Ionic crosslinking of cotton

Cellulose crosslinking is a very important textile chemical process, and is the basis for a vast array of durable press- and crease-resistant finished textile products. N-methylol crosslinkers containing formaldehyde give fabrics desirable properties of mechanical stability (e.g. crease resistance, anti-curl, shrinkage resistance, durable press), but also impart strength loss and the potential to release formaldehyde, a known human carcinogen. Other systems, e.g. polycarboxylic acids, have been tested with varying degrees of success. We have developed methods of forming ionic crosslinks that provide outstanding crease-angle recovery performance, as well as complete strength retention in treated goods, without the potential for releasing any low-molecular weight reactive materials, such as formaldehyde. Our work is based on reactions of cellulose with materials that impart an ionic character to the cellulose, e.g. chloroacetic acid for negative charges or 3-chloro-2-hydroxypropyl trimethyl ammonium chloride for positive charges. These reactions produce ionic celluloses that can then sorb a polyionic material of opposite charge to form crosslinks. Cellulose treated with cationized chitosan after carboxymethylation showed significant increases in crease recovery angles without strength loss.