Method for manufacturing a film having a laser-engraved predetermined breaking point

Abstract

A cost-effective method for producing a film (1) as part of a packaging container (K) to at least partially define an inner cavity (6) of the packaging container (K) is proposed, wherein the film (1) is designed to tear at a predetermined breaking point under the action of mechanical pressure, thereby releasing access to the inner cavity (6), the method comprising: - providing the film (1) as a single-layer film or a composite film having at least one layer (2, 3), wherein at least the outer layer and / or the inner layer (2) with respect to the inner cavity (6) is composed of plastic, - removing a portion of the film (1) by means of a laser to produce the predetermined breaking point in the form of a laser engraving (4), wherein the removal is effected by the laser locally reducing the film thickness, so that the predetermined breaking point is designed as the laser engraving (4).

Description

Technical Field

[0001] This invention relates to a method for manufacturing a film according to the preamble of claim 1 and a packaging container according to the preamble of claim 10. Further, it proposes a film according to the preambles of claims 11 and 12 and a packaging container according to the preamble of claim 20. Background Technology

[0002] Various blister pack containers are known from the prior art, such as tablet packaging in the form of puncture-packing and coffee capsules for preparing hot coffee beverages. Such tablet packaging has traditionally used aluminum foil as a capping film on thermoformed parts. Modern tablet packaging aims for greater sustainability. This is why they now avoid using aluminum and use only plastic. While some coffee capsules have traditionally also been made of aluminum, attempts are now being made to use recycled materials, such as plastics, as described in EP 4 173 978 A1, and / or compostable materials as proposed in EP 3 847 014 A1, to create more environmentally friendly products. This is because capsules are typically single-use items, discarded after a single use. However, it has been found that the manufacturing process is generally more expensive when using such aluminum alternatives. Summary of the Invention

[0003] One object of the present invention is to provide a thin film and a method for manufacturing the corresponding thin film, which can eliminate these disadvantages and, in particular, allow for more cost-effective manufacturing without loss of quality.

[0004] Starting with the type of thin film and manufacturing method described at the beginning, this objective is achieved by the characteristic portion of claim 1.

[0005] The measures described in the dependent claims enable advantageous embodiments and improvements of the invention.

[0006] The packaging container (e.g., a coffee capsule) described in this invention stores coffee powder or powder for beverage preparation. For this purpose, the coffee capsule has an inner cavity. Preparation itself is typically achieved by rinsing the inner cavity, allowing hot water to enter and thus contact the powder. To establish a passage to the inner cavity, the capsule needs to be opened or broken. For this purpose, a film is provided that at least partially defines the capsule's inner cavity. This film is typically used as a capping film for the capsule. For example, in the case of a blister pack, the film is easier to puncture than a relatively thick plastic groove.

[0007] The tablet packaging described in this invention can be, for example, a pressure-perforation packaging. Fingers are used to apply pressure to the thermoformed part. The force is transferred to the tablet and subsequently to the film to be torn, causing the tablet to emerge from the cavity.

[0008] Initially, aluminum foil was used, such as the aluminum foil commonly used for packaging and storing food. However, aluminum manufacturing is not particularly environmentally friendly.

[0009] In the case of coffee capsules, the film can traditionally be broken mechanically using spikes that drill into it. However, there is a risk, especially with plastic films and capsules, that film particles or residue could detach and enter the beverage, which is to be avoided for various reasons (health, quality, and hygiene). Furthermore, plastic films generally have worse tear resistance than aluminum foil. Traditional plastic tablet compression packaging is also typically harder to open than packaging with aluminum foil caps, requiring more force. Moreover, if the plastic film has an additional barrier layer, its tear resistance is usually not as good as aluminum foil, thus casting doubt on its suitability for packaging. Mechanical breaking of plastic films, such as single-layer or recyclable films, can also be achieved using high pressure applied to the capsule with vapor. However, the risk of film particles or residue detaching remains here as well. Traditional tablet compression packaging carries the same risk.

