VERFAHREN ZUR HERSTELLUNG EINES GASDICHTEN KUNSTSTOFFVERSCHLUSSES FUER FLASCHEN UND DERGLEICHEN BEHAELTNISSE.

摘要

An air-tight plastic closure for bottles and similar is produced by a two-part process in which a first closure is injection moulded, this is then moved a set distance from the mould core, and the second material is injected into the space produced. The first is a hard type and the second a softer type polyethylene. In a vertical machine the main closure is injection moulded in a hard polyethylene through the gate into the split line, using a male core tool. This core is next withdrawn (or rotated) by a set distance. Alternatively, the first moulding can be moved. In either case an intermediate space is thus formed, and this is then filled by injecting the soft type polyethylene through the gate. The second shot bonds well to the first and enables the finished bottle to be well sealed even after being repeatedly opened and closed again. The movement of the core for the second shot is usually 0.5 to 1 mm. The ejector system is conventional.