FR2911504A1 - COSMETIC O / W EMULSION CONTAINING LIPOPHILIC UV FILTER, POLAR OIL AND COPOLYMER DIBLOC (POLYSTYRENE) -BLOCK-POLY (ACRYLIC ACID-STAT ACRYLATE, C1-C4 ALKYL) - Google Patents

Abstract

The present invention relates to an oil-in-water emulsion comprising in a physiologically acceptable medium: a) at least one continuous aqueous phase, b) at least one fatty phase dispersed in said aqueous phase comprising at least one polar oil, c) at least one a lipophilic organic UV filter) and optionally at least one inorganic insoluble UV filter and / or an insoluble organic UV filter, e) at least one diblock copolymer (block A) - (blockB) in which block A comprises at least units styrene derivative; block B comprises at least (a) units derived from acrylic acid in acid or salified form and (b) at least units derived from a C 1 -C 4 alkyl acrylate. also relates to the use of at least one diblock copolymer as defined above in an oil-in-water fluid emulsion comprising a) at least at least one fatty phase comprising at least one polar oil, b) at least one organic UV filter l ipophile and possibly c) at least one inorganic UV filter and / or at least one insoluble organic filter, for the purpose of improving the cosmetic properties and / or improving the stability of said emulsion and / or for the purpose of increasing the sun protection factor (SPF) and / or to improve the water retention of the photoprotective power.

Description

COSMETIC O / W EMULSION CONTAINING LIPOPHILIC UV FILTER, OIL

  The present application relates to an oil-in-water cosmetic emulsion comprising in a physiologically acceptable medium: a) at least one of at least one of at least one of at least one embodiment of the present invention. a continuous aqueous phase; b) at least one fatty phase dispersed in said aqueous phase comprising at least one polar oil; c) at least one lipophilic organic UV filter; d) and optionally at least one inorganic insoluble UV filter and / or an insoluble organic UV filter; e) at least at least one diblock copolymer (block A) - (blockB) in which - block A comprises at least units derived from styrene; - Block B comprises at least (a) units derived from acrylic acid in acid or salified form and (b) at least units derived from a C 1 -C 4 alkyl acrylate.

  It is well known that the luminous radiations of wavelengths between 280 nm and 400 nm allow the browning of the human epidermis and that the wavelength rays between 280 and 320 nm, known under the name of UV-B, cause erythema and skin burns that can affect the development of natural tanning; this UV-B radiation must therefore be filtered.

  It is also known that UV-A rays of wavelengths between 320 and 400 nm, which cause browning of the skin, are capable of inducing an alteration thereof, especially in the case of a skin sensitive or skin continuously exposed to solar radiation. UV-A rays cause in particular a loss of elasticity of the skin and the appearance of wrinkles leading to premature aging. They promote the triggering of the erythematous reaction or amplify this reaction in some subjects and may even be the cause of phototoxic or allergic photo reactions. It is therefore desirable to also filter the UV-A radiation.

  Numerous cosmetic compositions intended for the photoprotection of the skin have been proposed to date.

  Among these products, the fluid oil-in-water emulsions are, in general, more appreciated by the consumer than the thicker emulsions, in particular because of their pleasant feel and their easy to apply presentation. These compositions intended for the photoprotection of the skin consist of an aqueous dispersant continuous phase and an oily dispersed discontinuous phase which contain, at various concentrations, one or more conventional organic lipophilic and / or hydrophilic filters capable of selectively absorb UV radiation. Lipophilic organic filters need to be solubilized in polar oils. The proportion of polar oil of the discontinuous internal phase of the emulsion will thus be all the more important that the solubility of the filtering compounds will be low and / or that their concentration will be high.

  Moreover, the use in these compositions of metallic oxide pigments is particularly interesting because this type of inorganic UV filters makes it possible to obtain high protection indices in association with conventional organic UV screening agents, in particular lipophilic ones.

  Micronized insoluble organic UV filters with a mean particle size ranging from 10 nm to 2 μm are known in the prior art and have the advantage of being more effective than their soluble counterparts comprising the same chromophore group at an equivalent rate. This type of UV filters is in particular described in patent applications EP746305 and EP8405395.

  The production of stable emulsions containing polar oils and lipophilic organic UV filters poses numerous difficulties, particularly when it comes to developing a strong protection and therefore introducing significant amounts of lipophilic organic filters and oils. polar solubilizing. This results in an instability of the composition which thus adversely affects the quality of the product and the effectiveness of the protection. In general, this instability is remedied by the use of thickeners introduced into the external phase of the composition.

  These difficulties of stabilization of the emulsions containing polar oils and lipophilic organic UV filters are accentuated as soon as it is necessary to obtain compositions of very low viscosity, since the content of the thickener of the formula is then deliberately limited. it is possible to maintain the viscosity at the desired level, which has the effect of further aggravating the phenomena of instability.

  One way to obtain low viscosity emulsions is to use extremely powerful stirring means such as high pressure homogenizers. The manufacture of emulsions with such equipment makes it possible to obtain very fluid O / W dispersions, in particular with polar oils, but this process limits the use of the filtration means which are available to the formulator and in particular the introduction in addition to filters in the form of insoluble particles during manufacture.

  These insoluble filters are not compatible with these devices, either because of the size of the particles which can clog the orifices of these equipments, or because of the abrasive or even destructive nature of the hardness pigments important as the titanium introduced at high pressure into such equipment. In doing so we are limited in assets usable to develop high protection indices.

  Thus, there is still a need to be able to produce antisolar compositions in the form of a low viscosity oil-in-water emulsion containing lipophilic organic UV filters and polar oils for solubilizing them which are stable over time and provide effective sun protection. , while having cosmetic performance of lightness and ease of application related to the fluidity; and without the need to resort to extremely powerful stirring means such as high pressure homogenizers. Such compositions must be able to additionally contain insoluble organic or inorganic UV filters without the disadvantages mentioned above.

  The Applicant has surprisingly and unexpectedly discovered that this objective could be achieved by using at least one linear diblock copolymer (block A) - (blockB) in which - block A comprises at least units derived from styrene; - Block B comprises at least (a) units derived from acrylic acid in acid or salified form and (b) at least units derived from a C 1 -C 4 alkyl acrylate.

  These copolymers thus make it possible to obtain very fluid oil-in-water emulsions containing both lipophilic organic UV filters and polar oils without a high pressure homogenizer, ie with conventional rotor-stator type stirring means. .

  It is therefore possible to use a wide range of lipophilic organic UV filters solubilized by polar oils. In addition, insoluble filters can be introduced at any time during manufacture without damage to the stirring equipment and without having to go through a pre-dispersion or a concentrated emulsion.

  The compositions thus obtained not only make it possible to obtain sunscreen compositions whose cosmetic performance is greater than that generally obtained with a conventional oil-in-water emulsion, but also exhibit a photo-protective efficacy (increase in the sun protection factor (SPF) ) and improved water retention.

  Thus, the present invention relates to an oil-in-water cosmetic emulsion comprising in a physiologically acceptable medium: a) at least one continuous aqueous phase; b) at least one fatty phase dispersed in said aqueous phase comprising at least one polar oil; c) at least one lipophilic organic UV filter; d) at least one diblock copolymer (block A) - (blockB) in which - block A comprises at least units derived from styrene; - Block B comprises at least (a) units derived from acrylic acid in acid or salified form and (b) at least units derived from a C 1 -C 4 alkyl acrylate. The present invention also relates to an emulsion as defined above additionally containing at least one insoluble organic or inorganic UV filter.

  The subject of the present invention is also the cosmetic use of at least one diblock linear copolymer as defined above in an oil-in-water emulsion, in particular a fluid, comprising in a physiologically acceptable medium: a) at least one fatty phase dispersed in said aqueous phase comprising at least one polar oil, b) at least one lipophilic organic filter and optionally additionally at least one insoluble organic or inorganic UV filter, for the purpose of improving the cosmetic properties and / or improving the stability of the said composition and / or in order to increase the sun protection factor (SPF) and / or to improve the water retention of the photoprotective power. Definitions Physiologically acceptable medium means a non-toxic medium that can be applied to the skin, the lips, the hair, the eyelashes, the eyebrows and the nails. The composition of the invention may constitute in particular a cosmetic or dermatological composition.

  The term "UV-lipophilic filter" is understood to mean any UV radiation filtering agent capable of being completely dissolved in the molecular state in a fatty phase of the emulsion or else to be solubilized in colloidal form (for example in micellar form) in a fatty phase.

  By polar oil is meant any oil whose interfacial oil / water tension measured at 25 C with the aid of a Krüss model K12 tensiometer equipped with a Nouy 50 type ring is less than 45 mN.m -1. The values are read when the standard deviation between the last three measurements becomes less than 0.01. They have been corrected by the Harkins-Jordans factor, which takes into account the characteristics of the studied liquid (density) and the ring (geometry).

  The term "fluid emulsion" means any emulsion that does not appear in a solid form. Its viscosity can be measured using a Rhéomat 180 viscometer at 25 ° C. at a rotation speed of 200 RPM after 30 seconds of rotation, with a measuring body 2, 3 or 4 and is preferably less than or equal to 20. Pa.s, more preferably less than 5 Pa.s, even more preferably less than or equal to 2 Pa.s, and more particularly less than or equal to 0.5 Pa.s.

  In the present application the term diblock copolymer refers to a block copolymer architecture consisting of two blocks, and having substantially no other block sequence.

  In the present application, the unit derived from a monomer denotes a unit that can be obtained directly from said monomer by polymerization. Thus, for example, a unit derived from an acrylic or methacrylic acid ester does not cover a unit of formula -CH 2 -CH (COOH) -, or -CH 2 -C (CH 3) (COOH) -, obtained for example by polymerizing an acrylic or methacrylic acid ester and then hydrolyzing. Thus, the unit terminology derived from a monomer is only relative to the final constitution of the polymer and is independent of the polymerization process used to synthesize the polymer.

  In the present application, the ratio by weight between the blocks corresponds to the ratio between the masses of the monomers (or mixtures of monomers) used for the preparation of the blocks (taking into account the mass variations related to a subsequent hydrolysis). The proportions by weight of the blocks are the proportions relative to the total diblock copolymer, and correspond to the proportions by weight of the monomers (or mixtures of monomers) used for the preparation of the blocks, with respect to all the monomers used to prepare the diblock copolymer (taking into account mass variations related to subsequent hydrolysis).

  In the present application, the masses and ratios bound to the blocks are indicated in acid equivalents (units derived from acrylic acid in acid form, as opposed to a salified form of sodium acrylate type).

  In the present application, the term "hydrophilic monomer" is understood to mean a monomer which has affinity for water, and which typically is not capable of forming a two-phase macroscopic solution in distilled water at 25 ° C., at a concentration of 1% by weight.

  In the present application, the molar mass MA of a mixture of monomers A1 and A2 of respective molar masses MAI and MA2, present in respective numbers of nAl and nA2, denotes the number-average molecular weight MA = MAI nAl / (nAl + nA2 ) + MA2 nA2 / (nAl + nA2). The molar mass of a mixture of units in a macromolecular chain or part of a macromolecular chain (a block for example) is similarly defined, with the molar masses of each of the units and the number of each of the units.

  In the present application, the measured average molecular weight of a first block or of a copolymer denotes the number-average molecular weight in polystyrene equivalents of a block or of a copolymer, measured by steric exclusion chromatography (SEC). in THF with calibration using polystyrene standards. The average measured molecular weight of a single block in an n-block copolymer is defined as the difference between the measured average molecular weight of the copolymer and the measured average molecular weight of the (n-1) block copolymer from which it is prepared. For the sake of simplicity, it is common to express the average molecular masses of the blocks in "theoretical" or "target" average molecular weights, considering a complete and perfectly controlled polymerization. In this case, a macromolecular chain is formed by the transfer function of a transfer agent; to obtain the molecular mass it suffices to multiply the average molar mass of the units of a block by the number of units per block (quantity in number of monomers per quantity in number of transfer agent). In these calculations, the differences induced by small amounts of co-momoners such as methacrylic acid can be neglected. The theoretical or target average molecular masses of the B block are expressed by considering a total hydrolysis (the masses are expressed with the fiction of a hydrolysis rate of 1). The theoretical average molecular weight Mbloc of a block is typically calculated according to the following formula: ## EQU1 ## The "theoretical" or "target" average molecular weight of a block copolymer is considered as the addition of the average molecular weights of each of the blocks, considering a total hydrolysis (the masses are expressed with the fiction of a hydrolysis rate of 1), if such hydrolysis has been carried out.

  In the present application, the target or theoretical total mass of a block 30 is defined as the mass of the macromolecular chain by considering a complete and perfectly controlled polymerization. To obtain the total mass it is sufficient to multiply the molar mass of a unit of a block by the number per block of this unit and to add the masses thus obtained for each type of unit in the block. The differences induced by small amounts of co-momoners such as methacrylic acid can be ignored in these calculations. The theoretical or target total masses of the B block are expressed considering the effect of a partial hydrolysis (for this descriptor the fiction of a degree of hydrolysis of 1) is not used, if such hydrolysis has been performed.

  In the present application, the degree of hydrolysis T is defined as the ratio between the number of units derived from acrylic acid or a salt of acrylic acid, and the number of units derived from the alkyl acrylate. C1-C4, present in a copolymer before hydrolysis. The number of units derived from the C 1 -C 4 alkyl acrylate is considered to be equal to the amount by number of alkyl acrylate monomer used for the preparation of the copolymer before hydrolysis. The number of units derived from acrylic acid or from an acrylic acid salt can be determined by any known method, in particular by acidobasic potentiometric titration of the number of COONa groups using a strong acid, for example using hydrochloric acid.

  In the present application, the term "transfer agent" is understood to mean an agent capable of inducing a controlled radical polymerization in the presence of unsaturated monomers and possibly of a source of free radicals. Mbloc i nprecursor where Mi is the molar mass of a monomer i, ni is the number of moles of the monomer i, nprecursor is the number of moles of functions to which the macromolecular chain of the block will be bound. The functions can come from a transfer agent (or a transfer group) or an initiator, a previous block etc. If it is a preceding block, the number of moles can be considered as the number of moles of a compound to which the macromolecular chain of said previous block has been linked, for example a transfer agent (or a group of transfer) or an initiator. In practice, the theoretical average molecular weights are calculated from the number of moles of monomers introduced and the number of moles of introduced precursor.

copolymer

  The diblock copolymers according to the invention are advantageously linear. Block B comprises two different units. They will generally be randomly distributed in block B. Block B is then a statistical block.

  More preferably the proportion by weight of the block B with respect to the copolymer is greater than or equal to 50%.

  The diblock copolymers in accordance with the invention are more particularly characterized by the fact that they are diblock linear copolymers (block A) - (block B) in which: block A comprises at least 90% by weight of units derived from styrene based on the total weight of block A; block B is a statistical block comprising, based on the total weight of block B: (i) from 34 to 95% by weight of units derived from acrylic acid in acid form or in salified form; (ii) from 5 to 66% by weight of units derived from C1-C4 alkyl acrylate.

  It is mentioned that block A may comprise up to 10% of units other than units derived from styrene relative to the total weight of block A. It is mentioned that block B may comprise units other than units derived from acrylic acid and the units of the alkyl acrylate. Such units are taken into account in the composition of block B (proportion of different units), the total units being 100%.

  It is mentioned that the ratio by weight between the units derived from acrylic acid and the units derived from the C 1 -C 4 alkyl acrylate is preferably between 34/66 and 95/5, preferably between 64/36 and 75/25.

  The C1-C4 alkyl acrylate is preferably an alkyl acrylate hydrolyzable to acrylic acid. The units derived from the C1-C4 alkyl acrylate are preferably derived from an alkyl acrylate hydrolyzable to acrylic acid. Thus, by a preferred method, units derived from acrylic acid may be generated from units derived from alkyl acrylate, upon partial hydrolysis.

  C1-C4 alkyl acrylates include, in particular, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, acrylate, and the like. tert. In particular, ethyl acrylate and t-butyl acrylate are known to be easily hydrolysed.

  The C 1 -C 4 alkyl acrylate of the copolymer of the invention is advantageously ethyl acrylate (often denoted EA or AE or AEt).

  Block A and / or block B may comprise up to 10% by weight (in particular from 0.1% to 5% by weight), preferably comprising up to 5% by weight (especially from 0.1% to 5% by weight, of an additional hydrophilic comonomer, ionic or nonionic relative to the total weight of block A or block B containing said hydrophilic comonomer.

  Among the additional hydrophilic comonomers, ionic or nonionic, there may be mentioned for example acrylamide, hydroxyethyl (meth) acrylate, methacrylic acid (AMA) in acid or salified form. It is more particularly preferred to use methacrylic acid in acid or salified form. Block A can also comprise, as additional hydrophilic monomer, acrylic acid in acidic or salified form.

  Preferably, the copolymer does not comprise a boronic function, in acid or salified form. A first family of diblock copolymers according to the invention which are particularly preferred consists of diblock copolymers (block A) - (block B) of the type (1) in which the proportion by weight of block B with respect to the copolymer is between 50 and 85%.

  Among these diblock copolymers of type (1), there are two types of preferred copolymers: - Type (1 a) those in which the proportion by weight of block B is greater than or equal to 75% and preferably between 75 and 85%. - Type (1b): those where the proportion by weight of the block B relative to the copolymer is less than 75% and preferably between 50 and 75% by weight.

