SE1950671A1 - A machine and a method for making tissue paper - Google Patents

Abstract

The invention relates to a machine (1) for making tissue paper which machine (1) comprises a Yankee (2) with a shell (3) which has an outer surface (4). The Yankee (2) is rotatable about an axis of rotation (A) in a direction of rotation (R). The machine also comprises an imprinting fabric (5) that forms a continuous loop and is arranged to carry a fibrous web (W) to the Yankee (2). The web-contacting side (6) of the imprinting fabric (5) has a texture such that a three-dimensional pattern can be imprinted into the fibrous web (5). A press roll (7) is arranged inside the loop of the imprinting fabric (5) and forms a non-dewatering transfer nip (TN) against the Yankee (2). A creping doctor (8) acts against the outer surface (4) of the shell (3) to crepe a dried fibrous web (W) from the outer surface (4) of the shell (3). A coating device (10) which, in the direction of rotation (R) of the Yankee (2), is located after the creping doctor (8) but before the transfer nip is arranged to apply a liquid coating onto the outer surface (4) of the shell (3). The shell (3) is a non-metallized steel shell. The invention also relates to a method of making tissue paper.

Description

A MACHINE AND A METHOD FOR MAKING TISSUE PAPER FIELD OF THE INVENTION The present invention relates to a machine for making tissue paper in which a Yankeedrying cylinder with a steel shell is used. The invention also relates to a method of making tissue paper in which method the inventive machine is used.

BACKGROUND OF THE INVENTION A machine for making tissue paper typically includes a Yankee drying cylinder Which,during operation, is heated intemally by hot steam. In the following, the term “Yankee”will be used for Yankee drying cylinders. A wet fibrous web that is transferred to theYankee is dried on the outer surface, the “drying surface” of the Yankee, andsubsequently creped from the drying surface (the outer surface) of the Yankee by acreping doctor. During the twentieth century, Yankees were usually made of cast ironbut in recent years, Yankees have been made in Welded steel. A steel Yankee weighsless than a cast iron Yankee having the same required strength and steel Yankees arethus seen as advantageous. An example of a steel Yankee is disclosed in EP 2126203Bl. As mentioned above, a creping doctor is used to crepe the ready-dried fibrous webfrom the surface of the Yankee. In practice, this means that the surface of the Yankeewill be subjected to pressure from the doctor blade. A cast Yankee has a surface with arelatively high hardness since cast iron may typically have an HB hardness (i.e. Brinellhardness) of 220 - 260. For this reason, the surface is not so easily worn out by contactwith the doctor blade that is pressed against its surface. However, experience hasshowed that even Yankees made of cast iron are subjected to a considerable degree ofwear. For this reason, it has long been a practice to metallize the surface of Yankees inorder to obtain a harder surface. In the context of this patent application, “to metallize”and “metallization” refer to a process in which the outer surface (the drying surface) ofthe Yankee is coated with a hard layer which may be based on an element or an alloy ora mixture of metal powder and at least one carbide or nitride or possibly other elements,or a metal matrix containing at least one carbide or nitride or possibly other elements.The coating may typically be applied to the surface of the Yankee by spraying. Anexample of this technology is disclosed in US patent No. 4,064,608. Other examples aredisclosed in US patent No. 5,l23,l52; US patent No. 6,l7l,657 and US patent No.l0,240,29l. It should be noted that many different compositions for the hard layer have been proposed. For example, the hard layer may be an iron alloy containing from about20 to about 47 Weight per cent chromium, about 2.5 to about 6.5 weight per cent boron,about 1.7 to about 2.7 weight per cent silicon, and less than about 8 weight per centmolybdenum as suggested in the above-mentioned US patent No. 6,l7l,657. In thecontext of Yankees, it should be noted that the term “coating” may also be used to referto liquid coating that is continuously sprayed onto the surface of the Yankee duringoperation which is fundamentally different from the hard coating that is applied as a partof the manufacturing process. When discussing application of a hard layer in order toincrease hardness and resistance to wear, a technical term often used by persons skilledin the art is “metallization” and this term and “to metallize” (except when used inreference to other documents that are cited herein and that use the term in a differentmeaning) will be used in this patent application and all patents that may be grantedbased on it to refer to the application of a hard and wear-resistant layer perrnanentlyjoined to the steel drying surface of the Yankee, regardless of the exact composition ofthat layer. Such a layer will be called “metallization layer” in the following. The term“coating” as used henceforth in this patent application will refer to the application of atemporary liquid coating during operation of a tissue paper making machine (exceptwhen used in reference to other documents that are cited herein and that use the tenn in a different meaning).

Steel used for making steel Yankees has a hardness which is markedly lower than thatof cast iron. A typical Value for the hardness of such steel may be on the order of about140 HB or, possibly, in the range of 120 - 170 HB.

Since steel has a hardness (on the order of 140 HB) that is substantially lower than thatof cast iron (220 - 260 HB), it has been a requirement that Yankees made of steel bemetallized. Different metallization layers for steel Yankees have been proposed. In apaper from 2007, Mr. Jörg Bauböck discussed a steel Yankee with a “metallic coating”with a surface hardness which was said to be double that of cast iron (“Application of aSteel Yankee in Tissue Machines”, TAPPI Yankee Dryer Safety Committee, J acksonville 10/23/07) although no details were given about the exact composition. In a2008 paper by Mr. Luca Mignani (“Advances with Steel Yankee Dryers”, TISSUEWORLD, Asia 2008), Mr. Mignani suggested that a steel Yankee dryer can be providedwith a “metal coating” (i.e. metallization layer) and that the “metal coating” may be forexample an alloy with a high content of Cr and Ni and have a hardness of 60 HRC.Although hardness measured according to HRC does not correspond directly to Brinellhardness, the value of 60 HRC can be said to correspond to about 600 HB. In the samepaper, Mr. Mignani also suggests that INFINIKOTE® can be used. Infinikote® is a trade mark owned by Valmet Corporation and refers to metallization of Yankees Withthermal spraying and Which, at least in one version thereof, is free from chromium. Thepaper by Mr. Mignani gives the hardness value in this case as “S0 to 60 HRC”, i.e. onthe order of about 500 - 600 HB.

As an alternative to metallization, it has been suggested that the shell of a steel Yankeebe hardened by laser and such a solution is disclosed in AT 519996 A2. According tothat document, it is possible to obtain a hardness value of up to 400 HB.

However, both currently known technologies for metallization and possible hardeningby laser represent a further step in the manufacturing process of a Yankee Which makes the manufacturing process more complicated.

With regard to metallized steel Yankees, the inventors of the present invention have alsonoted that streaks can occur in the paper that has been dried on such dryers.

