MXPA00004515A - Photostable cosmetic light screening compositions - Google Patents

Abstract

The invention relates to a photostable cosmetic or pharmaceutical light screening composition containing a dibenzoyl methane UV-A screening agent and a p-methoxycinnamate UV-B screening agent, one of said agents being incorporated into a polymer latex;and, optionally, other conventional UV-A and UV-B screening agents. Furthermore the invention relates to a method of photostabilizing dibenzoyl methane UV-A screening agents and p-methoxycinnamate UV-B screening agents when used together, by incorporating one of these agents into polymer latex.

Description

COSMETIC COMPOSITIONS FOR FI LIGHTING, PHOTOESTABLES Field of the Invention The invention relates to light screening, cosmetic, pharmaceutical and photographic compositions for the protection of the human epidermis or hair against ultraviolet rays of wavelengths comprised between 280 and 400 nm (UV-A / UV-B). ).

More specifically, the invention relates to photostable light screening compositions, which contain a UV-A screening agent of dibenzoyl methane and a UV-B screening agent of p-me t oxycinnamate or, in which one of the screening agents is incorporated in a polymeric matrix.

Background of the Invention U.S. Patent No. 5,372,804 (Chesebrough-Pond's) refers to cosmetic compositions comprising at least one agent of Ref: 119724 shielding of light, in which the light screening agent is transported inside or on polymeric latex particles. The polymeric latex particles achieve a good deposition of the light screening agents on the hair or on the skin. Specifically, light screening agents have been disclosed which include benzophenone compounds, dibenzoyl methane derivatives and cinnamate derivatives such as 2-ethexhexyl-p-methoxycinnamate (PARSOLTMCX). The polymer particles used can be of any polymeric material that is a good film former. The polymer particles can be substantially solid or can be porous and have a particle size of between 10-1000 nm. In order to obtain polymers having characteristics of film formers, it is necessary that they present a low glass transition temperature in the usual temperature range of the cosmetic composition, approximately 30 ° C.

The aforementioned US patent only shows that the light screening agents can be incorporated into a matrix, thus achieving greater deposition. Said US Patent does not focus on the problem of photo-stability, which occurs due to an interaction of 4-tert-but-il-4 '-metoxidibenzoi-1 methane (PARSOL®! 89) with other light screening agents in light conditions, especially with 2-ethylhexyl-p-me t oxycinnamate or (PARSOL®MCX).

Cosmetic light screening compositions based on dibenzoyl methane derivatives as a UV-A screening agent and tainted photographs with 3, 3-phenylalkyl derivatives are described in the European Patent Publication. EP-0 514 491 Bl and in European Publication EP 0 780 119 Al. However, this type of abilization does not prevent photochemical interaction between cyanamate derivatives, such as 2-ethyhexyl-p-me toxicinamate and dibenzoyl derivatives methane, such as 4-tert-butyl-4'-methoxy-dibenzoyl methane.

Description of the invention It has now been discovered that the photostability of light screening compositions containing a dibenzoyl methane UV-A screening agent and a lightning shielding agent UV-B, its one of said light screening agents is incorporated into a polymeric latex.

Accordingly, one aspect of the invention relates to a photoimage method of blends of a UV-A ray shielding agent of dibenzoylmethane and a UV-B screening agent of p-methoxycinnamate in a screening composition. of light, wherein said method comprises the incorporation of one of said light screening agents in a polymeric latex.

Another aspect of the invention relates to a light screening composition containing, based on the total weight of the composition, between 0.5% by weight and 5% by weight of a UV-ray shielding agent. A of dibenzoyl methane incorporated in a polymeric latex, between 1% by weight and 15% by weight of a UV-B screening agent of p-methoxycinnamate; and optionally other conventional UV-A- and UV-B screening agents.

Another aspect of the invention relates to a light screening composition which contains, based on the total weight of the composition, between 1% by weight and 15% by weight of a UV-B screening agent for the light. -met oxycinnamate incorporated in a polymeric latex, between 0.5% by weight and 5% by weight of a dibenzoyl methane UV-A screening agent; and optionally conventional UV-A and UV-B screening agents.

As to the dibenzoyl methane UV-A screening agent, the preferred compound is 4-1 erc-but i 1-4 '-metoxidibenzoyl methane sold under the tradename PARSOLT1789.

Other suitable compounds belonging to this particular type are: 2-methyldibenzoi-1-methane, 4-met-il-dibenzoyl-methane, 4-isopropyldibenzoi-1 methane, 4-tert-butyldibenzoyl-methane, 2,4-dimethyldibenzoyl-methane, , 5-dimethyldibenzoi-1-methane, 4,4'-di-isopropyldibenzoyl-methane, 2-methyl-5-isopropyl-1-methoxy-benzoyl-methane, 2-methyl-5-tert-butyl-1-methoxy-dibenzoyl-methane, 2,4 -dime t ail-4 '-met oxidibenzoyl methane and 2,6-dimethyl-tert-but i 1-' -methoxydibenzoyl methane.

