Device and method for obtaining a nanoemulsion and resulting nanoemulsion

Abstract

The present invention relates to a device (10) and a method for preparing nanoemulsions, in particular cosmetic, comprising droplets having a narrow size distribution. The invention also relates to the nanoemulsions obtained.

Description

[0001] DESCRIPTION

[0002] Device and method for obtaining nanoemulsion

[0003] The present invention relates to a device for preparing a nanoemulsion from a first and a second immiscible liquid phase, the device comprising a first stretch mixer adapted to allow a liquid flow to pass through it; said first mixer comprising: an inlet zone; an outlet zone; and at least one microchannel fluidly connecting the inlet and outlet zones; the inlet zone, the outlet zone, and the at least one microchannel having, respectively, a first, a second, and a third section perpendicular to the flow, a ratio between the third section and each of the first and second sections being less than or equal to 1 / 3. A device comprising a stretch mixer is notably known from US patent 5451106, for mixing polymers having different viscosities.

[0004] An elongation mixer allows, in particular, the production of emulsions from a two-phase mixture that include droplets with a narrow size distribution, including nanoemulsions. The term "nanoemulsion" preferably refers to a direct (i.e., oil-in-water or O / W) or inverse (i.e., water-in-oil or W / O) emulsion in which the dispersed phase has a size of less than 1 µm.

[0005] In the cosmetics industry, it is particularly advantageous to offer such oil-in-water or water-in-oil nanoemulsions, especially in cosmetics for alcohol-free perfumes, sunscreens, makeup, skincare, and haircare products, as well as baby hygiene products; and in household cleaning and textile care. However, existing methods are not suitable for the industrial-scale production of this type of nanoemulsion.

[0006] To this end, the invention relates to a preparation device of the aforementioned type, which further comprises: a first and a second fluid conduit; a first and a second reserve compartment; and a circulation pump; a first end of the first and second fluid conduits opening respectively into the inlet and outlet zones of the first mixer; a second end of the first and second fluid conduits opening respectively into the first and second reserve compartments; the circulation pump being disposed on one of the first and second fluid conduits. According to other advantageous aspects of the invention, the preparation device comprises one or more of the following features, taken individually or in any technically feasible combination:

[0007] - the first mixer further comprises a convergence zone and a divergence zone, arranged between at least one microchannel and, respectively, the inlet zone and the outlet zone; the convergence zone having a decreasing cross-section in the direction of the flow, between the first and third sections; the divergence zone having an increasing cross-section in the direction of the flow, between the third and second sections;

[0008] - the first mixer comprises a plurality of microchannels, fluidly connecting the inlet and outlet areas, a ratio between a section of each of said microchannels and each of the first and second sections being preferably less than or equal to 1 / 100;

[0009] - the circulation pump is located on the first fluid conduit;

[0010] - the device also includes fluidic communication between the first and second reserve compartments, away from the first mixer;

[0011] - the device further comprises: a second stretch mixer, said second mixer comprising: an inlet zone; an outlet zone; and at least one microchannel, fluidically connecting the inlet and outlet zones; and a third and a fourth fluid conduit; a first end of the third and fourth fluid conduits opening respectively onto the inlet zone and the outlet zone of the second mixer; a second end of the third and fourth fluid conduits opening respectively onto the second and the first reserve compartments; the circulation pump being disposed on one of the third and fourth fluid conduits, preferably on the third fluid conduit;

[0012] - the device further comprises at least one first valve, disposed on one of the first and second fluid conduits; and at least one second valve, disposed on one of the third and fourth fluid conduits; the device being configured so that when one of the first and second valves is open, the other of the first and second valves is closed;

[0013] - the device further comprises: a fluid circuit; and a third and a fourth three-way valve; the fluid circuit comprising a first, a second and a third branch, arranged in parallel between the third and fourth valves; the circulation pump and the first stretch mixer being arranged on the first branch of the circuit; the first and second reserve compartments being arranged respectively on the second and third branches of the circuit; the first reserve compartment comprising: a first outlet, corresponding to the second end of the first fluid conduit and oriented towards the third valve; and a first inlet, oriented towards the fourth valve; the second reserve compartment comprising: a second inlet, corresponding to the second end of the second fluid conduit and oriented towards the fourth valve; and a second outlet, oriented towards the third valve;the device being configured so that, in a first configuration of the third and fourth valves, the first fluid conduit extends between the first outlet of the first compartment and the first mixer; and the second fluid conduit extends between the first mixer and the second inlet of the second compartment;

[0014] - the device is configured so that, in a second configuration of the third and fourth valves, a fifth fluid conduit extends between the second outlet of the second compartment and the first mixer; and a sixth fluid conduit extends between the first mixer and the first inlet of the first compartment.

