EP2861201A1

EP2861201A1 - Aqueous dispersion of polymer particles, film-forming composition containing same and uses thereof

Info

Publication number: EP2861201A1
Application number: EP13731398.7A
Authority: EP
Inventors: Ludwik Leibler; François Tournilhac; Aggeliki TRIFTARIDOU; Eva-Maria LEUSCHNER; Stéphane Auguste; Jean-Marc Pernot
Original assignee: Centre National de la Recherche Scientifique CNRS; Ecole Superieure de Physique et Chimie Industrielles de Ville Paris; Vivatech Co
Current assignee: Centre National de la Recherche Scientifique CNRS; Ecole Superieure de Physique et Chimie Industrielles de Ville Paris; Urgo Recherche Innovation et Developpement
Priority date: 2012-06-08
Filing date: 2013-06-07
Publication date: 2015-04-22
Also published as: US20150174042A1; WO2013182828A1; JP2015519376A; CA2875604A1; CN104684532B; HK1203415A1; BR112014030566A2; FR2991684A1; FR2991684B1; US9642790B2; CN104684532A; JP6294313B2

Abstract

The present invention concerns an aqueous dispersion of multiphase polymer particles in which the polymer particles comprise at least two separate phases, the internal phase being formed by polymerisation in the presence of a crosslinking agent, said dispersion further comprising a surfactant chosen from amino acid derivatives. The invention also concerns a film-forming composition comprising said aqueous dispersion of polymer particles. The invention also relates to a film obtained after application of said film-forming composition. This film dries very quickly, is water resistant, and has good adhesion, elasticity and breaking strength properties. The invention also concerns the use of said film for protecting surfaces of the skin or mucous membranes, wounds, injuries and/or skin disorders.

Description

AQUEOUS DISPERSION POLYMER DEPARTICLES, FILM-FORMING COMPOSITION CONTAINING THE SAME AND USES THEREOF

The invention relates to an aqueous dispersion of multiphase particles of polymers, and to its use in film-forming compositions that may for example be applied to skin, mucous membranes, wounds, lesions and / or skin disorders. The invention also relates to the use of said dispersions to form physiologically acceptable films that can be applied to the skin.

Prior art

Physiologically acceptable formulations comprising latex type film forming compositions (aqueous polymer dispersions) are well known to those skilled in the art.

In its US patent application 2010/0021409 Procter & Gamble discloses, for example, a composition for use as a shaving foam. Said composition comprises one or more film-forming materials dispersed in an aqueous phase by surfactants. The film-forming materials may be polymers such as polyvinylpyrrolidone or hydroxyethylcellulose or copolymers such as a styrene-acrylate or styrene-butadiene latex. Several surfactants are described such as in particular sarcosinic acid derivatives and more particularly sodium W-myristoylsarcosinate. The compositions according to this document are shaving foams and in particular do not make it possible to form an isolatable film which is elastic, water-resistant, which has good breaking strength and durably protects surfaces such as, for example, the skin.

Latex may in particular be used to form isolable films. In US 5,173,291, for example, 3M discloses a latex composition comprising an aqueous copolymer dispersion comprising:

a "soft" monomer whose homopolymer corresponds to a Tg of less than -15 ° C., such as butyl acrylate,

a "hard" monomer whose homopolymer corresponds to a Tg greater than -5 ° C., such as methylmethacrylate, and

a monomer capable of complexing iodine, such as N-vinylpyrrolidinone; said composition also comprising iodine for its antimicrobial properties and for stabilizing the aqueous dispersion as well as a surfactant to help disperse the latex particles in the aqueous phase.

This film-forming composition is intended to form a protective film on the skin, such as in particular a dressing.

However, films formed using these compositions have limited mechanical properties, especially in terms of elasticity and breaking strength.

There is therefore a need for new film-forming compositions capable of easily and quickly forming breakable, adherent insulative films having good elasticity and water-resistant properties.

Surprisingly, it has been found that it is possible to prepare films which dry rapidly, having excellent adhesion, elasticity and resistance to water and to breaking properties by means of aqueous dispersion of multiphase particles of polymers in which the polymer particles comprise at least two distinct phases having different Tg's, the inner phase being formed by polymerization in the presence of a crosslinking agent, said dispersion comprising a surfactant selected from the group consisting of 'amino acids. The film formed from this dispersion comprises at least two different Tg.

The invention thus has, according to a first aspect of the invention, an aqueous dispersion of multiphase particles of polymers in which the polymer particles comprise at least two distinct phases:

a first phase formed by a soft polymer P1 having a glass transition temperature (Tgi) of less than 20 ° C,

a second phase formed by a hard polymer P ₂ having a glass transition temperature (Tg ₂ ) greater than 60 ° C.,

said dispersion comprising a surfactant selected from amino acid derivatives and wherein the polymer Pi is formed by polymerization in the presence of a crosslinking agent. According to a second aspect, the invention also relates to a film-forming composition comprising, in a physiologically acceptable medium, an aqueous dispersion of multiphase particles of polymers.

The invention also relates, according to a 3 ^rd aspect, a film having at least two different Tg, said film comprising multiphase polymer particles and a surfactant, wherein the polymer particles comprise at least two distinct phases:

a first phase formed by a soft polymer Pi having a glass transition temperature (Tg less than 20 ° C.,

wherein said surfactant is selected from amino acid derivatives and wherein the polymer Pi is formed by polymerization in the presence of a crosslinking agent.

Finally, according to a fourth aspect, the subject of the invention is the use of the film previously described, for protecting skin surfaces, mucous membranes, wounds, lesions and / or skin conditions.

Aqueous dispersion

The present invention relates to an aqueous dispersion of multiphase particles of polymers. For the purposes of the present application, the term "aqueous dispersion" means a suspension of solid particles in a liquid phase comprising at least water.

The aqueous phase also comprises at least one surfactant chosen from amino acid derivatives, and optionally an oxidation / reduction system and / or a pH regulator and / or one or more pharmaceutical or cosmetic agents and / or one or more physiologically additive additives. acceptable.

The aqueous phase may especially be present in the dispersion according to the invention in a content ranging from 20 to 75%, preferably from 40 to 70% by weight, relative to the weight of the aqueous dispersion. Multiphasic polymer particles

For the purposes of the present invention, the multiphase particles of polymers are solid particles of polymers which are dispersed in the aqueous phase.

By polymer is meant, in the sense of the present invention, a homopolymer or a copolymer.

Said multiphasic particles comprise at least two phases, each phase consisting of a polymer having very distinct properties, such as, in particular, different glass transition temperatures (Tg) for each phase.

Within the meaning of the present invention, by glass transition temperature (Tg) of each phase of multiphase polymer particles, is meant either the Tg of the homopolymer as referenced in the literature, or the Tg of the copolymer calculated by the law of the Fox-Flory blends. Indeed, the Tg of each phase is not directly measurable on the multiphase particles as such.

