Apparatus for and Process of Material Web Formation

(19) &

(11) EP 1 709 243 B1

(12) EUROPEAN PATENT SPECIFICATION

(45) Date of publication and mention (51) Int Cl.: of the grant of the patent: D21F 11/00 (2006.01) D21F 11/14 (2006.01) 13.02.2008 Bulletin 2008/07 D21F 9/00 (2006.01)

(21) Application number: 05707801.6 (86) International application number: PCT/EP2005/050203 (22) Date of filing: 19.01.2005 (87) International publication number: WO 2005/075737 (18.08.2005 Gazette 2005/33)

(54) APPARATUS FOR AND PROCESS OF MATERIAL WEB FORMATION ON A STRUCTURED FABRIC IN A PAPER MACHINE VORRICHTUNG UND VERFAHREN ZUR MATERIALBAHNBILDUNG AUF STRUKTURIERTER PAPIERMASCHINENBESPANNUNG APPAREIL ET PROCEDE DE FORMATION D’UNE BANDE DE MATIERE SUR UN TISSU STRUCTURE DANS UNE MACHINE A PAPIER

(84) Designated Contracting States: • SCHERB, Thomas Thoröe AT BE BG CH CY CZ DE DK EE ES FI FR GB GR CEP 05628-010 Sao Paulo (BR) HU IE IS IT LI LT LU MC NL PL PT RO SE SI SK TR (74) Representative: Kunze, Klaus et al (30) Priority: 30.01.2004 US 768550 Voith Paper Holding GmbH & Co. KG Abteilung zjp (43) Date of publication of application: Sankt Pöltener Strasse 43 11.10.2006 Bulletin 2006/41 89522 Heidenheim (DE)

(73) Proprietor: Voith Patent GmbH (56) References cited: 89522 Heidenheim (DE) WO-A-03/000002 GB-A- 2 324 314 US-A- 5 277 761 US-A- 5 503 715 (72) Inventors: US-A1- 2003 102 098 • HERMAN, Jeffrey Bala Cynwyld, PA 19004 (US)

Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention). EP 1 709 243 B1

Printed by Jouve, 75001 PARIS (FR) 1 EP 1 709 243 B1 2

Description collecting fibers from the fiber slurry in at least one valley of the structured fabric. The method according to the in- 1. Field of the invention. vention is characterized in that moisture that leaves said fiber slurry travels through said forming fabric and not [0001] The present invention relates to a method of 5 through said structured fabric and the figer slurry be- forming a structured fiber web on a paper machine, and, comes a fiber web after the moisture is removed through more particularly, to a method and apparatus of forming the forming fabric. a structured fiber web on a structured fabric in a paper [0008] The invention further provides a fiber web form- machine. ing apparatus, comprising: a headbox ; a forming roll ; a 10 structured fabric; a forming fabric, a portion of one of said 2. Description of the related art. structured fabric and said forming fabric in contact with a portion of said forming roll, a side of said structured [0002] In a wet molding process, a structured fabric in fabric and a side of said forming fabric becoming proxi- a Crescent Former configuration impresses a three di- mate to each other thereby forming a nip, said headbox mensional surface on a web while the fibrous web is still 15 discharging a fibrous slurry directed at said nip, said fi- wet. Such an invention is disclosed in International Pub- brous slurry losing moisture through said forming fabric lication No. WO 03/062528 A1. A suction box is disclosed and not through said structured fabric. for the purpose of shaping the fibrous web while wet to [0009] An advantage of the present invention is that generate the three dimensional structure by removing air the low density pillow areas have a relatively higher fiber through the structural fabric. It is a physical displacement 20 basis weight than that provided with other methods. of portions of the fibrous web that leads to the three di- [0010] Another advantage is that the ratio of the un- mensional surface. Similar to the aforementioned meth- compressed fiber mass to the compressed fiber mass is od, a through air drying (TAD) technique is disclosed in much higher, with the same overall basis weight than U.S. Patent No. 4,191,609. The TAD technique discloses was achievable in the prior art. how an already formed web is transferred and molded 25 [0011] Yet another advantage is that the fibrous web into an impression fabric. The transformation takes place formed by the method of the present invention allows for on a web having a sheet solids level greater that 15%. a superior transfer of the web to a Yankee drying surface. This results in a low density pillow area in the fibrous [0012] Still yet another advantage of the present in- web. These pillow areas are of a low basis weight since vention is that hood associated with the Yankee dryer the already formed web is expanded to fill the valleys 30 can utilize a higher temperature for drying the pillow por- thereof. The impression of the fibrous web into a pattern, tions of the fibrous web, without burning the pillow por- on an impression fabric, is carried out by passing a vac- tions. uum through the impression fabric to mold the fibrous [0013] An additional advantage of the present inven- web. tion is that the structured fabric can have deeper valleys [0003] What is needed in the art is a method to produce 35 or pockets than a prior art fabric, since the pillow portions a fibrous web with a high basis weight pillow area of low of the fibrous web are thicker and have a higher basis density to thereby increase the absorption and bulk char- weight, eliminating the pin hole problems associated with acteristics of the finished fibrous web. prior art methods, which results in a thicker more absorb- [0004] From prior art documents WO0300002 and ent web. US20030102098 the forming of a tissue web between a 40 structured and a smooth fabric is known to improve bulk- BRIEF DESCRIPTION OF THE DRAWINGS iness of the tissue sheet. [0005] According to prior art documents US5277761, [0014] The above-mentioned and other features and GB2324314 and US5503715 a tissue web is formed on advantages of this invention, and the manner of attaining top a smooth forming fabric and lateron transferred to a 45 them, will become more apparent and the inv ention will structured fabric to provide a tissue web with peaks and be better understood by reference to the following de- valleys. scription of embodiments of the invention taken in conjunction with the accompanying drawings, wherein: SUMMARY OF THE INVENTION 50 Fig. 1 is a cross-sectional schematic diagram illus- [0006] The present invention provides a method of pro- trating the formation of a structured web using an ducing a structured fibrous web having a high basis embodiment of a method of the present invention; weight pillow area of low density on a paper machine Fig. 2 is a cross-sectional view of a portion of a struc- using a structured fabric. tured web of a prior art method; [0007] The invention comprises, in one form thereof, 55 Fig. 3 is across -sectional view of a portion of the a method of forming a structured web including the steps structured web of an embodiment of the pres ent of providing a fiber slurry through a headbox to a nip invention as made on the machine of Fig. 1; formed by a structured fabric and a forming fabric and Fig. 4 illustrates the web portion of Fig. 2 having sub-

