| 摘要 |
<p>The invention relates to a plunger for use in excluding air from a container and especially from a cartridge dispenser. The invention comprises a plunger adapted to be inserted into a tube and having a leading face which may be inserted by a predetermined distance into the tube before forming a seal therewith. After insertion of the leading face by the predetermined distance, the plunger forms an air tight seal with the tube. The plunger is insertable into the tube by a further distance beyond the predetermined distance without reduction in the volume thereby contained. In preferred embodiments the means enabling insertion of the plunger to a distance before a seal results comprises one or more grooves extending along the plunger side wall from the leading face towards a trailing edge but stopping short thereof. The preferred means enabling a further insertion without reduction in volume contained comprise a membrane integral with the leading face which is deformable in a trailing direction. When inserted in a cartridge dispenser means may be provided whereby movement of the plunger in a trailing direction beyond a predetermined position may be prevented thereby maintaining the seal while permitting dispensation of contents.</p> |
