WO2001093822A2

WO2001093822A2 - Aqueous dispersions of nano-particulate uv-filters

Info

Publication number: WO2001093822A2
Application number: PCT/EP2001/006076
Authority: WO
Inventors: Hans Dolhaine; Michael Neuss; Marcel Roth; Christine Schröder
Original assignee: Henkel Kommanditgesellschaft Auf Aktien
Priority date: 2000-06-08
Filing date: 2001-05-29
Publication date: 2001-12-13
Also published as: DE10027950B4; AU2001276349A1; DE10027950A1; WO2001093822A3

Abstract

The invention relates to aqueous suspensions of solid particles of UV-filters, whereby said particles have an average diameter which ranges between 10 and 500 nm and contain at least one UV-filter and preferably at least one surface modifying agent. The suspensions are suitable for producing cosmetic preparations, in particular sunscreens with an improved UV-protective action, an extremely stable formulation and whose UV-protection is water-resistant.

Description

Aqueous dispersions of nanoparticulate light protection filters

The invention relates to aqueous suspensions of solid particles of light protection filters, the particles having an average diameter in the range from 10 to 500 nm and containing at least one light protection filter and preferably at least one surface modification agent.

Sun protection filters (synonymous: sun protection factors or UV filters) are substances that are able to absorb ultraviolet rays and to release the absorbed energy in the form of longer-wave radiation, eg heat. A large number of substances of this type are known from the prior art and are used in particular in sunscreens, but also in other cosmetic products for hair and body care, in order to counteract the harmful effects of sunlight, such as erythema, hyperkeratosis, skin aging and in the worst case Counteract skin cancer. A corresponding overview of suitable UV light protection filters has been published by P.Finkel in SÖFW-Journal 122, 543 (1996); for the use of nanoparticulate inorganic light protection pigments, see C.Müller-Goymann et al. in perf. Kosm. 79, 24 (1998). There is an obvious need among consumers for effective sun protection, ie the longest possible exposure time, which generally requires a particularly high proportion of light protection filters in the formulation. This is a double problem for the production of such products, since larger amounts of light protection filters are difficult to incorporate into stable emulsions and, moreover, these even more expensive. Such compositions are also often judged by users to be cosmetically unsatisfactory because they feel sticky and fat, ie uncomfortable.

For the production of sunscreens which have sufficient adhesive strength on the body surface and in particular good water resistance, it is also advantageous to use light-protection filters which are sparingly soluble in water, which makes the formulation of these preparations considerably more difficult. This applies particularly to sunscreens based on O / W emulsions or other aqueous bases.

EP-B1 0 666 075 describes cosmetic or dermatological preparations for UV protection of the skin or hair which contain an aqueous dispersion of solid particles of a homopolymer filter with an average diameter between 10 and 400 nm. In the homopolymer filter, UV-absorbing functional groups are chemically bound to a polymer structure. Special polymer-bound light protection filters are therefore required to formulate such preparations, and the well-known conventional raw materials available on the market cannot be used. In addition, the use of organic solvents such as 1,2-dichloroethane is required to prepare the dispersions, which is toxicologically unsafe and undesirable for cosmetic purposes.

There was therefore a need to make available cosmetic preparations which are easy to formulate, have a high sun protection effect and have high water resistance.

The invention relates to an aqueous suspension of solid particles of light protection filters, the particles having an average diameter in the range from 10 to 500 nm and contain at least one light protection filter and preferably at least one surface modification agent.

Sunscreen filters which can be used in the sense of the invention are to be understood as meaning oil-soluble or water-soluble substances which are solid at room temperature and which are able to absorb ultraviolet rays and absorb the energy absorbed in the form of longer-wave radiation, e.g. To give off heat again. The light protection filters that can be used according to the invention are preferably meltable without decomposition and are present as monomers, i. H. they are not polymers. Depending on the absorption spectrum of the light protection filter, a distinction is made between UV-A, UV-B and broadband filters.

