Massive volumes of native starch and modified starch is consumed by textile yarn sizing units all over the world; specifically for cotton/PC yarn sizing. While the starch suppliers can boast about supplying bio-degradable materials; are they really safe for the environment? And, if not starch then what could be safer?
There has been a lot of development and progress in yarn construction to have inherit high strength and elasticity; but sizing is still a necessity for the yarns to cope up with increasing speeds and hi-tech weaving machines. As the sizing chemicals are washed off to the environment after weaving (desizing), biodegradability, toxicity and cost of treating the waste effluent may become a concern for sustainability. Along with natural polymers like starch, considerable amounts of synthetic polymers like PVA, polyesters, and polyacrylates are being used for sizing. A long list of other additives such as softeners, defoamers, lubricants, humectants, wetting agents, and anti-static agents may further add to concerns in de-sized effluent.
Starch and its derivatives are undoubtedly sourced from renewable materials. Hence, environmental safety is not questionable in terms of its actual use but the problem is the effluent created in its chemical treatment during desizing. Such issues have been extensively addressed by use of enzymes, but easy washing ability is a need of the hour.
PVA, a frontrunner, as sizing binder for many years are now being demanded to be replaced by the Textile industry. With very high COD values of PVA, issues in treating waste effluent surpasses the benefits of using it. PVA blocks the RO membrane of effluent treatment plant requiring RO columns to be replaced in regular intervals. Advent of biodegradable polyesters and good polyacrylates with starch and its derivates is reducing the popularity of PVA in textile sizing. Attempts in recycling and reuse of PVA from the desized solution has failed to be economically viable. Because of certain properties of PVA like versatility, reproducibility and compatibility with other sizing ingredients and type of yarn; it still remains a popular choice among the sizers.
Sustainability is need of the hour for our planet; and it can be achieved when you break paradigm by small improvements or breakthrough products. In the sizing world, this shift in paradigm could be brought by exploring few of the following:
- Grafted starch: Grafting of starch with monomers is being extensively researched since few years but has been a challenge to manufacture on the commercial scale. Reproducibility and control over homo- and cross polymerization and later separation of the respective products add up to the cost of production and hampers commercial viability. Although, grafted starch could be a breakthrough solution for many industries including Textiles, a lot of research is yet to succeed in producing a commercial product with robust consistency.
- Modified starch: Numerous modified starches are developed and known for ages. And, they are being used in textile sizing. Hence, Starch & derivatives form a predominant component in almost all sizing products for cotton and PC yarn. Modified starch having easy washing ability without use of chemicals and enzymes for desizing will prove to be a more sustainable option. Hydrophobic modified starches with softening and wetting ability can further eliminate need of external softeners and wetting agents.
- Cold water soluble sizing product: A vast majority of sizing companies cook sizing material at 90-130°C for upto 30 minutes before use. A cold water soluble sizing product that does not require cooking will help in saving cost and energy required for heating process. This would need a big change in mindset bringing a paradigm shift. Current high price and lower performance of cold water soluble starches that are available in the market is limiting its use or replace existing products.
- Use of expensive but high performance sizing products at lower pick-up could be another solution. Use of synthetic polymers at lower pick-ups are very well known and practiced in the market, but use of starch & its derivatives at such low pick-ups are less familiar.
Starch is abundantly available in nature and obtained from many sources like Potato, Corn, Tapioca, wheat, peas, etc. Being a natural polymer, it can primarily be the first stop to develop sustainable products to substitute synthetic chemicals and polymers. Focused research in modifications of the starch to achieve the desired properties could be the key to sustainable textile sizing.
We at Karandikars Orgochem Pvt. Ltd. are addressing above issues with continuous R&D and commitment towards sustainable future.
Karandikars Orgochem Pvt. Ltd. (formerly Karandikars Cashell Pvt. Ltd.)
Dr. Satyajit Karandikar
CEO & Director
+91-8169239822 / 9821150621
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