EP1891167A1

EP1891167A1 - Surface-modified metal oxides, method for production and use thereof in cosmetic preparations

Info

Publication number: EP1891167A1
Application number: EP06763379A
Authority: EP
Inventors: Jens Rieger; Jutta Kissel; Valerie Andre; Nathalie Bouillo
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 2005-06-03
Filing date: 2006-05-30
Publication date: 2008-02-27
Also published as: US7666506B2; US20080193759A1; CN101189307A; DE102005025972A1; AU2006254151A1; TW200718742A; WO2006128874A1; JP2008545608A; BRPI0611064A2; KR20080017427A

Abstract

The present invention relates to surface-modified nanoparticulate metal oxides, the metal being selected from the group consisting of aluminium, cerium, iron, titanium, zinc and zirconium, characterized in that the surface modification comprises a coating with a copolymer P containing as monomers A) 1 to 99 mol% of an N-vinylamide N-vinylpyrrolidone and B) 99 to 1 mol% of a monomer containing per molecule one a,ß-ethylenically unsaturated double bond which can be polymerized by free-radical means and an anionogenic and/or anionic group with the proviso that the copolymer P must not contain further monomers selected from the group consisting of C8-Cao alkyl esters of monoethylenically unsaturated C3-C8 carboxylic acids, N-alkyl- or N,N-dialkyl-substituted amides of acrylic acid or methacrylic acid with C8-C18 alkyl radicals, or vinyl esters of aliphatic C8-C30 carboxylic acids.

Description

Surface-modified metal oxides, process for their preparation and their use in cosmetic preparations

description

The present invention relates to surface-modified nanoparticulate metal oxides, processes for their preparation and their use as UV filters in cosmetic preparations

Metal oxides are used for a variety of purposes, such as white pigment, catalyst, antibacterial skin protection cream and rubber vulcanization activator. In cosmetic sunscreens there are finely divided zinc oxide or titanium dioxide as UV-absorbing pigments

In the context of the present application, the term "nanoparticles" refers to particles having an average diameter of 5 to 10,000 nm, determined by means of electron microscopic methods

Zmkoxidnanoparticles with particle sizes below about 30 nm are potentially suitable for use as UV absorbers in transparent organic-inorganic Hybπdmaterialien, plastics, paints and coatings In addition, a use for the protection of UV-sensitive organic pigments is possible.

Particles, particle aggregates or agglomerates of zinc oxide which are greater than about 30 nm, lead to scattered light effects and thus to an undesirable decrease in transparency in the visible light. Therefore, the redispersibility, ie the convertibility of the produced Zmkoxidnanoteilchen in a colloidally disperse state , an important requirement for the above applications

Zmkoxidnanoparticles with particle sizes below about 5 nm show due to the Großquantisierungseffektes a blue shift of the absorption edge (L Brus, J Phys Chem (1986), 90, 2555-2560) and are therefore suitable for use as a UV absorber in the UV-A Bereιch less suitable.

The production of metal oxides, for example of zinc oxide by dry and wet processes, is known. The classic method of burning zinc, which is known as a dry process (eg Gmelin Volume 32, 8th ed., Supplementary Volume, p. 772 ff) Although it is basically possible to produce particle sizes in the submicrometer range by means of milling processes, dispersions with average particle sizes in the lower nanometer range are not achievable from such powders because of very low particle size. Processes produced. The precipitation in aqueous solution usually yields hydroxide and / or carbonate-containing materials which have to be thermally converted to zinc oxide. The thermal aftertreatment has a negative effect on fineness, since the particles are subjected to sintering processes which lead to the formation of micromaster-sized aggregates which can only be broken down incompletely onto the primary particles by grinding.

Nanoparticulate metal oxides can be obtained, for example, by the microemulsion method. In this method, a solution of a metal alkoxide is added dropwise to a water-in-oil microemulsion. In the inverse micelles of the microemulsion, whose size is in the nanometer range, the hydrolysis of the alkoxides to the nanoparticulate metal oxide takes place. The disadvantages of this method are, in particular, that the metal alkoxides are expensive starting materials, that in addition emulsifiers must be used and that the preparation of the emulsions with droplet sizes in the nanometer range represents a complex process step.

DE 199 07 704 describes a nanoparticulate zinc oxide prepared by a precipitation reaction. Here, the nanoparticulate zinc oxide is prepared from a Zinkacetatiösung via an alkaline precipitate. The centrifuged zinc oxide can be redispersed by addition of methylene chloride to a sol. The zinc oxide dispersions prepared in this way have the disadvantage that they have no good long-term stability owing to the lack of surface modification.

WO 00/50503 describes zinc oxide gels which contain nanoparticulate zinc oxide particles having a particle diameter of ≦ 15 nm and which are redispersible to give brines. The precipitations produced by basic hydrolysis of a zinc compound in alcohol or in an alcohol / water mixture are added by addition of dichloromethane or chloroform redispersed. The disadvantage here is that no stable dispersions are obtained in water or in aqueous dispersants.

In the publication from Chem. Mater. 2000, 12, 2268-74 "Synthesis and Characterization of Poly (vinylpyrrolidone) Modified Zinc Oxide Nanoparticles" by Lin Guo and Shihe Yang, Wurtzit zinc oxide nanoparticles are surface-coated with polyvinylpyrrolidone. The disadvantage here is that coated with polyvinylpyrrolidone zinc oxide particles are not dispersible in water.

WO 93/21 127 describes a process for producing surface-modified nanoparticulate ceramic powders. In this case, a nanoparticulate ceramic powder is surface-modified by applying a low-molecular organic compound, for example propionic acid. This method can not be used for the surface modification of zinc oxide since the modification reaction tions are carried out in aqueous solution and Ziπkoxid dissolves in aqueous organic acids. Therefore, this method can not be used for the production of zinc oxide dispersions; Moreover, zinc oxide in this application is also not mentioned as a possible starting material for nanoparticulate ceramic powders.

JP-A-04 164 814 describes a process which leads to finely divided ZnO by precipitation in an aqueous medium at elevated temperature even without thermal aftertreatment. The mean particle size is 20 to 50 nm, without specifying the degree of agglomeration. These particles are relatively large. This leads to scattering effects even with minimal agglomeration, which are undesirable in transparent applications.

JP-A-07 232 919 describes the preparation of ZnO particles of zinc particles of from 5 to 10000 nm by reaction with organic acids and other organic compounds such as alcohols at elevated temperature. The hydrolysis takes place here in such a way that the by-products formed (esters of the acids used) can be distilled off. The method allows the production of ZnO-Puivern, which are redispersible by previously carried out surface modification. However, based on the disclosure of this application, it is not possible to produce particles with an average diameter <15 nm. Accordingly, in the examples given in the application, the smallest average primary particle diameter is 15 nm.

Metal oxides hydrophobized with organosilicon compounds are described i.a. described in DE 33 14 741 A1, DE 36 42 794 A1 and EP 0 603 627 A1 and in WO 97/16156.

These metal oxides coated with silicone compounds, for example zinc oxide or titanium dioxide, have the disadvantage that oil-in-water or water-in-oil emulsions produced therewith do not always have the necessary pH stability.

Furthermore, incompatibilities of various metal oxides coated with silicone compounds are frequently observed with one another, which can lead to undesirable aggregate formation and flocculation of the various particles.

It is an object of the present invention to provide nanoparticulate metal oxides which permit the preparation of stable nanoparticulate dispersions in water or polar organic solvents as well as in cosmetic oils. An irreversible aggregation of the particles should be avoided if possible, so that a complex milling process can be avoided.

