GB2548399A

GB2548399A - Container closure

Info

Publication number: GB2548399A
Application number: GB1604607.0A
Authority: GB
Inventors: William Myerscough Martin
Original assignee: Frugalpac Ltd
Current assignee: Frugalpac 2 Ltd
Priority date: 2016-03-18
Filing date: 2016-03-18
Publication date: 2017-09-20
Also published as: GB201604607D0

Abstract

A rim element 10 for a container (e.g. for paint) has an annular collar 32 and an engagement projection 62, 64. The rim element 32 can create a seal with a lid 76, e.g. allowing the container 10 of paperboard or cardboard to be recycled. The container may have a flexible liner (182, fig 4) for paint. The rim may be attached to the container by applying a force parallel to an axis of a tubular side wall of the container, so that the engagement projection 62, 64 of the rim presses into an inner side surface of the container wall, to hold the rim in place. Many projections 62, 64 may extend circumferentially around the collar 32, creating a tight fit with the container, or may engage in a recess (458, fig 8) of the container. Projections 62, 64 may be a helical thread. The rim may be removed from the container by applying a non-parallel force to an axis of the container, e.g. by twisting. This allows a polymeric rim to be removed from the container for recycling, when the rim is contaminated by any remaining paint. The rim 10 may be a unitary element.

Description

Container Closure

BACKGROUND a. Field of the Invention

This invention relates to rim elements for containers, liner assemblies for containers and to containers including a separable rim element. This invention further relates to a method of manufacturing a container and to a method of disposal of a container. b. Related Art

There is a general desire and need to reduce the amount of waste that is produced and a drive to recycle as much as possible. One particular area that is receiving much attention is packaging.

Containers for hazardous liquids, such as paints, are difficult to dispose of in an environmentally safe manner and very few containers are recycled due to contamination by the paint, oil or other similar substance.

Known paint pots and similar containers filled with environmentally hazardous liquids are typically made from a semi-rigid plastics material or from metal. After use, the pot remains contaminated with paint residue or similar and the entire container must be disposed of in a suitable manner depending on the type of hazardous liquid. Often the containers end up in a specialist landfill. However, the cost associated with dealing with these containers means that it is becoming increasingly difficult to dispose of them in a convenient and cost effective way.

It is known to provide containers for liquids such as paint comprising a main body formed of paperboard and having an inner plastics lining. These containers have the advantage that the contaminated plastics lining can be separated from the paperboard shell for disposal once the contents of the container have been used. However, there are a number of disadvantages with these containers.

Typically, the contents of the container are not used all at one time and it is necessary, therefore, to be able to repeatedly reseal the container and prevent the liquid contents evaporating or drying between uses. It is often difficult, however, to form a good seal, i.e. a liquid-proof seal, between a container formed of paperboard or laminated paperboard and a lid if it is necessary to be able to repeatedly remove the lid from the container.

For example, it is known to seal a paper cup or container with a foil lid that is heat sealed to the rim of the container. These lids can provide a good seal; however, they are designed for single use and once they have been removed, the container cannot be resealed. It is also known to provide plastic lids that snap fit over the rolled rim of a typical paper cup or container, such as those lids that are provided with a drinking hole for disposable coffee cups. These lids can be repeatedly used to close the container; however, they do not provide a good seal. As such, any liquid contents of the container may leak out through small gaps between the rim of the container and the lid. This is especially problematic near any overlapping seams in the container due to the change in thickness of the side wall and rim in this region.

Furthermore, the method of manufacturing cardboard containers including an inner lining can be quite complex, especially if it is desired to form a good seal with a lid and to be able to fully separate the cardboard and lining after use.

It is, therefore, an object of the present invention to provide a container that overcomes at least one of the disadvantages of prior art containers.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention there is provided a rim element for a container, the rim element being a unitary element made of a polymeric material, and the rim element comprising: an annular collar having a radially inner surface and a radially outer surface, an external diameter of the collar being sized to be received within an opening of said container; an aperture defined by the inner surface of the collar; a flange extending radially outwardly from the outer surface at a first end of the collar; and an engagement feature comprising one or more projections extending from the outer surface, the engagement feature extending circumferentially around the collar.

