SE542047C2

SE542047C2 - Sealing disc for packaging container with controlled internal pressure and methods for producing and filling such container

Info

Publication number: SE542047C2
Application number: SE1650995A
Authority: SE
Inventors: Henrik Herlin; Lennart Larsson; Maria Siöland; Simon Holka
Original assignee: A & R Carton Lund Ab
Priority date: 2016-07-06
Filing date: 2016-07-06
Publication date: 2020-02-18
Also published as: SE1650995A1; EP3481733A1; CN109476397B; ES2870076T3; EP3481733A4; EP3481733B1; WO2018009130A1; PL3481733T3; CN109476397A

Abstract

The present disclosure relates to a paperboard sealing disc (10) for use in a paperboard packaging container (1) for bulk solids. The packaging container (1) comprises a container body (2) with an upper end (4) with an upper body opening (5’) and a bottom end (6) with a bottom body opening (5”), a container wall (3) extending between the upper end (4) and the bottom end (6) in a longitudinal direction (L). The container wall (3) has an inner surface (7) facing towards an inner compartment (9) in the packaging container (1) and an outer surface (8) facing away from the inner compartment (9). The sealing disc (10) is intended for sealing the upper body opening (5’) or the bottom body opening (5"). The sealing disc (10) comprises a sealing disc border (11) surrounding a sealing disc base portion (12), wherein the border (11) is delimited from the disc base portion (12) by a sealing disc inner folding edge (31). The sealing disc border (11) is intended to be flexed at the inner folding edge (31) to project out of a main plane of the sealing disc (10) and to be aligned with and sealed to the inner surface (7) of the container wall (3). The sealing disc (10) comprises one or more distance element(s) (14) arranged in the sealing disc border (11), the distance element(s) (14) having a height (H), as measured from the surface of the sealing disc border (11). Methods for producing and filling a paperboard packaging container (1) with bulk solids (25) are also disclosed.

Description

SEALING DISC FOR PACKAGING CONTAINER WITH CONTROLLED INTERNAL PRESSURE AND METHODS FOR PRODUCING AND FILLING SUCH CONTAINER TECHNICAL FIELD The present disclosure pertains to a paperboard sealing disc for use in a paperboard packaging container for bulk solids. The present disclosure also relates to methods for producing a paperboard packaging container comprising the paperboard sealing disc.

BACKGROUND When packaging consumer goods, and in particular when packaging bulk solids, such as dry flowable consumer goods, it is common to use rigid paperboard packaging containers which serve as protective transport and storage containers at the retail end and as storage and dispensing containers at the consumer end. Such paperboard containers are usually provided with an openable and closable lid, and with an inner removable or breakable transport closure which keeps the contents fresh and protected against contamination up until the container is opened by a consumer.

The bulk solids may be filled into a paperboard packaging container either from the container top or from the container bottom. In packaging systems where the paperboard packaging container is sealed by a sealing disc, such as an upper transport sealing member or a bottom sealing disc when the packaging containers are filled from the bottom, it has been found that a pressure above the ambient pressure may be built up within the packaging container when the sealing disc is pressed into the opening, upper opening or bottom opening, during sealing of the packaging container subsequent to the filling step. For such packaging systems it has been found that there exists a need to improve control of the pressure within the packaging container.

SUMMARY One object of the present disclosure is to provide a paperboard sealing disc for use in a paperboard packaging container which enables a controlled and stabilized pressure within the packaging container during sealing of the paperboard packaging container.

This and other objects of the present disclosure may be achieved by a paperboard sealing disc for use in a paperboard packaging container according to claim 1. Further embodiments are set out in the dependent claims, in the following description and in the drawings.

As such, the present disclosure relates to a paperboard sealing for use in a paperboard packaging container for bulk solids. The packaging container comprises a container body with an upper end with an upper body opening and a bottom end with a bottom body opening, a container wall extending between the upper end and the bottom end in a height direction H. The container wall has an inner surface facing towards an inner compartment in the packaging container and an outer surface facing away from the inner compartment. The sealing disc is intended for sealing the upper body opening or the bottom body opening. The sealing disc comprises a sealing disc border surrounding a sealing disc base portion, wherein the border is delimited from the disc base portion by a sealing disc inner folding edge. The sealing disc border is intended to be flexed at the inner folding edge and to project out of a main plane of the sealing disc and to be aligned with and sealed to the inner surface of the container wall. The sealing disc comprises one or more distance element(s) arranged in the sealing disc border, the distance element(s) having a height h, as measured from the surface of the sealing disc border.

The purpose of the distance elements is to form air conveying passages between the sealing disc border and the inner wall of the packaging to allowing air/gas to pass out between the sealing disc and the container wall in a controlled manner when applying the sealing disc in either the upper body opening or the bottom body opening, depending on in which end the packaging container is finally sealed. The provision of air conveying passages between the sealing disc and the inner wall of the packaging container makes it possible to control the pressure level within the inner compartment of the packaging container during and after production of the packaging container.

