GB2546772A

GB2546772A - Blank for a carton, and carton formed therefrom

Info

Publication number: GB2546772A
Application number: GB1601582.8A
Authority: GB
Inventors: Adam Kearns Jamie
Original assignee: Keco Ltd
Current assignee: Keco Ltd
Priority date: 2016-01-28
Filing date: 2016-01-28
Publication date: 2017-08-02
Also published as: GB201601582D0

Abstract

A collapsible popup carton formed from a blank has two triangular panels 8a, 8b, one being folded G; two rectangular panels 4, 6 overlying each other; and two flaps 25, 26 secured to each other, with one secured to one of the triangular panels. A blank for forming it has two perpendicular straight edges; two triangular panels 8a, 8b; and two trapezoidal flaps 25, 26 whose parallel sides are parallel to each other to assist alignment in folding machines, one joined by a fold B to one of the triangular panels. All fold lines are preferably creases rather than cuts or score lines. The entire blank can be laminated with waterproof transparent film. Ideally the flaps only partially overlap and adhere where they do. A flap can include a fold line F partitioning it into a larger 25 and smaller 27 section so that the larger section can be glued to the triangular panel 8b and the smaller section can be glued to the other flap 26.

Description

Blank for a Carton, and Carton formed therefrom Field of the Invention

The present invention relates, inter alia, to a novel blank for a carton, especially a sandwich carton; to a partially-assembled, flattened container formed from the blank, to a method of making the partially-assembled flattened container, and to a fully-assembled carton erected from the partially-assembled container.

Background of the Invention

It is well-known to produce flat blanks, which can be partially assembled by folding and gluing, to make a partially assembled carton, which can be stored in a substantially flattened form. The partially assembled carton may then be erected to create a food-receiving compartment, and a foodstuff (typically a triangular-shaped sandwich) is inserted into the food-receiving compartment. A lid (which is preferably an integral part of the carton) may then be attached over the food-receiving compartment to create a sealed carton, with the foodstuff inside. The erected carton is typically of a substantially triangular prism shape, so as to snugly accommodate a corresponding triangular shape sandwich. Examples of such blanks, and the corresponding partially-assembled or fully-erected blanks, are disclosed in, inter alia, EP1919783 and GB248I681.

The blank is conventionally made from a foldable substrate such as card or paperboard, which is well-known to those skilled in the art.

In an effort to increase the shelf-life of the foodstuff, especially a sandwich, placed within the carton, it has further become conventional to use a substrate which is entirely coated on one or both surfaces with a relatively thin laminate film of a substantially water-impermeable film. Such film may comprise an oil-based synthetic plastics material such as bioxially orientated polypropylene (BOPP), but biodegradable laminate films are preferable, such as polylactic acid (PLA) or poly lactide. Suitable laminate-coated card or paperboard substrates are readily available commercially.

Such laminate film coating prevents the foodstuff from becoming dehydrated during transit and/or storage and so increases its shelf-life. If the substrate is laminated on only one surface, it is usual for this surface to form the inner surface of the carton in its fully erected and assembled condition. Among other reasons, leaving uncoated the side of the substrate which forms the outer surface of the carton facilitates printing of conventional images and text to be displayed on the packaging.

Conventionally, the food-receiving compartment is flanked on three edges by out-turned ‘flange’ portions and, on a fourth edge, by a hinged lid. Once the sandwich has been positioned in the food-receiving compartment of the carton, the fid is folded over and sealed to the out-turned flange portions. Advantageously this is effected by heat-sealing and desirably therefore the aforementioned laminate film on the inner surface of the carton is one which is heat-sealable.

In order to form a blank from the card or paperboard substrate (whether or not coated with a laminate film), a plurality of fold fines or scores are introduced. This is achieved in an automated process by passing the substrate along a machine provided with a cutting die which introduces a “pinch cut” or “kiss cut” into the substrate, that is, a cut through only part of the depth of the substrate. This weakens the substrate sufficiently to allow the substrate to be folded along the fine of the kiss cut in a subsequent processing step.

Once all the desired kiss cuts have been introduced into the substrate, the blanks are cut out from the substrate (by cutting through the entire depth thereof), and the cut, unfolded, blanks are typically then fed into the hopper or other feed mechanism of an automated folding or forming machine, which folds the blanks along the desired fold lines, to make a partially-assembled flattened container.

Typically the blank is maintained in the partially-assembled flattened condition by application of a glue, which may be either a “hot melt” adhesive or a cold glue. Conveniently the gluing steps are performed, in an integrated process, on the folding or forming machine. Thereafter, the partially-assembled flattened container can be erected into a fully assembled carton as and when required, typically by a simple “pop-up” action.

