GB2423916A

GB2423916A - A close-fitting liner for a waste container.

Info

Publication number: GB2423916A
Application number: GB0604479A
Authority: GB
Inventors: Peter Lowe
Original assignee: Egbert H Taylor and Co Ltd
Current assignee: Egbert H Taylor and Co Ltd
Priority date: 2005-03-09
Filing date: 2006-03-06
Publication date: 2006-09-13
Anticipated expiration: 2026-03-06
Also published as: GB0504864D0; GB0604479D0; GB2423916B

Abstract

A close fitting liner of a waste container consists of an integral open-mouthed plastic moulding having sides and a base, the outside of the liner being in use adapted to be adjacent the interior of a waste container and spaced there from by an air volume. In preferred embodiments the air volume is wholly or partially of foamed material.

Description

Insulated Waste Container This invention relates to an insulated container

for waste, and particularly to a wheeled waste container in the size range 500-2500 litre.

Wheeled waste containers are very commonly used for accumulation of waste by businesses and the like. Smaller domestic containers are typically of plastic. Both metal and plastic containers are emptied by upending over the hopper of a refuse truck.

Medium sized waste containers, in the size range 1000-1300 litre, are often used for collection of recycling materials, such as glass. Such containers are relatively inexpensive since they are produced in quantity, and have special lids adapted to the materials to be recycled.

It has been proposed to use sound deadening mats or pads within refuse containers, to minimize the noise generated as a container is filled, but these are only partially effective. What is required is an inexpensive and effective solution which can be applied to an existing standard' container without difficulty.

According to one aspect of the invention there is provided a closefitting liner for a waste container and comprising an integral open mouthed plastic moulding having sides and a base, the outside of the liner being in use adapted to be adjacent the interior of a waste container, and to be spaced therefrom to define an air volume.

The air volume may be comprised of an air space, the air content of a foam material, or a combination of foam material and an air space. The air volume defines a insulating space adapted to attenuate noise passing therethrough.

Preferably such a liner provides one or more air gaps between the liner and the container in use, the gap(s) being effective at suppressing noise transmission whilst at the same time giving a minimal reduction in container volume. In one embodiment, the liner comprises a twin wall rotary moulding comprising an outer wall having a separation from an inner wall. The separation of the inner and outer walls may comprise a substantially continuous air gap.

The outer wall and inner wall may be bridged by relatively resilient material, such as foamed plastic. The bridging may be continuous or partial. The liner may comprise unloamed inner and outer skins, the volume between said skins being wholly or partially of foamed material. Preferably the foamed material is provided over substantially the whole surface of said skins.

In another embodiment the liner comprises a single wall moulding having relatively resilient material on the outside thereof, for example in the form of resilient pads.

The resilient pads are preferably of expanded foam, and in a preferred embodiment are in the form of strips. The number and position of such pads is selected to give effective spacing of the liner from the container whilst maximising the air gap volume therebetween.

Typically the liner is of HDPE (high density polyurethane), whereas resilient material is of expanded polyurethane foam.

According to a second aspect the invention comprises a waste container incorporating a liner above mentioned.

According to a third aspect, the invention provides a method of producing a close-fitting liner for a steel waste container comprising the steps of: mounting a corresponding container in a rotary moulding machine whilst providing a metal lid for the corresponding container; introducing a quantity of rotary moulding powder into the corresponding container; moulding a liner for the container in the corresponding container by rotary moulding; extracting the liner; and trimming the mouth thereof.

Such a method produces a closely fitting liner as a consequence of the inevitable material shrinkage during curing of the liner. Thus is created an air gap when the liner is placed within the intended container.

A liner of foamed and unfoamed material can be formed by successive release of moulding powder during a rotational moulding process.

By applying foam strips to the exterior of an unfoamed liner, an air gap is created as the liner is fitted into the container.

As an alternative the gap between liner and container can be filled with a foamed material, which provides cushioning and air insulation by virtue of the voids therein.

In the preferred embodiment the container is tapered outwardly from the base. Such an arrangement is useful for waste containers because it ensures complete emptying as the container is upended. Where the container is used as a mould, this taper allows the freshly moulded liner to be easily removed. Furthermore, after application of resilient pads, the liner is easily inserted, and can be arranged to become a close fit as the fully inserted condition is reached.

Other features of the invention will be apparent from the following description of a preferred embodiment shown by way of example only in the accompanying drawings in which:- Fig. 1 is a view of the carcass of a typical steel waste container.

Fig. 2 is a view of a liner for the carcass of Fig. 1; and Fig. 3 is a cross-section through the wall of an insulated container.

Fig.4 is a transverse section through a liner for an open mouthed waste container.

Fig.5 is an enlarged wall section of the liner illustrated in Fig.4.

Fig.6 is an alternative enlarged wall section.

Fig.7 is another alternative enlarged wall section.

Fig.8 is a transverse section through a rotational moulding head with metal waste container as mould.

Fig.9 is an enlarged wall section of a lined waste container.

With reference to the drawings, Fig. 1 shows schematically the open mouthed steel carcass 10 of a metal waste container which comprises walls 11 and a base 12. The walls are tapered inwardly towards the base to encourage waste to fall out when the container is upended.

Typically a carcass may have embossed ribs in the walls to improve stiffness thereof, and other features of shape intended to improve aesthetic appeal. A completed container includes a castor at each corner of the base, a lid hinged along one long edge of the mouth and a lifting bar for the refuse vehicle; for simplicity none of these features are illustrated.

