EP2186939A2 - Method for producing bag paper, bag paper and paper bag - Google Patents

Abstract

The method comprises producing a bag paper web (2) in a paper machine (3), which comprises a headbox on a sieve, a drainage in a press and a dryer in a drying section, and then winding the bag paper web using a coil (8). The bag paper web is treated in an extended nip calender at the end or after the paper machine, and is treated before winding in the extended nip calender. The bag paper web compresses around 5% in the running direction with a dry content of 40-80%. The extended nip calender impinges with a flexible cover over a shoe roller or a flexible rotating belt (14) impinges the web. The method comprises producing a bag paper web (2) in a paper machine (3), which comprises a headbox on a sieve, a drainage in a press and a dryer in a drying section, and then winding the bag paper web using a coil (8). The bag paper web is treated in an extended nip calender at the end or after the paper machine, and is treated before winding in the extended nip calender. The bag paper web compresses around 5% in the running direction with a dry content of 40-80%. The extended nip calender impinges with a flexible cover over a shoe roller or a flexible rotating belt (14) impinges the web with a pressing pressure. A first web side lying on a smoothed and heated roller with the extended nip calender is smoothed to a pulse-per-second (PPS) value of below 7 mu m. The first web side lying on a smoothed and heated roller with the extended nip calender is smoothed to a pulse-per-second (PPS) value ratio of over 1.4 from in running direction before the extended nip calender to in running direction of the web behind the extended nip calender. The web with the extended nip calender is compressed to maximum 15% from in running direction before the extended nip calender to in running direction of the web behind the extended nip calender. The extended nip calender impinges the uncompressed bag paper with a maximum pressing pressure of 5-20 MPa over a flexible counter pressure element and the compressed bag paper with a pressing pressure of 2-5 MPa. The pressing pressure of the extended nip calender is adjusted, so that Gurley-porosity of the compressed bag paper remains to a value below 7 seconds and Gurley-porosity of the uncompressed bag paper remains to a value below 30 seconds. The extended nip calender is operated, so that the value of the Gurley-porosity of the web in the extended nip calender increases to maximum 50%. The surface of the heated roller has a temperature of 180-220[deg] C. The amplitude of the heating is reversely adapted to the web width. The web before the extended nip calender is moistened to uniform valve of 5-12% over the web width. The web is dried in the extended nip calender with the drying capacity, which brings a drying cylinder of same building type in the drying section at same position as the extended nip calender. Independent claims are included for: (1) compressed and uncompressed bag paper; and (2) a paper bag.

Description

The invention relates to a method for producing compressed or unsteamed sack paper in which the web is produced in a paper machine, which is wound up the head box on a sieve, the dewatering in a press and the drying in a dryer section, and then by means of a winding ,

The invention further relates to a sack paper produced by the method and a paper sack made of the sack paper produced by the method.

Sack paper, which is part of the Kraft papers, is usually made of long-fiber softwood kraft pulp with a maximum waste paper content of 20%. It is used to make paper sacks to hold, for example, cement, minerals or food. The basis weight of the sack paper is 60 to 120 g / m ² . The produced bags are usually 1-3-ply and have a predominant capacity of 25 kg.

The production machines used today allow speeds up to 1000 m / min, because higher headbox speeds are not yet overcome by the flow characteristics of the long fibers. In a press, which may well include a shoe roll, the web is drained. It is then passed over drying cylinders until they can be wound up.

Sack papers are partially compressed in order to have a better elongation behavior (for example during the filling process). There are several known methods. The greatest importance here is the so-called Clupak method, in which the web has a stretching and again relaxing elastic band is passed. In this compression, one speaks often of a creping process.

Nowadays, sack papers are usually not smoothed, since with the known smoothing methods, the smoothness can only be improved at the expense of porosity. This property of high air permeability, measured e.g. Gurley porosity (ISO 5636-5, TAPPI T 460), however, is decisive for the fillability of the sacks: if the air can not be displaced quickly enough, the sack can not be filled with the material quickly or the air will overflow the filling opening and takes away the contents or at least its fine components.

On the other hand, it would certainly be desirable to achieve a smoother surface, at least on one side, without accepting the described disadvantages, since this would allow the printability with regard to print quality and ink consumption to be optimized. This is particularly important because in the meantime, the sack package is used as a sales package.

It is the object of the invention to provide a way to produce a particularly high quality and good printable sack paper.

