The ultimate solution for an ideal non-chemical sunscreen
“A novel spherical zinc oxide renders unsurpassed transparency and texture”
365
Presented by: Kenji Kayahara
1. Introduction
The importance of UV protection has thoroughly penetrated amongst the consumers as is evident from the ever-expanding global sunscreen market of today. Whilst many of the currently distributed sunscreen products employ organic UV filters, there are concerns over such organic material on both human safety as well as marine pollution, calling for inorganic alternatives resulting recently in increasing demands for zinc oxide and titanium dioxide. On the other hand, non-chemical sunscreens containing only inorganic UV filters, are typically formulated with a combination of zinc oxide and titanium dioxide giving rise to issues such as lack of transparency and undesirable texture when applied to the skin, hence far from satisfactory to the consumers. In order to resolve such issues and to provide the consumers with an ideal non-chemical sunscreen, we developed a novel spherical zinc oxide that is readily dispersible allowing for the formation of a smooth and uniform coat when applied.
2. Materials and Methods
Zinc oxide offers UV protection through both scattering and absorption of UV rays, where the size of its primary particles as well as the uniformity of the emulsion in which it is contained, greatly affects its performance.
Using our novel and advanced particle synthesis technology, zinc oxide was spheroidized and its primary particle size was narrowly controlled to 40 nm to maximize transparency and the efficiency of UV scattering and absorption.
Furthermore, utilizing our original technology, its surface was finely treated with triethoxycaprylylsilane to give S-ZnO, developed to allow high dispersibility in any oils used in cosmetic products. S-ZnO is a safe surface-treated zinc oxide that complies with COMMISSION REGULATION (EU) 2016/621, effective as of 21 April 2016. W/O emulsions were evaluated via absorbance (UV-2000S, Labsphere, Inc.) and optical microscopy (VHX-1000, KEYENCE CORPORATION), whereas the coated film was evaluated by means of SEM (S-4800, Hitachi High-Tech Corporation), elemental analysis (EMAX ENERGY EX-220, HORIBA, Ltd.) and Haze (NDH2000, NIPPON DENSHOKU INDUSTRIES Co.,Ltd.).
3. Results
The absorbance of W/O emulsions, one formulated with S-ZnO and another with C-ZnO (conventional zinc oxide surface-treated with triethoxycaprylylsilane), were measured and compared. S-ZnO exhibited high absorbance across the entire UV spectrum, and at its maximum, exceeded that of C-ZnO by as much as 58 %, confirming its superior capability for UV protection. S-ZnO is highly dispersible in oils, where even under mild shear conditions e.g. using a propeller blade, a uniform fine dispersion was readily available. Its spherical nature and lesser aggregation also resulted in improvement of texture. Furthermore, the coat formed on applying S-ZnO was found to be 6 times more transparent than that of C-ZnO by Haze measurement, showing a drastic improvement in transparency.
4. Discussion and Conclusions
S-ZnO, developed via advanced particle design and surface treatment technologies, provides easy dispersibility and smoothness to the applied coat, thereby optimizing the transparency and UV protecting capabilities that are the potentials of zinc oxide. Other than just a mere functional improvement of S-ZnO itself, the fact that more than 20 % of the total inorganic material required to fulfill the sunscreen specifications can now be reduced, significantly improves the transparency and texture to the extent that is more or less comparable to sunscreens formulated with organic material. Further to note is the ease with which S-ZnO can be dispersed allowing within the sunscreen manufacturing process, a shorter time for dispersion as well as drastic energy saving during dispersion. The smoothness of the applied coat gives a high transparency as never before, providing natural finish for skin of any tones. This study not only resolves the long-pending issues related to the unsatisfactory transparency and texture of conventional non-chemical sunscreens but also contributes to SDGs in many ways.
The importance of UV protection has thoroughly penetrated amongst the consumers as is evident from the ever-expanding global sunscreen market of today. Whilst many of the currently distributed sunscreen products employ organic UV filters, there are concerns over such organic material on both human safety as well as marine pollution, calling for inorganic alternatives resulting recently in increasing demands for zinc oxide and titanium dioxide. On the other hand, non-chemical sunscreens containing only inorganic UV filters, are typically formulated with a combination of zinc oxide and titanium dioxide giving rise to issues such as lack of transparency and undesirable texture when applied to the skin, hence far from satisfactory to the consumers. In order to resolve such issues and to provide the consumers with an ideal non-chemical sunscreen, we developed a novel spherical zinc oxide that is readily dispersible allowing for the formation of a smooth and uniform coat when applied.
2. Materials and Methods
Zinc oxide offers UV protection through both scattering and absorption of UV rays, where the size of its primary particles as well as the uniformity of the emulsion in which it is contained, greatly affects its performance.
Using our novel and advanced particle synthesis technology, zinc oxide was spheroidized and its primary particle size was narrowly controlled to 40 nm to maximize transparency and the efficiency of UV scattering and absorption.
Furthermore, utilizing our original technology, its surface was finely treated with triethoxycaprylylsilane to give S-ZnO, developed to allow high dispersibility in any oils used in cosmetic products. S-ZnO is a safe surface-treated zinc oxide that complies with COMMISSION REGULATION (EU) 2016/621, effective as of 21 April 2016. W/O emulsions were evaluated via absorbance (UV-2000S, Labsphere, Inc.) and optical microscopy (VHX-1000, KEYENCE CORPORATION), whereas the coated film was evaluated by means of SEM (S-4800, Hitachi High-Tech Corporation), elemental analysis (EMAX ENERGY EX-220, HORIBA, Ltd.) and Haze (NDH2000, NIPPON DENSHOKU INDUSTRIES Co.,Ltd.).
3. Results
The absorbance of W/O emulsions, one formulated with S-ZnO and another with C-ZnO (conventional zinc oxide surface-treated with triethoxycaprylylsilane), were measured and compared. S-ZnO exhibited high absorbance across the entire UV spectrum, and at its maximum, exceeded that of C-ZnO by as much as 58 %, confirming its superior capability for UV protection. S-ZnO is highly dispersible in oils, where even under mild shear conditions e.g. using a propeller blade, a uniform fine dispersion was readily available. Its spherical nature and lesser aggregation also resulted in improvement of texture. Furthermore, the coat formed on applying S-ZnO was found to be 6 times more transparent than that of C-ZnO by Haze measurement, showing a drastic improvement in transparency.
4. Discussion and Conclusions
S-ZnO, developed via advanced particle design and surface treatment technologies, provides easy dispersibility and smoothness to the applied coat, thereby optimizing the transparency and UV protecting capabilities that are the potentials of zinc oxide. Other than just a mere functional improvement of S-ZnO itself, the fact that more than 20 % of the total inorganic material required to fulfill the sunscreen specifications can now be reduced, significantly improves the transparency and texture to the extent that is more or less comparable to sunscreens formulated with organic material. Further to note is the ease with which S-ZnO can be dispersed allowing within the sunscreen manufacturing process, a shorter time for dispersion as well as drastic energy saving during dispersion. The smoothness of the applied coat gives a high transparency as never before, providing natural finish for skin of any tones. This study not only resolves the long-pending issues related to the unsatisfactory transparency and texture of conventional non-chemical sunscreens but also contributes to SDGs in many ways.