[0015] The invention further relates to a method for implementing a preparation device as described above, the method comprising the following steps:

[0016] - introduction, into the first reserve compartment, of a mixture of a first and a second immiscible liquid phase; then

[0017] - implementation of several successive cycles, each cycle comprising the following steps: circulation of a mixture flow in the first conduit, between the first reserve compartment and the first mixer; then circulation of said flow in the second conduit, between the first mixer and the second reserve compartment; then transfer of the mixture from the second compartment to the first reserve compartment; so as to obtain a nanoemulsion comprising droplets of second liquid phase suspended in the first liquid phase, a droplet diameter being preferably less than 1 pm.

[0018] According to one embodiment, the process is such that the step of transferring the mixture from the second compartment to the first reserve compartment includes: a circulation of a flow of the mixture in the third conduit, between the second reserve compartment and the second mixer; then circulation of said flow in the fourth conduit, between the second mixer and the first reserve compartment.

[0019] According to another embodiment, the process is such that the step of transferring the mixture from the second compartment to the first reserve compartment includes: a circulation of a flow of the mixture in the fifth conduit, between the second compartment and the first mixer; then a circulation of said flow in the sixth conduit, between the first mixer and the first compartment.

[0020] The invention further relates to a nanoemulsion that can be obtained by the process according to the invention.

[0021] Such a nanoemulsion preferably comprises an aqueous phase, an oily phase, and at least one anionic or non-ionic surfactant.

[0022] Preferably, the aqueous phase comprises water and preferably also at least one water-soluble organic solvent, preferably selected from polyols, specifically glycerin (or glycerol) and maltodextrins, and / or the oily phase comprises at least one vegetable oil and / or at least medium-chain triglycerides, preferably the vegetable oil being selected from coconut oil, palm kernel oil, sweet almond oil, olive oil, apricot oil, linseed oil, sunflower oil, rapeseed oil, grapeseed oil, argan oil, sesame oil, avocado oil, jojoba oil, safflower seed oil, and soybean oil, and / or the nonionic surfactant being selected from phosphoglycerides and polyglycerol fatty acid esters, preferably chosen from among phosphatidylcholines (lecithins), hydrogenated or not, polyglyceryl-10 stearate, polyglyceryl-4 oleate,polyglyceryl-3 ricinoleate and mixtures thereof, and / or wherein the anionic surfactant is selected from sulfate surfactants, isethionate surfactants, sulfoacetate surfactants and sarcosinate surfactants, preferably from sodium coco sulfate, sodium cocoyl isethionate, sulfated castor oil, sodium lauryl sulfoacetate, sodium lauroyl sarcosinate and mixtures thereof.

[0023] The invention will be better understood upon reading the following description, given solely by way of non-limiting example and made with reference to the drawings in which:

[0024] - Figure 1 is a schematic representation of a preparation device according to a first embodiment of the invention, comprising an elongation mixer;

[0025] - Figure 2 is a schematic representation of the mixer of the device in Figure 1;

[0026] - Figure 3 is a schematic representation of a preparation device according to a second embodiment of the invention; and

[0027] - Figure 4 is a schematic representation of a preparation device according to a third embodiment of the invention.

[0028] Device

[0029] Figures 1, 3, and 4 show devices 10, 110, and 210, respectively, according to a first, second, and third embodiment of the invention. Devices 10, 110, and 210 will be described concurrently below, with common elements designated by the same reference numbers.

[0030] The device 10, 1 10, 210 comprises: a first elongation mixer 12; a first 14, 1 14, 214 and a second 16, 116, 216 fluid conduits; a first 18, 1 18, 218 and a second 20, 120, 220 reserve compartments; and a circulation pump 22, 122.

[0031] The device 110 of figure 3 further includes a second elongation mixer 124.

[0032] The first mixer 12 is shown schematically in Figure 2 and will be described below as "mixer 12". The second mixer 124 in Figure 3 is considered to be identical to the first mixer 12.

[0033] The stretch mixer 12 is suitable for a flow 26 of liquid through it and comprises: an inlet zone 30; an outlet zone 32; and at least one microchannel 34, fluidly connecting the inlet zone 30 and outlet zone 32.

[0034] The inlet zone 30, the outlet zone 32 and the microchannel 34 have respectively a first 36, a second 38 and a third 40 sections perpendicular to the flow 26.

[0035] The third section 40 is significantly smaller than the first 36 and second 38 sections. More precisely, a ratio between the third section 40 and each of the first 36 and second 38 sections is less than or equal to 1 / 3, preferably less than or equal to 1 / 5, and more preferably less than or equal to 1 / 6.

[0036] Preferably, said ratio between the third section 40 and each of the first 36 and second 38 sections is greater than or equal to 1 / 5,000, more preferably greater than or equal to 1 / 1,500, still more preferably greater than or equal to 1 / 750.

[0037] As an example, each of the first 36 and second 38 sections is between 1 mm and 224 mm; and the third 40 section is between 0.15 mm and 0.3 mm.

[0038] According to one embodiment, the first 36 and second 38 sections are substantially identical.

[0039] Consider a liquid mixture 42 in the form of an emulsion, composed of a first 44 and a second 46 immiscible liquid phases. Droplets 48, 49 of the second liquid phase are distributed within the first liquid phase 44.

