GB2030112A - Sift-proof containers - Google Patents

Abstract

A sift-proof container comprises an outer casing of four panels 10,12,14,16 hinged together by fold lines 20,22,24,26 extending from the top to bottom of the container and a sheet of lining material 44 for forming an inner bag which is adhered to the inside of the said panels 10, etc. The lining material 44 is dimensioned and positioned so that a region or regions 46-56 of the lining material 44 extend or extends beyond flaps 28-34 at one side of the container, so that said region or regions 46-56 may be made to overlap and/or overlap with another region or regions of the end of the lining material sleeve 44 for the closuring of the end of the lining bag. <IMAGE>

Description

SPECIFICATION Sift-proof container This invention relates to packaging containers which are referred to in the art as "sift-proof" containers. Such containers comprise an outer casing, usually of cut and creased cardboard, and an inner bag, usually of paper such as grease-proof paper or plain bleachcraft paper, which holds the container contents and whose function is to prevent the unwanted sifting of the contents out of a container.

These sift-proof containers are well known and are in extensive use for the holding of a wide variety of products from custard powder to weed killer granules, the material of the lining bag being selected to suit the contents to be held. The lining bags of the containers which are in use at present are provided with a sealed block bottom, and any of a variety of top closuring arrangements. The top may be open and may be simply be folded over to close the bag. The top closuring is not normally as important as that of the bottom closure, because the containers are usually stored, transported and used in upright condition so that the sifting of the contents through the bag top is not such a serious problem.

The tops of the bag can however be sealed if desired.

Conventionally, sift-proof containers are produced automatically by one of two methods.

In the first method, the bags are produced first, then the outer casings are erected around the bags. In the second method, the filled bags are inserted into the separately erected outer casings. For high volume production, these methods are economical, but are unsuitable for lower production rates, because the methods are relatively complicated and involve considerable capital investment in plant machinery. Lower volume production is by and large carried out manually or only semi-automatically, but in nearly all low volume production cases the bags are inserted manually into the erected outer casings.

We believe that there is a considerable market for a sift-proof container which is erectable by much less expensive machinery to eliminate much of the manual sift-proof container erection at present carried out. Such machinery, although it may not operate at the same speed as the machinery currently used for the automatic high-speed erection of siftproof containers, involves much less capital investment and can reduce the labour intensity requirement for lower volume production, leading to economies in production. The present -invention seeks to provide a sift-proof container with the above objective in mind.

The present invention relates to a specific construction of sift-proof container, and when reference is made to a sift-proof container hereinafter, such a container as will now be described is intended. The container in question has an outer casing made up of four panels hingedly interconnected by crease lines extending from top to bottom of the container. The panels are preferably such as to give the container a rectangular cross-section with the longer side being not more than twice the length of the shorter side, although the principle of the invention can be applied when this ratio is not met, and the lower ends of the panels have flaps by which the bottom of the casing is composed. The casing is produced in lay-flat form.That is to say, it is produced from an appropriately cut and creased blank, which is folded about two of said creases to cause the outer edges of the blank to overlap and said edges are adhered to produce the lay-flat form.

In accordance with the present invention, a sheet of lining material to form the inner bag is adhered to the blank panels before it is folded as aforesaid, and when the blank is folded the lining material is also folded and its edges overlap and are secured together whereby there is formed an inner lining sleeve within the outer casing sleeve, the lining material being dimensioned and positioned so that a region or regions of the lining material extends beyond the said flaps at one side of the lay-flat form, so that said region or regions can be made to overlap or overlap with another region or other regions of the end of the lining material sleeve and to which the first named region or regions may be attached by adhesive or by heat sealing, where the lining material is of appropriate composition for such heat sealing.

The said overlapping is preferably achieved by the folding of the said flaps in the erection of the container, but may be achieved using appropriate equipment, by folding or tucking of the lining material, independently of the flaps.

With the composite sleeve in lay-flat condition, the lower side of the lining material sleeve preferably extends beyond the upper side of the lining material sleeve thereby defining an exposed region of the inner surface of the lining material sleeve to which glue may be applied, and the said upper side of the sleeve extends beyond the flaps of the panels of the outer casing defining the upper surface of the composite sleeve, defining an exposed region of the outer surface of the lining material sleeve to which glue may be applied and when glue is applied as aforesaid, in the erection of the container, when the flaps of the smaller panels are pushed inwards, the sides of the inner sleeves are tucked inwards also and the glued regions overlap when the flaps meet and also along lines up the centres of the flaps attached to the larger panels, thereby sealing the end of the inner sleeve at the bottom of the container. To close the container bottom, finally the flaps attached to the larger panels are folded over and glued.

