DE102011084508B4 - Plastic closure device for a tubular bag - Google Patents

Abstract

Plastic closure device (1) for a tubular bag made of plastic or a multi-layer plastic film, the plastic closure device (1) comprising at least one lower part (5) with a spout (7), a spout opening (8) and a flange (4), and wherein - an energy supply arrangement (10) is arranged on the flange (4) on its flange underside surface (9), which can be connected to the plastic material or the plastic film of the tubular bag by means of ultrasonic welding, and the energy supply arrangement (10) has at least one concentric to the pouring opening (8) energy-conducting rib (12) arranged in the peripheral area (11) of the flange (4), characterized in that there is a concentrating rib (13) on the underside of the flange (9), which runs centrically offset to the energy-conducting arrangement (10) and opposite the energy-conducting rib (12 ) protrudes higher from the flange underside surface (9) and immediately adjacent to the Aus casting opening (8), the concentration rib (13) extending along part of the inner circumference of the flange (4).

Description

The present invention relates to a plastic closure device for a tubular bag according to the preamble of patent claim 1.

The invention relates in particular to a plastic closure device for a tubular bag made of a plastic material or a multi-layer plastic film, in which the plastic closure device comprises at least one lower part with a spout, a spout opening and a flange. Such a lower part is provided for attachment to a tubular bag by means of ultrasonic welding, so it is itself also made of a thermoplastic material. In addition, with such a lower part, an energy introduction arrangement is arranged on the underside of the flange on the flange, which serves to conduct and concentrate the energy introduced by means of ultrasound in such a way that a reliable and tight welded connection is created between the plastic parts to be connected (tubular bag and flange). For this purpose, the energy-introducing arrangement has at least one energy-conducting rib arranged concentrically with the spout opening in the peripheral area of the flange.

It is therefore assumed that the solution according to the invention should be suitable for so-called tubular bags, usually called “pouches” in technical jargon. Such tubular bags are now usually often made from multi-layer plastic films. Known multi-layer plastic films have, for example, layer structures as follows: PP - AL - PE and PP - PETSiOx - PE. The ultrasonically weldable outer layer is therefore often made of polypropylene (PP) and the inner layer of polyethylene (PE). The intermediate layers are often used to protect against light.

It is also self-evident that the plastic closure device usually contains or can contain other components, such as an upper part in the form of a closure cap, an opening device and a guarantee band. However, because these components are well known per se and are not relevant to the functionality of the invention, they are either omitted entirely or, where necessary, only indicated for the sake of simplicity.

Known solutions for plastic closure devices that can be fastened by means of ultrasonic welding are shown, for example, in the document JP-2000016453 , whereby two energy-conducting ribs running concentrically to the flange edge are shown here, or the document JP-2000344264 , which shows the same plastic closure device for tubular bags, in which there is only one energy-conducting rib running concentrically to the edge of the flange.

Also the documents JP 2003-072817 A and WO 2007/149231 A2 disclose plastic closure devices for a tubular bag made of plastic or a multi-layer plastic film.

A problem in the JP-2000016453 As already mentioned, there is always a certain risk with ultrasonic welding of this type that so-called “pinholes” will form in the sealing foil in the area of the pouring opening. Pinholes are unwanted small leaks that affect the tightness of the tubular bag, which of course can lead to serious hygiene and shelf life problems, especially in food packaging. The exact cause of the formation of pinholes does not seem to have been completely clarified, so it can be assumed that the previous solution attempts are at least partly of an empirical nature. Overall, the JP-2000016453 not to contain any more detailed disclosure as to whether the solution with only two energy-conducting ribs running concentrically to the flange edge can also reliably prevent pinhole formation in other or merely similar designs.

