EP3092179B1 - Paper sack - Google Patents

Description

The invention relates to a paper bag, preferably a valve paper bag, for bulk material such as cement, gypsum, granules, animal feed or the like, with a bottom, preferably a cross or block bottom, and with a top opposite the bottom, in which optionally a valve tube is arranged to fill the paper bag.

Such paper bags are known, for example from the EP 1 858 769 B1 which provides between paper-like inner and outer layers one or more barrier layers whose edges overlap; an adhesion of the overlaps is not provided; only the adhesion to the inner or outer layer is ensured by gluing. In particular, the usual sizes are 5 kg, 10 kg or 25 kg.

For filling such bags usually a valve tube is provided, which is incorporated in the upper part and is plugged for filling on a filler neck. Essential for a quick and economical filling is a rapid escape of the air during the filling process. On the other hand, the bag should be as tight as possible after filling. In order to achieve a higher product protection and a longer product stability of the filling material, can - as in the EP 1 858 769 B1 described - be said barrier layer between the inner layer and the outer layer of paper inserted.

It has been found that sufficient protection of the product can not be guaranteed with the previously known sacks for sensitive products. Such sensitive fillers are, for example, fast-binding products in the field of building materials or food, in which a loss of flavor must be prevented.

In addition, there is a demand for so-called weatherproof paper sacks whose outer side has water or weather resistant material properties in order to ensure weather resistance over a certain period of time. In this embodiment, it is also necessary to provide sufficient ventilation of the paper bag during the filling process.

The present invention therefore deals with the improvement of a known paper bag in order to meet the above requirements. In particular, by means of the improved paper bag to ensure increased product protection and / or prolonged product stability of the filling material and / or increased weather resistance of the packaging material and at the same time an economical production and rapid ventilation during filling can be achieved.

According to the invention, this object is achieved in a first variant by a paper bag having the features of patent claim 1.

According to this embodiment of the invention, the paper bag comprises at least one paper layer with an overlap which is adhesively sealed to the bag interior. In this case, the position of the paper layer facing the interior of the bag has an air-permeable region in the region of the overlap, which area is covered by the layer of the paper layer facing the exterior of the bag. This at least one paper layer has, at least in some areas, a weatherproof coating facing the exterior of the bag. Weatherproof is a waterproof or at least water-repellent material coating. The bond can be waterproof and / or airtight.

By this embodiment, a so-called weather-resistant bag is created, which significantly increases the weather resistance of the paper bag and the filled contents can protect even with outdoor storage for a sufficient period of time from external influences. In particular, the contents can be effectively protected from moisture or rain.

The weatherproof coating can be either waterproof / water repellent or ideally also gas tight to additionally seal the paper bag against the passage of air, oxygen, CO2 or gaseous water. Furthermore, the coated paper layer has an overlap, wherein the overlapping edges are preferably parallel to the side edges of the paper bag, so that the overlap extends in the manner of an overlap strip from the bottom to the top.

In the case of the paper sacks according to the invention, the overlap of the coated paper layer with the interior of the bag is sealed in a sealing manner, that is to say in the case of the paper bags. H. in the region of the overlap, the inner layer facing the inside of the bag is glued to the layer of the coated paper layer which faces the outside of the bag, and the glue is located in the edge region of the overlap towards the bag interior.

Although the bonding directly on the edge of the overlap is advantageous, but the bond must not be located directly on the edge of the overlap to the bag interior. Rather, it may be moved away from the edge of the overlap, because even in this case, the intended purpose according to the invention can still be achieved.

In the region of the overlap, the layer of the coated paper layer facing the interior of the bag has an air-permeable region or a region with a higher air permeability than the remaining region of the paper layer. This air-permeable area is covered by the position of the overlap facing the exterior of the bag. Due to this configuration, air can escape during filling of the bag with filling material and escape to the outside of the overlap, since the obstructive for the air flow bonding is arranged to the bag interior. The bonding to the interior of the bag thus has a directing effect on the air flow, as well as a stabilizing effect for the coated paper layer in the region of the overlap, thus serving to hold the material ends together in the region of the overlap. It can thereby be achieved that the air exiting through the air-permeable region during filling can completely escape from the overlapping region to the outside. Furthermore, the stability in the overlap area is improved and the tightness in the filled state is increased.

