FILM PRESS

Abstract: The invention concerns a method in a film press, in which the web(W) is coated or surface-sized from at least one side. In the film press (10) a film press nip (N) is formed between a first and a second film press roll (12, 16), and the coating agent or surface size is applied as a film (F1, F2) at least onto the face of the first film press roll (12). The web (W) is passed through the film press nip (N) so that in said nip (N) the coating agent or surface size is transferred from the face (12) of the film press roll onto the web (W). After the film press nip (N), the web (W') follows the face of the first film press roll (12), from which it is separated for a treatment of the coated or surface-sized web (W') following after the film press. According to the invention, the web (W') is separated in the desired geometry from the first film press roll (12) by means of a separation control device that has been fitted at the outlet side of the film press nip (N) at the opposite side of the web (W') in relation to the first film press roll, which separation control device is preferably a separation roll or cylinder (23).

Description: FILM PRESS 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. When a film transfer technique is employed, in film size presses, 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. As a rule, 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. At present, in paper machines and so also in the film size presses connected with them, ever higher speeds are aimed at, in which connection, in particular, the increase in this speed has brought a new problem, i.e. formation of coating-agent mist at the outlet side of the press nip especially when running with large quantities of coating agent. The formation of mist arises from splitting of the coating agent film in the film press when the web is separated from the film roll. Thus, in such a case, 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. Excessive formation of mist can, in itself, already be quite an important problem, which is noticed in inferior quality of the coating on coated paper. A problem also arises from the fact that even a smaller amount of mist is deposited on the constructions of the machine and drops onto the paper web and spoils the quality of the paper, or that the mist spreads into the air in the room. It is a second significant problem in film presses how to be able to control the line of separation of the web from the roll in the film press along which the web follows after the nip. In the prior- art solutions, 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. Since the problems described above have come out significantly with increased web speeds only, the prior art includes a very low number of solutions by whose means it might be possible to eliminate these problems or by whose means it might be at least possible to reduce these problems to a significant extent. In fact, there are some earlier solutions, and of these solutions it is possible to mention, for example, the FI Patent No. 90,266, in whose solution attempts have been made to prevent formation of mist by using a particular hood construction. In a corresponding way, in the FI Patent No. 93,243, a solution has been described in which formation of mist in itself is not prevented, but this mist is recovered by means of mechanical devices fitted at the outlet side of the nip, or attempts are at least made to recover the mist, in which case the mist should not have access to spread to other constructions. Thus, this earlier publication does not provide a solution for the mist formation itself either. Further, in the FI Patent No. 101,092, an improvement has been sought for the solutions in accordance with the patents mentioned above, and, thus, in the method described in this patent, action has been taken against the formation of coating agent mist itself so that, in the solution in accordance with the patent, in the coating process, attempts have been made to prevent formation of coating agent mist at the outlet side of the film press nip so that jets of steam are passed to the web side to be coated. With respect to the prior art, reference is made further to the US Patent 5,496,406, in which, in the film press, the web is supported after the nip by means of air support beams, which have been fitted so that a beam placed closer to the nip supports the web from the side of the roll which the web follows. 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. In view of achieving this objective, 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. On the other hand, 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. Most advantageously, in the method and the film press in accordance with the invention, a separation roll or a separation cylinder is used as a separation control device. 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. On the other hand, in the method and in the film press that makes use of the method, 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. Most advantageously, however, 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 most important advantages of the invention, as compared with the prior-art solutions, are therein that, in the invention, on one hand, attempts are made to keep the web supported as well as possible after the film press nip and, on the other hand, that in the present invention, in itself, attempts are not made to prevent spreading of mist alone, but, in stead, attempts are made to prevent formation of mist completely. When no mist is formed at all, consequently mist does not cause problems either. In the invention, 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. 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. The further advantages and characteristic features of the invention will come out from the following detailed description of the invention. In the following, the invention will be described by way of example with reference to the figures in the accompanying drawing. 