METHOD FOR APPLYING AN OPENING DEVICE TO A PACKAGING MATERIAL AND PACKAGE OBTAINED THEREBY

Abstract: A method for applying an opening device (3, 3', 3'') to a sheet packaging material for packaging pourable food products, comprising the step of fitting a frame (10, 30) of the opening device (3, 3', 3'') to the packaging material in a position, in which it extends across a crease line (14, 14', 35) designed to define an edge (15, 15', 36) of the finished package (1, 1', 1'').

Description: METHOD FOR APPLYING AN OPENING DEVICE TO A PACKAGING MATERIAL AND PACKAGE OBTAINED THEREBY TECHNICAL FIELD The present invention relates to a method for applying an opening device to a packaging material for packaging pourable food products, and to a package obtained thereby. BACKGROUND ART Many pourable food products, such as fruit juice, UHT milk, wine, tomato sauce, etc., are sold in packages made of sterilized packaging material. A typical example of such a package is the parallelepiped-shaped package for liquid or pourable food products known as Tetra Brik or Tetra Brik Aseptic (registered trademarks) , which is formed by folding and sealing laminated web packaging material. The packaging material has a multilayer structure comprising a layer of fibrous material, e.g. paper, covered on both sides with layers of heat-seal plastic material, e.g. polyethylene. In the case of aseptic packages for long-storage products, such as UHT milk, the packaging material also comprises a layer of oxygen-barrier material defined, for example, by an aluminium film, which is superimposed on a layer of heat-seal plastic material and is in turn covered with another layer of heat-seal plastic material eventually defining the inner face of the package contacting the food product. As is known, such packages are made on fully automatic packaging units, on which a continuous tube is formed from the web-fed packaging material; the web of packaging material is sterilized on the packaging unit itself, e.g. by applying a chemical sterilizing agent, such as a hydrogen peroxide solution, which, after sterilization, is removed, e.g. vaporized by heating, from the surfaces of the packaging material; and the web of packaging material so sterilized is maintained in a closed sterile environment, and is folded and sealed longitudinally to form a vertical tube . The tube is filled continuously from the top with the sterilized or sterile-processed food product, and is sealed and cut at equally spaced cross sections to form pillow packs, which are then folded mechanically to form the finished, e.g. substantially parallelepiped-shaped, packages . Alternatively, the packaging material may be cut into blanks, which are formed into packages on forming spindles, and the resulting packages are filled with the food product and sealed. One example of such a package is the so-called "gable-top" package commonly known by the trade name Tetra Rex (registered trademark) . The above packages are normally provided with reclosable opening devices to permit consumption of, and prevent external agents from coming into contact with, the food product in the package . The opening devices most commonly used at present comprise a frame defining a pouring opening and adapted to be fitted to a hole or a punch-through or pull-off portion in a wall of the package, and a lid hinged or screwed to the frame and which is removable to open the package. Alternatively, other, e.g. slide-type, opening devices are also known to be used. By e.g., WO 98/18608 and WO 98/18609, an apparatus and a method is previously known relating to injection moulding of a plastic material opening device to a hole provided on a sheet of packaging material . The above described opening devices are frequently arranged on the top wall of the package. As is known, the top wall of the package formed from the tube of packaging material has a number of sealing bands which limit the amount of space available in which to provide the opening device. In particular, the top wall is crossed along the centerline by a flat transverse sealing band folded down onto and coplanar with the top wall, and by an end portion of a flat longitudinal sealing band extending perpendicularly from the transverse sealing band. More specifically, the longitudinal sealing band extends along a portion of the top wall of the package, and downwards from the top wall along a lateral wall and a bottom wall of the package . Likewise, spindle-formed packages also comprise a top wall crossed along the centerline by a flat transverse sealing band folded down onto and coplanar with the top wall . In neither case can the opening device be fitted to the sealing bands of the package, which would not only pose problems in sealing the device onto an uneven surface, but would also impair