DE102009040868A1 - Lacquer system, useful for producing coatings on plastics, preferably polycarbonate, polymethylmethacrylate or polyethylene terephthalate, comprises aqueous adhesive dispersion made of polymer, organic binder and hetero-coagulate - Google Patents

Abstract

Lacquer system comprises an aqueous adhesive dispersion made of polymer, organic binder and hetero-coagulate, where the hetero-coagulate is formed by the functional nanoparticles and secondary nanoparticles.

Description

The present invention relates to a coating system comprising an aqueous binder dispersion of polymeric, organic binders and heterocoagulates, wherein the heterocoagulates are formed by functional nanoparticles and secondary nanoparticles. Another object of the invention is the use of the coating system for the production of coatings.

Paints, such as B. for wood preservation applications (parquet, furniture, etc.), used in the automotive sector or for coating plastics, should often have additional functionalities in addition to the surface protection. These include properties such. As UV or IR protection, higher scratch resistance, color, electrical or magnetic properties or increased chemical resistance.

For this purpose u. a. the addition of certain particulate organic, but especially inorganic fillers proposed to fulfill this function long-term stability. By adding these materials, however, depending on the particle size and their material properties, such as. As the refractive index, the transparency of the paint greatly reduced or its Haze be increased.

As one skilled in the art knows, since the haze of a lacquer at a constant mass-based fill level decreases as the particle size of the particulate filler decreases, nanoscale particles of the desired material are used to achieve the desired properties of the lacquer while maintaining its transparency. However, the nanoparticles must be sufficiently dispersed in the cured coating in order not to increase the degree of turbidity again by unintentional agglomeration of the nanoparticles.

The limit above which a turbidity induced by the filler has a disturbing effect depends crucially on the field of application, but it should usually be as small as possible. In order to ensure that the tolerable for the particular field of application opacity of the paint is not exceeded, necessary for the required distribution of the particles in the paint dispersion (effort for surface modification and mechanical dispersion) and thus the cost is usually very high and the result still often unsatisfactory.

Nanoparticles in polymeric coatings can specifically improve properties such as scratch resistance, UV protection, conductivity, etc. The literature assumes that the control of surface modification and dispersion of the nanoparticles determines the required transparent appearance of the coatings and their properties. ( Nanoparticle composites for coating applications. Cayton, Roger H. Editor (s): Laudon, Matthew; Romanowicz, Bart., NSTI Nanotech 2004, Boston, MA, United States, Mar. 7-11, (2004), 3 312-315 .). In general, it is postulated that extensive deagglomeration in combination with small particle sizes leads to transparent coatings.

It would be desirable if an incorporation of functional inorganic particles could be carried out without costly surface modification.

Usually, the nanoparticles are dispersed in practice in the resin component, in the aqueous phase or in the finished mixture of hardener and resin just before curing. As a rule, it is necessary to adapt the surface of the nanoparticles to the specific matrix of the coating agent or of the adhesive. Disadvantage of simple incorporation of modified nanoparticles is the dependence of the stability of the complete formulation, d. H. from all formulation ingredients. The variation of one parameter can lead to segregation here (Pilotek, Steffen, Tabellion, Frank (2005), European Coatings Journal, 4, 170ff).

It is known that inorganic materials such. B. TiO ₂ , ZnO or CeO ₂ UV-absorbing properties and are already used for this purpose in paints. If the intrinsic color of the lacquer does not interfere with the application, it is also possible to use iron oxides or other UV-light-absorbing and / or coloring materials. A disadvantage of such paints, however, is that the introduction of the fillers often leads to an unwanted turbidity of the paint or a very high cost for a good distribution of the particles in the paint must be driven without significant agglomeration. The latter is a problem especially for economic reasons for many applications.

It is also known that pigments which are to be used for UV protection, by targeted assembly with a second material with a lower refractive index, a significant reduction of Clouding the entire matrix. So be in the WO 96/28137 and in the WO 95/09895 Inorganic pigmented emulsions of UV-protecting particles for cosmetic applications provided by this technique. Stable aqueous heterocoagulate dispersions and aqueous coating raw material dispersions containing corresponding heterocoagulates which give transparent coating films or adhesions are not described.