  A second family of diblock copolymers according to the particularly preferred invention consists of diblock copolymers (block A) - (block B) of the type (2) in which the proportion by weight of block B with respect to the copolymer is greater than or equal to at 85%.

  Among these diblock copolymers of type (2), two types of copolymers are advantageously distinguished: - Type (2a): where the proportion by weight of block B with respect to the copolymer is greater than or equal to 87%, in particular greater than or equal to 87 % and less than 94%. - Type (2b): where the proportion by weight of the block B relative to the copolymer is greater than or equal to 94%, in particular ranging from 94% to 97%.

  Among these diblock copolymers of type (2a), there are advantageously two types of copolymers: - Type (2a1): where in block B: - the proportion by weight of units derived from acrylic acid in free or salified form is included between 64% (obtained for example by a hydrolysis at a rate of T = 0.7) and 75% (obtained for example by a hydrolysis at a rate of T = 0.8), and - the proportion of the weight of units derived from the C 1 -C 4 alkyl acrylate is between 25% (obtained for example by a hydrolysis at a rate of T = 0.8) and 36% (obtained for example by a d hydrolysis at a rate of T = 0.7).

  - Type (2a2): where in block B: the proportion by weight of units derived from acrylic acid in free or salified form is between 75% (obtained for example by a hydrolysis at a rate of T = 0.8) and 95% (obtained for example by a hydrolysis at a rate of T = 0.96), and the proportion by weight of units derived from the C 1 -C 4 alkyl acrylate is included between 5% (obtained for example by a hydrolysis at a rate of T = 0.96) and 25% (obtained for example by a hydrolysis at a rate of T = 0.8).

  According to one particular embodiment of the invention, a mixture of at least one diblock copolymer of the type (1) and at least one diblock copolymer of the type (2) and even more particularly a mixture of at least one diblock copolymer will be used in the emulsions. minus a diblock copolymer of type (Ia) (BOL 20) and at least one diblock copolymer of type (2b) (BOL 55) as defined above.

  The copolymer of the invention may in particular be presented in one of the following ways: in solid or dry form, or in the form of a fluid concentrated ingredient comprising a vector, in a concentration preferably of greater than 8% by weight.

  If it is in the form of a fluid concentrated ingredient comprising a vector, in a concentration preferably of greater than 8% by weight, the vector may in particular comprise water and / or an alcohol solvent, the alcohol being preferably chosen from ethanol or isopropanol. In particular, the alcohol can contribute to fluidizing the copolymer and to making its industrial use easier. The vector may be water or a mixture of more than 50% by weight of water and less than 50% by weight of alcohol. The copolymer concentration may be at least 25% by weight, and preferably at most 75% by weight.

  Process The copolymer of the invention may be prepared by any suitable method, comprising a polymerization phase. The copolymer according to the invention can be obtained by any known method, whether by radical polymerization, controlled or not, by ring-opening polymerization (in particular anionic or cationic), by anionic or cationic polymerization, or by chemical modification of the polymer. a polymer.

  An advantageous process comprises the following steps: step I): a diblock copolymer (block A) - (block B ') is prepared, or - a triblock copolymer or architecture star (core) - [(block A) - (block B ')] x where (core) - [(block B') - (block A)] x or x is an average number greater than or equal to 2, where - block A comprises units derived from styrene, and the block B 'comprises the units derived from a C 1 -C 4 alkyl acrylate, step I') optionally, for a triblock or star copolymer, the bonds (core) - (block B ') or (core) are broken ) - (block A), so as to obtain a diblock copolymer (block A) - (block B '),

  step II) the block B 'is hydrolyzed to a block B to obtain the diblock copolymer (block A) - (block B), the hydrolysis inducing, if appropriate, for a triblock or star copolymer, a breakage of the bonds (core) - (block B ') or (core) - (block A), so as to obtain a diblock copolymer (block A) - (block B).

  The method may further optionally include a step III) during and / or after step II), deactivating transfer groups carried by macromolecular chains and / or purifying the diblock copolymer (block A) - ( Block B) and / or destruction of hydrolysis and / or deactivation byproducts.

  The polymerization process as described above, applied to the preparation of copolymers resembling those of the invention, is described in particular in WO 01/16187.

  It is mentioned that the terminologies of the type (block A) - (block B ') do not, however, exclude the presence of useful chemical groups (transfer groups or residues) for the polymerization, in particular at the ends of chains or at the center of the chains . Thus, the diblock copolymer can actually have a formula of the R- (block A) - (block B ') - X group where X is a transfer group (for example X is a transfer group of formula ùSCS-Z or a residue such a group).

  Step I) is a polymerization step. Step I ') is optional and may optionally be applied if the copolymer prepared in step I) is a triblock or star copolymer. However, if the copolymer prepared in step I) is a triblock or star copolymer, it is possible to break the bonds during a hydrolysis step. If the break can be carried out during the hydrolysis step, then step I ') will not be very useful, and will preferably be omitted. According to an advantageous embodiment, stage I) is carried out by polymerization

  in emulsion in water. The diblock copolymers (block A) - (block B) used in the context of the invention may in particular be obtained as follows

  in step I), a diblock copolymer (block A) - (block B ') is prepared by a process comprising the following intermediate steps la) and lb):

  1a), a first block A is prepared by bringing into contact: - nT moles of a transfer agent comprising a single transfer group - nA moles of styrene or a monomer mixture comprising at least 90% by weight styrene and where nA / nT> 5 and preferably <5000; - and possibly an initiator of free radicals

  1b) a second block B 'is prepared to obtain a diblock copolymer (block A) - (block B'), by bringing into contact: - the block A obtained in the preceding step, - nB moles of an acrylate C1-C4 alkyl or a monomer mixture comprising at least 90% by weight of a C1-C4 alkyl acrylate such that nB / nT> 5 and preferably <5000; and optionally a free radical initiator, during step II) subsequent to stage I), the block B 'is subsequently hydrolysed at a molar T ratio of between 0.4 and 0.96. to obtain said diblock copolymer (block A) - (block B) and - 20000 nA / nT MA + MAA nB / nT 35 - [T MAA nB + (1-T) MB nB] / [MAnA + T MAA nB + ( 1-T) MB nB]? 50% where MA is the molar mass of styrene or monomer mixture comprising styrene used in step 1a), and MB is the molar mass of C1-C4 alkyl acrylate or monomer mixture comprising the C1-C4 alkyl acrylate employed in step 1b).

  The process may further optionally include a step III) during and / or after step II), deactivation of transfer groups carried by macromolecular chains and / or purification of the diblock copolymer (block A) - (Block B) and / or destruction of byproducts of hydrolysis and / or deactivation.

  According to an advantageous embodiment, steps la) and lb) of step I) are carried out by emulsion polymerization in water.

  The degree of hydrolysis T can advantageously be between 0.7 and 0.8; preferably T is 0.75. Transfer agents useful for the implementation of the process (in step I)) are known to those skilled in the art and include especially compounds comprising a transfer group -S-CS-, for the implementation of polymerization processes known as RAFT and / or MADIX. Such methods and agents are detailed below.

  During step I) described above, the preparation of a first block can be carried out starting from monomers or from a mixture of monomers, initiators and / or agents promoting the control of the polymerization ( transfer agents with groups -S-CS-, nitroxides etc ...), then the growth of a second block on the first block to obtain a diblock copolymer with monomers different from those used for the preparation of the previous block, and optionally with addition of initiators and / or agents promoting the control of the polymerization. These methods of preparing block copolymers are known to those skilled in the art. It is mentioned that the copolymer may have, at the end of the chain, a transfer group or a residue of a transfer group, for example a group comprising a ûS-CS- group (for example derived from a Xanthate or a dithioester). or a residue of such a group.

  In step II), the units derived from the hydrolyzable monomers of block B 'are hydrolyzed partially to form a block B comprising units derived from acrylic acid or a salt (hydrolysed units), and units derived from the monomer alkyl acrylate (unhydrolyzed units). These two types of units are statistically distributed in block B; it can therefore be considered that block B is a block in the form of a random copolymer comprising units derived from alkyl acrylate and units derived from acrylic acid or from an acrylic acid salt. Naturally, the block B may comprise other units, in minimal amounts, if a monomer mixture is used during the implementation of step 1b).

  Block A includes units derived from styrene. Block A can be obtained from a monomer mixture comprising at least 90% by weight, preferably at least 95%, styrene ("St") and a comonomer or several hydrophilic comonomers (s). Block A may thus be a random copolymer comprising at least 90% (in particular from 90% to 99.9% by weight), preferably at least 95% by weight (especially from 95% to 99.9% by weight). units derived from styrene, and up to 10% by weight (in particular from 0.1% to 10% by weight), preferably up to 5% by weight (in particular from 0.1% to 5% by weight) other units derived from hydrophilic co-monomer (s).

  Block B 'comprises units derived from a C 1 -C 4 alkyl acrylate. Block B 'can be obtained from a monomer mixture comprising at least 90% (in particular from 90% to 99.9%); preferably at least 95% (especially 95% to 99.9%) by weight of a C 1 -C 4 alkyl acrylate and one or more hydrophilic comonomer (s).

  Block B 'may thus be a random copolymer comprising at least 90% (in particular from 90% to 99.9%), preferably at least 95% (in particular from 95% to 99.9%), by weight of units derived from C1-C4 alkyl and up to 10% (especially from 0.1% to 10%), preferably up to 5% (in particular from 0.1% to 5%), by weight of other units, derived from hydrophilic co-monomer (s).

  Block B obtained from block B 'after hydrolysis, comprises units derived from the hydrolyzable C1-C4 alkyl acrylate, units derived from acrylic acid or a salt, and optionally units derived from a comonomer hydrophilic used during step lb) of growth of the block B ', for example units derived from methacrylic acid. Methacrylic acid is generally present in block B as a salt. This form generally results from the conditions for carrying out the hydrolysis and the reagents used. It is usually an alkali metal salt such as sodium or potassium. Therefore, block B generally comprises units derived from acrylic acid in the form of sodium or potassium acrylate. Among the hydrophilic comonomers which may be useful for the preparation of block A and / or block B mention is made of the hydrophilic comonomers capable of stabilizing a monomer emulsion and / or of stabilizing the polymer obtained by emulsion polymerization. Mention may in particular be made of ionic or nonionic hydrophilic comonomers such as acrylamide, hydroxyethyl (meth) acrylate, methacrylic acid (AMA) and their salts. It is preferred to use methacrylic acid or its salts. Methacrylic acid is not sensitive to hydrolysis. It can, however, be salified during hydrolysis. For the preparation of the block A, it is also possible to use acrylic acid and its salts as hydrophilic comonomer.

  Among the hydrolyzable C1-C4 alkyl acrylates, mention is made in particular of ethyl acrylate (EA or AE or AEt).

  According to one particular embodiment, the block A and / or the block B 'or B comprises from 0.1 to 10%, preferably from 0.1 to 5%, by weight of hydrophilic comonomer, in particular the acid methacrylic acid or salified form relative to the total weight of block A, block B 'or block B containing said hydrophilic comonomer.

  Thus, during step la), or may use a monomer mixture comprising at least 90%, preferably at least 95%, by weight of styrene, and up to 10%, preferably up to 5%, by weight of methacrylic acid in acid or salified form.

  In step 1b), or may use a monomer mixture comprising at least 90%, preferably at least 95%, by weight of C 1 -C 4 alkyl acrylate such as ethyl acrylate, and up to 10%, preferably up to 5%, by weight of methacrylic acid in acid or salified form

  Some characteristics of the process for preparing the copolymers of the invention are described below. Step I)

  Preferably, for the polymerization step I), so-called living or controlled radical polymerization methods are used, and particularly preferably controlled or living radical polymerization methods using a transfer agent comprising a group of transfer of formula S-CS-, especially known under the names of RAFT or MADIX.

  By way of examples of so-called living or controlled polymerization processes, it is possible to refer in particular to: the processes of the applications WO 98/58974, WO 00/75207 and WO 01/42312 which implement a controlled radical polymerization by means of Xanthates-type control agents, - controlled radical polymerization process by dithioesters or trithiocarbonates type control agents of the application WO 98/01478, - the radical polymerization process controlled by dithiocarbamate type control agents of the WO 99/31144, the method of controlled radical polymerization by dithiocarbazate type control agents of the application WO 02/26836, 50 - to the radical polymerization process controlled by dithiophosphoroesters type control agents of the application WO 02 / 10223, - the process of the application WO 99/03894 which implements a polymerization in the presence of nitroxide precursors, o the methods employing other nitroxides or nitroxide / alkoxyamine complexes - the process of the application WO 96/30421 which uses atom transfer radical polymerization (ATRP), - the radical polymerization process controlled by Iniferter type control according to the teachings of Otu et al., Makromol. Chem. Rapid. Commun., 3, 127 (1982), - to the controlled radical polymerization process by degenerative transfer of iodine according to the teaching of Tatemoto et al., Jap. 50, 127, 991 (1975), Daikin Kogyo Co. Itd Japan and Matyjaszewski et al., Macromolecules, 28, 2093 (1995), - the radical polymerization process controlled by tetraphenylethane derivatives, disclosed by D. Braun et al. In Macromol. Symp. 111, 63 (1996), or else to the process of radical polymerization controlled by organocobalt complexes described by Wayland et al. In J.Am.Chem.Soc. 116,7973 (1994) - the controlled radical polymerization process with diphenylethylene (WO 00/39169 or WO 00/37507).

  The polymerizations can be carried out in emulsion in water (so-called "latex" process). These processes can use emulsifying agents, most often surfactants. Without wishing to be bound to any theory, it is believed that the emulsion preparation processes lead to the formation of A block nodules, which can influence the physicochemical properties of the copolymer.

  The polymerizations may be carried out in the presence of free radical initiators, known to those skilled in the art. For example, sodium persulfate may be used. Initiator quantities of from 5 to 50% by number relative to the amount of transfer agent can typically be used.

  It is mentioned that it would not be outside the scope of the invention by implementing and adapting preparation processes leading to triblock or star copolymers, subsequently modified (during a step I ') or during step II) so as to obtain diblock copolymers. In particular it is conceivable to use transfer agents comprising several transfer groups (for example trithiocarbonates ZS-CS-SZ) leading to telechelic copolymers of type R - [(block B ') - (block A)] w as triblocks or stars of type (core) - [(block A) - (block B ')] x (for example (block A) - 35 (block B') - R- (block B ') - (block A ) as triblock (block A) - (block B ') - (core) - (block B') - (block A)), then break (cut, "cleave") the telechelic copolymers, to obtain diblock copolymers (block A) - (block B '). The section can intervene during the hydrolysis, in which case diblock copolymers (block A) - (block B) are obtained directly. In such cases, a person skilled in the art will adapt the operating conditions to target average molecular masses equivalent to those indicated, for example by multiplying the quantities of monomers introduced by the number of transfer groups included in the agent. transfer.

  It is specified that during step I) a triblock copolymer 45 is typically not prepared by a succession of 3 polymerization phases in which at least one of the blocks could not be separated from the others by a break during hydrolysis. Thus, the copolymer prepared in step I), is not typically obtained by a polymerization process comprising a step of polymerization of styrene or a styrene-based monomer mixture, and then a polymerization step of ethyl acrylate or a mixture of 50 monomers based on ethyl acrylate, then a step of polymerization of styrene or a mixture of styrene-based monomers, the polymerizations being carried out with the aid of a monofunctional transfer agent bearing a group of formula ûS-CS-. Step II) In step II) the respective amounts of the different units in the B block are controlled by the rate of hydrolysis. The composition of the block A may remain unchanged during the hydrolysis, if the block A does not comprise hydrolysable units. However, it is not excluded that the block A is slightly modified during the hydrolysis step.

  Preferably, the hydrolysis step II) is carried out by adding a strong base such as sodium hydroxide or potassium hydroxide. Typically, a proportion by number of base is added relative to the amount of hydrolysable monomer used in step 1b), corresponding approximately to the desired hydrolysis rate, with possibly an excess of a few%. For example, a quantity of sodium hydroxide 75% by number of the amount of hydrolyzable ethyl acrylate implemented in step lb) is introduced. It is preferably carried out by homogeneous hydrolysis by gradually adding the sodium hydroxide to the copolymer.

  The hydrolysis step may notably result in the deactivation and / or the sectioning of certain transfer groups or other groups attached to the macromolecular chains. Step II) can thus generate by-products that it is desirable to eliminate, or generate groups on the macromolecular chains that are desirable to chemically modify. Such operations can be implemented during a step III).

Step III)

  Step III) is a step of deactivating transfer groups carried by macromolecular chains, and / or purification of the diblock copolymer (Block A) - (Block B) and / or destruction of hydrolysis byproducts. and / or deactivation.

  In optional step III), the resulting block copolymers or hydrolysis byproducts may undergo a purification or destruction reaction of certain species, for example by hydrolysis, oxidation, reduction, pyrolysis processes. , ozonolysis or substitution. An oxidation step with hydrogen peroxide is particularly suitable for treating sulfur species. It is mentioned that some of these reactions or operations may take place in whole or in part during step II). In this case, for these reactions or operations, the two steps simultaneously.

  As indicated above, the average molecular weights of the diblock copolymer (block A) - (block B ') before hydrolysis or of each of the blocks are typically a function of the relative amounts of the monomers and transfer agent used in step a). Of course, the average molecular weights of the diblock copolymer (block A) - (block B) after hydrolysis or of each of the blocks are a function of these same relative amounts and also of the degree of hydrolysis, for example depending on the amount of reagent introduced, usually a base, for this hydrolysis.