Another problem that occurs in particular with plastic closure devices with an opening device with a cutting device is that in order to improve or even enable the ability to be cut open in the area of the pouring opening, a targeted weakening of the container wall in the form of a scratch or other type of formation of a predetermined breaking point must be provided. This is often the case with film layers containing paper or cardboard, but it can often also be necessary for film composites with multi-layer plastic films. Of course, the formation of predetermined breaking points depends on the type, structure and thickness of the film composite. However, the introduction of predetermined breaking points always has the disadvantage that the plastic closure device has to be positioned very precisely in relation to the tubular bag (or simply in relation to the container with which it is used) during production, because, as a rule, even small deviations from the concentricity of The pouring opening and predetermined breaking point mean that the cutting process is sometimes very difficult or even impossible. This is of course particularly unpleasant when using beverage packaging, because with increasing effort to open it, especially with 'soft' tubular bag-like packaging, splashes naturally occur very easily.

It is therefore the object of the invention to specify an improved plastic closure device for tubular bags made of plastic or a multi-layer plastic film.

This problem is solved by the combination of features of claim 1.

The solution is that in a generic plastic closure device for a tubular bag made of plastic or a multi-layer plastic film, which can be connected to the tubular bag by means of ultrasonic welding and which has an energy introduction arrangement with energy-conducting ribs on a flange underside surface for introducing the ultrasonic energy, a concentration rib is provided on the flange underside surface is, which runs centrically offset to the energy-conducting arrangement and which projects higher than the energy-conducting rib from the flange underside surface and is also arranged immediately adjacent to the pouring opening, the concentration rib extending along a part of the inner circumference of the flange.

It has been found that the introduction of a concentration rib, which runs within the energy-conducting arrangement and which, compared to the energy-conducting rib, protrudes higher from the flange underside surface and is also arranged directly adjacent to the spout opening, is able to combine several advantages at the same time.

On the one hand, it is possible to collect the ultrasonic energy, which is otherwise mostly concentrated in the center of the sonotrode in ring-shaped sonotrodes for ultrasonic welding, thus creating the undesired pinholes, and to divert and focus it to another place of action without undesired side effects. It has been shown that in this way the formation of pinholes can be prevented with great reliability and that the shelf life, in particular of packaging for food, is greatly improved because the tightness of the packaging is ensured.

On the other hand, the redirected and focused ultrasonic energy can also be put to good use at the same time. Because the desired point of action of the diverted ultrasonic energy is now in the immediate vicinity of the concentration rib, the resulting concentration of heat in this area causes a structural and shape change in the plastic or in the multi-layer plastic film of the tubular bag. Because the concentration rib protrudes higher from the underside of the flange than the energy-conducting rib or energy-conducting ribs, greater heating occurs at this point when ultrasonic energy is introduced. As a result, the material of the plastic or the plastic film is softened more locally and flows away from the concentration rib. The material thickness of the plastic or the plastic film is thus reduced at this point. At the same time, after the removal of the sonotrode and after cooling, there is also a structural change in the plastic, which manifests itself as locally increased brittleness or reduced elasticity of the plastic film. Thus, with the introduction of a concentration rib according to the invention, a desired predetermined breaking point is also obtained at the same time. The main advantage is, of course, that the otherwise expensive and quality-reducing additional work steps required for the separate production of a weakened zone in the spout area and the effort for the exact positioning of the plastic closure device in relation to this weakened zone are completely eliminated, because all this can be done in a single work step, namely welding the plastic closure device using ultrasound.

The arrangement according to the invention is particularly advantageous for a plastic closure device which has an opening device with at least one cutting tooth, provided that at least one cutting tooth can be moved in the vicinity of the concentration rib when the plastic closure device is actuated in order to cut open the plastic material or the multi-layer plastic film there. Because the energy-conducting rib is arranged directly adjacent to the spout opening of the spout and the cutting tooth or cutting teeth also move in this vicinity, the cutting forces become effective in a weakened material area, which of course facilitates opening of the plastic closure device.