In US 6565973 Hetero coagulants have been prepared by the assembly of IR-absorbing or colored pigments, which can be used for IR protection and coloring in plastics and paints. There, the incorporation of powdered heterocoagulates in solvent-based paints is described by grinding processes. Not described are stable aqueous Heterokoagulatdispersionen and aqueous Lackrohstoffdispersionen containing appropriate heterocoagulates, which are characterized by their ease of processing and storage stability and give transparent coating films with improved mechanical and optical properties.

In the German patent applications DE 10 2007 061 875.3 and DE 10 2007 061 876.1 nanoparticle-containing binder dispersions are described for improving the scratch resistance. Nanoparticles of a variety are used whose dispersion in the coating matrix is crucial in order to achieve transparency. It is necessary to modify both the binder and the nanoparticle surface to achieve this goal.

It thus arises, starting from the prior art, the object of the invention to provide coating systems with improved optical and / or mechanical properties that do not have the disadvantages of the prior art and with low dispersing and without a complex surface modification of the particles required is high levels of functional nanoparticles and still have a slight haze of the paint films.

• A. Wässrige Bindemitteldispersion aus polymeren, organischen Bindemitteln und
• B. Heterokoagulate, die von funktionellen Nanoteilchen und Neben-Nanoteilchen gebildet werden.

gelöst.This object is achieved by paint systems

• A. Aqueous binder dispersion of polymeric, organic binders and
• B. heterocoagulates formed by functional nanoparticles and minor nanoparticles.

solved.

It has thus been found that transparent coatings can also be obtained starting from aqueous dispersions by using refractive index-adapted heterocoagulates. The aqueous heterocoagulate dispersions or the aqueous coating dispersions show a surprising stability and can therefore easily be used for the production of transparent coating films. With appropriate selection of the functional nanoparticles contained, films with improved mechanical properties can be obtained.

Suitable polymeric, organic binders A are aqueous, organic dispersions commonly used in coatings and adhesives. For example, these are polyacrylate dispersions, polyurethane dispersions, polyester-polyacrylate dispersions, polyester-polyurethane dispersions.

A heterocoagulate (B) is an agglomerate that is produced by targeted assembly of different types of nanoparticles (functional nanoparticles and suitable minor nanoparticles), the functional nanoparticles possibly being present as primary particles. These must not or only in small proportions be present in a homocoupulated manner, whereby the small proportions of homocoagulated functional nanoparticles in the heterocoagulate should be arranged spatially as far apart as possible and distributed as far as possible evenly.

The size of the primary particles or homocoagulated portions of the functional nanoparticles should be less than 50 nm, preferably less than 20 nm and particularly preferably less than 10 nm.

The composition of the heterocoagulates can be determined by means of the theories of the effective medium (eg Garnett, Bruggemann, Looyenga, etc .; See also U. Kreibig, M. Vollmer: In "Optical Properties of Metal Clusters", Springer Series in Materials Science, Springer-Verlag Berlin, Heidelberg 1995; Cape. 2.3, pp. 123-186 ) be calculated. It depends on the dielectric constants or refractive indices of the functional nanoparticles, the minor nanoparticles and the surrounding matrix. The volume fraction f of the functional nanoparticles in the total volume of the two-component heterocoagulate (ie Total volume of functional nanoparticles plus minor nanoparticles) such that the following inequality is satisfied:

In this case, ε = ε (λ) is the wavelength-dependent, complex dielectric constant of the surrounding paint _matrix (ε _matrix ), the secondary nanoparticles (ε secondary _{nanoparticles} ) and the functional nanoparticles (ε _{nanoparticles} ).

It is generally true that the complex, wavelength-dependent dielectric constant ε = ε (λ) is related to the complex, wavelength-dependent refractive index n = n (λ) via the relationship ε = n ² . For this reason, the volume fraction f of the functional nanoparticles in the total volume of the heterocoagulate (ie total volume of functional nanoparticles plus secondary nanoparticles) must be chosen in such a way that the following inequality is fulfilled:

In this case, y <0.2, preferably <0.1, particularly preferably <0.02 and very particularly preferably <0.005, in order to achieve an optimum result, ie. H. a slight haze of the paint according to the invention to achieve.

