EP1453027A2 - Foil element - Google Patents

Abstract

Foil element for absorbing tensile forces (F) comprises in at least one region at risk of tearing under loading at least one weakened zone (6a) reducing local tension peaks under loading and extending in the contact direction of the tensile forces. The weakened zone is defined on both sides by non-weakened material (7) in at least one direction perpendicular to the contact direction of the tensile forces. Preferred Features: The foil element has at least two foil layers at least partly glued, welded or sealed together. At least one weakened zone is a slit passing through only one foil layer.

Description

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

Foil-shaped elements are often used to pull tensile forces towards one Transfer longitudinal expansion, for example as (in particular self-adhesive) Functional parts for carrying, connecting, closing and / or covering Objects. Examples from everyday life are tapes or tapes. Further include a wide variety of loops, ribbons and pendants, carrier bags or Carrying bag handles, load securing films (e.g. over loaded ones Pallets), sealing labels, sealing labels and packaging films.

Especially in the field of medicine, but also for drugstores so-called strap labels used. These have a bow-shaped hanging tab on which is from the film level of the rest, on a container, for example pull out an infusion bottle with the label stuck on it. On the hanging tab the container is hung upside down. The bow-shaped hanging tab is then each tensile loads not insignificant according to the size and filling of the container exposed.

Such iron-on 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 is known.

When foils are subjected to tensile stress, they start in particular from small ones Material defects micro cracks. At the end of the crack there are locally increased tensions which lead to the propagation of the crack and ultimately to the failure of the material, i.e. cause the film to tear.

Since the contours of iron-on labels are usually made by punching, here is the occurrence of microcracks starting from edge defects, which from bad punching, for example due to a worn punch, can result possible. In the case of the much more productive compared to flat roller punching Rotational punching exacerbates this problem.

Tearing off the hanging tab of an ironing label leads to it falling off suspended container. With infusion bottles, this can have serious ramifications for the treated patient.

According to the state of the art, film parts that are subjected to tension are pulled through Use thicker or more tear-resistant, i.e. usually much more expensive Materials designed with certain safety reserves.

For example, various olefin films are used, which are higher Have tear resistance and are therefore less prone to injury, however, have a higher elongation and lower tensile strength, which is why thick foils (foil thickness approx. 150-250µm) can be used. Furthermore, too multilayer film composites used. For example, a network of two 75 and 50 µm thick layers of PET are more secure against injuries than single-layer PET with a thickness of 125 µm. Even so, minor injuries result in critical areas of an iron-on label, such as at the point of suspension or on curved ones Punchings at the transition of a hanging tab into the glued area of the label, to significantly reduced tensile strengths.

Table 1 shows an example of the weakening of the bracket of a two-layer bracket label made of PET due to edge injuries. The tensile strength is listed in Newtons for the uninjured label and one of the layers in the event of slight edge damage. Tensile strength of a two-layer PET bracket unhurt Violation of a situation Injury to both layers Tensile strength [N] 206 50 1.4

As can be seen in Table 1, there is a slight edge injury a location is already susceptible to cracking with a concomitant reduction in Tensile strength while an edge injury to both layers around the tensile strength Orders of magnitude decrease.

Table 2 shows the tensile strength in Newtons for the injured and the uninjured state for 25 mm wide, one- or two-ply film strips of different materials. The materials "A" and "B" are tensile plastic materials of lower ductility, the materials "C" and "D" are less tensile plastic materials of higher ductility. The pm values indicate the respective thickness of the film or the film layers. Tensile strength 25 mm wide film strips 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 positions injured) 366 (one position violated) "B" (40µm / 40µm) 199 63 "C" (101 µm) 40 34 "D" (165 µm) 236 167 "D" (60 µm) 77 56

Table 2 is easy to see that in conventional with tensile load acted upon film strips a strong decrease in tensile strength when present an edge injury is obviously inevitable.

