FI110088B - Process for producing a discharge port for a liquid package - Google Patents

Description

110088

A method of making a liquid container drain opening

Background of the Invention

The present invention relates to a method for manufacturing an emptying opening in a packaging container for a liquid material, which is made wholly or partly of a packaging laminate consisting of layers of fiber-based material and thermoplastic, provided with a removable closure strip.

Disposable liquid packaging containers are increasingly being used to pack liquid foods such as milk, juice and wine. Typically, these packaging containers are made of prefabricated, laminated packaging material comprising a liquid packaging board core layer, which is covered on at least one and usually both sides by thin liquid and gas-tight thermoplastic layers such as polyethylene layers.

15 Liquid packaging containers are also usually provided with some form of opening device, such as a tear or cut indicator or a removable closure strip which is fluid and gas tightly connected to the drain opening. Typical examples of liquid packages with such opening devices are disclosed, for example, in U.S. Patent No. 5,653,383 and European Patent Application 20,155,600.

With an opening device comprising a pre-pierced drain opening and a removable closure tab sealed liquid and gas tightly over it, ···; has many advantages in that it is easy to use, can be pre-attached to the packing material and is inexpensive. However, when packing liquid fillers, special care must be taken to effectively isolate the raw edge of the packaging laminate exposed by punching from the ····: filler, otherwise the filler will be absorbed into the fibrous backing layer, impairing the laminate's tightness, strength and appearance. Therefore, in order to prevent absorption, it is common for the drain aperture to be provided, in addition to the release liner, with an inner thermoplastic layer located on the side facing the packing laminate filler and. . covering both the drain opening and the area around the opening. The cover layer is then connected to the sealing strip via the drain opening so that the cover layer · tears when the sealing strip is removed, allowing the filler to be discharged through the drain opening. However, in this case also the previously closed raw edge of the laminate is again exposed and the filler is absorbed into the fibrous abundant layer during the emptying process. However, this is not desirable for hygienic and aesthetic reasons.

Aseptic packagings with essentially the same structures as those mentioned above are used for packaging sterile fillers such as sterile milk and sterile Hua. However, the packaging laminate comprises one or more additional layers for improving gas tightness. Aluminum foil and thermoplastic, for example polyethylene, are generally used as the gas barrier. In this case, it is particularly important to avoid contact between the filler and the metal, not only during storage in the sealed container, but also during the emptying step, as well as when storing the remaining fillers in the opened container. This is especially true for acidic fillers such as juice and wine, since contact between these fillers and the metal causes a chemical change that affects the taste of the product.

Previously used solutions to overcome the aforementioned problems in aseptic packaging containers with removable sealing strips have been quite complex and include an inner cover layer which has the function of A disadvantage of prior art has been the use of separate strips only fitted to the base laminate hole as the inner cover layer.

On the other hand, solutions have been proposed in which both the outer and inner cover layers are laminated over the entire basic laminate. For such solutions-T '.; these include, inter alia, problems with the opening arrangement due to the thick film formed on the hole. On the other hand, it has been suggested that the thick film formed on the hole can be weakened at the '···' points that the film is intended to tear when the opening is opened. Such a structure is disclosed, for example, in EP-A-686 567. However, such attenuations substantially impair the gas tightness of the packaging, which is by no means desirable for the purpose of specifically ensuring sufficient gas barrier between the filler and the raw edge of the packaging laminate without, between.

. ·. Also, Fl patent 104,811 discloses a solution in which both the outer and inner cover layers are laminated over the entire perulaminate. However, the solution disclosed in this Fl-35 patent 104,811 differs from the above-mentioned EP-A-686 567, inter alia, in that the hole forming the pouring hole 110088 has already been formed before the closure bolt is attached. Such solutions, in which the sole purpose of the removable closure strip has been to ensure a gas barrier between the filler and the gas surrounding the package, present a number of problems in achieving a sufficient gas barrier. On the other hand, in order to obtain a sufficient gas seal, it is necessary to attach the sealing strip very tightly to the packaging laminate, which makes it difficult to open the package.

One of the major weaknesses of the previously used solutions has been that the packaging material of the packaging container, i.e. the base laminate has contained both a layer of fiber-based material and at least one thermoplastic layer thereto. A hole is formed in this base laminate for the drain opening, after which additional layers of thermoplastic are laminated to close the raw edge of the layer of fiber-based material containing the base laminate. Thus, the thermoplastic layer in the base laminate was in no way involved in sealing the raw edge, whereby the ma-15 material could not be used optimally and, on the other hand, the packages became unnecessarily thick due to the extra layers. Such structures are disclosed, for example, in EP-A-686 567, US-A-5,653,383 and Fl-A-104,811.

