Washington, D.C, United States - Nylon-spandex fabrics have been ubiquitous in several end-uses, and while they have some challenges for the dyer in achieving fastness, they have performed well in the market place.Until recently, polyester spandex fabrics have been less common, mainly because the high temperatures required for dyeing the polyester could damage the spandex. Improved spandex, and the significantly lower cost of polyester have resulted in the proliferation of the use of polyester stretch fabrics (i.e. fabrics incorporating polyester, and spandex type yarns) in (new) apparel and home furnishing applications. This has resulted in a new, and unique issue, particularly associated with such fabrics dyed to dark shades (black, navy, burgundy, forest green, etc.). These shades are achieved with disperse dyes that dye the polyester satisfactorily, but which also color the spandex component*. Any residual dye on the polyester surface is cleared by a standard reduction clearing treatment. The dye on the spandex is not readily cleared by this treatment, and its staining propensity (in storage and/or consumer use) is not readily revealed by standard colorfastness tests (such as crocking, laundering, water, perspiration, or dye transfer in storage), traditionally used by the trade for “acceptance testing”. However, during storage and/or consumer use, when exposed to conditions that are conducive to the movement of disperse dyes, dyes from the spandex can migrate onto adjacent materials that are receptive to disperse dyes (such as polyester labels, paper, or plastic), and result in noticeable and objectionable staining of the materials.
Based on projects conducted in his practice of providing independent technical services to the trade, Adi Chehna, President of Textile Tech Services (and Chair of AATCC RA 99, Technical Manual Editorial Review) presented information (and samples) demonstrating this situation to AATCC’s Technical Committees on Colorfastness [viz. RA 23-Water, RA 38-Crocking, and RA 60-Washing], as well as to RA 59, Fibrous Test Materials, RA 75, Evaluation of Materials and Products for End Use Performance, and the Technical Committee on Research (TCR). During discussions in these Committees, other US as well as International AATCC members confirmed the experiences reported by Chehna. In response, starting in 2014, AATCC has added a Note of Caution to its colorfastness methods, advising users of this situation. In the meantime, Chehna, and Martin J. Bide (of the Department of Textiles, Fashion Merchandising and Design, at the University of Rhode Island), have been working on developing possible test protocols that could be used to identify the staining propensity of polyester/spandex type fabrics during storage, and/or consumer use. In order to study the viability of these test protocols, and to consider their adoption as standard test methods, AATCC will hold an exploratory meeting at its upcoming (November 2013) Technical Committee meetings, to re-activate Committee RR 92, Interaction of Dyes and Finishes, currently in Reference status. This meeting will be held on Tuesday, November 12, 2013, from 1:00 pm until 1:45 pm, with Bide acting as temporary chair. All interested parties are invited to attend.
*(The extent to which the dye partitions between the two fibers, the effects of reduction clearing, and the resulting wet fastness has been the subject of Suwanruji et al., “Study of the removal of a disperse dye stain from a polyester/elastane blend,” Coloration Technnology 128 (#2 2012) p103. The phenomenon seems to be dye-dependent.)
Source: American Association of Textile Chemists & Colorists (AATCC)