This object has been achieved by surface-modified nanoparticulate metal oxides, where the metal is selected from the group consisting of aluminum, cerium, Iron, titanium, zinc and zirconium, characterized in that the surface modification comprises a charge of a copolymer P containing as monomers

A) 1 to 99 mol%, preferably 50 to 99 mol%, particularly preferably 75 to 99 mol% of an N-vinylamide and

B) 99 to 1 mol%, preferably 50 to 1 mol%, particularly preferably 25 to 1 mol% of a monomer containing per molecule a radically polymerizable α, ß ethylenically unsaturated double bond and an anionogenic and / or anionic see Group,

with the proviso that the copolymer P no further monomers selected from the group consisting of Cs-C3o-alkyl esters of monoethylenically unsaturated C3-C8 carboxylic acids, N-alkyl or N, N-dialkyl-substituted amides of acrylic acid or Methacrylic acid with C ₃ -Cis-alkyl radicals, or may contain vinyl esters of aliphatic C8-C30 carboxylic acids.

The monomer A) is selected from the substance group of N-vinylamides. These may be both open-chain and cyclic N-vinylamides (N-vinyllactams). The monomers chosen usually have 2 to 15 carbon atoms, preferably 2 to 10 carbon atoms. Examples of N-vinylamides or N-vinyllactams are those which are characterized by the following formula (I):

^{R4 ^ N} γ ^{0 0)}

R5

in the

R 4, R 5 independently of one another are H or C 1 -C 6 -alkyl or may together form an A-to 8-membered cycle which may be saturated or mono- or polyunsaturated and may optionally carry further substituents.

Suitable open-chain compounds of this type are, for example, N-vinylformamide, N-vinyl-N-methylformamide, N-vinyl-N-ethylformamide, N-vinyl-N-propylformamide, N-vinyl-N-isopropylformamide, N-vinylene [-N butylformamide, N-vinyl-N-isobutylformamide, N-vinyl-Nt-butylformamide, N-vinyl-Nn-pentylformamide, N-vinyl-Nn-hexylformamide, N-vinylacetamide, N-vinyl-N-methylacetamide, NΛ / inyl- N-ethylacetamide, N-vinylpropionamide, N-vinyl-N-methylpropionamide and N-vinylbutyramide. Particularly preferred are N-vinylformamide and N-vinyl-N-methylacetamide, Of the cyclic N-vinylamides, the N-vinyllactams, examples which may be mentioned are N-vinylpyrrolidone, N-vinylpiperidone and N-vinylcaprolactam. According to the invention, N-vinylpyrrolidone is preferably used, while N-vinylformamide of the open-chain N-vinylamides is preferably used. Copolymers of, for example, N-vinylformamide and N-vinylpyrrolidone, which may be present in the copolymer in any desired ratio, can be used in accordance with the invention.

The monomers A) can be used as such or as mixtures with one another.

The monomer B) contains per molecule a radically polymerizable α, β-ethylenically unsaturated double bond and one anionogenic and / or anionic group per molecule.

Preferably, the compounds B) are selected from monoethylenically unsaturated carboxylic acids, sulfonic acids, phosphonic acids and mixtures thereof.

As monoethylenically unsaturated carboxylic acids are monoethylenically unsaturated mono- and dicarboxylic acids having 3 to 25, preferably 3 to 8 carbon atoms to understand. Examples thereof are acrylic acid, methacrylic acid, dimethacrylic acid, ethacrylic acid, α-chloroacrylic acid, maleic acid, methylenemalonic acid, allylacetic acid, vinylacetic acid, crotonic acid, citraconic acid, mesaconic acid, glutaconic acid, aconitic acid, fumaric acid, and itaconic acid. Acrylic acid, methacrylic acid, maleic acid or mixtures of said carboxylic acids are preferably used from this group of monomers. The monoethylenically unsaturated carboxylic acids can be used in the form of the free acid and, if present, the anhydrides or in partially or completely neutralized form in the copolymerization. To neutralize these monomers it is preferred to use alkali metal or alkaline earth metal bases, ammonia or amines, e.g. Sodium hydroxide solution, potassium hydroxide solution, soda, potash, Nathumhydro- gencarbonat, magnesium oxide, calcium hydroxide, calcium oxide, gaseous or aqueous ammonia, triethylamine, ethanolamine, diethanolamine, triethanolamine, morpholine, diethylenetriamine or tetraethylenepentamine.

The monomers B) furthermore include the half-esters of monoethylenically unsaturated dicarboxylic acids having 4 to 10, preferably 4 to 6, carbon atoms, eg. B. of maleic acid such as monomethyl maleate.

The monomers B) also include monoethylenically unsaturated suifonic acids and phosphonic acids, for example vinylsulfonic acid, allylsulfonic acid, methallylsulfonic acid, sulfoethyl acrylate, sulfoethyl methacrylate, sulfopropyl acrylate, sulfopropyl methacrylate, 2-hydroxy-3-acryloxypropylsulfonic acid, 2-hydroxy-3-methacryloxypropylsulfonic acid, styrenesulfonic acid, 2-acrylamido-2- methylpropanesulfonic acid, vinylphosphonic acid, allylphosphonic acid and acrylamido methanepropanephosphonic acid.

The monomers B) can be used as such or as mixtures with one another.

Preferably, component B) is selected from acrylic acid, methacrylic acid, ethacrylic acid, α-chloroacrylic acid, crotonic acid, maleic acid, maleic anhydride, fumaric acid, itaconic acid, citraconic acid, mesaconic acid, glutaconic acid, aconitic acid and mixtures thereof.

Component B) is particularly preferably selected from acrylic acid, methacrylic acid, maleic anhydride and mixtures thereof, very particularly preferably acrylic acid.

Copolymer P to be used particularly advantageously as a coating for the surface-modified nanoparticulate metal oxides according to the invention contains from 75 to 99 mol% of N-vinylpyrrolidone and from 1 to 25 mol% of acrylic acid.

Excluded as additional comonomers for the polymer P are:

a)

Cβ-C3o-alkyl esters of monoethylenically unsaturated C3-Ca carboxylic acids such as acrylic acid, methacrylic acid, dimethacrylic acid, ethacrylic acid, maleic acid, citraconic acid, methylenemalonic acid, allylacetic acid, vinylacetic acid, crotonic acid, fumaric acid, mesaconic acid or itaconic acid. The alkyl radicals also include cycloalkyl radicals. Examples of further comonomers which are excluded are octyl acrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, nonyl acrylate, decyl acrylate, lauryl acrylate, myristyl acrylate, cetyl acrylate, stearyl acrylate, oleyl acrylate, behenyl acrylate, hexyl methacrylate, octyl methacrylate, nonyl methacrylate, decyl methacrylate, lauryl methacrylate, myristyl methacrylate, Cetyl methacrylate, stearyl methacrylate, oleyl methacrylate, behenyl methacrylate or tert-butylcyclohexyl acrylate.

b) N-alkyl or N _t N-dialkyl-substituted carboxylic acid amides of acrylic acid or of methacrylic acid, where the alkyl radicals are Cβ-C 16 -alkyl or cycloalkyl radicals, for example N-stearyl acrylamide, N-stearylmethacrylamide, N-stearyl acrylamide Octylacrylamide, N, N-dioctylacrylamide, N, N-dioctylmethacrylamide, N-cetylacrylamide, N-cetylmethacrylamide, N-dodecylacrylamide, N-dodecylmethacrylamide, N-myristylacrylamide, 2-ethylhexylacrylamide. C)

Vinyl esters of aliphatic carboxylic acids (Cs-Cso-carboxylic acids), for example vinyl esters of octane, Nσnan-, decane, undeca, Laurirv, tridecane, myristic, pafmitin, stearic, arachiπ- or behenic acid or oleic acid.

As further comonomers C), the following copolymerisable monomers (or mixtures thereof) in amounts of 0 to 39 mol%, preferably 1 to 20 mol%, particularly preferably 2 to 10 mol%. be used.

Suitable comonomers C) are, for example, the C 1 -C 7 -alkyl esters, C 1 -C 7 -alkyamides and nitriles of the mono- and dicarboxylic acids mentioned above (as monomer B), for example methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxybutyl acrylate, hydroxyethyl methacrylate, Hydroxypropyimethacrylat, Hydroxyisobutylacrylat, sobutylmethacrylat Hydroxyi-, maleic acid monomethyl ester, maleic acid dimethyl ester, maleic säuremonoethylester, diethyl maleate, acrylamide, methacrylamide, N ₁ N-dimethylacrylamide, N-tert-butyl-acrylamide, N-diethylacrylamide, N-isopropylacrylamide, acrylonitrile, methacrylonitrile.

