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EP-4740930-A1 - STABLE OIL-IN-WATER MICROEMULSION

EP4740930A1EP 4740930 A1EP4740930 A1EP 4740930A1EP-4740930-A1

Abstract

The present invention relates to a composition in the form of an oil-in-water microemulsion having excellent stability over time. In particular, the composition according to the invention comprises a medium-chain fatty acid triglyceride, a low-HLB surfactant, a high-HLB surfactant, a diol selected from 1,3-propanediol and propylene glycol, and water. The invention also relates to the cosmetic use of said composition and a method for applying said composition to keratinous materials.

Inventors

  • POT, Monory
  • ACHILLE, Marie-Anne

Assignees

  • Dermosciences France

Dates

Publication Date
20260513
Application Date
20251103

Claims (15)

  1. Composition in the form of an oil-in-water microemulsion comprising at least: a) a medium-chain fatty acid triglyceride having 6 to 12 carbon atoms; b) a low HLB surfactant having an HLB ranging from 3 to 6; c) a high HLB surfactant having an HLB ranging from 13 to 20; d) a diol selected from 1,3-propanediol and propylene glycol; e) water, in which the mass ratio of the high HLB surfactant to the mixture (medium chain fatty acid triglyceride having 6 to 12 carbon atoms + low HLB surfactant) is greater than or equal to 0.85.
  2. Composition according to claim 1, wherein the low HLB surfactant has an HLB ranging from 5 to 6 and/or the high HLB surfactant has an HLB ranging from 14 to 18.
  3. Composition according to claim 1 or claim 2, wherein the mass ratio of the high HLB surfactant to the mixture (medium chain fatty acid triglyceride + low HLB surfactant) ranges from 0.90 to 5, preferably from 0.90 to 2.
  4. Composition according to any one of the preceding claims, wherein the mass ratio of medium-chain fatty acid triglycerides/low HLB surfactant is less than 1, preferably less than 0.8, preferably still less than 0.7, and more preferably between 0.40 and 0.65.
  5. Composition according to any one of the preceding claims, wherein the mass ratio of high HLB surfactant/low HLB surfactant is between 1.5 and 3, preferably between 1.5 and 2, more preferably between 1.6 and 1.8.
  6. Composition according to any one of the preceding claims, wherein the diol/triglyceride mass ratio of medium-chain fatty acids is greater than or equal to 0.6, preferably greater than or equal to 0.9, preferably still greater than or equal to 1, and preferably still between 1 and 2.
  7. Composition according to any one of the preceding claims, comprising from 3% to 20% by weight, preferably from 3% to 15% by weight, preferably still from 4% to 12% by weight, preferably still from 5% to 10% by weight of diol relative to the total weight of the composition.
  8. Composition according to any one of the preceding claims, wherein the diol is 1,3-propanediol.
  9. Composition according to any one of the preceding claims, wherein the medium-chain fatty acid triglyceride having 6 to 12 carbon atoms is caprylic/capric triglyceride.
  10. Composition according to any one of the preceding claims, wherein the low HLB surfactant comprises a monoglyceride and/or a diglyceride of medium-chain fatty acid selected from glyceryl monocaprate, glyceryl dicaprate, glyceryl monocaprylate, glyceryl dicaprylate, glyceryl caprate, glyceryl caprylate, glyceryl monocaprylate/caprate, glyceryl caprylate/caprate, glyceryl dicaprylate/caprate, preferably glyceryl caprylate.
  11. Composition according to any one of the preceding claims, wherein the high HLB surfactant comprises an ethoxylated sorbitan ester.
  12. Composition according to claim 11 wherein the high HLB surfactant is polysorbate 80.
  13. Composition according to any one of the preceding claims, comprising, in relation to the total weight of the composition: a) 7% to 9% by weight of triglyceride; b) 12% to 15% by weight of low HLB surfactant; c) 20% to 24% by weight of high HLB surfactant; d) 5% to 10% by weight of diol; and e) 42% to 56% water by weight.
  14. Composition according to any one of the preceding claims, further comprising at least one cosmetically and/or dermatologically acceptable agent and/or at least one biological active.
  15. Use of a composition according to any of the preceding claims as a makeup, hygiene, cleaning and/or care product for keratinous materials, preferably of the skin.