The UV-B filters can be oil-soluble or water-soluble. As oil-soluble substances such. B. To name:

3-benzylidene camphor or 3-benzylidene norcampher and its derivatives, e.g. 3- (4-methylbenzylidene) camphor as described in EP-B1 0693471;

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

Esters of cinnamic acid, preferably 4-methoxycinnamic acid 2-ethylhexyl ester, 4-methoxycinnamic acid propyl ester, 4-methoxycinnamic acid isoamyl ester 2-cyano-3,3-phenylcinnamic acid 2-ethylhexyl ester (octocrylene);

• esters of salicylic acid, preferably salicylic acid 2-ethylhexyl ester, salicylic acid 4-isopropylbenzyl ester, salicylic acid homomethyl ester;

• derivatives of benzophenone, preferably 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-meth-oxy-4'-methylbenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone;

• Esters of benzalmalonic acid, preferably di-2-ethylhexyl 4-methoxybenzmalonate; • Triazine derivatives, such as, for example, 2,4,6-trianilino- (p-carbo-2'-ethyl-1'-hexyloxy) -1, 3,5-triazine, octyl triazone, as described in EP-A1 0818450 , and Dioctyl Butamido Triazone (Uvasorb® HEB) ;;

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

• Ketotricyclo (5.2.1.0) decane derivatives, as described in EP-B1 0694521.

Examples of suitable water-soluble substances are:

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

• sulfonic acid derivatives of benzophenones, preferably 2-hydroxy-4-methoxy-benzophenone-5-sulfonic acid and its salts;

Sulfonic acid derivatives of 3-benzylidene camphor, e.g. 4- (2-oxo-3-bornylidene methyl) benzenesulfonic acid and 2-methyl-5- (2-oxo-3-bomylidene) sulfonic acid and their salts.

Derivatives of benzoyl methane, such as 1- (4'-tert-butylphenyl) -3- (4'-methoxyphenyl) prppan-1, 3-dione, 4-, are particularly suitable as typical UV-A light protection filters. tert-Butyl-4'-methoxydibenzoyl-methane (Parsol 1789), or 1-phenyl-3- (4'-isopropylphenyl) propane-1,3-dione.

The UV-A, UV-B and broadband filters can of course also be used in mixtures.

It is preferred according to the invention if the light protection filters in the form of the nanoparticulate suspension are oil-soluble. Light protection filters are particularly preferably selected from the group formed by 3-benzylidene camphor or 3-benzylidene norcampher and its derivatives, 4-aminobenzoic acid derivatives, cinnamic acid esters, salicylic acid esters, benzalmalonic acid esters, benzophenone derivatives, benzoylmethane derivatives, triazine derivatives, propane-1,3 -diones, ketotricyclo (5.2.1.0) decane derivatives and mixtures thereof. In the sense of the invention it is further preferred if the light protection filter particles are coated with one or more surface modification agents. Surface modification agents are understood to mean substances which physically adhere to the surface of the nanoparticles, but preferably do not react chemically with them. The individual molecules of the surface modification agents adsorbed on the surface are essentially free of intermolecular bonds with one another. Surface modifiers are to be understood in particular as dispersants. Dispersants are also known to the person skilled in the art, for example, under the terms emulsifiers, protective colloids, wetting agents and detergents.

Examples of suitable surface modifiers are emulsifiers of the nonionic surfactant type from at least one of the following groups:

(1) Adducts of 2 to 30 moles of ethylene oxide and / or 0 to 5 moles of propylene oxide with linear fatty alcohols with 8 to 22 C atoms, with fatty acids with 12 to 22 C atoms and with alkylphenols with 8 to 15 C atoms in the alkyl group;

(2) Cι _{2 /} i ₈ fatty acid monoesters and diesters of adducts of 1 to 30 moles of ethylene oxide with glycerol;

(3) glycerol monoesters and diesters and sorbitan monoesters and diesters of saturated and unsaturated fatty acids having 6 to 22 carbon atoms and their ethylene oxide addition products;

(4) alkyl mono- and oligoglycosides with 8 to 22 carbon atoms in the alkyl radical and their ethoxylated analogs;