Other suitable copolymerizable compounds C) are also N-vinylamines, in particular N-vinylamine, and N-vinylimines such as N-vinylimidazole, N-vinyl-2-methylimidazole, N-Viπyl-4-methylimidazole, preferably N-vinylimidazole

Also suitable as monomers C) are also vinyl esters of aliphatic carboxylic acids (C 1 -C 7 -carboxylic acids), for example vinyl acetate, vinyl propionate.

Further suitable monomers C are furthermore the vinyl ethers, for example octadecyl vinyl ether.

As monomer C) it is also possible to use cationic monomers. The cationogenic or cationic groups of these monomers are preferably nitrogen-containing groups, such as primary, secondary and tertiary amino groups, and quaternary ammonium groups. Preferably, the nitrogen-containing groups are tertiary amino groups or quaternary ammonium groups. Charged cationic groups can be prepared from the amine nitrogens either by protonation, eg. With monohydric or polybasic carboxylic acids such as lactic or tartaric acid, or mineral acids such as phosphoric acid, sulfuric acid and hydrochloric acid, or by quaternization, e.g. With alkylating agents such as C ₁ -C ₄ alkyl halides or sulfates. Examples of such alkylation centers! are ethyl chloride, ethyl bromide, methyl chloride, methyl bromide, dimethyl sulfate and Diethylsul- fat. In a preferred embodiment, the monomers C) are used in a charged form for the polymerization. Suitable compounds C) are, for. As the esters of α.ß-ethylenically unsaturated mono- and dicarboxylic acids with amino-acids. Preferred amino alcohols are C 2 -C 12 amino alcohols, which are dialkylated on the amine nitrogen Ci-C _e. As the acid component of these esters are z. For example, acrylic acid, methacrylic acid, fumaric acid, maleic acid, itaconic acid, crotonic acid, maleic anhydride, monobutyl maleate and mixtures thereof. Preference is given to using acrylic acid, methacrylic acid and mixtures thereof. Preferred are N, N-dimethylaminomethyl (rneth) acrylate, N ₁ N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, N ₁ N- dimethylaminopropyl (meth) acrylate, N, N-diethylaminopropyl (meth) acrylate and N ₁ N- dimethylaminocyclohexyl (meth) acrylate.

Suitable monomers C) are furthermore the amides of the abovementioned α, β-ethylenically unsaturated mono- and dicarboxylic acids with diamines which have at least one primary or secondary amino group. Preferred are diamines having a tertiary and a primary or secondary amino group. Preference is given as monomers c) to N- [2- (dimethylamino) ethyl] acrylamide, N- [2- (dimethylamino) ethyl] methacrylamide, N- [3- (dimethylamino) propyl] acrylamide, N- [3- (dimethylamino) propylmethacrylamide, N- [4- (dimethylamino) butyl] acrylamide, N- [4- (dimethylamino) butyl] methacrylamide, N- [2- (diethylamino) ethyl] acrylamide, N- [4- (dimethylamino) cyclohexyl ] acrylamide,

N- [4- (dimethylamino) cyclohexyl] methacrylamide etc used. Particular preference is given to using N- [3- (dimethylamino) propyl] acrylamide and / or N- [3- (dimethylamino) propyl] methacrylamide.

Suitable monomers C) are furthermore N, N-diallylamines and N, N-diallyl-N-alkylamines and their acid addition salts and quaternization products. Alkyl is preferably C 1 -C ₂₄ -alkyl. Preference is given to N, N-diallyl-N-methylamine and N, N-diallyl-N, N-dimethylammonium compounds, such as. As the chlorides and bromides.

Suitable monomers C) are also vinyl-substituted and allyl-substituted nitrogen heterocycles, such as N-vinylimidazole, N-vinyl-2-methylimidazole, vinyl- and allyl-substituted heteroaromatic compounds, such as 2- and 4-vinylpyridine, 2- and 4-allylpyridine , and the salts thereof.

Preferred monomers C) are the N-vinylimidazo! Derivatives of the general formula (II) in which R ¹ to R ^{3 are} hydrogen, C 1 -C ₄ -alkyl or phenyl

(H) Examples of compounds of the general formula (II) are shown in Table 1 below:

Table 1

Me = methyl Ph = phenyl

Preferred examples of monomers C) are 3-methyl-i-vinylimidazolium chloride and methosulfate, dimethyldiallylammonium chloride and

N, N-dimethylaminoethyl methacrylate and N- [3- (dimethylamino) propyl] methacrylamide which have been quaternized by methyl chloride, dimethyl sulfate or diethyl sulfate.

Particularly preferred monomers C) are 3-methyl- ₁ -vinyiimidazolium chloride and methosulfate and dimethyldiallylammonium chloride (DADMAC) _1, very particular preference is given to 3-methyl-1-vinylimidazolium chloride and methosulfate.

Another copolymerizable monomer C) is diallylammonium chloride.

The stated monomers C) can be used according to the invention either individually or in the form of mixtures of several of the compounds mentioned.

The preparation of the copolymers is carried out by known methods, e.g. solution, precipitation, or reverse suspension polymerization using compounds which form radicals under the polymerization conditions.

The Polymerisationstemperatureπ are usually in the range of 30 to 200, preferably 40 to 110 ⁰ C. Suitable initiators are, for example, azo and per-oxy compounds, and the customary redox initiator, such as combinations of Hydrogen peroxide and reducing compounds, for example, sodium sulfite, Natπumbisulfit, Natπumformaldehydsulfoxilat and hydrazine

The copolymers P have K values of at least 7 to 130, preferably 10 to 100, particularly preferably 10 to 50. The K values are determined by H. Fikentscher, Cellulose-Chemie, Volume 13, 58 to 64 and 71 to 74 (1932) in aqueous 0.1 M NaCl solution at 25 ° C., at polymer concentrations which, depending on the K value range, are between 0.1% and 5%, preferably 1%.

A preferred embodiment of the metal oxides according to the invention is characterized in that the metal oxide particles have an average primary particle diameter of 5 to 10,000 nm, preferably 10 to 200 nm, particularly preferably 10 to 50 nm, particle diameter determined by scanning and transmission electron microscopy

Preferred metal oxides in the context of the present invention are titanium dioxide and zinc oxide, particularly preferably zinc oxide

The invention is based on the finding that by a surface modification of nanoparticulate metal oxides with copolymer P, a long-term stability of dispersions of the surface-modified metal oxides, in particular in cosmetic preparations without undesirable pH changes in the storage of these preparations can be achieved.

Another object of the invention is a method for producing a surface-modified nanoparticulate metal oxide, wherein the metal is selected from the group consisting of aluminum, cerium, iron, titanium, zinc and zirconium, by

a. Precipitation of the metal oxide from an aqueous or alcoholic solution of one of its metal salts,

b. Separating the precipitated metal oxide from the aqueous or alcoholic reaction mixture and

c. subsequent drying of the metal oxide,

characterized in that the precipitation of the metal oxide in step a in the presence of a copolymer P is carried out as monomers

A) 1 to 99 ιmol-% of an N-Vιnylamιds and

B) 99 to 1 mol% of a monomer containing, per molecule, a radically polymerizable α, β-ethylenically unsaturated double bond and an amine onogenic and / or anionic group,

contains, with the proviso that the copolymer P no further monomers selected from the group consisting of Cs-Cao alkyl esters of monoethylenically unsaturated CVCβ carboxylic acids, N-alkyl or N, N-Dιalkyl- substituted amides of acrylic acid or may contain methacrylic acid with Cβ-Ciβ-alkyl radicals, or vinyl esters of aliphatic Cβ-Cso-carboxylic acids

The metal salts in process step a may be metal halides, acetates, sulfates or nitrates. Preferred metal salts are halides, for example zinc chloride, titanium tetrachloride and nitrates, for example zinc (II) nyltrate, and acetates, for example zinc (II) acetate.

