EP3574144A1

EP3574144A1 - Curtain application unit and method for applying an application medium

Info

Publication number: EP3574144A1
Application number: EP18700287.8A
Authority: EP
Inventors: Tadashi Sasa; Akio Hirano; Hiroyuki Kohno; Christoph Henninger; Uwe Fröhlich; Toshihiro Katano
Original assignee: Voith Patent GmbH
Current assignee: Voith Patent GmbH
Priority date: 2017-01-25
Filing date: 2018-01-11
Publication date: 2019-12-04
Anticipated expiration: 2038-01-11
Also published as: CN110325683B; US20200038901A1; FI3574144T3; DE102017101373B4; DE102017101373A1; WO2018137932A1; EP3574144B1; US11407001B2; CN110325683A

Abstract

The invention relates to a curtain application unit for applying a liquid or pasty application medium to at least one surface of a moving material web, in particular a fibrous web, wherein the curtain application unit comprises an application nozzle, in particular a slotted nozzle, which is suitable for discharging a one-layer or multi-layer curtain under the influence of gravity and optionally under the influence of further forces on the surface of the material web, and a stripping device, which is suitable for keeping air dragged along with the material web away from the curtain. In addition, at least one further blocking device is provided, which is suitable for keeping air movements of the ambient air away from the curtain.

Description

Curtain application work and method for applying a coating medium

The invention relates to a curtain commissioned work according to the preamble of claim 1 and a method for coating a moving material web, in particular a fibrous web according to the preamble of claim 1 1st

In the production of fibrous webs such as paper or board webs, a coating, a so-called line, is frequently applied to one or both sides of the material web to improve the surface properties. For this purpose, coating has been established by means of a curtain applicator in recent years. In this case, a thin curtain of a liquid or pasty medium is deposited on the material web under the influence of gravity from a nozzle. In order to ensure a uniform application of the coating medium, a disturbance of the thin curtain must be largely avoided.

Particularly prone is such a curtain for air currents. Especially in applications where a large curtain height is needed or desired, or at low flow rates of coating color, the curtain is particularly sensitive.

Air currents occur in the environment of a paper machine in many places.

For example, drag material is carried along by the material web itself, which can disturb the curtain. To remove such air boundary layers, various devices for air boundary layer removal are known from the prior art. For example, DE 10 2008 040 419 and DE 10 2008 040 405 are cited.

However, a large number of air flows occur which are not induced by the moving material web. Causes of such currents may be moving parts of the machine, but also the hall ventilation or the movements of the operator. In order to keep such air currents away from the curtain, in the past the curtain coating plants have been enclosed, as for example in EP 1 538 263 shown. However, such an enclosure has some disadvantages. On the one hand, the enclosure must be made relatively large, so that the operating personnel can have access to the commissioned work for inspection and maintenance. Such a large enclosure not only requires a correspondingly large space in the machine hall, but is also associated with significant costs.

Furthermore, it is disadvantageous that in the maintenance and inspection, the operator must enter the enclosure. Here there is the danger that the movements of the operator air currents are generated within the enclosure, which can disturb the curtain.

Object of the present invention is therefore to propose a curtain commissioned work, in which the curtain remains largely unimpaired by air currents even at a larger curtain height or a lower order amount of application medium.

Another object of the invention is to enable maintenance and control of the curtain applicator, so that the curtain is not affected by the movements of the operator or only to a very limited extent.

The object is completely achieved by a curtain commissioned work according to the characterizing part of claim 1, as well as a method for coating a moving material web according to the characterizing part of claim 11.

In this case, a curtain coater is provided for applying a liquid or pasty application medium on at least one surface of a moving material web, in particular a fibrous web.

The curtain applicator comprises an application nozzle, in particular a slot nozzle, which is suitable for dispensing a single-layer or multi-layer curtain under the influence of gravity and, if appropriate, influence of further forces on the surface of the material web. Furthermore, the curtain applicator comprises a stripping device which is adapted to keep entrained with the material web drag air away from the curtain. According to the invention, at least one further locking device provided, which is adapted to keep air movements of the ambient air away from the curtain.

The further locking device according to the invention ensures that the curtain remains largely unaffected by air currents even at a greater curtain height.

