EP1453027B1 - Foil element - Google Patents

Description

The present invention relates to a film element for absorbing tensile forces.

Sheet-like elements are often used to transmit tensile forces in the direction of a longitudinal extent, for example as (in particular self-adhesive) functional parts for carrying, connecting, closing and / or covering objects. Examples from everyday life are adhesive tapes or adhesive tapes. Furthermore, this includes a wide variety of loops, straps and tags, carrier bags or carry handles, load securing films (for example, on loaded pallets), closure labels, seal labels and packaging films.

Especially in the field of medicine, but also for drugstore, so-called ironing labels are used. These have a bow-shaped suspension tab, which can be pulled out of the film plane of the remaining, on a container, such as an infusion bottle, glued label. The container is hung upside down on the hanging strap. The bow-shaped suspension tab is then exposed depending on the size and filling of the container not insignificant tensile loads.

Such ironing labels are for example from the publications DE 39 07 862 A1 . DE 91 01 464 U1 . EP 0 356 574 A2 and EP 0 632 422 A1 known.

In the case of tensile stress on films, microcracks occur, in particular starting from small material defects. At the cracking end, locally elevated stresses act to propagate the crack and ultimately to failure of the material, i. lead to tearing of the film.

Since the contours of iron-on labels are usually produced by punching, the occurrence of microcracks from edge defects, which can result from poor die-cuts, for example due to a worn punch, is possible here. This problem is exacerbated by the considerably more productive rotary punching compared to roller flat punching.

Tearing the hanger tab of a hanger label leads to the falling down of the container suspended therefrom. For infusion bottles, this can have serious consequences for the patient being treated.

In the prior art, film-loaded film members are made by using thicker or more tear-resistant, i. usually much more expensive material designed with certain safety reserves.

Thus, for example, various olefin films are used, which although have a higher tear propagation resistance and thus are less prone to injury, but have a higher elongation and lower tensile strength, which is why very thick films (film thickness about 150-250μm) are used. Furthermore, multilayer film composites are also used. Thus, for example, a combination of two 75 and 50 μm thick layers of PET has a higher security against injuries than single-layered PET with a thickness of 125 μm. Nevertheless, minor injuries in critical areas of a hanger label, for example at the suspension point or at curved punches at the transition of a hanger tab into the affixed area of the label, lead to significantly reduced tensile strengths.

Table 1 shows by way of example the weakening of the strap of a two-ply strap label made of PET by edge injuries. The tensile strength in Newton for the undamaged label as well as for slight edge damage of one of the layers is listed. <b> Table 1: Tensile strength of a two-layered PET strap </ b> unhurt Violation of a situation Injury of both layers Tensile strength [N] 206 50 1.4

As can be easily seen from Table 1, a slight edge damage of a layer already causes a considerable susceptibility to cracking with concomitant reduction in the tensile strength, while an edge injury of both layers can reduce the tensile strength by orders of magnitude.

Table 2 shows the tensile strength in Newtons for the injured and the undamaged condition for 25 mm wide, one- or two-layer film strips of different materials. The materials "A" and "B" are tougher plastic materials of lower extensibility, in the materials "C" and "D" to less tensile plastic materials higher ductility. The pm values indicate the respective thickness of the film or film layers. <b> Table 2: Tensile strength 25 mm wide film strip </ b> material Tensile strength [N] uninjured Tensile strength [N] violated "A" (125 μm) 665 under 300 "A" (75 μm) 437 189 "A" (50 μm) 252 112 "A" (75μm / 50μm) 556 246 (both situations injured) 366 (one position injured) "B" (40μm / 40μm) 199 63 "C" (101 μm) 40 34 "D" (165 μm) 236 167 "D" (60 μm) 77 56

It can be easily seen from Table 2 that, in the case of conventional film strips subjected to tensile loading, a pronounced decrease in the tensile strength in the presence of edge damage is evidently unavoidable.

In view of the described problem, the present invention has the object to provide a film element for receiving tensile forces, which has an increased security against tearing due to cracking. In particular, it is also an object of the present invention to provide a container hanger serving as a hang tag with higher safety reserves, especially for injuries. On the other hand, with the same or higher tear safety compared to conventional technical implementations, the cost of materials should be reduced, or less expensive materials could be used.

According to one aspect of the present invention, this object is achieved by a film element according to claim 1. Particularly advantageous embodiments comprise film elements according to claims 2 to 11.

According to the invention, the loadability or tear resistance of tensile-absorbing film elements, in particular bow-shaped suspension straps, by local weakenings, such as e.g. Longitudinal slots, increased. The weakening zones, i. locally weakened by longitudinal slots or the like. Act as force distribution elements, which derive forces along the weakening in uninjured material regions, or can distribute to a larger force-absorbing surface area. Thus, the locally occurring maximum load is reduced. If cracking occurs, the crack propagates only to the weakening zone, where stress spikes are broken down, as the applied forces split to some extent, thereby reducing the stress on individual material segments. As a result, increases the force required for the crack propagation and the tensile strength of the film element increases.

