Packaging container and blank therefor.

(74) Agent

AB Profor, Ruben Rausings gata, S-221 86 Lund, SE Thorbjørn Andersson, S. Sandby, SE

Niklas Rydh, Malmo, SE

Bjørn H. Christiansen, JK Thorsens Patentbureau AS, Oslo

<td>(54) Designation</td><td>Packaging container of foldable material and blank for making such a container</td>

(56) Quote Publications US 4756426 (57) Summary

Packaging containers and blanks for packaging containers of the type used for milk and juices are often of the coin type, the upper closure also being an opening arrangement, with a pourable spout. The portions (9,10) forming the pour spout (14) may be partially coated with a seal-preventing substance, to allow the pour spout to be detached and folded out despite the heat seal of the top. The seal preventing coating (15) is covered by a film (16) protruding along the upper edge portion of the container (1), providing a more well-defined seal strength and a tighter top seal, as well as protecting the coating (15) both before and after the blank ( 2) is transformed into a container (1).

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BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a foldable material packaging container, having a liquid-tight surface layer and with bottom and side walls and an openable closure, comprising two main panels sealed to each other and opening panels located therebetween, which opening panels comprise folded panels whose surfaces face the main panels. comprises a coating of a sealant.

The invention also relates to a blank for making a packaging container of a foldable packaging material, having a liquid-tight surface layer, which blanket is divided into several wall panels for forming a bottom, side walls and an upper closure which can be opened, said wall panels comprising two main and folding fields located between them and having a coating of a sealant.

Packaging containers of a flexible packaging material, e.g. paper and plastic laminate, are available in a large number of designs, and are used, inter alia, for packaging of liquid foods, e.g. milk and juice. A packaging container of this type commonly used is the so-called coin container, which comprises four side walls, a flat bottom and a top portion having main panels slanted against each other, with upper portions sealed together to form a sealing tab.

In the type of packaging container described, it is generally possible to open parts of the top portion and to shape these into a pour spout. The opening arrangement itself can be designed in many different ways, but usually the existing upper seal between the upper ends of the various wall panels included in the top is used as an opening arrangement. When the container is to be opened, the upper seal formed during the manufacture of the container is broken, so that some of the fields folded in can be folded out to form a pour spout. Consequently, the possibility of opening the container will greatly depend on the strength of the upper seal, which in practice means that a choice must be made between a good and thus dense upper seal and an upper seal which is easy to open, but which is less dense. In order to eliminate this problem, it has been proposed to separate the sealing and opening function by equipping the packaging material in a suitable location with another type of opening arrangement, e.g. a perforation line. However, this results in a more complicated manufacturing process and, since the perforation line must be placed under the upper seal on the container, the opening arrangement comes closer to the liquid surface of the container, which is a disadvantage of opening and pouring of the liquid content from the container.

The original design with a combined upper seal and opening arrangement is usually preferred, and therefore, recent attempts have been made to optimize this design to achieve a good seal and seal and the container is easy to open. Since the top of the container is usually heat sealed by fusion of layers of thermoplastic material located on the outside of the packaging material, many of these experiments were based on a decrease of the sealing strength within the limited range of the upper seal used in opening the container, during maintaining the sealing temperature and sealing pressure. This decrease in the sealing strength can e.g. is achieved by equipping the packaging material within the area which should be easy to open with an uneven surface, thereby reducing the overall attachment area within this area (EP-185,325). However, this technique has been found to cause certain drawbacks, and it has been found difficult in practice to achieve the predetermined desired sealing strength. This disadvantage can be overcome by another known technique (EP-270,869), according to which the area of ​​the top seal to be opened is provided with a coating of a sealant which can be applied to the packaging material in advance by means of a printing process. . This technique produces a container which is easy to open, but which for certain combinations of sealant and plastic coating on the packaging material can cause containers to leak. This problem is especially true for containers of the type used for aseptic content. For this type of content and container, the requirements for sealing are extremely high, since even a so-called micro leakage affects the sterile conditions and significantly reduces the shelf life of the product.

