Manufacturing container or tube from paper; or other manufacturi – Container making – Pliable container
Patent
1997-07-31
1999-09-14
Scherbel, David A.
Manufacturing container or tube from paper; or other manufacturi
Container making
Pliable container
493210, 531342, 53413, B65B 2904
Patent
active
059514523
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to the manufacture of infusion packages, such as tea bags and in particular to a method and apparatus for the manufacture of tagged drawstring infusion packages having a length of slack string of the type described in WO 93/19997.
A method of manufacture for a tagged infusion package is described in WO 92/14649. In that method, a length of string between the tag and infusion package is firstly lightly adhered in a convoluted pattern to the outside surface of the continuous porous web which forms one side panel of the final infusion package. This is achieved by heating that web with a heated guide which faces one surface of the web and is effective to melt the thermoplastics coating on the web (which is also used to seal the webs together) such that the string can then be placed on and adhered to the other surface of the web which becomes the external surface of the assembled infusion package. After that, the web with the string on it is sealed to the other web on which the dose of tea, for example, has already been placed, to form a tea containing pocket which is then cut out to form a sealed infusion package. As the string is adhered to the outside surface of the infusion package, it remains in place during and after manufacture, such that loose string does not interfere with the manufacturing process or become entangled in a subsequent container, for example. The string is lightly adhered to the package (apart from its anchoring point which is firmly secured) in a tortuous pattern which can readily be released by a user without damaging the web material.
In the method of WO 92/14649, the string is adhered to the surface of the web which becomes the outside surface of the infusion package, and the heated guide for melting the thermoplastics coating on the web is arranged to face the eventual inside surface of the web. Thus in practice it is mechanically convenient for the heating and string location to take place from opposite sides of the web. However, the porous webs used to manufacture infusion packages are necessarily designed such that when heated the thermoplastics coating provides significantly greater adhesion on the inside rather than the outside surface (since the inside surfaces must be capable of being firmly heat sealed together around their outer peripheries to form the infusion packages). Thus in WO 92/14649 the string is applied to the less adhesive outer surface. The Applicants have recognised that supplying sufficient heat to the less adhesive outer surface to secure a string pattern thereon can lead to a tendency for the other, more adhesive side, of the web to adhere to its guides, which can cause it to tear, or even stop completely. The problem is exacerbated if the heating is supplied through the web from the internal side, as in the most convenient arrangement.
According to one aspect of the present invention, there is provided a method for manufacturing tagged infusion packages of the type formed from a two-ply web having an infusion containing pocket defined therein and a length of string joining the tag and package, comprising: packages; patterns, the patterns being arranged in such a manner as to provide in the final infusion package a slack length of string held within the infusion containing pocket prior to use such that pulling the tag away from the infusion containing pocket initially causes the slack length of string within the pocket to be withdrawn therefrom; surface of one of the travelling webs which will become an inner surface of the pockets; the infusible substance in such a manner that, within each pocket, the string is lightly adhered in said predetermined pattern to the inner surface of one of the webs, with one portion of the string being held by means of sealed together portions of the webs, the slack length of string extending within the pocket, and a further portion of the string extending slidably through the seal at the margin of the pocket; predetermined shape each containing within the pocket said portion of string in the pred
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patent: 2447014 (1948-08-01), Irmscher
patent: 2447258 (1948-08-01), Lobley
patent: 2472440 (1949-06-01), Salfishberg
patent: 3191355 (1965-06-01), Morpurgo
patent: 4609556 (1986-09-01), Goedert
patent: 4829742 (1989-05-01), Romagnoli
patent: 5511359 (1996-04-01), Kenney
Ojini Anthony
Scherbel David A.
Tetley GB Limited
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