In view of the problems outlined, the present invention has the object based on creating a film element for absorbing tensile forces, which a has increased security against tearing due to cracking. In particular it is also an object of the present invention, a container hanging device serving label with higher security reserves, especially in the case of injuries to accomplish. On the other hand, with the same or higher tear resistance compared conventional technical implementations reduce the cost of materials, or cheaper materials can be used.

According to one aspect of the present invention, this object is achieved by a Film element according to claim 1 solved. Particularly advantageous embodiments comprise film elements according to claims 2 to 15.

According to the invention, the method is completely surprising for the person skilled in the art Resilience or tear resistance of film elements absorbing tensile forces, in particular bow-shaped suspension brackets, due to local weakening, e.g. Longitudinal slots, increased. The weakening zones, i.e. locally through longitudinal slots or the like weakened areas act as force distribution elements, which forces along the Derive weakening in undamaged material regions, or to a larger one can distribute force-absorbing surface area. Thus the locally occurring Maximum load reduced. In the case of crack formation, the crack only spreads up to that Weakening zone from where voltage peaks are reduced, since the acting To a certain extent split forces, which puts stress on individual material segments is reduced. As a result, the crack propagation required increases Exertion of force, and the tensile strength of the film element increases.

The present invention can in particular also serve to use film elements a clearly defined tear stop, i.e. a predetermined crack end provide. In other words, the invention also includes foils which are only up to allowed to tear down to a certain point. For example, are defined tearing foil-shaped airbag covers 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.

Examples of preferred embodiments of the present invention are explained in more detail with reference to the accompanying drawings. The representations chosen are not to scale and are to be understood purely schematically. In particular, in the case of sectional representations, the layer thicknesses have been greatly increased for reasons of clarity, and gaps between adjacent layers have been shown in the manner of an exploded drawing.

Fig. 1a

shows the basic form of an iron-on label with a hanging tab taken from the prior art. Attenuation zones according to the invention are not visually emphasized here.

Fig. 1b

shows a perspective view of a bracket label of the basic form shown in FIG.

Fig. 1c

shows a perspective enlargement of a section of FIG. 1b in the area A with dashed lines when the container is suspended overhead from the hanging tab.

Fig. 2a

shows a bracket label of the basic form shown in Fig. 1a, in which the weakening zones are designed as longitudinal slots.

Fig. 2b

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

Fig. 2c

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

Fig. 3

shows a perspective view of a section in the dotted area B of the hanger label shown in Fig. 2a.

Fig. 4

shows a perspective view of a section through a further film element loaded by tension, in which the weakening zones are designed as offset punchings in different film layers.

Fig. 5

shows a perspective view of a section through another film element loaded by tension, in which the weakening zone is designed as an intermediate layer with a lower modulus of elasticity.

Fig. 6

shows a perspective view of a section in the dotted area C of the hanger label shown in Fig. 2b.

Fig. 7

shows a perspective view of a section in the dotted area D of the hanger label shown in Fig. 2c.

Fig. 8

shows a perspective view of a section in the dotted area D of the bracket label shown in Fig. 2c in an alternative embodiment.

Fig. 9

shows a diagram illustrating the increased tear strength of a slit under the invention compared to an unslit ironing label according to the prior art.

In Fig. 1a is the basic form of an inventive according to the prior art Ironing labels 1 shown with punched hanging tab 2, wherein weakening zones according to the invention are not visually highlighted here. The End regions 4a, 4b of the punching 5 can be designed differently, in addition to the illustrated variant can also advantageous known from the prior art Designs, for example in the form of a screw, can be provided. In Fig. 1b that is Iron-on label 1 as intended by means of a self-adhesive coating glued on a container 3, which is, for example, a Infusion bottle deals, which is to be hung upside down. The one with a dashed border Area A when hanging the container upside down on the hanging tab 2 is in Fig. 1c shown enlarged. It becomes clear that, as in the prior art, the Area near the punch 5 on the hanging tab 2 the majority of the tensile forces F must record. In the case of iron-on labels designed according to the prior art, this is here the risk of cracking is also particularly great.

