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US-20260124123-A1 - STABLE OIL-IN-WATER MICROEMULSION

US20260124123A1US 20260124123 A1US20260124123 A1US 20260124123A1US-20260124123-A1

Abstract

The present invention relates to a composition in the form of an oil-in-water microemulsion with 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 chosen 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

  • Monory POT
  • Marie-Anne ACHILLE

Assignees

  • DERMOSCIENCES FRANCE

Dates

Publication Date
20260507
Application Date
20251105
Priority Date
20241106

Claims (15)

  1. 1 . 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 chosen from 1,3-propanediol and propylene glycol; e) water, wherein 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. 2 . The 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. 3 . The composition according to claim 1 , 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. 4 . The composition according to claim 1 , wherein the mass ratio of medium-chain fatty acid triglycerides/low HLB surfactant is less than 1, preferably less than 0.8, more preferably less than 0.7, and better between 0.40 and 0.65.
  5. 5 . The composition according to claim 1 , 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. 6 . The composition according to claim 1 , wherein the mass ratio of diol/medium-chain fatty acid triglyceride is greater than or equal to 0.6, preferably greater than or equal to 0.9, more preferably greater than or equal to 1, and more preferably between 1 and 2.
  7. 7 . The composition according to claim 1 , comprising from 3% to 20% by weight, preferably from 3% to 15% by weight, more preferably from 4% to 12% by weight, more preferably from 5% to 10% by weight of diol relative to the total weight of the composition.
  8. 8 . The composition according to claim 1 , wherein the diol is 1,3-propanediol.
  9. 9 . The composition according to claim 1 , wherein the medium-chain fatty acid triglyceride having 6 to 12 carbon atoms is caprylic/capric triglyceride.
  10. 10 . The composition according to claim 1 , wherein the low HLB surfactant comprises a monoglyceride and/or a diglyceride of medium-chain fatty acid chosen 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. 11 . The composition according to claim 1 , wherein the high HLB surfactant comprises an ethoxylated sorbitan ester.
  12. 12 . The composition according to claim 11 where the high HLB surfactant is polysorbate 80.
  13. 13 . The composition according to claim 1 , comprising, relative to the total weight of the composition: a) from 7% to 9% by weight of triglyceride; b) from 12% to 15% by weight of low HLB surfactant; c) from 20% to 24% by weight of high HLB surfactant; d) from 5% to 10% by weight of diol; and e) from 42% to 56% by weight of water.
  14. 14 . The composition according to claim 1 , further comprising at least one cosmetically and/or dermatologically acceptable agent and/or at least one biological active.
  15. 15 . A use of a composition according to claim 1 as a makeup, hygiene, cleaning, and/or care product for keratinous materials, preferably the skin.

Description

TECHNICAL FIELD The present invention relates to a composition in the form of a oil-in-water microemulsion with 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 intended for skin and appendage 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 phase or discontinuous phase, is dispersed in small droplets in the other, called the continuous phase. Emulsions are classified based on their continuous phase, into 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 formed of microdroplets with a size of less than 100 nanometers. This reduced 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 actives due to the small droplet size, optical transparency due to the absence of light scattering, and the possibility of being prepared cold. This latter characteristic reduces energy consumption during manufacturing and allows the use of thermosensitive actives that could be degraded in a conventional emulsion. Another advantage of microemulsions is their ability to contain a larger amount of difficult-to-solubilize actives. Despite these advantages, the long-term stability of microemulsions remains a major technical challenge. Although generally considered thermodynamically stable, microemulsions can be subject to destabilization phenomena during storage, such as sedimentation or coalescence. These processes can alter the physicochemical properties and effectiveness of the cosmetic product over time. While increasing the concentration of surfactant 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. Shah et al describes the formation of microemulsions from medium-chain triglycerides as the lipophilic phase and polysorbates as surfactants (A. Shah et al, Drug Development and Industrial Pharmacy, 2017, vol. 44, pages 215-223). These microemulsions only form at very low lipophilic phase/surfactant ratios (1:9 or 2:8), thus requiring very high amounts of surfactants. The document also describes microemulsions prepared from a polysorbate, a medium-chain triglyceride, and a monoglyceride. By reproducing the teaching of this document, the Applicant observed that these microemulsions tend to lose their stability over time. The document US2011/159104 describes honey-based microemulsions and apicultural products comprising triglycerides, low and high HLB surfactants, as well as 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 effectiveness 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 chosen 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 the mixture (medium-chain fatty acid triglyceride+low HLB surfactant) is greater than or equal to 0.85, preferably ranges from 0.90 to 5, more preferably from 0.90 to 2. According to a 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 chosen from 1,3-propanediol and propylene glycol;e) water,wherein the mass ratio of the high HLB surfactant to the mixture (medium-chain fatty acid triglyceride having 6 to 12 carbon atoms+low HL