WO2011030115A2

WO2011030115A2 - Method and apparatus, a container blank for use in the same, and a container produced therefrom

Info

Publication number: WO2011030115A2
Application number: PCT/GB2010/001725
Authority: WO
Inventors: Jens Kolstad; Lars Aksel Thingelstad
Original assignee: Elopak Systems Ag; Burrows, Anthony, Gregory
Priority date: 2009-09-11
Filing date: 2010-09-13
Publication date: 2011-03-17
Also published as: WO2011030115A3; GB0915929D0

Abstract

The invention is directed to sealing of raw edge portions of packaging sheet material. In one embodiment a J- flap end closure of a carton has, at each of two apices (104) pointing towards each other, two limbs of a hairpin- form cut edge portion of the apex facing each other. The completion of the end closure includes sealing respective sides of those four limbs directly to parts of a stepped-back, inner surface of an outermost sub-panel (26) beyond the J- fold (102). Alternatively, the apices (104) are squeezed against those surface parts, preferably with the input of thermal energy to cause the plastics to flow. Alternatively, sealing fluid, in particular fluid plastics, is applied to the raw edge portions from a supply channel of a profile substantially matching that of the raw edge portion. The invention is particularly applicable to gable -top, slant- top and flat -top liquid packaging cartons.

Description

METHOD AND APPARATUS, A CONTAINER BLANK FOR USE IN THE

SAME, AND A CONTAINER PRODUCED THEREFROM

This invention relates to a method of, and apparatus for, sealing a raw edge portion of a plastics-coated substrate of cellulosic sheet material, as well as a blank for use in the method and a container formed therefrom.

For extended shelf life, it is important to prevent micro-organisms from having access to contents of plastics- coated paperboard cartons, particularly contents which are low in acid and highly nutritious, such as milk and vegetable juices. Such micro-organisms are present in the ambient atmosphere and may also be present in the paperboard itself.

Conventional skiving and hemming can be employed to seal an otherwise raw edge of cellulosic material, but is more practical for a longitudinal seam of a carton than for a transverse seam thereof, because the skiving and hemming can be performed upon an advancing, longitudinal edge of a web to be supplied to a form-fill-seal packaging machine or of a web to have carton blanks cut therefrom and formed into flat carton sleeves in a converting plant.

A conventional bottom (or top) end closure of a plastics-coated paperboard carton comprises two oppositely inwardly folded, end closure sub-panels each divided into three triangular sub-sub-panels and having apices almost touching each other, and two substantially rectangular, oppositely inwardly folded, end closure sub-panels of which a smaller one is the axially inner of the two and a larger one is the axially outer of the two and the axially outermost of the four sub-panels.

A known way of reducing raw edge exposure, disclosed in, for example, EP-A-1, 112, 553 is to fold back axially inwardly a flap of the free edge zone of the smaller sub-panel and to seal it to the inside surface of the larger sub-panel, giving a so-called "J-flap".

GB-A-1 , 397 , 304 discloses a paperboard container having a flat end closure with a hidden pouring spout which can be opened by a lift tab, the pouring spout being closable for protective storage. The container has a tubular body with top and bottom closures thereon. The bottom closure has two substantially rectangular inner and outer sub-panels and two triangularly divided sub-panels, each consisting of a central triangular sub-sub-panel between two fold-back triangular sub-sub-panels. Sealing of the container can be by the addition of a sealing agent or selected heat sealing of a coating material on the container. But the container could be uncoated and be sealed with a sealing agent; however, in most applications it had been found that a coated paperboard container was to be preferred. Sealing may take place between an inner surface tip area of the outer sub-panel and an outer surface tip area of the inner sub-panel and an inner surface tip area of one fold-back sub-sub-panel of each pair and an outer surface tip area of the other fold-back sub-sub-panel of each pair.

US-A- , 332, 345 discloses a bottom closure structure for a liquid-carrying, thermoplastics-coated paperboard carton wherein the overlapped and sealed areas are formed so as to extend in an "X"-shaped configuration across the bottom, with minimal raw edge exposure on the inside. The shapes of the four main bottom panels of the blank from which the carton is formed are such that they accommodate interdigital nesting or overlapping with respect to the bottom section of an adjacent blank prior to the cutting operation on a paperboard roll, thereby resulting in a narrower roll and, hence, a substantial paperboard saving. A tight seal of the bottom closure can be accomplished by causing cut raw edges to enter into positive engagement with each other; moreover, axially inner panels may be so proportioned that the paperboard is crowded together to enhance the tightness of the bottom seal.

