One-hand quick-opening closure device for sealed bags made of plastic material or paper   

Abstract: A quick-opening closure device for sealed bags is described. The device can be opened and used by one hand, as the mouth of the bag is torn by the compression made by two fingers of a user by bending two juxtaposed sheets.

Sealed bags made of plastic material and paper are used for several packaging processes. The most common contents are sundry small items, small spare parts, technical powders, food powders such as sugar, spices, herbs for infusions, drugs, various small sampling items. The drawbacks in common to all such small packages are the need of using both the hands for tearing their mouth and the particular attention necessary to subsequently empty them in order not to lose their contents, without counting the loss of time for such operations. The solution provided by this invention contemporaneously solves these three drawbacks.

A similar opening system has been already available for a long time on the market and it is the device for opening small purses and the like which were provided with two flexible steel sheets which opened by bending by means of a pressure exerted on their ends by fingers. The device according to the present invention is different than the above mentioned system both as regards the particular shape and the material of the sheets 1 and as regards their specific tearing function during the opening action at the outer border with a sharp corner of the sheets 1 of the bag 2 and as regards the fact of being specifically used for opening sealed bags 2.

FIG. 1 is an hand holding a typical bag 2 according to the present invention which is opened as a consequence of tearing the borders 3 of the mouth due to the compression C exerted on sheets 1 by the forefinger and the thumb. The parallelogram shaped mouth is generated by grooves 5 made within the sheets 1 which weaken the local resisting moment thereof.

FIG. 2 is two pre-bent sheets 1. A top view of two juxtaposed sheets 1 (with the bag in the sealed condition), a top view of two curved sheets 1 (without internal stresses) and a side view with the rectangular section thereof below can be seen.

FIG. 3 is two sheets 1 with a variable thickness (the thickness is greater in the centre). A top view of two juxtaposed sheets 1, two sheets joined by a film 4 at two ends thereof slightly opened and a side view with the trapezoidal section thereof below can be seen.

FIG. 4 is two sheets 1 having each one a groove 5. A top view of the two juxtaposed sheets 5 with their two displaced grooves 5, two just opened sheets with a parallelogram shape and a side view of the inner portions of the two sheets 1 with their two parallelogram sections below can be seen.

FIG. 5 is five types of sections suitable for the proper operation of the invention.

FIG. 6 is a strip portion made of any suitable material 7 upon which two adjoining sheets 1 arranged orthogonally to the length of the strip are glued or welded. The cut lines it and the folding line 1p by 180° can be seen. Edges 6 to be glued or welded are shown too.

FIG. 7 is a strip portion made of any suitable material 7 upon which a series of two parallel sheets 1 is glued or welded, orthogonally to the strip length, which are drawn close to each other and spaced by a distance 2s equal to twice their thickness. Each pair of sheets 1 is spaced from two adjacent ones by a distance equal to twice the length hs of a bag 2. The cut lines It and the folding lines 1p by 180° can be still seen. Edges 6 to be glued are shown too.

FIG. 8 is a strip portion made of any suitable material 7 upon which a series of pairs of parallel sheets 1 are glued or welded along the centre line of the strip, which are drawn close to each other and spaced by a distance 2s equal to twice their thickness. The distance between two adjoining pairs is equal to the width of two edges 6. The cut lines 1t and the folding lines 1p by 180° can be seen. Edges 6 to be glued or welded are shown too. The distance among cuts is equal to the width of the bag 2, while the length of bags is equal to one-half of the strip width.

The principle of this invention is to provide the use of two sheets 1 made of elastic material preferably plastic polymer which are juxtaposed with the bag 2 in the closed condition, even with variable sections along their length direction, each one of them having a length equal to one-half of the circumference of the mouth of the bag 2, and such an height and thickness that lead to a controlled bending moving them apart at their central area and contemporaneously causing the border of the mouth of the bag 2 to be torn when a compression C is exerted on their ends, by two fingers. Such two sheets 1 are generally welded or glued, preferably on the inside of the edge 6 to be opened of the bag 2. Sometimes it can be useful also to apply them on the outside. Moreover, the orthogonal sections along said elastic sheets 1 can be different and such that it is easier to initially mutually moving them apart and moreover, as it will be shown below, the two closed borders of the mouth of the bag 2 can be accurately torn. These actions can be easily carried out by a simple compression C of the two sheets 1 acting throughout their length for example between the thumb and the forefinger. The same hand used for opening them, obviously will be used afterwards for pouring the contents of the bag 2 when necessary.

