Esters of alkanedioic acids and citric acid as novel environment-friendly chemical finishes (crosslinkers) for cotton fabrics

摘要

Diethyl (ethane, propane, butane)dioates were transesterified each with citric acid, e.g., conc. sulfuric acid (0.01 mol) and citric acid (2 mols) were added to 1 mol (COOEt)_2 at 115-120 deg C for 30-60 min. Volatiles (EtOH) were driven off and the trans-ester (m. > 40 deg C) was dissolved in H_2O (50%) and used (60 g crosslinker/L; 6 g NaH_2PO_2 as catalyst) to crease- and shrinkproof a cotton fabric in a Benz two-roll padder at room temp. The fabric was squeezed, dried 5 min at 100 deg C, and crosslinked at 140-145 deg C for 300 s. At 135-145 deg C, the reaction time was 10-15 min, but the product was dark brown and its ester number was inferior. As the diester's inter-COOH alkyl chain length is increased, the trans-ester becomes more effective, presumably because the carboxyls become more accessible to active centers of cellulose. Diethyl butanedioate afforded the crosslinkers showing highest ester numbers and producing highest angles of unstressing in the fabrics examined.