EP0193477B1 - Paper bag with a bottom provided with a filling valve - Google Patents

Description

The present invention relates to a paper bag, a bottom of which is equipped with a filling valve.

When they are intended for the packaging of pulverulent products, certain paper bags produced from a tubular element, the two ends of which are closed by folding and gluing with a view to achieving a crossed bottom or a square bottom, have a bottom comprising an orifice allowing the introduction, into the folded structure, of a bagging cannula ensuring the transport of the product towards the interior of the bag.

The design of the bottom allows, after removal of the cannula, the automatic closing of the orifice under the effect of the pressure of the product contained in the bag. This structure is obtained by adding to the interior of the bottom of a specific shaped element having a transverse slot, and called "valve •.

Whatever the sophistication of the valve element, it is never possible to obtain a perfect seal of the filling orifice.

Furthermore, the folding of the bottom, on the valve side, ensures, by its structure, the formation of folds delimiting unwanted conduits allowing the leakage of material intended to fill the bag, in particular in the folding opposite to the filling orifice , during the projection of the material during bagging.

To avoid these leaks called "chimney", it is known to add to the bottom of the bag an additional paper butterfly called "targette" stuck on the four flaps of the bottom, which allows to cover folds and remove defects by leaks.

This technique requires the separate production of the constituent elements of the valve and the valve respectively, their positioning and their fixing independently of one another in the bottom of the bag, which constitutes long and expensive operations, and which increases the thickness of the bottom of the bag.

The present invention aims to remedy these drawbacks.

To this end, in the bag which it concerns, of the type produced from a tubular element and in which at least one of the bottoms is constituted by four identical flaps two by two, and folded in pairs towards the central part from the bottom, this bottom is equipped with a valve element, made from a sheet of paper or a cardboard plate of length greater than the distance between the two flaps of the first pair of flaps located on the side of the interior of the bag and of width greater than twice the distance between the two fold lines of the two flaps of the second pair of flaps, this element being folded back on itself and closed by gluing to form a flat tube whose one of the ends is closed, this tube being fixed by gluing on the outside face of the two interior flaps, and on the inside face of the two outside flaps, the wall of the tube situated on the side of the interior flaps comprising, in its zone situated between them ci, a transverse slot.

To fill the bag, it is possible to introduce a cannula through the open end of the tubular element, which results in the opening of the transverse slot, allowing the passage of the products through it. inside the bag.

When the bag is full, and the cannula is withdrawn, the slot closes and the tubular member flattens under the effect of the pressure of the product. The filling valve function is perfectly fulfilled, as is the targette function, since the tubular element being glued to the four flaps prevents the formation of any chimney likely to lead to the outside.

Advantageously, the face of the tubular element comprising the longitudinal closing edge thereof is located on the side of the outer flaps of the bag.

This structure facilitates the production of the valve and in particular the provision of the filling slot in the face of. the tubular element having no continuity solution.

According to another characteristic of the invention, the facing walls of the tubular element are also secured to one another by gluing along a transverse line located near the filling slot, on the side thereof opposite at the insertion side of the filling cannula in the tubular element.

This arrangement avoids, during filling, the passage and agglomeration of pulverulent products in the closed end of the tubular element.

According to one possibility, the transverse bonding line has at least one interruption zone which allows, during filling, the evacuation of air contained in the bag, which has previously passed through the paper bottom thereof.

Advantageously, the open end of the tubular element comprises, over its entire periphery, a return towards the interior. This return acts as a safety valve preventing the possible outflow of products which could not have been retained by the valve.

To favor this sealing aspect, the fold delimited by the peripheral return serves as a housing for a sheet of flexible synthetic material, projecting inside the tubular element in the direction of the slot. When the filling cannula is withdrawn, the plastic sheet folds, forming a barrier inside the tubular element.

According to a variant, the fold delimited by the peripheral return (23) serves as a housing for a strip of foam (25) which is very sparse, of high compressibility and instantaneous extensibility, projecting inside the tubular element, towards the slit.

• Figure 1 est une vue en perspective d'un sac en papier ;
• Figure 2 est une vue en perspective du fond de ce sac en cours de remplissage ;
• Figure 3 est une vue à plat du fond du sac avant montage de la valve ;
• Figure 4 est une vue à plat du fond du sac en cours de montage de la valve ;
• Figure 5 est une vue en coupe longitudinale du fond, en cours de remplissage du sac, selon la ligne V-V de figure 2 ;
• Figures 6 et 7 sont deux vues en coupe longitudinale de deux variantes de ce fond après remplissage du sac.

In any case, the invention will be clearly understood with the aid of the description which follows with reference to the appended schematic drawing showing, by way of nonlimiting examples, two embodiments of this valve:

• Figure 1 is a perspective view of a paper bag;
• Figure 2 is a perspective view of the bottom of this bag being filled;
• Figure 3 is a flat view of the bottom of the bag before mounting the valve;
• Figure 4 is a flat view of the bottom of the bag during assembly of the valve;
• Figure 5 is a longitudinal sectional view of the bottom, during filling of the bag, along the line VV of Figure 2;
• Figures 6 and 7 are two views in longitudinal section of two variants of this bottom after filling the bag.