In particular, the present invention may also serve to provide film elements having a clearly defined tear stop, i. to provide a predetermined crack end. In other words, the invention also includes films which may tear only up to a certain point. Thus, for example, defined tear-film-shaped airbag covers are possible.

Fig. 1a

zeigt dabei die dem Stand der Technik entnommene Grundform eines Bügeletiketts mit Aufhängelasche. Erfindungsgemäße Schwächungszonen sind hier nicht visuell hervorgehoben.

Fig. 1b

zeigt perspektivisch ein auf einen über Kopf aufzuhängenden Behälter aufgeklebtes Bügeletikett der in Fig. 1a dargestellten Grundform.

Fig. 1c

zeigt perspektivisch in Vergößerung einen Ausschnitt der Fig. 1b im strichliert umrandeten Bereich A bei Aufhängung des Behälters über Kopf an der Aufhängelasche.

Fig. 2a

zeigt ein Bügeletikett der in Fig. 1a dargestellten Grundform, bei welchem die Schwächungszonen als Längsschlitze ausgeführt sind.

Fig. 2b

zeigt ein mehrlagiges Bügeletikett der in Fig. 1a dargestellten Grundform, bei welchem die Schwächungszonen als lokale klebstoffreie Bereiche zwischen den Folienlagen ausgeführt sind.

Fig. 2c

zeigt ein Bügeletikett der in Fig. 1a dargestellten Grundform, bei welchem die schraffiert angedeuteten Schwächungszonen als klebeschwache Randbereiche ausgeführt sind.

Fig. 3

zeigt in perspektivischer Ansicht einen Schnitt im strichliert umrandeten Bereich B des in Fig. 2a dargestellten Bügeletiketts.

Fig. 4

zeigt in perspektivischer Ansicht einen Schnitt durch ein weiteres durch Zug belastetes Folienelement, bei welchem die Schwächungszonen als zueinander versetzte Anstanzungen in unterschiedlichen Folienlagen ausgeführt sind.

Fig. 5

zeigt in perspektivischer Ansicht einen Schnitt durch ein weiteres durch Zug belastetes Folienelement, bei welchem die Schwächungszone als Zwischenlage mit niedrigerem E-Modul ausgebildet ist.

Fig. 6

zeigt in perspektivischer Ansicht einen Schnitt im strichliert umrandeten Bereich C des in Fig. 2b dargestellten Bügeletiketts.

Fig. 7

zeigt in perspektivischer Ansicht einen Schnitt im strichliert umrandeten Bereich D des in Fig. 2c dargestellten Bügeletiketts.

Fig. 8

zeigt in perspektivischer Ansicht einen Schnitt im strichliert umrandeten Bereich D des in Fig. 2c dargestellten Bügeletiketts in alternativer Ausführung.

Fig. 9

zeigt ein Diagramm, welches die erhöhte Reißfestigkeit eines erfindungsgemäß geschlitzten gegenüber einem ungeschlitzen Bügeletikett gemäß dem Stand der Technik illustriert.

In the appended drawings, examples of preferred embodiments of the present invention are explained in more detail. The selected representations are included not to scale and purely schematic. In particular, the layer thicknesses are greatly increased in the case of sectional representations for reasons of clarity, and partial gaps between adjoining layers are shown in the manner of an exploded view.

Fig. 1a

shows the state of the art removed basic shape of a hanger label with hanging strap. Weakening zones according to the invention are not visually highlighted here.

Fig. 1b

shows in perspective a glued on a head hanging container label in the Fig. 1a illustrated basic form.

Fig. 1c

shows in perspective in magnification a section of the Fig. 1b in dashed rimmed area A with suspension of the container overhead on the suspension strap.

Fig. 2a

shows a hanger label of in Fig. 1a illustrated basic form in which the weakening zones are designed as longitudinal slots.

Fig. 2b

shows a multi-layer iron-on label of Fig. 1a illustrated basic form in which the weakening zones are designed as local adhesive-free areas between the film layers.

Fig. 2c

shows a hanger label of in Fig. 1a illustrated basic form, in which the hatched indicated weakening zones are designed as adhesive waking edge areas.

Fig. 3

shows a perspective view of a section in the dashed rimmed area B of Fig. 2a illustrated ironing labels.

Fig. 4

shows a perspective view of a section through another loaded by train film element, in which the weakening zones are designed as staggered punching in different layers of film.

Fig. 5

shows a perspective view of a section through another loaded by train foil element, wherein the weakening zone is formed as an intermediate layer with a lower modulus of elasticity.

