New Development in Flame Retardant Finishing of Cotton Blend Fabrics

Blending cotton with synthetic fibers drastically improved durability for use in protective clothing. Developing new flame retardant finishing technology for cotton blends was critical for producing low cost, durable and high performance fire resistance military protective clothing. In this paper, we discussed the flame retardant finishing of the Nomex/cotton (65/35) blend fabric using a hydroxy-functional organophosphorus oligomer (HFPO) in combination with 1,2,3,4-butane-tetracarboxylic acid (BTCA) as a bonding agent and triethanolamine (TEA) as a reactive co-additive. Because cotton was a highly flammable fiber, the Nomex/cotton blend fabric containing more than 20% cotton required flame-retardant finishing treatment. BTCA reacted with HFPO, cotton and TEA to form BTCA/HFPO/TEA/cotton crosslinked polymeric network, which improved the hydrolysis resistance of HFPO, whereas TEA provided synergistic nitrogen to enhance the performance of HFPO. The Nomex/cotton blend treated with the HFPO/BTCA/TEA system shows high flame retardant performance and excellent laundering durability at relatively low add-on levels. We also discussed the flame retardant finishing of the 50/50 nylon/cotton blend military fabrics using the combination of HFPO and dimethyloldihydroxyethyleneurea (DMDHEU), which formed HFPO/DMDHEU crosslinked networks on both cotton and nylon in the blends. The treated blend fabric passed the vertical burning test after 40-50 launderings cycles with negligible fabric strength loss. The heat release rate data indicated that the nylon and cotton fibers interacted with each other during their thermal decomposition on the blend fabric treated with the HFPO/DMDHEU system.