Efficient Dyeing Process for Polyester Viscose Blended Fabrics

 

Optimized Dyeing Process for Polyester-Viscose Blended Fabrics

Introduction

Polyester-viscose blended fabrics combine the durability and wrinkle resistance of polyester with the softness and breathability of viscose, making them a popular choice for various textile applications. Achieving vibrant, uniform colors while maintaining fabric quality requires a precise and systematic dyeing process. This article outlines a professional dyeing procedure for a 50% polyester-viscose fabric (140 GSM, 5 kg batch) based on a specific industrial protocol, ensuring compliance with standards like Oekotex and optimal color fastness.

Process Overview

The dyeing process for polyester-viscose blends involves sequential steps to dye the polyester and viscose components separately, as they have different chemical affinities. Polyester is dyed using disperse dyes at high temperatures, while viscose is dyed with reactive dyes at lower temperatures. Additional steps like reduction clearing, neutralization, bleaching, soaping, and finishing ensure color consistency and fabric quality. The process described here uses a liquor ratio of 1:20 (100 liters) on Machine No. 5 for a 5 kg yellow fabric sample.

Step-by-Step Dyeing Process

1. Polyester Dyeing (135°C, 60 Minutes)

The polyester component is dyed first due to its hydrophobic nature, requiring high-temperature disperse dyeing.

Chemicals and Dosage:

Acetic Acid: 0.50 g/l (50 g) – Adjusts pH for optimal dye uptake.

Cross Color PLD: 0.60 g/l (60 g) – Dispersing agent to ensure even dye distribution.

Uniferol Buffer S: 1.0 g/l (100 g) – Maintains stable pH during dyeing.

Taicron Yellow EACT: 0.250% (12.5 g) – Disperse dye for yellow shade.

Procedure:

Load the fabric into the dyeing machine with 100 liters of water (1:20 liquor ratio).

Add chemicals and dye, then heat to 135°C.

Maintain temperature for 60 minutes to ensure dye penetration and fixation.

2. Reduction Clearing (90°C, 20 Minutes)

Reduction clearing removes unfixed disperse dyes from the polyester surface to prevent color bleeding.

Chemicals and Dosage:

Sodium Hydrosulphite: 2.0 g/l (200 g) – Reduces unfixed dyes.

Soda: 2.0 g/l (200 g) – Enhances cleaning efficiency.

Procedure:

Rinse thoroughly to remove residual chemicals.

Add chemicals and process for 20 minutes.

Cool the bath to 90°C.

3. Neutralization (60°C, 20 Minutes)

Neutralization stabilizes the fabric pH after reduction clearing.

Chemicals and Dosage:

Kleerix NAC Liq.: 1.0 g/l (100 g) – Neutralizing agent.

Procedure:

Cool the bath to 60°C.

Add Kleerix NAC Liq. and process for 20 minutes.

Rinse to prepare for viscose processing.

4. Viscose Bleaching (80°C, 30 Minutes)

Bleaching prepares the viscose component for dyeing by removing impurities and enhancing dye uptake.

Chemicals and Dosage:

Viscobleach: 3.0 g/l (300 g) – Bleaching agent for viscose fibers.

Procedure:

Heat the bath to 80°C.

Add Viscobleach and process for 30 minutes.

Follow with a hot rinse at 95°C for 10 minutes using Kappawet BOS (0.1 g/l, 4 g) as a wetting agent.

5. Neutralization (40°C, 15 Minutes)

Neutralization post-bleaching ensures the fabric is ready for reactive dyeing.

Chemicals and Dosage:

Kleerix NAC Liq.: 0.5 g/l (20 g) – Neutralizes residual bleach.

Terminox Ultra 50L: 0.15 g/l (60 g) – Stabilizes the bath.

Procedure:

Cool the bath to 40°C.

Add chemicals and process for 15 minutes.

Rinse thoroughly.

6. Viscose Dyeing (60°C, 60 Minutes)

Reactive dyes are used to color the viscose component, ensuring vibrant and wash-fast shades.

Chemicals and Dosage:

Dekol SNS: 0.75 g/l (30 g) – Leveling agent for even dyeing.

Ron Lube Plus C: 0.5 g/l (20 g) – Lubricant to reduce fiber friction.

Kappacom EIS: 0.5 g/l (20 g) – Dye bath stabilizer.

Sunfron Yellow SN2R: 0.50% (40 g) – Reactive dye for yellow shade.

Glauber’s Salt: 40 g/l (1600 g) – Promotes dye exhaustion.

Soda Ash: 10 g/l (400 g) – Fixes the dye to the viscose fibers.

Procedure:

Heat the bath to 60°C.

Add chemicals and dye, then process for 60 minutes.

Ensure proper dye fixation by maintaining temperature and pH.

7. Neutralization (50°C, 15 Minutes)

Neutralization removes excess alkali from the reactive dyeing process.

Chemicals and Dosage:

Kleerix NAC Liq. Green Acid: 0.75 g/l (30 g) – Neutralizing agent.

Procedure:

Cool the bath to 60°C.

Add Kleerix NAC Liq. Green Acid and process for 15 minutes.

Rinse to prepare for soaping.

8. Soaping (95/90°C, 20 Minutes)

Soaping removes unfixed reactive dyes to enhance color fastness.

Chemicals and Dosage:

Setawash SB: 1.0 g/l (40 g) – Soaping agent for reactive dyes.

Procedure:

Heat the bath to 95°C.

Add Setawash SB and process for 20 minutes.

Rinse thoroughly.

9. Fixing (40°C, 15 Minutes)

Fixing enhances the durability of the reactive dye on viscose.

Chemicals and Dosage:

Kappafix GG 100: 3.0 g/l (120 g) – Fixing agent.

Procedure:

Cool the bath to 40°C.

Add Kappafix GG 100 and process for 15 minutes.

Rinse to prepare for finishing.

10. Finishing by Padding

Padding applies a softener and neutralizing agent to improve fabric handle and stability.

Chemicals and Dosage:

Kleerix NAC Liq. Green Acid: 0.5 g/l (50 g) – Stabilizes pH.

Softsil Nano: 20 g/l (2000 g) – Softener for improved feel.

Procedure:

Prepare a padding solution with the chemicals.

Pass the fabric through the padding mangle to apply the solution evenly.

Dry the fabric to complete the process.

Key Considerations

Liquor Ratio: The 1:10 ratio ensures sufficient chemical and dye dispersion for uniform results.

Temperature Control: Precise temperature management (e.g., 135°C for polyester, 65°C for viscose) is critical for dye fixation and fabric integrity.

Chemical Dosage: Accurate dosing (in grams per liter or percentage) prevents overuse and ensures cost-efficiency.

Oekotex Compliance: All chemicals and processes must adhere to Oekotex standards for safe, sustainable textile production.

Machine Calibration: Machine No. 5 must be calibrated to handle the 5 kg load and 100-liter volume effectively.

Conclusion

The dyeing process for polyester-viscose blended fabrics requires a meticulous approach to achieve vibrant colors and maintain fabric quality. By following the outlined steps—polyester dyeing, reduction clearing, viscose bleaching, reactive dyeing, and finishing—textile manufacturers can produce high-quality, Oekotex-compliant fabrics. This process, tailored for a 140 GSM fabric with a yellow shade, demonstrates the balance of technical precision and chemical efficiency needed for successful dyeing.