Paper bag

Abstract

A paper sack for bulk material such as cement, gypsum, granulate, animal feed or similar, having a base, preferably a cross bottom or block bottom, and having an upper part which is disposed opposite the base and in which a valve tube is optionally arranged for filling the paper sack, wherein the paper sack has at least one paper layer having an overlap which is sealingly adhesively bonded toward the sack interior; and wherein the layer of the paper layer facing the sack interior has an air-permeable region in the region of the overlap which is covered by the layer of the paper layer facing the sack exterior. The at least one paper layer at least regionally has a water-repellent/water-tight coating facing the sack exterior.

Claims

1. A paper sack (10) for bulk material such as cement, gypsum, granulate, animal feed or similar, having a base (2), and an upper part (3) which is disposed opposite the base and in which a valve tube (4) is arrangable for filling the paper sack (10), wherein the paper sack (10) has at least one paper layer (20) having an overlap (22), an inner layer (31) of the at least one paper layer (20) facing a sack interior has a perforated air-permeable region (37) in the region of the overlap (22), wherein the perforated air-permeable region which is covered by an outer layer (32) of the at least one paper layer (20) facing a sack exterior, the at least one paper layer (20) has a water-repellent/water-tight coating (42a) facing the sack exterior at least regionally, a first adhesive bond (24) continuously extends without interruption along a line between the inner and outer layers (31, 32) between the sack interior and the perforated air-permeable region (37), a second adhesive bond (33) discontinuously extends with interruptions along a line between the inner and outer layers (31, 32) on an opposite side of the perforated air-permeable region (37), a third adhesive bond (34) continuously extends without interuption along a line between the inner and outer layers (31, 32) on a side of the second adhesive bond (33) opposite the perforated air-permeable region (37), and said outer layer (32) of said overlap (22) comprises an air-permeable region (36) formed by omitting the water repellent/water-tight coating and positioned between said second and third adhesive bonds (33, 34) such that said air-permeable regions (37, 36) of said inner and outer layers (31, 32) are laterally and circumferentially offset from one another.

2. The paper sack (10) in accordance with claim 1, wherein the at least one paper layer (20) is coated at both sides with an inwardly disposed gas-tight coating (42) and with the outwardly disposed water-repellent/water-tight coating (42a), except in the air-permeable region (36) of the outer layer.

3. The paper sack (10) in accordance with claim 1, wherein the water-repellent/water-tight coating (42a) of the at least one paper layer (20) facing the sack exterior forms the outer surface of the paper sack (10).

4. The paper sack (10) in accordance with claim 1, wherein the at least one paper layer (20) is coated in a gas-tight manner at an inner side thereof, except in the air-permeable region (36) of the outer layer.

5. The paper sack (10) in accordance with claim 1, wherein the paper sack (10) comprises one or more conventional inner layers and/or outer layers (18, 21) of paper.

6. The paper sack (10) in accordance with claim 1, wherein the overlap (22) of the at least one paper layer (20) amounts to at least 3% of the sack periphery.

7. The paper sack (10) in accordance with claim 6, wherein the overlap (22) of the at least one paper layer (20) amounts to at least 10% of the sack periphery.

8. The paper sack (10) in accordance with claim 7, wherein the overlap (22) of the at least one paper layer (20) amounts to at least 17% to a maximum of 25% of the sack periphery.

9. The paper sack (10) in accordance with claim 1, wherein the water repellent/water-tight coating (42, 42a) of the at least one paper layer is of multi-layer design.

10. The paper sack (10) in accordance with claim 1, wherein the water repellent/water-tight coating (42, 42a) of the at least one 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. The paper sack (10) in accordance with claim 1, wherein the at least one paper layer (20) has further overlaps (22) which are configured such that one overlap is formed on the front side (5) of the sack and a further one is formed on the rear side.

12. The paper sack (10) in accordance with claim 1, wherein one or more further material layers (21) are present as a covering of the at least one 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 paper, coated paper, film and/or coated film.

13. A paper sack (10) for bulk material such as cement, gypsum, granulate, animal feed or similar, having a base (2), and an upper part (3) which is disposed opposite the base (2) and in which a valve tube (3) is arrangable 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 a sack interior, the at least one coated paper layer (20) has an overlap (22), an inner layer (31) of the at least one coated paper layer (20) facing the sack interior has a perforated air-permeable region (37) in the region of the overlap (22), wherein the perforated air-permeable region which is covered by an outer layer (32) of the at least one coated paper layer (20) facing a sack exterior, the paper sack (10) is of multi-layer design and a paper layer (18) is arranged between the filling material and the at least one coated paper layer (20), a first adhesive bond (24) continuously extends without interruption along a line between the inner and outer layers (31, 32) between the sack interior and the perforated air-permeable region (37), a second adhesive bond (33) discontinuously extends with interruptions along a line between the inner and outer layers (31, 32) on an opposite side of the perforated air-permeable region (37), a third adhesive bond (34) continuously extends without interruption along a line between the inner and outer layers (31, 32) on a side of the second adhesive bond (33) opposite the perforated air-permeable region (37), and the perforated air-permeable region (37) of said inner layer (31) is positioned between said first and second adhesive bonds (24, 33) and said outer layer (32) of said overlap (22) comprises an air-permeable region (36) formed by omitting the gas-tight coating and positioned between said second and third adhesive bonds (33, 34) such that said air-permeable regions (37, 36) of said inner and outer layers (31, 32) are laterally and circumferentially offset from one another.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Various embodiments of the invention will be explained in more detail with reference to the following Figures. There are shown:

