EP2019848A1 - Nanoparticles - Google Patents

Abstract

The invention relates to nanoparticles, more particularly surface-modified nanoparticles, having an average particle size as determined by means of particle correlation spectroscopy (PCS) or the transmission electron microscope in the range from 3 to 50 nm, in dispersion in an organic solvent, characterized in that they are obtainable by a process in which one or more precursors of the nanoparticles are reacted in an organic solvent with a compound M3-x[O3(-)xSiR1-x] to give the nanoparticles, x being an integer selected from 0, 1 or 2, M being H, Li, Na or K, and all radicals R, in each case independently of one another, being a branched or unbranched, saturated or unsaturated hydrocarbon radical having 1 to 28 C atoms, in which one or more C atoms may have been replaced by O, and also to their use for UV protection in polymers.

Description

 nanoparticles

The invention relates to nanoparticles, in particular surface-modified nanoparticles, to a production method for such particles and to their use for UV protection.

The incorporation of inorganic nanoparticles in a polymer matrix can not only the mechanical properties, such. Impact resistance, of the matrix, but also changes their optical properties, e.g. wavelength-dependent transmission, color (absorption spectrum) and refractive index. In blends for optical applications, particle size plays an important role, since the addition of a substance with a refractive index which differs from the refractive index of the matrix, inevitably leads to light scattering and ultimately to opacity. The decrease in the intensity of radiation of a defined wavelength when passing through a mixture shows a strong dependence on the diameter of the inorganic particles.

In addition, many polymers are sensitive to UV radiation, so the polymers must be UV stabilized for practical use. Unfortunately, many organic UV filters, which would in principle be suitable as stabilizers, are themselves not photostable, so that there is still a need for suitable materials for long-term applications.

Accordingly, suitable substances would have to absorb in the UV range, appear as transparent and colorless as possible in the visible range, and be readily incorporated into polymers. Although numerous metal oxides absorb UV light, for the reasons mentioned above, they are poorly soluble without adversely affecting the mechanical properties or the optical properties in the visible light range into polymers.

The development of suitable nanomaterials for dispersion in polymers requires not only the control of particle size but also the surface properties of the particles. Simply mixing (e.g., by extrusion) hydrophilic particles with a hydrophobic polymer matrix results in uneven distribution of the particles throughout the polymer and also in their aggregation. For the homogeneous incorporation of inorganic particles into polymers, their surface must therefore be at least hydrophobically changed. In addition, in particular, the nanoparticulate materials show a great tendency to form agglomerates, which remain even with a subsequent surface treatment.

There are various approaches in the literature to provide suitable particles:

In International Patent Application WO 2005/070820, polymer-modified nanoparticles which act as UV stabilizers in

Polymers are described. These particles can pass through

Process in which in a step a) an inverse emulsion containing one or more water-soluble precursors for the

Nanoparticles or a melt, with the aid of a random copolymer of at least one monomer with hydrophobic radicals and at least one monomer with hydrophilic radicals is prepared and in a step b) particles are produced, can be obtained.

Preferably, these particles are ZnO particles having a particle size of 30 to 50 nm with a coating of a copolymer consisting essentially of lauryl methacrylate

(LMA) and hydroxyethyl methacrylate (HEMA). The are made ZnO particles, for example, by basic precipitation from an aqueous zinc acetate solution.

International patent application WO 2000/050503 describes a process for the preparation of zinc oxide gels by basic hydrolysis of at least one zinc compound in alcohol or an alcohol-water mixture, which comprises ripening the precipitate initially formed during the hydrolysis until the zinc oxide is completely flocculated, this precipitate is then compressed into a gel and separated from the supernatant phase.

International patent application WO 2005/037925 describes the production of ZnO and ZnS nanoparticles which are suitable for producing luminescent plastics. The ZnO particles are precipitated from an ethanolic solution of zinc acetate using ethanolic NaOH solution and allowed to age for 24 hours before replacing the ethanol with butanediol monoacrylate.

International patent application WO 2004/106237 describes a process for the preparation of zinc oxide particles in which a methanolic solution of zinc-carboxylic acid salts having a zinc ion concentration of 0.01 to 5 mol of Zn per kg of solution with a methanolic potassium hydroxide solution with a Hydroxidionen- concentration of 1 to 10 moles of OH per kg of solution in a molar ratio of OH to Zn of 1, 5 to 1, 8 is added with stirring and the precipitate solution obtained after completion of the addition at a temperature of 40 to 65 ⁰ C. Matured over a period of 5 to 50 min and finally cooled down to a temperature of <25 ° C. This gives particles that are almost spherical. - A -

The dissertation by K. Feddern ("Synthesis and optical properties of ZnO nanocrystals", University of Hamburg, June 2002) describes the preparation of ZnO particles from zinc acetate by means of LiOH in isopropanol, whereby the particles can be used similar to the so-called "Stöber process "are coated by reaction with tetraethoxysilane in the presence of ammonia with SiO ₂ , but form cloudy dispersions. The coating of dispersed ZnO particles with ortho-phosphate or tributyl phosphate or diisooctylphosphinic acid is also described here.

German patent applications DE 102005056621 and DE 102005056622 describe production processes for nanoparticles in which one or more precursors for the nanoparticles in an organic solvent are converted to the nanoparticles in a step a), and in a step b) the growth of the nanoparticles by addition at least one modifier, which may be a copolymer of at least one monomer having hydrophobic radicals and at least one monomer having hydrophilic radicals or an alkoxysilane, is terminated when, in the UV / VIS spectrum of the reaction solution, the absorption edge has reached the desired value, and its use for UV protection in polymers.

There is still a need for suitable surface modifications for nanoparticles and manufacturing processes that allow for the precise adjustment of the absorption and scattering behavior and the control of the particle size.

It would be desirable, therefore, a method with which it succeeds small

Produce nanoparticles directly with a suitable surface modification as possible agglomerate-free, the particles thus obtained in dispersions in the UV absorb radiation, but in Visible area hardly absorb radiation or scatter and are stable in this state for a long time.

Now it has surprisingly been found that this is possible in one step, when the particle formation and surface modification is triggered by a siloxy compound.

A first subject of the present invention are therefore nanoparticles with an average particle size determined by means of particle correlation spectroscopy (PCS) in the range of 3 to 50 nm, dispersed in an organic solvent, characterized in that they are obtainable by a process in which one or more precursors for the nanoparticles in an organic solvent with a compound M _3-x [θ _3-x SiRi + χ] are converted to the nanoparticles, where x is an integer selected from 0, 1 or 2, M is H, Li , Na or K and all R independently of one another represent a branched or unbranched, saturated or unsaturated hydrocarbon radical having 1 to 28 C atoms in which one or more C atoms may be replaced by O.

The particles according to the invention are distinguished by high absorption in the UV range, particularly preferably in the UV-A range, combined with high transparency in the visible range. In contrast to many particle qualities known from the prior art, these properties of the particles according to the invention do not change during storage or only to a negligible extent.

In addition, the SiRi _{+ x} groups on the particle surface reduce the photocatalytic activity of the particles or their photocatalytic degradation. In a preferred embodiment of present invention, in particular after modification of the particles by further layers, the photocatalytic activity of the particles is significantly reduced (as shown in Example 4).

Moreover, the production process according to the invention allows economical production of the particles, since higher solids contents can be achieved in the product suspension than using the customary hydroxide bases. By adding the compound M _3-x [O _3-x SiRi _{+ x} ], moreover, a better stabilization of the particles over a broader size range can be achieved so that the time window for the application of the modifying or compatibilizing layers is significantly greater. Compatibilizing in the present application here means to functionalize the particles such that a conversion into organic, hydrophobic solvents, as is the case for many applications (eg in paints) is possible. This can be done, for example, by suitable hydrophobic silanes.

