO content of 2.1% by weight at a solids content of 42.7% by weight. The proportion of SiO ₂ nanoparticles in the dispersion was 22% by weight and in the solid 50.8% by weight. The product was slightly cloudy and a little yellowish.

Subsequently, 262 g of solvent at 60 ⁰ C and 120 mbar were removed in vacuo from 845 g of this product on a rotary evaporator. The solids resulted at 62.3% and the NCO content at 3.01%.

Example 8b: Comparative Polvovan Vanadium, containing nanoparticles

344.2 g of the product from Example 5 were initially charged in a standard stirring apparatus and treated with 955.8 g Organosilicasol from Example 3 within 30 min. The resulting modified polyisocyanate was transparent and had an NCO content of 1.8% by weight at a solids content of 37.1% by weight. The proportion of SiO ₂ nanoparticles in the dispersion was 22.1% by weight and in the solid 51% by weight. The product was clear and a little yellowish.

Then 374 g of solvent at 60 ⁰ C and 120 mbar were removed in vacuo from 895 g of this product on a rotary evaporator. The solids resulted at 65.0% and the NCO content at 3.13%. Example 9 Polvisocvanate According to the Invention Containing Nanoparticles

187.57 g of the product from Example 6a were initially charged in a standard stirring apparatus and admixed with 312.43 g Organosilicasol according to Example 3 within 30 min. The resulting modified, blocked polyisocyanate was liquid and transparent and had a blocked NCO content of 1.81 wt% at a solids content of 37.01 wt%. The proportion of SiO ₂ nanoparticles in the dispersion was 18.7% by weight and in the solid 50.6% by weight. The storage stability was> 3 months.

Example 10 Inventive Polyisocvanat containing nanoparticles

1487.5 g of the product from example 6 were initially charged in a standard stirring apparatus and 2512.48 g of Organosilicasol-MEK-ST (Nissan Chem. Corp.) were added over 30 minutes. The resulting modified blocked polyisocyanate was liquid and transparent and had a blocked NCO content of 1.74 weight percent at a solids content of 37.44 weight percent. The proportion of SiO ₂ nanoparticles in the dispersion was 18.8% by weight and in the solid was 50.4% by weight.

Example 11: Inventive Polvisocvanat containing nanoparticles

From 340.3 g of the product from Example 9 140.3 g of solvent were removed on a rotary evaporator at 60 ⁰ C and 120 mbar. The resulting nanoparticle-containing polyisocyanate was transparent and had a blocked NCO content of 3.18 wt .-% at a solids content of 67.1 wt .-%. The proportion of Si0 ₂ nanoparticles in the dispersion was 31.8 wt .-% and in the solid 50.6 wt .-%. The viscosity at 23 ⁰ C was 1620 mPas. The storage stability was> 3 months.

Example 12: Inventive Polvisocvanat containing nanoparticles

From 771.3 g of the product from Example 10 289 g of solvent were removed on a rotary evaporator at 60 ⁰ C and 120 mbar. The resulting nanoparticle-containing polyisocyanate was transparent and had a blocked NCO content of 2.86 wt .-% at a solids content of 61.5 wt .-%. The proportion of SiO 2 nanoparticles in the dispersion was 30.9% by weight and in the solid 50.4% by weight.

Example 13a-g Polvisocyanates according to the invention, containing nanoparticles

Analogously to Example 9, further polvocyanates according to the invention, containing nanoparticles, were prepared and, if appropriate, solvents were distilled off. Clear, liquid products were obtained.

Example 14: Comparative Polyisocyanate according to DE 10 2006 054289

In a standard stirred apparatus 453.6 g (1 eq) of Desmodur ^® N3300 submitted in 80 g of butyl acetate at room temperature and nitrogen was passed over with 2L / h. Then 186.5 g (0.2 eq) of the alkoxysilane from Example 1 in 80 g of butyl acetate were added dropwise within 3 h at room temperature.

This gave a colorless, liquid polyisocyanate having the following characteristics: solids content 80 wt .-%, 9.58% NCO content.

Example 15: siloxane-containing comparative polyisocyanate

In a standard stirred apparatus 492.1 g h of nitrogen (1 eq) of Desmodur ^® introduced into 250 g of butyl acetate at 80 ⁰ C N3300 and 2 l / transferred. Subsequently, 7.86 g (0.02 eq) was added the siloxane block copolyol from Example 2a at 80 ⁰ C and the temperature was held for 4 h. Of the theoretically expected NCO content was checked titrimetrically and then cooled to room temperature and added 250 g of butyl acetate.

