Method for manufacturing a packaging container, said packaging container, and curling tool

Abstract

The present invention relates to a method for forming a paperboard packaging container (1) from a rectangular body blank (2), the method comprising the steps of: a) preparing a body blank having a first side edge and a second side edge; and b) forming a tubular container body (2) from the body blank, the tubular container body (2) having a first end (3) with a first end opening (4) formed therein, a second end (5) with a second end opening (6) formed therein, and a width (width) (length ... a container body wall (7) extending between the body blank and the mouth (6), the container body wall (7) having an inner surface (8) and an outer surface (9); c) sealing together a first side edge and a second side edge of the body blank; and d) closing the first end opening (4) by forcing a paperboard disk (12) into the first end opening (4), the paperboard disk (12) having a peripheral flange bent toward the first end (3) of the tubular container body (2) in a height direction (H) of the paperboard packaging container (1). (13), the peripheral flange (13) of the paperboard disc (12) being sealed to the inner surface (8) of the container body wall (7); and e) pressing the first end (3) of the tubular container body (2) into the curl-forming portion (31) of the curling tool (30), the curl-forming portion (31) having an inner tool surface (32) with three or more spaced apart projections (33) to curl the first end (3) of the container body wall (7) inwardly and form a first curl having a curved edge portion (14a) and an inner portion (14b). forming a first curled edge (14) and providing three or more spaced indents (15) around the circumference of the tubular container body (2) on an inner portion (14b) of the first curled edge (14), the indents (15) being formed by spaced protrusions (33) on the tool inner surface (32); f) filling the paperboard packaging container (1) with bulk solids; and g) closing the second end opening (6), wherein step g) and the subsequent step f) are performed alternately after step c).

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing paperboard packaging containers, paperboard packaging containers manufactured by the method, and a curling tool. [Background technology]

[0002] In the field of disposable containers for products such as infant formula, cigarettes, and detergents, there is a continuing need to reduce the carbon footprint of such products by making the containers recyclable and minimizing resource utilization for disposable containers. The disposable container in this invention is a composite container having a tubular container body made from a laminated sheet material with a carton layer, i.e., a layer made primarily of cellulosic fibers. The upper and lower edges of the package include plastic rims connected to the edges of the package. This gives the package a pleasant, neat appearance and provides good wear resistance at the top or bottom of the package. Alternatively, the bottom of the package can be made from a folded end of the tubular container body or a bottom disk attached to the tubular container body at its lower end. However, the appearance of such a package is somewhat unattractive, and the wear resistance at the bottom end of the package is poor.

[0003] To improve the appearance and stability of the bottom or top end of the package container, the ends of the container body wall are curled inward to form a curled bottom or top edge. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2017 / 180056 Summary of the Invention [Problem to be solved by the invention]

[0005] SUMMARY OF THE INVENTION An object of the present invention is to improve curled edges in paperboard packaging containers. [Means for solving the problem]

[0006] The above-mentioned object is achieved by a method for forming a paperboard packaging container according to claim 1, a paperboard packaging container according to claim 4, and a curling tool according to claim 13.

[0007] In a first embodiment, the present invention provides a method for producing a medicament for the treatment of a pulmonary arthritis, comprising: 1. A method for forming a paperboard packaging container from a rectangular body blank, comprising: The method is a) providing a body blank having a first side edge and a second side edge; b) forming a tubular container body from the body blank, the tubular container body having a first end with a first end opening, a second end with a second end opening, and a container body wall extending in a height direction of the paperboard packaging container between the first end opening and the second end opening, the container body wall having an inner surface and an outer surface; c) sealing together the first and second side edges of the body blank; d) closing the first end opening by forcing a paperboard disk into the first end opening, the paperboard disk having a peripheral flange bent in a height direction of the paperboard packaging container toward the first end of the tubular container body, the peripheral flange of the paperboard disk being tightly attached to the inner surface of the container body wall; e) forcing the first end of the tubular container body into a curling portion of a curling tool, the curling portion having an inner tool surface with three or more spaced protrusions, thereby curling the first end of the container body wall inward to form a first curled edge having a curved edge portion and an inner portion, and providing three or more spaced indents in the inner portion of the first curled edge along the circumference of the tubular container body, the indents being formed by the spaced protrusions of the inner tool surface; f) filling the paperboard packaging container with bulk solids; g) closing the second end opening; It is equipped with After step c), step g) and the subsequent step f) are performed alternately.