Another prior art (US 4,712,727, US 4,756,426) utilizes laminated portions of strip comprising layers of adhesive and applied to the area of ​​the blank where a limited closing force is desired, i.e. above all on both sides of the strip. folded pour spout. However, the handling and placement of the individual parts of the strip in the correct position on the blank is difficult to perform, and the method is furthermore relatively expensive.

It will be apparent from the foregoing that it has not been possible so far to provide a coin-type container which, on the one hand, the top seal is easy to open when it is desirable to open the container and, on the other hand, a fully sealed container can be secured. . This requirement has been particularly difficult to fulfill for aseptic containers, as even very small channels through the top seal can cause sterility to be damaged, so the durability of the product can no longer be guaranteed.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a foldable packaging container having an easy-to-open upper closure which is nonetheless sufficiently tight for the container to be advantageously used for packaging aseptic products.

Another object of the present invention is to provide a packaging container having an opening arrangement which does not cause the disadvantages which have affected similar, prior art designs.

It is a further object of the present invention to provide a packaging container with an upper closure which has good sealing and good opening properties even at varying sealing temperature and sealing pressure.

A further object of the present invention is to arrive at a subject of this type which is not subject to the disadvantages typical of prior art subjects.

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

The packaging container according to the invention is characterized in that a heat-sealable film covers the coating of sealant and is attached to the surface layer around the coating, so that the coating is shielded in a liquid-tight manner from the inside of the container.

Preferred embodiments of the container according to the invention are characterized by the features of the dependent claims 2 and 3.

The blank according to the invention is characterized in that a film of heat-sealable material covers the coating of sealant on the back-folding fields and is attached to the surface layer around the coating, so that the coating is shielded in a liquid-tight manner.

Preferred embodiments of the subject matter of the invention are characterized by the features of the dependent claims 5-10.

First, by equipping the packaging container and blank of the invention with a heat-sealable film covering the coating of sealant, a well-defined and predetermined seal strength between the heat-sealable film and the sealant, and, moreover, a good seal between the various sealants is obtained. is included in the top seal which is covered by the heat sealable film. In this way, firstly, the container is easily opened and a good seal is obtained where the heat-sealable film effectively helps prevent ducting and micro leakage. This makes it possible to use the packaging container and blank according to the invention also for packaging of aseptic content in sterile packaging.

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

Figure 1 shows a container blank according to the invention.

FIG. 2 shows a portion of a container blank as shown in FIG. 1, in section and partly in strong magnification.

Figure 3 is a perspective view of an open container packaging container according to the invention, with parts of the container wall being omitted for the sake of overview.

Figure 4 shows, on a larger scale, a section through a portion of the container according to Figure 3, in the closed condition.

The preferred embodiment of the packaging container and container blank according to the invention selected by way of illustration is a so-called pattern container, but the invention is not limited to this type of container or container blank, but can be used for any container using a sealed fold-in as opening arrangement. The casing container 1 illustrated is mainly of a conventional type, and the container blank shown 2 (which is a laminate with an outer thermoplastic layer of known type) thus comprises four sidewall panels 3 divided by vertical fold lines 4. The four sidewall panels 3 are at the lower ends provided with four bottom panels 5, which in a known manner can be folded in and sealed to form a bottom in the container 1, which, however, is not part of the invention and is therefore not further described.

The four side wall panels 3 are separated at the upper ends by a horizontal fold line 6 from four top panels 7 which are spaced apart by the above mentioned fold lines 4. The four top panels 7 comprise two main panels 8 and fields located between them and which, by means of inclined fold lines, are divided into a middle, mainly triangular fold-in field 9 and two similarly triangular fold-back fields 10 which are on each side thereof. The top panel 7 has an elongate sealing zone 11 at the upper free end, portions corresponding to the two main panels 8 being unbroken and substantially rectangular, while portions located therebetween are divided by vertical fold lines 13 into smaller portions belonging to the respective folding fields 10. The blank 2 is additionally provided in the usual manner with sealing fields and additional fold lines and other details, which, however, are known to those skilled in the art and are of no importance to the understanding of the invention.

