EP0987366A2 - Pressfilz mit verbesserter Entwasserung - Google Patents

Pressfilz mit verbesserter Entwasserung Download PDF

Info

Publication number
EP0987366A2
EP0987366A2 EP99117832A EP99117832A EP0987366A2 EP 0987366 A2 EP0987366 A2 EP 0987366A2 EP 99117832 A EP99117832 A EP 99117832A EP 99117832 A EP99117832 A EP 99117832A EP 0987366 A2 EP0987366 A2 EP 0987366A2
Authority
EP
European Patent Office
Prior art keywords
layer
press felt
press
batt
paper
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP99117832A
Other languages
English (en)
French (fr)
Other versions
EP0987366A3 (de
Inventor
Eugene Fekete
Kurt Wiebe
Samuel M. Baker
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Jwi Ltd
Original Assignee
Jwi Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Jwi Ltd filed Critical Jwi Ltd
Publication of EP0987366A2 publication Critical patent/EP0987366A2/de
Publication of EP0987366A3 publication Critical patent/EP0987366A3/de
Withdrawn legal-status Critical Current

Links

Images

Classifications

    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
    • D21F1/00—Wet end of machines for making continuous webs of paper
    • D21F1/0027—Screen-cloths
    • D21F1/0063—Perforated sheets
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
    • D21F7/00—Other details of machines for making continuous webs of paper
    • D21F7/08—Felts
    • D21F7/083—Multi-layer felts

