Halogen-free flame retardant (FR) polyamide 6 (PA6) textile filaments
A novel scalable approach for the production of a halogen-free flame retardant (FR) polyamide 6 (PA6) textile filaments with self-extinguishing properties have been developed.
The developed approach includes incorporation of the homogeneously distributed nanodispersed organophosphorus FR molecules in the PA6 matrix and subsequent melt-spinning of the textile filament yarns. Incorporation of FR molecules during the polymerization process is a cost-effective approach which eliminates an additional melt-compounding step.
Depending on the chemical structure, the organophosphorus molecule can be incorporated in the PA6 matrix as chemically linked to the backbone of the PA6 polymer or physically incorporated in the PA6 nanocomposite. The added values of these new FR PA6 materials is maximal preservation of the mechanical properties of the polymer and their stability during the melt-processing, which enable highly valuable continuous performing of the melt-spinning process without clogging of the filters and spinnerets.
The nanodispersed organophosphorus FR molecule in the PA6 nanocomposite provided self-extinguishment of the fibre strand and knitted fabric samples at FR concentration of 15 wt. % within 1 s in standard vertical flame spread tests (ASTM D6413), followed by the complete reduction of the melt-drop flammability, whilst the melt-dripping was significantly reduced.
The 1.2 mm-tick bar samples achieved V0 rating in the UL94 vertical burning testing at FR concentration of 10 wt. %, which confirmed the highly effective flame retardant action of the incorporated nanodispersed FR additive.