Method for joining two film portions with localized tearing means

Abstract

To provide a method for producing a metering supply opening portion in a film packaging material without incorporating a rigid molded body or causing problems when opening the packaging material.SOLUTION: The present invention relates to a method for joining two film portions during production of a moulded body provided with localised opening means, formed at least in part from one or more films, in which the two film portions 2 are joined together by a seal. The method involves irradiating at least one of these film portions with an electron beam locally, completely, or in one or more partial regions 3 before sealing, thereby reducing a strength of a sealing seam formed by sealing in each irradiated region. The packaging material is opened by a user simply compressing the packaging material at a point that is pre-determined by an electronic process.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for joining two film sections during the production of a molded article with a localized opening means, which is at least partially formed from one or more films, at least one of which is a thermoplastic film or a film section coated with a thermoplastic material, and which is joined to one another by a seal.The present invention also relates to a molded article, in particular a film packaging, which has been provided with a localized opening means by a method according to the invention.

[0002] The proposed method can be used particularly advantageously in the production of packaging materials. Packaging materials for flowable, pasty or powdery products require an opening means that is easily handled by the user. This opening means can consist of a rigid shaped body (e.g., a spout) that is introduced into the original film packaging, or can be generated by a defined opening means. The secure and sealed introduction of the shaped body is technically complex and involves high technical risks. This opening variant involves significant drawbacks in terms of handling by the user, the dosing ability of the package, and hygiene. Therefore, there is a need for a method for easily producing a dosing opening part in a film packaging material that is easily opened by the user without incorporating a rigid shaped body.

[0003] Background technology Various techniques for producing a metered opening in a packaging material are known. For example, EP 2284095 A1 describes a packaging material with a pre-cut opening that can be opened and closed reversibly. To produce this opening, a spout is introduced into the packaging material. EP 2106373 A1 discloses a film packaging material in which the closure seam has a sawtooth-like extension with a notch and is connected to a tear aid for opening the packaging material. The provision of an easily opened sealing seam for opening the packaging material is described, for example, in German EP Patent Translation No. 60312958 (T2).

[0004] As already mentioned, both the rigid molding technique and the opening variants described above have manufacturing or handling drawbacks as well as drawbacks in terms of dosing ability and hygiene.

[0005] The object of the present invention is to provide a method for providing an opening means during the production of a film packaging material without incorporating a molding, thereby simplifying the production process and eliminating technical risks, such that the user can simply open the packaging material accordingly to remove the product or mix two components by opening the internal chamber separator.

[0006] Description of the Invention The above-mentioned problem is solved by the method described in claim 1. Claims 11 and 12 describe a shaped body, preferably as a film packaging, which is provided with a corresponding opening means by the proposed method. Advantageous configurations of the method and of this shaped body are the subject of the respective dependent patent claims or are described in the following description and examples.

[0007] In the proposed method, two film segments are joined together by a seal when producing a molded body with a localized tearing mechanism. The molded body, particularly a film packaging, is at least partially formed from one or more films. The first of the two film segments is a sealable, preferably thermoplastic, plastic film or a film segment coated with a sealable, preferably thermoplastic, plastic. This method is characterized by irradiating at least the first film segment with an electron beam locally, completely, or in one or more partial regions, before sealing, thereby reducing the strength of the seal seam formed by the seal in each irradiated region. In this case, the localized irradiation can be carried out with a focused electron beam or an electron beam with a small beam diameter. The electron beam scans each region. However, the irradiation is preferably carried out using a mask or masking, for example made of a metallic material, so that the electron beam can penetrate the film segment only at the corresponding tearing point. In this way, a technically simple system for generating an electron beam can be used, operating over a wide width or large surface area. Preferably, the two film portions are portions of a sealable, preferably thermoplastic, plastic film or a film coated with a sealable, preferably thermoplastic, plastic, and irradiation is carried out correspondingly completely in these two film portions or in one or more corresponding partial areas of each of these film portions.

