EP1925727A2 - Machine for manufacturing tissue paper - Google Patents

Abstract

The machine (1) has counter surface (8) formed by the lateral surface of a press roll (9). The press roll has a suction zone (12) and in that lateral surface communicating holes are provided with the suction zone and have diameters less than 3.8 millimeters. The machine has a forming part for forming the tissue paper (3) from a material suspension (4).

Description

The invention relates to a machine for producing a tissue paper web according to the preamble of claim 1.

Various types of tissue paper manufacturing processes are known.

For example, the expensive TAD method or the example in the PCT / EP2005 / 050203 described method used.

In the in the PCT / EP2005 / 050203 described method, the tissue paper web is formed in the Formierpartie on a patterned screen and then dewatered in several dewatering steps, for example. Under pressure, the tissue paper web is guided throughout the dewatering on the structured screen on which it was formed. This forms a tissue paper with bulky, slightly compressed sections and compressed solid sections.

In the in the PCT / EP2005 / 050203 described method, an extended nip between the Yankee drying cylinder and formed as a shoe press unit counter surface is formed. The extended nip ensures a good transfer of the tissue paper web from the structured sieve to the Yankee drying cylinder. The extended nip merely has the task of transferring the tissue paper web from the structured sieve to the Yankee drying cylinder. It would therefore be desirable if the expensive shoe press unit could be replaced by a cheaper press roller.

However, solid shell rolls show poor transfer properties of the tissue paper web from the wire to the Yankee dryer cylinder in the attempt to create a negative pressure in the opening nip, resulting in the adhesion of the tissue paper web to the wire. Although a satisfactory transfer behavior is provided by bores in the lateral surface of the roller, the roller jackets known from the prior art with their relatively large bores of more than 3.8 mm diameter leave unacceptable shadow markings on high-quality tissue paper.

Furthermore, with the above-mentioned methods, a lower production output is usually achieved than with methods in which less high-grade, i. less fluffy and less absorbent tissue papers are produced.

Such a method is realized, for example, by a paper machine with a crescent arrangement, in which the tissue paper web is formed in the forming section on a felt and on this until the Yankee drying cylinder, by an extended nip formed between the Yankee drying cylinder and a shoe press unit to be led. In this process, the drying of the tissue paper web takes place to a substantial extent in the extended nip.

Also in this method, there is a need to replace the expensive shoe press unit by a cheaper press roller due to cost pressure. Experiments have shown in this context, however, that solid shell rolls and rolls with blind holes due to low dewatering performance are not suitable to replace the shoe press unit. Satisfactory drainage performance, however, can be provided by vacuumed press rolls.

Tissue paper manufacturers are also faced with changing requirements with regard to the quality and quantity of the tissue paper to be produced. So have to Tissue paper manufacturers sometimes provide their customers with high-quality, fluffy tissue paper in smaller quantities and, at times, less high-quality tissue paper, often in higher quantities.

The provision of manufacturing machines for both methods is costly for the tissue paper manufacturer since, on the one hand, both types of manufacturing machines are to be procured and, on the other, according to current market requirements, one or the other machine can not be used for production.

It is the object of the present invention to propose a machine that is suitable both for the production of high quality and for the production of less high quality tissue paper.

It is further the object of the present invention to propose a machine for the production of tissue paper with a nip formed by a drying cylinder and a counter surface, with the use of a shoe press unit in the nip both high-quality voluminous and less high-quality and less voluminous tissue paper and without marking and can be produced with good transfer behavior and with sufficient dry content.

The object is achieved by a machine for producing tissue paper having the features of patent claim 1.

The known machine for producing a tissue paper web has, according to the preamble of claim 1, a formed between the outer surface of a drying cylinder, in particular a Yankee drying cylinder, and a mating nip, through which the tissue paper web together with a permeable covering between the fabric and the Jacket surface is arranged guidable.

In the case of the machine according to the invention, it is additionally provided that the mating surface is formed by the lateral surface of a press roller, the press roller having a suction zone and holes communicating with the suction zone in the mantle surface having a diameter of less than 3.8 mm.

By providing a vacuumed press roll which nips with the surface of a dryer cylinder, in particular a Yankee dryer cylinder, a press configuration is proposed which does not require a shoe press unit and which is capable of good transfer in both voluminous and less bulky tissue paper to provide from the covering to the outer surface of the drying cylinder, as provided by the provision of holes, a vacuum formation in the opening nip is counteracted. The fact that the holes are evacuated, in particular for the production of less voluminous tissue paper, a sufficient dewatering performance is provided because a re-wetting at the opening nip is at least greatly reduced. Surprisingly, the adequate drainage performance can also be provided without the marking of the soft and voluminous tissue paper in particular, if the holes have a diameter of less than 3.8 mm.

The diameter of the holes according to the invention are so small that a soft and voluminous tissue paper web can not be pressed into the bores due to a strained sieve, in particular structured sieve, whereby not only a uniform crepe profile after the drying cylinder can be achieved, but also the Transfer of the voluminous and soft tissue paper web to the drying cylinder can be improved.