Furthermore, the leakage of filling material can be avoided by the overlap. By suitable design of the air-permeable area can be ensured that the respective contents are retained in the bag, while only or mainly air can escape through the air-permeable area. When the bag is completely filled, the air-permeable area in the area of the overlap is covered by the outer layer of the inner layer, so that the penetration of substances or liquids from the outside is avoided.

The inventive design a good ventilation during filling is achieved at the same time high product protection against external influence. The outer coating ensures adequate protection of the contents against external influences, such as moisture and water.

The aforementioned task is further solved in a second variant by a paper bag according to the features of claim 2. Accordingly, the paper bag has at least one coated paper layer with a gas-tight coating facing the interior of the bag. In addition, the coated paper layer has an overlap on, which is adhesively sealed to the interior of the bag, and in the region of the overlap facing the interior of the bag coated layer of paper has an air-permeable area, which is covered by the facing to the outside of the bag layer of the coated paper layer. The configuration of the overlap thus corresponds to the abovementioned first embodiment of the paper bag according to the invention. The difference from the first embodiment is that the paper layer having an overlap does not necessarily have an outer coating, but is provided with an inner gas-tight coating. Furthermore, according to the invention, at least one conventional layer is provided, in particular of paper or a composite paper, which is arranged between the filling space and the at least one overlapping paper layer.

Consequently, the gas-tight coating does not have to be directly connected to the filling material, but an arbitrary arbitrary layer, in particular paper layer, can be provided. The gas-tight coating prevents air, oxygen, CO ₂ or gaseous water from penetrating in relevant quantities from the outside and damaging or destroying the filling material. These gases are primarily responsible for damage to sensitive products or for the low storage stability of such products.

Advantageous embodiments of the two Papieracksausführungen invention according to claims 1 and 2 are the subject of the dependent claims.

In an advantageous embodiment it can be provided that the coated paper layer is coated on both sides. For the first embodiment, it applies that the outside coated paper layer may additionally comprise an internal gas-tight coating. For the second embodiment, an external water-repellent or water-resistant coating is provided in addition to the internal gas-tight coating. This embodiment with a two-sided coating of the at least one paper layer is suitable in particular for deposit-paper sacks, which consist only of a single paper layer. Of course, double-sided coated paper layers can also be used for multi-ply paper sacks.

Instead of the double-sided coating, provision may be made for a further paper layer to be provided in addition to a paper layer with an outer-side coating, which likewise comprises the described overlap with an air-permeable region and which comprises an inner coating. The same applies to the second embodiment of the invention, which is arranged in addition to the at least one paper layer with internal gas-tight coating another paper layer with the overlap described and external coating, in particular water-resistant or water-resistant coating. By these advantageous embodiments, on the one hand, a gas-tight paper bag is provided, which prevents the entry of oxygen, CO2 or gaseous water in relevant quantities from the outside into the medium and at the same time offers a certain weather resistance for outdoor storage.

Of course, one or more conventional inner or outer layers, in particular paper layers or layers of a paper composite, may be provided in addition to the coated paper layers having overlaps. Of course, it is also conceivable layers of another material or composite material. Conventional layers are to be understood as meaning layers which either have no overlap or an overlap without a separate air-permeable region.

Ideally, the air permeable area of the coated paper layer is provided with one or more perforations, which are preferably formed by a needling and / or one or more slits. This ensures sufficient air exchange through the coated paper layer. In another variant, the perforations may be formed as microperforations, which can be produced for example by electrical or chemical means and are known from cigarette paper.

