| 摘要 |
PROBLEM TO BE SOLVED: To provide expandable polystyrenic resin particles for a heat insulating material used as a roof ground material, into which a flame retardant can be uniformly impregnated and which when expanded, ensure a uniform density distribution of foams, have such a level of heat resistance that a dimensional change rate in heating at 90°C for 168 h is within ±0.5%, exhibit excellent thermal insulation property, excellent property of filling into a cavity in molding, and excellent heat fusing property of the particles to one another in molding, and can give a molded foam product with excellent flame retardancy, and to provide a heat insulating material for a roof ground material.SOLUTION: The polystyrenic resin particles having a coefficient of variation (CV) in particle diameter of 5-15% are dispersed in an aqueous suspension, and before or during impregnating a blowing agent, a flame retardant solution prepared by dissolving 40-300 pts.wt. of a 2,2-bis[4-(2,3-dibromoalkoxy)-3,5-dibromophenyl]-propane as a powdery flame retardant in 100 pts.wt. of a plasticizer is fed into the aqueous suspension and the flame retardant is impregnated into the polystyrenic resin particles. The resulting expandable polystyrenic resin particles are pre-expanded and the pre-expanded particles are filled into a mold and expanded to obtain a molded polystyrenic foam product having an average chord length of 30-380 μm. |
