EP0687770A2 - Verfahren zum Beschichten einer Papierbahn - Google Patents

Verfahren zum Beschichten einer Papierbahn Download PDF

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Publication number
EP0687770A2
EP0687770A2 EP95201470A EP95201470A EP0687770A2 EP 0687770 A2 EP0687770 A2 EP 0687770A2 EP 95201470 A EP95201470 A EP 95201470A EP 95201470 A EP95201470 A EP 95201470A EP 0687770 A2 EP0687770 A2 EP 0687770A2
Authority
EP
European Patent Office
Prior art keywords
coating
web
doctor
levelling
procedure
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Withdrawn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
EP95201470A
Other languages
English (en)
French (fr)
Other versions
EP0687770A3 (de
Inventor
Markku Niemi
Markus Mannström
Matti Pouhakka
Olli Aalto
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.)
KESKUSLABORATORIO - CENTRALLABORATORIUM Oy AB
Original Assignee
KESKUSLABORATORIO - CENTRALLABORATORIUM Oy AB
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 KESKUSLABORATORIO - CENTRALLABORATORIUM Oy AB filed Critical KESKUSLABORATORIO - CENTRALLABORATORIUM Oy AB
Publication of EP0687770A2 publication Critical patent/EP0687770A2/de
Publication of EP0687770A3 publication Critical patent/EP0687770A3/de
Withdrawn legal-status Critical Current

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Classifications

    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H25/00—After-treatment of paper not provided for in groups D21H17/00 - D21H23/00
    • D21H25/08—Rearranging applied substances, e.g. metering, smoothing; Removing excess material