  For the sake of simplicity, it is common to express the average molecular masses of the blocks in "theoretical" or "target" average molecular weights, considering a complete and perfectly controlled polymerization. In this case a macromolecular chain is formed by transfer agent; to obtain the molecular mass it suffices to multiply the average molar mass of the units of a block by the number of units per block (quantity in number of monomers per quantity in number of transfer agent). In these calculations, the differences induced by small amounts of co-monomers such as methacrylic acid can be ignored. The theoretical or target average molecular masses of the B block are expressed by considering a total hydrolysis (the masses are expressed with the fiction of a hydrolysis rate of 1).

  For the process of which steps 1a) and 1b) have been detailed above, the theoretical total mass of block A can be expressed as: MAnA.

  For the process of which steps la) and lb) have been detailed above, the theoretical or target average molecular weight of block A can be expressed as: MAnA / nT.

  For the process whose steps la) and lb) have been detailed above, the theoretical total mass of the block B 'can be expressed as: MBnB. For the process of which steps la) and lb) have been detailed above, the theoretical or target average molecular weight of block B 'can be expressed as: MBnB / nT

  For the process of which steps la) and lb) have been detailed above, the theoretical total mass of block B can be expressed as: TMAAnB + (1-T) MBnB

  For the process of which steps la) and lb) have been detailed above, the theoretical or target average molecular weight of block B can be expressed as: MAA nB / nT. (because T = 1 according to the definition of the theoretical or target average molecular weight)

  For the process of which steps la) and lb) have been detailed above, the theoretical total mass of the copolymer can be expressed as: MAnA + T MAA nB + (1-T) MB nB

  For the process of which steps la) and lb) have been detailed above, the theoretical average molecular weight of the copolymer can be expressed as: nA / nT MA + MAA nB / nT

  In the above expressions: MA is the molar mass of styrene or monomer mixture comprising styrene used in step la); MAA is the molar mass of acrylic acid; MB is the molar mass of the C 1 -C 4 alkyl acrylate or of the monomer mixture comprising the C 1 -C 4 alkyl acrylate used in step 1b).

  By way of reference, the following correspondences are given: 40 - nA / nT = 5 corresponds to a theoretical average molecular weight of block A of about 500 g / mol - nA / nT = 5000 corresponds to a theoretical average molecular weight of block A of about 500000 g / mol, nB / nT = 5 corresponds to a theoretical average molecular weight of the block B 'of approximately 45 500 g / mol -nB / nT = 5000 corresponds to a theoretical average molecular mass of the block B' about 500000 g / mol. - nA / nT MA + MAA nB / nT = 13000 g / mol (respectively 2000, respectively 8000, respectively 20000 or 50000) corresponds to a theoretical average molecular weight of the diblock (block A) - (block B) 50 of about 13000 g / mol (respectively 2000, respectively 8000, respectively 20000 or 50000), considering a total hydrolysis, for the case where the alkyl acrylate is ethyl acrylate.

  The weight ratios between the blocks are defined as the ratios between theoretical or target total masses (the descriptor does not use the fiction of a hydrolysis rate of 1). Thus: -MAnA <T MAA nB + (1-T) MB nB, indicates that the weight ratio (block B) / (block A)? 1. This is a characteristic of the copolymer used according to the invention, - MAnA / [MAnA + T MAA nB + (1-T) MB nB] indicates the quantity by weight of block A in the diblock copolymer (block A) - (block B), that is to say the proportion of block A.

  [MAnA + T MAA nB + (1-T) MB nB] indicates the amount by weight of block B in the diblock copolymer (block A) - (block B), that is, the proportion of block B.

  Preferably, the diblock (block A) - (block B) linear copolymers of the type (1) in which the proportion by weight of the block B with respect to the copolymer [T MAA nB + (1-T) MB nB] / [ MAnA + T MAA nB + (1-T) MB nB] is between 50 and 85%. And generally have a theoretical average molecular weight (nA / nT MA + MAA nB / nT) of less than 13000 g / mol.

  Among these copolymers: - those particular of the type (la) where the proportion by weight of the block B with respect to the copolymer [T MAA nB + (1-T) MB nB] / [MAnA + T MAA nB + (1-T ) MB nB] is greater than or equal to 75% (BOL 20) and preferably between 75 and 85% generally have a theoretical average molecular weight (nA / nT MA + MAA nB / nT) of less than 8000 g / mol and preferably between 2000 and 8000 g / mol. those particular of the type (Ib) where the proportion by weight of the block B with respect to the copolymer [T MAA nB + (1-T) MB nB] / [MAnA + T MAA nB + (1-T) MB nB] is less than 75% by weight (BOL 21), preferably between 50% and 75%, generally have a theoretical average molecular weight (nA / nT MA + MAA nB / nT) greater than or equal to 8000 g / mol and preferably between 8000 g / mol and 13000 g / mol.

  Preferably, the diblock linear copolymers (block A) - (block B) of the type (2) in which the proportion by weight of the block B with respect to the copolymer [T MAA nB + (1-T) MB nB] / [MAnA + T MAA nB + (1-T) MB nB] is greater than or equal to 85% (BOL 44 and 55 and 64) and generally have a theoretical average molecular weight (nA / nT MA + MAA nB / nT) greater than or equal to 13000 g / mol. Among these copolymers of the type (2), those particular of the type (2a), in which the proportion by weight of the block B with respect to the copolymer is greater than or equal to 87%, in particular greater than or equal to 87% and less than 94%. %, generally have a theoretical average molecular weight of between 13,000 and 20,000 g / mol. those particular of the type (2b) in which the proportion by weight of the block B with respect to the copolymer is greater than or equal to 94%. in particular ranging from 94% to 97%, generally have a theoretical average molecular mass greater than or equal to 20000 g / mol and preferably greater than or equal to 25000 g / mol, more preferably between 45 20000 and 50000 g / mol and more more preferably between 25,000 and 50,000 g / mol and more particularly between 28,000 and 40,000 g / mol.

  According to one particular embodiment of the invention, a mixture of at least one diblock copolymer of the type (1) and at least one diblock copolymer of the type (2) and more particularly a mixture of at least one diblock copolymer will be used in the emulsions. at least one diblock copolymer of the type (Ia) and at least one diblock copolymer of the type (2b) as defined above.

  The diblock copolymer or copolymers according to the invention are preferably present in concentrations of active material ranging from 0.01 to 5% of the total weight of the composition. More preferably, this amount varies from about 0.05 to 2% by weight in the composition.

  The polar oils used according to the invention preferably have an interfacial oil / water tension measured at 25 ° C. using a Krüss model K12 tensiometer equipped with a Nouy type ring. 35 mN.ml.

  The polar oils in accordance with the invention may be chosen from oils of plant origin, of animal origin, of mineral origin or synthetic oils. They can be used as a mixture.

  As examples of polar oils, mention may be made of those indicated in the following table and ranked in descending order of interfacial oil / water tension: Oil / water interfacial tension at 25 C oil (mN.ml) 43.6 hydrogenated polydecene Hexadecane 42.8 Phenyltrimethylsiloxy trisiloxane 42.8 Isoparaffin 41.0 Dodecane 38.5 Isododecane 31.0 Palmitate 2-ethyl hexyl 31.1 Jojoba oil 29.9 Octyl-2-dodecanol 28.9 Isononyl isononanoate 27, 0 Isopropyl myristate 27.2 Apricot kernel oil 27.0 Caprylic / capric acid triglycerides 25.2 Isopropyl palmitate 25.2 C12-C15 alcohol benzoate 23.2 Dicaprylyl maleate 24, (2-ethylhexyl) adipate 20.7 Isostearyl neopentanoate 14.2 Glyceryl 2-ethylhexyl ether palmitate 13.7 Dialkyl tartrate 12.9 Polar oil or polar oils are preferably present in ranging from 3 to 50% by weight relative to the total weight of the composition. More preferably, this amount varies from 5 to 40% by weight relative to the total weight of the composition.

  Among the lipophilic UV filters that can be used according to the invention, mention may be made of those chosen from anthranilates; cinnamic derivatives; dibenzoylmethane derivatives; salicylic derivatives, camphor derivatives; triazine derivatives such as those described in patent applications US 4367390, EP863145, EP517104, EP570838, EP796851, EP775698, EP878469, EP933376, EP507691, EP507692, EP790243, EP944624; benzophenone derivatives; 13,13-diphenylacrylate derivatives; benzotriazole derivatives; benzalmalonate derivatives including those cited in US5624663; benzimidazole derivatives; imidazolines; p-aminobenzoic acid derivatives (PABA); benzoxazole derivatives as described in patent applications EP0832642, EP1027883, EP1300137 and DE10162844; filter polymers and silicone filters such as those described in particular in the application WO-93/04665; dimers derived from α-alkylstyrene such as those described in patent application DE19855649, 4,4-diarylbutadienes such as those described in patent applications DE19755649, EP916335, EP1133980, EP1133981 and EP-A-1008586 and mixtures thereof .

  Examples of lipophilic organic filters that may be mentioned are those referred to above under their INCI name:

  Derivatives of para-aminobenzoic acid: Ethyl PABA, Ethyl Dihydroxypropyl PABA, Ethylhexyl Dimethyl PABA sold in particular under the name ESCALOL 507 by ISP,

  Salicylic derivatives: Homosalate sold under the name Eusolex HMS by Rona / EM Industries, Ethylhexyl Salicylate sold under the name NEO HELIOPAN OS by Haarmann and REIMER, TEA Salicylate, sold under the name NEO HELIOPAN TS by Haarmann and REIMER,

  Derivatives of dibenzoylmethane: Butyl Methoxydibenzoylmethane sold in particular under the trade name PARSOL 30 1789 by HOFFMANN LAROCHE, Isopropyl Dibenzoylmethane,

  Cinnamic derivatives: Ethylhexyl methoxycinnamate sold in particular under the trade name Parsol 35 MCX by Hoffmann Laroche, Isopropyl Methoxy Cinnamate, Isoamyl Methoxy Cinnamate sold under the trade name NEO HELIOPAN E 1000 by HAARMANN and REIMER, Cinoxate, Diisopropyl Methylcinnamate,

  Derivatives of R, 13-diphenylacrylate: Octocrylene sold in particular under the trade name UVINUL N539 by BASF, Etocrylene, sold in particular under the trade name UVINUL N35 by BASF, 45 Benzophenone derivatives: Benzophenone-1 sold under the trade name Uvinul 400 by BASF, Benzophenone-2 sold under the trade name UVINUL D50 by BASF Benzophenone-3 or Oxybenzone, sold under the trade name Uvinul M40 by 50 BASF, Benzophenone-6 sold under the trade name Helisorb 11 by Norquay Benzophenone-8 sold under the name commercial Spectra-Sorb UV-24 by American Cyanamid Benzophenone-9 sold under the trade name UVINUL DS-49 by BASF, n-hexyl 2- (4-diethylamino-2-hydroxybenzoyl) benzoate

  Derivatives of phenyl benzimidazole: Phenylbenzimidazole Sulfonic Acid sold in particular under the trade name 5 Eusolex 232 by Merck, Disodium Phenyl Dibenzimidazole Tetrasulfonate sold under the trade name NEO HELIOPAN AP by Haarmann and REIMER,

  Derivatives of benzylidene camphor: 3-Benzylidene camphor manufactured under the name MEXORYL SD by CHIMEX, 4-Methylbenzylidene camphor sold under the name EUSOLEX 6300 by MERCK,

  Triazine derivatives: Bis-Ethylhexyloxyphenol Methoxyphenyl Triazine sold under the trade name TINOSORB S by CIBA GEIGY, Ethylhexyl triazone sold in particular under the trade name UVINUL T150 by BASF, Diethylhexyl Butamido Triazone sold under the trade name UVASORB HEB by SIGMA 3V 20 2, 4,6-tris (dineopentyl 4'-amino benzalmalonate) -s-triazine 2,4,6-tris- (4'-amino benzalmalonate diisobutyl) -s-triazine.

  Derivatives of benzotriazole: Drometrizole Trisiloxane sold under the name Silatrizole by Rhodia Chimie, Anthranilic Derivatives: Menthyl Anthranilate sold under the trade name NEO HELIOPAN MA by Haarmann and REIMER,

  Imidazoline Derivatives: Ethylhexyl Dimethoxybenzylidene Dioxoimidazoline Propionate,

  Derivatives of benzalmalonate: Di-neopentyl 4'-methoxybenzalmalonate Polyorganosiloxane with benzalmalonate functions such as polysilicone-15 sold under the trade name PARSOL SLX by HOFFMANN LAROCHE

4,4-diarylbutadiene: 1,1-dicarboxy- (2'2'-dimethylpropyl) -4,4-diphenylbutadiene benzoxazole derivatives: 2,4-bis- [5-1 (dimethylpropyl) benzoxazol-2-yl (4-phenyl) imino] -6 (2-ethylhexyl) imino-1,3,5-triazine sold under the name Uvasorb K2A by Sigma 3V; and their mixtures. The lipophilic organic filters which are more particularly preferred are chosen from the following compounds: Homosalate Ethylhexyl Salicylate, 50 Ethylhexyl Methoxycinnamate Octocrylene, Butyl Methoxydibenzoylmethane Phenylbenzimidazole Sulfonic Acid Disodium Phenyl Dibenzimidazole Tetrasulfonate 55 Benzophenone-3, 40 2- (4-diethylamino) -2 n-hexyl-4-methylbenzylidene camphor, 2,4,6-tris (dineopentyl 4'-amino benzalmalonate) -s-triazine 2,4,6-tris- (4'-amino benzalmalonate) diisobutyl) -s-triazine Bis-Ethylhexyloxyphenol Methoxyphenyl Triazine Ethylhexyl triazone, Diethylhexyl Butamido Triazone, Drometrizole Trisiloxane Polysilicone Di-neopentyl 4'-methoxybenzalmalonate 1,1-dicarboxy- (2'2'-dimethyl-propyl) -4.4- diphenylbutadiene 2,4-bis- [5-1 (dimethylpropyl) benzoxazol-2-yl- (4-phenyl) imino] -6 (2-ethylhexyl) imino-1,3,5-triazine and mixtures thereof.

  And even more preferentially among Homosalate Ethylhexyl Salicylate, Ethylhexyl Methoxycinnamate Octocrylene, Butyl Methoxydibenzoylmethane Ethylhexyl Triazone, Bis-Ethylhexyloxyphenol Methoxyphenyl Triazine Diethylhexyl Butamido Triazone, Drometrizole Trisiloxane The lipophilic filters according to the invention are preferably present in the compositions according to the invention at a content ranging from 0.1% to 30% by weight and preferably from 0.5 to 15%, by weight, relative to the total weight of the composition. The inorganic insoluble UV filters used in accordance with the present invention are metal oxide. More preferably, the inorganic UV filters of the invention are metal oxide particles having an average element particle size of less than or equal to 500 nm, more preferably between 5 nm and 500 nm, and even more preferentially between 10 nm. and 100 nm, and preferably between 15 and 50 nm.

  They may be chosen in particular from oxides of titanium, zinc, iron, zirconium, cerium or their mixtures.

  Such metal oxide pigments, coated or uncoated are in particular described in patent application EP-A-0 518 773. As commercial pigments can be mentioned the products sold Kemira, Tayca, Merck and Degussa.

  The metal oxide pigments may be coated or uncoated.

  The coated pigments are pigments which have undergone one or more surface treatments of a chemical, electronic, mechanochemical and / or mechanical nature with compounds such as amino acids, beeswax, fatty acids, fatty alcohols, anionic surfactants, lecithins, sodium, potassium, zinc, iron or aluminum salts of fatty acids, metal alkoxides (of titanium or aluminum), polyethylene, silicones, proteins (collagen, elastin) , alkanolamines, silicon oxides, metal oxides or sodium hexametaphosphate. The coated pigments are more particularly titanium oxides coated with: - silica such as the product "Sunveil" from the company IKEDA, - silica and iron oxide such as the product "SUNVEIL F" from the company IKEDA, - silica and alumina, such as the products "MICROTITANIUM DIOXIDE MT 500 SA" and "MICROTITANIUM DIOXIDE MT 100 SA" from the company TAYCA, "TIOVEIL" from the company TIOXIDE, - alumina such as the products "TIPAQUE TTO- 55 (B) "and" TIPAQUE TTO-55 (A) "from ISHIHARA, and" UVT 14/4 "from KEMIRA, - aluminum alumina and stearate such as" MICROTITANIUM DIOXIDE MT " 100 T, MT 100 TX, MT 100 Z, MT-01 "from the company TAYCA, the products" Solaveil CT-10 W "and" Solaveil CT 100 "from the company UNIQEMA and the product" Eusolex T-AVO "from the MERCK company, - silica, alumina and alginic acid such as the product "MT-100 AQ" from TAYCA, - alumina and aluminum laurate such as the product "MICROTITANIUM DI OXIDE MT 100 S "from TAYCA, - iron oxide and iron stearate such as the product" MICROTITANIUM DIOXIDE MT 100 F "from TAYCA, - zinc oxide and zinc stearate such as the product "BR 351" from TAYCA, - silica and alumina and treated with a silicone such as the products "MICROTITANIUM DIOXIDE MT 600 SAS", "MICROTITANIUM DIOXIDE MT 500 SAS" or 20 "MICROTITANIUM DIOXIDE MT 100 SAS "from the company TAYCA, - silica, alumina, aluminum stearate and treated with a silicone such as the product" STT-30-DS "from the company TITAN KOGYO, - silica and treated with a silicone such that the product "UV-TITAN X 195" from the company KEMIRA, 25-alumina and treated with a silicone such as the products "TIPAQUE TTO-55 (S)" from the company ISHIHARA, or "UV TITAN M 262" from the company KEMIRA, - triethanolamine such as the product "STT-65-S" from TITAN KOGYO, - stearic acid such as the product "TIPAQUE TTO-55 (C)" e the company ISHIHARA, sodium hexametaphosphate such as the product "MICROTITANIUM DIOXIDE MT 30 150 W" from the company TAYCA. the TiO 2 treated with octyl trimethyl silane sold under the trade name "T 805" by the company Degussa Silices, the TiO 2 treated with a polydimethylsiloxane sold under the trade name "70250 Cardre UF Ti02S13" by CARDRE, 35 - the anatase / rutile TiO2 treated with a polydimethylhydrogensiloxane sold under the trade name "MICRO TITANIUM DIOXIDE USP GRADE HYDROPHOBIC" by the company COLOR TECHNIQUES.

