| abstract |
A method for producing an extruded heat-insulating foam board having a thickness of 10 to 150 mm, an apparent density of 20 to 50 kg/m 3 and a closed cell content of at least 80% by extrusion foaming of a foamable resin melt containing a base resin composed primarily of a polystyrene resin, a physical blowing agent and a flame retardant, wherein 3 to 50 mol% of a hydrofluoroolefin, 30 to 70 mol% of a saturated hydrocarbon having 3 to 5 carbon atoms, and 5 to 50 mol% of water and/or carbon dioxide (where the sum of the contents of the hydrofluoroolefin, saturated hydrocarbon having 3 to 5 carbon atoms, water and / or carbon dioxide is 100 mol%) are used as the physical blowing agent. The extruded polystyrene resin heat-insulating foam board is produced with good extrusion foamability and moldability and has a high expansion ratio, a large thickness, excellent long-term heat-insulating properties and flame retardancy, and good appearance. |