By way of example, the term "alcoholic solution" means a methanolic or ethanolic solution or else a mixture of water and an alcohol, for example methanol, ethanol or isopropanol

The precipitation of the metal oxide in process step a. can at a temperature in the range of 2O ⁰ C to 100 ⁰ C., preferably in the range of 25 ⁰ C to 40 ⁰ C.

Depending on the metal salt used, the precipitation may be carried out at a pH in the range of 3 to 13. In the case of zinc oxide, the pH at precipitation is in the range of 7 to 11.

The concentration of the metal salts is generally in the range of 0.05 to 1 mol / l, preferably in the range of 0, 1 to 0.5 mol / l, particularly preferably in the range of 0.2 to 0.4 mol / l ,

The fall time is generally 0.2 to 8 hours, preferably 0.2 to 7 hours, more preferably 0.5 to 5 hours, most preferably 1 to 2 hours.

With regard to the definition of the copolymer P used as surface coating in the process according to the invention, both in the general and in the preferred embodiment, reference is made to the description made at the outset.

The present invention is in particular a process for the preparation of surface-modified nanoparticulate zinc oxide by

a. Precipitation of the zinc oxide from an aqueous solution of zinc (II) chloπd,

Zιnk (II) or nιtrat Zιnk (II) acetate at a temperature in the range of 25 to 4O ⁰ C and a pH in the range of 7 to 11 in the presence of an alkali metal hydroxide,

b. Separation of the precipitated zinc oxide from the aqueous reaction mixture and

c. subsequent drying,

characterized in that the precipitation of the zinc oxide in the process seh rode a. in the presence of copolymer P.

The precipitation of the zinc oxide in process step a. For example, by metering in an aqueous solution of a mixture of copolymer P and an alkali metal hydroxide or ammonium hydroxide, in particular NaOH to the aqueous solution of zinc (II) chloride, zinc (II) nitrate or zinc (II) acetate or by simultaneous Zusensieren each an aqueous solution of zinc (II) chloride, zinc (II) nitrate or zinc (II) acetate and an aqueous solution of an alkali metal hydroxide or Ammont- umhydroxids, in particular NaOH to an aqueous solution of the copolymer P.

The separation of the precipitated metal oxide from the aqueous reaction mixture can be carried out in a conventional manner, for example by filtration or centrifugation.

The resulting filter cake can be dried in a conventional manner, for example in a drying oven at temperatures between 40 and 100 ⁰ C, preferably between 50 and 70 ⁰ C under atmospheric pressure to constant weight.

Another object of the present invention is a cosmetic composition containing a surface-coated zinc oxide or a zinc oxide dispersion according to the invention.

Another object of the present invention is the use of surface-modified metal oxide, in particular titanium dioxide or zinc oxide, which are prepared by the process according to the invention:

- for UV protection

as antimicrobial agent

According to a preferred embodiment of the present invention, the surface-modified metal oxide, in particular titanium dioxide or zinc oxide, is redispersible in a liquid medium and forms stable dispersions. This is particularly advantageous because of the dispersions prepared from the zinc oxide according to the invention the further processing need not be redispersed, but can be processed directly.

According to a preferred embodiment of the present invention, the surface-modified metal oxide is redispersible in polar organic solvents and forms stable dispersions. This is particularly advantageous, since this uniform incorporation, for example, in plastics or films is possible.

According to another preferred embodiment of the present invention, the surface-modified metal oxide is redispersible in water and forms stable dispersions there. This is particularly advantageous, since this opens up the possibility of using the material according to the invention, for example in cosmetic formulations, wherein the omission of organic solvents represents a great advantage. Also conceivable are mixtures of water and polar organic solvents.

According to a preferred embodiment of the present invention, the surface-modified metal oxide particles have a diameter of from 10 to 200 nm. This is particularly advantageous since a good re-dispersibility is ensured within this size distribution.

According to a particularly preferred embodiment of the present invention, the metal oxide nanoparticles have a diameter of 10 to 50 nm. This size range is particularly advantageous since, after redispersion of such zinc oxide nanoparticles, the resulting dispersions are transparent and thus, for example, when added to cosmetic formulations, do not affect the coloration. In addition, this results in the possibility for use in transparent films.

If the metal oxides, in particular titanium dioxide or zinc oxide, are to be used as UV absorbers, it is advisable to use particles with a diameter of more than 5 nm, since below this limit, the absorption edge shifts to the short-wave range (L. Brus , J. Phys., Chem. (1986), 90, 2555-2560).

Another object of the present invention is a cosmetic composition containing a surface-modified metal oxide according to the invention, in particular titanium dioxide and / or zinc oxide. This is particularly advantageous since, due to the fine distribution of the metal oxide particles, in particular the zinc oxide particles, these can unfold their skin-soothing effect more effectively.

Another advantage is that when applied to eg the skin due to the small particle size no frictional effect, but a gentle application is possible, which causes a pleasant feeling on the skin. According to a further embodiment of the cosmetic agent, the latter serves to care for or protect the skin, in particular for sun protection or for care in sunlight exposure, and is in the form of an emulsion, a dispersion, a suspension, an aqueous surfactant preparation, a milk, a lotion, a cream , a balm, an ointment, a gel, a granule, a powder, a stick preparation, such as a lipstick, a foam, an aerosol or a spray. Such formulations are well suited for topical preparations. Suitable emulsions are oil-in-water emulsions and water-in-oil emulsions or microemulsions. This is particularly advantageous because the UV-absorbing and soothing action of, for example, zinc oxide can be used simultaneously by use in sunscreens. In addition, the surface-modified metal oxides according to the invention are very suitable for use in sunscreens, since the particles can be produced in a size which makes them appear transparent to the human eye. This results in no white veil on the skin when applied.

A further advantage is the fact that zinc oxide in particular is a broadband UV filter whose UV absorption behavior makes it possible to provide a sunscreen agent which no longer requires any further chemical UV filter substances. Thereby, the risk of skin irritation or allergic reactions by decomposition products of chemical filters or by these substances themselves can be avoided, which greatly increases the general compatibility of such a designed sunscreen. As a rule, the cosmetic agent is used for topical application on the skin. Topical preparations are to be understood as meaning those preparations which are suitable for applying the active ingredients to the skin in fine distribution and preferably in a form absorbable by the skin. For this purpose, e.g. aqueous and aqueous-alcoholic solutions, sprays, foams, foam aerosols, ointments, aqueous gels, emulsions of the O / W or W / O type, microemulsions or cosmetic stick preparations.

According to a preferred embodiment of the cosmetic agent according to the invention, the agent contains a carrier. Preferred as a carrier is water, a gas, a water-based liquid, an oil, a gel, an emulsion or microemulsion, a dispersion or a mixture thereof. The mentioned carriers show a good skin compatibility. Particularly advantageous for topical preparations are aqueous gels, emulsions or microemulsions.

