GB2175282A

GB2175282A - Stackable containers

Info

Publication number: GB2175282A
Application number: GB08510397A
Authority: GB
Inventors: Steve Kelsey
Original assignee: Crown Decorative Products Ltd
Current assignee: Akzo Nobel Decorative Coatings Ltd
Priority date: 1985-04-24
Filing date: 1985-04-24
Publication date: 1986-11-26
Also published as: GB2175282B; GB8510397D0

Abstract

A container e.g. for paint 20 comprises a tray (10) and a lid (11). The tray has a flange (13) terminating at a lid-engaging wall (14). Vertical ribbing (15) extends from the flange to the base of the tray and the flange offers an internal heat sealing surface (16) to which is sealed a membrane (17) extending over the contents of the container. The lid has a depression (18) in close proximity with the membrane. Vertical ribs (28) are integral with parts of the lid and the lid has location means (27) to align vertically stacked trays. Vertical stacking loads are taken through the ribs on lid and tray. The dimensions of the lid relative to the vertical ribbing (15) are such that trays can be stably stacked with a slight tilt in a horizontal direction. <IMAGE>

Description

SPECIFICATION Stackable containers This invention relates to stackable containers.

The invention is concerned with the problems of making, stacking, transporting and displaying of compositions having a pseudoplastic or thixotropic structure, such as certain paints, in trays or shallow pans.

The broad concept of having false bodied coating compositions in a shallow pan or container is disclosed for exampie in GB 2 142 305A. Prudently, consideration must be given to the stacking of the containers as may arise immediately after filling; during storage prior to transport; during transport; and during display.

In accordance with the present invention a stackable container comprising a tray and a replaceable lid is characterised in that: (a) the tray has nominally vertical walls with an upper-most outwardly extending flange terminating at an upstanding lid-engaging wall; (b) the wall of the tray has vertical ribbing extending from immediately below the flange to the base of the wall, which ribbing reaches outwardly from the wall by an amount to provide support for the tray when on edge; (c) the flange offers on its upper face a heat sealing surface; (d) a membrane extends over the top of the tray and is heat sealed at the heat sealing surface; (e) the lid has a depression which is in close proximity with the membrane; (f) around the depression in the lid and extending towards the rim of the lid, vertical ribs are provided; and (g) location means are provided on the lid whereby the bottom of the wall of an upper tray in a stack can accurately engage with the location means on the lid of a lower tray to vertically align the trays to allow vertical stacking loads to be taken through the ribs in the lid and on the tray.

Preferably, the lid has a downward extending peripheral web which shares the vertical stacking loads with the ribs in the lid.

The advantages arising from the invention are: (1) A substantial stack (e.g. twenty trays each weighing typically about four Kgs when filled) of horizontally orientated trays can be stably built up.

(2) The vertical edges of the ribs on the tray give stability for vertical or near vertical (on edge) orientation of the trays.

(3) A filled tray having a horizontal orientation can be moved to a vertical orientation and any tendency for the contents of the tray to sag to form a paunch is resisted by the membrane and seal backed up by the depression in the lid.

(4) The vertical upstand on the flange together with the flange provide added containment for the contents of the tray when in use with the lid removed.

One form of the invention will now be described with reference to the accompanying drawing in which Figure 1 is a sectional elevation of one wall and lid of a rectangular tray and Figure 2 is a dia grammatic plan view of the tray and lid (to a re duced scale) with the Figure 1 section marked by the line l-l.

The stackable container of the drawings com prises a tray 10 and a replaceable lid 11. The tray has nominally vertical (1 outward tilt) walls 12 with an uppermost outwardly extending flange 13 terminating at an upstanding lid-engaging wall 14.

The tray has a filling 20 of a pseudoplastic or thixotropic paint.

The wall of the tray has vertical web-like ribbing 15 (shown with dash line hatching for emphasis although not truly in the section) extending from immediately below the flange 13 to the base of the walls. The ribbing reaches outwardly from the wall by an amount (dimension 'x') to provide support for the tray and lid when on edge (i.e. the nominally vertical orientation). The flange offers on its upper face a heat sealing surface 16. A membrane 17 extends over the top of the tray and is heat sealed at the surface 16. The membrane can be a thin coated board, film or foil.