[0008] This method utilizes the fact that the electron beam reduces the significant increase in polymer chain mobility of the plastics or polymers of the sealable plastic film or sealable plastic layer used in sealing, thereby achieving a lower seal seam strength in the irradiated areas compared to the non-irradiated areas. The desired seal seam strength can be set via the irradiation dose, and this seal seam strength is also related to the plastics or polymers irradiated. In the packaging field, polyolefin films are often used, and packages are formed from polyolefin films by enclosing a volume with the film. In this case, the film may consist of multiple parts or materials. At appropriate locations, the film is joined to itself or another part by a seal. The purpose of sealing a package is to ensure a tight and fixed connection between sealable packaging materials.

[0009] The most commonly used methods for sealing packaging materials are thermal contact sealing (heat sealing) and cold sealing (cold sealing). During cold sealing, only pressure is required to join two webs coated with a cold adhesive. During thermal contact sealing, heat is applied to two sealable packaging materials or films, one above the other, for a defined period of time under pressure using a heated sealing tool. This results in melting of the plastic (which is accompanied by a significant increase in polymer chain mobility) or at least a significant increase in polymer chain mobility. Both methods result in the mixing of the plastic at the contact point of the sealable packaging materials or films. Then, upon cooling of the sealing point, the two plastic films become inseparable. Alternatively, for example, metal films can be used, at least one of which is coated with a corresponding layer of a sealable, preferably thermoplastic, plastic. Further examples of sealing methods are laser sealing or ultrasonic sealing, which ultimately also rely on the mixing of the materials to be joined. In the proposed method, any sealing method that causes a significant increase in polymer chain mobility during sealing can be used, and this significant increase in polymer chain mobility can be reduced by irradiating with an electron beam before sealing.

[0010] When used in the packaging sector, the thermal contact sealing preferably used in the proposed method is carried out in several sequential process steps, between which the packaging material is filled with the goods to be packaged. Finally, a fully closed packaging material containing the filled goods is obtained. The strength of the seal seam is specified under uniaxial tensile stress transverse to the seal seam (e.g., DIN 55529:2012-09). Depending on the seal seam strength, the opening properties are classified starting from soft peel (up to 6 N / 15 mm), through easy peel (6 N / 15 mm to 10 N / 15 mm) and peel (10 N / 15 mm to 15 N / 15 mm), and up to stick (>15 N / 15 mm).

[0011] In the proposed method, for example, when sealing two film sections to produce the above-mentioned packaging material, electrons are applied locally to the entire film section or a partial region of each section to be sealed, depending on the intended size of the subsequent tearing opening. This (irradiated) region is thereby characterized by a reduced seal seam strength compared to the same or other seal seam regions of the molded body under the same sealing parameters, thereby providing a localized tearing means at this location. It should be understood that locally irradiating a film section or a partial region here always means applying the electron beam only to the film section or a partial region of this section, rather than to the entire film. In this way, the electronically treated region defines the tearing area for the subsequent packaging material or the subsequent molded body. The user can now simply compress the packaging material. The increasing pressure causes tearing at the weakest point of one or more seal seams, which were previously determined by the electronically treated region.

[0012] To prevent the packaged article from uncontrollably popping out of the opening, the electronically processed area may be specially shaped and / or structured. Thus, the partial area of the film portion to be processed by the electron beam may have, for example, a trapezoidal shape, which, in turn, widens outward from the inner volume of the packaging material. A meander-like structure of the partial area may also be advantageous for preventing popping out. The electronic processing may also be carried out with varying intensity across the irradiated area, thereby varying the opening force across the irradiated area of the seal seam. The gradient of the dose applied to each area, and thus the variation of the seal seam strength across this area, can be achieved, for example, by varying the thickness of the masking material when irradiating the film portion using masking.

