| 摘要 |
<p>1418670 Seaming non-metallic sheet material E I DU PONT DE NEMOURS & CO 1 Dec 1972 [3 Dec 1971] 29258/75 Divided out of 1418669 Heading B5K The subject matter is identical to that disclosed in Specification 1,418,669, but the claims relate to a method of forming at least one rupturable seal between two thermoplastic surfaces by (a) compressing the thermoplastic surfaces together between a resilient backing plate and a heating platen having at least one raised, continuous electrically conductive heating surface divided into a plurality of coherent sections, each in the shape of the desired rupturable seal and each supplied separately with electrical power; (b) while the thermoplastic surfaces are compressed between the heating platen and the backing plate, rapidly raising each region of the thermoplastic surfaces representing a rupturable seal to equal temperatures which are sufficient to bond together the thermoplastic surfaces with a bond strength markedly less than the maximum bond strength possible between them, by controlling the power supplied to each one region of the heating surface representing a rupturable seal; and (c) cooling the thermoplastic surfaces while they are still compressed between the heating platen and the backing plate.</p> |