When a phase of the particle consists of a copolymer, the skilled person can easily calculate the Tg of this phase using in particular the law of Fox-Flory mixtures. Thus, if a phase of the multiphasic particle consists of a copolymer which has a mass fraction X of a monomer A having a glass transition temperature Tg (A) and a mass fraction Y of a monomer B having a temperature of glass transition Tg (B), then the glass transition temperature of the copolymer Tg (AB) can be estimated by applying the following relation, the temperatures being expressed in Kelvin:

1 ₌ XY

Tg (AB) Tg (A) Tg (B)

According to one embodiment, the first phase formed by the soft-matter polymer Pi may be the internal phase of the particle (also called the core) and the second phase formed by the hard-type polymer P ₂ may be the external phase of the particle (also called bark).

In particular, in the context of the invention, the polymer particles may be at least two-phase and have a core / bark structure. The softness of the polymer Pi can be reinforced by choosing a polymer Pi having a Tgi of less than 20 ° C, preferably less than 5 ° C and more preferably still lower than 0 ° C.

The hard nature of the polymer P ₂ can be reinforced by choosing a polymer P ₂ having a Tg ₂ greater than 60 ° C, preferably greater than 70 ° C and more preferably still greater than 80 ° C.

According to a particular embodiment, the polymer Pi represents 60 to 90% by weight of the particles and the polymer P ₂ represents 10 to 40% by weight of the particles.

The first phase of the polymer particles according to the invention is obtained by polymerization of one or more monomers and at least one crosslinking agent. The second phase of the polymer particles according to the invention can be obtained by polymerization of one or more monomers and optionally of one or more crosslinking agents.

The presence of a crosslinking agent in the first phase may in particular make it possible to structure said particle by crosslinking and in particular the first phase of said particle, which makes it possible to have a composition capable of forming a film having two glass transition temperatures of controlled and reproducible manner.

According to a particular embodiment, the polymer P 1 may comprise 0.5 to 10%, preferably 1 to 7%, more preferably 2 to 5% by weight of units obtained by polymerization of a crosslinking agent, preferably chosen from group (II).

According to one particular embodiment, the polymer Pi can comprise:

90 to 99.5%, preferably 93 to 99%, more preferably 95 to 98% by weight of units obtained by polymerization of at least one monomer chosen from group (I); and

- 0.5 to 10%, preferably 1 to 7%, more preferably 2 to 5% by weight of units obtained by polymerization of a crosslinking agent, preferably selected from group (II). According to another particular embodiment, the polymer P ₂ can comprise 95 to 99.5%, preferably 97 to 99%, more preferably 100% by weight of units obtained by polymerization of at least one monomer chosen from the group (I ).

When the second phase of the polymer particles is crosslinked, the polymer P ₂ may comprise 0.5 to 5%, preferably 1 to 3% by weight of units obtained by polymerization of a crosslinking agent, preferably chosen from the group (II).

Within the meaning of the present application, the monomers of group (I) can be selected from alkyl (Ci-Ci ₆₎ esters of (meth) acrylic acid such as methyl (meth) acrylate, (meth) ethyl acrylate and butyl (meth) acrylate, hydroxy-alkyl esters of (meth) acrylic acid, vinyl esters of linear or branched carboxylic acids such as vinyl acetate and vinyl stearate, styrene, alkylstyrenes such as methylstyrene, haloalkylstyrenes such as chloromethylstyrene, (meth) acrylamide, acrylonitrile, vinyl chloride, (meth) acrylic acids and their derivatives such as anhydrides, monomers containing acids or basic such as itaconic acid, fumaric acid, crotonic acid, maleic acid, silane (meth) acrylic or vinyl monomers such as methacryloxypropyl triethoxy or triisopropoxysilane, the monomers containing aceto groups acetoxy, such as acetoacetoxyethyl (meth) acrylate, and mixtures thereof,

The crosslinking agents of the group (II), within the meaning of the present application, can be chosen from the following monomers: allyl esters or (Cr Ci6) alkyl esters of monocarboxylic or dicarboxylic acids, such as allyl acrylate allyl methacrylate, diallyl maleate or phthalate and dimethyl maleate, conjugated dienes such as butadiene and isoprene, polyol poly (meth) acrylates such as ethylene glycol dimethylacrylate or triethylene glycol, 1,3-1,4-butylene glycol dimethylacrylate, 1,4-butanediol diacrylate and pentaerythritol tetraacrylate, trimethylolpropane triacrylate, polyvinylbenzenes such as divinylbenzene or trivinylbenzene and polyallyl derivatives such as triallyl cyanurate , triallyl isocyanurate and triallyl trimesate, and mixtures thereof. According to a preferred embodiment, the monomers of group (I) of the polymer Pi are chosen from butyl acrylate, methyl methacrylate, and mixtures thereof.

According to another preferred embodiment, the crosslinking agents of the group (II) of the polymer Pi are chosen from diallyl maleate, dimethylmaleate, 1,4-butanediol diacrylate, and mixtures thereof.

According to another preferred embodiment, the monomer of the group (I) of the polymer P ₂ is methyl methacrylate.

According to a preferred embodiment, the polymer P ₂ of the aqueous dispersion according to the invention may contain at least 91%, preferably at least 95% and even more preferably 100% by weight of units obtained by polymerization of hydrophobic monomers. Indeed, such levels of hydrophobic monomers can allow, during the formation of the corresponding film, to obtain a hard film, non-tacky and water-resistant. These properties are, on the contrary, altered when the outer layer of the particles contains more than 10% of hydrophilic monomers.

In general, the hydrophobic character of a monomer is defined as its insolubility in water or its lack of affinity for water. When a polymer consists of hydrophobic monomers, said polymer is also considered hydrophobic. Within the meaning of the present application, the hydrophobicity of a polymer can be defined using the solubility parameter δ described in "Properties of Polymers" by DW Van Krevelen, 1990, ^3rd edition, page 200. This parameter classify the different polymers according to their affinity for water. According to the invention, a polymer is hydrophobic if its δ is less than 26.

According to a preferred embodiment, the second phase of the polymer particles of the present invention does not contain units obtained by polymerization of monomers comprising an acid function.

According to a particular embodiment, the polymer particles according to the invention comprise an intermediate phase, formed by a polymer P ,, interposed between the first phase and the second phase. Advantageously, the polymer P, of the intermediate phase has a glass transition temperature Tg, between 20 and 60 ° C. The polymer P may in particular be formed by polymerization in the presence of a crosslinking agent. The polymer Pi may comprise 90 to 99.5%, preferably 93 to 99%, more preferably 95 to 98% by weight of units obtained by polymerization of at least one monomer chosen from group (I). In addition, the polymer P 1 may comprise 0.5 to 10%, preferably 1 to 7%, more preferably 2 to 5% by weight of units obtained by polymerization of a crosslinking agent chosen from group (II). Preferably, the monomers of the group (I) of the polymer P are chosen from butyl acrylate, methyl methacrylate, and mixtures thereof. Preferably, the crosslinking agents of the group (II) of the polymer P are chosen from diallyl maleate, dimethylmaleate and 1,4-butanediol diacrylate, and mixtures thereof.

