Field of the invention

The present invention relates to a packaging container blank and a method of producing a gable-top paper or paper-board based packaging container. In particular, the present invention relates to a method of producing an easy opening an aseptic gable-top packaging container having a gable closure, i.e. an aseptic gable-top packaging container that is designed to be opened by pushing open and pulling out a gusset panel of the gable-top to form a pouring spout.

The present invention also relates to a blank for producing an easy opening gable-top paper or paper-board based packaging container and to a packaging container produced from such a blank.

Background

Gable top packaging containers, also known as cartons, are commonly used to distribute pourable products, e.g. liquid consumable products, e.g. dairy products, such as milk, or fruit juices.

A gable top packaging container is produced from a laminate packaging material, which typically comprises a multi-ply paper or paperboard sheet on which is laminated one or a plurality of layers for holding the pourable product and/or prevent migration of air and flavour degrading substances through the paperboard. A layer may typically comprise a polyethylene or an aluminium layer.

The laminate packaging material also typically comprises an inner and an outer heat sealable layer, e.g. made from a thermoplastic polymer.

In production of the packaging container, the laminate packaging material may be cut to form blanks, which may be folded, filled and sealed to form the packaging container.

To facilitate folding of the blank, the blank normally comprises crease lines. As is known in the art, a crease line is an embossed or impressed depression on one side of the paperboard with a corresponding raised ridge or welt on the other side forming a line along which the paperboard is structurally weakened and along which the paperboard will bend or fold in a controlled manner when pressure is applied.

Sealing of the packaging container is typically effectuated by heat seat sealing adjoining heat sealable layers of folded panel sections so that they fuse to form impermeable seams.

Generally, it is advantageous that the seams thus formed are as strong as possible. However, in gable-top packaging containers designed to be opened by pushing open and pulling out gable panels to form a pouring spout, too-a-strong top seal may make it difficult for a consumer to open the packaging container without compromising the structural integrity of the laminate packaging material. In particular, if the top seal is too strong, the laminate packaging material may easily de-laminate or partially de-laminate during a first opening.

Ultra-high temperature processing (UHT), ultra-heat treatment, or ultra-pasteurization is a food processing technology that almost sterilizes liquid food by heating it above 135°C - the temperature required to kill many bacterial endospores - for 2 to 5 seconds. UHT is most commonly used in milk production, but the process is also used for other food products, such as fruit juices, cream, soy milk, yogurt, wine, soups, honey and stews.

A UHT food product packaged in an aseptic or sterile gable-top packaging container typical has an unrefrigerated shelf life of several months. In order to guarantee the shelf life, the container must be hermetically sealed after having been filled. However, providing a gabletop packaging container with a hermetic seal which is also easy to open is a challenge. The present disclosure addresses this challenge and seeks to bring forward a new method of producing a gable-top packaging container, in particular an aseptic gable-top packaging container, allowing easy opening.

Summary of the invention

With the abovementioned challenge and known solutions in mind, and according to a first example aspect, the present disclosure provides a packaging container blank made from a laminate packaging material comprising an inside heat sealable layer and a plurality of topclosure sub-panels, including:

- a first top-closure sub-panel comprising a first top-fin panel;

- a second top-closure sub-panel neighbouring the first top-closure sub-panel and comprising a second top-fin panel; and

- a third top-closure sub-panel neighbouring the second top-closure sub-panel and comprising a third top-fin panel, the second top-fin panel comprising a gable crease line extending across the second top-fin panel between a top edge of the second top-closure sub-panel and a top-fin crease line of the second top-closure sub-panel, which gable crease line partitions the top-fin panel into a first top-fin panel section and a second top-fin panel section; the first top-fin panel section being configured to be sealingly attached to the first top-fin panel during top-sealing of the container; the second top-fin panel section being configured to be sealingly attached to the third topfin panel during top-sealing of the container; and the first top-fin panel section and the second top-fin panel section being configured to be separated from the first top-fin panel and the third top-fin panel, respectively, during opening of the container, providing a pouring spout. The second top-fin panel comprises a first sub-region extending transversally across the blank crossing the gable crease line, in which first sub-region the inside heat sealable layer has been treated to reduce or eliminate its heat-sealing capacity. The first sub-region tapers towards the gable crease line providing a localised narrowing of the sub-region straddling the gable crease line.

