| 摘要 |
1,129,127. Powder sintering. SUMITOMO CHEMICAL CO. Ltd. 18 Feb., 1966 [27 Feb., 1965], No. 7239/66. Heading B5A. Multi-layered thermoplastic resinous articles including one foamed layer, are formed by powder sintering successive layers in a heated metallic mould, the material forming the foamed layer incorporating a foaming agent decomposable at a temperature higher than the melting point of the material. In one embodiment, to form a three layered article, resin powder is fed to the mould, sintered to form a layer and the excess removed. A powder including a foaming agent is then fed to the mould, heated to form a sintered layer and the excess removed, and subsequently heated to a higher temperature to completely decompose the foaming agent and form the foamed layer. A third sintered layer is then applied in the same manner as the first and the whole then heated to smooth the surface of the article. If the third layer is sufficiently thin then it may be sintered by the residual heat retained by the mould and the first two layers the article being smoothed as before. In a second embodiment the first layer is applied as before and then a sintered foamable layer is formed which layer is then heated to partially decompose the foaming agent. The third layer is then applied as before and the whole finally heated to fully decompose the foaming agent and to smooth the surface of the article. Two layered bodies are formed by merely omitting the last layer. |