Alternatively, the air-permeable area of the coated paper layer may be provided by a highly porous material, that is, the paper layer is characterized in the air-permeable area by deviating material properties that allow an exchange of air or higher air exchange compared to the non-air-permeable area.

Furthermore, it is conceivable to make the coated paper layer permeable to air in the air-permeable area by partially recessing the coating.

A wider overlap area allows a larger area of the air permeable area of the overlap area and thus better ventilation during filling. A disadvantage of a larger overlap area is the higher material costs for the inner layer. In this conflict of objectives, it has proved to be advantageous if the overlap of the inner layer amounts to at least 3% of the bag circumference, moreover at least 10% of the bag circumference and even more advantageously at least 17% but at most 25% of the bag circumference.

In another preferred embodiment, the inner and / or outer coating, d. H. the gas-tight and / or water-resistant / waterproof coating has a multilayer structure. The gas-tight coating preferably comprises a metallized film and / or a metal foil. By such metallized films or metal foils, a particularly good gas tightness can be achieved. Very suitable as a metallic material is aluminum. The metallic gas barrier ensures particularly good aroma protection in the food industry.

For the embodiment of a water-resistant or water-repellent coating, the use of at least one lacquer layer and / or at least one wax layer and / or at least one plastic layer and / or at least one oil layer and / or likewise a metal layer or metal foil is particularly suitable. In a multilayer embodiment of the coating of the coated paper layer may preferably be discharged through the water-resistant or water-repellent or gas-tight coating, an additional layer which is to serve the protection of the subordinate coating. This prevents the destruction of, for example, a metal foil or a lacquer layer.

Advantageously, the gas-tight coating also forms a barrier to liquid, so that a seal against the ingress of water is achieved.

According to the invention in both variants according to claims 1 and 2 additionally in a central region and / or in the edge region of the overlap to the bag exterior additional bonds available. These bonds further stabilize the overlap area. It is advantageous that at least one of these bonds at least partially permeable, d. H. permeable to air, is formed to the outside of the bag, advantageously by interrupted glue lines along the edge of the overlap to the bag exterior.

In a particularly advantageous embodiment of the invention, in addition to the adhesion provided for the interior of the sack, a central interrupted glue line may be provided, while the gluing provided in the edge region of the overlap with the exterior of the bag is continuous and thus sealing. In this case, it is expedient if, in addition, the position of the coated paper layer facing the outer side of the bag also has an air-permeable region in the region of the overlap. This air-permeable area is then provided in the area between the gluing lying on the outer edge and the middle gluing.

Also, this air-permeable area can be done for example by a recess of the coating and / or by design of the paper layer in this area with a highly porous material. The area may as well be realized by the provision of one or more perforations. The perforations are ideally carried out in an analogous manner to the perforations of the interior facing the bag. The advantageous embodiment is an additional Protection is ensured, since also to the outside a hermetically sealed bonding of the outer overlap is ensured. In order nevertheless to allow an exchange of air to the outside, therefore, the outer overlap must be equipped with a corresponding air-permeable area. The air exchange between the inner air-permeable configuration of the inner paper layer and the outside air-permeable designed paper layer is carried out by the middle bonding, which is permeable to air, ie as a non-continuous adhesive strip executed. Ideally, the air-permeable areas of the interior of the bag and the exterior of the bag do not overlap, or only slightly or partially over one another, in order to produce an angled air channel from the inside to the outside.

In a further preferred embodiment, the paper bag or a single paper layer has a plurality of overlaps according to the invention, particularly preferably an overlap according to the invention on the front side of the bag and a further overlap according to the invention on the back of the bag. Thus, the ventilation of the bag can be improved during filling and distributed on both sides.