As may be understood by the skilled person, an alternative to provide the sealing disc with distance elements and air passages is to include air passages in the packaging container inner wall.

The paperboard sealing disc is suitably applied after the paperboard packaging container has been filled from the upper body opening, after the bottom body opening has been closed, or alternatively after the paperboard packaging container has been filled from the packaging bottom, after the upper body opening has been initially closed, and in which a pressure above ambient pressure may be produced within the inner compartment of the packaging container, such as when the sealing disc is pressed into either the upper body opening or the bottom body opening for final sealing of the packaging container inner compartment.

The fact that the sealing disc provides air conveying passages during the assembly steps allows for a controlled and predetermined amount of air or gas passing out from the inner compartment of the packaging container when sealing the container inner compartment after filling. The air conveying passages are provided between the border forming a flange and the inner surface of the container wall and are formed by the one or more distance element(s) to provide for controlled air outlet when the inner pressure rapidly rises above the ambient pressure during production of the packaging container. After attachment of the borders to the inner surface of the container wall, the distance elements are compressed, but will remain identifiable as compression marks at the outer surface of the sealing disc border. As the distance elements are provided prior to closing the bottom body opening, the container wall does not comprise any compression marks.

A controlled and stabilized pressure within the inner compartment in a closed packaging container has been found to be advantageous as it contributes to ensuring a uniform pressure level within the inner compartment between different packaging containers produced in the same production line. The fact that the inner compartments of all packaging containers produced in the same run have a uniform inner pressure gives the advantage of uniformly shaped packages which are easier to arrange in uniform and stable stacks and to provide with a secondary package.

The bulk solids may be a pulverulent material.

The sealing disc is defined by outer edges, the distance elements may extend all the way to the outer edges or may be arranged at a distance from the outer edges.

Optionally, the sealing disc comprises two or more distance elements arranged side-byside in the sealing disc border and defining at least an air conveying passages between the distance elements. The air conveying passage(s) is present before attachment of the flange to the inner surface of the container wall when the distance elements are compressed and the distance between the compressed distance elements corresponds to the width of the air conveying passages. Optionally the sealing disc comprises at least 4 or 6 or 10 distance elements, such as between from 3 and 80 distance elements, such as between from 20 to 100 distance elements.

The distance elements may be equidistantly distributed along the sealing disc border.

Optionally, the distance elements are provided at the sealing disc inner folding edge and/or with a distance of not more than 1 mm from the sealing disc inner folding edge. Optionally, the distance elements are provided with a distance within the range of from 0 to 0.1 mm from the sealing disc inner folding edge.

The fact that the distance elements are provided at the sealing disc inner folding edge and/or with a distance of not more than 1 mm from the sealing disc inner folding edge, such that the distance element(s) are provided on or close to the inner folding edge, contributes to that the air conveying passages remain open towards the inner compartment of the packaging container during insertion of the sealing disc into the bottom body opening, thus allowing a free passage of air or gas out from the inner compartment when the inner pressure rapidly raises above the ambient pressure during production of the packaging container.

The sealing disc inner folding edge is thus arranged along the line where the sealing disc border is intended to be flexed when introduced into the paperboard packaging container, such that the sealing disc border may be attached to the inner wall of the container wall. The sealing disc inner folding edge may be an imaginary inner folding edge prior to insertion of the sealing disc into the packaging container or may also constitute of a preformed folding line or crease line facilitating folding along the inner folding edge before folding the sealing disc such that the sealing disc border is flexed and shaped to a peripheral flange.

Optionally, the distance elements are elongated distance elements having a length of at least 1 mm, such as from 1 to 15 mm, and form air conveying passage(s) in the form of air conveying channel(s) having a length of at least 1 mm, such as from 1 to 15 mm.

The distance element(s) may be elongated distance element(s) extending from, or over, the sealing disc inner folding edge to the sealing disc outer edges.

The fact that the distance elements have a length of at least 1 mm and thus form one or more air conveying channels of at least 1 mm gives an effective passage-way between the inner compartment and the outside of the packaging container during production of the packaging container, allowing air or other gaseous media to flow out from the inner compartment of the packaging container when the pressure within the inner compartment raises above the ambient pressure.

Optionally, the elongated distance elements extend across the sealing disc inner folding edge and on to the sealing disc base portion.

Optionally, the height of the distance elements is 0.005 mm or more, such as from 0.005 mm to 3 mm, or such as from 0.003 mm to 1 mm, the height H being measured from the inner surface of the sealing disc, i.e. the surface intended to face the inner surface of the container wall.

The height h of the distance elements being at least 0.005 mm, such as within the range of from 0.005 mm to 3 mm, implies a corresponding depth of at least 0.005 mm, such as between 0.03 mm to 1 mm of the one or more air conveying passage(s) defined between the distance elements during insertion of the sealing disc and ensures an effective open passage for air or other gaseous media out from the inner compartment of the packaging container when the pressure within the inner compartment exceeds the ambient pressure during production of the packaging container as disclosed herein.