For example, for a coating according to the invention whose organic matrix has a refractive index of 1.505 and contains heterocoagulates of CeO ₂ as functional nanoparticles and SiO ₂ as minor nanoparticles, an optimum result is achieved with a 5% by volume of functional nanoparticles in the entire inorganic heterocoagulate.

In otherwise identical components of the paint according to the invention is obtained using ZnO instead of CeO ₂ with a volume fraction of 7% and in Al ₂ O ₃ with a volume fraction of 13% in the inorganic heterocoagulate an optimal result.

The heterocoagulates thus provided have a mean refractive index which coincides with that of the surrounding resist matrix within the limits given by y. Since the functional nanoparticles usually have a higher refractive index, a correspondingly smaller refractive index is required for the minor nanoparticles.

Mostly, SiO ₂ is suitable as minor nanoparticles. But it can also other materials with low refractive index such. As alkali or alkaline earth fluorides or nanoporous, gas-containing materials are used as minor nanoparticles.

As a result of this refractive index adaptation of the heterocoagulates, it is no longer necessary to disperse the functional nanoparticles nanoparticulate with great effort in the coating matrix. Instead, the larger refractive index-matched heterocoagulates containing the functional nanoparticles can be incorporated by simple means.

The use of heterocoagulates as an additive in a paint formulation achieves the desired effect of nanoparticles and in particular ensures the high transparency of the paint. However, handling is similar to that of micro or sub-microparticles. The size of the heterocoagulates in the paint is in principle no restrictions in the case of an ideal adaptation of the refractive index.

Since small deviations from the ideal composition often occur in practice, to ensure high transparency, the heterocoagulates should preferably be smaller than 1 μm, more preferably smaller than 300 nm and most preferably smaller than 100 nm. A limitation of the size of the heterocoagulates proves to be useful depending on the used paint matrix to a good processability z. B. respect. To ensure the viscosity.

The volume concentration of heterocoagulates C _HK in the dried varnish depends on the volume concentration of functional nanoparticles (C _FN ) to be used for the respective application and should be selected according to the following equation: C _HK = C _FN / f

If, for example, a lacquer according to the invention whose organic matrix has a refractive index of 1.505 is to be provided with a CeO ₂ volume concentration of C _FN = 1% (corresponding to a CeO ₂ mass concentration of about 9%), this lacquer contains because of the volume fraction on CeO ₂ of f = 5% in the heterocoagulate a volume fraction of C _HK = 20% heterocoagulate. This corresponds to assuming that the organic portion of the varnish has a density of 1.15 g / cm ³ , a mass fraction of about 35%.

In order to utilize the advantageous properties of the lacquer according to the invention with respect to the mechanical and chemical stability, C _HK should be between 0.5% by volume and 50% by volume, preferably between 5% by volume and 40% by volume and particularly preferably between 10% by volume and 35% by volume. and most preferably between 15% by volume and 30% by volume. At high degrees of filling of more than 10% by volume, the boundaries between the individual heterocoagulates can come into contact in the dried and / or crosslinked lacquer. However, this case does not change the properties or the production of the paint according to the invention.

In a preferred embodiment of the invention, the functional nanoparticles may also be enveloped by the minor nanoparticles as a particulate layer or by the material of the minor nanoparticles as a continuous layer. A continuous coating can completely or partially envelop the functional nanoparticles. The particulate or continuous layer can also be made of a different material as long as the total refractive index of the heterocoagulate remains within the limits given by y.

In a further preferred embodiment of the invention, the functional nanoparticles and minor nanoparticles may also be present as a non-compact heterocoagulate which is permeated by the organic matrix of the varnish. The organic matrix may be present as a discontinuous or else as a continuous phase. In the case where the organic matrix is present as a continuous phase in the heterocoagulate, this means that the functional nanoparticles and minor nanoparticles may not be in direct contact with each other. In the case of a non-compact heterocoagulate having the organic matrix as the continuous phase, the functional nanoparticles and minor nanoparticles may be in groups or evenly distributed. If they are present in groups, such a group can be regarded as an at least three-component heterocoagulate whose mean refractive index must be matched to that of the organic matrix.