In Fig. 2a is a bracket label designed according to the basic shape shown in Fig. 1a mapped, which has slots 6a, 6b in the hanging bracket 2, which (at intended use) are oriented in the direction of loading. The slots 6a, 6b can be made by punching or cutting, and either by Go through the film or film layer or just locally in the manner of a groove reduce their thickness.

FIG. 3 shows the region B outlined in dashed lines of that shown in FIG. 2a Ironing labels 1 in a perspective sectional view. (Of course you can but also other tensile foil elements must be designed accordingly.) The as Slit zone 6a is lengthwise on both sides, i.e. across to the direction of loading indicated by the arrows F in each case by foil material 7 limited. Crack formation progressing from the edge due to a micro-injury 8 comes to a stop at slot 6a at the latest, since voltage peaks are reduced here be, and the locally increased tensions in less stressed elements of the Foil material 7 are derived.

Fig. 4 shows a two-layer design, in which slots 9a, 9b in the film layers 10a, 10b are arranged offset to one another. The film layers 10a, 10b are over a Adhesive layer 11 bonded together. Is only for reasons of clarity the bottom film layer 10b lifted off from the two further layers 10a, 11 shown. The staggered arrangement results in higher safety reserves, if the film element in both film layers 10a, 10b at the same time an edge injury should have.

FIG. 5 shows a film element which has another between the film layers 12a, 12b with this glued intermediate layer 13, the modulus of elasticity is lower as the modulus of elasticity of the film layers 12a, 12b, and which thus a weakening zone in Represents the meaning of the invention, the up and down, i.e. across to the Force arrows F indicated loading direction limited by the film layers 12a, 12b is. As crack formation 8 progresses in the upper film layer 12b, the Intermediate layer 13 stretched due to the power transmission in the adhesive layer 14a. Due to different degrees of stretch on the top and bottom of the relatively soft Liner 13 (indicated by the different length double arrows) is local Stress is released and the crack does not transfer through the adhesive layer 14b continue on the lower film layer 12b.

FIGS. 2b and 6 show a locally interrupted adhesive layer 11 Decoupling an upper 12a from a lower film layer 12b. Here are the Adhesive-free recesses 15a, 15b weakening zones in the sense of the present Invention. As explained in connection with Fig. 5, the crack transmission avoided from one to the other film layer 12a, 12b. In addition, through Stress dissipation of the crack continuation counteracted when one in a foil layer 12a, 12b created crack reaches the weakened zone 15a. Just out For reasons of clarity, the top film layer 12a is lifted off the two further layers 11, 12b are shown.

FIGS. 2c, 7 and 8 show a locally weakened adhesive layer 11 Decoupling an upper 12a from a lower film layer 12b. The Attenuation zones according to the invention, their position in FIG. 2c by hatching is indicated here consist of a local, up and down by the weakened film layers 12a, 12b limited weakening of the adhesive layer 11. It is particularly favorable here that the weakening zones are particularly at risk Marginal areas, i.e. are arranged here in the near-round curve of the punch 5. According to the alternative shown in FIG. 7, the weakening is local less adhesive or less viscous or less cross-linked Adhesive 16. In the alternative shown in Fig. 8, the weakening is in a locally provided adhesive-repellent coating 17 of the lower layer 12b. This can be siliconization, for example. Again out For reasons of clarity, the upper film layer 12a in FIG. 7 and the upper one in FIG. 8 lower film layer 12b including adhesive-repellent coating 17 each from rest of the film composite shown. Another possible implementation is also local adhesive neutralization.

It goes without saying that the explanations given using the examples of the weakening zones can also be combined with one another.

The effectiveness of the measures according to the invention for increasing the tear strength is illustrated using the bar diagram in FIG. 9. It is applied here for PET / polyolefin film composites different layer thicknesses the tensile strength Fmax in Newton. These are iron-on labels 1, which in the end region 4a, 4b the punching 5 defining the suspension bracket 2 are helical. The the left, lighter bars represent the tensile strength of an unslit version according to the prior art, the right, darker bar Tensile strength when slotting the particularly stressed lower layer in the area of helical punching, the slitting in the longitudinal direction of the tensile load is aligned when used as intended. The four pairs of bars stand for Composites with different layer thicknesses of the individual foil layers. The higher one Resilience of the slotted designs according to the invention is clear recognizable.