Description

technical field The present invention relates to a composition in the form of an oil-in-water microemulsion having excellent stability over time. In particular, the composition according to the invention comprises a medium-chain fatty acid triglyceride, a low-HLB surfactant, a high-HLB surfactant, a diol, and water. The invention also relates to the cosmetic use of said composition and a method for applying said composition to keratinous materials. Prior art Cosmetic and dermatological preparations for skin and hair care generally contain oil-soluble and water-soluble ingredients, often in the form of emulsions. An emulsion is a mixture of two or more immiscible or partially miscible liquids, where one liquid, called the dispersed or discontinuous phase, is dispersed in small droplets within the other, called the continuous phase. Emulsions are classified according to their continuous phase as oil-in-water (O/W) or water-in-oil (W/O) emulsions. Microemulsions represent a specific category of emulsions, obtained from four components: an aqueous phase, an oily phase, a surfactant, and a co-surfactant. The resulting composition leads to a microstructure made up of microdroplets smaller than 100 nanometers. This small droplet size allows light to pass through the microemulsion without being scattered, giving it a transparent appearance, unlike the opaque appearance of conventional emulsions. This property gives microemulsions significant advantages in cosmetic formulations. They offer better penetration of active ingredients thanks to the small droplet size, optical transparency due to the absence of light scattering, and the possibility of being prepared cold. This last characteristic reduces energy consumption during manufacturing and allows the use of heat-sensitive active ingredients that might degrade in a conventional emulsion. Another advantage of microemulsions lies in their ability to contain a larger quantity of active ingredients that are difficult to solubilize. Despite these advantages, the long-term stability of microemulsions remains a major technical challenge. Although generally considered thermodynamically stable, microemulsions can be subject to destabilizing phenomena during storage, such as sedimentation or coalescence. These processes can alter the physicochemical properties and efficacy of the cosmetic product over time. While increasing the surfactant concentration can improve the stability of microemulsions, high concentrations can result in a coarse, sticky, or greasy texture, thus altering the organoleptic properties of the product. A. Shah et al describes the formation of microemulsions from medium-chain triglycerides as a lipophilic phase and polysorbates as surfactants ( A. Shah et al, Drug Development and Industrial Pharmacy, 2017, vol. 44, pages 215-223 These microemulsions form only at very low lipophilic phase/surfactant ratios (1:9 or 2:8), thus requiring very high quantities of surfactants. The document also describes microemulsions prepared from a polysorbate, a medium-chain triglyceride, and a monoglyceride. By replicating the teachings in this document, the Applicant observed that these microemulsions tend to lose their stability over time. The document US2011/159104 describes microemulsions based on honey and bee products comprising triglycerides, low and high HLB surfactants, co-solvents and water. There is therefore a need to develop a composition in the form of a microemulsion, particularly for cosmetic and/or dermatological applications, which combines the advantages of microemulsions in terms of efficacy and organoleptic properties, while offering improved stability capable of withstanding long-term storage conditions. Summary of the invention According to a first aspect, the invention relates to a composition in the form of an oil-in-water microemulsion comprising at least: a) a medium-chain fatty acid triglyceride; b) a low HLB surfactant; c) a high HLB surfactant; d) a diol selected from 1,3-propanediol and propylene glycol; e) water. Advantageously, the low HLB surfactant has an HLB ranging from 3 to 6, preferably from 5 to 6 and/or the high HLB surfactant has an HLB ranging from 13 to 20, preferably from 14 to 18. Advantageously, the mass ratio of high HLB surfactant to mixture (medium chain fatty acid triglyceride + low HLB surfactant) is greater than or equal to 0.85, preferably from 0.90 to 5, preferably again from 0.90 to 2. According to one particular aspect, the invention relates to a composition in the form of an oil-in-water microemulsion comprising at least: a) a medium-chain fatty acid triglyceride having 6 to 12 carbon atoms; b) a low HLB surfactant having an HLB ranging from 3 to 6; c) a high HLB surfactant having an HLB ranging from 13 to 20; d) a diol selected from 1,3-propanediol and propylene glycol; e) water, in which the mass ratio of the high HLB surfactant to the mixture (medium chain fatty acid triglyceride having 6 to 12 carbon atoms + low