[0040] The mixture 42 located in the inlet zone 30 is considered to contain initial droplets 48 with a first maximum size. By moving a flow 26 of the mixture 42 between the inlet zone 30 and the outlet zone 32, the stretch mixer 12 is able to break down the initial droplets 48 into second droplets 49. These second droplets 49 have a second maximum size, smaller than the first maximum size.

[0041] More specifically, the passage of the flow 26 through the microchannel 34 exerts on the first droplets 48 a tensile stretch in the direction of the flow 26 and a compression in the direction perpendicular to the flow, leading to their fragmentation into second droplets 49 of smaller size.

[0042] According to the embodiment shown, the mixer 12 further comprises a convergence zone 50 and a divergence zone 52.

[0043] The convergence zone 50 is located between the inlet zone 30 and the microchannel 34. The convergence zone 50 has a decreasing section in the direction of the flow 26, between the first 36 and the third 40 sections.

[0044] The divergence zone 52 is arranged between the microchannel 34 and the outlet zone 32. The divergence zone 52 has a section increasing in the direction of the flow, between the third 40 and the second 38 sections.

[0045] According to an embodiment not shown, the mixer 12 comprises a plurality of microchannels 34, fluidly connecting the inlet 30 and outlet 32 ​​zones. For example, the mixer comprises a number of microchannels between 1 and 100.

[0046] According to such an embodiment, a section of each of the microchannels is significantly smaller than the first 36 and second 38 sections of the entry 30 and exit 32 zones.

[0047] Preferably, a ratio between the cross-section of each of said microchannels and each of the first 36 and second 38 sections is less than or equal to 1 / 100, more preferably less than or equal to 1 / 500.

[0048] Preferably, said ratio between the cross-section of each of said microchannels and each of the first 36 and second 38 sections is greater than or equal to 1 / 5,000, more preferably greater than or equal to 1 / 1,500, more preferably greater than or equal to 1 / 750.

[0049] The 10, 1 10, 210 device will now be described in its entirety.

[0050] A first end 54, 56 of the first 14, 114, 214 and second 16, 1 16, 216 fluid conduits opens respectively into the inlet zone 30 and the outlet zone 32 of the first mixer 12. A second end 58, 60 of the first 14, 1 14, 214 and second 16, 116, 216 fluid conduits opens respectively into the first 18, 1 18, 218 and the second 20, 120, 220 reserve compartments.

[0051] The circulation pump 22, 122 is located on one of the first 14, 114, 214 and second 16, 116, 216 fluid lines. Preferably, said pump is located on the first fluid line 14, 114, 214, i.e. upstream of the first mixer 12, to avoid cavitation phenomena in said first mixer.

[0052] Preferably, the 22,122 circulation pump is a continuous drive pump, of the gear pump type.

[0053] Device 10 in Figure 1 will now be described more specifically.

[0054] The device 10 of figure 1 includes a fluidic communication 62 between the first 18 and second 20 reserve compartments, away from the first mixer 12. For example, as in the embodiment shown, the device 10 includes a single reservoir 64, comprising: an inlet, corresponding to the second end 60 of the second conduit 16, and an outlet, corresponding to the first end 58 of the first conduit 14.

[0055] In the embodiment of Figure 1, the first 18 and second 20 reserve compartments are considered to be the parts of the tank 64 respectively close to the outlet 58 and the inlet 60 of said tank; and the fluidic communication 62 corresponds to a junction between said parts of the tank.

[0056] According to one embodiment, the inlet 60 of the tank 64 is located higher than the outlet 58 of said tank, the first reserve compartment 18 being located below the second reserve compartment 20.

[0057] According to an alternative embodiment (not shown) of device 10, said device comprises several mixers 12 arranged in parallel between the pump 22 and the reservoir 64.

[0058] Device 110 in Figure 3 will now be described more specifically.

[0059] In addition to the second mixer 124 mentioned previously, substantially identical to the first mixer 12, the device 110 of figure 3 includes a third 166 and a fourth 168 fluid conduits.

[0060] A first end 170, 172 of the third 166 and fourth 168 fluid conduits opens respectively into the inlet zone 30 and the outlet zone 32 of the second mixer 124; a second end 174, 176 of the third and fourth fluid conduits opens respectively into the second 120 and the first 118 reserve compartments.

[0061] The circulation pump 122 is disposed on both one of the first 114 and second 116 fluid conduits and on one of the third 166 and fourth 168 fluid conduits.

[0062] Preferably, the circulation pump 122 is located on the third fluid line 166, upstream of the second mixer 124. Furthermore, in the device 110 of Figure 3, the first 118 and second 120 reserve compartments are separate from each other. In particular, the first compartment 118 opens into a first manifold 178, corresponding to the second ends 58 and 176 of the first 114 and fourth 168 fluid lines. Moreover, the second compartment 120 opens into a second manifold 180, corresponding to the second ends 60 and 174 of the second 116 and third 166 fluid lines. The first 118 and second 120 reserve compartments have no fluid communication between them except through the first 178 and second 180 manifolds.

