Packaging container and blank therefor.

(54) NAME Packaging container and its substance (56) PUBLICATIONS QUOTED: --- (57) SUMMARY:

Packaging containers and packaging container blanks of the type used for packaging e.g. milk and juice are often of the so-called roof type, with the top closure also serving as an opening device with a foldable pouring pipe. The pouring pipe (14) forming portions (9, 10) may be partially coated with a seal preventing agent to enable, despite the heat sealing of the top, to release and unfold the pouring pipe. According to the invention, the sealing preventing coating (15) is covered with a film (16) extending along the upper edge region of the packaging container (1), which provides a better defined sealing strength, sealer · top seal and protects said coating (15) both before and after the packaging container blank (15). 2) transformation into packaging containers (1).

PRV 328 ALLF 138 9 132 AA

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The numbers in brackets indicate the international identification code. INID code. Letter mom pin indicates international document code

461 908

The present invention relates to a packaging container of foldable material with bottom and side walls, and to an openable closure comprising two sealed main panels and one of these bellows folds with folding fields whose surfaces facing the main fields comprise a coating of sealing preventing means. The invention also relates to a blank for manufacturing a packaging container of a foldable packaging material which is divided into a number of wall panels for forming bottom, side walls and an openable top closure, which wall panels comprise two main panels and between these folding panels, which later have a coating of a sealant.

Packaging containers of flexible packaging material, e.g. laminates made of paper and plastic, are available in a number of designs. for packaging liquid foods, e.g. milk and juice. A commonly used packaging container of this type is the so-called gable-top, which comprises four side walls, a flat bottom and a roof-like top part which has sloping head panels, the upper parts of which are sealed together to a sealing fin.

In the described type of packaging container, portions of the top part are usually possible to open and form into a pouring pipe. The opening device itself may be designed in a variety of ways, but usually the actual top seal between the upper end of the various wall panels or panels included in the top is also used as the opening device. Thus, when the packaging container is to be opened, the top seal obtained in the manufacture of the packaging container is broken so that some of the folded panels can be folded out to form a pouring pipe. The opening capacity of the packaging container will thereby be largely related to

461 The strength of the 908 top seal, which in practice means that you have to choose between a good and thus tight top seal or an easily opened but less tight top seal. In order to overcome this problem, it has been proposed to separate the sealing and opening function by appropriately supplying the packaging material with another type of opening device, e.g. a perforation line. However, this entails a more complicated manufacturing process and since the perforation line must be placed under the top seal of the packaging container, the opening device comes closer to the liquid surface of the packaging container, which is a disadvantage to both the opening and the pouring of the filling material from the packaging container.

The original design with a combined top seal and opening device is generally preferred, and therefore, recent attempts have been made to optimize this design to obtain both good seal and tightness as well as good openability. Since the top of the packaging container is usually heat sealed by causing the layers of thermoplastic material located on the outside of the packaging material to fuse, several of these attempts have been made to reduce the sealing strength within the limited area of ​​the top seal in the limited area of ​​the seal packaging, despite maintaining sealing temperature and sealing pressure. This reduction of the sealing strength can e.g. This is achieved by providing the packaging material within the areas to be easily opened with an uneven surface so that the total area of ​​adhesion within this area is reduced (EP-A-185,325). However, this technique has been found to have some drawbacks and in practice it has proved difficult to obtain the predetermined desired sealing strength »This disadvantage can be avoided by another known technique (EP-A-270,869), according to which the areas of the top seal to be openable is provided with a coating of a sealant which can be applied to the packaging material in advance by a printing process. This technology provides an easily opened packaging container that

461 908, however, in certain combinations of sealant and plastic coatings on the packaging material may result in leaky packaging containers. This problem is particularly accentuated in packaging containers of the type to be used for aseptic fillers. In this type of filling material and packaging containers, the density requirements are extremely high, as even so-called micro leaks destroy the sterile conditions and greatly reduce the shelf life of the product.

Another prior art (US-A-4,712,727) utilizes laminated strip pieces comprising layers of an adhesive and placed on those areas of the blank where a limited closure strength is desired, that is, especially on both sides of the folded pouring pipe. However, the handling and placement of the individual strip pieces in the correct position on the blank is difficult to master, and the method is additionally relatively expensive.