In other preferred embodiments, the paper bag according to the invention has, outside the coated paper layer, further paper layers or layers of other materials suitable for bag production. These layers must also be designed so that they allow the air to escape to the outside during filling. Suitable sack materials are suitable materials, preferably paper, coated paper, film and / or coated film. This may be useful with paper bags coated on the outside. The wrapper then serves, for example, as additional protection for the transport, etc. In order to achieve the weather resistance, this additional wrapper is removed, and the at least one paper layer with external weatherproof coating then forms the outermost surface of the paper bag.

Fig. 1:

eine schematische Draufsicht auf einen Ventilsack mit Boden und Oberteil,

Fig. 2a:

ein schematischer Querschnitt durch den Papiersack gemäß Fig. 1 entlang der Linie A-A,

Fig. 2b, 2c:

zwei weitere Querschnittdarstellungen entlang der Linie A-A gemäß alternativen Beispielen,

Fig. 3:

die beschichtete Papierlage einer erfindungsgemässen Ausgestaltungen gemäß den Fig. 2a, 2b, 2c mit einem vergrößerten Ausschnitt der Überlappung mit Verklebung,

Fig. 4:

eine vergrößerte Darstellung des Schichtaufbaus der Beschichtung gemäß der vorliegenden Erfindung und

Figur 5:

ein Schlauchabschnitt aus der beschichteten Papierlage des Ventilsackes gemäß dem Ausführungsbeispiel der Figur 2a.

Various embodiments of the invention will be explained in more detail with reference to the following figures. Showing:

Fig. 1:

a schematic plan view of a valve bag with bottom and top,

Fig. 2a:

a schematic cross section through the paper bag according to Fig. 1 along the line AA,

Fig. 2b, 2c:

two further cross-sectional views along the line AA according to alternative examples,

3:

the coated paper layer of an inventive embodiments according to the Fig. 2a, 2b . 2c with an enlarged section of the overlap with gluing,

4:

an enlarged view of the layer structure of the coating according to the present invention and

FIG. 5:

a hose portion of the coated paper layer of the valve bag according to the embodiment of FIG. 2a ,

Fig, 1 shows a paper bag 10 with a cross bottom 2 and a top 3, wherein the bottom 2 and the top 3 are folded on the front side 5 of the paper bag 10. Not recognizable is the back of the bag, which is below the front 5. In the upper part 2, a valve tube 4 is inserted.

The illustrated basic principle of the paper bag of the Fig. 1 can be one or more layers. In case of FIG. 1 The paper bag comprises two layers, which in the cross-sectional view of FIG. 2a is clearly visible along the section line AA.

FIG. 2a shows a preferred variant of the paper bag as a multi-layer bag. The paper bag consists of an outer coated paper layer 20, which has an overlap 22 with splice 24. The sealing bond 24 is formed toward the interior of the bag. The paper layer 20 also has an external coating with weatherproof material properties. In particular, the coating is waterproof or water repellent. In addition, the example according to the Fig. 2a another inner layer 18, for example made of paper or a paper composite. This paper layer also has an overlap 19 with splice 25. A comparison of the two overlaps 19, 22 shows that the overlap 22 is made significantly wider. Both paper layers 20 form a tube section of the paper bag Fig. 1 between the bottom 2 and top 3 from. The wider overlap 22 serves to adequately vent the paper bag during its filling.

Fig. 2b shows an alternative variant of the paper bag as Einlagensack. In this case, the outer paper layer 20 is analogous to the example of Fig. 2a executed.

Fig. 2c shows a variant with a coated paper layer 20 which is embedded between two further layers 18 and 21. The overlaps of the outer and inner layers 18, 21 are also significantly narrower than the overlap 22 of the coated paper layer 20 is formed. The paper layer 20 may also like the paper layer of Fig. 2a, 2b be executed.

