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.

1. Textile chemical
processing
Finishing

2. MECHANICALASPECTS OF
CHEMICAL FINISHING
1 Chemical finishing
Padder
Coating
2 Mechanical finishing
Rollers

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.

6. Wet vs. Dry Cross Linking

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%

9. Typical Recipes for 100%
Cotton

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

13. Relationship between Oil Repellency
and Length of
Perfluoroalkyl Side Chain

14. Flame retardant of various
fibre

15. Process of burning of fibre

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;

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

23. Soil release

24. Compounds used for soil
release finish
 Polymethacrylic Acid PMAA
 Methacrylic Acid - Ethyl Acrylate Co-Polymers
 Fluorochemical Soil Release
 Non ionic detergents

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

28. Mechanical finishing
 COMPACTING – SHRINKPROOFING
 Sanforizer

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.