METHOD FOR PRODUCING DETERGENT PORTION UNITS

Description

[0001] The present invention relates to methods for producing portion units, in particular washing or cleaning agent portion units with at least one receiving chamber formed by a film material.

[0002] The packaging and distribution of consumer goods are subject to constantly changing demands. In the area of detergents and cleaning agents, for example, there has been a focus for some time on convenient dosing for consumers and simplifying the steps required to carry out a washing or cleaning process. Pre-portioned detergents and cleaning agents, such as foil pouches with one or more compartments for solid or liquid detergents or cleaning agents, offer a technical solution.

[0003] A relevant trend for the production of these film bags is the miniaturization of these bags. In addition to increased consumer acceptance due to easier handling, this development is driven by sustainability considerations, for example, with regard to the amount of packaging used.

[0004] The film bags described above are manufactured using multi-stage processes during which water-soluble film materials are formed into cavities, for example, through the action of heat and negative pressure, filled, and then sealed. While heating the film increases its plasticity, the force resulting from the negative pressure applied to the heated film causes it to stretch and plastically deform. In this process, the film is not stretched homogeneously across its surface; rather, areas of high stretch, for example, in the edge area of the cavity, alternate with areas of lower stretch. A film material with a homogeneous film thickness is thus transformed into a deformed film in the shape of a receptacle with a heterogeneous film thickness distribution. This heterogeneous film thickness distribution becomes more pronounced the more the original film material is deformed.The degree of deformation generally increases, for example, with the number of receiving chambers formed in the receiving container or their depth.

[0005] Among other factors, both the film thickness distribution and the absolute film thickness determine the haptic, optical, and mechanical properties of the film pouch. Film pouches with large differences in film thickness are often perceived as less appealing. Film pouches with a low minimum film thickness deform more easily under their own weight than corresponding film pouches with a higher film thickness and appear flabby. These film pouches withstand mechanical stress to a lesser extent and detach too quickly when exposed to water. The latter two properties are not only relevant for film pouches in the areas of production, transport, and storage, but also have a particular impact on product safety, for example in the event of accidental oral ingestion.

[0006] The European patent application EP 3 738 751 A1 describes a process for producing compact multi-chamber thermoformed bags with a reduced seal seam width.

[0007] Multi-chamber thermoformed bags with specific geometry and methods for their production are described in the patent applications US 2018 / 0282672 A1 and EP 1 375 637 A1.

[0008] The applications US 2022 / 0081656 A1, DE 20 19 295 A1 and EP 0 055 082 A2 relate to deep-drawing processes in which the deep-drawing film is heated unevenly before it is deformed.

[0009] DE 20 19 295 A1, EP 0 055 082 A2 disclose methods according to the preamble of claim 1. A heating device which is suitable for generating a temperature profile on a film web is the subject of European patent EP 3 078 478 B1.

[0010] To increase the homogeneity of the wall thickness in deep-drawing processes, the international application WO 2019 / 206448 A1 proposes a deep-drawing process in which a flat film is exposed to a temperature profile.

[0011] With the same objective, European patent application EP2298536 A2 and international patent application WO 2020 / 152044 A1 propose heating devices using heating devices with heterogeneous temperature distribution.

[0012] However, these previously described solutions require complex equipment and are only suitable to a limited extent for high throughputs. Furthermore, setting up and converting corresponding thermoforming lines is costly.

[0013] Against this technical background, the application was based on the object of providing a method for producing portion units which enables the efficient production of portion units with maximum stability and an appealing appearance and feel with minimal equipment expenditure and minimal use of film materials used for packaging.