Depending on the choice of functional nanoparticles, the paint of the invention receives z. B. UV protecting properties (eg, for TiO ₂ , CeO ₂ , ZnO or iron oxides), NIR light absorbing properties (eg, ITO or LaB ₆ ), magnetic properties (eg, magnetite , Maghemite), improved mechanical properties (eg Al ₂ O ₃ , ZrO ₂ ).

The list can be continued here by any other types of nanoparticles, by the introduction of which the person skilled in the art would like to expand or modify the property spectrum of the coating system. The list is therefore not exhaustive and reflects the possibilities only as an example.

In part, combined properties can be achieved using certain particle types or suitable combinations of functional nanoparticles. As an important additional benefit because of the high solids content, the mechanical properties of the paint such. B. module, energy consumption or scratch resistance changed advantageous. In addition, it was found that the chemical and solvent resistance of the paint according to the invention was increased.

The preparation of the heterocoagulates as essential constituents of the paint according to the invention takes place for. By electrostatic attraction of the functional nanoparticles and minor nanoparticles in an aqueous environment. For this purpose, a pH must be chosen for the process of heterocoagulation, in which both components have a different polarity of the surface charge, i. H. have a different sign in the zeta potential. It is irrelevant whether the different polarity when merging the nano-particle types is already present or thereafter by shifting the pH.

In order to avoid homocoagulation as far as possible, the process of heterocoagulation can preferably be supported by introduction of mechanical energy (eg with the aid of stirring tools, ultrasound, homogenizers, microfluidizers, jet dispersers).

In a preferred embodiment of the invention, the surface charge of a nanoparticle component can be modified or enhanced by adding anions or cations. These ions may be in the form of salts such. As acetates, nitrates, sulfates, phosphates or in the form of hydrophilic polymers such. As hydrophilic linear or branched homopolymers or copolymers, with functional groups such as amino, carboxyl, or their salts, hydroxyl, thiol, acid anhydrides, acid chlorides and / or isocyanate groups are added. The functional, possibly also adsorptive groups of the corresponding polymers can be in the repeating unit, such as in polyacids, polyacids, polyalcohols, polythiols or polyamines or polyheterocycles, so in the case of polyacrylic acid and / or their salts, polymethacrylic acid and / or their Salts, poly (meth) acrylamides, polymaleic acid and / or salts thereof, polyaspartic acid and / or salts thereof, polymaleic anhydrides, polyethyleneimines, polyhydroxyethyl methacrylates (PHEMA), polydimethylaminoethyl methacrylates and / or its salts, polyvinylpyrrolidones, polyvinyl alcohols, polyvinyl acetal or Polyvinyl ether or the polyether.

Suitable aminic polymers include, for example, polyallylamine, polyvinylamine, linear or branched polyethyleneimines, polylysine, polymers containing chitosamines and also polydiallyldimethylammonium chloride and / or polyvinylpyridine or their acid adducts as homopolymers or copolymers. All named polymers can be used for the preparation of the nanoparticles as homopolymers or else as copolymers with one another and with other monomers. Also conceivable are copolymers of acrylic acid with vinylpyrrolidone, maleic anhydride with methyl vinyl ether, vinylpyrrolidone with dimethylaminoethyl methacrylate, vinylimidazole with vinylpyrrolidone and methacrylic acid with vinylpyrrolidone.

Further suitable polymers are those whose functional groups are located in the end groups, such as in the case of amino / carboxy / thio / isocyanate or other endgruppenfunktionalisierten polyether, such. B. in amino-functional oligo- or polyethylene glycols (Jeffamine) or OH-terminated polyethylene oxides.

Preference is given to polymers having functional groups in the repeat unit, particularly preferably the polyacids, and very particularly preferably polyacrylic acids or polymethacrylic acids and / or salts thereof.

In a further embodiment, it is also possible to use reactive polymers, such as polymaleic anhydrides or polysuccinimides, which in the course of further processing react to form the abovementioned polyelectrolytes, namely polyacrylic acid or polyaspartic acid.