2 3 EP 1 709 243 B1 4

sequently gone through a press drying operation; thereon. Structured fabric 28 travels in direction W, and Fig. 5 illustrates a portion of the fiber web of the as moisture M is driven from fibrous slurry 24, structured present invention of Fig. 3 having subsequently gone fibrous web 38 takes form. Moisture M that leaves slurry through a press drying operation; 24 travels through forming fabric 26 and is collected in Fig. 6 illustrates a resulting fiber web of the forming 5 save -all 36. Fibers in fibrous slurry 24 collect predomi- section of the present invention; nately in valleys 28b as web 38 takes form. Fig. 7 illustrates the resulting fiber web of the forming [0017] Structured fabric 28 includes warp and weft section of a prior art method; yarns interwoven on a textile loom. Structured fabric 28 Fig. 8 illustrates the moisture removal of the fiber may be woven flat or in an endless form. The final mesh web of the present invention; 10 count of structured fabric 28 lies between 95 x 120 and Fig. 9 illustrates the moisture removal of the fiber 26 x 20. For the manufacture of toilet tissue, the preferred web of a prior art structured web; mesh count is 51 x 36 or higher and more preferably 58 Fig. 10 illustrates the pressing points on a fiber web x 44 or higher. For the manufacturer of paper towels, the of the present invention; preferred mesh count is 42 x 31 or lower, and more pref- Fig. 11 illustrates pressing points of prior art struc- 15 erably 36 x 30 or lower. Structured fabric 28 may have a tured web; repeated pattern of 4 shed and above repeats, preferably Fig. 12 illustrates a schematical cross -sectional view 5 shed or greater repeats. The warp yarns of structured of an embodiment of a papermaking machine of the fabric 28 have diameters of between 0.12 mm and 0.70 present invention; mm, and weft yarns have diameters of between 0.15 mm Fig. 13 illustrates a schematical cross -sectional view 20 and 0.60 mm. The pocket depth, which is the offset be- of another embodiment of a papermaking machine tween peak 28a and valley 28b is between approximately of the present invention; 0.07 mm and 0.60 mm. Yarns utilized in structured fabric Fig. 14 illustrates a schematical cross -sectional view 28 may be of any cross -sectional shape, for example, of another embodiment of a papermaking machine round, oval or flat. The yarns of structured fabric 28 can of the present invention; 25 be made of thermaplastic or thermaset polymeric mate- Fig. 15 illustrates a schematical cross -sectional view rials of any color. The surface of structured fabric 28 can of another embodiment of a papermaking machine be treated to provide a desired surface energy, thermal of the present invention; resistance, abrasion resistance and/or hydrolysis resist- Fig. 16 illustrates a schematical cross -sectional view ance. A printed design, such as a screen printed design, of another embodiment of a papermaking machine 30 of polymeric material can be applied to structured fabric of the present invention; 28 to en hance its ability to impart an aesthetic pattern Fig. 17 illustrates a schematical cross -sectional view into web 38 or to enhance the quality of web 38. Such a of another embodiment of a papermaking machine design may be in the form of an elastomeric cast structure of the present invention; and similar to the Spectra® membrane described in another Fig. 18 illustrates a schematical cross -sectional view 35 patent application. Structured fabric 28 has a top surface of another embodiment of a papermaking machine plane contact area at peak 28a of 10% or higher, prefer- of the present invention. ably 20% or higher, and more preferably 30% depending upon the particular product being made. The contact area [0015] Corresponding reference characters indicate on structured web 28 at peak 28a can be increased by corresponding parts throughout the several views. The 40 abrading the top surface of structured fabric 28 or an exemplifications set out herein illustrate one preferred elastomeric cast structure can be formed thereon having embodiment of the invention, in one form, and such ex- a flat top surface. The top surface may also be hot cal- emplifications are not to be construed as limiting the endered to increase the flatness. scope of the invention in any manner. [0018] Forming roll 34 is preferably solid. Moisture 45 travels through forming fabric 26 but not through struc- DETAILED DESCRIPTION OF THE INVENTION tured fabric 28. This advantageously forms structured fibrous web 38 into a more bulky or absorbent web than [0016] Referring now to the drawings, and more par- the prior art. ticularly to Fig. 1, there is a fibrous web machine 20 in- [0019] Prior art methods of moisture removal, remove cluding a headbox 22 that discharges a fibrous slurry 24 50 moisture through a structured fabric by way of negative between a forming fabric 26 and a structured fabric 28. pressure. It results in a cross -sectional view as seen in Rollers 30 and 32 direct fabric 26 in such a manner that Fig. 2. Prior art structured web 40 has a pocket depth D tension is applied thereto, against slurry 24 and struc- which corresponds to the dimensional difference be- tured fabric 28. Structured fabric 28 is supported by form- tween a valley and a peak. The valley occurring at the ing roll 34 which rotates with a surface speed that match- 55 point where measurement C occurs and the peak occur- es the speed of structured fabric 28 and forming fabric ring at the point where measurement A is taken. A top 26. Str uctured fabric 28 has peaks 28a and valleys 28b, surface thickness A is formed in the prior art method. which give a corresponding structure to web 38 formed Sidewall dimension B and pillow thickness C of the prior

3 5 EP 1 709 243 B1 6 art result from moisture drawn through a structured fabric. C. Subsequent pressing at the Yankee dryer 52, as Dimension B is less than dimension A and dimension C shown in Fig. 11, further reduces the basis weight in area is less than dimension B in the prior art structure. C. In contrast, water is drawn through dewatering fabric [0020] In contrast, structured web 38, as illustrated in 82 in the present invention, as shown in Fig. 8, preserving Figs. 3 and 5, have for discussion purposes, a pocket 5 pillow are as C’. Pillow areas C’ of Fig. 10, is an unpressed depth D that is similar to the prior ar t. However, sidewall zone, which is supported on structured fabric 28, while thickness B’ and pillow thickness C’ exceed the compa- pressed against Yankee 52. Pressed zone A’ is the area rable dimensions of web 40. This advantageously results through whichmost of the pressure applied is transferred. from the forming of structural web 38 on structured fabric Pillow area C’ has a higher basis weight than that of the 28 at low consistency and the removal of moisture is an 10 illustrated prior art structures. opposite direction from the prior art. This results in a thick- [0026] The increased mass ratio of the present inven- er pillow dimension C’. Even after fiber web 38 goes tion, particularly the higher basis weight in the pillow area through a drying press operation, as illustrated in Fig. 5, s carries more water than the compressed areas, result dimension C’ is substantially greater than Aρ’. Advanta- ing in at least twopositive aspects of the presentinvention geously, the fiber web resulting from the present inven- 15 over the prior art, as illustrated in Figs. 10 and 11. First, tion has a higher basis weight in the pillow areas as com- it allows for a good transfer of the web to the Yankee pared to prior art. Also, the fiber to fiber bonds are not surface 52, since the web has a relatively lower basis broken as they can be in impression operations , which weight in the portion that comes in contact with the Yan- expand the web into the valleys. kee surface 52, at a lower overall sheet solid content than [0021] According to prior art an already formed web is 20 had been previously attainable, because of the lower vacuum transferred into a structured fabric. The sheet mass of fibers that comes in contact with the Yankee must then expand to fill the contour of the structured fab- dryer 52. The lower basis weight means that less water ric. In doing so, fibers must move apart. Thus the basis is carried to the contact points with the Yankee dryer 52. weight is lower in these pillow areas and therefore the The compressed areas are dryer than the pillow areas, thickn ess is less than the sheet at point A. 25 thereby allowing an overall transfer of the web to another [0022] Now, referring to Fig’s 6 to 11 the process will surface, such as a Yankee dryer 52, with a lower overall be explained by simplified shematic drawings. web solids content. Secondly, the construct allows for [0023] As shown in Fig. 6, fibrous slurry 24 is formed the use of higher temperatures in the Yankee hood 54 into a web 38 with a structure inherent in the shape of without scorching or burning of the pillow areas, which structured fabric 28. Forming fabric 26 is porous and al- 30 occurs in the prior art pillow areas. The Yankee hood 54 lows moisture to escape during forming. Further, water temperatures are often greater than 350° C and prefer- is removed as shown in Fig. 8, through dewatering fabric ably greater than 450° C and even more preferably great- 82. The removal of moisture through fabric 82 does not er than 550° C. As a result the present invention can cause a compression of pillow areas C’ in the forming operate at lower average pre -Yankee press solids than web, since pillow areas C’ reside in the structure of struc- 35 the prior art, making more full use of the capacity of the tured fabric 28. Yankee Hood drying system. The present invention can [0024] The prior art web 40 shown in Fig. 7, is formed allows the solids content of web 38 prior to the Yankee with a conventional forming fabric as between two con- dryer to run at less than 40%, less than 35% and even ventional forming fabrics in a twin wire former and is char- as low as 25%. acterized by a flat uniform surface. It is this fiber web that 40 [0027] Due to the formation of the eb 38 with the struc- is given a three -dimensional structure by a wet shaping tured fabric 28 the pockets of the fabric 28 are fully filled stage, which results in the fiber web that is shown in Fig. with fibres. 2. A conventional tissue machine that employs a conven- [0028] Therefore, at the Yankee surface 52 the web tional press fabric will ha ve a contact area approaching 38 has a much higher contact area, up to approx. 100 100%. Normal contact area of the structured fiber, as in 45 % , as compared to the prior art because the web 38 on this present invention, or as on a TAD machine, is typi- the side contacting the Yankee surface 52 is almost flat. cally much lower than that of a conventional machine, it At the same time the pillow areas C’ of the web 38 main- is in the range of 15 to 35% depending on the particular tain unpressed, because they are protected by the valeys pattern of the product being made. of the structured fabric 28 (Fig. 10). Good results in drying [0025] In Figs. 9 and 11 a prior art web structure is50 efficiency were obtained only pressing 25 % of the web. shown where moisture is drawn through a structured fab- [0029] As can be seen in Fig. 11 the contact area of ric 33 causing the web, as shown in Fig. 7, to be shaped the prior art web 40 to the Yankee surface 52 is much and causing pillow area C to have a low basis weight as lower as compared to the one of the web 38 manufac- the fibers in the web are drawn into the structure. The tured according to the invention. shaping can be done by performing pressure or under- 55 [0030] The lower contact area of the prior art web 40 pressure to the web 40 forcing the web 40 to follow the results from the shaping of the web 40 that now follows structure of the structured fabric 33. This additionally the structure of the structured fabric 33. causes fiber tearing as they are moved into pillow area [0031] Due to the less co ntact area of the prior art web

