Combustion behavior, mechanical performance and application for vinyl acetate–ethylene copolymer emulsion containing melamine amino trimethyl phosphate and sodium lignosulfonate

An intumescent-flame-retardant vinyl acetate–ethylene copolymer (IFR/VAE) compound has been prepared by blending with a complex of melamine amino trimethyl phosphate (M-AT) and sodium lignosulfonate (SL). Then, this obtained IFR/VAE polymer was applied as adhesives for producing the flame-retardant plywood. The IFR VAE sample (VAE/M-AT3/SL1) with a mass ratio 3:1 (M-AT to SL) showed an enhanced amount of char residue, limiting oxygen index (LOI) value and tensile strength value to 20.6 wt%, 32 vol% and 19.3 MPa, which have been increased by 796%, 600%, and 56% compared to that of neat VAE. The cone calorimeter result showed that the peak of heat release rate (pHRR) of VAE/M-AT3/SL1 sample was reduced by 48% compared to the control one. Additionally, the second peak of HRR of sample IFRPW/15 L/15 (containing 15 wt% M-AT3/SL1 in the plywood adhesive layer) presented a reduction of 29% compared to that of the sample PW/15 L (neat plywood). It is assigned to the formation of phospho-carbonaceous structure during combustion, thus the flame-retardancy of plywood has been greatly enhanced. Thus, this work provides an economical and applicable fire-retardant VAE adhesive formula for producing plywood materials with good performances.