According to a particular embodiment, the multiphase particles of polymers are substantially spherical and have a size of between 15 and 300 nanometers, preferably between 30 and 100 nanometers. The multiphase particles of polymers may in particular be present in the aqueous dispersion according to the invention in a content of between 25 and 70% by weight, preferably between 30 and 70% by weight, relative to the weight of the aqueous dispersion.

Surfactant The aqueous dispersion of multiphase particles according to the invention further comprises at least one surfactant. The surfactant makes it possible in particular to stabilize the suspension of the multiphasic particles of polymers in the aqueous phase.

The surfactant used in the dispersion according to the invention is an amino acid derivative, such as in particular a derivative of sarcosinic acid or glutamic acid. The surfactant derived from amino acid may in particular be chosen from:

Sodium V-lauroylglutamate, disodium V-cocoylglutamate, sodium V-cocoylglutamate, sodium V-lauroylsarcosinate, sodium V-myristoylsarcosinate, sodium V-cocoylsarcosinate and / or V-cocoylglutamate. sodium oleoylsarcosinate, ammonium β-lauroylsarcosinate, and mixtures thereof. According to a preferred embodiment, the surfactant is chosen from sodium lauroylsarcosinate, sodium V-myristoylsarcosinate and sodium lauroylglutamate, preferably sodium lauroylsarcosinate.

The choice of a surfactant derived from amino acids in the aqueous dispersions according to the invention makes it possible, in particular, to prepare aqueous dispersions of polymers which make it possible to obtain films having improved mechanical properties and in particular better elasticity and better strength. at break and better deformation at break.

In addition to improving the mechanical properties of the film, the surfactants derived from amino acids have a very low toxicity to the environment (these surfactants are biodegradable) but also for humans. This low toxicity is therefore an asset for the applications of the film according to the invention on the skin, wounds and / or mucous membranes. Among the other significant advantages of these surfactants, one can also cite their compatibility with the pH of the skin and their low irritating potential.

In addition, the Applicant has found, surprisingly, that it was possible to further optimize the properties of the film obtained after application of the film-forming composition by adjusting the concentration and the nature of the surfactant. Indeed, when the concentration of surfactant is too low, the film can lose elasticity and become brittle. Conversely, when the surfactant concentration is too high, the film may tend to become opaque and turn white. Indeed, it has been found, when the molar monomer to surfactant ratio is of the order of 30 or less than 30, the film obtained tends to become white and when this ratio is of the order of 190 or greater than 190 , the resulting film has a tendency to crack.

Thus, the concentration of the surfactant in the aqueous dispersion according to the invention is preferably between 0.1 and 5% by weight, relative to the dry matter weight of the aqueous dispersion, preferably between 0.4 and 5% by weight. weight, and even more preferably between 0.7 and 2% by weight. Oxidation / reducer system

The aqueous phase of the dispersion according to the invention may optionally comprise an oxidation / reduction system which makes it possible to promote the initiation of the polymerization. In the context of the invention, the oxidation / reduction system may be chosen from tert-butyl hydroperoxide / sodium bisulfite to which sodium sulfoxylate formaldehyde, potassium persulfate / sodium bisulfite, to which may be added, may be added. sodium sulphoxylate formaldehyde, ammonium persulfate / sodium bisulfite to which sodium sulphoxylate formaldehyde, potassium persulfate / sodium hydroxymethanesulphinate, and mixtures thereof are added.

The preferred redox / reductant system is potassium persulfate / sodium bisulfite and sodium sulfoxylate formaldehyde.

The oxidant and reducing agent concentration in the aqueous dispersion according to the invention may be between 0.01 and 5% by weight, preferably between 0.1 and 2% by weight, relative to the dry weight of the dispersion. aqueous.

PH regulator

The aqueous phase of the dispersion according to the invention may also comprise a pH regulator which may in particular make it possible to adjust the pH so as to optimize the polymerization. The pH regulators used in the present invention are those commonly used by those skilled in the art. Such regulators are described in the following publications: CRC Handbook of Chemistry and Physics 76 ^th ed. (page 8- 42) Bower, VE and RGJ Res. Nat. Off. Stand. 55, 197, 1955 and Bats RG and Bower VE Anal. Chem., 28, 1322, 1956. Preferably the pH regulator is obtained by mixing in various proportions aqueous 0.1 M solutions of KH ₂ PO ₄ (potassium dihydrogenphosphate) and NaOH (sodium hydroxide) as described in FIG. Handbook of Chemistry and Physics, 76th ed. Chapter 8, pp. 8-42. According to one particular embodiment, for a pH 6.0 regulator, 50 ml of KH ₂ PO ₄ (0.1 M) and 5.6 ml of NaOH (0.1 M) are mixed in a 100 ml flask. and the volume is made up to 100 mL with deionized water. For a pH 7.0 regulator, 50 ml of KH ₂ PO ₄ (0.1 M) and 29.1 ml of NaOH (0.1 M) are mixed in a 100 ml flask and the volume is 100 mL with deionized water. For a pH 7.5 regulator, 50 ml of KH ₂ PO ₄ (0.1 M) and 40.9 ml of NaOH (0.1 M) are mixed in a 100 ml flask and the volume is 100 mL with deionized water.

The pH regulator can also control the acid-base form of the surfactant. Indeed, the surfactants derived from amino acids can be in two forms depending on the pH of the reaction medium:

the neutral form when the pH is greater than the pKa of the surfactant,

the basic form in which the acid function has become a sodium carboxylate when the pH is lower than the pKa of the surfactant.

For stability reasons, it is preferable that the surfactant is in its basic form, which corresponds to a pH of the aqueous dispersion greater than one unit above the pKa of the surfactant used (pH> pKa +1).

In general, the pka of the surfactants derived from amino acids within the meaning of the present invention must be lower than the pH of the final emulsion. The pKa may especially be between 2 and 7 and preferably between 3 and 5. The concentration of pH regulator in the aqueous dispersion may especially be between 5 mmol / L and 100 mmol / L, preferably between 10 mmol / L. and 15 mmol / L, the concentration being expressed in moles of pH regulator per liter of aqueous dispersion.

In the case where the surfactant precipitates at a pH in the region of 5, a buffer solution having a pH of between 5.8 and 8.0 may, for example, be prepared from 50 ml of a solution of potassium dihydrogenphosphate ( 0.1 molar) + x mL of NaOH (0.1 molar), where x is a tabulated value as a function of the desired pH. Pharmaceutical or cosmetic agents

The aqueous dispersion according to the invention may comprise, in addition to the components mentioned above, one or more pharmaceutical or cosmetic agents (or active agents) such as, in particular, anti-bacterial agents, antiseptics, anti-virals, antifungal agents. , painkillers, anti-inflammatories, healing agents, moisturizers, depigmenting agents, keratolytic agents, restructuring agents, anesthetics and sunscreens.