US-A- , 702 , 410 discloses a bottom closure for a packaging carton manufactured by folding and sealing of plastics laminated packaging material. To prevent the absorption of liquid contents by a fibrous carrier layer of the material on unprotected cut edges a folding pattern is created which ensures that all cut edges at a J-bottom of the carton are situated under protecting parts of the packaging material. To this end, each otherwise triangular central sub-sub-panel is of a trapezium form and has an additional sub-sub-panel at its radially inner end. WO-A1-0128862 discloses a pressure pad having sculpted quadrantal regions and suitable for use in the heat-sealing of a substantial range of J-bottom folding designs for closing the bottom of a carton. The pressure pad includes a pattern of sculpting of that surface thereof which is presented to the infolded panels of the bottom of a laminated paperboard carton, so as to provide a pressure pad that is substantially universal with respect to its ability to effect repeatedly the desired heat-sealing of a plurality of geometrically differing combinations of bottom panels defining the bottoms of paperboard cartons.

WO-A-2006079834 discloses a plastics-coated paperboard blank comprising a row of body sub-panels, and a row of J- bottom, end closure sub-panels extending substantially parallelly to the row of body sub-panels, whereof each end closure sub-panel has an edge, and whereof each of second and fourth end closure sub-panels has oblique lines of weakness which divide its sub-panel into a central sub-sub-panel adjacent the corresponding second or fourth body sub-panel and two end sub-sub-panels adjacent the corresponding edges, wherein the end sub-sub-panels bulge away from its corresponding edge. A carton formed from the sheet material blank and a method of forming the carton is also described. The method involves the use of a mandrel cap including a bearing surface and a bridging surface portion substantially flush with the bearing surface, and extending between recessed surface portions at respective opposite sides of the bridging surface portion. In sealing the bottom end closure the apices of the triangularly folded sub-panels are pressed and sealed against the plastics coating of the axially inner surface of the axially inner sub-panel of the first and third sub-panels .

According to one aspect of the present invention, there is provided a method comprising providing sheet material comprised of a plastics-coated substrate of cellulosic material, cutting and forming said sheet material so as to produce a partially completed container having an edge portion of said material including a raw edge portion of said substrate exposed to the atmosphere at the interior or exterior of the container, and completing said container, said completing including performing an operation at said raw edge portion to reduce the exposure of said raw edge portion to the content of the interior of the container or to the atmosphere at the exterior of the container, as the case may be.

According to another aspect of the present invention, there is provided apparatus comprising cutting and forming devices arranged to cut and form sheet material comprised of a plastics-coated substrate of cellulosic material so as to produce a partially completed container having an edge portion of said material including a raw edge portion of said substrate exposed to the atmosphere at the interior or exterior of the container, and completing devices arranged to complete said container, said completing devices including a performing device arranged to perform an operation at said raw edge portion to reduce the exposure of said raw edge portion to the content of the interior of the container or to the atmosphere at the exterior of the container, as the case may be.

Owing to these aspects of the invention, it is possible to lessen the exposure of the raw edge portion to the content of the container (if the raw edge portion is at the inside of the container) or to the ambient atmosphere (if the raw edge portion is at the outside of the container) . Reducing the exposure of the raw edge portion to the content of the interior of the container also has the effect of reducing the exposure of the content to undesirable substances in the cellulosic substrate, in particular undesirable microorganisms .

The raw edge portion may be of a top closure or of a bottom closure, for example a J-flap closure, of the container .

In one embodiment of the invention, in which a cut face of the edge portion of the sheet material is beyond a step- back shoulder between surface parts of the partially completed container and faces a cut face of another edge portion of the material, the completion of the container includes sealing those two edge portions directly to the stepped-back surface part. In the case of an end closure having a J-flap, that surface part would be of the axially inner surface of the axially outermost sub-panel.