The nanoparticles in preferred embodiments of the present invention are particles consisting essentially of oxides or hydroxides of silicon,

Cerium, cobalt, chromium, nickel, zinc, titanium, iron, yttrium, zirconium or mixtures thereof, wherein the particles are preferably zinc oxide or cerium oxide particles or mixed oxide particles containing at least one of these ingredients.

The particles according to the invention preferably have an average particle size determined by means of particle correlation spectroscopy (PCS) or by a transmission electron microscope of 5 to 20 nm, preferably 7 to 15 nm. In particular likewise preferred embodiments of the present invention, the distribution of particle sizes is narrow, ie the d50 value, and in particularly preferred embodiments even the d90 value is preferably in the ranges indicated above from 5 to 15 nm, or even 7 to 12 nm.

In a variant of the invention, it is preferred if the particles have a further surface modification, which is preferably a silica coating and / or a hydrophobic modification.

For the purposes of the present invention, silica means a material consisting essentially of silicon dioxide and / or silicon hydroxide, it also being possible for the Si atoms to carry organic radicals which were already present in the modifiers.

Surface modifiers for hydrophobic modification are, for example, selected from the group of organofunctional silanes, quaternary ammonium compounds, phosphonates, phosphonium and sulfonium compounds or mixtures thereof. A preferred surface modifier is an organofunctional silane, as described in more detail below.

In a further variant of the invention it is preferred if the particles according to the invention contain a silica coating and additionally further with a surface modifier selected from the group of organofunctional silanes, quaternary ammonium compounds, phosphonates, phosphonium and sulfonium compounds or mixtures thereof. A preferred surface modifier is an organofunctional silane, as further described in detail below, modified.

A further subject of the present invention is a corresponding production process, ie a process for the production of nanoparticles having an average particle size in the range from 3 to 50 nm dispersed in an organic solvent, characterized in that one or more precursors for the nanoparticles are reacted in an organic solvent with a compound M ₃ -χ [O _3-x SiRi _{+ x} ] to the nanoparticles, where x is one Whole number selected from 0, 1 or 2, M is H, Li, Na or K and each R independently represents a branched or unbranched, saturated or unsaturated hydrocarbon radical having 1 to 28 carbon atoms in which one or more C Atoms can be replaced by O.

Accordingly, for example, water-soluble metal compounds, preferably silicon, cerium, cobalt, chromium, nickel, zinc, titanium, iron, yttrium and / or zirconium compounds, can be used as precursors for the inorganic nanoparticles. Preferably precursors are zinc salts of carboxylic acids, for example zinc acetate or halides. In this case, mixed oxides can be obtained in a simple manner by suitable mixing of the corresponding precursors. The choice of suitable precursors presents no difficulty to the person skilled in the art, all compounds which are suitable for precipitating the corresponding target compounds from aqueous solution are suitable. An overview of suitable precursors for preparing oxides is given, for example, in Table 6 in K. Osseo-Asare "Microemulsion-mediated Synthesis of Nanosize Oxide Materials" in: Kumar P., Mittal KL, (editors), Handbook of microemulsion science and technology, New York: Marcel Dekker, Inc., pp. 559-573, the contents of which are expressly assigned to the disclosure of the present application.

In one embodiment, in addition, a base may be MOH, where M is Li, Na, or K, wherein the proportion of base in the total of M _3-x [θ ₃ -χSiR _{1 + x} ] and base is up to 99.5 %. If an additional base MOH is to be used, the Proportion of base preferably 10-70 mol% based on the total amount or particularly preferably 30-60 mol%.

In the compounds M _3-x [θ ₃ . _x SiRi _{+ x} ] is preferably at least one radical R is an alkoxy radical having 1 to 27 carbon atoms, preferably a methoxy or ethoxy radical.

In a further preferred embodiment, x is 2 and all R are each independently methyl or ethyl.

In preferred compounds M _3-x [θ _3-x SiRi ₊ χ], all R are each independently methyl, ethyl, methoxy or ethoxy. It may further be preferred according to the invention if M is K. It is particularly preferred in a variant of the invention if x is 2 and the formula of the named compounds is correspondingly simplified to M [OSiR ₃ ]. Very particularly preferred is the use of compounds of the formula K [OSiR ₂ CH ₃ ], with R, as indicated above, wherein all R are preferably methyl.

Further preferred combinations are disclosed in the claims.

In a further embodiment, it is preferred that the compound M _3-x [O _3-x SiR _{1 + x} ], where M is Li, Na or K and x and R are as defined above, in situ from a base MOH and a compound R ' ₃ -χ [O _3- χSiRi _{+ x} ] is produced, wherein R' is an alkyl group having 1 to 16 carbon atoms, preferably having 1 to 4 carbon atoms, most preferably ethyl.

In a further variant of the invention, it is preferred if, in a further reaction step, at least one modifier for producing a silica coating or a surface modifier is selected from the group organofunctional silanes, quaternary ammonium compounds, phosphonates, phosphonium and sulfonium compounds, is added to produce a hydrophobic shell.

The modifier which is a precursor for silica is preferably a trialkoxysilane or a tetraalkoxysilane, alkoxy preferably being methoxy or ethoxy, particularly preferably methoxy. Particularly preferred according to the invention is the use of tetramethoxysilane (TMOS) as a modifier.

The addition of the modifier is usually carried out 1 to 50 minutes after the start of the reaction, preferably 10 to 40 minutes after the start of the reaction and more preferably after about 30 minutes.

In a particularly preferred variant of the method according to the invention, at least one surface modifier is added after coating with a silica coating in a further reaction step, wherein the modifier is preferably organofunctional silanes, quaternary ammonium compounds, phosphonates, phosphonium and sulfonium compounds.

It is possible by the preferred treatment with a surface modifier, the nanoparticles almost agglomerate-free from the dispersions to isolate, since the individual particles form directly coated. In addition, the nanoparticles obtainable by this method can be particularly easily and uniformly redispersed, in particular an undesired impairment of the transparency of such dispersions in the visible

Light can be largely avoided. Suitable surface modifiers (modifiers) are, for example, organofunctional silanes, quaternary silanes

Ammonium compounds, phosphonates, phosphonium and sulfonium compounds or mixtures thereof. Preferably, the surface modifiers are selected from the group of organofunctional silanes.

In particular, according to the invention, the described requirements for a surface modifier fulfill an adhesion promoter which carries two or more functional groups. One group of the coupling agent chemically reacts with the oxide surface of the nanoparticle. Alkoxysilyl groups (for example methoxy-, ethoxysilanes), halosilanes (for example chlorine) or acidic groups of phosphoric acid or phosphonic acids and phosphonic acid esters are suitable here. Via a more or less long spacer, the groups described are linked to a second, functional group. These spacers are unreactive alkyl chains, siloxanes, polyethers, thioethers or urethanes or combinations of these groups of the general formula (C ₁ Si) _n H m (N ₁ O ₁ S) _x where n = 1-50, m = 2 -100 and x = 0-50. The functional group is preferably acrylate, methacrylate, vinyl, amino, cyano, isocyanate, epoxy, carboxy or hydroxy groups.