Definitions

  • This invention is concerned with composite fabrics known as "press felts" used in the press section of a paper making machine.
  • the wet paper web is carried by at least one press felt, upon which the wet paper is passed through at least one nip between either a pair of rotating opposed rollers, or between a single rotating roller and a device known as a "shoe", in what is known as a shoe press.
  • a shoe press a device known as a "shoe"
  • the press felt carrying the wet paper web is exposed to compressive pressures ranging from about 3MPa to at least about 18MPa.
  • the applied pressure serves to expel a proportion of the water in the wet paper web; the expelled water is the carried away by the press felt.
  • the paper consistency which is defined as the percentage by weight of paper making solids in the web, will increase from a value as low as 15% on entry to the press section, to a value of the order of 60%.
  • the press felt In addition to resisting the imposed compressive forces and permitting transport of the expelled water, the press felt must also be able to resist and contain the forces imposed upon it in order to move the press felt, and the paper web carried by it, through the paper making machines: modern paper making machines can operate at a linear speed in excess of 75kph.
  • the known press felts are generally comprised of essentially two components, a core fabric and an absorbent layer or layers.
  • the core fabric is frequently a woven fabric, although other structures are known.
  • the core fabric is structured to accommodate the mechanical stresses imposed in order to move the press felt, to resist undue compaction as it passes through the nip or nips, and to support the absorbent layer.
  • the absorbent layer is generally at least one layer of fibrous batt, typically applied to the core fabric by a needle punching process.
  • the absorbent layer may also comprise a porous foam or other material having sufficient strength, resistance to compaction, and void volume so as to be effective in a press felt. If an absorbent layer is attached to only one surface of the core fabric, it will typically be applied to the paper side surface of the core fabric.
  • successive batt layers may be comprised of relatively finer fibres. This will increase the smoothness of the paper side of the press felt. It is also known to mix yarn sizes within one or more layers.
  • the paper side surface of a press felt should provide as high a degree as possible of contact between the paper side surface of the press felt and the wet paper web, so as to provide, amongst other things, good support to the wet paper web in the press nip.
  • a high degree of contact also promotes uniform dewatering of the wet paper web.
  • a common means of improving the degree of contact between the paper side surface of the batt and the wet paper web is to needle, or otherwise attach, a so-called capping layer of fine batt fibres onto the paper side surface of the batt.
  • the batt fibres are more or less randomly oriented so that on a macro scale the batt appears to be isotropic.
  • On a micro scale at the paper side surface of the batt that is in contact with the wet paper web in the nip, this is not the case.
  • the distribution of contact points is found to be irregular. There are regions in the paper side surface of the batt which provide relatively large numbers of contact points between the paper side surface of the batt and the wet paper web, and there are other regions in which the number of contact points is fewer.
  • the support provided to the wet paper, particularly for both light weight paper sheets, and relatively dry paper sheets (which are thinner) is far from optimal, as the points of support are still somewhat randomly scattered. Furthermore, the use of smaller fibres results in high press felt wear, thus unduly diminishing the working life of the press felt.
  • this invention seeks to provide a composite press felt, comprising at least three layers wherein:
  • the core fabric is a woven fabric. More preferably, the core fabric comprises a single layer or a multilayer woven fabric.
  • the second layer comprises one or more layers of batt material attached by needling to the first layer. More preferably, the second layer comprises at least two layers of batt material.
  • the third layer is chosen from the group consisting of: a fine woven fabric; a porous film sheet; and a porous film obtained by heating a layer of an at least partially fusible powder material applied to the paper side surface of the third layer.
  • the distance between adjacent contact points between the wet paper web and the paper side surface of the porous layer is approximately equal to the thickness of the wet paper web at mid-nip as it passes through the press. More preferably, the distance between adjacent contact points between the wet paper web and the paper side surface of the porous layer is from about 25% to about 100% of the thickness of the wet paper web at mid-nip as it passes through the press.
  • FIG. 1 there is shown a photograph of the paper side surface of a press felt that is exposed to 6.3 MPa pressure so as to duplicate the effect experienced by the press felt at the midpoint of a typical press nip.
  • the photograph is a 100x magnification of the batt surface, which is comprised of very fine, 6.7 dtex fibres; the batt has been needled to a standard, double layer woven base fabric.
  • the dark regions of the photograph show areas of contact between the batt and the nip, while the white areas are effectively drainage openings into the batt structure below this surface.
  • the photograph thus depicts the interface between the paper side surface of the batt and wet paper web as they pass together through the press nip.
  • the batt fibres appear to be randomly located and thus uniformly dispersed.
  • Figure 1 shows that, on a microscopic scale, the batt fibres 1 are not randomly and uniformly dispersed; the contact areas and drainage openings on the surface interface of the batt and the wet paper web are in fact unevenly dispersed on the paper side surface of the batt.
  • the photograph clearly shows a concentration of contact points at A, an absence of contact points at C, and an intermediate number at B.
  • Figure 2 is a 100x magnification photomicrograph of the paper side surface of a uniformly porous surface layer such as would be used in the press felts of the present invention.
  • the porous layer is a 400 mesh (157.5 strands per cm) stainless steel woven fabric, the individual strands of which are 26 microns in diameter (roughly equivalent to a size of 10 dtex).
  • This fabric was obtained from F.P. Smith Wire Cloth Co. of Northlake, IL. It was then attached to a rubber backing and pressed at 6.3 MPa using the same laboratory press as was used to obtain the photograph of Figure 1.
  • the rubber backing was provided to assist in simulating the compression characteristics of a press felt upon which the porous layer would normally be attached in the fabrics of this invention.
  • the porous layer would be laid over the absorbent layer.
  • Figure 2 is intended to illustrate the uniform distribution of equally spaced contact points and drainage openings at the interface between the fabric and a web in the nip.
  • Figure 3 is intended to represent a high magnification cross section taken from the paper side surface toward the machine side surface through a uniformly porous fabric located on the paper side surface of a press felt batt.
  • the uniformly porous fabric is indicated generally at 7
  • the press felt batt is 2
  • contact regions in the porous fabric are shown as 3
  • drainage openings in this fabric are indicated at 4
  • 5 designates the random fibres in the paper side surface of the batt shown generally as 2.
  • the porous fabric 1 may be a woven structure, a perforated film, or porous film obtained by heating a layer of at least partially fusible powder material.
  • the porous layer in the press felts of this invention can take several forms, and can be attached to the batt surface in several ways.
  • the porous layer comprises a fabric which is applied to the exposed face of the batt, and attached to the batt by any suitable means, such as gluing.
  • a relatively narrow fabric strip can be used, which is attached to the core fabric using a spiral winding technique, essentially as described by Best et at US 5,268,076 or by Rexfelt, US 5,360,656.
  • a porous film is used, which can be applied by the same techniques as are used for a porous fabric layer.
  • the film as applied can also be non-porous, and is rendered porous after attachment to the batt either by mechanical means or by removal of a labile component under the influence of heat or a solvent.
  • a powder material is applied to the batt porous layer surface, and converted into a porous film by heating.
  • the film can be applied to the full width of the pressfelt, or a variation of the Best et al. or Rexfelt techniques can be employed.
  • the test unit 10 contains a pair of opposed rolls 11, 12 which are urged together to provide the required nip pressure by a force applied essentially in the direction of the arrow 13.
  • the test sample of press felt 14 is looped around only the lower roll 12.
  • the test samples of paper are contained in the wet tray 15, and transferred by hand onto the press felt under test.
  • the press felt sample circulates past the guides 16, 17 to maintain its alignment in the test unit.
  • the doctor blade 20 serves to remove excess surface water from the surface of the roll 11 after is has passed through the roll nip.
  • the pair of rolls 11, 12 rotate in the directions indicated by the arrows 18, 19. Both the speed of rotation of the rolls, and the applied load, can be separately varied.
  • the test procedure is as follows. A supply of paper, typically a sheet (or sheets) of a newsprint grade of about 50 gsm, about 38mm x 25mm in size and of a known weight per sheet, is presoaked overnight in de-ionised water. The press felt sample is cut to provide a belt of appropriate length and about 100mm in width. The belt is then placed on the test unit and preconditioned by circulation through the roll nip saturated with water and under a line load of 26kN/m. The belt typically completes from about 9,000 - 10,000 rotation cycles prior to testing. The felt is then allowed to dry until a moisture level of 30 - 35% is reached.
  • a supply of paper typically a sheet (or sheets) of a newsprint grade of about 50 gsm, about 38mm x 25mm in size and of a known weight per sheet
  • the press felt sample is cut to provide a belt of appropriate length and about 100mm in width.
  • the belt is then placed on the test unit and preconditioned by circulation through the roll nip saturated with
  • the wet paper sample is blotted to remove excess free water, placed on the test felt, and passed through the roll nip at the desired nip load and press felt speed. After removal from the top roll 11 by the doctor blade, the wet sheet is reweighed to determine its consistency.
  • the porous layer was a layer of stainless steel fabric woven in a plain weave with a mesh count of about 16 wires/mm, woven from wires with a diameter of about 0.028mm. Comparison of the exit paper consistency from the test unit with the fabric in place, compared to paper consistency without the fabric in place, showed a reproducible improvement in paper consistency of between 3% and at least 5%.

