1. WRINKLE RESISTANT FINISHING
OF TEXTILES
By Richa Kumari
B.Des, Sem – VII
Textile Finishing
Silpa– Sadana
Visva Bharati University
October 05, 2020.
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2. INTRODUCTION
Finishing of the textile material is the final operation
performed to enhance the aesthetics and improve the
functional characteristics of the textile materials.
In today’s time, everybody wishes to look perfect with their
dress and attire. And so the demand for wrinkle resistant
finish has increased as it provides wrinkle recovery property
to the fabric and garment.
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3. WRINKLE RESISTANT FINISHING
The main objective of wrinkle resist finish is to impart wrinkle
recovery property to the textile material.
This finish is also known as durable press finish.
Advantages:
•Provide smooth appearance.
•Maintain dimensional stability of the material.
•Make the fabric resistant to the formation of crease.
•Durability increases.
Cellulosic fibres have the tendency to crease the most.
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4. Extension
Compression
Fabric/ fibre
WHY DOES A FABRIC CREASE?
Whenever any textile material is bent,
• an extension zone and a compression zone are created.
• Development of some stress and strain, due to this
extension and compression.
• Sharpness of the bent is the reason behind the formation
of crease.
• Sharp bend, intermolecular bond break.
• Crease form.
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5. • In case of cotton, intermolecular bond is Hydrogen bond which
is a weak bond, and so it breaks easily resulting in the crease
formation.
MECHANISM OF WRINKLE RECOVERY FINISH
• Crease formation occurs due to the breakdown of weak
intermolecular bonds.
• A strong intermolecular bond is required.
• bonds can compress, stretch, bend, stressed but will not break.
• A covalent bond, also called as covalent crosslink.
Naturally, if covalent bonds are not present then we need to
create them.
• Cross linking agent is required.
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6. CROSS LINKING AGENTS
Urea based cross linking agents:
1. DMU (Dimethylol urea)
When urea and formaldehyde condensates it gives us a
compound called DMU.
This DMU when reacts with cellulose forms covalent bond.
Limitations of DMU-
• Fishy odour due to the release of formaldehyde.
• Stiffness increases due to self polymerizing property of
DMU.
• Chlorine retention (degradation might occur in the fabric)
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7. 2. DMEU (Dimethylol ethylene urea)
Somewhat similar to DMU, cyclic compound.
• In this case, no labile hydrogen is present, so chances of
chlorine retention minimize.
• Less stiff.
• Release of formaldehyde is less. So, fishy odour will be less.
Limitations of DMEU- Hydrophobicity
3. DMDHEU (Dimethylol dihydroxy ethylene urea
• Cyclic compound, prepared from urea, glyoxal and
formaldehyde.
• Durable and stable.
• Hydrophilic in nature.
• DMDHEU has high crease recovery angles but show a
tendency of yellowing on curing.
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8. Drawbacks of formaldehyde containing cross- linking agents:
• Harmful for the human body as well as the environment.
•Loss in tensile strength and tear strength.
•Gives an unpleasant odour due to the release of formaldehyde.
•Reduces abrasion resistance.
• Harsh feel.
CATALYSTS
Types of catalyst for forming this type of covalent bonds are:
•Free acids – Citric acid
•Latent acids - MgCl2, ZnCl2
•Mixture of acid and salts – Glycolic acid
•Phase separation type – Magnesium dihydrogen phosphate
•Self limiting type – Sulfurous acid
•Chlorohydroxides – AlCl3
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9. PROCESS OF APPLICATION
1. Exhaust process
2. Pad dry cure process
• For wrinkle resistant finish, Pad- dry- cure method is preferred
generally as we are interested in dimension control also.
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FORMALDEHYDE FREE CROSS LINKING AGENTS
• DMeDHEU and BTCA (Butane tetra carboxylic acid)
• PCA (Poly carboxylic acid)
• Knittex RCT, Texicil DC, Arkafix ELF, Arkafix NEC - Trade names
• Citric acid is also used for providing crease resistance. Yellowing
problem can arise, with the use of citric acid as a cross linking
agent.
Advantages: Eco- friendly, no risk to human health, as it is free
from formaldehyde.
10. STEPS INVOLVED
•Padding with an expression of about 80% in the two or three
bowl padding mangle.
•Drying at a temperature of 700 C- 800 C in the stenter.
•Curing (1200 C- 1500 C) in the stenter.
•Washing and soaping
•Softening
•Drying
CREASE RECOVERY ANGLE (CRA/ WRA)
• For a woven fabric,
CRA = Warp angle recovery + Weft angle recovery
• For a non- woven fabric, CRA can be figured out from the
machine direction and cross to the machine direction of recovery.
• And for a knitted fabric, CRA is the sum of angles of recovery in
Courses and Wales.
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PERFORMANCE CHARACTERISTICS OF WRINKLE
RESISTANT FINISHING
1. Crease recovery testing
Effect of add-on (%)
Measured by taking the initial weight of the fabric and after pad-
dry- cure process, weight is noted. The difference in the weight
gives the add-on weight.
If we increase in add- on, crease recovery should increase.
DP rating (Durable Press)
DP rating is after- wash appearance of the fabric.
It can be measured by comparing with plastic replicas assigned by
standard organization such as BIS, AATCC, and ASTM indicating
grade 1-5 on a scale.
• Grade 5: very smooth, pressed, and finished appearance
• Grade 1: crumpled, creased and severely wrinkled appearance.
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2. Bending length testing
Bending length testing is a measure of stiffness of any fabric.
After wrinkle resistant finish, the stiffness of fabric will increase as
intermolecular resistance is created by the formation of covalent
bonds.
3. Tensile strength testing
• Curing temperature
• Acid environment during curing
• Cross- linking: It is believed that cross linking increases the
strength of a material. But the situation is different for different
fibres. Wet tenacity of cotton is higher while wet tenacity of
viscose is lower.
So, in case of cotton tensile strength will reduce.
And in case of viscose tensile strength may increase.
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4. Abrasion resistance test
If tensile strength reduces then abrasion resistance will also
reduce because degradation is taking place.
PERMANENT PRESS
In some cases, crease is desired by the customer/ consumer.
Such type of finishing with crease is known as permanent
press.
Examples- In trousers, skirts (school uniform), etc
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CONCLUSION
Different processes are performed while preparing a textile
material to achieve certain properties. Wrinkle resistant finish
is one among them. This finishing process not only imparts
crease recovery property to the textile materials but also
improves their handle property and makes them appear softer.
It also adds value to the products.
DMDHEU is the widely used cross- linking agent for this
finishing. DMeDHEU, citric acid are now coming into use.
Every process has its own advantage as well as drawbacks, so is
with wrinkle resist finishing. On one hand it provides wrinkle
recovery property to the fabric, on the other hand it reduces
tensile strength, tear strength and abrasion resistance. But we
should focus more on the utilitarian part of the finish, keeping
an eye on how to reduce its drawbacks and harmful effects.
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REFERENCES
•http://textilelibrary.blogspot.com/2009/03/wrinkle-free-
finishing-process.html (accessed on 21.09.2020)
•https://youtu.be/g7nuo4lYMJU (accessed on 21.09.2020)
•https://youtu.be/sU9MjNF0-Qs (accessed on 22.09.2020)
•https://indiantextilejournal.com/articles/fadetails.asp?id=2635
(accessed on 23.09.2020)
•https://www.fibre2fashion.com/industry-article/3413/role-of-
silicone-in-resin-finishing (accessed on 23.09.2020 )
•https://www.slideshare.net/ShubhamSingh527/wrinkle-
resistant-finishes-in-textiles (accessed on 23.09.2020)