In a preferred embodiment, the shell of the nanoparticles contains polyacrylic acid, polymethacrylic acid, polyaspartic acid (PASP), polymaleic acid, copolymers of acrylic acid, for example. with maleic acid, which are sold under the product name Sokalan® ^® by the company BASF and / or copolymers of acrylic acid with maleic acid and vinyl ether, available from the firm SKW Polymers under the name Melpers ^®, and / or their salts, preferably their sodium salts.

The molecular weight of the polymers of the shell of the nanoparticles can be variable, preferably it is at an M _w of 500 to 50,000 gmol ^-1 , preferably between 1000 and 10,000 gmol ^-1 and more preferably between 1500 and 5000 gmol ^-1 .

In addition to the above-mentioned reasons, the polymers listed can also be used to stabilize the heterocoagulates in order to reduce their average size for further processing to below 5 .mu.m, preferably below 1 .mu.m, more preferably below 500 nm and most preferably below 100 nm. This reduction may assist in the further processing of the lacquers containing the heterocoagulates of the invention.

The excess of stabilizing ions and polymers must be separated from the heterocoagulates, since this can lead to a reduction in the transparency of the subsequently produced paint during further processing. This can be z. B. by dialysis, centrifugation, membrane filtration or ion exchangers can be achieved.

Particular preference is given to using particles which have not been surface-modified with polymers or silanes.

Examples:

Example 1a: Preparation of the heterocoagulates with stabilizing polymer

613.3 g of Levasil 200 dispersion (aqueous silica dispersion, H. C Starck GmbH, Leverkusen, D) with w (SiO 2) = 0.05 was treated with conc. HNO3 adjusted to pH 3. Subsequently, first 153.3 g of CeO 2 dispersion (aqueous cerium oxide dispersion essigsauer, Nyacol Corp. USA) with w (CeO 2) = 0.05 to the levasil dispersion and then 47.9 g PAS2000 solution (w (PAS2000) = 0 , 05, sodium salt of polyacrylic acid, molecular weight 2000, Fluka (manufacturer), SIGMA-ALDRICH Vertriebs GmbH).

Add with stirring and 2 min. stirred with a magnetic stirrer. This mixture is adjusted to pH 9 with 2-dimethylethanolamine and stirred for a further 5 min. To separate excess salts and polyacrylic acid, the mixture was centrifuged for 2.5 hours at 25,000 rpm. The supernatant was discarded and the sediment redispersed with deionized water. This process was repeated twice. Finally, all sediments were combined and redispersed in about 50 mL of water. The solids content of the resulting dispersion was 20.3% by weight.

Example 1b: Preparation of the heterocoagulates without stabilizing polymer

276 g Levasil 200 w (SiO ₂ ) = 0.1 was treated with conc. HNO ₃ to pH. 3 Subsequently, 69 g of CeO ₂ dispersion (aqueous cerium oxide dispersion essigsauer, Nyacol Corp. USA) with w (CeO ₂ ) = 0.1 with stirring by means of Ultraturrax at 21500 U / min within 5 min. dropwise. Thereafter, another 5 min. stirred (pH 3.8). The mixture was centrifuged in the centrifuge for 20 min. centrifuged at 10,000 rpm for a long time. The clear supernatant was separated and the sediment in about 300 mL sodium hydroxide, c (NaOH) = 0.1 mol / L, redispersed by means of ultrasonic fingers (pH 11.3). Thereafter, the mixture was 40 min. centrifuged at 10,000 rpm for a long time. The slightly turbid supernatant was discarded completely, the sediment redispersed in 300 ml of water (pH 10) and again for 120 min. centrifuged at 10,000 rpm for a long time. The cloudy supernatant was again discarded and the sediment redispersed in water. The solids content of the resulting dispersion was 23.9%.

Example 2a: Heterocoagulate-free lacquer

9.68 g of Bayhydrol XP 2645 (OH-containing polyacrylate dispersion, Bayer MaterialScience AG, Leverkusen, D) was mixed with 0.48 g of butoxyl and 7.34 g of deionized water and then mixed with 2.5 g of Bayhydur XP 2655 (hydrophilic polyisocyanate, Bayer MaterialScience AG, Leverkusen, D). The NCO / OH ratio was 1.8. Subsequently, with the aid of a doctor blade, 240 μm wet layer thickness was applied to a glass plate and cured at 60 ° C. for 30 minutes. A clear film was received.