the integrity of the seals themselves . The opening device can therefore only be fitted to the limited flat portions adjacent to the sealing bands extending across the top wall of the package, which obviously limits the maximum size of the opening device. The bigger the pouring hole the better the pouring characteristics. Thus, there is a demand for bigger opening devices giving better pouring, particularly in view of the increasing number of physically different products marketed in packages made of paperlike packaging material, some of which, particularly semiliquid products or products containing fibers or particles,, require a larger opening device for the product to be poured smoothly. Furthermore, the opening device is normally arranged at a distance from the crease lines defining the edges of the top wall in order to avoid that the peripheral edge of the plastic frame disturbs the forming of the package. The bigger the distance between the opening device and the lateral edge of the top wall at the package pouring side, the higher the risk that, during the pouring, the liquid product spills along the adjacent side walls of the package . DISCLOSURE OF INVENTION It is an object of the present invention to provide a method for applying an opening device to a sheet packaging material for packaging pourable food products, designed to provide a straightforward solution to the aforementioned drawbacks typically associated with known methods . According to the present invention, there is provided a method for applying an opening device to a sheet packaging material for packaging pourable food products, said packaging material comprising a plurality of crease lines along which the packaging material itself is folded to obtain a package filled with a pourable food product, said opening device comprising a frame defining a pouring opening and a movable lid for closing said pouring opening, said method being characterized by comprising the step of fitting said frame to said packaging material in a position, in which it extends across one of said crease lines defining an edge of said package . The present invention is also relative to a sealed package for pourable food products made from a sheet packaging material having a plurality of crease lines, said package being provided with an opening device comprising a frame fitted to said packaging material and defining a pouring opening, and a movable lid for closing said pouring opening, characterized in that said frame extends across one of said crease lines defining an edge of said package . BRIEF DESCRIPTION OF THE DRAWINGS A number of preferred non-limiting embodiments of the present invention will be described by way of example with reference to the accompanying drawings, in which: figure 1 is a perspective view of an upper portion of a sealed package for pourable food products in accordance with the present invention; figures 2 , 3 and 4 are bottom plan views of respective alternative embodiments of a frame of an opening device of figure 1 package; figure 5 is a top plan view of a packaging material web portion to which one of the frames of the opening devices of figures 2, 3 and 4 is to be applied to form the figure 1 package; figure 6 is a top plan view of the packaging material web portion of figure 5 provided with the frame of the figure 3 opening device; figure 7 is a section view of the packaging material web taken along line VII-VII of figure 6; figure 8 is the section view of figure 7, after folding of the packaging material web to form the figure 1 package; figure 9 is a perspective view of the upper portion of a sealed package for pourable food products according to another embodiment of the present invention; figure 10 is a perspective view of the upper portion of a sealed package for pourable food products according to a further embodiment of the present invention; and figure 11 is a larger-scale cross section of the upper portion of the figure 10 package. BEST MODE FOR CARRYING OUT THE INVENTION Numeral 1 in figure 1 indicates as a whole a sealed package for pourable food products, e.g. a parallelepiped-shaped package known as Tetra Brik Aseptic (registered trademark) , which is produced from a web 2 of packaging material (shown only partly in figures 5, 6) as described in more detail previously, and is provided with a reclosable opening device 3 made of plastic material and applied preferably to an upper portion of package 1. Package 1 comprises a top wall 4, a base wall (not shown) opposite top wall 4, a front wall 5, a back wall (not shown) , and a pair of side walls 6 (only one of them is shown in figure 1) . The packaging material defining web 2 and package 1 has a multilayer structure (not shown) , and comprises a layer of fibrous material, normally paper, covered on both