It is preferably provided that the machine has a forming section for forming the tissue paper web from a stock suspension and a fabric arranged in such a way that the tissue paper web in the forming section on the fabric is formed and is guided by the formed between the lateral surface of the drying cylinder and the lateral surface of the press roll nip. Thus, the tissue paper web can be guided from its formation to the nip on the same string, whereby transfer problems can not occur.

In particular, in order to increase the dry content in the production of the voluminous tissue paper, it makes sense if a drainage device is provided between the forming section and the nip.

For the production of voluminous tissue paper, it makes sense if the covering is a structured sieve, in particular a TAD sieve. The structured screen comprises recessed areas on the side facing the tissue paper web and raised areas relative to the recessed areas, the tissue paper web being formed in the recessed areas and in the raised areas of the structured screen.

The formed tissue paper web here has bulky pillow-like portions in the recessed areas of the structured screen and intermediate, lofty portions formed in the raised areas of the structured screen, the bulky portions having a higher basis weight than the less bulky portions.

The recessed areas ensure that the sections of the tissue paper web formed in the recessed areas remain protected in this during further drainage - this is because the tissue paper web remains on the structured sieve after it has been formed - and thus only slightly pressed under pressure why their voluminous structure is maintained during dehydration by pressure. Thus, typically only 25-35% of the tissue paper web is pressed under pressure.

Regarding the structure of the structured sieve and concerning the formation of the Tissue paper web on the structured sieve is placed on the PCT / EP2005 / 050203 reference, which is hereby incorporated in full in this regard in the disclosure of this application.

To produce less voluminous and less high-quality tissue paper, it makes sense if the fabric is a felt.

As tests have shown, sufficient drainage can be provided with at the same time almost complete reduction of the markings on the tissue paper web when the bores have a diameter of 3.5 mm or less, preferably 3.0 mm or less, more preferably 2.7 mm or less ,

Furthermore, it has been shown that the dewatering performance, but not the marking behavior, is influenced by the open area in the lateral surface of the press roll. In the case of the bore diameters indicated above, the best results with regard to the drainage performance are achieved if an open area of 16% to 30%, preferably 18% to 26%, particularly preferably 20% to 22%, of the total area of the lateral surface is formed by the holes becomes.

Furthermore, it has been shown that a good dewatering performance can be provided when the holes on the lateral surface of the press roll at least in sections form a regular pattern.

To improve the transfer properties of the tissue paper web from the fabric to the lateral surface of the drying cylinder, it is also useful if the lateral surface does not include the negative pressure zone communicating blind holes having a diameter of 2.7mm or less, in particular 2.4mm or less, said the blind holes can be arranged on the lateral surface at least in sections between the blind holes.

Preferably, an open area of 16% to 30%, preferably from 18% to 26%, particularly preferably from 20% to 22% of the total area of the lateral surface is formed by the holes and the blind holes together.

To further improve the drainage performance, it may also be useful if the holes and the blind holes together form a regular pattern on the lateral surface of the press roll at least in sections.

In this case, the holes or the holes and the blind holes on the lateral surface, for example. Be arranged along a family of parallel lines.

Experiments have further shown that the transfer of the tissue paper web from the fabric to the outer surface of the drying cylinder can be improved when the press roll is driven.

The dewatering device preferably comprises a dewatering section and a pressure device and is configured such that the tissue paper web can be guided along the dewatering section between the structured covering, in particular the structured screen, and another permeable covering, and by means of the printing device such pressure on the structured screen, the tissue paper web and the further permeable fabric is exercisable, that the tissue paper web is dewatered in the direction of the further permeable fabric.

The further permeable covering is preferably a felt with a sufficiently high water absorption capacity for the water pressed out of the tissue paper web. Regarding the structure of the lower clothing is on the PCT / EP2005 / 050198 referred to in full in this application.

Preferably, the compressibility (thickness change in mm when force is applied to N) of the structured sieve is smaller than the compressibility of the further permeable clothing. As a result, the voluminous structure of the tissue paper web is maintained at the pressure.

Experiments have shown that particularly good and gentle dewatering is possible when the dynamic stiffness (K) as a measure of the compressibility of the structured sieve is 3000N / mm or more.

Hard or too hard further permeable clothing would not compress the voluminous pillow-like portions of the tissue paper web at all. Due to the compressible structure of the further permeable fabric, the voluminous pillow-like sections of the tissue paper are slightly pressed and thus gently dewatered. Experiments have shown in this connection that the dynamic stiffness (K) as a measure of the compressibility of the further permeable clothing is 100000N / mm or less, preferably 90000N / mm, more preferably 70000N / mm or less.

It is likewise advantageous if the G-modulus as a measure of the elasticity of the further permeable cover is 2N / mm ² or more, preferably 4N / mm ² or more.

Furthermore, tests have shown that the water stored in the further permeable clothing, for example the felt, can be expelled more easily with a gas stream if the permeability of the further permeable clothing is not too high. It proves to be advantageous if the permeability of the further permeable clothing is 80 cfm or less, preferably 40 cfm or less, more preferably 25 cfm or less. In the areas mentioned above, rewetting of the tissue paper web is largely prevented by the further permeable covering.

The hereby on the arrangement of structured sieve, tissue paper web and further pressure applied to the permeable fabric can be caused by a gas flow. Additionally or alternatively, the pressure exerted can be effected by a mechanical pressing force.

