WO2002042060A1

WO2002042060A1 - Method for producing a paper sack and a paper sack

Info

Publication number: WO2002042060A1
Application number: PCT/AT2001/000365
Authority: WO
Inventors: Franz Scheiber
Original assignee: Frantschach Industrial Packaging Austria Gmbh
Priority date: 2000-11-21
Filing date: 2001-11-20
Publication date: 2002-05-30

Abstract

The invention relates to a method for producing a multilayer, partially air-permeable paper sack, which has an intermediate layer (4) consisting in particular of a plastic film or coating, located between at least two paper layers (3, 8). At least the intermediate layer (4) and one paper layer (3) that is/can be attached thereto is configured with a plurality of perforations or breaks (13). According to the invention, the breaks (13) are introduced or configured so that they extend from the paper layer (3) that is/can be attached to the intermediate layer (4) and penetrate said intermediate layer in the direction of the second paper layer (8). The invention also relates to a paper sack produced in this manner, which exhibits good permeability to air, whilst achieving a corresponding impermeability to water vapour and in particular maintaining sufficient strength.

Description

METHOD FOR PRODUCING A PAPER BAG AND PAPER BAG

The present invention relates to a method for producing a multi-layer, partially air-permeable paper sack, which has an intermediate layer, at least between two paper layers, consisting in particular of a plastic film or coating, at least the intermediate layer and a paper layer connected or connectable with it a plurality of perforations or perforations is formed. The invention further relates to a paper bag which has an intermediate layer, at least between two paper layers, which consists in particular of a plastic film or coating, the intermediate layer and a paper layer connected or connectable with a plurality of perforations or perforations.

From EP-A 0 867 379 and DE-A 25 27 453, processes for the production of perforated sacks and multi-layer sacks or bags have become known, perforation taking place through all layers of a sack. Such bags are used, for example, for chunky foods in order to keep them fresh over a longer period of time, while it is not possible to absorb fine-grained or powdery materials with such bags.

A method for producing a multilayer, partially air-permeable paper sack and a paper sack of the type mentioned at the outset can be found, for example, in WO 98/57861 or US Pat. No. 5,988,881. In the case of this known paper sack, it has one on its broad sides A plurality of perforations or perforations in tape or Strip shape at least in an intermediate layer consisting of a plastic film, areas without perforations or openings being formed between the strip-like arrangement of the plurality of perforations or openings. In order to achieve a desired air permeability, due to the fact that openings are provided in the form of strips or strips, with large partial areas of the surface of the sack being formed without openings, these holes or openings must have a correspondingly large diameter, with such large dimensions or Holes or openings with diameters correspondingly reduce the strength of the paper bag produced. This is particularly disadvantageous when such paper bags are used to hold goods that are sometimes heavy, such as in the cement industry.

The aim of the present invention is, on the basis of a method for producing a multilayer, partially air-permeable paper sack and a paper sack of the type mentioned at the outset, to enable further development such that, in the case of such a multilayer paper sack, with one arranged between two paper layers, in particular made of plastic film or Coating existing intermediate layer an improvement in air permeability while increasing the water vapor density can be achieved.

To solve these problems, a method of the type mentioned is essentially characterized in that the openings starting from the one with the intermediate layer connected or connectable 'paper layers are introduced or formed by the intermediate layers in the direction of the second paper layer. The fact that, according to the invention, the openings from the paper layer connected to the intermediate layer are subsequently introduced or formed through the intermediate layer, it is ensured in particular that for the holes in the intermediate layer, which consists, for example, of a plastic film or coating, which It is crucial for the definition of a desired air permeability while maintaining the water vapor permeability that a precisely defined size of the openings can be achieved in order to be able to adapt the properties of the paper sack subsequently produced to the conditions of use. To cover the paper layer provided with perforations or perforations and the associated intermediate layer, an additional paper layer without openings can be provided on both sides of the perforated composite.

The connection between the intermediate layer, which is made in particular of plastic, and the paper layer can be essentially full-surface and / or the intermediate layer can be applied as a coating to the paper layer. Alternatively, the intermediate layer and the paper layer can, for example, be produced separately and connected to one another by means of surface or at least point adhesion.

