ES3014034T3 - Tear-open strip for a package, method for producing a tear-open strip and package - Google Patents

Abstract

The invention relates to a tear-off strip (10) for a packaging (28), comprising a layer system (12) with a paper substrate (14) and an adhesive layer (16) arranged on a first side of the paper substrate (14). The adhesive layer (16) has, at least in some areas, an irregular surface structure with relative elevations (20) and relative depressions (22). The invention also relates to a method for producing said tear-off strip (10). (Automatic translation with Google Translate, no legal value)

Description

DESCRIPTION

Tear-off strip for packaging, method for producing a tear-off strip and packaging

[0001] The present invention relates to a tear-off strip for packaging, a method for producing said tear-off strip and a packaging with said tear-off strip.

[0002] Tear-off strips for packaging are known from the prior art and are used to facilitate the opening of sealed packages. However, currently, tear-off strips are primarily made of plastic, which is problematic for environmental and recycling reasons. Initial attempts have therefore already been made to produce compostable or biodegradable tear-off strips based on paper.

[0003] In the state of the art, a paper-based tear-off strip is described in document US 1943538 A.

[0004] However, the disadvantage of these paper-based tear strips is that they have a much worse tearing behavior than the previous plastic-based tear strips, since the paper-based tear strips often come off when they are opened and do not open the packaging or only partially open it.

[0005] Therefore, the objective of the present invention is to provide a paper-based tear strip with improved tearing behavior. Another objective is to provide a method for producing such a tear strip. Finally, another objective is to provide packaging with such a tear strip.

[0006] The objectives are achieved according to the invention through a tear-off strip with the features of claim 1, a method for producing said tear-off strip with the features of claim 9 and through a packaging according to claim 15. Advantageous embodiments with convenient improvements are described in the dependent claims, where the advantageous embodiments of each aspect of the invention are to be considered advantageous embodiments of the other aspects of the invention.

[0007] A first aspect of the invention relates to a tear-off strip for packaging comprising a layer system having a paper substrate and an adhesive layer arranged on a first side of the paper substrate. According to the invention, improved tearing behavior is achieved because the adhesive layer has, at least in regions, an irregular surface structure with relative elevations and relative depressions. In other words, according to the invention, a tear-off strip based on paper is provided, the adhesive layer having an irregular surface structure with relative elevations ("heights") and relative depressions (valleys, cells) in regions or completely. Without wishing to be bound by this theory, the inventors assume that the improved tearing behavior is achieved by this irregular surface structure, as it allows the tear strip to adhere locally to varying degrees to an assigned packaging. The depressions or valleys lead to a local weakening of the adhesion, while the elevations or heights lead to a deeper cohesive bond and thus stronger adhesion. When the packaging is opened, the local weakening of the adhesive bond prevents the paper-based tear strip from adhering too strongly and breaking. At the same time, the elevations reliably prevent the overall adhesion to the assigned packaging from becoming too weak. Preferably, the adhesive layer has between 20 and 100 elevations per square centimeter of paper substrate. Particularly preferred are between 40 and 60, in particular approximately 50, elevations per square centimeter. The adhesive layer may essentially consist of one or more suitable adhesives and, where appropriate, may contain additives. For example, a poly(meth)acrylate-based adhesive, a natural or synthetic rubber, and/or a sealing wax can be used. In general, "one" in the context of this disclosure should be understood as indefinite articles, i.e., always also as "at least one," unless explicitly stated otherwise. Conversely, "one" can also be understood as "only one."

[0008] In an advantageous embodiment of the invention, it is provided that the paper substrate is compostable and/or biodegradable. This achieves a better environmental balance. Alternatively or additionally, it is provided that the paper substrate has a grammage between 80 g/m2 and 200 g/m2, in particular between 100 g/m2 and 140 g/m2, in particular approximately 120 g/m2. This ensures sufficient stability of the paper substrate and thus advantageous sealing and tearing behavior of the tear strip for most applications and embodiments. Particularly preferably, the application rate of the adhesive per unit area of the paper substrate is chosen as a dependence or function of the grammage of the paper substrate, with higher application rates per unit area generally being chosen for higher grammages. In this way, on the one hand, a reliable closure of a package can be guaranteed, and on the other hand, reliable tearing behavior can be guaranteed without the tear strip being torn off or ripped prematurely. Alternatively or additionally, advantageous sealing and tearing behavior of the tear strip is guaranteed because the paper substrate has a stability of at least 75 N/15 mm, preferably at least 110 N/15 mm, and/or a thickness between 100 |_im and 250 |_im, in particular between 150 |_im and 200 |_im, in a main extension direction. The main extension direction refers to the direction of the longest extension of the tear strip, i.e., generally the length along which the tearing of the assigned packaging takes place.