Although superficially trivial the design of commercially successful cartons, and blanks for forming them, is actually very difficult, since there are several competing parameters and it is not straightforward to achieve an effective compromise. Factors which must be accommodated or borne in mind in the design include: attempting to minimise the amount of material required (so as to increase efficiency); producing a blank which can be folded easily and accurately to produce a consistent quality carton; producing a carton which has the necessary structural rigidity, and also a high degree of integrity so as to increase the shelf-life of the packaged foodstuff. The applicant has found that existing blanks and cartons are not ideal and can be improved upon.

In particular, the applicant has observed the following deficiencies in prior art cartons/blanks of the sort disclosed in, inter alia, GB 2481681: a) Delamination — that is, the partial peeling away of the outer portion of the substrate from the underlying portion. This is thought to be due to the ingress of moisture into the substrate, especially at the fold lines of the carton. This is exacerbated by the cold temperatures at which the packaging of foodstuffs is typically performed, leading to condensation of atmospheric moisture on the packaging. Delamination is undesirable as it is unsightly and can be detrimental to the integrity of the packaging, facilitating the flow of air into the interior of the carton. b) Mis-folding of the blank - typical conventional blank designs for sandwich cartons may be prone to a number of mis-folding faults during folding of the blank, either during formation of the partially-assembled, flattened container, or subsequently during the erection of the fully assembled carton. These can result in a certain percentage of a production run of blanks being unfit for purpose since badly mis-folded blanks lead to cartons which are not properly sealed. An example of the type of mis-folding that can occur affects those blanks/cartons in which a side wall of the carton is formed from two separate wall portions which partially overlap, the overlapping region being glued or otherwise fixed to hold the separate wall portions together. The applicant has observed that there is a tendency for the wall portions to overlap inaccurately (i.e. more or less than is desired, and/or out of a desired alignment). This in turn means that a small part of the associated side wall ‘flange’ does not seal to the lid, allowing a small gap for air to enter the carton even after it has been supposedly sealed by the lid.

Another example of mis-folding that the applicant has observed in current conventional sandwich cartons is the “flange” along the top or bottom edge of the carton not being aligned with the lid - this can lead to part of the flange portion protruding beyond the edge of the lid, which is unsightly and can deter a prospective consumer.

Yet another example relates to the erection of a fully-assembled carton from a partially-assembled flattened container. In some prior art designs, in erecting the carton a panel is folded over about a hinge or fold line, but the components of the container are secured only on one side of the fold line, meaning that, as the panel is folded over, there is a tendency for the fold line or hinge to move slightly with the panel, so that the panel is not folded exactly along the intended fold line, leading to a misalignment in the erected carton. This problem arises because of what may be described as the “floating” nature of the hinge or fold line.

The current invention aims to ameliorate or prevent some or all of the problems associated with current conventional blanks and cartons.

Summary of the Invention

In a first aspect the invention provides a flat blank, having fold lines formed therein, adapted and configured for assembly of the blank into a substantially triangular prism-shaped carton for a sandwich, the blank being formed of a foldable substrate and comprising: a) at least a first straight edge and at least a second straight edge which are substantially perpendicular to each other and which facilitate the accurate feeding of the blank into an automated folding and gluing apparatus for folding and gluing the blank, one of the said edges being substantially parallel to the direction of motion of the blank as it is fed into the automated gluing apparatus; b) two panels which each form a respective entire triangular side wall in the assembled carton, and wherein each of which is formed from a respective single continuous piece of substrate material; and c) two substantially trapezoidal flaps one of which adjoins, via a fold line, one of the aforementioned panels which forms a triangular side wall in the assembled carton, and wherein the substantially parallel sides of one of said substantially trapezoidal flaps are substantially parallel to the parallel sides of the other of said flaps.

The substantially trapezoidal flaps, and their preferred features, are described in greater detail below.

Preferably substantially all of the fold lines in the blank are formed by creases rather than comprising a score, cut or kiss cut. By way of explanation, a cut is a cut through the entire depth of the substrate, whilst a score or kiss cut is a cut partially through the depth of the substrate, made using a knife edge cutting die, which weakens the substrate sufficiently to allow it to be folded. In contrast a crease is formed in the substrate by passing the substrate between a blunt, protruding male portion and a recessed female portion, with the application of pressure, which weakens the substrate without cutting partially through it. The applicant has found that substantially eliminating scores, cuts or kiss cuts in the blank increases the strength and integrity of the resulting carton and, in particular, reduces the percentage of blanks which are not fit for purpose. Again, by way of explanation, typical substrate used in blank manufacture is of the order of 290-400 pm in thickness. A cutting die used to produce a score or kiss cut in the substrate will slowly wear down with use, meaning that the pressure applied to the cutting die to achieve the desired depth of cut has to be increased. This is very difficult to perform accurately, and it is therefore difficult to achieve a consistent depth of cut in the substrate. In contrast, the blunt, rounded former used to introduce creases wears down at a much slower rate, so the crease formation is more consistent.