A sheet material blank for forming an end closure having a J-flap comprises a layer of cellulosic material and a layer of thermoplastics material, the blank comprising a row of body sub-panels comprised of first, second, third and fourth body sub-panels, and a row of end closure sub-panels extending substantially parallelly to the row of body sub- panels and comprised of first, second, third and fourth end closure sub-panels, whereof each of the second and fourth end closure sub-panels has first and second oblique lines of weakness which divide its sub-panel into a central sub-sub- panel adjacent the corresponding second or fourth body sub- panel and two end sub-sub-panels, each of the central sub- sub-panels being substantially triangular and extending from a corresponding body sub-panel to an apex and whereof the first end closure sub-panel has a central J-flap, the J-flap being separated from its sub-panel by a line of weakness parallel to the row of body panels, wherein that line of weakness is off-set towards the row of body sub-panels relative to an imaginary line passing through both of the apices, the arrangement being such that, upon folding of the end closure sub-panels and sub-sub-panels to form the end closure, the two limbs of the hairpin-form cut edge portion of each apex come to lie with respective sides on the axially inner surface of the second end closure sub-panel.

A corresponding container of sheet material comprised of a layer of cellulosic material and a layer of thermoplastic material includes

a loop of body parts comprised of first, second, third and fourth body parts,

an end closure including inner and outer, substantially rectangular wall parts extending from respective edges of the first and third body parts, with the outer part overlapping the inner part externally of the inner part, and also including first and second groups of substantially triangular wall parts,

the first and second groups of substantially triangular wall parts comprising respective inner, substantially triangular, wall parts extending from the second and fourth body parts, respectively, to respective apices adjacent each other, and respective pairs of outer, substantially triangular, wall parts extending from the respective inner, substantially triangular wall parts, and from the inner and outer, substantially rectangular, wall parts,

the inner, substantially rectangular, wall part including a J-flap projecting centrally with respect to the remainder of that wall part, the J-flap being folded back face-to-face upon that remainder and sandwiched between that remainder and the outer, substantially rectangular, wall part, wherein the apices lie off a line along which the J- flap is folded back, and the two limbs of the hairpin-form cut edge portion of each apex are sealed with respective sides thereof to the axially inner surface of the outer substantially rectangular, wall portion.

In another embodiment of the invention, in which folding of the sheet material such that there is a plastics layer at the outside of the fold leaves exposed at one end of the fold the raw edge portion of the substrate, the completion of the carton includes squeezing that one end of the fold, preferably with the input of thermal energy to cause the plastics to flow to seal the exposed raw edge portion.

In a further embodiment of the invention, the completion of the container includes applying sealing fluid, in particular fluid plastics, to the raw edge portion from a supply channel of a profile substantially matching that of the raw edge portion.

The invention is particularly applicable to gable-top, slant-top and flat-top liquid packaging cartons.

In order that the invention may be clearly and completely disclosed, reference will now be made, by way of example, to the accompanying drawings, in which: -

Figure 1 is a plan view of a known blank from which is produced a known liquid packaging, gable-top, carton having a J-bottom closure, the carton being one used for containing products in respect of which exposure to foreign substances, such as undesirable micro-organisms or gases, is of significant concern,

Figure 2 is a fragmentary top plan view of the known "J" bottom closure,

Figure 3 is a fragmentary vertical section taken on the line III-III of Figure 1,

Figure 4 is a view similar to Figure 2 but of an example according to the present invention,

Figure 5 is a view similar to Figure 3 but along the line V-V of Figure 4,

Figure 6 shows a fragmentary section along the line IV-

IV in Figure 5,

Figure 7 shows a section corresponding to that of Figure 6, but through the carton bottom and a mandrel cap at a stage in the formation of the carton bottom which is before that illustrated in Figure 6,

Figure 8 is a diagrammatic, fragmentary end elevation of another example according to the present invention and illustrating an indexing spider of a packaging machine, with only one of the mandrels thereof being shown and carrying a carton sleeve at a stripping station, and

Figure 9 is a diagrammatic, fragmentary end elevation of the example of Figure 8, but with the mandrel at an earlier stage at a bottom heating station 180° from the stripping station.