The inventors have also seen that the metallization layer of a Yankee may crack and/ordelaminate Which makes it necessary to halt production and shut off the machine. When this occurs, production is seriously disturbed and the costs for this may be very high.

Therefore, it is an object of the present invention to provide a machine using a steelYankee that is properly protected against surface Wear and Which can yet bemanufactured in a simple Way. A further object of the invention is to prevent theoccurrence of streaks in the paper that is died on the machine. It is also an object toprovide a method of manufacturing tissue paper Which reduces Wear on the dyingsurface of the Yankee and Which reduces the risk of disturbances in the production.

BRIEF SUMMAY OF THE IN VENTION The invention relates to a machine for making tissue paper. The machine comprises aYankee having a shell Which has a circular cylindrical shape and a heatable outersurface (i.e. the drying surface) Which heatable outer surface is a steel surface. TheYankee is arranged to be rotatable about a longitudinal axis of rotation in a direction ofrotation. The machine further comprises an imprinting fabric that forms a continuousloop and Which is arranged to carry a fibrous Web to the Yankee. At least the Web-contacting side of the imprinting fabric has a texture such that a three-dimensionalpattem can be imprinted into the fibrous Web if the imprinting fabric is pressed into thefibrous Web. A press roll is arranged inside the loop of the imprinting fabric and forms a non-dewatering transfer nip against the Yankee. A creping doctor is arranged to act against the outer surface of the shell to crepe a dried fibrous Web from the outer surfaceof the shell. A coating device Which, in the direction of rotation of the Yankee, islocated after the creping doctor but before the transfer nip is arranged to be capable ofapplying a liquid coating onto the outer surface of the shell. The shell is a non- metallized steel shell.

Since the shell is a non-metallized steel shell, the outer surface of the shell is formed bysteel and the creping doctor Will thus act against a surface formed by steel instead of acting against a surface formed by a metallization layer.

Preferably, the outer surface of the shell is formed by a steel material having a Brinellhardness in the range of 120 HBW - 170 HBW, preferably in the range of 130 - 160HBW. In_this context, the HBW hardness Value for the outer surface of the shell of theYankee should be understood as the value as verified according to ISO 6506-1, HBW10/3000. While the indicated range of hardness values is a preferred range,embodiments are conceivable in Which the outer surface of the shell has a differentvalue for hardness, for example up to 180 HBW.

In preferred embodiments, the machine may optionally comprise a supply system for acoating fluid Which supply system is connected to the coating device such that it cansupply coating to the coating device. The supply system and the coating device may bedimensioned such that, When the machine is running With a machine speed of 1600m/minute, the coating device can deliver coating to the outer surface of the shell in aquantity in the range of 15 mg/mz - 120 mg/mzand preferably such that, at a machinespeed of 2000 rn/minute, the coating device can deliver coating to the outer surface ofthe shell in a quantity up to 120 mg/mz. In this context, the term “machine speed” is tobe understood as the peripheral speed of the outer surface (the drying surface) of theshell of the Yankee.

In embodiments of the invention, a cleaning doctor may be arranged to act against theouter surface of the shell at a location which, in the direction of rotation of the Yankee, is located after the creping doctor but before the coating device.

According to a first embodiment, the machine may additionally comprise at least onethrough-air drying cylinder. In this embodiment, the imprinting fabric Will be an airpermeable fabric Which is arranged to carry a fibrous Web over a part of thecircumference of the at least one through-air drying cylinder and to carry the fibrousWeb from the at least one through-air drying cylinder to the transfer nip formed between the press roll and the Yankee.

According to a second embodiment of the invention, the imprinting fabric is an airpermeable fabric and the machine also comprises an endless belt that forms a loop andhas an outer side/outer surface which is covered by polyurethane. The machine furthercomprises a felt forming a loop and a press roll is located inside the loop of the felt.Another press roll is located inside the loop of the endless belt and forms a dewateringnip with the press roll inside the loop of the felt. The endless belt is arranged to carry afibrous web that has been dewatered in the dewatering nip from the dewatering nip to anintermediate transfer point located between the dewatering nip and the non-dewateringtransfer nip formed against the Yankee. A suction pick-up roll is placed inside the loopof the imprinting fabric at the intermediate transfer point and is arranged to pick up thefibrous web from the endless belt and transfer it to the imprinting fabric. The imprintingfabric then is arranged to carry the fibrous Web from the intermediate transfer point to the transfer nip formed against the Yankee.

In a variation of the second embodiment, a nip roll may optionally be located inside theloop of the endless belt and form a transfer nip against the suction roll within the loop ofthe imprinting fabric such that the intermediate transfer point is a transfer nip.

In a third embodiment, the imprinting fabric may be an endless substantiallyimpermeable belt having a web-contacting surface defining a multitude of depressions.In this embodiment, a dewatering nip is formed between a press roll within the loop of the imprinting fabric and a counter roll located within the loop of a Water-absorbing felt.

The press roll that forms a transfer nip With the Yankee may advantageously be a rollwith a cover in a polymeric material and the thickness of the cover is in the range of 15mm - 35 mm, preferably 20 mm - 25 mm, and a hardness in the range of 20 - 40 P&J(Pusey & Jones hardness according to standard test method D531-00). The cover maybe a cover with grooves, but it can also be a cover with a plain outer surface without grooves.

However, it should be understood that the press roll in the transfer nip against theYankee may very well take other forms than a roll with such a cover. For example, it may conceivably be a shoe roll.

The creping doctor may have a blade which has a free length in contact With the outer surface of the shell which is in the range of 12 mm - 25 mm.

The invention also relates to a method for making tissue paper. The inventive method comprises forrning a fibrous web in a forming section and carrying the newly formed fibrous Web on one or several fabrics of Which at least one is an imprinting fabric thatforms a loop. At least the Web-contacting side of the imprinting fabric has a texture. Thefibrous Web is carried on the imprinting fabric to a Yankee Which rotates about alongitudinal axis of rotation in a direction of rotation and has a shell With a Circularcylindrical shape and an outer surface. The fibrous Web is transferred from theimprinting fabric to the Yankee in a non-dewatering transfer nip formed between theYankee and a press roll arranged inside the loop of the imprinting fabric such that thetextured Web-contacting side of the imprinting fabric imprints a three-dimensionalpattern into the fibrous Web in the transfer nip. The fibrous Web is then dried on theouter surface of the shell of the Yankee. A creping doctor is used to crepe the driedfibrous Web from the outer surface of the shell. A liquid coating is applied on the outersurface of the shell at a location Which, in the direction of rotation of the Yankee, liesafter the creping doctor but before the non-dewatering transfer nip. The shell is a non-metallized steel shell such that the outer surface of the shell is formed by non-metallizedsteel. Preferably, the non-metallized steel is untreated apart from the manufacturing mechanical processes such as Welding, turning, milling, grinding, polishing and the like.

