| 摘要 |
Ampoules having a non-return valve for packaging liquid and semi-liquid prods. are produced by (a) leading the film material in the folded state through a guide device, in which at least one edge of the film material is bent inwards, (b) placing a heat insulating base between the lower film layer and the inwardly folded edges, after the film material has left the guide device, (c) passing the film material to a heat welding station, and (d) welding together the upper film layer, and the inwardly folded edges on the base to form the valve, by means of spot welds or short welds extending axially along the ampoules at mutual distances that are smaller than the width of the ampoule. Reliable sealing of the ampoules and precise formation of high quality valves are possible. Method is suitable for mass prodn. |