As used herein, the term "UV-B-screening agent" for p-methoxycinnama to refers to derivatives such as 2-ethoxyethyl-p-me t-oxycinnamate or, 2-ethylhexyl (or pentyl) p- toxicinama to, potassium-p-methoxycinnamate, sodium-p-met oxycinnamate, ammonium-p-methoxycinnamate, salts of primary, secondary or tertiary amines of p-methoxycinnamic acid with mono-, di-, tri- ethanol amine and the like. Preferred is 2-ethylhexyl-p-methoxycinamine sold under the tradename PARSOL® MCX.

As used herein, the term "polymeric latex" refers to a stable colloidal dispersion of polymer particles in an aqueous or substantially aqueous phase, including polymers and / or copolymers of uni-functional monomers and / or multifunctional monomers. The UV-A screening agent of dibenzoyl methane or the UV-B screening agent of p-met oxycinnamate is incorporated into the polymer matrix.

As used herein, the term "unifunctional monomers" includes Ci-Ca-alky1 (meth) acrylic, such as 2 -et i 1 -hexy lacrylate, C 1 -C 8 -alkyl (me t) acrylic acid, acrylic acid , styrene, ethylene, propylene, butylene, butadiene, isopropene, isobornylmethacrylate (IBOMA), trifluoroethyl methacrylate, perfluoroa, l, l-ethyl acrylate, and the like.

As used herein, the term "multifunctional monomers" includes 1-methyl acrylate (ALMA), ethylene glycol dimethacrylate (EDGMA), and the like.

A preferred polymeric latex is a stable colloidal dispersion of copolymer particles of methyl methacrylate (MMA) and acrylic acid (AA) crosslinked with allylmethacrylate (ALMA) and ethylene glycol dimethacrylate (EDGMA) or isobornyl methacrylate (IBOMA) crosslinked with allylmethacrylate (ALMA).

The polymer particles may have a matrix structure within which the dibenzoyl methane UV-A screening agent or the p-me toxicinamate UV-B screening agent is homogeneously distributed over the total volume of the polymer particles, or the polymer particles can have a deposit structure.

As used herein, the term "reservoir structure" refers to particles having a polymeric core surrounded by a polymeric shell, wherein the core contains the dibenzoyl methane UV-A screening agent or the biodegradable agent. shielding of UV-B rays from p-met oxycinnama to.

In one aspect, the core and shell portions of the core / shell polymer particles may have the same chemical composition with respect to the monomers used. Uni functional and multifunctional monomers such as those listed above.

In another aspect, the core and shell portions of the core / shell polymer particles may differ in their chemical composition. In this case, the monomers used in the core portion of the core / shell particles may also include the unifunctional and multifunctional monomers listed above. The monomers used in the cover portion of the core / shell particles suitably include hydrophilic or fluorinated roonomers.

Preferred core / shell particles include particles in which a) the core consists of a polymer and / or copolymer of methyl methacrylate (MMA) and acrylic acid (AA) crosslinked with allyl methacrylate - (ALMA) and ethylene glycol dimethacrylate (EGDMA) or. it is composed of isobornylmethacrylate lat (IBOMA) cross-linked with allylmethacrylate (ALMA); and b) the cover consists of a hydrophilic polymer or fluorinated polymer chains.

The hydrophilic polymeric covers are obtained by copolymerization of monomers containing carboxylic acid groups such as acrylic acid, methacrylic acid, monomers having hydroxyl groups such as for example hydroxy C6-alkyl (meth) acrylate, (HEMA) and acrylamides (AAm). A hydroxy C? - C ß ~ alkyl 1 (me t) suitable acrylate is hydroxyethyl methacrylate.

The fluorinated polymer coatings are obtained by copolymerization of acrylic esters, such as for example methyl methacrylate (MMA) or isobornylmethacrylate lat (IBOMA) with fluorinated monomers such as for example trifluoroethylmethacrylate (TRIFEMA) or perfluoroalkyl-2-ethacrylate (PF2EA). ).

The core may be surrounded by a cover or by two or more covers, whereby the first cover that surrouthe core and the next cover may be formed by the same polymer or by different polymers. For example, the first cover can be formed by a hydrophilic polymer and the next cover can be formed by a fluorinated polymer and vice versa.

If the core and shell are not formed by the same polymer particles, a two-component core-shell polymer with several morphological structures is obtained, as described in Chen et al., Macrolecules 1991, 24, 3779-3787.

The polymer particles, as defined above, have a glass transition temperature between about 50 ° C and 100 ° C. The glass transition temperature can be adjusted to a given value by choosing the initial content of each monomer and by crosslinking with the above mentioned multifunctional monomers.