The liquid coating is applied preferably by means of a coating device Which, in thedirection of rotation of the Yankee, is located after the creping device but before thetransfer nip. The method may then further comprise the step of causing a cleaningdoctor to act against the outer surface of the shell at a location Which, in the direction of rotation of the Yankee, is located after the creping doctor but before the coating device.

In embodiments of the inventive method, the method may comprise applying a linearload on the creping doctor Which is in the range of 4.0 kN/m - 10 kN/m. For example,the linear load may be in the range of 4.0 kN/m - 7.5 kN/m or in the range of 8.0 kN/m- 10 kN/m.

The liquid coating may preferably be applied onto the outer surface of the shell in aquantity of 15 mg/mz - 120 mg/mz, more preferably 15 mg/mz - 80 mg/mz and evenmore preferably in a quantity of 30 mg/mz - 75 mg/mz. HoWever, the coating may alsobe applied in quantities even higher than 120 mg/mz.

The coating that is applied may optionally comprise 50 - 65 % by Weight polyvinylalcohol (PVOH), an adhesive that constitutes 15 - 30 % by Weight of the coating, amodifier/release agent that constitutes 5 - 30 % by Weight of the coating and preferablyalso phosphate. Phosphate used for such coating may be, for example, mono- ammonium phosphate, Di-ammonium phosphate, trisodium phosphate or tetra phosphate. Instead of the above-mentioned phosphates (or in combination with one or several of them), phosphoric acid may be used in the coating.

In the transfer nip against the Yankee, a linear load may optionally be applied which isin the range of 40 kN/m - 100 kN/m, preferably in the range of 45 kN/m - 90 kN/m.

The inventive method may take the form that the imprinting fabric is an air permeablefabric that carries the fibrous web over a part of the circumference of at least onethrough-air drying cylinder and then carries the fibrous web from the at least onethrough-air drying cylinder to the transfer nip formed between the press roll and theYankee.

Alternatively, the method may take such a form that the imprinting fabric is an airperrneable fabric while the method also comprises carrying the web on a felt that formsa loop to a dewatering nip formed between a press roll inside the loop of the felt and acounter roll within the loop of an endless belt having an outer web-contacting sidewhich is covered by polyurethane. The fibrous web is then dewatered in the dewateringnip and transferred to the endless belt. The fibrous web is carried on the endless beltaway from the dewatering nip and the fibrous web is then picked from the endless beltand transferred to the imprinting fabric by a suction device arranged inside the loop ofthe imprinting fabric. This is followed by carrying the fibrous web to the transfer nipformed against the Yankee by the press roll which is arranged inside the loop of theimprinting fabric. Preferably, the imprinting fabric runs with a speed that is lower thanthe speed of the endless belt.

Alternatively, the method may be performed with an imprinting fabric which is anendless substantially impermeable belt having a web-contacting surface defining amultitude of depressions. The method then comprises the step of dewatering the fibrousweb in a dewatering nip which is formed between a press roll within the loop of theimprinting fabric and a counter roll located within the loop of a water-absorbing felt.The fibrous web is then carried on the imprinting fabric to the transfer nip and transferred to the outer surface of the shell of the Yankee.

BRIEF DESCRIPTION OF THE FIGURESFIG. 1 is a schematic cross-sectional representation of a Yankee.FIG. 2 is a schematic side view of the Yankee during operation.

FIG. 3 is a schematic side view of a creping doctor acting against a Yankee.

FIG. 4 is a schematic side view of an embodiment of the inventive tissue paper making machine.

FIG. 5 is a schematic side view of a second embodiment of the inventive tissue paper making machine.

FIG. 6 is a schematic side view of a third embodiment of the inventive tissue paper making machine.

Fig. 7 is a schematic cross-sectional view of a press roll used in the invention.

DETAILED DESCRIPTION OF THE INVENTION With reference to Fig. 1, the Yankee 2 which is used in the present invention has a shell3 with an outer surface 4 arranged between two end walls 29. The shell 3 is preferablywelded to the end walls 29, for example as disclosed in EP 2920360 Bl or in EP2126203 Bl. In Fig. 1, the welds are indicated by the reference numeral 31 and they arepreferably circumferential welds. The end walls 29 may optionally be provided withthennal insulation, for example as disclosed in EP 2475819 Bl or in WO 2016/026662Al. The Yankee 2 has journals 32 and, during operation, the Yankee 2 is intended torotate about an axis of rotation A which is the longitudinal axis of symmetry of theYankee 2. During operation, the Yankee 2 will be heated from the inside by steam. Thehot steam will transfer heat to the shell 3 such that the shell 3 is heated and can serve toevaporate water from a fibrous web when the fibrous web comes into contact with theouter surface 4 (i.e. drying surface 4) of the shell 3. Therefore, the Yankee is designedsuch that steam can be delivered into the Yankee 2. The inner surface of the shell 3 maybe provided with circular grooves in which condensate is collected as disclosed in EP2126203. In preferred embodiments, the Yankee may also be designed such thatcondensate can be removed from the interior of the Yankee 2 and the Yankee may thushave a condensate removal device. For example, the Yankee 2 may have a condensateremoval device as disclosed in US patent No. 5,090, 135 or in EP 2614182 Bl.

With reference to Fig. 2, the Yankee 2 is represented rotating about its axis of rotationA in the direction of arrow R, i.e. “clockwise” in Fig. 2. As can be understood from Fig.2, the shell 3 has a circular cylindrical shape. The Yankee 2 is so arranged in the tissuepaper making machine that it is rotatable about the axis of rotation A. The Yankee 2may optionally be provided with a Yankee drying hood 30, for example such a Yankeedrying hood as is disclosed in EP 2963176 Bl but other Yankee drying hoods may also be considered and the inventive machine may also operate without a Yankee dryinghood.