Preferably, a gas flow can be generated by the pressure device in such a way that the dewatering of the tissue paper web firstly flows through the structured sieve, then the tissue paper web and then the further permeable covering by the gas. The dewatering of the paper web takes place in the direction of the further permeable clothing.

Additionally or optionally for gas flow through the above-mentioned arrangement, it can be provided that the pressure device comprises a press belt under tension, which is arranged such that the arrangement of structured wire, tissue paper web and further permeable clothing at least in sections along the dewatering section between the press belt and a smooth surface is feasible, wherein the press belt acts on the structured screen and the other permeable clothing is supported on the smooth surface. Here, too, a dewatering of the tissue paper web takes place in the direction of the further permeable clothing.

Preferably, the arrangement of structured sieve, tissue paper web and further permeable clothing is flowed through at least in sections in the region of the dewatering section by the gas stream, so that the dewatering takes place simultaneously by the pressing force of the press belt and the flow through the gas.

Experiments have shown that the gas flow through the tissue paper web is about 150m ³ per minute and meter length along the drainage path.

By a high tension of the press belt, the pressing force can be increased. Experiments have shown that for adequate drainage in particular the not voluminous sections of the tissue paper, the press belt is under a tension of at least 30kN / m, preferably at least 60kN / m or 80kN / m.

The press belt can in this case have a spiral structure and, for example, be designed as a so-called SiralLinkFabric. Furthermore, it is possible that the press belt has a woven structure.

In order to achieve both a good drainage of the tissue paper web by the mechanical stress of the press belt and due to the gas flow through the press belt, it makes sense if the press belt has an open area of at least 25% and a contact area of at least 10% of its total to the upper clothing has facing surface.

By increasing the contact surface of the press belt, a uniform mechanical pressure is exerted on the arrangement of structured upper clothing, tissue paper and lower clothing.

With all of the following information on contact surface and open area of the press belt satisfactory result can be achieved.

Accordingly, it is envisaged that the press belt has an open area between 75% and 85% and a contact area between 15% and 25% of its total surface facing the upper clothing.

Furthermore, it is envisaged that the press belt has an open area between 68% and 76% and a contact area between 24% and 32% of its total surface facing the upper clothing.

Very good results regarding dry content and bulkiness of the tissue paper achieved when the press belt has an open area between 51% and 62% and a contact surface between 38% and 49% of its entire upper covering area.

In particular, by forming the press belt with a woven structure, it is possible that the press belt has an open area of 50% or more and a contact area of 50% or more of its entire upper clothing facing surface. In this way, both a good gas flow through the press belt as well as a homogeneous pressing force can be provided by means of the press belt.

The smooth surface is preferably formed by the lateral surface of a roller.

The gas flow can be generated by a suction zone in a roller. In this case, the suction zone has a length in the range between 200mm and 2500mm, preferably between 800mm and 1800mm, more preferably between 1200mm and 1600mm and the negative pressure in the suction zone is between -0.2bar and -0.8bar, preferably between -0, 4bar and -0,6bar.

Optionally or additionally, the gas flow can also be generated by an overpressure hub arranged above the upper clothing.

In the latter case, the temperature of the gas flow is between 50 ° C and 180 ° C, preferably between 120 ° C and 150 ° C and the pressure is less than 0.2bar, preferably less than 0.1 bar and more preferably less than 0, 05bar. The gas can be hot air or steam.

By the dewatering process described above, it is possible for the tissue paper web to leave the dewatering section at a dry content of more than 30%.

In a further embodiment of the invention, the machine for producing a tissue paper web has a forming section, in which the tissue paper web is formed from a stock suspension on a covering. Furthermore, the machine has a nip formed between the outer surface of a drying cylinder, in particular a Yankee drying cylinder, and a mating surface, through which the tissue paper web can be guided together with the fabric, the configuration of the machine being variable such that depending on the quality For example, absorbency or tensile strength of the tissue paper to be produced, the fabric is either a three-dimensionally structured fabric, in particular a structured fabric, or a non-structured fabric, in particular a felt, wherein the counter surface is formed by the surface of a press roll comprising a suction zone, and wherein arranged in the lateral surface and communicating with the suction zone bores are provided.

Thereby, a machine is made available with which it is possible, depending on the chosen fabric either high-quality voluminous tissue paper or less high-quality and less voluminous tissue paper manufacture. Using the 3-dimensionally structured and permeable fabric, in particular the structured fabric, the tissue paper web is formed on the patterned wire and dewatered, thereby providing the tissue paper web with a high bulk weight sectional bulk structure. By using a press roll with holes for the nip formed with the drying cylinder, in particular Yankee cylinder, a good transfer of the tissue paper web from the structured wire to the drying cylinder is ensured.

The high-quality and bulky tissue paper preferably has a bulk value of 10 or more cm ³ / g, preferably 10-16 cm ³ / g and a water retention capacity of 10 g of water per g of fibers, preferably 10-16 g of water per g of fibers.

When using the non-structured permeable fabric, in particular the felt, the tissue paper web is formed on this and dewatered, whereby the Tissue paper web gets a less voluminous structure than when using the structured sieve. Such a tissue paper web can be produced with higher productivity (in tons of tissue paper per time) due to higher machine speed. By using a press roll with holes for the nip formed with the drying cylinder, in particular Yankee cylinder, a good transfer of the tissue paper web from the non-structured covering to the drying cylinder is ensured. Furthermore, during operation of the tissue paper machine with the non-structured permeable fabric, such as, for example, the felt, the press roll is sucked through the holes, whereby a sufficient drainage performance is ensured by the nip.