[0010] To improve the tear resistance of plastic films used as alternative films, they can be indented with very fine notches using a roll forming die. However, the inventors have recognized that this technique is costly because it is complex and involves high tooling costs, as not only must the roll forming die be manufactured, but it also wears out quickly as a tool. Furthermore, temperature effects can cause expansion problems. Manufacturing procedures are inflexible, and a new die may need to be manufactured for each adjustment. Requirements regarding durable quality cannot be met.

[0011] Therefore, the present invention is characterized by creating a predetermined fracture point that breaks under mechanical pressure at a defined location within the film. This predetermined fracture point is generated by laser engraving, rendering mechanical dies, for example, unnecessary. Thus, tool wear is essentially completely avoided.

[0012] However, the laser engraving according to the present invention provides further advantages:

[0013] When changes occur, such as changes to the capsule product to be manufactured—for example, changes to the shape / contour of the predetermined break point or the depth or width of the predetermined break point—complex and expensive new tools are not required. Instead, reprogramming the laser's control system is usually sufficient.

[0014] Even when the capsule material changes, such as to different plastics, different tools are usually not required; only the control sequence needs to be changed.

[0015] Therefore, changeover time is also greatly reduced, as it usually only requires reprogramming the control system, which is typically much faster than manufacturing the die. This enables higher production volumes.

[0016] To ensure the film fractures cleanly and geometrically, laser engraving can be designed linearly. Alternatively, weak points can be created in the material through dotted recesses. Especially when opening the capsule by mechanical pressure, particularly by steam, at the predetermined fracture point region—for example, when rinsing the capsule cavity with hot water to prepare a beverage—it is crucial to minimize the entry of film residue or particles into the water and subsequently into the beverage. Therefore, it is advantageous to provide a predetermined fracture point extending over a relatively long distance, otherwise the film material would need to tear at locations where its thickness is not weakened, which in turn could make individual film components more prone to tearing. The more defined the predetermined fracture point created by laser engraving, the better the repeatability and quality of the beverage preparation results are likely to be.

[0017] Similarly, such particles from the capping film should also be avoided as residue on the tablet.

[0018] To completely separate a surface area, the closed surface area of ​​the film can, in principle, be laser-engraved. However, in the case of coffee capsules, it is generally not intended to separate the continuous surface from the film by pressure, because although the capsule, as a packaging container, is to be opened, it should not be divided into multiple parts, as this could, for example, obstruct water flow.

[0019] In an improved embodiment of the invention, laser engraving is performed as a so-called cold removal process. Cold removal enables engraving, for example, without molten edges, thus maintaining a smooth film surface. Any edge thickening can lead to undesirable deposition, such as tiny contaminant particles. It can also cause sealing problems or similar issues, and is therefore a rather disruptive artifact. This cold removal can be achieved, for example, with a laser emitting in the ultraviolet range, such as at a wavelength of 355 nm. In contrast, carbon dioxide lasers result in the removal of material with molten edges.

[0020] For environmental reasons, the film and its corresponding packaging containers (e.g., tablet packaging or coffee capsules) can be aluminum-free. Recyclable materials can be used instead. Compostable materials are also considered in principle. For example, plastics are generally easy to recycle. In some cases, some plastics can also be composted. To allow the film to open at a predetermined break point by the steam pressure generated in a coffee maker or coffee pot, it is advantageous for the film to be as thin as possible, for example, in the form of a single-layer monolayer. However, composite materials, which achieve defined properties as a combination of the functions of different materials, can also be considered. One layer, especially the outer layer on the surface, can be designed to also have a laser-engraved plastic layer. It is also possible that at least two or all layers are made of plastic.

[0021] To protect food or medicine stored within the cavity, one layer can be, for example, a barrier layer, such as an EVOH layer (EVOH: a copolymer of ethylene and vinyl alcohol, prepared by the polymerization of ethylene and vinyl acetate). The barrier layer can also be laser-engraved to create a predetermined fracture point. In the case of using a barrier layer, in the prior art, it was previously almost impossible to achieve the desired fracture properties at the predetermined fracture point if only a die was used to weaken the material.