Referring to Figure 1, the carton blank consists of a row of panels 2 to 10, known as the first to fifth panels, respectively. Score lines 12 and 14 substantially parallel to the row of panels 2 to 10 divide the panels 2 to 10 into a row of substantially rectangular bottom end closure sub- panels 22 to 30 and a row of substantially rectangular top end closure sub-panels 32 to 40. A score line 42 substantially parallel to those rows divides the top end closure sub-panels 32 to 40 into a row of top end closure obturating sub-sub-panels 52 to 60 and a row of top end closure sealing sub-sub-panels 62 to 70. The obturating sub- panels 24 and 28 and the obturating sub-sub-panels 54 and 58 are triangularly sub-divided by oblique score lines 72 into respective, middle, isosceles triangular sub-sub-panels 71 and sub-sub-sub-panels 71' and respective pairs of right- angle triangular sub-sub-panels 73 and sub-sub-sub panels 73' so that the sub-panels 24 and 28 and the sub-sub-panels 54 and 58 can be folded inwardly upon themselves, with the sub- panels 22 and 26 or the sub-sub-panels 52 and 56 simultaneously being folded thereupon. The sub-panel 22, which becomes the inner of the two sub-panels 22 and 26 in the bottom-closed and-sealed carton, is formed at the lower edge of the blank with a pair of parallel cuts 74 perpendicular to the row of panels 2 to 10 and joined at their inner ends by a scoreline 76, so defining a rectangular sub-sub-panel 78. The blank has been cut out of a web of sheet material in a converting plant in which the web has cut therefrom a series of blanks each as shown in Figure 1, where the blank has top, bottom and lateral cut edges 80 to 86. The edge 82 consists of edge portions 82a to 82e at the respective sub-panels 22 to 30. The sheet material comprises a substrate of paperboard and has inside and outside coatings of a good moisture barrier, in particular low density polyethylene (LDPE) , possibly with the interposition of a good oxygen barrier, such as aluminium foil or ethylene vinyl alcohol (EVOH) . In the converting plant, the score lines and the cuts 74 are formed and then the fifth panel 10 is, after skiving and hemming of its cut edge 84, heat-sealed to the inside surface of the panel 2 at a zone along the cut edge 86, whereby the outside coating of LDPE at the edge 84 is sealed in a moisture-tight manner to the inside coating of LDPE at that zone, and the blank is thus formed into a flat carton sleeve open at both ends. This flat carton sleeve is supplied to a form-fill-seal packaging machine which may be generally of the character described and shown in US-A- 3,566,575, the general disclosure whereof is incorporated herein by reference. In the machine, the sleeve is opened into a tubular shape and then received onto a mandrel of a rotary spider, with the bottom closure sub-panels 22 to 30 protruding beyond the radially outer end of the mandrel, the outer end of which is in the form of a mandrel cap having its radially outer surface profiled to match the intended cross- sectional profile of the bottom closure of the carton.

Referring to Figures 2 and 3, the known J-bottom of the gable-top carton has the sub-panels 24 and 28 inwardly folded with the isosceles triangular sub-sub-panels 71 thereof located above the triangular sub-sub-panels 73 thereof, with the substantially rectangular bottom closure sub-panel 22 located beneath the triangular sub-sub-panels 71 and 73, with its outwardly folded-back sub-sub-panel 78 (called the J flap) at the outside of the sub-panel 22 and with the substantially rectangular sub-panel 26 folded onto the sub- panel 22 with the sub-sub-panel 78 located between them. It is in this condition illustrated in Figures 2 and 3 that the bottom closure sub-panels are sealed together. The "J" (22, 78) of the bottom closure can be seen in Figure 3. Moreover, the triangular sub-sub-panel pairs 73 of each of the sub-panels 24 and 28 have their cut edge portions 82b and 82d, respectively, each facing directly towards the other, whereby the raw edge portions of the paperboard substrate of those cut edge portions face towards each other. Moreover, at their tips 100 the raw edge portions tend to provide access ends of leakage channels through which the ambient atmosphere might gain access to the interior of the carton, the content of the carton might gain access to the ambient atmosphere, and/or undesirable micro-organisms in the substrate might gain access to the content. The spacing d between the potential leakage channels and the fold edge 102 of the J is conventionally about 1mm. This means that the apices 100 are very close to the fold edge 102 of the J, so that the potential leakage channels at the apices 104 tend to be held open during bottom sealing, with the consequence that the LDPE in the region of the apices 104, even though relatively fluid, may not block those potential leakage channels at the apices 104.