Basically, the coating of the paper layer 20 of the Figure 2c may also be internally coated with a water-resistant / water-repellent or gas-tight. It is conceivable with regard to all figures and a paper layer 20 with double-sided coating, for example with an inner gas-tight coating and an external water-resistant / water-repellent coating. This embodiment is in particular in the bag according to FIG. 2b meaningful. In principle, the paper layer 20 - contrary to the claimed invention - of course, be carried out without coating, wherein by means of the enlarged overlap 22 then a better Air permeability to the non-overlapped region of the paper layer 20 can be achieved. It is also conceivable that in the examples of the FIGS. 2a, 2b . 2c Additional paper layers are provided with enlarged overlaps, for example, to ensure at least two sides of the bag for adequate ventilation. Of course, more conventional layers 18, 21 may be provided.

Fig. 3 shows the coated paper ply 20 with an enlarged section of the overlap 22. In the area of the overlap 22, the layer 31 of the coated paper ply 20 which faces the interior of the ply overlaps the outward facing ply 32 of the coated paper ply 20. The overlap is at its edge facing the interior of the bag 22 adhesively bonded by means of bonding 24.

In addition to the bond 24, the overlap according to the invention comprises further adhesion sites 33, 34, the adhesion site 33 being an interrupted adhesive strip in the longitudinal direction of the sack Fig. 1 is executed and the bond 34 is a continuous longitudinally extending adhesive strip. To the advantages of the additional bonds 33, 34 will later with reference to Fig. 5 To be received.

Fig. 4 shows by way of example the layer structure of the coated paper layer 20. In the case of an internal coating, the paper layer has on its outer side a carrier layer 41 made of paper. Inwardly, the next layer is followed by a metallization 42, which is preferably formed from aluminum. The metallization 42 is protected by a plastic coating which consists in its core 43 of PET (polyethylene terephthalate) or comparable plastics. The core 43 is provided on both sides with a surface layer or surface treatment 44. Between the metallization 42 and surface treatment 44 is a lacquer layer 45. On the outer surface treatment 44 is a corona pretreatment 46, which then forms the innermost layer towards the interior of the bag. The plastic coating applied to the metallic gas barrier protects the metal layer against damage during the manufacture of the bag.

For an external coating, the paper layer 20 has on its inside a carrier layer 41 made of paper. The outward-following layer 42a then comprises a water-resistant or water-repellent material, preferably a lacquer layer, an oil layer, a protective layer, a plastic layer or a metal layer, which is particularly preferably made of aluminum. The layer 42a is protected analogously to the inner coating by a plastic coating, which consists in its core 43 of PET (polyethylene terephthalate) or comparable plastics. The core 43 is provided on both sides with a surface layer or surface treatment 44. Between the layer 42 and the surface treatment 44 is a lacquer layer 45. On the outer surface treatment 44 is a corona pre-treatment 46, which then forms the outermost layer towards the exterior of the bag. The plastic coating applied to the water-resistant or water-repellent layer 42a protects this layer from damage during bag production. For a coating on both sides, the described layer structure can be applied on both sides of the carrier material 41.

Fig. 5 now shows a specific embodiment of the overlapping region 22 of the paper layer 20 according to the invention. The entire overlap region 22 of the interior 31 facing the interior of the bag and the layer 32 facing the exterior of the bag are glued air-tight and watertight by means of the continuous adhesive strip 24. In addition to the existing bond 24 comes a parallel adhesive strip 33 which extends in the middle portion of the overlap 22. This adhesive strip 33 is interrupted, whereby a gas outlet is allowed to the outside, ie from the bag inside to the outside.

Perforations 37 in the form of needling, which form the air-permeable region of the overlap 22, are provided on the inner layer 31 between the two bonds 24, 33. Thus, despite the sealing bond 24 and the coating of the paper layer 20 air during the filling process on the perforations 37 and the broken bond 33 escape to the outside. The air permeability can of course also by using a highly porous Material can be achieved in this area of the paper layer 20. In addition, it is possible to simply leave an applied coating of the paper layer 20 in this area in order to provide the necessary air permeability.