Furthermore, it is advantageous in many cases if the concentration rib is only partially formed around the pouring opening. In this way, it is possible to prevent or at least make it more difficult for the section, which can be easily removed (because of the weakened area), to fall out of the spout area into the interior of the container. In the case of plastic closure devices with an opening device with one or more cutting teeth, the possibility of positioning the only partially formed concentrating rib along the circumference of the spout opening - and thus also that part of the material that can be easily cut out - can also be used to ensure that the partially cut out piece of material can be removed after the completion of the cutting process comes to rest behind the incisors in such a way that the resulting opening follows of the restoring forces does not automatically (partially) close again.

The concentrating rib itself is advantageously provided with a rounded elevation because contact with the plastic or the multi-layer plastic film material of the tubular bag is linear rather than surface-like, which leads to a higher concentration of ultrasonic energy and thus to higher local heating.

In principle, it should also be noted that the plastic closure device according to the invention is in principle suitable for various types of opening devices (built into the plastic closure device). Although only a single exemplary embodiment with an opening device with a cutting device is shown below, applications with opening devices are also possible in which the plastic or the multi-layer plastic film is pierced, pierced or pulled off.

• 1 die prinzipielle Anordnung einer Kunststoffverschlussvorrichtung und einer Sonotrode bei einem Ultraschallschweissvorgang, die
• 2 eine teilweise Seitenansicht des Unterteils einer erfindungsgemässen Kunststoffverschlussvorrichtung mit einer Öffungsvorrichtung, die
• 3 eine teilweise Schnittansicht des Unterteils der Kunststoffverschlussvorrichtung nach 2, und die
• 4 das Unterteil in einer vereinfachten Ansicht von unten.

The invention will now be described in more detail below using an exemplary embodiment. The

• 1 the basic arrangement of a plastic closure device and a sonotrode in an ultrasonic welding process, the
• 2 a partial side view of the lower part of a plastic closure device according to the invention with an opening device, the
• 3 Figure 12 shows a partial sectional view of the base of the plastic closure device 2 , and the
• 4 the lower part in a simplified view from below.

the 1 shows the basic arrangement of a plastic closure device 1 and a sonotrode 2 for ultrasonic welding in an ultrasonic welding process. For this purpose, the plastic closure device 1 is placed on the casing material 3 (plastic or multilayer plastic film) of the tubular bag at the desired location and then welded to the casing material 3 in the area of a flange 4 . It was already mentioned at the outset that the ultrasonic energy in ring-shaped sonotrodes for ultrasonic welding is sometimes mostly concentrated in a central area Z indicated by arrows and thus leads to the undesired pinholes in this area of the casing material 3 .

the 2 shows a partial side view of a lower part 5 of a plastic closure device 1 according to the invention with an opening device with a cutting device 6 (see 3 ). The plastic closure device 1 comprises at least the lower part 5 with a spout 7, a pouring opening 8 and the flange 4. The pouring opening 8 is of course continuous.

An energy introduction arrangement 10 is arranged on the flange 4 on its flange underside surface 9, which can be connected to the plastic material or the plastic film of the tubular bag, ie the casing material 3 of the tubular bag, by means of ultrasonic welding.

The energy introduction arrangement 10 is arranged concentrically to the spout opening 8 in a peripheral region 11 of the flange 4 and has at least one energy conducting rib 12 .

A concentrating rib 13 is present on the flange underside surface 9 , which runs centrally offset to the energy-conducting arrangement 10 and projects higher from the flange underside surface 9 than the energy-conducting rib 12 and is also arranged directly adjacent to the pouring opening 8 . The concentration rib 13 is therefore surrounded by the energy conduction arrangement 10 .

Furthermore, the lower part 5 has an external thread 14 onto which a closure cap part (not shown), which also belongs to the plastic closure device, is screwed on. Also visible are a retaining bead 15 and a retaining cam 16, which are used to separate a guarantee band (also not shown) belonging to the closure cap part from the closure cap part when it is used for the first time. It is therefore assumed that the plastic closure device 1 shown here with an opening device with a cutting device is basically of a known type in which, when the closure cap part is unscrewed, both the guarantee strip is torn off and the cutting device 6 arranged inside the lower part 5 is set in motion to cut open the casing material 3 of the tubular bag in the area of the pouring opening 8 .