In the execution and the arrangement of the other locking device has, as explained later, various possibilities, so that the curtain applicator can adapt to the circumstances of the installation situation, the run of the material web, etc., that a maintenance and inspection of the curtain Job is easily possible without the curtain is significantly influenced by the movements of the operator.

In particular, it may be possible by the invention to dispense with the usual complete housing of the curtain applicator together with a part of the running material web. This significantly simplifies the design and installation of the curtain applicator, a coating system, and also significantly reduces the costs incurred.

In general, all customary nozzles used in the area of the curtain application can be used as the application nozzle. Probably the most common types are on the one hand, the so-called 'slot-dies', in which the order medium from a in the

Usually machine-width slot exit, and can fall freely on the material web.

On the other hand, so-called 'slide-dies' are often used. With this kind

Application nozzle runs the application medium only a certain distance over a crooked

Surface before it hits the material web in free fall.

In the context of this invention, the application nozzles may also be suitable for the application of single-layer or multi-layer curtains.

However, the invention is not limited to these nozzle types.

Advantageous embodiments of the invention are described in the subclaims. For example, it may be provided that the distance of the opening of the application nozzle from the material web is at least 100 mm, preferably at least 200 mm, particularly preferably at least 300 mm. In such an embodiment, the drop height of the curtain during curtain application is comparatively very large. The curtain here is also very susceptible to disturbances, especially for air movements of the ambient air. The advantageous effect of the invention is particularly great in such an embodiment.

Furthermore, it can advantageously be provided that the at least one further blocking device is arranged in the direction of travel of the material web in front of the application nozzle.

In a particularly advantageous embodiment, it can be provided that the distance between the further blocking device and the application nozzle is less than 150 cm, in particular less than 100 cm, particularly preferably between 80 cm and 50 cm. As a result, for example, the risk can be reduced that air movements are generated in the space between the further barrier and the curtain applicator, which can interfere with the curtain.

In particular, it can be avoided by such a close arrangement that operating personnel can remain between the further blocking device and the curtain applicator during operation.

In a preferred embodiment, for example, it can be provided that the at least one further blocking device comprises a plate which is fastened to or in the immediate vicinity of the application nozzle and extends substantially parallel to the curtain. Such a plate can be viewed in the running direction of the material web, be mounted before or after the curtain. In a further, particularly preferred embodiment, a further plate can also be provided, which is attached to or in the immediate vicinity of the application nozzle. In that case, one plate will often be provided in front, and the other plate behind the curtain. In particular, it can be provided that one or both of these plates are provided at a distance from the curtain of less than 100 mm, preferably less than 50 mm.

In this embodiment of the invention, an extremely compact design of the curtain applicator is possible.

In a further advantageous embodiment of the invention, the further blocking device may comprise means for generating an air shield, in particular one or more air nozzles.

In particular, it can also be provided that the flow direction of the air of the air shield has a component which points away from the application nozzle and / or has a component which faces away from the material web.

The blocking effect of the further blocking device is realized in these embodiments in that a targeted air flow is generated, which, however, is directed so that it does not disturb the curtain. Often the placement of such a locking device will not be as close to the curtain as possible, such as the design as a plate to avoid disturbances of the curtain by the air shield itself. The air flow of the air shield should be dimensioned so strong that the air movements of the ambient air, which are generated for example by the movement of the operator, do not penetrate through the air shield.

To achieve the greatest possible barrier effect, the air shield will often extend at least over the width of the material web, or the width of the curtain, or go a little beyond.

Since the required air volumes and speeds can vary greatly depending on the installation and operating conditions, means for controlling or regulating the amount of air and / or air speed can be provided in particularly advantageous embodiments. Thus, the operator has the opportunity to optimally adjust the air shield.

Another great advantage of this air shield is that the operator can easily turn off the air shield for repair or maintenance work, or even easy to reach through the air shield. An optionally complex disassembly of a permanently installed rigid device can be omitted.

Thus, for example, for sampling of application medium from the curtain, a suitable collecting vessel or sample carrier can be guided through the air shield to the curtain. For this neither the order process has to be interrupted nor the air shield switched off.

In a further advantageous embodiment, it can be provided that the at least one further blocking device comprises at least two air nozzles for generating in each case one air shield, wherein one of the air nozzles are provided in front of and another air nozzle after the curtain. (Considered in the direction of the material web). In this case, the flow direction of the air of the at least two air shields each have a component which is directed towards the material web.

