EP1319747A2 - Verfahren und Vorrichtung zum Vorhangbeschichten - Google Patents

Verfahren und Vorrichtung zum Vorhangbeschichten Download PDF

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Publication number
EP1319747A2
EP1319747A2 EP20020258619 EP02258619A EP1319747A2 EP 1319747 A2 EP1319747 A2 EP 1319747A2 EP 20020258619 EP20020258619 EP 20020258619 EP 02258619 A EP02258619 A EP 02258619A EP 1319747 A2 EP1319747 A2 EP 1319747A2
Authority
EP
European Patent Office
Prior art keywords
curtain
coating
substrate
collecting pan
starting
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Withdrawn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
EP20020258619
Other languages
English (en)
French (fr)
Inventor
Markus Gueggi
Robert Urscheler
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.)
Dow Global Technologies LLC
Original Assignee
Dow Global Technologies LLC
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 Dow Global Technologies LLC filed Critical Dow Global Technologies LLC
Publication of EP1319747A2 publication Critical patent/EP1319747A2/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Withdrawn legal-status Critical Current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
    • D21H23/00—Processes or apparatus for adding material to the pulp or to the paper
    • D21H23/02—Processes or apparatus for adding material to the pulp or to the paper characterised by the manner in which substances are added
    • D21H23/22—Addition to the formed paper
    • D21H23/46—Pouring or allowing the fluid to flow in a continuous stream on to the surface, the entire stream being carried away by the paper
    • D21H23/48—Curtain coaters
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05C—APPARATUS FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05C5/00—Apparatus in which liquid or other fluent material is projected, poured or allowed to flow on to the surface of the work
    • B05C5/007—Slide-hopper coaters, i.e. apparatus in which the liquid or other fluent material flows freely on an inclined surface before contacting the work
    • B05C5/008—Slide-hopper curtain coaters
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05C—APPARATUS FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05C9/00—Apparatus or plant for applying liquid or other fluent material to surfaces by means not covered by any preceding group, or in which the means of applying the liquid or other fluent material is not important
    • B05C9/06—Apparatus or plant for applying liquid or other fluent material to surfaces by means not covered by any preceding group, or in which the means of applying the liquid or other fluent material is not important for applying two different liquids or other fluent materials, or the same liquid or other fluent material twice, to the same side of the work

