Abstract:
Dyeing is a widely used operation in textile processing, and dyed textiles account for
significant amount of the total textile production. Colour, particularly colour consistency, is
a critical quality parameter in dyed textiles, on which is a high level of expectation is placed
by apparel manufacturer, as it can lead to the mismatching of garment panels and nonconformity
with customer requirements in readymade garments. Reactive dyes are popularly
applied to cotton knits due to the advantages of reactive dyes such as higher level of colour
fastness properties, obtaining different shades, and the applicability of various methods.
However, a lack of reproducibility in some cases has been observed in reactive dyeing on
cotton knits. Hence reproducibility has to be enhanced in order to obtain a cost effective,
competitive and environmental friendly reactive dyeing process. Therefore this research
focuses on the improvement of reproducibility of reactive dyeing on cotton knits.
I The reactive dyeing process depends on certain important factors such as the level of
pretreatment, quality of dyes, dyeing auxiliaries and water used, and the dye bath variables.
Therefore the bulk dyeing trials are performed on the level of pretreatment and the other
^ factors are kept constant. Thus the number of bulk dyeing trials including light, medium and
dark shades, are conducted on variables such as degree of whiteness, pH level and
absorbency of the material which are achieved during the pretreatment process. The
recommended degree of whiteness for this reproducibility was not exactly determined
because it ultimately affected to the strength of the white material. Therefore it can be
concluded that the degree of whiteness should be kept as high as possible without damaging
the fabric. The recommended pH level for the improvement of reproducibility was pH = 7.
At this pH level, maximum level of reproducibility can be achieved. The recommended
absorbency level for the improvement of reproducibility was 3 sec. according to the test
method of American Association of Textile Chemists and Colorists (AATCC) 79.By
maintaining the above parameters within the recommended range acceptable level of
reproducibility can be achieved in dyed cotton knits.
