Nikhil Yogesh Upadhye
Department of Textiles (Textile Chemistry)
DKTE’S Textile and Engineering Institute, Ichalkaranji, India
Intern at Textile Learner
Email: nyupadhye@gmail.com
Introduction
“Value Added Product” has become a buzzword in the world economy as a result of rapid liberalization and globalization. It is now impossible to survive in this highly competitive world market unless a product is characterized by value addition. With the World Trade Organization (WTO) entering into force on January 1, 2005, stiff and fierce competition in the global marketplace is unavoidable. To meet this challenge, we have no choice but to produce a value-added product, or else we will perish. To make salable consumer products, however, the fiber, yarn, fabric, or readymade garments must go through a series of chemical processing steps, including preparatory, dyeing, printing, and finishing. Among these, finishing takes on a significant role because value is added through functional finishing, which imparts desirable properties.
1.1 Wrinkle free finishes: Clothing’s primary function is to keep body heat in while allowing sweat to pass through to the outside atmosphere. These characteristics, combined with hydrophobicity, resistance to static charge generation, and a pleasant natural feel, make it an excellent tropical fiber. Cotton, on the other hand, has one of the most significant drawbacks: it is prone to creasing during wear and washing. Cotton is treated with a cross-linking agent to give it wrinkle-free properties. Resin finishing is the term for this procedure. The strength is reduced to an unacceptable level when the desirable properties are imparted at attractive levels. A favorable balance of wrinkle resistance and mechanical properties s achieved and hence it has become commercially successful.
There are different routes for imparting wrinkle free properties. They are:
Pre-cure and post-cure processes.
Dip and tumbling process.
Typical application recipe is,
Cross-linking agent: 40-120 gpl
Magnesium chloride: 10-25 gpl
Citric acid: 0.3 gpl
Softeners combination: 40 gpl
Wetting agent: 1 gpl
Acetic acid (pH): 4 – 4.5
Normally cross-linking agents are applied by Pad-Dry-Cure method.
The steps involved are,
Impregnation of the fabric in the prepared resin solution by padding.
Drying the padded fabric in stenter with minimum tension at 70 to 80ºC.
Curing at 120-150ºC for 2 to 5 min. in stenter where cross-linking and polymerization takes place.
It is then washed with 1-2 gpl of wetting agent and 2-4 gpl of soda ash at 50-60ºC for 10 min.
1.2 Softening:
The introduction of novel poly-siloxane softeners in both micro and macro emulsion forms has been the most significant change in the softener field. Cotton has an ultra-soft handle thanks to softeners and elastomers based on epoxy and amino functional poly-siloxanes. Currently available silicone softeners can be classified into the following classes.
Non-reactive.
Reactive.
Organo-reactive.
Non-reactive silicones are made up of poly-dimethyl siloxanes and have short-term properties. Polydimethyl siloxanes polymers modified with silane hydrogen or silanol functional groups are known as reactive silicones. The durability is superior to that of non-reactive materials. Organo-functional silicones improve the orientation of amino-functional silicones, resulting in an extremely soft handle that is often referred to as super-soft. Silicone Softeners Are Environmentally Friendly: Silicones are a minor component of the waste water treatment plant’s discharge. In the form of tiny dispersed droplets attached to suspended solids, PDMS enters the plant waste water stream. The silicone in the sludge is converted to amorphous silica, water, and carbon dioxide when it is burned. If sludge is used as a fertilizer, it may introduce PDMS into the soil, where it will degrade naturally.
1.3 Water resistant breathable finish:
The current trend is to impart water repellency to fabrics and garments without affecting water vapour permeability for use in outdoor activities, weather-clothing, and so on. In sports where the relative metabolic rate is high, improving the rate of perspiration transpiration through the textile material is especially important. Water-resistant breathable finishes are impervious to water droplets while allowing water vapor to escape. Such types of garments are designed for sportswear, track suits, clothing for mountaineering, etc.
