Opening arrangement on a packing container

Abstract: An opening arrangement on a packing container (1) comprising a hole (4) provided in the wall (3) of the container which is covered from above by a flexible strip (6) applied to the outside of the container. The strip has at its one end (6a) an openable portion (9) situated within the hole region which is adapted so as to be torn off to expose a corresponding pouring opening by bending backwards the other end (6b) of the strip, which in unopened position is bent over the hole (4) and is sealed to the underlying portion 9. To retain the strip (6) against the outside of the container, and to prevent contact between the cut edge of the hole (4) and the contents of the container, the strip has a projection (7) directed downwards, accomodated in the hole, whose free end (7a) is folded over round the cut edge and is sealed to the inside of the container wall in a liquid-tight and mechanically strong sealing joint round the whole opening contour of the hole.

Description: The present invention relates to an opening arrangement on a packing container comprising a hole punched out in a wall of the container which is covered from above by a flexible material strip attached to the outside of the container wall whose one end has an opening part situated wholly within the region of the hole, capable of being torn away according to the opening part of claim 1. Such opening arrangement is described in US-A-3 744 662. The plastic tab of this known arrangement is formed relatively complicated so that forming and handling create problems. In packing technology finished consumer packages of non-returnable character have been used for a long time which are manufactured from a material consisting of a carrier layer of cardboard or paper and outer and inner coatings of thermoplastics. Material in these so-called non-returnable packages is often also provided with one or several further layers of other material, e.g. aluminium foil or plastic layers of a different type than those mentioned here. The composition of the packing material sets out from the wish to create the best possible protection for the product which is to be packed, at the same time as it is to provide the package with sufficient mechanical strength to make possible a comfortable handling of the package. To achieve the required mechanical strength which on the one hand gives mechanical protection for the contents and beside makes it possible for the package to be sufficiently rigid in its dimensions so that it can be handled and manually gripped without difficulty, the material in packages of this type is frequently provided with a relatively thick carrier layer of paper or cardboard. Such a carrier layer, however, has no tightness properties towards gases or liquids and the rigidity of the material is quickly lost when it is subjected to moisture or liquid. To impart to the material a good liquid tightness it is provided in most cases with a thin coating of plastic material, and, if the plastic material is a thermoplastics, it may also be used for sealing the plastic layers to one another by means of heat and pressure (so-called heat-sealing) which means that a packing container can be sealed and made permanent in its given shape by heat-sealing overlapping, thermoplastic material panels to one another in a tight and mechanically durable seal. Non-returnable packages of the type described here are manufactured either from blanks punched out beforehand or from a continuous web which has been prepared with suitable decoration and with a pattern of crease lines facilitating the formation of folds. Packing containers are manufactured from a web by joining to one another longitudinal edges of the web in an overlap joint, so as to form a tube, which subsequently is filled with the intended contents and is divided into closed cushionlike container units through repeated flattenings and tranverse sealings of the tube at right angles to the longitudinal axis of the tube. Through appropriate fold-forming of the packing material in the tube the container units are converted to the desired geometrical final shape, usually a parallelepiped. The problem with the abovementioned packages always has been the creation of an opening arrangement which is comfortable to handle and which functions satisfactorily, that is to say which can be opened readily without the use of a tool and which allows an emptying of the contents in a uniform and well-defined jet. One type of known opening arrangements up to now consisted of some form of perforation which extends through the outer plastic layer of the packing container and the carrier layer, whereas the inner plastic layer of the packing container is kept intact. The demand made on such an opening arrangement certainly is that it should be easy to tear up when the package is to be opened, but that it should not be liable to be torn up during normal handling and transport of the package. It will be readily understood, that these two demands are difficult to meet at the same time, since great safety against tearing up during handling of the package implies that the perforation should not weaken to an excessive degree the package wall, which in turn means that greater force will be needed for tearing up the perforation when the package is to be opened. It also has been found that perforations of this kind