A CLOSURE DEVICE FOR A PACKAGING CONTAINER

Abstract: An easy openable closure device for a packaging container, comprising an outer layer (11), for instance injection moulded of plastics, and an inner layer possibly comprising several sublayers and such that it gives the closure device a specific characteristics as to for instance welding possibilities, gas barrier and light barrier. A first tearing denotation (20) is arranged in the outer layer and merges into a second tearing denotation (15) under a tan­ gentially acute angle, said second denotation extending circum­ ferentially around the closure device. At both sides of the circumferential tearing denotation (15), the inner layer (12) is sealed to or connected to the outer layer (11). In the outer layer there is arranged an element (17) having a portion (18) for penetrating the first tearing denotation (20) in the outer layer inside the said sealing region (16, 16′). The strength of the second tearing denotation (15) is lower than the sealing strength between the layers and the latter strength is higher than the tearing strength of the inner layer.

Description: The present invention relates to a closure device for a packaging container according to the preamble of claim 1. Such a closure device is known from, for example, CH-A-404429. The state of the art comprises a number of easy openable covers or closures, also covers where the outer layer is a protective, relatively thick plastics layer and the inner layer a metal layer or a corresponding gas and vapour tight layer, for instance an aluminum foil or a layer of high barrier plastics. Said known structures do also comprise a multitude of grip devices and different sorts of tearing denotations. In that case where the outer layer consists of plastics, however, known easy openable structures generally have the drawback that the manufacturing procedure is a two step procedure, for instance a two step injection moulding operation. This means some sort of later mounting or a complex mould arrangement. The opening procedure of known covers may include a simultaneous penetration of outer and inner layers, but the manufacturing procedure and the known structural measures often involve a very difficult balance act, which unfortunately may result in an end product, which does not meet high demands on a reliable opening possibility. In other cases the opening of the closure is a two step procedure, where the protective outer layer is opened first and the inner layer, generally called the membrane, thereafter is punctured. The aforementioned CH-A-404429 describes an end closure, the opening of which is a one-step procedure. A disadvantage with the end closure according to CH-A-404429 is, particularly if the package to which it is affixed contains a liquid, that penetration of the outer layer followed by penetration of the inner layer occurs in substantially the same direction of pull of the end closure's tearing element. According to the invention it has been realized that for obtaining the desirable objects, the following requisites are necessary: the opening arrangement shall define a well defined tearing direction, the outer and inner layers shall be opened together but sequentially such that the outer layer is first broken through, whereafter the inner layer is penetrated, and additionally the outer layer, or the mechanically reinforcing layer, shall be manufactured in one single step, for instance by injection moulding. One object of the invention is to give a multilayer cover, or a cover of the "composite cover" -type, reliable /easy opening characteristics without unduly excluding a rational one step cover injection moulding manufacturing technique. Another object is to provide a closure structure allowing a variety of material combinations for the composite closure without deteriorating the easy opening possibilities. Additionally, a still further object is to provide a structure offering alternatives for the placement of gripping devices and tearing denotations. These object are attained by a closure device according to claim 1. Preferred embodiments of the present invention are given in the dependent claims. The invention will now be exemplified by reference to the accompanying drawing, where Fig. 1 in a view from above schematically shows one embodiment of a closure device according to the invention, Fig. 2 in a section view shows the device in Fig. 1. The closure device 10 in Fig. 1 is of the "full panel opening type" intended for a packaging container and comprises an outer configuration 11, in the present case consisting of a mouldable or injection mouldable plastics or corresponding, which forms the mechanically reinforcing and resistant part of the cover. Of course, the element 11 may also comprise further elements or layers. Along the entire inside of the outer element or layer 11 there is arranged an inner layer 12, which also may comprise several layers, and which is a relatively thin and flexible layer, the main object of which is to give the closure structure specific characteristics, for instance welding characteristics, gas barrier and light barrier. In the embodiment shown the cover has a generally plane panel 13 and a rim or collar 14 extending around said panel arranged for attachment to the casing of a packaging container (not shown). A short distance inside the rim 14 there is arranged a circumferential weakening or tearing denotation 15 in the outer layer 11. This tearing denotation is such that flowing out of material, for instance injection moulding may take place from a centrally placed ingot. Of course, the flow of material may be the reverse if necessary. The inner layer 12, or the so called membrane, which may comprise for instance aluminum foil, metallized plastics film or a gas barrier laminate, is sealed to the outside of the rim 14 in a circumferential region 16. This sealing region 16 merges into a welding region 16′, also circumferential, which has a very short radial extension inwards from the weakening 15. Said both welding regions 16, 16′ are located at either sides of a weakening 15 in the outer layer 11, in the present case in the shape of continuously integral welds between the thermoplastic coatings of the layers 12, 11. However, it is obvious that the sealing regions 16, 16′ may be arranged in another manner, for instance as discontinuous joints obtained for instance by a two-component glue or similar. However, it is important that the sealing strength of the sealing region 16, 16′ is higher than the strength of the tearing denotation obtained by the weakening 15 and such that it is higher than the tearing strength of the inner layer. A grip tongue 17 is formed on the outer layer 11 and merges into a reinforcing point 18 adjacent to a pointed region 19 of a second weakening or tearing denotation 20 in the outer layer 11. The tearing denotation 20 is terminated upwards in Fig. 1 by a tearing line 20′ extending arbitrarily, but not allowed to extend up to the tearing denotation or weakening 15. Towards the other direction in Fig. 1, however, the tearing denotation 20′ merges into the tearing denotation 15 under a tangentially acute angle. By this measure the tearing denotation is defined uniquely and the breaking through operation of the outer and inner layer composite structure is facilitated. It should be noted that the point 19 is located inside the tearing denotation 15 and in that region of the inner layer 12 which is unsealed or has no adhesive bond to the outer layer 11, meaning that when the tongue 17 is gripped and lifted, the outer layer is first broken through at the point 19, and thereafter the tearing follows the tearing denotation 20′ by a corresponding manoeuvring of the grip tongue. Finally the tearing merges into the tearing denotation 15, which then is penetrated, without delamination of the inner and outer layers but with penetration of the inner layer. Within the scope of the accompanying claims there are, of course, other possibilities than the one just identified.