Landscapes

  • Paper (AREA)
EP99117832A 1998-09-14 1999-09-09 Pressfilz mit verbesserter Entwasserung Withdrawn EP0987366A3 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US152194 1988-02-04
US15219498A 1998-09-14 1998-09-14

Publications (2)

Publication Number Publication Date
EP0987366A2 true EP0987366A2 (de) 2000-03-22
EP0987366A3 EP0987366A3 (de) 2000-04-05

Family

ID=22541888

Family Applications (1)

Application Number Title Priority Date Filing Date
EP99117832A Withdrawn EP0987366A3 (de) 1998-09-14 1999-09-09 Pressfilz mit verbesserter Entwasserung

Country Status (2)

Country Link
EP (1) EP0987366A3 (de)
CA (1) CA2282053A1 (de)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2004085727A3 (en) * 2003-03-25 2004-11-11 Voith Fabrics Patent Gmbh Composite press felt
EP1637647A1 (de) * 2004-09-17 2006-03-22 Voith Fabrics Patent GmbH Verfahren zur Herstellung einer Papiermaschinenbespannung
DE102007000578A1 (de) 2007-10-26 2009-04-30 Voith Patent Gmbh Papiermaschinenbespannungen, insbesondere für Pressfilze, und Verfahren zu deren Herstellung
US8152964B2 (en) 2007-12-21 2012-04-10 Voith Patent Gmbh Press fabric for a machine for the production of web material
CN118386628A (zh) * 2024-03-26 2024-07-26 湖北中烟工业有限责任公司 一种用于造纸法再造烟叶靴式压榨毛毯及其制备方法和应用

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3772746A (en) * 1970-01-07 1973-11-20 Orr Felt Co Method of making papermaker{3 s felt
SE429769B (sv) * 1980-04-01 1983-09-26 Nordiskafilt Ab Arkaggregat och sett att tillverka detsamma
FI77907C (fi) * 1985-08-23 1989-05-10 Tamfelt Oy Ab Pressfilt.
US5071697A (en) * 1990-01-22 1991-12-10 Appleton Mills Structure for extracting water from a paper web in a papermaking process
US5360518A (en) * 1991-12-18 1994-11-01 Albany International Corp. Press fabrics for paper machines