may give rise to small leakages,which perhaps are not so great as to allow contents to get out, but are still large enough to enable bacteria to penetrate in and infect the contents of the package. A somewhat more readily openable package is that which has been provided with an opening arrangement of the tearing strip (so-called pull-tab) type, Such an opening arrangement usually comprises a hole punched out in the container wall which is closed with the help of a tearing strip attached to the outside of the container wall and which is sealed to a plastic film covering the hole from underneath. The plastic film usually consists of the inner plastic coating of the packing material, but may be a separate plastic strip which has been sealed to the inside of the container wall along a liquid-tight sealing joint round the whole opening contour of the hole. Such packing containers are opened in that the tearing strip with the help of a readily grippable pull-tab or pull-ring is pulled upwards and backwards over the hole, as a result of which the firmly sealed plastic film, covering it from underneath, is stretched and torn off against the cut edge of the hole to expose a corresponding pouring opening through which the contents of the package can be emptied. An opening arrangement of the tearing strip type described here as a rule is easy to open, but the facility of allowing the contents to be poured in a desired coherent and well-directed jet is impaired by the fact that the plastic film adhering to the inside of the package often produces a somewhat uneven or frayed tearing edge around the pouring opening. One of the causes of the uneven tearing edge is that it is difficult to carry out the seal between the tearing strip and the plastic film in the area closest to the cut edge of the opening which means that as the outer tearing strip is pulled away the plastic film is stretched and breaks sooner within this poorly sealed region than against the cut edge of the opening. A further problem with this type of opening arrangement is that the plastic film torn away within the opening region exposes the cut edge of the opening so that the contents come into contact with, and are absorbed by, it during the pouring. Furthermore, EP-A-0 236 556 describes another opening device, projections of it are folded over and attached to the edge of the hole in the wall of the container. It is an object of the present invention to facilitate the production and handling of the opening arrangement on a packing container. The invention is characterized in the characterizing part of the new claim 1. On the one hand, a thermoplstic inner coating is used in the (upper) end wall of the container independent whether or not it is formed by using metal. On the other hand, the free end of the projection is folded over round the cut edge. Finally, the free end is sealed to said thermoplastic inner coating in a liquid-tight and mechanically strong sealing joint round the whole opening contour of the whole. The invention is contrary to the prior art arrangement because the latter one needs to be pressed into the hole in the metallic end wall of the container after rupturing of the metal closure so that the sealing is effected by just the forces of the material of the opening arrangement against the sharp metallic contour of the hole. Therefore, the sealing is often very insufficient. The invention, however, can be combined with the opening arrangement from the very beginning. That means that the opening arrangement is sealed with the container before or after filling of the filling goods into the container but before the final closing and shipping of the containers. Therefore, there is no risk of insufficient sealing and there is no necessity of at first removing a metallic part from the end wall of the container in order to insert the complete opening arrangement afterwards. From a point of view of the consumer it is often a wish to allow reclosure of an opened, partly emptied, packing container so as to provide at least a certain protection to the contents of the container until the next occasion of emptying. This wish too is met with the help of the opening arrangement proposed in accordance with the invention, in that in accordance with a further embodiment developed it has been given the further characteristic that the main part of the other end of the strip, which preferably is connected with the said one strip end by means of a flexible intermediate piece serving as a bending hinge, is of a cup-shaped design open towards the top with a plane base and upright unbroken side wall, the side wall being shaped and dimensioned so that, fitting accurately the boundary edge of the pouring opening, it can be pressed down into, and retained in, this opening. A secure reclosure is obtained in accordance with the invention by providing the side wall with an outer, unbroken, compressible bulge which is adapted so that on reclosure it can engage in a corresponding shoulder, directed radially inwards, formed in the projection accomodated in the hole in order to retain the cup-shaped strip end in the restored, pressed-down reclosure position. To improve further the pouring properties of a packing container which has been provided with an opening arrangement in accordance with the invention, the strip appropriately may have a pouring edge designed as a prolongation of the