Denim
garments are elegant fashionable textile products with very high level of
market all over the World. It has been well-known that unfinished denim
textiles are uncomfortable to wear due to their heavy and rigid structures,
therefore, it is necessary to achieve a soft handle, an enhanced comfort as
well as a desirable worn-out look by finishing. Great efforts have been hailed
to explore different chemical and physical finishing procedures for
discoloration and improving the handle of denim. They include
oxidizing-bleaching treatment, stonewashing, electrochemical reduction,
bio-washing, plasma treatment, laser irradiation and combination of
nanoparticles with enzymes. Oxidizing agents and stone washing with pumice were
first introduced in garment industry for aged-look denim finishing. However,
several negative impacts were observed on finished products and washing
machines by these two methods. To overcome their drawbacks, electrochemical
reduction technique has been later adopted to bleach denim fabrics by in-situ producing
reactive radical scavengers, but it has not yet been a simple scale-up
procedure. Enzymatic treatment of textiles has also been demonstrated as an
environmentally friendly method for textile finishing. In this regard, great
efforts have been devoted for denim finishing by pure laccase, mixture of
laccase/cellulase, pure acid cellulase, pure neutral cellulase, mixture of
amylase/cellulase/laccase, mixture of cellulase/methacrylate copolymer and
mixture of liquid ammonia/cellulase. It is worth mentioning that plasma and
laser etching methods are recently introduced as environmentally friendly
physical approaches to reduce the chemical agents and water consumption usage
in textile industry.
Several
research groups have found that stone-washing technique can be replaced by low
temperature plasmas of O2, air, argon and helium gases for removing
the oxidized indigo from denim surface. Laser has also been known as another
environmentally friendly approach for discoloration of denim in garment
industry. However, considerations should be undertaken to control laser
procedure parameters in order to avoid damaging in denim structure and preventing
reduction in the tensile strength. The advantages and disadvantages of
different methods are described in table below:
|
Methods |
Advantages |
Disadvantages |
|
Oxidizing-Bleaching
Treatment |
Strong
Discoloration power Simple
Application |
Relatively
high cost Possibility
to reduce mechanical properties Yellowing
effect Not
environmentally friendly Toxic
chemical usage Corrosion
of equipment Unpleasant
odor in working environment |
|
Stone Washing |
Desired vintage
effect Desired Softness Desired worn-out
look |
Corrosion of
equipment Time consumed stone
dust removing Possible to damage denim Not environment
friendly |
|
Electrochemical
Reduction |
Versatility
and high-energy efficiency Environmentally
friendly |
Not
available in scale-up Relatively
high cost |
|
Bio-washing |
Mild processing
conditions Environment friendly Low risk in denim
damage Recyclability of enzymes |
Necessity of enzyme
neutralization Chances of back
staining in enzyme treatment Inability to create
different designs |
|
Plasma
Treatment |
Environment
friendly Fast
discoloration No solid
waste and air pollution Dry
operation No negative
effect on bulk properties |
Necessity
to have operational skills Necessity
to optimize process parameters for effective discoloration Technical
challenges in scale-up Yellowing
effect |
|
Laser Irradiation |
Environment friendly Fast discoloration Dar operation Repeatability of
designs |
Necessity to control
laser parameters Necessity to have
operational skills Yellowing effect Possibility to
reduce the mechanical properties |
|
Combination
of Nana-particles with enzymes |
Additional
functionality on denim depending on nanoparticle type No negative
impact on mechanical properties |
Yellowing
effect |
