Improved recyclability of the superbase ionic liquid [MTBNH][AcO] used in the lyocell fiber spinning process

Abstract

In the research of new solvents for cellulose dissolution for textile fiber production, some ionic liquids offer high dissolving capacities making them attractive solvents for lyocell processes. One especially interesting group is superbase carboxylates. However, despite their excellent pulp dissolving abilities and good spinnability properties in a lyocell process, they have been lacking hydrolytic stability, which hinders their recyclability. In this article, a new type of superbase-based ionic liquid, [MTBNH][AcO], is aimed to provide higher hydrolytic stability than its structural relative predecessors. For evaluation of the hydrolysis behavior of [MTBNH][AcO], we have tested the ionic liquid in two sets of recycling experiments. The “blank-experiments” were applied to investigate hydrolytic behavior without the presence of pulp. These values were compared with the results from spinning trials with pulp. It was found that this new ionic liquid is not only more stable than its predecessor [MTBDH][AcO] in terms of hydrolysis but can also dissolve and spin cellulose at lower temperatures. The spun fibers were tested for their textile-physical properties and their performance was comparable to other lyocell fibers.