Optionally, the sealing disc has a longitudinal direction y and a transverse direction x perpendicular to the longitudinal direction with a length of the sealing disc as measured in the longitudinal direction being greater than a width of the sealing disc in the transverse direction, and first and second longitudinal opposing border having a main extension in the longitudinal direction. The sealing disc may further have first and second transverse opposing side portions having a main extension in the transverse direction. The first and second longitudinal opposing side portions and the first and second transverse opposing side portions extend between corner portions, which are preferably curved corner portions, such as corner portions having a radius of curvature within the range of from 5 to 60 mm, preferably within the range of from 10 to 40 mm, more preferably within the range of from 15 to 30 mm. The sealing disc may preferably have a modified rectangular shape with rounded comer portions. A modified rectangular shape as used herein, includes shapes with rounded corner portions and linear longitudinal and transverse side portions as well as those shapes wherein one or more of the longitudinal and transverse side portions of the sealing disc is slightly curved, e.g. with a radius of curvature within the range of from 200 to 700 mm, preferably within the range of from 300 to 600 mm, more preferably within the range of from 400 to 500 mm.

The distance elements may extend side-by-side between the first and second longitudinal opposing border in the transverse direction of the sealing disc or with at least a main extension in the transverse direction of the sealing disc, i.e. the distance elements may extend at a small angle to the transverse direction, such as at a deviation from the transverse direction of the sealing disc of at most 20°.

The distance elements may extend parallel to each other or with an angle between them. The distance elements may also intersect with each other at the sealing disc base portion. For reasons of stability and improved deformation resistance of the sealing disc, it may be preferred to arrange distance elements extending parallel to each other in the transverse direction of the sealing disc As set out herein, the corner portions may be curved portions and may be free of distance elements.

Corner portions which are free from distance elements improve the seal between the flange and the inner surface, as it reduces the risk of wrinkles being formed adjacent to the distance elements in the border when folding the border to form a flange. Wrinkles in the folded flange portion of the sealing disc may otherwise impair the seal between the flange of the sealing disc and the inner surface.

Optionally, at least two distance elements extend across the sealing disc forming at least one air conveying channel extending between two opposing disc side portions and over the sealing disc base portion. The border may be the first and second longitudinal opposing side portions and/or the first and second transverse opposing side portions.

Distance elements extending across the sealing disc and over the sealing disc base portion may provide increased stability to the sealing disc during application of the sealing disc into the sealing end as there will be a certain pressure against the sealing disc provided by the compressed air which may cause deflection of the sealing disc.

By “sealing disc base portion” is meant a portion of the sealing disc surrounded by a peripheral sealing disc portion comprising the borders of the sealing disc forming the peripheral flange.

The flange of the sealing disc is either preformed or formed when closing the upper or bottom body opening by pressing a sealing disc into the upper or bottom body opening. A typical size ratio of the sealing disc surface area to the relevant upper or bottom body opening surface area may be 1.05 or more, such as from 1.0 to 1.2. The border of the sealing disc may be deformed and flexed when the sealing disc is pressed into the body upper/bottom opening, such that the border of the sealing disc forms a flange projecting out of a main plane of the sealing disc, the flange is then aligned with the inner surface of the container body wall.

Optionally, the distance elements comprise or consist of embossed dots or lines in the sealing disc. An embossed distance element in the form of a dot may have a diameter within the range of from 1 to 4 mm and an embossed distance element in the form of a line may have a width or diameter within the range of from 1 to 4 mm. The embossed elements in the sealing disc may be in the form of straight or curved lines, with dots or straight lines generally being preferred.

Optionally, the distance elements comprise or consist of reinforcing strips.

Optionally, the sealing disc comprises at least four air conveying passages, Optionally, the sealing disc comprises reinforcing elements in addition to the elongated ridge elements, such as reinforcing elements provided in, and extending only within, the sealing disc base portion. Such additional reinforcing elements need not be arranged to provide gas passages and can take on any suitable shape such as circles, H-shapes, X-shapes, as well as logos, text, graphics, etc.

The reinforcing elements provide the sealing disc with enhanced rigidity, which may be advantageous during insertion of the sealing disc into the upper/bottom end opening as there will be a certain pressure exerted on the sealing disc by the rapidly compressed air in the inner compartment. The elevated pressure inside the packaging container may cause deflection of the sealing disc. By the provision of reinforcing elements in the sealing disc, deflection of the sealing disc may be reduced whereby the reinforcing elements contribute to creating a controlled and predetermined pressure within the inner compartment of the packaging container.

Optionally, the sealing disc is a bottom disc.

When the sealing disc is a bottom disc, the packaging container is first closed at the upper body opening with an inner partly or fully removable transport closure forming a crosssectional seal between the inner compartment in the container body and the upper body opening. The packaging container is subsequently filled from the bottom body opening with the bulk solids and finally the packaging container is sealed with the sealing disc according to the present disclosing, the sealing disc thus being a bottom disc.

