Method for increasing the strength of a paper or paperboard product
AssigneeInternational Paper Company
InventorsMartin A. Hubbe, Dinkar G. Wagle, Erwin R. Ruckel
Life of this patent
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Abstract
Processes for increasing the strength of cellulosic fibers are carried out by contacting relatively dry cellulosic fibers with an agent in particulate or vapor form comprising a carboxylic acid cyclic anhydride at an elevated temperature for a time sufficient to significantly increase the bonding strength of the fibers. The treated fibers bond more readily to one another and they also hold wet and dry strength aids more strongly. Furthermore, the treatment does not significantly affect the internal chemical structure of the fibers so that paper made from the fibers exhibits overall improved dimensional stability.
Claims23
A method for treating cellulosic fibers to improve the strength of the fibers which comprises contacting cellulosic fibers having a moisture content of about 20% or less with from about 0.01 to about 10 percent based on oven-dried weight of fibers of an agent in particulate form, non-hydrolyzed liquid form or vapor form comprising a carboxylic acid cyclic anhydride and heating the fibers and agent contacted therewith at a temperature ranging from about 50.degree. to about 120.degree. C. and for a time sufficient to substantially increase the bonding strength of the fibers.
A method for treating cellulosic fibers having a moisture content of about 20% or less by weight based on the oven dry weight of the fiber which comprises applying to the fibers an agent in particulate form, non-hydrolyzed liquid form or vapor form in an amount ranging from about 0.01 to about 10 percent based on oven-dried weight of fibers and thereafter heating the fibers at a temperature ranging from about 50.degree. to about 120.degree. C. and for a time sufficient to substantially increase the strength of the fibers and then contacting the fibers with a dilute basic solution followed by rinsing with water, wherein the agent comprises a carboxylic acid cyclic anhydride.
A method for treating cellulosic fibers to increase their strength which comprises mixing cellulosic fibers having a moisture content at or below about 20% by weight based on the oven dry weight of the fibers with from about 0.01 to about 10 percent particulate maleic anhydride based on oven-dried weight of fibers and heating the mixture at a temperature ranging from about 50.degree. to about 120.degree. C. which temperature is sufficient to significantly increase the carboxyl content of the fibers without significantly embrittling the fibers.
Dependencies are inferred from the claim text.