An imprinting fabric 5 that forms a continuous loop is arranged to carry a fibrous webW to the Yankee 2. At least the web-contacting side 6 of the imprinting fabric 5 has atexture such that a three-dimensional pattern can be imprinted into the fibrous web 5when the imprinting fabric 5 is pressed into the fibrous web W. A press roll 7 isarranged inside the loop of the imprinting fabric 5 and forms a non-dewatering transfernip TN against the Yankee 2. It should be understood that, during operation, the pressroll 7 Will act with a certain linear load against the shell 3 of the Yankee 2 and the linearload may suitably be in the range of 40 kN/m - 100 kN/m, preferably in the range of 45kN/m - 90 kN/m. This means that the texture of the imprinting fabric 5 will be pressedinto the fibrous web W while it is still relatively wet. During operation, the texturedweb-contacting side 6 of the imprinting fabric 5 will thus imprint a three-dimensionalpattern into the fibrous web W in the transfer nip TN. The fibrous web W is then driedon the outer surface 4 of the shell 3 of the Yankee 2. In Fig. 2, it can be seen how acreping doctor 8 is arranged to act against the outer surface 4 of the shell 3 to crepe theready-dried fibrous web W from the outer surface 4 of the shell 3 as is known as such inthe art to which the invention pertains. As seen in the direction of rotation R of theYankee 2, a coating device 10 is located after the creping doctor 8 but before thetransfer nip TN. The coating device 10 is arranged to apply a liquid coating onto theouter surface 4 of the shell 3. The coating is dissolved in water and may be suppliedfrom a system/arrangement 11 for supplying an aqueous solution of a liquid coating tothe coating device 10. The coating itself (i.e. apart from the water) suitably contains 50- 65 % by weight polyvinyl alcohol (PVOH), adhesive at an amount of 15 - 30 % byweight and a modifier/release agent which may constitute 5 - 30 % by weight. In addition, the coating may contain phosphate.

For processes in which an imprinting fabric is used to deliver the fibrous web W to theYankee, the inventors have found that more coating should be applied than in otherprocesses for manufacturing tissue paper. In a more conventional process in which a feltis used to convey the fibrous web to the Yankee, coating is typically applied in anamount of 4 - 10 mg/mz (not including the water in which the coating is dissolved).However, the inventors have found that, in processes in which an imprinting fabric 5delivers the fibrous web W to the outer surface 4 of the shell 3, a larger amount ofcoating should be applied. If the layer of coating is too thin, there is a considerable riskthat the imprinting fabric 5 will damage the web W instead of giving it the desired three-dimensional pattern that increases the bulk of the fibrous web. The inventors have found that, for such processes, liquid coating should be applied in a quantity of at least15 mg/mz and suitably even higher quantities. The precise amount that is requireddepends on the process but there are cases where quantities up to 120 mg/mz may beconsidered. In many realistic cases, the amount of coating may be within the range of 15 mg/mz - 80 mg/mz, 30 mg/mz - 75 mg/mz, or 30 mg/mz - 55 mg/mz.

The inventors have found that, when coating is applied in such quantities, the coatingitself can act as sufficient protection for the outer surface 4 of the shell 3 of the Yankee2. This makes it possible to use a steel shell 3 with an outer surface 4 that is entirelynon-metallized and the coating is then applied directly onto the steel drying surface (i.e.onto the outer surface 4 of the shell 3). Thereby, the complicated process of metalizingthe shell 3 can be entirely avoided. Preferably, the non-metallized steel is not treatedwith any mechanical processes apart from the manufacturing process such as welding, tuming, milling, grinding polishing and the like.

Moreover, the inventors have established that the hard, outer layer of a metallizedYankee entails a disadvantage. While the metallization protects against wear, there is arisk that cracks will occur in the hard layer and the hard layer of metallization may evendelaminate. This can damage the doctor blade which is intended to be even and verysharp. When a crack catches the doctor blade, the doctor blade can be deformed, and theinventors have found that this is a source of streaks in the paper. Therefore, theinventors have concluded that elimination of the metallization layer is actually desirable from a process point of view.

The inventors have also seen that streaks in the paper is a phenoinenon that very oftenprecedes such a major collapse of the metallization layer that the entire machine must beshut off such that the Yankee can be repaired or replaced. Without wishing to be boundby theory, it is believed that streaks in the paper is a warning sign that a major collapseof the metallization layer is imminent.

While it is currently unknown to the inventors if a laser hardened surface may entail arisk that the doctor blade is damaged, they have concluded that such a hardening isactually not necessary at all if coating is applied in a sufficient quantity and thus eliminating the laser treatment results in a less complicated manufacturing process.

With reference to Fig. 2, it can be seen that a cleaning doctor 12 is arranged to actagainst the outer surface 4 of the shell 2 at a location which, in the direction of rotationR of the Yankee 2, is located after the creping doctor 8 but before the coating device 10.

The cleaning doctor 12 removes remaining fibres and coating. While the cleaning 11 doctor 12 is advantageous, it is not an absolute requirement for practicing the invention and it is thus optional.

With further reference to Fig. 3, it can be seen that the creping doctor 8 has a blade 9that acts against the outer surface 4 of the Yankee shell 3. The blade 9 is held in a bladeholder 33. From the blade holder 33, the blade 9 has a free length L in contact with theouter surface 4 of the shell 3 which is in the range of 12 mm - 25 mm. The expression“free length” should here be understood as the distance from the blade holder 33 to thesurface 4 of the Yankee shell 3. When the doctor blade 9 acts against a surface 4 ontowhich coating has been supplied in such large quantities (i.e. 15 mg/mz and higher), thelinear load of the creping doctor 8 must be higher than what would otherwise have beenthe case. For processes in which the fibrous web W is not transferred to the Yankee byan imprinting fabric, in particular processes in which the fibrous web W is carried to theYankee by a felt, the linear load may be on the order of 1.5 kN/m - 3.5 kN/m. However,in processes using an imprinting fabric and in which larger quantities of coating is used,the linear load may be from 4 kN/m - 10 kN/m. Such higher linear loads can be used toprevent the coating film from building up to a thickness that would be detrimental to theprocess or even make continued operation impossible. Since the use of an imprintingfabric makes it desirable to use more liquid coating than what is the case with processesin which a felt carries the fibrous web to the Yankee, higher linear loads than otherwiseare used to control the layer of liquid coating, i.e. to prevent that the layer of liquidcoating builds up and becomes too thick. With such higher linear loads, the free lengthL should preferably be smaller than what would be the case in a more conventionalprocess. With a shorter free length L, the blade 9 can take the higher linear loads better.In such processes where the linear load is lower, the free length of the blade may be in the range of 30 mm - 40 mm.

The creping doctor 8 may optionally be arranged such that it can be moved toward oraway from the outer surface 4 of the shell 3. This may be the case when, for example,the blade 9 is to be exchanged. For example, the doctor can be pivoted away from theouter surface 4 (or pivoted toward the outer surface 4).

A possible embodiment of the invention will now be explained with reference to Fig. 4.In this embodiment, the inventive machine 1 includes a through-air drying cylinder 13.