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. Figures 3A, 3B and 3C illustrate further embodiments of the method and the size press in accordance with the invention. In Figs. 1 and 2 in the drawing, 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. On the other hand, 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. Between the loading arm 19 and the film press frame 11, 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. In the solutions shown in Figs. 1 and 2, 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. In the solutions of the invention illustrated in Figs. 1 and 2, when the web W runs through the film press nip N, the coating agent or size films F 1? F 2 are transferred from the faces of the rolls 12, 16 to the web W. After the film press nip N, the web W' coated from both sides follows the face of the first film press roll 12 a certain distance, from which face the web W' is then separated and passed to the treatment following after the film press 10, in particular to after-drying. In Figs. 1 and 2, these air drying devices are denoted with the reference numerals 30 and 31. In particular in the case of pigment coating, after the film size press, as a rule, such contact-free dryers are employed before a drying cylinder. The construction and the operation of the coating devices 15,21 are not described in detail in this connection, because they can be conventional, known from the prior art, and, consequently, do not constitute a part of the present invention. In prior-art solutions, attempts can also be made to pass the coated web W' directly out of the film press nip N by means of a long free draw to the air drying means 30,31 by means of an air turning device 32, in the way in which the run of the web is illustrated in the figures by means of dashed lines. This long free draw, however, involves the drawbacks that were described above. 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. In the solution in accordance with the invention, at the outlet side of the film press nip N, 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. Thus, 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. In reality, however, after the tangent point t, 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' . Thus, 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. In the cases of two-sided coating or surface sizing illustrated in Figs. 1 and 2, at the opposite side of the web W', i.e. at the side of the second film press roll 16, 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. In the embodiment shown in Fig. 2, 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. Thus, in this solution, 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. In the case of Fig. 2, as a suitable value of the linear load between the separation roll or cylinder 23 and the first film press roll 12 and the web W' placed on said roll, a linear load of 0...100 kN/m can be considered. Further, it is preferable that the linear load can be regulated. By means of a solution as shown in Fig. 2, in the separation of the web W' from the first film press roll 12, attempts are made to simulate the situation present at the side of the second film press roll 16, where, as was described above, no substantial formation of mist occurs. Further, it is preferable to place 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. In Figs. 1 and 2, it is shown further that, above the separation roll or cylinder 23, below the coating device 21 of the second film press roll 16, 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. By means of the shelf 29, 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. In 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' . By means of said loading arms 24 and loading cylinders 26, it is also possible to provide the possibility of regulation of the linear load mentioned above. The displaceability of the separation roll or cylinder 23 and the adjustability of its position can also be accomplished in some other way, different from that shown in Figs. 1 and 2. Since, in the case of two-sided coating, the web W' face placed against the separation roll or cylinder 23 has also been coated, care must be taken to prevent adhering of the coating to the face of the separation roll or cylinder 23. For this purpose, the face of the separation roll 23 can be made such that it repels the coating agent. When 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. In the case of 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. In such a case, in view of producing and/or intensifying the condensation effect, the separation roll or cylinder 23 can be cooled. Onto the face of the separation roll or cylinder 23, it is also possible to feed steam or a mixture of steam and air in order to secure a condensate film. Further, on the separation roll or cylinder, 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. The separation roll or cylinder 23 and its operation can be varied further depending on the properties that are desired from it. 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. Similarly, 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. In 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. 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 while complying with the shape of the air turning device. In this way, the separation line and/or the film splitting geometry can be brought very well under control. When the separation of the web takes place, for example, in the way shown in Fig. 1, in which case the film is torn along a line, the tear point can be stabilized and the wandering of the tear point brought under control. If 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. In the figures in the drawing, the run of the web W has been illustrated as taking place from the top obliquely towards the bottom, and it is shown that, after the nip N, the web W follows the first film press roll 12 placed below. For the geometry shown in the figures, there are, however, several alternative solutions, of which it is one alternative that, after the nip, the web W follows the upper, second film press roll 16. Also in such a case, the separation control device can be used as fitted at the opposite side of the web W. In the method and the film press in accordance with the invention, the web can also be guided so that it runs from the bottom upwards. When presented more generally, 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. Above, the invention has been described by way of example with reference to the preferred embodiments illustrated in the figures in the accompanying drawing. The invention is, however, not confined to the exemplifying embodiments shown in the figures alone, but different embodiments of the invention can show variation within the scope of the inventive idea defined in the accompanying patent claims.

