Mechanical finishing of cotton. Stiff, soft, wrinkle resistant, water repellent, flame retardant and enzyme (bio-polishing) finishing of cotton; Milling, decatizing and shrink resistant finishing of wool; Antistatic and soil release finishing; Heat setting of synthetic fabrics; Minimum application techniques; Pollution control and treatment of effluents.
3. Easy Care/ Durable press /
Wrinkle free/Cross Linking
Finish on Cotton
Why does cotton wrinkle?
Creasing occurs due to the inelastic nature of
the fiber & the change that occurs as the
material goes from dry –wet-dry state.
CR is dependent on elastic recovery from
extension and not compression.
Lack of memory effect
4. Role of water in crease formation
Swelling in water leads to –
breaking of intermolecular hydrogen bonds in
cellulose and formation of H bonds between water
and cellulose. Hydrated polymer chains slide past
each other more easily and at lower strains.
Creasing and shrinking of fabric to release internal
stresses. As it dries, hydrogen bonds form in the
new deformed (wrinkled) state.
Wrinkle resistance is the property of a fabric which
causes it to recover from folding deformations.
5. Effect of cross linking
Enhanced Dimensional stability
Reduction in swelling and shrinkage
Improved sheen and hand (calendering)
Improved dry and wet wrinkle recovery
Smooth drying
Retention of intentional creases and pleats.
7. Evaluation of Easy care finish
1.Durable press rating–Quantifies the after
wash appearance of fabrics by comparing the
resulting surface appearance of washed , died
and conditioned samples with standards. (>3.5)
2.Wet and dry crease recovery –Greater the
CRA better it is. ~320.
8. Effect on Properties
Crease Recovery
Stiffness
Moisture Regain
Dimensional stability
Shrinkage
Tensile and tearing strength
Abrasion resistance
Pilling tendency
For every 10% increase in CRA, the tear and abrasion
strength is lost by 7%
10. Water repellent finish
Repellent Finishes
For fabrics to be water repellent, the critical
surface tension of the fibers surface must be
lowered to about 24 to 30 dynes/cm. Pure water
has a surface tension of 72 dynes/cm so these
values are sufficient for water repellency.
11. Water repellent compounds
Paraffin Waxes
Pyridinium Compounds
Metal Complexes
SILICONE WATER REPELLENTS
FLUOROCHEMICAL REPELLENTS
17. Chemical compounds used
for flame retardency
Boron
Boric acid and borax
Phosphorous and nitrogen
Halogens
18. Antistatic finishes
Static charge generation
Problem in processing –fabrics move at high speed and
there is friction generation
Yarns, fabric plies repel each other.
Consumers face clinging problem
Electric shocks on carpets
19. Requirements of Antistatic
agents
Be easy to apply
No effect on dyeing
Heat resistant-should not decompose, vaporise or
diffuse
Low toxicity
Not cause yellowing
No increase in soiling
Good wash and abrasion fastness.
20. Principle of antistatic activity
Increase surface conductivity (better charge dissipation)
eg. Polymeric compounds that form a hygroscopic layer
on the surface.
Reduce frictional force ( decrease initial charge build
up) eg. Surfactants and lubricants;
21.
22. Other approaches for Antistats
Dispersing carbon particles in polymer melts.
Depositing carbon
Depositing metallic coatings(Ni, Cu, Ag)
Blending with fibres from SS, Al or other
metals
All of the above have a dark or black
appearance
24. Compounds used for soil
release finish
Polymethacrylic Acid PMAA
Methacrylic Acid - Ethyl Acrylate Co-Polymers
Fluorochemical Soil Release
Non ionic detergents
25.
26. Minimum application
techniques
High WPU
Leads to migration during drying.
Non uniform distribution of chemicals and dyes.
Very low WPU
Uneven finish distribution
Liquid phase is discontinuous
Wet on Dry Methods
Wet on Wet Methods
27. Various finishing techniques
Engraved roll
Kiss roll
Loop transfer
Foam technique
Spray applicator
Coating
Lamination
29. Calandaring
Calendaring is a process where fabric is compressed by
passing it between two or more rolls under controlled
conditions of time, temperature and pressure. A calendar is a
machine consisting of two or more massive rolls which are
compressed by means of hydraulic cylinders applying
pressure at the journals.
Chasing
Embossing
Swizzing
Friction
Schrienier
30. Decating
Decating is normally the last finishing process for some
fabrics. It is a method of steaming fabric between two layers
of cotton press cloths. The process is used to:
1. improve the hand and drape,
2. brighten the colors and enhance natural luster, assist in
setting the finish, or refinish fabrics after sponging or
cold water shrinkage.
Decating is a normal step for many wool and wool blend
fabrics. It is an effective mechanical softening treatment
resulting in a luxurious, soft, smooth handle. The process is
also effective on acetate, acrylic, rayon, spun polyester and
other synthetic blends.