By this arrangement, glue may be applied in a single pass to the two exposed regions as aforesaid. As the composite sleeve will be in lay-flat form, the application of glue in this manner is extremely simple and can be done by conventional machinery. Similarly, the erection of the bottom of the container basically involves the folding in of the flaps attached to the bottom ends of the panels, and sealing of the inner lining material at the bottom will take place automatically. The erection of the flaps can be carried out by conventional machinery currently used for closing the ends of the containers comprising only a cut and creased blank.

The upper end of the inner sleeve may be closed similarly to the bottom end, or may be closed by any of the conventional methods.

The upper end of the outer casing may be provided with a hinged flap when the top end of the inner lining sleeve is normally left unsealed and is closed by a folding action, the said hinged flap serving as a re-openable closure. It is quite usual for sift-proof containers to have the function of being openable and closable at will.

An embodiment of the present invention will now be described by way of example with reference to the accompanying drawings, wherein: Figure 1 shows the container when in the form in which the outer casing is a blank to which an inner lining material sheet has been applied; Figure 2 shows the lower end of the container when in the lay-flat form; Figure 3 shows the bottom end of the container, inverted, after the lay-flat form has been opened out but prior to the closing of the bottom; Figures 4A and 4B and 5A and 5B show how the flaps attached to the shorter panels of the casing are folded inwardly; Figure 6 shows the container bottom prior to the folding over of the flaps connected to the larger panels of the casing; Figure 7 shows the container bottom fully closed; and Figure 8 shows the erected container when upright and prior to closing of the top end.

Referring to the drawings, the container is constructed from a sheet material blank to which a sheet of lining material has been applied. The blank may suitably be of cut and creased cardboard, and the lining material may be for example bleach craft paper. In Fig.

1 the blank is shown in full lines, whilst the lining material is shown in dotted lines. The blank comprises four hingedly interconnected panels 10, 12, 14 and 16 and to the free edge of panel 1 6 is provided a glue strip 1 8.

Panels 10, 12, 14 and 16 and inter-connected by hinge lines 20, 22 and 24 whilst strip 18 is connected to panel 16 by hinge line 26. These hinge lines 20 to 26 extend from top to bottom of the blank and flaps 28, 30, 32 and 34 are hingedly connected to the bottom edges of the panels 10 to 1 6 respectively. As seen clearly in Fig. 1, panels 30 and 32 are slightly longer than panels 28 and 34. At the top of each panels 10 and 14 is provided a tuck-in flap 36, 38 respectively, whilst the top end of panel 1 6 is provided with a hinge flap 40 provided with a tuck-in tab 42.

The lining material 44 is generally rectangular as shown except for a stepped portion 46 of which the edges 48 and 50 lie in alignment with hinges 20 and 24. It is to be noted that the step portion 46 extends beyond the ends of flaps 30 and 32 to provide a glue region 52 whilst the lining material at each side of the step 46 extends beyond panels 28 and 34 to provide further glue regions 54 and 56.

The hatched areas in Fig. 1 indicate the regions of gluing which attach the lining material 44 to the blank. Attention should be drawn to the re-shaped regions 58 and 60 connecting the lining material to the flaps 30 and 34. These V-shaped sections define a V angle of 90 .

In the first stage of erection of the container, the panel 1 6 is folded onto panels 1 2 and 14 about hinge line 24, glue having been applied to the underside of strip 18, and to the adjacent free edge of the lining material 44. Next, the panel 10 with a portion of lining material adhered thereto is folded over onto panel 1 2 about crease line 20. The portion of panel 10 which overlaps strip 1 8 becomes adhered thereto, and the edge of the lining material 44 which overlies panel 10 overlaps the previously glued free edge of the lining material so that in fact the construction becomes a composite lay-flat sleeve with the blank casing to the outside and the lining material to the inside. A portion of the lay-flat sleeve form is shown in Fig. 2, and it will be seen that the upper layer of the lining material sleeve profects beyond the ends of the two flaps 28 and 34 by virtue of the lining material extending as shown at 54 and 56 beyond these flaps. The regions 54 and 56 together define a region A as shown in Fig. 2 which is exposed and to which glue may be applied, and which lies to the outside of the sleeve, whilst the region 52 (also marked B in Fig. 2) as defined by the step 46 extends beyond region A. Glue is now applied to regions A and B simultaneously, and also the adjacent edge regions of flaps 28 and 34 as shown by the hatched area in Fig. 2. It is to be noted that region B to which glue is applied is in fact part of the inside surface of the lower layer of lining material.

When the container is erected from the layflat form to the form shown in Fig. 3, the glued regions A and B take up the positions shown. That is to say region A extends along the top edge of one of the larger sides, and along the top edge of one of the shorter sides, whilst region B extends along the top edge of the other larger side and the other shorter side.

