| 摘要 |
PURPOSE:To obtain a molding having a good surface appearance and excellent dimensional accuracy, shrinkage, compressive hardness, etc., by imparting expandability to pre-expanded PP resin particles having a specified crystal structure and a specified decreasing rate of an internal pressure, filling a molding die with the particles, and expansion-molding them. CONSTITUTION:Expandability is imparted to pre-expanded particles which have such a crystal structure that a DSC curve obtained when 1-3mg of the pre- expanded PP particles are heated to 220 deg.C at a temperature rise rate of 10 deg.C/ min on a differential scanning calorimeter has a high-temperature peak on the high temperature side in relation to the temperature of the intrinsic peak inherent in the PP resin, and show an internal pressure drop rate at 25 deg.C and 1atm, k, in the range: k<=0.30. These particles are placed in a molding frame and heat-expanded to produce a molding of the shape of the mold. According to this process, it is possible to obtain a molding having a good surface appearance, excellent dimensional accuracy, and excellent properties such as shrinkage, compressive hardness, compression set, and fusion of particles. |