In this case, the two air nozzles are advantageously mounted close to the curtain, in particular it can be provided that one or both of these air shields are provided at a distance from the curtain of less than 100mm, preferably less than 50 mm. For this purpose, the nozzles can for example be attached directly to the application nozzle.

It is particularly advantageous if the two air shields or the air nozzles are provided at the same distance from the curtain. In particular, identical nozzles can be used.

Further, it is advantageous if the two air shields are symmetrical, that is, in particular their direction and / or their air velocity and / or the amount of air are the same, thus it can be prevented, for example, that even at a small distance of the air nozzles to the curtain by the Air shield itself is disturbed.

Advantageous air velocities for such an embodiment may be between 5 m / s and 50 m / s, in particular between 10 m / s and 15 m / s. With regard to the method, the object is achieved by a method for applying a liquid or pasty application medium on at least one surface of a moving material web by means of a curtain applicator, wherein from a applicator a single or multilayer curtain under the influence of gravity and possibly influence other forces on the Surface of the web is discharged, characterized in that entrained by the running web drag air is kept away from the curtain by means of a stripping and in addition by means of a further blocking device air currents of the ambient air are kept away from the curtain.

Advantageous embodiments of the method are specified in the subclaims.

Among other things, all the locking devices described above are suitable for the further locking device provided in the method. As commissioned commissioned works in particular according to one aspect of the invention are suitable.

An advantageous embodiment of the method is characterized in that the application medium through the application nozzle at a flow rate of less than 10 l / min ^* m, in particular less than 6 l / min ^* m, more preferably between 2 l / min ^* m and 5 l / min ^* m is applied. As a result, a comparatively thin curtain is generated, which can be influenced particularly easily by air movements of the ambient air. Here, the inventively provided further locking device is particularly advantageous. In particular, even if the drop height of the curtain is more than 100mm, more than 200 mm, or even 300mm and more.

In a further advantageous embodiment of the method it can be provided that the material web is moved at a speed of between 100 m / min and 800 m / min, in particular between 200 m / min and 600 m / min. In order to be able to realize even low application quantities per unit area at these speeds, the composition and / or the thickness of the Curtain can be adjusted accordingly, which in turn makes the curtain more susceptible to ambient air.

For the meaning of the flow rate, reference is made to the following Table 1. By way of example, for a coating color as a coating medium with a typical solids content of 63%, the necessary flow rates are given as a function of the production rate and the desired coating weight.

Table 1 Flow rates in 1 / min / m

As can be clearly seen in Table 1, it is very important for a wide range of applications to be able to stably realize a low flow order application. Among other things, for the embodiments shown in Table 1, the invention is very advantageous, in particular but not exclusively in combination with a height of the curtain of 100mm or more.

The line weights shown here between 8 g / m ² and 14 g / m ² are quite common. However, line weights of up to 20 g / m ² or more can also be realized with the method according to the invention or the device according to the invention.

The application medium can be, for example, a coating color for coating paper or other fibrous webs. The application medium usually contains a certain amount of solids. For example, in the case of coating colors, this may be CaCO 3, kaolin and / or ΤΊΟ 2, but other solids are also used.

In a particularly advantageous embodiment, the solids content of the application medium is between 55% and 72%.

Advantageously, the Brookfield viscosity (measured at 100 rpm) of the application medium can be between 100 mPas and 800 mPas, in particular between 300 mPas and 600 mPas.

In a particularly advantageous embodiment of the method, the further locking device can be realized by an air shield.

Depending on the application can also be provided that the air used for the air shield is processed. The treatment may include, for example, filtering and / or dehumidifying and / or heating.

Furthermore, it can be provided in the case of an air shield that the speed of the air of the air shield is between 15 m / s and 60 m / s.

In the following the invention will be explained in more detail with reference to schematic, not to scale figures.

Figure 1 shows a curtain applicator according to one aspect of the invention

Figures 2 and 2b each show a curtain applicator according to another aspect of the invention.

FIG. 3 shows a curtain applicator according to a further aspect of the invention.

