A novel UV-curing flame retardant film with significantly intumescent effect

High flammability has always been a major challenge hindering in application of most conventional UV-curable resins. Herein, several intumescent flame-retardant (FR) films characterized with crosslinked network structure were successfully prepared via the combination of tri(acryloyloxyethyl) phosphate (TAEP) with melamine-based acrylate resin (MAAR) by UV-cured method. As compared with sole TAEP- or MAAR-containing films, the mixed films containing TAEP and MAAR exhibited improved flame retardant property. The characterizations of their flammability and char morphologies indicated that the PN-2 with 2/1 mass ratio of TAEP to MAAR had the relatively better flame retardance and could form the intumescent char layer with many thin-walled large bubbles under the compact surface layer. Furthermore, the evolved products for PN-2 with 2/1 mass ratio of TAEP to MAAR during the thermal degradation exhibited much less release than neat TAEP- or MAAR-containing coatings, which implied the increase of the pyrolysis products inside the char layer and thus leaded to the expansion of the intumescent FR films. These results suggest the UV-curing intumescent FR films containing TAEP and MAAR with appropriate ratio possess great flame retardant efficiency that in favor of further application on a substrate, such as fabrics, wood, and plastics.