New frontiers in chemical processing of textiles

  C.N.Sivaramakrishnan BSc Tech C Col FSDC     
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Textiles are present everywhere in daily life. With the wide range of innovative textiles being developed and introduced today, there is an increased recognition of the importance of textiles as building block materials for new product development. Over the past five decades, the textile industry has witnessed unexpected growth in newer fibers (particularly synthetic fibers), spectacular developments in machine engineering, coupled with large scale applications of electronics and information tecgreen_chemistry_580X330+hnology. Fiber and textile processing facilities have also undergone enormous improvements in automation and simplification. Micro fibers and nano fibers have become the order of the day. The benefits of nano and bio technologies are made use of in up gradation of chemical finishes.

Role of specialty chemicals

Specialty chemicals play a significant role in the production of fibers and textiles. Specialty chemicals can be defined as a group of relatively high value low volume chemicals known for their end use applications and or performance enhancing properties.  Awareness of chemical reactions, polymer sciences and understanding complex biochemical reactions have resulted in what we see a dramatic shift in the minds of a processor.  New chemical technologies have played a pivotal role in maintaining the growth of textile chemicals in accordance with legislation on health, safety and environment which is fast emerging.   A niche in this segment is the textile wet processing chemicals that can help lower the cost of textile chemical production effectively. Rising quality specifications accompanied by increasing cost pressure makes for a very challenging situation for textile processors and the textile industry as a whole.

There is tremendous pressure to deliver textile auxiliaries at low cost. Continuing the decade old trend of having the strongest growth in the textile industry, the textile chemicals manufacturers have now come up with unique ideas for making  the textile chemicals available in the concentrated form there by reducing the cost.   Another approach to lower chemical costs is to provide the chemicals in bulk or semi-bulk containers. In this way, the costs for drums and drum disposal are eliminated

Sustainable fibers

Natural fibers are subdivided into two classifications: animal (protein) and plant (cellulose) fibers. Protein fibers include wool, cashmere, alpaca and silk.  Cellulose fibers are produced by plants, and are products of agriculture. Fibers are either bast fibers (the fiber surrounding the stem of the plant such as flax or hemp), or seed fibers such as cotton. Regenerated fibers also known as man‐made fibers are created artificially by using the building blocks provided by nature (e.g. proteins or cellulose). A regenerated fiber would typically be a natural material that has been converted by wet‐chemical processing that allows the production  of continuous  filaments that can then be spun into fiber (e.g. viscose).

Environmental concerns

Textile processing is a water intensive sector.  On average, an estimated 200 liters of water is needed to process 1kg of textile material. The development of ionic liquids that exhibit useful and unique properties can create huge untapped potential for commercial applications to increase operating efficiencies of many chemical production operation – including the processing of textiles.

The main environmental concern in the textile industry is all about the amount of water discharged and the chemical load it carries. Air emissions are usually collected at their point of origin, because they have long been controlled and there are good historical data on air emissions from specific processes. This is not the case with emissions to water. The various streams coming from the different processes are mixed together to produce a final effluent whose characteristics are the result of a complex combination of factors such as, the types of fibers and make-ups processed, the techniques applied and the types of chemicals and auxiliaries used. Chemicals give textiles color and performance that a consumer demands. Chemicals are not bad, but it depends on how they are used. A safe chemical used wrongly can be many times polluting than a classified chemical used correctly. Both natural and man-made fibers contain impurities such as metals, lubricants, and other residues that contribute to pollution in mill effluent. Chemical releases from the textile processing sector is not well quantified. Data on releases, particularly air emissions, are not readily available. Most estimates are based on mass-balance calculations rather than direct measurement. The industry is coming together to develop ways to identify and quantify releases.

Best available techniques is the most effective and advanced stage in the development of activities and their methods of operation which indicate the practical suitability of a  particular technique for providing in principle the basis of emission limit values. Techniques include both the technology used and the way in which the installation is designed, maintained and operated. Thus, Best technology means in achieving a high general level of environmental protection of the environment as a whole.  Information on Best Available Technology (BAT) can thus support textile processing, policy makers and the regulators in addressing environmental concerns with the application of abatement strategy, thereby limiting pollutant discharges and improving the environment.

Clean and emerging technologies

The term “clean technologies” is defined as “manufacturing processes or product technologies that reduce pollution or waste, energy use, or material use in comparison to the technologies that they replace. Some of the clean technologies include:

  • Pad-batch dyeing
  • Low bath ratio dyeing
  • Low salt/high fixation dyeing / Salt free dyeing
  • Dye bath reuse
  • Continuous dyeing for knits
  • Automated color mix kitchen
  • Automated chemical dosing
  • Digital printing / Transfer printing
  • Laser engraving of printing screens
  • Surfactant substitution
  • Recovery of synthetic sizes
  • Countercurrent washing
  • Low add-on finishing {Foam finishing}

Conclusion

The tools available to a researcher today are plenty and technological positioning of ideas from other streams of sciences converts a modern day scientist into a virtual magician, especially when it comes to polymers, fiber forming long chain molecules for textiles.

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