Nonformaldehyde durable press finishing of cotton fabrics using the combination of maleic acid and sodium hypophosphite

Polycarboxylic acids have been used as nonformaldehyde crosslinking agents for cotton with sodium hypophosphite (NaH₂PO₂) as the catalyst to replace the formaldehyde-based dimethyloldihydroxyethleneurea (DMDHEU). Maleic acid (MA), an α, β-unsaturated bifunctional carboxylic acid, can esterify cotton but is not able to form crosslinking between two cellulose molecules by itself. In this research, we discovered that the wrinkle resistance of the cotton fabric treated with MA and NaH₂PO₂ was significantly increased and phosphorus was bound to cotton when the treated fabric was exposed to temperatures higher than that required for esterification of cotton by MA. Elevation of the fabric wrinkle resistance and increase in quantity of the phosphorus bound to cotton had similar dependency on curing temperature, on MA concentration, and on NaH₂PO₂ concentration. All the data support the hypothesis that H-P-(residual of NaH₂PO₂) added to >CC< of the MA already bound to cotton by esterification, thus forming a new crosslink between two cotton cellulose molecules. The cotton fabrics treated by MA/NaH₂PO₂ showed fabric wrinkle resistance similar to that treated with DMDHEU, but the breaking strength and tearing strength of the MA-treated cotton fabrics were significantly improved.