Optionally, the sealing disc is an inner partly or fully removable transport closure which may form a cross-sectional seal between the inner compartment in the container body and the upper body opening.

When the sealing disc is an inner partly or fully removable transport closure, the packaging container is first closed at the bottom body opening by means of a bottom disc or folded bottom portions, as known in the art. The packaging container is subsequently filled with the bulk solids from the upper body opening and finally the packaging container is sealed with the sealing disc as disclosed herein, the sealing disc thus being an inner partly or fully removable transport closure.

The shape of the sealing disc corresponds to the shape of the container body at the container upper body opening when the sealing disc is an inner partly or fully removable transport disc or to the bottom body opening when the sealing disc is a bottom disc. The shape of the packaging container at the bottom of the packaging container may be further stabilized by means of a reinforcing bottom rim, such as a plastic bottom rim.

In a second aspect, the present disclosure relates to a method of producing and filling a paperboard packaging container with bulk solids according to the first aspect wherein the sealing disc is a bottom disc, wherein the method comprises the steps of: a) forming a tubular container body from a paperboard sheet, the 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 the packaging container between the upper body opening and the bottom body opening, the 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 the inner surface of the container body wall and/or closing the upper body opening with a container lid (16) and; c) presenting the container body to a filling station with the bottom body opening of the container body directed upward in a vertical direction; d) filling bulk solids into the container body through the upwardly directed bottom body opening; e) closing the bottom body opening by pressing a sealing disc into the bottom body opening, the sealing disc comprising a sealing disc border surrounding a sealing disc base portion, the sealing disc border being formed into a flange by being flexed towards the upper end in the height direction H, the sealing disc comprising one or more distance element(s) being arranged in the sealing disc border on an inner surface facing the container body wall, the distance elements having a height h in a direction perpendicular to the height direction H of the container wall, with two or more air conveying passages being defined on each side of the one or more distance element(s) and between the inner surface of the sealing disc border and the container wall, and; f) attaching the flange to the inner surface of the container body wall.

In a third aspect, the present disclosure relates method of producing and filling a paperboard packaging container with bulk solids according to the first aspect wherein the sealing disc is a an inner partly or fully removable transport closure, characterized in that the method comprises the steps of: a) forming a tubular container body from a paperboard sheet, the 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 of the packaging container between the upper body opening and the bottom body opening, the container body wall having an inner surface and an outer surface, an upper end edge and an bottom end edge; b) closing the bottom body opening; c) presenting the container body to a filling station with the upper body opening of the container body directed upward in a vertical direction; d) filling bulk solids into the container body through the upwardly directed upper body opening; e) closing the upper body opening by pressing a sealing disc into the upper body opening, the sealing disc comprising a sealing disc border surrounding a sealing disc base portion, the sealing disc border being formed into a flange by being flexed towards the upper end in the height direction, the sealing disc comprising one or more distance element(s) being arranged in the sealing disc border on an inner surface facing the container body wall, the distance elements having a height h in a direction perpendicular to the height direction H of the container wall, with two or more air conveying passages being defined on each side of the one or more distance element(s) and between the inner surface of the sealing disc border and the container wall, and; f) attaching the flange to the inner surface of the container body wall.

Optionally, the sealing disc comprises two or more distance elements arranged side-byside in the sealing disc border and defining one or more air conveying passages between the distance elements, and wherein the air conveying passage(s) defined between the distance elements has/have a width of from 1 to 20 mm.

Optionally, the height of the distance elements is at least 0.005 mm, such as from 0.005 mm to 3 mm, as measured from the inner surface of the sealing disc border. Optionally, the height of the distance elements is at least 0.03 mm, such as from 0.03 mm to 1 mm.

Optionally, the sealing disc is pre-formed and already flexed and shaped to a flange before being pressed into the body upper/bottom opening.

Optionally, and according to the second or the third aspect, the flange of the sealing disc is attached to the inner surface of the container wall by means of a welded gas tight seal in step g) or f) respectively.

The welding process provides a highly controlled way of creating a seal with a predetermined tightness between the sealing disc and the paperboard container wall. The seal is made by supplying energy to heat and locally soften or melt one or more thermoplastic component on the inner surface of the container wall and on the sealing disc and by pressing the sealing disc and the container wall together in a direction perpendicular to the container wall. The thermoplastic material used to create the weld seal may be provided by a thermoplastic film or coating on the inner surface of the container wall and/or on the sealing disc.

As used herein, a paperboard packaging container is a packaging container wherein the container body is formed from paperboard web material. The paperboard container may be formed in any manner known in the art, e.g. by forming a container body by bending the paperboard web material into a tubular shape and longitudinally closing the tube by joining overlapping or abutting side edges of the sheet material. The join between the side edges may be covered by a sealing strip.

