Method of producing and filling a packaging container

Abstract

A method of producing and filling a paperboard packaging container with bulk solids material comprising forming a tubular container body, closing an upper body opening of the tubular container body, filling bulk solids into the container body a bottom body opening of the tubular containing body, closing the bottom body opening, and turning container body such that an upper end is directed upwards in a vertical direction, thereby allowing improved control of the pressure within the packaging container.

Claims

1. A method of producing and filling a paperboard packaging container with bulk solids comprising: a) forming a tubular container body from a paperboard sheet, said container body having an upper end with an upper body opening and a bottom end with a bottom body opening and a container body wall extending in a height direction (H) of said packaging container between said upper body opening and said bottom body opening, said container body wall having an inner surface and an outer surface, an upper end edge and an bottom end edge; b) attaching an inner partly or fully removable transport closure to said inner surface of said container body wall and/or sealing said upper body opening with a container lid; c) presenting said container body to a filling station with said bottom body opening of said container body directed upward in a vertical direction; d) filling bulk solids into said container body through said upwardly directed bottom body opening; e) presenting said container body to a bottom body opening sealing station comprising at least one guiding member forming an, as seen from the bottom end, upwardly extending guiding channel, f) closing said bottom body opening by pressing a bottom disc through said guiding channel and into said bottom body opening, wherein an internal gas pressure above ambient pressure is produced within said packaging container, wherein the bottom disc has a peripheral flange surrounding a bottom disc base portion, wherein said peripheral flange is flexed towards the lower end in said height direction (H), wherein said guiding channel extends away from said container body, in said height direction (H), with a length (L.sub.1), as measured from said bottom end edge, wherein said bottom disc is pressed into said bottom body opening with a length (L.sub.2) in said height direction, as measured between said bottom end edge and said bottom disc base portion, wherein the sum of L.sub.1 and L.sub.2 is at least 25 mm; g) attaching said flange to said inner surface of said container body wall by welding, wherein step g) is performed immediately after step f) while maintaining the internal gas pressure above the ambient pressure; and h) turning said container body, wherein said upper end is directed upwards in the vertical direction and said bottom end is directed downwards in the vertical direction, wherein the bottom disc is subjected to a combined influence of (A) the internal gas pressure and (B) bulk solids compressing against the bottom disc under gravity.

2. The method according to claim 1, wherein the sum of L.sub.1 and L.sub.2 is between 25 mm and 260 mm.

3. The method according to claim 2, wherein L.sub.2 is at least 5 mm.

4. The method according to claim 1, wherein L.sub.2 is at least 5 mm.

5. The method according to claim 1, wherein L.sub.1 is at least 20 mm.

6. The method according to claim 1, wherein said guiding member encloses 80% or more of a perimeter of said container body.

7. The method according to claim 6, wherein said guiding member encloses 95% or more of the perimeter of said container body.

8. The method according to claim 1, wherein said guiding member is in the form of a closed guiding channel, enclosing a perimeter of said container body entirely.

9. The method according to claim 1, wherein a size ratio of a surface area of the bottom disc to a surface area of the bottom body opening is at least 1.01, wherein an outer edge portion of said bottom disc is shaped and flexed when said bottom disc is pressed into said body bottom opening, wherein said outer edge portion of said bottom disc forms a flange projecting out of a main plane of said bottom disc, wherein said flange is aligned with said inner surface of said container body wall.

10. The method according to claim 9, wherein said size ratio of said bottom disc surface area to said bottom body opening surface area is from 1.01 to 1.3.

11. The method according to claim 1, wherein said bottom disc is pressed into said bottom body opening with a speed from 30 mm/s to 150 mm/s.

12. The method according to claim 1, wherein said bottom disc comprises reinforcing elements.

13. The method according to claim 12, wherein said reinforcing elements comprises embossed continuous or discontinuous lines.

14. The method according to claim 1, wherein said bulk solids is a pulverulent material.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The present invention will be further explained hereinafter by means of non-limiting examples and with reference to the appended drawings wherein:

(2) FIG. 1 illustrates a packaging container according to the present disclosure;

(3) FIG. 2 shows an exploded view of the packaging container according to the present disclosure;

(4) FIG. 3 shows schematically a process for producing and filling the packaging container in FIG. 1; and

(5) FIG. 4 shows a cross-section taken along the line IV-IV in FIG. 3.