[0009] Further advantages result from the fact that the first and/or a second side of the paper substrate are embossed and/or bleached and/or colored and/or printed. In this way, it is particularly easy to adapt the tear-off strip visually and/or functionally to different requirement profiles. For example, an embossed paper substrate can provide an improved release property of the non-adhesive second side.

[0010] In another advantageous embodiment of the invention, it is provided that the adhesive layer is applied to the first side over the entire surface or in regions. In other words, it is provided that the entire surface of the paper substrate is provided with the adhesive layer or only one or more areas of the surface. In this way, the adhesion and tearing behavior can be controlled. An advantageous tearing behavior is alternatively or additionally achieved in that the adhesive layer has an application weight between 15 g/m2 and 60 g/m2, in particular between 20 g/m2 and 30 g/m2. In another embodiment, a particularly uniform tearing behavior is achieved in that the adhesive layer has a regular surface structure, in particular a dot structure and/or a wave structure and/or a line structure and/or a pyramidal structure and/or a truncated pyramidal structure and/or a hexagonal structure and/or a line structure with cells and/or a structure with calottes. Thus, the elevations and depressions of the surface structure present regularly arranged structural elements, where only one type of structural element or two or more types of structural elements may be provided. In the case of several types of structural elements, these may generally have the same or different volumes.

[0011] A further improved tearing behavior results from the fact that the surface structure of the adhesive layer has, at least in regions, a periodic structural element, where at least one extension vector of the periodicity of the structural element is preferably arranged obliquely to the main direction of extension of the paper substrate. In other words, it is provided that the extension vector of the periodicity of the structural element is not arranged parallel or coaxial, but in an unequal angular position 0° or 180° with respect to the main direction of extension of the paper substrate. When the tear-off strip is torn, the forces that are generated are advantageously deflected and distributed better, which particularly reliably prevents the tear-off strip from being torn off.

[0012] In another advantageous embodiment of the invention, a release layer is arranged on the second side of the paper substrate over the entire surface or in regions, the application weight of the release layer being preferably between 0.1 g/m2 and 2.0 g/m2, in particular between 0.2 g/m2 and 1.0 g/m2. In this way, the tear-off strip can be reliably prevented from clogging or sticking to itself, for example, when wound up. The release layer can be based on silicone, where in principle further release layers based on polyacrylate, carbamate, polyvinyl ether wax or other suitable compounds, as well as mixtures thereof, can also be provided.

[0013] Alternatively or additionally, it has proven advantageous to arrange a release strip on one side of the adhesive layer facing away from the paper substrate. This also represents a way of preventing the tear-off strip from blocking or sticking to itself or to unintended areas of an assigned packaging. The release strip can be, for example, a release film or a release paper, for example, silicone paper.

[0014] In another embodiment, advantageous storage or advantageous transport of the tear-off strip wound on a reel is achieved with a preferably transverse winding and/or manufactured as a flat reel.

[0015] A second aspect of the invention relates to a method for producing a tear-off strip for packaging, wherein a layer system is produced by applying an adhesive layer to a first side of a paper substrate. According to the invention, improved tearing behavior is achieved because the adhesive layer is manufactured, at least in regions, with an irregular surface structure with relative elevations and relative depressions. The resulting advantages can be found in the descriptions of the first aspect of the invention, where advantageous embodiments of the first aspect of the invention are to be considered advantageous embodiments of the second aspect of the invention. Conversely, advantageous embodiments of the second aspect of the invention are also to be considered advantageous embodiments of the first aspect of the invention. After production, the tear-off strip can be wound onto reels with cross-winding, which allows a run length of up to 40,000 m or more, typically 10,000 - 20,000 m. Alternatively, the tear-off strip can also be manufactured as a flat reel.