(5) adducts of 2 to 60 moles of ethylene oxide with castor oil and / or hardened castor oil;

(6) polyol and in particular polyglycerol esters, such as polyglycerol polyricinoleate, polyglycerol poly-12-hydroxystearate or polyglycerol dimerate. Likewise Mixtures of compounds from several of these classes of substances are suitable;

(7) _{partial esters} based on linear, branched, unsaturated or saturated C _6/22 fatty acids, ricinoleic acid and 12-hydroxystearic acid and glycerin, polyglycerin, pentaerythritol, dipentaerythritol, sugar alcohols (e.g. sorbitol), alkyl glucosides (e.g. methyl glucoside, butyl glucoside, Lauryl glucoside) and polyglucosides (eg cellulose);

(8) mono-, di- and trialkyl phosphates and mono-, di- and / or tri-PEG-alkyl phosphates and their salts;

(9) wool wax alcohols;

(10) polysiloxane-polyalkyl-polyether copolymers or corresponding derivatives;

(11) mixed esters of pentaerythritol, fatty acids, citric acid and fatty alcohol according to DE-PS 1165574 and / or mixed esters of fatty acids with 6 to 22 carbon atoms, methyl glucose and polyols, preferably glycerol or polyglycerol and

(12) Polyalkylene glycols.

The adducts of ethylene oxide and / or of propylene oxide with fatty alcohols, fatty acids, alkylphenols, glycerol mono- and diesters and sorbitan mono- and diesters of fatty acids or with castor oil are known, commercially available products. These are mixtures of homologs, the middle of which Degree of alkoxylation corresponds to the ratio of the amounts of ethylene oxide and / or propylene oxide and substrate with which the addition reaction is carried out.

C _{8 /} i ₈ alkyl mono- and oligoglycosides, their preparation and their use are known from the prior art. They are produced in particular by reacting glucose or oligosaccharides with primary alcohols with 8 to 18 carbon atoms. Regarding the glycoside residue, both monoglycosides in which a cyclic sugar residue is glycosidically bonded to the fatty alcohol and oligomeric glycosides with a degree of oligomerization of up to preferably about 8 are suitable. The degree of oligomerization is a statistical mean value which is based on a homolog distribution customary for such technical products.

Typical examples of anionic emulsifiers are soaps, alkylbenzene sulfonates, alkane sulfonates, olefin sulfonates, alkyl ether sulfonates, glycerol ether sulfonates, α-methyl ester sulfonates, sulfo fatty acids, alkyl sulfates, alkyl ether sulfates such as, for example, fatty alcohol ether sulfates, glycerol ether sulfates, hydroxymate ether sulfates, hydroxymate ether sulfates, hydroxymate sulfate ethersulfates, fatty acid sulfate amide sulfates, hydroxymate ether sulfate, fatty acid sulfate amate sulfate, hydroxymate ether sulfate, fatty acid ether sulfate, fatty acid sulfate amate sulfate, hydroxymate ether sulfate, fatty acid ether sulfate, fatty acid sulfate amate sulfate, hydroxymate ether sulfate, fatty acid ether sulfate, hydroxymate ether sulfate, fatty acid sulfate amate sulfate, hydroxymate ether sulfate, fatty acid ether sulfate, fatty acid ether sulfate, hydroxymate ether sulfate, fatty acid ether sulfate, hydroxymate ether sulfate, hydroxymate ether sulfate, fatty acid ether sulfate, fate (f) - and dialkyl sulfosuccinates, mono- and Dialkylsulfo-succinamates, sulfotriglycerides, amide soaps, ether carboxylic acids and salts thereof, fatty acid taurides, N-acylamino acids such as acyl glutamates and acyl aspartates, alkyl oligoglucoside sulfates, protein fatty acid condensates (in particular vegetable products based on wheat), and alkyl (ether) phosphates. If the anionic surfactants contain polyglycol ether chains, they can have a conventional, but preferably a narrow, homolog distribution.