[0063] Furthermore, the device 110 of Figure 3 includes at least one first valve 182, 183 located on one of the first 114 and second 116 fluid conduits; and at least one second valve 184, 185 located on one of the third 166 and fourth 168 fluid conduits. Preferably, the first 182, 183 and second 184, 185 are two-way valves. Preferably, the device 110 is configured such that when one of the first and second valves is open, the other of the first and second valves is closed.

[0064] Furthermore, in device 110 of Figure 3, the circulation pump 122 is reversible. Device 110 allows, in particular, the reversible movement of liquid from the first compartment 118 to the second compartment 120 and from the second compartment 120 to the first compartment 118.

[0065] A preferred configuration of device 1 10, shown in Figure 3, will now be described.

[0066] The circulation pump 122 includes a first 188 and a second 190 access, connected respectively to the first 118 and the second 120 compartments.

[0067] The device 1 10 includes a first 191 and a second 192 upstream pipes and a first 193 and a second 194 downstream pipes.

[0068] The first upstream pipe 191 is arranged between the first collector 178 of the first compartment 118 and the first access 188 of the pump 122. The second upstream pipe 192 is arranged between the second collector 180 of the second compartment 120 and the second access 190 of the pump 122.

[0069] The first downstream pipe 193 is arranged between the second access 190 of the pump 122 and the second collector 180 of the second compartment 120. The second downstream pipe 194 is arranged between the first access 188 of the pump 122 and the first collector 178 of the first compartment 118.

[0070] Furthermore, device 110 includes a first 182 and a second 184 upstream valve and a first 183 and a second 185 downstream valve. The first upstream valve 182 is located on the first upstream pipe 191. The second upstream valve 184 is located on the second upstream pipe 192. The first downstream valve 183 is located on the first downstream pipe 193. The second downstream valve 185 is located on the second downstream pipe 194.

[0071] Preferably, device 1 10 is configured so that: when the first upstream valves 182 and downstream valves 183 are open, the second upstream valves 184 and downstream valves 185 are closed; and when the second upstream valves 184 and downstream valves 185 are open, the first upstream valves 182 and downstream valves 183 are closed.

[0072] Device 210 in Figure 4 will now be described more specifically.

[0073] In addition to the elements mentioned previously, the device 210 includes a fluid circuit 221 and a third 223 and a fourth 225 valve. Said third 223 and fourth 225 valves are three-way valves.

[0074] The fluid circuit 221 comprises a first 231, a second 233 and a third 235 branches, arranged in parallel between the third 223 and fourth 225 valves.

[0075] The circulation pump 22 and the first mixer 12 are arranged on the first branch 231 of the circuit. In the embodiment shown, the pump 22 is configured for fluid circulation from the third valve 223 to the fourth valve 225 in said first branch 231, said pump 22 being upstream of the first mixer 12.

[0076] The first 218 and the second 220 reserve compartments are located respectively on the second 233 and the third 235 branches of the circuit.

[0077] More specifically, in the device 210 of Figure 4, the first reserve compartment 218 has a first inlet 237 and a first outlet 239. This first outlet 239 corresponds to the second end 58 of the first fluid conduit 214 and is directed towards the third valve 223, as will be described below. The first inlet 237 is directed towards the fourth valve 225.

[0078] Similarly, in the device 210 of Figure 4, the second reserve compartment 220 has a second inlet 241 and a second outlet 243. This second inlet 241 corresponds to the second end 60 of the second fluid conduit 216 and is directed towards the fourth valve 225, as will be described below. The second outlet 243 is directed towards the third valve 223.

[0079] Process

[0080] A method for implementing the device 10, 110, 210 described above is detailed below. First, a mixture 42 of a first 44 and a second 46 immiscible liquid phases is introduced into the first reserve compartment 18, 118, 218.

[0081] Immiscible liquid phases include, for example, an oily phase and an aqueous phase. In one embodiment, the mixture 42 is already in the form of an emulsion, for example oil-in-water or water-in-oil, and comprises first droplets 48 of a second liquid phase 46 distributed within the first liquid phase 44.

[0082] Next, the pump 22, 122 is put into operation, so that a flow 26 of mixture circulates in the first conduit 14, 1 14, 214, between the first reserve compartment 18, 118, 218 and the first mixer 12.

[0083] The stream 26 then passes through the first mixer 12, inside which the first droplets 48 of the mixture are split into second droplets 49 of smaller size, as previously described.

[0084] The flow then circulates in the second conduit 16, 116, 216, between the first mixer 12 and the second reserve compartment 20, 120, 220.

[0085] Next, mixture 42 is transferred from the second compartment 20, 120, 220 to the first compartment 18, 1 18, 218.

[0086] In the case of device 10 in Figure 1, this transfer is carried out via the fluidic communication 62 between the first 18 and second 20 reserve compartments. The cases of device 110 in Figure 3 and device 210 in Figure 4 will be detailed below.