[0016] In an advantageous embodiment of the invention, it is provided that the paper substrate is provided with an irregular surface structure before applying the adhesive layer and/or that the irregular surface structure is produced in the adhesive layer. In general, the irregular surface structure of the adhesive layer can be achieved by applying the adhesive layer itself irregularly to a paper substrate with an at least partially regular surface. However, alternatively or additionally, it can also be provided that the paper substrate is first provided, at least in areas, with an irregular surface, after which the adhesive layer is applied regularly or irregularly to the paper substrate. In principle, the first side and/or the second side of the paper substrate can have an irregular surface. In general, a smooth paper substrate is easier to coat than a rough or structured one.

[0017] In another advantageous embodiment of the invention, it is provided that the adhesive layer is applied to the paper substrate by means of an anilox roller, in particular a tri-helical roller. This allows the adhesive layer to be applied to the paper substrate with a defined local dosage of the adhesive, and thus to create a defined surface structure with predetermined elevations and depressions. In addition to the geometry of the structural element(s) forming the surface structure, the local application volume of the adhesive layer can also be precisely controlled by appropriately selecting the cells or elevations of the anilox roller.

[0018] Further advantages result from the fact that the paper substrate is provided on a second side with a printing layer and/or a release layer. With the help of the printing layer, the visual appearance of the tear-off strip can be adjusted. Furthermore, the tear-off strip can be provided with symbols or instructions for use. In general, printing can be carried out by gravure, flexography, offset, laser, inkjet, or another suitable printing method. The printing ink can be based on nitrocellulose (NC), polyurethane (PU), polyvinyl chloride (PVC), polyvinyl butyral (PVB), or other binders. The release layer prevents the tear-off strip from sticking unintentionally, for example, to itself.

[0019] It has also been shown that it is advantageous to apply a lacquer layer between the printing layer and the separation layer, since in this way the printing layer can be particularly easily protected against damage and, if necessary, given an additionally improved visual appearance.

[0020] By cutting the tear-off strip into several strips, preferably by scissor cutting, the width of the tear-off strip can be adapted to different application purposes, whereby the tear-off strip can initially be produced in a multiple of this width, which facilitates the coating process(es) for forming the layer system. Preferably, after cutting, the tear-off strip has a width of between 2 mm and 15 mm, in particular between 4 mm and 8 mm.

[0021] A third aspect of the invention relates to a packaging, comprising at least one tear-off strip, which is formed according to the first aspect of the invention and/or produced by a method according to the second aspect of the invention. The resulting advantages can be found in the descriptions of the first and second aspects of the invention, where advantageous embodiments of the first and second aspects of the invention are to be considered advantageous embodiments of the third aspect of the invention. Conversely, advantageous embodiments of the third aspect of the invention are also to be considered advantageous embodiments of the first and second aspects of the invention. Preferably, the packaging can be formed in a completely compostable or biodegradable manner. Furthermore, the packaging may comprise two or more tear-off strips.

[0022] With this they show:

Fig. 1 a schematic cross-section through a tear-off strip according to the invention;

Fig. 2 a schematic and partial view of the tear-off strip according to the invention during the application of an adhesive layer;

Fig. 3 a schematic perspective view of a coil of the tear-off strip;

Fig. 4 a top view of a packaging, on which the tear-off strip is arranged; and

Fig. 5 an enlarged view of detail V shown in Fig. 4.

[0023] Fig. 1 shows a schematic cross-section through a tear-off strip 10 according to the invention. The tear-off strip 10 comprises a layer system 12, which in the present case has a paper substrate 14, an adhesive layer 16 arranged on a first side of the paper substrate 14 and a separating layer 18, in principle optional, arranged on the second side of the paper substrate 14. It can be seen in the cross-section that the adhesive layer 16 has an irregular surface structure with a wave structure of relative elevations 20 and relative depressions 22.

