| 摘要 |
1,200,827. Moulding foamed thermoplastic articles. FURUKAWA DENKI KOGYO K.K., and NISSEI KOGYO K.K. 2 Oct., 1968 [2 Oct., 1967], No. 46813/68. Heading B5A. A shaped foamed thermoplastic article is formed by foaming a thermoplastic composition in a mould pierced by a plurality of small holes while rotating the mould. The thermoplastics composition comprises a thermoplastic material and a blowing agent and is foamed by heating, the composition optionally containing a blowing agent or being subjected to ionizing radiation before foaming. The thermoplastic material is preferably a thermoplastic resin or a mixture thereof and may contain up to 50 wt. per cent of natural or synthetic rubber. It may contain fillers and flame retarding agents and the composition may be mixed in a blender or kneaded or pulverized to a powder, flakes or granules. The holes which are preferably 1-4 mm. in diameter may be located over the whole surface of the mould or may cover only certain areas, preferably remote from the axis of rotation. A gas permeable material e.g. paper or cloth may be applied to all or part of the inner surface of the mould. The mould may be rotated continuously or intermittently at 10-300 revolutions per hour and may be heated by hot air or steam. The article formed may be a pallet, surfboard, boat, drum or container. Many examples of suitable polymers, blowing agents, curing agents and fillers are given. |