From the above it can be seen that until now it has not been possible to provide a roofing-type packaging container at which the top seal was partly easily opened upon the intentional opening of the packaging container, and partly secured a completely tight packaging container. These requirements have been particularly difficult to fulfill in aseptic packaging containers, as even very small channels through the top seal cause the sterility to be broken so that the durability of the product can no longer be guaranteed.

It is therefore an object of the present invention to provide a packaging container of selectable material with a top closure which is easy to open and yet has such tightness that the packaging container can advantageously also be used for packaging aseptic products.

It is a further object of the present invention to provide a packaging container with an opening device which is not afflicted with the disadvantages of the prior art, similar constructions.

It is a further object of the present invention to provide a packaging container with a top seal, the

461 908 sealing and opening properties remain good even at varying sealing temperatures and sealing pressures.

These and other objects have been achieved according to the invention in that a packaging container of foldable material with bottom and side walls and an openable closure comprising two sealed main panels, and a bellows fold with folding fields located between them, the surface of which faces the main fields comprises a coating. of sealants, the feature is characterized by a heat-sealable film extending over the coating of sealants.

Furthermore, preferred embodiments of the packaging container according to the invention have been given the characteristics of the subclaims 2-4.

It is a further object of the present invention to provide a blank for making packaging containers with an openable top closure, which blank is so prepared and prepared that a top seal with the desired tightness and opening properties can be safely provided.

It is a further object of the present invention to provide a substance of this kind which does not suffer from the disadvantages typical of prior art substances.

It is a further object of the present invention to provide a packaging container blank which is particularly well suited for the manufacture of packaging containers of the present invention.

These and other objects have been achieved according to the invention in that a blank for manufacturing a packaging container of a foldable packaging material is divided into a number of wall panels for forming bottom and side walls as well as an openable top closure, which wall panels comprise two main panels and between these folding fields, which have a coating of a sealant, given the characteristics that a film of heat sealable material extends over to the coating field coating sealant.

461 908

Preferred embodiments of the packaging container blank according to the invention have further been given the features set forth in subclaims 6-12.

By providing the packaging container and blank according to the invention with a heat-sealable film which covers the coating of sealant, a well-defined and predictable seal strength is obtained between the heat sealable film and the sealant, the top seal, and the interlocking seal, which is a good seal. heat-sealable film covered sealing surfaces. This ensures a good openness and a good seal, whereby the heat-sealable film effectively contributes to preventing the emergence of channels and micro leaks. This makes it possible to use the packaging container and the substance according to the invention also for packing aseptic fillers in sterile packages.

A preferred embodiment of both the packaging container and the blank according to the invention will now be described in more detail with particular reference to the accompanying schematic drawings, which show only the essential elements for understanding the invention.

Fig. 1 shows a packaging container blank according to the invention.

Fig. 2 shows a section of a packaging container blank according to Fig. 1 in section and partly in a large magnification.

Fig. 3 is a perspective view of a packing container according to the invention in the opened state, whereby parts of the packing container wall have been removed for clarity.

Figure 4 illustrates, on an enlarged scale, a section through a portion of the packaging container of Figure 3 in the closed condition.

The preferred embodiment of both the packaging container and the packaging container blank according to the invention selected by way of illustration is a so-called gable-top package, but the invention is not limited to this type of packaging container or packaging container blank, but can be applied to any type of packaging container.

461 908 packaging containers which utilize a sealed bellows fold such as the opening device. The illustrated roof box packaging container 1 is in its main type of conventional type and the packaging container blank 2 illustrated in Figure 1 (which is a laminate with external thermoplastic layers of known type) thus comprises four side wall panels 3 which are separated by vertical big lines 4. The four side wall panels 3 are provided at their lower ends with four bottom panels 5, which in a known manner can be folded and sealed to form a bottom in the packaging container 1, which, however, has no connection with the invention and is therefore not described in more detail.

The four side wall panels 3 are separated at their upper ends by a horizontal big line 6 from four top fields 7, which are separated by the aforementioned big lines 4. The four top fields 7 comprise two main fields 8 and between these located fields which are divided by inclined big lines. in a central, mainly triangular folding field 9 and two on either side of this located, likewise triangular folding field

10th The top panels 7 have at their upper free end an elongate sealing zone 11, the portions of which are associated with the two main fields 8 are unbroken and substantially rectangular, and whose intermediate portions are divided by smaller vertical lines 13 corresponding to respective folding field 10. In the conventional manner, the blank 2 is further provided with sealing fields as well as additional lines and other details, which, however, are known to the person skilled in the art and are of no importance for understanding the invention.

