I. Temperature Control
1. Heating Rate: It is recommended to control the rate at 1℃/min to avoid uneven dyeing caused by excessive speed.
2. Holding Stage: For light colors, hold at 50-60℃ for 15-20 minutes; for dark colors, the holding time can be extended appropriately to ensure full dye penetration.
3. Cooling Rate: Allow to cool naturally to below 80℃ before washing to prevent creases caused by rapid cooling.
II. pH Management
1. Cotton Dyeing Stage: The pH value should be ≥11 to ensure sufficient fixation of reactive dyes.
2. Nylon Dyeing Stage: The pH value should be controlled between 5.5-6.0 to avoid uneven dyeing caused by excessively high (>6) or low (<5) pH values.
3. Neutralization Treatment: Neutralize with 2-3g/L detergent before dyeing nylon to ensure a uniform pH on the fabric surface. III. Feeding and Chemical Preparation
1. Chemical Preparation Method: Disperse dyes are first pulped with cold water, then dissolved in warm water (<50℃), stirred thoroughly, and then filtered before being added.
2. Feeding Sequence: Add acid (e.g., glacial acetic acid) first → auxiliary agent (leveling agent) → dye, avoiding direct contact with the fabric.
3. Feeding Speed: Dilute to 1:10 and inject slowly to avoid excessively high local concentrations.
IV. Equipment Operation
1. Liquor Ratio Adjustment: Ensure the fabric rotates one revolution in 1.5-2.0 minutes. Too high a speed can cause slippage, while too slow a speed results in uneven heating.
2. Fabric Speed Control: Adjust the nozzle diameter according to the fabric thickness to maintain a stable fabric speed and prevent knotting.
3. Regular Cleaning: Strengthen the cleaning of the dyeing vat and rinsing vat to prevent dye deposition.
V. Other Auxiliary Measures
1. Resistant Agent: A special resist agent can be used for cotton/nylon blended fabrics to reduce competitive dyeing.
2. Stabilizer: Add 0.5-1.5 g/L of dyeing stabilizer M-215 to reduce pH fluctuations.
3. Water quality management: Use soft water to avoid dye aggregation caused by calcium and magnesium ions.