  Uncoated titanium oxide pigments are for example sold by the company TAYCA 40 under the trade names "MICROTITANIUM DIOXIDE MT 500 B" or "MICROTITANIUM DIOXIDE MT600 B", by the company DEGUSSA under the name "P 25", by the company WACKHER under the name "transparent titanium oxide PW", by the company MIYOSHI KASEI under the name "UFTR", by the company TOMEN under the name "ITS" and by the company TIOXIDE under the name "TIOVEIL AQ".

  The uncoated zinc oxide pigments are, for example: those marketed under the name "Z-cote" by the company Sunsmart; those marketed under the name "Nanox" by the company Elementis; 50 - those marketed under the name "Nanogard WCD 2025" by Nanophase Technologies;

  The coated zinc oxide pigments are, for example: those sold under the name "Zinc Oxide CS-5" by the company Toshibi 55 (ZnO coated with polymethylhydrogenosiloxane); 45 - those marketed under the name "Nanogard Zinc Oxide FN" by Nanophase Technologies (as a 40% dispersion in Finsolv TN, C12-C15 alcohol benzoate); those marketed under the name "DAITOPERSION ZN-30" and "DAITOPERSION Zn-50" by Daito (dispersions in cyclopolymethylsiloxane / polydimethylsiloxane oxyethylenated, containing 30% or 50% of zinc nano-oxides coated with silica and polymethylhydrogeniloxane; ); those marketed under the name "NFD Ultrafine ZnO" by the company Daikin (ZnO coated with perfluoroalkyl phosphate and a copolymer based on perfluoroalkylethyl dispersed in cyclopentasiloxane); those marketed under the name "SPD-Z1" by Shin-Etsu (ZnO coated with silicone-grafted acrylic polymer, dispersed in cyclodimethylsiloxane); those marketed under the name "Escalol Z100" by the company ISP (ZnO treated alumina and dispersed in the mixture methoxycinnamate ethylhexyl / copolymer PVP-hexadecene / methicone); those marketed under the name "Fuji ZnO-SMS-10" by the company Fuji Pigment (ZnO coated with silica and polymethylsilsesquioxane); those marketed under the name "Nanox Gel TN" by Elementis (ZnO dispersed at 55% in C12-C15 alcohols benzoate with hydroxystearic acid polycondensate).

  The uncoated cerium oxide pigments may be, for example, those sold under the name "COLLOIDAL CERIUM OXIDE" by the company RHONE POULENC.

  Uncoated iron oxide pigments are for example sold by ARNAUD under the names "NANOGARD WCD 2002 (FE 45B)", "NANOGARD IRON FE 45 BL AQ", "NANOGARD FE 45R AQ," NANOGARD WCD 2006 ( FE 45R) ", or by the company MITSUBISHI under the name" TY-220 ".

  The coated iron oxide pigments are for example sold by ARNAUD under the names "NANOGARD WCD 2008" (FE 45B FN) "," NANOGARD WCD 2009 (FE 45B 556) "," NANOGARD FE 45 BL 345 "," NANOGARD FE 45 BL ", or by the company BASF under the name" OXIDE OF CLEAR IRON ".

  Mention may also be made of mixtures of metal oxides, in particular titanium dioxide and cerium dioxide, including the titanium dioxide / silica-coated cerium-aluminum alloy mixture sold by the company IKEDA under the name "SUNVEIL A". ", as well as the mixture of titanium dioxide and zinc dioxide coated with alumina, silica and silicone such as the product" M 261 "sold by the company KEMIRA or coated with alumina, silica and glycerin such as that the product "M 211" sold by KEMIRA.

  According to the invention, titanium oxide pigments, coated or uncoated, are particularly preferred. The insoluble inorganic filters according to the invention generally represent from 0.5 to 40%, preferably from 1 to 30%, of the total weight of the emulsion.

  Depending on their lipophilic nature, or on the contrary hydrophilic, more or less pronounced, the 50 mineral filters may be present either in the fatty phase of the emulsion or in the aqueous phase, or even in both phases at a time.

  The insoluble organic UV filters comprising at least one UV-absorbing group may be chosen in particular from oxalanilide, triazine, benzotriazole, vinyl amide, cinnamide, benzazole, benzofuran, arylvinylidene-ketone, and acrylonitrile amide insoluble organic UV filters. acrylonitrile sulfonamide, acrylonitrile carbamate or phenylene-bis-benzoxazinone.

  Among the insoluble UV filters of the oxalanilide type, mention may be made of those corresponding to the formula: (I) in which T1, T1 ', T2 and T2' each independently represent a C1-C8 alkyl radical or a C1-alkoxy radical. C8. These compounds are described in WO95 / 22959. By way of examples, mention may be made of the commercial products TINUVIN 315 and TINUVIN 312 sold by the company CIBA-GEIGY respectively corresponding to the formulas: C (CH 3) 3. The insoluble triazine type filters correspond to the following general formula: Wherein each of R 1, R 2 and R 3 is independently unsubstituted phenyl, phenoxy or pyrrolo or each independently having one, two or three substituents selected from -OH, C 1 -C 18 alkyl, C 1 -C 18 alkoxy, carboxy ( C1-18 alkyl), C5-C8 cycloalkyl, methylbenzylidene camphor, - (CH = CR ') n (CO) OR4 where R' represents a hydrogen atom, a cyano group or a COOR4 group, with R4 = C1-C18 alkyl or cinnamyl, and n is 0 or 1. These compounds are described in WO 97/03643, GB 2286774, EP 743309, WO 98/22447, GB 2319523 and EP-AO 790 243.

  The following compounds are more particularly mentioned: - 2,4,6-tris (4'-aminobenzalmalonate diethyl) -s-triazine, 2,4,6-tris (4'-amino benzalmalonate diisopropyl) -s-triazine, 2,4,6-tris (dimethyl 4'-aminobenzalmalonate) -s-triazine, ethyl 2,4,6-tris (4-cyano-4-aminocinnamate) s-triazine.

  Among the triazine type UV filters that can be used for the present invention, mention may also be made of the insoluble s-triazine derivatives bearing benzotriazole and / or benzothiazole groups such as those described in the application WO98 / 25922. Among these compounds, mention may be made more particularly of 2,4,6-tris [(3'-benzotriazol-2-yl-5'-hydroxy-5'-methyl) -phenylamino] -s-triazine and the 2,4,6-tris [(3'-benzotriazol-2-yl-2'-hydroxy-5'-ter-octyl) -phenyl-amino] -s-triazine.

  Among the insoluble organic UV-screening agents of the benzotriazole type, mention may be made of those of formula (III) below, described for example in international application WO95 / 22959: in which R5 denotes a hydrogen atom or a C1-alkyl radical. -C 18, R 6 and R 7, which are identical or different, each independently denote a C 1 -C 18 alkyl radical optionally substituted with a phenyl group.

  By way of examples of compounds of formula (III), mention may be made of the commercial products TINUVIN 328, 320, 234 and 350 of the company CIBA-GEIGY corresponding respectively to the following formulas: C (CH 3) 3 HO C (CH 3) 2CH 2 CH 3 C (CH 3) 2 CH 2 CH 3 C (CH 3) 3 Among the benzotriazole-type insoluble organic UV-screening agents, mention may also be made of the compounds described in patents US5687521, US5687521, US5373037, US5362881, and among them in particular the [2, 4 4-Dihydroxy-3- (2H-benzotriazol-2-yl) -5- (1,1,3,3-tetramethylbutyl) -2'-n-octoxy-5'-benzoyl] diphenylmethane of the formula: OH-OH-TertC8H17 H2 sold under the name MIXXIM PB30 by FAIRMOUNT CHEMICAL.

  Other insoluble organic benzotriazole type UV screening agents are methylenebis (hydroxyphenylbenzotriazole) derivatives having the following structure: ## STR5 ## in which R 8 and R 9, which may be identical or different, each represent a C 1 -C 18 alkyl radical which may be substituted by one or more radicals selected from C 1 -C 4 alkyl, C 5 -C 12 cycloalkyl or aryl. These compounds are known and are described in the applications US 5237071, US 5166355, GB-A-2 303549, DE 19726184 and EP-A-893119.

  In the formula (IV) defined above, the C 1 -C 18 alkyl groups may be linear or branched and are, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, tert-butyl and the like. octyl, n-amyl, n-hexyl, n-heptyl, n-octyl, isooctyl, n-nyl, n-decyl, n-undecyl, n-dodecyl, tetradecyl, hexydecyl, or octadecyl; C 5 -C 12 cycloalkyl groups are, for example, cyclopentyl, cyclohexyl, cyclooctyl; aryl groups are for example phenyl, benzyl.

  Among the compounds of formula (IV), those of the following structure are more particularly preferred: compound (a) compound (b) N OH N N N CH 2 N / N compound (c) N OH OH N 1 N, N CH 2 L CH3 CH3 The compound (a) of the nomenclature 2,2'-methylene-bis- [6- (2H-benzotriazol-2-yl) -4- (1,1,3,3-tetramethylbutyl) phenol] is sold in solid form the name MIXXIM BB / 100 by the company FAIRMOUNT CHEMICAL and in micronized form under the name TINOSORB M by the company by CIBA SPECIALTY CHEMICALS.

The compound (c) of 2,2'-methylene-bis- [6- (2H-benzotriazol-2-yl) -4- (methyl) phenol] is sold in solid form under the name MIXXIM BB / 200 by the FAIRMOUNT CHEMICAL company.

  Among the insoluble organic vinylide amide filters, there may be mentioned, for example, the compounds of formula (V) which are described in application WO95 / 22959:

  T3- (Y) rC (= O) -C (T4) = C (T5) -N (T6) (T7) (V) in which T3 is a C1-C18 alkyl radical, preferably C1-C5 alkyl, or a phenyl group optionally substituted with one, two or three radicals selected from OH, (C1-C18) alkyl, (C1-C8) alkoxy or (O) -OT8 where T8 is (C1-C18) alkyl; T4, T5, T6 and T7 are each independently C1-C18 alkyl, preferably C1-C5, or hydrogen; Y is -NH- or oxygen and r is 0 or 1.

  Among these compounds, mention will be made more particularly: 4-octylamino-3-penten-2-one; ethyl 3-octylamino-2-butenoate; 3-octylamino-1-phenyl-2-buten-1-one 3-dodecylamino-1-phenyl-2-buten-1-one.

  Among the cinnamide-type organic screening agents, mention may be made of compounds such as those described in application WO 95/22959 and corresponding to the following formula: ## STR1 ## in which R10 represents a hydrogen atom or a hydrogen atom. C1-C4 alkyl group preferably methyl or ethyl, R11 represents a hydrogen atom or a C1-C4 alkyl group, preferably methyl or ethyl, R12 represents a group - (CONH) S phenyl where s is 0 or 1 and the phenyl group may be substituted with one, two or three groups selected from OH, C 1 -C 18 alkyl, C 1 -C 8 alkoxy or C (= O) -OR 13 where R 13 is C 1 -C 18 alkyl, and more preferably R12 is phenyl, 4-methoxyphenyl or phenylaminocarbonyl.

  It is also possible to mention bis (cinnamides), di-substituted dimers, described for example in patent US Pat. No. 5,888,481, of the following structure: in which Art and Ar2, which may be identical or different, each represent a phenyl radical, an aromatic heterocycle , a fused phenyl ring group or a fused aromatic heterocycle group, and may bear one or more substituents, identical or different, B and D, different from a hydrogen atom, each independently represent an organic radical, A and Each independently represents an organic radical, and E represents a divalent organic radical, with the exception of compounds for which Art and Ar 2 both represent a phenyl group carrying an OR substituent where R represents a hydrogen atom or a radical; organic, A and C both represent a cyano group, B and D both represent a C 1 -C 35 alkyl or alkenyl group, and E represents a 45 rad Bis organic divalent organic, and in particular the compound of structure: (VII) Among the insoluble organic benzazole type filters, mention may be made of those corresponding to one of the following formulas: (VIII) (A) p (R14) m ( X) (R14) m wherein each of Y is independently oxygen or sulfur or NR15, each of Z is independently N or CH, each of R14 is independently OH group, a halogen atom, a linear or branched C 1 -C 8 alkyl group, optionally containing a silicon atom, or a linear or branched C 1 -C 8 alkoxy group, each of the numbers m is independently 0, 1 or 2, n represents an integer between 1 and 4 inclusive, p is 0 or 1, each of the numbers q is independently 0 or 1, each of R15 independently represents a hydrogen atom, a benzyl group or C1-C8 alkyl, linear or branched , optionally containing a silicon atom, A represents a radical of valence n chosen from those of formulas: (b) (c) (d) (e) (f) (g) (h) (o) (k) Ris (I) Y (m) (n) () wherein each of R16 independently represents a halogen atom or a linear or branched C1-4 alkyl or alkoxy group, or hydroxy, R17 represents a hydrogen atom or a linear or branched C 1 -C 4 alkyl group, c = 0-4, d = 0-3, e = 0 or 1 and f = 0-2.

  These compounds are described in particular in DE 676 103 and CH 350763, US 5501850, US 5961960, EP 0669323, US 5518713, US 2463264, J. Am. Chem. Soc., 79, 5706 - 5708, 1957, the article published in J. Am. Chem. Soc., 82, 609-611, 1960, the patent application EP 0921126 and the patent application EP 0712855.

  As examples of preferred compounds of formula (VIII) of the 2-arylbenzazole family, there may be mentioned 2-benzoxazol-2-yl-4-methylphenol, 2- (1H-benzimidazol-2-yl) - 4-methoxyphenol or 2-benzothiazol-2-ylphenol, these compounds can be prepared for example according to the methods described in patent CH 350 763.

  As examples of preferred compounds of formula (VIII) of the family of benzimidazolylbenzazoles, mention will be made of 2,2'-bis-benzimidazole, 5,5 ', 6,6'-tetramethyl-2,2'-bis benzimidazole, 5,5'-dimethyl-2,2'-bis-benzimidazole, 6-methoxy-2,2'-bisbenzimidazole, 2- (1H-benzimidazol-2-yl) -benzothiazole, 2 - (1H-benzimidazol-2-yl) -benzoxazole and N, N'-dimethyl-2,2'-bis-benzimidazole, these compounds can be prepared according to the procedures described in patents US 5961960 and US 2463264.

  By way of examples of preferred compounds of formula (VIII) of the phenylenebenzazole family, mention will be made of 1,4-phenylenebis (2-benzoxazolyl) and 1,4-phenylenebis (2-benzimidazolyl). 1,3-phenylenebis (2-benzoxazolyl), 1,2-phenylenebis (2-benzoxazolyl), 1,2-phenylenebis (benzimidazolyl), 1,4-phenylene -bis- (N-2-ethylhexyl-2-benzimidazolyl) and 1,4-phenylene-bis- (N-trimethylsilylmethyl-2-benzimidazolyl), these compounds can be prepared according to the procedures I / (Ri s) f (Ride WWW ~ / WW / W 20 3035 described in US Patent 2,463,264 and in J. Am.Chem.Soc., 82, 609 (1960) and J. Am.Chem.Soc., 79, 5706-5708. (1957).

  Examples of preferred compounds of formula (VIII) of the benzofuranylbenzoxazole family are 2- (2-benzofuranyl) -benzoxazole, 2- (benzofuranyl) -5-methylbenzoxazole and 2- (3-benzofuranyl) benzoxazole. 2-methyl-2-benzofuranyl) -benzoxazole, these compounds may be prepared according to the procedures described in US Pat. No. 5,518,713.

  Preferred compounds of formula (IX) include, for example, 2,6-diphenyl-1,7-dihydro-benzo [1,2-d; 4,5-d] -diimidazole corresponding to the formula 2,6-distyryl-1,7-dihydro-benzo [1,2-d; 4,5-d1-diimidazole or else 2,6-di (p-tert-butylstyryl) -1,7-dihydrobenzo [1,2-d; 4,5-d '] - diimidazole, which can be prepared according to the processes described in application EP 0 669 323.

