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
  • D21H23/52—Addition to the formed paper by contacting paper with a device carrying the material
  • D21H23/56—Rolls
• • 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
  • B05C1/00—Apparatus in which liquid or other fluent material is applied to the surface of the work by contact with a member carrying the liquid or other fluent material, e.g. a porous member loaded with a liquid to be applied as a coating
  • B05C1/04—Apparatus in which liquid or other fluent material is applied to the surface of the work by contact with a member carrying the liquid or other fluent material, e.g. a porous member loaded with a liquid to be applied as a coating for applying liquid or other fluent material to work of indefinite length
  • B05C1/08—Apparatus in which liquid or other fluent material is applied to the surface of the work by contact with a member carrying the liquid or other fluent material, e.g. a porous member loaded with a liquid to be applied as a coating for applying liquid or other fluent material to work of indefinite length using a roller or other rotating member which contacts the work along a generating line
  • B05C1/0826—Apparatus in which liquid or other fluent material is applied to the surface of the work by contact with a member carrying the liquid or other fluent material, e.g. a porous member loaded with a liquid to be applied as a coating for applying liquid or other fluent material to work of indefinite length using a roller or other rotating member which contacts the work along a generating line the work being a web or sheets
  • B05C1/083—Apparatus in which liquid or other fluent material is applied to the surface of the work by contact with a member carrying the liquid or other fluent material, e.g. a porous member loaded with a liquid to be applied as a coating for applying liquid or other fluent material to work of indefinite length using a roller or other rotating member which contacts the work along a generating line the work being a web or sheets being passed between the coating roller and one or more backing rollers
• • 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
  • B05C1/00—Apparatus in which liquid or other fluent material is applied to the surface of the work by contact with a member carrying the liquid or other fluent material, e.g. a porous member loaded with a liquid to be applied as a coating
  • B05C1/04—Apparatus in which liquid or other fluent material is applied to the surface of the work by contact with a member carrying the liquid or other fluent material, e.g. a porous member loaded with a liquid to be applied as a coating for applying liquid or other fluent material to work of indefinite length
  • B05C1/08—Apparatus in which liquid or other fluent material is applied to the surface of the work by contact with a member carrying the liquid or other fluent material, e.g. a porous member loaded with a liquid to be applied as a coating for applying liquid or other fluent material to work of indefinite length using a roller or other rotating member which contacts the work along a generating line
  • B05C1/12—Apparatus in which liquid or other fluent material is applied to the surface of the work by contact with a member carrying the liquid or other fluent material, e.g. a porous member loaded with a liquid to be applied as a coating for applying liquid or other fluent material to work of indefinite length using a roller or other rotating member which contacts the work along a generating line the work being fed round the roller
• • 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
  • B05C9/04—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 liquid or other fluent material to opposite sides of the work

