APPRAISAL OF FASTNESS AND TENSILE PROPERTIES OF COTTON FABRIC DYED WITH NATURAL COLOURANTS BY PAD-STEAM METHOD
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Date
2015
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Publisher
College of Home Economics, University Of Peshawar.
Abstract
This study was conducted to appraise the fastness properties of some natural dyes
of plant origin on cotton fabric. Owing to the growing trend of going “green” throughout
the world, a renewed international interest has developed in the dyeing of textiles with
natural colourants. These dyes exhibit better biodegradability and are usually well
compatible with the environment. They contain natural colouring matter which is
generally non-allergic, non-toxic, non-carcinogenic and non-hazardous to the user and
environment. Common drawbacks of natural dyes are their non-uniform shades and poor
to moderate colourfastness. In this research project, solvent extracted dyes from alkanet
(Alkana tinctoria), cutch (Acacia catechu), madder (Rubia tinctorum) and ready to use
dyes from marigold flower (Tegetes erecta L) and Turkey red (Rubia cordifolia) have
been applied on cotton fabric through pad-steam dyeing procedure. To evaluate the
possibility of increasing their colour fastness, various dyeing auxiliaries (mordants, UV
absorbers, cationizing agents, crosslinkers, etc.) have been applied by pre-treatment and
post-treatment techniques. Metallic mordants included aluminium sulphate, copper
sulphate, ferric chloride, potassium dichromate and hydrated potassium aluminium
sulphate or alum.
Better fastness (wash, light, crocking), colour coordinates (lightness, chroma, hue
and colour strength) as well as improvement in tensile strength was achieved with postmordanting
of copper sulphate on most of these dyes. Pre-mordanting of potassium
dichromate brutally damaged the tensile strength of the alkanet dyed sample.
Cationization of cotton with quaternary ammonium compound (Albafix WFF) has
improved the fastness properties, tensile strength as well as relative colour strength (K/S)
of cotton dyed with alkanet, cutch and marigold flower dyes. Post-padding of reactive
UV absorber based on oxalanilide (UV-SUN) and UV absorber Rayosan C (heterocyclic
compound) greatly increased the light fastness of cotton fabric, dyed with these dyes.
Similarly, post-treatment of soft polyurethane emulsion (Dicrylan) has enhanced the light
and wash fastness as well as retained the tensile strength of natural dyed cotton. The use
of crosslinkers could not bring further enhancement in the K/S value of cotton dyed with
alkanet and generally, they yielded lighter shad