The object is achieved in relation to the manufacturing method in that the web is treated at the end or after the dryer section in a nip calender.

Attempts to straighten a sack paper so that it can be printed well have never led to satisfactory results. Only a Breitnipkalander brought unexpectedly the desired results. nip calender have in their contact zone (nip), in which the web is treated, a longer exposure time of high temperatures, but lower pressures. All this means that although the melted surface leveled, the porosity is not deteriorated in an undue manner.

It is advantageous if the web is treated in a nip calender prior to winding. The printable sack paper is then smoothed online in a manufacturing machine. The web does not cool as it would automatically do after a rewind before it is smoothed. It goes through the broad nip approximately to the temperature that it has built up in the dryer section. This has a positive influence on the surface finish of the web and also on the energy balance of the manufacturing machine.

Advantageously, the web is compressed at a dry content of 40-80% by at least 5% in the direction of travel. Such a sack paper has a significantly greater extensibility and a better tear resistance. In particular, when filling and transporting paper bags tearing is largely avoidable in a paper bag produced according to this method. The compression should be done in the specified moisture condition, since the compression (or creping called) otherwise does not remain stable.

It is favorable if, with the broad nip calender, a first web side resting against a smooth and heated roll is smoothed to a PPS 10S value (DIN ISO 8791-4) of less than 7 μm. In general, it is sufficient if the outwardly facing side of the bag manufacturing has a higher smoothness. This web page can get a relatively high quality print without any problems. Paper sacks that are printed from the outside have a high advertising impact afterwards.

Particularly preferably, the offset or flexographic printing process is used.

Preferably, with the broad nip calender, a first web side resting against a smooth and heated roll is smoothed to a PPS 10S value ratio from in front of the nip calender in the direction of travel behind the nip calender of more than 1.4. Such a smoothing increase is usually sufficient to allow uniform printability. One can intentionally make the one-sided smoothing, wherein the change in the surface quality of the not preferred smoothed side is less than on the preferred smoothed side and compared to the value before smoothing the roughness PPS 10S changed only by a maximum of 10% and the roughness Bendtsen only by a maximum of 15%.

Advantageously, it is ensured that the web is compacted with the Breitnipkalander of in the direction of the Breitnipkalander to the direction of the web behind the Breitnipkalander by a maximum of 15%. Such a measure serves to maintain elasticity. The volume-saving smoothing of sack paper preserves a relatively large proportion of air in the fiber structure and prevents rupture of the fiber network.

Preferably, the nip calender acts on a flexible counter-pressure element un-sacked bag paper with a maximum pressing pressure of 3 to 15 MPa, preferably 5 to 10 MPa, and compressed sack paper with a compacting pressure of 1 to 10 MPa, preferably 2 to 5 MPa. The speech here is of compressive stress, for example, in the middle of the nip length in the web running direction. These compressive stresses are very moderate compared to conventional smoothing pressures. The web is only slightly compressed and retains the necessary porosity.

Advantageously, it is ensured that the extended nip calender acts on the web with a pressing pressure via a shoe roll with a flexible jacket or a flexible band. Such shoe rollers are known and represent a mature technique in the field of other types of paper. The nip length can be varied via the shoe geometry.

Preferably, the pressing pressure of the nip calender is adjusted so that the Gurley porosity (TAPPI T 460m49) of the compressed sack paper web remains below 7 seconds and the uncompressed sack paper web remains below 30 seconds. An exact adjustment of the pressing pressure can be done so that one measures the porosity of the paper web in the finished state or after the Breitnipkalander (possibly online). If the porosity measured according to Gurley, for example, exceeds the value of 7 seconds for a compressed sack paper web, the pressing pressure is reduced. A Gurley value below 7 sec allows filling of paper sacks, for example with cement without much dust.

It is favorable if the nip calender is operated so that the value of the Gurley porosity (TAPPI T 460m49) of the web in the nip calender increases by a maximum of 50%. It has been found that a halving of the output air permeability just barely allowed for the later use - for example, the production of paper sacks - is. The suitable Anpressduck or the appropriate surface temperature of the heating roller can be determined in a few experiments.

