Principle of Cationic Dyeing Process

With the increase of temperature, when the temperature reaches the glass transition temperature of acrylic fiber, the generation and intensification of molecular chain movement increase the micro gaps between molecular chains. At this time, the dye diffuses into the interior of the fiber. Due to the tight structure of acrylic fiber and the strong electrical attraction between the dye and the fiber, the diffusion resistance of the dye inside the fiber is relatively high. Therefore, some people believe that the dye diffuses one dye seat at a time. In short, the diffusion of cationic dyes in acrylic fibers requires high energy, so transfer dyeing is relatively difficult. Temperature has a significant

The basic principle of cationic staining

The process of salt formation and binding between colored cations of cationic dyes and negatively charged functional groups on fibers, namely:

Fiber COOH+CL dye → Fiber COO dye+HCL

This binding process belongs to the localization adsorption process, and the dyeing of acrylic fiber by cationic dyes involves three processes.

1. Adsorption - Acrylic fibers in water are negatively charged due to the dissociation of acidic groups, which easily adsorbs dye cations and neutralizes the negative charge on the fiber surface. As dye ions continue to diffuse into the fiber, the surface charge of the fiber increases, and the fiber re adsorbs the dye.

2. Diffusion - The diffusion of dyes into fibers is a complex process. The diffusion of dye molecules is usually difficult and often requires an increase in temperature.

3. Fixation - Dye fixation is the process of salt formation between dye cations and anionic groups on fibers, which is essentially an irreversible reaction.

Dyeing characteristics of cationic staining

When cationic dyes are used to dye acrylic fibers, the adsorption is fast and can easily cause uneven adsorption, and excessive heating can lead to uneven dyeing. Once the dyeing is uneven, it is difficult to achieve even dyeing through transfer dyeing. For this reason, the following factors must be taken into account:

1. Adjustment of pH value: In order to achieve uniform dyeing, it is generally most appropriate to control the pH value between 4-5 when dyeing with cationic dyes.

2. Temperature control: Gradually increase the temperature in sections. Generally, the temperature can be raised faster below 60 degrees, and slower above 60 degrees. After 100 degrees, it is necessary to keep it warm for 30-50 minutes to ensure good penetration, otherwise it will affect the color fastness.

3. Application of dyeing buffer: In order to achieve uniform dyeing effect, dyeing buffer can be added to the dyeing bath. The dyeing buffer itself is a colorless cationic dye, which can also be used to dye acrylic fibers during cationic dyeing.

4. Electrolyte: Electrolytes can have a slow dyeing effect on cationic dyes when dyeing acrylic fibers.

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