How To Properly Dye Reactive Turquoise Blue Dyes

Dyeing reactive turquoise blue is one of the difficulties faced by dyeing factories (especially reactive turquoise blue KN-G, G133, etc.). Problems such as color spots, stains, and poor fastness are easily encountered during dyeing. This article will focus on its structural principles to explain how to avoid these dyeing problems.

Core Problems and Root Causes

The main problems can be summarized into the following three points, all of which are closely related to the structure of the dye itself:

Color Spots, Stains, and Mottling

Direct Causes: Insufficient dye dissolution and aggregation; rapid addition of electrolyte (sodium sulfate) leading to localized salting out; high water hardness.

Root Cause Analysis: Large molecular structure results in poor solubility and easy association; sensitivity to electrolytes, excessive amounts exacerbate aggregation.

Low Dyeing Rate and Poor Dyeing Depth

Direct Causes: Dyes do not easily penetrate fibers; low fixation rate.

Root Cause Analysis:Large molecular weight, poor diffusion; low fixation reaction efficiency.

Poor Wet Fastness

Direct Causes: Incomplete removal of unfixed dye (floating dye).

Root Cause Analysis:High dye directness; hydrolyzed dyes and unreacted dyes easily adhere to the fiber surface.

Key Control Points and Improvement Measures

To solve the above problems, meticulous control must be implemented in the following seven stages:

1. Pretreatment

Objective: To lay the foundation for uniform dyeing.

Key Measures: Ensure the fabric surface is white, the wicking effect is uniform, and the pH value is neutral. Soft water must be used to prevent calcium and magnesium ions from combining with the dye and causing stains.

2. Dye Dissolution

Objective: To achieve complete dissolution and prevent color spots.

Key Measures: The method of "cold water for pulping, hot water (below 60℃) for dilution" must be used. For dark colors, an appropriate amount of urea can be added to aid dissolution. After dissolution, the dye must be filtered before being added to the dyeing vat.

3. Electrolyte (Glauber's Salt) Control

Objective: To promote uniform dyeing and prevent salt precipitation.

Key Measures: Add in stages: Avoid adding all at once.

Sufficient dilution: Use clean water, not the dye vat backflow water, to dissolve the dye and prevent excessively high local concentrations.

Total Amount Control: Reactive turquoise blue is sensitive to sodium sulfate (Glauber's salt). Exceeding a certain concentration (e.g., 30 g/L) weakens its dyeing effect and increases the risk of salting out. For deep dyeing, consider a strategy of adding it in stages, starting with small amounts.

4. Alkali (Soda Ash) Control

Objective: To stabilize color and reduce hydrolysis.

Key Measures:

Gradual Addition: Follow the principle of "small amounts first, then larger amounts" (e.g., three additions in a 1:3:6 ratio), slowly increasing the pH value.

Avoid Pre-addition of Alkali: Especially when blending with colors like Reactive Yellow, pre-addition of alkali can easily lead to dye aggregation and precipitation.

5. Temperature and Time

Objective: To balance dyeing and hydrolysis.

Key Measures:

Appropriate High-Temperature Leveling: Leveling at 80℃ promotes macromolecular diffusion.

Cooling and Fixing: After leveling, cool to 60℃ before adding alkali for fixing to reduce dye hydrolysis.

Slow Heating:The heating rate after adding dye should be controlled at 1℃/min.

6. Water Quality Management

Objective: Eliminate interference from metal ions.

Key Measures: Use soft water throughout the process (hardness recommended below 50 mg/L, ideally below 15 mg/L). Chelating dispersants can be added to the dye bath, but care must be taken to ensure they do not strongly complex with dye metal ions (such as copper in copper phthalocyanine).

7. Soaping and Fixing

Objective: Remove floating dye and improve fastness.

Key Measures:

Thorough Soaping: Use a high-efficiency soaping agent and wash thoroughly at a neutral to slightly acidic pH (pH≈6) temperature of 90°C. Dark colors may require two washes.

Timely Fixing:Treat promptly after soaping with a dedicated fixing agent to effectively improve wet rubbing fastness.

**Process Optimization and Auxiliary Agent Selection Recommendations:**