By substantially eliminating cuts, scores or kiss cuts from the blank, the structural rigidity and integrity of the resulting carton erected from the blank is improved, as noted above. In consequence, it can be possible to attain a similar degree of integrity of the carton as is achieved with conventional designs, but the present invention permits the use of thinner card or paperboard substrate, thus reducing the mass of substrate required to make the packaging.

The person skilled in the art will appreciate that it is not absolutely necessary to entirely avoid the presence of cuts, scores or kiss cuts in the blank or carton of the invention if the fold so produced is entirely overlaid by at least one layer of substrate in the erected carton (i.e. in the erected carton there is at least one layer of overlying substrate between the score or kiss cut and the external environment). As an example, referring briefly to Figure 1 of the drawings, described in greater detail below, it is found that fold line ‘F’ can include one or more scores or kiss cuts, or even one or more discontinuous cuts through the entire depth of the substrate, without significant detrimental impact on the integrity of the resulting carton.

Accordingly, for the purposes of the present invention, a blank and/or a flattened container is considered to have “substantially all” of its folds formed by creases, if no more than one fold comprises a cut (partial or complete) or score.

The design of the blank, the position and arrangement of fold lines, flaps and gluing, and (preferably) the substantial absence cuts, of kiss cuts or scores in the substrate of the blank, allow for the formation of a partially-assembled flattened container which can be consistently and accurately folded and glued on conventional automated forming and gluing machines, and which has substantially equal or better structural integrity relative to conventional blanks or partially-assembled containers. The invention in turn thus provides for consistently and accurately folded, glued and erected cartons, with a lower percentage of cartons having, for example, mis-aligned flaps or panels and thus less wastage of cartons being rejected as inadequate by quality assurance or quality control procedures.

The blank preferably has an aperture in the substrate, which aperture is preferably covered by a window of moisture-impermeable transparent film.

In a second aspect, the invention provides a partially-assembled, flattened container which can be erected into a fully-assembled carton by a “pop-up” action, the container preferably being made from a blank in accordance with the first aspect of the invention defined above, the partially-assembled flattened container being formed from a foldable substrate, optionally laminated on at least one side with a laminate film, and comprising two panels each of which is adapted and configured to form a respective triangular side wall, each panel forming an entire respective side wall from a single continuous piece of substrate, one of said panels being bisected by a fold line so that, in the partially-assembled flattened container one of the two halves of the bisected panel overlies the other half; two substantially rectangular panels, each of which is adapted and configured to form a respective end wall, wherein, in the partially-assembled container one of said substantially rectangular panels overlies the other; a first flap, at least part of which is secured to one of the aforementioned panels adapted and configured to form a triangular side wall; and a second flap, at least part of which is secured to at least part of the first flap.

Desirably the first flap is substantially trapezoidal. Desirably the second flap is substantially trapezoidal. In preferred embodiments both the first and second flaps are substantially trapezoidal.

More especially, in the partially assembled flattened container the first and second flaps are preferably arranged and glued such that the second flap overlies a part of the first flap, the overlapping parts of the second and first flaps being secured (e.g. conveniently, glued) to one another. Preferably, as noted above, both the first and second flaps are substantially trapezoidal and a straight edge of one of the flaps (preferably one of the edges of the nonparallel pair of sides) is a straight line and lies adjacent a fold line in the first trapezoidal flap, about which the flattened container is folded when it is erected into a fully assembled carton. Importantly, the securing (preferably gluing) is present on each side of the aforementioned fold line in the partially assembled flattened container: on one side of the fold line, the first flap is secured to the panel which forms one of the triangular side walls; and on the other side of the fold line, the overlapping portions of the first and second flaps are secured to one another.

By virtue of parts of the partially-assembled flattened container being secured either side of the fold line, the fold is substantially fixed in place translationally (i.e. the fold is still free to rotate about its axis and act as a hinge, but the axis of the fold is essentially fixed) as the container is erected, rather than being “floating” as in the prior art. This means that the erection of the carton is much more accurately achieved than with prior art arrangements and with substantially no mis-alignment.

In a preferred embodiment the visible portions of the first and second trapezoidal flaps in the partially-assembled flattened container are essentially congruent and are symmetrical about the “fixed” fold line. In an especially preferred embodiment the aforementioned visible portions of the first and second trapezoidal flaps resemble identical isosceles triangles with their respective apex truncated, leaving a V-shaped notch or cut out formed by the pair of flaps, the notch being bisected by the “fixed” fold line.

The “fixed” fold line may be formed by a crease and/or a partial cut or several discontinuous cuts in the blank (this being preferably the only fold line in the blank which is formed by a score, cut or kiss cut).

