Apparatus for and Process of Material Web Formation
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(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 con- junction 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.