Example 2b: Lacquer with 30% (w) of inorganic component from Example 1a

28.8 g of Bayhydrol XP 2645 (OH-containing polyacrylate dispersion, Bayer MaterialScience AG, Leverkusen, D) were briefly stirred in a vessel with 17.1 g of heterocoagulate from Example 1a. In another vessel, 5.1 g of Bayhydur XP 2655 was stirred with 1.0 g of butoxyl. Subsequently, the Bayhydur solution was added to the polyol component Bayhydrol XP 2645 with stirring with a Meiser disc at 2000 rpm. Thereafter, it was stirred for at least 1 minute with the Meiser disc at 2000 rpm. The batch was degassed in an ultrasonic bath for about 5 min. The degassed coating was applied with a 200 μm doctor blade and dried in the air for 60 minutes, then at 60 ° C. for 30 minutes. The resulting paint showed a high gloss and a very high, haze-free transparency.

Example 2c: Lacquer containing inorganic component from Example 1b

8.71 g of Bayhydrol XP 2645 (OH-containing polyacrylate dispersion, Bayer MaterialScience AG, Leverkusen, D) was mixed with 0.44 g of butoxyl, 6.43 g of deionized water and 2.17 g of a Heterokoagulatdispersion from Example 1b and then with 2 , 5 g Bayhydur XP 2655 mixed.

• ¹Werte aus Mikrohärtemessung entsprechend DIN EN ISO 14577

The NCO / OH ratio was 1.8. Subsequently, with the aid of a doctor blade, 240 μm wet layer thickness was applied to a glass plate and cured at 60 ° C. for 30 minutes. The content of inorganic heterocoagulate in the cured film was about 30 wt .-%. A clear film was received. Table 1 According to the invention 2b Ex. According to the invention 2c Example Comp. Ex. 2a ¹ surface hardness [N / mm ² ] 221 306 211 ¹ depth hardness [N / mm ² ] 172 206 152 ¹ penetration module [GPa] 3.9 4.2 3

• ¹ values corresponding to microhardness measurement DIN EN ISO 14577

As can be seen from Table 1, coatings of dispersions according to the invention containing heterocoagulates show improved mechanical properties. Stabilization of the heterocoagulates for better transparency was not required (see Examples 1a and 1b). The unmodified heterocoagulates from Example 1b (Example 2c lacquer) showed even better results in terms of hardness and penetration modulus.

Comparative Example 1a: Lacquer with pure CeO ₂

168 g of CeO ₂ dispersion (Nyacol, acetic acid) with w (CeO ₂ ) = 0.2 was vigorously shaken in a bottle with 168 g of PAS2000 solution (w (PAS2000) = 0.1) and then mixed with 2-dimethlyaminoethanol pH 9 adjusted. This mixture was centrifuged for two hours at 25,000 rpm. The supernatant was discarded and the sediment redispersed in water. The centrifugation procedure was repeated twice. The sediments were then combined and redispersed in about 30 ml of water. The solids content was 12.7% CeO ₂ .

15.9 g of the CeO ₂ dispersion were added to 15.0 g of Bayhydrol XP 2645 (OH-containing polyacrylate dispersion, Bayer MaterialScience AG, Leverkusen, D) and homogenized with the Meiser disc (about 700 rpm). Separately, 2.65 g Bayhydur XP 2570 was stirred with 0.52 g butoxyl (by hand). The isocyanate solution was added to the polyol component with stirring with the Meiser disc at 2000 rpm and stirred for 2 mm at this speed. The varnish was knife-coated onto a glass plate with a 200 μm doctor blade and dried at RT for 45 min, then at 60 ° C. for 30 min.

Although the resulting varnish showed a high gloss, its transparency was affected by a not negligible haze.

Comparative Example 1b: Lacquer with pure SiO 2 (levasil) → gelling, film turbidity

90.63 g of Bayhydrol XP 2645 (OH-containing polyacrylate dispersion, Bayer MaterialScience AG, Leverkusen, D) was mixed with 109.37 g of silica dispersion Levasil 300 (30% strength in water, H.C. Starck, Leverkusen). The dispersion had a solids content of 33.4 weight percent and an OH content of 0.54 weight percent. After storage for 2 days at room temperature, this dispersion repaid.

