Shade enhancer for Elastane in Polyamide/Elastane Blends
INTRODUCTION
Polyamide offers exceptional value and performance as the textile
fibre of choice. Polyamide has wide range of textile applications, such as
apparel, sportswear, swimwear, casual wear, fashion wear and hosiery. In the
market polyamide is preferred over polyester as:
· Fabrics can be dyed easily at atmospheric pressure in multiple
designs and colours
· Higher strength
· Softer touch
· Lighter weight and more elegant texture
Elastane/Lycra/Spandex is a modern synthetic fibre known for its
exceptional elasticity, hence its prevalence in athletic attire as well as in
apparel designed for comfort. The material is extremely comfortable,
lightweight and supple. It imparts stretchiness for underwear, lingerie,
sportswear and outerwear garments and in other stylish attire, such as
dancewear and club wear.
Relatively small percentages of elastane fibre is added to knit
fabrics of polyamide type to provide stretch and recovery to the fabrics and
the garments made from them. For fabrics that are knit on circular, or weft,
knitting machines the elastane is normally added as a bare yarn. Subsequent to knitting,
the fabric is preset, scoured, dyed, and then heat set.
There is a strong market trend towards the use of elastane
fibres. Polyamide in combination with elastane needs a lower heat-setting
temperature, which favours the retention of elastane properties. Combined with
elastane, polyamide offers good stretch-fit properties.
Different types of dye such as acid dyes and metal complex acid
dyes can be used for dyeing of polyamide fibres. Generally acid dyes which are
anionic do not dye elastane fibres properly under mild dyeing conditions, and
elastane fibres are slightly tinted. The wet fastness achieved on
Polyamide/elastane blends is usually lower than on 100% polyamide because the
dyes used for polyamide stain the elastane, and this stain subsequently washes
out during test. To overcome this problem, Sarex has developed
innovative product “Flexdye-ELA” which increases the affinity of acid dye
molecules towards elastane fibres thereby providing higher colour build up
especially black shades with good wet fastness on Polyamide/elastane blends.
Unique Features:
§ Solves the problem of “Grin through” of undyed
elastane fibre.
§ Develops solid shade in Polyamide/elastane
fabrics. No adverse effect on light and wet fastness.
§ Ensures stable and reproducible shades.
MATERIALS AND METHODS
Substrate: Polyamide/Lycra blended Ready for Dye garment
(innerwear)
EXPERIMENTAL
Step-1: Prior to dyeing
Treat Polyamide/Lycra blended Ready for Dye garment (innerwear) with
2% Flexdye-ELA + 1% Acetic Acid for pH 4.5 at 50°C for 20 min prior to dyeing.
Step-2: Dyeing
Dyeing is performed in the same bath of Step-1 by adding 4%
Levaset Black B (Black acid dye) + 1% Supergen-MX (Leveling agent) at 98°C for
30 min. Drain the bath followed by cold and warm rinse.
RESULTS AND DISCUSSION
Fabric — Dyed without Flexdye-ELA
% Colourant strength — 100
dE —
h — 262.776
L — 20.385
Fabric — Dyed with 2% Flexdye-ELA
% Colourant strength — 121
dE — 2.184
h — 262.776
L — 18.210
CONCLUSION
Flexdye-ELA treated fabric dyed with Black dye shows even dyeing
with an improvement in colourant strength and solid black shade while fabric
dyed without Flexdye-ELA shows grey shade.
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