Container carcasses are mass produced on jigs, and thus dimensionally very similar.

The lids are often formed by rotational moulding. It has been realised that a disadvantage of rotational moulding provides a benefit in connection with the invention.

A feature of rotational moulding is that the article shrinks on curing, typically by about 3%, though the effect is somewhat variable. This aspect is usually considered a considerable disadvantage, because the mould must be made oversize to allow for shrinkage, and may also be non-uniform because shrinkage is not even. Furthermore considerable skill and experience is required during the rotational moulding process to ensure distribution of powder and heat in a manner suitable for producing a dimensionally acceptable product.

In the present case however, the steel carcass can itself be used as a mould provided a metal lid is provided to enclose the powder. Thus a liner can be moulded to be a close fit, but with an air gap after shrinkage.

Fig. 2 shows such a liner 13, typically of I-IDPE and having a wall thickness of 1-2 mm.

Attached to the exterior wall of the liner, for example by adhesive, are strips 14 of expanded polyurethane foam, each 50-100 mm wide, and about 10 mm thick. Further strips are provided on the base, typically three but sufficient to space the liner from the base in use.

Fig. 3 illustrates a typical assembled cross-section showing the wall 11, liner 13 and foam strip 14. It will be appreciated that the draw angle to the vertical, illustrated by arrow 15, permits easy insertion of the finished liner so that the foam strips just bridge the gap on full insertion. For the same reason, the liner can be easily removed for replacement. Any conventional means can be employed for retaining the liner in the carcass.

The container of the invention is easily adapted from a conventional container, and can revert to a standard condition on removal of the liner. The method described herein is an inexpensive means of producing a liner, which is also suitable for temperature insulation, in addition to noise suppression.

An alternative embodiment is illustrated in Figs.4-7.

A drop in liner 21 of generally rectangular box-like form has a wall comprising an inner skin 22 and an outer skin 23. The gap 24 between the skins is a closed air space. A liner of this kind can be formed by rotational moulding whereby a moulding powder is placed in the space between male and female mould parts, and the mould is rotated under heat to distribute the mould powder over the inner surface of the mould where it fuses to form a hollow wall. By careful control of rotation, the relative skin thickness can be controlled to some extent.

A liner with air gap is particularly effective as noise insulation when placed in a steel waste container.

Various configurations of wall are possible.

Fig.5 illustrates a simple double skin construction having the inner wall 25 and outer wall 26 formed of a suitable rotational moulding powder, for example HDPE.

Fig.6 illustrates an alternative two stage moulding process in which thin outer and inner skins 27,28 are moulded in a first stage. In a second stage an alternative moulding material is released into the mould, and comprises a suitable moulding powder with a blowing or foaming agent. By suitable control of powder quantity inner foamed layers 29,30 can be formed whilst leaving an air gap 31. The air gap may be less regular than illustrated. If desired the air gap can be eliminated by use of a suitable quantity of foaming powder.

In the embodiment of Fig.7, only foamed layers 32,33 are provided, each layer comprising closed cells and having a very thin skin. Such a construction may be suitable for some kinds of container contents, or may be complemented by a single thickness liner inserted within to provide impact resistance.

It will be understood that the moulding process can be controlled to provide a thicker base than sides (for impact resistance), and to vary the thickness of the air gap.

Typically, overall wall thickness is of the order of 30mm. In the embodiment of Fig.6, the outer and inner skins 27,28 may be about 1-2mm thick, whereas the foamed layers 29,30 may be 8-10mm thick. The overall thickness of the base may be greater than the sides, for example 50mm.

A process for forming an insulated liner in a metal waste container is illustrated in Figs. 8 and 9.

The pivoting head 40 of a rotational moulding machine has releasably clamped thereto the metal carcass of a waste container 41. Representative swing-away clamps 42 are illustrated. The container 41 acts as its own mould so that moulding powder introduced from the head 40 is distributed over the interior of the container to form an integral liner. Any material which bridges the mouth of the container can be trimmed after release from the mould.

This technique is particularly suitable for forming a liner having a single foamed layer, or a successive foamed layer 42 and solid layer 43 as illustrated in Fig.9.

Claims

Claims 1. A close-fitting liner for a waste container and comprising an

integral open mouthed plastic moulding having sides and a base, the outside of the liner being in use adapted to be adjacent the interior of a waste container, and to be spaced therefrom to define an air volume.
2. A liner according to claim 1, wherein said air volume includes the air content of a foamed material.
3. A liner according to claim 2, wherein said air volume comprises solely the air content of a foamed material.
4. A liner according to any preceding claim and comprising a twin wall rotary moulding comprising an outer wall having a separation from an inner wall.
5. A liner according to claim 4 and comprising unfoamed inner and outer skins, the facing surfaces of said skins being substantially of foamed material.
6. A liner according to any of claims 1-3 wherein said liner comprises a single wall moulding having relatively resilient material on the outside thereof in the form of resilient pads.
7. A liner according to claim 6, wherein said pads are in the form of strips.
8. A liner according to claim 7, wherein said strips are arranged vertically in use.
9. A waste container having internally a liner according to any preceding claim.
10. A method of producing a close-fitting liner for a steel waste container comprising the steps of: mounting a corresponding container in a rotary moulding machine whilst providing a metal lid for the corresponding container; introducing a quantity of rotary moulding powder into the corresponding container; moulding a liner for the container in the corresponding container by rotary moulding; extracting the liner; and trimming the mouth thereof.