Zwitterionic surfactants can also be used as emulsifiers. Zwitterionic surfactants are surface-active compounds that contain at least one quaternary ammonium group and at least one carboxylate and one sulfonate group in the molecule. Particularly suitable zwitterionic surfactants are the so-called betaines such as the N-alkyl-N, N-dimethylammonium glycinate, for example the cocoalkyldimethylammonium glycinate, N-acylamino-propyl-N, N-dimethylammonium glycinate, for example the cocoacylamino propyldimethylammonium glycinate, and 2 -Alkyl-3-carboxylmethyl-3-hydroxyethylimidazolines each having 8 to 18 carbon atoms in the alkyl or acyl group and the cocoacylaminoethylhydroxyethylcarboxymethylglycinate. The fatty acid amide derivative known under the CTFA name of Cocamidopropyl Betaine is particularly preferred. Suitable emulsifiers are ampholytic surfactants. Ampholytic surfactants are surface-active compounds which, in addition to a Cs-alkyl or -acyl group, contain at least one free amino group and at least one -COOH or -SO ₃ H group in the molecule and are capable of forming internal salts. Examples of suitable ones Ampholytic surfactants are N-alkylglycines, N-alkylpropionic acids, N-alkylamino-butyric acids, N-alkyliminodipropionic acids, N-hydroxyethyl-N-alkylamidopropylglycines, N-alkyltaurines, N-alkylsarcosines, 2-alkylaminopropionic acids and alkylaminoacetic acids each with about 8 to 18 C atoms in the alkyl group. Particularly preferred ampholytic surfactants are the N-coconut alkyl aminopropionate, the coconut acylaminoethyl aminopropionate and the C _{2 /} i ₈ acyl sarcosine. In addition to the ampholytic emulsifiers, quaternary emulsifiers are also suitable, those of the esterquat type, preferably methyl-quaternized difatty acid triethanolamine ester salts, being particularly preferred.

Protective colloids suitable as surface modifiers are e.g. natural water-soluble polymers such as B. gelatin, casein, gum arabic, lysalbic acid, starch, albumin, alginic acid and their alkali and alkaline earth metal salts, water-soluble derivatives of water-insoluble polymeric natural substances such. B. cellulose ethers such as methyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose or modified carboxymethyl cellulose, hydroxyethyl starch or hydroxypropyl guar, and synthetic water-soluble polymers, such as. B. polyvinyl alcohol, polyvinyl pyrrolidone, polyalkylene glycols, polyaspartic acid and polyacrylates.

For the purposes of the invention, preference is given to surface modification agents which are selected from the group formed by the nonionic surfactants and mixtures thereof, addition products from 2 to 60 mol of ethylene oxide and castor oil and / or hardened castor oil, alkylmono- and oligoglycosides with 8 to 22 carbon atoms in the alkyl radical and polyalkylene glycols are to be understood.

The amount of surface modification agent with respect to the light protection filter corresponds at least to the amount that is required to provide a stable dispersion Obtain light protection filter nanoparticles. This minimum amount can be determined by simple routine tests.

As a rule, light protection filters and surface modification agents are used in a weight ratio of 1:10 to 10: 1 and preferably 1: 2 to 2: 1.

For the purposes of the invention, it is preferred if the average diameter of the light protection filter particles in the suspensions is in the range from 20 to 150 nm.

The size specifications are to be understood as the diameter in the direction of the greatest longitudinal expansion of the particles. When producing the finely divided particles, particles are always obtained with a size that follows a distribution curve. For example, the method of dynamic light scattering known to the person skilled in the art can be used for the experimental determination of the particle size.

In a further embodiment of the invention, the suspensions contain, in addition to at least one oil-soluble, at least one water-soluble light protection filter, the water-soluble light protection filter preferably being selected from the group formed by 2-phenylbenzimidazole-5-sulfonic acid and its alkali metal, alkaline earth metal, ammonium -, Alkylammonium, alkanolammonium and glucammonium salts, sulfonic acid derivatives of benzophenones, sulfonic acid derivatives of 3-benzylidene camphor and their mixtures.

