Composite Paperboard Container With A Rim Comprising Fibers, And A Method For Producing Such A Container

Abstract

The present disclosure relates to a composite paperboard container for bulk solids having a tubular body being closed at a bottom end over a container bottom opening opposite a container top opening at a top end. The rim is attached at a connecting portion of the rim to an end portion of the tubular body along an end edge of the tubular body. The connecting portion of the rim has a distal edge. The rim is a molded rim comprising pulp fibers. The tubular body is connected by welding to the connecting portion of the rim and the distal edge of the rim is located at a distance from the end edge of the tubular body.

Claims

1. A composite paperboard container for bulk solids, the composite paperboard container comprising a tubular body being closed at a bottom end over a container bottom opening opposite a container top opening at a top end of the tubular body, the tubular body having an inner surface facing towards an interior of the container body and an outer surface facing away from the interior of the container body, the tubular body extending in a longitudinal direction, the composite container comprises a rim surrounding one of the container top opening and the container bottom opening, the rim being attached at a connecting portion of the rim to an end portion of the tubular body along an end edge of the tubular body, the connecting portion of the rim has a distal edge, the tubular body being made from a laminate sheet material comprising a carton substrate layer and a thermoplastic welding layer, wherein the rim is a molded rim comprising pulp fibers, the tubular body is connected by welding to the connecting portion of the rim and the distal edge of the rim is located at a distance from the end edge of the tubular body of at least 4 mm as seen in the longitudinal direction of the tubular body.

2. The composite paperboard container according to claim 1, wherein the rim is an inner rim and the composite paperboard container comprises a lid component being a molded lid component comprising pulp fibers, the lid component including an outer rim part and a lid part, wherein the outer rim part and the lid part are moulded in one piece, the outer rim part being connected to the lid part via a hinge portion and wherein the outer rim part connectable to the inner rim.

3. The composite paperboard container according to claim 1, wherein the composite paperboard container is free from plastic components attached to the tubular body.

4. The composite paperboard container according to claim 1, wherein rim has a density within the range of from 0.2 to 1.5 kg/dm3.

5. The composite paperboard container according to claim 1, wherein the rim comprises a U-shaped or a square edge U-shaped track portion comprising a first and a second side wall section and a bottom section facing the end edge of the tubular body, and wherein a draft angle, between the bottom section and the first side wall section, is within the range of from zero to ten degrees.

6. The composite paperboard container according to claim 1 wherein the rim comprises an L-shaped connecting portion comprising a first side wall section and a bottom section facing the end edge of the tubular body, and wherein a draft angle, between the bottom section and the first side wall section, is within the range of from zero to ten degrees.

7. The composite paperboard container according to claim 5, wherein the rim comprises a guiding side wall section extending from the first side wall section, the guiding side wall section being an inclined wall section with an increasing distance to the tubular body as seen from the end edge of the tubular body and in the longitudinal direction of the tubular body.

8. The composite paperboard container according to claim 1, wherein the thermoplastic welding layer comprises or consists of a polyethylene layer.

9. The composite paperboard container according claim 1, wherein the thermoplastic welding layer has a basis weight of at least 15 g/m.sup.2 on the laminate sheet material.

10. The composite paperboard container according claim 1, wherein the laminate sheet material comprises a metallic foil layer.

11. A method of producing a composite paperboard container for bulk solids, the method comprising the steps of; a) bending a paperboard laminate sheet material comprising a carton substrate layer and a thermoplastic welding layer into a tube, the tube having a longitudinal direction, a radial direction perpendicular to the longitudinal direction, closing the tube in the longitudinal direction by joining overlapping or abutting side edges of the paperboard material thereby forming a tubular body, the tubular body having an inner surface facing towards an interior of the tubular body and an outer surface facing away from the interior of the tubular body; b) imparting a predetermined cross-sectional shape to said tube; c) closing the tubular body at a bottom end over a container bottom opening opposite a container top opening at a top end of the tubular body; d) providing pulp fibers into a molding tool thereby forming a three-dimensionally shaped rim component comprising pulp fibers, the rim comprising a connecting portion having a distal edge; e) providing the rim to an end portion of the tubular body along an end edge of the tubular body so that the rim surrounds one of the container top opening and the container bottom opening, such that that the distal edge of the rim connecting portion is located at a distance from the end edge of the tubular body within the range of at least 4 mm as seen in the longitudinal direction of the tubular body; and f) attaching the connecting portion of the three-dimensionally formed container component to the end portion of the tubular body by welding, thereby forming the composite paperboard container.

