The thermal conductivity of ordinary plastic products is mostly in the range of 0.15 ~ 0.22W / (m, K), while the thermal conductivity of foam plastics is generally in the range of 0.01 ~ 0.04W / (mK), 15 ~ lower than ordinary plastic products It is 50 times as much as it has excellent thermal insulation properties and is often used as a heat insulating material. The resins commonly used as insulating foam products are hard PU, PF, urea-formaldehyde and PS. The thermal insulation properties are as follows: rigid PU>PF>PS.
The thermal conductivity of the rigid PU is 0.01.0.03 W/(m.K), and the thermal conductivity of the PF is 0.02-0.04 W/(m.K), which is second only to the hard PU, while the PS is slightly worse. Because foams for thermal insulation are mostly used at higher temperatures, attention should be paid to the heat-resistant temperatures of different varieties when selecting them. The PS is 80 ° C, the PU and urea formaldehyde are 95-100 ° C, the PF is 120-130 ° C, and the PVC is 60-70 ° C. Therefore, PS and PVC should be used at low temperatures, and PU and PF should be used at high temperatures. Urea-formaldehyde foam has good heat insulation properties, and has the advantages of flame retardancy, low price and wide source; however, it is widely used due to its brittleness and water absorption. Now using on-site foam molding method, it can be widely used in building insulation to reduce the heat loss of houses by 70%.
Although it is not widely used in China, it is very common in the United States. In practical applications, specific insulation foam products include: insulation boxes such as refrigerators, seafood boxes, PS beads foam products; fast food lunch boxes, PS low foam products; roof sheds, house walls, etc. PS beads foam board , PF foam products, urea-formaldehyde foam plastic; refrigerator backboard insulation layer, pipe insulation layer, rigid, PU foam material.