1a. Objectives (from AD-416)
Objective 1: Enhance and promote cotton’s natural sustainability features in the context of disposable nonwovens applications. Objective 2: Characterize and correlate the relationships among the cotton fiber quality parameters, the nonwovens process-ability, and the final fabric performance characteristics. Objective 3: Develop and optimize hydro-entanglement chemistry and process parameters for cotton fiber and the nonwoven fabrics thus produced. Objective 4: Develop innovative end-use functional technologies that enable increases in the amount and value of cotton used in nonwoven applications. Objective 5: Develop processes for producing nonwoven fabrics from greige cotton.
1b. Approach (from AD-416)
The ultimate goal of this research project is to increase value-added utilization of cotton via development of performance-specific nonwoven products containing cotton. The term "cotton" used here includes cotton lint, ginning motes and linters, comber noils, processing wastes, recycled cotton, and the like. The research approaches broadly involve 1) characterization of fibers and fiber blends to be used; 2) selection of optimum processes and conditions for fiber opening, cleaning, and web formation; 3) selection of appropriate nonwovens production system; 4) evaluation of process and product performances; 5) physical, mechanical and/or chemical modifications of nonwoven products to attain and/or enhance the required functionality; 6) within the scope of the project, determine biodegradability, cost-effectiveness, environmental impact and sustainability of the products produced; and 7) disseminate the research results via publications, technical forums, and technology transfer to industry. Specifically, the research involves developing fiber-processing technology to obtain supply of clean greige/virgin (scour/bleach-less) cotton that is appropriate for the intended end-use application. Most of the existing manufacturers of nonwoven rollgoods do not have the resources, facilities and/or technical expertise to open and clean supply bales of greige cotton(s). It is imperative to develop a protocol that would enable the nonwovens manufacturers to either both open and clean cotton in their in-house facilities or obtain some readily available pre-cleaned cotton. Depending on individual products, we will determine efficient routes for processing cotton into a clean web for downstream processes. SRRC has the equipment, including cotton carding, to thoroughly open and clean virgin cotton and also the resources to procure and process pre-cleaned supply cottons (say, UltrcleanTM cotton). The preferred research focus is on using greige cotton, instead of bleached cotton that currently is primarily used in premium quality nonwovens. However, nonwoven fabrics made with cleaned greige cotton may be satisfactorily scoured and bleached, if necessary. To determine which cotton would be most cost effective for certain specific end-use applications, certain experimental investigations and small-scale industry-like production trials have been planned. They involve studies of the fiber, process and product metrics and their relationships. Research efforts will be redirected to improve any marginal outcomes. In general, carding process will be deployed to form a web for the downstream needle-punching and/or hydroentangling systems of producing nonwoven products. Optimizations of the N-P and H-E processes and products will be sought through planned investigations. Comprehensive testing of in-process products and end-products will be conducted to realistically evaluate the research outcomes. Statistical tools will be used for reliability of the results. Issues concerning the biodegradability, disposability, environmental impact, safety, government/industry-compliance,and cost-analysis will only be conducted to the extent feasible within the scope of the project.
3. Progress Report
This is the first-year report of a new in-house research project that involves a comprehensive nonwoven research program and a massive installation of new equipment. Significant progress has been made in successfully attaining almost all of the planned objectives and goals. All of the new equipment is now fully operational and productive. Numerous experimental studies and trials to optimize the machinery parameters for producing cotton nonwoven fabrics have been conducted. These studies and trials have demonstrated that pre-cleaned raw/greige (non-bleached) cotton indeed can be used for producing nonwoven substrates for many end-use applications, such as wipes, fleece, sheets, etc. The research products are currently being evaluated commercially. Studies conducted to determine the comparative biodegradability (for the life-end disposal) of cotton-based and manufactured-fiber-based nonwoven fabrics have shown that the cotton-based fabrics biodegrade much faster than the others and that their exposure to soil may be a better bet than a landfill for efficient disposal, which may encourage the replacement of synthetic fibers with cotton in certain disposable products. In another study, certain discounted cotton products, such as cotton ginning and processing wastes, were processed at Clemson University and converted into hydroentangled nonwoven fabrics at the Southern Regional Research Center (SRRC) in New Orleans, Louisiana. The preliminary results indicate that these cotton byproducts may also be beneficially utilized in nonwoven products. In another study to improve flame resistance of cotton nonwovens, the function of a less expensive urea additive, compared to the commonly used, three times more expensive diammonium phosphate fire-retardant (FR), was elucidated. The results have been satisfactory. The extensive research efforts devoted to producing mostly greige cotton-based nonwoven substrates have led to the possibility of eliminating the traditional scouring process. This may lead to even more efficient bleaching, possibly by reducing “burden” of the process. Separately, under a CRADA with a U.S. Cotton Producer and Ginner, an experimental study was conducted to determine the effect of fiber properties of pre-cleaned (UltraCleanR) cotton on the nonwovens process and product. The study has demonstrated that, unlike the traditional woven textiles, the fiber properties, within the normal ranges investigated, did not significantly affect properties of the fabrics produced. In addition, the laundering of these hydroentangled cotton fabrics has revealed, for the first time ever, that the fabrics can be repeatedly machine washed and dried for up to 20 cycles, while still retaining most (~80%) of their original mechanical integrity and dimensional stability. In another comprehensive study of application of “quats” or other chemistry to cotton to improve the latter’s ”adherence” and “release” attributes of the anti-microbial agents, a new fundamental information has been obtained in that the greige cotton-based nonwoven fabrics adsorb and retain significantly more quat than similar fabrics that have been scoured and bleached.