In use, the rim element is retained on the side wall of a container by means of complementary engagement features. A first engagement feature is provided on a part of the rim element and a second engagement feature is formed in the side wall of the container. In some embodiments, the second engagement feature is formed by the first engagement feature when the rim element is attached to the side wall. In particular the first engagement feature may apply a force to the side wall in a radially outward direction so as to create an indent or groove in the inner surface of the side wall.

To construct a container, the rim element is preferably inserted into an end of a tubular side wall of the container by applying an axial force to the rim element and/or side wall. To ease insertion of the rim element the projection preferably comprises an engagement surface facing generally away from the flange and extending at an angle to the outer surface of the collar.

In preferred embodiments the projection has a tapered cross-sectional shape such that the projection extends outwardly to an apex or ridge of the projection. This makes it easier for the projection to press into the side wall of the container and form a corresponding indent or groove.

In preferred embodiments the projection on the rim element comprises a helical rib. It is particularly preferable if a first end of the helical rib contacts the flange.

The collar has a second end, opposite the first end. Preferably the projection does not extend all the way to the second end. A region of the collar is, therefore, defined between a second end of the projection and the second end of the collar. A lining of the container may be attachable to this region.

The rim element preferably further comprises a skirt portion extending from the flange. The skirt portion typically extends from a radially outer edge of the flange in a direction towards a second end of the collar. Preferably a recess defined between the skirt portion and the collar is configured and sized to receive an edge of a side wall of said container.

The rim element may further comprise a securing member configured to engage with a lid of said container. The securing member will typically be annular and the securing member preferably extends from the first end of the collar or from the flange. The securing member is preferably configured to enable repeated engagement with a lid of the container.

In some embodiments the rim element may comprise a base plate extending across the aperture.

According to a second aspect of the present invention there is provided a liner assembly for a container comprising: a rim element including an annular collar having a radially inner surface and a radially outer surface, an aperture defined by the inner surface of the collar, a flange extending radially outwardly from the outer surface at a first end of the collar, and an engagement feature comprising one or more projections extending from the outer surface, the engagement feature extending circumferentially around the collar; and a flexible lining including a tubular portion having an annular edge, the lining being attached to the collar of the rim element around the annular edge proximate a second end of the collar.

The lining is preferably attached to the outer surface of the collar. In preferred embodiments the lining is made of a polymeric material. In some embodiments the lining is in the form of a pouch having a closed end. The lining is preferably heat welded to the collar.

According to a third aspect of the present invention there is provided a container comprising: a tubular side wall made from paperboard or cardboard, the side wall including an annular edge at a first end of the side wall; and a rim element attached to the side wall, the rim element including an annular collar having a radially inner surface and a radially outer surface, an aperture defined by the inner surface, a flange extending radially outwardly from the outer surface at a first end of the collar, and an engagement feature comprising one or more projections extending from the outer surface, the engagement feature extending circumferentially around the collar, wherein the flange extends over the annular edge of the side wall and the collar extends away from the annular edge over a part of an inner surface of the side wall, and wherein the one or more projections extend into a part of the side wall to retain the rim element on the side wall.

In preferred embodiments the projection comprises a helical rib and a corresponding helical groove is formed in the side wall.

The rim element may comprise a skirt portion extending from the flange. When attached to the side wall, this skirt portion extends over an outer surface of the side wall.

The container preferably comprises a flexible lining including a tubular portion having an annular edge. The lining is attached to the collar of the rim element around the annular edge proximate a second end of the collar.

The lining preferably conforms to the shape of the side wall. In some embodiments the lining is adhered to the side wall.

The container may additionally comprise a base at a second end of the side wall. In embodiments in which the container includes a side wall, the lining preferably conforms to the internal shape of the side wall and base.

In some embodiments the container may include a first rim element attached to the first end of the side wall and a second rim element attached to a second end of the side wall.

The container of the present invention may additionally comprise a lid. In these embodiments, the rim element may include a securing member configured for engagement with the lid such that the lid may be repeated engaged with and detached from the rim element.

According to a fourth aspect of the present invention there is provided a method of assembling a container comprising: aligning an annular collar of a rim element with a first end of a tubular side wall, the side wall being made from paperboard or cardboard; applying a force to the rim element parallel to an axis of the tubular side wall to insert the collar such that the collar extends over a part of an inner surface of the side wall; and continuing to apply a force to the rim element until a flange of the rim element contacts an annular edge at the first end of the side wall, wherein, once the rim element is fully inserted an engagement feature comprising one or more projections extending from an outer surface of the collar press into an inner surface of the side wall to retain the rim element on the side wall, the engagement feature extending circumferentially around the collar.