Definitions

  • curtain coating methods and apparatus are widely known and used.
  • a continuous web or sheets are continuously moved below a coating hopper.
  • One or more liquid compositions are provided from a hopper arrangement in the form of a liquid curtain.
  • liquid compositions are used of relatively low viscosity, generally less than about 150 cP (centipoise), most in the range from about 5 to about 100 cP.
  • one of the most often addressed problems for coating is the starting and stopping of the coating process without contaminating the substrate or coating apparatus due to spattering of the applied liquid, destroying of the substrate due to wrinkling and causing interference because of moving air during preparation of the curtain and unevenness of coating on the substrate. Moving air may also cause contamination of the substrate and the apparatus.
  • the coating point which designates the location where the coating liquid first contacts the substrate.
  • this location has the form of a line across the substrate and is referred to as the dynamic wetting line.
  • the area near the substrate where the air is in motion due to friction is called the boundary layer.
  • an application start plate positioned so as to prevent the curtain from reaching the web or a substrate for the thin curtain of the liquid beginning to be applied to the moving web.
  • the application start plate is curved or bent such that it surrounds a backup roller, the lower end of the plate being pivotally coupled to a fulcrum under the nearby backup roller.
  • the application start plate is pivoted downward about the fulcrum so that the upper end of the plate is moved away from the first position into a second position such that the curtain is allowed to reach the moving web.
  • the apparatus also provides a slide hopper which may be moved toward the backup roller while the application start plate remains in a prescribed first position so that the curtain falls in front of the upper end of the application start plate and reaches the moving web.
  • the application plate may be flat having an upper end extending at an oblique angle to the direction of width of the thin curtain of liquid.
  • the oblique angle of the upper end of the plate relative to the direction of width of the curtain is 1 degree to 30 degrees, especially 2 degrees to 10 degrees.
  • the application start plate is bent in an L-shape to have a curtain receiving part at the upper end of the plate, the application plate being turnable so that the upper end thereof is moved away from a first position so as to prevent the curtain from reaching the web into a second position so as to allow the curtain to reach the web.
  • the application start plate may not only be turnable but also slidable, pivotably coupled to a fulcrum under a nearby backup roller or a curved or bent or L-shaped plate.
  • a coating method and apparatus wherein before and at the start of coating an air shielding device is kept far from an impingement position where a free-falling curtain impinges onto the web. Just after starting of the coating process the air shielding device is moved close to the impingement position which prevents the air shielding device from being contaminated with splashes of coating liquids.
  • the apparatus comprises a movement mechanism moving the coating head horizontally so as to move it to or from a backup roller.
  • a curtain deflector is arranged in a space between a coating head and the backup roller, such that during preparation of coating the coating head may be placed far from the backup roller and the curtain deflector receives coating liquid curtain free falling from the coating head to guide it into a preparation pan until the free-falling curtain stabilizes.
  • the curtain deflector according to this document is flat and bent and the preparation pan is provided under the curtain deflector and coating head.
  • a curtain application device comprises an application starting plate which is a rectangular flat plate positioned such that the curtain is prevented from reaching the web. Firstly, the liquid flows down to the application start plate and is gathered into a recovery vessel. The application start plate is then turned about a fulcrum so that the liquid curtain is allowed to reach the web, thus, starting the application of the liquid curtain to the web.
  • the device provides the problem that a large space for turning or sliding the application start plate needs to be provided in the device. The large space needs to be provided so as to make it possible to move the slide hopper over the path of the moving web and to make the height of the curtain sufficient.
  • curtain deflectors or application start plates have to be turned or slid or pivoted next to a nearby backup roller such that there is a risk of disturbing or interfering the movement of the backup roller.
  • a method and apparatus for starting and stopping the curtain coating process of a moving substrate like a paper web, wherein a substrate is moved below a hopper arrangement providing one or more liquid coating materials in the form of a free-falling curtain impinging the substrate at a dynamic wetting line, wherein a movable collecting pan is provided as well as a movable hopper arrangement.
  • a baffle means is provided to build a discharging channel for the boundary layer or film during preparation of the curtain.
  • the method of starting the coating process comprises the steps of starting the apparatus and movement of the substrate providing an increased distance to a wiper or baffle means, preparing the curtain by pouring coating material from the hopper arrangement into a movable collecting pan, moving the hopper arrangement and curtain into a pre-coating position, preferably near the baffle means while still pouring coating material into the collecting pan, bringing the hopper arrangement and baffle means into the coating position and rapidly moving the collecting pan away from baffle means and the substrate to be coated.