[0008] The first curled edge may be referred to as the curled bottom edge, meaning that the first end opening is the bottom end opening and the paperboard disc is the bottom disc.

[0009] The first curled edge may be referred to as the curled top edge, meaning that the first end opening is the top end opening and the paperboard disc is the top disc.

[0010] A stable top and / or bottom container edge is important to enhance the stackability of the package during shipping and storage.

[0011] The method for manufacturing a paperboard container according to the present invention can further reduce the height of the contact surface of the curled edge, i.e., the height of the surface that comes into contact with, for example, a shelf. Because the curled edge is made sharper and bent than in conventional curling operations, the curled edge is more distinctive and compact, thereby reducing the risk of soiling or damaging the curled bottom edge. The stability of the package is also improved. In the case where the first edge is the upper end, the upper edge is more distinctive and compact, improving the stackability and abrasion resistance of the edge. The distinctive and compact edge also improves the appearance of the package.

[0012] Instead of adding plastic components to the packaging container by attaching a plastic rim to the bottom and / or top edges of the packaging container, the bottom and / or top edges of the packaging container can be stabilized by folding or wrapping the bottom / top ends of the container body wall inward to form curled bottom and / or top edges. This eliminates the need for plastic components that make the packaging container difficult to recycle. However, the inventors of the present application have discovered that the curled bottom and / or top edges of prior art packaging containers are not ideally aligned due to the construction of the containers using relatively stiff and thick paperboard materials. Furthermore, the inventors have discovered that because the curled edges are not properly aligned, they tend to recover somewhat after formation.

[0013] To form the curled edge, the first end of the tubular container body is pressed into a curl-forming portion, such as a circumferential track, of a curling tool. The first end of the tubular container body bends by following the outer surface of the curl-forming portion until it reaches the bottom surface, then bends inward by following the contour of the bottom surface, and folds over itself while contacting the inner surface of the tool. By using the curling tool of the present invention to press the inner portion of the curled edge against the protrusions, the fibers of the carton structural layer are broken, reducing the stiffness of the paperboard material and making the curl easier to control, thereby creating a more distinctive curled edge. Three or more protrusions spaced apart on the inner surface of the tool form three or more indents spaced apart around the circumference of the tubular container body on the inner portion of the first curled edge. In addition to breaking the fiber structure, the indent flattens the inner portion of the curled edge, preventing the curled edge from uncurling over time and forming a neatly curled bottom edge around the package container.

[0014] The curl forming portion has an inner tool surface on which four or more spaced apart protrusions are formed, or five or more spaced apart protrusions are formed. The curl forming portion has an inner tool surface on which six or more spaced apart protrusions are formed, for example, 8 to 50 spaced apart protrusions are formed.

[0015] The curl forming portion is a U-shaped track, the outer shape of the curl forming portion has a footprint substantially the same as the first end of the container body so that the first end of the container body fits into the curl forming portion, and the inner surface of the tool is the inner surface of the curl forming portion. The term "substantially the same" is intended to allow for a difference of 0 mm to 3 mm between and along the footprint of the first end of the container body and the footprint of the curl forming portion.

[0016] As used herein, paperboard material is a sheet material made primarily from cellulose or paper fibers. The sheet material may be provided in the form of a continuous web or as individual sheets of material. The paperboard material may be a single-ply or multi-ply material, such as a laminate comprising one or more layers of material, such as polymeric films, coatings, and metal foils. The polymeric films and coatings may include or consist of thermoplastic polymers. The paperboard material may be coated, printed, embossed, etc., and may contain fillers, pigments, binders, and other additives known in the art. The paperboard material disclosed herein may also be referred to as corrugated board or carton material.

[0017] In step c), both the first and second side edges of the body blank are sealed by sealing the border areas along the first and second side edges using a sealing strip and / or gluing or welding. Alternatively, both the first and second side edges may be sealed by overlapping the edges and using gluing or welding. In each of these two variants, the preferred method is welding of the edges. The welding may be high-frequency induction welding.