  As preferred compound of formula (X), there may be mentioned 5,5'-bis - [(phenyl-2) -benzimidazole] of formula: H H whose preparation is described in J. Chim. Phys., 64, 1602 (1967). especially 2- (1H-benzimidazol-2-yl) benzoxazole, 6-methoxy-2,2'-bis-benzimidazole, 2- (1H-benzimidazol-2-yl) -benzothiazole, 1,4-phenylene -bis- (2-benzoxazolyl), 1,4-phenylene-bis- (2-benzimidazolyl), 1,3-phenylene-bis- (2-benzoxazolyl), 1,2-phenylene-bis- (2-benzoxazolyl) Another family of insoluble filters is that of the arylvinylene ketones chosen from those corresponding to one of the following formulas (XI) and (XII): Among these insoluble organic compounds filtering UV radiation, all benzimidazolyl) and 1,4-phenylene-bis- (N-trimethylsilylmethyl-2-benzimidazolyl) are preferred. Wherein: n = 1 or 2, A, in formula (XI) when n = 1 or in formula (XII), is an aryl radical selected from the following formulas (a) to (d), or in the formula (XI) when n = 2, is a radical chosen from the following formulas (e) to (h): (R4) p (a) (b) (c) (d) (0) (e) (f) (g) (h) wherein: each of R4 is independently an OH group, a halogen atom, a C1-C6 linear or branched alkyl group and optionally containing a silicon atom, an alkoxy group C1-C6, linear or branched and optionally containing a silicon atom, a C1-C5 alkoxycarbonyl group, linear or branched, or a C1-C6 alkylsulfonamide group, linear or branched and optionally containing a silicon atom or a function amino acid, p is an integer from 0 to 4 inclusive, q is 0 or 1, R 1 is hydrogen or OH, R 2 is hydrogen, C 1 -C 4 alkyl; 1-C6, linear or branched and optionally containing a silicon atom, a cyano group, a C 1 -C 6 alkylsulfonyl group, a phenylsulfonyl group, R 3 represents a linear or branched C 1 -C 6 alkyl group and optionally containing an atom of silicon or a phenyl group which can form a bicycle and optionally substituted with one or two radicals R4, or R2 and R3 together form a C2-C10 hydrocarbon radical which is monocyclic, bicyclic or tricylic, optionally interrupted by one or more nitrogen atoms , sulfur and oxygen and may contain another carbonyl, and optionally substituted by a linear or branched C1-C8 alkylsulfonamide group, and optionally containing a silicon atom or an amino acid function; provided that when n = 1, R2 and R3 do not form a camphor ring. By way of examples of compounds of formula (XI) in which n = 1, insoluble, filtering UV radiation, there may be mentioned the following families: Styryl Ketone (Kao JP 04 134 042) such as 1- (3, 4-dimethoxy-phenyl) -4,4-dimethylpent-1-en-3-one: MeO 15 Benzylidene Cineole (E. Mariani et al., 16th IFSCC Congress, New York (1990)) such as 1,3, 3-trimethyl-5- (4-methoxy-benzylidene) -2-oxa-bicyclo [2.2.2] octan-6-one: O-Benzylidene Chromanone (Kao JP 04 134 043) such as 3- (4-methoxy) benzylidene) -2,3,4a, 8a-tetrahydro-chromen-4-one: OO OMe Benzylidene Thiochromanone (Kao JP 04 134 043) such as 3- (4-methoxy-benzylidene) -2,3,4a , 8a-tetrahydro-chromen-4-thione: OS OMe Benzylidene Quinuclidinone (Merck EP 0 576 974) such as 4-methoxybenzylidene-1-aza-bicyclo [2.2.2] octan-3-one: Benzylidene Cycloalkanone (Henkel FR 2,395,023) such as 2- (4-methoxybenzylidene) -cyclopentanone and 2- (4-methoxy-benzylidene) -cyclohexanone: MeO MeO Benzylidene Hydantoin (Ajinomoto JP 01 158 090) such as 5- (3,4-dimethoxy-benzylidene) -imidazolidine-2,4-dione: O MeO NH H (O Benzylidene Indanone (Kao JP 04 134 043) such that 2- (4-methoxy-benzylidene) -indan-1-one: MeO OMe Benzylidene Tetralone (Kao JP 04 134 043) such as 2- (4-methoxy-benzylidene) -3,4-dihydro-2H -naphthalen-1-one: OMe Benzylidene Furanone (L'Oreal EP 0 390 683) such as 4- (4-methoxy-benzylidene) -2,2,5,5-tetramethyl-dihydro-furan-3-one : OMe 15Benzylidene Benzofuranone (Kao JP 04 134 041) such as 2-benzylidene-benzofuran-3-one: Benzylidene Indanedione such as 2- (3,5-di-tert-butyl-4-hydroxy-benzylidene) - indan-1,3-dione: benzylidene benzothiofuranone (Kao JP 04,134,043) such as 2-benzylidene-benzo [b] thiophen-3-one: benzylidene barbiturate such as 5- (4-methoxy-benzylidene) -1,3 dimethylpyrimidine-2,4,6-trione: O Benzylidene Pyrazolone such as 4- (4-methoxy-benzylidene) -5-methyl-2-p phenyl-2,4-dihydro-pyrazol-3-one: O MeO Benzylidene Imidazolone such as 5- (4-methoxy-benzylidene) -2-phenyl-3,5-dihydro-imidazol-4-one: O-OMe MeO 5 Chalcone such as 1- (2-hydroxy-4-methoxy-phenyl) -3-phenyl-propenone: OH O MeO Benzylidene One (tautomeric filtering form of dibenzoylmethanes; L'Oréal FR 2,506,156) such as 3-hydroxy-1- (2-hydroxy-4-methoxy-phenyl) -3-phenyl-propenone: Examples of compounds of formula (XI) in which n = 2 insoluble, filtering the UV radiation, may be mentioned the following families:

  Phenylene bis methylidene-nor-camphor (Merck EP 0 693 471) such as 1,4-phenylene-bis (3-methylidene-bicyclo [2.2.1] heptan-2-one): phenylene bis methylidene camphor (L Oral FR 2,528,420) such as 1,4-phenylenebis (3-methylidene-1,7,7-trimethyl-bicyclo [2.2.1] heptan-2-one) or 1,3-phenylene bis - {3-methylidene-1,7,7-trimethyl-bicyclo [2.2.1] heptan-2-one}: OMe 10 Phenylene bis methylidene camphor sulfonamide (L'Oréal FR 2529887) such as 1,4-phenylene Ethyl or 2-ethylhexylbisbis-3,3'-methylidene camphor-10,10-sulfonamide: Bu Phenylenbis methylidene cineole (E. Mariani et al., 16th IFSCC Congress, New York (1990)), such as 1,4-phenylene-bis- {5-methylidene-3,3-dimethyl-2-oxa-bicyclo [2.2.2] octan-6-one} or phenylene bis-methylidene ketotricyclodecane (Merck EP 0 694 521) such as 1,4-phenylenebis (octahydro-4,7-methano-6-inden-5-one): Phenylenebisalkylene ketone (Kao JP 04 134 041) such as 1,4-phenylene-b is- (4,4-5-dimethyl-pent-1-en-3-one): phenylenebis (methylidene) furanone (L'Oreal FR 2638354) such as 1,4-phenylenebis (4-methylidene-2); 2,5,5-tetramethyl-dihydrofuran-3-one): Phenylene bis-methylidene quinuclidinone (Merck EP 0 714 880) such as 1,4-phenylene-bis (2-methylidene-1-aza-bicyclo) [2.2.2] octan-3-one}: As compounds of formula (XII), there may be mentioned the following families: bis-benzylidene cycloalkanone such as 2,5-dibenzylidene-cyclopentanone: 0 gamma pyrone (Kao JP 04 290 882) such as 2,6-bis- (3,4-dimethoxy-phenyl) -pyran-4-one: Another family of insoluble filters that can be used in the present invention are amide derivatives. , sulfonamides and acrylonitrile carbamate corresponding to the following formula

  Wherein X 2 represents a divalent radical of the formula - (C = O) -R'3- (C = O) -, SO 2 -R "3 -SO 2 - or - (R 2) n (XIII) C = O) -OR "3-0- (C = O) -, Y represents a radical - (C = O) -R4 or -SO2R5, R2 represents a C1-C8 alkyl group, linear or branched, n is 0 , 1 or 2, R'3 represents a single bond or R "3 R" 3 represents a divalent radical C1-C36 alkylene or alkenylene C3-C30, linear or branched, may carry one or more hydroxyl substituents and may contain, in the carbon chain, one or more heteroatoms selected from oxygen, nitrogen and silicon. R4 represents a radical -OR6 or -NHR6, R5 represents a linear or branched C1-C30 alkyl radical, or a phenyl ring which may be substituted by C1-C4 alkyl or alkoxy radicals; R6 represents a C1-C8 alkyl radical; C36 or C3-C30 alkenyl, linear or branched, may carry one or more hydroxyl substituents and may contain, in the carbon chain, one or more heteroatoms selected from oxygen, nitrogen and silicon.

  Although in formula (X111) above, only the isomers in which the cyano substituent is in the cis position relative to the para-aminophenyl substituent are represented, this formula should be understood to include also the corresponding trans isomers for each of the two double bonds and independently, the cyano and para-amino-phenyl substituents may be in a cis or trans configuration with respect to each other.

  Another family of insoluble organic filters that can be used according to the present invention is formed by the phenylene-bis-benzoxazinone derivatives of formula (XIV) wherein R represents a divalent aromatic radical chosen from the following formulas (e) to (h): (0) q (e) (f) (g) (h) in which: each of the symbols R4 independently represents an OH group, a halogen atom or a linear or branched C1-C6 alkyl group and optionally containing a silicon atom, a linear or branched C1-C6 alkoxy group optionally containing a silicon atom, a C1-C5 alkoxycarbonyl group, linear or branched, or a linear or branched C1-C6 alkylsulfonamide group and optionally containing a silicon atom or an amino acid function, p represents an integer between 0 and 4 inclusive, q represents 0 or 1.

  By way of examples of compounds of formula (XIV), which are insoluble and which filter UV radiation, the following derivatives may be mentioned: 2,2'-p-phenylene bis (3,1-benzoxazin-4-one), product CYASORB UV-3638 from CYTEC, 2,2 '- (4,4'-biphenylene) bis (3,1-benzoxazin-4-one), 2,2' - (2,6-naphthylene) bis ( 3,1-benzoxazin-4-one). Another particular family of insoluble organic filters are the polyvalent metal salts (eg Ca 2+, Zn 2+, Mg 2+, Ba 2+, Al 3 + or Zr 4+) of sulfonated or carboxylated organic filters such as polyvalent metal salts of sulfonated benzylidene derivatives. such as those described in application FR-A 2,639,347, the polyvalent metal salts of sulfonated benzimidazole derivatives such as those described in application EP-A-893 119, and the polyvalent metal salts of derivatives thereof. cinnamic acid such as those described in JP-87 166 517.

  Mention may also be made of metal or ammonium or substituted ammonium complexes of organic UV-A and / or UV-B screening agents, such as those described in patent applications WO93 / 10753, WO93 / 11095 and WO95 / 05150. .

  The methylene-bis (hydroxyphenylbenzotriazole) derivatives having the following structure: CH 2 in which R 8 and R 9, which are identical or different, each represent a C 1 -C 18 alkyl radical which may be substituted by one or more, will be chosen more particularly as insoluble organic filter. radicals chosen from C1-C4 alkyl, C5-C12 cycloalkyl or aryl and more particularly the compound of (a) with nomenclature 2,2'-methylene-bis- [6- (2H-benzotriazol-2-yl) -4- (1,1,3,3-tetramethylbutyl) phenol] or Methylene bis-Benzotriazolyl Tetramethylbutylphenol is sold in solid form the name MIXXIM BB / 100 by the company FAIRMOUNT CHEMICAL and in micronized form under the name TINOSORB M by the company by CIBA SPECIALTY CHEMICALS.

  The insoluble organic filters according to the invention are generally in the form of particles of average size ranging from 10 nm to 5 μm. More preferably, their average size varies from 10 nm to 2 μm, and in particular between 20 nm and 1.5 μm, and ideally between 30 nm and 1.0 μm.

  In general, the average particle size will be the average diameter of the number distribution.

  The average size of the particles can be determined by any conventional method such as optical methods (quasi-elastic scattering or laser scattering), centrifugation methods or methods of microscopic visualization and image analysis.

  The insoluble organic filters according to the invention can be brought into the desired particulate form by any ad-hoc means such as in particular dry milling or in a solvent medium, sieving, atomization, micronisation, spraying.

  The insoluble organic filters according to the invention in micronized form can in particular be obtained by a method of grinding an insoluble organic UV filter in the form of coarse particles in the presence of an appropriate surfactant for improving the dispersion. particles thus obtained in cosmetic formulations.

  An example of a method for micronizing insoluble organic filters is described in GB-A-2,303,549 and EP-A-893,119 as an integral part of the description. The grinding apparatus used according to these documents may be a jet mill, ball mill, vibration mill or hammer mill and preferably a high speed grinding mill or an impact mill and more particularly a rotary ball mill, a vibrating mill, tube mill or rod mill.

  According to this particular process, alkylpolyglucosides having the structure CnH 2n + 1 O (C 6 H 100 O) x H in which n is an integer of 8 to 16 and x is the average degree of polymerization are used as surfactants for grinding said filters. of the unit (C6H1005) and ranges from 1.4 to 1.6. They may be chosen from C1-C12 esters of a compound of structure CnH2n + 1O (C6H10O5) XH and more specifically an ester obtained by reaction of a C1-C12 carboxylic acid such as formic acid, acetic acid. propionic, butyric, sulfosuccinic, citric or tartaric with one or more free OH functions on the glucoside unit (C6H1005). Said surfactants are generally used at a concentration of from 1 to 50% by weight and more preferably from 5 to 40% by weight relative to the insoluble filter in its micronized form.

  It is also possible to improve the dispersibility of the organic insoluble filters in the cosmetic support of amphiphilic copolymers comprising at least one hydrophilic block and at least one hydrophobic block, such as those described in the patent application EP1353642.

  The insoluble UV screening agent (s) of the invention are preferably present at a total concentration of between approximately 0.1 and 25% by weight, and preferably between approximately 0.2 and 20% by weight, relative to the total weight of the composition.

  The compositions in accordance with the invention may comprise, in addition to other, additional organic photoprotective agents active in water-soluble UVA and / or UVB.

  The term "hydrophilic photoprotective agent" is understood to mean any UV radiation filtering agent capable of being completely dissolved in the molecular state in the aqueous phase of the emulsion or else to be solubilized in colloidal form (for example in micellar form) in the phase aqueous emulsion.

  Among the hydrophilic organic UV filters that may be used according to the invention, mention may be made of those referred to above under their INCI name: (1) p-aminobenzoic (PABA) derivatives such as - PABA - Glyceryl PABA - PEG-25 PABA sold under the name UVINUL P25 by BASF, 30

  (2) benzophenone derivatives containing at least one sulphonic radical such as - Benzophenone-4 sold under the trade name UVINUL MS40 by BASF, - Benzophenone-5 - Benzophenone-12

  (3) benzylidene camphor derivatives containing at least one sulphonic radical, for example: Benzylidene Camphor Sulfonic Acid manufactured under the name MEXORYL SL by 40 CHIMEX, Camphor Benzalkonium Methosulfate manufactured under the name MEXORYL SO by CHIMEX, -Terephthalylidene Dicamphor Sulfonic Acid manufactured under the name MEXORYL SX by CHIMEX, (4) benzimidazole derivatives containing at least one sulphonic radical such as, for example: Phenylbenzimidazole Sulfonic Acid sold in particular under the trade name EUSOLEX 232 by Merck, 50-bis-benzoazolyl derivatives as described in patents EP669323 and US 2,463,264 and more particularly the compound Disodium Phenyl Dibenzimidazole Tetrasulfonate sold under the trade name NEO HELIOPAN AP by Haarmann and REIMER,

  (5) hydrophilic cinnamate derivatives such as, for example, DEA Methoxycinnamate. (6) their mixtures.

  Among these hydrophilic filters, the most preferred are selected from Terephthalylidene Dicamphor Sulfonic Acid Benzophenone-4 Phenylbenzimidazole Sulfonic Acid Disodium Phenyl Dibenzimidazole Tetrasulfonate and mixtures thereof.

  The additional hydrophilic photoprotective agents are generally present in the compositions according to the invention in proportions ranging from 0.01% to 20% by weight relative to the total weight of the composition, and preferably ranging from 0.1% to 10% by weight. relative to the total weight of the composition.

  The emulsions according to the invention may also contain agents for tanning and / or artificial browning of the skin (self-tanning agents).

  The self-tanning agents are generally chosen from mono or polycarbonyl compounds such as, for example, isatin, alloxane, ninhydrin, glyceraldehyde, mesotartaric aldehyde, glutaraldehyde, erythrulose, pyrazolin-4,5 derivatives. -Diones as described in patent application FR 2 466 492 and WO 97/35842, dihydroxyacetone (DHA), 4,4-dihydroxypyrazolin-5-ones derivatives as described in patent application EP 903 342. DHA will preferably be used.

  DHA may be used in free form and / or encapsulated for example in lipid vesicles such as liposomes, in particular described in application WO 97/25970.

  The mono or polycarbonyl self-tanning agents are generally present in the compositions according to the invention in proportions ranging from 0.1 to 10% by weight relative to the total weight of the composition, and preferably from 0.2 to 8% by weight. relative to the total weight of the composition

  The compositions of the invention may contain all the additives usually used in cosmetics and will find applications in the field of care, make-up and sun products.