The engagement feature preferably comprises a helical rib projecting from the collar, and the helical rib presses into the inner surface of the side wall so as to form a helical groove that extends to the annular edge of the side wall.

The method may additionally comprise the step of bonding a flexible lining to the rim element before inserting the rim element in the end of the side wall.

According to a fifth aspect of the present invention there is provided a method of disassembling a container, the container comprising a rim element attached to a first end of an annular side wall, the rim element comprising a collar extending over an inner surface of the side wall and a flange in contact with an annular edge at the first end of the side wall, and the method comprising applying a force to the rim element to disengage an engagement feature projecting from an outer surface of a collar of the rim element from a complementary recess formed in an inner surface of the side wall, the direction of the force being non-parallel to an axis of the container.

Preferably the engagement feature comprises a helical rib projecting from the collar engaged in a complementary helical groove in the inner surface of the side wall, and the method comprises applying a rotational force to the rim element to unscrew the rim element from the side wall. The rotational force is applied so as to rotate the rim element about the axis of the container.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be further described by way of example only and with reference to the accompanying drawings, in which:

Figure 1 is a cross-sectional view of a container including a separable rim element according to a first preferred embodiment of the present invention;

Figure 2 is a detail cross-sectional view of the area circled in Figure 1;

Figure 3 is a side view of the rim element of Figure 1;

Figure 4 is a cross-sectional view showing a part of a liner assembly for a container according to a preferred embodiment of the present invention, the liner assembly including a rim element and a flexible lining;

Figure 5 is a cross-sectional view of a container including a separable rim element according to a second preferred embodiment of the present invention;

Figure 6 is a detail cross-sectional view of the area circled in Figure 3;

Figure 7 is a cross-sectional view of a container according to a further embodiment of the invention comprising a tubular side wall and a rim element attached to the side wall at opposite ends of the side wall; and

Figure 8 is a detail cross-sectional view of a part of a rim element including an engagement feature according to another embodiment of the invention.

DETAILED DESCRIPTION

Containers according to the present invention preferably comprise a paperboard or cardboard outer shell, a flexible polymeric lining and a rim element that is secured to the lining and engages with an upper edge of the shell. The rim element defines and surrounds an opening of the container and provides means for securing a lid or cover to the container to enclose an internal volume of the container.

Importantly, the configuration of the rim element enables the container to be manufactured quickly and easily, as well as enabling a user to remove the rim element and lining from the shell with minimal effort when it is desired to dispose of the container. This allows these parts to be disposed of or recycled separately.

In particular, the rim elements of the present invention include an engagement feature that engages with an internal surface of the cardboard shell to retain the rim element on the shell and subsequently permits the rim element to be disengaged or detached from the shell. The engagement feature is preferably configured such that the rim element may be inserted into the shell by applying a force to the rim element in a first direction and may be removed from the shell by applying a force to the rim element in a second direction, the second direction being non-parallel to the first direction.

Figures 1,2 and 3 illustrate a first preferred embodiment of a rim element 10 and a container 12 according to the invention. A main body 14 of the container 12 comprises a tubular side wall 16 and a base 18. The side wall 16 has a circular cross-sectional shape perpendicular to a longitudinal axis 20 of the main body 14. The side wall 16 extends between a first end 22 and a second end 24. The first end 22 includes an annular upper edge 26 of the main body 14 and, in this embodiment, defines an opening 28 of the main body 14.

The base 18 is attached to the side wall 16 at or proximate the second end 24 of the side wall 16. The base 18 may be attached to the side wall 16 at a distance from the second end 24 of the side wall 16 such that the second end 24 of the side wall 16 forms an annular foot of the container 12, as shown in Figure 1. In other embodiments the base 18 may extend over the second end 24 of the side wall 16.

The side wall 16 is made from a suitable paperboard or cardboard material. The material is preferably 100% paperboard or cardboard to aid recycling of the container 12. The side wall 16 is preferably a spiral-wound tube made using processes known in the art.