The top-fin panel may comprise a second top-fin panel comprising a central sub-region in which the inside heat sealable layer has been left untreated to maintain its heat-sealing capacity, the central sub-region extending along the gable crease line from the top edge to the first sub-region. The central sub-region may straddle the gable crease line. The central sub-region may be arranged mirror-symmetric about the gable crease line.

The second top-fin panel may comprise a second sub-region in which the inside heat sealable layer has not been treated to reduce or eliminate its heat-sealing capacity, the second subregion enclosing the first sub-region.

The second top-fin panel may comprise, along the gable crease line, a first section extending from the top edge, a second section extending from the top-fin crease line and a third section being intermediate the first and second sections, the first and second sections being within the second sub-region and the third section being within the first sub-region.

The first section may be longer than the second section.

The first sub-region may be partitioned by the gable crease line into a first sub-sub region and a second sub-sub region, and the first and second sub-sub regions may be mirror- symmetric about the gable crease line.

The first top-fin panel may comprise a second sub-region and the third top-fin panel may comprise a third sub-region, in which second and third sub-regions the inside heat sealable layer may be treated to reduce or eliminate its heat-sealing capacity, which second subregion and third sub-region may be configured to be folded onto the first sub-sub region and the second sub-sub region, respectively, when the container is produced from the blank.

According to a second example aspect, the present disclosure provides a packaging container comprising a blank according to the first example aspect.

According to a third example aspect, the present disclosure provides a method of producing a gable-top paper or paper-board based packaging container, comprising the steps of

- providing a laminate paper or paper-board packaging material blank comprising an inside heat sealable layer and a plurality of top-closure sub-panels, including:

- a first top-closure sub-panel comprising a first top-fin panel;

- a second top-closure sub-panel neighbouring the first top-closure sub-panel and comprising a second top-fin panel; and - a third top-closure sub-panel neighbouring the second top-closure sub-panel and comprising a third top-fin panel, the second top-fin panel comprising a gable crease line extending across the second top-fin panel between a top edge of the second top-closure sub-panel and a top-fin crease line of the second top-closure sub-panel, which gable crease line partitions the top-fin panel into a first top-fin panel section and a second top-fin panel section;

- reducing or eliminating the heat-sealing capacity of the inside heat sealable layer in a first sub-region of the second top-fin panel, the first sub-region extending transversally across the blank crossing the gable crease line and tapering towards the gable crease line providing a localised narrowing of the first sub-region straddling the gable crease line;

- folding the blank bringing the first top-fin panel section into contact with the first top-fin panel and the second top-fin panel section into contact with the third top-fin panel; and

- top-sealing the blank by sealingly attaching the first top-fin panel section with the first top-fin panel and the second top-fin panel section with the third top-fin panel.

The first sub-region may be enclosed by a second sub-region of the second top-fin panel in which the inside heat sealable layer has not been treated to reduce or eliminate its heatsealing capacity.

Said step of reducing or eliminating the heat-sealing capacity of the inside heat sealable layer may comprise coating the inside heat-sealable layer of the first sub-region with a layer of material inhibiting or preventing the inside heat sealable layers from forming a seal with adjoining panel sections.

Said step of coating the inside heat-sealable layer of the first sub-region may comprise printing a layer comprising a solvent and an anti-sealing material onto the first sub-region.

The printed layer may comprise a grammage or base weight of the anti-sealing material within the range of 0.2 to 0.8 g/m2, e.g. within the range of 0.4 to 0.5 g/m2.

Said step of reducing or eliminating the heat-sealing capacity of the inside heat sealable layer may alternatively comprise subjecting the first sub-region to corona treatment.

According to a fourth example aspect, the present disclosure provides a packaging container made from a paper or paper-board based laminate packaging material comprising an inside heat sealable layer and a plurality of top-closure sub-panels including:

- a first top-closure sub-panel comprising a first top-fin panel;

- a second top-closure sub-panel neighbouring the first top-closure sub-panel and comprising a second top-fin panel; and - a third top-closure sub-panel neighbouring the second top-closure sub-panel and comprising a third top-fin panel, wherein the second top-fin panel comprises a gable crease line extending across the second top-fin panel between a top edge of the second top-closure sub-panel and a star point of the second top-closure sub-panel, which gable crease line is configured to form a pouring spout chute when the container is in an open position and partitions the top-fin panel into a first top-fin panel section and a second top-fin panel section.