In the embodiment of Fig. 4, only one through-air drying cylinder 13 is used. However,it should be understood that embodiments of the invention with two or even mote such through-air drying cylinders are conceivable. In the embodiment of Fig. 4, a fibrous web W is formed in a forming section 25 with a headbox 26 and the fibrous web is 12 formed between two fabrics 5, 34 of which the fabric 34 is used as a fonning fabric. Thefabric 5 is also used as a forming fabric but also serves as the imprinting fabric. Thefibrous web W is formed when stock is ejected into the forrning gap 37 between thefabrics 5, 34 and passed over the forming roll 36 as is known in the art. In thisembodiment, the imprinting fabric 5 is a through-air drying fabric which carries thefibrous web W over a part of the circumference of the through-air drying cylinder 13.The through-air drying fabric (i.e. the imprinting fabric 5) then carries the fibrous webW to the transfer nip TN between the Yankee 2 and the press roll 7. In this embodiment,the imprinting fabric 5 is thus an air permeable fabric. An example of such a fabricwhich may be used in the embodiment of Fig. 4 is disclosed in US patent No. 7,878,223. Another example of an imprinting fabric that may be used in theembodiment of Fig. 4 is disclosed in US patent No. 9,062,414. When the fibrous web Whas been transferred to the Yankee 2, it will be creped off from the outer surface 4 of theYankee shell as explained with reference to Fig. 2 and coating will be applied by thecoating device 10. During creping, the creping doctor 8 will act against the non-metallized outer surface of the shell 3 and the coating device will supply liquid coatingwhich, in addition to its other functions, also serves to protect the non-metallized steeldrying surface of the shell 3 of the Yankee 2. As can be seen in Fig. 4, the liquid coatingis applied to the outer surface 4 of the shell 3 at a location which, in the direction ofrotation R of the Yankee 2, lies after the creping doctor 8 but before the non-dewateringtransfer nip TN. The outer surface 4 of the shell 3 is formed by a steel material that maytypically have a Brinell hardness (HBW) in the range of 120 - 170, preferably in therange of 130 - 160. A typical value for the hardness may be about 140 HBW or 145HBW.

The steel (normally rolled steel) used in the shell may be a grade known as EN P355NH (a steel grade following the standard EN10028-3). This steel grade is suitable forpressure vessels such as Yankees. Other steel grades that could be used include gradesaccording to ASME SA 516 standard and an example of a steel grade that can be used isASME SA 516 grade 70. Steel grades according to ASME SA 36 may also beconsidered as well as steel grades according to the standard Q345R (Chinese Guobiaostandard).

When the fibrous web W has been creped off from the outer surface 4 of the Yankeeshell 3, it can be sent to a reel-up (not shown in Fig. 4). In Fig. 4, the fabrics 5, 34 aresupported by rolls 35 and the fabrics 5, 34 are running in the direction indicated byarrows P. 'Ihe overall machine direction is indicated by the arrow MD. It should be understood that the precise arrangement of various components in Fig. 4 is only an 13 example and variations of the configuration are conceivable. For example, theimprinting fabric 5 is not necessarily used as a forming fabric in the forming section 25but could be arranged to receive the fibrous web W from a separate forming fabric.Although only a creping doctor 8 is shown in Fig. 4, it should be understood that theembodiment of Fig, 4 could very well include a cleaning doctor 12 as indicated in Fig.2. While a Yankee drying hood 30 is indicated in Fig. 4, it should be understood that,while this may be advantageous, it is an optional feature. In the embodiment of Fig. 4,the coating device 10 may supply liquid coating containing PVOH to the outer surface 4of the Yankee shell in a quantity which may suitably be in the range of 30 mg/mz - 120mg/mz, preferably 30 mg/mz - 75 mg/mz and even more preferred 30 mg/mz - 50mg/mz. In some cases, the liquid coating may conceivably be supplied in quantitiesdown to 20 mg/mz. The linear load for the creping doctor may suitably be in the rangeof 8 kN/m - 10 kN/m but other values are also conceivable. As explained with referenceto Fig. 2, the linear load applied in the transfer nip TN against the Yankee 2 may be inthe range of 40 kN/m - 100 kN/m, preferably in the range of 45 kN/m - 90 kN/m.

Yet another embodiment will now be explained with reference to Fig. 5. In theembodiment of Fig. 5, a fibrous web W is fonned in the forming section 25 which has ahead box 26 for injecting stock between the fabrics 34, 15 of which the fabric 15 is awater-receiving felt. The reference numeral 36 indicates a forming roll and the fabricsare supported in their path by rolls 35. The newly formed fibrous web W is carried bythe felt 15 to a dewatering nip 18. The dewatering nip is formed between a press roll 16located within the loop of the felt 15 and a press roll 17 which is located within the loopof an endless belt 14. The reference numeral 38 indicates an optional suction turningroll that can contribute to dewatering. The endless belt 14 has an outer side/surface 40which is the web-contacting surface of the endless belt 14. The outer side 40 of theendless belt 14 is covered by polyurethane and is much smoother than the web-contacting surface of the felt 15 such that the fibrous web will be easily transferred tothe endless belt 14. The endless belt 14 canies the fibrous web W from the dewateringnip 18 to an intermediate transfer point ITP located between the dewatering nip 18 andthe non-dewatering transfer nip TN formed against the Yankee 2. When the fibrous webreaches the intermediate transfer point ITP, it is transferred to the imprinting fabric 5 bymeans of a suction device 19 located within the loop of the imprinting fabric 5 which isan air permeable fabric having a texture such that a three-dimensional pattern can beimprinted into the still wet fibrous web W. The suction device 19 may be a suction boxor a suction pick-up roll or the like. The suction device 19 picks up the fibrous web W from the endless belt 14 and transfers it to the imprinting fabric 5. The imprinting fabric 14 then canies the fibrous web W from the intermediate transfer point ITP to the transfernip TN formed against the Yankee 2 and the fibrous web W is transferred to the Yankee2, dried on the hot drying surface 4 of the Yankee and creped away from the Yankee 2by the creping doctor 8. During creping, the creping doctor 8 will act against the non-metallized outer surface of the shell 3 and the coating device will supply liquid coatingWhich, in addition to its other functions, also serves to protect the non-metallized steelshell 3 of the Yankee 2. The outer surface 4 (the drying surface) of the shell 3 is formedby a steel material that may typically have a Brinell hardness in the range of 120 HBW- 170 HBW, preferably in the range of 130 - 160. A typical value for the hardness maybe about 140 HBW or 145 HBW.

