Technical fibers, whether natural or synthetic in origin, are produced via a series of steps which transform the raw material into a viscous, homogenous, degassed spinning dope.
For any fibers which require a dissolving step LIST KneaderReactor technology can produce high quality spinning dope which results in high fiber quality with maximum throughput and at minimum costs.
The unique process characteristics of the KneaderReactor provide intensive mixing and kneading, constant surface renewal and variable residence times. The scale-up to large industrial capacities in one single line is one of the many advantages of the LIST Technology.
Cellulose and additives are dissolved continuously in the LIST KneaderReactor, which provides thermal treatment, evaporation, and degassing along with intensive mixing. The result is a glass-clear, light yellow spinning solution that is highly homogeneous and free from bubbles and dissolved gases.
Depending on the process the solvent might be N-Methylmorpholine-N-Oxide (NMMNO), various ionic liquids, acids or caustics.
Aramid fibers are typically wet-spun from a viscous solution made of poly(p-phenylene terephthalamide) (PPTA) polymer in concentrated sulfuric acid. The thermal energy released during the exothermic dissolving process helps to melt and dissolve the polymer. The polymer solution is viscous and non-Newtonian. The requirement is to create a homogenous, degassed solution with a controlled high polymer concentration.
- Effective self-cleaning to minimize dead zones, product accumulation and product degradation
- Excellent kneading and mixing for better homogenization
- Low shear processing
- Effective heat transfer
- High surface renewal efficiency
- Large free vapour volume
- Precise and uniform temperature control due to large heat transfer areas
- Continuous processing
- Processing of sticky and highly viscous products
- Narrow residence time distributions (plug flow)
- Wide and flexible range of average residence times
- Reliable process scale-up from pilot to industrial units