SE465112B - DEVICE FOR CONTINUOUS APPLICATION OF A SINGLE COATING ON A MATERIAL COAT - Google Patents

Description

465 112 cause the material web to become uncoated in spots. P g a _den smala the gap still rises the hydrodynamic pressure disproportionately so that the rather positive effect of the partial dewatering becomes a disadvantage, insofar as the coating material can pressed into and through the web of material. In addition, it is strengthened film-sharing effect in the widening part of the application gap which gives a strongly uneven excess film.

The second method (Short Dwell), for coating of material webs are described in EP application 51698. Coating the material is then pressed into a chamber, which on the the outlet side of the terial web is limited by the dosing means and on its inlet side is limited by a, on one from the web of material limited distance arranged, assault plate and in the leading edge of a sealing means. Depending on the operating conditions, one flows between thirty- and thirty-fold applied amount forward over the assault plate.

Due to the lack of an application roller, the applicator becomes compact.

If the coating material is well suited for the paper web can .material web speeds of up to 600-700 m / min. and lower basis weights are achieved compared to what, in similar circumstances is possible with an applicator with a whole roller. Also the hydrodynamic pressure at the metering means is relatively low at low material web speed, whereby it is not always necessary necessary to provide a barrier layer before the dosing means. At velocities as above are also the derivation of the coating material relatively calm and even so that a full utilization of the material web is usually secured.

However, at high material web speeds, liquid pressure proportion fi üg fi at the dosing means and due to the barrier layer will be pressed in in, or through, the web of material.

In addition, the impulse increases at the material web formed the liquid boundary layer so strongly, especially at high dry substance content of the coating material, that of rigid sheets built-up dosing means yields to the pressure. The weight of it the applied material then rises considerably. Therefore, the basis weight becomes of the applied material, under similar conditions, as a rule lower with Flooded-Nip-Coaters than with Short-Dwell-Coaters at material track speeds exceeding 700 m / min. In addition, there is 465 112 in high-speed Short-Swell-Coaters another disadvantage, insofar as the coating material sprays out of control over the attack plate due to the fact that the air boundary layer, which is drawn in with the web of material in the application zone, in part may penetrate the dosing means, which may give rise to to uncoated portions on mate: ía1banan. The object of the present invention is to provide a device with which it is possible to, at relatively high material web speed, achieve a coating with consistently high quality and this even at low applied basis weight. This object is achieved according to the invention in that the applicator roller is provided with a articulation plate extending along the material of the applicator roller leading side all the way into the application gap between the guide roller and the counter roller.

The device for coating a continuous material web according to the invention offers considerable advantages.

By advancing the pre-dosed coating material all the way to the application gap between the application roller and the counter-roller, it becomes possible to adjust it between the rollers obtained hydrodynamic pressure within wider limits by changing the distance between the rollers, increasing the pressure decreases with increasing rolling distance. The coating material will flow more evenly, ie. without air containment and a larger amount will be spent on the gap so that the amount can exceed what is possible in Flooded-Nio-Coaters, in that at a lower hydrodynamic pressure internal vortex formation occurs as causes the risk of uncoated stains to decrease.

In practice, then only a pre-dosed amount of coating material is introduced into the application gap and that with it provided device is ensured that a well determined barrier layer in the coating material on the web of material is obtained read even at high material web speeds, prevents this barrier layer to the liquid pressure in the dispensing means 465 112 pushes the coating material too far into the material web.

By arranging the articulation plate, it is ensured that the coating the application material is fed to the application gap absolutely evenly, in both the running direction and the transverse direction of the material web, and free from air inclusions. In an embodiment of According to the invention, the hinge plate is curved at least in that area facing the application gap between the application roller and the counter roll, which curvature follows the circumference of the application roll.

This gives an exact control of the coating material, especially when the distance of the hinge plate to the application roller can changes. This makes it possible to set it exactly in hydrodynamic pressure obtained in the application gap and that also reproduce the same print. This is especially reduced the introduction of air inclusions, a particularly smooth one and flawless coating is obtained.

For smoothing pressure fluctuations, which for example can derived from the supply of coating materials, the the plate designed as a continuation of the upper edge of the liquid chamber for coating material in such a manner, that an outlet for excess coating material is formed between the fluid chamber and the lower portion of the joint plate in in the form of a slit or the like.

For continued management of the coating material is one articulated body arranged after the application gap seen in the coating the feed direction of the feed material, which joint body is provided with width drain openings for receiving coating material dispensed by means of a dosing means, wherein the lower and upper sides of the joint body are arranged at a distance from or with abutment against the applicator roller and the circumference of the roller.

To obtain a partial dewatering respectively a barrier layer in the coating material, the dosing the scheme includes a pre-dosing device and a finished dosing means. Preferably, the dosage means is constituted of a wiper strip, which at its facing the web of material 465 112 5 surface is in the direction of the pre-dosing means and in holding to the web of material converging, preferably convex converging.

