| 摘要 |
Prodn. of low-density foamed articles by heating finely-divided expandable prefoamed styrene polymers with steam in a non-hermetically closing mould is described. Novelty comprises treating the insufficiently prefoamed expandable particles with a steam-air mixt. to form a fluidised bed. After expansion, the steam-air mixt is temporarily replaced by air and foaming is completed with steam. Prefoaming and cooling time can be shortened. Intermediate air-treatment conditions the expanded particles. Foams are uniformly heat-sealed and have uniform density. Prefoamed polystyrene particles having bulk wt. 22 g/1 were treated 60 secs, with a steam-air mixt. at 128 degrees C and 20 secs. with air at room temp., followed by steaming. Foamed articles had bulk wt 15-16 g/1. |
