Thermal insulation materials are generally lightweight, loose, porous and fibrous materials. According to its composition, it can be divided into organic materials and inorganic materials. The former has better thermal insulation performance than the latter, but the latter has better durability than the former. Thermal conductivity is the main indicator to measure the performance of thermal insulation materials. The smaller the thermal conductivity, the smaller the heat transferred through the material, and the better the thermal insulation performance. The thermal conductivity of the material is determined by the composition, internal structure, bulk density, etc. of the material, and also determines the average temperature during heat transfer and the water content of the material. rate. Generally speaking, the lighter the bulk density, the smaller the thermal conductivity