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2004085727A3 (en) * 2003-03-25 2004-11-11 Voith Fabrics Patent Gmbh Composite press felt
US7871672B2 (en) 2003-03-25 2011-01-18 Voith Patent Gmbh Composite press felt
EP1637647A1 (de) * 2004-09-17 2006-03-22 Voith Fabrics Patent GmbH Verfahren zur Herstellung einer Papiermaschinenbespannung
DE102007000578A1 (de) 2007-10-26 2009-04-30 Voith Patent Gmbh Papiermaschinenbespannungen, insbesondere für Pressfilze, und Verfahren zu deren Herstellung
US8152964B2 (en) 2007-12-21 2012-04-10 Voith Patent Gmbh Press fabric for a machine for the production of web material
CN118386628A (zh) * 2024-03-26 2024-07-26 湖北中烟工业有限责任公司 一种用于造纸法再造烟叶靴式压榨毛毯及其制备方法和应用
CN118386628B (zh) * 2024-03-26 2026-02-06 湖北中烟工业有限责任公司 一种用于造纸法再造烟叶靴式压榨毛毯及其制备方法和应用

Also Published As

Publication number Publication date
CA2282053A1 (en) 2000-03-14
EP0987366A3 (de) 2000-04-05

Similar Documents

Publication Publication Date Title
FI64960C (fi) Transportfilt foer papperstillverkning och foerfarande foer des tillverkning
KR930010748B1 (ko) 제지기용 코팅프레스 패브릭 및 그 제조방법
US4503113A (en) Papermaker felt with a three-layered base fabric
FI96624B (fi) Paperikoneen kangas
FI95613C (fi) Paperinvalmistushuopa, menetelmä paperinvalmistushuovan valmistamiseksi sekä menetelmä märän paperirainan kuivaamiseksi
EP2508673A2 (de) Pressfilz
JP4102644B2 (ja) 抄紙用プレスフェルト及び抄紙機用プレス装置
JPH0621432B2 (ja) 拡張ニッププレスにおけるベルト
EP0995835A1 (de) Fasern mit verbesserten Entwasserungseigenschaften für Pressfilzen
RU2276213C2 (ru) Прессовальная ткань
EP0987366A2 (de) Pressfilz mit verbesserter Entwasserung
JP4627137B2 (ja) 湿紙搬送用ベルト
JP4454408B2 (ja) 抄紙用フェルト
US4882217A (en) Needled press felt
EP2213788A1 (de) Trägerband für nasse papierbahn
US7132036B2 (en) Dewatering of a paper web in a press section of a papermaking machine
EP2206828A1 (de) Band zur förderung von nassvlies
US20070240844A1 (en) Paper Transporting Felt and Press Apparatus of Paper Machine Having the Paper Transporting Felt
JP4712508B2 (ja) シュープレス用の抄紙搬送フェルトおよび該抄紙搬送フェルトを備えたシュープレス型抄紙機のプレス装置
JP4480006B2 (ja) シュープレス用の抄紙搬送フェルトおよび該抄紙搬送フェルトを備えたシュープレス型抄紙機のプレス装置
EP4621126A1 (de) Papiermaschinenfilz und verfahren zur herstellung eines papiermaschinenfilzes
KR20060055396A (ko) 초지반송펠트 및 상기 초지반송펠트를 구비한 초지기의프레스 장치
EP2902545B1 (de) Transferband zur Überführung einer nassen Papierbahn
US20080190510A1 (en) High density press fabric
CA1317144C (en) Needled press felt

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

PUAL Search report despatched

Free format text: ORIGINAL CODE: 0009013

AK Designated contracting states

Kind code of ref document: A2

Designated state(s): AT BE CH CY DE DK ES FI FR GB GR IE IT LI LU MC NL PT SE

AX Request for extension of the european patent

Free format text: AL;LT;LV;MK;RO;SI

AK Designated contracting states

Kind code of ref document: A3

Designated state(s): AT BE CH CY DE DK ES FI FR GB GR IE IT LI LU MC NL PT SE

AX Request for extension of the european patent

Free format text: AL;LT;LV;MK;RO;SI

17P Request for examination filed

Effective date: 20000817

AKX Designation fees paid

Free format text: AT BE CH CY DE DK ES FI FR GB GR IE IT LI LU MC NL PT SE

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN

18D Application deemed to be withdrawn

Effective date: 20020403