Cold Pad Batch Reactive Dyeing Control for Dense Woven Twills
Cold pad batch dyeing of dense twills requires low-volume trough turnover, dual-component alkali dosing, and precise rotation to eliminate tailing and core defects.
Hydrolysis Rate
Chemical Velocity
Speed at which a chemical compound reacts with water to break down into smaller components. Dyers monitor the hydrolysis rate of reactive dyes to ensure that the colorant bonds with the cellulose rather than reacting with the water in the bath. This reaction is irreversible and renders the dye incapable of forming a permanent bond with the fabric.
Alkaline Influence
Increasing the pH of the dye bath accelerates the reaction between the dye and the fiber but also increases the speed of the unwanted reaction with water. If the alkalinity is too high, a large portion of the dye is wasted, leading to poor color yield. Precise control of the soda ash addition is required to balance these two competing reactions.
Thermal Effect
Temperature plays a major role in the kinetic energy of the dye molecules and the frequency of their collisions with water. At higher temperatures, the breakdown of the dye occurs much faster, which reduces the effective dyeing time available for the process. A mill must calibrate the heating cycle to match the specific chemical properties of the dye being used.
Storage Condition
Concentrated dye solutions can begin to degrade if they are kept for too long before being added to the machine. The boundary of this stability is the time and the temperature of the storage tank, which must be kept cool to minimize the loss of reactivity. Monitoring the strength of the dye solution ensures that the final color of the fabric remains consistent across different production batches.
Stable chemical conditions are required for reproducible dyeing results.