Nonionic surfactants, zwitterionic surfactants, ampholytic surfactants or anionic emulsifiers can be used as emulsifiers. The emulsifiers may be present in the composition according to the invention in amounts of from 0.1 to 10, preferably from 1 to 5,% by weight, based on the composition. As a nonionic surfactant, for example, a surfactant of at least one of the following groups may be used:

Addition products of 2 to 30 moles of ethylene oxide and / or 0 to 5 moles of propylene oxide to linear fatty alcohols having 8 to 22 carbon atoms, to fatty acids having 12 to 22 carbon atoms and alkylphenols having 8 to 15 carbon atoms in the alkyl group;

_{Ci2 /} 18 fatty acid monoesters and diesters of addition products of 1 to 30 mol ethylene oxide onto glycerol;

Glycerol mono- and diesters and sorbitan mono- and diesters of saturated and unsaturated fatty acids of 6 to 22 carbon atoms and their ethylene oxide imidazole products;

Alkyl mono- and oligoglycosides having 8 to 22 carbon atoms in the alkyl radical and their ethoxylated analogs;

Addition products of 15 to 60 moles of ethylene oxide with castor oil and / or hydrogenated castor oil;

Polyol and especially polyglycerol esters, e.g. Polyglycerinpolyricinoleat, Polygl ycerinpoly-12-hydroxystearat or Polyglycerindimerat. Also suitable are mixtures of compounds of several of these classes of substances;

Addition products of 2 to 15 moles of ethylene oxide with castor oil and / or hydrogenated castor oil;

Partial esters based on linear, branched, unsaturated or saturated Cε / 22 fatty acids, ricinoleic acid and 12-hydroxystearic acid and glycerol, polyglycerol, pentaerythritol, dipentaerythritol, sugar alcohols (eg sorbitol), alkyl glucosides (eg methyl glucoside, butyl glucoside , Lauryl glucoside) as well as polyglucosides (eg cellulose);

Mono-, di- and trialkyl phosphates and mono-, di- and / or tri-PEG-alkyl phosphates and their salts;

Lanolin alcohol;

Polysiloxane-polyalkyl-polyether copolymers or corresponding derivatives;

Mixed esters of pentaerythritol, fatty acids, citric acid and fatty alcohol according to DE PS 1165574 and / or mixed esters of fatty acids having 6 to 22 carbon atoms, methyl glucose and polyols, preferably glycerol or polyglycerol and polyalkylene glycols;

Betaine.

Furthermore, zwitterionic surfactants can be used as emulsifiers. Zwitterionic surfactants are those surface-active compounds which carry at least one quaternary ammonium group and at least one carboxy or sulfonate group in the molecule. Particularly suitable zwitterionic surfactants are the so-called betaines, such as N-alkyl-N, N-dimethylammonium glycinates, for example cocoalkyldimethylammonium glycinate, N-acylamino-propyl-N, N-dimethylammonium glycinates, for example cocoacylaminopropyldimethylammonium glycinate, and 2-alkylbenzenesulfonate. 3-carboxy! Methyl-3-hydroxyethyl imidazolines having in each case 8 to 18 C atoms in the alkyl or acyl group, and the cocoacylaminoethylhydroxyethyl carboxymethylglycinate. Particularly preferred is the known under the CTFA name Cocamidopropyl Betaine fatty acid amide derivative.

Also suitable emulsifiers are ampholytic surfactants. Ampholytic surfactants are to be understood as meaning those surface-active compounds which contain, in addition to a C 5-10 alkyl or acyl group in the molecule, at least one free amino group and at least one -COOH or -SCH group and are capable of forming internal salts. Examples of suitable ampholytic surfactants are N-alkylglycines, N-alkylpropionic acids, N-alkylamino-butanoic acids, N-alkyliminodipropionic acids, N-hydroxyethyl-N-alkylamido-propylglycines, N-alkyltaurines, N alkylsarcosines, 2-alkylaminopropionic acids and alkylaminoacetic acids each having about 8 to 18 C atoms in the alkyl group.

Particularly preferred ampholytic surfactants are N-cocoalkylaminopropionate, cocoacylaminoethylaminopropionate and C 12/18 acylsarcosine. In addition to the ampholytic, quaternary emulsifiers are also suitable, those of the esterquat type, preferably methyl-quaternized difatty acid triethanolamine ester salts, being particularly preferred. Furthermore, as anionic emulsifiers, it is possible to use alkyl ether sulfates, monoglyceride sulfates, fatty acid sulfates, sulfosuccinates and / or ether carboxylic acid.

Guerbet alcohols based on fatty alcohols having 6 to 18, preferably 8 to 10, carbon atoms, esters of linear C 6 -C 22 -fatty acids with linear C 6 -C ₂ 2-fatty alcohols, esters of branched Cs-C ₁₃ -carboxylic acids with linear C ₆ - C22 fatty alcohols, esters of C6-C22 linear fatty acids with branched alcohols, in particular 2-ethylhexanol, esters of linear and / or branched fatty acids with polyhydric alcohols (such as propylene glycol, dimerdiol or trimer triol) and / or Guerbet alcohols, triglycerides based on Ce-Cio fatty acids, liquid mono- / di-, triglyceride mixtures based on Ce-Cis fatty acids, esters of Ce-C22 fatty alcohols and / or Guerbet alcohols with aromatic carboxylic acids, in particular benzoic acid, esters of C≥- C ^ dicarboxylic acids with linear or branched alcohols with 1 to 22 carbon atoms or polyols having 2 to 10 carbon atoms and 2 to 6 hydroxyl groups, vegetable oils, branched primary alcohols, substituted cyclohexyls, linear Ce-C22 fatty alcohols, Guerbet carbonates, esters of benzoic acid with linear and / or branched Ce C2 ₂ alcohols (for example Finsolv TN ^φ), dialkyl ethers, ring opening products of epoxidized Feüsäureestern with polyols, silicone oils and / or aliphatic or naphthenic hydrocarbons. It is also possible to use silicone compounds as oil particles, for example dimethylpolysiloxanes, methylphenylpolysiloxanes, cyclic silicones and also amino, fatty acid, alcohol, polyether, epoxy, fluorine, alkyl and / or glycoside-modified silicone rubbers. Compounds which may be both liquid and resinous at room temperature. The oil bodies may be present in the compositions according to the invention in amounts of from 1 to 90, preferably from 5 to 80, and in particular from 10 to 50,% by weight, based on the composition.

According to a particularly preferred embodiment, the composition according to the invention contains further UV light protection filters in the form of soluble compounds or other pigments.

Although it is possible, as already described above, with the aid of the zinc oxide particles according to the invention! a sunscreen center! To create, which achieves good UV absorption properties without further UV filter substances, it may be desirable in individual cases to add to the cosmetic product or the sunscreen more UV filter substances. This can e.g. be necessary if a special emphasis should be placed on filter performance. One or more further UV light protection filters can be added to the composition according to the invention.

In the case of soluble compounds, UV light protection filters are organic substances capable of absorbing ultraviolet rays and absorbing the absorbed energy in the form of longer wavelength radiation, e.g. Heat, give it up again. The organic substances may be oil-soluble or water-soluble.

As oil-soluble UV-B filters, e.g. the following substances are used;

3-benzylidene camphor and its derivatives, e.g. 3- (4-methylbenzylidene) camphor;

4-aminobenzoic acid derivatives, preferably 2-ethylhexyl 4- (dimethylamino) benzoate, 2-octyl 4- (dimethylamino) benzoate and 4- (dimethylamino) benzoic acid ester;

Esters of cinnamic acid, preferably 2-ethylhexyl 4-methoxycinnamate, 4-propyl methoxy cinnamate, isoamyl 4-methoxycinnamate, 4-isoacetyl methoxycinnamate, 2-cyano-3-phenylcinnamic acid 2-ethylhexyl ester (octocrylene); Esters of salicylic acid, preferably 2-ethylhexyl salicylate, 4-isopropylbenzyl salicylate, homomenthyl salicylate;

Derivatives of benzophenone, preferably 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxy-4'-methylbenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone;

Esters of benzalmalonic acid, preferably di-2-ethylhexyl 4-methoxybenzmalonate;

Triazine derivatives such as 2,4,6-Trianiliπo- (p-carbo-2'-ethyl-1 ^' hexyloxy) -1,3 _J 5-triazine (octyl triazone) and dioctyl butamido triazone (Uvasorb ^® HEB).

Propane-1,3-diones, e.g. 1- (4-tert-butylphenyl) -3- (4'-methoxyphenyl) propane-1,3-dione.

Suitable water-soluble substances are:

2-phenylbenzimidazole-5-sulphonic acid and its alkali metal, alkaline earth metal, ammonium, alkylammonium, alkanolammonium and glucammonium salts;

Sulfonic acid derivatives of benzophenones, preferably 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid and its salts;

Sulfonic acid derivatives of the 3-benzylidene camphor, e.g. 4- {2-Oxo-3-bornylidenemethyl) beπzolsulfonsäure and 2-methyl-5- (2-oxo-3-borπyliden) sulfonic acid and salts thereof.