one end of the strip in the intended pouring direction which extends up to, or projects slightly out over, a boundary edge of the container wall provided with the hole. In accordance with a very simple embodiment of the invention, but one which functions well in practice, the material strip can consist appropriately of a coherent (injection-moulded) piece of polythene or a similar weldable or heat-sealable thermoplastic material, e. g. polypropylene. Such an integral plastic strip is both easy to manufacture and to apply and can be fabricated, moreover, in large series production at low costs of manufacture and material. In the following the invention will be described and explained in detail with special reference to the attached drawings wherein Figure 1 shows schematically a sectional view of a part of a closed packing container provided with an opening arrangement in acordance with the invention, Figure 2 shows the same sectional view as Figure 1 with the opening arrangement in opened position, and Figure 3 finally shows a corresponding sectional view with the opening arrangement in reclosed position. Figure 1 -3 thus show a sectional view of an upper corner region of a packing container 1 provided with an opening arrangement in accordance with the invention. The container 1, for example, may be a conventional parallelepipedic, so-called non-returnable, package with four vertical side walls 2 situated oppositely in pairs and an upper and a lower substantially plane end wall 3 connected to the side walls, whereof only the top one is shown in the drawing. A package of this kind is manufactured in accordance with known technique in that a web of a laminated material, customarily thermoplastic-coated paper, is converted first to a tube by joining together both axial edges of the web in a longitudinal overlap joint. The tube is filled with the intended contents and is divided into closed, cushion-shaped packing units through repeated flattenings and transverse sealings of the tube at right angles to the longitudinal axis of the tube. The packing units subsequently are separated from one another by means of cuts in the transverse seals and are given a desired parallelepipedic end shape through a further forming and sealing operation during which double-walled, triangular corner lugs of the packing units are folded in against, and sealed to, the outside of packages. The package 1 has a hole 4 punched out in its upper end wall 3, located at one of the corner regions of the end wall adjoining a boundary edge 5 between the end wall and a neighbouring side wall 2. The shape and size of the hole 4 are not critical according to the invention, but may vary in each instance to suit the actual contents of the package. The hole 4 is covered from above by the opening arrangement in accordance with the invention which in the embodiment shown is constituted of a material strip 6 attached to the outside of the container wall 3 whose two ends 6a and 6b respectively are connected with one another by a flexible intermediate piece 6c serving as a bending hinge. The strip 6 preferably is made as a coherent, injection-moulded thermoplastic piece of polyethylene or a heat-sealable plastic material similar to the thermo - plastic coatings of the packing material. As is evident from the Figures, the one end 6a of the strip has a downwards directed projection 7 accomodated in the hole 4 of a shape and dimensioning which is such that it connects with a good fit to the cut edge of the hole. The free end 7a of the projection 7 is folded round the said cut edge and is sealed to the inside of the container wall 3 round the whole contour of the hole in a liquid-tight and mechanically strong sealing joint to ensure a good fastening of the strip 6 to the container wall. The projection 7, moreover, has a shoulder 8 directed radially inwards and delimits a portion 9 of reduced material thickness, situated wholly within the region of the hole, which is adapted so that it can be torn away to form a corresponding pouring opening through which the contents of the package are made accessible. This thickness-reduced material portion 9 preferably is designed so that the pouring opening formed is given an optimum shape for the particular contents. As is evident, the strip 6 has a pouring edge 10 in the shape of a prolongation of the one end 6a of the strip in the intended pouring direction of the contents, which extends up to, or projects slightly out over, the boundary edge 5 of the container wall 3 provided with the hole to facilitate the pouring out of the contents of the package and thereby improve the pouring properties of the package, which are improved further in that the strip 6 is provided with vertical lateral edges or banks 11 along the longitudinal edges of the one end 6a. The lateral edges or banks 11, which extend up to the outermost end of the pouring edge, help to guide and collect the contents poured out to a concentrated flow towards the pouring edge from where they leave the package in a drip-free, well-directed, coherent jet. The other end 6b of the strip, which is bent forwards over the hole 4, is of a substantially cup-shaped design with a base 12 and surrounding upright side walls 13. The base is bent to rest flat against the thickness-reduced material portion of the one end of the strip and is sealed to this portion along a region A which follows