In order to allow the two flexible sheets 1 to bend while moving apart tearing the mouth of the bag, their pre-bending, if any, and the sections orthogonal to and along their maximum dimension (their length) can have different shapes and anyway such shapes in order to create outwardly directed components which are perpendicular to the compression force C of fingers. According to the present invention there are at least three basic methods for achieving such result of the sheets 1 in question, which obviously comprise also their conceptually equivalent variants, which are listed below: 1) Making the two sheets 1 (FIG. 2) such to be pre-bent lengthwise, such that when their concave portions match each other upon the closure of the bag, their inner structure is under a bending tension condition which, in combination with the compression force C exerted by fingers, which can be applied upon the opening, allow said two flexible sheets 1 to outwardly bend. In this case the orthogonal sections of said elastic sheets 1 can have any mechanically valid sections and they can also be all equal to each other. At least one of the two upper borders of said sheets has a sharp corner in order to facilitate the tearing of the mouth. One of the two faces rests on a cylindrical surface such that the edges 6 of the bag 2 are glued or welded more easily. 2) Making the two sheets 1 (FIG. 3) with a flat face and with the central area thicker than those at distal ends. Thus upon bending the neutral plane is farther from their common contact flat surface at the centre than at the two distal ends. The optimization is achieved with sections whose thickness decreases from the centre to the two distal ends. Different types of deformed configurations can be obtained by suitably changing the moments of inertia (for example I=bh3/12 in the case of rectangular sections) along the sheets. When the sheets are subjected to a compression C an initial moment M is generated in the several sections which is equal to the compression force C multiplied by one half of the thickness of the section under examination, that is C×½ s. Such initial moment generates always an outwardly bending and the local radius R of the deformed configuration is equal to E×I/M everywhere where E is the modulus of elasticity of the material and I is the above mentioned moment of inertia. 3) Making the two sheets 1 (FIG. 4) preferably with a constant, or also non constant section, whose inner faces to be matched with the bag in the closed condition, have two constant section grooves 5 perpendicular to the length of said sheets 1 which locally weaken the moment of resistance to bending (for example, in the case of rectangular sections said moment of resistance, as known, is b. h2/6). Said two grooves 5, that is one for each sheet 1, are mutually arranged symmetrically than their common longitudinal centre such that, when the two fingers exert the compression C, they will get a predetermined deformed configuration with two broken lines each one having a parallelogram shape. Such arrangement initially facilitates the tearing of the border of the bag mouth at the two grooves 5.

In order to make this operation according to the three arrangements and relevant variants described above easier, the two sheets 1 can be already joined together, making only one sheet, by two of their distal ends by a short thin connection film 4. Thus they can be easily juxtaposed when they are folded one against the other by 180° together with the strip upon which they are glued or welded. Sheets can be easily produced, depending on the shape of sections, both by molding and by extrusion with a subsequent cut 1tparallel to their length. The cut 1t can also be made with an inclination in order to generate a sharp corner with an acute angle.

The simplest arrangement of such quick-opening on bags 2 to be filled (FIG. 6) is to prepare a strip made of paper or plastic material upon which two flexible sheets 1 are applied, perpendicularly to the strip length and at the same distance one to the other, one after another or joined 4 together by their ends. There are different application methods but the simplest ones are glueing in the case of paper and welding in the case of plastic material. Therefore the strip can be folded 1p by 180° along its longitudinal centre line and then glued or welded along its two free side edges. Then the two sheets 1 are juxtaposed one upon the other, and in case they are glued by a Stick-no-stick adhesive.