Another preferred feature of the blank of the invention relates to embodiments in which the blank comprises an aperture, but wherein the substrate is not entirely coated on one side with a laminate film. In such embodiments, it is desirable to cover at least the aperture with a patch of film, so that the packaged foodstuff is not open to the environment. It is conventional in such situations to apply a patch of laminate film window over the aperture, usually on that surface of the blank which will form the inside of the erected carton. The patch is conveniently secured by heat sealing, in an automated process performed on a “window patching” machine.

The patch is formed by cutting a suitably-sized piece of film from a supply of such film, the supply usually being in the form of a reel. In order to facilitate application of the patch it is desirable that the window aperture to be patched is oriented in the direction of travel of the blank through the window patching machine. In order to achieve this it is desirable to provide at least one straight edge on the blank which can engage with the feed mechanism of the window patching machine, so that the blank can be fed accurately, in the desired orientation, into the machine.

By way of explanation, the feed mechanism usually comprises two or more “feed knives”, which are typically metallic, projecting downwards towards a blank advancement means, such as a roller or belt. The feed knives are positioned to leave a narrow gap or gate between the lowermost part of the knives and the blank advancement means, such that only one blank at a time can advance through the gate into the window patching machine. In this way, a stack of flat blanks can be fed individually into the patching machine. As well as enforcing individual feeding of the blanks, the feed knives ensure that the blanks pass into the machine in a straight, linear fashion, the stack of blanks being urged against the feed knives (e.g. by a spring or the like), and the knives are positioned so that one or more straight edges of the blank engage with the front surface of the knives.

It will be appreciated that the straight edge of the blank must not be in line with the aperture in the direction of travel of the blank otherwise, as the blank advances, the feed knife will tend to pass through the aperture as the aperture passes beneath the feed knife and the blank will foul the feed gate. The straight edge used as the guide must therefore be offset laterally from the aperture in the blank.

The blank will also preferably comprise another straight edge, perpendicular to the straight edge described above. The second, perpendicular, straight edge can engage with a side feed guide means or “side gate”, which helps keep the blank correctly oriented through the feed mechanism. The second straight edge may conveniently be formed by an edge of the lid, the aperture typically being present in the lid.

The perpendicular pair of straight edges described above in relation to the feeding of the blank into a window patching machine are different to those described as feature (a) of the blank of the first aspect of the invention, which latter edges are desirable for linear feeding of the blank into a folding and gluing machine. Typically the respective pairs of straight edges are at an angle of 45° to one another.

In a third aspect, the invention provides a method of making a partially-assembled flattened container in accordance with the second aspect of the invention defined above, preferably using a flat blank in accordance with the first aspect of the invention defined above; the method comprising the steps of: (a) optionally, forming one or more pre-folds in the blank; (b) folding a first flap to overlie a panel which forms a triangular side wall, and securing at least part of the flap to the aforementioned panel; and (c) folding a second flap to overlie at least part of the first flap, and securing the second flap to that part of the first flap which it overlies. As noted above, preferably both the first and second flaps are preferably substantially trapezoidal.

It will be appreciated that step (c) is necessarily performed subsequently to step (b). Step (a) however is optional. If step (a) is performed, it may be performed in a single step. If two or more pre-folds are introduced, this may be done simultaneously or in separate steps and, depending on the location of the pre-folds being introduced, at least one such pre-folding step may be performed after performing step (b).

By way of explanation, a pre-fold is a fold made in the blank which is not required to be used in the process of converting the flat blank into a partially assembled, flattened container, but is useful in and facilitates the erection of the flattened container into a fully assembled, erected carton. To make a pre-fold, part of the blank is folded and then returned to its original position.

As noted elsewhere, the step of securing is conveniently achieved by applying adhesive to one or both parts of the blank to be secured together such that when the respective parts are contacted, the adhesive secures the parts together. Suitable adhesives are well known to those skilled in the art.

Preferably the method comprises forming at least a first pre fold which defines an edge of a substantially rectangular wall panel. More preferably the method comprises forming two pre folds, which folds define opposed long edges of a substantially rectangular wall panel. Conveniently these two pre folds are introduced in separate steps at different stages of the process.

In a preferred embodiment, step (b) additionally comprises folding a further flap, about substantially the same fold line as that used to fold the first flap. The shape of the further flap is not especially critical, but a substantially square-shaped flap is convenient. The first flap and the further flap are preferably folded substantially simultaneously in the same operation. The further flap is desirably folded so as to overlie one of the substantially rectangular end wall panels, but is not secured thereto.

The person skilled in the art will appreciate that, if using adhesive to secure at least part of the first flap to a panel which forms a triangular side wall, it is necessary to apply the adhesive before folding the flap. The adhesive may be applied to the flap, or to the panel forming the triangular side wall, or both.

