Recent papers show innovative solutions for PIN fire safety treatment of cotton fibres, using layer-by-layer deposition of PIN flame retardant combinations including bio-based chitosan, phosphorylated poly vinyl alcohol (PVA), PHMGM (polyhexamethylene guanidine phosphate) and melamine polyphosphate (MPP) and ammonium phosphate (APP).
Chitosan is a widely occurring natural nitrogen-containing polysaccharide (present e.g. in shellfish and crab wastes). PVA is a very biodegradable, water soluble polymer. These two chemicals were deposited onto cotton fabric using a water-based process. 30 bi-layers resulted in significantly improved fire performance (reduced peak heat release, lower volatile organic gas emissions, self-extinguishing). PHMGP and APP were deposited onto cotton fibres in multi-layers, also using an aqueous process (1 minute dipping, 30 seconds rinsing, drying for each layer). 20 bi-layers significantly reduced cotton flammability (but self-extinguishing was not achieved) and also offered anti-microbial properties. Multilayer chitosan and melamine polyphosphate on polyester-cotton fabric was achieved in a water-based process by generating the (water-insoluble) MPP on the fibre surface by reacting aqueous solutions of melamine and sodium hexametaphosphate. 15 bi-layers of chitosan and MPP achieved self-extinguishing on polyester-cotton fabric.
“An eco-friendly way to improve flame retardancy of cotton fabrics: layer-by-layer assembly of semi-biobased substance”, H. Pan et al., Energy Procedia 75 (2015) 174 – 179 http://dx.doi.org/10.1016/j.egypro.2015.07.631
“Construction of intumescent flame retardant and antimicrobial coating on cotton fabric via layer-by-layer assembly technology”, F. Fang et al., Surface & Coatings Technology 276 (2015) 726–734 http://dx.doi.org/10.1016/j.surfcoat.2015.05.023
“Water-based chitosan/melamine polyphosphate multilayer nanocoating that extinguishes fire on polyester-cotton fabric”, M. Leistner et al., Carbohydrate Polymers 130 (2015) 227–232 http://dx.doi.org/10.1016/j.carbpol.2015.05.005