What's the key to dyeing acrylic fiber?

The key to dyeing acrylic fiber lies in controlling the dye uptake rate and achieving uniform dye absorption. The following aspects can help guide this control.

1. Use of Retarder: An Indispensable "Brake"

Function: Retarders have a positive charge and compete with dye cations for dye sites on the fiber, effectively reducing the initial dye uptake rate and allowing time for uniform dye diffusion. Failure to use a retarder or using an inappropriate amount will inevitably result in smudging.

Handling: The optimal type and amount of retarder must be determined experimentally based on dye loading, color depth, and equipment conditions.

2. Heating: The Heart of the Process

Critical Temperature Zone (75°C to 95°C): This temperature range lies above the glass transition temperature (GTT) of acrylic fiber but below its boiling point. Fiber chains undergo vigorous motion, resulting in the fastest dye uptake. This is also the zone most prone to smudging.

Handling: A slow, computer-controlled heating rate (typically 0.5-1.5°C/minute) is essential. In this critical area, a gradual temperature increase can even be employed to ensure sufficient dye diffusion before further temperature increases.

3. PH Control: Critical for Stability

Range: Typically maintained in a slightly acidic environment pH 4.0 to 5.0, usually adjusted with acetic acid).

Reason: The appropriate pH stabilizes the dye bath, promotes the ionization of fiber acid groups, and ensures a stable dye shade. Excessively high or fluctuating pH values can affect dye uptake and levelness.

4. Dye Circulation: Power Guarantee

Requirement: The circulation pump must have sufficient head and flow to ensure robust dye penetration into all yarn layers and smooth forward and reverse circulation.

Inspection: Regularly inspect the pump and filter to prevent clogging that could lead to poor circulation.

If any question about dyeing solution,please contact us :info@tiankunchemical.com