[0013] The proposed method not only creates an opening means for the packaging or molding that leads to the outside, but also allows for the opening of two or more separate chambers of the packaging or molding separated by a sealing seam. This separation can, for example, prevent two different fillings from mixing. If a partial region of the inner sealing seam is pre-treated electronically, this sealing seam can be opened more easily at the corresponding point by applying force to the entire packaging than an untreated sealing seam on the outer side. This allows the mixing of the fillings at a defined time without opening the packaging, preventing the fillings from leaking out of the packaging or, for example, interacting with the air. Such a configuration is used, for example, in adhesive areas.

[0014] The use of small amounts of suitable additives during the production of sealable plastic films or during the coating of sealable plastic films can further enhance the effects of electron beam irradiation on the formation of branches and crosslinks, and thus the reduction of polymer chain mobility. Additives here refer to functional additives (plasticizers, nucleating agents, rheology modifiers, impact modifiers, etc.), process additives (lubricants, anti-slip agents, etc.), and reactive additives. Reactive additives enhance the effects of electron processing by forming branches and crosslinks. Reactive additives are defined as substances capable of forming radicals. Polyfunctional monomers, oligomers, and polymers, such as acrylates, methacrylates, bismaleimides, metal salts, high-vinyl 1,2-polybutadienes, divinylbenzenes, and allyl esters of cyanurates, isocyanurates, or sulfur, are particularly suitable.

[0015] For electron processing, the proposed method preferably utilizes an electron acceleration system, which is also used, for example, in the printing and coating fields, for crosslinking printing inks or curing paints. In this case, electrons, which can move freely in a vacuum, are generated, for example, by thermionic emission and accelerated to energies of up to several hundred keV by applying an electric potential. Depending on the electron energy, they can pass through thin metal films or other electron-transparent materials. This is used to transfer the electrons from the vacuum to a region under atmospheric pressure, where the irradiation of the film portion in the proposed method is then carried out. In the atmosphere, these electrons have a range of several tens of centimeters. Accordingly, the material to be processed can be positioned in front of or guided through an electron exit window at a distance of several centimeters to interact with the electrons. However, the proposed method does not exclude electron processing with other technical systems. Here, irradiation is preferably carried out with an electron dose ranging from 10 to 100 kGy, depending on the material to be irradiated and the desired seal seam strength.

[0016] The proposed method can be advantageously used in the production of packaging for food, cosmetics, pharmaceuticals, chemicals and other powdery or pasty materials, adhesives, greases, oils, etc. Although the primary application is in providing opening means in such packaging or between the individual chambers of such packaging, the proposed method can also be used in the production of other molded bodies that are partially formed from one or more films and in which corresponding opening means are to be provided. An example of this is a plastic hopper consisting of two films sealed together, which has one or more points at which fluid should flow out at a defined point from a certain filling height of the hopper.

[0017] The proposed method will be explained in more detail below again on the basis of an example and with reference to the drawings. [Brief explanation of the drawings]

[0018] [Figure 1] 2 is a schematic diagram of a first example of the form of a partial area irradiated with an electron beam according to the proposed method; [Figure 2] Schematic diagram of a second example of the form of a partial area irradiated with an electron beam according to the proposed method. [Figure 3] Schematic diagram of a third example of the form of a partial area irradiated with an electron beam according to the proposed method. [Figure 4] Schematic diagram of a fourth example of the form of a partial area irradiated with an electron beam according to the proposed method. [Figure 5] FIG. 10 shows an example of the seal seam strength related to the strength of the electronic processing according to the proposed method.

[0019] Methods of carrying out the invention In the following examples, film packages are produced, and corresponding film portions of these film packages are joined together by sealing. According to the proposed method, the portions to be sealed or partial regions of these portions are treated with an electron beam before sealing, so that the seal seam strength is reduced to a defined extent in each irradiated region relative to the remaining regions of the film package or other seal seams.