Especially preferred is the use of esters of cinnamic acid, preferably 4-methoxycinnamic acid 2-ethylhexyl ester, 4-methoxycinnamic acid isopentyl ester, 2-cyano-3-phenylcinnamic acid 2-ethylhexyl ester (octocrylene).

Furthermore, the use of derivatives of benzophenone, in particular 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxy-4 ^v -methylbenzophenoπ, 2,2'-dihydroxy-4-methoxybenzophenone and the use of propane-1, 3-diones, such as 1- (4-tert-butylphenyl) -3- (4-methethoxyphenyl) propane-1,3-dione.

Typical UV-A filters are:

Derivatives of benzoylmethane, such as 1- (4'-tert-butylphenyl) -3- (4'-methoxyphenyl) propane-1,3-dione, 4-tert-butyl-4'-methoxydibenzylmethane or 1 -Phenyl-3- (4'-isopropylpheny [) -propane-1,3-dione; Amino-hydroxy-substituted derivatives of benzophenones such as N, N-diethylamino-hydroxybenzoyl-n-hexyl benzoate.

Of course, the UV-A and UV-B filters can also be used in mixtures.

As other light stabilizers, however, other insoluble pigments, e.g. finely disperse metal oxides or salts such as titanium dioxide, iron oxide, aluminum oxide, cerium oxide, zirconium oxide, silicates (talc), barium sulfate and zinc stearate. The particles should have an average diameter of less than 100 nm, preferably between 5 and 50 nm and in particular between 15 and 30 nm.

In addition to the two aforementioned groups of primary light stabilizers, it is also possible to use secondary light stabilizers of the antioxidant type which interrupt the photochemical reaction chain which is triggered when UV radiation penetrates into the skin. Typical examples are superoxide dismutase, tocopherols (vitamin E) and ascorbic acid (vitamin C).

The total amount of light stabilizer in the sunscreen according to the invention is usually from 1 to 20, preferably 5 to 15 wt .-%. As such, the composition according to the invention may contain from 1 to 95, preferably from 5 to 80, and in particular from 10 to 60,% by weight of water.

According to a particularly preferred embodiment, the cosmetic composition according to the invention further contains nourishing substances, other cosmetic active ingredients and / or auxiliaries and additives.

Skin-moisturizing agents, antimicrobial substances and / or deodorant or antiperspirant substances are used in particular as weathering cosmetic active ingredients. This has the advantage that it is possible to obtain further desired effects which contribute to the care or treatment of the skin or, for example, increase the sense of well-being of the user of the cosmetic composition when using this composition.

Thus, in the cosmetic composition in addition to the carrier, the surface-modified zinc oxide, water and physiologically suitable solvents, among other nourishing ingredients such as oils, waxes, fats, moisturizers, thickeners, emulsifiers and fragrances may be included. A high proportion of nourishing substances is particularly advantageous for topical prophylactic or cosmetic treatment of the skin. It is particularly advantageous if the composition contains further care components in addition to the animal and vegetable fats and oils, which in many cases also have care properties. The group of care active substances which can be used includes, for example: fatty alcohols having 8-22 C atoms, in particular fatty alcohols of natural fatty acids; animal and vegetable protein hydrolysates, in particular elastin, collagen, keratin, milk protein, soy protein, silk protein, oat protein, pea protein, almond protein and wheat protein hydrolysates; Vitamins and vitamin precursors, in particular those of vitamin groups A and B; Mono-, di- and oligosaccharides; Pflanzeπextrakte; Honey extracts; ceramides; phospholipids; Vaseline, paraffin and silicone oils; Fatty acid and fatty alcohol esters, in particular the monoesters of the fatty acids with alcohols having 3 to 24 carbon atoms. The preferred vitamins, provitamins or vitamin precursors to be used in the composition according to the invention include, among others:

Vitamins, provitamins and vitamin precursors from groups A, C, E and F, in particular 3,4-didehydroretinol, ß-carotene (provitamin of vitamin A), ascorbic acid (vitamin C), and the palmitic acid esters, glucosides or phosphates of ascorbic acid, tocopherols , in particular α-tocopherol and its esters, eg the acetate, nicotinate, phosphate and succinate; vitamin F, which is understood as meaning essential fatty acids, especially linoleic acid, linolenic acid and arachidonic acid;

Vitamin A and its derivatives and provitamins advantageously show a particular skin-smoothing effect.

The preferred vitamins, provitamins or vitamin precursors of the vitamin B group or derivatives thereof and derivatives of 2-furanone to be used in the composition according to the invention include:

Vitamin Bi, common name thiamine, chemical name 3 - [(4'-amino-2'-methyl-5'-pyrimidinyl) methyl] -5- (2-hydroxyethyl) -4-methylthiazolium chloride. Thiaminhydrochlohd is preferably used in amounts of 0.05 to 1 wt .-%, based on the total agent.

Vitamin B2, common name riboflavin, chemical name 7,8-dimethyl-10- {1-D-ribityl) -benzo [g] pteridine-2,4 (3H, 10H) -dione. In free form riboflavin z. As in whey, other riboflavin derivatives can be isolated from bacteria and yeasts. A stereoisomer of riboflavin which is likewise suitable according to the invention is lyxoflavin which can be isolated from fishmeal or liver and which instead of D-ribity! carries a D-Arabityl residue. Riboflavin or its derivatives are preferably used in amounts of from 0.05 to 1% by weight, based on the total agent. Vitamin B3. Under this name, the compounds nicotinic acid and nicotinamide (niacinamide) are often performed. Preferred according to the invention is the nicotinic acid amide, which is preferably present in the agents according to the invention in amounts of from 0.05 to 1% by weight, based on the total agent.

Vitamin Bs (pantothenic acid and panthenol). Panthenol is preferably used. Derivatives of panthenol which can be used according to the invention are, in particular, the esters and ethers of panthenol and also cationically derivatized panthenols. In a further preferred embodiment of the invention, it is also possible to use derivatives of 2-furanone in addition to pantothenic acid or panthenol. Particularly preferred derivatives are the commercially available substances dihydro-3-hydroxy-4,4-dimethyl-2 (3H) -furanone with the trivial name pantolactone (Merck), 4 hydroxymethyl-γ-butyrolactone (Merck), 3,3-dimethyl 2-hydroxy-γ-butyrolactone (Aldrich) and 2,5-dihydro-5-methoxy-2-furanone (Merck), expressly including all stereoisomers.

Advantageously, these compounds impart moisturizing and soothing properties to the cosmetic composition according to the invention.

The said compounds of the vitamin Bs type and the 2-furanone derivatives are contained in the agents according to the invention preferably in a total amount of 0.05 to 10 wt .-%, based on the total agent. Total amounts of 0.1 to 5 wt .-% are particularly preferred.

Vitamin Be, which is not understood to be a uniform substance but the derivatives of 5-hydroxymethyl-2-methylpyridin-3-ol known under the common names pyridoxine, pyridoxamine and pyridoxal. Vitamin Bs is preferably present in the agents according to the invention in amounts of from 0.0001 to 1.0% by weight, in particular in amounts of from 0.001 to 0.01% by weight.

Vitamin B7 (biotin), also known as vitamin H or "skin vitamin". Biotin is (3aS, 4S, 6aR) -2-oxohexahydrothienol [3,4-d] imidazole-4-valeric acid. Biotin is preferably present in the compositions according to the invention in amounts of from 0.0001 to 1.0% by weight, in particular in amounts of from 0.001 to 0.01% by weight.

Panthenol, pantolactone, nicotinamide and biotin are very particularly preferred according to the invention.

Hiifs and additives are substances that are suitable for improving the aesthetic, performance and / or cosmetic properties, such as z.6. Co-emulsifiers, organic solvents, superfatting agents, stabilizers, antioxidants, waxes or greases, bodying agents, thickeners, Tanning agents, vitamins, cationic polymers, biogenic agents, preservatives, Hydrσtope, solubilizers, dyes and fragrances.