[0014] A first subject of the application is a method for producing a portion unit with at least one filled receiving chamber surrounded by a film, comprising the steps a) Transporting a first film towards a heating device; b) Bringing the first film into contact with a surface of the heating device; c) Heating the first film by means of the heating device; d) Breaking the contact between the first film and the heating device; e) Forming the first heated film into the cavities of a deep-drawing die to form a receiving container with at least one receiving chamber; f) Filling the at least one receiving chamber; g) Optionally closing and separating the filled receiving containers to form the portion unit, wherein the surface area of the heating device which is brought into contact with the film has at least one depression and the at least one depression is covered in step b) by the partial areas of the first film which are formed into the cavity of the deep-drawing die in step e), wherein the outline of the opening area of the depression is modeled on the outline of the opening area of the cavity, characterized in that the outline of the opening area of the depression is obtained from the outline of the opening area of the cavity by a reduction factor of 0.6 to 0.8.

[0015] The process according to the invention enables the efficient production of detergent portion units. Due to the uniform thickness of the water-soluble film, the detergent portion units are characterized by high mechanical stability with minimal packaging, as well as an appealing feel and appearance.

[0016] In the process according to the invention, preferably water-soluble films are formed in a deep-drawing apparatus and combined with detergent preparations to form detergent portion units.

[0017] The water-soluble film may comprise one or more structurally different water-soluble polymers. Particularly suitable water-soluble polymers for the first water-soluble film are polymers from the group of (optionally acetalized) polyvinyl alcohols (PVAL) and their copolymers.

[0018] Water-soluble films for producing the portion unit are preferably based on a polyvinyl alcohol or a polyvinyl alcohol copolymer whose molecular weight is preferably in the range from 10,000 to 1,000,000 gmol -1< , preferably from 20,000 to 500,000 gmol -1< , particularly preferably from 30,000 to 100,000 gmol -1< and in particular from 40,000 to 80,000 gmol -1<. Preferred water-soluble films comprise at least 30 wt.%, preferably at least 50 wt.% and in particular at least 70 wt.% polyvinyl alcohol or polyvinyl alcohol copolymers.

[0019] The preparation of polyvinyl alcohol and polyvinyl alcohol copolymers generally involves the hydrolysis of intermediate polyvinyl acetate. Preferred polyvinyl alcohols and polyvinyl alcohol copolymers have a degree of hydrolysis of 70 to 100 mol%, preferably 80 to 90 mol%, particularly preferably 81 to 89 mol%, and especially 82 to 88 mol%.

[0020] Preferred polyvinyl alcohol copolymers comprise, in addition to vinyl alcohol, an ethylenically unsaturated carboxylic acid, its salt, or its ester. Particularly preferably, such polyvinyl alcohol copolymers contain, in addition to vinyl alcohol, sulfonic acids such as 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS), acrylic acid, methacrylic acid, acrylic esters, methacrylic esters, or mixtures thereof; among the esters, C 1-4 alkyl esters or hydroxyalkyl esters are preferred. Other suitable monomers include ethylenically unsaturated dicarboxylic acids, for example, itaconic acid, maleic acid, fumaric acid, and mixtures thereof.

[0021] Suitable water-soluble films for use in the portion units according to the invention are films sold by MonoSol LLC, for example, under the designation M8630, M8720, M8310, C8400, or M8900. Other suitable films include films designated Solublon ®< PT, Solublon ®< GA, Solublon ®< KC, or Solublon ®< KL by Aicello Chemical Europe GmbH, or the VF-HP films from Kuraray and the Hi-Selon series from Mitsubishi Chemical Corporation.

[0022] The first, preferably water-soluble film preferably has a thickness of 10 to 90 µm, preferably 30 to 60 µm.

[0023] The water-soluble films may contain additional active ingredients or fillers as well as plasticizers and / or solvents, especially water.

[0024] The group of other active ingredients includes, for example, materials that protect the detergent ingredients enclosed in the film material from decomposition or deactivation by light exposure. Antioxidants, UV absorbers, and fluorescent dyes have proven particularly suitable for this purpose.

[0025] Plasticizers that can be used include, for example, glycerin, ethylene glycol, diethylene glycol, propanediol, 2-methyl-1,3-propanediol, sorbitol or mixtures thereof.