Silane-based surface modifiers are described, for example, in DE 40 11 044 C2. Phosphoric acid-based surface modifiers are available, inter alia, as Lubrizol® 2061 and 2063 from LUBRIZOL (Langer & Co.). Suitable silanes are, for example, alkyltrimethoxysilanes with C3 to C18, vinyltrimethoxysilane, aminopropyltriethoxysilane, N-ethylamino-N-propyldimethoxysilane, isocyanatopropyltriethoxysilane, mercaptopropyltrimethoxysilane, vinyltriethoxysilane, Vinylethyldichlorosilane, vinylmethyldiacetoxysilane,

Vinylmethyldichlorosilane, vinylmethyldiethoxysilane, vinyltriacetoxysilane,

Vinyltrichlorosilane, phenylvinyldiethoxysilane, phenylallyldichlorosilane,

3-isocyanatopropoxyltriethoxysilane, methacryloxypropenyltrimethoxysilane,

3-methacryloxypropyltrimethoxysilane, 3

Glycidyloxypropyltrimethoxysilane, 1,2-epoxy-4- (ethyltriethoxysilyl) -cyclohexane, 3-acryloxypropyltrimethoxysilane, 2-

Methacryloxyethyltrimethoxysilane, 2-acryloxyethyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, 2-

Methacryloxyethyltriethoxysilane, 2-acryloxyethyltriethoxysilane,

3-methacryloxypropyl tris (methoxyethoxy) silane _; 3

Methacryloxypropyl tris (butoxyethoxy) silane,

3-methacryloxypropyltris (propoxy) silane, 3-methacryloxypropyltris (butoxy) silane, 3

Acryloxypropyltris (methoxyethoxy) silane, 3-acryloxypropyltris (butoxyethoxy) silane, 3-acryloxypropyltris (propoxy) silane,

3-acryloxypropyltris (butoxy) silane. Particularly preferred

3-methacryloxypropyltrimethoxysilane and hexadecyltrimethoxysilane. These and other silanes are commercially available e.g. at ABCR GmbH & Co.,

Karlsruhe, or the company Sivento Chemie GmbH, Dusseldorf, available. Very particularly preferred is as

Surface modifier as described above

Hexadecyltrimethoxysilane used.

Vinylphosphonic acid or vinylphosphonic acid diethyl ester can also be listed here as adhesion promoters (manufacturer: Hoechst AG, Frankfurt am Main).

Particularly preferably it is also when the general formula (R) b If the surface modifier is an amphiphilic silane of _{3 Si-Sp-P} Ah -B _h, where the radicals R are identical or Sp can be either -O- or straight-chain or branched alkyl having 1-18 C atoms, straight-chain or branched alkenyl having 2-18 C atoms and one or more double bonds, straight-chain or branched alkynyl having 2 -18 C atoms and one or more triple bonds, saturated, partially or fully unsaturated cycloalkyl having 3-7 C atoms, which may be substituted by alkyl groups having 1-6 C atoms, Ah _{P represents} a hydrophilic block, B _hb is a hydrophobic block and wherein preferably at least one reactive functional group is present bound to Ah _P and / or B _hb is.

Particularly preferred is the use of ((3-trimethoxysilanyl-propyl) -carbamic acid-2- (2-hexy-ethoxy) -ethyl-ester).

The amphiphilic silanes contain a head group (R) ₃ Si, where the radicals R may be the same or different and represent hydrolytically removable radicals. Preferably, the radicals R are the same.

Suitable hydrolytically removable radicals are, for example, alkoxy groups having 1 to 10 C atoms, preferably having 1 to 6 C atoms, halogens, hydrogen, acyloxy groups having 2 to 10 C atoms and in particular having 2 to 6 C atoms or NRV groups, the Radicals R ^{'may be the} same or different and are selected from hydrogen or alkyl having 1 to 10 C atoms, in particular having 1 to 6 C atoms. Suitable alkoxy groups are, for example, methoxy, ethoxy, propoxy or butoxy groups. Suitable halogens are in particular Br and Cl. Examples of acyloxy groups are acetoxy or propoxy groups. Oximes are also suitable as hydrolytically removable radicals. The oximes may hereby be substituted by hydrogen or any organic radicals. The radicals R are preferably alkoxy groups and in particular methoxy or ethoxy groups. Covalently bonded to the above-mentioned head group is a spacer S _P , which acts as a link between the Si head group and the hydrophilic block A _hP and performs a bridging function in the context of the present invention. The group Sp is either -O- or straight-chain or branched alkyl having 1-18 C atoms, straight-chain or branched alkenyl having 2-18 C atoms and one or more double bonds, straight-chain or branched alkynyl having 2-18 C atoms and one or more triple bonds, saturated, partially or fully unsaturated cycloalkyl having 3-7 C atoms, which may be substituted by alkyl groups having 1-6 C atoms.

The C 1 -C ₁₈ -alkyl group of Sp is, for example, a methyl, ethyl, isopropyl, propyl, butyl, sec-butyl or tert-butyl, and also pentyl, 1, 2- or 3-methylbutyl, 1, 1-, 1, 2- or 2,2-dimethylpropyl, 1-ethylpropyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl , Tridecyl or tetradecyl group. Optionally it may be perfluorinated, for example as difluoromethyl, tetrafluoroethyl, hexafluoropropyl or octafluorobutyl.

A straight-chain or branched alkenyl having 2 to 18 C atoms, wherein several double bonds may also be present, is, for example, vinyl, allyl, 2- or 3-butenyl, isobutenyl, sec-butenyl, furthermore 4-pentenyl, isopentenyl, Hexenyl, heptenyl, octenyl, -CgHi ₆ , - C10H18 to -Ci ₈ H ₃₄ , preferably allyl, 2- or 3-butenyl, isobutenyl, sec-butenyl, furthermore preferred is 4-pentenyl, iso-pentenyl or hexenyl.

A straight-chain or branched alkynyl having 2 to 18 C atoms, wherein a plurality of triple bonds may also be present, is, for example, ethynyl, 1- or 2-propynyl, 2- or 3-butynyl, furthermore

Pentynyl, 3-pentynyl, hexynyl, heptynyl, octynyl, -C ₉ H ₁₄ , -Ci ₀ Hi ₆ bis - C- _I sH ₃₂ , preferably ethynyl, 1- or 2-propynyl, 2- or 3-butynyl, 4-pentynyl, 3-pentynyl or hexynyl.

Unsubstituted saturated or partially or fully unsaturated cycloalkyl groups having 3-7 C atoms may be cyclopropyl, cyclobutyl,

Cyclopentyl, cyclohexyl, cycloheptyl, cyclopentenyl, cyclopenta-1, 3-dienyl, cyclohexenyl, cyclohexa-1,3-dienyl, cyclohexa-1,4-dienyl,

Phenyl, cycloheptenyl, cyclohepta-1, 3-dienyl, cyclohepta-1, 4-dienyl or cyclohepta-1, 5-dienyl groups which substituted with Cr to Cβ-alkyl groups.

The spacer group Sp is followed by the hydrophilic block A _hp . This may be selected from nonionic, cationic, anionic or zwitterionic hydrophilic polymers, oligomers or groups. In the simplest embodiment, the hydrophilic block is ammonium, sulfonium, phosphonium, alkyl chains with carboxyl, sulfate and phosphate side groups, which may also be present as a corresponding salt, partially esterified anhydrides with free acid or Salt group, OH-substituted alkyl or cycloalkyl chains (eg, sugars) having at least one OH group, NH- and SH-substituted alkyl or cycloalkyl chains or mono-, di- tri- or oligo-ethylene glycol groups. The length of the corresponding alkyl chains can be 1 to 20 C atoms, preferably 1 to 6 C atoms.

The nonionic, cationic, anionic or zwitterionic hydrophilic polymers, oligomers or groups can be prepared from corresponding monomers by polymerization in accordance with methods generally known to the person skilled in the art. Suitable hydrophilic monomers contain at least one dispersing functional group which consists of the group consisting of (i) functional groups which can be converted by neutralizing agents into anions, and anionic groups, and / or (ii) functional groups which are neutralized by neutralizing agents and / or

Quaternizing agents can be converted into cations, and cationic groups, and / or

(iii) nonionic hydrophilic groups.

