Author: P. Ganesan, L. Sasi kala
Functional fibers, Functional fabrics, Finishing treatments, Thermal, Regulation, Flame, retardance, Moisture, management, Easy-care, Self-cleaning, Insect-repellence, Antimicrobial, Ultraviolet protection, Radiation protection, Antistatic, Impact protection, Chemical protection. The scope of fibre science is very broad. Only innovative products will be able to open new markets and new horizons for the textile industry. Innovation is a key factor for operating successfully in any market. Within the textile industry, the challenge for companies today lies in bringing to market a stream of new and improved, value-added products, to strengthen existing product lines, and diversify into new areas. Technology represents one critical route in doing so. When textile assumes an additional function over and above the conventional purpose, it may be regarded as specialty or functional textile. Specialty finishes involves: Fragrance Release, Protective Finishes, Skin Care Additives, Insect Repellent, Deodorizing Fragrance, Antimicrobials, Flame Retardant Finishes, Cool Finish & Thermal Insulator Finish, Water Proofing Finish and UV Stabilizers. Functional finishes represent the next generation of finishing industry, which, make textile materials act by themselves. This means that they may keep us warm in cold environments or cool in hot environments or provide us with considerable convenience, support, and even fun in our normal day-to-day activities. Types of Functional Finishes, Antimicrobial Finishes, microbes are minute organisms, but can be most dangerous for creating harm to our lifestyle in different ways. So, to make the environment healthy, hygienic, and fresh, it becomes very important to have the control overgrowth of the microbes and for these the garments / fabrics should be treated with some specialty chemicals, which can restrict the growth of these microorganisms. Antimicrobial finishing is one of the special types of finishing given to the textiles where the chances of bacterial growth are high, and the safety is paramount. Antimicrobial treatment on the undergarments controls the growth of the microbes on it, which will in turn control the above effects. Characteristics of finishing inhibits the growth of microbes on the surface of the fabric, Maintains hygiene and freshness, stops bad odor,Controls or eliminates microbial staining, Improves life of the articles wherever it is applied, Improves hand of most of the fabric, Eliminates the chances of disease transmission, Effective on any substrate like cellulose, synthetics as well as their blends and any surface other than textiles, Aroma Therapy Fragma series/ Moisturizers/ Essential oils/ Aloe Vera, Microencapsulation of fragrances has been used to maintain a fresh aroma on the textiles. Aromatherapy provides potential benefits to the consumer through promoting a feeling of comfort and wellbeing. Different fragrances are used to stimulate different moods like, Relaxing/encouraging sleep, using fragrances for bedding and nightwear Muscle easing, applied to after sports activity garments, Uplifting/ head clearing for active sportswear, Clear thinking/confidence building by using fragrance applied to formal business wear. . Antistatic Finish, Static electricity is created when two non-conducting surfaces, such as synthetic textiles, rub together. The two surfaces become oppositely charged and as the rubbing continues, an electrical charge will build up, increasing in strength (voltage) until it can be discharged by contact or proximity with a conducting surface such as a metal radiator or door handle. This can be accompanied by a spark, and the wearer can experience the electrical shock, which is unpleasant, Static electricity also causes fabrics to cling, when two layers of clothing rub together, causing discomfort. Dry soiling of clothing: A further problem with static electricity is the collection or pick-up of fine particles of dust or ash by charged textiles. This can lead to unsightly marks on the fabric surface-active-static finishes: Although antistatic (metallic or carbon fibre) yarns are available for high-technology fabrics, for apparel use topical anti-static finishes are generally used, but these have several faults: they are either soft handling, but non-durable or are durable but with a very harsh handle. Bio-softening of Protein Fibers, Wool fabrics, both knitted and woven have a natural tendency to felt and shrink irreversibly. The commercial processes rely on chemical modifications and use chlorine or permono sulphuric acid to modify the fabric surface. Chlorination results in toxic AOX byproducts and hence it compelled the use of enzymatic treatment for shrink proofing. Protease can markedly reduce the AOX contents in effluents. It is found out that physical and chemical treatments should be combined with enzymatic treatment for shrink resistance of wool, such as peroxidizing wool with Potassium Permanganate and Ammonium Sulphate. Subsequently giving proteolytic treatment results in complete descaled fibers with enhanced softness and luster. High quality wool fibers can also be obtained by the application of heat resistant neutral protease that results in cashmere like feel. Protease pretreatment combined with chlorination or oxidative treatment using sodium hypochlorite or Potassium Permanganate and subsequently polymer application reduces the shrinkage area of wool fibre. Cool Finish (snocool), When temperature rises, we tend to sweat. This is a natural reaction of our body to maintain the temperature around 97″F. The sweat when evaporates, takes along with it heat equivalent to heat of evaporation of water, thereby maintaining the temperature of the body. The cool finish technology works in three different ways. The Snocool finish uses the moisture management route i.e., it will enhance the natural phenomenon of sweat evaporation. This finish absorbs and dissipates sweat evenly throughout and thus gives a cool feeling to the wearer. Snocool finish when applied to the fabric, reflects light and produces the cooling effect, moisture management / hydrophilic