Reclosable bags with rib and groove elements formed of different materials

摘要

1,156,170. Extrusion dies. MINIGRIP (LONDON) Ltd. 21 Oct., 1966 [22 Oct., 1965], No. 47323/66. Headings B5A and B5B. [Also in Division E2] A material for use in the manufacture of a bag comprises a film of plastics material for forming the walls of the bag, having opposite parallel longitudinal edges, integral co-operating fastening elements 12, 13 spaced from and parallel to said longitudinal edges, said fastening elements consisting of a rib element and a groove element adapted to inter-engage with one another, when the film is folded over, grip flanges 19, 20 being formed between the rib and groove elements and the adjacent edge of the film, one of said grip flanges 20 being formed with a longitudinally extending bead 21 to facilitate separation of the flanges, when it is desired to grip the flanges to unfasten the fastening elements. A die for making the material includes an outlet 32 for extruding the film of plastics material in tubular form, an opening 42 adjacent said outlet 32 for forming the bead and a pair of openings adjacent the outlet 32 for forming the fastening elements. The bead opening is either on the same side as the openings for the fastening elements or on the opposite side. The bead is made from a thermo-plastics substance which is different from that of the film material and the die body 28 is provided with a separate and distinct flow channel 40 which conducts from a source the different thermoplastic substance for the bead, the thermoplastic substance for the film material and the fastening elements being conducted through a main channel 29; the material for the fastening elements entering tributory channels 33 from the main channel. In a modification however the fastening elements are made of a material different from that of the film material and for each element a separate channel is provided in the die body for this material. The different material or materials merges with the flow of the material forming the film at the extrusion outlet 32.