Preferably, the functional groups (i) are selected from the group consisting of carboxylic acid, sulfonic acid and phosphonic acid groups, acidic sulfuric acid and

Phosphoric acid ester groups and carboxylate, sulfonate, phosphonate, sulfate ester and phosphate ester groups, the functional groups (ii) from the group consisting of primary, secondary and tertiary amino groups, primary, secondary, tertiary and quaternary ammonium groups, quaternary phosphonium groups and tertiary sulfonium groups, and the functional groups (iii) are selected from the group consisting of omega-hydroxy and omega-alkoxy-poly (alkylene oxide) -1-yl groups.

Unless neutralized, the primary and secondary amino groups may also serve as isocyanate-reactive functional groups.

Examples of suitable hydrophilic monomers having functional groups (i) are acrylic acid, methacrylic acid, beta-carboxyethyl acrylate, ethacrylic acid, crotonic acid, maleic acid, fumaric acid or itaconic acid; olefinically unsaturated sulfonic or phosphonic acids or their partial esters; or maleic acid mono (meth) acryloyloxyethyl ester, succinic acid mono (meth) acryloyloxyethyl ester or phthalic acid mono (meth) acryloyloxyethyl ester, in particular acrylic acid and methacrylic acid. Examples of suitable hydrophilic monomers with functional groups (ii) are 2-aminoethyl acrylate and methacrylate or allylamine.

Examples of suitable hydrophilic monomers having functional groups (iii) are omega-hydroxy or omega-methoxy-polyethylene oxide-1-yl, omega-methoxy-polypropylene oxide-1-yl or omega-methoxy-poly-ethylene oxide-co-polypropylene oxide. i-yl acrylate or methacrylate, and hydroxy subsitituted ethylenes, acrylates or methacrylates, such as hydroxyethyl methacrylate.

Examples of suitable monomers for the formation of zwitterionic hydrophilic polymers are those in which a betaine structure occurs in the side chain. Preferably, the side group is selected from - (CH ₂ ) _m - (N ⁺ (CH 3) 2) - (CH ₂ ) _n -SO ₃ -, CH ₂ ) _m - (N ⁺ (CH ₃ ) ₂ ) - (CH ₂ ) _n -PO ₃ ² -, - (CH ₂ ) _m - (N ⁺ (CH ₃ ) 2) - (CH ₂ ) _n -O-PO 3 ² - orMeCH ₂ ) _m - (P ⁺ (CH 3) ₂ MCH ₂ ) _n -SO ₃ -, where m is an integer from the range of 1 to 30, preferably from the range 1 to 6, particularly preferably 2, and n is an integer from the range of 1 to 30, preferably from the range 1 to 8, particularly preferably 3.

It may be particularly preferred if at least one structural unit of the hydrophilic block has a phosphonium or sulfonium radical.

In selecting the hydrophilic monomers, it is to be noted that it is preferable to combine the hydrophilic monomers having functional groups (i) and the hydrophilic monomers having functional groups (ii) so as not to form insoluble salts or complexes. In contrast, the hydrophilic monomers with functional groups (i) or with functional groups (ii) be combined with the hydrophilic monomers having functional groups (iii) as desired.

Of the hydrophilic monomers described above, the monomers having the functional groups (i) are particularly preferably used.

Preferably, the neutralizing agents for the anionic functional groups (i) are selected from the group consisting of ammonia, trimethylamine, triethylamine, tributylamine, dimethylaniline, diethylaniline, triphenylamine, dimethylethanolamine, diethylethanolamine, methyldiethanolamine, 2-aminomethylpropanol, dimethylisopropylamine, dimethylisopropanolamine, triethanolamine , Diethylenetriamine and triethylenetetramine, and the neutralizing agents for the cation-convertible functional groups (ii) selected from the group consisting of sulfuric acid, hydrochloric acid, phosphoric acid, formic acid, acetic acid, lactic acid, dimethylolpropionic acid and citric acid.

Most preferably, the hydrophilic block is selected from mono-di- and triethylene glycol structural units.

Attached to the hydrophilic block A _hP is the hydrophobic block B _hb - The block B _hb is based on hydrophobic groups or, like the hydrophilic block, on the polymerization of suitable hydrophobic monomers.

Examples of suitable hydrophobic groups are straight-chain or branched alkyl having 1-18 C atoms, straight-chain or branched alkenyl having 2-18 C atoms and one or more double bonds, straight-chain or branched alkynyl having 2-18 C atoms and one or more triple bonds , saturated, partial or fully unsaturated cycloalkyl having 3-7 C atoms, which may be substituted by alkyl groups having 1-6 C atoms. Examples of such groups are already mentioned in advance. In addition, aryl, polyaryl, aryl-C ₁ -C ₆ -alkyl or esters having more than 2 C atoms are suitable. In addition, the groups mentioned may also be substituted, in particular with halogens, with perfluorinated groups being particularly suitable.

Aryl-C _r C ₆ -alkyl is, for example, benzyl, phenylethyl, phenylpropyl, phenylbutyl, phenylpentyl or phenylhexyl, it being possible for both the phenyl ring and the alkylene chain to be partially or completely substituted by F as described above, more preferably benzyl or phenylpropyl.

Examples of suitable hydrophobic olefinically unsaturated monomers for the hydrophobic block B _hp are

(1) substantially acid group-free esters of olefinically unsaturated acids, such as (meth) acrylic acid, crotonic acid, ethacrylic acid, vinylphosphonic acid or vinylsulfonic acid alkyl or cycloalkyl esters having up to 20 carbon atoms in the alkyl radical, especially methyl, ethyl, propyl, n-butyl, sec-butyl, tert-butyl, hexyl, ethylhexyl, stearyl and lauryl acrylate, methacrylate, crotonate, ethacrylate or vinyl vinonate or vinyl sulfonate; cycloaliphatic (meth) acrylic acid, crotonic acid, ethacrylic acid, vinylphosphonic acid or

Vinylsulfonic acid esters, in particular cyclohexyl, isobornyl, dicyclopentadienyl, octahydro-4,7-methano-1H-indenemethanol or tert-butylcyclohexyl (meth) acrylate, crotonate, ethacrylate, vinyiphosphonate or vinylsulfonate. These may contain, in minor amounts, higher-functional (meth) acrylic acid, crotonic acid or ethacrylic acid alkyl or cycloalkyl esters, such as ethylene glycol, Propylene glycol, diethylene glycol, dipropylene glycol, butylene glycol, pentane-1, 5-diol, hexane-1, 6-diol, octahydro-4,7-methano-1H-indenedimethanol or cyclohexane-1, 2-, -1, 3- or -1, 4-diol di (meth) acrylate, trimethylolpropane tri (meth) acrylate or pentaerythritol tetra (meth) acrylate and the analogous ethacrylates or crotonates. In the context of the present invention, minor amounts of higher-functional monomers (1) are amounts which do not lead to crosslinking or gelation of the polymers;

(2) monomers which carry at least one hydroxyl group or hydroxymethylamino group per molecule and are substantially free of acid groups, such as

Hydroxyalkyl esters of alpha.beta-olefinically unsaturated

Carboxylic acids, such as hydroxyalkyl esters of acrylic acid, methacrylic acid and ethacrylic acid, in which the hydroxyalkyl group up to 20