[0026] To reduce its friction coefficient, the surface of the water-soluble film of the detergent dispenser can optionally be dusted with a fine powder. Sodium aluminosilicate, silicon dioxide, talc, and amylose are examples of suitable dusting agents.

[0027] The deep-drawing apparatus used in the process can be operated continuously or discontinuously. To increase process efficiency, a continuous process is preferred. In a particularly preferred embodiment of the process, the first, preferably water-soluble film is transported continuously in step a). With regard to process economy and process reliability, it is preferable to transport the first, preferably water-soluble film in step a) at a speed of 0.04 m / s, preferably above 0.08 m / s.

[0028] The surface area of the heating device surrounding the recess, with which the film is brought into contact in step b), is preferably flat. Particularly preferred materials for manufacturing the surface of the heating device with which the water-soluble film is in contact in step b) are ceramic or metal, in particular aluminum.

[0029] Preferred heating devices have a metallic surface, in particular a metallic surface comprising aluminum. Due to their thermally conductive properties, metallic heating device surfaces are preferred which consist of at least 70 wt. %, preferably at least 90 wt. %, particularly preferably at least 98 wt. %, and in particular entirely of aluminum.

[0030] The flat surface areas of the heating device can be structured to control heat transfer or to prevent adhesion. Surfaces structured in this way have, for example, visible or noticeable unevenness such as grooves. The structural elements naturally differ from the depressions in terms of their depth and width. In preferred structured surface areas, the maximum depth of the structural elements is less than 0.5 mm, preferably less than 0.2 mm and in particular less than 0.1 mm. The maximum depth corresponds to the maximum length of a line segment orthogonal to the opening surface between a point on the opening surface and a point on the bottom surface of the structural element.

[0031] Preferred heating devices have a circumferential border. The border encloses the flat surface area and the depression(s) formed in this surface area. Preferably, the border encloses at least four, preferably at least eight, and in particular at least sixteen depressions.

[0032] The border is used to space a film placed over the heating device from the heated surface. Contact between the film and the surface of the heating device only occurs through the application of targeted force, for example by applying a vacuum between the heating device surface and the film. As a result, the contact times between the heated surface and the film can be precisely controlled, even at high process speeds. Since the described spacing effect is less pronounced with a low border height, while the effect of the vacuum used is reduced with a high border height, the height of the border is preferably 0.5 to 2 mm, particularly preferably 0.8 to 1.2 mm. A border height of 1 mm is particularly preferred.

[0033] In summary, a preferred method variant is characterized in that the surface area of the heating device surrounding the recess is flat and is enclosed by a circumferential border with a height of 0.5 to 2 mm, preferably 0.8 to 1.2 mm.

[0034] With regard to the desired homogeneous film expansion, it has proven advantageous if the opening area of the at least one depression is smaller than the opening area of the cavity.

[0035] To achieve homogeneous film expansion, it is also advantageous to replicate the outline of the opening surface of the recess to the outline of the opening surface of the cavity. A replica is the two-dimensional shape of the opening surface of a recess that resembles the two-dimensional shape of the opening surface of the cavity, for example, with regard to the number of corners present.

[0036] It is particularly advantageous if the outline of the opening area of the recess is obtained from the outline of the opening area of the cavity by a reduction, preferably using reduction factors of 0.6 to 0.8.

[0037] Preferred recesses have an opening area with a maximum diameter of 10 to 40 mm, preferably 20 to 35 mm. The maximum depth of preferred recesses is 0.5 to 7 mm, preferably 0.8 to 4 mm. The maximum depth corresponds to the maximum length of a line orthogonal to the opening area between a point on the opening area and a point on the bottom surface of the recess.