[0020] In this regard, FIGS. 1 to 4 show, in a highly schematic view, an example of a film packaging 1, in which two films with corresponding film portions 2 are stacked one on top of the other and sealed at the top edge of the film packaging 1. Here, before sealing, a partial region of at least one of these portions is treated with an electron beam, resulting in a reduced seal seam strength compared to the remaining areas. For this purpose, in the example of FIG. 1, a rectangular partial region 3 is treated with the electron beam. In the example of FIG. 2, the electron beam is irradiated on a trapezoidal partial region 4, which has an outwardly expanding trapezoidal shape. In the example of FIG. 3, the electron beam is irradiated on a meander-shaped partial region 5. These two shapes of the partial regions prevent the contents from rapidly popping out when sufficient pressure is applied to the packaging. Here, the seal seam begins at the inner volume of the packaging and opens outward depending on the irradiated partial region. Furthermore, the irradiation dose can be varied across the subregions, resulting in a gradient in the seal seam strength, as shown for example in the example of Fig. 4 by the subregion 6 with varying electron doses. This also allows the opening process to be controlled, thereby reducing the risk of the contents popping out.

[0021] In the following, various examples of the use of the proposed method will be described for different packaging materials.

[0022] Usage example 1 - Ketchup packaging, horizontal orientation: A 22-cm-wide plastic film made of a 50 / 50 HDPE and LDPE blend is wound into a 1,000-m-long roll. This 100-μm-thick film is rewound in a roll-to-roll machine. During rewinding, each 1-cm-wide edge area is irradiated with a 50-kGy dose using an electron beam irradiator, whose timing is controlled by the web speed. The clock frequency is set so that a 1-cm-long film area is irradiated every 5 cm of film length. The electron beam irradiator operates at an accelerating voltage of 150 kV. The treated plastic film is then transported to a machine for packaging formation. Here, the film material is folded in the center along the machine direction, resulting in a two-layered web 11 cm wide. The edge areas treated by the electron beam are then positioned on top of each other. The web is then sealed crosswise to the machine direction every 5 cm using 2-cm-wide hot seal jaws. In this case, the sealing is performed so that the areas treated by the electron beam are each positioned in the center between the transverse seals. The bags thus obtained are filled and then the still open side is sealed and closed using 1 cm wide sealing jaws. The bags are then separated. Individual bags 5 cm wide and 11 cm high are obtained, which are filled with ketchup. A simple manual pressure in the center of the 5 cm long sealing seam forms an opening through which ketchup can be easily dispensed.

[0023] For example, Figure 5 shows the seal seam strength of the above materials associated with different intensities of electron treatment. The set temperature of the sealing tool was 130°C in each case. As can be seen from Figure 5, the seal seam strength decreases as the intensity of the electron treatment increases (as the dose increases).

[0024] Example 1b - Ketchup packaging, longitudinal direction: A 5cm-wide packaging film laminate (multilayer structure) with a 35µm-thick sealing layer made of LDPE is wound as a roll. This 100µm-thick film is rewound on a roll-to-roll machine. During rewinding, the film is irradiated with a dose of 50kGy using an electron beam irradiator timed according to the web speed. The clock frequency is set so that a 2cm-long film area is irradiated across its entire width every 20cm of film length. The electron beam irradiator operates at an accelerating voltage of 150kV. The treated plastic film is then transported to a machine for packaging formation. Here, the film material is folded in the center along the machine direction, creating a two-layer web 2.5cm wide. The areas treated by the electron beam are positioned on top of each other. The web is then sealed along the machine direction on the open side using 1cm-wide hot seal jaws. The resulting tube-shaped packaging material is then filled in a timed manner and simultaneously sealed every 10 cm transversely to the machine direction using 2 cm-wide hot seal jaws. The sealing is performed so that each area processed by the electron beam is centered relative to the transverse seal. This process of aligned filling and transverse sealing results in a filled, fully closed bag. The bag is then singulated, each centered on the transverse seal, so that it is divided into two halves approximately 1 cm wide. Irradiation every 20 cm and matching sealing every 10 cm results in individual bags 2.5 cm wide and 10 cm long, filled with ketchup. A simple manual pressure can create an opening in only one of the two narrow sides, through which ketchup can be easily dispensed.