[0022] According to embodiments of the invention, the groove depth may, for example, comprise a single layer but not completely penetrate that layer, or comprise multiple layers. Typically, the laser engraving is wedge-shaped or blind-hole-shaped in a cross-section of the film perpendicular to its orientation and terminates within one of the film layers. If the film is not a single film, the overlying film layers or multiple film layers are completely penetrated. In the case of composite materials, the laser engraving may need to include more than one layer to allow the film to be opened.

[0023] Furthermore, due to its high tensile strength, biaxially oriented PET film (BOPET, where PET stands for polyethylene terephthalate) is also ideal for use in sealed food packaging. Film thicknesses typically range from, for example, 15 µm to 50 µm.

[0024] To achieve a good compromise between the strength and openability of the predetermined fracture point, the removal depth can range from 5 µm to 30 µm, while the notch width varies from approximately 15 µm to 50 µm depending on the example.

[0025] In one embodiment of the invention, an advantageous embodiment is a capsule in blister form. It comprises a molded plastic part or thermoformed component whose shape defines an internal cavity. It has an opening to which a film can be applied, attached, or sealed. The film is typically thinner and weaker than the thermoformed component, allowing predetermined break points to be integrated into the film. The blister can be transported relatively safely.

[0026] Accordingly, the manufacturing method according to the invention is characterized by creating predetermined fracture points in the form of laser engraving by removing a portion of the thin film with a laser. This removal is performed as a localized reduction in the film thickness and is carried out by a laser, such that the predetermined fracture points are in the form of laser engraving. Here, the advantages already explained regarding coffee capsules can be utilized. More environmentally friendly, aluminum-free capsules can be manufactured without mechanical tools, instead using optical tools (lasers used to generate the laser engraving). This saves costs and reduces manufacturing time. Furthermore, materials can be saved because no new tools need to be built due to wear or product changes. Factors such as temperature effects become less significant. The films or packaging to be manufactured have a lower scrap rate.

[0027] In an improved embodiment of the invention, the laser-engraved geometry is achieved using a mirror deflection system or a scanner. By programming a corresponding control system for the directional mirror, the laser beam can be guided to produce a wide variety of geometries.

[0028] Alternatively, one could keep the laser in a fixed position and instead use a positioning system to move the thin film relative to the laser beam to obtain the desired geometry.

[0029] The mesh structure can be implemented like parallel lines. Therefore, the line spacing can also be varied. In areas where lines would overlap, non-overlapping points can be created by interrupting the laser beam that would otherwise be incident there. The laser can also be temporarily shut off in those areas. These measures allow for setting the pressure or force required to anticipate film tearing at predetermined break points.

[0030] The present invention also proposes a coffee capsule which is de-embellished to produce engraved lines or marks without molten edges, such that the engraving can exist in the outer plastic layer.

[0031] For some packaging containers, especially for tablet packaging in push-through form, the film can also be arranged so that the laser engraving is on the inside, and the force is applied to the film from that inside. In principle, this arrangement can also be considered for coffee capsules. Attached Figure Description

[0032] Exemplary embodiments of the present invention are shown in the accompanying drawings and will be explained in more detail below by describing further details and advantages.

[0033] Specifically, the attached diagram shows:

[0034] Figure 1 A schematic cross-sectional view of the thin film according to the present invention.

[0035] Figure 2 A schematic cross-sectional view of the coffee capsule according to the present invention.

[0036] Figure 3 Schematic illustration of laser engraving according to the present invention, and

[0037] Figure 4 : A schematic illustration of a method for manufacturing coffee capsules according to the present invention. Detailed Implementation

[0038] Figure 1A schematic cross-sectional view of a thin film 1 comprising two layers 2 and 3 according to the present invention is shown. These two layers 2 and 3 are made of plastic. A laser engraving 4 is integrated into the thin film 1, having a notch width B and a depth T. The laser engraving 4 forms a predetermined break point in the thin film 1, its depth completely penetrating the outer layer 2 (here). Figure 1 Middle: Top layer 2). However, the laser engraving 4 also partially includes the bottom layer 3. Therefore, the thickness of the film 1 is locally reduced in the region of the laser engraving 4. As can be seen on both sides of the laser engraving 4, there are no molten edges on both sides of the laser engraving 4. In this case, the predetermined fracture point or the laser engraving 4 is wedge-shaped. Compared to a wider groove shape, this provides the advantage that the point can fracture more easily under pressure.

