Kyoko Machioka of Asahi Kasei Fibers Corp., Nobeka, Miyazaki (Japan) described the new microfibre version of the cuprammonium cellulose spunbond nonwoven.
Cotton linters are dissolved in cuprammonium hydroxide to give a 10% solution with twice the DP of viscose, and this very high viscosity solution can be extruded through large holes (0.5-0.7mm) and drawn as a liquid by over 100 times before regeneration to cellulose.
The new microfiber nonwoven has filaments of 3-5 micron diameter and gives fabrics with a third of the pore size of regular Bemliese®. Fibres are spun at 150 m/min after drawing by 500 times onto a belt running at 20-40 m/min. The fabric absorbency was said to be outstanding but no test data was provided. Vertical wicking appeared to be 50% higher than for the regular Bemliese.
How much copper remains in the nonwoven? Zero.