Definitions

  • the present invention concerns a procedure for coating a paper web, wherein coating material is applied on the surface of the web which is run at high speed and the coating is levelled by scraping.
  • the invention relates to a procedure for coating a paper web, the running speeds being high, that is in excess of 1000 m/min, advantageously over 1200 m/min, even higher than 1400 m/min, up to the speed of 2000 m/min or even beyond.
  • paper is understood to be printing paper, e.g. MWC and LWC paper brands, especially printing papers with wood content having a base mass on the order of 30 to 70 g/m2.
  • the object of the present invention is to eliminate the drawbacks discussed in the foregoing. It is a specific object of the invention to disclose a novel procedure for coating a paper web by using which such coating can be done at high running speed.
  • the object of the invention is to disclose a novel paper coating procedure which is applicable in coating printing papers containing wood, e.g. MWC and LWC paper brands, base mass of the base paper advantageously in the range of 30 to 70 g/m2.
  • the invention is based on the fact observed in studies that have been made, that when pre-levelling of the coating (the first step) is carried out immediately upon coating, by means of scraping with a pre-doctor, so that the coating quantity remaining on the web will be 12 to 30 g/m2, advantageously 12 to 30 g/m2. and steam is conducted onto the web and the coating levelled with the aid of a pre-doctor is levelled with the aid of a doctor blade (second step) so that the quantity of coating remaining on the web after levelling will be 6 to 14 g/m2, the coating meets the desired quality criteria, that is desired gloss, calendering properties etc. characteristics are attained. Furthermore, when the procedure of the invention is employed, no doctor beard will form on the pre-doctor and/or the scraping doctor, which would constitute a factor limiting runability in connection with coating using existing procedures.
  • the invention is largely based on the circumstance that in the procedure of the invention the paste quantity remaining on the web in the first step thereof is so thin, that is 12 to 30 g/m2, that steam can be added on the surface of the web, whereby the moisture gradient of the web is changed so that the formation of doctor beard becomes controllable, that is no doctor beard interfering with runability forms on the pre-doctor or on the scraping doctor. If steam is conducted onto the web surface in a conventional paper web coating procedure, such addition of steam usually does not usually improve the runabillty of the web, that is the steam added is no help in view of runability of the web.
  • the mode of application of the coating on the web may be any mode of application previously known in itself. Therefore the procedure suits to be used e.g. in connection with application by means of an applicator roll, with nozzle application (in which case the edge of the nozzle adjacent to the web may constitute the pre-doctor), or in general with any mode of coating known in itself in the art.
  • the essential feature of the procedure is that in the second levelling step coating is removed from the surface of the paper web, at the same time levelling the remaining coating.
  • the steaming can be done close to the pre-doctor or close to the scraping doctor, or anywhere between the two. It should be noted in connection with steaming that a large quantity of steam reduces the dry matter content of the paste.
  • the steam quantity may thus advantageously be selected to be such that it will not substantially reduce the dry matter content of the coating paste.
  • the effect of the steam can be enhanced by directing the steam onto the web surface by the aid of a special housing, which constitutes a housing confining the web on one side thereof from one margin to the other, and which is sealed with the walls of the housing against the margins of the counter-roll, over a given distance, e.g. 0.05 to 0.7 m or more in the direction of travel of the web.
  • a special housing which constitutes a housing confining the web on one side thereof from one margin to the other, and which is sealed with the walls of the housing against the margins of the counter-roll, over a given distance, e.g. 0.05 to 0.7 m or more in the direction of travel of the web.
  • Levelling of the coating with the pre-doctor that is the first levelling step, and levelling of the coating remaining on the web surface and partial removal of the coating, the second scraping step, are advantageously performed against one and the same counter-roll so that the counter-roll braces the web in relation to the coating from the side opposite thereto.
  • Levelling the coating with the aid of a scraping doctor, the second levelling step is advantageously performed immediately after the levelling effected with the aid of the pre-doctor, the first step, e.g. up to 5 cm to 0.7 m (even up to 2 m) after the pre-doctor.
  • the coating material When the procedure of the invention is applied, the coating material will form a coating more coherent and presenting better quality than before.
  • the procedure is fit to be used in connection with coatings of any kind of paper known in the art.
  • Figs 1-2 the endless paper web moving in a paper machine in travelling direction a has been conducted to run against a counter-roll 2, partly lapping this roll and being braced by it.
  • coating is applied with the aid of an applicator 3, in a way known in itself in the art.
  • a pre-doctor 4 has been provided, which levels the coating applied on the web surface so that the quantity of coating remaining on the web surface will be 12 to 30 g/m2, advantageously 12 to 20 g/m2.
  • steam is conducted onto the surface of the web, e.g. with the aid of a steam nozzle 5. The steam travels a certain distance along with the web and acts on the coating which was levelled in the first levelling step.
  • the web and the coating applied on its surface, levelled and steamed go to the second levelling step, in which the coating is scraped with the aid of a scraping doctor 6 so that the quantity of coating remaining on the web after levelling is 6 to 14 g/m2.
  • the second levelling step part of the coating is removed from the web surface and, at the same time, the coating is levelled once again.
  • the quality of the coating thus obtained on the paper is high-standard of its quality criteria, and of prime quality.
  • the first coating step has been implemented with the aid of a conventional applicator roll 3.
  • coating material is applied onto the surface of the applicator roll 3 e.g. from a trough 7.
  • the pre-doctor 4 removes the excess of coating material, which is returned to circulation, that is into the trough 7.
  • Fig. 1 the steaming has been implemented with the aid of a special housing 8, surrounding the web on its side opposite to its bracing roll 2.
  • the steaming housing 8 aids the deposition of steam on the web surface and, thus, its moistening effect on the coating. Furthermore, the steam, obviously owing to said moistening effect, prevents any doctor beard from forming on the scraping doctor 6; such a beard would otherwise constitute a factor generally limiting the coating process.
  • the first step coating is implemented, using so-called nozzle coating.
  • the edge of the nozzle, in the travelling direction a , on the underside constitutes in this case the pre-doctor levelling the coating.
  • the speed of the paper web in a procedure as shown in Figs 1-2 may vary e g. over 1000 m/min, advantageously over 1200 m/min, up to e.g. 2000 m/min, and even beyond.
  • test running speed was 1200 m/min in the steam tests.
  • the coating quantity objective was 10 g/m2 in the first and second coating steps.
  • the test running speed was 1200 m/min in the reference test.
  • the dry matter content of the paste in the machine circulation did not change in the application step during the run, although various test plots were run for about 15 to 20 min. with the same paste. In particular during steaming no changes were noticed in the paste dry matter.
  • the paste dry matter content was 62.6% by weight at commencement and 62.4% by weight on termination of the entire run. In the paste sample from the second scraping doctor the steam effect was observed.
  • the dry matter content of the paste being scraped diminished about 2.5% by weight (initial value 62.6, sample about 60% by weight). The moisture was presumably on the surface of the scraped paste.
  • the quantity of coating measured on the surface of the paper was 10 g/m2.
  • the moisture gradient required for supply was achieved by conducting steam through a nozzle, after the pre-doctor, onto the paste surface about 0.6 kg H2O per minute and metre of breadth.