  • the hopper arrangement is in a preparation position during the starting step of the curtain coating method.
  • the coating process is started by retracting the collecting pan as rapidly as possible to provide an even coating thickness over the width of the substrate.
  • the collecting pan builds a discharging channel for the boundary layer during curtain preparation such that there is no risk of air motion during curtain preparation.
  • the hopper arrangement preferably positioned in pre-coating position during starting of the apparatus, prevents contamination of the substrate and the apparatus during starting and stopping of coating process.
  • the coating process can be stopped by reversing the performing order of the steps used to start the process.
  • the hopper arrangement and collecting pan are movable and there is not provided an application start plate which may cause the coating liquid to spatter leading to contamination of the apparatus and substrate.
  • the collecting pan is moved rapidly into the curtain such that the coating process stops with a definite line on the substrate.
  • the hopper arrangement is moved to pour curtain into the collecting pan.
  • the baffle, or especially wiper means is lifted from the surface of the substrate in order to avoid wrinkling of the substrate which could lead to its scratching or breaking.
  • means to horizontally move the hopper arrangement and collecting pan are provided as well as means to vertically move the baffle or wiper means.
  • FIG. 1 shows an apparatus for curtain coating as known from the prior art.
  • Such conventional curtain coating apparatus has means, preferably in form of a backing roller 10 for forwarding separate sheets or continuous web 12 as a substrate to be coated.
  • the web 12, which may comprise a paper is forwarded along the backing roller 10 through the curtain coater.
  • a hopper arrangement 14 is located generally above the backing roller 10.
  • Various forms of hopper arrangements 14 are known, generally providing a curtain 16 of a coating liquid free falling over a distance forwarded over a lid 18 or any other suitable means.
  • the coating curtain 16 is moved towards the substrate 12 on the backing roller by gravity force and impinged on the substrate generally perpendicular to the moving direction of the substrate.
  • curtain deflector 20 as well as a collecting pan 22.
  • the hopper arrangement 14 as well as the curtain deflector 20 are movable in two directions. Also the direction of movement of the substrate on the backing roller is illustrated.
  • curtain 16 is poured onto the curtain deflector 20.
  • the free-falling curtain is guided into the collecting pan which is provided under the movable curtain deflector.
  • the hopper arrangement Before the preparation of coating the hopper arrangement is positioned far from the backing roller and the curtain deflector is moved to the space between the curtain head and the backing roller.
  • the adaptation of moving hopper arrangement and curtain deflector is relatively difficult and there is still the risk of contamination of the substrate and the apparatus because of the coating liquid falling on the deflector spattering onto the substrate and apparatus.
  • a curtain deviator is not provided anymore.
  • FIGS 2 to 5 show steps of the method and an apparatus according to the present invention. Parts being the same or similar to those described above are depicted by the same reference numbers for the ease of understanding.
  • the apparatus comprises the hopper arrangement 14 pouring the curtain 16 over lid 18 into a collecting pan 24.
  • the moving substrate 12 is positioned next to the collecting pan according to figure 2.
  • a baffle means 26 is also provided in a raised position illustrated by arrow 28.
  • Figure 2 shows the curtain preparation step where the collecting pan is positioned next to the baffle means 26 and where the curtain 16 is poured into the deeper portion of the collecting pan.
  • the coating pan is formed to be adapted to the form of the substrate moving means, i. e. it is wedge-shaped having a relatively deep portion where the curtain can be poured into during the first preparation step.
  • the other end of the collecting pan directed to the baffle means 26 is tapered in order not to intersect with the moving substrate.
  • the hopper arrangement 14 is moved horizontally towards the baffle means 26 still pouring curtain 16. The movement is illustrated by an arrow.
  • the baffle means 26 is still in the lifted position to avoid wrinkling or scratching of the substrate.
  • Coating liquid 30 runs over the bottom surface 32 of the collecting pan. The poured coating material is still collected in the collecting pan in its deeper portion.
  • a fourth step shown in figure 4 the curtain 16 and the baffle means 26 are brought in coating position.
  • the lowering step is marked with arrow 36.
  • the collecting pan is positioned such that curtain 16 is still poured into the tapered portion of collecting pan. Coating liquid still runs over the bottom surface 32 of collecting pan 24 to be collected at the deeper portion of the collecting pan.
  • the coating process is not yet started but the substrate is preferably accelerated to the optimal speed to be coated.
  • Stopping of the coating process may be carried out similar to the starting of coating process, preferably by reversing the above steps.
  • the process of starting the apparatus and the coating process is much easier than with an apparatus of the prior art as illustrated in figure 1.
  • the apparatus according to the invention provides excellent operating behavior without the necessity of complicated and sophisticated deviator means and is therefore much easier to use, and not only assumed to be more reliable compared to the prior art but also much more cost effective.