The rim element 10 comprises an annular collar 30 having an inner surface 32 and an outer surface 34. The collar 30 extends between first and second ends 36, 38, thereby defining an axis 40 of the rim element 10. The annular collar 30 has a circular cross-sectional shape perpendicular to the axis 40, and an external diameter of the collar 30 is substantially equal to or slightly smaller than an internal diameter of the side wall 16 of the main body 14. A flange 42 extends radially outwards from the first end 36 of the collar 30. The flange 42 comprises an annular member extending perpendicularly from the collar 30 to a radially outer edge 44. The flange 42 has opposite first and second faces 46, 48. A skirt 50 extends from the flange 42 at the radially outer edge 44. The skirt 50 extends from the first face 46 of the flange 42 in a direction towards the second end 38 of the collar 30. In this embodiment the skirt 50 extends substantially parallel to the collar 30. A recess 52 is, therefore, defined between an inner surface 54 of the skirt 50 and the outer surface 34 of the collar 30. A width of the recess 52 is defined by a distance between the skirt 50 and the collar 30 and a depth of the recess 52 is defined by a length of the skirt 50, i.e. the distance between a free edge 56 of the skirt 50 and the annular member of the flange 42. The length of the skirt 50 is typically substantially less than a length of the collar 30 between its first and second ends 36, 38.

An engagement feature 58 is located on and extends from the outer surface 34 of the collar 30. The engagement feature 58 comprises a projection 60 that extends radially outwardly from the collar 30. In this embodiment the engagement feature 58 is in the form of a rib or ridge 60 that extends circumferentially around the collar 30. The rib 60 includes a lower engagement surface 62 that faces generally in a direction towards the second end 38 of the collar 30 and an upper engagement surface 64 that faces generally in a direction towards the first end 36 of the collar 30. As shown most clearly in Figure 3 the rib 60 extends around the collar 30 following a spiral or helical path. The helical rib 60 may, therefore, be considered to be a male screw thread. The rib 60 has a substantially triangular cross-sectional shape. In particular, the lower engagement surface 62 of the rib 60 is angled with respect to the outer surface 34 of the collar 30, i.e. the lower engagement surface 62 is non-parallel and non-perpendicular to the outer surface 34. The lower engagement surface 62 typically lies at an angle of between 10° and 80° to the outer surface 34 of the collar 30. The lower engagement surface 62 is angled such that a radially outer edge of the lower engagement surface 62 is further from the second end 38 of the collar 30 than a radially inner edge. In this example the upper engagement surface 64 of the rib 60 is also angled with respect to the outer surface 34 of the collar 30, i.e. the upper engagement surface 64 is non-parallel and non-perpendicular to the outer surface 34.

The engagement feature 58 does not extend along the full length of the collar 30 between the first and second ends 36, 38. In particular, an attachment region 66 of the collar 30 is located at the second end 38 of the collar 30. The engagement feature 58 does not extend into the attachment region 66.

In this embodiment the rim element 10 further comprises an annular securing member 68. The securing member 68 extends from the first end 36 of the collar 30 in a direction substantially away from the second end 38 of the collar 30. An upper, free edge 70 of the securing member 68 includes a sealing lip 72. The sealing lip 72 extends inwardly from the securing member 68 and an inner surface 74 of the sealing lip 72 defines an opening 76 at an upper end of the rim element 10. The securing member 68 is configured to engage with a lid 78 of the container 12.

The rim element 10 is preferably a unitary element. In this embodiment the rim element 10 is made from a suitable, substantially rigid, polymeric material.

The rim element 10 is configured to engage with the first end 22 of the side wall 16 of the container 12. To assemble the container 12, the second end 38 of the collar 30 is aligned with the opening 28 defined by the upper edge 26 of the main body 14. A force is then applied to the rim element 10 in a direction parallel to the longitudinal axis 20 of the main body 14 and in a direction towards the second end 24 of the main body 14. The dimensions of the collar 30, and in particular the external diameter of the collar 30, are such that there is a tight push fit of the collar 30 in the end of the tubular side wall 16. The angled lower engagement surface 62 of the engagement feature 58 allows the collar 30 to be pushed into the side wall 16 with some elastic deformation of the collar 30 and/or the side wall 16.

The rim element 10 is pushed into the end of the side wall 16 until the first end 22 locates in the recess 52 of the rim element 10 and the upper edge 26 of the side wall 16 contacts the first face 46 of the flange 42. In this position the skirt 50 extends down over an outer surface 15 of the side wall 16.