12. The method according to claim 11, wherein step d) include forming the rim comprising a U-shaped or a square edge U-shaped track portion, the U-shaped or square edge U-shaped track portion comprising a first and a second side wall section and a bottom section and wherein step e) includes arranging the rim such that the bottom section faces the end edge of the tubular body.

13. The method according to claim 11, wherein the rim comprises an L-shaped connecting portion comprising a first side wall section and a bottom section facing the end edge of the tubular body, and wherein a draft angle, between the bottom section and the first side wall section, is within the range of from zero to ten degrees.

14. The method according to claim 12, wherein a draft angle, between the bottom section and the first side wall section, is within the range of from zero to ten degrees.

15. The method according to claim 11, wherein the rim has a density within the range of from 0.2 to 1.5 kg/dm.sup.3.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0044] FIG. 1 illustrates a composite paperboard container according to the present disclosure;

[0045] FIG. 2 illustrates a paperboard blank;

[0046] FIG. 3 illustrates folding of the paperboard blank to a tubular body;

[0047] FIGS. 4-5 illustrate inserting a paperboard disc into the tubular body thereby forming a container bottom;

[0048] FIG. 6 illustrates molding of pulp fibers to form a rim and lid component;

[0049] FIG. 7 illustrates the molded rim comprising an inner rim component and an outer rim and lid component;

[0050] FIG. 8 illustrates attaching the inner rim component to the tubular body by welding; and

[0051] FIG. 9 illustrates attaching the outer rim and lid component to the inner rim component and thereby forming a composite paperboard container prepared by the method according to the present disclosure.

DETAILED DESCRIPTION

[0052] It is to be understood that the drawings are schematic and that individual components, such as layers of materials and container components are not necessarily drawn to scale. The composite paperboard container and the steps in the method of forming a composite paperboard container shown in the figures are provided as examples only and should not be considered limiting to the invention. Accordingly, the scope of the invention is determined solely by the scope of the appended claims.

[0053] FIG. 1 illustrates a composite paperboard container 1 for bulk solids, the composite paperboard container 1 comprising a tubular body 2 being closed at a bottom end 3 over a container bottom opening 4 opposite a container top opening 5 at a top end 6 of the tubular body 2. The tubular body 2 has an inner surface 7 facing towards an interior of the container body 2 and an outer surface 8 facing away from the interior of the container body 2. The tubular body 2 extends in a longitudinal direction L between the bottom end 3 and the top end 6. The composite container 1 comprises a rim 9 surrounding the container top opening 5. The rim 9 is a molded inner rim 9a comprising pulp fiber, such as softwood pulp fibers. The inner rim 9a is attached to the tubular body 2 by welding a connecting portion 11 of the inner rim 9a to an end portion 10 of the tubular body 2 along an end edge 12 of the tubular body 2. The connecting portion 11 of the inner rim 9a has a distal edge 11a, the rim is located at a distanced from the end edge 12 of the tubular body within the range of from 4 mm to 50 mm.

[0054] The composite container 1 furthermore comprises a lid component including an outer rim part 9b and a lid part 9c. The outer rim part 9b and the lid part 9c are moulded in one piece. The outer rim part 9b is connected to the lid part 9c via hinge portions 9d. The outer rim part 9b is connected to the inner rim 9a, the outer rim part 9b may be connected by a snap-on function, a slide-in connection, by means of adhesive or any other suitable means. The lid component is made from the same material as the inner rim 9a.

[0055] The inner rim 9a comprises a square edge U-shaped track portion 13, as seen in a cross-section view, comprising a first and a second side wall section 13a,13b and a bottom section 13c facing the end edge 12 of the tubular body 2. The first side wall section 13a corresponds to the connecting portion 11 of the inner rim 9a. However, the inner rim may have an L-shaped cross-section, with a first side wall section corresponding to the connecting portion of the rim and a bottom section arranged to face the end edge 12 of the tubular body 2.

[0056] The tubular body 2 is made from a laminate sheet material comprising a carton substrate layer and a thermoplastic welding layer 14.