[0039] Figure 2 A schematic cross-sectional view of a coffee capsule K in the form of a bubble is shown. It consists of a cup-shaped thermoformed part 5, which is made of plastic thicker than the film 1, which acts as a covering film over the thermoformed part 5. An inner cavity 6 of the coffee capsule K is located within the thermoformed part 5, its top defined by the covering film 1, and the cavity is filled with coffee powder. The film 1 is sealed at the edge of the thermoformed part 5.

[0040] exist Figure 3 In the film 1, a predetermined break point containing laser engraving 4 can be seen. It is circular, and the engraving 4 is interrupted at a certain point so that the material does not enter the coffee during brewing; that is, the cap portion in the middle of the predetermined break point remains connected to the film 1.

[0041] Figure 4 A manufacturing method is outlined:

[0042] - It can provide thin films.

[0043] - The laser is positioned relative to the thin film using a scanner.

[0044] -Then laser engraving is performed, with the laser still traveling along the predetermined engraving lines through the scanner.

[0045] - If necessary, the film can be cleaned or sterilized, for example, by gently blowing it with gas.

[0046] Simultaneously, a blister can be created. This is achieved by performing the following steps:

[0047] - Deep drawing of the formed parts.

[0048] - For example, cleaning deep-drawn parts by blowing.

[0049] - Fill the capsule with coffee powder. Optionally, this is done under an inert gas atmosphere, allowing the coffee powder to remain in capsule K for a longer period without losing its flavor. Weighing is performed during filling, or the pre-measured amount of powder is used for filling.

[0050] The deep-drawn part 5 and the film 1 together constitute the finished capsule K. The film 1 and the deep-drawn part 5 must be connected to each other, i.e., heat-sealed, so that ambient air cannot reach the coffee powder stored in the inner cavity 6 and damage it or its flavor.

[0051] All exemplary embodiments and improvements of the present invention share the common feature of creating a predetermined fracture point so as to tear and release the channel to the inner cavity by mechanical pressure at the predetermined fracture point, at least relative to the outer or inner layer of the inner cavity being made of plastic; they differ in that the predetermined fracture point is in the form of laser engraving, wherein the film thickness is locally reduced by laser removal.

[0052] List of reference numerals

[0053] 1 film

[0054] 2. Outer plastic layer

[0055] 3 Additional Layers

[0056] 4. Laser engraving

[0057] 5. Deep-drawn parts

[0058] 6. Capsule cavity

[0059] 7. Interruptions in carving

[0060] B. Scratch width

[0061] K coffee capsules

[0062] T represents the depth of the serration.

Claims

1. A method for manufacturing a film (1) as part of a packaging container (K) to at least partially define the interior cavity (6) of the packaging container (K), wherein, The film (1) is designed to be torn at a predetermined fracture point by mechanical pressure, thereby releasing a channel to the inner cavity (6), the method comprising: • The film (1) is provided as a single-layer film or a composite film having at least one layer (2,3), wherein at least the outer layer and / or the inner layer (2) relative to the inner cavity (6) is made of plastic. • A portion of the thin film (1) is removed by laser to generate a predetermined fracture point in the form of laser engraving (4). The removal is achieved by locally reducing the thickness of the thin film by laser, so that the predetermined fracture point is designed to be laser engraved (4).

2. The manufacturing method according to claim 1, characterized in that, A UV laser preferably in the wavelength range of 355 nm is used as the laser to enable cold removal, in particular, without forming a molten edge in the edge region of the laser engraving (4).

3. The manufacturing method according to any one of the preceding claims, characterized in that, The laser beam of the laser used to remove and / or create the laser engraving (4): • Positioned relative to the thin film via a mirror deflection system, preferably by a scanner, and / or • Maintain a fixed position while the thin film (1) moves relative to the laser beam.

