Coating device for applying coating color onto a fiber web and method for coating of a fiber web

Patent metadata

Field	Value
Publication number	US-9649658-B2
Application number	US-201514591727-A
Country	US
Kind code	B2
Filing date	Jan 7, 2015
Priority date	Jan 8, 2014
Publication date	May 16, 2017
Grant date	May 16, 2017

Abstract

A coating device and method for coating a fiber web for applying coating color onto a fiber web has a nozzle unit with at least one nozzle part ( 10 ), a feeding chamber ( 11 ) and at least one equalizing chamber ( 13; 13 ′), a feed hole ( 12 ) between the feeding chamber ( 11 ) and the first equalizing chamber ( 13 ), and a nozzle slot ( 14 ′) from which the coating color is discharged through the nozzle slot ( 14 ′) outlet opening ( 15 ). A mixing chamber ( 20 ) between the outlet area of the feed hole ( 12 ) and the equalizing chamber ( 13 ) functions as a means for distributing uniformly the inhomogeneous coating color flow entering the equalizing chamber ( 13 ) from the feed hole ( 12 ). The coating from the feed hole is directed to a wall ( 22 ) of mixing chambers ( 20 ) which distribute uniformly the coating entering the equalizing chamber ( 13 ).

First claim

We claim:

1. A coating device for applying coating color onto a fiber web, comprising:
a nozzle unit;
wherein the nozzle unit has at least one nozzle part;
wherein first portions of the nozzle part form a feeding chamber extending in a cross machine direction to form a manifold for coating color;
wherein second portions of the nozzle part form at least in part at least one equalizing chamber extending in the cross machine direction;
wherein third portions of the nozzle part form a plurality of feed holes spaced apart in the cross machine direction along the nozzle part, the plurality of feed holes defining a plurality of feed hole outlets;
wherein fourth portions of the nozzle part form a plurality of mixing chambers arrayed in the cross machine direction and opening into the equalizing chamber, and wherein each of the plurality of feed hole outlets opens into a corresponding one of the plurality of mixing chambers;
wherein each feed hole extends between the feeding chamber and the equalizing chamber via one of the mixing chambers;
wherein each mixing chamber has a wall surface opposite a corresponding one of the plurality of feed holes, the mixing chamber and the wall surface being arranged to distribute uniformly an inhomogeneous coating color flow entering the equalizing chamber from the corresponding one of the plurality of feed holes; and
a nozzle slot having an outlet opening, formed at least in part by a surface of the nozzle part, the nozzle slot being arranged to conduct coating color from the equalizing chamber to be discharged through the outlet opening of the nozzle slot onto an upper surface of the coating device;
wherein each mixing chamber has a curved bottom part and two opposed side walls that extend upwardly from the curved bottom part towards the equalizing chamber;
wherein each of the plurality of feed hole outlet openings is directed tangentially in respect to the corresponding curved bottom part of the mixing chamber.

2. The coating device of claim 1 wherein an opening angle B of less than 150° is defined between the two opposed side walls.

3. The coating device of claim 2 wherein the opening angle B is less than 90°.

4. The coating device of claim 3 wherein the opening angle B is less than 60°.

5. The coating device of claim 1 wherein the mixing chamber where it opens to the at least one equalizing chamber is round, or it is elliptic or oval so it extends in the cross machine direction.

6. The coating device of claim 1 wherein each of the plurality of feed holes defines a feed hole diameter which is between 1-5 mm.

7. The coating device of claim 6 wherein each of the plurality of feed holes defines a feed hole length which is at least 2-3 times the feed hole diameter.

8. The coating device of claim 6 wherein the curved bottom part has a radius greater than the feed hole diameter divided by 2.

9. The coating device of claim 8 wherein the radius is greater than 0.5 mm.

10. The coating device of claim 1 wherein the feed hole outlet opening is a distance of 0-5 mm from a bottom of the bottom part of the mixing chamber.

11. The coating device of claim 10 wherein the feed hole outlet opening is a distance of 0-3 mm from the bottom of the bottom part of the mixing chamber.

