Synthesis and characterization of water borne intumescent fire retardant varnish based on phosphate resin acid cold cured amino resin

In this research, a water borne intumescent fire retardant varnish based on phosphate resin acid (PRA) cold cured amino resin was synthesized. Infrared (IR) spectrum proved that PRA was from 1,4-butanediol diglycidyl ether (BDE) and epoxy resin E-51 (E-51) via the reaction between epoxy group and POH of phosphate ester acid of N-butyl alcohol (BA) and pentaerythritol (PT). The introduction of BDE and E-51 improved water resistance and flexibility of painted film. The fire retardancy test demonstrated that a higher phosphorus content is beneficial to the intrinsic fire retardancy of painted films, but the high quality char formation is another key of fire retardancy of painted films. The TG and DTA proved: E-51 and PT are true carbon source that is beneficial to form a high quality charred layer, but their high combustion heat is detrimental to the intrinsic fire retardancy of painted film material. BDE is beneficial to increase the intrinsic fire retardancy of painted film material, but detrimental to form a high quality charred layer. The conclusion also is showed directly by the scanning emission microscopy (SEM). To achieve high performance painted film, all the components need to be balanced perfectly.

► Water borne intumescent fire retardant varnish based on phosphate resin acid (PRA) cold cured amino resin was synthesized.
► Phosphate resin acid was made from epoxy resin via the reaction between epoxy group and POH of phosphate ester acid.
► The introduction of BDE and E-51 improved water resistance and flexibility of painted film.
► The effect of phosphorus content, pentaerythritol, E-51, 1,4-butanediol diglycidyl ether on fire retardancy of painted films was studied.