| 摘要 |
937,755. Seaming non-metallic sheet material. SCHOLL MFG. CO. Ltd. Dec. 22, 1959 [Jan. 7, 1959], No. 43590/59. Class 42 (1). In a method of sealing a layer of thermoplastic film to a layer of thermoplastic foam, a die preheated to a temperature below the melting points of the materials is forced against the superposed materials and then energized with a H.F. current. The film 17 preferably of unsupported vinyl, e.g. polyvinyl chloride and foam 16 preferably of polyester polyurethane or polyvinyl chloride, are placed on a lower electrode 8. The die 1, 2 which is shaped to define an article, e.g. a bath mat, seat cushion, insole or other foot cushioning device, forms a tearing line so that the waste material may be stripped from the article after sealing. A heating element 5 is used to preheat the die 1, 2. A sheet 9 of phenolic material or other dielectric insulating material and a sheet 10 of a tetrafluoroethylene or a fluoro-carbon resin to which the polyurethane foam will not adhere, may be placed on the lower electrode 8. |
