A METHOD FOR THE PRODUCTION OF A COATED PAPER, PAPERBOARD OR FILM AND A COATED PAPER, PAPERBOARD OR FILM

Abstract

The present invention relates to a method for the production of a coated paper, paperboard or film, wherein the method comprises the steps of; providing a first suspension comprising cellulose fibers, applying the first suspension on a substrate to form a fibrous web, wherein the web has a first and a second side, providing a second suspension comprising micro fibrillated cellulose, applying the second suspension either to the first side of the fibrous web or to a surface of a drying equipment and conducting said fibrous web through the drying equipment whereby the second suspension is added to the first side of the web forming the coated paper, paperboard or film. The invention also relates to a paper, paperboard or film produced according to the method.

Claims

1. A method for the production of a coated paper, paperboard or film, wherein the method comprises the steps of: providing a first suspension comprising cellulose fibers, applying the first suspension on a substrate to form a fibrous web, wherein the web has a first and a second side, providing a second suspension comprising microfibrillated cellulose, applying the second suspension to a surface of a drying equipment and conducting said fibrous web through the drying equipment whereby the second suspension is added to the first side of the web forming the coated paper, paperboard or film.

2. The method according to claim 1 wherein the first suspension comprises between 0.01 weight-% to 20 weight-% of microfibrillated cellulose based on total dry weight of the suspension.

3. The method according to claim 1, wherein the first suspension comprises between 70 weight-% to 100 weight-% of microfibrillated cellulose based on total dry weight of the suspension.

4. The method according to claim 2 wherein the microfibrillated cellulose of the first suspension has a Schopper-Riegler value below 90.

5. The method according to claim 1 wherein the second suspension comprises 70 weight-% to 100 wt-% of microfibrillated cellulose based on total dry weight of the suspension.

6. The method according to claim 1 wherein the second suspension comprises microfibrillated cellulose with a Schopper-Riegler value above 95.

7. The method according to claim 1 wherein the second suspension is applied in an amount that a coating having a grammage of 0.1-8 gsm is formed.

8. The method according to claim 1 wherein the method further comprises the step of dewatering the formed fibrous web to a dry content of 25-90 wt-% before the web is conducted through the drying equipment.

9. The method according to claim 1 wherein the drying equipment used is a contact drying equipment such as a Yankee drying cylinder, a metal belt dryer, plastic belt dryer or a Condebelt drying equipment.

10. The method according to claim 1 wherein the method further comprises the step of applying a surface size, a foam coating and/or a dispersion coating comprising a polymer to the side of the paper, paperboard or film that has not been in direct contact with the contact drying equipment.

11. The method according to claim 1 wherein the method further comprises the step of applying a polymer layer to the side of the paper, paperboard or film that has not been in direct contact with the contact drying equipment, either through lamination of a polymer film or by extrusion coating of a polymer.

12. A coated paper or paperboard obtained by the method as claimed in claim 1.

13. A coated film comprising microfibrillated cellulose obtained by the method as claimed in claim 1.

14. The film according to claim 13 wherein the coated film has a grammage below 45 gsm.

15. The film according to claim 13 wherein the density of the film is above 700 kg/cm.sup.3.

16. The film according to claim 13 wherein the film has an Oxygen Transmission Rate (OTR) value (23 C., 50% RH) below 100 cc/m.sup.2*day*atm according to ASTM D-3985.

17. The film according to claim 13 wherein the film has a tear resistance above 2.0 Nm.sup.2/g measured as the geometric MD/CD mean value.

18. The film according to claim 13 wherein the first side of the film has a surface roughness PPS value below 2 m.

19. The film according to claim 13 wherein the coated film has a grammage below 35 gsm.

Description

BRIEF DESCRIPTION OF THE FIGURE

[0068] FIG. 1: Shows a schematic overview of the process according to the invention.

DETAILED DESCRIPTION OF THE FIGURE

[0069] FIG. 1 shows a schematic overview of the process according to the present invention. The first suspension (1) comprising cellulose fibers, e.g. microfibrillated cellulose is conducted to a substrate (2) on which a fibrous web (3) is formed. The substrate (2) is preferably a porous wire of a paper or paperboard machine. The substrate (2) and the fibrous web (3) is conducted through a drying equipment (4). To the surface (5) of the drying equipment is a second suspension (6) added. The second suspension is then applied onto the first side of fibrous web (3) which is the side in contact (via the coating of the second suspension) with the drying equipment (4). In this way a coated paper, paperboard or film is produced in a very easy and efficient way.

EXAMPLE

[0070] A first suspension comprising kraft pulp fibers were applied to a substrate to form a fibrous web. The fibrous web had a grammage about 60 gsm. A second suspension comprising 100% by weight of microfibrillated cellulose with a consistency of 4.5% by weight was added as a thin layer to a heated smooth metal surface. The temperature of the metal surface was about 150 C. The drying of the microfibrillated cellulose layer was started as water evaporated off from the heated metal surface. When the microfibrillated layer was still moist, the fibrous web was brought into contact with the microfibrillated cellulose layer located on the heated surface. Pressure was applied to ensure good contact between the fibrous web and the microfibrillated cellulose layer and to ensure that no wrinkles occurred.

[0071] After drying the coated paper product was easy to peel off the metal surface.

[0072] The resulted coated paper product had a very glossy and smooth surface. The surface visually looked like a polymer coated product. Consequently, the process according to the present invention made it possible to produce a coated paper product having good barrier properties as well as strength properties.

[0073] In view of the above detailed description of the present invention, other modifications and variations will become apparent to those skilled in the art. However, it should be apparent that such other modifications and variations may be effected without departing from the spirit and scope of the invention.