In a similar manner, it is necessary to apply adhesive (if adhesive is the selected method of securing) before folding the second flap in step (c). In a preferred embodiment, adhesive is applied to the second flap and also an adjacent, substantially rectangular end wall panel. This adhesive may be applied in advance even of the step of folding the first flap, such that all adhesive application steps take place substantially simultaneously if desired, although this is not essential.

The substantially rectangular end wall panel, adjacent to the second flap, is folded over in the same operation as the folding of the second flap, and the end wall panel comes to overlie the additional (typically substantially square-shaped) flap preferably folded over in step (b), and is glued thereto.

More especially, the folding in step (c) is achieved by folding the blank about a fold line which bisects one of the triangular side wall panels, such that the main body of the blank (disregarding the lid) is essentially in two adjoined halves overlying each other, and glued in place. In this configuration the blank forms a partially-assembled flattened container, which can easily be erected by a “pop-up” action into an erected, fully assembled carton.

The “securing” is conveniently achieved by the application of a small amount of adhesive to one or both of the parts of the blank which are to be secured to each other, such that the parts are glued together.

Advantageously all of steps (a)-(c) are performed in an automated process using an automated folding and gluing machine. Such automated machines are well known to those skilled in the art.

Conventional folding/gluing machines have a feed mechanism similar to that described above in relation to the window patching machine. The feed mechanism typically comprises two or more feed knives which define a narrow gate, just wide enough to permit the passage there through of a single blank, such that a stack of flat blanks urged against the feed knives is fed in a succession of individual blanks into the folding/gluing machine. To facilitate accurate alignment of the blank in the feed mechanism, and thus subsequently in the folding/gluing machine, the blank comprises a pair of substantially perpendicular straight edges. One of the straight edges is at or near the front of the blank in its direction of travel through the machine and can be butted up against the feed knives. The other straight edge can be butted up against the “side gate” at the side of the feed mechanism.

In a preferred embodiment, the first (preferably substantially trapezoidal) flap comprises a fold line, which divides the flap into a major part and a minor part. In such an embodiment, it is preferred that the major part of the first trapezoidal flap is secured to the panel which is adapted and configured to form a triangular side wall, and the minor part of the first trapezoidal flap is not secured to the aforesaid panel, but is instead secured to part of the second (preferably substantially trapezoidal) flap.

In other aspects, the invention provides a method of erecting a fully-assembled erected carton from a partially-assembled flattened container in accordance with the second aspect of the invention and/or made by the method of the third aspect of the invention; and a fully-erected carton made from the partially-assembled flattened container.

Unless the context dictates otherwise, features which are preferable, advantageous, convenient etc. in relation to one aspect of the invention will generally apply equally to the other aspects of the invention.

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

Figure 1 shows one embodiment of a flat blank in accordance with the invention;

Figure 2 is a perspective view of the fully assembled carton made from the flat blank embodiment shown in Figure 1.

Figure 3 is a perspective view of the carton shown in Figure 2 but with the lid opened;

Figures 4-7 are a series of illustrations showing how the flat blank embodiment of Figure 1 is folded and glued to form a partially assembled, substantially flattened carton, which can be readily erected in a ‘pop up’ manner, as shown in Figure 3, to form an erected carton.

Detailed Description of an Embodiment

Referring to Figure 1, a flat blank 2 is provided. The blank comprises a foldable paperboard substrate, about 400 pm thick, optionally laminated with a thin film of substantially water-impermeable synthetic plastics material, such as polylactic acid or polylactide, which is heat-sealable. The Figure shows the side of the blank which forms the outer surface of the assembled carton. Conveniently the outer surface is not coated with any laminate film, so as to facilitate printing of text and/or images onto the exterior surface.

The blank comprises a plurality of fold lines, nearly all of which are formed in the blank by creasing rather than by kiss cuts. When folded, glued, and fully assembled, the blank can be made into the triangular prism-shaped sandwich carton shown in Figure 2.

The blank comprises a first substantially rectangular end wall 4, and a second substantially rectangular end wall 6 which, in the flat blank, is at an angle of about 90° to the first end wall 4. In fact the end walls 4 and 6 are slightly trapezoidal, and this is a preferred feature, so that the walls taper inwardly towards the bottom edge of the assembled blank, allowing nesting of the assembled blanks, which is important for ease of stacking/storage and for feeding into automated processing lines.

The blank also comprises a pair of substantially identical triangular side wall panels 8a, 8b. Side wall panel 8a is located between, and adjacent to, end wall panel 4 and end wall panel 6. The side wall panels 8a and 8b are both isosceles triangles. Side wall panel 8a is bisected by fold line G (the purpose of which is described below), such that side wall panel 8a is divided into two equal halves 8a’ and 8a”. The blank also comprises a hinged lid portion 12, which is generally rectangular in shape but with rounded comers. The lid portion 12 is hingedly connected to side wall panel 8b by creased fold line “A”. The lid portion 12 comprises an aperture 16, which is covered by a thin layer of transparent plastics film. This film-covered aperture allows a prospective purchaser to view the contents of the carton before purchase. The film may either be a small patch applied over the window (in the case of an unlaminated substrate), or may be film applied over the whole of the inner side of the blank (in the case of a laminated substrate).