sides with respective layers of thermoplastic material, e.g. polyethylene. The side of the packaging material eventually contacting the food product in package 1 may also have a layer of oxygen-barrier material, e.g. aluminium, in turn covered with one or more layers of thermoplastic material. Web 2 includes a crease pattern 7, i.e. a plurality of weakened lines obtained by creasing rolls and forming folding lines along which the material is folded during the forming and final folding steps. Preferably, package 1 is made from a continuous tube (not shown) of packaging material, which is obtained by bending and longitudinally sealing web 2 along lateral edges thereof. More precisely, an edge portion of web 2 is superimposed and sealed onto the opposite edge portion so as to obtain a longitudinal seal 8 which has an intermediate portion extending ' along a vertical centreline of the back wall (non shown) of the finished package 1 and opposite end portions extending along the base wall and top wall 4 of the package itself . The tube is then transversally sealed at regular intervals to form transversal seals 9 which extend along the base wall and top wall 4 of the finished package 1. Afterwards, the tube is cut along transversal seals 9 to form so-called pillow packs, which are intermediate products adapted to be transformed into finished packages 1 by means of a plurality of final folding step. With reference to figures 1, 6, 7, and 8, opening device 3 comprises an externally threaded annular frame 10 defining a circular pouring opening 11 through which to pour out the food product contained in package 1, and fitted to the upper portion of package 1 at a hole 12 thereof (figures 5, 7, 8); and a lid or cap 13, which is formed separately from frame 10 and is screwed to frame 10 in a closed position closing pouring opening 11. Once opened, cap 13 is movable between said closed position and an open position detached from frame 10. In particular, hole 7 is punched through web 2 and opening device 3 is fitted to the packaging material before web 2 enters forming, filling and sealing sections of a filling machine (not shown) , wherein web 2 is bent and longitudinally sealed to obtain the above mentioned vertical tube to be filled with the pourable food product . According to the present invention, hole 12 and frame 10 of opening device 3 extend across a crease line 14 defining an edge of package 1; in the embodiment shown in figure 1, crease line 14 defines an horizontal edge 15 of package 1 dividing top wall 4 from front wall 5. Frame 10 of opening device 3 is preferably formed by injecting plastic material through hole 12 and between two mould elements (not shown) cooperating with each other on opposite sides of web 2, so that frame 10 embeds an edge of hole 12 thereby preventing opening device 3 to be removed from hole 12. In particular, during the injection moulding process, the thermoplastic coating of web 2 melt and coalesce with the plastic material of frame 10 at hole 12. Alternatively, frame 10 of opening device 3 may be attached to the packaging material of web 2 by means of gluing or welding through heating elements or ultrasonic sealing elements . With reference to figures 1-4, 7 and 8, frame 10 comprises a flat annular flange 16 fitted to top and front walls 4, 5, and a cylindrical, externally threaded, annular portion 20 projecting from an internal edge of flange 16 and defining pouring opening 11. Flange 16 comprises a circular main portion 21 and a rectangular lateral flap 22 protruding in a coplanar manner from a side of main portion 21. Pouring opening 11 of annular portion 20 is preferably covered by a tear-off seal 23. During forming operations of package 1, flange 16 is bent over crease line 14 so as main portion 21 extends along top wall 4 between crease line 14 and relative transversal seal 9, whilst flap 22 extends along front wall 5. To facilitate the bending of flap 14, flange 16 is provided with a notch, three different embodiments thereof are shown in figures 2 , 3 and 4 and are referenced respectively with numerals 24a, 24b, 24c. Each notch 24a, 24b, 24c extends between flap 22 and main portion 21 and is designed to be placed over crease line 14. Notch 24a has a straight shape parallel to crease line 14, notch 24b has a hourglass shape and notch 24c has a shape resembling an hourglass but where the narrow middle part follows the circumferential external profile of annular portion 20 of frame 10. Straight notch 24a of figure 2 gives the possibility to increase the diameter of pouring opening 11 compared to notches 24b, 24c; however, frame 10 must be placed exactly so that notch 24a comes over crease line 14. The positioning of hourglass-shaped notch 24b in relation to crease line 14 is less critical. In fact, as long as