In principle, the outer layer 32 can be cut off after the bonding 33. However, a better protection of the contents results when the outer layer 32 - as in FIG. 5 shown - the bond 33 surmounted and bonded at the edge with a continuous adhesive strip 34 with the inner layer 31. Also, this bond 34 is preferably sealing. Nevertheless, in order to ensure sufficient air leakage, also the exterior of the flap 36 facing the outer side facing the outer layer 32, in the Fig. 5 hatched, permeable to air. This can be achieved analogously to the inner layer 31, for example by recessing a coating in the region 36 or by using a highly porous paper or perforations. The air outlet region 36 and the perforation region 37 are therefore not one above the other, but laterally offset from one another.

The air which is produced during filling of the bag 10 and escapes through the perforation 37 of the layer 31 facing the interior of the bag can now escape to the outside through the overlap region 36 facing the exterior of the bag.

With the invention, a number of advantages are achieved. In particular, the paper bag can be well vented during filling by the configuration of the overlap 22 and the gas-tight coating on the inside or a water-resistant coating on the outside of the bag can be a high product protection of the filling or a weather-resistant design of the paper bag 10 reach.

The embodiment of the overlap 22 is used, for example, not only for coated layers of a paper bag, but is also suitable for those layers which have neither on the inside nor on the outside of a corresponding coating and basically air-permeable properties exhibit. The design of a corresponding overlap with air-permeable region is particularly desirable if the basic material property of the layer does not have sufficient air permeability. In this case, overlapping and forming an air permeable area with higher air permeability over the remaining material area of the ply may result in better venting when filling the paper bag. Against this background, the design of a paper bag is suitable, in which at least one arbitrary layer, for example the inner, outer or an intermediate layer is provided with a corresponding overlap. This bag need not necessarily comprise a coated paper layer or a coated paper layer with an overlap 22.

In another possible scenario, it may also be provided that a layer which is not made of paper and introduced as an additional barrier layer is likewise provided with the correspondingly described overlap 22. Such a barrier layer can be, for example, a plastic film which is intended to protect the filled product against the ingress of liquid or gases. In order to achieve adequate ventilation during the filling of the paper bag, this plastic film or another gas-tight layer may be provided with the appropriate overlap. This bag need not necessarily comprise a coated paper layer or a coated paper layer with an overlap 22. In addition, in the material region of the plastic film outside the overlap 22, further perforations or otherwise pronounced air-permeable regions may be provided.

Claims (13)