FIG. 1 represents a paper bag (2) produced from a tubular element, one end (3) of which is closed, is equipped with a handle (4) and the other end of which is closed off by a square bottom (5 ). This square bottom is obtained, in a known manner, by providing four identical flaps two by two, namely two interior flaps (6) and two exterior flaps (7). The two inner flaps (6) are spaced from one another and provide an access (8) inside the bag, while the two outer flaps (7) come, in the closed position, overlapping the one from the other, as shown in the drawing.

As shown in Figure 3, the bottom is equipped with an element (9) of paper or cardboard, the side facing the inside of the packaging is shown in the drawing. It should be noted that in FIGS. 3 and 4, the areas comprising dotted lines are glued.

The element (9) has a length greater than the distance between the facing edges of the two flaps (6), and a width greater than twice the distance between the two fold lines (10) of the two outer flaps (7) .

The element (9) comprises two folds (12, 13) corresponding to the folds (10) of the flaps (7), and, in the central part (14), that is to say in the area between the folds (13) a transverse slot (15). The glued areas ensure the fixing of the element (9) on the four flaps (6, 7) of the bottom of the bag.

Figure 4 shows the opposite face of the element (9), that is to say that located on the outside.

When the bag is closed, the element (9) folds back to form a tubular element, and the glued side part (16) covers the edge of the other side part (17).

In addition, glues (18) and (19) formed transversely on the central part of the element (9) ensure the closure of one end of the tubular element and a transverse closure of the latter in its central part, on the side of the slot (15) opposite the open end of the tubular element.

The area (19) may include certain interruptions (20) of glue ensuring the formation of chimneys allowing the escape of air during filling of the bag.

It should be noted that, in the embodiment shown in the drawing, the element (9) is positioned so that its open end corresponds to an edge of the bottom, which facilitates the introduction of a filling cannula (22).

FIG. 5 represents this bottom, seen in longitudinal section after introduction of a filling cannula (22). As can be seen from the drawing, the introduction of the cannula allows filling through the slot (15) without the risk of the product escaping to the outside, or accumulating on the side of the closed end of the element. tubular.

FIG. 6 represents a variant of the element (9) in which the tubular element comprises, on the side of its open end, a return (23) inwards, extending over its entire periphery. In the fold formed by the return (23) is housed a sheet of flexible synthetic material (24) such as polyethylene which extends in the tubular element in the direction of the slot (15). The rim (23) acts as a non-return valve for the pulverulent material which could have accidentally passed through the slit (15) after closing it, and the sheet of synthetic material (24), which crumbles during the withdrawal of the cannula plays the role of a baffle further enhancing the effectiveness of the closure.

In the embodiment shown in FIG. 7, the fold delimited by the rim (23) serves as a housing for a strip (25) of very sparse foam, of high compressibility and instantaneous extensibility, closing off all the conduits may result from folds of the sheets of paper or cardboard constituting the valve, and / or the presence of residual bagged product in the valve.

As is apparent from the above, the invention brings a great improvement to the existing technique by providing a bottom of a paper bag equipped with a single element having both the valve and “targette” functions preventing product flows. outwards, and constituting an internal reinforcement of the bottom sufficient to avoid the presence of an external reinforcement strip, added, of poor aesthetics.

Claims (7)

1. A paper bag, a base of which is equipped with a filling valve, of the type produced from tubular material and in which at least one of the ends consists of four identical flaps in pairs and folded in pairs towards the central portion of the base, characterized in that the base is fitted with a component forming a valve, produced from a piece of paper (9) or a sheet of card of length greater than the distance between the first pair of flaps (6) that are situated on the inside of the bag and of width more than double the distance between the two folding lines (10) of the second pair of flaps (7), this component being folded back on itself and closed by gluing to form a flat tube one of the ends of which is closed, this tube being fixed by gluing to the external face of the two internal flaps (6), and to the internal face of the two external flaps (7), the wall of the tube situated on the side of the internal flaps comprising, in its area situated between the latter, a transverse slot (15).

2. A bag according to Claim 1, characterized in that the face of the tubular component that comprises its longitudinal edge is situated on the side facing the external flaps of the bag.

3. A bag according to one of Claims 1 and 2, characterized in that the facing walls (14, 17) of the tubular component are also joined together by gluing along a transverse line (19) situated near to the filling slot, on the side of the latter opposite to that on which the filling nozzle is introduced into the tubular component.

4. A bag according to Claim 3, characterized in that the transverse gluing line (19) possesses at least one interruption area (20) that, during filling, allows escape of air contained in the bag, which has previously passed through the paper base of the latter.

5. A bag according to any of Claims 1 to 4, . characterized in that the open end of the tubular component comprises a fold-back (23) towards the interior, extending around the whole periphery of the component.

6. A bag according to Claim 5, characterized in that the tuck produced by the peripheral fold-back (23) serves to retain a sheet (24) of flexible synthetic material, that extends within the tubular component in the direction of the slot.

7. A bag according to Claim 5, characterized in that the tuck produced by the peripheral fold-back (23) serves to retain a narrow band of foam (25) of very low density, highly compressible and instantly extensible, that bulges into the interior of the tubular component in the direction of the slot.

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