Arrangement in connection with curtain coating of a fibrous web

Patent metadata

Field	Value
Publication number	US-9808824-B2
Application number	US-201514850635-A
Country	US
Kind code	B2
Filing date	Sep 10, 2015
Priority date	Sep 11, 2014
Publication date	Nov 7, 2017
Grant date	Nov 7, 2017

Abstract

An arrangement in a curtain coater for starting and stopping coating of a web, having a reservoir and a connected surface extending over the web toward the curtain to collect the coating as the coater moves over the web to start coating the web. A cover plate that swing around a cross-direction shaft connected to the cover plate. In one embodiment the shaft also moves in the machine direction. The cover plate is used to protect an leading edge of the collecting surface from being covered with coating and pivots to be cleaned with fluid which may be supply from the shaft. The cover plate is arranged so the fluid drain off the cover plate onto the collecting surface or reservoir. When clean, the cover plate is repositioned to protect an leading edge of the collecting surface during the next start or stop operation of coating the web.

First claim

We claim:

1. A curtain coater, comprising:
a movable nozzle beam forming a coating material curtain for coating a fibrous web;
a return reservoir forming an upwardly opening reservoir, and a collecting surface which drains into the upwardly opening reservoir so as to receive coating material and cleaning fluid from above, the collecting surface extending to a tip in a direction which extends over the web toward the nozzle beam when the nozzle beam is positioned for coating the fibrous web, the collecting surface arranged to collect the coating material at least before or after the coating of the fibrous web;
a source of cleaning fluid positioned above the return reservoir;
a mechanism for moving the nozzle beam from a position over the return reservoir and the collecting surface to a position over the web for coating the web;
at least one support member for guiding the fibrous web below the coating material curtain when the nozzle beam is in the position over the web;
a cover plate movably mounted to swing around a pivoted shaft connected to the cover plate, the pivoted shaft extending in a cross-direction with respect to a direction of travel of the fibrous web;
wherein the cover plate is movable between at least two positions, a front position where the cover plate extends beyond the collecting surface tip and toward the coating material curtain positioned for coating the fibrous web and a cleaning position where the cover plate is located to extend above the collecting surface of the return reservoir and positioned with respect to the source of cleaning fluid such that cleaning fluids applied to the cover plate are conveyed to the return reservoir; and
wherein the cover plate is mounted for movement between the cleaning position and the front position.

2. The curtain coater of claim 1 wherein when the cover plate is located in the front position the coating material curtain is spaced a distance of 20-150 mm from the cover plate.

3. The curtain coater of claim 2 wherein when the cover plate is located in the front position the coating material curtain is spaced a distance of 50-100 mm from the cover plate.

4. The curtain coater of claim 1 wherein the cover plate is mounted for movement between the cleaning position and the front position by a swinging motion, and wherein the cover plate is connected to be driven by a speed limiting mechanism from the front position to the cleaning position;
wherein the speed limiting mechanism is arranged to have a speed which takes at least 10 seconds for a 90-degree swing.

5. The curtain coater of claim 4 wherein the speed limiting mechanism is arranged to have a speed which takes more than 15 seconds for a 90-degree swing.

6. The curtain coater of claim 1 wherein the cover plate has at least three positions, the front position, a back position and the cleaning position, and that the pivoted shaft and the swingably mounted cover plate are mounted for movement in a linear direction from the front position to the back position and away from the coating material curtain and, when in the back position, the cover plate is mounted to swing about the pivoted shaft into the cleaning position.

7. The curtain coater of claim 6 wherein the cover plate is connected to be driven by a speed limiting drive mechanism controlling the linear motion of the cover plate from the front position to back position;
wherein the speed limiting mechanism is arranged to have a speed of no more than 55 mm/s.

8. The curtain coater of claim 1 wherein the cover plate in the front position forms a guide plate for air flows passing in the vicinity of the coating material curtain.

9. The curtain coater of claim 1 wherein the pivoted shaft is connected to the source of cleaning fluid so that the cleaning fluid is conveyed via the pivoted shaft to clean the cover plate.

10. An arrangement for use in connection with curtain coating, having a movable nozzle beam forming a coating material curtain, the beam mounted for movement from a first position not over a moving supported fibrous web to a second position over the moving supported fibrous web, for coating a fibrous web, comprising:
a return reservoir forming an upwardly opening reservoir, and a collecting surface connected thereto which drains into the upwardly opening reservoir so as to receive coating material and cleaning fluid from above, the collecting surface extending in a first direction over the web toward the coating material curtain when the nozzle beam is positioned for coating the fibrous web in the second position, the collecting surface arranged to collect the coating material as the beam is moved from the first position to the second position;
a source of cleaning fluid positioned above the return reservoir;
a cover plate movably mounted to swing around a pivoted shaft connected to the cover plate, the pivoted shaft extending in a cross-direction with respect to a direction in which the fibrous web travels;
wherein the cover plate is mounted for movement between at least two positions, a front position where the cover plate extends beyond the collecting surface in the first direction and a cleaning position where the cover plate extends above the return reservoir such that cleaning liquid applied to the cover plate from the source of cleaning fluid will be conveyed to the return reservoir; and
wherein the cover plate is mounted for movement between the cleaning position and the front position.

11. The arrangement of claim 10 wherein when the cover plate is located in the front position the coating material curtain is spaced a distance of 20-150 mm from the cover plate.

12. The arrangement of claim 10 wherein when the cover plate is located in the front position the coating material curtain is spaced a distance of 50-100 mm from the cover plate.

13. The arrangement of claim 10 wherein the swinging motion of the cover plate is connected to be driven by a speed limiting mechanism from the front position to the cleaning position; and
wherein the speed limiting mechanism is arranged to have a speed which takes more than 10 seconds for a 90-degree swing.

14. The arrangement of claim 10 wherein the pivoted shaft is connected to a supply of cleaning fluid and the pivoted shaft comprises a source of cleaning fluid to clean the cover plate.

15. An arrangement for use in connection with curtain coating, having a movable nozzle beam forming a coating material curtain, the beam mounted for movement from a first position not over a moving supported fibrous web to a second position over the moving supported fibrous web, for coating a fibrous web, comprising:
a return reservoir forming an upwardly opening reservoir, and a collecting surface connected thereto which drains into the upwardly opening reservoir so as to receive coating material and cleaning fluid from above, the collecting surface extending in a first direction over the web toward the coating material curtain when the nozzle beam is positioned for coating the fibrous web in the second position, the collecting surface arranged to collect the coating material as the beam is moved from the first position to the second position;
a source of cleaning fluid positioned above the return reservoir;
a cover plate movably mounted to swing around a pivot shaft connected to the cover plate, the pivot shaft extending in a cross-direction with respect to a direction in which the fibrous web travels;
wherein the cover plate and the pivot shaft are mounted for linear movement to move in a second direction opposite the first direction;
wherein the cover plate is movable in the second direction be

Assignees

• Vatanen Heikki
• Nurmiainen Timo
• Valmet Technologies Inc

Inventors

• Vatanen Heikki
• Nurmiainen Timo

Classifications

• B05C11/1039

  Recovery of excess liquid or other fluent material; Controlling means therefor · CPC title

• D21H23/48

  Curtain coaters · CPC title

• B05C5/005 Primary

  Curtain coaters (B05C5/008 takes precedence) · CPC title