Finally the strip folded in this manner is cut 1t at the desired length of the bags and then, or contemporaneously with the cutting 1t it is welded or glued just above the two sheets 1 such that the glueing or welding contemporaneously make the closures of the bottom and mouth of each bag 2. The two free side edges 6 therefore can be glued or welded, after being in case laterally filled, by conventional filling machines in use on the market. Such solution is also suitable for bags 2 that can be manually filled when the two juxtaposed sheets 1 are kept adherent each other by stick-no-stick adhesive. In this case the bending does not tear the paper or the plastic material but it unglues the two sheets 1 that will be glued again upon the release of the compression C.

A second process (FIG. 7) for making bags 2 giving the same results is to apply two sheets 1 which are adjoining or already joined together 4, such as in claim 5, followed by other two equal adjoining sheets 1 spaced from the first two by a distance 2s that is equal to twice their thickness which are arranged orthogonally to a strip whose width is twice the width of the bag plus two edges 6 intended for the lateral glueing or welding. The two double sheets 1 along the strip are spaced from the following two by a distance equal to twice the length of the bag plus two edges 6 for the final glueing or welding of the bag bottom. In this process the strip is cut 1t and welded or glued parallely to the sheets 1 at one-half the distance between two subsequent double sheets 1. Strip portions obtained in this way are folded 1p by 180° between the two double adjoining sheets 1 thus the latter are juxtaposed. Therefore the side edges 6 are glued or welded. The bottom aperture will be then glued or welded after filling the bag 2. This solution is suitable for sealed bags 2 and they are opened always by a tearing action.

A third process (FIG. 8) provides to apply at the

centre of the strip, whose width is twice the length of the bags 2 plus two edges 6 to be welded or glued, plus twice the thickness 2s of sheets 1, and along all its length two parallel rows of adjoining sheets 1 spaced apart by a width 2s that is twice the thickness of the sheets 1. The two double pairs of sheets 1 are spaced one another lengthwise of the strip by a distance that is twice an edge 6 for the lateral glueing or welding. Then the strip is folded 1p by 180° along its centre line that is at the same distance between the two rows of pairs of sheets 1 and therefore it is cut 1t, orthogonally to the strip length, at the same distance between the relevant ends of two double pairs of adjoining sheets 1. Such strip portions then can be welded or glued at the two sides 6 of the bag and then filled and sealed at the bottom of the bag 2. This process easily lends itself to line automation. Even in this case the manual opening occurs by a tearing action.

Obviously these three handcrafted or partially handcrafted methods for producing bags 2 that can be filled and welded or glued after filling them can be easily transformed into automatically mechanized processes for producing in series and at a high speed sealed bags 2 which are filled during the process itself.

Generally in these cases bags 2 are used for containing medicinal powders or food powders such as for example bags containing sugar doses intended for bars. Thus the number of packages and the cost of their contents will define the packaging method to be selected, which is more or less automatized depending on numerical, commercial and economic requirements. In the market several methods are available for automatically filling and producing bags and any of said known processes can be easily modified only for applying the two flexible sheets 1 to each bag 2 which are the essential elements of the present invention, together with their peculiar use.

In order to quickly open a bag 2 according to this invention the bag 2 needs only to be taken by two fingers, preferably the forefinger and the thumb, placing the two fingertips on the distal ends of the two juxtaposed flexible sheets 1 of the closed bag 2. By means of a simple compression C of said two fingers the two sheets 1 will bend outwardly tearing the edge 6 made of paper or plastic material glued or welded at or near the upper border with a sharp corner of the two sheets 1. The glued or welded closure will be carried out such to exert the proper resistance to tearing and therefore to the compression C made by the two fingers. In practice, for the opening to be within everyone\'s reach, such force will be equal to about the force necessary for two fingers to grasp a coffee cup by its handle. Thus the closure will be easy to be opened but it will be sufficiently strong and safe. In order to achieve such effect among the three types of sheets 1 the solution n.3 is the one that best suits limited compression forces since corners of sheets (1) taking a parallelepiped shaped deformed configuration have two locations, at the two grooves 5, wherein the pressure increases very quickly and where the tearing inevitably begins.

Once the bag (2) is opened the same two fingers will cause the contents to be poured when necessary without releasing the hold.

The equidistant displacement of the two grooves 5 on one part and on the other part from the centre of the two sheets 1 allows the quick-opening assembly to have a necessary stiffness thus avoiding the closure to be unintentionally bent on one side.