[0087] The circulation of mixture 42 through the first mixer 12 is then repeated in a similar manner through several successive cycles. With each pass through the first mixer 12, the droplets 48, 49 are broken down into smaller droplets.

[0088] A nanoemulsion of the second liquid phase 46 in the first liquid phase 44 is thus obtained. Preferably, the process leads to an emulsion in which the droplet diameter is less than 1 pm.

[0089] The 22, 122 continuous-drive pump allows for high flow rates while maintaining acceptable differential pressures for stretch mixers, preferably differential pressures below 100 bar. A suitable pump for such a device is, for example, the MRZ-1 1508 model, marketed by HNP Mikrosysteme GmbH.

[0090] In one embodiment, a droplet size dispersion measurement of the mixture 42 is performed after each pass through the mixer 12. Such a measurement is, for example, carried out using instruments that employ dynamic light scattering (DLS). This measurement allows for real-time adjustment of the process parameters. The implementation of the device 110 in Figure 3 will be described in more detail.

[0091] In a first step of said process, the first upstream valves 182 and downstream valves 183 are opened and the second upstream valves 184 and downstream valves 185 are closed; then the reversible pump 122 is put into operation in a first direction, from the first 118 to the second 120 compartment.

[0092] The first fluid conduit 114 is thus formed by: the first manifold 178; the first upstream pipe 191; the pump 122; and the first downstream pipe 193 up to the first mixer 12. The second fluid conduit 116 is formed by the first downstream pipe 193 from the first mixer 12 and by the second manifold 180.

[0093] Mixture 42 is thus transferred from the first 118 to the second 120 compartment, through the first mixer 12.

[0094] In a second stage of said process, the first upstream valves 182 and downstream valves 183 are closed and the second upstream valves 184 and downstream valves 185 are opened; then the reversible pump 122 is put into operation in a second direction, from the second 120 to the first 118 compartment.

[0095] The third fluid conduit 166 is thus formed by: the second manifold 180; the second upstream pipe 192; the pump 122; and the second downstream pipe 194, up to the second mixer 124. The fourth fluid conduit 168 is formed by the second downstream pipe 194 from the second mixer 124 and by the first manifold 178.

[0096] Mixture 42 is thus transferred from the second 120 to the first 118 compartment, through the second mixer 124.

[0097] The first and second steps described above are then repeated alternately, in the form of several successive cycles. The droplets of mixture 42 are thus fractionated alternately by the first 12 and by the second 124 mixers.

[0098] Device 110 allows for the isolation of fractions of mixture 42 at different stages of processing. Furthermore, at each transfer between the first 118 and second 120 compartments, the presence of valves 182, 183, 184, 185 prevents mixture 42 from passing through mixer 12, 124 located upstream of pump 122. Cavitation phenomena are thus avoided.

[0099] The method of implementing the device 210 of figure 4 will be described more specifically. In a first step of said method, the third 223 and the fourth 225 three-way valves are arranged in a first configuration, such that the third valve 223 isolates the third branch 235 of the circuit 221, and the fourth valve 225 isolates the second branch 233 of said circuit.

[0100] The first 214 and second 216 fluid conduits, described above, are thus formed. The first fluid conduit 214 passes successively through the first outlet 239 of the first compartment 218, the third valve 223 and the pump 22, to the first mixer 12. The second fluid conduit 216 passes successively through the first mixer 12, the fourth valve 225 and the second inlet 241 of the second compartment 220.

[0101] Next, the pump 22 is put into operation, so that the flow 26 of mixture circulates from the first outlet 239 of the first compartment 218, to the second inlet 241 of the second compartment 220, through the first mixer 12.

[0102] Mixture 42 is thus transferred from the first 218 to the second 220 compartment.

[0103] In a second step of said process, the third 223 and the fourth 225 three-way valves are arranged in a second configuration, such that the third valve 223 isolates the second branch 233 of the circuit 221, and the fourth valve 225 isolates the third branch 235 of said circuit.

[0104] Fifth 245 and sixth 247 fluid conduits are thus formed. The fifth fluid conduit 245 passes successively through the second outlet 243 of the second compartment 220, the third valve 223 and the pump 22, to the first mixer 12. The sixth fluid conduit 247 passes successively through the first mixer 12, the fourth valve 225 and the first inlet 237 of the first compartment 218.

[0105] Next, the pump 22 is put into operation, so that the flow 26 of mixture circulates in said fifth 245 and sixth 247 conduits, i.e. from the second outlet 243 of the second compartment 220 to the first inlet 237 of the first compartment 218, through the first mixer 12.

[0106] Mixture 42 is thus transferred from the second 220 to the first 218 compartment.

[0107] The first and second steps described above are then repeated alternately, in the form of several successive cycles. The droplets of mixture 42 are thus fractionated by the first mixer 12.

[0108] Like device 110 in Figure 3, device 210 in Figure 4 allows for the isolation of fractions of mixture 42 at different stages of processing. Device 210 is simpler than device 110 and, in particular, requires only one mixer 12. Nanoemulsion

[0109] The present invention also relates to a nanoemulsion that can be obtained by the process described above.