The chemicals consist of Quaternary Ammonium Salt with the Pyridine Base and a compound is formed with cellulose in the presence of sodium acetate.
The process sequence employed is Pad-Dry-Cure-Soap-Rinse.
Padding – Water repellent chemical
Drying – 60 to 70ºC
Curing – 120ºC for 2 to 3 min.
Soaping – Soap 0.2%, Soda 0.1% at 35ºC for 1 to 2 min.
Stearoxy – methyl pyridinium chloride is popularly used for durable water-repellent finish as it reacts chemically with the fiber.
1.4 Water, stain and oil repellent finish:
As the name suggests, the finishes are given so as to resist the action of staining. They show a good resulting feature of resisting the dirt particles or else avoiding dirt to remain over the surface. Our fabrics tends to get soiled because of reason or the other. The main reasons of these are either encountering with certain stains accidentally or of other reasons. As an owner, one wants that such of the stains should be removed off and hence the appearance of the fabric remains as pleasing as before. Hence due to these phenomena, they are much demanded in the market.
Fig: Water and oil repellent finished fabric
The other main advantages of nanotechnology over dirt repellency are as follows:
Durability: This finish withstands more than 50 washes.
This finish improves the hydrophilic property of synthetic materials.
Easy Application technique: pad – dry – cure.
Fig: Stain repellent finished fabric
2. Biological Finishes
2.1 Bio polishing finishes: A new wave of biotechnology is emerging with the rapidly increasing use of enzymes on textiles. Enzymes are naturally occurring proteins that have the ability to catalyse specific chemical reactions. Cellulases are the most commonly used enzymes for creating wash down effects, faded looks, feather touch finishes, and so on. The cellulase family includes acid cellulase, neutral cellulase, and hybrid cellulase. Bio Polishing is a process in which the specific cellulase enzymes acts on the yarn surface of cellulosic fabrics to improve their surface characteristics by conferring following properties:
Cooler feel – brighter luminosity of colors.
Softer feel – more resistance to pilling.
All these fabric characteristics are the result of the hydrolytic action of the soluble enzyme over an insoluble substrate like cellulose.
Biopolished effects produced by cellulases are:
Acid cellulase
Neutral cellulase
Hybrid cellulase
pH
4.5 – 5.0
6.0 – 7.0
5.0 – 6.5
Temp (ºC)
60
50
50 – 60
Degree of Abrasion
High
Moderate
High
Back staining
High
Very low
Moderate
Special effects
Wash down effect
Salt and pepper effect
Wash down effect
Biopolishing can be done at any point during the fabric’s wet processing, but its best done after it’s been bleached. Because the treatment is a reaction rather than a coating, the surface modifications are permanent. The small fibrils protruding from the surface of the cotton fiber are weakened, allowing them to easily break off, resulting in a smooth fiber surface. Even after repeated wear and laundering, bio polished fabric retains its new appearance and feel.
2.2 Leather finish:
Polyurethane softeners provide an elastic handle and a characteristic rubbery touch that is long-lasting. To ensure adequate storage stability, softeners based on special reactive polyurethane are marketed by blocking the reactive iso-cyanate groups. They’re used in a 2.5 % o.w.f. mixture. Prior to the application of polyurethane softener, which is typically used on fabrics dyed other than indigo, an enzyme wash is performed.
2.2 Rubbery touch:
Rubber latex provides a glossy, crispy handle with a distinctive rubbery effect that is long-lasting. This effect is becoming increasingly popular, and it is used as a final finishing treatment after an enzyme or stone wash, or after mechanical abrasion and an enzyme treatment.
2.3 Micro encapsulation finishes: Microencapsulation is a fascinating process that involves wrapping tiny droplets or particles in a protective coating, resulting in CAPSULES for a variety of applications. A capsule is a small container that protects its contents from evaporation, oxidation, and contamination until it is triggered to release them.