[0018] The tubular container body may be formed to have three or more wall portions connected via corners. Alternatively, the tubular container body may be formed to have four or five wall portions connected via corners, each having a corner. Each wall portion may have one or more indents spaced apart on the inner portion of the first curled edge, for example, two, three, four, or five indents spaced apart on the inner portion of the first curled edge. The corners may not have any indents. The corners of the tubular container body may be curved corners.

[0019] Alternatively, the tubular container body may have a circular cross section. The tubular container body may also have a generally square, triangular, or elliptical cross section. Generally square and triangular cross sections include cross sections with curved corners.

[0020] When the side edges are sealed by a sealing strip, the side edges are preferably welded to the inner surface of the tubular container body by high-frequency induction welding. Container components, such as the top seal, bottom disk, and top rim, are attached by an attachment unit comprising a welding unit, such as a high-frequency welding unit, configured to secure the components to the tubular container body during the manufacture of the composite container. The welding unit includes an induction welding energy generator for softening or melting weldable layers forming part of the tubular container body and / or the attached container components. Alternatively, the sealing strip may be fixedly attached to the inner surface of the tubular container body, in which case the attachment unit includes an adhesive unit. Of course, the sealing strip may also be attached by any other suitable means. For example, the sealing strip may be made of a laminate film including an aluminum layer, a polyethylene layer, and a polyester layer.

[0021] The paperboard disk is attached to the tubular container body by welding a peripheral flange of the paperboard disk to the inner surface of the tubular container body, the peripheral flange being formed by folding an edge portion of the paperboard disk out of the plane of the paperboard disk to coincide with the inner surface of the tubular container body, and the paperboard disk is attached spaced from the first edge of the tubular container body to curl the first end to form the second curled edge.

[0022] Step e) includes folding or rolling the second end of the container body wall inward to cover the peripheral flange of the paperboard disk. This improves the stability of the first curled edge because the lateral thickness of the curled edge is increased. Furthermore, because the inner portion of the curled edge is provided over the peripheral flange, the edge of the peripheral flange is covered by the curled edge and does not interfere with the bottom or top edges of other packaging containers when stacked. This improves the stackability of the paperboard packaging container.

[0023] The method may include step h) of curling the second end of the container body wall inward by forcing the second end of the tubular container body into a curl-forming portion of a curling tool to form a second curled edge having a bent edge portion and an inner portion, and providing three or more indents spaced apart along the circumference of the tubular container body in the inner portion of the first curled edge, wherein the indents are formed by spaced apart protrusions on the inner surface of the tool.

[0024] For the method for forming a paperboard packaging container having both a first curled edge and a second curled edge, the step of forming the first curled edge includes all of the features disclosed for the method for forming the second curled edge. Similarly, for the packaging container including both a second curled edge and a first curled edge, the first curled edge includes all or some of the features disclosed for the second curled edge.

[0025] In a second embodiment, the present invention relates to a paperboard packaging container for bulk solids. The paperboard packaging container is formed by utilizing the method described above. The packaging container includes a tubular container body made of a laminated sheet material including a carton substrate layer, a container bottom, and a container lid. The tubular container body extends in the height direction of the paperboard packaging container from a first end to a second end, and the tubular container body includes a container body wall. The container body wall has an inner surface facing toward an inner compartment of the paperboard packaging container, an outer surface facing the opposite side of the inner compartment, a first edge, and a second edge, and the first end opening is closed by a paperboard disk. A paperboard disk is curved in height toward a first end of the paperboard packaging container and has a peripheral flange attached to an inner surface of the container body wall. The first end of the container body wall is curled inward to provide a first curled edge having a rim portion and an inner portion. The container body wall is located within the inner portion of the first curled edge, which includes three or more indents spaced around the circumference of the tubular container body.

[0026] The depth of each of the three or more indentations, measured perpendicular to the height of the package, is at least 0.2 mm, such as at least 0.5 mm, and may be up to 6 mm, from the inner surface of the curled portion of the curled edge.

[0027] The inner portion of the curled edge has a height of 2 mm to 30 mm measured in the height direction from the edge portion of the curled edge and the distal edge of the inner portion of the curled edge, and the distal edge of the inner portion corresponds to the second lateral edge of the main body blank.