A clear polyisocyanate with the following characteristics was obtained: solids content 50.3% by weight and 10.4% NCO content.

Example 16: Invention-essential silane and siloxane-modified PIC

hi a standard stirred apparatus (1 eq) of Desmodur ^® introduced into 250 g of butyl acetate at 80 ⁰ C 350.8 g N3300 and 2 l / h of nitrogen passed over. Subsequently, 5.60 g (0.02 eq) was added the siloxane block copolyol from Example 2a at 80 ⁰ C and the temperature was held for 4 h. The theoretically expected NCO content was checked titrimetrically and then cooled to room temperature. 143.6 g were within 3 h (0.2 eq) of the alkoxysilane from Example 1 and 250 g of butyl acetate, wherein the temperature was maintained by ice-cooling below 40 ^0C. After checking the theoretical NCO content was cooled to RT.

A clear, liquid polyisocyanate with the following characteristics was obtained: solids content 50.6% by weight and 5.75% NCO content.

Example 17: Comparative polyisocyanate containing nanoparticles

129.6 g of the product from Example 14 in 77.8 g of butyl acetate were initially charged in a standard stirring apparatus and admixed with 392.7 g of Organosilicasol ™ MEK-ST (Nissan Chemicals Corp.) within 30 minutes. The resulting nanoparticle-modified polyisocyanate was liquid and transparent and had an NCO content of 1.76 wt% at a solids content of 37.2 wt%. The proportion of SiO ₂ nanoparticles in the dispersion was 19.6% by weight and in the solid 53.2% by weight.

Example 18 Comparative Polyisocvanate, Containing Nanoparticles

136.3 g of the product from Example 15 were presented in a standard stirring apparatus and with

363.7 g Organosilicasol added according to Example 3 within 30 min. The resulting modified, blocked polyisocyanate was translucent and had an NCO content of 2.81% by weight at a solids content of 36.2% by weight and gelled after 1 day. The proportion of SiO ₂ nanoparticles in the dispersion was 21.8% by weight and in the solid 61% by weight.

Example 19 Polyisocyanate According to the Invention, Containing Nanoparticles

173.4 g of the product from Example 16 were initially charged in a standard stirring apparatus and mixed with 326.6 g Organosilicasol according to Example 3 within 30 min. The resulting modif ϊ The blocked, blocked polyisocyanate was transparent and had an NCO content of 1.94% by weight and a solids content of 37.5% by weight. The proportion of SiO ₂ nanoparticles in the dispersion was 19.6% by weight and in the solid 52.8% by weight. The storage stability until gelling was about 1 month.

Performance testing of the blocked polyisocyanates:

The polyisocyanate according to the invention of Example 9 was 17 ^® Desmophen A870 BA in the NCO / OH ratios of 1.0 and 0.1% Baysilone OL (solid / solid binder. 10% solution in MPA), 2.0% BYK 070 (LFF./BM fixed), 1.0% Tinuvin 123 (LFF./BM fixed), 1.5% Tinuvin 384-2 (LFF./BM fixed) and 0.5% DBTL (fixed / BM fixed), 10% solution in MPA) as paint additives and stirred well. The solids of the coatings were between 40 and 50% and were optionally adjusted with a solvent mixture MP A / SN 1: 1. Until processing, the paint was still 10 min. vented. The varnish was then applied to the prepared substrate using a gravity cup gun in 1.5 cloisters (3.0-3.5 bar compressed air, nozzle: 1.4-1.5 mm 0, nozzle-substrate distance: approx cm). After a drying time of 15 min. the paint was at 140 ⁰ C for 30 min. baked. The dry film thickness was 30-45 μm in each case. The results are summarized in Table 2.

For comparison, a conventional coating system comprising Desmophen ^® A 870 and Desmodur ^® VP LS 2253, and the Vergleichspolyisocyanaten from Examples 5 and 6 with paint additives (Table 1) was formulated and applied analogously. The results are also summarized in Table 2.

