Failures and Improvements of Colour fastness to Rubbing/Crocking

Oeko-Tex Requirements:
rubbing requirement

Problem:

• Color fastness especially to wet rubbing, about 15 % failed.

Solution:

• Increase of final rinsing cycles.
• Dyestuffs of high color fastness
• Use dyestuffs that are recommended for the respective fiber material
• Optimize all processes according to actual technical know-how.
Color Fastness Rubbing/Crocking“Case Study”

Dyeing of a Cotton/Polyester Blend (60% / 40%)

1. Step: Dyeing of Polyester with Disperse Dye “BR1U Blue R”:

High Temperature Dyeing at 130 oC and Dyeing Bath pH Value = 5.5
Reductive Cleaning to remove excess Disperse Dye at 80 oC for at least
15 minutes in alkaline solution

2. Step: Dying of Cotton with Reactive Dye “Reactive Blue HEGN”:

Dyeing Bath free of alkaline before Reactive Dye into Dyeing Bath to
achieve a good” leveling” of Dyestuff all over the fabric.
After “leveling” is accomplished, the pH must be alkaline, to start the
chemical reaction, which fixes the dye to the cotton fiber.
Temperature 80 oC dyeing time at least one hour.

3. Step: After-treatment (“Soaping Process”, Washing)

Dyeing of a Cotton/Polyester Blend (60%/40%)
Reasons for bad Colorfastness:

• Polyester dyeing bath temperature not high enough, “Reductive cleaning” process insufficient

→ dyestuff not washed off the fabric, but only loosely fixed, bad colorfastness

• Alkaline pH of dyeing bath not adjusted to acidic value before the reactive dye is added, no leveling of dyestuff but local”heaps”, which are not fixed strongly to the fiber,

→ bad fastness

• Wrong bath temperature and dyeing process too short

→ bad colorfastness

• Insufficient soaping and rinsing after dyeing process finished

→bad colorfastness

why failure in rubbing

improve crocking test

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