Alkali Pretreatment and Resin Finishing of Lyocell: Effect of Sodium Hydroxide Pretreatments

摘要

Lyocell fabric samples were pretreated with 2-8 mol/L sodium hydroxide (NaOH) and then resin-finished with dimethyloldihydroxyethylene urea, dimethyl dihydroxyethylene urea, and dimethylol urea based products. The resin-finishing treatments caused changes in the substrate properties, such as reduced accessibility, improved crease recovery, and reduced work of rupture and abrasion resistance. Differences were observed between resin-finished substrates as a function of the crosslinker type, and they were attributed to the influence of the crosslinker content and crosslink length in the substrates. The alkali pretreatments influenced the effects of resin finishing. A significant enhancement of the crosslinker penetration appeared within the substrates pretreated with 4 mol/L NaOH. Pretreatments with 6 and 8 mol/L NaOH also enhanced the crosslinker penetration, but the depth of catalyst penetration appeared to exceed that of the crosslinker; leading to demixing between the two components within the substrates. The penetration depth of a direct dye, C.I. Direct Red 81, appeared lower than that of the crosslinker in the alkali-pretreated substrates. Pretreatments with NaOH in the range of 4-8 mol/L appeared to create gradients of accessibility within fibers and yarns of lyocell fabrics, with the depth of reagent penetration increasing in the following order: C.I. Direct Red 81 < crosslinker < catalyst.