[0110] In other words, the nanoemulsion according to the invention has droplets with a size of less than 1 pm. By size, we mean the D50 in number.

[0111] Preferably, the size of the dispersed phase (i.e., the droplets) is less than 500 nm, preferably between 10 and 400 nm, preferably between 50 and 200 nm.

[0112] In the nanoemulsion according to the invention, the size distribution of the dispersed phase is narrow. This size distribution of the dispersed phase can be measured by the polydispersity index. A low polydispersity index is a major advantage for the delivery of active ingredient(s). It is measured using instruments that employ dynamic light scattering (DLS). According to the invention, it is less than 0.3.

[0113] The nanoemulsion according to the invention can be direct (i.e. oil-in-water or W / O or oily phase dispersed in continuous aqueous phase) or reverse (i.e. water-in-oil or W / O or aqueous phase dispersed in continuous oily phase).

[0114] The nanoemulsion according to the invention comprises an aqueous phase, an oily phase and at least one anionic or non-ionic surfactant.

[0115] The aqueous phase comprises water. Preferably, it also comprises at least one water-soluble organic solvent, preferably selected from polyols. Preferably, the water-soluble organic solvent is selected from glycerin (or glycerol) and maltodextrins. Preferably, water and optionally the water-soluble organic solvent are present in the nanoemulsion in an amount of between 5 and 75% by weight relative to the total weight of the nanoemulsion.

[0116] The oily phase can include any type of fat, solid or liquid at room temperature (20°C).

[0117] The oil phase typically comprises at least one vegetable oil and / or at least medium-chain triglycerides. Medium-chain triglycerides are defined as saturated triglycerides in which the three hydroxyl groups of glycerol are esterified by fatty acids containing 6 to 12 carbon atoms, preferably 8 to 10 carbon atoms. Medium-chain triglycerides are notably found in coconut oil and palm kernel oil.

[0118] The vegetable oil is preferably chosen from coconut oil, palm kernel oil, sweet almond oil, olive oil, apricot oil, linseed oil, sunflower oil, rapeseed oil, grapeseed oil, argan oil, sesame oil, avocado oil, jojoba oil, safflower seed oil, soybean oil, Karanja oil, tamanu oil and carrot oil.

[0119] The oily phase may also include a solid fat at room temperature (20°C), such as a wax.

[0120] Preferably, the oily phase is present in the nanoemulsion in an amount between 5 and 35% by weight relative to the total weight of nanoemulsion.

[0121] Preferably, the nanoemulsion according to the invention comprises at least one additional ingredient selected from oily perfume concentrates, pigment coloring materials, skincare actives (hydrophilic or lipophilic) and mixtures thereof.

[0122] The concentrated oil-based fragrance can be any fragrant substance or any mixture of fragrant substances. Generally, these fragrant substances are lipophilic.

[0123] Pigmentary coloring materials can be pigments, mother-of-pearls, and mixtures thereof.

[0124] The skincare actives, whether hydrophilic or lipophilic, can be chosen from among sunscreens (organic and mineral), cosmetic actives (e.g., anti-aging, anti-oily skin, moisturizing agents), and pharmaceutical actives (e.g., any compound meeting the definition of a pharmaceutically active ingredient or API). Preferably, the nanoemulsion includes at least one hydrophilic skincare active, preferably chosen from hyaluronic acid, plant extracts, collagen, peptides, and mixtures thereof.

[0125] Preferably, the additional ingredient is present in the nanoemulsion in an amount between 5 and 20% by weight relative to the total weight of nanoemulsion, preferably between 8 and 15% by weight.

[0126] The nanoemulsion also includes at least one anionic or nonionic surfactant. The anionic or nonionic surfactant is capable of forming vesicles.

[0127] Preferably, the nonionic surfactant comprises at least one glycerol or at least one glycerol-3-phosphate. Preferably, the nonionic surfactant is selected from phosphoglycerides and polyglycerol fatty acid esters. The phosphoglycerides may be hydrogenated or non-hydrogenated. Preferably, the phosphoglycerides are phosphatidylcholines (lecithins), hydrogenated or non-hydrogenated.

[0128] Polyglycerol fatty acid esters preferably comprise 2 to 12 glycerol units. The fatty acid may be saturated or unsaturated and preferably comprises 15 to 20 carbon atoms. Preferably, the fatty acid is selected from stearic acid, oleic acid, and ricinoleic acid. Preferably, the polyglycerol fatty acid ester is selected from polyglyceryl-10 stearate, polyglyceryl-4 oleate, polyglyceryl-10 oleate, polyglyceryl-3 ricinoleate, and mixtures thereof.

[0129] Preferably, the non-ionic surfactant is chosen from among phosphatidylcholines (lecithins), hydrogenated or non-hydrogenated, polyglyceryl-10 stearate, polyglyceryl-4 oleate, polyglyceryl-10 oleate, polyglyceryl-3 ricinoleate and mixtures thereof.