It has been found that such light protection filter suspensions are particularly stable and, above all, particularly effective with regard to their UV-absorbing properties if at least some and particularly preferably the majority of the water-soluble light protection filters are part of the solid nanoparticulate particles are present. It is assumed that here molecules of the water-soluble light protection filter accumulate on the surface of the core from the oil-soluble light protection filters and, in the event that a surface modifier is additionally present in the suspension, the surface of the particles formed from the oil-soluble light protection filters partly by molecules of the surface modification agent and is partially surrounded by molecules of the water-soluble light protection filter. The high UV-absorbing effectiveness of such suspensions is attributed to a synergistic effect between the oil-soluble and the water-soluble light protection filters.

Depending on the ratio and nature of the oil-soluble or water-soluble light protection filters used in the manufacture of the suspensions and the surface modifiers that may be present, a more or less large part of the water-soluble light protection filters is built into the shell of the nanoparticles from the oil-soluble light protection filters, the rest remains in the aqueous phase the suspension.

In one embodiment of the invention, the majority of the water-soluble light protection filter is present in the suspension as a component of the solid nanoparticulate light protection filter particles.

In a particularly preferred embodiment of the invention, the suspension contains benzophenone-3 as an oil-soluble light protection filter and 2-phenylbenzimidazole-sulfonic acid or one of its salts as a water-soluble light protection filter.

The proportion of oil-soluble light protection filters is preferably 70 to 100% by weight, based on the total amount of light protection filters contained in the solid nanoparticles. The suspensions according to the invention contain 30 to 100% by weight and preferably 40 to 60% by weight of oil-soluble light protection filters, based on the total amount of the light protection filters contained in the suspensions.

The suspensions according to the invention and / or the nanoparticulate light protection filter particles contained in the suspensions according to the invention can be produced by different processes.

In the production by the evaporation process, the light protection filter is first in a suitable organic solvent, such as. B. an alkane, edible oil, alcohol, ether, ester, ketone or acetal dissolved. This solution is then added to a non-solvent for the light protection filter, preferably water, a lower alcohol or mixtures of several non-solvents, if appropriate in the presence of a surface modifier dissolved therein, in such a way that the organic solvent and non-solvent are mixed together Precipitation of the nanoparticulate light protection filter comes. This mixing is preferably carried out in a manner in which the organic solvent evaporates and is largely separated from the system. The solvent can also after mixing z. B. removed by distillation. Instead of the solution consisting of light protection filter and organic solvent, an O / W emulsion or O / W microemulsion can also be used, in which the oil component takes the place of the solution. The surface modification agents already explained at the beginning can be used as surface-active compounds.

Another possibility for producing the nanoparticulate particles is the so-called GAS process (Gas Anti Solvent Recrystallization). The GAS process uses a highly compressed gas or supercritical fluid (eg carbon dioxide) as a non-solvent for the crystallization of solutes. The condense The gaseous phase is introduced into the solution of the light protection filter in a suitable organic solvent, as described above, and absorbed there. The volume of liquid increases, the solubility of the light protection filter decreases and it is separated in the form of fine particles. The solvent is then removed before or after the addition of one or more non-solvents for the light protection filter, preferably water.

The PCA process (Precipitation with a Compressed Fluid Anti-Solvent) is also suitable. Here, the solution of the light protection filter in a suitable organic solvent, as described above, is injected into a supercritical fluid, such as carbon dioxide. This creates finely divided droplets in which diffusion processes take place, which lead to the precipitation of very fine particles. The solvent is then removed before or after the addition of one or more non-solvents for the light protection filter, preferably water.

In the PGSS process (Particles from Gas Saturated Solutions), the light protection filter is melted by injecting gas (e.g. carbon dioxide or propane). Pressure and temperature reach near or supercritical values. The gas phase dissolves in the solid and causes a lowering of the melting temperature, the viscosity and the surface tension. When expanding through a nozzle, cooling effects lead to the formation of fine particles, which are then dispersed in one or more non-solvents for the light protection filter, preferably water.