Containing carbon atoms, such as 2-hydroxyethyl, 2-hydroxypropyl, 3-hydroxypropyl, 3-hydroxybutyl, 4-hydroxybutyl acrylate, methacrylate or ethacrylate; 1, 4-bis (hydroxymethyl) cyclohexane, octahydro-4,7-methano-1H-indenedimethanol or methylpropanediol monoacrylate, monomethacrylate, monoethacrylate or monocrotonate; or reaction products of cyclic esters, e.g. epsilon-caprolactone and these hydroxyalkyl esters;

- olefinically unsaturated alcohols such as allyl alcohol

Allyl ethers of polyols such as trimethylolpropane monoallyl ether or pentaerythritol mono-, di- or triallyl ether. The higher functionality monomers are generally used only in minor amounts. In the context of the present invention, minor amounts of higher-functional monomers are those To understand amounts which do not lead to crosslinking or gelation of the polymers,

Reaction products of alpha, beta-olefinic carboxylic acids with

Glycidyl esters of an alpha-branched monocarboxylic acid with

5 to 18 carbon atoms in the molecule. The reaction of the acrylic or methacrylic acid with the glycidyl ester of a carboxylic acid having a tertiary alpha carbon atom may be carried out before, during or after the polymerization reaction. The monomer (2) used is preferably the reaction product of acrylic and / or methacrylic acid with the glycidyl ester of Versatic® acid. This glycidyl ester is commercially available under the name Cardura® E10. In addition, reference is made to Römpp Lexikon Lacke and Druckfarben, Georg Thieme Verlag, Stuttgart, New York, .1998, pages 605 and 606;

Formaldehyde adducts of aminoalkyl esters of alpha, beta-olefinically unsaturated carboxylic acids and of alpha, beta-unsaturated carboxylic acid amides, such as N-methylol- and N, N-dimethylolaminoethyl acrylate, -aminoethyl methacrylate, -acrylamide and -methacrylamide; such as

Acryloxysilane and hydroxyl-containing olefinically unsaturated monomers, prepared by reacting hydroxy-functional silanes with epichlorohydrin 30 and subsequent reaction of the intermediate with an alpha, beta-olefinically unsaturated carboxylic acid, in particular acrylic acid and

Methacrylic acid, or its hydroxyalkyl esters; (3) vinyl esters of alpha-branched monocarboxylic acids having 5 to 18 carbon atoms in the molecule, such as the vinyl esters of Versatic® acid sold under the trademark VeoVa®;

(4) cyclic and / or acyclic olefins such as ethylene, propylene, but-1-ene, pent-1-ene, hex-1-ene, cyclohexene, cyclopentene, norbornene, butadiene, isoprene, cyclopentadiene and / or dicyclopentadiene;

(5) amides of alpha, beta-olefinically unsaturated carboxylic acids, such as (meth) acrylamide, N-methyl-, N, N-dimethyl-, N-ethyl-,

N, N-diethyl, N-propyl, N, N-dipropyl, N-butyl, N, N-dibutyl and / or N, N-cyclohexylmethyl (meth) acrylamide;

(6) monomers containing epoxide groups, such as the glycidyl ester of acrylic acid, methacrylic acid, ethacrylic acid, crotonic acid, maleic acid,

Fumaric acid and / or itaconic acid;

(7) vinyl aromatic hydrocarbons such as styrene, vinyltoluene or alpha-alkylstyrenes, especially alpha-methylstyrene;

(8) nitriles, such as acrylonitrile or methacrylonitrile;

(9) vinyl compounds selected from the group consisting of vinyl halides such as vinyl chloride, vinyl fluoride, vinylidene dichloride, vinylidene difluoride; Vinylamides, such as N-vinylpyrrolidone; Vinyl ethers such as ethyl vinyl ether, n-propyl vinyl ether, isopropyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether and vinyl cyclohexyl ether; and vinyl esters such as vinyl acetate, vinyl propionate, and vinyl butyrate;

(10) Allyl compounds selected from the group consisting of allyl ethers and esters, such as propyl allyl ether, butyl allyl ether, ethylene glycol diallyl ether, trimethylolpropane triallyl ether or allyl acetate or allyl propionate; As far as the higher-functional monomers are concerned, what has been said above applies mutatis mutandis;

(11) Siloxane or polysiloxane monomers which may be substituted with saturated, unsaturated, straight-chain or branched alkyl groups or other hydrophobic groups already mentioned above. In addition, polysiloxane macromonomers having a number average molecular weight Mn of 1,000 to 40,000 and an average of 0.5 to 2.5 ethylenically unsaturated double bonds per molecule, such as polysiloxane macromonomers having a number average molecular weight Mn of 1,000 to 40,000 and an average of 0.5 have up to 2.5 ethylenically unsaturated double bonds per molecule; in particular polysiloxane macromonomers which have a number-average molecular weight Mn of 2,000 to 20,000, more preferably 2,500 to 10,000 and in particular 3,000 to 7,000 and an average of 0.5 to 2.5, preferably 0.5 to 1, 5, ethylenically unsaturated double bonds per molecule, as in DE 38 07 571 A 1 on pages 5 to 7, DE 37 06 095 A 1 in columns 3 to 7, EP 0 358 153 B 1 on pages 3 to 6, in US 4,754,014 A 1 in columns 5 to 9, in DE 44 21 823 A1 or in international patent application WO 92/22615 on page 12, line 18, to page 18, line 10; and

(12) carbamate or allophanate group-containing monomers such as acryloyloxy or methacryloyloxyethyl, propyl or butyl carbamate or allophanate; Further examples of suitable monomers containing carbamate groups are described in patents US 3,479,328 A 1, US 3,674,838 A 1, US 4,126,747 A 1, US 4,279,833 A 1 or US 4,340,497 A 1.

The polymerization of the abovementioned monomers can be carried out in any manner known to those skilled in the art, for example by polyaddition or cationic, anionic or radical polymerizations. Polyadditions are preferred in this context, because they can be combined with each other in a simple manner different types of monomers, such as epoxides with dicarboxylic acids or isocyanates with diols.

The respective hydrophilic and hydrophobic blocks can in principle be combined with one another in any desired manner. Preferably, the amphiphilic silanes according to the present invention have an HLB value in the range of 2-19, preferably in the range of 4-15. The HLB value is defined as _{τ ττ r} , mass polar components ..

HLB = • 20

Molar mass and indicates whether the silane behaves rather hydrophilic or hydrophobic, ie which of the two blocks Ah _P and Bhb dominates the properties of the silane according to the invention. The HLB value is calculated theoretically and results from the mass fractions of hydrophilic and hydrophobic groups. An HLB value of 0 indicates a lipophilic

Compound, a chemical compound with an HLB value of 20 _Q has only hydrophilic parts.

The amphiphilic silanes are further distinguished by the fact that at least one reactive functional group is bound to A _hp and / or B _h b. Preferably, the reactive functional group 5 is present at the hydrophobic block B _hb and there particularly preferably bound to the end of the hydrophobic block. In the preferred embodiment, the headgroup (R ^ Si and the reactive functional group are spaced as much as possible, which allows a particularly flexible design of the chain lengths of the blocks A _hp and _Q B _hb , without the possible reactivity of the reactive groups, for example with the surrounding medium to significantly reduce. The reactive functional group can be selected from silyl groups with hydrolytically removable radicals, OH, carboxy, NH, SH groups, halogens or double bonds containing reactive groups, such as acrylate or vinyl groups. Suitable silyl groups with hydrolytically removable radicals have already been described in advance in the description of the head group (R) ₃ Si. Preferably, the reactive group is an OH group.

