A novel O/W sunscreen formulation with enhanced UV protection when subjected to water
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Presented by: TOMOHIRO KANEKO
Introduction
As studies on damages induced by UV to the skin progressed, so have the awareness to wear sun protection products by not just women but men and children as well. Whilst a myriad of highly protective sun care products flourishes the market today, we must take into account that such products are practically used mainly in a water-rich environment such as the seaside and swimming pools. As highly water-repellent sunscreens are generally W/O formulations, their drawbacks at the summer leisure scene are their sticky and oily texture. Furthermore, it is generally known that when subjected to water, the UV protective performance of even the highly water-repellent formulations can deteriorate. We hereby report on the development of an O/W sunscreen formulation that is devoid of the sticky and oily texture of its W/O counterpart, whilst maintaining its water-repellency with further enhancement of UV protective performance when subjected to water.
Materials and Methods
O/W sunscreen formulations were prepared using various types of emulsifiers. O/W sunscreen formulations added with various polyoxyalkylene glyceryl ethers were also prepared in order to achieve a uniform coat when applied.
The formulation was applied onto a PMMA plate (Labshpere: HELIOPLATE HD6) to form a coat corresponding to 1.33mg/cm2 of material after which it was ambiently dried for 15 minutes. It was then subjected to an SPF analyzer (Labsphere: SPF Analyzer UV-2000S) to measure its in vitro SPF value. The PMMA plate was then submerged in a petri dish filled with tap water, and shook for 15 minutes using a shaker (AS ONE: Rocking mixer RM-80). The process was repeated again, after replacing with fresh tap water. The PMMA plate was dried for over 30 minutes after which it was subjected to the SPF analyzer to confirm the improvement of UV protective performance compared to prior to subjecting it to water.
Results
With samples prepared using nonionic surfactants and polyacrylic emulsifiers widely utilized for cosmetics, we could not obtain O/W sunscreen formulations with high water repellency. An O/W sunscreen formulation prepared using PEG-240/HDI Copolymer Bis-Decyltetradeceth-20 Ether, a polyurethane emulsifier, displayed high water repellency, but without improvement of UV protectability after subjecting it to water. Hence, in order to enhance the formation of a uniform coat after subjecting to water, we looked into the effects of adding various polyoxyalkylene glyceryl ethers and found that an O/W sunscreen formulated with PEG-240/HDI Copolymer Bis-Decyltetradeceth-20 Ether when combined with PEG/PPG/Polybutylene Glycol-8/5/3 Glycerin provided improved UV protective performance even after subjecting to water whilst providing an unprecedented refreshing texture with excellent usability.
Discussions
The known coat-forming ability of PEG-240/HDI Copolymer Bis-Decyltetradeceth-20 Ether is most likely enhancing the water-repellency of the O/W sunscreen. Furthermore, the combined usage of PEG/PPG/Polybutylene Glycol-8/5/3 Glycerin is believed to have contributed to the improvement in the uniformity of the coat after exposure to water. The combination of these two ingredients has enhanced not only the water-repellency of the formulation but the UV protective performance after its exposure to water as well.
Conclusions
Conventional technology was dependent on W/O type sunscreen formulations that had to sacrifice desired texture in order to impart water-repellency. The new combination of PEG-240/HDI Copolymer Bis-Decyltetradeceth-20 Ether and PEG/PPG/Polybutylene Glycol-8/5/3 Glycerin that we developed, retains the dewy refreshing texture characteristic of an O/W sunscreen formulation, whilst improving its water-repellency and further enhancing its UV protective performance when exposed to water. This provides excellent texture and UV protection simultaneously in water-rich environments such as swimming pools. It is also expected that sweating might further enhance UV protection. We proudly give birth to a revolutionary sunscreen formulation equipped with water-repellency, UV protection and excellent texture to maximize consumer satisfaction.
As studies on damages induced by UV to the skin progressed, so have the awareness to wear sun protection products by not just women but men and children as well. Whilst a myriad of highly protective sun care products flourishes the market today, we must take into account that such products are practically used mainly in a water-rich environment such as the seaside and swimming pools. As highly water-repellent sunscreens are generally W/O formulations, their drawbacks at the summer leisure scene are their sticky and oily texture. Furthermore, it is generally known that when subjected to water, the UV protective performance of even the highly water-repellent formulations can deteriorate. We hereby report on the development of an O/W sunscreen formulation that is devoid of the sticky and oily texture of its W/O counterpart, whilst maintaining its water-repellency with further enhancement of UV protective performance when subjected to water.
Materials and Methods
O/W sunscreen formulations were prepared using various types of emulsifiers. O/W sunscreen formulations added with various polyoxyalkylene glyceryl ethers were also prepared in order to achieve a uniform coat when applied.
The formulation was applied onto a PMMA plate (Labshpere: HELIOPLATE HD6) to form a coat corresponding to 1.33mg/cm2 of material after which it was ambiently dried for 15 minutes. It was then subjected to an SPF analyzer (Labsphere: SPF Analyzer UV-2000S) to measure its in vitro SPF value. The PMMA plate was then submerged in a petri dish filled with tap water, and shook for 15 minutes using a shaker (AS ONE: Rocking mixer RM-80). The process was repeated again, after replacing with fresh tap water. The PMMA plate was dried for over 30 minutes after which it was subjected to the SPF analyzer to confirm the improvement of UV protective performance compared to prior to subjecting it to water.
Results
With samples prepared using nonionic surfactants and polyacrylic emulsifiers widely utilized for cosmetics, we could not obtain O/W sunscreen formulations with high water repellency. An O/W sunscreen formulation prepared using PEG-240/HDI Copolymer Bis-Decyltetradeceth-20 Ether, a polyurethane emulsifier, displayed high water repellency, but without improvement of UV protectability after subjecting it to water. Hence, in order to enhance the formation of a uniform coat after subjecting to water, we looked into the effects of adding various polyoxyalkylene glyceryl ethers and found that an O/W sunscreen formulated with PEG-240/HDI Copolymer Bis-Decyltetradeceth-20 Ether when combined with PEG/PPG/Polybutylene Glycol-8/5/3 Glycerin provided improved UV protective performance even after subjecting to water whilst providing an unprecedented refreshing texture with excellent usability.
Discussions
The known coat-forming ability of PEG-240/HDI Copolymer Bis-Decyltetradeceth-20 Ether is most likely enhancing the water-repellency of the O/W sunscreen. Furthermore, the combined usage of PEG/PPG/Polybutylene Glycol-8/5/3 Glycerin is believed to have contributed to the improvement in the uniformity of the coat after exposure to water. The combination of these two ingredients has enhanced not only the water-repellency of the formulation but the UV protective performance after its exposure to water as well.
Conclusions
Conventional technology was dependent on W/O type sunscreen formulations that had to sacrifice desired texture in order to impart water-repellency. The new combination of PEG-240/HDI Copolymer Bis-Decyltetradeceth-20 Ether and PEG/PPG/Polybutylene Glycol-8/5/3 Glycerin that we developed, retains the dewy refreshing texture characteristic of an O/W sunscreen formulation, whilst improving its water-repellency and further enhancing its UV protective performance when exposed to water. This provides excellent texture and UV protection simultaneously in water-rich environments such as swimming pools. It is also expected that sweating might further enhance UV protection. We proudly give birth to a revolutionary sunscreen formulation equipped with water-repellency, UV protection and excellent texture to maximize consumer satisfaction.