Abstract:

A flame retardant containing phosphorus， silicon and boron in its molecular structure （SiBP） was synthesized using 9，10⁃dihydro⁃9⁃oxa⁃10⁃phosphine⁃10⁃oxide， dimethoxymethyl vinyl siloxane， and boric acid as raw materials， and its chemical structure was characterized using Fourier⁃transform infrared spectroscopy and hydrogen nuclear magnetic resonance spectroscopy （¹H⁃NMR）. The thermal stability of SiBP was also characterized by thermogravimetry （TG）. The SiBP exhibited an initial decomposition temperature of 110 ℃ in nitrogen atmosphere was， resulting in a residual char yield of up to 40 wt% at 800 ℃. A flame⁃retardant coating was prepared by using silicone acrylic lotion as a matrix， silicon powders as an inorganic filler， SiBP as a main flame retardant， and ammonium polyphosphate （APP） as a synergistic flame retardant together with dipentaerythritol （Di⁃PE） and melamine （MEL）. The fire⁃resistant performance was characterized and analyzed through limiting oxygen index （LOI）， UL 94 vertical combustion test， TG， and large board combustion test. The micro and macro morphologies of the char layer after combustion were observed using scanning electron microscope. The strength of char layer and the peel strength of coating were characterized using compression tester and electronic universal testing machine. The results indicated that when the addition amounts of APP， SiBP， Di⁃PE， MEL， and silicon powders were 10， 20， 8， and 25 phr， respectively， the flame⁃retardant coating achieved an LOI of 29.2 % along with a UL 94 V⁃0 classification and a carbon residue rate of 38.5 wt%， and its peel strength increased to 0.325 kN/m. In addition， the compressive strength of the char layer increased to 1.4 MPa along with an increase in hydrophilicity.

Key words: silicone acrylic lotion, synthesis, flame retardant, fire retardant coating