Flame behavior of cotton coated with polyurethane containing microencapsulated flame retardant agent

Polyurethane-phosphates combination is known to form flame retardant (FR) intumescent system. But the intumescent formulation could not be permanent because of the water solubility of the phosphate. This problem could be solved by the technique of microencapsulation. Microcapsules of di-ammonium hydrogen phosphate (DAHP) with a polyurethane (PU) shell were synthesized. Chemical and physical structure of the DAHP microcapsules were characterized. Cotton fabrics were coated with polyurethane (PU) coating including neat DAHP or encapsulated DAHP. The flame retarding behavior of these coated cotton fabrics was valued with the cone calorimeter. This new concept of phosphate encapsulated by PU shell showed a significant FR effect.