In particular, the active agents that can be introduced into the composition according to the invention can be chosen from: anti-bacterials such as Polymyxin B, penicillins (Amoxycillin), clavulanic acid, tetracyclines, Minocycline, chlorotetracycline, aminoglycosides, Amikacin, gentamicin, neomycin, silver and its salts (silver sulfadiazine), probiotics;

antiseptics such as sodium mercurothiolate, eosin, chlorhexidine, phenylmercury borate, hydrogen peroxide, Dakin liquor, triclosan, biguanide, hexamidine, thymol, Lugol, Povidone iodine, Merbromine, Benzalkonium and Benzethonium Chloride, ethanol, isopropanol;

anti-virals such as Aciclovir, Famciclovir, Ritonavir;

antifungals such as polyenes, Nystatin, Amphotericin B, Natamycin, imidazoles (Miconazole, Ketoconazole, Clotrimazole, Ecconazole,

Bifonazole, Butoconazole, Fenticonazole, Isoconazole, Oxiconazole, Sertaconazole, Sulconazole, Thiabendazole, Tioconazole), triazoles (Fluconazole, Itraconazole, Ravuconazole, Posaconazole, Voriconazole), allylamines, Terbinafine, Amorolfine, Naftifine, Butenafine; Flucytosine (antimetabolite), Griseofulvin, Caspofungin, Micafungin;

anti-pain agents such as paracetamol, codeine, dextropropoxyphene, tramadol, morphine and its derivatives, corticosteroids and derivatives; anti-inflammatories such as glucocorticoids, nonsteroidal anti-inflammatory drugs, aspirin, ibuprofen, ketoprofen, flurbiprofen, diclofenac, aceclofenac, ketorolac, meloxicam, piroxicam, tenoxicam, Naproxen, Indomethacin, Naproxcinod, Nimesulide, Celecoxib, Etoricoxib, Parecoxib, Rofecoxib, Valdecoxib, Phenylbutazone, Niflumic acid, Mefenamic acid;

the active agents promoting healing such as retinol, vitamin A, vitamin E, N-acetyl-hydroxyproline, extracts of Centella Asiatica, papain, silicones, essential oils of thyme, niaouli, rosemary and of sage, hyaluronic acid, synthetic polysulfated oligosaccharides having 1 to 4 units such as the potassium salt of octasulfated sucrose, the silver salt of octasulfated sucrose or sucralfate, Allantoin;

moisturizing agents such as hyaluronic acid, urea, glycerol, fatty acids, modulators of aquaporins, vegetable oils, chitosan, certain sugars including sorbitol, butters and waxes; depigmenting agents such as kojic acid (Kojic Acid SL®-Quimasso (Sino Lion)), Arbutin (Olevatin® - Quimasso (Sino Lion)), the mixture of palmitoylpropyl of sodium and white water lily extract (Sepicalm® - Seppic), undecylenoyl phenylalanine (Sepiwhite® - Seppic), licorice extract obtained by fermentation of Aspergillus and ethoxydiglycol (Gatuline Whitening® - Gattefossé), octadecenedioic acid (ODA White® - Sederma) alpha-arbutin (Alpha-arbutin®, SACI-CFPA (Pentapharm)), Arctophylos Uva Ursi leaf extract (Melfade-J® - SACI-CFPA (Pentapharm)), the Gigawhite® complex plant blend (SACI-CFPA (Alpaflor)), diacetyl boldine (Lumiskin® - Sederma), mandarin extract from Japan (Melaslow® - Sederma), lemon extract mixture enriched with citric acid and cucumber extract (Uninontan®U-34 - Unipex), the mixture of Rumex occidentalis extract and vitamin C (Tyrostat® 11 - Unipex), oligopeptid es (Melanostatin 5® - Unipex), kojic dipalmitate (KAD-15® - Quimasso (Sino Lion)), LCW's Vegewhite® natural complex, wheat germ extracts (Clariskin® II - Silab), ethyldiamine triacetate (EDTA); keratolytic agents such as salicylic acid, zinc salicylate, ascorbic acid, alpha hydroxy acids (glycolic acid, lactic acid, malic acid, citric acid, tartaric), extracts of Silver Maple, Griottier, Tamarind, Urea, Keratin® (Sederma) topical retinoid, Bacillus Subtilis fermentation proteases, Linked-Papain® (SACI-CFPA), papain (a proteolytic enzyme derived from papaya fruit); - restructuring assets (for example restructuring of the integuments) such as silica derivatives, vitamin E, chamomile, calcium, horsetail extract, silk Lipester;

anesthetics such as benzocaine, lidocaine, dibucaine, pramoxine hydrochloride, bupivacaine, mepivacaine, prilocaine, etidocaine; - sunscreens, such as chemical filters (Oxybenzone, Sulisobenzone, Dioxybenzone, Tinosorb S®, Avobenzone, 2-ethoxyethyl p-methoxycinnamate, Uvinul® A +, Mexoryl® XL, Methoxycinnamate or octyl octinoxate, Salicylate or octisalate d octyl, octyl triazone or Uvinul® T 150, methyl salicylate, meradimate, enzacamene, MBBT or Tinosorb® M, octyl cyanophenylcinnamate or Parsol® 340, para-aminobenzoic acid, Ensulizole, Parsol® SLX or Polysiloxane-15 or Benzylidene malonate polysiloxane, Parsol® MCX or ethylhexyl methoxycinnamate, triethanolamine salicylate or trolamine salicylate, Mexoryl® SX or terephthalylidene dicamphosulphonic acid) and mineral filters (zinc oxides, titanium dioxide, kaolin).

During the preparation of the aqueous dispersion according to the invention, it is possible to choose to incorporate the active agent into the inner phase or into the outer phase of the multiphasic particle of polymers or to leave it free in solution. We choose the phase in which it is desired to incorporate the active agent according to the chemical properties of the active agent. It will also be possible to choose the phase in which the active agent is integrated depending on whether it is desired that the latter be salted out or not. Thus, for example, to incorporate the active in one of the phases of the multiphase particles of polymers, it may in particular be introduced simultaneously to the monomers that form the polymer of this phase.

According to a particular embodiment, the active agent incorporated in the internal phase of the multiphasic particle of polymers is a sunscreen, such as Parsol® MCX. This sunscreen is hydrophobic and should preferably stay on the surface of the skin, ie not to be salted out, in order to be able to exert its filtering properties and protect the skin from UV-B rays. Incorporation of Parsol® MCX in the internal phase of the particle may, for example, allow good dispersion and good persistence of the active agent on the skin once the film has been applied thereto. Thus, if a dispersion of multiphase particles of polymers comprising a sunscreen in their internal phase is applied to the skin, a film particularly resistant to water and effectively protecting the skin from the sun is obtained. This may in particular allow to avoid repeated applications of sunscreen, while providing optimal sun protection to the user. Indeed, it has been shown that no release of sunscreen is observed when the films obtained are washed with water.

