Patent Pick: Corona-core Microgels Go with Skin's Flow

As most formulators know, to successfully combine discontinuous phases, the addition of a surfactant emulsifier usually is required. Such emulsifying agents are especially useful in oil-in-water (o/w) emulsions, where finely dispersed liquid drops of the oil phase are surrounded by the emulsifying agent in the continuous water phase. This arrangement is said to provide superior texture and gives a dewy, fresh tactile sensation.

Some consumers, however, are sensitive to surfactants and want o/w emulsions without them. Such emulsions can be developed by adsorbing powder to the water/oil interface without using surfactant. These are known as Pickering emulsions.

According to Shiseido inventors, however, the preparation of o/w Pickering emulsions for personal care lotions and perfumery essences that remain stable in various environments has been difficult. This was the focus of newly developed corona-core microgels to prepare o/w emulsions, the particles of which recently were introduced at the IFSCC Congress. 

O/W emulsified compositions using corona-core microgel emulsifiers
U.S. Pat 9539554
Publication date: Jan. 10, 2017
Assignee: Shiseido Company, Ltd.

This patent relates to a corona-core microgel emulsifying agent composed of: a copolymer obtained by polymerizing polyethylene oxide macromonomers; hydrophobic monomers; and cross-linking monomers. It also relates to an o/w composition using this agent for emulsification.

According to the inventors, this system manifests superior emulsification stability and low skin irritation. It also is free of stickiness upon application, and manifests a dewy, fresh feel. Furthermore, it demonstrates superior fragrance durability.