Once the collar 30 is fully engaged with the side wall 16, the engagement feature 58 that projects from the outer surface 34 of the collar 30 presses into and locally deforms an inner surface 17 of the side wall 16, thereby retaining the collar 30 within the side wall 16. In preferred embodiments in which the engagement feature 58 is in the form of a male screw thread, the engagement feature 58 forms a complementary helical impression or groove 80 in the side wall 16.

In this embodiment, with the rim element 10 fully engaged over the container side wall 16, the securing member 68 extends upwardly from the side wall 16 and forms an edge of the opening 76 of the container 12. The securing member 68 is shaped to engage with the lid 78 and seal the opening 76 of the container 12. Importantly, the rim element 10 and the lid 78 are designed so that the lid 78 may be repeatedly engaged with and removed from the rim element 10 without detaching the rim element 10 from the side wall 16 of the container 12.

When a user wishes to dispose of the container 12, the rim element 10 is separable from the main body 14, so that these may be disposed of or recycled separately. This is particularly advantageous when the rim element is made of a polymeric material and the main body is made of a cardboard material.

As described above, after insertion of the rim element 10 into the main body 14, the engagement feature 58 forms a correspondingly shaped groove or indent 80 in the side wall 16 of the container 12. In preferred embodiments the engagement feature 58 is a helical male screw thread and the indent 80 in the side wall 16 provides a complementary female screw thread. The rim element 10 may, therefore, be separated from the main body 14 by applying a turning force to the rim element 10 to unscrew the rim element 10 from the main body 14.

In order to form the groove or recess in the side wall, the projection of the engagement feature is preferably tapered such that the upper and lower engagement surfaces converge towards a radially outer apex or ridge of the projection. This allows the projection to more easily dig into or deform the inner surface of the side wall. A part of a further embodiment of a container 112 is shown in Figure 4. In this embodiment a rim element 110 is attached to a lining 182 that extends over at least a part of an inner surface 117 of a main body 114 of the container 112. The lining is typically flexible and non-self-supporting.

The rim element 110 is substantially the same as the rim element of the first embodiment and like features have been indicated by reference numerals incremented by 100.

The lining 182 is made of a flexible polymeric material and is sized and shaped so as to extend over and cover at least the inner surface 117 of the side wall 116 of the container 112. In this embodiment the lining 182 is in the form of a pouch that conforms to the main body 114 of the container and covers the inner surfaces 117 of the side wall 116 and base. The lining 182, therefore, has a closed lower end (not shown) and an open upper end 186. The upper end 186 defines an opening of the lining 182 and a diameter of the opening is substantially equal to an outer diameter of a collar 130 of the rim element 110.

The upper end 186 of the lining 182 is secured to an attachment region 166 at the second end 138 of the collar 130. The lining 182 is attached to an outer surface 134 of the collar 130 between an engagement feature 158 and the second end 138 of the collar 130. The lining 182 may be secured to the rim element using any suitable methods for forming a seal between the lining 182 and the rim element 110. In preferred embodiments the lining 182 is welded to the rim element, typically by heat welding; however, in other embodiments the lining 182 may be adhered to the rim element 110 using a suitable adhesive. In other embodiments the lining may be attached to an inner surface of the rim element.

When the rim element 110 is secured to the main body 114 of the container 112, the lining 182 extends from the rim element 110 in a direction towards the base of the container 112. The lining 182 is preferably in contact with the inner surfaces 117 of the main body 114 and in some embodiments the lining 182 may be lightly adhered to the main body 114. If the lining 182 is adhered to the main body 114, the strength of the adhesion should be low such that the lining 182 can subsequently be detached or peeled away from the main body 114 so as to fully separate the lining 182 and the main body 114.

In this embodiment, as well as the embodiment shown in Figures 5 and 6, it can be seen that the rim element 110, 210 does not include a securing member 68 as in the first embodiment. The rim elements 110, 210 in these embodiments comprise a collar 130, 230, a flange 142, 242 and a skirt 150, 250. An opening 176, 276 of the container 112, 212 is defined by the first end 136, 236 of the collar 130, 230.

Referring now to the embodiment shown in Figures 5 and 6, a second surface 248 of the flange 242 provides a sealing surface. A sealing layer or cover 288 extends over the opening 276 of the container 212 and is attached to the sealing surface 248. The sealing layer 288 will typically be made of a sheet of polymeric material or a sheet or film of metal foil. The sealing layer 288 may be a composite comprising layers of polymeric material and/or metal foil.

