| abstract |
949,338. Seaming non-metallic sheet material. SOUTHERN CALIFORNIA PLASTIC CO. Nov. 1, 1961 [April 20, 1961], No. 39076/61. Heading B5K. [Also in Division F4] A heat-insulated container is formed by spin welding a liner within a shell to define an enclosed space therebetween. Shell 12, held by a chuck, is rapidly spun (3,000 r.p.m.) with respect to liner 10, whilst a polymethane is foamed and distributed throughout the space 54 therebetween, until the frictional heat welds rim 20 with V-shaped groove 50. A small hole 60 permits the escape of entrapped air. A suitable polymethane formulation comprises, by weight, 49.0 parts toluene diisocyanate, 0.25 silicone compound, 37.5 polyether, 13.0 monofluorotrichloromethane, 0.25 triethylene diamine. Alternatively, the space 54 may be filled with pre-expanded pre-formed polystyrene. Shell 12 and liner 10 are domed at 16 and 24 to allow for variations in foamed volume. The minimum separation of shell 14 and liner 10 is # inch. In another embodiment, Fig. 5, a tumbler having a thicker upper lip 26a is formed. Materials suitable for liner and shell are polyethylene, polyvinylchloride, polyvinylacetate, polystyrene, polytetrafluoroethylene, polytrifluorochloroethylene, polymethylmethacrylate, polypropylene, the acrylics and nylon. |