EP1858769B1 - Paper sack - Google Patents

Abstract

The invention relates to a paper sack comprising an overlapping film for fine-grained bulk material such as cement, plaster, granulate, animal feed or similar. Said sack comprises a base (2), for example a cross-bottom base and an upper section (3), which lies opposite the base (2) and is equipped with a valve hose (13) for filling the paper sack (1). The paper sack (1) is configured from an inner layer of paper and an outer layer of paper or paper composite, between which a barrier layer comprising two essentially parallel edges (8, 10) running from the base (2) to the upper section (3) is sandwiched. The sack is characterised in that the barrier layer or layers is or are fixed to the inner layer or the outer layer along one edge (8) by means of an adhesive line (7) and that the other free edge (10) overlaps said fixed edge (8).

Description

The invention relates to a paper bag with film overlap for fine-grained bulk material such as cement, gypsum, granules, animal feed or the like, with a bottom, for example a cross bottom, and with a top opposite the bottom, in which a valve tube for filling the paper bag is arranged, wherein the paper bag is formed of an inner layer of paper and an outer layer of paper, between which at least one plastic film lies ( US Pat. No. 5,493,844 ).

Such paper bags are well known and are widely used in commerce. The usual sizes are 5 kg, 10 kg or 25 kg.

For filling a valve tube is provided, which is incorporated in the upper part and is plugged for filling on a filler neck. The known valve bags consist of an inner and an outer layer of paper, between which a plastic film is inserted as a water vapor barrier layer. The plastic film is not connected at the edges, but only loosely overlapped inserted to allow air to escape during filling of the hose. The overlapping edges of the middle plastic layer thus run parallel to the side edges of the paper bag and thus extend from the bottom to the top.

• Die Durchlaufzeiten zum Befüllen der Säcke erhöhen sich.
• Da sich während der Befüllung noch Luft im Sack befindet, kann nicht die gewollte Füllgutmenge in den Sack eingefüllt werden, so dass eine exakte Festlegung des Einfüllgewichts nicht möglich ist.
• Durch das Aufblähen der Säcke mit Luft entsteht ein Überdruck im Sack, der sich beim Abnehmen des Sackes vom Füllstutzen durch das Ventil entlädt. Dabei wird auch ein Teil des Füllguts aus dem Sack ausgetrieben, was zu Verschmutzungen führt.
• Durch die schlechte Entlüftung blähen sich die Säcke mit Luft auf. Da sie nach dem Befüllen aber auf der Überlappung liegen, kann keine Luft mehr entweichen und die Säcke sind unförmig, was eine optimale Palettierung wesentlich beeinträchtigt.

A disadvantage has been found that an optimal filling of the paper bags is not possible because the venting of the bags is not sufficient. After filling the bags but no air can escape, since the bags are then with the entire weight of the product on the overlap and this "close". This results in the following problems:

• The throughput times for filling the bags increase.
• Since there is still air in the bag during filling, the desired amount of product can not be filled into the bag, so that an exact determination of the filling weight is not possible.
• By inflating the bags with air creates an overpressure in the bag, which discharges when removing the bag from the filler neck through the valve. In this case, a part of the contents is expelled from the bag, which leads to contamination.
• Due to the poor ventilation, the bags inflate with air. However, since they lie on the overlap after filling, no air can escape and the bags are bulky, which significantly impairs optimal palletizing.

The object of the invention is therefore to provide a paper bag with improved water vapor density without worsening the venting of the bags.

To solve this problem, the characterizing features of claim 1 in conjunction with the preamble.

The core of the invention is thus to glue an edge of the barrier layer with the inner layer or the outer layer of the paper bag in the known simple overlap. This has surprisingly meant that the venting of the bags has improved by 100% compared to the simple film overlap.

In a preferred embodiment of the invention, two or more barrier layers of sheet-like material are provided which each bonded in the region of an edge with the inner layer or the outer layer, while each free other edge overlaps an underlying barrier layer.