1. A paper sack (10) for bulk material such as cement, gypsum, granulate, animal feed or similar, having a base (2), preferably a cross bottom or block bottom, and having an upper part (3) which is disposed opposite the base (2) and in which a valve tube (4) is optionally arranged for filling the paper sack (10), wherein the paper sack (10) has at least one paper layer (20) having an overlap (22) which is sealingly adhesively bonded toward the sack interior in that the layer (31) of the overlap (22) facing the sack interior is adhesively bonded to the layer (32) of the overlap (22) facing toward the sack exterior; wherein the layer (31) of the paper layer (20) facing the sack interior has an air-permeable region (37) in the region of the overlap (22) which is covered by the layer (32) of the paper layer (20) facing the sack exterior; wherein the at least one paper layer (20) has a water-repellent/water-tight coating (42a) facing the sack exterior at least regionally; and wherein the overlap (22) has additional adhesive bonds (33, 34) in a middle region and/or in the region of its margin to the sack exterior, with at least one of the additional adhesive bonds (33) preferably being permeable to the sack exterior, for example as interrupted adhesive lines in the longitudinal direction of the paper sack (10).
2. A paper sack (10) for bulk material such as cement, gypsum, granulate, animal feed or similar, having a base (2), preferably a cross bottom or block bottom, and having an upper part (3) which is disposed opposite the base (2) and in which a valve tube (4) is optionally arranged for filling the paper sack (10), wherein the paper sack (10) has at least one coated paper layer (20), having a gas-tight coating (42) facing the sack interior; wherein the coated paper layer (20) has an overlap (22) which is sealingly adhesively bonded toward the sack interior in that the layer (31) of the overlap (22) facing the sack interior is adhesively bonded to the layer (32) of the overlap (22) facing toward the sack exterior; wherein the layer (31) of the paper layer (20) facing the sack interior has an air-permeable region (37) in the region of the overlap (22) which is covered by the layer (32) of the paper layer (20) facing the sack exterior; wherein the paper sack (10) is of multi-layer design and a conventional layer (18), in particular a paper layer, is arranged between the filling material and the at least one paper layer (20); and wherein the overlap (22) has additional adhesive bonds (33, 34) in a middle region and/or in the region of its margin to the sack exterior, with at least one of the additional adhesive bonds (33) preferably being permeable to the sack exterior, for example as interrupted adhesive lines in the longitudinal direction of the paper sack (10).
3. A paper sack (10) in accordance with one of the preceding claims, characterized in that the coated paper layer (20) is coated at both sides, in particular with an inwardly disposed gas-tight coating (42) and with an outwardly disposed water-repellent/water-tight coating (42a).
4. A paper sack (10) in accordance with one of the preceding claims, characterized in that the water-repellent/water-tight coating (42a) of the paper layer (20) facing the sack exterior forms the outer surface of the paper sack (10).
5. A paper sack (10) in accordance with one of the preceding claims, characterized in that the paper sack (10) has a further paper layer (20) having an overlap (22) which is sealingly adhesively bonded toward the sack interior and the layer (31) of the paper layer (20) facing toward the sack interior has an air-permeable region (37) in the region of the overlap (20) which is covered by the layer (32) of the paper layer (20) facing the sack exterior, and with this paper layer (20) being coated in a gas-tight manner at the inner side and/or being coated in a water-repellent or water-tight manner at the outer side.
6. A paper sack (10) in accordance with one of the preceding claims, characterized in that the paper sack (10) comprises one or more conventional inner layers and/or outer layers (18, 21), in particular paper layers.
7. A paper sack (10) in accordance with one of the preceding claims, characterized in that the air-permeable region (37) of the coated paper layer comprises an uncoated region and/or a highly porous material and/or perforations (37), with the perforation preferably being formed by needling and/or one or more slits.
8. A paper sack (10) in accordance with the preceding claim, characterized in that the overlap (22) of the paper layer (20) amounts to at least 3% of the sack periphery, preferably at least 10% of the sack periphery, and further preferably at least 17% to a maximum of 25% of the sack periphery.
9. A paper sack (10) in accordance with one of the preceding claims, characterized in that the coating (42, 42a) of the coated paper layer is of multi-layer design.
10. A paper sack (10) in accordance with one of the preceding claims, characterized in that the coating (42, 42a) of the coated paper layer (20) comprises at least one metal layer (42) and/or at least one lacquer layer (42a) and/or at least one oil layer and/or at least one wax layer and/or at least one plastic layer.
11. A paper sack (10) in accordance with one of the preceding claims, characterized in that the layer (32) of the coated paper layer (20) facing the sack exterior has an air-permeable region (36) in the region of the overlap (22), in particular in the form of a coating omission and/or of a highly porous material and/or of perforations, with the perforation preferably being formed by needling and/or by one or more slits, with this air-permeable region (36) preferably not overlapping or only partly overlapping with the air-permeable region (37) of the layer (31) facing the sack interior.
12. A paper sack (10) in accordance with one of the preceding claims, characterized in that the at least one paper layer (20) has further overlaps (22) which are configured in accordance with one of the preceding claims, preferably such that one overlap is formed on the front side (5) of the sack and a further one is formed on the rear side.
13. A paper sack (10) in accordance with one of the preceding claims, characterized in that one or more further material layers (21) are present as a covering of the coated paper layer (20), which further material layers allow air to escape to the outside on the filling of the paper sack (10) and which are formed from materials suitable for sack manufacture, preferably from paper, coated paper, film and/or coated film.

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