The lid 11 has a depression 18 which fits into the tray so as to be in close (say 0.5 mm) proximity with the membrane 17. Between the membrane and the upper surface 21 of the paint filling 20 there is provided a thin perforated sheet 22 which is a close fit in the tray and which can follow the fall of the surface 21 as the paint is consumed by passage through holes 23 in the sheet 22.

The sheet 22 has a lower integral peripheral rib 24 which eventually arrives in a complementary recess 25 in the base of the tray when the paint filling has been consumed. The sheet 22 also has a low (1.5 mm) upper rib 24A. Longitudinal ribs below the sheet 22 can also be provided according to the flexibility requirements of the sheet 22 (reference is made to European Patent Application No.

84 308 525.9 for alternative constrictions of the sheet 22 and its functions).

The recess 25 serves the purpose of defining part of another recess 26, with the wall 12 of the tray, and this used (see top of Figure 1) to accept an upstand 27 moulded to the upper surface of the lid 11. The rib 27 need not extend all round the lid (see Figure 2). It is preferred to have the rib only at the four corners of the lid. Upstands 27, bases of the walls 12, and depressions 26 provide locating means to locate the tray above accurately in relation to the tray below when the trays are stacked in a vertical stack with a horizontal orientation of the trays.

The lid 11 has vertical web-like ribbing 28 integral with a vertical web 29 (which is continuous round the lid) and with an inclined part 30 of the lid. Both the ribbing 28 and web 29 contact the membrane 17.

It will be seen that the vertical load from the upper tray is taken first on the lid 11, then on the ribbing 28 and web 29 contacting the membrane 17, then on the flange 13 of the tray 10, then on the ribbing 15, and finally to the ground 31. Thus vertical loading, arising from stacking the filled trays whilst having a horizontal orientation, takes place on a continuum of vertical, thin, firmly supported ribs and web. The contents of the trays do not become loaded and neither is instability created in a stacking of trays if the paint contents of the trays do not offer a flat horizontal surface.

Typical dimension of a tray and lid are 300 mm x 270 mm x 60 mm. The lidded trays can also be stacked in a horizontal direction with a near-vertical orientation, each tray having a slight tilt. They are stable both individually and as a stack. To illustrate the near-verticai orientation a dash-line 32 has been added to Figure 1 to represent the ground with this orientation.

Typically six ribs 15 are provided equally spaced on each long side of the tray and five ribs 15 on each short side. The ribs 28 can match the ribs 15 on a one-for-one basis or slightly less ribs 28 can be provided.

Figure 2 shows diagrammatically the lid 11, tray 10, ribs 28/15 and webs 29. Corner support ribs 33 are also shown but these do not function as ribs 28/15; they merely strengthen the corners of the flanges 13. The corner moulded upstands 27 are also shown.

Claims

1. A stackable container comprising a tray and a replaceable lid is characterised in that: (a) the tray has nominally vertical walls with an uppermost outwardly extending flange terminating at an upstanding lid-engaging wall; (b) the wall of the tray has vertical ribbing extending from immediately below the flange to the base of the wall, which ribbing reaches outwardly from the wall by an amount to provide support for the tray when on edge; (c) the flange offers on its upper face a heat sealing surface; (d) a membrane extends over the top of the tray and is heat sealed at the heat sealing surface; (e) the lid has a depression which is in close proximity with the membrane; (f) around the depression in the lid and extending towards the rim of the lid vertical ribs are provided; and (g) location means are provided on the lid whereby the bottom of the wall of an upper tray in a stack can accurately engage with the location means on the lid of a lower tray to vertically align the trays to allow vertical stacking loads to be taken through the ribs in the lid and on the tray.

2. A stackable container as claimed in claim 1 in which the lid has a downward-extending peripheral web (29) which shares the vertical stacking loads with the ribs in the lid.

3. A stackable container as claimed in claim 1 or 2 in which the vertical ribbing on the tray in conjunction with the edges of the lid allow the container to be stably set with a vertical orientation having a slight tilt.

4. A stackable container as claimed in any preceding claim in which there is provided a thin flexible perforated sheet (22) which can lower to the base of the tray as the contents of the tray are consumed and said sheet has underside strengthening ribs (24); the base of the tray having recesses (25) to accommodate said ribs (24), and the recesses (25) defining further recesses (26) which can accept an upstand (27) on the lid of a tray below.

5. A stackable container substantially as hereinbefore described with reference to the drawings.