4 7 EP 1 709 243 B1 8

40 to the Yankee surface 52 the drying efficiency is less. a typical multilayer design. In either case, the base fabric [0032] Now, additionally referring to Fig. 12, there is is needled with a fine batt fiber having a weight of less shown an embodiment of the process where a structured than or equal to 700 gsm, preferably less than or equal fiber web 38 is formed. Structured fabric 28 carries a th to 150 gsm and more preferably less than or equal to 135 ree dimensional structured web 38 to a n advanced de- 5 gsm. The batt fiber encapsulates the base structure giv- watering system 50 , past suction box 67 and then to a ing it sufficient stability. The needling process can be Yankee roll 52 where the web is transferred to Yankee such that straight through channels are created. The roll 52 and hood section 54 for additional drying and cre- sheet contacting surface is heated to improve its surface ping before winding up on a reel (not shown). smoothness. The cross-sectional area of the machine [0033] A shoe press 56 is placed adjacent to structured 10 direction yarns is larger than the cross - sectional area fabric 28, holding it in a position proximate Yankee roll of the cross -direction yarns. The machine direction yarn 52. Structured web 38 comes into contact with Yankee is a multifilament yarn that may include thousands of fib- roll 52 and transfers to a surface thereof, for further drying ers. The base fabric is connected to a batt layer by a and subsequent creping. needling process that results in straight through drainage [0034] A vacuum box 58 is placed adjacent to struc- 15 channels. tured fabric 28 to achieve a solids level of 15-25% on a [0037] In another embodiment of dewatering fabric 82 nominal 20 gsm web running at -0.2 to -0.8 bar vacuum there is included a fabric layer, at least two batt layers, with a preferred operating level of -0.4 to -0.6 bar. Web an anti-rewetting layer and an adhesive. The base fabric 38, which is carried by structured fabric 28, contacts de- is substantially similar to the previousdescription. At least watering fabric 82 and proceeds toward vacuum roll 60. 20 one of the batt layers include a low melt bi-compound Vacuum roll 60 operates at a vacuum level of -0.2 to -0.8 fiber to supplement fiber to fiber bonding upon heating. bar with a preferred operating level of at least -0.4 bar. On one side of the base fabric, there is attached an anti Hot air hood 62 is optionally fit over vacuum roll 60 to -rewetting layer, which may b e attached to the base fab- improve dewatering. If for example, a commercial Yan- ric by an adhesive, a melting process or needling wherein kee drying cylinder with 44 mm steel thickness and a25 the material contained in the anti- rewet layer is connect- conventional hood with an air blowing speed of 145 m/s ed to the base fabric layer and a batt layer. The anti- is used production speeds of 1400 m/min or more for rewetting layer is made of an elastomeric material there- towel paper and 1700 m/min or more for toilet paper are by forming elastomeric membrane , which has openings used. therethrough. [0035] Optionally a steam box can be installed instead 30 [0038] The batt layers are needled to thereby hold de- of the hood 62 supplying steam to the web 38. Preferably watering fabric 82 together. This advantageously leaves the steam box has a sectionalized design to influence the batt layers with many needled holes therethrough. the moisture re-dryness cross profile of the web 38. The The anti - rewetting layer is porous having water channels length of the vacuum zone inside the vacuum roll 60 can or straight through pores therethrough. be from 200 mm to 2,500 mm, with a preferable length 35 [0039] In yet an other embodiment of dewatering fabric of 300 mm to 1,200 mm and an even more preferable 82, there is a construct substantially similar to that pre- length of between 400 mm to 800 mm. The solids level viously discussed with an addition of a hydrophobic layer of web 38 leaving suction roll 60 is 25% to 55% depending to at least one side of de-watering fabric 82. The hydro- on instal led options. A vacuum box 67 and hot air supply phobic layer does not absorb water, but it does direct 65 can be used to increase web 38 solids after vacuum 40 water through pores therein. roll 60 and prior to Yankee roll 52. Wire turning roll 69 [0040] In yet another embodiment of dewatering fabric can also be a suction roll with a hot air supply hood. Roll 82, the base fabric has attached thereto a lattice grid 56 includes a shoe press with a sh oe width of 80 mm or made of a polymer, such as polyure thane, that is put on higher, preferably 120 mm or higher, with a maximum top of the base fabric. The grid may be put on to the base peak pressure of less than 2.5 MPa. To create an even 45 fabric by utilizing various known procedures, such as, for longer nip to facilitate the transfer of web 38 to Yankee example, an extrusion technique or a screen -printing 52, web 38 carried on structured fabric 28 can be brought technique. The lattice grid may be put on the base fabric into contact with the surface of Yankee roll 52 prior to the wit h an angular orientation relative to the machine direc- press nip associated with shoe press 56. Further, the tion yarns and the cross direction yarns. Although this contact can be maintained after structured fabric 28 trav- 50 orientation is such that no part of the lattice is aligned els beyond press 56. with the machine direction yarns, other orientations can [0036] Dewatering fabric 82 may have a permeable also be utilized. The lattice can have a uniform grid pat- woven base fabric connected to a batt layer. The base tern, which can be discontinuous in part. Further, the ma- fabric includes machine direction yarns and cross -direc- terial between the interconnections of the lattice structure tional yarns. The machine direction yarn is a 3 ply multi- 55 may take a circuitous path rather than being substantially filament twisted yarn. The cross - direction yarn is a straight. The lattice grid is made of a synthetic, such as monofilament yarn. The machine direction yarn can also a polymer or specifically a polyurethane, which attaches be a monofilament yarn and the construction can be of itself to the base fabric by its natural adhesion properties.

