Heat sealing

Abstract

Abstract 1,152,593. Seaming non-metallic sheet material. UNION CARBIDE CORP. 9 Aug., 1966 [9 Aug., 1965; 8 April, 1966], No. 35604/66. Heading B5K. [Also in Division H5] Heat sealing apparatus includes a heat sealing member comprising a rigid bar 14 which is movable relative to a back-up member 16 serving as a support for superimposed thermoplastic films 18, 21 to be joined, the bar 14 carrying a heating element 20 comprising a woven tape or rubbon 10 of an electrically insulating and thermally resistant material, such as fibre glass, asbestos or quartz, and a plurality of strands of an electrically conductive material 12 interwoven with ribbon 10. Heating element 20 has an outer coating of polytetrafluoroethylene and is secured to bar 14 by insulating tape 22, 24. The support bar 14 is water cooled and acts as a heat sink. The voltage is applied as an intermittent high impulse voltage, or as a low preheating voltage with an intermittent high impulse voltage, or as a steady voltage less than impulse level voltage. The woven tape is impregnated with thermally resistant resin, and has a central heating region H which contains conductive strands 12. Strands 12 are carbon, tungsten, rhodium, beryllium, molybdenum, iridium, ruthenium, osmium, palladium or NICHROME (Registered Trade Mark). They may be gold-plated.

Inventors

• 👤 Emerson Bradford Donnell Jr
• 👤 William L Calvert

Bibliographic Details