Definitions

• the invention concerns a method in a film press, in which the web is coated or surface-sized from at least one side so that in the film press a film press nip is formed between a first and a second film press roll, and the coating agent or surface size is applied as a film at least onto the face of the first film press roll, the web being passed through the film press nip so that in said nip the coating agent or surface size is transferred from the film press roll onto the web, in which connection, after the film press nip, the web follows the face of the first film press roll, from which it is separated for a treatment of the coated or surface-sized web following after the film press.
• the invention also concerns a film press, which has been arranged to coat or to surface-size the web at least from one side, which film press comprises a film press nip formed by a first and a second film press roll, of which film press rolls at least the first roll is provided with coating means for application of a coating agent or surface size as a film onto the face of said film press roll, the web being arranged to be passed through the film press nip so that in said nip the coating agent or surface size is transferred from the face of the film press roll onto the web, in which connection, after the film press nip, the web has been fitted to follow the face of the first film press roll, from which it has been arranged to be separated for a treatment of the coated or surface-sized web that follows after the film press.
• the application of a size or of a paste onto a paper is carried out so that, depending on whether the paper is to be coated from one side only or from both sides, coating agent films of the desired thickness are applied, by means of applicator devices, onto the face/faces of one roll or both rolls in the film size press, in which connection these coating agent films are transferred onto the paper web in a nip formed by the size press rolls as the paper web runs through said nip.
• the film rolls in film size presses are provided with resilient coatings, and the application onto the roll face can be carried out by using some known blade coater, a bar coater provided with a smooth or grooved coating bar, or an equivalent nozzle equipment.
• mist arises from splitting of the coating agent film in the film press when the web is separated from the film roll.
• the coating agent film splits so that most of the film remains on the paper, whereas a smaller portion remains on the face of the film roll.
• the point of separation of the web from the roll does not remain the same, but the point of separation "wanders" along the roll face. Normally, when the point of separation has been followed by a long free draw, fluttering has occurred in the web, which may have resulted in web breaks and in their well-known detrimental consequences. Further, wandering of the web separation point in the machine direction and also in the cross direction causes a serious problem of mist formation.
• the object of the present invention is to provide a novel, improved solution for the control of the line of separation of the web as well as for the problems related to the formation of mist of coating agent or surface size and to spreading of the mist.
• the method in accordance with the invention is mainly characterized in that the web is separated in the desired geometry from the first film press roll by means of a separation control device which has been fitted at the outlet side of the film press nip at the opposite side of the web in relation to the first film press roll.
• the film press in accordance with the invention is mainly characterized in that the film press is provided with a separation control device which has been arranged at the outlet side of the film press nip at the opposite side of the web in relation to the first film press roll, and which device has been fitted to separate the web from the first film press roll in the desired geometry.
• a separation roll or a separation cylinder is used as a separation control device.
• a separation roll or cylinder By means of a separation roll or cylinder, it is possible to form nip contact with the first film press roll and the web placed on said roll so as to transfer the web from the first film press roll onto the separation roll or cylinder as fully supported.
• the separation roll or cylinder can be fitted at a distance from the first film press roll so that the distance from the face of the first film press roll to the face of the separation roll or cylinder is 0...1000 mm, favourably 0...600 mm.
• the separation roll or cylinder has been fitted in the film press displaceably so that its distance from the face of the first film press roll can be varied during running in order to find an optimal separation point of the web.
• the separation roll or cylinder is favourably placed at the outlet side of the film press nip so that the roll or cylinder fills the opening nip in the film press, in which case said separation roll or cylinder gathers the coating-agent or surface-size mist produced by the film press nip onto its face and transfers the mist further to the web. Further, it is important to prevent adhering of coating agent or surface size from the coating formed on the web face onto the face of the separation roll or cylinder.