crease line 14 is placed inside the outer limits of notch 24b, frame 10 will bend at said notch. Depending on the position of crease line 14 in relation to notch 24b, package 1 may bulge slightly inwards or outwards at frame 10. This bulging is hardly noticeable at a casual observation. Notch 24c has an hourglass like form. The intention is that crease line 14 should be in line with the broader end parts of notch 24c, which means that frame 10 will slightly protrude with respect toi edge 15 of package 1, as shown in figure 8. In this case, pouring opening 11 may have a larger diameter as it may be placed more closely to or even projecting from crease line 14; therefore, there is less risk of the food product to spill on front wall 5 of package 1 during the pouring. As shown in figure 5, hole 12 has the same profile as flange 16 of frame 10; the outer dimension of hole 12 is somewhat smaller than the outer dimension of flange 16 of frame 10. Thus, when flange 16 of frame 10 is placed over hole 12, the peripheral edge of flange 16 will overlap hole 12. Hole 12 is placed mainly in the part of the web 2 designed to form top wall 4 of package 1, and has an end portion formed in the part of web 2 designed to form front panel 5. As above mentioned, • hole 12 crosses crease line 14 positioned between top wall 4 and front wall 5. With reference to figures 1 and 6-8, cap 13 comprises, integrally, a circular portion 25 closing pouring opening 11, and a cylindrical, internally threaded, annular portion 26 projecting from a circular outer peripheral edge of circular portion 25 and which screws onto annular portion 20 of frame 10. Figures 9, 10 and 11 show the basic principle of the present invention applied to packages 1', 1' ' which will be described only insofar as they differ from package 1 and using the same reference numerals for any parts similar or corresponding to those already described. With reference to figure 9, package 1' differs from package 1 for having a curved front wall 5' and therefore a curved crease line 14', and consequently a curved edge 15', dividing the front wall itself from a top wall 4'. Package 1' is provided with an opening device 3' which is completely similar to opening device 3 and whose parts are referenced with the same numerals of corresponding parts of opening device 3. Frame 10 of opening device 3' has a notch (not shown) , which may be shaped as notch 24a, 24b, 24c, is located at said curved crease line 14' and is imparted with a corresponding curved configuration. Both curved crease line 14' and said curved configuration of the notch of frame 10 of opening device 3' are convex. In all other respects package 1' and opening device 3' of the embodiment of figure 9 correspond to package 1 and opening device 3 discussed above. Thus, frame 10 of opening device 3' comprises a flat annular flange 16' extending across crease line 14' and having preferably a main portion 21 λ arranged on top wall 4' and a flap 22' arranged on front wall 5' . With reference to figures 10 and 11, package 1' ' differs from package 1 only for being provided with an opening device 3'' of the "hinged-type" . Package 1 ' ' has a parallelepiped shape and is delimited by a plurality of walls referenced with the same numerals of the corresponding walls of package 1. Opening device 3' 7 comprises a frame 30 defining a pouring opening 31 and fitted to an upper portion of package 1'' at a hole 32 thereof, and a lid 33 connected to frame 30 by a hinge 34 defining an axis A parallel to top wall 4. Hole 32 and frame 30 of opening device 3'' extend across a crease line 35 defining an edge of package 1' ' parallel to axis A; in the embodiment shown in figures 10 and 11, crease line 35 defines an horizontal edge 36 of package 1 ' ' dividing top wall 4 from an adjacent side wall 6. Lid 33 is moulded integrally with frame 30. Also in this case, opening device 3'' is preferably applied to a packaging material web at a hole 32 thereof before the web enters forming, filling and sealing sections of a filling machine (not shown) , wherein the finished package 1 is formed. In particular, opening device 3'' is preferably formed by injecting plastic material through hole 32 and between two mould elements (not shown) cooperating with each other on opposite sides of the packaging material web, so that frame 30 embeds a peripheral edge of hole 32 thereby preventing opening device 3' 7 to be removed from hole 32. More specifically, frame 30 forms a substantially flat, annular base flange 37, which rests on a first face 39 of the packaging material adapted to define an internal surface of package 1' ' , and a plurality of coplanar fins 38 extending on a plan parallel to base flange 37 and resting on a second face 40 of the packaging material opposite first face 