[0038] The depressions can have different spatial shapes. Preferred depressions have at most one further edge in addition to the edge of the opening surface. It is further preferred if the depressions do not have any side surfaces orthogonal to the opening surface. Rather, depressions are preferred which are delimited exclusively by their opening surface and a base surface directly adjacent to the opening surface. Particularly preferred depressions have, for example, a hemispherical, compressed hemispherical, elongated hemispherical, or compressed and elongated hemispherical spatial shape. The base surface can be flattened, for example in the form of a region plane-parallel to the opening surface.

[0039] Preferred depressions are characterized by a bottom surface that slopes continuously from its edge to its lowest point. Of course, the depression may have more than one lowest point. For example, as described above, the depression may have a bottom surface that is partially plane-parallel to the opening surface. In such an embodiment, the bottom surface has a continuous slope between the edge of the depression and the edge of the plane-parallel region of the bottom surface.

[0040] The gradient can be linear or non-linear. Both the absolute gradient and its relative gradient have proven to be relevant for the film thickness homogeneity achieved. Preferred depressions have a bottom surface that slopes continuously from their edge to their deepest point, the gradient of which is linear for at least 10%, preferably 30%, of the shortest distance from the edge to the deepest point. Process variants that use depressions that have a bottom surface that slopes continuously from their edge to their deepest point, the gradient of which is linear for 10 to 90%, preferably 30 to 80%, of the shortest distance from the edge to the deepest point have proven advantageous.

[0041] It is preferred if the depression has a bottom surface which slopes continuously from its edge to its deepest point, the gradient of which changes at least at one point over the shortest distance from the edge to the deepest point.

[0042] Preferably, the depression has a bottom surface which slopes continuously from its edge to its lowest point, the gradient of which on the shortest distance from the edge to the lowest point is 10 to 50%, preferably 15 to 40%, over the entire distance.

[0043] The volume of preferred wells is 1 to 8 ml, preferably 1 to 6 ml.

[0044] The ratio of the maximum depth of the depression in step b) to the maximum depth of the cavity in step e) is preferably 2:3 to 1:5, particularly preferably 1:2 to 1:4. A corresponding ratio has proven advantageous both with regard to the homogeneity of the film thickness distribution and with regard to process control.

[0045] The method according to the invention is particularly suitable for producing portion units with complex geometries or for portion units with more than one receiving chamber. In a preferred embodiment of the method, the portion unit therefore has at least two, preferably at least three, and in particular at least four receiving chambers, wherein the heating device has a number of recesses corresponding to the number of receiving chambers, which recesses are covered in step b) by the partial regions of the first film, which are formed in step e) into the cavity of the deep-drawing die to form the at least two, preferably at least three, and in particular at least four receiving chambers.

[0046] If portion units are produced with two or more receiving chambers, the receiving chambers may be identical in terms of their spatial shape or dimensions, but may also differ. The advantages of the method according to the invention with regard to achieving homogeneous film thickness distributions are particularly evident in the production of portion units using heating devices that have at least two recesses that differ in their maximum depth.

[0047] The surface of the heating device is preferably flat between two adjacent recesses belonging to a portion unit. The minimum distance between two such adjacent recesses is preferably 0.5 to 4 mm, preferably 1 to 3 mm.

[0048] In a preferred embodiment, the two, three, or four receiving chambers, and consequently also the recesses associated with the receiving chambers, are arranged to at least partially enclose one another. This procedure is implemented, for example, in the production of portion units with at least two, preferably at least three, and in particular at least four receiving chambers, one of which forms a center around which the remaining chambers are arranged rotationally symmetrically.

[0049] As stated above, the heating device preferably has a metallic surface. This preferably metallic surface, in turn, has recesses that enable the efficient production of portion units with maximum stability and an appealing appearance and feel, with minimal equipment expenditure and minimal use of film materials used for packaging.

[0050] These advantageous properties of the method according to the invention can be enhanced by at least partially coating the surface of the heating device. It is particularly advantageous if the surface of the heating device is at least partially coated in the region of the depression. Such a coating, like the depressions in the surface, influences the film thickness distribution of the produced receptacles. In this context, it has proven advantageous to fully coat the surface of the heating device in the region of the depression(s).

