Patent ID: 7109325

Claim:
A method of making a carboxylated cellulose product which comprises: oxidizing a cellulose by reacting it in an aqueous system with a sufficient amount of a primary oxidant selected from the group consisting of hindered cyclic nitroxides having the composition wherein R 1 –R 4 are one to four carbon alkyl groups but R 1 with R 2 and R 3 with R 4 may together be included in a five or six carbon alicyclic ring structure, X is methylene, oxygen, sulfur, or altylamino, and R 9 and R 10 are one to five carbon alkyl groups and may together be included in a five or six member ring structure which, in turn, may have one to four lower alkyl or hydroxy alkyl substituents; and a secondary oxidant selected from chlorine dioxide and latent sources of chlorine dioxide in a sufficient amount to induce an increase in carboxyl substitution in the carbohydrate of at least 2 meq/110 g, protecting the cellulose against degree of polymerization (D.P) loss by further treating the cellulose in aqueous suspension with a stabilizing agent selected from the group consisting of oxidizing agents and reducing agents in order to remove any substituents which tend to cause molecular chain breakage, and treating the carboxylated cellulose fibers with a peracid to stabilize the product by substantially converting any aldehyde substituents to additional carboxyl groups.