The sealing layer 288 is welded or adhered to the sealing surface 248 fully around the opening 276 so that the sealing layer 288 completely covers and seals the opening 276. The sealing layer 288 will typically be welded or adhered fairly strongly to the sealing surface 248 to prevent the sealing layer 288 peeling off accidentally during transportation or storage. However, in use, a consumer may tear or peel off the sealing layer 288 to gain access to the interior volume of the container 212. The sealing layer 288 may be heat welded to the rim element 210 or may be adhered to the rim element 210 using a suitable adhesive.

The container 212 further comprises a lid 278. The lid 278 extends over and covers the opening 276 of the container 212 and engages with the rim element 210. In this embodiment the lid 278 extends over and covers the sealing layer 288 so as to protect the sealing layer 288 during transportation and storage of the container 212. During use, the lid 278 must be removed from the main body 214 of the container 212 in order to remove the sealing layer 288. However, the lid 278 may be replaced on the main body 214 after removal of the sealing layer 288 to allow the container 212 to be closed or covered if required. Importantly, the lid 278 and the rim element 210 are designed such that the lid 278 may be repeatedly engaged and disengaged from the rim element 210.

The lid 278 comprises a circumferential rim 290 including a side wall portion 292. An edge of the side wall portion 292 includes a retaining lip 294. When the lid 278 is secured to the rim element 210, the side wall portion 292 of the rim 290 extends around and over the skirt 250 of the rim element 210 and the retaining lip 294 locates under the free edge 256 of the skirt 250. Engagement of the retaining lip 294 with the skirt 250 of the rim element 210 retains the lid 278 on the main body 214 of the container 212. To remove the lid 278 from the container 212 a part of the side wall portion 292 is flexed outwardly to disengage the retaining lip 294 from the skirt 250 of the rim element 210.

In the preceding embodiments the containers comprised a side wall, a base and a rim element attached to an upper edge of the side wall furthest from the base. In other embodiments a container 312 may comprise a tubular side wall 316 having a first end 322 defining a first opening 328 and a second end 324 defining a second opening 396. A first rim element 310 may be attached to the side wall 316 at the first end 322 and a second rim element 311 may be attached to the side wall 316 at the second end 324, as illustrated in Figure 7.

One end 324 of the tubular container 316 may be configured as a base of the container 312. A base plate 398 is attached to the second rim element 311 so as to cover and seal the second opening 396. The base plate 398 may be bonded, welded or adhered to the rim element 311 using any suitable means. The base plate 398 may be secured to the rim element 311 before or after the rim element 311 is inserted into the end 324 of the tubular side wall 316. In some embodiments the base plate 398 may be integrally formed with collar 330, flange 342 and skirt 350 portions of the rim element 311. A lid (not shown in Figure 7) may be removeably attached to the first rim element 310.

Each of the first and second rim elements 310, 311 includes an engagement feature 358 extending radially outwardly from the outer surface 334 of the collar 330. The dimensions of the collar 330 and engagement feature 358 allows each rim element 310, 311 to be inserted into the respective end 322, 324 of the tubular side wall 316 by applying a force substantially parallel to a longitudinal axis 320 of the side wall 316. As described above in relation to the first embodiment, the engagement feature 358 preferably comprises a helical rib that digs into the inner surface 317 of the side wall 316 to create a corresponding helical groove 380. The rim elements 310, 311 may then be removed from the ends 322, 324 of the tubular side wall 316 by applying a twisting force so that the rim element 310,311 is effectively unscrewed from the side wall 316 by cooperation of the helical rib 360 and groove 380.

In all embodiments in which the engagement feature comprises a helical rib, it is preferable if the rib extends over the surface of the collar so that a first end of the rib contacts the first face of the flange. In this way, when the rim element is attached to the edge of the side wall, the rib presses into the inner surface of the side wall and forms a groove that extends fully to the edge of the side wall.

In the embodiments described above the engagement feature of the rim element forms a corresponding engagement groove in the side wall once the rim element has been located on the side wall by local deformation of the side wall. In other embodiments, however, the rim element may comprise a male engagement feature comprising a projection. A corresponding female engagement feature, comprising a groove or recess, may be preformed in the side wall. In these embodiments, during attachment of the rim element to side wall the collar and/or the side wall will elastically deform until the male engagement feature locates in the female engagement feature. For example, the male engagement feature may include a projection that locates in a corresponding recess in the side wall. Once the male engagement feature has located in the female engagement feature the rim element is fully attached to the side wall.