12. A method for coating of a fiber web, in a coating device comprising:
a nozzle unit having at least one nozzle part; wherein first portions of the nozzle part form a feeding chamber extending in a cross machine direction to form a manifold for coating color; wherein second portions of the nozzle part form at least in part at least one equalizing chamber extending in the cross machine direction; wherein third portions of the nozzle part form a plurality of feed holes spaced apart in the cross machine direction along the nozzle part, the plurality of feed holes defining a plurality of feed hole outlets; wherein fourth portions of the nozzle part form a plurality of mixing chambers arrayed in the cross machine direction and opening into the equalizing chamber, and wherein each of the plurality of feed hole outlets opens into a corresponding one of the plurality of mixing chambers; wherein each feed hole extends between the feeding chamber and the equalizing chamber via one of the mixing chambers; wherein each mixing chamber has a wall surface opposite a corresponding one of the plurality of feed holes, the mixing chamber and the wall surface being arranged to distribute uniformly an inhomogeneous coating color flow entering the equalizing chamber from the corresponding one of the plurality of feed holes; a nozzle slot having an outlet opening, formed at least in part by a surface of the nozzle part, the nozzle slot being arranged to conduct coating color from the equalizing chamber to be discharged through the outlet opening of the nozzle slot onto an upper surface of the coating device for applying coating color; wherein each mixing chamber has a curved bottom part and two opposed side walls that extend upwardly from the curved bottom part towards the equalizing chamber; wherein each of the plurality of feed hole outlet openings is directed tangentially in respect to the corresponding curved bottom part of the mixing chamber;
the method comprising the steps of:
feeding a coating color to the feeding chamber which extends in a cross machine direction and therefrom to the plurality of feed holes which extend in a machine direction, wherein the coating color develops an inhomogeneous viscosity as it flows;
discharging the coating color flow which forms an inhomogeneous viscosity flow from each of the plurality of feed holes into the plurality of mixing chambers each with an impact surface so that the coating color impinges on the impact surfaces;
subjecting the flow of coating color to a kinetic energy change by impacting the flow of coating color onto the impact surface with sufficient velocity to make friction unimportant and thereby mixing the coating color flow independent of viscosity;
uniformly feeding the flow of coating color from the mixing chambers to the equalizing chamber and then to the nozzle slot; and discharging coating color after mixing, through the outlet opening of the nozzle slot.

13. The method of claim 12 wherein each of the mixing chambers forming the opening area of the feed hole into the equalizing chamber distributes the coating color flow uniformly in the equalizing chamber indifferent of any inhomogeneity of the viscosity of the coating color flow.

14. The method of claim 12 wherein the direction of the coating color flow is changed immediately at the outlet from the feed hole into the mixing chamber.

15. The method of claim 12 wherein the plurality of feed holes have a diameter which defines a maximum shearing rate of the coating color flow in the feed holes wherein the diameter of the plurality of feed holes is 1-5 mm and flow velocity of the coating color flow is 2-7 m/s at the feed holes.

16. A coating device for applying coating color onto a fiber web, comprising:
a nozzle unit;
wherein the nozzle unit has at least one nozzle part;
wherein first portions of the nozzle part form a feeding chamber extending in a cross machine direction to form a manifold for coating color;
wherein second portions of the nozzle part form at least in part at least one equalizing chamber extending in the cross machine direction;
wherein third portions of the nozzle part form a plurality of feed holes spaced apart in the cross machine direction along the nozzle part, the plurality of feed holes defining a plurality of feed hole outlets;
wherein fourth portions of the nozzle p

Assignees

• Pitkäniemi Tapio
• Vatanen Heikki
• Valmet Technologies Inc

Inventors

• Pitkäniemi Tapio
• Vatanen Heikki

Classifications

• B05C9/06

  for applying two different liquids or other fluent materials, or the same liquid or other fluent material twice, to the same side of the work · CPC title

• Y10S118/04

  Curtain coater · CPC title

• D21H23/48

  Curtain coaters · CPC title

• B05C5/008 Primary

  Slide-hopper curtain coaters · CPC title

• B05D1/34

  Applying different liquids or other fluent materials simultaneously · CPC title