After creping, the fibrous web W will be sent to a reel-up schematically indicated by thereference numeral 39. The reel-up 39 may be, for example, such as reel-up as disclosedin US patent No. 5,901,918 but any reel-up suitable for tissue paper may be considered.The coating device 10 supplies liquid coating containing PVOH to the outer surface 4 ofthe Yankee shell in a quantity which may suitably be in the range of 30 mg/mz - 120mg/mz, preferably 30 mg/mz - 75 mg/mz and even more preferred 30 mg/mz - 50mg/mz. In some cases, the liquid coating may conceivably be supplied in quantitiesdown to 20 mg/mz. As can be seen in Fig. 5, the liquid coating is applied to the outersurface 4 of the shell 3 at a location which, in the direction of rotation R of the Yankee2, lies after the creping doctor 8 but before the non-dewatering transfer nip TN. Thelinear load for the creping doctor may suitably be in the range of 8 kN/m - 10 kN/m butother values are also conceivable. Although no cleaning doctor is shown in Fig. 5, itshould be understood that a cleaning doctor could optionally be present. Although noYankee drying hood is shown in Fig. 5, it should likewise be understood that themachine 1 may optionally have such a Yankee drying hood. As explained withreference to Fig. 2, the linear load applied in the transfer nip TN against the Yankee 2may be in the range of 40 kN/m - 100 kN/m, preferably in the range of 45 kN/m - 90kN/m.

If the suction transfer device 19 is a suction roll, a nip roll 20 may optionally be placedwithin the loop of the endless belt 14 and form a transfer nip with the suction roll. Theintennediate transfer point ITP will then be a transfer nip.

Preferably, but not necessarily, the imprinting fabric 5 runs with a linear speed that islower than the linear speed of the endless belt 14. In the embodiment of Fig. 5, theendless belt may be running with a linear speed that is 5 % - 25 % higher than the linear speed of the imprinting fabric 5. In this way, a rush transfer is achieved that improves the caliper of the fibrous web W. For further understanding of the embodiment of Fig.5, reference is made to US patent No. 8,87l,060 which may serve as an additional source of information for how the embodiment of Fig. 5 can be implemented.

Yet another embodiment will now be explained with reference to Fig. 6. A fibrous webW is formed in a forming section 25 where a head box 26 is arranged to inject stock in agap formed between a forming fabric 34 and a water-absorbing (water-receiving) felt15. The felt 15 and the forrning fabric run in their loops supported by lead rolls 35. Thefelt carries the newly formed fibrous web W to a dewatering nip formed between a pressroll 22 within the loop of the water-receiving felt 15 and a press roll 21 (or counter roll21). The press roll 21 is located within the loop of the imprinting fabric 5. The press roll22 may optionally be a shoe roll. In the embodiment of Fig. 6, the imprinting fabric 5 isan endless substantially imperrneable belt having a web-contacting surface 6 defining amultitude of depressions. Thereby, a three-dimensional pattern can be imprinted into thefibrous web W, both in the dewatering nip 28 and in the transfer nip TN formed by thepress roll 7 and the Yankee 2. The imprinting fabric 5 in the embodiment of Fig. 6 maycomprise a back layer (which does not contact the web) and a web-contacting layer thatforms the web-contacting side 6 of the imprinting fabric 5. The web-contacting layer(side) has a multitude of depressions that may be uniformly distributed or distributed ina non-uniform way. The web-contacting side 6 may have flat or arched portions situatedbetween the depressions. A coating of a polymer may be applied to the side of the fabricthat does not come into contact with the fibrous web W. An example of a possibleimprinting fabric 5 for the embodiment of Fig. 6 is disclosed in US patent No.6,547,924 but the imprinting fabric 5 may also take other forms. However, theembodiment of Fig. 6 is intended for a substantially impermeable imprinting fabric,unlike the imprinting fabrics for the embodiments of Fig. 4 and Fig. 5. After havingpassed through the dewatering nip 28, the fibrous web is carried by the imprinting fabric5 to the transfer nip TN and transferred to the Yankee 2 and dried on the Yankee 2while the Yankee rotates in the direction of arrow R. The fibrous web W is then crepedoff from the outer surface of the Yankee shell 3 by the creping doctor 8. During creping,the creping doctor 8 will act against the non-metallized outer surface of the shell 3 andthe coating device will supply liquid coating which, in addition to its other functions,also serves to protect the non-metallized drying surface 4 of the steel shell 3 of theYankee 2. As can be seen in Fig. 6, the liquid coating is applied to the outer surface 4 ofthe shell 3 at a location which, in the direction of rotation R of the Yankee 2, lies afterthe creping doctor 8 but before the non-dewatering transfer nip TN. The outer surface 4 of the shell 3 is formed by a steel material that may typically have a Brinell hardness in 16 the range of 120 HBW - 170 HBW, preferably in the range of 130 HBW - 160 HBW.A typical value for the hardness may be about 140 HBW or 145 HBW.

In the embodirnent of Fig. 6, the linear load used for the creping doctor 8 may suitablybe in the range of 4 kN/m - 7.5 kN/m and liquid coating may preferably be supplied in aquantity of 15 mg/m2 - 30 mg/m2 although other linear loads and other quantities of liquid coating may also be considered.

The Yankee drying hood 30 that is shown in Fig. 6 may be, for example, a Yankeedrying hood as disclosed in EP 2963176 Bl but other Yankee drying hoods may also be considered and the inventive machine may also operate Without a Yankee drying hood.

While a cleaning doctor 12 is shown in Fig. 6, it should be understood that this cleaningdoctor 12 is optional, even if it is an advantageous feature. When a cleaning doctor 12 isused, it Will be caused to act against the outer surface 4 of the shell 3 at a locationWhich, in the direction of rotation R of the Yankee 2, is located after the creping doctor8 but before the coating device. This applies to all embodiments.

In all embodiments of the invention, the press roll 7 that forms a transfer nip TN Withthe Yankee 2 may be a roll With a cover 24 having a thickness in the range of 15 mm -35 mm, preferably 20 mm - 25 mm, and a hardness in the range of 20 - 40 P&J, see Fig. 7. The cover is made of or comprises a polymeric material.

The cover 24 may have a plain outer surface Without grooves, alternatively it could also be provided With groves.

The press roll 7 that is used in the transfer nip against the Yankee may conceivably takeother forms than a roll With a cover 24. For example, it may conceivably be a shoe rollWith a design as disclosed in US patent No. 7,527,708; US patent No. 9,885,153 or EP2085513 Bl. As another example, a suction roll could also be considered in this position.

In all embodiments of the invention, in particular in all embodiments of the inventivemethod, the linear load in the transfer nip TN, i.e. may be in the range of 40 kN/m - 100kN/m, preferably in the range of 45 kN/m - 90 kN/m. Other linear loads may also beconsidered but practical experience has demonstrated to the inventors that the linearloads indicated are best suited if a three-dimensional pattem is to be imprinted into thefibrous Web W.