According to a particularly preferred embodiment, it is proposed in this connection that the second paper layer, in particular after the paper sack has been filled, pressurized into contact with the perforated intermediate would be brought, which ensures that during the manufacture of the perforations when the first paper layer and the intermediate layer penetrate, a bead or edge, in particular in the region of the intermediate layer, at the edge of the respective opening due to the pressing or, in particular, provided after the paper bag has been filled Pressurization is again smoothed by means of the second paper layer, so that the desired, precisely defined size of the opening can be achieved. As a result of the additional pressurization or pressing proposed by the second paper layer according to the invention, the edge or bead formed during the production of the perforation is compressed again, which leads to a defined reduction in the clear cross section of the individual openings, so that overall a substantial increase ^'or improving the water vapor density is achievable, during the filling, a sufficient air permeability, even with small, bright Durchtrittsquer- cut of the openings is ensured.

It should be noted that the preferred proposed pressurization or pressing does not result in a direct connection of the second layer of paper to the intermediate layer, but that the pressing results in the desired shape for the openings or holes. The proposed pressurization of the second paper layer in contact with the perforated intermediate layer can take place by appropriate pressing or pressurization of the finished and in particular filled paper sack, or it can only be done by the

Weight of stacked, stacked, filled paper bags the desired compression and thus change in cross-section can be achieved. While it is essential according to the invention that the attachment or formation of the openings takes place first through the paper layer connected to the intermediate layer and subsequently through the associated intermediate layer, the paper layer also provided with perforations or openings can either be on the outside depending on the intended use or be provided on the inside facing the goods to be picked up. For a first filtering through the inner paper layer, it is proposed according to a preferred embodiment that the outer paper layer and the intermediate layer connected therewith are perforated.

In order to form the perforations or perforations, in particular in a method for producing an in particular multi-layer, partially air-permeable paper bag, which preferably has an intermediate layer, in particular consisting of a plastic film or coating, between two paper layers, at least the intermediate layer and / or an associated one or connectable paper layer is formed with a plurality of perforations or perforations, it is proposed that the perforations by a needle roller or the like. are formed, which is driven in accordance with the feed movement of the paper layer and / or the associated intermediate layer to a rotary movement. When using needle rollers, it is known to store them, for example, in a free-running manner, so that the needle roller is immediately subjected to a rotary movement by a driving movement of a web to be perforated or a material to be perforated. A disadvantage of such automatic driving of the needle roller, however, is that the need for rotary motion supply of the needle roller required drive energy must be applied by the web to be perforated itself, so that tearing or an irregular formation of the openings or perforations to be produced results. It is therefore proposed according to the invention that the needle roller is driven to a rotary movement, the peripheral speed of the needle roller being matched to the feed movement or speed of the paper layer to be perforated and the intermediate layer connected therewith, so that the shape of the needle roller is not impaired in any way breakthroughs to be produced must be feared by the entrainment of the perforation elements. With such a drive of the needle roller, taking into account the feed movement or speed of the material web to be perforated, it is in particular also possible to produce exact openings or holes with correspondingly small dimensions, it being preferably proposed that the conveying speed of the layer to be perforated and the peripheral speed the rotating needle roller can be chosen the same.

For a simple control of the drive movement of the needle roller, it is proposed according to a further preferred embodiment that the feed speed of the paper layer and / or the intermediate layer associated therewith is scanned and a control of the rotary drive of the needle roller is input.

As already indicated above, the method according to the invention aims in particular at improving the air permeability and, in the case of a subsequent pressing, at increasing or optimizing the water vapor density, so that in particular small dimensions of the openings or holes are cheap. It is therefore proposed according to a further preferred embodiment that the size, in particular the diameter, of preferably essentially circular openings between 0.05 and 1.5 mm, in particular 0.1 to 0.8 mm, is selected. In addition to the desired adjustment to the air permeability or the water vapor density, such small holes ensure that even with a high perforation density a minimal loss of strength of the resulting paper sack can be achieved due to the negligible impairment or damage to the paper or cellulose fibers, so that such correspondingly heavy goods can also be picked up.

