膨胀蛭石在防火涂料中的阻燃和抑烟作用

Effect of expanded vermiculite on flame retardancy and smoke suppression of fire retardant coating

以硅丙乳液为成膜物质,聚磷酸铵、季戊四醇和三聚氰胺为膨胀阻燃体系,添加不同量的膨胀蛭石作为协效阻燃抑烟剂,制备水性膨胀型防火涂料。采用小室燃烧法、隧道燃烧法、大板燃烧法、烟密度测试法、热重分析和差热分析研究膨胀蛭石对防火涂料的阻燃和抑烟作用。结果表明:膨胀蛭石的加入有效提高了防火涂料的阻燃性能和抑烟性能。添加5%的膨胀蛭石时,试样的质量损失、炭化体积和火焰传播比值分别下降了17.18%、49.33%和32.81%,烟密度等级从16.80%降至6.74%。热重分析和差热分析表明,膨胀蛭石的阻燃和抑烟作用主要为提高防火涂料的最终残炭量和炭层的稳定性,减少气相挥发物的生成和热量的传递。添加5%的膨胀蛭石便可使试样的残炭量增加10.64%,炭层初始分解温度从505.4℃提高到547.3℃。

The water-based intumescent fire-retardant coating was prepared using silicone acrylic emulsion as binder, ammonium polyphosphate,pentaerythritol and melamine as flame retardant system, different amounts of expanded vermiculite as synergistic flame retardant and smoke suppressant. The flame retarding and smoke suppressing properties were analyzed by cabinet method, tunnel method, big panel method, smoke density test,thermo-gravimetric analysis （TGA） and differential scanning calorimetry （DSC）. The results showed that the addition of expanded vermiculite could enhance the flame retardancy and smoke suppression performance of the intumescent fire-retardant coating significantly. When mass fraction of expanded ver- miculite was 5%, the mass loss, volume of carbonization and flame spread ration decreased by 17.18% ,49.33% and 32.81% respectively, and the smoke density rating decreased from 16.80% to 6.74%. TGA and DSC indicated that expanded vermiculite could improve the final amount and thermal stability of residual carbon of intumescent fire retardant coating,and reduce the produce of gaseous volatiles and the transmission of heat, which was believed to be the main contribution to the improvement of both flame retardancy and smoke suppression performance. The final amount of residual carbon increased by 10.64%, and the initial decomposition temperature increased from 505.4 ℃ to 547.3℃ at presence of 5% expanded vermiculite.