The container, when in a sealed state, comprises, along the gable crease line, a first section and a second section where the second top-closure sub-panel is hot-sealed to the first and third top-closure sub-panels, and a third section, which is intermediate the first section and the second section, where the heat-sealing capacity between the second top-closure subpanel and the first and third top-closure sub-panels is reduced or eliminated.

The first section may extend from the top edge towards the star point and the second section extends from the star point towards the top edge.

The length of the first section may be greater the length of the second section.

The length of the first section may be within the range of 0.3-0.5 of the distance between the top edge and the star point.

Above-discussed preferred and/or optional features of each aspect may be used, alone or in appropriate combination, in the other aspects of the invention.

Description of the drawings

Following drawings are appended to facilitate the understanding of the invention:

Fig. 1 is a top view of an outside surface of a prior art.

Fig. 2 is a detailed top view of an inside surface of the blank according to Fig. 1.

Fig. 3 is a schematic cut-through view of a laminate packaging material.

Fig. 4 schematically illustrates a closed gable-top packaging container.

Fig. 5 schematically illustrates a semi -open gable-top packaging container.

Fig. 6 schematically illustrates an open gable-top packaging container.

Figs. 7-9 illustrate an embodiment of a blank according to the present invention.

Fig. 10 illustrates a further embodiment of a blank according to the present invention.

Figs. 11 and 12 illustrate yet another embodiment of a blank according to the present invention. Fig. 13 illustrates yet another embodiment of a blank according to the present invention.

It should be understood that the drawings are not intended to limit the invention to the subject-matter depicted in the drawings.

In the drawings, like reference numerals have been used to indicate common parts, elements or features unless otherwise explicitly stated or implicitly understood by the context.

Detailed description

In the following, specific embodiments of a blank and a container produced therefrom will be described in more detail with reference to the drawings. However, it is specifically intended that the invention as defined in the following claims is not limited to the embodiments and illustrations contained herein but includes modified forms of the embodiments including portions of the embodiments and combinations of elements of different embodiments as come within the scope of the claims.

An embodiment of a prior art blank 100 is disclosed in Figs. 1 and 2. In Fig. 1, the blank 100 is disclosed with the surface configured to form the outside surface of the container facing the viewer. In Fig. 2, the blank 100 is disclosed with the surface configured to form the inside surface of the container facing the viewer

The blank 100 is made from a multi-ply paper or paperboard sheet on which is laminated one or a plurality of barrier layers for holding a pourable product, e.g. a liquid, and/or prevent migration of air and flavour degrading substances through the sheet.

The blank 100 is generally rectangular and comprises a first, bottom edge 101, a second, top edge 103 and parallel, third and fourth, side edges 105, 107. The side edges 105 and 107 are generally rectilinear and parallel, whereas the top and bottom edges 101 and 103 have an irregular shape. The blank 100 also comprises a plurality of crease lines defining folding lines along which the blank 100 is configured to be folded when formed into the container.

The blank 100 comprises five panels, P1-P5, partitioned by longitudinal crease lines 102, 104, 106 and 108 defining folding lines extending across the panel 100 from the bottom edge 101 to the top edge 103. In the present embodiment, the longitudinal crease lines 102, 104, 106 and 108 are generally rectilinear, parallel and continuous, i.e. uninterrupted, and, consequently, extend longitudinally, i.e. vertically in Fig. 1, across the blank 100 between the bottom edge 101 and the top edge 103.

In other embodiments, at least one of the crease lines 102, 104, 106 and 108 may be curvilinear at least along a part-section of the crease line.

Each panel P1-P5 comprises a first sub-panel 110, 112, 114, 116, 118 forming a bottomclosure sub-panel, a second sub-panel 120, 122, 124, 126, 128 forming a wall section subpanel, and a third sub-panel 130, 132, 134, 136, 138 forming a top-closure sub-panel. The bottom closure sub-panels 110, 112, 114, 116 and 118 are configured to form a bottom closure of the container, and the top-closure sub-panels 130, 132, 134, 136, 138 a top closure of the container. The fifth panel P5 is configured to be attached to an inside surface of the first panel Pl adjacent the side edge 105 when the container is formed.

First transversal crease lines 140-148 partition the bottom-closure sub-panels 110-118 from the wall section sub-panels 120-128. The crease lines 140-148 are generally aligned, i.e. arranged one after the other, and extend generally transversally across the blank 100. Likewise, second transversal crease lines 150-158 partitioning the wall section sub-panels 120-128 from the top-closure sub-panels 130-138, are generally aligned and extend generally transversally across the blank 100.