[0051] The coating may extend to the surface of the heating device in the region of the depression(s) and the edge region surrounding the depression.

[0052] The coating of the heater surface in the region of the recesses necessarily leads to at least partial filling of the recess volume. In variants of the method according to the invention, the at least one recess is filled to at least 60 vol.%, preferably to at least 80 vol.%, and in particular completely with a coating material.

[0053] The coating may cover 5 to 80%, preferably 10 to 70% and in particular 20 to 50% of the surface area of the heating device which is brought into contact with the film in step b).

[0054] Suitable coating materials include metals and polymers, especially rubber and silicone. Silicone coatings are particularly preferred due to their heat resistance and moldability.

[0055] Preferred coating agents have a lower thermal conductivity and / or a lower heat transfer coefficient than the heater surface.

[0056] The thickness of the coating is preferably 100 to 4000 µm, particularly preferably 200 to 2000 µm.

[0057] Any coatings can be bonded to the base surface in a variety of ways. Adhesive bonds are suitable for creating a permanent and temporally stable bond between the heater surface and the coating agent. Clamp or plug connections, on the other hand, are preferably used in cases where rapid replacement of the coating agent is desired, for example, due to wear or to change the process parameters.

[0058] For the film thickness distribution of the process product, it has proven advantageous if the coating in step b) is in contact with the surface portion of the water-soluble film, which is formed into the cavity of the deep-drawing tray in step e).

[0059] In a preferred process variant, the first film is brought into contact with the heating device on only one side in step b). Compared to processes using two heating devices, the process according to the invention not only requires less equipment, but also allows for a more compact design of the production line.

[0060] Preferably, in step b), the upper side of the film is brought into contact with the heating device. The upper side is the side of the film that is still spatially oriented upwards. For this purpose, the heating device is preferably lowered toward the film in step b).

[0061] To reduce the process time and ensure reproducible contact between the first water-soluble film and the surface of the heating device, the film is brought into contact with the heating device in step b) by means of a negative pressure. Furthermore, it is preferred to maintain contact between the film and the heating device by maintaining a negative pressure. The level of a corresponding negative pressure, which is built up between the heating device and the film in step b), is preferably 200 to 800 mbar and in particular 400 to 700 mbar.

[0062] To support the uniform development of a negative pressure between the heating device and the water-soluble film, the surface of the heating device preferably has holes through which gas located between the heating device and the film can be removed. These holes are preferably located 60%, preferably 90%, especially 95%, and most preferably completely outside the recesses.

[0063] In step c), the film is preferably heated for a period of 0.5 to 7 seconds, preferably 1 to 6 seconds and in particular 2 to 5 seconds.

[0064] The metallic surface of the heating device preferably has a temperature in the range of 23 to 150°C, preferably 80 to 135°C. It is particularly preferred if the surface of the heating device in the region of the elevation(s) with which the water-soluble film is in contact in step b) has a temperature in the range of 90 to 150°C, preferably 110 to 135°C.

[0065] To further equalize the expansion factors of the different sections of the water-soluble film forming the receiving container, it has also proven advantageous if the at least one elevation in step c) is in contact with each surface section of the water-soluble film that forms the edge region of the receiving chamber(s) of the receiving container. For the same reasons, it is preferred that the surface sections of the water-soluble film that form the bottom region of the receiving chamber(s) of the receiving container are not in contact with the heating device in step c).

[0066] In order to increase the process efficiency and to increase the film thickness homogeneity in the process according to the invention, it has proven advantageous if the film in step c) is located between the heating device and the deep-drawing die used in step e), preferably below the heating device and above the deep-drawing die used in step e), wherein the distance between the surface of the heating device and the deep-drawing die is preferably less than 10 mm, preferably less than 5 mm, in particular 0.1 to 2 mm and particularly preferably 0.2 to 1 mm.