In the experiment shown, the stirrups in the helical area were cut through hurt a cut. □ The weakening zones according to the invention in the form of a Slitting increases the tensile strength and thus the empirically understandable Product safety of the iron-on label with otherwise the same material structure. At a undesirable injury in practice, e.g. due to worn punches cannot be excluded, the measure according to the invention pays off Introducing a weakening zone especially.

The tear properties can also be varied by appropriate adjustment the parameters material structure, material thicknesses, material types, degree of stretching, Pigmentation, surface treatment. So are especially for two or multilayer composites particularly suitable for the following materials: Polyethylene terephthalate (for top and / or bottom layer), polyolefins (for top and / or lower layer), polyamides (for upper and / or lower layer), polypropylene (for top layer), oriented polypropylene (for top and / or bottom layer), Polybutylene terephthalate (for top layer), nonwovens (for top layer), lattice structures.

Claims (15)

Foil element (1) for absorbing tensile forces,
characterized in that the film element (1) in at least one area (A, B, C, D) prone to cracking under load, at least one weakening zone (6a, 6b, 9a) which extends in the direction of the tensile forces (F) and reduces local stress peaks under load 9b, 13, 15a, 15b, 16) which is delimited on both sides by at least one weakened material (7, 10a, 10b, 12a, 12b) in at least one direction transverse to the direction of attack of the tensile forces (F). Film element according to claim 1, characterized in that the film element (1) has at least two film layers (10a, 10b, 12a, 12b). Film element according to claim 2, characterized in that the film layers (10a, 10b, 12a, 12b) are at least partially glued, welded or sealed together. Film element according to one of the preceding claims, characterized in that at least one weakening zone has a longitudinal slot (6a, 6b, 9a, 9b). Film element according to claim 4, characterized in that the longitudinal slot (9a, 9b) only passes through one film layer (10a, 10b). Film element according to claim 5, characterized in that the film element has a plurality of longitudinal slots (9a, 9b) offset from one another in different film layers (10a, 10b). Film element according to one of claims 2-6, characterized in that at least one weakening zone has a separating aid (13, 15a, 15b, 16, 17) which can bring about the local, at least partially force-dependent decoupling of two adjacent film layers (12a, 12b). Film element according to claim 7, characterized in that the film element (1) has at least one full or partial surface adhesive layer (11) which connects two film layers (10a, 10b, 12a, 12b) and that the separating aid as means (13, 15a , 15b, 16, 17) for locally reducing the adhesive force between the film layers (12a, 12b). Film element according to claim 8, characterized in that the means for locally reducing the adhesive force comprise at least one of the following means: local interruption (15a, 15b) of the adhesive layer (11), locally less crosslinking of the adhesive layer (11) within the adhesive layer (11) local arrangement of an adhesive (16) with a lower area-related adhesive strength than the surrounding adhesive layer 811), locally introduced adhesive neutralization, locally treated surface (17) which reduces adhesive strength, at least one film layer (12b) adjoining the adhesive layer (11). Foil element according to claim 7, characterized in that the separating aid is designed as an intermediate layer (13) of higher elasticity. Film element according to one of the preceding claims, characterized in that the film element (1) is at least partially self-adhesive coated on its underside. Film element according to claim 10, characterized in that the film element is designed as a hanger label (1), for example for hanging infusion bottles, which is delimited by a punch (5) and in the glued-on state of the hanger label (1) from the remaining surface of the hanger label has a swing-out and / or pull-out hanging flap (2), for example for hanging up an infusion bottle (3) onto which the hanger label (1) can be stuck. Film element according to one of claims 1-11, characterized in that the film element is designed as a handle. Film element according to one of claims 1-11, characterized in that the film element is designed as a load securing film. Film element according to claim 11, characterized in that it is designed as an adhesive strip.

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