5 9 EP 1 709 243 B1 10

[0041] In yet another embodiment of dewatering fabric belt 66 capable of apply ing pressure to the non -sheet 82 there is included a permeable base fabric having ma- contacting side of structured fabric 28 that carries web chine direction yarns and cross-direction yarns, that are 38 around suction roll 60. Fabric 66 of belt press 64 is adhered to a grid. The grid is made of a composite ma- also known as an extended nip press belt or a link fabric, terial the may be the same as that discussed relative to 5 which can run at 60 KN/m fabric tension with a pressing a previous embodiment of dewatering fabric 82. The grid length that is longer than the suction zone of roll 60. includes machine direction yarns with a composite ma- [0047] Preferred embodiments of the fabric 66 and the terial formed therearound. The grid is a composite struc- required operation concillation are also described in ture formed of composite material and machine direction PCT/EP2004/053688 and PCT/EP2005/050198. yarns. The machine direction yarns may be pre -coated 10 [0048] The above mentioned references are also fully with a composite before being placed in rows that are applicable for dewatering fabrics 82 and press fabrics 66 substantially parallel in a mold t hat is used to reheat the described in the further embodiments. composite material causing it to re-flow into a pattern. [0049] While pressure is applied to structured fabric Additional composite material may be put into the mold 28, the high fiber density pillow areas in web 38 are pro- as well. The grid structure, also known as a composite 15 tected from that pressure as they are contained within layer, is then connected to the base fabric by one of many the body of structured fabric 28, as they are in the Yankee techniques including laminating the grid to the permeable nip. fabric, melting the composite coated yarn as it is held in [0050] Belt 66 is a specially designed Extended Nip position against the permeable fabric or by re-melting the Press Belt 66, made of, for example reinforced poly- grid onto the base fabric. Additionally, an adhesive may 20 urethane and/or a spiral link fabric. Belt 66 is permeable be utilized to attach th e grid to permeable fabric. thereby allowing air to flow therethrough to enhance the [0042] The batt fiber may include two layers, an upper moisture removing capability of belt press 64. Moisture and a lower layer. The batt fiber is needled into the base is drawn from web 38 through dewatering fabric 82 and fabric and the composite layer, thereby forming a dewa- into vacuum roll 60. tering fabric 82 having at least one outer batt layer sur- 25 [0051] Belt 66 provides a low level of pressing in the face. Batt material is porous by its nature, additionally rang e of 50-300 KPa and preferably greater than 100 the needling process not only connects the layers togeth- KPa. This allows a suction roll with a 1.2 meter diameter er, it also creates numerous small porous cavities ex- to have a fabric tension of greater than 30 KN/m and tending into or completely through the structure of dewa- preferably greater than 60 KN/m. The pressing length of tering fabric 82. 30 permeable belt 66 against fabric 28, wh ich is indirectly [0043] Dewatering fabric 82 has an air permeability of supported by vacuum roll 60, is at least as long as a from 5 to 100 cubic feet/ minute preferably 19 cubic feet/ suction zone in roll 60. Although the contact portion of minute or higher and more preferably 35 cubic feet/ belt 66 can be shorter than the suction zone. minute or higher. Mean pore diameters in dewatering fab- [0052] Permeable belt 66 has a pattern of holes there- ric 82 are from 5 to 75 microns, preferably 25 microns or 35 through, which may, for example, be drilled, laser cut, higher and more preferably 35 microns or higher. The etched formed or woven therein. Permeable belt 66 may hydrophobic layers can be made from a synthetic poly- be monoplanar without grooves. In one embodiment, the meric material, a wool or a polyamide, for example, nylon surface of belt 66 has grooves and is placed in contact 6. The anti -rewet layer and the composite layer may be with fabric 28 along a portion of the travel of permeable made of a thin elastomeric permeable membrane made 40 belt 66 in belt press 64. Each groove connects with a set from a synthetic polymeric material or a polyamide that of the holes to allow the passage and distribution of air is laminated to the base fabric. in belt 66. Air is distributed along the grooves, which con- [0044] The batt fiber layers are made from fibers rang- stitutes an open area adjacent to contact areas, where ing from 0.5 d -tex to 22 d-tex and may contain a low melt the surface of belt 66 applies pressure against web 38. bi-compound fiber to supplement fiber to fib er bonding 45 Air enters permeable belt 66 through the holes and then in each of the layers upon heating. The bonding may migrates along the grooves, passing through fabric 28, result from the use of a low temperature meltable fiber, web 38 and fabric 82. The diameter of the holes may be particles and/or resin. The dewatering fabric can be less larger than the width of the grooves. The grooves may than 2.0 millimeters, or less than 1.50 millimeters, or less have a cross-section contour that is generally rectangu- than 1.25 milli meters or less than 1.0 millimeter thick. 50 lar, triangular, trapezoidal, semi-circular or semi-ellipti- [0045] Preferred embodiments of the dewatering fab- cal. The combination of permeable belt 66, associated ric 82 are also described in the PCT/EP2004/053688 and with vacuum roll 60, is a combination that has been PCT/EP2005/050198. shown to increase sheet solids by at least 15%. [0046] Now, additionally referring to Fig. 13, there is [0053] An example of another structure of belt 66 is shown yet another embodiment of the present invention, 55 that of a thin spiral link fabric, which can be a reinforcing which is substantially similar to the invention illustrated structure within belt 66 or the spiral link fabric will itself in Fig. 12, except that instead of hot air hood 62, there serve as belt 66. Within fabric 28 there is a three dimen- is a belt press 64. Belt press 64 includes a permeable sional structure th at is reflected in web 38. Web 38 has

