Effects of Coexistent Components on the Antiperspirant Action of Aluminium Chlorohydrate

Abstract

Consumers are demanding a reliable antiperspirant product because they tend to sweat more as the number of hot days increases. In our previous studies, we devoted our efforts to effective utilization of aluminium chlorohydrate (ACH), a general-purpose antiperspirant active ingredient, in which we aimed to deposit a larger amount of ACH on the skin to improve the antiperspirant effect of an ACH-based product. In this study, we newly focus on various physical properties of an ACH gel because ACH works to occlude sweat glands by forming a gel when it reacts with sweat. We have finally developed a new technology to maintain the gel state in a wide range of pH, leading us to improve the antiperspirant efficiency. Evaluating the gelation behavior of ACH in an ACHsweat coexisting system, we found that the bicarbonate ion promoted and lactic acid obstructed the gelation. This implies that other inorganic acid ions and organic acid ions also affect the gelation of ACH. Therefore, we screened for various components to promote the gelation and found that sulfate ions showed the greatest influence on the gelation, inducing the highest antiperspirant efficiency. SAXS analysis of the ACH-sulfate ion coexisting gel demonstrated that sulfate strengthens the gel network comprising ACH nanoparticles. In conclusion, the formation of the stronger ACH gel assisted by sulfate ions greatly enhances the antiperspirant efficiency of the ACH-based product.