39. Alternatively, frame 30 of opening device 3'' may be attached to the packaging material by means of gluing or welding through heating elements or ultrasonic sealing elements . Frame 30, pouring opening 31 and lid 33 have respective shapes elongated in the direction of transversal seal 9 of top wall 4. Frame 30 further includes a raised annular neck 41 extending from base flange 37 and delimiting pouring opening 31. Base flange 37 of frame 30 is bent over crease line 35 so as a substantially rectangular-shaped main portion 42 of base flange 37 extends along top wall 4, and a tapered end portion 43, opposite hinge 34, of the base flange itself extends along side wall 6; tapered end portion 43 is substantially V-shaped and presents a rounded vertex. To facilitate the bending of frame 30 over crease line 35, base flange 37 has a notch (not visible) which may be shaped as notch 24a, 24b, 24c of opening device 3 and extends along a bottom surface of the base flange itself . Neck 41 forms a flat top flange 45 having a substantially rectangular shape and protruding with respect to the neck itself. Lid 33 comprises a flat main portion 46, which is connected to frame 30 by hinge 34, and a raised substantially U-shaped sealing lip 47 extending from the ends of hinge 34 and projecting from main portion 46 for engagement with neck 41. Lid 33 is originally sealed to an internal edge 44 of top flange 45 of frame 30 surrounding pouring opening 31 by a thin breakable rib 48 extending along a peripheral line around lip 47, and which is broken when lid 33 is unsealed. Internal edge 44 of top flange 45 of frame 30 and lip 47 of lid 33 are conveniently so shaped as to define a cusp shaped pouring beak 50. At pouring beak 50, top flange 45 defines a pouring spout 51 projecting from the neck 41 over crease line 35. Once unsealed, lid 33 is movable between an open position (figure 10) and a closed position (figure 11) , in which lip 47 of lid 33 is retained in fluid-tight manner inside neck 41 of frame 30 by rib 48 snapping beyond edge 4 . At its opposite end to hinge 34, lid 33 forms a pull tab 52 which protrudes outwards with respect to pouring opening 31 at crease line 35 side and faces with base flange 37 of frame 30. Tab 52 defines a handle portion of lid 33 adapted to be pulled upwards by the consumer so as to raise lid 33 and reach open position. Tab 52 is bent towards side wall 6 and is integrally connected at its free end to end portion 43 of base flange 37 by a breakable strip 53 defining a tamper evidence . When tab 52 of lid 33 is pulled upwards, the strip 53 is broken so as to permit the opening of package 1' ' . The advantages of the method according to the present invention and of package 1, 1', 1 ' ' will be clear from the foregoing description. In particular, thanks to the fact that frame 10, 30 of opening device 3, 3', 3'' extends across crease line 14, 14', 35 or edge 15, 15', 36 of package 1, 1', 1", pouring opening 11, 31 of opening device 3, 3', 3'' is positioned immediately adjacent to the above mentioned edge 15, 15', 36, so as to improve the pouring of the food product and to minimize the risk that such product will spill on the walls (5, 5', 6) beneath the pouring opening itself . Since opening device 3, 3', 3'' can cross edge 15, 15', 36 of package 1, 1', 1' ' , more space is available on top wall 4 , 4 ' for accommodating the opening device itself . This means bigger opening devices , with bigger pouring openings, leading to improved pouring. The positioning of opening device 3, 3', 3'' over edge 15, 15', 36 of package 1, 1', 1'' reinforces the edge itself, where it is most vulnerable to damage during transportation and handling. The positioning of opening device 3, 3', 3'' over edge 15, 15', 36 of package 1, 1', 1' ' also provides a package which is more pleasant to drink from directly, because it provides a better "lip feel", i.e., the lips of a consumer do not contact the packaging material, but only the plastic. Consumers in some countries are known to appreciate this improvement . Packages 1, 1', 1'' are less susceptible to errors of positioning of opening device 3, 3', 3'' with respect to adjacent edge 15, 15', 36, since the folding of the packaging material along crease line 14, 14', 35 defining the edge itself is driven by the bending of plastic frame 10, 30 of opening device 3, 3', 3''. Finally, in the case of package l 7 ', the peripheral edge of end portion 43 of base flange 37 rests on vertical side wall 6, so increasing the resistance of pouring beak 50 to external loads, such as loads deriving from transportation and handling, on protruding pull tab 52 . Clearly, changes may be made to the method and package 1, 1', 1 ' ' as described and illustrated herein without, however, departing from the scope of the accompanying claims .

