Nanotechnology-driven, computer-controlled, highly sustainable process for making paper and board

Abstract

In simple form the stock comprises water, cellulose fiber, pigment or filler, a cationic, charge-neutralizing chemical, and an anionic nanoparticle. The process introduces stock components in proper order, while homogenizing them towards molecular dimensions with low surface tension catalyst and vigorous mixing. The amount of catalyst is optimized for stock dispersion, and formation of an azeotrope in the dryer section. A classical nanostructure is formed. Solids exiting the press increase by as much as 6-7%; water removal energy in the dryer section is reduced in a 40-60% range. Homogeneity is maximized by controlling the standard deviation of a convenient process parameter. The system is controlled at zero zeta potential, at the specific filtration resistance level required for maximum productivity. Chemical usage is reduced by at least an order of magnitude. The process is highly sustainable.

1 . A method for papermaking, comprising:
 preparing a stock of water and pulp;   adding iso-paraffin to the stock, the iso-paraffin having a boiling point of 150° C. or greater, and a surface tension below 30 dynes/cm 2 .   forming a web of stock on a wire mesh;   pressing the web of stock including the iso-paraffin to remove water; and   drying the pressed web of stock to form paper.   
     
     
         2 . The method of  claim 1 , wherein
 the iso-paraffin is one or more iso-paraffins selected from the group consisting of ISOPAR G, ISOPAR H, ISOPAR L. ISOPAR M and ISOPAR V; produced by Exxon-Mobil.   
     
     
         3 . The method of  claim 1 , wherein
 the addition of iso-paraffin to the stock is performed before the formation of the web.   
     
     
         4 . The method of  claim 1 , wherein
 the addition of iso-paraffin to the stock is performed on the web of the stock before the pressing of the web.   
     
     
         5 . The method of  claim 3 , wherein the addition of iso-paraffin further comprises:
 forming a mixture of iso-paraffin and one or more additives selected from the group consisting of fillers, sizes, coloring agents, cationic chemicals, and anionic chemicals.   
     
     
         6 . The method of  claim 5 , wherein
 the formation of the mixture is performed by a high shear mixer, preferably utilizing ultrasonic energy.   
     
     
         7 . The method of  claim 5 , wherein
 an in-line static mixer is employed to mix the chemicals homogeneously with the stock.   
     
     
         8 . The method of  claim 7 , wherein
 a function of homogeneity is measured by first, for example, measuring the specific conductance, then calculating and outputting its standard deviation, and using this value to adjust the upstream parameters such as mixing energy input and chemical concentration, to maximize homogeneity by minimizing the amount of standard deviation.   
     
     
         9 . The method of  claim 4 , wherein the addition of iso-paraffin is performed by spraying iso-paraffin on the web. 
     
     
         10 . The method of  claim 7 , wherein the dispersion of iso-paraffin is created by mixing chemicals and iso-paraffin in a high shear mixer, preferably with ultrasonic energy. 
     
     
         11 . The method of  claim 1 , wherein the iso-paraffin is present in the stock in an amount of about 0.05 to 10% by weight stock. 
     
     
         12 . The method of  claim 1 , wherein the amount of iso-paraffin is about 0.5 to 2% by weight stock. 
     
     
         13 . The method of  claim 1  further comprising:
 adding cationic chemicals and anionic chemicals to the stock prior to forming a web of the stock, wherein the anionic chemical addition point is sufficiently downstream of the cationic chemicals that stock homogeneity is attained prior to reaching the anionic chemical addition point; determining the zeta potential of recirculating stock from a headbox of a paper making apparatus.   
     
     
         14 . The method of  claim 13  wherein the cationic chemicals are added simultaneously with adding the iso-paraffin to the stock with appropriate cationic functional chemical additives mixed thoroughly; and the anionic chemicals are likewise added simultaneously, preferably with an additional increment of iso-paraffin in the stock, with appropriate anionic chemical additives and mixed thoroughly; and
 the result is an increase in the functional chemical additive performance of at least one order of magnitude.   
     
     
         15 . The method of  claim 14  comprising controlling the zeta potential of stock recirculating from a headbox at zero millivolts by use of a computer programmed to balance the feed rates of cationic and anionic process chemicals to attain and maintain a continuous headbox stock value of zero millivolts. 
     
     
         16 . The method of  claim 15  in which the computer is programmed to maximize flow rates of both cationic and anionic process chemicals while maintaining zero zeta potential in the head box, thereby maximizing productivity. 
     
     
         17 . A stock used for making paper comprising:
 water, pulp and iso-paraffin preferably having a boiling point of 150° C. or greater and a surface tension below 30 dynes/cm 2 .   
     
     
         18 . The stock of  claim 14  further comprising:
 one or more additives selected from the group consisting of fillers, sizes, coloring agents, cationic and anionic chemicals, including functional chemical additives and process chemical additives.   
     
     
         19 . The stock of  claim 16  wherein
 the iso-paraffin is one or more iso-paraffins selected from the group consisting of ISOPAR G, ISOPAR H, ISOPAR L. ISOPAR M and ISOPAR V.   
     
     
         20 . The stock of  claim 16  wherein the iso-paraffin is present in an amount of about 0.05 to 2% by weight stock, and serves to improve water removal on the wet end and in the press section, thereby increasing energy efficiency. 
     
     
         21 . The stock of  claim 16  wherein the iso-paraffin is present in an amount of about 2.0 to 20% by weight of stock, and serves additionally to greatly improve dryer energy efficiency, reducing it by upwards of 50%. 
     
     
         22 . The finished product of  claim 16  which is re-processed as “broke”, wherein the addition of a cationic charge neutralizing chemical, such as a polydadmac, disperses the product particles to the original primary composition, such as fibers, fillers and fines, making the broke easy to re-process and the product highly sustainable.