• the web separation line is kept under control by supporting the web fully or by at least keeping the free draw very short, in which case splitting of the coating can be brought under control, and fluttering of the web and variation of the web separation line can be prevented.
• the web By means of air technology, in particular by means of an air turning device based on the coanda effect, the web can be separated from the roll in the desired geometry so that it follows the shape of the air turning device. In this way, the air separation line and/or the film splitting geometry are brought well under control. In this way, formation of mist can be substantially eliminated, and the runnability can be made good.
• Figures 1 and 2 are fully schematic side views of a film press in which the method in accordance with the present invention is used. Figs. 1 and 2 illustrate alternative embodiments of application of the method.
• FIGS 3A, 3B and 3C illustrate further embodiments of the method and the size press in accordance with the invention.
• the film press is denoted generally with the reference numeral 10.
• the film press 10 comprises a film press frame 11 mounted on a base C, on which frame the film press rolls 12, 16 have been mounted in a conven- tional way.
• the bearing housing 13 of the first film press roll i.e. of the lower roll, has been installed directly on the frame 11 of the film press and attached to the frame rigidly.
• the bearing housing 17 of the second film press roll i.e. of the upper roll, has been mounted on a loading arm 19, which has been linked by means of a pivot shaft fitted in the cross direction of the machine pivotally on the frame 11 of the film press.
• loading cylinders 22 have been fitted, by whose means the loading arm 19 is loaded so as to produce a nip pressure of the desired magnitude in the film press nip N formed by the lower roll 12 and by the upper roll 16.
• One of the film press rolls 12,16 favourably the upper roll 16, or, as an alternative, both film press rolls 12,16 can be variable-crown rolls so that the pressure in the nip N can be brought to the desired level in the cross direction of the machine.
• the film press 10 is meant for two-sided coating or surface sizing of the web W, and, thus, each film press roll 12,16 is provided with coating means 15,21, by whose means the size films or equivalent coating agent films F 1 ,F 2 are applied and smoothed onto the faces of said rolls 12,16.
• the invention can, however, also be applied to coating or surface sizing of the web W from one side only, in which case just one of the film press rolls 12, 16 must be provided with coating means 15,21. Further, in the case of coating or surface sizing from one side, in the arrangement as shown in Figs. 1 and 2, either one of the coating devices can be switched out of operation.
• the method in accordance with the present invention is based on a novel mode of separating the web W' from the face of the first film press roll 12, the web W' following the face of said roll after the film press nip.
• a separation roll or cylinder 23 has been fitted, which operates as the web W' separation control device and which has, in the solution of Fig. 1, been fitted at a distance L from the first film press roll 12.
• the distance L between the face of the film press roll 12 and the face of the separation roll 23 is favourably at the maximum 1000 mm, most appropriately 0...600 mm.
• the free draw of the web W' from the first film press roll 12 to the separation roll 23 remains short, in which case a controlled separation line and good runnability are obtained.
• the run of the coated web W' illustrated by a solid line, from the first film press roll 12 onto the separation roll 23, wherein the web W' is separated from the face of the film press roll 12 tangentially, is an optimal situation, which is aimed at by means of the solution shown in Fig. 1.
• the coated web W' follows the face of the film press roll 12 over a certain distance s, i.e. until the draw effect of the web W' surpasses the resistance to draw caused by the tear and splitting of the coating film between the web W' and the face of the film press roll 12. This is illustrated in Fig. 1 by a dashed-dotted line representing the run of the web W' .
• the web W' separation point oscillates and wanders between the tangent point t and the film tear point p shown in the figure.
• the tear point p of the coating film and the wandering of the tear point in the machine direction (and also in the cross direction) are, however, so well under control that the splitting of the film between the face of the film press roll 12 and the web W' does not cause substantial formation of mist.
• the film splits at a slower speed which can be characterized as a normal acceleration of an opening nip N.
• the splitting speed complies with the normal acceleration of web separation, in which case the separation speed is relatively low, and at this side of the web W' the formation of mist is quite little.
• the separation roll or cylinder 23 has been fitted in nip contact with the first film press roll 12 and with the web W' placed on said roll.
• the web W' is transferred from the first film press roll 12 onto the separation roll 23 under full support, in which case the point of separ- ation of the web W' from the first film press roll cannot "wander" at all, but it remains invariable and under full control.
• a linear load of 0...100 kN/m can be considered. Further, it is preferable that the linear load can be regulated.