After the sacks have been filled, air can continue to escape in this embodiment, since the sacks with the weight of the product lie only on an overlap and "close" them. On the other overlap, however, no pressure is exerted by the weight of the contents.

• Die Durchlaufzeiten zum Befüllen der Säcke verringern sich.
• Durch die verbesserte Entlüftung befindet sich weniger Luft im Sack, so dass die gewollte Füllgutmenge in den Sack gefüllt werden kann. Dadurch ist eine genauere Festlegung des Einfüllgewichts möglich.
• Da die Säcke nicht mehr so aufgebläht sind, herrscht auch kein Überdruck im Sack. Beim Abwurf des Sackes vom Abfüllstutzen entweicht also kein Füllgut und es treten keine damit verbundenen Verschmutzungen auf.
• Durch die verbesserte Entlüftung sind die Säcke nicht mehr so aufgebläht. Außerdem kann nach der Befüllung weiterhin Luft durch die zweite Überlappung entweichen, so dass die Säcke ihre eigentliche Form annehmen können und eine gute Palettierung möglich ist.
• Die Sperrschicht braucht gar nicht oder kann deutlich geringer perforiert werden; damit erhöht sich der Schutz gegen Feuchtigkeitsveränderungen des Füllguts, d.h. die Produkthaltbarkeit wird deutlich verlängert.

The following improvements can be achieved by the paper bag according to the invention:

• The throughput times for filling the bags are reduced.
• Due to the improved ventilation there is less air in the bag, so that the desired amount of filling material can be filled into the bag. As a result, a more precise definition of the filling weight is possible.
• Since the bags are not so bloated, there is no overpressure in the bag. When the bag is dropped from the filling nozzle, no filling material escapes and no soiling occurs.
• Due to the improved ventilation, the bags are no longer so bloated. In addition, after the filling, air can continue to escape through the second overlap, so that the sacks can assume their actual shape and good palletizing is possible.
• The barrier layer does not need or can be significantly less perforated; this increases the protection against changes in the moisture content of the product, ie product shelf life is significantly increased.

It should be noted that not only plastic films can be used as barrier layers, but also any other type of film or web which is thin, planar and flexible and which gives the same result. This also includes metal foils, polyethylene films and paper films with and without coating, wherein the coating may be, for example, a paint, plastic or metal.

The invention will be explained in more detail below with reference to a drawing:

It is a valve bag 1 with bottom 2 and upper part 3 shown schematically in plan view, wherein the bottom 2 and the upper part 3 are folded onto the front side 4 of the valve bag 1. Not recognizable is the back, which is below the front 4 and is congruent with this. Such a paper bag is made of an inner layer of paper or paper composite with a rectangular shape and a dekkungsgleichen outer layer, which is also made of paper or paper composite and is rectangular. Four short cuts are made at the bottom and top edges of the two paper layers, while the rest is folded. Here are two parallel to each other and over the height of the blanks extending fold lines side edges 5 and 6. In the filled state disappear the side edges 5 and 6 and it forms a bag with a width B, a depth T and a height H.

The inner layer of the paper bag 1 is not usually treated as it is not visible in use and also does not need to be printed. The congruent outer layer, however, may have undergone such treatment that it can be easily printed and also provides a pleasing appearance.

According to the invention, one or more barrier layers are now inserted between the one-piece inner layer and the likewise one-piece outer layer, the edges 8, 10 of which overlap.

The edges 8 and 10 of the barrier layer or the barrier layers run parallel to the side edges 5 and 6 of the paper bag 1. The overlap area A preferably makes 1/5 to 1/20 of the width B of the paper bag 1, preferably 1/10. Thus, A = 0.2B to 0.05B, preferably 0.1 B, applies. It should be noted that the values given are not exact values but merely indicate the desired range.

When using a single barrier layer so the right edge 10 of the barrier layer overlaps the underlying left edge 8 to the area A. Further, the left in the drawing part of the barrier layer is glued to a glue line 7 on the inner layer of the paper bag 1, the distance X to the right edge 8 and parallel to this over the height H of the paper bag 1 runs.