Claims: Claims 1. A method in a film press, in which the web (W) is coated or surface-sized from at least one side so that in the film press (10) a film press nip (N) is formed between a first and a second film press roll (12,16), and the coating agent or surface size is applied as a film (F 1 ,F 2 ) at least onto the face of the first film press roll (12), the web (W) being passed through the film press nip (N) so that in said nip (N) the coating agent or surface size is transferred from the face of the film press roll (12) onto the web (W), in which connection, after the film press nip (N), the web (W) follows the face of the first film press roll (12), from which it is separated for a treatment of the coated or surface-sized web (W) following after the film press, characterized in that the web (W) is separated in the desired geometry from the first film press roll (12) by means of a separation control device (23,23A,23B,23C) that has been fitted at the outlet side of the film press nip (N) at the opposite side of the web (W) in relation to the first film press roll (12). 2. A method as claimed in claim 1, characterized in that a separation roll or cylinder (23,23A,23B) is used as the separation control device. 3. A method as claimed in claim 2, characterized in that, by means of the separation roll or cylinder (23,23A), a nip contact is formed with the film press roll (12) and with the web (W) placed on said roll so as to transfer the web from the first film press roll (12) onto the separation roll or cylinder (23, 23 A) under full support. 4. A method as claimed in claim 3, characterized in that the separation roll or cylinder (23) is loaded against the first film press roll (12) and against the web (W) placed on said roll with a linear load of 0...100 kN/m. 5. A method as claimed in claim 2, characterized in that the distance (L) from the face of the first film press roll (12) to the face of the separation roll or cylinder (23,23A,23B) is 0...1000 mm. 6. A method as claimed in claim 2, characterized in that the distance from the face of the first film press roll (12) to the face of the separation roll or cylinder (23,23A, 23B) is 0...600 mm. 7. A method as claimed in any of the claims 2 to 6, characterized in that, in a method in which the web (W) is coated or surface-sized from both sides, adhering of coating agent or surface size from a coating that has been formed on the face of the web (W) to the face of the separation roll or cylinder (23,23A,23B) is substantially prevented. 8. A method as claimed in claim 7, characterized in that, onto the face of the separation roll or cylinder (23), a water film is condensed to prevent adhering of coating agent or surface size onto said face. 9. A method as claimed in claim 7 or 8, characterized in that the separation roll or cylinder (23) is cooled in order to produce and/or to intensify the condensation effect. 10. A method as claimed in any of the claims 7 to 9, characterized in that steam or a mixture of steam and air is fed onto the face of the separation roll or cylinder (23) in order to secure a condensate film. 11. A method as claimed in any of the claims 2 to 10, characterized in that the separation roll or cylinder (23) is employed after the film press nip (N) as fitted in such a way that it substantially fills the opening nip (N) of the film press (10) in order to gather the mist produced by the film press nip on its face and further to transfer the mist onto the web (W). 12. A method as claimed in any of the claims 2 to 11, characterized in that the separation roll or cylinder (23) is allowed to revolve freely. 13. A method as claimed in any of the claims 2 to 11, characterized in that the separation roll or cylinder (23) is rotated at such a speed that the surface speed of the separation roll or cylinder corresponds to the speed of the web (W')- 14. A method as claimed in any of the claims 2 to 11, characterized in that the separation roll or cylinder (23) is rotated at such a speed that the surface speed of the separation roll or cylinder differs from the speed of the web (W). 15. A method as claimed in claim 1, characterized in that an air turning device (23 C) based on the coanda effect is used as the separation control device. 16. A method as claimed in claim 15, characterized in that the distance of the air turning device (23C) based on the coanda effect from the first film press roll (12) is 0...50 mm. 17. A method as claimed in claim 1, characterized in that an air turning device (23 C) based on direct blowing is used as the separation control device. 18. A method as claimed in any of the preceding claims, characterized in that the position and the distance of the separation control device (23,23A,23B,23C) from the face of the first film press roll (12) is varied and regulated during running in order to find an optimal web (W) separation point. 19. A film press, which has been arranged to coat or to surface-size the web (W) at least from one side, which film press (10) comprises a film press nip (N) formed by a first and a second film press roll (12,16), of which film press rolls at least the first roll (12) is provided with coating means (15,21) for application of a coating agent or surface size as a film (F l 5 F 2 ) onto the face of said film press roll (12), the web (W) being arranged to be passed through the film press nip (N) so that in said nip (N) the coating agent or surface size is transferred from the face of the film press roll (12) onto the web (W), in which connection, after the film press nip (N), the web (W) has been fitted to follow the face of the first film press roll (12), from which it has been arranged to be separated for a treatment of the coated or surface- sized web (W) that follows after the film press (10), characterized in that the film press (10) is provided with a separation control device (23,23A,23B,23C) which has been arranged at the outlet side of the film press nip (N) at the opposite side of the web (W) in relation to the first film press roll (12), and which device has been fitted to separate the web (W) from the first film press roll (12) in the desired geometry. 