It should be understood that, in all embodiments of the invention, the machine 1 Wouldnormally have a supply system ll for a coating fluíd which supply system 11 is 17 connected to the coating device 10 such that it can supply coating to the coating device.The supply system ll and the coating device 10 must be so dimensioned that they candeliver the required quantity of liquid coating. Preferably, the supply system 11 and thecoating device 10 should be dimensioned such that, When the machine is running With aspeed of 1600 m/minute, the coating device 10 can deliver liquid coating to the outersurface 4 of the shell 3 in a quantity in the range of 15 mg/mz - 120 mg/mz. Even morepreferred, they should be so dimensioned that, even at a machine speed of 2000m/minute, the coating device 10 can deliver coating to the outer surface of the shell 3 ina quantity of up to 120 mg/mz.

In all embodiments, the liquid coating that is applied contains a substantial amount ofpolyvinyl alcohol (PVOH) and suitable compositions may comprise 50 - 65 % byWeight polyvinyl alcohol (PVOH), an adhesive that constitutes 15 - 30 % by Weight ofthe coating, a modifier/release agent that constitutes 5 - 30 % by Weight of the coatingand preferably also phosphate.

In all embodiments of the invention, the tissue paper making machine may be running ata speed Which is in the range of 1200 m/min - 2000 m/min. HoWever, higher speedsmay also be considered and machine speeds in the range of 2000 m/min - 2300 m/minmay also be used or possibly even speeds up to 2400 rn/min. In all embodiments of theinvention, the Yankee may have a diameter in the range of, for example, 3 m - 7 m. Forexample, the diameter may be 3.5 m; 3.66 m; 4.88 m or 5.5 m. The width of the Yankee2 may be, for example, in the range of 1.5 m - 7 m. For example, the width could be 3m or 5 m. HoWever, the Yankee could also have other dimensions than the ones given above.

The end Walls of the Yankee may be provided With thermal insulation to reduce heat losses. For example, the end Walls may be provided With thermal insulation as disclosedin EP 2475819 Bl.

In the context of this patent application and any patent that may be granted based on thisapplication, the term “tissue paper” should be understood as referring to paper With abasis Weight which is equal to or greater than 12 g/mz and equal to or less than 45 g/mz, in particular equal to or greater than 12 g/mz and equal to or less than 30 g/mz.

Thanks to the inventive solution of using liquid coating as a Way of protecting theYankee shell 3, it is possible to avoid the complicated metallization process. Moreover,since the Yankee does not have a layer of metallization, the invention significantly reduces the risk of deformation to the doctor blade due to faults in the metallization 18 layer. Thereby, the risk of streaks in the tissue paper that is manufactured can be reduced.

Elimination of the metallization layer also reduces the risk that the machine must be shut down because of damages to the drying surface of the Yankee.

While the invention has been discussed above in terms of a machine and a method, itshould be understood that these categories merely reflect different aspects of one andthe same invention. The method may thus include any step that Would be the natural result of using the machine in its various embodiments and the machine may include means for performing any functional step of the method.

Claims (9)

1. A machine (1) for making tissue paper, the machine (1) comprising a Yankee (2)having a shell (3) Which has a circular cylindrical shape and an outer surface (4),the Yankee (2) being arranged to be rotatable about an axis of rotation (A) in adirection of rotation (R); an imprinting fabric (5) that forms a continuous loopand is arranged to carry a fibrous Web (W) to the Yankee (2), at least the Web-contacting side (6) of the imprinting fabric (5) having a texture such that a three-dimensional pattern can be imprinted into the fibrous Web (5) When theimprinting fabric (5) is pressed into the fibrous web (W); a press roll (7)arranged inside the loop of the imprinting fabric (5) and forming a non-dewatering transfer nip (TN) against the Yankee (2); a creping doctor (8)arranged to act against the outer surface (4) of the shell (3) to crepe a driedfibrous Web (W) from the outer surface (4) of the shell (3); and a coating device(10) Which, in the direction of rotation (R) of the Yankee (2), is located after thecreping doctor (8) but before the transfer nip, the coating device (10) beingarranged to be capable of applying a liquid coating onto the outer surface (4) ofthe shell (3), characterized in that the shell (3) is a non-metallized steel shell. A machine (1) according to claim 1, Wherein a cleaning doctor (12) is arrangedto act against the outer surface (4) of the shell (3) at a location Which, in thedirection of rotation (R) of the Yankee (2), is located after the creping doctor (8)but before the coating device (10). A machine (1) according to claim 1 or 2, Wherein the machine (1) comprises atleast one through-air drying cylinder (13) and Wherein the imprinting fabric (5)is an air permeable fabric Which is arranged to carry a fibrous Web over a part ofthe circumference of the at least one through-air drying cylinder (13) and tocarry the fibrous Web from the at least one through-air drying cylinder (13) tothe transfer nip formed between the press roll (7) and the Yankee (2). A machine (1) according to claim 1 or 2, Wherein the imprinting fabric (5) is anair permeable fabric; Wherein the machine (1) comprises an endless belt (14) thatforms a loop and has an outer surface (40) Which is covered by a layer of polyurethane; a felt (15) forming a loop; a press roll (16) located inside the loop of the felt (15) ; a press roll (17) located inside the loop of the endless belt (14)and forming a dewatering nip (18) With the press roll (16) inside the loop of thefelt (15), the endless belt ( 14) being arranged to carry a fibrous Web (W) that hasbeen dewatered in the dewatering nip (18) from the dewatering nip (18) to anintermediate transfer point (ITP) located between the dewatering nip (18) andthe non-dewatering transfer nip (TN) formed against the Yankee (2), Wherein asuction device (19) is placed inside the loop of the imprinting fabric (5) at theintermediate transfer point (ITP) and arranged to pick up the fibrous Web (W)from the endless belt (14) and transfer it to the imprinting fabric (5), andWherein the imprinting fabric (5) is arranged to carry the fibrous Web (W) fromthe intermediate transfer point (ITP) to the transfer nip (TN) formed against theYankee (2). . A machine (1) according to claim 4, Wherein the suction device (19) is a suction roll and a nip roll (20) is located inside the loop of the endless belt (14) andforms a transfer nip against the suction roll Within the loop of the imprintingfabric (5) such that the intermediate transfer point (ITP) is a transfer nip. . A machine (1) according to claim 1 or 2, Wherein the imprinting fabric (5) is an endless substantially impermeable belt having a Web-contacting surface (6)defining a multitude of depressions and Wherein a dewatering nip (28) is formedbetween a press roll (21) Within the loop of the imprinting fabric (5) and acounter roll (22) located Within the loop of a Water-absorbing felt (15). . A machine (1) according to claim 1, Wherein the press roll (7) that forms a transfer nip (TN) With the Yankee (2) is a roll With a cover (24) having athickness in the range of 15 mm - 35 mm, preferably 20 mm - 25 mm, and ahardness in the range of 20 - 40 P&J. . A machine (1) according to claim 7, Wherein the cover has a plain outer surface Without grooves. 9. 10. 11. 1

