Method for improving strength and retention, and paper product

Abstract

A method for improving strength and retention in the manufacture of paper includes providing a composition containing microfibrillated cellulose in a fiber suspension, and from 0.1 to 10 w-% of microfibrillated cellulose by mass of the fiber suspension is added to improve the strength and retention of the product to be formed. A corresponding paper product is also provided.

1 . A method for producing a product in papermaking comprising:
 adding a composition comprising anionically modified microfibrillated cellulose to a fiber suspension at a concentration of 0.1 to 10 wt-% anionically modified microfibrillated cellulose by weight of the fiber suspension to produce a modified fiber suspension; and   forming the product from the modified fiber suspension,   wherein adding the anionically modified microfibrillated cellulose to the fiber suspension improves the strength of the product.   
     
     
         2 . The method of  claim 1 , wherein anionically modified microfibrillated cellulose is prepared by modifying and fibrillating cellulose or microfibril bundles comprising microfibrils. 
     
     
         3 . The method of  claim 1 , wherein anionically modified microfibrillated cellulose is anionically modified nanofibrillated cellulose. 
     
     
         4 . The method of  claim 1  comprising adding 0.1 to 2 wt-% of the anionically modified microfibrillated cellulose to the fiber suspension. 
     
     
         5 . The method of  claim 1  comprising adding about 1 wt-% of the anionically modified microfibrillated cellulose to the fiber suspension. 
     
     
         6 . The method of  claim 1 , wherein adding the anionically modified microfibrillated cellulose to the fiber suspension improves retention of the product. 
     
     
         7 . The method of  claim 1 , wherein the fiber suspension comprises fiber based pulp formed by a chemical method, a fiber based pulp formed by a mechanical method, or a combination thereof. 
     
     
         9 . The method of  claim 1  further comprising adding one or more fillers to the fiber suspension. 
     
     
         10 . The method of  claim 9 , wherein the one or more fillers comprises a cationic filler added to the fiber suspension before adding the anionically modified microfibrillated cellulose. 
     
     
         11 . The method of  claim 1 , wherein the composition further comprises a fiber-based solid material. 
     
     
         12 . The method of  claim 1 , wherein the fiber suspension comprises fines. 
     
     
         13 . The method of  claim 1  comprising adding a cationic polyelectrolyte to the composition. 
     
     
         14 . The method of  claim 1  comprising adding about 0.1 to about 2 wt-% of a cationic starch to the fiber suspension. 
     
     
         15 . The method of  claim 1  comprising adding an anionic polyelectrolyte to the composition. 
     
     
         16 . The method of  claim 1  comprising adding inorganic nano- and/or microparticles to the composition. 
     
     
         17 . The method of  claim 1 , wherein adding the composition to the fiber suspension improves bonding strength SB of the product. 
     
     
         18 . The method of  claim 1 , wherein adding the composition to the fiber suspension improves tensile strength of the product. 
     
     
         19 . The method of  claim 1 , wherein the product is paper. 
     
     
         20 . The method of  claim 1 , wherein the product is a product containing anionically modified microfibrillated cellulose. 
     
     
         21 . A method for manufacturing a modified fiber suspension, the method comprising
 adding a composition containing anionically modified microfibrillated cellulose to a fiber suspension at a concentration of 0.1 to 10 wt-% anionically modified microfibrillated cellulose by weight of the fiber suspension to produce a modified fiber suspension,   wherein adding the anionically modified microfibrillated cellulose to the fiber suspension improves the strength of the product.