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  • Paper (AREA)
EP95201470A 1994-06-07 1995-06-06 Verfahren zum Beschichten einer Papierbahn Withdrawn EP0687770A3 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FI942688 1994-06-07
FI942688A FI96893C (fi) 1994-06-07 1994-06-07 Menetelmä paperirainan päällystämiseksi

Publications (2)

Publication Number Publication Date
EP0687770A2 true EP0687770A2 (de) 1995-12-20
EP0687770A3 EP0687770A3 (de) 1997-05-21

Family

ID=8540871

Family Applications (1)

Application Number Title Priority Date Filing Date
EP95201470A Withdrawn EP0687770A3 (de) 1994-06-07 1995-06-06 Verfahren zum Beschichten einer Papierbahn

Country Status (2)

Country Link
EP (1) EP0687770A3 (de)
FI (1) FI96893C (de)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0823509A2 (de) * 1996-08-09 1998-02-11 Cartiere Burgo S.p.A. Papierbeschichtungsvorrichtung
EP0911446A2 (de) * 1997-10-24 1999-04-28 Voith Sulzer Papiertechnik Patent GmbH Verfahren und Vorrichtung zur Beaufschlagung einer Papier- oder Kartonbahn mit einem flüssigen oder pastösen Auftragsmedium
DE19824804A1 (de) * 1998-06-03 1999-12-09 Voith Sulzer Papiertech Patent Verfahren und Vorrichtung zur Oberflächenbehandlung einer Papierbahn
EP1113108A2 (de) * 1999-12-24 2001-07-04 VITS-Maschinenbau GmbH Anlage zum Imprägnieren von durlaufenden Bahnen
EP1607521A1 (de) * 2004-06-17 2005-12-21 Voith Paper Patent GmbH Auftragsvorrichtung

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3970039A (en) * 1975-09-18 1976-07-20 American Tara Corporation High speed carbonizing machine
DE3146382A1 (de) * 1980-11-28 1982-10-07 Valmet Oy, 00130 Helsinki Oberflaechenleimungs- und/oder streichvorrichtung fuer eine papierbahn oder dergleichen
JPH03193157A (ja) * 1989-12-21 1991-08-22 Fuji Photo Film Co Ltd 塗布方法

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3970039A (en) * 1975-09-18 1976-07-20 American Tara Corporation High speed carbonizing machine
DE3146382A1 (de) * 1980-11-28 1982-10-07 Valmet Oy, 00130 Helsinki Oberflaechenleimungs- und/oder streichvorrichtung fuer eine papierbahn oder dergleichen
JPH03193157A (ja) * 1989-12-21 1991-08-22 Fuji Photo Film Co Ltd 塗布方法

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN vol. 015, no. 450 (C-0885), 15 November 1991 & JP 03 193157 A (FUJI PHOTO FILM CO LTD), 22 August 1991, *

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0823509A2 (de) * 1996-08-09 1998-02-11 Cartiere Burgo S.p.A. Papierbeschichtungsvorrichtung
EP0823509A3 (de) * 1996-08-09 1999-03-10 Cartiere Burgo S.p.A. Papierbeschichtungsvorrichtung
EP0911446A2 (de) * 1997-10-24 1999-04-28 Voith Sulzer Papiertechnik Patent GmbH Verfahren und Vorrichtung zur Beaufschlagung einer Papier- oder Kartonbahn mit einem flüssigen oder pastösen Auftragsmedium
EP0911446A3 (de) * 1997-10-24 2001-08-16 Voith Paper Patent GmbH Verfahren und Vorrichtung zur Beaufschlagung einer Papier- oder Kartonbahn mit einem flüssigen oder pastösen Auftragsmedium
DE19824804A1 (de) * 1998-06-03 1999-12-09 Voith Sulzer Papiertech Patent Verfahren und Vorrichtung zur Oberflächenbehandlung einer Papierbahn
EP1113108A2 (de) * 1999-12-24 2001-07-04 VITS-Maschinenbau GmbH Anlage zum Imprägnieren von durlaufenden Bahnen
DE19963151A1 (de) * 1999-12-24 2001-07-05 Vits Maschinenbau Gmbh Anlage zum Imprägnieren von durchlaufenden Bahnen
EP1113108A3 (de) * 1999-12-24 2002-09-11 VITS-Maschinenbau GmbH Anlage zum Imprägnieren von durlaufenden Bahnen
EP1607521A1 (de) * 2004-06-17 2005-12-21 Voith Paper Patent GmbH Auftragsvorrichtung
US7351289B2 (en) 2004-06-17 2008-04-01 Voith Paper Patent Gmbh Application device

Also Published As

Publication number Publication date
FI942688A0 (fi) 1994-06-07
FI96893C (fi) 1996-09-10
FI96893B (fi) 1996-05-31
FI942688A (fi) 1995-12-08
EP0687770A3 (de) 1997-05-21

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