In such experiments, it has been found that the surface of the heated roll preferably has a temperature of 150 to 250 ° C, preferably 180 to 220 ° C. In this temperature range, the best sack paper for later printability has been smoothed. Particularly preferably, the width of the heating is adapted to the web width or vice versa. The heating of the heating roller can be done from the inside or from the outside, for example, inductive. Zone-adjustable sectors are known for such heating methods. In order to protect a possibly existing coat or a possibly present band of a shoe roll or generally the flexible cooperating with the heating roller counter-pressure element from overheating by the relatively hot heat roller, the transported away from the web heat in the Heizenergiezufuhr can be limited to the web width , Conversely, it is alternatively possible to tailor the web by edge trimming to the width of the heat-emitting area of the heating roller.

The smoothness result in the nip can preferably be improved by moistening the web before it enters the nip calender to a uniform width of between 5 and 12% over the web width. The closer the moistening device is positioned in front of the nip, the more the compaction of the web is limited to the surface of the web. This means that the middle layers have to be pressed less for a good smoothness result, which in turn causes the positive volume retention. Numerous publications describe what is known as Moisture Gradient Calendering, which surprisingly can also be used in sack paper in this process. Depending on the substance composition, steam (the less water, but more heat) or nozzle moistener (with higher moisture input) can be used. It is crucial that the preferred moisture cross profile is particularly uniform, since moisture differences across the width tend to degrade the quality of the sack paper.

Preferably, the web is dried in the nip calender with the drying performance, the at least one drying cylinder of the same type as in the preceding drying section at the same position as the Breitnipkalander would apply. If the nip calender has the drying capacity like a preceding drying cylinder, it is possible to convert existing sack paper machines, for example, by replacing the last drying cylinder with a nip calender. The paper web does not have to be wound up in a disadvantageously wet way, and the new arrangement makes it possible to use the method according to the invention of producing a particularly easy-to-print sack paper.

The invention also claims its protection to a compressed bag paper produced by the process which has a PPS 10S value (DIN ISO 8791-4) of less than 7 μm, a density of less than 0.80 g / cm ³ and a Gurley porosity ( TAPPI T 460m49) under 7 sec. This sack paper has excellent and over the prior art significantly increased properties for the production of paper sacks.

Similarly, the invention claims its protection also to a produced by the process undrilled bag paper, which has a PPS 10S value (DIN ISO 8791-4) of less than 5 microns, a density of less than 0.80 g / cm ³ and a Gurley porosity (TAPPI T 460m49) under 30 sec

Furthermore, a protection claim is directed to a paper bag, which is formed or sewn from a prepared according to the method of any one of claims 1 to 14 and trimmed bag paper.

Particularly preferably, the paper bag has a plurality of sack paper layers. This makes it particularly stable, without preventing air leakage during filling.

With particular advantage, the sack paper is printed on the smoothed side before sack formation in the offset or flexographic printing process. These printing methods are particularly suitable for applying labels and graphics to the sack paper produced in the process. Due to the achieved smoothness the imprint becomes clear and clear and in bright colors and the color consumption is limited.

The invention will be explained in more detail below with reference to exemplary embodiments with reference to the drawing. In this, the single figure shows a schematic representation of a Breitnipkalanders 12 within a device for producing a sack paper web first

An apparatus shown in the figure for producing a sack paper web 1 is used to produce a F 2. The sack paper web 2 comes from a paper machine 3, the at least one headbox for applying the sack paper web 2, a press in which the sack paper web is dewatered, and a dryer section in which the sack paper web is dried over drying cylinders. It is only schematically shown as a box 3 for simplicity. It is also possible to unwind the sack paper web 2 from a supply roll, for example a jumbo roll.

The sack paper web 2 passes after said headbox, said press and at least part of said dryer section (all summarized in box 3) first a compression device 4, in which the sack paper web is compressed by about 5% in the web running direction 9. A known method works by means of a rubber-elastic masking tape 6, which is guided over guide rollers 7, a path parallel to the sack paper web 2 on the surface of a drying cylinder 5 runs (Clupak method).

By adjusting the elongation and springback of the masking tape 6, the sack paper web 2 is compressed or at least micro-compressed.

If you want to produce ungestaesses bag paper, the upsetting device 4 can be bypassed in a manner not shown.

In the direction of travel 9 behind the compression device 4, optionally further drying cylinders and following a moistening device 10 are arranged, which applies steam or water spray 11 to the first side 2a of the sack paper web 2.

In the web running direction 9 behind the moistening device 10, a Breitnipkalander 12 is arranged, which is also referred to as "shoe calender". Behind this follows a reel 8, where the finished sack paper web 2 is wound into rolls.