The curtain applicator shown in Figure 1 comprises an applicator 1, from which a curtain 2 is applied under the influence of gravity on a material web 4, for example a paper or board web. The material web 4 is thereby by means of a deflecting roller 3 diverted that their course is substantially horizontal below the curtain 2. The impact point of the curtain is viewed here in the running direction of the material web 4 slightly behind the guide roller 3. The entrained with the material web 4 drag air is kept away from the curtain 2 here by a stripping device 5. As suitable stripping devices 5, for example so-called air knives (air-cut) are known in the industry. Frequently, the stripping device 5 extends to shortly before the point of impact of the curtain.

In FIG. 1, the at least one further blocking device 9, 9a, 9b according to the invention is realized in the form of two plates 9a and 9b. The two plates 9a, 9b are here fastened directly to the application nozzle. While it is in principle also possible to fix the plates elsewhere, the attachment directly to the application nozzle 1 has the advantage that the distance of the plates 9a, 9b to the curtain 2 is extremely low. Distances of less than 100mm, and even less than 50mm are feasible here. This leads to a very compact design. On top of that, the environment around the application nozzle, for example the deflection roller 3 or the stripping device 5, is freely accessible for maintenance work and the like during operation, without the curtain 2 being disturbed by the movement of ambient air.

FIG. 2 shows a curtain applicator according to a further aspect of the invention. Here, the at least one further locking device 9, 9a, 9b realized by an air shield 9. From an air nozzle 6, or a row of nozzles 6, the air exits to produce the air shield 9. The flow direction of the air, and thus the orientation of the air shield 9 can go vertically upwards, or be slightly inclined against this direction. Advantageously, this inclination will be directed away from the application nozzle 1, and thus also away from the curtain 2, in order to avoid influencing the curtain 2 by the air shield 9. Advantageously, the air shield 9 can extend at least over the entire width of the curtain 2 in the cross machine direction.

In the embodiment shown in FIG. 2, the air nozzle 6 or nozzle row 6 is fastened directly to the stripping device 5. This may be advantageous, but depending on the situation, other possibilities of attachment may be possible and useful. Advantageously, the distance of the air shield to the application nozzle may be less than 150 cm, in particular less than 100 cm, particularly preferably less than 50 cm. At distances of 80cm and less, for example, it is possible for machine operators to grasp the air shield 9 and perform work such as sampling at the nozzle or curtain.

As shown in Figure 2, usually after the curtain 2 another deflecting device such as e.g. a deflection roller 3a may be provided. The distance of this deflecting device 3a to the curtain 3 may vary in different installations.

The applicator shown in Figure 2b differs from that of Figure 2 in that it comprises a second locking device 9, which is provided after the curtain 2 and the applicator 1. This second locking device 9 is also realized by an air shield 9. From an air nozzle 6, or a row of nozzles 6, the air exits to produce the air shield 9. The direction of flow of the air, and thus the orientation of the air shield 9 can go as in the first locking device vertically upwards, or slightly inclined to this direction. Advantageously, this inclination will be directed away from the application nozzle 1, and thus also away from the curtain 2, in order to avoid influencing the curtain 2 by the air shield 9. Advantageously, the air shield 9 can extend at least over the entire width of the curtain 2 in the cross machine direction.

For the distance of this second locking device 9 from the curtain the same applies as for the first locking device. Again, distances between 80 cm and 50 cm are very beneficial. Due to the particular structural situation, such as the arrangement of the rollers 3a or the guidance of the web 4 but also larger or smaller distances can be selected.

FIG. 3 shows an embodiment in which the at least one further blocking device comprises at least two air nozzles for generating an air shield in each case. In this case, one of the air nozzles is provided in front of and another air nozzle after the curtain. (Considered in the direction of the material web). The The direction of flow of the air of the two air shields each have a component which points towards the material web.

In this case, the two air nozzles are advantageously mounted close to the curtain, the distance to the curtain may be less than 100mm, preferably less than 50 mm. In the embodiment of Figure 3, the nozzles are attached directly to the applicator nozzle. Thus, an extremely compact design of the curtain applicator is possible. Furthermore, the two air shields, or the air nozzles are provided at the same distance from the curtain. For identical nozzles can be used.

In addition, the two air shields are symmetrical, that is, in particular their direction and / or their air velocity and / or the amount of air are the same. This can be prevented that even at a small distance of the air nozzles to the curtain this is disturbed by the air shield itself.

Advantageous air velocities for such an embodiment may be between 5 m / s and 50 m / s, in particular between 10 m / s and 15 m / s.