The process according to the invention can be carried out as described above. The reaction in the process according to the invention is carried out in an organic solvent or solvent mixture. Preferred solvents are alcohols or ethers, with the use of methanol, ethanol, diethyl ether, tetrahydrofuran and / or dioxane or mixtures thereof being particularly preferred. In this case, methanol has proved to be a particularly suitable solvent.

The reaction temperature can be selected in the range between room temperature and the boiling point of the chosen solvent.

The reaction rate can be determined by appropriate selection of

Reaction temperature, the starting materials and their concentration and the

Solvent can be controlled so that the skilled person no

Difficulties to control the speed so. A control of the course of the reaction, if this is to control the

Particle size is desired, using UV spectroscopy is possible.

In certain cases, it may be helpful to use an emulsifier, preferably a nonionic surfactant. Preferred emulsifiers are optionally ethoxylated or propoxylated, longer-chain alkanols or alkylphenols having different Ethoxylation or propoxylation degrees (eg adducts with 0 to 50 moles of alkylene oxide).

Also, dispersants can be used advantageously, preferably water-soluble high molecular weight organic compounds with polar groups, such as polyvinylpyrrolidone, copolymers of

Vinyl propionate or acetate and vinylpyrrolidone, partially hydrolyzed

Copolymeriste of an acrylic ester and acrylonitrile, polyvinyl alcohols having different residual acetate content, cellulose ethers, gelatin, block copolymers, modified starch, low molecular weight, carbon- and / or sulfonic acid-containing polymers or mixtures of these substances can be used.

Particularly preferred protective colloids are polyvinyl alcohols having a residual acetate content of less than 40, in particular 5 to 39 mol .-% and / or vinylpyrrolidone / vinyl propionate copolymers having a vinyl ester content of less than 35, in particular 5 to 30 wt .-%.

By adjusting the reaction conditions, such as temperature, pressure, reaction time can be specifically set the desired property combinations of the required nanoparticles. The corresponding setting of these parameters does not cause any difficulties for the skilled person. For example, you can work for many purposes at atmospheric pressure and room temperature.

The nanoparticles according to the invention are used in particular for UV protection in polymers. The particles protect either the polymers themselves against degradation by UV radiation, or the polymer preparation containing the nanoparticles is - again used as a UV protection for other materials - for example in the form of a protective film or applied as a lacquer layer. The corresponding use of nanoparticles according to the invention for the UV Stabilization of polymers and UV stabilized

Polymer formulations consisting essentially of at least one polymer or a paint formulation, which are characterized in that the polymer nanoparticles according to the invention contains, are therefore further objects of the present invention.

For the purposes of using these nanoparticles for UV protection in polymers, it is particularly preferred if the absorption edge of a dispersion with, for example, 0.001% by weight of the nanoparticles in the range 300-500 nm, preferably in the range up to 300-400 nm and particularly preferably in Range is 320 to 380 nm. According to the invention it is particularly preferred if the transmission of this suspension (or synonymously also used dispersion) with a layer thickness of 10 mm, containing 0.001 wt .-%, wherein the wt .-% - indication is determined by the investigation method, at 320 nm less than 10%, preferably less than 5% and at 440 nm greater than 90%, preferably greater than 95%.

For incorporation into polymers, it is essential to use isolated nanoparticles.

The invention therefore also nanoparticles with an average particle size determined by means

Particle Correlation Spectroscopy (PCS) in the range of 3 to 50 nm, characterized in that they are obtainable by the method according to the invention as described above or specified in the claims, but the organic solvent is removed for drying.

Another object of the invention is therefore also a method for producing such isolated nanoparticles, wherein the organic solvent is removed in a last step until drying.

Polymers in which the nanoparticles according to the invention can be well incorporated are in particular polycarbonate (PC), polyethylene terephthalate (PETP), polyamide (PI), polystyrene (PS), polymethyl methacrylate (PMMA) or copolymers which contain at least a portion of one of the polymers mentioned ,

The incorporation can be carried out by conventional methods for the preparation of polymer preparations. For example, the polymer material can be mixed with isolated nanoparticles according to the invention, preferably in an extruder or kneader.

A particular advantage of the particles according to the invention with silane coating consists in the fact that only a small energy input is required for the homogeneous distribution of the particles in the polymer in comparison with the prior art.

The polymers may also be dispersions of polymers, such as, for example, paints or lacquer preparations. Here, the incorporation can be done by conventional mixing processes. The good redispersibility of the particles according to the invention makes it easier to prepare such dispersions. Accordingly, dispersions of the particles according to the invention in polymers or solvents as dispersing medium are a further subject of the present invention.

The paints may be, for example, alkyd resin, chlorinated rubber, epoxy resin, acrylate resin, oil, nitro, polyester or

Polyurethane lacquers or combination lacquers on cellulose nitrate u. Alkyd resin base act. Of great importance here are the polyurethane paints.

The solvents used in dispersions of the invention are preferably ether alcohols, aliphatics, alcohols, aromatics, chlorinated hydrocarbons, esters, hydroaromatics, ketones,

Terpene hydrocarbons and / or water used.

Also suitable are the polymer preparations according to the invention containing the nanoparticles or also the inventive compositions

Dispersions as described above or defined in claims 7 and / or 8, in particular also for the coating of surfaces, for example of wood, plastics, fibers or glass. Thus, the surface or the underlying material under the coating, for example, protect against UV radiation.

The following examples further illustrate the present invention without limiting the scope of protection. In particular, the characteristics, properties and advantages of the compounds of the examples in question are also applicable to other substances and compounds not mentioned in detail but covered by the scope of protection, unless otherwise stated elsewhere. Incidentally, the invention is embodied in the entire claimed area and is not limited to the examples mentioned here. Examples of particle correlation spectroscopy

The measurements are carried out with a Zetasizer Nano ZS from Malvern at room temperature. The measurement is carried out at a laser wavelength of 532 nm.

The sample volume is in all cases 1 ml at a concentration of 0.5% by weight of particles in butyl acetate. Before the measurement, the solutions are filtered with a 0.45 μm filter.

transmission electron Microscopy

A Tecnai 2OF from Fei Company with field emission cathode is used. The recordings are made at 200 kV acceleration voltage. Data acquisition on a 2k CCD

Gatan camera.

Preparation of liquid samples with nanoparticles for measurement in a transmission electron microscope

For sample preparation, the solution containing the nanoparticles is diluted to 1 wt .-% and dropped a drop of this solution on a kohlebefilmtes Cu mesh and then immediately "sucked dry" with a filter paper, (blotting off excess solution). The measurement of the sample takes place after drying at room temperature for one day.

Preparation of paint samples with nanoparticles for measurement in the

transmission electron microscope

The particle dispersion is mixed with the paint, so that the ZnO content after drying the paint layer is 5%. The paint is cured in a thick layer in a teflon pan, so that at least 2mm thick, free-standing films are formed. These samples are ultramicrotomed without embedding; at room temperature with 35 ° Diamond knife, section thickness 60 nm. The sections are suspended in water and transferred to coal-coated Cu nets and measured.

Example 1a: Formation of ZnO particles

A solution of 0,178mol Zn (OAc) ₂ * 2H ₂ O in 125 ml of methanol is heated to 50 ⁰ C. For this purpose, a tempered also at 50 ⁰ C solution of 0.288 mol K is [OSi (CH _{3) 3]} was added in 125 mL methanol with stirring.

The conversion to zinc oxide and the growth of the nanoparticles can be monitored by UV spectroscopy. After only one minute reaction time, the absorption maximum remains constant, ie. ZnO formation is completed in the first minute.

