Patent Application
20050078887
The invention relates to the field of flexible containers in which an access port to the interior of the container is provided, to a method for the manufacture of such a container and to a welding tool for the carrying out of such a method.
Flexible containers, in particular pouches, which are manufactured from thermoplastic foil material, are widespread in various areas of application. For many applications, the flexible container has at least one access port which leads from the exterior of the container to the interior of the container and which serves for the emptying and/or for the filling of the container.
Such containers can be manufactured without great effort and at a low price, in particular as pouches. They can therefore be used without problem in medical applications as mass-produced articles with a disposable character. The pouch can be pre-filled with a liquid such as an infusion fluid or a dialysis fluid. Empty pouches are also used in order e.g. to be able to accept a liquid during a medical treatment.
In the simplest case, a hose can serve as the access port which is e.g. welded between two foils. The transition point of the connection seam, at which it, starting from the connection foil-to-foil, encounters the connection foil-to-hose, must withstand enormous strains in this process. Loads can occur due to high pressure waves after the falling of the pouch (fall strength) or also during proper use (e.g. hydrostatic pressure, infusion with pressure cuff). Such loads can result in the bursting or tearing of the pouch, with said transition point being the starting point for such damage in many cases.
Devices are also known to increase the stability in the region of the access port in which a boat-like insert is provided as the access port at which a usually rigid plastic body is centrally penetrated by an opening which serves as an access opening. Tapering prolongations adjoin it. The foils undergo a more constant, tangential extent at the transition point in this manner. While such an insert increases the stability, it is, however, more complex in handling and is associated with higher costs.
A foil pouch having a hose-like access port is described in EP 0 269 419 B1 in which, after the welding of the pouch, a tube-like cuff is applied around the hose port and the foil surrounding it in an injection molding step. This requires a further production step as well as additional material, which is in particular disadvantageous for an application in high volumes.
It is therefore the underlying object of the invention to increase the stability of a flexible container at the position of an access port, without this being accompanied by a real increase in effort and material costs.
The solution of this object takes place with the features of the characterizing portion of claim 1. Advantageous aspects are named in the subordinate claims dependent on this claim.
The invention is based on the observation that, on the introduction of a three-dimensional access port between two two-dimensional boundary areas such as foils, problems result with respect to the exact unwinding of the boundary areas onto the surface of the access port. This can be illustrated most clearly with reference to an access port made as a hose which is laid between two foils and in which a connection seam between the foils extends directly over the hose. The extent of the container or of the pouch present along the connection seam is reduced due to the hose running around along half of its periphery in each case. This reduction is, however, no longer present directly subsequent to the hose end which opens into the pouch. The hose usually projects—likewise for technical production reasons—into the interior of the pouch.
In the transition zone between the connection seam and the end of the hose, a tab-like zone is formed next to the welding seam in the event of a load, which can be caused solely by filling, with the foil contacting the hose in said zone. The foil only subsequently lifts off from the hose. The stability in this region can therefore be increased by an additional connection of the tab-like zone to the hose, without this being accompanied by a loss in volume, such as would the be case with a simply broadened welding seam. In addition, the force component which causes a peeling off at the transition from the foil to the hose in the event of a load (the pouch “tries” to enlarge the available width) is opposed by a force component which extends along the hose axis and thus perpendicular to the expansion force. Ultimately, it is thus relevant within the framework of the invention that the connection seam covers part of the section of the access port which projects into the container. The connection seam in this process projects on this section of the access port further into the interior of the container than in the region of the connection seam directly adjoining the access port at the side.
This measure only requires a simple modification of the welding tool; an additional production step is not necessary. Since the stability of the container is increased, it is even possible to reduce the wall thickness of the container material when required and thus to save material, provided the container thus present meets required specifications.
It lies within the framework of the invention that the flexible container in accordance with the invention consists of different area-like boundary parts wherein at least one is formed as a flexible foil and the access port is inserted between this foil and a second area-like boundary part.
In an advantageous embodiment, the second area-like boundary part is likewise a flexible foil.
