THE DYEING OF LYOCELL FABRIC WITH DIRECT DYES

Presented By: Muhammad ZeeshanRegistration #: 14-NTU-0122

Introduction

Lyocell is a form of rayon which consists of regenerated cellulose fibre made from dissolving pulp.

Direct dyes are dyes with substantivity for cellulosic fibres, normally applied from an aqueous dyebath containing an electrolyte, either sodium chloride.

Aim of Study

dye-ability of Lyocell with direct dyes.

Comparison of dyeing behaviour of the fibre to:

Cotton regular viscose.

Materials

Six samples of each scoured and bleached woven

Lyocell(2g) Cotton(2g) Viscose(2g)

Dyes Direct Red Direct Blue Direct Yellow

Electrolyte Sodium Chloride(15-25g/l)

Procedure

Dip fabric into cold water Dyeing will take place in laboratory scale

dyeing machine using liquor ratio 1:30 Samples (2.00 g) of each of the three types

of fibre were dyed separately by using 1, 2 and 4%(owf) dye.

Electrolyte is added to increase dye exhaustion(20% at 40°C and 80% at 90°C)

Dyed sample was removed, washed with cold water and allowed to dry in the open air.

Tests

Colour measurement: The reflectance values of the undyed samples of Lyocell, cotton and viscose, as well as those of each of the dry dyeings on Lyocell, cotton and viscose, were measured using a Macbeth MS2020 spectrophotometer. Wash fastness: ISOC06/C2 wash test was determined using the standard method.

Results

Lyocell dyeings were duller Blue slightly redder Redder slightly yellower Yellow slightly redder

than respective dyeings on cotton and viscose. Colour strengths of the dyeings on Lyocell

were lower than those on cotton and viscose.

Dyeings on the pairs of different types of fibre increased with increasing concentration of dye applied.

Conclusion

The colour strength of the dyeings on Lyocell was lower than on cotton and viscose.

The wash fastness of dyeings on Lyocell was comparable to that of dyeings on cotton and viscose.

Dyeability of Lyocell with the three direct dyes more closely resembles that of cotton than regular viscose.