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

Definitions

• the present invention relates to a curtain coater unit of a paper/board machine for coating a material web, the curtain coater unit comprising a frame element located above the material web, a curtain coater connected to the frame element, from which curtain coater the coating agent can be fed as a curtain-like stream onto the surface of the material web at an impact point, and boundary-layer air exhaust means.
• curtain coater unit used in a paper/board machine and its operation
• the curtain coater unit is comprised of an elongated nozzle beam fitted transversely with respect to the direction of travel of the material web to be coated, above the material web and on the support frame.
• the coating agent is applied through the wide nozzle part of the nozzle beam, or a corresponding feeder part, such as an inclined plane, as a curtain-like stream onto the surface of the material web moving below the nozzle, to an impact point (a point in the web onto which the curtain drips).
• an impact point a point in the web onto which the curtain drips.
• boundary-layer air exhaust means that are separate from the nozzle part.
• the means include a suction surface fitted so as to face the surface of the material web to be coated, through which suction surface the layer of air on the surface of the material web is sucked into the exhaust ducts, and an air doctor between the suction surface and the impact point.
• the problem with this type of a curtain coater unit relates to controlling the support frame, and thus the straightness of the nozzle beam, in the changing loading environment. Even the slightest deflection of the nozzle unit will affect the size of the nozzle slot and thus the feed rates of the coating agent to be fed.
• these problems are solved by manufacturing sufficiently rigid nozzle beams. Such structures are large, difficult to manufacture and thus also expensive to manufacture.
• the external mechanical loads are generally essentially constant, the relatively instable thermal load in the surroundings of the nozzle part and the actual thermal expansion of the nozzle part and air currents bring additional problems to controlling straightness and thus also the amounts of the coating agent to be fed. Temperature variations are caused by heat brought along by the material web to the curtain coater unit area.
• the calibration room is a large space or room where the prevailing ambient conditions are maintained suitable for coating, especially as concerns the support frame and the nozzle beam. This type of solution takes up much space and is expensive.
• the aim of the present invention is to provide a curtain coater unit by means of which some of the above-mentioned disadvantages are eliminated or can be substantially reduced.
• the present invention is characterised in that the boundary-layer air exhaust means are connected with the frame element, and that at least a part of the frame element is fitted between the material web and the nozzle beam of the curtain coater.
• the effects (temperature changes and air currents) of external loads and other factors disadvantageous to the application of the coating agent, that otherwise directly affect the curtain coater or the coating agent curtain being applied, are partly or completely avoided.
• the structure of the unit can be fitted into a smaller, more compact space, whereby also the desired height of the coating agent curtain is easier to achieve.
• Figure 1 shows a cross-section of a curtain coater unit according to the invention
• Figure 2 shows another embodiment of the curtain coater unit according to the present invention.
• FIG. 1 thus shows a curtain coater unit according to the invention, which is marked by reference numeral 1.
• the curtain coater unit 1 is located essentially above a material web W travelling on its track.
• the curtain coater unit 1 comprises a curtain coater 4, or application beam.
• the coating agent is formed into a curtain 20 of equal width with the material web W, which is applied from a predetermined height onto the surface of the moving material web W at the impact point 21.
• the application beam 4 is arranged in the frame element 2 of the curtain coater unit 1, for example, by means of a support belonging in conjunction with the frame element 2.
• the frame element 2 is elongated in the lateral direction of the material web W.
• the cross-section of the frame element 2 is preferably C-shaped, which means that it is open on one side and its curved walls limit the space 10. The shape of the cross-section, therefore, makes it possible to fit the application beam at least partly through the open side into the space 10.
• the frame element 2 remains partly between the lower material web W and the application beam 4.
• the frame element 2 itself thus forms an application beam 4 cover which prevents substantially the passage of harmful air currents and heat carried with the web W onto the application beam 4.
• the application beam 4 is located in the space 10 in such a way that its nozzle part is outside the space 10, which means that through it the coating agent 20 can be applied past the wall formed by the space 10 and further to the impact point 21 of the material web W moving below.
• the material used for the frame element 2 is usually steel.
• the frame element 2 may also be coated or covered by any thermally insulating material to improve thermal insulation.
• boundary-layer air A exhaust means 5, 3, which are preferably located at a point before the impact point 21 with respect to the direction of travel of the material web W.
• the boundary-layer air A is a layer of air formed on the surface of the material web W, which moves with the travelling material web W.
• the boundary-layer air A exhaust means include a suction box 5 or the like, in which is formed a suction surface facing the material web W. On the suction surface are made, for example, openings, through which the boundary-layer air moves from the surface of the material web W to the suction box 5.
• the suction box is further in contact with the suction duct 3, through which the boundary-layer air A is removed from the material web W and from the impact point 21 area.
• the suction duct is arranged in connection with the outer surface of the frame element 2 wall, that is, on the opposite side of the wall with respect to the application beam 4.
• the suction duct 3 is preferably formed of the curved wall of the frame element 2 and a curved duct element 30 arranged at a distance from the outer surface of the wall, the said element essentially surrounding the outer surface of the frame element 2.
• the suction duct is thus formed in the space remaining between the frame element 2 and the duct element.
• an elongated doctor blade means 5b in connection with the suction box 5, in front of the impact point 21, is preferably arranged an elongated doctor blade means 5b, which is located transversely to the direction of travel of the material web W.