Generally, a high content of crosslinking agent increases the glass transition temperature, while high lengths of the alkyl chain in acrylate monomers decrease the glass transition temperatures of the polymer latex. In addition, the glass transition temperature of the polymer latex can be decreased by increasing the levels of the incorporated screening agent, for example PARSOL® 1789.

The glass transition temperature of the polymer used for the core portion may be the same as or different from the glass transition temperature of the polymer used for the shell portion.

Polymeric latex containing polymeric particles having the UV-A screening agent of dibenzoyl methane or the UV-B screening agent of p-me toxicinama to be incorporated in the matrix, can be produced by the polymerization of the emulsion, including a crosslinking process, thus, polymer particles having a glass transition temperature > 50 ° C, preferably > 70 ° C.

The transition temperature of the glass is an important parameter, since the polymer particles must be in a crystalline state at the conservation temperature, in order to offer a high stability and solidity to the system.

The preparation of latex polymer by polymerization of the emulsion is well known. For example, U.S. Patent No. 5,189,107 discloses that latex polymers with a uniform particle size can be obtained by the use of latex beads in the polymerization reaction to better control the particle size distribution.

Thus, the invention also comprises a process for the preparation of polymeric particles having a matrix structure within which, a dibenzoyl methane UV-A screening agent or a UV-B screening agent for p -metoxycinnamate is distributed homogeneously throughout the volume of the particles and said process comprises a) dissolution of the UV-A screening agent of dibenzoyl methane or the apan agent such a UV-B light of p-met oxycinnamate or in a monomer mixture; b) pre-emulsification of the solution from step a) in an aqueous solution containing an emulsifier; cl) introduction. continuously from the preemulsion of step b) in a reactor containing an aqueous solution or c2) introducing a small amount of the preemulsion from step b) into a reactor containing an aqueous initiator solution, thereby obtaining polymer particles and subsequently the introduction of the remaining pre-emulsion.

The temperature in the reactor of step cl or c2 is between 70 ° C and 90 ° C, preferably 80 ° C.

The latex obtained by the polymerization process of the emulsion described above consists of a colloidal dispersion of polymer particles having a matrix structure, inside which a dibenzoyl methane UV-A screening agent or a screening agent of UV-B rays of p-methoxycinnama to is distributed homogeneously throughout the volume of the particles.

The latex containing polymer particles having a deposit structure can be prepared by a two step polymerization process of the emulsion, comprising a first polymerization step to obtain the polymer particles of the core and a second polymerization step to obtain particles polymers having at least one layer surrounding the core.

The first polymerization step can be carried out as described above in steps a), b), cl) and C2).

The second step of the polymerization comprises another polymerization of the emulsion, which is carried out according to steps b), cl) and c2) in the presence of the latex prepared in the first polymerization step and in the absence of screening agents of light, using the same or different monomers used in the first step.

In an embodiment of the invention, the second polymerization step comprises the addition of monomer containing carboxylic acid groups, such as acrylic acid (AA), methacrylic acid (MAA), monomers having hydroxyl groups such as for example hydroxy C- β-alkyl (meth) acrylate, (HEMA) and acrylamides (AMD).

In another embodiment of the invention, the second polymerization step comprises the addition of monomers containing acrylic esters such as for example methyl methacrylate (MMA) or isobornylmetacrilate (IBOMA) and fluorinated monomers such as for example trifluoroethyl methacrylate (TRIFEMA) or perf luoroa lqui 1 -2 -eti lacrila to (PF2EA).

The core / shell particles of the present invention can also be prepared by an inverted core / shell polymerization process, in which the shell portion is first prepared, followed by the polymerization of the core monomer in the presence of shell materials. the cover.

The appropriate weight ratio of the portion of the core to the portion of the shell is between 1 and 10.

Suitable emulsifiers are anionic and nonionic surfactants, preferably anionic surfactants.

Conventional anionic surfactants which can be used are for example alkyl sulfate, alkyl ether sulfates, alkyl succinates, alkyl sulfosuccinates, alkyl phosphates, alkyl ether phosphates, alkyl ether carboxylates, especially their sodium, magnesium, ammonium and mono-, di- -, and triethanolamine, the alkyl groups generally contain between 8 and 18 carbon atoms and can be unsaturated.

Suitable anionic surfactants are sorbitan derivatives marketed under the trade name TWEEN by ICI Americas Incorporated, Wilmington. Preferred are polyoxyethylene glycoside fatty acid esters such as, for example, polyoxyethylene (20) sorbitan monolaurate, which is marketed under the tradename TWEEN 20 (ICI Chemicals).

Other suitable and preferred surfactants are ABEX®3594 (Rhone-Poulenc) or DOWFAX® 8390 (Dow Chemical).

As used herein, the term "initiator solution" refers to an aqueous solution of peroxides, perfosphates, percarbonates, persulfates, organic peroxides and salts thereof. The preferred one is ammonium persulfate.

The polymer particles have a particle size of between 100 nm and 500 nm, preferably between 100 nm and 400 nm, more preferably between 250 nm and 350 nm.

