Glyoxal as a Formaldehyde-Free Durable Press Reagent for Mild Curing Applications'

Abstract

The combination of aluminum sulfate and an α-hydroxy acid has proven highly effective in catalyzing the crosslinking of cotton cellulose by glyoxal under mild curing conditions. The durable press appearance ratings were increased by the presence of ethylene glycol as a coreactive additive, and a silanol-terminated silicone as softener. An unusual effect was observed with longer chain glycols, which cannot form 1:1 cyclic adducts with glyoxal as ethylene glycol does. The added glycols appeared to increase the efficiency of cellulose crosslinking by glyoxal, so that quite low curing temperatures and catalyst concentrations could be used. A preferential absorption and interaction of glyoxal with the cellulose may have occurred during the drying step to form complex cellulose hemiacetals, which subsequently interacted with added glycols to give the final crosslink structures during the heat cure. With diethylene glycol as eoreactant for glyoxal in a 1:1 mole ratio, curing at 1.15°C was effective in imparting a durable press rating of 4.0 with 298° conditioned wrinkle recovery (w + f) and 46-48% breaking or tearing strength retention in cotton printcloth. Fabric whiteness was equal or superior to that with dimethyloldihydroxyethyleneurea applied by a conventional pad-dry-cure treatment with magnesium chloride catalysis.