  The aqueous compositions in accordance with the present invention may furthermore comprise conventional cosmetic adjuvants, chosen in particular from fatty substances other than the polar oils defined above, organic solvents, ionic or nonionic thickeners, hydrophilic or lipophilic, softeners, humectants , opacifiers, stabilizers, emollients, silicones, antifoams, perfumes, preservatives, anionic, cationic, nonionic, zwitterionic or amphoteric surfactants, actives, fillers, polymers, propellants, alkalinizing or acidifying agents or any other ingredient usually used in the cosmetic and / or dermatological field.

  The fatty substances may consist of an oil or a wax or mixtures thereof. By oil is meant a liquid compound at room temperature. By wax is meant a compound which is solid or substantially solid at ambient temperature and whose melting point is generally greater than 35 C.

  Among the organic solvents, mention may be made of lower alcohols and polyols. These can be selected from glycols and glycol ethers such as ethylene glycol, propylene glycol, butylene glycol, dipropylene glycol or diethylene glycol. As hydrophilic thickeners, mention may be made of carboxyvinyl polymers such as Carbopols (carbomers) and Pemulen (acrylate / C10-C30-alkylacrylate copolymer); polyacrylamides, for example crosslinked copolymers sold under the names Sepigel 305 (CTFA name: polyacrylamide / C13-14 isoparaffin / Laureth 7) or Simulgel 600 (CTFA name: acrylamide / sodium acryloyldimethyltaurate copolymer / isohexadecane / polysorbate 80) by the company Seppic ; polymers and copolymers of 2-acrylamido-2-methylpropanesulphonic acid, optionally cross-linked and / or neutralized, such as poly (2-acrylamido-2-methylpropanesulphonic acid) marketed by Hoechst under the trademark Hostacerin AMPS (CTFA name: ammonium polyacryldimethyltauramide); cellulosic derivatives such as hydroxyethylcellulose; polysaccharides and especially gums such as xanthan gum; and their mixtures.

  Mention may be made, as lipophilic thickeners, of synthetic polymers such as the poly C, o-C 30 alkyl acrylate sold under the name Doresco IPA 13-1 by the company Landec or else modified clays such as hectorite and its derivatives, such as products sold under the Bentone name.

  Of course, those skilled in the art will take care to choose the optional additional compound (s) mentioned above and / or their amounts in such a way that the advantageous properties intrinsically attached to the compositions in accordance with the invention are not, or substantially, not, altered by the addition or additions envisaged.

  The compositions according to the invention may be prepared according to the techniques well known to those skilled in the art of an oil-in-water emulsion. The proportion of the oily phase of the emulsion may range from 1 to 80% by weight, preferably from 2 to 50% by weight and better still from 2 to 40% by weight relative to the total weight of the composition. The fatty substances of the oily phase, in particular the oils, and the emulsifiers and coemulsifiers that may be present, used in the composition in emulsion form are chosen from those conventionally used in the cosmetic or dermatological field. The emulsifier and the co-emulsifier, when present, are generally present in a proportion ranging from 0.1 to 30% by weight, preferably from 0.3 to 20% by weight and better still from 0.5 to 15% by weight relative to the total weight of the composition.

  The emulsions according to the invention generally contain at least one emulsifier chosen from amphoteric, anionic, cationic or nonionic emulsifiers, used alone or as a mixture. The emulsifiers are suitably selected to form an oil-in-water emulsion.

  As emulsifiers, mention may be made of nonionic emulsifiers such as oxyalkylenated (more particularly polyoxyethylenated) fatty acid esters of glycerol; oxyalkylenated fatty acid and sorbitan esters; oxyalkylenated fatty acid esters (oxyethylenated and / or oxypropylenated) such as the PEG-100 Stearate / Glyceryl Stearate mixture marketed for example by the company ICI under the name Arlacel 165; oxyalkylenated fatty alcohol ethers (oxyethylenated and / or oxypropylenated); sugar esters such as sucrose stearate; fatty alcohol and sugar ethers, in particular alkylpolyglucosides (APG) such as decylglucoside and laurylglucoside sold, for example, by Henkel under the respective names Plantaren 2000 and Plantaren 1200, cetostearylglucoside optionally mixed with cetostearyl alcohol; , marketed for example under the name Montanov 68 by the company Seppic, under the name Tegocare CG90 by Goldschmidt and under the name Emulgade KE3302 by Henkel, and arachidyl glucoside, for example in the form of a mixture of arachidic and behenic alcohols and arachidylglucoside sold under the name Montanov 202 5 by the company Seppic. According to a particular embodiment of the invention, the mixture of the alkylpolyglucoside as defined above with the corresponding fatty alcohol may be in the form of a self-emulsifying composition, as described for example in the document WO-A- 92/06778. The aqueous phase thereof may comprise a nonionic vesicular dispersion prepared according to known methods (Bangham, Standish and Watkins, J. Mol Biol 13, 238 (1965), FR 2 315 991 and FR 2 416 008).

  According to one particular form of the invention, fluid emulsions will be used.

  Fluid emulsion means an emulsion which does not appear in a solid form. Its viscosity can be measured using a Rhéomat 180 viscometer at 25 ° C. at a speed of rotation of 200 RPM after 30 seconds of rotation, with a measuring body 2, 3 or 4 and is preferably less than or equal to 20 Pa.s, more preferably less than 5 Pa.s, even more preferably less than or equal to 2 Pa.s, and more particularly less than or equal to 0.5 Pa.s.

  The compositions according to the invention find their application in a large number of treatments, in particular cosmetics, of the skin, lips and hair, including the scalp, in particular for the protection and / or care of the skin, lips and / or hair, and / or for makeup of the skin and / or lips.

  Another object of the present invention is the use of the compositions according to the invention as defined above for the manufacture of products for the cosmetic treatment of the skin, lips, nails, hair, eyelashes. , eyebrows and / or scalp, including skincare products, sunscreen products and make-up products.

  The cosmetic compositions according to the invention may, for example, be used as a skincare and / or sun protection product for the face and / or body of liquid to semi-liquid consistency, such as milks, more or less fluid creams. . They may optionally be packaged in aerosol and be in the form of foam or spray. The cosmetic compositions according to the invention may for example be used as a makeup product.

  The compositions according to the invention in the form of vaporizable fluid lotions according to the invention are applied to the skin or the hair in the form of fine particles by means of pressurizing devices. The devices according to the invention are well known to those skilled in the art and include non-aerosol pumps or "atomizers", aerosol containers comprising a propellant and aerosol pumps using compressed air as a propellant. These are described in US Patents 4,077,441 and 45 US 4,850,517 (forming an integral part of the content of the description).

  The aerosol-conditioned compositions according to the invention generally contain conventional propellants such as, for example, hydrofluorinated compounds, dichlorodifluoromethane, difluoroethane, dimethyl ether, isobutane, n-butane, propane and trichlorofluoromethane. They are present preferably in amounts ranging from 15 to 50% by weight relative to the total weight of the composition.

  Concrete, but not limiting, examples illustrating the invention will now be given.

  Synthesis Examples EXAMPLE 1 Preparation of a Poly (ethylene-ethyl) -starch-block copolymer (acrylic acrylonate) of type (2b) by synthesis of a Polvo-styrene-block-polv diblock copolymer (acrvlate) of ethyl) of Mn 2000-block-42000 (q / mole) and then hydrolyzed to 75% of ethyl acrvlate ester groups.

  Step 1a: Preparation of a first block of polystyrene with a theoretical molecular weight of about 2000 g / mol

  3000 g of water, 17.6 g of sodium dodecyl sulphate and 0.290 g of sodium carbonate Na 2 CO 3 are introduced into the reactor at ambient temperature. The resulting mixture is stirred for 30 minutes under nitrogen. The temperature is then raised to 75 ° C., then a mixture 1 comprising: 10.00 g of styrene (St), 0.200 g of methacrylic acid (AMA), and 10.42 g of xanthate (CH 3) are added. (CO2CH3) CH-S (C = S) OCH2CH3.

  The mixture is heated to 85 ° C., then a solution of 1.19 g of sodium persulfate Na 2 S 2 O 8 solubilized in 20.0 g of water is introduced.

  After 5 minutes, the addition of a mixture 2 comprising: 90.0 g of styrene (St) and 1.80 g of methacrylic acid (AMA) is begun.

  The addition is continued for 60 minutes. After complete addition of the various ingredients, the copolymer emulsion obtained is maintained at 85 ° C. for one hour.

  A sample (5 g) is then taken and analyzed by steric exclusion chromatography (SEC) in THF. Its measured average molecular weight Mn is equal to 2000 g / mol in polystyrene equivalents (calibration by linear polystyrene standards). Its polymolecularity index Mw / Mn is equal to 2.0.

  An analysis of the sample by gas chromatography reveals that the conversion of the monomers is greater than 99%.

  Step lb: Growth of a second block of poly (ethyl acrylate) with a theoretical molecular weight of about 42000 q / mol to obtain a polystyrene-blockpoly diblock copolymer (ethyl acrylonate)

  Starting from the emulsion copolymer obtained previously in step la after taking 5 g for analysis and without stopping the heating. 1.19 g of Na 2 S 2 O 8 sodium persulfate diluted in 50.0 g of water are continuously introduced for three hours.

  Simultaneously for three hours, a mixture 3 comprising: 200.0 g of water, 2.20 g of sodium carbonate Na 2 CO 3 and 50 4.40 g of sodium dodecyl sulphate are added at 85 ° C.

  Simultaneously, a mixture 4 comprising: 2100 g of ethyl acrylate (EA) and 42.0 g of methacrylic acid (AMA) 44 55 After complete addition of the various ingredients, the copolymer emulsion obtained is maintained at 85 ° C. for one hour. 4.40 g of tert-butylbenzyl peroxide are then introduced all at once and the addition of a mixture comprising: 2.20 g of erythorbic acid - 50.0 g of water is started.

  The addition is continued for 60 minutes. After complete addition of the various ingredients, the emulsion is cooled to -25 C for one hour. A sample (5 g) is then taken and analyzed by steric exclusion chromatography (SEC) in THF.

  Its measured average molecular weight Mn is equal to 41000 g / mol in polystyrene equivalents (calibration by linear polystyrene standards). Its polymolecularity index Mw / Mn is equal to 6.

  Analysis of the sample by gas chromatography reveals that the conversion of the monomers is greater than 99.8%. The product obtained is a dispersion in water of the copolymer (latex), dry extract of about 41%.

  Step II: Partial Hydrolysis (75% Targeted) of the Poly (ethyl acrylate) Block of the Copolymer Obtained Previously in Step Ib to Obtain the Polystyrene-Block-Poly Diblock (Ethyl Acrylate -Sodium Sodium Salt) acrylic acid) of the type (2b)

  750 g of water, 250 g of 2-propanol and 1347 g of emulsion copolymer (ie 550 g of dry copolymer) obtained previously in step 1b are introduced into the reactor at ambient temperature. The resulting mixture is stirred for 15 minutes. The temperature is then raised to 75 ° C., then 678 g of sodium hydroxide (solution in water at 23.2% by weight) are added continuously over one hour. After 30 minutes of the start of the addition of sodium hydroxide, the addition is continued continuously over one hour of 12 g of hydrogen peroxide (30% solution). After complete addition of the various ingredients, the copolymer solution obtained is maintained at 75 ° C. for four hours and then cooled at 25 ° C. for one hour.

  The product recovered at the end of the reaction is a translucent gel in the water of dry extract of about 20%.

  The copolymer thus obtained exhibits the following characteristics: theoretical average molecular mass of block A: 2000 g / mol; theoretical theoretical molecular mass of block B: 30000 g / mol; proportion by weight of block B: 96%; proportion by weight of block A: 4% - Quantity by weight of units derived from ethyl acrylate in block B: 31%

Example 2

  Preparation of a diblock copolymer Polystyrene-block-poly (ethyl acrylate-sodium salt of acrylic acid) of type (1b) by synthesis of a diblock copolymer Polystyrene-block-poly (ethyl acrylate ) Mn target 5000-block-7000 (g / mole) and then hydrolyzed to 75% of the ester groups of ethyl acrylate.

  Step la: Preparation of a first block of polystyrene with a theoretical molecular weight of approximately 5000 g / mol 1000 g of water, 6.50 g of sodium dodecyl sulphate and 0 are introduced into the reactor at ambient temperature. 30 g of sodium carbonate Na2CO3. The resulting mixture is stirred for 30 minutes under nitrogen. The temperature is then raised to 75 ° C., then a mixture 1 comprising: 83.7 g of styrene (St), 1.67 g of methacrylic acid (AMA), and 17.4 g of xanthate ( CH3) (CO2CH3) CH-S (C = S) OCH2CH3.

  The mixture is heated to 85 ° C. and then a solution of 2.00 g of sodium persulfate Na 2 S 2 O 8 solubilized in 20.0 g of water is introduced.

  After 5 minutes, the addition of a mixture 2 comprising: 334.7 g of styrene (St) and 6.69 g of methacrylic acid (AMA) is started.

  The addition is continued for 60 minutes. After complete addition of the various ingredients, the copolymer emulsion obtained is maintained at 85 ° C. for one hour. A sample (5 g) is then taken and analyzed by steric exclusion chromatography (SEC) in THF. Its measured average molecular weight Mn is equal to 5800 g / mol in polystyrene equivalents (calibration by linear polystyrene standards). Its polymolecularity index Mw / Mn is equal to 1.9.

  An analysis of the sample by gas chromatography reveals that the conversion of the monomers is greater than 99%. Step lb: Growth of a second block of polv (ethyl acrylonate) with a theoretical molecular weight of about 7000 g / mol to obtain a diblock copolymer polystyrene-block-poly (ethyl acrylate), starting from the copolymer emulsion obtained previously in step la after having taken 5 g for analysis and without stopping the heating.

  2.00 g of sodium persulfate Na 2 S 2 O 8 diluted in 50.0 g of water are introduced continuously for three hours. Simultaneously for three hours, a mixture 3 comprising: 200.0 g of water, -1.00 g of sodium carbonate Na 2 CO 3 and 2.00 g of sodium dodecyl sulphate are added at 85 ° C. Simultaneously a mixture 4 comprising: 581.6 g of ethyl acrylate (EA), and 11.63 g of methacrylic acid (AMA). After complete addition of the various ingredients, the copolymer emulsion obtained is maintained at 85 ° C. C for an hour.

  Then 2.0 g of tert-butylbenzyl peroxide are introduced in one go and the addition of a mixture comprising: 1.00 g of erythorbic acid - 50.0 g of water is started.

  The addition is continued for 60 minutes. After complete addition of the various ingredients, the emulsion is cooled to -25 C for one hour.

  A sample (5 g) is then taken and analyzed by steric exclusion chromatography (SEC) in THF. Its measured average molecular weight Mn is equal to 12700 g / mol in polystyrene equivalents (calibration by linear polystyrene standards). Its polymolecularity index Mw / Mn is equal to 1.9.

  Analysis of the sample by gas chromatography reveals that the conversion of the monomers is greater than 99.8%.

  The product obtained is a dispersion in water of the copolymer (latex), dry extract of about 44%.

  Step II: Partial Hydrolysis (75% Targeted) of the Poly (ethyl acrylate) Block of the Copolymer Obtained Previously in Step 2 to Obtain the Polystyrene-Block-Poly Diblock (Ethyl Acrylate -Sodium Sodium Salt) acrylic acid) of type (1b).

  638 g of water, 212 g of 2-propanol and 1485 g of emulsion copolymer (ie 650 g of dry copolymer) obtained previously in step 1b are introduced into the reactor at ambient temperature. The resulting mixture is stirred for 15 minutes. The temperature is then raised to 75 ° C., and then 488 g of sodium hydroxide (solution in water at 23.2% by weight) are added continuously over an hour.

  After 30 minutes of the start of the addition of sodium hydroxide, the addition is continued continuously over one hour of 37 g of hydrogen peroxide (30% solution).

  After complete addition of the various ingredients, the copolymer solution obtained is maintained at 75 ° C. for four hours and then cooled to -25 ° C. for one hour.

  The product recovered at the end of the reaction is a translucent gel in the water of dry extract of about 18%.

  The copolymer thus obtained exhibits the following characteristics: theoretical average molecular mass of block A: 5000 g / mol; theoretical average molecular weight of block B: 5000 g / mol; proportion by weight of block B: 57%; proportion by weight of Block A: 43% - Quantity by weight of units derived from ethyl acrylate in Block B: 31%

  EXAMPLE 3 Preparation of a diblock copolymer Polystyrene-block-poly (acrylic acid ethyl acrylate) of type (2a) by synthesis of a diblock copolymer Polystyrene-block-poly (ethyl acrylate ) Mn referred to 2000-block-20000 (g / mole) and then hydrolyzed to 75% of the ester groups of ethyl acrylate Step la: Preparation of a first block of polystyrene theoretical molecular weight of about 2000 q / 2150 g of water, 6.00 g of sodium dodecyl sulphate and 0.650 g of sodium carbonate Na 2 CO 3 are introduced into the reactor at ambient temperature. The resulting mixture is stirred for 30 minutes under nitrogen. The temperature is then raised to 75 ° C., then a mixture 1 comprising: 18.2 g of styrene (St), 0.33 g of methacrylic acid (AMA), and 18.9 g of xanthate ( CH3) (CO2CH3) CH-S (C = S) OCH2CH3.