1. Utilization of raw/greige cotton in nonwoven products. Although nonwoven fabrics are growing rapidly, the use of cotton in these fabrics has been minimal. This is partly because the raw cotton requires substantial cleaning of its non-cotton contaminants, for which the existing nonwoven rolls manufacturing entities are not equipped since they mostly process synthetic/manufactured fibers that inherently are almost 100% pure, clean and white. In order to explore the feasibility of processing greige cotton for use in nonwovens, the ARS scientists at the Southern Regional Research Center (SRRC) in New Orleans, Louisiana, devoted extensive research efforts to find practical ways to produce viable nonwoven fabrics using raw cotton as well as pre-cleaned raw cotton. The research has demonstrated that raw/greige (non-bleached) indeed can be efficiently converted into viable nonwoven substrates.
2. Elimination of the traditional chemical scouring process for hydroentangled greige cotton nonwoven fabrics. Raw cotton fibers always have some amount of high molecular-weight hydrocarbons (waxes, pectins, etc.) in the form of a sort of protective membrane. These waxes are water repellent and thus do not permit the cotton fiber to absorb water. Since absorbency of most textile materials for apparel and other similar applications is critical for chemical modifications, wear comfort, washing, etc., it is imperative that these waxes are completely removed at the first opportunity. Therefore, almost all cotton textiles are scoured and generally bleached to attain the desired absorbency. ARS researchers at the Southern Regional Research Center (SRRC) in New Orleans, LA, have discovered that hydroentangled raw cotton nonwoven fabrics, produced with certain specific operating conditions, can be made absorbent without the traditional scouring process which is costly, cumbersome and environmentally sensitive.
3. Development of certain novel nonwoven products containing greige cotton. Applied research conducted at the Southern Regional Research Center's (SRRC’s) in New Orleans, LA, Cotton-Based Nonwovens research program has led to the development of some unique, potentially high-volume, value-added products containing cotton. The two promising products that currently are being evaluated by commercial entities are: 1) 100% cotton and 80:20 cotton:polyester-film composites for quilts, blankets and other similar handicrafts; and 2) an environment-friendly kitchen (100% cotton) wipe that has a naturally growing plant dye/pigment that is naturally antimicrobial and needs minimal (candle) light to activate its antimicrobial feature for up to 20 repeated washes. Incidentally, both products are readily biodegradable and are in or near the market, as well.
4. Discovery of new knowledge. Industry is seeking antimicrobial wipes that can efficiently perform in the meat/food plants. The existing products mostly containing manufactured fibers, especially polyester, fall short of the industrial expectation, mainly because of the less-than-satisfactory absorption, retention and dispensing (delivery) of the antimicrobial ingredient(s). Although cotton fiber, compared to polyester, has much greater absorbency, it also poses certain difficulties of its own, especially in the more retention and less dispensing of the chemical agents. Research done at the Southern Regional Research Center (SRRC) has revealed new knowledge that is expected to promote use of greige cotton for producing nonwovens for the wiping and other end-use applications.
Sawhney, A.P., Reynolds, M.L., Condon, B.D., Slopek, R.P., Hui, D. 2010. An Efficient process for producing economical and eco-friendly cotton textile composites for mobile industry. World Journal of Engineering. 7(1):150-153.