Thursday 6 December 2012

Toray "Foresse": Melt Spinning of Thermoplasticized Cellulose

Yoshitaka Aranishi of Toray Industries Inc., Mishima (Japan) described Toray’s range of polymers made from biomass, including the world’s first 100% bio-based polyester, but focussed on the development of melt-spinnable cellulose esters.  Nonwovens have in the past been made from melt-spun cellulose acetate, hydroxypropyl-cellulose, phenylacetoxy-cellulose and trimethylsilyl cellulose but these fail to give the necessary high-speed and stable production.  Toray has now optimised a mixture of cellulose esters which when blended with a plasticiser can be spun at high speed (2000 m/min mentioned) into a wide range of fibres with a wide range of cross-sections or bicomponency, and then de-plasticised.  Hollow fibres, X-shapes and Islands-in-a-Sea bicomponents with PLA were shown.  Full orientation occurs within 20 cms of the spinnerette compared with over a metre for PET.  The only fibre properties provided during the talk were moisture regain being 10 times that of PET (i.e. very hydrophilic), the refractive index being lower (more lustrous and vivid after dyeing) and a modulus less than half that of PET (giving much softer fabrics).  More information on this “Foresse” fibre emerged in questions:
  •       The polymer is a mixture of acetate and propionate esters.
  •          “Foresse”  is now 60% bio-based but the esterifying agents will be made from bio-mass eventually to give a 100% bio-based thermoplastic.
  •          9-18% of plasticiser is compounded in to get spinnability.
  •          Tg is 110oC if the plasticiser is left in or 160oC when it is washed out.
  •          The final fibre melts progressively between 220-260oC above which it degrades.
  •          The process is more economical and cleaner and safer (i.e. solvent-free) compared with traditional dry-spun cellulose acetate production.

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