A stable, transparent suspension is obtained which, according to UV spectroscopy and X-ray diffraction, contains ZnO. The particle diameter after particle correlation spectroscopic examination with a Zetasizer Nano ZS from Malvern (PCS) is 4 -12 nm with a d50 of 6-7 nm and a d90 of 5-10 nm. The size is thus in the range of less than 15 -20nm, as needed for transparent applications. The particles thus produced are stable for several hours, so that they can be further functionalized.

A comparative experiment with KOH instead of K [OSi (CH ₃ ) ₃ ] as the base (Example 3) shows continued particle growth, evidenced by the solution becoming cloudy after a few minutes and finally a precipitate of precipitated zinc oxide particles. This sediment is easily filtered off, the size of the particles or their Agglomerates are thus well above the target size of less than 15-20nm.

Example 1b: Modification by subsequent silanization

After stirring at 50 ^° C. for 30 minutes, 8.0 mmol of hexadecyltrimethoxysilane are added to the dispersion of Example 1a. The mixture is stirred for 5 h at 50 ⁰ C. The separation of the hydrophobic particles is carried out by shaking with pentane or petroleum ether.

A stable, transparent suspension is obtained which, according to UV spectroscopy and X-ray diffraction, contains ZnO. Furthermore, no reflections of potassium acetate are visible in the X-ray diagram. Of the

Diameter of the particles is after

Photon correlation spectroscopic investigation with a

Zetasizer Nano ZS from Malvern (PCS) 4 -12 nm with a d50 of 6 - 7 nm and a d90 of 5 - 10 nm.

A new measurement after 10 days gives the same values as part of the measurement accuracy. Agglomeration of the particles can thus be excluded.

Example 1c: In Situ Generation of K [OSiMe ₃ ]

2 mol of zinc acetate dihydrate are placed in 1650 ml of methanol and the suspension is heated to 50 ⁰ C. Separately, 3.3 mol

Potassium hydroxide completely dissolved in 650 ml of methanol and then 3.3 mol of trimethylethoxysilane are added with stirring and stirred for 1 hour. This solution is added to the Zinkacetatsuspension with stirring and from this point is the

Reaction time measured. The course of the reaction is monitored by means of UV / VIS

Spectrometer tracked. When the desired absorption edge is reached, 0.08 mol of hexadecyltrimethoxysilane are added and 5 hours stirred at 50 ⁰ C. Thereafter, 1500 ml of petroleum benzine are added to the reaction mixture.

A stable, transparent suspension is obtained which, according to UV spectroscopy and X-ray diffraction, contains ZnO. Furthermore, no reflections of potassium acetate are visible in the X-ray diagram. The diameter of the particles is after

Photon correlation spectroscopic examination with a Zetasizer Nano ZS from Malvern (PCS) 4 -12 nm with a d50 of 6-7 nm and a d90 of 5-10 nm. A new measurement after 10 days gives the same values within the scope of the measurement accuracy. Agglomeration of the particles can thus be excluded.

Example 2a: Modification by TMOS addition

After 30 min, 8.0 mmol of tetramethyl orthosilicate (TMOS) is added to the dispersion according to Example 1 and further stirred at 5O ⁰ C.

A stable, transparent suspension is obtained which, according to UV spectroscopy and X-ray diffraction, contains ZnO. According to particle correlation spectroscopic examination with a Zetasizer Nano ZS from Malvern (PCS), the diameter of the particles is 4 -12 nm with a d50 of 6 to 7 nm and a d90 of 5 to 10 nm.

Example 2b: Modification by TMOS addition and subsequent silanization

After 60 min, 10.0 mmol hexadecyltrimethoxysilane be given to that described in Example 2a suspension under stirring at 50 ⁰ C. The mixture is stirred for 5 h at 50 ⁰ C. The separation of hydrophobic particles are made by shaking with pentane or petroleum ether.

A stable, transparent suspension is obtained which, according to UV spectroscopy and X-ray diffraction, contains ZnO. Furthermore, no reflections of potassium acetate are visible in the X-ray diagram. The diameter of the particles is after

Photon correlation spectroscopic examination with a Zetasizer Nano ZS from Malvern (PCS) 4 -12 nm with a d50 of 6-7 nm and a d90 of 5-10 nm. A new measurement after 10 days gives the same values within the scope of the measurement accuracy. Agglomeration of the particles can thus be excluded.

Comparative Example 3: ZnO preparation with KOH A solution of 0.4 mol Zn (OAc) ₂ * 2H2θ in 250 mL of methanol is heated to 50 ⁰ C. For this purpose, a likewise heated to 50 ⁰ C solution of 0.680 mol KOH in 250 mL of methanol is added with stirring.

The conversion to zinc oxide and the growth of the nanoparticles can be monitored by UV spectroscopy. After only 10 minutes, a white precipitate of zinc oxide precipitates. The reaction is continued for 5 hours. The precipitate is washed with methanol.

A white suspension is obtained which contains ZnO according to X-ray diffraction. Furthermore, no X-ray reflections of potassium acetate are visible.

Example 4: Measurement of photocatalytic activity

As a model substance to be degraded, isopropanol is used on photoactive surfaces via the intermediate acetone in the presence of Water vapor and oxygen is oxidized under irradiation to CO ₂ . The speed of this reaction is considered as a measure of the photoactivity of the substance being examined. From each of the substances, ie ZnO from Example 1 b, 2b and 3, in each case 1, 58 g by means of a stand sieve (diameter 5 cm, 127 mesh) with the aid of a fine brush directly into a Petri dish. The intensity of the UV-A radiation acting on this substance is set to 15 mW / cm ² immediately before the examination. After the sample to be examined for photocatalytic activity is placed in the reactor, after thorough rinsing of the apparatus with the carrier gas (synthetic air), a defined water gas concentration is set via the humidifier during flow operation (dosing rate 1800 μl / h to 10000 ppm). After switching to the circulatory operating mode, exactly 1 μl of isopropanol is now injected via the septum into the gas chamber, which is continuously circulated by the pump. After the adsorption / desorption equilibrium between sample surface and gas phase has been established, the irradiation is switched on. The potential degradation of the components to be oxidized and their secondary products can be quantitatively monitored from the FTIR continuously recorded spectra. The software of the computer connected to the FTIR evaluates the respective experimental spectrum as the sum of the reference spectra of species involved in the degradation process. From the proportions of their intensity on the experimental spectrum, the concentration of each individual component in the gas phase can be calculated. The difference in the concentrations before and after the irradiation is a measure of the photocatalytic degradation. Table: Difference value from the measured

Gas phase concentrations of acetone before and after 45 minutes of irradiation of the samples at 15 mW / cm ²

The ZnO from example 2b (sample 3) shows the lowest photocatalytic activity.

Example 5:

Preparation of a polymer nanocomposite:

The suspension of example 2b is applied under reduced pressure until

Dry concentrated. A fine, free-flowing powder of surface-modified zinc oxide is obtained.

10 g of these particles are in the extruder with 1 kg of PMMA

(Polymethylmethacrylat, PMMA molding compound 7H Degussa Röhm) mixed and 10 g of the resulting granules with 100 g of the same

Polymers re-extruded. The nanocomposite obtained is by means of

Injection molding processed to 1, 5 mm thick plates. These are transparent and exhibit <5% at 350 nm,> 90% transmission at 450 nm, measured on the UV-vis spectrometer.

Example 6: incorporation into paint

Preparation of a paint preparation containing ZnO nanoparticles

There are two components by mixing the following

Ingredients made:

Component A 46.39 g Desmophen A 870 BA, 70% in butyl acetate (Bayer) 0.5 g Baysilone © lacquer additive OL 17, 10% strength in Xyloo (from Borchers GmbH)

14.67 g of a 1: 1 mixture of 1-methoxypropyl acetate-2 and Solventnaphta 100 (from DHC Solvent-Chemie GmbH) 12.5 g of ZnO dispersion from Example 2b

Component B

9.98 g Desmodur N 3390 BA / SN, 90% strength in butyl acetate / solvent naphtha 100 (1: 1) (Bayer)

12.83 g Desmodur Z 4470 BA, 70% strength in butyl acetate (Bayer)

The components A and B are mixed and applied by means of a doctor blade to a glass plate with a layer thickness of 200 .mu.m.