[0130] Preferably, the non-ionic surfactant is present in the nanoemulsion in an amount between 1 and 15% by weight relative to the total weight of nanoemulsion, preferably between 2 and 10% by weight.

[0131] The anionic surfactant is preferably chosen from among sulfate surfactants, isethionate surfactants, sulfoacetate surfactants and sarcosinate surfactants.

[0132] Preferably, the anionic surfactant is chosen from sodium coco sulfate (SCS), sodium cocoyl isethionate (SCI), sulfated castor oil, sodium lauryl sulfoacetate (SLSA), sodium lauroyl sarcosinate and mixtures thereof.

[0133] Preferably, the anionic surfactant is present in the nanoemulsion in an amount between 1 and 15% by weight relative to the total weight of nanoemulsion, preferably between 2 and 10% by weight.

[0134] The nanoemulsion may also include at least one preservative, for example phenoxyethanol.

[0135] The nanoemulsion may further comprise at least one divalent salt, preferably magnesium sulfate or calcium chloride. Preferably, the divalent salt is present in the nanoemulsion in an amount of between 0.1 and 5% by weight relative to the total weight of the nanoemulsion, preferably between 0.3 and 3% by weight.

[0136] The nanoemulsion according to the invention can be used as a perfume, but also as a sunscreen, makeup, skincare, hair care, baby hygiene, household cleaning, or textile care product. Example 1: Preparation of a composition according to the invention

[0137] The following formula is prepared, expressed by weight relative to the total weight of the composition:

[0138] Water: Qsp 100%

[0139] Glycerin: 15%

[0140] Medium-chain triglycerides (C8-C10) and / or vegetable oil comprising between 2% and 33% by weight of caprylic / capric triglycerides relative to the weight of caprylic / capric triglyceride oil: 3%

[0141] Hydrogenated lecithin: 3%

[0142] Concentrated fragrance on an oil base (Ocean SSA by TMI La Savonnerie): 15% Preservative: Qs

[0143] The formula is prepared using the following process:

[0144] The mixture is emulsified conventionally under rotor stator or mechanical agitation, then passed through the device according to the invention at 3400 rpm for 10 minutes.

[0145] Alternatively, the ingredients are introduced directly into the device according to the invention.

[0146] We obtain a droplet size between 80 and 150 nm, adjustable by the formulation.

[0147] The same formula is prepared using the following comparative method:

[0148] Emulsification is carried out conventionally under rotor-stator or mechanical agitation.

[0149] It is observed that the formula is not stable when prepared by the comparative method, whereas it is stable when prepared with the device according to the invention.

Claims

DEMANDS 1. Device (10, 110, 210) for preparing a nanoemulsion from a first (44) and a second (46) immiscible liquid phases, the device comprising a first stretch mixer (12) adapted to be traversed by a flow (26) of liquid; said first mixer comprising: an inlet zone (30); an outlet zone (32); and at least one microchannel (34), fluidly connecting the inlet and outlet zones; the inlet zone, the outlet zone and the at least one microchannel having respectively a first (36), a second (38) and a third (40) sections perpendicular to the flow, a ratio between the third section (40) and each of the first and second sections being less than or equal to 1 / 3; the device being characterized in that it further comprises: a first (14, 1 14, 214) and a second (16, 1 16, 216) fluid conduits; a first (18, 1 18, 218) and a second (20, 120, 220) reserve compartments;and a circulation pump (22, 122); a first end (54, 56) of the first and second fluid conduits opening respectively onto the inlet zone (30) and the outlet zone (32) of the first mixer; a second end (58, 60) of the first and second fluid conduits opening respectively onto the first (18, 118, 218) and the second (20, 120, 220) reserve compartments; the circulation pump being disposed on one of the first and second fluid conduits.

2. Preparation device according to claim 1, wherein the first mixer (12) further comprises a convergence zone (50) and a divergence zone (52), disposed between at least one microchannel and, respectively, the inlet zone and the outlet zone; the convergence zone having a decreasing cross-section in the direction of the flow, between the first and third sections; the divergence zone having an increasing cross-section in the direction of the flow, between the third and second sections.

3. Preparation device according to claim 1 or 2, wherein the first mixer (12) comprises a plurality of microchannels, fluidly connecting the inlet (30) and outlet (32) zones.

4. Preparation device according to any one of the preceding claims, wherein the circulation pump (22, 122) is disposed on the first fluid conduit (14, 114).

5. A preparation device (10) according to any one of the preceding claims, further comprising a fluidic communication (62) between the first (18) and second (20) reserve compartments, away from the first mixer.

6. A preparation device (110) according to any one of claims 1 to 4, further comprising: - a second stretch mixer (124), said second mixer comprising: an inlet zone (30); an outlet zone (32); and at least one microchannel (34), fluidly connecting the inlet and outlet zones; and - a third (166) and a fourth (168) fluid conduits; a first end of the third and fourth fluid conduits opening respectively onto the inlet area and the outlet area of ​​the second mixer; a second end of the third and fourth fluid conduits opening respectively onto the second (120) and the first (118) reserve compartments; the circulation pump (122) being disposed on one of the third and fourth fluid conduits, preferably on the third fluid conduit.

