Study on the Usefulness of Far-infrared Radiating Minerals as Anti-Bacterial Containers for Cosmetics

This study aimed to investigate the utility of a mineral material that emits far-infrared rays as a method for continuous antibacterial action on the surfaces of cosmetic containers, in case of long-term use after opening. Methods: “MD-lite," a complex mineral that emits far-infrared rays, was added to plastic materials at a concentration of 2-5 w/v % to create pellets. These pellets were then extruded through a film forming machine and then spliced by 50 x 50 mm as film specimens. These specimens were tested for fungal resistance according to the standard method “ASTM G21-15 (2021)e1” and antibacterial activity according to “JIS Z 2801" by FITI Testing & Research Institute, a specialized organization. FT-IR equipment was also used to analyze the components of the films to confirm the presence of minerals. Ilite, a single mineral, served as a control. Results: As a result of testing the antibacterial properties of the film, it was confirmed that 5 types of mold and 4 types of pathogens were reduced by 3.9 to 5.7 log levels, indicating a sterilization rate of over 99.99%. These results are judged to be similar to the sterilization level of chemical disinfectants. In addition, the result of component analysis using FT-IR confirmed a unique detection pattern of “MD-lite” that was distinct from the control group, Ilite, and the same detection pattern was confirmed in the pellets and film containing this substance. Conclusion: Films impregnated with "MD-lite," a complex mineral that emits far-infrared rays, demonstrated excellent antibacterial properties, reaching levels close to the level of sterilization. Furthermore, FT-IR analysis confirmed the presence of the added ingredients. Therefore, applying this material to cosmetic containers, similar to the film composition, is expected to be highly beneficial for quality preservation by effectively eliminating microorganisms that can contaminate cosmetics after opening.