As used herein, a paperboard web material is a material predominantly made from cellulose fibers or paper fibers. The web material may be provided in the form of a continuous web or may be provided as individual sheets of material. The paperboard material may be a single ply or multi ply material and may be a laminate comprising one or more layers of materials such as polymeric films and coatings, metal foil, etc. The polymeric films and coatings may include or consist of thermoplastic polymers. The paperboard materials as disclosed herein may also be referred to as cardboard or carton materials.

As used herein, the term “bulk solids" refers to a solid material. The bulk material may be dry or moist. The bulk solids may be in the form of particles, granules, grinds, plant fragments, short fibres, flakes, seeds, formed pieces of material such as pasta, etc.

The bulk solids which are suitable for packaging in the packaging containers as disclosed herein may be flowable, which means that a desired amount of the product may be poured or scooped out of the packaging container, or in the form of discreet pieces of material allowing removal of only part of the content in the packaging container.

By a “pulverulent material” as used herein is implied any material in the form of particles, granules, grinds, plant fragments, short fibres, flakes, etc.

A partly or fully removable transport closure may be gastight or gas-permeable. A gastight member may be manufactured from any material or material combination suitable for providing a gastight sealing of a compartment delimited by the transport closure, such as aluminium foil, silicon-coated paper, plastic film, or laminates thereof. A gastight member is advantageous when the bulk solids stored in the packaging container are sensitive to air and/or moisture, and it is desirable to avoid contact of the packaged bulk solids with ambient air. According to the present disclosure a gastight transport closure is preferred as the purpose is to produce and maintained a controlled and stabilized pressure within the packaging container.

In the assembled and filled packaging container which is disclosed herein, the peelable or openable transport closure forms a cross-sectional seal between an inner compartment in the container body and the container opening. The inner peelable or openable transport closure is a transport and storage seal which is eventually broken or removed by an end user of the packaging container.

A packaging container having a volume of approximately 11 may be considered to be gastight if it provides an oxygen barrier of approximately 0.006 cc oxygen/24 h or less at 23 °C and 50% relative humidity.

Optionally, the packaging container comprises a closure arrangement comprising a lid for closing the upper body opening. The lid may be arranged to cooperate with an upper rim which is attached at the upper container body opening. The upper rim may be a single plastic rim or a two-part rim construction arranged to reinforce and stabilize the upper container body opening on a paperboard packaging container. The upper rim or a part of a two-part rim construction may be hingedly connected to the lid.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention will be further explained hereinafter by means of non-limiting examples and with reference to the appended drawings wherein: Fig. 1 illustrates a packaging container according to the present disclosure; Fig. 2 shows an exploded view of a packaging container according to the present disclosure; Fig. 3 illustrates a perspective view of a bottom disc according to the present disclosure; Fig. 4 illustrates a perspective view of the bottom disc according to Fig. 3 with the disc border flexed to form a flange; Fig. 5 illustrates a cross-section taken along the line V-V in Fig 4; Fig. 6 illustrates a perspective view of the bottom disc according to Fig. 4; Fig. 7 illustrates a perspective view of a bottom disc according to the present disclosure; Fig. 8 illustrates a cross-section taken along the line VIII-VIII in Fig. 7; Fig. 9 illustrates a perspective view of the bottom disc according to Fig. 7 DETAILED DESCRIPTION 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 paperboard sealing discs 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.

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.

The packaging container 1 comprises a container body 2 having a container wall 3 extending between an upper end 4 with an upper body opening 5’ and a bottom end 6 with a bottom body opening 5” in a height direction H. The container wall 3 has an inner surface 7 facing towards an inner compartment 9 in the packaging container 1 and an outer surface 8 facing away from the inner compartment 9. The container body 2 is made from paperboard material as defined herein.

The packaging container 1 furthermore comprises an inner partly or fully removable transport closure 18, i.e. not being a sealing disc 10 as disclosed herein in the packaging container 1 disclosed in figs. 1 and 2, forming a cross-sectional seal between the inner compartment 9 in the container body 2 and the upper body opening 5’, as shown in fig. 2. The packaging container 1 also comprises a closure arrangement comprising a lid 16 and a sealing disc 10, in the form of a bottom disc, sealing the bottom body opening 5”, the sealing disc 10 being defined by outer edges 30. As shown in fig. 2, the sealing disc 10 also comprises a sealing disc border 11 surrounding a sealing disc base portion 12. The border 1 1 is shaped before insertion and projects out of a main plane of the sealing disc 10 to form a flange 13 aligned with the inner surface 7 of the container wall 3. The flange is sealed against the inner surface 7. The sealing disc 10 may be attached by welding, such as by high frequency welding, to the inner surface 7 of the container wall 3 to ensure a tight seal between the flange 13 of the sealing disc 10 and the inner surface 7 of the container wall 3. While the sealing disc may be made from any suitable material such as paperboard, plastic or metal, paperboard sealing discs may generally be preferred.