Claims: 1. A closure device (10) for a packaging container, said closure device, comprising a panel for removably closing said packaging container, said panel having an outer layer (11) and an inner layer (12), said outer layer and inner layer being separable from one another in a separable region so that a portion of said outer layer can be penetrated and separated from said inner layer without opening the packaging container, and said outer layer and inner layer being connected in an openable region (16, 16′), the thus formed connection having a certain sealing strength; a first tearing denotation (20) in the outer layer (11) to facilitate the separation of a portion of said outer layer from said inner layer in said separable region without opening the packaging container; a tearing element (17) integral with said outer layer (11) for initiating the tearing of said first tearing denotation (20); a circumferential tearing denotation (15) in said openable region (16, 16′), said first tearing denotation (20) being connected to said circumferential tearing denotation for initiating the tearing of said circumferential tearing denotation, whereby the strength of said circumferential tearing denotation (15) is lower than said sealing strength between the layers, with the latter strength being higher than the strength of the inner layer (12), characterized in that said first tearing denotation (20) is provided with a pointed region (19) along its length remote from said connection to said circumferential tearing denotation (15), wherein said pointed region (19) lies adjacent to a reinforcing point (18) integral with said outer layer (11) and tearing element (17), which reinforcing point and tearing element (17) are flanked by said first tearing denotation (20) extending on both sides from said pointed region (19), whereby upon operation of said tearing element, said outer layer (11) is penetrated at said pointed region (19). 2. A closure device according to claim 1, characterized in that the first tearing denotation (20) merges into the circumferential tearing denotation (15) under a tangentially acute angle. 3. A closure device according to claim 2, characterized in that the circumferential tearing denotation (15) is arranged close to a rim (14) arranged around the circumference of the closure device for defining a full panel opening. 4. A closure device according to any of the preceeding claims, characterized in that said reinforcing point (18) is formed by a region by material thicker than the remainder of said outer layer (11). 5. A closure device according to any of the preceeding claims, characterized in that said tearing element (17) is in the form of a grip tongue whose grippable portion stands proud of said outer layer (11).

Inventors: LARSSON, LENNART
Applicants: AB AKERLUND & RAUSING
Application year: 1988
Main classification: B65D17
IPC codes: B65B7, B65D41, B65D51, B65D17