Geoffrey Owen's Tencel lyocell history extracts (part 2)

Geoffrey Owen of the Department of Management, London School of Economics presented a paper at SPRU in October this year entitled "Innovation in the man-made fibres industry: corporate strategy and national institutions." It is based on unpublished material made available to the author by Akzo Nobel, Lenzing and Courtaulds (amongst others) and is available in full here on the web as a PDF file.  It contains excellent sections on Tencel lyocell development history, the second extract of which is reproduced below:

Courtaulds and Tencel
Courtaulds was aware of what American Enka had been doing and their researchers saw that the solvent spinning process, if it could be made to work, might have important advantages. In 1979 a research team was set up in Coventry under Pat White, who had earlier worked on carbon fibre, to examine the process in detail; the programme was subsequently called the Genesis project. Although Courtaulds was under financial pressure at that time and several research programmes were cancelled, senior managers could see that the new process might be a way of reinvigorating the cellulosic fibres business (see Appendix 2 for a description of the solvent spinning process.)
The first laboratory-scale production began in 1981, and it was scaled up to a small pilot plant in 1983.  A note to the Board from the research department commented that the process looked extremely promising “in the sense that we believe it should be possible to produce a fibre with properties superior to viscose at lower cost…If we can succeed, this project could confound the conventional wisdom that there will be no new high volume fibre before the end of the century. It offers the possibility of transforming the prospects of our cellulosic fibre business”.

Courtaulds hired American Enka’s former research director, Bill Mathis, as a consultant. He confirmed that Courtaulds had taken a different approach to that taken by Enka and had solved some of the scaling-up problems. Courtaulds subsequently decided not to acquire an American Enka licence; it was regarded as expensive and unnecessary since White and his team were making good progress without it. Yet there were still many technical issues to be resolved.  One was to achieve a high recovery rate for the solvent which was much more expensive than the chemicals used for viscose. Another was to find a stabiliser to prevent the solvent from degrading and discolouring the cellulose. There were also difficulties in developing machinery that could dissolve the cellulose in a reliably continuous way. The published Enka route using extruders proved unsuitable for volume production. Courtaulds found an alternative route, using a Kraus Maffei horizontal mixer, and this was used in the pilot plant. It was later discovered that a more suitable machine was a vertical mixer, known as a filmtruder.

(more to come)

Early Tencel History from "Regenerated Cellulose Fibres"

Regenerated Cellulose Fibres published by Woodhead Publishing Ltd in 2001 contains a history of the Tencel development, the first extract of which appears below. (see the original for references)

Direct Dissolution in Amine Oxide: Lyocell

Lyocell technology was pioneered in the USA by Eastman Kodak and American Enka, but it was Courtaulds in the UK who persisted with development until a commercially viable fibre process emerged. Furthermore, Courtaulds did it at a time in its history when the very wisdom of continued involvement, not just in cellulosics but in any fibre or textile activity, was being called into question.

As early as the mid 1950's, Courtaulds believed the future of viscose to be so unattractive that it started to divert viscose profits not only into other fibres, but also into totally unrelated businesses.

By the late fifties, despite accounting for 80-90% of Courtaulds earnings, the reality of viscose's decline was becoming apparent. The usual remedies, reducing costs, improving quality, selling more aggressively and internationally were yielding diminishing returns so the Board's reaction was a new strategy involving:

• Developing new internal sources of profit i.e. utilising the viscose wet-spinning expertise to move into wet-spun acrylic fibres ("Courtelle"), and opening up a vast, and with hind-sight, transient, new market for a coarse and tough viscose in tufted carpets. ("Evlan")
• Developing new external sources of profit by acquisitions in "related but different" products, in reality British Celanese (Cellulose acetate fibres and related products) and Pinchin Johnson Paints (Later renamed International Paint)
• Developing greater market power by acquiring key elements of the rest of the fibre value-chain - "Verticalisation" - resulting most notably in the acquisition of the Lancashire Cotton Corporation Ltd and Fine Spinners and Doublers. (representing about 35% of the entire Lancashire cotton industry.)

Of these three, a) was least favoured with funds. Furthermore, little emphasis was placed on modernisation of regenerated cellulose fibre production methods

Early Tencel History from "Regenerated Cellulose Fibres" (part 4)

Regenerated Cellulose Fibres published by Woodhead Publishing Ltd in 2001 contains a history of the Tencel development, the fourth extract of which appears below. (see the original for references - click here for first extract)

Other Routes

Work on other routes to cellulosic fibres has continued, often driven by a desire to utilize the large capital investment in the xanthate route and hence cost less than a completely new fibre process.

