| 摘要 |
<p>1372524 Yarns W C HELLER JNR 16 Sept 1971 [22 Sept 1970] 43170/71 Heading D1W [Also in Division B6] A number of leaves are sewn together to form a book section by means of a thread which when subjected to indirectly applied energy i.e. an alternating electric or magnetic field, becomes heated to cause bonding material to become adhesive so as, together with the sewing, to join the leaves. The bonding agent may be applied to the leaves prior to, or after sewing, or may be incorporated on the thread. As an example of the latter arrangement, the thread may consist of a filament of a dielectric material e.g. polyvinyl chloride which is heated when exposed to an alternating electric field, or may comprise a filament coated with such material, the material forming the bonding agent when rendered thermoplastic by the heating. The thread 18, Figure 3 may be made heatable by dispersing in the bonding material 28 or impregnating the thread with particles 30 of iron oxide, metal, or ferrite which when subjected to an alternating magnetic field become heated. The bonding material may be a thermoplastic e.g. a water emulsion of ethylene vinyl acetate, or a thermosetting material e.g. an epoxy. In Figure 4, the sewn leaves are placed with the fold between two coils 32 energised by an alternating current from a source 34 to set up a magnetic field. The coils may be mounted on supports 38 serving as pressure platens. During the heating and pressure operation, the stitches become fused together and bonded to the sewing holes and to the leaf portions between the holes. Reference has been directed by the comptroller to Specification 1220573.</p> |