The two fold-back panels 10, which together with the fold-in panels 9 located therebetween are intended to form, in the finished container, a pourable spout 14, are provided within the seal zone 11 with a coating 15 of a sealant, e.g. silicone. The seal preventing coating 15 is covered by a heat-sealable film 16 which may be in the form of a strip extending along the entire length of the seal zone 11 and preferably covering it substantially. The heat-sealable film 16 is attached to the surface layer of the thermoplastic material in the container blank 2, around the seal-preventing coating 15, so that in the finished container this coating is shielded from the inside of the container in a liquid-tight manner. The upper limitation of the seal-preventing coating 15 preferably falls together with the upper edge of the container blank 2 and with the upper edge of the heat seal film 16.

In order to convert the container blank 2 according to the invention to a container-type container (FIG. 3), the container blank is folded in known manner along the four fold lines 4 and joined together to form a substantially tubular element of square cross-section. Then, the bottom panels 5 are folded in and heat sealed to form a liquid-tight bottom seal, after which the container is filled with contents to the appropriate level and the top is closed. The closure of the top occurs by folding the two main panels 8 together with the associated portions of the fold lines as hinges, while folding in the folding panels 9 and the folding panels 10 between the main panels 8. The sealing zones 11 on the top panels are then sealed together by heating and compression and subsequent compression. , so that a liquid-tight upper seal is obtained.

The upper seal is shown in Figure 4, which shows a section through the upper portion of the container shown in Figure 3, and shows how the upper seal zones 11 on the two main panels 8 are sealed together into an upright sealing tab 17 which encloses the upper portions of the folding-back panels 10 which form part of the sealing zone 11 and which are to form the pouring spout 14 and thus are coated with the sealing preventing means 15. The figure shows how the heat-sealable film 16 is located between the various layers of material contained in the sealing tab 17 and contributes to increased sealing in the seal. As can be seen in particular in Figure 4, the sealing zones of the two main fields are sealed directly to each other in the upper portion of the sealing tab 17, which ensures a very strong and tight joint. In the lower portion of the seal tab 17, the folded pour spout with the seal-preventing coating 15 and the heat-sealable film 16 is fixed between the two main panels 8, which means that the sealing strength in this area is reduced and is solely determined by the adhesion between the seal-preventable coating 15 and the heat-sealable. film 15. Thus, the sealing strength within this range can be accurately determined already during the manufacture of the container blank, so that the sealing strength is not affected to any significant extent by other factors, e.g. the temperature and pressure of the tab joining after filling the finished container. The presence of the heat-sealable film 16 in the sealing zone also implies that another thermoplastic material is provided, which results in increased sealing, as the material can better fill, the channels and voids that may occur during the sealing. The increased sealing is particularly important for preventing bacteria from entering aseptic packaging, but also provides an advantage in terms of cost, as it may be possible to reduce the thickness of the liquid-tight thermoplastic layer in the packaging material, as this now only has a liquid seal function. As mentioned above, the container blank 2 preferably consists of a laminated material comprising a central layer 18 of paper (Figure 2), which is coated on each side with thin, liquid-tight layers 19 of thermoplastic material. Further, on the side of the packaging blank which is to face inwardly and thus come into contact with the contents, the material is provided with a barrier layer 20, preferably of aluminum foil, the surface thereof being coated with another layer 19 of thermoplastic material. Furthermore, it is apparent from the enlarged portion of Figure 2 that the inner thermoplastic layer 19 is partially coated with the seal preventing coating 15, which in turn is coated with the heat-sealable film 16.

The heat-sealable film 16 preferably consists of a heat-sealable material, e.g. polyethylene, which on the side facing the seal preventing coating has a layer of a material which can be sealed to the inside of the packaging laminate. With an inner coating of thermoplastic material, usually LDPE, said layer may suitably consist of a polymer or copolymer based on acrylic acid, and a common film of this type is a co-extruded film having a layer of a polymer or copolymer based on acrylic acid intended for heat sealing. to the polyethylene layer in the packaging laminate and a polyethylene layer. The total thickness is about 25 µm, of which the thickness of the layer of LDPE is about 75%. Furthermore, when the container is intended for aseptic packaging of sterile contents, or when particularly high gas seal requirements are set, the heat-sealable film may comprise a layer of a barrier plastic, e.g. nylon or polyester. The heat-sealable film in this case, of course, also includes other layers which may be necessary for joining the layers contained in the film, i.e. any suitable adhesive material. A conventional film for this purpose according to the invention (from the side which can be sealed to the packaging laminate and faces the seal-preventing coating) comprises a layer of a polymer or copolymer based on acrylic acid, a layer of adhesive, a layer of barrier plastic (nylon , polyester, etc.), additional layers of adhesive and a layer of heat-sealable material, e.g. polyethylene.

