Summary
To determine the most suitable padding method for dyeing oncellulose fabric for a particular group of reactive dyes, two vinyl sulphonereactive dyes containing sulphato ethyl sulphone i.e. Remazol G/Y RNL andRemazol Black B and two monochlorotriazine i.e. Cibacron G/Y P2RN and CibacronGrey PTGE were applied under two different dyeing methods- Semi Continuous (PadBatch) and Continuous (Pad Thermofix) method, evaluated the yield by latestversion of spectrophotometer (Datacolor SF 650+). It was observed that lowsubstantive dyes show good yield in semi continuous while high substantive dyesgive better yield in Pad thermofix. Both methods have good fastness results.
Introduction
It always is a fascinating to improve the yield and qualityof the dyes by introducing new class, modified groups and even the dyeingmethod. Reactive dyes differ from other class of dyes in term of that themolecule of a reactive dyes contains one or more reactive groups capable offorming a covalent bond with a compatible fibre group. The main step in thedyeing procedure with a dye of such type comprise adsorption on the fibre,diffusion into the fibre and react with the specific group of fibre[1], bymeans of nucleophilic addition or nucleophilic substitution. Reactive dyescontaining sulphatoethylsulphone give addition reaction, while the dyescontaining Cyanuric chloride give substitution reaction in presence of alkali[2].
Reactive dyes have been very popular due to their high wetfastness, brilliance and range of hues. Continuous dyeing with reactive dyes isnow important due to its high productivity and consistency of shades over runs[3].Continuous Dyeing with reactive dyes, usually done by padding process i.e.Pad thermofix, pad batch and pad steam. In this study the only pad thermofixand pad batch are being discussed. In pad batch process, more dwell time by meansof batching is provided to fix the dye into the fibre. In fact it is an exhaustmethod at extremely low liquor ratio and ambient temperature [4]. Theimpregnated batch is store separately from padding machine and thus allow widevariation of dwell time according to the dye selected and the pH of theimpregnated temperature. Whereas in Pad thermofix method dye is fixed into thefibre by means of high temperature, which shorten the dwell time [4]. Due tovariation in yield and fastness properties and feasibility during dyeing,different reactive groups give different yield in different process on thebasis of their substantivity and reactivity. In this present work we sought toreview the suitable dyeing process for certain reactive group in short liquor.
About the Authors:
The authorsare associated with Applied Chemistry Research Centre (Textile Section), PCSIRLaboratories Complex, Off University Road, Karachi, Pakistan.
Comments