When two or more, typically three to four barrier films are used, each barrier or barrier film adheres along one edge through an adhesive line 7 to the inner layer or outer layer of the paper bag 1, while each other opposite edge not provided with an adhesive line Part of an adjacent barrier layer overlaps, which is also attached like the aforementioned barrier layer with a glue line to the inner layer or the outer layer of the paper bag. In this way, adjacent barrier layers or barrier films overlap like tiles, so that always the unpaved edge of a first barrier layer covers or overlaps the attached edge of each subsequent adjacent barrier layer.

It should again be noted that in this description of the invention with "edge" of the barrier layer is meant in each case the edge 8, 10, which runs parallel to the side edges 5 and 6 of the paper bag 1, but not the upper edge 11 or the lower edge 12 which run across the upper part 3 and the bottom 2. The reason for this is the production of the paper sack, which is produced in a first manufacturing stage as a paper tube and cut in a further manufacturing stage to the length H. Thus, the barrier layer or barrier film initially also only a longitudinal extent with the edges 8 and 10, because the transverse thereto extending upper edges 11 and lower edges 12 arise only after the cut to the lengths H.

In the drawing is also shown how the bottom 2 and the upper part 3 are folded, with a piece of paper 9 is glued over the bottom 2 and the upper part 3, to close the bottom 2 and top 3.

In the drawing, it is also indicated that on one side of the upper part 3, a valve 13 is formed, which is formed by a known tubular nozzle, which can be pushed under the slip 9 and thus in the cross bottom.

The barrier layer according to the invention is provided in one embodiment with holes or perforations, for example, by needling with a needle head according to DE 203 19 771 U1 can be made. This additionally improves the escape of air.

The operation of the invention can be explained as follows:

At the moment of filling, a large volume percentage of air is introduced into the paper bag together with the contents. It is needed to transport the product from the silo to the packing machine. This air is disruptive to the filling process and should be transported as quickly as possible by venting to the outside.

During filling this air hits the inner layer. By using air-permeable paper (with and without perforation) this position of the bag does not present a major obstacle. Then this air strikes a barrier of whatever kind; the latter greatly affects the venting. Therefore, it is usually provided with small holes or slots or perforated. Another venting takes place via the barrier layer overlap, which is not glued.

With the use of a specially applied longitudinal bonding of the barrier layer, it is possible to guide the air between the inner layer and barrier layer so that a much faster occurring air outlet behind the barrier layer can take place. This applies to both a perforated and an imperforate barrier layer. After that, the air collects in front of the outer layer, where it can be removed with known technology.

Claims (4)

1. Paper bag with film overlap for fine-grained bulk materials such as cement, gypsum, granulate, animal feed, etc., with a bottom (2), for example a star-seal bottom, and with an upper part (3) located opposite the bottom (2), in which a valve tube (13) is arranged for filling the paper bag (1), whereby the paper bag (1) is formed of an inner layer of paper and an outer layer of paper or paper compound, between which there is at least one barrier layer with two substantially parallel edges (8, 10) that run from the bottom (2) to the upper part (3), characterized in that the at least one barrier layer is adhered to the inner layer or to the outer layer by means of a bonding line (7) along one edge (8), and its other, free edge (10) overlaps the bonded edge (8).
2. Paper bag as in Claim 1, characterized in that the edges (8, 10) of two, three, four or more barrier layers overlap in the manner of roof tiles in such a way that one free, unattached edge (10) always overlaps an edge (8) that is attached by means of a bonding line (7).
3. Paper bag as in Claim 2, characterized in that the barrier layer or barrier layers are films of plastic, metal, paper or similar.
4. Paper bag as in Claim 3, characterized in that the barrier layer or barrier layers are furnished with holes, slits or perforations, which permit the air to be discharged, but prevent the entry of water vapour.

Images