By: R. Nithyanandan and M. Subramanian Senthil Kannan

ABSTRACT

In conventional Method of dyeing of cotton with reactive dyes, alkali PH is should maintain in the dye bath. This method requires more electrolytes for exhaustion and alkali for fixation. In this paper the fibre modification technique based on polyacrylamide was discussed. When the fabric is treated with polyacrylamide, the primary hydroxyl groups of cellulose is (partially) modified into a amide groups, which intern leads the cellulose to act like as wool fibre and hence reactive dyes can be dyed on cotton at neutral PH in the absence of electrolyte and alkali.

INTRODUCTION

In current practice, cellulosic fibres are predominantly dyed with reactive dyes in the presence of a considerable amount of salt and fixed under alkaline conditions. However, dye fixation efficiency on cellulosic fibres is generally low (varying from 50 – 90%). This, results in a highly coloured dye effluent, which is unfavorable on environmental grounds. Furthermore, the high concentrations (40 – 100g/I) of electrolyte and alkali (5 – 20 g/I) required in cellulose fiber dyeing may pose additional effluent problems.

In this work, a new fiber –modification technique based on cationic acrylic copolymer. Pretreatment of cellulosic fiber with Polymer is believed to offer an opportunity for increasing both the substantivity and reactivity of fibers towards reactive dyes under neutral conditions. The nature of a reactive polymer resin is such that it may react with nucleophilic sites in cellulosic fibers or in the polymer itself, thus fixing the polymer to the substrate. During subsequent dyeing, further reactions between the polymer and the dyestuff, the fiber and the dyestuff, and the fibre and the polymer and can be expected to take place, forming crosslink within the fibers.

MATERIALS AND METHODS:

MATERIALS:

Plain fabric of count 32 of warp and weft is used throughout the process. The weight of the fabric is 123 GSM, its cover factor is 21.63, and Ends/inch is 98, Picks/ inch is 64.
Were Polyacrylamide resin, reactive dyes, Remazol Brill.Orange 3 R, Remazol Brill.Red 5B, Remazol Brill.Violet 5R, Remazol Turquiose Blue G, Procion Red M5B, Cibacron Green LS – 3 B, Cibacron Navy LS – G, Cibacron Red FN – R Cibacron Yellow FN – R are used.

METHODS:

The material is first Desized using enzyme, scoured with caustic soda and then bleached with hydrogen peroxide. The fabric neutralized and goes for dyeing.

DYEING

CONVENTIONAL METHOD:

The dye bath is set with calculated amount of dye solution and water using MLR 1:20. Enter the wetted well bleached fabric into the bath, raise the temperature to 40o c and work for 10 min then add the calculated quantity of salt in three portions at regular intervals (10 min). Raise the temperature to 50 o c and continue dyeing for 30 min, add the calculated quantity of soda ash and continue the dyeing for further 30 min. Finally take the material out, wash the material with cold water and then give soaping treatment to remove the unfixed dyestuffs and chemicals. The dyeing temperature and recipe of various reactive dyes are shown in table 1