6 11 EP 1 709 243 B1 12 thicker pillow areas, which are protected during pressing web 38 and fabric 28 into a vent roll. The air dispersion as they are within the body of structured fabric 28. As fabric may prevent web 38 from following one of the four such the pressing imparted by belt press assembly 64 cap rolls. The air dispersion fabric is very open, having upon web 38 does not negatively impact web quality, a permeability that equals or exceeds that of fabric 28. while it increases the dewatering rate of vacuum roll 60. 5 The drying rate of the HPTAD depends on the solids con- [0054] Now, additionally referring to Fig. 14, which is tent of web 3 8 as it enters the HPTAD. The preferred substantially similar to the embodiment shown in Fig. 13 drying rate is at least 500 kg/hr/m 2, which is a rate of at with the addition of hot air hood 68 placed inside of belt least twice that of conventional TAD machines. press 64 to enhance the dewatering capability of belt [0057] Advantages of the HPTAD process are in the press 64 in conjunction with vacuum roll 60. 10 areas of improved sheet dewatering without a significant [0055] Now, additionally referring to Fig. 15, there is loss in sheet quality, compactness in size and energy shown yet another embodiment of the present invention, efficency. Additionally, it enables higher pre- Yankee sol- which is substantially similar to the embodiment shown ids, which increase the speed potential of the invention. in Fig. 13, but including a boost dryer 70, which encoun- Further, the compact size of the HPTAD allows for easy ters structured fabric 28 . Web 38 is subjected to a hot 15 retrofit to an existing machine. The compact size of the surface of boost driver 70, structure web 38 rides around HPTAD and the fact that it is a closed system means that boost driver 70 with another woven fabric 72 riding on it cam be easily insulated and optimized as a unit to in- top of structured fabric 28. On top of woven fabric 72 is crease energy efficiency. a thermally conductive fabric 74, which is in contact with [0058] Now, additionally referring to Fig. 17, there is both woven fabric 72 and a cooling jacket 76 that applies 20 shown another embodiment of the present invention. cooling and pressure to all fabrics and web 38. Here This is significantly similar to Fig. 13 and 16 except for again, the higher fiber density pillow areas in web 38 are the addition of a two-pass HPTAD 80. In this case, two protected from the pressure as they are contained within vented rolls are used to double the dwell time of struc- the body of structured fabric 28. As such, the pressing tured web 38 relative to the design shown in Fig. 16. An process does not negatively impact web quality. The dry- 25 optional coarse mesh fabric may used as in the previous ing rate of boost dryer 70 is above 400 kg/hrm 2 and pref- embodiment. Hot pressurized air passes through web 38 erably above 500 kg/hrm 2. The concept of boost dry er carried on fabric 28 and onto the two vent rolls. It has 70 is to provide sufficient pressure to hold web 38 against been shown that depending on the configuration and size the hot surface of the dryer thus preventing blistering. of the HPTAD, that more than one HPTAD can be placed Steam that is formed at the knuckle points fabric 28 pass- 30 in series, which can eliminate the need for roll 60. es through fabric 28 andis condensedon fabric 72. Fabric [0059] Now, additionally referring to Fig. 18, a conven- 72 is cooled by fa bric 74 that is in contact with the cooling tional Twin Wire Former 90 may be used to replace the jacket, which reduces its temperature to well below that Crescent Former shown in previous examples. The form- of the steam. Thus the steam is condensed to avoid a ing roll can be either a solid or open roll. If an open roll pressure build up to thereby avoid blistering of web 38. 35 is used, care must be taken to prevent significant dewa- The condensed water is captured in woven fa bric 72, tering through the structured fabric to avoid losing basis which is dewatered by dewatering device 75. It has been weight in the pillow areas. The outer forming fabric 93 shown that depending on the size of boost dryer 70, the can be either a standard forming fabric or one such as need for vacuum roll 60 can be eliminated. Further, de- that disclosed in U.S. Patent No. 6,237,644. The inner pending upon the size of boost dryer 70, web 38 may be 40 forming fabric 91 must be a structured fabric 91 that is creped on the surface of boost dryer 70, thereby elimi- much coarser than the outer forming fabric. A vacuum nating the need for Yankee dryer 52. box 92 may be needed to ensure that the web stays with [0056] Now, additionally referring to Fig. 16, there is structured wire 91 and does not go with outer w ire 90. shown yet another embodiment of the present invention Web 38 is transferred to structured fabric 28 using a vac- substantially similar to the invention disclosed in Fig. 13 45 uum device. The transfer can be a stationary vacuum but with an addition of an air press 78, which is a four roll shoe or a vacuum assisted rotating pick-up roll 94. The cluster press that is used with high temperature air and second structured fabric 28 is at least the same coarse- is referred to as an HPTAD for additional web drying prior ness and preferably courser than first structured fabric to the transfer of web 38 to Yankee 52. Four roll cluster 91. The process from this point is the same as one of the press 78 includes a main roll and a vented roll and two 50 previously discussed processes. The registration of the cap rolls. The purpose of this cluster press is to provide web from the first structured fabric to the second struc- a sealed chamber that is capable of being pressurized. tured fabric is not perfect, as such some pillows will lose The pressure chamber contains high temperature air, for some basis weight during the expansion process, there- example, 150°C or higher and is at a significantly higher by losing some of the benefit of the present invention. pressure than conventional TAD technology, for exam- 55 However, this process option allows for running a differ- ple, greater than 1.5psi resulting in a much higher drying ential speed transfer, which has been shown to improve rate than a conventional TAD. The high pressure hot air some sheet properties. Any of the arrangements for re- passes through an optional air dispersion fabric, through moving water discussed above as may be used with the

7 13 EP 1 709 243 B1 14

Twin Wire Former arrangement and a conventional TAD. characterized in [0060] The fiber distribution of web 38 in this invention that moisture (M) that leaves said fiber slurry (24) is opposite that of the prior art, which is a result of re- travels through said forming fabric (26) and not moving moisture through the forming fabric and not through said structured fabric (28) and said fiber slur- through the structured fabric. The low density pillow ar- 5 ry (24) becomes a fiber web (38) after said moisture eas are of relatively higher basis weight than the sur- is removed through said forming fabric (26). rounding compressed zones, which is opposite of conventional TAD paper. This allows a high percentage of 2. The method of claim 1, wherein said forming fabric the fibers to remain uncompressed during the process. (26) has a zonally different fabric permeability. The sheet absorbency capacity as measured by the bas- 10 ket method, for a nominal 20 gsm web is equal to or 3. The method of claim 1, wherein said structured fabric greater than 12 grams water per gram of fiber and often (28) includes a plurality of peaks (28a) each of said exceeds 15 grams of water per gram fiber. The sheet peaks (28a) associated with at least one of said plu- bulk is equal to or greater than 10 cm 3/gm and preferably rality of valleys (28b). greater than 13 cm 3/gm. The sheet bulk of toilet tissue 15 is expected to be equal to or greater than 13 cm3/gm 4. The method of claim 3, wherein said fiber slurry (24) before calendering. substantially covers a portion of a surface of said [0061] With the basket method of measuring absorb- structured fabric (28) including at least one of said ency, five (5) grams of paper are placed into a basket. plurality of valleys (28b) and at least one adjacent The basket containing the paper is then weighted and 20 peak (28a). introduced into a small vessel of water at 20°C for 60 seconds. After 60 seconds of soak time, the basket is 5. The method of claim 4, wherein said fiber slurry(24) removed from the water and allowed to drain f or 60 sec- becomes the structured web (38) by way of said col- onds and then weighted again. The weight difference is lecting step. then divided by the paper weight to yield the grams of 25 water held per gram of fibers being absorbed and held 6. The method of claim 5, wherein the structured web in the paper. (38) has a pillow thickness (C’) associated with the [0062] Web 38 is formed from fibrous slurry 24 that structured web (38) formed in said valleys (28b), the headbox 22 discharges between forming fabric 26 and structured web (38) having a top surface thickness structured fabric 28. Roll 34 rotates and supports fabrics 30 associated with the structured web (38) formed on 26 and 28 as web 38 forms. Moisture M flows through said peaks (28a), said pillow thickness (C’) being fabric 26 and is captured in save all 36. It is the removal one of equal to and greater than said top surface of moisture in this manner that serves to allow pill ow thickness. areas of web 38 to retain agreater basis weight andthere- fore thickness than if the moisture were to be removed 35 7. The method of claim 5, wherein the structured web through structured fabric 28. Sufficient moisture is re- (38) has a pillow basis weight associated with the moved from web 38 to allow fabric 26 to be removed from structured web (38) formed in said valleys (28b), the web 38 to allow web 38 to pr oceed to a drying stage. structured web (38) having a top surface basis Web 38 retains the pattern of structured fabric 28 and weight associated with the structured web (38) any zonal permeability effects from fabric 26 that may be 40 formed on said peaks (28a), said pillow basis weight present. being one of equal to and greater than said top sur- [0063] While this invention has been described as hav- face basis weight. ing a preferred design, the present invention can be further modified within the scope of this disclosure. This 8. The method of claim 5, further comprising the steps application is therefore intended to cover any variations, 45 of: removing said forming fabric (26) from the struc- uses, or adaptations of the invention which fall within the tured web (38); contacting the structured web(38) limits of the appended claims. with a dewatering fabric (82); and applying pressure to the structured web (38) through said structured fabric (28). Claims 50 9. The method of claim 5, further comprising the step 1. A method of forming a structured web (38) with a of applying a negative air pressure against a portion paper machine, comprising the steps of : providing of a surface of said dewatering fabric (82) thereby a fiber slurry (24) through a headbox (22) to a nip removing moisture from the structured web (38) formed by a structured fabric (28) and a forming fab- 55 through said dewatering fabric (82). ric(26); and collecting fibers fromsaid fiber slurry (24) predominately in a plurality of valleys (28b) of said 10. The method of claim 5, further comprising the steps structured fabric (28), of : transferring the structured web (38) to a Yankee