• the separation roll or cylinder 23 at the outlet side of the film press nip N so that it fills the opening nip N in the film press 10, in which case the separation roll or cylinder 23 gathers, on its face, any mist of coating agent or surface size produced in the film press nip N, also from the side of the second film press roll 16. In such a case, the mist is transferred back onto the web W' from the face of the separation roll or cylinder 23.
• a shelf 29 may be placed to collect the mist and the coating agent or surface size that may drop from the coating device 21 and to prevent dropping of said agent onto the web W' and thereby spoiling the coating.
• a good space is provided for collecting any mist that may be formed, and in this connection it is possible to arrange, for example, suction devices (not shown) in order to collect and to discharge the mist.
• Figs. 1 and 2 in the drawing it is shown further that the separation roll or cylinder 23 has been mounted on the frame 11 of the film press by means of loading arms 24 pivotal around the shaft 25, which arms can be pivoted by means of loading cylinders 26, for example, between a situation as shown in Fig. 1, in which there is a distance L between the first film press roll 12 and the separation roll or cylinder 23, and a situation as shown in Fig. 2, in which the separation roll or cylinder 23 is in nip contact with the first film press roll 12 and with the web W' running on it. It is preferable that the distance L can be varied during running in order that an optimal point of separation could be found for the web W' .
• the face of the separation roll 23 can be made such that it repels the coating agent.
• the coating agent consists of surface size, a good result is obtained by making the face of the separation roll or cylinder 23 out of steel.
• a pigment coating as the face material it is possible to use, for example, polytetrafluoroethylene (Teflon ® ). In order to improve the non-adherence, it is further preferable to keep the face of the separation roll or cylinder 23 moist.
• Moisture can be produced, for example, by condensing a water film onto the face.
• the separation roll or cylinder 23 can be cooled.
• a water doctor can be employed.
• the separation roll or cylinder 23 can be provided with a drive gear, or it can be freely revolving.
• the speed of rotation (surface speed) can be equal to the speed of the web, but, on the other hand, the speed can also differ from the web speed.
• Fig. 3A is a schematic illustration of a solution in which the separation roll 23 A is a suction roll, which is provided with a suction zone 23 A'. By means of the suction zone 23 A', the desired hold is provided and applied to the web W' on the desired distance or within the desired sector.
• Fig. 3B it is shown in Fig. 3B that, as the separation roll or cylinder, it is possible to employ a blowing roll 23B. Such a solution is favourable when it is desirable to provide a contact-free transfer of the web W' over the separation roll 23B.
• FIG. 3C it is shown that, further, as constructions substituted for a separation roll or cylinder 23, it is possible to employ an air turning device 23C.
• the air turning device 23 C can be, for example, an air turning device based on the coanda effect.
• the distance of such an air turning device from the film press roll 12 is favourably in a range of 0...50 mm.
• the air turning device 23C can also be an air turning device based in direct blowing, which is likewise fitted at an adjustable distance of 0...50 mm from the film press roll.
• the separation geometry of the air turning device can be linear, concave or convex.
• the tear point can be stabilized and the wandering of the tear point brought under control.
• the separation takes place, for example, in the way shown in Fig. 2, in which the situation present in the film press nip at the opposite side of the web is simulated, attempts are made to minimize the speed of splitting of the film, i.e. the film is given time to split.
• the web W follows the first film press roll 12 placed below.
• the separation control device can be used as fitted at the opposite side of the web W.
• the web can also be guided so that it runs from the bottom upwards.
• the rolls that form the nip in the film press can be fitted in any geometry whatsoever, and in two-sided coating or surface sizing, the web separation control device can be at any side of the web whatsoever, depending on which of the rolls in the film press the web is made to follow after the nip.

Landscapes

• Application Of Or Painting With Fluid Materials (AREA)
• Wire Bonding (AREA)
• Casting Or Compression Moulding Of Plastics Or The Like (AREA)
• Encapsulation Of And Coatings For Semiconductor Or Solid State Devices (AREA)
• Adhesive Tapes (AREA)

Priority Applications (4)

Applications Claiming Priority (2)

Publications (1)

Family

ID=8552054

Family Applications (1)

Country Status (6)

Cited By (3)

Citations (3)

• 1998
  • 1998-06-23 FI FI981445A patent/FI111020B/fi not_active IP Right Cessation
• 1999
  • 1999-06-22 DE DE69915292T patent/DE69915292T2/de not_active Expired - Lifetime
  • 1999-06-22 EP EP99931319A patent/EP1092062B1/en not_active Expired - Lifetime
  • 1999-06-22 AU AU47870/99A patent/AU4787099A/en not_active Abandoned
  • 1999-06-22 WO PCT/FI1999/000547 patent/WO1999067467A1/en active IP Right Grant
  • 1999-06-22 AT AT99931319T patent/ATE261021T1/de active

Patent Citations (4)

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