The sealing disc 10 comprises distance elements 14 arranged side-by-side in the sealing disc border facing the inner surface 7 of the container wall 3. The distance elements 14 have a height h in a direction perpendicular to the height direction H of the container wall 3. The illustrated distance elements 14 are elongated distance elements extending from the sealing disc inner folding edge 31 to the outer edges 30, forming air conveying passages 15 in the form of air conveying channels 15 between the distance elements 14. The air conveying channels 15 have a width of between 1 and 20 mm, which corresponds to the width between the adjacent distance elements 14, and the purpose of the air conveying channels 15 is to provide air passage to control the pressure level within the inner compartment 9 of the packaging container 1 during assembly of the packaging container 1. The air passage thus extends from the sealing disc inner folding edge 31 to the outer edges 30, thus forming a channel out from the inner compartment 9 before attaching the flange 13 to the inner surface 7 of the container wall 3. After attachment of the flange 13 to the inner surface 7 of the container wall 3, the distance elements 14 are compressed such that an air-tight seal is formed between the flange 13 and the inner surface of the container wall 3. The sealing disc 10 shown in fig. 2 is, in addition to the distance elements 14, provided with reinforcing elements 19 at the sealing disc base portion 12, which improves the stability of the sealing disc 10. The reinforcing elements 19 may be embossed lines and/or dotted embossed lines in the sealing disc 10, alternatively, the reinforcing elements 19 may be reinforcing strips of material or reinforcing fold lines forming inwardly disposed ridges. As shown in fig. 2, the packaging container 1 may, furthermore, be provided with a reinforcement rim 20. The bottom reinforcement rim 20 may be joined to the inner surface 7 of the container wall 3 by welding such that a more reliably sift-proof join between the rim 20 and the container wall 3 can be achieved, than with an adhesive seal.

In figs. 1 and 2 the packaging container is furthermore provided with an upper reinforcing rim (not shown) which is attached, e.g. by welding, to the inner surface of the container wall 3 at the upper body opening 5’ and a frame structure 22, which may be mechanically connected with the upper reinforcing rim. The frame structure 22 may then serve to provide features such as a lid hinge. The frame structure 22 is in figs. 1 and 2 provided with locking elements 23 for retaining the lid 16 in a closed position over the access opening.

The application of a bottom reinforcing rim 20 to the bottom end of the packaging container, an upper reinforcing rim to the upper body opening 5' and a frame structure 22 is optional for the packaging container disclosed herein.

Fig. 3 shows a sealing disc 10, such as a bottom disc or a transport closure, in a flat and unfolded condition and provided with optional folding lines 21 for facilitated folding, such as when the sealing disc 10 is inserted into the bottom body opening 5”, or alternatively into the upper body opening 5’. The sealing disc 10 has a modified rectangular shape with curved edge portions 25 with first and second longitudinal opposing side portions 26, 27 and first and second transverse opposing side portions 28, 29 extending between the curved edge portions 25. The first and second longitudinal opposing side portions 26, 27 extending in a longitudinal direction y and the first and second transverse opposing side portions 28, 29 extending in a transverse direction x. As illustrated in this figure, each of the curved edge portions 25 are free from distance elements 14. The fact that the curved edge portions 25 are free from distance elements 14 improves the seal between flange 13 and the inner surface 7 as it prevents wrinkles to form adjacent to the distance elements 14 in the border when folding the outer edge portion 11 to form a flange 13. This may otherwise impair the seal between the flange 13 of the sealing disc 10 against the inner surface 7 of the container wall 3.

Fig. 4 shows the sealing disc 10, such as a bottom disc or a transport closure, when the border 11 has been flexed to form a flange 13, as during insertion into the packaging container 1. The sealing disc border 11 have been flexed along the folding lines 21, forming a sealing disc inner folding edge 31, shown in fig. 3, and projects out of a main plane of the sealing disc 10 to form a flange 13. The sealing disc 10 further comprises distance elements 14 having a height h, and which protrude towards the inner surface 7 of the container wall 3 when the sealing disc has been introduced into either the bottom body opening 5" or alternatively into the upper body opening 5'. The distance elements 14 extend from the sealing disc inner folding edge 31 to the outer edges 30 forming air conveying channels 15 between the distance elements 14. It should however be understood that the distance elements 14 may also be in the form of dots and shorter distance elements 14, as long as air conveying passages are formed between the distance elements 14. The sealing disc 10 is additionally provided with reinforcing elements 19 in the sealing disc base portion 12, which further improves the stability of the sealing disc 10. The reinforcing elements 19 are embossed lines forming inwardly disposed ridges. The distance elements 14 in this figure extend to the sealing disc inner folding edge 31. However, the distance elements 14 may of course also be shorter and extend about 1 mm, or between from 1 to 3 mm from the sealing disc inner folding edge 31. In fig. 5 the height h of the distance elements 14, as measured from the inner surface of the sealing disc, is equal to or larger than the thickness T of the sealing disc 10.