In order to overcome this problem and as shown in Figures 4 and 5, we propose, by making the cuts 74 about 1 or 2mm. longer and moving the score line 76 correspondingly, to increase the distance d between the apices 104 and the edge 102 to 2 to 3mm. , even though this results in the sub-sub- panel 78 being slightly larger. As a consequence, as illustrated in Figure 5, the apices 104 lie flatly against the internal surface of the sub-panel 26, so that the potential leakage channels at the apices 104 tend not to be held open by the edge 102, with the result that the relatively fluid LDPE can more readily block the potential leakage channels during bottom-sealing.

The embodiment illustrated in Figures 6 and 7 can be applied instead of or additionally to the embodiment shown in Figures 4 and 5. Here, the mandrel cap 106 of each mandrel of the spider is formed, in the region of the apices 104, with a protrusion 108 so that, upon bottom-sealing of the carton between the mandrel cap 106 and a pressure plate at the bottom-sealing station at the spider, the apices 104, which, at least before squashing, point parallelly to the sub-panels 22 and 26, are squashed (as shown in Figure 6) and the inner ends of the potential leakage channels are thereby closed. Furthermore, the protrusion 108 tends to force the relatively fluid LDPE into those inner ends and thereby block them.

One or both of the embodiments shown in Figures 8 and 9 can be used instead of the embodiments of Figures 4 to 7, or in addition to one or both of those embodiments. On a hub 110 of the spider is shown one of the identical mandrels 112 regularly angularly distributed therearound. Co-axially encircling the respective mandrels 112 at the inner ends thereof are substantially annular supply channels in the form of hollow collars 116. A conduit 114 supplies to the hollow collar 116 in the stripping position a liquid sealant, for example molten plastics, in particular molten LDPE. The collar 116 has small holes through which the sealant is extruded onto the substantially annular, upwardly directed, top cut edge 80 of the bottom-sealed carton C having its edge 80 uppermost. The collar 116 and the mandrel 112 are designed in such a way as to match exactly the top configuration of the carton C.

An earlier stage of rotary indexing of the spider is illustrated in Figure 9, in which the bottom cut edge 82 of the carton, before folding, but possibly after pre-breaking, is supplied with a liquid sealant therefor, which again may be liquid LDPE. Mounted around a heater head 118 at the bottom heating station is an annular supply channel 120 with which the mandrel 112 (and its mandrel cap 106) become co- axial at the bottom sealing station and through which the liquid sealant is supplied to the substantially annular, upwardly directed, bottom cut edge 82 of the carton sleeve S, which has its bottom edge uppermost. The channel 120 and the heater head 118 are designed in such a way as to match exactly the bottom configuration of the carton sleeve S.

Claims

A method comprising providing sheet material comprised of a plastics-coated substrate of cellulosic material, cutting and forming said sheet material so as to produce a partially completed container having an edge portion of said material including a raw edge portion of said substrate exposed to the atmosphere at the interior or exterior of the container, and completing said container, said completing including performing an operation at said raw edge portion to reduce the exposure of said raw edge portion to the content of the interior of the container or to the atmosphere at the exterior of the container, as the case may be.

A method according to claim 1, wherein, prior to completion of said container, a cut face of the edge portion of the sheet material is beyond a step-back shoulder between surface parts of the partially completed container and faces a cut face of another edge portion of the material, and said completing includes sealing those two edge portions directly to the stepped- back surface part.

A method according to claim 2, wherein said shoulder is provided by an edge of a J-fold of a J-fold closure of said partially completed container.

A method according to claim 1, wherein said cutting and forming includes folding of the sheet material such that said sheet material leaves said raw edge portion exposed at one end of a fold formed by said folding, as thus does a plastics layer at the outside of the fold, and said completing includes squeezing that one end of the fold.

A method according to claim 4, wherein said squeezing is accompanied by input of thermal energy to cause the plastics of said plastics layer to flow to seal said raw edge portion.

A method according to any preceding claim, wherein said completing comprises applying sealing fluid to said raw edge portion.

A method according to claim 6, wherein said sealing fluid comprises fluid plastics.

A method according to claim 6 or 7, wherein said raw edge portion is substantially annular and said sealing fluid is supplied thereto by a substantially annular channel substantially matching said raw edge portion in profile .

A method according to any preceding claim, wherein said container is a gable-top, slant-top, or flat-top, liquid packaging carton.