Figure 8 illustrates an engagement feature 458 of a rim element 410 comprising a helical rib 460 having a triangular cross-sectional shape. A lower engagement surface 462 of the rib 460 extends at an angle from an outer surface 434 of a collar 430 of the rim element 410. An upper engagement surface 464 extends substantially perpendicularly from the collar 430. A corresponding engagement groove 480 having a triangular cross-sectional shape is provided in an inner surface 417 of the side wall 416 of a container 412. As shown, with the rim element 410 fully attached to the side wall 416, the rib 460 locates in the groove 480 to retain the rim element 410 on the side wall 416.

In other embodiments the engagement feature may comprise one or more projections of any suitable dimensions. The projections may not extend around the full circumference of the collar. The projections are preferably shaped so as to dig into or locally deform the inner surface of the side wall so as to retain the rim element on the side wall. The projections are such, however, that the rim element can be removed or detached from the side wall by applying a force to the rim element that is not parallel to the axis of the rim element. This force may be a turning force applied such that the rim element rotates about the axis of the rim element, or the force may be a linear force applied to the rim element at an angle to the axis, i.e. non-parallel and non-perpendicular to the axis. The applied force may elastically deform the rim element during separation of the rim element and side wall. This deformation causes a male engagement feature on the rim element to disengage from a female engagement feature of the side wall.

The present invention, therefore, provides a container comprising a side wall made from a fibre- or pulp-based material such as paperboard and a rim element made from a suitable polymeric material. The rim element is removeably attached to an edge of the side wall so that when a user wishes to dispose of the container the rim element may be removed fully from the side wall. The container may further comprise a lining that is permanently attached to the rim element and/or a lid that is securable to the rim element to seal the container.

Claims

1. A rim element for a container, the rim element being a unitary element made of a polymeric material, and the rim element comprising: an annular collar having a radially inner surface and a radially outer surface, an external diameter of the collar being sized to be received within an opening of said container; an aperture defined by the inner surface of the collar; a flange extending radially outwardly from the outer surface at a first end of the collar; and an engagement feature comprising one or more projections extending from the outer surface, the engagement feature extending circumferentially around the collar.

2. A rim element as claimed in Claim 1, wherein the projection comprises an engagement surface facing generally away from the flange and extending at an angle to the outer surface of the collar.

3. A rim element as claimed in Claim 1 or Claim 2, wherein the projection has a tapered cross-sectional shape such that the projection extends outwardly to an apex or ridge of the projection.

4. A rim element as claimed in any preceding claim, wherein the projection comprises a helical rib.

5. A rim element as claimed in Claim 4, wherein a first end of the helical rib contacts the flange.

6. A rim element as claimed in any preceding claim, wherein the collar has a second end, opposite the first end, and wherein the projection does not extend to the second end, thereby defining a region of the collar between a second end of the projection and the second end of the collar.

7. A rim element as claimed in any preceding claim further comprising a skirt portion extending from the flange.

8. A rim element as claimed in Claim 7, wherein the skirt portion extends from a radially outer edge of the flange in a direction towards a second end of the collar.

9. A rim element as claimed in Claim 7 or Claim 8, wherein a recess defined between the skirt portion and the collar is configured and sized to receive an edge of a side wall of said container.

10. A rim element as claimed in any preceding claim further comprising a securing member configured for engagement with a lid of said container.

11. A rim element as claimed in Claim 10, wherein the securing member is annular and extends from the first end of the collar or from the flange.

12. A rim element as claimed in any preceding claim further comprising a base plate extending across the aperture.

13. A liner assembly for a container comprising: a rim element including an annular collar having a radially inner surface and a radially outer surface, an aperture defined by the inner surface of the collar, a flange extending radially outwardly from the outer surface at a first end of the collar, and an engagement feature comprising one or more projections extending from the outer surface, the engagement feature extending circumferentially around the collar; and a flexible lining including a tubular portion having an annular edge, the lining being attached to the collar of the rim element around the annular edge proximate a second end of the collar.

