Value Additions in Textile Finishing – A Review
By: Prof. Tanveer Malik*, Prof. Ajay Joshi* and Prof. K. S. Sarkar**
*Faculties, Shri Vaishnav Institute of Textile Technology,
Shri Vaishnav Vidyapeeth Vishwavidyalaya Indore
**Sr. Lecturer, Shri Vaishnav Polytechnic, Indore
The garment industry’s new drive towards high value added products is prompted by increasing competition from other countries. Chemicals play a very significant role be it giving a class of touch through the effects colorful prints to soft handle, from easy care to nano finish and so on. Garment Industry is developing textiles with smart functioning using new chemical products to provide extra comfort and increased performance. For example, EASY CARE properties for garments which require minimum ironing and resist soiling and staining, ANTIMICROBIAL finishes for leisure and sportswear to prevent odor problems generated by bacteria and so on. With a shift to consumer centric thinking, trend in the supply chain, wherein it’s buyers and retailers with whom the decision making rests, process houses and chemical suppliers are constantly striving to innovate or develop new products/concepts for the market and some of these innovations are discussed in the paper.
KEY WORDS: Chemicals, Comfort, Garment, Innovation, Value Addition etc
Finishing is the final stage in the processing of fabric or garment before it reaches the customer or user. Finishing enhances the attractiveness and serviceability of the textile material. Finishing can broadly be divided in into chemical and mechanical finishing Categories. To make salable consumer products, the fibre, yarn, fabric or readymade garments have to go through various chemical-processing sequences such as preparatory, dyeing, printing and finishing. Among these the chemical finishing assumes considerable significance because the value addition is realized through functional finishing imparting the desirable properties.
VALUE ADDITIONS IN TEXTILE FINISHING:
NANO FINISH IN TEXTILES:
The German researcher Wilhelm Barthlott of the Bonn Institute of botany discovered, in 1990, that the lotus plant, admired for the resplendence of its flowers and leaves, owed this property of self-cleaning to the high density of minute surface protrusions. These protrusions catch deposits of soil preventing them from sticking. When it rains, the leaf has a hydrophobic reaction. Water rolls around as droplets, removing dust as it moves. Reproduced for nano technological process on the surface of woven fabrics, this self-cleaning property can be developed as a technological innovation. The fabric will have specific applications such as sails or certain garments. A self-cleaning cotton fabric known as nanao-care was developed and is marketed by an American Company, Nanotex and stain-resistant jeans and khakis are available since 1990. Nanocare fabrics are created by modifying the cylindrical structure of the cotton fibres making up the fabric. At the nanoscale, cotton fibres look like tree trunks.
Using nanotechniques, these tree trunks are covered in a fuzz of minute whiskers which creates a cushion of air around the fibre. When water hits the fabric, it beads on the points of the whiskers, the beads compress the air in the cavities between the whiskers creating extra buoyancy. In technical terms, the fabric has been rendered super-non wettable or super-hydrophobic. The whiskers also create fewer points of contact for dirt. When water is applied to soiled fabric, the dirt adheres to the water far better than it adheres to the textile surface and is carried off with the water as it beads up and rolls off the surface of the fabric. Thus the concept of “Soil-cleaning” is based on the leaves of the lotus plant.
UV protective finish:
The most important functions performed by the garment are to protect the wearer from the weather. However it is also to protect the wearer from harmful rays of the sun. The rays in the wavelength region of 150 to 400 nm are known as ultraviolet radiations. The UV-blocking property of a fabric is enhanced when a dye, pigment, delustrant, or ultraviolet absorber finish is present that absorbs ultraviolet radiation and blocks its transmission through a fabric to the skin. Metal oxides like ZnO as UV-blocker are more stable when compared to organic UV-blocking agents. Hence, nano ZnO will really enhance the UV-blocking property due to their increase surface area and intense absorption in the UV region. For antibacterial finishing, ZnO nanoparticles scores over nano-silver in cost-effectiveness, whiteness, and UV-blocking property.
Fabric treated with UV absorbers ensures that the clothes deflect the Harmful ultraviolet rays of the sun, reducing a persons UVR exposure and protecting the skin from potential damage. The extent of skin protection required by different types of human skin depends on UV radiation intensity & distribution in reference to geographical location, time of day, and season. This protection is expressed as SPF (Sun Protection Factor), higher the SPF Value better is the protection against UV radiation.
Characteristics of nano finishing in garments:
- Nano-processed garments have protective coating, which is water and beverage repellent.
- Their protective layer is difficult to detect with the naked eye.
- When a substance is manipulated at sizes of approximately 100 nm, the structure of the processed clothing becomes more compressed. This makes clothing stain- and dirt-resistant.
- Saving time and laundering cost.
- This technology embraces environmental friendly properties.
- Nano-materials allow good ventilation and reduce moisture absorption, resulting in enhanced breathability while maintaining the good hand feel of ordinary material.
- The crease resistant feature keeps clothing neat.