According to another particular embodiment, the active agent is free in solution in the aqueous dispersion of multiphase particles of polymers or in the composition comprising said dispersion. In the context of the incorporation of an active agent, such as in particular a sunscreen, intended to protect a surface, such as the skin, it is preferable for said active agent to be incorporated in one of the phases of the polymer particles. rather than being free in solution. In fact, the active agent is thus better dispersed within the film (more homogeneous dispersion) and thus adheres better to the skin, which gives the skin excellent protection against the sun's rays.

Physiologically acceptable additives

The aqueous dispersion according to the invention may comprise, in addition to the components mentioned above, one or more physiologically acceptable additives such as, for example, perfumes, flavors, dyes, pigments, matting agents, rheological agents, preservatives.

In the same way as for pharmaceutical or cosmetic active agents, it is possible, depending on the solubility of the additive and the polymerization step to which said additive is added, to choose whether said additive will be incorporated in the internal or external phase. multiphase particles of polymers or if it will remain free in solution in the aqueous dispersion according to the invention. Method of preparation of the aqueous dispersion

The aqueous dispersion according to the invention can in particular be obtained by emulsion polymerization according to the techniques well known to those skilled in the art. During the emulsion polymerization, the surfactant makes it possible to form monomer droplets (also called micelles) within which the polymerization takes place.

In the context of the invention, it is possible to prepare, in a first step, the soft-matter polymer P 1 constituting, for example, the internal phase of the particles in the presence of a crosslinking agent, preferably chosen from the group (II). ), and then proceed to the preparation of the polymer P ₂ hard character constituting the outer phase of the particles.

When the polymer particle comprises an intermediate phase formed by a polymer Pi, it is possible, in a first step, to prepare the polymer Pi constituting the internal phase of the particles in the presence of a crosslinking agent, to proceed, in a second step, to the preparation of the polymer P constituting the intermediate phase of the particles and finishing with the preparation of the polymer P ₂ constituting the external phase of the particles.

For each step, the polymerization reaction is preferably carried out under an inert atmosphere at a temperature between 25 and 150 ° C depending on the nature of the oxidation / reducing system used.

According to a preferred embodiment, the monomers are added in the aqueous phase, either in pure form or in the form of a pre-emulsion with a part of the water and at least one surfactant, over a period of time ranging from for a preparation of about 100 grams of aqueous dispersion, between 10 minutes and 3 hours, preferably between 15 and 90 minutes.

Film-forming composition

Another subject of the invention is a film-forming composition comprising, in a physiologically acceptable medium, an aqueous dispersion of multiphase particles of polymers according to the invention. By physiologically acceptable medium is meant, within the meaning of the present invention, a medium that is compatible with the skin, mucous membranes, wounds, lesions and / or skin disorders.

The physiologically acceptable medium may include water. According to a preferred embodiment, the physiologically acceptable medium does not include any other solvent than water.

The composition according to the invention may comprise, in addition to the aqueous dispersion of multiphase particles, one or more pharmaceutical or cosmetic agents (or active agents) as defined above. The composition according to the invention may also comprise one or more physiologically acceptable additives as defined above.

According to a preferred embodiment, the film-forming composition according to the invention comprises only the aqueous dispersion of multiphasic particles of polymers described above. According to another preferred embodiment, the film-forming composition according to the invention comprises:

80 to 99.9% of aqueous dispersion of multiphasic particles of polymers described above,

- 0.1 to 20% of one or more pharmaceutical agents, and / or one or more additives.

According to a preferred embodiment, the film-forming composition according to the invention is liquid, that is to say that it flows under its own weight.

The film-forming compositions according to the invention may, for example, be carried out by adding, with stirring, the various active agents and additives in a dispersion of multiphase particles of polymers according to the invention, or vice versa, by adding a dispersion of multiphase particles of polymers according to the invention in an aqueous base containing the various active agents and additives. As explained above, the active agents and / or the physiologically acceptable additives can be incorporated in the inner phase or in the outer phase of the multiphasic particle of polymers or they can be free in solution in the composition according to the invention. Movie

The invention also provides, according to another aspect of the invention, a film having at least two different Tg, said film comprising multiphase particles of polymers and a surfactant, said polymer particles comprising at least two distinct phases:

The film has two distinct Tg which can be measured experimentally and which are in particular of the same order of magnitude as the Tg of each of the two phases of the polymer particles constituting said film. However, the introduction of certain pharmaceutical agents during the preparation of one of the phases of the particle may lead to a change in the Tg of the phase in which the pharmaceutical agent is introduced. In this case, a difference can be observed between one of the Tg of the film measured experimentally and that measured in the absence of said agent.

For the purposes of the present invention, the glass transition temperature of the film is understood to mean the glass transition temperature of the previously unheated (or non-annealed) film measured by AMD (Dynamic Mechanical Analysis also known as DMTA for Mechanical Thermodynamic Analysis). at 1 Hz according to the method described below.

From rectangular samples of size 10 mm x 25 mm cut in the film, dynamic mechanical analysis (AMD) measurements are carried out using of a DMA 2980 analyzer (TA instruments) in the voltage geometry of films by applying a pre-voltage of 0.01 N and operating at 1 Hz. The values of Tg are the temperatures at which the dissipation factor, tan ( delta) goes through a maximum. These values are measured at first heating at 3 ° C / min on unheated films.

By film not previously heated (or non-annealed) is meant, in the sense of the present invention, a film which has not been heated above 40 ° C.

The film may in particular be obtained by applying the film-forming composition according to the invention directly to a surface, followed by evaporation of the water. Thus, the composition can in particular be applied in a single layer on said surface. Preferably, a layer of 10 to 300 μm of the film-forming composition is produced.

The composition may be applied by any means known to those skilled in the art such as a spray, a pen, a spatula, and especially with a brush. Unexpectedly, the Applicant has found that the film obtained with the aqueous dispersions according to the invention has a particularly fast drying time, generally less than two minutes. This property is particularly suitable for producing films in situ, for example on the skin.

The Applicant has also observed that shorter drying times could still be obtained when the amount of water in the aqueous dispersion was reduced.

The film also has excellent water resistance.

According to a preferred embodiment, the film obtained after drying has excellent mechanical properties determined by the method described below: Films with a thickness of about 0.7 mm are obtained by evaporating a column of film-forming composition according to the present invention, about 2 mm high in a Teflon mold. Dumbbells in the form of DIN 53504S3A (useful length 12 mm, width 2 mm) corresponding to ISO 527-3 are obtained by punching the sheet about 0.7 mm thick using a punch. The mechanical measurements are carried out at a pulling speed of 10 mm / min using an Instron tensile machine equipped with a 500 N force sensor.