[0057] FIGS. 2 to 9 show a method of producing a composite paperboard container 1 for bulk solids. FIG. 2 illustrates a paperboard laminate sheet material 2″ comprising a carton substrate layer and a thermoplastic welding layer 14. The laminate sheet material 2″ has opposing side edges 16,17. FIG. 3 shows a first step a) of bending the paperboard laminate sheet material 2″ into a tube 2′, the tube 2′ having a longitudinal direction L, and closing the tube 2′ in the longitudinal direction L by joining abutting side edges 16,17 of the paperboard material 2″ and thereby forming a tubular body 2. The join between the side edges 16,17 may be covered by a sealing strip. The side edges 16,17 may alternatively be joined being overlapping. The tubular body 2 formed has an inner surface 7 facing towards an interior of the tubular body 2 and an outer surface 8 facing away from the interior of the tubular body 2. The thermoplastic welding layer 14 of the laminate sheet material is arranged on the inner surface 7 of the tubular body 2. The tube is shaped to have a predetermined cross-sectional shape. In the example shown in the figures, the cross-sectional shape is a modified rectangular shape with rounded corners. It is to be understood that the tubular body may have any useful cross-sectional shape such as circular shape, oval shape, or any polygonal or modified polygonal shape such as triangular shape, square shape, pentagonal shape, etc.

[0058] FIGS. 4 and 5 illustrate a step c) of closing the tubular body 2 at a bottom end 3 over a container bottom opening 4 opposite a container top opening 5 at a top end 6 of the tubular body 2. The bottom opening 4 is closed by pressing by pressing a paperboard bottom disc 18 into the tube at the bottom end 3. The bottom disc 18 has a peripheral flange 18a being flexed towards the bottom end 3 in the longitudinal direction L. The flexed peripheral flange 18a may be attached to the inner surface 7 of the tubular body 2 for example by welding. The paperboard bottom disc 18 may be constituted of a laminate sheet material comprising a carton substrate layer and a thermoplastic welding layer. A bottom rim may be applied to the bottom end 3 of the tubular body, the bottom rim may be a molded rim comprising pulp fibers according to the present disclosure and may be applied by welding according to the present disclosure or may be adhesively attached.

[0059] FIG. 6 illustrates a step of forming the lid component including the outer rim part 9b and the lid part 9c. The molded outer rim and lid part are formed by providing softwood pulp fibers, such as in the form of a pulp slurry, in a molding tool 15. The molding tool 15 comprises a female molding tool component 15a and a mating male molding tool component 15b between which the pulp fibers are pressed to form a three-dimensionally shaped lid component comprising pulp fibers. The inner rim 9a (illustrated in FIG. 7 being molded in a corresponding manner).

[0060] FIG. 7 illustrates an inner rim 9a and a lid component including an outer rim part 9b and a lid part 9c molded in one piece and the outer rim component 9b being connected to the lid component 9c via two hinge portions 9d.

[0061] The inner rim 9a has a square U-shaped track portion 13, as seen in a cross-section view, comprising a first and a second side wall section 13a,13b and a bottom section 13c, intended to face the end edge 12 of the tubular body 2. The first side wall section 13a corresponds to the connecting portion 11 of the inner rim 9a. However, the rim may equally be of an L-shape, with a first side wall section corresponding to the connecting portion of the rim and a bottom section intended to face the end edge 12 of the tubular body 2. A draft angle α, between the bottom section 13c and the first side wall section 13a, is within the range of from zero to ten degrees.

[0062] FIG. 8 illustrates a step of attaching the inner rim 9a by means of welding the inner rim 9a to the end portion 10 of the tubular body 2 along the end edge 12 of the tubular body 2, so that the inner rim 9a surrounds the container top opening 5. The welding is in this figure performed by a welding unit 19 comprising an induction coil 19a and a press plunger 19b.

[0063] The welding unit 19 comprises a high frequency induction welding unit comprising an induction coil 19a. The press plunger 19b comprises an expandable welding tool 51 which is transformable between an unexpanded state, and a radially expanded state.

[0064] In the expanded state, a cross-sectional area (footprint) delimited by the outer circumference of the welding tool 51 is larger than in the unexpanded state of the welding tool 51.

[0065] When the press plunger 19b is inserted into the tubular body 2 with the welding tool 51 in the attachment position for the inner rim 9a, the welding tool 51 is transformed to the expanded state.

[0066] In the expanded state of the welding tool 51, an edge portion of the outer circumference of the welding tool 51 contacts the inner rim 9a which is inserted into the tubular body 2 and exerts pressure on the inner rim 9a such that it is pressed against the inside of the tubular body 2 and can be induction welded to the inside of the tubular body 2 by activating the induction coil 19a.

[0067] FIG. 9 illustrates when the inner rim 9a is attached to the end portion 10 of the tubular body 2 and the step of attaching the outer rim and lid parts 9b,9c to the inner rim 9a by a snap-fit attachment.