The solutions described in the aforementioned U.S. Patent No. 5,653,383 also present various problems both with the opening arrangement itself and with the general construction of the packaging material itself. When both the closure of the raw edge and the closure flap itself are provided by separate strips adapted only to the hole of the base laminate, the opening is closed to such an extent that the rolls used for storing the packaging material are no longer usable. On the other hand, sealing the raw edge by means of a separate strip means that the packaging laminate with the hole for making the empty '···' hole must, by itself, meet the gas and liquid tightness requirements of the packaging at least · '... · for the outer surface, since the strip in question does not contribute to meeting these 30 requirements. Further, such a strip used for sealing the raw edge has to be individually aligned with the hole in the packaging laminate and secured to the edges of the hole, which makes the manufacture. ·. : Again, this is an exacting and complicated process.

BRIEF DESCRIPTION OF THE INVENTION It is an object of the present invention to provide a method for making a drain aperture which does not have the above-mentioned problems. The present invention thus relates to a method for manufacturing an emptying opening in a packaging container for a liquid material which is made wholly or partly of a packaging laminate consisting of a fiber-based material and a thermoplastic layer, the aperture being provided with a release liner forming a first hole of a predetermined size and shape, after which the surface of the body layer is laminated on one side with at least one first thermoplastic layer to form a surface film.

This method of the invention is characterized in that a second hole of a predetermined size and shape is formed in the surface film at the first hole, the edges being inside the first hole, the surface facing the at least one first thermoplastic layer of the base layer is laminated with at least one second thermoplastic layer. sealing strip, and a second thermoplastic layer and sealing strip joined to the opposing sides of the surface layer and the body material permeable hole are joined by heat and pressure to the portions of the first and second thermoplastic layers covering the first hole so as to heat and soften deform and close the raw edge of the hole in the intermediate frame layer.

This procedure achieves several important benefits. The most important of these advantages is that the fibrous material backing layer does not need to be individually laminated with a gas and liquid impervious thermoplastic layer and a raw edge sealing thermoplastic layer, since all of the outer surface of the fibrous material backing layer, On the other hand, the thermoplastic layer to be laminated to the surface of the body material and any other layers that may be laminated on top thereof can be optimized for their properties. · As at the expense of gas and liquid tightness, these properties can then be taken care of by laminating onto the first thermoplastic layer: la. It is well known that the best barrier-:. Films with properties' adhere best to the thermoplastic layers and not to the layers of fiber-based material such as cardboard. Thus, of the thermoplastic films involved in sealing the raw edge, the closest raw edge is a thermoplastic film having optimum adhesion to the backing layer of fiber-based material. On the other hand, all the films laminated onto the 5 layers of fibrous material are involved in the sealing, and these other films used for sealing the raw edge can now be better selected also for the properties important for sealing the raw edge of the fiber layer as gas- and liquid-tight as possible. Further, the layer used to seal the raw edge can be completely laminated in a manner that is now intended to cover the entire base laminate, and no special solutions are required to align it with the hole in the base laminate.

An essential advantage achieved by this method is the excellent gas barrier between the filler and the gas surrounding the package.

In this method, the inner surface of the packaging laminate is laminated with a uniform thermoplastic layer which is not perforated at any stage of the process. Thus, this continuous film can be laminated from a material having excellent barrier properties and achieve an excellent gas barrier without other barrier layers.

Preferably, the thermoplastic layer forming the inner layer of the packaging laminate is extruded as a polyethylene film or an ethylene alpha-olefin barrier multi-layer film. The polyethylene film is preferably low density polyethylene (PE-LD). For example, the barrier membrane film may comprise 25 layers simultaneously extruded by the same extruder. Thus, for example, the film applied against the backing layer of a fiber-based material may be polyethylene, such as PE-LD. The barrier multi-layer film preferably also comprises an ethyl / vinyl alcohol copolymer layer.

In order to improve the barrier properties, or to provide them, if the other thermoplastic layers do not have this property, the first thermoplastic layer forming the topsheet 30 may comprise a suitable barrier plastic such as ethylene alpha-olefin.