the 3 FIG. 12 shows another partial sectional view of the lower part 5 of the plastic closure device 1 2 . Some details can be seen more clearly here, in particular the arrangement and proportions of the energy introduction arrangement 10 with the energy-conducting rib 12 and the concentration rib 13. It is clear here that the concentration rib 13 is a rounded elevation or at least has a rounded shape. For better understanding, the area of change 17 is also indicated here, in which the concentration rib 13 in the vicinity of the higher tempera tur caused material change of the plastic to increased brittleness takes place. Furthermore, a dividing line 18 is drawn in, which is intended to clarify the area in which the at least one cutting tooth 19 of the cutting device 6 (see 4 ) cuts through the casing material 3 when opening the plastic closure device. The dividing line 18 is thus located in the vicinity of the concentration rib 13 and consequently at least partially in the area of change 17.

Furthermore, in the 3 still a part of an internal thread 20 recognizable with the in the 4 only schematically drawn cutting device 6 combs. When the plastic closure device is opened, the cutting device 6 is forcibly rotated by means of the internal thread 20 and is moved toward the casing material 3 .

the 4 finally shows the lower part 5 in a simplified view from below, i.e. from direction A. It can be clearly seen here that the concentrating rib 13 is arranged directly adjacent to the pouring opening 8 and that the concentrating rib 13 here only partially runs around the pouring opening 8 is formed, namely about three quarters of the circumference. The latter is of course a constructive detail and could also be chosen differently. However, it seems important that the concentration rib 13 extends at least over the greater part of the circumference so that the desired concentration effect of the ultrasonic energy also takes place to a sufficient extent so that the effect of pinhole formation actually no longer occurs.

The cutting device 6 is in the 4 shown only schematically and primarily with regard to their arrangement within the pouring opening 8 . In this specific case, it has a large number of smaller cutting teeth 19, which are arranged at the end of an indicated hollow cylinder. However, this embodiment is only exemplary, because many other construction forms are possible.

Claims (6)

Plastic closure device (1) for a tubular bag made of plastic or a multi-layer plastic film, wherein - the plastic closure device (1) comprises at least one lower part (5) with a spout (7), a spout opening (8) and a flange (4), and wherein - an energy supply arrangement (10) is arranged on the flange (4) on its flange underside (9), which can be connected to the plastic material or the plastic film of the tubular bag by means of ultrasonic welding, and wherein - the energy supply arrangement (10) has at least one concentric to the pouring opening (8) energy-conducting rib (12) arranged in the peripheral region (11) of the flange (4), characterized in that there is a concentration rib (13) on the flange underside surface (9), which is offset centrally to the energy-conducting arrangement (10) and runs opposite the energy-conducting rib ( 12) protrudes higher from the flange underside surface (9) and immediately adjacent to di e pouring opening (8) is arranged, wherein the concentration rib (13) extends along part of the inner circumference of the flange (4). Plastic locking device (1) according to Claim 1 , characterized in that the concentration rib (13) is an elevation rounded in cross-section. Plastic locking device (1) according to Claim 1 or 2 , characterized in that the part of the inner circumference along which the concentration rib (13) extends is at most 330° or preferably 240° to 300°. Plastic closure device (1) according to one of patent claims 1 until 3 , characterized in that the plastic closure device (1) has an opening device with a cutting device (6) with at least one cutting tooth (19), wherein the at least one cutting tooth (19) when the plastic closure device (1) is actuated in the vicinity of the concentration rib (13) is circumferentially movable to cut open the plastic material or the multi-layer plastic film. Plastic locking device (1) according to patent claim 4 , characterized in that the cutting device (6) is arranged and guided in such a way that it only cuts open a partial circle area of the tubular bag which runs at least approximately directly next to the concentration rib (13). Plastic closure device (1) according to one of patent claims 1 until 5 , characterized in that there are also further guide ribs (21) running radially to the at least one energy-conducting rib (12) and running essentially to the periphery of the flange (4).

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