When the heat-sealable film 16 is applied along the sealing zone 11 during the manufacture of the container blank 2, the film is heat sealed to the inside layer of the packaging laminate along the entire length of the film. The heat-sealable film is thereby firmly attached to the inside layer, while the seal against the seal preventing coating 15 will be weaker, and will be solely determined by the combination of seal preventive coating and the type of material in the film 16 facing the coating 15. When the container blank, after conversion into containers, is to be sealed at the top, the sealing strength between the sealing-preventing coating and the heat-sealable film 16 is not altered, and is not affected by the sealing temperature and sealing pressure, which ensures that the bond strength determined by the choice of material is maintained. During the sealing of the upper portion of the package, the portion of the heat sealable film 16 disposed over the seal preventing coating will be sealed firmly to adjacent portions of the sealable film 16, i.e., the portions of the sealable film 16 covering the adjacent halves of the two main fields. When the container is to be opened, the relatively strong seal between the two main panels 8 formed on the upper portion of the seal tab 17 is first broken, after which the seal between the coating 15 and the film 16 is broken, so that the two fold-back panels 10 forming the pouring spout 14 can be folded out. The portion of the heat-sealable film 16 covering the seal preventing coating 15 will remain on the adjacent portions of the two main panels 8 so that the seal preventing coating 15 is exposed along the pouring edge of the pour spout. This means that the contents of the contents contained in the container can be poured along a clean and even surface, which has no torn parts or residual residue from the seal. However, in the area under the seal-preventing coating 15, residual remnants of the heat-sealable film 16 may be found, but these residues are at a relatively large distance from the pouring edge of the pouring spout 14 and will in practice not affect the pouring.

As the packaging material, as mentioned earlier, usually consists of a laminate having, inter alia, a layer of thermoplastic material (i.e., a layer that later comes into contact with the contents), this thermoplastic layer can of course be used, according to an alternative embodiment of the invention, which the heat-sealable film 16, instead of a separately applied film strip. In this case, of course, the seal-preventing coating 15 must be applied directly below the outer thermoplastic layer of the laminate, i.e. between this and the underlying layer, which, depending on the type of packaging material, may be another (inner) thermoplastic layer, a barrier layer, or, if the barrier layer missing, the middle carrier layer 18 of paper. In this case, the sealant is applied in the affected area before the heat-sealable film is applied to the entire surface of the packaging material. When opening the container is broken, such as for the embodiment of the invention described above, the seal between the coating and the heat-sealable film (thermoplastic layer) so that the pouring spout can be unfolded. The thermoplastic layer will burst along the lower edge of the coating, but any stuck residue that can be formed during the process does not affect the pouring of the contents.

Due to the application of the heat-sealable film to the seal-preventing coating on the pouring spout, two advantages are primarily obtained. First, the seal strength in the orifice region can be predetermined and determined in such a way during the preparation of the container blank that it is not affected by subsequent operations, e.g. the upper seal of the container. The strength of the seal will be independent of the quality and type of coating that the container blank has on the side facing the inside of the container, and it will not be affected by other factors such as varying material quality, contaminants or mechanical breakage. The upper seal is also positively affected, since the heat-sealable film constitutes an additional material which forms a stronger and more homogeneous seal, so that micro leakage can be prevented, which is a significant advantage when the arrangement according to the invention is to be used for containers of the aseptic type. The seal-preventing coating 15 and the heat-sealable film 16 are easy to apply in connection with the preparation of the material. The seal-preventing coating can be applied in an exact pattern at the desired location by a relatively simple printing process, while the heat-sealable film can be applied in the form of a continuous, prefabricated strip heat-sealed to the inside layer of the packaging material.