Study on low calorific value and foaming property of phenolic resin modified by compound catalyst

Traditional phenolic resin will release a large amount of reaction heat in the process of coal mine filling and plugging, which is easy to cause the temperature rise in the filled coal seam area, resulting in the problem of coal spontaneous combustion. In view of this technical problem, the key component of phenolic resin synthesis “basic catalyst” was improved in this paper, “Basic catalyst A” was prepared. The effects of catalyst A and other basic catalysts on resin viscosity, solid content, foam curing temperature, foam ratio and microscopic pore structure were compared and analyzed. The curing exothermic mechanism of modified phenolic resin (N-PF) synthesized from catalyst A was explored. The results show that N-PF resin has higher foaming rate, better viscosity and lower curing temperature. The micropore size data showed that the application of alkaline catalyst A increased the pore size of N-PF resin foam, and the foam powder rate was lower than that of PF foam, with better mechanical properties. FT-IR and 13C-NMR data showed that the hydroxymethyl index of N-PF was lower than that of PF, which was beneficial to the reduction of total heat release during the curing process of phenolic resin. Differential scanning calorimetry (DSC) analysis and theoretical calculation show that the heat release of N-PF during curing process is more gentle than that of PF, avoiding the rapid heat accumulation. At the same time, it was found that the temperature of the cured body and the ambient temperature of the foaming body of N-PF under the same curing system were significantly reduced, the temperature of the cured body decreased by 46% from 125 ℃ to 65 ℃, and the ambient temperature of the foaming body decreased by 21% from 41.8 ℃ to 32.9 ℃.