Table 2a Comparison of the coating properties, blocked polyisocyanates

O - good; 5 - bad

The blocked PIC containing SiO ₂ nanoparticles of Example 9 modified according to the invention shows improvements in solvent resistance, water resistance and dry and wet scratching in comparison to the modified polyisocyanates from Examples 5 and 6 and to the DMP-blocked polyisocyanate LS 2253 both before and after reflow. The other properties were preserved. In a further test series, aminosilane-modified, nanoparticle-containing polyisocyanates (DE 10 2006 054289) were compared with amino- and polysiloxane-modified, nanoparticle-containing polyisocyanates according to the invention. This was similar to the procedure described above. The curing took place with Desmophen A870 at an NCO ratio of 1: 1. However, with the aid of MPA / SN100 (1: 1), the coatings were adjusted to outlet viscosities of between 20 and 25 seconds and not to a solids content. This resulted in spray solids of 40 to 60%. Drying was carried out for 30 min at RT, then 30 min at 140 ⁰ C and then 16 h at 60 ⁰ C. The results are shown in Table 2b.

Table 2b Comparison of the coating properties of the blocked polyisocyanates according to the invention with the formulation from DE 10 2006 054289

The inventively modified, nanoparticle-containing polyisocyanate from Example 12 shows in the formulation used improved scratch resistance, pendulum hardness and flow, gloss and haze compared to the aminosilane-modified, nanoparticle-containing polyisocyanate according to DE 10 2006 054289 (Example 8a). By using the organosol from Example 3 according to Example 8b, the scratch resistance and pendulum hardness of the polyisocyanate according to DE 10 2006 054289 could indeed be significantly improved, but the level of the polyisocyanate according to the invention could not be achieved. In principle, dry scratch resistance and solvent resistance can be improved by the polyisocyanate according to the invention compared with the nanoparticle-free comparison.

Table 2c Comparison of the coating properties of the inventive blocked polyisocyanates, different siloxane block

According to the invention, nanoparticle-containing polyisocyanate shows a significantly increased scratch resistance and pendulum hardness compared to the standard.

Performance testing of unblocked polyisocyanates:

General conditions MMT 79-72 / 1, 2, 5, 6 and MMT 79-57 / 6:

A 870 BA, catalyst-free, 40-50% spray body content, 25 min at 140 ⁰ C + 16 h at 60 ⁰ C stoving clearcoat film thickness of 35-52 microns, clear varnishes, visually iO

Application testing

The polyisocyanate according to the invention from Examples 16 was Desmophen ^® A 870 BA in the NCO / OH ratios from 1: 0 mixed and paint additives (Table 3) and stirred well. The solids of the coatings were between 40 and 50% and were optionally adjusted with a solvent mixture MP A / SN 1: 1. Until processing, the paint was still 10 min. vented. The varnish was then applied with a flow cup gun in 1, 5 cloisters on the prepared Un- substrate (3.0-3.5 bar compressed air, nozzle: 1.4-1.5 mm 0, nozzle-substrate distance: approx. 20-30 cm). After a drying time of 15 min. the paint was at 140 ⁰ C for 25 min. baked. The dry film thickness was 30-45 μm in each case. After a conditioning / aging of 16 h at 60 ⁰ C, the paint inspection was started. The results are summarized in Table 4.

For comparison, a conventional coating system comprising Desmophen ^® A 870 and Desmodur ^® N 3390 and the modified nanoparticle-free polyisocyanates of Example 12 to 14 with paint additives (Table 3) was formulated and applied analogously. The results are also summarized in Table 4.

Table 3 Amounts Additives

Standard 2K PUR paints:

0.1% Baysilone OL 17 (solid / BM solid) used as a 10% solution in MPA

2.0% BYK 070 (LT / BM fixed)

1.0% Tinuvin 123 (Lff / BM fixed)

1, 5% Tinuvin 384-2 (Lff./BM fixed)

Table 4 Comparison of the coating properties, 2K, unblocked polyisocyanates

¹ - good; 5 - bad

The inventively modified polyisocyanate containing SiO ₂ nanoparticles from Example 18 shows improvements in water resistance and dry scratching, both before and after reflow compared to the pure polyisocyanate (standard 2K). The wet scratch before reflow was also improved. In comparison with DE 10 2006 054289 (Ex. 16), the solvent resistance and the pendulum hardness could be improved.

