| 摘要 |
<p>A cellular synthetic resin product is made from expanded pearls by heating the latter to their softening temperature, compressing to impart the required thickness and final density of the product and cooling under compression sufficient to maintain the thickness. The beads can be heated by hot air or by steam under pressure. During compression, the pearls are kept at the temperature reached during heating. The apparent density must be selected in dependence on the final density of the product required. For a given final density the most favourable ratio between it and the apparent density is from 0.4 to 0.6, preferably 0.5. The density of the expanded pearls used is not more than 5 kg/m.3. The process may be carried out continuously or discontinuously. When the process is carried out discontinuously the expanded pearls are introduced into a mould having a perforated bottom and a movable perforated cover The beads are heated by blowing air through the mould at a temperature higher than the softening temperature of the beads, compressed by lowering the cover, and cooled. To carry out the continuous process the beads are introduced from a hopper between two conveyer belts and are heated by hot air. This first pair of conveyers may be parallel or slightly inclined to one another to effect some compression of the beads. The beads then pass between a second pair of belts which are parallel and more narrowly spaced than the first pair so that the beads are compressed. The beads are heated by hot air in the first section of the space between the second pair of belts and cooled in the second section. The only example given is of the production of a cellular synthetic product from expanded polystyrene beads.</p> |