Landscapes

  • Application Of Or Painting With Fluid Materials (AREA)
  • Coating Apparatus (AREA)
EP20020258619 2001-12-13 2002-12-13 Verfahren und Vorrichtung zum Vorhangbeschichten Withdrawn EP1319747A2 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US34116901P 2001-12-13 2001-12-13
US341169P 2001-12-13

Publications (1)

Publication Number Publication Date
EP1319747A2 true EP1319747A2 (de) 2003-06-18

Family

ID=23336500

Family Applications (1)

Application Number Title Priority Date Filing Date
EP20020258619 Withdrawn EP1319747A2 (de) 2001-12-13 2002-12-13 Verfahren und Vorrichtung zum Vorhangbeschichten

Country Status (1)

Country Link
EP (1) EP1319747A2 (de)

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2005033406A1 (de) * 2003-09-30 2005-04-14 Voith Paper Patent Gmbh Auffangwanne
WO2005059250A1 (de) * 2003-12-17 2005-06-30 Voith Paper Patent Gmbh Vorhangauftragswerk
EP1596004A1 (de) * 2004-05-13 2005-11-16 Voith Paper Patent GmbH Vorhangs-Auftragsvorrichtung
WO2006008336A1 (en) * 2004-07-20 2006-01-26 Metso Paper, Inc. Curtain coater unit and curtain coating method
WO2006031538A1 (en) * 2004-09-09 2006-03-23 Avery Dennison Corporation Curtain coating method
EP1525924A3 (de) * 2003-10-22 2008-01-23 Voith Patent GmbH Maschine zum Auftragen eines flüssigen oder pastösen Auftragmediums auf die Oberfläche einer laufenden Materialbahn
WO2009000715A1 (de) * 2007-06-26 2008-12-31 Voith Patent Gmbh Auftragsverfahren sowie vorhangauftragswerk
US7473333B2 (en) * 2002-04-12 2009-01-06 Dow Global Technologies Inc. Process for making coated paper or paperboard
EP1749585A3 (de) * 2005-08-04 2009-07-22 Voith Patent GmbH Auftragsverfahren
US7909962B2 (en) 2001-04-14 2011-03-22 Dow Global Technologies Llc Process for making multilayer coated paper or paperboard
CN102039253A (zh) * 2009-10-09 2011-05-04 安德里茨库斯特斯有限责任公司 帘幕式涂布机

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7909962B2 (en) 2001-04-14 2011-03-22 Dow Global Technologies Llc Process for making multilayer coated paper or paperboard
US7473333B2 (en) * 2002-04-12 2009-01-06 Dow Global Technologies Inc. Process for making coated paper or paperboard
WO2005033406A1 (de) * 2003-09-30 2005-04-14 Voith Paper Patent Gmbh Auffangwanne
EP1525924A3 (de) * 2003-10-22 2008-01-23 Voith Patent GmbH Maschine zum Auftragen eines flüssigen oder pastösen Auftragmediums auf die Oberfläche einer laufenden Materialbahn
WO2005059250A1 (de) * 2003-12-17 2005-06-30 Voith Paper Patent Gmbh Vorhangauftragswerk
EP1596004A1 (de) * 2004-05-13 2005-11-16 Voith Paper Patent GmbH Vorhangs-Auftragsvorrichtung
WO2006008336A1 (en) * 2004-07-20 2006-01-26 Metso Paper, Inc. Curtain coater unit and curtain coating method
CN101014418B (zh) * 2004-09-09 2010-09-01 艾利丹尼森公司 帘式涂布方法
AU2005285221B2 (en) * 2004-09-09 2010-11-11 Avery Dennison Corporation Curtain coating method
WO2006031538A1 (en) * 2004-09-09 2006-03-23 Avery Dennison Corporation Curtain coating method
EP1749585A3 (de) * 2005-08-04 2009-07-22 Voith Patent GmbH Auftragsverfahren
WO2009000715A1 (de) * 2007-06-26 2008-12-31 Voith Patent Gmbh Auftragsverfahren sowie vorhangauftragswerk
CN102039253A (zh) * 2009-10-09 2011-05-04 安德里茨库斯特斯有限责任公司 帘幕式涂布机

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