The Breitnipkalander 12 has as a flexible counter-pressure element 34 to the heating roller 15, a shoe roll 13 with a circumferential jacket 14. The jacket 14 cooperates with a heating roller 15 and forms a broad nip 16, in which the sack paper web 2 is calendered, that is, subjected to a certain pressure and with an elevated temperature. In this case, the voltage applied to the heating roller 15 web page 2a is much more smooth than the other web page 2b.

The heat roller 15 has a plurality of peripheral bores 17 through which a heat transfer medium, for example, oil or steam or water spray, can be guided around the surface of the heat roller 15 having a surface temperature in the range of 150 to 250 ° C, preferably 180 to 220 ° C, to provide. Of course, other possibilities can be used instead of the peripheral bores 17. to heat the surface of the heating roller 15, for example, an induction heater, not shown, or infrared heating.

The heaters may be adjustable in zones according to the web width.

The shoe roll 13 has a contact shoe 18, which is arranged stationary. In order to close the wide nip 16, the heating roller 15 is moved in the direction of a double arrow 19, wherein the jacket 14 is supported by a pressure surface 20 of the pressure shoe 18. The pressure surface 20 has in the present embodiment, a shape that is adapted to the curvature of the heating roller 15 taking into account the thickness of the jacket 14. But this is not absolutely necessary. Of course, the closing process is also conceivable vice versa with fixed heating roller 15 and moving shoe roll 13.

Furthermore, an arrangement is conceivable in which the side to be smoothed is located below. In this case, all components and functions also change from top to bottom and vice versa. In this case, the moisture application could be done equally with steam or water, a cooling roller 22 could be rather dispensed with when using water.

The extended nip 16 has a length in the web running direction 9 in the range of 30 to 400 mm. At a speed of the sack paper web 2 in the range of 400 to 2,500 m / min, the sack paper web 2 thus requires about 0.8 to 50 ms, but preferably more than 5 ms, in order to pass through the extended nip 16.

It is now with pressure means not shown in detail a compressive stress in the extended nip 16, which in a compressed sack paper a maximum pressing pressure of 3 to 15 MPa, preferably 5 to 10 MPa, and in compressed sack paper a pressing pressure of 1 to 10 MPa, preferably 2 to 5 MPa provides. This compressive stress acts, for example, approximately in the middle of the broad nip in the web running direction 9. From the entry into the broad nip, the compressive stress increases, namely a maximum of 2 MPa per mm. In other words, the gradient of the compressive stress is limited.

Previously, when passing a sack paper web through a "normal" calender whose nip was formed by two opposing rolls, it was found that the sack paper lost its desired porosity. In the embodiment according to the figure, the pressing pressure of the broad nip calender is adjusted so that the Gurley porosity (TAPPI T 460m49) of the sack paper web remains at a value below 7 sec. A precise adjustment of the pressing pressure can be done so that one measures the porosity of the sack paper web in the finished state. If the porosity measured according to Gurley exceeds the value of 7 seconds, the pressing pressure is reduced.

In the illustrated embodiment, the moistening device 10 is arranged about 0.3 to 1.5 m before entering the broad nip 16. The smoothness result can thereby be increased and the compaction of the sack paper web reduced.

In addition, in the illustrated embodiment, only one Breitnipkalander 12 is installed and it is only one side 2a smoothed (web top), as is usually only useful in sack papers. If a two-sided smoothing is desired, then a second Breitnipkalander must be arranged in the direction behind the illustrated extended nip 16, in which the heating roller is arranged in the lower position. In order to determine the technical parameters of this invention, experiments were carried out in a laboratory.