One edge of each of end wall panel 4, side wall panel 8a, and end wall panel 6, is formed with a foldable flange portion 20, 20’ and 20” respectively. In addition, the blank comprises two substantially trapezoidal flaps. One of these, flap 22 adjoins, via a fold line “B”, the triangular side wall 8b. The flap 22 is provided with a fold line F, across a comer of the flap. The fold line F divides flap 22 into a major part 25 and a minor part 27. The other substantially trapezoidal flap is indicated by reference numeral 26.

Finally, the blank comprises a substantially square shaped flap 28. This is free (cut) on three of its four edges and is hingedly connected to the blank only along the fold line “C”.

The flat blank illustrated in Figure 1 is formed into a partially assembled, flattened container, in an automated process on an automated forming and gluing machine. Suitable machines for performing this process are commercially available from manufacturers such as Bobst or Jagenberg.

The first step in the process is to feed the blank into the automated forming and gluing machine. A stack of blanks is loaded into a hopper or other feeding arrangement, and the blanks fed individually (but at high speed) into the machine, typically by means of rollers and/or a belt. The blanks are able to be fed accurately into the machine by the interaction of feed knives in the feed mechanism of the machine with the straight edge of square flap 28 and flap 22, and by the interaction of the “side gate” of the machine with the outside edge of flange portion 20”, which edges are substantially perpendicular to one another. In particular the outside edge of flange portion 20” can engage or butt up against a feed guide or the like to ensure accurate orientation and positioning of the blank in the forming/gluing machine. The direction of feed into the automated forming/gluing machine is indicated by the arrow (32) in Figure 1.

Referring to Figures 4-6, the folding and gluing of the blank is performed on the folding/gluing machine largely as follows.

In a first step, a pre fold is formed along line “D”. Next, one or two dots of adhesive are applied to panel 8b (on the reverse side of that visible in Figure 1). The adhesive may be a hot melt adhesive or a cold glue, and may be applied to the blank in any convenient conventional manner. The method by which the adhesive is applied does not form any part of the present invention, but the preferred portions of the blank to which the adhesive is applied may, in some embodiments, contribute towards the invention.

In a third step square flap 28 and trapezoidal flap 22 are simultaneously folded inwards along creased fold line B, as illustrated in Figure 4.

The major part 25 of trapezoidal flap 22 is secured by adhesive to the triangular side wall 8b. The minor part 27 of trapezoidal flap 22 is however not glued to the side wall 8b but is free to fold along the diagonal fold line F, as indicated in Figure 5.

Fold line F is the one fold line in the blank which is not formed solely by creasing. The fold line comprises two short cuts through the entire depth of the substrate, separated by an intervening crease, and with a further crease at the opposed ends of the fold line. Accurate folding along fold line F is very important during the erection of the carton, and the use of the discontinuous cuts in this particular fold enhances the accuracy of the folding. The integrity of the resulting carton (in terms of resistance to flow of air into or out of the erected carton) is not significantly detrimentally affected by the cuts since the cuts are entirely overlaid, in the erected carton, by the side wall panel 8b, and at least partly, and supported by, trapezoidal flap 26 and major part 25 of trapezoidal flap 22.

In step four, a pre fold is formed along line “E”. In step five, adhesive is applied, in two stripes or spots, to panel 6 and panel 26.

In the next step, also as shown in Figure 5, half of the triangular side wall 8a (along with the attached end wall 6 and trapezoidal flap 26) is folded inwards by folding along the fold line G that bisects the side wall 8a, such that the half 8a’ comes to overlie the other half 8a” of the side wall panel 8a.

Further, a bottom portion of the end wall 6 comes to overlie the inward folded square flap 28, and is secured thereto by adhesive. Similarly, a part of trapezoidal flap 26 comes to overlie the minor part 27 of the trapezoidal flap 22, and the overlapping portions are secured by adhesive.

The resulting partially-assembled, flattened container is shown in Figure 6. The container can be stored and distributed in this form, and readily erected in a “pop up” fashion by pulling downwards and outwards on the end walls and/or by pushing inwards on the apex of the triangular side wall 8a, as indicated in Figure 7, thereby creating a food-receiving compartment which snugly accommodates 2 or 3 triangular cut sandwiches (the width of the end wall panels 4 and 6 can be adjusted to accommodate typically 2 or 3 sandwiches).