Fig. 5 is a cross sectional view of the sealing disc 10 according to fig. 4 along the line V-V, wherein the height h, as measured from the inner surface of the sealing disc 10, of the distance elements 14 is at least 0.005 mm. The air conveying channels have a width of between 0.5 and 8 cm, or between 0.5 and 5 cm. This ensures that the air conveying channels 15 provided between the distance elements 14 will provide an air passage to control the pressure level within the inner compartment of the packaging container during assembly of the packaging container, and specifically during the final sealing step after the packaging container 1 has been filled with the bulk solids.

Fig. 6 illustrates the sealing disc 10 from figs. 4 and 5 shown from the side facing away from the inner compartment 9.

Fig. 7 illustrates a sealing disc 10 with first and second longitudinal opposing side portions 26, 27 and first and second transverse opposing side portions 28, 29 extending between curved edge portions 25. The sealing disc 10 is provided with distance elements 14 on the inner surface extending continuously over the sealing disc base portion 14 and between each of the opposing sealing disc side portion at the first and second longitudinal side portions 26, 27. The curved edge portions 25 are free from distance e!ements14.

Fig. 8 is a cross sectional view of the sealing disc 10 according to fig. 7 along the line VIII-VIII, wherein the height h, as measured from the inner surface of the sealing disc 10, of the distance elements 14 is at least 0.03 mm, such as from 0.03 to 3 mm. The air conveying channels have a width of between from 1 to 20 mm, or between from 3 to 10 mm. This contributes to that the air conveying channels 15 provided between the distance elements 14 provides an air passage to control the pressure level within the inner compartment of the packaging container.

Fig. 9 illustrates the sealing disc 10 according to fig. 7 shown from the side facing away from the inner compartment 9.

It is to be understood that the figures should not be seen as limiting to the configuration of the sealing disc. The sealing disc may thus for example be provided with more or fewer distance elements, larger or smaller flange, no reinforcement elements in the base portion, or alternatively a different type of reinforcements in the base portion.

Claims

1. A paperboard sealing disc (10) for use in a paperboard packaging container (1) for bulk solids, said packaging container (1) comprising a container body (2) with an upper end (4) with an upper body opening (5’) and a bottom end (6) with a bottom body opening (5”), a container wall (3) extending between said upper end (4) and said bottom end (6) in a height direction (H), said container wall (3) having an inner surface (7) facing towards an inner compartment (9) in said packaging container (I) and an outer surface (8) facing away from said inner compartment (9), said sealing disc (10) being intended for sealing said upper body opening (5’) or said bottom body opening (5"), said sealing disc (10) comprising a sealing disc border (I I) surrounding a sealing disc base portion (12), wherein said border (11) is delimited from said disc base portion (12) by a sealing disc inner folding edge (31), said sealing disc border (11) being intended to be flexed at said inner folding edge (31) forming a flange (13) projecting out of a main plane of said sealing disc (10) and being aligned with and sealed to said inner surface (7) of said container wall (3), characterized in that said sealing disc (10) comprises one or more distance element(s) (14) being arranged in said sealing disc border (11) and facing said inner surface (7) of said container wall (3) when said sealing disc (10) is arranged in said upper body opening (5’) or said bottom body opening (5") and aligned with said inner surface (7) of said container wall (3), said distance element(s) (14) having a height (h), as measured from the surface of said sealing disc border (11).

2. The sealing disc (10) according to claim 1, characterized in that said sealing disc (10) comprises two or more distance elements (14) arranged side-by-side in said bottom disc border (11).

3. The sealing disc (10) according to claim 2, characterized in that said distance elements (14) are provided with a distance from each other of from 1 to 20 mm, as measured between each of the distance elements (14).

4. The sealing disc (10) according to any one of claims 1 - 3, characterized in that said distance element(s) (14) are provided at said sealing disc inner folding edge (31) or with a distance of no more than 1 mm from said sealing disc inner folding edge (31).

5. The sealing disc (10) according to any one of the preceding claims, characterized in that said one or more distance element(s) (14), is/are elongated distance element(s) (14) having have a length of 1 mm or more.

6. The sealing disc (10) according to any one of the preceding claims, characterized in that said height (h) of said distance elements (14) is at least 0.005 mm, such as from 0.005 mm to 3 mm.

7. The sealing disc (10) according to any one of the preceding claims, characterized in that said sealing disc (10) has a longitudinal direction (y) and a transverse direction (x) perpendicular to said longitudinal direction (y), and first and second longitudinal opposing border (26, 27) extending in said longitudinal direction (y), and first and second transverse opposing border (28, 29) extending in said transverse direction (x), wherein said first and said second longitudinal opposing border (26, 27) and said first and said second transverse opposing border (28, 29) extend between curved corner portions (25), said distance elements(14) being disposed along said first and second longitudinal opposing border (26, 27) and extending in said transverse direction (x).

8. The sealing disc (10) according to claim 7, characterized in that said curved corner portions are free from said distance elements (14).