[0028] The tubular container body is formed to have three or more wall portions connected via corners. The tubular container body may be formed to have four or five wall portions connected via corners. Each wall portion has one or more spaced indents disposed on the inner portion of the first curled edge, for example, two, three, four, or five indents disposed on the inner portion of the first curled edge. The corners may not have indents. The corners of the tubular container body are curved corners.

[0029] Alternatively, the tubular container body has a circular cross section, or the tubular container body has a generally square, triangular, or elliptical cross section.

[0030] If the first end opening is a bottom end opening, the paperboard disc is the bottom disc and the first curled edge is the curled bottom edge.

[0031] If the first end opening is the top end opening, the paperboard disc is the top disc and the first curled edge is the curled top edge.

[0032] The second end of the container body wall is curled inward to form a second curled edge having an edge portion and an inner portion, and the inner portion of the second curled edge has three or more indents spaced apart along the circumference of the tubular container body.

[0033] An example of a packaging container suitable for having both a curled top end and a curled bottom end is disclosed in U.S. Patent No. 5,623,999. The packaging container in U.S. Patent No. 5,623,999 is of the insert-lid type and is formed from a paperboard top disk and a container body wall, with a circumferential cut at least partially along the circumference of the container body so that an upper portion forming the insert-lid can be separated.

[0034] The composite container described herein includes a top seal member attached to the inside surface of the tubular container body spaced from the top end of the tubular container body.

[0035] In step g), the packaging container is provided with a top seal member. The top seal member may be an openable or peelable top seal member, meaning that the top seal member can be fully or partially removed by a user to provide initial access to the interior compartment of the composite container by breaking the seal between the top seal member and the inner surface of the tubular container body, or by tearing or otherwise breaking the top seal member itself.

[0036] The top seal member is airtight or gas-permeable. The airtight top seal member is made of any material or combination of materials suitable for providing an airtight seal to the compartment bounded by the sealing membrane, such as aluminum foil, silicone-coated paper, carton, plastic film, or laminates thereof. An airtight top seal member is particularly advantageous when the contents of the composite container are susceptible to air and / or moisture.

[0037] The top seal member is attached to the tubular container body by welding the peripheral flange of the top seal member to the inner surface of the tubular container body. In the present invention, the top seal member is typically a flexible member made from a laminate, including a guide layer, such as one or more layers of metal foil, e.g., aluminum foil, and an outer layer of a thermoplastic polymeric material. The peripheral flange is formed by folding an edge portion of the top seal member out of the plane of the top seal member to conform to the inner surface of the tubular container body. The top seal member is attached spaced from the upper edge of the tubular container body to attach the top rim above the top seal member. If the composite container includes a scoop, leaflet, or other auxiliary item, the top seal member is attached spaced from the upper edge of the tubular container body by a sufficient distance to accommodate the item in the space formed between the top seal member and the inner surface of the lid.

[0038] Depending on whether the top seal member is attached or applied from the upper end of the tubular container body or from the bottom end of the tubular container body, the flange of the top seal member that is joined to the inner surface of the tubular container body is oriented upward toward the container opening or downward toward the point end of the composite container.

[0039] The top seal member is configured as a shipping seal and is provided in addition to the retractable lid to keep the contents of the composite container fresh and protected from contamination until the consumer first opens the composite container.

[0040] Peelable top seal members are typically in the form of a flexible foil that includes a gripping tab or other gripping device for easy removal of the top seal member.

[0041] The lid of the composite container of the present invention may be part of a lid component, which includes a top rim and a lid portion.

[0042] Alternatively, the lid may be a separate part of the composite container, such as a bayonet lid, that can be completely removed when the composite container is opened.

[0043] If the lid is part of the lid assembly, the lid is connected to the top rim via a hinge. The hinge may be an integral hinge, i.e., a flexible connection between the lid and the top rim or frame structure. An integral hinge may be integrally formed with the lid and / or the top rim or frame structure, or the frame structure may be a separately formed element attached to the lid and to the top rim or frame structure. Alternatively, the hinge may be a two-part hinge, with a first hinge portion located on the lid and a second hinge portion located on the top rim or frame structure.