8 15 EP 1 709 243 B1 16

dryer (52) at a transfer point; and retaining the struc- 18. The apparatus of claim 17, further comprising a vac- tured web (38) with said structured fabric (28) until uum device applying a negative air pressure against reaching said transfer point. a portion of a surface of said dewatering fabric (82) thereby removing moisture from said fiber web (38) 11. The method of claim10, wherein the structured web 5 through said dewatering fabric (82). (38) remains on said structured fabric (28) until said transfer point thereby ensuring that pillow areas of 19. The apparatus of claim 18, wherein said vacuum de- the structured web (38) formed in said valleys (28b) vice is a vacuum roll (60). have a higher basis weight than the rest of the structured web (38) and said pillow areas stay impressed. 10 20. The apparatus of claim 12, further comprising an extended nip press belt (64) in partial contact with an 12. A fiber web forming apparatus, comprising: a head- other side of said structured fabric (28). box (22); a forming roll (34); a structured fabric (28); a forming fabric (26), a portion of one of said struc- 21. The apparatus of claim 20, further comprising an air- tured fabric (28) and said forming fabric (26) in con- 15 flow device (68) additionally passing air through said tact with a portion of said forming roll (34), a side of extended nip press belt (64). said structured fabric (28) and a side of said forming fabric(26) becoming proximate to each other thereby 22. The apparatus of claim 12, further comprising at least forming a nip, said headbox (22) discharging a fi- one of a Yankee roll (52), a suction roll (60), a hot brous slurry (24) directed at said nip, said fibrous 20 air hood (54), a boost dryer, an air press, an HPTAD slurry (24) losing moisture through said forming fab- and a two pass HPTAD, said fibrous web (38) con- ric (26) and not through said structured fabric and veyed in a machine direction, said at least one of a said fiber slurry (24) becomes a fiber web (38) after Yankee roll (52), a suction roll, a hot air hood, a boost said moisture is removed through said forming fabric dryer, an air press, a single pass HPTAD and a two (26). 25 pass HPTAD being downstream in said machine direction from said nip. 13. The apparatus of claim 12, wherein said forming fabric (26) includes a surface having azonally different fabric permeability. Patentansprüche 30 14. The apparatus of claim 12, wherein said structured 1. Verfahren zur Ausbildung einer strukturierten Mate- fabric (28) includes a plurality of valleys (28b) and a rialbahn (38) auf einer Papiermaschine mit den Ver- plurality of peaks (28a). fahrensschritten: Bereitstellung einer Faserstoffsus- pension (24) durch einen Stoffauflauf (22) in einen 15. The apparatus of claim 14, wherein said fiber slurry 35 Spalt, der von einer strukturierten Bespannung (28) (24) substantially covers a portion of a surface of und einem Formiersieb (26) ausgebildet wird; und said structured fabric (28) including at least one of Sammeln von Fasern dieser Faserstoffsuspension said plurality of valleys (28b) and at least one adja- (24) vorwiegend in einer Mehrzahl von Senken (28b) cent peak (28a). dieser strukturierten Bespannung (28), 40 dadurch gekennzeichnet, 16. The apparatus of claim 12, wherein said fiber web dass die aus dieser Faserstoffsuspension (24) ab- (38) has a pillow thickness (C’) associated with said laufende Feuchtigkeit (M) durch das Formiersieb fiber web (38) formed in said valleys (28b), said fiber (26) und nicht durch die strukturierte Bespannung web (38) having a top surface thickness associated (28) läuft und die Faserstoffsuspension (24) nach with said fiber web (38) formed on said peaks (28a), 45 dem Entzug der Feuchtigkeit durch das Formiersieb said pillow thickness (C’) being one of equal to and (26) eine Faserstoffbahn (38) ausbildet. greater than said top surface thickness. 2. Verfahren nach Anspruch 1, wobei dieses Formier- 17. The apparatus of claim 16, further comprising a sieb (26) eine zonal unterschiedliche Siebdurchläs- press section including : a dewatering fabric (82), 50 sigkeit aufweist. said forming fabric (26) being removed from said fiber web (38) and said dewatering fabric (82) contact- 3. Verfahren nach Anspruch 1, wobei diese strukturier- ing said fiber web (38); and a belt press (64) with a te Bespannung (28) eine Mehrzahl von Erhöhungen permeable belt (66) having a fabric tension of greater (28a) aufweistund jeder Erhöhung (28a) mindestens than 30kN/m capable of applying pressure to the 55 eine der mehreren Senken (28b) zugeordnet ist. non-sheet contacting side of the structured fabric (28) such that moisture is drawn from the web (38) 4. Verfahren nach Anspruch 3, wobei die Faserstoff- through the dewatering fabric (82). suspension (24) einen Teilabschnitt einer Oberflä-