When convenient, the light screening composition of the present invention may also include other conventional UV-A and UV-B screening agents.

The term "conventional UV-B screening agents", ie substances having a maximum absorption between 290 and 320 nm, refers to the following UV-B screening agents: Acrylates such as 2-ethylhexyl 2-cyano-3, 3-diphenylacrylate (oct ochylene, PARSOL® 340), ethyl 2-cyano-3,3-diphenylacrylate and the like; Camphor derivatives such as methyl benzylidene camphor PARSOL® 500), 3-benzylidene camphor, camphor benzalkonium methosulfate, polyacrylamidomethyl benzylidene camphor, sulfo benzylidene camphor, sulfomethyl benzylidene camphor, terephthalidene dialkanol sulfonic acid and the like; Organosiloxane compounds containing the banezomalonate group as described in European Patent Publications PE 0358584 Bl, PE 0538431 Bl and European Publications PE 0709080 Al and PE 0897716 A2.

Pigments such as microparticulate Ti02 and the like. The term "microparticulate" refers to a particle size of between 5 nm and about 200 nm, particularly between 15 n and about 100 nm. The Ti02 particles can also be coated with metal oxides such as for example aluminum or zirconium oxides or with organic coatings such as for example polyols, methicone, aluminum stearate, alkyl silane. Said coatings are well known in the field.

Imidazole derivatives such as, for example, 2-phenylbenzylidene sulfonic acid and its salts (PARSOL® HS). Salts of 2-phenylbenzyl imide sulfonic acid are for example alkali metal salts such as sodium or potassium salts, ammonium salts, morpholine salts, salts of primary, secondary and tertiary amines such as monoethanolamine salts, diethanolamine salts and imi lares.

- Salicylate derivatives such as i sopropi lbenzyl salicylate, benzyl salicylate, butyl salicylate, octyl salicylate (NEO HELIOPAN OS), isooctyl salicylate or homomentil salicylate (homosalate, HELIOPAN) and the like; - Triazone derivatives such as octyl triazone (UVINUL T-150), dioctyl butamido triazone (UVASORB HEB) and the like; The term "conventional UV-A screening agents", ie substances that exhibit their maximum absorption between 320 and 400 nm, refers to the following UV-A screening agents; - Derivatives of dibenzoyl methane such as 4-tert-butyl-1-methyl t-oxidinenzoyl-methane (PARSOL® 1789), dimethyl oxydibenzoi-1-methane, isopropyldibenzoyl-methane and the like; - Benzotriazole derivatives such as 2 2'-methylene-bis (6-. {2H-benzotriazol-2-yl) -4- (1, 1,3,3-tetramethylbutyl) -phenol (TINOSORB M) and the like; Triazine derivatives such as 2,2 '- [6- (4-methoxyphenyl) -1,3,5-triazine-2,4-diyl] bis [5- [2-ethylhexyl) oxy] -; available under the trade name of TINOSORB S from Ciba Specialty Chemicals Holding Switzerland.

Pigments such as microparticulate ZnO and the like. The term "microparticulate" refers to a particle size of between 5 nm and about 200 nm, particularly between 15 nm and about 100 nm. The ZnO particles can be coated with oxides of metals such as for example aluminum or zirconium oxides or with organic coatings such as for example polyols, methicone, aluminum stearate, alkyl silane. Said coatings are well known in the field.

Suitable organosiloxane compounds are those which have been described in European Patent PE 0538431 Bl, called compounds of the general formula I, where R means Ci_6 alkyl or phenyl; A means a group of the formula lia and / or Ilb; Ilb where R1 and R2 each independently means hydrogen, hydroxy, Cj-e-alkyl or Ci-s-alkoxy; R3 is Ci-e-alkyl; R4 means hydrogen or C-i-s-alkyl; R5 and R6 each independently means hydrogen or C6-alkyl; r has a value between 0 and 250; s has a value between 1 and 20; have a value of at least 3 n has a value between 1 and 6; The term "Ci-e-a lqui lo" refers to groups such as methylopropyl, isopropyl, butyl, sec. utilo, isobutyl, pentyl and neopentyl.

The term "C? -6-a-1-coxyl" refers to the corresponding alkoxy groups.

The residues R are preferably methyl.

The residues R1 and R2 are preferably hydrogen, methoxy or ethoxy, more preferably hydrogen, or one of R1 and R2 is hydrogen and the other is methoxy or ethoxy.

The R3 residues are preferably methyl or ethyl, more preferably ethyl.

