Waterproof sunscreen with dramatically increased usability
The 25th IFSCC Congress 2008, Barcelona
Congress Award (Podium Presentation, Applied Research Award)
Development of a Water-Resistant/Detergent-Washable
Powder Coated with Stimuli-Responsive Polymer and Its Application to Sun-Care Products
What’s possible with the technology?
Waterproof sunscreen resistant to water and sweat can now be removed with regular soap, without any special cleansing product!
Waterproof sunscreen is essential for the beach and pool in summer. Many people use such products every day because of their sweat-resistant nature. In 2008, when this award was received, waterproof sunscreens required special cleansing products for removal because of their resistance to water. This research enabled the removal of waterproof sunscreen with the regular soap.
What’s the technology and why is it so great?
Coating powder was developed that resists neutral water and sweat but disperses in weak alkaline soap. The product is gentle to the skin and easy to remove!
Waterproof sunscreens must naturally resist water. Prior to this technology, the powder that protected the skin against ultraviolet light was coated with a water-insoluble substance. However, this made the sunscreen difficult to remove and required special cleansing products.
This award-winning technology developed a new coating powder that resists water but disperses in soap water. The secret to this development was pH―an index of hydrogen ion concentration. Low pH indicates acid, whereas high pH indicates alkali, and the middle of the two is neutral. Water and sweat are acidic to neutral, while soap water is a weak alkali. By focusing on this difference, we developed a special powder that resists acidic or neutral substance and only disperses in alkaline substance.
Nowadays, we take for granted that a product combines these two contradictory factors―water resistance and solubility in soap water― but at the time it was really novel. Therefore, high commendation was given to this technology, leading to the receipt of this award. This powder was applied to Shiseido ANESSA, as well as Shiseido Suncare, and has undergone further research that led to the use of even higher-function components at present.