DETAILED DESCRIPTION

(6) It is to be understood that the drawings are schematic and that individual components, such as layers of materials are not necessarily drawn to scale. The packaging containers shown in the figures are provided as examples only and should not be considered limiting to the invention. Accordingly, the scope of invention is determined solely by the scope of the appended claims.

(7) FIGS. 1 and 2 illustrate a paperboard packaging container 1 for bulk solids according to the present disclosure. The particular shape of the container 1 shown in the figures should not be considered limiting to the invention. Accordingly, a packaging container produced according to the invention may have any useful shape or size.

(8) The packaging container 1 comprises a container body 2 having a container body wall 3 extending in a height direction of the container between an upper end 4 with an upper body opening 6′ and a bottom end 5 with a bottom body opening 6″. The container body wall 3 has an inner surface 7 facing towards an inner compartment 22 in the packaging container 1 and an outer surface 8 facing away from the inner compartment 22. The container body 2 is made from paperboard material as defined herein.

(9) The packaging container 1 furthermore comprises an inner partly or fully removable transport closure 14 forming a cross-sectional seal between the inner compartment 22 in the container body 2 and the upper body opening 6′, as shown in FIG. 2. The packaging container 1 also comprises a closure arrangement comprising a container lid 19 and a bottom disc 9 sealing the bottom body opening 6″. As shown in FIG. 2, the bottom disc 9 comprises a bottom disc outer edge portion 10 surrounding a bottom disc base portion 11. The outer edge portion 10 may be flexed and shaped during insertion and projects out of a main plane of the bottom disc 9 to form a flange 10′ aligned with the inner surface 7 of said container wall 3. However, the bottom disc 9 may also, as shown in FIG. 3, be pre-formed, such that the outer edge portion 10 already is flexed and shaped to a peripheral flange 10′ projecting out of a main plain of the bottom disc before being pressed into the bottom body opening 6″ at the bottom end 5. The bottom disc 9 comprises reinforcing elements 26 in the form of continuous embossed lines.

(10) The flange 10′ is subsequently sealed against the inner surface 7. The bottom disc 9 is attached by welding, such as by high frequency welding, to the inner surface 7 of the container body wall 3 to ensure a tight seal between the flange 10′ and the inner surface 7. While the bottom disc may be made from any suitable material such as paperboard, plastic or metal, paperboard bottom discs may generally be preferred.

(11) As shown in FIG. 2, the packaging container 1 may furthermore be provided with a bottom reinforcement rim 16. The bottom reinforcement rim 16 may be joined to the inner surface 7 of the container body wall 3 by welding such that a more reliably sift-proof joint between the rim 16 and the container wall 3 can be achieved, than with an adhesive seal.

(12) The packaging container may furthermore, for reinforcement, be provided with an upper reinforcing rim 17 to the upper body opening 6′ and a frame structure 18, which may be mechanically connected with the upper reinforcing rim 17. The frame structure 18 may then serve to provide features such as a lid hinge. The frame structure 18 is in FIGS. 1 and 2 provided with locking elements 20 for retaining the lid 19 in a closed position over the access opening.

(13) The application of a bottom reinforcing rim 16 to the bottom end of the packaging container, an upper reinforcing rim 17 to the upper body opening 6′ and a frame structure 18 is optional for the packaging container disclosed herein.

(14) A packaging container as shown in FIGS. 1 and 2 may be produced and filled by the method illustrated in FIG. 3. The method involves forming a tubular container body 2 from a paperboard sheet 2′ by bringing together the side edges 23,24 of the paperboard sheet 2′, thus causing the material to assume a tubular shape. The side edges 23,24 of the paperboard sheet 2′ are then sealed together. Sealing of the side edges may be made by any suitable method as known in the art, such as by welding or gluing, with welding being preferred. In the process shown in FIG. 3, the side edges 23,24 of the container body sheet 2′ are sealed using a sealing strip 26. The use of a sealing strip 26 is optional to the invention.

(15) The container body 2 has an upper end 4 with an upper body opening 6′ and a bottom end 5 with a bottom body opening 6″ and a container wall 3 extending between the upper end 4 and the bottom end 5. The container wall has an inner surface 7, an outer surface 8, an upper end edge 12 and a bottom end edge 13.

