Sunday, February 3, 2013

Pat White: 25 years of Tencel Development (2004)

Here's a summary of a rare public paper from Pat White, then Technical Director of Tencel Ltd and writing at the time of the Lenzing takeover.  It was given as the Keynote Speech at the 2004 TITK Alternative Cellulose conference in Rudolstadt Germany. 

Pat White leaving TITK with a present from TITK
Pat White, Tencel Ltd's Technical Director reviewed 25 years spent taking the lyocell process from curiosity to reality. Charged in 1979 with developing a low cost, environmentally-friendly route to rayon which would allow the venerable viscose process to retire gracefully, he rapidly identified NMMO as the most promising solvent. Fibres made from NMMO were all but indistinguishable from the premium Japanese polynosic rayon in character, so the key developments were to devise a highly efficient recovery system for the expensive solvent, and to optimise the process to deliver acceptable throughputs despite the solvent's tendency to degrade cellulose explosively if pushed too hard. The success of the engineering development coupled with a strong fashion-led Japanese demand for fibre led to rapid expansion and Lenzing's entry into the technology. The result: excess capacity because the projected long-term increase in fashion-sales proved unsustainable. Fibrillation and its control has dominated process and market development from the start:

  • The inherent fibrillatability of the first fibres led to the nonwovens market being targeted while solutions to the fibrillation “problem” were developed.
  • Japanese success at harnessing fibrillation to develop peach-touch fabrics by enzymatic selection of fibril sizes led to the first major sales, and to the optimism for rapid plant expansion.
  • New techniques were developed (by Tencel Ltd and “pioneering” mills) to cope with the new fibre in dyeing and finishing.
  • Low fibrillation achieved by process optimisation increased process costs but did not make the fibre universally acceptable in textiles.
  • Low fibrillation using additional on-line cross-linking increased the range of textiles possible.
  • High fibrillation routes were developed to suit special papers and wet nonwoven processes.

Currently, lyocell sales of ~90,000 tonnes/year are equally split between nonwovens, standard fibre in textiles and cross-linked fibre in textiles, with disposable wipes being the biggest single market. For the future, Mr White foresaw:

  • The Lenzing takeover of Tencel will achieve the “critical mass” to allow further development of the technology and markets.
  • Variable-cost reductions by moves to lower cost pulps and improved operating efficiency.
  • Fixed-cost reductions by integration, maximising factory output, and higher sales.
  • Lower cost processing to garments in Asia allowing lower costs to the consumer.
  • Further rapid expansion of nonwovens markets.
  • New products in the pipeline will further reduce costs and expand markets.

    from's summary of the paper which opened the 2004 Alternative Cellulose Conference at TITK Rudostadt

    The Original Paper is now available in full here.

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