[0025] Use Example 1c - Ketchup packaging with a relatively small metered opening, longitudinal direction: The above example is modified so that the timed irradiation is not uniform across the entire width of the film web, but rather only the right and left sides are treated, each with a width of 1.5 cm, by appropriately masking the radiation with 1 mm thick stainless steel sheet metal. By subsequently folding the treated material web in the center, the treated areas are positioned one on top of the other, ensuring a treated width of only 1.5 cm on one side. This ensures that only one corner of the package is opened when the package is subsequently pressed down by hand, which additionally facilitates metering.

[0026] Use case 1d: Sachets for high viscosity cosmetic samples: For paste-like packaging, a pouch similar to that of Example 1c is produced. The sealing layer here consists of a material mixture of HDPE and LDPE (60 / 40) to which 0.8 pph of triallyl isocyanurate has been added. The total thickness of the laminate is 60 μm. Compared to Variant 1c, this pouch has a reduced opening force, making it a more suitable personal care product for the elderly.

[0027] Usage example 2 - Packaging machines including electron beam equipment A 1,000-meter-long, 22-cm-wide plastic film made of a 50 / 50 HDPE and LDPE mixture is wound into a roll. This 50-μm-thick film is fed into a packaging machine, which semi-continuously produces, fills, and seals the packaging material using the appropriate folding and hot-sealing processes. The packaging machine is equipped with an electron irradiator, which is timed to operate in sync with the entire system and irradiates trapezoidal areas at each web edge with a dose of 50 kGy at an accelerating voltage of 130 kV. The trapezoidal shape is generated by a suitably configured metal mask between the electron irradiator and the plastic film. Before the electron irradiator, the web material is folded in the center, resulting in two 11-cm-wide webs. The open film side of the web, which is positioned on top of each other, is irradiated by the electron irradiator. The entire machine is timed to seal the web every 5 cm across the machine direction using 2-cm-wide hot-sealing jaws. In this case, the sealing is performed so that the area treated by the electron beam is centered between the transverse seals. The resulting bags are then filled and then sealed at the open side using 1 cm wide sealing jaws, thus closing them. The bags are then separated. Individual bags are obtained, 5 cm wide and 11 cm high, with an opening means in the center of the 5 cm long sealing seam. This opening means can be opened by applying pressure to the bag; in this case, the trapezoidal irradiation profile ensures that the contents of the bag can be dispensed and removed without spilling out.

[0028] Usage example 3 - Multi-chamber packaging material A packaging material for a two-component adhesive is produced from a 10 cm-wide film web, which is modified in 5 mm-wide areas (2 cm apart on each side of the center) by electronic treatment (35 kGy, 120 kV). The film web is then folded so that the treated areas overlap each other, and the folded film web is sealed with uniform sealing parameters in the 5 mm-wide edge area and the 5 mm-wide treated area, resulting in a web material with two side-by-side chambers, where the inner seal seam has easy-peel properties and the outer seal seam has adhesive properties. The two adhesive components are then loaded separately into the left and right chambers, and after 15 cm, the web material is provided with a 1 cm-wide transverse seal, which is then individualized. The end user of the adhesive can then mix the two components immediately before use without opening the packaging by applying pressure and kneading the packaging, since the inner separation point is relatively easy to open, and the mixed adhesive is then removed for use.

[0029] Use Example 4 - Sauce bottle with sealed film closure For sauces with metered dispensing closures, a film is typically sealed to the container opening, which ensures product protection before initial opening. When the same material is used for these films as for the container, the sealing force is often so high that initial opening becomes significantly more difficult. To address this issue, a cover film made of HDPE doped with 0.5 pph trimethylolpropane triacrylate is rewound in a roll-to-roll system. During rewinding, it is irradiated with a dose of 50 kGy by an electron irradiator timed according to the web speed. The clock frequency is set so that the area of the cover film where the tear tab is located is irradiated during further processing. The electron irradiator operates at an accelerating voltage of 150 kV. The cover film is then heat-sealed to the HDPE container. The combination of the reduced sealing force and the tear tab ensures easy opening.