Claims

Pateπtansprüche:

1. A process for the preparation of nanoparticle-modified polyisocyanates, in which

A) polyisocyanates with

B) alkoxysilanes of the formula (I)

QZ-SiX ₃ Y _3-3 (I)

in which

Q is an isocyanate-reactive group,

X is a hydrolyzable group,

Y are identical or different alkyl groups

Z is a C 1 -C ₁₂ -alkylene group and

a is an integer from 1 to 3,

in which

X is an aliphatic, optionally branched Ci- to Cj ₀ -ReSt, preferably methyl,

Ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, tert-butyl, particularly preferably methyl or Si - [- [0-CH ₂ -CHZ] _n -O-] unit with Z = H or methyl, preferably H and n = 1 -

12, preferably 1 to 5 or very particularly preferably a [-CH ₂ -O- (CH ₂ ), -] - Si unit with r = 1 to 4, preferably with r = 3, R is a hydroxy-functional carboxylic acid ester of the formula

where x = 3 to 5, preferably 5,

or preferably a -CH (OH) Y group in which

Y is a -CH ₂ -N (R ² R ³ ) group, where

R ^{2 may be} H, methyl, ethyl, n-propyl, isopropyl, cyclohexyl, 2-hydroxyethyl, 2-hydroxypropyl, 3-hydroxypropyl, and R ^{3 is} 2-hydroxyethyl May be 2-hydroxypropyl, 3-hydroxypropyl,

R ^{1 may be} identical or different and is hydrogen or an optionally hetero atom-containing Cr to Ci ₀ hydrocarbon radical and n is 1 to 40

D) optionally blocking agents

be implemented, and subsequently

2. The method according to claim 1, characterized in that in A) polyisocyanates with uretdione, isocyanurate, allophanate, biuret, Iminooxadiazindion- and / or Oxadiazintrionstruktu- ren are used.

3. The method according to claim 1 or 2, characterized in that in A) polyisocyanates based on IPDI, MDI, TDI, HDI or mixtures thereof are used.

4. The method according to any one of claims 1 to 3, characterized in that in formula (I) the group X is an alkoxy or hydroxy group, Y is a linear or branched QC ₄ - alkyl group and Z is a linear or branched Ci-C ₄ alkylene group is, where a in formula (I) is 1 or 2 and the group Q is a group reacting with isocyanates under urethane, urea or thiourea formation.

5. The method according to any one of claims 1 to 4, characterized in that in B) compounds of the formula (I) alkoxysilyl-containing aspartic acid esters are used.

6. The method according to any one of claims 1 to 5, characterized in that in the hydroxyl-containing polysiloxanes of the formula (II) R is a hydroxy-functional carboxylic acid ester of the formula

where x = 3 to 5,

or a hydroxyalkyl-functional amino group of the formula

OH

.R '

in which

R ^{2 is} an aliphatic linear, branched or cyclic hydroxyalkyl radical and

R ^{3 is} hydrogen or according to the definition of the radical R ²

is.

7. The method according to any one of claims 1 to 6, characterized in that the hydroxyl-containing polydimethylsiloxanes of the formula (II) number average molecular weights of 250 to 2250 g / mol.

8. The method according to any one of claims 1 to 7, characterized in that the ratio of the NCO groups of the used in A) to be modified polyisocyanate to the NCO-reactive OH groups of the hydroxyl-containing polysiloxane of the formula (IT) 1: 0.001 to 1 : 0.4 and the ratio of the NCO groups of the polyisocyanate to be modified used in A) to the NCO-reactive groups Q of the alkoxysilane of the formula (I) is 1: 0.01 to 1: 0.75.

9. The method according to any one of claims 1 to 8, characterized in that in step D) the still free isocyanate groups are blocked.

10. The method according to any one of claims 1 to 9, characterized in that the nanoparticles are introduced in step E) in the form of dispersions in organic solvents.

11. The method according to claim 10, characterized in that are used as organic solvent alcohol and ketone-free solvent.

12. The method according to any one of claims 1 to 11, characterized in that are used as nanoparticles in step E) silica, alumina, cerium oxide, zirconium oxide, niobium oxide or titanium oxide, zinc oxide.

13. The method according to any one of claims 1 to 12, characterized in that the nanoparticles used in E) are surface-modified.

14. Nanoparticle-modified polyisocyanates obtainable by a process according to one of claims 1 to 13.

15. polyurethane systems comprising nanoparticle-modified polyisocyanates according to claim 14.

16. Coatings, bonds or moldings obtainable using the polyurethane systems according to claim 15.