Chemical Agent
Cross-linking of cellulose chains in cotton fabrics is achieved using a bifunctional reactant to impart wrinkle resistance and dimensional stability. This compound, chemically termed dmdheu, forms covalent bonds with the hydroxyl groups of adjacent cellulose molecules under acidic conditions. The treated fabric retains its pressed shape and resists shrinkage through repeated laundering cycles.
Reaction Mechanism
Curing occurs at elevated temperatures in the presence of a magnesium chloride catalyst to initiate the etherification reaction. The chemical structure contains methylol groups that react with cellulose during the dry heating phase of finishing. This cross-linking prevents the slip of polymer chains when the fibre is wet, which is the primary cause of cotton creasing.
Fabric Modification
Application of this finishing agent takes place via a pad-dry-cure method in the textile finishing mill. While crease recovery increases, the cross-linking reduces the natural flexibility of the cotton fibres. This results in a notable loss in tensile and tear strength, meaning that finishing recipes must balance wrinkle resistance against fabric durability to prevent premature garment wear, especially along the folded edges and seams of trousers and shirts.
Technical Boundary
Durable press treatments are restricted to cellulosic fibres and their blends with synthetic polyester. The reaction does not occur on pure synthetic textiles like nylon or acrylic. It remains the baseline chemistry for durable press apparel finishing before low-formaldehyde alternatives are selected.