The lower quality and less voluminous tissue paper preferably has a bulk of less than 10 cm ³ / g, preferably from 6-9cm ³ / g and a water retention capacity of less than 10 g water per g of fibers, preferably 6-9 g of water per g fibers.

In practice, it has been found that advantageously the three-dimensionally structured and permeable fabric, in particular the structured fabric, and for the production of tissue paper with lower absorbency, the non-structured fabric, in particular the felt, is used to produce tissue with higher absorbency.

Experiments have shown that the dry content of the tissue paper web during operation with the 3-dimensionally structured and permeable fabric can not be increased by suction of the press roll, which is why in this case the press roll can be operated unswept.

Furthermore, tests have shown that when the machine is operated with the 3-dimensionally structured and permeable fabric, the transfer behavior of the tissue paper web to the drying cylinder can be increased if the press roll has a blowing zone. By the gas flow generated by the blowing zone is facilitates the lifting of the tissue paper web from press roll.

Preferably, the machine comprises a dewatering device disposed between the forming section and the nip, which is operable with respect to the nip such that the tissue paper web by the dewatering device during operation with the structured and permeable fabric to a greater extent and when operating with the non-structured and permeable clothing to a smaller extent than is drained by the nip.

Experiments with the structured sieve have shown that the dry content of the tissue paper web in this case before the nip is substantially equal to the dry content of the tissue paper web after the nip.

For further increase in production when operating the machine with the non-structured fabric, such as the felt, it may be useful if the tissue paper web is passed by the dewatering device, i. not being drained by this at all.

This means, for example, that, on the one hand, the bulky and more absorbent tissue paper is produced on the structured sieve, i. is formed and dewatered up to and including the nip formed by the lateral surface of the drying cylinder and the lateral surface of the suction press roll and this is dewatered more by the dewatering device than by the nip. In this case, the drainage is less on the nip, this is essentially the task of transferring the tissue paper from the screen to the outer surface of the drying cylinder to. As tests have shown, a good transfer is provided when the line force generated in the nip is preferably less than 120 kN / m, in particular 60-90 kN / m.

On the other hand, the less voluminous and less absorbent tissue paper is made on the felt, ie formed and up to and including the shell surface dehydrated nip formed in the drying cylinder and the outer surface of the suction press roll, this is dewatered more by the nip than by the dewatering device. Since in this case the dewatering takes place more via the nip than via the dewatering device, the nip essentially has the task of dewatering the tissue paper and transferring the tissue paper from the wire to the outer surface of the drying cylinder.

Preferably, the bores are arranged and formed such that the tissue paper web after the nip, in both modes of the machine, i. with the structured and with the non-structured covering a dry content of 31% or more, whereby when operating with the structured covering after the nip a dry content of 31-36% and when operating with the non-structured fabric after the nip a dry content of 37 -41% is achieved.

In order to reduce or even avoid markings of this tissue paper, in particular in the production of voluminous tissue paper, and at the same time to provide adequate drainage performance, it makes sense if the holes have a diameter of less than 3.8 mm, in particular less than 3.5 mm.

Fig.1

eine erfindungsgemäße Maschine in der Konfiguration zur Herstellung von hochwertigem Tissuepapier,

Fig.2

die Maschine aus Figur 1 in der Konfiguration zur Herstellung weniger hochwertigen Tissuepapiers,

Fig.3- 6

das Verfahrens zur Herstellung von Tissuepapier mit der Konfiguration der Maschine aus Figur 1,

Fig.7

die Mantelfläche einer Saugpresswalze mit erfindungsgemäßen kleinen Bohrungen und das Querprofil einer damit erzeugten Tissuepapierbahn,

Fig.8

die Mantelfläche einer Saugpresswalze mit aus dem Stand der Technik bekannten großen Bohrungen und das Querprofil einer damit erzeugten Tissuepapierbahn,

Fig. 9-11

das Verfahrens zur Herstellung von Tissuepapier mit der Konfiguration der Maschine aus Figur 2.

The invention will be explained in more detail with reference to the following schematic drawings. Show it:

Fig.1

a machine according to the invention in the configuration for the production of high-quality tissue paper,

Fig.2

the machine off FIG. 1 in the configuration for producing less high-grade tissue paper,

Fig.3- 6

the method of making tissue paper with the configuration of the machine FIG. 1 .

Figure 7

the lateral surface of a suction press roll with small bores according to the invention and the transverse profile of a tissue paper web produced therewith,

Figure 8

the lateral surface of a suction press roll with known from the prior art large holes and the cross profile of a tissue paper web thus produced,

Fig. 9-11

the method of making tissue paper with the configuration of the machine FIG. 2 ,

The FIG. 1 shows a tissue paper machine 1 with a Formierpartie 2 in which a tissue paper web 3 from a stock suspension 4 on a fabric 5, 11 is formed and formed with a between the outer surface 6 of a Yankee drying cylinder 7 and the outer surface 8 of a press roll 9 nip 10, through the the tissue paper web 3 together with the fabric 5, 11 is feasible. According to the invention, the configuration of the machine 1 is variable such that, depending on the quality, such as absorbency or tear strength of the tissue paper 3 to be produced as a covering 5, 11, either a structured sieve 5 or a felt 11 (this configuration is described in US Pat FIG. 2 shown) is used, wherein the pressure roller 9 comprises a suction zone 12 and in the lateral surface 8 of the press roller 9 communicating with the suction zone 12 holes 30 are provided.