The results obtained show that the films of the present invention can have a good deformation at break that can go beyond 150%, as well as an excellent breaking strength of up to 5 MPa. In addition, the films of the present invention have an elastic regime with an elastic modulus of the order of 50 MPa and a wide plastic domain with a plastic deformation threshold of the order of 3 MPa. Finally, the film has a very good adhesion to the substrate on which it is formed without however having a tacky feel (surface tack or "tack" in English). The film also has good friction resistance.

Using the movie

According to another aspect of the invention, the film may be applied to a surface to be protected. Thus, another object of the invention is the use of the previously described film to protect skin surfaces, mucous membranes, wounds, lesions and / or skin conditions. The film according to the invention therefore finds application in the fields of dermatology and cosmetics. It may also be envisaged to apply the film according to the invention to the integuments. The film according to the invention also has applications in the field of coatings of all types of materials, such as for example leather, plastic, plaster, cardboard or paper or composite materials such as concrete or wood. .

According to a preferred embodiment, the previously described film-forming composition can be applied to the surface that it is desired to protect. After about two minutes, once the water has completely evaporated, the treated surface is covered with an elastic film. The present invention is further illustrated in the non-limiting examples described below. EXAMPLES

The following abbreviations are used in the examples: MMA: methyl methacrylate ABu: n-butyl acrylate BDA: 1,4-butanediol diacrylate DAM: diallyl maleate SB: sodium bisulfite KPS: potassium persulfate SSF: sulfoxylate formaldehyde sodium APS: ammonium persulfate

Preparation A:

250 ml of Na2HPO4 (0.49 g) are added to the 250 ml vessel and demineralized water is added to obtain 150 g of aqueous solution.

Preparation B: 2.8% by weight aqueous solution of the initiator SB (sodium bisulfite). Surfactant Preparation: N-Lauroylsarcosinate Sodium:

50.2 g of ABu (423 mmol), 23.2 g of MMA (232 mmol) are introduced into a flat-bottomed glass flask (inside diameter 55 mm) equipped with a magnetic stirrer (length 50 mm). 0.8 g of crosslinking agent BDA (4 mmol), 17 g of a 10% by weight aqueous solution of sodium N-lauroylsarcosinate (Schill + Seilacher GmbH, Perlastan L30). The medium is stirred at 600 rpm until emulsification is for at least 5 minutes. Preparation of surfactant: sodium dodecyl sulfate:

In a glass dish with a flat bottom (internal diameter 55 mm) equipped with a magnetic stirrer (length 50 mm), 54.2 g of ABu (423 mmol), 23.2 g of MMA (232 mmol), 0 8 g of BDA crosslinking agent (4 mmol), 17 g of a 10% by weight aqueous solution of sodium dodecyl sulphate (SDS, Aldrich). The medium is stirred at 600 rpm until emulsification is for at least 5 minutes.

Preparation E (solar filter: Parsol® MCX):

In a flat-bottomed glass container (inside diameter 55 mm) equipped with a magnetic stirrer (length 50 mm) and protected from light by an aluminum foil, 54.2 g of ABu (423 mmol) are introduced, 23.2 g of MMA (232 mmol), 0.8 g of crosslinking agent BDA (4 mmol), 3.96 g of ethylhexyl methoxycinnamate (Parsol® MCX) and 17 g of a 10% aqueous solution mass of sodium N-lauroylsarcosinate (Schill + Seilacher GmbH, Perlastan L30). The medium is stirred at 600 rpm until emulsification is for at least 5 minutes. Preparation F:

30 g of ABu (10.61 mmol), 3.37 g of MMA (33, 66 mmol), 0.3 g of crosslinking agent DAM (1.53 mmol), 0.49 g of Preparation B (ie 0.136 mmol of SB initiator). The medium is stirred at 600 rpm until emulsification is for at least 5 minutes.

Preparation G:

In a glass dish with a flat bottom (inside diameter 30 mm) equipped with a magnetic stirrer (length 20 mm), 11.71 g of MMA (117 mmol) and 3.82 g of water are introduced. The medium is stirred at 600 rpm until emulsification is for at least 5 minutes. Preparation H (solar filter: Parsol (R) MCX):

In a flat-bottomed glass container (inside diameter 30 mm) equipped with a magnetic stirrer (length 20 mm) and protected from light by an aluminum foil, 11.71 g of MMA (117 mmol) are introduced, 3.61 g of Parsol® MCX and 3.82 g of water. The medium is stirred at 600 rpm until emulsification is for at least 5 minutes.

Example 1 (Comparative) Preparation of an aqueous dispersion of monophasic polymer particles with a surfactant derived from amino acid

In a 100 mm ID round-bottomed reactor equipped with an anchor-shaped glass stirrer, previously degassed with nitrogen, 115 g of Preparation A (ie 2.65 mmol of Na ₂ HPO _{4) are introduced.} ) and then under nitrogen the preparation C.

The reaction temperature is adjusted to 70 ° C using an adjustable height external oil bath and the mixture is stirred at 260 rpm under nitrogen. 10 minutes after the end of the addition, 2.62 g of the preparation B (in moles 0.73 mmol of initiator) are added dropwise at a constant rate for five minutes to the mixture. Then after another ten minutes with stirring, 0.34 g of KPS (1.25 mmol) in solution in 7.7 g of demineralized water are added to the mixture via a peristaltic pump over a period of 2 minutes. After one hour, the reaction mixture is cooled, still stirring. The emulsion obtained (called emulsion 1) is collected in a container as soon as the temperature is below 35 ° C. Example 2 Preparation of an aqueous dispersion of multiphase particles of polymers with an amino acid derived surfactant according to the invention

In the reactor described above, 150 g of emulsion 1 are placed at 70 ° C. under nitrogen and stirring as previously. Preparation F is then added by means of a peristaltic pump over a period of 2 minutes. 0.015 g of KPS (0.055 mmol) dissolved in 0.7 g of demineralized water is then introduced by means of a peristaltic pump over a period of 10 minutes. Stirring is maintained for 60 minutes at 70 ° C., 2.20 g of an aqueous solution of SSF at 1.74% are then added over one minute. in bulk (ie 0.25 mmol of SSF) using a peristaltic pump and, in parallel using two peristaltic pumps, preparation G and 10 g of a 0.5% aqueous solution in mass of ammonium persulfate (ie 0.22 mmol APS) over a period of 15 minutes. After addition, the reactor temperature is maintained at 70 ° C for 30 minutes. After that, the remaining reactive species are quenched by adding a mixture of 0.46 g of an aqueous ammonium persulfate solution (15.61% by weight) and 0.32 g of an aqueous solution of SB (2%). , 8% by weight). The reaction is thus maintained for 30 minutes at 70 ° C. Then, stirring is maintained but the heating is stopped by lowering the oil bath. The emulsion (called emulsion 2) is collected as soon as the temperature is below 35 ° C.