In order to adapt to different uses of the paper sack that can be produced with the method according to the invention, it is proposed according to a further preferred embodiment that the size or shape of the perforations by choosing the penetration depth of essentially different cross-sectional shapes, in particular conically shaped needles of the needle roller is chosen. A correspondingly adapted or changed design and in particular the size or shape of the perforations or holes can thus be achieved simply by selecting the penetration depth without expensive retooling or conversion work.

In order to achieve the most uniform possible air permeability over large areas of the paper bag to be produced while maintaining the desired water vapor density and to avoid excessive loss of strength of the resulting paper bag, it is proposed according to a further preferred embodiment that a hole density of at least 100 openings / dm ² , in particular at least 1000 openings / dm ² , is selected. Particularly when using holes of correspondingly small dimensions, the desired air permeability can be made possible with the high hole density proposed according to the invention while achieving a correspondingly high water vapor density. In order, for example, to enable the air to be taken into the paper bag quickly and reliably, it is proposed according to a further preferred embodiment that the openings are formed substantially uniformly distributed over at least one broad side of the paper bag, with the formation of openings predominantly Surfaces of the paper sack to be manufactured also facilitate handling of the filled paper sack, for example in the event of subsequent stacking.

To solve the problems set out above, there is also a paper bag which, at least between two layers of paper, is made in particular of a plastic film or

Coating has an existing intermediate layer, the intermediate layer and a paper layer connected or connectable therewith being formed with a plurality of perforations or perforations, essentially characterized in that the openings start from the paper layer connected or connectable to the intermediate layer the intermediate layer is introduced or formed in the direction of the second paper layer. In this way, a sack with the desired properties, in particular with regard to air permeability and water vapor density, can be achieved. According to a preferred embodiment it is proposed that the paper layer and the intermediate layer connected or connectable have a hole density of at least 100 openings / dm ² , in particular at least 1000 openings / dm ² . Such a high hole density, with a correspondingly good air permeability and increased water vapor density, can be adapted to the purpose of use to achieve a paper bag which is correspondingly easy to handle. According to a particularly preferred embodiment, ^• hiebei proposed that the through holes are formed substantially uniformly distributed over at least one wide side of the paper bag.

In order to avoid excessive loss of strength of the paper sack to be produced, it is furthermore preferably proposed that the size, in particular the diameter, of the preferably circular openings between 0.05 and 1.5 mm, in particular 0.1 to 0.8 mm, be selected ,

According to a preferred embodiment, it is proposed that the outer paper layer and the intermediate layer connected to it are perforated. It is particularly preferably provided that the size or shape of the perforations is essentially different by the choice of the penetration depth

Cross-sectional shapes, in particular conical needles of the needle roller is selected.

The invention is explained in more detail below with the aid of exemplary embodiments illustrated in the accompanying drawing. In this show: Figure 1 is a schematic representation of an apparatus for performing the method according to the invention for producing a paper sack according to the invention.

2 shows an enlarged illustration of a partial section through a paper sack according to the invention;

3 likewise shows a partial section in a representation similar to FIG. 2 through a modified embodiment of a paper sack according to the invention; and

4 in a view similar to FIGS. 2 and 3, a detailed view for carrying out the method according to the invention for achieving holes or perforations with adjustable hole size.

In Fig. 1, 1 denotes a roll, from which a material web, schematically designated as 2, is unwound, which, as can clearly be seen in FIG. 2, consists of a paper layer 3 underneath and one connected to the paper layer 3, in particular one Plastic film or coating existing intermediate layer 4 exists. The material web 2 is fed via a feed roller or roller 5 to a needle roller 6 to form a plurality of perforations or perforations to be produced essentially over the width of the material web 2, with a pressure roller or counter roller in the area of the needle roller 6 7 is indicated. The material web 2 perforated in this way or provided with perforations is subsequently brought together via a roller 11 in the area of a subsequent station to form a multi-layer structure, which is subsequently used to produce a multi-layer paper sack, which is taken from a feed roller 9. In particular, after filling the paper sack to be produced subsequently, pressurization or pressing is carried out either by a separate device or in the case of a stack under the weight of the filled sacks, so that the protruding edge or bead 14 which arises when the perforations 13 are formed the ends 15, the stitch direction being indicated in FIG. 2 by the arrow 16, as a result of the pressurization on the paper web or layer 8 resulting in a pressing down or pressing of the edges or ends 15 of the openings 13, as this is indicated by dashed lines in FIG. 2 with 15 '. The paper web 8 shown in FIG. 2 at a distance from the layers 3 and 4 forming the material web 2 is pressed by the pressurization into contact with the intermediate layer 4, so that the upstanding edges 15, which result from the penetration of the needles of the needle roller 6 , are pressed accordingly to reduce the clear cross section of the openings 13.

