Patent GB-1165856-A (GB)
Title: Method and Apparatus for the Continuous Manufacture of Flexible Plastics Tube Material
IPC: B29C48/09
Filed: 1968-05-03
Abstract: 1,165,856. Extruding tubes; making bags; seaming non-metallic sheet material. MINIGRIP EUROPE A/S. 3 May, 1968 [3 May, 1967; 28 June, 1967], No. 21218/68. Headings B5A, B5B, B5D and B5K. [Also in Divisions B8 and E2] In the manufacture of plastics tubing having longitudinally extending releasable fastenings, which tubing is particularly intended for the production of bags or sachets, the tube is extruded, and preformed releasable fastenings are attached to either the outer or inner surface of the tube downstream of the extrusion die, the speeds of advance of the tube and the fastenings being the same at the place where they are united. In the embodiment of Figs. 1 and 3, an inflated tubular film 1 is extruded from an orifice 2 and engaged fastenings 15, 16 are introduced to the interior of the tube via a preheater 19 and a passageway in die 3 and mandrel 3a. The fastenings 15, 16 are attached to the film 1 by forming a longitudinal fold in the latter by means of rollers 20, 21, Fig. 3, adjacent a radially extending finger 22 attached to central post 25, Fig. 1. The fastenings are separated by finger 22 and the fixing flanges 15a, 15b, 16a, 16b of the fastenings are heated by resistance elements 23, 24 in finger 22 as rollers 20, 21 press the flanges and film into contact with one another, finger 22 acting on an anvil. Rollers 20, 21 may be heated in addition to or instead of finger 22. After welding of the fastenings they are re-engaged by rollers 28, 29. Fastenings 15, 16 may be introduced within the film disengaged. In the embodiment of Figs. 7 and 8 (not shown), engaged fastenings (33, 34) have their fixing flanges (36a, 37a) preheated by heater (38) and the fastenings are applied externally to inflated tubular film 1 by rollers (41, 42). In addition, the film is produced with a longitudinal groove (32) by means of a projection (31) at the die orifice and this groove becomes situated between flange (36a) and the engageable portion of fastening (33), Fig. 8 (not shown). In a modification, Figs. 9-11 (not shown), a cut is made in the film instead of, but at the same location as, groove 32, by means of a blade (49) attached to a cutting device (47). This device is inserted downstream of rollers (43), Fig. 10 (not shown), and a finger (44) which separates the fastenings. The latter are re-engaged by rollers (50, 51). In a third embodiment, Figs. 12, 13 (not shown), fastenings (33, 34) are attached to the film 1, at a point where the latter is non-tacky, by means of welding rollers (54, 55) co-acting with an anvil (56) within the film. In the first embodiment, Figs. 1 and 3, and Figs. 2, 4 and 5 (not shown), the product may be formed into sachets, Fig. 6 (not shown), by transversely cutting and welding the film as at (9, 9a) and longitudinally cutting the film as at (10). In the embodiment of Figs. 7 and 8 (not shown), a sachet may be made having initially a double closure, i.e. the interengaged fastenings (33, 34) and groove (32). Such a sachet is opened by pulling tab (35), Fig. 8 (not shown), of fastening (33) to first disengage the fastenings and then to tear the sachet along groove (32). It is also mentioned that the product may be used as a tubular sheath for electric wires. Polyethylene and polyvinyl materials are specified.