What is Biopolishing?
Biopolishing is a finishing process carried out before,
during, or after dyeing, which increases fabric superiority
by reducing hairiness and pilling of cellulosic fabrics
leading to velvety, slicker feel, and brighter color (Ibrahim
et al., 2011). The purpose of the process is to eliminate
protruding micro hairs of cotton by an interaction of
cellulase (Cavaco-Paulo, 1998; Cavaco-Paulo and
Almeida, 1996; Lenting and Warmoeskerken, 2001;
Stewart, 2005).
The main advantage of this process is the prevention of pilling,
which leads to an unattractive, knotty fabric appearance, thus
affecting garment quality. Cellulases hydrolyze the microfibrils
(fuzz) protruding from the surface of yarn because they are most
susceptible to enzymatic attack. This weakens the microfibrils,
which tend to break off from the main body of the fiber and
leave a smoother yarn surface. After treatment, the fabric shows
lower pilling tendency. Unlike conventional softeners, which
tend to be washed out and often result in a greasy feel, the
softness-enhancing effects of cellulases are wash proof and
nongreasy
Objects of Biopolishing in Textile:
➢ To removes protruding fibers and slubs
➢ To removes Hairiness, fluffs and pills.
➢ To Prevented material sticking.
➢ To softens fabric hand and improved handle.
➢ To achievement of surface smoothness and a clear structural
appearance and improved lustre .
➢ To improved material texture relaxation and increased
flexibility.
➢ To improved sew-ability, low pilling tendency and fast to
washing.
➢ To converted fabrics from poor quality, uneven, napped,
knoppy material surface to lustrous, soft, elegant, top quality
with a fine, high quality surface appearance.
Biopolishing Process in Textile:
There are two process of Bio-polishing
.
A. Dyeing followed by bio-polishing.
B. Bio-polishing before Dyeing.
Application Method:
Enzymatic cellulose degradation is also possible during reactive
dyeing. Here the dyeing process as well as bio-polishing will be
affected. By applying this process, number of washes, time, cost
and energy can be saved by this one bath method. However, it
should be noted that there is some reduction in colour yield of
reactive dyeing. This is because reactive dyeing is carried out in
acidic pH during bio-polishing. But precaution is taken during
addition of soda-ash as reactive dyes require alkaline condition for
its fixation. The fabric is made neutral before adding soda-ash. It is
found that neutral stable enzymes are more suitable in this type of
one bath treatment.
A. Process sequence of Dyeing followed by
Biopolishing:
Scoured & bleaching sample
↓
Dye addition
↓
Salt addition
↓
Soda ash addition
↓
Dyeing
↓
Hot wash
↓
Hot wash
↓
Soaping (at boil temperature )
↓
Hot Wash
↓
Cold wash
↓
Biopolishing
↓
Cold wash
↓
Drying
B. Process sequence of Biopolishing before
Dyeing:
Scoured & bleaching sample
↓
Bio-polishing
↓
Cold wash
↓
Drying
↓
Dye addition
↓
Salt addition
↓
Soda ash addition
↓
Hot wash
↓
Hot wash
↓
Soaping (at boil temperature )
↓
Hot Wash
↓
Cold wash
↓
Drying
Process Variables:
To achieve optimum bio-polishing, the process variables
have been varied as mentioned below:
Concentration: Concentration of enzyme: 0.5%, 1%,
2%, 2.5%, 3% & 4%.
Temperature: Temperatures are 400C, 450C, 500C, 550C
& 600C.
pH: 3 – 4, 4 – 5 & 5 – 6.
Liquor ratio (M : L): 1:5, 1:10, 1:15 & 1:20.
Mechanical Agitation: Vigorous Stirring, Medium
Stirring & Without Stirring.
Standard Recipe for Biopolishing:
• Concentration of Enzyme = 3%
• M : L = 1:10
• Temperature = 55℃
• Time = 55 minutes
• pH = 4 – 5
Advantages and Disadvantages of Biopolishing:
➢ Depth of shade increases when enzyme treatment is
given before dyeing but the depth decreases when
enzyme treatment is given after dyeing.
➢ Wash fastness of the enzyme treated sample after dyeing
is good but wash fastness of the enzyme treated sample
before dyeing is very poor.
➢ One bath application saves energy, time and cost but the
bio-polishing effect is not as good as the two bath
method.
➢ Decreases the Pilling tendency.
➢ Loss in weight.
➢ Loss in strength.
Assignment
➢ “Wash fastness of the enzyme treated sample after dyeing
is good but wash fastness of the enzyme treated sample
before dyeing is very poor” Why ? Explain it in detail with
references.