The two folding fields 10, which together with intermediate folding fields 9 are designed to form a foldable pouring pipe 14 at the finished packaging container, exhibit within the sealing zone 11 a coating 15 of sealant, eg silicone. According to the invention, the seal preventing coating 15 is covered by a heat-sealable film 16, which may be in the form of a strip which extends along the entire length of the seal zone 11 and preferably covers substantially the same. The

461 908 heat-sealable film 16 is sealed to the surface layer of thermoplastic material 2 of the packaging container blank 2 around the seal-preventing coating 15, such that the coating at the finished packaging container is liquid-tightly shielded from the interior of the packaging container. The upper limit of the seal preventing coating 15 preferably coincides with the upper edge of both the packaging container blank 2 and the upper edge of the heat-sealable film 16.

When converting the packaging container blank 2 according to the invention into a roof container type packaging container (Fig. 3), the packaging container blank is folded in known manner along the four bevel lines 4 and sealed together so that a substantially tubular body of square cross section is formed. Thereafter, the bottom panels 5 and the heat seal are inaugurated to form a dense bottom, after which the packaging container is filled with filling material to the appropriate level and top sealed. The top of the top is closed by folding the two main fields 8 together with the associated part of the big line 6 as a hinge, while the folding fields 9 and the folding fields 10 are inaugurated between the main fields 8. The top field's sealing zone 11 is then sealed by heating and compression and subsequent cooling. liquid-tight top seal is obtained.

The appearance of the top seal is shown in Figure 4, which is a section through the upper portion of the packaging container of Figure 3 and shows how the upper sealing zones 11 of both the main panels 8 are sealed to an upright sealing fin 17 enclosing the upper sealing zones 10 included in the sealing zone 11. should form the pouring pipe 14 and thus are coated with the seal preventing agent 15. The figure also shows how the heat-sealable film 16 is located between the different layers of material included in the seal fin 17 and contributes to an increased sealing density. As shown in particular in Figure 4, the sealing zones of the two main fields are directly sealed to each other at the upper part of the sealing fin 17,

461 908 which ensures a very strong and tight seal. At the lower part of the sealing fin 1 *, the folded pouring pipe is sealed with the sealing-changing coating 15 and the heat-sealable film 16 between the two main fields 8, which means that the sealing strength in this area is reduced and determined solely by the adhesion between the sealing-preventing sealing-preventing coating 15 16th As a result, the sealing strength in this area can be precisely defined already in the manufacture of the packaging container blank so that the sealing strength is not significantly affected by other factors, e.g. temperature and pressure when sealing the fin after filling the finished packaging container. The presence of the heat sealable film 16 in the sealing zone also causes additional thermoplastic material to be added, resulting in increased tightness as the material can better fill in the channels and voids that may arise at the seal. This increased density is particularly essential to prevent bacteria from entering aseptic packaging, but can also provide a cost advantage, given the thickness of packaging materials. the liquid-tight thermoplastic layers can possibly be reduced as they: _a now have only liquid-sealing function.

As previously mentioned, the packaging container blank 2 preferably consists of a laminated material comprising a central layer 18 of paper (Figure 2), which is coated on both sides with thin, liquid-tight layers 19 of thermoplastic material. Further, at the side of the packaging container blank which is intended to face inwardly and thus come into contact with the stuffing, the material is provided with a barrier layer 20 of preferably aluminum foil, the surface of which is covered by a further layer 19 of thermoplastic material. Furthermore, from the enlarged area of ​​Figure 2 it can be seen how the inner thermoplastic layer 19 is partially covered by the sealing-preventing coating 15, which in turn is covered by the heat-sealable film 16.

The heat sealable film 16 preferably comprises a heat sealable material, e.g. polyethylene,

461 908 which at the side facing the seal preventing coating has a layer of a material which is sealable to the inside of the packaging laminate. In an inner coating of thermoplastic material, usually LDPE, said layer may conveniently consist of an acrylic acid-based polymer or copolymer, and thus a typical film of this type is a coextruded film having a heat sealing to the polyethylene layer of the packaging laminate of an acrylic acid layer. based polymer or copolymer and a polyethylene layer. The total thickness is about 25 µm, of which the thickness of the LDPE layer is about 75%. When the packaging container is intended for aseptic packaging of sterile filling material or when particularly high gas density requirements are set, the heat-sealable film may further comprise a layer of a barrier plastic, e.g. nylon or polyester. Of course, the heat-sealable film also includes the additional layers that may be necessary to bond the layers contained in the film, i.e. any suitable adhesive material. A typical film for this purpose according to the invention (from the sealable side facing the packaging laminate and facing the seal preventing coating) comprises a layer of an acrylic acid-based polymer or copolymer, a binder layer, a layer of barrier plastic (nylon, polyester etc.), an additional adhesive layer and a heat-sealable material layer, e.g. polyethylene.