2. 21 A machine (1) according to claim 1, Wherein the outer surface (4) of the shell (3)is formed by a steel material having a Brinell hardness in the range of 120 HBW- 170 HBW, preferably in the range of 130 HBW - 160 HBW. A machine (1) according to claim 1, Wherein the creping doctor (8) has a blade(9) Which has a free length in contact With the outer surface (4) of the shell (3)Which is in the range of 12 mm - 25 mm. A machine (1) according to claim 1, Wherein the machine (1) further comprises asupply system (11) for a coating fluid Which supply system (1 1) is connected tothe coating device (10) such that it can supply coating to the coating device andWherein the supply system (11) and the coating device (10) are dimensionedsuch that, When the machine is running With a speed of 1600 m/minute, thecoating device (10) can deliver coating to the outer surface (4) of the shell (3) ina quantity in the range of 15 mg/mz - 120 mg/mzand preferably such that, at amachine speed of 2000 m/minute, the coating device (10) can deliver coating tothe outer surface of the shell (3) in a quantity up to 120 mg/mz. A method for making tissue paper, the method comprising; forming a fibrousWeb (W) in a forming section (25); carrying the newly formed fibrous Web (W)on one or several fabrics of Which at least one is an imprinting fabric (5) thatforms a loop and at least the Web-contacting side (6) of the imprinting fabric (5)having a texture; carrying the fibrous Web (W) on the imprinting fabric (5) to aYankee (2) Which rotates about an axis of rotation (A) in a direction of rotation(R) and has a shell (3) with a circular cylindrical shape and an outer surface (4);transferring the fibrous Web (W) from the imprinting fabric (5) to the Yankee (2)in a non-dewatering transfer nip (TN) formed between the Yankee (2) and apress roll (7) arranged inside the loop of the imprinting fabric (5) such that thetextured Web-contacting side of the imprinting fabric (5) imprints a three-dimensional pattern into the fibrous Web (W) in the transfer nip (TN); drying thefibrous Web (W) on the outer surface (4) of the shell (3) of the Yankee (2); usinga creping doctor (8) to crepe the dried fibrous Web (W) from the outer surface(4) of the shell (3); applying a liquid coating on the outer surface (4) of the shell(3) at a location Which, in the direction of rotation (R) of the Yankee (2), lies 1

3. 1

4. 1

5. 1

6. 1

7. 1

8. 22 after the creping doctor (8) but before the non-dewatering transfer nip (TN),characterized in that the shell (3) is a non-metallized steel shell such that the outer surface (4) of the shell (3) is formed by non-metallized steel. A method according to claim 12, Wherein the liquid coating is applied by meansof a coating device (10) Which, in the direction of rotation (R) of the Yankee (2),is located after the creping doctor (8) but before the transfer nip (TN), andWherein the method further comprises causing a cleaning doctor (12) to actagainst the outer surface (4) of the shell (3) at a location Which, in the directionof rotation (R) of the Yankee (2), is located after the creping doctor (8) but before the coating device. A method according to claim 12, Wherein the method further comprises applyinga linear load on the creping doctor (8) Which is in the range of 4.0 kN/m - 10kN/m. A method according to claim 14, Wherein the linear load is in the range of 4.0kN/m - 7.5 kN/m. A method according to claim 14, Wherein the linear load is in the range of 8.0kN/m - 10 kN/m. A method according to claim 12, Wherein the coating is applied onto the outersurface (4) of the shell (3) in a quantity of 15 mg/mz - 120 mg/mz, preferably 15mg/mz - 80 mg/mz and even more preferred in a quantity of 30 mg/mz - 75 mg/mz. A method according to claim 12 or claim 17, Wherein the liquid coating isapplied in an aqueous solution and the liquid coating comprises 50 - 65 % byWeight polyvinyl alcohol (PVOH), an adhesive that constitutes 15 - 30 % by 1

9. 20. 21. 22. 23 weight of the coating, a modifier/release agent that constitutes 5 - 30 % byweight of the coating and preferably also phosphate. A method according to claim 12, wherein the method further comprises applyinga linear load in the transfer nip which is in the range of 40 kN/m - 100 kN/m,preferably in the range of 45 kN/m - 90 kN/m. A method according to claim 12, wherein the imprinting fabric (5) is an airpermeable fabric and wherein the method further comprises carrying the fibrousweb (W) on the imprinting fabric (5) over a part of the circumference of at leastone through-air drying cylinder (13) and carrying the fibrous web (W) from theat least one through-air drying cylinder (13) to the transfer nip formed betweenthe press roll and the Yankee (2). A method according to claim 12, wherein the imprinting fabric (5) is an airpermeable fabric and wherein the method comprises carrying the fibrous web(W) on a felt that fonns a loop to a dewatering nip formed between a press rollinside the loop of the felt and a counter roll within the loop of an endless belt(14) having an outer Web-contacting side which is covered by polyurethane;dewatering the fibrous web (W) in the dewatering nip and transferring thefibrous web (W) to the endless belt (14); carrying the fibrous web (W) on theendless belt (14) away from the dewatering nip; picking the fibrous web (W)from the endless belt (14) and transferring it to the imprinting fabric (5) by asuction device arranged inside the loop of the imprinting fabric and carrying thefibrous web (W) to the transfer nip (TN) formed against the Yankee (2) by thepress roll (7) which is arranged inside the loop of the imprinting fabric (5). A method according to claim 21, wherein the imprinting fabric (5) runs with aspeed that is lower than the speed of the endless belt. 24 23. A method according to claim 12, Wherein the imprinting fabric (5) is an endlesssubstantially impermeable belt having a Web-contacting surface defining amultitude of depressions and Wherein the method comprises dewatering thefibrous Web (W) in a dewatering nip (28) Which is formed between a press roll(21) Within the loop of the imprinting fabric (5) and a counter roll (22) locatedWithin the loop of a Water-absorbing felt and subsequently carrying the fibrousWeb (W) on the imprinting fabric (5) to the transfer nip and transferring thefibrous Web to the outer surface (4) of the shell (3) of the Yankee (2).