Preferably, R4 is hydrogen or methyl, Rs and R are hydrogen and n is 1 Among the organs and loxanes described above, the following organs and loxane compound of the general formula I described in European Patent Publication PE 0709080 A1 and hereinafter referred to as "Polysiloxane A" is preferred. The Polysiloxane A is a compound of the above formula I, wherein R means methyl; A means a group of the formula Ilaa and / or Ilbb; r is a statistical measure of about 4; s is a statistical measure of around 60 In case A means a group of the formula (lia or Ilb) or of the formula (Ilaa and Ilbb) respectively, the ratio of polysiloxane units having a chromophore residue A of the formula lia or Ilaa respectively, with respect to those that present a chromophore residue A of the formula Ilb or Ilbb respectively, is not critical.

Other suitable organosiloxane compounds are those described in European Patent EP 0358584 Bl, called for example compounds of the general formula I wherein R means methyl; A means a group of the formula lie where R - R and n are as described above The preparation of novel light screening compositions, especially of preparations for the protection of the skin and, respectively, sun protection preparations for common cosmetics as well known to those skilled in the art and comprises the incorporation of polymeric latex containing UV-A screening agent for dibenzoyl methane or the UV-B screening agent for p-met oxycinnamate or optionally together with other conventional UV-B screening agents and / or screening agents UV-A conventions as described above, on a cosmetic basis that is customary for light protection agents.

In a cosmetic composition of the invention, the polymeric latex particles act as a vehicle for the dibinzoyl methane UV-A screening agent or the UV-B screening agent for p-methoxycinnamate.

The solid content of the polymer particles in the latex which is suitable is between 10% by weight and about 50% by weight.

The latex contains the dibenzoyl methane UV-A screening agent in an amount between 5% by weight and about 30% by weight, preferably between 5% by weight and about 15% by weight, more preferably between 6% by weight and about 10% by weight or the latex contains the UV-B screening agent of p-me t oxycinnamate or in an amount of between 15 weight and about 15% by weight, preferably between 2% by weight and about 8% by weight, more preferably around 5% by weight.

The amount of conventional UV-B screening agents and / or conventional UV-A screening agents is not critical. The adequate amounts are for example Polysiloxane A 'between 0.5 and about by weight, PARSOL® 340 between 0.5 and about 10% by weight, PARSOL® 5000 between 0.5 and about 4% by weight, PARSOL1- HS between 0.5 and about 10% by weight, TINOSORB M. • between 0.5 and about 10% by weight, Ti02 between 0.5 and about 25% by weight, ZnO between 0.5 and around of 20% by weight.

The light screening compositions of the present invention can be used as pharmaceutical or cosmetic formulations. The term "cosmetic" as used herein denotes topical formulations whose objective is the maintenance, improvement or restoration of the skin and hair. The term "pharmaceutical" used herein denotes topical formulations which are intended for therapy and disease prophylaxis and include formulations containing active ingredients that exert a medicinal effect.

The compositions of this invention conveniently adopt form of lotion, gel, solid stick, emulsion, for example cream, milk or vesicular dispersion, ionic or nonionic amphiphilic lipids, aerosol, dew, foam, powder , of shampoo, of hair conditioner, of lacquer or of make-up, etc., see also, Sunscreens, Development, Evaluation and Regulatory Aspects, ed. NY. Lowe, N.A. Shaath, Marcel Dekker, Inc. New York and Basel, 1990.

Customary excipients and auxiliary agents known to those skilled in the art can be used for the preparation of these forms, for example oils, waxes, alcohols, polyols, etc., particularly fatty acids, esters, fatty alcohols, and also ethanol, isopropanol, propylene glycol, glycerin , etc.

The formulations may contain other adjuvants, for example, other solvents, thickeners, emollients, emulsifiers, humectants, surfactants, preservatives, defoamers, fragrances, oils, waxes, lower polyols and monohydric alcohols, propellants, silicones, dyes and pigments, etc.

For hair protection, suitable shampoos are shampoos, conditioners, lotions, gels, emulsions, dispersions, lacquers, etc.

The preparation of all these formulations is well known to those skilled in the art.

The following examples explain the invention in more detail, but do not thereby limit its scope in any way.

Example 1 Determination of the transition temperature of the crystal.

The polymer film was prepared from the latex. The latex was dried and evaporation of the water allowed to obtain the coalescence of the charged polymer particles and the formation of a cracked film. The glass transition temperature was measured by Differential Scanning Calorimetry (DSC) performed with a DSC Mettier TC11 equipment. Samples of the film were examined in sealed aluminum containers in the temperature range 30 ° C / 130 ° C, a heating rate of 10 ° C / min.

Example 2 Determination of the particle load The amount of dibenzoyl methane (charge) UV-A screening agent incorporated in the polymer particles was determined as described below: The measurement of the PARSOL® 1789 content within the particles (particle loading) was performed by a UV spectrometer working at a wavelength of 357 nm. A known amount of polymeric film was introduced into a vessel containing tetrahydrofuran (THF). This solvent swelled the latex microparticles and solubilized the encapsulated PARASOL '1789. The absorption of PARSOL® 1789 was measured and compared with reference solution samples (calibration curve) to determine the current PARASOL® content in the polymeric film. The rate of incorporation is defined as the ratio of the weight of PARASOL® 1789 incorporated in the polymer particles (measured by the UV technique) in relation to the weight of the polymer. The encapsulation yield is defined as the weight ratio of PARASOL® 1789 incorporated in the polymeric particles (measured by the UV technique) in relation to the total weight of PARASOL® 1789 introduced.