[0067] In step d), the contact between the first water-soluble film and the surface of the heating device is eliminated. For this purpose, any negative pressure acting between the heating device and the film is eliminated. In a particularly preferred embodiment of the method, in step d), a negative pressure previously created between the heating device and the film is eliminated, and the heating device is raised simultaneously or subsequently.

[0068] At the beginning of step e), the film preferably has a temperature above its glass transition temperature.

[0069] In step e), the film is molded into the cavity of a deep-drawing die. For this purpose, a negative pressure is created between the film and the deep-drawing die, preferably for a period of 0.5 to 7 seconds, preferably 1 to 5 seconds. This negative pressure created between the film and the deep-drawing die is preferably 100 to 600 mbar, and in particular 200 to 400 mbar.

[0070] During molding into the cavity of the deep-drawing die, the surface area of the water-soluble film is preferably increased by at least 80%, preferably by at least 120%, in particular by 120 to 300%, and particularly preferably by 180 to 260%. Accordingly, following step e), the film has a total stretch factor of preferably at least 1.2, preferably from 1.2 to 3.0, and in particular from 1.8 to 2.6. At the same time, the maximum local stretch factor of the water-soluble film following step e) is preferably from 1.8 to 4, particularly preferably from 2 to 2.8.

[0071] It is particularly preferred if the water-soluble film is molded in step e) to form a receiving container with at least two, preferably at least three and in particular at least four receiving chambers.

[0072] The receiving chamber(s) formed in step e) preferably have a filling volume of 2 to 8 ml, particularly preferably 3 to 7 ml. The filling volume of the receiving container in step e) is preferably 2 to 50 ml, more preferably 10 to 40 ml, and in particular 13 to 25 ml.

[0073] In preferred process variants in which the receiving container has at least two, preferably at least three and in particular at least four receiving chambers, the ratio of the volume of the largest receiving chamber to the volume of the smallest receiving chamber is 4:1 to 1:1, preferably 3:1 to 1:1.

[0074] For reasons of process efficiency, the method according to the invention is designed such that not just a single detergent portion unit is produced in one process run, but rather a plurality of detergent portion units are produced in parallel. Preferably, in step e), a sheet-like structure with at least 14, preferably at least 20, receptacles is formed.

[0075] In this sheet-like structure, the receiving containers are preferably arranged in rows. With regard to subsequent filling, the sheet-like structures formed in step e) are preferably arranged in rows that are orthogonal to the transport direction of the water-soluble film.

[0076] In an alternative embodiment, in step e) a sheet-like structure is formed in which the receiving containers are arranged in rows which run orthogonally to the transport direction of the water-soluble film and are offset from one another by one third of the width of a receiving container, preferably by half the width of a receiving container.

[0077] In the sheet-like structure, the receiving containers are preferably arranged such that each receiving container is adjacent to at least one intermediate region, which in turn is surrounded by three receiving containers.

[0078] At least one receiving chamber of the receiving container is filled in step f). Solid and liquid detergents or cleaning agents are suitable for filling.

[0079] Particularly in cases where the added detergents or cleaning agents are not adhesively bonded to the water-soluble film material, as may be the case with melts, for example, the filled receiving chamber of the receiving container is sealed. Corresponding processes, in which the receiving chamber of the receiving container is filled in a further step f) and the filled receiving chamber is sealed in a subsequent step g) using a second water-soluble film, are preferred with regard to product aesthetics and handling. Examples

[0080] A water-soluble polyvinyl alcohol film (88 µm thick) was heated using various heating devices and subsequently formed into a droplet-shaped receiving chamber by applying negative pressure. The heating plate temperature was 120°C in each case. With the exception of the heating device, the process parameters used in the experiments were identical.

