Method to produce a film comprising microfibrillated cellulose and an amphoteric polymer

A method for the production of a film from a fibrous web, wherein the method comprises the steps of:

• providing a fibrous suspension comprising a microfibrillated cellulose, wherein the content of the microfibrillated cellulose of said suspension is in the range of 60 to 99.9 weight-% based on total dry solid content;
• adding an amphoteric polymer to said suspension to provide a mixture of said microfibrillated cellulose and said amphoteric polymer, wherein the amphoteric polymer is an amphoteric protein;
• providing said mixture to a substrate to form a fibrous web, wherein the amount of amphoteric polymer in said mixture is in the range of 0.1 to 20 kg/metric ton based on total dry solid content;
• and
• dewatering said fibrous web to form a film having a basis weight of less than 40 g/m2 and a density in the range of from 700 to 1000 kg/m3.

A method for the production of a film from a fibrous web, wherein the method comprises the steps of:

• providing a fibrous suspension comprising a microfibrillated cellulose, wherein the content of the microfibrillated cellulose of said suspension is in the range of 60 to 99.9 weight-% based on total dry solid content;
• adding an amphoteric polymer to said suspension to provide a mixture of said microfibrillated cellulose and said amphoteric polymer, wherein the amphoteric polymer is amphoteric starch;
• providing said mixture to a substrate to form a fibrous web, wherein the amount of amphoteric polymer in said mixture is in the range of 0.1 to 20 kg/metric ton based on total dry solid content;
• and
• dewatering said fibrous web to form a film having a basis weight of less than 40 g/m2 and a density in the range of from 700 to 1000 kg/m3.