Top-fin crease lines 160-168 extend generally transversally across the blank 100 partitioning sub-sub panels 180-188 of the top-closure sub-panels 130-138 from sub-sub-panels 170-178. Sub-sub panels 180-188 form top-fin panels, or seal lips, of the blank, sub-sub-panels 170 and 174 form roof panels, and sub-sub-panels 172 and 176 form gusset panels.

Gusset panels 172 and 176 each comprises top diagonal crease lines 173a, 173b and 177a, 177b, respectively, partitioning the gusset panel 172, 176 into gusset panel sections 172a- 172c and 176a- 176c, respectively.

Top fin panels 182 and 186 each form a gable seal area and comprises a gable crease line 183 and 187, respectively, partitioning the top fin panel 182, 186 into gable seal area sections 182a and 182b, and 186a and 186b, respectively.

Diagonal crease lines 173a and 173b intersect with gable crease line 183 and top-fin crease line 162 in a star-like point of intersection 193 (see Fig. 1). Likewise, diagonal crease lines 177a and 177b intersect with gable crease line 187 and top-fin crease line 166 in a star-like point of intersection 197. These points of crease line intersection are sometimes referred to as "star-points".

Fig. 2 shows the inside surface of the top-closure region of the blank 100, where the same crease lines, sub-panels and panel sections are indicated by corresponding reference numerals.

Fig. 3 shows a schematic cross-sectional view of an example of a packaging laminate 200 from which the above-discussed blank 100 may be made.

The packaging laminate 200 comprises a bulk layer 202 of paper or paperboard or other cellulose-based material. The bulk layer 202 may be a multi-ply bulk layer, i.e. may comprise a plurality of sub-layers having different characteristics (e.g. having different bulk, different fibre composition etc.). The bulk layer 202 may be any material layer providing dimensional stability and direct or indirect stiffness to the packaging laminate 200, such as preferably a paperboard or carton or other cellulose-based material and may specifically be of a liquid paperboard quality (i.e. such as used for liquid food packages, aseptic liquid food packages and retortable food packages). The packaging laminate 200 in Fig 3 is oriented in a position in which all illustrated layers above the bulk layer 202 are intended to be turned to face outwards, while, correspondingly, all illustrated layers beneath the bulk layer 202 are intended to be turned to face inwards in a packaging container produced from the packaging laminate 200. In other words, the layers above the bulk layer 202 will form the outside of the finished packaging container, while the layers beneath the bulk layer 202 will form the inside of the packaging container, at the same time as the bulk layer 202 constitutes a central layer in the walls, bottom and top of the packaging container. In order to facilitate an understanding of the present invention, the expressions "inside" and "outside" will hereafter be employed taking as the point of departure the central bulk layer 202.

On the inside of the bulk layer 202, the packaging laminate 200 may comprise a barrier layer 204 arranged to prevent migration of oxygen and/or flavour degrading substances through the packaging laminate 200. The barrier layer 204 may be laminated to the inside bulk layer 202 and may be adhered to the bulk layer 202 by any method and/or adhesive known in the art. For example, the barrier layer 204 may be laminated to the bulk layer through an intermediate lamination layer (not shown). The barrier layer 204 may comprise an aluminium foil, polyamide and EVOH barrier layers, vapour deposited and/or metallised films, etc. The intermediate lamination layer may be a thermoplastic material or polymer, such as a polyolefin, preferably low-density polyethylene, LDPE, but could also be another polyolefin, such as polypropylene (suitable for retortable packages), or other thermoplastic polymers, such as carboxylic-group modified polyolefins, such as EAA or EMAA.

Depending on the content to be held by the packaging container, the barrier layer 204 may be omitted.

The packaging laminate 200 comprises an inner heat sealable layer 206. The heat sealable layer 206 serves a purpose of protecting the laminated structure, and in particular the bulk layer 202 and the cellulose fibres therein, from moisture originating from inside of the packaging container. If a barrier layer 204 is present, the heat sealable layer 206 may be laminated to the same. If a barrier layer is omitted, the heat sealable layer 206 may be laminated or otherwise adhered to the inside of the bulk layer 202.

The packaging laminate 200 also comprises an outer heat sealable layer 208. As the inner heat sealable layer 206, the outer heat sealable layer 208 serves a purpose of protecting the laminated structure, and in particular the bulk layer 202 and the cellulose fibres therein, from moisture - in this case from moisture originating from outside the packaging container. The outer heat sealable layer 208 may be laminated to the outside of the bulk layer 202.

