Chlorine-based Agents and Elastomer Materials: Mechanism of Action, Degradation, and Application Development

Chlorine-based agents, such as sodium hypochlorite (NaOCl), have been used for over a century as highly reliable disinfectants in food manufacturing and medical settings. Not only does NaOCl meet many of the requirements for an ideal disinfectant, but it also possesses excellent cleaning properties. In NaOCl solutions, an equilibrium is maintained between two forms, undissociated hypochlorous acid (HOCl) and dissociated hypochlorite ion (OCl–), over the pH range of 4 to 10. While HOCl is a potent microbicidal species, OCl– is known for its powerful cleaning action. In recent years, therefore, the use of pH-controlled NaOCl solutions has been expanding in order to enhance the disinfecting and cleaning effects of NaOCl solutions. However, frequent use of pH-controlled NaOCl solutions often causes degradation or damage to elastomeric sealing materials, which can result in reduced sealing performance and physical contamination due to the delamination or fragmentation of the sealing materials. To maintain the stability and durability of sealing materials, it is necessary to understand the degradation mechanisms of sealing materials exposed to NaOCl solutions. This article focuses on hypochlorous acid and discusses the mechanisms of action of chlorine-based agents, the degradation mechanisms of elastomers, and potential applications.