| 摘要 |
Moulding heat-expandable thermoplastic. Process comprises confining heat-expandable beads of the material within a mould and then heating the beads so as to fuse them together where the beads are deposited in the mould in two or more layers, the beads of one layer having no pre-expansior or being pre-expanded less than the beads in another layer so that the part of the article formed by the one layer of beads is denser and stronger than the part of the article formed by the other layer of beads. |