The inner heat sealable layer 206 and the outer heat sealable layer 208 may be made from a thermoplastic polymer, e.g. a polyolefin, such as a polyethylene selected from LDPE (low- density polyethylene), LLDPE (linear low-density polyethylene), mLLDPE (metallocene low-density polyethylene) and blends of any thereof. Alternatively, the heat sealable layers 206 and 208 may be made from a heat sealable polypropylene homo- or copolymer, e.g. suitable for retortable packages.

Since the inner heat sealable layer 206 and the outer heat sealable layer 208 have as a purpose to protect the bulk layer 202 from moisture, each layer 206 and 208 should preferably cover inside and outside areas of the packaging laminate 200 that may be subjected to moisture. Advantageously, the layers 206 and 208 cover the whole inside and outside areas, respectively, of the packaging laminate 200.

On sections of the packaging laminate 200 forming visible portions of the packaging container - typically the wall section sub-panels 120-126 and the top-closure sub-panels 130 and 134 (see Fig. 1) - the packaging laminate 200 may comprise a decor layer 210, for example a decorative colour print, such as a printed colour pattern, optionally including text, nouns, marketing brands, logos etc. The decor layer 210 may be printed, e.g. using flexographic techniques, on the outside of the outer heat sealable layer 208. The decor layer 210 may be produced using a halftone reprographic technique where continuous-tone imagery is simulated through the use of dots of ink, varying either in size or in spacing, thus generating a gradient-like effect. Where continuous-tone imagery contains an infinite range of colours or greys, the halftone process reduces visual reproductions to an image that is printed with only one colour of ink, in dots of differing size (pulse-width modulation) or spacing (frequency modulation) or both. Colour printing can be produced by repeating the halftone process for each subtractive colour, e.g. using the CMYK colour model.

As an example, the decor layer 210 may be laid down onto sections of the packaging laminate 200 forming visible portions of the packaging container using flexographic printing and UV cured inks (UV-flexo inks).

As is known in the art, the inner heat sealable layer 206 and the outer heat sealable layer 208 also have as a purpose to form seals when a packaging container is produced from the blank. The packaging container is normally produced from the blank in a filling machine by folding the fifth panel P5 to the first panel Pl and sealing the panels Pl and P5 in a longitudinal seam, e.g. by heat sealing the outer heat sealable layer of panel P5 to a corresponding section of the inner heat sealable layer of panel Pl, thus creating a tubular sleeve. Thereafter, the sleeve is bottom-sealed by folding and sealing the bottom-closure sub-panels 110-118, thus creating an open-top proto-container. Thereafter the pourable product to be held by the container is filled into the proto-container through the open top and, finally, the top-closure sub-panels 130-138 are folded and sealed to each other.

As is known in the art, top sealing the proto container generally involves bringing the topfin panels 180, 182, 184, 186 and 188 into contact with each other and pressing and heating the top-fin panels to thereby heat seal adjoining heat sealable layers of the top-fin panels. In particular, top sealing the proto container generally involves bringing the inside surfaces of top-fin panel sections 186a and 182b into contact with the inside surface of top-fin panel 184 (see Fig. 2) and heat sealing adjoining sections of the inner heat sealable layers of the top- fin panel 184 and the top-fin panel sections 186a and 182b, and, correspondingly, bringing the inside surfaces of top-fin panel sections 182a and 186b into contact with the inside surface of top-fin panel 180 (and the inside surface of interposed top-fin panel 188) and heat sealing adjoining sections of the inner heat sealable layers of top-fin panel 180 (and interposed top-fin panel 188) and top-fin panel sections 182a and 186b.

Furthermore, top sealing involves bringing the outside surfaces of top-fin panel sections 182a and 182b into contact with each other (see Fig. 1) and heat sealing adjoining sections of the outer heat sealable layers of the top-fin panel sections 182a and 182b, and, correspondingly, bringing the outside surfaces of top-fin panel sections 186a and 186b into contact with each other and heat sealing adjoining sections of the outer heat sealable layers of the top-fin panel sections 186a and 186b.

Said top-fin panels and panel sections, when brought into contact with each other, form a top fin and top sealing may be effectuated by pressing and heating the top fin in a suitable pressing and heating tool, e.g. using induction heating or ultra-sound, hot air or high frequency techniques. Fig. 4 is a perspective view of a top-sealed packaging container 300 formed accordingly, comprising a gable closure 302 and a sealed top fin 304.