(16) The upper body opening 6′ is closed by applying a transport closure 14 across the opening 6′ and attaching a peripheral edge portion of the transport closure 14 to the inner surface 7 of the container wall 3 at a distance from the upper end edge 12 of the container wall 3. The transport closure 14 is preferably attached by being welded to the inner surface 7 of the container wall 3. The weld seal may be a peelable seal or a permanent seal. If the weld seal is a permanent seal, the transport closure 14 is preferably provided with means to allow it to be torn open by a user. Such tearing means may be perforations or other tear indications as disclosed herein.

(17) An upper reinforcing rim 17 in the form of a closed loop with a main extension in a loop plane may subsequently be provided. The upper reinforcing rim 17 has an upper rim part and a bottom rim part in the height direction of the upper reinforcing rim 17 and is applied to the container body by inserting the lower rim part into the upper body opening 6′ of the container body 2. However, also the upper part of the upper reinforcing rim 17 may be inserted into the container body 2.

(18) Accordingly, the upper reinforcing rim 17 may be inserted into the container body 2 such that an upper end edge of the upper reinforcing rim 17 remains outside of the container body 2 or is flush with the upper end edge 12 of the container wall 3.

(19) By inserting the upper reinforcing rim 17 which is more rigid than the container body 2 into the container body, the upper end edge 12 of the container body 2 is brought to conform to the outer contour of the upper reinforcing rim 17. Accordingly, the application of the upper reinforcing rim 17 to the container body wall 3 serves to bring the upper end edge 12 and thereby also the container wall 3 to assume a cross-sectional shape following the contour of the upper reinforcing rim 17. Additionally, as the packaging container 1 is turned and filled upside-down the upper reinforcement rim 17 provide support for the upper end edge 12 during filling of the inner compartment 22.

(20) A weld seal may thereafter be formed between the inner surface 7 of the container body wall 3 and the inserted lower part of the upper reinforcing rim 17. As described herein, the weld seal is preferably a high frequency weld seal and is formed by applying heat and pressure perpendicular to the container body wall 3 to melt and locally soften thermoplastic components in the upper reinforcing rim 17 and/or on the inner surface 7 of the container body wall 3.

(21) The partly assembled packaging container is then turned upside-down as indicated by the arrow A until the bottom body opening 6″ and the bottom end 5 of the container body 2 comes to be directed upward and is introduced into a filling station where bulk solids is filled into the container body 2 through the upwardly directed bottom body opening 6″.

(22) It should be understood that the upper reinforcing rim 17 may alternatively be attached while the packaging container 1 is in the upside-down position shown after the arrow A. In such case, the packaging container 1 already has the correct orientation when presented to the filling station and no turning step is carried out. It is to be understood, that the container body 2 may be held in any suitable position during process steps a) of forming a tubular container body 2 and, b) attaching an inner transport closure 14, as long as it is presented to the filling station with the bottom opening directed upwardly as shown after the arrow A in FIG. 3. It should furthermore be understood that the upper reinforcing rim 17 is optional for the packaging container 1, and the packaging container 1 may also not comprise an upper reinforcement rim at all.

(23) Subsequently, the bottom body opening 6″ is closed at a bottom body opening sealing station comprising a closed guiding channel 15′ formed by a guiding member 15 enclosing the circumference of the container body and forming an channel extending in an upwards direction from the bottom end edge 13. The bottom body opening 6″ is closed by pressing the bottom disc 9 through the guiding channel 15′ and into the bottom body opening 6″ by means of a pressing foot 21. By pressing the bottom disc 9 through the guiding channel 15′ a pre-set and thus controlled pressure above the ambient pressure is produced within the inner compartment 22 of the packaging container 1. The surface area of the bottom disc 9 has a size ratio of at least 1.01 to the surface area of the body bottom opening 6″. The bottom disc may either be shaped before insertion into the bottom body opening 6″ by bending the outer edge portion(s) 10 of the bottom disc 9 to create a flange 10′ that can be welded to the inner surface 7 of the container body wall 3, or alternatively the outer edge portion(s) 10 is shaped and flexed when the bottom disc 9 is pressed into the guiding channel 15′, such that the outer edge portion(s) forms a flange 10′ projecting out of a main plane of the bottom disc 9 that can be welded to the inner surface 7 of the container body wall 3.

(24) The guiding channel 15′ extends away from said container body 2, in the height direction (H), with a length (L.sub.1), as measured from said bottom end edge (13). The bottom disc (9) is pressed into the bottom body opening 6″ with a length L.sub.2 in the height direction, as measured between the bottom end edge 13 and the bottom disc base portion 11, at the peripheral edge of the base portion 11. The sum of L.sub.1 and L.sub.2 is at least 25 mm.