finish, ever since synthetic fibers became popular for clothing purposes, there has been the desire for a finish to change the hydrophobic character of these fibers. The main reason was to improve the wearing comfort. Hence the necessity to Improve synthetic fibers regarding their absorbency. Areas of textile finishing where improving the absorbency is still one of the main considerations are sportswear, some of which is also made with functional jersey with hydrophobic synthetic fibers on the inside and hydrophilic cellulosic fibers on the outside. The mode of action consists of the finest fibrilled microfibers (PES, PA or PP) transporting the moisture rapidly from the skin through the capillary interstices to the absorbent outer layer. In this way the textile layer of synthetic fibers next to the skin remains dry. After dyeing the hydrophobic synthetic fibers usually exhibits no absorbency. Only after application of a suitable hydrophilic agent can the material fulfill its function. This significantly increases the speed at which the moisture is spread to the hydrophilic outer layer and thus considerably accelerates drying. Flame Retardant Finish, Flame retardants are chemicals, which are added to combustible materials to render them more resistant to ignition. They are designed to minimize the risk of a fire starting in case of contact with a small heat source such as cigarette, candle, or an electrical fault. If the flame retarded material has ignited, the flame retardant will slow down combustion and prevent fire from spreading to other items. Since the term flame retardant describes a function and not a chemical class, there is a wide range of different chemicals, which are used for this purpose. Durability of flame retardants, non-durable finishes are not fast to laundering/washing and hence the substrates are to be treated after each wash. All earlier attempts, involving water-soluble chemicals, mostly inorganic salts, are applied on to fabric by immersion, padding or spraying. Durable finishes are durable to multiple launderings. These are more complex and difficult to apply. Semi-durable finishes have a level of durability to washing/laundering in between the non-durable and durable finishes. It also exhibits excellent fastness to dry cleaning using chlorinated solvents. Its application practically does not cause yellowing and modifies the handle of the articles. Peach skin effect. In classical finishing of lyocell, peach Skin effects are produced in rope form using Airflows and Air tumblers. Alternatives are produced in open- width finishing with special emery finishes. Here for example, emery papers coated with diamond dust are recommended which imitate effects comparable with the classical method. The peach skin effects can also be achieved with the treatment of cellulose enzymes where one does the fibrillation with alkali and later treatment with the cellulose enzymes that polish the fibrils to produce a peach skin permanent effect. Apart from Peach Skin effects, various finishes can naturally be applied to fabrics of Lenzing Lyocell such as calendaring, embossed effects, crepe or other special effects. The rmocat finishing, A finishing agent for producing heat retaining effect. this type of finishing when applied to the fabric keeps it warm. Produces heat retaining effect due to infrared radiation owing to its porosity. Especially suitable for 100% cellulose and its blends, UV Protective Finish, Another important function performed by garments is to protect the wearer from harmful rays of sun. The rays in the wavelength region of 150 to 400 nm are known as ultraviolet radiations. This wavelength region is further divided in UVC (100-280 nm), UVB (280-315 nm) and UVA (315-400 nm). The most important UV source is the sun and therefore almost every living organism is exposed to UV radiations. UVC radiations are absorbed by the ozone layer and do not reach the surface of the earth. Several types of UV stabilizers are available, the most common being benzophenones and phenylbenzotriazoles. These molecules can absorb the damaging UV rays of sunlight. Selection of UV Stabilizers, Factors to be considered in selecting an UV stabilizer includes, the substrate to be protected, Method and conditions of fabrication, The degree and type of protection desired, The size and shape of the finished product, The end use and environment during the use, Presence of other additives such as antioxidant, antistatic agents, colorants, filters, accelerators etc. Water / oil repellant finish, Wrinkle Free Finishes. By applying resins, it is possible to improve specific properties of cellulosic fibers. Examples are the improvement in crease recovery, dimensional stability, non-iron, reduced pilling and particularly with knit goods an improved appearance after several washes. For successful resin finishing it is essential that the goods are well prepared, and the recipes and processes are adhered to and monitored exactly. The wrinkle free treatment package comprises of a low formaldehyde resin, silicones, and polyethylene emulsion. This treatment involves chemical application of the elements comprising of this package through a cross linking effect that prevents the formation of creases and wrinkles which result in easy to iron fabric. Resins do however also have several effects on the fibers. Resins reduce the (tear) strength of cotton. The extent of the loss depends on a wide variety of factors: The amount and type of resin applied, the amount and type of catalyst, The curing conditions, The quality of cotton, The processes preceding finishing and possible damage etc., Tensile strength losses up 30-45% must be expected. For the so-called non-iron finishes, it is therefore often necessary to use qualities with a higher initial strength than for normal softening finishes. In this connection it should be mentioned that the tensile strength is not normally improved by the additives and softeners used. The tear resistance according to Elmendorf can however be influenced and maintained at the level of the unfinished goods or even improved by optimum selection of the softeners and additives.