Two preferred embodiments of the invention is shown in the accompanying drawing, in which Fig. 1 is a side view of the dosing and pre-dosing devices as well as the application Fig. 2 shows the process of coating a material Fig. 1, Fig. 3 is a side view of the dosage Fig. 1 and Fig. 4 is a view of the pre-dose device. the ring device in Fig. 3 seen from the front.

The application and pre-dosage shown in Fig. 1 the device comprises an applicator 1 with a rotatable application roller 2, which in a known manner feeds the coating the material from a liquid chamber 3, which is in communication with an inlet 4, to the application gap 7, which is arranged between the application roller 2 and one for supporting material web 5 arranged counter roll 6.

The pre-dosed coating material is fed between the circumferential surface of the applicator roller 2 and a guide plate 8 or more specifically up to the application gap 7. The distance 44 between the bearing plate 8 and the circumferential surface of the application roller can is controlled by means of an adjusting means 9 so that the dynamic pressures that arise in the coating material in the application gap can be adjusted and reproduced at a later time opportunity. The upper side of the hinge plate 8 is, on the side that is facing away from the application roller 2, provided with a drain surface 11, over which excess of the coating material can float away in the direction of the arrow 10 from the application gap 7 via a return line 12 and from there to a 13. From the assembly line 13, the coating line the collection material back to a collection box (not shown) vessel, from which it is returned to the inlet 4.

In the present case, the applicator roller 2 rotates and the counter roller 6 in opposite directions. Seen in the material web 465 112 6 direction of movement, a pre-dosing device 14 is arranged after the application gap 7. This pre-dosing device 14 comprises a pre-dosing means 15 in the form of a wiper strip, which leads into a support body 16 acting as holding means and is supported by a pressure hose 17. By regulating the pressure in the hose 17 can the dosing means 15 is adjusted with respect to the material web 5.

Mel] ¿an Pre-dosing device 14 and application gap fl fï is in itself a wedge-shaped tapered hinge body 18 arranged, which also serves as a guide for the coating material and is fifi gettw with overflow openings 19, through which the the stripped coating material is returned to the means a collecting vessel 21, from which the coating material via a return line 22 flows to the collection line 13. the upper and lower sides of the body 18 are arranged at a distance from the circumference of the application roller 2 and the counter-roller 6 or with abutment against the application roller 2 for effecting strict control and management of the coating material.

Seen in the running direction of the material web, a pre-dosing device 23 placed after the pre-dosing device 14. Completed the dosing device is provided with a rigid blade 24 whose holder means comprise a support beam 25, a clamping beam 26 and a clamping means 27. The pre-dosing device 23 is connected to an collection tray 28, which is connected to a collection tray. chamber 21 via an opening 29. The collection chamber is sealed against the liquid chamber 3 by means of a sealing flange 31. Pre-dosing the device 23 with associated collecting trough 28 is on the same methods, such as fi kdmærU @ smmrmüngm114 with associated collection chamber 21, arranged on a frame 32, which is pivotally mounted on a substantially horizontal axis 33, whereby both föymeyy @ 5_ the device 14 as the pre-dosing device 23 can be pivoted away, so that the applicator 1 is exposed for repair, cleaning doing, etc.

With reference to fig. 2 is described below on operating and dosing device operation at high material track speeds. Over the application roller 2 and by means of the articulation plate 8 the coating material is fed into the application gap 7 so that the paper or board web 5 is applied to the coating material the side facing the application roller 2. The application takes place of, 465 11.2 'i under a very low fluid pressure so that the penetration of the the aqueous constituents of the coating material become small as indicated by reference numeral 34 in Fig. 2. the laying material is applied in excess, the excess comes off coating material to float in the direction of the arrow 10 over the hinge plate 8 top and back to the collection bchâllarcn.

* The dosage means 15 has a convex and with respect to material web 5 converging front. The insoluble ñkdosenhgs- the means 15 functions with respect to the specific surface force in the at a lower force, so that the coating material is distributed evenly both in the running direction of the material web 5 and in a transverse direction the same, while only a slight penetration 34 is obtained.

Due to the geometric design, the pre-judgment means 15 is obtained a partial dewatering of a thin boundary layer 35 on the web of material 5, in which the solids of the coating material such as pigments and binders can be attached.

The presence of the boundary layer, or in other words the barrier layer 35 means that the coating material cannot penetrate like that far into the material web 5 as it passes the pre-dosing the body 24. The excessively dimmed and equalized the surplus of the coating material arriving at pre-dosing-- the means 24, in case of slight penetration 34, results in it abutment force required for pre-dosing can be reduced to a minimum. This results in a reduced wear of the finished product. the dosing means 24 and / or a longer basis weight is achieved at higher material web velocities and higher tower substance content in the coating material.

