Flexible bags – With venting or ventilation means – Opening in bag material
Patent
1996-11-27
1998-03-17
Pascua, Jes F.
Flexible bags
With venting or ventilation means
Opening in bag material
22020311, 22020315, 22020318, B65D 3301
Patent
active
057278814
DESCRIPTION:
BRIEF SUMMARY
PRIOR ART
The invention is based on an overpressure valve for a packaging container. Products that are vulnerable to oxygen, such as coffee, are packed in tightly sealed containers to prevent spoilage from oxygen in the air. However, since freshly roasted coffee produces carbon dioxide and hence builds up a pressure that bloats the package, causing it to burst, it is known to equip the packaging container with an overpressure valve. An overpressure valve, known for instance from European Patent Disclosure EP-A 0 023 703, which is disposed through a hole in the wall of the packaging container, has a flexible valve diaphragm that covers a circular valve hole in a base plate glued in sealed fashion to the wall of the packaging container, and which at a certain internal package pressure lifts up from the base plate, forming an outlet channel through which carbon dioxide gas can flow out of the package into the open. Even a slight internal package pressure unattractively bloats a bag package of flexible packaging material. In the above-mentioned overpressure valve, which has proven itself on the market, the opening pressure is approximately 5 mbar. To reduce the opening pressure, the present applicant, in the earlier German Patent Application P 44 35 492.4, has already proposed replacing the circular valve hole with an oblong hole. With this provision, the opening pressure can be lowered to about 3 mbar. A disadvantage, however, is that the tool for punching the oblong hole is relatively complicated to manufacture, since to attain a high-quality cutting edge a play of only a few micrometers can be present between the female and the male dies. It has also been found in practice that particularly with a circular hole, if there is a negative pressure in the packaging container, such as occurs on evacuation during closure of the packaging container, creasing of the valve diaphragm can occur. Such creasing causes a leak in the packaging container.
ADVANTAGES OF THE INVENTION
The overpressure valve for a packaging container according to the invention, has the advantage over the prior art that the tool for producing the valve hole can be manufactured more simply and thus less expensively. It is also possible, with the hole shaped according to the invention, to attain an at least equally low opening pressure as with the oblong hole. It has also been demonstrated that creasing of the valve diaphragm which previously occurred if there was a negative pressure in the packaging container no longer occurs when the valve hole is shaped according to the invention. It is also advantageous that sealant supplied centrally into the valve hole for sealing between the base plate and the valve diaphragm penetrates especially rapidly into the channel zone.
Further advantages and advantageous further features will become apparent from the description set forth below.
BRIEF DESCRIPTION OF THE DRAWING
One exemplary embodiment of the invention is shown in the drawing and will be described in further detail in the description below. FIG. 1 shows a packaging container with an overpressure valve in a perspective view; FIG. 2 shows the overpressure valve of FIG. 1 on a larger scale in plan view, and FIG. 3 shows the overpressure valve of FIG. 2 in cross section, in the plane III--III of FIG. 2.
DESCRIPTION OF THE EXEMPLARY EMBODIMENT
On a side wall of a packaging bag 1, in which freshly roasted coffee, for instance, is packed in a sealed fashion, an overpressure valve 10 is secured in sealed fashion to the wall 2 above a through hole 3. The overpressure valve 10 has a stiff base plate 11 of a plastic film or sheet in the shape of a square with rounded corners, and with a central hole 15 which is larger than the hole 3. A valve diaphragm 12 made of a flexible, thin plastic film or sheet, coincides with the base plate and includes two parallel spacer strips 13, 14 of a stiff plastic film or sheet.
By means of an adhesive layer 16 on the outside of the wall 2 of the packaging bag 1, which surrounds the hole 3 in the bag the overpressur
REFERENCES:
patent: 830859 (1906-09-01), Smith
patent: 4122993 (1978-10-01), Glas
patent: 4206870 (1980-06-01), DeVries
patent: 5263777 (1993-11-01), Domke
patent: 5427839 (1995-06-01), Buchner et al.
Greigg Edwin E.
Greigg Ronald E.
Pascua Jes F.
Robert & Bosch GmbH
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