(25) The bottom disc 9 is pressed by means of the pressing foot 21 with a speed of at least 30 mm/s and not more than 150 mm/s.

(26) The guiding channel 15′ is a combined welding means 27 and guiding channel 15′ comprising a first welding means for performing the step of attaching the bottom disc 9 to the inner surface 7 of the container body 2 by welding.

(27) While the bottom disc may be made from any suitable material such as paperboard, plastic or metal, paperboard bottom discs may generally be preferred. The bottom disc preferably comprises a material having a stiffness of from 100 mN to 1500 mN. When the bottom disc comprises relatively stiff material, the bottom disc preferably comprises folding lines corresponding to the size and shape of the body bottom opening to enable prefolding of the outer edge portions 10 or folding of the outer edge portions 10 when the bottom disc 9 is pressed into the bottom body opening 6″. The bottom disc 9 is attached by welding, such as by high frequency welding, to the inner surface 7 of the container body wall 3 immediately after the step of closing the body bottom opening 6″ with the bottom disc 9.

(28) After the bottom disc 9 has been applied over the bottom body opening 6″, a bottom reinforcing rim 16 may be attached to the inner wall 7 of the container body 2 at the bottom end 13 of the container body 2.

(29) The application of a bottom reinforcing rim 16 to the bottom end of the packaging container is optional to the process as disclosed herein.

(30) The partly assembled packaging container is then turned again as indicated by the arrow B until the upper end 4 of the container body 2 comes to be directed upward whereafter a lid component including a container lid 19 and a frame structure 18 is snapped onto the upper reinforcing rim 17 to produce the fully assembled and filled packaging container 1.

(31) It is to be understood that the upper body opening 6′ may alternatively be closed with the transport closure 14 after the upper reinforcing rim 17 has been applied to the container body 2. A further alternative is to apply the transport closure 14 from the bottom end 13 of the container body 2 which is preferably done after the container body has been turned upside-down as indicated by the arrow B in FIG. 3. Accordingly, the transport closure 14 can be applied at any suitable point in the process, as long as it is applied before the filling step, as the sealing membrane 14 is needed to keep the bulk solids in the container body 2 during the filling step.

(32) It is also to be understood that it is optional to the process as disclosed herein to apply a frame structure/lid component to the upper reinforcing rim 17. Accordingly, the filled and bottom-sealed packaging container may alternatively be provided with a lid which is directly applied to the upper reinforcing rim 17, either as a completely removable lid or as a lid which is attached to the upper reinforcing rim 15 by means of a two-part hinge. The container lid may also be an integrated lid comprising a plug-in portion, as disclosed in EP 0 611 703 B1.

(33) It is an advantage of a lid construction as shown in the figures that a frame structure 18 or a whole lid component can be attached to the upper reinforcing rim 17 after the container 1 has been filled and closed around the contents 25. In this manner, the risk that the lid component or frame structure 18 is damaged in the production and filling process is minimized. Furthermore, by attaching a three-dimensionally shaped lid component or frame structure 18 at a late stage in the process, the packaging container 1 can be filled from the bottom end of the container body 2, which means that the transport closure 14 can be applied in the packaging container before the container is filled. An advantage with applying the transport closure 14 in the packaging container before the packaging container is filled with bulk solids 25 is that there is no risk that the seal between the membrane and the container wall is contaminated by the bulk solids.

(34) Furthermore, there is no risk that any of the packaged bulk solids will end up outside the transport closure 14, in the space between the lid and the transport closure, which may happen if the transport closure is applied after filling of the packaging container. A user opening a new packaging container for a first time and finding some of the contents outside the sealing membrane would consider the container to be less hygienic and reliable than a container in which the space between the transport closure and the lid is completely clean.

(35) With reference to FIG. 4, there is shown a cross section of the bottom body opening sealing station taken along the line IV-IV in FIG. 3. FIG. 4 illustrates the bottom body opening sealing station wherein the pressing foot has pressed the bottom disc 9 through the guiding channel 15′ and into the bottom body opening 6″ such that a slight pressure above the ambient pressure is produced. The guiding channel 15′ extends with a length L1 of 8 cm in a height direction from the bottom end edge 13 of the container body 2. The guiding channel 15′ is provided with a welding means 27 for providing a welding seam.