[0024] The tear-off strip 10 shown is compostable and/or biodegradable. In general, the paper substrate 14 is formed from cellulose. However, other types of paper can also be provided, for example, paper based on PET fibers. The grammage of the paper substrate 14 is between 90 and 200 g/m2, for example 120 g/m2. The paper substrate 14 can be white or bleached, or unbleached or colored. It can also be provided that the paper substrate 14 is printed on one or both sides. The paper substrate 14 has a high mechanical stability in the main direction of extension H (see Fig. 2) or running direction of at least 75 N/15 mm, in particular at least 110 N/15 mm or more. As can be seen in Fig. 1, the paper substrate 14 is smooth to allow good coatability. In principle, it can also be provided that the paper substrate 14 has a structured surface on its first and/or second side, onto which the adhesive layer 16 and/or the release layer 18 is applied. By embossing the paper substrate 14, a better release property of the non-adhesive second side can often be achieved.

[0025] In the present case, the adhesive layer 16 is applied over the entire surface of the first side of the paper substrate 14, where basically only one application per area can also be provided. As can be seen in FIG. 2, which shows a schematic and partial view of the tear-off strip 10 according to the invention during application of the adhesive layer 16, the structured surface of the adhesive layer 16 has a regular line or wave structure, which is formed by the lines or waves formed by the elevations 20 as structural elements. The shown line or wave structure can be produced, for example, by a corresponding engraving of a coating cylinder, for example, by means of a tri-helical roller. Furthermore, it can be seen in FIG. 2, that the line structure with the elevations 20 and depressions 22 is formed regularly, since the lines are periodically repeated on the surface of the paper substrate 14. In addition, an extension vector V of the periodicity of the line structure element is arranged obliquely to the main extension direction H of the paper substrate 14. In other words, the lines or elevations 20 do not run perpendicularly or parallel to the main extension direction H, but rather run diagonally. In principle, other regular or irregular surface structures (patterns) can also be produced instead of line or wave surface structures.

[0026] For the adhesive layer 16, an adhesive based on polyacrylate, natural or synthetic rubber, or a sealing wax may be used. The application of the adhesive is usually between 15 and 60 g/m2, in particular between 20 and 30 g/m2.

[0027] The release layer 18 can also be applied over the entire surface or only to certain surface areas of the paper substrate 14. The release layer 18 is usually based on silicone, but other release agents, for example based on polyacrylate, carbamate or polyvinyl ether wax, can generally also be used. The application weight of the release layer 18 is usually between 0.1 and 2.0 g/m2, in particular between 0.2 and 1.0 g/m2.

[0028] Alternatively, the release layer 18 can be dispensed with and instead the adhesive layer 16 can be covered with a release foil (not shown) or a release paper, for example a silicone paper.

[0029] Optionally, the paper substrate 14 can be printed, in particular on the non-adhesive side. If a release layer 18 is provided, printing is preferably carried out directly on the paper substrate 14 before coating with the release layer 18. Printing can be carried out by gravure, flexography, offset or another printing method. The printing ink can be based on NC, PU, PVC, PVB or other binders. Optionally, an additional lacquer coating (not shown) can be applied between the print layer and the release layer 18. In this case, the layer structure of the layer system 12 would be adhesive layer 16-paper substrate 14-print layer-lacquer layer-release layer 18.

[0030] Fig. 3 shows a schematic perspective view of a tear-off strip reel 26. For this purpose, the tear-off strip 10 is wound onto a core 24. Preferably, the tear-off strip 10 is wound in this way with a transverse winding, which allows a large run length of up to 40,000 m, typically 10,000 to 20,000 m. Alternatively, the tear-off strip 10 can also be made up as a flat reel. The tear-off strip 10 can be cut into narrower strips. The typical strip width for the most common packaging 28 is approximately 2 to 15 mm, in particular 4 to 8 mm. Typically, the cutting is carried out with a scissor cut, but other types of cutting or separating are also possible.

[0031] Fig. 4 shows a top view of an unfolded packaging 28, on which another exemplary embodiment of the tear-off strip 10 according to the invention is arranged. Fig. 4 is explained together with Fig. 5, which shows an enlarged view of detail V. In particular, it can be seen from Fig. 5 that the adhesive layer 16 in the present case has a regular dot pattern with punctual elevations 20 and corresponding depressions 22.