9 17 EP 1 709 243 B1 18

che der strukturierten Bespannung (28) wesentlich sen und dass diese Kissenbereiche eingeprägt blei- bedeckt, der mindestens eine dieser mehreren Sen- ben. ken (28b) und mindestens eine angrenzende Erhe- bung (28a) umfasst. 12. Vorrichtung zur Ausbildung einer Faserstoffbahn 5 mit: einem Stoffauflauf (22); einer Formierwalze 5. Verfahren nach Anspruch 4, wobei die Faserstoff- (34); einer strukturierten Bespannung (28); einem suspension (24) über den Verfahrensschritt des Fa- Formiersieb (26), wobei ein Teilabschnitt dieser sersammelns die strukturierte Materialbahn (38) strukturierten Bespannung (28) oder dieses For- ausbildet. miersiebs (26) mit einem Teilabschnitt dieser For- 10 mierwalze (34) in Kontakt steht, eine Seite dieser 6. Verfahren nach Anspruch 5, wobei die strukturierte strukturierten Bespannung (28) und eine Seite die- Materialbahn (38) eine Kissendicke (C’) bezogen auf ses Formiersiebs (26) so zusammenkommen, dass die in den Senken (28b) ausgebildete strukturierte sie einen Spalt ausbilden, der Stoffauflauf (22) eine Materialbahn (38) sowie eine Deckflächendicke be- Faserstoffsuspension (24) in Richtung dieses Spalts zogen auf die an den Erhöhungen (28a) ausgebil- 15 ausbringt, die Faserstoffsuspension (24) Feuchtig- dete strukturierte Materialbahn aufweist, wobei die keit durch das Formiersieb (26) und nicht durch die Kissendicke (C’) gleich der Deckflächendicke ist strukturierte Bespannung verliert und die Faserstoff- oder größer als die Deckflächendicke ist. suspension (24) nach erfolgtem Entzug der Feuch- tigkeit durch das Formiersieb (26) eine Faserstoff- 7. Verfahren nach Anspruch 5, wobei die strukturierte 20 bahn (38) ausbildet. Materialbahn (38) eine Kissenflächenmasse bezogen auf die in den Senken (28b) ausgebildete struk- 13. Vorrichtung nach Anspruch 12, wobei dieses For- turierte Materialbahn (38) sowie eine Deckflächen- miersieb (26) eine Oberfläche mit einer zonal unter- masse bezogen auf die an den Erhöhungen (28a) schiedlichen Siebdurchlässigkeit aufweist. ausgebildete strukturierte Materialbahn (38) auf-25 weist, wobei die Kissenflächenmasse gleich der 14. Vorrichtung nach Anspruch 12, wobei die struktu- Deckflächenmasse ist oder größer als die Deckflä- rierte Bespannung (28) eine Mehrzahl von Senken chenmasse ist. (28b) und eine Mehrzahl von Erhebungen (28a) be- inhaltet. 8. Verfahren nach Anspruch 5, ferner mit den Verfah- 30 rensschritten: Abnehmen des Formiersiebs (26) von 15. Vorrichtung nach Anspruch 14, wobei die Faserstoff- der strukturierten Materialbahn (38); Auflegen der suspension (24) einen Teilabschnitt einer Oberflä- strukturierten Materialbahn (38) auf eine Entwässe- che dieser strukturierten Bespannung (28) wesent- rungsbespannung (82); und Anlegen von Druck an lich bedeckt, dermindestens eineder mehreren Sen- die strukturierte Materialbahn (38) über diese struk- 35 ken (28b) und mindestens eine angrenzende Erhe- turierte Bespannung (28). bung (28a) umfasst.

9. Verfahren nach Anspruch 5, ferner mit dem Verfah- 16. Vorrichtung nach Anspruch 12, wobei die Faserstoff- rensschritt: Anlegen eines negativen Luftdrucks an bahn (38) eine Kissendicke (C’) bezogen auf die in einen Teilabschnitt einer Oberfläche der Entwässe- 40 den Senken (28b) ausgebildete Faserstoffbahn (38) rungsbespannung (82) zum Abzug von Feuchtigkeit sowie eine Deckflächendicke bezogen auf die an aus der strukturierten Materialbahn (38) durch die den Erhebungen (28a) ausgebildete Faserstoffbahn Entwässerungsbespannung (82). (38) aufweist, wobei diese Kissendicke (C’) gleich der Deckflächendikke ist oder größer als die Deck- 10. Verfahren nach Anspruch 5, ferner mit den Verfah- 45 flächendicke ist. rensschritten: Übergabe der strukturierten Material- bahn (38) an einen Yankee- Trockener (52) an einem 17. Vorrichtung nach Anspruch 16, ferner mit einer Pres- Übergabepunkt; und Halten der strukturierten Bahn senpartie mit: einer Entwässerungsbespannung (38) mit der strukturierten Bespannung (28) bis zum (82), wobei das Formiersieb (26) von der Faserstoff- Erreichen dieses Übergabepunktes. 50 bahn (38) abgenommen wird und die Entwässe- rungsbespannung (82) in Kontakt mit der Faserstoff- 11. Verfahren nach Anspruch 10, wobei die strukturierte bahn (38) tritt; und eine Bandpresse (64) mit einem Materialbahn (38) bis zu diesem Übergabepunkt auf durchlässigen Band (66), das eine Bandspannung der strukturierten Bespannung (28) verbleibt, wo- von über 30 kN/m besitzt und das Anlegen eines durch sichergestellt wird, dass in den Senken (28b) 55 Drucks an die nicht die Materialbahn berührende ausgebildete Kissenbereiche der strukturierten Ma- Seite der strukturierten Bespannung (28) gestattet, terialbahn (38) eine höhere Flächenmasse als die so dass Feuchtigkeit aus der Materialbahn (38) verbleibende strukturierte Materialbahn (38) aufwei- durch die Entwässerungsbespannung (82) abgezo-

10 19 EP 1 709 243 B1 20

gen wird. (28a), chacun desdits pics (28a) étant associé à au moins une de ladite pluralité de vallées (28b). 18. Vorrichtung nach Anspruch 17, ferner mit einer Va- kuumeinrichtung, die einen negativen Luftdruck an 4. Procédé selon la revendication 3, dans lequel ladite einen Teilabschnitt einer Oberfläche der Entwässe- 5 suspension de fibres (24) couvre sensiblement une rungsbespannung (82) anlegt und so der Faserstoff- partie d’une surface de ladite toile structurée (28) bahn (38) durch die Entwässerungsbespannung comprenant au moins une de ladite pluralité de val- (82) Feuchtigkeit entzieht. lées (28b) et au moins un pic adjacent (28a).