7. Preparation device according to claim 6, further comprising: at least one first valve (182, 183), disposed on one of the first and second fluid conduits; and at least one second valve (184, 185), disposed on one of the third and fourth fluid conduits; the device being configured so that when one of the first and second valves is open, the other of the first and second valves is closed.

8. A preparation device (210) according to any one of claims 1 to 4, further comprising: a fluid circuit (221); and a third (223) and a fourth (225) three-way valves; the fluid circuit (221) comprising a first (231), a second (233) and a third (235) branch, arranged in parallel between the third (223) and fourth (225) valves; the circulation pump (22) and the first stretch mixer (12) being arranged on the first branch (231) of the circuit; the first (218) and second (220) reserve compartments being arranged respectively on the second (233) and third (235) branches of the circuit; the first reserve compartment (218) comprising: a first outlet (239), corresponding to the second end (58) of the first fluid conduit (214) and directed towards the third valve (223); and a first inlet (237), directed towards the fourth valve (225); the second reserve compartment (220) comprising: a second inlet (241), corresponding to the second end (60) of the second fluid conduit (216) and directed towards the fourth valve (225); and a second outlet (243), directed towards the third valve (223); the device being configured such that, in a first configuration of the third (223) and fourth (225) valves, the first fluid conduit (214) extends between the first outlet (239) of the first compartment (218) and the first mixer (12); and the second fluid conduit (216) extends between the first mixer (12) and the second inlet (241) of the second compartment (220).

9. Preparation device according to claim 8, configured such that, in a second configuration of the third (223) and fourth (225) valves, a fifth fluid conduit (245) extends between the second outlet (243) of the second compartment (220) and the first mixer (12); and a sixth fluid conduit (247) extends between the first mixer (12) and the first inlet (237) of the first compartment (218).

10. A method for implementing a preparation device (10, 110, 210) according to any one of the preceding claims, the method comprising the following steps: - introduction, into the first reserve compartment (18, 118, 218), of a mixture of a first (44) and a second (46) immiscible liquid phases; then - implementation of several successive cycles, each cycle comprising the following steps: circulation of a flow (26) of mixture in the first conduit (14, 114, 214), between the first reserve compartment (18, 118, 218) and the first mixer (12); then circulation of said flow in the second conduit (16, 116, 216), between the first mixer (12) and the second reserve compartment (20, 120, 220); then transfer of the mixture from the second compartment (20, 120, 220) to the first reserve compartment (18, 118, 218); so as to obtain a nanoemulsion comprising droplets of second liquid phase suspended in the first liquid phase, a droplet diameter being preferably less than 1 pm.

11. A method according to claim 10 taken in combination with claim 6 or 7, wherein the step of transferring the mixture from the second compartment (120) to the first reserve compartment (118) comprises: a circulation of a flow of the mixture in the third conduit (166), between the second reserve compartment and the second mixer (124); then a circulation of said flow in the fourth conduit (168), between the second mixer and the first reserve compartment.

12. A method according to claim 10 taken in combination with claim 9, wherein the step of transferring the mixture from the second compartment (220) to the first reserve compartment (218) comprises: a circulation of a flow of the mixture in the fifth conduit (245), between the second compartment (220) and the first mixer (12); then a circulation of said flow in the sixth conduit (247), between the first mixer (12) and the first compartment (218).

13. Nanoemulsion obtainable by the process according to any one of claims 10 to 12.

14. Nanoemulsion according to claim 13, comprising an aqueous phase, an oily phase, and at least one anionic or non-ionic surfactant.

15. Nanoemulsion according to claim 14, wherein the aqueous phase comprises water and preferably further comprising at least one water-soluble organic solvent, preferably selected from polyols, selected from glycerin (or glycerol) and maltodextrins, and / or wherein the oily phase comprises at least one vegetable oil and / or at least medium-chain triglycerides, preferably the vegetable oil being selected from coconut oil, palm kernel oil, sweet almond oil, olive oil, apricot oil, linseed oil, sunflower oil, rapeseed oil, grapeseed oil, argan oil, sesame oil, avocado oil, jojoba oil, safflower seed oil, and soybean oil, and / or wherein the nonionic surfactant is selected from phosphoglycerides and polyglycerol fatty acid esters, preferably selected from phosphatidylcholines (lecithins), hydrogenated or non-hydrogenated,polyglyceryl-10 stearate, polyglyceryl-4 oleate, polyglyceryl-3 ricinoleate and mixtures thereof, and / or wherein the anionic surfactant is selected from sulfate surfactants, isethionate surfactants, sulfoacetate surfactants and sarcosinate surfactants, preferably from sodium coco sulfate, sodium cocoyl isethionate, sulfated castor oil, sodium lauryl sulfoacetate, sodium lauroyl sarcosinate and mixtures thereof.

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