By setting a desired pressing force or pressing force, besides that for adjusting the size of the holes 13 by using appropriately dimensioned needles of the needle roller 6 by pressing the edges 15 in order to achieve a corresponding air permeability while maintaining a high water vapor density Setting the clear cross section of the openings 13 can be made.

In Fig. 2, the stitch direction 16 is selected so that after completion of a paper sack by connecting two multi-ply material webs, which consist of the whole

Paper layers 3 and 8 and the intermediate layer 4 exist a paper bag, the perforated paper layer 3 lies on the inside of the paper bag to be produced.

It is further proposed that small holes or openings 13 with a diameter of less than 1.5 mm and in particular less than 0.8 mm are formed in order to achieve the desired air permeability and while minimizing the influence on the strength of the paper sack to be produced. In order to achieve such small openings with a correspondingly precise shape, it is further proposed, as indicated in FIG. 1, that the feed speed or movement of the material web 2, which consists of a paper layer 3 and the associated intermediate layer 4, is provided via a sensor 17 exists, is determined, the sensor signal being fed to a schematically indicated control 18, which in turn controls or regulates a motor 19 for the needle roller 6. The coordination of the drive or the rotational movement of the needle roller 6 to the feed speed of the multi-layer material web 2 prevents holes which are to be produced, in particular having a small diameter or small dimensions, from being produced by a relative movement between the surface of the needle roller 6 and the material web 2 to be perforated are torn or have a poorly defined outer shape.

3 shows a modified embodiment, either by reversing the arrangement of the needle roller 6 and the feed direction of the paper layer 8 or by reversing the use of the multi-layer sandwich structure consisting of the paper layer 3, the associated intermediate layer 4 and the separate paper layer 8 subsequently a paper sack is obtained in which the the outer paper layer 3 and the associated intermediate layer 4 are perforated or provided with openings 13, while the paper layer 8 facing towards the inside is designed to achieve a first filtering - without openings or holes. 3 also indicates that by pressing or pressurizing the multilayer sandwich structure or, if necessary, after manufacturing and in particular filling the paper bag by pressing the entire paper bag, the projecting ends 15 in turn reduce the free passage. section of the openings 13 are pressed.

4, the possibility of setting or selecting the size of the openings 13 to be produced is indicated using needles 20, which in particular have a conical outer circumference, in the needle roller (not shown in more detail), the depth of penetration or penetration being chosen accordingly Needle 20 in the puncture direction, again designated 16, the paper layer 3 and in particular the associated intermediate layer 4 can be formed with appropriately dimensioned openings 13. In adaptation to the desired application and / or the composition of the paper layer 3 and the intermediate layer 4 used, the choice of the penetration depth and thus the choice of the size of the holes 13 to be achieved thereby enables an adaptation to the desired air permeability and the upright position Achieve water vapor density while minimizing the loss of strength of a paper sack that will subsequently be manufactured. In particular when small openings or holes 13 are formed, damage to the Fibers of the paper layer 3 largely avoided, so that the desired strength, in particular to accommodate heavy goods, can be easily maintained.

For special purposes, a paper layer 8 can be provided on both sides of the structure consisting of the paper layer 3 and the intermediate layer 4 with the openings or holes 13, so that a total of three paper layers are provided, of which the paper layer 3 connected to the intermediate layer 4 is perforated accordingly.

