| 摘要 |
An extruded propylene polymer resin foam having a wall thickness of 20 mm or above, a density of 0.005-0.03 g/cm 3 , an average cell diameter of 0.4-2.0 mm, and a closed cell content of 80 % or above. It has a large number of closed cells and is produced from a propylene polymer resin having such high viscoelastic characteristics that the biaxial elongation viscosity and the biaxial strain curing rate (* small Greek alpha *) as defined by the following equation are, respectively, 3.0x10 6 P or above and 0.25 or above when the biaxial elongation strain is 0.2: * small Greek alpha * = 0.77 x (log* small Greek eta *2 - log* small Greek eta *1 ) wherein * small Greek eta *1 and * small Greek eta *2 represent biaxial elongation viscosities, respectively, when the biaxial elongation strains are 0.01 and 0.2. The foam is lightweight and has high cushioning characteristics and excellent mechanical strengths. Hence it is cut into various forms and utilized in the fields of cushioning packaging materials, floating materials and also heat-insulating materials. |