2.4 Fragrance finishes:
These are microencapsulated fragrance formulations such as musk, pineapple, rose, lavender, jasmine, lemon, peppermint, and others that are applied to fabric using a binder. When used in this manner, they give off a pleasant scent.
Recipe: To impart the desired fragrance, the fabric is treated with
3.1 Insectrepellent finish:
Menthoglycol is a natural insect repellent active ingredient derived from the natural and renewable source of lemon eucalyptus. This was tested moderately with an aggressive mosquito cage population, and there were no bites for at least 4 hours. This means the product has a high level of repellency.
3.2 Antimicrobialfinishes:
The majority of Americans are aware of germs in their daily lives. A bacterial-inhibition finish developed by INTERA CORPORATION in the United States and marketed by Clarient in India. They’re used on sports textiles, underwear, uniforms, workwear socks, surgical draps, and medical and technical textiles, among other things. Then apply part rapid drying to garments, depriving bacteria in the textile and on the body of the moisture they require, and thus inhibiting bacterial growth.
Clothing and textile materials serve as carriers for microorganisms as well as growth media for pathogenic and odour-producing bacteria. Skin diseases are caused by bacteria and fungi. The production of antimicrobial finished fabric is in high demand due to the growing demand for clean and hygienic textile goods. Microbes are microscopic organisms that can be extremely harmful to our way of life in a variety of ways. So, in order to keep the environment healthy, hygienic, and fresh, it’s critical to keep microbes under control, and to do so, garments and fabrics should be treated with specialty chemicals. Antibacterial agents in the finishing recipe include biquanides, phenols and their derivatives, isothiazolones, metals, ammonium compounds, and alcohols. Other important chemicals include Zeolite (a sodium aluminose inorganic compound), Triclosan (a phenolic derivative), Chitin (extracted from crab and shrimp shells), and Quarternary ammonium compounds.
Recipe: Pad the fabric through aqueous dispersion of 1% Silver and Silica-alumina-mica powder for 30 min. at 90ºC, fabric obtained has 100% bacteria extinction capacity.
Alternatively, the mercerized fabric can be padded with an aqueous solution containing 50g 5% N-[(fluorodichloromethyl) thio] phthalamide, 100g of 30% Ashiguard AG710 and 50 gpl of 80% polyether-polyurethane.
3.3. Skin care active ingredients for fabrics:
Aloe Vera and Vitamins produce the following effects bacteria, Static effect, Anti-inflammatory effect, Moisturizing effect, Regenerates and promotes suppleness of the skin, Protects, etc. and cares for the skin, beneficial effect on the blood circulation.
4. Mechanical Finishes This category includes machines that focus solely on mechanical aspects of fabric processing, such as controlling vibrations, frictional forces such as abrasion on fabric surfaces with emery, brushes, grooved shaped rough rolls, differential fabric speeds, and so on. The following items are included in this set of finishes:
4.1 Raising finishing:
Soft and Supple Handle is one of those effective tools that has helped elucidate the definitions of fabric value added requirements. As a result, raising entails lifting fibers to a significant height in order to prevent fabric construction disruption. Fabric is moved over a central drum mounted with a series of pile and counter pile rollers that move in such a way that each fiber is lifted in a controlled manner.
By loosening a large number of individual fibers from the fabric and subsequent raising and napping in order to crest a dense raised fabric/surface, this finishing work is used to create a different feel and a velvety material surface on fabrics and knitwear.
4.2 Peach finish: This type of mechanical finish gives the fabric a soft and elegant feel, boosting its value to a higher level. The machine that is used to apply the peach finish is made up of a number of emery rollers that are arranged in such a way that when a fabric is passed through them, the surface fibers are slightly lifted up, resulting in a soft and supple finish.
