November 1, 2023

Development of O/W mineral sunscreen with high UV protection ability using new zinc oxide suppressing zinc ion elution（We were selected as Top 10 finalist for the Applied Research Award at the 33rd Barcelona congress.）
At the IFSCC Congress 2023 held from September 4th to 7th, 2023, Tayca Co., Ltd. made a podium presentation aboutdevelopment of oil-in-water (O/W) mineral sunscreen with high UV protection ability that makes full use of formulation
technology and raw material design technology. The IFSCC Congress is the world’s largest international conference
held once every year, and is a cutting-edge conference where cosmetic engineers from around the world present theirlatest research. This year's conference was a great success, with 76 podium presentations and 373 poster presentations.
We made a podium presentation on the above theme and was selected as Top 10 finalist for the Applied ResearchAward at the 33rd Barcelona congress.
1. Presentation title
Oil-in-water mineral sunscreen with strong UV protection designed using formulation technology and raw material
development
2. Background
Recently, the demand for oil-in-water (O/W) sunscreens with high ultraviolet (UV) radiation protection has increased.
Similarly, the use of safe and low-environment-impact inorganic UV protection agents, such as titanium dioxide and zincoxide, has drawn much attention in recent years. However, the development of O/W mineral sunscreens with high UVprotection has been impeded by challenges in designing the formulations. Specifically, the instability of the formulations
owing to the elution of zinc ions from zinc oxide over time.
To overcome the challenge, we developed a new zinc oxide that suppresses the elution of zinc ions. Furthermore, using
this novel raw material, we designed an ideal O/W mineral sunscreen with high UV protection ability and high stability
over time.
3. Research content

Conventional base material

We found that the higher the hydrophobicity of the powder, thelower the number of zinc ions eluting and developed LE-ZnO(Low
Elution-ZnO)

withhighhydrophobicity.

Weselectedtriethoxycaprylylsilane(OTS) as surface treatment agent of LE-ZnO.

New base material

OTS bonds with the surface hydroxyl groups of zinc oxide throughhydrolysis and condensation. Therefore, to increase the reaction
points between them, we synthesized a zinc oxide base material toincrease the surface hydroxyl groups using our original particle

Fig. 1 Approach to increase hydrophobicity

synthesis technology. (Fig.1) As a results, we confirmed that LE-ZnO
using new zinc oxide base material, has higher hydrophobicity thanconventional ZnO, and the number of zinc ions elution is reduced.
Also, Formulation containing LE-ZnO had high stability over time
because it did not change after two months at 50 degrees and had
an in vivo SPF of 54, UVAPF of 21, having an extremely high UV

Fig. 2 External appearance of O/W formulation after 2 months at 50℃(Left)Formulation containing 15% of LE-ZnO(Right) Formulation containing 15% of Conventional ZnO

protection. The O/W mineral sunscreen we developed presents new possibilities for the cosmetic market /andcontributes significantly to reduce the burden on human skin.

Presenter profile

Isao Shimizu
TAYCA CORPORATIONOKAYAMA Research labolatory 4th section−Biography−
2015 Completed, Department of Applied Science, Graduate
School of Engineering, Hiroshima University
Joined TAYCA corporation and was assigned to the 4thsection of the Okayama Research labolatory.
Specializes in the development of base materials and surfacetreatments for inorganic UV scattering agents.
2 years from 2018 to 2020, he has been engaged insunscreen formulation development at our Tokyo Creation
Laboratory.