The Finnish viscose producer Kemira Oy Saeteri collaborated with Neste Oy on the development of a carbamate derivative route. This system was based on the original work of Hill and Jacobsen who showed that the reaction between cellulose and urea gave a derivative which was easily dissolved in dilute sodium hydroxide:

Cell-OH + NH₂ -CO-NH₂ ---> Cell-O-NH₂ +NH₃

Neste patented an industrial route to a cellulose carbamate pulp which was stable enough to be shipped into rayon plants for dissolution as if it were xanthate. The carbamate solution could be spun into sulphuric acid or sodium carbonate solutions, to give fibres which when completely regenerated had similar properties to viscose rayon. When incompletely regenerated they were sufficiently self-bonding for use in papermaking. The process was said to be cheaper than the viscose route and to have a lower environmental impact. It has not been commercialised, so no confirmation of its potential is yet available.

Chen, working on a small scale at Purdue University, claims that solutions containing 10-15% cellulose in 55-80% aqueous zinc chloride can be spun into alcohol or acetone baths to give fibres with strengths of 1.5 to 2 g/den. However, if these fibres were strain-dried (i.e stretched) and rewetted whilst under strain, strengths of 5.2 g/d were achieved.

Kamide and co-workers at Asahi have been applying the steam explosion treatment to dissolving- pulp to make it dissolve directly in sodium hydroxide. In technical papers,, they claimed a solution of 5% of steam-exploded cellulose in 9.1% NaOH at 4^oC being spun into 20% H₂SO₄ at 5­^oC. The apparently poor fibre properties (best results being 1.8 g/d tenacity dry, with 7.3% extension) probably arise because the fibres were syringe extruded at 75 denier/fil. Asahi felt at the time that this would be the ultimate process for large scale production of regenerated cellulose fibres but in reality it’s use appears confined to the production of thickeners.

Chanzy, Peguy and co-workers at the Plant Macromolecules Research Centre (CERMAV-CNRS) in Grenoble studied the cellulose/NMMO system in depth; one paper indicating that further strength increases can be obtained by adding ammonium chloride or calcium chloride to the dope.

Lenzing back in the black (1998)

Lenzing has swung back into profit thanks to a good performance from its fibre and non-fibre related businesses.

Pre-tax profits were Sch222.9m ($18.7m) for the first three quarters, comparing favourably with a Sch242.2m loss for this period last year.

Turnover increased to Sch6.4bn in the first nine months of 1998 compared with Sch5.73bn in quarters one-to-three of last year.

Lenzing has warned that international financial turbulence has hit the world's textile fibre market, especially in Europe, where import pressure from Asian textiles is increasing.

Viscose consumption also declined, making market conditions difficult for the company in the US throughout the third quarter.

Cotton and polyester fibre prices are down, especially in Asia, and the company blames changes in fashion trends and a fall-off in Japanese demand for the underperformance of its Lenzing Lyocell fibre.

However, the company's Indonesian associate, South Pacific Viscose, is benefiting from favourable raw material prices, and achieving record production levels.

Despite the Lyocell setbacks, Lenzing forecasts satisfactory performance for the remaining quarter of 1998.

23 November 1998  [Source: ICB]

Early Tencel History from "Regenerated Cellulose Fibres" (part 2)

Regenerated Cellulose Fibres published by Woodhead Publishing Ltd in 2001 contains a history of the Tencel development, the second extract of which appears below. (see the original for references -  click here for first extract)

NMMO emerged as the best of the amine-oxides and a team at American Enka demonstrated its commercial potential in the late '70's. In their laboratories in Enka, North Carolina, Neil Franks and Julianna Varga, developed a way of making a more concentrated, and hence economical, solution of cellulose, by carefully controlling the water content of the system.

In this Figure from USP41926282 the concentrations of water and cellulose where complete dissolution of the cellulose occurs (at 95C), lie between lines B and C. Between lines A and B there can be 95% confidence that the solution would be free from undissolved cellulose fibres, and to the right of Line A, undissolved cellulose fibres are bound to be present. Similarly, between C and D there is a 95% chance that crystals of undissolved NMMO will be present, and such crystals will always be present to the left of line D.

Clarence C. McCorsley III, also at Enka, developed the key elements of several possible commercial processes. In one, cellulose pulp sheets were soaked in NMMO solution, and after mild heat and vacuum treatment to adjust the water content, the ground-up sheet was fed to an extruder from which fibres could be spun. In another, the solution was made in a large mixer prior to casting it as thick film, freezing it solid, and grinding up into chips for later extrusion. In a continuous process, a vented extruder fed directly with the ground-up wood-pulp and NMMO, mixes the ingredients, creates the solution by removing excess water and volatiles through the vent, and feeds the spinning pumps.

Both American Enka and Courtaulds set up pilot plant work in the early eighties with the objectives of developing the fibre spinning and solvent recovery operations. Courtaulds commercialized first and this, and the continuing development of lyocell is dealt with by White , who from the outset of practical work in 1979, led the lyocell development effort at Courtaulds.

(more to come)