[0044] The composite containers described herein are containers for dry or moist goods, sometimes referred to as "bulk solids." Such goods are non-liquid, generally particulate, materials that can be poured from a can, scooped, or dispensed by hand. The containers are disposable containers that are discarded after the contents of the container are emptied.

[0045] "Particulate material" or "particulate product" broadly includes any material in the form of particles, granules, grounds, plant pieces, short fibers, flakes, seeds, fragments, etc. Particulate products suitable for packaging in the composite containers described herein are generally flowable, non-liquid products such that the desired amount of packaged product can be poured, scooped, or manually removed from the composite container.

[0046] The composite containers described herein are intended for digestive or consumable products such as, for example, infant formula, coffee, tea, rice, flour, sugar, rice, peas, beans, lentils, cereals, soup powder, custard powder, pasta, snacks, etc. Alternatively, the packaged product may be non-food, such as, for example, tobacco, detergent, dishwashing powder, fertilizer, chemicals, etc.

[0047] The paperboard packaging container of the second embodiment is formed by the method for forming the paperboard packaging container of the first embodiment.

[0048] In a third embodiment, the present invention relates to a curling tool for forming a curled edge on a paperboard packaging container. The curling tool is a curling plate having a track-shaped curl-forming portion having a closed loop shape configured to receive an end of a tubular container body. The curl-forming portion has an inner surface, an outer surface, and a bottom surface. The curling plate has a first major surface that faces the paperboard packaging container when forming the curled edge. The curl-forming portion is disposed on the first major surface and has a depth extending from the first major surface to the bottom surface of the curl-forming portion. The inner surface has three or more protrusions spaced around the periphery of the curl-forming portion.

[0049] When the protrusion is disposed on the curl-forming portion when forming the curled edge, the protrusion extends into the curl-forming portion in a direction perpendicular to the height direction of the package container.

[0050] When viewed in cross section, the curl forming portion is a U-shaped track having approximately the same installation area as the first end of the container body so that the first end of the container body is fitted into the U-shaped track, and the inner surface of the tool is the inner surface of the U-shaped track.

[0051] The curl forming portion has an inner tool surface having four or more spaced apart protrusions. The curl forming portion has an inner tool surface having six or more spaced apart protrusions, for example, 8 to 50 spaced apart protrusions.

[0052] Three or more protrusions protrude 0.2 mm or more from the inner surface of the curl forming part.

[0053] Three or more protrusions protrude from the inner surface of the curl forming portion by 0.5 mm or more or 1.5 mm or more.

[0054] The depth of the curl forming portion is set to 5 mm to 40 mm.

[0055] The depth of the curl forming portion is set to 5 mm to 30 mm.

[0056] Three or more protrusions have a predetermined diameter and are arranged with a spacing between adjacent protrusions that corresponds to at least the diameter of the protrusions. Optionally, the spacing between adjacent protrusions is 5 mm to 50 mm. Optionally, the spacing between adjacent protrusions is 5 mm to 20 mm.

[0057] Optionally, three or more of the protrusions have a diameter of between 5mm and 20mm.

[0058] The three or more protrusions have a diameter of 2 mm to 10 mm.

[0059] The three or more protrusions are formed by studs disposed on the curl-forming tool along the periphery of the curl-forming portion.

[0060] Additionally, three or more protrusions are aligned horizontally with one another along the circumferential direction of the curl-forming portion.

[0061] The curling tool in the third embodiment is a curling tool for use in the method for forming the paperboard packaging container in the first embodiment and for providing the paperboard packaging container in the second embodiment.

[0062] The invention will now be further described by way of non-limiting example with reference to the accompanying drawings, in which: [Brief explanation of the drawings]

[0063] [Figure 1] 2 shows a tubular container body and a curling tool according to the present invention before the curled edge is formed. [Figure 2] 10 shows how the first end of the tubular container body is pressed into the curl-forming portion of the curling tool. [Figure 3] 1 shows how the ends of the container body wall are curled inward to form the curled edge. [Figure 4]1 shows how the ends of the container body wall are curled inward to form the curled edge. [Figure 5] 1 shows how the ends of the container body wall are curled inward to form the curled edge. [Figure 6] 1 shows a package container having curled edges according to the present invention. [Figure 7] 10 represents an optional step for forming a second curled edge. [Figure 8] 1 shows a package container according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0064] It should be noted that the drawings are schematic and that individual components, such as material layers, are not necessarily drawn to scale. The steps in the method for forming the packaging container and the packaging container shown are exemplary only and should not be construed as limiting the scope of the present invention. Accordingly, the scope of the present invention is determined solely by the scope defined by the claims.

