Process for improving dry strength and drainage of paper and paperboard

Abstract

A process is provided of providing glyoxylated polymer additives to a paper making process which brings about improvements in drainage properties of a cellulosic pulp material along with the ability to increase the dry strength of a resulting paper product. The process uses concentrated glyoxal to generate a working solution of a glyoxylated polymer additive which can be generated on site in a paper mill and used within a 24 to 48 hour interval. The ability to glyoxylate polymers in a working solution concentration provides for a more active additive and which can be supplied in a more economical fashion than conventional glyoxylated polymers.

1 . A method of improving drainage properties of fibers in a papermaking process comprising: 
 providing a stock solution of glyoxal at a concentration of between about 25% to about 40%;    adding a quantity of said stock solution of glyoxal to a polyacrylamide polymer to produce a solids working solution of a glyoxylated polyacrylamide polymer, said glyoxal being present at about 15% to about 25% by dry weight relative to the dry weight of said polymer;    adjusting said pH of said working solution to between about 7.8 to about 8.0;    metering said pH adjusted working solution into an aqueous suspension of a cellulosic pulp at a loading level of at least about 3 lbs of glyoxylated polyacrylamide per ton of fiber solids; and,    mixing said cellulosic pulp and said metered pH adjusted solution, thereby increasing the drainage properties of said cellulosic pulp.    
   
   
       2 . A method of improving the dry strength of a paper product comprising: 
 providing a stock solution of glyoxal at a concentration of between about 25% to about 40%;    adding a quantity of said stock solution of glyoxal to a strength additive selected from the group consisting of cationic starch, PAM, and combinations thereof, to produce an about 4% to about 6% solids working solution of a glyoxylated polyacrylamide polymer, said glyoxal being present at about 30% by dry weight relative to the dry weight of said strength additive;    adjusting said pH of said working solution to between about 7.8 to about 8.0;    metering said pH adjusted working solution into an aqueous suspension of a cellulosic pulp at a loading level of at least about 3 lbs of glyoxylated polyacrylamide per ton of fiber solids; and,    mixing said cellulosic pulp and said metered pH adjusted solution, thereby increasing the strength properties of cellulosic sheets made from said cellulosic pulp.    
   
   
       3 . A method of improving the dry strength of a paper product comprising: 
 providing a stock solution of glyoxal at a concentration of between about 25% to about 40%;    adding a quantity of said stock solution of glyoxal to a strength additive selected from the group consisting of cationic starch, PAM, and combinations thereof, to produce an about 4% to about 6% solids working solution of a glyoxylated polyacrylamide polymer, said glyoxal being present at about 30% by dry weight relative to the dry weight of said strength additive;    adjusting said pH of said working solution to between about 7.8 to about 8.0;    spraying said working solution onto a surface of a paper web at a dosage of about 3 to about 5 pounds of glyoxylated polyacrylamide on a solids basis to a ton of dry paper; and,    drying said paper web and said working solution, thereby increasing the strength properties of the resulting dried cellulosic product.