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

January 10, 2017 | Contact Author | By: Rachel Grabenhofer
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Keywords: Shiseido | stability | o/w | emulsion | core-corona | phase | texture | sensation | agent | Pickering

Abstract: Emulsions are troublemakers. Surfactants can be used to keep their oil and water attitudes in check but they irritate some people. Pickering emulsions work, too, but are less effective and sticky wickets. Enter Shiseido's patented answer: corona-core microgels, which stabilize the situation and 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. 

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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.