In the commencement of the closuring of the bottom of the container, panel 28 is first of all folded inwardly as indicated by arrow 62 in Fig. 3 and the positions reached are as shown in Figs. 4A and 4B. The lining material adjacent the flaps 34 and 30 fold about 45 lines as shown so that in the case of the lining material adjacent flap 34, the glue region A on the folded part faces inwardly, whilst the glue region B on the folded part faces outwardly and becomes adhered to the inner face of the lining material. In the next stage of erection, the flap 32 is folded inwardly as indicated by arrow 64 in Fig. 5A, and similar folding of the lining material about diagonal lines takes place until the condition shown in Figs. 5A and 5B is reached.The folding of the lining material about diagonal lines is achieved by the V-shaped glue patterns 56 and 58 as shown in Fig. 1. As shown in Fig.

5A, the remaining portion of the glue region B is applied over the already folded portion of lining material and is applied to the upwardly facing portion of glue region A adjacent the flap 28, whilst the lining material edge portion facing inwardly at the opposite side of the remaining portion of the glue region A adjacent the edge of flap 34 is applied to the portion of glue region A shown in Fig. 4B, thereby to effect the sealing of the lining material up to the apex of the triangular portion of lining material shown in Fig. 5B.

Thereby, a complete sealing of lining material to lining material is effected, and the condition shown in Fig. 6 is reached. In the position shown in Fig. 6 there are still regions of the glue area A exposed, and to close the carton bottom, first of all flap 34 is folded as shown by arrow 66 in Fig. 6, and then flap 30 is folded over as indicated by arrow 68 in Fig. 6, until the finally closed condition shown in Fig. 7 is achieved. It is to be noted that spots of adhesive may be applied to the already folded over flaps 28 and 32, and to the outside of flap 34 after it has been folded over in the closing of the container bottom.

By the arrangement described there is achieved an inner lining bag of which the bottom is completely sealed, rendering it siftproof. In the example described, the upper end of the bag is left open as shown in Fig. 8, and to close such upper end, indicated by numeral 70, it is simply a matter of tucking in the smaller sides to bring the larger sides together, and folding over of the larger sides into the container casing. Thereafter, the flaps 36 and 38 are folded over and finally closure flap 40 is folded as indicated by arrow 72 in order to close the container in a re-openable manner.

Although we have described the use of adhesive for the connecting together of the extended regions of the lining material, if the material is of suitable composition, the container can be erected to the Fig. 7 condition without the use of adhesive, and then heat sealing arrangements may be applied across the bottom in order to seal the overlapping portions of lining material. In this connection the lining material would require to be of suitable material such as a coated paper or a synthetic resinous film.

It is of importance that the width of the larger sides should be more than the width of the smaller sides of the container in order to achieve overlapping of the folded over portions of lining material as illustrated in Figs.

5A and 5B.

Claims (7)

1. A sift-proof container comprising an outer casing of four panels hingeably connected by crease lines extending from top to bottom of the container, the lower ends of the panels having flaps by which the bottom of the casing is closed, said casing being of layflat form, a sheet of lining material for forming an inner bag adhered to the blank panels before the blank is folded to lay-flat form and when the blank is folded the lining material is also folded and its edges overlap and are secured together whereby there is formed an inner lining sleeve within an outer casing sleeve, lining material being dimensioned and positioned so that a region or regions of the lining material extends or extend beyond the said flaps at one side of the lay-flat form, so that said region or regions can be made to overlap and/or overlap with another region or regions of the end of the lining material sleeve to which the first named region or regions may be attached by adhesive or by heat sealing where the lining material is of appropriate composition heat sealing when the lining material is folded to form a lining material bag inside the casing.

2. A container according to claim 1, wherein the overlapping is achieved by the folding of the said flaps in the erection of the container, said flaps being such that the folding maybe effected using appropriate folding and tucking equipment.

3. A container according to claim 1 or 2, wherein in the lay-flat condition, the lower side of the lining material sleeve extends beyond the upper side of the lining material sleeve thereby defining an exposed region of the inner surface of the lining material sleeve to which glue may be applied to form the medium for achieving the communication between overlapping regions and the lining material.

4. A container according to claim 3 wherein, the upper side of the sleeve extends beyond the flaps of the containers of the outer casing defining the upper surfaces of the composite sleeve thereby to define an exposed region of the outer surface of the lining material sleeve to which glue may be applied, so that when glue is so applied in the erection of the container, when of the container, when the flaps of the smaller panels are pushed inwards the sides of the inner sleeves are tucked inwards also, and the glued regions overlap where the flap edges are adjacent and also along lines up the centres of the flaps attached to other panels thereby sealing the end of the inner sleeve of lining material at the bottom of the container, flaps attached to the larger panels being adapted to fold over and glued to the previously folded flaps.

5. A container according to claim 3 or 4 wherein both ends of the container are adapted to be closed in similar fashion by bag of identical construction.

6. A container according to any preceding claim wherein, the panels of the outer casing are such to give the container a rectangular cross-section with a longer side not being twice the length of the shorter side.

7. A sift-proof container substantially as hereinbefore described with reference to the accompanying drawings.