In the in the Figures 1 and 2 As shown, in order to produce higher absorbency tissue 3, the structured fabric 5 is used, and the felt 11 is used to produce lower absorbency tissue 3 '.

When configuring the FIG. 1 the tissue paper web 3 is passed through a drainage device 34 arranged between the forming section 2 and the nip 10 and dewatered by the latter. In contrast, when in the FIG. 2 shown configuration of the machine 1, the tissue paper web 3 is not passed through the arranged between the Formierpartie 2 and the nip 10 drainage device 34 and thus not dewatered by this.

Based on FIGS. 3 to 6 Turns to the process of producing high quality, bulky and absorbent tissue paper 3 with the machine 1 configuration according to the FIG. 1 explained.

The stock suspension 4 exits from a head box 13 in such a way that it is injected into the incoming gap between a forming fabric 14 and the structured, in particular 3-dimensional structured fabric 5, whereby a tissue paper web 3 is formed.

The forming fabric 14 has a side 15 directed towards the tissue paper web 3 which is smooth relative to the side 16 of the structured fabric 5 directed towards the tissue paper web 3.

In this case, the side 16 of the structured screen 5 facing the tissue paper web 3 has recessed areas 17 and elevated areas 18 relative to the recessed areas 17, so that the tissue paper web 3 is formed in the recessed areas 17 and the raised areas 18 of the structured screen 5. The height difference between the recessed areas 17 and the raised areas 18 is preferably 0.07 mm and 0.6 mm. The area formed by the raised areas 17 is preferably 10% or more, more preferably 20% or more, and most preferably 25% to 30% of the page 16 facing the tissue paper web 3 FIG. 3 In the embodiment shown, the structured sieve 5 is designed as a TAD sieve 5.

In the in the FIG. 3 In the illustrated embodiment, the array of TAD wire 5, tissue paper web 3 and forming wire 14 is directed around a forming roll 19 and the tissue paper web 3 is substantially dewatered through the forming fabric 14 before the forming fabric 14 is removed from the tissue paper web 3 and the tissue paper web 3 on the TAD -Sieb 5 is transported.

In the FIG. 4 the structure of the tissue paper web 3 formed between the flat forming fabric 14 and the TAD wire 5 can be seen. The bulky pillow-like sections C 'formed in the recessed areas 17 of the TAD sieve 5 Tissue paper web 3 has a higher volume and a higher basis weight than the sections A 'of the tissue paper web 3 formed in the raised regions 18 of the TAD sieve 5.

The tissue paper web 3 therefore already has a 3-dimensional structure due to its formation on the structured sieve 5.

When in the FIG. 1 In the configuration shown, the tissue paper web 3 is guided between the structured sieve 5 which is arranged at the top and a further permeable clothing 20 formed as a felt 20, wherein pressure is applied to the structured sieve 5, the tissue paper web 3 and the felt 20 during the dewatering step along a dewatering path 21 is applied so that the tissue paper web 3 is dewatered in the direction of the felt 20, as indicated by the arrows 22 in the FIG. 5 is indicated. As a result, the fibers of the tissue paper web 3 are pressed against the felt 20, whereby the contacted with the felt 20 side of the tissue paper web 3 is almost flat.

As a result of the fact that the tissue paper web 3 is dewatered in the direction of the felt 20 during this dewatering step and that the tissue paper web 3 is dewatered on the structured wire 5 on which it has already been formed, the bulky portions C 'are compressed less than the portions A'. so that, as a result, the bulky structure of the sections C 'is maintained.

The pressure for dewatering the tissue paper web 3 is generated in the dewatering step at least in sections simultaneously by a gas flow and by a mechanical pressing force.

The gas stream flows through first the structured sieve 5, then the tissue paper web 3 and then the further covering formed as felt 20. The gas flow through the tissue paper web 3 is about 150m ³ per minute and meter web length.

In the present case, the gas flow is generated by a suction zone 23 in a roller 24, wherein the suction zone 23 has a length in the range between 200mm and 2500mm, preferably between 800mm and 1800mm, more preferably between 1200mm and 1600mm.

The negative pressure in the suction zone 23 is between -0.2bar and -0.8bar, preferably between -0.4bar and -0.6bar.

With regard to the execution of the dewatering step performed by mechanical pressing force and optionally or additionally with gas flow, as well as to the various configurations of devices for carrying out such a dewatering step, the PCT / EP2005 / 050198 be fully included in the disclosure of the present application.

The mechanical pressing force is generated by guiding the structured screen 5, tissue paper web 3 and felt 20 assembly on the dewatering path 21 between a tensioned press belt 25 and a smooth surface 26 in the dewatering step, the press belt 25 resting on the structured wire 5 acts and the felt 20 is supported on the smooth surface 26.

