Process for making paper

Abstract

Methods for making paper or paperboard are described. One preferred method comprises forming a treated pulp by added to a papermaking pulp a synthetic layered silicate, a peptizer and at least one polymer. The synthetic layered silicate preferably comprises a synthetic hydrous sodium lithium magnesium silicate and the polymer is selected from cationic, nonionic and amphoteric polymers. The peptizer is preferably an inorganic polyphosphate peptizer and is contained in certain commercial synthetic layered silicate products. The inventor has surprisingly found that the peptizer provides significant improvements in drainage, retention and turbidity, thereby improving the papermaking process and the paper or paperboard product.

1 . A method of making paper or paperboard comprising: 
 (a) forming a treated pulp by adding to a papermaking pulp a synthetic layered silicate, a peptizer and at least one polymer, the synthetic layered silicate comprising a synthetic hydrous sodium lithium magnesium silicate and the at least one polymer comprising one or more members of the group consisting of cationic polymers, nonionic polymers and amphoteric polymers under cationic conditions; and    (b) forming the treated pulp into said paper or paperboard.    
     
     
         2 . The method of  claim 1 , wherein the synthetic layered silicate comprises laponite.  
     
     
         3 . The method of  claim 1 , wherein the synthetic layered silicate is added to the pulp in an amount of at least about 0.05 pound on a dry basis, per ton of pulp based on the dried solids weight of the pulp.  
     
     
         4 . The method of  claim 1 , wherein the synthetic layered silicate is added to the pulp in an amount of from about 0.1 pounds to about 5.0 pounds on a dry basis, per ton of pulp based on the dried solids weight of the pulp.  
     
     
         5 . The method of  claim 1 , wherein the synthetic layered silicate is added to the pulp in an amount of from about 0.2 pounds to about 1.0 pounds on a dry basis, per ton of pulp based on the dried solids weight of the pulp.  
     
     
         6 . The method of  claim 1 , wherein the peptizer comprises an inorganic polyphosphate peptizer.  
     
     
         7 . The method of  claim 1 , wherein the peptizer comprises tetrasodium pyrophosphate.  
     
     
         8 . The method of  claim 1 , wherein the synthetic layered silicate is added to the pulp in the form of an aqueous dispersion and wherein the dispersion contains said inorganic polyphosphate peptizer in an amount sufficient to maintain said dispersion in the form of a sol for a predetermined period of time.  
     
     
         9 . The method of  claim 5 , wherein the aqueous dispersion contains said synthetic layered silicate in an amount of up to about 10 wt %.  
     
     
         10 . The method of  claim 1 , wherein the cationic polymer is present and comprises a synthetic nitrogen-containing cationic polymer.  
     
     
         11 . The method of  claim 1 , wherein the cationic polymer is present and comprises one or more members of the group consisting of cationic polyacrylamides and copolymers thereof; and cationic diallyldimethylammonium chloride and copolymers thereof.  
     
     
         12 . The method of  claim 1 , wherein the cationic polymer is present and is added to the pulp in an amount of at least about 0.01 pound on a dry basis, per ton of pulp based on the dried solids weight of the pulp.  
     
     
         13 . The method of  claim 1 , wherein the cationic polymer is present and is added to the pulp in an amount of from about 0.1 pound to about 5 pounds on a dry basis, per ton of pulp based on the dried solids weight of the pulp.  
     
     
         14 . The method of  claim 1 , wherein the cationic polymer is present and is added to the pulp in an amount of from about 0.2 to about 2 pounds on a dry basis, per ton of pulp based on the dried solids weight of the pulp.  
     
     
         15 . The method of  claim 1 , further comprising shearing the pulp in one or more shear stages including a final high shear stage in which the pulp is passed through a screen prior to entering a headbox of a papermaking apparatus.  
     
     
         16 . The method of  claim 15 , wherein the polymer is added to the pulp before the final high shear stage and wherein the synthetic layered silicate is added to the pulp after the final high shear stage.  
     
     
         17 . The method of  claim 15 , wherein the synthetic layered silicate is added to the pulp before the final high shear stage and wherein the polymer is added to the pulp after the final high shear stage.  
     
     
         18 . A paper or paperboard made according to the method of  claim 1 .  
     
     
         19 . A papermaking apparatus comprising a supply of synthetic layered silicate, a supply of a papermaking pulp, a device for feeding the synthetic layered silicate from the supply of synthetic layered silicate to the supply of papermaking pulp, a supply of a retention system polymer, a device for feeding the retention system polymer from the supply of retention system polymer to the papermaking pulp, and a device for forming the pulp into a paper or paperboard after treatment with the synthetic layered silicate and the retention system polymer, wherein said retention system polymer is a cationic polymer, a nonionic polymer, or an amphoteric polymer under cationic conditions, or combinations thereof and wherein the synthetic layered silicate comprises a synthetic hydrous sodium lithium magnesium silicate and is fed to the papermaking pulp in the form of an aqueous dispersion which also includes an inorganic polyphosphate peptizer.  
     
     
         20 . The apparatus of  claim 19 , wherein the device for forming the pulp comprises a blend chest in communication with the supply of treated pulp, a fan pump in communication with the blend chest, a screen in communication with the fan pump, and a head box in communication with the screen.  
     
     
         21 . The apparatus of  claim 20 , wherein a supply tank is provided for holding a supply of the pulp, and the communication between the supply tank and the blend chest includes a refining apparatus for refining the pulp before entering the blend chest.  
     
     
         22 . The apparatus of  claim 20 , further comprising a white water silo, wherein the white water silo has an inlet in communication with said blend chest, an inlet in communication with the head box, and an outlet in communication with the fan pump.  
     
     
         23 . The apparatus of  claim 22 , further comprising one or more refiners for refining the pulp prior to forming the pulp in the head box.  
     
     
         24 . A paper or paperboard made from a drained paperweb, the paperweb comprising a treated pulp, the treated pulp comprising cellulosic fibers, synthetic hydrous sodium lithium magnesium silicate, at least one retention system polymer and an inorganic polyphosphate peptizer, said retention system polymer comprising a cationic polymer, a nonionic polymer, or an amphoteric polymer under cationic conditions, or combinations thereof.