20. A film press as claimed in claim 19, characterized in that the separation control device is a separation roll or cylinder (23,23A,23B). 21. A film press as claimed in claim 20, characterized in that 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 so as to transfer the web from the first film press roll (12) onto the separation roll or cylinder (23) under full support. 22. A film press as claimed in claim 21, characterized in that the separation roll or cylinder (23) has been loaded against the first film press roll (12) and against the web (W) placed on said roll with a linear load of 0...100 kN/m. 23. A film press as claimed in claim 20, characterized in that the distance (L) from the face of the first film press roll (12) to the face of the separation roll or cylinder (23) is 0...1000 mm. 24. A film press as claimed in claim 20, characterized in that the distance (L) from the face of the first film press roll (12) to the face of the separation roll or cylinder (23) is 0...600 mm. 25. A film press as claimed in any of the claims 20 to 24, characterized in that, at least in a case in which the film press (10) is meant for two-sided coating or surface sizing of the web (W), adhering of coating agent of surface size from a coating that has been formed on the face of the web (W) to the face of the separation roll or cylinder (23) has been substantially prevented. 26. A film press as claimed in claim 25, characterized in that adhering of coating agent or surface size to the face of the separation roll or cylinder (23) has been prevented by means of a water film condensed onto the face of the separation roll or cylinder. 27. A film press as claimed in claim 25 or 26, characterized in that the separation roll or cylinder (23) can be cooled in order to produce and/or to intensify the condensation effect. 28. A film press as claimed in any of the claims 25 to 27, characterized in that, in order to secure a condensate film, steam or a mixture of steam and air has been arranged to be fed onto the face of the separation roll or cylinder (23). 29. A film press as claimed in any of the claims 25 to 28, characterized in that the face of the separation roll or cylinder (23) has been treated with a material that repels the coating agent or surface size used in the film press (10), for example with polytetrafluoroethylene. 30. A film press as claimed in any of the claims 20 to 29, characterized in that the separation roll or cylinder (23) is freely revolving. 31. A film press as claimed in any of the claims 20 to 29, characterized in that the separation roll or cylinder (23) is provided with a drive gear. 32. A film press as claimed in any of the claims 20 to 31, characterized in that the separation roll or cylinder (23) has been arranged to revolve at such a speed that the surface speed of the separation roll or cylinder corresponds to the web (W) speed. 33. A film press as claimed in any of the claims 20 to 31, characterized in that the separation roll or cylinder (23) has been arranged to revolve at such a speed that the surface speed of the separation roll or cylinder differs from the web (W) speed. 34. A film press as claimed in any of the claims 20 to 33, characterized in that the separation roll or cylinder (23) has been fitted at the outlet side of the film press nip (N) in such a way that it fills the opening nip (N) of the film press (10), in which connection said separation roll or cylinder has been fitted to gather the mist of coating agent or surface size produced by the film press nip (N) on its face and to transfer the mist further onto the web (W). 35. A film press as claimed in any of the claims 20 to 34, characterized in that the separation roll or cylinder (23 A) has been provided with a suction zone (23 A') so as to produce a hold on the web (W). 36. A film press as claimed in any of the claims 20 to 34, characterized in that the separation roll or cylinder is a blowing roll or cylinder (23B) for producing a contact-free transfer of the web (W). 37. A film press as claimed in claim 19, characterized in that the separation control device is an air turning device (23 C) based on the coanda effect. 38. A film press as claimed in claim 37, characterized in that the distance of the air turning device (23 C) based on the coanda effect from the first film press roll (12) is 0...50 mm. 39. A film press as claimed in claim 19, characterized in that the separation control device is an air turning device (23 C) based on direct blowing. 40. A film press as claimed in any of the claims 19 to 39, characterized in that the position and the distance of the separation control device (23,23A,23B,23C) from the face of the first film press roll (12) can be varied and regulated during running in order to find an optimal web (W) separation point.

Inventors: RANTANEN RAUNO, RANTANEN, RAUNO
Applicants: RANTANEN RAUNO, VALMET CORP, RANTANEN, RAUNO, VALMET CORPORATION
Application year: 1999
Main classification: D21H23
IPC codes: B05C1, B05C9, D21H23