Immediately before the nip nip 12 and before moistening 10, the web moisture was 5 to 12% and the web temperature 50 to 90 ° C, preferably 60 to 70 ° C. The cover that touched the opposite side was as soft as possible, for example, mostly made of PU (polyurethane) with a hardness below 60 Sh (D), preferably below 95 Sh (A). The nip length in the web running direction 9 was preferably 60 to 120 mm, or the residence time typically less than 20 ms, preferably 5 to 15 ms, preferably about 10 ms. The heating roller 15 had a surface temperature of preferably about 200 ° C. A combination of inductive external heating with internal heating roller was applicable. The compressive stress in undamped sack paper was 3 to 15 MPa, preferably 5 to 10 MPa, with compressed sack paper 1 to 10 MPa, preferably 2 to 5 MPa. Preferably, a version with vapor deposition of the side to be smoothed should be selected immediately before the nip, preferably 0.3 to 1.5 m before Nipeinlauf, it should be the steam blast box preferably 0.5 to 3 g / m ² supplied. Depending on the efficiency of the steam transfer, which is mainly determined by the web temperature, the sack paper web absorbs up to 80% of the supplied amount of steam. It was recognized in the experiments that, after drying and prior to vapor deposition, a cooling cylinder 22 is usefully to be arranged if the web temperature without the cooling cylinder before the nip is more than about 70 ° C. In an offline process, this chill roll will therefore usually not be required.

The paper produced in this way had the following characteristics: The PPS 10S roughness (ISO 8791-4, Tappi T555) without creping was on the side to be smoothed of approx. 8.5 μm before or without nip calender 12 up to 3.5 The target range was 4 to 5 μm or an improvement to 45 to 60% of the initial value. At the same time, and that is the peculiarity of the shoe calender, the porosity only increased from 17 to max. 26 sec, in the PPS target range to approx. 20 sec, so it increased to approx. 115 to 120% of the initial value. The maximum permitted value is approx. 40 s and was thus clearly undercut. In addition, in the same case, the Bendtsen roughness (DIN ISO 5636 / 3-8791 / 2, DIN 53108/53120) of about 700 ml / min was reduced to a minimum of 130 ml / min, in the target range of 4 to 5 microns PPS roughness to 200 to 280 ml / min, ie to 25 to 40% of the initial value. At the same time, the density of 0.70 g / cm ^{3 increased} to a peak value of 0.80 g / cm ³ , in the target range 0.75 g / cm ³ to 0.78 g / cm ³ , ie increased in the target area only by max. 15%.

In the case of compressed varieties, the PPS roughness of about 9 μm on the side to be smoothed before or without calender was reduced to a target range of 5 to 6 μm, corresponding to an improvement to 55 to 65% of the initial value. At the same time, the porosity only increased from 4.9 s to 5.2 to 5.8 s, ie only increased to max. 115% of the initial value. The Bendtsen roughness was reduced from about 780 ml / min in the target range of the PPS roughness to 300 to 380 ml / min, ie to 35 to 50% of the initial value. At the same time, the density of about 0.70 g / cm ³ in the target area increased to 0.73 g / cm ³ to 0.75 g / cm ³ , ie by max. 10% on.

Due to the production of different grades or area weights, a different web width occurred at the end of the dryer section due to different shrinkage. This can be taken into account in two ways, either by edge trimming, so that the working width of the wide nip calender 12 is set to the smallest web width or slightly below it. The non-calendered web edges must then be cut off after the nip calender 12 and before the winding 8 in a marginal cutting device 21. The other Varante is passing through the variable web calender. In this case, the widest sack paper web 2 is narrower than the working width of the calender.

Then, the non-covered by the sack paper edge areas of the elastic cover must be protected from overheating by contact with the heated roller 15. A PU jacket 14 may be e.g. only heated to 100 ° C (measured before Nipeintritt). Remedy can be provided only by cooling the jacket 14 of the shoe roll 13, e.g. by spraying an air-water mixture. Furthermore, an unillustrated temperature control and temperature control can be used, in particular also so that a possible cooling roller 22 after the dryer section only when needed (exceeding a permissible jacket temperature) must be operated, which reduces the noise and saves energy. Furthermore, in the case of edge cooling of the shell 14, it may be useful to limit the surface temperature of the heating roller to (measured before the nip) 170 ° C or less, if a larger temperature difference from the edge cooling can not be overcome. If the web width is to be variable, the heating zone width of the thermo roll can also be made variable and adapted accordingly, e.g. by not shown, inner, sliding insulating sleeves in peripheral bores 17th

The nip calender 12 can also be used to increase the dry content of the sack paper web 2. This is particularly attractive when an existing device for producing a sack paper web 1 to be rebuilt and space must be created for the installation of Breitnipkalanders. The Breitnipkalander can then be operated so that it can replace 1 to 4, preferably 1 to 2 drying cylinder 5 with its drying capacity.