4.3 Sueding finishing:
This is done on a cloth or knitted fabric’s surface. The fabric is covered by a thin pile during emerizing, which does not harm the machine or the fabric’s structure. The effect is determined by the fabric’s structure, yarn, and surface. The pile is lighter and easier to obtain when the yarn fibers are shorter and thinner. For mechanical variation of surfaces, two types of machinery are usually available: a mutual roller machine and a sanding machine. Fabric is tensioned over four to seven rollers with emery paper rollers that turn in the opposite or opposite direction of the fabric in the first case. In this way, adjustable pressure creates friction between the fabric and the emery surface. With emerizing any protruding fiber splits and results in velvety but nonetheless fiber pile.
4.4 Lisa:
This finish combines several finishing processes. The substrate is dampened and then beated with mechanical spokes to loosen it up. It is then exposed to a nylon bristle roller rotating at a high speed, which causes the surface fabric to become hairy, and it is then peached as described above. This finishing method can be used as a powerful tool for promoting a higher-value final product.
4.5 Foiling: When fabric is passed between two adjacent rollers, this is a pure mechanical finish that includes transferring foil engraved on to a roller. The nipping action involves transferring foil from one roller to the other, which is surfaced with fabric, through the deliberate action of pressing the foil onto the fabric.
5. Thermo-Mechanical Finish
5.1 Plasma technology:
Concept of plasma:
Plasma is a partially ionized gas containing ions, electrons, neutral species and UV/Visible radiation. Generally there are three states normally namely as solids, liquids and gases. Plasma is the fourth state of matter. Plasma treatment is regulated by three features namely Temperature, Pressure and Voltage.
Application techniques:
Glow discharge.
Corona Discharge.
Applications of plasma treatments:
Wet ability of filter material (paper and synthetic)
Medical textiles and blood filters Fibers.
Automobile textiles.
Work wear.
Fibers for structural composites (building, sportswear) foils.
Packing material and foils.
5.2 Calendering: Calendering belongs to thermo-mechanical type of finish. Though this one of the old types of finishing method yet it holds sheer importance in finishing department. Here fabric is passed in an open width form over a series of consecutively roller placed vertically in such a manner that considerable amount of tension is provided to the fabric. Rollers over which fabric is placed is incorporated with steam which results in improving lustre of fabric after calendaring
Conclusion:
Due to aesthetics and product value addition, these finishes are now catching up. Season, fashion, and its cycle have a direct relationship with the industry to which they are attracted. As a result, a manufacturer’s ability to produce deserved value for his work will be nearly impossible until sufficient emphasis is placed on delivering a sufficient amount of input to satisfy all of the above aspects. As a result, it proves that in today’s environment, if one wants to stay afloat in a sea of competition, one must develop value-added techniques. This is backed up by the proverb “SURVIVAL OF THE FITTEST.”
References:
Latest machinery giving mechanical finishes for garments, Dr.G.P.Nair, Colourage, Texindia fair special, 2-4 Nov 2001, pp 69 -79
Encyclopaedia of Textile
Denim Washing and finishing: A review, Purushottam De, MMTI, March 1998, pp 129 – 131
Flocking technology, AATCC symposium on Lamination and Coating 1996. pp 83-92
Past, present and future of jeans and denim fashion garments, Yasini Nensey, Clothes line July 2002, pp 78-80
Encyclopaedia of Textile (Volume I, II, III)
“Developments in silk finishing” Colourage annual 2003.
NCUTE Pilot Training Program on “Finishing of Garments and knit goods” 27TH TO 29TH Sept. 2003.
“Textile finishing” authored by Nalankilli
“Culp finishing : new technique for the home fabrics market” International Textile Bulletin, March 2001
“Developments in ecofriendly finishes” New Cloth Market, Dec.2003.
Founder & Editor of Textile Learner. He is a Textile Consultant, Blogger & Entrepreneur. He is working as a textile consultant in several local and international companies. He is also a contributor of Wikipedia.
Very nice and informative.