Fig. 6

shows a perspective view of a section in the dashed rimmed area C of FIG Fig. 2b illustrated ironing labels.

Fig. 7

shows a perspective view of a section in the dashed rimmed area D of in Fig. 2c illustrated ironing labels.

Fig. 8

shows a perspective view of a section in the dashed rimmed area D of in Fig. 2c illustrated ironing labels in an alternative design.

Fig. 9

shows a diagram illustrating the increased tensile strength of a slotted according to the invention over a non-slit strap label according to the prior art.

In Fig. 1a the basic form of an ironing label 1 according to the invention taken from the state of the art is shown with a punched suspension tab 2, weakening zones according to the invention not being visually emphasized here. The end regions 4a, 4b of the punching 5 can be designed differently, in addition to the illustrated variant, advantageous configurations known from the prior art, for example in the form of screws, can also be provided. In Fig. 1b is the ironing label 1 by means of a self-adhesive coating intended adhered to a container 3, which is, for example, an infusion bottle, which is hang upside down. The dashed rimmed area A with suspension of the container overhead on the suspension lug 2 is in Fig. 1c shown enlarged. It is clear that, as in the prior art, the area near the punching 5 on the suspension lug 2 must absorb the majority of the tensile forces F. When executed according to the prior art ironing labels here is the risk of cracking particularly large.

In Fig. 2a is one according to the in Fig. 1a pictured illustrated strap label, which has slots 6a, 6b in the hanging tab 2, which (at intended use) are oriented in the loading direction. The slits 6a, 6b may be made by punching or cutting, and either pass through the film or reduce it in thickness only locally in the manner of a groove.

Fig. 3 shows the dashed bordered area B of in Fig. 2a illustrated strap labels 1 in a perspective sectional view. (Of course, however, other tensile foil elements can be designed accordingly.) Defined as a slot 6a weakening zone is on both sides of the length, ie limited transversely to the direction indicated by the arrows F loading direction in each case by film material 7. Cracking progressing from the edge due to a micro-injury 8 comes to a halt at the latest at slot 6a, since stress peaks are reduced here, and the locally increased stresses are dissipated into less stressed elements of the foil material 7.

Fig. 4 shows a two-layer design in which slots 9a, 9b are arranged offset in the film layers 10a, 10b to each other. The film layers 10a, 10b are connected to one another via an adhesive layer 11. Only for reasons of clarity, the lowermost film layer 10b is shown lifted from the other two layers 10a, 11th The staggered arrangement results in higher safety margins, if the film element in both film layers 10a, 10b should also have an edge injury.

Fig. 5 shows a film element which between the film layers 12a, 12b still has a bonded therewith intermediate layer 13 whose modulus of elasticity is less than the modulus of elasticity of the film layers 12a, 12b, and which thus represents a weakening zone in the context of the invention, the upward and below, ie transverse to the direction indicated by the force arrows F loading direction of the film layers 12a, 12b is limited. With progressive cracking 8 in the upper film layer 12b, the intermediate layer 13 is stretched due to the transmission of force in the adhesive layer 14a. By varying degrees of strain at the top and bottom of the relatively soft intermediate layer 13 (indicated by the double arrows of different length) is locally reduced stress, and the crack does not transfer on the adhesive layer 14b on the lower film layer 12b.

The FIGS. 2b and 6 show a locally discontinuous adhesive layer 11 for decoupling an upper 12a from a lower foil layer 12b. Here, the adhesive-free recesses 15a, 15b weakening zones in the context of the present invention. As related to Fig. 5 explains, so the crack transfer from one to the other film layer 12a, 12b avoided. In addition, by stress dissipation of the Rissfortsetzung counteracted when a resulting in a film layer 12a, 12b crack reaches the weakening zone 15a. Only for reasons of clarity, the uppermost film layer 12a is shown lifted from the other two layers 11, 12b.

The Figures 2c . 7 and 8 show a locally weakened adhesive layer 11 for decoupling an upper 12a from a lower foil layer 12b. The weakening zones according to the invention, their location in Fig. 2c indicated by hatching, here in a local, up and down by the unattenuated film layers 12a, 12b limited weakening of the adhesive layer 11. It is particularly favorable here that the weakening zones in particularly vulnerable edge areas, ie here in the near-round rounding of the punching 5th are arranged. According to the in Fig. 7 the alternative shown is the weakening in a locally less adhesive or less viscous or less strongly crosslinked adhesive 16. In the in Fig. 8 the alternative shown is the weakening in a locally provided adhesive-repellent coating 17 of the lower layer 12b. This may be, for example, a siliconization. Again for reasons of clarity is in Fig. 7 the upper film layer 12a and in Fig. 8 the lower film layer 12b including adhesive-repellent coating 17 is shown lifted off the rest of the film composite. A possible embodiment is also a local adhesive neutralization.