[0065] 1 illustrates a step in a method for forming a paperboard packaging container from a tubular container body 2. The tubular container body 2 has a first end 3 with a first end opening 4, a second end 5 with a second end opening 6, and a container body wall 7 extending in a height direction H between the first end opening 4 and the second end opening 6. The container body wall 7 has an inner surface 8 and an outer surface 9, and a first edge 10 and a second edge 11. In a first step (not shown) of the method, the tubular container body 2 is formed by providing a body blank having a first side edge and a second side edge and sealing the first side edge and the second side edge of the body blank together to form the tubular container body. The first end opening 4 is closed by forcing a paperboard disk 12 into the first end opening 4 (this method step is not shown). The paperboard disk 12 has a peripheral flange 13 that is bent in the height direction H of the tubular container body 2 toward the first end 3 of the container body 2. The peripheral flange 13 of the paperboard disk 12 is in intimate contact with the inner surface 8 of the container body wall 7. In Figure 1, the tubular container body 2 has a rectangular cross-section consisting of a front wall portion 18, a rear wall portion 19, and two side wall portions 20, 21, which are connected via curved corners 22, 23, 24, 25. It should be noted that, as described herein, the cross-section of the packaging container is arbitrary, provided that it is appropriate.

[0066] FIG. 1 also shows a curling tool 30 for forming the curled edge 14 (shown in FIG. 6) on a paperboard packaging container. The curling tool 30 is a curling plate having a curl-forming portion 31 in the form of a U-shaped track having a closed loop shape configured to receive the first edge 3 of a tubular container. In FIG. 1, the curl-forming portion has a modified rectangular shape with a curved edge portion to match the cross-sectional shape of the container body 2. The curl-forming portion 31 has an inner surface 32, an outer surface 34, and a curved bottom surface 35. The curling plate 30 has a first major surface 36 intended to face the tubular container body 2 when forming the curled edge 14. The inner surface 32 is provided with a plurality of protrusions 33 that protrude from the inner surface 32 into the curl-forming portion 31 and are spaced apart along the circumference of the curl-forming portion 31. The corners of the curl-forming portion 31 are free of protrusions 33. The distance between two adjacent protrusions 33 corresponds to at least the diameter φ of the protrusions 33. The diameter φ of each protrusion 33 is in the range of 2 mm to 20 mm, and more preferably in the range of 2 mm to 10 mm. The protrusions 33 protrude to a depth d of 1.5 mm or more from the inner surface 32 of the U-shaped track 31. The curl-forming portion 31 has approximately the same footprint as the first end 3 and the second end 5 of the tubular container body. In FIG. 1, the protrusions 33 are formed along the periphery of the curl-forming portion 31 by studs provided on the curl plate 30.

[0067] 1 shows the step after the first end opening 4 has been closed by the sealing disc 12. The tubular container body 2 and the curling tool 30 cooperate to introduce the first end 3 of the tubular container body 2 into the curl forming section 31.

[0068] Figure 2 shows the first end 3 of the tubular container body 2 being forced into the U-shaped track 31 of the curling tool 30. When the tubular container body 2 is forced into the curling tool 30, the first end 3 of the tubular container body 2 is forced toward the bottom surface 35 of the curl-forming portion 31 and then curves and bends to follow the curved bottom surface 35, as shown in Figure 3. When the first end 3 is forced further into the curling tool 30, the first end 3 is completely bent and folded inward, as shown in Figures 4 and 5, to form a first curled edge 14 having a curved edge portion 14a and an inner portion 14b. When the tubular container body 2 is pressed against the curved bottom surface 35 of the curl-forming section 31 and folded inward, the inner portion 14b of the curled edge 14 is pressed against the inner surface 32 and the spaced-apart projections 33, as shown in Figures 4 and 5. In Figures 4 and 5, the first end 3 of the tubular container body 2 is folded back and pressed against the peripheral flange 13 of the paperboard disk 12. Optionally, the paperboard disk 12 may be positioned at a greater distance from the first edge 10 so that the curled edge folds over on itself. The spaced-apart projections 33 move toward and away from the curl-forming section 31, further pressing the inner portion 14b against the bent edge 14. The projections 33 press against the paperboard material and deform the carton structural layers, reducing the stiffness of the paperboard material, resulting in a less bulky and more distinctive curled edge 14. Furthermore, the protrusions 33 break the paperboard material perpendicular to the curl direction, making it difficult for the paperboard material to return to its original shape, and allowing the curl to be set in a desired shape.