LIST OF REFERENCE NUMBERS

1

Device for producing a sack paper web

2

Sack paper web

2a

first track side

2 B

second track side

3

Paper machine (headbox, press, drying cylinder)

4

upsetting device

5

drying cylinders

6

masking tape

7

idlers

8th

rewind

9

Web direction

10

humidifying

11

Steam or water spray

12

nip calender

13

shoe roll

14

coat

15

heating roller

16

nip

17

peripheral drilling

18

shoe

19

Direction of movement (double arrow)

20

pressure surface

21

Edge cutter

22

chill roll

23

flexible counterpressure element

Claims (19)

A method of making upset or un-sacked sack paper, wherein the sack paper web (2) is made in a paper machine (3) comprising headboxing on a wire, dewatering in a press and drying in a dryer section, and then by means of a rewind (8) is wound, characterized in that the sack paper web (2) at the end or after the paper machine (3) in a Breitnipkalander (12) is treated. A method according to claim 1, characterized in that the sack paper web (2) is treated prior to winding in a Breitnipkalander. A method according to claim 1 or 2, characterized in that the sack paper web (2) at a dry content of 40 - 80% by at least 5% in the direction of compression. Method according to one of claims 1 to 3, characterized in that with the Breitnipkalander (12) a first on a smooth and heated roller adjacent web page (2a) to a PPS 10S value (DIN ISO 8791-4) smoothed below 7 microns becomes. Method according to one of claims 1 to 4, characterized in that the Breitnipkalander a first on a smooth and heated heating roller (15) adjacent web page (2a) to a PPS 10S value ratio of in the direction before the Breitnipkalander (12) in the direction of the web (2) behind the Breitnipkalander (12) is smoothed by over 1.4. Method according to one of claims 1 to 5, characterized in that the web (2) with the Breitnipkalander (12) from in the direction of the Breitnipkalander (12) in the running direction of the web (2) behind the Breitnipkalander (12) by a maximum of 15 % is compressed. Method according to one of claims 1 to 6, characterized in that the Breitnipkalander (12) via a flexible counter-pressure element (23) ungestaess Sackpapier with a maximum pressing pressure of 3 to 15 MPa, preferably 5 to 10 MPa, and compressed bag paper with a pressure of 1 to 10 MPa, preferably 2 to 5 MPa, applied. Method according to one of claims 1 to 7, characterized in that the Breitnipkalander (12) acts on the web via a shoe roll with a flexible jacket (14) or a flexible circulating belt with a pressing pressure. A method according to any one of claims 7 to 8, characterized in that the pressing pressure of the Breitnipkalanders (12) is adjusted so that the Gurley porosity (TAPPI T 460m49) of the compressed sack paper web (2) to a value below 7 sec and the non-compressed sack paper web (2) remains at a value below 30 sec. Method according to one of Claims 1 to 9, characterized in that the nip calender (12) is operated such that the value of the Gurley porosity (TAPPI T 460m49) of the web (2) in the nip calender (12) increases by a maximum of 50%. A method according to claim 4, characterized in that the surface of the heated roller (15) has a temperature of 150 to 250 ° C, preferably 180 to 220 ° C. A method according to claim 4 or 11, characterized in that the width of the heating is adapted to the web width or vice versa. A method according to any one of claims 1 to 12, characterized in that the web is moistened in front of the nip calender (12) to a uniform width over the web value between 5 and 12%. A method according to any one of claims 1 to 13, characterized in that the web (2) is dried in the nip calender (12) with the drying performance comprising at least one drying cylinder of the same type as in the preceding drying section (3, 5) at the same position as the Would apply Breitnipkalander (12). Crushed sack paper produced by the process according to any one of claims 1 to 14, characterized in that it has a PPS 10S value (DIN ISO 8791-4) of less than 7 μm, a density of less than 0.80 g / cm ³ and has a Gurley porosity (TAPPI T 460m49) below 7 sec. Unstopped sack paper produced by the process according to any one of claims 1 to 14, characterized in that it has a PPS 10S value (DIN ISO 8791-4) of less than 5 μm, a density of less than 0.80 g / cm ³ and a Gurley porosity (TAPPI T 460m49) less than 30 sec. Paper bag, characterized in that it is glued or sewn from a sack paper produced and cut to size according to the method of any one of claims 1 to 14. Paper bag according to claim 17, characterized in that the paper bag has a plurality of sack paper layers. Paper bag according to claim 17 or 18, characterized in that the sack paper is printed on the smoothed side before sack formation in the offset or flexographic printing process.

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