It goes without saying that the embodiments of the weakened zones illustrated by means of the examples can also be combined with one another.

The effectiveness of the measures according to the invention for increasing the tensile strength is based on the bar graph in FIG Fig. 9 clarified. Plotted here is the tensile strength Fmax in Newton for PET / polyolefin film composites of different layer thicknesses. These are ironing labels 1, which in the end region 4a, 4b of the the suspension tab 2 defining punching 5 are helical. The left, lighter beam represents the tensile strength of an unslotted version according to the prior art, the respective right, darker bars the tensile strength at slitting the heavily loaded lower layer in the snail-shaped punching, the longitudinal slit of the tensile load in normal use is aligned. The four pairs of bars represent composites with different layer thicknesses of the individual film layers. The higher load capacity of the slotted embodiments according to the invention is clearly visible.

In the illustrated experiment, the bracket in the helical area were injured by a cut. □ The weakening zones according to the invention in the form of a slit here empirically verifiable increase the tensile strength and thus the product safety of the ironing label with otherwise the same material structure. In the case of an undesired injury in practice, e.g. can not be excluded due to worn punching, the inventive measure of introducing a weakening zone pays off particularly.

The tear properties can also be varied by adjusting the parameters material composition, material thicknesses, material types, degree of stretching, pigmentation, surface treatment. Thus, the following materials are particularly suitable for two- or multi-layer composites: polyethylene terephthalate (for upper and / or lower layer), polyolefins (for upper and / or lower layer), polyamides (for upper and / or lower layer), polypropylene ( for upper layer), oriented polypropylene (for upper and / or lower layer), polybutylene terephthalate (for upper layer), nonwovens (for upper layer), lattice structures.

Claims (11)

1. A foil element (1) in the form of a hanger-type label, comprising at least one foil layer (10a, 10b) including a hanger flap (2) which is delimited by a punched pattern (5) and in the bonded state of the hanger-type label (1) can be pivoted and/or pulled out of the remaining face of the hanger-type label, for instance for hanging up an infusion bottle on which the hanger-type label (1) can be applied by gluing, the hanger flap (2) comprising a zone which takes up a major part of tensile forces (F) with intended use, characterized in that the foil element (1) - in at least one zone (A, B, C, D) which is prone to tearing when loaded - comprises at least one weakening zone (6a, 6b, 9a, 9b, 13, 15a, 15b, 16) which extends along the direction of application of the tensile forces (F), reduces stress peaks when loaded and is bordered at both sides by non-weakened material (7, 10a, 10b, 12a, 12b) in at least one direction transverse to the direction of application of the tensile forces (F), the weakening zone comprising at least one longitudinal slot (6a, 6b, 9a, 9b) penetrating only one foil layer (10a, 10b) in each case.
2. The foil element according to claim 1, characterized in that the foil layers (10a, 10b, 12a, 12b) are glued, welded or sealed to each other at least in part.
3. The foil element according to any of the claims 1 or 2, characterized in that the foil element comprises several mutually offset longitudinal slots (9a, 9b) in different foil layers (10a, 10b).
4. The foil element according to any of the claims 1 to 3, characterized in that at least one weakening zone comprises a separating aid (13, 15a, 15b, 16, 17) which is able to effect the local, at least partial force-related decoupling of two adjoining foil layers (12a, 12b).
5. The foil element according to claim 4, characterized in that the foil element (1) comprises at least one full-area or partial adhesive layer (11) which connects two foil layers (10a, 10b, 12a, 12b) to each other, and in that the separating aid is realized as a means (13, 15a, 15b, 16, 17) for locally lowering the adhesive force between the foil layers (12a, 12b).
6. The foil element according to claim 5, characterized in that the means for locally reducing the adhesive force comprise at least one of the following means:

   - a local disruption (15a, 15b) of the adhesive layer (11),

   - a locally lower curing grade of the adhesive layer (11),

   - within the adhesive layer (11), a local arrangement of an adhesive agent (16) which has a smaller areal adhesive force than the surrounding adhesive layer (11),

   - a locally introduced neutralization of the adhesive,

   - a surface area (17), treated so as to locally lower the adhesive force, of at least one foil layer (12b) adjoining the adhesive layer (11).
7. The foil element according to claim 4, characterized in that the separating aid is realized as an intermediate layer (13) having a higher degree of extensibility.
8. The foil element according to any of the preceding claims, characterized in that the foil element (1) has its underside at least partially provided with a self-adhesive coating.
9. The foil element according to any of the claims 1 to 8, characterized in that the foil element is realized as a carrying handle.
10. The foil element according to any of the claims 1 to 9, characterized in that the foil element is realized as a cargo securing foil.
11. The foil element according to claim 8, characterized in that it is realized as an adhesive strip.

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