4. The manufacturing method according to any one of the preceding claims, characterized in that, The following materials are provided as the thin film (1): • Thin films with a thickness of 15µm to 50µm, and / or • 2-layer BOPET film.

5. The manufacturing method according to any one of the preceding claims, characterized in that, Laser engraving with a groove width of 15µm to 50µm is produced during removal (4).

6. The manufacturing method according to any one of the preceding claims, characterized in that, Laser engraving (4) with a groove width of 15µm to 50µm is produced during removal, and / or the laser engraving is produced to a depth of 5µm to 30µm by the removal.

7. The manufacturing method according to any one of the preceding claims, characterized in that, The fracture characteristics of the predetermined fracture point (4) are set in the following manner: • Remove the mesh structure as described in the laser engraving, and / or • Remove at least two parallel lines as described in the laser engraving, and / or • Change the line spacing of the laser engraving (4) during removal.

8. The manufacturing method according to any one of the preceding claims, characterized in that, In addition to the lines, at least one dotted structure is removed.

9. The manufacturing method according to any one of the preceding claims, characterized in that, By interrupting the laser beam in the overlapping areas and / or turning off the laser there, non-overlapping cross lines are produced as the laser engraving (4).

10. A method for manufacturing a packaging container, wherein the packaging container is particularly a coffee capsule (K) and / or tablet package and / or puncture package and / or transparent package and / or blister pack, wherein, A plastic molded part (5) forming an inner cavity (6) is molded and is at least partially covered by and connected to a film (1) serving as a rear wall, so as to at least partially define the inner cavity (6), characterized in that the method for manufacturing the film (1) according to any one of the preceding claims is used.

11. A film (1) or packaging container (K) that can be obtained according to any one of the preceding claims.

12. A film (1) for at least partially defining an inner cavity (6) of a packaging container (K), said film (1) being designed as a single-layer film or a composite film having at least one layer (2,3) and having a predetermined tear point for tearing at said predetermined tear point by mechanical pressure, thereby releasing a passage to the inner cavity, said layer or at least one outer or inner layer (2) being made of plastic, characterized in that, The predetermined fracture point is designed to be laser-engraved (4), wherein the film thickness is locally reduced by laser removal.

13. The thin film (1) according to any one of the preceding claims, characterized in that, The laser engraving (4) is designed at least partially, and in particular entirely, in a linear manner, and / or forms a closed surface area on the film (1).

14. The thin film (1) according to any one of the preceding claims, characterized in that, The laser engraving (4) is defined as having no molten edge and thus there is no local thickening of the film (1) at the edge of the engraving (4).

15. The thin film (1) according to any one of the preceding claims, characterized in that, The thin film (1) and / or all layers (2,3): • Made of plastic, and / or • Made of recyclable materials, and / or • Aluminum-free.

16. The thin film (1) according to any one of the preceding claims, characterized in that, Provide at least one barrier layer, particularly an EVOH layer.

17. The thin film (1) according to any one of the preceding claims, characterized in that, The removal of the laser engraving (4) involves at least one layer of the thin film (1), and in particular all layers (2, 3).

18. The thin film (1) according to any one of the preceding claims, characterized in that, The thin film (1): • With a thickness of 15µm to 50µm, and / or • Designed as a 2-layer BOPET film.

19. The thin film (1) according to any one of the preceding claims, characterized in that, The removal process results in the laser engraving having a depth of 5µm to 30µm and / or a groove width of 15µm to 50µm.

20. A packaging container (K) comprising a film (1) according to any one of the preceding claims, and / or a film (1) manufactured according to any one of the preceding claims.

21. The packaging container (K) according to any one of the preceding claims, characterized in that, Its design is as follows: • Coffee capsules, and / or • Tablet packaging, and / or • Pressure-piercing packaging, and / or • Transparent packaging, and / or • A blister, in particular including a plastic molded part (5) for forming the inner cavity (6) and a film (1) serving as the rear wall of the plastic molded part.

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