The principle of bleaching fabrics is mainly achieved through oxidation or reduction. Bleach is a process that uses the oxidation or reduction action of chemicals to remove oxidizable or reducible dirt from fabrics that was not completely removed during the main washing process. Specifically, bleaching can be divided into two types: Oxidative bleaching and reductive bleaching.
Oxidative bleaching
Oxidative bleaching is a process in which oxidants (such as sodium hypochlorite, calcium hypochlorite, etc.) react with the pigments in the fabric, disrupting the chromophores in the pigments, causing them to fade and dissolve in water. Common oxidative bleaching agents include sodium hypochlorite and calcium hypochlorite. Sodium hypochlorite has a better bleaching effect under ph values of 9 to 11, with temperature controlled within 60 ℃ and time controlled within 6 to 9 minutes.
Reduction bleach
Reduction bleaching is the process of reducing pigments to chromophore compounds using reducing agents such as sodium bisulfite, but this effect is unstable and prone to discoloration due to oxidation. Reduction bleaching is relatively rare in industrial applications.
