Monday 17 September 2012

The Genesis of Sustainable Fibres

25 years ago Courtaulds UK were about to start up the world’s first solvent-spun cellulose process to supply  25 tonnes/week  of  a new rayon fibre  with impeccable environmental credentials .  Process development had started in Courtaulds Coventry Research laboratories in 1979 under the direction of Patrick White[i]  and had remained secret under the “Genesis” codename until 1986.  In June that year the Courtaulds Fibres Viscose Division and Courtaulds Research joined forces to reveal, without spelling it out as such,  a long-range strategy to replace the chemically complex viscose route with a simple, pollution-free, physical cellulose dissolution route.  Here  cellulose in the form of wood-pulp would simply be dissolved without change and reprecipitated as a “lyocell” fibre.  Stratford-on-Avon was the chosen venue for the press conference and because nonwovens were then looking to be the best launch market, several nonwoven reporters[ii]  were present who duly wrote articles on the new fibre[iii].

At that press conference the process outline, the fibre properties,
and the high wet and dry latex and thermal-bonded nonwoven strengths obtained in pilot studies on the new fibres, were revealed. This was followed up in a paper given at Index 87 in Geneva in April[iv].  However work being carried out in Research on its performance in the then embryonic hydroentanglement bonding system and in papermaking was not revealed.  In fact what became the defining feature of the new fibre – its tendency to fibrillate into micro- and nano-fibres when abraded in the wet state – was not mentioned .  Fibrillation was seen as the problem which was making the dyeing, finishing and laundering of conventional textiles complicated. 

Also at that press conference, plans for an immediate expansion of the Coventry  50kg fibre-batch production system to a 1 tonne/week continuous line were mentioned.  Courtaulds even revealed  a plant was to be built in the USA “as soon as commercially feasible” , which in reality would be after proving the scale-up to the 25 tonne/week “S25”  line  then being planned  for installation at Grimsby at the end of 1987.

It’s interesting, in the light of over a quarter century of further development, to read again the 1986 documents used to justify the spending of several million pounds on  the S25 lyocell process scale-up which would also be used to commercialise what was later branded “Tencel”.  At that time, one customer, Chicopee[v], was bidding to take all the fibre, as it became available, for their “water jet entanglement” process for making wipes and surgical swabs.  J R Crompton[vi]  were evaluating it as a manila-hemp replacement in tea bags and food casings and had highlighted the possibility of 100% lyocell papers being possible given the right equipment to fibrillate the fibre.  Courtaulds own nonwoven operation,  Bonded Fibre Fabrics at Bridgwater, had interests in developing new latex-bonded fabrics, and Freudenberg saw it as a replacement for cotton in dry-laid interlinings, and polyester in wet-laid.

In the event, fibrillation proved  an unexpected advantage in apparel textiles and allowed fibrillated Tencel to be launched, much to the accountant’s delight, at the peak of an early 90’s Japanese fashion-tsunami  for soft-touch denim and other “peach-skin” garments.  The more price-sensitive nonwoven markets would have to wait until the public demand for sustainable disposables in harmony with nature increased, and of course  until the Tencel production capacity was large enough to support major new markets. 

With the recently announced expansion of Tencel by the current owners Lenzing (ref) , maybe that time has at last arrived.

[i] Patrick led the project for the next 20 years and was awarded an MBE for his efforts.
[ii] Lydia Cain (Nonwoven Markets), Derek Ward (Nonwovens Report International) and Peter Lennox-Kerr were among them.
[iii] One has surfaced so far thanks to David Allan, Editor of Nonwoven Markets Newsletter.  It was in the June 7th 1986 edition.
[iv] “Solvent-Spun Cellulosic Fibre in Nonwovens” by Smith, Williams and Woodings, INDEX 87 Congress Papers, published by EDANA.
[v] Then the nonwoven manufacturing division of Johnson and Johnson.  Now part of PGI.
[vi] Now part of Glatfelter UK

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