Covalent Bonding of Carboxylated Cellulose Fiber Webs

Abstract

Methods are provided for creating covalent bonding of webs by combining cellulosic fibers having a carboxyl content approximately greater than 7 meq/100 g with one or more crosslinking agents. In a first step, a carboxyl group is placed onto a fiber. In an embodiment, the fiber is then reacted with an oxazoline-functional polymer which has been combined with a polycarboxylate compound. Heat is applied to the treated web, and this enables formation of a cross-linked bridge in the form of a covalent bond. In an embodiment, the covalent bonding of the carboxylated cellulose pulp webs utilizes oxazoline-functional polymers and polyacrylic acid. The oxazoline polymer in combination with polyacrylic acid should form a network polymer with covalent bonds to the cellulose carboxyl groups. The non-woven web may be strengthhened by covalent bonding, thereby improving overall wet/dry strength of the final product.

1 . A method of covalent bonding of a cellulosic web, the method comprising the steps of:
 forming a web from highly carboxylated cellulose fibers;   applying a cross-linking agent to the highly carboxylated cellulose fibers to create a treated web; and   curing the treated web.   
     
     
         2 . The method of  claim 1  wherein the treated web is cured under heat. 
     
     
         3 . The method of  claim 1  wherein the treated web is cured under pressure. 
     
     
         4 . The method of  claim 1  wherein a carboxyl content of the fibers is approximately greater than 7 meq/100 grams. 
     
     
         5 . The method of  claim 1  wherein the crosslinking agent is a mixture of oxazoline functionalized polymer and polycarboxylate compound. 
     
     
         6 . The method of  claim 1  wherein the crosslinking agent is applied in an amount ranging from about 8 kg to about 100 kg chemical per ton of highly carboxylated cellulose fibers. 
     
     
         7 . The method of  claim 5  wherein the polycarboxylate compound is applied in an amount ranging from about 8 kg to about 100 kg chemical per ton of highly carboxylated cellulose fibers. 
     
     
         8 . A cellulosic web comprising:
 a highly carboxylated cellulose fiber;   a functionalized polymer; and   a polycarboxylate material;   wherein the functionalized polymer and the polycarboxylate material form a cross-linking agent and further wherein a covalent bond is formed between the highly carboxylated cellulose fiber and the cross-linking agent.   
     
     
         9 . The cellulosic web of  claim 8  wherein the functionalized polymer is an oxazoline-containing polymer. 
     
     
         10 . The cellulosic web of  claim 8  wherein the functionalized polymer is applied in an amount ranging from about 8 kg to about 100 kg chemical per ton of highly carboxylated cellulose fibers. 
     
     
         11 . The cellulosic web of  claim 8  wherein the polycarboxylate material is applied in an amount ranging from about 8 kg to about 100 kg chemical per ton of highly carboxylated cellulose fibers. 
     
     
         12 . The cellulosic web of  claim 8  wherein a carboxyl content of the highly carboxylated cellulose fibers is approximately greater than 7 meq/100 grams.