- Nano-processed products are toxic free.
- Garments stay bright, fresh looking and are more durable than ordinary materials.
- Manufacturing cost is low, adding value to the products.
Antimicrobial finish in textiles:
The inherent properties of the textile fibres provide room for the growth of micro organisms. Besides, the structure of the substrates and the chemical processes may induce the growth of microbes. Humid and warm environment still aggravate the problem. Infestation by microbes cause cross infection by pathogens and development odour where the fabric is worn next to skin. In addition, the staining and loss of the performance properties of textile substrates are the results of microbial attack. Basically, with a view to protect the wearer and the textile substrate itself antimicrobial finish is applied to textile materials. It is a well-known fact that the growth of bacteria and microorganisms in food or water is prevented when stored in silver vessels due to its antibacterial properties. The anti-bacterial properties of silver are now scientifically recognised. Silver ions have broad spectrum of anti microbial activities. The method of producing durable silver containing antimicrobial finish is to encapsulate silver compound or nano particle with a fibre reactive polymer like poly (styrene comaleic anhydride)
Necessity of antimicrobial finishes:
Antimicrobial treatment for textile materials is necessary to fulfill the following objectives:
- To avoid cross infection by pathogenic micro organisms.
- To control the infestation by microbes.
- To arrest metabolism in microbes in order to reduce the formation odour.
- To safeguard the textile products from staining, discolouration and quality deterioration.
Requirements for antimicrobial finish:
Textile materials, in particular the garments are more susceptible to wear and tear. It is important to take into account the impact of stress strain, thermal and mechanical effects on the finished substrates. The following requirements need to be satisfied to obtain maximum benefits out of the finish:
- Durability to washing, dry-cleaning and hot pressing.
- Selective activity to undesirable micro organisms.
- Should not produce harmful effects to the manufacturer, user and the environment.
- Should comply with the statutory requirements of regulating agencies.
- Compatibility with the chemical processes.
- Easy method of application. No deterioration of fabric quality.
- Resistant to body fluids; and resistant to disinfections/sterilisation.
INNOVATIVE VALUE ADDITIONS IN TEXTILE FINISHING:
It is a computer-controlled process for denim fading. This technique enables patterns to be created such as lines, dots, images, text or even pictures. In one version of this concept, a mask is used to give the desired shape that is to be applied on the fabric. The laser projects through a lens system, which expands the beam. This beam is passed through the shaped mask that comprises an aperture of the desired shape and is then deflected by a mirror to strike the textile substrate. The duration of exposure determines the final effect on the fabric.
The novelty of this system is that:
- It is water free fading of denim.
- It is an ecological and economical process.
- Excellent reproducibility and higher productivity.
- Being an automatic system, chances of human error are slim.
Ozone can react with aliphatic & aromatic bonds. For this reason it is possible to use ozone gas for anti-felting finish of wool, without treatment becoming economically significant. Polyester is easily damaged by ozone than polyamide, because polyester’s aromatic ring system can be easily oxidised & destroyed by the ozone. This could be termed as ozone fading. The appearance of oxidative bleaching of blue, red & yellow disperse dyes caused by the effect of atmospheric zone which is similar in appearance to gas fading. This effect is most common in acetate, triacetate & polyester dyes. Heat treatment of triacetate & polyester improves fastness to ozone fading.
Ozone fading can be prevented by using anti-(oxidation) ozonate softening agent such as diphenylenediamine (also uses as gas fading inhibitor) & p-octylphenol (which has no gas fading inhibitor), which means that using the method detailed here, ozone fading can be prevented. The slight high cost of employing this finish is more than recovered with the improvement of performance characteristics of the denim garment. Furthermore, anti-ozonates could be a good “marketing” tool too. By using technique, the garment can be bleached. Bleaching of denim garment is done in washing machine with ozone dissolved in water. Denim garments can also be bleached or faded by using ozone gas in closed chamber.
The advantages associated with this process are:
- Color removal is possible without losing strength.
- This method is very simple and environmentally friendly because after laundering, ozonized water can easily be deozonized by UV radiation.
This technique is most effective for small/medium size garment washing unit who can afford costly technology like sand blasting, etc. This technique is based on spraying/brushing the chemicals or pigments to get different effect on the garments. These techniques also save water, energy and time.
With advent of new technologies, the growing needs of the consumer in the wake of health and hygiene can be fulfilled without compromising the issues related to safety, human health and environment. Taping new potential antimicrobial substances, such as, Chitosan from nature can considerably minimise the undesirable activities of the antimicrobial products. Scientists all over the globe are working in the area and a few of them reported to have used antimicrobial finishes and fluoro chemicals to make the fabric having antimicrobial as well as blood repellant properties. Chitosan and fluoro polymers are reported to be most suitable finishing agents for medical wears with barriers against micro organisms and blood. To carve a niche for textile materials, this kind of value adding finishes are the need of the hour.
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- Encyclopedia of Textile
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