In recent years, regulatory developments have limited the available types of biocides that can be used to protect polymers and textiles from bacterial and fungal growth. For example, the biocide OBPA was widely used to protect PVC and other plastics from such issues in the past, but the European Union blocked OBPA from sale in January 2013, prompting producers to seek other options. Commonly used alternatives such as DCOIT, BBIT, zinc pyrithione or IBPC have their own limitations, related to their use in various flexible polymer applications.
Outdoor applications in particular have seen an increase in performance requirements –– especially as regards antimicrobial effectiveness after exposure to water and ultraviolet light. Such additives also should not contribute to yellowing after UV exposure, but the available alternatives often fall short in this regard. And antimicrobial additives need to be able to meet the requirements for heat stability during the application process, while also avoiding initial discoloration and demonstrating compatibility with other additives in the formulation.