|De Lucca, Anthony - Retired ARS Employee|
|O'regan, Janet - Cotton, Inc|
|Clemmons, Julie - Cotton, Inc|
|Allen Jr, Hiram|
|Santiago Cintron, Michael|
Submitted to: Textile Research Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/22/2013
Publication Date: 3/12/2014
Citation: Hinchliffe, D.J., De Lucca, A., Condon, B.D., O'Regan, J., Clemmons, J., Zeng, L., Byler, R.K., Reynolds, M.L., Allen Jr, H.C., Santiago Cintron, M., Madison, C.A. 2014. A pilot-scale nonwoven roll goods manufacturing process reduces microbial burden to pharmacopeia acceptance levels for nonsterile hygiene applications. Textile Research Journal. 84(5):546-558.
Interpretive Summary: The use of cotton fibers in certain nonwoven hygiene products requires compliance with established guidelines for limits on microbial contamination. The level of microbial contamination, commonly referred to as microbial burden, is further divided into total microbial counts and yeasts/molds counts that are distinguished by growth on specialized nutrient sources. Currently, the microbial burden of natural fibers such as cotton have not been quantified and little consideration has been given to the potential contamination introduced by synthetic fibers during the processing from synthesis to nonwoven fabrics production. Also, the possibility of cross-contamination when running cotton fibers and synthetic fibers on the same line has not been investigated. The objective of this study was to measure the microbial burden on cotton and synthetic fibers, the nonwoven fabrics, and the waste water produced from the hydroentanglement process. The microbial burdens of the cotton and synthetic fibers and nonwoven fabrics were determined by examining effluents collected at various stages of processing. The results suggested the hydroentanglement process used in a pilot scale facility was sufficient to remove the microbial burden to levels that meet Pharmacopeia acceptance criteria for utilization of greige cotton fibers in nonsterile personal hygiene products.
Technical Abstract: A total of seven source fiber types were selected for use in the manufacturing of nonwoven roll goods: polyester; polypropylene; rayon; greige cotton from two sources; mechanically cleaned greige cotton; and scoured and bleached cotton. The microbial burden of each source fiber was measured as a preliminary assessment of microbial contamination using heterotrophic pour plate counts. Greige cotton fibers exhibited the highest levels of total microbial contamination, which were reduced by both storage time and trash removal in the form of mechanical cleaning. Changes in microbial burden levels were measured at each step in the nonwoven manufacturing process that included opening, carding, needlepunch fabric production; hydroentangled fabric production and recovered effluents, and final hydroentangled roll goods. The hydroentanglement process resulted in the greatest overall reduction in microbial burden with no detectable levels of aerobic microbial contamination present on any of the final hydroentangled roll goods regardless of the source fiber. No detectable levels of aerobic microbial regrowth were observed on any fabrics despite storage time or ambient storage conditions. Analysis of suspended solids present in hydroentanglement effluents collected during fabric production revealed significantly less suspended solids from synthetic fibers compared to all cotton fiber types. Among the cotton fibers utilized, greige and greige mechanically cleaned released significantly less suspended solids than scoured and bleached. The study provided insight and potential guidelines that could be incorporated into a nonwoven processing line to ensure specific sterility requirements are met for various converters in end-uses such as hygiene and medical applications.