Monday, April 22, 2013

The Techtextil Launch of Courtaulds Lyocell (1995)

Here's a photograph of the stand  built for the launch of lyocell into nonwovens, technical textiles and special papers at Techtextil 95. "Courtaulds Lyocell" was a name chosen to suggest that this lower priced matt version of Tencel was not really Tencel and not to be used in fashion textiles.  Lenzing were using the "Lenzing Lyocell" brand at this time.

Susan Conrad then MD of CMT International and Leslie Millard MD of the Design Distillery were responsible for developing the concept, construction and delivery of the stand.  Trevor Maggs, a freelancer working for CMT wrote much of the copy for the brochures.

Tuesday, April 16, 2013

Solvent Spun Rayon: Prof Turbak's view of the early history (Part 2)

The second extract of Prof. Alban Turbak's chapter on dissolution of cellulose:

Other Cellulose Solvent Systems
In each and every instance of dissolution of cellulose ... thermodynamic factors can be delineated and shown to have a significant and controlling effect on the success of the dissolution process.  In each case the solvent system swells the cellulose and then modifies the molecule either by derivatizing, proton weakening or removal, or by  complexing, to give  a new intermediate specie that can more readily react with the liquid solvent system.

Thus, all cellulose solvent systems can be categorized under 4 mechanisms:
a)    Cellulose as an acid
b)    Cellulose as a base
c)    Cellulose unstable derivative
d)    Cellulose stable derivatives
This chapter will review selected solvent systems involving  areas a, b, and c. Stable derivatives (d) will not be discussed.  All compounds can be considered to be acids or bases relative to some other stronger specie. For example;

       (A) is an Acid      relative to       Base  (B)
       HCl, ­­­H2SO4                              Carboxylic Acids
       Phosphoric                              Acetic, Cellulose
       Phenol                                     NaOH, Sodium Carbonate
       Alcohol                                   NaOH, sodium Metal
       Cellulose                                NMMO, N2N4
       Li(+)/DMAc                              Cellulose
      Cellulose-OH                           Unsolvated  anhydrous Cl(-)
      Hydrocarbons,(isobutane)           NaNH2

It may seem odd to realize that cellulose can act either as an acid or a base, yet this is exactly the case; especially in anhydrous or limited aqueous systems .

Water is an excellent swelling liquid for cellulose and opens millions of internal pores  in the cellulose  microfibrillar structure .  However, H2O is itself both an acid or a base depending on the other molecular specie. Therefore, water normally reacts more rapidly than the cellulose with incoming molecules and this totally disrupts the effectiveness of the incoming potential dissolving moiety.

See Also  "Solvent Spun Rayon" and "Regenerated Cellulose Fibres"

Tencel Sales by Region 92-98 (1998)

This graph of actual Tencel sales prepared in 1998 illustrates the collapse referred to in an earlier post .

At a time when the Mobile plant capacity was said to be 55000 tpy, and the new Grimsby plant was due to add a further 42000 tpy, actual sales in the first quarter of 98 were only 5800 tons/quarter or at a 23,200 tonne/year rate.  Lenzing had 12,000 tonnes capacity and had postponed starting up the other stream at Heiligenkreuz.

First quarter 1995 caused consternation also with an annual sales rate of less than 3200 tonnes.  

However taking the long view (which was hard at the time!) smoothing out the noise gives a nice upward trend suggesting 60,000 tpy sales by 2004/5.

Friday, April 12, 2013

Solvent Spun Rayon: Prof Turbak's view of the early history (Part 1)

Prof. Alban Turbak did ground-breaking work on the dissolution of cellulose during the 1970's while with ITT Rayonier.  As he mentions in this extract of his introduction to non-NMMO cellulose dissolution methods in Regenerated Cellulose Fibres, his 1977 "Solvent Spun Rayon" book  provided one of the stimulii for research work to begin at Courtaulds.  His definition of these fibres as "reconstituted" rather than "regenerated" no longer figures in the nomenclature.

Ever since the discovery of the xanthate process by Cross and Bevan in 1892 and its commercialization in the early 1900’s there have been many efforts to dissolve cellulose directly in non-aqueous solvents which would be both easy to use and readily recoverable. The viscose process produces good quality films and fibers. However, by the mid 1970’s pollution problems and price competition from synthetic films and fibers had seriously eroded the cellophane and rayon markets. In order to remain commercially competitive it was necessary for rayon and cellophane producers to seek simpler less polluting processes.

In the mid 1970’s I.T.T. Rayonier decided that to preserve their pulp markets it would be in their best interest to take the lead in trying to find new ways to make rayon. To their credit, Rayonier’s management authorized a multi-million dollar research effort which ran for a period of 7 years at the I.T.T. Rayonier Eastern Research Division Laboratories. The overall goals were to develop new direct cellulose solvent systems which would require lower investment costs and be readily recovered and recycled in closed loop non-polluting systems.

In order to identify potential previously examined solvent candidates an extensive literature search was made covering 80 years of cellulose solvent reports A close examination and evaluation of these reports from a physical organic viewpoint led to a review paper which, for the first time, delineated all cellulose solvent systems into four simple categories.(1) Subsequently, several other solvent system reviews have been reported (2,3) Rayonier reported some of their preliminary results at an American Chemical Society symposium in New Orleans in 1977.(4) As a result of Rayonier’s stimulus other companies and research universities undertook cellulose solvent research projects.

Concurrently, Franks, McCorsley and Varga at the American Enka Corp were deeply involved in evaluating N-Methyl Morpholine-N- Oxide (NMMO).(5). The Enka NMMO technology was subsequently pursued by Courtaulds in England. As is now well known, Courtaulds’ Tencel® NMMO solvent spun cellulose fiber technology is now a major commercial success and solvent spun cellulose films for food packaging are currently under intense investigation. Tencel® lyocell is actually not a regenerated cellulose fiber but, rather, is a reconstituted cellulose fiber since it was never derivatized.

1. Turbak, A.F., Hammer. R.B., et al, Cellulose Solvents, CHEMTECH, 10,51-57, Jan. 1980
2. Hudson, S.M., and Cuculo, J.A., The Solubility of Unmodified cellulose: A Critique of the Literature, J. Macromol. Sci.,18, (1) 1-82,1980
3. Johnson, D.C., Solvents for Cellulose, Cellulose Chemistry and its Applications, Ellis Harwood, Ltd., Chinchester, 1985
4. Turbak, A.F., Solvent Spun Rayon, Modified Fibers and Derivatives, ACS Symposium # 58, Amer. Chem. Soc., Washington, D.C., 1977
5. Franks, N.E., McCorsley, C.C., and Varga, J.K., U, S. Patent 4,142,913 March, 1979; U.S. Patent4,196,282 April, 1980