  The mixture is heated to 85 ° C. and then a solution of 2.16 g of sodium persulfate Na 2 S 2 O 8 solubilized in 20.0 g of water is introduced.

  After 5 minutes, the addition of a mixture 2 comprising: 163.6 g of styrene (St) and 3.30 g of methacrylic acid (AMA) is started.

  The addition is continued for 60 minutes. After complete addition of the various ingredients, the copolymer emulsion obtained is maintained at 85 ° C. for one hour.

  A sample (û5 g) is then taken and analyzed by steric exclusion chromatography (SEC) in THF. Its measured average molecular weight Mn is equal to 2000 g / mol in polystyrene equivalents (calibration by linear polystyrene standards). Its polymolecularity index Mw / Mn is equal to 2.1.

  An analysis of the sample by gas chromatography reveals that the conversion of the monomers is greater than 99%. Step lla: growth of a second block of polv (ethyl acrylonate) theoretical molecular weight of about 20000 g / mol to obtain a diblock copolymer polystyrene-block-poly (ethyl acrylate), starting from the copolymer in emulsion obtained previously in step la after having taken 5 g for analysis and without stopping heating. 2.16 g of Na 2 S 2 O 8 sodium persulfate diluted in 50.0 g of water are continuously fed for three hours. Simultaneously for three hours, a mixture 3 comprising: 200.0 g of water, 4.00 g of sodium carbonate Na 2 CO 3 and 8.00 g of sodium dodecyl sulphate are added at 85 ° C. Simultaneously a mixture 4 comprising: 1818 g of ethyl acrylate (EA) and 33.4 g of methacrylic acid (AMA). After complete addition of the various ingredients, the copolymer emulsion obtained is maintained at 85 ° C. C for an hour. Then 4.0 g of tert-butylbenzyl peroxide are introduced in one go and addition of a mixture comprising: 2.00 g of erythorbic acid - 50.0 g of water is started.

  The addition is continued for 60 minutes. After complete addition of the various ingredients, the emulsion is cooled to -25 C for one hour.

  A sample (5 g) is then taken and analyzed by steric exclusion chromatography (SEC) in THF. Its measured average molecular weight Mn is equal to 17500 g / mol in polystyrene equivalents (calibration by linear polystyrene standards). Its polymolecularity index Mw / Mn is equal to 2.9.

  An analysis of the sample by gas chromatography reveals that the conversion of the monomers is greater than 99.8%.

  The product obtained is a dispersion in water of the copolymer (latex), dry extract of about 44%. Step II: Partial Hydrolysis (at 75% Target) of the Poly (Acrylate) Block of the Copolymer Obtained Previously in Step 2 to Obtain the Polystyrene-Block-Poly Diblock (Ethyl Acrylate -Sodium Sodium Salt) acrylic acid) of type (2a1). 900 g of water, 300 g of 2-propanol and 1563 g of emulsion copolymer (ie 700 g of dry copolymer) obtained previously in step 1b are introduced into the reactor at ambient temperature. The resulting mixture is stirred for 15 minutes. The temperature is then raised to 75 ° C., then 822 g of sodium hydroxide (solution in water at 23.2% by weight) are added continuously over one hour.

  After 30 minutes of the beginning of the addition of sodium hydroxide, the addition is continued continuously over one hour of 25 g of hydrogen peroxide (30% solution).

  After complete addition of the various ingredients, the copolymer solution obtained is maintained at 75 ° C. for four hours and then cooled to -25 ° C. for one hour.

  The product recovered at the end of the reaction is a translucent gel in the water of dry extract of about 17%.

  The copolymer thus obtained has the following characteristics: theoretical average molecular mass of the block A: 2000 g / mol; theoretical average molecular weight of the block B: 14000 g / mol; proportion by weight of the block B: 90%; proportion by weight of the Block A: 10% - Quantity by weight of units derived from ethyl acrylate in Block B: 31%.

  EXAMPLE 4 Preparation of a diblock copolymer Polystyrene-block-poly (acrylic acid ethyl acrylate) of the type (2a) by synthesis of a diblock copolymer Polystyrene-block-poly (ethyl acrylate ) Mn referred to 2000-block-20000 (g / mole) and then hydrolyzed to 90% of the ester group of ethyl acrylate.

  Step la: Preparation of a first block of polystyrene with a theoretical molecular weight of approximately 2000 g / mol 2150 g of water, 6.00 g of sodium dodecyl sulphate and 0.650 g are introduced into the reactor at ambient temperature. sodium carbonate Na2CO3. The resulting mixture is stirred for 30 minutes under nitrogen. The temperature is then raised to 75 ° C., then a mixture 1 comprising: 18.2 g of styrene (St), 0.33 g of methacrylic acid (AMA), and 18.9 g of xanthate ( CH3) (CO2CH3) CH-S (C = S) OCH2CH3.

  The mixture is heated to 85 ° C. and then a solution of 2.16 g of sodium persulfate Na 2 S 2 O 8 solubilized in 20.0 g of water is introduced. After 5 minutes, the addition of a mixture 2 comprising: 163.6 g of styrene (St) and 3.30 g of methacrylic acid (AMA) is started.

  The addition is continued for 60 minutes. After complete addition of the various ingredients, the copolymer emulsion obtained is maintained at 85 ° C. for one hour.

  A sample (5 g) is then taken and analyzed by steric exclusion chromatography (SEC) in THF. Its measured average molecular weight Mn is equal to 2000 g / mol in polystyrene equivalents (calibration by linear polystyrene standards). Its polymolecularity index Mw / Mn is equal to 2.1.

  An analysis of the sample by gas chromatography reveals that the conversion of the monomers is greater than 99%. Step lb: growth of a second block of polv (ethyl acrylonate) theoretical molecular weight of about 20000 g / mol to obtain a diblock copolymer polystyrene-blockpoly (ethyl acrylate), starting from the emulsion copolymer obtained previously in step 1 after removing 5 g for analysis and without stopping heating.

  2.16 g of sodium persulfate Na 2 S 2 O 8 diluted in 50.0 g of water are introduced continuously for three hours. Simultaneously for three hours, a mixture 3 comprising: 200.0 g of water, -4.00 g of sodium carbonate Na 2 CO 3 and 8.00 g of sodium dodecyl sulphate are added at 85 ° C.

  Simultaneously, a mixture 4 is added comprising: 1818 g of ethyl acrylate (EA) and 33.4 g of methacrylic acid (AMA)

  After complete addition of the various ingredients, the copolymer emulsion obtained is maintained at 85 ° C. for one hour. Then 4.0 g of tert-butylbenzyl peroxide are introduced in one go and the addition of a mixture comprising: 2.00 g of erythorbic acid - 50.0 g of water is started.

  The addition is continued for 60 minutes. After complete addition of the various ingredients, the emulsion is cooled to 25 ° C. for one hour.

  A sample (5 g) is then taken and analyzed by steric exclusion chromatography (SEC) in THF. Its measured average molecular weight Mn is equal to 17500 g / mol in polystyrene equivalents (calibration by linear polystyrene standards). Its polymolecularity index Mw / Mn is equal to 2.9.

  Analysis of the sample by gas chromatography reveals that the conversion of the monomers is greater than 99.8%.

  The product obtained is a dispersion in water of the copolymer (latex), dry extract 40 of about 44%.

  Step II: Partial hydrolysis (90% aimed) of the poly (ethyl acrylate) block of the copolymer obtained previously in step 2 to obtain the diblock polystyrene-block-poly (ethyl acrylate-sodium salt of acrylic acid) of type (2a). 1209 g of water, 206 g of 2-propanol and 1670 g of emulsion copolymer (ie 700 g of dry copolymer) obtained previously in step 1b are introduced into the reactor at ambient temperature. The resulting mixture is stirred for 15 minutes. The temperature is then raised to 70 ° C., then 1038 g of sodium hydroxide (solution in water at 23.2% by weight) are added continuously over one hour.

  After 30 minutes of the beginning of the addition of sodium hydroxide, (c) the continuous addition over one hour of 27 g of hydrogen peroxide (30% solution) is begun. After complete addition of the various ingredients, the copolymer solution obtained is maintained at 70 ° C. for four hours. Then reaction mixture is cooled to -25 C for one hour.

  The product recovered at the end of the reaction is a translucent gel in the water of dry extract of about 17%.

  The copolymer thus obtained has the following characteristics: theoretical average molecular mass of the block A: 2000 g / mol theoretical theoretical molecular weight of the block B: 14000 g / mol; proportion by weight of the block B: 89%; proportion by weight of the Block A: 11% - Quantity by weight of units derived from ethyl acrylate in Block B: 13% Example 5:

  Preparation of a Polvo-styrene-block-polv diblock copolymer (acrylonate acrylonate acrylic acid) of the type (a) by synthesis of a diblock copolymer Polystyrene-block-poly (ethyl acrylate) of the Mn targets 1000-block-5600 (q / mole) and then hydrolyzed to 75% of the ester groups of ethyl acrylate.

  Step la: Preparation of a first block of polystyrene with a theoretical molecular mass of approximately 1000 μg / mol 2400 g of water, 13.0 g of sodium dodecyl sulphate and 0 are introduced into the reactor at ambient temperature. 60 g of sodium carbonate Na2CO3. The resulting mixture is stirred for 30 minutes under nitrogen. The temperature is then raised to 75 ° C., then a mixture 1 comprising: 61.0 g of styrene (St), 1.22 g of methacrylic acid (AMA), and 63.5 g of xanthate ( CH3) (CO2CH3) CH-S (C = S) OCH2CH3.

  The mixture is heated to 85 ° C. and then a solution of 7.26 g of sodium persulfate Na 2 S 2 O 8 solubilized in 20.0 g of water is introduced. After 5 minutes, the addition of a mixture 2 comprising: - 243.9 g of styrene (St) and - 4.88 g of methacrylic acid (AMA) is started.

  The addition is continued for 60 minutes. After complete addition of the various ingredients, the copolymer emulsion obtained is maintained at 85 ° C. for one hour.

  A sample (5 g) is then taken and analyzed by steric exclusion chromatography (SEC) in THF. Its measured average molecular weight Mn is equal to 45 960 g / mol in polystyrene equivalents (calibration by linear polystyrene standards). Its polymolecularity index Mw / Mn is equal to 2.1.

  An analysis of the sample by gas chromatography reveals that the conversion of the monomers is greater than 99%. Step lb: Growth of a second block of polv (ethyl acrylonate) with a theoretical molecular weight of about 5600 g / mol to obtain a diblock copolymer polystyrene-blockpoly (ethyl acrylate) of type (la), 50 part of the emulsion copolymer obtained previously in step la after having taken 5 g for analysis and without stopping the heating.

  7.26 g of sodium persulfate Na 2 S 2 O 8 diluted in 50.0 g of water are introduced continuously for three hours. Simultaneously for three hours, a mixture 3 comprising 200.0 g of water, 2.00 g of sodium carbonate Na 2 CO 3 and 4.00 g of sodium dodecyl sulphate is added at 85 ° C.. mixture 4 comprising: - 1695 g of ethyl acrylate (EA), and - 33.90 g of methacrylic acid (AMA)

  After complete addition of the various ingredients, the copolymer emulsion obtained is maintained at 85 ° C. for one hour. Then 4.0 g of tert-butylbenzyl peroxide are introduced in one go and the addition of a mixture comprising: 2.00 g of erythorbic acid - 50.0 g of water is started.

  The addition is continued for 60 minutes. After complete addition of the various ingredients, the emulsion is cooled to 25 ° C. for one hour.

  A sample (5 g) is then taken and analyzed by steric exclusion chromatography (SEC) in THF. Its measured average molecular weight Mn is equal to 5900 g / mol in polystyrene equivalents (calibration by linear polystyrene standards). Its polymolecularity index Mw / Mn is equal to 2.3.

  Analysis of the sample by gas chromatography reveals that the conversion of the monomers is greater than 99.8%.

  The product obtained is a dispersion in water of the copolymer (latex), dry extract of about 40%.

  Step II: Partial Hydrolysis (75% Targeted) of the Poly (ethyl acrylate) Block of the Copolymer Obtained Previously in Step Ib to Obtain the Polystyrene-Block-Poly Diblock (Ethyl Acrylate -Sodium Sodium Salt) acrylic acid) of type (1a).

  1200 g of water and 3070 g of emulsion copolymer (1200 g of dry copolymer) obtained previously in step 1b are introduced into the reactor at ambient temperature. The resulting mixture is stirred for 15 minutes. The temperature is then raised to 75 ° C., and then 1314 g of sodium hydroxide (solution in water at 23.2% by weight) are added continuously over an hour.

  After 30 minutes of the start of the addition of sodium hydroxide, the addition is continued continuously over one hour of 124 g of hydrogen peroxide (30% solution).

  After complete addition of the various ingredients, the copolymer solution obtained is maintained at 75 ° C. for four hours. The reaction mixture is then cooled at 25 ° C. for one hour.

  The product recovered at the end of the reaction is a translucent gel in the water of dry extract of about 18%.

  The copolymer thus obtained has the following characteristics: theoretical average molecular mass of the block A: 1000 g / mol; theoretical average molecular weight of the block B: 4000 g / mol; proportion by weight of the block B: 84%; proportion by weight of Block A: 16% - Quantity by weight of units derived from ethyl acrylate in Block B: 31%

Examples of composition

  The fluid oil-in-water emulsions b and c according to the invention are compared with respect to a composition obtained from a Diglycol / Cyclohexanedimethanol / Isophthalates / Sulfoisophthalates Copolymer emulsifier polymer and by high pressure homogenization. Phase Composition Formula a Formula b Formula c (outside the invention) A Diglycol / Cyclohexanedimethanol / Isophthalates / 2 - - Sulfoisophthalates Copolymer (AQ 38S from Eastman Kodak) Copolymer of Example 5 - 4.67 8.77 Copolymer of Example 1 - 2.76 2.76 Deionized water 22 22 22 Glycerol 6 6 6 Terephthalylidene Dicamphor Sulfonic Acid 1.5 1.5 1.5 Triethanolamine 0.26 0 0 B1 Octocrylene 10 10 10 Butyl Methoxy Dibenzoylmethane 3 3 3 Drometrizole trisiloxane 1 1 1 Ethylhexyl triazone 1 1 1 C12-C15 alcohol benzoate 6 6 6 B2 2-ethyl glycerol hexyl ether 0.75 0.75 0.75

  .................. Cyclohexa dimethylsiloxane 5 5 Antioxidant qsp qsp qsp C Ethanol 4.3 4.3 4.3 D Terpolymer methacrylic acid / methyl 0.5 -acrylate: ethoxylated dimethyl meta-isopropenyl benzyl isocyanate E Hydrophilic titanium dioxide (MIRASUN TiW60 6.35 - - supplied by the company Rhodia) Deionized water qs 100 qs 100 qs 100 F Triethanolamine 0.1 - OPERATIVE MODE: .. DTD: For formulas b and c according to the invention: The aqueous phase (A) containing all of its ingredients is heated to 85 ° C. in a water bath. The fat phase (B1) containing all of its ingredients is heated to 85 ° C. in a water bath. Cool to 50 C and add B2 to B1. Cooling to 25 ° C. is continued. With rotor-stator stirring, phase A is poured into phase B and homogenized for 10 minutes at 25 ° C. Phase C is added and homogenized. For Formula A outside the invention:

  The aqueous phase (A) containing all of its ingredients is heated to 85 ° C. in the water bath. The fat phase (B1) containing all of its ingredients is heated to 85 ° C. in a water bath. Cool to 50 C and add B2 to B1. Cooling continues to 25 C.

  The resulting preparation is sent to a high pressure homogenizer (HHP) set at 500 bar. Three successive passes are made, taking care to cool the mixture between each passage. Phase D is added, homogenized. The titanium dioxide of phase E is predispersed in the water of phase E. Phase E is added to the emulsion with stirring. Phase F is introduced so as to adjust the pH to the desired value. In vitro efficacy test:

  The average SPF of each formulation is measured according to the method of evaluation of the protection factor used is the in vitro method described by B. L. DIFFEY et al. in J. Soc. Cosmet. Chem. 40-127-133 (1989), which consists in determining the monochromatic protection factors every 5 nm in a wavelength range of 290 to 400 nm, and calculating therefrom the protection factor solar energy according to a given mathematical equation. Each test composition is applied to frosted quartz plates at a dose of 0.75 mg / cm 2 with 4 plates per test and 4 measurements per plate. The spectrophotometer used is Optometrics SPF 2900.

  Results: N Concentration in SPF concentration active matter deviation active ingredient copolymer copolymer type formulation of example 5 of the exemplel Formula reference 34 7 a Formula 1% 0 66 16, 5 / b ______________________________________________ ____________________________ Formula c 2% 0.5% 63 14 Emulsions b and c according to the invention containing the combination of the two diblock copolymers obtained without high pressure homogenizer (HPP) are fine and homogeneous and have a significantly higher SPF than that of the reference formula obtained by HPP. Example d: Photoprotective milk: Phase A: 48.25% Distilled water Glycerin 3% Preservative 0.2% Citric acid 0.27% Copolymer of type (1b) hydrolysed to 75% (25% acrylate of ethyl) 18.18% to 16.5% in MA Phase B: 12% Parleam oil Cyclohexadimethylsiloxane 8% Preservative 0.1% Octocrylene 7% Butyl methoxydibenzoylmethane 3% Phase B is added with vigorous stirring in phase A reduced by 40% water. These are added at the end of emulsification, by simple dilution.