Figures 3 and 4 show a further embodiment of the hinge plate 8 shown in Fig. 1, which is here denoted by 8 '.

The other details are provided with the same reference drawings as in Fig. 1 and also has the same function in the description. In addition above, the hinge plate 8 'is arranged divided opposite the liquid chamber 3, wherein the dividing line 37 forms a horizontal plane with application roller 2 axis 38.

Between the hinge plate 8 'and the liquid chamber 3 is a slot 39 is provided, which ~ serves as a board drain for excess coating material, leaving a pile 465 112 accuracy is achieved with respect to the dosage.

For fixing the hinge plate 8 ', its two ends are inside the return line 12, provided with lugs 40, which are attached 421 in a shaft 41.

The shaft 41 is rotatably mounted in the return line 12 side wall and is inserted from its outside, its ends carries a torsionally fixed rotatable lever 42. The free end of the lever is connected to a pressure cylinder 43, with which the articulation plate 8 ' can be rotated around the shaft 41. For setting the feed slot 44 à outside and on both sides of the return line 12, in- adjustable stops 45 are provided, which are brought by means of the lever 42 for abutment when the hinge plate 8 'is in operating position.

For setting the output in the application column 7 projecting tip 50 on the articulation plate 8 ', a leaf spring 46 is provided. arranged, which by means of a screw 47 and an elastic liner 48 has a stiffening effect on the tip 50 of the hinge plate 8 through the lever effect. By turning the screw 47, the leaf spring 46 can free end 49, which protrudes into the application gap 7, is made to move up and down with the tip 50 of the hinge plate 8 'as the pivot point, wherein the gap 44 in the application gap can be further varied. This leaf spring 46 is also intended for the articulation plate 8 in Fig. 1.

The operation of the described device is as follows.

The coating material is pumped with excess into the liquid chamber 3, whereby a certain level is automatically obtained through the arranged board drain 39 so that the coating material that does not come with the roller 2 is removed by the return or the drain line 12 via the overflow drain 39. In this case, be taken into account that the overflow drain is dimensioned in such a way that it the coating material fed by the application roller 2 is fed forward with as low a pressure as possible through the gap 44, so that it the desired value of the hydrodynamic pressure is built up first in. the application gap 7. variations of the invention are possible. So, for example, W f @ ïmSe; fi @ S0qpnBt15 does not consist of a wiper strip but can also be a bent blade or roller wiper. Pre-dosing the body 24 may also, depending on the circumstances, consist of a bent blade or roller wiper.

Claims (8)

465 '(12 P a t e n t k r a v Device for continuous application of an even coating on a web of material (5) running over a counter roll (6), in particular a paper or cardboard web, which application is effected by means of an application roller arranged in a liquid chamber (3). (2), which carries the coating material and a dosing device provided with dosing means, characterized in that the application roller (2) is provided with a guide plate (8, 8 ') which extends along the material-carrying side of the application roller. all the way into the applicator slot (7) between the applicator roller (2) and the counter roller (6). Device according to claim 1, characterized in that the articulation plate (8, 8 ') is curved along the circumference of the application roller (2) at least within the area facing the application gap (7), between the application roller (2) and the counter roller ( 6). Device according to claim 1 or 2, characterized in that the articulation plate (8, 8 ') as a whole and / or partially is adjustable with respect to its distance (44) to the circumference of the application roller (2). A. Device according to any one of claims 1-3, characterized in that the hinge plate (8, 8 ') is designed as a continuation of the upper edge of the liquid chamber (3) for coating material in such a way that an outlet for excess coating material is formed between the liquid chamber (3) and the lower portion of the hinge plate (8, 8 ') in the form of a slot (39) or the like. Device according to one of Claims 1 to 4, characterized in that the dividing line between the articulation plate (8, 8 ') and the edge of the chamber substantially forms a horizontal plane with the axis (38) of the application roller (2). Device according to one of Claims 1 to 5, characterized in that a hinge body (8) is arranged after the application gap (7) as seen in the feed direction of the coating material, which hinge body is provided with width drain openings (19) for receiving coating material smeared by means of a dowel means (15), the lower and upper sides of the articulation body (18) being arranged at a distance from or abutting the applicator (2) and the counter (6). Device according to any one of claims 1-6, wherein the dosing device comprises a pre-dosing means (15) and a finished dosing means (24), characterized in that the pre-dosing means (15) operates with a lowest surface force with respect to the contact surface with the web of material (5). ) and that its leading edge is designed so that a partial dewatering is provided in a thin boundary layer (35) of the coating material on the side facing the web of material (5). Device according to claim 7, characterized in that the pre-dosing means (15) is a wiper strip and that its front side, which faces the material web (5) in the direction of the finished dosing means (24), has one with respect to the material web (5) converging, preferably convex converging form. O)