The smooth surface 26 is in this case formed by the lateral surface 26 of the roller 24.

The dewatering section 21 is essentially defined by the wrap area of the press belt 25 about the lateral surface 26 of the roller 24, wherein the wrap is determined by the distance between the two pulleys 27 and 28.

The press belt 25 is under a tension of at least 30 kN / m, preferably at least 60kN / m or 80kN / m and has an open area of at least 25% and a contact area of at least 10% of its total upper facing area.

In the concrete case, the press belt 25 is formed as a spiral link fabric and has an open area of between 51% and 62% and a contact area between 38% and 49% of its total surface facing the upper clothing.

With regard to the structure of the press belt, the PCT / EP2005 / 050198 be fully included in the disclosure of the present application.

The tissue paper web 3 leaves the dewatering section 21 with a dry content of 30% or more.

After the dewatering step, the tissue paper web 3 may be subjected to an additional drying step carried out by the indicated device 29.

Before the tissue paper web 3 passes through the nip 10, it is guided together with the structured sieve 5 around an evacuated deflection roller 32, wherein the structured sieve 5 is arranged between the tissue paper web 3 and the evacuated deflection roller 32. As a result, the structured sieve 5 moisture can be removed.

After the dewatering step carried out by the dewatering device 19, the tissue paper web 3 is guided through the nip 10 together with the structured wire 5, the tissue paper web 3 being arranged in the nip 10 between the structured wire 5 and the smooth roller surface 6 of a Yankee drying cylinder 7 (see FIG FIG. 6 ). The nip 10 is here through the Yankee drying cylinder 7 and the Saugpresswalze 9 formed.

In this case, the tissue paper web 3 lies on the side which has been formed on the flat forming fabric 15 and in the direction of which the tissue paper web 3 in the dewatering device 34 has been dewatered with a relatively large area, ie 90% or more of the total area of this side, on the lateral surface 6 of the Yankee drying cylinder 7, wherein the tissue paper web 3 rests on the other side on the structured wire 5.

The line force generated in the nip is 60-90 kN / m, so that essentially only a transfer of the tissue paper web 3 from the structured wire 5 to the Yankee drying cylinder 7 is accomplished by the nip 10.

Since the press roller 9 in its lateral surface 8 holes 30 and 31 (in FIG. 7 to recognize), a good transfer of the tissue paper web 3 is ensured. Furthermore, the press roll 9 is driven, whereby the transfer of the tissue paper web 3 from the structured wire 5 to the Yankee drying cylinder 7 is further improved.

After the nip 10, the tissue paper web 5 is passed over the heated jacket surface 6 of the Yankee drying cylinder 7 and then removed therefrom with a crep scraper (not shown). To increase the drying performance, a drying hood 33 may additionally be arranged above the Yankee drying cylinder 7 in such a way that the tissue paper web 3 is guided between the drying hood 33 and the jacket surface 6 of the Yankee drying cylinder 7.

The Figure 7a The lateral surface 8 has bores 30 and 31. The bores 30 communicate with the suction zone 12 of the press roll 9, ie are in flow communication with the suction zone 12 of the press roll 9. The bores 30 have a diameter of 2.9mm, whereby a marking of the tissue paper 3 is prevented when passing through the nip 10.

Furthermore, blind bores 31, which have a smaller diameter than the bores 30, are arranged on the lateral surface 8 between the bores 30.

The blind holes 31 have a diameter of 2.4 mm in the present embodiment. Through the blind holes 31, the marking of the tissue paper 3 is further reduced.

Through the holes 30 and the blind holes 31 together an open area of 22% of the total area of the lateral surface 8 is formed, wherein the holes 30 and the blind holes 31 together form a regular pattern on the lateral surface 8 of the press roller 9.

In the specific case, the bores 30 and the blind bores 31 are arranged on the lateral surface 8 along a family of mutually parallel lines (indicated by dashed lines).

The FIG. 7b shows the transverse profile of the tissue paper web 3 produced, as this results after creping after the circulation around the Yankee drying cylinder 7. Because the bores 30 and the blind bores 31 have a small diameter, no marking of the tissue paper 3 in the nip 10 occurs, ie the profile of the tissue paper web 3 is uniform.

In comparison, in the FIG. 8b to recognize the cross profile of a tissue paper web, as this results after creping after the circulation around the Yankee drying cylinder 7. In the FIG. 8b The tissue paper web shown was produced under the same conditions as the tissue paper web 3 with the only difference that the lateral surface 8 'of the press roll 9' used in the nip 10 has bores with a diameter of 3.8 mm or more. As you can see, the profile has elevations that correlate with the holes 30 '( FIG. 8a ).

Based on FIGS. 9 to 11 Now, the process for producing less high quality and less bulky and absorbent tissue paper 3 'with the configuration of the machine according to the FIG. 2 explained.

The stock suspension 4 emerges from the headbox 13 in such a way that it is injected into the incoming gap between the forming fabric 14 and the non-structured fabric formed as a felt 11, whereby the tissue paper web 3 'is formed.

The forming fabric 14 has a side 15 directed towards the tissue paper web 3 'which is approximately the same size as the side 34 of the felt 11 facing the tissue paper web 3'.

