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
  • D21H5/00—Special paper or cardboard not otherwise provided for
  • D21H5/0005—Processes or apparatus specially adapted for applying liquids or other fluent materials to finished paper or board, e.g. impregnating, coating
  • D21H5/0012—Processes or apparatus specially adapted for applying liquids or other fluent materials to finished paper or board, e.g. impregnating, coating by bringing paper into contact with an excess of fluids, the paper carrying away only a part of the fluid material, e.g. by passing through liquids, gases or vapours
• • 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
  • D21H23/32—Addition to the formed paper by contacting paper with an excess of material, e.g. from a reservoir or in a manner necessitating removal of applied excess material from the paper

Definitions

• Application rollers (DE-C 36 23 402) and application chambers open to the material web (EP-C 0 051 698) are known as application systems for the excess application.
• mechanical doctor elements such as doctor blades (DE-C 36 23 402), doctor rods (DE-C 30 22 955), doctor blades (EP-C 0 109 520) and so-called air knives are used as metering elements, which measure the excess with compressed air from a Strip off the slot nozzle (DE-A 40 14 463).
• the invention has for its object to improve a generic method and a generic device so that a coating with a uniform line pattern is achieved at very high web speeds.
• the invention is based on the knowledge that errors in the line diagram after scraping off the excess are due to irregularities in the excess film, which are no longer compensated for during metering.
• errors in the line diagram after scraping off the excess are due to irregularities in the excess film, which are no longer compensated for during metering.
• due to the convex ie. H.
• Towards the uncoated side curved web guide between applying and scraping off the excess considerable centrifugal forces on the coating material, which are directed away from the web.
• the centrifugal forces lead to the spraying off of coating material and / or to an irregularity, e.g. B. to form tension lines of the film reaching the dosing element
• the path is concave, that is curved towards the coated side.
• the centrifugal forces thus act in the direction of the web, so that not only the negative effects listed above are avoided, but even the film on the coating material is evened out by the centrifugal forces prior to metering.
• a further advantage is that the negative effects of air enclosed in the coating material or entrained by the web are reduced. Air in the coating material or on the web can lead to errors in the line drawing up to uncovered places on the end product.
• the centrifugal forces applied to the web force the air away from the web prior to metering, so that it escapes or at least is frequently found on the side of the excess film facing away from the web, which is then doctored off. The complete wetting of the web with coating material is guaranteed even with air inclusions.
• Figures 1 to 7 show the invention as a schematic diagram with different application and metering systems.
• FIG. 8 shows a concrete embodiment in a side view.
• All the coating devices shown in the figures have an application system 1 and a metering system 3 with a metering element arranged behind it in the running direction of the paper or cardboard web 2. Coating paint is applied in excess from the application system 1 as a coating material to the paper or cardboard web 2 and is then scraped off again by the metering element of the metering system 3 to the desired coat weight.
• Known application systems are used to apply the coating color: in the embodiments according to FIGS. 1, 2, 5, 6, 7 and 8, it is roller applicators with an applicator roller 6 that draws from an ink pan 4 and is driven with or in the opposite direction to the web 2 on this the excess film 7 applies.
• the embodiment according to FIG. 3 shows a so-called short dwell coater with a nozzle chamber 8 which is open towards the web 2 and to which the coating color is supplied in excess and with increased pressure.
• the application chamber 8 is on its outlet side from the metering element, for. B. a doctor knife 9, completed.
• metering systems 3 contain a scraper knife 9 as metering element.
• the scraper knife 9 is fastened with its foot in a clamping bar 11 which is mounted in a scraper bar 10 and can be moved back and forth to the track 2.
• the scraper knife 9 On its rear side facing away from the web 2, the scraper knife 9 is supported by a support bar 2, which is adjustably attached to the top of the scraper bar 10.
• a short dwell applicator with a doctor knife 9 is used in order to apply a predosed excess film 7 to the web 2.
• the final metering is carried out using a blade metering system, which also has a scraper knife 9 as the final metering element.
• the embodiment according to FIG. 5 contains a roller applicator 1 and a metering system 3 with an air knife as the metering element.
• the air knife consists of a slot nozzle 1 3 which extends over the width of the web 2 and is connected to a compressed air supply. Out the slot nozzle 1 3, a compressed air jet is directed against the excess film 7 in order to strip off the excess to the desired coat weight.
• An essential feature of the invention is the course of the web 2 between the application of the excess film 7 and the metering with the metering element 9 or 13 to the desired coating weight.
• the web 2 is curved so that the axis of curvature runs parallel to the web 2 and transverse to the web running direction on the coating side at a distance from it.
• the web 2 is preferably guided in a concavely curved manner over the entire distance between the application and metering (FIG. 1). In the case of concave guidance only on part of this section, the web 2 —as shown in FIG.
• the path 2 is preferably guided in a straight line when applying the excess and / or when metering. Following the concave path, the path 2 becomes straight or only slightly convex until dosing, i. e. curved towards the uncoated side, guided so that the positive effects of the concave web guide are not reversed, or only to a non-disturbing extent.
• a slight convex curvature can have the advantage that the material doctored off by the metering element 9 does not splash against the web 2. Since the concavely curved section compensates for unevenness in the excess film 7, it is possible under certain circumstances to place the web 2 in front of the concavely curved section, e.g. when applying the excess film 7, to be convexly curved without errors in the line diagram after dosing.
• FIGS. 6 and 7 show two options for realizing the concave path guidance:
• the paper or cardboard web 2 is guided around two guide rollers 14, 15 arranged parallel and at a distance from one another.
• the web 2 is curved concavely between the application system 1 and the metering system 3 by means of an air guide nozzle 16.
• Compressed air from the air guide nozzle 16 is coated against Side of the web 2 passed, the web tension is set so that the desired curvature is obtained.
• the outlet-side guide roller 1 5 also supports the web 2 during metering against the contact pressure of the doctor knife 9.
• the curvature of the web 2 can also be brought about with a vacuum on the uncoated side.
• FIG. 7 shows the principle of a preferred embodiment in which the coated and thus sensitive web 2 is supported on the uncoated side by a correspondingly curved guide surface during the concave guidance, preferably with an encircling support band 17.
• This is preferably made of an elastic one Support belt 17 made of material is likewise deflected by the two guide rollers 14, 15 deflecting the web 2.
• One or both guide rollers 14, 15, preferably only the inlet-side guide roller 14, are driven.
• the drive of only the guide roller 14 on the inlet side has the advantage that the strand 18 supporting the web 2 is under less tension and can therefore be curved more easily in a concave manner.
• the curvature of the strand 18 is caused by a vacuum between the two strands and / or by an overpressure acting from the outside against the coated side, e.g. in the manner described in the embodiment according to FIG.
• a circumferential support belt 17 can also be used concave curved mechanical guide surfaces against which the web 2, z. B. with compressed air.
• FIG. 8 The coating device shown in principle in FIG. 7 is shown in more detail in FIG. 8:
• the coating device has on both longitudinal sides of the web 2 frame parts 19, in which the two guide rollers 14, 15, designed as support rollers, the application system 1 and the metering system 3 are suspended at a distance from one another. Both support rollers 14, 15 are circulated by the endless support belt 17 made of an elastic material and extending over the working width of the device.
• the support belt 17 is driven at the web speed of the web 2 by the support roller 14, which is connected to a rotary drive, not shown.
• the application system 1 contains an application roller 6, which can be set against the support roller 14 in the area wrapped around the web 2.
• the applicator roller 6, which is preferably driven along with the counter roller 14, that is to say in the opposite direction of rotation, draws from an ink pan 5 and is mounted together with the latter on a pivoting lever 20 so that it can be raised and lowered.
• the dosing system 3 arranged in the web running direction at a distance behind the applicator in the area of the support roller 15 is described in principle in the explanation of FIG.
• the scraper bar 10 with the clamp bar 11 carrying the scraper knife 9 is pivotally suspended between two side parts 21 about the scraper knife tip.
• the side parts 21 themselves are pivotally mounted with the scraper bar 10, for. B. to be able to carry out a change of the doctor knife 9.
• the space 22 delimited by the circumference of the support rollers 14, 15 and the free run 18 of the support belt 17 is sealed and can be subjected to negative pressure in order to be able to set the desired concave curvature of the run 18 supporting the web 2.
• the coated side of the web 2 between the application roller 6 and the metering element 9 can be acted upon with compressed air.
• the space 23 between the applicator roller 6 and the metering element (doctor blade 9) is sealed with sealing elements with the exception of the side open to the web 2 and connected to a compressed air supply. The web 2 is thus pressed without contact against the guide surface formed by the strand 18.
• the web 2 When coating, the web 2 is first deflected by the inlet-side support roller 14, it lies on the outside of the support belt 17. Coating paint is applied in excess from the application roller 6 to the web 2, which is then, supported by the strand 1 8 of the support belt 17, guided in a concavely curved manner to the second support roller 1 5.
• the doctor blade 9 is arranged in the run-up area of the web 2 on the support roller 1 5, so that the support roller 1 5 the web 2 against the Pressure of the doctor blade tip is supported before it is continued so convexly by the support roller 15 that negative effects such as paint splashing, tension ring formation etc. occur.