As far as sealing integrity is concerned, particular care must be taken to provide efficient sealing along the gable crease lines 183, 187, in particular in aseptic containers, e.g. containers intended for holding UHT products. In the sealed container, the gable crease lines 183, 187 extend from the outside of the container to the inside. Consequently, unless efficiently sealed, crease lines 183 and 187 may provide a path for pollutants to contaminate the product inside the container, thus compromising shelf-life. In order to increase sealing efficiency, it is known to provide panels P2 and P4 as so called "pointed panels", i.e. panels where the lateral extent of the top-fin panels 182 and 184 is greatest in the area of the gable crease lines 183, 187. This will extend the length of the crease lines 183, 187 and, consequently, allow a larger sealed area than otherwise would have been possible. In the blanks disclosed in Figs. 1 and 2, panels P2 and P4 are "pointed panels" as is evidenced by the top edge 103 in panels P2 and P4 not being rectilinear but forming an obtuse angle at the point of intersection with the gable crease line 183 and 187, respectively. However, having a larger sealed area will also make it more difficult to open the packaging container.

With reference to Figs. 5 and 6, opening the packaging container 300 generally involves a first step of breaking the seal formed between the outside surfaces of top-fin panel sections 182a and 182b (see Figs. 1 and 5) and a subsequent, second step of breaking the seals formed between the inside surfaces of top-fin panel 184 and top-fin panel section 182b, and between the inside surfaces of top-fin panel 180 and top-fin panel section 182a, respectively (see Figs. 2 and 6).

The top-fin panel sections 182a and 182b are congruent, i.e. they are identical in size and shape. Consequently, when the packaging container 300 is in a closed position, the top-fin panel sections 182a and 182b abut one another in a contact region which generally corresponds to the region of the top-fin panel section 182a and 182b, respectively.

In the open position of the packaging container 300, the top-closure sub-panel 132 (see Fig. 1) forms a pouring spout 306 (see Fig. 6). In particular, the inside surfaces of top-fin panel sections 182a and 182b form pouring lips of the pouring spout 306. Gable crease line 183 (see Fig. 2) forms a pouring spout chute 310, i.e. a bottom of the pouring spout 306, when the container 300 is in an open position.

Figs. 7-9 illustrate an embodiment of a blank 100' according to the present invention. The blank 100' generally corresponds to the blank 100 disclosed in Figs. 1 and 2, but blank 100' has additionally been treated to reduce the opening force required in the above-discussed second step of opening the container.

In the blank 100', the top-fin panel 182 comprises a sub-region 72 in which the inside heat sealable layer 206 has been treated to reduce or eliminate its heat-sealing capacity. In other words, in sub-region 72 the ability of the inside heat sealable layer 206 to form a seal with adjoining panel sections is inhibited. Top-fin panels 180 and 184 comprise corresponding sub-regions 70 and 74.

Sub-region 72 comprises sub-sub regions 72a and 72b, which are partitioned by the gable crease line 183. Sub-sub regions 72a and 72b are mirror images of one another but otherwise congruent. In other words, sub-sub regions 72a and 72b are mirror-symmetric about the gable crease line 183.

Sub-region 70 is generally a mirror image of sub-sub region 72a about the crease line 102. Likewise, sub-region 74 is generally a mirror image of sub-sub region 72b about the crease line 104. Consequently, when the blank 100' is folded to form a packaging container, subregion 70 will be folded onto sub-sub region 72a and sub-region 74 will be folded onto subsub region 72b.

As can be most clearly seem in Fig. 8, sub-region 72 is surrounded by a second, un-treated sub-region 82 of the top-fin panel 182, in which second sub-region 82 the heat-sealing capacity of the inside heat sealable layer 206 is left unaffected. In other words, in sub-region 82 the heat-sealing capacity of the inside heat sealable layer 206 is not inhibited.

Consequently, when a container made from the blank 100' is top-sealed, the inside surface 206 of the top-fin panel 182 will form a "normal" seal with the inside surface 206 of top-fin panels 180 and 184, respectively, only in sub-region 82. In the interface between sub-region 72 and sub-regions 70 and 74, respectively, the seal will be inhibited, thus facilitating the above-discussed second opening step. Preferably, treatment of sub-regions 70, 72 and 74 is such that the inside layer 206 is prevented from creating a seal altogether.