In the in the FIG. 9 In the illustrated embodiment, the assembly of felt 11, tissue paper web 3 'and forming fabric 14 is directed around the forming roll 19 and the tissue paper web 3' is substantially dewatered through the forming fabric 14 before the forming fabric 14 is removed from the tissue paper web 3 'and the tissue paper web 3' the felt 11 is transported on.

In the FIG. 10 the bilaterally smooth structure of the tissue paper web 3 'formed between the flat forming fabric 14 and the flat felt 11 can be seen.

In this case, the tissue paper web 3 'does not run through the dewatering device 34 arranged between the forming section 2 and the nip 10 and is therefore not dewatered by it.

The tissue paper web 3 'may be dewatered by a drying step performed by the indicated means 29.

Before the tissue paper web 3 'passes through the nip 10, it is guided together with the felt 11 around the evacuated deflection roller 32, the felt 11 being arranged between the tissue paper web 3' and the evacuated deflection roller 32. As a result, the felt 11 can be deprived of moisture so much that it can absorb sufficient moisture pressed out by the tissue paper web 3 'during the subsequent dewatering step in the nip 10.

Subsequently, the tissue paper web 3 'is guided in a dewatering step together with the felt 11 through the nip 10, wherein the tissue paper web 3' in the nip 10 between the felt 11 and the smooth roll surface 6 of the Yankee drying cylinder 7 is arranged. The nip 10 is formed here by the Yankee drying cylinder 7 and the suction press roll 9.

The line force generated in the nip is 120 kN / m or less, so that dewatering of the tissue paper web 3 'and subsequent transfer of the tissue paper web 3' from the felt 11 to the Yankee drying cylinder 7 are accomplished by the nip 10.

The FIG. 11 shows the tissue paper web 3 'passing through the nip 10.

Since the press roll 9 has bores 30 in its lateral surface which communicate with the suction zone 12 of the press roll 9, rewet in the nip opening is prevented, thereby increasing the dry content of the tissue paper web 3 '. The holes further ensure a good transfer of the tissue paper web 3 'to the Yankee drying cylinder 7. Further, the press roller 9 is driven, whereby the transfer of the tissue paper web 3 'from the felt 11 to the Yankee drying cylinder 7 is further improved.

After the nip 10, the tissue paper web 3 'is passed over the heated jacket surface 6 of the Yankee drying cylinder 7 and then removed therefrom with a crep scraper (not shown). In order to increase the drying capacity, a drying hood 33 can additionally be provided above the Yankee drying cylinder 7 be arranged so that the tissue paper web 3 'between the drying hood 33 and the outer surface 6 of the Yankee drying cylinder 7 is guided.

Since the tissue paper web 3 'has a much more compact structure than that with the configuration of the FIG. 1 formed tissue paper web 3, there is no risk in the tissue paper web 3 'that this is marked in the nip 10 due to the holes 30 and 31.

Claims (39)