Claims

Patent claims

1. A method for producing a multi-layer, partially air-permeable paper bag, which has at least between two paper layers (3, 8) an intermediate layer (4) consisting in particular of a plastic film or coating, at least the intermediate layer (4) and an associated one or connectable paper layer (3) with a plurality of perforations or openings (13), characterized in that the openings (13) starting from the paper layer (3) connected or connectable to the intermediate layer (4) the intermediate layers are introduced or formed in the direction of the second paper layer (8).

2. The method according to claim 1, characterized in that the second paper layer (8) is brought into contact with the perforated intermediate layer (4) in particular after the filling of the paper bag under pressure.

3. The method according to claim 1 or 2, characterized in that the outer paper layer (3) and the associated intermediate layer (4) are perforated.

4. The method according to any one of claims 1 to 3, characterized in that the perforations (13) are formed by a needle roller (6) or the like, which according to the feed movement of the paper layer (3) and the associated or connectable intermediate layer ( 4) is driven to rotate.

5. The method according to claim 4, characterized in that the feed speed of the paper layer (3) and thus Connected or connectable intermediate layer (4) is scanned and a control of the rotary drive (19) of the needle roller (6) is entered.

6. The method according to any one of claims 1 to 5, characterized in that the size, in particular the diameter, of the preferably substantially circular openings (13) between 0.05 and 1.5 mm, in particular 0.1 to 0.8 mm , is selected.

7. The method according to claim 6, characterized in that the size or shape of the perforations (13) is selected by choosing the penetration depth of essentially different cross-sectional shapes, in particular conical needles (20) of the needle roller (6) ,

8. The method according to any one of claims 1 to 7, characterized in that a hole density of at least 100 openings / dm ² , in particular at least 1000 openings / dm ² , is selected.

9. The method according to any one of claims 1 to 8, characterized in that the openings (13) are formed substantially uniformly distributed at least over a broad side of the paper bag.

10. A method for producing an in particular multi-layer, partially air-permeable paper bag, which preferably has an intermediate layer (4), in particular consisting of a plastic film or coating, between two paper layers (3, 8), at least the intermediate layer (4) and / or a paper layer (3) connected or connectable with a plurality of perforated tion or perforations (13) is formed, characterized in that the perforations (13) are formed by a needle roller (6) or the like, which according to the feed movement of the paper layer (3) and / or the associated or connectable intermediate layer (4) is driven to rotate.

11. The method according to claim 10, characterized in that the feed speed of the paper layer (3) and / or the associated or connectable intermediate layer (4) is scanned and a control of the rotary drive (19) of the needle roller (6) is entered.

12. The method according to claim 10 or 11, characterized in that the conveying speed of the layer to be perforated (3, 4) and the peripheral speed of the rotating needle roller (6) are chosen to be the same.

13. The method according to claim 10, 11 or 12, characterized in that the size, in particular the diameter, of the preferably substantially circular openings (13) between 0.05 and 1.5 mm, in particular 0.1 to 0, 8 mm.

14. Paper bag, which has an intermediate layer, at least between two paper layers (3, 8), in particular consisting of a plastic film or coating, the intermediate layer (4) and a paper layer (3) connected or connectable with a plurality of perforations or Openings (13) is formed, characterized in that the openings (13) starting from the paper layer connected or connectable to the intermediate layer (4) (3) are introduced or formed through the intermediate layer (4) in the direction of the second paper layer (8).

15. Paper bag according to claim 14, characterized in that the paper layer (3) and the associated or connectable intermediate layer (4) have a hole density of at least 100 openings / dm ² , in particular at least 1000 openings / dm ² .

16. Paper bag according to claim 14 or 15, characterized in that the openings (13) are formed substantially uniformly distributed at least over the broad side of the paper bag.

17. Paper bag according to claim 14, 15 or 16, characterized in that the size, in particular the diameter, of the preferably substantially circular openings (13) between 0.05 and 1.5 mm, in particular 0.1 to 0.8 mm is selected.

18. Paper bag according to one of claims 14 to 17, characterized in that the outer paper layer (3) and the associated intermediate layer (4) are perforated.

19. Paper bag according to one of claims 14 to 18, characterized in that the size or shape of the openings (13) is selected by choosing the puncture depth of substantially different cross-sectional shapes, in particular conical needles (20) of the needle roller (6) ,