Process for the preparation of water-in-oil and oil-in-water nanoemulsions

A process for the preparation of a water-in-oil nanoemulsion wherein the dispersed phase is distributed in the dispersing phase in the form of droplets having a diameter ranging from 1 to 500 nm, said process comprising:

• preparing a homogeneous water/oil blend (I) having an interface tension lower than 1 mN/m and comprising water in an amount of 30 to 70% by weight and at least two surface-active agents having a different HLB, said surface-active agents being selected from the group consisting of non-ionic surface-active agents, anionic surface-active agents, and polymeric surface-active agents, and said surface-active agents being present in an amount of from 5 to 50% by weight;
• and
• diluting the blend (I) in a dispersing phase consisting of oil and a surface-active agent selected from the group consisting of a non-ionic surface-active agent, an anionic surface-active agent, and a polymeric surface- active agent, the quantity of the dispersing phase and the surface-active agent being sufficient to obtain a nanoemulsion having a HLB different from that of the blend (I).