(2) FIG. 1: a schematic plan view of a valve sack in accordance with the invention with a base and an upper part;

(3) FIG. 2a: a schematic cross-section through the paper sack in accordance with the invention in accordance with FIG. 1 along the line A-A;

(4) FIGS. 2b, 2c: two further cross-sectional representations along the line A-A in accordance with alternative embodiments;

(5) FIG. 3: the coated paper layer of one of the embodiments in accordance with FIGS. 2a, 2b, 2c with an enlarged section of the overlap with adhesive bond;

(6) FIG. 4: an enlarged representation of the layer design of the coating in accordance with the present invention; and

(7) FIG. 5: a tube section of the coated paper layer of the valve sack in accordance with the embodiment of FIG. 2a.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

(8) FIG. 1 shows a paper sack 10 in accordance with the invention having a cross bottom 2 and an upper part 3, wherein the base 2 and the upper part 3 are folded onto the front side 5 of the paper sack 10. The rear side of the sack which lies beneath the front side 5 cannot be seen here. A valve tube 4 is inserted in the upper part 3.

(9) The basic principle of the paper sack in accordance with the invention of FIG. 1 shown can have a single-layer or a multi-layer design. In the case of FIG. 1, the paper sack comprises two layers, which is easily recognizable in the cross-sectional representation of FIG. 2a along the line A-A.

(10) FIG. 2a shows a preferred variant of the paper sack in accordance with the invention as a multi-layer sack. The paper sack comprises an outwardly disposed coated paper layer 20 which has an overlap 22 having an adhesive point 24. The sealing adhesive bond 24 is formed toward the sack interior in this respect. The paper layer 20 additionally has an outwardly disposed coating having waterproof material properties. The coating is in particular watertight or water-repellant. In addition, the embodiment in accordance with FIG. 2a comprises a further inwardly disposed layer 18, for example composed of paper or of a paper composite. This paper layer also has an overlap 19 with an adhesive point 25. A comparison of the two overlaps 19, 22 shows that the overlap 22 is considerably wider. Both paper layers 20 form a tube section of the paper sack of FIG. 1 between the base 2 and the upper part 3. The wider overlap 22 serves the sufficient venting of the paper sack during its filling.

(11) FIG. 2b shows an alternative variant of the paper sack as an inlay sack. In this respect, the outer paper layer 20 is designed analogously to the embodiment of FIG. 2a.

(12) 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 outwardly disposed and inwardly disposed layers 18, 21 are likewise formed considerably narrower than the overlap 22 of the coated paper layer 20. The paper layer 20 can in this respect likewise be deigned like the paper layer of FIGS. 2a, 2b.

(13) It applies in general that the coating of the paper layer 20 of the FIGS. 2a, 2b, 2c can also only be coated inwardly disposed in a water-resistant/water-repellent or gas-tight manner. A paper layer 20 having a two-sided coating is also conceivable, for example with an inwardly disposed gas-tight coating and an outwardly disposed water-resistant/water-repellant coating. This embodiment is in particular useful with the inlay sack in accordance with FIG. 2b. In general, the paper layer 20 could naturally also be designed without a coating, with then a better air permeability being able to be achieved by means of the increased overlap 22 with respect to the non-overlapped region of the paper layer 20. It is also conceivable that further paper layers having increased overlaps are provided in the examples of FIGS. 2a, 2b, 2c in order, for example, to be able to provide sufficient venting at at least two sack sides. More conventional layers 18, 21 can naturally also be provided.

(14) FIG. 3 shows the coated paper layer 20 with an enlarged detail of the overlap 22. The layer 31 of the coated paper layer 20 facing toward the sack interior overlaps with the outwardly facing layer 32 of the coated layer 20 in the region of the overlap 22. The overlap 22 is sealingly adhesively bonded by means of the adhesive bonding 24 at its margin facing toward the sack interior.

(15) In addition to the adhesive bonding 24, the overlap 22 comprises further adhesive points 33, 34, with the adhesive point 33 being designed as an interrupted adhesive strip in the longitudinal direction of the sack of FIG. 1 and with the adhesive bond 34 being a continuous adhesive strip extending in the longitudinal direction. The advantages of the additional adhesive bonds 33, 34 will be looked at later with respect to FIG. 5.