For example, the following auxiliaries and additives can be used:

- allantoin,

- Aloe Vera,

- bisabolol,

Ceramides and pseudoceramides,

Antioxidants advantageously improve the stability of the compositions of the invention. Antioxidants are, for example, amino acids (eg glycine, histidine, tyrosine, tryptophan) and their derivatives, imidazole and imidazole derivatives (eg urocaninic acid), peptides such as D, L-carnosine, D-carnosine, L-carnosine and their derivatives (eg. Anserine), carotenoids, carotenes (eg, 6-α-carotene, β-carotene, lycopene) and their derivatives, lipoic acid and derivatives thereof (eg dihydrolipoic acid), aurothioglucose, propylthiouracil and other thio compounds (eg thioglycerol, thiosorbitol , Thioglycolic acid, thi redoxin, glutathione, cysteine, cystine, cystamine and their glycosyl, N-acetyl, methyl, ethyl, propyl, amyl, butyl, lauryl, palmitoyl, oleyl, γ Linoleyl, cholesteryl and glyceryl esters) and their salts, dilauryl thiodipropionate, distearyl thiodipropionate, thiodipropionic acid and derivatives thereof (esters, ethers, peptides, lipids, nucleotides, nucleosides and salts) and sulfoximine compounds (for example, butynin sulfoximines, Homocysteine sulfoximine, buthionine sulfone, penta-, hexa-, Heptathionin- sulfoximine) in very low tolerated dosages (eg. Pmol / kg to pmol / kg), furthermore metal chelators (eg α-hydroxyfatty acids, EDTA, EGTA, phytic acid, lactoferrin), α-hydroxy acids (eg citric acid, lactic acid, malic acid), humic acids, bile acid, bile extracts , Gallic acid esters (eg propyl, octyl and dodecyl gallate), flavonoids, catechins, bilirubin, bievedin and their derivatives, unsaturated fatty acids and their derivatives (eg γ-linolenic acid, linoleic acid, arachidonic acid, oleic acid), folic acid and derivatives thereof, Hydroquinone and its derivatives (eg arbutin), ubiquinone and ubiquinol and their derivatives, vitamin C and its derivatives (for example, ascorbyl palmitate, stearate, dipalmitate, acetate, magnesium ascorbyl phosphates, sodium and magnesium ascorbate, Disodium ascorbyl phosphate and sulfate, potassium ascorbyl tocopheryl phosphate, chitosan ascorbate), isoascorbic acid and its derivatives, tocopherols and their derivatives (eg tocopheryl acetate, linoleate, oleate and succinate, tocophereth-5, tocophereth-10, tocophereth-12, To cophereth-18, tocophereth-50, tocopherolan), vitamin A and derivatives (e.g. Vitamin A palmitate), the coniferyl benzoate of benzoin, rutin, rutinic acid and its derivatives, dinathumrutinyldisulfate, cinnamic acid and its derivatives (eg, ferulic acid, ethylferlate, caffeic acid), kojic acid, chitosan glycolate and salicylate, butylhydroxytoluene, butylhydroxyanisole, Nordihydroguaiakharzsäure, Nordihy droguajaretic acid, trihydroxybutyrophenone, uric acid and its derivatives, mannose and its derivatives, zinc and zinc derivatives (eg ZnO, ZnSO 4), selenium and selenium derivatives (eg selenomethionine), stilbenes and stilbene derivatives (e.g. B. Stilbenoxid, trans- Stiibenoxid).

According to the invention, suitable derivatives (salts, esters, sugars, nucleotides, nucleosides, peptides and lipids) and mixtures of said active substances or plant extracts (for example tea tree oil, rosemary extract and rosmarinic acid) containing these antioxidants can be used. Preferred lipophilic, oil-soluble antioxidants from this group are tocopherol and its derivatives, gallic acid esters, flavonoids and carotenoids, and butylhydroxytoluene / anisole. As water-soluble antioxidants are amino acids, eg. As tyrosine and cysteine and their derivatives and tanning agents, especially those of plant origin are preferred. The total amount of the antioxidants in the cosmetic compositions according to the invention is 0.001-20% by weight, preferably 0.05-10% by weight, in particular 0.1-5% by weight and very particularly preferably 0.1-2% by weight. -%.

Triterpenes, in particular triterpenic acids such as ursolic acid, rosmarinic acid, betulinic acid, boswellic acid and bryonic acid,

Monomeric catechins, especially catechin and epicatechin, leucoanthocyanidins, catechin polymers (catechin tannins) and gallotannins,

Thickener, z. Gelatin, plant gums such as agar, guar gum, alginates, xanthan gum, gum arabic, karaya gum or locust bean gum, natural and synthetic clays and phyllosilicates, e.g. B. bentonite, hectorite, montmorillonite or Laponite ^® , fully synthetic hydrocolloids such as polyvinyl alcohol, and also Ca, Mg or Zn soaps of fatty acids,

Vegetable glycosides,

Structurants such as maleic acid and lactic acid,

dimethyl isosorbide,

Alpha, beta and gamma cyclodextrins, in particular for the stabilization of retinol,

Solvents, swelling and penetrating substances such as ethanol, isopropanol, ethylene glycol, propylene glycol, propylene glycol monoethyl ether, glycerol and diethylene glycol, carbonates, bicarbonates, guanidines, ureas and primary, secondary and tertiary phosphates

Perfume oil, pigments and dyes for staining the agent, Substances for adjusting the pH, for example α- and β-hydroxycarboxylic acids,

Complexing agents such as EDTA, NTA, β-alaninediacetic acid and phosphoric acids,

Opacifiers such as latex, styrene / PVP and styrene / acrylamide copolymers,

Pearlescent oils such as ethylene glycol mono- and distearate and PEG-3-distearate,

Propellants such as propane-butane mixtures, N ₂ O, dimethyl ether, CO ₂ and air.

The addition of allantoin, bisabolol and / or aloe vera also in the form of extracts to the cosmetic compositions according to the invention further improves the skin-soothing, moisturizing and skin care properties of the formulations and is therefore particularly preferred.

As further ingredients, the cosmetic composition according to the invention may contain, in minor amounts, further surfactants compatible with the other ingredients.

Typical examples of anionic surfactants are soaps, alkylbenzenesulfonates, alkanesulfonates, olefinsulfonates, alkyl ether sulfonates, glycerol ether sulfonates, α-methyl ester sulfonates, sulfo fatty acids, alkyl sulfates, fatty alcohol ether sulfates, glycerol ether sulfates, hydroxy mixed ether sulfates, fatty acid amide (ether) sulfates, mono- and dialkyl sulfonates. succinates, mono- and dialkylsulfosuccinamates, sulfotriglycerides, amide soaps, ether carboxylic acids and their salts, fatty acid isethionates, fatty acid sarcosinates, fatty acid taurides, N-acylamino acids such as acyl lactylates, acyl tartrates, acylglutamates and acylaspartates, alkyl oligoglucoside sulphates, protein fatty acid condensates (especially vegetable products Wheat base) and alkyl (ether) phosphates.

If the anionic surfactants contain polyglycol ether chains, these may have a conventional, but preferably a narrow homolog distribution.

Typical examples of nonionic surfactants are fatty alcohol polyglycol ethers, fatty acid polyglycol ethers, fatty acid amide polyglycol ethers, fatty amine polyglycol ethers, alkoxylated triglycerides, mixed ethers or optionally mixed partially oxidized alk (en) yloligoglycosides or glucuronic acid derivatives, fatty acid N-alkyl glyucamides, protein hydrolysates (in particular vegetable products based on wheat). , Polyol fatty acid esters, sugar esters, sorbitan esters, polysorbates and amine oxides. If the nonionic surfactants contain polyglycol ether chains, these may have a conventional, but preferably a narrow homolog distribution. Typical examples of cationic surfactants are quaternary ammonium compounds and esterquats, especially quaternized fatty acid triaikanotamine ester salts.

