FABRIC SCIENCE
ASSIGNMENT -1
WRINKLE FREE FINISHING
SUBMITTED TO-
DR.CHITRAM MEENA
SUBMITTED BY
SHEFALI KUSHWAHA
SHOURYA TRIPATHI
What is finishing process
Fabric finishing is the general term for fabric finishing process.
Immediately after fabric is manufactured, it's raw and harsh and
not yet ready to be made into fabric goods. At this stage, the
cloth is sometimes called grey goods and it needs further
refinement. This is where fabric finishing processes become
important.
Wrinkle free finishes
Cellulosic fiber-containing fabrics are made wrinkle
resistant by a durable press wrinkle-free process which
comprises treating a cellulosic fiber-containing fabric with
formaldehyde, a catalyst capable of catalyzing the
crosslinking reaction between the formaldehyde and
cellulose and a silicone elastomer.
Why is cotton used ?
Cotton is suitable for apparel purpose because of its durability, good absorbency
and ability to take up a wide range of dyestuffs. However, during actual wear,
cotton garments are prone to crease under slight crushing, and the crease is
retained for a long time.
Why cotton creases?
Cotton is a crystalline fiber. Its polymer system is 70% crystalline and 30%
amorphous. Hydrogen bonds are the most dominant forces of attraction present
in the polymer system of cotton. The crystalline polymer system of cotton makes it
relatively inelastic. Bending and crushing of cotton textile materials places
considerable strain on its polymer system. This causes cotton textiles to wrinkle
and crease readily.
How to make cotton crease resistant?
Weak Hydrogen bonds get disturbed during the course of washing and on
drying they try to rearrange and reform giving rise to creases. To prevent
distortion of Hydrogen bonds, cross-linking has to be introduced in between
the H-H bonds, making the chains flexible.
What are resins?
Resins are cross-linking agents, which react with the OH groups of
cellulosic materials in acidic medium at a pH of 3–4 to form covalent
bonds. They are commonly used to make cellulosic fabric (cotton
and cotton blends) wrinkle resistant.
How resins work?
Resins work by the reaction of nitrogen atoms of each resin
molecule with the hydroxyl group of the cotton fabric. The reaction
forms a linkage between the resin and the cotton fibers giving the
cotton unshrink pattern in which shape is being made & cured.
Examples of resin
DMU : Dimethylol urea
DHEU : Dihydroxy ethylene urea
DMDHEU: Dimethyl dihydroxy ethylene urea
Advantages of Resin
Increase crease resistance and crease recovery.
Reduce the shrinkage during laundering.
Smooth and quick drying.
Improve handle and draping quality.
Improve weight and dimensional stability.
Increase strength of rayon.
It prevent intermolecular slippage in fiber core.
It become partially water proof and rot proof.
Resins mainly fall into two groups:
1. Cross linking type of resins
2. Deposition type of resins
Cross linking type of resins:
These types of resins chemically react with the fiber and crosslink the fiber
molecules. The type of finish obtained is durable and much better than
deposition type.
•DMU (Di methylol Urea)
•DMEU(Di methylol Ethylene Urea)
DMDHEU(Di methylol Di hydroxy Ethylene Urea)
Deposition type of resins
These resins are deposited on the fabric as surface
coating. No reaction will take place between the
fiber and resin.
They include:
•Alkyd resins
•Ketone resins
•Urea formaldehyde resin
•Phenol-Formaldehyde resins
• Vinyl resins
Mechanism of Resin finishing
• Pad the fabric with resin : Applied with chemical
liquor form. Usually on Padding Mangle.
• Drying the fabric:
• Dry the fabric with chemicals. The temperature of
drying is vary with resin.
• Curing the fabric:
• It React chemically with cellulose hydroxyl
compound and make cross linking at high temperature.
Polymerization and cross linking occur at this stage.
Padding
Before impregation, the material should be scoured and bleached for
better penetration of liquor.
The fabric is padded by using either two or three bowl padding mangle
with an expression of about 80% at RT.