Example 3 Determination of the photo tabili zant effect e.

The photo-stabilizing effect was measured by the method described below. The amount of latex needed to obtain the equivalent of 1% by weight of PARSOL® 1789 from the solid content and charged PARASOL® 1789 was calculated, 2% by weight of PARASOL® MCX, 30% of TWEEN 20 was added and finally, up to 100% by weight with distilled water was completed. mg of the above-prepared solution was dispersed on a glass plate (10 cm 2). After a drying time of 30 minutes, three identical samples were irradiated with 10 MED. Subsequently the samples were immersed in THF and left with ultrasound for 15 minutes. The THF of the three samples together evaporated and 2 ml of methanol was added to the evaporated. Finally the sample was filtered and analyzed by HPLC.

Example 4 Preparation of a latex containing EGDMA Step a) PARSOL® 1789 Solution A solution of 58.9 g of PARSOL® 1789 was prepared in the mre of the following monomers: • 303.9 g of MMA, 9.4 g of AA, 4.7 g of ALMA, 15.7 g of EGDMA.

Step b) Pre-emulsion In a polyethylene container, 120.1 g of demineralized water was mixed with 5.9 g of an aqueous solution of ABEX® 3594 surfactant (36% solid content) under gentle agitation. the PARSOL® 1789 solution of step a) was continuously added to the aqueous mre under stirring (8000 rpm) for 30 minutes.

Step c2) Polymerization 3% by weight of the pre-emulsion and an ammonium persulfate solution were added in a reactor containing water and heated to 80 ° C. After 15 minutes, the remaining pre-emulsion was added continuously for 3 hours and 30 minutes at 80 ° C. Then the latex was cured at 80 ° C for 120 minutes. The reactor temperature was lowered to 60 ° C and a redox system (tere.butyl hydroperoxide / Na2S205) was added to the reactor to remove residual monomers. The temperature was maintained at 60 ° C for 30 minutes. Finally, the latex was cooled to room temperature, filtered through a 50 μm sieve and neutralized to pH 7.3 with 20% by weight NaOH. The solid content of latex was 46.1% by weight. The particle size of the polymer particles in the latex was approximately 260 nm. The glass transition temperature was 83.5 ° C.

The content of PARSOL® 17: was 12, 9¡ in > that in the solid part of the latex and 6% in weight in the latex.

Example 5 Preparation of latex containing IBOMA.

Step a) PARSOL® 1789 Solution A solution of 58.9 g of PARSOL® 1789 was prepared with the mre of the following monomers: 249.5 g of MMA, 9.7 g of AA, 9.7 g of ALMA, 64.8 g of IBOMA, Step b) Pre-emulsion In a polyethylene vessel, 132.8 g of demineralized water were mixed with 5.9 g of aqueous solution of ABEX® 3594 surfactant (36% solid content under gentle stirring, the PARASOL® 1789 solution from step a) was added continuously to the aqueous mre under stirring (8000 rpm) for 30 minutes.

Step c2) Polymerization 3% by weight of the pre-emulsion and the initiator solution was charged to the reactor containing water and heated to 80 ° C. After 15 minutes, the remaining preemulsion was added continuously for 3 hours and 30 minutes at 80 ° C. Then the latex was cured at 80 ° C for 120 minutes. the reactor temperature was lowered to 60 ° C and a redox system (tere.butyl hydroperoxide / Na2S205) was added to the reactor to remove residual monomers. The temperature was maintained at 60 ° C for 30 minutes. Finally, the latex was cooled to room temperature, filtered through a 50 μm sieve and neutralized to pH 7.3 with 20% by weight NaOH. The solid content of the latex was 45.2% by weight. The particle size of the polymer particles of the latex was around 303 nm. The glass transition temperature was 90.0 ° C.

The content of PARSOL® 1789 was 13.3% by weight in the solid part of the latex and 6% by weight in the latex.

Example 6 In an analogous manner to Example 4, the compositions of the modified polymer matrices were prepared including functional hydrophilic monomers in the polymerization step. The compositions and results are shown in Table I below: Table I Example 7 In a manner analogous to the process of Example 4, but adding a hydrophilic monomer (methacrylic or acrylic acid) after the introduction of 80% of the pre-emulsion, the compositions were prepared as indicated in Table II: Table II Example 8 The core-shell nanoparticles were prepared by a two step emulsion polymerization process, a nanoparticle dispersion (prepared analogously to Example 4 using DOWFAX 8390 as a surface active agent in the pre-emulsion) was used as the initial point to polymerize a polymeric shell around the core particles, for the purpose of producing a polymeric membrane free of screening agent and including hydrophilic monomers. Various mres of monomers were used as summarized in Table III below: Table III The process of the polymerization of the shell is carried out as described without dilution of the latex balls. However, it added the same amount of water as the monomers used in the preparation of the polymeric shell to the polymerization reaction to form the shell. Therefore, the latex bags and the latex core shell latex show the same solid content. The compositions and the results obtained are shown in Table IV: Table IV SC solid content These data show two transition temperatures Tg, the first Tg belonging to the core polymer and the second Tg belonging to the roof polymer.