(16) FIG. 4 shows the layer design of the coated layer 20 by way of example. In the case of an inwardly disposed coating, the paper layer has a carrier layer 41 of paper at its outer side. A metallization 42, which is preferably formed of aluminum, follows inwardly as the next layer. The metalizing 42 is protected by a plastic coating whose core 43 comprises PET (polyethylene terephthalate) or comparable plastics. The core 43 is provided at both sides with a surface layer or a surface treatment 44. A lacquer layer 45 is located between the metallization 42 and the surface treatment 44. A corona pre-treatment 44, which then forms the innermost layer toward the sack interior, is present on the outer surface treatment 44. The plastic coating applied to the metallic gas barrier protects the metal layer from damage on the sack manufacture.

(17) The paper layer 20 has a carrier layer 41 of paper at its inner side for an outwardly disposed coating. The outwardly following layer 42a then comprises a water-resistant or water-repellant material, preferably a lacquer layer, an oil layer, a wax layer, a plastic layer or a metal layer, which particularly preferably consists of aluminum. The layer 42a is protected, analog to the inner coating, by a plastic coating whose core 43 comprises PET (polyethylene terephthalate) or comparable plastics. The core 43 is provided at both sides with a surface layer or a surface treatment 44. A lacquer layer 45 is located between the metallization 42 and the surface treatment 44. A corona pre-treatment 46, which then forms the outermost layer toward the sack exterior, is present on the outer surface treatment 44. The plastic coating applied to the water-resistant or water-repellant layer 42a protects this layer from damage on the sack manufacture. The described layer design can be applied to both sides of the carrier material 41 for a two-sided coating.

(18) FIG. 5 now shows a specific embodiment of the overlap region 22 of the paper layer 20 in accordance with the invention. The total overlap region 22 of the layer 31 facing the sack interior and the layer 32 facing the sack exterior is adhesively bonded in an air-tight and water-tight manner by means of the continuous adhesive strip 24. In addition to the existing adhesive bond 34, there is a parallel adhesive strip 33 which extends in the middle section of the overlap 22. This adhesive strip 33 is interrupted, whereby a gas discharge to the outside is permitted, i.e. from the sack interior to the outside.

(19) Perforations 37 in the form of needling are provided between the two adhesive bonds 24, 33 on the inner layer 31 and form the air-permeable region of the overlap 22. Air can thus escape to the outside during the filling process via the perforations 37 and the interrupted adhesive bond 33 despite the sealing adhesive bond 24 and the coating of the paper layer 20. The air permeability can naturally also be achieved by using a highly porous material in this region of the paper layer 20. There is additionally the possibility of omitting an applied coating of the paper layer 20 in this region in order thus to provide the required air permeability.

(20) In general, the outer layer 32 can be cut off after the adhesive bonding 33. Better protection of the filling material results, however, when the outer layer 32as shown in FIG. 5projects beyond the adhesive bond 33 and is adhesively bonded at the marginal side to the inner layer 31 by a continuous adhesive strip 34. This adhesive bond 34 is also preferably sealing. In order nevertheless to provide sufficient air egress, the overlap region 36 facing toward the sack exterior of the layer 32, shown hatched in FIG. 5, facing the sack exterior must also be air-permeable. This can be achieved analogously to the inner layer 31, for example by omitting a coating in the region 36 or by using a highly porous paper or of perforations. The air egress region 36 and the perforation region 37 are therefore not above one another, but rather displaced laterally with respect to one another.

(21) The air which arises on the filling of the sack 10 and which escapes through the perforation 37 of the layer 31 facing the sack interior can now escape to the outside through the overlap region 36 facing the sack exterior.

(22) A number of advantages are achieved with the invention. The paper sack can in particular be well vented during filling due to the configuration of the overlap 22 and high product protection of the filling material or a weather-resistant design of the paper sack 10 can be achieved by the gas-tight coating at the inner side or by a water-resistant coating at the outer side of the sack.

(23) The design of the overlap 22 is used, for example, not only on coated layers of a paper sack, but is rather also provided for those layers which do not have a corresponding coating either at the inner side or at the outer side and generally have air-permeable properties. The configuration of a corresponding overlap with the air-permeable region is in particular desirable if the general material property of the layer does not have sufficient air permeability. In this case, a better venting can be achieved on the filling of the paper sack by the overlap and the formation of an air-permeable region having a higher air permeability with respect to the remaining material region of the layer. Against this background, the embodiment of a paper sack is expedient in which at least any designed layer, for example the inner layer, outer layer or an intermediate layer, is provided with a corresponding overlap. This sack does not necessarily have to comprise a coated paper layer or a coated paper layer having an overlap 22.

(24) In a further possible scenario, provision can likewise be made that a layer, not consisting of paper, introduced as an additional barrier layer is likewise provided with the correspondingly described overlap 22. Such a barrier layer can, for example, be a plastic film which is intended to protect the filled in filling material from ingressing liquid or gases. To achieve a sufficient venting during the filling of the paper sack, this plastic film or another gas-tight layer can be provided with the corresponding overlap. This sack does not necessarily have to comprise a coated paper layer or a coated paper layer having an overlap 22. In addition, even further perforations or air-permeable regions designed in a different manner can be provided in the material region of the plastic film outside the overlap 22.