19. Vorrichtung nach Anspruch 18, wobei diese Vaku- 10 5. Procédé selon la revendication 4, dans lequel ladite umeinrichtung eine Saugwalze (60) ist. suspension de fibres (24) devient la nappe structu- rée (38) à la suite de ladite étape de collecte. 20. Vorrichtung nach Anspruch 12, ferner mit einem Schuhpressenbelt (64) in Teilkontakt mit einer an- 6. Procédé selon la revendication 5, dans lequel la nap- deren Seite dieser strukturierten Bespannung (28). 15 pe structurée (38) a une épaisseur de coussin (C’) associée à la nappe structurée (38) formée dans les- 21. Vorrichtung nach Anspruch 20, ferner mit einer Luft- dites vallées (28b), la nappe structurée (38) ayant durchströmungseinrichtung (68), die zusätzlich Luft une épaisseur de surface supérieure associée à la durch den Schuhpressenbelt (64) hindurchführt. nappe structurée (38) formée sur lesdits pics (28a), 20 ladite épaisseur de coussin (C’) étant égale ou su- 22. Vorrichtung nach Anspruch 12, ferner mit minde- périeure à ladite épaisseur de surface supérieure. stens einer der folgenden Einrichtungen: Yankee- Zylinder (52), Saugwalze (60), Heißlufthaube (54), 7. Procédé selon la revendication 5, dans lequel la nap- Boost-Dryer-Trocknungsaggregat, Luftpresse, pe structurée (38) a un poids de base de coussin HPTAD-Trockner und/oder Zweifach-HPTAD- 25 associé à la nappe structurée (38) formée dans les- Trockner, wobei die Faserstoffbahn (38) sich in einer dites vallées (28b), la nappe structurée (38) ayant Maschinenlaufrichtung bewegt und die genannten un poids de base de surface supérieure associé à Einrichtungen Yankee-Zylinder (52), Saugwalze, la nappe structurée (38) formée sur lesdits pics Heißlufthaube, Boost-Dryer-Trocknungsaggregat, (28a), ledit poids de base du coussin étant égal ou Luftpresse, Einfach-HPTAD-Trockner und/oder 30 supérieur audit poids de base de surface supérieure. Zweifach-HPTAD-Trockner dem Spalt in Maschi- nenlaufrichtung nachgeschaltet sind. 8. Procédé selon la revendication 5, comprenant en outre les étapes suivantes : retrait de ladite toile de formation (26) de la nappe structurée (38) ; mise en Revendications 35 contact de la nappe structurée (38) avec une toile d’égouttage (82) ; et application d’une pression à la 1. Procédé de formation d’une nappe structurée (38) à nappe structurée (38) à travers ladite toile structurée l’aide d’une machine à papier, comprenant les éta- (28). pes suivantes : fourniture d’une suspension de fibres (24) à travers une caisse de tête (22) à un intervalle 40 9. Procédé selon la revendication 5, comprenant en de pincement formé par une toile structurée (28) et outre l’étape d’application d’une pression d’air né- une toile de formation (26) ; et collecte de fibres de gative contre une partie d’une surface de ladite toile ladite suspension de fibres (24) principalement dans d’égouttage (82), éliminant de la sorte l’humidité de une pluralité de vallées (28b) de ladite toile structu- la nappe structurée (38) à travers ladite toile d’égout- rée (28), caractérisé en ce que l’humidité (M) qui 45 tage (82). quitte ladite suspension de fibres (24) se déplace à travers ladite toile de formation (26) et pas à travers 10. Procédé selon la revendication 5, comprenant en ladite toile structurée (28) et ladite suspension de outre les étapes suivantes : transfert de la nappe fibres (24) devient une nappe fibreuse (38) après structurée (38) à un sécheur frictionneur (52) en un élimination de ladite humidité à travers ladite toile de 50 point de transfert ; et retenue de la nappe structurée formation (26). (38) avec ladite toile structurée (28) jusqu’à ce que ledit point de transfert soit atteint. 2. Procédé selon la revendication 1, dans lequel ladite toile de formation (26) a une perméabilité de toile 11. Procédé selon la revendication 10, dans lequel la différente selon les zones. 55 nappe structurée (38) reste sur ladite toile structurée (28) jusqu’audit point de transfert, assurant de la sor- 3. Procédé selon la revendication 1, dans lequel ladite te que les zones de coussin de la nappe structurée toile structurée (28) comprend une pluralité de pics (38) formée dans lesdites vallées (28b) aient un

11 21 EP 1 709 243 B1 22

poids de base supérieur à celui du reste de la nappe 18. Appareil selon la revendication 17, comprenant en structurée (38) et que lesdites zones de coussin res- outre un dispositif à vide appliquant une pression tent pressées. d’air négative contre une partie d’une surface de ladite toile d’égouttage (82), retirant de la sorte l’hu- 12. Appareil formateur de nappe fibreuse, comprenant : 5 midité de ladite nappe fibreuse (38) à travers ladite une caisse de tête (22) ; un rouleau formateur (34) ; toile d’égouttage (82). une toile structurée (28) ; une toile de formation (26), une partie de l’une de ladite toile structurée (28) et 19. Appareil selon la revendication 18, dans lequel ledit de ladite toile de formation (26) en contact avec une dispositif à vide est un rouleau à vide (60). partie dudit rouleau formateur (34), un côté de ladite 10 toile structurée (28) et un côté de ladite toile de for- 20. Appareil selon la revendication 12, comprenant en mation (26) se rapprochant l’un de l’autre, formant outre une courroie de presse (64) à intervalle de pin- ainsi un intervalle de pincement, ladite caisse de tête cement étendu, en contact partiel avec un autre côté (22) déchargeant une suspension de fibres (24) di- de ladite toile structurée (28). rigée sur ledit intervalle de pincement, ladite suspen- 15 sion de fibres (24) perdant de l’humidité à travers 21. Appareil selon la revendication 20, comprenant en ladite toile de formation (26) et pas à travers ladite outre un dispositif d’écoulement d’air (68) faisant de toile structurée et ladite suspension de fibres (24) plus passer de l’air à travers ladite courroie de presse devient une nappe fibreuse (38) après que ladite hu- (64) à intervalle de pincement étendu. midité a été retirée à travers ladite toile de formation 20 (26). 22. Appareil selon la revendication 12, comprenant en outre au moins un des éléments suivants : un cylin- 13. Appareil selon la revendication 12, dans lequel ladite dre frictionneur (52), un rouleau d’aspiration (60), toile de formation (26) comprend une surface ayant une hotte à air chaud (54), un sursécheur, une pres- une perméabilité de toile différente selon la zone. 25 se à air, un HPTAD et un HPTAD à deux passages, ladite nappe fibreuse (38) étant acheminée dans le 14. Appareil selon la revendication 12, dans lequel ladite sens machine, ledit au moins un élément parmi un toile structurée (28) comprend une pluralité de val- cylindre frictionneur (52), un rouleau d’aspiration, lées (28b) et une pluralité de pics (28a). une hotte à air chaud, un sursécheur, une presse à 30 air, un HPTAD à passage unique et un HPTAD à 15. Appareil selon la revendication 14, dans lequel ladite deux passages étant en aval dans ledit sens machi- suspension de fibres (24) couvre sensiblement une ne par rapport audit intervalle de pincement. partie d’une surface de ladite toile structurée (28) comprenant au moins l’une de ladite pluralité de val- lées (28b) et au moins un pic adjacent (28a) . 35

16. Appareil selon la revendication 12, dans lequel la nappe fibreuse (38) a une épaisseur de coussin (C’) associée à ladite nappe fibreuse (38) formée dans lesdites vallées (28b), ladite nappe fibreuse (38)40 ayant une épaisseur de surface supérieure associée à ladite nappe fibreuse (38) formée sur lesdits pics (28a), ladite épaisseur de coussin (C’) étant égale ou supérieure à ladite épaisseur de surface supé- rieure. 45

17. Appareil selon la revendication 16, comprenant en outre une section de presse contenant : une toile d’égouttage (82), ladite toile de formation (26) étant retirée de ladite nappe fibreuse (38) et ladite toile 50 d’égouttage (82) étant en contact avec ladite nappe fibreuse (38) ; et une presse à courroie (64) avec une courroie perméable (66) ayant une tension de toile supérieure à 30 kN/m capable d’appliquer une pression au côté du tissu structuré (28) ne touchant 55 pas la feuille de sorte que cette humidité soit aspirée de la nappe (38) à travers la toile d’égouttage (82).

12 EP 1 709 243 B1

13 EP 1 709 243 B1

14 EP 1 709 243 B1

15 EP 1 709 243 B1

16 EP 1 709 243 B1

17 EP 1 709 243 B1

18 EP 1 709 243 B1

19 EP 1 709 243 B1

20 EP 1 709 243 B1

REFERENCES CITED IN THE DESCRIPTION

This list of references cited by the applicant is for the reader’s convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.

Patent documents cited in the description

• WO 03062528 A1 [0002] • GB 2324314 A [0005] • US 4191609 A [0002] • US 5503715 A [0005] • WO 0300002 A [0004] • EP 2004053688 W [0045] [0047] • US 20030102098 A [0004] • EP 2005050198 W [0045] [0047] • US 5277761 A [0005] • US 6237644 B [0059]