Alkalinity Delivery
Automated chemical dispensing systems regulate the alkalinity of reactive dye baths to ensure optimal fixation on cellulose fibers. Controlled caustic soda dosing introduces liquid sodium hydroxide into the pad liquor at a measured rate. This adjustment raises the liquor pH to the specific level required for chemical bonding.
Without this action, the cellulose fibers cannot react with the dye molecules.
Hydrolysis Prevention
Separation of dye and alkali solutions until the moment of application minimizes the waste of raw materials through premature chemical reaction. If caustic soda dosing occurs too early in the storage tank, the dye reacts with water instead of the textile fibers. This hydrolyzed dye can no longer form covalent bonds with the cellulose, reducing color strength.
Immediate blending at the padder avoids this issue.
Fixation Kinetics
The chemical reaction rate between dye and cellulose depends directly on the concentration of hydroxyl ions in the bath. Real-time caustic soda dosing speeds up or slows down this reaction according to the process requirements.
Control System
Industrial finishing machines utilize electronic flow meters and feedback loops to maintain the target alkali concentration during continuous operations. During caustic soda dosing, a positive displacement pump adjusts the chemical flow rate based on fabric speed and liquor depletion. This dynamic control ensures that the fabric receives an identical amount of alkali from the beginning of the run to the end, preventing color variations.
Sensors monitor the effluent pH to ensure the system operates within safe environmental limits.
