Sliding clasp fasteners - with plastic (pvc)backing tapes reinforced with cotton stitching to improve tear resistance

摘要

Thermoplastic tapes to support teeth for a slide fasteners are unrolled under slight tension while inextensible threads, pref. of cotton, are secured along each face of the tape. The sets of fastener teeth are subsequently mounted using stitches which interlace with those previously applied. Pref. the needles used have a high surface/mass ratio and are cooled during use by air jets etc. Esp. for slide fasteners featuring metal or plastic teeth mounted on PVC backing tapes typically 1.3-2 cm. wide and 0.2-0.3 mm. thick. Pref. the equipment used during stitching is coated with a low friction material, specif., "Teflon" (RTM). Pref. the fastener teeth are moulded in 'Nylon' (RTM) or 'Tergal' (RTM). The stitching integral with the thermoplastic tapes improves tear resistance. The special needles can process the tapes at about 4,000 stitches per minute without overheating.