Example 9 A latex in which PARSOL® MCX was incorporated into the polymer particles was prepared analogously to that described in Examples 4 and 5.

The following Examples 10 and 11 relate to the sun's protective compositions. the abbreviations and trade names selected have the following meaning: ARLACEL P135 PEG-30 dipolyhydroxies tearate marketed as ICI ARLAMOL E POP- (15) - stearyl alcohol marketed as ICI ARLAMOL HD Heptamethylnonano marketed as ICI BHT But i lhi droxit oluol (2,6-di-tert-butyl-4-methyl) phenol BRIJ 72 POE- (2) -alcohol stearyl marketed as ICI BRIJ 721 POE- (21) -alcohol stearyl marketed as ICI EDTA Disodium EDTA EDTA marketed as BASF LANETTE O Cetearyl alcohol marketed by Henkel PARSOL®340 Octocrylene marketed by Roche PARSOL®1789 Butyl methoxydibenzoylmethane marketed by Roche PARSOL®5000 Methyl benzylidene camphor marketed by Roche PARSOL®HS Phenyl benzylimidazole sulfonic acid marketed by Roche PARSOL®MCX 2-ethylhexyl-p-methoxycinnamate marketed by Roche PHENONIP Phenoxyethanol ( and) methylparaben (and) butylparaben (y) propylparaben marketed by ÑIPA Propylene glycol 1,2 propanediol marketed by BASF SILBIONE Oil Ciclomet ixone marketed 70047 V20 by Rhóne-Poulenc SILICONE 1401 Cyclomethicone and dimethiconil Fluida marketed by Dow Corning SILICONE 5225 Cyclopentasiloxane and Formulation dimethicone copolyol Auxi liar marketed by Dow Corning SILICONE DC 344 Cyclomethicone marketed by Dow Corning SILICONE DC 5200 Dimethicone copolyol marketed by Dow Corning UMORDANT P Na-Lactate and Na-PCA and urea and hydrolyzed vegetable protein and Aspa Example 10 Preparation of a sun protection .O / W lotion containing 23% by weight of encapsulated PARSOL® 1789 prepared according to Example 4.

Ingredients% weight / weight ARLAMOL E 5, 00 ARLAMOL HD 5, 00 BRIJ 72 3, 00 BRIJ 721 2, 00 ARLACEL P135 0, 50 LANETTE O 5, 00 Stearic acid 1, 50 Oil SILBIONE 70047 V20 1, 00 BHT 0, 10 PHENONIP 0, 60 Deionized water esp up to 100, 00 1% solution of Goma Xantano 6, 00 Propylene Glycol 4, 00 UMORDANT P 1, 00 PARSOL®1789 encapsulated 23, 00 PARSOL® MCX 5, 00 The organic phase containing the UV filters was heated to 75 ° C, and then the precancelated aqueous phase (75 ° C) was added with stirring. The resulting emulsion was cooled to room temperature.

Example 11 Preparation of a sun-protecting O / W lotion containing 23% by weight of encapsulated PARSOL® 1789 prepared according to Example 4.

Ingredients% weight / weight SILICONE 1401 Auxiliary Fluid of 10, 00 Substantivity SILICONE 3225 Auxiliary Formulation 10, 00 SILICONE DC 344 10, 00 SILI-CONA DC 5200 2, 00 EDTA BD 0, 10 PHENONIP 0, 60 PARSOL® HS 3, 00 Glycerol 5, 00 Water deionized esp up to 100, 00 PARSOL (R9 1789 encapsulated 23, 00 10% Sodium Hydroxide at pH 7 The organic phase containing the UV filters was heated to 75 ° C, and subsequently the preheated aqueous phase (75 ° C) was added under agitation. The resulting emulsion was cooled to room temperature.

It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Having described the invention as above, the content of the following is claimed as property.

Claims (19)

Claims

1. A photo-stable, cosmetic or pharmaceutical light screening composition characterized in that it contains a dibenzoyl methane UV-A screening agent and a UV-B screening agent of p-me t oxycinnamate, wherein one of the screening agents is incorporated in a polymeric matrix.

2. The light screening composition as claimed in claim 1, characterized in that it contains about 0.5% by weight to about 5% by weight of a dibenzoyl methane UV-A screening agent incorporated in a polymer latex; about 1% by weight to about 15% by weight of a UV-B screening agent of p-methoxycinnamate; and optionally, other conventional UV-A and UV-B screening agents.

