Process for manufacturing lyocell filament yarn and an apparatus thereof

A process for manufacturing lyocell filament yarn with improved mechanical properties, the process comprising:

• a) preparing a homogenous solution of cellulose in concentrated NMMO solution to obtain cellulose dope, and storing said cellulose dope in a lyocell dope vessel;
• b) pumping stored cellulose dope via a metering pump into a spin pack containing a spinneret that extrudes the cellulose dope as spun filaments;
• c) stretching extruded spun filament yarn using a winder while passing filaments through an air-gap at controlled conditions and in a regeneration bath containing a solution for partial regeneration of the extruded spun filament yarn;
• d) guiding the partially regenerated filament yarn to filament guiding drum which passes said filament yarn to a main drum spinning at a speed less than the winder speed, said main drum having a filament yarn washing section and a filament yarn drying section wherein the filament yarn is fully regenerated in the filament yarn washing section by passing it through sequential washing zones, each successive washing zone containing a washing solution of successively decreasing concentration of NMMO, said concentration successively decreasing up to 0% by weight of NMMO in filament, maintained by circulating system, and
• e) drying the washed filament yarn on the filament yarn drying section at a temperature selected from the range of 40° C. to 100° C.;
• wherein said process is carried out using an apparatus comprising:
• i) at least one lyocell dope vessel for storing said cellulose dope;
• ii) at least one metering pump for pumping said cellulose dope into at least one spin pack containing at least one spinneret that extrudes the cellulose dope as spun filament yarn;
• iii) a regeneration bath containing a solution for partial regeneration of the extruded spun filament yarn;
• iv) at least one winder for stretching extruded spun filament yarn while it passes through an air-gap of controlled conditions and the regeneration bath solution to create a stretched yarn;
• v) an individual yarn guiding drum;
• vi) a main drum having a filament yarn washing section and a filament yarn drying section,
• wherein the individual yarn guiding drum guides the stretched yarn from the at least one winder to the main drum spinning at a speed less than the winder speed, wherein the main drum speed to winder speed is selected from a ratio of 1.00 to 0.85, wherein the filament yarn washing section comprises sequential washing zones, each successive washing zone containing a washing solution of successively decreasing concentration of N-methyl morpholine N-oxide (NMMO), said concentration successively decreasing to up to 0% by weight of NMMO, and
• wherein the filament yarn drying section has a temperature of 40° C. to 100° C. for drying the washed filament yarn to create a dried lyocell filament yarn having a tenacity greater than 3.2 grams per denier and elongation greater than 8%;
• and
• vii) a circulating pump to maintain uniform concentration of the NMMO in each washing zone.