In the transversal direction of the blank 100', the sub-region 82 extends continuously along the top edge 103 and also along the crease line 162, thus forming a first uninterrupted sub- sub region or band 82a along the top edge 103 and a second uninterrupted sub-sub region or band 82b along the crease line 162. Also, on either side of sub-region 72, sub-region 82 comprises sub-sub regions 82c and 82d. Consequently, when a container made from the blank 100' is top-sealed, the interfaces between sub-region 72 and sub-regions 70 and 74, respectively, will form an internal region or layer completely surrounded by a hermetically sealed boarder, in which internal region there is no seal between the inside layers 206 or, at least, where the seal is weakened.

As is most clearly illustrated in Fig.8, the sub-region 72 comprises a first, substantially rectilinear, lower boundary line 76a running substantially parallel to the top-fin crease line 162. The sub-region 72 further comprises second and third substantially rectilinear boundary lines 76b and 76c, forming sides of the sub-region 72, running at an angle of approximately 45 degrees to the crease lines 102 and 104, respectively. Also, the sub-region 72 comprises a fourth, upper boundary line 76d running substantially parallel to the top edge 103.

However, in a region straddling the gable crease line 183, the upper boundary line 76d deviates towards and approaches the lower boundary line 76a, thus creating a narrowing or waist where the lateral distance between the boundary lines 76a and 76d is reduced. In other words, in the transverse direction of the blank 100', the sub-region 72 displays a taper or narrowing centred around the gable crease line 183. In the disclosed embodiment, the taper or narrowing is defined by substantially rectilinear boundary line segments 76d-l, 76d-2 and 76d-3, where segment 76d-2 runs parallel to boundary line 76a and segments 76d-l and 76d-3 run substantially parallel to boundary line 76b and 76c, respectively.

As a consequence of this taper or narrowing, the container produced from the blank 100' will comprise, when sealed, a plug-like sealed region extending from the top edge 103 and down into the top fin along the gable crease line 183, which plug-like region is restricted by boundary line segments 76d-l, 76d-2 and 76d-3.

Consequently, a container made from the blank 100' will, when in a sealed state, comprise, along the gable crease line 183, a first section SI and a second section S2 (see Fig. 9) where the top-fin 182 is hot-sealed to the neighbouring top-fin panels 180 and 184, and a third section S3, which is intermediate the first section SI and the second section S2, where the heat-sealing capacity between the top-fin panel 182 and the top-fin panels 180 and 184 is reduced or, preferably, eliminated. It has been found that this configuration provides a seal fulfilling aseptic requirements while at the same time being easy to open.

In the disclosed embodiment, the length of SI is approximately 4 mm, the length of S2 approximately 1.5 mm and the length of S3 approximately 5.5 mm. Consequently, the length of the gable crease line 183, corresponding to the height of the top fin, is approximately 11 mm. The distance dl between the upper boundary line 76d and the top edge 103 is approximately 2 mm (see Fig. 8) and the distance d2 between the side boundary lines 76b and 76c and the crease lines 102 and 104, respectively, is approximately 5 mm. The panel comprising the top-fin panel 182 may be configured as a "pointed panel", i.e. a panel where the top edge 103 is not rectilinear but forms an obtuse angle at the point of intersection with the gable crease line 183 (see Fig. 8). This will extend the length of the crease line 183 and allow more control in laying out the region S3, i.e. the region where the heat-sealing capacity between the top-fin panel 182 and the top-fin panels 180 and 184 is reduced or, preferably, eliminated. The crease line 162 may also be configured to form an obtuse angle at the point of intersection with the gable crease line 183, i.e. the intersection sometimes referred to as the "star point" 193. This will further extend the length of the crease line 183 and allow even more control in laying out the region S3.

According to one embodiment, said treatment of the sub-regions 70, 72 and 74 comprises coating the inside heat-sealable layer 206 of the sub-regions 70, 72 and 74 with a layer of material inhibiting or, preferably, preventing the inside heat sealable layers 206 from forming a seal with adjoining panel sections. In the following, such a layer will be referred to as an anti-sealing or abhesive layer. The anti-sealing or abhesive layer may typically comprise silicon.

Said coating may comprise printing a layer comprising a water or non-water based solvent and an anti-sealing material onto the sub-regions 70, 72, 74, e.g. utilising a flexographic printing technique. The anti-sealing material may be any material that is capable of covering the inside heat sealable layer 206 and preventing it from merging with or hot-sealing to an adjoining layer. For application of such an anti-sealing solution, an anilox roller may be used.