3. The light screening composition as claimed in claim 1, characterized in that it contains about 15% by weight of the UV-B screening agent of p-methoxycinnamate incorporated in a polymeric latex; about 0.5% by weight to about 5% by weight of a dibenzoyl methane UV-A screening agent; and optionally, other conventional UV-A and UV-B screening agents.

4. The light screening composition according to any of claims 1 to 3, characterized in that the UV-A screening agent of dibenzoyl methane is 4-tert-butyl-4'-methoxydibenzoyl methane and the agent of Screening of the UV-B rays of p-methoxycinnama to is 2-ethylhexyl p-methoxycinnamate.

5. The light screening composition according to any of claims 1 to 4, characterized in that the polymeric latex is a stable colloidal dispersion of polymer particles in an aqueous phase or based on an aqueous phase including polymers and / or copolymers of unifunctional monomers and / or multifunctional monomers.

6. The light screening composition according to claim 5, characterized in that the unifunctional monomer is selected from C 1 -C 8 -alkyl (meth) acrylate, Cl-C 8 -alkyl 1 (me t) acrylic acid, acrylic acid, styrene, ethylene, propylene, butylene, butadiene, isopropene, isobornylmethacrylate (IBOMA), tri-f luoroet-il methacrylate or perfluoroalkyl 1-2-ethylacrylate.

7. The light screening composition according to claim 5, characterized in that the multifunctional monomer is selected from allyl methacrylate (ALMA) or ethylene glycol dimethacrylate (EGDMA).

8. The light screening composition according to any of claims 5 to 7, characterized in that the polymer particles have a glass transition temperature between about 50 ° C and about 100 ° C.

9. The light screening composition according to any of claims 1 to 8, characterized in that the polymeric latex is a stable colloidal dispersion of copolymer particles of methyl methacrylate (MMA) and acrylic acid (AA) crosslinked with allyl methacrylate (ALMA) and ethylene glycol dimethacrylate (EGDMA) or isobornylmethacrylate (IBOMA) crosslinked with allylmethacrylate (ALMA).

10. The light screening composition according to any of claims 5 to 9, characterized in that the polymer particles have a matrix structure within which the dibenzoyl methane UV-A screening agent or the screening agent of The UV-B rays of p-methoxycinnamate are distributed homogeneously throughout the volume of the particles.

11. The light screening composition according to any of claims 5 to 9, characterized in that the polymer particles have a polymeric core surrounded by a polymeric cover, in which the core contains the UV-A screening agent of dibenzoyl methane or the UV-B screening agent of p-methoxycinnamate.

12. The light screening composition according to claim 11, characterized in that the core and the cover portions of the core / shell polymer particles have the same chemical composition with respect to the monomers used.

13. The shielding composition of the - light according to claim 11, characterized in that the core and the cover portions of the core / shell particles affect their chemical composition.

14. The light screening composition according to claim 13, characterized in that a) the core consists of a polymer and / or copolymer of methyl methacrylate (MMA) and acrylic acid (AA) crosslinked with allyl methacrylate (ALMA) and ethylene glycol dimethacrylate (EGDMA) ) or is composed of isobornyl methacrylate or (IBOMA) cross-linked with allyl methacrylate (ALMA); and b) the cover consists of a hydrophilic polymer or fluorinated polymer chains.

15. The light screening composition according to any of claims 1-14, characterized in that it is for cosmetic or pharmaceutical use for human skin or hair.

16. A process for the preparation of polymeric latex, characterized in that the polymer particles have a matrix structure within which the dibenzoyl methane UV-A screening agent or the UV-B screening agent of p-methoxycinnamate is distributed homogeneously throughout the volume of the particles and the process consists of a) dissolution of the UV-A screening agent of dibenzoyl methane or the UV-B screening agent of p-methoxycin in a mixture of monomers; b) preemulsification of the solution of step a) in an aqueous solution containing an emulsifier; cl) continuously introducing the preemulsion of step b) into a reactor containing an aqueous initiator solution or c2) introducing a small amount of the preemulsion from step b) into a reactor containing an aqueous initiator solution, thereby obtaining polymer particles and then the introduction of the remaining pre-emulsion.

17. A process for the preparation of polymeric latex, characterized in that the polymer particles have a polymeric core surrounded by a polymeric cover, where the process consists of a polymerization process of the two-step emulsion, comprising a first step of polymerization to obtain the particles polymer particles and a second polymerization step to obtain polymer particles having at least one shell surrounding the core.

18. A method of photosetting mixtures of a UV-A screening agent of dibenzoyl methane and a UV-B screening agent of p-oxycinnamate in a light shielding composition, characterized because the method comprises the incorporation of one of the light screening agents in a polimeric latex.

19. The invention is substantially as previously described, especially with reference to the Examples.