After a flash off time of 10 minutes at RT, the paint is at 130C for

Cured for 30min. This gives an optically transparent, colorless lacquer layer of about 100μm thickness.

In the UV spectrum, this layer shows a transmission of over 95% at 400nm and less than 5% at 350nm.

Claims

claims

1. Nanoparticles having an average particle size determined by particle correlation spectroscopy (PCS) in the range of 3 to 50 nm dispersed in an organic solvent, characterized in that they are obtainable by a method in which one or more precursors for the nanoparticles in an organic solvent with a compound M _3-x [O _3- χSiRi ₊ χ] to the nanoparticles, where x is an integer selected from 0, 1 or 2, M is H, Li, Na or K and all R are each independently of one another represent a branched or unbranched, saturated or unsaturated hydrocarbon radical having 1 to 28 C atoms in which one or more C atoms may be replaced by O.

2. Nanoparticles according to claim 1, characterized in that the nanoparticles are particles consisting essentially of oxides or hydroxides of silicon, cerium, cobalt, chromium, nickel, zinc, titanium, iron , Yttrium, zirconium or mixtures thereof.

3. Nanoparticles according to claim 1 or 2, wherein the particles are preferably zinc oxide or cerium oxide particles or mixed oxide particles containing at least one of these constituents.

4. nanoparticles according to one or more of claims 1 to 3, characterized in that the particles have an average particle size determined by means of particle correlation spectroscopy (PCS) of 5 to 20 nm.

5. nanoparticles according to one or more of claims 1 to 4, characterized in that the particles have a further surface modification, which is preferably a silica coating and / or a hydrophobic modification

5 acts.

6. nanoparticles according to one or more of claims 1 to 5, characterized in that the particles containing a silica coating in addition to at least one other

I _Q surface modifiers selected from the group of organofunctional silanes, quaternary ammonium compounds, phosphonates, phosphonium and sulfonium compounds or mixtures thereof, preferably an organofunctional silane, are modified.

15

7. Nanoparticle according to one or more of claims 1 to 6, characterized in that the nanoparticle is modified with at least one organofunctional silane.

8. Dispersion comprising nanoparticles according to one or more of claims 1 to 7 and a polymer.

9. Dispersion according to claim 8, characterized in that the dispersion is a lacquer or a lacquer preparation.

²⁵

10. A process for the preparation of nanoparticles having an average particle size in the range of 3 to 50 nm dispersed in an organic solvent, characterized in that one or more precursors for the nanoparticles in an organic solvent with a compound M _3-x [O _3- χSiRi _{+ x} ] to the

³⁰ nanoparticles are reacted, where x is an integer selected from 0, 1 or 2, M is H, Li, Na or K and all R in each case independently of one another represent a branched or unbranched, saturated or unsaturated hydrocarbon radical having 1 to 28 C atoms in which one or more C atoms may be replaced by O.

11. The method according to claim 10, characterized in that the one or more precursors are selected from water-soluble metal compounds, preferably silicon, cerium, cobalt, chromium, nickel, zinc, titanium, iron, yttrium or zirconium compounds, preferably from the zinc salts of the carboxylic acids or halides.

12. The method according to claim 10 or 11, characterized in that the compound M _3-x [O _3- χSiRi ₊ χ], wherein M is Li, Na or K and x and R have the meaning given in claim 10, in is generated from a base MOH and a compound R ' ₃ - _x [O ₃ - _x SiRi _{+ x} ], where R' is an alkyl group having 1 to 16 carbon atoms.

13. The method according to one or more of claims 10 to 12, characterized in that in the compound M _3-x [θ _3-x SiRi ₊ χ], at least one R is an alkoxy radical having 1 to 27 carbon atoms, preferably a methoxy or ethoxy radical.

14. The method according to one or more of claims 10 to 13, characterized in that in the compound M _3-x [O _3-x SiRi _{+ x} ], x is 2 and each R independently of one another are methyl or ethyl.

15. The method according to one or more of claims 10 to 14, characterized in that all R is methyl and M is K.

16. The method according to one or more of claims 10 to 15, characterized in that in a further reaction step at least one modifier for producing a silica coating or a surface modifier for producing a hydrophobic shell is added.

17. The method according to one or more of claims 10 to 16, characterized in that it is the modifier for producing the silica coating is a trialkoxysilane or a tetraalkoxysilane.

18. The method according to one or more of claims 10 to 17, characterized in that after the coating with a silica coating in a further reaction step, at least one surface modifier is added, wherein it is the modifier preferably to organofunctional silanes, quaternary ammonium compounds, Phosphonates, phosphonium and sulfonium compounds.

19. The method according to one or more of claims 10 to 18, characterized in that the surface modifier is an organofunctional silane. 0

20. The method according to one or more of claims 10 to 19, characterized in that the surface modifier is an amphiphilic silane according to the general formula (R) ₃ Si-S _P -A _hp -Bhb, wherein the radicals R may be the same or different and are hydrolytically cleavable radicals, Sp is either -O- or straight-chain or branched alkyl having 1-18 C atoms, straight-chain or branched alkenyl having 2-18 C atoms and one or more double bonds, straight-chain or branched alkynyl having 2-18 C atoms and one or more triple bonds, saturated, partially or completely unsaturated cycloalkyl having 3-7 C atoms, 0 which may be substituted by alkyl groups having 1-6 C atoms, Ah _{P represents} a hydrophilic block, B _h b means a hydrophobic block and preferably at least a reactive functional group is bound to A _hP and / or B _hb .

21. The method according to one or more of claims 10 to 20, characterized in that the organic solvent is selected from alcohols or ethers.

22. The method according to one or more of claims 10 to 21, characterized in that an emulsifier, preferably a nonionic surfactant is used.

23. Nanoparticles having a mean particle size determined by means of particle correlation spectroscopy (PCS) in the range of 3 to 50 nm, characterized in that they are obtainable by a method according to one or more of claims 10 to 22, but wherein the organic solvent is removed to dryness becomes.

24. A process for the preparation of nanoparticles according to claim 23, characterized in that they are prepared by a process according to one or more of claims 10 to 22, wherein the organic solvent is removed in a final step until drying.

25. Use of nanoparticles according to at least one of claims 1 to 7 or 23 or a dispersion according to at least one of claims 8 or 9 for the UV stabilization of polymers.

26. Polymer preparation consisting essentially of at least one polymer, characterized in that the polymer contains nanoparticles according to claim 23.

27. Polymer preparation according to claim 26, characterized in that the polymers are polycarbonate (PC), polyethylene terephthalate (PETP), polyimide (PI), polystyrene (PS), polymethyl methacrylate (PMMA) or copolymers containing at least a portion of a contain the said polymers is.

28. A process for the preparation of polymer preparations according to claim 26 or 27, characterized in that the polymer material is mixed with nanoparticles according to claim 23, preferably in an extruder or a kneader.

29. Wood treated with a dispersion according to claim 8 or 9.

30. Plastic treated with a dispersion according to claim 8 or 9 or comprising a polymer preparation according to claim 26 or 27.

31. Fiber treated with a dispersion according to claim 8 or 9 or comprising a polymer preparation according to claim 26 or 27.

32. Glass treated with a dispersion according to claim 8 or 9.