Even if an example of a curtain applicator is shown in the figures, which applies a single-layer curtain, the invention is not limited thereto. Likewise, the known application nozzles 1 for two or more layers of curtains 2 can be used in a curtain applicator unit according to the invention. Although in the figures the application nozzle 1 is shown by way of example in the schematic form of a so-called 'slot die', illustrated embodiments can also be realized with other types of nozzles, for example so-called 'slot dies'.

Claims

claims

1 . Curtain applicator for applying a liquid or pasty application medium on at least one surface of a moving material web (4), in particular a fibrous web (4), wherein the curtain applicator an application nozzle (1), in particular a slot nozzle (1) comprises, which is suitable , a single or multi-layer curtain (2) under the influence of gravity and possibly influence of other forces on the surface of the material web (4) and further comprises a stripping device (5) which is suitable, with the material web (4) entrained drag air from the curtain (2) keep away from being characterized in that at least one further locking device (9, 9a, 9b) is provided which is adapted to keep air movements of the ambient air away from the curtain (2).

2. curtain coater according to claim 1, characterized in that the distance of the opening of the application nozzle (1) of the material web (4) is at least 100mm, preferably at least 200 mm, more preferably at least 300mm.

3. curtain applicator unit according to one of the preceding claims, characterized in that the at least one further locking device (9, 9a, 9b) in the running direction of the material web (4) in front of the application nozzle (1) is arranged.

4. curtain applicator unit according to one of the preceding claims, characterized in that the distance of the further locking device (9, 9a, 9b) to the application nozzle (1) less than 150cm, in particular less than 100cm, more preferably between 80cm and 50 cm.

5. curtain applicator unit according to one of the preceding claims, characterized in that the at least one further locking device (9, 9a, 9b) a Plate (9a, 9b) which is attached to or in the immediate vicinity of the application nozzle (1), and extends substantially parallel to the curtain (2).

6. curtain coating unit according to claim 5, characterized in that the further locking device (9, 9a, 9b) comprises a further plate (9b) which is attached to or in the immediate vicinity of the application nozzle (1), wherein the one plate (9a) in the running direction of the material web (4) in front of the curtain (2), and the further plate (9b) in the running direction of the material web (4) after the curtain (2) is mounted.

7. curtain applicator unit according to one of claims 4 or 5, characterized in that the distance of a plate (9 a) and / or the other

Plate (9b) to the curtain (2) is less than 100mm, preferably less than 50 mm.

8. curtain applicator unit according to one of the preceding claims, characterized in that the further locking device (9, 9a, 9b) comprises means for generating an air shield (9), in particular one or more air nozzles (6).

9. curtain applicator unit according to claim 8, characterized in that the flow direction of the air of the air shield (9) has a component which points away from the application nozzle (1) and / or has a component which away from the material web (4) has.

10. curtain applicator unit according to one of the preceding claims, characterized in that the at least one further locking device (9, 9a, 9b) at least two air nozzles (6) for generating in each case an air shield (9), wherein one of the air nozzles (6) before and a further air nozzle (6) after the curtain (2) are provided, and wherein the flow direction of the air of the at least two air shields (9) each having a component facing the material web.

1 1 .Verfahren for applying a liquid or pasty application medium on at least one surface of a moving material web (4) by means of a curtain applicator, wherein from a application nozzle (1) a single or multilayer curtain (2) under the influence of gravity and possibly influence another Forces on the surface of the material web (4) is discharged, characterized in that from the running material web (4) entrained drag air by means of a stripping device (5) is kept away from the curtain and additionally by means of another locking device (9, 9a, 9b) air flows the ambient air from the curtain (2) are kept away.

12. The method according to claim 10, characterized in that by the application nozzle (1) the application medium with a flow rate of less than 10 l / min ^* m, in particular less than 6 l / min ^* m, more preferably between 2 l / min ^* m and 5 l / min ^* m is applied.

13. The method according to any one of claims 10 or 1 1, characterized in that the material web (4) at a speed of between 100 m / min and 800 m / min, in particular between 200 m / min and 600 m / min is moved.

14. The method according to any one of claims 10 to 12, characterized in that the application medium has a solids content between 55% and 72%

15. The method according to any one of claims 10 to 13, characterized in that the Brookfield viscosity of the application medium at 100 U / min between 100 mPas and 800 mPas, in particular between 300 mPas and 600 mPas.