14. A liner assembly as claimed in Claim 13, wherein the lining is attached to the outer surface of the collar.

15. A liner assembly as claimed in Claim 13 or Claim 14, wherein the lining is made of a polymeric material.

16. A liner assembly as claimed in any one of Claims 13 to 15, wherein the lining is in the form of a pouch having a closed end.

17. A liner assembly as claimed in any one of Claims 13 to 16, wherein the lining is heat welded to the collar.

18. A container comprising: a tubular side wall made from paperboard or cardboard, the side wall including an annular edge at a first end of the side wall; and a rim element attached to the side wall, the rim element including an annular collar having a radially inner surface and a radially outer surface, an aperture defined by the inner surface, a flange extending radially outwardly from the outer surface at a first end of the collar, and an engagement feature comprising one or more projections extending from the outer surface, the engagement feature extending circumferentially around the collar, wherein the flange extends over the annular edge of the side wall and the collar extends away from the annular edge over a part of an inner surface of the side wall, and wherein the one or more projections extend into a part of the side wall to retain the rim element on the side wall.

19. A container as claimed in Claim 18, wherein the projection comprises a helical rib and a corresponding helical groove is formed in the side wall.

20. A container as claimed in Claim 18 or Claim 19, wherein the rim element further comprises a skirt portion extending from the flange, and wherein the skirt portion extends over an outer surface of the side wall.

21. A container as claimed in any one of Claims 18 to 20 further comprising a flexible lining including a tubular portion having an annular edge, the lining being attached to the collar of the rim element around the annular edge proximate a second end of the collar.

22. A container as claimed in Claim 21, wherein the lining conforms to the shape of the side wall.

23. A container as claimed in Claim 21 or Claim 22, wherein the lining is adhered to the side wall.

24. A container as claimed in any one of Claims 18 to 23 further comprising a base at a second end of the side wall.

25. A container as claimed in Claim 24 when dependent on any one of Claims 21 to 23, wherein the lining conforms to the internal shape of the side wall and base.

26. A container as claimed in any one of Claims 18 to 23, wherein the container comprises a first rim element attached to the first end of the side wall and a second rim element attached to a second end of the side wall.

27. A container as claimed in any one of Claims 18 to 26 further comprising a lid, and wherein the rim element comprises a securing member configured for engagement with the lid such that the lid may be repeated engaged with and detached from the rim element.

28. A method of assembling a container comprising: aligning an annular collar of a rim element with a first end of a tubular side wall, the side wall being made from paperboard or cardboard; applying a force to the rim element parallel to an axis of the tubular side wall to insert the collar such that the collar extends over a part of an inner surface of the side wall; and continuing to apply a force to the rim element until a flange of the rim element contacts an annular edge at the first end of the side wall, wherein, once the rim element is fully inserted an engagement feature comprising one or more projections extending from an outer surface of the collar press into an inner surface of the side wall to retain the rim element on the side wall, the engagement feature extending circumferentially around the collar.

29. A method as claimed in Claim 28, wherein the engagement feature comprises a helical rib projecting from the collar, and wherein the helical rib presses into the inner surface of the side wall so as to form a helical groove that extends to the annular edge of the side wall.

30. A method as claimed in Claim 28 or Claim 29, further comprising the step of bonding a flexible lining to the rim element before inserting the rim element in the end of the side wall.

31. A method of disassembling a container, the container comprising a rim element attached to a first end of an annular side wall, the rim element comprising a collar extending over an inner surface of the side wall and a flange in contact with an annular edge at the first end of the side wall, and the method comprising applying a force to the rim element to disengage an engagement feature projecting from an outer surface of a collar of the rim element from a complementary recess formed in an inner surface of the side wall, the direction of the force being nonparallel to an axis of the container.

32. A method as claimed in Claim 31, wherein the engagement feature comprises a helical rib projecting from the collar engaged in a complementary helical groove in the inner surface of the side wall, and the method comprises applying a rotational force to the rim element to unscrew the rim element from the side wall.

33. A rim element substantially as herein described with reference to or as shown in Figures 1 to 3.

34. A rim element substantially as herein described with reference to or as shown in Figures 4 to 7.

35. A liner assembly substantially as herein described with reference to or as shown in Figure 6.

36. A container substantially as herein described with reference to or as shown in Figure 1.

37. A container substantially as herein described with reference to or as shown in Figure 5.

38. A container substantially as herein described with reference to or as shown in Figure 7.