PRODUCTION OF HIGHLY STRETCHABLE PAPER HAVING SATISFACTORY SURFACE PROPERTIES

There is provided a method of producing uncoated paper having a grammage according to ISO 536 of 50-250 g/m 2， a Gurley value according to ISO 5636-5 of above 15 s and a stretchability according to ISO 1924-3 in the machine direction of at least 9 %， said method comprising the steps of:5 a) providing a pulp， preferably sulphate pulp; b) subjecting the pulp to high consistency (HC) refining; c) subjecting the pulp from step b) to low consistency (LC) refining; d) diluting the pulp from step c) and adding the diluted pulp to a forming wire to obtain a paper web having a dry content of 15-25 %， such as 17-23 %;10 e) pressing the paper web from step d) to a dry content of 30-50 %， such as 36-46 %; f) drying the paper web from step e); g) compacting the paper web from step f) in a Clupak unit at a moisture content of 20-50 %， such as 30-49 %， such as 35-49 %;15 h) drying the paper web from step g); and i) calendering the paper web from step h) in a soft nip calender or a long nip calender at a moisture content of 4-20 %， such as 5-12 %， such as 5-10 %. There is provided a method of producing uncoated paper having a grammage according to ISO 536 of 50-250 g/m2， a Gurley value according to ISO 5636-5 of above 15 s and a stretchability according to ISO 1924-3 in the machine direction of at least 9 %， said method comprising the steps of:5 a) providing a pulp， preferably sulphate pulp; b) subjecting the pulp to high consistency (HC) refining; c) subjecting the pulp from step b) to low consistency (LC) refining; d) diluting the pulp from step c) and adding the diluted pulp to a forming wire to obtain a paper web having a dry content of 15-25 %， such as 17-23 %;10 e) pressing the paper web from step d) to a dry content of 30-50 %， such as 36-46 %; f) drying the paper web from step e); g) compacting the paper web from step f) in a Clupak unit at a moisture content of 20-50 %， such as 30-49 %， such as 35-49 %;15 h) drying the paper web from step g); and i) calendering the paper web from step h) in a soft nip calender or a long nip calender at a moisture content of 4-20 %， such as 5-12 %， such as 5-10 %.