[0081] The following two heating devices were used: Heating device 1: completely flat heating plate (aluminium) Heating device 2: heating plate (aluminium) with a recess (maximum depth 1 mm) whose outline is modeled on the drop-shaped receiving chamber with a reduction factor of 0.8

[0082] Following the deep-drawing process, the film thickness in the receiving chambers was determined using optical methods (film thickness analyzer) along a cross-section orthogonal to the longitudinal axis of the droplet. The film thickness was measured at nine equidistant measuring points along the cross-section. Film thickness ([µm])

[0083] 1 2 3 4 5 6 7 8 9 Heating device 1 34,6 29,6 27,1 24,4 25,9 24,7 24,1 27,1 33,3 Heating device 2 36,6 34,1 32,0 35,0 35,0 34,6 25,9 33,7 43,8

[0084] The receiving chambers obtained using the recessed heating plate are characterized by a higher film thickness despite the identical starting film. Portion units obtained by filling them with a liquid detergent and subsequently sealing them with a second water-soluble film exhibited improved mechanical stability.

Claims

1. A method of manufacturing a portion unit having at least one filled receiving chamber surrounded by a film, comprising the steps of a) Transport of a first film in the direction of a heating device; b) Bringing the first film into contact with a surface of the heating device; c) Heating the first film using the heating device; d) Remove the contact between the first film and the heating device; e) Moulding the first heated film into the cavities of a thermoforming die, forming a receiving container with at least one receiving chamber; f) Filling of at least one receiving chamber; g) If necessary, closing and separating the filled receiving containers while forming the portion unit, wherein the surface region of the heating device, which is brought into contact with the film, has at least one recess and the at least one recess is covered in step b) by the partial regions of the first film, which are moulded into the cavity of the thermoforming die in step e), wherein the outline of the opening surface of the recess is modelled on the outline of the opening surface of the cavity, characterised in that the outline of the opening surface of the recess is obtained from the outline of the opening surface of the cavity by a reduction factor of 0.6 to 0.8.

2. Method according to claim 1, wherein the recess has a hemispherical, compressed hemispherical, stretched hemispherical or compressed and stretched hemispherical spatial shape.

3. Method according to any one of the preceding claims, wherein the recess has a maximum depth (measured as the orthogonal distance between the opening surface and the bottom surface of the recess) of from 0.5 to 7 mm, preferably from 0.8 to 4 mm.

4. Method according to one of the preceding claims, wherein the ratio of the maximum depth of the cavity in step b) to the maximum depth of the cavity in step e) is preferably 2:3 to 1 to 5, particularly preferably 1:2 to 1:4.

5. Method according to any one of the preceding claims, wherein the recess has a continuously sloping bottom surface from its edge to its deepest point.

6. Method according to one of the preceding claims, wherein the portion unit has at least two, preferably at least three and in particular at least four receiving chambers, wherein the heating device has a number of recesses corresponding to the number of receiving chambers, which recesses are covered by the partial regions of the first film in step b), which are moulded into the cavity of the thermoforming die in step e), forming at least two, preferably at least three and in particular at least four receiving chambers.

7. Method according to any one of the preceding claims, wherein the film is selected from the group of water-soluble films.

8. Method according to one of the preceding claims, wherein the surface of the heating device is at least partially coated in the region of the recess.

9. Method according to one of the preceding claims, wherein the surface of the heating device is fully coated in the region of the recess(es).

10. Method according to one of the preceding claims, wherein the film in step c) is located below the heating device and above the thermoforming die used in step e) and the distance between the surface of the heating device and the surface of the thermoforming die is less than 10 mm, preferably less than 5 mm, in particular 0.1 to 2 mm and particularly preferably 0.2 to 1 mm.

11. Method according to any one of the preceding claims, wherein the first water-soluble film is brought into contact with the heating device on only one side in step b).

12. Method according to any one of the preceding claims, wherein the heating device has a metallic surface and the metallic surface of the heating device has a temperature in the range from 23 to 150°C, preferably from 80 to 135°C.