Typical examples of amphoteric or zwitterionic surfactants are alkyl betaines, alkyl amidobetaines, aminopropionates, aminoglycinates, imidazolinium betaines and suifobetaines.

According to another particularly preferred embodiment, the cosmetic center according to the invention! used as a sunscreen. The resulting benefits have already been explained in detail.

The use of the zinc oxide dispersions according to the invention is also possible in particular in hair cosmetics such as shampoos, conditioners, rinses, hair lotions, hair gels, hair sprays etc. In particular leave-on products which remain on the hair or scalp after application are particularly well suited. The zinc oxide applied to the scalp and the hair can thus also act there as a UV protection agent or unfold its skin-soothing effect on the scalp.

According to a preferred embodiment of the cosmetic agent according to the invention, the cosmetic agent is applied topically to the surface of the body to be treated or protected. This form of application is particularly advantageous because it is easy to handle, so that incorrect dosages are largely excluded. Furthermore, an additional nourishing effect for the skin can be achieved. In addition, if only a few body parts are exposed to solar radiation, the sunscreen can only be applied specifically to these parts of the body.

Another object of the present invention is the use of the present invention surface-modified metal oxides for UV protection. This is particularly advantageous because due to the fineness of, for example, the surface-modified zinc oxide and the good distribution, a particularly high UV absorption is achieved.

A further subject of the present invention is the use of the surface-modified metal oxides according to the invention, in particular of zinc oxide as antimicrobial active ingredient. The use of these particles is particularly advantageous for this purpose, because due to the fineness of the particles and the resulting large surface area, the antimicrobial effect is greatly improved and on the other hand, due to the good dispersing properties of the material, the zinc oxide is present in finely divided form. Thus, the zinc oxide can be easily used in various dosage forms such as creams, skin milk, lotions or Tonics.

Another object of the present invention is a pharmaceutical agent containing a surface-modified metal oxide according to the invention. This phar- Medicinal agent is characterized by the fact that due to the fineness of the particles, the pharmaceutical activity is greatly increased.

In addition, the pharmaceutical agent according to the invention has the advantage that due to the good long-term stability already described above, for example, the zinc oxide dispersions can be dispensed with the addition of stabilizers, which prevent segregation. Thus, in addition, the compatibility of the pharmaceutical agent is increased.

The invention will be explained in more detail with reference to the following examples.

Production of surfaces of modified zinc oxide

Example 1 :

500 ml of a 0.4M NaOH solution, which in addition 2 g of a copolymer P of 94 mol% vinylpyrrolidone and 6 mol% of sodium acrylate, were heated to 40 ⁰ C and within 6 min to 500 ml of a likewise at 4O ⁰ C heated 0.2 M Zn (ll) acatat solution dosed. The precipitate was stirred for 2 hours at 4O ⁰ C. The precipitated product copolymer-surface-modified was filtered off and dried at room temperature.

Example 2:

500 ml of a 0.4M NaOH solution, which in addition 2 g of a copolymer P of 94.15 mol% of N-vinylcaprolactam and 5.85 mol% of sodium acrylate, were heated to 4O ⁰ C and within 6 min to 500 ml of a likewise heated to 40 ⁰ C 0.2 M Zn (II) acatate solution. The precipitate was stirred for 2 hours at 40 ⁰ C. The precipitated product copolymer-surface-modified was filtered off and dried at room temperature.

Examples of cosmetic formulations

General procedure for the preparation of the preparations according to the invention as emulsions

The respective phases A and C were heated separately to about 851ΪC. Subsequently, phase C and the metal oxide were stirred into phase A with homogenization. After brief Nachhomogenisieren the emulsion was cooled with stirring to room temperature and filled. All amounts are based on the total weight of the preparations. Example 3:

Emulsion A, comprising 3 wt .-% Uvinui ^® T150 and 4 wt .-% of zinc oxide prepared according to Example 1

Example 4:

Emulsion B containing 3 wt -% Uvinui ^® T150, 2 wt .-% Uvinui ^® A Plus and 4 wt .-% of zinc oxide prepared according to Example 1

Example 5:

Emulsion A _r containing 3 wt .-% Uvinul ^® T150 and 4 wt .-% of zinc oxide prepared according to Example 2

Example 6:

Emulsion B ₁ containing 3 wt .-% Uvinul ^® T150, 2 wt, -% Uvinul ^® A Plus and 4 wt .-% of zinc oxide prepared according to Example 2

Claims

claims

1. Surface-modified nanoparticulate metal oxides, wherein the metal is selected from the group consisting of aluminum, cerium, iron, titanium, zinc and zirconium, characterized in that the surface modification comprises a coating comprising a copolymer P containing as monomers

A) 1 to 99 mol% of an N-vinylamide and

B) 99 to 1 mol% of a monomer containing, per molecule, a free-radically polymerizable α, β-ethylenically unsaturated double bond and an anionogenic and / or anionic group,

with the proviso that the copolymer P no further monomers selected from the group consisting of Cs-C3o-alkyl esters of monoethylenically unsaturated C ₃ -C ₈ carboxylic acids, N-alkyl or N, N-dialkyl-substituted Ami - May contain the acrylic acid or methacrylic acid with Ca-Ciβ-alkyl radicals, or vinyl esters of aliphatic Ca-C3o-carboxylic acids.

2. Surface-modified metal oxides according to claim 1, characterized in that the surface modification comprises a coating comprising a copolymer containing as component A) 50 to 99 mol% of N-vinylpyrrolidone and as component B) 1 to 50 mol% of acrylic acid.

3. Surface-modified metal oxides according to claim 1 or 2, characterized in that the metal oxide particles have an average primary particle diameter of 5 to 10,000 nm.

4. Metal oxides according to one of claims 1 to 3, characterized in that it is surface-modified zinc oxide.

5. A method for producing a surface-modified nanoparticulate metal oxide, wherein the metal is selected from the group consisting of aluminum, cerium, iron, titanium, zinc and zirconium, by

b. Separation of the precipitated metal oxide from the aqueous or alcoholic reaction mixture and c. subsequent drying of the metal oxide,

characterized in that the precipitation of the metal oxide in process step a. in the presence of a copolymer P is carried out as monomers

A) 1 to 99 mol% of an N-vinylamide and

with the proviso that the copolymer P no further monomers selected from the group consisting of Cs-C3o alkyl esters of monoethylenically unsaturated C ₃ -Ce carboxylic acids, N-alkyl or N, N-dialkyl substituted Amides of acrylic acid or methacrylic acid with Cg-Ciβ-

Alkyl radicals, or vinyl esters of aliphatic Ce-C3o-carboxylic acids may contain.

6. The method according to claim 5, characterized in that the precipitation takes place in the presence of a copolymer P, comprising as component A) from 50 to 99 mol% of N-vinylpyrrolidone and as component B) from 1 to 50 mol% of acrylic acid,

7. Process according to claim 5 or 6, characterized in that the metal salts are metal halides, acetates, sulfates or nitrates.

8. The method according to any one of claims 5 to 7, characterized in that the precipitation takes place at a temperature in the range of 20 ^D C to 100 ⁰ C.

9. The method according to any one of claims 5 to 8, characterized in that the precipitation takes place at a pH in the range of 3 to 12.

10. The method according to any one of claims 5 to 9 for the preparation of surface-modified nanoparticulate zinc oxide.

11. The method according to claim 10, characterized in that the precipitation of the

Zänkoxids in process step a. from an aqueous solution of zinc (II) chloride, zinc (II) nitrate or zinc (II) acetate at a temperature in the range of 25 to 40 ⁰ C and a pH in the range of 7 to 1 1 in the presence of a copolymer P he follows.

12. Use of surface-modified nanoparticulate metal oxides, defined according to any one of claims 1 to 4, for the preparation of cosmetic preparations.

13. Use according to claim 12 for the production of cosmetic sunscreen preparations.

14. Cosmetic preparations containing surface-modified nanoparticulate metal oxides, defined according to one of claims 1 to 4.