In the RESS process (Rapid expansion of supercritical Solutions), the light protection filter is placed in a pressure vessel, the reactor is closed and the supercritical solvent (CO ₂ , ethylene, propane, ammonia, methanol, N ₂ O, N ₂ O ₂ , SF ₆ , Difluoromethane, trifluoromethane, water, toluene, etc., but preferably CO ₂ ) pressed in while increasing the temperature until the desired supercritical Conditions are reached. A surface modification agent can also be submitted together with the light protection filter. After the light protection filter has been dissolved under supercritical conditions, possibly in the presence of the surface modifier, the solution is expanded through a nozzle, with the formation of nanoparticles. The expansion can take place in air, another gas or else into a liquid, for example water, which liquid in turn can contain a surface modifier in order to prevent undesirable caking of the particles.

In the grinding process, the light protection filter is comminuted by grinding, for example in a vibrating mill, bead mill or stirred ball mill, using grinding media with an average diameter below 200 μm. Possibly. the grinding is carried out in the presence of a surface modifier. The grinding process can be carried out dry or in one or more non-solvents for the light protection filter, preferably water. The grinding process can also be carried out with cooling.

In the melt-emulsification process, the light protection filter is placed in a liquid in which it is not soluble (non-solvent). Water or mixtures of water and non-aqueous polar solvents, such as, for example, ethanol, glycerol, ethylene glycol, propylene glycol or N-methylpyrrolidone, are suitable as non-solvents. The mixture is then heated above the melting point of the light protection filter to form a two-phase system. By adding one or more surface modifiers, the liquid phase of the molten light protection filter is emulsified in such a way that very fine droplets of the desired size are formed. Alternatively, the light protection filter and the non-solvent can be introduced together with the surface modification agent, melted and dispersed, or the melt of the light protection filter and surface modification agent can be mixed with the non-solvent. In yet another process variant, the melt of the light protection filter can be mixed with a solution of the surface modification agent in the non-solvent and dispersed. After the emulsion has formed, it is cooled below the melting point of the light protection filter, a nanoparticulate suspension being formed.

The type and amount of the surface modification agents and the intensity and duration of the mechanical energy to be introduced for the emulsification are to be selected so that the particles of the dispersion obtain the desired size. The respective parameters can be determined by simple routine tests.

In a preferred variant of the method, the light protection filter is melted together with the surface modification agent. Separately, the non-solvent is heated to a temperature above, preferably 5 to 10 ° C. above, the melting point of the light protection filter, preferably in the presence of a water-soluble light protection filter. The melt of light protection filter and surface modification agent is then combined with the non-solvent and dispersed by introducing mechanical energy and then cooled below the melting point of the dispersed light protection filter. It goes without saying that, instead of a light protection filter or surface modification agent, mixtures of several of these substances can also be used.

The suspensions of nanoparticulate light protection filter particles according to the invention are preferably produced by the melt-emulsifying method.

The light protection filter, together with the surface modification agent used, should be able to produce nanoparticles which are stably dispersible in water according to at least one of the production processes described above, wherein the average particle diameter of the nanoparticles is in the range from 10 to 500 nm. The usable combinations of light protection filters and surface modification agents can be selected by simple routine tests.

The production processes listed are only to be understood as examples and do not constitute any restriction.

The suspensions are preferably produced in such a way that the total amount of the light protection filters is 1 to 50 and particularly preferably 5 to 20% by weight, based on the total weight of the suspension.

The suspensions according to the invention are preferably used for the cosmetic treatment of the body, which is preferably a treatment of the skin and / or the hair, particularly preferably the skin, for protection against UV radiation.

In a further embodiment of the invention, the suspensions according to the invention are used to produce a preparation for the topical treatment of the skin and / or the hair.

Another object of the invention is thus a preparation for topical application to the body, comprising a suspension according to the invention as described above.