Landscapes

• Coating Apparatus (AREA)
• Paper (AREA)
• Application Of Or Painting With Fluid Materials (AREA)
• Machines For Manufacturing Corrugated Board In Mechanical Paper-Making Processes (AREA)

Applications Claiming Priority (3)

Publications (2)

Family

ID=6526409

Family Applications (1)

Country Status (10)

Families Citing this family (6)

Family Cites Families (17)

• 1994
  • 1994-08-24 DE DE4429964A patent/DE4429964A1/de not_active Withdrawn
• 1995
  • 1995-06-24 AT AT95924322T patent/ATE169701T1/de not_active IP Right Cessation
  • 1995-06-24 JP JP8507719A patent/JP2818304B2/ja not_active Expired - Fee Related
  • 1995-06-24 WO PCT/EP1995/002464 patent/WO1996006226A1/fr active IP Right Grant
  • 1995-06-24 US US08/765,514 patent/US5869143A/en not_active Expired - Fee Related
  • 1995-06-24 KR KR1019970700463A patent/KR100197308B1/ko not_active Application Discontinuation
  • 1995-06-24 AU AU28878/95A patent/AU2887895A/en not_active Abandoned
  • 1995-06-24 EP EP95924322A patent/EP0777785B1/fr not_active Expired - Lifetime
  • 1995-06-24 CA CA002198264A patent/CA2198264A1/fr not_active Abandoned
  • 1995-06-24 DE DE59503187T patent/DE59503187D1/de not_active Expired - Fee Related
• 1997
  • 1997-02-21 FI FI970734A patent/FI107279B/fi active

Non-Patent Citations (1)

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