[0069] FIG. 6 shows the tubular container body 2 after the first curled edge portion 14 has been formed. The inner portion 14b of the first curled edge portion 14 has spaced indents 15 along the circumference of the tubular container body 2. The depth d (shown in FIG. 1) of the indents 15 is, for example, in the range of 0.2 mm to 6 mm. The corners 23, 24, and 25 at the first end 3 of the tubular container body 2 do not have indents 15 formed therein. Otherwise, if indents 15 were formed at these corners, the folding of material at the corners 23, 24, and 25 would be bulky and less smooth. The curled portion 31 has a depth d of 5 mm to 40 mm. t , for example, 10 mm to 30 mm depth d t It has the following characteristics.

[0070] In a subsequent step (not shown), the tubular container body is rotated so that the second end opening faces upward and the packaging container is filled with the bulk solid. Optionally, the packaging container may be sealed over the second end opening with a partially or completely removable shipping closure attached to the inside surface of the container body wall.

[0071] 7 shows an optional step for forming a packaging container with a second curled edge. Prior to this step, the second end opening 6 is closed at the second end of the tubular container body 2 by a paperboard disk 39 having a peripheral flange 40 bent toward the second end 5 of the paperboard packaging container 1. In this optional step, the second end 5 of the tubular container body 2 is directed upward and guided toward the first main surface 36 of the curling plate 30. As in the case of forming the first curled edge 14, the second end 5 is introduced into the curl-forming section 31 having spaced-apart protrusions 33 to form a second curled edge 38 having an indent 41, similar to the first curled edge 14.

[0072] Figure 8 shows a paperboard packaging container 1 for bulk solids according to the present invention, manufactured according to the method shown in Figures 1 to 7. The packaging container 1 comprises a tubular container body 2 made of a laminated sheet material having a carton base layer, a container bottom 16, and a container lid 17. The tubular container body 2 extends in the height direction H of the packaging container 1 from a first end 3 corresponding to the bottom end to a second end 5 corresponding to the upper end. In the packaging container according to the present invention, the first end corresponds to the upper or lower end of the packaging container.

[0073] The tubular container body 2 has a container body wall 7 having an inner surface 8 facing the inner compartment of the packaging container 1 and an outer surface 9 facing the opposite side of the inner compartment. The lid 17 of the packaging container is a snap-on lid. The lid 17 has a peripheral lid collar 27 having a lid abutment edge 28 configured to abut against a container body abutment edge 29, and a lid insert portion 37. An example of this type of lid is disclosed in WO 2017 / 180056. In such a packaging container, the container opening is closed by an upper paperboard disk 39. The upper paperboard disk 39 and the tubular container body 2 form part of the snap-on lid. Thus, the second end 5 of the tubular container body 2 forms the upper end of the package container 1, and the second curled edge 38 has an indent 41 in the inner portion 38b of the second curled edge 38, thereby forming a characteristic second bent edge 38a.

[0074] The packaging container may include any suitable type of lid. The lid need not be permanently connected to the container body, but may be removable. It should be noted that the closure mechanism shown in FIG. 2 is not limited to this, and the bottom end described herein may be used for packaging containers having other types of closure mechanisms for opening and closing the packaging container, for example, where the lid cooperates with a stiffening rim or a frame structure of the container body. The lid may be provided as part of the lid component. The lid component includes a rim to which the lid is connected via a hinge. The rim is attached to the container body and stabilizes the container opening. The lid component may include features such as a locking means for maintaining the lid in a closed position, a tamper-evident means, and a stacking means, as known in the art. The lid component is typically formed by injection molding of a thermoplastic material. [Explanation of symbols]