The cosmetic preparations according to the invention are preferably compositions for protecting human skin or hair against UV rays, preferably compositions for sun protection or make-up. The cosmetic preparation is preferably an aqueous or aqueous-alcoholic solution, an emulsion, a dispersion, a lotion, a milk, a gel, a cream, a wax / fat mass, a stick preparation, a spray or a foam aerosol.

Cosmetic preparations are furthermore to be understood as means for cleaning and / or caring for the body, in the sense of the invention in particular the skin or the hair, wherein, in addition to the preparation forms described above, hair shampoos, hair lotions, hair styling agents, hair setting agents, foam baths and shower baths are also suitable , In hair treatment products, the light-protecting effect is directed towards the hair and / or the scalp.

In addition to the suspension of the light protection filter according to the invention, the cosmetic preparations additionally comprise a physiologically compatible carrier.

The physiologically acceptable carrier comprises one or more adjuvants, such as are commonly used in such preparations, such as. B. thickeners, moisturizing and / or moisturizing substances, surfactants, emulsifiers, plasticizers, anti-foaming agents, fats, oils, waxes, silicones, sequestering agents, anionic, cationic, nonionic or amphoteric polymers, alkalizing or acidifying agents, alcohols, polyols , Softeners, adsorbents, electrolytes, blowing agents, organic solvents, preservatives, bactericides, antioxidants, fragrances, flavors, sweeteners, dyes, pigments and light stabilizers. Light stabilizers are understood to mean substances which absorb or reflect UV radiation. The former are also known under the name of light protection factors, light protection filters or UV filters and generally provide organic or liquid organic or liquid at room temperature Substances, while the latter include in particular the light protection pigments.

The cosmetic preparations according to the invention contain the suspension according to the invention of the solid particles of the light protection filter in such an amount that the total concentration of the light protection filters in the preparation is between 0.5 and 20% by weight, preferably between 5 and 15% by weight, based on the Total weight of the preparation.

On the one hand, the suspensions according to the invention can be produced economically and, on the other hand, show both good incorporability and stability in preparations and high UV-absorbing activity.

The nanoparticles contained in the dispersions according to the invention have a very large surface area, based on the amount of light protection filter used, so that UV absorption is particularly effective. When used in the form of the preparations according to the invention, the nanoparticles are deposited on the skin or hair due to their small particle size in such a way that they cover the surface in a very thin layer which on the one hand can efficiently absorb UV radiation and on the other hand through mechanical impacts are not easily removable. Since the nanoparticulate particles also agglomerate when the carrier evaporates or is drawn in, a film that adheres very well to the skin and is particularly waterproof is created.

The suspensions according to the invention can be used, for example, in purely aqueous preparations and also in emulsions. With the latter there is the possibility of an oil-soluble light protection filter in the oil phase, and a suspension of an oil-soluble light protection filter, optionally in combination with a water-soluble light protection filter, in the water phase to achieve a particularly high UV protection. It is understood that a plurality of different light protection filters can always be used in each case.

The following examples are intended to illustrate the present invention.

Examples

Example 1: Preparation of a nanoparticulate suspension of Benzophenone-3

5.0 g Neo Heliopan BB (Benzophenone-3) were mixed with 5.0 g Eumulgin HRE 455 (hardened castor oil with 40 mol ethylene oxide in propylene glycol / water) and 5.0 g Eumulgin RO 40 (castor oil with 35 to 40 mol ethylene oxide) melted at approx. 80 ° C. This melt was slowly dropped into 85.0 g of water at 65 ° C, stirred for about 5 minutes, and then cooled with a water bath at 20 ° C. A stable opaque suspension was obtained. In the light scattering, the suspended particles showed a maximum with a particle size of 80 nm with volumetric weighting.

Example 2: Preparation of a nanoparticulate suspension of benzophenone-3 and 2-phenylbenzimidazole sulfonic acid

8.0 g Neo Heliopan BB (Benzophenone-3) were melted with 10.0 g Eumulgin RO 40 at approx. 70 ° C. 12.0 g of Neo Heliopan Hydra (2-phenylbenzimidazole sulfonic acid) were added to 70.0 g of water and adjusted to a pH of 7.5 with sodium hydroxide. The solution formed was then heated to 65 ° C. The melt was slowly dropped into the aqueous solution, stirred for about 5 minutes, and then slowly cooled with a water bath at 20 ° C. In the light scattering, the particles of the suspension formed in this way showed a maximum with a particle size of 130 nm with volumetric weighting.