Machine (1) for producing a tissue paper web (3) with a nip (10) formed between the lateral surface (6) of a drying cylinder (7), in particular a Yankee drying cylinder (7), and a counter surface (8), through which the tissue paper web (3) can be guided together with a permeable covering (5, 11) between the covering (5, 11) and the lateral surface (6),
characterized,
that the mating surface (8) by the circumferential surface (8) of a press roll (9) is formed, wherein the press roll (9) has a suction zone (12) and in the lateral surface (8) communicating with the suction zone (12) bores (30) are provided, which have a diameter of less than 3.8mm. Machine according to claim 1,
characterized ,
in that the machine has a forming section (2) for forming the tissue paper web (3) from a stock suspension (4) and a covering (5, 11) arranged in such a way that the tissue paper web (3) in the forming section (2) on the clothing (5 11) and is guided by the nip (10) formed between the jacket surface (6) of the drying cylinder (7) and the jacket surface (8) of the press roll (9). Machine according to one of claims 1 to 2,
characterized ,
in that the machine comprises a drainage device (34) arranged between the nip (10) and the forming section (2). Machine according to one of claims 1 to 3,
characterized ,
that the holes (30) have a diameter of 3.5 mm or less, preferably 3.0mm or less, more preferably 2.7mm or less. Machine according to one of claims 1 to 4,
characterized ,
that an open area of 16% to 30%, preferably from 18% to 26%, particularly preferably is formed from 20% to 22% of the total area of the lateral surface through the holes (30). Machine according to one of claims 1 to 5,
characterized ,
that the holes (30) on the lateral surface (8) of the pressing roller (9) at least in sections form a regular pattern. Machine according to one of claims 1 to 6,
characterized ,
in that the lateral surface (8) does not comprise blind bores (31) which communicate with the vacuum zone (12) and have a diameter of 2.7 mm or less, in particular 2.4 mm or less. Machine according to one of claims 1 to 7,
characterized ,
that on the lateral surface (8), the blind bores (31) are arranged at least in sections between the bores (30). Machine according to one of claims 1 to 8,
characterized,
that the bores (31) and the blind bores (30) together on the lateral surface (8) of the press roll (9) at least in sections make regular pattern. Machine according to one of claims 1 to 9,
characterized ,
in that the bores (30) and the blind bores (31) are arranged on the lateral surface (8) along a family of mutually parallel lines. Machine according to one of claims 1 to 10,
characterized,
that the press roller (9) is driven. Machine according to one of claims 1 to 11,
characterized,
that the covering (5) is a structured wire, in particular a TAD wire. Machine according to one of claims 1 to 12,
characterized ,
in that the side (16) of the structured screen (5) facing the tissue paper web (3) comprises recessed areas (17) and raised areas (18) relative to the recessed areas. Machine according to claim 13,
characterized,
that the tissue paper web (3) in the depressed and the elevated regions of the structured wire (5) is formed. Machine according to one of claims 1 to 14,
characterized ,
that in the nip (10) generated line force is less than 120kN / m. Machine according to one of claims 7 to 11,
characterized ,
that the covering (11) is a felt. A machine according to any one of claims 3 to 16,
characterized ,
in that the dewatering device (34) comprises a dewatering section (21) and a pressure device (23, 25), wherein the tissue paper web (3) can be guided along the dewatering section (21) between the structured covering (5) and a further permeable covering (29) is and by means of the printing device (23, 25) such pressure on the structured screen (5) is exercisable that the tissue paper web (3) is dewatered in the direction of the further permeable fabric (20). Machine according to one of claims 1 to 17,
characterized ,
that the drainage device (34) during operation of the machine with the structured fabric (5) to dewater the tissue paper web contributes and that the dewatering device (34) during operation of the machine with the non-structured fabric (11) not to dewater the tissue paper web (3) contributes , Machine according to one of claims 17 to 18,
characterized,
that the further permeable fabric (20) is a felt. Machine according to one of claims 17 to 19,
characterized,
that the tissue paper web (3) when pressure is applied in the dewatering device (34) in the recessed portions (17) of the structured wire is less compressible than in the increased Areas (18). Machine according to one of claims 17 to 20,
characterized ,
that the compressibility of the structured wire (5) is smaller than that of the further permeable fabric (20). Machine according to one of claims 17 to 21,
characterized ,
that the dynamic stiffness (K) as a measure of the compressibility of the structured sieve (5) is 3000N / mm or more. Machine according to one of claims 17 to 22,
characterized,
in that the dynamic stiffness (K) as a measure of the compressibility of the lower fabric (20) is 100,000N / mm or less, preferably 90000N / mm, more preferably 70000N / mm or less. Machine according to one of claims 17 to 23,
characterized,
(20) 2 N / mm ² or more, preferably 4N / mm ² or more that the G modulus, as a measure for the elasticity of the further permeable skin. Machine according to one of claims 17 to 24,
characterized ,
that the permeability of the further permeable fabric (20) 80cfm or less, preferably 40cfm or less, particularly preferably 25cfm or less. Machine according to one of claims 17 to 25,
characterized ,
in that a gas flow can be generated by the pressure device (23, 25) so that the tissue is traversed first by the structured sieve, then by the tissue paper web and then by the further permeable covering by the gas for dewatering the tissue paper web. Machine according to one of claims 17 to 26,
characterized,
that the printing device comprises a tensioned press belt (25) which is arranged such that the arrangement of structured fabric (5), in particular structured wire, tissue paper web (3) and further permeable fabric (20) at least in sections (along the dewatering section 21 ) between the press belt (25) and a smooth surface (26) is feasible, wherein the press belt (25) acts on the structured fabric (5) and the further permeable fabric (20) on the smooth surface (26) is supported. Machine according to one of claims 26 and 27,
characterized,
that the gas flow through the tissue paper web (3) is about 150m ³ per minute and meter length along the drainage path. Machine according to one of claims 27 to 28,
characterized,
that the press belt (25) is under a tension of at least 30 kN / m, preferably at least 60 kN / m or 80 kN / m. Machine according to one of claims 27 to 29,
characterized ,
that the press belt (25) has an open area of at least 25% and a contact area of at least 10% of its entire upper skin has facing surface. Machine according to claim 30,
characterized ,
that the press belt (25) facing an open area between 75% and 85% and a contact area between 15% and 25% of its entire upper skin (5) surface. Machine according to claim 30,
characterized ,
in that the press belt (25) has an open area between 68% and 76% and a contact area between 24% and 32% of its total area facing the upper clothing (5). Machine according to claim 30,
characterized ,
that the press belt (25) facing an open area between 51% and 62% and a contact area between 38% and 49% of its entire upper skin (5) surface. Machine according to one of claims 27 to 33,
characterized ,
that the smooth surface (26) is formed by the lateral surface of a roller. Machine according to claim 34,
characterized ,
in that the pressure device for generating the gas flow comprises a suction zone (23) in the roller. Machine according to claim 35,
characterized,
that the suction zone (23) has a length in the range between 200mm and 2500mm, preferably between 800mm and 1800mm, most preferably between 1200mm and 1600mm. Machine according to claim 35 or 36,
characterized ,
that the negative pressure in the suction zone (23) is between -0.2 bar and -0.8 bar, preferably between -0.4 bar and -0,6bar. Machine according to one of claims 26 to 37,
characterized,
in that the pressure device for generating the gas flow comprises an overpressure element arranged above the structured screen. Machine according to one of claims 17 to 38,
characterized,
that the tissue paper web (3) leaves the dewatering section (21) with a dry content of more than 30%.

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