[0075] 1 package container 2. Tubular container body 3 First end 4 First end opening 5 Second end 6 Second end opening 7 Container body wall 8. Inner Surface 9 External surface 10 first edge portion 11 second edge portion 12 paperboard discs 13 Perimeter flange 14 Curled edge 14a Edge 14b Inner part 15 Indent 16 Bottom of container 17 Container lid 18 Front wall section 19 Back wall section 20 Side wall part 21 Side wall part 22 Corner 23 Corner 24 Corner 25 Corner 27 Outer lid color 28 Lid abutment edge 29 Container body abutment edge 30 curling tools 31 Curl forming part 32 Inner 33 Protrusion 34 Exterior 35 bottom 36 First principal surface 37 Lid insertion part 38 Second curled edge 38a Second bent edge 38b Inner part 39 Upper cardboard disc H Height direction

Claims

1. A method for forming a paperboard packaging container (1) from a rectangular body blank (2), comprising the steps of: The method comprises: a) providing the body blank having a first side edge and a second side edge; b) forming a tubular container body (2) from the body blank, the tubular container body (2) having a first end (3) with a first end opening (4), a second end (5) with a second end opening (6), and a container body wall (7) extending between the first end opening (4) and the second end opening (6) in the height direction (H) of the paperboard package container (1), the container body wall (7) having an inner surface (8) and an outer surface (9); c) sealing together the first and second side edges of the body blank; d) closing the first end opening (4) by forcing a paperboard disc (12) into the first end opening (4), the paperboard disc (12) having a peripheral flange (13) bent in the height direction (H) of the paperboard packaging container (1) towards the first end (3) of the tubular container body (2), the peripheral flange (13) of the paperboard disc (12) being tightly attached to the inner surface (8) of the container body wall (7); e) forcing the first end (3) of the tubular container body (2) into a curl-forming portion (31) of a curling tool (30), the curl-forming portion (31) having an inner tool surface (32) with three or more spaced apart protrusions (33), thereby curling the first end (3) of the container body wall (7) inward to form a first curled edge (14) having a curved edge portion (14a) and an inner portion (14b), and forming three or more protrusions (33) on the inner portion (14b) of the first curled edge (14). providing spaced indents (15) along the circumference of the tubular container body (2), the indents (15) being formed by spaced protrusions (33) on the tool inner surface (32), the spaced protrusions being spaced apart along the circumference of the curl-forming portion, wherein the protrusions (33) are pressed against the inner portion (14b) of the first curled edge (14), thereby deforming the inner portion (14b) of the first curled edge (14); f) filling the paperboard packaging container (1) with bulk solids; g) closing the second end opening (6); It is equipped with A method characterized in that after step c), step g) and the subsequent step f) are performed alternately.

2. the curl forming portion (31) is a U-shaped track having the same footprint as the first end (3) of the tubular container body so that the first end (3) of the tubular container body is fitted into the curl forming portion (31); 2. The method according to claim 1, wherein the tool inner surface (32) is the inner surface of the curl forming portion (31).

3. 3. The method according to claim 1, further comprising the step of: forcing the second end (5) of the tubular container body (2) into the curl-forming portion (31) of the curling tool (30) to curl the second end (5) of the container body wall (7) inward to form a second curled edge (38) having a curved edge portion (38a) and an inner portion (38b), and providing three or more spaced indents (41) in the inner portion (38b) of the first curled edge (38) along the circumference of the tubular container body (2), the indents (41) being formed by spaced protrusions (33) on the tool inner surface (32).

4. 2. The method according to claim 1, wherein the step of forcing the first end (3) of the tubular container body (2) into the curl-forming portion (31) of the curling tool (30) comprises forcing the first end of the tubular container body (2) toward the curled bottom surface of the curl-forming portion so that the first end of the tubular container body follows the curvature, then curves and folds together with the curved bottom surface (35), and so that the first end of the tubular container body is folded inward to form the first curled edge.

5. 5. The method according to claim 4, wherein the step of pushing the first end (3) of the tubular container body (2) into the curl-forming portion (31) of the curling tool (30) further comprises pushing the first end of the tubular container body toward the curled bottom surface of the curl-forming portion so that the inner portion of the first curled edge is pressed against the inner surface of the curl-forming portion and the spaced-apart protrusions.

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