(3.1) W / O sun protection cream, (3.2-3.4) W / O sun protection lotion, (3.5, 3.8, 3.10)

O / W sun protection lotion

(3.6, 3.7, 3.9) O / W sun protection cream

Claims

claims

1. Aqueous suspension of solid particles of light protection filters, the particles having an average diameter in the range from 10 to 500 nm and containing at least one light protection filter and preferably at least one surface modification agent.

2. Suspension according to claim 1, characterized in that the light protection filters are oil-soluble.

3. Suspension according to claim 1 or 2, characterized in that the light protection filter is selected from the group formed by 3-benzylidene camphor or 3-benzylidene norcampher and its derivatives, 4-aminobenzoic acid derivatives, cinnamic acid esters, salicylic acid esters, benzalmalonic acid esters , Benzophenone derivatives, benzoylmethane derivatives, triazine derivatives, propane-1, 3-diones, ketotricyclo (5.2.1.0) decane derivatives and mixtures thereof.

4. Suspension according to one of claims 1 to 3, characterized in that the surface modification agents are selected from the group formed by the nonionic surfactants and mixtures thereof.

5. Suspension according to one of claims 1 to 4, characterized in that the average diameter of the light protection filter particles is in the range from 20 to 150 nm.

6. Suspension according to one of claims 1 to 5, characterized in that the light protection filters are present in a concentration between 1 and 50 and preferably between 5 and 20 wt .-% based on the total weight of the suspension.

7. Suspension according to one of claims 1 to 6, characterized in that it contains at least one oil-soluble and at least one water-soluble light protection filter.

8. Suspension according to claim 7, characterized in that the water-soluble light protection filter is selected from the group formed by 2-phenyl benzimidazole-5-sulfonic acid and its alkali, alkaline earth, ammonium, alkylammonium, alkanolammonium and glucammonium salts, sulfonic acid derivatives of benzophenones, sulfonic acid derivatives of 3-benzylidene camphor and their mixtures.

9. Suspension according to one of claims 7 or 8, characterized in that at least part of the water-soluble light protection filter is present as a component of the solid nanoparticulate light protection filter particles.

10. Suspension according to claim 9, characterized in that the predominant part of the water-soluble light protection filter is present as a component of the solid nanoparticulate light protection filter particles.

11. Suspension according to one of claims 7 to 10, characterized in that benzophenone-3 is contained as an oil-soluble light protection filter and 2-phenylbenzimidazole-sulfonic acid or one of its salts is contained as a water-soluble light protection filter.

12. A method for producing a suspension according to any one of claims 1 to 11 with the steps

(a) melting one or more light protection filters in the presence of an effective amount of one or more surface modifiers

(b) dispersing the melt in a liquid in which the molten light protection filters are insoluble

(c) cooling the dispersion below the melting point of the dispersed light protection filter.

13. The method according to claim 12, characterized in that in sub-step (b) at least one water-soluble light protection filter is dissolved in the liquid.

14. Use of a suspension according to one of claims 1 to 11 for the cosmetic treatment of the body.

15. Use according to claim 14, characterized in that it is a treatment of the skin and / or hair to protect against UV radiation.

16. Use of a suspension according to one of claims 1 to 11 for the manufacture of a preparation for the topical treatment of the skin and / or hair.

17. A preparation for topical application to the body, comprising a suspension according to any one of claims 1 to 11.

18. Preparation according to claim 17, characterized in that it is a sunscreen.

19. Preparation according to one of claims 17 or 18, characterized in that it contains the suspension of the solid particles in such an amount that the total concentration of the light protection filter in the preparation between 0.5 and 20 wt .-% and preferably between 5 and 15 wt .-%, based on the total weight of the preparation.