In the simplest case, the access port is made as a hose. However, the invention also includes differently shaped access ports such as boat-like inserts.
In a further embodiment of the invention, in which the access port is inserted between two flexible foils, the flexible container consists of a folded piece of foil as well as of one longitudinal connection seam and two transverse connection seams, with the access port being arranged in one of these connection seams.
In an embodiment which is particularly easy to handle, the flexible container consists of a hose foil and two transverse connection seams, with the access port being arranged in one of these connection seams.
All forms of permanent connection processes are available for the connection seams. In particular welding seams and adhesive seams can be named here, with welding having particular importance due to the technical production advantages.
The most varied materials can serve as the starting material for the flexible foil of the pouch, provided they are suitable for the manufacture of connection seams with the materials to be connected. In most cases, these will be thermoplastics. It is, however, also feasible to use correspondingly thin metal foils.
It is also the underlying object of the invention to provide a method for the insertion of an access port between a flexible foil and a second area-like bordering part of a flexible container for the manufacture of a flexible container in accordance with the invention. The solution of this object is achieved by the features of the characterizing portion of independent claim 11.
It is likewise the underlying object of the invention to provide a welding tool for the carrying out of the method in accordance with the invention for the manufacture of a flexible container in accordance with the invention. The solution is achieved with a welding tool having the features of the characterizing portion of independent claim 12.
EP 1 072 531 A2 shows a flexible container having an access port designed as an access port in which diverse incisions are provided for the tearing and releasing of the hose port. In addition, the connection seam, which is present between two foils and extends over the inserted hose, is broadened in the direction of the part of the hose projecting into the container. This broadening also extends, however, transversely to the hose, i.e. also in the adjoining region, where it directly connects the two foils to one another.
An exemplary embodiment of the invention is described in more detail in the drawings. There are shown:
a an enlarged representation of the access port of
b an enlarged representation of the access port of
a the side view of an embodiment of a welding tool in accordance with the invention; and
b the welding tool of
In
A section 4a of the hose 4 projects beyond the connection seam 2 into the interior of the container. Due to the filling of the pouch, the foil material nestles along the line extending in a broken line in a region 5 against the section 4a of the hose, although the connection seam 2 does not include this region.
The access port is shown enlarged in
b shows this region for an embodiment of a flexible container in accordance with the essence of the patent. The connection seam 2 now also includes the tab-like region 5. This can absorb additional forces in order to increase the stability of this region of the pouch. The available pouch volume remains practically unchanged.
In
The block-like substrate body moreover has a second surface 12 which is inclined by an acute angle α with respect to the direction in which the groove 11 or the first surface 13 extends. The substrate body, in particular the area of the groove 11 and the first surface 13, can be heated for thermal contact welding.
The welding tool 10 is inserted as follows while using the method in accordance with the invention for the insertion of an access port between a flexible foil and as second area-like boundary part of a flexible container:
First, the access port made as a hose 4 is positioned between the foil and the second boundary part. The welding tool 10 is then placed on from the side of the foil such that the connection seam 2 to be established extends over the first surface 13 and the hose 4 is inserted along the groove 11, with the foil extending between the groove 11 and the hose 4. The second surface 12 is chamfered toward the interior of the container in this case. A correspondingly shaped counter-piece, not shown in any more detail, provides a sufficient fixing from the side of the second boundary part. If the second boundary part should likewise be made as a flexible foil, a second welding tool 10 is expediently moved to the second foil in a corresponding mirror-symmetrical manner. The subsequent welding process along the heatable areas provides the formation of a connection seam 2 which has a section as shown in
The angle α can have an optimized value in dependence on the application. It has been found to be particularly advantageous for it to lie between 30 and 60 degrees (with a right angle amounting to 90 degrees).
It is thus possible with the help of the invention to substantially increase the stability of a flexible container in the region of an access port, without this being accompanied by a complex production technique or higher material costs. First trials with a container in accordance with the invention have already resulted in a clear improvement in fall strength. A material saving can even be achieved with unchanged stability.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10206738.4 | Feb 2002 | DE | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP03/00741 | 1/24/2003 | WO |