Example 3 (Comparative) Preparation of an aqueous dispersion of multiphasic particles of polymers with sodium dodecyl sulfate surfactant

The procedure of Example 1 is followed but using Preparation D in place of Preparation C. An emulsion 3 is obtained which is converted into emulsion 4 following the procedure of Example 2.

Example 4 Comparison of the Emulsions of Examples 1 to 3

Comparison of particle sizes

Dynamic Light Scattering (DLS) measurements were performed using an ALV / CGS3 goniometer equipped with a multi-τ ALV / LSE 5004 correlator and a He-Ne laser at a wavelength of 632.8 nm. The measurements were made on samples of 10 mm diameter over seven angles of diffusion ranging from 60 ° to 120 ° with an incrementation of 10 °. The system was maintained at 23 ° C. Each sample was prepared as follows: 20 ml of Milli-Q® water, filtered twice on a 0.22 μηι porosity syringe filter are placed in a glass vial. 5 μΐ of emulsion are injected with a micropipette. These samples are then analyzed in sequences of 100 seconds for each angle value, the collected data are then processed by cumulant analysis.

In the emulsion 1 the particles are spherical and have a mean diameter of about 36-38 nm measured by DLS. Emulsion 2 has a pH of between 6 and 7 and the proportion of solids is about 40%. The dispersed polymer particles are spherical and have an average diameter of about 38-42 nanometers measured by DLS. The soft phase of the particles, consisting of a mixture of butyl acrylate and methyl methacrylate, represents approximately 80% of the total weight of the particles and the hard phase, consisting of methyl methacrylate, represents approximately 20% of the total weight of the particles. total weight of the particles.

In the emulsion 4 the particles are spherical and have an average diameter of about 47-49 nm measured by DLS.

Comparison of the mechanical properties of the thick films obtained with emulsion 1 (comparative), emulsion 2 (according to the invention) and emulsion 4 (comparative)

Films of thickness about 0.7 mm are obtained by evaporating an emulsion column 2 of height about 2 mm in a Teflon mold. DIN 53504S3A dumbbells (useful length 12 mm, width 2 mm) corresponding to the ISO 527-3 standard are obtained by punching the sheet about 0.7 mm thick with a punch. room.

The mechanical measurements were carried out at a pulling speed of 10 mm / min using an Instron tensile machine equipped with a force sensor of 500 N and gave the following results: From rectangular samples cut 10 mm x 25 mm in the same film, dynamic mechanical analysis (AMD) measurements are carried out using a DMA 2980 analyzer (TA instruments) in the tension geometry of films by applying a -voltage of 0.01 N and operating at 1 Hz. The values of Tg are the temperatures at which the dissipation factor, tan (delta) passes through a maximum. These values are measured at first heating at 3 ° C / min on unheated films.

The films obtained with emulsion 1 have the following characteristics: - Stress at break: 0.25 MPa

The films obtained with emulsion 2 have the following characteristics:

- Elongational elastic module: 48 MPa

- Plastic deformation threshold: 2.6 MPa - Stress at break: 3.7 MPa

- Nominal deformation at break: 250%

- The strain measurement by video extensometry has shown that the deformation at break is greater than 150% The films obtained with emulsion 4 have the following characteristics:

- Breaking stress: 0.85 MPa

The mechanical measurements made on the films obtained with the emulsion 1 show that the films break for a lower stress, of the order of 0.25 MPa, than for the films obtained with the emulsion 2 according to the invention. In addition, for the films obtained with emulsion 1, plastic deformation is observed even for low applied stresses.

This example shows that films made from monophasic particles (emulsion 1) have lower mechanical properties than films obtained from particles of multiphasic structure according to the invention (emulsion 2). The mechanical measurements made on the films obtained with the emulsion 4 show that the films break for a lower stress, of the order of 0.85 MPa, than for the films obtained with the emulsion 2 according to the invention. In addition, for the films obtained with emulsion 4, plastic deformation is observed even for low applied stresses. This example also shows that films made from multiphase particles have superior mechanical properties when using a derivative amino acid such as sodium N-lauroylsarcosinate as surfactant rather than SDS as in the prior art.

Example 5: Incorporation of active after polymerization (free in solution).

A sample of 8 g of emulsion 2 (Example 2) is centrifuged at 14,000 rpm (r = 0.08 m), ie a radial acceleration of 17500 g for 1 hour at 40 ° C. The pellet is stored, the supernatant is removed and replaced with 16.11 ml of ethanol and 9.7 microliters of a 0.07 M solution of Parsol® MCX (ethylhexyl methoxycinnamate) in ethanol, an initial concentration of 43%. , 3 micromoles / liter. After standing for 24 hours in the dark, the emulsion is again centrifuged under the same conditions. The analysis of the supernatant by ultraviolet spectrometry gives, at 308 nm, an absorbance of 0.325. At the same wavelength, standard solutions of 2.78 micromoles / liter and 4.48 micromoles / liter of Parsol® MCX in ethanol have absorbances of 0.317 and 0.345 respectively.

Example 6: Incorporation of active in the internal phase of the polymer particles.

The procedure of Example 1 is followed except that Preparation E is used in place of Preparation C and the reactor and flasks are protected from light by aluminum foil. The emulsion obtained is then converted according to the procedure of Example 2, protecting the reactor and the flasks with aluminum foil.

The particle size of the emulsion obtained, measured by light scattering (DLS), is about 36-38 nm.

Example 7 Incorporation of Active in the External Phase of the Polymer Particles The procedure of Example 2 is followed except that Preparation H is used in place of Preparation G and the reactor and flasks are protected from light by aluminum foil. The final size of the particles measured by light scattering (DLS) is about 40-44 nm.

A film is made from this emulsion under conditions identical to those of Example 4, but with the exclusion of light. The values of Tg measured in the same way as in Example 4 are:

The mechanical properties, measured in the same way as in Example 4 give the following results:

Elongational elastic module: 10 MPa Plastic deformation threshold: 1 MPa

Stress at break: 2.1 MPa

Nominal deformation at break: 250%

EXAMPLE 8 Comparative Measurement of the Transmittance of the Films Formed from the Emulsions of Examples 2 and 7 The transmittance of the film obtained in Example 7 is measured in the visible at 530 nm and in the UVB at 308 nm using a Jasco V-530 spectrometer by placing the film as close as possible to the detector. The same measurement is made on a control film free of sunscreen, made according to Example 2.

The following results are obtained:

Example 9 Application of the Filmoene Composition According to the Invention

On a clean and dry skin surface of 3 cm ² , the film-forming composition of Example 2 is applied with a brush in a single layer of 150 μm.

After two minutes, the water is completely evaporated and the skin is covered with a film that is elastic, adheres to the skin for several hours, has no superficial tights and is water-resistant, especially to several hand washes.

