| 摘要 |
993,726. Seaming non-metallic sheet material; laminates. TETRA A.B. Nov. 1, 1963 [Nov. 23, 1962], No. 43289/63. Headings B5K and B5N. In a method of heat-sealing a material comprising a body layer coated on both sides with thermoplastic material in which two layers of the material are compressed by clamping jaws and heat is transmitted from at least one jaw to melt the thermoplastic coatings so that the two inner coatings fuse together, the material is allowed to cool and then during release of pressure and removal of the jaws heat is again transmitted to melt the outer layers of thermoplastic, without attaching the inner layers, to prevent the outer layers adhering to the jaws. The heating of the jaw(s) is continued after removal until any thermoplastic material deposited thereon is decomposed. In an example a tube coated on both sides with a thermoplastic material such as polythene is heat-sealed transversely to form individual packages, the heating means being formed by a thin metal band on one of the clamping jaws heated by passing an electric current therethrough. |