Preferably, the durable layer forming the surface layer of the packaging laminate. · The plastic layer is extruded as a polyethylene film or a barrier membrane comprising ethylene alpha-olefin. Preferably, the polyethylene film is low thi. 35 heel polyethylene (PE-LD). For example, the barrier membrane film may comprise five coats extruded simultaneously using the same extruder.

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Rasta. Thus, for example, the film applied against the backing layer of the fibrous material may be polyethylene such as PE-LD, and the second film to be laminated onto this film may comprise more than 50%, such as 80%, of ethylene alpha olefin with the remainder being PE-LD. Other layers of the barrier membrane may be, for example, polyethylene (PE) or polypropylene (PP). Said barrier multilayer film may also comprise layers of adhesive aids. In this way, optimum adhesion to the backing layer of the fiber-based material and also good barrier properties is achieved so that the thermoplastic material providing the barrier properties is not in the outer layer facing the product to be packaged.

In the method of the invention, two holes are formed, the first of which is larger in size, formed in the body material and the second of smaller size in the surface film. A second hole of a predetermined size and shape to be formed in the surface film is formed at the first 15 hole so that the edges of the second hole are inside the edges of the first hole.

Forming both holes can be accomplished in a more conventional manner, such as stamping. It is essential that the surface film, when forming the second hole, partially overlaps the hole 20 in the body material and that this portion of the surface film over the body material hole is sufficient to form a raw edge closure with and closes the 'V. · gas and liquid sealed at the crude edge of the hole in the body layer.

In accordance with the invention, the aperture closure is performed both internally * ;;; with a thermoplastic layer and a removable sealing strip that can be attached from the outside. The sealing strip is sealed to the hole by heat and pressure so that it is sealed to a uniform thermoplastic layer inside the package. Upon removal of the removable sealing strip, the integral thermoplastic layer inside the package 30 ruptures at the hole formed in the first thermoplastic layer attached to the sealing strip so as to form a tapping hole, but the raw edge of the body layer remains closed.

BRIEF DESCRIPTION OF THE DRAWINGS: The invention will now be described in more detail with reference to the accompanying drawings, in which Figure 1 is a cross-sectional view of an exemplary embodiment of the emptying opening according to the invention; poikkileikkausia. Figure 3 is a cross-sectional view of a moniker 5 debris film of an exemplary embodiment of the emptying opening of the invention.

| Detailed Description of the Preferred Embodiment

Fig. 1 illustrates a packaging laminate 1, the manufacturing steps of which are illustrated in steps A to G of Fig. 2. Fig. 2 A shows a backing layer 2 of fiber-based material through which a hole marked by a limiting edge 10 is shown (Fig. 3). 2 B). The base layer is then laminated on one side with a thermoplastic layer to form a surface film 4 (Fig. 2C). Thereafter, a hole is formed in the surface film 4, the edges 5 of which are inside the hole made in the body layer (Fig. 2D). Thereafter, the backing layer is laminated to one side facing the surface layer with a thermoplastic layer 6 to form the inner surface of the packaging laminate (Fig. 2E). Finally, the hole made in the topsheet is covered with a removable sealing strip 7 (Fig. 2F) which is then pressed together tightly with the inner surface 6 of the packaging laminate by means of heat and pressure (Fig. 2G). In this case, the closure strip 7 and the thermoplastic layer 6 forming the inner surface are securely fastened to each other. At the same time, the thermoplastic layers 4 and 6 also taper and melt together, covering the crude edge 3 in a gas-tight, liquid-tight manner. The package can be opened by removing the removable closure strip 7, · ;;; wherein the beverage orifice is formed in the packaging laminate between the cavities 8 shown in Figure 1. In this case, the thermoplastic layers 4 and 6 remain protected against the raw edge 3 of the base layer of non-woven material 25.

• · ·

To improve or provide barrier properties, if the other thermoplastic layers do not have this property, the first thermoplastic layer 4 forming the surface layer: 'may comprise any suitable barrier resin such as ethylene alpha olefin.