Claims

An aqueous dispersion of multiphase particles of polymers in which the polymer particles comprise at least two distinct phases:

a first phase formed by a soft polymer Pi having a glass transition temperature (Tg less than 20 ° C., preferably less than 20 ° C.

5 ° C, more preferably below 0 ° C,

a second phase formed by a hard polymer P ₂ having a glass transition temperature (Tg ₂ ) greater than 60 ° C., preferably greater than 70 ° C., more preferably greater than 80 ° C.,

said dispersion comprising a surfactant selected from amino acid derivatives and wherein the polymer Pi is formed by polymerization in the presence of a crosslinking agent.

2. Aqueous dispersion according to claim 1, characterized in that the phase formed by the soft polymer Pi is the internal phase of the particle and the phase formed by the hard polymer P ₂ is the outer phase of the particle.

3. Aqueous dispersion according to any one of the preceding claims, characterized in that the multiphase particles of polymers are substantially spherical and have a diameter of between 15 and 300 nanometers, preferably between 30 and 100 nanometers.

4. Aqueous dispersion according to any one of the preceding claims, characterized in that the polymer Pi represents 60 to 90% by weight of the particles and the polymer P ₂ represents 10 to 40% by weight of the particles.

5. An aqueous dispersion according to any one of the preceding claims, characterized in that the polymer Pi comprises:

- 90 to 99.5%, preferably 93 to 99%, more preferably 95 to 98% by weight of units obtained by polymerization of at least one monomer selected from the group (I) consisting of alkyl (Ci-Cie) esters of (meth) acrylic acid such as methyl (meth) acrylate, ethyl (meth) acrylate and butyl (meth) acrylate, hydroxyalkyl esters of (meth) acrylic acid, vinyl esters of linear or branched carboxylic acids such as vinyl acetate and vinyl stearate, styrene, alkylstyrenes such as methylstyrene, haloalkylstyrenes such as chloromethylstyrene, (meth) acrylamide, acrylonitrile, vinyl chloride, (meth) acrylic acids and their derivatives such as anhydrides, monomers containing acids or basic such as itaconic acid, fumaric acid, crotonic acid, maleic acid, silane (meth) acrylic or vinyl monomers such as methacryloxypropyl triethoxy or triisopropoxysilane, the monomers containing acetoacetoxy groups, such as acetoacetoxyethyl (meth) acrylate, and mixtures thereof; and

0.5 to 10%, preferably 1 to 7%, more preferably 2 to 5% by weight of units obtained by polymerization of a crosslinking agent.

6. An aqueous dispersion according to claim 5, characterized in that the crosslinking agent is chosen from the group (II) consisting of allylic or (C _1-6 ) alkyl esters of monocarboxylic or dicarboxylic acids, such as allyl acrylate, allyl methacrylate, diallyl maleate or phthalate and dimethyl maleate, conjugated dienes such as butadiene and isoprene, polyol poly (meth) acrylates such as ethylene glycol dimethyl acrylate or triethylene glycol, 1,3-or 1,4-butyleneglycol dimethylacrylate, 1,4-butanediol diacrylate and pentaerythritol tetraacrylate, trimethylolpropane triacrylate, polyvinylbenzenes such as divinylbenzene or trivinylbenzene and polyallyl derivatives such as triallyl cyanurate, triallyl isocyanurate and triallyl trimesate, and mixtures thereof.

7. Aqueous dispersion according to any one of the preceding claims characterized in that the polymer P ₂ comprises 95 to 99.5%, preferably 97 to 99%, more preferably 100% by weight of units obtained by polymerization of at least one monomer chosen in group (I) as defined in claim 5.

8. An aqueous dispersion according to claim 5, characterized in that the monomers of the group (I) of the polymer Pi are chosen from butyl acrylate and methyl methacrylate, and mixtures thereof.

9. An aqueous dispersion according to claim 6, characterized in that the crosslinking agents of the group (II) of the polymer Pi are chosen from diallyl maleate, dimethylmaleate and 1,4-butanediol diacrylate, and mixtures thereof.

10. An aqueous dispersion according to claim 7, characterized in that the monomer of the group (I) of the polymer P ₂ is methyl methacrylate.

11. An aqueous dispersion according to any one of the preceding claims, characterized in that the polymer P ₂ contains at least 91%, preferably at least 95%, and more preferably still 100% by weight of units obtained by polymerization of monomers. hydrophobic.

12. An aqueous dispersion according to any one of the preceding claims, characterized in that the surfactant derived from amino acids is selected from sarcosinic acid derivatives and glutamic acid derivatives.

13. An aqueous dispersion according to claim 12, characterized in that the surfactant derived from amino acids is selected from sodium / V-lauroylglutamate, disodium V / cocoylglutamate, sodium / V-cocoylglutamate, / V sodium lauroylsarcosinate, sodium V-myristoylsarcosinate, sodium V-cocoylsarcosinate, sodium N-oleoylsarcosinate, ammonium N-lauroyl sarcosinate, and mixtures thereof, preferably lauroyl sarcosinate; sodium, sodium / V-myristoylsarcosinate and sodium / V-lauroylglutamate, preferably sodium V-lauroylsarcosinate.

14. An aqueous dispersion according to any one of the preceding claims, characterized in that the concentration of the surfactant is between 0.1 and 5% by weight, relative to the weight of solids of the aqueous dispersion, preferably between 0, 4 and 5% by weight, and even more preferably between 0.7 and 2% by weight.

15. Aqueous dispersion according to any one of the preceding claims, characterized in that the pH of the aqueous dispersion is greater than one unit above the pKa of the surfactant used.

16. Aqueous dispersion according to any one of the preceding claims, characterized in that it comprises an active agent chosen from anti ^¬ bacterial agents, antiseptics, anti-viral, antifungal agents, anti-pain, anti inflammatory agents, the agents promoting healing, the moisturizing agents, the depigmenting agents, keratolytic agents, restructuring agents, anesthetics and sunscreens.

17. An aqueous dispersion according to claim 16, characterized in that the active agent is incorporated in the inner phase or in the outer phase of the multiphase particles of polymers.

18. A film-forming composition characterized in that it comprises, in a physiologically acceptable medium, an aqueous dispersion of multiphase particles of polymers according to any one of claims 1 to 17.

19. Film-forming composition according to claim 18, characterized in that it comprises a pharmaceutical agent chosen from antibacterial agents, antiseptics, anti-virals, antifungal agents, anti-pain agents, anti-inflammatory agents, anti-inflammatory agents and anti-inflammatory agents. scarring, moisturizing agents, depigmenting agents, keratolytic agents, restructuring agents, anesthetics and sunscreens.

20. Film characterized in that it has at least two different Tg, said film comprising multiphase particles of polymers and a surfactant, wherein the polymer particles comprise at least two distinct phases:

21. Use of a film according to claim 20 for protecting skin surfaces, mucous membranes, wounds, lesions and / or skin conditions.