| 摘要 |
: A method for providing and apparatus utilizing a water soluble closure in a fill valve for valve type single or multiwalled bags to produce a positive sift-proof seal of the fill valve includes the provision of a film of water soluble polymer material in the mouth of a valve type bag with the film substantially co-extensive with the width of the bag mouth so that on exposing the film to water as by steam or liquid application at least some dissolving of the film occurs with consequent sealing of the bag mouth when the mouth is held closed upon the film by manual or mechanical means, during which the film re-solidifies due to the evaporation of the applied water and due to the tackiness of the material adheres to and seals the bag or valve mouth. In one form of the method and apparatus, the film is formed as a sleeve with or without a backing or reinforcing strip or sleeve which is fitted into the bag mouth to provide a valve mouth or filling access opening to the bag through the interior of the sleeve whereby upon application of water to the interior of the sleeve and laterally collapsing the same, the valve mouth so provided is welded shut. In other forms of the method and apparatus, the film of water soluble polymer material is provided in sheet form with or without backing or reinforcing sheets of co-extensive size with the bag filling valve mouth formed alternatively between the film sheet and the surrounding portions of the bag or between the film sheet and the reinforcing sheet. |