After padding the material is dried in stenter with minimum tension at
(70 degree – 80 degree) C.
Curing
• After drying, the material is cured at (120 degree – 150 degree) C for 2-5
mins. In a high temperature slenter machine.
• Cross linking and polymerization takes place during curing process.
Washing and Soaping
After curing the material should be washed in open width or
rope form in a dilute solution of soap and soda ash.
The purpose of this washing is to neutralize the residual
acidity and also to remove any combined reagent which
causes undesirable effect.
Types of Wrinkle Free Process
• Pre- Curing
• Post- Curing
• Dip- Spin
• Vapor – Phase
Pre- Cured fabric:
Fabric can be a 100 % cotton fabric or cotton blend.Contrary to all the other WR
processes, by this system the fabric does not need any further heat treatment
as the curing process has been done already before the shirt is manufactured.
The already finished fabric is resistant to wrinkles already
Post- Cured fabric:
After the shirt is manufactured, it has to be pressed entirely. After it has been
put on a hanger it will be cured in a hanging position on a cloth rack inside an
oven for 3- 5 min. by about 130°C to 150”C (depends on the chemical used).
Dip- Spin system:
After the shirt is manufactured as usually, it will be dipped into a mixture of
chemicals, which will be absorbed by the cotton fibres. After the treatment in a
tumbler the shirt is still moisturized and has to be pressed entirely. Important is,
that during the pressing operation on the various Veit- Kannegiesser Collar-,
Cuff- and Body- Presses, the curing process will start already.
Vapor – Phase:
Similar to the DIP SPIN system the shirt is manufactured as usually. After the
final pressing, a special curing oven is used as instead of liquid chemicals, gas is
used to make the shirt resistant to wrinkles
Chemical process of wrinkle free fabric
The crosslinking agents that result in the permanent press finish are
often derivatives of urea. Popular crosslinkers include DMDHEU
(dimethylol dihydroxyethyleneurea) and DMEU (
dimethylol ethylene urea).
The permanent press effect arises from crosslinking of molecules of
cellulose by chemical agents such as DMDHEU.
Washing and drying machines
In older washing machines, the permanent press setting sprays
moisture during the spin cycle to maintain the moisture content of
the permanent press fabrics above a certain specified limit to
reduce wrinkling. Most older clothes dryers feature an automatic
permanent press setting, which puts clothes through a cool-down
cycle at the end of the normal heated drying cycle. Modern dryers
tend to include this as a standard feature.
Another solution
In the 2000s, fabric softeners were launched to provide more
resistance to external stress and wrinkle recovery, which can be
improved by spraying fabrics with aqueous emulsions made with
vegetable oils. The sprays allow the fibers to slide closer to each
other, helping them hold their shapes.
Advantages of Resin finishing
It improves the Crease Resistance and Crease
Recovery property
It reduces the shrinkage during laundering
It gives a smooth and quick drying property
It improves Resilience, Handle and Draping
quality
It improves the weight and Dimensional stability
Disadvantages of resin finishing
• Environmental effect — release of free formaldehyde
• It decreases the Tensile strength and Tear strength
• It decreases the Abrasion resistance
• It gives an unpleasant odour
• It gives harsh and stiff feel
Applications of wrinkle free finishes
Mainly it is done on these fabrics:-
Cotton
Linen
Reference
1. Retrieved From:
http://ezinearticles.com/?Wrinkle-Free-Garments&id=367052
2. David Grosz. February 12, 2007. Why Do Clothes Wrinkle? Slate
Retrieved From:
http://www.slate.com/articles/news_and_politics/explainer/2007/02/why
_do_clothes_wrinkle.html
3. Saurabh. December 1, 2010. Resin Treatments: Giving Value addition to
Vintage Denim garments. Denims and Jeans.
Retrieved From:
http://www.denimsandjeans.com/denim/manufacturing-process/resin-tre
atments-giving-value-addition-to-vintage-denim-garments/