• the boundary-layer air A can be removed from the surface of the material web W in a controlled manner.
• the air A flowing in the suction duct 3 and the duct element for its part both insulate and carry away heat otherwise conveyed from the material web W to the frame element 2 and further to the application beam 4.
• the suction duct 3 is made so long that the air A flowing in it will even out possible transverse temperature differences in the material web W.
• the heat possibly conveyed to the frame element 2 and application beam 4 is as uniform as possible in the transverse direction of the frame element 2 and the application beam 4.
• the application beam 4 and the boundary-layer air A exhaust means 5, 3 are located, in accordance with the invention, in the same protective frame structure, whereby a compact structure is obtained where the equipment effecting the different functions can be placed in their optimal locations.
• the desired height of the coating agent curtain 20 is easier to obtain.
• Figure 2 shows diagrammatically another preferred embodiment of the invention.
• the curtain coater unit 1 is comprised of a frame element 2 according to the first embodiment which is located partly between the material web W and the application beam 4, and in the space 10 formed by the walls of which the application beam 4 is at least partly located.
• suction duct 3 also other means intended for handling air are arranged conjunction with the frame element 2, the structure and operation of the said means being described in greater detail below.
• the behaviour of the coating agent curtain 20 in the impact point 21 area is controlled by means of stabilisation air C, which is supplied to the impact point 21 area through blasting means 7, 7a, 7b and removed from the impact point 21 area through exhaust means 6, 6a, 6b.
• the stabilisation air C blasting means comprise a blasting duct 7a through which the stabilisation air C is conveyed to the curtain coater unit 1. From the blasting duct 7a the stabilisation air C is fed to a distributing duct 7.
• the distributing duct 7 is formed in the space remaining between the inner surface (the surface on the application beam 4 side) of the curved wall of the frame element 2 and the curved duct element 70 arranged at a distance from the inner surface.
• One end of the distributing duct 7 forms the nozzle part 7b of the stabilisation air C blowing means, which is fitted to guide the stabilisation air at an appropriate force in the impact point 21 area, over the entire width of the coating agent curtain 20.
• the stabilisation air C is thus removed by the exhaust means 6, 6a, 6b, including suction duct 6b which is fitted in the immediate vicinity of the nozzle part 7b, in front of the impact point 21.
• a transfer duct 6 As an extension of the suction duct 6b is arranged a transfer duct 6.
• the transfer duct 6 is made in compliance with the transfer duct 3 described in connection with the first embodiment.
• the transfer duct 6 is formed in the space between the outer surface of the frame element 2 and a second duct element 60 arranged at a distance from the frame element 2.
• the actual exhaust duct 6a transverse to the web, through which the stabilisation air C is removed from the curtain coater unit 1.
• the exhaust duct 6a is also located as far as possible from the material web W, however as close to the frame element 2 as possible, whereby the structure of the curtain coater unit 1 will remain compact.
• boundary-layer air A exhaust means 5, 3, 3a and support air B blasting means 8, 8a, 8b in connection with the frame element 2.
• the boundary-layer air A exhaust means include a suction box 5 or the like, which is fitted in the immediate vicinity of the suction duct 6b, in front of the suction duct 6b in the direction of travel of the material web W.
• a boundary-layer air A transfer duct 3 As an extension of the suction box 5 is arranged a boundary-layer air A transfer duct 3.
• the transfer duct 3 is formed in the space remaining between the second duct element 60 arranged at a distance from the frame element 2 and the third duct element 30.
• the third duct element 30' thus also forms the outermost surface or cover of the curtain coater unit 1, which for its part insulates the nozzle beam 4 from the heat released by the material web.
• the actual exhaust duct 3a transverse to the track, through which the boundary-layer air A is removed from the curtain coater unit 1.
• support air B blasting means 8, 8a, 8b In conjunction with the boundary-layer air A exhaust means 5, 3, 3a are further fitted support air B blasting means 8, 8a, 8b, by means of which the air B supporting material web W is blasted under low pressure onto the surface of the material web W. Typically, the blast pressure is 5 to 10 pascals, but it may deviate from this.
• the support air B blasting means 8, 8a, 8b include the blasting duct 8a, through which the support air B is conveyed to the curtain coater unit 1. In this case, the blasting duct 8a is located adjacent to the boundary-layer air A exhaust duct 3a, in the suction duct 3 limited by the second duct element 60 and the third duct element 30'.
• a distributing duct 8 into which the support air B from the blasting duct 8a is fed.
• the duct elements 60 and 30' are arranged at such a distance from one another that it has been possible to locate the distributing duct 8 in the transfer duct 3 limited by the duct elements 60 and 30'.
• the distributing duct 8 is the duct 8 remaining between the elements 80 shown in broken line, whereby the suction duct 3 essentially surrounds it.
• the end of the distributing duct 8 forms the nozzle part 8b which is preferably fitted in connection with the suction box 5, in the vicinity of the material web W. Through the nozzle part 8b the support air B is guided over the total width of the material web W surface.

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• Coating Apparatus (AREA)
• Paper (AREA)
• Application Of Or Painting With Fluid Materials (AREA)

Priority Applications (2)

Applications Claiming Priority (2)

Publications (1)

Family

ID=8566441

Family Applications (1)

Country Status (5)

Cited By (2)

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Citations (3)

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• 2003
  • 2003-06-26 FI FI20035108A patent/FI115407B/fi not_active IP Right Cessation
• 2004
  • 2004-05-24 CN CNB2004800151241A patent/CN100390355C/zh not_active Expired - Fee Related
  • 2004-05-24 WO PCT/FI2004/050076 patent/WO2004113615A1/en active Application Filing
  • 2004-05-24 DE DE112004001099T patent/DE112004001099B4/de not_active Expired - Fee Related
  • 2004-05-24 JP JP2006516240A patent/JP4429312B2/ja not_active Expired - Fee Related

Patent Citations (3)

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