Preferably, the resilient plastic layer 4 forming the surface layer of the packaging laminate 1 is extruded in the form of a polyethylene film or an ethylene alpha olefin barrier multilayer film. Preferably, the polyethylene film is a low-density polyethylene (PE-LD). The barrier membrane film may comprise, for example. five layers of T 35 extruded at the same time by the same extruder. Thus, for example, the film applied against the backing layer of the fiber-based material may be polyethylene, such as PE-LD, and the second film to be laminated onto this film may comprise more than 50%, such as 80%, ethylene alpha-olefin, the remainder being PE-LD. In this way, optimum adhesion to the backing layer of the fiber-based material and also good barrier properties is achieved so that the thermoplastic providing barrier properties is not an outer layer facing the product to be packaged. The other layers of the barrier membrane may be, for example, polyethylene (PE) or polypropylene (PP). Said barrier membrane film may also comprise layers of adhesive adjuvants. A preferred adhesive adjuvant is Admer® Adhesive Resin from Mitsui Chemicals.

An advantageous embodiment of the invention is illustrated by way of example in Table 1 and Figure 3, in which the base layer of fibrous material is denoted by a, the first thermoplastic layer 4 forming the surface layer and b the second thermoplastic layer 6 forming the inner layer of the packaging laminate.

Table 1 shows which material each layer of packaging laminate comprises and their preferred amounts.

table 1

Layer Raw Material Quantity (Preferred Quantity) [g / m2] a_Enso Performa__180-230 (210) _ b PE-LD 10-20 (15) c High Barrier Film 80-110 (95) d Adhesive Adhesive 8-12 (10) e pp 25-35 (30) f_PE-LD__3-5 (4) _ g PE-LD 12-22 (17) h Adhesive Adapter 3-5 (4) i EA / AL 6-10 (8) j Adhesive Adapter 3-5 (4) k_PE-LD_ 12-22 (17) _

The invention has been described above on the basis of one exemplary embodiment only, and it will be appreciated that the structure described may be modified to some extent without departing from the scope of the appended claims.

; T Thus, the thermoplastic layer formed on the surface of the backing layer may also contain more than one thermoplastic layer prior to perforation.

I I

110088 9 also a barrier layer of aluminum, for example. The number and nature of layers are primarily determined by the intended use of the packaging. Similarly, the nature and number of layers to be laminated to the inner surface of the backing layer is primarily determined by the desired properties of the package. The layered composition of the finished packaging laminate is, of course, optimized to meet the desired requirements for both the packaging laminate itself and the closure of the raw edge of the hole in the base laminate. In the method according to the invention, the layers necessary for sealing the raw edge are also optimally utilized in the other parts of the packaging laminate 10, thereby avoiding unnecessary thermoplastic layers which are unnecessary for the particular application.

Claims (8)

110088 10 A patent was claimed A method for making a drain aperture in a packaging container for a liquid substance which is made wholly or partly of a packaging laminate consisting of layers of fiber-based material and a thermoplastic material, the aperture being provided with a release liner (1) forming a first hole of a predetermined size and shape in the base material layer (2), after which the surface of the body layer 10 is laminated on one side with at least one first thermoplastic layer (4) to form a surface film, characterized in that a second hole of a predetermined size having the edges (5) inside the edges (3) of the first hole, the surface facing the at least one first thermoplastic layer of the base layer 15 is laminated with at least one second thermoplastic layer (6), the surface layer hole is provided with a sealing strip (7), and a second thermoplastic layer (6) and a sealing strip (7) joined to the opposite sides of the permeable hole 20 through the heat and pressure are connected to each other · the parts of the thermoplastic layer (4, 6) which cover the first hole are heated: · to a softening temperature and treated to form and close. the raw edge (5) of the hole in the intermediate frame layer. Method according to claim 1, characterized in that * ['. wherein said at least one first thermoplastic layer (4) is extruded as an alpha-olefin barrier membrane film. 3. A method according to claim 2, characterized in that the polyethylene is extruded into a layer facing the base layer 30 (2) of the fiber-based material of the barrier multilayer film. Process according to one of Claims 2 or 3, characterized in that at least one layer of said barrier membrane is extruded with polypropylene. Method according to one of Claims 1 to 4, characterized in that said at least one second thermoplastic layer (6) is orally; pressed into a barrier membrane film. 110088 11 6. A method according to claim 5, characterized in that the polyethylene is extruded to form a layer facing the base layer (2) of the fiber-based material of the barrier multi-layer film. A process according to claim 5 or 6, characterized in that the ethyl vinyl alcohol copolymer is extruded into at least one layer of said barrier film. Method according to one of Claims 1 to 7, characterized in that the first and second holes are formed by stamping. 12 110088