Study on the flame retardant property of reactive halogen-free organic grouting reinforcement materials for coal mines

The high content of halogen in common polyurethane grouting reinforcement material (PU) results in catalyst poisoning and deactivation in coal chemical enterprises. To solve this problem, a kind of reactive halogen-free organic grouting reinforcement material(PU-NH) was prepared. Its flame retardant property was investigated by limiting oxygen index(LOI). The thermal stability and combustion performance of PU-NH were investigated by Thermogravimetric differential scanning calorimetry (TG-DSC) and cone calorimetry. The results show that PU-NH is kind of refeactory material and compared with PU, PU-NH has better thermal stability, and the smoke emission and CO emission of PU-NH are reduced by 39.3% and 50.75% respectively. Scanning electron microscope(SEM) and X-ray photoelectron specteometer(XPS) characterization of carbon residue after material combustion results show that, the carbon residue of PU-NH has a honeycomb structure after combustion. It can form a fluffy and complete carbon layer on the surface of the material during combustion, effectively isolating the oxygen and slowing down the rate of heat conduction. It is the fundamental reason for the good flame retardant performance of the material. At the same time, the high carbon element in PU-NH carbon residue is also conducive to the formation of carbon layer and improve the oxidation resistance. The underground grouting test of coal mine shows that the performance of PU-NH is higher than the industry standard of polymer material used for coal rock reinforcement, which can effectively improve the bearing capacity of coal rock mass and guarantee the life safety of workers after reinforcement.