Claims: CLAIMS 1) A method for applying an opening device (3, 3', 3 ' ' ) to a sheet packaging material for packaging pourable food products, said packaging material comprising a plurality of crease lines along which the packaging material itself is folded to obtain a package (1, 1' , 1' ' ) filled with a pourable food product, said opening device (3, 3', 3'') comprising a frame (10, 30) defining a pouring opening (11, 31) and a movable lid (13, 33) for closing said pouring opening (11, 31) , said method being characterized by comprising the step of fitting said frame (10, 30) to said packaging material in a position, in which it extends across one (14, 14' , 35) of said crease lines defining an edge (15, 15', 36) of said package (1, 1' , 1' ' ) . 2) A method as claimed in claim 1, characterized in that said frame (10, 30) of said opening device (3, 3', 3'') is fitted to a hole (12, 32) of said packaging material crossing said one (14, 14', 35) of said crease lines . 3) A method as claimed in claim 2, characterized in that at least said frame (10, 30) of said opening device (3, 3', 3'') is injection moulded directly onto said packaging material . 4) A method as claimed in claim 2, characterized in that said frame (10, 30) of said opening device (3, 3', 3'') is attached to said packaging material by means of an adhesive. 5) A method as claimed in claim 2 or 3, characterized in that said frame (10, 30) of said opening device (3, 3', 3'') is welded to said packaging material. 6) A method as claimed in anyone of the foregoing claims, characterized in that said opening device (3, 3', 3'') is applied to a web-fed packaging material (2) before the web (2) enters forming, filling and sealing sections of a filling machine to produce a sealed package (1, 1', 1'') for pourable food products. 7) A method as claimed in claim 6, characterized in that said frame (10, 30) is furnished with a notch (24a, 24b, 24c) placed in correspondence of said one (14, 14', 35) of said crease lines during the fitting of said opening device (3, 3', 3'') to said web-fed packaging material (2), said frame (10, 30) being bent along said notch (24a, 24b, 24c) when said package (1, 1', 1'') is formed . 8) A sealed package (1, 1', 1'') for pourable food products made from a sheet packaging material having a plurality of crease lines, said package (1, 1', 1'') being provided with an opening device (3, 3', 3'') comprising a frame (10, 30) fitted to said packaging material and defining a pouring opening (11, 31) , and a movable lid (13, 33) for closing said pouring opening (11, 31) , characterized in that said frame (10, 30) extends across one (14, 14', 35) of said crease lines defining an edge (15, 15', 36) of said package (1, 1', 1") . 9) A package as claimed in claim 8, characterized in that said frame (10, 30) of said opening device (3, 3', 3'') is fitted to a hole (12, 32) of said packaging material crossing said one (14, 14', 35) of said crease lines. 10) A package as claimed in claim 8 or 9, characterized in that said one (14, 14', 35) of said crease lines extends between a' first and a second wall (4, 5; 4', 5'; 4, 6) of said package (1, 1', 1''), and in that said frame (10, 30) has a first portion (21, 21', 42) extending along said first wall (4, 4') and a second portion (22, 22', 43) extending along said second wall (5, 5' , 6) . 11) A package as claimed in anyone of claims 8 to 10, characterized in that said frame (10, 30) has a notch (24a, 24b, 24c) placed in correspondence of said one (14, 14', 35) of said crease lines, said frame (10, 30) being bent along said notch (24a, 24b, 24c) . 12) A package as claimed in claim 11, characterized in that said notch (24a) is straight and parallel to said one (14, 14', 35) of said crease lines. 13) A package as claimed in claim 11, characterized in that said notch (24b) has an hourglass shape. 14) A package as claimed in claim 11, characterized in that said notch (24c) has a shape resembling an hourglass in which the narrow middle part follows the periphery of said pouring opening (11, 31) of said opening device (3, 3', 3 7/ ). 15) A package as claimed in anyone of claims 8-14, characterized in that said one of said crease lines is a curved crease line (14 7 ) . 16) A package as claimed in claim 15, characterized in that said notch (24a, 24b, 24c) is located at said curved crease line (14 7 ) and is imparted with a corresponding curved configuration. 17) A package as claimed in anyone of claims 8-16, characterized in that said frame (10) has a cylindrical, externally threaded, annular portion (20) to which said lid (13) is screwed. 18) A package as claimed in anyone of claims 8-16, characterized in that said lid (33) is connected to said frame (30) by a hinge (34) .

Inventors: MOCK ELMAR, MOLIN OLA, TASKINEN SEPPO, MOCK, ELMAR, MOLIN, OLA, TASKINEN, SEPPO
Applicants: MOCK ELMAR, MOLIN OLA, TASKINEN SEPPO, TETRA LAVAL HOLDINGS & FINANCE, MOCK, ELMAR, MOLIN, OLA, TASKINEN, SEPPO, TETRA LAVAL HOLDINGS & FINANCE S.A.
Application year: 2001
Main classification: B65D5
IPC codes: B31B1, B65D5, B65D43