Paper for vertical form fill seal machine

Abstract

There is provided a Kraft paper, wherein: the grammage according to ISO 536 is 60-120 g/m2; the bending resistance index in the machine direction is 105-200 Nm7/kg3; the bending resistance index in the cross direction is 60-145 Nm7/kg3 (the bending resistance indexes are tested according to ISO 2493 using a bending angle of 15° and a test span length of 10 mm); the strain at break according to ISO 1924-3 in the machine direction is at least 3%; and the strain at break according to ISO 1924-3 in the cross direction is at least 5%.

1 . A method of forming a filled bag, comprising:
 providing a paper;   providing a vertical form fill sealing machine that comprises a forming shoulder, a forming tube, a longitudinal sealing arrangement, a cross/horizontal sealing and cutting arrangement;   introducing the paper to the forming shoulder and around the forming tube;   forming a bottom fin seal to form a bag;   introducing a product through the forming tube into the bag; and   forming a top fin seal;   wherein said paper has
 a grammage according to ISO 536 is 60-120 g/m 2 ; 
 a strain at break according to ISO 1924-3 in the machine direction is at least 3%; and 
 a strain at break according to ISO 1924-3 in the cross direction is at least 5%. 
   
     
     
         2 . The method of  claim 1 , wherein the paper has:
 a bending resistance index according to ISO 2493 in the machine direction is 105-200 Nm 6 /kg 3  and wherein the bending resistance is tested using a bending angle of 15° and a test span length of 10 mm; and   a bending resistance index according to ISO 2493 in the cross direction is 60-145 Nm 6 /kg 3  and wherein the bending resistance is tested using a bending angle of 15° and a test span length of 10 mm.   
     
     
         3 . The method of  claim 1 , wherein the paper is a Kraft paper. 
     
     
         4 . The method of  claim 3 , wherein the paper is a bleached Kraft paper. 
     
     
         5 . The method of  claim 4 , wherein the brightness of the bleached Kraft paper according to ISO 2470-1 is at least 70. 
     
     
         6 . The method of  claim 3 , wherein the paper is formed from a fiber suspension comprising softwood Kraft pulp. 
     
     
         7 . The method of  claim 6 , wherein the fiber suspension further comprises hardwood Kraft pulp. 
     
     
         8 . The method of  claim 7 , wherein hardwood pulp constitutes 5-50% of the dry weight of the fiber suspension and softwood pulp constitutes 50-95% of the dry weight of the fiber suspension. 
     
     
         9 . The method of  claim 1 , wherein the paper has a tear strength according to ISO 1974 in the machine direction is at least 780 mN. 
     
     
         10 . The method of  claim 1 , wherein the paper is creped. 
     
     
         11 . The method of  claim 1 , wherein the paper has:
 a tensile energy absorption according to ISO 1924-3 in the machine direction is at least 130 J/m 2 ; and   a tensile energy absorption according to ISO 1924-3 in the cross direction is at least 230 J/m 2 .   
     
     
         12 . The method of  claim 1 , wherein the paper has a Gurley porosity according to ISO 5636-5 is at least 29 s. 
     
     
         13 . The method of  claim 2 , wherein the bending resistance according to ISO 2493 in the machine direction is 45-105 mN. 
     
     
         14 . The method of  claim 1 , wherein the grammage according to ISO 536 is 60-100 g/m 2 . 
     
     
         15 . The method of  claim 1 , wherein the paper has:
 a bending resistance index according to ISO 2493 in the machine direction is 120-160 Nm 6 /kg 3  and wherein the bending resistance is tested using a bending angle of 15° and a test span length of 10 mm;   a bending resistance index according to ISO 2493 in the cross direction is 80-130 Nm 6 /kg 3  and wherein the bending resistance is tested using a bending angle of 15° and a test span length of 10 mm.   
     
     
         16 . The method of  claim 1 , wherein the paper has:
 the strain at break according to ISO 1924-3 in the machine direction is at least 3.5%; and   the strain at break according to ISO 1924-3 in the cross direction is at least 5.5%.   
     
     
         17 . The method of  claim 1 , wherein the paper has:
 a grammage according to ISO 536 is 70-90 g/m 2 ;   a bending resistance index according to ISO 2493 in the machine direction is 120-160 Nm 6 /kg 3  and wherein the bending resistance is tested using a bending angle of 15° and a test span length of 10 mm;   a bending resistance index according to ISO 2493 in the cross direction is 100-120 Nm 6 /kg 3  and wherein the bending resistance is tested using a bending angle of 15° and a test span length of 10 mm;   a strain at break according to ISO 1924-3 in the machine direction is 3.5-5%; and   a strain at break according to ISO 1924-3 in the cross direction is 6-12%.   
     
     
         18 . The method of  claim 1 , wherein the paper has a strain at break according to ISO 1924-3 in the cross direction is 6-10%. 
     
     
         19 . The method of  claim 4 , wherein the paper has a brightness according to ISO 2470-1 of 70-100. 
     
     
         20 . The method of  claim 9 , wherein the tear strength according to ISO 1974 in the machine direction is at least 800 mN. 
     
     
         21 . The method of  claim 10 , wherein paper is micro-creped. 
     
     
         22 . The method of  claim 11 , wherein:
 the tensile energy absorption according to ISO 1924-3 in the machine direction is 150-240 J/m 2 ; and   the tensile energy absorption according to ISO 1924-3 in the cross direction is 240-320 J/m 2 .   
     
     
         23 . The method of  claim 12 , wherein the Gurley porosity according to ISO 5636-5 is at least 35 s. 
     
     
         24 . The method of  claim 1 , the sealed bag is a gusseted bag. 
     
     
         25 . The method of  claim 1 , wherein the sealed bag is a pillow bag.