As the heat-sealable film 16 in the manufacture of the packaging container blank 2 is applied along the sealing zone 11, the film is heat-sealed to the inside layer of the packaging laminate along the entire length of the film. The heat-sealable film 16 will hereby be strongly connected to said inner layer, while the sealing of the seal-preventing coating 15 becomes weaker and is determined solely by the selected combination of seal-preventing coating and the material type of the film 16 facing the coating 15. When the packaging container blank is to be sealed after reshaping into packaging containers, sealing 461 908 will not be altered or affected by the sealing temperature and sealing pressure by the strength between the sealing preventive coating 15 and the heat sealing film 16, so as to ensure material selection. The portion of the heat-sealable film 16 located above the seal-preventing coating 15 will be strongly sealed to adjacent portions of the sealable film 16, i.e. the portions of the seal film 16 which cover the adjacent halves of the two main fields, at the top of the package. When the packing container is to be opened, the relatively strong sealing between the two main fields 8 is obtained at the upper part of the sealing fin 17, after which the seal between the coating 15 and the film 16 is broken so that the two folding pipes 14 forming the folding fields 10 can be folded out. The portion of the heat-sealable film 16 applied over the sealing-preventing coating 15 will thereby remain on said adjacent portions of the two main fields 8 so that the sealing-preventing coating 15 is exposed along the pouring edge of the pouring pipe. This allows the pouring of the stuffing contained in the packaging container to take place over a clean and even surface which does not exhibit torn parts or quadrilateral tabs from the seal. However, in the area under the seal-preventing coating 15, tabs or residues of the heat-sealable film 16 can be quarantined, but these tabs are at a relatively large distance from the pouring edge of the pouring pipe 14 and in practice do not affect the pouring.

As the packaging material, as previously mentioned, usually consists of a laminate which, among other things, Of course, having an outer (i.e., laterally adjoining) bulk layer of thermoplastic material, this thermoplastic layer according to an alternative embodiment of the invention can be used as the heat sealable film (16) instead of a separately applied strip film. In this case, obviously the seal-preventing coating 15 must be applied immediately under the outer thermoplastic layer of the laminate, i.e. between this and the underlying layer, which, depending on the packaging material type

461 908 may be an additional (inner) thermoplastic layer, a barrier layer, or if barrier layer is missing the central support layer 18 of paper. The application of the sealant is hereby made within the intended range before the heat-sealable film is applied over the entire surface of the packaging material. When the packaging container is to be opened, as in the previously described embodiment of the invention, the seal between the coating and the heat-sealable film (thermoplastic layer) will be broken so that the pouring pipe can be unfolded. Along the lower edge of the coating, the thermoplastic layer will burst, but any resulting quartz residues or flaps will not interfere with the pouring of the filler.

Thus, by applying a heat-sealable film over the sealing preventive coating of the pouring pipe, two advantages are mainly achieved. First, the seal strength in the orifice area can be predetermined and defined in such a way in the manufacture of the packaging container blank that it is not affected by subsequent operations, e.g. the top seal of the packaging container. The sealing strength becomes independent of the quality and type of the coating layer that the packaging container blank exhibits on the side facing the inner packaging container, nor is it affected by other factors such as changing material quality, impurities or mechanical defects. The top seal 1 is otherwise positively affected, since the heat-sealable film serves as an additive, which provides a stronger and more homogeneous seal so that micro leakage can be avoided, which is a significant advantage when the arrangement according to the invention is to be used in packaging containers of aseptic type. Both the seal-preventing coating 15 and the heat-sealable film 16 are easy to apply in connection with the manufacture of the material. The seal-preventing coating can be applied in a precise pattern at the desired location by a relatively simple printing method, while the heat-sealable film can be applied in the form of a continuous, pre-made strip which is heat-sealed to the inner layer of the packaging material.

461 908