[0032] The parameter values specified in the documents for the definition of the process and measurement conditions for the characterization of specific properties of the object of the invention are also to be considered within the scope of the invention in the context of deviations - for example, due to measurement errors, system errors, weighing errors, DIN tolerances and the like. LIST OF REFERENCE SYMBOLS:

[0033]

10 tear-off strips

12 layer system

14 paper substrate

16 adhesive layer

18 separation layer

20 lifts

22 depressions

core

tear-off strip reel

packaging

main extension address

extension vector

Claims (15)

1. Tear-off strip (10) for a packaging (28), comprising a layer system (12) having a paper substrate (14) and an adhesive layer (16) arranged on a first side of the paper substrate (14), characterized in that the adhesive layer (16) has, at least in areas, an irregular surface structure with relative elevations (20) and relative depressions (22). 2. Tear-off strip (10) according to claim 1, characterized in that the paper substrate (14) is compostable and/or biodegradable and/or the paper substrate (14) has a grammage between 80 g/m2 and 200 g/m2, in particular between 100 g/m2 and 140 g/m2, and/or the paper substrate (14) has in a main direction of extension (H) a stability of at least 75 N/15 mm, preferably at least 110 N/15 mm and/or a thickness between 100 |_im and 250 |_im, in particular between 150 |_im and 200 |_im. 3. Tear-off strip (10) according to claim 1 or 2, characterized in that the first and/or a second side of the paper substrate (14) is embossed and/or bleached and/or colored and/or printed. 4. Tear-off strip (10) according to one of claims 1 to 3, characterized in that the adhesive layer (16) is applied over the entire surface or in regions on the first side and/or that the adhesive layer (16) has an application weight between 15 g/m2 and 60 g/m2, in particular between 20 g/m2 and 30 g/m2 and/or that the adhesive layer (16) has a regular surface structure, in particular a dot structure and/or a wave structure and/or a line structure and/or a pyramidal structure and/or a truncated pyramidal structure and/or a hexagonal structure and/or a line structure with cells and/or a calotte structure. 5. Tear-off strip (10) according to claim 4, characterized in that the surface structure of the adhesive layer (16) has, at least in regions, a periodic structural element, where at least one extension vector (V) of the periodicity of the structural element is preferably arranged obliquely to the main extension direction (H) of the paper substrate (14). 6. Tear-off strip (10) according to one of claims 1 to 5, characterized in that a separating layer (18) is arranged over the entire surface or in regions on the second side of the paper substrate (14), wherein an application weight of the separating layer (18) is preferably between 0.1 g/m2 and 2.0 g/m2, in particular between 0.2 g/m2 and 1.0 g/m2. 7. Tear-off strip (10) according to one of claims 1 to 6, characterized in that a separating strip is arranged on one side of the adhesive layer (16) opposite the paper substrate (14). 8. Tear-off strip (10) according to one of claims 1 to 7, characterized in that it is wound on a reel (26) with a preferably transverse winding and/or manufactured as a flat reel. 9. Method for producing a tear-off strip (10) for a packaging (28), in which a layer system (12) is produced by applying an adhesive layer (16) to a first side of a paper substrate (14), characterized in that the adhesive layer (16) is produced, at least in zones, with an irregular surface structure with relative elevations (20) and relative depressions (22). 10. Method according to claim 9, characterized in that the paper substrate (14) is provided with an irregular surface structure before the application of the adhesive layer (16) and/or that the irregular surface structure occurs in the adhesive layer (16). 11. Method according to claim 9 or 10, characterized in that the adhesive layer (16) is applied to the paper substrate (14) by means of an anilox roller, in particular a tri-helical roller. 12. Method according to one of claims 9 to 11, characterized in that the paper substrate (14) is provided on a second side with a printing layer and/or a separation layer (18). 13. Method according to claim 12, characterized in that a lacquer layer is applied between the printing layer and the separation layer (18). 14. Method according to one of claims 9 to 13, characterized in that the tear-off strip (10) is cut into several strips, preferably by scissor cutting, where the strips preferably have a width of between 2 mm and 15 mm, in particular between 4 mm and 8 mm. 15. Packaging (28) comprising at least one tear-off strip (10) which is formed according to one of claims 1 to 8 and/or produced by a method according to one of claims 9 to 14.