Plastic tubing crimp seals

Semi-solid products have been traditionally packed in collapsible tin tubes. Metal tubes are a potential source of metal particles in ophthalmic products, and so the tubes have to be cleaned carefully prior to sterilisation. Also, the final product must meet limits for the number of metal particles found. Plastic tubes are not suitable because of their non-collapsible nature, which causes air to enter the tube after withdrawal of each dose. However, collapsible tubes made from laminates of plastic, aluminium foil and paper are a good alternative to tin tubes. Laminated tubes fitted with polypropylene caps can be sterilised by autoclaving, whereas tubes fitted with polyethylene caps are sterilised by gamma irradiation. The tubes are usually filled aseptically, sealed with an adhesive and then crimped. 

The top seal (overseal) may be a small stopper, a modification of a stopper, a disc or a combination-type system. Each normally requires rubber under compression held in position by an aluminium crimped, rolled-on, etc. overseal. The second sealing surface may be glass or plastic. In the case of glass cartridge tubes, these are invariably produced from the tubular or cane glass process, hence suffer from imperfections associated with this shaping process. Plastic cartridges have never proved popular but are available. 

Cone sleeves are made from a laminate of aluminium foil and paper. The top of the sleeve is crimped down over a cardboard disc to form a lid after product assembly is completed. Tubes are made from cardboard coated on both sides with polyethylene. The base is heat-sealed to make it leak-proof and the top is rolled to make a rim, onto which the lid is heat-sealed. Plastic tubs and containers are used for ice cream and... 

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