In opening out the partially assembled, flattened container into the erected carton, the edge of trapezoidal flap 26 is folded, along fold line F, so as to overlie the major part 25 of the trapezoidal flap 22 (the minor part 27 being obscured in Figures 6 and 7 by the trapezoidal flap 26).

An important feature of the design of the blank and of the partially assembled, flattened container is apparent in Figures 6 and 7. This is the V-shaped cut-out, indicated by reference numeral 50, formed at the end of fold line F, by the truncation of trapezoidal flap 22 (and, specifically, the major part 25 thereof) and the trapezoidal flap 26. By making these flaps trapezoidal, rather than triangular, fold line F can be terminated before reaching the fold line “A” of the lid portion 12, and the absence of substrate above the fold line facilitates folding of the substrate along the fold line F, in turn allowing accurate erection of the carton on an automated packaging line.

The erected cartons may be fed into the hopper or similar feed mechanism at the start of a packaging line. Because of the end walls 4, 6 being slightly trapezoidal (narrower at the bottom than the top) the erected cartons taper and can be nested in such a hopper. The erected cartons then pass along the packaging line in which sandwiches are inserted into the cartons (typically by hand). Once the sandwiches have been inserted into the cartons, the integral lid 12 is folded over and heat sealed to the flange portions 20, 20’ and 20”, this latter step being typically performed automatically by the packaging line apparatus.

The design of the blank and the manner of its folding and gluing into a partially-assembled, flattened container, confer certain advantages over prior art blanks and cartons of otherwise slightly similar design.

In preferred embodiments, the substantial avoidance of kiss cuts in the blank used to form the carton makes it less likely that moisture can penetrate the substrate, which in turn reduces the likelihood of delamination of the film used in laminated packaging.

The design of the blank allows for accurate and consistent folding in automated apparatus, thus reducing the likelihood of mis-folding and reducing the likelihood of a carton not being properly sealed. In particular, the presence of the V-shaped notch between the first and second trapezoidal flaps in the partially assembled, flattened container, allows for accurate folding of the carton when it is erected from its partially assembled, flattened configuration. More especially, the “fixing” of fold line ‘F’ in the partially assembled flattened container, prevents the fold line from moving as the carton is erected, thus ensuring accurate alignment in the erected carton.

Another advantage of the invention is that the erected, but unsealed, carton is more rigid than conventional prior art designs. As the carton passes along the automated packaging line, an inward lateral pressure is applied to the carton to grip it. This allows the carton to be held upright and to be moved downstream along the packaging line. The amount of pressure which is applied can be adjusted. As conventional cartons have less rigidity, relatively little pressure can be applied before parts of the carton become mis-aligned. Equally, as relatively little pressure can be applied, it is quite easy for the lid to be mis-aligned as it is sealed to the carton. In contrast, in the present invention, the greater rigidity of the carton allows greater pressure to be applied, which facilitates the correct alignment of the lid relative to the carton and thus correct sealing of the lid to the carton.

Claims

1. A partially-assembled, flattened container which can be erected into a fully-assembled carton by a “pop-up” action, the partially-assembled flattened container being formed from a foldable substrate, and comprising two panels each of which is adapted and configured to form a respective triangular side wall, panel forming an entire respective side wall from a single continuous piece of substrate, one of said panels being bisected by a fold line so that, in the partially-assembled flattened container one of the two halves of the bisected panel overlies the other half; two substantially rectangular panels, each of which is adapted and configured to form a respective end wall, wherein, in the partially-assembled container one of said substantially rectangular panels overlies the other; a first flap, at least part of which is secured to one of the aforementioned panels adapted and configured to form a triangular side wall; and a second flap, at least part of which is secured to at least part of the first flap.

2. A flat blank, having fold lines formed therein, adapted and configured for assembly of the blank into a substantially triangular prism-shaped carton for a sandwich, the blank being formed of a foldable substrate and comprising: a) at least a first straight edge and at least a second straight edge which are substantially perpendicular to each other and which facilitate the accurate feeding of the blank into an automated folding and gluing apparatus for folding and gluing the blank, one of the said edges being substantially parallel to the direction of motion of the blank as it is fed into the automated gluing apparatus; b) two panels which each form a respective entire triangular side wall in the assembled carton, and wherein each of which is formed from a respective single continuous piece of substrate material; and c) two substantially trapezoidal flaps one of which adjoins, via fold line, one of the aforementioned panels which forms a triangular side wall in the assembled carton, and wherein the substantially parallel sides of one of said trapezoidal flaps are substantially parallel to the parallel sides of the other of said flaps.

3. A partially-assembled flattened container according to claim 1, or a blank according to claim 2, wherein the substrate is substantially entirely laminated on one side, or on both sides, with a moisture-impermeable transparent film.