9. The sealing disc (10) according to any one of the preceding claims, characterized in that said one or more elongated distance element(s) (14) extend across said sealing disc (10).

10. The sealing disc (10) according to any one of the preceding claims, characterized in that said distance element(s) (14) comprises or consist of embossed dots or lines in said sealing disc (10).

11. The sealing disc (10) according to any one of the preceding claims, characterized in that said sealing disc (10) comprises reinforcing elements provided in, and extending only within, said sealing disc base portion (12).

12. The sealing disc (10) according to any of the preceding claims, characterized in that said sealing disc (10) is a bottom disc.

13. The sealing disc (10) according to any one of claims 1-11, characterized in that said sealing disc (10) is an inner partly or fully removable transport closure (10') intend to form a cross-sectional seal between said inner compartment (9) in said container body (2) and said upper body opening (5’).

14. A method of producing and filling a paperboard packaging container (1) with bulk solids (25), characterized in that the method comprises the steps of: a) forming a tubular container body (2) from a paperboard sheet (2'), said container body having an upper end (4) with an upper body opening (5’) and a bottom end (6) with a bottom body opening (5") and a container wall (3) extending in a height direction (H) of said packaging container (1) between said upper body opening (5’) and said bottom body opening (5"), said container wall (3) having an inner surface (7) and an outer surface (8), an upper end edge and an bottom end edge; b) attaching an inner partly or fully removable transport closure (18) to said inner surface (7) of said container wall (3) and/or sealing said upper body opening (5') with a container lid (16) and; c) presenting said container body (2) to a filling station with said bottom body opening (5”) of said container body (2) directed upward in a vertical direction; d) filling bulk solids (25) into said container body (2) through said upwardly directed bottom body opening (5”); e) closing said bottom body opening (5") by pressing a paperboard sealing disc (10) into said bottom body opening (5”), said paperboard sealing disc (10) comprising a sealing disc border (11) surrounding a sealing disc base portion (12), said sealing disc border (11) being flexed towards the upper end (4) in the height direction (H) and forming a flange (13), said sealing disc (10) comprising one or more distance element(s) (14) being arranged in said sealing disc border (11) on an inner surface facing said container wall (3), said distance elements (14) having a height (h) in a direction perpendicular to said height direction (H) of said container wall (3), defining two or more air conveying passages (15) at each side of said one or more distance elements (14) and between said inner surface of said sealing disc border (11) and said container wall (3), and; f) attaching said flange (13) to said inner surface (7) of said container wall (3).

15. A method of producing and filling a paperboard packaging container (1) with bulk solids (25), characterized in that the method comprises the steps of: a) forming a tubular container body (2) from a paperboard sheet (2’), said container body having an upper end (4) with an upper body opening (5’) and a bottom end (6) with a bottom body opening (5") and a container wall (3) extending in a height direction (H) of said packaging container (1) between said upper body opening (5’) and said bottom body opening (5"), said container wall (3) having an inner surface (7) and an outer surface (8), an upper end edge and an bottom end edge; b) closing said bottom body opening (5"); c) presenting said container body (2) to a filling station with said upper body opening (5') of said container body (2) directed upward in a vertical direction; d) filling bulk solids (25) into said container body (2) through said upwardly directed upper body opening (5’); e) closing said upper body opening (5’) by pressing a paperboard sealing disc (10) into said upper body opening (5’), said paperboard sealing disc (10) comprising a sealing disc border (11) surrounding a sealing disc base portion (12), said sealing disc border (11) being flexed towards the upper end (4) in the height direction (H) and forming a flange (13), said sealing disc (10) comprising one or more distance element(s) (14) being arranged in said sealing disc border (11) on an inner surface facing said container wall (3), said distance elements (14) having a height (h) in a direction perpendicular to said height direction (H) of said container wall (3), with two or more air conveying passages (15) being defined on each side of said distance elements (14) and between said inner surface of said sealing disc border (11) and said container wall (3), and; f) attaching said flange (13) to said inner surface (7) of said container wall (3).

16. The method of producing and filling a paperboard packaging container (1) with bulk solids (25) according to claims 14 or 15, characterized in that said sealing disc (10) comprises two or more distance elements (14) arranged side-by-side in said sealing disc border (11) and defining at least one air conveying passages (15) between said distance elements (14), said air conveying passage (15) between said distance elements (14) having a width of from 1 to 20 mm.

17. The method of producing and filling a paperboard packaging container (1) with bulk solids (25) according to any one of claims 14-16, characterized in that said height (h) of said distance elements (14) is at least 0.005 mm, such as from 0.005 mm to 3 mm, as measured from said inner surface of said sealing disc border (11).

18. The method of producing and filling a paperboard packaging container (1) with bulk solids (25) according to any one of claims 14-17, characterized in that said sealing disc (10) is pre-formed and already flexed and shaped to a flange (13) before being pressed into said upper or bottom body opening (5’, 5").