| 摘要 |
PROBLEM TO BE SOLVED: To obtain a foam having specified density, thermal dimensional change, compression strength, and thermal conductivity with a good flowability and extrudability without the necessity for a flowability improver by using a polystyrene resin having a specified melt index. SOLUTION: A polystyrene resin foam having a density of 16-23 kg/m<3> is obtd. by extruding a melt mixture contg. a polystyrene resin having a melt index of 0.5-6.5 g/10 min, a blowing agent, and other necessary additives from a high-pressure zone into a low-pressure zone. Thus obtd. foam has thermal dimensional changes in both the length and width directions of 0.6% or lower at 70 deg.C (based on the dimensions before heating) and has a compression strength of 1.0 kg/cm<2> or higher, a thermal conductivity of 0.035 kcal/mh deg.C or lower, and an average cell size of 0.45-2. 5 mm. The melt mixture before extrusion contains an inorg. cell-controlling agent and pref. at least one blowing agent having a solubility parameter different from that of the resin by 2 cal/cc or lower. |
