Lyocell (Tencel): Courtaulds versus Lenzing:
A disadvantage of the viscose process – and this was one of the reasons why several companies abandoned it – was that it was highly polluting. It used several toxic chemicals, most of which had to be disposed of as effluent. The search for a cleaner process, which began in the 1920s, was based on the idea that, instead of breaking up the cellulose extracted from woodpulp and regenerating it, cellulose might be dissolved directly using chemicals which would be easy to use and recover. The most promising solvent, first identified by two Swiss chemists in 1939, was an amine oxide, a non-toxic chemical, and this work was taken further after the war by Eastman Kodak in the US.
Eastman’s scientists filed their first solvent-spinning patent in 1966 but the company decided not to commercialise the process. American Enka, the US affiliate of the Dutch company Akzo, acquired the patents and made further improvements, principally in the solvent composition and in spinning. However, the company ran into problems when it tried to produce fibre on a large scale and spinning quality was poor. The Dutch parent company discontinued the work on solvent spinning and in 1985 sold American Enka to the German chemical company, BASF. The patents that American Enka had filed were put together in a manual and offered for sale.
(More to come)
The Eastman scientist who filed the first patent on NMMO as way of making cellulose dopes was Dee Lynn Johnson who moved to 3M later in his career. In the early 90's I was invited to give a talk on lyocell at 3M's Technical Center in Minneapolis and had the pleasure of meeting Dee, then recently retired. He was of course delighted that his cellulose dope idea was at last being commercialised to make Tencel fibre in Mobile.