the whole boundary line of the thickness-reduced portion. At the other end 6b of the strip there is, furthermore a grip-ring 14 projecting from the base 12 and situated almost completely within the region of the side walls 13 of the cup-shaped formation which is adapted so as to facilitate a pulling backwards of the second strip end 6b on opening of the package 1. To make possible a reclosure of the package 1 the cup-shaped strip end 6b is shaped and dimensioned so that it can be pressed down into, and with a good fit against, the remaining tearing edge 15 after the torn-away, thickness-reduced material portion 9 is retained in the torn-up pouring opening. To improve further the retention of the strip end thus pressed down, the side walls 13 are provided with an outer, all-around, compressible bulge 16 which is adapted so that it can engage in the shoulder 8 directed radially inwards in the projection 7 directed downwards of the underlying strip end 6a. The strip 6 finally is provided with an L-shaped section 17 projecting from the top edge of the front wall 13 for the protection of the pouring edge 10 on the underlying strip end 6a. The profile 17 is dimensioned so that the front leg 17a directed downwards is able to surround an outer end of the pouring edge 10 when the cup-shaped strip end 6b is pressed down into the pouring opening on reclosing of the package. When the package shown in Figure 1 in closed position is to be opened, the grip-ring 14 at the forwards bent strip end 6b is grasped and pulled backwards and upwards to the position shown in Figure 2, whereby the thickness-reduced material portion 9 is torn up over the hole 4 at the underlying strip end 6a along its boundary line and follows along adhering to the base 12 of the strip end pulled backwards so as to expose a corresponding access opening for the contents of the package. When the opened package is to be reclosed, the backwards-bent strip end 6b is bent forwards and is pressed down into the pouring opening, the outer, all-around bulge 16 on the side walls 13 of the cup-shaped formation engaging in the shoulder 8 directed radially inwards in the projection 7 and retains the strip end pressed downwards in the reclosure position shown in Figure 3.

Claims: Opening arrangement on a packing container comprising a hole (4) punched out in a wall (3) of the container (1) which is covered from above by a flexible material strip (6) attached to the outside to the container wall whose one end (6a) has an opening part situated wholly within the region of the hole (4) capable of being torn away, wherein the strip (6) of thermoplastic material is firmly connected to the container wall (3) by means of a projection (7) extending from the underside of the strip (6) and accomodated in the hole, wherein the other end (6b) of the strip (6) is bent over the hole (4) and connected to said one end (6a) of the strip within a connecting region which comprises at least a part of the underlying opening part capable of being torn away, and wherein the strip (6) is provided with a readily grippable pull-ring (14) or pull-tab to facilitate a pulling backwards of the other end (6b) of the strip (6) thus bent whilst tearing away at the same time the accompanying opening part to expose a corresponding pouring opening when the container is opened, characterized in that the free end (7a) of said projection (7) is folded over round the cut edge of the hole (4) and sealed to the thermoplastic inner coating of the upper end wall (3) of the container (1) in a liquid-tight and mechanically strong sealing joint round the whole opening contour of the hole (4) and that the openable part of said one end (6a) of the strip (6) comprises a portion (9) of reduced material thickness surrounded by the extending projection (7) and sealed to said other end (6b) of said strip (6) along a region (A) which follows the whole boundary line of said thickness-reduced portion (9). Opening arrangement in accordance with claim 1, characterized in that said ends (6a and 6b) are joined to one another by a flexible intermediate piece (6c) serving as a bending hinge. Opening arrangement in accordance with anyone of the preceding claims, characterized in that the main part of other end (6b) of the strip is of a cup-shaped design open towards the top with a plane base (12) and upright, unbroken side wall (13), fitting accurately the boundary edge of the torn up hole (4) and capable of being pressed down into said hole (4). Opening arrangement in accordance with claim 3, characterized in that the said side wall (13) is provided with an outer, unbroken, compressible bulge (16) which is adapted so that on reclosure of the hole (4) it engages in a corresponding shoulder (8) formed in the projection (7) accomodated in the hole (4) in order to retain the cup-shaped other end (6b) in the pressed-down reclosure position. Opening arrangement in accordance with anyone of the preceding claims, characterized in that a pouring edge (10) is formed as a prolongation of the one end (6a) in the intended pouring direction, which extends up to or projects slightly over a boundary line (5) of the container wall (3).

Inventors: CARLSSON HANS, JACOBSSON KENT, CARLSSON, HANS, JACOBSSON, KENT
Applicants: TETRA LAVAL HOLDINGS & FINANCE, TETRA LAVAL HOLDINGS & FINANCE S.A.
Application year: 1989
Main classification: B65D17
IPC codes: B65D5, B65D17