[0030] Use Case 5 - Use of a Continuous Electron Emitter While the examples described so far have used timed electron emitters operating on both sides (mirror symmetry), the following examples will be described in which electron emitters operating continuously on one side of the film web are used.

[0031] A 21 cm wide plastic film (HDPE / LDPE 50 / 50) is continuously irradiated along the machine direction in 1 cm wide areas on one side. The film web is then folded in the center relative to the machine direction so that these edge areas are positioned on top of each other. 2 cm wide seals are then made transverse to the machine direction every 2.5 cm across the entire width of the folded web, and the individual packages are separated, with the separation occurring centrally within the seal. The individual packages are then filled, and the still-open narrow side is sealed, resulting in a fully closed package. The seal on the narrow side is characterized by a low seal seam strength due to electronic processing at this point, which allows for easy subsequent opening by hand.

[0032] When the proposed method for producing packaging is used, the packaging can be easily opened in a defined manner without the use of auxiliary means. No additional material is required to provide the opening means, which would otherwise be required, for example, as a tear tab. In this case, the entire packaging can be produced from one material (monomaterial) and, accordingly, can be easily recycled. [Explanation of symbols]

[0033] 1. Film packaging material 2 Sealed film part 3. Rectangular subarea to be illuminated 4 Irradiated trapezoid subarea 5 Irradiated meander-shaped partial area 6 Subregions with gradients in exposure dose

Claims

1. 1. A method for joining two film sections (2) during the production of a shaped article, in particular a film packaging (1), which is at least partially formed from one or more films and is provided with localized opening means, comprising: A method in which at least one first film portion of the two film portions (2) is a sealable plastic film or a film portion coated with a sealable plastic, and the two film portions (2) are joined to each other by sealing, 1. A method for sealing a film, comprising irradiating at least the first film portion (2) locally completely or in one or more partial areas (3, 4, 5, 6) with an electron beam before the sealing, thereby reducing the strength of the seal seam formed by the sealing in each irradiated area.

2. 2. The method according to claim 1, wherein the two film portions (2) are portions of a sealable plastic film or a film coated with a sealable plastic, and the irradiation is carried out with an electron beam on each of the two film portions (2) before the sealing.

3. 3. A method according to claim 1, wherein the irradiation is carried out using a mask, the mask determining the shape of the irradiated area.

4. 4. The method according to claim 1, wherein the irradiation is carried out in trapezoidal or meander-shaped partial areas (4, 5).

5. 5. A method according to claim 1, wherein the irradiation is carried out with a dose that varies over the partial area (6) or film portion.

6. 6. The method according to claim 1, wherein the irradiation is carried out at a dose of 10 to 100 kGy.

7. Method according to any one of claims 1 to 6, characterized in that the joining of the two film portions (2) is carried out by thermal contact sealing.

8. 7. The method according to claim 1, wherein a plastic film or a film coated with a sealable plastic is used, and an additive is added to the plastic, which promotes the formation of branches and crosslinks induced by the electron beam.

9. 9. A method according to any one of claims 1 to 8 for producing an opening means for a metered opening in a container as a shaped body.

10. 9. A method according to any one of claims 1 to 8 for producing opening means for the joint opening between two adjacent chambers of a container as a moulded body.

11. A molded article, in particular a film packaging, provided with localized opening means, At least two film portions (2) are joined to each other by a seal to form a seal seam, the film portion (2) or one or more partial areas (3, 4, 5, 6) of the film portion (2) are locally irradiated with an electron beam according to the method of any one of claims 1 to 8 before sealing, thereby forming the local opening means; Molded body.

12. A molded article, in particular a film packaging, comprising at least two mutually adjacent closed chambers, The chambers are separated from each other by a sealing seam formed by sealing two film portions (2), The film portion (2) or one or more partial regions (3, 4, 5, 6) of the film portion (2) have been locally irradiated with an electron beam according to the method of any one of claims 1 to 8 before the sealing. Molded body.

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