A method according to claim 9 as appended to any one of claims 6 to 8, wherein said sealing fluid is applied to a bottom raw edge portion at a bottom heating station in which said bottom raw edge portion is directed upwardly.

11. A method according to claim 9 as appended to any one of claims 6 to 8, wherein said sealing fluid is applied to a top raw edge portion at a stripping station in which said top raw edge portion is directly upwardly.

12. Apparatus comprising cutting and forming devices arranged to cut and form sheet material comprised of a plastics-coated substrate of cellulosic material so as to produce a partially completed container having an edge portion of said material including a raw edge portion of said substrate exposed to the atmosphere at the interior or exterior of the container, and completing devices arranged to complete said container, said completing devices including a performing device arranged to perform an operation at said raw edge portion to reduce the exposure of said raw edge portion to the content of the interior of the container or to the atmosphere at the exterior of the container, as the case may be.

13. Apparatus according to claim 12, wherein said cutting and forming devices serve to provide a cut face of the edge portion of the sheet material beyond a step-back shoulder between surface parts of the partially completed container and facing a cut face of another edge portion of the material, and said completing devices include a sealing device serving to seal those two edge portions directly to the stepped-back surface part .

Apparatus according to claim 12, wherein said cutting and forming devices include a folding device serving to fold the sheet material such that there is a plastics layer at the outside of the fold which leaves exposed at one end of the fold the raw edge portion of the substrate, and wherein said completing devices include a squeezing device serving to squeeze that one end of the fold.

Apparatus according to claim 14, and further comprising a thermal energy inputting device serving to cause the plastics of said plastics layer to flow to seal the exposed raw edge portion.

Apparatus according to claim 12, wherein said completing devices include an applying device serving to apply sealing fluid to said raw edge portion.

Apparatus according to claim 16, wherein said applying device is in the form of an annular supply channel profiled to match said raw edge portion and arranged to apply said sealing fluid downwardly.

Apparatus according to any one of claims 12 to 17 and in the form of a form-fill-seal packaging machine wherein carton sleeves are formed into cartons constituting said containers .

Apparatus according to claim 18 as appended to claim 17, wherein said annular supply channel is fixed relative to and substantially co-axial with an indexing mandrel of said machine.

20. Apparatus according to claim 18 as appended to claim 17, wherein said annular supply channel is included in a bottom heating station of said machine.

21. A sheet material blank comprised of a layer of cellulosic material and a layer of thermoplastics material, said blank comprising a row of body sub-panels comprised of first, second, third and fourth body sub- panels, and a row of end closure sub-panels extending substantially parallelly to said row of body sub-panels and comprised of first, second, third and fourth end closure sub-panels, whereof each of the second and fourth end closure sub-panels has first and second oblique lines of weakness which divide its sub-panel into a central sub-sub-panel adjacent the corresponding second or fourth body sub-panel and two end sub-sub- panels, each of said central sub-sub-panels being substantially triangular and extending from a corresponding body sub- panel to an apex and whereof the first end closure sub- panel has a central J-flap, said J-flap being separated from its sub-panel by a line of weakness parallel to said row of body panels, wherein said line of weakness is off-set towards said row of body sub-panels relative to an imaginary line passing through both of the apices, the arrangement being such that, upon folding of said end closure sub-panels and sub-sub-panels to form said end closure, the two limbs of the hairpin-form cut edge portion of each apex come to lie with respective sides on the axially inner surface of the second end closure sub-panel.

A container of sheet material comprised of a layer of cellulosic material and a layer of thermoplastics material, said container including

a loop of body parts comprised of first, second, third and fourth body parts,

an end closure including inner and outer, substantially rectangular wall parts extending from respective edges of the first and third body parts, with the outer part overlapping the inner part externally of said inner part, and also including first and second groups of substantially triangular wall parts,

the inner, substantially rectangular, wall part including a J-flap projecting centrally with respect to the remainder of that wall part, said J-flap being folded back face-to-face upon said remainder and sandwiched between said remainder and said outer, substantially rectangular, wall part, wherein said apices lie off a line along which said J-flap is folded back and the two limbs of a hairpin-form cut edge portion of each apex are sealed with respective sides thereof to the axially inner surface of said outer substantially rectangular, wall portion.