The grammage or base weight of the anti-sealing material deposited by the anilox roller may be within the range of 0.2 to 0.8 g/m2, e.g. within the range of 0.4 to 0.5 g/m2.

As an alternative to coating the sub-regions 70, 72 and 74 with an anti-sealing layer, the subregions 70, 72, 74 may be subjected to corona treatment. Corona treatment (sometimes also referred to as air plasma treatment) is a surface modification technique that uses a low temperature corona discharge plasma to impart changes in the properties of a surface, in particular the surface energy.

The corona plasma may be generated by the application of high voltage to an electrode that has a sharp tip, at which tip the plasma forms and according to one embodiment the laminate packaging material may be brought to pass such a tip in order to change the surface energy of the inside heat sealable layer 206 in the sub-regions 70, 72 and 74 such that the Dyne level of the inside heat sealable layer 206 is brought to exceed 42 Dyne/cm, more preferably to exceed 45 Dyne/cm, and even more preferably to exceed 50 Dyne/cm. According to one embodiment, the inner heat sealable layer 206 in the sub-regions 70, 72 and 74 is corona treated to a Dyne level within the range of 50-60 Dyne/cm.

Fig. 10 illustrates another embodiment of a blank 100" according to the present invention. The blank 100" corresponds to the blank 100' disclosed in Figs. 7-9, but in blank 100" sub- regions 70 and 74 have been omitted. Consequently, in blank 100" the reduction or elimination of the heat-sealing capacity of the inner heat-sealable layer is provided solely by sub-region 72. The mechanisms reducing the opening force required in the above-discussed second step is otherwise the same as previously discussed.

Figs. 11 and 12 illustrate yet another embodiment of a blank 100"' according to the present invention. The blank 100"' corresponds to the blank 100' disclosed in Figs. 7-9, except in blank 100'" the narrowing of the sub-region 72 in the region of the gable crease line 183 is provided by boundary lines 76d-l and 76d-3 meeting at a right angle on the gable crease line 183. Consequently, as compared to the embodiment disclosed in Figs. 7-9, the waist of the sub-region 72 will be narrower and the plug-like seal will be V-shaped.

In the embodiment disclosed in Figs. 11 and 12, the length of SI is approximately 7 mm, the length of S2 approximately 1.5 mm and the length of S3 approximately 2.5 mm.

Fig. 13 illustrates another embodiment of a blank 100"" according to the present invention. The blank 100"" corresponds to the blank 100' disclosed in Fig. 7, except that the treated sub-region 70, 72 and 74 extends to below the top-fin crease line 160, 162 and 164, respectively. However, in alternative embodiments (not disclosed), sub-regions 70 and 74 in Fig. 13 may be omitted.

In the disclosed embodiment, the treated sub-region 70, 72 and 74 extends approximately 0.5 mm to 1 mm below the top-fin crease line 160, 162 and 164, respectively. However, in alternative embodiments (not disclosed), the treated sub-region 70, 72 and 74 may extend further into the top-closure sub-panel 130, 132 and 134, respectively.

As in the embodiments disclosed in Figs. 7 to 12, the top-fin panel 182 comprises a central sub-region 192 in which the inside heat sealable layer 206 has been left untreated to maintain its heat-sealing capacity, the central sub-region 192 extending along the gable crease line 183 and straddling the same from the top edge 103 to the first sub-region 72. Consequently, in the central sub-region 192 the heat-sealing capacity of the inside heat sealable layer 206 is left unaffected. In other words, in the central sub-region 192 the heat-sealing capacity of the inside heat sealable layer 206 is not inhibited and, consequently, the container produced from the blank will comprise, when sealed, a plug-like sealed region extending from the top edge 103 and down into the top fin along the gable crease line 183 to the first sub-region 72.

It is appreciated that certain features of the invention, which, for clarity, have been described above in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention, which, for brevity, have been described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination.

In the preceding description, various aspects of the blank and container according to the invention have been described with reference to the illustrative embodiment. For purposes of explanation, specific numbers, systems and configurations were set forth in order to provide a thorough understanding of the apparatus and its workings. However, this description is not intended to be construed in a limiting sense. Various modifications and variations of the illustrative embodiment, as well as other embodiments of the apparatus, which are apparent to person skilled in the art to which the disclosed subject-matter pertains, may lie within the scope of the present invention as defined by the following claims.