13.53 g of the freshly prepared mixture was mixed with 4.91 g of water and 1.56 g of Bayhydur 3100 (hydrophilic polyisocyanate, NCO content 17.4%, viscosity 2800 mPas at 23 ° C., Bayer MaterialScience AG, Leverkusen). The NCO / OH ratio was 1.5. Subsequently, using a doctor blade, 240 μm wet layer thickness was applied to a glass plate and cured at 60 ° C. for 30 mm. The content of inorganic SiO ₂ in the cured film was about 50% solid. The coating showed a strong haze.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• WO 96/28137 [0010]
• WO 95/09895 [0010]
• US 6565973 [0011]
• DE 102007061875 [0012]
• DE 102007061876 [0012]

Cited non-patent literature

• Nanoparticle composites for coating applications. Cayton, Roger H. Editor (s): Laudon, Matthew; Romanowicz, Bart., NSTI Nanotech 2004, Boston, MA, United States, Mar. 7-11, (2004), 3 312-315 [0006]
• Garnett, Bruggemann, Looyenga, etc .; See also U. Kreibig, M. Vollmer: In "Optical Properties of Metal Clusters", Springer Series in Materials Science, Springer-Verlag Berlin, Heidelberg 1995; Cape. 2.3, pp. 123-186 [0019]
• DIN EN ISO 14577 [0056]

Claims (13)

Paint system containing an aqueous binder dispersion of polymeric, organic binders and heterocoagulates, wherein the heterocoagulates of functional nanoparticles and minor nanoparticles are formed. The paint system of claim 1, wherein the heterocoagulates contain at least one inorganic component. Paint system according to one of claims 1 or 2, wherein the binder is a one- or a two-component polyurethane system. A coating system according to any one of claims 1 to 3, wherein the heterocoagulates have a composition with a mean refractive index difference which is less than 0.2, preferably less than 0.1, more preferably less than 0.02, and most preferably less than 0.005. Coating system according to one of claims 1 to 4, wherein the functional nanoparticles are present in the heterocoagulate or only in small proportions homocoupulated, and the individual functional nanoparticles or in small proportions homocoagulated functional nanoparticles in the heterocoagulate spatially as far apart as possible and widely distributed evenly distributed , The paint system of any one of claims 1 to 5, wherein the size of the functional nanoparticles or the homocoagulated portion of the functional nanoparticles in the heterocoagulates is less than 50 nm, preferably less than 20 nm and more preferably less than 10 nm. Paint system according to one of claims 1 to 6, wherein the heterocoagulates are less than 1 micron, preferably less than 300 nm and more preferably less than 100 nm. Paint system according to one of claims 1 to 7, wherein the heterocoagulates are present together with other polymers. Paint system according to one of claims 1 to 8, wherein the volume fraction of heterocoagulate in the paint system between 0.5 vol% and 50 vol%, preferably between 5 vol% and 40 vol% and more preferably between 10 vol% and 35 vol% and very particularly is preferably between 15% by volume and 30% by volume. A paint system according to any one of claims 1 to 9, wherein in the heterocoagulate the functional nanoparticles are completely or partially enveloped by the minor nanoparticles as a particulate layer or by the material of the minor nanoparticles as a continuous layer. Paint system according to one of claims 1 to 10, wherein the functional nanoparticles of oxides, in particular TiO ₂ , CeO ₂ , ZnO, Al ₂ O ₃ , magnetite, maghemite, doped oxides, in particular In ₂ O ₃ : Sn, SnO ₂ : Sb, ZnO: Al, SnO: F, borides, in particular LaB ₆ , and / or metals, in particular Au, Ag, Cu, Pt. Paint system according to one of claims 1 to 11, wherein the minor nanoparticles of silica, fluorine-containing compounds, in particular alkali or alkaline earth fluorides, and / or consist of gas-containing nanoporous materials. Use of a coating system according to one of claims 1 to 12 for the production of coatings, in particular on plastics, particularly preferably on polycarbonate, PMMA or PET.