  A highly fluid, sprayable, stable dispersion is obtained which is at least 2 months old and whose drop size is equal to 3 μm. Its viscosity measured at rheomat 180 at 25 ° C. at a rotational speed of the mobile 2 of 200 RPM is less than 0.018 Pa · s. 25

Claims (65)

  An oil-in-water cosmetic emulsion comprising in a physiologically acceptable medium: a) at least one continuous aqueous phase; b) at least one fatty phase dispersed in said aqueous phase comprising at least one polar oil; c) at least one lipophilic organic UV filter; d) at least at least one linear diblock copolymer (block A) - (blockB) in which - block A comprises at least units derived from styrene; - Block B comprises at least (a) units derived from acrylic acid in acid or salified form and (b) at least units derived from a C 1 -C 4 alkyl acrylate.   An emulsion according to claim 1, wherein said diblock copolymer is linear.   3. Emulsion according to claim 1 or 2, wherein said diblock copolymer is the proportion by weight of the block B with respect to the copolymer being greater than or equal to 50%.   4. Emulsion according to any one of claims 1 to 3, wherein the copolymer is characterized in that: - block A comprises at least 90% by weight of units derived from styrene based on the total weight of block A; block B is a statistical block comprising, with respect to the total weight of block B: (i) from 34 to 95% by weight of units derived from acrylic acid in acid form or in salified form, (ii) from 5 to 66% by weight of units derived from C1-C4 alkyl acrylate. the proportion by weight of block B with respect to the copolymer being greater than or equal to 50%.   5. Emulsion according to any one of claims 1 to 4, wherein the C 1 -C 4 alkyl acrylate is ethyl acrylate.   6. Emulsion according to any one of claims 1 to 5, characterized in that the block A and / or the block B comprises up to 10% by weight, in particular from 0.1 to 10% by weight and preferably up to 5%, in particular from 0.1 to 5% by weight of a hydrophilic ionic or nonionic comonomer relative to the total weight of block A or block B containing said hydrophilic comonomer.   7. Emulsion according to claim 6, wherein the hydrophilic comonomer is methacrylic acid in acid or salified form.   8. Emulsion according to any one of claims 1 to 7, wherein the diblock copolymer (block A) - (block B) is of type (1) in which the proportion by weight of block B with respect to the copolymer is between 50 and 85%.   9. Emulsion according to claim 8, wherein the copolymer is of the type (1 a) in which the proportion by weight of the block B with respect to the copolymer is greater than or equal to 75% by weight and preferably between 75 and 85% by weight. .   The emulsion of claim 8, wherein the copolymer is of type (1b) in which the proportion by weight of block B is less than 75% and preferably between 50% to 75% .50   11. The composition of claim 10, wherein the copolymer is of the type (2a) in which the proportion by weight of the block B relative to the copolymer is greater than or equal to 87% and less than 94%.   12. The emulsion of claim 11, wherein the copolymer is of the type (2b) in which the proportion by weight of the block B with respect to the copolymer is greater than or equal to 94%, in particular ranging from 94% to 97%.   13. Emulsion according to any one of claims 8 to 13, containing a mixture of at least one diblock copolymer of type (1) and at least one diblock copolymer of type (2).   14. Emulsion according to claim 14, containing a mixture of at least one diblock copolymer of type (Ia) and at least one diblock copolymer of type (2b) (BOL 55). 15   15. Emulsion according to any one of claims 1 to 14, wherein the diblock copolymer (block A) - (block B) is obtainable by a polymerization process comprising at least the following steps: step I): prepares: a diblock copolymer (block A) - (block B '), or - a triblock copolymer or architecture star (core) - [(block A) - (block B')] x where (core) - [(block B ') - (block A)] x where x is an average number greater than or equal to 2, where - block A comprises units derived from Styrene, and - block B' comprises units derived from a C1-C4 alkyl acrylate, step I ') optionally, for a triblock or star copolymer, breaks the bonds (core) - (block B') or (core) - (block A), so as to obtain a diblock copolymer (block A) - (block B '), step II) the block B' is hydrolyzed to a block B to obtain the diblock copolymer (block A) - (block B), the hydrolysis inducing if necessary for a triblock copolymer or star, a breakage of liaiso ns (core) - (block B ') or (core) - (block A), so as to obtain a diblock copolymer (block A) - (block B). 35   An emulsion according to any one of claims 1 to 15, wherein the diblock copolymer (block A) - (block B) is obtainable by a polymerization process comprising at least the following steps: I) preparing a diblock copolymer (block A) - (block B ') by a process comprising the following intermediate steps la) and lb): a) preparing a first block A, by bringing into contact: - nT moles of a transfer comprising a single transfer group - nA moles of styrene or a monomer mixture comprising at least 90% by weight of styrene and where nA / nT> 5 and preferably <5000; and optionally a free radical initiator lb), a second block B 'is prepared to obtain a diblock copolymer (block A) - (block B'), by placing the block A in the preceding stage in the presence of: nB moles of a hydrolyzable C1-C4 alkyl acrylate or a mixture of monomers comprising at least 90% by weight of a C1-C4 alkyl acrylate such that nB / nT> 5 and preferably <5000; - and optionally a free radical initiator, 25Il) hydrolysis of the B 'block is then carried out at a molar ratio T of between 0.4 and 0.96 to obtain said diblock copolymer (block A) - (block B).   17. Emulsion according to claim 15 or 16, characterized in that an additional step III) is carried out during and / or after step II) of deactivation of transfer groups carried by macromolecular chains and / or of purification of the copolymer. diblock (block A) - (block B) and / or destruction of byproducts of hydrolysis and / or deactivation.   18. Emulsion according to any one of claims 15 to 17, characterized in that step I) is carried out by emulsion polymerization in water.   19. Emulsion according to any one of claims 15 to 18, characterized in that the degree of hydrolysis T is between 0.7 and 0.8; preferably T is 0.75.   20. Emulsion according to any one of claims 15 to 19, characterized in that the block A and / or the block B 'or the block B comprises 0.1 to 10% by weight and preferably 0.1 at 5% by weight of a hydrophilic ionic or nonionic comonomer relative to the total weight of block A, block B or block B 'containing said hydrophilic comonomer.   An emulsion according to claim 20, wherein the hydrophilic comonomer is methacrylic acid in acidic or salified form.   22. Emulsion according to one of claims 15 to 21, characterized in that the C1-C4 alkyl acrylate is ethyl acrylate.   23. Emulsion according to one of claims 15 to 22, characterized in that the diblock copolymer (block A) - (block B) is of type (1) in which - the proportion by weight of block B with respect to the copolymer is between 50 and 85% and - its theoretical average molecular weight is less than 13000 g / mol. 35   24. A composition according to claim 23, characterized in that the diblock copolymer (block A) - (block B) is of the type (la) in which - the proportion by weight of the block B with respect to the copolymer is greater than or equal to 75 % and preferably between 75 and 85% by weight and - its theoretical average molecular weight is less than 8000 g / mol and preferably 40 between 2000 and 8000 g / mol.   25. Composition according to claim 24, characterized in that the diblock copolymer (block A) - (block B) is of the type (lb) in which - the proportion by weight of the block B with respect to the copolymer is less than 75% and preferably between 50 and 75% by weight and its theoretical average molecular weight is greater than or equal to 8000 g / mol and preferably between 8000 and 13000 g / mol.   26. Composition according to one of claims 15 to 22, characterized in that the diblock copolymer (block A) - (block B) is of the type (2) in which: the proportion by weight of the block B with respect to The copolymer is greater than or equal to 85% and its theoretical average molecular weight is greater than or equal to 13000 g / mol.   27. Composition according to claim 26, characterized in that the diblock copolymer (block A) - (block B) is of the type (2a) in which: the proportion by weight of the block B with respect to the copolymer is greater than or equal to 87% and less than 94%; its theoretical average molecular weight is between 13000 g / mol and 20000 g / mol.   28. Composition according to claim 26, characterized in that the diblock copolymer (block A) - (block B) is of the type (2b) in which: the proportion by weight of the block B with respect to the copolymer is greater than or equal to 94%, especially ranging from 94 to 97% and - its theoretical average molecular weight is greater than or equal to 20000 g / mol and preferably between 20000 and 50000 g / mol, and more preferably between 25000 and 50000 g / mol, and even more preferably between 28,000 and 40,000 g / mol,   29. Emulsion according to any one of claims 23 to 28, containing a mixture of at least one diblock copolymer of type (1) and at least one diblock copolymer of type (2).   30. Emulsion according to claim 29, containing a mixture of at least one diblock copolymer of type (Ia) and at least one diblock copolymer of type (2b).   31. Emulsion according to any one of claims 1 to 30, wherein the diblock copolymer or copolymers are present in concentrations of active material ranging from 0.01 to 5% by weight and preferably from 0.05 to 2% by weight. weight relative to the weight of the composition.   32. Emulsion according to any one of claims 1 to 31, wherein the lipophilic organic UV filters are chosen from cinnamic derivatives; anthranilates; salicylic derivatives, dibenzoylmethane derivatives, camphor derivatives; benzophenone derivatives; R, 13-diphenylacrylate derivatives; triazine derivatives; benzotriazole derivatives; benzalmalonate derivatives; benzimidazole derivatives; imidazolines; bis-benzoazolyl derivatives; paminobenzoic acid derivatives (PABA); benzoxazole derivatives; filter and silicone filters such as those described; dimers derived from α-alkylstyrene and mixtures thereof.   An emulsion according to claim 32, wherein the lipophilic organic UV filters are selected from ethylhexyl methoxycinnamate, ethyl hexyl salicylate, homosalate, octocrylene, butyl methoxy, dibenzoylmethane, phenylbenzimidazole, sulfonic acid, 45, disodium, phenyl, dibenzimidazole, tetrasulfonate, benzophenone, 2- (4-diethylamino), and N-hexyl 2-hydroxybenzoyl) benzoate. 4-Methylbenzylidene camphor, bis-ethylhexyloxyphenol methoxyphenyl triazine 50 ethylhexyl triazone, diethylhexyl butamido triazone, 2,4,6-tris (4-amino benzalmalonate dineopentyl) -s-triazine 2,4,6-tris- (4 amino benzalmalonate diisobutyl) -s-triazine. Drometrizole Trisiloxane 45Polysilicone-15 1,1-dicarboxy (2,2'-dimethylpropyl) -4,4-diphenylbutadiene 2,4-bis- [5-1 (dimethylpropyl) benzoxazol-2-yl- (4-phenyl) ) -imino] -6 (2-ethylhexyl) imino-1,3,5-triazine and mixtures thereof.   34. Emulsion according to any one of claims 1 to 33, wherein the lipophilic organic photoprotective agents are present in proportions ranging from 0.01 to 20% by weight relative to the total weight of the composition, and preferably ranging from , 1 to 10% by weight relative to the total weight of the composition.   35. Emulsion according to any one of claims 1 to 34, characterized in that it additionally contains at least one insoluble inorganic UV filter and / or an insoluble organic UV filter.   The emulsion of claim 35, wherein the inorganic UV filters are metal oxide pigments.   37. The emulsion of claim 36, wherein the metal oxide pigments are selected from titanium, zinc, iron, zirconium, cerium oxides or mixtures thereof.   38. Emulsion according to claim 36 or 37, wherein the metal oxide pigments are coated or uncoated. 25   An emulsion according to any one of claims 38 to 40, wherein the metal oxide pigments are metal oxide particles having an average particle size of less than or equal to 500 nm,   40. The emulsion of claim 39, wherein the average particle size is between 5 nm and 500 nm.   41. Emulsion according to claim 40, wherein the average elementary particle size is between 10 nm and 100 nm. 35   42. An emulsion according to claim 41, wherein the average particle size is between 15 nm and 50 nm.   43. An emulsion according to any one of claims 36 to 42, wherein the metal oxide pigments are selected from titanium oxide pigments, coated or uncoated.   44. Emulsion according to any one of claims 1 to 43, wherein the inorganic UV filters represent from 0.5 to 40%, preferably from 1 to 30%, of the total weight of the composition.   45. The emulsion according to claim 35, wherein the insoluble organic UV screening agent (s) is (are) chosen from those polyvalent metal salts of sulphonated or carboxylated organic filters. 50   An emulsion according to claim 45, wherein the insoluble UV filters are selected from polyvalent metal salts of sulfonated benzylidenecamphor derivatives; polyvalent metal salts of sulfonated benzimidazole derivatives and polyvalent metal salts of cinnamic acid derivatives. 5   47. Emulsion according to claim 35, wherein the insoluble organic UV screening agent (s) is (are) chosen from oxalanilide, triazine, benzotriazole, vinyl amide, cinnamide, benzazole, benzofuran, arylvinylidene ketone, acrylonitrile amide and acrylonitrile sulfonamide. , acrylonitrile carbamate or phenylene-bis-benzoxazinone.   48. The emulsion according to claim 47, wherein the insoluble organic UV screening agent (s) is chosen from methylene-bis (hydroxyphenylbenzotriazole) derivatives having the following structure: ## STR2 ## in which R 8 and R 9, which may be identical or different, each represent an alkyl radical. C1-C18 may be substituted with one or more radicals selected from C1-C4 alkyl, C5-C12 cycloalkyl or aryl.   49. An emulsion according to claim 50, wherein the insoluble organic UV filter is 2,2'-methylene-bis- [6- (2H-benzotriazol-2-yl) -4- (1,1,3,3- tetramethylbutyl) phenol].   50. Emulsion according to any one of claims 35, 45 to 49, wherein the insoluble organic UV filter or filters are in the form of particles of average size ranging from 10 nm to 5pm.   51. An emulsion according to claim 49, wherein the average size varies from 10 nm to 2 μm, and in particular from 20 nm to 1.5 μm, and more particularly from 30 nm to 1.0 μm.   52. An emulsion according to any one of claims 35, 45 to 51, wherein the insoluble organic UV filter (s) is (are) capable of being obtained by a method of grinding an insoluble organic UV filter in the form of coarse particles. in the presence of a surfactant.   53. The emulsion according to claim 52, wherein the surfactant is selected from alkylpolyglucosides of the structure CnH 2n + 1O (C6H1005) XH wherein n is an integer of 8 to 16 and x is the average degree of polymerization of the unit (C6H1005) and ranges from 1.4 to 1.6.   54. Emulsion according to claim 52 or 53, wherein the surfactant is used at a concentration of from 1 to 50% by weight and more preferably from 5 to 40% by weight relative to the insoluble filter.   55. Emulsion according to any one of claims 35, 45 to 54, wherein the insoluble organic UV screening agent (s) is present at a total concentration of between approximately 0.1 and 25% by weight, and preferably between 0.2 and About 20% by weight, based on the total weight of the composition.   56. An emulsion according to any one of claims 1 to 55, further comprising at least one complementary organic photoprotective agent active in the UVA and / or the hydrophilic UVB. 20 45   57. Emulsion according to claim 56, wherein the one or more hydrophilic photoprotective agents are chosen from Terephthalylidene Dicamphor Sulfonic Acid Benzophenone-4 Phenylbenzimidazole Sulfonic Acid Disodium Phenyl Dibenzimidazole Tetrasulfonate and mixtures thereof.   58. An emulsion according to claim 56 or 57, wherein the hydrophilic photoprotective agent (s) are present in the compositions according to the invention in proportions ranging from 0.01% to 20% by weight relative to the total weight of the composition, and from preferably ranging from 0.1 to 10% by weight relative to the total weight of the composition.   An emulsion according to any one of the preceding claims, wherein the oil or polar oils have an oil / water interfacial tension measured at 25 ° C. of less than 35 mN m -1.   An emulsion according to any one of the preceding claims, wherein the oil or polar oils are preferably present in concentrations ranging from 3 to 50% and preferably from 5 to 40% by weight% by weight with respect to total weight of the composition.   61. Emulsion according to any one of the preceding claims, further comprising at least one self-tanning agent.   62. Emulsion according to any one of the preceding claims, further comprising at least one cosmetic adjuvant chosen from the non-polar oils defined in the preceding claims, organic solvents, ionic or nonionic thickeners, hydrophilic or lipophilic. , softeners, humectants, opacifiers, stabilizers, emollients, silicones, anti-foam agents, perfumes, preservatives, anionic, cationic, nonionic, zwitterionic or amphoteric surfactants, actives, fillers , polymers, propellants, alkalinizing or acidifying agents or any other ingredient usually used in the cosmetic and / or dermatological field.   63. Emulsion according to any one of the preceding claims, characterized in that it is fluid.   64. Use of an emulsion as defined in any one of the preceding claims for the manufacture of products for the cosmetic treatment of the skin, lips, nails, hair, eyelashes, eyebrows and / or scalp including skin care products, sunscreen products and make-up products.   65. Cosmetic use of at least one diblock copolymer as defined according to any one of the preceding claims in an oil-in-water emulsion, in particular a fluid, comprising in a physiologically acceptable medium a) at least at least one fatty phase comprising at least minus one polar oil, b) at least one lipophilic organic UV filter and c) optionally at least one inorganic insoluble UV filter and / or an organic UV filter, in order to improve the cosmetic properties and / or to improve the stability of said emulsion and / or in order to increase the sun protection factor (SPF) and / or to improve the water retention of the photoprotective power.