4. A partially-assembled flattened container according to claim 1 or claim 3, or a blank according to claim 2 or 3, wherein substantially all of the fold lines therein are formed by creases rather than by cuts or scoring.

5. A partially-assembled flattened container according to any one of claim 1, 3 or 4, wherein one or both of said first and second flaps are substantially trapezoidal.

6. A partially-assembled flattened container according to any one of claims 1 or 3-5, wherein the first and second flaps are arranged and secured such that the second flap overlies part of the first flap, the overlapping parts being secured together.

7. A partially-assembled flattened container according to any one of claims 1 or 3-6, wherein the first flap comprises a fold line which divides the flap into at least two parts.

8. A partially-assembled flattened container according to claim 7, wherein the two parts are asymmetric, and one part is larger than the other.

9. A partially-assembled flattened container according to claim 7, wherein the said fold line comprises a cut, score or kiss cut.

10. A partially-assembled flattened container according to claim 6, wherein the part of the first flap on one side of the fold line therein is secured to the panel which is adapted and configured to form a triangular side wall, and wherein the part of the first flap on the other side of the fold line is secured to the second flap.

11. An apertured blank according to claim 2 or claim 4 as dependent on claim 1, wherein the blank comprises a first pair of straight edges which are perpendicular to one another to facilitate the blank passing through the feed mechanism of an automated folding/gluing machines accurately in a desired orientation; and a second pair of straight edges which are perpendicular to one another which facilitate the blank passing through the feed mechanism of an automated window patching machine accurately in a desired orientation, one of said straight edges being laterally offset from the aperture in the blank, and the other of said straight edges being parallel with the aperture in the direction of travel of the blank through the window patching machine.

12. A blank according to claim 11, wherein the corresponding members of the first and second pairs of straight edges are at about 45° to one another.

13. A method of making a partially-assembled flattened container in accordance with claim 1, preferably using a flat blank in accordance with claim 2; the method comprising the steps of: (a) optionally, forming one or more pre-folds in a flat blank of foldable substrate of appropriate size and shape, (b) folding a first flap to overlie a panel which forms a triangular side wall, and securing at least part of the first flap to the aforementioned panel; and (c) folding a second flap to overlie at least part of the first flap, and securing the second flap to that part of the first flap which it overlies.

14. A method according to claim 13, wherein at least one of said first and second flaps is substantially trapezoidal.

15. A method according to claim 13, wherein both said first and second flaps are substantially trapezoidal.

16. A method according to any one of claims 13-15, wherein each of steps (b) and (c), and step (a) if present, are performed on an automated folding/gluing machine.

17. A method according to any one of claims 13-16, wherein the securing comprises applying adhesive or glue to one or both of the parts of the blank to be secured together.

18. A method according to any one of claims 13-17, wherein step (b) additionally comprises folding a further flap to overlie a panel which forms a substantially rectangular end wall.

19. A method according to claim 18, wherein the further flap is substantially squareshaped.

20. A method according to claim 18 or 19, wherein the first flap and the further flap are folded along the same fold line.

21. A method according to claim 20, wherein the first flap and the further flap are folded substantially simultaneously.

22. A method according to any one of claims 13-21, wherein the first flap comprises a fold line which divides the flap into two parts, and wherein the part of the first flap on one side of the fold line is that which is secured, in step (b), to a panel which forms a triangular side wall, and the part of the first flap on the other side of the fold line is that which is secured, in step (c) to the second flap, such that the fold line is substantially fixed.

23. A method according to any one of claims 13-22 wherein, in step (c), the second flap is brought to overlie the first flap by folding the blank about a fold line which bisects a panel which forms a triangular side wall.

24. A method according to claim 22, wherein performing step (c) creates a V-shaped notch at one end of the substantially fixed fold line.

25. A method according to any one of claims 13-24, further comprising the step of erecting the partially-assembled flattened container into a fully assembled, erected carton.

26. A method of erecting a fully assembled, erected carton adapted and configured to package two or three sandwiches from a partially-assembled flattened container, the method comprising the step of feeding a plurality of partially-assembled flattened containers in accordance with any one of claims 1 or 3-10, or made by the method of any one of claims 13-25, into the feed mechanism of an automated apparatus; and using the apparatus to erect the carton.

27. A method according to claim 26, further comprising the step of inserting sandwiches into the erected cartons, and heat sealing a lid to the carton.

28. A blank substantially as hereinbefore described and with reference to Figure 1.

29. A partially-assembled flattened container substantially as hereinbefore described and with reference to Figures 4-7.

30. A method of making a partially-assembled flattened container substantially as hereinbefore described and with reference to Figures 4-7.

31. A fully-erected carton made from the partially-assembled flattened container according to any one of claims 1 or 3-10.

32. A fully-erected carton as hereinbefore described and with reference to Figures 2 & 3.