Flexible microfibrillated film formation

1. A method of manufacturing a film comprising microfibrillated cellulose, wherein the method comprises the steps of:

providing a first suspension comprising microfibrillated cellulose in an amount of at least 50 weight % based on the total weight of solids of the suspension, having a dry content of from 0.2 to 2.0%, wherein the first suspension has a first Schopper-Riegler (SR) value;

forming a first web of said suspension;

at least partly dewatering said first web;

applying a second suspension comprising microfibrillated cellulose onto a surface of said formed and at least partially dewatered first web, wherein the second suspension has a second Schopper-Riegler value which is higher than said first Schopper-Riegler value; and,

forming a film after the second suspension has been applied to said formed and at least partially dewatered first web.

2. The method as claimed in claim 1 , wherein said first suspension further comprises a filler material in an amount of from 3 to 40 weight %, based on the total weight of solids of the suspension.

3. The method as claimed in claim 1 , wherein said first suspension further comprises fibers in an amount from 5-50 weight %, based on the total weight of solids of the suspension.

4. The method as claimed in claim 1 , wherein said first suspension has a SR value in the range of from 40 to 90.

5. The method as claimed in claim 1 , wherein said second suspension further comprises at least one from a group consisting of: fines, fibers, fillers materials, retention chemicals, flocculation additives, deflocculating additives, wet strength chemicals, dry strength additives, softeners, or mixtures thereof.

6. The method as claimed in claim 1 , wherein said second suspension is provided to the surface of the first web in a head-box.

7. The method as claimed in claim 1 , wherein said second suspension is provided to the surface of the first web by a size press.

8. The method as claimed in claim 1 , wherein said second SR value is from 5% to 30% higher than said first SR value.

9. The method as claimed in claim 1 , wherein said second suspension has less dry content than the first suspension.

10. The method as claimed in claim 1 , wherein said second suspension is applied to the surface of the first web in the form of foam.

11. The method as claimed in claim 1 , wherein the method further comprises the step of dewatering the formed film.

12. The method as claimed in claim 11 , wherein the dewatering is performed by vacuum.

13. The method as claimed claim 11 , wherein the dewatering is performed by mechanical pressure.

14. A film obtained by the method as claimed in claim 1 , wherein the film has an oxygen transmission rate (OTR) of less than 500 ml/m 2 /24 h.

15. A film obtained by the method as claimed in claim 1 , wherein the film has a basis weight of less than 50 g/m 2 .

16. The method as claimed in claim 1 , wherein said first suspension further comprises a filler material in an amount of from 5 to 15 weight %, based on the total weight of solids of the suspension.

17. The method as claimed in claim 1 , wherein said first suspension further comprises long fibers in an amount of from 5 to 15 weight %, based on the total weight of solids of the suspension.

18. The method as claimed in claim 1 , wherein said first suspension has a SR value in the range of from 60 to 85.

19. A film obtained by the method as claimed in claim 1 , wherein the film has an oxygen transmission rate (OTR) of less than 50 ml/m 2 /24 h.

20. A film obtained by the method as claimed in claim 1 , wherein the film has an oxygen transmission rate (OTR) of less than 1 ml/m 2 /24 h.

21. A film obtained by the method as claimed in claim 1 , wherein the film has a basis weight of less than 35 g/m 2 .

22. A film obtained by the method as claimed in claim 1 , wherein the film has a basis weight of less than 20 g/m 2 .