Bottles and jars – End wall structure – Apertured end wall
Patent
1998-12-30
2000-08-29
Moy, Joseph M.
Bottles and jars
End wall structure
Apertured end wall
215385, 215902, 220 6221, B65D 9002
Patent
active
061094684
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a receptacle produced in a coextrusion-type blow molding process, which consists of a substantially stiff outer receptacle and an easily deformable inner bag which are made from respectively different thermoplastic materials that do not form a welded joint with one another, said receptacle comprising a receptacle opening and at least two pressure compensating openings provided in the wall of the outer receptacle for pressure compensation within the space existing between the outer receptacle and the inner bag upon contraction of the inner bag, wherein, when excess material is squeezed off at the bottom of the blow mold, the inner bag is closed by a bottom weld seam and said bottom weld seam is clamped into the bottom of the outer receptacle which is also closed.
Such a receptacle is described in DE 41 39 55 C2. In this known receptacle, the bottom of the outer receptacle has formed thereon an outwardly projecting web in which, while the blow mold is being closed, material of the outer receptacle is united as the material of the inner bag recedes inwards from the squeeze-off edge due to an impact pressure b uilt up in the area of the protruding Web. As a consequence, material of the outer receptacle contacts itself over part of the height of the aforementioned web, resulting in the formation of a closed weld seam. The bottom weld seam of the inner bag is anchored in the adjoining area of the web. The web can, for example, have an approximately kite-shaped cross-sectional form, but other cross-sectional shapes of the web, for example arched ones, will also yield a welded bottom seam of the outer receptacle. As for further details regarding the production of the prior-art receptacle, reference is made to DE 41 39 555 C2.
However, the bottom weld seam of the inner bag can also be secured in a different way to the bottom of the outer receptacle, for instance by means of suitable slides in the blow mold.
In the prior-art receptacle, the pressure compensating openings on the outer receptacle are formed in that the tube-shaped blank is squeezed off in the shoulder portion while the blow mold is being closed, with the material being smoothly squeezed off without the formation of a projecting web, so that the two material layers of the outer receptacle do not contact each other as such a contact is prevented by the interposed double layer of the inner bag. As a result, in the prior-art receptacle, two unwelded seams are formed in the shoulder portion in the outer receptacle, the seams extending from the shoulder portion up to the neck portion.
When viewed in the circumferential direction of the receptacle, these pressure compensating openings at both sides are positioned at locations which are aligned with the points of intersection of the bottom weld seam with the circumferential seam of the receptacle. In other words, these pressure compensating openings are located in circumferential direction on the lines of intersection of a plane passing through the central longitudinal axis of the receptacle and the bottom seam, with the circumferential wall of the receptacle.
Insofar as points of intersection of the bottom weld seam with the circumferential wall have been mentioned above, such a design also covers a case where the bottom weld seam does not extend over the whole diameter of the receptacle, whereby in such a case the points of intersection are formed by a line which extends the bottom weld seam.
Upon discharge of the receptacle contents, for example by means of a pump, the volume of the inner bag is reduced, and air exits for the purpose of pressure compensation from the surroundings of the receptacle into the space existing between inner bag and outer receptacle. A certain negative pressure or vacuum which keeps the inner bag in its contracted state always remains in the receptacle.
In the prior-art receptacle, the inner bag, when viewed in horizontal section, i.e. in a plane perpendicular to the longitudinal axis of the receptacle, will contract substantially in star-shaped c
REFERENCES:
patent: 2743038 (1956-04-01), Ferries
GAPLAST GmbH
Moy Joseph M.
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